A multi-purpose multi-layer low-temperature gold-gold bonding tooling and method

Abstract

The present invention discloses a multi-purpose multi-layer low-temperature gold-gold bonding tooling. A substrate positioning groove is provided in the positioning groove block, and each substrate to be bonded is fixed by a positioning pin. The pressure block two with a larger area transmits the pressure to the substrate to be bonded. This tooling has a pressure amplification function. The present invention also discloses a multi-purpose multi-layer low-temperature gold-gold bonding method. First, high-precision through holes and positioning holes are formed on the substrate to be bonded, and a metal film layer for bonding with good uniformity is prepared on the surface. The substrates to be bonded are sequentially fixed in the tooling according to the bonding sequence, and temperature and pressure are applied through an isostatic pressing device to complete the bonding. The present invention significantly reduces the bonding temperature, provides a reliable and convenient way for the tight bonding between substrates of various materials, and the number of substrate bonding layers is not limited. In particular, it provides an effective method for the bonding of substrates with buried chips, meeting the usage requirements of buried chips for the ambient temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and mainly relates to a multi-purpose multi-layer low-temperature gold-gold bonding tooling and method. Background Art

[0002] Gold-gold bonding is a type of metal bonding. By applying temperature and pressure, the metal lattice is deformed to form defects and then fuse together.

[0003] The commonly used bonding method in the industry is to use special equipment. After aligning the upper and lower two-layer substrates through surface patterns, bonding is completed under the action of a high temperature of about 300 °C and a pressure of about 10 MPa to 30 MPa. This bonding method usually requires the substrate to be a standard wafer and also has very high requirements for the surface roughness of the bonding substrate, usually in the order of nm. Moreover, only two-layer substrate bonding can be achieved at a time. If multi-layer bonding is to be realized, multiple alignments and multiple bondings are required, and the alignment error will accumulate continuously. At the same time, the bonding temperature is higher than the conductive adhesive bonding / gold-tin soldering temperature, and the reliability of the assembled chip cannot be guaranteed. Therefore, it is difficult to achieve the bonding between substrates with buried chips. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects, and provide a multi-purpose multi-layer low-temperature gold-gold bonding tooling and method, which solves the technical problems of high bonding temperature, large multi-layer bonding error, and difficulty in achieving bonding between substrates with buried chips during the existing gold-gold bonding. It can significantly reduce the bonding temperature, provide a reliable and convenient way for the tight bonding between substrates of various materials such as silicon, glass, and quartz, and the number of substrate bonding layers is not limited. In particular, it provides an effective method for the bonding of substrates with buried chips inside, meeting the usage requirements of the buried chips for the ambient temperature.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] A multi-purpose multi-layer low-temperature gold-gold bonding tooling includes a base, a stopper, a positioning groove block, a first pressing block, a second pressing block, and a positioning pin;

[0007] The stopper is installed on the base;

[0008] The stopper is provided with a positioning groove block mounting hole that matches the outer surface shape of the positioning groove block, and the positioning groove block is installed in the positioning groove block mounting hole;

[0009] The positioning groove block is provided with a substrate positioning groove for defining the placement position of the substrate to be bonded. The outer surface shape of the first pressing block matches the shape of the substrate positioning groove, and the first pressing block is placed in the substrate positioning groove and presses on the substrate to be bonded;

[0010] The outer surface shape of the second pressing block matches the shape of the mounting hole of the positioning groove block. The second pressing block is placed in the mounting hole of the positioning groove block and presses on the first pressing block. The pressure of the warm water static isostatic pressing equipment acts on the upper surface of the second pressing block;

[0011] The substrate to be bonded is provided with positioning holes;

[0012] When the number of substrates to be bonded > 1, the positioning pins are inserted into the positioning holes of each substrate to be bonded for fixation;

[0013] The substrate to be bonded can be cavity - opened and embedded with chips, that is, the substrate to be bonded can contain chips or not.

[0014] Furthermore, in the above - mentioned multi - purpose multi - layer low - temperature Au - Au bonding tooling, the outer surface shapes of the base, the limiter, the positioning groove block, and the second pressing block are disc - shaped, and the outer surface shape of the first pressing block is square;

[0015] The mounting hole of the positioning groove block provided on the limiter is a circular through - hole, and the substrate positioning groove provided on the positioning groove block is a square groove;

[0016] The depth of the substrate positioning groove is equal to the height of the positioning groove block.

