Semiconductor structure and measurement method for measuring wafer bonding strength

Abstract

The present application relates to a semiconductor structure and a measurement method for measuring wafer bonding strength. The measurement method includes the following steps: forming a first measurement channel in a first wafer that penetrates a portion of a first side surface and a portion of a first bonding surface, and forming a second measurement channel in a second wafer that penetrates a portion of a second side surface and a portion of a second bonding surface; bonding the first wafer and the second wafer via a first bonding layer and a second bonding layer, so that the projections of the first measurement channel and the second measurement channel on the first bonding surface overlap; inserting a measuring tool through the first measurement channel and the second measurement channel and between a first target position and a second target position, thereby generating a crack between the first target position and the second target position of the first wafer; measuring the length of the crack, and calculating the bonding strength between the first target position and the second target position of the second wafer based on the length. This method achieves measurement of the bonding strength of the central region of the bonding surface of the bonded wafers.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a semiconductor structure and a measurement method for measuring wafer bonding strength. Background Art

[0002] Wafer bonding technology is a process that tightly combines two or more wafers (usually silicon or other semiconductor materials) through physical or chemical methods. It is widely used in semiconductor manufacturing, microelectromechanical systems (MEMS), optoelectronic devices and three-dimensional integrated chips (3D ICs). Its core purpose is to achieve high-precision integration of multi-layer structures to improve device performance or realize special functions.

[0003] In wafer bonding technology, bond strength is a critical parameter and an important indicator of bonding quality. If the bond strength is low, the two bonded wafers are likely to crack during processing, leading to failure.

[0004] Since testing bond strength is destructive, the industry uses pure silicon wafers with the same thin film composition grown on the surface to simulate the bond strength of real chips. Currently, the industry has existing bond strength testing methods including: crack propagation method, four-point bending method, tensile method, and shear method. Among them, the crack propagation method is the most commonly used. However, the existing crack propagation method is only suitable for measuring the bond strength of the edge area of ​​the bonded wafer, and it is difficult to measure the bond strength of the center area of ​​the bonded wafer. Summary of the Invention

[0005] Based on this, the present application provides a semiconductor structure and a measurement method for measuring wafer bonding strength, so as to measure the bonding strength of the central area of ​​the bonding surface of the bonded wafer or even any position on the bonding surface.

[0006] In a first aspect, an embodiment of the present application provides a method for measuring wafer bonding strength, comprising:

[0007] Providing a first wafer, the first wafer comprising a first side surface and a first bonding surface and a first back surface that are separated from each other;

[0008] Providing a second wafer, the second wafer comprising a second side surface and a second bonding surface and a second back surface that are separated from each other;

[0009] forming a first measurement channel in the first wafer, the first measurement channel penetrating a portion of the first side surface and a portion of the first bonding surface, and extending from the first side surface to a first target position on the first bonding surface;

[0010] forming a second measurement channel in the second wafer, the second measurement channel penetrating a portion of the second side surface and a portion of the second bonding surface, and extending from the second side surface to a second target position on the second bonding surface;

[0011] forming a first bonding layer on the first bonding surface of the first wafer and the first measurement channel;

[0012] forming a second bonding layer on the second bonding surface of the second wafer and the second measurement channel;

[0013] Bonding the first bonding layer and the second bonding layer, so that the projections of the first measurement channel and the second measurement channel on the first bonding surface overlap;

[0014] Providing a measuring tool, controlling the measuring tool to pass through the first measuring channel and the second measuring channel and then be inserted between the first target position and the second target position, so as to generate a crack between the first wafer and the second wafer;

[0015] The length of the crack is measured, and the bonding strength between the first target position and the second target position is obtained based on the length calculation using a crack propagation method.

[0016] In some embodiments of the present application, obtaining the bonding strength at the first target position and the second target position based on the length calculation using the crack propagation method includes: calculating the bonding strength using the following formula:

[0017] Y=(3t b 2 E1E2t w1 3 t w2 3 ) / 16L 4 (E1t w1 3 +E2t w2 3 ),

[0018] Where Y represents the bond strength, t b represents the height of the measuring tool, E1 represents the Young's modulus of the first wafer, E2 represents the Young's modulus of the second wafer, t w1 represents the thickness of the first wafer, t w2 represents the thickness of the second wafer, and L represents the length of the crack.

[0019] In some embodiments of the present application, the length of the crack is measured using an infrared measuring instrument or an ultrasonic measuring instrument.

[0020] In some embodiments of the present application, the first measurement channel is formed in the first wafer and the second measurement channel is formed in the second wafer by using a grinding wheel cutting process.

[0021] In some embodiments of the present application, the sidewall of the first measuring channel facing away from the first side surface is an inclined sidewall; and the sidewall of the second measuring channel facing away from the second side surface is an inclined sidewall.

[0022] In some embodiments of the present application, before forming the first measurement channel in the first wafer, a first protective adhesive is formed on the first bonding surface, and after forming the first measurement channel, the first protective adhesive is removed;

[0023] Before forming the second measurement channel in the second wafer, a second protective adhesive is formed on the second bonding surface, and after forming the second measurement channel, the second protective adhesive is removed.

[0024] In some embodiments of the present application, the number of the first measurement channel and the number of the second measurement channel are both one, and the length and width of the first measurement channel are correspondingly the same as the length and width of the second measurement channel.

[0025] In some embodiments of the present application, the depth of the first measurement channel is 40%-85% of the thickness of the first wafer; the depth of the second measurement channel is 40%-85% of the thickness of the second wafer.

[0026] In some embodiments of the present application, the straight-line distance between the first target position and the center of the first wafer is ≤ 3 / 4 times the first wafer radius; the straight-line distance between the second target position and the center of the second wafer is ≤ 3 / 4 times the second wafer radius.

[0027] In some embodiments of the present application, the depth of the first measurement channel is 350 μm-600 μm, and the width is 2.5 mm-5 mm; the depth of the second measurement channel is 350 μm-600 μm, and the width is 2.5 mm-5 mm.

[0028] In some embodiments of the present application, the first measurement channel extends from the first side surface along the crystal orientation of the first wafer to the first target position; the second measurement channel extends from the second side surface along the crystal orientation of the second wafer to the second target position.

[0029] In some embodiments of the present application, the number of first target positions is multiple, and the number of corresponding first measurement channels is multiple; the number of second target positions is multiple, and the number of corresponding second measurement channels is multiple, the number of second target positions is equal to the number of first target positions, and the number of second measurement channels is equal to the number of first measurement channels; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide.

[0030] In some embodiments of the present application, multiple first target positions are located at different positions on the first bonding surface of the first wafer, and multiple first measurement channels extend from different positions on the first side surface of the first wafer to corresponding first target positions.

[0031] In some embodiments of the present application, multiple second target positions are located at different positions of the second bonding surface of the second wafer, and multiple second measurement channels extend from different positions of the second side surface of the second wafer to corresponding second target positions.

[0032] In some embodiments of the present application, the lengths of the multiple first measurement channels are different, the lengths of the multiple second measurement channels are different, and the lengths of the first measurement channels and the corresponding second measurement channels whose projections overlap on the first bonding surface are the same.

[0033] In some embodiments of the present application, the width of the measuring tool is less than or equal to the width of the first measuring channel and the width of the second measuring channel, the height of the measuring tool is less than or equal to the sum of the depth of the first measuring channel and the depth of the second measuring channel, and the length of the measuring tool is greater than the length of the first measuring channel and the length of the second measuring channel.

[0034] In some embodiments of the present application, the measuring tool includes a blade tip and a blade body connected to the blade tip, the width of the blade tip is equal to the width of the blade body, and the height of the blade tip is less than the height of the blade body; when the measuring tool is inserted between the first target position and the second target position, the blade tip is first inserted between the first target position and the second target position, and then the blade body is inserted between the first target position and the second target position.

