Small-angle x-ray scatterometry

Abstract

To provide an x-ray apparatus, a method, and a non-transitory computer readable medium for extracting information about the array of high aspect ratio (HAR) holes in semiconductor wafers.SOLUTION: An x-ray apparatus is provided, comprising: a mount that is configured to hold a sample; an x-ray source 100 that is configured to direct an x-ray beam 130 toward a first side of a sample 190; an x-ray fluorescence (XRF) detector 750, positioned downstream to a second side of the sample, the detector being configured to detect, during a sample measurement period, at least a part of x-rays that have been transmitted through the sample; and an x-ray intensity detector (detector 702) that is positioned, during a beam intensity monitoring period, at a measurement position that is located between the x-ray source and the first side of the sample, so as to detect at least a part of the x-ray beam before the x-ray beam 130 reaches the sample 190.SELECTED DRAWING: Figure 30

Description

[Technical field]

[0001] The present invention relates generally to X-ray analysis, and more particularly to methods and systems for measuring the geometrical structure of semiconductor devices using X-ray scatterometry.

[0002] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of the following U.S. provisional patent applications: (a) U.S. Provisional Patent Application No. 62 / 694,097, filed July 5, 2018 (b) U.S. Provisional Patent Application No. 62 / 711,477, filed July 28, 2018 (c) U.S. Provisional Patent Application No. 62 / 711,478, filed July 28, 2018 (d) U.S. Provisional Patent Application No. 62 / 711,476, filed July 28, 2018 (e) U.S. Provisional Patent Application No. 62 / 757,297, filed November 8, 2018 [Background technology]

[0003] X-ray scatterometry techniques are used to measure the geometrical structure of semiconductor devices.

[0004] For example, U.S. Patent No. 7,481,579 describes an inspection method that includes directing a beam of X-rays to impinge on an area of ​​a sample having first and second features formed in first and second thin film layers, respectively, overlying a surface of the sample, and detecting and analyzing patterns of X-rays diffracted from the first and second features to assess the alignment of the first and second features.

[0005] U.S. Patent No. 9,606,073 describes an apparatus including a sample support that holds a sample in a plane having an axis, the plane defining a first region and a second region separated by a plane. A source mount in the first region rotates about the axis, and an X-ray source in the source mount directs first and second incident beams of X-rays to impinge on the sample at first and second angles along a beam axis orthogonal to the axis. A detector mount in the second region moves in a plane orthogonal to the axis, and an X-ray detector in the detector mount receives first and second diffracted beams of X-rays transmitted through the sample in response to the first and second incident beams, and outputs first and second signals, respectively, in response to the received first and second diffracted beams. A processor analyzes the first and second signals to determine a profile of the surface of the sample.

[0006] No. 9,269,468 describes an X-ray optical device including a crystal having a channel passing through it and having a number of inner surfaces. A mount is configured to hold the crystal in a fixed position relative to a source of an X-ray beam and to automatically shift the crystal between two predefined configurations: in the first configuration, the X-ray beam passes through the channel while diffracting from one or more inner surfaces, and in the second configuration, the X-ray beam passes through the channel without diffraction by the crystal.

[0007] U.S. Pat. No. 8,243,878 describes an analytical method that involves directing a focused beam of X-rays at a surface of a sample having an epitaxial layer formed thereon, and detecting X-rays diffracted from the sample while resolving the detected X-rays as a function of angle to produce a diffraction spectrum containing diffraction peaks and fringes due to the epitaxial layer.

[0008] (Directivity of high aspect ratio holes) High aspect ratio (HAR) holes are formed in semiconductor objects such as, but not limited to, semiconductor wafers. Aspect ratio (AR) is defined as the ratio of the transverse (out-of-plane of the wafer) dimension of the hole to the lateral (in-plane) dimension of the hole. High aspect ratios can exceed 10:1. The lateral dimensions can be on the sub-micron scale. HAR holes are either unfilled or filled with a material that may differ in composition from the surrounding material.

[0009] A stack of HAR holes (also called a sequence) may provide a structure with a higher aspect ratio than the AR of each HAR hole in the stack. If the HAR holes in a sequence are identical and perfectly aligned, then the AR of the sequence is the sum of the ARs of the HAR holes.

[0010] Due to imperfections in the manufacturing process, the HAR holes may be oriented away from the desired direction. The HAR holes may be misaligned with respect to each other.

[0011] Additionally or alternatively, at least one of the HAR holes may be oriented at an angle (relative to the surface of the wafer) that deviates from the desired deflection angle (e.g., the HAR hole should be perpendicular to the surface of the wafer, but the HAR hole may be at an angle to the surface of the wafer).

[0012] There is an increasing need to determine the orientation of HAR holes in a sequence of HAR holes belonging to one arrangement of sequences, each sequence containing a HAR hole.

[0013] (Extract information related to the arrangement of high aspect ratio holes) Small angle X-ray scattering (SAXS) can be used to measure the arrangement and shape of an array of HAR holes on or within a semiconductor sample. SAXS involves irradiating a semiconductor sample, wafer, or coupon with an X-ray beam. The X-ray beam passes through the semiconductor sample and is scattered by the array of objects. This provides a scattering pattern (also called a SAXS pattern or SAXS intensity distribution) that is detected by a detector.

[0014] The array of objects may include, in addition to the array of HAR holes, one or more additional repeating structures that include a scattering pattern generated by scattering of the X-ray beam by the array of HAR holes and by the one or more additional repeating structures.

[0015] There is an increasing need to provide systems, methods and computer program products for extracting information about the arrangement of HAR holes.

[0016] (Evaluate the object from different angles) Small angle X-ray scattering (SAXS) can be used to measure the arrangement and shape of an array of HAR holes on or within a semiconductor sample. SAXS involves irradiating a semiconductor sample, wafer, or coupon with an X-ray beam. The X-ray beam passes through the semiconductor sample and is scattered by the array of objects. This provides a scattering pattern (also called a SAXS pattern or SAXS intensity distribution) that is detected by a detector.

[0017] In some cases, it is necessary to measure a semiconductor object from different angles.

[0018] There is an increasing need to provide systems and methods for inspecting semiconductor objects from different angles to provide more accurate and refined shape information. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] U.S. Provisional Patent Application No. 62 / 694,097 [Patent Document 2] U.S. Provisional Patent Application No. 62 / 711,477 [Patent Document 3] U.S. Provisional Patent Application No. 62 / 711,478 [Patent Document 4] U.S. Provisional Patent Application No. 62 / 711,476 [Patent Document 5] U.S. Provisional Patent Application No. 62 / 757,297 [Patent Document 6] U.S. Patent No. 7,481,579 [Patent Document 7] U.S. Patent No. 9,606,073 [Patent Document 8] U.S. Patent No. 9,269,468 [Patent Document 9] U.S. Patent No. 8,243,878 Summary of the Invention

[0020] {Claims Summary will be inserted here in the final version.} [Brief description of the drawings]

[0021] The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken in conjunction with the following drawings: [Figure 1] FIG. 1 is a schematic diagram of a small angle X-ray scattering (SAXS) system, in accordance with an embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic diagram of a small angle X-ray scattering (SAXS) system, in accordance with an embodiment of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of a small angle X-ray scattering (SAXS) system, in accordance with an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram of a beam conditioning assembly, in accordance with one embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram of a slit assembly according to an embodiment of the present invention. [Figure 6]FIG. 2 is a schematic diagram of a slit assembly according to an embodiment of the present invention. [Figure 7A] 2 is a schematic diagram of a beam blocking assembly according to an embodiment of the present invention. [Figure 7B] 2 is a schematic diagram of a beam blocking assembly according to an embodiment of the present invention. [Figure 8A] 4 is a schematic diagram of an image showing the intensity of an X-ray beam detected by a detector in the absence of a beam blocker, according to another embodiment of the present invention. [Figure 8B] 4 is a schematic diagram of an image showing the intensity of an X-ray beam detected by a detector in the presence of a beam blocker, according to an embodiment of the present invention. FIG. [Figure 9A] 4 is a schematic diagram of an image showing the intensity of a scattered X-ray beam detected by a detector in the absence of a beam blocker according to another embodiment of the present invention. [Figure 9B] 3 is a schematic diagram of an image showing the intensity of a scattered X-ray beam detected by a detector in the presence of a beam blocker, according to an embodiment of the present invention. [Figure 10] FIG. 2 is a schematic diagram of a scanning scheme in which an X-ray detector including an array of sensors is moved in steps smaller than the distance between the sensors for improved angular resolution, according to an embodiment of the present invention. [Figure 11] FIG. 2 shows a portion of the detector and slit assembly. [Figure 12] FIG. 2 shows a portion of the detector and slit assembly. [Figure 13] FIG. 2 shows a portion of the detector and slit assembly. [Figure 14] FIG. 2 shows a portion of the detector and slit assembly. [Figure 15] FIG. 2 shows a portion of the detector and slit assembly. [Figure 16] FIG. 2 shows a portion of the detector and slit assembly. [Figure 17] FIG. 1 shows a system and a detector. [Figure 18] FIG. 1 shows a system and a detector. [Figure 19] FIG. 1 illustrates a portion of a system. [Figure 20] FIG. [Figure 21] FIG. 1 illustrates a sample, an X-ray beam, and a prior art XRF detector. [Figure 22] FIG. 1 illustrates an XRF detector. [Figure 23] FIG. 1 illustrates a sample, an X-ray beam and an XRF detector. [Figure 24] FIG. 1 shows a sample and a detector. [Diagram 25] FIG. 1 shows a sample and a detector. [Figure 26] FIG. 1 shows a system and a detector. [Figure 27] FIG. 1 shows a system and a detector. [Figure 28] FIG. 1 shows a system and a detector. [Figure 29] FIG. 1 shows a system and a detector. [Diagram 30] FIG. 1 shows a system and a detector. [Diagram 31] FIG. [Diagram 32] FIG. 1 shows an arrangement of aligned and unaligned stacks of HAR holes. [Diagram 33] FIG. 1 shows examples of aligned and unaligned stacks of HAR holes. [Diagram 34] FIG. 13 shows an example of a 1D small angle X-ray scattering (SAXS) pattern obtained when illuminating an array of stacks of HAR holes. [Diagram 35] FIG. 13 shows an example of the relationship between different range rotations and total intensity of the SAXS pattern of an array of aligned stacks of HAR holes. [Diagram 36] FIG. 13 shows an example of the relationship between different range rotations and total intensity of the SAXS pattern of an array of misaligned stacks of HAR holes. [Figure 37]FIG. 13 shows an example of the relationship between the rotation and total intensity of the first range of SAXS patterns of an array of unaligned stacks of HAR holes and an array of aligned stacks of HAR holes. [Figure 38] FIG. 1 illustrates an example of a method. [Figure 39] FIG. 1 illustrates an example of a method. [Diagram 40] FIG. 2 illustrates an example of a semiconductor object. [Diagram 41] FIG. 1 illustrates an example of a semiconductor object and some parts of an X-ray scatterometry apparatus. [Diagram 42] FIG. 1 illustrates an example of a semiconductor object and some parts of an X-ray scatterometry device. [Diagram 43] FIG. 1 illustrates an example of a method. [Diagram 44] FIG. 2 illustrates an example of a semiconductor object. [Diagram 45] FIG. 1 illustrates an example of a semiconductor object and some parts of an X-ray scatterometry device. [Figure 46] FIG. 1 illustrates an example of a semiconductor object and some parts of an X-ray scatterometry device. [Figure 47] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Figure 48] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Figure 49] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Figure 50] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Figure 51] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Figure 52] FIG. 1 shows an example of an X-ray beam cross section and a passing SAXS pattern. [Diagram 53] FIG. 1 shows an example of a 2D small angle X-ray scattering (SAXS) pattern obtained upon irradiation of an array of two-level HAR holes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (overview) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention described below provide improved methods and systems for analyzing geometric features formed in various types of semiconductor devices and test structures. X-ray scatterometry techniques for analyzing features, such as small angle X-ray scattering (SAXS), typically use X-rays with wavelengths on the order of 1 Angstrom. Such wavelengths are suitable for measuring high aspect ratio (HAR) features, such as HAR holes and trenches, fabricated in semiconductor wafers. Measurements of the geometric and other properties of the features are performed based on analysis of the intensities of X-rays scattered from the wafer at different angles.

[0023] In some embodiments, the SAXS system includes a motorized stage configured to move a planar sample, such as a wafer with a front and back surface facing each other, the front surface including various types of features, such as HAR features. Additionally or alternatively, the back surface of the wafer may be patterned with similar and / or other types of features.

[0024] In some embodiments, the SAXS system includes an X-ray source configured to direct a beam of X-rays toward the backside of the wafer. The SAXS system further includes at least one detector facing the front side of the wafer, the detector configured to detect at least a portion of the X-rays scattered from and / or transmitted through the wafer. The detector is configured to generate an electrical signal indicative of an intensity of the X-rays scattered from the HAR features on the front side of the wafer and received by the detector.

[0025] In some embodiments, the SAXS system comprises a processor configured to measure a property of the HAR feature of interest based on the electrical signal received from the detector.

[0026] In some embodiments, the SAXS system includes a beam conditioning assembly disposed between the X-ray source and the backside of the wafer and configured to condition a characteristic of the X-ray beam. The beam conditioning assembly includes a crystal including an entrance opening, an exit opening, and a V-shaped channel having opposing inner faces arranged such that the channel tapers from the entrance opening to the exit opening. The beam conditioning assembly further includes an X-ray mirror having a curved substrate with a multilayer coating. The mirror is configured to collect the beam and direct the collected beam at a first beam diameter to the entrance opening of the channel such that the beam emerging from the exit opening has a second beam diameter smaller than the first beam diameter.

[0027] In some embodiments, the SAXS system includes a first slit disposed between the x-ray source and the backside of the wafer to block the beam and adjust spatial characteristics of the blocked beam. The first slit includes first and second movable blades that are typically not parallel to one another. The edges of the first and second blades are disposed proximate to one another to define a slit. In some embodiments, the processor is configured to move the edges of the first and second blades to adjust the width of the slit and thereby control the spatial characteristics of the beam.

[0028] In an alternative embodiment, the SAXS system includes a second slit disposed between the X-ray source and the backside of the wafer. The second slit includes a movable blade with a plurality of scatter-free pinholes, each having a different width. The processor is configured to position selected scatter-free pinholes to block the beam by moving the movable blade to control spatial characteristics of the beam.

[0029] In some embodiments, the SAXS system directs a light beam at the backside of the wafer, detects optical radiation reflected therefrom using a detector, and outputs a signal indicative of the position of the wafer by the detector in response to the detected optical radiation. Based on the signal, the processor is configured to estimate position parameters such as the distance between the wafer and the detector and the orientation of the wafer relative to the detector. The SAXS system further comprises a motor controlled by the processor to align the orientation between the X-ray beam and the wafer in response to the signal.

[0030] In some embodiments, the wafer comprises a single crystal material and the detector is configured to measure one or more beams diffracted from lattice planes of the single crystal. The SAXS system further includes a controller configured to calibrate a position of the optical gauge relative to the lattice planes in response to the measured diffraction. Based on the diffracted x-rays, the controller is further configured to measure an orientation of the wafer relative to the detector and drive at least one motor to align an orientation between the wafer and the incident x-ray beam based on the measured orientation. In other embodiments, the processor can perform at least some of the above operations instead of the controller.

[0031] In some embodiments, the SAXS system includes a detector attached to one or more actuators configured to move the detector for scattered X-rays over a range of positions on the front surface of the wafer and measure the intensity of the transmitted X-rays as a function of scattering angle. This configuration allows the intensity of the transmitted X-rays to be measured with a higher angular resolution than the native resolution of the detector elements. In some embodiments, the processor is configured to control the actuators in response to electrical signals generated by the detectors, such that the acquisition time of the detectors is inversely proportional to the intensity of the detected X-rays.

[0032] In some embodiments, the detector includes a two-dimensional array (also referred to as a matrix) of sensor elements having a predefined pitch along height and width axes of the matrix, and the actuator is configured to step the detector through a range of positions with a resolution finer than the predefined pitch along both the height and width axes.

[0033] In some embodiments, the SAXS system includes a beam blocker having one or more beam stops. The beam blocker is comprised of a mount made of a material transparent to X-rays. The one or more beam stops are held within the mount and made of a material that is at least partially opaque to the X-ray beam. The beam blocker can be positioned such that the one or more beam stops block X-rays in a portion of an angular range, but X-rays at angles around the blocked portion of the beam pass through the mount to the detector. In one embodiment, at least one of the beam stops has an elliptical shape with smooth edges to prevent scattering of the beam from the beam stop.

[0034] The disclosed techniques improve the sensitivity of a SAXS system for detecting small geometric changes in a HAR feature by improving the angular resolution at which an x-ray beam scattered from the HAR feature is detected by a detector. Additionally, the disclosed techniques can be used to reduce the footprint of a SAXS system while maintaining high sensitivity and high resolution measurements.

[0035] (System Description) 1 is a schematic diagram of a small angle x-ray scattering (SAXS) system 10, in accordance with an embodiment of the present invention. In some embodiments, the SAXS system 10, also referred to herein as "system 10" for brevity, is configured to measure features on a sample, in this example a wafer 190, using scatterometry techniques, as described below.

[0036] In some embodiments, wafer 190 may include single crystal, polycrystalline, amorphous microstructures, or any suitable combination thereof, such as different microstructures or materials at different locations on wafer 190.

[0037] In some embodiments, system 10 includes an X-ray excitation source, referred to herein as source 100, powered by a high voltage power supply unit (PSU) 26. In some embodiments, source 100 is configured to emit an X-ray beam 130, also referred to herein for brevity as “incident beam 130” or “beam 130,” having an energy suitable to pass through wafer 190.

[0038] In some embodiments, the source 100 is configured to generate intense X-ray radiation having a wavelength of 0.1 nm or less with an effective spot size of about 150 μm or less.

[0039] In some embodiments, the source 100 may include any suitable type of high brightness x-ray source, such as, but not limited to, (a) a stationary solid anode, (b) a rotating solid anode, (c) a liquid metal, or (d) a synchrotron.

[0040] In some embodiments, the stationary solid anode-based source comprises a microfocus X-ray tube in which high energy electrons (>=50 keV) in a vacuum are incident on a molybdenum (Mo) or silver (Ag) or other suitable metal element or alloy anode. Such microfocus X-ray tubes are available from several suppliers, such as Incotec GmbH (Hamburg, Germany) and rtwRONTGEN-TECHNIKDR.WARRIKHOFF GmbH (Berlin, Germany).

[0041] In some embodiments, the rotating solid anode microfocus X-ray source may include a Mo or Ag anode or any other suitable metal element or alloy. Suitable rotating anode X-ray sources are available from several suppliers, such as Bruker AXS GmbH (Karlsruhe, Germany).

[0042] In some embodiments, the liquid metal x-ray source includes a molten anode. The anode may include any suitable element or alloys, such as an alloy of gallium (Ga) and indium (In). A suitable liquid metal x-ray source may be selected from, for example, one or more metal jet products offered by eXcillum AB (Kista, Sweden).

[0043] In some embodiments, synchrotron-based sources include compact electron accelerator-based X-ray sources, such as those provided by Lyncean Technologies (Fremont, CA 94539, USA) and those being developed by the scientific community.

