Wafer bonding overlay measurement system

Abstract

A method for overlay measurement is disclosed. The method includes receiving an image of a bonded wafer. The method includes generating a contour of the bonded wafer based on the image. The method includes using the contour to adjust an objective lens of an infrared (IR) system based on a single focus image to perform an overlay measurement on the bonded wafer.

Description

Cross-reference of relevant patents and applications

[0001] This application claims the benefit of U.S. non-provisional application No. 18 / 410,770, filed January 11, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to the fabrication of microelectronic devices, including semiconductor devices, transistors, and integrated circuits, including methods for overlay measurements on bonded wafers. Background Technology

[0003] The semiconductor industry has experienced rapid growth due to the ever-increasing integration density of various electronic components, such as transistors, diodes, resistors, capacitors, etc. In most cases, this increase in integration density stems from the continuous reduction in the minimum feature size, which allows more components to be integrated into a given area. With the recent growth in demand for miniaturization, higher speeds and greater bandwidth, as well as lower power consumption and latency, the need for improved warp characterization and control has also increased. Summary of the Invention

[0004] Wafer-to-wafer and chip-to-chip bonding is being implemented to continue power-performance-area-cost (PPAC) scaling of complex circuits, such as those implemented in a system-on-a-chip (SoC). Wafer bonding can be performed using at least one suitable bonding technique, such as, but not limited to, direct wafer bonding, anodic bonding, fused bonding, adhesive bonding, eutectic bonding, metal diffusion bonding, or glass frit bonding. During wafer bonding, bonding measurements can be performed to check for alignment (or misalignment) or to measure overlay between wafers. Overlay measurements are performed at the bonding interface of the bonded wafers. Overlay measurements are performed using an infrared (IR) bonding overlay measurement system based on a single-focus image (e.g., sometimes referred to as an optical system or IR system). However, because IR systems are single-focus (e.g., designed or configured with a fixed focal length or focus), overlay or warpage measurements may potentially be impossible if the warpage is greater than or exceeds a certain depth of field of the IR system, such as greater than a predefined micrometer of the IR system's capabilities. Furthermore, the use of autofocus can reduce / lower the throughput of measurement overlay, since vertical scanning is performed before capturing individual images of the bonded wafer.

[0005] The systems and methods described herein provide various embodiments for positioning objectives (or optical lenses) in a single-focus IR system to measure overlay measurements on bonded wafers. These systems and methods can adjust the objective positioning without the need for autofocus (e.g., without vertical scanning of the entire bonded wafer). For example, these systems and methods can scan the low spatial frequency warp (or other types of imaging) of the bonded wafer. These systems and methods can map the scan of the low spatial frequency warp to generate a profile (e.g., a topographic profile) of the warp presented in the bonded wafer. These systems and methods can adjust the objective according to this profile to follow the topography, allowing the objective to be positioned at or near a predefined distance from the bonded wafer (or the bonding interface of the bonded wafer). After adjusting the objective, these systems and methods can capture at least one image of the bonding interface for overlay measurements. Therefore, these systems and methods can utilize the profile of the bonded wafer to adjust the objective to perform overlay measurements on one or more bonded wafers. In this way, this disclosure avoids the use of autofocus or vertical scanning, thereby increasing the throughput of overlay measurements.

[0006] One embodiment may include a method for measuring overlay. The method includes receiving an image of a bonded wafer. The method includes generating a profile of the bonded wafer based on the image. The method includes using the profile to adjust an objective lens of an infrared (IR) system based on a single-focus image to perform overlay measurements on the bonded wafer.

[0007] In some embodiments, the profile includes the topography of the bonded wafer. Adjusting the objective lens includes adjusting the objective lens along the topography of the bonded wafer to perform overlay measurements on the bonded wafer. In some embodiments, the topography of the bonded wafer is determined without the need for vertical scanning of the bonded wafer.

[0008] In some embodiments, generating the profile includes: scanning at least the low spatial frequency components of the warped area of ​​the bonded wafer; and mapping the warped low spatial frequency components onto an image of the bonded wafer to generate the profile. In some embodiments, adjusting the objective lens includes adjusting the objective lens to a position having a predefined focal length from the bonded wafer according to the profile; and in response to adjusting the objective lens, using the objective lens to obtain at least one image of the bonded wafer at that position.