[0035] In a second aspect, an embodiment of the present application further provides a semiconductor structure for measuring wafer bonding strength, comprising:

[0036] A first wafer, the first wafer comprising a first side surface and a first bonding surface and a first back surface that are separated from each other;

[0037] a first measurement channel located in the first wafer, the first measurement channel penetrating a portion of the first side surface and a portion of the first bonding surface, and extending from the first side surface to a first target position on the first bonding surface;

[0038] a first bonding layer, located on the first bonding surface of the first wafer and the first measurement channel;

[0039] a second wafer, the second wafer comprising a second side surface and a second bonding surface and a second back surface that are separated from each other;

[0040] a second measurement channel located in the second wafer, the second measurement channel penetrating a portion of the second side surface and a portion of the second bonding surface, and extending from the second side surface to a second target position on the second bonding surface;

[0041] a second bonding layer, located on the second bonding surface of the second wafer and the second measurement channel;

[0042] The first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, and the projections of the first measurement channel and the second measurement channel on the first bonding surface overlap. The first measurement channel and the second measurement channel are used as channels for a measuring tool to pass through when measuring the bonding strength, so that the measuring tool is inserted between the first target position and the second target position after passing through the first measurement channel and the second measurement channel, and a crack is generated between the first wafer at the first target position and the second wafer at the second target position.

[0043] In some embodiments of the present application, the sidewall of the first measuring channel facing away from the first side surface is an inclined sidewall; and the sidewall of the second measuring channel facing away from the second side surface is an inclined sidewall.

[0044] In some embodiments of the present application, the number of the first measurement channel and the number of the second measurement channel are both one, and the length and width of the first measurement channel are correspondingly the same as the length and width of the second measurement channel.

[0045] In some embodiments of the present application, the depth of the first measurement channel is 40%-85% of the thickness of the first wafer; the depth of the second measurement channel is 40%-85% of the thickness of the second wafer.

[0046] In some embodiments of the present application, the straight-line distance between the first target position and the center of the first wafer is ≤ 3 / 4 times the first wafer radius; the straight-line distance between the second target position and the center of the second wafer is ≤ 3 / 4 times the second wafer radius.

[0047] In some embodiments of the present application, the depth of the first measurement channel is 350 μm-600 μm, and the width is 2.5 mm-5 mm; the depth of the second measurement channel is 350 μm-600 μm, and the width is 2.5 mm-5 mm.

[0048] In some embodiments of the present application, the first measurement channel extends from the first side surface to the first target position along the crystal orientation of the first wafer; the second measurement channel extends from the second side surface to the second target position along the crystal orientation of the second wafer.

[0049] In some embodiments of the present application, the number of first target positions is multiple, and the corresponding number of first measurement channels is multiple; the number of second target positions is multiple, and the corresponding number of second measurement channels is multiple, the number of second target positions is equal to the number of first target positions, and the number of second measurement channels is equal to the number of first measurement channels; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide.

[0050] In some embodiments of the present application, multiple first target positions are located at different positions on the first bonding surface of the first wafer, and multiple first measurement channels extend from different positions on the first side surface of the first wafer to corresponding first target positions.

[0051] In some embodiments of the present application, multiple second target positions are located at different positions on the second bonding surface of the second wafer, and multiple second measurement channels extend from different positions on the second side surface of the second wafer to the corresponding second target positions; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded together, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide with each other.

[0052] In some embodiments of the present application, the lengths of the multiple first measurement channels are different, the lengths of the multiple second measurement channels are different, and the lengths of the first measurement channels and the corresponding second measurement channels whose projections overlap on the first bonding surface are the same.

[0053] In some embodiments of the present application, the material of the first bonding layer is the same as the material of the second bonding layer.

[0054] The embodiments of the present application may or at least have the following advantages:

[0055] In the semiconductor structure and measurement method for measuring the bonding strength of wafers in the embodiment of the present application, a first measurement channel is first formed in the first wafer, which passes through a portion of the first side surface and a portion of the first bonding surface and extends from the first side surface to a first target position on the first bonding surface. A second measurement channel is formed in the second wafer, which passes through a portion of the second side surface and a portion of the second bonding surface and extends from the second side surface to a second target position on the second bonding surface. The first wafer and the second wafer are then bonded through the first bonding layer and the second bonding layer. The projections of the first measurement channel and the second measurement channel on the first bonding surface coincide with each other, and the projections of the corresponding first target position and the second target position on the first bonding surface also coincide with each other. The first measurement channel and the second measurement channel are connected together. As the channel through which the measuring tool passes when measuring the bonding strength, the measuring tool then passes through the first measuring channel and the second measuring channel and is inserted between the first target position and the second target position, so that a crack is generated between the first target position of the first wafer and the second target position of the second wafer. By measuring the length of the crack, the bonding strength between the first target position of the first wafer and the second target position of the second wafer is obtained based on the length calculation. Since the first target position and the second target position corresponding to the formation of the first measuring channel and the second measuring channel can be any position in the middle of the first wafer and the second wafer, the above steps can realize the measurement of the bonding strength of the central area of ​​the bonding surface of the bonded wafer or even any position of the bonding surface.

[0056] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0058] Figure 1 A schematic flow chart of a method for measuring wafer bonding strength according to some embodiments of the present application;

[0059] Figure 2 A schematic structural diagram of a wafer after providing a first wafer in a wafer bonding strength measurement method provided in some embodiments of the present application;

[0060] Figure 3 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after providing a second wafer;

[0061] Figure 4 A schematic structural diagram of cleaning a first bonding surface of a first wafer or a second bonding surface of a second wafer in a method for measuring wafer bonding strength provided in some embodiments of the present application;

[0062] Figure 5 A schematic structural diagram of forming a first protective adhesive on a first bonding surface of a first wafer or forming a second protective adhesive on a second bonding surface of a second wafer in a method for measuring wafer bonding strength provided in some embodiments of the present application;

[0063] Figure 6 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after forming a first protective adhesive on a first bonding surface of a first wafer;

[0064] Figure 7 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after forming a second protective adhesive on the second bonding surface of the second wafer;

[0065] Figure 8 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after a first measurement channel is formed in a first wafer;

[0066] Figure 9A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after a second measurement channel is formed in a second wafer;

[0067] Figure 10 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after removing the first protective adhesive;

[0068] Figure 11 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after removing the second protective adhesive;

[0069] Figure 12 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after forming a first measurement channel or a second measurement channel along a crystal direction;

[0070] Figure 13 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after forming multiple first measurement channels or forming multiple second measurement channels;

[0071] Figure 14 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after a first bonding layer is formed on a first bonding surface of a first wafer;

[0072] Figure 15 A schematic structural diagram of a method for measuring wafer bonding strength provided in some embodiments of the present application after a second bonding layer is formed on a second bonding surface of a second wafer;

[0073] Figure 16 A schematic diagram of a structure after bonding a first wafer to a second wafer in a method for measuring wafer bonding strength provided in some embodiments of the present application;

[0074] Figure 17 A schematic structural diagram of annealing and sintering a first wafer and a second wafer after bonding in a method for measuring wafer bonding strength provided in some embodiments of the present application;

[0075] Figure 18 A schematic structural diagram of measuring the bonding strength of a first wafer and a second wafer after bonding in a wafer bonding strength measurement method provided in some embodiments of the present application.

[0076] Description of reference numerals:

[0077] First wafer 101; first groove 102; first protective adhesive 103; first measurement channel 104; first bonding layer 105;

[0078] Second wafer 201; second groove 202; second protective adhesive 203; second measurement channel 204; second bonding layer 205;

[0079] First target position 11; second target position 12; first circle center 13; second circle center 14; cleaning device 21; coating device 22; annealing and sintering device 23; measuring tool 24. DETAILED DESCRIPTION

[0080] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The drawings provide examples of the present application. However, the present application may be implemented in many different forms and is not limited to the examples described herein. Rather, these examples are provided to make the disclosure of the present application more thorough and comprehensive.

