Semiconductor structure for measuring wafer bonding strength and measuring method

Abstract

The invention relates to a semiconductor structure for measuring wafer bonding strength and a measuring method, and the method comprises the steps: forming a first measurement channel which penetrates through a part of a first side surface and a part of a first bonding surface in a first wafer, and forming a second measurement channel which penetrates through a part of a second side surface and a part of a second bonding surface in a second wafer; after the first wafer and the second wafer are bonded through the first bonding layer and the second bonding layer, the projection of the first measurement channel and the projection of the second measurement channel on the first bonding surface coincide; the measuring cutter penetrates 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, and the length of the crack is measured; and calculating the bonding strength between the first target position of the first wafer and the second target position of the second wafer based on the length. Therefore, the bonding strength of the central area of the bonding surface of the bonding wafer can be measured.

Description

Technical Field

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

[0002] Wafer Bonding technology is a process technology that tightly bonds two or more wafers (usually silicon or other semiconductor materials) through physical or chemical methods, and is widely used in fields such as 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 achieve special functions.

[0003] In wafer bonding technology, the bonding strength is a very critical parameter, which is an important indicator related to the quality of bonding. If the bonding strength is small, the two bonded wafers are very likely to crack during the processing, resulting in failure.

[0004] Since testing the bonding strength is destructive, pure silicon wafers with the same thin film composition grown on the surface are used in the industry to simulate the bonding strength of real chips. Currently, the existing bonding strength testing methods include: 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 bonding strength of the edge region of the bonded wafers, and it is difficult to measure the bonding strength of the central region of the bonded wafers. Summary of the Invention

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

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

[0007] Providing a first wafer, the first wafer includes a first side surface and a first bonding surface and a first back surface that are opposite to each other;

[0008] Providing a second wafer, the second wafer includes a second side surface and a second bonding surface and a second back surface that are opposite to each other;

[0009] Forming a first measurement channel in the first wafer, the first measurement channel penetrates through a part of the first side surface and a part of the first bonding surface, and extends 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 penetrates through a part of the second side surface and a part of the second bonding surface, and extends from the second side surface to a second target position on the second bonding surface;

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

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

[0013] Bond the first bonding layer and the second bonding layer, and the projections of the first measurement channel and the second measurement channel on the first bonding surface coincide;

[0014] Provide a measuring tool. After controlling the measuring tool to pass through the first measurement channel and the second measurement channel, insert it between the first target position and the second target position, so that a crack is generated between the first wafer and the second wafer;

[0015] Measure the length of the crack, and calculate the bonding strength between the first target position and the second target position based on the length by using the crack propagation method.

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

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

[0018] wherein, Y represents the bonding 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, an infrared measuring instrument or an ultrasonic measuring instrument is used to measure the length of the crack.

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

[0021] In some embodiments of the present application, the side wall of the first measurement channel facing away from the first side is an inclined side wall; the side wall of the second measurement channel facing away from the second side is an inclined side wall.

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

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

[0024] In some embodiments of the present application, the number of the first measurement channel and the second measurement channel is one, and the length and width of the first measurement channel are correspondingly the same as those 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 linear distance between the first target position and the center of the first wafer ≤ 3 / 4 times the radius of the first wafer; the linear distance between the second target position and the center of the second wafer ≤ 3 / 4 times the radius of the second wafer.

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

[0029] In some embodiments of the present application, the number of the first target positions is multiple, and correspondingly the number of the first measurement channels is multiple; the number of the second target positions is multiple, and correspondingly the number of the second measurement channels is multiple. The number of the second target positions is equal to the number of the first target positions, and the number of the second measurement channels is equal to the number of the first measurement channels; when bonding the first bonding layer of the first wafer and the second bonding layer of the second wafer, 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, the multiple first target positions are located at different positions on the first bonding surface of the first wafer, and the multiple first measurement channels respectively extend from different positions on the first side surface of the first wafer to the corresponding first target positions.

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

[0032] In some embodiments of the present application, the lengths of a plurality of first measurement channels are different, the lengths of a plurality of second measurement channels are different, and the lengths of the first measurement channel and the corresponding second measurement channel that overlap in projection 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 measurement channel and the width of the second measurement channel, the height of the measuring tool is less than or equal to the sum of the depth of the first measurement channel and the depth of the second measurement channel, and the length of the measuring tool is greater than the length of the first measurement channel and the length of the second measurement channel.

[0034] In some embodiments of the present application, the measuring tool includes a tool tip and a tool body connected to the tool tip. The width of the tool tip is equal to the width of the tool body, and the height of the tool tip is less than the height of the tool 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.

