Laser-sustained plasma source based on colliding liquid jets

Abstract

The laser sustained broadband light source includes a gas containment structure and a plurality of jet nozzles configured to direct a plurality of liquid jets of plasma forming material to impinge on one another within the gas containment structure, the laser sustained broadband light source further includes a laser pump source configured to generate an optical pump that sustains a plasma within a region of the gas containment structure at points of impingement of the plurality of liquid jets, and a focusing element configured to focus broadband light emitted from the plasma.

Description

Technical Field

[0001] Reference to Related Applications This application claims priority to U.S. Provisional Application No. 63 / 331,895, filed Apr. 18, 2022, which is hereby incorporated by reference in its entirety.

[0002] The present invention generally relates to plasma-based radiation sources, and more particularly to a laser sustained plasma (LSP) broadband light source including a plurality of liquid injections for providing a stable high-density, low-speed gas region within a low-density gas volume for LSP generation.

Background Art

[0003] As the demand for integrated circuits with increasingly smaller device features continues to grow, there is an ongoing need for improved illumination sources for inspecting these increasingly shrinking devices. One such illumination source includes a laser sustained plasma (LSP) radiation source. Laser sustained plasma light sources can generate high-power broadband light. Laser sustained plasma light sources operate by focusing laser radiation into a gas volume to excite a gas, such as argon or xenon, into a plasma state capable of emitting light. This effect is typically referred to as “pumping” the plasma.

[0004] Increasing the radiance of an LSP source requires maintaining the plasma in a high-pressure environment to achieve a higher gas density in the plasma region. Typical high-density gas-based LSP sources rely on high-pressure gas to reach the required plasma density. For example, in broadband plasma (BBP) sources, the operating pressure is around 100 bar. High gas density can be achieved by high-pressure convection gas chamber volume or by injecting high-pressure gas into a low-pressure chamber volume. Fluctuations in the flow of convection gas volume can lead to plasma instability. The above solutions also require additional safety controls because large amounts of compressed gas are needed. In addition, these plasmas can exhibit limited radiance due to the surrounding gas volume heated by the pump light, thereby increasing the plasma size and lowering the plasma temperature because absorbed light does not reach the plasma center.

[0005] The use of liquid injection has been proposed to provide a localized high-density gas to be delivered to the LSP. In this case, the LSP should burn near the surface of the liquid. The evaporated liquid rapidly expands to a low-pressure volume, providing a high-density gradient. The high local density and corresponding pressure cause a high-speed gas flow through the plasma region, which can prevent the plasma from being sustained. To maintain the plasma in the supersonic gas flow expected for such a configuration, very high pump power (over approximately 100 kW CW) is required. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0136901 [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, it would be desirable to provide a system and method that solves one or more of the shortcomings of the previous approaches identified above. [Means for solving the problem]

[0008] A laser-maintained broadband light source is disclosed according to one or more embodiments of the present disclosure. In embodiments, the light source includes a gas containment structure. In embodiments, the light source includes a plurality of injection nozzles, which are configured to direct a plurality of liquid injections to collide within the gas containment structure, and the plurality of liquid injections include a first liquid injection and at least a second injection. In embodiments, the light source includes a laser pump source configured to generate an optical pump to maintain plasma within a region of the gas containment structure at the collision points of the plurality of liquid injections. In embodiments, the light source includes a focusing element configured to focus at least a portion of the broadband light emitted from the plasma. In embodiments, the broadband light source can be incorporated into an optical characterization system, such as an optical inspection system or a measurement system.

[0009] A method for generating broadband light is disclosed according to one or more embodiments of the present disclosure. In an embodiment, the method includes the step of generating a plurality of liquid jets that collide within a gas containment structure, wherein the plurality of liquid jets include a first liquid jet and at least a second jet. In an embodiment, the method includes the step of generating an optical pump. In an embodiment, the method includes the step of focusing the optical pump to a region of the gas containment structure at the collision points of the plurality of liquid jets in order to maintain plasma in a region of the gas containment structure at the collision points of the plurality of liquid jets. In an embodiment, the method includes the steps of focusing a portion of broadband light emitted from the plasma and delivering a portion of the broadband light to one or more optical elements outside the gas containment structure.

