JP6659025B2 - X-ray source - Google Patents

Description

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

  Embodiments disclosed herein relate to a high intensity source of X-rays. Such high intensity sources may be useful in a variety of applications where X-rays are used, including manufacturing inspection, metrology, crystallography, structure / composition analysis, and medical imaging / diagnostic systems.

First discovery of X-rays by X-ray in 1896 [W. C. Rongen, "Eine Neut von Strahlen" (Wiirzburg Verlag, 1895); "On a New Kind of Rays", Nature, Vol. 53, pages 274-276 (January 23, 1896), Rentgen vacuum I was born by accident when I was experimenting with the target's electron bombardment. 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 routinely used for scientific applications such as

  Experimental X-ray sources were subsequently improved by Coolidge in the early 20th century [see, for example, William D.A. U.S. Pat. Nos. 1,211,092 (issued on Jan. 2, 1917), 1,917,099 (issued on Jul. 4, 1933), and 1,946, issued by Coolidge. No. 312 (published February 6, 1934)], and in the latter half of the twentieth century, a system was developed to generate a very strong X-ray beam using a synchrotron or a free electron laser (FEL). . However, these synchrotron and FEL systems are physically very large systems, and their installation requires 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.

One example of the simplest X-ray source, the transmitted X-ray source 08, is illustrated in FIG. The source generally comprises a sealed vacuum tube 02 or a vacuum environment provided by constant evacuation (typically 10 ⁻⁶ Torr or higher vacuum), the negative and positive electrodes of a high voltage source 10 outside the tube. Are manufactured with sealed conductors 21 and 22 leading to various elements inside the vacuum tube 02. The source 08 typically includes a plurality of mounts 03 for fixing the vacuum tube 02 in the housing 05, and the housing 05 is made of lead or the like to prevent X-rays from being emitted by the source 08 in unnecessary directions. May additionally be provided.

Inside the vacuum tube 02, the emitter 11 connected to the high voltage source 10 through the conductor 21 acts as a cathode, and in many cases, generates a beam of electrons 111 by applying a current to the filament. The target 01 is electrically connected to the opposite high voltage conductor 22, thereby acting as an anode. The emitted electrons 111 accelerate toward the target 01 and collide with the target 01 with high energy having electron energy determined by the magnitude of the acceleration voltage. Impact of the electrons 111 on the solid target 01 causes a number of effects, including the emission of X-rays 888. Some of the x-rays 888 exit 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 mounted directly 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 window 04 itself.

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

Inside the vacuum tube 20, an emitter 11 connected to the high voltage source 10 via a conductor 21 acts as a cathode, and in many cases, generates a beam of electrons 111 by passing a current through the filament. The target 100 supported by the target substrate 110 is electrically connected to the opposite 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 the electrons 111 with the target 100 causes a number of 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.

  In another prior art embodiment of a reflected x-ray source (not shown in FIG. 2), the target 100 and the substrate 110 can be integrated or comprise a solid block of the same material, such as copper (Cu) I can do it. Although not shown in FIGS. 1 and 2, in practice, as commonly used, a plurality of electronic lenses (electrostatic or electromagnetic) are provided to guide and shape the path of the electrons to provide more focus. A focused beam can be formed on the target. Similarly, an electron source with a plurality of emitters is provided, which may provide a larger distributed source of electrons.

  When the electrons collide with the target 100, the electrons may interact in several ways. These are illustrated in FIG. The electrons in the electron beam 111 collide with the target 100 at its surface 102 and the electrons passing through the surface multiply their energy by multiplying the footprint (area) of the incident electron beam by the electron penetration depth. Communicate to a target 100 within an interaction volume 200 that is generally defined. For very small sized incident electron beams (eg, beam diameters less than 100 nm), the interaction volume 200 is typically in the form of a “pear” or “tear” in three dimensions, and the direction of electron propagation Form a symmetrical shape around. For larger beams, the interaction volume uses the transverse beam intensity profile and is represented by this "tear" shaped convolution.

The equation commonly used to estimate the depth of penetration of electrons into a material is Pot's Law [P. J. Potts, 1987, Springer Netherlands, "A Handbook of Silicate Rock Analysis," Chapter 10, "Electron Probe Microanalysis," p. 336, according to which the depth in units of micron, k, is in units of k, where x is the depth in k of e. It is stated that it is related to 10% of the value obtained by raising the electron energy E ₀ to the power of 3/2 and dividing by the material density.
For less dense materials, such as diamond substrates, the penetration depth will be much greater than for denser 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 cause the generation of secondary electrons that are typically detected from regions 221 located near the surface, while some of the electrons are backscattered This may be detected from a somewhat larger area 231 due to these high energies.

  X-rays 888 are generated and emitted outward in all directions throughout the interaction volume 200, including the near-surface regions 221 and 231 and extending approximately three times into the target 100. X-ray emission can have a complex energy spectrum. When electrons penetrate the material, they slow down and lose energy. Thus, different portions of the interaction volume 200 will generate multiple X-rays having different properties. 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 emissions 388 arise from electrons that have diverted from their original orbit, but it depends on how close the electrons pass 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. Since a wide range of deflections and decelerations can occur, due to the approximate statistics of electron collisions with atoms of the target material, the change in energy is continuous, and thus the energy of the generated X-rays is also continuous. Larger emissions occur on the lower energy side of the energy spectrum, and much less on the higher energy side, reaching the absolute limit where there are no X-rays with energies greater than the original electron energy (100 keV in this example). . Due to the etymology of electron deceleration, this type of continuous x-ray emission 388 follows the German word "bremsen" for "braking" and is commonly referred to as bremsstrahlung.

  These continuous X-rays 888 are generated throughout the interaction volume, shown as the largest shaded portion 288 of the interaction volume 200 in FIG. At lower energies, the bremsstrahlung x-rays 888 are typically emitted isotropically, i.e., with little change in intensity with respect to the emission direction [see, e.g. Gonzales, B.A. Cavness, S.M. Angular distribution of thick-target bremstrahlung produced by electronics with initial energy aging aging from 20 years by William. Rev .. A, 84, 052726 (2011)]. Higher energy excitation may increase the "0 degree" emission normal to the electron beam, ie, for an incident beam at 90 degrees to the target surface. [For example, J. G. FIG. Chevenak, A .; Liuzzi, "Experimental thick-target blemstrahlung spectrum from electrons in the range 10 to 30 keV", Phys. Rev .. A, 12 (1), pages 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 to attenuate low energy X-rays, such as a sheet or layer of aluminum, to produce the modified energy spectrum 488 shown in FIG.

  When the electron energy is greater than the binding energy of the inner shell (core-shell) electrons of the elements in the target, electrons can be emitted (ionized) from the shell, creating vacancies. The less strongly coupled outer shell electrons can then freely transition into the inner shell vacancies, filling the vacancies. As the filling electrons move to lower energy levels, extra energy is emitted in the form of X-ray photons. This emission is known as a "characteristic" emission because the energy of the photon is characteristic of the chemical element that generates the photon.

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 vacancy is filled with electrons in the L-shell, having a binding energy of 10.2 keV, 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 = 67.2keV. Multiple separations can occur at various levels and cause small changes in energy, for example, _Kβ1 , _Kβ2 , _Kβ3 .

  Since these discrete emission lines depend on the atomic structure of the target material, the emission is generally referred to as a "characteristic line". This is because the “characteristic line” indicates the characteristic 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. The 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 three to five times the ionization energy of the core electrons.

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

  For some applications, X-rays having a broad spectrum may be appropriate. In other applications, a monochromatic source may be desired or even needed for the required sensitivity or resolution. In general, the composition of the target material is selected to provide an X-ray spectrum having 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 altered by changing the accelerating voltage), the choice of x-ray target material, and the shape of x-ray collection from the target. Can be controlled.

X-rays may be emitted isotropically, as illustrated in FIG. 3, but as shown in FIGS. 5A-5C, the 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, per solid angle (mrad ² ), and the area of the X-ray source (mm ² ) (for some measurements, a 0.1% bandwidth window is included in the definition) X-ray intensity (sometimes referred to as "brilliance") is an important figure for the source because it is related to obtaining a good signal-to-noise ratio for downstream applications. It is of merit.

  Brightness can be increased by adjusting geometric factors to maximize the x-rays collected. As illustrated in FIGS. 5A-5C, the surface of the target 100 of the reflective x-ray source is mounted at a generally angle θ (as also shown in FIG. 2) to provide bombardment by the dispersed electron beam 111. receive. Emission through window 440 is five equally spaced 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 high angle θ source, the brightness is reduced because the five spots are wider for a solid angle centered on window 440. On the other hand, at low angles θ, the five source spots appear to be closer together, thus emitting more X-rays within the same solid angle, resulting in increased brightness.

  In principle, a source mounted at [theta] = 0 [deg.] Can be considered to have the highest possible brightness since all the sources can be apparently superimposed and accumulated on the emitted X-rays. In practice, emission at 0 ° occurs parallel to the surface of a solid metal target for a conventional source, and x-rays are generated because the x-rays must propagate along a long distance of the target material before emission. Most of the X-rays are attenuated (re-absorbed) 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 the maximum practical brightness and reduces the apparent size of the source. It condenses 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 as viewed along the direction in which the x-rays are collected for use, ie, along the axis of the x-ray beam. Due to the limited electron penetration depth, the effective source area of the incident electron beam having a size comparable to or greater than the electron penetration depth is the distance between the axis of the X-ray beam and the surface of the target. Angle (referred to as the “take-out 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, for wide flat targets, this advantage is limited. The reason is that as the X-rays propagate to the surface, the absorption of the X-rays from the X-ray generation point inside the target increases, and the absorption of the X-rays increases as the extraction angle becomes smaller. Typically, a compromise angle between lower angle brightness enhancement and re-absorption brightness reduction reached an extraction angle of about 6 °.

Another way to increase the brightness of the X-ray source for bremsstrahlung is to use a higher atomic number Z target material. The reason is that the higher the atomic number of the material, the higher the efficiency of X-ray generation for bremsstrahlung. 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 atomic number Z of 74. Table 1 shows the X-ray targets, a plurality of further possible target materials (particularly useful for the particular characteristic line of interest), and a plurality of commonly used materials for some materials that may be used as substrates for the target material. Are described. The melting point and the thermal / electrical conductivity show values near 300 K (27 ° C.). Most of the values are taken from the 90th edition of CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, 2009. Other values have been quoted from various sources found on the Internet. Note that for some materials, such as, for example, sapphire, thermal conductivity may be an order of magnitude greater when cooled to a temperature below liquid nitrogen temperature (77 K) [see, e.g. R. See Dobbovinskaya et al., "Sapphire: Material, Manufacturing, Applications," Springer Science + Business Media, LLC (2009), Chapter 2.1.5, "Thermal Properties"].

  Other methods of increasing the brightness of the X-ray source include increasing the overall current or focusing the electron beam on a smaller spot, for example using multiple electron lenses, or either. Increasing the electron energy by increasing the density or increasing the accelerating voltage (this increases the x-ray generation per unit electron energy deposited on the target, and more in the characteristic line) Release can also occur).

  However, all of these improvements have limitations 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 surface convection air cooling can occur. If excessive heat is generated in the target, the target material may undergo a phase change and even melting and evaporation. Thermal management techniques are important tools for making better x-ray sources, since most of the energy deposited on the target by the electron beam becomes heat.

  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 with a target anode 500 that typically rotates between 3,300 and 10,000 rpm. The target anode 500 is connected by a shaft 530 to a rotor 520, which is supported through its mount 522 by a conductive bearing 524 that connects to the conductor 22 and the positive electrode of the high voltage source 10. The rotation of rotor 520, shaft 530, and anode 500, all within vacuum chamber 20, is typically driven inductively by stator windings 525 mounted outside the vacuum.

  FIG. 6B shows the surface of the target anode 500 in more detail. The edge 510 of the rotating target anode 500 may be beveled obliquely, and the source of the electron beam 511 is positioned to direct the electron beam to the chamfered edge 510 of the target anode 500, and the target spot X-rays 888 are generated from 501. The target spot 501 is heated because it generates X-rays, but as the target anode 500 rotates, the heated spot moves away from the target spot 501, where the electron beam 511 irradiates a cooler portion of the target anode 500. The hot spot has one revolution time to cool before being heated again when passing through the hot spot 501. By continuously rotating the target anode 500, the X-rays are generated from a single fixed spot, but the total area of the target illuminated by the electron beam is substantially larger than the electron beam spot and the electron energy Is effectively spread 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 substrate with high thermal conductivity. For electrons with energies up to 100 keV, due to the thin interaction volume, the target material itself need not be thicker than a few microns and can be deposited on a substrate such as diamond, sapphire, or graphite, which quickly dissipates heat. However, as shown in Table 1, diamond has very low electrical conductivity, so any anode design made on a diamond substrate will require an electrical connection 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 diamond is, for example, K. Upadya et al., U.S. Patent No. 4,972,449; U.S. Patent No. 5,148,462 to Spitsyn et al. Described in US Pat. No. 6,850,598 to Fryda et al.].

