Bonding Fixture for Wafer Bonding, Bonding Equipment and Method Using the Same

Abstract

A bonding fixture for wafer bonding, a bonding device and method using the same, belonging to the technical field of semiconductor devices. The bonding fixture (100) for wafer (102) bonding includes a tray (1), a limiting block (2), a rigid cushion block (3) and a baffle (4); radial and vertical positioning of the wafer is achieved through the bonding fixture (100). Through the bonding fixture (100), bonding device (101) and method for wafer bonding using the bonding device (101) of the present invention, the position of the wafer is positioned and the wafer terminals are protected from pressure.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a bonding fixture for wafer bonding and a bonding device and method using the same. Background Art

[0002] Integrated gate-commutated thyristor (IGCT) devices are fully controlled power devices with the largest single-tube capacity. Due to their superior performance such as large capacity, fast switching speed, low switching loss and high di / dt tolerance, they are widely used in fields such as DC transmission, smart grid, power converters, and power inverters. They have broad prospects and huge room for future development.

[0003] The IGCT device is mainly composed of a GCT element and a driving circuit board connected to its lead-out electrode, wherein the GCT element is the core component of the IGCT device. The GCT element is mainly composed of a semiconductor chip and a packaging shell. The packaging shell includes a shell base, a gate assembly, a cathode sheet, an anode sheet, a shell cover, etc., wherein the gate assembly is mainly composed of a gasket, an elastic support, an insulating seat and a gate lead-out ring.

[0004] The existing packaging structure is a five-layer structure of anode copper electrode-anode molybdenum sheet-silicon chip-cathode molybdenum sheet-cathode copper electrode, and the electrical connection is achieved through mechanical pressure rigid contact. With the continuous improvement of the power level of IGCT devices, higher requirements are placed on the thermal resistance of device packaging. Nanosilver low-temperature bonding technology can significantly reduce the thermal resistance of the device due to its excellent heat transfer performance, and thus has the potential to be applied to the wafer packaging of power devices such as GCT.

[0005] Compared with the existing nanosilver low-temperature bonding technology, the shortcomings of its bonding fixture are mainly:

[0006] 1. Existing bonding fixtures are suitable for small chip conditions, and there is no mature solution for large-area wafer bonding above 6 inches;

[0007] 2. The existing bonding process is carried out in air or nitrogen atmosphere, and does not have formic acid reduction function, which cannot meet the bonding requirements of easily oxidized samples. Summary of the invention

[0008] The purpose of the present invention is to provide a novel bonding fixture for wafer bonding, which can realize wafer positioning and protect the wafer terminal from pressure.

[0009] In order to achieve the above-mentioned purpose, as the first aspect of the present invention, a bonding fixture for wafer bonding is provided, wherein the upper and lower surfaces of the wafer respectively have symmetrical flanges extending upward and downward at the edge portions. The bonding fixture comprises a tray, a limit block, a rigid pad, and a baffle; the wafer is arranged on the tray, and the anode molybdenum sheet to be bonded is located between the tray and the wafer; the limit block is arranged on the tray and limits the wafer in the radial direction of the wafer, the tray limits the limit block in the radial direction of the wafer, the rigid pad is arranged above the upper surface of the wafer, the cathode molybdenum sheet to be bonded is located between the upper surface of the wafer and the rigid pad, the baffle is arranged to cover the limit block and the flange of the wafer and limit the rigid pad in the radial direction of the wafer, and the baffle is detachably connected to the tray so as to limit in the vertical direction.

[0010] Preferably, the tray, the limit block, the rigid pad and the baffle are all substantially cylindrical, and the central axes of the tray, the limit block, the rigid pad and the baffle are in the same straight line as the central axis of the wafer.

[0011] Preferably, the flange on the lower surface of the wafer and the lower surface of the limiting block are both in contact with the upper surface of the tray, and the flange on the upper surface of the wafer and the upper surface of the limiting block are at the same height.

[0012] Preferably, the central portion of the limiting block has an opening to form an inner wall of the limiting block, and the inner wall of the limiting block contacts the side wall of the wafer.

[0013] Preferably, the rigid pad includes a base and a boss above the base, and the size of the boss is smaller than the size of the base in the radial direction of the wafer; the base is arranged above the cathode molybdenum sheet, the upper surface of the base is at the same height as the flange of the upper surface of the wafer, and the upper surface of the boss is slightly lower than the upper surface of the main body.

