X-ray generation device with cooled diamond substrate

Abstract

The present disclosure provides a device for generating x-rays, comprising: an anode configured to convert an electron beam to an x-ray beam; a diamond substrate in thermal contact with the anode and configured to absorb heat generated in the anode; and a cooling system configured to cool the diamond substrate to a temperature below -60 degrees Celsius. The device enables efficient x-ray generation while managing heat dissipation through the use of a cooled diamond substrate with high thermal conductivity.

Description

X-RAY GENERATION DEVICE WITH COOLED DIAMOND SUBSTRATE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US provisional patent No. 63 / 652,670, filing date May 28, 2024 which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] X-ray analysis tools play a crucial role in semiconductor process control metrology, enabling precise measurements of film composition, thickness, dopant levels, and other critical parameters. These tools rely on the generation of x-rays to excite and analyze materials on semiconductor wafers. The throughput of such tools is largely determined by the time required to acquire a sufficient signal-to-noise ratio from the analysis site.

[0003] One factor affecting the acquisition time is the available x-ray flux. A higher x-ray flux can potentially reduce analysis time and increase overall throughput. However, generating higher x-ray fluxes presents challenges in terms of heat management and maintaining consistent output over time.

[0004] Conventional x-ray sources often utilize anodes to convert electron beam energy into x-rays. These anodes are typically made of materials such as aluminum, tungsten, or other metals chosen for their x-ray emission characteristics. The interaction between the electron beam and the anode material produces both characteristic x-rays and a continuous spectrum of bremsstrahlung radiation.

[0005] The efficiency of x-ray generation in these systems is relatively low, with only a small percentage of the incident electron beam energy being converted to usable x- rays. The majority of the energy is transformed into heat within the anode. This heat generation can lead to various issues, including anode degradation, inconsistent x-ray output, and potential damage to the x-ray source components.

[0006] Existing approaches to managing heat in x-ray sources include water cooling systems and periodic movement of the electron beam to fresh spots on the anode surface. While these methods have enabled the operation of x-ray analysis tools, there remains room for improvement in terms of heat dissipation efficiency, x-ray flux stability, and overall system performance.

[0007] Advanced semiconductor manufacturing processes require increasingly precise metrology capabilities. This drives a need for x-ray analysis tools with higher throughput, improved stability, and enhanced measurement accuracy. Achieving these goals may involve innovations in x-ray source design, including novel approaches to heat management and optimization of x-ray generation efficiency.

[0008] As semiconductor device features continue to shrink and new materials are introduced into fabrication processes, the demands on x-ray analysis tools are likely to grow. Addressing these challenges may require advancements in various aspects of x-ray source technology, from anode materials and designs to cooling systems and electron beam control.SUMMARY

[0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0010] According to an aspect of the present disclosure, a device for generating x- rays is provided. The device includes an anode configured to convert an electron beam to an x-ray beam. The device also includes a diamond substrate in thermal contact with the anode and configured to absorb heat generated in the anode. The device further includes a cooling system configured to cool the diamond substrate to a temperature below -60 degrees Celsius.

[0011] According to other aspects of the present disclosure, the device may include one or more of the following features. The anode may include a material selected from the group consisting of aluminum, chromium, silver, carbon, graphitized carbon, HOPG carbon, neodymium, gadolinium, terbium, tungsten, platinum, lead, and diamond. The anode may have a thickness between 0.5 microns and 5 microns. The device may further include an electron beam source configured to generate the electron beam with an energy between 1 keV and 20 keV. The electron beam source may be configured to generate the electron beam with a flat-top profile. The cooling system may be configured to cool the diamond substrate to a temperature between -80 degrees Celsius and -90 degrees Celsius. The diamond substrate may include boron-doped diamond having a thermal conductivityof approximately 3750 W / mK at the temperature between -80 degrees Celsius and -90 degrees Celsius.

[0012] According to another aspect of the present disclosure, a method for generating x-ray beams is provided. The method includes converting, by an anode, an electron beam that illuminates the anode to an x-ray beam. The method also includes absorbing, by a diamond substrate in thermal contact with the anode, heat generated in the anode as a result of the illumination of the anode with the electron beam. The method further includes cooling the diamond substrate to a temperature below -60 degrees Celsius.

