Dual-source X-ray inspection system and method

Abstract

To present X-ray inspection systems and methods.SOLUTION: An X-ray inspection system 100 according to the present invention comprises at least two X-ray sources 102 and 104 positioned and oriented at a selected angle with respect to an inspection surface to provide a common illumination spot 122 on an inspection surface of a sample 120, and thereby provides inspection of a common area of the sample with at least one of increased illumination intensity or two or more different illumination characteristics while reducing navigation and alignment processing.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure is in the field of X-ray inspection of samples, and more particularly relates to inspections using two or more X-ray radiation sources.

Background Art

[0002] Inspection of fabricated samples is an important part of the manufacturing process. Various manufactured articles can be inspected for structural parameters, selected patterns, and material composition. With the progress of technology, manufactured articles are becoming smaller and the required inspection accuracy is increasing.

[0003] X-ray fluorescence (XRF) inspection provides a non-destructive technique for detecting the elemental composition of materials. In XRF inspection, fluorescence caused by excitation of a sample material by X-ray radiation provided by an X-ray source is utilized. Atoms of different elements produce characteristic fluorescence emissions unique to each element, enabling detection of the material composition of the sample. Energy dispersive X-ray fluorescence (EDXRF) is one of several XRF techniques commonly used in elemental analysis applications and enables detection of various elements present in a sample material.

[0004] Patent Document 1 provides a method and apparatus for inspecting a semiconductor wafer for abnormalities by accurately measuring the elemental concentration in a target region. The apparatus includes an X-ray imaging subsystem for measuring the elemental composition in a target region of a semiconductor wafer. The apparatus further includes an EDXRF subsystem for measuring the elemental concentration in a target region of the semiconductor wafer. The elemental concentration may be calibrated by correlating an elemental concentration measurement obtained using an X-ray imaging system for the target region with an elemental concentration measurement obtained using an EDXRF subsystem for the target region to receive an enhanced accurate elemental concentration measurement for the target region of the semiconductor wafer.

[0005] Patent Document 2 provides an X-ray optical system comprising an X-ray source that emits X-rays, a first optical element that adjusts the X-rays to form two beams, and at least a second optical element that further adjusts at least one of the two beams from the first optical element. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Publication No. 10,697,908 [Patent Document 2] U.S. Publication No. 8,249,220 [Overview of the project]

[0007] The bandwidth and energy range of the X-ray emission used in XRF can affect noise associated with reflected and / or scattered emission portions that mask the fluorescence response. For this purpose, complete inspection of fabricated samples often requires inspection using two or more different inspection conditions. This may require inspection of the sample using two inspection systems or replacement of inspection units within an existing inspection system. This disclosure provides an inspection system configuration utilizing two or more inspection units, both of which are positioned over the sample area of ​​the inspection system and configured to illuminate a common spot on the sample. This configuration enables several operating modes, including simultaneous illumination of selected locations on the sample with X-ray emission from two or more X-ray sources, thus increasing the illumination intensity, and / or sequential illumination of selected locations on the sample using first and second X-ray sources having different illumination characteristics. Furthermore, aligning two or more inspection units to a common illumination spot simplifies the navigation and alignment of output data to the sample configuration.

[0008] The system configurations of this disclosure offer several advantages over the prior art, depending on the relationship between the energy bands of the X-ray sources used in the system. For example, using two or more X-ray sources with similar energy band outputs can increase the illumination flux and therefore the intensity per unit area. Alternatively, using X-ray sources configured to emit X-ray radiation with two or more different illumination characteristics, such as illumination energy (wavelength), based on the use of two or more different X-ray sources, offers various additional advantages and enables unique applications.

[0009] Patent applications IL301287 and US18 / 142161, assigned to the assignee of this application, describe a sample inspection system comprising at least first and second inspection units positioned above a sample area. At least each of the first and second inspection units comprises at least one X-ray emission source and respective detector configurations and is configured for X-ray fluorescence inspection of a sample. The first and second X-ray inspection units provide first and second inspection characteristics that differ in at least one of the bandwidth of the emitted X-ray energy, the energy of the emitted X-rays, and the spot size of the X-ray beam generated on the sample.

