Method of coppering a wafer bonding region

Abstract

The application relates to a method for bonding copper on a wafer bonding area, which comprises the following steps: cleaning, drying and sputtering a metal layer on the wafer; pasting a first protective film on the front surface of the copper sheet; preparing a metal adhesive paste and transferring the paste to the bonding area of the wafer; transferring the wafer with the transferred paste into a sintering jig, which is designed with an air inlet and an air outlet; accurately placing the copper sheet on the bonding area of the wafer by aligning the copper sheet and the wafer identification mark, with the bonding area of the copper sheet pasting the front surface of the paste and the copper sheet spacing between the adjacent bonding areas of the wafer being controlled within the distance causing short circuit of the wafer bonding area; sintering the wafer covered with the copper sheet; filling the epoxy resin material between the non-bonding area on the front surface of the wafer and the groove on the back surface of the copper sheet and performing plastic packaging; removing the first protective film, transferring the wafer into a wafer separator to separate the wafer into independent chip assemblies and drying. The application can improve the yield, reliability and stability of the chip.

Description

Technical Field

[0001] The invention belongs to the technical field of chip manufacturing, and specifically discloses a method for copper coating a wafer bonding area. Background Art

[0002] One known solution, such as CN106170856A, pre-coats a sintering paste onto a copper bonding sheet. This paste is then applied to the chip bonding area, where it is pressure-sintered to form a bond between the chip and the pins. This process places stringent requirements on the size of the chip bonding area. Due to limitations in the adhesive coating process, it is not suitable for smaller bonding areas (typically less than 2mm x 2mm). This can lead to copper sheet drift, resulting in short circuits and operational inconvenience. Furthermore, adhesive coating is difficult on copper sheets with height differences.

[0003] Another known solution, such as TW202345248A, uses pre-coating on a copper sheet and, similarly, pressure sintering to the die bonding area. Due to the limitations of the pre-coating process, there are also size requirements for the die bonding area, making it unsuitable for smaller bonding areas. Furthermore, due to the characteristics of the pre-coated metal film, a protective film must be applied to the exposed side of the metal film after pre-coating to prevent damage or oxidation during the transfer process. This can lead to damage to the metal film and inconvenience during the subsequent removal process. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for copper coating in the bonding area of ​​a wafer, which can improve chip yield, reliability and stability.

[0005] According to the technical solution provided by the present invention, the method for copper coating the wafer bonding area includes the following steps:

[0006] S1. Clean the wafer to be copper-clad. After cleaning, dry the wafer. After drying, sputter a metal layer on the front side of the wafer to form a bonding area and a non-bonding area on the front side of the wafer. The metal layer is made of gold or silver and has a thickness of 1-10 kÅ.

[0007] S2. Providing a copper sheet for copper cladding, wherein the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and a first protective film is applied to the front of the copper sheet;

[0008] S3, preparing a metal bonding slurry and transferring the slurry to the bonding area of ​​the wafer;

[0009] S4. The wafer after the slurry transfer is transferred to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material. The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0010] S5, sintering the wafer covered with the copper sheet;

[0011] S6, evenly filling the epoxy resin material between the non-bonding area on the front side of the wafer and the groove between the copper sheet and performing plastic sealing;

[0012] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components according to the dicing lanes of the wafer;

[0013] S8. Dry and separate the chip assembly, which includes a copper sheet, a chip, a slurry block and an epoxy resin sealant. The front of the chip is connected to the back of the slurry block, and the front of the slurry block is connected to the back of the copper sheet. The epoxy resin sealant seals the gaps between the chip and the slurry block and between the slurry block and the copper sheet.

[0014] Preferably, step S3 is specifically as follows:

[0015] S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-95%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester;

[0016] S312, transferring the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing, and controlling the coating thickness of the wet slurry to be 10 μm-100 μm;

[0017] S313. Place the wafer coated with the wet slurry in an oven for semi-curing baking. The semi-curing baking temperature is controlled at 100-180°C, the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500ppm. After the semi-curing baking is completed, the wet slurry forms a wet slurry block.

[0018] Preferably, step S3 is specifically as follows:

[0019] S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is formed by mixing metal powder and a protective agent, wherein the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises silver or copper, and the protective agent is amide or ethylenediamine;

[0020] S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller;

[0021] S323, using a mold-turning jig, remove the dry slurry corresponding to the non-bonding area of ​​the front side of the wafer from the transfer film to obtain a dry slurry block; or, using a laser etching method, cut away the dry slurry in the non-bonding area of ​​the front side of the wafer to obtain a dry slurry block;

[0022] S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170°C and a pressure of 1-15 MPa on a single dry slurry block. After the transfer is completed, peel off the transfer film.

