JP2016537797A - X-ray source using straight line accumulation - Google Patents

Abstract

The present application discloses a compact source for generating high brightness X-rays. Higher brightness is achieved by electron beam bombardment of multiple regions aligned with each other to achieve linear accumulation of X-rays. This is a novel with multiple microstructures of X-ray generating material, manufactured by aligning discrete X-ray emitters or in intimate thermal contact with a high thermal conductivity substrate. This is realized by using an X-ray target. This allows heat to be more efficiently removed from the x-ray generating material, which in turn allows impact of the x-ray generating material with higher electron density and / or higher energy electrons, Provides greater x-ray brightness. The arrangement of multiple microstructures allows the use of an on-axis convergence angle, also known as “angle 0 °” x-ray emission, but aligned to appear to have a single source Allows accumulation of X-rays from multiple microstructures.

Description

[Cross-reference of related applications]
No. 61 / 880,151 (filing date: September 19, 2013), 61 / 894,073 (filing date: October 22, 2013), 61 / 931,519 (filing date: January 24, 2014), 62 / 008,856 (filing date: June 6, 2014), and 14 / 490,672 (filing date) : September 19, 2014), all of which are hereby incorporated by reference in their entirety. This application is also related to US patent application Ser. No. 14 / 465,816 (filing date: August 21, 2014), which is hereby incorporated by reference in its entirety and is also included in Appendix A. As partly included.

  The embodiments disclosed herein relate to a high brightness source of X-rays. Such high intensity sources can be useful for a variety of applications where X-rays are used, including manufacturing inspection, metrology, crystallography, structure / composition analysis, and medical imaging / diagnosis systems.

  The first discovery of X-rays by X-rays in 1895 [W. C. Rongen, Eine Neue art von Strahlen (Wiirzburg Verlag, 1895); “On a New Kind of Rays”, Nature, 53, pp. 274-276 (January 23, 1896) It was born by chance while experimenting with electron impact on the target. These high-energy, short-wavelength photons are now used in medical applications and diagnostic evaluation, as well as security inspection, industrial inspection, quality control, and failure analysis, as well as crystallography, tomography, X-ray fluorescence analysis, and the like It is used on a daily basis for scientific applications.

  Experimental x-ray sources were subsequently improved by Coolidge in the early 20th century [see, for example, William D. et al. US Patent Nos. 1,211,092 (issue date: January 2, 1917), 1,917,099 (issue date: July 4, 1933), and 1,946, by Coolidge No. 312 (issue date: February 6, 1934)], then, in the latter half of the 20th century, a system that generated a very strong X-ray beam using a synchrotron or a free electron laser (FEL) was developed. . However, these synchrotron and FEL systems are physically very large systems, and their installation required large buildings and large land. In small, practical laboratory-based systems and instruments, most x-ray sources still use the basic mechanism of the Coolidge tube.

An example of a transmission X-ray source 08, which is the simplest X-ray source, is illustrated in FIG. The source generally comprises a sealed vacuum tube 02 or a vacuum environment (typically 10 ⁻⁶ Torr or higher vacuum) provided by constant evacuation, and the negative and positive electrodes of the high voltage source 10 on the outside of the tube. From the sealed conductors 21 and 22 leading to the various elements inside the vacuum tube 02. The source 08 typically includes a plurality of mounts 03 that secure the vacuum tube 02 in the housing 05, and the housing 05 may be lead or the like to prevent X-rays from being emitted in unwanted directions by the source 08. The shield material may be additionally provided.

  Inside the vacuum tube 02, the emitter 11 connected to the high voltage source 10 through the conducting wire 21 functions as a cathode, and in many cases, a current is passed through the filament to generate a beam of electrons 111. The target 01 is electrically connected to the opposite high voltage conductor 22 which is at a low voltage, thereby acting as an anode. The emitted electrons 111 are accelerated toward the target 01 and collide with the target 01 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of the electrons 111 with the solid target 01 causes multiple effects including the emission of X-rays 888. A portion of the x-ray 888 exits the vacuum tube 02 through a window 04 designed to pass x-rays. In the configuration shown in FIG. 1, the target 01 is deposited or directly mounted on the window 04, which forms part of the wall of the vacuum chamber. In other prior art embodiments, the target may be formed as an integral part of the window 04 itself.

Another example of a typical x-ray source design is a reflective x-ray source 80, illustrated in FIG. Again, the source generally comprises a sealed vacuum tube 20 or a vacuum environment (typically 10 ⁻⁶ Torr, or higher vacuum) maintained by evacuation, with the negative electrode of the high voltage source 10 on the outside of the tube. And sealed conductors 21 and 22 leading from the positive electrode to various elements inside the vacuum tube 20. The source 80 typically includes a plurality of mounts 30 that secure the vacuum tube 20 within the housing 50, and the housing 50 may be lead or the like to prevent X-rays from being emitted in unwanted directions by the source 80. The shield material may be additionally provided.

  Inside the vacuum tube 20, the emitter 11 connected to the high voltage source 10 through the conductive wire 21 functions as a cathode, and in many cases, a current is passed through the filament to generate a beam of electrons 111. The target 100 supported by the target substrate 110 is electrically connected to the high-voltage conductive wire 22 and the target support portion 32 on the opposite side, which are at a low voltage, thereby functioning as an anode. The electrons 111 accelerate toward the target 100 and collide with the target 100 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of electrons 111 with the target 100 causes multiple effects including X-ray emission. Some of the X-rays exit the vacuum tube 20 and pass through a window 40 that is transparent to the X-rays.

  In another prior art embodiment of a reflective x-ray source (not shown in FIG. 2), the target 100 and substrate 110 can be integrated or constitute a solid block of the same material, such as copper (Cu). Can do. Although not shown in FIGS. 1 and 2, as is generally used in practice, a plurality of electron lenses (electrostatic lenses or electromagnetic lenses) are provided to guide and shape the electron path, thereby making it more concentrated. The focused beam can be formed on the target. Similarly, an electron source comprising a plurality of emitters may be provided, providing a larger distributed source of electrons.

  When electrons collide with the target 100, they can interact in several ways. These are illustrated in FIG. Electrons in the electron beam 111 collide with the target 100 at the surface 102, and electrons passing through the surface multiply these energies by multiplying the footprint (area) of the incident electron beam by the electron penetration depth. Transmit to the target 100 within a generally defined interaction volume 200. For very small sized incident electron beams (eg, beam diameter less than 100 nm), the interaction volume 200 is typically in the shape of “pear” or “tears” in three dimensions, and the direction of electron propagation Symmetrical shape around the center. For larger beams, the interaction volume is represented by this “tears” shaped convolution using a transverse beam intensity profile.

The equation commonly used to estimate the penetration depth of electrons into a material is Pott's Law [P. J. et al. Potts, 1987, published by Springer Netherlands, “A Handbook of Silicate Rock Analysis”, Chapter 10 “Electron Probe Microanalysis”, page 336], according to which the penetration depth V in micron units is k. It is stated that the electron energy E ₀ is 3/2 and is related to 10% of the value divided by the material density.
For lower density materials, such as diamond substrates, the penetration depth is much greater than for higher density materials, such as most elements used for x-ray generation.

  There are multiple energy transfer mechanisms that can occur. Throughout the interaction volume 200, electron energy can simply be converted to heat. Some of the absorbed energy can typically cause the generation of secondary electrons detected from the region 221 located near the surface, while some of the electrons are backscattered. This can also be detected from the somewhat larger area 231 due to these high energies.

  X-rays 888 are generated and emitted in all directions outwardly throughout the interaction volume 200, including regions 221 and 231 near the surface and extending approximately three times deep into the target 100. X-ray emission can have a complex energy spectrum. When electrons enter the material, they slow down and lose energy. Accordingly, a plurality of X-rays having different characteristics are generated at a plurality of different portions of the interaction volume 200. A typical X-ray emission spectrum emitted when 100 keV electrons collide with a tungsten target is illustrated in FIG.

  As shown in FIG. 4, a broad spectrum of X-ray emission 388 results from an electron that has diverted from its initial trajectory, which is how close it passes to various nuclei and other electrons. Depends on. The decrease in electron energy and the change in momentum associated with the change in direction cause the emission of X-rays. Because a wide range of deflections and decelerations can occur, due to the approximate statistics of electron collisions with atoms of the target material, the energy change is continuous and therefore the energy of the generated X-rays is also continuous. Larger emissions occur on the low energy side of the energy spectrum, and much less occurs on the high energy side, reaching the absolute limit where there is no x-rays of energy greater than the original electron energy (100 keV in this example). . Due to the origin of electronic deceleration, this type of continuous x-ray emission 388 is commonly referred to as bremsstrahlung, following the German word “bremssen” for “braking”.

  These continuous x-rays 888 occur throughout the interaction volume shown in FIG. 3 as the largest shaded portion 288 of the interaction volume 200. At lower energies, the bremsstrahlung x-ray 888 is typically emitted isotropically, i.e. with little intensity change with respect to the emission direction [e.g. Gonzales, B.M. Cavness, S.C. William, “Angular distribution of thick-target brmsstrahlung produced by elected with initial energies ranging from 10 to 20 keV incident. Rev. A, 84, 052726 (2011)]. Higher energy excitation may increase the “0 degree” emission for an incident beam perpendicular to the electron beam, ie, 90 degrees to the target surface. [For example, J. et al. G. Chervenak, A.M. Liuzzi, "Experimental thick-target bremstrength spectrum from the range in the range 10 to 30 keV", Phys. Rev. A, 12 (1), pp. 26-33 (July 1975)].

  As shown in FIGS. 1 and 2, the X-ray source 08 or 80 typically has a window 04 or 40. This window 04 or 40 may additionally have a filter that attenuates low energy x-rays, such as an aluminum sheet or layer, to produce the modified energy spectrum 488 shown in FIG.

  When the electron energy is larger than the binding energy of the inner shell (core shell) electrons of the element in the target, electrons are emitted from the shell (ionization), and vacancies can be generated. Second, the less strongly bound outer shell electrons can freely transition to the inner shell vacancies, filling the vacancies. As the filled electrons move to lower energy levels, excess energy is released in the form of X-ray photons. This emission is known as a “characteristic” emission because the energy of the photon indicates the characteristics of the chemical element that generates the photons.

In the example shown in FIG. 4, 100 keV electrons can ionize K-shell electrons of a tungsten atom having a binding energy of 69.5 keV. When the vacancies are filled by L-shell electrons with 10.2 keV binding energy, the X-ray photon has an energy equal to the energy difference between these two levels, ie K _α1 = 59.3 keV . Similarly, the transition from the M shell to the K shell is shown as K _β1 = 67.2 keV. Multiple separations occur at various levels and can cause slight changes in energy, for example, _Kβ1 , _Kβ2 , _Kβ3 .

  Since these discrete emission lines depend on the atomic structure of the target material, emission is generally referred to as “characteristic lines”. This is because the “characteristic line” indicates the characteristics of a specific material. In the example of the X-ray emission spectrum shown in FIG. 4, the sharp line 988 is the “characteristic line” of tungsten. Individual characteristic lines can be very bright and can be monochromated with a suitable filter or crystal monochromator if a monochromatic source is desired. The relative X-ray intensity (flux) ratio of the characteristic line to the bremsstrahlung depends on the element and the incident electron energy and can vary substantially. In general, the maximum ratio for a given target material is obtained when the incident electron energy is 3 to 5 times the ionization energy of the core electrons.

  Returning to FIG. 3, these characteristic X-rays 388 occur primarily at a fraction of the electron penetration depth, shown as the second largest shaded portion 248 of the interaction volume 200. The relative depth is typically affected to some extent by the energy of the electrons 111, which typically decreases with increasing depth. If the electron energy does not exceed the binding energy of the electrons in the target, no characteristic X-rays are emitted. Maximum emission of characteristic lines can occur upon impact with electrons having 3 to 5 times the energy of emitted characteristic X-ray photons. Since these characteristic X-rays are caused by atomic emission between multiple electron shells, the emission is generally completely isotropic. The actual size of this interaction volume 200 will vary depending on the electron energy and angle of incidence, surface topography and other properties (including local charge density), and the density and atomic composition of the target material. obtain.

  Depending on the application, X-rays with a broad spectrum may be appropriate. In other applications, a monochromatic source may be desired or even required for the required sensitivity or resolution. In general, the composition of the target material is selected to provide an X-ray spectrum that has ideal characteristics for a particular application, such as a strong characteristic line at a particular wavelength of interest, or bremsstrahlung over a desired bandwidth. .

  Control of the X-ray emission characteristics of the source depends on the choice of electron energy (typically changed by changing the acceleration voltage), the choice of X-ray target material, and the shape of the X-ray collection from the target. Can be controlled.

As illustrated in FIG. 3, X-rays can be emitted isotropically, but as shown in FIGS. 5A-5C, X-ray emission 888 within a small solid angle toward the source window 440. Only collected. Defined as the number of x-ray photons per ^second , solid angle (mrad ² ), and x-ray source area (mm ² ) (depending on the measurement method, the definition includes a 0.1% bandwidth window) X-ray brightness (sometimes called “brilliance”) is related to obtaining a good signal-to-noise ratio for downstream applications, so it is an important figure for the source. It is an advantage.

  Luminance can be increased by adjusting geometric factors to maximize the collected X-rays. As illustrated in FIGS. 5A-5C, the surface of the target 100 of the reflective x-ray source is mounted at an angle θ (as also shown in FIG. 2) and is subject to impact by the dispersed electron beam 111. receive. Emissions through window 440 are aligned at five equally spaced intervals for three target angles, θ = 60 ° (FIG. 5A), θ = 45 ° (FIG. 5B), and θ = 30 ° (FIG. 5C). A set of emission spots 408 is shown. For a source with a high angle θ, the brightness decreases as the five spots are more spread out with respect to the solid angle centered on the window 440. On the other hand, at a low angle θ, the five source spots appear to be closer together, thus emitting more X-rays within the same solid angle, resulting in an increase in brightness.

  In principle, a source mounted at θ = 0 ° can be considered to have the maximum possible brightness because all the sources can be superposed and accumulated in appearance. In practice, the emission at 0 ° occurred because it occurred parallel to the surface of the solid metal target for conventional sources, and X-rays had to propagate along a long distance of the target material before emission. Most of the x-rays are attenuated (reabsorbed) by the target material, reducing brightness. In practice, a source with a take-off angle of about 6 ° to 15 ° (depending on source configuration, target material, and electron energy) often provides a practical maximum brightness, which reduces the apparent size of the source. Condensates and reduces reabsorption in the target material and is therefore commonly used in commercial x-ray sources.

  The effective source area is the projected area viewed along the direction in which x-rays are collected for use, i.e. along the axis of the x-ray beam. Due to the limited electron penetration depth, the effective source area of an incident electron beam having a size comparable to or larger than the electron penetration depth is the distance between the axis of the x-ray beam and the surface of the target. Depends on the angle (referred to as “take-off angle”). When the electron beam size is much larger than the electron penetration depth, the effective source area decreases with decreasing extraction angle. This effect was used to increase the brightness of the X-ray source. However, this advantage is limited for wide, flat targets. The reason is that as X-rays propagate to the surface, X-ray absorption from the X-ray generation point inside the target increases, and this X-ray absorption increases as the extraction angle becomes smaller. Typically, a take-off angle of about 6 ° was reached due to a compromise between brightness enhancement with lower angles and brightness reduction with reabsorption.

Another way to increase the brightness of an x-ray source for bremsstrahlung is to use a higher atomic number Z target material. The reason is that as the atomic number of the material increases, the efficiency of generating X-rays for bremsstrahlung increases correspondingly. Furthermore, the X-ray emitting material should ideally have good thermal properties, such as a high melting point and high thermal conductivity, to allow higher electron power on the source to increase X-ray generation. . For these reasons, targets are often manufactured using tungsten with an atomic number Z of 74. Table 1 shows commonly used X-ray targets, multiple additional potential target materials (especially useful for the particular characteristic line of interest), and some materials that can be used as a substrate for the target material. The materials are described. The melting point and the heat / electric conductivity are values in the vicinity of 300 K (27 ° C.). Most of the values are quoted from the 90th edition of CRC "Handbook of Chemistry and Physics" [Boca Raton, Florida, CRC Press, 2009]. Several other values are cited from various sources found on the Internet. It should be noted that for some materials, such as sapphire, thermal conductivity may be an order of magnitude greater when cooled to temperatures below the liquid nitrogen temperature (77 K) [eg, E.C. R. See Dobrovinskaya et al., “Sapphire: Material, Manufacturing, Applications”, Springer Science + Business Media, LLC, Chapter 2.1.5 “Thermal Properties”].

  Other ways to increase the brightness of the x-ray source include increasing the overall current, or focusing the electron beam to a smaller spot using, for example, multiple electron lenses, either by electron flow. To increase the electron energy by increasing the density or by increasing the accelerating voltage (this increases the X-ray generation per unit electron energy deposited on the target, and more in the characteristic line May also cause the release of

  However, all these improvements are limited in that they increase the amount of heat generated within the interaction volume. This problem is exacerbated by having the target in a vacuum so that no air cooling of the surface by convection can occur. If excessive heat is generated in the target, the target material can undergo phase changes, even melting and evaporation. Since most of the energy deposited on the target by the electron beam becomes heat, thermal management techniques are an important tool for creating a better x-ray source.

  One prior art technique developed to address this problem is the rotating anode system illustrated in FIG. 6A. FIG. 6A shows a cross-section of a rotating anode x-ray source 580 having a target anode 500 that typically rotates between 3,300 rpm and 10,000 rpm. The target anode 500 is connected to the rotor 520 by a shaft 530, and the rotor 520 is supported by a conductive bearing 524 that connects to the conductor 22 and the positive electrode of the high voltage source 10 through its mount 522. The rotation of the rotor 520, shaft 530, and anode 500, all within the vacuum chamber 20, is typically inductively driven by a stator winding 525 mounted outside the vacuum.

  In FIG. 6B, the surface of the target anode 500 is shown in more detail. The edge 510 of the rotating target anode 500 may be chamfered diagonally, and the source of the electron beam 511 is in a position to direct the electron beam to the chamfered edge 510 of the target anode 500, and the target spot X-ray 888 is generated from 501. Since the target spot 501 generates X-rays and is heated, the target anode 500 rotates, so that the heating spot is separated from the target spot 501, and the electron beam 511 irradiates a lower temperature portion of the target anode 500. Prior to being heated again when passing through the hot spot 501, the hot spot has time for one revolution to cool. By continuously rotating the target anode 500, X-rays are generated from a fixed single spot, but the total area of the target irradiated by the electron beam is substantially larger than the electron beam spot, and the electron energy. Is effectively spreading over a larger area (and volume).

  Another approach to mitigating heat is to use a target with a thin layer of target X-ray material deposited on a high thermal conductivity substrate. For electrons with energies up to 100 keV, because the interaction volume is thin, the target material itself does not need to be thicker than a few microns and can be deposited on a substrate such as diamond, sapphire, or graphite that quickly releases heat. However, as shown in Table 1, since diamond has a very low electrical conductivity, any anode design made on the diamond substrate can be electrically connected between the anode target material and the high voltage positive electrode. Still need to be provided. [The anode of the X-ray source attached to the diamond can be U.S. Pat. No. 4,972,449 to Upadya et al. US Pat. No. 5,148,462 to Spitsyn et al. As described by US Pat. No. 6,850,598 to Fryda et al.].

  The substrate may also have multiple pathways for coolant to remove heat from the substrate, for example, a liquid such as water or ethylene glycol, or a gas such as hydrogen or helium (eg, US Pat. No. 5 by Paul E. Larson). , 602,899). Water cooled anodes are used in a variety of x-ray sources, including rotating anode x-ray sources.

  The substrate can then be attached to a heat sink having copper or some other material selected for its thermal conductivity properties. The heat sink may also have multiple paths for coolant to remove heat (see, eg, US Pat. No. 8,094,784 by Edward J. Morton). In some cases, thermoelectric coolers or cryogenic systems have been used to provide additional cooling to x-ray targets attached to a heat sink. Again, all is aimed at achieving high X-ray brightness without causing melting or damage of the target material due to overheating.

  Another approach to mitigating heat for a microfocus source is to use a target created by a liquid metal jet. The electrons impact a conductive jet of liquid gallium (atomic number 31), and the heated gallium flows out of the electron irradiation volume with the jet, thus enabling a high current density. [For example, M.M. Otendal et al., “A 9 keV electron-impact liquid-gallium-jet x-ray source”, Rev. Sci. See Instrum, 79, 016102, (2008)].

  Although effective for certain environments, these sources still have room for improvement. Liquid metal jets require elaborate water supply and drainage systems and consumables, limiting the materials used (and thus the atomic number values and their associated spectra), making it difficult to increase to higher power. In the case of a uniform solid material thin film target coated on a diamond substrate, there is still a limit to the amount of heat that can be tolerated before damage to the film can occur, even when used in a rotating anode configuration. Heat conduction only occurs through the bottom surface of the membrane. Even in the lateral dimension, there are the same conduction problems that exist in bulk materials.

  Thus, there is a need for an x-ray source that can be used to achieve high x-ray brightness through the use of high electron current density, but it is still sufficient to accommodate laboratory and desktop environments, or portable It is so small that it is even useful for the device. Such bright sources may allow X-ray based tools that provide better signal-to-noise ratios for image processing and other scientific and diagnostic applications.

  The present disclosure presents a novel x-ray source that has the potential to reach orders of magnitude brightness compared to existing commercial x-ray technology. Higher brightness is achieved to some extent by using a new configuration for the X-ray target used to generate X-rays from electron beam bombardment. The configuration of the X-ray target is in close thermal contact (such as embedded or embedded) with a high thermal conductivity substrate so that heat is more efficiently removed from the X-ray generating material. May have a plurality of microstructures of one or more selected x-ray generating materials fabricated on the surface. This in turn allows the impact of high electron density and / or high energy electrons and the X-ray generating material, resulting in greater X-ray brightness.

  A significant advantage of some embodiments is that the arrangement of multiple microstructures allows the use of on-axis convergence angles and from multiple microstructures aligned to appear to originate from a single source. X-rays can be accumulated, and can be used to align X-ray emission at “angle 0 °”. Linear accumulation of X-rays from multiple sources results in greater X-ray brightness.

  Some embodiments of the present invention add a plurality of X-ray optical elements that collect X-rays emitted from one structure and refocus them onto the X-rays from the second structure. Prepare. This x-ray relay can also provide greater x-ray brightness.

  Some embodiments of the present invention comprise an additional cooling system that removes heat from the anode or anodes. Some embodiments of the present invention further include rotating the anode or anodes having a microstructured pattern target to further dissipate heat and increase cumulative x-ray brightness.

1 shows a schematic cross-sectional view of a standard prior art transmission X-ray source.

1 shows a schematic cross-sectional view of a standard prior art reflective x-ray source.

Figure 2 shows a cross-sectional view of the interaction of electrons with the material surface of a prior art X-ray source.

2 shows a typical emission spectrum of a tungsten target.

Figure 3 shows the emission from a prior art target when the target is at a tilt angle of 60 °.

Figure 3 shows the emission from a prior art target when the target is at a 45 ° tilt angle.

Figure 3 shows the emission from a prior art target when the target is at a 30 ° tilt angle.

1 shows a schematic cross-sectional view of a prior art rotating anode X-ray source.

FIG. 6B shows a top view of the anode of the rotating anode system of FIG. 6A.

1 shows a schematic cross-sectional view of one embodiment of an X-ray system according to the present invention.