[0010] The use of two or more X-ray sources within a sample inspection system can improve inspection accuracy and increase the signal-to-noise ratio for detecting selected elements. However, further scanning and alignment of characteristic locations on the sample may extend the inspection time.

[0011] This disclosure provides an X-ray inspection system comprising two or more X-ray sources positioned and oriented to illuminate a common area on a sample. The two or more X-ray sources may operate simultaneously to provide enhanced illumination intensity, enabling detection or relatively low signal data. In addition, or instead, the two or more X-ray sources can be operated sequentially to provide scanning with two or more illumination characteristics, eliminating the need for repeated alignment and thus reducing inspection time.

[0012] Furthermore, two or more X-ray inspection units may operate using a common detection configuration. More specifically, since the X-ray emission from at least the first and second X-ray sources is directed to a commonly selected illumination spot on the sample, a common detection configuration can be used to collect fluorescence emission from the sample. This configuration allows for simplification of system construction and cost.

[0013] Therefore, according to a broader aspect, this disclosure relates to an X-ray inspection system, The present invention provides an X-ray inspection system comprising at least two X-ray sources positioned and oriented at a selected angle relative to the inspection surface to provide a common illumination spot on the inspection surface.

[0014] According to some embodiments, the inspection system may further include a sample mount for positioning the sample to be inspected, the sample mount defining the inspection surface, and at least two X-ray sources positioned at a selected angle with respect to the inspection surface.

[0015] According to some embodiments, at least two X-ray sources may be positioned or arranged equidistant from a common illumination spot.

[0016] According to some embodiments, at least two X-ray sources may be positioned or arranged symmetrically with respect to the normal to the inspection surface that intersects the inspection surface at a common illumination spot.

[0017] According to some embodiments, at least two X-ray sources may be positioned or arranged at at least first and second different distances from a common illumination spot.

[0018] According to some embodiments, at least two X-ray sources may be configured to emit X-ray radiation formed from one or more discrete energy bands.

[0019] According to some embodiments, at least two X-ray sources may be multicolor X-ray sources.

[0020] According to some embodiments, at least two X-ray sources may be configured to emit radiation with similar energy characteristics.

[0021] According to some embodiments, the inspection system may further include an optical microscope positioned between at least two X-ray sources, the optical microscope being aligned with respect to the normal to the inspection surface and oriented to image a common illumination spot on the inspection surface.

[0022] According to some embodiments, the optical microscope may be oriented to image the illumination spot at an angle perpendicular to the inspection surface.

[0023] According to some embodiments, the inspection system may include two X-ray sources, the two X-ray sources being symmetrically positioned and oriented on two opposite sides of a virtual plane perpendicular to the inspection surface.

[0024] According to some embodiments, the inspection system may include three X-ray sources positioned and oriented with triangular symmetry with respect to an axis perpendicular to the inspection surface and intersecting the inspection surface at a common illumination spot.

[0025] According to some embodiments, at least two X-ray sources may be positioned at two or more different angular orientations and distances while being oriented to illuminate a common illumination spot on the inspection surface.

[0026] According to some embodiments, the inspection system may further include a detector configuration including at least one X-ray detector configured to collect a fluorescence response from a sample in response to illumination using at least one of the at least two X-ray sources.

[0027] According to some embodiments, the detector configuration can include at least two detectors, each configured to collect X-ray fluorescence emission from a sample in response to irradiation by any one of at least two X-ray sources.

[0028] According to some embodiments, the detector configuration can include at least one silicon drift detector.

[0029] According to another broad aspect, the present disclosure is a method for use in sample inspection, comprising: (a) providing an inspection system having two or more X-ray sources oriented to illuminate a common illumination spot; (b) placing a sample on an inspection surface for inspection; (c) shifting the common illumination spot relative to the sample to scan the sample using at least one of the two or more X-ray sources; (d) providing output data indicative of signals collected from one or more regions of the sample.

[0030] According to some embodiments, the method can further include operating two or more X-ray sources on one or more selected regions of the sample to sequentially illuminate the sample one by one using the two or more X-ray sources, and collecting signals regarding the selected positions and the selected X-ray sources, thereby scanning the sample using the two or more X-ray sources.