[0035] In a second aspect, embodiments of the present application further provide a semiconductor structure for measuring the bonding strength of wafers, including:

[0036] A first wafer, the first wafer includes a first side surface and a first bonding surface and a first back surface that are opposite to each other;

[0037] A first measurement channel, located within the first wafer, the first measurement channel penetrates through a part of the first side surface and a part of the first bonding surface, and extends 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 and the first measurement channel of the first wafer;

[0039] A second wafer, the second wafer includes a second side surface and a second bonding surface and a second back surface that are opposite to each other;

[0040] A second measurement channel, located within the second wafer, the second measurement channel penetrates through a part of the second side surface and a part of the second bonding surface, and extends 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 and the second measurement channel of the second wafer;

[0042] The first bonding layer of the first wafer is bonded to the second bonding layer of the second wafer. The projections of the first measurement channel and the second measurement channel on the first bonding surface coincide. The first measurement channel and the second measurement channel are used as channels through which a measurement tool passes when measuring the bonding strength, so that after the measurement tool passes through the first measurement channel and the second measurement channel, it is inserted between the first target position and the second target position, 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 side wall of the first measurement channel facing away from the first side surface is an inclined side wall; the side wall of the second measurement channel facing away from the second side surface is an inclined side wall.

[0044] In some embodiments of the present application, the number of both the first measurement channel and the second measurement channel is 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 linear distance between the first target position and the center of the first wafer ≤ 3 / 4 times the radius of the first wafer; the linear distance between the second target position and the center of the second wafer ≤ 3 / 4 times the radius of the second wafer.

[0047] In some embodiments of the present application, the depth of the first measurement channel is 350 microns - 600 microns, and the width is 2.5 mm - 5 mm; the depth of the second measurement channel is 350 microns - 600 microns, 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 the first target positions is multiple, and correspondingly the number of the first measurement channels is multiple; the number of the second target positions is multiple, and correspondingly the number of the second measurement channels is multiple. The number of the second target positions is equal to the number of the first target positions, and the number of the second measurement channels is equal to the number of the first measurement channels. When the first bonding layer of the first wafer is bonded to the second bonding layer of the second wafer, 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, a plurality of first target positions are located at different positions on the first bonding surface of the first wafer, and a plurality of first measurement channels respectively extend from different positions on the first side surface of the first wafer to the corresponding first target positions.

[0051] In some embodiments of the present application, a plurality of second target positions are located at different positions on the second bonding surface of the second wafer, and a plurality of second measurement channels respectively 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 plurality of first measurement channels on the first bonding surface coincide with the projections of the corresponding second measurement channels.

[0052] In some embodiments of the present application, 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 channel and the corresponding second measurement channel whose projections coincide 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 can / at least have the following advantages:

[0055] In the semiconductor structure and measurement method for measuring the bonding strength of wafers in the embodiments of the present application, first, a first measurement channel is formed in the first wafer, which penetrates through a part of the first side surface and a part of the first bonding surface and extends from the first side surface to the first target position on the first bonding surface. A second measurement channel is formed in the second wafer, which penetrates through a part of the second side surface and a part of the second bonding surface and extends from the second side surface to the second target position on the second bonding surface. Then, the first wafer and the second wafer are 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, and the projections of the corresponding first target position and the second target position on the first bonding surface also coincide. The first measurement channel and the second measurement channel are jointly used as the channels through which the measurement tool passes when measuring the bonding strength. After the measurement tool passes through the first measurement channel and the second measurement channel, it 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 and calculating based on the length, the bonding strength between the first target position of the first wafer and the second target position of the second wafer is obtained. Since the corresponding first target position and the second target position when forming the first measurement channel and the second measurement channel can be any position in the middle of the first wafer and the second wafer, the bonding strength of the central region of the bonding surface of the bonded wafers, or even any position of the bonding surface, can be measured through the foregoing steps.

[0056] 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 specification, the drawings, and the claims. Description of the Drawings

[0057] To more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings required for use in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0058] Figure 1 Flow schematic diagram of a method for measuring the bonding strength of wafers provided by some embodiments of the present application;

[0059] Figure 2 Schematic structural diagram after providing the first wafer in a method for measuring the bonding strength of wafers provided by some embodiments of the present application;

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

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

[0062] Figure 5 Schematic structural diagram when forming the first protective glue on the first bonding surface of the first wafer or the second protective glue on the second bonding surface of the second wafer in a method for measuring the bonding strength of wafers provided by some embodiments of the present application;

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

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

[0065] Figure 8 Schematic structural diagram after forming the first measurement channel in the first wafer in a method for measuring the bonding strength of wafers provided by some embodiments of the present application;

[0066] Figure 9Schematic diagram of the structure after forming a second measurement channel in a second wafer in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0067] Figure 10 Schematic diagram of the structure after removing the first protective glue in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0068] Figure 11 Schematic diagram of the structure after removing the second protective glue in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0069] Figure 12 Schematic diagram of the structure after forming a first measurement channel or a second measurement channel along the crystal orientation in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0070] Figure 13 Schematic diagram of the structure after forming a plurality of first measurement channels or forming a plurality of second measurement channels in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0071] Figure 14 Schematic diagram of the structure after forming a first bonding layer on the first bonding surface of the first wafer in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0072] Figure 15 Schematic diagram of the structure after forming a second bonding layer on the second bonding surface of the second wafer in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