[0023] Preferably, step S5 is specifically as follows:

[0024] S511. Cover the first protective film with a second protective film, transfer the copper-covered wafer and the sintering jig into the sintering machine together, press the second protective film with a sintering head, introduce protective gas through the air inlet on the sintering jig, perform pressure sintering, and evacuate the film during the sintering process or after the sintering is completed through the exhaust port on the sintering jig; the material of the second protective film is polytetrafluoroethylene, and the thickness of the second protective film is 10μm-200μm; during pressure sintering, the pressure of the sintering head pressing the protective film is controlled at 3-30MPa, the sintering temperature is controlled at 200-300℃, and the sintering time is controlled at 30-120s.

[0025] S512, slowly cooling the temperature after sintering is completed, and removing the second protective film after the slow cooling is completed.

[0026] Preferably, step S5 is specifically as follows:

[0027] S521. Transfer the copper-covered wafer and the sintering jig into the oven together. Introduce protective gas through the air inlet on the oven for pressure-free sintering. Vacuum the oven through the exhaust port during or after the sintering process. During pressure-free sintering, control the baking temperature at 150-300°C and the baking time at 30-90 minutes.

[0028] S522: After sintering is completed, the temperature is slowly lowered.

[0029] Preferably, step S6 is specifically as follows:

[0030] S611. Transfer the wafer with the copper sheet sintered to the compression molding mold, evenly fill the epoxy resin material in the groove between the non-bonding area on the front side of the wafer and the copper sheet, cover the first protective film with a third protective film, and attach the pressing head of the compression molding mold to the third protective film. Complete compression molding in the compression molding mold, and control the compression molding temperature at 150-250°C, the time at 10-100s, and the pressure at 10-60MPa. The material of the third protective film is PVC or PTFE, and the thickness of the third protective film is 10μm-150μm.

[0031] S612. After the compression molding is completed, the third protective film is removed, and the excess glue on the copper sheet is cleaned by mechanical grinding or laser.

[0032] Preferably, step S6 is specifically as follows:

[0033] S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the first protective film to the injection mold;

[0034] S622. After the injection mold is pressed together, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the copper sheet through a press. The injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa.

[0035] S623. After injection molding is completed, use mechanical grinding or laser to clean the excess glue on the copper sheet.

[0036] Preferably, in step S2, the thickness of the copper sheet is 100 μm-1000 μm, and the distance between the front surface of the copper sheet and the bottom of the groove is 10 μm-50 μm.

[0037] Preferably, in step S2, the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC.

[0038] Preferably, in step S7, the wafer is separated into independent chips by mechanical separation or laser separation according to the sawing lines of the wafer.

[0039] The present invention has the following advantages:

[0040] 1. The metal bonding slurry provided by the present invention (including wet slurry and dry slurry) is suitable for wafers of different bonding sizes, solving the limitations of the existing technology on bonding size requirements;

[0041] 2. The present invention provides a wafer-level copper plating process, which improves the efficiency and accuracy of copper plating;

[0042] 3. The present invention can coat copper on different wafer bonding areas through the design of copper sheets, avoiding the limitations of traditional copper coating processes that have strict requirements on bonding areas;

[0043] 4. The present invention greatly improves the chip separation yield and chip reliability through the epoxy resin filling material process;

[0044] 5. The chip protection structure formed by the process of the present invention avoids the high cost and easy cracking problems of traditional polyimide, thereby improving chip yield and reliability;

[0045] 6. The present invention provides a practical chip copper coating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a three-dimensional diagram of the chip components obtained in Example 1, Example 4, Example 5 and Example 8.

[0047] Figure 2 It is a cross-sectional view of the chip components obtained in Example 1, Example 4, Example 5 and Example 8.

[0048] Figure 3 It is a three-dimensional diagram of the chip components obtained in Example 2, Example 3, Example 6 and Example 7.

[0049] Figure 4 It is a cross-sectional view of the chip components obtained in Example 2, Example 3, Example 6 and Example 7. DETAILED DESCRIPTION

[0050] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0051] Example 1

[0052] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0053] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0054] S2. Provide a copper sheet 1 for copper cladding, wherein the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm. A first protective film is affixed to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet. The thickness of the first protective film is 25 μm-150 μm and the material of the first protective film is PVC;

[0055] S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester;

[0056] S312. Transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying, or screen printing. If the bonding area is smaller than 1 mm x 1 mm, dispensing or spraying is recommended. If the bonding area is larger than 1 mm x 1 mm, dispensing or screen printing is recommended. The coating thickness of the wet slurry is controlled within 10 μm-100 μm.