[0014] Preferably, the baffle includes a main body, a vertical wall and a lower flange, the central part of the main body has an opening to form an inner wall of the main body, the inner wall of the main body contacts the side wall of the boss of the rigid pad; the lower surface of the lower flange contacts the tray, the main body is connected to the lower flange as a whole through the vertical wall, the inner side of the vertical wall facing the wafer contacts the outer wall of the limit block, and the lower flange is detachably connected to the tray.

[0015] Preferably, the tray has a convex portion extending upward from the edge portion on the upper surface, the upper surface of the convex portion contacts the lower surface of the lower flange of the baffle, and the wall portion of the convex portion facing the wafer contacts the outer wall of the limiting block.

[0016] Preferably, the bonding fixture also includes an elastic membrane and a pressure ring; the shape and size of the elastic membrane are set to correspond to the baffle, so that the elastic membrane simultaneously covers the upper surface of the boss of the rigid pad and the upper surface of the baffle; the pressure ring is annular and is arranged above the lower flange of the baffle so that it can be detachably connected to the lower flange and the convex part of the tray, thereby fixing the elastic membrane at the edge; the central axis of the pressure ring, the central axis of the elastic membrane and the central axis of the wafer are on the same straight line.

[0017] Preferably, the elastic membrane is provided with a through hole.

[0018] Preferably, the limiting block is provided with a flow channel and a hole, the flow channel is arranged inside the limiting block, the hole is arranged to penetrate the limiting block in the radial direction of the limiting block, and the flow channel is communicated with the hole.

[0019] According to another aspect of the present invention, there is also provided a bonding device for wafer bonding, comprising the above-mentioned bonding fixture and a pressing head, wherein the pressing head comprises an upper and a lower pressing head, and the bonding fixture is arranged between the pressing heads.

[0020] Preferably, the pressure head at the upper end comprises a rigid frame and an elastic body.

[0021] Preferably, the rigid frame is in a groove shape, and the elastic body is arranged in the groove.

[0022] Preferably, the elastomeric body is mounted within the rigid frame and extends slightly beyond the rigid frame.

[0023] According to one aspect of the present invention, a method for wafer bonding is also provided, the method using the above-mentioned bonding equipment, the method comprising: step 1, preheating the upper pressure head; step 2, setting the limit block on the tray; step 3, installing the anode molybdenum sheet and wafer to be bonded so that the limit block limits the radial direction of the wafer; step 4, installing the cathode molybdenum sheet to be bonded above the wafer; step 5, installing the rigid pad above the cathode molybdenum sheet; step 6, installing the baffle plate to limit the rigid pad in the radial direction of the wafer; step 7, installing the elastic membrane; step 8, installing the pressure ring, detachably connecting the pressure ring and the baffle plate to the tray, fixing the elastic membrane to limit it in the vertical direction; step 9, installing the bonding fixture in the bonding equipment, located between the pressure heads; step 10, passing the reducing atmosphere into the bonding fixture during the preheating and bonding process to perform the bonding operation.

[0024] Based on the above technical solutions, it can be known that the present invention has at least one of the following beneficial effects compared with the prior art.

[0025] (1) The bonding fixture is optimized to meet the requirements of wafer bonding;

[0026] (2) Propose an elastomer structure to improve bonding yield;

[0027] (3) It has a flow channel design to meet the requirements of reducing atmosphere introduction and improve the bonding quality.

[0028] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0030] Figure 1 is a schematic diagram of a bonding apparatus including a bonding fixture according to an embodiment of the present invention;

[0031] Figure 2 is a comparative schematic diagram of wafers after bonding using a conventional bonding device and the bonding device of the present invention;

[0032] Figure 3 is an exploded view of a pressing head according to an embodiment of the present invention;

[0033] Figure 4 is an exploded view of a bonding fixture according to an embodiment of the present invention;

[0034] Figure 5 is a cross-sectional view of a bonding fixture according to an embodiment of the present invention, wherein the cathode molybdenum sheet is not shown;

[0035] Figure 6 is a cross-sectional view of the wafer;

[0036] Figure 7 is a schematic diagram of a limit block according to an embodiment of the present invention;

[0037] Figure 8 is a schematic perspective view of a tray according to an embodiment of the present invention;

[0038] Fig. 9 is a schematic perspective view of a baffle according to an embodiment of the present invention;

[0039] Fig.10 is a schematic perspective view of a rigid spacer according to an embodiment of the present invention;

[0040] Fig.11 is a schematic perspective view of an elastic membrane according to an embodiment of the present invention;

[0041] Fig.12 is a schematic perspective view of a pressure ring according to an embodiment of the present invention.