  The substrate may also have multiple paths 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 (see, for example, US Pat. , 602,899). Water cooled anodes have been used for various 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 heat transfer properties. Heat sinks may also have multiple paths for coolant to reject heat (see, for example, US Pat. No. 8,094,784 to Edward J. Morton). In some cases, thermoelectric coolers or cryogenic systems have been used to provide additional cooling to X-ray targets attached to heat sinks. Again, all are aimed at achieving high X-ray brightness without melting or damaging the target material due to overheating.

  Another approach to mitigating heat for microfocus sources is to use a target created by a jet of liquid metal. The electrons bombard the conductive jet of liquid gallium (atomic number 31), and the heated gallium flows out of the electron irradiation volume together with the jet, thereby enabling a high current density. [For example, M. Otendal et al., "A9 keV electron-impact liquid-gallium-jet x-ray source", Rev. Sci. Instrument, 79, 016102, (2008)].

Although it is effective in a particular environment, there is still room for improvement. Liquid metal jets require sophisticated water supply and drainage systems and consumables, limit the materials used (and thus the atomic number values and their associated spectra), and make it difficult to ramp up to higher powers. In the case of a thin film target of a uniform solid material 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. Thermal conduction only occurs through the bottom of the membrane. At the lateral dimensions, there are the same conduction problems that exist with bulk materials.

  Thus, while 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 flow densities, it is still insufficient to accommodate laboratory or desk environments, or portable. It is so small that it is even useful for the device. Such bright sources may enable 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 can have orders of magnitude brightness compared to existing commercial X-ray technology. Higher brightness is achieved to some extent by using a novel configuration for X-ray targets used to generate X-rays from electron beam bombardment. The configuration of the x-ray target is such that it is in intimate thermal contact (such as embedded or embedded therein) with a high thermal conductivity substrate so that heat is more efficiently dissipated from the x-ray generating material. May have multiple microstructures of one or more selected X-ray generating materials. This, in turn, allows for bombardment of high electron density and / or high energy electrons with the X-ray generating material, resulting in greater X-ray brightness.

  A great advantage of some embodiments is that the placement of multiple microstructures allows for 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 also be used to align an “0 °” X-ray emission. Straight line accumulation of x-rays from multiple sources results in greater x-ray brightness.

  Some embodiments of the present invention collect multiple x-ray optics that collect the x-rays emitted from one structure, refocus it and superimpose the x-rays from a second structure. Be prepared. This X-ray relay can also provide greater X-ray brightness.

  Some embodiments of the present invention include 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 the microstructured pattern of targets to further dissipate heat and increase the cumulative X-ray brightness.

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

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

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

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

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

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

2 shows X-ray emission from a prior art target when the target is tilted at 30 °.

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

FIG. 4 illustrates a perspective view of a target having a grid-like embedded rectangular target microstructure on a large substrate that may be used in some embodiments of the present invention.

FIG. 4 shows a perspective view of a variation of a target having a grid-like embedded rectangular target microstructure on a large substrate for use with a focused electron beam, which may be used in some embodiments of the present invention.

FIG. 4 shows a perspective view of a variation of a target having a grid-like embedded rectangular target microstructure on a cutting substrate that may be used in some embodiments of the present invention.

FIG. 4 shows a perspective view of a variation of a target having a microstructure of a grid-like embedded rectangular target on a substrate with a shelf-like recess, which may be used in some embodiments of the present invention.

FIG. 4 illustrates a cross-sectional view of electrons incident on a target having a target microstructure on a large substrate, which may be used in some embodiments of the present invention.

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

FIG. 3 illustrates a perspective view of a target having a single rectangular microstructure disposed on a substrate having a recessed area, which may be used in some embodiments of the present invention.

FIG. 3 illustrates a perspective view of a target having a plurality of rectangular microstructures arranged in a row on a substrate having a recessed area, which may be used in some embodiments of the present invention.

FIG. 3 shows a perspective view of a target having a microstructure of a grid-like embedded rectangular target that may be used in some embodiments of the present invention.

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

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

FIG. 17 shows a cross-sectional view of the target of FIG. 16, showing the transfer of heat to a thermally conductive substrate that has been subjected to electron beam irradiation.

FIG. 3 illustrates a perspective view of a target having an embedded target microstructure in a checkered configuration that may be used in some embodiments of the present invention.

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

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

FIG. 4 illustrates a perspective view of a target having a microstructure of a grid-like embedded rectangular target disposed on a stepped substrate, which may be used in some embodiments of the present invention.

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

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

FIG. 19C illustrates a side / cross-sectional view of the target of FIG. 19C emitting 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.

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

FIG. 3 illustrates a linear array of x-ray emitters that are exposed to a normal incidence electron beam, which may be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of X-ray emitters that are exposed to an electron beam incident at an angle θ that may be used in some embodiments of the present invention.

FIG. 4 illustrates a linear array of X-ray emitters that are exposed to a focused electron beam that may be used in some embodiments of the present invention.

FIG. 3 illustrates a linear array of x-ray emitters that are exposed to an electron beam incident at an angle θ from multiple directions, which may be used in some embodiments of the present invention.

1 illustrates a linear array of X-ray emitters that are exposed to electron beams of various electron densities, which may be used in some embodiments of the present invention.

FIG. 4 illustrates a linear array of X-ray emitters that are exposed to a uniform electron beam, which may be used in some embodiments of the present invention.

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

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

FIG. 4 shows a plot of tungsten decay length and CSDA (continuous deceleration of electrons) over a range of X-ray energies.

FIG. 4 shows a plot of the decay length to CSDA ratio of tungsten over a range of X-ray energies.

FIG. 4 shows a diagram of the decay length to CSDA ratio of a plurality of materials over a range of X-ray energies.

FIG. 3 illustrates a collection of X-ray emitters arranged in a linear array at time step t = 0 in time-shared electron beam irradiation, which may be used in some embodiments of the present invention.

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

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

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

FIG. 3 illustrates off-axis emission of x-rays 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-section of one embodiment of an X-ray system according to the invention, comprising a plurality of electron emitters and a cooling system.

31 shows a cross section of a target of the X-ray system of FIG. 30.

1 shows a schematic cross-section of an embodiment of an X-ray system according to the invention with a two-sided target.

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

1 shows a schematic cross-sectional view of an X-ray system according to one embodiment of the present invention, comprising a plurality of electron emitters impacting on the sides of a rotating anode.

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

2 shows a cross section of a plurality of targets having a plurality of microstructures of X-ray generating material, aligned for line accumulation used in the system according to the invention.

FIG. 2 illustrates a side view of a target having an X-ray coating that can be bombarded with a dispersed electron beam that can be used in some embodiments of the present invention.

FIG. 37B shows a perspective view of the target and the scattered electron beam of FIG. 37A.

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

FIG. 2 illustrates a side view of a target having a microstructure that has been bombarded with a dispersed electron beam, which may be used in some embodiments of the present invention.

FIG. 38B shows a perspective view of the target and the scattered electron beam of FIG. 38A.

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

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

3 shows cross sections of a plurality of targets having microstructures of the X-ray generating material in various arrangements. Here, multiple 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 microstructure 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 microstructure 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 shows a prior art embodiment of a plurality of X-ray lenses having two cylindrical optical elements .

1 shows a prior art embodiment of a plurality of X-ray lenses having a plurality of cylindrical optical elements.

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

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

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 acts as a cathode, and in many cases, generates a beam of electrons 111 by applying a current to the filament. Let it. Any number of prior art techniques for electron beam generation may be used in the multiple embodiments of the invention disclosed herein. Additional known techniques used for electron beam generation include heating for thermionic emission, Schottky emission (combination of heating and field emission), multiple emitters with nanostructures such as carbon nanotubes, multiple ferroelectrics Including 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, No. 18re, No. 182b, pp. 182b). Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophonics (ISRN Nanomaterials, 2014 Edition, Publication No. 879827, p. 23, 2014). See Riege, "Electron Emission from Ferroelectrics-A Review" (CERN Report CERN AT / 93-18, Geneva, Switzerland, July 1993).

As described above, the target 1100 having the target substrate 1000 and the region 700 of X-ray generating material is electrically connected to the opposite high voltage conductor 22 and the target support 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. Impact of the electrons 111 on the target 1100 causes a number of effects, including 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 another system for the lens. Accordingly, 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. Otherwise it can be oriented.

As illustrated in FIG. 7, the arrangement of the microstructures 700 is such that the impact of the electron beam or the beam 111 on the plurality of microstructures 700 is such that the intensity in the direction of the field of view is perpendicular to the surface normal of the target. Can be arranged to cause release in such a way as to increase or accumulate. The direction may also be selected by an opening 840 in the screen 84 of the system to form a directional beam 888 exiting the system through the window 40. In some embodiments, opening 840 may be located outside the vacuum chamber, or more generally, window 40 itself may serve as opening 840 . 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 invention disclosed herein, is a co-pending U.S. patent application entitled "STRUCTURED TARGETS FOR X-RAY GENERATION". (US Patent Application No. 14 / 465,816, filed August 21, 2014), the contents of which are hereby incorporated by reference in their entirety and are included as Appendix A. Any of the target designs and configurations disclosed in the above referenced co-pending application may be considered for use as a component of any or all of the X-ray sources disclosed herein.

FIG. 8 illustrates a target 1100 as may be used in some embodiments of the present invention. In this drawing, a substrate 1000 has a region 1001 having an arrangement of microstructures 700 including an X-ray generating material (typically, a metal material) arranged in a regular arrangement of right square pillars. In a vacuum, the electrons 111 bombard the target from above, generating heat and X-rays in the microstructure 700. The material of the substrate 1000 should be such that it 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), and the microstructure is 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 the heat generated in the microstructure 700 is effectively dissipated to the substrate 1000. It is preferable that they make close contact. However, targets used in other embodiments may have fewer direct contact surfaces. Generally, when the term "embedding" is used in the present 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 may be mounted as an alternative to the target 01 for the transmitted x-ray source 08 illustrated in FIG. 1 or the target 100 illustrated for the reflected x-ray source 80 in FIG. It may be adapted for use as a target 500 used with a rotating anode X-ray source 580.

  It should be noted here that the word “microstructure” as used herein specifically refers to a microstructure having 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" refer to materials such as substrates that are not selected due to their x-ray generating properties. Can be used for these structures as they are formed. The word "microstructure" is reserved for structures having a material selected for their x-ray generating properties.

  Similarly, the word "microstructure" is used, but X-ray generating structures having dimensions less than 1 micron or even smaller at the nanoscale (i.e., greater than 10 nm) are also referred to as "microstructures" as used herein. It should be noted that it can be described by the word "microstructure".

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

FIG. 10 illustrates another target 1100-E as may be used in some embodiments of the present invention, where the target 1100-E emits X-rays when exposed to the electrons 111. It still has a region 1001-E with an array of microstructures 700-E containing X-ray material, but the region 1001-E is arranged flush with the edge of the substrate 1000-E, Or it is arranged near it. This configuration can be useful in targets where emission at angles near 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.

  However, a 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 when compared to FIG. Thus, heat is not removed symmetrically from the microstructure, increasing local heating and may worsen heat flow.

  To address this problem, some targets, such as those used in some embodiments of the present invention, may employ a configuration as shown in FIG. Here, the target 1100-R has a substrate 1000-R having a shelf-shaped recess 1002-R. Thus, the region 1001-R having the arrangement of the microstructures 700-R is disposed flush with or near the concave edge 1003-R of the substrate, and is located at 0 ° or 0 °. It is possible to emit X-rays at an angle close to ° without being reabsorbed by the substrate 1000-R, but still more symmetrical 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 representative electrons bombarding the two microstructures 700 shown, one representative electron interacting with the substrate.

As discussed in Equation 1 above, the depth of penetration can be estimated by Pot's law. Using this formula, 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 an R on the left 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 is about 3.5 microns.

  Most of the characteristic X-rays (K-rays) of Cu occur within the depth D. Electron interaction below that depth typically produces little characteristic X-rays (K-rays) but contributes to heat generation, thereby creating a gradual temperature gradient along the depth. Bring. Thus, in some embodiments, it is preferable to set the maximum thickness of the microstructure in the target to limit electron interactions in the material and optimize local temperature gradients. 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 incident electron energy. In this case, the lower mass density of the substrate results in a lower energy deposition rate on the substrate material immediately below the X-ray generating material, which in turn results in a lower temperature of the underlying substrate material. This results in a larger temperature gradient between the X-ray generating material and the substrate, increasing heat transfer. The temperature gradient is further magnified by the high thermal conductivity of the substrate material.

  For the same reason, selecting a depth D that is shallower than the electron penetration depth is also generally preferred for efficient generation of bremsstrahlung radiation. This is because electrons below its depth have lower energy and therefore lower x-ray generation efficiency.

  Note: Other options for the dimensions of the X-ray generating material may be used. For targets such as those used in some embodiments of the present invention, the depth of the X-ray material may be selected to be 50% of the electron penetration depth. In another embodiment, the depth of the X-ray material may 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 may be specified depending on the desired x-ray spectrum and properties of the selected x-ray material.