FIG. 2 shows a perspective view of a target having a latticed embedded rectangular target microstructure on a large substrate that can be used in some embodiments of the present invention.

FIG. 6 shows a perspective view of a variation of a target having a latticed embedded rectangular target microstructure on a large substrate for use with a focused electron beam that may be used in some embodiments of the invention.

FIG. 5 shows a perspective view of a variation of a target having a microstructure of a grid-like embedded rectangular target on a cut substrate that can be used in some embodiments of the invention.

FIG. 6 shows a perspective view of a variation of a target having a microstructure of a grid-like embedded rectangular target on a substrate with shelf-like recesses that can be used in some embodiments of the present invention.

FIG. 2 shows a cross-sectional view of electrons incident on a target having a target microstructure on a large substrate that can be used in some embodiments of the invention.

FIG. 13 shows a cross-sectional view of some X-rays emitted by the target of FIG.

FIG. 4 shows a perspective view of a target having a single rectangular microstructure disposed on a substrate with a recessed area that can be used in some embodiments of the present invention.

FIG. 4 shows a perspective view of a target having a plurality of rectangular microstructures arranged in a row on a substrate having a recessed area that may be used in some embodiments of the present invention.

FIG. 2 shows a perspective view of a target having a microstructure of a grid-like embedded rectangular target that can be used in some embodiments of the present invention.

FIG. 16B shows a top view of the target of FIG. 16A.

FIG. 16C shows a side / sectional view of the target of FIGS. 16A and 16B.

FIG. 17 shows a cross-sectional view of the target of FIG. 16 and shows the transfer of heat to a heat conducting substrate that has been irradiated with an electron beam.

FIG. 3 shows a perspective view of a target having an embedded target microstructure in a checkerboard configuration that can be used in some embodiments of the present invention.

FIG. 18B shows a top view of the target of FIG. 18A.

FIG. 19 shows a side / sectional view of the target of FIGS. 18A and 18B.

FIG. 2 shows a perspective view of a target having a microstructure of a grid-like embedded rectangular target disposed on a stepped substrate that can be used in some embodiments of the invention.

FIG. 19B shows a top view of the target of FIG. 19A.

FIG. 20 shows a side / sectional view of the target of FIGS. 19A and 19B.

FIG. 19C shows a cross-sectional view of the target of FIG. 19C that emits X-rays upon electron impact.

Fig. 4 illustrates a collection of X-ray emitters arranged in a linear array that may be used in some embodiments of the present invention.

Figure 2 shows the 1 / e decay length of multiple materials for X-rays with energies ranging from 1 keV to 400 keV.

FIG. 6 illustrates a linear array of x-ray emitters exposed to a normal incidence electron beam that can be used in some embodiments of the present invention.

FIG. 6 illustrates a linear array of x-ray emitters exposed to an electron beam incident at an angle θ that can be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of X-ray emitters exposed to a focused electron beam that can be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of x-ray emitters exposed to an electron beam incident at multiple angles from multiple directions that can be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of x-ray emitters exposed to electron beams of various electron densities that can be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of x-ray emitters exposed to a uniform electron beam that can be used in some embodiments of the present invention.

1 shows a schematic cross-sectional view of an embodiment of an X-ray system according to the invention having a plurality of electron emitters.

Fig. 3 illustrates a collection of various X-ray emitters exposed to electron beams of different electron densities that can be used in some embodiments of the present invention.

FIG. 2 shows a tungsten decay length and CSDA (continuous electron deceleration approximation) diagram over a range of x-ray energies.

FIG. 4 shows a diagram of tungsten attenuation length to CSDA ratio over a range of x-ray energies.

FIG. 4 shows a plot of attenuation length to CSDA ratio for multiple materials over a range of x-ray energies.

FIG. 4 shows a collection of X-ray emitters arranged in a linear array at time step t = 0 in time-divided electron beam irradiation that can be used in some embodiments of the present invention.

FIG. 28B shows the collection of X-ray emitters of FIG. 28A at the next time step t = 1.

2 shows an assembly of X-ray emitters. FIG. 28A at t = 0, FIG. 28B at the next step t = 1, and FIG. 28C at the next time step t = 2.

FIG. 4 illustrates X-ray off-axis emission from a collection of X-ray emitters arranged in a linear array that may be used in some embodiments of the present invention.

FIG. 3 illustrates X-ray off-axis emission from a collection of X-ray emitters arranged in a widely spaced linear array that may be used in some embodiments of the present invention.

1 shows a schematic cross-sectional view of one embodiment of an X-ray system according to the present invention comprising a plurality of electron emitters and a cooling system.

FIG. 31 shows a cross section of the target of the X-ray system of FIG.

1 shows a schematic cross-sectional view of an embodiment of an X-ray system according to the invention comprising a two-surface target.

Fig. 33 shows a cross section of the target of the X-ray system of Fig. 32;

1 shows a schematic cross-sectional view of an X-ray system according to an embodiment of the present invention comprising a plurality of electron emitters that impact both sides of a rotating anode.

Fig. 4 shows a cross section of a plurality of targets aligned for straight line accumulation used in a system according to the invention.

Figure 3 shows a cross section of a plurality of targets having a plurality of microstructures of X-ray generating material aligned for linear accumulation used in a system according to the present invention.

FIG. 4 shows a side view of a target having an x-ray coating that can be bombarded with a distributed electron beam that can be used in some embodiments of the present invention.

FIG. 37B is a perspective view of the target of FIG. 37A and the dispersed electron beam.

FIG. 37B shows a front view of the target and distributed electron beam of FIG. 37A.

FIG. 4 shows a side view of a target having a microstructure that is impacted with a distributed electron beam that can be used in some embodiments of the present invention.

FIG. 38B is a perspective view of the target of FIG. 38A and the dispersed electron beam.

FIG. 38B shows a front view of the target and distributed electron beam of FIG. 38A.

2 shows a cross section of a plurality of targets having a fine structure of an X-ray generating material. Here, a plurality of reflective lenses are used to collect and focus X-rays for use in the system according to the invention.

2 shows cross-sections of a plurality of targets having microstructures of X-ray generating materials in various arrangements. Here, a plurality of reflective lenses are used to collect and focus X-rays for use in the system according to the invention. 2 shows a cross section of a plurality of targets having a fine structure of an X-ray generating material. Here, additional windows and detectors are used to monitor X-rays propagating in the opposite direction.

2 shows a cross section of a plurality of targets having a fine structure of an X-ray generating material. Here, a plurality of Walter lenses are used to collect and focus X-rays for use in the system according to the invention.

1 illustrates a prior art embodiment of a plurality of Walter lenses used for X-rays.

1 illustrates a prior art embodiment of a plurality of Walter lenses having a plurality of cylindrical optical elements.

2 shows a cross section of a plurality of targets having a fine structure of an X-ray generating material. Here, a plurality of capillary lenses are used to collect and focus X-rays for use in the system according to the invention.

1. Basic Embodiment of the Invention FIG. 7 shows one embodiment of a reflective x-ray system 80-A according to the invention. As with the prior art reflective x-ray system 80 described above, the source is typically a sealed vacuum chamber 20 or a vacuum environment maintained by constant evacuation (typically 10 ⁻⁶ Torr or higher vacuum). ) And sealed conductors 21 and 22 leading from the negative and positive electrodes of the high voltage source 10 outside the tube to the various elements inside the vacuum chamber 20. The source 80-A typically includes a mount 30 that secures the vacuum chamber 20 within the housing 50, and the housing 50 prevents x-rays from being emitted in unwanted directions by the source 80-A. A shield material such as lead may be additionally provided.

  As described above, inside the chamber 20, the emitter 11 connected to the high voltage source 10 through the conductive wire 21 functions as a cathode, and in many cases, a current is passed through the filament to generate a beam of electrons 111. Any number of prior art techniques for electron beam generation can be used in the embodiments of the invention disclosed herein. Further known techniques used for electron beam generation are heating for thermionic emission, Schottky emission (combination of heating and field emission), multiple emitters with nanostructures such as carbon nanotubes, multiple ferroelectrics Using body material. [For more information on electron emission options for electron beam generation, see Shigehiko Yamamoto, Fundamental Physics of vacuum electron sources (Reports on Progress in Physics, Vol. 69, 181-232A, 6z, A). Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophonics (ISRN Nanomaterials, 2014 edition, paper number 879827, page 23 (2014)). Riege, "Electron emission from Ferroelectrics-A Review" (CERN Report CERN AT / 93-18, Switzerland / Geneva, July 1993)].

  As described above, the target 1100 having the target substrate 1000 and the region 700 of the X-ray generating material is electrically connected to the opposite high-voltage conductive wire 22 and the target support portion 32 which are low voltage, and thereby serves as an anode. . The electrons 111 are accelerated toward the target 1100 and collide with the target 1100 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of electrons 111 with the target 1100 causes multiple effects including the emission of X-rays. Some of the X-rays exit the vacuum tube 20 and pass through a window 40 that is transparent to the X-rays.

  However, in some embodiments of the present invention, an electrostatic lens system or a plurality of electrons controlled by controller 10-1 via lead 27 and coordinated with the electron dose and voltage provided by emitter 11 There may also be an electronic control mechanism 70 such as another system of lenses. Thus, the electron beam 111 is scanned, focused, defocused, or on a target 1100 having one or more microstructures 700 manufactured in intimate thermal contact with the substrate 1000, or Otherwise it can be directed.

  As illustrated in FIG. 7, the arrangement of the microstructures 700 is such that the impact of the plurality of microstructures 700 by the electron beam or the beam 111 is intensity in the viewing direction in a direction perpendicular to the surface normal of the target. May be arranged to cause release in a manner that increases or accumulates. That direction can also be selected by an opening 840 in the system screen 84 to form a directional beam 888 that exits the system through the window 40. In some embodiments, the opening 840 can be located outside the vacuum chamber, or more generally, the window 40 itself can serve as the opening. In some embodiments, the opening can be inside the vacuum chamber.

  A target such as that used in the X-ray source according to the present invention disclosed herein is a co-pending US patent application entitled “Structure Target for X-ray Generation (STRUCTURED TARGETS FOR X-RAY GENERATION)” (US patent application Ser. No. 14 / 465,816, filed Aug. 21, 2014), the contents of which are hereby incorporated by reference in their entirety and are included as Appendix A. Any target design and configuration disclosed in the above referenced copending application may be considered for use as a component of any X-ray source or all X-ray sources disclosed herein.

  FIG. 8 shows a target that may be used in some embodiments of the present invention. In this figure, a substrate 1000 has a region 1001 having an array of microstructures 700 including an X-ray generating material (typically a metal material) arranged in a regular array structure of right square pillars. In vacuum, the electrons 111 impact the target from above and generate heat and X-rays in the microstructure 700. The material of the substrate 1000 has a relatively low energy deposition rate for electrons compared to the material of the X-ray generating microstructure (typically selecting a low atomic number material for the substrate) Does not generate large amounts of heat and x-rays. The material of the substrate 1000 can also be selected to have a high thermal conductivity, typically greater than 100 W / (m ° C.), with the microstructure typically embedded within the substrate. That is, when the microstructure is formed as a quadrangular prism, at least five of the six surfaces are in close contact with the substrate 1000 so that heat generated in the microstructure 700 is effectively dissipated to the substrate 1000. It is preferable to have a mechanical contact. However, targets used in other embodiments may have fewer direct contact surfaces. In general, when the term “embedding” is used in this disclosure, at least half of the surface area of the microstructure is in intimate thermal contact with the substrate.

  The target 1100 according to the present invention can be mounted in place of the target 01 for the transmission X-ray source 08 illustrated in FIG. 1 or the target 100 illustrated in the reflection X-ray source 80 of FIG. It can be adapted for use as the target 500 used in the rotating anode x-ray source 580.

  It should be noted here that when the word “microstructure” is used herein, it specifically represents a microstructure with an X-ray generating material. Other structures, such as cavities used to form X-ray microstructures, can also be considered “microstructures” because they have the same scale dimensions. However, as used herein, other words such as “structure”, “cavity”, “hole”, “opening”, etc., refer to these in materials such as substrates that are not selected for their X-ray generation properties. Can be used in these structures. The word “microstructure” is reserved for structures having materials selected for these X-ray generation properties.

  Similarly, the term “microstructure” is used, but X-ray generating structures having dimensions smaller than 1 micron, or even smaller, nanoscale dimensions (ie, greater than 10 nm) are also used herein as “ It should be noted that it can be explained by the word “microstructure”.

  FIG. 9 illustrates another target as may be used in some embodiments of the present invention, where the electron beam 111-F is directed by an electrostatic lens to form a more concentrated focused spot. To do. In this situation, the target 1100-F still has a region 1001-F having an array of microstructures 700-F containing X-ray material, but the size and dimensions of this region 1001-F cause electron irradiation. Can match the region. In these targets, the “tuning” of the source shape and x-ray generating material can be controlled by the design to limit the amount of heat generated to the microstructure region 1001-F and also reduce design and manufacturing complexity. . This can be particularly useful when used with an electron beam that is focused to form a microspot, or when used by more complex systems that form more complex electron illumination patterns.

  FIG. 10 illustrates another target as may be used in some embodiments of the present invention, where target 1100-E emits X-rays when exposed to electrons 111. Still have an area 1001-E having an array of microstructures 700-E, including, but the area 1001-E is coplanar with or near the edge of the substrate 1000-E Placed in. This configuration can be useful with targets where emission at an angle close to 0 ° can be significantly attenuated in the configuration because the substrate has a material that absorbs x-rays, as shown in FIG.

  However, the disadvantage of the target of FIG. 10 is that a significant portion of the substrate is missing on one side of the microstructure 700-E as compared to FIG. Thus, heat is not removed symmetrically from the microstructure, local heating is increased, and heat flow can be exacerbated.

  To address this issue, some targets, such as those used in some embodiments of the present invention, may use a configuration as shown in FIG. Here, the target 1100-R has a substrate 1000-R having a shelf-like recess 1002-R. Thereby, the region 1001-R having the arrangement of the microstructures 700-R is arranged in the same plane as or close to the recessed edge 1003-R of the substrate, and 0 ° or 0 Although it is possible to emit X-rays at an angle close to 0 ° without being reabsorbed by the substrate 1000-R, it is still more symmetric with respect to the heat generated when exposed to the electrons 111. I will provide a.

  FIG. 12 shows the associated interaction between the electron beam 111 and a target having a substrate 1000 and a microstructure 700 of X-ray material. As illustrated, only three electron paths are shown, with two representatives of the electrons impacting the two microstructures 700 shown, one interacting with the substrate.

As discussed in Equation 1 above, the depth of penetration can be estimated by Pot's law. Using this equation, Table 2 shows some of the estimated penetration depths for some common X-ray target materials.

  In the example of FIG. 12, when 60 keV electrons are used, diamond (atomic number 6) is selected as the material of the substrate 1000, and copper (atomic number 29) is selected as the X-ray generating material of the microstructure 700, The size marked with R on the left side of 12 corresponds to a reference dimension of 10 microns, and the depth D of the X-ray generating material was set to 2/3 (66%) of the electron penetration depth for copper. Sometimes it becomes about 3.5 microns.

  Most of the characteristic X-rays (K-rays) of Cu are generated within the depth D. Electron interactions below that depth typically generate little characteristic X-rays (K-rays), but contribute to heat generation, which creates a gentle temperature gradient along the depth direction. Bring. Thus, in some embodiments, it is preferable to set the maximum thickness of the microstructure in the target to limit the interaction of electrons in the material and optimize the local temperature gradient. One embodiment of the present invention limits the depth of the microstructured X-ray generating material in the target to between 1/3 and 2/3 of the electron penetration depth at the incident electron energy. In this case, the lower mass density substrate results in a lower energy deposition rate for the substrate material immediately below the x-ray generating material, which in turn results in a lower temperature for the underlying substrate material. This provides a greater temperature gradient between the X-ray generating material and the substrate, increasing heat conduction. The temperature gradient is further magnified by the high thermal conductivity of the substrate material.

  For the same reason, selecting the depth D to be shallower than the electron penetration depth is generally preferable for efficient generation of bremsstrahlung. This is because electrons below that depth have lower energy and hence lower x-ray generation efficiency.

  Note: Other options for x-ray generating material dimensions may also be used. For targets such as those used in some embodiments of the present invention, the depth of the x-ray material can be selected to be 50% of the electron penetration depth. In other embodiments, the depth of the x-ray material can be selected to be 33% of the electron penetration depth. In other embodiments, the microstructure depth D may be selected in relation to the “continuous deceleration approximation” (CSDA) range of electrons in the material. Other depths can be specified depending on the desired x-ray spectrum and the properties of the selected x-ray material.

  Note: For other targets, such as may be used in some embodiments of the invention, a specific ratio between the depth and lateral dimensions (such as width W and length L) of the x-ray generating material may also be specified. . For example, if the depth is selected to be a certain size D, then the lateral dimensions W and / or L are selected to be less than 5 times D, giving a maximum ratio of 5. In other targets, such as may be used in some embodiments of the present invention, the lateral dimensions W and / or L may be selected to be no more than twice D. The depth D and the lateral dimensions W and L (width and length of the X-ray generating microstructure) can be defined relative to the axis of electron propagation or can be defined relative to the orientation of the surface of the X-ray generating material. It should also be noted. For normally incident electrons, these are the same dimensions. Care must be taken to ensure that proper prediction is used for obliquely incident electrons.

  FIG. 13 shows the relative x-ray generation from the various regions shown in FIG. X-rays 888 have characteristic X-rays emitted from regions 248 in the X-ray generating material from which they generate, and regions 1280 and 1080 where electrons interact with the substrate generate characteristic X-rays for the substrate elements. (It is not the characteristic X-ray of the element of the X-ray generation material in the X-ray generation region 248). In addition, the bremsstrahlung x-rays emitted from the region 248 of the x-ray generating material are typically weak continuous x-rays emitted by those regions in regions 1280 and 1080 where the electrons only encounter a low atomic number substrate. Much stronger than lines 1088 and 1228.

  The illustration of FIG. 13 shows X-rays that are emitted only to the right, which is placed to the right when this target is used in the low angle high brightness configuration discussed in FIGS. 5A-5C. It should be noted that this is because we are expecting a window or collector. In practice, x-rays are typically emitted from these regions in all directions.

  As FIG. 13 shows a configuration that allows the linear accumulation of characteristic X-rays along the microstructure and thus can generate a relatively strong characteristic X-ray signal, multiple materials can be used with respect to their own characteristic X-rays. It should also be noted that it is relatively transparent. However, many lower energy x-rays are attenuated by the target material that effectively acts as an x-ray filter. Multiple materials and other multiple choices of geometric parameters are non-characteristic, such as in applications where low energy x-ray bandpass is desired (eg, for image processing or fluorescence analysis of low atomic number materials) Can be selected (e.g., non-linear method) when continuous X-rays are desired.

  Up to this point, targets arranged in a planar structure have been shown. These are generally easier to implement. Because equipment and process recipes for multiple steps of deposition, etching, and other planar processes include processing of devices for microelectromechanical system (MEMS) applications using planar diamond, and silicon wafers for the semiconductor industry. This is because it is well known in processing.

  However, in some embodiments, a target with a surface having additional properties in three dimensions (3-D) may be desired. As previously discussed, when the electron beam is larger than the electron penetration depth, the apparent x-ray source size and region is parallel to the surface, ie when viewed at an extraction angle of zero degrees (0 °). Minimized (and brightness maximized). As a result, an apparent maximum luminance X-ray emission occurs when viewed at a 0 ° extraction angle. Emissions from within the x-ray generating material accumulate as it propagates through the material at 0 °.

  However, in a broad target of substantially uniform material, as the x-rays propagate through the material to the surface, the attenuation of the x-rays between multiple sources of x-rays within the target reduces the extraction angle. And increases due to the longer distance traveled within the material, often maximizing at or near an extraction angle of 0 °. Thus, any increase in brightness achieved by viewing near 0 ° can be balanced by reabsorption. The distance at which the X-ray beam decreases in intensity to 1 / e is called the X-ray attenuation length. Therefore, a configuration having a distance selected in relation to the x-ray attenuation length that does not allow the emitted x-rays to pass through as much further material as possible may be desired.

  An illustration of a target as may be used in some embodiments of the present invention is shown in FIG. In FIG. 14, an X-ray generation region having a single microstructure 2700 is configured at or near the recessed edge 2003 of the substrate in contact with the shelf 2002, similar to the situation illustrated in FIG. 11. doing. The X-ray generation fine structure 2700 has a rectangular bar shape made of an X-ray generation material, is embedded in the substrate 2000, and emits X-rays 2888 when bombarded with electrons 111.

  The bar thickness D (thickness along the surface normal of the target) is between 1/3 and 2/3 of the electron penetration depth of the X-ray generating material at the incident electron energy for optimum thermal performance. Selected. The thickness D of the bar can also be selected to obtain a desired X-ray source size in the vertical direction. The width W of the bar is selected to obtain the desired source size in the corresponding direction. As illustrated, W is approximately 1.5 times D, but can be substantially smaller or larger depending on the size of the desired source spot.

  As illustrated, the bar length L is approximately 4 times D, but can be of any size and is typically 1 / X of the x-ray attenuation length of the selected x-ray generating material. It can be determined to be between 4 and 3 times. As illustrated, the distance p between the edge of the shelf and the edge of the X-ray generating material is approximately equal to W, but the X-ray reabsorption characteristics, relative thermal characteristics, and electrons of the substrate material Depending on the amount of heat expected to be generated when an impact is applied, an arbitrary value may be selected from a point that is coplanar with the edge 2003 (p = 0) to a maximum of 1 mm.

  An illustration of an alternative target as may be used in some embodiments of the present invention is shown in FIG. In this target, an X-ray generation region having six microstructures 2701, 2702, 2703, 2704, 2705, 2706 is configured at or near the recessed edge 2003 of the substrate in contact with the shelf 2002, It is similar to the situation illustrated in FIGS. X-ray generation microstructures 2701, 2702, 2703, 2704, 2705, 2706 are arranged in a linear array of rectangular prisms that generate X-rays embedded in the substrate 2000, and when X-ray generation is impacted by electrons 111 Line 2888-D is emitted.

  In this target as may be used in some embodiments of the present invention, the total volume of x-ray generating material is the same as in the previous illustration of FIG. The same applies to the case shown in FIG. 14, but the bar thickness D (thickness along the surface normal of the target) is the electron penetration depth of the X-ray generating material at the incident electron energy for optimum thermal performance. It is selected to be between 1/3 and 2/3. As in the case shown in FIG. 14, the bar width W is selected to obtain the desired source size in the corresponding direction, and as illustrated, W is approximately 1.5 times D. is there. As discussed previously, the bar width W can be substantially smaller or larger depending on the size of the desired source spot.

  However, a single bar 2700 of length L as illustrated in FIG. 14 has been replaced with six subbars 2701, 2702, 2703, 2704, 2705, 2706, each having a length l of L / 6 It is. The volume of X-ray generation (when bombarded with the same electron density) is the same, but here each subbar has five faces that transfer heat to the substrate, and from X-ray generation subbars 2701-2706 Increase heat dissipation to the substrate. As illustrated, the separation distance d between the sub-bars is approximately equal to l, but larger or smaller dimensions may be used, which are the X-ray dose absorbed by the substrate and the X-rays Depends on the relative temperature gradient that can be realized between the particular material of the generated microstructure 2701-2706 and the substrate 2000.