[0081] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0082] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to, or coupled to" another element or layer, it can be directly on, adjacent to, connected to, or coupled to the other element or layer, or there can be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to, or directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of the present application, the first element, component, region, layer, doping type, or portion discussed below may be represented as a second element, component, region, layer, or portion.

[0083] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device during use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" can include both the above and below orientations. In addition, the device can also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0084] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, within this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0085] The structures of the embodiments of the present application should not be limited to the specific shapes shown in the drawings, but include shape deviations due to, for example, manufacturing technology.

[0086] It can be understood that in the drawings of the present application, some adjacent film layers made of the same processing film material are drawn as being connected to make them close to the actual structure.

[0087] The crack propagation method, also known as the blade insertion method, is the most traditional and common method for measuring surface energy (i.e., bond strength). The process generally includes: inserting a thin blade from the side into the bonding interface of two bonded wafers, separating the two bonded wafers, and generating a crack (or gap) between the two wafers. The crack length is then measured using infrared detection or ultrasonic detection methods. Finally, the bond strength of the two wafers is calculated based on the crack length.

[0088] Due to the thinness and volatility of existing blades, the insertion depth is limited. Therefore, existing crack propagation methods can generally only measure the bond strength at the edge of the bonded wafer (2-3 cm from the side of the bonded wafer) and are unable to measure the bond strength in the center of the bonded wafer (a bonded wafer generally includes a center region and an edge region surrounding the center region). Furthermore, the deeper the blade is inserted from the side of the bonded wafer toward the bond interface, the greater the difficulty. Friction can damage the blade, causing thickness variations and inaccurate measurements. Furthermore, inserting the blade too deeply from the side of the bonded wafer toward the bond interface can easily cause the wafer to break.

[0089] To this end, an embodiment of the present application first provides a method for measuring wafer bonding strength. Figure 1 A schematic flow chart of a method for measuring wafer bonding strength provided in some embodiments of the present application.

[0090] refer to Figure 1 , a method for measuring wafer bonding strength, comprising the steps of:

[0091] Step S101, providing a first wafer, the first wafer including a first side surface, a first bonding surface and a first back surface that are opposite to each other; providing a second wafer, the second wafer including a second side surface, a second bonding surface and a second back surface that are opposite to each other;

[0092] Step S102 , forming a first measurement channel in the first wafer, wherein the first measurement channel passes through a portion of the first side surface and a portion of the first bonding surface, and extends from the first side surface to a first target position on the first bonding surface;

[0093] Step S103 , forming a second measurement channel in the second wafer, the second measurement channel passing through a portion of the second side surface and a portion of the second bonding surface, and extending from the second side surface to a second target position on the second bonding surface;

[0094] Step S104, forming a first bonding layer on the first bonding surface of the first wafer and the first measurement channel;

[0095] Step S105, forming a second bonding layer on the second bonding surface of the second wafer and the second measurement channel;

[0096] Step S106, bonding the first bonding layer and the second bonding layer, and overlapping the projections of the first measurement channel and the second measurement channel on the first bonding surface;

[0097] Step S107, providing a measuring tool, controlling the measuring tool to pass through the first measuring channel and the second measuring channel, and then inserting the measuring tool between the first target position and the second target position, so as to generate a crack between the first wafer and the second wafer;

[0098] Step S108 , measuring the length of the crack, and using a crack propagation method to calculate the bonding strength between the first target position and the second target position based on the length.

[0099] The following is combined with Figure 2 -Attached Figure 18 The specific process of the aforementioned wafer bonding strength measurement method is described in detail.

[0100] First, combined with reference Figure 1 and Figure 2 , proceed to step S101, providing a first wafer 101 (reference Figure 1 ), the first wafer 101 includes a first side surface and a first bonding surface and a first back surface that are separated from each other; providing a second wafer 201 (reference Figure 2 ), the second wafer 201 includes a second side surface and a second bonding surface and a second back surface that are opposite to each other.

[0101] The first wafer 101 and the second wafer 201 are two wafers that need to be bonded together for bond strength measurement. In some embodiments, since the subsequent bond strength measurement is destructive, in order to save costs, the first wafer 101 and the second wafer 201 are bare wafers, and a first bonding layer is subsequently generated on the first bonding surface of the first wafer 101, and a second bonding layer is grown on the second bonding surface of the second wafer 201 to simulate the bonding of a real chip. It should be noted that in other embodiments, without considering the cost, semiconductor devices or integrated circuits corresponding to the structure in the real chip can also be formed in the first wafer 101 and the second wafer 201, and the surfaces of the first wafer 101 and the second wafer to be bonded are used as the first bonding surface and the second bonding surface, respectively.

[0102] The first wafer 101 has a first bonding surface and a first back surface facing away from each other, and the first side surface is located between the first bonding surface and the first back surface. Figure 2 As shown, the upper surface of the first wafer 101 can be used as the first bonding surface, the lower surface of the first wafer 101 can be used as the first back surface, and the annular side surface of the first wafer 101 can be used as the first side surface. In some embodiments, the first side surface of the first wafer 101 further has a first notch 102. The first notch 102 can be used to mark the crystal orientation of the first wafer 101, such as <100> , <110> , <111> On the other hand, it can be used as a positioning mark and alignment mark in the subsequent process.

[0103] The second wafer 201 has a second bonding surface and a second back surface facing away from each other, and the second side surface is located between the second bonding surface and the second back surface. Figure 3As shown, the upper surface of the second wafer 201 can be used as the second bonding surface, the lower surface of the second wafer 201 can be used as the second back surface, and the annular side surface of the second wafer 201 can be used as the second side surface. In some embodiments, the second side surface of the second wafer 201 further has a second notch 202. The second notch 202 can be used to mark the crystal orientation of the second wafer 201, such as <100> , <110> , <111> On the other hand, it can be used as a positioning mark and alignment mark in the subsequent process.

[0104] In some embodiments, the size of the first wafer 101 is the same as the size of the second wafer 201, for example, both can be 8-inch wafers or 12-inch wafers, or wafers of other sizes. The thickness of the first wafer 101 is the same as the thickness of the second wafer 201, for example, both can be 750 microns ± 50 microns, or other thicknesses. The material of the first wafer 101 is the same as the material of the second wafer 201, for example, both can be silicon materials, or both can be other semiconductor materials such as silicon carbide or silicon germanium materials.

[0105] In other embodiments, in order to meet the measurement of bonding strength under different circumstances, one or more of the size of the first wafer 101 and the size of the second wafer 201, the thickness of the first wafer 101 and the thickness of the second wafer 201, and the material of the first wafer 101 and the material of the second wafer 201 may be different. For example, when the size of the first wafer 101 is the same as the size of the second wafer 201 and the material of the first wafer 101 is the same as the material of the second wafer 201, the thickness of the first wafer 101 and the thickness of the second wafer 201 may be different. For another example, when the size of the first wafer 101 is the same as the size of the second wafer 201 and the thickness of the first wafer 101 is the same as the thickness of the second wafer 201, the material of the first wafer 101 and the material of the second wafer 201 may be different.

[0106] In some embodiments, both the first wafer 101 and the second wafer 201 include a central region and an edge region surrounding the central region. The edge region is the region of the first wafer 101 near the first side, or the region of the second wafer 201 near the second side. In one example, the edge region can be the region of the first wafer less than 3 microns from the first side, or the region of the second wafer less than 3 microns from the second side. After the first wafer 101 and the second wafer 201 are subsequently bonded, the bonding surfaces of the two wafers can include the central region and the edge region surrounding the central region.

