3D profilometry with Linnik interferometer

Abstract

Systems and methods for generating volumetric data are disclosed that can scan a sample at multiple focal planes located along the depth of the sample. A detector in a metrology subsystem can generate multiple images of a volumetric field of the sample at the multiple focal planes. The systems and methods can aggregate the multiple images to generate volumetric data for the volumetric field of the sample. The metrology subsystem can include a Linnik interferometer.

Description

[Technical Field]

[0001] The present disclosure relates generally to interferometric metrology, and more particularly to interferometric metrology of bond pad geometry and post-bond specimen voids. [Background technology]

[0002] The ever-increasing demand for physical density in semiconductor devices has led to a trend toward ever-increasing complexity in three-dimensional integrated circuit (3D-IC) design. This trend involves optimizing processes for specialized functions (e.g., 3D-NAND devices, complementary metal-oxide semiconductor image sensor (CIS) devices, logic gates, such as AND gates, tailored for specific device types) by fabricating those types of devices on separate substrates and then combining those substrates into a single (3D-bonded) structure (e.g., by wafer-to-wafer (W2W) bonding, die-to-die (D2D) bonding, die-to-wafer (D2W) bonding, etc.). For example, the combination can be temporary and / or permanent. Furthermore, the combination can be collective and / or direct. For example, collective can refer to collective D2W (Co-D2W) bonding of multiple bonded dies in a single placement operation, and direct can refer to sequential pick-and-place of individual dies.

[0003] One approach to achieving 3D-IC design is to fabricate structures on two separate specimens and then bond them together using structures (such as interconnects and devices) near the interface. This technique facilitates the integration of complex structures by fabricating the two specimens separately and then bonding them in a subsequent process. This trend is also driven by the desire to overcome communication bottlenecks between different functions and areas within a specimen by creating dense interconnects between the bonded specimens. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2014 / 0029014 [Patent Document 2] U.S. Patent Application Publication No. 2018 / 0059032 [Patent Document 3] U.S. Patent Application Publication No. 2020 / 0240765 Summary of the Invention [Problem to be solved by the invention]

[0005] However, defects can cause voids (gaps) between the bonded surfaces. Examples of defects include unwanted bumps, ridges, foreign particles, etc. For example, a particle smaller than 1 micron (= 1 μm) can cause a void several tens of microns in size.

[0006] Some 3D-IC technologies impose stringent requirements on the surfaces of the specimens to be bonded, mandating tight bonding specifications to support tighter interconnect densities and smaller features with tighter overlay alignment tolerances. As part of the bonding process, the surfaces to be bonded are made concave, allowing temporary voids to form between them. These gaps are then closed before the surfaces are joined using a heat and pressure bonding process. Characterization of the pad geometry is typically performed prior to bonding using atomic force microscopy (AFM). [Means for solving the problem]

[0007] A metrology system is disclosed in accordance with one or more embodiments of the present disclosure. The metrology system of an exemplary embodiment includes a metrology subsystem. In an exemplary embodiment, the metrology subsystem includes a detector configured for multi-pixel imaging. In an exemplary embodiment, the metrology subsystem includes an illumination source configured to generate an illumination beam. In an exemplary embodiment, the metrology subsystem includes a beam splitter configured to split the illumination beam into a measurement beam propagating in a measurement arm and a reference beam propagating in a reference arm. In an exemplary embodiment, the metrology subsystem includes a metrology objective configured to direct the measurement beam toward the sample. In an exemplary embodiment, the metrology subsystem includes one or more illumination optics configured to illuminate a volumetric field of the sample with the measurement beam through the measurement objective. In an exemplary embodiment, the metrology subsystem includes a reference objective configured to direct a reference beam toward a reference sample. In an exemplary embodiment, the metrology subsystem includes a controller communicatively coupled to the detector. In some exemplary embodiments, the controller may include one or more processors and may include a memory. In some exemplary embodiments, the one or more processors are configured to execute a set of program instructions stored on the memory. In some exemplary embodiments, the one or more processors are configured to execute program instructions that cause the one or more processors to receive a plurality of images resulting from scanning the specimen at a plurality of focal planes along the specimen depth, and to generate a plurality of images of a volumetric field of the specimen at the plurality of focal planes using detectors in the metrology subsystem. In some exemplary embodiments, the one or more processors are configured to execute program instructions that cause the one or more processors to aggregate the plurality of images to generate volumetric data of the volumetric field of the specimen.

[0008] A method is disclosed in accordance with one or more embodiments of the present disclosure. In an exemplary embodiment, the method may include, but is not limited to, fabricating a specimen according to a manufacturing process, and the specimen having a concave surface profile. In an exemplary embodiment, the method may generate volumetric data of the specimen's surface profile using a metrology subsystem including a detector, and the metrology subsystem may include a Linnik interferometer and the detector may include a multi-pixel detector. In an exemplary embodiment, the method may couple the specimen having the surface profile to a second specimen configured to be coupled to the specimen. In an exemplary embodiment, the method may adjust the manufacturing process based on the volumetric data.

[0009] Another method is disclosed in accordance with one or more embodiments of the present disclosure. In one exemplary embodiment, the method includes, but is not limited to, scanning a specimen at multiple focal planes located along the depth of the specimen, thereby generating multiple images of the volumetric field of the specimen at the multiple focal planes using a detector in a metrology subsystem, which may include a multi-pixel detector. In one exemplary embodiment, the method includes combining the multiple images to generate volumetric data for the volumetric field of the specimen.

[0010] Both the foregoing general description and the following detailed description are exemplary and explanatory only and do not necessarily limit the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description, serve to explain the principles of the invention.

[0011] Those skilled in the art can better appreciate the numerous advantages of the present disclosure by reviewing the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1A]FIG. 1 is a conceptual diagram illustrating a weighing system according to one or more embodiments of the present disclosure. [Figure 1B] FIG. 1 is a conceptual diagram of an image-based metrology subsystem in accordance with one or more embodiments of the present disclosure. [Figure 1C] FIG. 1 is a schematic diagram of a metrology subsystem having a Linnik interferometer-based specimen positioning subsystem in accordance with one or more embodiments of the present disclosure. [Figure 1D] FIG. 10 is a schematic ray diagram illustrating oblique illumination propagation within a metrology subsystem in accordance with one or more embodiments of the present disclosure. [Figure 1E] FIG. 1 is a schematic diagram of a metrology subsystem imaging voids in a post-bonded specimen, in accordance with one or more embodiments of the present disclosure. [Figure 1F] FIG. 10 is a schematic diagram of a metrology subsystem imaging pad geometry on a post-temporary bonding specimen, in accordance with one or more embodiments of the present disclosure. [Figure 1G] FIG. 1 is a schematic diagram of a metrology subsystem imaging a through silicon via (TSV) of a post-bond specimen, in accordance with one or more embodiments of the present disclosure. [Figure 1H] FIG. 1 is a schematic diagram of a metrology subsystem imaging a target on a specimen, in accordance with one or more embodiments of the present disclosure. [Figure 2] FIG. 10 is a diagram of a 3D volumetric topology profile of an embedded volumetric field of a specimen reconstructed from interferometry tool data, according to one or more embodiments of the present disclosure. [Figure 3] FIG. 1 is a flow diagram depicting steps performed in a volumetric data generation method according to one or more embodiments of the present disclosure. [Figure 4] FIG. 1 is a flow diagram depicting steps performed in a volumetric data generation method according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Reference will now be made in detail to the disclosed subject matter, which is illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with reference to certain embodiments and particular features thereof. The embodiments described herein are to be considered illustrative rather than limiting. Various changes and modifications in form and detail may be made without departing from the spirit and scope of the present disclosure.

[0014] Embodiments of the present disclosure are directed to systems and methods for using a metrology subsystem (e.g., an interferometer, a Linnik interferometer, etc.) to identify a volumetric field, including voids, at an interface of a bonded specimen and / or measure the surface of a temporarily bonded specimen. Certain embodiments of the present disclosure are directed to scanning the interface of a bonded specimen by acquiring multiple images along the depth of the bonded specimen, using a Linnik interferometer adapted for infrared (e.g., but not limited to, shortwave infrared (SWIR), near infrared (NIR), etc.) imaging, generating volumetric data based on the images, and using the images to identify and / or characterize the volumetric field of the specimen. Certain embodiments of the present disclosure are directed to using a Linnik interferometer in the visible light spectrum to generate volumetric data of the surface topography of the temporarily bonded specimen.

[0015] One technique for imaging embedded volumetric fields in post-bond specimens (e.g., wafer-to-wafer (W2W) bonded specimens) is acoustic microscopy via an acoustic microscope. However, acoustic microscopy can be limited in lateral resolution to approximately 50 microns or greater. Another technique uses patterned wafer geometry (PWG) tools, which can also be limited in resolution. The advantage of acoustic microscopy and PWG tools is that they generally perform well for large-area inspection, but they can have low sensitivity to individual device features, making them impractical for final inspection of such features. It should also be noted that post-bond specimen voids (e.g., those caused by surface defects, particles / dust, etc.) can be on the order of tens of microns (or less). It is contemplated herein that such voids... due to the decreasing feature sizes and tightening tolerance requirements in 3D-ICs... may cause problems (e.g., malfunction of devices / features on the specimen, lack of desired interconnects between bonded specimens, specification / tolerance violations of bonded specimens, etc.) Therefore, it is contemplated herein that acoustic microscopy may not have sufficient resolution to detect such potential problems within a volumetric view of the specimen.

