System and method for plasma source with lamphouse correction

Abstract

To provide a plasma light source with lamp house correction.SOLUTION: A system may include a pump source configured to generate pump illumination. The pump illumination may be directed, by an elliptical reflector element, to a volume of gas contained within a plasma lamp to generate a plasma. The plasma may be configured to generate broadband illumination. The system may also include a correction plate and / or an aspherical elliptical reflector element configured to alter the pump illumination and correct aberrations introduced by the plasma lamp. The system may also include an additional aspherical correction plate configured to alter the broadband illumination and correct aberrations introduced by optical elements of the system.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates generally to plasma-based light sources, and more particularly to plasma-based light sources with lamphouse aberration correction. [Background technology]

[0002] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62 / 712,391, filed July 31, 2018, entitled "PLASMA SOURCE LAMP HOUSE CORRECTION METHOD," with Shiyu Zhang, Mark Shi Wang, and Ilya Bezel as inventors, the entire contents of which are incorporated herein by reference.

[0003] As the demand for integrated circuits with ever-smaller device features continues to increase, there is an ever-increasing need for improved illumination sources to be used in the inspection of these ever-shrinking devices. One such illumination source includes a laser-sustained plasma (LSP) source. Laser-sustained plasma light sources are capable of producing high-power broadband illumination. Laser-sustained plasma light sources operate by focusing laser radiation into a gas volume contained within a plasma lamp, exciting a gas, such as argon or xenon, into a plasma state capable of emitting broadband illumination. This effect is commonly referred to as "pumping" the plasma.

[0004] The effectiveness of laser-sustained light sources is based, at least in part, on their ability to generate plasma in a tight, compact, and precisely known location. However, optical components within laser-sustained plasma light sources, including the plasma lamp itself, can distort the pump laser radiation, thereby requiring increased pumping power and leading to thermal management issues. Distortion of the pump laser radiation can distort the focus of the pump source, thereby increasing the plasma size, increasing the system etendue, and reducing throughput. Furthermore, optical components within laser-sustained plasma light sources can also introduce aberrations into the illumination generated by the plasma, making it difficult to collect the generated illumination and thereby reducing throughput. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2015 / 0163893 [Patent Document 2] U.S. Patent Application Publication No. 2017 / 0278694 [Patent Document 3] U.S. Patent Application Publication No. 2006 / 0238856 Summary of the Invention [Problem to be solved by the invention]

[0006] It would therefore be desirable to provide a system and method that addresses one or more of the above-identified deficiencies. [Means for solving the problem]

[0007] A system is disclosed in accordance with one or more embodiments of the present disclosure. In one embodiment, the system includes a pump source configured to generate pump illumination. In another embodiment, the system includes a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination to compensate for one or more aberrations of the pump illumination introduced by one or more optical elements of the system. In another embodiment, the system includes a reflector element configured to receive the pump illumination and direct the pump illumination toward a gas volume contained within a plasma lamp, where the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination.

[0008] A system is disclosed in accordance with one or more embodiments of the present disclosure. In one embodiment, the system includes a broadband illumination source. The broadband illumination source may include a pump source configured to generate pump illumination, a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination, and a reflector element configured to receive the pump illumination and direct the pump illumination toward a gas volume contained within a plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to generate the broadband illumination. In another embodiment, the system includes a detector assembly. In another embodiment, the system includes a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination toward a sample. In another embodiment, the set of characterization optics is further configured to direct radiation from the sample toward the detector assembly.

[0009] A system is disclosed in accordance with one or more embodiments of the present disclosure. In one embodiment, the system includes a pump source configured to generate pump illumination. In another embodiment, the system includes a first corrector configured to receive the pump illumination and modify one or more characteristics of the pump illumination. In another embodiment, the system includes a reflector element configured to receive the pump illumination and direct the pump illumination toward a gas volume contained within a plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination. In another embodiment, the system includes a second corrector configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, where the second corrector includes an aspheric corrector.

[0010] A system is disclosed in accordance with one or more embodiments of the present disclosure. In one embodiment, the system includes a broadband illumination source. In another embodiment, the broadband illumination source includes a pump source configured to generate pump illumination, a first corrector plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination, and a reflector element configured to receive the pump illumination and direct the pump illumination toward a gas volume contained within a plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to generate the broadband illumination. In another embodiment, the broadband illumination source includes a second corrector plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination. In another embodiment, the second corrector plate includes an aspheric corrector plate. In another embodiment, the system includes a detector assembly. In another embodiment, the system includes a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination toward a sample, the set of characterization optics further configured to direct radiation from the sample toward the detector assembly.

[0011] A method is disclosed in accordance with one or more embodiments of the present disclosure. In one embodiment, the method includes generating pump illumination. In another embodiment, the method includes correcting the pump illumination using a first corrector plate. In another embodiment, the method includes collecting the pump illumination using a reflector element and directing the pump illumination toward a gas volume contained within a plasma lamp. In another embodiment, the method includes generating a plasma within a gas volume contained within the plasma lamp. In another embodiment, the method includes generating broadband illumination using the plasma. In another embodiment, the method includes correcting one or more aberrations of the broadband illumination using a second corrector plate.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the summary, serve to explain the principles of the invention. [Brief explanation of the drawings]