[0013] According to another aspect of the present disclosure, a method for designing a device for generating x-rays is provided. The method includes obtaining information regarding one or more relationships between one or more anode related parameters. The method also includes designing the device using at least one anode related parameter based on the one or more relationships, wherein the device includes an anode configured to convert an electron beam to an x-ray beam, and a diamond substrate in thermal contact with the anode and configured to be cooled to a temperature below -60 degrees Celsius.

[0014] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.BRIEF DESCRIPTION OF FIGURES

[0015] Non-limiting and non- exhaustive examples are described with reference to the following figures.

[0016] FIG. 1 illustrates a bremsstrahlung spectrum for x-ray generation, according to aspects of the present disclosure.

[0017] FIG. 2 depicts an interaction diagram of an electron beam with an anode, according to an embodiment.

[0018] FIG. 3 shows a graph of x-ray flux versus anode thickness at different electron beam energies, according to aspects of the present disclosure.

[0019] FIG. 4 illustrates a graph of x-ray flux versus electron beam current at various energies, according to an embodiment.

[0020] FIG. 5 depicts a graph showing electron beam intensity distribution across the beam profile, according to aspects of the present disclosure.

[0021] FIG. 6 illustrates a block diagram of an x-ray generation device, according to an embodiment.

[0022] FIG. 7 shows a flowchart of a method for generating x-rays, according to aspects of the present disclosure.

[0023] FIG. 8 depicts a flowchart of a method for designing an x-ray generation device, according to an embodiment.DETAILED DESCRIPTION

[0024] The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0025] X-ray generation devices may be used in semiconductor process control metrology applications, including soft x-ray metrology (XRS), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence (XRF) metrologies. These devices may produce x-rays with energy ranges suitable for various metrology techniques, such as 0.062-0.62 keV for soft x-ray metrology and 1-10 keV for Auger, XPS, and XRF metrologies.

[0026] In semiconductor manufacturing, precise control of film composition, thickness, dopant levels, impurities, critical dimensions, nanostructures, surface roughness, and potential defect levels may be crucial for optimizing the manufacturing process. X-ray metrology techniques may provide valuable data for these process control applications.

[0027] X-ray generation devices for semiconductor metrology may require specific performance characteristics. For example, a small spot size of 50 micrometers or less may be desirable, with minimal scatter outside the measurement spot. This level of precision may help prevent signal contamination from structures outside the intended measurement area.

[0028] Efficient x-ray generation and heat management may be important considerations in the design of x-ray generation devices for semiconductor metrology applications. The conversion of electron beam energy into x-rays typically produces a significant amount of heat, which may need to be effectively managed to maintain device performance and longevity.

[0029] Key components of an x-ray generation device may include an anode for converting an electron beam into x-rays, a substrate for heat dissipation, and a cooling system. The design and optimization of these components may contribute to the overall efficiency and performance of the x-ray generation device in semiconductor metrology applications.

[0030] An example of a combination of an anode and a diamond substrate is illustrated in US patent 7359487 titled DIAMOND ANODE which is incorporated herein by reference. For example - the anode and the diamond substrate may be bonded using one or more metal carbide layers formed between the anode and the diamond substrate. Yet for another example a metal carbide skeleton cemented diamond material may be provided.

[0031] According to an embodiment the cooling of the diamond substrate is a dry cooling and does not include forming channels within the diamond surface - thereby reducing the complexity of the solution.

[0032] The x-ray generation device 30 may include an anode 40 configured to convert an electron beam 33 to an x-ray beam 24. In some cases, the anode 40 may be a thin film deposited on a substrate. The anode 40 may include various materials selected to produce x-rays of desired energies. These materials may include aluminum, chromium, silver, carbon, graphitized carbon, HOPG carbon, neodymium, gadolinium, terbium, tungsten, platinum, lead, and diamond. According to an embodiment, using materials such as silver and chromium having larger Z and melting point than aluminum may not include a cooling system as illustrated in the application.