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

[0074] Figure 17 Schematic diagram of the structure when annealing and sintering the bonded first wafer and second wafer in a method for measuring the bonding strength of wafers provided in some embodiments of the present application;

[0075] Figure 18 Schematic diagram of the structure when measuring the bonding strength of the bonded first wafer and second wafer in a method for measuring the bonding strength of wafers provided in some embodiments of the present application.

[0076] Explanation of reference numerals:

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

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

[0079] First target position - 11; Second target position - 12; First center - 13; Second center - 14; Cleaning device - 21; Coating device - 22; Annealing and sintering device - 23; Measuring tool - 24. Detailed implementation

[0080] To facilitate the understanding of this application, the following will provide a more comprehensive description of this application with reference to relevant drawings. Embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of this application more thorough and comprehensive.

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

[0082] It should be understood that when an element or layer is referred to as "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as "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 terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types and / or parts, these elements, components, regions, layers, doping types and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or part from another element, component, region, layer, doping type or part. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type or part discussed below may be referred to as the second element, component, region, layer or part.

[0083] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. can be used herein to describe the relationship of one element or feature shown in the figure with other elements or features. It should be understood that, in addition to the orientations shown in the figure, spatial relationship terms also include different orientations of the devices during use and operation. For example, if the device in the attached drawing is flipped, an element or feature described as "under other elements" or "beneath them" or "underneath them" will be oriented "above" the other elements or features. Therefore, the exemplary terms "under" and "beneath" can include both upper and lower orientations. In addition, the device may also have other orientations (such as rotating 90 degrees or other orientations), and the spatial descriptors used herein are accordingly interpreted.

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

[0085] The structure of the embodiments of the present application should not be limited to the specific shapes shown in the drawings of the specification, but includes shape deviations caused by, for example, manufacturing techniques.

[0086] It can be understood that in the drawings of the specification of the present application, adjacent film layers with the same film layer material in some figures are drawn as 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., bonding strength). Its process generally includes: inserting a thin blade from the side into the bonding interface of two bonded wafers, separating a part of the two bonded wafers, generating a crack (or gap) between the two wafers, then measuring the crack length using infrared detection or ultrasonic detection methods, and finally calculating the bonding strength of the two wafers based on the crack length.

[0088] Currently, due to the thinness of the blade, it is prone to deformation and the insertion depth is limited. Therefore, the existing crack propagation method can generally only measure the bonding strength of the edge area of the bonded wafer (at a position 2 cm - 3 cm away from the side surface of the bonded wafer), and it is impossible to measure the bonding strength of the central area of the bonded wafer (the bonded wafer generally includes a central area and an edge area surrounding the central area). Moreover, the deeper the blade is inserted from the side surface of the bonded wafer into the bonding interface, the greater the difficulty, and the friction force will cause damage to the blade, resulting in thickness changes and inaccurate measurement. In addition, when the blade is inserted too deep from the side surface of the bonded wafer into the bonding interface, it is easy to cause the wafer to break.

[0089] To this end, the embodiments of the present application first provide a method for measuring the bonding strength of wafers. Figure 1 It is a schematic flow chart of a method for measuring the bonding strength of wafers provided by some embodiments of the present application.

[0090] Refer to Figure 1 , the method for measuring the bonding strength of wafers includes the steps:

[0091] Step S101, provide a first wafer, the first wafer includes a first side surface and a first bonding surface and a first back surface opposite to each other; provide a second wafer, the second wafer includes a second side surface and a second bonding surface and a second back surface opposite to each other;

[0092] Step S102, form a first measurement channel in the first wafer, the first measurement channel penetrates through part of the first side surface and part 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, form a second measurement channel in the second wafer, the second measurement channel penetrates through part of the second side surface and part of the second bonding surface, and extends from the second side surface to a second target position on the second bonding surface;

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

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

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

[0097] Step S107, provide a measuring tool, control the measuring tool to pass through the first measurement channel and the second measurement channel, and then insert it 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, measure the length of the crack, and calculate the bonding strength between the first target position and the second target position based on the length by using the crack propagation method.

[0099] The following combines the attached Figure 2 - attached Figure 18 Describe in detail the specific process of the foregoing method for measuring the wafer bonding strength.

[0100] First, in combination with the reference Figure 1 and Figure 2 , perform step S101 to provide the 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 opposite to each other; provide the 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 bonding strength measurement subsequently. In some embodiments, since the subsequent measurement of the bonding strength is destructive, in order to save costs, the first wafer 101 and the second wafer 201 use bare wafers, and then a first bonding layer is formed 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 cost, semiconductor devices or integrated circuits corresponding to the structures in real chips 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 respectively used as the first bonding surface and the second bonding surface.