[0009] In some embodiments, the bonded wafer includes a first wafer and a second wafer interconnected. Overlay measurement includes overlay markings between the first and second wafers. In some embodiments, the method includes receiving a second image of the second bonded wafer. The method includes using the profile to adjust an objective lens to perform overlay measurements on the second bonded wafer. In some embodiments, the variation between a first morphology of the bonded wafer and a second morphology of the second bonded wafer is within a predefined range.

[0010] In some embodiments, the method includes storing the contour of the bonded wafer in a lookup table in response to generating the contour. In some embodiments, receiving an image of the bonded wafer includes scanning at least one of the x-axis or y-axis of the bonded wafer to generate the image.

[0011] Another embodiment may include a measurement system comprising at least one processor. The at least one processor is configured to receive an image of the bonded wafer. The at least one processor is configured to generate a profile of the bonded wafer based on the image. The at least one processor is configured to use the profile to adjust the objective lens of an infrared (IR) system based on a single-focus image to perform overlay measurements on the bonded wafer.

[0012] In some embodiments, the profile includes the morphology of the bonded wafer. To adjust the objective lens, the at least one processor is configured to adjust the objective lens along the morphology of the bonded wafer to perform overlay measurements on the bonded wafer. In some embodiments, the morphology of the bonded wafer is determined without requiring a vertical scan of the bonded wafer.

[0013] In some embodiments, to generate a profile, the at least one processor is configured to scan at least the warped low spatial frequency components of the bonded wafer. The at least one processor is configured to map the warped low spatial frequency components onto an image of the bonded wafer to generate the profile. In some embodiments, to adjust the objective lens, the at least one processor is configured to adjust the objective lens to a position having a predefined focal length from the bonded wafer according to the profile. In response to adjusting the objective lens, the at least one processor is configured to use the objective lens to obtain at least one image of the bonded wafer at that position.

[0014] Another embodiment may include an apparatus. The apparatus includes an inspection system comprising at least one processor configured to: receive an image of a bonded wafer; and generate a profile of the bonded wafer based on the image. The apparatus includes a single-focus image-based infrared (IR) system comprising an objective lens configured to use the profile to adjust the objective lens to perform overlay measurements on the bonded wafer.

[0015] In some embodiments, the bonded wafer includes a first wafer and a second wafer interconnected, and wherein the overlay measurement includes overlay markings between the first wafer and the second wafer. In some embodiments, the at least one processor is further configured to receive a second image of the second bonded wafer. The single-focus IR system is further configured to use the profile to adjust the objective lens to perform overlay measurements on the second bonded wafer.

[0016] In some embodiments, the variation between the first morphology of the bonded wafer and the second morphology of the second bonded wafer is within a predefined range. In some embodiments, the storage device is configured to store the contour of the bonded wafer in a lookup table in response to contour generation.

[0017] These and other aspects and implementations are discussed in detail below. The above information and the following detailed description include illustrative examples of various aspects and implementations, and provide an overview or framework for understanding the nature and characteristics of the claimed aspects and implementations. The accompanying drawings provide illustration and further understanding of the various aspects and implementations, and are incorporated into and constitute a part of this specification. Aspects may be combined, and it will be readily understood that features described in the context of one aspect of the invention may be combined with other aspects. Aspects may be implemented in any convenient form. As used in the specification and claims, unless the context clearly indicates otherwise, the singular forms “a / an” and “the” include plural references. Attached Figure Description

[0018] Non-limiting embodiments of this disclosure are described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale. Unless indicated as representing prior art, the drawings represent various aspects of this disclosure. For clarity, not every component may be labeled in each drawing. In the drawings:

[0019] Figure 1 An IR system with single focus and autofocus functions is shown, which captures images of a bonding interface according to some embodiments.

[0020] Figure 2 A flowchart illustrating an example method for overlay measurement according to some embodiments is shown.

[0021] Figures 3A to 3B Utilization according to some embodiments is illustrated Figure 2 The method is used to perform each stage of the overlay measurement.

[0022] Figure 4 The movement of an objective lens for focusing on a bonding interface is demonstrated according to some embodiments.