[0010] It should be understood that both the above summary and the following detailed description are illustrative and descriptive, and do not necessarily limit the scope of this disclosure. The accompanying drawings incorporated herein and forming part of this disclosure illustrate the subject matter of this disclosure. Both the description and the drawings serve to illustrate the principles of this disclosure.

[0011] Many of the advantages of this disclosure can be better understood by those skilled in the art by referring to the accompanying drawings. [Brief explanation of the drawing]

[0012] [Figure 1A] A simplified schematic diagram of a broadband LSP light source having two liquid jets for supplying plasma generation material, according to one or more embodiments of the present disclosure, is shown. [Figure 1B] A conceptual diagram of a broadband LSP light source having two liquid jets for supplying plasma generation material, according to one or more embodiments of the present disclosure, is shown. [Figure 2] A simplified schematic diagram of an LSP broadband light source having an annular pump optical element according to one or more embodiments of the present disclosure is shown. [Figure 3] A simplified schematic diagram of an optical characterization system for implementing an LSP radiation source, according to one or more embodiments of the present disclosure, is shown. [Figure 4] This flowchart illustrates a method for generating broadband light according to one or more embodiments of the present disclosure. [Modes for carrying out the invention]

[0013] Herein, we refer in detail to the disclosed subject matter shown in the accompanying drawings. This disclosure has been specifically shown and described with respect to particular embodiments and their particular features. The embodiments described herein are to be construed as illustrative rather than restrictive. It should be readily apparent to those skilled in the art that various changes and modifications in form and detail can be made without departing from the spirit and scope of this disclosure.

[0014] Generally referring to Figures 1 to 4, one or more embodiments of the present disclosure describe a laser-sustained plasma (LSP) broadband source having multiple impacting liquid jets. Embodiments of the present disclosure relate to an LSP broadband source including two or more impacting high-density, high-velocity liquid jets in a low-gas-density environment. The impacting jets create a stable region of high-density, low-velocity gas at their impact points. The velocity at the impact points approaches zero. At these impact points, the LSP can be generated by focusing a pump laser to this point. Having a region of near-zero velocity helps ensure plasma persistence at lower pump power. Outside the high-pressure, low-velocity region, the gas expands freely. The outer region is a gas outflow region characterized by lower gas density and increasing velocity. The gas pressure decreases rapidly as a function of distance from the impact points. For example, the pressure can decrease from over 100 bar at the impact points of the jets to less than 20 bar within a few hundred microns (e.g., 200-500 microns) of the impact points. Even if plasma is maintained in this peripheral region, it is optically thin due to its low gas density, enabling efficient laser coupling to the plasma's center and allowing for the focusing of light without reabsorption in these peripheral regions.

[0015] Figure 1A shows a simplified schematic diagram of a broadband LSP light source 100 according to one or more embodiments of the present disclosure. In the embodiments, the LSP broadband light source 100 includes a set of injection nozzles for generating a set of liquid injections that collide with a gas containment chamber 106. For example, the set of injection nozzles may include a first injection nozzle 102a and a second injection nozzle 102b for delivering target material injections 104a and 104b, respectively, to collide within the gas containment structure 106 (e.g., a chamber, a lamp, or a cell). The LSP source 100 may also include a laser pump source 108, a pump laser focusing optical system 110, and a focusing element 120. Note that Figure 1A shows the case where the gas containment structure 106 is a gas containment chamber. For the purposes of the present disclosure, the gas containment structure is referred to as a gas containment chamber 106, but the scope of the present disclosure should not be limited to a chamber, as any gas containment vessel is within the scope of the present disclosure. For example, the gas containment structure 106 may include, but is not limited to, a plasma chamber, a plasma cell, or a plasma lamp.

[0016] The LSP source 108 may be configured to generate a pump beam 112 that acts as an optical pump to maintain plasma 116 within the region of the chamber 106 at the collision point of the liquid jets 104a and 104b. The pump beam 112 can be focused by a pump-laser focusing optical system 110. In an embodiment, the pump-laser focusing optical system 110 directs the pump beam 112 into the chamber 106 through a pump-laser window 114 and focuses the pump beam 112 at the collision point between the first liquid jet stream 104a and the second liquid jet stream 104b to generate and / or maintain plasma 116. It should be noted that the pump-laser focusing optical system 110 may include, but is not limited to, any optical elements known in the art for directing and / or focusing radiation, including lenses, mirrors, prisms, polarizers, gratings, filters, or beam splitters.