[0017] Furthermore, in the above - mentioned multi - purpose multi - layer low - temperature Au - Au bonding tooling, the upper surface of the base is provided with a circular limiting boss. The limiting boss cooperates with the mounting hole of the positioning groove block of the limiter, and a first rubber sealing ring is provided at the mating part (i.e., the joint) of the limiting boss and the mounting hole of the positioning groove block;

[0018] A second rubber sealing ring is provided at the mating part (i.e., the joint) of the second pressing block and the mounting hole of the positioning groove block.

[0019] Furthermore, in the above - mentioned multi - purpose multi - layer low - temperature Au - Au bonding tooling, the substrate to be bonded is one of a silicon substrate, a glass substrate, or a quartz substrate;

[0020] A metal film layer with a surface roughness better than 0.2μm is prepared on the surface of the substrate to be bonded; the total thickness of the metal film layer is 2μm - 3μm, including a sputtering film layer and an electroplating film layer. Among them, the sputtering film layer is one of TiW / Au, NiCr / Au, TiW / Ni / Au, NiCr / Ni / Au, Cu / Ni / Au, or TaN / NiCr / Ni / Au, and the total thickness of the sputtering film layer The electroplating film layer is Au;

[0021] The positioning holes provided on the substrate to be bonded are etched by ICP process. The etching accuracy of the positioning holes is better than ±2μm, and the aperture size accuracy is better than ±5μm.

[0022] Furthermore, in the above - mentioned multi - purpose multi - layer low - temperature Au - Au bonding tooling, the positioning holes provided on the substrate to be bonded are located at non - graphic positions on the substrate to be bonded;

[0023] The number of the positioning holes ≥ 3, and the positioning holes are asymmetrically distributed for identifying the direction of the substrate to be bonded.

[0024] Further, in the above-mentioned multi-purpose multi-layer low-temperature gold-gold bonding tooling, the pressure P of the static isostatic pressing device acts on the upper surface of the second pressing block, and the upper surface of the first pressing block pressed on the substrate to be bonded is higher than the upper surface of the area outside the substrate positioning groove in the positioning groove block;

[0025] The upper surface area of the second pressing block > the upper surface area of the first pressing block > the area of the substrate to be bonded;

[0026] The pressure P of the warm water static isostatic pressing device = P1 / (S1 / S2), where P1 is the required pressure for pressing the substrate to be bonded, S1 is the upper surface area of the second pressing block, and S2 is the area of the substrate to be bonded;

[0027] When the pressing temperature of the warm water isostatic pressing device is 85°C, P1 = 150 MPa - 200 MPa.

[0028] Further, in the above-mentioned multi-purpose multi-layer low-temperature gold-gold bonding tooling, the material used for the multi-purpose multi-layer low-temperature gold-gold bonding tooling is 30CrMnSi;

[0029] The size of the substrate to be bonded ≤ 8 inches;

[0030] When the number of substrates to be bonded > 1, the total thickness of each substrate to be bonded ≤ 3 mm.

[0031] A multi-purpose multi-layer low-temperature gold-gold bonding method is realized by using the above-mentioned multi-purpose multi-layer low-temperature gold-gold bonding tooling, and includes:

[0032] Processing positioning holes on the substrate to be bonded;

[0033] Installing the stopper on the base, and installing the positioning groove block in the positioning groove block installation hole provided by the stopper;

[0034] Putting > 1 substrates to be bonded into the substrate positioning groove provided by the positioning groove block in a stacked order, and aligning the positioning holes of each substrate to be bonded;

[0035] Inserting positioning pins into the positioning holes of each substrate to be bonded for fixation;

[0036] Making each fixed substrate to be bonded located at the center of the substrate positioning groove;

[0037] Putting the first pressing block into the substrate positioning groove;

[0038] Putting the second pressing block into the positioning groove block installation hole;

[0039] After packaging the multi-purpose multi-layer low-temperature gold-gold bonding tooling, placing it in a warm water isostatic pressing device for pressing.

[0040] Further, in the above multi-purpose multi-layer low-temperature gold-gold bonding method, positioning holes are machined on the substrate to be bonded by ICP process.