[0016] Topographic metrology of specimens after temporary bonding can present challenges. Some processes allow for proper bonding by creating a concave topography on the surface of a wafer, die, etc. In such a setup, the concave surfaces of the specimens to be temporarily bonded can be interlocked such that a gap is formed upon bonding of the specimen with the topography to a second specimen configured to bond to the first specimen. Such a gap can be closed / collapsed by the heat and pressure of the bonding process.

[0017] As the trend toward higher density of devices and interconnects on specimens grows, the tolerances required for the surface topography of the bonded specimens will become tighter. One technique for measuring the surface topography of bonded specimens uses atomic force microscopy (AFM). AFMs typically have high resolution but are slower than other metrology techniques.

[0018] Embodiments of the present disclosure may be faster, more efficient, and offer a better compromise between resolution and imaging speed than other techniques (e.g., AFM). For example, even when the resolution of embodiments of the present disclosure is lower than that of AFM, the compromise between increased imaging speed and the ability to image at a particular resolution (e.g., within an acceptable tolerance) may provide a suitable solution. For example, imaging the surface topography of a specimen after temporary bonding using a Linnik interferometer in the visible light spectrum may provide an excellent compromise, offering one or more benefits over previous techniques.

[0019] According to various embodiments, the Linnik interferometer can be used to speed up volumetric data generation (e.g., volumetric profilometry) searches, including but not limited to, at speeds of 300 milliseconds or less (per volumetric field of view of the measured specimen). According to certain examples, volumetric data generation can occur at speeds of 10 milliseconds or less per volumetric field of view of the measured specimen. According to certain examples, volumetric data generation searches can be performed with sub-micron accuracy / precision / resolution. Such resolution may be appropriate for measuring the shape of the temporary bonded surface and / or measuring voids embedded in the bonded specimen interface.

[0020] Embodiments of the present disclosure are directed to systems and methods for performing metrology on a volumetric field of view, scanning along a depth direction using a metrology subsystem and generating volumetric data based on images generated from the scan. It should be noted that using an imaging subsystem to capture images of buried targets in a post-cementation specimen is disclosed in U.S. Patent Application No. 17 / 069,177, entitled "IMAGING SYSTEM FOR BURIED METROLOGY TARGETS," filed October 13, 2020 (hereinafter "U.S. Patent Application No. 17 / 069,177"), which is incorporated herein by reference in its entirety.

[0021] Benefits of at least certain embodiments of the present disclosure may include volumetric data generation, improved resolution, reduced imaging time, and / or the like. The imaging time may be defined as the time required to obtain measurements for each volumetric field of a specimen, including focusing, image capture, alignment, and the like. For example, the imaging time may be defined in the context of a scanning configuration and / or a move-acquire-measure (MAM) configuration. For example, in a scanning configuration, a time delay integration (TDI) detector may be used to acquire images and generate volumetric data, and the imaging time may be calculated by dividing the time required to image multiple points of interest by the number of points of interest. For example, in certain embodiments, the imaging time may be several hundred (e.g., 100-200) milliseconds or less (e.g., less than 100 milliseconds) per measured volumetric field of view, e.g., several hundred milliseconds per feature distributed over a 40 micron by 40 micron area of a specimen after temporary cementation. According to certain embodiments, the metrology subsystem can achieve resolutions of 5 microns, 3 microns, as low as 1 micron, and / or the like.

[0022] As used throughout this disclosure, the terms "specimen" or "substrate" refer generally to a substrate. For example, a substrate can be formed of a semiconductor or non-semiconductor material. In certain examples, the substrate can be a wafer, a die, or the like. For example, semiconductor or non-semiconductor materials can include, but are not limited to, monocrystalline silicon, gallium arsenide, and indium phosphide. A specimen can have one or more layers. For example, such layers can include, but are not limited to, resist (e.g., photoresist), dielectric material, conductive material, and semiconductor material. Many different types of such layers are known in the art, and the term specimen, as used herein, is intended to encompass a specimen upon which any such layer may be formed. The one or more layers formed on the specimen can be patterned or unpatterned. For example, a specimen can include multiple dies, each having repetitive patterned features. The formation and processing of such material layers can ultimately result in a completed device. Many different types of devices may be formed on a specimen, and the term specimen, as used herein, is intended to encompass a specimen upon which any type of device known in the art may be fabricated. Furthermore, for purposes of this disclosure, the terms specimen and wafer should be interpreted interchangeably, to the extent that a specimen can be a wafer, and a wafer is at least one example of a specimen. A die is another example of a specimen.

[0023] 1A-1F, systems and methods for imaging a specimen 106 to generate volumetric data are described below in accordance with one or more embodiments of the present disclosure. In accordance with at least certain embodiments, the systems and methods can be used to augment existing specimen metrology (e.g., overlay metrology) and / or inspection systems and methods.

[0024] FIG. 1A depicts a conceptual diagram of a metrology system 100 according to one or more embodiments of the present disclosure. The metrology system 100 of one embodiment includes a metrology subsystem 102 configured to scan at least one volumetric field of view 104 of a specimen 106. For example, the metrology subsystem 102 may generate multiple field plane images of the volumetric field 104 and / or multiple pupil plane images of the embedded volumetric field 104. For example, 50 or more images, 80 or more images, etc., may be sufficient to generate adequate volumetric data along a depth direction. Additionally, the metrology system 100 of one embodiment includes a metrology subsystem 102 configured to scan at least one surface feature (e.g., surface 160) of the specimen 106. In general, the volumetric field 104 may be located at and / or encompass any area, surface, volume, defect, target, void, and / or the like.

[0025] In various embodiments, specimen 106 may include any type of specimen known in the art. For example, specimen 106 may include a bonded specimen formed of two substrates bonded together at an interface, with volumetric field of view 104 located at or near the interface. Furthermore, specimens may be formed of any material or combination of materials, including, but not limited to, semiconductor, metal, polymer, glass, or crystalline materials. In some embodiments, at least one of the specimens may include a wafer (e.g., a semiconductor wafer). For example, specimen 106 may be formed as a bonded wafer specimen, with two wafers bonded together at an interface.

[0026] In some embodiments, specimen 106 is a die-to-wafer (D2W) bonded specimen. For example, metrology system 100, metrology subsystem 102, and / or interferometers may be configured to operate on a die-to-wafer specimen (e.g., a bonded die-to-wafer specimen, a temporary bonded die configured to be bonded to a wafer, and / or the like) according to a metrology recipe.

[0027] In some embodiments, specimen 106 is a die-to-die (D2D) bonded specimen.

[0028] In some embodiments, specimen 106 is a wafer-to-wafer (W2W) bonded specimen.

[0029] In some embodiments, specimen 106 is a die-to-wafer (D2W) bonded specimen.

[0030] The metrology subsystem 102 may include any type of metrology subsystem known in the art that is adapted to generate one or more images of one or more volumetric fields 104 on the specimen 106 at any plane (e.g., a focal plane) or combination of planes, and to measure one or more parameters of interest related to the specimen 106 based on the one or more images.

[0031] In some embodiments, the weighing system 100 also includes a controller 108 communicatively coupled to the weighing subsystem 102. In some embodiments, the controller 108 also includes one or more processors 110 configured to execute program instructions stored on a memory 112. The one or more processors 110 included in the controller 108 may include any processing element known in the art. In this regard, the one or more processors 110 may include any microprocessor-based device configured to execute algorithms and / or instructions. The memory 112 may further include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 110. For example, the memory 112 may include a non-transitory storage medium. As additional examples, the memory 112 may include, but is not limited to, read-only memory (ROM), random access memory (RAM), magnetic or optical memory (e.g., disk), magnetic tape, solid-state drive, etc. It is further noted that memory 112 may be housed along with one or more processors 110 within a common controller housing.

[0032] In this case, one or more processors 110 included in the controller 108 may perform any of the various process steps described elsewhere in this disclosure. For example, the one or more processors 110 included in the controller 108 may receive one or more images of the embedded volumetric field of view 104 from the detector 124 and generate one or more metrology measurements regarding the specimen 106 based on the one or more images received from the detector 124.

[0033] FIG. 1B is a conceptual diagram of an image-based metrology subsystem 102 in an interferometric configuration that can be used to generate volumetric data of a specimen 106, according to one or more embodiments of the present disclosure.

[0034] In at least certain embodiments, as illustrated in FIG. 1B, the interferometer has a measurement arm 146 associated with the sample 106 and a reference arm 148 associated with a reference sample 144, which is used as a reference during interference-based interferometry measurements of the sample 106.

[0035] In some embodiments, volumetric data generation can be performed in various ways, such as by scanning the specimen 106 along a depth direction. For example, in some embodiments, scanning the specimen 106 can be performed by moving the specimen 106 along a depth direction using a translation stage 140, by moving the reference specimen 144 using a reference translation stage (not shown) configured to move the reference specimen 144, by adjusting the phase of the reference beam 166 in the reference arm 148, and / or the like.

[0036] In one embodiment, the metrology subsystem 102 includes at least one detector 124 configured to capture at least a portion of the detectable light 122 from the light collection path 120. As used herein, detectable light 122 can include portions of illumination directed toward the detector 124, such as portions of the illumination beam 116 or portions of any other illumination from any other illumination source. For example, the detectable light 122 can include a measurement beam 168 emanating from the sample 106 and a reference beam 166 emanating from the reference sample 144. The detectable light 122 can also include interference between the measurement beam 168 and the reference beam 166. Such interference can be imaged by the detector 124 to typically generate an interferogram, and, in at least certain embodiments of the present disclosure, to generate volumetric data.

[0037] In some embodiments, the metrology subsystem 102 includes an illumination source 114 configured to generate an illumination beam 116. In embodiments, one or more components (e.g., illumination lens 126) are provided on an illumination path 118 (e.g., illumination subsystem) within the metrology system 100 to direct the illumination beam 116 toward the specimen 106.