[0033] The thickness of the anode 40 may be an important parameter affecting x-ray generation efficiency. In some implementations, the anode 40 may have a thickness between 0.5 microns and 5 microns.

[0034] According to an embodiment the anode thickness should slightly exceed the penetration depth of the electron beam - - for example not exceed the penetration depth by a factor of 1.2, and the like.

[0035] The relationship between anode thickness and x-ray flux may be illustrated by a thickness relationship graph 62, as shown in FIG. 3. This graph may demonstrate that from a certain thickness of anode 40, there may be a decline in the x-ray flux generated by the anode 40, with lower electron beam energies potentially associated with higher x-ray flux peaks.

[0036] When the electron beam 33 strikes the anode 40, it may interact with the anode material to produce x-rays through two primary mechanisms: characteristic x-ray emission and bremsstrahlung radiation. Characteristic x-rays are produced when electrons from the beam knock out inner shell electrons from atoms in the anode material, causing electrons from higher energy levels to fill the vacancies and release x-rays with specific energies characteristic of the anode material. Bremsstrahlung radiation, on the other hand, results from the deceleration of electrons as they pass through the anode material, producing a continuous spectrum of x-ray energies.

[0037] In some implementations, the x-ray generation device 30 may include a monochromator crystal to select and focus characteristic x-rays onto a wafer for material analysis. This may allow for the isolation of specific x-ray energies suitable for particular metrology applications.

[0038] Heat management may be a consideration in anode design. In some cases, the anode 40 may be brazed onto a cooling block to remove heat generated during the x-ray production process. This may help prevent melting or ablation of the anode material, which could reduce x-ray output and shorten the anode's lifespan.

[0039] To further manage heat and maintain consistent x-ray output, the anode spot where the electron beam 33 strikes may be moved to a fresh location periodically. In some implementations, this movement may occur every 3 minutes to prevent ablation and diminished x-ray output at any single location on the anode 40. According to an embodiment such a movement is not necessitated as the thermal conductivity of the diamond surface is dramatically increased (due to the cooling of the diamond substrate)and due to lower thickness and other anode related parameters that are selected to prevent the movement.

[0040] The choice of anode material and thickness may depend on various factors, including the desired x-ray energy, the electron beam energy and current, and the specific requirements of the metrology application. Optimization of these anode-related parameters may contribute to the overall efficiency and performance of the x-ray generation device 30 in semiconductor metrology applications.

[0041] The x-ray generation device 30 may further include an electron beam source 31 configured to generate an electron beam 33. The electron beam source 31 may be positioned to direct the electron beam 33 toward the anode 40, as illustrated in FIG. 6. In some cases, the electron beam source 31 may be configured to generate the electron beam 33 with an energy between 1 keV and 20 keV.

[0042] The characteristics of the electron beam 33 may significantly affect the x-ray generation process and the performance of the anode 40. These characteristics may include the electron beam energy, current, and profile. The relationships between these parameters and x-ray generation may be illustrated in the current relationship graph 64 and the thickness relationship graph 62 , as shown in FIG. 3 and FIG. 4.

[0043] In some implementations, the electron beam source 31 may be configured to generate the electron beam 33 with a flat- top profile. This profile may provide a more uniform power loading across the anode 40, which may help to prevent localized heating and extend the lifespan of the anode 40. In contrast, a super-Gaussian profile with a high peak at the center may cause a concentration of heat at the center of the anode 40, potentially leading to faster ablation.

[0044] The current relationship graph 64 may demonstrate how x-ray flux varies with electron beam current at different electron beam energies. From a certain electron beam current, there may be a decline in the x-ray flux generated by the anode 40, with lower electron beam energies potentially associated with higher x-ray flux peaks.

[0045] The intensity of a characteristic x-ray line, such as a K-line, may be related to the electron beam parameters according to the following equation: i = Bi(y - vk

[0046] Where I may represent the intensity of the K-line output, B may be a proportionality constant, i may represent the beam current, Vk may represent the excitation voltage for that line, V may represent the electron energy, and n may be approximately one and a half.