[0044] In some embodiments, wafer 190 may include a semiconductor wafer having surfaces 191 and 192. In some embodiments, surface 191 includes high aspect ratio (HAR) features created on surface 191 and / or in the bulk of wafer 190 or materials deposited thereon using a suitable semiconductor process such as deposition, lithography, etching, etc. It is noted that in these embodiments, surface 192 typically remains flat and smooth and does not include HAR structures or other patterns created by lithography and etching. It is understood that during the creation of features on surface 191, some layers may be deposited as a blanket in some places on surface 192, for example using a chemical vapor deposition (CAV) process, which may cause some unintended topography on surface 192.

[0045] In other embodiments, at least a portion of surface 192 may be patterned with the HAR features described above and / or any other suitable type of features. In alternative embodiments, only surface 192 may include the HAR features described above.

[0046] In the context of this disclosure and in the claims, the term "aspect ratio" refers to the arithmetic ratio between depth and width (e.g., diameter in the case of a circular hole) or between height and width. Additionally, the term "high aspect ratio (HAR)" generally refers to an aspect ratio greater than 10. HAR structures, also referred to herein as HAR features, may include, for example, various types of three-dimensional (3D) structures formed on a logic device (e.g., a microprocessor), or a NAD flash memory device, or a dynamic random access memory (DRAM) device, or any other device.

[0047] In some embodiments, the HAR features may include one or more fin field effect transistors (FETs), gate-all-around (GAA) FETs, nanowire FETs in a complementary metal-oxide-semiconductor (CMOS) device, access transistors in a DRAM device, one or more channels in a 3D NAND flash device, one or more 3D capacitors in a DRAM device, or other types of HAR features.

[0048] In some embodiments, system 10 comprises a computer 20 including a processor 22, an interface 24, and a display (not shown). Processor 22 is configured to control the various components and assemblies of system 10, described below, and to process electrical signals received from a movable detector assembly, referred to herein as detector 240. Interface 24 is configured to exchange electrical signals between processor 22 and each of the components and assemblies of system 10.

[0049] Typically, the processor 22 comprises a general-purpose processor with appropriate front-end and interface circuitry that is programmed with software to carry out the functions described herein. The software may be downloaded to the processor in electronic form, for example over a network, or alternatively or additionally, may be provided and / or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory.

[0050] In some embodiments, beam 130 is emitted from source 100 and passes through a shutter and slit assembly of system 10, referred to herein as "assembly 110," made from any suitable material that is opaque to x-rays. In some embodiments, processor 22 is configured to set the position of assembly 110 using one or more controlled actuators, such as a motor or piezoelectric-based drive (not shown).

[0051] In some embodiments, assembly 110 is configured to improve user safety of system 10 by blocking x-ray radiation that is deflected from the designed optical path of beam 130. In some embodiments, processor 22 is configured to adjust the position and size of the slit to control the divergence and spatial shape of beam 130.

[0052] In some embodiments, the system 10 includes an additional slit controlled by the processor 22 to adjust the divergence, intensity, and spot size of the beam 130 and to block undesired scattered radiation.

[0053] In some embodiments, system 10 includes a beam conditioning assembly, referred to herein as "assembly 165," the structure of which is described in detail in FIG. 4 below. In some embodiments, assembly 165 includes optical elements such as mirror 120 and slit 125. Mirror 120 is configured to collect beam 130 from source 100 and assembly 110 and shape the optical properties of beam 130. For example, mirror 120 generates a collimated beam or a focused beam, or a combination thereof (e.g., collimated in the x direction and focused in the y direction). Slit 125 is configured to adjust properties of beam 130, such as the divergence angle and the spot size of the beam exiting mirror 120.

[0054] In some embodiments, the beam conditioning assembly 165 may include a vacuum chamber to prevent degradation of one or more of the aforementioned optical elements caused by interactions between air on the surfaces of the optical elements and ionizing radiation.

[0055] In some embodiments, the beam conditioning assembly 165 can have multiple configurations, some of which are described in detail in FIG. 4 below. For example, the processor 22 can instruct the beam conditioning assembly 165 to shape the first beam 130 as a collimated beam having a small spatial extent (i.e., spot size). The processor 22 can use this beam configuration to measure features located on test pads of small size, such as in logic applications where measurements are performed on test structures located in scribe lines between adjacent dies of the wafer 190.

[0056] In another example, the wafer 190 may include a memory device (e.g., DRAM, NADF flash) with a large array of repeating features (e.g., within a memory block) or a logic device with a memory section. In some embodiments, the processor 22 may apply a second beam 130 having a larger spot size and higher intensity compared to the first beam 130 to selected memory blocks of the die. The processor 22 may replace the mirror 122 to focus the beam 130 onto the active surface of the detector 240 to increase the resolution of the respective SAXS system (e.g., systems 10, 30, or 40 described above).

[0057] In some embodiments, system 10 includes a beam limiter, also referred to herein as a slit assembly 140, which includes one or more slits and / or movable blades, described in detail below in Figures 5 and 6. Slit assembly 140 is configured to control and / or refine the position and / or spot size and / or shape and / or convergence or divergence angle of incident beam 130 on surface 192 of wafer 190.

[0058] In some embodiments, system 10 includes a motorized rotation stage (not shown) having an axis of rotation about the y axis and centered on surface 191. In some embodiments, source 100, beam conditioning assembly 165, and one or more slit assemblies 110 and 140 are mounted on a rotation stage that is controlled by a motion controller and / or processor 22.

[0059] In some embodiments, the processor 22 can adjust or calibrate the angle between the incident beam 130 and the normal to the surface 192 of the wafer 190 to improve measurement conditions of the system 10.

[0060] In some embodiments, system 10 includes a chuck 200 on which wafer 190 is mounted. Chuck 200 is configured to mechanically support wafer 190 and allow beam 130 to be directed over a majority of the area (e.g., excluding at least a portion of the bevel of wafer 190 as shown in FIG. 1 ) or over the entire area of ​​surface 192.

[0061] In some embodiments, the chuck 200 may include a ring-shaped wafer support, although additionally or alternatively, the chuck 200 may include any other suitable design, such as a three-point kinematic mount.

[0062] In some embodiments, system 10 includes a motorized xyzχωφ stage, referred to herein as “stage 210,” to which a mount, e.g., chuck 200 is attached. Stage 210 is controlled by processor 22 in the xyz coordinate system of system 10, and is designed as an open frame (i.e., no material in the center) to allow incident beam 130 to directly impinge on surface 192 of wafer 190.

[0063] In some embodiments, stage 210 is configured to move wafer 190 in the x and y directions relative to beam 130 to set a desired spatial position of wafer 190 relative to incident beam 130. Stage 210 is further configured to move wafer 190 along the z axis to improve focusing of beam 130 at a desired location on surface 192, or any other suitable location on wafer 190. Stage 210 is further configured to apply rotations χ and / or ω parallel to surface 192 of wafer 190 about the x and y axes, respectively, and to apply an azimuthal rotation φ about the z axis perpendicular to surface 192 of wafer 190.

[0064] In some embodiments, the processor 22 is configured to select a predefined azimuthal angle φ to align the beam 130 with a selected feature in the structure to be measured. For example, the processor 22 can select a first azimuthal angle φ1 (not shown) to align the beam 130 with a line feature arranged in one dimension (1D) on the wafer 190. Additionally, the processor 22 can select a second azimuthal angle φ2 (not shown) to align the beam 130 with a pattern or array of holes or vias arranged in a two-dimensional (2D) pattern, such as a rectangular or hexagonal grid, on the wafer 190.

[0065] In an alternative embodiment, wafer 190 is mounted in a suitable fixture (instead of stage 210) to allow processor 22 to move source 100 and the aforementioned assemblies (e.g., slit assembly 110, and assemblies 165 and 140). The X-ray beam is directed to any desired location or locations of wafer 190. In other embodiments, system 10 includes another suitable set of mounts, such as a set of stages (e.g., a χωφ stage for wafer 190, and an xyz stage for the above assemblies), and processor 22 is configured to move surfaces 191 and 192 relative to beam 130 by controlling the set of stages.

[0066] In some embodiments, incident beam 130 impinges on surface 192, passes through wafer 190, and is scattered from the aforementioned HAR features formed on surface 191 of wafer 190. In an alternative configuration of wafer 190, surface 192 may include HAR features in addition to or instead of the patterned HAR features of surface 191, as described above. In this wafer configuration, incident beam 130 may be scattered from HAR features patterned on surface 192. In some embodiments, detector 240 of system 10 is configured to detect x-ray photons scattered from HAR features of both surfaces 191 and 192, as described in more detail below.

[0067] In some embodiments, the incident beam 130 may impinge on the surface 192 of the wafer 190 at point 111 perpendicularly or at any other suitable angle relative to the wafer 190. In one embodiment, a portion of the incident beam 130 is absorbed as it traverses the wafer 190, and the transmitted beam 220 exits the surface 191 of the wafer 190 in the same direction as the incident beam 130. The additional beam 122 scattered from the one or more HAR features described above exits at a different angle relative to the surface 191 of the wafer 22 than the transmitted beam 130.

[0068] In some embodiments, detector 240 is configured to detect x-ray photons of beam 222 impinging at one or more regions 226 on surface 224 of detector 240. Detector 240 may include one or more detectors of any suitable type, such as, but not limited to, a charge-coupled device (CCD), a CMOS camera provided by a number of suppliers, or an array detector made from silicon (Si) or cadmium telluride (CdTe) sensing layers, such as those manufactured by DECTRIS Ltd. (Baden, Switzerland), which supplies the 1D Mythen detectors and the 2D Pilatus and Eiger series of detectors.

[0069] In some embodiments, the detector 240 can be mounted on a precision motorized translation and / or rotation stage (not shown) configured to move and / or rotate the detector 240 based on a predetermined motion profile to improve its detection efficiency. An exemplary embodiment of the stage and motion control of the detector 240 is described in detail in FIG. 10 below.

[0070] In some embodiments, the detector described above is configured to detect the X-ray beam scattered from wafer 190, referred to herein as beam 222, and includes sufficiently small sensitive elements to provide the angular resolution required to measure the small-angle scattered intensity distribution from HAR features of wafer 190.

[0071] In some embodiments, system 10 includes one or more calibration gauges 215 that are used in calibrating and setting up system 10 to accurately measure properties of the aforementioned features patterned in wafer 190. At least one calibration gauge 215 is configured to generate electrical signals indicative of the height and tilt of a given location of wafer 190 relative to a predefined reference, as described in more detail below. The electrical signals are transmitted via interface 24 to processor 22 for analysis.

[0072] In some embodiments, system 10 can include two calibration gauges 215: a first calibration gauge 215 that faces surface 192, which is typically flat and does not have HAR features or other types of patterns, and a second calibration gauge 215 that faces surface 191, which is typically patterned and may also have HAR features as described above. In the example configuration of FIG. 1, the second calibration gauge is optional and is therefore shown as a dashed rectangle.

[0073] In other embodiments, system 10 has other suitable configurations of calibration gauges 215, for example, with only the second calibration gauge facing surface 191, or with the first and second calibration gauges 215 described above facing surfaces 192 and 191, respectively.

[0074] In some cases, calibration gauge 215 may respond differently to height and tilt on patterned surfaces (e.g., on surface 191) and flat surfaces (e.g., on unpatterned or blanket surface 192) of wafer 190 and therefore may require a pre-calibration step to improve the accuracy of height and tilt measurements.

[0075] In some embodiments, the processor 22 may receive signals indicative of the height and tilt of the patterned surface 191 from the aforementioned second calibration gauge 215. The pattern may affect (e.g., induce a deflection) the measurements performed by the second calibration gauge. In these embodiments, the processor 22 is configured to adjust or calibrate the angle between the incident beam 130 and the normal to the surface 192 of the wafer 190 to compensate for the pattern-induced deflection and thus improve the quality of the measurements performed by the system 10.

[0076] It should be noted that when calibration gauge 215 measures the height and slope of surface 192, or other unpatterned surfaces, there is typically no shift in the measurements.

[0077] In some embodiments, the calibration gauge 215, also referred to herein as an optical gauge, may include a light source and a sensor (not shown), or any other suitable configuration. The calibration gauge 215 is configured to measure the local height (e.g., distance along the z axis) and tilt (e.g., relative to the xy plane of an xyz coordinate system) of the surface 192 at selected coordinates of the x and y axes. In these embodiments, the light source and sensor are configured to operate at any suitable wavelength, e.g., visible, infrared (IR), or ultraviolet (UV), but typically not in the x-ray range.

[0078] In some embodiments, processor 22 is configured to calculate and display, on a display of system 10, a 3D map indicating the height and tilt of surfaces 191 and 192, or any other selected plane of wafer 10, relative to any suitable reference, such as the xy plane of an xyz coordinate system, based on the electrical signals received from calibration gauge 215. Processor 22 may calculate the 3D map based on measured locations on surface 192 and additional locations calculated between the measured locations, for example, by interpolating the height and tilt between two or more measured locations.

[0079] In some embodiments, the processor 22 is further configured to determine one or more starting positions for any X-ray based alignment procedures used by the system 10 to determine the zero angles (referred to herein as ω and χ) of the beam 130 for one or more target scattering structures.

[0080] In some embodiments, by independently measuring the directionality of (a) surfaces 191 and 192 of wafer 190 and (b) scattering features of interest (e.g., HAR structures) with respect to incident beam 130, processor 22 is configured to calculate the directionality of the scattering features with respect to surface 191 of wafer 190. This calculated directionality is particularly important for measuring HAR structures such as channel holes in 3D NAND flash memories.

[0081] In some embodiments, the wafer 190 is typically grown on a crystal that has a regular arrangement of the atoms that make up the crystal. The wafer 190 is then sliced ​​from the crystal so that the surface is aligned in one of several relative directions, referred to herein as the wafer orientation. This is also referred to as the growth plane of the crystalline silicon. The orientation is important to the electrical properties of the wafer 190. Different planes have different arrangements of atoms and lattices, which affect the way current flows in the circuits created in the wafer. Silicon wafer orientations are typically classified using Miller indices as (100), (111), (001) and (110).

[0082] In some embodiments, system 10 can include an integrated optical microscope 50, which can be used for navigation and pattern recognition, as well as a variety of other applications, such as optical inspection and / or metrology and / or probing patterns and other features on wafer 190.

[0083] In some embodiments, the optical microscope 50 is electrically connected to the computer 20 and configured to generate signals indicative of the pattern of interest so that the processor 22 can perform pattern recognition or any other of the aforementioned applications.

[0084] Additionally or alternatively, system 10 may include other suitable types of integrated sensors (not shown) configured to provide complementary metrology or inspection capabilities to system 10 .

[0085] In some embodiments, system 10 includes one or more X-ray diffraction (XRD) detectors, such as XRD detectors 54 and 56, which are configured to detect X-ray photons diffracted from a plane substantially perpendicular to surfaces 191 and 192 of wafer 190.

[0086] Reference is now made to inset 52, which is a top view of system 10. In some embodiments, XRD detectors 54 and 56 are positioned to generate a diffraction signal based on X-ray photons diffracted from several planes of the crystal lattice, which diffraction signal can be used for wafer alignment, as described below. The signal received from at least one of XRD detectors 54 and 56 can also be used for other applications.

[0087] The configuration of XRD detectors 54 and 56, optical microscope 50, and calibration gauge 215 (optionally) as shown in inset 52 is simplified for conceptual clarity and is provided as an example. In other embodiments, system 10 may include any other suitable configurations and arrangements of sensors, detectors, microscopes, and other suitable components and subsystems.

[0088] Returning now to the side view of FIG. 1 , in some embodiments, processor 22 may receive signals from XRD detectors 54 and 56 indicative of the intensity of Laue diffraction from planes substantially perpendicular to surfaces 191 and 192 of wafer 190. For example, crystal plane (555) is perpendicular to the surface of a silicon wafer having Miller indices (001), referred to herein as Si(001). Additionally or alternatively, processor 22 may receive signals from at least one of detectors 54, 56 and 240 indicative of the intensity of a first portion of beam 222 diffracted from any other lattice planes of wafer 190. These signals are also referred to herein as diffraction signals.

[0089] In some embodiments, processor 22 is configured to use X-rays diffracted from crystal planes substantially perpendicular to surface 191 and detected by XRD detectors 54 and 56 to determine the orientation of the incident beam and / or direct beam relative to the lattice planes of the single crystal wafer.

[0090] In another embodiment, detector 240 is further configured to detect diffracted X-ray photons from the Laue diffraction described above and generate a signal indicative of the intensity of the detected X-ray photons. {Although this is not the case in the present invention, this embodiment was added to the block engineering to prevent surrounding techniques that use a single detector to detect all diffracted and scattered X-ray photons.}

[0091] In some embodiments, the processor 22 receives a signal from the detector 240, also referred to herein as a scattered signal, indicative of the intensity of a portion of the beam 222 that has passed through the surface 192 and scattered from a HAR feature of the surface 191.

[0092] In an alternative embodiment, calibration gauge 215 may include one or more X-ray detectors positioned to measure Laue diffraction from a plane substantially perpendicular to surfaces 191 and 192 of wafer 190 and generate a signal indicative of the intensity of the measured Laue diffraction, referred to herein as an alternative diffraction signal.

[0093] In some embodiments, based on the one or more diffraction signals described above, processor 22 is configured to direct stage 210 to apply an ω and χ rotation to wafer 190. Processor 22 can use the position of wafer 190 corresponding to a maximum intensity of the diffracted x-rays detected by detector 240 to determine the tilt angle of beam 130 with respect to the crystal lattice in wafer 190.

[0094] In these embodiments, processor 22 is configured to establish the tilt angle between the crystal lattice planes and the surface of wafer 190 using measurements at two or more azimuthal angles that satisfy the diffraction condition. Additionally, processor 22 can apply X-ray diffraction (XRD) techniques to beam 130 to determine the orientation of surfaces 191 and 192 as a calibration technique for non-X-ray based gauges. For example, calibration can be performed by measuring a reference wafer, or any suitable reference structure mounted on a carrier wafer or tool, that has a known tilt angle between the crystal lattice and surfaces 191 and 192.

[0095] In these embodiments, detector 240 may include various suitable types of detection elements, such as, but not limited to, (a) 1D diode arrays made from silicon, germanium, or CdTe or other suitable materials, and (b) 2D X-ray direct or indirect detection cameras based on CCD, CMOS sensors, PIN diodes, or hybrid pixel detector technology.

[0096] In an alternative embodiment, system 10 may include an energy dispersive X-ray (EDX) detector assembly (not shown) in addition to calibration gauge 215. The EDX detector assembly includes a silicon-based or germanium-based solid-state EDX detector and a single-channel or multi-channel electronic analyzer. The EDX detector assembly is configured to measure the fluorescence of X-rays emitted, for example, from point 111 of wafer 190 or from a predetermined location of a standard wafer used to calibrate system 10, and generate an electrical signal indicative of the intensity of the fluorescent X-rays measured at point 111.

[0097] Based on the electrical signal, the processor 22 is configured to determine a first position of the point 111 and a deviation between the first position and a second position simultaneously acquired by the calibration gauge 215 .