[0038] Additionally, in some embodiments, one or more components are provided in the light collection path 120 (e.g., imaging subsystem) within the metrology subsystem 102 to collect light from the specimen 106. It is noted that the terms "illumination," "light," "beam," "illumination beam," etc., are interchangeable as used throughout this disclosure.

[0039] In one embodiment, metrology subsystem 102 includes reference objective 142 configured to receive a portion of illumination beam 116 through beam splitter 136, direct that portion of illumination beam 116 to reference specimen 144, and collect light reflected from reference specimen 144 (e.g., such reflected light may be referred to as a “reference beam 166” of reference arm 148). In this case, measurement objective 134 and specimen 106 may form measurement arm 146 of a Linnik interferometer, and reference objective 142 and reference specimen 144 may form reference arm 148 of the Linnik interferometer, such that interference between measurement beam 168 from measurement arm 146 and reference beam 166 from reference arm 148 may be imaged by detector 124.

[0040] The disclosed systems and methods may be broadly applicable to a wide variety of specimens, where the illumination beam 116 may have any specified spectrum based on the composition of the specimen 106 .

[0041] The illumination beam 116 provided by the illumination source 114 can have any specified wavelength or wavelength range. As contemplated herein, the spectrum of the illumination beam 116 can be selected to transmit through at least a portion of the specimen 106 and reach the embedded volumetric field of view 104 with minimal absorption, or at least acceptable absorption. For example, if the specimen 106 is formed as two bonded semiconductor substrates, the spectrum of the illumination beam 116 can be selected to include wavelengths in the infrared spectral range. For example, a Linnik interferometer can be adapted for infrared imaging. Also, for example, if the specimen 106 is formed as two bonded semiconductor substrates, the spectrum of the illumination beam 116 can be selected to include wavelengths in the short-wave infrared spectral range.

[0042] Also for example, when the volumetric field of view 104 of the specimen 106 to be imaged is the temporary bonding surface 160 of the specimen 106 (i.e., not embedded), the spectrum of the illumination beam 116 can be selected to include wavelengths in the visible spectral range. For example, in some embodiments, a Linnik interferometer configured for operation in the visible spectral range can be used as the metrology subsystem 102.

[0043] In some embodiments, the metrology subsystem 102 is configured to generate images at multiple wavelengths (e.g., illumination spectral ranges, channels, etc.), thereby constituting a multi-wavelength (MWL) metrology subsystem 102. For example, the illumination beam 116 may include different illumination spectral ranges (i.e., channels), and the beam splitter 136 may be a wavelength filtering beam splitter, thereby splitting the illumination beam 116 into two beams with different illumination spectral ranges. However, in this context, "different" may also mean "partially different." For example, at least certain embodiments require that the first and second spectral ranges of light overlap at least somewhat for proper function. Thus, in some embodiments, the first spectral range of light partially overlaps with the second spectral range of light. Such MWL-type configurations / techniques may provide improvements in the quality of the volumetric data (e.g., improved spatial resolution, improved signal-to-noise ratio (SNR), etc.). For example, the illumination spectral range in illumination beam 116 can overlap with a second illumination spectral range, thereby configuring metrology subsystem 102 as a multi-wavelength (MWL) metrology subsystem 102. Additionally, a beam splitter (e.g., beam splitter 136) can include a wavelength filtering beam splitter, allowing reference beam 166 to include illumination in a first spectral range and measurement beam 168 to include illumination in a second spectral range.

[0044] In some embodiments, illumination path 118 includes one or more illumination lenses 126 that direct illumination beam 116 from illumination source 114 toward specimen 106. Additionally, illumination lenses 126 can be arranged to relay one or more field or pupil planes to various locations on illumination path 118. Illumination path 118 can further include one or more illumination control elements 128 suitable for modifying and / or controlling illumination beam 116. Illumination control elements 128 can be, but are not required to be, located at a field plane and / or pupil plane on illumination path 118. For example, the one or more illumination adjustment elements 128 may include, but are not limited to, an illumination aperture stop, an illumination field stop, one or more polarizers, one or more compensators, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, one or more mirrors, one or more lenses, and / or one or more masks.

[0045] For example, in certain embodiments, one or more masks or other elements can be configured to selectively block portions of the illumination beam 116, thereby creating an annular (i.e., ring-shaped) cross-sectional intensity profile at the pupil plane of the illumination path 118, thereby forming the illumination beam 116 as an annular illumination beam. Such an annular illumination beam can generate one or more annular measurement beam rings from one or more diffraction orders emerging from the specimen 106. One or more similar masks and / or other elements can also be used to generate similar and / or matching annular profiles for the reference beam 166. It is noted that, in some embodiments, the annular illumination beam 116 dramatically improves / increases the SNR of the measurement beam 168 compared to using a circular illumination beam. Furthermore, the annular illumination beam 116 can selectively block / reduce unwanted specular reflections from the top (e.g., back) surface of an overlying specimen (e.g., the first specimen 106a in FIG. 1E ), further improving the SNR of the measurement beam 168 compared to using a circular illumination beam. Such improvements may be critical in the context of imaging. It should be noted that, according to certain embodiments, the size of the inner (i.e., inner ring diameter) and outer (i.e., outer ring diameter) diameters of the annular illumination beam 116 may correspond to a maximum numerical aperture (NAmax) and a minimum numerical aperture (NAmin), respectively, and may be optimized for volumetric data generation. For example, simulated derived data and / or real pupil plane image data spanning a range of NAmax and NAmin may be generated at multiple focal planes along the depth direction and used to determine / optimize NAmax and NAmin for volumetric data generation. As an example, NAmax and NAmin may be selected to maximize SNR (e.g., reduce specular reflections) for volumetric data generation in a particular application.

[0046] According to one embodiment, the annular profile of the annular illumination beam 116 can be configured to be shifted across the pupil plane (e.g., by the action of the measurement objective lens 134 and / or other components not necessarily shown), thereby changing the direction in which the illumination is provided.

[0047] According to certain embodiments, the measurement beam 168 can be decentered (e.g., angled) so that the measurement beam 168 is angled (i.e., non-parallel) with respect to the depth direction (e.g., Z direction) of the sample 106. For example, one or more fixed and / or adjustable lenses, reflectors, etc. can be used to set the angle of the measurement beam 168 so that the measurement beam 168 is tilted with respect to the sample 106. Furthermore, such a configuration can be operated so that the coherence gate of the measurement beam 168 is aligned with the focal planes and thus scans the depth direction through the multiple focal planes. Additionally, such tilted / angled configurations can provide improvements, including, but not limited to, more information (e.g., angled volumetric data) and / or a higher SNR. For example, feature / line sidewall surfaces that are parallel to the depth direction are generally easier to image at an angle than directly above.

[0048] In some embodiments, the light collection path 120 includes one or more collection lenses 130 that direct the detectable light 122 from the sample 106 toward the detector 124. In some embodiments, the light collection path 120 also includes one or more collection-adjustment elements 132 suitable for modifying and / or adjusting the detectable light 122. For example, the one or more collection-adjustment elements 132 may include, but are not limited to, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more apodizers, and one or more beam shapers.

[0049] In some embodiments, the metrology subsystem 102 includes a metrology objective 134 that directs the illumination beam 116 toward the sample 106 and / or captures the measurement beam 168 from the sample 106. For example, as depicted in FIG. 1B , the metrology subsystem 102 can include a beam splitter 136 common to both the illumination path 118 and the collection path 120, allowing the metrology objective 134 to simultaneously direct the illumination beam 116 toward the sample 106 and capture the measurement beam 168 from the sample 106. In other embodiments, not shown, the illumination path 118 and the collection path 120 can include separate lenses that direct the illumination beam 116 toward the sample 106 and collect the measurement beam 168, respectively.

[0050] In some embodiments, the cross-sectional area of the illumination beam 116 directed toward the specimen 106 (when looking toward the focal plane) is larger than the field of view of the detector 124. Similarly, in some embodiments, the image area of the multiple images is larger than the cross-sectional area of the volumetric field of view 104. In such cases, the volumetric field of view 104 can be entirely contained within the cross-sectional area of the measurement beam 168 directed toward the specimen 106, and the volumetric field of view 104 is, in a sense, fully illuminated.

[0051] In some embodiments, the detector 124 is a multi-pixel detector (e.g., a camera, a 2D detector, a complementary metal-oxide semiconductor (CMOS), etc.). This allows the detector 124 to image multiple pixels at once, thus more efficiently imaging a volumetric field / area and generating volumetric data. In some embodiments, the detector 124 may be suitable for capturing images of a stationary or moving specimen 106. For example, the detector 124 may include, but is not limited to, a photodiode array (PDA), a charge-coupled device (CCD), a CMOS device, a time-delay integration (TDI) detector, a line-scan detector, a photomultiplier tube (PMT), an avalanche photodiode (APD), etc. In some embodiments, the detector 124 may comprise a spectroscopic detector suitable for identifying wavelengths of radiation emanating from the specimen 106 and dispersed onto a sensor using a dispersive element.

[0052] In some embodiments, the specimen positioning subsystem 138 is used to acquire multiple images of a volumetric field of view of the specimen 106 at different focal planes along the depth (eg, Z direction) of the specimen.