[0057] S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or excessive reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31;

[0058] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0059] S511. Cover the first protective film with a second protective film, transfer the copper-covered wafer and the sintering jig into the sintering machine together, press the second protective film with a sintering press head, the second protective film is made of polytetrafluoroethylene, and the thickness of the second protective film is 10 μm-200 μm, and introduce protective gas through the air inlet on the sintering jig to perform pressure sintering. During pressure sintering, the pressure of the sintering press head pressing the protective film is controlled at 3-30 MPa, the sintering temperature is controlled at 200-300°C, and the sintering time is controlled at 30-120 s. Vacuum is evacuated during the sintering process or after sintering is completed through the exhaust port on the sintering jig;

[0060] S512, slowly cooling after sintering is completed, and removing the second protective film after the slow cooling is completed;

[0061] S611. Transfer the wafer after the copper sheet sintering is completed to a compression mold. Cover the first protective film with a third protective film to prevent the epoxy resin material from adhering to the indenter of the compression mold. The third protective film is made of PVC or PTFE and has a thickness of 10 μm-150 μm. The indenter of the compression mold is attached to the third protective film. The epoxy resin material is evenly filled in the groove between the non-bonding area on the front side of the wafer and the copper sheet. Compression molding is completed in the compression mold. The compression molding temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is 10-60 MPa. The epoxy resin material forms epoxy resin sealant 4.

[0062] S612: After the compression molding is completed, the third protective film is removed, and the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0063] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0064] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a wet slurry block 31 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 、 Figure 2 shown.

[0065] Example 2

[0066] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0067] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0068] S2. Provide a copper sheet 1 for copper cladding, wherein the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm. A first protective film is affixed to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet. The thickness of the first protective film is 25 μm-150 μm and the material of the first protective film is PVC;

[0069] S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is formed by mixing metal powder and a protective agent, wherein the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises silver or copper, and the protective agent is amide or ethylenediamine;

[0070] S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller;

[0071] S323, using a mold-turning jig, remove the dry slurry corresponding to the non-bonding area of ​​the front side of the wafer from the transfer film to obtain a dry slurry block; alternatively, cut off the dry slurry in the non-bonding area of ​​the front side of the wafer by laser etching to obtain a dry slurry block 32;

[0072] S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa per dry slurry block. After the transfer is completed, peel off the transfer film.

[0073] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0074] S521. Transfer the copper-covered wafer and the sintering jig into an oven, introduce protective gas through the air inlet of the oven, and perform pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C. and the baking time is controlled at 30-90 minutes. Vacuum is evacuated through the exhaust port of the oven during or after the sintering process.

[0075] S522, slowly cooling down after sintering is completed;

[0076] S611. Transfer the wafer after the copper sheet sintering is completed to a compression mold, uniformly fill the groove between the non-bonding area on the front side of the wafer and the copper sheet with epoxy resin material, cover the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressing head of the compression mold, the third protective film is made of PVC or PTFE, and the thickness of the third protective film is 10 μm-150 μm, the pressing head of the compression mold is attached to the third protective film, and compression molding is completed in the compression mold. The compression molding temperature is controlled at 150-250° C., the time is 10-100 s, and the pressure is controlled at 10-60 MPa to form epoxy resin sealant 4.

[0077] S612: After the compression molding is completed, the third protective film is removed, and the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0078] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0079] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a dry slurry block 32 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gaps between the chip 2 and the dry slurry block 32 and between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 、 Figure 4 shown.

[0080] Example 3

[0081] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0082] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0083] S2, provide copper sheet 1 for copper cladding, the thickness of the copper sheet is 100-1000 μm, the back of the copper sheet is divided into bonding area and non-bonding area, the non-bonding area of the copper sheet has been etched and formed into a groove, the distance between the front of the copper sheet and the groove bottom is 10-50 μm, the first protective film is pasted on the front of the copper sheet to avoid the front of the copper sheet being polluted in the subsequent process, the thickness of the first protective film is 25-150 μm, and the material of the first protective film is PVC;

[0084] S321, prepare a dry slurry for metal bonding, the dry slurry is prepared by mixing metal powder and a protective agent, the mass fraction of the metal powder in the dry slurry is 50-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder includes silver or copper, and the protective agent is amide or ethylenediamine;

[0085] S322, apply the dry slurry on the transfer film to prepare a dry slurry transfer film with uniform thickness by using a roller;