[0102] The first wafer 101 has a first bonding surface and a first back surface that are opposite to each other, and the first side surface is located between the first bonding surface and the first back surface. As Figure 2 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 also has a first notch 102. On the one hand, the first notch 102 can be used to mark the crystal orientation of the first wafer 101, such as <100>, <110>, <111>, etc. On the other hand, it can be used as a positioning mark and an alignment mark in the subsequent process.

[0103] The second wafer 201 has a second bonding surface and a second back surface that are opposite to each other, and the second side surface is located between the second bonding surface and the second back surface. As 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. On the one hand, the second notch 202 can be used to mark the crystal orientation of the second wafer 201, such as <100>, <110>, <111>, etc. On the other hand, it can be used as a positioning mark and an alignment mark in subsequent process steps.

[0104] In some embodiments, the size of the first wafer 101 is the same as that 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 that 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 that of the second wafer 201. For example, both can be silicon materials, or both can also 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 in different situations, one or several of the size of the first wafer 101 and the second wafer 201, the thickness of the first wafer 101 and the second wafer 201, and the material of the first wafer 101 and the second wafer 201 can be different. For example, when the size of the first wafer 101 is the same as that of the second wafer 201 and the material of the first wafer 101 is the same as that of the second wafer 201, the thickness of the first wafer 101 can be different from that of the second wafer 201. Another example is that when the size of the first wafer 101 is the same as that of the second wafer 201 and the thickness of the first wafer 101 is the same as that of the second wafer 201, the material of the first wafer 101 can be different from that of the second wafer 201.

[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 close to the first side surface, or the region of the second wafer 201 close to the second side surface. In one example, the edge region can be the region of the first wafer within a distance less than 3 microns from the first side surface, or the region of the second wafer within a distance less than 3 microns from the second side surface. After bonding the first wafer 101 and the second wafer 201, the corresponding bonding surfaces of the two wafers can include a central region and an 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, refer to Figure 3, further comprising: cleaning the first wafer 101 and the second wafer 201 to remove contaminants on the surfaces of the first wafer 101 and the second wafer 201, which is beneficial to improving the bonding strength between the first wafer 101 and the second wafer 201 in the subsequent process. In one example, a cleaning device or the 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, refer to Figure 6 , further comprising: forming a first protective glue 103 on the first bonding surface of the first wafer 101. When the first measurement channel is formed in the first wafer 101 subsequently, the first protective glue 103 can prevent the generated debris from contaminating or damaging the first bonding surface of the first wafer 101. The first protective glue 103 can be a photoresist or other glue that is easy to form and easy to clean and remove. In one example, refer to Figure 5 , and a coating device or coating equipment is used to form the first protective glue 103 by a spin coating process.

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

[0110] Then, referring to Figure 1 and Figure 8 , step S102 is performed to form a first measurement channel 104 in the first wafer 101. The first measurement channel 104 penetrates through part of the first side surface and part of the first bonding surface and extends from the first side surface to the first target position 11 on the first bonding surface; refer to Figure 10 , after forming the first measurement channel 104, the first protective glue 103 is removed (refer to Figure 8 ).

[0111] In this application, a first measurement channel 104 that penetrates through part of the first side surface and part of the first bonding surface and extends from the first side surface to the first target position on the first bonding surface is pre-formed in the first wafer 101. Subsequently, a second measurement channel 204 that penetrates through part of the second side surface and part of the second bonding surface and extends from the second side surface to the second target position on the second bonding surface will also be formed in the second wafer 201 (refer to Figure 11), after the first wafer 101 and the second wafer 201 are bonded through the first bonding layer 105 and the second bonding layer 205 subsequently (refer to Figure 16 ), the projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface coincide, and the projections of the corresponding first target position 11 and the second target position 12 on the first bonding surface also coincide. The first measurement channel 104 and the second measurement channel 204 are jointly used as the channels through which the measuring tool 24 (refer to Figure 18 ) passes when measuring the bonding strength. After the measuring tool 24 passes through the first measurement channel 104 and the second measurement 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. Since the corresponding first target position 11 and the second target position 12 when forming the first measurement channel 104 and the second measurement channel 204 can be the central region of the bonding surface of the first wafer 101 and the second wafer 201, or even any position of the entire bonding surface, the bonding strength of the central region of the bonding surface of the bonded wafers, or even any position of the entire bonding surface, can be measured through the foregoing steps.