[0013] Many advantages of the present disclosure may be better understood by those skilled in the art by reference to the following drawings. [Figure 1A] 1 illustrates a plasma source with a lamphouse correction system in accordance with one or more embodiments of the present disclosure. [Figure 1B] 1 illustrates a plasma source with a lamphouse correction system in accordance with one or more embodiments of the present disclosure. [Figure 2A] 10 illustrates a pumping focal profile cross section near an elliptical reflector in a system with a cylindrical plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 2B] 10 illustrates a pumping focal profile cross section near an elliptical reflector in a system with a cylindrical plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 3A] 1 shows a cross-section of a pumping thermal profile at the focus of an elliptical reflector in a system with a cylindrical plasma lamp, in accordance with one or more embodiments of the present disclosure. [Figure 3B] 1 shows a cross-section of a pumping thermal profile at the focus of an elliptical reflector in a system with a cylindrical plasma lamp, in accordance with one or more embodiments of the present disclosure. [Figure 4A] 1 shows a collection thermal profile cross section at an elliptical reflector focus in a system with a cylindrical plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 4B] 10 shows a cross section of a collected thermal profile at an elliptical reflector focus in a system with a cylindrical plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 5A] 10 illustrates a pumping focal profile cross section at an elliptical reflector focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 5B] 10 illustrates a pumping focal profile cross section at an elliptical reflector focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 6] 1 shows a surface profile graph of an aspheric corrector plate in accordance with one or more embodiments of the present disclosure. [Figure 7A] 10 illustrates a pumping focal profile cross section at an elliptical reflector focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 7B] 10 illustrates a pumping focal profile cross section at an elliptical reflector focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 8] 1 shows a surface profile graph of an aspheric corrector plate in accordance with one or more embodiments of the present disclosure. [Figure 9A] 1 illustrates a collection focus profile cross section at the collection focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 9B]10 illustrates a collection focus profile cross section at a collection focus in a system with a prolate spheroid shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 10A] 10 illustrates a collection focus profile cross section at a collection focus in a system with a prolate spheroid shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 10B] 10 illustrates a collection focus profile cross section at a collection focus in a system with a prolate spheroid shaped plasma lamp in accordance with one or more embodiments of the present disclosure. [Figure 11] 1 shows a simplified schematic diagram of an optical characterization system implementing a plasma source with a lamphouse correction system in accordance with one or more embodiments of the present disclosure. [Figure 12] 1 shows a simplified schematic diagram of an optical characterization system implementing a plasma source with a lamphouse correction system in accordance with one or more embodiments of the present disclosure. [Figure 13] 1 illustrates a flow diagram of a method for correcting errors induced by a plasma source lamphouse in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present disclosure has been particularly shown and described with respect to certain embodiments and specific features thereof. The embodiments described herein are to be construed as illustrative and not restrictive. It will be readily apparent to those skilled in the art that various changes and modifications in form and detail can be made therein without departing from the spirit and scope of the present disclosure.

[0015] Reference will now be made in detail to the subject matter disclosed, which is illustrated in the accompanying drawings.

[0016] 1A-13, a plasma source with a lamphouse correction system and method according to one or more embodiments of the present disclosure is described.

[0017] Embodiments of the present disclosure are directed to systems and methods for correcting errors due to components within a laser-sustained plasma (LSP) light source. In particular, embodiments of the present disclosure are directed to systems and methods for correcting aberrations due to components within an LSP light source, including, but not limited to, compensators, plasma lamps, etc. Additional embodiments of the present disclosure are directed to the use of aspherical corrector plates and / or aspherical reflector elements to modify the pump illumination of the LSP light source to correct for aberrations due to components within the LSP light source. Additional embodiments of the present disclosure are directed to the use of aspherical corrector plates to modify the broadband illumination generated by the plasma of the LSP light source to correct for aberrations due to components within the LSP light source.

[0018] As previously described herein, the optical components of an LSP light source can distort the pump radiation / illumination of the LSP light source. Distortion of the pump radiation / illumination can require additional pumping power to achieve the same throughput, thus leading to thermal management issues. Additionally, distorted pump radiation can distort the focus of the pump radiation, thereby increasing the plasma size, increasing the system etendue, and reducing the system throughput. Furthermore, the optical components within the LSP light source can also introduce aberrations into the broadband illumination generated by the plasma itself, making it difficult to collect the generated illumination, thereby reducing throughput.

[0019] For example, LSP light sources may utilize plasma lamps of different shapes, including, but not limited to, cylindrical plasma lamps, prolate spheroid-shaped plasma lamps (e.g., "football" plasma lamps), etc. These plasma lamp configurations can distort the illumination entering and exiting the plasma lamp. If left uncorrected, these distortions and / or aberrations caused by the plasma lamp and other optical elements can increase the power required by the LSP light source, reduce its effectiveness, and decrease throughput. Accordingly, embodiments of the present disclosure are directed to systems and methods for correcting aberrations caused by the optical components of an LSP light source. Correcting aberrations in an LSP light source can reduce the required pumping power, produce a tighter and brighter plasma focus, and improve collection of illumination generated by the plasma.

[0020] 1A and 1B show a plasma source with a lamphouse correction system 100 in accordance with one or more embodiments of the present disclosure. In general, the system 100 may include a pump source 102, a lamphouse 104, an entrance window 106, a cold mirror 116, a reflector element 110, and an exit window 120.

[0021] FIG. 1A illustrates a plasma source with a lamphouse correction system 100 according to one or more embodiments of the present disclosure. The system 100 may include, but is not limited to, a pump source 102 and a lamphouse 104. The lamphouse 104 may include, but is not limited to, a plasma lamp 112 including an entrance window 106, a corrector plate 108, a reflector element 110, a gas volume configured to generate a plasma 114, a cold mirror 116, an additional corrector plate 118, and an exit window 120. In another embodiment, the system 100 may include one or more optical elements 122 and one or more downstream optical elements 124. Note that unless otherwise stated herein, the described configurations should not be considered limiting. In this regard, the system 100 may include additional / fewer optical elements than those shown and described. For example, the additional corrector plate 118 and the exit window 120 may be combined into a single component, such that the additional corrector plate 118 functions as the exit window.

[0022] In one embodiment, the pump source 102 is configured to generate pump illumination 101 and direct the pump illumination 101 along a pumping path 103. The pump source 102 may include any illumination source configured to pump a plasma known in the art, including, but not limited to, one or more lasers. For example, the pump source 102 may include one or more fiber lasers or any form of electrical energy known in the art. For example, the pump source 102 may include one or more 200 μm fiber lasers. As another example, the pump source 102 may include one or more infrared lasers. Note that for purposes of this disclosure, the terms “pump illumination 101” and “pump radiation 101” may be used interchangeably herein, unless otherwise specified. Additionally, the term “pumping path 103,” and similar terms, may refer to the path that the pump illumination 101 takes from the pump source 102 to the plasma 114. The pump illumination 101 may include illumination / radiation of any wavelength or range of wavelengths known in the art, including, but not limited to, infrared (IR) radiation, near-infrared (NIR) radiation, ultraviolet (UV) radiation, visible radiation, etc.

[0023] In another embodiment, the pump illumination 101 enters the lamphouse 104 through an entrance window 106. The entrance window 106 may include any optical element known in the art for transmitting illumination, including, but not limited to, one or more windows, one or more lenses, one or more ports, etc. In another embodiment, the pump illumination 101 is directed toward a corrector plate 108. The corrector plate 108 may include a cylindrical corrector plate. In one embodiment, the corrector plate 108 is configured to modify one or more characteristics of the pump illumination 101. For example, the corrector plate 108 may be configured to correct one or more aberrations in the pump illumination introduced by optical elements of the system 100.