[0086] S323, remove the dry slurry corresponding to the non-bonding area of the front of the wafer from the transfer film by using a reverse mold jig to obtain a dry slurry block; or, the dry slurry of the non-bonding area of the front of the wafer is cut off by using a laser etching method to obtain a dry slurry block 32;

[0087] S324, accurately align the transfer film and the wafer bonding area through the positioning hole on the transfer film, transfer the dry slurry block to the bonding area of the front of the wafer under the condition of 100-170 ℃ and under the condition that the single dry slurry block is subjected to a pressure of 1-15 MPa, and then remove the transfer film after the transfer is completed;

[0088] S4, transfer the wafer on which the slurry transfer is completed to a sintering jig, the bottom of the sintering jig is covered with a soft material (such as butyl rubber) having supporting property, the sintering jig is designed with an air inlet and an air outlet, the copper sheet in step S2 is accurately placed in the bonding area of the wafer by identifying the identification marks of the copper sheet and the wafer, the bonding area of the copper sheet is attached to the front of the slurry, and the distance between the copper sheets of the adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause short circuit of the bonding area of the wafer;

[0089] S511, cover a second protective film on the first protective film, transfer the wafer with the covered copper sheet and the sintering jig into a sintering machine, press the second protective film by using a sintering pressure head, the material of the second protective film is polytetrafluoroethylene, the thickness of the second protective film is 10-200 μm, protective gas is introduced through the air inlet on the sintering jig, pressure sintering is performed, the pressure of the sintering pressure head pressing the protective film is controlled to be 3-30 MPa, the sintering temperature is controlled to be 200-300 ℃, the sintering time is controlled to be 30-120 s, and vacuum is drawn through the air outlet on the sintering jig during sintering or after sintering is completed.

[0090] S512, slowly cooling the temperature after sintering is completed, and removing the second protective film after the slow cooling is completed.

[0091] S611. Transfer the wafer after the copper sheet sintering is completed to a compression mold, uniformly fill the groove between the non-bonding area on the front side of the wafer and the copper sheet with epoxy resin material, cover the first protective film with a third protective film to prevent the epoxy resin material from adhering to the pressing head of the compression mold, the third protective film is made of PVC or PTFE, and the thickness of the third protective film is 10 μm-150 μm. The pressing head of the compression mold is attached to the third protective film, and compression molding is completed in the compression mold. The compression molding temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa. The epoxy resin material forms epoxy resin sealant 4.

[0092] S612: After the compression molding is completed, the third protective film is removed, and the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0093] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0094] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a dry slurry block 32 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gaps between the chip 2 and the dry slurry block 32 and between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 、 Figure 4 shown.

[0095] Example 4

[0096] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0097] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0098] S2. Provide a copper sheet 1 for copper cladding, wherein the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm. A first protective film is affixed to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet. The thickness of the first protective film is 25 μm-150 μm and the material of the first protective film is PVC;

[0099] S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester;

[0100] S312. Transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying, or screen printing. If the bonding area is smaller than 1 mm x 1 mm, dispensing or spraying is recommended. If the bonding area is larger than 1 mm x 1 mm, dispensing or screen printing is recommended. The coating thickness of the wet slurry is controlled within 10 μm-100 μm.

[0101] S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or excessive reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31;

[0102] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0103] S521. Transfer the copper-covered wafer and the sintering jig into an oven, introduce protective gas through the air inlet of the oven, and perform pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C. and the baking time is controlled at 30-90 minutes. Vacuum is evacuated through the exhaust port of the oven during or after the sintering process.

[0104] S522, slowly cooling down after sintering is completed;

[0105] S611, transfer the wafer with the sintered copper sheet to a compression molding mold, fill the trench between the non-bonding area on the front of the wafer and the copper sheet with epoxy material, cover a third protective film on the first protective film to avoid the epoxy material from sticking to the pressure head of the compression molding mold, the third protective film is made of PVC or PTFE, the thickness of the third protective film is 10-150 μm, the pressure head of the compression molding mold is attached to the third protective film, and the compression molding is completed in the compression molding mold, the compression molding temperature is controlled at 150-250 °C, the time is 10-100 s, and the pressure is 10-60 MPa, and the epoxy material forms an epoxy sealant 4;

[0106] S612, after the compression molding is completed, remove the third protective film, and use mechanical grinding or laser cleaning to clean the excess glue on the copper sheet;

[0107] S7, remove the first protective film, transfer the wafer to a wafer separating machine, and separate the wafer into independent chip assemblies according to the cutting path of the wafer and by using mechanical separation or laser separation;

[0108] S8, dry the separated chip assembly, which includes the copper sheet 1, the chip 2, the wet slurry block 31, and the epoxy sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in Figure 1 、 Figure 2 .