[0098] In some embodiments, the X-ray source 100 and at least some of the X-ray optics between the source 100 and the wafer 190 are mounted on a first stage, and the wafer 190 is mounted on a second stage (e.g., stage 210). At least one of the optical microscope 50 and the optical gauge 215 is mounted on a third stage. By comparing the X-ray fluorescence (XRF)-based signal and the optical-based signal, the processor 22 is configured to identify, for example, a spatial offset between the optical pattern recognition camera of the optical microscope 50 and the X-ray beam 130, and to identify any misalignment between the aforementioned stages of the system 10.

[0099] In some embodiments, the processor 22 is configured to estimate motion errors in the stage 210, such as lead screw errors and non-orthogonality between the x and y axes of the stage 210, based on the received electrical signals. Furthermore, based on the fluorescent signals, the processor 22 is configured to calibrate the stage 210 by estimating the deviation between one or more points in the coordinate system of the system 10 and the actual position of each point on the stage 210, also referred to as stage mapping.

[0100] In some embodiments, system 10 includes a calibration scheme based on attenuation of an X-ray beam, referred to herein as a direct beam, passing through a suitable reference wafer (not shown), in addition to or instead of the energy dispersive X-ray (EDX) assembly described above. A suitable reference wafer may include patterned features adapted to attenuate the intensity of the direct beam by tens of percent, thereby allowing detector 240 to detect the photons of the direct beam without being affected (e.g., saturated). In an exemplary embodiment, the standard wafer may include various patterns of any suitable thickness, e.g., about 50 μm, of various suitable elements or alloys, such as, but not limited to, tungsten (W), tantalum (Ta), gold (Au) or silver (Ag).

[0101] In some embodiments, the processor 22 may use the calibration gauges 215 to align the beam 130 and the wafer 190 during measurements of structures on a product wafer, such as the wafer 190, or to calibrate the system 10, for example to prepare the system for use in production after performing maintenance operations.

[0102] In the alternative embodiment described above, the system 10 may include at least one calibration gauge 215 mounted on the opposite side of the wafer 190 to measure the tilt of the wafer 190 based on signals sensed from the surface 191. In one embodiment, the processor 22 is configured to calibrate the deviation between the tilt angles measured in blanket and patterned areas of the wafer.

[0103] In this embodiment, processor 22 positions calibration gauge 215 to direct a light beam to a first point, which is typically a blanket (i.e., no pattern), located adjacent an edge of surface 191, and measures the tilt of the wafer in the x and y axes. Processor 22 then positions calibration gauge 215 to direct a light beam to a second point on the pattern closest to the first point (e.g., 10 mm to 20 mm) and measures the tilt of the wafer in the x and y axes.

[0104] In some embodiments, based on the tilt measurements at the first and second points, processor 22 calculates an offset between the blanket surface and the patterned surface. Note that the wafer is typically rigid and the actual tilt angle does not change within a distance of 10 mm or 20 mm. The offset can be used as a calibration factor between the tilt measurements on the blanket and patterned surfaces of wafer 190 or any other type of measured wafer. In some embodiments, processor 22 can set the spot size of the light beam small enough to illuminate only the blanket surface near the wafer edge, but large enough to average the tilt measurements over various features of the pattern.

[0105] In some embodiments, wafer 190 comprises a single crystal material and at least one of X-ray diffraction (XRD) detectors 54 and 56 is configured to measure diffraction of beam 220 from lattice planes of the single crystal material. In some embodiments, in response to the measured diffraction, processor 22 is configured to calibrate an appropriate parameter (e.g., orientation) of calibration gauge 215 relative to the lattice planes.

[0106] 1 for illustrating calibration techniques performed by system 10 to improve measurements of features such as HAR structures on wafer 190. However, embodiments of the present invention are by no means limited to this particular type of exemplary configuration, and the principles of calibration gauge 215 described above may be implemented using any suitable configuration.

[0107] In one embodiment, the system 10 includes a beam blocking assembly, referred to herein as a beam blocker 230, made from a radiopaque or partially radiopaque material.

[0108] A beam blocker 230 is mounted in the system 10 between the wafer 190 and the detector 240 and is configured to block at least a portion of the beam 220 from illuminating the detector 240. In some cases, at least a portion of the incident beam 130 may be transmitted directly through the wafer 190.

[0109] In some embodiments, the beam blocker 230 may be positioned to partially block the directly transmitted incident beam over an angular range comparable to the spatial extent of the incident beam 130 .

[0110] An exemplary embodiment of a beam blocker is shown in detail in Figures 7A and 7B below.

[0111] In some embodiments, the opacity level and shape of the beam blocker 230 affects the signal generated by the detector 240, as shown in Figures 8A, 8B, 9A and 9B below.

[0112] In some embodiments, the detector assembly may include a single detector or an array of detectors arranged around the region 226. The beam detector may have a 2D configuration (i.e., an area detector) or a 1D configuration (i.e., a linear detector) and may count X-ray photons. The detector 240 may be flat or may have any suitable shape, such as an arc slanted towards the beams 222 and 220. In response to captured photons, 240 is configured to generate an electrical signal. One embodiment of the detector 240 is shown in detail in FIG. 10 below.

[0113] In some embodiments, system 10 includes a vacuum chamber 280 mounted between wafer 190 and detector 240 and configured to reduce unwanted air scattering of beam 220. In some embodiments, vacuum chamber 280 comprises a metal tube with x-ray transparent windows at each end, allowing beams 220 and 222 to pass between wafer 190 and detector 240.

[0114] In some embodiments, the system 10 includes a suitable vacuum pump, such as a roughing pump, controlled by the processor 22 to control the vacuum level in the vacuum chamber 280 and thereby improve the signal-to-background ratio (SBR) of X-ray photons impinging on the active surface of the detector 240.

[0115] In some embodiments, system 10 is configured to measure structural (e.g., dimensions and shape) and morphological parameters on the aforementioned features of wafer 190. For example, processor 22 is configured to measure a wide variety of parameters based on the electrical signals received from detector 240, including, but not limited to, height, depth, width and sidewall angle of patterned features, as well as film thickness and density anywhere across wafer 190.

[0116] In some embodiments, the processor 22 includes model-based software for analyzing the electrical signals received from the detector 240. The processor 22 uses a single structure model to simulate X-ray scattering for all angles of incidence with a common intensity normalization factor. The processor 22 then compares the correlation between the measured and simulated intensity distributions, for example, based on a numerical analysis of a goodness-of-fit (GOF) parameter.

[0117] In some embodiments, the processor 22 is configured to iteratively adjust the parameters of the model, for example by using an algorithm such as differential evolution (DE), to minimize the GOF parameters and obtain optimal model parameters.

[0118] In some embodiments, processor 22 may reduce correlation between model parameters by introducing values ​​measured by complementary techniques, for example the width of the top layer of a feature of interest measured by critical dimension scanning electron microscopy (CD-SEM), into the model parameters.

[0119] In some embodiments, system 10 may include one or more calibration targets having an array of periodic features that have been externally characterized using any suitable referencing technique other than small angle x-ray scattering (SAXS), such as an atomic force microscope (AFM). Processor 22 may use the calibration targets to calibrate the aforementioned assemblies of system 10 and as a reference for alignment between (a) beam 130 and wafer 190, and (b) beam 222 and detector 240.

[0120] In some embodiments, based on the above SAXS configuration and software algorithms, system 10 is configured to detect irregularity parameters in features of interest across wafer 190, such as horizontal and vertical roughness and pitch variations of sidewalls, such as pitch walking errors that may occur in a multi-patterning lithography process, or tilt and twist of channel holes due to etching processes in 3D NAND memory.

[0121] The configuration of system 10 is provided as an example to illustrate the particular problem addressed by embodiments of the present disclosure and to demonstrate the application of these embodiments in improving the performance of such systems, however, embodiments of the present invention are by no means limited to this particular type of exemplary system, and the principles described herein may be similarly applied to other types of x-ray systems used to measure features in any suitable type of electronic device.

[0122] 2 is a schematic diagram of a SAXS system 30 according to another embodiment of the invention. In some embodiments, the configuration of SAXS system 30, also referred to herein as "system 30" for brevity, is similar to the configuration of system 10, with wafer 190 tilted, also referred to herein as rotated, at any suitable angle (e.g., 45 degrees) relative to incident beam 130.

[0123] In some embodiments, the processor 22 is configured to instruct the stage 210 to tilt the wafer 190 about a tilt axis in the plane of the wafer 190, such as an azimuthal rotation ω about the y axis, and to orient at least one of the aforementioned slit assemblies parallel to the tilt axis.

[0124] In some embodiments, system 30 is configured to measure structures on wafer 190 having a low aspect ratio (e.g., a ratio of height to width less than 10). As described above, processor 22 is configured to rotate wafer 190 relative to incident beam 130, or alternatively, to rotate incident beam 130 relative to wafer 190. Processor 22 is configured to perform rotations about the y-axis, referred to herein as ω rotations, over a range of tens of degrees.

[0125] In some embodiments, the range of rotation angles may be symmetric, e.g., ±50 degrees relative to the surface of wafer 190, as shown above in Figure 1. In alternative embodiments, processor 22 may perform asymmetric rotations (e.g., -10 degrees to +60 degrees), e.g., by directing stage 210 to rotate wafer 190 to a desired angle within the range.

[0126] In some embodiments, the processor 22 is configured to measure the profile of a structure in multiple planes, for example by rotating the azimuthal angle of the wafer 190 relative to the beam 130. In the context of this disclosure and in the claims, the term "profile" refers to the shape of a single sidewall of a measured feature, or the change in width between two adjacent sidewalls along its depth or height, or the shift of the center of a hole as a function of depth. Further asymmetries of the hole, such as an elliptical rather than circular cross section, would typically require measurements at different azimuthal angles and chi-axes.

[0127] For example, processor 22 may measure the profile of a feature in a selected xy plane using a series of intensity measurements taken at different azimuthal angles. In some embodiments, processor 22 may perform this technique to measure the diameter of a channel hole in a 3D NAND memory device, or the width of a via and / or metal line in a local interconnect structure of a logic device.

[0128] In one embodiment, the beam blocker 230 is located proximate to the detector 240. In another embodiment, the beam blocker 230 may be located proximate to the wafer 190.

[0129] 3 is a schematic diagram of a SAXS system 40 according to another embodiment of the invention, also referred to herein as "system 40" for brevity in some embodiments. The configuration of SAXS system 40 is similar to that of system 10, except that beam blocker 230 is positioned closer to wafer 190.

[0130] In some embodiments, the processor 22 is configured to control the position of the beam blocker 230 at any suitable position along the path of the beam 220 so as to reduce the level of undesirable background and stray scatter detected by the detector 240.

[0131] In some embodiments, the processor 22 can set the position of the beam blocker 230 to one or more predefined mounting locations along the path of the beam 220. Additionally or alternatively, the processor 22 can adjust the position of the beam blocker 230 by controlling a motorized stage (not shown) configured to move and hold the beam blocker 230 at any suitable position between the wafer 190 and the detector 240.

[0132] The structure of the beam blocker 230 and associated assemblies, such as the stages described above, are described in detail below, for example, in Figure 7A. Further embodiments of the function and use of the beam blocker 230 in measuring features of interest on the wafer 190 are described in detail below, in Figures 8B and 9B.

[0133] The configurations of systems 10, 30, and 40 are provided as examples, however, embodiments of the present invention are by no means limited to this particular type of exemplary system and the principles described herein are similarly applicable to other types of metrology systems such as, but not limited to, reflection type x-ray metrology systems having both the x-ray source assembly and the detector assembly located on the same side of the wafer.

[0134] 4 is a schematic diagram of a beam conditioning assembly 165 according to one embodiment of the present invention. Beam conditioning assembly 165 may be used in any of systems 10, 30, and 40 described above, or in any other suitable configuration of a metrology system that applies an X-ray beam to measure features generated on wafer 190 or other types of wafers.

[0135] In some embodiments, beam conditioning assembly 165 comprises multiple sets of slit assemblies, referred to herein as assemblies 110, 300, and 320. Assembly 110 may be external to beam conditioning assembly 165, as shown in Figures 1-3, or may be incorporated therein, as shown in Figure 4. Similarly, assembly 320 may be part of or external to beam conditioning assembly 165.

[0136] As described in FIG. 1 above, the slit assembly of the beam conditioning assembly 165 is configured to block undesired scattered X-ray radiation that strays from the designed optical path of the beam 130 and / or to adjust the divergence, intensity and spot size of the beam 130.

[0137] In some embodiments, the beam conditioning assembly 165 includes a mirror 120 configured to shape the optical characteristics of the beam 130 after the beam passes through the slit assembly 110, as described in FIG. 1 above.

[0138] In some embodiments, the mirror 120 comprises a curved substrate 122 coated with a multilayer 124 of alternating thin (e.g., on the order of 1 micron) layers of heavy elements, such as tungsten (W), molybdenum (Mo) or nickel (Ni), and light elements, such as carbon or silicon. Such X-ray optics mirrors are provided by several sources, such as Incotec GmbH (Hamburg, Germany), AXO DRESDEN GmbH (Dresden, Germany) or Xenocs (Sassenage, France). In some embodiments, the configuration of the mirror 120 is adapted to provide a collimated beam in two directions (x, y). In other embodiments, the mirror 120 is configured to collimate the beam 130 in one direction (e.g., the x-direction) and to focus the beam 130 in an orthogonal direction (e.g., the y-direction).

[0139] In some embodiments, mirror 120 is configured to focus beam 130 onto surface 191 to obtain a minimum spot size. In other embodiments, focusing the X-ray beam at detector 240 can provide system 10 with improved angular resolution of the X-ray beam detected by detector 240, for example, in imaging HAR structures.

[0140] In the case of a 2D collimated beam, the beam conditioning assembly 165 may include two optics, such as two mirrors 120, facing each other to increase the solid angle (i.e., the two-dimensional angle) collected from the source 100 and to increase the X-ray flux of the beam 130.

[0141] In some embodiments, beam conditioning assembly 165 may include any suitable configuration of multiple multi-layer mirrors, such as mirror 120, attached to one or more motorized actuators controlled by processor 22. Processor 22 may adjust the configuration of each mirror 120 of beam conditioning assembly 165 to adjust the optical properties of beam 130 to obtain optimal measurement conditions.

[0142] In some embodiments, the beam conditioning assembly 165 comprises a crystal 310 made from a single crystal of germanium (Ge) or any other suitable material. The crystal 310 has a V-shaped channel 312 including an entrance opening 316, an exit opening 318, and opposing inner surfaces 314 and 315 arranged such that the channel portion 312 tapers from the entrance opening 316 to the exit opening 318.

[0143] In some embodiments, beam 130 passes through slit assembly 110 and into mirror 120, then through slit assembly 300 and entrance aperture 316. Beam 130 then strikes inner surface 314, then inner surface 316, and exits crystal 310 through exit aperture 318.

[0144] In some embodiments, the beam conditioning assembly 165 functions as a dispersive element and also functions as a beam compression optic configured to reduce the spot size of the beam 130 after exiting the slit assembly 320 of the beam conditioning assembly 165. The configuration of the beam conditioning assembly 165 enables beam compression and also reduces light flux loss compared to alternative techniques, such as the use of a crystal with parallel-sided channels, or one or more slits with one or more narrow apertures.

[0145] 4, slit assemblies 110, 300, and 320 are mounted before and after mirror 120 and crystal 310 to improve shaping of beam 130 along the optical path described above. In other embodiments, beam conditioning assembly 165 may include other suitable arrangements of slit assemblies interposed between source 100 and mirror 120, and / or between mirror 120 and crystal 310, and / or between crystal 310 and slit assembly 140, or any other element or assembly of any of systems 10, 30, and 40. For example, slit assembly 320 may be removed from assembly 165 or excluded from any of systems 10, 30, and 40.

[0146] 5 is a schematic diagram of a slit assembly 140 according to one embodiment of the present invention. As shown in FIGS. 1-3, the slit assembly 140, also referred to herein as a beam limiter, is positioned between the source 100 and the surface 192 of the wafer 190 so as to block the beam 130.

[0147] In some embodiments, the slit assembly 140 comprises two or more movable plates 520 positioned along a translation axis 522 at a predetermined distance from one another to define the slit 125. The distance between the plates 520 may be controllable, for example, by the processor 22. Alternatively, the distance between the plates 520 may be constant, for example, by not moving the plates 520 relative to one another or by selecting an appropriate type of slit 512 having stationary plates positioned at a desired distance from one another.

[0148] In some embodiments, the slit assembly 140 comprises two or more movable blades 510A and 510B having respective ends 514A and 514B that are not parallel to each other and are positioned adjacent to each other, thereby defining a microslit 515.

[0149] In some embodiments, the microslits 515 are configured to block a portion of the beam 130 impinging on the blades 510A and 510B without generating a scattered beam, and thus the blades 510A and 510B are also referred to herein as "anti-scatter blades." For example, the blades 510A and 510B are made from a single crystal material, such as tantalum (Ta), germanium (Ge), indium phosphide (InP), or a polycrystalline material, such as tungsten carbide, and have a thickness of about 1 mm or other suitable thickness.

[0150] In the context of this disclosure and in the claims, the terms "single crystal" and "monocrystalline" are used interchangeably and refer to a material having a structure formed from one crystal.

[0151] In some embodiments, the slit assembly 140 comprises actuators 500A and 500B configured to move the respective blades 510A and 510B along respective translational axes 516A and 516B to adjust the width of the microslit 515. The axes 16A and 16B are substantially orthogonal to the translational axis 22 in the xy plane.

[0152] In some embodiments, actuators 500A and 500B include one or more piezoelectric linear motors, such as the Piezo LEGS Linear 6G series offered by PiezoMotor (Uppsala, Sweden) or similar products from other vendors, such as Physik Instrumente (Karlsruhe, Germany). These motors may come with integrated high-resolution position sensors.

[0153] In some embodiments, the processor 22 is configured to position the slit assembly 140 in suitable proximity to the surface 192 of the wafer 190. The design of the micro-slit 515 allows the processor 22 to position the slit assembly 140 such that at least one of the edges 514A and 514B is located less than 10 mm from the surface 192. In other embodiments, the processor 22 can position the micro-slit 515 at any selected distance from the surface 192, for example between 100 mm and a few millimeters.

[0154] In some embodiments, the configuration of the micro-slits 515 allows the processor 22 to position the slit assembly 140 close to the surface 192 (e.g., up to a few millimeters) even when the wafer 190 is tilted, as shown in FIG. 2 above.

[0155] In some embodiments, the processor 22 is configured to set (a) the distance between the microslit 515 and the surface 192, (b) the distance between the edges 514A and 514B, and (c) the distance between the plates 520 so as to obtain desired optical properties of the beam 130 before the beam 130 impinges on the surface 192 and interacts with the structure and bulk of the wafer 190.

[0156] Reference is now made to inset 502, which is a plan view of the interruption between slit assembly 140 and beam 130. In the example of inset 502, processor 22 is configured to change the spatial shape of beam 130 from a circular shape of circle 524 to a rectangular shape shown by dashed rectangle 526 by (a) moving blades 510A and 510B along respective translational axes 516A and 516B, and (b) moving plate 520 along translational axis 522. Note that in this case, only the portion of beam 130 within the area of ​​dashed rectangle 526 impinges on surface 192, while the remaining portion of beam 130 located between the edge of circle 524 and dashed rectangle 526 is interrupted by slit assembly 140. As discussed above and shown in inset 502, at least one of translational axes 516A and 516B is orthogonal to translational axis 522.

