Low cost stable wafer level metal diffusion bonding method and semiconductor wafer

Abstract

The application discloses a low-cost stable wafer-level metal diffusion bonding method and a semiconductor wafer. The wafer-level metal diffusion bonding method comprises the following steps: forming a first bonding metal layer on a first surface of a first wafer, wherein the first bonding metal layer comprises a first deformation layer metal and a first passivation layer metal; forming a second bonding metal layer on a second surface of a second wafer, wherein the second bonding metal layer comprises a second deformation layer metal and a second passivation layer metal; and performing plasma surface activation treatment on at least the first passivation layer metal and the second passivation layer metal to bond the first bonding metal layer and the second bonding metal layer together, and combining the first passivation layer metal and the second passivation layer metal into one body by means of hot-press bonding. The wafer-level metal diffusion bonding method provided by the application overcomes the problem of surface oxidation of bonding metal layers in Al-Al or Cu-Cu bonding, and reduces the bonding temperature.

Description

Technical Field

[0001] This invention relates to a wafer bonding method, and more particularly to a low-cost and stable wafer-level metal diffusion bonding method and semiconductor wafer, belonging to the field of electronic science and technology. Background Technology

[0002] In recent years, semiconductor packaging technology has evolved from two-dimensional packaging to three-dimensional stacking, and is developing towards lower cost, higher performance, higher integration, smaller size, and lower power consumption. Wafer-level bonding technology plays a crucial role in the packaging processes of semiconductor devices and integrated circuits. More than half of packaging technologies utilize wafer-level bonding processes. Besides its widespread application in advanced packaging processes, wafer-level bonding is also used in fundamental processes such as the packaging and manufacturing of MEMS devices, substrate transfer for high-brightness LEDs, and the fabrication of CMOS image sensors.

[0003] Wafer-level bonding methods can be broadly categorized into two types: interlayer-less wafer bonding and interlayer-based wafer bonding. Interlayer-less wafer bonding can be further divided into: direct bonding (where two materials are bonded together without an interlayer or external force field, typically requiring high-temperature annealing) and anodic bonding (where an electric field is applied between glass and metal foils to achieve bonding). Interlayer-based wafer bonding can be further divided into: metal diffusion bonding (using diffusion between metals to achieve bonding, such as Au-Au, Cu-Cu, Al-Al) and eutectic bonding (where two or more bonding materials form a eutectic alloy at a specific temperature to achieve bonding, such as Au-Sn), etc.

[0004] Common diffusion bonding methods include Au-Au bonding, Cu-Cu bonding, and Al-Al bonding. Au, Cu, and Al are frequently chosen because they are easily deformed and have good ductility, allowing for increased bonding rates by increasing the metal thickness. For Au-Au bonding, Au's fast diffusion rate makes it an ideal material. However, to improve the bonding rate, the Au film thickness must be increased, thus raising the cost.

[0005] Although Cu-Cu bonding and Al-Al bonding are less expensive, oxide layers easily form on their surfaces after Cu or Al deposition, which severely affects the bonding success rate. Secondly, the high pressure used in the vapor phase cleaning process to remove surface oxides during bonding can cause Cu or Al to break, and the bonding temperature is also high. Summary of the Invention

[0006] The main objective of this invention is to provide a low-temperature, low-cost, and stable wafer-level metal diffusion bonding method and semiconductor wafer to overcome the shortcomings of the prior art.

[0007] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0008] This invention provides a low-cost and stable wafer-level metal diffusion bonding method, comprising:

[0009] A first bonding metal layer is formed on a first surface of a first wafer. The first bonding metal layer includes a first deformation layer metal formed on the first surface and a first passivation layer metal formed on the surface of the first deformation layer metal.

[0010] A second bonding metal layer is formed on the second surface of the second wafer. The second bonding metal layer includes a second deformation layer metal formed on the second surface and a second passivation layer metal formed on the surface of the second deformation layer metal.