[0109] Example 5

[0110] A method for copper coating on a wafer bonding area, the method comprising the following steps:

[0111] S1, clean the wafer that needs to be coated with copper, clean the organic matter, oxide or other impurities remaining from the previous process that affect the copper coating process, after cleaning, dry the wafer, and then sputter a metal layer on the front of the wafer, the metal layer is made of gold or silver to help improve the bonding stability and reliability, the thickness of the metal layer is 1-10 kÅ, and the bonding area and the non-bonding area on the front of the wafer are formed;

[0112] S2, provide a copper sheet 1 for copper coating, the thickness of the copper sheet is 100-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of the copper sheet has been etched and formed into a trench, the distance between the front of the copper sheet and the bottom of the trench is 10-50 μm, and a first protective film is attached to the front of the copper sheet to avoid contamination of the front of the copper sheet in subsequent processes, the thickness of the first protective film is 25-150 μm, and the first protective film is made of PVC;

[0113] S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester;

[0114] S312. Transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying, or screen printing. If the bonding area is smaller than 1 mm x 1 mm, dispensing or spraying is recommended. If the bonding area is larger than 1 mm x 1 mm, dispensing or screen printing is recommended. The coating thickness of the wet slurry is controlled within 10 μm-100 μm.

[0115] S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm to avoid oxidation or excessive reaction of the slurry, which may affect the subsequent sintering quality. After the semi-curing baking is completed, the wet slurry forms a wet slurry block 31;

[0116] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0117] S511. Cover the first protective film with a second protective film, transfer the copper-covered wafer and the sintering jig into the sintering machine together, press the second protective film with a sintering press head, the second protective film is made of polytetrafluoroethylene, and the thickness of the second protective film is 10 μm-200 μm, and introduce protective gas through the air inlet on the sintering jig to perform pressure sintering. During pressure sintering, the pressure of the sintering press head pressing the protective film is controlled at 3-30 MPa, the sintering temperature is controlled at 200-300°C, and the sintering time is controlled at 30-120 s. Vacuum is evacuated during the sintering process or after sintering is completed through the exhaust port on the sintering jig;

[0118] S512, slowly cooling after sintering is completed, and removing the second protective film after the slow cooling is completed;

[0119] S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the first protective film to the injection mold;

[0120] S622, after the injection mold is pressed together, the epoxy resin sealing material is injected into the groove between the non-bonding area of ​​the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4;

[0121] S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0122] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0123] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a wet slurry block 31 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the wet slurry block 31, the front of the wet slurry block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gap between the chip 2 and the wet slurry block 31 and the gap between the wet slurry block 31 and the copper sheet 1, as shown in FIG. Figure 1 、 Figure 2 shown.

[0124] Example 6

[0125] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0126] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0127] S2. Provide a copper sheet 1 for copper cladding, wherein the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm. A first protective film is affixed to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet. The thickness of the first protective film is 25 μm-150 μm and the material of the first protective film is PVC;

[0128] S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is formed by mixing metal powder and a protective agent, wherein the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises silver or copper, and the protective agent is amide or ethylenediamine;

[0129] S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller;

[0130] S323, using a mold-turning jig, remove the dry slurry corresponding to the non-bonding area of ​​the front side of the wafer from the transfer film to obtain a dry slurry block; alternatively, cut off the dry slurry in the non-bonding area of ​​the front side of the wafer by laser etching to obtain a dry slurry block 32;

[0131] S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa per dry slurry block. After the transfer is completed, peel off the transfer film.

[0132] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0133] S521. Transfer the copper-covered wafer and the sintering jig into an oven, introduce protective gas through the air inlet of the oven, and perform pressure-free sintering. During pressure-free sintering, the baking temperature is controlled at 150-300° C. and the baking time is controlled at 30-90 minutes. Vacuum is evacuated through the exhaust port of the oven during or after the sintering process.

[0134] S522, slowly cooling down after sintering is completed;

[0135] S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the first protective film to the injection mold;

[0136] S622, after the injection mold is pressed together, the epoxy resin sealing material is injected into the groove between the non-bonding area of ​​the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4;

[0137] S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0138] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0139] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a dry slurry block 32 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gaps between the chip 2 and the dry slurry block 32 and between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 、 Figure 4 shown.