[0024] In another embodiment, pump illumination 101 is directed toward a reflector element 110. As shown in FIG. 1A, the reflector element 110 may include an elliptical reflector element 110. However, this should not be considered limiting unless described herein, as the elliptical reflector element 110 can take any shape known in the art for directing pump illumination 101 toward a plasma lamp 112. The reflector element 110 can be configured to receive the pump illumination 101 and direct the pump illumination 101 into a gas volume contained within the plasma lamp 112 to generate a plasma 114 within the gas volume. The plasma lamp 112 can take any shape known in the art for containing a gas volume. For example, as shown in FIG. 1A, the plasma lamp 112 can include a cylindrical plasma lamp 112. The cylindrical plasma lamp 112 can include a gas volume containing any gas or mixture of gases known in the art suitable for generating a plasma, including, but not limited to, xenon (Xe), argon (Ar), etc. In one embodiment, the gas volume contained within the cylindrical plasma lamp 112 may be contained at a high pressure. For example, the gas volume within the cylindrical plasma lamp 112 may be at 10 atmospheres.

[0025] As previously described herein, the plasma lamp 112 can distort the pump illumination 101 entering the plasma lamp 112 and / or distort the broadband illumination 107 (e.g., broadband radiation 107) generated by the plasma 114 and exiting the plasma lamp 112. Furthermore, additional optical elements in the system 100 can introduce additional distortions. These distortions can result in one or more aberrations in the broadband illumination 107 generated by the plasma, thereby reducing the effectiveness of the system 100 and decreasing throughput. Aberrations introduced by the plasma lamp 112 and / or additional optical elements in the system 100 can be better understood with reference to FIGS. 2A and 2B.

[0026] 2A and 2B show pumping focal profile cross sections near an elliptical reflector in a system 100 with a cylindrical plasma lamp 112, in accordance with one or more embodiments of the present disclosure. The irradiance of the focal profiles in graphs 200 and 202 is expressed in W / mm 2 The distance is expressed in units of . Graph 200 shows a pumping focal spot profile cross section along the XY plane, as shown in FIG. 2A. Graph 202 shows a pumping focal spot profile cross section along the XZ plane, as shown in FIG. 2B. As seen in FIGS. 2A and 2B, a cylindrical plasma lamp (e.g., cylindrical plasma lamp 112) can introduce a large amount of distortion / aberration near the reflector element 110 (e.g., elliptical reflector element 110). As an example, a 28 μm plasma ball at an elliptical focus can be re-imaged to more than 60 mm at the pumping focal spot. If uncorrected, this level of distortion / aberration can reduce pumping efficiency, reduce the collection efficiency of broadband illumination 107, and decrease throughput.

[0027] Referring again to FIG. 1A , the reflector element 110 (e.g., the elliptical reflector element 110) may be configured to correct one or more aberrations induced by the plasma lamp 112 and / or additional optical elements along the pumping path 103. In one embodiment, the reflector element 110 may include an odd-term aspherical reflector element to minimize and / or reduce aberrations introduced by the plasma lamp 112 and / or additional optical elements. In one embodiment, many odd-order aspherical terms may be added to the reflector element 110 (e.g., the elliptical reflector element 110) to correct aberrations introduced by the plasma lamp 112 (e.g., the cylindrical plasma lamp 112). For example, two odd-order aspherical terms may be added to the reflector element 110. As another example, six odd-order aspherical terms may be added to the reflector element 110. As a further example, 100 odd-order aspherical terms may be added to the reflector element.

[0028] The surface profile of an aspherical reflector element 110 (eg, an aspherical elliptical reflector element 110) may be described by Equation 1:

number

number

[0029] The advantages that may be realized using aspherical reflector element 110 to correct aberrations introduced along pump path 103 can be better understood with reference to FIGS. 3A and 3B.

[0030] 3A and 3B show pumping thermal profile cross-sections at an elliptical reflector focus for a system 100 with a cylindrical plasma lamp 112 in accordance with one or more embodiments of the present disclosure. Graphs 300 and 302 show pumping thermal profile cross-sections for a 28 μm plasma ball at an elliptical reflector focus. Graph 300 (FIG. 3A) shows the thermal profile cross-section for a system without an aspherical reflector element 110, while graph 302 (FIG. 3B) shows the thermal profile cross-section for a system with an aspherical reflector element 110 to correct aberrations along the pumping path 103. Comparing FIGS. 3A and 3B, it can be seen that the aspherical reflector element 110 can correct aberrations introduced by the cylindrical plasma lamp 112 and / or other optical elements along the pumping path 103. In some embodiments, the inclusion of the aspherical reflector element 110 can reduce the pumping thermal profile cross-section by more than 60 times.

[0031] As previously mentioned, the reflector element 110 may focus the pump illumination 101 toward the gas volume contained within the plasma lamp 112 to generate the plasma 114. In another embodiment, the plasma 114 emits broadband illumination 107. The broadband illumination 107 may include illumination / radiation of various wavelengths, including, but not limited to, ultraviolet (UV) radiation, deep ultraviolet (DUV) radiation, vacuum ultraviolet (VUV) radiation, etc. The broadband illumination 107 may be directed by a cold mirror 116. The cold mirror 116 may include any optical element known in the art, including, but not limited to, a beam splitter, a sampler, a filter, etc. In another embodiment, the cold mirror 116 directs the broadband illumination 107 along the collection path 105 to an additional corrector plate 118. Note that, for purposes of this specification, the collection path 105 may be considered as the path of the broadband illumination 107 from the plasma 114 to the downstream optical element 124.

[0032] In another embodiment, the cold mirror 116 directs the broadband illumination 107 to an additional corrector 118. In additional and / or alternative embodiments, the additional corrector 118 may be configured to correct distortions and / or aberrations introduced into the broadband illumination 107 along the collection path 105. In this regard, the additional corrector 118 may include an aspheric corrector 118. For example, the additional corrector 118 may include an odd-term aspheric corrector 118. It is noted herein that the use of an additional corrector 118 in the collection path 105 may improve the correction of the broadband illumination 107 and therefore may increase the throughput and efficiency of the system 100.

[0033] The benefit of the additional corrector plate 118 for correcting distortions and / or aberrations introduced along the collection path 105 can be better understood with reference to Figures 4A and 4B.