[0023] Figure 5 It is a block diagram illustrating the architecture of a computer system, including components that can be used to implement the systems and methods described and shown herein, such as... Figures 1 to 3B The various aspects of the overlay measurement system are described in the text. Detailed Implementation

[0024] Reference will now be made to the illustrative embodiments depicted in the accompanying drawings, and these embodiments will be described herein in specific language. However, it will be understood that this is not intended to limit the scope of the claims or this disclosure. Changes and further modifications to the inventive features shown herein, as well as additional applications to the principles of the subject matter presented herein, that would occur to those skilled in the art and to those who have obtained this disclosure, will be considered within the scope of the subject matter disclosed herein. Other embodiments and / or other variations may be used without departing from the spirit or scope of this disclosure. The illustrative embodiments described in the detailed description are not intended to limit the subject matter presented.

[0025] In some systems, wafer-to-wafer and chip-to-chip bonding is being implemented to continue PPAC scaling of complex circuits. Wafer bonding can be performed using at least one suitable bonding technique, such as, but not limited to, direct wafer bonding, anodic bonding, fused bonding, adhesive bonding, eutectic bonding, metal diffusion bonding, or glass frit bonding. In some scenarios, misalignment, overlay, or morphology can be observed at the bonding interface between wafers during wafer bonding. The bonding interface refers to the area where two or more wafers are joined or bonded together. The bonded wafers form a bonded wafer, sharing connectivity at the bonding interface. To measure overlay (e.g., misalignment or morphology), some systems can utilize a single-focus IR bonding overlay measurement system, such as at least in... Figure 1 As shown in the image.

[0026] Figure 1 An IR system with a single focus function 100 and an autofocus function 101 is shown, which captures images of a bonding interface according to some embodiments. Figure 1 It may include at least a bonding interface 102 for bonding wafers, and various depths of field 104a to 104g (e.g., sometimes referred to as depth of field 104). Depth of field refers to the range of distances at which an object appears in focus in the resulting image (e.g., an image of an object captured at a relatively high resolution). Figure 1 The bonding interface 102 can be a symbolic representation (or cross-section) of the interface between wafers. In the single-focus function 100, the objective lens 106 can be positioned at a predefined vertical position to capture an image of the bonding interface 102. When the content of the image (e.g., a portion of the bonding interface 102) is within the depth of field 104 of the objective lens 106, the objective lens 106 can capture an image at a relatively high resolution. As shown for the single-focus function 100, the objective lens 106 can transition or move horizontally (e.g., along the x-axis or y-axis) to capture an image of the bonding interface 102. However, if the warpage of the bonding interface 102 is greater than the depth of field of the IR system, for example... Figure 1As shown, the objective lens 106 of the IR system may not be able to capture a relatively sharp image of the bonding interface 102 (e.g., the image may be blurry or out of focus). For example, by positioning the objective lens 106 in a fixed or predetermined vertical position, its depth of field 104 can be in a similar vertical range or depth across various x-axis or y-axis planes when capturing an image of the bonding interface 102. In such cases, some portions of the bonding interface 102 (e.g., with some level of warping) may not be within the depth of field 104, and therefore the objective lens 106 may not be able to capture images of some portions of the bonding interface 102 (such as those corresponding to depths of field 104a, 104c to 104e and 104g) for overlay measurements.

[0027] Some systems can utilize the autofocus function 101. For example... Figure 1 As shown, one or more scanning techniques can be used to scan the bonding interface 102 vertically (e.g., along the z-axis of the bonded wafer) to identify focal points across the entire bonding interface 102. For example, the identified focal points can represent the positioning of the objective lens 106 such that the focal point is within the depth of field 104. The objective lens 106 can be moved or adjusted vertically (e.g., along the z-axis) and horizontally (e.g., along the x-axis or y-axis) based on the focal points. However, utilizing the autofocus function 101 may reduce the throughput or rate of data acquisition (e.g., image capture) of the bonding interface 102 by collecting multiple samples of focal points across the entire bonding interface 102, merging samples, and determining the positioning of the objective lens 106 based on the merged samples to capture images. This is because a vertical scan of the entire set of distances is performed before capturing / images. Therefore, the system and method of this technical solution provide various embodiments for positioning the objective lens 106 of a single-focus IR system to measure the overlay of bonded wafers.