[0031] According to some embodiments, the method can include scanning the sample using a first X-ray source of the two or more X-ray sources, and operating one or more additional X-ray sources of the two or more X-ray sources to scan selected regions of the sample according to one or more region parameters.

[0032] According to some embodiments, the method may further include operating at least two or more X-ray sources to illuminate one or more selected areas of a sample, thereby enhancing illumination intensity and signal acquisition.

[0033] In yet another broader aspect, the Disclosure provides a machine-readable program storage device that tangibly embodies a program of machine-executable instructions embedded in a non-temporary computer-readable medium for use in sample testing, the method (e) In response to an input signal indicating a sample placed on the inspection surface, (f) Operating the sample mount to shift the sample within the scanning pattern in order to inspect one or more regions of the sample, (g) For each scanning position, two or more X-ray sources are operated to sequentially illuminate the sample one by one using two or more X-ray sources, and signals related to the selected position and selected X-ray source are collected. (h) Includes generating output data indicating that the sample is scanned using two or more X-ray sources.

[0034] In a more broad embodiment, the Disclosure relates to a computer program product including a computer-readable medium incorporating computer-readable program code for use in sample testing, A computer-readable program code to cause the computer to respond to instructions on the sample placed on the inspection surface, The computer has computer-readable program code to operate the sample mount to shift the sample within a scanning pattern and inspect one or more regions of the sample, Computer-readable program code for causing a computer to selectively operate one or more of two or more selected X-ray sources to illuminate a common illumination spot on a sample and to collect signals related to the selected location and selected X-ray sources, The present invention provides a computer program product that includes computer-readable program code for causing a computer to generate output data indicating that a sample is scanned using two or more X-ray sources. [Brief explanation of the drawing]

[0035] Embodiments are described herein, only as non-limiting examples, with reference to the accompanying drawings, in order to better understand the subject matter disclosed herein and to illustrate how it may actually be carried out.

[0036] [Figure 1A] This disclosure schematically illustrates inspection systems utilizing two or more X-ray sources according to several embodiments. Figure 1A shows generally similar X-ray sources. [Figure 1B] This disclosure schematically illustrates inspection systems utilizing two or more X-ray sources according to several embodiments. Figure 1B shows the use of different X-ray sources. [Figure 2] The following schematic examples illustrate control units for use in inspection systems according to several embodiments of this disclosure. [Figure 3] Sketches of inspection systems according to several embodiments of this disclosure are shown. [Figure 4] The following are examples of configuration parameters in inspection systems according to several embodiments of this disclosure. [Figure 5] This is a block diagram illustrating the inspection operation according to some embodiments of the present disclosure. [Figure 6] Further inspection methods according to some embodiments of this disclosure are illustrated in block diagrams. [Figure 7] Inspection methods according to some embodiments of this disclosure are illustrated in a separate block diagram. [Figure 8] A block diagram illustrates an inspection method utilizing simultaneous illumination using a first and second X-ray source, according to several embodiments of this disclosure. [Modes for carrying out the invention]

[0037] As described above, this disclosure provides an X-ray inspection system comprising at least two X-ray sources. The at least two X-ray sources are positioned and oriented at a selected angle with respect to the inspection surface to illuminate a common illumination spot on the inspection surface on which the sample is generally placed.

[0038] Refer to Figures 1A and 1B, which show two exemplary configurations of inspection system 100 according to some embodiments of the present disclosure. Figure 1A shows inspection system 100 including two substantially similar X-ray sources 102 and 104, and Figure 1B shows inspection system 100 including two X-ray sources having at least one different X-ray emission characteristic. Note that X-ray sources 102 and 104 are shown in Figure 1B as having different sizes to emphasize that these X-ray sources provide illumination with different characteristics. However, generally speaking, the actual size and shape factors of X-ray sources 102 and 104 may be similar or different.

