JP7080236B2 - Radioactive source equipment and methods, lithography equipment and inspection equipment - Google Patents

Description

Cross-reference to related applications
[0001] The present application claims the priority of European Patent Application No. 16203624.8 filed on December 13, 2016, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a radiation source device and a method of generating radiation. The present invention further relates to EUV optical systems that include such sources. The present invention further relates to a device manufacturing method and an inspection method.

[0003] A lithographic device is a machine that applies a desired pattern on a substrate, usually on a target portion of the substrate. Lithographic devices can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, also called a mask or reticle, can be used to generate the circuit patterns formed on the individual layers of the IC. This pattern can be transferred to a target portion (eg, including a portion of a die, or one or more dies) on a substrate (eg, a silicon wafer). Usually, the pattern transfer is performed by imaging on a radiation-sensitive material (resist) layer provided on the substrate. Generally, a single substrate contains a network of adjacent target portions that are continuously patterned. Lithography is widely recognized as one of the key steps in the manufacture of ICs and other devices and / or structures. However, as the dimensions of features created using lithography become smaller, lithography is becoming an even more important factor in enabling the manufacture of small ICs or other devices and / or structures.

[0004] It has been proposed to use extreme ultraviolet (EUV) radiation sources to reduce the exposure wavelength and therefore to reduce the minimum printable size. EUV radiation is electromagnetic radiation with wavelengths in the range of about 1-100 nm. For lithographic purposes, use wavelengths in the range of 5-20 nm, such as wavelengths in the range of 13-14 nm, or wavelengths in the range of 5-10 nm, such as 6.7 nm or 6.8 nm. Has been further proposed.

[0005] Further, such short wavelength radiation is also useful for small structure inspections for characterizing, for example, by reflected light measurements and / or scatometry. U.S. Patent Application Publication No. 20160282282 proposes to use EUV radiation to measure properties such as CDs and overlays of target structures. Spectral reflected light measurements are made using radiation scattered at zero and / or higher diffraction order. The diffracted signal is further enhanced with a conical mount between the EUV optical system and the substrate. The content of the prior application is incorporated into this disclosure for reference.

Possible sources for EUV radiation include, for example, laser-generated plasma sources, discharge plasma sources, or sources based on synchrotron radiation provided by electron storage rings. The laser-generated plasma source uses a high-energy laser to generate plasma at a target made of suitable fuel material. Examples of LPP sources are described in published patents such as US Patent Application Publication No. 20142464087 (Rafac et al.) And US Patent Application Publication No. 2014368802 (Yakunin et al.). The contents of these documents are incorporated herein by reference. In these examples, liquid tin droplets are used as targets to generate EUV emission plasma.

[0007] A major challenge in the deployment and application of EUV sources for commercial use is to obtain higher production of desired radiation. At the LPP source, a portion of the light in each pulse of laser radiation is reflected by the fuel material and plasma. This has two drawbacks. First, the unabsorbed light does not contribute to the production of the desired EUV radiation, which is wasted. Second, given the high power of the laser beam, the reflected light can damage peripheral optics as well as seed lasers and laser amplifiers. As a conventional step to improve absorption, a prepulse of radiation is used to prepare the target, eg, to convert liquid droplets into flatter and larger and / or mist. Both patent documents cited above aim for further improved conversion efficiency by preparing the target with additional radiation pulses. U.S. Patent Application Publication No. 20142464087 modifies the properties of some of the targets involved in the absorption of main pulse laser radiation, for example, by irradiating the main pulse with additional prepulses of different wavelengths. In U.S. Patent Application Publication No. 2014368802, prepulse radiation is applied in a particular direction to give the target a desired three-dimensional shape or orientation, whereby the main pulse radiation is tilted with respect to the surface rather than normal. It is incident on the surface of the fuel material in the direction in which it is radiated to enhance absorption.

Nevertheless, the problem of reflection and how to increase the efficiency of conversion to EUV radiation remains significant.

[0009] EUV radiation sources using solid Sn target materials are described in "Efficient laser-produced plasma extreme ultraviolet sources using grooved Sn targets" by S.S. Harilal et al. Of APPLIED PHYSICS LETTERS 96, 111503 (2010), doi: 10.1063 / 1.3364141. It has been disclosed. Grooves larger than the focus beam of laser radiation are designed to confine the plasma and enhance it in the EUV generation zone.

[0010] It is an object of the present invention to address one or more of the above problems, in particular in the design of radiation sources, including EUV radiation sources.

[0011] The present invention provides an apparatus for providing the first radiation in the first frequency band. This device
-Structured to guide the second radiation in the second frequency band to the target to cause the generation of the first radiation, and-to guide the third radiation to the target before and / or during the transmission of the second radiation. The third radiation is configured to generate an electromagnetic field with a spatial distribution of energy containing numerous peaks and troughs across the target, causing spatial variation corresponding to the characteristics of the target. Includes the system, sent to.

[0012] The radiation in the first frequency band may be, for example, EUV radiation having a wavelength in the range of 1 nm to 100 nm, for example, a wavelength in the range of 5 nm to 20 nm.

[0013] It has been recognized by the inventors that creating a grid structure at the target of the LPP source increases the absorption of laser radiation and enhances the conversion efficiency of the source. The inventors have also further recognized that radiation with appropriate spatial variation can be used to achieve the same effect as a lattice etched into a solid metal. The target can be prepared, for example, from drops of liquid fuel material, but the invention is not limited to liquid fuel material. The third emission may be the same as or attached to the prepulse emission used to prepare the target for the main pulse emission.

[0014] In photonics, it is generally known that the reflection of radiation by a metal target can be affected by the etching of the lattice structure onto the target surface. For example, so-called surface plasmon polaritons can be excited to the surface of the fuel material if the etched periodic grid configuration is properly adjusted to the characteristics of the incident laser emission. This corresponds to the surface-coupled vibration of a free charge carrier in the sense that more incident light is absorbed than when the light wave is incident on a flat interface. The physics of surface plasmon polaritons is described in "Plasmonics: Fundamentals and Applications" by S.A. Maier in Springer Business & Science Media, LLC (2007). Surface plasmon polaritons are just one example of the types of phenomena that can be utilized to increase conversion efficiency in LPP sources. The physics of laser excitation of metals is generally, for example, "Physics of ultra-short laser interaction with matter: From phonon excitation to ultimate transformations" by E.G.Gamaly and A.V.Rode in Prog.Quant.Electron.37, 215-323 (2013). "It is described in.

[0015] The present invention further provides an EUV optical device comprising a radiation source and an EUV optical system. Radioactive sources include the apparatus according to the invention described above. The EUV optical device may be, for example, a lithography device, and the EUV optical system includes a projection system for applying a pattern to a substrate using EUV radiation from a radiation source. The EUV optical device may be, for example, an inspection device, where the EUV optical system is a lighting system for directing EUV radiation from a radiation source to the structure of interest and collecting the EUV radiation after interaction with the structure. including.