[0042] List of reference numerals:

[0043] 1. Tray; 12. convex part; 2. limit block; 21. hole; 22. flow channel; 3. rigid pad; 31. boss; 32. base; 4. baffle; 41. main body; 42. vertical wall; 43. lower flange; 5. elastic membrane; 6. pressure ring; 100. bonding fixture; 101. bonding equipment; 102. wafer; 103. pressure head; 104. rigid frame; 105. elastomer; 106. flange; 107. upper surface; 108. lower surface; 109. anode molybdenum sheet. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0045] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in detail in conjunction with the accompanying drawings below. Note that the embodiments can be implemented in multiple different forms. A person of ordinary skill in the art can easily understand the fact that the methods and contents can be transformed into various forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the contents described in the following embodiments. In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include at least one of the features.

[0048] In the description of the present application, “plurality” means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0052] According to the implementation manner of the present invention, the present invention adopts the following technical solutions.

[0053] like Figure 1 As shown, the bonding device 101 includes two upper and lower pressing heads 103 and a bonding fixture 100 disposed between the pressing heads 103. In the conventional bonding device 101, the pressing head 103 is a rigid pressing head 103. In the embodiment of the present application, the upper pressing head 103 is replaced with an elastic pressing head 103. Figure 3As shown, in an embodiment of the present application, the elastic pressure head 103 includes a rigid frame 104 and an elastomer 105. The rigid frame 104 is in a groove shape so as to increase the bonding strength between the elastomer 105 and the frame. The elastomer 105 is arranged in the groove. Preferably, the elastomer 105 can be a silicone elastic material, which is formed by injecting the silicone material into the rigid frame 104 and then curing it. The elastomer 105 is installed in the rigid frame 104 and slightly extends out of the rigid frame 104 so as to provide elastic deformation space for the elastomer 105. Preferably, the protruding size of the elastomer 105 is in the range of ≤2mm to ensure the service life of the elastomer 105.

[0054] By using the elastic pressure head 103 of the present application and the bonding fixture 100 described below, the packaging structure obtained after bonding is Figure 2 Shown in. Figure 2 In the figure, the right side is a packaging structure obtained by the bonding fixture 100 of the present application and the elastic pressing head 103, and the left side is a packaging structure obtained by the traditional bonding device 101. The bonding effect of the wafer 102 obtained by using the bonding device 101 of the present application is better.

[0055] like Figure 4 and Figure 6 As shown in FIG. 1 , the upper surface 107 and the lower surface 108 of the wafer 102 respectively have symmetrical flanges 106 extending upward and downward at the edge. The cathode molybdenum sheet and the anode molybdenum sheet 109 to be bonded are respectively disposed on the upper surface 107 and the lower surface 108 of the wafer 102.

[0056] like Figure 4 and Figure 5 As shown in , according to an embodiment of the present application, a bonding fixture 100 for bonding a wafer 102 includes a tray 1, a stopper 2, a rigid pad 3, and a baffle 4. The wafer 102 is set on the tray 1, and the anode molybdenum sheet 109 to be bonded is located between the tray 1 and the wafer 102;

[0057] The limiting block 2 is arranged on the tray 1 and limits the position of the wafer 102 in the radial direction of the wafer 102. The tray 1 limits the limiting block 2 in the radial direction of the wafer 102.

[0058] The rigid pad 3 is disposed above the upper surface 107 of the wafer 102, and the cathode molybdenum sheet to be bonded is located between the upper surface 107 of the wafer 102 and the rigid pad 3.

[0059] The baffle plate 4 is configured to cover the limiting block 2 and the flange 106 of the wafer 102 and limit the rigid pad 3 in the radial direction of the wafer 102, and the baffle plate 4 is detachably connected to the tray 1 so as to limit the position in the vertical direction.

[0060] Preferably, the tray 1, the stop block 2, the rigid pad 3 and the baffle 4 are all substantially cylindrical, and the central axes of the tray 1, the stop block 2, the rigid pad 3 and the baffle 4 are in the same straight line as the central axis of the wafer 102. Preferably, the tray 1 is made of metal and has good thermal conductivity. The tray 1 limits the stop block 2 in the radial direction of the wafer 102. Preferably, as Figure 8 As shown, the tray 1 has a protrusion 12 on the upper surface extending upward from the edge portion.