[0028] According to one embodiment, a process for measuring the overlay of a bonded wafer is provided. This process may involve adjusting the positioning of the objective lens 106 to conform to the morphology (e.g., morphological profile or morphological map) or characteristics of the bonding interface 102 without utilizing an autofocus function 101 (e.g., without vertically scanning the entire bonded wafer). For example, images of the bonded wafer or bonding interface 102 can be captured by devices or tools such as surface profilometers, optical profilometers, scanning acoustic microscopy (SAM), Mohr interferometry, digital holography, or X-ray imaging. The images may be at least one of an X-axis scan or a Y-axis scan of the bonded wafer. In some cases, the tool used to capture the images may be part of a computing device (or measurement system), such as, but not limited to, [other types of devices]. Figure 5The computing device / system 500, in response to performing a scan, can identify or obtain the morphology or visual attributes / characteristics of the bonded wafer. The computing device can map the scan (e.g., including morphology) of the bonding interface 102 of the bonded wafer to generate a profile (e.g., sometimes referred to as a wafer profile or morphology profile). Based on the profile, the computing device can adjust the position of the objective lens 106 according to the morphology of the bonding interface 102 without using the autofocus function 101. In some embodiments, morphology information (e.g., morphology profile or morphology map) can be obtained by using at least one suitable metrology tool. Therefore, the throughput for capturing images of the bonding interface 102 can be increased and optimized.

[0029] Figure 2 A flowchart of an example method 200 for overlay measurement is shown. It should be noted that method 200 is merely an example and is not intended to limit the scope of this disclosure. Accordingly, it should be understood that other methods can be applied. Figure 2 Method 200 provides additional operations before, during, and after, and some other operations may be described only briefly in this article.

[0030] In various embodiments, the operation of method 200 can be associated with various stages 300, 301 to perform overlay measurements, such as, but not limited to, Figures 3A to 3B As shown below, this will be discussed in further detail. It should be understood that the operation of method 200 can be performed by a computing device, tool, or component (e.g., [example device]) configured to have the capabilities to perform the features or functions discussed herein. Figure 5 The operation of method 200 may be performed by a computing device / system 500. For simplicity and for the purpose of providing examples herein, the operation of method 200 may be performed by a computing device that may include, correspond to, a measurement system, an inspection system, or a single-focus IR system including objective lens 106, or be part of such systems. Although in Figures 3A to 3B A single objective lens 106 is shown, but multiple objectives 106 may be implemented to capture images of the bonding interface 102. In some cases, the single-focus IR system including objective lens 106 or other components may be external to the computing device. In such cases, the computing device may transmit or provide instructions to external components, such as adjusting the positioning of objective lens 106 of the single-focus IR system to capture, for example, an image of the bonding interface 102. This document may include other components, devices, or systems to perform the operations of method 200. In summary, method 200 may include receiving / obtaining / acquiring an image of the bonded wafer at operation 202. At operation 204, method 200 may include generating a profile of the bonded wafer. At operation 206, method 200 may include adjusting / changing / configuring objective lens 106.

[0031] Corresponding to Figure 2 Operations 202 to 206, Figures 3A to 3BStages 300 and 301 for performing overlay measurements are shown. At operation 202, a computing device (e.g., a measurement system or inspection system) can receive an image of the bonded wafer. The bonded wafer may include at least a first wafer and a second wafer bonded to each other, wherein the bonding interface 102 is the connection between the first wafer and the second wafer. The bonding between the first wafer and the second wafer can be performed using at least one suitable bonding technique, such as at least one of direct bonding, fused bonding, adhesive bonding, anodic bonding, etc. The bonding interface 102 may represent a portion of the bonded wafer, and is not limited to, for example... Figure 1 or Figures 3A to 3B At least one of those shown in the document. Although the bonding interface 102 is presented as a crescent shape for simplicity and for the purpose of providing examples herein, the bonding interface 102 may include other shapes, not limited to flat interfaces, curved interfaces, stepped interfaces, gap interfaces, or combinations of various types of interfaces.