[0016] The present invention further provides a method of producing a first radiation in the first frequency band, wherein the second radiation in the second frequency band is guided by a target to cause the generation of the first radiation. This method further comprises delivering a third radiation to the target before and / or during the delivery of the second radiation, which has a spatial distribution of energy with numerous peaks and valleys across the target. It creates an electromagnetic field that causes spatial variation corresponding to the characteristics of the target.

[0017] These and other aspects of the invention will be understood by those of skill in the art with consideration of embodiments shown in the accompanying drawings, as described below.

[0018] Some embodiments of the present invention will be described below, by way of example only, with reference to the accompanying schematic.
FIG. 1 schematically shows a lithography device having a reflective projection optical system as an example of an optical device using EUV radiation. FIG. 2 is a more detailed view of the device of FIG. 1 in an embodiment having an LLP source device for the generation of EUV radiation. FIG. 3 is a schematic block diagram of a configuration for transmitting the second radiation, the third radiation, and the prepulse radiation in the LPP radiation source device according to the embodiment of the present invention when viewed along the path of the target. Is. FIG. 4 shows a) the principle of generation of the third radiation and b) the effect of the third radiation in the radiation source device of FIG. FIG. 5 shows various time points during operation of the radiation source device according to the embodiment of the present invention when viewed from a direction crossing the path of the target. FIG. 6 shows one mechanism in the embodiment of the invention in which absorption of second radiation can be increased by the formation of surface plasmon polaritons. FIG. 7 shows three variations of the mechanism of FIG. 6 representing a further embodiment of the invention. FIG. 8 shows the timing of the second radiation, the third radiation, and the prepulse radiation in the embodiment of the present invention. FIG. 9 shows the timing of the second radiation, the third radiation, and the prepulse radiation in the embodiment of the present invention. FIG. 10 shows the timing of the second radiation, the third radiation, and the prepulse radiation in the embodiment of the present invention. FIG. 11 shows (a) the principle of generation of the third radiation and (b, c) the effect of the third radiation in another embodiment of the radiation source device according to the present invention. FIG. 12 is a schematic view of an inspection device including a radiation source device according to the present invention.

[0019] Throughout these drawings, the same reference numerals indicate similar or corresponding features.

[0020] Before describing the radiation source device in detail, a lithography device having a reflected optical system will be described as an example of an EUV optical device to which the present invention can be applied.

[0021] FIG. 1 schematically shows a lithography apparatus 100 including a radiation source module SO according to an embodiment of the present invention. This lithography device
-A lighting system (illuminator) IL configured to regulate radiation beam B (eg, EUV radiation), and
-With a support structure (eg, mask table) MT configured to support the patterning device (eg, mask or reticle) MA and coupled to a first positioner PM configured to accurately position the patterning device. ,
-A substrate table (eg, a wafer table) WT configured to hold a substrate (eg, a resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate.
-A projection system (eg, a refraction projection lens system) configured to project a pattern attached to the radiation beam B by the patterning device MA onto a target portion C (eg, including one or more dies) of the substrate W. Equipped with PS.

[0022] As a lighting system IL, refraction, reflection, magnetic, electromagnetic, electrostatic, or other types of optical components, or theirs, to guide, shape, or control radiation. It can include different types of optical components such as any combination.

[0023] The support structure MT holds the patterning device MA in an manner depending on other conditions such as the orientation of the patterning device, the design of the lithography device, and whether or not the patterning device is held in a vacuum environment. .. The support structure can hold the patterning device using mechanical, vacuum, electrostatic or other clamping techniques. The support structure may be, for example, a frame or table that can be fixed or movable as needed. The support structure can reliably place the patterning device in the desired position, eg, with respect to the projection system.

[0024] The term "patterning device" should be broadly interpreted to refer to any device that can be used to pattern the cross section of a projected beam, such as creating a pattern within the target portion of the substrate. .. The pattern attached to the radiated beam corresponds to a specific functional layer in the device created in the target part such as an integrated circuit.

The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are known in lithography and include mask types such as binary, alternative phase shift, and attenuated phase shift, as well as various hybrid mask types. In one example of a programmable mirror array, a matrix array of small mirrors is used, where each small mirror can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirror patterns the radiated beam reflected by the mirror matrix.

Projection systems, such as lighting systems, are refracting, reflective, magnetic, electromagnetic, and electrostatic optics suitable for the exposed radiation used or for other factors such as the use of vacuum. It should be broadly construed as including any type of projection system, including systems, or any combination thereof. It may be desirable to use a vacuum for EUV radiation, as the gas may absorb too much radiation. Therefore, a vacuum environment can be provided for the entire beam path using vacuum walls and vacuum pumps.

[0027] As shown herein, the lithography apparatus may be of a reflective type (eg, one that employs a reflective mask).

[0028] The lithography apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such a "multi-stage" machine, additional tables can be used in parallel, or the preparation process can be performed on one or more tables while another one or more tables are used for exposure. You can also.

[0029] Referring to FIG. 1, the illuminator IL receives an extreme ultraviolet radiation beam from the source module SO. Methods of producing EUV light include converting the material into a plasma state having at least one element such as, for example, xenon, lithium or tin and having one or more emission lines within the EUV range. However, it is not always limited to this. One such method, often referred to as laser-generated plasma (“LPP”), is to irradiate a fuel such as a droplet, stream or cluster of material with the required ray-emitting chemical element with a laser beam. By doing so, the required plasma can be generated. The source module SO may be part of an EUV radiation system that includes a laser (not shown in FIG. 1) for providing a laser beam that excites fuel. The resulting plasma emits output radiation (eg, EUV radiation), which is collected using a radiation collector located within the source module. The laser and radiation source modules may be separate components, for example, if a CO2 laser is used to provide a laser beam for fuel excitation.

[0030] In such cases, the laser is not considered to form part of the lithography equipment and the emitted beam is beam delivery from the laser to the source module, including, for example, a suitable induction mirror and / or beam expander. Can be sent using the system. In other cases, for example, if the source is a discharge-generating plasma EUV generator (often referred to as a "DPP source"), the source can also be an integral part of the source module.

The illuminator IL can include an adjuster that adjusts the angular intensity distribution of the radiated beam. In general, at least the outer and / or inner radial ranges (usually referred to as σ-outer and σ-inner, respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. In addition, the illuminator IL can include various other components such as facet fields and pupil mirror devices. By adjusting the radiated beam with an illuminator, the cross section of the radiated beam can have the desired uniformity and intensity distribution.