[0107] In some embodiments, before forming the first measurement channel in the first wafer 101 and before forming the second measurement channel in the second wafer 201, Figure 3, also includes: cleaning the first wafer 101 and the second wafer 201 to remove contaminants on the surface of the first wafer 101 and the second wafer 201, which is beneficial to improving the strength of the subsequent bonding of the first wafer 101 and the second wafer 201. In one example, a cleaning device or a cleaning device 21 can be used to clean the first wafer 101 and the second wafer 201.

[0108] In some embodiments, before forming the first measurement channel in the first wafer 101, referring to Figure 6 , further comprising: forming a first protective glue 103 on the first bonding surface of the first wafer 101, the first protective glue 103 preventing the generated debris from contaminating or damaging the first bonding surface of the first wafer 101 when the first measurement channel is subsequently formed in the first wafer 101, the first protective glue 103 can be made of a photoresist or other glue that is easy to form and easy to clean and remove. In one example, reference Figure 5 , a coating device or coating equipment is used to form the first protective glue 103 through a spin coating process.

[0109] In some embodiments, before forming the second measurement channel in the second wafer 201, referring to Figure 7 , further comprising: forming a second protective glue 203 on the second bonding surface of the second wafer 201, the second protective glue 203 preventing the generated debris from contaminating or damaging the second bonding surface of the second wafer 201 when the second measurement channel is subsequently formed in the second wafer 201, the second protective glue 203 can be made of a photoresist or other glue that is easy to form and easy to clean and remove. In one example, reference Figure 5 , a coating device or coating equipment is used to form the second protective glue 203 through a spin coating process.

[0110] Next, combined with reference Figure 1 and Figure 8 , proceed to step S102, forming a first measurement channel 104 in the first wafer 101, the first measurement channel 104 passing through a portion of the first side surface and a portion of the first bonding surface, and extending from the first side surface to the first target position 11 on the first bonding surface; Figure 10 After forming the first measuring channel 104, remove the first protective glue 103 (refer to Figure 8 ).

[0111] In the present application, a first measurement channel 104 is formed in advance in the first wafer 101, which penetrates a portion of the first side surface and a portion of the first bonding surface and extends from the first side surface to a first target position on the first bonding surface. Subsequently, a second measurement channel 204 is formed in the second wafer 201, which penetrates a portion of the second side surface and a portion of the second bonding surface and extends from the second side surface to a second target position on the second bonding surface (refer to Figure 11), after the first wafer 101 and the second wafer 201 are bonded via the first bonding layer 105 and the second bonding layer 205 (refer to Figure 16 ), the projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface coincide with each other, and the projections of the corresponding first target position 11 and the second target position 12 on the first bonding surface also coincide with each other, and the first measurement channel 104 and the second measurement channel 204 are used together as the measurement tool 24 for bond strength measurement (reference Figure 18 ) passes through the channel, and after the measuring tool 24 passes through the first measuring channel 104 and the second measuring channel 204, it is inserted between the first target position 11 and the second target position 12, so that a crack is generated between the first target position 11 of the first wafer 101 and the second target position 12 of the second wafer 201. By measuring the length of the crack, the bonding strength between the first target position 11 of the first wafer 101 and the second target position 12 of the second wafer 201 is obtained based on the length calculation. Since the first target position 11 and the second target position 12 corresponding to the formation of the first measuring channel 104 and the second measuring channel 204 can be the central area of ​​the bonding surface of the first wafer 101 and the second wafer 201, or even any position of the entire bonding surface, the above steps can be used to measure the bonding strength of the central area of ​​the bonding surface of the bonded wafers, or even any position of the entire bonding surface.

[0112] In some embodiments, a grinding wheel cutting process is used to form the first measurement channel 104 in the first wafer 101. Because the formed first measurement channel 104 is generally deep, the grinding wheel cutting process can quickly and accurately form the first measurement channel 104. In some embodiments, after the grinding wheel cutting process, cleaning is performed to remove cutting residue and the first protective adhesive 103. Cleaning can be performed using a wet cleaning process or a dry cleaning process.

[0113] In some embodiments, the sidewall of the first measurement channel 104 facing away from the first side surface is an inclined sidewall, and the inclined direction of the inclined sidewall is inclined in a direction away from the first side surface of the first wafer 101. Formation of the inclined sidewall: When a grinding wheel cutting process is used, when the grinding wheel cuts the first wafer 101, the sidewall of the first measurement channel 104 facing away from the first side surface will be inclined. When the sidewall of the first measurement channel 104 facing away from the first side surface is an inclined sidewall, the subsequent Figure 11 ) formed in the second measurement channel 204 (reference Figure 11) is also an inclined sidewall. Subsequently, after the first wafer 101 and the second wafer 201 are bonded correspondingly, the first measurement channel 104 and the second measurement channel 204 jointly serve as a channel for the measuring tool to pass through. The inclined sidewall of the first measurement channel 104 facing away from the first side surface and the inclined sidewall of the second measurement channel 204 facing away from the second side surface can adapt to the shape of the tip of the measuring tool when they cooperate with each other (the measuring tool generally includes a tip and a blade body connected to the tip. The tip may include a first blade surface and a second blade surface facing each other. Both the first blade surface and the second blade surface are inclined blade surfaces, that is, the vertical distance between the first blade surface and the second blade surface gradually decreases from the front end of the tip away from the blade body to the blade body), so as to limit the moving direction of the tip of the measuring tool, so that the tip can be accurately inserted into the bonding interface between the first target position 11 of the first wafer 101 and the second target position 12 of the second wafer 201, which is conducive to improving the accuracy of measurement. It should be noted that, in other embodiments, according to measurement requirements, the sidewall of the first measurement channel 104 facing away from the first side surface may also be of other shapes.

[0114] In some embodiments, the number of the first measurement channel 104 and the second measurement channel 204 formed in the subsequent second wafer 201 are both one, and the length and width of the first measurement channel 104 are correspondingly the same as the length and width of the second measurement channel 204. After the subsequent first wafer 101 and the second wafer 201 are bonded, the channel formed by the first measurement channel 104 and the second measurement channel 204 is a channel with a regular shape, which is convenient for the measurement tool to pass through and facilitates the design of the measurement tool size and shape.

[0115] The depth of the first measurement channel 104 is preferably such that it does not affect subsequent wafer bonding. Figure 10The depth D1 of the formed first measurement channel 104 is 40%-85% of the thickness D2 of the first wafer 101. Specifically, the depth D1 of the first measurement channel 104 is 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, and 85% of the thickness D2 of the first wafer 101. At the aforementioned specific depths, on the one hand, it will not affect the subsequent bonding of the first wafer and the second wafer. On the other hand, when the bonding strength is subsequently measured, the height or thickness of the measuring tool used needs to be adapted to the total depth of the first measurement channel and the second measurement channel. When the first measurement channel 104 is within this depth range, the design of the measuring tool is correspondingly performed so that the measuring tool can maintain a larger height or thickness, which can improve the rigidity of the measuring tool and prevent the tool from being deformed during the bonding strength measurement, thereby affecting the measurement accuracy. The first target position 11 on the first bonding surface of the first wafer 101 and the second target position 12 on the second bonding surface of the second wafer 201 are overlapped after the first wafer 101 and the second wafer 201 are subsequently bonded. The first target position 11 and the center of the first wafer 101 (the first center 13, reference Figure 13 ) is ≤ 3 / 4 times the radius r1 of the first wafer 101. That is, the first target position can be any position on the first bonding surface of the first wafer 101 near the center of the circle. Therefore, after the first wafer 101 and the second wafer 201 are subsequently bonded, the bond strength of the central area of ​​the bonding surface of the bonded wafers, or even any position on the bonding surface, can be measured. In a specific example, when the thickness D2 of the first wafer 101 is 750 μm ± 50 μm, the depth D1 of the first measurement channel 104 is 350 μm to 600 μm, specifically 350 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, or 600 μm, and the width W1 is 2.5 mm to 5 mm, specifically 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm. The length L1 of the first measurement channel 104 varies depending on the first target position 11.