[0032] A computing device can obtain an image of a bonded wafer by performing a scan on the bonded wafer. The computing device can pre-scan the bonded wafer, for example, in response to the bonding of a first and second wafer or before providing the bonded wafer to a single-focus IR system for imaging. In some aspects, the computing device can receive images of the bonded wafer from a storage device (e.g., a data repository or data storage device) that stores at least an image of the bonded wafer, or from a scanner that scans the bonded wafer. To scan the bonded wafer, the computing device or scanner can utilize at least one suitable scanning or imaging technique, such as, but not limited to, optical profilometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), SAM, confocal microscopy, X-ray imaging, or laser scanning profilometry. Scanning can be performed on the x-axis and y-axis of the bonded wafer to generate an image.

[0033] For example, a computing device (e.g., using a scanner) can perform a scan on at least the bonded wafer to identify or obtain low spatial frequency components of warping in the bonded wafer (or the bonding interface 102 of the bonded wafer). Warped low spatial frequency components refer to warping or deformation occurring in certain regions or wavelengths (e.g., on the surface of the bonded wafer). For example, warped low spatial frequency components can represent gradual changes or undulations in the wafer shape extending over various regions or ranges. For example, warped low spatial frequency components can correspond to or include the topography 302 (or shape) of the bonded wafer or bonding interface 102. The scan can correspond to or be used to generate an image of the bonded wafer. In some embodiments, an image of the bonded wafer can refer to a scan of the bonded wafer. In some cases, the image can include a visual representation (e.g., structure) of the bonded wafer.

[0034] At operation 204, a computing device (e.g., a measurement system or inspection system) can generate a profile (e.g., a first profile) of the bonded wafer based on an image. The profile can refer to a wafer profile or a topographic profile, etc. For example, the computing device can scan the bonded wafer to identify warped low spatial frequency components or the topography 302 of the bonded wafer. In response to identifying the warped low spatial frequency components, the computing device can map the warped low spatial frequency components onto an image of the bonded wafer. For example, by mapping the warped low spatial frequency components onto an image of the bonded wafer (e.g., a visual representation), the computing device can generate a profile representing or including the association between the warped low spatial frequency components and the structure of the bonded wafer. The association between the warped low spatial frequency components and the structure of the bonded wafer can correspond to associating the identified topography 302 with the bonding interface 102 of the bonded wafer to generate a profile (e.g., a topographic profile), such as... Figure 3A As shown in stage 300.

[0035] For example, Figure 3A Stage 300 illustrates the bonding interface 102 of the bonded wafer, which has a specific morphology 302 or shape identified based on a scan of the bonded wafer. In response to scanning the bonded wafer and mapping the scan onto an image of the bonded wafer, a computing device can obtain or identify the morphology 302 of the bonded wafer with respect to the bonding interface 102 as part of a contour. Thus, the contour of the bonded wafer can include, indicate, or represent the morphology 302 of the bonding interface 102, which can be used to position the objective lens 106. The morphology 302 of the bonded wafer can be determined or identified without vertically scanning the bonded wafer (or bonding interface 102) (e.g., along the z-axis of the bonded wafer).

[0036] In various cases, the computing device may store the profile of the bonded wafer in a lookup table in response to the generation of the profile. For example, the computing device may store the profile in a local or external storage device or memory. The computing device may retrieve the profile from the storage device. In some cases, other authorized devices may access the profile from the storage device. For example, the profile may be retrieved by an IR system (e.g., a single-focus IR system) to perform adjustments to the objective lens 106 based on the profile. The computing device may retrieve the profile from the lookup table using a key generated, for example, based on an identifier, the warp characteristics of the bonded wafer (e.g., measurements, shape, etc.), a timestamp, the tool or machine used for bonding or analyzing the first and second wafers, or other fingerprints associated with the bonded wafer. In some cases, the computing device (e.g., an IR system) may use a profile (such as the same profile generated from the bonded wafer) for another bonded wafer or another bonding interface associated with a different bonded wafer in the same semiconductor package (e.g., a stack of wafers manufactured or bonded using the same machine, equipment, or tools, etc.).

[0037] At operation 206, a computing device (e.g., an IR system) can use this profile to adjust the position of objective lens 106 (e.g., a vertical position, such as up and down relative to the surface of the wafer) to perform overlay measurements on the bonded wafer. The computing device can command or instruct the IR system to adjust the position of objective lens 106 to capture an image of the bonding interface 102 along topography 302. For example, it can be... Figure 3B At least stage 301 shows the adjustment of the objective lens 106 for capturing images.