[0011] At least the first passivation layer metal and the second passivation layer metal are subjected to plasma surface activation treatment;

[0012] The first bonding metal layer and the second bonding metal layer are bonded together, and the first passivation layer metal and the second passivation layer metal are bonded together by hot pressing.

[0013] In one specific implementation, the thickness of the first passivation layer metal and the second passivation layer metal is 10-50 nm.

[0014] In one specific implementation, the materials of the first passivation layer metal and the second passivation layer metal include gold.

[0015] In one specific implementation, the plasma used in the plasma surface activation treatment includes plasma of inert gas.

[0016] In one specific implementation, the plasma surface activation treatment time is 0-5 min, and the plasma power is 0-200 W. Under these specific conditions, the activation of the passivation layer metal surface can be achieved.

[0017] In one specific implementation, the first deformation layer metal and the second deformation layer metal include copper or aluminum.

[0018] In one specific implementation, the first deformation layer metal and the second deformation layer metal are made of the same material.

[0019] In one specific implementation, the thickness of the first deformation layer metal and the second deformation layer metal is 1-2 μm.

[0020] In a specific implementation example, the wafer-level metal diffusion bonding method specifically includes: hot-press bonding the first passivation layer metal and the second passivation layer metal together in a vacuum environment at 150-300℃, wherein the hot-press bonding pressure is 0.4-2MPa and the time is 30-50min.

[0021] In a specific implementation example, the wafer-level metal diffusion bonding method further includes: firstly forming a dielectric layer, a metal adhesion layer, and a diffusion barrier layer sequentially on the first surface of the first wafer and the second surface of the second wafer, and then forming a first bonding metal layer or a second bonding metal layer on the surface of the diffusion barrier metal layer.

[0022] In one specific implementation, the dielectric layer is made of silicon nitride.

[0023] In one specific implementation, the thickness of the dielectric layer is 100-500 nm.

[0024] In one specific implementation, the metal adhesive layer is made of titanium.

[0025] In one specific implementation, the thickness of the metal adhesion layer is 10-50 nm.

[0026] In one specific implementation, the diffusion barrier layer is made of platinum and has a thickness of 10-50 nm.

[0027] This invention also provides a semiconductor wafer comprising:

[0028] The first wafer and the first deformation layer and the first passivation layer are sequentially stacked on the first surface of the first wafer;

[0029] The second wafer and the second deformation layer and the second passivation layer are sequentially stacked on the second surface of the second wafer;

[0030] The first passivation layer and the second passivation layer are combined.

[0031] In one specific implementation, the first passivation layer and the second passivation layer are bonded together.

[0032] In one specific implementation, the thickness of the first passivation layer and the second passivation layer is 10-50 nm.

[0033] In one specific implementation, the materials of the first passivation layer and the second passivation layer include gold.

[0034] In one specific implementation, the first deformation layer and the second deformation layer comprise copper or aluminum.

[0035] In one specific implementation case, the first deformation layer and the second deformation layer are made of the same material.

[0036] In one specific implementation, the thickness of the first deformation layer and the second deformation layer is 1-2 μm.

[0037] In one specific implementation, the first surface of the first wafer is further provided with a first dielectric layer, a first metal adhesion layer and a first diffusion barrier layer stacked sequentially, and the first deformation layer is disposed on the first diffusion barrier layer.

[0038] In one specific implementation, the material of the first dielectric layer includes silicon nitride.

[0039] In one specific implementation, the thickness of the first dielectric layer is 100-500 nm.

[0040] In one specific implementation, the material of the first metal adhesion layer includes titanium.

[0041] In one specific implementation, the thickness of the first metal adhesion layer is 10-50 nm.

[0042] In one specific implementation, the material of the first diffusion barrier layer includes platinum metal, and the thickness of the first diffusion barrier layer is 10-50 nm.

[0043] In one specific implementation, the second surface of the second wafer is further provided with a second dielectric layer, a second metal adhesion layer and a second diffusion barrier layer stacked sequentially, and the second deformation layer is disposed on the second diffusion barrier layer.

