DEVICE AND METHOD FOR MEASURING PROPERTIES IN A TSV STRUCTURE USING BEAM PROFILE REFLECTOMETRY

Abstract

Method for measuring a property of a silicon through-hole structure, hereinafter referred to as TSV structure, the method comprising: Using a beam profile reflectivity device, hereafter referred to as the BPR device, (400) to move to a first xy position which has a TSV structure; Using the BPR device (400) to achieve optimal focus at the first xy position by setting the z position to a first optimal z position to obtain measurement data at the first xy position; Obtaining reflectivity measurement data via the BPR device (400) for a variety of angles of incidence at the first xy position; and Determining one or more layer thicknesses for the TSV structure based on reflectivity measurement data.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention generally relates to the field of wafer metrology and inspection systems. More specifically, the present invention relates to metrology techniques for TSV (through-silicon via) structures. BACKGROUND

[0002] In general, the semiconductor manufacturing industry involves highly complex techniques for producing integrated circuits using semiconductor materials deposited in layers and in a patterned manner on a substrate, such as silicon. An integrated circuit is usually fabricated starting from a large number of reticles. The creation of reticles and the subsequent optical inspection of such reticles have become standard steps in semiconductor manufacturing. The fabrication of semiconductor devices, such as logic and memory devices, typically involves processing a semiconductor wafer using a large number of semiconductor manufacturing processes, with multiple reticles to form different structures and multiple levels of semiconductor devices. Multiple semiconductor devices can be fabricated in an array on a single semiconductor wafer and then separated into individual semiconductor devices.

[0003] If defects are present on the reticle or wafer, the resulting semiconductor devices may not function properly. Additionally, various structures on the wafer must meet specified specifications or be monitored for quality control purposes. Therefore, there is a constant need for improved measurement mechanisms.

[0004] US 2014 / 0 222 380 A1 relates to a method for the electromagnetic modeling of structures and their illumination, for use in the fields of semiconductor metrology and inspection.

[0005] WO 2013 / 169 791 A1 concerns the simultaneous application of optical scatterometry and small-angle X-ray scattering in the context of metrology applications on samples from the semiconductor industry. OVERVIEW

[0006] The following provides a simplified overview of the disclosure to facilitate a basic understanding of certain embodiments of the invention. This is not a comprehensive overview of the disclosure and does not identify key or critical elements of the invention, nor does it delineate the scope of the invention. Its sole purpose is to introduce some concepts disclosed herein in simplified form as a preparation for the more detailed description that follows.

[0007] An apparatus and method for measuring a property of a silicon through-via (TSV) structure are disclosed. A beam profile reflectivity (BPR) device is used to move to a first position, (x, y), having a TSV structure. The BPR device is then used to obtain an optimal focus at the first position, (x, y), by adjusting the z-position to a first optimal z-position to obtain measurement data at the first position, (x, y). Reflectivity measurement data for a plurality of angles of incidence (AOI) at the first position (x, y) are obtained via the BPR device. One or more layer thicknesses on the TSV structure are determined based on the reflectivity measurement data. A z-position can also be recorded and used to determine a height of such a TSV structure, as well as one or more adjacent positions, (x, y).

[0008] In one particular implementation, the first optimal z-position is recorded by an encoder of the BPR device stage. The BPR device is used to move to a second position, (x, y), adjacent to the TSV structure. The BPR device is then used to achieve optimal focus at the second position, (x, y), by adjusting the z-position to a second optimal z-position to obtain measurement data at the second position, (x, y). The second optimal z-position from the encoder of the BPR device stage is also recorded. Reflectivity measurement data for a plurality of angles of incidence at the second xy position is obtained via the BPR device. One or more layer thicknesses for the second position, (x, y), adjacent to the TSV structure, are determined based on the reflectivity measurement data.A height difference between the TSV structure and the second position, (x, y), is determined based on the recorded first and second optimal z-positions and the layer thicknesses determined for the first and second (x, y) positions. In one aspect, the measurement data for the first and second (x, y) positions are obtained for s- and p-polarization. In another aspect, the layer thicknesses for the first and second (x, y) positions are determined by solving for a set of Fresnel coefficients in a set of Fresnel equations, each of which relates reflectivity, angle of incidence, and thickness. In a further aspect, solving for the set of Fresnel coefficients includes applying a least-squares fitting routine to the set of Fresnel equations and correcting for the absorption properties of one or more layers at the first and second (x, y) positions.

[0009] In another embodiment, for a plurality of adjacent (x, y) positions, the following operations are repeated: using the BPR device to move, using the BPR device to obtain optimal focus, recording an optimal z-position, obtaining reflectivity measurement data, determining one or more layer thicknesses, and determining height differences to obtain a roughness metric for the plurality of adjacent (x, y) positions. In another aspect, the adjacent (x, y) positions cover an area of ​​5-10 micrometers by 5-10 micrometers and larger.

[0010] In an alternative embodiment, the invention relates to a beam profile reflectivity (BPR) system for measuring a property of a silicon through-via (TSV) structure. The system includes an illumination optics module for generating and directing an incident beam onto a sample at a plurality of angles of incidence, a detection optics module for obtaining reflectivity measurement data from the sample in response to the incident beam, and a controller configured to perform one or more of the method operations described above.

[0011] In another embodiment, a cluster system for performing metrology and inspection on a sample is disclosed. The cluster system includes an inspection device for inspecting a sample for defects, any of the above-described embodiments of a BPR system, and a wafer handling system for moving one or more samples between the inspection device and the BPR system. In another embodiment, the cluster system includes a processing device for performing a manufacturing process on a sample, and the wafer handling system is configured to move samples to and from the processing device.

[0012] These and other aspects of the invention are further described below with reference to the figures. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1A is a diagrammatic side view of a substrate via (TSV) process involving the deposition of an interconnect layer on a substrate and within a via. Fig. Figure 1B is a diagrammatic side view of a TSV process after backside etching of the substrate. Fig. Figure 1C is a diagrammatic side view of a TSV process after backside etching of the substrate and deposition of a layer over the TSV structure. Fig. Figure 2 is a diagrammatic top view of a wafer having multiple dies with multiple TSV interconnects on their backside. Fig. 3 is a diagrammatic representation of the incident and outgoing beams in a beam profiling reflectometry (BPR) apparatus according to an embodiment of the present invention. Fig. Figure 4 is a detailed diagrammatic representation of a beam profiling reflectometry (BPR) apparatus in which techniques of the present invention may be employed. Fig. Figure 5 shows the high magnification imaging optics for a BPR system according to one application of the present invention. Fig. 6 is a flowchart illustrating a procedure for determining TSV metrics according to a specific embodiment of the present invention. Fig. Figures 7A to 7H show a process for determining layer thickness using a BPR system. Fig. 8A and Fig. 8B show variants of a combined metrology inspection device according to two embodiments of the present invention. Fig. 9 shows an embodiment of a system for providing illumination to a probe head of a BPR system that utilizes a plurality of illumination sources in accordance with a particular embodiment of the present invention. DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

[0013] The metrology and inspection techniques described herein can be implemented with respect to any suitable specimen. An example of a specimen is a semiconductor structure whose layer thickness is measurable, such as a silicon via (TSV) structure. Specimens can also be semiconductor reticles, solar panels, computer boards, etc.