[0157] The configuration of the slit assembly 140 is simplified for conceptual clarity and is provided as an example. In other embodiments, the slit assembly 140 can include more than two blades 510A and 510B and / or more than two plates 520. Additionally, the edges and / or edges 514A and 514B of the plates 520 may have any suitable shape, for example, both the plates 520 and edges 514A and 514B may have arcs that intrude into the area of ​​the respective plates 520 and blades 510A and 510B such that the beam 130 exiting the slit assembly 140 forms a circle rather than the rectangular shape discussed above.

[0158] In other embodiments, translational axes 516A and 516B may or may not be parallel to one another, and at least one of translational axes 516A and 516B may not be orthogonal to translational axis 522.

[0159] 6 is a schematic diagram of a slit assembly 150 according to another embodiment of the present invention. The slit assembly 150 can replace, for example, the slit assembly 140 shown in FIGS.

[0160] In some embodiments, the slit assembly 150 comprises a three-pinhole collimation system, also referred to herein as apertures 604 , 606 , and 608 , positioned along the translational axis 610 of the movable blade 550 .

[0161] In some embodiments, the slit assembly 150 includes an actuator 600 configured to move the blade 550 along a translation axis 610 .

[0162] Reference is now made to inset 602 , which is a plan view of the interruption between beam 130 and blade 550 .

[0163] In some embodiments, each aperture 604, 606, and 608 comprises a fixed dimension aperture, such as a SCATEX non-scattering pinhole manufactured by Incotec GmbH (Hamburg, Germany). In the example of blade 550, apertures 604, 606, and 608 have a circular shape and each aperture has a different diameter, for example, a diameter between about 20 μm and 500 μm.

[0164] In some embodiments, the blade 550, which acts as a frame for the scatter-free pinhole, is made from Ge for X-ray beams with low energy photons and from Ta for beams with higher energy photons.

[0165] In some embodiments, the configuration of apertures 604, 606, and 608 is adapted to reduce undesirable parasitic scattering that typically occurs when an X-ray beam passes through other types of apertures.

[0166] In some embodiments, actuator 600 may include any suitable type of motor coupled to a drive rod 620 configured to move blade 55 along a translation axis 610 .

[0167] In other embodiments, the configuration of actuator 600 may be similar to the configurations of actuators 500A and 500B described in the figures above.

[0168] In some embodiments, processor 22 is configured to determine the optical properties of beam 130 by instructing actuator 600 to position an aperture in a selected one of blades 550 to block beam 130. In the example of Figure 6, actuator 600 positions aperture 606 such that beam 130 passes through aperture 606 and a portion of beam 130 beyond the area within aperture 606 is blocked.

[0169] 7A is a schematic diagram of a beam blocker 230 according to one embodiment of the present invention. In some cases, at least a portion of incident beam 130 that strikes surface 192 is directly transmitted through wafer 190 and exits surface 191 without being scattered as part of beam 220. The directly transmitted portion of beam 220 is referred to herein as the "direct beam."

[0170] In some embodiments, the beam blocker 230 is typically placed in the center of the beam 220 to attenuate the X-ray radiation of the direct beam. This attenuation is necessary, for example, to prevent damage to the detector 240 and / or to prevent the detector from saturating and operating in a non-linear region. On the other hand, too much attenuation would preclude detection of fundamental signals that can be used by the processor 22 to track the angular position and intensity of the center of the beam 220. Thus, the attenuation of the beam blocker 230 is typically selected such that the intensity of the transmitted beam is attenuated to hundreds or thousands of photons per second at the detector 240.

[0171] In some embodiments, the beam blocker 230 comprises one or more beam blocking elements, such as a beam stopper 232, typically of an elliptical shape or any other suitable shape. In some embodiments, the beam stopper 232 is made from a material that is partially opaque to X-rays, also referred to as a high-Z material, typically comprising metallic elements such as tantalum or tungsten and / or any suitable metallic alloy.

[0172] As discussed above, the attenuation of beam stopper 232 is selected to allow reliable measurement of the angular position and intensity of beam 220 while preventing damage and non-linear distortions in the detection of detector 240 .

[0173] In some embodiments, the beam stopper 232 is further configured to minimize background intensity from the source, such as scattering from air or fluorescence, and other scattering from electronics behind the active area or surface of the detector 240. The active area of ​​the detector 240 may be partially illuminated with high energy x-rays having energies of 10 keV or greater due to limited thickness or low absorption of the detector material, e.g., 450 μm silicon.

[0174] In some embodiments, the beam stopper 232 has curved and / or smooth edges to reduce the scattered intensity of the direct beam.

[0175] In some embodiments, the beam blocker 230 includes a matrix 236, also referred to herein as a mount, which is made from a block of material adapted not to scatter x-rays, such as, but not limited to, diamond or a polymer such as a thin sheet of biaxially oriented polyethylene terephthalate (BoPET) polyester, also referred to herein as Mylar™, or poly(4,4′-oxydiphenylene-pyromellitimide) polyimide, also referred to herein as Kapton®.

[0176] In some embodiments, the beam stopper 232 is mounted in a recess (not shown) formed in the matrix 236 and is mechanically supported by the matrix material without the use of adhesives, which can scatter X-rays and therefore increase the level of background signal to the measurements. Because adhesives can degrade over time under X-ray irradiation, the absorbing mechanism can be fabricated using techniques used in electronics manufacturing, such as depositing a thin adhesive and seed layer with appropriate metallization and then electroplating a thicker X-ray absorbing material such as gold (Au), or by using additive printing techniques using inks incorporating a high concentration of metal nanoparticles followed by an annealing process.

[0177] In other embodiments, the beam stopper 232 can be coupled to the matrix 236 using other suitable techniques, such as an adhesive that does not scatter x-rays. It should be noted that the beam stopper 232 is adapted to attenuate the direct beam, such that the ambient scattered beam, shown in FIG. 1 as beam 222, is not attenuated because the support structure transmits the scattered x-rays of beam 222.

[0178] In some embodiments, the material of the beam stopper 232 partially transmits a direct beam of sufficient intensity so that the processor 22 can determine the intensity and position of the direct beam detected by the detector 240 without moving the beam stopper 232 away from the direct beam.

[0179] In some embodiments, beam blocker 230 comprises a mount, also referred to herein as precision motorized stage 233, which is controlled by processor 22 and configured to move along one or more axes. For example, X-axis and Y-axis translations in the configurations of systems 10 and 30 are shown above in Figures 1 and 2, respectively.

[0180] In some embodiments, matrix 236 is attached to stage 233 such that processor 22 sets the position of beam stop 232 relative to the direct beam transmitted through wafer 190. In other embodiments, stage 233 may include a rotation axis (not shown) to improve alignment of beam stop 232 with beam 220, and in particular with the direct beam. In another embodiment, stage 233 is also configured to move in the z-axis to enable the configuration of system 40 shown in FIG. 3 above, or to further improve the attenuation level of the direct beam.

[0181] In some cases, the attenuation of the direct beam may be sufficiently high by the wafer 190 or by any other element of the system 10. Thus, in other embodiments, the processor 22 is configured to move the beam stopper 230 away from the beam path 220. In these embodiments, since the beam stopper 232 is not blocking the beam 220, the processor 22 can monitor the intensity and position of the direct x-ray beam based on the direction and intensity of the direct beam detected by the detector 240.

[0182] The configuration of the beam blocker 230 is simplified for conceptual clarity and is provided as an example. In other embodiments, the beam blocker 230 may include any other suitable configuration and / or assembly for attenuating the intensity of the direct beam and / or managing detection of one or more beams 222 scattered from the wafer 190. For example, the beam blocker may comprise multiple beam stoppers 232 or may comprise two thin wires whose spacing can be adjusted to vary the effective width of the blocker.

[0183] 7B is a schematic diagram of a beam blocker 330 according to one embodiment of the present invention. The beam blocker can be substituted for, for example, beam blocker 230 of FIG. 1 above. In some embodiments, beam blocker 330 includes a matrix 333 made from synthetic diamond, or the material of matrix 236 described above, or any other suitable material adapted not to scatter the x-rays of beam 220.

[0184] In some embodiments, the beam blocker 330 includes multiple types of beam stoppers, each made from a suitable material. For example, gold-based beam stoppers having a thickness of about 50 μm, or other suitable thickness, or tungsten-based beam stoppers having a typical thickness between 50 μm and 100 μm, or any other suitable thickness, can be manufactured, for example, by laser cutting of a suitable tungsten foil.

[0185] In some embodiments, the beam stopper is bonded to the matrix 333 using any suitable technique, such as by recessing the matrix and placing the beam stopper in the recessed pattern, or any other suitable method, such as that described in Figure 7A above. For example, gold or tantalum can be deposited in the recessed pattern, or can be deposited on the surface of the matrix using chemical and / or physical techniques, and the laser cut tungsten pieces described above can be attached to the recessed pattern.

[0186] In some embodiments, the beam blocker 330 includes multiple geometric shapes and arrangements of beam stoppers. In the example of FIG. 7B, the beam blocker 330 includes five bar-shaped beam stoppers arranged in a row along the X-axis at a distance of 5 mm from each other and having a similar length of about 10 mm (measured along the Y-axis). The bar-shaped beam stoppers have different widths, for example between 0.1 mm and 0.5 mm. For example, the beam stoppers 332 and 334 have widths (measured along the X-axis) of about 0.5 mm and 0.3 mm, respectively, and the bar between the beam stoppers 332 and 334 has a width of about 0.4 mm.

[0187] In some embodiments, beam blocker 330 comprises five square beam blockers having the same arrangement along the X-axis (e.g., width and distance) of the bar beam blockers described above. For example, beam stoppers 336 and 338 have widths of 0.4 mm and 0.2 mm, respectively, and the square beam stopper disposed between them has a width of 0.3 mm.

[0188] In some embodiments, the beam blocker 330 may include beam stoppers of other shapes. For example, the T-shaped beam stoppers 335 and 339, and the L-shaped beam stopper 337 are all positioned in any suitable orientation and have any suitable width, length, and distance from each other. In the example of FIG. 7B, the T-shaped and L-shaped beam stoppers have a typical width of 0.2 mm, a length of 1 mm-2 mm, and a distance between adjacent beam stoppers of about 5 mm. Additionally or alternatively, the selected beam stoppers can be precisely positioned to use the T-shaped and L-shaped beam stoppers as alignment marks for blocking the beams described above.

[0189] The configuration of beam blocker 330 is provided as an example: in other embodiments, beam blocker 330 may include any other set of beam stops having any suitable shape and size, and arranged in any suitable layout.

[0190] Figure 8A is a schematic diagram of an image 402 showing the intensity of the beam 220 detected by the detector 240 in the absence of a beam blocker 230, according to another embodiment of the present invention. In the example of Figure 8A, an incident beam 130, which is collimated in both the x and y axes, impinges on a wafer 190 that includes an array of hexagonal features, such as HAR capacitors for a DRAM device.

[0191] In some embodiments, image 402 includes a spot 420 that indicates the intensity of the direct beam detected by detector 240. Image 402 further includes a plurality of spots 410 that indicate respective beams 222 scattered from the hexagonal array of DRAM devices. In some embodiments, the gray levels of spots 410 and 420 indicate the intensity (e.g., photon flux and its respective energy) of beam 220 detected by detector 240. In this example, white indicates high intensity and darker colors indicate lower intensity detected by detector 240.

[0192] In some embodiments, image 402 includes location 404 located between spot 410 and spot 420 within region 226 of detector 240, also shown in Figure 1 above. Image 402 further includes region 400 located outside region 226 of detector 240, referred to herein as background.

[0193] In some embodiments, the processor 22 is configured to set the characteristics of the beam 130 such that (a) the spots 410 have coherent scattering and therefore appear bright, (b) the locations 404 between the spots 410 have incoherent scattering and therefore appear darker than the spots 410 located within an imaginary circle 405 that surrounds the area in close proximity to the spot 420, and (c) the region 400 has no scattering or a scattering level below a predetermined threshold and therefore is displayed as black.

[0194] In some embodiments, without the beam blocker 230, the high intensity of the direct beam saturates the detector 240 in the area of ​​the spot 420, thus causing non-linear detection across the region 226. Thus, the spot 420 appears white, and the area within the circle 405 appears significantly brighter than the surrounding area of ​​the region 226.

[0195] As discussed above, due to coherent scattering, spot 410 appears brighter than locations 404 within the area of ​​circle 405. However, due to the increased incoherent background from detector 240, spot 410 appears darker than locations 404 at the periphery of area 226. Thus, due to the limited contrast caused by the increased background (incoherent x-ray intensity) from detector 240, the reliable detection area of ​​detector 240 is limited to the area within circle 405.

[0196] 8B is a schematic diagram of an image 406 showing the intensity of beam 220 detected by detector 240 in the presence of beam blocker 230, according to an embodiment of the present invention. Similar to the example of FIG. 8A, incident beam 130, which is collimated in both the x and y axes, impinges on a wafer 190 containing a hexagonal array of HAR capacitors of the aforementioned DRAM device.

[0197] In some embodiments, the image 406 includes a spot 430 that represents the intensity of the direct beam detected by the detector 240. The image 406 further includes a plurality of spots 440 that represent respective beams 222 scattered from the hexagonal array of DRAM devices.

[0198] In some embodiments, the beam blocker 230 attenuates the intensity of the direct beam detected by the detector 240 so that the spot 430 appears dark gray and the detector 240 does not introduce significant background intensity, as shown, for example, in FIG. 8A above.

[0199] In some embodiments, the detected intensity of the coherent scattering from the HAR features appears stronger within circle 40 compared to the periphery of region 226. Furthermore, the linear detection of detector 240 reduces the detected intensity from location 404 to the background level of region 400. Thus, within region 226, the contrast between all spots 440 and region 404 is high enough to perform measurements with high accuracy and precision. The term "accuracy" relates to measuring the actual dimensions of a feature of interest, whereas "precision" relates to the repeatability of multiple measurements performed on a given feature of interest.

[0200] In some embodiments, the presence of the beam blocker 230 allows the processor 22 to monitor the partially attenuated direct beam (e.g., during measurement of a HAR structure) in order to control parameters characteristic of the beams 130, 220, such as the incident flux of both beams 130 and 220 at their respective positions on the wafer 190 and the detector 240.

[0201] Figure 9A is a schematic diagram of an image 502 showing the intensity of beam 220 detected by detector 240 in the absence of beam blocker 230, according to another embodiment of the present invention. In the example of Figure 9A, incident beam 130, collimated in the x-axis and focused along the y-axis onto wafer 190 (e.g., onto surface 191), strikes wafer 190, which may contain 1D (lines) or an array of long, narrow 2D features, such as lines or grooves in devices, or dedicated metrology pads in scribe lines or elsewhere on the die.

[0202] In some embodiments, image 502 includes a spot 526 that indicates the intensity of the direct beam detected by detector 240. Image 502 further includes a number of features 510 that indicate respective beams 222 scattered from the array. In some embodiments, the grey level of features 510 and spots 526 indicates the intensity of beam 220 detected by detector 240. As described above in FIG. 8A, white indicates high intensity and darker colors indicate lower intensity detected by detector 240.

[0203] In some embodiments, the image 502 includes a location 504 located within the region 226 of the detector 240, between the feature 510 and the spot 526. The image 502 further includes a region 400 located outside the region 226 of the detector 240.

[0204] In some embodiments, the processor 22 is configured to set the properties of the beam 130 such that the feature 510 has coherent scattering, the location 504 has incoherent scattering, and the region 400 has no scattering.

[0205] In some embodiments, without beam blocker 230, the high intensity direct beam causes a sufficiently high background intensity and loss of contrast over region 226. Thus, spot 520 appears white, and the area within imaginary rectangle 505 appears substantially brighter than the surrounding area of ​​region 226.

[0206] As discussed above, due to coherent scattering, feature 510 appears brighter than location 504 within the area of ​​rectangular 505. However, the increased background from detector 240 results in a loss of contrast at the periphery of area 226. It should be noted that in the absence of beam blocker 230, the shape and dimensions of a reliable detection area of ​​detector 240 will depend on the type of feature being measured (e.g., its geometry) (e.g., round in FIG. 8A and rectilinear in FIG. 9A), the characteristics of beam 130, and other parameters of the system, such as the tilt angle of wafer 190 as shown in system 30 of FIG. 2 above.

[0207] 9B is a schematic diagram of an image 506 showing the intensity of the beam 220 detected by the detector 240 in the presence of a beam blocker 230, according to an embodiment of the present invention. In some embodiments, the processor 22 sets the incident beam 130 similar to the setting described above in FIG. 9A. Thus, the beam 130, collimated in the x-axis and focused in the y-axis, impinges on a wafer 190 containing the arrangement of lines or trenches described above.

[0208] In some embodiments, the image 506 includes a spot 530 indicative of the intensity of the direct beam detected by the detector 240. The image 506 further includes a number of features 540 indicative of each beam 222 scattered from the array of NAND flash memory devices.

[0209] In some embodiments, the beam blocker 230 attenuates the intensity of the direct beam detected by the detector 240 so that the spot 530 appears dark grey and the detector 240 is not saturated by excessive intensity.

[0210] In some embodiments, the detected intensity of coherent scattering from the lines or trenches appears stronger within the rectangle 505 compared to the periphery of the region 226. Nevertheless, the linear detection of the detector 240 reduces the detected intensity from the location 504 to background levels. Thus, within the region 226, the contrast between all the features 540 and the region 504 is high enough to perform measurements with high accuracy and precision.

[0211] As described above in FIG. 8B, the presence of the beam blocker 230 allows the processor 22 to monitor the partially attenuated direct beam in order to control parameters that characterize the beam 130 220.

[0212] 10 is a schematic diagram of a scanning scheme in which a detector 240 comprising an array of sensors 243 is moved in steps smaller than the spacing of the sensors to improve angular resolution, according to one embodiment of the present invention. In some embodiments, the detector 240 comprises an array of 1D or 2D sensor elements, referred to herein as sensors 243. In the example of FIG. 10, the detector 240 comprises 2D sensors 243 with predefined x-axis and y-axis pitches, referred to herein as Px and Py, respectively.

[0213] In the context of this disclosure and in the claims, the terms "Px" and "width axis" are used interchangeably, and the terms "Py" and "height axis" are also used interchangeably. In some embodiments, each sensor 243 is configured to generate an electrical signal indicative of the intensity of the direct beam and the beam 222 impinging on the active surface of the sensor. In some embodiments, the processor 22 is configured to generate an image, referred to herein as a pixel, based on the electrical signals received from each sensor 243. Thus, the dimensions of each pixel in the x and y axes are typically on the order of Px and Py, respectively.

[0214] In some embodiments, the detector 240 is mounted on a motorized stage 246 that includes translation and rotation motors (not shown). In some embodiments, the translation motors are configured to move the detector 240 in the x and y axes for scanning in the xy plane, and in the z axis for improving the focus of the beam 222 on the active surface of the sensor 243. In some embodiments, the rotation motor is configured to rotate the detector 240, for example about the z axis, to align the sensor 243 with the direction of scattered X-ray photons of the beam 222.

[0215] In some embodiments, stage 246 includes high precision encoders and / or interferometers (not shown) configured to measure the translational and rotational position of each axis of stage 246 at a predetermined frequency.