[0047] This relationship may suggest that increasing the electron beam current or energy may lead to an increase in x-ray intensity. However, the thickness relationship graph 62 may indicate that as the electron energy increases, the penetration depth into the anode 40 may also increase. This increased penetration depth may result in greater attenuation of the generated x-rays before they can exit the anode 40, potentially limiting the increase in x-ray output.

[0048] The thermal conductivity graph 66 illustrates the relationship between the temperature of the diamond substrate and its thermal conductivity.

[0049] By carefully selecting and controlling these electron beam parameters, the x- ray generation device 30 may be optimized for specific metrology applications in semiconductor manufacturing processes. The relationships between these parameters may be considered when designing and operating the x-ray generation device 30 to achieve the desired x-ray output while maintaining the longevity and performance of the anode 40.

[0050] The x-ray generation device 30 may include a diamond substrate 44 in thermal contact with the anode 40. The diamond substrate 44 may be configured to absorb heat generated in the anode 40 during the x-ray generation process. FIG. 6 illustrates the diamond substrate 44 positioned beneath the anode 40 in the x-ray generation device 30.

[0051] In some cases, the diamond substrate 44 may include boron-doped diamond. Boron-doped diamond may exhibit exceptional thermal conductivity properties, particularly at low temperatures. The thermal conductivity of the diamond substrate 44 may vary significantly with temperature.

[0052] At room temperature (approximately 20 degrees Celsius), the thermal conductivity of boron-doped diamond may be around 1000 W / mK. However, as the temperature of the diamond substrate 44 decreases, its thermal conductivity may increase substantially. In some implementations, when the diamond substrate 44 is cooled to atemperature between -80 degrees Celsius and -90 degrees Celsius, the thermal conductivity may reach approximately 3750 W / mK.

[0053] The relationship between temperature and thermal conductivity of the diamond substrate 44 may be an important consideration in the design and operation of the x-ray generation device 30. By cooling the diamond substrate 44 to sub-zero temperatures, the heat dissipation capabilities of the x-ray generation device 30 may be significantly enhanced.

[0054] The temperature of the diamond substrate 44 may be considered as one of the anode-related parameters in the design and optimization of the x-ray generation device 30. In some cases, the diamond substrate cooling temperature may be selected to achieve a specific thermal conductivity. For example, a cooling temperature between -80 degrees Celsius and -90 degrees Celsius may be chosen to achieve a thermal conductivity of approximately 3750 W / mK for a boron-doped diamond substrate 44.

[0055] The high thermal conductivity of the diamond substrate 44 at low temperatures may allow for more efficient heat dissipation from the anode 40. This enhanced heat management may potentially enable higher electron beam currents or energies to be used, which may lead to increased x-ray flux without causing damage to the anode 40.

[0056] In some implementations, the diamond substrate 44 may act as a heat spreader, rapidly conducting heat away from the localized area where the electron beam 33 strikes the anode 40. This heat spreading effect may help to prevent hot spots on the anode 40 that could lead to premature degradation or failure.

[0057] The use of a diamond substrate 44 with high thermal conductivity may contribute to the overall performance and longevity of the x-ray generation device 30. By efficiently managing heat generated during the x-ray production process, the diamond substrate 44 may help to maintain consistent x-ray output and extend the operational lifetime of the anode 40.

[0058] The x-ray generation device 30 may further include a cooling system 48 configured to cool the diamond substrate 44 to a temperature below -60 degrees Celsius. FIG. 6 illustrates the cooling system 48 positioned beneath the diamond substrate 44 in the x-ray generation device 30.

[0059] The cooling system 48 assists in maintaining the diamond substrate 44 at subzero temperatures, which may significantly enhance the thermal conductivity of the diamond substrate 44. As previously discussed, the thermal conductivity of the diamond substrate 44, particularly when composed of boron-doped diamond, may increase substantially at lower temperatures.

[0060] In some cases, the cooling system 48 may be configured to cool the diamond substrate 44 to a temperature between -80 degrees Celsius and -90 degrees Celsius. At these low temperatures, the thermal conductivity of the boron-doped diamond substrate 44 may reach approximately 3750 W / mK, which may be significantly higher than its thermal conductivity at room temperature.