[0140] Example 7

[0141] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0142] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0143] S2. Provide a copper sheet 1 for copper cladding, wherein the thickness of the copper sheet is 100 μm-1000 μm, the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and the distance between the front of the copper sheet and the bottom of the groove is 10 μm-50 μm. A first protective film is affixed to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet. The thickness of the first protective film is 25 μm-150 μm and the material of the first protective film is PVC;

[0144] S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is formed by mixing metal powder and a protective agent, wherein the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises silver or copper, and the protective agent is amide or ethylenediamine;

[0145] S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller;

[0146] S323, using a mold-turning jig, remove the dry slurry corresponding to the non-bonding area of ​​the front side of the wafer from the transfer film to obtain a dry slurry block; alternatively, cut off the dry slurry in the non-bonding area of ​​the front side of the wafer by laser etching to obtain a dry slurry block 32;

[0147] S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa per dry slurry block. After the transfer is completed, peel off the transfer film.

[0148] S4. Transfer the wafer after the slurry transfer to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material (such as butyral rubber). The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer.

[0149] S511. Cover the first protective film with a second protective film, transfer the copper-covered wafer and the sintering jig into the sintering machine together, press the second protective film with a sintering press head, the second protective film is made of polytetrafluoroethylene, and the thickness of the second protective film is 10 μm-200 μm, and introduce protective gas through the air inlet on the sintering jig to perform pressure sintering. During pressure sintering, the pressure of the sintering press head pressing the protective film is controlled at 3-30 MPa, the sintering temperature is controlled at 200-300°C, and the sintering time is controlled at 30-120 s. Vacuum is evacuated during the sintering process or after sintering is completed through the exhaust port on the sintering jig;

[0150] S512, slowly cooling after sintering is completed, and removing the second protective film after the slow cooling is completed;

[0151] S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the first protective film to the injection mold;

[0152] S622, after the injection mold is pressed together, the epoxy resin sealing material is injected into the groove between the non-bonding area of ​​the front side of the wafer and the back side of the copper sheet through a press, the injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa, and the epoxy resin material forms epoxy resin sealing material 4;

[0153] S623. After the injection molding is completed, the excess glue on the copper sheet is cleaned by mechanical grinding or laser;

[0154] S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components by mechanical separation or laser separation according to the dicing lanes of the wafer;

[0155] S8, drying the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a dry slurry block 32 and an epoxy resin sealant 4, the front of the chip 2 is connected to the back of the dry slurry block 32, the front of the dry slurry block 32 is connected to the back of the copper sheet 1, and the epoxy resin sealant 4 seals the gaps between the chip 2 and the dry slurry block 32 and between the dry slurry block 32 and the copper sheet 1, as shown in FIG. Figure 3 、 Figure 4 shown.

[0156] Example 8

[0157] A method for copper coating a wafer bonding area, the method comprising the following steps:

[0158] S1. Clean the wafer that needs copper cladding to remove organic matter, oxides or other impurities that affect the copper cladding process left in the previous process. After cleaning, dry the wafer. After drying, sputter a metal layer on the front of the wafer. The metal layer is made of gold or silver to help improve bonding stability and reliability. The thickness of the metal layer is 1-10 kÅ, forming a bonding area and a non-bonding area on the front of the wafer.

[0159] S2. Provide a copper sheet for copper cladding, the thickness of the copper sheet being 100 μm to 1000 μm, the back of the copper sheet being divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet having been etched to form a groove, the distance between the front of the copper sheet and the bottom of the groove being 10 μm to 50 μm, and affix a first protective film to the front of the copper sheet to prevent subsequent processes from contaminating the front of the copper sheet, the thickness of the first protective film being 25 μm to 150 μm, and the material of the first protective film being PVC;

[0160] S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-90%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester;

[0161] S312. Transfer the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying, or screen printing. If the bonding area is smaller than 1 mm x 1 mm, dispensing or spraying is recommended. If the bonding area is larger than 1 mm x 1 mm, dispensing or screen printing is recommended. The coating thickness of the wet slurry is controlled within 10 μm-100 μm.