  Note: In other targets, such as may be used in some embodiments of the present invention, a particular ratio between the depth of the x-ray generating material and the lateral dimensions (such as width W and length L) may also be specified. . For example, if the depth is selected to be a particular magnitude D, then the lateral dimensions W and / or L are selected to be less than or equal to 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 less than or equal to twice D. The depth D and the lateral dimensions W and L (width and length of the X-ray generating microstructure) can be defined with respect to the axis of electron propagation or with respect to the orientation of the surface of the X-ray generating material. This should also be noted. For normally incident electrons, they have the same dimensions. Care must be taken for obliquely incident electrons to ensure that proper predictions are used.

FIG. 13 shows the relative X-ray generation from the various regions shown in FIG. The 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 are generated, and regions 1280 and 1080 where electrons interact with the substrate are Generate characteristic X-rays (not characteristic X-rays of elements in the X-ray generation regions 248 of the plurality of microstructures 700 ). Further, bremsstrahlung X-rays emitted from regions 248 of the plurality of microstructures 700 of the X-ray generating material typically have those regions in regions 1280 and 1080 where electrons only encounter low atomic number substrates. Are much more intense than the weak continuous X-rays 1088 and 1228 emitted.

  The illustration in FIG. 13 shows X-rays emitted only to the right, which are located to the right when this target is used in the low angle high intensity configurations discussed in FIGS. 5A-5C. It should be noted that the expected window or collector is expected. X-rays are practically typically emitted from these areas in all directions.

  As FIG. 13 shows an arrangement that allows for a linear accumulation of characteristic X-rays along the microstructure, and thus can generate a relatively strong characteristic X-ray signal, a plurality of materials can be used for 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, which effectively acts as an X-ray filter. Other alternatives for materials and geometric parameters may be non-characteristics, such as in applications where bandpass of low energy X-rays is desired (eg, for image processing or fluorescence analysis of low atomic number materials). May be selected if desired (eg, in a non-linear fashion).

  So far, targets arranged in a planar structure have been shown. These are generally easier to implement. Apparatus and process recipes for deposition, etching, and other steps of the planar process are useful for processing devices for micro-electro-mechanical systems (MEMS) applications using planar diamond, and for silicon wafers for the semiconductor industry. Because it is well known in processing.

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

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 0 ° take-off angles. Thus, any increase in brightness realized by looking 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. Thus, an arrangement may be desired that has a selected distance in relation to the x-ray attenuation length, such that the emitted x-rays do not pass through as much additional material as possible.

An illustration of some of the targets that may be used in some embodiments of the present invention is shown in FIG. In FIG. 14, an X-ray generating area having a single microstructure 2700 is configured at or near a concave edge 2003 of the substrate in contact with the ledge 2002, similar to the situation illustrated in FIG. are doing. The X-ray generating microstructure 2700 has the shape of a rectangular bar having a width W, a length L, and a depth or thickness D embedded in the substrate 2000. Emit line 2888.

  Bar thickness D (thickness along the surface normal of the target) should be between 1/3 and 2/3 of the electron penetration depth of the X-ray generating material at incident electron energy for optimal thermal performance. Is selected. The thickness D of the bar can also be selected to obtain a desired X-ray source size in the vertical direction. The bar width W 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.

  The length L of the bar as illustrated is approximately four times D, but can be any size, typically 1 / X 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 properties, relative thermal properties, and electron Depending on the amount of heat that is expected to be generated when an impact is applied, an arbitrary value may be selected from the point (p = 0) coplanar with the edge portion 2003 to a maximum of 1 mm.

Some portion of an exemplary alternative targets such as may be used in embodiments of the present invention is shown in Figure 15. In this target, an X-ray generation region having six microstructures 2701, 2702, 2703, 2704, 2705, 2706 is formed at or near a concave edge 2003 of a target substrate 2000 in contact with a shelf 2002. This is similar to the situation illustrated in FIGS. As shown, the X-ray generating 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 impacted by electrons 111. Emits X-rays 2888-D when pressed.

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 example of FIG. Similarly, in the case shown in FIG. 14, the thickness D (the thickness along the surface normal of the target) of the microstructure 2701-2706 is determined by the X-ray generation 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. Similarly, 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 as illustrated, W is approximately 1 of D 0.5 times. As discussed previously, the bar width W can be substantially smaller or larger depending on the size of the source spot desired.

However, as shown, a single bar 2700 of length L as illustrated in FIG. 14 has been replaced by microstructures 2701, 2702, 2703, 2704, 2705, 2706 in the form of six sub- bars. , And each length l is L / 6. The volume of X-ray generation (when impacted at the same electron density) is the same, where each subbar has five surfaces that transfer heat to the substrate, and the X-ray generation subbars 2701-2706 Increases heat dissipation to the substrate. As illustrated, the separation distance d between the plurality of sub-bars is approximately equal to l, but larger or smaller dimensions may be used, depending on the X-ray dose absorbed by the substrate and the X-ray It depends on the relative temperature gradient that can be achieved between the particular material of the generating microstructures 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 and relative thermal properties of the substrate material Depending on the amount of heat that is expected to be generated when subjected to an impact with electrons, an arbitrary value may be selected from a point (p = 0) coplanar with the edge portion 2003 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 linear attenuation length of X-rays in the X-ray generation material, but is more than half to three times the distance. Can be selected up to. 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 / It was chosen to be equal to 3, but could be substantially larger. The thickness D of the bar can also be selected to obtain a desired X-ray source size approximately equal in the 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.

  FIGS. 16A-16C have an array of rectangular prism-shaped microstructures 700 including x-ray generating materials arranged in a regular array, as may be used in some embodiments of the present invention. A target area 1001 is shown. FIG. 16A shows a perspective view of 16 microstructures 700 for this target, FIG. 16B shows a top view of the same area, and FIG. 16C shows a side / cross-sectional view of the same area. (For the term "side view / section view" of the present disclosure, a meaning figure is a view of creating a section of an object and then looking from the side to the surface of the section. It shows both the details of the cross-section and, assuming that the substrate itself is transparent (in the case of diamond, generally applies to visible light), further inside the material that can be seen from the side).

In the targets of FIGS. 16A-16C , the plurality of microstructures are fabricated such that five of the six surfaces are in intimate thermal contact with the substrate. As illustrated, the top surface of the plurality of microstructures 700 is flush with the surface of the substrate, but other targets having the plurality of microstructures in the recesses may be manufactured, 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, increasing the surface area, decreasing the thickness, and increasing ΔT all lead to a proportional increase in heat transfer.

Alternative targets, 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 make 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 plane of the substrate, as shown in FIG. The ratio of the total surface area in contact with the substrate to the deposited microstructure is given by:
If the value of D relative to W and L is small, the ratio will be substantially one. The ratio increases as the thickness increases, and the ratio is 5 for a cube (D = W = L) where five equal faces make thermal contact. If a cap layer of material having similar properties to the substrate in terms of mass density and thermal conductivity is used, the ratio can increase to 6.

Heat conduction is illustrated by representative arrows in FIG. 17, in which heat generated by the plurality of microstructures 700 embedded in the substrate 1000 passes through the plurality of microstructures 700 through the bottom surface and the plurality of side surfaces. (The arrows transmitting through the sides out of the plane of the drawing are not shown). The amount of heat transferred per unit time (ΔQ) transmitted through a material having an area A and a 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, increasing the surface area, decreasing the thickness, and increasing ΔT all lead to a proportional increase in heat transfer.

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

An illustration of another target area 2001, such as may be used in some embodiments of the present invention, is shown in FIGS. 4 shows a region 2001 of a target according to an embodiment of the present invention, having an arrangement of The arrangement shown is a modified checkerboard of square prisms, but other configurations and arrangements of multiple microstructures may be used.

  The same applies to the 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 height of the steps may be selected to be between one and three times the thickness of the plurality of microstructures. The overall height of all steps may be selected to be equal to or less than the desired X-ray source size along the vertical (thickness direction).

  The overall width of the microstructure region may be equal to the desired X-ray source size in the corresponding direction. The overall appearance resembles the steps of an X-ray source. FIG. 19A shows a perspective view of the 18 buried microstructures 2790 and 2791, FIG. 19B shows a top view of the same region, and FIG. 19C shows a side / cross-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 top of the step structure.

  FIG. 20 shows the X-ray emission 2888-S from the stepped target of FIG. 19C when impacted by the electrons 111. The same applies to the targets used in the other embodiments, but the 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 in thermal contact with the substrate 2000, the conduction of heat out of the X-ray material is such that the X-ray material Still larger than the deposited configuration. However, for one surface, the x-ray emission is not attenuated by absorption by other adjacent prisms, but is negligibly attenuated by adjacent substrate materials.

  Thus, the brightness of the X-rays from each prism was compared to the X-ray emission from the targets of FIGS. 18A-18C, which also show 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 Attenuated by both prisms and substrate material in adjacent rows.

  One such embodiment with a target with topography involves first providing a substrate with topography and then embedding a plurality of prisms of x-ray material according to the manufacturing process for planar substrates described above. Can be manufactured by Alternatively, the first steps of forming the cavities filled with the X-ray material can be enhanced to form a step-like topographic structure in the initial flat substrate. In either case, if it is desired to overlay the embedded prism with a particular feature topography, additional multiple alignment steps are used, such as are known to those skilled in the planar process. obtain.

  The plurality of microstructures may be embedded at a distance to the edge of the stairs as illustrated in FIGS. 19A-19C and 20, or may be embedded in the edge (as shown in FIG. 10). It can be embedded flush. Determining which configuration is appropriate for a particular application may depend on the exact properties of the x-ray generating material and the substrate material, so that, for example, heat transfer through five or four surfaces The additional brightness realized by the increase in electron current enabled by can be compared to the additional brightness realized by free space emission or reabsorption through a portion 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 create multiple prisms in multiple layers, are considered relative to the achievable increase in brightness May be necessary.

  As described in the above-cited U.S. Patent Application No. 14 / 465,816, other target configurations that may be used in embodiments of the present invention include multiple microstructures having multiple X-ray generating materials. , A plurality of microstructures having an alloy of an X-ray generating material, a plurality of microstructures having a diffusion preventing layer or an adhesion layer deposited thereon, a plurality of microstructures having a thermally 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 the above-cited U.S. Patent Application No. 14 / 465,816, other target configurations that may be used in embodiments of the present invention include micronized substrates on thermally conductive substrates such as diamond or sapphire. Multiple microscopic features that can have any number of conventional x-ray target materials (such as copper (Cu), molybdenum (Mo), and tungsten (W)) that are patterned (or embedded therein) as features of a scale dimension An array of structures. In some embodiments, the plurality of microstructures have alternatively been limited in their 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 the above-cited U.S. Patent Application No. 14 / 465,816, other target configurations that may be used in embodiments of the present invention include cubes, rectangular blocks, regular prisms, square prisms, Trapezoidal columns, spheres, ovals, barrels, cylinders, triangular prisms, pyramids, tetrahedrons, or surface textures or structures that increase the surface area to generate the most intense X-rays and distribute heat efficiently An array of multiple microstructures that take any number of geometric shapes, such as other specially designed shapes, including shapes with

  As described in the above-cited U.S. Patent Application No. 14 / 465,816, 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 multiple microstructures with various materials as X-ray generating materials, including these combinations and their alloys.

  The embodiments described above provide various X-ray target configurations with multiple microstructures having X-ray material 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 being bombarded with electrons to emit X-rays, they have been used as stationary X-ray targets in another conventional source and have been used as targets 01 in the transmitted X-ray source 08 of FIG. Alternatively, one of the targets 100 of the reflective X-ray source 80 of FIG. 2 may be replaced with a microstructured target forming an X-ray source according to embodiments of the present invention.

  The targets described above may be embedded in a movable X-ray target to form, for example, the target 500 of the rotating anode X-ray source 80 of FIG. 6A with a movable microstructure target according to other embodiments of the present invention. For example, 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 into 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. X-rays tend to be emitted isotropically, but this analysis is for a view along an axis passing through the center of the linear array of sub-sources, where the screen 84 with the aperture 840 is placed. ing.

  As depicted in FIG. 21, the aperture allows the accumulated 0 ° X-rays to emerge from the source, but in practice, +/− 3 ° or to the surface normal. It should be noted that apertures that allow multiple angles of emitted x-rays that are also emitted at +/− 6 ° may 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, the emission for the rightmost emitter will simply go right through free space, as illustrated. Propagate. However, x-rays from other emitters are attenuated through absorption, scattering, or other loss mechanisms that occur during the passage of any material between the emitters. It is also attenuated by divergence from the propagation axis and losses caused by passing through adjacent emitters.