[0017] The pump source 108 can include any pump source known in the art suitable for igniting and / or maintaining the plasma. For example, the pump source 108 may include one or more lasers (e.g., pump lasers). In an embodiment, the pump source 108 includes one or more continuous wave (CW) laser sources. For example, the pump source 108 may include one or more CW infrared laser sources. In an embodiment, the pump source 108 can include one or more pulsed lasers configured to supply pulsed laser light to the plasma 116. For example, the pump source 108 may include one or more pulsed lasers having a repetition rate greater than 50 kHz (e.g., greater than 100 kHz). In an embodiment, the pump source 108 may include a combination of one or more CW and one or more pulsed lasers.

[0018] The pump beam 112 can include radiation of any wavelength or wavelength range known in the art, including, but not limited to, infrared (IR) radiation, near-infrared (NIR) radiation, ultraviolet (UV) radiation, visible radiation, or other radiation suitable for forming a plasma when incident on a suitable target material.

[0019] It should be noted that herein, the LSP broadband light source 100 can include one or more additional ignition sources used to facilitate the generation of the plasma 116 without departing from the spirit or scope of the present disclosure. For example, the chamber 106 can include one or more electrodes capable of initiating and / or maintaining the plasma 116.

[0020] In embodiments, broadband light 118 generated by the plasma 116 exits the chamber 106 through one or more apertures 122. For example, a focusing element 120 can be positioned to collect broadband light 118 from the plasma 116 and then pass at least a portion of the collected broadband light through one or more apertures 122. In embodiments, one or more apertures 122 include one or more windows (e.g., a material transparent to broadband light). In embodiments, one or more apertures 122 are windowless and located in the wall of the chamber 106. One or more apertures 122 may include, but are not limited to, holes, ports, outlets, vents, spaces, or any other openings that allow broadband light 118 to exit the chamber 106 through the wall of the chamber 106, and may be windowed or windowless.

[0021] In this embodiment, the chamber 106 is fluidically connected to a vacuum pump 126. In this embodiment, the pressure in the chamber 106 is maintained at a selected pressure. The vacuum pump 126 can remove gas (e.g., gas emitted from the plasma, buffer gas) from the chamber 106 to maintain the selected pressure in the chamber 106. It should be noted that gas removal can be performed at the same rate as the total inflow rate from the injection. In addition, the pressure in the chamber 106 should be maintained at a level low enough to reduce laser light absorption around the plasma 116.

[0022] In an embodiment, the condenser 120 includes one or more optical elements known in the art that are configured to collect broadband light 118, including but not limited to one or more mirrors, one or more prisms, one or more lenses, one or more diffractive optical elements, one or more parabolic mirrors, one or more elliptical mirrors, and the like. It should be noted that in this specification, the condenser 120 can be configured to collect and / or focus the broadband light 118 generated by the plasma 116, which is used in one or more downstream processes including but not limited to an imaging process, an inspection process, a measurement process, a lithography process, etc. For example, the condenser 120 can direct the broadband light 118 to the collection position 128. For example, the condenser 120 can deliver infrared radiation, visible radiation, NUV radiation, UV radiation, DUV radiation, and / or VUV radiation to an optical element downstream of any optical property evaluation system known in the art, such as but not limited to an inspection tool, a measurement tool, or a lithography tool. In this regard, the broadband light 118 can be coupled to the illumination optical system of an inspection tool, a measurement tool, or a lithography tool.

[0023] FIG. 1B shows a conceptual diagram of a broadband LSP light source 100 according to one or more embodiments of the present disclosure. The collision jets 104a, 104b generate a stable high-density and low-velocity region 130 at their collision point. By canceling out the individual momenta of the jets, the velocity of the gas within the region 130 approaches zero. Having a velocity close to zero helps ensure the sustainability of the plasma 116 at lower pump power. Outside the high-density and low-velocity region 130, the gas freely expands into the gas outflow region 132, which is characterized by a lower gas density and a higher velocity.