[0053] In one embodiment, the specimen positioning subsystem 138 in the metrology subsystem 102 is configured to adjust the specimen 106 and / or the illumination beam 116 before, during, and / or after measurement. For example, the specimen positioning subsystem 138 depicted in FIG. 1B includes a translation stage 140 that can adjust the position of the specimen 106 along any dimension, including, but not limited to, lateral position in the XY plane, axial position along the Z axis (e.g., the optical axis of the metrology objective 134), tip, tilt, etc. According to another example, although not shown, the specimen positioning subsystem 138 can include one or more scanning optics (e.g., galvanometers, rotatable mirrors, etc.) suitable for scanning the illumination beam 116 across the specimen 106 or a portion thereof. Similarly, in some embodiments, a reference translation stage (not shown) within the metrology subsystem 102 is configured to adjust the reference specimen 144 (as shown in FIG. 1C ) and / or the reference beam 166 (as directed at the reference specimen 144) before, during, and / or after measurement. Focusing capabilities can be incorporated within the specimen positioning subsystem 138 of embodiments, and can be achieved by a photodiode or other components, as described below in connection with FIG. 1C .

[0054] 1C is a schematic diagram of a metrology subsystem 102 having a Linnik interferometer-based specimen positioning subsystem 138 in accordance with one or more embodiments of the present disclosure. Note that in at least certain embodiments, FIG. 1C includes components (e.g., photodiode 150, second illumination source 114′) that facilitate focusing using specimen positioning data. The specimen positioning data can be used to bring the specimen 106 into focus.

[0055] In certain embodiments, one or more components within the specimen positioning subsystem 138 detect and / or monitor the location of the specimen 106, the volumetric field 104, the surface 160, or any designated layer within the specimen 106 along the optical axis of the measurement objective 134. In this manner, the specimen positioning subsystem 138 can precisely align the volumetric field 104 within the metrology subsystem 102. As contemplated herein, precise alignment of the volumetric field 104 within the metrology system 100 can provide numerous benefits. For example, precise alignment of the volumetric field 104 can facilitate precise control of the spatial and angular profile of the illumination beam 116 from the illumination source 114 over the volumetric field 104 through the use of customized illumination field and / or pupil stops, as discussed throughout this disclosure. According to another example, precise alignment of the volumetric field 104 can facilitate precise alignment of the volumetric field 104 with respect to the detector 124 to provide a high quality image of a specified plane (e.g., a field plane or a pupil plane).

[0056] Various techniques can be used by the specimen positioning subsystem 138 to detect and / or monitor the axial location of the specimen 106, or any portion thereof. In one embodiment, the specimen positioning subsystem 138 includes a Linnik interferometer for determining and / or monitoring the position of the volumetric field of view 104 along the optical axis of the metrology objective 134. For example, the Linnik interferometer can be configured to operate with the spectrum of the illumination beam 116 from the illumination source 114, and although not required, the illumination source 114 can be narrowband (e.g., having a bandwidth of about 5 nm or less). For example, the metrology subsystem 102 or a component interferometer thereof can include a photodiode 150 configured to be focused, in use, onto the interferometer's detector 124.

[0057] In some embodiments, the metrology subsystem 102 includes a modulator 158 configured to modulate the photodiode beam (i.e., light directed toward the photodiode 150) (e.g., the photodiode beam may include a secondary illumination beam from the second illumination source 114′). For example, the modulator 158 may include at least one of a binary phase filter (BPF), a full width at half maximum (FWHM) filter, and an annular mask. In another example, the modulator 158 includes a BPF, a FWHM filter, and an annular mask. For example, the modulator 158 may be configured for a 5 nm bandwidth.

[0058] The depth direction may be defined as the Z direction in FIG. 1C, perpendicular to the top surface of the specimen, substantially perpendicular (e.g., within 20 degrees) to the top surface of the specimen, etc. Similarly, the plane of focus may be perpendicular to the Z direction in FIG. 1C, perpendicular to the depth direction, parallel to the top surface of the specimen, substantially parallel to the top surface of the specimen, etc.

[0059] In one embodiment, metrology subsystem 102 includes a photodiode 150 that generates specimen positioning data in the form of an interference pattern related to the interference between measurement beam 168 in measurement arm 146 and reference beam 166 in reference arm 148 of the Linnik interferometer. In one embodiment, metrology subsystem 102 includes an additional beam splitter 152, as depicted in FIG. 1C , that provides a continuous interference image. Also, in one embodiment, metrology subsystem 102 includes a translatable mirror (e.g., a flip mirror, a mirror on translation stage 140, etc.) that can selectively direct light to photodiode 150 for use in generating the interference image. For example, the metrology subsystem 102 can direct all of the light from the beam splitter 136 to the photodiode 150 while adjusting the position of the specimen 106 before measurement to maximize the signal available for focus detection, and then during measurement, direct all of the light from the beam splitter 136 to the detector 124 for metrology measurements (e.g., capturing one or more specimen images).

[0060] According to some embodiments, a shutter 172 or other beam deflector may be provided in the metrology subsystem 102 to selectively block light in the reference arm 148 during metrology measurements. For example, the metrology subsystem 102 may be (or include) a bright-field subsystem. As an example, the metrology subsystem 102 may be configured for multi-mode imaging using other imaging modes (e.g., Linnik interferometry mode) in addition to bright-field imaging techniques.

[0061] It is contemplated herein that illumination requirements for metrology and specimen positioning may be different. Accordingly, any combination of illumination sources and optical elements may be provided within the metrology subsystem 102 to provide light with characteristics selected to suit both metrology and specimen positioning measurements. For example, the metrology subsystem 102 may include a beam diffuser or other suitable component to reduce the spatial coherence of the light used for specimen positioning, thereby reducing speckle during measurements.

[0062] 1C, the metrology subsystem 102 includes a common illumination source 114 for both volumetric data generation and specimen positioning. Within the metrology subsystem 102, one or more optical elements, such as, but not limited to, a spectral filter, a spatial filter, a speckle reducer (e.g., a diffuser), a field stop, a pupil stop, a polarizer, etc., may be included to modify the characteristics of the illumination beam 116 from the common illumination source 114 for specimen positioning measurements. The optical elements may be located in any suitable location, including, but not limited to, an illumination path 118 to modify the light incident on the specimen 106 and / or a collection path 120 to modify the light collected from the specimen 106.

[0063] For example, FIG. 1C depicts a spectral filter 154 in the collection path 120 that can modify the spectrum of the illumination beam 116 incident on the photodiode 150 during specimen positioning measurements. For example, the spectral filter 154 can narrow the bandwidth of the illumination beam 116 used for specimen positioning measurements to a specified bandwidth, such as, but not limited to, 10 nm, 5 nm, 2 nm, 1 nm, or any specified bandwidth. In this manner, the illumination beam 116 used during specimen positioning measurements can be monochromatic or quasi-monochromatic. It should be understood that while the arrangement depicted in FIG. 1C depicts the spectral filter 154 prior to the photodiode 150, it should be understood that the spectral filter 154 can be located in any suitable location, including, but not limited to, in the illumination path 118.

[0064] While spectral filter 154 can aid in focusing, in at least certain embodiments, the spectral filter can also be important with respect to the imaging itself. By way of example, and without any positioning constraints, a spectral filter may be placed in the collection path prior to lens 130, as illustrated by spectral filter 170. Spectral filter 170 may have the same, similar, or distinct characteristics as spectral filter 154. For example, spectral filter 170 may be a narrow-band spectral filter. It should be noted that in at least certain embodiments, without the use of narrow-band spectral filter 170 placed prior to lens 130, the contrast (e.g., SNR) of the images produced would be quite poor, and thus the axial resolution of such images would be poor.

[0065] In another embodiment, the metrology subsystem 102 includes a separate illumination source 114' for specimen positioning. It should be noted that the combined use of separate illumination sources 114' and photodiodes 150 for specimen positioning is generally disclosed in U.S. Patent Application No. 17 / 069,177.

[0066] For example, as depicted in FIGURE 1C, a separate illumination source 114' for specimen positioning can be integrated into the specimen positioning subsystem 138. As an example, the specimen positioning subsystem 138 can utilize an additional beam splitter 152, depicted in FIGURE 1C, to direct light from the separate illumination source 114' toward the specimen 106. Alternatively, although not shown, a beam splitter 136 or other beam selector can be provided in the illumination path 118 to allow selective illumination of the specimen 106 from one of two or more illumination sources. In general, a beam splitter can be configured to split illumination into two or more illumination paths to travel in two or more directions.

[0067] As further contemplated herein, the geometry of the embedded volumetric field 104 at the specimen 106 can present challenges to typical interferometric specimen positioning techniques, including but not limited to Linnik interferometry. For example, chromatic dispersion and spherical aberration can be introduced during light propagation through the specimen 106 and reference specimen 144, which can adversely affect specimen positioning measurements.

[0068] The metrology subsystem 102 can utilize any spatial or angular profile of light for specimen positioning measurements. In some embodiments, the metrology subsystem 102 provides oblique illumination (e.g., annular, dipole, quadrupole, etc.) for specimen positioning measurements. For example, although not required, the metrology subsystem 102 can provide a central obscuration (e.g., a numerical aperture) in the illumination pupil of the illumination path 118 to provide annular illumination over a specified range of angles relative to the specimen 106 and reference specimen 144.

[0069] The metrology subsystem 102 may include various other components (e.g., lenses, optics, etc.) for directing / shaping the illumination, such as, but not limited to, components 162a, 162b, 162c, and 162d shown in various locations.

[0070] Figure 1D is a schematic ray diagram illustrating oblique illumination propagation within metrology subsystem 102, according to one or more embodiments of the present disclosure. For example, Figure 1D can depict the propagation of illumination beam 116 from a single point along an annular profile. It should further be understood that Figure 1D is not intended to be a strict ray diagram, and the depiction of the three rays after pupil plane 156 is provided solely for illustrative purposes to show illumination beam 116 of specimen 106 and reference specimen 144 across a spatial field.