When defined as follows: I _i : X-ray emission intensity 8i8 from the i-th emitter 80i, 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 on-axis X-rays to the right from an array of N emitters is expressed as:
This ultimately becomes:

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

Further, if the emitters are arranged in a regular array with substantially the same value for transmission between the 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 also the same, then:
Next, the total emission intensity becomes:

Note that T _i and T _{i, i−1} represent the attenuation of the propagation due to the loss and therefore always have a value between 0 and 1. If N is large, the sum on the right side can be approximated by a geometric series, and is given by:
Thus, the approximate strength is expressed by the following equation.
This equation suggests that I _tot increases by making the product of the transmittance 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 arranged in a row before the loss and attenuation wastes adding another X-ray emitting element. For example, if the width of the emitting element is 1 / e of the X-ray attenuation length, the transmittance of the element will be 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 equation suggests that a large number of elements having a width equal to the length of 1 / e can only increase the strength by 1.564 times, and that even if the number of elements is increased, two elements It suggests that it is less axial and less productive.

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

It should be noted that x-ray attenuation is different for x-rays of different energies 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 decay length of three types of X-ray generating materials, that is, molybdenum (Mo), copper (Cu), and tungsten (W), for X-rays having energies ranging from 1 keV to 1000 keV, and three types of substrates. It shows the 1 / e decay length of materials (ie, graphite (C), beryllium (Be), and water (H ₂ O) for X-rays having energies ranging from 10 keV to 400 keV. [Data shown here were originally from B.C. L. Henke, E .; M. Gullikson, J.M. C. According to Davis, "X-ray interactions: photoabsorption, scattering, transmission, and reflection at E = 50-30000 eV, Z = 1-92", Atomic Data and 2nd ed. has been published (July 1993), <http: // henke. lbl. gov / optical_constants / atten2. html>. Other X-ray absorption tables can be found at <http: // physics. nest. gov / PhysRefData / XrayMassCoef / chap2. html>].

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

As an example of using a value of 22, the X-ray of 60keV in tungsten, _{L 1 / e} of approximately 200 microns, and the transmittance of the X-ray generating elements 20 microns wide, it 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: become.
Thus, for a periodic array of 20 micron wide tungsten elements embedded in a beryllium substrate and spaced 100 microns apart, the best estimate of the on-axis intensity is:
This represents an order of magnitude increase in X-ray intensity when compared to a single tungsten X-ray emitting element.

3. Control of the X-ray Source There are several 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 for control and adjustment of some or all of these variables, or may not control or adjust any of these variables.

3.1. Variations of Electron Beam First, in some embodiments, the beam or beams, such as electrons 111 or 1111, 1112, 1113, that impact X-ray generating elements 801, 802, 803,. It may 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 may be located within the vacuum environment of the x-ray source, and multiple magnetic field focusing elements may be located outside the vacuum. It is disclosed in prior art REBL (Reflective Electron Beam Lithography System) as described in US Pat. No. 6,870,172, “Maskless reflection electron beam projection lithography”. Various other electronic imaging 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 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 the electron beams 1131, 1132, 1133, etc. (such as convergent electron beams) are at multiple angles, as illustrated in FIG. 23C, as illustrated in FIG. 23D. The electron beams 1141, 1142, 1143, etc. have an angle θ from both sides, and the electron beams 1151, 1152, 1153, etc. each have various intensities or electron densities as illustrated in FIG. Multiple elements may be required with a uniform large area electron beam 111 as described, or in any combination of many electron beam configurations that may be devised by those skilled in the art. May shock 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 area between the plurality of x-ray generating elements. If the X-ray generating material is very absorptive, as illustrated in FIG. 23E, the region that must emit X-rays and travel the longest distance through several other X-ray generating elements Larger electron densities can be used to bombard. Similarly, if the depth of electron penetration is deep, as illustrated in FIG. 23B, the X-ray generating 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 X-ray generating elements may be filled with a solid material that facilitates dissipating heat from the X-ray generating elements rather than a vacuum. Such a source target having an array of multiple X-ray generating elements embedded or embedded in a thermally conductive substrate such as diamond is disclosed in co-pending US patent application Ser. No. 14 / 465,816 as described above. , Which is incorporated by reference in its entirety.

  If the region between the plurality of X-ray generating elements has a solid material and is bombarded with electrons, the region will tend to be heated under electron irradiation, whereby the X-ray generating elements and , The heat flow from the X-ray generating element is reduced. The limitation on the amount of electron energy and density is 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, which means that It is generally preferred to increase heat dissipation, which may be achieved in part by reducing electron irradiation in the non-X-ray producing region. Since the heat generated by electron irradiation tends to increase as atomic number Z increases, it is necessary to select a substrate having a low atomic number material such as beryllium (atomic number 4) or diamond (atomic number 6). It should be noted that it may be preferred.

A source having multiple electron beams used to independently bombard separate multiple X-ray generating elements may also be configured to allow different accelerating voltages to be used with different electron beam sources. . Such a source 80-B is illustrated in FIG. Also in this example, the former high voltage source 10 is connected via a conductor 21-A to an electron emitter 11-A which emits electrons 111-A toward a target 1100-B. However, two additional "boosters" for the voltages 10-B and 10-C are also provided, and these high potentials are transmitted via lines 21-B and 21-C to electrons 111-B and 111-111 of different energies. -C are connected to additional electron emitters 11-B and 11-C, respectively. A 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, ... it can be used to impact the like.

  This may provide a number of advantages in managing X-ray emission in that electrons of different energies may generate different X-ray emission spectra, depending on the material used for the individual X-ray generating elements. The resulting heat load can also be managed through the use of different electronic energies. For such multiple beam configurations, the design of multiple electron lenses to keep the various beams from interfering with each other and to provide the 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 structural unit, and to consider multiple intervening regions to be the same, but some embodiments have variations in these parameters. There can be several advantages to that.

In some embodiments, the different X-ray generating elements may have different X-ray emitting materials, such that the on-axis view shows characteristic X-rays of different spectra from different materials. A relatively transparent material to X-rays, a position closest to the output window 840 (e.g., the rightmost element 801 in FIG. 21) but may be used in, material which absorbs more strongly, the other of the plurality of 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.

  In some embodiments, the distance between the plurality of X-ray generating elements can be varied depending on the expected thermal load of the different materials. For example, a wider spacing between multiple elements may be used for elements where more heat is expected to be generated under electron bombardment, and where less heat is expected, a smaller spacing may be used. 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,... May have various sizes and geometric shapes. This may be particularly useful in situations where a plurality of different materials are used and the different materials have different electron deceleration processes and X-ray absorption.

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 decay length of X-rays in the material and the "continuous deceleration approximation" of electrons (CSDA) This is the ratio to half the range. Since the electrons can lose energy due to multiple collisions as they slow down, the CSDA range of the electrons is typically greater than the penetration depth. 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 the previously cited source by Henke et al., And CSDA range data is from NIST's "Physical Measurement Laboratory"<http: // physics. nest. gov / PhysRefData / Star / Text / ESTAR. html>. The ratio, when used for linear accumulation of X-rays, may be considered a figure of merit for 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 X-rays appear to be emitted from a shallower depth spot).

FIG. 27 shows a plot 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.

  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. With some choices of target materials, the material of the thin foil coating may be sufficient to provide the required X-ray emission, and more complex embedding or embedding microstructures may not be required.

3.4. Time-Division X-Ray Generation In other embodiments, the X-ray generating elements 801, 802, 803, 804,... 1214,... Can be switched on and off over time to spread the thermal load. This can be particularly effective when viewed on-axis. This is because all X-rays appear to be from the same source.

  One embodiment of time sharing is illustrated in FIGS. 28A-28C. In FIG. 28A, at the first time step t = 0, the electron beams 1211 and 1214 for elements 801 and 804 are on, respectively, and all others are 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, electron beams 1213 and 1216 for elements 803 and 806 are on and all others are off. The system may simply hide the various electron beams between these configurations, or block them with a mechanical shutter, or change the position of these electron beams. Can be switched.

Further, in some embodiments, the electron beam may simply scan over the target with the x-ray generating material. In some embodiments, this scan may be a regular raster scan; in other embodiments, the scan may be "dwelling" or scan the x-ray generation area at a slower rate. On the other hand, the scanning may be non-uniform, such as rapid movement from one X-ray generation area to the next X-ray generation area. 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 Thus, it can be designed to form a "pulsed" X-ray source . This may have some advantages for some specific applications.

  Sources that can change the timing of electron irradiation use a plurality of different types of embedded microstructures that are impacted with a plurality of different potential electrons to emit various spectra of X-ray energy, as described above. It may also be particularly useful for multiple embodiments.

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

  FIG. 29A illustrates X-ray emission through an off-axis window 841 or an opening in the screen 84 or wall. Since X-ray emission is generally isotropic, emission from all electron-impacted microstructures is also emitted in this direction. However, the various rays of this emission 878 passing through the aperture 841 are not propagating in the same direction but are dispersed, giving the appearance of an expanded source. However, if an extended source aspect is desired, a small angle assembly configuration for x-rays using such off-axis may be appropriate.

FIG. 29B shows emission from a plurality of microstructures this time in a direction 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 for these sizes, so that off- axis angles at which X-rays can propagate without attenuation by a plurality of 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 (showing the target in more detail) are more general X-ray systems 80 that incorporate some of the elements described above. -C. The system includes a plurality of electron emitters 11-A, 11-A that generate electron beams 111-A, 111-B, 111-C via a plurality of conductors 21-A, 21-B, and 21-C. B, and an electronic system controller 10-V that sends various voltages to 11-C. 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-C via conductive wires 27-A, 27-B, and 27-C. -C to 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 Moved through the cooling path 1200.

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

FIG. 31 shows a portion of a target 1100-C under electron bombardment in an enlarged view of the present system, into which two additional electron beams 111-D and 111-E have been added. I have. As illustrated, both beams 111-D and 111-E have a higher current than the three electron beams 111-A, 111-B, and 111-C on the right, and the leftmost electron beam 111-C. -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 receiving the higher current are between these and the rightmost elements 801, 802 and 803 receiving the lower electron current. It is also illustrated to have a spacing greater than the spacing provided in. In some embodiments, 804 and 805 can be comprised of a material having a higher atomic number than 801, 802, and 803.

FIG. 31 also shows a conductive overcoat film 770 having both thermal conductivity (for removing heat) and conductivity, and a return path for electrons to the ground 722 is provided. Also shown is a screen 84 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 a target substrate having a plurality of microstructures of an X-ray generating material, the transmittance T of X-rays to the substrate is preferably substantially 1. The substrate material of the length L and the linear absorption coefficient alpha _s, expressed as follows.
Here, L _{1 / e} is a length at which the X-ray intensity decreases to 1 / e times.

Generally, it is expressed by the following equation.
Here, X is X-ray energy (keV), and Z is an atomic number. Thus, to increase L _{1 / e} (ie, to make the material more transparent), higher X-ray energies are required, and lower atomic numbers are highly preferred. Thus, both beryllium (atomic number 4) and carbon (atomic number 6) in various forms (eg, diamond, graphite, etc.) may be desirable as substrates. For 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 Multiple Embodiments of the Invention 4.1.2 Two-Side Target One embodiment of a source 80-D using a target having a plurality of X-ray generating elements arranged for line accumulation is described below. 32, the target 2200 is shown in more detail in FIG.

  In the embodiment shown in FIG. 32, the 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 the target 2200. . The characteristics of the electron beams 1221 and 1222, such as the position, direction, and focusing, are adjusted via a plurality of electron lenses 70-D that adjust the beam characteristics with beam current settings and high voltage settings via 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 the X-rays 821 and 822 generated from the respective positions emit a beam of X-rays 2888 from the source 80-D. The thin coatings 2221 and 2222 on both sides of the target 2200 are impacted in such a position as to be aligned with the openings 840 in the screen 84 that allow for

  Multiple electron lenses 70-D and 70-E combine with electron beams 1221 and 1222 because large area bombardment by electrons provides greater overlap, but higher electron density results in higher x-ray emission. To a small spot of 25 microns or even smaller. For such a small spot in the configuration as shown, the position of the two electron impact spots to generate a superimposed X-ray emission pattern (and thus to achieve a linear accumulation of the two spots) Alignment is performed by placing an x-ray detector beyond the aperture 840 and measuring the intensity of the x-ray beam 2888 so that 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 greatest at the detector.

  Target 2200 may be securely attached to a structure in the vacuum chamber, or may be repositioned. In some embodiments, the target may be mounted as a rotating anode to further dissipate heat.

  As described above, the thickness of the coatings 2221 and 2222 may be selected based on the expected electron energy and penetration depth or CSDA estimates of the material. If the impact occurs obliquely to the surface normal, as illustrated, the angle of incidence can also influence the choice of coating thickness. Although the tilt of the target 2200 with respect to the 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-sided 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 of the 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 includes a lead 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 target 500-R, coated on both sides with coatings 2521 and 2522 having an x-ray generating material that produces x-rays 2588. It should also be clear that embodiments can be designed with additional controls, such as multiple electron lenses to steer the beam or apertures to define the x-ray beam output.

4.2. Multiple Two-Side Targets The source 80-D as described above is not limited to a single target with two faces. Shown in FIG. 35 are 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, controlled this time to impact multiple coatings on each of the two targets 2203, 2204, and to generate X-rays 831 and 832, and 841 and 842, respectively. The source has a configuration similar to that illustrated in FIG. 32, except that there are 1232, 1241, 1242.