[0024] In this embodiment, the gas pressure in the plasma 116 is 50 to 500 bar. To reach such a pressure, the liquid injections 104a and 104b must have sufficient diameter and velocity. Such high pressure can be achieved with a liquid injection velocity of approximately 50 to 200 m / s (e.g., 75 to 125 m / s). In this embodiment, the diameter of the injections 104a and 104b is 50 to 500 microns (e.g., 150 to 250 microns). The injections 104a and 104b can be completely evaporated by the heat and radiation emitted from the plasma 116.

[0025] In this embodiment, the gas pressure decreases rapidly as a function of the distance from the collision point of the injections 104a and 104b. In this regard, the pressure can decrease from over 100 bar to less than 20 bar within several hundred microns (e.g., 200-500 microns) from the collision point. Furthermore, even if the plasma is maintained in this peripheral region, it is optically thin due to the low gas density, which allows for efficient laser coupling to the central region of the plasma 116 and also allows for focusing the light without reabsorption of broadband light 118 in the peripheral region of the plasma 116.

[0026] The injections 104a and 104b may contain any material suitable for generating plasma. In embodiments, the injection may include a liquid injection of a cryogenically cooled liquid. For example, the liquid may include, but is not limited to, liquid Ar, liquid Kr, liquid Xe, liquid N2, liquid CH4, liquid NH3, etc. In embodiments, the jet may include a jet of a liquid that is maintained at room temperature. For example, the liquid may include, but is not limited to, liquid H2O, etc. In embodiments, one or more materials may be delivered as a solvent in a solute. For example, one or more salts (e.g., salts of heavy metals) can be dissolved in a liquid (e.g., H2O) and delivered to the chamber 106 via injections 104a and 104b. In embodiments, one or more materials may be delivered as a suspension in a liquid. For example, the suspension may include, but is not limited to, a metal suspended in water, Xe suspended in liquid N2, etc. In embodiments, two or more materials may be delivered as a mixture. For example, examples of liquid mixtures include, but are not limited to, mixtures of Ar and Xe, or mixtures of Ar, Kr, and Xe.

[0027] In the embodiment, the injections 104a and 104b can deliver a mixture of liquid and gaseous materials. For example, the injections 104a and 104b may include, but are not limited to, gas-liquid mixtures such as Ar / Xe and Ar / Kr.

[0028] In embodiments, the injections 104a and 104b may include solid materials. For example, the injections 104a and 104b may include solid H2O or solid Xe. It should be noted herein that solid injection may be employed in a lower pressure chamber than that experienced by liquid injection on its way to the point of impact.

[0029] While much of the description focuses on describing an LSP source 100 having two injection nozzles 102a, 102b and two injections 104a, 104b, it should be noted that in this specification, such descriptions are provided solely for convenience and clarity. It should be noted that the LSP source 100 is not limited to two injection nozzles and two injections, and the LSP source 100 may include any number of injection nozzles and corresponding injections. For example, the LSP source 100 may include two, three, four, five, six, seven, eight (etc.) injection nozzles and corresponding injections.

[0030] Figure 2 shows a simplified schematic diagram of a broadband LSP light source 100 according to one or more embodiments of the present disclosure. In this embodiment, the pump laser focusing optical system 110 may include one or more annular optical systems. For example, the pump laser focusing optical system 110 may include an annular mirror. For example, as shown in Figure 2, the pump laser focusing optical system 110 may include an annular mirror positioned such that the center point of the mirror is located at the same location as the collision point between the first jet 104a and the second jet 104b. Such an arrangement directs the pump illumination 112 from the pump source 108 (not shown in Figure 2 for clarity) to the collision point between the first jet 104a and the second jet 104b.