[0039] Figure 1A schematically shows an X-ray inspection system 100 including a first X-ray source 102, a second X-ray source 104, and a sample mount 110. Generally, the first and second X-ray sources may be mounted on a common beam 142 located on a frame 144. Furthermore, the inspection system 100 may include a detector configuration 106 including one or more detectors (e.g., detectors 106a and 106b) and an optional optical microscope 108. Figure 1B shows an inspection system 100 utilizing the first X-ray source 102 and the second X-ray source 104a, where these X-ray sources are selected to provide different X-ray emissions in at least one of the radiant energy ranges or specific radiant energies to enable inspections with first and second different characteristics.

[0040] The first X-ray source 102 and the second X-ray sources 104, 104a may each include a radiation source and their respective optical systems for directing the emitted radiation of the first and second beams. Furthermore, the first and second X-ray sources may be configured to provide similar beam parameters, such as radiation energy (wavelength), to increase the irradiation intensity. Alternatively, as illustrated in Figure 1B, different X-ray sources may be used to provide radiation with different energy ranges and / or peak energies, enabling inspections with different X-ray illumination characteristics.

[0041] Generally, the X-ray sources (102, 104, 104a) are positioned on the beam 142 and may be mounted on a common connector connected to the system structure 144. Furthermore, the X-ray sources (102, 104, 104a) are oriented to direct the emitted radiation toward the common illumination spot 122. In this regard, the inspection system 100 is adapted for inspection of a sample 120 positioned on a sample mount 110. The position of the sample mount defines the inspection surface associated with the position of the sample 120. This provides inspection of the area of ​​the sample 120 located toward the illumination spot 122 by the appropriate position of the sample mount 110, while the X-ray sources (102, 104, 104a) are oriented to emit radiation toward the common illumination spot 122.

[0042] Typically, in various inspection systems, each radiation source is associated with one or more detectors. The inspection system 100 of this disclosure utilizes one or more detectors, exemplified by detectors 106a and 106b, which are commonly used for detecting a sample response to illumination using a first and / or second X-ray source. In this regard, the use of two or more X-ray sources directed to a common illumination spot allows for cost, space, and complexity savings by enabling the use of a common detector configuration shared by the X-ray sources.

[0043] In some examples, the first X-ray source 102 and the second X-ray source 104 may be multicolor X-ray sources.

[0044] In some other examples, the inspection system 100 may also include an optical microscope 108. The optical microscope 108 may be mounted on a common connector attached to the beam 142 and positioned to provide optical imaging of the common illumination spot 122. The optical microscope 108 may be used for inspecting the sample 120 to select appropriate areas where inspection using the first X-ray source 102 and / or the second X-ray source (104, 104a) or both X-ray sources is required.

[0045] The operation of the inspection system can be determined using a control unit directly or indirectly connected to the X-ray sources 102 and 104, detectors 106 and 106a, sample mount 110, and optionally an optical microscope 108. The control unit may be a computer system including one or more processors, memory, and communication modules, and may also include a user interface. In this regard, see Figure 2, which shows a control unit 500. The control unit 500 may be connected to the inspection system 100 using one or more wires or by wireless communication, and is configured to control the operation of various components of the inspection system 100, as will be described in more detail below. The control unit 500 generally includes one or more processor 210 and memory 220 circuits (PMCs). The processor 210 and memory 220 circuits are operably connected to hardware-based I / O 250 and / or a user interface 260 and are configured to provide processing functions for operating the inspection system 100 as described herein. The processor 210 may be configured to execute one or more functional modules in accordance with computer-readable instructions stored in memory 220 or implemented by one or more computer-readable media (e.g., non-temporary computer-readable media). Such functional modules are referred to herein as being included in the PMC. For example, as shown in Figure 2, the PMC may include a mount controller 230 that can be operated to generate and send operation commands to the sample mount (110 in Figures 1A and 1B) to translate the sample by a selected shift in the XY plane and / or to correct the mount height by translation along the Z axis. Furthermore, as illustrated in Figure 2, the PMC may include an X-ray source controller 240 that can be operated and configured to generate and send operation commands to two or more X-ray sources 104, 102 or 104a. Such operation commands may include on or off operation, as well as energy selection for sources to support variations in radiant energy.