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

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

  As described above, the thickness of the coatings 2231, 2232 and 2241, 2242 may be selected based on the expected electron energy and penetration depth or CSDA estimate of the material. If the impact occurs obliquely to the surface normal, as illustrated, the angle of incidence can also influence the choice of coating thickness. The tilt of the targets 2203 and 2204 with respect 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, embodiments with any number of targets having multiple surfaces coated with x-ray generating material have the same Used in a manner, each target can be bombarded on one or both sides with an independently controlled electron beam. Further, the coatings for the 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 have a 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. Further, by adjusting the various electron beam currents and densities, a tunable mix of X-rays can be achieved.

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

4.3. FIG. 36 illustrates another embodiment where multiple targets are replaced with a microstructure of X-ray generating material embedded in the substrate instead of a thin coating. Have.

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

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

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

  Modifications of this embodiment are illustrated in FIGS. 38A to 38C. In the target 2401 of this embodiment, instead of a coating, microstructures 2481, 2482, 2483 of X-ray generating material are embedded in a substrate 2410. The scattered electron beam 2411 impacts these microstructures, producing 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, when viewed from a particular angle, cause They are simply aligned so that they appear to be overlapping, and thus merely appear to be a single, brighter x-ray source.

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

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

Generally, 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. As previously described, the 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 to the 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 measure of the spectral power, which can then be used to instruct the electron beam to generate a particular characteristic line to increase or decrease its power.

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

It should be noted that the emission originates isotropically from all targets, and that multiple X-ray lenses collecting and focusing affect X-rays propagating in both directions. Thus, a detector located at the opposite end of the chain of targets may serve as a calibration of the x-ray system and a monitoring of the overall output.

5.1. General Reflective Lens FIG. 39 shows 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 provided. Each of the plurality of targets is impacted by an electron beam 1181, 1182, 1183, respectively, to generate X-rays 2818, 2828, 2838 respectively.

  An X-ray imaging mirror lens 2821, 2822, 2831, 2832 is disposed between each of the plurality of X-ray emission targets to collect X-rays emitted at a plurality of wider angles and separate them into another X-ray. The target is redirected to a focal point at a position corresponding to the X-ray generation spot. As illustrated, the focal point is set to be the X-ray generation spot of the adjacent target, but in some embodiments, all X-ray mirrors place the X-ray at the same point, for example, 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 may be elliptical mirrors with reflective surfaces, typically made of glass, or surfaces coated with high mass density materials, or multi-layer coated X-ray reflectors ( (Typically made using layers of molybdenum (Mo) and silicon (Si)), or a crystal lens, or a combination thereof, may be any conventional x-ray imaging optical element. The choice of materials and structures for the x-ray lens and its coating can vary depending on the spectrum of x-rays that are collected and refocused. Although illustrated as a cross section, the entire X-ray lens or a portion thereof can have cylindrical symmetry.

  A modified example of this embodiment is illustrated in FIG. In this embodiment, the first (upstream) X-ray target 2830 here comprises a substrate 2833 with a plurality of microstructures 2883 of X-ray generating material embedded therein, as described elsewhere. I have. The intensity of the X-rays 2838-A emitted from this target 2830 increases due to the linear accumulation of the X-rays emitted from the plurality of microstructures 2883, and in the embodiments described previously. 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 angle of incidence, size, shape, (as illustrated) than the embodiment of FIG. 39, to more effectively impact the plurality of microstructures 2883. And can be adjusted to have focus.

  Another variation of this embodiment is illustrated in FIG. In this example, 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 of X-ray beam characteristics such as brightness, brightness, total intensity, flux, energy spectrum, beam profile, and divergence or convergence.

5.2. Walter Lenses and Other Multi-Element X-Ray Lenses Another embodiment of the present invention is illustrated in FIG. In this embodiment, the optical elements 2921 and 2931 that collect the X-rays emitted from one target and focus it downstream are the optical elements now known as Walter lenses. A Walta lens is a well-known system of nested mirrors that collects and focuses X-rays, typically using a parabolic and / or hyperbolic reflecting surface, each of which is typically used at a grazing angle. 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).

FIGS. 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 the X-ray emitted from one target and focus it downstream are the 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 another end of the desired location. However, unlike fiber optics, which have 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 grazing angles. You.

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

5.4. Variations particular option, reflecting lens, Worutarenzu, or it has 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 in FIG. Although multiple targets having multiple microstructures are used in these examples, multiple targets having multiple thin films, such as those illustrated in FIGS. 33 and 35, may be used with these X-ray lenses to focus It should also be noted that it can be used.

6. Limitations and Extensions This application discloses several embodiments of the present invention, including the best mode contemplated by the inventors. Although particular embodiments may be shown, it will be appreciated that elements discussed in detail only for some embodiments may also apply to other embodiments. .

  Although specific materials, designs, configurations, and manufacturing steps have been presented to illustrate the 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 it is intended that the present invention be limited only by the scope of the appended claims.

  Preferably, all elements, components, and steps described herein are included. It is understood that any of these elements, members, steps may be replaced by other elements, members, steps, or omitted altogether, as will be apparent to those skilled in the art. Should be.

  In general, this document discloses at least the following: A small source for generating high-brightness X-rays. Higher brightness is achieved by electron beam bombardment of multiple regions aligned with one another to achieve linear accumulation of X-rays. This is a novel technique with multiple microstructures of x-ray generating material made by aligning discrete x-ray emitters or in intimate thermal contact with high thermal conductivity substrates. This is achieved by using an X-ray target. This allows heat to be more efficiently dissipated 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 an on-axis convergence angle and allows the accumulation of X-rays from multiple aligned microstructures, so as to have a single source. Visible, this is also known as “0 °” x-ray emission.

This document also demonstrates at least the following concepts:
(Concept 1)
A vacuum chamber;
An X-ray transparent window mounted on 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 properties;
The 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 a 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 a surface of the substrate;
X-ray source according to 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)
Further comprising means for directing an electron beam emitted from the emitter onto the target;
An X-ray source according to any one of concepts 1 to 3.
(Concept 5)
The means for directing an electron beam comprises a plurality of electron lenses;
X-ray source according to concept 4.
(Concept 6)
The means for directing an electron beam comprises a plurality of electrostatic lenses;
X-ray source according to concept 4 or 5.
(Concept 7)
The means for directing an electron beam comprises a plurality of magnetic lenses;
X-ray source according to any one of concepts 4 to 6.
(Concept 8)
The means for directing an electron beam includes: focusing, diverging, defocusing, scanning, raster scanning, pausing, invisible, sweeping, changing beam direction, beam Enabling control of the electron beam by an operation selected from the group consisting of changing the intensity profile, forming a plurality of 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 an electron beam enables the electron beam to be focused to a spot size of less than 30 microns in at least one dimension;
An X-ray source according to any one of concepts 4 to 8.
(Concept 10)
The means for directing an electron beam enables the electron beam to be directed to a pattern corresponding to a position of at least a portion of the plurality of discrete structures;
X-ray source according to any one of concepts 1 to 9.
(Concept 11)
Said means for directing an electron beam, wherein said means for directing said electron beam to a pattern corresponding to the position of at least a part of said plurality of discrete structures;
The pattern is adapted in time in response to a signal from a detector that monitors a plurality of predetermined properties of the emitted x-rays;
X-ray source according to concept 10.
(Concept 12)
The predetermined plurality of properties of the emitted X-rays 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;
X-ray source according to any one of concepts 1 to 12.
(Concept 14)
The plurality of discrete structures are manufactured to have a similar shape,
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 column, a pyramid, a tetrahedron, a column, a sphere, an oval, and a barrel.
X-ray source according to concept 14.
(Concept 16)
The first selected material is selected from the group consisting of beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon;
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.
X-ray source according to any one of concepts 1 to 16.
(Concept 18)
A subset of the plurality of discrete structures having a third material selected for its x-ray generation properties;
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.
X-ray source according to concept 18.
(Concept 20)
At least one of the plurality of discrete structures is located within 500 microns from an edge of the substrate;
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 an angle between the major axis and a surface normal of the window is: At the intersection of the long axis and the window, less than 85 °,
X-ray source according to any one of concepts 13 to 20.
(Concept 22)
At least one of the plurality of discrete structures is located within 500 microns of an edge of the substrate closest to the window;
X-ray source according to concept 21.
(Concept 23)
The plurality of microstructures of the target, when exposed to the directed electron beam, emit X-rays from a predetermined one of the plurality of discrete structures. Are aligned to transmit through another of the
X-ray source according to any one of concepts 4 to 22.
(Concept 24)
The target is configured such that, when exposed to the directed electron beam, X-rays emitted by a predetermined number of the plurality of discrete structures are selected from the plurality of discrete structures. Being aligned to penetrate one predetermined discrete structure;
An X-ray source according to any one of concepts 21 to 23.
(Concept 25)
A cooling system,
A container for storing a cooling fluid;
A path in the substrate for carrying the cooling fluid;
An additional path for carrying 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 described above,
X-ray source according to any one of concepts 1 to 24.
(Concept 26)
Further comprising a mechanism for rotating the target,
X-ray source according to any one of concepts 1 to 25.
(Concept 27)
A vacuum chamber;
A first window, transparent to X-rays, mounted on the wall of the vacuum chamber;
One or more electron emitters in the vacuum chamber;
With multiple X-ray targets,
Prepared,
Each target has a material selected for its X-ray generation properties,
At least one dimension 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 electron bombardment on the plurality of targets creates a plurality of X-ray sub-sources, whereby the plurality of sub-sources are Being aligned along an axis passing through said first window;
X-ray source.
(Concept 28)
The materials selected for their X-ray generating 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.
An X-ray source according to concept 27.
(Concept 29)
For a predetermined X-ray energy spectrum, the transmittance of at least one X-ray 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;
X-ray source according to any one of concepts 27-29.
(Concept 31)
At least one of the plurality of targets further has a substrate,
X-ray source according to any one of concepts 27-30.
(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.
X-ray source according to any one of concepts 27-31.
(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 comprises a material selected for its x-ray generation properties;
X-ray source according to any one of concepts 27-30.
(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 an electron beam comprises a plurality of electron lenses;
X-ray source according to concept 35.
(Concept 37)
The plurality of X-ray sub-sources generated by the impact of the plurality of electron beams on the plurality of targets are aligned such that a central portion thereof is aligned along an axis passing through the first window. Further comprising means for aligning each of the plurality of electron beams,
X-ray source according to any one of concepts 34-36.
(Concept 38)
At least two adjacent X-ray sub-sources share a common substrate;
X-ray source according to any one of concepts 27-37.
(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 27-38.
(Concept 40)
The X-ray optical element has an obliquely incident X-ray reflector;
X-ray source according to concept 39.
(Concept 41)
The X-ray optical element comprises an X-ray reflector having a multilayer coating;
X-ray source according to concept 40.
(Concept 42)
The x-ray optical element has a thickness of greater than 20 nanometers and has a coated x-ray reflector comprising a high mass density material;
X-ray source according to concept 40.
(Concept 43)
The X-ray optical element has a Walta 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 comprises an ellipsoidal capillary lens, wherein the plurality of focal points are arranged corresponding 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 above a predetermined location in the vacuum chamber;
X-ray source according to concept 39.
(Concept 47)
A further x-ray transparent window mounted on 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;
X-ray source according to any one of concepts 27-46.
(Concept 48)
Further comprising an X-ray detector,
The detector is positioned such that the X-rays emitted by at least one of the plurality of sub-sources impinge on the detector.
X-ray source according to concept 47.
(Concept 49)
A vacuum chamber;
A first window, transparent to X-rays, mounted on the wall of the vacuum chamber;
A first electron beam emitter in the vacuum chamber;
A second electron beam emitter;
The target,
Board and
A first structure having a material selected for its X-ray generation properties;
A second structure having a material selected for its X-ray generation properties;
With a target
Prepare,
X-ray source.
(Concept 50)
A plurality of pairs of electron beam emitters;
Multiple targets,
Board and
A first structure having a material selected for its X-ray generation properties;
A second structure having a material selected for its X-ray generation properties;
Having multiple targets,
Further prepare,
X-ray source according to concept 49.
(Concept 51)
The material of the first structure and the material of the second structure include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, and niobium. , 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.
X-ray source according to any one of concepts 49-51.
(Concept 53)
At least one of the plurality of structures is a thin film coating on a surface of the substrate;
X-ray source according to any one of concepts 49-52.
(Concept 54)
The first structure and the second structure are both thin film coatings on both sides of the substrate;
X-ray source according to any one of concepts 49-53.
(Concept 55)
At least one of the plurality of structures has one or more microstructures,
X-ray source according to any one of concepts 49-54.
(Concept 56)
The one or more microstructures are embedded in the substrate;
X-ray source according to concept 55.
(Concept 57)
One or more microstructures are embedded in at least one of the other plurality of microstructures on an opposite surface of the substrate;
X-ray source according to concept 56.
(Concept 58)
The first electron emitter and the second electron emitter are aligned to impact a plurality of electron beams on both sides of the target;
X-ray source according to concept 49.
(Concept 59)
A method of generating X-rays,
Exposing at least one target to an electron beam formed to impinge on 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 properties;
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 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 of generating X-rays,
Exposing a plurality of targets having an x-ray generating material contained in a single vacuum chamber using 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

  FIG. 13 of the annex 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 a rectangular prism containing x-ray generating material arranged in a regular array. . 13A of the appendix shows a perspective view of the 16 microstructures 700 of this embodiment, 13B of the appendix shows a top view of the same region, and 13C of the appendix shows a side / cross-sectional view of the same region. I have. (For the term "side view / section view" of the present disclosure, a meaning figure is a view of creating a section of an object and then looking at the surface of the section from the side. Of the material, as well as the interior of the material, which can be seen from the side, assuming that the substrate itself is transparent (in the case of diamond, generally applies to visible light).