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

[0113] In some embodiments, the side wall of the first measurement channel 104 facing away from the first side is an inclined side wall, and the inclined direction of the inclined side wall is inclined in a direction away from the first side of the first wafer 101 that is penetrated. Formation of the inclined side wall: When using the grinding wheel cutting process, when the grinding wheel cuts the first wafer 101, the side wall of the first measurement channel 104 facing away from the first side will be inclined. When the side wall of the first measurement channel 104 facing away from the first side is an inclined side wall, subsequently in the second wafer 201 (refer to Figure 11 ) the formed second measurement channel 204 (refer to Figure 11) is also an inclined sidewall. After the first wafer 101 and the second wafer 201 are bonded correspondingly, the first measuring channel 104 and the second measuring channel 204 are jointly used as a channel for the measuring tool to pass through. The inclined sidewall of the first measuring channel 104 that is away from the first side and the inclined sidewall of the second measuring channel 204 that is away from the second side can adapt to the shape of the tip of the measuring tool when they cooperate with each other (the measuring tool generally may include a tip and a blade body connected to the tip, and the tip may include a first blade face and a second blade face that are away from each other, and the first blade face and the second blade face are both inclined blade faces, that is, the vertical distance between the first blade face and the second blade face gradually decreases from the front end of the tip away from the blade body to the direction of the blade body) 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 beneficial to improving the accuracy of the measurement. It should be noted that, in other embodiments, according to measurement requirements, the side wall of the first measurement channel 104 that is away from the first side surface may also be in 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 10, the 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%, 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 measuring the bonding strength subsequently, 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, when designing the corresponding measuring tool, the measuring tool can maintain a relatively large height or thickness, which can improve the rigidity of the measuring tool and prevent the tool from deforming during the measurement of the bonding strength and 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, after the subsequent bonding of the first wafer 101 and the second wafer 201, their projections on the first bonding surface also coincide. The linear distance d1 between the first target position 11 and the center of the first wafer 101 (the first center 13, reference Figure 13 ) is d1 ≤ 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 close to the center. Therefore, after the subsequent bonding of the first wafer 101 and the second wafer 201, it is possible to measure the bonding strength of the central region of the bonding surface of the bonded wafers or even any position on the bonding surface. 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 - 600 μm, specifically it can be 350 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, the width W1 is 2.5 mm - 5 mm, specifically it can be 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, and the length L1 of the first measurement channel 104 varies according to the different first target positions 11.

[0116] Next, with reference to Figure 1 and Figure 9 , perform step S103 to form a second measurement channel 204 in the second wafer 201. The second measurement channel 204 penetrates part of the second side surface and part of the second bonding surface and extends from the second side surface to the second target position 12 on the second bonding surface; reference Figure 11 , after forming the second measurement channel 204, remove the second protective glue 203 (reference Figure 9 ).

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

[0118] In some embodiments, the second measurement channel 204 is formed in the second wafer 201 using a grinding wheel cutting process. Since the formed second measurement channel 204 is generally relatively deep, the grinding wheel cutting process can form the second measurement channel 204 quickly and accurately. In some embodiments, after the grinding wheel cutting process, cleaning is performed to remove cutting residues and the second protective glue 203. The cleaning can use a wet cleaning or a dry cleaning process.

[0119] In some embodiments, the side wall of the second measurement channel 204 facing away from the second side is an inclined side wall, and the inclined direction of the inclined side wall is inclined in a direction away from the second side of the second wafer 201 that is penetrated. Formation of the inclined side wall: When using the grinding wheel cutting process to cut the second wafer 201, the side wall of the second measurement channel 204 facing away from the second side will be in an inclined shape. It should be noted that in other embodiments, according to the measurement requirements, the side wall of the second measurement channel 204 facing away from the second side can also be of other shapes.

[0120] In some embodiments, the number of the first measurement channel 104 and the second measurement channel 204 formed in the subsequent second wafer 201 is one each, 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 should be such that it does not affect the 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%, 85% of the thickness of the second wafer 201. At the aforementioned specific depths, on the one hand, it will not affect the subsequent bonding of the second wafer and the first wafer. On the other hand, when measuring the bonding strength subsequently, the height or thickness of the measurement tool used needs to be adapted to the total depth of the second measurement channel and the first measurement channel. When the second measurement channel 204 is within this depth range, when designing the measurement tool accordingly, the measurement tool can maintain a relatively large height or thickness, which can improve the rigidity of the measurement tool and prevent the tool from deforming during the bonding strength measurement and affecting 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, after the subsequent bonding of the second wafer 201 and the first wafer 101, their projections on the first bonding surface also coincide. The second target position 12 and the center of the second wafer 201 (the second center 14, reference Figure 13The linear distance d2 of ) ≤ 3 / 4 times the radius r2 of the second wafer 201, that is, the second target position can be any position near the center of the second bonding surface of the second wafer 201. Therefore, after the second wafer 201 and the first wafer 101 are bonded subsequently, the bonding strength at any position in the central region of the bonded wafers can be measured. In a specific example, when the thickness of the second wafer 201 is 750 microns ± 50 microns, the depth of the second measurement channel 204 is 350 microns - 600 microns, specifically it can be 350 microns, 350 microns, 400 microns, 450 microns, 500 microns, 550 microns, 600 microns, and the width is 2.5 mm - 5 mm, specifically it can be 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm. The length L1 of the second measurement channel 204 varies according to the different second target positions 12.