[0031] The generation of laser-sustained plasma is also generally described in U.S. Patent No. 7,435,982 (October 14, 2008), which is incorporated herein by reference in whole. The generation of plasma is also generally described in U.S. Patent No. 7,786,455 (August 31, 2010), which is incorporated herein by reference in whole. The generation of plasma is also generally described in U.S. Patent No. 7,989,786 (August 2, 2011), which is incorporated herein by reference in whole. The generation of plasma is also generally described in U.S. Patent No. 8,182,127 (May 22, 2012), which is incorporated herein by reference in whole. The generation of plasma is also generally described in U.S. Patent No. 8,309,943 (November 13, 2012), which is incorporated herein by reference in whole. Plasma generation is also generally described in U.S. Patent No. 8,525,138 (February 9, 2013), which is incorporated herein by reference in its entirety. Plasma generation is also generally described in U.S. Patent No. 8,921,814 (December 30, 2014), which is incorporated herein by reference in its entirety. Plasma generation is also generally described in U.S. Patent No. 9,318,311 (April 19, 2016), which is incorporated herein by reference in its entirety. Plasma generation is also generally described in U.S. Patent No. 9,390,902 (July 12, 2016), which is incorporated herein by reference in its entirety. In a general sense, the various embodiments of this disclosure should be interpreted as extending to any plasma-based light source known in the art.

[0032] Figure 3 shows a simplified schematic diagram of an optical characterization system 300 implementing an LSP broadband light source 100 according to one or more embodiments of the present disclosure. In the embodiments, the system 300 includes the LSP light source 100, an illumination arm 303, a focusing arm 305, a detector assembly 314, and a controller 318 including one or more processors 320 and memory 322.

[0033] It should be noted that, as described herein, system 300 may include any imaging, inspection, measurement, lithography, or other characterization systems known in the art. In this regard, system 300 may be configured to perform inspection, optical measurement, lithography, and / or any form of imaging on sample 307. Sample 307 may include any sample known in the art, including but not limited to wafers, reticles, photomasks, etc. It should be noted that system 300 may incorporate one or more of the various embodiments of the LSP light source 100 described throughout this disclosure.

[0034] In the embodiment, the sample 307 is placed on a stage assembly 312 to facilitate the movement of the sample 307. The stage assembly 312 may include any stage assembly known in the art, including, but not limited to, an XY stage, an R-0 stage, etc. In the embodiment, the stage assembly 312 can adjust the height of the sample 307 during inspection or imaging to maintain focus on the sample 307.

[0035] In this embodiment, the illumination arm 303 is configured to direct broadband light 118 from the LSP broadband light source 100 onto the sample 307. The illumination arm 303 may include any number and type of optical components known in the art. In this embodiment, the illumination arm 303 includes one or more optical components 302, a beam splitter 304, and an objective lens 306. In this regard, the illumination arm 303 may be configured to focus broadband light 118 from the LSP broadband light source 100 onto the surface of the sample 307. The one or more optical components 302 may include, but are 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. It should be noted that the focusing position 128 may include, but is not limited to, one or more of the optical components 302, the beam splitter 304, or the objective lens 306.

[0036] In the embodiment, the system 300 includes a focusing arm 305 configured to collect light reflected, scattered, diffracted, and / or emitted from the sample 307. In the embodiment, the focusing arm 305 can direct and / or focus the light from the sample 307 to the sensor 316 of the detector assembly 314. It should be noted that the sensor 316 and the detector assembly 314 may include any sensor and detector assembly known in the art. The sensor 316 may include, but is not limited to, a CCD sensor or a CCD-TDI sensor. Furthermore, the sensor 316 may include, but is not limited to, a line sensor or an electron shock line sensor.

[0037] In an embodiment, the detector assembly 314 is communicatively coupled to a controller 318 which includes one or more processors 320 and memory 322. For example, one or more processors 320 may be communicatively coupled to memory 322 and configured to execute a set of program instructions stored in memory 322. In an embodiment, one or more processors 320 are configured to analyze the output of the detector assembly 314. In an embodiment, the set of program instructions is configured to cause one or more processors 320 to analyze one or more characteristics of sample 307. In an embodiment, the set of program instructions is configured to cause one or more processors 320 to modify one or more characteristics of system 300 in order to maintain focus on sample 307 and / or sensor 316. For example, one or more processors 320 may be configured to adjust the objective lens 306 or one or more optical elements 302 to focus broadband light 118 from the LSP broadband light source 100 onto the surface of sample 307. As another example, one or more processors 320 may be configured to collect illumination from the surface of the sample 307 and adjust the objective lens 306 and / or one or more optical elements 310 to focus the collected illumination onto the sensor 316.