  Similarly, the distance p between the edge of the shelf and the edge of the X-ray generating material is approximately equal to W as illustrated, but the X-ray reabsorption characteristics, relative thermal characteristics of the substrate material. Depending on the amount of heat expected to be generated when impacted by electrons, it may be chosen to be any value from where it is coplanar with edge 2003 (p = 0) to a maximum of 1 mm. .

  In the configuration shown in FIG. 15 and the like, the total length of the plurality of X-ray generation sub-bars is generally about twice as long as the X-ray linear attenuation length in the X-ray generation material. Can be selected. Similarly, the bar thickness D (thickness along the surface normal of the target) is equal to 1/3 to 2/3 of the electron penetration depth of the X-ray generating material at the incident electron energy for optimum thermal performance. Although selected to be, it can be substantially larger. The thickness D of the bar can also be selected to obtain a desired x-ray source size that is approximately equal in the relevant direction.

  The bars shown may be embedded in the substrate (as shown), but may be placed on the substrate if the thermal load generated on the x-ray generating material is not too great.

  FIGS. 16A-16C have an array of microstructures 700 in the form of rectangular prisms containing X-ray generating materials arranged in a regular array structure, as may be used in some embodiments of the present invention. A target region 1001 is shown. FIG. 16A shows a perspective view of the 16 microstructures 700 for this target, FIG. 16B shows a top view of the same region, and FIG. 16C shows a side / cross-sectional view of the same region. (For the term “side / cross-sectional view” of the present disclosure, the meaning figure is a view of creating a cross-section of an object and then looking at the surface of the cross-section from the side. It shows both the details of the cross-section and both the interior of the material that can be seen from the side, assuming that the substrate itself is transparent (in the case of diamonds, generally true for visible light).

  In these targets, the plurality of microstructures are fabricated so that they are in intimate thermal contact with the substrate on five of the six surfaces. As illustrated, the top surfaces of the plurality of microstructures 700 are coplanar with the surface of the substrate, but other targets with recessed microstructures may be fabricated, and the plurality of microstructures may be on the surface of the substrate. Other targets may be manufactured that exhibit local “bumps”.

An alternative target, such as may be used in some embodiments of the present invention, may have a plurality of rectangular prism microstructures simply deposited on the surface of the substrate. In this case, only the bottom surface of the prism can be in thermal contact with the substrate. In the case of a structure having a plurality of microstructures embedded in a substrate with a depth D and lateral dimensions W and L in the substrate plane, as shown in FIG. The ratio of the total surface area in contact with the substrate to the deposited microstructure is expressed as:
If the value of D is small relative to W and L, the ratio is substantially 1. As the thickness increases, the ratio increases, and in a cube where five equal surfaces are in thermal contact (D = W = L), the ratio is five. If a cap layer of material having similar properties to the substrate with respect to mass density and thermal conductivity is used, the ratio can increase to 6.

The heat conduction is illustrated by a typical arrow in FIG. 17, in which the heat generated in the plurality of microstructures 700 embedded in the substrate 1000 passes through the bottom surface and the plurality of side surfaces, and the plurality of microstructures 700. From the plane of the drawing to the outside (the arrows that propagate through the sides are not shown). The amount of heat conduction (ΔQ) per unit time transmitted through the material of area A and thickness d is given by the following equation.
Here, k is the thermal conductivity (W / (m ° C.)), and ΔT is the temperature difference (° C.) over the entire thickness d. Thus, an increase in surface area, a decrease in thickness, and an increase in ΔT all lead to a proportional increase in heat conduction.

  FIGS. 18A-18C illustrate a region 1013 of a target having a checkered array of microstructures 700 and 701 in the shape of a rectangular prism containing an X-ray generating material, according to one embodiment of the present invention. . The array as shown is arranged as a buried array on the surface of the substrate. 18A shows a perspective view of 25 buried microstructures 700 and 701, FIG. 18B shows a top view of the same region, and FIG. 18C shows a side / sectional view of the same region with a recessed region indicated by a dotted line. ing.

  An illustration of another target, such as may be used in some embodiments of the present invention, is shown in FIGS. 19A-19C, which shows an array of microstructures 2790 and 2791 that include an X-ray generating material having a thickness D. FIG. 2 shows a target region 2001 according to an embodiment of the invention. The arrangement shown is a modified checkered pattern of rectangular prisms, but other configurations and arrangements of multiple microstructures may be used.

  The same applies to targets used in other embodiments, but these microstructures 2790 and 2791 are embedded in the surface of the substrate. However, the surface of the substrate has a predetermined non-planar topography, in this particular case, a plurality of steps along the surface normal of the substrate 2000. As illustrated, the height h of each step is approximately equal to D, but the step height can be selected to be between 1 and 3 times the thickness of the plurality of microstructures. The total height of all steps can be selected to be equal to or smaller than the desired x-ray source size along the vertical direction (thickness direction).

  The total width of the microstructure region can be equal to the desired x-ray source size in the corresponding direction. The overall appearance resembles an X-ray source staircase. 19A shows a perspective view of 18 buried microstructures 2790 and 2791, FIG. 19B shows a top view of the same region, and FIG. 19C shows a side / sectional view of the same region. When the substrate is beryllium, diamond, sapphire, silicon, or silicon carbide, an electrically conductive layer can be coated on the top surface of the step structure.

  FIG. 20 shows X-ray emission 2888-S from the step target of FIG. 19C when impacted by electrons 111. FIG. The same applies to a plurality of targets used in other embodiments, but the plurality of prisms of the X-ray generating material are heated when electrons collide. Since each of the plurality of prisms of the X-ray generating material has five surfaces that are in thermal contact with the substrate 2000, the conduction of heat from the X-ray material is caused by the X-ray material on the surface. Still larger than the deposited composition. However, for one surface, x-ray emission is not attenuated by absorption by other adjacent prisms, but is negligibly attenuated by adjacent substrate material.

  Thus, the brightness of the X-rays from each prism is compared to the X-ray emission from the targets of FIGS. 18A-18C, which also shows a plurality of prisms 700 and 701 of X-ray generating material, particularly arranged in a checkered pattern. Sometimes increases. In the configuration of FIGS. 18A-18C, each prism is embedded in the substrate and thus has five surfaces in thermal contact with the substrate 1000, but the lateral emission at 0 ° is It is attenuated by both the prisms in the adjacent rows and the substrate material.

  One such embodiment comprising a target with topography first prepares the substrate with topography and then embeds multiple prisms of X-ray material according to the planar substrate manufacturing process described previously. Can be manufactured. Alternatively, the initial steps of forming cavities filled with x-ray material can be enhanced to form a stepped topographic structure on the initial flat substrate. In either case, additional registration steps, such as known to those skilled in the planar process, are used when it is desired to overlay the embedded prism with a particular feature topography. obtain.

  The plurality of microstructures may be embedded at a distance from the edge of the staircase as illustrated in FIGS. 19A-19C and 20, or (as shown in FIG. 10) the edge and It can be embedded in the same plane. The determination of which configuration is appropriate for a particular application can depend on the exact properties of the x-ray generating material and the substrate material, such as transfer of heat by, for example, five or four surfaces. The additional brightness realized by the increase in electron current made possible by the can be compared with the additional brightness realized by free space emission or reabsorption through a part of the substrate material. The additional costs associated with the alignment and superposition steps, and the multiple process steps that may be required to create multiple prisms in multiple layers, are considered relative to the increase in brightness that can be achieved. There may be a need.

  As described in US patent application Ser. No. 14 / 465,816 above, other target configurations that can be used in embodiments of the present invention include a plurality of microstructures having a plurality of X-ray generating materials. A plurality of microstructures having an alloy of X-ray generating materials, a plurality of microstructures having a diffusion prevention layer or an adhesion layer deposited thereon, a plurality of microstructures having a thermal conductive overcoat film, a thermally conductive and conductive overcoat A plurality of microstructures having a film, a plurality of microstructures embedded in a substrate, and the like.

  As described in US patent application Ser. No. 14 / 465,816 above, other target configurations that may be used in embodiments of the present invention are micron on a thermally conductive substrate such as diamond or sapphire. Multiple fines that may have any number of conventional X-ray target materials (such as copper (Cu), molybdenum (Mo), and tungsten (W)) that are patterned (or embedded) in scale-sized shapes An array of structures. In some embodiments, the plurality of microstructures alternatively has been limited in its use due to poor thermal properties, such as tin (Sn), sulfur (S), titanium (Ti), It may have a different X-ray target material such as antimony (Sb).

  As described in US patent application Ser. No. 14 / 465,816 above, other target configurations that may be used in embodiments of the present invention include cubes, rectangular blocks, regular prisms, rectangular prisms, Trapezoidal pillars, spheres, oval, barrel objects, cylinders, triangular prisms, pyramids, tetrahedrons, or surface textures or structures that increase surface area to generate the most intense X-rays and dissipate heat efficiently An array of multiple microstructures taking any number of geometric shapes, such as other specially designed shapes including shapes having

  As described in US patent application Ser. No. 14 / 465,816 above, other target configurations that may be used in embodiments of the present invention include aluminum, titanium, vanadium, chromium, manganese, iron, Cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and An array of a plurality of microstructures having various materials as X-ray generating materials, including combinations thereof and alloys thereof.

  The embodiments described so far have various X-ray target configurations with multiple microstructures having X-ray materials that can be used as targets for X-ray sources that generate X-rays with increased brightness. Contains. Although these target configurations have been described as emitting X-rays when bombarded with electrons, they are used as fixed X-ray targets in other conventional sources to target 01 of the transmission X-ray source 08 of FIG. Alternatively, either one of the targets 100 of the reflective X-ray source 80 of FIG. 2 may be replaced with a microstructure target that forms an X-ray source according to embodiments of the present invention.

  The multiple targets described above are embedded in a movable X-ray target, for example, forming the target 500 of the rotating anode X-ray source 80 of FIG. 6A with the movable microstructure target according to other embodiments of the present invention. Therefore, it is possible to replace the microstructure target as described above.

2. General Considerations for Linear Cumulative X-ray Sources FIG. 21 shows a collection of X-ray emitters arranged in a linear array. The long axis of the linear array extends from left to right in the figure, and the short axis extends in and out of the plane of the figure. A plurality of X-ray generating elements 801, 802, 803, 804,. ,..., Etc. are applied to form a sub-source that emits X-rays 818, 828, 838, 848,. Although X-rays tend to be emitted isotropically, the analysis here is for a viewpoint along an axis through the center of the linear array of sub-sources, where a screen 84 having an opening 840 is present. Has been placed.

  As depicted in FIG. 21, the aperture allows X-rays with a cumulative angle of 0 ° to emerge from the source, but in practice, +/− 3 ° relative to the surface normal or It should be noted that openings that allow multiple angles of emission x-rays that are also emitted at +/− 6 ° can be designed for use in some applications. Although it is generally preferred that the window be at or near normal incidence with respect to the long axis of the linear array, in some embodiments, a window inclined at an angle of up to 85 ° may be useful.

  Assuming that the i th emitter 80i emits x-rays 8i8 along the axis to the right side of FIG. 21, as illustrated, the emission for the rightmost emitter is simply to the right through free space. Propagate. However, x-rays from other emitters are attenuated through any absorption, scattering, or other loss mechanisms that occur while passing through any material between the emitters. It is also attenuated by divergence from the propagation axis and losses caused by passing through adjacent emitters.

If defined as follows: I _i : X-ray emission intensity 8 i 8 from the i-th emitter 80 i, T _1,0 : X-ray transmittance for right propagation of the first emitter 801, T _{i, i-1:} i-th emitter from 80i (i-1) th emitter 80 X-ray transmittance on propagation of (i-1) _{to, T} i: X-ray relates propagation through the i-th emitter 80i Transmittance (T ₀ is 1), the total intensity of the X-ray on the axis to the right from the array of N emitters is expressed as:
This finally becomes:

In a source design where all emitters emit X-rays of approximately the same intensity,
(This can be achieved if the array of X-ray emitting elements are of similar size and shape and are bombarded with electrons having similar energy and density). The total emission intensity is:

Furthermore, if the multiple emitters are arranged in a regular array structure having substantially the same value for transmission between the multiple elements, then:
If the sizes and shapes of the plurality of X-ray emitting elements are sufficiently similar so that the propagation through any given element is the same, the following equation is obtained.
Next, the total emission intensity is as follows:

Note that T _i and T _{i, i−1} represent the attenuation of the propagation due to loss and therefore always have a value between 0 and 1. When N is large, the sum of the right side can be approximated by a geometric series and is expressed by the following equation.
As a result, the approximate strength is as follows.
This equation suggests that I _tot is increased by bringing the product of the transmittances T ₁ and T _2,1 as close to 1 as possible.

Note that this can also be used to estimate how many emitting elements can be placed in a row before the addition of another X-ray emitting element is wasted due to loss and attenuation. For example, if the width of the emitting element is 1 / e of the attenuation length of X-rays, the transmittance of the element is T ₁ = 1 / e = 0.3679. Assuming that the transmittance between the elements is T _{i, i-1} = T _2,1 = 0.98, the following equation is derived.
This formula suggests that a large number of elements having a width equal to the length of 1 / e can only improve the strength by 1.564 times. It suggests that it is less productive on the axis.

For example, for thinner elements with X-ray attenuation of T ₁ = 0.80,
This formula suggests that up to approximately five of these elements can be arranged in a row to form a source as bright as a source with multiple x-ray generating elements.

It should be noted that the x-ray attenuation is different for different energy x-rays, and the product of T ₁ and T _2,1 can vary significantly over a range of wavelengths for a given material.

FIG. 22 shows the 1 / e attenuation length for three types of X-ray generating materials, namely, molybdenum (Mo), copper (Cu), and tungsten (W) for X-rays having energy ranging from 1 keV to 400 keV, and three types of substrate materials. That is, the 1 / e decay length for X-rays having energy in the range of 10 keV to 400 keV of graphite (C), beryllium (Be), and water (H ₂ O) is shown. [The data shown here was originally L. Henke, E.M. M.M. Gullikson, J. et al. C. According to Davis, “X-ray interactions: photoabsorption, scattering, transmission, and reflection at E = 50-30000 eV, Z = 1-92”, Atomic Data and Nuclear 2 pages 34-34. (July 1993), <http: // henke. lbl. gov / optical_constants / atten2. It can be accessed at html>. Other X-ray absorption tables are <http: // physics. nist. gov / PhysRefData / XrayMassCoef / chap2. available at html>].

The 1 / e attenuation length L _{1 / e} of the material is related to the transmittance for the length L by the following equation:
Therefore, increasing L _{1 / e} means that T _i increases.

As an example using the values of FIG. 22, using a 60 keV X-ray of tungsten, approximately 200 microns of L1 _{/ e} , the transmittance of a 20 micron wide X-ray generating element is given by:
On the other hand, in the case of an L _{1 / e} beryllium substrate of approximately 50,000 microns, the transmittance of the tungsten X-ray generating element having a width of 100 microns embedded in beryllium is expressed by the following equation.
Thus, for a periodic array of 20 micron wide tungsten elements embedded in a beryllium substrate and spaced apart by 100 microns, the best estimate of on-axis strength is:
This represents an order of magnitude increase in x-ray intensity when compared to a single tungsten x-ray emitting element.

3. X-Ray Source Control There are a number of variables by which such a general linear accumulation source can be “tuned” or adjusted to improve the X-ray output. Embodiments of the present invention may allow control and adjustment of some or all of these variables, or do not control or adjust any of these variables.

3.1. Electron Beam Variations First, in some embodiments, the beam 111 or the plurality of beams such as 1111, 1112, 1113, etc. that impact the X-ray generating elements 801, 802, 803,. It can be formed and oriented using one or more electronic control mechanisms 70 such as lenses, electrostatic lenses, or magnetic field focusing elements. Typically, multiple electrostatic lenses can be placed in the vacuum environment of the x-ray source and multiple magnetic field focusing elements can be placed outside the vacuum. Disclosed in prior art REBL (Reflected Electron Beam Lithography System) as described in US Pat. No. 6,870,172, Maskless Reflection Electron Beam Projection Lithography Various other electronic image processing techniques, such as a reflected electron beam control system, can also be used to form complex patterns of electron irradiation.

  As illustrated in FIG. 21 and also illustrated in FIG. 23A, electrons can impact multiple elements at normal incidence, and electron beams 1121, 1122, 1123 as illustrated in FIG. 23B. Etc. is an angle θ, and as illustrated in FIG. 23C, electron beams 1131, 1132, 1133, etc. (such as a convergent electron beam) are at a plurality of angles, and as illustrated in FIG. The electron beams 1141, 1142, 1143, etc. that impact the beam are at an angle θ, and as illustrated in FIG. 23E, the electron beams 1151, 1152, 1153, etc. are at various intensities or electron densities, as illustrated in FIG. 23F. Multiple elements can be impacted with a uniform large area electron beam 111 or with any combination of many electron beam configurations that can be devised by those skilled in the art. The

  The actual design of the pattern for electron irradiation may depend in part on the material properties of the x-ray generating material and / or the material filling the region between the plurality of x-ray generating elements. As illustrated in FIG. 23E, when the X-ray generating material is very absorbent, it must emit X-rays and travel the longest distance through the other plurality of X-ray generating elements. Greater electron density can be used to impact the. Similarly, as illustrated in FIG. 23B, when the electron penetration depth is deep, the X-ray generation material can be bombarded with oblique electrons. If the electron penetration depth is deeper than desired, a thinner region of x-ray generating material can be used to form a source with a smaller vertical dimension.

  In many embodiments, the region of electron irradiation is such that the electron beam or plurality of electron beams primarily impacts the x-ray generating elements 1001, 1002, 1003, etc., and impacts the region between these elements. Can be adjusted to not. In many embodiments, the spacing between the plurality of x-ray generating elements may be filled with a solid material that facilitates heat dissipation from the plurality of x-ray generating elements, rather than a vacuum. Such a source target having an array of multiple x-ray generating elements embedded in or embedded in a thermally conductive substrate such as diamond is described in copending US patent application Ser. No. 14 / 465,816, as described above. Which is incorporated by reference in its entirety.

  If the area between the multiple X-ray generating elements has a solid material and is bombarded with electrons, the area tends to be heated under electron irradiation, thereby causing the multiple X-ray generating elements and The temperature gradient of the X-ray generation element is reduced, so that the heat flow from the X-ray generating element is reduced. The limitations on the amount of electron energy and density are often determined in part by the amount of energy that can be absorbed by the X-ray generating material before thermal damage such as melting occurs, resulting in multiple X-ray generating elements from It is generally preferred to increase heat dissipation, which can be achieved in part by reducing electron irradiation in non-X-ray generating regions. Since the heat generated by electron irradiation tends to increase as the atomic number Z increases, a substrate having a low atomic number material such as beryllium (atomic number 4) or diamond (atomic number 6) can be selected. It should be noted that there may be preferred cases.

  A source having multiple electron beams used to independently bombard separate multiple x-ray generating elements can also be configured to allow different acceleration voltages to be used with different electron beam sources. . Such a source 80-B is illustrated in FIG. Also in this example, the previous high voltage source 10 is connected to the electron emitter 11-A that emits the electrons 111-A toward the target 1100-B via the conductor 21-A. However, two additional “boosters” for voltages 10-B and 10-C are also provided, and these high potentials are passed through the conductors 21-B and 21-C to electrons of different energy 111-B and 111-B. Connected to additional electron emitters 11-B and 11-C emitting -C. The target 1100-B having X-ray generating elements 801, 802, 803,... Is usually set to a uniform ground potential, but individual electrons used to target different X-ray generating elements. The beam source can be set to different potentials, so that various energetic electrons can be used to impact different x-ray generating elements 801, 802, 803,.

  This can provide multiple advantages in managing X-ray emission in that electrons of different energies can generate different X-ray emission spectra depending on the material used for the individual X-ray generating element. The generated heat load can also be managed through the use of different electronic energy. For such multiple beam configurations, the design of multiple electron lenses to keep the various beams from interfering with each other and to not give wrong energy electrons to the wrong target element is complicated. Can be.

3.2. Material Variations It is easier to treat multiple x-ray generating elements as the same building block and to consider the multiple regions in between to be the same, but some embodiments have variations in these parameters There can be several advantages to this.

  In some embodiments, different x-ray generating elements may have different x-ray emitting materials, such as an axial view showing various spectral characteristic x-rays from different materials. A material that is relatively transparent to x-rays can be used in a position closest to the output window 840 (eg, the rightmost element in FIG. 21), but a material that absorbs more strongly can cause other sources to It can be used for elements on the opposite side of the array so as not to attenuate too much.

  In some embodiments, the distance between multiple x-ray generating elements can be varied depending on the anticipated thermal load of multiple different materials. For example, a wider spacing between multiple elements can be used for an element that is expected to generate more heat under electron bombardment, and a smaller spacing is expected if less heat is expected. Can be used.

3.3. Size and Shape Variations As illustrated in FIG. 25, in some embodiments, the x-ray generating elements 1801, 1802, 1803,... Can have various sizes and geometric shapes. This can be particularly useful in situations where a plurality of different materials are used and the electron deceleration process and x-ray absorption are different for a plurality of different materials.

Useful figures of merit that can be considered in the design of multiple x-ray generating elements for a linear cumulative x-ray source are the 1 / e attenuation length of x-rays in the material and the “continuous deceleration approximation” (CSDA) of electrons The ratio is half of the range. As an electron decelerates, the CSDA range of the electron is typically greater than the penetration depth, as multiple collisions can lose energy. FIG. 26A shows a diagram of these two functions for tungsten, and FIG. 26B shows a diagram of the ratio. X-ray data is from sources previously cited by Henke et al., And CSDA range data is from NIST “Physical Measurement Laboratory” <http: // physics. nist. gov / PhysRefData / Star / Text / ESTAR. html>. The ratio, when used for X-ray linear accumulation, can be considered a figure of merit for the X-ray generation of a material. It, X-rays transmittance of the material is large (that T _i is increased with respect to the microstructure) but the value is large when, because also increases when more CDSA flight is small (which electrons rapidly The x-rays appear to be emitted from shallower depth spots).

  FIG. 27 shows this ratio for a wide range of x-ray energies for the three materials (Cu, Mo, and W). Once the X-ray material is selected for the desired characteristic line, this ratio can be used to suggest a specific energy range (such as about 55 keV for tungsten), so that this figure of merit can be compared. The system can be configured to operate in such a state as to become large.

  As a rule of thumb, the thickness of the microstructure can be set to 1/2 or less of CSDA as measured in the direction of electron beam propagation. In some selections of target materials, the thin foil coating material may be sufficient to provide the required x-ray emission, and more complex embedded or embedded microstructures may not be required.

3.4. Time-Division Emission In other embodiments, the X-ray generating elements 801, 802, 803, 804,... Do not need to be continuously impacted by electrons, but the electron beams 1211, 1212, 1213, 1214, Etc. can be switched on and off over time to distribute the heat load. This can be particularly effective when viewed on an axis. This is because all X-rays appear to be emitted from the same source.

  One time division embodiment is illustrated in FIGS. 28A-28C. In FIG. 28A, at the first time step t = 0, electron beams 1211 and 1214 for elements 801 and 804 are on, respectively, and everything else is off. In FIG. 28B, at time step t = 1, electron beams 1212 and 1215 for elements 802 and 805 are on and all others are off. In FIG. 28C, at the next time step t = 2, the electron beams 1213 and 1216 for elements 803 and 806 are on and all others are off. The system simply makes the various electron beams invisible between these configurations, or simply blocks them with a mechanical shutter or changes the position of these electron beams. Can be switched.