[0034] 4A and 4B show thermal profile cross-sections at an elliptical reflector focus in a system 100 with a cylindrical plasma lamp 112 in accordance with one or more embodiments of the present disclosure. Graph 400 in FIG. 4A shows the thermal profile cross-section of a 28 μm plasma disk positioned at the elliptical focus. Similarly, graph 402 in FIG. 4B shows the thermal profile cross-section of a 28 μm plasma ball positioned at the elliptical focus.

[0035] Referring again to FIG. 1A , in another embodiment, the broadband illumination 107 is directed along the collection path 105 to an exit window 120. The exit window 120 may include any optical element configured to allow the broadband illumination 107 to exit the lamphouse 104, including, but not limited to, one or more windows, one or more lenses, one or more ports, etc. In another embodiment, the broadband illumination 107 is directed along the collection path 105 through one or more optical elements 122. The one or more optical elements 122 may include any optical element known in the art, including, but not limited to, one or more color filters, one or more lenses, one or more mirrors, one or more beam splitters, one or more prisms, etc. In another embodiment, the one or more optical elements 122 direct the broadband illumination 107 to one or more downstream optical elements 124. The one or more downstream optical elements 124 may include any optical element known in the art for shaping, collecting, or focusing the characterization illumination 109, including, but not limited to, one or more homogenizers, one or more polarizers, one or more beam shapers, etc. The characterization illumination 109 may be used in any downstream characterization system, including, but not limited to, an imaging system, a metrology system, a spectroscopy system, etc.

[0036] It is noted herein that the order of optical elements arranged along pumping path 103 and / or collection path 105 should not be considered limiting unless otherwise stated herein. For example, after being directed by cold mirror 116, broadband illumination 107 may exit lamphouse 104 through exit window 120 and then interact with additional corrector plate 118. Thus, the order of optical elements in FIG. 1A is provided for illustrative purposes only, unless otherwise stated herein.

[0037] FIG. 1B illustrates a plasma source-lamphouse correction system 100 according to one or more embodiments of the present disclosure. The system 100 may include, but is not limited to, a pump source 102 and a lamphouse 104. The lamphouse 104 may include, but is not limited to, an entrance window 106, a compensator plate 126, a corrector plate 128, a reflector element 110, a plasma lamp 130 (e.g., a prolate spheroid-shaped plasma lamp 130), a cold mirror 116, an additional corrector plate 132, and an exit window 120. In this specification, any description related to FIG. 1A, to the extent applicable, may be considered to apply to FIG. 1B unless otherwise stated herein. Similarly, any description related to FIG. 1B, to the extent applicable, may be considered to apply to FIG. 1A unless otherwise stated herein.

[0038] In one embodiment, as shown in FIG. 1B, the plasma lamp includes a substantially prolate spheroidal plasma lamp 130 (e.g., a substantially "football-shaped" plasma lamp 130). Similar to the cylindrical plasma lamp 112, it is noted herein that the prolate spheroidal plasma lamp 130 may introduce aberrations into the system 100. In a system where the aberrations introduced by the prolate spheroidal plasma lamp 130 are not corrected, the pump laser power may be in the range of approximately 4 to 7 kilowatts (kW). The aberrations introduced by the prolate spheroidal plasma lamp 130 may be better understood with reference to FIG. 5A.

[0039] 5A shows a pump focal profile cross-section at an elliptical reflector focus in a system 100 with a prolate spheroid-shaped plasma lamp 130 in accordance with one or more embodiments of the present disclosure. Graph 500 shown in FIG. 5A shows a pump focal profile cross-section for a 200 μm fiber laser source. As can be seen in FIG. 5A, the prolate spheroid-shaped plasma lamp 130 can introduce significant distortions and / or aberrations into the system 100, which need to be corrected.

[0040] 1B, in one embodiment, system 100 includes compensator 126. It is noted herein that compensator 126, in addition to the plasma lamp (e.g., cylindrical plasma lamp 112, prolate spheroidal plasma lamp 130, etc.), can introduce distortions and / or aberrations into system 100 that need to be corrected.

[0041] In another embodiment, system 100 includes a corrector plate 128. Note that unless otherwise stated herein, discussions regarding corrector plate 108 and additional corrector plate 118 may be deemed to apply to corrector plate 128. In one embodiment, corrector plate 128 includes an aspherical corrector plate 128. Corrector plate 128 (e.g., aspherical corrector plate 128) may be configured to correct one or more aberrations and / or astigmatism introduced by compensator 126, cold mirror 116, plasma lamp (e.g., prolate spheroid-shaped plasma lamp 130), etc. In one embodiment, corrector plate 128 may include a modified cylindrical corrector plate. For example, corrector plate 128 may be formed by adding up to a third-order odd aspherical term to the rear surface of cylindrical corrector plate 108. In another embodiment, corrector 128 may include two separate corrector plates, an odd aspherical collector and a cylindrical collector, configured to correct one or more aberrations and / or astigmatism introduced by compensator 126, cold mirror 116, plasma lamp (e.g., prolate spheroid-shaped plasma lamp 130), etc. In yet another embodiment, corrector 128 may include an anamorphic profile, which combines an odd aspherical term with a cylindrical corrector on a single surface of corrector 128.

[0042] The aspheric profile of corrector plate 128 (eg, aspheric corrector plate 128) can be better understood by referring to FIG.

[0043] 6 illustrates a surface profile graph 600 of an aspheric corrector plate (e.g., aspheric corrector plate 128) in accordance with one or more embodiments of the present disclosure. In one example, curve 602 of graph 600 may illustrate the surface profile of corrector plate 128 (e.g., aspheric corrector plate 128). However, it is noted herein that curve 602 is provided for illustrative purposes only and should not be considered limiting of the scope of the present disclosure unless otherwise stated herein.

[0044] Corrector plate 128 may help correct aberrations and / or astigmatism introduced into system 100 along pumping path 103. To further explain this effect, reference is again made to Figures 5A and 5B.

[0045] 5A and 5B show pump focal profile cross sections at an elliptical reflector focus in a system 100 including a prolate spheroid-shaped plasma lamp 130 in accordance with one or more embodiments of the present disclosure. In particular, graph 500 shown in FIG. 5A shows a pump focal profile cross section of a 200 μm fiber laser source that is not corrected by a corrector plate 128. Conversely, graph 502 shown in FIG. 5B shows a pump focal profile cross section of a 200 μm fiber laser source that is corrected by a corrector plate 128.