[0044] In one specific implementation, the material of the second dielectric layer includes silicon nitride.

[0045] In one specific implementation, the thickness of the second dielectric layer is 100-500 nm.

[0046] In one specific implementation, the second metal adhesion layer is made of titanium.

[0047] In one specific implementation, the thickness of the second metal adhesion layer is 10-50 nm.

[0048] In one specific implementation, the material of the second diffusion barrier layer includes platinum metal, and the thickness of the second diffusion barrier layer is 10-50 nm.

[0049] This invention is an improvement and upgrade to existing metal diffusion bonding technology, solving the problems existing in the prior art. Compared with the prior art, the advantages of this invention include:

[0050] 1) The present invention provides a low-temperature, low-cost, and stable wafer-level metal diffusion bonding method. This method deposits Au as a metal passivation layer on a metal deformation layer Cu or Al, which can effectively reduce the temperature of Cu-Cu or Al-Al bonding. At the same time, compared with Au-Au bonding, it can effectively reduce the amount of Au used and reduce the bonding cost.

[0051] 2) The low-temperature, low-cost, and stable wafer-level metal diffusion bonding method provided in this embodiment of the invention can effectively avoid the oxidation of Cu or Al by depositing an Au surface passivation layer in situ, while controlling the thickness of the Au surface passivation layer to promote the diffusion of Cu or Al, thereby obtaining better bonding effect at a lower bonding temperature.

[0052] 3) The low-temperature, low-cost, and stable wafer-level metal diffusion bonding method provided in this embodiment of the invention can effectively reduce bonding difficulty and improve bonding success by controlling the thickness of the deformed layer metal;

[0053] 4) The embodiment of the present invention provides a low-temperature, low-cost, and stable wafer-level metal diffusion bonding method. The bonded material has good thermal stability and will not exhibit the phenomenon of eutectic bonding undergoing co-melting and recrystallization at high temperatures. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the structure of the wafer to be bonded in a low-cost and stable wafer-level metal diffusion bonding method provided in a typical embodiment of the present invention;

[0055] Figures 2-6 This is a schematic diagram of the process structure of a low-cost and stable wafer-level metal diffusion bonding method provided in a typical embodiment of the present invention.

[0056] Figure 7 This is a SEM image of the bonding surface of the wafer after bonding in Embodiment 1 of the present invention. Detailed Implementation

[0057] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0058] This invention provides a low-cost and stable wafer-level metal diffusion bonding method. By passivating the surface of Cu-Cu or Al-Al bonding layers with a gold passivation layer (or surface layer), Cu or Al oxidation is prevented, Cu diffusion is promoted, and the amount of Au used is reduced, thereby achieving a low-temperature, low-cost, and high-quality bonding effect.

[0059] The present invention provides a low-cost and stable wafer-level metal diffusion bonding method. In diffusion bonding, the bonding metal layer is divided into two systems: 1) surface layer (i.e., the aforementioned passivation layer), which is required to be smooth and clean to provide conditions for the diffusion of metal elements; 2) deformation layer, which refers to the metal material layer below the surface layer, which is at least used for plastic deformation to resist surface warping and surface unevenness.

[0060] The present invention provides a low-cost and stable wafer-level metal diffusion bonding method. After depositing a certain thickness of Cu or Al as a deformation layer (or extension layer), a thin layer of Au is deposited as a passivation layer. This can prevent the surface oxidation of Cu or Al, improve the diffusion rate, and reduce the amount of Au used, thereby reducing costs.

[0061] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the methods used to form metal layers and other structural layers in the embodiments of the present invention are known to those skilled in the art.

