Measurement pattern and method for measuring overlay displacement of bonded wafer

Abstract

A measurement pattern for monitoring overlay displacement of bonded wafers, the bonded wafers including a top wafer pattern and a bottom wafer pattern. The top wafer pattern includes a first portion having a width Wx1 measured along a first axis. The bottom wafer pattern includes a first feature having a width Wx2 measured along the first axis, wherein the first portion of the top wafer pattern is spaced apart from the first feature of the bottom wafer pattern by a target distance Dx, and wherein the measurement pattern satisfies the following measurement equations: Tx > Dx - Sx; Tx < Dx - Sx + Wx2; Tx > Sx; Tx < Sx + Wx1; and Tx < Dx + Wx1 + Wx2.

Description

Technical Field

[0001] This disclosure relates to a measurement pattern and a method for measuring the stacking displacement of bonded wafers. Background Technology

[0002] Improvements in wafer-to-wafer bonding are becoming increasingly important in 3DIC (three-dimensional integrated circuit) structures. For example, wafer bonding has been used to provide higher integration density by forming vertical stacks of semiconductor components without the need for intermediate structures such as substrates or circuit boards. Currently, semiconductor processes used to monitor wafer bonding misalignment typically rely on visual inspection to determine bonding accuracy. However, this method is inaccurate and can be slow. More efficient and time-saving methods have been proposed to improve the control of overlay shifting. Summary of the Invention

[0003] This disclosure provides a measurement pattern for monitoring the stacking displacement of bonded wafers, comprising a top wafer pattern and a bottom wafer pattern. The top wafer pattern includes a first portion having a width Wx1 measured along a first axis. The bottom wafer pattern includes a first component having a width Wx2 measured along the first axis, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern are spaced apart by a target distance Dx, and wherein the measurement pattern satisfies the following measurement formula:

[0004] Tx > Dx – Sx;

[0005] Tx <Dx–Sx+Wx2;

[0006] Tx > Sx;

[0007] Tx <Dx–Sx+Wx1;

[0008] Where Tx represents the search distance for finding the endpoint of the first part or the endpoint of the first component using an optical detection device; and

[0009] Sx represents the actual displacement of the first portion of the top wafer pattern along the first axis relative to the target distance Dx.

[0010] This disclosure provides a method for measuring the stacking displacement of bonded wafers, comprising the following steps: A top wafer is provided having a top wafer pattern having a first portion and a second portion, wherein the first portion and the second portion form an inverted L-shaped pattern. A bottom wafer is provided having a bottom wafer pattern having a first part and a second part, wherein the first part and the second part form an L-shaped pattern. The top wafer is bonded to the bottom wafer such that the first portion faces the first part and the second portion faces the second part. The displacement of the first portion of the top wafer pattern relative to the first part of the bottom wafer pattern along a first axis is measured using an optical detection device, wherein the method comprises the following steps: performing a first search based on a search distance Tx and finding a first endpoint of the first part of the bottom wafer pattern by detecting a brightness transition from dark to light in the tested pattern; performing a second search based on the search distance Tx and finding a second endpoint of the first portion of the top wafer pattern by detecting a brightness transition from dark to light in the tested pattern; and calculating the distance between the first endpoint and the second endpoint to determine the displacement of the first portion of the top wafer relative to the first part of the bottom wafer along the first axis.

[0011] This disclosure provides a method for measuring the stacking displacement of bonded wafers, comprising the following steps. A top wafer with a top wafer pattern is bonded to a bottom wafer with a bottom wafer pattern, wherein the top wafer pattern includes a first portion having a width Wx1 measured along a first axis, and the bottom wafer pattern includes a first component having a width Wx2 measured along the first axis; a first search is performed by setting a target distance Dx in an optical inspection device, wherein the target distance Dx represents the distance between the first portion of the top wafer pattern and the first component of the bottom wafer pattern when the bonded wafers are not displaced along the first axis; a search distance Tx is set in the optical inspection device; a first search based on the search distance Tx is performed using the optical inspection device to find a first endpoint of the first component of the bottom wafer pattern; a second search based on the search distance Tx is performed using the optical inspection device to find a second endpoint of the first portion of the top wafer pattern; the distance between the first endpoint and the second endpoint is calculated to obtain the actual distance Dac between the first portion of the top wafer pattern and the first component of the bottom wafer pattern; and the difference between the actual distance Dac and the target distance Dx is confirmed to obtain the actual displacement Sx of the first portion of the top wafer pattern relative to the target distance Dx. Attached Figure Description

[0012] The various aspects of this disclosure will be best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the features are not drawn to scale. In fact, for clarity of discussion, the critical dimensions of the features may be arbitrarily increased or decreased.

[0013] Figure 1 This is a flowchart of a method for measuring the stacking displacement of a bonded wafer according to some exemplary embodiments of the present disclosure.

[0014] Figures 2A to 6D These are schematic cross-sectional and top views of various stages of a method for measuring the stacking displacement of a bonded wafer according to some exemplary embodiments of the present disclosure.

[0015] Figure 7 This is a schematic top view of one stage of a method for measuring the stacking displacement of bonded wafers according to some comparative examples of this disclosure.

[0016] Figure 8 This is a schematic top view of one stage of a method for measuring the stacking displacement of bonded wafers according to some comparative examples of this disclosure.

[0017] Figure 9 This is a schematic top view of a measurement pattern of a bonded wafer according to some exemplary embodiments of the present disclosure.

[0018] Explanation of reference numerals in the attached figures

[0019] 100: Top chip

[0020] 102: Substrate

[0021] 104: Interconnection Layer

[0022] 104A: Dielectric layer

[0023] 104B: Conductive layer

[0024] 106: Insulation layer

[0025] 108: Dielectric material layer

[0026] 110: Top chip pattern

[0027] 110-1: Part One

[0028] 110-M1: Module Part 1

[0029] 110-M2: Module Part Two

[0030] 110-2: Part Two

[0031] 200: Bottom chip

[0032] 202: Substrate

[0033] 208: Dielectric material layer

[0034] 210: Bottom chip pattern

[0035] 210-1: First component

[0036] 210-M1: Module First Component

[0037] 210-M2: Second component of module

[0038] 210-2: Second component

[0039] BK: Block pattern

[0040] DR1: First Direction

[0041] DR2: Second Direction

[0042] DR3: Third-party

[0043] DR4: Fourth Direction

[0044] Dac, Dac2: Actual distance

[0045] Dx, Dy: Target distance

[0046] Ed1: First endpoint

[0047] Ed2: Second Endpoint

[0048] Ed3: Third Endpoint

[0049] Ed4: Fourth Endpoint

[0050] MP: Measurement Pattern

[0051] S10, S20, S21, S22, S23, S30: Steps

[0052] SR1: First Search

[0053] SR2: The Second Search

[0054] SR3: The Third Search

[0055] SR4: The Fourth Search

[0056] STR: Striped pattern

[0057] Sx, Sy: Actual displacement

[0058] Tx: Search distance

[0059] Ted1: First target endpoint

[0060] Ted2: Second target endpoint

[0061] Ted3: Third Target Endpoint

[0062] Ted4: Fourth Target Endpoint

[0063] Wx1, Wx2, Wy1, Wy2: Width Detailed Implementation

[0064] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element symbols are used in the drawings and description to denote the same or similar parts.