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

[0123] In some embodiments, referring to Figure 12 , when forming the first measurement channel 104 and the second measurement channel 204, the first measurement channel 104 can be formed by using a grinding wheel cutting process along the crystal orientation of the first wafer 101 (such as crystal orientation <100> or crystal orientation <110>), that is, the formed 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 can be formed by using a grinding wheel cutting process along the crystal orientation of the second wafer 201 (such as <100> crystal orientation or <110> crystal orientation), that is, the formed 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. Since the Young's modulus of different crystal orientations on the wafer is different, for example, the Young's modulus of the <110> crystal orientation is 1.70 * 10 11 pa, and the Young's modulus of the <100> crystal orientation is 1.30 * 10 11 pa. When both the first measurement channel 104 and the second measurement channel 204 extend along the crystal orientation, when measuring the bonding strength subsequently, 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, thereby improving the accuracy of the bonding strength measurement. It should be noted that for a clearer explanation, Figure 12 the wafer shown in

[0124] In some embodiments, referring to Figure 13, the number of the first target positions 11 can be multiple, such as 2 - 6, correspondingly, the number of the first measurement channels 104 is multiple, such as 2 - 6, and the number of the first measurement channels 104 is equal to the number of the first target positions; the number of the second target positions 12 is multiple, 2 - 6, correspondingly, the number of the second measurement channels 204 is multiple, 2 - 6, and the number of the second measurement channels 204 is equal to the number of the second target positions 12, and the number of the second target positions 12 is equal to the number of the first target positions 11, and the number of the second measurement channels 204 is equal to the number of the first measurement channels 104; when bonding the first bonding layer 105 of the first wafer 101 and the second bonding layer 205 of the second wafer 201, 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 wafers, different first measurement channels 104 and the corresponding second measurement channels 204 can provide channels for measuring the bonding strength at different positions, so that the bonding strength at different positions in the central area of the bonded wafers can be measured. It should be noted that, for a clearer explanation, Figure 13 the wafer shown in

[0125] In one embodiment, with continued reference to Figure 3 , the multiple first target positions 11 are located at different positions on the first bonding surface of the first wafer 101, and the multiple first measurement channels 104 respectively extend from different positions on the first side surface of the first wafer 101 to the corresponding first target positions 11. Correspondingly, the multiple second target positions 12 are located at different positions on the second bonding surface of the second wafer 201, and the multiple second measurement channels 204 respectively extend from different positions on the second side surface of the second wafer 201 to the corresponding second target positions 12; and the lengths of the multiple first measurement channels 104 are different, the lengths of the corresponding multiple second measurement channels 204 are different, and the lengths of the first measurement channel 104 and the corresponding second measurement channel 204 whose projections on the first bonding surface coincide are the same. Subsequently, after bonding the first wafer 101 and the second wafer 201, the measurement channels formed by different first measurement channels 104 and the corresponding second measurement channels 204 can have different distances from the center of the circle (the first center 13 or the second center 14), so that the bonding strength at positions with different distances from the center of the circle (the first center 13 or the second center 14) of the bonded wafers can be measured.

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

[0127] The materials of the first bonding layer 105 and the second bonding layer 205 are the same. The thicknesses of the first bonding layer 105 and the second bonding layer 205 are much smaller than the thicknesses of the first wafer 101 or the second wafer 201. The thicknesses of the first wafer 101 or the second wafer 201 are in the order of several hundred micrometers (e.g., 600 micrometers - 800 micrometers), while the thicknesses of the first bonding layer 105 and the second bonding layer 205 are in the nanometer range. In some embodiments, the thicknesses of the first bonding layer 105 and the second bonding layer 205 are 5nm - 50nm. In some embodiments, the materials of the first bonding layer 105 and the second bonding layer 205 are silicon oxide or silicon carbonitride.

[0128] In a specific embodiment, the materials of the first bonding layer 105 and the second bonding layer 205 are 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 second bonding layer 205 will correspondingly cover the first bonding surface and the second bonding surface, and the openings of the first measurement channel 104 located on the first bonding surface will not form the first bonding layer material (silicon oxide material), and the openings of the second measurement channel 204 located on the second bonding surface will not form the second bonding layer material (silicon oxide material). However, a thinner silicon oxide material will be formed on the inner walls of the first measurement channel 104 and the second measurement channel 204 (not shown in the figure). The silicon oxide on the inner wall surfaces of the first measurement channel 104 and the second measurement channel 204 is very thin and 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.