[0038] For example, such as Figure 3B As shown, the profile may include the topography 302 along the bonding interface 102 of the bonded wafer. Using this profile, a computing device may instruct an IR system (or other components configured to position the objective lens 106) to adjust the objective lens 106 along the topography 302 of the bonding interface 102 of the bonded wafer to perform overlay measurements on the bonded wafer. Adjusting the objective lens 106 may include adjusting the positioning of the objective lens 106 (e.g., sometimes referred to as a lens) according to or following the profile (e.g., a topography map via pre-scanned wafer data) to achieve a predefined focal length from the bonding interface 102 of the bonded wafer. With a predefined focal length between the objective lens 106 (e.g., the lens of a lens) and the bonding interface 102, a portion of the bonding interface may be within the depth of field 104.

[0039] For example, it can be combined, but is not limited to Figure 4 To describe an example of adjusting objective lens 106. For example, Figure 4 Illustration 400 depicts an example movement of objective lens 106 for focusing on bonding interface 102 (e.g., along topography 302). As shown, objective lens 106 can be adjusted along the z-direction to position it within region 402a, such that a portion of bonding interface 102 is within the depth of field 104 of objective lens 106. Objective lens 106 can be adjusted along the x-direction and / or y-direction to capture an image of a second portion of bonding interface 102. Similarly, objective lens 106 can be adjusted along the z-direction to position it within region 402b, such that the second portion is within the depth of field 104 of objective lens 106. Objective lens 106 can be adjusted along the x-direction, y-direction, and / or z-direction to position it within region 402c, such that a third portion of bonding interface 102 is within the depth of field 104 of objective lens 106, and so on.

[0040] In response to adjusting objective lens 106, a computing device (e.g., a single-focus IR system) can command or use objective lens 106 to acquire or capture at least one image of the bonded wafer at each corresponding location following topology 302. By following the profile (e.g., topology 302), the computing device (e.g., a single-focus IR system) can obtain a relatively sharp, focused image of the bonding interface 102 from objective lens 106. Using the images captured by objective lens 106, the computing device can perform overlay measurements to measure wafer bonding overlay errors. For example, overlay measurements may include one or more overlay marks between a first wafer and a second wafer. The computing device can analyze these marks to determine any misalignment between wafer bonds, such as misalignment between the first wafer and the second wafer. According to, but not limited to, the operation of method 200, the computing device (or various components discussed herein) can integrate various tools to adjust the objective lens 106 according to the topography 302 (at a single focal length) for capturing a focused image of the bonding interface 102 without utilizing autofocus features (e.g., autofocus function 101), thereby optimizing image data acquisition, minimizing resource consumption and avoiding vertical scanning of the bonded wafer.

[0041] In some configurations, the computing device may receive a second image of the second bonded wafer. For example, the second bonded wafer may include a second bonding interface formed between a third wafer and a fourth wafer. In some cases, the second bonded wafer may include a second bonding interface between a third wafer and a first wafer or between a fourth wafer and a second wafer. The second image may include a scan of the structure of the second bonded wafer. In some cases, the second bonded wafer may be part of the same semiconductor package (e.g., the same product) as the bonded wafer between the first and second wafers (e.g., the first). In some cases, the computing device may determine that the variation between the morphology 302 of the bonded wafer and the second morphology of the second bonded wafer is within a predefined range; for example, the bonded wafer includes a warped pattern similar to that of the second bonded wafer (e.g., according to the scan), such as within a predefined micrometer. In cases where the second bonded wafer originates from the same semiconductor package or includes a warp pattern similar to that of the bonded wafer (e.g., similar to bonding interface 102), the computing device can use the same contour (e.g., a first contour) of bonding interface 102 to adjust objective lens 106 to capture an image of the second bonding interface of the second bonded wafer. Because the warp pattern is similar between bonded wafers, the bonding interfaces of these bonded wafers can be within a depth of field 104 associated with the contour. In response to this adjustment, the computing device can perform overlay measurements on the second bonded wafer.

[0042] In some aspects, the second bonded wafer may not originate from the same semiconductor package and may not include similar warp patterns. In such cases, the computing device may iterate over the various operations of method 200, such as generating a second profile associated with the second bonded wafer. The computing device may store the second profile, which includes a second morphology of the second bonding interface of the second bonded wafer, in a storage device. In such cases, the computing device may adjust the objective lens 106 based on the second profile (e.g., the second morphology) to capture an image of the second bonding interface.