[0032] The radiated beam B is incident on the patterning device (eg, mask) MA held on the support structure (eg, mask table) MT and is patterned by the patterning device. After being reflected from the patterning device (eg, mask) MA, the radiating beam B passes through the projection system PS, which focuses the beam on the target portion C of the substrate W. A substrate table such that the second positioner PW and the position sensor PS2 (eg, an interferometer device, a linear encoder, or a capacitance sensor) are used to position various target portions C in the path of the radiation beam B, for example. The WT can be moved accurately. Similarly, the first positioner PM and another position sensor PS1 can be used to accurately position the patterning device (eg, mask) MA with respect to the path of the radiation beam B. The patterning device (eg, mask) MA and the substrate W may be aligned using the mask alignment marks M1 and M2 and the substrate alignment marks P1 and P2.

An EUV film (eg, pellicle PE) is provided to prevent contamination of the patterning device by particles in the system. Such pellicle may be provided in the indicated arrangement and / or other arrangement. An additional EUV film SPF may be provided as a spectral purity filter, which can operate to filter unwanted emission wavelengths (eg, DUVs). Such undesired wavelengths can affect the photoresist on the wafer W in an undesired way. The SPF can optionally also help prevent contamination of the projection optics within the projection system PS by particles released during degassing (or by providing a pellicle instead of the SPF to do this). May be good). Any of these EUV films may include any EUV film disclosed herein.

[0034] The equipment shown can be used in a variety of modes. In scan mode, the patterning device support (eg, mask table) MT and substrate table WT are scanned synchronously while the pattern attached to the radiated beam is projected onto the target portion C (ie, single dynamic exposure). ). The speed and direction of the substrate table WT with respect to the patterning device support (eg, mask table) MT can be determined by the (reduced) magnification and image inversion characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target area (non-scan direction) during a single dynamic exposure, while the length of the scan operation limits the height of the target area (scan direction). It will be decided. Other types of lithography equipment and operating modes are also possible, as is well known in the art. For example, the step mode is known. In so-called "maskless" lithography, the programmable patterning device is kept stationary but the pattern changes and the substrate table WT is moved or scanned.

[0035] Combinations and / or variations of the above-mentioned usage modes, or completely different usage modes can also be adopted.

[0036] FIG. 2 shows in more detail an embodiment of a lithography apparatus including a radiation source apparatus having the form of a radiation system 42, a lighting system IL and a projection system PS. The radiation system 42 shown in FIG. 2 is of a type that uses a laser-generated plasma as a radiation source. EUV radiation may be generated by gas or vapor, such as Xe gas, Li vapor or Sn vapor. This gas or vapor produces a very hot plasma to emit radiation within the EUV range of the electromagnetic spectrum. Very hot plasmas are produced, for example, by using CO ₂ laser light to induce at least a partially ionized plasma by photoexcitation. In one embodiment, Sn is used to generate a plasma to emit radiation within the EUV range.

[0037] The radiation system 42 embodies the function of the radiation source SO in the apparatus of FIG. The radiation system 42 comprises a radiation source chamber 47, which in this embodiment substantially encloses only the EUV radiation source, but in the example of FIG. 2, a normal incident collector (eg, a multilayer mirror). ) Is also enclosed.

[0038] As part of the LPP source, a laser system 61 is constructed and arranged to provide a laser beam 63 delivered by the beam delivery system 65 through an opening 67 provided within the collector 50. Further, the radiation system includes a material 69 such as Sn or Xe supplied by the target material source 71. In this embodiment, the beam delivery system 65 is arranged to establish a beam path that is substantially focused at the desired plasma forming position 73.

[0039] During operation, the target material 69, sometimes referred to as fuel, is supplied by the target material source 71 in the form of droplets. A trap 72 is provided on the opposite side of the radiation source chamber 47 to capture fuel that does not change to plasma for any reason. When such droplets of the target material 69 reach the plasma forming position 73, the laser beam 63 collides with the droplets and EUV emission plasma is formed in the source chamber 47. In the case of a pulsed laser, it involves timing the pulse of the laser emission to coincide with the path of the droplet through position 73. They produce a highly ionized plasma with an electron temperature of several ¹⁰⁵ K. The energy radiation generated during the deexcitation and recombination of these ions comprises the desired EUV emitted from the plasma at position 73. The plasma forming position 73 and the aperture 52 are arranged at the first and second focal points of the collector 50, respectively, and the EUV radiation is focused on the intermediate focal point IF by the normal incident collector mirror 50.

[0040] As shown in FIG. 2 by the radiated beam 56, the radiated beam emitted from the source chamber 47 crosses the lighting system IL via the so-called normal incident reflectors 53, 54. The normal incident reflector guides the beam 56 onto a patterning device (eg, reticle or mask) positioned on a support (eg, reticle or mask table) MT via the pellicle PE. A patterned beam 57 is formed, which is imaged by the projection system PS on a substrate supported by a wafer stage or substrate table WT via reflective elements 58, 59. More elements than those shown may usually be present in the lighting system IL and the projection system PS. For example, there may be one, two, three, or four or more reflective elements instead of the two elements 58 and 59 shown in FIG.

As will be apparent to those skilled in the art, reference axes X, Y and Z are defined for measuring and describing the shape and operation of the device, its various components and the radiated beams 55, 56, 57. be able to. In each part of the device, a local reference frame for the X, Y or Z axis can be defined. The Z-axis substantially coincides with the direction of the optical axis O at a predetermined point in the system and is substantially perpendicular to the plane of the patterning device (reticle) MA and the plane of the substrate W. In the radiation source device (radiation system) 42, the X-axis almost coincides with the direction of the fuel stream (69, described below), while the Y-axis is orthogonal to it and points out of the paper as shown. On the other hand, around the support structure MT that holds the reticle MA, the X-axis generally crosses the scanning direction alongside the Y-axis. For convenience, in this region of the schematic of FIG. 2, the X-axis points out of the paper as shown. These indications are common practice in the art and are incorporated herein for convenience. In principle, any reference frame may be selected to illustrate the device and its operation.

[0042] In addition to the desired EUV radiation, the plasma also produces wavelengths of other radiation, such as those within the visible UV and DUV range. IR (infrared) radiation also comes from the laser beam 63. Non-EUV wavelengths are not desirable in the lighting system IL and the projection system PS, and various measures may be developed to block non-EUV radiation. As schematically shown in FIG. 2, EUV membrane filters in the form of spectral purity filters SPF can be applied upstream of virtual light source points for IR, DUV and / or other undesired wavelengths. In the particular example shown in FIG. 2, two spectral purity filters are shown, one in the source chamber 47 and the other in the output of the projection system PS. In a substantial embodiment, only one spectral purity filter may be provided and may be in any arrangement or anywhere between the plasma forming position 73 and the wafer W.