[0216] In some embodiments, system 10 may include a motion control assembly (not shown) controlled by processor 22. The motion control assembly may include a controller (not shown) configured to determine, for each motor, a respective motion profile (e.g., velocity, acceleration, and deceleration). The motion control assembly further includes one or more drivers, which are controlled by the aforementioned controller and configured to drive the motors of stage 246 to move according to the respective motion profiles and based on the current position measured by each axis' respective encoder or interferometer.

[0217] In other embodiments, the processor 22 is further configured to control the movement of the stage 246 and may be used for this purpose in addition to or instead of the controller.

[0218] In some embodiments, stage 246 is configured to move detector 240 along the x and y axes in selected respective step dimensions, referred to herein as Dx and Dy, and thus stage 246 is configured to move detector 240 in steps equal to a fraction of the pixel dimension discussed above.

[0219] Equations 1 and 2 below provide explicit expressions for estimating the dimensions Dx and Dy, respectively:

number

number

[0220] In some embodiments, the processor 22 is configured to receive the electrical signal generated by a given sensor 243 and set the rotation speed of the wafer 190 in response to the received signal. It should be noted that the acquisition time of the sensor 243 is inversely proportional to the intensity of the detected x-rays. For example, if the electrical signal received at a given area of ​​the wafer 190 indicates a relatively low intensity of the detected x-rays, the processor 22 can instruct the controller to slow down the motion of the detector 240 at that given area to increase the flux of photons, thereby increasing the signal-to-background ratio (SBR) detected at that given area.

[0221] Similarly, if relatively high intensity X-rays are detected at different rotation angles of the wafer 190, the processor 22 may instruct the controller to accelerate the movement of the detector 240 in different areas to increase measurement throughput.

[0222] In some embodiments, the processor 22 or a controller of the detector 240 is configured to control the acquisition time such that the detector 240 receives a predetermined range of intensities across the measurement locations on the wafer 190. The predetermined range of intensities allows for sufficient intensity to obtain a high SBR, yet prevents saturation and non-linear detection in each sensor of the detector 240.

[0223] In some embodiments, processor 22 is configured to acquire an image from a given sensor 243 at an acquisition time t based on the intensity of scattered photons of beam 222. Thus, for an array of nxm sub-pixels, processor 22 allocates a uniform time interval of t / (mxn) to each sub-pixel to acquire nxm sub-images within acquisition time t.

[0224] In some embodiments, the processor 22 is configured to move the detector 240 in a raster pattern along the x and y axes using step dimensions Dx and Dy, respectively, to measure the intensity distribution for each time interval at different positions of the detector 240 over the entire area of ​​a single pixel.

[0225] In some embodiments, the processor 22 is configured to combine the n x m sub-images received from each sensor 243 into a single pixel. The processor 22 may apply any suitable method, such as, but not limited to, simple arithmetic interpolation, or any suitable image processing algorithm, to the received sub-images to increase the resolution (e.g., angular resolution) of the composite image.

[0226] In some embodiments, processor 22 overcomes the resolution limits of the SAXS system caused by the available pixel dimensions of the respective detector assemblies by applying sub-pixel stepping and combining n.m sub-images to form a single image with improved angular resolution.

[0227] The following equation (3) provides a formula for calculating the angular resolution Δθ of a detector having pixel size p, positioned at a distance d from the target wafer:

number

[0228] Based on a typical pixel dimension of 172 μm, a distance of approximately 5 to 6 meters is required to obtain an angular resolution on the order of 0.3 mrad to 0.5 mrad.

[0229] In some embodiments, by using sub-pixel stepping as described above and combining n x m sub-images, the design distance between the detector 240 and the wafer 190 is reduced, for example by a factor of three, for example to less than 2 meters, while maintaining the required angular resolution.

[0230] In some embodiments, as described in more detail below, the processor 22 is configured to reduce the overall cycle time for measuring features of interest on the wafer 190 by increasing the speed of the detector 240 to a maximum level that enables acquisition of sub-images with a sufficiently high signal-to-background ratio (SBR).

[0231] The intensity of the scattered beam 222 typically depends on the Fourier transform of the electron density distribution ρ(r) of the scattering object. For weak scattering, the scattering amplitude “A” can be calculated using equation (4):

number

[0232] Equation (5) below provides a well-known expression for calculating the scattering intensity in the kinematic approximation:

number

[0233] The electron density ρe is related to the refractive index "n" of the scattering objects of the wafer 190. The following equation (6) provides an expression for calculating the refractive index n:

number

[0234] It should be noted that the value of the refractive index is close to 1 for all materials in the hard x-ray range, where the value of δ is of the order of 10-6.

[0235] Therefore, the electron density ρ can be calculated using the following equation (7):

number

[0236] In some embodiments, the processor 22 is configured to calculate a physical model including the topography and material of the feature of interest. The processor 22 is configured to compare the calculated and measured intensities using any suitable parameter, such as goodness of fit (GOF), and adjust the model parameters to minimize the difference between the calculated and measured data.

[0237] The dataset fitted by the processor 22 may include one or more 1D datasets, such as intensity distributions integrated along or across diffraction peaks for different orientations of the beam 130 and / or detector 240 relative to the wafer 190, or a series of 2D images of the scattered intensity patterns, or a combination thereof.

[0238] As described above, processor 22 is configured to reduce measurement time of features of interest by acquiring data using different acquisition times at different locations across wafer 190. In some embodiments, processor 22 may apply different acquisition times by detector 240 under various conditions, such as when measuring different types of features (e.g., geometric structures and / or materials), and / or layouts (e.g., single features or dense arrays of features), and / or angles between beam 130 and surface 192 of wafer 190, and / or angles between beam 222 and the active surface of detector 240.

[0239] In some embodiments, the processor 22 is configured to adjust the signal acquisition time such that the electrical signal received from the detector 240 has sufficient intensity to enable a sufficiently high SBR. The uncertainty of a measurement of the average intensity of scattered X-rays based on N counts is typically determined by Poisson counting statistics, with the standard error given by √N and the fractional error given by 1 / (√N). Thus, the processor 22 can reduce the measurement uncertainty by increasing the number of counts.

[0240] As described above, the processor 22 shortens the collection time in some locations where the intensity of the beam 222 detected by the detector 240 is high and increases the collection time in other locations where the intensity of the detected X-rays is low in order to obtain sufficient, but not excessive, X-ray photon counting statistics.

[0241] In alternative embodiments, the processor 22 may apply pre-processing, such as down-sampling and principal component analysis (PCA), to raw electrical signals received from the detector 240, such as 1D intensity profiles and / or 2D images for one or more rotation angles. The processor 22 may then apply one or more machine learning algorithms to the pre-processed data and the complemented data, which may be used to evaluate the value of data, such as electrical test data (e.g., of a feature of interest).

[0242] In these embodiments, processor 22 may use any suitable type of machine learning algorithm, such as the TensorFlow open source machine learning framework originally developed by Google (Mountain View, Calif.), as a training deck for deep learning using neural networks.

[0243] The processor 22 then applies the training model derived based on the previous data set to the data measured on the subsequent wafers 190 in order to predict the electrical performance of each device under test or to provide a user of the system 10, 30, 40 with useful attributes based on the measurement data of the subsequent wafers 190. It should be noted that using such machine learning algorithm embodiments may require high sampling to develop reliable regression-based models.

[0244] In some embodiments, detector 240 includes electronic circuitry (not shown) configured to distinguish between low and high energy photons of beam 220. In some embodiments, processor 22 is configured to reduce background intensities caused by, for example, x-ray fluorescence and high energy cosmic rays.

[0245] In other embodiments, processor 22 is configured to use software-based filters in combination with the sub-pixel resolution enhancements described above to filter out many of the high energy cosmic rays. In these embodiments, detector 240 may not include the hardware-based cosmic ray discrimination described above.

[0246] (Detection of the X-ray beam before it hits the sample) It has been found that the intensity of the direct beam passing through a semiconductor wafer in a SAXS system may not be an accurate measure of the intensity of the X-ray beam before it is incident on the semiconductor wafer. Accurate measurement of the incident beam intensity improves the quality of measurements of the microstructure (e.g., critical dimensions) of the semiconductor sample.

[0247] For example, if a high aspect ratio (HAR) hole in a semiconductor wafer is illuminated at zero (or small) tilt angle, there can be significant scattering from the HAR hole. HAR refers to the ratio of depth to width, and an aspect ratio greater than 10:1 is considered a high aspect ratio.

[0248] In such cases, an estimation of the direct beam intensity can be made by rotating the sample with a known tilt angle and correcting the intensity according to I(omega) = I0 * exp [-mu * t / cos(Omea)], where mu is the linear attenuation coefficient of the substrate (usually Si) at the incident X-ray energy and t is the thickness of the substrate. Sample rotation requires large, complex hardware and is time consuming.

[0249] Rotating the sample effectively reduces the intensity of the scattered X-rays more than the reduction in the direct beam due to attenuation, unless the scattering is negligibly small (e.g., <1%).

[0250] A system, computer program product, and method are provided for selectively placing a sensor (X-ray intensity detector) in the path of an X-ray beam to measure the intensity of the X-ray beam before the light beam reaches a semiconductor sample.

[0251] The sensor can be placed in the path of the X-ray beam during the beam intensity monitoring period and out of the path of the X-ray beam during the semiconductor sample measurement period. When the intensity of the SAXS pattern is relatively weak, it is necessary to remove the sensor from the X-ray path to avoid significantly reducing the intensity of the beam.

[0252] The sensor can be inserted into and removed from the path of the x-ray beam using any type of motion - such as but not limited to rotational motion, or a combination of linear and non-linear motion.

[0253] Linear motion can occur in any direction, and rotational motion can occur about any axis of rotation.

[0254] 11-14 show various non-limiting examples of rotation. In these figures, the sensor 702 can be held and moved by a mechanical mechanism (not shown in some figures). The mechanical mechanism can be an arm attached to an actuator. The sensor 702 can be held and / or moved by any other holding and / or moving mechanism.

[0255] The top of Figure 11 shows x axis motion 715, y axis motion 715, linear motion along an axis 713 oriented in both the x and y axes, and various rotations 711, 714, and 715. Note that the rotations are with respect to the support element that supports the sensor. Rotating the sensor itself about its center can only be used if such rotation would move the sensor out of the path of the x-ray beam.

[0256] FIG. 12 shows a sensor 702 outside the path of the x-ray beam (an "outside location").

[0257] FIG. 13 illustrates various rotations of a sensor 702 within the path X-ray beam (over an aperture or microslit formed by a plate 520 movable along blades 510A and 510B which are movable along respective translation axes 516A and 516B).

[0258] In the top part of FIG. 13, the sensor 702 is positioned over the opening and in a measurement position.

[0259] The center and bottom parts of FIG. 13 show the sensor 702 in an outer position and the path between the outer position and the measurement position (717 and 718 respectively).

[0260] In the center portion of FIG. 13, the sensor 702 rotates in a plane parallel to the plane of the plate 520, and in the lower portion of FIG.

[0261] The rotation can be in any plane having any spatial relationship to the plane of plate 520 .

[0262] The upper and middle parts of FIG. 13 are top views, and the lower part of FIG. 13 is a side view.

[0263] 14-16 show various spatial relationships between (a) sensor 702 and actuator 701, and (b) microslit assembly 140 including actuator 600 moving blade 550 which contains a series of fixed size apertures created using "scatterless pinhole" technology. These figures show various examples of movements that position sensor 702 in the path (measurement position) and out of the path (outer position) of the x-ray beam.

[0264] 15 and 16 also show the path of the X-ray beam when the sensor is removed from the path. When placed in the path of the X-ray beam (measurement location), the distance between the sensor 702 and the nearest beam shaping element can be, for example, millimeters (1 mm, a few millimeters, or less than 1 mm). Other distances can also be used. Similarly, a smaller rotation angle than that shown in FIG. 16 can be used to move the sensor 702 away from the beam shaping element by a millimeter distance to reduce the overall size of the setup.

[0265] 17-18 show the system 10 of FIG.

[0266] 17 and 18 provide examples of the relative positions of a sensor 702 in the path of the X-ray beam (FIG. 18) and outside the path of the X-beam (FIG. 17) - after the beam has been shaped.

[0267] FIG. 19 shows an example of a sensor 701 located after the beam conditioning assembly 165 of FIG.

[0268] The sensor 702 can be any type of sensor capable of measuring the intensity of the X-ray beam. For example, the sensor can be a silicon sensor, a gallium arsenide sensor, a CdTe sensor, a pin diode, etc. The sensor 702 can output an output current or other physical characteristic indicative of the intensity of the X-ray beam. According to yet another example, the sensor can be a metal foil that emits strong X-ray fluorescence, while the intensity of the fluorescent X-ray reflects the intensity of the X-ray beam.

[0269] FIG. 20 illustrates a method 905.

[0270] The method 905 includes: a step 915 of measuring the intensity of the X-ray beam with a sensor placed in the path of the X-ray beam and in front of the semiconductor sample. Step 915 occurs during a beam intensity period. Step 915 may include or be performed after the step of placing the sensor in the path of the X-ray beam. b. irradiating the semiconductor sample with the X-ray beam while the sensor is not in the path of the X-ray beam and detecting a signal (such as a SAXS pattern) from the semiconductor sample, step 925. Step 915 occurs during a measurement period of the semiconductor sample. Step 925 may include or be performed after a step of positioning the sensor outside the path of the X-ray beam. c. Processing 935 the signal sensed during step 935, eg, a measurement of the semiconductor sample, to provide an indication about the semiconductor sample.

[0271] Multiple iterations of steps 915, 925 and 935 may be performed.

[0272] Iterations of these steps may be performed several times during the measurement of a wafer, e.g. after each tilt of the sample. The intensities can then be used to normalize the measurement data or included in a parametric model to scale the intensities and correct for long-term drifts due to, e.g., temperature changes.

[0273] Blocking the direct beam has been found to improve the quality of the measurement of the scattered radiation. When measuring the intensity of the X-ray beam before it reaches the semiconductor sample, the direct beam can be attenuated and blocked or partially blocked by a static beam blocker. This simplifies the system because the beam blocker does not have to move between (a) a first position that blocks the direct beam and (b) a second position that does not block the direct beam or part of the SAXS pattern.

[0274] For example, if detectors with high absorption sensors such as thick CdTe or GaAs are used, then either instrument may not require a beam blocker.

[0275] With either instrument, the beam blocker can be removed to measure the beam intensity directly in a short measurement, and then inserted to measure scattering from structures, which takes more time - thereby protecting the detector from damage by avoiding long exposure to the most intense parts of the beam.

[0276] (Systems with XRF detectors) Semiconductor metrology tools including multiple X-ray based analytical techniques are generally known in the art, such as Vu et al. (US Pat. No. 6,381,303) combining XRF and XRR, and in particular SAXS+XRF combinations are known from Yokin et al. (US Pat. No. 7,551,719), Paris et al. (2007) or Beckman et al. (US Pat. No. US9,778,213). The apparatus can be used to measure multiple techniques, sequentially or simultaneously, using one or more X-ray beams and detectors. In previous SAXS+XRF tools, the detectors consisted of individual or arrays of X-ray detectors on the sides of the incident X-ray beam, as shown in FIG. 21 (X-rays 131 propagate along a specific axis perpendicular to the sample 190, while X-ray detector 744 is positioned on one side of the X-ray beam, relatively far from the sample and oriented at a specific angle).

[0277] Although this is convenient to implement using off-the-shelf components, the performance of such a system is reduced in terms of measurement accuracy at a given time, since the detector needs to be moved out of the path of the incident X-ray beam, which limits the possible solid angle of collection.

[0278] Within transmission geometry SAXS tools, X-ray fluorescence (XRF) detectors may be provided that address performance limitations due to limited solid angles of detector collection. The XRF detector may include one or more silicon drift detectors (SDDs) monolithically fabricated on a single module that includes an aperture that allows the beam to pass through.

[0279] FIG. 22 shows an XRF detector 750 that includes an aperture 7501 forming a single detection area 7502 and one or more SSDs.

[0280] FIG. 22 also shows an XRF detector 750' that includes an aperture 7501 and one or more SSDs that form multiple detection regions 7502A, 7502B, 7502C, and 7502D.

[0281] The number of separate detection regions, the shape and / or size of the separate regions may vary from that shown in Figure 22. The aperture allows the X-ray beam to pass through the XRF detector before striking the sample.

[0282] Because the detector is not positioned next to the incident X-ray beam, it can be placed very close to the sample surface (1–2 mm) and collect a much larger solid angle of the fluorescent X-rays emitted by the sample.

[0283] Quantification of emitted X-rays can be done by direct extraction, such as counting the number of X-ray photons within a specific energy region of interest (ROI), or from fitting to separate overlapping peaks.

[0284] Such a setup can be used in a combined transmission SAXS + XRF tool in two main ways, as disclosed below: 1) Placed close to the backside of the wafer (e.g., at a distance of less than 5 mm) and measuring fluorescent X-rays, such as SiKa radiation from a Si wafer, to monitor the intensity of the incident beam with greater precision than setups known in the prior art. 2) Placed near the front side of the wafer (e.g., at a distance less than 5 mm) to measure X-rays emitted from structures patterned on or in the substrate, such as logic or memory structures, including but not limited to FinFET and gate-all-around (GAA) transistors, DRAM, NAND, or emerging technologies such as phase change and magnetic memory. The XRF and SAXS signals can be measured sequentially or simultaneously, and the uXRF signal can be used in a variety of ways, including independent use to monitor the volume of material in structures containing W metal to quantify and monitor voids.

[0285] In either setup, the XRF detector is small enough that it can be rotated with the sample, if necessary, to maintain close proximity to the sample's surface. An illustrative example of such a detector is the Rococo series manufactured by PNDetector (Munich, Germany).

[0286] Since the X-ray beam of a transmission SAXS system has a relatively high energy, typically above 15 keV, only materials with relatively high atomic numbers, such as W, can be excited by this incident X-ray beam. Therefore, in another embodiment, it is envisioned that a second X-ray beam may be incident on the front surface of the sample with an energy different from that of the SAXS X-ray beam. The properties of this beam, including energy, size, and angular divergence, may be different from the SAXS beam and are individually optimized to excite fluorescence from elements that are not efficiently excited by the SAXS beam. Possible excitations include, but are not limited to, X-ray emission from common X-ray tubes such as Cu, Rh, and Mo.

[0287] 23 and 24 show an XRF detector 750 positioned upstream of the sample 190 to allow the X-rays 130 to pass through the XRF detector 750 and impinge on the sample 190. In FIG. 23, the X-rays are perpendicular to the sample 190 and the XRF detector 750. In FIG. 24, the X-rays are not perpendicular to the sample and the XRF detector 750.

[0288] The XRF detector is small and so close to the sample 190 that it may rotate with the sample.

[0289] The proximity of the XRF detector to the sample 190 and the aperture through which the X-rays can pass allows the XRF detector to collect the emitted fluorescent X-rays over a wide solid angle, which may be greater than 0.5 sr, approximately 1 sr, or greater than 1 sr.

[0290] 25 shows an example of a sample 190, an X-ray beam 130 and an XRF detector 750 (with an aperture 7501), and a second X-ray beam 132 illuminating (through aperture 7501) a second side of the sample 190. In this case, the XRF detector 750 can detect fluorescent X-rays emitted from the second side of the sample 190 or structures therein. The second X-ray beam 132 can be optimized to excite X-ray fluorescence of a particular element of interest.