[0041] Further, in the above multi-purpose multi-layer low-temperature gold-gold bonding method, it also includes that while positioning holes are machined on the substrate to be bonded by ICP process, through holes for signal transmission and chip embedding cavities are etched by ICP process; after the etching of the through holes and chip embedding cavities is completed, circuit patterns are prepared on the surface of the substrate to be bonded by sputtering, photolithography and electroplating processes, the chips are assembled into the chip embedding cavities, and the surface of the bonding substrate is cleaned by Ar plasma.

[0042] Further, in the above multi-purpose multi-layer low-temperature gold-gold bonding method, the substrate positioning groove provided on the positioning groove block is a square groove;

[0043] Put >1 substrates to be bonded into the substrate positioning groove provided on the positioning groove block in a stacking order, push the stacked substrates to any corner of the substrate positioning groove so that the positioning holes of the substrates to be bonded are aligned;

[0044] The method for packaging the multi-purpose multi-layer low-temperature gold-gold bonding tooling is to cover the tooling with silica gel and put it into a sealed bag for vacuum pumping;

[0045] The conditions for placing the multi-purpose multi-layer low-temperature gold-gold bonding tooling in an isostatic pressing equipment for pressing are: preheating temperature 80 - 90°C, preheating time 1 - 3h, pressing temperature 80 - 90°C, pressing time 10 - 15h, and the pressure applied on the substrate to be bonded is 150MPa - 200MPa.

[0046] The present invention has the following beneficial effects compared with the prior art:

[0047] (1) The present invention creatively designs a bonding tooling, which significantly amplifies the pressure of the equipment by using the bonding tooling, and the pressure at the bonding part of the product can reach 150MPa - 200MPa, creating a basis for the firm bonding between silicon wafers;

[0048] (2) In the bonding tooling of the present invention, the method of using movable positioning pins to cooperate with the positioning holes on the substrate realizes the simultaneous and precise positioning between multiple substrates. Specifically, the bonding of any number of substrates with a thickness of 0.3mm - 3mm can be completed at one time, and the positioning holes can be set at any position on the substrate, making the operation more convenient. Compared with the traditional method of aligning patterns between two substrates, the present invention effectively improves the positioning accuracy and efficiency;

[0049] (3) The bonding tooling of the present invention is made of high-strength structural steel. The processed tooling has extremely high flatness and surface finish, and can withstand a pressure of 200MPa without deformation;

[0050] (4) The bonding temperature of the present invention is 80 - 90 °C, which is about 200 °C lower than the conventional bonding temperature. It is applicable to the bonding of substrates for chip - active microwave modules, meets the requirements of the assembly reliability of active chips in packaging, and provides an effective method for the bonding of substrates with buried chips inside.

[0051] (5) The present invention can be compatible with the bonding of substrates of any size below 8 inches. Therefore, it can be used not only for the bonding of standard - sized substrates but also for the bonding of non - standard - sized substrates.

[0052] (6) The present invention uses a warm - water isostatic press in cooperation with tooling, and the pressure application is more uniform and stable. Description of the Drawings

[0053] Figure 1 It is a flowchart of a preferred multi - purpose multi - layer low - temperature gold - gold bonding method of the present invention;

[0054] Figure 2 It is a structural diagram of a preferred multi - purpose multi - layer low - temperature gold - gold bonding tooling of the present invention;

[0055] Figure 3 It is a schematic diagram of the base structure in the embodiment of the present invention; among them, Figure (a) is a three - dimensional view, (b) is a top view, (c) is a front view, and (d) is a dimension view;

[0056] Figure 4 It is a schematic diagram of the limiter structure in the embodiment of the present invention; among them, Figure (a) is a three - dimensional view, (b) is a top view, (c) is a front view, and (d) is a dimension view;

[0057] Figure 5 It is a schematic diagram of the positioning groove block structure in the embodiment of the present invention; among them, Figure (a) is a three - dimensional view, (b) is a top view, (c) is a front view, and (d) is a dimension view;

[0058] Figure 6 It is a schematic diagram of the first pressing block structure in the embodiment of the present invention; among them, Figure (a) is a three - dimensional view, (b) is a top view, (c) is a front view, and (d) is a dimension view;

[0059] Figure 7 It is a schematic diagram of the second pressing block structure in the embodiment of the present invention; among them, Figure (a) is a three - dimensional view, (b) is a top view, (c) is a front view, and (d) is a dimension view;

[0060] Figure 8 It is the processing layout of the substrate to be bonded in the embodiment of the present invention; among them, (a) - (d) are the processing layouts of the substrates to be bonded from bottom to top respectively;

[0061] Figure 9 It is a physical diagram of the substrate after bonding in the embodiment of the present invention;

[0062] In the figure, 1 - base, 2 - limiter, 3 - positioning groove block, 4 - substrate to be bonded, 5 - first pressing block, 6 - second pressing block, 7 - positioning pin, 8 - chip. Detailed implementation manners

[0063] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite along with these descriptions.