[0043] As mentioned above, lithographic equipment is not the only type of EUV optical system to which the radiation source equipment and methods of the present disclosure can be applied. In particular, inspection equipment and methods can be envisioned using any improved EUV source. As an example of the EUV inspection apparatus, reference is made to the publication of US Patent Application Publication No. 20160282282, which is incorporated in the present specification as a reference. An example of an inspection device from US Patent Application Publication No. 20160282282 is shown in FIG. 12 described below.

[0044] FIG. 3 schematically shows the main components of the radiation source device 300. The radiation source device 300 can be used as a radiation system 42 in the lithography device of FIG. 2, in another lithography device, or in another EUV optical system such as an inspection device. On the right side, the source chamber 47 is schematically shown with a small drop of target material 69 and a fuel stream containing the plasma forming position 73. The figure in FIG. 3 is along the X axis, i.e., along the direction of the fuel stream. A diagram across the direction of the fuel stream can be seen in FIG. 5, described below.

[0045] Radiation including the first radiation 302 having the desired EUV wavelength is emitted by the plasma formed at the plasma forming position 73. To generate the plasma, a second emission 304 containing a main pulse of laser emission is provided by a first laser source 306 that can be part of the laser system 61 in the example of FIG. A prepulse emission 308 is provided by a second laser source 310 which can be part of the same laser system as the laser source 306 to prepare the target material 69 for interaction with the main pulse of the laser emission. The generation of main pulse and prepulse radiation is not provided in this disclosure, but may be found, for example, in the publications described above in US Patent Application Publication No. 20142464087 and US Patent Application Publication No. 2014368802. Can be done.

[0046] In the illustrated example, the second emission 304 and the prepulse emission 308 are guided using the beam coupling optics 312 and the focus configuration 314. Although not seen in the orientation shown in FIG. 3, the prepulse emission beam 308 usually collides with a droplet of target material 69 earlier in flight than the main pulse containing the second emission 304. Therefore, the pre-pulse radiating beam can be focused on a displaced arrangement on the X-axis relative to the main pulse. The controller 316 synchronizes the operations of the first laser source 306 and the second laser source 310 to obtain appropriate timing for each droplet of the fuel material 69. The delivery of droplets is repeated at high frequencies (eg, tens of kilohertz (eg, 50 kHz)) with the pulse operation of the laser sources 306, 310. As a result, the desired EUV emission 302 is emitted in pulses with the same frequency.

[0047] As in the previous publication of US Patent Application Publication No. 20142464087, the present disclosure adjusts the target material 69 in anticipation of the delivery of the third radiation, enhancing the absorption of the second radiation 304. While increasing the efficiency of the generation of the EUV first radiation 302, according to the principles of the present disclosure, the third radiation is provided so that the target produces an electromagnetic field with an energy distribution containing multiple peaks and valleys across the target. .. The spatial variation in this electromagnetic field results in a spatial variation corresponding to the characteristics of the target. An energy distribution with multiple peaks and valleys, also called repetitive spatial variation, can be distinguished from the periodic energy distribution. In this periodic energy distribution, the radiated beam has a central peak of energy that diminishes towards the periphery of the beam. As further described below, the spatial variation may be, for example, a one-way or two-way periodic or repetitive variation that applies a grid pattern to one or more properties of the target. This grid pattern can be tuned to enhance the absorption of the second radiation by the fuel material to increase the efficiency of the EUV source device.

[0048] In the example of FIG. 3, two radiating beams 328a and 328b are shown, both of which form a third radiating 328 that collides with the target material. Radioactive sources 330a and 330b generate these beams. As further described below, the third emission may collide with the target material before or during the irradiation of the main pulse of the laser emission (second emission 304). In the following description, the third radiation is described as "lattice radiation" based on its function. The timing of the transmission of the grid radiation is synchronized with the transmission of the main pulse and pre-pulse radiation by the controller 316.

[0049] In the illustrated example, each beam 328a / 328b of grid radiation has its own focus configurations 332a and 332b. In other embodiments, the grid radiation may pass through the same focus configuration 314 as the main pulse radiation and / or the prepulse radiation. In the illustrated example, the grid emission beam is positioned on either side of the main pulse emission beam. In other embodiments, the grid radiation may be sent from one side or the other side of the main pulse radiation. Both the second radiation (main pulse), the pre-pulse radiation and the third radiation (lattice radiation) may be sent substantially along the z-axis or at an angle of inclination with respect to the z-axis as shown.

[0050] FIG. 4 (a) shows the principle of irradiating the target of the example of FIG. 3 with lattice radiation 328. Beams 328a and 328b of lattice radiation that meet each other at an angle θ in the vicinity of the target 402 are shown. In this example, the target 402 is assumed to be a droplet of fuel material 69 already prepared by irradiation with prepulse radiation 308. In some embodiments, for example, prepulse radiation 308 is used to transform a substantially spherical droplet into the flat "pancake" shape schematically shown in the drawings. In other embodiments, the prepulse radiation may be sufficient to disperse the liquid fuel material into smaller droplets or vapor mist.

[0051] For the sake of brevity, each of the beams 328a and 328b is assumed to contain coherent radiation with plane wave planes schematically shown in 404a and 404b. Interference between beams on the surface of the target 402 creates an interference pattern with periodic or repetitive spatial variations in intensity over the surface of the target 402. Physically, the two radiating beams interfere to create an electromagnetic field with a spatial distribution of energy, which is schematically shown as spatial variation 406. FIG. 4 (b) shows the surface of the target 402 with lines of a grid pattern formed by spatial variation 406. Each shadow line in FIG. 4 (b) represents, for example, a high energy band in an electromagnetic field with a lower intensity region in between. Although a simple band of high energy is shown, it will be understood that the electromagnetic field may have, for example, sinusoidal fluctuations in energy.

Interfering between two lattice radiating beams with a constant angle is a simple way to create an electromagnetic field with the desired spatial variation in energy. In principle, any method may be used, and another method will be described below with reference to FIG.

[0053] FIG. 5 is a schematic diagram of the interference between the various radiation beams and the fuel material at five time points during the operation of the radiation source device 300. These time points are displayed as t1 to t5. It will be appreciated that FIG. 5 generally shows, for each time point, each diagram of a particular target in each arrangement along the X direction, which is the direction of the stream of fuel droplets. Let's go. At time t1, a representative droplet 502 was released by the fuel material source 71. The direction of movement of the droplet 502 is indicated by a downward arrow. The prepulse radiation 308 collides with the droplet 502. At time t2, the droplet 502 continues to move and begins to adopt the flatter shape caused by the prepulse radiation 308. The following droplet 502'from the fuel material source 71 is shown, which shows the repeatability of the operation of the radiation source device 300 in the actual embodiment.