[0071] As contemplated herein, oblique illumination, particularly illumination at a large angle or with a high numerical aperture (NA), can facilitate sensitive and accurate specimen positioning measurements using Linnik interferometry. For example, reflections from the top surface of the specimen 106 and from the top surface of the reference specimen 144 can affect the signal associated with reflections from the volumetric specimen field 104 embedded within the specimen 106. This can be mitigated by designing the illumination beam 116 to exhibit an annular or other high NA profile during specimen positioning measurements, thereby avoiding collection of specular reflections from the top surfaces of the specimen 106 and reference specimen 144.

[0072] At least certain embodiments of metrology system 100 may be used in a wide range of applications, some non-limiting examples of which are illustrated in Figures 1E-1H. For example, applications may include generating volumetric data for inter-specimen voids, pad geometry, through silicon vias, targets, etc.

[0073] 1E is a schematic diagram of a metrology subsystem 102 including a metrology objective 134 imaging a void 104 in bonded specimens 106a, 106b, according to one or more embodiments of the present disclosure, with other components of the metrology subsystem 102 cut away for simplicity and clarity.

[0074] In various embodiments, as discussed elsewhere, a void 104 may form at the interface between two bonded specimens 106a and 106b. Note that specimen 106 generally may have multiple layers 164 (e.g., two layers, ten layers, hundreds of layers, etc.). The surface 160 of specimen 106 may be directly and / or indirectly mirrored. An illumination beam 116 is shown passing through the first specimen 106a to image the void 104.

[0075] As noted above, when imaging the embedded volumetric field 104, it may be advantageous to use a metrology subsystem 102 configured to image in the infrared and / or shortwave infrared spectral range of light, as such light provides excellent imaging of the embedded portion of the specimen 106.

[0076] 1F is a schematic diagram of a metrology subsystem 102 having a metrology objective 134 imaging the topography of a surface 160 (e.g., a concave shape of a pad surface) of a temporarily bonded specimen 106, according to one or more embodiments of the present disclosure. While shown in a flat configuration, it is noted that the topography of surface 160 may be concave relative to the metrology subsystem 102.

[0077] As noted above, when imaging the surface of a specimen rather than an embedded volumetric field, penetration through the specimen may not be important, and it may be advantageous to use a metrology subsystem 102 configured to image in any optical spectral range that meets other requirements. For example, the metrology subsystem 102 may be configured to image the surface of the specimen 106 in the visible light spectral range or some other spectral range.

[0078] 1G is a schematic diagram of the metrology subsystem 102, including the metrology objective 134, imaging through-silicon vias (TSVs) of bonded specimens 106a, 106b, and 106c, where the TSVs are assumed to fall within the volumetric field of view 104, in accordance with one or more embodiments of the present disclosure. A TSV can be defined as a vertical electrical connection (via) that extends completely through a silicon wafer or die.

[0079] 1H is a schematic diagram of a metrology subsystem 102 having a measurement objective 134 imaging a target on a specimen 106, in accordance with one or more embodiments of the present disclosure, where the target falls within the volumetric field of view 104. For example, the target may be, but is not limited to, a target grating (e.g., an AIM target) located within a scribe line on a wafer. For example, the target may be an overlay target.

[0080] FIG. 2 illustrates a 3D volumetric topology profile 200 of an embedded volumetric field 104 of a specimen 106, reconstructed from interferometry tool data (e.g., interferogram data, multiple interferogram data, data obtained using an interferogram of the present disclosure, volumetric data, and / or the like) in accordance with one or more embodiments of the present disclosure. Note that the topology profile 200 is shown for illustrative purposes as an Advanced Imaging Metrology (AIM) metrology target; other portions / elements / areas may be imaged to obtain volumetric data, such as, but not limited to, voids 104 at an interface and / or the surface of a pad after temporary bonding. For example, volumetric data obtainable using embodiments of the present disclosure may be depicted similarly to the volumetric data depicted in FIG. 2. That is, the topology profile 200 depicted may represent, but is not limited to, resolution, roughness / variability, and / or three-dimensional details obtainable from at least one embodiment of the present disclosure.

[0081] 3 is a flow diagram depicting steps performed in a method 300 according to one or more embodiments of the present disclosure. For example, the controller 108 may be configured to be communicatively coupled to the metering subsystem 102 of the metering system 100 and include a processor 110 configured to execute program instructions that cause the one or more processors 110 to perform the steps of the method 300 (and any steps, methods, etc. of the present disclosure).

[0082] In step 302, the specimen 106 is scanned at multiple focal planes located along the depth of the specimen 106, and the detector 124 of the metrology subsystem 102 generates multiple images of the volumetric field of view 104 at the multiple focal planes.

[0083] For example, in some embodiments, such scanning of the specimen 106 can be achieved by moving the specimen 106 in the Z / depth direction using a translation stage 140, moving the reference specimen 144 using a reference translation stage (not shown), adjusting the phase of the reference beam 166 in the reference arm 148, and / or the like.

[0084] In step 304, the multiple images are aggregated to generate volumetric data for the volumetric field of view 104 of the specimen 106, for example, by generating multiple interferogram data sets for multiple locations (e.g., pixels) common to at least some of the multiple images. Further, for example, each interferogram data set can be an interferogram corresponding to each location, and each location can be a pixel. In this way, an interferogram can be generated for each pixel. Volumetric data can be generated based on the multiple interferograms, although this is not required.

[0085] In an optional step, the volumetric data can be used to construct a height map of the embedded volumetric field 104 or post-cementation surface 160 of the specimen 106 .

[0086] In an optional step, the volumetric data can be used to construct volumetric profiles that show the various elements in 3D volume.

[0087] In an optional step, one or more voids 104 are identified based on the volumetric data.

[0088] In an optional step, characteristics of one or more voids 104 are determined based on the volumetric data, such as size, thickness, volume, area, width, length, roughness, location, category, and / or some other characteristic. Examples of categories include nuisance and killer.

[0089] The metrology system 100 may include or be coupled to a review tool and / or a PWG tool. A PWG tool may be an imaging tool configured to image all (i.e., the entire) of the specimen 106 at once (e.g., an interferometry-based tool, but with a significantly larger field of view to image the entire wafer). A review tool may be, for example, an acoustic microscope.

[0090] In an optional step, points of interest on (and / or embedded within) the specimen 106 are identified using a review tool and / or PWG tool. For example, at least some of the embedded volumetric fields 104 may be located at the points of interest. However, not all points of interest necessarily result in problems, and thus, like false positives, they may simply be flagged areas for further review. These points of interest can be identified using such tools (e.g., review tool, PWG tool) because they image anomalies or potential anomalies. Potential anomalies include any measurement results that are unexpected, unexpected, and / or above a threshold. For example, potential anomalies include outliers, height discontinuities, etc. on the image that may be particles / voids / defects. Such tools may have lower resolution than the metrology subsystem 102 described elsewhere in this disclosure, and may be required to flag such anomalies at such points of interest for further review.

[0091] The step of scanning the specimen 106 and / or receiving multiple images (i.e., step 302) may take into account (e.g., be notified of) the points of interest. For example, the step of receiving multiple images may take into account the points of interest. As an example, the points of interest may be in some way within the volumetric field of view 104 of the specimen 106 under scrutiny.

[0092] In an optional step, a set of candidate volumetric fields is determined. For example, candidate volumetric fields (e.g., candidates) can be areas of the specimen 106 that are candidates for overlay metrology by design. For example, candidate metrology / misalignment targets on one or more layers of the specimen can be candidate metrology targets, such as box-in-box (BiB) metrology targets, AIM metrology targets, etc.

[0093] In one example, a narrowed set of candidate volumetric views is generated by removing some candidate volumetric views from the set of candidate volumetric views based on the volumetric data. For example, when the volumetric data is used to identify voids that overlap with a candidate volumetric view, the overlay target associated with the candidate volumetric view can be excluded from measurement in the overlay metrology process. This can improve efficiency by skipping less useful measurement results.

[0094] In one example, an overlay metric is performed based on the candidate volumetric view refinement set.

[0095] In an optional step, the overlay metrology recipe is improved by generating performance indicators (e.g., key performance indicators (KPIs)) configured to correlate one or more voids 104 with one or more overlay metrology results. For example, some voids 104 may be correlated with poor / misaligned overlay metrology results on the metrology target, while other voids 104 may not appear to have any effect / correlation on overlay. For example, the KPIs may be normalized values (e.g., values between 0.00 and 1.00) that represent the likelihood that a void 104 characteristic (e.g., size, shape, location, etc.) can be used to predict overlay. For example, a high KPI value may indicate that a large void is associated with (or may be the cause of) a large overlay in a monolithic bond specimen.

[0096] 4 is a flow diagram depicting steps performed in a volumetric data generation method 400 in accordance with one or more embodiments of the present disclosure. For example, the controller 108 may be configured to be communicatively coupled to the metrology subsystem 102 of the metrology system 100 and include a processor 110 configured to execute program instructions that cause the one or more processors 110 to perform the steps of the method 400.

[0097] Step 402 identifies points of interest across the exemplar 106. In certain embodiments, this point of interest identification is performed based on one or more sources 410 (e.g., sources 410a, 410b, 410c, 410d).

[0098] For example, points of interest may be based on user sources 410a. In one example, a user (e.g., a process engineer) may determine whether one or more points on the specimen should be examined based on other sources, such as scanning electron microscope (SEM) images, specimen design, or some other source, and identify those points as points of interest.

[0099] In another example, the points of interest may be based on PWG tool measurement results 410b. For example, the PWG tool may be pre-configured to rely on algorithms, programs, etc. to identify points of interest, allowing the user to directly identify such points of interest based on their own judgment with little or no user input.