  Furthermore, in some embodiments, the electron beam may simply scan across the target with the x-ray generating material. In some embodiments, this scan may be a regular raster scan, and in other embodiments, the scan may be “dwelled” or the x-ray generation area may be scanned at a slower rate. On the other hand, non-uniform scanning such as rapid movement from one X-ray generation region to the next X-ray generation region may be used. In other embodiments, the electron beam can be designed to bombard all x-ray generation regions simultaneously, or the plurality of electron beams impinge on the plurality of x-ray generation regions almost simultaneously, It can be turned on and off rapidly to form a “pulsed” x-ray source. This can have several advantages for some specific applications.

  Sources that can change the timing of electron irradiation use multiple different types of embedded microstructures that can be bombarded with multiple different potential electrons to emit various spectral x-ray energies, as described above. Multiple embodiments may also be particularly useful.

3.5. Off-axis configuration In other embodiments, a slightly off-axis configuration may be preferred. Several examples of such a configuration are illustrated in FIGS. 29A-29B.

  In FIG. 29A, X-ray emission is illustrated through an off-axis window 841, or an opening in the screen 84 or wall. Since X-ray emission is generally isotropic, emissions from all microstructures impacted by electrons are also emitted in this direction. However, the various rays of this emission 878 that pass through the opening 841 are dispersed without propagating in the same direction, presenting an expanded source appearance. However, if an extended source aspect is desired, a small angle aggregate configuration for X-rays using such off-axis may be appropriate.

  FIG. 29B shows emission from a plurality of microstructures, this time away from the incident electron beams 1111, 1112, 1113, and the like. In this embodiment, the spacing of the microstructures 801, 802, 803,... Is much larger than their size so that X-rays can be detected by the detector without attenuation by adjacent X-ray emitting elements. The off-axis angle is much smaller than the off-axis angle in the situation illustrated in FIG. 29A.

3.6. Multiple Independent Electron Beams Illustrated in FIGS. 30 and 31 (the target is shown in more detail) is a more general X-ray system 80 that incorporates some of the elements described above. -C. The system includes a plurality of electron emitters 11-A, 11 that generate electron beams 111-A, 111-B, 111-C, etc. via a plurality of conductors 21-A, 21-B, and 21-C. The electronic system controller 10-V which sends various voltages to -B and 11-C is provided. Each of these electron beams 111-A, 111-B, and 111-C is connected to a plurality of electron lenses 70-A, 70-B, and 70 via conductors 27-A, 27-B, and 27-C. It can be controlled by a signal from the system controller 10-V that controls -C.

  As illustrated, the system further comprises a cooling system. The cooling system includes a container 90 filled with a cooling fluid 93, typically water, which includes a plurality of cooling paths that pass through a substrate 1000 of a target 1100-C by a mechanism 1209 such as a pump. It is moved through the cooling path 1200.

  It should be noted that these illustrations are presented for the purpose of assisting in understanding the present invention, and that various elements (microstructures, surface layers, cooling paths, etc.) are not drawn to scale.

  FIG. 31 shows a target 1100-C under electron impact in an enlarged view of the system, in which two additional electron beams 111-D and 111-E have been added. As illustrated, both beams 111-D and 111-E have a higher current than the right three electron beams 111-A, 111-B, and 111-C, and the leftmost electron beam 111 -E has the highest current density of all the beams, indicating that the beams need not be of equal density. The leftmost X-ray generating elements 804 and 805 that receive a higher current are between these and the adjacent microstructure, between the rightmost elements 801, 802, and 803 that receive a lower electron current. It is also illustrated that it has a larger interval than that provided in FIG. In some embodiments, 804 and 805 can be composed of a material with a higher atomic number than 801, 802, and 803.

  FIG. 31 also shows a conductive overcoat film 770 that serves both as thermal conductivity (to remove heat) and conductivity, and is provided with a return path for electrons to the ground 722. A screen 84 is also provided having an opening 840 to allow on-axis x-rays to be emitted from the target.

3.7. Selection of Material for Substrate As described above, in the target substrate having a plurality of fine structures of the X-ray generating material, the X-ray transmittance T to the substrate is preferably about 1. For a substrate material having a length L and a linear absorption coefficient α _s , the following equation is obtained.
Here, L _{1 / e} is a length at which the X-ray intensity decreases to 1 / e times.

Generally, it is expressed by the relationship of the following formula.
Here, X is X-ray energy (keV), and Z is an atomic number. Therefore, to increase L _{1 / e} (ie, to make the material more transparent), higher X-ray energy is required, and a lower atomic number is highly preferred. For this reason, both beryllium (atomic number 4) and carbon (atomic number 6) in various forms (eg, diamond, graphite, etc.) may be desirable as substrates. This is due to both reasons that they are very transparent to X-rays and also because of their high thermal conductivity (see Table 1).

4). Other Examples of Embodiments of the Invention 4.1.2 Target of One Surface One embodiment of a source 80-D using a target having a plurality of x-ray generating elements arranged for line accumulation 32, the target 2200 is shown in more detail in FIG.

  In the embodiment shown in FIG. 32, controller 10-2 supplies a high voltage to two emitters 11-D and 11-E that emit electron beams 1221 and 1222 toward both sides of target 2200. . The characteristics of the electron beams 1221 and 1222, such as the position, direction, and focusing, are adjusted via the conductors 27-D and 27-E, respectively. Controlled by D and 70-E, all controlled by controller 10-2. The target 2200 has a substrate 2200 and two thin coatings 2221 and 2222 of X-ray generating material, one on each side of the substrate 2200.

  The electron beams 1221 and 1222 are directed by a plurality of electron lenses 70-D and 70-E, and X-rays 821 and 822 generated from the respective positions are emitted from the source 80-D. The thin coatings 2221 and 2222 on both sides of the target 2200 are impacted in such a position that they are aligned with the openings 840 in the screen 84 that allow this.

  Large area bombardment with electrons achieves greater overlap, but higher electron emission occurs at higher electron densities, so that multiple electron lenses 70-D and 70-E are used for electron beams 1221 and 1222. Can be used to focus a small spot of 25 microns or even a smaller spot. For such a small spot in the configuration as shown, the location of two electron impact spots to generate a superimposed X-ray emission pattern (and thus to achieve a linear accumulation of the two spots) The alignment is performed by placing an X-ray detector over the aperture 840 and measuring the intensity of the X-ray beam 2888, and the position and focus of the electron beams 1221 and 1222 are determined by the plurality of electron lenses 70-D. And 70-E. Two spots can be considered aligned when the simultaneous intensity from both spots is maximized at the detector.

  The target 2200 can be securely attached to a structure in the vacuum chamber or can be attached so that its position can be changed. In some embodiments, the target can be mounted as a rotating anode to further dissipate heat.

  As described above, the thickness of coatings 2221 and 2222 may be selected based on expected electron energy and penetration depth or material CSDA estimate. As illustrated, the incidence angle can also affect the choice of coating thickness if the impact occurs at an angle to the surface normal. Although the tilt of target 2200 relative to electron beams 1221 and 1222 is shown at about 45 °, any angle from 0 ° to 90 ° that allows X-rays to be emitted may be used.

  It should also be noted that the two-surface target described above can also be used in one embodiment with a rotating anode in which the anode rotates to dissipate heat. A system 580-R having these features is illustrated in FIG. In this embodiment, many elements are the same as in a conventional rotating anode system as illustrated in FIG. 6A, but in this embodiment as illustrated, the controller 10-3 is connected to a conductor 21- A high voltage is supplied to two emitters 11-F and 11-G that emit electron beams 2511-F and 2511-G, respectively, via G and 21-F. These electron beams impact both sides of the chamfered portion of the target 500-R, coated on both sides with coatings 2521 and 2522 having an X-ray generating material that generates X-rays 2588. It should also be clear that multiple embodiments with additional controls may be designed, such as multiple electron lenses to steer the beam or openings to define the x-ray beam output.

4.2. Multiple Two Surface Targets Source 80-D as described above is not limited to a single target having two surfaces. Shown in FIG. 35 is a pair of targets 2203, 2204, each having two coatings 2231 and 2232, and 2241 and 2242, respectively, which are located on substrates 2230 and 2240, respectively. It is a line generating material. In this embodiment, four electron beams 1231 are now controlled to impact each of the plurality of coatings on the two targets 2203, 2204 and generate X-rays 831 and 832, and 841 and 842, respectively. Except for the presence of 1232, 1241, and 1242, the source has a configuration similar to that illustrated in FIG.

  In this embodiment, the four x-ray generation spots are aligned with the openings 840 in the screen 84 to appear to originate from a single source. The alignment procedure is 2 except that the four electron beams 1231, 1232, 1241, and 1242 are now adjusted to maximize the total x-ray intensity with the detector positioned beyond the aperture 840. As described above for the case of a two-surface target.

  As described above, targets 2203 and 2204 can be securely attached to structures in the vacuum chamber or can be attached so that their positions can be changed. In some embodiments, targets 2203 and 2204 can be mounted as rotating anodes to further dissipate heat. The rotation of targets 2203 and 2204 may be synchronized or controlled independently.

  As described above, the thickness of the coatings 2231, 2232, and 2241, 2242 can be selected based on expected electron energy and penetration depth or CSDA estimate of the material. As illustrated, the incidence angle can also affect the choice of coating thickness if the impact occurs at an angle to the surface normal. The tilt of the targets 2203 and 2204 relative to the electron beams 1231, 1232, and 1241, 1242 is shown at about 45 °, but any angle from 0 ° to 90 ° that allows X-rays to be emitted. Can be used.

  Although only two targets with four x-ray generating surfaces are illustrated in FIG. 35, multiple embodiments with any number of targets having multiple surfaces coated with x-ray generating material are the same. Used in a manner, each target can be impacted on one or both sides with an independently controlled electron beam. Further, the coatings for various targets can be selected to be different x-ray materials. For example, the upstream coatings 2241 and 2242 may be selected to be a material such as silver (Ag) or palladium (PD), and the downstream coatings 2231 and 2232 may be characteristic X generated from the upstream target. It can be selected to be rhodium (Rh), which has a higher transmission for the line. This can provide a mixed X-ray spectrum with multiple characteristic lines from multiple elements. Furthermore, adjustable x-ray mixing can be achieved by adjusting various electron beam currents and densities.

  Similarly, the coating itself need not be a uniform material, but may be an alloy of various x-ray generators designed to produce a mixture of characteristic x-rays.

4.3. FIG. 36 shows another embodiment, where the target has multiple microstructures of x-ray generating material embedded in a substrate instead of a thin coating. ing.

  Two targets 2301 and 2302 are shown (although a single target such as illustrated in FIGS. 32 and 33 may also be configured in this manner), each of four microstructures of X-ray generating material 2311, 2312, 2313, 2314, and 2321, 2322, 2323, and 2324, which are embedded in the surfaces of the substrates 2310 and 2320, respectively. The electron beams 1281, 1282, 1283, and 1284 are directed over the targets 2301, 2302 and appear to originate from the same source when aligned with the openings 840-B in the screen 84-B. X-rays are generated.

  As described above, the embedded microstructures for this embodiment may have different X-ray generating materials or alloys of X-ray generating materials to achieve the desired spectral output. Or it can have a mixture.

4.4. Another embodiment in which a plurality of position targets 2400 on an inclined surface is aligned with the distributed electron beam 2411 is illustrated in FIGS. 37A-37C. In this embodiment, the electron beam 2411 is focused on a plurality of spots on the coating 2408 of x-ray generating material formed on the substrate 2410. The electron beam 2411 is formed in a row in which multiple spots are aligned so that these x-ray emissions 2488 along the row (at an angle of 0 °) appear to originate from a single source. Can be adjusted.

  Variations of this embodiment are illustrated in FIGS. 38A-38C. In the target 2401 of this embodiment, the microstructures 2481, 2482, and 2483 of the X-ray generating material are embedded in the substrate 2410 instead of the coating. Dispersed electron beam 2411 impacts these microstructures and generates x-rays 2488 that also appear to originate from a single source.

5. X-Ray Concentration Using Additional X-Ray Lenses In the embodiments described so far, multiple X-ray emissions from multiple sources are generated when they are viewed from a particular angle. It is simply aligned so that it appears to overlap, and thus just appears to be a single brighter x-ray source.

  However, x-ray emission is generally isotropic and therefore, if an aperture with only a small viewing angle is used, most of the x-ray energy is lost.

  This can be addressed by collecting other x-rays emitted from multiple sources at other angles using multiple x-ray optical elements. A plurality of conventional optical elements for X-rays can be used, such as glazing angle mirrors, mirrors with multilayer coatings, or more complex Walter and capillary lenses.

  In general, the relationship between the target and the lens is established at the time of manufacture. The lens is fixed in place with either a specific mount or epoxy designed for use in vacuum, using alignment procedures such as are well known to those skilled in optical manufacturing. Can be done. As previously described, final alignment is achieved by placing an x-ray detector at the output aperture and adjusting the focus and position of the various electron beams to achieve maximum x-ray intensity. Can be realized. Final adjustments can also be made for alignment of multiple optical elements using X-rays. It should be noted that the detector can also be used to provide feedback to the electron beam controller. For example, the detector provides a measurement of the spectral output that can then be used to instruct the electron beam that generates a particular characteristic line to increase or decrease its output.

  It should also be noted that not all targets need to be illuminated with electrons of the same angle of incidence. In configurations having multiple x-ray emitting materials, different materials may have different penetration depths. Thus, bombarding with electrons of different angles of incidence can be more efficient for generating X-rays for that particular target. Also, as described in previous embodiments, different electron densities, energies, angles, focus states, etc. can be used for different targets.

  It should be noted that the emission occurs isotropically from all targets and that multiple x-ray lenses that collect and focus on the x-rays act on x-rays that propagate in both directions. Thus, a detector placed at the opposite end of the multiple target chain can serve as a monitor for the calibration and the overall output of the x-ray system.

5.1. General Reflective Lenses FIG. 39 illustrates one embodiment using three aligned targets 2801, 2802, 2803, each of which is a microscopic X-ray generating material embedded in a substrate 2811, 2812, 2813. Structures 2881, 2882, 2883 are included. Each of the plurality of targets is bombarded by electron beams 1181, 1182, and 1183, respectively, and generates X-rays 2818, 2828, and 2838, respectively.

  An X-ray imaging mirror lens 2821, 2822, 2831, 2832 is disposed between each of the plurality of X-ray emission targets, and collects X-rays emitted at a plurality of wider angles and is used as another X-ray. Redirect to the focal point at the position corresponding to the target x-ray generation spot. As illustrated, the focus is set to be the X-ray generation spot of the adjacent target, but in some embodiments, all X-ray mirrors have the X-rays at the same point, e.g., last Can be designed to focus on the last x-ray generation spot of the (rightmost) x-ray target.

  These imaging mirror lenses 2821, 2822, 2831, 2832 can be ellipsoidal mirrors with reflective surfaces typically made of glass, or surfaces coated with high mass density materials, or multilayer coated X-ray reflectors ( It may be any conventional x-ray imaging optical element, typically made with molybdenum (Mo) and silicon (Si) layers), or a crystal lens, or a combination thereof. The choice of materials and structure for the x-ray lens and its coating can depend on the spectrum of x-rays collected and refocused. Although illustrated as a cross-section, the entire x-ray lens or a portion thereof may have cylindrical symmetry.

  A modification of this embodiment is illustrated in FIG. In this embodiment, the first (upstream) X-ray target 2830 now includes a substrate 2833 embedded with a plurality of microstructures 2883 of X-ray generating material, as described elsewhere. Yes. The intensity of the X-ray 2838-A emitted from the target 2830 increases due to the linear accumulation of the X-rays emitted from the plurality of microstructures 2883, and in the previously described embodiments. Similarly, this embodiment can also contribute to a brighter overall x-ray source. However, in this embodiment, the electron beam 1183 -A has a different incident angle, size, shape, and shape (as illustrated) from the embodiment of FIG. 39 to effectively impact the plurality of microstructures 2883. And can be adjusted to have a focus.

  Another variation of this embodiment is illustrated in FIG. In this illustration, the second X-ray beam 2988-L propagating to the left is also illustrated. This second X-ray beam propagates through the second opening 840-L of the plate 84-L and can be used as a second X-ray irradiation source or used with the detector 4444, It can serve as a monitor for X-ray beam characteristics such as brightness, brightness, total intensity, flux, energy spectrum, beam profile, and divergence or convergence.

5.2. Walter Lens Another embodiment of the present invention is illustrated in FIG. In this embodiment, optical elements 2921 and 2931 that collect X-rays emitted from one target and focus it downstream in focus are optical elements now known as Walter lenses. A Walter lens is a well-known system of nested mirrors that collects and focuses X-rays, typically using parabolic and / or hyperbolic reflective surfaces, typically used at glazing angles, respectively. It has with the element of. Typically, the reflective surface is glass. The glass surface can be coated with a high mass density material or an X-ray multilayer (typically made using molybdenum (Mo) and silicon (Si) layers).

  43A and 43B show prior art embodiments of Walter lenses used for X-rays with various cylindrical lenses arranged in both horizontal and vertical directions. As mentioned above, the materials and coatings used for these optical elements can be selected to match the spectrum of x-rays expected to be emitted from various x-ray sources.

5.3. Capillary Lens Another embodiment of the present invention is illustrated in FIG. In this embodiment, the optical elements 2941 and 2951 that collect X-rays emitted from one target and focus it downstream in focus are optical elements now known as polycapillary lenses. Polycapillary lenses are similar to optical fibers in that X-rays are guided through a thin fiber and appear at the other end of the desired location. However, unlike optical fibers with solid glass fibers that reflect using total internal reflection, polycapillary lenses have multiple hollow tubes and X-rays are directed into the tube by external reflection from the material at the glazing angle. The

  A polycapillary lens is a well-known means for collecting and redirecting x-rays, and any number of conventional polycapillary optical elements can be used to implement multiple embodiments of the invention disclosed herein. It can be used in form. However, it is generally believed that polycapillary lenses with multiple capillary fibers can be used to collect X-rays emitted at many angles and direct them to the desired focal portion.

5.4. Variations Although specific options have been shown in several examples showing reflective lenses, Walter lenses, or capillary lenses, these are not meant to be limiting in any way. The optical configurations illustrated in FIGS. 39 to 42 and 44 may be interchangeable with, for example, a Walter lens 2931 that replaces the mirrors 2821 and 2822 of FIG. Multiple targets with multiple microstructures are used in these examples, but multiple targets with multiple thin films, such as illustrated in FIGS. 33 and 35, together with these X-ray lenses that focus at the focal point It should also be noted that it can be used.

6). Limitations and Extensions With the present application, a number of embodiments of the invention are disclosed, including the best mode contemplated by the inventors. While specific embodiments may be shown, it will be appreciated that elements discussed in detail only for some embodiments may be applied to other embodiments as well. .

  While specific materials, designs, configurations, and manufacturing processes have been shown to describe the present invention and preferred embodiments, such descriptions are intended to be limiting. is not. Variations and modifications may be apparent to those skilled in the art, and the invention is intended to be limited only by the scope described in the appended claims.

  Preferably, all elements, members, and processes described herein are included. As will be apparent to those skilled in the art, it is understood that any of these elements, members, processes can be replaced by other elements, elements, processes, or eliminated altogether. Should be.

  In general, this document discloses at least the following: A small source for generating high-intensity X-rays. Higher brightness is achieved by electron beam bombardment of multiple regions aligned with each other to achieve linear accumulation of X-rays. This is a novel with multiple microstructures of X-ray generating material made by aligning discrete X-ray emitters or in close thermal contact with a high thermal conductivity substrate. This is achieved by using an X-ray target. This allows heat to be more efficiently removed from the x-ray generating material and allows the material to be bombarded with higher electron density and / or higher energy electrons, Greater x-ray brightness is provided. The arrangement of multiple microstructures allows the use of on-axis convergence angles and allows the accumulation of x-rays from multiple aligned microstructures, so that it has a single source Visible, also known as “angle 0 °” x-ray emission.