[0054] At time t3, the lattice radiation 328 with spatial variation 406 collides with the surface of the fuel material in the droplet 502. In the source device having the arrangement shown in FIGS. 3 and 4, the orientation of the interfering beams 328a and 328b of the lattice radiation is such that the spatial variation 406 in the electromagnetic field is periodic or periodic or in the direction to the plane of the drawing of FIG. 5 as a whole. It is configured to be iterative . As shown, the axis is rotated locally so that the spatial variation 406 can be seen purely in the drawing. There are no basic conditions for the spatial variation to be in a particular direction, but if the droplet 502 travels a considerable distance during irradiation with grid radiation, the high intensity band will be aligned with the direction of movement and the grid. It may be convenient for the pattern not to be blurred on the target.

At time t4, the main pulse of laser radiation (second radiation 304) is applied to the target 502. Under the influence of an electromagnetic field with spatial variation 406, one or more properties of the material of the target 502 are altered in the arrangement 504 corresponding to the high intensity portion in the lattice radiation. Modifications can have various forms as described below. Spatically varying changes in one example include spatially varying complex dielectric functions (complex permittivity) resulting from changes in the density of the electron gas within the surface 506 of the target material. This spatially variable dielectric function determines the (complex) index of refraction of the material and affects the interaction of the target material with the second emission 304 of the main laser pulse. This effect can be similar to the effect of a lattice structure etched into a target made of solid material. It is known that the reflectivity of a surface can be altered by a range of effects including, but not limited to, the formation of surface plasmon polaritons described below. In other words, it is not possible to etch the lattice structure onto the target in the case of liquid fuel droplets, but the provision of an electromagnetic field with a suitable spatial distribution of energy across the target alters the optical properties of the target.

At time t5, the second emission 304 caused the target 502 to completely or partially form a plasma 508 emitting the desired first emission 302. For use in the lithography equipment of FIG. 2, the target material can be selected such that the plasma emits EUV radiation in the frequency band, eg, 5-20 nm. Adjusting the spatial variation of the optical properties of the target to achieve a decrease in reflection and an increase in absorption of the second radiation makes it possible to increase the conversion efficiency of the LPP source. There are no basic conditions for the spatial variation to be periodic, to have a fixed spatial frequency, or to have only a single spatial frequency.

[0057] For simplicity of illustration and description, various events in the operation of the source device 300 have been shown to occur at individual time points t1 to t5. In practice, any of these time points may be simultaneous or overlap with one or more of the other time points. For example, in principle, spatial variation can be given to the prepulse radiation 308 or even before the prepulse radiation. However, in practice, it can be difficult to ensure that the applied changes persist in the material until the point of irradiation of the main pulse emission 304 and / or maintain or achieve the desired spacing. .. Rather, time points t3, t4 and / or t5 may be combined or overlapped. For example, the grid radiation 328 may be irradiated at the same time as the main pulse radiation 304, or may be irradiated shortly before the main pulse radiation 304 and time may overlap so that it is maintained during the main pulse radiation 304. In principle, the prepulse radiation 308 is optional. Irradiation of the third radiation 328 according to the present disclosure may be used in combination with various techniques known in the field of LPP sources, and the use of prepulses is a conventional means for enhancing plasma generation and efficiency.

[0058] To summarize the above description, if the obtained electric field strength is sufficiently large, the spatial variation strength in the electric field generated by the third radiation is the space of the complex dielectric function (eg, refractive index) of the fuel material. It leads to the target modulation. This modulation can occur through a variety of mechanisms. One such mechanism is to cause a surface plasmon polariton mode, which requires a particular geometry. This is because, in theory, there is only one suitable wave vector value to succeed. The mathematical derivation of surface plasmon polariton wave vectors is, for example, "Plasmonics: Fundamentals and Applications" in the Maier book by S.A. Maier, Springer Business & Science Media, LLC (2007), 2. It is described in Section 2, Chapters 1-3. In practice, this means that the spatial periodicity of the modulation, the wavelength of the main pulse and its angle of incidence must be coordinated with the dielectric properties of the target material to accurately excite this wavelength. The adjustment of the angle θ shown in FIG. 4 is a practical method for realizing this. Adjustment of the lattice emission wavelength and the angle of incidence is another mechanism. Some options and studies for achieving surface plasmon polariton excitation are shown in FIGS. 6 and 7.

[0059] First, referring to FIG. 6, an embodiment in which the lattice radiation 328 and the main pulse radiation 304 have the same wavelength can be considered. This can be, for example, a result conveniently obtained from the same source, in the same way that prepulse radiation is often derived from the same source as the main pulse radiation. The grid pattern of the modified 504, periodically spaced along the surface 506 of the fuel material, is established, for example, by altering the density of the electron gas in the metallic fuel material. The periodicity of the lattice pattern is practically represented by the wave number (spatial frequency value) which is the reciprocal of the period p shown in the drawing. The main pulse emission 304 collides with the surface 506 at an angle so that the total wave vector component and lattice wavenumber of the main pulse emission along the surface coincides with the surface plasmon polariton excited state. Plasmon propagate to the right, as indicated by arrow 602.

Using lattice radiation of the same wavelength as the main pulse radiation, the shortest lattice period that can be made by one of ordinary skill in the art is half the wavelength (it is impractical with a lattice pulse that collides with the target surface at the shear incident angle). Case). In that case, the main pulse must be incident at a tilt angle α in order for the lattice spatial period p to coincide with the surface plasmon polariton excited state, in which case the main pulse itself is large enough along the target surface. A wave vector component is given to excite the plasmon. In other words, the angle of incidence of the main radiation is constrained by the requirement to excite surface plasmons.

[0061] FIG. 7 shows some variants that are useful when the lattice radiation has a shorter wavelength than the main pulse radiation. Referring to FIG. 7 (a), when the wavelength of the lattice radiation is sufficiently short and the normal incident main pulse (α = 0), the lattice pattern has a spatial period that exactly matches the surface plasmon polariton excited state. It can be produced with p. In such a configuration, plasmons can be excited in both directions along the surface indicated by arrows 604,606.

[0062] In FIG. 7 (b), a larger lattice space period (similar to that shown in FIG. 6) is obtained by changing the angle θ to a smaller value. In order to excite the plasmon 608 in the same direction as in FIG. 6, the non-normal incident angle α is required again for the main pulse radiation 304. By using lattice radiation with shorter wavelengths, the angle θ between the lattice pulses becomes smaller. This results in a more compact configuration of the components of the source device.

[0063] In FIG. 7 (c), the lattice radiation has a shorter wavelength and a wider angle θ. In this case, the reciprocal space period is very short, and using the gradient incident main pulse 304, the surface plasmon polaritons can be excited in the direction 610 opposite to the direction shown in FIGS. 6 and 7 (b). This configuration may be desirable because the short lattice spatial period eliminates its own diffraction. If the reciprocal space period p is shorter than the main pulse wavelength divided by N (N is a positive integer), then N-th and -N-th order diffraction orders cannot exist. Diffracted radiation, as well as reflected radiation, represents an effective loss in the absorption and generation of EUV radiation. Therefore, removing the diffraction order is another way to increase the conversion efficiency.