[0061] The cooling system 48 may employ various cooling mechanisms to achieve and maintain these low temperatures. In some implementations, the cooling system 48 may use cryogenic cooling techniques, such as liquid nitrogen or helium cooling. In other cases, the cooling system 48 may utilize thermoelectric cooling devices or multi-stage cooling systems to reach the desired sub-zero temperatures.

[0062] Maintaining the diamond substrate 44 at such low temperatures may provide several benefits for the x-ray generation device 30. The enhanced thermal conductivity at these temperatures may allow for more efficient heat dissipation from the anode 40, potentially enabling higher electron beam 33 currents or energies to be used without causing damage to the anode 40.

[0063] The cooling system 48 may work in conjunction with the diamond substrate 44 to manage the heat generated during the x-ray production process. As the electron beam 33 strikes the anode 40, heat may be rapidly conducted through the diamond substrate 44 and efficiently removed by the cooling system 48. This efficient heat management may help to maintain consistent x-ray beam 24 output and extend the operational lifetime of the anode 40.

[0064] In some implementations, the cooling system 48 may be designed to provide precise temperature control, allowing for optimization of the diamond substrate 44 temperature based on specific operational requirements or desired thermal conductivity levels. This temperature control may be considered as one of the anode-related parameters in the design and operation of the x-ray generation device 30.

[0065] The cooling system 48, in combination with the highly conductive diamond substrate 44, may contribute to the overall performance and reliability of the x-ray generation device 30. By effectively managing heat and maintaining the diamond substrate 44 at optimal low temperatures, the cooling system 48 may help to enable high- throughput x-ray generation for advanced semiconductor metrology applications.

[0066] The x-ray generation process in the x-ray generation device 30 may involve the interaction between the electron beam 33 and the anode 40, resulting in the emission of the x-ray beam 24. This process may produce two types of x-rays: characteristic x-rays and bremsstrahlung radiation.

[0067] When the electron beam 33 strikes the anode 40, the electrons may interact with the atoms in the anode material. In some cases, these interactions may occur within an interaction volume 22, as illustrated in FIG. 1 and FIG. 2. The interaction volume 22 may have a characteristic pear shape that extends deeper into the anode 40 as the energy of the electron beam 33 increases.

[0068] Characteristic x-rays may be produced when electrons from the electron beam 33 knock out inner shell electrons from atoms in the anode 40. This process may create vacancies in the inner electron shells. As electrons from higher energy levels fill these vacancies, x-rays with specific energies characteristic of the anode material may be emitted. The energy of these characteristic x-rays may depend on the atomic structure of the anode material.

[0069] In addition to characteristic x-rays, the interaction between the electron beam 33 and the anode 40 may also produce bremsstrahlung radiation. Bremsstrahlung, which means "braking radiation" in German, may occur when electrons from the electron beam 33 decelerate as they pass through the electric field of the atomic nuclei in the anode material. This deceleration may cause the electrons to lose energy, which may be emitted as x-rays.

[0070] The bremsstrahlung radiation may form a continuous spectrum of x-ray energies, as illustrated by a bremsstrahlung spectrum 10 shown in FIG. 1 and FIG. 2. The bremsstrahlung spectrum 10 may represent the distribution of x-ray intensities across different energies. In some cases, the maximum energy of the bremsstrahlung x-rays may be equal to the energy of the incident electrons in the electron beam 33.

[0071] The efficiency of x-ray production may depend on various factors, including the energy of the electron beam 33, the atomic number of the anode material, and the thickness of the anode 40. The thickness relationship graph 62 may illustrate how the x- ray flux varies with anode thickness at different electron beam energies.

[0072] As the electrons from the electron beam 33 penetrate deeper into the anode 40, they may lose energy through various interactions. This energy loss may affect the production of both characteristic x-rays and bremsstrahlung radiation. X-rays generated deeper within the interaction volume 22 may be more likely to be absorbed by the anode material before they can escape and contribute to the x-ray beam 24.

[0073] The current relationship graph 64 may demonstrate how the x-ray flux varies with electron beam current at different electron beam energies. Increasing the current of the electron beam 33 may generally lead to an increase in x-ray production. However, there may be a point of diminishing returns where further increases in current may not significantly improve x-ray output.