[0014] A TSV process is typically used to electrically isolate copper vias. A TSV typically extends completely through the wafer or die. TSVs utilize interconnect techniques and offer an alternative to other interconnect technologies, such as wire bonding or flip chips. TSV interconnects can have a comparatively higher density and offer a comparatively shorter interconnect length, for example, from a chip to a board.

[0015] Fig. Figure 1A is a schematic side view of a TSV process. As shown, an interconnect material 104, such as Cu, is deposited on a substrate 102 and within a via region 104a. The via may be formed by any suitable process, such as drilling or etching through the silicon. The via may have any suitable dimension, such as 100 to 200 µm deep and 50-100 µm in diameter. The substrate is then etched on the backside to expose a portion of the interconnect material to form a silicon via (TSV) as shown in Fig. 1B. The substrate 102 may initially have a thickness of approximately 750 µm and then be etched to expose the Cu in the via.

[0016] In one embodiment, substrate 102 is a silicon wafer substrate. In other examples, the substrate may include any suitable bulk semiconductor material, such as germanium, silicon carbide, indium arsenide, gallium arsenic, indium phosphate, etc. Substrate 102 may also include an epitaxial layer over the bulk semiconductor material. The epitaxial layer may be a germanium layer over the bulk silicon, or another silicon layer overlying the bulk silicon-germanium.

[0017] The substrate 102 may also include other overlying structures or doped regions. Additionally, other semiconductor, insulating, and conductive layers may be patterned onto the substrate 102 and the interconnect TSV layer 104. The doped regions and other patterned materials together form various devices (such as metal-insulator-semiconductor field-effect transistor (MOSFET) devices), isolation structures (such as dielectric isolation structures, such as shallow trench isolation or STI structures), etc.

[0018] As in Fig. As shown in Figure 1B, the Cu region 104b of TSV 104a is exposed on the backside of substrate 102. This TSV 104a and its exposed region 104b may have various problems that are preferably detected and closely monitored, as connection problems can be detrimental to the device's function. For example, the via hole may be drilled such that the via is tilted and not perpendicular to the substrate surface. The TSV 104a may have an irregular shape, contain voids, or exhibit roughness at its exposed region 104b.

[0019] Fig. Figure 1C is a schematic side view of a TSV process after backside etching of the substrate and deposition of a layer 107 over the TSV structure. As shown, the TSV structure is no longer exposed but covered with layer 107. In one example, this layer 107 is a dielectric layer deposited over the wafer's TSV structures during the final device formation process, forming dielectric caps for the TSVs, e.g., with a height of 104d.

[0020] One metrology goal may be to characterize the extent to which the Cu extends beyond the wafer backside (or a measurement of 104c). This means that the height of this extension 104c often needs to be within strict specifications. Another goal may be to measure the extent of the TSV cap (e.g., 104d).

[0021] Fig. 2 is a schematic top view of a wafer 202 with multiple dies (such as 204a-e), each having multiple TSV interconnects on their backside (not shown). The different dies or die regions may have different associated TSV characteristics, such as differences in the aforementioned TSV dimensions 104c or 104d. For example, one die 204a may have TSVs that do not extend all the way through the substrate. Another die 204b may have TSVs that extend a short distance from the backside surface, while another die 204c may have TSVs that extend a greater amount from the backside.

[0022] The measurement of the TSV extension height can be accomplished using a profile metrology fixture, such as the Micro3000 metrology module from KLA-Tencor in Milpitas, CA. This fixture measures the difference between focal points and the corresponding movement of the fixture in the z-direction to determine the extent of each TSV. Although measuring such extents with this type of fixture is a slow process, such measurement data can be easily obtained if the TSV extends only through a silicon substrate. However, measurement problems can arise if the backside of the silicon substrate is also covered with one or more layers of different material (e.g., 106 in Fig. 1B), which can make it difficult to determine the focal point for the different coating(s) (e.g., 106) relative to the focal point on the exposed surface (104b) of the TSV. For example, some of the layers may be transparent, while other layers are opaque to the optical incident light from the metrology device.

[0023] Certain embodiments of the present invention use a beam profiling reflectometry (BPR) device to measure properties of TSV structures. Fig. Figure 3 is a schematic representation of the incident and outgoing beams in a BPR device according to an embodiment of the present invention. In this typical BPR device, one or more lenses (e.g., beam splitter 304) serve to collimate the incident light 302 and focus it onto a spot on the sample 306. The incident beam 302 can be focused substantially perpendicular to the surface of the sample 306 to minimize the spot size and maximize resolution.

[0024] The individual rays of the incident beam bundle 302 have different angles of incidence, depending on the numerical aperture of the illumination lens. In a BPR system, the numerical aperture is large, approximately 0.9, which causes the incoming incident rays to strike the sample 306 at a wide range of angles, approximately 0° to 65°. Each light beam strikes the wafer at a specific angle. This angle depends on the position of the beam in the beam bundle. For example, the reflected beam 302a is reflected by the beam splitter 304 at a perpendicular angle with respect to the surface of the sample 306. The perpendicular angle (0 degrees) corresponds to an axis 308 that is perpendicular to the sample surface. Other incident rays, such as 302b, have a larger angle of incidence upon striking the sample surface. These light rays have a wide range of angles of incidence on the sample.In this figure, one beam (center of the beam) has an angle of incidence of 0° (perpendicular to the wafer), while the other beams have larger angles of incidence, approximately 50°. In one embodiment, the wavelength of the light is approximately 6730 Å.

[0025] The output light beams 310 reflected by the sample 306 pass through one or more lenses (e.g., beam splitter 304) and are detected by one or more detectors, such as the detector array 312. The array detector is configured to detect beams as a function of the angle of incidence. That is, each pixel position imaged on the sample by an incident beam at a specific angle of incidence corresponds to a detected pixel on the array detector. That is, each detected pixel corresponds to a different angle of incidence. For example, there may be 512 pixel measurements, where each pixel is a measurement of the reflectivity as a function of the angle of incidence.

[0026] Fig. Figure 4 is a detailed schematic representation of a beam profiling reflectometry (BPR) system 400 in which techniques of the present invention may be implemented. System 400 may include one or more light sources (e.g., 402a and 402b) for directing light onto a sample 410. Any suitable number and type of light sources may be employed. For example, light source 402a may be a laser diode (e.g., 673 nm), and light source 102 may be a white light source.