[0046] Furthermore, see Figure 3, which shows a first X-ray source 102 and a second X-ray source 104 mounted on a common connector 140 according to some embodiments of the present disclosure. As shown, the first X-ray source 102 and the second X-ray source 104 are mounted in a selected angular orientation, determined according to the height of the X-ray sources relative to the sample mount, in order to direct the emitted X-ray beams toward a common illumination spot. The common connector 140 may also include a mount for a detector configuration including one or more detectors, as exemplified by detectors 106a and 106b, and further include a mount for an optical microscope 108 that positions the microscope above the common illumination spot. It should be noted that, in general, the inspection system may include any selected number of detectors, such as two, three, four, or more. It should also be noted that one advantage of the system of the present disclosure is the use of a common detector configuration associated with the first and second (or more) X-ray sources.

[0047] To simplify the system configuration and provide generally similar illumination conditions for the first and second X-ray sources, the X-ray sources may preferably be positioned in similar angular relationships with respect to the inspection surface defined by the sample mount. This is illustrated in Figure 4, which shows the position and orientation of the first X-ray source 102 and the second X-ray source 104 and the optical microscope 108 according to some embodiments of the present disclosure. As shown, the X-ray sources 102 and 104 are mounted with angular orientations θ1 and θ2, respectively, with respect to the normal of the inspection surface 124, while directing the emitted illumination towards a common illumination spot 122. Typically, the optical microscope 108 may be aligned with the normal to the inspection surface 124 to provide desired optical imaging of the sample and enable the operator to identify selected areas of the sample for inspection.

[0048] In some other embodiments, typically utilizing first and second X-ray sources having different energy ranges, the first and second X-ray sources (e.g., 102 and 104a) may be positioned in an asymmetric configuration to provide different heights across the inspection surface and / or provide that θ1 and θ2 are not equal. This may be used in embodiments utilizing a multicolor first X-ray source 102 and a second X-ray source 104a that provides X-ray emission having illumination in one or more discrete and relatively narrow energy ranges.

[0049] Generally, the first X-ray source 102 and the second X-ray source 104 can be positioned at the same or different distances from the illumination spot. The choice of distance between the X-ray sources may be determined based on both spatial requirements due to the size and shape factors of the different X-ray sources, as well as according to the desired illumination and optical properties. The X-ray sources are typically associated with an optical configuration for shaping the emitted radiation to form an illumination beam, and the beam divergence or collimation level, along with the distance to the illumination spot, affects the size of the illumination spot.

[0050] Generally, the common connector 140 can enable specific alignment of the first and second X-ray sources 102 and 104, allowing for adjustment of their illumination patterns and providing a common illumination spot. Figure 5 illustrates a method for enabling proper alignment of the X-ray sources and optical microscope to a common illumination spot. As shown, the method includes providing a system having two or more X-ray sources 5010 and aligning the X-ray sources to a common illumination spot 5020. Aligning the X-ray sources may include positioning a scintillator unit at a desired illumination spot 5022 and detecting the optical response of the scintillator in response to illumination with X-ray emission from the first and second X-ray sources 5024. Detection of the optical response of the scintillator at the common spot due to illumination by both the first and second X-ray sources provides verification to the common illumination spot 5030.

[0051] A scintillator is an element or material that exhibits scintillation. More specifically, a scintillator emits optical illumination in response to excitation illumination impacting it. Scintillators are often used for radiation detection, and in this specification, they are used for detecting X-ray illumination and locating illumination spots. To determine the precise location of the illumination spot, an X-ray source can be operated sequentially, while an optical microscope can be positioned to perform imaging and optical inspection of the illumination spot, determining its location based on the scintillator's emission.

[0052] The use of scintillators to identify the precise location of the illumination spot formed by each X-ray source enables a simple and reliable technique for aligning the X-ray sources to a common illumination spot. Proper alignment of the X-ray sources to the common illumination spot allows for sample inspection using combined illumination from the X-ray sources to increase illumination intensity. Alternatively, the X-ray sources may be used sequentially, with the first X-ray source used to scan the sample, the first X-ray source being turned off at a selected location, and the second X-ray source being used for inspection of the selected location. This enables combined inspection while simplifying the alignment of the acquired data to sample coordinates.