[0129] In another specific embodiment, the materials of the first bonding layer 105 and the second bonding layer 205 are silicon carbonitride, 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 second bonding layer 205 will correspondingly cover the first bonding surface and the second bonding surface. Since the depths of the first measurement channel 104 and the second measurement channel 204 are much larger than the thicknesses of the formed first bonding layer 105 and second bonding layer 205, during the chemical vapor deposition process, the openings of the first measurement channel 104 located on the first bonding surface may be blocked by the first bonding layer material (silicon carbonitride material), and the openings of the second measurement channel 204 located on the second bonding surface may also be blocked by the second bonding layer material (silicon carbonitride material). However, the silicon nitride materials are all very thin and thus 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 the first bonding layer 105 and the second bonding layer 205 are formed, a chemical mechanical polishing process may 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 may be plasma-activated to activate the surfaces of the first bonding layer 105 and the second bonding layer 205, and deionized water cleaning may 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] Reference Figure 1 And in combination with reference Figure 16 , step S106 is performed to bond the first bonding layer 105 and the second bonding layer 205, and the projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface coincide.

[0133] After aligning the first wafer 101 and the second wafer 201, 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 the first wafer 101 and the second wafer 201 are aligned and bonded, it further includes performing an annealing superjunction process on the first wafer 101 and the second wafer 201, so as to form a covalent bond permanent bond between the first bonding layer 105 and the second bonding layer 205. In one example, the annealing superjunction process is performed in an annealing superjunction device or equipment, the temperature range of the annealing superjunction process is 280 degrees Celsius - 320 degrees Celsius, and the time range of the annealing superjunction process is 1.5 hours - 2.5 hours.

[0135] Next, in combination with reference Figure 1 , Figure 16 and Figure 18 , step S107 is performed to provide a measuring tool 24. After controlling the measuring tool 24 to pass through the first measurement channel 104 and the second measurement channel 204 (reference Figure 16 ), it is inserted between the first target position 11 and the second target position 12, so that a crack 15 is generated between the first target position 11 of the first wafer 101 and the second target position 12 of the second wafer 201 (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 depth of the first measuring channel 104 and the depth of the second measuring channel 204, and the length of the measuring tool 24 is greater than the length of the first measuring channel 104 and the length of the second measuring channel 204. In an example, when the width of the first measuring channel 104 and the second measuring channel 204 is 3 mm and the sum of the depth of the first measuring channel 104 and the depth of the second measuring channel 204 is 0.8 mm, the width of the measuring tool 24 can be 2 mm, the height can be 0.7 mm, and the length is greater than the length of the first measuring channel 104 and the length of the second measuring channel 204.

[0137] In some embodiments, the measuring tool 24 may include a blade body with the tips of the blades connected. The width of the tip of the blade is equal to the width of the blade body, and the height of the tip of the blade 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 tip of the blade is inserted between the first target position 11 and the second target position 12 first, and then the blade body is inserted between the first target position 11 and the second target position 12. In some embodiments, the tip of the blade may include a first blade surface and a second blade surface that face away from 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 in the direction from the front end away from the blade body to the blade body.

[0138] In some embodiments, the measuring tool 24 can be inserted manually by a person or automatically by a related device.

[0139] Finally, continue to refer to Figure 1 and Figure 18 , perform step S108 to 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 the crack propagation method.

[0140] In some embodiments, the length of the crack can be measured by an infrared measurement method or an ultrasonic measurement method, and specifically, an infrared measuring instrument or an ultrasonic measuring instrument can be used. It should be noted that Figure 18 the crack 15 shown in

[0141] is the corresponding light and dark stripes obtained when measuring the real crack between the first wafer 101 and the second wafer 201 using an infrared measuring instrument. In one embodiment, calculating the bonding strength at the first target position 11 and the second target position 12 based on the length using the crack propagation method includes: calculating the bonding strength through 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 bonding 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 calculation of the bonding strength can 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, t b represents the height of the measuring tool 24, and L represents the length of the crack 15.

[0146] The embodiments of the present application also provide a semiconductor structure for measuring the bonding strength of wafers. Refer to Figure 16 , including:

[0147] The first wafer 101, the first wafer 101 includes a first side surface and a first bonding surface and a first back surface that are opposite to each other;

[0148] The first measurement channel 104, located inside the first wafer 101, the first measurement channel 104 penetrates through a part of the first side surface and a part of the first bonding surface, and extends from the first side surface to the first target position 11 on the first bonding surface;

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

[0150] The second wafer 201, 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;

[0151] The second measurement channel 204 is located within the second wafer 201. The second measurement channel 204 penetrates through a part of the second side surface and a part of the second bonding surface, and extends from the second side surface to the second target position 12 on the second bonding surface;

[0152] The second bonding layer 205 is located on the second bonding surface of the second wafer 201 and on 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. The projections of the first measurement channel 104 and the second measurement channel 204 on the first bonding surface coincide. The first measurement channel 104 and the second measurement channel 204 form a measurement channel for use as a channel through which the measurement tool 24 (reference Figure 18 ) passes when measuring the bonding strength, so that the measurement tool 24 passes through the first measurement channel 104 and the second measurement channel 204 and then inserts between the first target position 11 and the second target position 12, generating a crack 15 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 side wall of the first measurement channel 104 facing away from the first side surface is an inclined side wall; the side wall of the second measurement channel 204 facing away from the second side surface is an inclined side wall.