[0100] In another example, the points of interest may be based on acoustic microscopy tool measurements 410c. For example, the acoustic microscopy tool may be pre-configured to rely on algorithms, programs, etc. to identify points of interest, allowing for direct identification of such points of interest based on the user's own judgment with little or no user input.

[0101] Alternatively, the focus may be based on some other data 410d that may be used for such purposes.

[0102] In step 404, volumetric data of the specimen 106 is generated at the points of interest. For example, such volumetric data can be generated using any of the steps of this disclosure (e.g., steps 302 and 304).

[0103] In some embodiments, step 406 and / or step 408 occurs.

[0104] In step 406, the specimen manufacturing process is monitored based on the volumetric data. For example, the volumetric data can be monitored to detect breaches beyond a threshold. For example, the volumetric data can be volumetric profiles of overlay targets (e.g., grating targets), with each volumetric data representing an overlay metrology result. For example, the volumetric profile of the overlay target can be taken into account when determining the overlay metrology result. For example, the location of the overlay target relative to an anchor fiducial (e.g., the edge of the die) or relative to another overlay target located below the specimen 106 can be used to determine the overlay metrology result based on the volumetric data. Furthermore, multiple overlay metrology results can be taken across a single specimen, multiple specimens, multiple specimen lots, etc., and used to generally monitor the overlay of the specimen manufacturing process. A predetermined threshold can be determined based on acceptable overlay metrology, and an alert can be sent to a user if the threshold is violated.

[0105] In step 408, the specimen manufacturing process is adjusted based on the volumetric data. For example, one or more tools of the manufacturing process may be adjusted (e.g., recalibrated, realigned) if a threshold is violated. For example, the adjustment may also be of some other kind, such as adjusting the film thickness of the specimen 106.

[0106] Referring again to Figures 1B and 1C, additional details of various component embodiments will be described.

[0107] Detectable light 122 may include any type of radiation emanating from sample 106 and / or reference sample 144. For example, detectable light 122 may include light or particles. For example, in some embodiments, detectable light 122 includes measurement beam 168 and / or reference beam 166. For example, detectable light 122 may include portions of illumination beam 116 that are reflected and / or scattered by sample 106, which may be referred to as measurement beam 168 or portions thereof. For example, detectable light 122 may include luminescence induced by absorption of illumination beam 116 by sample 106. For example, detectable light 122 may include particles resulting from sample 106 in response to illumination beam 116, such as, but not limited to, backscattered electrons and secondary electrons.

[0108] Multiple detectors 124 may be provided within the metrology system 100 in association with multiple beam paths generated by the one or more beam splitters 136, allowing multiple metrology measurements to be facilitated by the metrology system 100. Additionally, in some embodiments, the detectors 124 may comprise spectroscopic detectors suitable for distinguishing between wavelengths of radiation emanating from the sample 106.

[0109] The detector 124 may also be located at any imaging plane of the metrology system 100. For example, the detector 124 may be located at a plane conjugate to the specimen 106 to generate an image of the specimen 106. For example, the detector 124 may be located at a pupil plane (or a conjugate thereof) to generate a pupil image.

[0110] In some embodiments, the metrology subsystem 102 also includes a detector 124 configured to capture light emanating from the sample 106 via the light collection path 120. For example, the detector 124 may receive radiation reflected or scattered from the sample 106 (e.g., by specular reflection, diffuse reflection, etc.). For example, the detector 124 may receive radiation generated by the sample 106 (e.g., luminescence associated with absorption of the illumination beam 116). For example, the detector 124 may receive one or more diffraction orders of radiation from the sample 106 (e.g., zeroth diffraction order, ±1st diffraction orders, ±2nd diffraction orders, etc.).

[0111] Additionally, according to some embodiments, multiple detectors 124 may be provided within the metrology subsystem 102 to facilitate multiple metrology measurements performed by the metrology subsystem 102. In this manner, multiple coincidence measurements may be performed with the metrology subsystem 102 depicted in FIG.

[0112] Illumination source 114 may also provide light having some specified temporal characteristics. In some embodiments, illumination source 114 includes one or more continuous wave light sources that provide a continuous wave illumination beam 116. In some embodiments, illumination source 114 includes one or more pulsed light sources that provide a pulsed or otherwise modulated illumination beam 116. For example, illumination source 114 may include one or more mode-locked lasers, one or more Q-switched lasers, etc.

[0113] While illumination source 114 can include any type of light source known in the art, it should be noted that for interferometric measurements, measurement beam 168 is generally coherent (as opposed to incoherent, out-of-phase, etc.). For example, in some embodiments, illumination source 114 includes one or more coherent light sources, such as, but not limited to, one or more laser light sources. In such cases, illumination source 114 can generate illumination beam 116 with high coherence (e.g., high spatial and / or temporal coherence). For example, illumination source 114 can include one or more broadband lasers, such as, but not limited to, one or more supercontinuum (ultra-broadband) lasers or white light lasers. For example, illumination source 114 can include one or more narrowband lasers. For further example, illumination source 114 can include one or more tunable lasers to tune the spectral intensity of resulting illumination beam 116. Furthermore, the coherent illumination source 114 may be based on any type of technology or product design, for example, the illumination source 114 may include any combination of, but not limited to, one or more fiber lasers, one or more diode lasers, and one or more gas lasers.

[0114] Metrology system 100 is generally versatile, and for at least that reason, it can also be configured to use incoherent illumination to obtain noninterferometric measurements. For example, in the same embodiment as described above, illumination source 114 can include one or more low-coherence light sources, resulting in illumination beam 116 with low or partial coherence (e.g., low spatial and / or temporal coherence). For example, illumination source 114 can include one or more light-emitting diodes (LEDs) or superluminescent LEDs. For example, illumination source 114 can include a laser-sustained plasma (LSP) light source, such as, but not limited to, an LSP lamp, LSP bulb, or LSP chamber suitable for containing one or more elements capable of emitting broadband illumination when excited into a plasma state by a laser light source. For example, illumination source 114 can include a lamp light source, such as, but not limited to, an arc lamp, a discharge lamp, an electrodeless lamp, or the like. Additionally, illumination source 114 may include any combination of light sources. In one embodiment, illumination source 114 includes one or more supercontinuum laser sources that provide broadband illumination and one or more partially coherent high-brightness LEDs that fill gaps in the spectrum of the one or more supercontinuum laser sources.

[0115] Reference specimen 144 may include any specimen suitable for providing a reference beam within the Linnik interferometer. For example, reference specimen 144 may be designed to at least partially replicate specimen 106. This allows the Linnik interferometer to be balanced so that the optical properties of the beam propagating through reference specimen 144 are the same as or substantially similar to those of the beam propagating through specimen 106.

[0116] In some embodiments, the reference specimen 144 can be formed from two or more bonded substrates having the same or similar refractive index as the specimen 106 (e.g., according to a metrology recipe / method). The substrates (e.g., substrates 106a, 106b, 106c) can be of different thicknesses. Furthermore, the reference specimen 144 can be formed, although not required, with a reflective layer or coating (e.g., metal coating, etc.) at the interface between the two bonded substrates to enhance the reflectivity of the interface. Also, in some embodiments, if the specimen 106 has one or more intermediate layers that are adjacent to or form the embedded volumetric field 104, the reference specimen 144 can have the same or similar layers. The intermediate layers can be formed as a multi-layer wafer, with each layer etched to a specific, potentially separate, thickness.

[0117] In some embodiments, the reference specimen 144 is formed as a single substrate, with its underside forming the reference surface. Furthermore, the reference surface may, but need not, include a reflective layer or coating (e.g., a metal coating, etc.) to enhance the reflectivity of the reference surface. It should be understood that the reference specimen 144, or any portion thereof, may have any specified thickness, depending on the application and characteristics of the specimen 106. For example, if the specimen 106 is formed from one or more bonded semiconductor wafers, the reference specimen 144 may be formed from one or more semiconductor wafers having the same thickness as the top wafer 106a of the specimen 106 (e.g., 775 μm, 750 μm, 600 μm, 300 μm, 100 μm, etc.). However, this example is not limiting, and the reference specimen 144 may have a different thickness than the top wafer 106a of the specimen 106.

[0118] In one embodiment, when generating volumetric data for the embedded volumetric field 104 (e.g., inter-specimen voids or TSVs), the thickness of the reference specimen 144 is matched to the thickness of the material above (along the depth direction) the embedded volumetric field 104. In this manner, the measurement beam 168 and the reference beam 166 can be configured to pass through material of the same (or similar) thickness. "Similar" can mean, for example, within 5%, 10%, etc.

[0119] Additionally, in some embodiments, the reference specimen 144 may have patterned features in one or more locations (e.g., the backside of a single reference substrate or the interface between bonded substrates) to facilitate alignment of the reference specimen 144.

[0120] It should be noted that phrases such as "according to a weighing recipe," "according to a recipe," "according to a recipe," and the like may mean that the weighing system 100 is configured to align with a recipe, is programmed to align with a recipe, and / or the like. A recipe may be a plan, procedure, method, program instructions, and / or the like. Furthermore, samples and the like do not necessarily have to be part of the weighing system 100 according to a weighing recipe; conversely, the weighing system 100 may be configured to align with and / or for such samples. For example, "according to a weighing recipe" may mean according to what the weighing system 100 and / or program instructions are configured for.

[0121] Referring back to FIG. 1A, additional details of various component embodiments will be described.

[0122] As previously described herein, the controller 108 of the weighing system 100 may include one or more processors 110 and a memory 112. The memory 112 may contain program instructions configured to cause the one or more processors 110 to perform the various steps of the present disclosure.