[0053] In this regard, Figure 6 illustrates an operating method for sample inspection according to some embodiments of the present disclosure. As illustrated in Figure 6, in order to initiate the inspection, a sample for inspection is typically provided within the inspection system.6010 Generally, the sample is placed on a sample mount (110 in Figure 1),6020 and the sample may be held on the sample mount by mechanical clamps and / or using low-pressure mounts. Once the sample is placed, the system may be operable by operating the sample mount to translate to a selected inspection spot.6030 Typically, in some embodiments, the sample may undergo a selected translation shift to determine the sample size and position and to calibrate the alignment data.

[0054] Once the sample mount places the sample at the selected inspection spot, the system operates to illuminate the sample with a first X-ray source, 6040 and collect the fluorescence response from the sample, 6050. The collected fluorescence response is detected by one or more detectors and sent to the control unit to determine the response parameters for the inspected location, 6060. According to the inspection pattern, the system can further operate the control unit to illuminate the same inspection location using a second X-ray source, 6070, collect the fluorescence response, 6080 and determine the response parameters, 6090. After inspecting and determining the parameters for the selected inspection location, the control unit can repeat the inspection process by operating the sample mount to move the sample to the next inspection location, 6100 and illuminating the sample, 6040.

[0055] The inspection technique illustrated in Figure 6 allows inspection of a sample using first and second illumination characteristics, e.g., first and second illumination energy ranges, while simplifying alignment and providing redundant output data, with each selected position being inspected using different illumination characteristics. The operation method illustrated in Figure 6 can be implemented using computer-readable instructions pre-stored in the control unit's memory and executed by a processor, following the operation of providing the sample. Figure 7 illustrates an operation method suitable for implementation as computer-readable instructions executed by one or more processors.

[0056] More specifically, the instruction includes responding to or receiving an instruction message regarding the sample position on the sample mount 7010 and operating the sample mount in a selected scanning pattern 7020. Within the selected scanning pattern, the method includes determining an inspection position associated with a position on the sample to be inspected 7030 and operating a first X-ray source to illuminate an illumination spot on the sample 7040. Generally, a detector configuration operates to collect emission responses from the sample, and a control unit operates to collect response data from the detector configuration 7050. A processor can generally store the collected response data with reference to the inspection position. Furthermore, the processor can operate to determine whether an inspection using a second X-ray source is required at this particular position and proceed to operate a second X-ray source to illuminate the sample 7060, and to determine whether the inspection position is selected for an inspection using a second X-ray source. Similarly, the technique further includes receiving / collecting response emission from the sample 7070 and storing the response data with reference to the inspection position. After completing the inspection of a position on the sample, the processor generates an instruction to the sample mount to shift to the next inspection position according to the selected scanning pattern and operates to inspect the next position as shown in 7080, 7040. Once the scanning pattern is complete, the method further includes generating output data 7090 that shows the sample response to illumination at the inspected position.

[0057] In addition, Figure 8 illustrates a method for inspecting a sample using the simultaneous operation of at least a first and a second X-ray source, according to some embodiments of the present disclosure. As illustrated in Figure 8, to initiate the inspection, a sample for inspection is typically provided within the inspection system. Generally, the sample is placed on a sample mount (110 in Figure 1), and the sample may be held on the sample mount by mechanical clamps and / or using low-pressure mounts. Once the sample is placed, the system may be operable by operating the sample mount to translate to a selected inspection spot. Typically, in some embodiments, the sample may undergo a selected translation shift to determine the sample size and position and to calibrate the alignment data. Once the sample mount has placed the sample at the selected inspection spot, the system operates to simultaneously illuminate the sample with at least a first and a second X-ray source and collect the fluorescence response from the sample. The collected fluorescence response is detected by one or more detectors and sent to a control unit for determining the response parameters for the inspected location.8060 According to the inspection pattern, the system can further operate the control unit to illuminate the same inspection location using a second X-ray source6070, collect the fluorescence response6080, and determine the response parameters6090.6080 After inspecting and determining the parameters for the selected inspection location, the control unit can repeat the inspection process6040 by operating the sample mount to move it parallel to the next inspection location6100, thereby illuminating the sample at a different selected location.6040 As described above, simultaneous illumination using at least the first and second X-ray sources allows for an increase in illumination intensity per unit area of ​​the illumination spot, and therefore allows for an increase in the signal-to-noise ratio in detecting small variations in the material composition of the sample. This can also be efficient for detecting low concentrations of selected elements in the sample.