[0043] Figure 5 This is a block diagram of an example computer system 500. The computer system or computing device 500 may include or be used to implement any computing device, processing system, or components thereof. The computing system 500 includes at least one bus 505 or other communication components for transmitting information and at least one processor 510 or processing circuitry coupled to the bus 505 for processing information. The computing system 500 may also include one or more processors 510 or processing circuitry coupled to the bus for processing information. The computing system 500 also includes at least one main memory 515, such as random access memory (RAM) or other dynamic storage device, coupled to the bus 505 for storing information and instructions to be executed by the processor 510. The main memory 515 may also be used to store location information, utility grid data, command instructions, device status information, environmental information within or outside the utility grid, information about power characteristics, or other information during the execution of instructions by the processor 510. The computing system 500 may further include at least one read-only memory (ROM) 520 or other static storage device coupled to the bus 505 for storing static information and instructions for the processor 510. Storage device 525 (such as a solid-state device, disk or optical disk) can be connected to bus 505 to persistently store information and instructions.

[0044] The computing system 500 can be connected to a display 535, such as a liquid crystal display or an active matrix display, via a bus 505 for displaying information to users (such as data processing systems or public power grid administrators). An input device 530 (such as a keyboard or voice interface) can be connected to the bus 505 for transmitting information and commands to the processor 510. The input device 530 may include a touchscreen display 535. The input device 530 may also include cursor controls, such as a mouse, trackball, or arrow keys, for transmitting directional information and command selection to the processor 510 and for controlling cursor movement on the display 535. The display 535 may be part of a computing device or other components configured to perform the operations of method 200.

[0045] The processes, systems, and methods described herein can be implemented by a computing system 500 in response to a processor 510 executing instruction means contained in main memory 515. Such instructions may be read into main memory 515 from another computer-readable medium, such as storage device 525. Executing the instruction means contained in main memory 515 causes the computing system 500 to perform the illustrative processes described herein. One or more processors in a multiprocessing device may also be used to execute the instructions contained in main memory 515. Hardwired circuitry may be used in place of or in combination with software instructions in conjunction with the systems and methods described herein. The systems and methods described herein are not limited to any particular combination of hardware circuitry and software.

[0046] Although already Figure 5 An example computing system is described herein, but the subject matter including the operations described herein may also be implemented in other types of digital electronic circuit systems, or in computer software, firmware, or hardware (including the use of the structures disclosed herein and their structural equivalents), or in a combination of one or more of the foregoing.

[0047] In the foregoing description, specific details, such as the particular geometry of the machining system and the description of the various components and processes used therein, have been set forth. However, it should be understood that the techniques described herein can be practiced in other embodiments departing from these specific details, and such details are for illustrative purposes rather than limiting. The embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, specific figures, materials, and configurations have been set forth for illustrative purposes to provide a thorough understanding. However, embodiments can be practiced without such specific details. Components having substantially the same functional construction are indicated by similar reference numerals, and therefore any redundant descriptions may be omitted.

[0048] Various techniques have been described as multiple discontinuous operations to aid in understanding the various embodiments. The order of description should not be construed as implying that these operations must be performed in sequence. In fact, these operations do not need to be performed in the presented order. The described operations may be performed in an order different from the order of the described embodiments. In additional embodiments, various additional operations may be performed and / or the described operations may be omitted.

[0049] As used herein, "substrate" or "target substrate" generally refers to the object being processed according to the present invention. A substrate may include any material portion or structure of a device (particularly a semiconductor or other electronic device) and may be, for example, a base substrate structure (such as a semiconductor wafer, a photomask), or a layer on or overlying a base substrate structure (such as a thin film). Therefore, a substrate is not limited to any particular base structure, underlying layer, or overlying layer, whether patterned or unpatterned, but is contemplated to include any such layer or base structure, and any combination of layers and / or base structures. This description may refer to specific types of substrates, but this is for illustrative purposes only.

[0050] Those skilled in the art will also understand that many changes can be made to the operation of the techniques explained above while still achieving the same objectives of the invention. The scope of this disclosure is intended to cover such changes. Therefore, the above description of embodiments of the invention is not intended to be limiting. Rather, any limitations on embodiments of the invention are set forth in the appended claims.