[0065] The following disclosure provides numerous different embodiments or examples for implementing various features of the provided subject matter. Specific examples of components and arrangements are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, the following description of a second feature forming on or on a first feature may include embodiments in which the second feature and the first feature are formed in direct contact, and may also include embodiments in which additional features may be formed between the second feature and the first feature such that the second feature and the first feature are not in direct contact. Furthermore, component symbols and / or letters may be reused in various instances of this disclosure. Such reuse is for the purpose of brevity and clarity, and is not intended to indicate relationships between the various embodiments and / or configurations discussed.

[0066] Furthermore, for ease of explanation, this document may use spatially relative terms such as “beneath,” “below,” “lower,” “on,” “over,” “overlying,” “above,” and “upper” to describe the relationship between one component or feature shown in the figures and another component or feature. These spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0067] Figure 1 This is a flowchart of a method for measuring the stacking displacement of a bonded wafer according to some exemplary embodiments of the present disclosure. Figures 2A to 6D These are schematic cross-sectional and top views of various stages of a method for measuring the stacking displacement of a bonded wafer according to some exemplary embodiments of the present disclosure. Figures 2A to 6D The method shown will refer to Figure 1Let me explain.

[0068] refer to Figure 1 Step S10 and as follows Figure 2A The diagram illustrates a top wafer 100 and a bottom wafer 200. In some embodiments, the top wafer 100 includes a substrate 102, an interconnect layer 104, an insulating layer 106, and a dielectric material layer 108. The substrate 102 may be a glass substrate or any other suitable transparent substrate for supporting components located thereon. The interconnect layer 104 is disposed on the substrate 102 and may include a dielectric layer 104A and a conductive layer 104B. For example, the dielectric layer 104A is disposed on the substrate 102, and the conductive layer 104B is disposed on the dielectric layer 104A. Although only one dielectric layer 104A and one conductive layer 104B are shown here, it should be noted that the number of dielectric layers 104A and conductive layers 104B is not limited thereto. In some other embodiments, the interconnect layer 104 has multiple dielectric layers 104A and multiple conductive layers 104B for providing electrical connections between components. In some embodiments, the interconnect layer 104 may be electrically connected to various active components (e.g., transistors, etc.) or passive components (e.g., resistors, capacitors, inductors, etc.) in the top wafer 100 via the conductive layer 104B, or may be used to provide electrical connections to various semiconductor dies or chips (not shown).

[0069] In some embodiments, an insulating layer 106 is disposed on and covers the interconnect layer 104. The insulating layer 106 may include an insulating material such as silicon nitride (SiN). Furthermore, a dielectric material layer 108 is disposed on the insulating layer 106 and may include polymeric materials, such as benzocyclobutene (BCB), or other dielectric materials. Figure 2A As shown, the dielectric material layer 108 includes a top wafer pattern 110. For example, the top wafer pattern 110 includes a plurality of stripe patterns protruding into the insulating layer 106. That is, the top wafer pattern 110 can be defined by patterning the insulating layer 106 to form a plurality of openings (strip openings or trenches) and forming the dielectric material layer 108 in the openings.

[0070] like Figure 2AAs further shown, in some embodiments, the bottom wafer 200 includes a substrate 202, a dielectric material layer 208, and a bottom wafer pattern 210. The substrate 202 may be a glass substrate or any other suitable transparent substrate for carrying components located thereon. The dielectric material layer 208 is disposed on the substrate 202 and may include polymeric materials, such as benzocyclobutene (BCB), or other dielectric materials. The bottom wafer pattern 210 is disposed on the substrate 202 and covered by the dielectric material layer 208. In some embodiments, the bottom wafer pattern 210 includes a block pattern, and the block pattern is made of a metallic material. Similar to the top wafer 100, the bottom wafer 200 may also include an interconnect layer (not shown) electrically connected to various active components (e.g., transistors, etc.) or passive components (e.g., resistors, capacitors, inductors, etc.) in the bottom wafer 200, or may be used to provide electrical connections to various semiconductor dies or chips (not shown).

[0071] refer to Figure 1 In step S10 and as follows Figure 2B As shown, the top wafer 100 is bonded to the bottom wafer 200. For example, the dielectric material layer 108 of the top wafer 100 is bonded to the dielectric material layer 208 of the bottom wafer 200 via direct bonding or fusion bonding. In some embodiments, in bonded wafers, the top wafer pattern 110 of the top wafer 100 may be aligned with the bottom wafer pattern 210 of the bottom wafer 200 to form a measurement pattern MP, which can be used to evaluate the overlap displacement of the bonded wafers. That is, if there is a positional offset between the top wafer 100 and the bottom wafer 200, the measurement pattern MP can be used to evaluate the amount of displacement of the bonded wafers.

[0072] Figure 2C This is a schematic top view of the measurement pattern MP of a bonded wafer according to an exemplary embodiment of the present disclosure. Figure 2CAs shown, the measurement pattern MP includes a top wafer pattern 110 of a top wafer 100 and a bottom wafer pattern 210 of a bottom wafer 200. In some embodiments, the top wafer pattern 110 includes a first portion 110-1 and a second portion 110-2, wherein the first portion 110-1 and the second portion 110-2 form an inverted L-shaped pattern. Furthermore, the bottom wafer pattern 210 includes a first portion 210-1 and a second portion 210-2, wherein the first portion 210-1 and the second portion 210-2 form an L-shaped pattern. In an exemplary embodiment, the top wafer 100 is bonded to the bottom wafer 200 such that the first portion 110-1 of the top wafer pattern 110 faces the first portion 210-1 of the bottom wafer pattern 210, and the second portion 110-2 of the top wafer pattern 110 faces the second portion 210-2 of the bottom wafer pattern 210.