[0064] The special term "exemplary" here means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0065] The present invention provides a multi - purpose multi - layer low - temperature gold - gold bonding tooling. A substrate positioning groove is provided in the positioning groove block, and each substrate to be bonded is fixed by a positioning pin. The second pressing block with a larger area transmits the pressure to the substrate to be bonded. This tooling has a pressure amplification function. The present invention also provides a multi - purpose multi - layer low - temperature gold - gold bonding method. First, high - precision through - holes, positioning holes and chip embedding cavities for signal transmission are formed on the substrate to be bonded, and a metal film layer for bonding with good uniformity is prepared on the surface. After the chip is assembled onto the substrate, the substrates to be bonded are sequentially fixed in the tooling according to the bonding sequence, and temperature and pressure are applied through an isostatic pressing device to complete the bonding. The present invention significantly reduces the bonding temperature, provides a reliable and convenient way for the tight bonding between substrates of various materials such as silicon, glass, and quartz, and the number of substrate bonding layers is not limited. In particular, it provides an effective method for the bonding of substrates with embedded chips, meeting the usage requirements of the embedded chips for the ambient temperature. The multi - purpose multi - layer low - temperature gold - gold bonding method of the present invention uses a warm - water isostatic pressing device, adopts mechanical alignment with positioning pins, and combines a special tooling to amplify the pressure and thus reduce the bonding temperature. Using this method, multi - layer substrate bonding can be completed at one time at a temperature of 85°C. The present invention is not only applicable to the gold - gold bonding of silicon substrates, but also can be applied to the gold - gold bonding of other substrates such as glass. It can be compatible with the bonding of any number of layers with a total thickness of less than 3 mm and any size of substrates with a size of less than 8 inches, and can play a role in amplifying the pressure. The effective bonding pressure applied on the substrate to be bonded can reach more than 150 MPa. The following will be combined with Figures 1-9 to describe the technical solution of the present invention in detail.

[0066] As Figure 2The figure shows a preferred structure of the multi - purpose multi - layer low - temperature Au - Au bonding tooling of the present invention, which includes: a base 1, on which there is a limit boss for clamping a stopper 2. The stopper 2 is circular - ring - shaped and is used to define the placement position of a positioning groove block 3. The positioning groove block 3 is provided with a square groove for defining the placement position of a substrate to be bonded 4. A positioning pin 7 is used for the alignment of the substrate to be bonded 4, and a first pressing block 5 is used for the vertical fixation of the substrate to be bonded 4. A second pressing block 6 is superimposed thereon. After the pressure of the second pressing block 6 is transmitted to the product to be bonded 4 through the first pressing block 5, the pressure will be amplified.

[0067] Further, the material of the tooling is 30CrMnSi, which can withstand a high pressure of 200 MPa without deformation, and the surface roughness of the tooling is better than 0.8 μm.

[0068] Further, the size of the first pressing block 5 of the tooling is smaller than that of the second pressing block 6. The equipment pressure is applied to the second pressing block 6. The area of the second pressing block 6 is larger than the area of the substrate to be bonded 4. After the pressure of the second pressing block 6 is transmitted to the substrate to be bonded through the first pressing block 5, the pressure will be amplified and applied to the substrate to be bonded 4. Under the condition of the same acting force, the pressure is inversely proportional to the force - receiving area. Therefore, the pressure received by the substrate to be bonded 4 is amplified. The amplification multiple of the pressure applied to the substrate to be bonded 4 = the area of the second pressing block 6 / the area of the substrate to be bonded. That is, the actual pressure applied to the substrate to be bonded 4 = (the area of the second pressing block 6 / the area of the substrate to be bonded 4) * the equipment pressing pressure.