[0027] The incident light can be directed through any type and number of beam splitters and lenses (e.g., 404a, 404b, 409) designed, sized, and shaped to direct and focus a variety of different angles of incidence onto a specific spot on sample 410. In one embodiment, laser light source 402a generates a beam of 673 nm or less that has multiple angles of incidence and is then collimated and focused onto sample 410.

[0028] System 400 may also include any suitable number and type of beam splitters and lenses (e.g., 404b, 404c, 404d, 404e, 404f) to direct output light reflected from sample 410 in response to the incident beam to one or more detectors or sensors (e.g., 406a, 406b, 406d, 406e). The detectors may be, for example, array A detector 406a, array B detector 406b, reflected laser light detector 406c, autofocus detector 406d, and video camera 406e. Array A and array B detectors may be arranged to detect both S and P polarity of the reflected light (e.g., array A is perpendicular to array B). The autofocus detector is used to detect whether the sample is positioned at the focal point of the laser beam. The autofocus signal is used to move a z-stage until a predetermined autofocus signal is found.The system 400 may also include an incident light power meter 406.

[0029] The system 400 may also include controller 412, which serves to control various components of the system. For example, the controller 412 may include one or more processors and memory. The processor(s) and memory of the controller may be programmed to control and adjust various settings of the system. Each processor may typically include one or more microprocessor integrated circuits and may also include integrated interface and / or memory circuits and may additionally be coupled to one or more shared and / or global memory devices. The processor(s) and memory of the controller may also be configured to receive output signals or images from the detectors and analyze such data for the purpose of defect detection or metrology.

[0030] The controller may also include a positioning mechanism to move the stage onto which the sample is placed. The autofocus module and the positioning mechanism of the controller may work together to position the sample stage to obtain optimal focus. By any suitable mechanism, the illumination optics column may be moved relative to the stage in an x, y, and / or z direction, and / or the stage may be moved in an x, y, and / or z direction relative to the optics column to scan fields of the reticle. For example, a motor mechanism may be used to move the stage. The motor mechanism may, for example, be formed from a screw drive and stepper motor, a linear drive with position feedback, or a belt actuator and stepper motor.

[0031] The positioning mechanism generally also includes one or more encoders that can be read to determine the x, y, or z position of the stage and sample, which are then used to determine a TSV height as further described herein.

[0032] The array detectors can be used to measure light corresponding to any angle of incidence or a small set of angles of incidence, as well as to both linearly s-polarized and p-polarized light. For example, each array pixel can detect light reflected or scattered by the sample in response to an incident beam striking such a sample at a specific angle of incidence. Fig. Figure 5 shows the high-magnification imaging optics for a BPR system according to one application of the present invention. For example, the system magnification is set to 100x. Here, h0 is the height of a parallel light beam above the main optical axis, F1 is the focal point, and θ1 is the angle of the beam that passed through h0 as it passed through F1 (e.g., lens 409). For the BPR, the light from the sample surface again passes through the high-magnification lens, which bends the light beam back to parallelism. The distance h0 from the center of the laser spot, the angle θ1, and the effective focal length F1 satisfy the equation: h0 / F1=sin(θ1)

[0033] In a BPR system, there may be an additional relay lens that magnifies the image of the laser cross-section. If M is the magnification factor and D p is the distance from the center of the enlarged laser spot at the pixel array, then h0=D p / M.

[0034] D p =Pixel # (from center) x PW (pixel width), thus: (Pixels #)×(PW) / (MxF1)=sin(θ1)

[0035] Since the expression (PW) / (MxF1) tends to be constant for any array, two expressions, α for array A and β for array B, can be defined: For array A:(Pixel#from the center of array A)×0.01×α=sin(θA) For array B:(Pixel # from the center of array B)×0.01×β=sin(θB)

[0036] The numerical aperture (NA) for a lens is related to the largest angle at which light is focused for a lens system. For array A:NA=(Maximum pixels # from the center of array A−1)×0.01×α=Sin(θMax) For array B:NA=(Maximum pixels # from the center of array B−1)×0.01×β=Sin(θMax)

[0037] For example, the minimum allowable numerical aperture for the BPR can be chosen to be approximately 0.84.

[0038] BPR technology can be used to measure the polarized reflectance of a surface as a function of the angle of incidence by imaging the back focal plane of a high NA (typically 0.95) lens onto array detectors. The angular variation functions can also be measured at a given wavelength, providing rich information for determining layer thicknesses and other optical properties without requiring a model or considering any assumptions. Due to the high NA and use of a laser source, the BPR system also has a very high spatial resolution (-0.5 µm) and can therefore provide adequate accuracy to measure even a rough surface where layer thicknesses vary on a microscopic scale.Due to the high spatial resolution and high measurement speed of a BPR system, an area on the surface can be scanned to determine the thickness variation across the scanned area. Thus, the actual surface roughness can be measured and resolved. The contribution of each layer to such thickness variation can also be determined. Again, due to the high NA design, the BPR system can provide very precise height sensitivity. In one version, the autofocus (AF) mechanism is also designed to guide the light through the lens with a high degree of accuracy.

[0039] Any suitable technique may be employed to use the BPR system to measure a TSV property, such as the height (e.g., 104c or 104d) relative to the surrounding layer surface (e.g., 106 or 107). Fig. 6 is a flowchart illustrating a method 600 for determining TSV metrics according to a specific implementation of the present invention. First, process 600 includes moving to an xy position at the top of a first TSV in operation 602. For example, the beam path is moved relative to the first TSV structure on the sample so that it impinges on the first TSV (sample and / or beam column optics moved). The locations of each TSV structure may be provided by the designers (e.g., in a GDSII file) and entered into the inspection machine, which automatically moves to a first TSV position, or an operator may manually initiate such movement of the inspection machine to a first location.

[0040] An autofocus signal can then be used to adjust a z-position to achieve optimal focus, in operation 604. For example, a portion of the output beam can be received in the autofocus detector (e.g., 406d) and used to generate an autofocus signal, which is analyzed to determine if the z-position needs to be adjusted to achieve more optimal focus. A specific z-position can be achieved by moving the stage up and down via a positioning mechanism (e.g., 412). Optimal focus can be achieved, for example, when the signal from a two-cell detector located after a knife chopper is balanced at the desired focus position of the reflected laser beam. The z-position can also be recorded, in operation 604.For example, an encoder xyz position (located on the table) can be read and recorded / stored in memory for later use in conjunction with the current TSV.