[0046] As seen in graph 502, for a compensated 200 μm fiber laser source, the full width at half maximum (FWHM) of the focal profile cross section is approximately 20 μm. In addition, a 200 μm fiber laser source may be capable of providing approximately 4 kW of output power, and thus may be sufficient for use with a wide range of LSP sources, even when compensated using compensation plate 128. Comparing graphs 500 and 502, it can be seen that the compensated focal energy density (e.g., compensated with system 100) may be between 10 and 55 times the uncompensated focal energy density. The level of improvement achieved by system 100 may depend on many factors, including, but not limited to, the type of pump source 102, the manufacturing of the plasma lamp (e.g., cylindrical plasma lamp 112, prolate spheroidal plasma lamp 130, etc.), alignment tolerances, etc.

[0047] 7A and 7B show pump focal profile cross sections at an elliptical reflector focus in a system 100 including a prolate spheroid-shaped plasma lamp 130 in accordance with one or more embodiments of the present disclosure. In particular, graph 700 shown in FIG. 6A shows a pump focal profile cross section of a 600 μm fiber laser source uncorrected by the corrector plate 128. Conversely, graph 702 shown in FIG. 6B shows a pump focal profile cross section of a 600 μm fiber laser source corrected by the corrector plate 128. Comparing graphs 700 and 702, the corrected focal energy density (e.g., corrected by the system 100) is approximately 2.4 times the uncorrected focal energy density, representing an improvement of approximately 140% relative to the 600 μm fiber laser source.

[0048] It is noted herein that the position of the pump source 102 can be adjusted to change the position of the focal point of the pump illumination 101. For example, the tip of the fiber laser can be adjusted along the optical axis to change the position of the plasma 114. For example, moving the tip of the fiber laser about 6.4 mm can move the plasma 114 about 5.5 μm.

[0049] 1B , following the corrector plate 128, the pump illumination 101 may be directed along a pumping path 103 to a reflector element 110 (e.g., an elliptical reflector element 110). The reflector element 110 may be configured to receive the pump illumination 101 and direct the pump illumination 101 toward a gas volume contained within a prolate spheroid-shaped plasma lamp 130 to generate a plasma 114 within the gas volume. In another embodiment, the plasma 114 generates broadband illumination 107, including, but not limited to, ultraviolet (UV) illumination, deep ultraviolet (DUV) illumination, vacuum ultraviolet (VUV) illumination, etc.

[0050] In another embodiment, the cold mirror 116 can direct the broadband illumination 107 along the collection path 105 to an additional corrector plate 132. In additional and / or alternative embodiments, the additional corrector plate 132 can be configured to correct any distortions and / or aberrations introduced into the broadband illumination 107 by optical elements along the collection path 105, including, but not limited to, the prolate spheroid-shaped plasma lamp 130. In this regard, the additional corrector plate 132 can include an aspherical corrector plate 132. For example, the additional corrector plate 132 may include an odd-term aspherical corrector plate 132. It is noted herein that the use of an additional corrector plate 132 in the collection path 105 can improve the correction of the broadband illumination 107 and therefore increase the throughput and efficiency of the system 100.

[0051] It is further noted that, unless otherwise stated herein, discussions related to corrector plate 108, additional corrector plate 118, and corrector plate 128 may be considered to apply to additional corrector plate 132. Accordingly, in one embodiment, odd aspheric terms up to third order may be added to additional corrector plate 132 to correct for aberrations introduced by prolate spheroidal plasma lamp 130. In addition, it is noted herein that the surface profile of additional corrector plate 132 may be described by Equation 1 or Equation 2.

[0052] The advantages of the additional correction plate 132 for correcting distortions and / or aberrations introduced into the system 100, including the prolate spheroid-shaped plasma lamp 130, can be better understood with reference to Figures 8, 9A, and 9B.

[0053] 8 illustrates a surface profile graph 800 of an additional corrector plate 132 (e.g., an aspheric corrector plate 132) in accordance with one or more embodiments of the present disclosure. In one example, curve 802 of graph 800 may illustrate the surface profile of an additional corrector plate 132 (e.g., an aspheric corrector plate 132). However, it is noted that curve 802 is provided herein for illustrative purposes only and should not be considered a limitation on the scope of the present disclosure unless otherwise stated herein.

[0054] 9A and 9B show collection focus profile cross sections at the collection focus in a system 100 including a prolate spheroid-shaped plasma lamp 130, in accordance with one or more embodiments of the present disclosure. Graph 900 shown in FIG. 9A shows the collection focus profile cross section of a 20 μm plasma ball source uncorrected by an aspherical corrector plate 132. Conversely, graph 902 shown in FIG. 9B shows the collection focus profile cross section of a 20 μm plasma ball source corrected by an aspherical corrector plate 132.

[0055] 10A and 10B show collection focus profile cross sections at the collection focus in a system with a prolate spheroid-shaped plasma lamp in accordance with one or more embodiments of the present disclosure. Graph 1000 shown in FIG. 10A shows the collection focus profile cross section for a 200 μm plasma ball source uncorrected by an aspherical corrector plate 132. Conversely, graph 1002 shown in FIG. 10B shows the collection focus profile cross section for a 200 μm plasma ball source corrected by an aspherical corrector plate 132.

[0056] 9A and 9B, as well as FIGS. 10A and 10B, it can be seen that correcting the broadband illumination 107 along the collection path 105 can significantly improve the collection efficiency of the system 100.

[0057] 11 shows a simplified schematic diagram of an optical characterization system 1100 implementing the plasma source lamphouse correction system 100 in accordance with one or more embodiments of the present disclosure. In one embodiment, the system 1100 includes the system 100, an illumination arm 1103, a collection arm 1105, a detector assembly 1114, and a controller 1118 including one or more processors 1120 and memory 1122.

[0058] It is noted herein that system 1100 may include any imaging, inspection, metrology, lithography, or other characterization system known in the art. In this regard, system 1100 may be configured to perform inspection, optical metrology, lithography, and / or any form of imaging on specimen 1107. Specimen 1107 may include any sample known in the art, including, but not limited to, wafers, reticles / photomasks, etc. It is noted that system 1100 may incorporate one or more of the various embodiments of system 100 described throughout this disclosure.

[0059] In one embodiment, the specimen 1107 is positioned on a stage assembly 1112 to facilitate movement of the specimen 1107. The stage assembly 1112 may include any stage assembly 1112 known in the art, including, but not limited to, an XY stage, an R-Theta stage, etc. In another embodiment, the stage assembly 1112 may adjust the height of the specimen 1107 to maintain focus on the specimen 1107 during inspection or imaging.