[0116] Next, combined with reference Figure 1 and Figure 9 , proceed to step S103, forming a second measurement channel 204 in the second wafer 201, the second measurement channel 204 passing through a portion of the second side surface and a portion of the second bonding surface, and extending from the second side surface to the second target position 12 on the second bonding surface; Figure 11 After forming the second measuring channel 204, remove the second protective glue 203 (refer to Figure 9 ).

[0117] The second measurement channel 204 serves as a portion of the channel through which a measuring tool passes when measuring the bonding strength after the first wafer 101 and the second wafer 201 are subsequently bonded.

[0118] In some embodiments, a grinding wheel cutting process is used to form the second measurement channel 204 in the second wafer 201. Because the formed second measurement channel 204 is generally deep, the grinding wheel cutting process can quickly and accurately form the second measurement channel 204. In some embodiments, after the grinding wheel cutting process, cleaning is performed to remove cutting residue and the second protective adhesive 203. Cleaning can be performed using a wet cleaning process or a dry cleaning process.

[0119] In some embodiments, the sidewall of the second measurement channel 204 facing away from the second side surface is an inclined sidewall, and the inclined sidewall is inclined in a direction away from the second side surface of the second wafer 201 that is penetrated. Formation of the inclined sidewall: When a grinding wheel is used for cutting, the grinding wheel cuts the second wafer 201, causing the sidewall of the second measurement channel 204 facing away from the second side surface to be inclined. It should be noted that in other embodiments, the sidewall of the second measurement channel 204 facing away from the second side surface may also have other shapes depending on measurement requirements.

[0120] In some embodiments, the number of the first measurement channel 104 and the second measurement channel 204 subsequently formed in the second wafer 201 is one, and the length and width of the second measurement channel 204 are correspondingly the same as those of the first measurement channel 104 .

[0121] The depth of the second measurement channel 204 is preferably such that it does not affect subsequent wafer bonding. In some embodiments, the depth of the second measurement channel 204 is 40%-85% of the thickness of the second wafer 201. Specifically, the depth of the second measurement channel 204 is 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85% of the thickness of the second wafer 201. At these specific depths, on the one hand, the subsequent bonding of the second wafer to the first wafer is not affected. On the other hand, when subsequently measuring the bond strength, the height or thickness of the measuring tool used needs to be compatible with the total depth of the second measurement channel and the first measurement channel. When the second measurement channel 204 is within this depth range, the corresponding design of the measuring tool allows the measuring tool to maintain a larger height or thickness, thereby improving the rigidity of the measuring tool and preventing deformation of the tool during bond strength measurement, which could affect the measurement accuracy. The second target position 12 on the second bonding surface of the second wafer 201 and the first target position 11 on the first bonding surface of the first wafer 101 are also overlapped in projection on the first bonding surface after the second wafer 201 and the first wafer 101 are subsequently bonded. The second target position 12 and the center of the second wafer 201 (the second center 14, reference Figure 13) is ≤ 3 / 4 times the radius r2 of the second wafer 201. That is, the second target position can be any position on the second bonding surface of the second wafer 201 near the center of the circle. Therefore, after the second wafer 201 and the first wafer 101 are subsequently bonded, the bond strength of any position in the central area of ​​the bonded wafers can be measured. In a specific example, when the thickness of the second wafer 201 is 750 μm ± 50 μm, the depth of the second measurement channel 204 is 350 μm to 600 μm, specifically 350 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, or 600 μm, and the width is 2.5 mm to 5 mm, specifically 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm. The length L1 of the second measurement channel 204 varies depending on the second target position 12.

[0122] It should be noted that, when performing step S102 and step S103, step S102 may be performed first and then step S103, or step S103 may be performed first and then step S102.

[0123] In some embodiments, reference Figure 12 When forming the first measurement channel 104 and the second measurement channel 204, the first measurement channel 104 can be cut along the crystal direction of the first wafer 101 (for example, the crystal direction <100> Or crystal orientation <110> ) is cut, that is, the formed first measurement channel 104 extends from the first side surface to the first target position 11 along the crystal direction of the first wafer 101, and the second measurement channel 204 can be cut along the crystal direction of the second wafer 201 (for example <100> Crystal orientation or <110> The second measurement channel 204 is formed by cutting along the crystal direction of the second wafer 201, that is, extending from the second side surface to the second target position 12. Since the Young's modulus of different crystal directions on the wafer is different, for example <110> The Young's modulus of the crystal direction is 1.70 *10 11 pa, <100> The Young's modulus of the crystal direction is 1.30 *10 11 When both the first measurement channel 104 and the second measurement channel 204 extend along the crystal direction, the Young's modulus of the first wafer 101 and the second wafer 201 corresponding to the measurement positions (the first target position and the second target position) can be accurately obtained during the subsequent bond strength measurement, thereby improving the accuracy of the bond strength measurement. Figure 12 The wafer shown in FIG. 1 may represent both the second wafer 201 and the first wafer 101 .

[0124] In some embodiments, reference Figure 13The number of first target positions 11 can be multiple, such as 2-6, and the corresponding number of first measurement channels 104 can be multiple, such as 2-6, and the number of first measurement channels 104 is equal to the number of first target positions; the number of second target positions 12 can be multiple, such as 2-6, and the corresponding number of second measurement channels 204 can be multiple, such as 2-6, and the number of second measurement channels 204 is equal to the number of second target positions 12, and the number of second target positions 12 is equal to the number of first target positions 11, and the number of second measurement channels 204 is equal to the number of first measurement channels 104; when the first bonding layer 105 of the first wafer 101 and the second bonding layer 205 of the second wafer 201 are bonded, the projections of the multiple first measurement channels 104 and the corresponding second measurement channels 204 on the first bonding surface coincide. That is, in the bonded wafer, different first measurement channels 104 and corresponding second measurement channels 204 can provide channels for performing bond strength measurements at different positions, thereby measuring the bond strength at different positions in the center area of ​​the bonded wafer. It should be noted that, in order to explain more clearly, Figure 13 The wafer shown in FIG. 1 may represent both the second wafer 201 and the first wafer 101 .

[0125] In one embodiment, continue to refer to Figure 3 Multiple first target locations 11 are located at different locations on the first bonding surface of first wafer 101, and multiple first measurement channels 104 extend from different locations on the first side of first wafer 101 to corresponding first target locations 11. Correspondingly, multiple second target locations 12 are located at different locations on the second bonding surface of second wafer 201, and multiple second measurement channels 204 extend from different locations on the second side of second wafer 201 to corresponding second target locations 12. Furthermore, the multiple first measurement channels 104 have different lengths, and the corresponding multiple second measurement channels 204 have different lengths. First measurement channels 104 and corresponding second measurement channels 204 that overlap on the first bonding surface have the same length. Subsequently, after first wafer 101 and second wafer 201 are bonded, the measurement channels formed by the different first measurement channels 104 and corresponding second measurement channels 204 can have different distances from the center of the circle (first center 13 or second center 14), thereby enabling measurement of the bond strength at different distances from the center of the circle (first center 13 or second center 14) on the bonded wafers.

[0126] Next, combined with reference Figure 1 and Figure 14 , proceed to step S104, forming a first bonding layer 105 on the first bonding surface of the first wafer 101 and the first measurement channel 104; Figure 1 and Figure 15, proceed to step S105 , forming a second bonding layer 205 on the second bonding surface of the second wafer 201 and the second measurement channel 204 .