[0162] S313, place the wafer coated with wet paste into an oven for semi-curing baking, control the semi-curing baking temperature at 100-180℃, control the semi-curing baking time at 30-90 minutes, control the oxygen content in the oven at less than 500ppm, avoid oxidation or excessive reaction of the paste, affect the quality of subsequent sintering, after the semi-curing baking is completed, the wet paste forms a wet paste block 31;

[0163] S4, transfer the wafer after the paste transfer to a sintering jig, the bottom of the sintering jig is covered with a soft material (such as butyl rubber) with support, the sintering jig is designed with an air inlet and an air outlet, the copper sheet of step S2 is accurately placed on the bonding area of the wafer by identifying the identification marks of the copper sheet and the wafer, the bonding area of the copper sheet is attached to the front of the paste, and the distance between the copper sheets of the adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause short circuit of the bonding area of the wafer;

[0164] S521, transfer the wafer covered with the copper sheet and the sintering jig to the oven, pass the protective gas through the air inlet on the oven, and perform pressureless sintering, during the pressureless sintering, control the baking temperature at 150-300℃, control the baking time at 30-90 minutes, and perform vacuumizing through the air outlet on the oven during the sintering process or after the sintering is completed;

[0165] S522, slow cooling after sintering is completed;

[0166] S621, transfer the wafer after the copper sheet sintering to an injection mold, the injection mold is attached to the first protective film;

[0167] S622, after the injection mold is pressed and completed, the epoxy resin sealing material is injected into the groove between the non-bonding area of the front of the wafer and the back of the copper sheet through the press, the injection temperature is controlled at 150-250℃, the time is controlled at 10-100s, and the pressure is controlled at 10-60MPa, the epoxy resin material forms an epoxy resin sealing material 4;

[0168] S623, after the injection is completed, the overflow glue on the copper sheet is cleaned by mechanical grinding or laser cleaning;

[0169] S7, remove the first protective film, transfer the wafer to a wafer separating machine, separate the wafer into independent chip assemblies according to the cutting path of the wafer and by mechanical separation or laser separation;

[0170] S8, dry the separated chip assembly, the chip assembly includes a copper sheet 1, a chip 2, a wet paste block 31, and an epoxy resin sealing material 4, the front of the chip 2 is connected to the back of the wet paste block 31, the front of the wet paste block 31 is connected to the back of the copper sheet 1, and the epoxy resin sealing material 4 seals the gap between the chip 2 and the wet paste block 31 and the gap between the wet paste block 31 and the copper sheet 1, as shown in Figure 1 ,Figure 2 shown.

[0171] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for copper coating in a wafer bonding area, characterized in that The method comprises the following steps: S1. Clean the wafer to be copper-clad. After cleaning, dry the wafer. After drying, sputter a metal layer on the front side of the wafer to form a bonding area and a non-bonding area on the front side of the wafer. The metal layer is made of gold or silver and has a thickness of 1-10 kÅ. S2. Providing a copper sheet for copper cladding, wherein the back of the copper sheet is divided into a bonding area and a non-bonding area, the non-bonding area of ​​the copper sheet has been etched to form a groove, and a first protective film is applied to the front of the copper sheet; S3, preparing a metal bonding slurry and transferring the slurry to the bonding area of ​​the wafer; Step S3 is specifically as follows: S311. Prepare a wet slurry for metal bonding, wherein the wet slurry is formed by mixing metal powder and a suspending agent, wherein the mass fraction of the metal powder in the wet slurry is 50%-95%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises one of silver, copper, palladium, rhodium, nickel, or a mixture thereof, and the suspending agent comprises ethylene glycol, tridecanol, a halogenated alcohol, or a dibasic ester; S312, transferring the wet slurry to the bonding area on the front side of the wafer by dispensing, spraying or screen printing, and controlling the coating thickness of the wet slurry to be 10 μm-100 μm; S313, placing the wafer coated with the wet slurry in an oven for semi-curing baking, wherein the semi-curing baking temperature is controlled at 100-180° C., the semi-curing baking time is controlled at 30-90 minutes, and the oxygen content in the oven is controlled at less than 500 ppm. After the semi-curing baking is completed, the wet slurry forms a wet slurry block; Alternatively, step S3 is specifically as follows: S321. Prepare a dry slurry for metal bonding, wherein the dry slurry is formed by mixing metal powder and a protective agent, wherein the mass fraction of the metal powder in the dry slurry is 50%-99%, the particle size of the metal powder is 10 nm-100 μm, the metal powder comprises silver or copper, and the protective agent is amide or ethylenediamine; S322, applying the dry slurry on the transfer film, and preparing a dry slurry transfer film with uniform thickness by a roller; S323, using a mold-turning jig, remove the dry slurry corresponding to the non-bonding area of ​​the front side of the wafer from the transfer film to obtain a dry slurry block; or, using a laser etching method, cut away the dry slurry in the non-bonding area of ​​the front side of the wafer to obtain a dry slurry block; S324. Accurately align the transfer film and the wafer bonding area through the positioning holes on the transfer film, transfer the dry slurry block to the bonding area on the front side of the wafer at a temperature of 100-170° C. and a pressure of 1-15 MPa per dry slurry block. After the transfer is completed, peel off the transfer film. S4. The wafer after the slurry transfer is transferred to a sintering jig. The bottom of the sintering jig is covered with a supportive soft material. The sintering jig is designed with an air inlet and an exhaust port. The copper sheet from step S2 is accurately placed on the bonding area of ​​the wafer by aligning the copper sheet and the wafer identification mark. The bonding area of ​​the copper sheet is in contact with the front side of the slurry. The distance between the copper sheets in adjacent bonding areas of the wafer is controlled to be greater than the distance that can cause a short circuit in the bonding area of ​​the wafer. S5, sintering the wafer covered with the copper sheet; S6, evenly filling the epoxy resin material between the non-bonding area on the front side of the wafer and the groove between the copper sheet and performing plastic sealing; S7, removing the first protective film, transferring the wafer to a wafer separator, and separating the wafer into independent chip components according to the dicing lanes of the wafer; S8. Dry and separate the chip assembly, which includes a copper sheet, a chip, a slurry block and an epoxy resin sealant. The front of the chip is connected to the back of the slurry block, and the front of the slurry block is connected to the back of the copper sheet. The epoxy resin sealant seals the gaps between the chip and the slurry block and between the slurry block and the copper sheet.