[0064] The examples shown in FIGS. 6 and 7 are not the only ones possible, and the techniques disclosed herein may be applied in various arrangements and other parameters of lattice pitch and spatial variation. Gives system designers extra flexibility in deciding. There is also an embodiment in which the lattice pulses are not symmetrically arranged on both sides of the normal with respect to the target surface. For targets containing mist or vapor of fuel material through which light propagates deeper, one of ordinary skill in the art may utilize the 3-D relationship under the target surface. For the two beams 328a and 328b where the mist is the target, the grid "lines" can extend deeper into the mist to form a set of excited region planes. This can have the advantage that the main pulse emission 304 can be further guided to the mist if the plane is parallel to the main pulse propagation direction. By having two beams propagating in opposite directions with respect to each coordinate x, y and z, a lattice 3-D optical equivalent, a so-called optical lattice, can also be made. An example of this can be found in the "Optical Lattices and Mott insulator" by the Austrian Academy of Sciences, Innsbruck, Austria (https://www.uibk.ac.at/exphys/ultracold/projects/rubidium/mott#insulator/ See). Such a 3 used to create a corresponding 3-D lattice consisting of an excited / non-excited fuel material (excited if all beams interfere constructively and not if they interfere destructively). -D Optical lattices act like photonic crystals and can also capture light. Six laser beams are required to form a 3-D lattice, while four laser beams can form a 2-D lattice. When using two beams, and assuming that these two beams penetrate deep enough into the mist, this is equivalent to a 1D lattice, which is a set of planes as described above.

[0065] FIGS. 8, 9 and 10 are exemplary timing diagrams showing some different options for the relative timing (and thus the X position) of the various events shown in FIG. 5 in a fairly schematic manner. In each of these figures, the three graphs show the relative timing of the prepulse radiation PP, the grid radiation GP and the main pulse MP. A common time dimension is shown along the horizontal axis of each graph, rather than at a specific scale. The vertical axis is not proportional to the actual size. In each graph, time points t1, t3 and t4 are displayed, corresponding to the time points shown in FIG. 5 during the processing of the fuel droplet 502. In FIG. 8, time point t1'is shown and represents the beginning of the next pulse sequence processing the next fuel droplet 502'.

[0066] In FIG. 8, the timing executed by the controller 316 is substantially the same as that shown in FIG. That is, the pre-pulse radiation, the grid radiation, and the main pulse radiation each arrive at individual time intervals labeled t1, t3, and t14, respectively. In this case, the effect of the lattice emission is assumed to remain longer than the duration of the lattice emission pulse, whereby the spatial modulation of the target characteristics remains when the main pulse reaches time t4.

[0067] FIG. 9 shows another timing similar to that shown in FIG. 8, except that the lattice radiation has a duration extending from before the time t3 at which the main pulse starts to through the duration of the main pulse. This ensures that the spatial modulation of the target characteristics persists during the main pulse period.

Finally, FIG. 10 shows an embodiment in which lattice radiation is continuously and effectively present to ensure that spatial modulation of target characteristics persists during the impulse period. It is understood that many variations to these timing schemes are possible and detailed design is required to achieve optimum performance. Multiple beams of lattice radiation with varying spatial variations may be applied. For example, a grid pattern that expands continuously or in stages while the target expands in response to irradiation with prepulse radiation may be applied to the target with the appropriate configuration of the grid radiation.

[0069] With reference to FIG. 11, this figure shows how a spatially variable intensity distribution can be created without necessarily using two or more coherent beams of lattice radiation. As shown in FIG. 11 (a), the lattice emission 928 is generated from a single beam of source emission 928'provided by a single laser 930 using a spatial light modulator (SLM) 934. According to the numbering in FIG. 4, the spatial light modulator converts the plane wave plane 904 of the source radiation 928'to an electromagnetic field with an optional energy distribution with multiple peaks and valleys across the target. The drawings schematically show the corresponding spatial variation 906 colliding with the target material droplet 902. Of course, other optical elements such as a focus configuration may be provided.

[0070] Spatial light modulators 934 may be fixed (ie, reflective or transmissive devices with a pattern of opaque or phase-shifted portions). Alternatively, the SLM934 may be programmable, eg, a transmissive liquid crystal array or a reflective micromirror array. Both types of SLM are in fact well known. Apart from the possibility of appropriately changing the distribution 906 of the third radiation using the programmable SLM, the SLM allows more arbitrary patterns to be generated.

[0071] In FIG. 11 (b), a simple one-dimensional grid pattern is formed, similar to that shown in FIG. 4 (b). In FIG. 11 (c), the two-dimensional lattice pattern is shown as another example. If the main pulse emission, which is often the case, is linear deflection, the 2D lattice pattern is actually less attractive. In that case, a one-dimensional lattice properly oriented with respect to the polarization direction of the main pulse radiation can be expected to optimize the coupling of the main pulse radiation to the target material. Incidentally, such a two-dimensional lattice pattern can be generated by using a large number of interference beams similar to the pair of beams 328a and 328b. As already mentioned above, patterns with spatially variable pitches and three-dimensional patterns can also be defined. Some types of patterns can be more easily defined using SLM than a pair of multiple beams.

[0072] In the case of programmable SLM934, additional options are possible. The SLM934 may be under the control of, for example, the same controller 916 that controls the third radiation laser 930, the main pulsed laser and the prepulse laser. In the first embodiment, the fine adjustment of the spatial intensity distribution 906 can be performed in real time by using, for example, feedback of conversion efficiency, reflected light, and the like. For example, the grid pitch may vary, but of course more elaborate adjustments may be made. The focal plane of the grid pattern can be adjusted using SLM while potentially eliminating the adjustable focus configuration. In such an example, variations in spatial intensity distribution can be modulated over time during interaction with a series of targets to optimize instrument performance with one or more parameters.

[0073] If the SLM modifies the grid pattern on a sufficiently short timescale, one of ordinary skill in the art will modify the device to modulate the spatial variation of the third radiation over time while interacting with a single target. It can also be configured. By varying the pattern projected during the passage of the lattice generation pulse, one of ordinary skill in the art can adapt the intensity distribution to, for example, the developing dielectric function of the target material. This dielectric function changes over time due to heating, evaporation and plasma formation. As a result, the effect of the applied intensity distribution fluctuates and the fixed intensity distribution is not always optimal. If desired, an additional probe laser may be provided to measure real-time evoked changes in the target material and use these measurements to provide feedback to the SLM.