[0073] In an exemplary embodiment, the top wafer pattern 110 (including first portions 110-1 and second portions 110-2) includes a plurality of stripe patterns STR, while the bottom wafer pattern 210 (including first portions 210-1 and second portions 210-2) includes a block pattern BK. However, this disclosure is not limited thereto. In some alternative embodiments, one of the top wafer pattern 110 and the bottom wafer pattern 210 includes a plurality of stripe patterns STR, and the other of the top wafer pattern 110 and the bottom wafer pattern 210 includes a block pattern BK. In some other embodiments, the top wafer pattern 110 and the bottom wafer pattern 210 each include a plurality of stripe patterns STR. In yet another embodiment, the top wafer pattern 110 and the bottom wafer pattern 210 each include a block pattern BK.

[0074] Based on the different embodiments described above, it is worth noting that the design of the top wafer pattern 110 and the bottom wafer pattern 210 is not particularly limited, as long as the pattern can be optically measured using an automatic optical inspection (AOI) device. Furthermore, it should be noted that the top wafer pattern 110 and the bottom wafer pattern 210 can be either a striped pattern STR or a block pattern BK, depending on the material used to form the pattern. For example, when the top wafer pattern 110 or the bottom wafer pattern 210 is a dielectric material pattern (or a polymer material pattern), the top wafer pattern 110 / bottom wafer pattern 210 will include a striped pattern STR so that the pattern can be optically measured. On the other hand, when the dielectric material pattern (or polymer material pattern) is not formed into stripes, optical measurement of the dielectric material pattern will be difficult. Additionally, in some embodiments, when the top wafer pattern 110 or the bottom wafer pattern 210 is a metallic material pattern, the top wafer pattern 110 / bottom wafer pattern 210 may include a block pattern BK that can be directly measured using an automatic optical inspection (AOI) device.

[0075] like Figure 2C Further, in some embodiments, a first portion 110-1 of the top wafer pattern 110 has a width Wx1 measured along a first axis (X-axis), while a second portion 110-2 of the top wafer pattern 110 has a width Wy1 measured along a second axis (Y-axis). In some embodiments, a first portion 210-1 of the bottom wafer pattern 210 has a width Wx2 measured along the first axis (X-axis), while a second portion 210-2 of the bottom wafer pattern 210 has a width Wy2 measured along the second axis (Y-axis). Width Wx1 may be greater than width Wx2, and width Wy1 may be greater than width Wy2. In some embodiments, when the top wafer 100 is bonded to the bottom wafer 200 without overlap displacement, the first portion 110-1 of the top wafer pattern 110 and the first portion 210-1 of the bottom wafer pattern 210 will be spaced apart by a target distance Dx. Furthermore, the second portion 110-2 of the top wafer pattern 110 and the second portion 210-2 of the bottom wafer pattern 210 will be spaced apart by a target distance Dy.

[0076] Furthermore, when measuring the displacement of the first portion 110-1 of the top wafer 100 relative to the first component 210-1 of the bottom wafer 200 along the first axis (X-axis) using an optical inspection device, such as an automated optical inspection device capable of automatically measuring the optical patterns of the top wafer pattern 110 and the bottom wafer pattern 210, the automated optical inspection device will satisfy the following measurement formula for measuring the overlapping displacement of the bonded wafers:

[0077] Tx > Dx – Sx;

[0078] Tx <Dx–Sx+Wx2;

[0079] Tx > Sx;

[0080] Tx <Dx–Sx+Wx1;

[0081] Wherein, Tx represents the search distance (searching torrance setting) used by the automated optical inspection device to locate the endpoints of the first portion 110-1 of the top wafer pattern 110 or the first component 210-1 of the bottom wafer pattern 210; and

[0082] Sx represents the actual displacement of the first portion 110-1 of the top wafer pattern 110 relative to the target distance Dx along the first axis (X-axis).

[0083] Similarly, when using an automated optical inspection device to measure the displacement of the second portion 110-2 of the top wafer 100 relative to the second part 210-2 of the bottom wafer 200 along the second axis (Y-axis), the automated optical inspection device satisfies the following measurement formula for measuring the stacking displacement of the bonded wafers:

[0084] Ty>Dy–Sy;

[0085] Ty <Dy–Sy+Wy2;

[0086] Ty>Sy;

[0087] Ty <Dy–Sy+Wy1;

[0088] Where Ty represents the search distance for finding the endpoint of the second portion 110-2 of the top wafer pattern 110 or the endpoint of the second component 210-2 of the bottom wafer pattern 210 using an automated optical inspection device; and

[0089] Sy represents the actual displacement of the second part 110-2 of the top wafer pattern 110 relative to the target distance Dy along the second axis (Y-axis).

[0090] Reference Figures 3A to 6D This describes a detailed method for measuring the stacking displacement of bonded wafers. (Reference) Figure 1 In step S20 and as follows Figures 3A to 4D As shown, the first measurement is performed by using an automated optical inspection device to measure the displacement of the first portion 110-1 of the top wafer 100 relative to the first part 210-1 of the bottom wafer 200 along the first axis (X-axis).

[0091] For example, refer to Figure 3ADuring the first measurement, a target distance Dx is set in the automated optical inspection device. This target distance Dx is the distance that separates the first portion 110-1 of the top wafer pattern 110 from the first component 210-1 of the bottom wafer pattern 210 when there is no displacement along the first axis (X-axis) in the bonded wafer. In an exemplary embodiment, the target distance Dx is set using a standard module having a first portion 110-M1 and a first component 210-M1, which are positioned at locations corresponding to the first portion 110-1 and the first component 210-1 without any overlap displacement.

[0092] refer to Figure 3B Using a standard module having a first part 110-M1 and a first component 210-M1 as a reference, a first target endpoint Ted1 and a second target endpoint Ted2 can be set in an automated optical inspection device. For example... Figure 3B As shown, the first target endpoint Ted1 and the second target endpoint Ted2 correspond to the relative positions (at the edges) of the first part 210-1 of the bottom wafer 200 and the first part 110-1 of the top wafer 100 when the bonding wafer has no displacement.