[0061] See also Figure 4 and Figure 5 , the limit block 2 is arranged on the tray 1 and limits the wafer 102 in the radial direction of the wafer 102. The inner diameter of the limit block 2 is consistent with the outer diameter of the wafer 102, and cooperates with the tray 1 to fix the wafer 102. That is, the central part of the limit block 2 has an opening, thereby forming the inner wall of the limit block 2, and the inner wall of the limit block 2 contacts the side wall of the wafer 102. Specifically, the flange 106 of the lower surface 108 of the wafer 102 and the lower surface of the limit block 2 are both in contact with the upper surface of the tray 1, and the flange 106 of the upper surface 107 of the wafer 102 and the upper surface of the limit block 2 are at the same height. Preferably, the limit block 2 is made of metal.

[0062] Preferably, according to the embodiment, Figure 7 As shown, the stopper 2 is provided with a flow channel 22 and a hole 21 to meet the requirement of filling the sample surface with reducing atmosphere. The flow channel 22 is arranged inside the stopper 2, and the hole 21 is arranged to penetrate the stopper 2 in the radial direction of the stopper 2. Preferably, the flow channel 22 is, for example, a channel arranged along the circumference of the stopper 2, and the flow channel 22 is connected to the hole 21.

[0063] like Fig.10 As shown, the rigid pad 3 includes a base 32 and a boss 31 above the base 32. In the radial direction of the wafer 102, the size of the boss 31 is smaller than the size of the base 32. The base 32 and the boss 31 of the rigid pad 3 are formed as one body. Preferably, the rigid pad 3 is made of metal. Figure 5 As shown, the rigid pad 3 is arranged above the upper surface 107 of the wafer 102, and the cathode molybdenum sheet to be bonded is located between the upper surface 107 of the wafer 102 and the rigid pad 3. Specifically, the base 32 is arranged above the cathode molybdenum sheet, the upper surface of the base 32 is at the same height as the flange 106 of the upper surface 107 of the wafer 102, and the upper surface of the boss 31 is slightly lower than the upper surface of the body 41. Preferably, the boss 31 is slightly lower than the baffle 40.5-1.5mm, so as to provide deformation filling space for the elastomer 105, thereby reducing the deformation of the elastomer 105 and improving its service life.

[0064] like Figure 5As shown, the baffle 4 is configured to cover the stop block 2 and the flange 106 of the wafer 102 and to limit the rigid pad 3 in the radial direction of the wafer 102, and the baffle 4 is detachably connected to the tray 1 so as to limit the position in the vertical direction. Fig. 9 As shown, the baffle 4 includes a main body 41, a vertical wall 42 and a lower flange 43. The central part of the main body 41 has an opening to form the inner wall of the main body 41, and the inner wall of the main body 41 contacts the side wall of the boss 31 of the rigid pad 3. The lower surface of the lower flange 43 contacts the tray 1, and the main body 41 is connected to the lower flange 43 as a whole through the vertical wall 42. The inner side of the vertical wall 42 facing the wafer 102 contacts the outer wall of the limit block 2, and the lower flange 43 is detachably connected to the tray 1 so as to limit the position vertically. Since the size of the boss 31 is smaller than the size of the base 32 in the radial direction of the wafer 102, in this case, the lower surface of the main body 41 simultaneously covers and contacts the upper surface of the boss 31 of the rigid pad 3, the flange 106 of the upper surface 107 of the wafer 102 and the upper surface of the limit block 2. Preferably, the baffle 4 is made of metal, and the thickness of the baffle 4 is ≥2mm. Through the above arrangement, the baffle 4 shields the red glue at the terminal of the wafer 102 to prevent pressure damage.

[0065] According to the embodiments of the present application, Figure 5 As shown, the upper surface of the protrusion 12 of the tray 1 contacts the lower surface of the lower flange 43 of the baffle 4, and the wall portion of the protrusion 12 facing the wafer 102 contacts the outer wall of the stop block 2. In this case, in the radial direction of the wafer 102, the outer wall of the stop block 2 contacts the vertical wall 42 of the baffle 4 and the protrusion 12 of the tray 1 at the same time.