[0074] To summarize the above example, the spatially variable intensity distribution in the electromagnetic field generated by lattice radiation is designed to spatially modulate one or more properties of the target material. If the excitation is light, the modulation can be caused by an intensity-dependent change in the occupied spectrum of conduction band electrons. If the excitation was more active, there could be local plasma formation or ablation of the material. The expected end result is the modulation of a portion of the physical (space-localized non-thermal electron distribution) surface (the band of plasma that forms the surface undulations or the ablation that causes it) or the electrical (spatial localized non-thermal electron distribution). Is. In all cases, the effective result is the spatial variation of the complex dielectric function over the target. In general, but not necessarily, this can be an effective index of refraction variation of the target. This is because the refractive index is simply a real component of the complex refractive index determined by the dielectric function (complex permittivity).

[0075] Given the cyclically varying index of refraction, the surface of the target can act like a grid. The periodicity of this lattice, the angle of incidence of the main pulse, its wavelength and the dielectric properties of the target (determined by the angle of incidence of the lattice radiating beam and its wavelength) excite the surface plasmon polaritons on the surface when properly coordinated with each other. It is possible to make it. These are charge density waves with a wave vector directed along a surface that takes energy from the main pulse. The excitation of these surface plasmon polaritons dissipates their energy into the material, with the substantial result of increased overall absorption of the main pulse in the absence of lattice pulses.

Excitation of surface plasmon polaritons is not the only anticipation phenomenon that can occur due to changes in the dielectric function within the metal target. A number of different phenomena may be utilized, either alone or in combination with others. The spatially periodic differential dielectric function formed by the lattice radiation makes it possible to establish a waveguide mode in which the main pulse can be coupled under the correct situation. The transfer of energy from the main pulse to the waveguide mode traveling along the surface can lead to increased absorption. Because the electric field always travels a finite distance to the metal, thereby transferring energy to the metal or electrons in the plasma. This energy is then finally dissipated as heat and contributes to the desired enhanced plasma generation.

[0077] FIG. 12 schematically shows the form of an inspection device that can be used for metrology of very small features. The EUV inspection device 1200 is provided to measure the characteristics of the metrology target T formed on the substrate W. The target may be, for example, a structure formed by lithography using the lithography apparatus of FIG. The various hardware components are schematically shown and detailed and varied in detail by U.S. Patent Application Publication No. 2016282282, which is incorporated herein by reference. In short, the source 1230 provides radiation to the lighting system 1232. According to the principles of the present disclosure, the radiation source 1230 is an LPP source of the type described above with reference to any of FIGS. 3-11.

The illumination system 1232 provides an EUV emission beam represented by a ray 1204 that forms a focused irradiation spot on the target T. The radiation reflected by the target T and the substrate W is split into spectra 1210 of lines of intersection of various wavelengths before colliding with the detector 1213. The detector 1213 may be, for example, a CCD (charge coupled device) image sensor. The lighting system 1232 also provides a reference spectrum 1220 to the detector 1214. The components 1212, 1213, etc. may be considered as the detection system 1233 for convenience.

[0079] The substrate W in this example is installed on a movable support having a positioning system 1234 so that the incident angle α of the light beam 1204 is adjusted. To capture the reflected rays 1208, the detection system 1233 is provided with an additional movable support 1236, which moves through an angle 2α with respect to the fixed lighting system or through an angle α with respect to the substrate. Further actuators are provided to carry each target T to a position where the radiation focus spot S is located (not shown).

[0080] Processor 1240 receives signals from detectors 1213 and 1214. In particular, the signal ST from the detector 1213 represents the target spectrum and the signal SR from the detector 1214 represents the reference spectrum. Processor 1240 includes the reflection spectrum of the target normalized to variations in the source spectrum by subtracting the reference spectrum from the target spectrum. The resulting reflection spectrum for one or more angles of incidence is used by the processor to calculate measurements of target characteristics, such as critical dimension (CD) or overlays.

[0081] Aspects of the invention are described below with reference to the following provisions.
Clause 1: A method of producing the first radiation in the first frequency band, wherein the second radiation in the second frequency band is guided by the target to cause the generation of the first radiation, wherein the method is described above. Further comprising delivering a third radiation to the target before and / or in between the delivery of the second radiation, the third radiation is an electromagnetic field having a spatial distribution of energy with numerous peaks and valleys across the target. A method of generating a spatial variation corresponding to the characteristics of the target.
Clause 2: The method of Clause 1, wherein the spatial distribution of the energy is periodic in one or more directions.
Clause 3: The method of Clause 1 or 2, wherein the spatial variation in the property of the target comprises a variation in the effective index of refraction over the target.
[0085] Clause 4: The method of any of Clauses 1-3, wherein the variation in the property of the target comprises a variation in the dielectric function of the electron gas in the fuel material of the target across the target.
Clause 5: The method of any of Clauses 1-4, wherein the variation in the properties of the target comprises a variation in the density of the fuel material of the target across the target.
Clause 6: The method of Clause 5, wherein the variation in the density of the fuel material results from at least a partial ablation of the fuel material over the target.
Clause 7: The method of any of Clauses 1-6, wherein the target comprises a liquid metal droplet when the third radiation is delivered.
Clause 8: The method of any of Clauses 1-7, wherein the target contains at least a partial liquid metal mist when the third radiation is delivered.
Clause 9: The method of any of Clauses 1-8, wherein the target comprises at least a partial plasma after the interaction with the third radiation.
Clause 10: The method of any of Clauses 1-9, wherein a particular amount of fuel material is irradiated with prepulse radiation to form the target prior to delivery of the third radiation.
Clause 11: The method of Clause 10, wherein the fuel material has the form of a liquid metal droplet when the prepulse radiation is delivered.
Clause 12: The method of clause 11 wherein the target comprises a flat droplet or white cloud of fuel material when the third radiation is delivered.
[0094] Clause 13: The electromagnetic field having the spatial distribution of the energy over the target is described in any of Clauses 1-12, which is generated by interfering with two or more beams of the third radiation. Device.
Clause 14: Clause 1-13, wherein the electromagnetic field having a spatial distribution of the energy over the target is generated by interaction with a spatial light modulator by one or more beams of the third radiation. The method described in either.
Clause 15: The method of any of Clauses 1-14, wherein the spatial distribution of said energy in the electromagnetic field is modulated over time during interaction with one target.
Clause 16: The spatial distribution of said energy in the electromagnetic field is modulated over time during interaction with a series of targets to optimize the performance of the source with one or more parameters. The method according to any one of 15.
Clause 17: The spatial variation in the property of the target results in a surface plasmon polariton excited state of the surface of the fuel material in the target with respect to a given wavelength, polarization and angle of incidence of the second radiation. The method of any of clauses 1-16 to be adjusted.
Clause 18: The method of Clause 17, wherein the angle of incidence of the second radiation is perpendicular to the surface of the fuel material.
[0100] Clause 19: The method of any of Clauses 1-18, wherein the third radiation has a wavelength shorter than the wavelength of the second radiation.
[0101] Clause 20: The method of Clause 19, wherein the second radiation has a wavelength of about 10 microns and the third radiation has a wavelength less than 2 microns.
[0102] Clause 21: The method of any of Clauses 1-20, wherein the first radiation has a wavelength in the range of 1 nm to 100 nm.
[0103] Clause 22: The method of Clause 21, wherein the first radiation has a wavelength in the range of 5 nm to 20 nm.
[0104] Clause 23: A method of manufacturing a device, wherein the pattern is applied to the substrate using the radiation of the first wavelength produced by the method according to any of clauses 1-22 to manufacture the device. how to.
[0105] Clause 24: A method of determining the properties of a structure, wherein the structure is illuminated with radiation of a first wavelength produced by the method according to any of Clauses 1-22. A method of determining the properties of a structure in which the radiation is collected after the interaction of.