[0060] In another embodiment, the illumination arm 1103 is configured to direct the characterization illumination 109 from the system 100 onto the specimen 1107. The illumination arm 1103 may include any number and type of optical elements known in the art. In one embodiment, the illumination arm 1103 includes one or more optical elements 1102, a beam splitter 1104, and an objective lens 1106. In this regard, the illumination arm 1103 may be configured to focus the characterization illumination 109 from the system 100 onto the surface of the specimen 1107. The one or more optical elements 1102 may include any optical element or combination of optical elements known in the art, including, but not limited to, one or more mirrors, one or more lenses, one or more polarizers, one or more gratings, one or more filters, one or more beam splitters, etc.

[0061] In another embodiment, the collection arm 1105 is configured to collect light reflected, scattered, diffracted, and / or emitted from the specimen 1107. In another embodiment, the collection arm 1105 may direct and / or focus light from the specimen 1107 onto a sensor 1116 of the detector assembly 1114. It is noted that the sensor 1116 and the detector assembly 1114 may include any sensor and detector assembly known in the art. The sensor 1116 may include, but is not limited to, a charge-coupled device (CCD) detector, a complementary metal-oxide semiconductor (CMOS) detector, a time-delay integration (TDI) detector, a photomultiplier tube (PMT), an avalanche photodiode (APD), or the like. Additionally, the sensor 1116 may include, but is not limited to, a line sensor or an electron-bombarded line sensor.

[0062] In another embodiment, the detector assembly 1114 is communicatively coupled to a controller 1118 that includes one or more processors 1120 and a memory 1122. For example, the one or more processors 1120 can be communicatively coupled to the memory 1122, where the one or more processors 1120 are configured to execute a set of program instructions stored in the memory 1122. In one embodiment, the one or more processors 1120 are configured to analyze an output of the detector assembly 1114. In one embodiment, the set of program instructions are configured to cause the one or more processors 1120 to analyze one or more characteristics of the test strip 1107. In another embodiment, the set of program instructions are configured to cause the one or more processors 1120 to modify one or more characteristics of the system 1100 to maintain focus on the test strip 1107 and / or the sensor 1116. For example, the one or more processors 1120 may be configured to adjust the objective lens 1106 or one or more optical elements 1102 to focus characterization illumination 109 from the system 100 onto the surface of the specimen 1107. As another example, the one or more processors 1120 may be configured to adjust the objective lens 1106 and / or one or more optical elements 1110 to collect illumination from the surface of the specimen 1107 and focus the collected illumination onto the sensor 1116.

[0063] It is noted that system 1100 may be configured in any optical configuration known in the art, including but not limited to dark-field configurations, bright-field orientations, and the like.

[0064] As used herein, one or more components of system 1100 may be communicatively coupled to various other components of system 1100 in any manner known in the art. For example, system 1100, detector assembly 1114, controller 1118, and one or more processors 1120 may be communicatively coupled to each other and to other components via wires (e.g., copper wire, fiber optic cable, etc.) or wireless connections (e.g., RF coupling, IR coupling, data network communication (e.g., WiFi, WiMax, Bluetooth, etc.)).

[0065] Figure 12 shows a simplified schematic diagram of an optical characterization system 1200 arranged in a reflectometry and / or ellipsometry configuration, in accordance with one or more embodiments of the present disclosure. Note that the various embodiments and components described with respect to Figure 11 may be construed to cover the system of Figure 12. System 1200 may include any type of metrology system known in the art.

[0066] In one embodiment, system 1200 includes system 100 , illumination arm 1116 , collection arm 1118 , detector assembly 1228 , and controller 1118 including one or more processors 1120 and memory 1122 .

[0067] In this embodiment, characterization illumination 109 from system 100 is directed toward specimen 1107 via illumination arm 1216. In another embodiment, system 1200 collects radiation emitted from the sample via collection arm 1218. Illumination arm path 1216 may include one or more beam conditioning components 1220 suitable for modifying and / or conditioning characterization illumination 190. For example, one or more beam conditioning components 1220 may include, but are not limited to, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, or one or more lenses.

[0068] In another embodiment, the illumination arm 1216 may utilize a first focusing element 1222 to focus and / or direct the characterization illumination 109 onto the specimen 1107 disposed on the sample stage 1112. In another embodiment, the collection arm 1218 may include a second focusing element 1226 to collect radiation from the specimen 1107.

[0069] In another embodiment, the detector assembly 1228 detects the signal from the specimen 1107 to the collection arm 12 18. For example, detector assembly 1228 may receive radiation reflected or scattered (e.g., via specular reflection, diffuse reflection, etc.) from specimen 1107. As another example, detector assembly 1228 may receive radiation generated by specimen 1107 (e.g., luminescence associated with absorption of the beam, etc.). It is noted that detector assembly 1228 may include any sensor and detector assembly known in the art. Sensors may include, but are not limited to, CCD detectors, CMOS detectors, TDI detectors, PMTs, APDs, etc.

[0070] The collection arm 1218 may further include any number of collection beam conditioning elements 1230 to direct and / or modify the illumination collected by the second focusing element 1226, including, but not limited to, one or more lenses, one or more filters, one or more polarizers, or one or more phase plates.

[0071] System 1200 may be configured as any type of metrology tool known in the art, including, but not limited to, a spectroscopic ellipsometer with one or more illumination angles, a spectroscopic ellipsometer measuring Mueller matrix elements (e.g., using a rotational compensator), a single wavelength ellipsometer, an angle-resolved ellipsometer (e.g., a beam profile ellipsometer), a spectroscopic reflectometer, a single wavelength reflectometer, an angle-resolved reflectometer (e.g., a beam profile reflectometer), an imaging system, a pupil imaging system, a spectroscopic imaging system, a scatterometer, etc.

[0072] Descriptions of inspection / metrology tools suitable for implementation with various embodiments of the present disclosure are found in U.S. patent application Ser. No. 13 / 554,954, filed July 9, 2012, entitled "Wafer Inspection System," U.S. published patent application Ser. No. 2009 / 0180176, published July 16, 2009, entitled "Split Field Inspection System Using Small Catadioptric Objectives," U.S. published patent application Ser. No. 2007 / 0002465, published January 4, 2007, entitled "Beam Delivery System for Laser Dark-Field Illumination in a Catadioptric Optical System," U.S. Patent No. 5,999,310, published December 7, 1999, entitled "Ultra-broadband UV Microscope Imaging System with Wide Range Zoom Capability," U.S. Patent No. 5,999,310, published April 28, 2009, entitled "Surface Inspection System Using Laser Line Illumination with Two Dimensional No. 7,525,649 entitled "Dynamically Adjustable Semiconductor Metrology System" by Wang et al., published May 9, 2013; U.S. Patent Application No. 2013 / 0114085 entitled "Dynamically Adjustable Semiconductor Metrology System" by Wang et al., published May 9, 2013; U.S. Patent No. 5,608,526 entitled "Focused Beam Spectroscopic Ellipsometry Method and System" by Piwonka-Corle et al., published March 4, 1997; and U.S. Patent No. 6,297,880 entitled "Apparatus for Analyzing Multi-Layer Thin Film Stacks on Semiconductors" by Rosencwaig et al., published October 2, 2001, each of which is incorporated herein by reference in its entirety.