[0066] Furthermore, if Figure 4 and Figure 5 As shown, the bonding fixture 100 for bonding the wafer 102 according to the present invention also includes an elastic membrane 5 and a pressure ring 6. Preferably, the axes of the pressure ring 6 and the elastic membrane 5 are on the same straight line as the axis of the wafer 102. The shape and size of the elastic membrane 5 are set to correspond to the baffle 4, so that the elastic membrane 5 covers the upper surface of the boss 31 of the rigid pad 3 and the upper surface of the baffle 4 at the same time, thereby protecting the elastomer 105 of the pressure head 103 from damage. Preferably, the material of the elastic membrane 5 is Teflon, and the thickness of the elastic membrane 5 is ≥1mm. Further, a through hole is provided on the elastic membrane 5 to allow the reducing gas to enter. The pressure ring 6 is annular and is arranged above the lower flange 43 of the baffle 4 so as to be detachably connected to the lower flange 43 and the protrusion 12 of the tray 1, thereby fixing the elastic membrane 5 at the edge.

[0067] Preferably, if Figures 4 to 12As shown, the edge portions of the six components, namely, the elastic membrane 5, the pressure ring 6, the rigid pad 3, the baffle 4, the limit block 2 and the tray 1, are correspondingly provided with mounting holes or grooves to connect the elastic membrane 5, the pressure ring 6, the rigid pad 3, the baffle 4, the limit block 2 and the tray 1 to each other, and to fix the elastic membrane 5, the pressure ring 6, the rigid pad 3, the baffle 4, the limit block 2 to the tray 1.

[0068] like Figure 1 As shown, according to the present invention, the bonding device 101 includes the above-mentioned bonding fixture 100. According to an embodiment of the present invention, the method of bonding the wafer 102 using the bonding device 101 is as follows, see Figure 4 and Figure 5 .

[0069] Step 1: preheat the upper pressing head 103, especially the elastic body 105. Preferably, the preheating temperature is 180°C to ensure that the elastic body 105 is in a soft elastic state.

[0070] Step 2: Set the limit block 2 on the tray 1.

[0071] Step 3, installing the anode molybdenum sheet 109 and the wafer 102 to be bonded, so that the limiting block 2 is limited in the radial direction of the wafer 102.

[0072] Step 4: Install the cathode molybdenum sheet to be bonded on top of the wafer 102 .

[0073] Step 5, installing the rigid spacer 3 above the cathode molybdenum sheet.

[0074] Step 6: Install the baffle 4 to limit the rigid pad 3 in the radial direction of the wafer 102 .

[0075] Step 7: Install the elastic membrane 5.

[0076] Step 8, installing the pressure ring 6, detachably connecting the pressure ring 6 and the baffle 4 to the tray 1, and fixing the elastic membrane 5 to limit the position in the vertical direction.

[0077] Step 9: Install the bonding fixture 100 in the bonding device 101 and between the pressing heads 103 .

[0078] Step 10, performing bonding operation, introducing reducing atmosphere into the bonding fixture 100 during the preheating and bonding process, so as to protect the bonding sample from oxidation and improve the bonding quality.

[0079] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bonding fixture (100) for bonding a wafer (102), wherein the upper surface (107) and the lower surface (108) of the wafer (102) respectively have symmetrical flanges (106) extending upward and downward at the edge portions, characterized in that: The bonding fixture (100) comprises a tray (1), a limit block (2), a rigid pad (3), and a baffle (4); the wafer (102) is arranged on the tray (1), and the anode molybdenum sheet (109) to be bonded is located between the tray (1) and the wafer (102); The limiting block (2) is arranged on the tray (1) and limits the position of the wafer (102) in the radial direction of the wafer (102); the tray (1) limits the position of the limiting block (2) in the radial direction of the wafer (102); The rigid pad (3) is arranged above the upper surface (107) of the wafer (102), and the cathode molybdenum sheet to be bonded is located between the upper surface (107) of the wafer (102) and the rigid pad (3). The baffle plate (4) is arranged to cover the limit block (2) and the flange (106) of the wafer (102) and to limit the rigid pad (3) in the radial direction of the wafer (102), and the baffle plate (4) is detachably connected to the tray (1) so as to limit the position in the vertical direction; The flange (106) of the lower surface (108) of the wafer (102) and the lower surface of the stop block (2) are both in contact with the upper surface of the tray (1), and the flange (106) of the upper surface (107) of the wafer (102) and the upper surface of the stop block (2) are at the same height; The central portion of the limiting block (2) has an opening, thereby forming an inner wall of the limiting block (2), and the inner wall of the limiting block (2) contacts the side wall of the wafer (102).

2. The bonding fixture (100) according to claim 1, characterized in that: The tray (1), the limit block (2), the rigid pad (3) and the baffle (4) are all cylindrical, and the central axis of the tray (1), the limit block (2), the rigid pad (3) and the baffle (4) is on the same straight line as the central axis of the wafer (102).