[0155] In some embodiments, the number of both the first measurement channel 104 and the second measurement channel 204 is 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 wafer with a diameter of 100 mm (4 inches), the thickness is usually about 525 µm; for a wafer with a diameter of 150 mm (6 inches), the thickness is usually about 675 µm; for a wafer with a diameter of 200 mm (8 inches), the thickness is usually about 725 µm; for a wafer with a diameter of 300 mm (12 inches), the thickness is usually about 775 µm. The depth of the first measurement channel and the second measurement channel must be such that it does not affect the bonding of the first wafer and the second wafer.

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

[0158] In some embodiments, the depth of the first measurement channel 104 is 350 microns - 600 microns, and the width is 2.5 mm - 5 mm; the depth of the second measurement channel 204 is 350 microns - 600 microns, and the width is 2.5 mm - 5 mm.

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

[0160] In some embodiments, the number of the first target positions 11 is multiple, and the corresponding number of the first measurement channels 104 is multiple; the number of the second target positions 12 is multiple, and the corresponding number of the second measurement channels 204 is multiple. The number of the second target positions 12 is equal to the number of the first target positions 11, and the number of the second measurement channels 204 is equal to the number of the first measurement channels 104. When bonding the first bonding layer 105 of the first wafer 101 and the second bonding layer 205 of the second wafer 201 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 multiple first target positions 11 are located at different positions on the first bonding surface of the first wafer 101, and the multiple first measurement channels 104 respectively extend from different positions on the first side surface of the first wafer 101 to the corresponding first target positions 11.

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

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

[0164] In some embodiments, the materials of the first bonding layer 105 and the second bonding layer 205 are silicon oxide or silicon carbonitride.

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

[0166] Within the description of this specification, the descriptions referring to terms such as "some embodiments", "other embodiments", "ideal embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0167] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0168] The above embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed. However, it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of the patent of this application shall be subject to the appended claims.

Claims

1. A method for measuring wafer bonding strength, characterized in that: include: Providing a first wafer, wherein the first wafer comprises 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 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; forming a second measurement channel in the second wafer, wherein the second measurement channel 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; 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 that a crack is generated 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, characterized in that: 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 by 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: Before forming a 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 glue is formed on the second bonding surface, and after forming the second measurement channel, the second protective glue is removed.

7. The method for measuring wafer bonding strength according to claim 1, 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.

8. The method for measuring wafer bonding strength according to claim 7, characterized in that: 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, characterized in that: 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, characterized in that: The first measuring channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters; the second measuring 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, characterized in that: The first measurement channel extends from the first side surface to the first target position along the crystal direction of the first wafer; and 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, characterized in that: The number of the first target positions is multiple, and the corresponding number of the first measurement channels is multiple; the number of the second target positions is multiple, and the corresponding number of the second measurement channels is multiple, the number of the second target positions is equal to the number of the first target positions, and the number of the second measurement channels is equal to the number of the 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, characterized in that: 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 respectively.

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

15. The method for measuring wafer bonding strength according to claim 14, characterized in that: 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, characterized in that: 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, characterized in that: The measuring tool comprises a tool tip and a tool body connected to the tool tip, the width of the tool tip is equal to the width of the tool body, and the height of the tool tip is less than the height of the tool 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, the 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 is located in the first wafer, the first measurement channel runs 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 first bonding layer, located on the first bonding surface of the first wafer and the first measurement channel; 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; A second measurement channel is located 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 of the second bonding surface; a second bonding layer, located on a second bonding surface and a second measurement channel of the second wafer; The first bonding layer of the first wafer is bonded to the second bonding layer of the second wafer, 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 through which a measuring tool passes when measuring the bonding strength, so that the measuring tool passes through the first measurement channel and the second measurement channel and then 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The first measuring channel has a depth of 350 micrometers to 600 micrometers and a width of 2.5 millimeters to 5 millimeters; the second measuring 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, characterized in that: 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, characterized in that: 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, characterized in that: 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 respectively.

27. The semiconductor structure for measuring wafer bonding strength according to claim 26, characterized in that: 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, characterized in that: 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, characterized in that: The material of the first bonding layer is the same as that of the second bonding layer.

Images