[0093] refer to Figure 4A After setting the target distance Dx, the first target endpoint Ted1, and the second target endpoint Ted2 in the automated optical inspection device, the bonding wafer can be provided to the automated optical inspection device. Then, the actual displacement Sx of the measurement pattern MP having the first portion 110-1 and the first component 210-1 in the bonding wafer can be measured. In an exemplary embodiment, in the bonding wafer, the first component 210-1 of the bottom wafer pattern 210 is aligned with the first component 210-M1 of the standard module, such that any displacement of the first portion 110-1 of the top wafer pattern 110 relative to the second target endpoint Ted2 can be determined. That is, the position of the first component 210-1 of the bottom wafer 200 is fixed according to the standard module to observe the displacement of the top wafer 100. However, this disclosure is not limited to this. In another embodiment, the position of the first portion 110-1 of the top wafer 100 is fixed according to the standard module to observe the displacement of the bottom wafer 200. That is, the displacement of the bonding wafer can be achieved by fixing the position of either the top wafer pattern 110 or the bottom wafer pattern 210 according to the standard module and observing the displacement of the other.

[0094] refer to Figure 1In step S21, and as shown in Figure 4B, a first search SR1 is performed based on a search distance Tx to locate the first endpoint Ed1 of the first component 210-1 of the bottom wafer pattern 210 by detecting the brightness transition from dark to bright in the pattern under test. The search distance Tx can be preset in the automated optical inspection apparatus. In some embodiments, the first search SR1 is performed with the first target endpoint Ted1 as the search center point, and the search distance Tx is used to perform a search from positive to negative values. For example, in one embodiment, if the search distance Tx in the automated optical inspection apparatus is set to 126 μm, the search is performed with the first target endpoint Ted1 as the search center point within + / - 126 μm.

[0095] Furthermore, in an exemplary embodiment, the first search for SR1 is performed by an automated optical inspection device scanning along a first direction DR1 of the first axis (X-axis) to detect a brightness transition from dark to light. In the automated optical inspection device, a light pattern is observed when the device scans through the top wafer pattern 110 and the bottom wafer pattern 210, and a dark pattern is observed when the device scans through areas other than the top wafer pattern 110 and the bottom wafer pattern 210. Therefore, during the initial search for SR1, a light pattern is observed because the scan passes through the area of ​​the first portion 110-1. Subsequently, a dark pattern, a light pattern, and another dark pattern are observed successively during the first search for SR1. In the exemplary embodiment, when the first "dark to light" brightness transition is observed, the first endpoint Ed1 is found. On the other hand, if the first observed brightness transition is "light to dark," the automated optical inspection device determines that the brightness transition is not the expected "endpoint" and continues scanning along the first direction DR1 to find the first "dark to light" transition.

[0096] refer to Figure 1 In step S22, and as Figure 4C As shown, after obtaining the first endpoint Ed1, a second search SR2 is performed at the same search distance Tx to locate the second endpoint Ed2 of the first portion 110-1 of the top wafer pattern 110 by detecting the brightness transition from dark to bright in the tested pattern. In some embodiments, the second search SR2 uses the second target endpoint Ted2 as the search center point and performs a search from negative to positive values ​​at a search distance Tx. Furthermore, the second search SR2 utilizes an automated optical inspection device to scan along the second direction DR2 of the first axis (X-axis) to detect the first brightness transition from dark to bright, wherein the second direction DR2 is opposite to the first direction DR1.

[0097] In an exemplary embodiment, during the start of the second search SR2, a dark pattern will be observed because the scan passes over the area excluding the top wafer pattern 110 and the bottom wafer pattern 210. Subsequently, during the second search SR2, both bright and dark patterns will be observed, and the first "dark-to-bright" brightness transition will be identified as the second endpoint Ed2.

[0098] refer to Figure 1 In step S23, and as Figure 4D As shown, in subsequent steps, the distance between the first endpoint Ed1 and the second endpoint Ed2 is calculated to determine the displacement of the first portion 110-1 of the top wafer 100 relative to the first component 210-1 of the bottom wafer 200 along the first axis (X-axis). For example, in some embodiments, the distance between the first endpoint Ed1 and the second endpoint Ed2 is calculated to obtain the actual distance Dac between the first portion 110-1 of the top wafer pattern 110 and the first component 210-1 of the bottom wafer pattern 210. Next, the difference between the actual distance Dac and the target distance Dx is confirmed to obtain the actual displacement Sx of the first portion 110-1 of the top wafer pattern 110 relative to the target distance Dx.

[0099] In some embodiments, the automated optical inspection device calculates the actual distance Dac by calculating the number of pixels between the first endpoint Ed1 and the second endpoint Ed2, and the exact distance can be determined by knowing the pixel size. In some embodiments, after confirming the actual displacement Sx, the automated optical inspection device reports the actual displacement Sx (along the X-axis) to a statistical process control (SPC) system to control the post-wafer bonding process.

[0100] refer to Figure 1 In step S30, and as Figures 5A to 6D As shown, the displacement of the second part 110-2 of the top wafer 100 relative to the second part 210-2 of the bottom wafer 200 along the second axis (Y-axis) is measured by performing a second measurement using an automated optical inspection device.

[0101] For example, refer to Figure 5AIn the second measurement, a target distance Dy is set in the automated optical inspection device. This target distance Dy is the distance that separates the second portion 110-2 of the top wafer pattern 110 from the second component 210-2 of the bottom wafer pattern 210 when there is no displacement along the first axis (X-axis) in the bonded wafer. In an exemplary embodiment, the target distance Dy is set using a standard module having a second portion 110-M2 and a second component 210-M2, placed at positions corresponding to the second portion 110-2 and the second component 210-2 when there is no overlap displacement. The target distance Dy may be the same as or different from the target distance Dx and can be adjusted according to design requirements.

[0102] refer to Figure 5B Using a standard module having module second part 110-M2 and module second component 210-M2 as a reference, the third target endpoint Ted3 and the fourth target endpoint Ted4 can be set in the automatic optical inspection device. For example... Figure 5B As shown, the third target endpoint Ted3 and the fourth target endpoint Ted4 correspond to the relative positions (at the edges) of the second part 210-2 of the bottom wafer 200 and the second part 110-2 of the top wafer 100 when the bonding wafer has no displacement.