[0038] It should be noted that System 300 may be composed of any optical configuration known in the art, including but not limited to dark-field configurations and bright-field orientations. System 300 may be composed of any type of measuring tool known in the art, such as, but not limited to, a spectroscopic ellipsometer having one or more illumination angles, a spectroscopic ellipsometer for measuring Müller matrix elements (e.g., using a rotational compensator), a single-wavelength ellipsometer, an angle-resolved ellipsometer (e.g., a beam-profile ellipsometer), a spectrophotometer, a single-wavelength reflectometer, an angle-resolved reflectometer (e.g., a beam-profile reflectometer), an imaging system, a pupil imaging system, a spectral imaging system, or a scatometer.

[0039] Further details of various embodiments of the optical property evaluation system 300 are incorporated herein by reference in their entirety by U.S. Patent No. 7,957,066; U.S. Patent Application Publication 2007 / 0002465; U.S. Patent No. 5,999,310; U.S. Patent No. 7,525,649; U.S. Patent Application Publication 2013 / 0114085; U.S. Patent No. 5,608,526; and U.S. Patent No. 6,297,880.

[0040] One or more processors 320 in this disclosure may include any one or more processing elements known in the art. In this sense, one or more processors 320 may include any microprocessor type device configured to execute software algorithms and / or instructions. In embodiments, one or more processors 320 may consist of a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, or other computer systems (e.g., networked computers) configured to execute a program configured to operate system 300 and / or LSP broadband light source 100, as described throughout this disclosure. It should be recognized that the steps described throughout this disclosure may be performed by a single computer system or, alternatively, by multiple computer systems. Generally, the term “processor” may be broadly defined to include any device having one or more processing elements that execute program instructions from a non-temporary memory medium 322. Furthermore, different subsystems of the various systems disclosed may include processors or logic elements suitable for performing at least some of the steps described throughout this disclosure. Thus, the above description should not be construed as an limitation to this disclosure, but merely as an example.

[0041] The memory medium 322 may include any storage medium known in the art that is suitable for storing program instructions that can be executed by one or more associated processors 320. For example, the storage medium 322 may include non-temporary storage media. For example, the memory medium 322 may include, but is not limited to, read-only memory, random-access memory, magnetic or optical memory devices (e.g., disks), magnetic tapes, solid-state drives, etc. In embodiments, the memory 322 is configured to store one or more results and / or outputs of various steps described herein. Furthermore, it should be noted that the memory 322 may be housed in a common controller housing together with one or more processors 320. In alternative embodiments, the memory 322 may be located remotely from the physical location of the processors 320. For example, one or more processors 320 may have access to remote memory (e.g., a server) accessible via a network (e.g., the Internet, an intranet, etc.). In embodiments, the memory medium 322 holds program instructions for one or more processors 320 to perform various steps described throughout this disclosure.

[0042] Figure 4 shows a flowchart illustrating a method 400 for generating broadband light 118 according to one or more embodiments of the present disclosure. It should be noted herein that the steps of method 400 may be implemented in whole or in part by an LSP broadband light source 100. However, it should be further recognized that method 400 is not limited to the LSP light source 100, in that additional or alternative system-level embodiments may perform all or part of the steps of method 400.

[0043] In step 402, a set of liquid jets is generated and positioned to collide within the gas containment structure. In this embodiment, multiple liquid jet nozzles 102a, 102b deliver liquid jets 104a, 104b into the chamber 106 so as to collide at the plasma generation location. The jet nozzles 102a, 102b can be fluidically coupled to one or more material sources (e.g., volumes of liquid stored in one or more containers). For example, each jet nozzle 102a, 102b may be fluidically coupled to a single liquid container (not shown). In another example, each jet nozzle 102a, 102b may be fluidically coupled to separate, independent liquid containers. In this example, the jet nozzles 102a, 102b can provide jets of the same or different materials.

[0044] In step 404, an optical pump is generated. In this embodiment, the pump source 108 generates a laser illumination 112 that acts as an optical pump for the plasma 116.