This document also demonstrates at least the following concepts:
(Concept 1)
A vacuum chamber;
An X-ray transmissive window attached to the wall of the vacuum chamber;
At least one electron beam emitter in the vacuum chamber;
At least one target,
A substrate having a first selected material;
A plurality of discrete structures having a second material selected for its X-ray generation characteristics;
Said at least one target having
Prepared,
Each of the plurality of discrete structures is in thermal contact with the substrate,
At least one of the plurality of discrete structures has a thickness of less than 10 microns, and the lateral dimension of each of the at least one of the plurality of discrete structures is less than 50 microns;
X-ray source.
(Concept 2)
The plurality of discrete structures are embedded in the surface of the substrate.
X-ray source described in Concept 1.
(Concept 3)
The plurality of discrete structures are embedded within a depth of less than 100 microns on the surface of the substrate;
X-ray source according to concept 1 or 2.
(Concept 4)
Means for directing an electron beam emitted from the emitter onto the target;
The X-ray source according to any one of concepts 1 to 3.
(Concept 5)
The means for directing the electron beam comprises a plurality of electron lenses;
X-ray source according to concept 4.
(Concept 6)
The means for directing the electron beam comprises a plurality of electrostatic lenses;
X-ray source according to concept 4 or 5.
(Concept 7)
The means for directing the electron beam comprises a plurality of magnetic lenses;
X-ray source according to any one of concepts 4 to 6.
(Concept 8)
The above means for directing the electron beam include focusing, diverging, defocusing, scanning, raster scanning, pausing, hiding, sweeping, changing beam direction, beam Allows control of the electron beam by an operation selected from the group consisting of changing the intensity profile, forming multiple electron beams, changing the beam current density, and changing the acceleration of electrons in the electron beam. ,
X-ray source according to any one of concepts 4 to 7.
(Concept 9)
The means for directing the electron beam makes it possible to focus the electron beam on a spot size smaller than 30 microns in at least one dimension;
X-ray source according to any one of concepts 4 to 8.
(Concept 10)
The means for directing the electron beam enables directing the electron beam in a pattern corresponding to a position of at least a portion of the plurality of discrete structures;
The X-ray source according to any one of concepts 1 to 9.
(Concept 11)
The means for directing the electron beam enables directing the electron beam in a pattern corresponding to a position of at least a portion of the plurality of discrete structures;
The pattern is adapted in time in response to signals from a detector that monitors a plurality of predetermined characteristics of the emitted x-ray.
The X-ray source according to Concept 10.
(Concept 12)
The predetermined characteristics of the emitted X-ray are selected from the group consisting of brightness, brightness, total intensity, flux, energy spectrum, beam profile, and beam spread;
X-ray source according to concept 11.
(Concept 13)
The plurality of discrete structures are arranged in a linear array,
The X-ray source according to any one of concepts 1 to 12.
(Concept 14)
The plurality of discrete structures are manufactured to have similar shapes,
The X-ray source according to any one of concepts 1 to 13.
(Concept 15)
The similar shape is selected from the group consisting of a regular prism, a rectangular prism, a cube, a triangular prism, a trapezoidal pillar, a pyramid, a tetrahedron, a cylinder, a sphere, an egg, and a barrel.
X-ray source according to concept 14.
(Concept 16)
The first selection material is selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.
The X-ray source according to any one of concepts 1 to 15.
(Concept 17)
The second material is aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum Selected from the group consisting of tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
The X-ray source according to any one of concepts 1 to 16.
(Concept 18)
A subset of the plurality of discrete structures has a third material selected for its x-ray generation characteristics;
The X-ray source according to any one of concepts 1 to 17.
(Concept 19)
The third material is aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum Selected from the group consisting of tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
An X-ray source as described in Concept 18.
(Concept 20)
At least one of the plurality of discrete structures is disposed within 500 microns from an edge of the substrate;
The X-ray source according to any one of concepts 1 to 19.
(Concept 21)
The linear array is defined to have a major axis and a minor axis, the major axis of the linear array is aligned with the window, and the angle between the major axis and the surface normal of the window is Smaller than 85 ° at the intersection of the long axis and the window,
X-ray source according to any one of concepts 13 to 20.
(Concept 22)
At least one of the plurality of discrete structures is disposed within 500 microns from an edge of the substrate closest to the window;
X-ray source according to concept 21.
(Concept 23)
When the plurality of microstructures of the target are exposed to the directed electron beam, X-rays emitted by a predetermined one of the plurality of discrete structures are converted into the plurality of discrete structures. Aligned to penetrate another
X-ray source according to any one of concepts 4 to 22.
(Concept 24)
When the target is exposed to the directed electron beam, X-rays emitted by a predetermined number of discrete structures of the plurality of discrete structures are selected from the plurality of discrete structures. Aligned to penetrate one predetermined discrete structure;
The X-ray source according to any one of concepts 21 to 23.
(Concept 25)
A cooling system,
A container for storing the cooling fluid;
A path in the substrate for carrying the cooling fluid;
An additional path for transporting the fluid from the container to the path in the substrate;
An additional path for carrying the fluid from the path in the substrate to the container;
A pumping mechanism for pumping the fluid through the system;
Further comprising the cooling system comprising:
25. X-ray source according to any one of concepts 1 to 24.
(Concept 26)
A mechanism for rotating the target;
The X-ray source according to any one of concepts 1 to 25.
(Concept 27)
A vacuum chamber;
A first window transparent to X-rays attached to the wall of the vacuum chamber;
One or more electron emitters in the vacuum chamber;
Multiple X-ray targets
Prepared,
Each target has a material selected for its x-ray generation characteristics,
At least one size of the material is less than 20 microns,
The one or more electron emitters and the plurality of X-ray targets are aligned such that an electron impact on the plurality of targets generates a plurality of X-ray sub-sources, whereby the plurality of sub-sources are Aligned along an axis passing through the first window;
X-ray source.
(Concept 28)
The materials selected for their X-ray generation properties are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium Selected from the group consisting of silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
X-ray source according to concept 27.
(Concept 29)
For a predetermined X-ray energy spectrum, the transmittance of at least one of the plurality of X-ray targets is greater than 50%.
X-ray source according to concept 27 or 28.
(Concept 30)
The predetermined X-ray energy spectrum corresponds to an emission spectrum of at least one X-ray sub-source;
An X-ray source according to any one of concepts 27 to 29.
(Concept 31)
At least one of the plurality of targets further includes a substrate,
X-ray source according to any one of concepts 27 to 30.
(Concept 32)
The substrate has a material selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.
32. An X-ray source according to any one of concepts 27 to 31.
(Concept 33)
The X-ray generating material is on the substrate in the form of a thin film;
X-ray source according to concept 31 or 32.
(Concept 34)
The target has a plurality of discrete structures embedded in a substrate having a material with a thermal conductivity greater than 0.1 Wm ⁻¹ ° C ⁻¹ ,
The plurality of discrete structures have materials selected for their X-ray generation characteristics.
X-ray source according to any one of concepts 27 to 30.
(Concept 35)
Means for directing an electron beam from at least one of the plurality of electron emitters to one or more locations on the target to form a plurality of X-ray sub-sources;
X-ray source according to concept 34.
(Concept 36)
The means for directing the electron beam comprises a plurality of electron lenses;
X-ray source according to concept 35.
(Concept 37)
The central portion of all of the plurality of X-ray sub-sources generated by the impact of the plurality of electron beams to the plurality of targets is aligned along an axis passing through the first window. Means for aligning each of the plurality of electron beams;
37. An x-ray source according to any one of concepts 34 to 36.
(Concept 38)
At least two adjacent X-ray sub-sources share a common substrate;
38. X-ray source according to any one of concepts 27 to 37.
(Concept 39)
Further comprising an X-ray optical element;
The optical element is arranged such that X-rays emitted by a sub-source are directed by the optical element onto an adjacent X-ray sub-source.
X-ray source according to any one of concepts 27 to 38.
(Concept 40)
The X-ray optical element has a grazing incidence X-ray reflector,
X-ray source according to concept 39.
(Concept 41)
The X-ray optical element has an X-ray reflector with a multilayer coating;
X-ray source according to concept 40.
(Concept 42)
The x-ray optical element has a coated x-ray reflector having a thickness greater than 20 microns and comprising a high mass density material;
X-ray source according to concept 40.
(Concept 43)
The X-ray optical element has a Walter lens;
X-ray source according to concept 39.
(Concept 44)
The X-ray optical element has a polycapillary lens;
X-ray source according to concept 39.
(Concept 45)
The X-ray optical element has an elliptical capillary lens arranged such that a plurality of focal points correspond to the center of two adjacent sub-sources.
X-ray source according to concept 39.
(Concept 46)
Further comprising an X-ray optical element;
The optical element is arranged such that X-rays emitted by a sub-source enter the optical element and are directed over a predetermined position in the vacuum chamber.
X-ray source according to concept 39.
(Concept 47)
A second window transparent to x-rays attached to the wall of the vacuum chamber;
The plurality of sub-sources are aligned along a line passing through both the first window and the second window;
47. An X-ray source according to any one of concepts 27 to 46.
(Concept 48)
Further comprising an X-ray detector;
The detector is aligned such that the x-ray emitted by at least one of the plurality of sub-sources strikes the detector;
An x-ray source according to concept 47.
(Concept 49)
A vacuum chamber;
A first window transparent to X-rays attached to the wall of the vacuum chamber;
A first electron beam emitter in the vacuum chamber;
A second electron beam emitter;
A target,
A substrate,
A first structure having a material selected for its X-ray generation characteristics;
A second structure having a material selected for its X-ray generation properties;
Having a target,
Prepare
X-ray source.
(Concept 50)
Multiple pairs of electron beam emitters;
Multiple targets,
A substrate,
A first structure having a material selected for its X-ray generation characteristics;
A second structure having a material selected for its X-ray generation properties;
Having a plurality of targets,
In addition,
An x-ray source according to concept 49.
(Concept 51)
The material of the first structure and the material of the second structure are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium. Selected from the group consisting of ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
X-ray source according to concept 49 or 50.
(Concept 52)
The substrate has a material selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.
The X-ray source according to any one of concepts 49 to 51.
(Concept 53)
At least one of the plurality of structures is a thin film coating on a surface of the substrate;
53. An x-ray source according to any one of concepts 49 to 52.
(Concept 54)
The first structure and the second structure are both thin film coatings on both sides of the substrate.
An X-ray source according to any one of concepts 49 to 53.
(Concept 55)
At least one of the plurality of structures has one or more microstructures.
An x-ray source according to any one of concepts 49 to 54.
(Concept 56)
The one or more microstructures are embedded in the substrate;
An x-ray source according to concept 55.
(Concept 57)
One or more microstructures are embedded in an opposite surface of the substrate with respect to at least one of the other microstructures;
An x-ray source according to concept 56.
(Concept 58)
The first electron emitter and the second electron emitter are aligned to impact each of the surfaces of the target with a plurality of electron beams;
An x-ray source according to concept 49.
(Concept 59)
A method for generating X-rays,
Exposing at least one target to an electron beam formed to strike a plurality of discrete structures;
The at least one target is
A substrate having a first selected material;
A plurality of discrete structures having a second material selected for its X-ray generation characteristics;
Have
Each of the plurality of discrete structures is in thermal contact with the substrate,
At least one of the plurality of discrete structures has a thickness of less than 10 microns;
A lateral dimension of each of the at least one of the plurality of discrete structures is less than 50 microns;
Method.
(Concept 60)
A method for generating X-rays,
Exposing a plurality of targets having x-ray generating material contained within a single vacuum chamber with a plurality of electron beams;
The positions of the plurality of electron beams are adjusted to increase the intensity of the X-rays emitted from the plurality of targets and also passing through a predetermined opening.
Method.
[Appendix A]
Structured target for X-ray generation

  Appendix diagram 13 shows a region 1001 of a target according to one embodiment of the present invention having an array of microstructures 700 in the form of rectangular prisms containing X-ray generating material arranged in a regular array structure. . 13A of the appendix diagram shows a perspective view of 16 microstructures 700 of this embodiment, 13B of the appendix diagram shows a top view of the same region, and 13C of the appendix diagram shows a side / sectional view of the same region. Yes. (For the term “side / sectional view” of the present disclosure, the meaning figure is a view of creating a cross-section of an object and then looking at the surface of the cross-section from the side. And both the interior of the material that can be seen from the side, assuming that the substrate itself is transparent (in the case of diamonds, generally true for visible light).

  In this embodiment, the plurality of microstructures are fabricated to be in intimate thermal contact with the substrate on five of the six surfaces. As illustrated, the top surfaces of the plurality of microstructures 700 are coplanar with the surface of the substrate, but other embodiments in which the microstructures are recessed may be fabricated, and the plurality of microstructures may be formed on the substrate. Other embodiments may be manufactured that exhibit local “bumps” to the surface of the substrate.

Another embodiment may have a plurality of rectangular prism microstructures simply deposited on the surface of the substrate. In this case, only the bottom surface of the prism can be in thermal contact with the substrate. In the case of a structure having a plurality of microstructures embedded in a substrate having a depth D and lateral dimensions W and L in the substrate plane in the side / cross-sectional view as shown in Appendix C of 13C The ratio of the total surface area in contact with the substrate between the structure and the deposited microstructure is given by:
If the value of D is small relative to W and L, the ratio is substantially 1. As the thickness increases, the ratio increases, and in a cube where five equal surfaces are in thermal contact (D = W = L), the ratio is five. If a cap layer of material having similar properties to the substrate with respect to mass density and thermal conductivity is used, the ratio can increase to 6.

The heat conduction is illustrated by a typical arrow in 14A of the appendix diagram, in which the heat generated in the plurality of microstructures 700 embedded in the substrate 1000 is transmitted through the bottom surface and the plurality of side surfaces. Transmitted out of structure 700 (arrows transmitting through the sides in the out-of-plane direction of the drawing are not shown). The amount of heat conduction (ΔQ) per unit time transmitted through the material of area A and thickness d is given by the following equation.
Here, k is the thermal conductivity (W / (m ° C.)), and ΔT is the temperature difference (° C.) over the entire thickness d. Thus, an increase in surface area, a decrease in thickness, and an increase in ΔT all lead to a proportional increase in heat conduction.

  Another embodiment is illustrated in appendix 14B, where the substrate may additionally have a cooling path 1200. Such a cooling path may be a prior art cooling path using water or another cooling fluid to remove heat from the substrate, as described above, or heat from an area near the embedded microstructure 700. May be manufactured according to a design adapted to best remove.

  Alternative embodiments can be understood or devised by those skilled in the art, where, for example, the substrate can be coupled to a heat sink, such as a copper block, to improve heat transfer. The copper block may then have a plurality of cooling paths therein that help to remove heat from the block. Alternatively, the substrate can be attached to a thermoelectric cooler, and a voltage is applied to a specially created semiconductor device therein. In these devices, the current flow causes cooling on one side and heating on the other. Commercial devices such as Peltier coolers can generate temperature differences of up to 70 ° C. throughout the device, but the overall ability to remove large amounts of heat from a heat source can be limited.

  Alternatively, the substrate is attached to a cryocooler, such as a block with a path through which liquid nitrogen flows, or in thermal contact with a liquid nitrogen container or another cryogenic substrate for stronger cooling. Can be supplied. When the substrate comprises a material such as diamond, sapphire, silicon, or silicon carbide, the thermal conductivity generally increases with decreasing temperature from room temperature. In such cases, it may be preferable to design the target to withstand these cooler temperatures.

  Appendix diagram 15 illustrates another embodiment in which a plurality of cavities formed in the substrate 1000 are (preferably of a minimum thickness) prior to embedding the X-ray generating material that forms the plurality of microstructures 700. It is first coated with an adhesion layer 715. Such an adhesion layer may be appropriate when the bond between the X-ray material and the substrate material is weak. The adhesion layer can also serve as a buffer layer when the difference in thermal expansion coefficient between the two materials is large. In some material choices, the adhesion layer can be replaced with a diffusion barrier layer to prevent the material from diffusing from multiple microstructures into the substrate material (or vice versa), or (another layer can be Can be enlarged). In embodiments where an adhesion layer and / or a diffusion barrier layer are used, the materials and materials are such that the heat flow from the plurality of microstructures 700 to the substrate 1000 is not significantly hindered or insulated by the presence of the adhesion layer 715. The choice of thickness should also take into account the thermal properties of the layer.

  Appendix diagram 16 shows another embodiment in which a conductive layer 725 is added to the surface of the target. When bombarded with electrons, the extra charge requires a path to return to the ground of the target that effectively functions as the anode. A target such as that illustrated in appendix 13 has a plurality of discrete, unconnected microstructures 700 in an electrically isolated substrate material (such as undoped diamond) and continued electrons. When under impact, large charges can accumulate on the surface. In addition, electrons from the cathode may not collide or even repel targets with the same energy, reducing x-ray generation.

  This is to deposit a thin layer of conductive material, preferably a relatively low atomic number such as aluminum (Al), beryllium (Be), carbon (C), chromium (Cr), or titanium (Ti). This may allow electrical conduction from a plurality of discrete microstructures 700 to an electrical path 722 connected to the positive electrode for a high voltage source. In practice, this terminal is typically the electrical ground of the system and a negative high voltage is supplied to the cathode electron source.

  Appendix diagram 17 illustrates another embodiment of the present invention in which a plurality of microstructures 702 are embedded or embedded in substrate 1000. Such buried microstructure can be further covered by the deposition of an additional layer 1010, which can be, for example, diamond, and can provide the same thermal conductivity characteristics as the substrate. This allows heat to be dissipated from all surfaces of the buried microstructure 702. However, in such a situation, it is desirable to provide a path 722 to ground for electrons incident on the structure, which is in the form of a buried conductive layer 726 provided prior to depositing the additional layer 1010. It may be. In some embodiments, this conductive layer 726 is a “via” 727 that provides a conductive structure for coupling the buried conductive layer 726 to an additional conductive layer 728 on the target surface, or a vertical connection. , Often in the form of pillars or cylinders, then the additional conductive layer 728 is connected to a path 722 to ground.

  Appendix diagram 18 illustrates another embodiment of the present invention in which the microstructures have a plurality of additional structures in sequence. Instead of a uniform microstructure, a microstructure having a bottom layer 731, an intermediate layer 732, and a top layer 733 is shown. These layers can be selected to have different X-ray generating materials such that the whole emits multiple characteristic lines. Alternatively, instead of having a plurality of separate layers, a microstructure with a plurality of adjacently arranged materials may be used to achieve the desired X-ray emission spectrum. Alternatively, instead of having separate layers, a microstructure with a uniform or diverse mixture or alloy of two or more materials is used to achieve the desired X-ray emission spectrum. Also good. Another embodiment has an intermediate layer 732 having the same material as that of the substrate, providing high heat dissipation for the top layer 733 and the bottom layer. In addition, a conductive layer may be added along the sidewall (not shown) to provide an electrical path to the conductive path, as shown in Appendix Figure 16 and Appendix Figure 17.

  Appendix diagram 19 illustrates another embodiment of the present invention, again with a plurality of microstructures 702 embedded in the substrate. However, in this embodiment, instead of first providing a conductive layer and then depositing an additional cap layer, only a single layer 770 selected for the combination of electrical and thermal properties, Deposited in this embodiment. This may be, for example, the deposition of carbon nanotubes (atomic number 6) arranged perpendicular to the surface to carry both heat and electrons from the plurality of embedded microstructures 702. This single layer 770 may then be connected to a path 722 to ground to allow the target to act as the anode of the x-ray generation system. Alternatively, the material of layer 770 can be selected to have aluminum (Al), beryllium (Be), chromium (Cr), or copper (Cu).

  Several embodiments are shown separately in Appendix Figure 13 through 19 in Appendix Figure, and various processes for manufacturing them will be shown later, but the elements of these embodiments may be combined with each other, or It will be apparent to those skilled in the art that it can be combined with other commonly known multiple target manufacturing methods known in the art. For example, the plurality of embedded microstructures 702 in the appendix diagram 19 may also have a plurality of materials as illustrated in the appendix diagram 18. Similarly, an adhesion layer 715 as illustrated in Appendix diagram 15 may be applied to manufacture a plurality of buried microstructures 700 as illustrated in Appendix diagram 16. The separation of these alternatives is for illustrative purposes only and is not intended to limit any particular process.

  Although the plurality of microstructures illustrated in the appendix diagram 13 to the appendix diagram 19 are shown as regularly spaced patterns having uniform size and shape, the uniform microstructure irregular pattern or random pattern Alternatively, a regular pattern of microstructures having various sizes and shapes, or an irregular pattern of microstructures having various sizes and shapes can also be used in embodiments of the present invention.

  Similarly, although some embodiments have been described with microstructures in the shape of, for example, rectangular prisms, multiple manufacturing processes can be performed at angles other than 90 ° depending on the particular process product used. Or may have multiple structures that can be rounded, chamfered, or undercut, rather than having right-angled corners. Embodiments in which the microstructures are substantially similar to the shapes described herein may be used even if the process products result in some deviation from the shapes as illustrated or described. Will be understood by those skilled in the art as disclosed.

  Similarly, the various embodiments disclosed herein may be illustrated with a regular periodic array of multiple microstructures, but the relative positions, sizes, and shapes of discrete microstructures are regular, periodic Or need not be uniform. Multiple microstructure configurations having various sizes and spacings that may have various distances between the multiple microstructures may also work.

3. Various Microstructure Shapes Specific embodiments of the present invention have been described in the previous section. However, besides multiple variations in multiple layers and structures, multiple embodiments also have multiple microstructures of various sizes and shapes.

  Appendix diagram 20 shows a region 1011 of a target having two regular arrangements of microstructures 700 and 702 in the form of rectangular prisms, typically containing a metallic X-ray generating material, according to one embodiment of the present invention. Is shown. The arrays are staggered at different depths in the lateral direction so that when under electron irradiation, each microstructure is surrounded by a “cooler” substrate material. The physical separation of multiple microstructures provides multiple small hot spots in a cooler, broader material, thereby creating many local temperature gradients that rapidly dissipate heat from the multiple microstructures. 20A of the appendix diagram shows a perspective view of 16 embedded microstructures 700 and 9 embedded microstructures 702 in this embodiment, 20B of the appendix diagram shows a top view of the same region, and 20C of the appendix diagram is the same A side / sectional view of the region is shown.

  As illustrated in appendix 21A, embedded microstructure 702-A can be made slightly larger than embedded microstructure 700 such that electrical contact is established between structures in different layers. . If the embedded microstructure 702-A has sufficient electrical conductivity, then a single electrically conductive layer 725 that provides a path 722 to ground may be sufficient to prevent charging of both layers. .

  On the other hand, the configuration illustrated in 21A of the appendix may provide only a region that is too small to provide effective thermal and electrical conduction, depending on the settings of electronic energy and material composition.

  In order to cope with this, as illustrated in FIG. 21B of the appendix, the plurality of embedded microstructures 702-B are embedded deeper in the substrate 1000, and the plurality of embedded microstructures 702-B are connected to the path 722 to the ground. It can be fabricated with its own conductive layer 726 connected by vias 727 that provide additional electrical connections. This configuration may be preferred for some applications because it provides a long distance between multiple sources of heat and x-rays.

  In some manufacturing processes, the etching process can be adjusted to provide an undercut. [For example, for both isotropic and anisotropic etching of diamond, see, for example, D.C. S. Hwang, T .; Saito, N .; Fujimori, “New etching process for device manufacturing diamond,” Diamond & Related Materials, Vol. 13, pp. 2207-2210 (2004)]. The undercut process is selected to etch multiple cavities used to form multiple microstructures into the substrate, and multiple using isotropic processes such as electroplating that can fill all cavities. When a plurality of microstructures are formed, a plurality of microstructures “fixed” in a predetermined position can be formed as illustrated in FIG.

  Appendix diagram 22 illustrates a region 1012 of a target according to one embodiment of the present invention having an array of microstructures 704 formed by filling a plurality of cavities with undercuts in a substrate 1000. Yes. The multiple microstructures 704 so formed are in the form of trapezoidal columns with X-ray generating material. The array as shown is arranged as an embedded array on the surface of the substrate, and the “lip” or remaining substrate material around the surface better holds the plurality of microstructures 704 in place, It works to prevent delamination when subjected to stress or thermal overload. 22A of the appendix diagram shows a perspective view of 16 trapezoidal embedded microstructures 704 in this embodiment, 22B of the appendix diagram shows a top view of the same region, and 22C of the appendix diagram shows a side surface / A cross-sectional view is shown.

  Appendix diagram 23 illustrates a region 1013 of a target having a checkered array of microstructures 700 and 701 in the shape of a rectangular prism containing X-ray generating material, according to one embodiment of the present invention. The array as shown is arranged as a buried array on the surface of the substrate. 23A of the appendix diagram shows a perspective view of the 25 buried microstructures 700 and 701 in this embodiment, 23B of the appendix diagram shows a top view of the same region, and 23C of the appendix diagram is shown by a dotted line FIG. 5 shows a side / cross-sectional view of the same region with multiple recessed regions.

  Appendix diagram 24 shows a region 1014 of a target according to one embodiment of the invention having an array of a plurality of microstructures 706 in the form of a right circular cylinder containing an X-ray generating material. The array as shown is arranged as an array embedded in the substrate. 24A of the appendix diagram shows a perspective view of the 16 embedded microstructures 706 in this embodiment, 24B of the appendix diagram shows a top view of the same region, and 24C of the appendix diagram shows the center of the column of the microstructures 706 A side / section view of the same region throughout is shown.

  Appendix diagram 25 also shows a region 1015 of the target according to one embodiment of the present invention having a dense array of microstructures 708 and 709 in the form of a right cylinder containing X-ray generating material. The dense array as shown is also arranged as a buried array on the surface of the substrate. However, in this embodiment, when viewed from the side or from the end, the X-ray source appears to have no “gap” present in the configuration of FIG. 25A of the appendix diagram shows a perspective view of the 18 embedded microstructures 708 and 709 in this embodiment, 25B of the appendix diagram shows a top view of the same region, and 25C of the appendix diagram shows the depth feeling of the same region. A side / sectional view is shown.

  Appendix diagram 26 illustrates a region 1016 of a target according to one embodiment of the present invention having a dense array of microstructures 711 and 712 in the form of a regular triangular prism containing x-ray generating material. The dense array as shown is arranged as a buried array on the surface of the substrate. 26A in the appendix diagram shows a perspective view of the 18 embedded microstructures 711 and 712 in this embodiment, 26B in the appendix diagram shows a top view of the same region, and 26C in the appendix diagram shows the depth feeling of the same region. A side / sectional view is shown.

  Appendix diagram 27 shows a region 1017 of a target according to one embodiment of the present invention having a dense array of microstructures 713 and 714 in the form of a tetrahedron containing x-ray generating material, one side being a substrate. It is almost flush with the surface of 1000. The dense array as shown is arranged as a buried array on the surface of the substrate. 27A in the appendix diagram shows a perspective view of the 18 embedded microstructures 713 and 714 in this embodiment, 27B in the appendix diagram shows a top view of the same region, and 27C in the appendix diagram shows the depth feeling of the same region. A side / sectional view is shown.