[0069] Further, the outer diameter of the positioning groove block 3 is equal to the inner diameter of the stopper 2 (i.e., the diameter of the mounting hole of the positioning groove block). The side length of the substrate positioning groove is 5 - 10 mm larger than the side length of the substrate to be bonded 4. The size of the first pressing block 5 is approximately equal to that of the substrate positioning groove. The height of the first pressing block 5 is equal to the height of the positioning groove block 3. The diameter of the second pressing block 6 is equal to the inner diameter of the stopper 2; the diameter of the limit boss provided on the base 1 is equal to the inner diameter of the stopper 2;

[0070] Further, the height of the positioning pin varies from 0.3 mm to 3 mm and can be compatible with the bonding of any number of substrate layers with a total thickness between 0.3 mm and 3 mm.

[0071] As Figure 1 shown, a preferred method of the multi - purpose multi - layer Au - Au bonding method of the present invention includes the following steps:

[0072] Step 1: On the substrate 4 to be bonded, through the ICP (Inductively Coupled Plasma) process, vias for signal transmission, positioning holes, and chip embedding cavities are etched. Through the implementation of high-precision micro-etching technology, the positioning accuracy of the positioning hole etching is better than ±2μm, and the aperture size accuracy is better than ±5μm, which is better than the conventional method for manufacturing positioning holes. The positioning holes are asymmetrically arranged at any position outside the product distribution area and can be used to identify the direction of the substrate. The method of the present invention does not only allow a single material, and the restriction on the material of the substrate to be bonded is small. The substrate 4 to be bonded can be a silicon substrate, or a glass or quartz substrate. The maximum size of the substrate is 8 inches, which can accommodate more circuit layout applications; cavities can be opened inside the substrate to be bonded, and it is not required to be a continuous plane, which is suitable for the packaging application of embedding chips.

[0073] Step 2: A metal film layer is prepared on the surface of the substrate 4 to be bonded through the sputtering photolithography electroplating process. The sputtered film layer can be TiW / Au, NiCr / Au, TiW / Ni / Au, NiCr / Ni / Au, Cu / Ni / Au, TaN / NiCr / Ni / Au, etc., and the total thickness The electroplated film layer is an Au film layer, and the total thickness of the film layer after electroplating is 2μm - 3μm. The surface roughness of the film layer is better than 0.2μm, and a smoother surface is not required. After electroplating is completed, the product circuit pattern is etched on the substrate through the photolithography process.

[0074] Step 3: If chips need to be embedded, the chips 8 can be assembled onto the substrate 4 to be bonded through the bonding or welding process.

[0075] Step 4: The surface of the silicon substrate 4 to be bonded is cleaned by Ar plasma. After cleaning, it is inspected under a 40-fold microscope. The surface of the substrate after cleaning is smooth, without discoloration, and there are no movable particles. In this step, the plasma type preferably selects the radio frequency plasma with suitable cleaning intensity and damage degree for the thin-film metal surface, and through process development, the optimal cleaning parameters are determined to ensure that the surface to be bonded remains clean, without foreign contamination, and the composite film layer on the bonding surface has no obvious damage.

[0076] Step 5: After the gold bonding tooling base 1, the limiter 2, and the positioning groove block 3 are clamped together, pick up the substrate 4 to be bonded with an anti-static tweezer and place it into the groove of the positioning groove block 3 in the stacking direction and sequence in turn.

[0077] Push the stacked substrates 4 to be bonded to any corner of the groove with an anti-static tweezer, and align the alignment holes on the substrate 4 to be bonded to achieve rough alignment.

[0078] Select the positioning pin 7, and pick up the positioning pin 7 vertically with an anti-static tweezer and insert it into the aligned alignment holes. The height of the positioning pin should be lower than the upper surface height of the topmost substrate 4 to be bonded, but higher than the lower surface height of the topmost substrate 4 to be bonded.

[0079] Gently press the surface of the substrate 4 to be bonded with the tip of an anti-static tweezer. After ensuring that the substrate 4 to be bonded is flat, then push the substrate 4 to be bonded to the center of the slot.

[0080] Hold the first pressing block 5 by hand and gently place it into the slot of the positioning slot block 3.

[0081] Hold the second pressing block 6 by hand and gently place it into the stopper 2.

[0082] Put rubber sealing rings on the connection between the base 1 and the stopper 2, and on the connection between the stopper 2 and the second positioning block 6.

[0083] Cover the upper part of the base 1 with silica gel and place it in a sealed bag for vacuuming to complete the packaging.