[0045] In step 406, the optical pump is focused into the region of the gas containment structure at the collision points of the multiple liquid jets 104a, 104b, and the plasma 116 is maintained in the region of the gas containment structure at the collision points of the liquid jets. For example, one or more pump focusing optics 110 may be used to focus the pump illumination 112 into the region of the chamber 106 through a window 114 at the collision points of the multiple liquid jets 104a, 104b, and to maintain the plasma 116 at the collision points of the liquid jets 104a, 104b.

[0046] In step 408, a portion of the broadband light 118 from the plasma 116 is focused. For example, a portion of the broadband light 118 may be focused and delivered through an opening 122 in the wall of the chamber 106 to one or more optical elements outside the chamber 106 at a collection position 128.

[0047] Those skilled in the art will recognize that the components, actions, devices, objects, and accompanying discussions described herein are used as examples for conceptual clarity, and that various configuration modifications are considered. Therefore, as used herein, the specific examples and accompanying discussions described are intended to be representative of their more general class. In general, the use of any particular example is intended to represent its class, and the exclusion of specific components (e.g., actions), devices, and objects should not be interpreted as limitation.

[0048] With regard to the use of substantially any plural and / or singular terms herein, those skilled in the art can convert from plural to singular and / or singular to plural as appropriate to the context and / or use. Various singular / plural substitutions are not explicitly stated herein for the sake of clarity.

[0049] The subject matter described herein illustrates different components that, in some cases, are contained within or connected to other components. It should be understood that such depicted architectures are merely illustrative, and in practice, many other architectures can be implemented to achieve the same functionality. Conceptually, any arrangement of components to achieve the same function is effectively “associated” in such a way that the desired function is achieved. Thus, any two components in this specification combined to achieve a particular function, whether in architecture or as intermediate components, can be considered “associated” with each other in such a way that the desired function is achieved. Similarly, any two such associated components can also be considered “connected” or “joined” with each other in such a way that the desired functionality is achieved, and any two components that can be associated in such a way can also be considered “joinable” with each other in such a way that the desired functionality is achieved. Specific examples of joinable components include, but are not limited to, physically joinable and / or physically interacting components and / or wirelessly interactable and / or wirelessly interacting components and / or logically interacting and / or logically interactable components.

[0050] Furthermore, it should be understood that the present invention is defined by the appended claims. Generally, it will be understood by those skilled in the art that the terms used herein and in particular in the appended claims (e.g., the body of the appended claims) are generally intended to be “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “at least having,” and the term “includes” should be interpreted as “includes but not limited to,” etc.). It will further be understood by those skilled in the art that if a specific number of claims to be introduced is intended, such intention will be explicitly stated in that claim, and if such statement is not made, such intention does not exist. For example, for the sake of understanding, the following appended claims may include introducing the claims using the introductory phrases “at least one” and “one or more.” However, the use of such phrases should not be interpreted as meaning that the introduction of a claim description with the indefinite article "a" or "an" limits any particular claim containing such introduced description to an invention containing only one such description. The same applies to the use of clear articles used to introduce a claim description, even if the same claim contains an introductory phrase such as "one or more" or "at least one" and an indefinite article such as "a" or "an" (for example, "a" and / or "an" should typically be interpreted as meaning "at least one" or "one or more"). Furthermore, even if a specific number of claims being introduced is explicitly listed, it will be recognized that such descriptions should typically be interpreted as meaning at least the number listed (for example, a bare list of "two lists" without other modifying factors typically means at least two lists, or two or more lists).Furthermore, in instances where conventional expressions similar to "at least one of A, B, and C" are used, such configurations are generally intended to be understood by those skilled in the art as conventional expressions (for example, "a system having at least one of A, B, and C" includes, but is not limited to, a system having only A, a system having only B, a system having only C, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having both A, B, and C). Where conventional expressions similar to "at least one of A, B, or C" are used, such constructions are generally intended to be understood by those skilled in the art as conventional expressions (for example, "a system having at least one of A, B, or C" includes, but is not limited to, a system having only A, a system having only B, a system having only C, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having both A, B, and C). It will further be understood by those skilled in the art that virtually any disjunct words and / or phrases presenting two or more alternative terms, wherever they appear in the description, claims, or drawings, should be understood as intending to include 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 possibility of "A" or "B" or "A and B".