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

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 make 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 plane of the substrate in a side / cross-sectional view as shown in FIG. The ratio of the total surface area of the structure to the deposited microstructure in contact with the substrate is given by:
If the value of D relative to W and L is small, the ratio will be substantially one. The ratio increases as the thickness increases, and the ratio is 5 for a cube (D = W = L) where five equal faces make thermal contact. If a cap layer of material having similar properties to the substrate in terms of mass density and thermal conductivity is used, the ratio can increase to 6.

The heat conduction is illustrated by typical arrows in FIG. 14A of the Appendix, in which the heat generated by the plurality of microstructures 700 embedded in the substrate 1000 passes through a plurality of microstructures through a bottom surface and a plurality of side surfaces. It is transmitted out of the structure 700 (arrows transmitting through multiple sides in an out-of-plane direction of the drawing are not shown). The amount of heat transferred per unit time (ΔQ) transmitted through a material having an area A and a 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, increasing the surface area, decreasing the thickness, and increasing ΔT all lead to a proportional increase in heat transfer.

  Another embodiment is illustrated in Appendix B 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 from a region near the embedded microstructure 700 May be manufactured according to a design adapted to best remove

  Other embodiments may be understood or devised by those skilled in the art, where, for example, the substrate may be coupled to a heat sink such as a copper block to improve heat transfer. The copper block may then also have multiple cooling paths therein to help draw heat from the block. Alternatively, the substrate can be mounted on a thermoelectric cooler and the 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. Although commercially available devices such as Peltier coolers can generate up to 70 ° C. temperature differences across the device, the overall ability to remove large amounts of heat from a heat source can be limited.

  Alternatively, the substrate may be mounted on a cryogenic cooler, such as a block having a flow path for liquid nitrogen, or in thermal contact with a container of liquid nitrogen or another cryogenic substrate to provide more cooling. Can be supplied. When the substrate comprises a material such as diamond, sapphire, silicon, or silicon carbide, thermal conductivity generally increases with decreasing temperature from room temperature. In such cases, it may be preferable to design the target to withstand these lower temperature cooling.

  FIG. 15 of the annex shows another embodiment in which the plurality of cavities formed in the substrate 1000 (preferably of minimum thickness) are embedded before embedding the x-ray generating material forming the plurality of microstructures 700. It is first coated with an adhesion layer 715. Such an adhesion layer may be appropriate where 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 used). (By adding). In embodiments where an adhesion layer and / or a diffusion barrier layer is used, the materials and materials may be such that the flow of heat from the microstructures 700 to the substrate 1000 is not significantly impeded 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.

  Figure 16 of the annex shows another embodiment in which a conductive layer 725 has been added to the surface of the target. When bombarded by electrons, the extra charge requires a path to return to the ground of the target, which effectively functions as an anode. A target, such as illustrated in FIG. 13 of the accompanying drawings, has a plurality of discrete, unconnected microstructures 700 in an electrically insulated substrate material (such as undoped diamond) and a continuous electron If under impact, large charges can accumulate on the surface. In addition, electrons from the cathode may not collide with or even repel a target having the same energy, thereby reducing X-ray generation.

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

  FIG. 17 of the annex shows another embodiment of the present invention, wherein a plurality of microstructures 702 are buried deeper in the substrate 1000 or buried. Such buried microstructures may be further covered by the deposition of an additional layer 1010, which may be, for example, diamond, to provide the same heat transfer properties as the substrate. This allows heat to be dissipated from all surfaces of the buried microstructure 702. However, in such situations, it may be desirable to provide a path 722 to ground for electrons incident on the structure, which may take the form of a buried conductive layer 726 provided prior to depositing additional layer 1010. It may be. In some embodiments, the conductive layer 726 may be a "via" 727, or a vertical connection, that provides a conductive structure to couple the buried conductive layer 726 to an additional conductive layer 728 on the target surface. , Often in the form of pillars or cylinders, and then additional conductive layer 728 is connected to path 722 to ground.

  FIG. 18 of the annex shows another embodiment of the present invention, wherein the plurality of microstructures has, in turn, a plurality of further structures therein. 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 so that they emit multiple characteristic lines in their entirety. Alternatively, instead of having separate layers, a microstructure having a plurality of materials arranged next to each other to achieve a desired X-ray emission spectrum may be used. Alternatively, instead of having separate layers, microstructures having a uniform or diverse mixture or alloy of two or more materials are used to achieve the desired X-ray emission spectrum. Is 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 sidewalls (not shown) to provide electrical paths to the conductive paths, as shown in Appendix 16 and 17.

  FIG. 19 of the annex shows another embodiment of the present invention, wherein a plurality of microstructures 702 are also embedded in the substrate. However, in this embodiment, instead of first providing a conductive layer and subsequently depositing an additional capping layer, only a single layer 770 selected for a combination of electrical and thermal conductivity properties is provided. It is deposited in this embodiment. This may be, for example, a deposition of carbon nanotubes (atomic number 6) arranged vertically to the surface to carry both heat and electrons from the plurality of buried microstructures 702. This single layer 770 may then be connected to a path 722 to ground, allowing the target to act as the anode of the x-ray generation system. Alternatively, the material of layer 770 may be selected to have aluminum (Al), beryllium (Be), chromium (Cr), or copper (Cu).

  Although several embodiments are shown separately in Appendices 13-13 and various processes for manufacturing them are shown later, the elements of these embodiments may be combined with each other, or It will be apparent to those skilled in the art that it may be combined with other generally known methods of manufacturing targets known in the art. For example, the plurality of buried microstructures 702 of Appendix 19 may also have multiple materials as illustrated in Appendix 18. Similarly, an adhesion layer 715 as illustrated in Appendix 15 may be applied to the fabrication of a plurality of embedded microstructures 700 as illustrated in Appendix 16. The separation of these alternatives is for illustration purposes only and does not limit any particular process.

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

  Similarly, although some embodiments have been described with a microstructure in the shape of, for example, a square prism, multiple manufacturing processes may be performed at angles other than 90 ° depending on the product of the particular process used. Instead of having or having exactly right-angled corners, it can form a plurality of structures that can be rounded, chamfered, or undercut. Embodiments in which the microstructures are substantially similar to the shapes described herein may occur 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 being disclosed.

  Similarly, while the various embodiments disclosed herein may be illustrated with a regular periodic array of multiple microstructures, the relative positions, sizes, and shapes of the discrete microstructures may be regular, periodic, Or need not be uniform. Configurations of multiple microstructures having different sizes and having different distances between the multiple microstructures may also work.

3. Various Microstructure Shapes Certain embodiments of the present invention have been described in the previous sections. However, in addition to variations in layers and structures, embodiments also have multiple microstructures of various sizes and shapes.

  Appendix 20 shows a target region 1011 having two regular arrangements of microstructures 700 and 702, typically in the form of a rectangular prism containing a metallic X-ray generating material, according to one embodiment of the present invention. Is shown. The array is staggered at different lateral depths such that each microstructure is surrounded by "cooler" substrate material when under electron irradiation. The physical separation of the microstructures provides a plurality of small hot spots in the colder, broader material, thereby creating a number of local temperature gradients that rapidly dissipate heat from the microstructures. 20A in the appendix shows a perspective view of the 16 buried microstructures 700 and 9 buried microstructures 702 in this embodiment, 20B in the appendix shows a top view of the same region, and 20C in the appendix shows the same FIG. 4 shows a side / cross-sectional view of the region.

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

  On the other hand, the configuration illustrated in FIG. 21A in the Appendix may only provide a region that is too small to provide effective heat conduction and electric conduction depending on the setting of the electron energy and the material composition.

  To address this, the plurality of buried microstructures 702-B are buried deeper by the substrate 1000, as illustrated in FIG. 21B of the Appendix, and a plurality of buried microstructures 702-B are provided in a path 722 to ground. It can be manufactured to have its own conductive layer 726 connected by vias 727 providing additional electrical connections. This configuration may be preferred in some applications because it provides a long distance between multiple sources of heat and X-rays.

  In some manufacturing processes, the etching process may be adjusted to provide an undercut. [For example, regarding both isotropic and anisotropic etching of diamond, see, for example, S. Hwang, T .; Saito, N .; Fujimori, “New etching process for device using diamond,” Diamond & Related Materials, Vol. 13, pages 2207-2210 (2004)]. An undercut process was selected to etch multiple cavities in the substrate used to form multiple microstructures, using multiple isotropic processes such as electroplating to fill all portions of the cavities. Are formed, a plurality of microstructures “fixed” at predetermined positions may be formed as illustrated in FIG.

  22 of the annex shows a region 1012 of the 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 the substrate 1000. I have. The plurality of microstructures 704 so formed are in the form of trapezoidal columns having X-ray generating material. The arrangement as shown is arranged as a buried arrangement on the surface of the substrate, and a “lip” around the surface or the remaining substrate material better holds the plurality of microstructures 704 in place, It acts to prevent delamination in the event of stress or thermal overload. 22A in the appendix shows a perspective view of the 16 trapezoidal embedded microstructures 704 in this embodiment, 22B in the appendix shows a top view of the same region, and 22C in the appendix shows the side / FIG.

  FIG. 23 of the annex shows a region 1013 of the target having a checkerboard-like 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 in the appendix shows a perspective view of the 25 buried microstructures 700 and 701 in this embodiment, 23B in the appendix shows a top view of the same area, and 23C in the appendix shows a dotted line. FIG. 4 shows a side / cross-sectional view of the same area with multiple recessed areas.

  Appendix 24 shows a region 1014 of a target according to one embodiment of the present invention having an arrangement of a plurality of microstructures 706 in the form of a right cylinder containing X-ray generating material. The array as shown is arranged as an array embedded in the substrate. 24A in the appendix shows a perspective view of the 16 buried microstructures 706 in this embodiment, 24B in the appendix shows a top view of the same area, and 24C in the appendix shows the center of the row of microstructures 706. FIG. 2 shows a side / cross-sectional view of the same area throughout.

  Annex 25 also shows a region 1015 of the target according to one embodiment of the present invention having a dense arrangement of microstructures 708 and 709 in the form of a right cylinder containing the 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, the configuration is such that, when viewed from the side or from the edge, the x-ray source appears to have no "gaps" present in the configuration of FIG. 25A in the appendix shows a perspective view of the 18 buried microstructures 708 and 709 in this embodiment, 25B in the appendix shows a top view in the same region, and 25C in the appendix shows a sense of depth in the same region. FIG. 4 illustrates a side / cross-sectional view;

  Appendix 26 shows a region 1016 of a target according to one embodiment of the present invention having a dense arrangement 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 shows a perspective view of the 18 embedded microstructures 711 and 712 in this embodiment, 26B in the appendix shows a top view of the same region, and 26C in the appendix shows a sense of depth in the same region. FIG. 4 illustrates a side / cross-sectional view;

  Appendix 27 shows a region 1017 of a target according to an embodiment of the invention having a dense arrangement of microstructures 713 and 714 in the form of a tetrahedron containing the X-ray generating material, one surface of which is the substrate. It is substantially coplanar 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 shows a perspective view of the 18 embedded microstructures 713 and 714 in this embodiment, 27B in the appendix shows a top view of the same region, and 27C in the appendix shows a sense of depth in the same region. FIG. 4 illustrates a side / cross-sectional view;

  Annex 28 shows a region 1018 of a target according to an embodiment of the present invention having a combination of the previously described microstructures 700, 701 and 702 in the form of a square prism containing the X-ray generating material. I have. In this embodiment, the layers of microstructures 700 and 701 embedded near the surface form a checkerboard pattern as illustrated in FIG. It also has a buried layer of a plurality of microstructures 702 located below. Similarly, in the case previously described, the microstructures of the buried layer may be large enough to make electrical contact with microstructures 700 and 701 of the upper buried layer, but other microstructures may be used. In embodiments of the present invention, a separate conductive layer that allows charge to escape from the buried microstructure 702 can be manufactured to provide a path to ground. 28A in the appendix shows a perspective view of the forty-eight buried microstructures 700, 701 and 702 in this embodiment, 28B in the appendix shows a top view of the same region, and 28C in the appendix shows the same region. FIG. 3 shows a side / cross-sectional view with a sense of depth.