[0123] Additionally, according to some embodiments, a display of the user interface may be configured to display data from the weighing system 100 to the user.

[0124] As previously described herein, one or more processors 110 included in the controller 108 may be communicatively coupled to a memory 112 and may be configured to execute a set of program instructions stored in the memory 112, which may be configured to cause the one or more processors 110 to perform various functions and steps of the present disclosure.

[0125] One or more components of the metering system 100 may be communicatively coupled to various other components of the metering system 100 in any manner known in the art. For example, one or more processors 110 may be communicatively coupled to each other and to other components via wired connections (e.g., copper wire, fiber optic cable, etc.) or wireless connections (e.g., RF coupling, IR coupling, WiMax®, Bluetooth®, 3G, 4G, 4G LTE, 5G, etc.). Also, for example, the controller 108 may be communicatively coupled to one or more components of the metering system 100 via any wired or wireless connection known in the art.

[0126] According to some embodiments, the one or more processors 110 may include one or more processing elements of any type known in the art. In this sense, the one or more processors 110 may include any microprocessor-based device configured to execute software algorithms and / or instructions. According to some embodiments, the one or more processors 110 may be a desktop computer, mainframe computer system, workstation, image computer, parallel processor, or other computer system (e.g., networked computer) configured to execute programs that cause the weighing system 100 to operate as described elsewhere in this disclosure. It should be appreciated that steps described elsewhere in this disclosure may be performed by a single computer system or, alternatively, by multiple computer systems. It should also be appreciated that steps described elsewhere in this disclosure may be performed on any one or more of the one or more processors 110. In general, the term "processor" may be broadly defined to encompass any device having one or more processing elements that execute program instructions obtained from memory 112. Additionally, various subsystems of metrology system 100 (e.g., metrology subsystem 102, interferometer, controller 108, user interface, etc.) may incorporate processors or logic elements suitable for performing at least a portion of the steps described elsewhere in this disclosure. Accordingly, the above description should be taken as merely illustrative and not as a limitation on the present disclosure.

[0127] The memory 112 may include any storage medium known in the art suitable for storing program instructions executable by the one or more processors 110 in conjunction therewith and data received from the metering system 100. For example, the memory 112 may include a non-transitory storage medium. For example, the memory 112 may include, but is not limited to, ROM, RAM, magnetic or optical memory (e.g., disk), magnetic tape, solid state drives, etc. It is further noted that the memory 112 may be housed within a common controller housing with the one or more processors 110. In an alternative embodiment, the memory 112 may be located remotely from the physical locations of the processors 110, the controller 108, etc. In another embodiment, the program instructions retained by the memory 112 may cause the one or more processors 110 to perform the steps described elsewhere in this disclosure.

[0128] In some embodiments, a user interface is communicatively coupled to the controller 108. The user interface may include, but is not limited to, one or more desktops, tablets, smartphones, smartwatches, etc. In some embodiments, the user interface includes a display that is used to display data from the weighing system 100 to a user. The user interface display may include any display known in the art. For example, the display may include, but is not limited to, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a CRT display, etc. Those skilled in the art should recognize that any display device that can be integrated with a user interface is suitable for implementation in the present disclosure. In some embodiments, the user interface includes a user input device through which a user can input selections and / or commands in response to data displayed to the user.

[0129] All methods described herein may include storing results of one or more steps of a method embodiment in a memory. These results may include any of the results described herein and may be stored in any manner known in the art. The memory may include any of the memories described herein, as well as any other suitable storage medium known in the art. After the results are stored, they may be accessed in the memory and used in any of the method or system embodiments described herein, formatted for display to a user, used in another software module, method, or system, etc. Furthermore, the storage of the results may be "permanent," "semi-permanent," "transient," or for some period of time. For example, the memory may be RAM, and the results may not necessarily reside in the memory permanently.

[0130] It is further contemplated that each of the method embodiments described above can include any other step(s) of any other method(s) described herein. Additionally, each of the method embodiments described above can be performed by any of the systems described herein.

[0131] As those skilled in the art will recognize, the components, acts, devices, objects, and accompanying discussions described herein are used as examples for the sake of conceptual clarity, and various structural modifications are contemplated. Thus, as used herein, the specific exemplars described above and the accompanying discussions are intended to be representative of their more general class. In general, the use of any specific exemplar is intended to be representative of that class, and the non-inclusion of specific components, acts, devices, and objects should not be construed as a limitation.

[0132] Directional terms used herein, such as "top," "bottom," "up," "down," "upward," "upward," "downward," and "downward," are intended to indicate relative positions for descriptive purposes and are not intended to specify an absolute reference frame. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments.

[0133] With respect to the use of substantially all plural and / or singular terms herein, those skilled in the art will be able to translate from the plural to the singular and / or from the singular to the plural as appropriate to the context and / or application. In the interest of clarity, the various singular / plural permutations have not been explicitly set forth herein.

[0134] The subject matter described herein is sometimes depicted as various components embedded within or connected or coupled to other components. It should be understood that such illustrated architectures are merely exemplary, and that in fact, many other configurations that achieve the same functionality can be implemented. Conceptually, any arrangement of components that achieves the same functionality is effectively "integrated" to achieve the desired functionality. Thus, any two components herein that are combined to achieve a particular function can be considered to be "integrated" with each other to achieve the desired functionality, regardless of the architecture or intervening components. Similarly, any two components so integrated can be considered to be "connected" or "coupled" to each other to achieve the desired functionality, and any two components that can be so integrated can be considered to be "combinable" with each other to achieve the desired functionality. Examples of connectable include, but are not limited to, physically interlockable and / or physically interacting elements, and / or wirelessly interlockable and / or wirelessly interacting elements, and / or logically interlockable and / or logically interacting elements.

[0135] The present invention is further defined by the appended claims. Generally, the terms used in this application, particularly in the appended claims (e.g., the body of the appended claims), are generally intended to be "open" (e.g., the term "comprising" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "including" should be interpreted as "including but not limited to," etc.). Those skilled in the art will also understand that if a specific number of claim-introducing features is intended, that intention will be clearly stated in the claim, and the absence of such features indicates no intention. For example, as an aid to understanding, some of the appended claims below incorporate claim-introducing features through the use of the introductory phrases "at least one" and "one or more." However, the use of the indefinite article "a" or "an" to introduce a claim feature should not be interpreted as implying that all individual claims containing that feature are limited to inventions containing only one of that feature, nor should such interpretation be interpreted when the introductory phrase "one or more" or "at least one" coexists with an indefinite article, such as "a" or "an," in the same claim (e.g., "a" and / or "an" should generally be interpreted as meaning "at least one" or "one or more"). The same is true for the introduction of claim features with the use of a definite article. Additionally, even when a specific number of a claim feature is specified, that number should generally be interpreted to mean at least that specified number, as would be recognized by a person skilled in the art (e.g., the bare phrase "two features" without any other modifier generally means at least two features or more than two features).Furthermore, where a convention similar to "at least one of A, B, and C, etc." is used, the syntax is generally intended to conform to the way a person skilled in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include, but is not limited to, a system having only A, only B, only C, both A and B, both A and C, both B and C, and / or a system having all three of A, B, and C, etc.). Where a convention similar to "at least one of A, B, or C, etc." is used, the syntax is generally intended to conform to the way a person skilled in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include, but is not limited to, a system having only A, only B, only C, both A and B, both A and C, both B and C, and / or a system having all three of A, B, and C, etc.). As will also be understood by those skilled in the art, nearly all presentations of two or more alternative terms by disjunctive conjunctions and / or disjunctive phrases, whether appearing in the specification, claims, or drawings, should be understood to contemplate the inclusion of either, either, or both terms. For example, the phrase "A or B" would be understood to encompass the possibilities of "A" or "B" or "A and B."

[0136] The present disclosure and many of its attendant advantages will be understood from the foregoing description, and it will also be apparent that various changes can be made in the form, construction and arrangement of the parts without departing from the disclosed subject matter or diminishing all of its essential advantages. The described form is illustrative only, and it is the intent of the following claims to encompass and embrace all such modifications. It is the appended claims which further define the invention.

Claims

1. 1. A weighing system comprising:

1. A weighing system comprising a weighing subsystem, the weighing subsystem comprising: a detector configured for multi-pixel imaging; an illumination source configured to generate an illumination beam; a beam splitter configured to split the illumination beam into a measurement beam propagating in a measurement arm and a reference beam propagating in a reference arm; a measurement objective configured to direct the measurement beam at a specimen; one or more illumination optics configured to illuminate a volumetric field of the specimen with the measurement beam through the measurement objective; and a reference objective configured to direct the reference beam to a reference sample; the metrology subsystem is configured to image the volumetric field of the specimen onto the detector according to a metrology recipe and relying on interference between the metrology beam and the reference beam; a weighing system comprising a controller communicatively coupled to the detector, the controller having one or more processors configured to execute program instructions, the execution of which causes the one or more processors to: receiving a plurality of images resulting from scanning the specimen at a plurality of focal planes located along a depth of the specimen, and generating the plurality of images of the volumetric field of view of the specimen at the plurality of focal planes via the detectors of the metrology subsystem; and aggregating the plurality of images to generate volumetric data for the volumetric field of view of the specimen; Weighing system.

2. 2. The metrology system of claim 1, wherein the specimen is formed of a first substrate and a second substrate, the second substrate being bonded to the first substrate at an interface, and the volumetric field of view is located within the specimen.

3. 3. The metrology system of claim 2, wherein the metrology subsystem comprises a Linnik interferometer.

4. 4. The metrology system of claim 3, wherein the Linnik interferometer comprises an infrared interferometer.