[0051] Many of the present disclosure and its associated advantages will be understood from the foregoing description, and it will become clear that various modifications can be made to the form, structure, and arrangement of the components without departing from the disclosed subject matter or sacrificing any of its material advantages. The described forms are for illustrative purposes only, and it is the intent of the following claims to encompass and include such modifications. Furthermore, it should be understood that the present invention is defined by the appended claims.

Claims

1. A broadband light source, Gas containment structure, A plurality of injection nozzles, configured to direct a plurality of liquid injections to collide within the gas containment structure, wherein the plurality of liquid injections include a first liquid injection and at least a second injection. A laser pump source configured to generate an optical pump to maintain plasma in the region of the gas containment structure at the collision points of the plurality of liquid injections, A light-gathering element configured to focus at least a portion of the broadband light emitted from the plasma, A broadband light source including

2. The broadband light source according to claim 1, characterized in that the plurality of injection nozzles include two or more injection nozzles.

3. The broadband light source according to claim 2, characterized in that the plurality of injection nozzles include three or more injection nozzles.

4. The broadband light source according to claim 1, further comprising one or more pump focusing optical systems for focusing the optical pump within the gas containment structure to the collision point of the plurality of liquid injections.

5. The broadband light source according to claim 4, characterized in that the one or more pump focusing optical systems include at least one of a lens or a mirror.

6. The broadband light source according to claim 5, characterized in that the one or more pump focusing optical systems comprise one or more annular optical elements.

7. The broadband light source according to claim 1, characterized in that the plurality of injection nozzles are fluidly connected to one or more liquid sources.

8. The broadband light source according to claim 1, characterized in that the high-pressure region surrounding the collision point is maintained at a pressure of at least 20 bar.

9. The broadband light source according to claim 8, characterized in that the low-pressure region outside the high-pressure region is maintained at a pressure of less than 20 bar.

10. The broadband light source according to claim 1, characterized in that the diameter of each of the plurality of liquid jets is 50 to 300 microns.

11. The broadband light source according to claim 1, characterized in that the velocity of each of the plurality of liquid injections is 10 to 500 m / s.

12. The aforementioned plurality of liquid injections include at least one Ar, Kr, Xe, N ２ , H ２ O, CH ４ , and NH ３ A broadband light source according to claim 1, characterized by including at least one of the liquid jets.

13. The broadband light source according to claim 1, characterized in that the plurality of liquid jets include at least one of liquid jets of a mixture of materials.

14. The broadband light source according to claim 1, characterized in that the plurality of liquid jets include at least one suspension of a material in a liquid.

15. The broadband light source according to claim 1, characterized in that the plurality of liquid jets include at least one solute in the solvent.

16. The broadband light source according to claim 1, characterized in that the laser pump source comprises at least one of one or more CW lasers or one or more pulsed lasers.

17. The broadband light source according to claim 1, characterized in that the gas containment structure comprises at least one of a plasma chamber, a plasma cell, or a plasma lamp.

18. It is a system, A broadband light source, Gas containment structure, A plurality of injection nozzles, configured to direct a plurality of liquid injections to collide within the gas containment structure, wherein the plurality of liquid injections include a first liquid injection and at least a second injection. A laser pump source configured to generate an optical pump to maintain plasma in the region of the gas containment structure at the collision points of the plurality of liquid injections, A light-gathering element configured to focus at least a portion of the broadband light emitted from the plasma, A broadband light source including, A set of illumination optics configured to guide broadband light from the aforementioned light-collecting element to one or more samples, Detector assembly and A set of projection optical systems configured to receive illumination from the surface of one or more samples and direct the illumination from the one or more samples toward the detector assembly, A system that includes this.

19. It is a method, A step of generating multiple liquid injections and causing them to collide within a gas containment structure, wherein the multiple liquid injections include a first liquid injection and at least a second injection. Steps to generate an optical pump, The steps include focusing the optical pump onto the region of the gas containment structure at the collision points of the plurality of liquid jets, and maintaining the plasma in the region of the gas containment structure at the collision points of the plurality of liquid jets, The steps include: collecting a portion of the broadband light emitted from the plasma and sending a portion of the broadband light to one or more optical elements outside the gas containment structure; A method that includes this.

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