[0074] The beam profile graph 66 may illustrate the distribution of electron beam intensity across the beam profile. The shape of this profile may affect the distribution of x-ray production across the surface of the anode 40. In some cases, a flat-top profile for the electron beam 33 may be preferred to provide more uniform x-ray production and heat distribution across the anode 40.

[0075] Heat generation may be a significant byproduct of the x-ray generation process. A large portion of the energy from the electron beam 33 may be converted into heat within the anode 40. The diamond substrate 44 may play a crucial role in dissipating this heat. The cooling system 48 may further assist in maintaining the temperature of the diamond substrate 44 at optimal levels for efficient heat dissipation.

[0076] The x-ray beam 24 emerging from the anode 40 may consist of both characteristic x-rays and bremsstrahlung radiation. In some applications, specific x-ray energies may be selected from this beam using additional optical components, such as monochromators or filters, which may not be shown in FIG. 6.

[0077] Understanding the x-ray generation process and the factors affecting x-ray production may be important for optimizing the performance of the x-ray generation device 30 in various applications, including semiconductor metrology.

[0078] The x-ray generation device 30 may integrate various components to optimize x-ray flux while effectively managing heat dissipation. FIG. 6 illustrates the arrangement and interaction of these components within the x-ray generation device 30.

[0079] The electron beam source 31 may generate the electron beam 33, which may be directed towards the anode 40. When the electron beam 33 strikes the anode 40, x-rays may be produced through characteristic emission and bremsstrahlung radiation, as previously described. The interaction between the electron beam 33 and the anode 40 may occur within the interaction volume 22, which may vary in size and shape depending on the electron beam energy and anode material properties.

[0080] The anode 40 may be designed to optimize x-ray production based on the relationships illustrated in the thickness relationship graph 62, the current relationship graph 64, and the beam profile graph 66. The thickness of the anode 40 may be selected to maximize x-ray flux while considering the penetration depth of the electron beam 33. In some cases, the anode thickness may be between 0.5 microns and 5 microns, depending on the specific requirements of the x-ray generation application.

[0081] The diamond substrate 44 may be in thermal contact with the anode 40 and may play a crucial role in heat management. The high thermal conductivity of the diamond substrate 44, particularly at low temperatures, may allow for efficient heat dissipation from the anode 40. This heat dissipation may help prevent anode damage and maintain consistent x-ray output.

[0082] The cooling system 48 may work in conjunction with the diamond substrate 44 to maintain optimal operating temperatures. By cooling the diamond substrate 44 to temperatures below -60 degrees Celsius, the cooling system 48 may significantly enhance the thermal conductivity of the diamond substrate 44. This enhanced thermal conductivity may allow for more efficient heat removal from the anode 40, potentially enabling higher electron beam currents or energies to be used without causing damage to the anode 40.

[0083] The integration of these components may allow the x-ray generation device 30 to produce the x-ray beam 24 with optimized flux while effectively managing heat. The electron beam source 31 may be adjusted to provide the desired electron beam energy and current, based on the relationships shown in the current relationship graph 64.The beam profile of the electron beam 33 may be optimized, as illustrated in the beam profile graph 66, to provide uniform power loading across the anode 40.

[0084] In some cases, the operation of the x-ray generation device 30 may follow a method 100 for generating x-rays, as illustrated in FIG. 7. The method 100 may include a step 104 of converting, by the anode 40, the electron beam 33 that illuminates the anode 40 to the x-ray beam 24. In parallel with step 104, a step 108 may involve absorbing, by the diamond substrate 44, heat generated in the anode 40 as a result of the illumination of the anode 40 with the electron beam 33. A step 110 may involve cooling the diamond substrate 44 to a sub-zero temperature that may be below minus sixty degrees Celsius.

[0085] The design and optimization of the x-ray generation device 30 may follow a method 120 for designing a device for generating x-rays, as illustrated in FIG. 8. The method 120 may begin with a step 122 of obtaining information regarding one or more relationships between one or more anode related parameters. These relationships may include those illustrated in the thickness relationship graph 62, the current relationship graph 64, and the beam profile graph 66. Following step 122, a step 124 may involve designing the device using at least one anode related parameter, based on the one or more relationships obtained in the previous step.