Conclusion
[ 0106 ] In conclusion, the present disclosure provides a source device and method capable of producing EUV radiation or other radiation with a desired wavelength from a plasma with improved control of reflection and absorption properties. Efficiency can be improved and / or the problem of re-reflection to the laser device can be avoided or mitigated. The improved source device may be included in a lithography device, an inspection device, or any optical device that uses radiation in the first wavelength band. For certain commercial applications, EUV radiation can be produced with improved efficiency, eg, in the range of 5-20 nm.

[ 0107 ] The terms "light", "radiation" and "beam" as used herein are ultraviolet (UV) (eg, having wavelengths between 365 nm and 126 nm or wavelengths of approximately these values), and extremes. It includes all types of electromagnetic radiation, including ultraviolet (EUV) (eg, having wavelengths in the range of 1-100 nm or 5-20 nm). Lithography and inspection equipment can use any of these wavelengths as well as fine particle beams such as ion and electron beams.

[ 0108 ] The term "lens" can, in some contexts, refer to any one or a combination of various types of optical components, including refraction, reflection, magnetic, electromagnetic, and electrostatic optical components. ..

[ 0109 ] The breadth and scope of the invention is not limited by any of the exemplary embodiments described above, but shall be defined solely by the appended claims and their equivalents.

Claims (15)

A device for providing the first radiation in the first frequency band, wherein the device is
A system configured to guide a second radiation in a second frequency band to a target to cause the generation of the first radiation, wherein the third radiation is delivered before and / or during the transmission of the second radiation. Configured to guide to the target, the third radiation is such that it creates an electromagnetic field with a spatial distribution of energy containing numerous peaks and valleys across the target, causing spatial variation corresponding to the characteristics of the target. Sent to, including the system,
The system is configured to guide one or more beams of the third radiation through a spatial light modulator to generate the electromagnetic field.
Device. A device for providing the first radiation in the first frequency band, wherein the device is
A system configured to guide a second radiation in a second frequency band to a target to cause the generation of the first radiation, wherein the third radiation is delivered before and / or during the transmission of the second radiation. Configured to guide to the target, the third radiation is such that it creates an electromagnetic field with a spatial distribution of energy containing numerous peaks and valleys across the target, causing spatial variation corresponding to the characteristics of the target. Sent to, including the system,
The system is capable of operating to modulate the spatial distribution of the energy of the electromagnetic field over time during interaction with one target.
Device. A device for providing the first radiation in the first frequency band, wherein the device is
A system configured to guide a second radiation in a second frequency band to a target to cause the generation of the first radiation, wherein the third radiation is delivered before and / or during the transmission of the second radiation. Configured to guide to the target, the third radiation is such that it creates an electromagnetic field with a spatial distribution of energy containing numerous peaks and valleys across the target, causing spatial variation corresponding to the characteristics of the target. Sent to, including the system,
The system can operate to modulate the spatial distribution of the energy of the electromagnetic field over time during interaction with a series of targets to optimize the performance of the device with one or more parameters.
Device. A device for providing the first radiation in the first frequency band, wherein the device is
A system configured to guide a second radiation in a second frequency band to a target to cause the generation of the first radiation, wherein the third radiation is delivered before and / or during the transmission of the second radiation. Configured to guide to the target, the third radiation is such that it creates an electromagnetic field with a spatial distribution of energy containing numerous peaks and valleys across the target, causing spatial variation corresponding to the characteristics of the target. Sent to, including the system,
The system adjusts the spatial variation in the characteristics of the target to the surface plasmon polariton excited state of the fuel material surface of the target for a given wavelength, polarization and angle of incidence of the second radiation. It is operational,
Device. A device for providing the first radiation in the first frequency band, wherein the device is
A system configured to guide a second radiation in a second frequency band to a target to cause the generation of the first radiation, wherein the third radiation is delivered before and / or during the transmission of the second radiation. Configured to guide to the target, the third radiation is such that it creates an electromagnetic field with a spatial distribution of energy containing numerous peaks and valleys across the target, causing spatial variation corresponding to the characteristics of the target. Sent to, including the system,
The third radiation has a wavelength shorter than the wavelength of the second radiation.
Device. One of claims 1-5 , wherein the system is further configured to irradiate a particular amount of fuel material irradiated with prepulse radiation to form the target prior to delivery of the third radiation. The device described in. 6. The apparatus of claim 6 , further comprising a target material source for providing the fuel material in the form of liquid metal droplets when the prepulse radiation is delivered. The apparatus according to any one of claims 1 to 7 , wherein the system is configured to emit two or more beams of the third radiation that interfere with each other to generate the electromagnetic field. The device of claim 4 , wherein the angle of incidence of the second radiation is perpendicular to the surface of the fuel material. The apparatus of claim 5 , wherein the second emission has a wavelength of about 10 microns and the third emission has a wavelength smaller than 2 microns. The apparatus according to any one of claims 1 to 10 , wherein the first radiation has a wavelength in the range of 1 nm to 100 nm. 11. The apparatus of claim 11 , wherein the first radiation has a wavelength in the range of 5 nm to 20 nm. An EUV optical device comprising a radiation source and an EUV optical system, wherein the radiation source includes the device according to claim 11 or 12 , wherein the EUV optical system receives the first radiation from the radiation source. EUV optics to be placed. 13. A lithography apparatus comprising the EUV optical apparatus according to claim 13 , wherein the EUV optical system includes a projection system for applying a pattern to a substrate using the first radiation from the radiation source. .. 13. The inspection device comprising the EUV optical device according to claim 13 , wherein the EUV optical system guides the first radiation from the radiation source to the structure of interest and after interaction with the structure, said. An inspection device that includes a lighting system for collecting the first radiation.

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