[0291] 26 and 27 show a system 10 in which an XRF detector 750 is positioned upstream of the sample 190 at various sample tilt angles.

[0292] FIG. 28 shows system 10 with an XRF detector 750 positioned downstream of sample 190 such that second X-rays 132 pass through an aperture in the XRF detector 750 to irradiate the sample.

[0293] Figures 29 and 30 show a system 10 having a detector 702 (X-ray intensity detector) positioned upstream of the sample and an XRF detector 750 positioned downstream of the sample 190, with a second X-ray beam 130' irradiating the sample through an aperture. In Figure 29, the detector 702 is positioned in an outer position, and in Figure 30, the detector 702 is in a measurement position.

[0294] Sensing the entire X-ray beam can be more accurate than sampling a portion of the X-ray beam.

[0295] FIG. 31 illustrates a method 1200.

[0296] The method 1200 may include steps 1210, 1220, 1230, 1240, 1250, and 1260.

[0297] Step 1210 may include holding the sample with a mount.

[0298] Step 1220 may include directing an X-ray beam to a first side of the sample.

[0299] Step 1210 may include or may follow the step of positioning an XRF detector within less than 5 millimeters of the first side of the sample.

[0300] Step 1210 may include or may follow the step of positioning an XRF detector downstream on a second side of the sample.

[0301] Step 1230 may include detecting at least a portion of a small angle X-ray scattering (SAXS) pattern formed by the X-rays passing through the sample and exiting the second side with a SAXS detector positioned downstream from the second side of the sample.

[0302] Step 1210 may include or may be followed by disposing an XRF detector downstream of the second side, and step 1230 may include detecting at least a portion of the SAXS pattern that passes through an aperture of the XRF detector.

[0303] It should be noted that the XRF detector can be moved between a measurement position (where the XRF measurement is performed) and an outer position by a movement mechanism.

[0304] Step 1240 may include detecting fluorescent x-rays emitted from the sample with an x-ray fluorescence (XRF) detector.

[0305] Step 1250 may include responding to the detection. The response may include evaluating the sample, evaluating the x-ray beam characteristics, etc.

[0306] The method 1200 may also include placing an XRF upstream of the sample and determining an intensity of the X-ray beam based on the fluorescent X-rays detected by the XRF detector.

[0307] The XRF detector may include an aperture through which the X-ray beam may pass.

[0308] The XRF detector can be positioned upstream of the first side of the sample.

[0309] Step 1220 may include directing the x-rays through the opening.

[0310] Method 1200 may also include positioning an XRF detector downstream of the sample (e.g., facing a second side of the sample) and irradiating the sample with another X-ray beam (1260), which may pass through an aperture in the XRF detector. Step 1260 may be followed by step 1220.

[0311] The sample may be irradiated by the X-ray beam and the other X-ray beam simultaneously, at different times, or during partially overlapping periods of time.

[0312] XRF detectors can be shaped and positioned to detect the fluorescent x-rays emitted from a sample over a wide solid angle, which can be greater than 0.5 sr, about 1 sr, or even greater than 1 sr.

[0313] Step 1240 may include detecting fluorescent x-rays emitted from the sample by one or more radiation detecting elements of an XRF detector.

[0314] (Determining the direction of the HAR hole) A method may be provided for determining a directionality of a HAR hole within an array of a stack of HAR holes. The determining may include generating direction information indicative of a directionality of the HAR hole within the array of the stack of HAR holes.

[0315] The array includes stacks of substantially identical HAR holes, and it is assumed that a small angle X-ray scattering (SAXS) pattern obtained by irradiating the array indicates the orientation of the HAR holes in each stack.

[0316] The method can include determining an orientation of one or more HAR holes of a stack relative to a surface of the wafer. The method can include determining that the HAR holes of the stack are misaligned.

[0317] The bottom part of Figure 32 shows one arrangement of aligned stacks 800 of HAR holes. The top part of Figure 32 shows one arrangement of unaligned stacks 800 of HAR holes.

[0318] The left side of FIG. 33 shows an aligned stack 800 including a first HAR hole 801 and a second HAR hole 802.

[0319] A first HAR hole 801 is formed in a first layer 812 of the wafer.

[0320] A second HAR hole 802 is formed in a second layer 814 of the wafer.

[0321] The top surface of the first layer 812 is designated 811. The bottom surface of the second layer 814 is designated 818. The bottom surface of the first layer 812 and the top surface of the second layer are designated 813.

[0322] Both HAR holes are aligned with each other and perpendicular to the top surface 811 of the first layer 812 of the wafer.

[0323] The right side of Figure 33 shows a misaligned stack 800' that includes a first HAR hole 801 and a second HAR hole 802. Both holes are not perpendicular to the top surface 811 of the first layer 812 and are misaligned with each other (by a misalignment angle MA 823).

[0324] The first HAR hole 801 is tilted at a first angle OR182 with respect to the normal 819. The second HAR hole 802 is tilted at a second angle OR282 with respect to the normal 819.

[0325] The bottom part of FIG. 33 shows a misaligned stack 800″ including a first HAR hole 801 and a second HAR hole 802. Both HAR holes are not perpendicular to the top surface 811 of the first layer 812 and are also misaligned with each other. The first HAR hole 801 is tilted by a first angle OR1 821 relative to the normal 819. The second HAR hole 802 is tilted by a second angle OR2 822 relative to the normal 819. In this example, OR1 is different from OR2. The bottom part of FIG. 32 also shows a through path 818 that passes through both holes. The path 818 is tilted by OR3 824 from the normal 819.

[0326] Note that one HAR hole may be perpendicular to the first surface and another HAR hole may be oriented relative to the normal 819. In yet another example, one HAR hole of a stack may be spatially offset from another HAR hole of the stack - placing the center of one HAR hole away from the center of another HAR hole of the stack.

[0327] Note that each stack may contain more than two HAR holes.

[0328] 34 shows a SAXS pattern 1600 representing the intensity of radiation versus the collection angle of the sensor. The center of the SAXS pattern corresponds to a zero collection angle.

[0329] One or more pattern angular ranges are defined. The one or more angular ranges may be defined in any manner and / or by any entity.

[0330] The one or more angular ranges may be fixed, may vary over time, may be defined using machine learning, or may be otherwise defined. An angular range may be selected for providing directional information.

[0331] Different SAXS patterns are acquired for different angular relationships between the array and the illuminating X-ray. Different angular relationships can be obtained by rotating the array and / or by rotating the X-ray about the rotation axis.

[0332] Figure 53 shows an example of a 2D small angle X-ray scattering (SAXS) pattern obtained upon irradiation of an array of two-level HAR holes. It shows the interference pattern due to the in-plane spatial shift between the upper and lower levels of holes. The shift values ​​in the x and y directions are denoted as XJS and YJS, respectively.

[0333] The method may include calculating, for each of the different SAXS patterns, the total intensity within each of one or more angular ranges.

[0334] The method may also include calculating (ii) one or more total intensities (associated with different angular relationships) associated with one or more angular ranges of the different SAXS patterns and (ii) one or more relationships between different angular relationships between the illuminating X-rays and the sample (angle-total intensity relationships).

[0335] The relationship between one or more of these angles and the total intensity can be processed to provide directionality and n-plane shift information.

[0336] The intensity of X-ray scattering is proportional to the difference in electron density of the scattering structure relative to the surrounding environment, so the sum of the relationships has a first peak corresponding to the directionality of the first HAR hole and a second peak corresponding to the directionality of the second HAR hole.

[0337] There may be a third peak (not shown - between the first and second peaks) which represents the passage of the x-rays through a straight penetration path.

[0338] Note that in some cases different peaks may be merged (eg, if the peaks are not far enough apart from each other).

[0339] Processing the angle-total intensity relationship may include comparing the angle-total intensity relationship to one or more reference angle-total intensity relationships (of known stacks of HAR holes), may include applying neural networks / deep learning / machine learning to the angle-total intensity relationship to provide directional and / or spatial shift information, or may otherwise extract directional information from the angle-total intensity relationship. The processing step may include physical modeling using a limited subset of tilt angles that includes not only distinct peaks but also interference patterns at two arrays of coherently illuminated holes.

[0340] The angle-total intensity relationships of the different sequences can be compared to each other.

[0341] FIG. 35 shows (from top to bottom) the relationship between the three angles and the total intensity.

[0342] A first angle-total intensity relationship 1611 -obtained for the aligned stack and first angle range 1601.

[0343] A second angle-total intensity relationship 1612 -obtained for the aligned stack and second angle range 1602.

[0344] A third angle-total intensity relationship 1613 -obtained for the aligned stack and the third angle range 1603.

[0345] FIG. 36 shows (from top to bottom) the relationship between the three angles and the total intensity.

[0346] Fourth angle-total intensity relationship 1621 - for misaligned stacks (no straight line connection) and first angle range 1601.

[0347] Fifth angle-total intensity relationship 1622 - for misaligned stacks (no straight line connection) and second angle range 1602.

[0348] Sixth angle-total intensity relationship 1623 - for misaligned stacks (no straight line connection) and the third angle range 1603.

[0349] The fifth and sixth angle-total intensity relations contain two distinct peaks and therefore convey more directional information than the fourth angle-total intensity relation.

[0350] FIG. 37 shows the relationship between the two angles and the total intensity. A seventh angle-total intensity relationship 1631 -obtained for the aligned stack and first angle range 1601. Eighth angle-total intensity relationship 1632 - for misaligned stacks (not going straight through the path) and first angle range 1601.

[0351] The seventh and eighth angle-total intensity relationships have a single peak but are distinct from each other, which may provide clues as to whether the stacks are aligned or misaligned.

[0352] More detailed directional information can be obtained from the seventh and eighth angle-total intensity relationships by further processing, for example by comparing these angle-total intensity relationships to a reference angle-total intensity relationship of a known stack.

[0353] Directional information may be obtained from physical modeling using a limited subset of tilt angles that includes not only distinct peaks but also interference patterns at two arrays of coherently illuminated holes.

[0354] FIG. 38 illustrates a method 1700.

[0355] Method 18 may include steps 1710, 1720, 1730, and 1740. Step 1710 is followed by step 1720. Step 1720 is followed by step 1730. Step 1730 is followed by step 1740.

[0356] Different SAXS patterns are acquired for different angular relationships between the wafer and the irradiating x-rays in step 1710. Different angular relationships can be obtained by rotating the array and / or by rotating the x-rays about an axis of rotation.

[0357] In step 1720, for each of the different SAXS patterns, the total intensity within each of the one or more angular ranges is calculated.

[0358] In step 1730, one or more relationships (angle-to-total intensity relationships) are calculated between (i) one or more total intensities (associated with different angular relationships) associated with one or more angular ranges of different SAXS patterns and (ii) different angular relationships between the illuminating X-rays and the sample.

[0359] In step 1740, one or more angle-to-sum intensity relationships are processed to provide directional information.

[0360] Method 1700 may be performed by the apparatus that acquired the SAXS pattern, or may be calculated by a computer separate from the apparatus.

[0361] (Extract information related to the HAR hole sequence.) Apparatus, methods, and computer program products may be provided for extracting information regarding the sequence of HAR holes.

[0362] Apparatus, methods, and computer program products may be provided that can substantially remove from a SAXS pattern the contribution of scattering of the X-ray beam by other structures that are different from the array of HAR holes, thereby making the SAXS pattern more representative of scattering by the array of HAR holes (e.g., other structures that have a significantly different pitch than the HAR holes of the HAR array, structures that have a significantly different height than the HAR holes of the array, other structures may form non-repetitive structures, and may be one or more additional repeating structures). For ease of explanation, it is assumed that these other structures are one or more additional repeating structures. HAR holes are a non-limiting example of a HAR structure.

[0363] This method can be used to substantially remove other noise from the SAXS pattern, such as, but not limited to, scattering from detector electronics located behind the active area. At least a portion of the scattering pattern that reaches the active area passes through the active area, reaches the electronics, and may be backscattered (by the electronics) towards the active area.

[0364] Scattering from electronic circuits is only a non-limiting example of noise that can be removed from a SAXS pattern. Such scattering may be insignificant, and the methods, systems, and computer program products may be applied mutatis mutandis to other noises and / or may be applied even when such scattering is insignificant.

[0365] Apparatus, methods, and computer program products may be provided that can analyze complex structures (such as HAR holes) by treating other scattering elements of the semiconductor sample (such as one or more additional repeating structures) as sources of "background" radiation. In a simplified model, the intensity is assumed to be the incoherent sum of the intensity from the HAR hole and the intensity from one or more additional repeating structures (called underlayers): I_total(q)=I_HAR(q)+I_underlayers(q)+I_system(q)=I_HAR(q)+I_effectiveBacground(q).

[0366] Analysis of HAR holes may require a reliable model (which may not be possible due to the complexity of the underlayers or simply being unknown) or an estimate of I_underlayers(q) + I_system(q).

[0367] To estimate this "background" intensity distribution, one introduces a relative tilt between the X-ray beam and the semiconductor sample (e.g., by rotating the semiconductor sample around its omega axis) such that it is high enough, I_HAR(q)~0, which is typically somewhere in the range of 5-10 degrees (not an exact range, just an example).

[0368] These data are then used directly or fitted using nonlinear regression to create parametric models that include peak functions as found in X-ray analysis (Gaussian, Lorentzian, pseudo-Voigt, Pearson-VII sum, etc.). Using the empirical background directly can be advantageous when it cannot be adequately modeled using a generic peak function, for example the scattered intensity from the slits in the system.

[0369] Once the parameters of this “effective background” mode are determined, they are either kept constant or slightly varied and an intensity contribution is added to I_HAR(q) at low tilt angles to model the total scattered intensity distribution.

[0370] Taking into account the strength from the lower layers will give more accurate results in the HAR hole analysis.

[0371] FIG. 39 illustrates a method 1900.

[0372] The method 1900 may begin by step 1910 of introducing a first angular relationship between a semiconductor element and an x-ray beam.

[0373] Step 1910 may be followed by step 1920 of irradiating the semiconductor object with the X-ray beam while the first angular relationship is maintained and detecting a first SAXS pattern with a sensor.

[0374] While the first spatial relationship is maintained, the X-ray beam (before impinging on the semiconductor element) is aligned (or substantially aligned) with the HAR hole and is perpendicular (or substantially perpendicular) to the longitudinal axis of the one or more additional repeating structures.

[0375] While the first spatial relationship is maintained, the sensor detects a first SAXS pattern that has a backscattered radiation component (backscattered from the electronic circuitry) and also includes a scattering pattern that is strongly influenced by the array of HAR holes and one or more additional repeating structures.

[0376] Step 1920 may be followed by step 1930 of introducing a second angular relationship between the semiconductor element and the x-ray beam.

[0377] Step 1930 may be followed by step 1940 of irradiating the semiconductor object with the X-ray beam while the second angular relationship is maintained and detecting a second SAXS pattern with a sensor.

[0378] While the second spatial relationship is maintained, the X-ray beam (before impinging on the semiconductor element) is misaligned (or substantially misaligned) with the HAR hole and oblique (or substantially oblique) with respect to the longitudinal axis of the one or more additional repeating structures.

[0379] While the second angular relationship is maintained and the second spatial relationship is maintained, the sensor detects a second SAXS pattern that includes a scattering pattern that has a backscattered radiation component (backscattered from the electronic circuitry) and is still strongly influenced by the one or more additional repeating structures, but is less influenced by the array of HAR holes.

[0380] Step 1940 is followed by step 1950 of comparing the first and second SAXS patterns to generate information regarding the arrangement of the HAR holes.

[0381] In particular - step 1950 may include subtracting the first SAXS pattern from the second SAXS pattern to provide a SAXS pattern representative of the scattering of the X-ray beam by the array of HAR holes.

[0382] The alteration of the angular relationship can be performed by rotating at least one of the x-ray beam and the semiconductor object.

[0383] The maintenance of the first spatial relationship may relate to a first angular range between the X-ray beam and the semiconductor object. It has been found that when the aspect ratio of the HAR hole is greater than 10:1 (e.g., may be 40:1), the first angular range may be in the range of plus 2 degrees to minus 2 degrees from perfect alignment.

[0384] The maintenance of the second spatial relationship may involve a second angular range between the X-ray beam and the semiconductor object. It has been found that when the aspect ratio of the HAR hole is greater than 10:1 (e.g., may be 40:1), the second angular range may include a deviation of at least 2 or 3 degrees from perfect alignment.

[0385] Alternatively or additionally, the method may include converting the sample to a portion of the sample that does not contain HAR holes, such as a scribe line test pad, and acquiring an additional SAXS pattern that is less affected by the arrangement of HAR holes.

[0386] The second and / or additional SAXS patterns may be used to provide a SAXS pattern which may be a background SAXS pattern that can be used (together with the first SAXS pattern) to isolate the contribution of the array of HAR holes.

[0387] FIG. 40 shows an example of a sample such as a semiconductor object.

[0388] The semiconductor object includes an array of HAR holes 1882 and one or more additional repeating structures, such as transistors 1884(2) and interconnects 1884(1). The HAR holes 1882 may be disposed between multiple layers in a vertical NAND (or 3D NAND) memory array.

[0389] The aspect ratio of the structural elements that form the one or more additional repeating structures will be much smaller than the aspect ratio of the HAR hole. These structural elements may be much thinner (along the x-axis) than the HAR hole. Thus, the scattering due to the HAR hole is much more sensitive to rotation than the scattering due to the one or more additional repeating structures.

[0390] 41 illustrates an example of a semiconductor object and a portion of an X-ray scatterometry device, in which a first angular relationship is maintained between an X-ray 1852 and a semiconductor object 1880.

[0391] In FIG. 41 , the HAR holes 1882 and one or more additional repeating structures (collectively designated 1884) scatter X-rays to provide a scattering pattern 1854 produced by scattering of the X-ray beam by the array of HAR holes and by the one or more additional repeating structures.

[0392] The sensor 1820 has an active area 1822 and electronic circuitry 1824. The electronic circuitry backscatters radiation to provide backscattered radiation 1856.

[0393] The sensor 1820 detects a first SAXS pattern that has a backscattered radiation component (backscattered from the electronic circuitry) and also includes a scattering pattern generated by scattering of the X-ray beam by the array of HAR holes and by one or more additional repeating structures.

[0394] 42 illustrates an example of a semiconductor object and a portion of an X-ray scatterometry instrument, where a second angular relationship is maintained between the X-ray 1852 and the semiconductor object 1880.

[0395] In FIG. 42, the HAR holes 1882 have little effect on the second SAXS pattern, while one or more additional repeating structures (collectively designated 1884) scatter X-rays to provide a scattering pattern 1854 produced by scattering of the light beam by the one or more additional repeating structures.

[0396] The electronic circuitry 1824 backscatters the radiation and provides backscattered radiation 1856 .

[0397] The sensor 1820 detects a second SAXS pattern that has a backscattered radiation component (backscattered from the electronic circuitry) and also includes a scattering pattern produced by scattering of the X-ray beam by one or more additional repeating structures.

[0398] (Evaluate the object from different angles) An apparatus, method, and computer program product may be provided for inspecting a semiconductor object from different angles.