  Appendix diagram 28 illustrates a region 1018 of a target according to one embodiment of the present invention having a combination of microstructures 700, 701, and 702 described above in the form of a rectangular prism containing x-ray generating material. Yes. In this embodiment, the layers of microstructures 700 and 701 embedded near the surface form a checkered pattern as illustrated in Figure 23 of the appendix, while this structure is an upper checkered “gap”. It also has a buried layer of a plurality of microstructures 702 disposed below. The same is true for the previously described case, but the microstructures of the buried layer may be large enough to make electrical contact with the upper buried layer microstructures 700 and 701, but the other In this embodiment, a separate conductive layer that releases charge from the buried microstructure 702 can be fabricated to provide a path to ground. Appendix A 28A shows a perspective view of 48 embedded microstructures 700, 701 and 702 in this embodiment, Appendix B 28B shows a top view of the same region, and Appendix C 28C shows the same region. A side / sectional view with a sense of depth is shown.

  Appendix diagram 29 shows a region 1019 of a target according to one embodiment of the present invention having both embedded microstructure 716 and embedded microstructure 717 in the form of a long rectangular column containing x-ray generating material. In the embodiment as shown, in alternating layers, long prisms are arranged to extend in directions orthogonal to each other, often in a configuration referred to as a “stack-of-logs” configuration. ing. The same is true for the previously described case, although the buried layer microstructures 717 may be in electrical contact with the upper buried layer microstructure 716, but in other embodiments, the buried microstructures A separate conductive layer that releases charge from 717 can be fabricated to provide a path to ground. 29A in the appendix diagram shows a perspective view of the microstructures 716 and 717 in this embodiment, 29B in the appendix diagram shows a top view of the same region, and 29C in the appendix diagram has a side / section with a sense of depth in the same region. The figure is shown.

  Appendix diagram 30 shows a region 1020 of a target according to one embodiment of the present invention having an array of microstructures 718 in the form of a sphere containing x-ray generating material. The array as shown is arranged as a buried array on the surface of the substrate. 30A of the appendix diagram shows a perspective view of 16 embedded microstructures 704 in this embodiment, 30B of the appendix diagram shows a top view of the same region, and 30C of the appendix diagram shows a side / sectional view of the same region. Show.

  Fabrication of the area of the embedded sphere as illustrated in appendix 30 may in some embodiments have a good mechanical rigidity or lower manufacturing cost, but a spherical cavity in which material can be deposited. Forming on a substrate can present multiple process challenges. Thus, in some embodiments, a hemispherical cavity can be formed in the substrate, which is then filled with x-ray generating material, or a pre-fabricated sphere is deposited on the surface, resulting in over-deposition. It can be covered with a coating film material.

  As previously discussed, the various embodiments disclosed herein may be illustrated with a regular periodic or regular arrangement of multiple microstructures, but the relative location, size, And the shape need not be regular, periodic, or uniform. Multiple microstructure configurations having various sizes and spacings that may have various distances between the multiple microstructures may also work.

  In some embodiments, various metrics can be used to determine the size and distribution of multiple microstructures with x-ray generating materials. The multiple microstructures are specified to have a predetermined thickness D in the target, and as discussed previously, D is the electron penetration of electrons of a given energy in a given x-ray generating material. It can be selected to be a certain percentage of depth (eg, 30% or 50%, etc.) or it can be a range of allowed depths. The multiple microstructures are such that their lateral dimensions L and W do not exceed D (eg, 2 or 3 times) multiplied by a specific factor or more, and any individual microstructure is an adjacent microstructure. It can be specified that the structure is no closer than a predetermined distance d. Alternatively, multiple microstructures do not allow these lateral dimensions L and W to exceed different X-ray attenuation lengths (lengths where the intensity of an X-ray beam of a particular energy is reduced to 1 / e times) depending on the application. Can be specified.

  In the most general case, a region having a plurality of microstructures can be identified by defining the volume fraction of the entire region exposed to electrons up to a thickness D having an X-ray generating material. For example, if multiple microstructures of tungsten (W) are used with 60 keV electrons, the penetration depth according to Table 2 is 2.41 microns, and the value D = 1 microns is equivalent to 41% of the penetration depth. Will represent. As long as the volume fraction of the X-ray generating material relative to the substrate material is approximately 50% within the target region that includes multiple microstructures but does not include the surrounding target substrate, for the initial layer thickness D = 1 micron Defining a volume fraction of 50% is achieved either by using, for example, the checkered arrangement of 23 in the appendix or by a more randomly distributed microstructure of various sizes and shapes obtain. Such multiple configurations may provide advantages with respect to additional surface area for heat conduction, for example.

  In addition, the volume fraction of the X-ray generation region can be set to various values according to the electron energy, the X-ray generation material characteristics, and the substrate reabsorption characteristics. For some applications that require a specific plurality of characteristic lines, a configuration with a lower volume fraction may be preferred. In other variations on the emission spectrum, such as those with different wavelengths, higher volume fractions that increase bremsstrahlung may be preferred. In general, the volume fraction in the first layer of thickness D can be set to be between 15% and 85% for various applications.

  Alternatively, in some embodiments, a plurality of spherical microstructures of x-ray generating material can be pre-prepared and then dispersed over the surface of the substrate. In particular, when it is desired that a plurality of microstructures be arranged in a regular array (as illustrated in appendix 30), a process of fixing the plurality of microstructures in place is used. obtain. This is followed by a deposition process in which these spherical microstructures are covered with a thermally conductive material. In some embodiments, this may be a material selected only for its thermal conductivity properties, but in other cases, the deposited material will benefit from both thermal and electrical conductivity. Can be selected as a mixture of a plurality of materials selected to be, and the overlying material also acts as a conductive layer that provides a path to ground.

  In another embodiment, the distribution of the microstructures with the X-ray generating material need not be limited to a uniform sphere, but may be a plurality of particles of various sizes and shapes. This is illustrated in Appendix diagram 31. A target region 1021 according to the present invention has a plurality of various microstructures. Similarly, in a similar embodiment, as illustrated in Appendix Figure 32, the region 1022 of the target according to the present invention has not only microstructures of various sizes and shapes but also microstructures of different material compositions. obtain.

  Up to this point, a plurality of embodiments arranged in a planar structure have been shown. These are generally easier to implement. Because equipment and process recipes for multiple steps of deposition, etching, and other planar processes include processing of devices for microelectromechanical system (MEMS) applications using planar diamond, and silicon wafers for the semiconductor industry. This is because it is well known in processing.

  However, in some embodiments, a surface with additional properties in three dimensions (3-D) may be desired. As previously discussed, when the electron beam is larger than the electron penetration depth, the apparent x-ray source size and region is parallel to the surface, ie when viewed at an extraction angle of zero degrees (0 °). Minimized (and brightness maximized). As a result, X-ray emission with apparent maximum brightness occurs when viewed at a 0 ° extraction angle. Emissions from within the x-ray generating material accumulate as it propagates through the material at 0 °.

  However, in a broad target of substantially uniform material, as the x-rays propagate through the material to the surface, the attenuation of the x-rays between multiple sources of x-rays within the target reduces the extraction angle. And increases due to the longer distance traveled within the material, often maximizing at or near an extraction angle of 0 °. Thus, any increase in brightness achieved by viewing near 0 ° can be balanced by reabsorption. The distance at which the X-ray beam decreases in intensity to 1 / e is called the X-ray attenuation length. Therefore, a configuration having a distance selected in relation to the x-ray attenuation length that does not allow the emitted x-rays to pass through as much further material as possible may be desired.

  An illustration of one embodiment of the target is shown in Appendix diagram 33. In the appendix diagram 33, the X-ray generation region having a single microstructure 2700 is configured at or near the recessed edge 2003 of the substrate in contact with the shelf 2002 and is illustrated in appendix diagram 10. Similar to the situation. The X-ray generation fine structure 2700 has a rectangular bar shape made of an X-ray generation material, is embedded in the substrate 2000, and emits X-rays 2888 when bombarded with electrons 111.

  The bar thickness D (thickness along the surface normal of the target) is between 1/3 and 2/3 of the electron penetration depth of the X-ray generating material at the incident electron energy for optimum thermal performance. Selected. The thickness D of the bar can also be selected to obtain a desired X-ray source size in the vertical direction. The width W of the bar is selected to obtain the desired source size in the corresponding direction. As illustrated, W is approximately 1.5 times D, but can be substantially smaller or larger depending on the size of the desired source spot.

  As illustrated, the bar length L is approximately 4 times D, but can be of any size and is typically 1 / X of the x-ray attenuation length of the selected x-ray generating material. It can be determined to be between 4 and 3 times. As illustrated, the distance p between the edge of the shelf and the edge of the X-ray generating material is approximately equal to W, but the X-ray reabsorption characteristics, relative thermal characteristics, and electrons of the substrate material Depending on the amount of heat expected to be generated when an impact is applied, an arbitrary value may be selected from a point that is coplanar with the edge 2003 (p = 0) to a maximum of 1 mm.

  An illustration of another embodiment of the present invention is shown in appendix diagram 34. In this embodiment as illustrated, a target according to the invention having an X-ray generating region with six microstructures 2701, 2702, 2703, 2704, 2705, 2706 is recessed in the substrate in contact with the shelf 2002 It is configured at or near the edge 2003 and is similar to the situation illustrated in Appendix diagram 10 and Appendix diagram 33. X-ray generation microstructures 2701, 2702, 2703, 2704, 2705, 2706 are arranged in a linear array of rectangular prisms that generate X-rays embedded in the substrate 2000, and when X-ray generation is impacted by electrons 111 Line 2888-D is emitted.

  In this embodiment, the total volume of the X-ray generating material is the same as in the illustration of 33 in the previous appendix. The same applies to the case shown in Appendix 33, but the bar thickness D (thickness along the surface normal of the target) is the electron of the X-ray generating material at the incident electron energy for optimum thermal performance. It is selected to be between 1/3 and 2/3 of the penetration depth. The same is true in the case shown in Appendix 33, but the bar width W is selected to obtain the desired source size in the corresponding direction, and as illustrated, W is approximately 1.5 of D. Is double. As discussed previously, the bar width W can be substantially smaller or larger depending on the size of the desired source spot.

  However, a single bar 2700 of length L as illustrated in appendix 33 is replaced with six subbars 2701, 2702, 2703, 2704, 2705, 2706, each length l being L / 6. The volume of X-ray generation (when bombarded with the same electron density) is the same, but here each subbar has five faces that transfer heat to the substrate, and from X-ray generation subbars 2701-2706 Increase heat dissipation to the substrate. As illustrated, the separation distance d between the sub-bars is approximately equal to l, but larger or smaller dimensions may be used, which are the X-ray dose absorbed by the substrate and the X-rays Depends on the relative temperature gradient that can be realized between the particular material of the generated microstructure 2701-2706 and the substrate 2000.

  Similarly, the distance p between the edge of the shelf and the edge of the X-ray generating material is approximately equal to W as illustrated, but the X-ray reabsorption characteristics, relative thermal characteristics of the substrate material. Depending on the amount of heat expected to be generated when impacted by electrons, it may be chosen to be any value from where it is coplanar with edge 2003 (p = 0) to a maximum of 1 mm. .

  In the configuration shown in the appendix diagram 34 and the like, the total length of the plurality of X-ray generation subbars is generally about twice the X-ray linear attenuation length in the X-ray generation material. You can select up to more. Similarly, the bar thickness D (thickness along the surface normal of the target) is equal to 1/3 to 2/3 of the electron penetration depth of the X-ray generating material at the incident electron energy for optimum thermal performance. Although selected to be, it can be substantially larger. The thickness D of the bar can also be selected to obtain a desired x-ray source size that is approximately equal in the relevant direction.

  The bars shown may be embedded in the substrate (as shown), but may be placed on the substrate if the thermal load generated on the x-ray generating material is not too great.

  An illustration of another embodiment of the present invention is shown in Appendix Figure 35, where a region of a target according to one embodiment of the present invention having an array of microstructures 2790 and 2791 comprising an X-ray generating material having a thickness D 2001 is shown. The arrangement shown is a modified checkered pattern of rectangular prisms, but other configurations and arrangements of multiple microstructures may be used.

  Similar to other embodiments, these microstructures 2790 and 2791 are embedded in the surface of the substrate. However, the surface of the substrate has a predetermined non-planar topography, in this particular case, a plurality of steps along the surface normal of the substrate 2000. As illustrated, the height h of each step is approximately equal to D, but the step height can be selected to be between 1 and 3 times the thickness of the plurality of microstructures. The total height of all steps can be selected to be equal to or smaller than the desired x-ray source size along the vertical direction (thickness direction).

  The total width of the microstructure region can be equal to the desired x-ray source size in the corresponding direction. The overall appearance resembles an X-ray source staircase. 35A in the appendix shows a perspective view of 18 buried microstructures 2790 and 2791 in this embodiment, 35B in the appendix shows a top view of the same region, and 35C in the appendix shows a side / section of the same region. The figure is shown. When the substrate is beryllium, diamond, sapphire, silicon, or silicon carbide, an electrically conductive layer can be coated on the top surface of the step structure.

  Appendix diagram 36 shows X-ray emission 2888-S from the stepped embodiment of 35C of the appendix diagram when impacted by electrons 111. As in other embodiments, the plurality of prisms of the X-ray generating material are heated when the electrons collide. Since each of the plurality of prisms of the X-ray generating material has five surfaces that are in thermal contact with the substrate 2000, the conduction of heat from the X-ray material is caused by the X-ray material on the surface. Still larger than the deposited composition. However, for one surface, x-ray emission is not attenuated by absorption by other adjacent prisms, but is negligibly attenuated by adjacent substrate material.

  Thus, the brightness of the X-rays from the respective prisms also shows a plurality of prisms 700 and 701 of X-ray generating material arranged in a checkered pattern, for example X-ray emission from the embodiment of FIG. Increases when compared. In the configuration of Appendix 23, each prism is embedded in the substrate and thus has five surfaces in thermal contact with the substrate 1000, but the lateral emission at 0 ° is adjacent. Is attenuated by both the plurality of prisms and the substrate material.

  One such embodiment comprising a target with topography first prepares the substrate with topography and then embeds multiple prisms of X-ray material according to the planar substrate manufacturing process described previously. Can be manufactured. Alternatively, the initial steps of forming cavities filled with x-ray material can be enhanced to form a stepped topographic structure on the initial flat substrate. In either case, additional registration steps, such as known to those skilled in the planar process, are used when it is desired to overlay the embedded prism with a particular feature topography. obtain.

  Multiple microstructures may be embedded at a distance from the edge of the staircase as illustrated in appendix diagram 35 and appendix diagram 36, or (as shown in appendix diagram 9) It can be embedded to be flush with the edge. The determination of which configuration is appropriate for a particular application can depend on the exact properties of the x-ray generating material and the substrate material, such as transfer of heat by, for example, five or four surfaces. The additional brightness realized by the increase in electron current made possible by the can be compared with the additional brightness realized by free space emission or reabsorption through a part of the substrate material. The additional costs associated with the alignment and overlay steps, as well as the multiple process steps that may be required to pattern multiple prisms in multiple layers, are considered relative to the increase in brightness that can be achieved. It may be necessary.

  The embodiments described so far are various X-ray targets comprising a plurality of microstructures having an X-ray material that can be used as a target of an X-ray source to generate X-rays with increased brightness. Explains the configuration. Although these target configurations have been described as being bombarded with electrons and emitting X-rays, they can be used as fixed X-ray targets in other conventional sources to produce a transmission X-ray source 08 in Figure 1 of the Appendix. Either the target 01 or the target 100 of the reflective X-ray source 80 of Figure 2 in the Appendix can be replaced with a target according to the present invention.

  Embodiments as described can equally well be applied to a mobile x-ray target, for example, the target 500 of the rotating anode x-ray source 80 of appendix 6 can be replaced with a target according to the present invention. It is also possible.

  Appendix diagram 37 illustrates one embodiment of the present invention configured as a rotating anode 2500. A plurality of x-ray generating materials are formed on the outer annular portion of the rotating anode 2500 and can be formed by any of the processes previously described. In the embodiment as illustrated in appendix 37, two separate materials are illustrated, each with various shapes in the form of either annular rings 2508 and 2509 or square structures 2518 and 2519. Has a fine structure.

  As in a conventional rotating anode, the electrons impact the edge target anode 2500, which can be chamfered just as a conventional rotating anode is chamfered, and the source of the electron beam is the target anode. An electron beam is directed onto 2500 chamfered edges 2510 to generate x-rays from target spot 2501. Since the target spot 2501 generates X-rays and is heated, the target anode 2500 is rotated, so that the heating spot is separated from the target spot 2501 and the electron beam irradiates a lower temperature portion of the target anode 2500 here. Prior to being heated again when passing hot spot 2501, the hot spot has a time for one revolution to cool. By continuously rotating the target anode 2500, a single spot does not get too hot, but can still provide a continuous source of x-rays.

  Similar to the previously described rotating anode system, but in order to further cool the anode, the rotating anode is provided with a plurality of additional cooling paths to bombard electrons with higher voltage or higher current density. It is possible to form a brighter x-ray source. However, when the rotating anode target material uses a plurality of microstructures according to the invention disclosed herein, the improved thermal properties may allow higher electronic power loads. This allows for a brighter X-ray source once the energy and current can be increased once it can be accommodated for further heat loads. Alternatively, thermal benefits to allow a rotating anode source with multiple components that are easier to design, such as the same brightness but lower voltage, lower current, or slower anode rotation speed Can be used.

4). Manufacturing Process A plurality of methods for manufacturing a target according to the present invention includes a plurality of steps outlined in the flow chart of appendix figure 38 and the cross-sectional view of appendix figure 39 to appendix figure 40. .

4.1. Substrate Selection In the first step, a substrate 3000 of suitable material is selected. In the appendix diagram 39A, this is indicated by the process designated "1)". As discussed above, this is typically a material selected for various physical and thermal properties, particularly low mass density, low atomic number, and high thermal conductivity. Several candidates for substrate materials are listed in Table 1, some having high thermal conductivity (ie, materials with thermal conductivity greater than 100 W / (m ° C.)). Among these materials, diamond stands out as a potential substrate. At room temperature, the thermal conductivity is approximately 2200 W / (m ° C.), one of the highest values already known for any material. At lower temperatures, approximately -120 ° C, this value can increase to almost three times higher.

  Wafers coated with diamond up to 2 mm thick on diamond grown to 120 mm diameter can be purchased from Diamond Materials GmbH, Freiburg, Germany. Diamond-coated silicon substrates, or diamond-on-insulator (DOI) substrates, are also available, for example, from Advanced Diamond Technologies, Inc., Rom Orville, Ill. Or from sp3 Diamond Technologies of Santa Clara, California. Richter Precision, Inc., East Petersburg, Pennsylvania. Diamond-like carbon (DLC) films, such as manufactured by may also be useful as substrate materials.

  Beryllium can also be a candidate substrate material. Because of its low atomic number (atomic number 4), beryllium is very light and is particularly transmissive to X-rays, and thus can prevent X-ray emission from multiple microstructures embedded in the substrate. Difficult to be a source of lines. Beryllium wafers are available, for example, from American Elements, Inc. of Los Angeles, California. And commercially available from Atomic Chemicals Corporation of Farmingdale, NY.

  Other materials that may be suitable as a substrate are graphite, silicon, boron nitride, gallium nitride, silicon carbide, and sapphire. Other suitable materials may be known to those skilled in the art.

4.2. Substrate Patterning Once a substrate has been selected, the next step 3100 is to pattern the substrate 3001 as shown in appendix 39A, as shown in appendix 38. There are multiple known approaches for patterning diamond for MEMS applications, nanoimprint lithography, and other processes. [E.g. Masuda et al., “Fabrication of Through-Hole Diamond Membranes by Plasma Etching Using Alumina Mask, Vol. 101, Electro-Sol. Ando et al., “Smooth and high-reactive reactive etching of diamond”, Diamond and Related Materials, 11 (2002), 824-827 (2002), X. D. Wang et al., “Precision patterning of diamond films for MEMS application”, J. Am. Material Processing Technology Vol. 127, pages 230-233 (2002), J. MoI. Taniguchi et al., “Diamond Nanoimprint Lithography”, Nanotechnology Volume 13, pages 592-596 (2002); S. Hwang / T. Saito / N. Fujimori, “New etching process for device manufacturing diamond,” Diamond & Related Materials, Vol. 13, pp. 2207-2210 (2004)].

  In the process cited above by Masuda et al., A polished polycrystalline diamond film approximately 3 mm thick is patterned using a porous alumina mask. The mask is pre-prepared with a silicon carbide mold that forms a pattern on the aluminum surface, which is subsequently oxidized by an anodization process. The alumina film thus formed has a plurality of pores whose positions are determined by the pattern on the SiC mold. The film is then removed from the aluminum substrate and transferred to the diamond surface. The diamond is then subjected to a reactive ion etching process with oxygen, where the porous alumina film serves as a mask.

  A plurality of representative steps for this process step 3100 are the correspondence of 39A in the appendix diagram indicated by “a)”, “b)”, “2)”, “3)”, and “4)”. It is illustrated by the process of doing.

  In the process “a)” of 39A in the appendix, the mask 3060 is formed on the substrate 3050 and patterned. The mask can be, for example, alumina patterned on an aluminum substrate. In step “b)”, the mask is removed. In step “2)”, the mask 3060 is attached to the substrate 3000. In step “3)”, the mask and the substrate are subjected to a pattern transfer step such as reactive ion etching (RIE) using oxygen to form a patterned substrate 3001 from the first substrate 3000. In step “4)”, the mask 3060 is removed, and the patterned substrate 3001 remains.

  Alternatively, the substrate can be patterned using conventional multiple lithographic processes. These may include coating the substrate with a photoresist such as HSQ and exposing the resist to a pattern representing the desired structure formed on the wafer using an electron beam or ultraviolet photons. The resist is then developed to remove the exposed areas and expose the substrate. Next, the combination of the substrate and the patterned resist is processed by an appropriate etching process (such as reactive ion etching (RIE) using oxygen gas) that transfers the resist pattern to the substrate. Once this is complete, the excess resist is removed, resulting in a patterned substrate that is substantially the same as the patterned substrate 3001 shown in step “4)” of Appendix A 39A and Appendix B 39B. Remain.

  In a variation on the lithographic patterning process described above, the substrate can be coated with a specially selected material that serves as a hard mask for patterning the substrate. In this case, a plurality of steps include coating a hard mask on the substrate, coating the resist on the hard mask, patterning the resist by either electron beam exposure or light exposure, developing the resist, and converting the resist to the hard mask. Pattern transfer, pattern transfer from the hard mask to the substrate, patterned substrate 3001 substantially the same as the patterned substrate 3001 shown in the step “4)” in the appendix 39A and the appendix 39B. It is to leave the substrate. Such multiple lithography processes and variations thereof may be well known to those skilled in the art.

  In other alternatives to the lithographic patterning processes described above, the substrate can also be directly ion milled using a machine such as a focused ion beam. Several other techniques, such as laser etching, can also be used to pattern the substrate.