[0041] BPR measurements at the current xyz position are then obtained in operation 606. That is, BPR measurements are obtained at different angles of incidence. These BPR measurements are then used to determine layer thicknesses (e.g., t1, t2, etc.) for one or more layers at the xy position in operation 608. For example, a linear array detector may be operable to detect 512 pixels or 512 measurements at different angles of incidence. That is, reflectivity is measured as a function of the angle of incidence, and these reflectivity measurements are then analyzed together to determine layer thickness values.

[0042] Any suitable technique can be used to determine layer thicknesses from BPR measurements. Fig. Figures 7A to 7H show a process for determining film thicknesses using a BPR system. For a single air-film interface, Fig. 7A, that a portion of the incident light (702) is reflected at the air / layer interface as reflected light (704), and a portion is refracted into the layer as refracted light (706). The reflected light (704) plus the refracted light (706) is equal to the incident light (702). Furthermore, the ratio of the reflected light and the refracted light depends on the angle of incidence, the index n1 of the layer, and the plane of incidence. In this case, the index n1 is greater than 1; the reflected light is 40%, and the refracted light is 60% for a given angle i and a given plane of incidence.

[0043] A light beam can be represented as a wave that has a vibrational or oscillatory component. This oscillation is always perpendicular to the direction of propagation, as in Fig. 7B shows the incident beams 710a and 710b, which have propagation directions 712 and polarization directions 714. Additionally, the oscillation period in space is the wavelength of light. An ordinary light beam is unpolarized. That is, this ordinary unpolarized beam has oscillations that occur randomly in all possible planes containing the propagation direction.

[0044] Fig. Figure 7C shows a beam of unpolarized light 720 perpendicular to a plane 722. The arrows (shown on plane 722) symbolize some of the directions of the oscillations. A beam of linearly polarized light has oscillations only in one plane (e.g., 724). A polarizer converts unpolarized light into linearly polarized light. An analogy is a grid of thin parallel wires through which the unpolarized light passes. The light polarized parallel to the wires is absorbed, so that the transmitted light only has a polarized component perpendicular to the wires. The wire grid polarizer is a classic polarizer, and other types of polarizers, such as those based on birefringent crystals or thin-film coatings, are available and can be used. Examples include a Glan-Thomson polarizer or a cube polarizer (e.g., 726 in Fig. 7C).

[0045] If the plane of incidence is perpendicular to the polarization direction (i.e., the oscillations are in a plane perpendicular to the plane of incidence), then the plane of incidence is said to be an s-plane, and the beam is said to be s-polarized. Fig. 7D shows an s-polarized direction 732 for an incident beam 734 in plane of incidence 736. If the plane of incidence 736 of another incident beam 742 includes the polarization direction, 738 (ie, the light vibrates in the plane of incidence 736), then the plane of incidence (736) of the incident beam (742) is a p-plane, and the beam is said to be p-polarized.

[0046] Fig. Figure 7E shows the theoretical variation of the ratio of (reflected amplitude) / (incident amplitude) as a function of the angle of incidence. Note that for an angle of incidence of 0° (normal beam), the reflected amplitudes are equal for s- and p-polarization (refl / incid = Ro). For s-polarized light, the intensity of the reflected light increases with the angle of incidence. For p-polarized light, the intensity initially decreases and then increases.

[0047] The Brewster angle (iB) is the angle of incidence for which the reflected intensity for p-polarized rays is 0. While the amplitudes can change sign and become negative, the intensities measured by the BPR system (intensity = square of the amplitude) are always positive. The dotted curve in Fig. 7E corresponds to what the BPR system effectively measures.

[0048] At the Brewster angle, no p-polarized light is reflected from the film, and all incident p-polarized light is refracted into the film, then reflected from the substrate and exits as ray #2. For a thin film, the offset between ray #1 and ray #2 is very small and coherently superposed. For this angle of incidence, iB, there is no reflected ray #1. However, as explained below, the BPR system measures and simulates ray #1, ray #2, and all subsequent reflected rays to determine the film thickness as shown in Fig. 7F shown.

[0049] The Brewster angle generally depends on the index of the air and the index of the layer, according to the following relationship: tan(iB)=n1 / n0

[0050] The value at this angle provides information about the index n1 of the layer. For the air / oxide interface, iB = 55°. For air / nitride: iB = 63°, and for air / polySi: iB = 75°.

[0051] Light can be described by a wave or oscillation. Each wave has an amplitude, a wavelength, and a phase. Next, two interfaces in the form of air / layer and layer / substrate are considered, as shown in Fig. 7F. Ray #1 is the ray reflected at the upper interface, and ray #2 is the ray refracted into the layer, reflected from the substrate, and exited from the upper interface.

[0052] After leaving the slice, the reflected beams #1 and #2 are parallel (same angle i). Since the slice thickness t is small in this example (e.g., 1 µm), the two beams are practically coincident. If a detector detects both reflected beams, it would measure the sum of their oscillation amplitudes.

[0053] Beam #2 traveled a longer distance (2d within the film for the central beam) than beam #1. The additional distance (2d) was within the film. This distance is traveled by beam #2 at a lower speed than in air due to the higher refractive index n1 of the film. This additional distance results in a delay between the oscillation phases of the two beams. At a given point, where beams #1 and #2 are parallel to each other outside the sample, the maximum amplitude of beam #1 may not coincide with the maximum amplitude of beam #2. That is, they may not oscillate in phase.

[0054] Beam 1 and beam 2 are in phase if their phase difference is a multiple of the period of the light wave. The sum of the two beams 1 and 2 is then maximum: amplitude of beam 1 + amplitude of beam 2 (constructive interference). In contrast, beam 1 and beam 2 are in antiphase if the oscillation of beam 1 is at its maximum when the oscillation of beam 2 is at its minimum. In this latter case, the sum of the two beams 1 and 2 at a minimum is: amplitude of beam 1 - amplitude of beam 2 (destructive interference).

[0055] This phase delay depends on the length 2d of the additional path, the speed v of light propagation in the layer, the angle of incidence, and the wavelength of the light. The additional path 2d, in turn, depends on the thickness t of the layer and the angle r, where r is related to the angle i (Snell's law). The speed v of propagation of the light wave in the layer is v=c / n1 where c is the speed of light in vacuum (or in air) and n1 is the index of the layer.

[0056] In the layer, ray #2 travels at a lower speed than in air. The period of the wave in space varies as does the speed. The larger the index, the smaller the speed and the smaller the period in space. The intensity of the reflected light depends on the angle of incidence i of the light, the refractive index n of the layer, the extinction coefficient k of the layer, the layer thickness t, the wavelength λ of the light, and the polarization of the light.