[0084] Step 6: Place the packaged substrate 4 to be bonded into a warm water isostatic pressing device, set the pressing conditions for Au-Au bonding. The pressing conditions are: preheating temperature 85°C, preheating time 2 h, pressing temperature 85°C, pressing time 12 h, and the pressure set by the device = the required pressure for substrate pressing / (the area of the second pressing block 6 / the area of the substrate 4 to be bonded).

[0085] Furthermore, at 85°C, to achieve reliable Au-Au bonding between substrates, the effective bonding pressure applied on the substrate to be bonded is 150 MPa - 200 MPa.

[0086] Furthermore, for the warm water isostatic pressing device, pressure is applied through warm water as a medium, with a temperature uniformity better than ±1°C, a pressure accuracy better than ±2.5%, and uniform pressure application.

[0087] Furthermore, the pressure directly applied to the substrate 4 to be bonded is 150 MPa - 200 MPa, which is much greater than the conventional bonding pressure, and a more reliable bonded body can be obtained. The bonding temperature is preferably 85°C, which is much lower than 300°C of the conventional bonding.

[0088] Examples:

[0089] Step 1: On the substrate to be bonded, etch vias, positioning holes, and chip embedding cavities through ICP process. The substrate to be bonded is a 4-layer silicon substrate, with a single-layer thickness of 0.2 mm, a surface roughness of 0.08 μm, and an outer dimension of 29 mm * 29 mm. There are 3 positioning holes on each layer of the substrate, and the designed aperture value is Φ1.51 mm, which are respectively set at the upper side, left side, and right non-graphic positions of each layer of the substrate. It can be used not only for positioning but also for identifying the direction of the substrate. The ICP etching rate is 3 μm / min. After etching, image measurement is used, and the etching accuracy of the positioning holes is better than ±2 μm, and the aperture size accuracy is better than ±5 μm.

[0090] Step 2: Prepare a metal film layer on the surface through a sputtering photolithography electroplating process. The sputtered film layer is TaN / NiCr / Ni / Au, with a total thickness of approximately The electroplated film layer is an Au film layer. After electroplating, the total thickness of the film layer is 2 μm to 3 μm, and the surface roughness of the film layer is 0.05 μm.

[0091] Step 3: Assemble the chip to be buried into the chip burial cavity through a conductive adhesive bonding process.

[0092] Step 4: Perform surface Ar plasma cleaning on the silicon substrate to be bonded for 2 minutes. After cleaning, check under a 40 - fold microscope. The surface of the cleaned substrate is smooth, without color change and without movable particulate matter.

[0093] Step 5: After clamping the gold - gold bonding tooling base 1, the limiter 2, and the positioning groove block 3 together, pick up the substrate to be bonded 4 with an anti - static tweezer and place it into the groove of the positioning groove block 3 in the stacking direction and sequence.

[0094] Use an anti - static tweezer to push the stacked substrates to any corner of the groove and align the alignment holes on the substrates to achieve rough alignment.

[0095] Select the positioning pin 7, pick it up vertically with an anti - static tweezer, and insert it into the aligned alignment holes. The diameter of the selected positioning pin is 1.5 mm and the height is 0.7 mm.

[0096] Gently press the surface of the substrate with the tip of the anti - static tweezer. After ensuring that the substrate to be bonded is flat, then push the substrate to be bonded to the center of the groove.

[0097] Hold the first pressing block 5 by hand and gently place it into the groove of the positioning groove block 3.

[0098] Hold the second pressing block 6 by hand and gently place it into the limiter 2.

[0099] Put rubber sealing rings at the connection between the base 1 and the limiter 2, and at the joint between the limiter 2 and the second positioning block 6 to prevent the pressing pressure from affecting the joint seam.

[0100] Cover the upper part of the base 1 with silicone and put it into a sealed bag for vacuuming to complete the packaging.

[0101] Step 6: Put the packaged substrate to be bonded into a warm - water isostatic pressing device, set the pressing conditions for gold - gold bonding. The pressing conditions are: preheating temperature 85°C, preheating time 2 h, pressing temperature 85°C, pressing time 12 h, and the pressure set by the device = 150 MPa / (π*51*51 / (29*29)) = 15.4 MPa.

[0102] As Figure 8This is the layout for substrate processing in this embodiment. The physical diagram of the bonding effect after cutting off the non-graphic area of the substrate is as shown in Figure 9 . The bonding strength meets the requirements of GJB548B (area 4.13 mm 2 , shear strength ≥ 50 N).