[0062] Please see Figure 1 The present invention provides a wafer structure to be bonded, comprising a wafer to be bonded #1 (i.e., the aforementioned first wafer, hereinafter the same) and a dielectric layer, an adhesion layer / diffusion barrier layer, a Cu or Al deformation layer and an Au passivation layer sequentially stacked on the surface of the wafer to be bonded #1, wherein the dielectric layer is made of silicon nitride (SiN). x The dielectric layer has a thickness of 100-500 nm, the adhesive layer is made of titanium and has a thickness of 10-50 nm, the diffusion barrier layer is made of platinum and has a thickness of 50-100 nm, the Cu or Al deformation layer has a thickness of 1-2 μm, and the Au passivation layer has a thickness of 10-50 nm. It should be noted that setting the thickness of the Au passivation layer to 10-50 nm can simultaneously achieve the effects of surface passivation and diffusion promotion. Also, if the thickness of the deformation layer is too small, the bonding effect will be poor, while if the thickness of the deformation layer is too large, the cost will increase. Therefore, in this embodiment of the invention, the thickness of the Cu or Al deformation layer is 1-2 μm.

[0063] Please see Figures 2-6 A low-cost and stable wafer-level metal diffusion bonding method may include the following steps:

[0064] 1) A dielectric layer is deposited on the first surface of the wafer #1 to be bonded. The dielectric layer can prevent metal from diffusing to the wafer #1. The technique for forming the dielectric layer can be: PECVD (plasma-enhanced chemical vapor deposition), LPCVD (low-pressure chemical vapor deposition), ALD (atomic layer deposition), MOCVD (metal-organic chemical vapor deposition), etc. The material of the dielectric layer can be SiN. x SiO2, etc.;

[0065] 2) After the dielectric layer is deposited, metal deposition techniques such as magnetron sputtering, electron beam evaporation, and electroplating are used to sequentially deposit an adhesion layer metal (Ti or Cr) and a diffusion barrier layer metal (Ni or Pt) on the dielectric layer, thereby forming an adhesion layer / diffusion barrier layer.

[0066] 3) A Cu or Al deformation layer is deposited on the adhesion layer / diffusion barrier layer using metal deposition techniques such as magnetron sputtering, electron beam evaporation, and electroplating;

[0067] 4) To prevent oxidation of the Cu / Al deformation layer surface, a 10-50 nm thick layer of Au metal is deposited on the Cu / Al deformation layer surface as a passivation layer. The passivation layer metal is then subjected to plasma surface activation treatment to form the first wafer structure to be bonded. The plasma surface activation treatment uses inert gas plasma, the plasma surface activation treatment time is 0-5 min, the plasma power is 0-200 W, and the plasma surface activation treatment can achieve surface activation.

[0068] 5) Using the same process as steps 1)-4, a dielectric layer, an adhesion / diffusion barrier layer, a Cu or Al deformation layer, and an Au passivation layer are sequentially formed on the second surface of the wafer to be bonded #2 (i.e., the aforementioned second wafer), thereby forming the second wafer structure to be bonded; then, the Au passivation layer of the first wafer structure to be bonded is bonded to the Au passivation layer of the second wafer structure to be bonded, and hot-press bonding is performed in a high-pressure vacuum bonding machine, wherein the hot-press bonding temperature is 150℃-300℃, the pressure is 0.4MPa-2MPa, and the time is 30min-50min, thereby at least bonding the wafers to be bonded #1 and #2 into one unit, and the structure of the semiconductor wafer formed by bonding is as follows. Figure 6 As shown.

[0069] The following will provide a further explanation of the technical solution, its implementation process, and its principles, in conjunction with specific embodiments.

[0070] Example 1

[0071] This embodiment involves bonding two Si wafers, which can be used for experimental verification before the actual wafer bonding.

[0072] A low-cost and stable wafer-level metal diffusion bonding method includes the following steps:

[0073] Step 1: Substrate Acquisition and Cleaning

[0074] Organic cleaning: First, place two 4-inch Si wafers in acetone solution and sonicate for 10 minutes, then sonicate in isopropanol solution for 10 minutes, then sonicate in ultrapure water for 5 minutes. Repeatedly rinse with ultrapure water to remove residual acetone and isopropanol solution, and finally use nitrogen to blow dry to remove surface organic matter.