[0103] refer to Figure 6A After setting the target distance Dy, the third target endpoint Ted3, and the fourth target endpoint Ted4 in the automated optical inspection device, the actual displacement Sy of the measurement pattern MP having the second portion 110-2 and the second component 210-2 in the bonded wafer can be measured. In an exemplary embodiment, in the bonded wafer, the second component 210-2 of the bottom wafer pattern 210 is aligned with the module second component 210-M2 of the standard module, such that any displacement of the second portion 110-2 of the top wafer pattern 110 relative to the fourth target endpoint Ted4 can be determined. That is, the second component 210-2 of the bottom wafer 200 is fixed according to the standard module to observe the displacement of the top wafer 100. However, this disclosure is not limited to this, and the displacement of the bonded wafer can be determined by fixing the position of either the top wafer pattern 110 or the bottom wafer pattern 210 according to the standard module and observing the displacement of the other.

[0104] refer to Figure 6BIn subsequent steps, a third search SR3 is performed based on the search distance Ty to locate the third endpoint Ed3 of the second component 210-2 of the bottom wafer pattern 210 by detecting the brightness transition from dark to bright in the tested pattern. The search distance Ty can be preset in an automated optical inspection device and can be different from or the same as the search distance Tx depending on the actual size of the top wafer pattern 110 and the bottom wafer pattern 210. In some embodiments, the third search SR3 uses the third target endpoint Ted3 as the search center point and searches for positive to negative values ​​using the search distance Ty.

[0105] Furthermore, in an exemplary embodiment, the third search SR3 is performed using an automated optical detection device to scan along a third direction DR3 on the second axis (Y-axis) to detect a brightness transition from dark to bright. For example, during the start of the third search SR3, a bright pattern will be observed since the area of ​​the second portion 110-2 is being scanned. Subsequently, during the third search SR3, a dark pattern, a bright pattern, and another dark pattern will be observed successively, and the first "dark to bright" brightness transition will be identified as the third endpoint Ed3.

[0106] refer to Figure 6C After obtaining the third endpoint Ed3, a fourth search SR4 is performed at the same search distance Ty to locate the fourth endpoint Ed4 of the second portion 110-2 of the top wafer pattern 110 by detecting the brightness transition from dark to bright in the tested pattern. In some embodiments, the fourth search SR4 uses the fourth target endpoint Ted4 as the search center point and searches from positive to negative values ​​at a search distance Ty. Furthermore, the fourth search SR4 utilizes an automated optical inspection device to scan along the fourth direction DR4 of the second axis (Y-axis) to detect the first brightness transition from dark to bright, wherein the fourth direction DR4 is opposite to the third direction DR3.

[0107] In an exemplary embodiment, during the start of the fourth search SR4, a dark pattern will be observed because the scan passes over the area excluding the top wafer pattern 110 and the bottom wafer pattern 210. Subsequently, bright and dark patterns will be observed consecutively during the fourth search SR4, and the first "dark-to-light" brightness transition will be identified as the fourth endpoint Ed4.

[0108] refer to Figure 6DIn a subsequent step, the distance between the third endpoint Ed3 and the fourth endpoint Ed4 is calculated to determine the displacement of the second portion 110-2 of the top wafer 100 relative to the second part 210-2 of the bottom wafer 200 along the second axis (Y-axis). For example, in some embodiments, the distance between the third endpoint Ed3 and the fourth endpoint Ed4 is calculated to obtain the actual distance Dac2 between the second portion 110-2 of the top wafer pattern 110 and the second part 210-2 of the bottom wafer pattern 210. Next, the difference between the actual distance Dac2 and the target distance Dy is confirmed to obtain the actual displacement Sy of the second portion 110-2 of the top wafer pattern 110 relative to the target distance Dy.

[0109] In some embodiments, the automated optical inspection device calculates the actual distance Dac2 by calculating the number of pixels between the third endpoint Ed3 and the fourth endpoint Ed4, and the exact distance can be determined by knowing the pixel size. In some embodiments, after determining the actual displacement Sy, the automated optical inspection device reports the actual displacement Sy (along the Y-axis) to a statistical process control (SPC) system to control the post-wafer bonding process. This completes the method for measuring the stacking displacement of bonded wafers according to some exemplary embodiments of this disclosure.

[0110] As mentioned above, the automated optical inspection device measures the stacking displacement of the bonded wafers according to a specific measurement formula; otherwise, the measurement will be inaccurate. (Refer to...) Figure 7 and Figure 8 This section provides an example illustrating the derivation of measurement formulas.

[0111] Figure 7 This is a schematic top view of one stage of a method for measuring the stacking displacement of bonded wafers according to some comparative examples of this disclosure. For example, it is according to the above... Figure 4B and Figure 4C The steps described herein shall be performed in accordance with the method. Figure 7 The comparative examples will explain why the measurement formulas Tx>Dx-Sx (search distance > target distance - actual displacement) and Tx>Sx (search distance > actual displacement) need to be satisfied.

[0112] like Figure 7 As shown, in some embodiments, when the search distance Tx is set to be less than the distance difference (Dx-Sx) between the target distance Dx and the actual displacement Sx, and when the search distance Tx is set to be less than the actual displacement Sx, the overlapping displacement cannot be accurately measured. For example, as Figure 7As shown, although the first endpoint Ed1 can be accurately found in the first search SR1, it can be seen that no endpoint can be found in the second search SR2. The reason is that the starting point of the second search SR2 (search distance is Tx) is located at a position overlapping with the first part 110-1 of the top wafer pattern 110. Therefore, the "dark to bright" luminance conversion cannot be observed, and the actual displacement amount Sx cannot be correctly confirmed.

[0113] Therefore, when considering the first search SR1 and the second search SR2, the measurement formula along the first axis (X-axis) should satisfy the following relationships: Tx > Dx - Sx (search distance > target distance - actual displacement amount) and Tx > Sx (search distance > actual displacement amount). Similarly, the measurement formula along the second axis (Y-axis) should satisfy the following relationships: Ty > Dy - Sy (search distance > target distance - actual displacement amount) and Ty > Sy (search distance > actual displacement amount).

[0114] Figure 8 is a schematic top view of one stage in a method for measuring the stack displacement of bonded wafers according to some comparative examples of the present disclosure. For example, according to the above Figure 4B with Figure 4C the method is performed according to the steps described. Figure 8 The comparative example of

[0115] As Figure 8 shown, in some embodiments, when the search distance Tx is set to be greater than Dx - Sx + Wx2 and greater than Dx - Sx + Wx1, the stack displacement amount cannot be accurately measured. For example, as Figure 8 shown, although the second endpoint Ed1 can be accurately found in the second search SR2, it can be seen that the first search SR1 cannot correctly confirm the first endpoint Ed1-1 of the first part 210. The reason is that the search distance Tx is too large, and the first search SR1 will erroneously determine the first "dark to bright" luminance conversion as the first endpoint Ed1. Therefore, the actual displacement amount Sx cannot be correctly calculated.