[0086] By integrating these components and following these methods, the x-ray generation device 30 may be capable of producing a high-flux x-ray beam 24 while effectively managing heat dissipation. This integration may allow for optimized performance in various applications, including semiconductor metrology, where high- throughput and precise x-ray generation may be required.

[0087] The design of the x-ray generation device 30 may involve careful consideration of various parameters and their relationships to optimize performance. In some cases, a method 120 for designing a device for generating x-rays may be employed, as illustrated in FIG. 7, FIG. 8.

[0088] The method 120 may include a step 122 of obtaining information regarding one or more relationships between one or more anode related parameters. These relationships may be represented by the thickness relationship graph 62, the current relationship graph 64, and the beam profile graph 66, as shown in FIG. 3, FIG. 4, and FIG. 5.

[0089] Following step 122, the method 120 may include a step 124 of designing the device using at least one anode related parameter based on the one or more relationships obtained in the previous step. This design process may involve selecting various parameters to optimize the performance of the x-ray generation device 30.

[0090] In some cases, designing the x-ray generation device 30 may involve selecting an anode thickness between 0.5 microns and 5 microns. The selection of the anode thickness may be based on a relationship between x-ray flux and anode thickness at different electron beam energies, as illustrated in the thickness relationship graph 62. This relationship may show how the x-ray flux varies with anode thickness for different electron beam energies, allowing for the selection of an optimal thickness to maximize x- ray output.

[0091] The design process may also include selecting an electron beam energy between 1 keV and 20 keV. This selection may be based on the relationship between x- ray flux and anode thickness, as shown in the thickness relationship graph 62. The electron beam energy may affect the penetration depth of electrons into the anode and the efficiency of x-ray production.

[0092] Another consideration in designing the x-ray generation device 30 may be the selection of an electron beam profile that provides a uniform power loading across the anode. The beam profile graph 66 may illustrate different electron beam profiles and their impact on power distribution. A uniform power loading may help prevent localized heating and extend the lifespan of the anode.

[0093] The design process may further involve selecting a diamond substrate cooling temperature between -80 degrees Celsius and -90 degrees Celsius. This temperature range may be chosen to optimize the thermal conductivity of the diamond substrate, which may enhance heat dissipation from the anode.

[0094] In some cases, the relationships between these parameters may be interdependent. For example, the optimal anode thickness may vary depending on the selected electron beam energy. Similarly, the choice of electron beam profile may affect the required cooling temperature for the diamond substrate.

[0095] The current relationship graph 64 may provide additional information for optimizing the x-ray generation device 30. This graph may show how x-ray flux varieswith electron beam current at different electron beam energies, which may be considered when selecting the operating parameters for the electron beam source 31.

[0096] By carefully considering these relationships and selecting appropriate parameters, the x-ray generation device 30 may be designed to produce an optimized x- ray beam 24 while effectively managing heat dissipation through the diamond substrate and the cooling system 48.

[0097] Any reference to “may be” should also refer to “may not be”.

[0098] In the foregoing detailed description, numerous specific details are set forth to provide a thorough understanding of the one or more embodiments of the disclosure.However, it will be understood by those skilled in the art that the present one or more embodiments of the disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present one or more embodiments of the disclosure.

[0099] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0100] Because the illustrated embodiments of the disclosure may for the most part, be implemented using electron optic components and circuits known to those skilled in the art, details will not be explained in any greater extent than that considered necessary as illustrated above, for the understanding and appreciation of the underlying concepts of the present one or more embodiments of the disclosure and in order not to obfuscate or distract from the teachings of the present one or more embodiments of the disclosure.

[0101] Any reference in the specification to a method should be applied mutatis mutandis to a method capable of executing the method.

[0102] Any reference in the specification to a method and any other component should be applied mutatis mutandis to a method that may be executed by a method .