[0057] In summary, the angle of incidence for light depends on which part of the lens is used to focus the light. The BPR system generally focuses a collimated, cylindrical beam of incident light rays into a spot of 0.9 or 0.7 micrometers in size over a range of angles of incidence. Since the reflected angle is equal to the angle of incidence, the output lens also collimates the reflected light beam. Incident light is both reflected and refracted at each interface, and the angles of reflection and refraction at each interface depend on the corresponding angle of incidence. For each angle of incidence, thin-film interference determines the measured reflected intensity. Since the incident beam is also linearly polarized, the polarization direction (S, P, or mixed) can then be selected by choosing a specific plane that intersects the incident or reflected beam.Arrays A and B can then be oriented to detect light that is only S-polarized or only P-polarized, respectively. The resulting signal is reflectivity versus angle, as shown in . Fig. 7G for array A or s-polarized reflectivity.

[0058] These reflectivity measurements at different angles of incidence can then be used to determine one or more layer thickness values. For example, as in Fig. As shown in Figure 7H, the thickness t1 at xy position 750a (at the top of the TSV post) can be determined. Any suitable technique can be used, such as solving for the Fresnel coefficients. Information about the layer thickness is specifically derived by using the measured reflectance information in a mathematical model or a set of equations relating reflectance, angle of incidence, and layer thickness. The equations used are based on the well-known Fresnel equations. The essential equation for the reflectivity of a sample with respect to S-polarized light is as follows: RS=|rS1+rS2ei2k1t1+rS1⋅rS2⋅ei2k1t|2

[0059] Wherein R s is the reflectivity of the light, which is derived from the isolated intensity measurement, the refractive index in air is assumed to be unity, and t is the thickness of the layer. The constant k in equation [1] is given by the equation: k1=2πλnLcosθL where λ is the wavelength of the light beam. All r values ​​are for the reflectivity of s-polarized light, where r S1 is the reflectance from the top surface of the thin layer and r S2 is the reflectance from the interface between layer and substrate.

[0060] For S-polarized light, the reflectivity from the surface of the thin layer (r S1 ) and the substrate (r S2 ) is given by the following equations: rS1=(nLcosθL−cosθ0nLcosθL+cosθ0) rS2=(nScosθS−nLcosθLnScosθS+nLcosθL) where n L the refractive index of the thin layer, n s the refractive index of the substrate, θ0 the angle of incidence at the interface between air and the surface of the thin film, θ L the angle of incidence into the thin layer and θ S is the angle of incidence into the substrate.

[0061] For P-polarized light, the reflectivity from the surface of the thin layer (r P1 ) and the substrate (r P2 ) is given by the following equations: rP1=[nLcosθL−1cosθOnLcosθL+1cosθO] rP2=[nScosθS−nLcosθOnScosθS−nLcosθO]

[0062] The detected reflectivity of p-polarized light is RP=|rP1+rP2⋅ei2k1t1+rP1⋅rP2⋅ei2k1t|2

[0063] The thickness of a thin film can be derived based on a best fit of the simulated reflectance, using Equations [1]–[7], to the measured reflectance values ​​obtained as a function of the angle of incidence as described above. For multiple layers on a substrate, Equations [1] to [7] can be applied recursively to determine the reflectivity of the entire layer stack. Many nonlinear optimization algorithms can be used to determine the best fit, such as the Gauss-Newton or LM method.

[0064] The accuracy of the result can be further improved if an analysis is performed that takes into account factors such as light absorption by the sample and the effect of a finite detector size. The extent of absorption varies from material to material. If the materials are known, various correction factors can be included in equations 1 and 7 to further refine the determination. The absorption correction can be easily made by changing the index n. S , n L in equations [1] - [7] by n S +ik S and n L +ik Lis replaced, and thus all mathematical operations are based on complex numbers, where k is the imaginary part of the index related to the absorption coefficient. A numerical solution can be sought, for example, by applying a least-squares fitting routine. Such a numerical analysis is greatly facilitated by the fact that an approximate solution for the layer thickness is usually known from the process information. Thus, a least-squares fitting routine can be used to solve a set of Fresnel equations, inputting the probable solution for the layer thickness. By refining the solution in this way, the accuracy of the measurement can be significantly improved.

[0065] The above operations are repeated for an xy position adjacent to the current TSV to obtain signals from a region of the surface that does not include the TSV. In the example of Fig. 1B, an adjacent position on the surface 106 may be located next to the TSV region 104a. In Fig. 1C may be an adjacent position on the surface 107. Back to Fig. 6, process 600 includes moving to an xy position adjacent to the current TSV in operation 610. The autofocus signal is used to adjust the z position to obtain optimal focus and record the z position for the current xy position in operation 612. BPR measurements are then obtained at this current adjacent xyz position in operation 614. These BPR measurements are also used to determine the slice thicknesses for the adjacent position (e.g., T1, T2, .... etc.) in operation 616. For example, as in Fig. 7H, thickness values ​​for T1 and T2 are determined for the xy position 750b, which is adjacent to the TSV structure.

[0066] Because the spot size is quite small (e.g., 0.7 micrometers), the thicknesses will not vary significantly. In certain embodiments, the process 600 may be repeated for each position in a particular scan area, such as an area that is approximately 5-10 micrometers by 5-10 micrometers. The spot may be moved relative to this particular area in increments of, for example, 1 micrometer. Thus, many sets of measurement data are obtained for a particular TSV area, and this measurement data may be used to determine multiple sets of thicknesses for the particular area.

[0067] The height of the TSV (above the surrounding layer surface) can also be determined, based on top and neighboring measurement results, recorded z-positions, and specified layer interface properties, in operation 618. That is, the thicknesses and z-positions obtained for the two xy-positions can be used to determine the relative height of such xy-positions.

[0068] For example, the difference between the recorded heights of the first and second xy positions can be specified as a height for the TSV structure. This height can also be specified relative to a user-defined z-reference value. For example, as in Fig. As shown in Figure 7H, the z-reference value can be set to the top of the layer with thickness T2. Generally, the recorded z-position refers to the z-position of the stage at which the autofocus signal provides a desired value, for which the focal point of the real beam is typically located in the center of the layer stack. The position of the actual surface relative to the focal point of the beam can be determined by an algorithm that takes the determined thickness values ​​for each xy-position as input. The relative height of multiple xy-positions can also be used as a metric for roughness.

[0069] Back to Fig. 6, it can then be determined in process 620 whether there are additional TSV structures. If there are more TSV structures, process 600 is repeated for the next TSV structure. Otherwise, the process ends.

[0070] Certain embodiments of the present invention utilize a BPR system with a small spot size, which provides adequate spatial resolution and thus high accuracy for measuring layer thicknesses and relative heights (or roughness metrics) for a rough surface. The high spatial resolution is associated with the high NA characteristic of the typical BPR system layout. The small spot size and high measurement speed allow scanning an area and measuring multiple points within that area, enabling the measurement of surface roughness with high spatial resolution and isolating the roughness of different layers of the layer. The BPR system is used to measure reflectance variation as a function of angle of incidence (AOI), providing a rich set of information that enables the simultaneous measurement of layer thicknesses and optical properties without the need for a dispersion model.Certain techniques described herein also provide a way to measure feature height with high accuracy because (a) the high NA system provides high sensitivity to height, and (b) each of the layer thicknesses can be isolated by analyzing the BPR signal.