[0075] Inorganic cleaning: Immerse two 4-inch Si wafers in a solution of HF:H2O = 1:10 for 1 minute to remove surface oxides;

[0076] Step 2: Deposition of the dielectric layer

[0077] In a PECVD system, 500nm SiN is deposited on a cleaned Si wafer. x A dielectric layer is used to prevent the metal from diffusing to one side of the Si wafer;

[0078] Step 3: Sequentially deposit the metal adhesion layer, diffusion barrier layer, deformation layer, and passivation layer.

[0079] Using magnetron sputtering technology, two SiN deposited layers were sputtered separately. x Ti metal adhesion layer / Pt diffusion barrier layer / Cu deformation layer / Au passivation layer with thicknesses of 50nm / 100nm / 1000nm / 10nm are sequentially sputtered onto a 4-inch Si wafer with dielectric layer.

[0080] Step 4: Plasma surface activation treatment

[0081] The Si wafer after sputtering metal was placed in an ICP chamber and surface activated for 2 minutes using Ar plasma with a power of 100W.

[0082] Step 5: Metal diffusion bonding

[0083] The Au passivation layers on two surface-activated Si wafers to be bonded were attached together and placed in a bonding machine. Hot-press bonding was performed for 45 minutes under a pressure of 1.3 MPa and a vacuum environment of 150°C, thereby bonding the two Si wafers into one. The SEM image of the cross-section of the bonding surface of the two Si wafers is shown below. Figure 7 As shown.

[0084] Example 2

[0085] This embodiment can be used for the fabrication of vertical GaN-based LEDs.

[0086] A method for fabricating a vertical GaN-based LED includes the following steps:

[0087] Step 1: Wafer Acquisition and Cleaning

[0088] Organic cleaning: First, place the GaN-based LED and Si wafer with ohmic contacts on the sapphire substrate in acetone solution for ultrasonic cleaning for 10 minutes, then in isopropanol solution for 10 minutes, and then in ultrapure water for ultrasonic cleaning for 5 minutes. Repeatedly rinse with ultrapure water to remove residual acetone and isopropanol solution, and finally use nitrogen to blow dry to remove surface organic matter.

[0089] Step 2: Sequentially deposit the metal adhesion layer, diffusion barrier layer, deformation layer, and passivation layer.

[0090] Using magnetron sputtering technology, Ti metal adhesion layer / TiW diffusion barrier layer / Al deformation layer / Au passivation layer with thicknesses of 50nm / 100nm / 800nm / 30nm were sequentially sputtered on GaN-based LEDs and Si wafers, respectively.

[0091] Step 3: Plasma Surface Activation Treatment

[0092] The GaN-based LEDs with sputtered metal and the Si wafers were placed in an ICP chamber and surface activated for 1 minute using Ar plasma with a power of 200W.

[0093] Step 4: Metal diffusion bonding

[0094] The surface-activated GaN-based LED is bonded to two Au passivation layers in a Si wafer and placed in a bonding machine for hot-press bonding at 1.5 MPa pressure and 300°C vacuum for 30 minutes to form a vertical GaN-based LED.

[0095] Example 3

[0096] A method for preparing N-polar GaN based on substrate lift-off includes the following steps:

[0097] Step 1: Wafer Acquisition and Cleaning

[0098] Organic cleaning: First, the Ga polar GaN epitaxial wafer based on Si substrate and the Si wafer are placed in acetone solution for ultrasonic cleaning for 10 min, then in isopropanol solution for 10 min, and then placed in ultrapure water for ultrasonic cleaning for 5 min. Repeatedly rinse with ultrapure water to remove residual acetone and isopropanol solution, and finally use nitrogen to blow dry to remove surface organic matter.

[0099] Inorganic cleaning: The Ga polar GaN epitaxial wafer based on Si substrate was immersed in a solution of HCl:H2O 1:5 for 2 min to remove surface oxides; the Si wafer was immersed in a solution of HF:H2O = 1:10 for 1 min to remove surface oxides.