Claims

1. A method for measuring overlay, the method comprising: Receive images of the bonded wafers; The outline of the bonded wafer is generated based on the image; as well as This profile is used to adjust the objective lens of an infrared (IR) system based on a single-focus image to perform overlay measurements on the bonded wafer.

2. The method as described in claim 1, wherein, The profile includes the morphology of the bonded wafer, and wherein adjusting the objective lens includes: The objective lens is adjusted along the morphology of the bonded wafer to perform the overlay measurement on the bonded wafer.

3. The method as described in claim 2, wherein, The morphology of the bonded wafer is determined without the need for vertical scanning of the bonded wafer.

4. The method of claim 1, wherein, Generating this contour includes: Scan at least the low spatial frequency components of the warp of the bonded wafer; and The warped low spatial frequency component is mapped onto the image of the bonded wafer to generate the profile.

5. The method of claim 1, wherein, Adjusting the objective lens includes: Based on the profile, adjust the objective lens to a position with a predefined focal length from the bonded wafer; and In response to adjusting the objective lens, at least one image of the bonded wafer at that location is obtained using the objective lens.

6. The method of claim 1, wherein, The bonding wafer includes a first wafer and a second wafer interconnected, and the overlay measurement includes overlay markings between the first wafer and the second wafer.

7. The method of claim 1, further comprising: Receive the second image of the second bonded wafer; as well as The profile is used to adjust the objective lens to perform the overlay measurement on the second bonded wafer.

8. The method of claim 7, wherein, The variation between the first morphology of the bonded wafer and the second morphology of the second bonded wafer is within a predefined range.

9. The method of claim 1, further comprising: In response to the generation of the profile, the profile of the bonded wafer is stored in a lookup table.

10. The method of claim 1, wherein, Receiving an image of the bonded wafer includes scanning at least one of the x-axis or y-axis of the bonded wafer to generate the image.

11. A measurement system comprising: At least one processor, wherein the at least one processor is configured to: Receive images of the bonded wafers; The outline of the bonded wafer is generated based on the image; as well as This profile is used to adjust the objective lens of an infrared (IR) system based on a single-focus image to perform overlay measurements on the bonded wafer.

12. The measurement system of claim 11, wherein, The profile includes the morphology of the bonded wafer, and wherein, in order to adjust the objective lens, the measurement system is configured as follows: The objective lens is adjusted along the morphology of the bonded wafer to perform the overlay measurement on the bonded wafer.

13. The measurement system of claim 12, wherein, The morphology of the bonded wafer is determined without the need for vertical scanning of the bonded wafer.

14. The measurement system of claim 11, wherein, To generate the contour, the at least one processor is configured as follows: Scan at least the low spatial frequency components of the warp of the bonded wafer; and The warped low spatial frequency component is mapped onto the image of the bonded wafer to generate the profile.

15. The measurement system of claim 11, wherein, In order to adjust the objective lens, the at least one processor is configured to: Based on the profile, adjust the objective lens to a position with a predefined focal length from the bonded wafer; and In response to adjusting the objective lens, at least one image of the bonded wafer at that location is obtained using the objective lens.

16. An apparatus comprising: The inspection system includes at least one processor, which is configured to: Receive images of the bonded wafers; The outline of the bonded wafer is generated based on the image; and An infrared (IR) system based on a single-focus image, comprising an objective lens and configured as follows: Use this profile to adjust the objective lens to perform overlay measurements on the bonded wafer.

17. The apparatus of claim 16, wherein, The bonding wafer includes a first wafer and a second wafer interconnected, and the overlay measurement includes overlay markings between the first wafer and the second wafer.

18. The apparatus of claim 16, wherein: The at least one processor is further configured as follows: Receive the second image of the second bonded wafer; and This single-focus IR system is further configured as follows: The profile is used to adjust the objective lens to perform the overlay measurement on the second bonded wafer.

19. The apparatus of claim 18, wherein, The variation between the first morphology of the bonded wafer and the second morphology of the second bonded wafer is within a predefined range.

20. The apparatus of claim 16, further comprising: A storage device configured to store the profile of the bonded wafer in a lookup table in response to the generation of the profile.

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