[0116] Therefore, when considering the first search SR1 and the second search SR2, the measurement formula along the first axis (X-axis) should also satisfy the following relationships: Tx < Dx – Sx + Wx2 (search distance < target distance – actual displacement + width Wx2 of the first component 210-1) and Tx < Dx - Sx + Wx1 (search distance < target distance - actual displacement + width Wx1 of the first part 110-1). Similarly, the measurement formula along the second axis (Y-axis) should satisfy the following relationships: Ty < Dy - Sy + Wy2 (search distance < target distance - actual displacement + width Wy2 of the second component 210-2) and Ty < Dy - Sy + Wy1 (search distance < target distance - actual displacement + width Wy1 of the second part 110-2).

[0117] By understanding the following measurement formula along the first axis (X-axis):

[0118] Tx > Dx – Sx;

[0119] Tx < Dx – Sx + Wx2;

[0120] Tx > Sx;

[0121] Tx < Dx – Sx + Wx1;

[0122] The measurement formula expressed by the following relationships can be further derived:

[0123] Sx > Dx – Tx;

[0124] Sx < Dx – Tx + Wx2;

[0125] Sx < Tx;

[0126] Sx < Dx – Tx + Wx1.

[0127] Similarly, by understanding the following measurement formula along the second axis (Y-axis):

[0128] Ty > Dy – Sy;

[0129] Ty < Dy – Sy + Wy2;

[0130] TY > SY;

[0131] Ty < Dy – Sy + Wy1;

[0132] The measurement formula expressed by the following relationships can be further derived:

[0133] Sy > Dy – Ty;

[0134] Sy < Dy – Ty + Wy2;

[0135] SY < TY;

[0136] Sy <Dy–Ty+Wy1。

[0137] Figure 9 This is a schematic top view of a measurement pattern for a bonded wafer according to some exemplary embodiments of the present disclosure. In an exemplary embodiment, the target distance Dx between the first portion 110-1 and the first component 210-1 is set to 150 μm, the width Wx1 of the first portion 110-1 is set to 100 μm, and the width Wx2 of the first component 210-1 is set to 50 μm. In this case, when the measurement formula is known in advance, the relationship between the search distance Tx and the actual displacement Sx should satisfy the following:

[0138] (1) Tx+Sx<250μm(Dx+Wx1);

[0139] (2) Tx < 200 μm (Dx + Wx2);

[0140] (3) Tx>Sx (Tx is greater than 125μm and Sx is less than 125μm).

[0141] Therefore, when the search distance Tx is set to + / -126 μm, the maximum measurable actual displacement Sx is calculated to be + / -124 μm (250 μm – 126 μm). Similarly, the maximum measurable actual displacement Sx can be changed according to the search distance Tx. For example, when the search distance Tx is set to + / -130 μm, the maximum measurable actual displacement Sx is calculated to be + / -120 μm (250 μm – 130 μm), and when the search distance Tx is set to + / -160 μm, the maximum measurable actual displacement Sx is calculated to be + / -90 μm (250 μm – 160 μm). Furthermore, the search distance Tx and the actual displacement Sx can be appropriately controlled by changing the target distance Dx and the widths Wx1 and Wx2. The same measurement formula also applies when measuring along different axes.

[0142] Based on the above, it should be understood that the design and dimensions of the top wafer pattern 110 and the bottom wafer pattern 210 can be appropriately adjusted. Furthermore, by adjusting the target distance Dx, the widths of the top wafer pattern 110 and the bottom wafer pattern 210 along the first and second axes (Wx1, Wx2, Wy1, and Wy2), the search distance Tx and the actual displacement Sx can be controlled to meet different measurement conditions and different product requirements.

[0143] In the above embodiments, the measurement patterns, including top and bottom wafer patterns, can be used to monitor the overlap displacement of the bonded wafers. An automated optical inspection device can be used to monitor the bonded wafers, which helps to automatically report the actual displacement of the measurement patterns to the statistical process control (SPC) system. This method is highly efficient and prevents human error in judging overlap displacement by visual inspection. Overall, it achieves a high-volume measurement method that will replace traditional methods based on visual inspection. The overlap displacement of bonded wafers can also be measured in large quantities while ensuring the quality of the measurements.

[0144] According to some embodiments of this disclosure, a measurement pattern for monitoring the stacking displacement of bonded wafers includes a top wafer pattern and a bottom wafer pattern. The top wafer pattern includes a first portion having a width Wx1 measured along a first axis. The bottom wafer pattern includes a first component having a width Wx2 measured along the first axis, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern are spaced apart by a target distance Dx, and wherein the measurement pattern satisfies the following measurement formula:

[0145] Tx > Dx – Sx;

[0146] Tx <Dx–Sx+Wx2;

[0147] Tx > Sx;

[0148] Tx <Dx–Sx+Wx1;

[0149] Where Tx represents the search distance for finding the endpoint of the first part or the endpoint of the first component using an optical detection device; and

[0150] Sx represents the actual displacement of the first portion of the top wafer pattern along the first axis relative to the target distance Dx.

[0151] In some embodiments, the plurality of stripe patterns are dielectric material patterns, and the block pattern is a metallic material pattern. In some embodiments, a first portion of the top wafer pattern and a first component of the bottom wafer pattern each include a plurality of stripe patterns.

[0152] According to some other embodiments of the present disclosure, a method for measuring the displacement of a stacked pair of bonded wafers includes the following steps. Provide a top wafer having a top wafer pattern, the top wafer pattern having a first portion and a second portion, and wherein the first portion and the second portion form an inverted L-shaped pattern. Provide a bottom wafer having a bottom wafer pattern, the bottom wafer pattern having a first component and a second component, and wherein the first component and the second component form an L-shaped pattern. Bond the top wafer to the bottom wafer such that the first portion faces the first component and the second portion faces the second component. Measure the displacement of the first portion of the top wafer pattern relative to the first component of the bottom wafer pattern along a first axis by using an optical detection device, wherein the method includes the following steps: perform a first search based on a search distance Tx, and find the first end point of the first component of the bottom wafer pattern by detecting the brightness transition of the measured pattern from dark to bright; perform a second search based on the search distance Tx, and find the second end point of the first portion of the top wafer pattern by detecting the brightness transition of the measured pattern from dark to bright; and calculate the distance between the first end point and the second end point to determine the displacement of the first portion of the top wafer relative to the first component of the bottom wafer along the first axis.