[0103] As shown in Figures 3-7 , the dimensions of the bonding tooling in this embodiment are as follows: the diameter of base 1 is 124 mm, the diameter of the boss is 101 mm, the overall height of base 1 is 15 mm, and the height of the boss is 2 mm. The structural dimensions of the limiter 2 are as shown in Figure 3 , with an inner diameter of 101 mm, an outer diameter of 116 mm, and a height of 27 mm. The structural dimensions of the positioning groove block 3 are as shown in Figure 4 , with an outer diameter of 101 mm, a height of 15 mm. The substrate positioning groove is located in the middle of the groove block, and the dimensions of the substrate positioning groove are 35.1 mm × 35.1 mm, with a height of 15 mm. The size of the first pressing block 5 is 35 mm × 35 mm, and the height is 15 mm. The diameter of the second pressing block 6 is 101 mm, and the height is 15 mm. The outer dimensions of the substrate 4 to be bonded are 29 mm × 29 mm.

[0104] The present invention proposes a low-temperature Au-Au bonding method that uses tooling to amplify pressure, thereby reducing the bonding temperature and simultaneously achieving alignment between multiple layers of substrates. This method has strong compatibility, has no special requirements for the state of the metal layer on the substrate surface, has strong versatility, and is applicable to Au-Au bonding of various substrates. The present invention has little restriction on the substrate material to be bonded: it is not limited to a single material, and can be either a silicon substrate, a quartz substrate, or a glass substrate; the surface roughness Ra of the substrate is preferably better than 0.2 μm, and a smoother surface is not required; the maximum size is 8 inches, which can accommodate more circuit layout applications; cavities can be opened inside the substrate to be bonded, and it is not required to be a continuous plane, which is suitable for encapsulation applications with buried chips. The present invention can be compatible with bonding of substrates of any size below 8 inches, and can perform bonding of any number of substrates with a total thickness above 0.3 mm and below 3 mm, which has a wider applicability than traditional bonding methods. The position of the positioning holes is not fixed and can be flexibly set at any position outside the graphic area of the substrate, giving greater freedom in product design. The bonding tooling can play a role in amplifying pressure, and the effective bonding pressure can reach above 150 MPa, which can ensure more reliable bonding.

[0105] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limitations on the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent replacements, modifications, or improvements can be made to the technical solutions of the present invention and their implementation manners, and all of these fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0106] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A multi-purpose multi-layer low-temperature gold-gold bonding method, characterized in that, Realized by using a multi-purpose multi-layer low-temperature gold-gold bonding tooling; The multi-purpose multi-layer low-temperature gold-gold bonding tooling includes a base (1), a stopper (2), a positioning groove block (3), a first pressing block (5), a second pressing block (6), and a positioning pin (7); the stopper (2) is installed on the base (1); the stopper (2) is provided with a positioning groove block mounting hole that matches the outer surface shape of the positioning groove block (3), and the positioning groove block (3) is installed in the positioning groove block mounting hole; the positioning groove block (3) is provided with a substrate positioning groove for defining the placement position of the substrate to be bonded (4), and the substrate positioning groove provided in the positioning groove block (3) is a square groove; the outer surface shape of the first pressing block (5) matches the shape of the substrate positioning groove, and the first pressing block (5) is placed in the substrate positioning groove and pressed on the substrate to be bonded (4); the outer surface shape of the second pressing block (6) matches the shape of the positioning groove block mounting hole, the second pressing block (6) is placed in the positioning groove block mounting hole and pressed on the first pressing block (5), and the pressure of the warm water static isobaric equipment acts on the upper surface of the second pressing block (6); the substrate to be bonded (4) is provided with positioning holes; the positioning pin (7) is inserted into the positioning holes of each substrate to be bonded (4) for fixation; the positioning holes provided in the substrate to be bonded (4) are etched by ICP process, and the etching accuracy of the positioning holes is better than ±2μm, and the aperture size accuracy is better than ±5μm; The pressure P of the static isobaric equipment acts on the upper surface of the second pressing block (6) and presses on the upper surface of the first pressing block (5) that is pressed on the substrate to be bonded (4), and the upper surface of the first pressing block (5) is higher than the upper surface of the area outside the substrate positioning groove in the positioning groove block (3); the upper surface area of the second pressing block (6) > the upper surface area of the first pressing block (5) > the area of the substrate to be bonded (4); the pressure P of the warm water static isobaric equipment = P1 / (S1 / S2), where P1 is the required pressure for pressing the substrate to be bonded (4), S1 is the upper surface area of the second pressing block (6), and S2 is the area of the substrate to be bonded (4); The multi-purpose multi-layer low-temperature gold-gold bonding method includes: Processing positioning holes on the substrate to be bonded (4); Installing the stopper (2) on the base (1), and installing the positioning groove block (3) in the positioning groove block mounting hole provided in the stopper (2); Putting >1 substrates to be bonded (4) into the substrate positioning groove provided in the positioning groove block (3) in the stacking order, and pushing the stacked substrates to be bonded (4) to any corner of the substrate positioning groove to align the positioning holes of each substrate to be bonded (4); Inserting the positioning pin (7) into the positioning holes of each substrate to be bonded (4) for fixation; Making each fixed substrate to be bonded (4) located at the center of the substrate positioning groove; Putting the first pressing block (5) into the substrate positioning groove; Putting the second pressing block (6) into the positioning groove block mounting hole; After the multi-purpose multi-layer low-temperature Au-Au bonding tooling is packaged, it is placed in a warm water isostatic pressing equipment for pressing; the method for packaging the multi-purpose multi-layer low-temperature Au-Au bonding tooling is to cover the tooling with silica gel and put it into a sealed bag for vacuuming; the conditions for placing the multi-purpose multi-layer low-temperature Au-Au bonding tooling in the isostatic pressing equipment for pressing are: preheating temperature 80-90°C, preheating time 1-3 h, pressing temperature 80-90°C, pressing time 10-15 h, and the pressure applied to the substrate (4) to be bonded is 150 MPa - 200 MPa.