[0071] The BPR system can be designed as a standalone system or integrated into a cluster machine. In one specific implementation, a combination system enables the measurement of TSV thickness on a semiconductor wafer using BPR and the measurement of other metrology features (e.g., CD, overlay, layer composition, etc.) or defect detection using reflectivity, electromagnetic scatterometry waveform, or scanning electron microscope (SEM) images or signals on the same metrology system or using linked metrology systems that share at least part of a robotic wafer handling system. The processes for measuring the properties of the TSV structure and other metrology or inspection features can be planned and performed on separate metrology systems.A disadvantage of methods for measuring such properties on separate measurement systems is the additional time required to plan and execute separate operations on separate metrology machines. Another disadvantage is the redundancy of shared components and the associated costs.

[0072] To overcome these disadvantages, a metrology system can be provided that combines BPR and inspection / metrology. In one embodiment, the BPR and inspection / metrology systems can be separate systems that can operate independently of each other, but are connected to share at least part of a robotic wafer handling system.

[0073] In operation, a wafer, a group of wafers, or a stack of multiple wafers can be introduced into the combined metrology system by loading the wafer container onto the robotic wafer handling system dedicated to this combined metrology / inspection system. Measurement recipes can be selected that specify BPR measurements on some or all of the wafers and other metrology / inspection measurements on some or all of the wafers. The BPR measurements and the other metrology / inspection measurements can be specified together in one or more recipes, or can be specified in separate recipes. The BPR and other metrology / inspection measurements can be performed on the same wafers or on different wafers, or on some of the same wafers and some different wafers. The BPR and other metrology / inspection systems can operate in parallel or in series.

[0074] Another example of a combined metrology system would be a connected system comprising a BPR system, another metrology / inspection system, such as one manufactured by KLA-Tencor of Milpitas, CA, a robotic handling system, and a wafer scheduling system. A BPR system can also be integrated with a processing machine. Communication with factory automation and / or factory information and / or factory process control systems can be accomplished through separate communication or automation systems, or can be at least partially or completely shared.

[0075] One advantage of the combined BPR and other metrology / inspection system is the reduction in the overall time required to complete the scheduling and / or execution of BPR and other measurements. At least one queue delay can be eliminated.

[0076] Fig. 8A and Fig. 8B show variants of a combined metrology / inspection device 800 and 801, respectively, according to two embodiments of the present invention. In both figures, the combined metrology / inspection device includes a robotic wafer handling system 802, a BPR module 804, another metrology / inspection module 806, a wafer loading position A 808, and a wafer loading position B 810.

[0077] The robotic wafer handling system 802 is configured to transfer wafers to and from the BPR module 804 and metrology / inspection module 806, as well as to and from the wafer loading positions A 808 and B 810. The BPR module 804 is configured to measure TSV properties, such as height, layer thickness, and roughness, etc. The metrology / inspection module 806 may be configured to detect defects or measure any metric, such as overlay or critical dimensions, such as line width, top line width, via diameter, repose angle, and profile. The wafer loading position A and the wafer loading position B are configured to contain one or more wafers. In most cases, they contain a plurality of wafers. The wafers may be from the same or different lots.

[0078] In a specific embodiment, system 800 includes an inspection device system (806) for obtaining intensity signals or images from a wafer. For example, the inspection device may construct an optical image or generate intensity values ​​from a portion of the wafer based on a portion of detected light reflected, transmitted, or otherwise directed to one or more light sensors. The inspection device may then output the intensity values ​​or images, as well as encoder position data, for defect detection analysis.

[0079] In Fig. 8A and Fig. 8B, the BPR module 804 and the metrology / inspection module 806 are separate systems connected via the robotic wafer handling system 802.

[0080] The BPR module can have any suitable form, such as the BPR system 400 of the Fig. 4. The inspection / metrology module can take any suitable form for inspecting a sample using one or more electromagnetic waveforms to measure a property of the sample or to detect defects on such a sample. Examples of an inspection system include specially configured 29xx, 8xxx, or 3xxx inspection system families available from KLA-Tencor of Milpitas, California.

[0081] In one process, some of the wafers from wafer load position A and / or B have TSV properties measured at the BPR module 804, and then other metrology or inspection properties measured at the metrology / inspection module 806. The wafer can be measured by both processes without being removed from the system, thus reducing wafer handling and associated throughput issues. In another operation, some wafers from wafer load position A and / or B have TSV properties measured at the BPR module 804, and some other wafers from wafer load position A and / or B have other metrology or inspection properties measured at the metrology / inspection module 806. In each of these operations, the BPR and metrology / inspection modules can operate independently and concurrently.

[0082] A group of wafers may initially be received by either the BPR module 804 or the inspection / metrology module 806. For example, the wafers may be a wafer lot loaded at position A 808. The TSV properties of a wafer from the group of wafers are measured by the BPR module 804. Another metrology or inspection process may then be performed by the metrology / inspection module 806 on a wafer from the group of wafers. Such BPR and other metrology / inspection processes may be performed on different wafers at the same time. The transfer of the wafer may, for example, be performed by the Fig. 8A and Fig. 8B. Once all measurements have been performed, the group of wafers is released from the metrology device, for example, at position B 810.

[0083] The BPR systems described above are not intended to limit the scope of the invention. The inventive techniques described herein may be applied to any suitable BPR system, such as the system of Fig. 4. In an alternative embodiment, the BPR system includes an illumination system capable of generating multiple wavelength ranges. In some embodiments of the disclosure, illumination beams from a plurality of illumination sources are combined to provide illumination at one or more selected wavelengths to the probe head. Different wavelength ranges can be selected for different layer or substrate materials that become opaque or transparent at different wavelength ranges. That is, the wavelength ranges that cause one or more of the test area layers to be transparent can be selected.

[0084] Several embodiments of multi-wavelength, multi-angle-of-incidence detectors that can be used in the systems shown are further described in U.S. Patent 7,667,841 B2, issued February 23, 2010, to Jon Opsal and U.S. Patent 5,596,411, issued January 21, 1997, to Jeffrey T. Fanton et al., which are incorporated herein by reference in their entirety for all purposes. Fig. Figure 9 shows one embodiment of a system 900 for providing illumination to a probe head of a BPR system employing a plurality of illumination sources 902 according to a specific embodiment of the present invention. Illumination from the illumination sources 902 may be combined to travel along a common illumination path using a plurality of dichroic combiners 910. In one embodiment, the dichroic combiners 910 are configured to direct illumination along a clear illumination beam path. In some embodiments, at least a portion of the illumination beam path may be provided by one or more optical elements, such as focusing lenses, beam splitters, combiners, mirrors, coupling lenses, optical fibers, attenuators, polarizers, collimating lenses, and the like.