5. 4. The metrology system of claim 3, wherein the Linnik interferometer comprises a short wave infrared (SWIR) interferometer.

6. 3. The metrology system of claim 2, wherein the program instructions are further configured to identify one or more voids in the volumetric field of view of the specimen based on the volumetric data, the one or more voids being located at the interface.

7. 3. The metrology system of claim 2, wherein the program instructions are further configured to determine characteristics of one or more voids in the volumetric field of view of the specimen based on the volumetric data, the one or more voids being located at the interface.

8. 3. The metrology system of claim 2, wherein the specimen comprises a die-to-wafer (D2W) bond specimen according to the metrology recipe.

9. 3. The metrology system of claim 2, wherein the specimen comprises a die-to-die (D2D) bond specimen according to the metrology recipe.

10. 3. The metrology system of claim 2, wherein the specimen comprises a wafer-to-wafer (W2W) bonded specimen according to the metrology recipe.

11. 2. The metrology system of claim 1, wherein the volumetric field of view of the specimen includes a volumetric field of a surface profile of the specimen, the specimen being temporarily bonded according to the metrology recipe.

12. 12. The metrology system of claim 11, wherein the volumetric data comprises a height map of the surface topography of the specimen.

13. 12. The metrology system of claim 11, wherein the metrology subsystem comprises a Linnik interferometer.

14. 14. The weighing system of claim 13, wherein the detector is configured to operate in the visible spectral range of light.

15. 14. The metrology system of claim 13, wherein the Linnik interferometer is configured to operate in the infrared spectral range of light.

16. 14. The metrology system of claim 13, wherein the Linnik interferometer is configured to operate in the short wave infrared (SWIR) spectral range of light.

17. 10. The metrology system of claim 1, wherein the volumetric field of view of the specimen includes a volumetric field of a through silicon via (TSV) of the specimen.

18. 10. The metrology system of claim 1, wherein the volumetric field of view of the specimen includes a volumetric field of an overlay target of the specimen.

19. 2. The metrology system of claim 1, wherein said receiving said plurality of images resulting from said scanning of said specimen at said plurality of focal planes comprises: moving the specimen by actuation of a translation stage; moving the reference specimen with the aid of a reference translation stage; and adjusting the phase of the reference beam in the reference arm; A weighing system that includes at least one of the following:

20. 10. The weighing system of claim 1, further comprising a photodiode, the photodiode configured to focus onto the detector.

21. 21. The metrology system of claim 20, wherein the photodiode is configured to receive a photodiode beam from the beam splitter related to the interference between the measurement beam and the reference beam, the photodiode configured to generate specimen positioning data.

22. 22. The metrology system of claim 21, wherein the photodiode beam is derived from the illumination beam from the illumination source and a second illumination beam from a second illumination source.

23. 22. The metrology system of claim 21, wherein the metrology subsystem further comprises a modulator configured to modulate the photodiode beam directed toward the photodiode, the modulator comprising: Binary Phase Filter (BPF), a full width half maximum (FWHM) filter, and Circular mask, A weighing system comprising at least one of the following:

24. 22. The metrology system of claim 21, wherein the metrology subsystem further comprises a modulator configured to modulate the photodiode beam directed toward the photodiode, the modulator comprising a binary phase filter (BPF), a full width at half maximum (FWHM) filter, and an annular mask.

25. 2. A metrology system according to claim 1, wherein the measurement beam directed toward the sample has an area larger than the volumetric field of view of the sample when viewed at one of the plurality of focal planes, and the plurality of images have an imaging area larger than the volumetric field of view of the sample.

26. 10. The metrology system of claim 1, further comprising at least one of a review tool and a patterned wafer geometry (PWG) tool, the PWG tool configured to image the entire surface of the specimen at once; the program instructions are further configured to identify points of interest across the specimen prior to the receiving of the plurality of images; A metering system that takes the points of interest into account when receiving the plurality of images.

27. 27. The weighing system of claim 26, A metrology system wherein the identification of the points of interest is performed using the at least one of the review tool and the patterned wafer geometry (PWG) tool.

28. 28. The metrology system of claim 27, wherein the review tool is an acoustic microscope.

29. 27. The weighing system of claim 26, wherein said identifying said points of interest takes into account user input.

30. 27. The metrology system of claim 26, wherein the program instructions are further configured to monitor a specimen manufacturing process based on the volumetric data.

31. 27. The metrology system of claim 26, wherein the program instructions are further configured to adjust a specimen manufacturing process based on the volumetric data.

32. 10. The metrology system of claim 1, wherein the illumination beam has a first illumination spectral range that overlaps with a second illumination spectral range, and thus the metrology subsystem comprises a multi-wavelength (MWL) metrology subsystem.

33. 33. The metrology system of claim 32, wherein the beam splitter comprises a wavelength filter beam splitter, such that the reference beam has the first illumination spectral range and the measurement beam has the second illumination spectral range.

34. 10. The metrology system of claim 1, wherein the illumination beam comprises an annular illumination beam.

35. 10. The metrology system of claim 1, wherein the illumination beam is shifted across a pupil plane of the metrology subsystem.

36. 1. A method comprising: A specimen is manufactured according to the manufacturing process, wherein the specimen has a surface shape with a concave shape; generating volumetric data of the surface profile of the specimen using a metrology subsystem comprising a detector, wherein the metrology subsystem comprises a Linnik interferometer and the detector comprises a multi-pixel detector; mating the specimen of the surface configuration with a second specimen configured to be mated with the specimen; and adjusting the manufacturing process based on the volumetric data; method.

37. 37. The method of claim 36, further comprising determining a characteristic of the surface shape based on the volumetric data.

38. 37. The method of claim 36, wherein the volumetric data generation is performed in the visible spectrum of light.

39. 37. The method of claim 36, wherein the metrology subsystem comprises an infrared interferometer and the volumetric data generation is performed in the infrared spectral range of light.

40. 40. The method of claim 39, wherein the infrared interferometer comprises a short wave infrared (SWIR) interferometer and the volumetric data generation is performed in the short wave infrared spectral range of light.

41. 1. A method comprising: scanning the specimen at a plurality of focal planes located along a depth of the specimen, and generating a plurality of images of a volumetric field of view of the specimen at the plurality of focal planes in response to a detector in a metrology subsystem, the detector comprising a multi-pixel detector; aggregating the plurality of images to generate volumetric data for the volumetric field of view of the specimen, The method wherein the metrology subsystem comprises a Linnik interferometer.

42. 42. The method of claim 41, wherein the Linnik interferometer comprises an infrared interferometer.

43. 42. The method of claim 41, wherein the Linnik interferometer comprises a short wave infrared (SWIR) interferometer.

44. 42. The method of claim 41, further comprising identifying one or more voids based on the volumetric data.

45. 45. The method of claim 44, further comprising determining a set of candidate volumetric views of the specimen, removing candidate volumetric views from the set of candidate volumetric views based on the volumetric data to generate a refined set of candidate volumetric views, and performing overlay metrology based on the refined set of candidate volumetric views.

46. 45. The method of claim 44, further comprising improving an overlay metrology recipe, the improvement comprising: By generating a performance indicator configured to correlate the one or more voids with overlay metrology results.

47. 42. The method of claim 41, further comprising determining a characteristic of one or more voids based on the volumetric data.

48. 42. The method of claim 41 , wherein the volumetric view of the specimen includes a volumetric view of a through silicon via (TSV) of the specimen.

49. 42. The method of claim 41, wherein the volumetric view of the specimen includes a volumetric view of an overlay target of the specimen.

50. 42. The method of claim 41, wherein said scanning of said specimen at said plurality of focal planes comprises: moving the specimen by actuation of a translation stage; moving the reference specimen by operating a reference translation stage; and adjusting the phase of the reference beam in the reference arm; A method comprising at least one of the following:

51. 42. The method of claim 41, wherein the metrology subsystem comprises a photodiode, the photodiode configured to focus onto the detector.

52. 52. The method of claim 51 , wherein the photodiode is configured to receive a photodiode beam from a beam splitter that is related to interference between a measurement beam in the measurement arm and a reference beam from a reference arm, and wherein specimen positioning data is generated at the photodiode.

53. 53. The method of claim 52, wherein the photodiode beam is derived from the illumination beam from an illumination source and a second illumination beam from a second illumination source.

54. 53. The method of claim 52, further comprising modulating the photodiode beam directed to the photodiode with a modulator, the modulator comprising: Binary Phase Filter (BPF), a full width half maximum (FWHM) filter, and Circular mask, A method comprising at least one of the following:

55. 53. The method of claim 52, further comprising modulating the photodiode beam directed to the photodiode with a modulator, the modulator comprising a binary phase filter (BPF), a full width at half maximum (FWHM) filter, and an annular mask.

56. 42. The method of claim 41, wherein the volumetric field is entirely contained within a cross-sectional area of a metrology beam directed at the specimen, and the volumetric field is fully illuminated.

57. 42. The method of claim 41, further comprising identifying points of interest across the specimen prior to said scanning; The method takes the point of interest into account when generating the plurality of images by scanning the specimen.

58. 58. The method of claim 57, wherein the identifying of the points of interest is performed by at least one of a review tool and a patterned wafer geometry (PWG) tool, the PWG tool configured to image the entire surface of the specimen at once.

59. 59. The method of claim 58, wherein the review tool is an acoustic microscope.

60. 58. The method of claim 57, wherein the identification of the points of interest takes into account user input.

61. 58. The method of claim 57, further comprising monitoring a specimen manufacturing process based on said volumetric data.

62. 58. The method of claim 57, further comprising adjusting a specimen manufacturing process based on the volumetric data.

Images