[0153] In some embodiments, the optical detection device satisfies the following measurement formula for measuring the displacement of a stacked pair of bonded wafers: Tx > Dx – Sx; Tx < Dx – Sx + Wx2; Tx > Sx; Tx < Dx – Sx + Wx1; where Dx represents the target distance that separates the first portion of the top wafer pattern from the first component of the bottom wafer pattern when there is no displacement of the bonded wafers along the first axis; Sx represents the actual displacement amount of the first portion of the top wafer pattern along the first axis relative to the target distance Dx; Wx1 represents the width measured along the first axis of the first portion; and Wx2 represents the width measured along the first axis of the first component. In some embodiments, one of the first portion of the top wafer pattern and the first component of the bottom wafer pattern includes a plurality of stripe patterns, and the other of the first portion of the top wafer pattern and the first component of the bottom wafer pattern includes a block pattern. In some embodiments, the method further includes: measuring the displacement of the second portion of the top wafer pattern relative to the second component of the bottom wafer pattern along a second axis by using the optical detection device, which includes: performing a third search based on a search distance Ty, and finding the third end point of the second component of the bottom wafer pattern by detecting the brightness transition of the measured pattern from dark to bright; performing a fourth search based on the search distance Ty, and finding the fourth end point of the second portion of the top wafer pattern by detecting the brightness transition of the measured pattern from dark to bright; and calculating the distance between the third end point and the fourth end point to determine the displacement of the second portion of the top wafer relative to the second component of the bottom wafer along the second axis.

[0154] According to another embodiment of the present disclosure, a method for measuring the stacking displacement of a bonded wafer includes the following steps. A top wafer with a top wafer pattern is bonded to a bottom wafer with a bottom wafer pattern, wherein the top wafer pattern includes a first portion having a width Wx1 measured along a first axis, and the bottom wafer pattern includes a first component having a width Wx2 measured along the first axis; a first search is performed by setting a target distance Dx in an optical inspection device, wherein the target distance Dx represents the distance between the first portion of the top wafer pattern and the first component of the bottom wafer pattern when the bonded wafers are not displaced along the first axis; a search distance Tx is set in the optical inspection device; a first search based on the search distance Tx is performed using the optical inspection device to find a first endpoint of the first component of the bottom wafer pattern; a second search based on the search distance Tx is performed using the optical inspection device to find a second endpoint of the first portion of the top wafer pattern; the distance between the first endpoint and the second endpoint is calculated to obtain the actual distance Dac between the first portion of the top wafer pattern and the first component of the bottom wafer pattern; and the difference between the actual distance Dac and the target distance Dx is confirmed to obtain the actual displacement Sx of the first portion of the top wafer pattern relative to the target distance Dx.

[0155] In some embodiments, the optical detection device satisfies the following measurement formula for measuring the displacement of the stacked pair of bonded wafers: Tx > Dx – Sx; Tx < Dx – Sx + Wx2; Tx > Sx; Tx < Dx – Sx + Wx1. In some embodiments, one of the first part of the top wafer pattern and the first component of the bottom wafer pattern includes a plurality of stripe patterns, and the other of the first part of the top wafer pattern and the first component of the bottom wafer pattern includes a block pattern. In some embodiments, the first part of the top wafer pattern and the first component of the bottom wafer pattern each include a plurality of stripe patterns. In some embodiments, the first part of the top wafer pattern and the first component of the bottom wafer pattern each include a block pattern. In some embodiments, the top wafer pattern further includes a second part having a width Wy1 measured along a second axis, and the bottom wafer pattern further includes a second component having a width Wy2 measured along the second axis, and the method further includes: performing a second search by: setting a target distance Dy in the optical detection device, where the target distance Dy represents the distance by which the second part of the top wafer pattern is spaced apart from the second component of the bottom wafer pattern when the bonded wafers have no displacement along the second axis; setting a search distance Ty in the optical detection device; using the optical detection device to perform a third search according to the search distance Ty to find a third endpoint of the second component of the bottom wafer pattern; using the optical detection device to perform a fourth search according to the search distance Ty to find a fourth endpoint of the second part of the top wafer pattern; calculating the distance between the third endpoint and the fourth endpoint to obtain an actual distance Dac2 between the second part of the top wafer pattern and the second component of the bottom wafer pattern; and confirming the difference between the actual distance Dac2 and the target distance Dy to obtain an actual displacement amount Sy of the second part of the top wafer pattern relative to the target distance Dy.

[0156] The features of several embodiments are outlined above so that those skilled in the art can better understand various aspects of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or realize the same advantages as the embodiments described herein. Those skilled in the art should also recognize that these equivalent structures do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A measurement pattern for monitoring the stacking displacement of bonded wafers, comprising: The top wafer pattern includes a first portion having a width Wx1 measured along a first axis; A bottom wafer pattern includes a first component having a width Wx2 measured along a first axis, wherein the first portion of the top wafer pattern is spaced from the first component of the bottom wafer pattern by a target distance Dx, and wherein the measured pattern satisfies the following measurement formula: Tx > Dx – Sx; Tx <Dx–Sx+Wx2; Tx > Sx; Tx <Dx–Sx+Wx1; Where Tx represents the search distance for finding the endpoint of the first part or the endpoint of the first component using an optical detection device; as well as Sx represents the actual displacement of the first portion of the top wafer pattern along the first axis relative to the target distance Dx.

2. The measurement pattern according to claim 1, wherein one of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a plurality of stripe patterns, and the other of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a block pattern.

3. The measuring pattern according to claim 2, wherein the plurality of stripe patterns are dielectric material patterns and the block pattern is a metallic material pattern.

4. The measurement pattern of claim 1, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern each comprise a plurality of stripe patterns.

5. The measurement pattern of claim 1, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern each comprise a block pattern.

6. The measurement pattern according to claim 1, wherein: The top wafer pattern further includes a second portion having a width Wy1 measured along a second axis; The bottom wafer pattern further includes a second component having a width Wy2 measured along the second axis, wherein the second portion of the top wafer pattern is spaced from the second component of the bottom wafer pattern by a target distance Dy, and wherein the measured pattern satisfies the following measurement formula: Ty>Dy–Sy; Ty <Dy–Sy+Wy2; Ty>Sy; Ty <Dy–Sy+Wy1; in, Ty represents the search distance for finding the endpoint of the second part or the endpoint of the second component using the optical detection device; as well as Sy represents the actual displacement of the second portion of the top wafer pattern along the second axis relative to the target distance Dy.