[0127] The first bonding layer 105 and the second bonding layer 205 are made of the same material. Their thickness is much smaller than that of the first wafer 101 or the second wafer 201. The thickness of the first wafer 101 or the second wafer 201 is on the order of several hundred microns (e.g., 600-800 microns), while the thickness of the first bonding layer 105 and the second bonding layer 205 is on the nanometer scale. In some embodiments, the thickness of the first bonding layer 105 and the second bonding layer 205 is 5-50 nm. In some embodiments, the first bonding layer 105 and the second bonding layer 205 are made of silicon oxide or silicon carbide nitride.

[0128] In a specific embodiment, the material of the first bonding layer 105 and the second bonding layer 205 is silicon oxide, and the first bonding layer 105 and the second bonding layer 205 are formed by a thermal oxidation process. In this case, the formed first bonding layer 105 and the second bonding layer 205 will cover the first bonding surface and the second bonding surface respectively, while the first bonding layer material (silicon oxide material) will not be formed on the opening of the first measuring channel 104 located on the first bonding surface, and the second bonding layer material (silicon oxide material) will not be formed on the opening of the second measuring channel 204 located on the second bonding surface. However, a thinner silicon oxide material (not shown in the figure) will be formed on the inner walls of the first measuring channel 104 and the second measuring channel 204. The silicon oxide on the inner wall surface of the first measuring channel 104 and the second measuring channel 204 is very thin and will not affect the subsequent measurement tool passing through the measurement channel formed by the first measuring channel 104 and the second measuring channel 204.

[0129] In another specific embodiment, the material of the first bonding layer 105 and the second bonding layer 205 is silicon carbide nitride, and the first bonding layer 105 and the second bonding layer 205 are formed by a chemical vapor deposition process. In this case, the formed first bonding layer 105 and the second bonding layer 205 will correspondingly cover the first bonding surface and the second bonding surface. Since the depth of the first measurement channel 104 and the second measurement channel 204 is much larger than the thickness of the formed first bonding layer 105 and the second bonding layer 205, during the chemical vapor deposition process, the opening of the first measurement channel 104 located at the first bonding surface may be closed by the first bonding layer material (silicon carbide nitride material), and the opening of the second measurement channel 204 located at the second bonding surface may be closed by the second bonding layer material (silicon carbide nitride material). However, the silicon nitride materials are very thin, and therefore will not affect the subsequent measurement tool passing through the measurement channel formed by the first measurement channel 104 and the second measurement channel 204.

[0130] In some embodiments, after forming the first bonding layer 105 and the second bonding layer 205 , a chemical mechanical polishing process can be performed on the first bonding layer 105 and the second bonding layer 205 to further improve the flatness of the first bonding layer 105 and the second bonding layer 205 , so as to improve the bonding strength when the first wafer 101 and the second wafer 201 are subsequently bonded.

[0131] In one embodiment, after the first bonding layer 105 and the second bonding layer 205 are formed, the surfaces of the first bonding layer 105 and the second bonding layer 205 can be plasma activated to activate the surfaces of the first bonding layer 105 and the second bonding layer 205, and deionized water cleaning can be performed to further remove impurities on the surfaces of the first bonding layer 105 and the second bonding layer 205, thereby further improving the bonding strength when the first wafer 101 and the second wafer 201 are subsequently bonded.

[0132] refer to Figure 1 Combined with reference Figure 16 , proceed to step S106 , bonding the first bonding layer 105 and the second bonding layer 205 , so that the projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface overlap.

[0133] After the first wafer 101 and the second wafer 201 are aligned, the first bonding layer 105 of the first wafer 101 is attached to the second bonding layer 205 of the second wafer 201 , so that the first bonding layer 105 and the second bonding layer 205 are bonded together.

[0134] In some embodiments, after aligning and bonding the first wafer 101 and the second wafer 201, a super junction annealing process is further performed on the first wafer 101 and the second wafer 201 to form a permanent covalent bond between the first bonding layer 105 and the second bonding layer 205. In one example, the super junction annealing process is performed in a super junction annealing device or equipment, and the temperature range of the super junction annealing process is 280 degrees Celsius to 320 degrees Celsius, and the time range of the super junction annealing process is 1.5 hours to 2.5 hours.

[0135] Next, combined with reference Figure 1 , Figure 16 and Figure 18 , proceed to step S107, provide the measuring tool 24, control the measuring tool 24 to pass through the first measuring channel 104 and the second measuring channel 204 (reference Figure 16 ) is inserted between the first target position 11 and the second target position 12, so that a crack 15 is generated between the first wafer 101 at the first target position 11 and the second wafer 201 at the second target position 12 (reference Figure 18 ).

[0136] The size and shape of the measuring tool 24 match the size and shape of the measuring channel formed by the first measuring channel 104 and the second measuring channel 204. In some embodiments, the width of the measuring tool 24 is less than or equal to the width of the first measuring channel 104 and the width of the second measuring channel 204, the height of the measuring tool 24 is less than or equal to the sum of the depths of the first measuring channel 104 and the depths of the second measuring channel 204, and the length of the measuring tool 24 is greater than the lengths of the first measuring channel 104 and the second measuring channel 204. In one example, when the widths of the first measuring channel 104 and the second measuring channel 204 are 3 mm and the sum of the depths of the first measuring channel 104 and the second measuring channel 204 is 0.8 mm, the width of the measuring tool 24 may be 2 mm, the height may be 0.7 mm, and the length may be greater than the lengths of the first measuring channel 104 and the second measuring channel 204.

[0137] In some embodiments, the measuring tool 24 may include a blade tip connected to a blade body, wherein the width of the blade tip is equal to the width of the blade body, and the height of the blade tip is less than the height of the blade body. When the measuring tool is inserted between the first target position 11 and the second target position 12, the blade tip is first inserted between the first target position 11 and the second target position 12, and then the blade body is inserted between the first target position 11 and the second target position 12. In some embodiments, the blade tip may include a first blade surface and a second blade surface that are opposed to each other, and the first blade surface and the second blade surface are both inclined blade surfaces, i.e., the vertical distance between the first blade surface and the second blade surface gradually decreases from the front end of the blade tip away from the blade body toward the blade body.

[0138] In some embodiments, the measuring tool 24 may be inserted manually or automatically by related equipment.

[0139] Finally, continue to refer to Figure 1 and Figure 18 , proceed to step S108 , measure the length L of the crack 15 , and calculate the bonding strength between the first target position 11 (of the first wafer 101 ) and the second target position 12 (of the second wafer 201 ) based on the length L using a crack propagation method.

[0140] In some embodiments, the length of the crack can be measured using an infrared measurement method or an ultrasonic measurement method, specifically an infrared measuring instrument or an ultrasonic measuring instrument. Figure 18 The crack 15 shown in FIG. 1 is a corresponding light and dark stripe obtained when measuring a real crack between the first wafer 101 and the second wafer 201 using an infrared measuring instrument.

[0141] In one embodiment, obtaining the bonding strength at the first target position 11 and the second target position 12 based on length calculation using the crack propagation method includes: calculating the bonding strength using the following formula:

[0142] Y=(3t b E1E2t w1 3 t w2 3 ) / 16L 4 (E1t w1 3 +E2t w2 3 ),

[0143] Y represents the bond strength, t b represents the height of the measuring tool 24, E1 represents the Young's modulus of the first wafer 101, E2 represents the Young's modulus of the second wafer 201, t w1 represents the thickness of the first wafer 101, t w2 represents the thickness of the second wafer 201 , and L represents the length of the crack 15 .