2. The method for copper coating in the wafer bonding area according to claim 1, wherein: Step S5 is specifically as follows: S511. Cover the first protective film with a second protective film, transfer the copper-covered wafer and the sintering jig into a sintering machine, press the second protective film with a sintering press head, introduce protective gas through the air inlet on the sintering jig, perform pressure sintering, and evacuate the film through the exhaust port on the sintering jig during or after sintering. The second protective film is made of polytetrafluoroethylene and has a thickness of 10 μm-200 μm. During pressure sintering, the pressure of the sintering press head pressing the protective film is controlled at 3-30 MPa, the sintering temperature is controlled at 200-300°C, and the sintering time is controlled at 30-120 s. S512, slowly cooling the temperature after sintering is completed, and removing the second protective film after the slow cooling is completed.

3. The method for copper coating in the wafer bonding area according to claim 1, wherein: Step S5 is specifically as follows: S521. Transfer the copper-covered wafer and the sintering jig into an oven. Introduce protective gas through the air inlet of the oven for pressure-free sintering. Vacuum the oven through the exhaust port during or after sintering. During pressure-free sintering, control the baking temperature at 150-300° C. and the baking time at 30-90 minutes. S522, slowly cool down after sintering is completed.

4. The method for copper coating in the wafer bonding area according to claim 1, wherein: Step S6 is specifically as follows: S611. Transfer the wafer after the copper sheet sintering is completed to a compression mold, uniformly fill the groove between the non-bonding area on the front side of the wafer and the copper sheet with epoxy resin material, cover the first protective film with a third protective film, and place the pressing head of the compression mold on the third protective film. Compression molding is completed in the compression mold. The compression molding temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa. The material of the third protective film is PVC or PTFE, and the thickness of the third protective film is 10 μm-150 μm. S612. After the compression molding is completed, the third protective film is removed, and the excess glue on the copper sheet is cleaned by mechanical grinding or laser.

5. The method for copper coating in the wafer bonding area according to claim 1, wherein: Step S6 is specifically as follows: S621, transferring the wafer after the copper sheet sintering to an injection mold, and attaching the first protective film to the injection mold; S622. After the injection mold is pressed together, the epoxy resin sealing material is injected into the groove between the non-bonding area on the front side of the wafer and the copper sheet through a press. The injection temperature is controlled at 150-250° C., the time is 10-100 seconds, and the pressure is 10-60 MPa. S623. After injection molding is completed, use mechanical grinding or laser to clean the excess glue on the copper sheet.

6. The method for copper coating in the wafer bonding area according to claim 1, wherein: In step S2 , the thickness of the copper sheet is 100 μm-1000 μm, and the distance between the front surface of the copper sheet and the bottom of the groove is 10 μm-50 μm.

7. The method for copper coating in the wafer bonding area according to claim 1, wherein: In step S2 , the thickness of the first protective film is 25 μm-150 μm, and the material of the first protective film is PVC.

8. The method for copper coating in the wafer bonding area according to claim 1, wherein: In step S7 , the wafer is separated into individual chips by mechanical separation or laser separation according to the dicing lines of the wafer.

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