[0100] Step 2: Deposition of the dielectric layer

[0101] In the PECVD system, a 400 nm SiO2 dielectric layer is deposited on the cleaned Ga polar GaN epitaxial wafer and Si wafer to prevent metal diffusion to one side of the Si wafer and Ga polar GaN epitaxial wafer.

[0102] Step 3: Sequentially deposit the metal adhesion layer, diffusion barrier layer, deformation layer, and passivation layer.

[0103] Using magnetron sputtering technology, Ti metal adhesion layer / Pt diffusion barrier layer / Cu deformation layer / Au passivation layer with thicknesses of 50nm / 200nm / 1000nm / 50nm are sequentially sputtered on Si wafers and Ga polar GaN epitaxial wafers, respectively.

[0104] Step 4: Plasma surface activation treatment

[0105] The sputtered metal Si wafer and Ga polar GaN epitaxial wafer were placed in an ICP chamber and surface activated for 5 min with 50W Ar plasma.

[0106] Step 5: Metal diffusion bonding

[0107] The surface-activated Si wafer was bonded to the Au passivation layer on the Ga polar GaN epitaxial wafer and placed in a bonding machine for hot-press bonding at 1 MPa pressure and 300°C vacuum for 50 minutes.

[0108] This invention provides a diffusion bonding method for gold passivation Cu-Cu / Al-Al bonding with good bonding effect and low cost. The key point of this method is to deposit an additional thin layer of Au as a surface passivation layer (10-50nm) on the basis of forming a thick layer of Cu metal or Al metal (1-2μm) on Cu-Cu bonding or Al-Al bonding to prevent oxidation of Cu / Al surface, thereby achieving good bonding effect.

[0109] The main innovation of the low-temperature, low-cost, and stable wafer-level metal diffusion bonding method provided by this invention lies in the in-situ deposition of an Au passivation layer on the surface of conventional Cu-Cu or Al-Al bonding metals. This eliminates the disadvantage that Cu and Al surfaces are easily oxidized and affect bonding. Furthermore, an appropriate Au passivation layer thickness can promote the diffusion of Cu and Al, thereby reducing the bonding temperature. This invention uses a specified Au passivation layer thickness so that it can both passivate and promote the diffusion of Cu and Al. The final selected Au passivation layer thickness is 10-50 nm.

[0110] Compared with existing direct bonding processes, the present invention provides a low-cost and stable wafer-level metal diffusion bonding method that uses a Cu / Al deformation layer of a specified thickness to undergo a certain deformation during bonding, thereby reducing the bonding difficulty.

[0111] Compared with existing eutectic bonding processes (such as Au-Sn bonding), the present invention provides a low-cost and stable wafer-level metal diffusion bonding method that uses diffusion bonding to achieve bonding. The resulting thermal stability is better and the phenomenon of eutectic bonding undergoing co-melting and recrystallization at high temperatures will not occur.

[0112] Compared with existing Au-Au bonding in diffusion bonding, the present invention provides a low-cost and stable wafer-level metal diffusion bonding method that reduces the amount of Au used and lowers costs.

[0113] Compared with existing Cu-Cu and Al-Al diffusion bonding methods, the present invention provides a low-cost and stable wafer-level metal diffusion bonding method that avoids the oxidation of Cu or Al surfaces by using an Au surface passivation layer, thereby achieving better bonding results.

[0114] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A wafer-level metal diffusion bonding method, characterized in that... include: A first bonding metal layer is formed on a first surface of a first wafer. The first bonding metal layer includes a first deformation layer metal formed on the first surface and a first passivation layer metal formed on the surface of the first deformation layer metal. A second bonding metal layer is formed on the second surface of the second wafer. The second bonding metal layer includes a second deformation layer metal formed on the second surface and a second passivation layer metal formed on the surface of the second deformation layer metal. The first deformation layer metal and the second deformation layer metal include copper or aluminum. The first passivation layer metal and the second passivation layer metal are made of gold. At least the first passivation layer metal and the second passivation layer metal are subjected to plasma surface activation treatment. The plasma used for plasma surface activation treatment includes inert gas plasma. The plasma surface activation treatment time is 0-5 min and the plasma power is 0-200W. The first bonding metal layer and the second bonding metal layer are bonded together, and the first passivation layer metal and the second passivation layer metal are hot-pressed together in a vacuum environment at 150-300℃, wherein the hot-pressing pressure is 0.4-2MPa and the time is 30-50min.