[0103] Any combination of any module or unit listed in any of the figures, any part of the specification and / or any claims may be provided. Especially any combination of any claimed feature may be provided.

[0104] In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the appended claims.

[0105] Any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

[0106] Any reference to “consisting”, “having” and / or “including” should be applied mutatis mutandis to “consisting” and / or “consisting essentially of’.

[0107] Furthermore, those skilled in the art will recognize that boundaries between the above described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

[0108] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0109] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds truefor the use of definite articles. Unless stated otherwise, terms such as “first" and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0110] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.[OHl] It is appreciated that various features of the embodiments of the disclosure which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the embodiments of the disclosure which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub-combination.

[0112] It will be appreciated by persons skilled in the art that the embodiments of the disclosure are not limited by what has been particularly shown and described hereinabove. Rather, the scope of the embodiments of the disclosure is defined by the appended claims and equivalents thereof.

Claims

CLAIMS1. A device for generating x-rays, comprising: an anode configured to convert an electron beam to an x-ray beam; a diamond substrate in thermal contact with the anode and configured to absorb heat generated in the anode; and a cooling system configured to cool the diamond substrate to a temperature below -60 degrees Celsius.

2. The device of claim 1, wherein the anode comprises aluminum.

3. The device of claim 1, wherein the anode has a thickness between 0.5 microns and 5 microns.

4. The device of claim 1, further comprising an electron beam source configured to generate the electron beam with an energy between 1 keV and 20 keV.

5. The device of claim 4, wherein the electron beam source is configured to generate the electron beam with a flat-top profile.

6. The device of claim 1, wherein the cooling system is configured to cool the diamond substrate to a temperature between -80 degrees Celsius and -90 degrees Celsius.

7. The device of claim 6, wherein the diamond substrate comprises boron-doped diamond having a thermal conductivity of approximately 3750 W / mK at the temperature between -80 degrees Celsius and -90 degrees Celsius.

8. A method for generating x-rays, comprising: converting, by an anode, an electron beam that illuminates the anode to an x-ray beam; absorbing, by a diamond substrate in thermal contact with the anode, heat generated in the anode as a result of the illumination of the anode with the electron beam; and cooling the diamond substrate to a temperature below -60 degrees Celsius.

9. The method of claim 8, wherein the anode comprises Aluminum.

10. The method of claim 8, wherein the anode has a thickness between 0.5 microns and 5 microns.

11. The method of claim 8, wherein the electron beam has an energy between 1 keV and 20 keV.

12. The method of claim 11, wherein the electron beam has a flat-top profile.

13. The method of claim 8, wherein cooling the diamond substrate comprises cooling the diamond substrate to a temperature between -80 degrees Celsius and -90 degrees Celsius.

14. The method of claim 13, wherein the diamond substrate comprises boron-doped diamond having a thermal conductivity of approximately 3750 W / mK at the temperature between -80 degrees Celsius and -90 degrees Celsius.

15. A method for designing a device for generating x-rays, comprising:obtaining information regarding one or more relationships between one or more anode related parameters; and designing the device using at least one anode related parameter based on the one or more relationships, wherein the device comprises an anode configured to convert an electron beam to an x-ray beam, and a diamond substrate in thermal contact with the anode and configured to be cooled to a temperature below -60 degrees Celsius.

16. The method of claim 15, wherein the one or more anode related parameters include at least one of: electron beam energy, electron beam current, electron beam profile, anode thickness, anode material, and diamond substrate temperature.

17. The method of claim 16, wherein designing the device comprises selecting an anode thickness between 0.5 microns and 5 microns based on a relationship between x-ray flux and anode thickness at different electron beam energies.

18. The method of claim 17, wherein designing the device further comprises selecting an electron beam energy between 1 keV and 20 keV based on the relationship between x-ray flux and anode thickness.

19. The method of claim 18, wherein designing the device further comprises selecting an electron beam profile that provides a uniform power loading across the anode.

20. The method of claim 19, wherein designing the device further comprises selecting a diamond substrate cooling temperature between -80 degrees Celsius and -90 degrees Celsius to achieve a thermal conductivity of approximately 3750 W / mK for a boron-doped diamond substrate.

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