[0144] In some embodiments, when the first wafer 101 and the second wafer 201 have the same thickness, the same material, and the same size, the corresponding calculated bonding strength may be changed to:

[0145] Y=3Et 3 t b 2 / 32L 4 , where Y represents the bonding strength, E represents the Young's modulus of the first wafer 101 or the second wafer 201, t represents the thickness of the first wafer 101 or the second wafer 201, and t b represents the height of the measuring tool 24 and L represents the length of the crack 15 .

[0146] The present application also provides a semiconductor structure for measuring wafer bonding strength, referring to Figure 16 ,include:

[0147] A first wafer 101, the first wafer 101 includes a first side surface and a first bonding surface and a first back surface that are separated from each other;

[0148] A first measurement channel 104 is located in the first wafer 101 , and the first measurement channel 104 passes through a portion of the first side surface and a portion of the first bonding surface, and extends from the first side surface to the first target position 11 on the first bonding surface;

[0149] A first bonding layer 105 is located on the first bonding surface of the first wafer 101 and the first measurement channel 104;

[0150] A second wafer 201, the second wafer 201 comprising a second side surface and a second bonding surface and a second back surface that are separated from each other;

[0151] A second measurement channel 204 is located in the second wafer 201 . The second measurement channel 204 passes through a portion of the second side surface and a portion of the second bonding surface, and extends from the second side surface to the second target position 12 on the second bonding surface.

[0152] A second bonding layer 205 is located on the second bonding surface of the second wafer 201 and the second measurement channel 204;

[0153] The first bonding layer 105 of the first wafer 101 and the second bonding layer 205 of the second wafer 201 are bonded, and the projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface overlap. The first measurement channel 104 and the second measurement channel 204 constitute a measurement channel for measuring the bonding strength as a measuring tool 24 (refer to FIG. Figure 18 ) passes through the channel, so that the measuring tool 24 passes through the first measuring channel 104 and the second measuring channel 204 and is inserted between the first target position 11 and the second target position 12, and a crack 15 is generated between the first wafer 101 at the first target position 11 and the second wafer 201 at the second target position 12.

[0154] In some embodiments, the sidewall of the first measurement channel 104 facing away from the first side surface is an inclined sidewall; and the sidewall of the second measurement channel 204 facing away from the second side surface is an inclined sidewall.

[0155] In some embodiments, the number of the first measurement channel 104 and the number of the second measurement channel 204 are both one, and the length and width of the first measurement channel 104 are correspondingly the same as the length and width of the second measurement channel 204 .

[0156] In some embodiments, the depth of the first measurement channel 104 is 40%-85% of the thickness of the first wafer 101; the depth of the second measurement channel 204 is 40%-85% of the thickness of the second wafer 201. For example, for a 100 mm (4 inch) diameter wafer, the thickness is typically about 525 µm; for a 150 mm (6 inch) diameter wafer, the thickness is typically about 675 µm; for a 200 mm (8 inch) diameter wafer, the thickness is typically about 725 µm; and for a 300 mm (12 inch) diameter wafer, the thickness is typically about 775 µm. The depths of the first and second measurement channels must be such that they do not affect the bonding between the first and second wafers.

[0157] In some embodiments, the straight-line distance between the first target position 11 and the center of the first wafer 101 is ≤ 3 / 4 times the radius of the first wafer 101 ; the straight-line distance between the second target position 12 and the center of the second wafer 201 is ≤ 3 / 4 times the radius of the second wafer 201 .

[0158] In some embodiments, the first measurement channel 104 has a depth of 350 μm to 600 μm and a width of 2.5 mm to 5 mm; the second measurement channel 204 has a depth of 350 μm to 600 μm and a width of 2.5 mm to 5 mm.

[0159] In some embodiments, the first measurement channel 104 extends from the first side surface to the first target position 11 along the crystal orientation of the first wafer 101 ; the second measurement channel 204 extends from the second side surface to the second target position 12 along the crystal orientation of the second wafer 201 .

[0160] In some embodiments, there are multiple first target positions 11, and the corresponding number of first measurement channels 104 is multiple; there are multiple second target positions 12, and the corresponding number of second measurement channels 204 is multiple, the number of second target positions 12 is equal to the number of first target positions 11, and the number of second measurement channels 204 is equal to the number of first measurement channels 104; when the first bonding layer 105 of the first wafer 101 and the second bonding layer 205 of the second wafer 201 are bonded together, the projections of the multiple first measurement channels 104 and the corresponding second measurement channels 204 on the first bonding surface coincide.

[0161] In some embodiments, the plurality of first target positions 11 are located at different positions of the first bonding surface of the first wafer 101 , and the plurality of first measurement channels 104 extend from different positions of the first side surface of the first wafer 101 to the corresponding first target positions 11 .

[0162] In some embodiments, multiple second target locations 12 are located at different locations on the second bonding surface of the second wafer 201, and multiple second measurement channels 204 extend from different locations on the second side surface of the second wafer 201 to corresponding second target locations 12. The multiple first measurement channels 104 have different lengths, the multiple second measurement channels 204 have different lengths, and first measurement channels 104 and corresponding second measurement channels 204 whose projections overlap on the first bonding surface have the same length.

[0163] In some embodiments, the material of the first bonding layer 105 is the same as the material of the second bonding layer 205 .

[0164] In some embodiments, the material of the first bonding layer 105 and the second bonding layer 205 is silicon oxide or silicon carbide nitride.

[0165] It should be noted that the limitations or descriptions of the same or similar parts in this embodiment (semiconductor structure for measuring wafer bonding strength) and the aforementioned embodiment (method for measuring wafer bonding strength) will not be repeated in this embodiment. Please refer to the limitations or descriptions of the corresponding parts in the aforementioned embodiment for details.

[0166] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" mean that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present application. Within this specification, the illustrative descriptions of these terms do not necessarily refer to the same embodiment or example.

[0167] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0168] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for measuring wafer bonding strength, characterized in that: include: Providing a first wafer, wherein the first wafer includes a first side surface and a first bonding surface and a first back surface that are separated from each other; Providing a second wafer, the second wafer comprising a second side surface and a second bonding surface and a second back surface that are separated from each other; forming a first measurement channel in the first wafer, wherein the first measurement channel passes through a portion of the first side surface and a portion of the first bonding surface, and extends from the first side surface to a first target position on the first bonding surface; forming a second measurement channel in the second wafer, wherein the second measurement channel passes through a portion of the second side surface and a portion of the second bonding surface, and extends from the second side surface to a second target position on the second bonding surface; forming a first bonding layer on the first bonding surface of the first wafer and the first measurement channel; forming a second bonding layer on the second bonding surface and the second measurement channel of the second wafer; Bonding the first bonding layer and the second bonding layer, so that the projections of the first measurement channel and the second measurement channel on the first bonding surface overlap; Providing a measuring tool, controlling the measuring tool to pass through the first measuring channel and the second measuring channel and then be inserted between the first target position and the second target position, so as to generate a crack between the first wafer and the second wafer; The length of the crack is measured, and the bonding strength between the first target position and the second target position is calculated based on the length using a crack propagation method.

2. The method for measuring wafer bonding strength according to claim 1, wherein: The method of using the crack propagation method to calculate the bonding strength at the first target position and the second target position based on the length includes: calculating the bonding strength using the following formula: Y=(3t b 2 E1E2t w1 3 t w2 3 ) / 16L 4 (E1t w1 3 +E2t w2 3 ), Where Y represents the bond strength, t b represents the height of the measuring tool, E1 represents the Young's modulus of the first wafer, E2 represents the Young's modulus of the second wafer, t w1 represents the thickness of the first wafer, t w2 represents the thickness of the second wafer, and L represents the length of the crack.

3. The method for measuring wafer bonding strength according to claim 1 or 2, wherein: The length of the crack is measured using an infrared measuring instrument or an ultrasonic measuring instrument.