  Appendix 29 shows a region 1019 of a target according to one embodiment of the present invention having both buried microstructures 716 and buried microstructures 717 in the form of long rectangular prisms containing X-ray generating material. In an embodiment as shown, in alternating layers, long prisms are arranged to extend in directions orthogonal to each other, often in what is referred to as a "stack-of-logs" configuration. ing. As in the previously described case, the plurality of microstructures 717 in the buried layer may be in electrical contact with the microstructure 716 in the upper buried layer, but in other embodiments, the buried microstructure A separate conductive layer that allows charge to escape from 717 can be manufactured to provide a path to ground. 29A in the appendix shows a perspective view of the microstructures 716 and 717 in this embodiment, 29B in the appendix shows a top view of the same area, and 29C in the appendix shows a depth side / cross-section of the same area. FIG.

  Appendices diagram 30 shows a region 1020 of a target according to an embodiment of the present invention having an array of a plurality 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 in the appendix shows a perspective view of the 16 buried microstructures 704 in this embodiment, 30B in the appendix shows a top view of the same region, and 30C in the appendix shows a side / cross-sectional view of the same region. Is shown.

  The manufacture of an area of an embedded sphere, as illustrated at 30 in the annex, may, in some embodiments, have good mechanical stiffness or lower manufacturing costs, but create 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 an X-ray generating material, or a pre-fabricated sphere is deposited on the surface, and It can be covered with a coating material.

  As previously discussed, the various embodiments disclosed herein may be illustrated with a regular periodic or regular arrangement of a plurality of microstructures, but with the relative position, size, And the shape need not be regular, periodic, or uniform. Configurations of multiple microstructures having different sizes and having different distances between the multiple microstructures may also work.

  In some embodiments, various metrics that determine the size and distribution of the plurality of microstructures with the X-ray generating material can be used. The plurality of 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 may be selected to be a certain percentage of the depth (eg, 30% or 50%, etc.) or may be a range of allowed depths. The plurality of microstructures are such that their lateral dimensions L and W do not exceed D (eg, 2 or 3 times) multiplied by more than a specified factor, and each individual microstructure is It can be specified that the structure does not come closer than a predetermined distance d. Alternatively, the plurality of microstructures are such that their lateral dimensions L and W do not exceed the X-ray decay length (the length at which the intensity of the X-ray beam of a particular energy drops by a factor of 1 / e) depending on the application. Can be specified.

  In the most general case, regions 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 with the X-ray generating material. For example, if a plurality of microstructures of tungsten (W) are used with 60 keV electrons, the penetration depth according to Table 2 is 2.41 microns, and a value of D = 1 micron corresponds to a thickness corresponding to 41% of the penetration depth. Will be represented. For a first layer thickness D = 1 micron, as long as the volume fraction of the X-ray generating material relative to the substrate material is approximately 50% in the region of the target that includes the microstructures but does not include the surrounding target substrate. Defining a volume fraction of 50% by weight can be achieved, for example, either by using a checkered arrangement of 23 in the Appendix, or by a more random distribution of microstructures of various sizes and shapes. obtain. Such multiple configurations may provide advantages, for example, with respect to additional surface area for heat transfer.

  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 re-absorption characteristics of the substrate. In some applications requiring specific characteristic lines, a configuration with a lower volume fraction may be preferred. In other variations of the emission spectrum, such as those having different wavelengths, higher volume fractions that increase the 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 the X-ray generating material can be prepared in advance and then dispersed over the surface of the substrate. In particular, where it is desired that the microstructures be arranged in a regular array (as illustrated in FIG. 30 of the Appendix), a process of fixing the microstructures in place is used. obtain. This is followed by a deposition process that covers these spherical microstructures with a thermally conductive material. In some embodiments, this may be a material selected solely for its thermal conductivity properties, but in other cases, the deposited material may benefit from both thermal and electrical conductivity. And the overlying material also serves as a conductive layer providing a path to ground.

  In another embodiment, the dispersion of the microstructures with the X-ray generating material need not be limited to uniform spheres, but may be particles of various sizes and shapes. This is illustrated at 31 in the Appendix, where the region 1021 of the target according to the invention has a variety of multiple microstructures. Similarly, in a similar embodiment, as illustrated in Appendix 32, regions 1022 of the target according to the present invention have microstructures of different sizes and shapes, as well as microstructures of different material compositions. obtain.

  Up to this point, several embodiments have been shown arranged in a planar structure. These are generally easier to implement. Apparatus and process recipes for deposition, etching, and other steps of the planar process are useful for processing devices for micro-electro-mechanical systems (MEMS) applications using planar diamond, and for silicon wafers for the semiconductor industry. Because it is well known in processing.

  However, in some embodiments, surfaces having additional properties in three dimensions (3-D) may be desired. As previously discussed, if the electron beam is greater than the electron penetration depth, the apparent X-ray source size and area will be parallel to the surface, ie, when viewed at a zero degree (0 °) extraction angle. Is minimized (and brightness is maximized). As a result, an apparent maximum brightness X-ray emission occurs when viewed at a take-off angle of 0 °. Emissions from within the x-ray producing material accumulate as it propagates through the material at 0 °.

  However, for a wide target of substantially uniform material, attenuation of the x-rays between multiple sources of x-rays inside the target reduces the extraction angle as the x-rays propagate through the material to the surface. And increases due to the greater distance traveled through the material, often maximizing at or near a 0 ° take-off angle. Thus, any increase in brightness realized by looking 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. Thus, an arrangement may be desired that has a selected distance in relation to the x-ray attenuation length, such that the emitted x-rays do not pass through as much additional material as possible.

  An illustration of one embodiment of a target is shown at 33 in the Appendix. At 33 in the appendix, an x-ray generating area having a single microstructure 2700 is configured at or near the concave edge 2003 of the substrate in contact with the ledge 2002 and is illustrated in 10 of the appendix. Similar to the situation. X-ray generating microstructure 2700 is in the shape of a rectangular bar of X-ray generating material, is embedded in substrate 2000 and emits X-rays 2888 when impacted by electrons 111.

  Bar thickness D (thickness along the surface normal of the target) should be between 1/3 and 2/3 of the electron penetration depth of the X-ray generating material at incident electron energy for optimal thermal performance. Is selected. The thickness D of the bar can also be selected to obtain a desired X-ray source size in the vertical direction. The bar width W 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.

  The length L of the bar as illustrated is approximately four times D, but can be any size, typically 1 / X 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 properties, relative thermal properties, and electron Depending on the amount of heat that is expected to be generated when an impact is applied, an arbitrary value may be selected from the point (p = 0) coplanar with the edge portion 2003 to a maximum of 1 mm.

  An illustration of another embodiment of the present invention is shown at 34 in the Appendix. In this embodiment as illustrated, a target according to the present invention having an X-ray generating area with six microstructures 2701, 2702, 2703, 2704, 2705, 2706 is provided in a recessed substrate in contact with a shelf 2002 It is configured at or near edge 2003 and is similar to the situation illustrated in Appendix 10 and 33. The X-ray generating 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 exposed to X-rays when impacted by the electrons 111. Emit line 2888-D.

  In this embodiment, the total volume of X-ray generating material is the same as in the example of 33 in the previous Appendix. Similarly, the thickness D of the bar (thickness along the surface normal of the target) is equal to that 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. Similarly, in the case shown in Appendix Figure 33, the width W of the bar is selected to obtain the desired source size in the corresponding direction, and as illustrated W is approximately 1.5 of D It is twice. As discussed previously, the bar width W can be substantially smaller or larger depending on the size of the source spot desired.

  However, a single bar 2700 of length L as illustrated in Figure 33 of the Appendix has been replaced by six sub-bars 2701, 2702, 2703, 2704, 2705, 2706, each of 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 surfaces that transfer heat to the substrate, and from the X-ray generation subbar 2701-2706 Increases heat dissipation to the substrate. As illustrated, the separation distance d between the plurality of sub-bars is approximately equal to l, but larger or smaller dimensions may be used, depending on the amount of X-ray absorbed by the substrate and the X-ray It depends on the relative temperature gradient that can be achieved between the particular material of the generating microstructures 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 and relative thermal properties of the substrate material Depending on the amount of heat that is expected to be generated when subjected to an impact with electrons, an arbitrary value may be selected from a point (p = 0) coplanar with the edge portion 2003 to a maximum of 1 mm. .

  In the configuration shown at 34 in the appendix, etc., the total length of the plurality of X-ray generation sub-bars is generally about twice as long as the linear attenuation length of X-rays in the X-ray generation material. It can be selected up to and beyond. 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 incident electron energy for optimal thermal performance. , But can be substantially larger. The thickness D of the bar can also be selected to obtain a desired X-ray source size approximately equal in the 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 FIG. 35 of the annex, wherein the area of the target according to one embodiment of the present invention has an arrangement of microstructures 2790 and 2791 that include an X-ray generating material having a thickness D. 2001 is shown. The arrangement shown is a modified checkerboard of square prisms, but other configurations and arrangements of multiple microstructures may be used.

  Similarly, in 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 height of the steps may be selected to be between one and three times the thickness of the plurality of microstructures. The overall height of all steps may be selected to be equal to or less than the desired X-ray source size along the vertical (thickness direction).

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

  Appendix 36 shows the X-ray emission 2888-S from the stepped embodiment of 35C in Appendix, when impacted by electrons 111. Similarly in other embodiments, the 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 in thermal contact with the substrate 2000, the conduction of heat out of the X-ray material is such that the X-ray material Still larger than the deposited configuration. However, for one surface, the x-ray emission is not attenuated by absorption by other adjacent prisms, but is negligibly attenuated by adjacent substrate materials.

  Thus, the brightness of the X-rays from each prism is also representative of the X-ray emission from the embodiment of FIG. 23 of, for example, Appendix 23, which also shows a plurality of prisms 700 and 701 of X-ray generating material, particularly arranged in a checkered pattern. 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. The rows are attenuated by both the prisms and the substrate material.

  One such embodiment with a target with topography involves first providing a substrate with topography and then embedding a plurality of prisms of x-ray material according to the manufacturing process for planar substrates described above. Can be manufactured by Alternatively, the first steps of forming the cavities filled with the X-ray material can be enhanced to form a step-like topographic structure in the initial flat substrate. In either case, if it is desired to overlay the embedded prism with a particular feature topography, additional multiple alignment steps are used, such as are known to those skilled in the planar process. obtain.

  The plurality of microstructures may be embedded at a distance to the edge of the stairs as illustrated in Appendix 35 and Appendix 36, or (as shown in Appendix 9). It can be embedded flush with the edge. Determining 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 that, for example, heat transfer through five or four surfaces The additional brightness realized by the increase in electron current enabled by can be compared to the additional brightness realized by free space emission or reabsorption through a portion of the substrate material. The additional costs associated with the alignment and overlay steps, and the multiple process steps that may be required to pattern multiple prisms in multiple layers, are considered in comparison to the achievable increase in brightness. May need to be done.

  The embodiments described above relate to various X-ray targets with multiple 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. The configuration is explained. Although these target configurations have been described as being bombarded with electrons to emit X-rays, they have been used as stationary X-ray targets in another conventional source and have been used as a transmission X-ray source 08 in FIG. Either the target 01 or the target 100 of the reflected X-ray source 80 of the appendix 2 can be replaced by a target according to the invention.

  Embodiments as described may be equally well applied to movable X-ray targets, for example, replacing the target 500 of the rotating anode X-ray source 80 of Appendix 6 with a target according to the present invention. It is also possible.

  37 of the annex shows an embodiment of the present invention configured as a rotating anode 2500. A plurality of x-ray generating materials are formed in the outer annulus of the rotating anode 2500 and may be formed by any of the processes described previously. In an embodiment such as that illustrated in Appendix 37, two separate materials are illustrated, each having a different configuration in the form of either annular rings 2508 and 2509 or square structures 2518 and 2519. It has a fine structure.

  Similarly for a conventional rotating anode, the electrons bombard an edge target anode 2500 that can be chamfered just as the conventional rotating anode is chamfered, and the source of the electron beam is An electron beam is directed onto the 2500 chamfered edge 2510 to generate X-rays from the target spot 2501. The target spot 2501 generates X-rays and is heated, but as the target anode 2500 rotates, the heated spot moves away from the target spot 2501 and the electron beam irradiates a cooler portion of the target anode 2500 here. Before being heated again when passing through hot spot 2501, the hot spot has one revolution to cool. By continuously rotating the target anode 2500, a single spot does not get too hot, but may still provide a continuous source of X-rays.

  Similarly in the previously described rotating anode system, to provide additional cooling of the anode, additional rotating paths are provided to the rotating anode to provide bombardment with electrons having higher voltage or higher current density. By making it possible, a brighter X-ray source can be formed. However, if the target material of the rotating anode uses a plurality of microstructures according to the invention disclosed herein, the improved thermal properties may allow for higher electron power loading. This allows for a brighter X-ray source because the electron energy and current can be increased once it is possible to accommodate further thermal loads. Alternatively, thermal advantages to allow a rotating anode source with multiple components that are the same brightness but easier to design, such as lower voltage, lower current, or lower anode rotation speed Can be used.