[0399] The semiconductor object includes an array of structural elements, the structural elements having an electron density substantially different from the electron density of their surroundings, the structural elements having a longitudinal axis in a particular direction, and exhibiting a high aspect ratio (HAR).

[0400] A non-limiting example of a structural element is a HAR hole (either a filled or unfilled HAR hole). Note that a structural element may be different from a HAR hole. For simplicity of explanation, it is assumed that the structural element is a HAR hole.

[0401] The strongest scattering (the most intense SAXS pattern) occurs when the X-rays are aligned with the structure because this is the direction that minimizes the net path and therefore the phase difference between the objects in the array, minimizing the drop in intensity due to destructive interference. This "forward" direction has the greatest number of visible diffraction peaks due to their high intensity, and it can be beneficial to have good angular resolution in two directions, along both the x and y axes.

[0402] Angular deviations from this setup (before hitting the semiconductor object) will provide poor quality SAXS patterns.

[0403] According to one embodiment of the present invention, a method may be provided for determining one or more X-ray beam parameters (such as the shape and / or size of the X-ray beam) as a function of an angular relationship between the X-ray beam and a semiconductor object.

[0404] For example, if an X-ray beam is aligned with the HAR hole (before hitting the semiconductor object) (assuming the sensor and semiconductor object are parallel to each other), the X-ray beam may be collimated in both the x- and y-axes. This would result in, for example, a circular cross-section of the X-ray beam at the plane of the sensor, the plane of the semiconductor object, and the output of the X-ray source - e.g., the plane of a microslit that shapes the cross-section of the beam.

[0405] The proposed system and method can change the angular range of illuminating the sample without changing the illumination area (on the sample). In a certain spatial relationship, there may be a low range of incidence angles (collimated beam) near the beam perpendicular to the feature / sample, while in another spatial relationship (e.g., larger tilt), the angular range may increase. In both cases, the spot (on the sample) can be kept in a relatively small area, for example by focusing the X-ray beam to a spot. The slit (opening), in front of the optics and in front of the sample towards the source, can be widened to increase the angular range. Furthermore, the proposed system and method can change the area of ​​illumination without changing the angular range of illuminating the sample by changing the size of the opening of the slit in front of the optics and in front of the sample.

[0406] If we assume that the semiconductor object is rotating with respect to the detector and the X-ray beam, then at the plane of the sensor and output of the X-ray source, the X-ray beam will be collimated along the x axis, but not collimated along the y axis - and may have an elliptical shape. In the plane of the semiconductor object, the X-ray beam is circular.

[0407] The eccentricity of an ellipse changes with angular misalignment.

[0408] A wider range of incidence angles may increase the intensity of the SAXS pattern, but may also increase overlap between the diffraction orders in the SAXS pattern. The overlap as the tilt angle increases is tolerated and may be beneficial - it may be compensated for by using SAXS patterns obtained with less overlap or no overlap, obtained at lower angular misalignments.

[0409] Since there are fewer diffraction peaks and the intensity is relatively low compared to the smaller sample tilt angles, the increased intensity may be more beneficial than the reduced angular resolution at larger tilt angles.

[0410] Varying the angular illumination range at the sample can be performed in various ways - for example, by using apertures of adjustable shape and / or size, by selecting between apertures of different shapes and / or sizes, by using various reflective and / or diffractive optics optimized for collimated and focused beams, etc.

[0411] The parameters of the X-ray beam (e.g., the size and / or eccentricity of the elliptical cross-section of the X-ray beam) may be set based on at least one of the following:

[0412] The deflection angle between the X-ray beam and the specific direction in which the HAR holes and the X-ray beam are aligned. For example, the size of the beam decreases as the angle of the sample increases in order to maintain a constant illumination area on the sample - this can be important for small test pad structures. Also, if the X-ray beam is substantially parallel to the axis of the HAR holes, the divergence of the X-ray beam can be reduced (increasing the resolution) in order to clearly resolve the individual diffraction orders and increase the sensitivity to disorder in the array - which is not accessible at the higher divergences used to evaluate the average shape of the HAR holes. As an example, for HAR holes with an in-plane spacing of about 150 nm, a typical high-resolution divergence is about 0.2 mrad, whereas the high-flux divergence used to evaluate the average shape is about 0.4-0.5 mrad.

[0413] Measured and / or estimated parameters of the detected SAXS pattern (such as, but not limited to, the measured and / or estimated SNR of the SAXS pattern), for example: When measuring 2D structures that do not require high resolution in both directions in the plane of the sample to determine the shape of the structure, such as HAR trenches, the divergence angle of the X-ray beam can be adjusted in one direction to significantly increase the incident flux and improve accuracy / precision or throughput.

[0414] The expected overlap between different lobes of a SAXS pattern depends on the pitch of the structure relative to the divergence of the incident X-ray beam. Smaller pitch structures have a larger spacing between adjacent diffraction orders and therefore benefit from a higher flux of highly dispersed beams than larger pitch structures. For example, scattering from dynamic random access memory (DRAM) capacitor structures with pitches less than 100 nm can be advantageously measured with beams with large divergences (e.g., greater than 0.5 mrad) compared to 3D NAND channel holes with pitches of about 150 nm and divergences greater than 0.5. Dispersions greater than 0.5 mrad will cause significant overlap between adjacent diffraction orders, reducing the accuracy and precision of profiles from subsequent structures.

[0415] Information already obtained from previous measurements - especially if one or more different angular relationships existed between the X-ray beam and the semiconductor object during the previous measurements.

[0416] The importance and / or priority of structures in the semiconductor object, or the relevance of information that may exist in the overlapping regions between the lobes of the SAXS pattern. For example, in the case of a vertical stack of two arrays of HAR holes, information about the in-plane offset between the arrays can be determined using beams with greater divergence, higher flux and higher throughput than would be possible if precisely shaped holes were required, since the interference pattern is rather infrequent compared to the spacing between adjacent diffraction orders. (See Figure 53)

[0417] It should be noted that the shape of the x-ray beam may be elliptical or non-elliptical, or may be polygonal, curved, or the like.

[0418] Note that the energy density of the X-ray beam may vary from measurement to measurement.

[0419] FIG. 43 illustrates the method 1000.

[0420] Method 1000 may begin by step 1010 of receiving or determining parameters of the X-ray beam (such as at least one of intensity, divergence, shape, and size) and determining an angular relationship between the semiconductor element and the X-ray beam.

[0421] Step 1010 may be followed by step 1020 of introducing an angular relationship between the semiconductor element and the X-ray beam.

[0422] Step 1020 may be followed by step 1030 of irradiating the semiconductor object with an X-ray beam having the parameters while the angular relationship is maintained and detecting a SAXS pattern (or any other signal) with a sensor.

[0423] Step 1030 may be followed by step 1010, during which the method may vary at least one of: (a) one or more parameters of the x-ray beam; and (b) an angular relationship.

[0424] Multiple iterations of steps 1010-1030 may be performed.

[0425] The determination of step 1010 may be responsive to the results of step 1030. For example, the SAXS pattern (or any other signal) may be processed and / or analyzed to determine one or more parameters of the SAXS pattern (or any other signal).

[0426] Step 1010 may include determining parameters of the x-ray beam (e.g., size and / or eccentricity of the elliptical cross-section) based on at least one of the following: A. Declination angle. b. Measured and / or estimated parameters of the detected SAXS pattern (such as, but not limited to, the measured and / or estimated SNR of the SAXS pattern). c. Expected overlap between different lobes of the SAXS pattern. d. Information already obtained from previous measurements - when one or more different angular relationships existed between the X-ray beam and the semiconductor object. e. The importance and / or priority of the structure of the semiconductor object. f. The relevance of information that may be present in the overlapping regions between the lobes of the SAXS pattern.

[0427] (for example-) The deflection angle between the X-ray beam and the particular direction in which the HAR holes are aligned. For example, to maintain a constant illumination area on the sample, the size of the beam can be reduced as the angle of the sample increases, which can be important for small test pad structures. Also, if the X-ray beam is substantially parallel to the axis of the HAR holes, the divergence of the X-ray beam can be reduced (increased resolution) to clearly separate individual diffraction orders and increase sensitivity to disorder in the array that is not accessible with the higher divergences used to evaluate the average shape of the HAR holes. As an example, for HAR holes with an in-plane spacing of about 150 nm, a typical high-resolution divergence is about 0.2 mrad, whereas the high-flux divergence used to evaluate the average shape is about 0.4-0.5 mrad.

[0428] Measured and / or estimated parameters of the detected SAXS pattern, such as but not limited to, the measured and / or estimated SNR of the SAXS pattern. For example, the divergence angle of the X-ray beam can be adjusted in one direction to significantly increase the incident flux and improve accuracy / precision or throughput when measuring 2D structures that do not require high resolution in both directions in the plane of the sample to determine the shape of the structure, such as HAR trenches.

[0429] The expected overlap between different lobes of a SAXS pattern depends on the pitch of the structure relative to the divergence of the incident X-ray beam. Smaller pitch structures have a larger spacing between adjacent diffraction orders and therefore benefit from a higher flux of highly dispersed beams than larger pitch structures. For example, scattering from dynamic random access memory (DRAM) capacitor structures with pitches less than 100 nm can be advantageously measured with beams with large divergences (e.g., greater than 0.5 mrad) compared to 3D NAND channel holes with pitches of about 150 nm and divergences greater than 0.5. Dispersions greater than 0.5 mrad will cause significant overlap between adjacent diffraction orders, reducing the accuracy and precision of profiles from subsequent structures.

[0430] Information already obtained from previous measurements - especially if one or more different angular relationships existed between the X-ray beam and the semiconductor object during the previous measurements.

[0431] The importance and / or priority of structures in the semiconductor object, or the relevance of information that may exist in the overlapping regions between the lobes of the SAXS pattern. For example, in the case of a vertical stack of two arrays of HAR holes, information about the in-plane offset between the arrays can be determined using beams with greater divergence, higher flux and higher throughput than would be possible if precisely shaped holes were required, since the interference pattern is rather infrequent compared to the spacing between adjacent diffraction orders. (See Figure 53)

[0432] It should be noted that during one or more iterations of steps 1010-1030, the semiconductor object may be illuminated with X-rays propagating in a particular direction.

[0433] FIG. 44 shows an example of a semiconductor object.

[0434] The semiconductor object includes an array of HAR holes 1882. The HAR holes 1882 may be disposed between multiple layers in a vertical NAND (or 3D NAND) memory array or test structure.

[0435] 45 illustrates an example of a semiconductor object and a portion of an X-ray scatterometry instrument, in which a first angular relationship is maintained between an X-ray 1852 and a semiconductor object 1880.

[0436] In FIG. 45, HAR holes 1882 scatter X-rays to provide a scattering pattern 854 that is produced by scattering of the X-ray beam by the array of HAR holes.

[0437] 46 illustrates an example of a semiconductor object and a portion of an X-ray scatterometry instrument, where a second angular relationship is maintained between the X-ray 1852 and the semiconductor object 1880.

[0438] 47-52 show cross sections of the X-ray beam at (a) the plane 140' of the microslit 140, (b) the plane 190' of the semiconductor object 190, and (c) the plane 124' of the sensor 140. FIG.

[0439] Figures 47-50 show four examples of four angular relationships - starting with alignment (circular cross sections 1011, 1021, 1031 in Figure 47 - three planes 124', 190', 140'), and continuing with increasing eccentricity (corresponding to increasing misalignment) of the elliptical cross sections in Figures 48, 49, and 50 (elliptical cross sections 1012, 1013, and 1014 in plane 124', elliptical cross sections 1032, 1033, and 1034 in plane 140') - and circular cross sections 1022, 1023, and 1024 in semiconductor plane 190'.

[0440] FIG. 51 shows non-overlapping SAXS patterns 1041 obtained when the incident beam was aligned with the HAR hole, and also shows overlapping SAXS patterns 1042 obtained when the incident beam was not aligned with the HAR hole.

[0441] Figure 52 shows the SAXS pattern 1043 obtained for the tall tile, which shows high divergence and low intensity.

[0442] An X-ray apparatus may be provided comprising: a mount configured to hold a sample; an X-ray source configured to direct an X-ray beam toward a first side of the sample; a detector disposed downstream of a second side of the sample during a sample measurement period and configured to detect at least a portion of the X-rays that have passed through the sample; and an X-ray intensity detector disposed at a measurement position between the X-ray source and the first side of the sample during a beam intensity monitoring period for detecting at least a portion of the X-ray beam before it reaches the sample.

[0443] The sample measurement period and the beam intensity monitoring period do not overlap.

[0444] When placed in the measurement position, the x-ray intensity detector is configured to receive the entire x-ray beam.

[0445] The X-ray device may include a mechanical mechanism configured to move the X-ray intensity detector between (a) a measurement position and (b) an outer position in which the X-ray intensity detector is positioned outside the path of the X-ray beam.

[0446] The mechanical mechanism is configured to move the X-ray intensity detector between the measurement position and the outer position by a rotational movement in a plane parallel to the first side of the sample.

[0447] The mechanical mechanism is configured to move the x-ray intensity detector between the measurement position and the outer position by a rotational movement in a plane that is not parallel to the first side of the sample.

[0448] The mechanical mechanism is configured to move the x-ray intensity detector between the measurement position and the outer position by movement of the liner in a plane parallel to the first side of the sample.

[0449] The mechanical mechanism is configured to move the x-ray intensity detector between the measurement position and the outer position by movement of the liner in a plane that is not parallel to the first side of the sample.

[0450] A beam limiter is located upstream of the measurement location, the beam limiter having at least one mechanical element configured to determine at least one of a shape of the x-ray beam and a size of a cross section of the x-ray beam.

[0451] The mechanical mechanism is configured to move the x-ray intensity detector between the measurement position and the outer position by movement parallel to the at least one mechanical element.

[0452] The mechanical mechanism is configured to move the x-ray intensity detector between the measurement position and the outer position by non-parallel movement of the at least one mechanical element.

[0453] The beam limiter comprises first and second blades having first and second edges, respectively, positioned adjacent to one another to define a slit through which the X-ray beam passes, less than 25 mm from a first side of the sample; and first and second actuators configured to shift the first and second blades along first and second translation axes, respectively, to adjust the width of the slit.

[0454] The sample measurement period and the beam intensity monitoring period partially overlap.

[0455] X-ray equipment is a semiconductor metrology tool.

[0456] A method may be provided comprising the steps of: holding the sample with a mount; directing an X-ray beam at a first side of the sample; detecting, during a sample measurement period, at least a portion of the X-rays that pass through the sample and exit from the second side with a detector positioned downstream of a second side of the sample; and detecting, during a beam intensity monitoring period, at least a portion of the X-ray beam before it reaches the sample with an X-ray intensity detector positioned at a measurement position between the X-ray source and the first side of the sample.

[0457] The sample measurement period and the beam intensity monitoring period do not overlap.

[0458] When positioned at the measurement position, the x-ray intensity detector is configured to receive the entire x-ray beam.

[0459] A mechanical mechanism configured to move the X-ray intensity detector between (a) a measurement position and (b) an outer position in which the X-ray intensity detector is positioned outside the path of the X-ray beam.

[0460] The method includes moving the X-ray intensity detector between a measurement position and an outer position by a rotational movement in a plane parallel to the first side of the sample.

[0461] The method includes moving the X-ray intensity detector between the measurement position and the outer position by a rotational movement in a plane that is not parallel to the first side of the sample.

[0462] The method includes moving an X-ray intensity detector between a measurement position and an outer position by movement of the liner in a plane parallel to the first side of the sample.

[0463] The method includes moving the X-ray intensity detector between a measurement position and an outer position by movement of the liner in a plane that is not parallel to the first side of the sample.

[0464] The method includes determining at least one of the shape of the X-ray beam and the size of the cross section of the X-ray beam by a beam limiter located upstream of the measurement location and having at least one mechanical element.

[0465] The method includes moving the x-ray intensity detector between a measurement position and an outer position by movement parallel to at least one mechanical element.

[0466] The method includes moving the x-ray intensity detector between the measurement position and the outer position by non-parallel movement of at least one mechanical element.

[0467] The beam limiter comprises first and second blades having first and second edges, respectively, positioned adjacent to one another to define a slit through which the X-ray beam passes, less than 25 mm from a first side of the sample; and first and second actuators configured to shift the first and second blades along first and second translation axes, respectively, to adjust the width of the slit.

[0468] The sample measurement period and the beam intensity monitoring period overlap.

[0469] A non-transitory computer readable medium storing the following instructions may be provided: holding the sample with a mount; directing an X-ray beam at a first side of the sample; during a sample measurement period, detecting at least a portion of the X-rays that pass through the sample and exit from the second side with a detector positioned downstream of the second side of the sample; and during a beam intensity monitoring period, detecting at least a portion of the X-ray beam before it reaches the sample with an X-ray intensity detector positioned at a measurement position between the X-ray source and the first side of the sample.

[0470] An X-ray device may be provided comprising: a mount configured to hold a sample; an X-ray source configured to direct an X-ray beam towards a first side of the sample; a small angle X-ray scattering (SAXS) detector disposed downstream of a second side of the sample and configured to detect at least a portion of a SAXS pattern formed by X-rays passing through the sample and exiting the second side; and an X-ray fluorescence (XRF) detector having an aperture and configured to detect fluorescent X-rays emitted from the sample.

[0471] An XRF detector is positioned upstream of the first side of the sample.

[0472] The XRF detector includes an aperture, and the X-ray source is configured to direct an X-ray beam through the aperture.

[0473] An XRF detector is positioned within 5 millimeters of the first side of the sample.

[0474] An XRF detector is positioned downstream on a second side of the sample.

[0475] The opening is shaped and dimensioned to allow at least a portion of the SAXS pattern to reach the SAXS detector.

[0476] An additional x-ray source configured to direct another x-ray beam through the aperture.

[0477] An XRF detector is shaped and positioned to detect fluorescent X-rays emitted from the sample over a large solid angle.

[0478] The XRF detector has at least one independent radiation sensing segment.

[0479] The XRF detector includes at least one independent silicon drift detector.

[0480] A method may be provided comprising the steps of: holding a sample with a mount; directing an X-ray beam at a first side of the sample; detecting at least a portion of a SAXS pattern formed by X-rays passing through the sample, passing through the sample and exiting the second side with a small angle X-ray scattering (SAXS) detector positioned downstream of a second side of the sample; and detecting fluorescent X-rays emitted from the sample with an X-ray fluorescence (XRF) detector having an aperture.

[0481] An XRF detector is positioned upstream of the first side of the sample.

[0482] The XRF detector includes an aperture and the method includes directing, by an X-ray source, an X-ray beam through the aperture.

[0483] An XRF detector is positioned within 5 millimeters of the first side of the sample.

[0484] An XRF detector is positioned downstream on a second side of the sample.

[0485] The opening is shaped and dimensioned to allow at least a portion of the SAXS pattern to reach the SAXS detector.

[0486] An additional x-ray source is configured to direct another x-ray beam through the opening.

[0487] An XRF detector is shaped and positioned to detect fluorescent X-rays emitted from the sample over a large solid angle.

[0488] The XRF detector has at least one independent radiation sensing segment.

[0489] The XRF detector includes at least one independent silicon drift detector.