[0058] As described herein, inspections using the first and second (and optionally additional) X-ray sources may be performed using a common scanning pattern, provided that the sample response at each position can be measured using different illumination characteristics. This reduces the registration processing required to align the inspection results.

[0059] Accordingly, as described above, this disclosure provides an inspection system and a method of operation that uses two or more X-ray sources for inspecting a sample. The two or more light sources are aligned in an angular orientation to provide illumination of a common illumination spot on the sample plane, and the sample plane is defined by the sample mount of the system.

[0060] It should be noted that the various features described in the various embodiments can be combined according to all possible technical combinations.

[0061] It should be understood that the present invention is not limited in its application to the details shown in the description or drawings contained herein. Other embodiments of the present invention are possible and can be carried out and implemented in various ways. Accordingly, it should be understood that the expressions and terms used herein are for illustrative purposes only and should not be considered limiting. Thus, those skilled in the art will understand that the concepts underlying this disclosure can be readily used as a basis for designing other structures, methods, and systems to accomplish some of the objectives of the subject matter of this disclosure.

[0062] Those skilled in the art will readily understand that, as described above, various modifications and changes can be applied to embodiments of the present invention without departing from the scope of the appended claims and the scope defined thereby.

Claims

1. X-ray inspection system, The system comprises at least two X-ray sources and at least one optical microscope, The at least two X-ray sources are positioned and oriented at a selected angle with respect to the inspection surface to provide a common illumination spot on the inspection surface. An X-ray inspection system in which at least one optical microscope is positioned between the at least two X-ray sources, aligned with respect to the normal to the inspection surface, and directed to provide an optical image of the common illumination spot on the inspection surface.

2. The inspection system according to claim 1, further comprising a sample mount for arranging a sample to be inspected, wherein the sample mount defines the inspection surface, and the at least two X-ray sources are positioned at a selected angle with respect to the inspection surface.

3. The inspection system according to claim 2, wherein the at least two X-ray sources are arranged at equal distances from the common illumination spot.

4. The inspection system according to claim 2, wherein the at least two X-ray sources are arranged symmetrically with respect to the normal to the inspection surface that intersects the inspection surface with the common illumination spot.

5. The inspection system according to claim 2, wherein the at least two X-ray sources are positioned at at least first and second different distances from the common illumination spot.

6. The inspection system according to claim 1, wherein the at least two X-ray sources are configured to emit X-ray radiation formed from one or more discrete energy bands.

7. The inspection system according to claim 1, wherein the at least two X-ray sources are multicolor X-ray sources.

8. The inspection system according to claim 1, wherein the at least one optical microscope is oriented to image the common illumination spot at an angle perpendicular to the inspection surface.

9. The inspection system according to claim 1, comprising two X-ray sources, wherein the two X-ray sources are positioned and oriented symmetrically on two opposing sides of a virtual plane perpendicular to the inspection surface.

10. The inspection system according to claim 1, comprising three X-ray sources perpendicular to the inspection surface and positioned and oriented in a triangular symmetry with respect to an axis intersecting the inspection surface in the common illumination spot.

11. The inspection system according to claim 1, wherein the at least two X-ray sources are positioned at two or more different angular orientations and distances, while being directed to illuminate the common illumination spot on the inspection surface.

12. The inspection system according to claim 1, further comprising a detector configuration comprising at least one X-ray detector configured to collect a fluorescence response from a sample in response to illumination using at least one of the at least two X-ray sources.

13. The inspection system according to claim 12, wherein the detector configuration comprises at least two detectors, each detector configured to collect X-ray fluorescence emission from the sample in response to irradiation by any one of the at least two X-ray sources.

14. The inspection system according to claim 12, wherein the detector configuration comprises at least one silicon drift detector.

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