4. Manufacturing Process The methods for manufacturing a target according to the present invention include the steps outlined in the flow chart at 38 in the Appendix and the cross-sectional views at 39 through 40 in the Appendix. .

4.1. Substrate Selection In a first step, a substrate 3000 of a suitable material is selected. This is indicated by the step designated as "1)" in 39A of the appendix diagram. As mentioned above, this is typically the material of choice for various physical and thermal properties, especially for low mass density, low atomic number, and high thermal conductivity. Several candidates for substrate materials are listed in Table 1 and some have high thermal conductivity (ie, materials with a 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 around 2200 W / (m ° C.), one of the highest values already known for any material. At lower temperatures, around -120 ° C, this value can increase to almost three times higher.

  Wafers CVD grown to 120 mm in diameter and diamond coated to 2 mm in thickness can be purchased from Diamond Materials GmbH, Freiburg, Germany. Silicon substrates coated with diamond or diamond-on-insulator (DOI) substrates are also available, for example, from Advanced Diamond Technologies, Inc. of Romville, Illinois. Or from sp3 Diamond Technologies of Santa Clara, California. Richter Precision, Inc. of East Petersburg, Pennsylvania. Films of diamond-like carbon (DLC), such as those produced by, may also be useful as substrate materials.

  Beryllium can also be a candidate for the substrate material. Due to its low atomic number (atomic number 4), beryllium is very light and is particularly transparent to X-rays, and thus can prevent X-ray emission from multiple microstructures embedded in the substrate. Hard to be the source of the line. Beryllium wafers are available, for example, from American Elements, Inc. of Los Angeles, California. And commercially available from Atomicgic 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. Patterning the Substrate Once the substrate has been selected, as shown at 38 in Appendix, the next step 3100 is to pattern the substrate 3001 as shown at 39A in Appendix. There are several known approaches to patterning diamond for MEMS applications, nanoimprint lithography, and other processes. [For example, H. Masuda et al., "Fabrication of Through-Hole Diamond Membranes by Plasma Etching Using Anodic Polos Alumina Mask", Vol. Ando et al., "Smooth and high-rate reactive ionizing of diamonds", Diamond and Related Materials, Vol. 11 (2002), pp. 824-827 (2002). D. Wang et al., "Precise patterning of diamond films for MEMS application", J. Amer. Material Processing Technology, Vol. 127, pp. 230-233 (2002); Taniguchi et al., "Diamond Nanoimprint Lithography", Nanotechnology, Vol. 13, pp. 592-596 (2002); S. Hwang / T. Saito / N. Fujimori, "New etching process for device using diamond", Diamond & Related Materials, Vol. 13, pages 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 has been previously prepared using 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 acts as a mask.

  A representative plurality of steps for this process step 3100 are the corresponding 39A in the annexed figure shown as "a)", "b)", "2)", "3)", and "4)". This is exemplified by the steps of:

  In step “a)” of FIG. 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 undergo a pattern transfer step such as reactive ion etching (RIE) with oxygen to form a patterned substrate 3001 from the first substrate 3000. In step "4)", mask 3060 is removed, leaving patterned substrate 3001.

  Alternatively, the substrate can be patterned using a conventional multiple lithographic process. These may include coating the substrate with a photoresist, such as HSQ, and exposing the resist using an electron beam or ultraviolet photons to a pattern representing the desired structure to be formed on the wafer. 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 completed, the excess resist is removed, leaving a patterned substrate that is substantially the same as the patterned substrate 3001 shown in step "4)" of Appendix 39A and Appendix 39B. Remains.

  In a variation on the lithographic patterning process described above, the substrate may be coated with a specially selected material that acts as a hard mask for patterning the substrate. In this case, a plurality of steps include coating a hard mask on a substrate, coating a 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. Transfer of the pattern from the hard mask to the substrate, the patterned substrate being substantially the same as the patterned substrate 3001 shown in step “4)” of the FIG. 39A and FIG. 39B. It is to leave the substrate. Such multiple lithographic processes and their variations may be well known to those skilled in the art.

  In other alternatives of the lithographic patterning process described above, the substrate may also be directly ion milled using a machine such as a focused ion beam. 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 to deposit 3300 a material capable of generating X-rays of the desired characteristics into the patterned plurality of cavities. This can be 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, depending on the material. 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, including cesium, barium, gold, platinum, lead, and combinations and alloys thereof, may be selected for use as the X-ray generating material.

  Representative steps for this process step 3300 are illustrated by the corresponding steps of 39B in the annexed figure, indicated by "5)."

  Once the X-ray material has been 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 in 39B of the annex figure shown in "6)" Leaves a plurality of cavities in the patterned substrate 3001, now filled with discrete microstructures 3401 of X-ray material.

4.4. Alternative Adhesion Materials Some materials, when used in combination with certain substrates, may form an interfacial layer that provides good bonding between the two. For example, for selected X-ray materials such as tungsten, CVD deposition 3400 of the tungsten material on a patterned diamond substrate 3001 may cause a plurality of cavities in the diamond to form a strong carbon-bonded bond at the boundary between tungsten and carbon. May be suitable for filling with tungsten to form However, with 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 the diamond substrate, requires two materials. Improve the mechanical integrity of the anode, both by improving the adhesion between them and, in some cases, also by preventing material from diffusing from one region to the other. May be preferred.

  Exemplary steps for this process step are illustrated by the corresponding steps in 40 of the annexed drawings labeled "5)", "5a)", "6a)", and "7a)". ing.

  At 40 in the annex, starting with the patterned substrate 3001, step "5a)" illustrates the deposition of a suitable adhesion layer 3350 on the patterned substrate 3001. Exemplary adhesion layer 3350 can be, for example, a layer of chromium (Cr) or titanium (Ti) when used with copper (Cu) as an X-ray material. Other materials may include a carbide alloy of the target material, such as copper carbide (CuC) for copper or aluminum carbide (AlC) for aluminum. Further, other materials known to those skilled in the art having good adhesion to both materials may be used. As an example, molybdenum is often used as a barrier layer for copper. Further, multiple material layers, such as a titanium carbide (TiC) bilayer or a chromium carbide (CrC) bilayer, can be used as the adhesion layer. The thickness of the adhesion layer can vary with the choice of X-ray and substrate materials, but is typically on the order of 10 nm thick. Once deposited, the deposition step may be followed by a carbonization step to form a carbonized compound with the substrate. In other embodiments, the carbonized material may be directly deposited to provide an adhesion layer.

4.5. Overcoat film Once the substrate has been patterned and filled with cavities to form microstructures of the X-ray material, the next step is to ensure that electrons impinging on the X-ray material have a path to ground. This is the deposition of a conductive layer.

  A representative illustration for this process step 3700 is shown by the corresponding results in 39B in the annexed figure labeled "7)."

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

  The plurality of deposition techniques can include any number of various techniques, 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 or cap layer may also be deposited.

  A representative illustration for this process step 3900 is illustrated by the corresponding results of 39B in the annex figure labeled "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 plurality of materials such as silicon carbide (SiC), chromium (Cr), molybdenum (Mo), rhodium (Rh), and palladium (PD). The material can be 100 nm minimum, or 50 microns maximum.

  The plurality of deposition techniques can include any number of various techniques, 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.

  To have good adhesion to the underlying layer, the deposition of the cap layer can be performed after the deposition of an adhesion layer, such as titanium carbide (TiC), which forms the seed layer for diamond growth. The deposition 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 target, indicated by “8)” in Appendix B, 39B, will contain multiple finely divided X-ray generating materials suitable for use as X-ray source targets. A substrate having a structure.

  Although certain process steps have been described in a particular order, it should be understood that certain steps may be performed in a different order or in combination with one another to achieve similar results. is there.

For example, while it has been described that the deposition of the conductive layer occurs before the deposition of the cap layer, a layer that combines these functions (ie, a conductive cap layer), such as that illustrated in Appendix Figure 19, is used. . Similarly, some of the multiple process steps may be repeated to deposit multiple layers of target material as illustrated in Appendix FIG.

Further, a multi-layer microstructure, such as illustrated in FIG. 21 of the Appendix, may be formed by repeating a plurality of 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 Figure 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 Figure 22A]
[Appendix Figure 22B]
[Appendix Figure 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 Fig. 39A]
[Appendix Figure 39B]
[Appendix Figure 40]

Claims (22)

A vacuum chamber including a first window transparent to X-rays;
One or more electron emitters in the vacuum chamber;
A plurality of X-ray targets in the vacuum chamber ;
At least one X-ray optical element ;
Each X-ray target has a first material that produces X-rays in response to electron bombardment, wherein at least one dimension of the first material is less than 20 microns;
The one or more electron emitters and the plurality of X-ray targets are aligned such that electron bombardment on the plurality of X-ray targets creates a plurality of X-ray sub-sources, whereby the plurality of X-ray sub-sources are arranged. the line subsource are aligned with one another along an axis passing through the first window,
The at least one x-ray optical element is arranged such that x-rays emitted by a first x-ray sub-source are directed by the at least one x-ray optical element onto a second x-ray sub-source. Be done
X-ray source. The at least one X-ray optical element includes an oblique incidence X-ray reflector, an X-ray reflector having at least one multilayer coating, a coated X-ray reflector having a thickness of more than 20 nanometers, a Walter lens, a polycapillary lens, And at least one of an ellipsoidal capillary lens,
The X-ray source according to claim 1 . The at least one X-ray optical element further comprises a second X-ray optical element;
The second X-ray optical element is configured such that X-rays emitted by one of the plurality of X-ray sub-sources enter the second X-ray optical element and are directed to a predetermined location in the vacuum chamber. Placed to be attached,
The X-ray source according to claim 1 . The first 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.
X-ray source according to any one of claims 1 to 3. For a predetermined X-ray energy spectrum, the transmittance of at least one X-ray of the plurality of X-ray targets is greater than 50%;
X-ray source according to any one of claims 1 to 4. The predetermined X-ray energy spectrum corresponds to at least one characteristic line of at least one X-ray sub-source;
An X-ray source according to claim 5 . At least one of the plurality of X-ray targets has a substrate;
X-ray source according to any one of claims 1 to 6. The substrate has a second 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 7 . The first material is on the substrate in the form of a thin film;
An X-ray source according to claim 8 . At least one X-ray target of the plurality of X-ray targets has a plurality of discrete structures embedded in a substrate having a second material having a thermal conductivity greater than 0.1 Wm ^-1 ° C ^-1 .
X-ray source according to any one of claims 1 to 6. The plurality of discrete structures are embedded within a depth of less than 100 microns at a surface of the substrate;
An X-ray source according to claim 10 . The plurality of discrete structures are arranged in a linear array;
An X-ray source according to claim 10 . The linear array has a major axis and a minor axis, the major axis is aligned with the first window, and the angle between the major axis and a surface normal of the first window is Less than 85 ° at the intersection of the major axis and the first window;
An X-ray source according to claim 12 . Means for directing one or more electron beams from the one or more electron emitters to one or more locations on the at least one X-ray target to form the plurality of X-ray sub-sources. Further comprising,
X-ray source according to any one of claims 10 to 13 . The means for directing one or more electron beams comprises at least one of a plurality of electron lenses, a plurality of electrostatic lenses, and a plurality of magnetic lenses;
An X-ray source according to claim 14 . All central portions of the plurality of X-ray sub-sources generated by the impact of one or more electron beams on the at least one X-ray target are aligned along an axis passing through the first window. Be done
An X-ray source according to claim 14 . The means for directing one or more electron beams is configured to focus the one or more electron beams to a spot size of at least one dimension less than 30 microns;
X-ray source according to any one of claims 14 to 16 . At least two adjacent X-ray sub-sources share a common substrate;
X-ray source according to any one of claims 1 to 17. The vacuum chamber further includes a second window transparent to X-rays;
The second window is arranged such that the plurality of X-ray sub-sources are aligned along a line passing through both the first window and the second window.
X-ray source according to any one of claims 1 18. Further comprising an X-ray detector,
The X-ray detector is aligned such that the X-rays emitted by at least one of the plurality of X-ray sub-sources strike the X-ray detector;
An X-ray source according to claim 19 . A vacuum chamber including a first window transparent to X-rays and a second window transparent to X-rays;
One or more electron emitters in the vacuum chamber;
A plurality of X-ray targets in the vacuum chamber;
With
Each X-ray target has a first material that produces X-rays in response to electron bombardment, wherein at least one dimension of the first material is less than 20 microns;
The one or more electron emitters and the plurality of X-ray targets are aligned such that bombardment of electrons on the plurality of X-ray targets produces a plurality of X-ray sub-sources, whereby the plurality of X-rays are generated. X-ray sub-sources are aligned with each other along an axis passing through the first window, and the second window is formed by the plurality of X-ray sub-sources of the first window and the second window. Positioned so that they are aligned along a line that passes through both,
X-ray source. Further comprising an X-ray detector,
The X-ray detector is aligned such that the X-rays emitted by at least one of the plurality of X-ray sub-sources strike the X-ray detector;
An X-ray source according to claim 21.