4.3. Embedding X-Ray Material Once the substrate has been patterned, the next step is depositing 3300 a material that can generate X-rays of the desired characteristics in the patterned cavities. This depends on the material, any number of well-known depositions, including chemical vapor deposition (CVD), sputtering, electroplating, mechanical stamping, or other techniques that would be known to those skilled in the art. Get technology. Aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, Various materials can be selected for use as the x-ray generating material, including cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

  A plurality of representative steps for this process step 3300 are illustrated by the corresponding steps in 39B of the appendix diagram indicated by “5)”.

  Once the x-ray material is deposited, excess material is typically present on the substrate. The next polishing step 3500 using either a mechanical abrasive polishing process or a chemical mechanical polishing (CMP) process removes excess material and corresponds to the corresponding step of 39B in the appendix diagram shown at “6)”. As illustrated by FIG. 2, leaving a plurality of cavities in the patterned substrate 3001 that are now filled with discrete microstructures 3401 of x-ray material.

4.4. Alternative Adhesive Materials Some materials, when used in combination with a particular substrate, can form an interface layer that provides a good bond between them. For example, for selected x-ray materials such as tungsten, CVD deposition 3400 of tungsten material on a patterned diamond substrate 3001 causes the diamond cavities to be strongly carbonized at the boundary between tungsten and carbon. May be suitable for filling with tungsten to form. However, in other materials such as copper, the use of an adhesion layer, such as depositing a 10 nm thick layer of titanium (Ti) or chromium (Cr) between the copper and diamond substrate, Improve the mechanical integrity of the anode both by improving the adhesion between them and also in some cases by preventing the material from diffusing from one region to the other. May be preferable.

  A plurality of representative steps for this process step are illustrated by the 40 corresponding steps in the appendix diagrams indicated by ““ 5) ”,“ 5a) ”,“ 6a) ”, and“ 7a) ”. ing.

  In the appendix diagram 40 starting with the patterned substrate 3001, step “5a)” illustrates the deposition of a suitable adhesion layer 3350 on the patterned substrate 3001. A typical adhesion layer 3350 can be, for example, a layer of chromium (Cr) or titanium (Ti) when used with copper (Cu) as the X-ray material. The other materials may include a carbide alloy of the target material, such as copper carbide (CuC) for copper or aluminum carbide (AlC) for aluminum. In addition, other materials known to those skilled in the art that have good adhesion to both materials may be used. As an example, molybdenum is often used as a barrier layer for copper. Furthermore, a plurality of material layers such as a titanium carbide (TiC) bilayer or a chromium carbide (CrC) bilayer may be used as the adhesion layer. The thickness of the adhesion layer may vary depending on the selection of the X-ray material and the substrate material, but is typically on the order of 10 nm thickness. Once deposited, the deposition step can be followed by a carbonization step to form a carbonized compound with the substrate. In other embodiments, the carbonized material can be deposited directly to provide an adhesion layer.

4.5. Overcoat film Once the substrate is patterned and multiple cavities are filled to form multiple microstructures of the X-ray material, the next step is to have electrons impacting the X-ray material have a path to ground. A conductive layer to be deposited.

  A representative illustration for this process step 3700 is shown by the corresponding result in 39B of the appendix diagram indicated by “7)”.

  The deposited material 3750 can be a plurality of conductive materials such as beryllium (Be), aluminum (Al), chromium (Cr), titanium (Ti), silver (Ag), gold (Au), copper (Cu), or Or any one of carbon materials such as graphite or carbon nanotubes. The material can be a minimum of 5 nm, or a maximum of 100 nm, but in some situations the material can be a maximum of 500 nm, such as when there is a greater topographic variation in a substrate with multiple cavities filled. .

  The plurality of deposition techniques can be any number of various, including but not limited to chemical vapor deposition (CVD), sputtering, electroplating, mechanical stamping, or other techniques that would be known to those skilled in the art. It can be a deposition technique.

  Once the conductive layer is deposited, a final protective overcoat film or cap layer can also be deposited.

  A representative illustration for this process step 3900 is shown by the corresponding result in 39B of the appendix diagram shown at “8)”.

  The deposition material 3950 can be any one of a plurality of materials, but typically the same material used for the substrate, such as diamond (C), diamond-like carbon (DLC), or beryllium (Be). Or another material such as silicon carbide (SiC), chromium (Cr), molybdenum (Mo), rhodium (Rh), and palladium (PD). The material can be a minimum of 100 nm, or a maximum of 50 microns.

  The plurality of deposition techniques can be any number of various, including but not limited to chemical vapor deposition (CVD), sputtering, electroplating, mechanical stamping, or other techniques that would be known to those skilled in the art. It can be a deposition technique.

  In order to have good adhesion to the underlying layer, the deposition of the cap layer can be performed after deposition of an adhesion layer such as titanium carbide (TiC) that forms the seed layer for diamond growth. The deposit providing this seed layer is very thin, possibly between 1 nm and 5 nm.

4.6. Process Combinations Once these steps have been completed, the final object, indicated by “8)” in 39B of the appendix diagram, is a composite of multiple fines of X-ray generating material suitable for use as a target of an X-ray source. A substrate having a structure is provided.

  Although specific process steps have been described in a specific order, it should be understood that specific processes may be performed in different orders or in combination with each other to achieve similar results. is there.

  For example, although it has been described that deposition of the conductive layer occurs prior to deposition of the cap layer, a combination of these functions, such as that illustrated in Appendix Figure 19 (ie, a conductive cap layer). Similarly, some of the multiple process steps may be repeated to deposit multiple layers of target material as illustrated in appendix 18.

In addition, multiple layer microstructures as illustrated in appendix 21 may be formed by repeating multiple process steps (or portions thereof) as described in this section.
[Appendix Figure 13A]
[Appendix Figure 13B]
[Appendix Figure 13C]
[Appendix Figure 14A]
[Appendix Figure 14B]
[Appendix Fig. 15]
[Appendix Figure 16]
[Appendix Figure 17]
[Appendix Figure 18]
[Appendix Figure 19]
[Appendix Figure 20A]
[Appendix Figure 20B]
[Appendix Figure 20C]
[Appendix Figure 21A]
[Appendix Figure 21B]
[Appendix 22A]
[Appendix 22B]
[Appendix 22C]
[Appendix Figure 23A]
[Appendix Figure 23B]
[Appendix Figure 23C]
[Appendix Figure 24A]
[Appendix Figure 24B]
[Appendix Figure 24C]
[Appendix Figure 25A]
[Appendix Figure 25B]
[Appendix Figure 25C]
[Appendix Figure 26A]
[Appendix Figure 26B]
[Appendix Figure 26C]
[Appendix Figure 27A]
[Appendix Figure 27B]
[Appendix Figure 27C]
[Appendix Figure 28A]
[Appendix Figure 28B]
[Appendix Figure 28C]
[Appendix Figure 29A]
[Appendix Figure 29B]
[Appendix Figure 29C]
[Appendix Figure 30A]
[Appendix Figure 30B]
[Appendix Figure 30C]
[Appendix Figure 31]
[Appendix Figure 32]
[Appendix Figure 33]
[Appendix Figure 34]
[Appendix Figure 35A]
[Appendix Figure 35B]
[Appendix Figure 35C]
[Appendix Figure 36]
[Appendix Figure 37]
[Appendix Figure 38]
[Appendix Figure 39A]
[Appendix Figure 39B]
[Appendix Figure 40]

The first discovery of X-rays by X-rays in 1896 [W. C. Rongen, Eine Neue art von Strahlen (Wiirzburg Verlag, 1895); “On a New Kind of Rays”, Nature, Vol. It was born by chance while experimenting with electron impact on the target. These high energy, short wavelength photons are now used in medical applications and diagnostic evaluation, as well as security inspection, industrial inspection, quality control, and failure analysis, as well as crystallography, tomography, X-ray fluorescence analysis, and the like It is used on a daily basis for scientific applications.

Inside the vacuum tube 02, the emitter 11 connected to the high voltage source 10 through the conducting wire 21 functions as a cathode, and in many cases, a current is passed through the filament to generate a beam of electrons 111. The target 01 is electrically connected to the opposite high voltage lead 22 and thereby acts as an anode. The emitted electrons 111 are accelerated toward the target 01 and collide with the target 01 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of the electrons 111 with the solid target 01 causes multiple effects including the emission of X-rays 888. A portion of the x-ray 888 exits the vacuum tube 02 through a window 04 designed to pass x-rays. In the configuration shown in FIG. 1, the target 01 is deposited or directly mounted on the window 04, which forms part of the wall of the vacuum chamber. In other prior art embodiments, the target may be formed as an integral part of the window 04 itself.

Inside the vacuum tube 20, the emitter 11 connected to the high voltage source 10 through the conductive wire 21 functions as a cathode, and in many cases, a current is passed through the filament to generate a beam of electrons 111. Target 100 which is supported on the target substrate 110 is electrically connected to the opposite side of the high voltage conductor 22 and the target support 32, thereby acting as an anode. The electrons 111 accelerate toward the target 100 and collide with the target 100 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of electrons 111 with the target 100 causes multiple effects including X-ray emission. Some of the X-rays exit the vacuum tube 20 and pass through a window 40 that is transparent to the X-rays.

Returning to FIG. 3, these characteristic X-rays 388 occur primarily at a fraction of the electron penetration depth, shown as the second largest shaded portion 248 of the interaction volume 200. The relative depth is typically affected to some extent by the energy of the electrons 111, which typically decreases with increasing depth. If the electron energy does not exceed the binding energy of the electrons in the target, no characteristic X-rays are emitted. Maximum emission of characteristic lines can occur upon impact with electrons having 3 to 5 times the energy of emitted characteristic X-ray photons. Since these characteristic X-rays are caused by atomic transitions between multiple electron shells, the emission is generally completely isotropic. The actual size of this interaction volume 200 will vary depending on the electron energy and angle of incidence, surface topography and other properties (including local charge density), and the density and atomic composition of the target material. obtain.

Another way to increase the brightness of an x-ray source for bremsstrahlung is to use a higher atomic number Z target material. The reason is that as the atomic number of the material increases, the efficiency of generating X-rays for bremsstrahlung increases correspondingly. Furthermore, the X-ray emitting material should ideally have good thermal properties, such as a high melting point and high thermal conductivity, to allow higher electron power on the source to increase X-ray generation. . For these reasons, targets are often manufactured using tungsten with an atomic number Z of 74. Table 1 shows commonly used X-ray targets, multiple additional potential target materials (especially useful for the particular characteristic line of interest), and some materials that can be used as a substrate for the target material. The materials are described. The melting point and the heat / electric conductivity are values in the vicinity of 300 K (27 ° C.). Most of the values are taken from the 90th edition of CRC "Handbook of Chemistry and Physics" [Boca Raton, Florida, CRC Press, 2009]. Several other values are cited from various sources found on the Internet. It should be noted that for some materials, such as sapphire, thermal conductivity may be an order of magnitude greater when cooled to temperatures below the liquid nitrogen temperature (77 K) [eg, E.C. R. See Dobrovinskaya et al., “Sapphire: Material, Manufacturing, Applications”, Springer Science + Business Media, LLC, Chapter 2.1.5 “Thermal Properties”].

Although it is effective in a particular environment, there is still room for improvement. Liquid metal jets require elaborate water supply and drainage systems and consumables, limiting the materials used (and thus the atomic number values and their associated spectra), making it difficult to increase to higher power. In the case of a uniform solid material thin film target coated on a diamond substrate, there is still a limit to the amount of heat that can be tolerated before damage to the film can occur, even when used in a rotating anode configuration. Heat conduction only occurs through the bottom surface of the membrane. Even in the lateral dimension, there are the same conduction problems that exist in bulk materials.

2 shows a typical X-ray emission spectrum of a tungsten target.

Figure 3 shows X-ray emission from a prior art target when the target is at a 60 ° tilt angle.

Figure 3 shows X-ray emission from a prior art target when the target is at a 45 ° tilt angle.

Figure 3 shows X-ray emission from a prior art target when the target is at a 30 ° tilt angle.

FIG. 19C shows a side / sectional view of the target of FIG. 19C that emits X-rays upon electron impact.

FIG. 29 shows the collection of X-ray emitters of FIGS. 28A and 28B at the next time step t = 2.

FIG . 37 shows a front view of the target and distributed electron beam of FIGS . 37A and 37B .

FIG. 39 shows a front view of the target and distributed electron beam of FIGS . 38A and 38B .

1 illustrates a prior art embodiment of a plurality of x-ray lenses having two cylindrical optical elements .

1 illustrates a prior art embodiment of a plurality of x-ray lenses having a plurality of cylindrical optical elements.

As described above, inside the chamber 20, the emitter 11 connected to the negative electrode of the high voltage source 10 through the conducting wire 21 functions as a cathode, and in many cases, a beam of electrons 111 is generated by passing a current through the filament. Let Any number of prior art techniques for electron beam generation can be used in the embodiments of the invention disclosed herein. Further known techniques used for electron beam generation are heating for thermionic emission, Schottky emission (combination of heating and field emission), multiple emitters with nanostructures such as carbon nanotubes, multiple ferroelectrics Using body material. [For more information on electron emission options for electron beam generation, see Shigehiko Yamamoto, Fundamental Physics of vacuum electron sources (Reports on Progress in Physics, Vol. 69, 181-232A, 6 z). Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophonics (ISRN Nanomaterials, 2014 edition, paper number 879827, page 23 (2014)). Riege, "Electron emission from Ferroelectrics-A Review" (CERN Report CERN AT / 93-18, Switzerland / Geneva, July 1993)].

As described above, the target 1100 having the target substrate 1000 and the region 700 of the X-ray generating material is electrically connected to the opposite high voltage conductor 22 and the target support portion 32, thereby serving as an anode. The electrons 111 are accelerated toward the target 1100 and collide with the target 1100 with high energy having electron energy determined by the magnitude of the acceleration voltage. The collision of electrons 111 with the target 1100 causes multiple effects including the emission of X-rays. Some of the X-rays exit the vacuum tube 20 and pass through a window 40 that is transparent to the X-rays.

However, in some embodiments of the present invention, an electrostatic lens system or a plurality of electrons controlled by controller 10-1 via lead 27 and coordinated with the electron dose and voltage provided by emitter 11 There may also be an electron beam control mechanism 70 such as other systems of lenses. Thus, the electron beam 111 is scanned, focused, defocused, or on a target 1100 having one or more microstructures 700 manufactured in intimate thermal contact with the substrate 1000, or Otherwise it can be directed.

As illustrated in FIG. 7, the arrangement of the microstructures 700 is such that the impact of the plurality of microstructures 700 by the electron beam or the beam 111 is intensity in the viewing direction in a direction perpendicular to the surface normal of the target. May be arranged to cause release in a manner that increases or accumulates. That direction can also be selected by an opening 840 in the system screen 84 to form a directional beam 888 that exits the system through the window 40. In some embodiments, the opening 840 can be located outside the vacuum chamber, or more generally, the window 40 itself can serve as the opening 840 . In some embodiments, the opening can be inside the vacuum chamber.

FIG. 8 shows a target 1100 as may be used in some embodiments of the present invention. In this figure, a substrate 1000 has a region 1001 having an array of microstructures 700 including an X-ray generating material (typically a metal material) arranged in a regular array structure of right square pillars. In vacuum, the electrons 111 impact the target from above and generate heat and X-rays in the microstructure 700. The material of the substrate 1000 has a relatively low energy deposition rate for electrons compared to the material of the X-ray generating microstructure (typically selecting a low atomic number material for the substrate) Does not generate large amounts of heat and x-rays. The material of the substrate 1000 can also be selected to have a high thermal conductivity, typically greater than 100 W / (m ° C.), with the microstructure typically embedded within the substrate. That is, when the microstructure is formed as a quadrangular prism, at least five of the six surfaces are in close contact with the substrate 1000 so that heat generated in the microstructure 700 is effectively dissipated to the substrate 1000. It is preferable to have a mechanical contact. However, targets used in other embodiments may have fewer direct contact surfaces. In general, when the term “embedding” is used in this disclosure, at least half of the surface area of the microstructure is in intimate thermal contact with the substrate.

FIG. 9 shows another target 1100-F as may be used in some embodiments of the present invention, where the electron beam 111-F is directed by an electrostatic lens and is more focused. A spot is formed. In this situation, the target 1100-F still has a region 1001-F having an array of microstructures 700-F containing X-ray material, but the size and dimensions of this region 1001-F cause electron irradiation. Can match the region. In these targets, the “tuning” of the source shape and x-ray generating material can be controlled by the design to limit the amount of heat generated to the microstructure region 1001-F and also reduce design and manufacturing complexity. . This can be particularly useful when used with an electron beam that is focused to form a microspot, or when used by more complex systems that form more complex electron illumination patterns.

FIG. 10 shows another target 1100-E as may be used in some embodiments of the invention, where target 1100-E emits X-rays when exposed to electrons 111. FIG. Still have a region 1001-E with an array of microstructures 700-E containing X-ray material, but the region 1001-E is coplanar with the edge of the substrate 1000-E, Or it is arranged in the vicinity. This configuration may be useful with targets where emission at an angle close to 0 ° can be significantly attenuated in a configuration such as that shown in FIG. 8 because the substrate has a material that absorbs x-rays.

FIG. 12 shows the associated interaction between the electron beam 111 and a target having a substrate 1000 and a microstructure 700 of X-ray material. As illustrated, only three electron paths are shown, with two representative electrons impacting the two microstructures 700 shown, with one representative electron interacting with the substrate.

FIG. 13 shows the relative x-ray generation from the various regions shown in FIG. X-rays 888 have characteristic X-rays emitted from regions 248 in the plurality of microstructures 700 of the X-ray generating material from which they generate, and regions 1280 and 1080 where electrons interact with the substrate are Characteristic X-rays are generated (not characteristic X-rays of elements in the X-ray generation regions 248 of the plurality of microstructures 700 ). In addition, bremsstrahlung X-rays emitted from regions 248 of the plurality of microstructures 700 of the X-ray generating material typically occur in regions 1280 and 1080 where electrons encounter only low atomic number substrates. Is much stronger than the weak continuous X-rays 1088 and 1228 that emit.

In a broad target of substantive uniform materials, as X-rays are propagated to the surface through the material, the attenuation of X-rays between the multiple sources of target internal X-ray reduces the takeoff angle And increases due to the longer distance traveled through the material, often maximizing at or near the take-off angle of 0 °. Thus, any increase in brightness achieved by viewing near 0 ° can be balanced by reabsorption. The distance at which the X-ray beam decreases in intensity to 1 / e is called the X-ray attenuation length. Therefore, a configuration having a distance selected in relation to the x-ray attenuation length that does not allow the emitted x-rays to pass through as much further material as possible may be desired.

An illustration of some of the targets as may be used in some embodiments of the present invention is shown in FIG. In FIG. 14, an X-ray generation region having a single microstructure 2700 is configured at or near the recessed edge 2003 of the substrate in contact with the shelf 2002, similar to the situation illustrated in FIG. 11. doing. The X-ray generation microstructure 2700 has a rectangular bar shape with a width W, a length L, and a depth or thickness D embedded in the substrate 2000. When the X-ray generation microstructure 2700 is struck by electrons 111, Line 2888 is emitted.

An illustration of some of the alternative targets that may be used in some embodiments of the present invention is shown in FIG. In this target, an X-ray generation region having six microstructures 2701, 2702, 2703, 2704, 2705, 2706 is configured at or near the recessed edge 2003 of the target substrate 2000 in contact with the shelf-like portion 2002. And is similar to the situation illustrated in FIGS. As shown, the X-ray generation microstructures 2701, 2702, 2703, 2704, 2705, 2706 are arranged in a linear array of rectangular prisms that generate X-rays embedded in the substrate 2000 and are bombarded with electrons 111. X-rays 2888-D are emitted when

In this target as may be used in some embodiments of the present invention, the total volume of x-ray generating material is the same as in the previous illustration of FIG. The same applies to the case shown in FIG. 14, but the thickness D of the microstructure 2701-2706 (thickness along the surface normal of the target) is the X-ray generating material at the incident electron energy for optimum thermal performance. Is selected to be between 1/3 and 2/3 of the electron penetration depth. As in the case shown in FIG. 14, the width W of the microstructures 2701-2706 is selected to obtain the desired source size in the corresponding direction, and W is approximately 1 of D as illustrated. .5 times. As discussed previously, the bar width W can be substantially smaller or larger depending on the size of the desired source spot.

However, as shown, a single bar 2700 of length L as illustrated in FIG. 14 has been replaced with microstructures 2701, 2702, 2703, 2704, 2705, 2706 in the form of six subbars. , Each length l is L / 6. The volume of X-ray generation (when bombarded with the same electron density) is the same, but here each subbar has five faces that transfer heat to the substrate, and from X-ray generation subbars 2701-2706 Increase heat dissipation to the substrate. As illustrated, the separation distance d between the sub-bars is approximately equal to l, but larger or smaller dimensions may be used, which are the X-ray dose absorbed by the substrate and the X-rays Depends on the relative temperature gradient that can be realized between the particular material of the generated microstructure 2701-2706 and the substrate 2000.

In the configuration shown in FIG. 15 and the like, the total length of the plurality of X-ray generation sub-bars is generally about twice as long as the X-ray linear attenuation length in the X-ray generation material. Can be selected. Similarly, the thickness of the plurality of sub-bars D (thickness along the surface normal of the target), for optimum thermal performance, 1/3 of the electron penetration depth of X-ray generating material at an incident electron energy 2 / Although selected to be equal to 3, it can be substantially larger. The thickness D of the bar can also be selected to obtain a desired x-ray source size that is approximately equal in the relevant direction.

Bar multiple is be embedded (as shown) substrate, when the thermal load generated in the X-ray generating material is not too large, it may be disposed on the substrate.

In the targets of FIGS. 16A-16C , the plurality of microstructures are fabricated so as to be in intimate thermal contact with the substrate on five of the six faces. As illustrated, the top surfaces of the plurality of microstructures 700 are coplanar with the surface of the substrate, but other targets in which the plurality of microstructures are recessed may be fabricated, and the plurality of microstructures may be formed on the substrate. Other targets that exhibit local “bumps” to the surface may be manufactured.
Here, k is the thermal conductivity (W / (m ° C.)), and ΔT is the temperature difference (° C.) over the entire thickness d. Thus, an increase in surface area, a decrease in thickness, and an increase in ΔT all lead to a proportional increase in heat conduction.

FIGS. 18A-18C illustrate a region 1013 of a target having a checkered array of microstructures 700 and 701 in the shape of a rectangular prism containing an X-ray generating material, according to one embodiment of the present invention. . The array as shown is arranged as a buried array on the surface of the substrate 1000 . 18A shows a perspective view of 25 buried microstructures 700 and 701, FIG. 18B shows a top view of the same region, and FIG. 18C shows a side / sectional view of the same region with a recessed region indicated by a dotted line. ing.

An illustration of another target region 2001 as may be used in some embodiments of the present invention is shown in FIGS. 19A-19C and includes microstructures 2790 and 2791 comprising an x-ray generating material having a thickness D. A region 2001 of a target according to an embodiment of the present invention having an arrangement of The arrangement shown is a modified checkered pattern of rectangular prisms, but other configurations and arrangements of multiple microstructures may be used.

2. General Considerations for Linear Cumulative X-ray Sources FIG. 21 shows a collection of X-ray emitters arranged in a linear array. The long axis of the linear array extends from left to right in the figure, and the short axis extends in and out of the plane of the figure. Having one or more X-ray generating material, a plurality of X-ray generating elements 801, 802, 803, and 804, ... etc., at high voltages (anywhere from 1keV to 250 keV), electronic 1111,1112,1113,1114 , ... shocked by the beam, such as to form a sub-source which emits X-ray 818,828,838,848, ... the like. Although X-rays tend to be emitted isotropically, this analysis is for a viewpoint along an axis that passes through the center of the linear array of sub-sources, where a screen 84 having an opening 840 is placed. ing.