4. The method for measuring wafer bonding strength according to claim 1, wherein: The first measurement channel is formed in the first wafer and the second measurement channel is formed in the second wafer by using a grinding wheel cutting process.

5. The method for measuring wafer bonding strength according to claim 4, wherein: The side wall of the first measuring channel facing away from the first side surface is an inclined side wall; the side wall of the second measuring channel facing away from the second side surface is an inclined side wall.

6. The method for measuring wafer bonding strength according to claim 4, wherein: Before forming the first measurement channel in the first wafer, forming a first protective glue on the first bonding surface, and after forming the first measurement channel, removing the first protective glue; Before forming the second measurement channel in the second wafer, a second protective adhesive is formed on the second bonding surface, and after forming the second measurement channel, the second protective adhesive is removed.

7. The method for measuring wafer bonding strength according to claim 1, wherein: The number of the first measurement channel and the number of the second measurement channel are both one, and the length and width of the first measurement channel are correspondingly the same as the length and width of the second measurement channel.

8. The method for measuring wafer bonding strength according to claim 7, wherein: The depth of the first measurement channel is 40%-85% of the thickness of the first wafer; the depth of the second measurement channel is 40%-85% of the thickness of the second wafer.

9. The method for measuring wafer bonding strength according to claim 7, wherein: The straight-line distance between the first target position and the center of the first wafer is ≤3 / 4 times the radius of the first wafer; the straight-line distance between the second target position and the center of the second wafer is ≤3 / 4 times the radius of the second wafer.

10. The method for measuring wafer bonding strength according to claim 7, wherein: The first measurement channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters; the second measurement channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters.

11. The method for measuring wafer bonding strength according to claim 7, wherein: The first measurement channel extends from the first side surface to the first target position along the crystal direction of the first wafer; the second measurement channel extends from the second side surface to the second target position along the crystal direction of the second wafer.

12. The method for measuring wafer bonding strength according to claim 1, wherein: There are multiple first target positions, and the corresponding number of first measurement channels is multiple; there are multiple second target positions, and the corresponding number of second measurement channels is multiple, the number of second target positions is equal to the number of first target positions, and the number of second measurement channels is equal to the number of first measurement channels; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide.

13. The method for measuring wafer bonding strength according to claim 12, wherein: The plurality of first target positions are located at different positions of the first bonding surface of the first wafer, and the plurality of first measurement channels extend from different positions of the first side surface of the first wafer to corresponding first target positions.

14. The method for measuring wafer bonding strength according to claim 13, wherein: The plurality of second target positions are located at different positions on the second bonding surface of the second wafer, and the plurality of second measurement channels extend from different positions on the second side surface of the second wafer to corresponding second target positions.

15. The method for measuring wafer bonding strength according to claim 14, wherein: The lengths of the plurality of first measurement channels are different, the lengths of the plurality of second measurement channels are different, and the lengths of the first measurement channels and the corresponding second measurement channels whose projections overlap on the first bonding surface are the same.

16. The method for measuring wafer bonding strength according to claim 1, 7 or 12, wherein: The width of the measuring tool is less than or equal to the width of the first measuring channel and the width of the second measuring channel, the height of the measuring tool is less than or equal to the sum of the depth of the first measuring channel and the depth of the second measuring channel, and the length of the measuring tool is greater than the length of the first measuring channel and the length of the second measuring channel.

17. The method for measuring wafer bonding strength according to claim 16, wherein: The measuring tool comprises a blade tip and a blade body connected to the blade tip, the width of the blade tip is equal to the width of the blade body, and the height of the blade tip is less than the height of the blade body; When the measuring tool is inserted between the first target position and the second target position, the tool tip is first inserted between the first target position and the second target position, and then the tool body is inserted between the first target position and the second target position.

18. A semiconductor structure for measuring wafer bonding strength, characterized in that: include: A first wafer, comprising a first side surface and a first bonding surface and a first back surface that are separated from each other; a first measurement channel located in the first wafer, the first measurement channel penetrating a portion of the first side surface and a portion of the first bonding surface, and extending from the first side surface to a first target position on the first bonding surface; a first bonding layer, located on the first bonding surface of the first wafer and the first measurement channel; a second wafer comprising a second side surface and a second bonding surface and a second back surface that are separated from each other; a second measurement channel located in the second wafer, the second measurement channel penetrating a portion of the second side surface and a portion of the second bonding surface, and extending from the second side surface to a second target position on the second bonding surface; a second bonding layer, located on the second bonding surface and the second measurement channel of the second wafer; The first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, and the projections of the first measurement channel and the second measurement channel on the first bonding surface overlap. The first measurement channel and the second measurement channel are used as channels for a measuring tool to pass through when measuring the bonding strength, so that the measuring tool passes through the first measurement channel and the second measurement channel and is inserted between the first target position and the second target position, thereby generating a crack between the first wafer at the first target position and the second wafer at the second target position.

19. The semiconductor structure for measuring wafer bonding strength according to claim 18, wherein: The side wall of the first measuring channel facing away from the first side surface is an inclined side wall; the side wall of the second measuring channel facing away from the second side surface is an inclined side wall.

20. The semiconductor structure for measuring wafer bonding strength according to claim 18 or 19, characterized in that: The number of the first measurement channel and the number of the second measurement channel are both one, and the length and width of the first measurement channel are correspondingly the same as the length and width of the second measurement channel.

21. The semiconductor structure for measuring wafer bonding strength according to claim 20, wherein: The depth of the first measurement channel is 40%-85% of the thickness of the first wafer; the depth of the second measurement channel is 40%-85% of the thickness of the second wafer.

22. The semiconductor structure for measuring wafer bonding strength according to claim 20, wherein: The straight-line distance between the first target position and the center of the first wafer is ≤3 / 4 times the radius of the first wafer; the straight-line distance between the second target position and the center of the second wafer is ≤3 / 4 times the radius of the second wafer.

23. The semiconductor structure for measuring wafer bonding strength according to claim 20, wherein: The first measurement channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters; the second measurement channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters.

24. The semiconductor structure for measuring wafer bonding strength according to claim 20, wherein: The first measurement channel extends from the first side surface to the first target position along the crystal direction of the first wafer; The second measurement channel extends from the second side surface to the second target position along the crystal direction of the second wafer.

25. The semiconductor structure for measuring wafer bonding strength according to claim 18, wherein: There are multiple first target positions, and the corresponding number of first measurement channels is multiple; there are multiple second target positions, and the corresponding number of second measurement channels is multiple, the number of second target positions is equal to the number of first target positions, and the number of second measurement channels is equal to the number of first measurement channels; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide.

26. The semiconductor structure for measuring wafer bonding strength according to claim 25, wherein: The plurality of first target positions are located at different positions of the first bonding surface of the first wafer, and the plurality of first measurement channels extend from different positions of the first side surface of the first wafer to corresponding first target positions.

27. The semiconductor structure for measuring wafer bonding strength according to claim 26, wherein: Multiple second target positions are located at different positions of the second bonding surface of the second wafer, and multiple second measurement channels extend from different positions of the second side surface of the second wafer to the corresponding second target positions; when the first bonding layer of the first wafer and the second bonding layer of the second wafer are bonded together, the projections of the multiple first measurement channels and the corresponding second measurement channels on the first bonding surface coincide.

28. The semiconductor structure for measuring wafer bonding strength according to claim 27, wherein: The lengths of the plurality of first measurement channels are different, the lengths of the plurality of second measurement channels are different, and the lengths of the first measurement channels and the corresponding second measurement channels whose projections overlap on the first bonding surface are the same.

29. The semiconductor structure for measuring wafer bonding strength according to claim 18, wherein: The material of the first bonding layer is the same as that of the second bonding layer.

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