7. The measurement pattern according to claim 6, wherein the first portion and the second portion of the top wafer pattern form an inverted L-shaped pattern, and the first component and the second component of the bottom wafer pattern form an L-shaped pattern.

8. A method for measuring the stacking displacement of bonded wafers, comprising: A top wafer is provided having a top wafer pattern, the top wafer pattern having a first portion and a second portion; A bottom wafer with a bottom wafer pattern is provided, the bottom wafer pattern having a first component and a second component; The top wafer is bonded to the bottom wafer such that the first portion faces the first component and the second portion faces the second component; Measuring the displacement along a first axis of the first portion of the top wafer pattern relative to the first component of the bottom wafer pattern using an optical inspection device includes: The first search is performed based on the search distance Tx, and the first endpoint of the first component of the bottom wafer pattern is found by detecting the brightness transition of the tested pattern from dark to bright. A second search is performed based on the search distance Tx, and the second endpoint of the first part of the top wafer pattern is found by detecting the brightness transition of the tested pattern from dark to bright. as well as Calculate the distance between the first endpoint and the second endpoint to determine the displacement of the first portion of the top wafer relative to the first component of the bottom wafer along the first axis.

9. The method of claim 8, further comprising: Before performing the first and second searches, a first target endpoint and a second target endpoint are set in the optical detection device, wherein the first target endpoint and the second target endpoint correspond to the relative positions of the first component of the bottom wafer and the first portion of the top wafer in the bonding wafer without displacement, and wherein The first search uses the first target endpoint as the search center point and searches for positive to negative values ​​using the search distance Tx; and The second search is performed with the second target endpoint as the search center point, and the search distance Tx is used to search from negative to positive values.

10. The method according to claim 9, wherein, The first search is performed by scanning along the first direction of the first axis using the optical detection device to detect brightness transitions from dark to bright. The second search is performed by scanning along a second direction of the first axis using the optical detection device to detect brightness transitions from dark to bright, wherein the second direction is opposite to the first direction.

11. The method of claim 8, wherein the optical detection device satisfies the following measurement formula for measuring the stacking displacement of the bonded wafers: Tx > Dx – Sx; Tx <Dx–Sx+Wx2; Tx > Sx; Tx <Dx–Sx+Wx1; in, Dx represents the target distance that separates the first portion of the top wafer pattern from the first component of the bottom wafer pattern without displacement along the first axis; Sx represents the actual displacement of the first portion of the top wafer pattern along the first axis relative to the target distance Dx; Wx1 represents the width of the first portion measured along the first axis; Wx2 represents the width of the first component measured along the first axis.

12. The method of claim 8, wherein one of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a plurality of stripe patterns, and the other of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a block pattern.

13. The method of claim 8, further comprising: Measuring the displacement along a second axis of the second portion of the top wafer pattern relative to the second component of the bottom wafer pattern using the optical detection device includes: A third search is performed based on the search distance Ty, and the third endpoint of the second component of the bottom wafer pattern is found by detecting the brightness transition of the tested pattern from dark to bright. A fourth search is performed based on the search distance Ty, and the fourth endpoint of the second portion of the top wafer pattern is located by detecting the brightness transition of the tested pattern from dark to light; and Calculate the distance between the third endpoint and the fourth endpoint to determine the displacement of the second portion of the top wafer relative to the second component of the bottom wafer along the second axis.

14. A method for measuring the stacking displacement of bonded wafers, comprising: A top wafer with a top wafer pattern is bonded to a bottom wafer with a bottom wafer pattern, wherein the top wafer pattern includes a first portion having a width Wx1 measured along a first axis, and the bottom wafer pattern includes a first component having a width Wx2 measured along the first axis. Perform the first search using the following methods: A target distance Dx is set in the optical inspection device, wherein the target distance Dx represents the distance between the first portion of the top wafer pattern and the first component of the bottom wafer pattern when the bonding wafer has no displacement along the first axis; A search distance Tx is set in the optical detection device; The optical detection device is used to perform a first search based on the search distance Tx to locate the first endpoint of the first component of the bottom wafer pattern; The optical detection device is used to perform a second search based on the search distance Tx to locate the second endpoint of the first portion of the top wafer pattern; Calculate the distance between the first endpoint and the second endpoint to obtain the actual distance Dac between the first portion of the top wafer pattern and the first component of the bottom wafer pattern; as well as The difference between the actual distance Dac and the target distance Dx is confirmed to obtain the actual displacement Sx of the first portion of the top wafer pattern relative to the target distance Dx.

15. The method of claim 14, wherein the first endpoint and the second endpoint are found by detecting a brightness transition from dark to bright in the pattern under test using the optical detection device during the first search and the second search.

16. The method of claim 14, wherein the optical detection device satisfies the following measurement formula for measuring the stacking displacement of the bonded wafers: Tx > Dx – Sx; Tx <Dx–Sx+Wx2; Tx > Sx; Tx <Dx–Sx+Wx1。 17. The method of claim 14, wherein one of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a plurality of stripe patterns, and the other of the first portion of the top wafer pattern and the first component of the bottom wafer pattern comprises a block pattern.

18. The method of claim 14, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern each comprise a plurality of stripe patterns.

19. The method of claim 14, wherein the first portion of the top wafer pattern and the first component of the bottom wafer pattern each comprise a block pattern.

20. The method of claim 14, wherein the top wafer pattern further includes a second portion having a width Wy1 measured along a second axis, and the bottom wafer pattern further includes a second component having a width Wy2 measured along the second axis, and the method further includes: The second search can be performed using the following methods: A target distance Dy is set in the optical inspection device, wherein the target distance Dy represents the distance between the second portion of the top wafer pattern and the second component of the bottom wafer pattern when the bonding wafer has no displacement along the second axis; A search distance Ty is set in the optical detection device; The optical detection device is used to perform a third search based on the search distance Ty to locate the third endpoint of the second component of the bottom wafer pattern; The optical detection device is used to perform a fourth search based on the search distance Ty to locate the fourth endpoint of the second portion of the top wafer pattern; Calculate the distance between the third endpoint and the fourth endpoint to obtain the actual distance Dac2 between the second part of the top wafer pattern and the second part of the bottom wafer pattern; as well as The difference between the actual distance Dac2 and the target distance Dy is confirmed to obtain the actual displacement Sy of the second part of the top wafer pattern relative to the target distance Dy.

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