In a source design where all emitters emit X-rays of approximately the same intensity,
(This can be achieved if the array of X-ray emitting elements are of similar size and shape and are bombarded with electrons having similar energy and density). The total emission intensity is:

FIG. 22 shows the 1 / e attenuation length for three types of X-ray generating materials, namely, molybdenum (Mo), copper (Cu), and tungsten (W) for X-rays having energies ranging from 1 keV to 1000 keV, and three types of substrates. 1 / e decay length for X-rays with energies ranging from 10 keV to 400 keV for materials (graphite (C), beryllium (Be), water (H ₂ O)). [The data shown here was originally L. Henke, E.M. M.M. Gullikson, J. et al. C. According to Davis, “X-ray interactions: photoabsorption, scattering, transmission, and reflection at E = 50-30000 eV, Z = 1-92”, Atomic Data and Nuclear 2 pages 34-34. has been published (July 1993), <http: // henke. lbl. gov / optical_constants / atten2. It can be accessed at html>. Other X-ray absorption tables are <http: // physics. nist. gov / PhysRefData / XrayMassCoef / chap2. available at html>].

As an example using the values of FIG. 22, for 60 keV X-rays in tungsten, L _{1 / e} is approximately 200 microns, and the transmittance of an X-ray generating element having a width of 20 microns is given by the following equation.
For 60 keV X-rays on a beryllium substrate , L _{1 / e} is approximately 50,000 microns, and the transmittance of a 100-micron wide beryllium gap between a plurality of embedded tungsten X-ray generating elements is as follows: become.
Thus, for a periodic array of 20 micron wide tungsten elements embedded in a beryllium substrate and spaced apart by 100 microns, the best estimate of on-axis strength is:
This represents an order of magnitude increase in x-ray intensity when compared to a single tungsten x-ray emitting element.

As illustrated in FIG. 21 and as illustrated in FIG. 23A, electrons can impact a plurality of microstructure elements 801, 802, 803, etc. at normal incidence, as illustrated in FIG. 23B. The electron beams 1121, 1122, 1123, etc. are at an angle θ, and as illustrated in FIG. 23C, the electron beams 1131, 1132, 1133, etc. (such as a convergent electron beam) are at multiple angles, as illustrated in FIG. 23D. the electron beam 1141,1142,1143 at an angle θ from both sides, such as electron beam 1151,1152,1153 as illustrated in FIG. 23E have respectively different intensity or electron density, the illustrated in FIG. 23F Multiple elements in a uniform large-area electron beam 111 or any combination of many electron beam configurations that can be devised by those skilled in the art. It can shock the element.

The actual design of the pattern for electron irradiation may depend in part on the material properties of the x-ray generating material and / or the material filling the region between the plurality of x-ray generating elements. As illustrated in FIG. 23E, when the X-ray generating material is very absorbent, it must emit X-rays and travel the longest distance through the other plurality of X-ray generating elements. Greater electron density can be used to impact the. Similarly, as illustrated in FIG. 23B, when the electron penetration depth is deep, the X-ray generation material can be bombarded with oblique electrons. If the electron penetration depth is deeper than desired, a thinner region of x-ray generating material may be used to form the source with a smaller vertical dimension .

In many embodiments, the region of electron irradiation, electron beam or plurality of electron beams is primarily impact the X-ray generating element, in the region between these elements is adjusted so as not to shock obtain. In many embodiments, the spacing between the plurality of x-ray generating elements may be filled with a solid material that facilitates heat dissipation from the plurality of x-ray generating elements, rather than a vacuum. Such a source target having an array of multiple x-ray generating elements embedded in or embedded in a thermally conductive substrate such as diamond is described in copending US patent application Ser. No. 14 / 465,816, as described above. Which is incorporated by reference in its entirety.

A source having multiple electron beams used to independently bombard separate multiple x-ray generating elements can also be configured to allow different acceleration voltages to be used with different electron beam sources. . Such a source 80-B is illustrated in FIG. Also in this example, the previous high voltage source 10 is connected to the electron emitter 11-A that emits the electrons 111-A toward the target 1100-B via the conductor 21-A. However, two additional “boosters” for voltages 10-B and 10-C are also provided, and these high potentials are passed through the conductors 21-B and 21-C to electrons of different energy 111-B and 111-B. It is connected to additional electron emitters 11-B and 11-C that emit -C, respectively . The target 1100-B having X-ray generating elements 801, 802, 803,... Is usually set to a uniform ground potential, but individual electrons used to target different X-ray generating elements. beam source is obtained is set at different potentials, therefore, X-rays generating element 801, 802, 803 of electrons of different energies are different, ... can be used to impact the like.

In some embodiments, different x-ray generating elements may have different x-ray emitting materials, such as an axial view showing various spectral characteristic x-rays from different materials. A material that is relatively transparent to X-rays can be used at a location closest to the output window 840 (eg, the rightmost element 801 in FIG. 21), but a material that absorbs more strongly may be a plurality of other X It can be used for elements on the opposite side of the array so as not to attenuate the line sub- source too much.

FIG. 27 shows a diagram of this ratio for a wide range of x-ray energies for the three materials (Cu, Mo, and W). Once the X-ray generating material is selected for the desired characteristic line, this ratio is obtained is used to indicate a specific energy range (such as about the tungsten 55 keV), the figure of merit is comparatively large It may be configured so that the system operates so.

3.4. Time-Division X-Ray Generation In other embodiments, the X-ray generation elements 801, 802, 803, 804,... Do not need to be continuously impacted by electrons, but the electron beams 1211, 1212, 1213, 1214,... Can be switched on and off over time to distribute the thermal load. This can be particularly effective when viewed on an axis. This is because all X-rays appear to be emitted from the same source.

Furthermore, in some embodiments, the electron beam may simply scan across the target with the x-ray generating material. In some embodiments, this scan may be a regular raster scan, and in other embodiments, the scan may be “dwelled” or the x-ray generation area may be scanned at a slower rate. On the other hand, non-uniform scanning such as rapid movement from one X-ray generation region to the next X-ray generation region may be used. In other embodiments, electron beam, to provide all the simultaneous impact the X-ray generating region, or substantially impinging simultaneously a plurality of electron beam into a plurality of X-ray generating region, quickly turns on and off the electron beam Can be designed to form a “pulsed” X-ray source . This can have several advantages for some specific applications.

FIG. 29B shows emission from a plurality of microstructures, this time away from the incident electron beams 1111, 1112, 1113, and the like. In this example, the spacing between the microstructures 801, 802, 803,... Is much larger than their size, so that off- axis angles at which X-rays can propagate without attenuation by adjacent X-ray emitting elements. Is much smaller than the off-axis angle in the situation illustrated in FIG. 29A.

3.6. Multiple Independent Electron Beams Illustrated in FIGS. 30 and 31 (the target is shown in more detail) is a more general X-ray system 80 that incorporates some of the elements described above. -C. The system includes a plurality of electron emitters 11-A, 11-C that generate electron beams 111-A, 111-B, 111-C via a plurality of conductors 21-A, 21-B, and 21-C. The electronic system controller 10-V which sends various voltages to B and 11-C is provided. Each of these electron beams 111-A, 111-B, and 111-C is connected to a plurality of electron lenses 70-A, 70-B, and 70 via conductors 27-A, 27-B, and 27-C. It can be controlled by a signal from the system controller 10-V that controls -C.

As illustrated, the system further comprises a cooling system. The cooling system typically has a container 90 filled with cooling fluid 93 is water, the cooling fluid 93 by a mechanism 1209 such as a pump, a part of the plurality you pass through the substrate 1000 of the target 1100-C It is moved through the cooling path 1200.

FIG. 31 shows a portion of the target 1100-C under impact by electrons in an enlarged view of the system, into which two additional electron beams 111-D and 111-E have been added. Yes. As illustrated, both beams 111-D and 111-E have a higher current than the right three electron beams 111-A, 111-B, and 111-C, and the leftmost electron beam 111 -E has the highest current density of all the beams, indicating that the beams need not be of equal density. The leftmost X-ray generating elements 804 and 805 that receive a higher current are between them and the adjacent microstructures, between the rightmost elements 801, 802, and 803 that receive a lower electron current. It is also illustrated that it has a larger interval than that provided in FIG. In some embodiments, 804 and 805 can be composed of a material with a higher atomic number than 801, 802, and 803.

FIG. 31 also shows a conductive overcoat film 770 that serves both as thermal conductivity (to remove heat) and conductivity, and is provided with a return path for electrons to the ground 722. Also shown is a screen 84 having an opening 840 to allow on-axis X-rays to be emitted from the target.

It should also be noted that the two-surface target described above can also be used in one embodiment with a rotating anode in which the anode rotates to dissipate heat. A system 580-R having these features is illustrated in FIG. In this embodiment, many elements are the same as in a conventional rotating anode system as illustrated in FIG. 6A, but in this embodiment as illustrated, the controller 10-3 is connected to a conductor 21- through F and 21- G, and supplies a high voltage to each of the electron beam 2511-F and 2511-G to emit each of the two emitters 11-F and 11-G. These electron beams impact both sides of the chamfered portion of the target 500-R, coated on both sides with coatings 2521 and 2522 having an X-ray generating material that generates X-rays 2588. It should also be clear that multiple embodiments with additional controls may be designed, such as multiple electron lenses to steer the beam or openings to define the x-ray beam output.

4.3. FIG. 36 shows another embodiment, where multiple targets have multiple microstructures of x-ray generating material embedded in a substrate instead of a thin coating. Have.

In general, the relationship between the target and the lens is established at the time of manufacture. Lens, in either the particular mount or epoxy designed for use in a vacuum, and by using the procedure of positioning, such as are well known to those skilled in the optical manufacturing, a predetermined position Can be fixed to. As previously described, final alignment is achieved by placing an x-ray detector at the output aperture and adjusting the focus and position of the various electron beams to achieve maximum x-ray intensity. Can be realized. Final adjustments can also be made for alignment of multiple optical elements using X-rays. It should be noted that the detector can also be used to provide feedback to the electron beam controller. For example, the detector provides a measurement of the spectral output that can then be used to instruct the electron beam that generates a particular characteristic line to increase or decrease its output.

All targets, may not necessarily an electron of the same incident angle should give al is an impact, it should be noted. In configurations having multiple x-ray emitting materials, different materials may have different penetration depths. Thus, bombarding with electrons of different angles of incidence can be more efficient for generating X-rays for that particular target. Also, as described in previous embodiments, different electron densities, energies, angles, focus states, etc. can be used for different targets.

It should be noted that emission occurs isotropically from all targets and that multiple x-ray lenses that collect and focus on the x-rays that propagate in both directions. Thus, a detector placed at the opposite end of a series of targets can serve as a calibration of the X-ray system and monitor the overall output.

5.2. Walter Lenses and Other Multi-Element X-Ray Lenses Another embodiment of the present invention is illustrated in FIG. In this embodiment, optical elements 2921 and 2931 that collect X-rays emitted from one target and focus it downstream in focus are optical elements now known as Walter lenses. A Walter lens is a well-known system of nested mirrors that collects and focuses X-rays, typically using parabolic and / or hyperbolic reflective surfaces, typically used at glazing angles, respectively. It has with the element of. Typically, the reflective surface is glass. The glass surface can be coated with a high mass density material or an X-ray multilayer (typically made using molybdenum (Mo) and silicon (Si) layers).

43A and 43B show a prior art embodiment of a multi-element lens used for x-rays with various curved lenses arranged in both horizontal and vertical directions. As mentioned above, the materials and coatings used for these optical elements can be selected to match the spectrum of x-rays expected to be emitted from various x-ray sources.

5.3. Another embodiment of a polycapillary lens present invention is illustrated in Figure 44. In this embodiment, the optical elements 2941 and 2951 that collect X-rays emitted from one target and focus it downstream in focus are optical elements now known as polycapillary lenses. Polycapillary lenses are similar to optical fibers in that X-rays are guided through a thin fiber and appear at the other end of the desired location. However, unlike optical fibers with solid glass fibers that reflect using total internal reflection, polycapillary lenses have multiple hollow tubes and X-rays are directed into the tube by external reflection from the material at the glazing angle. The

5.4. Variations particular option, reflecting lens, Worutarenzu, or have been shown in several examples showing the polycapillary lens, which are not meant to be limiting in any way. The optical configurations illustrated in FIGS. 39 to 42 and 44 may be interchangeable with, for example, a Walter lens 2931 that replaces the mirrors 2821 and 2822 of FIG. Multiple targets with multiple microstructures are used in these examples, but multiple targets with multiple thin films, such as illustrated in FIGS. 33 and 35, together with these X-ray lenses that focus at the focal point It should also be noted that it can be used.

For example, although it has been described that the conductive layer is deposited before the cap layer is deposited , a combination of these functions (ie, a conductive cap layer) is used , such as that illustrated in Appendix 19 . Similarly, some of the multiple process steps may be repeated to deposit multiple layers of target material as illustrated in appendix 18.

Claims (60)

A vacuum chamber;
An X-ray transmissive window attached to the wall of the vacuum chamber;
At least one electron beam emitter in the vacuum chamber;
At least one target,
A substrate having a first selected material;
A plurality of discrete structures having a second material selected for its X-ray generation characteristics;
Having at least one target having:
Prepared,
Each of the plurality of discrete structures is in thermal contact with the substrate;
At least one of the plurality of discrete structures has a thickness less than 10 microns, and the lateral dimension of each of the at least one of the plurality of discrete structures is less than 50 microns,
X-ray source. The plurality of discrete structures are embedded in a surface of the substrate;
The X-ray source according to claim 1. The plurality of discrete structures are embedded within a depth of less than 100 microns of the surface of the substrate;
The X-ray source according to claim 1 or 2. Means for directing an electron beam emitted from the emitter onto the target;
The X-ray source according to any one of claims 1 to 3. The means for directing the electron beam comprises a plurality of electron lenses;
The X-ray source according to claim 4. The means for directing the electron beam comprises a plurality of electrostatic lenses;
The X-ray source according to claim 4 or 5. The means for directing the electron beam comprises a plurality of magnetic lenses;
The X-ray source according to claim 4 or 5. The means for directing the electron beam includes focusing, diverging, defocusing, scanning, raster scanning, pausing, hiding, sweeping, changing beam direction, beam Allows control of the electron beam by operations selected from the group consisting of changing the intensity profile, forming multiple electron beams, changing the beam current density, and changing the acceleration of electrons in the electron beam. ,
The X-ray source according to any one of claims 4 to 7. The means for directing the electron beam makes it possible to focus the electron beam to a spot size smaller than 30 microns in at least one dimension;
The X-ray source according to any one of claims 4 to 8. The means for directing the electron beam enables directing the electron beam into a pattern corresponding to a position of at least a portion of the plurality of discrete structures;
The X-ray source according to any one of claims 4 to 9. The means for directing the electron beam enables directing the electron beam into a pattern corresponding to a position of at least a portion of the plurality of discrete structures;
The pattern is adapted in time in response to a signal from a detector that monitors a plurality of predetermined characteristics of the emitted X-ray.
The X-ray source according to claim 10. The predetermined properties of the emitted X-ray are selected from the group consisting of brightness, brightness, total intensity, flux, energy spectrum, beam profile, and beam spread;
The X-ray source according to claim 11. The plurality of discrete structures are arranged in a linear array;
The X-ray source according to any one of claims 1 to 12. The plurality of discrete structures are manufactured to have similar shapes;
The X-ray source according to any one of claims 1 to 13. The similar shape is selected from the group consisting of a regular prism, a rectangular prism, a cube, a triangular prism, a trapezoidal column, a pyramid, a tetrahedron, a cylinder, a sphere, an egg, and a barrel.
The X-ray source according to claim 14. The first selection material is selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.
The X-ray source according to any one of claims 1 to 15. The second material is aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum. Selected from the group consisting of tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
The X-ray source according to any one of claims 1 to 16. The subset of the plurality of discrete structures has a third material selected for its x-ray generation characteristics;
The X-ray source according to any one of claims 1 to 17. The third material is aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum. Selected from the group consisting of tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
The X-ray source according to claim 18. At least one of the plurality of discrete structures is disposed within 500 microns from an edge of the substrate;
The X-ray source according to any one of claims 1 to 19. The linear array is defined to have a major axis and a minor axis, the major axis of the linear array is aligned with the window, and the angle between the major axis and the surface normal of the window is Less than 85 ° at the intersection of the long axis and the window,
The X-ray source according to claim 13. At least one of the plurality of discrete structures is disposed within 500 microns from an edge of the substrate closest to the window;
The X-ray source according to claim 21. When the plurality of discrete structures of the target are exposed to the directed electron beam, X-rays emitted by a predetermined one of the plurality of discrete structures are Aligned to penetrate another,
The X-ray source according to any one of claims 4 to 22. When the target is exposed to the directed electron beam, X-rays emitted by a predetermined number of discrete structures among the plurality of discrete structures are selected from the plurality of discrete structures. Aligned to penetrate one predetermined discrete structure;
The X-ray source according to any one of claims 21 to 23. A cooling system,
A container for storing the cooling fluid;
A path in the substrate for carrying the cooling fluid;
An additional path for carrying the cooling fluid from the container to the path in the substrate;
An additional path for carrying the cooling fluid from the path in the substrate to the container;
A pumping mechanism for pumping the cooling fluid through the cooling system;
The cooling system further comprising:
The X-ray source according to any one of claims 1 to 24. A mechanism for rotating the target;
The X-ray source according to any one of claims 1 to 25. A vacuum chamber;
A first window transparent to x-rays attached to the wall of the vacuum chamber;
One or more electron emitters in the vacuum chamber;
Multiple X-ray targets
Prepared,
Each target has a material selected for its x-ray generation characteristics,
At least one size of the material is less than 20 microns;
The one or more electron emitters and the plurality of X-ray targets are aligned such that an electron bombardment on the plurality of X-ray targets generates a plurality of X-ray sub-sources, thereby A line sub-source is aligned along an axis passing through the first window;
X-ray source. The materials selected for their X-ray generation properties are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium Selected from the group consisting of silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
The X-ray source according to claim 27. For a predetermined X-ray energy spectrum, the transmittance of at least one of the plurality of X-ray targets is greater than 50%;
The X-ray source according to claim 27 or 28. The predetermined X-ray energy spectrum corresponds to an emission spectrum of at least one X-ray sub-source;
30. The x-ray source of claim 29. At least one of the plurality of X-ray targets further includes a substrate.
The X-ray source according to any one of claims 27 to 30. The substrate comprises a material selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon;
The X-ray source according to claim 31. The X-ray generating material is on the substrate in the form of a thin film;
The X-ray source according to claim 31 or 32. The target has a plurality of discrete structures embedded in a substrate having a material with a thermal conductivity greater than 0.1 Wm ^-1 ° C ^-1 ;
The plurality of discrete structures have materials selected for their x-ray generation characteristics;
The X-ray source according to any one of claims 27 to 30. Means for directing an electron beam from at least one of the plurality of electron emitters to one or more locations on the target to form a plurality of X-ray sub-sources;
35. The x-ray source of claim 34. The means for directing the electron beam comprises a plurality of electron lenses;
36. The x-ray source of claim 35. The plurality of X-ray sub-sources generated by the impact of the plurality of electron beams on the plurality of targets are aligned along an axis passing through the first window. Means for aligning each of the electron beams;
37. An X-ray source according to any one of claims 34 to 36. At least two adjacent X-ray sub-sources share a common substrate;
The X-ray source according to any one of claims 27 to 37. Further comprising an X-ray optical element;
The x-ray optical element is arranged such that x-rays emitted by a sub-source are directed by the x-ray optical element onto an adjacent x-ray sub-source;
The X-ray source according to any one of claims 27 to 38. The x-ray optical element has a grazing incidence x-ray reflector;
40. The x-ray source of claim 39. The x-ray optical element comprises an x-ray reflector having a multilayer coating;
41. The x-ray source according to claim 40. The x-ray optical element has a coated x-ray reflector having a thickness greater than 20 microns and comprising a high mass density material;
41. The x-ray source according to claim 40. The X-ray optical element has a Walter lens;
41. The x-ray source according to claim 40. The X-ray optical element has a polycapillary lens;
41. The x-ray source according to claim 40. The X-ray optical element has an ellipsoidal capillary lens arranged such that a plurality of focal points correspond to the center of two adjacent sub-sources.
41. The x-ray source according to claim 40. Further comprising an X-ray optical element;
The X-ray optical element is arranged such that X-rays emitted by a sub-source enter the X-ray optical element and are directed over a predetermined location in the vacuum chamber.
41. The x-ray source according to claim 40. A second window transparent to X-rays attached to the wall of the vacuum chamber;
The plurality of x-ray sub-sources are aligned along a line passing through both the first window and the second window;
47. An X-ray source according to any one of claims 27 to 46. Further comprising an X-ray detector;
The x-ray detector is aligned such that the x-ray emitted by at least one of the plurality of x-ray sub-sources strikes the x-ray detector;
48. The x-ray source of claim 47. A vacuum chamber;
A first window transparent to x-rays attached to the wall of the vacuum chamber;
A first electron beam emitter in the vacuum chamber;
A second electron beam emitter;
A target,
A substrate,
A first structure having a material selected for its X-ray generation characteristics;
A second structure having a material selected for its X-ray generation properties;
Having a target,
Prepare
X-ray source. Multiple pairs of electron beam emitters;
Multiple targets,
A substrate,
A first structure having a material selected for its X-ray generation characteristics;
A second structure having a material selected for its X-ray generation properties;
Having a plurality of targets,
In addition,
50. The x-ray source of claim 49. The material of the first structure and the material of the second structure are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium. Selected from the group consisting of ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof;
The X-ray source according to claim 49 or 50. The substrate comprises a material selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon;
52. The X-ray source according to any one of claims 49 to 51. At least one of the first structure and the second structure is a thin film coating on a surface of the substrate;
53. An X-ray source according to any one of claims 49 to 52. The first structure and the second structure are both thin film coatings on both surfaces of the substrate.
54. An X-ray source according to any one of claims 49 to 53. At least one of the first structure and the second structure has one or more microstructures;
55. An X-ray source according to any one of claims 49 to 54. The one or more microstructures are embedded in the substrate;
56. The X-ray source according to claim 55. One or more microstructures are embedded in an opposite surface of the substrate relative to at least one of the other microstructures;
57. The x-ray source according to claim 56. The first electron beam emitter and the second electron beam emitter are aligned to bombard both surfaces of the target with a plurality of electron beams.
50. The x-ray source of claim 49. A method for generating X-rays,
Exposing at least one target to an electron beam formed to strike a plurality of discrete structures;
The at least one target is
A substrate having a first selected material;
The plurality of discrete structures having a second material selected for its x-ray generation characteristics;
Have
Each of the plurality of discrete structures is in thermal contact with the substrate;
At least one of the plurality of discrete structures has a thickness of less than 10 microns;
The lateral dimension of each of the at least one of the plurality of discrete structures is less than 50 microns;
Method. A method for generating X-rays,
Exposing a plurality of targets having x-ray generating material contained in a single vacuum chamber to a plurality of electron beams;
The positions of the plurality of electron beams are adjusted to increase the intensity of the X-rays emitted from the plurality of targets and also passing through a predetermined opening.
Method.