[0085] In one embodiment, the system 900 includes, but is not limited to, a first illumination source 902A, a second illumination source 902B, a third illumination source 902C, a fourth illumination source 902D, a fifth illumination source 902E, and a sixth illumination source 902F. Each illumination source 902 may be configured to provide illumination at a selected wavelength or wavelength range. In one example embodiment, the first illumination source 902A, the second illumination source 902B, the third illumination source 902C, the fourth illumination source 902D, the fifth illumination source 902E, and the sixth illumination source 902F may be configured to provide illumination at a wavelength of 488 nm, 685 nm, 443 nm, 638 nm, 405 nm, and 532 nm, respectively.The above embodiment is provided for illustrative purposes and should not be construed as limiting the present disclosure. In other embodiments, illumination sources 902 configured to provide illumination at an alternative set of wavelengths may be selected.

[0086] The illumination sources 902 may be configured to transmit illumination through respective collimating lenses 904 to a guide path defined by optical elements, including, but not limited to, folding mirrors 908 and dichroic combiners 910. The system 900 may further include shutters 906 disposed between the illumination sources 902 and the guide path. The shutters 906 may be configured to allow the transmission of illumination from at least one selected illumination source 902 to the guide path while blocking illumination from other illumination sources 902.In one embodiment, a shutter 906 corresponding to an illumination source 902 emitting illumination at a selected wavelength may open to transmit illumination at the selected wavelength, while all other shutters 906 remain closed to block illumination at other wavelengths emanating from the other illumination sources 902.

[0087] In one embodiment, the guide path may include, but is not limited to, two deflection mirrors and five dichroic combiners in the Fig.9 and described herein. A first deflection mirror 908A may be configured to reflect illumination from the first illumination source 902A to a first dichroic combiner 910A. A second deflection mirror 908B may be configured to reflect illumination from the second illumination source 902B to a second dichroic combiner 910B.

[0088] A dichroic combiner 910 may be configured to transmit illumination at wavelengths above or below a selected threshold and reflect illumination at other wavelengths. Alternatively, a dichroic combiner 910 may be configured to transmit illumination at wavelengths within or outside a selected range and reflect illumination at other wavelengths. The first dichroic combiner 910A may be configured to transmit illumination from the first illumination source 902A to a third dichroic combiner 910C. The first dichroic combiner 910A may be further configured to reflect illumination from the third illumination source 902C to the third dichroic combiner 910C.

[0089] The second dichroic combiner 910B may be configured to transmit illumination from the second illumination source 902B to a fourth dichroic combiner 910D. The second dichroic combiner 910B may be further configured to reflect illumination from the fourth illumination source 902D to the fourth dichroic combiner 910D.

[0090] The third dichroic combiner 910C may be configured to transmit illumination from the first illumination source 902A and illumination from the third illumination source 902C to a fifth dichroic combiner 910E. The third dichroic combiner 910C may be further configured to reflect illumination from the fifth illumination source 902E to the fifth dichroic combiner 910E.

[0091] The fourth dichroic combiner 910D may be configured to transmit illumination from the sixth illumination source 902F to the fifth dichroic combiner 910E. The fourth dichroic combiner 910D may be further configured to reflect illumination from the second illumination source 902B and illumination from the fourth illumination source 902D to the fifth dichroic combiner 910E.

[0092] The fifth dichroic combiner 910E may be configured to transmit illumination from the second illumination source 902B, illumination from the fourth illumination source 902D, and illumination from the sixth illumination source 902F along the illumination path to the measuring head of the optical metrology system. The fifth dichroic combiner 910E may be further configured to reflect illumination from the first illumination source 902A, illumination from the third illumination source 902C, and illumination from the fifth illumination source 902E along the illumination path to the measuring head.

[0093] In one embodiment, the illumination path may include one or more polarizing beam splitters 912, 916 arranged before and / or after an intensity control module 914. The intensity control module may include an electro-optical element, such as a Pockels cell, configured to attenuate the intensity of the illumination delivered to the measurement head along the illumination path. At least one polarizing beam splitter 916 may be configured to direct a portion of the illumination along a feed path to a single-mode or multimode optical fiber 922, which is configured to deliver the portion of the illumination to a polarization channel of the measurement head.The polarizing beam splitter 916 may further be configured to direct at least a further portion of the illumination along an additional delivery path to an optical fiber 936, which is configured to deliver the additional portion of the illumination to an additional polarization channel of the measuring head. The delivery paths may include additional optical elements to define a path and / or control illumination traveling along the path. For example, a deflection mirror 930 may be configured to reflect illumination along a selected path. Shutters 918, 932 may be configured to selectively pass or block illumination delivered to the optical fibers 922, 936. Coupling lenses 920, 934 may be configured to transfer illumination from free space to the optical fibers 922, 936.A beam splitter 924 may be configured to direct a small portion of the illumination from the illumination beam path or delivery path to a wavelength monitor 928 through a lens 926, optical fiber, and / or any other optical elements. The above examples are provided for illustrative purposes only. It is contemplated that various optical elements may be included or excluded without departing from the essence of the present disclosure.

[0094] In this and other systems, a two-dimensional detector can be used instead of the two linear arrays, or instead of each linear array, to capture more detected information and achieve a more robust solution. Furthermore, different axes of a 2D detector can be used for different angles of incidence and different wavelength ranges. Other types of detectors include four-cell detectors, CCD arrays, etc.

[0095] In general, to obtain encoder position data, an instruction can be sent to the table encoder system to record xyz position data into one or more encoder buffers, and then another instruction is sent to the table encoder system to unload or "write" the xyz position data from the encoder buffers to system memory.

[0096] If the xyz encoder system can also be instructed to record real-time xyz encoder position data and write such data to system memory when a strip is scanned, special firmware can be configured to enable bidirectional communication in real time. Alternatively, a sequential read / write technique would also work, allowing the system to utilize the scan reversal time for writing and receiving the xyz encoder position data.

[0097] Regardless of the system configuration, one or more controllers may be used to control various aspects of the system. For example, the signals sensed by each sensor may be processed by a control system, such as one or more signal processing devices, each of which may include an analog-to-digital converter configured to convert analog signals from each sensor into digital signals for processing. The control system may include one or more processors coupled to input / output ports and to one or more memories, via suitable buses or other communication mechanisms.