[0490] A non-transitory computer readable medium storing the following instructions may be provided: holding the sample with a mount; directing an X-ray beam at a first side of the sample; detecting at least a portion of a SAXS pattern formed by the X-rays passing through the sample and exiting the sample from the second side with a small angle X-ray scattering (SAXS) detector positioned downstream of a second side of the sample; and detecting fluorescent X-rays emitted from the sample with an X-ray fluorescence (XRF) detector having an aperture.

[0491] A method may be provided for determining an orientation of an array of high aspect ratio (HAR) structures in a sample, comprising: acquiring different small angle X-ray scattering (SAXS) patterns for at least one of different angular or in-plane spatial relationships between the sample and an X-ray beam illuminating the sample; where each SAXS pattern represents an angular intensity distribution of scattered X-rays detected by a SAXS sensor; calculating, for at least some of the different SAXS patterns, at least one sum of intensities within at least one angular range of the angular intensity distribution to provide a first plurality of sums; and determining an orientation of an array of HAR holes based on the at least the first plurality of sums.

[0492] The determining step includes comparing the first plurality of sums to a reference sum associated with a known orientation of the sequence of the HAR holes.

[0493] The calculating step comprises calculating at least one sum of intensities within at least one angular range for all the different SAXS patterns.

[0494] The calculating step comprises calculating two or more total intensities in two or more angular ranges of the angular intensity distribution by calculating for one or more different SAXS patterns.

[0495] Obtaining the different SAXS patterns comprises rotating the sample relative to an X-ray beam that irradiates the sample to provide the different SAXS patterns.

[0496] Obtaining the different SAXS patterns comprises rotating an X-ray beam relative to the sample that irradiates the sample to provide the different SAXS patterns.

[0497] A non-transitory computer-readable medium may be provided that stores instructions for: acquiring different small-angle X-ray scattering (SAXS) patterns for different angular and / or in-plane spatial relationships between a sample including an array of high aspect ratio (HAR) holes and an X-ray beam illuminating the sample; where each SAXS pattern represents an angular intensity distribution of scattered X-rays detected by a SAXS sensor; calculating, for at least some of the different SAXS patterns, at least one sum of intensities within at least one angular range of the angular intensity distribution to provide a first plurality of sums; and determining an orientation of the array of HAR holes based on the at least the first plurality of sums.

[0498] The determining step includes comparing the first plurality of sums to a reference sum associated with a known orientation of the sequence of the HAR holes.

[0499] The calculating step comprises calculating at least one sum of intensities within at least one angular range for all the different SAXS patterns.

[0500] The calculating step comprises calculating two or more total intensities in two or more angular ranges of the angular intensity distribution by calculating for one or more different SAXS patterns.

[0501] Obtaining the different SAXS patterns comprises rotating the sample relative to an X-ray beam that irradiates the sample to provide the different SAXS patterns.

[0502] Obtaining the different SAXS patterns comprises rotating an X-ray beam relative to the sample that irradiates the sample to provide the different SAXS patterns.

[0503] An apparatus may be provided comprising: a mount configured to hold a sample including an array of high aspect ratio (HAR) holes; X-ray optics configured to acquire different small angle X-ray scattering (SAXS) patterns for different angular relationships between the sample and an X-ray beam irradiating the sample; where each SAXS pattern represents an angular intensity distribution of scattered X-rays detected by a SAXS sensor; and a processor configured to (a) calculate at least one sum of intensities within at least one angular range of the angular intensity distributions for at least some of the different SAXS patterns to provide a first plurality of sums; and (b) determine an orientation of the array of HAR holes based on the first plurality of sums.

[0504] The determining step includes comparing the first plurality of sums to a reference sum associated with a known orientation of the sequence of the HAR holes.

[0505] The calculating step comprises calculating at least one sum of intensities within at least one angular range for all the different SAXS patterns.

[0506] The calculating step comprises calculating two or more total intensities in two or more angular ranges of the angular intensity distribution by calculating for one or more different SAXS patterns.

[0507] Obtaining the different SAXS patterns comprises rotating the sample relative to an X-ray beam that irradiates the sample to provide the different SAXS patterns.

[0508] Obtaining the different SAXS patterns comprises rotating an X-ray beam relative to the sample that irradiates the sample to provide the different SAXS patterns.

[0509] A method for determining the orientation and shape of an array of high aspect ratio (HAR) structures in a sample may be provided, comprising: irradiating the sample with an X-ray beam while the X-ray beam is substantially parallel to the HAR holes of the array; wherein the sample further has one or more additional repeating structures; wherein an aspect ratio of the structural elements forming the one or more additional repeating structures is much smaller than the aspect ratio of the HAR holes; detecting a first small angle X-ray scattering (SAXS) pattern with a SAXS detector; modifying the spatial relationship between the sample and the optical axis of the X-ray beam; irradiating the sample with the X-ray beam while the X-ray beam is substantially oblique to the HAR holes of the array; detecting a second SAXS pattern with the SAXS detector; determining a relationship between the first and second SAXS patterns; and generating information regarding the array of HAR holes based on the relationship between the first and second SAXS patterns.

[0510] The one or more additional repeat structures are substantially parallel to the sequence of the HAR holes.

[0511] Varying the spatial relationship includes altering the spatial relationship between the X-ray beam and the sample to substantially eliminate the effect of alignment on the second SAXS pattern.

[0512] The step of altering the spatial relationship comprises rotating the sample.

[0513] Varying the spatial relationship includes rotating the x-ray beam.

[0514] The method includes estimating a combined effect of the additional repeating structures and the backscattered X-ray radiation based on the relationship.

[0515] By deviating from perfect alignment with the longitudinal axes of the HAR holes by up to 2 degrees, the x-ray beam is substantially parallel to the HAR holes of the array.

[0516] A non-transitory computer readable medium may be provided that stores instructions for: irradiating the sample with an X-ray beam while the X-ray beam is substantially parallel to a high aspect ratio (HAR) hole of an array of HAR holes belonging to the sample; wherein the sample further has one or more additional repeating structures; wherein an aspect ratio of structural elements forming the one or more additional repeating structures is much smaller than an aspect ratio of the HAR holes; detecting a first small angle X-ray scattering (SAXS) pattern with a SAXS detector; modifying a spatial relationship between the sample and an optical axis of the X-ray beam; irradiating the sample with the X-ray beam while the X-ray beam is substantially oblique to the HAR holes of the array; detecting a second SAXS pattern with a SAXS detector; determining a relationship between the first and second SAXS patterns; and generating information regarding the array of HAR holes based on the relationship between the first and second SAXS patterns.

[0517] The one or more additional repeat structures are substantially parallel to the sequence of the HAR holes.

[0518] Varying the spatial relationship includes altering the spatial relationship between the X-ray beam and the sample to substantially eliminate the effect of alignment on the second SAXS pattern.

[0519] The step of altering the spatial relationship comprises rotating the sample.

[0520] Varying the spatial relationship includes rotating the x-ray beam.

[0521] and storing instructions for estimating a combined effect of the additional repetitive structures and the backscattered X-ray radiation based on the relationship.

[0522] By deviating from perfect alignment with the longitudinal axes of the HAR holes by up to 2 degrees, the x-ray beam is substantially parallel to the HAR holes of the array.

[0523] a mount configured to hold a sample having an array of high aspect ratio (HAR) holes and having one or more additional repeating structures; wherein an aspect ratio of structural elements forming the one or more additional repeating structures is much smaller than an aspect ratio of the HAR holes; and an X-ray optical system for (i) irradiating the sample with an X-ray beam while the X-ray beam is substantially parallel to the high aspect ratio (HAR) holes of the array of HAR holes, (ii) detecting a first small angle X-ray scattering (SAXS) pattern with a SAXS detector, and (iii) An apparatus may be provided comprising: X-ray optics configured to: (iv) vary a spatial relationship between the sample and an optical axis of the X-ray beam; (iv) irradiate the sample with the X-ray beam while the X-ray beam is substantially oblique to the array of HAR holes; and (v) detect a second SAXS pattern with the SAXS detector; and a processor configured to: (i) determine a relationship between the first and second SAXS patterns; and (ii) generate information about the array of HAR holes based on the relationship between the first and second SAXS patterns.

[0524] The one or more additional repeat structures are substantially parallel to the sequence of the HAR holes.

[0525] Varying the spatial relationship includes altering the spatial relationship between the X-ray beam and the sample to substantially eliminate the effect of alignment on the second SAXS pattern.

[0526] The step of altering the spatial relationship comprises rotating the sample.

[0527] Varying the spatial relationship includes rotating the x-ray beam.

[0528] The method further comprises estimating a combined effect of the additional repeating structures and the backscattered X-ray radiation based on the relationship.

[0529] By deviating from perfect alignment with the longitudinal axes of the HAR holes by up to 2 degrees, the x-ray beam is substantially parallel to the HAR holes of the array.

[0530] There may be provided a method for evaluating a sample including an array of structural elements, comprising: acquiring a first small angle X-ray scattering (SAXS) pattern for a first angular relationship between the sample and an X-ray beam exhibiting a first collimation value; and acquiring a second SAXS pattern for a second angular relationship between the sample and an X-ray beam exhibiting a second collimation value different from the first collimation value, wherein acquiring the first and second SAXS patterns comprises substantially maintaining an X-ray cross-section of a first side of the sample during acquisition of the first and second SAXS patterns.

[0531] The method may include acquiring at least one additional SAXS pattern for at least one additional angular relationship between the sample and the X-ray beam; where each additional angular relationship, the first and second angular relationships, is different from one another; and where acquiring each additional SAXS pattern may include substantially maintaining an X-ray cross-sectional area of ​​a first side of the sample while varying collimation of the X-ray beam.

[0532] The method may include evaluating the sample based on at least the first and second SAXS patterns.

[0533] The steps of acquiring the first SAXS pattern and acquiring the second SAXS pattern further differ from each other by the intensity of the X-ray beam.

[0534] The X-ray beam has a circular cross section, and the difference between the first and second collimation values ​​determines the eccentricity of the diffraction orders of the first and second SAXS patterns.

[0535] The first angular relationship is a first illumination angle and the second angular relationship is a second illumination angle, where the second illumination angle is greater than the first illumination angle and the first collimation value represents an X-ray beam that is more collimated than an X-ray beam having the second collimation value.

[0536] The method may include determining a second collimation value based on at least a signal-to-noise ratio associated with the second SAXS pattern.

[0537] The method can include determining a second collimation value based at least on an expected overlap between lobes of the second SAXS pattern.

[0538] The method may include determining a second collimation value based on information obtained from the first SAXS pattern.

[0539] The method may include determining a second collimation value based on a priority or importance of an arrangement of the structural elements.

[0540] A non-transitory computer readable medium may be provided having instructions for: acquiring a first small angle X-ray scattering (SAXS) pattern for a first angular relationship between a sample and an X-ray beam exhibiting a first collimation value, the sample having an array of structural elements; and acquiring a second SAXS pattern for a second angular relationship between the sample and the X-ray beam exhibiting a second collimation value different from the first collimation value, where acquiring the first and second SAXS patterns includes substantially maintaining an X-ray cross-sectional area of ​​a first side of the sample during acquisition of the first and second SAXS patterns.

[0541] The non-transitory computer readable medium has instructions for acquiring at least one additional SAXS pattern for at least one additional angular relationship between the sample and the X-ray beam; where each additional angular relationship, the first and second angular relationships, are different from one another; and where acquiring each additional SAXS pattern includes substantially maintaining an X-ray cross-sectional area of ​​a first side of the sample while varying collimation of the X-ray beam.

[0542] The non-transitory computer readable medium has instructions for evaluating the sample based on at least the first and second SAXS patterns.

[0543] The steps of acquiring the first SAXS pattern and acquiring the second SAXS pattern further differ from each other by the intensity of the X-ray beam.

[0544] The X-ray beam has a circular cross section, and the difference between the first and second collimation values ​​determines the eccentricity of the diffraction orders of the first and second SAXS patterns.

[0545] The first angular relationship is a first illumination angle and the second angular relationship is a second illumination angle, where the second illumination angle is greater than the first illumination angle and the first collimation value represents an X-ray beam that is more collimated than an X-ray beam having the second collimation value.

[0546] The method further comprises instructions for determining a second collimation value based on at least a signal-to-noise ratio associated with the second SAXS pattern.

[0547] and instructions for determining a second collimation value based at least on an expected overlap between lobes of the second SAXS pattern.

[0548] The method further comprises the step of: determining a second collimation value based on information obtained from the first SAXS pattern.

[0549] The method further comprises the step of: determining a second collimation value based on a priority or importance of the arrangement of the structural elements.

[0550] 1. An X-ray apparatus comprising: a mount for holding a sample including an array of structural elements; An X-ray apparatus may be provided comprising: X-ray optics configured to acquire a first small angle X-ray scattering (SAXS) pattern for a first angular relationship between the sample and an X-ray beam exhibiting a first collimation value; and acquire a second small angle X-ray scattering (SAXS) pattern for a second angular relationship between the sample and an X-ray beam exhibiting a second collimation value different from the first collimation value; where the second angular relationship is different from the first angular relationship, and where acquiring the first and second SAXS patterns comprises substantially maintaining an X-ray cross-sectional area of ​​a first side of the sample during acquisition of the first and second SAXS patterns.

[0551] The x-ray device has a processor configured to evaluate the sample based on at least the first and second SAXS patterns.

[0552] A processor configured to determine a second collimation value based on at least a signal-to-noise ratio associated with the second SAXS pattern.

[0553] A processor configured to determine a second collimation value based at least on an expected overlap between the lobes of the second SAXS pattern.

[0554] A processor configured to determine a second collimation value based on information obtained from the first SAXS pattern.

[0555] A processor is configured to determine a second collimation value based on a priority or importance of the arrangement of the structural elements.

[0556] configured to acquire at least one additional SAXS pattern for at least one additional angular relationship between the sample and the X-ray beam, where each additional angular relationship, the first and second angular relationships, are different from one another, and where acquiring each additional SAXS pattern includes substantially maintaining an X-ray cross-sectional area of ​​a first side of the sample while varying collimation of the X-ray beam.

[0557] The steps of acquiring a first SAXS pattern and acquiring a second SAXS pattern further differ from each other by an intensity of the X-ray beam.

[0558] The X-ray beam has a circular cross section, and the difference between the first and second collimation values ​​determines the eccentricity of the diffraction orders of the first and second SAXS patterns.

[0559] The first angular relationship is a first illumination angle and the second angular relationship is a second illumination angle, where the second illumination angle is greater than the first illumination angle and the first collimation value represents an X-ray beam that is more collimated than an X-ray beam having the second collimation value.

[0560] The term "configured" may mean "constructed or arranged."

[0561] References to "comprising" should apply mutatis mutandis to "consisting of" and "consisting essentially of".

[0562] Any combination of any steps of any method may be provided, and thus steps from more than one method may be part of a method covered by this application.

[0563] Any combination of instructions stored on a non-transitory computer readable medium may be provided. Thus, the computer readable medium may store instructions for performing any combination of the steps of one or more of the methods set forth herein.

[0564] Any combination of any of the components illustrated in this application (eg, sensors, optics, mechanical elements, detectors, etc.) may be provided.

[0565] Any reference to any one of the methods, apparatus (including X-ray apparatus), and non-transitory computer readable medium should apply mutatis mutandis to any other one of the methods, apparatus (including X-ray apparatus), and non-transitory computer readable medium.

[0566] The drawings may or may not be to scale.

[0567] Although the embodiments described herein primarily address X-ray analysis of single crystal, polycrystalline, or amorphous samples such as semiconductor wafers, the methods and systems described herein can also be used in other technological applications of arrays of nanostructures.

[0568] Therefore, the above embodiments are cited as examples, and it will be understood that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art that would occur to a person skilled in the art upon reading the foregoing description. Documents incorporated by reference into this patent application should be considered as an integral part of this application. In the event of a discrepancy between the definition of a term expressly or implicitly made in this specification and the definition of a term in these incorporated documents, the definition in this specification should be considered.

Claims

1. 1. An X-ray apparatus comprising: a mount configured to hold a sample; an X-ray source configured to direct an X-ray beam at a first side of the sample; a small angle x-ray scattering (SAXS) detector disposed downstream of the second side of the sample and configured to detect at least a portion of a SAXS pattern formed by x-rays passing through the sample and exiting the second side; an X-ray fluorescence (XRF) detector configured to detect X-ray fluorescence emitted from the sample, the XRF detector having an aperture; 1. An X-ray apparatus comprising:

2. 2. The x-ray device of claim 1, wherein the XRF detector is positioned upstream of the first side of the sample.

3. 3. The x-ray device of claim 2, wherein the XRF detector includes an aperture, and the x-ray source is configured to direct the x-ray beam such that the x-ray beam passes through the aperture.

4. 3. The x-ray device of claim 2, wherein the XRF detector is positioned less than 5 millimeters from the first side of the sample.

5. 2. The x-ray device of claim 1, wherein the XRF detector is positioned downstream of the second side of the sample.

6. 2. The x-ray device of claim 1, wherein the opening is shaped and sized to allow at least a portion of the SAXS pattern to reach the SAXS detector.

7. 10. The x-ray device of claim 1, further comprising an additional x-ray source configured to direct another x-ray beam through the opening.

8. 2. The x-ray device of claim 1, wherein the XRF detector is shaped and positioned to detect the x-ray fluorescence emitted from the sample over a large solid angle.

9. 2. The X-ray device of claim 1, wherein the XRF detector comprises at least one independent radiation-sensing segment.

10. 2. The x-ray device of claim 1, wherein the XRF detector comprises at least one independent silicon drift detector.

11. holding the sample with a mount; directing an X-ray beam at a first side of the sample; detecting at least a portion of a SAXS pattern formed by X-rays passing through the sample and exiting the second side with a small angle X-ray scattering (SAXS) detector positioned downstream of the second side of the sample; and detecting x-ray fluorescence emitted from the sample with an x-ray fluorescence (XRF) detector having an aperture; The method according to claim 1, further comprising:

12. 12. The method of claim 11, wherein the XRF detector is positioned upstream of the first side of the sample.

13. 13. The method of claim 12, wherein the XRF detector includes an aperture, the method comprising directing, by the X-ray source, the X-ray beam through the aperture.

14. 13. The method of claim 12, wherein the XRF detector is positioned less than 5 millimeters from the first side of the sample.

15. 12. The method of claim 11, wherein the XRF detector is positioned downstream of the second side of the sample.

16. 12. The method of claim 11, wherein the opening is shaped and sized to allow at least a portion of the SAXS pattern to reach the SAXS detector.

17. 12. The method of claim 11, further comprising an additional x-ray source configured to direct another x-ray beam through the opening.

18. 12. The method of claim 11, wherein the XRF detector is shaped and positioned to detect the x-ray fluorescence emitted from the sample over a large solid angle.

19. The method of claim 11 , wherein the XRF detector comprises at least one independent radiation-sensing segment.

20. 12. The method of claim 11, wherein the XRF detector comprises at least one independent silicon drift detector.

21. holding the sample with a mount; directing an X-ray beam at a first side of the sample; detecting, with a small angle X-ray scattering (SAXS) detector positioned downstream of the second side of the sample, at least a portion of a SAXS pattern formed by X-rays passing through the sample and exiting the sample from the second side; and detecting x-ray fluorescence emitted from the sample with an x-ray fluorescence (XRF) detector having an aperture; A non-transitory computer readable medium storing instructions for executing the method.

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