[0073] The one or more processors 1120 of the present disclosure may include any one or more processing elements known in the art. In this sense, the one or more processors 1120 may include any microprocessor-type device configured to execute software algorithms and / or instructions. It should be appreciated that the steps described throughout this disclosure may be performed by a single computer system, or alternatively, multiple computer systems. In general, the term "processor" may be broadly defined to encompass any device having one or more processing and / or logic elements, which may execute program instructions from a non-transitory memory medium 1122. Furthermore, different subsystems of the various disclosed systems may include processors and / or logic elements suitable for performing at least a portion of the steps described throughout this disclosure.

[0074] The memory medium 1122 may include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 1120. For example, the memory medium 1122 may include a non-transitory memory medium. For example, the memory medium 1122 may include, but is not limited to, read-only memory, random access memory, magnetic or optical memory devices (e.g., disks), magnetic tape, solid-state drives, etc. In another embodiment, the memory 1122 is configured to store one or more results and / or outputs of the various steps described herein. It is further noted that the memory 1122 may be housed in a common controller housing with one or more processors 1120. In an alternative embodiment, the memory 1122 may be located remotely with respect to the physical location of one or more processors 1120. For example, one or more processors 1120 may access a remote memory (e.g., a server) accessible via a network (e.g., the Internet, an intranet, etc.). In this regard, the one or more processors 1120 of the controller 1118 may perform any of the various process steps described throughout this disclosure.

[0075] In some embodiments, systems 100, 1100, and 1200, as described herein, can be configured as “standalone tools,” which is herein understood to mean tools that are not physically coupled to a process tool. In another embodiment, such inspection or metrology systems can be coupled to a process tool (not shown) by a transmission medium, which may include wired and / or wireless portions. The process tool may include any process tool known in the art, such as a lithography tool, an etching tool, a deposition tool, a polishing tool, a plating tool, a cleaning tool, or an ion implantation tool. Results of the inspection or measurement performed by the systems described herein can be used to modify process or process tool parameters using feedback, feedforward, and / or in-situ control techniques. The process or process tool parameters may be modified manually or automatically.

[0076] Embodiments of systems 100, 1100, and 1200 may be further configured as described herein. In addition, systems 100, 1100, and 1200 may be configured to perform any other step(s) of any of the method embodiment(s) described herein.

[0077] 13 shows a flowchart of a method 1300 for correcting errors induced by a plasma source lamphouse, in accordance with one or more embodiments of the present disclosure. It is noted herein that the steps of method 1300 may be performed in whole or in part by system 100. However, it is further recognized that method 1300 is not limited to system 100 in that additional or alternative system-level embodiments may perform all or a portion of the steps of method 1300.

[0078] In step 1302, pump illumination is generated. For example, pump source 102 may be configured to generate pump illumination 101 and direct pump illumination 101 along pump path 103. Pump source 102 may include any illumination source configured to pump a plasma known in the art, including, but not limited to, one or more lasers, one or more fiber lasers, one or more infrared (IR) lasers, etc.

[0079] In step 1304, the pump illumination 101 is corrected using a first corrector plate. For example, the pump illumination 101 may be corrected by a cylindrical corrector plate 108, as shown in FIG. 1A. As another example, the pump illumination 101 may be corrected by an aspherical corrector plate 128. As previously described herein, correction of the pump illumination 101 by a corrector plate (e.g., corrector plates 108, 128) may be performed to correct one or more aberrations introduced by one or more optical elements of the system 100, including, but not limited to, the plasma lamps 112, 130.

[0080] In step 1306, the pump illumination is collected and focused using a reflector element onto the gas volume contained within the plasma lamp. For example, reflector element 110 may be configured to receive pump illumination 101 and direct it toward the gas volume contained within plasma lamp 112. Reflector element 110 may include an ellipsoidal reflector element. Additionally, reflector element 110 may include an aspherical reflector element. Plasma lamp 112 may take any shape known in the art for containing a gas volume. For example, as shown in FIG. 1A, plasma lamp 112 may include a cylindrical plasma lamp 112. As another example, plasma lamp 112 may include a prolate spheroid-shaped plasma lamp 130, as shown in FIG. 1B. Plasma lamp 112, 130 may include a gas volume containing any gas or mixture of gases known in the art suitable for generating a plasma, including, but not limited to, xenon (Xe), argon (Ar), etc. In one embodiment, the gas volume contained within the plasma lamps 112, 130 may be at high pressure. For example, the gas volume within the plasma lamps 112, 130 may be at 10 atmospheres.

[0081] In step 1308, a plasma is generated within the gas volume contained within the plasma lamp. When the reflector element 110 collects and focuses the pump illumination 101 within the gas volume contained within the plasma lamps 112, 130, a plasma 114 can be generated within the gas volume.

[0082] In step 1310, broadband illumination is generated by the plasma. Broadband illumination 107 may include illumination / radiation of various wavelengths, including but not limited to ultraviolet (UV) radiation, deep ultraviolet (DUV) radiation, vacuum ultraviolet (VUV) radiation, etc.

[0083] In step 1312, one or more aberrations of the broadband illumination are corrected using a second corrector plate. For example, the broadband illumination 107 may be directed to an additional corrector plate 118, 132, where the additional corrector plate 118, 132 is configured to correct one or more aberrations of the broadband illumination 107. In some embodiments, the additional corrector plate 118, 132 includes an aspheric corrector plate.

[0084] Those skilled in the art will recognize that the components (e.g., operations), devices, objects, and accompanying discussion described herein are used as examples for conceptual clarity, and that various configurational variations are contemplated. Thus, as used herein, the specific illustrations set forth and the accompanying discussion are intended to represent their more general classification. In general, the use of a specific illustration is intended to represent that classification and should not be considered a limitation that excludes the specific components (e.g., operations), devices, and objects.