[0098] The control system may also include one or more input devices (e.g., a keyboard, mouse, joystick) for providing user input, such as changing the focus and other metrology and / or inspection recipe parameters. The control system may also be connected to the stage positioning mechanism, for example, to control a sample position (e.g., focusing and scanning), and may be connected to other inspection / metrology system components to control other inspection parameters and configurations of such components.

[0099] The control system may be configured (e.g., with program instructions) to provide a user interface (e.g., a computer screen) to display resulting intensity values, images, and other inspection / metrology results. The control system may be configured to generate images and / or other displayed signals. The control system may be configured (e.g., with program instructions) to provide a user interface (e.g., on a computer screen) to display resulting intensity values, images, diagrams, projections, and other inspection / metrology properties. In certain embodiments, the control system is configured to perform metrology and / or inspection techniques discussed above.

[0100] Since such information and program instructions may be implemented on a specially designed computer system, such a system includes program instructions / computer code for performing various operations described herein, which may be stored on a non-transitory computer-readable medium. Examples of machine-readable media include, but are not limited to, magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROM disks; magneto-optical media such as optical disks; and hardware devices specifically designed to store and execute program instructions, such as read-only memory (ROM) and random access memory (RAM). Examples of program instructions include both machine code, such as generated by a compiler, and files containing higher-level code that can be executed by the computer using an interpreter.

Claims

[1] A method for measuring a property of a silicon via structure, hereinafter referred to as TSV structure, the method comprising: Using a beam profile reflectivity device, hereinafter referred to as BPR device, (400) to move to a first xy position having a TSV structure; Using the BPR device (400) to achieve an optimal focus at the first xy position by setting the z position to a first optimal z position for obtaining measurement data at the first xy position; Obtaining reflectivity measurement data via the BPR device (400) for a plurality of angles of incidence at the first xy position; and Determining one or more layer thicknesses for the TSV structure based on the reflectivity measurement data. [2] The method of claim 1, further comprising: Recording the first optimal z-position from an encoder of the stage of the BPR device (400); Using the BPR device (400) to move to a second xy position adjacent to the TSV structure; Using the BPR device (400) to achieve an optimal focus at the second xy position by setting the z position to a second optimal z position for obtaining measurement data at the second xy position; Recording the second optimal z-position from the encoder of the stage of the BPR device (400); Obtaining reflectivity measurement data via the BPR device (400) for a plurality of angles of incidence at the second xy position; Determining one or more layer thicknesses for the second xy position adjacent to the TSV structure based on the reflectivity measurement data; and Determining a height difference between the TSV structure and the second xy position based on the recorded first and second optimal z positions and the layer thicknesses determined for the first and second xy positions. [3] Method according to claim 2, wherein the measurement data for the first and second xy positions are obtained for s and p polarization. [4] The method of claim 2, wherein the layer thicknesses for the first and second xy positions are determined by solving for a set of Fresnel coefficients in a set of Fresnel equations, each of which relates reflectivity, angle of incidence and thickness. [5] The method of claim 4, wherein the solution to the set of Fresnel coefficients includes applying a least squares fitting routine to the set of Fresnel equations and correcting for the absorption properties of one or more layers at the first and second xy positions. [6] The method of claim 4, further comprising repeating the operations of using the BPR device (400) to move, using the BPR device (400) to obtain an optimal focus, recording an optimal z-position, obtaining reflectivity measurement data, determining one or more layer thicknesses, and determining height differences for a plurality of adjacent xy positions to obtain a roughness metric for the plurality of adjacent xy positions. [7] The method of claim 6, wherein the adjacent xy positions cover an area of ​​approximately 5-10 micrometers by 5-10 micrometers or more. [8] Beam profile reflectivity system, hereinafter referred to as BPR system, (400) for measuring a property of a silicon via structure, hereinafter referred to as TSV structure, comprising: an illumination optics module for generating and directing an incident beam onto a sample (410) at a plurality of angles of incidence; a detection optics module for obtaining reflectivity measurement data from the sample (410) in response to the incident beam; and a controller (412) configured to perform the following operations: Move to a first xy position that has a TSV structure; Achieving an optimal focus at the first xy position by setting the z position to a first optimal z position for obtaining measurement data at the first xy position; Obtaining reflectivity measurement data for a variety of angles of incidence at the first xy position; and Determining one or more layer thicknesses for the TSV structure based on the reflectivity measurement data. [9] System (400) according to claim 8, wherein the controller (412) is further configured to Recording the first optimal z-position from an encoder of the BPR device table; Move to a second xy position adjacent to the TSV structure; Achieving an optimal focus at the second xy position by setting the z position to a second optimal z position for obtaining measurement data at the second xy position; Recording the second optimal z-position from the encoder of the stage of the BPR device (400); Obtaining reflectivity measurement data for a variety of angles of incidence at the second xy position; Determining one or more layer thicknesses for the second xy position adjacent to the TSV structure based on the reflectivity measurement data; and Determining a height difference between the TSV structure and the second xy position based on the recorded first and second optimal z positions and the layer thicknesses determined for the first and second xy positions. [10] The system (400) of claim 9, wherein the measurement data for the first and second xy positions are obtained for s and p polarization. [11] The system (400) of claim 9, wherein the layer thicknesses for the first and second xy positions are determined by solving for a set of Fresnel coefficients in a set of Fresnel equations, each of which relates reflectivity, angle of incidence, and thickness. [12] The system (400) of claim 11, wherein the solution to the set of Fresnel coefficients includes applying a least squares fitting routine to the set of Fresnel equations and correcting for absorption properties of one or more layers at the first and second xy positions. [13] The system (400) of claim 11, wherein the controller (412) is further configured to repeat the operations of using the BPR device (400) to move, using the BPR device (400) to obtain an optimal focus, recording an optimal z-position, obtaining reflectivity measurement data, determining one or more layer thicknesses, and determining height differences for a plurality of adjacent xy positions to obtain a roughness metric for the plurality of adjacent xy positions. [14] The system (400) of claim 13, wherein the adjacent xy positions cover an area of ​​approximately 5-10 micrometers by 5-10 micrometers or more. [15] The system (400) of claim 8, wherein the illumination optics module is configured to generate the incident beam at a plurality of wavelength ranges, and the controller (412) is further configured to select a wavelength range for particular slice types. [16] Cluster system for performing metrology and inspection on a sample (410), comprising: an inspection device (806) for inspecting a sample (410) for defects; the BPR system (400) according to claim 8; and a wafer handling system (802) for moving one or more samples (410) between the inspection device (806) and the BPR system (400). [17] Cluster system for performing metrology and processing on a sample (410), comprising: a processing device for performing a manufacturing process on a sample (410); the BPR system (400) according to claim 8; and a wafer handling system (802) for moving one or more samples (410) between the processing device and the BPR system (400).

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