3. The bonding fixture (100) according to claim 2, characterized in that: The rigid pad (3) comprises a base (32) and a boss (31) above the base (32), wherein the size of the boss (31) is smaller than the size of the base (32) in the radial direction of the wafer (102); The base (32) is arranged above the cathode molybdenum sheet, the upper surface of the base (32) is at the same height as the flange (106) of the upper surface (107) of the wafer (102), and the upper surface of the boss (31) is slightly lower than the upper surface of the main body (41).

4. The bonding fixture (100) according to claim 3, characterized in that: The baffle (4) comprises a main body (41), a vertical wall (42) and a lower flange (43); the central portion of the main body (41) has an opening to form an inner wall of the main body (41); the inner wall of the main body (41) contacts the side wall of the boss (31) of the rigid pad (3); The lower surface of the lower flange (43) contacts the tray (1), the main body (41) is connected to the lower flange (43) as a whole via the vertical wall (42), the inner side of the vertical wall (42) facing the wafer (102) contacts the outer wall of the limit block (2), and the lower flange (43) is detachably connected to the tray (1).

5. The bonding fixture (100) according to claim 4, characterized in that: The tray (1) has a protrusion (12) on its upper surface extending upward from an edge portion, the upper surface of the protrusion (12) contacts the lower surface of a lower flange (43) of the baffle (4), and the wall portion of the protrusion (12) facing the wafer (102) contacts the outer wall of the limit block (2).

6. The bonding fixture (100) according to claim 5, characterized in that: The bonding fixture (100) further comprises an elastic membrane (5) and a pressure ring (6); The shape and size of the elastic membrane (5) are set to correspond to the baffle (4), so that the elastic membrane (5) covers the upper surface of the boss (31) of the rigid pad (3) and the upper surface of the baffle (4) at the same time; The pressure ring (6) is annular and is disposed above the lower flange (43) of the baffle (4) so ​​as to be detachably connected to the lower flange (43) and the protrusion (12) of the tray (1), thereby fixing the elastic membrane (5) at the edge; The central axis of the pressure ring (6), the central axis of the elastic membrane (5) and the central axis of the wafer (102) are on the same straight line.

7. The bonding fixture (100) according to claim 6, characterized in that: The elastic membrane (5) is provided with a through hole.

8. The bonding fixture (100) according to claim 1, characterized in that: The limiting block (2) is provided with a flow channel (22) and a hole (21); the flow channel (22) is arranged inside the limiting block (2); the hole (21) is arranged to penetrate the limiting block (2) in the radial direction of the limiting block (2); and the flow channel (22) is communicated with the hole (21).

9. A bonding device (101) for bonding a wafer (102), characterized in that: The bonding fixture (100) comprises the bonding fixture (100) and the pressing head (103) according to any one of claims 1 to 8, wherein the pressing head (103) comprises two upper and lower pressing heads (103), and the bonding fixture (100) is arranged between the pressing heads (103).

10. The bonding device (101) according to claim 9, characterized in that The pressure head (103) at the upper end comprises a rigid frame (104) and an elastic body (105).

11. The bonding device (101) according to claim 10, characterized in that The rigid frame (104) is in the shape of a groove, and the elastic body (105) is arranged in the groove.

12. The bonding device (101) according to claim 10, characterized in that The elastic body (105) is installed in the rigid frame (104) and extends out of the rigid frame (104).

13. A method for bonding a wafer (102), characterized in that: The method uses the bonding device (101) according to any one of claims 9 to 11, and the method comprises: Step 1, preheating the upper pressure head (103); Step 2, setting the limit block (2) on the tray (1); Step 3, installing the anode molybdenum sheet (109) to be bonded with the wafer (102), so that the limiting block (2) is limited in the radial direction of the wafer (102); Step 4, installing the cathode molybdenum sheet to be bonded on top of the wafer (102); Step 5, installing the rigid spacer (3) above the cathode molybdenum sheet; Step 6, installing a baffle (4) to limit the rigid pad (3) in the radial direction of the wafer (102); Step 7, installing the elastic membrane (5); Step 8, installing the pressure ring (6), detachably connecting the pressure ring (6) and the baffle (4) to the tray (1), and fixing the elastic membrane (5) to limit the position in the vertical direction; Step 9, installing the bonding fixture (100) in the bonding device (101) between the pressure heads (103); Step 10, introducing a reducing atmosphere into the bonding fixture (100) during the preheating and bonding process to perform a bonding operation.

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