[0085] Those skilled in the art will understand that there are a variety of vehicles (e.g., hardware, software, and / or firmware) capable of implementing the processes and / or systems and / or other techniques described herein, and that the preferred vehicle will vary depending on the context in which the processes and / or systems and / or other techniques are deployed. For example, if the implementer determines that speed and accuracy are paramount, the implementer may select a primarily hardware and / or firmware vehicle; alternatively, if flexibility is paramount, the implementer may select a primarily software implementation, or again alternatively, the implementer may select some combination of hardware, software, and / or firmware. Thus, there are several possible vehicles capable of implementing the processes and / or devices and / or other techniques described herein, and any vehicle utilized is a choice dependent on the context in which it is deployed and the implementer's particular concerns (e.g., speed, flexibility, or predictability), and no vehicle is inherently superior to another, in that any of these may be subject to change.

[0086] The preceding description is presented to enable one skilled in the art to make and use the invention as provided in the context of a particular application and its requirements. As used herein, directional terms such as "top," "bottom," "over," "under," "upper," "upward," "lower," "down," and "downward" are intended to provide relative positions for purposes of description and are not intended to specify an absolute frame of reference. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0087] With respect to the use of substantially any plural and / or singular term herein, those of ordinary skill in the art may translate from the plural to the singular and / or from the singular to the plural as appropriate to the context and / or application. The various singular / plural permutations are not expressly set forth herein for the sake of clarity.

[0088] All methods described herein may include storing results of one or more steps of a method embodiment in memory. The results may include any of the results described herein and may be stored in any manner known in the art. The memory may include any of the memories described herein or any other suitable storage medium known in the art. After storing the results, the results may be accessed in memory, used by any of the method or system embodiments described herein, formatted for display to a user, used by another software module, method, or system, etc. Furthermore, the results may be stored "permanently," "semi-permanently," "temporarily," or for a period of time. For example, the memory may be random access memory (RAM), and the results may not necessarily be retained in memory indefinitely.

[0089] It is further contemplated that each of the method embodiments described above may include any other step(s) of any other method(s) described herein. In addition, each of the method embodiments described above may be performed by any of the systems described herein.

[0090] The subject matter described herein may depict different components contained within or connected to other components. It is understood that architectures so depicted are merely illustrative, and that in fact many other architectures that achieve similar functionality may be implemented. In a conceptual sense, any arrangement of components to achieve similar functionality is effectively “associated” such that the desired functionality is achieved. Thus, any two components herein that combine to achieve a particular functionality may be considered to be “associated” with each other such that the desired functionality may be achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated may be considered to be “connected” or “coupled” with each other to achieve the desired functionality, and any two components so capable of being associated may be considered to be “couplable” with each other to achieve the desired functionality. Specific examples of what is combinable include, but are not limited to, physically interactable and / or physically interacting components, wirelessly interactable and / or wirelessly interacting components, and / or logically interacting and / or logically interoperable components.

[0091] Furthermore, it should be understood that the present invention is defined by the appended claims. In general, it will be understood by those skilled in the art that the terms used herein, particularly in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including but not limited to," etc.). Where a specific number of introduced claim recitations is intended, such intention will be explicitly set forth in the claim, and it will be further understood by those skilled in the art that, in the absence of such a recitation, no such intention exists. For example, to aid in understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to mean that the introduction of a claim recitation with the indefinite article "a" or "an" limits the scope of any particular claim containing the claim recitation so introduced to inventions containing only one such recitation, even if the same claim includes the introductory phrase "one or more" or "at least one" and the indefinite article "a" or "an" (e.g., "a" and / or "an" should generally be interpreted to mean "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. In addition, even when a specific number of introduced claim recitations is explicitly recited, those skilled in the art will recognize that such a recitation should generally be interpreted to mean at least the recited number (e.g., a bare recitation of "two recitations" without other modifiers generally means at least two recitations, or more than two recitations).Furthermore, in instances where phrases similar to "at least one of A, B, and C, etc." are used, such configurations are generally intended to mean what one of ordinary skill in the art would understand the phrase (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In instances where phrases similar to "at least one of A, B, or C, etc." are used, such configurations are generally intended to mean what one of ordinary skill in the art would understand the phrase (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will further be understood by those skilled in the art that virtually any disjunctive word and / or phrase expressing two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0092] The present disclosure and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various modifications can be made in the form, construction and arrangement of the elements without departing from the disclosed subject matter or sacrificing all of its important advantages. The described forms are merely illustrative, and it is intended that the following claims encompass and include all such modifications. It will further be understood that the appended claims define the invention.

Claims

1. The system, 1. A broadband illumination source comprising: a pump source configured to generate pump illumination; a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination; and a broadband illumination source including a reflector element configured to receive the pump illumination and direct the pump illumination toward a gas volume contained within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the gas volume to produce broadband illumination; a detector assembly; a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination toward a sample, the set of characterization optics further configured to direct radiation from the sample to the detector assembly; a second corrector plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, the second corrector plate comprising an aspherical corrector plate; and A system comprising:

2. The surface profile of the second correction plate is [Equation 1] The system of claim 1 , wherein:

3. 1. A method comprising: generating pump illumination; correcting the pump illumination using a correction plate; collecting and focusing the pump illumination using a reflector element into a gas volume contained within the plasma lamp; generating a plasma within the gas volume contained within the plasma lamp; generating broadband illumination using the plasma; directing radiation from the sample to a detector assembly with a set of characterization optics configured to collect at least a portion of the broadband illumination and direct the broadband illumination to the sample; and correcting one or more aberrations of the broadband illumination with a second corrector plate, the second corrector plate comprising an aspheric corrector plate.

4. The method of claim 3 , wherein the plasma lamp comprises a cylindrical plasma lamp.

5. The method of claim 3 , wherein the reflector element comprises an aspherical reflector element.

6. The surface profile of the reflector element is [Equation 2] The method of claim 3 , wherein:

7. The method of claim 3 , wherein the plasma lamp comprises a substantially prolate spheroidal shaped plasma lamp.

8. The method of claim 3 , wherein the corrector plate comprises an aspheric corrector plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

9. The surface profile of the correction plate is [Equation 3] The method of claim 8 , wherein:

10. The method of claim 3 , further comprising directing the broadband illumination through one or more optical elements to a homogenizer.

11. The method of claim 3 , wherein generating pump illumination comprises generating pump illumination using a fiber laser pump source.

Images