2. The method according to claim 1, wherein The outer surface shapes of the base (1), the stopper (2), the positioning groove block (3) and the second pressing block (6) are disc-shaped, and the outer surface shape of the first pressing block (5) is square; The positioning groove block mounting hole provided in the stopper (2) is a circular through hole; The depth of the substrate positioning groove is equal to the height of the positioning groove block (3).

3. The method according to claim 2, characterized in that, The upper surface of the base (1) is provided with a circular limiting boss, which is matched with the positioning groove block mounting hole of the stopper (2), and a first rubber sealing ring is provided at the matching position of the limiting boss and the positioning groove block mounting hole; A second rubber sealing ring is provided at the matching position of the second pressing block (6) and the positioning groove block mounting hole.

4. The method according to claim 1, characterized in that The substrate (4) to be bonded is one of a silicon substrate, a glass substrate or a quartz substrate; The surface of the substrate (4) to be bonded is provided with a metal film layer having a surface roughness better than 0.2 μm; the total thickness of the metal film layer is 2 μm to 3 μm, including a sputtered film layer and an electroplated film layer, wherein the sputtered film layer is one of TiW / Au, NiCr / Au, TiW / Ni / Au, NiCr / Ni / Au, Cu / Ni / Au or TaN / NiCr / Ni / Au, and the total thickness of the sputtered film layer The electroplated film layer is Au.

5. The method according to claim 1, characterized in that The positioning holes provided on the substrate (4) to be bonded are located at non-graphic positions on the substrate (4) to be bonded; The number of the positioning holes ≥ 3, and the positioning holes are asymmetrically distributed for identifying the direction of the substrate (4) to be bonded.

6. The method according to claim 1, wherein The material used for the multi-purpose multi-layer low-temperature Au-Au bonding tooling is 30CrMnSi; The size of the substrate (4) to be bonded ≤ 8 inches; When the number of substrates (4) to be bonded > 1, the total thickness of each substrate (4) to be bonded ≤ 3 mm.

7. The method according to claim 1, wherein The positioning holes are machined on the substrate (4) to be bonded by ICP process; It also includes that while the positioning holes are machined on the substrate (4) to be bonded by ICP process, through holes and chip embedding cavities for signal transmission are etched by ICP process; after the etching of the through holes and chip embedding cavities is completed, circuit patterns are prepared on the surface of the substrate (4) to be bonded by sputtering, photolithography and electroplating processes, the chips are assembled in the chip embedding cavities, and the surface of the bonded substrate (4) is subjected to Ar plasma cleaning.

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