2. The wafer-level metal diffusion bonding method according to claim 1, characterized in that: The thickness of the first passivation layer metal and the second passivation layer metal is 10-50 nm.

3. The wafer-level metal diffusion bonding method according to claim 1, characterized in that: The first deformation layer metal and the second deformation layer metal are made of the same material.

4. The wafer-level metal diffusion bonding method according to claim 1 or 3, characterized in that: The thickness of the first deformation layer metal and the second deformation layer metal is 1-2 mm.

5. The wafer-level metal diffusion bonding method according to claim 1, characterized in that... Also includes: First, a dielectric layer, a metal adhesion layer, and a diffusion barrier layer are sequentially formed on the first surface of the first wafer and the second surface of the second wafer. Then, a first bonding metal layer or a second bonding metal layer is formed on the surface of the diffusion barrier layer.

6. The wafer-level metal diffusion bonding method according to claim 5, characterized in that: The dielectric layer is made of silicon nitride.

7. The wafer-level metal diffusion bonding method according to claim 5, characterized in that: The thickness of the dielectric layer is 100-500 nm.

8. The wafer-level metal diffusion bonding method according to claim 5, characterized in that: The material of the metal adhesion layer includes titanium.

9. The wafer-level metal diffusion bonding method according to claim 5, characterized in that: The thickness of the metal adhesion layer is 10-50 nm.

10. The wafer-level metal diffusion bonding method according to claim 5, characterized in that: The diffusion barrier layer is made of platinum and has a thickness of 50-100 nm.

11. A semiconductor wafer, characterized in that... include: The first wafer and the first deformation layer and the first passivation layer are sequentially stacked on the first surface of the first wafer; The second wafer and the second deformation layer and the second passivation layer are sequentially stacked on the second surface of the second wafer. The first passivation layer and the second passivation layer are made of gold, and the first deformation layer and the second deformation layer are made of copper or aluminum. The semiconductor wafer is formed by bonding using the wafer-level metal diffusion bonding method according to any one of claims 1-10, wherein the first passivation layer and the second passivation layer are bonded together.

12. The semiconductor wafer according to claim 11, characterized in that: The first passivation layer and the second passivation layer are bonded together.

13. The semiconductor wafer according to claim 11, characterized in that: The thickness of the first passivation layer and the second passivation layer is 10-50 nm.

14. The semiconductor wafer according to claim 11, characterized in that: The first deformation layer and the second deformation layer are made of the same material.

15. The semiconductor wafer according to claim 11, characterized in that: The thickness of the first deformation layer and the second deformation layer is 1-2 mm.

16. The semiconductor wafer according to claim 11, characterized in that: The first surface of the first wafer is further provided with a first dielectric layer, a first metal adhesion layer and a first diffusion barrier layer stacked sequentially, and the first deformation layer is disposed on the first diffusion barrier layer.

17. The semiconductor wafer according to claim 16, characterized in that: The material of the first dielectric layer includes silicon nitride.

18. The semiconductor wafer according to claim 16, characterized in that: The thickness of the first dielectric layer is 100-500 nm.

19. The semiconductor wafer according to claim 16, characterized in that: The first metal adhesion layer is made of titanium.

20. The semiconductor wafer according to claim 16, characterized in that: The thickness of the first metal adhesion layer is 10-50 nm.

21. The semiconductor wafer according to claim 16, characterized in that: The first diffusion barrier layer is made of platinum and has a thickness of 10-50 nm.

22. The semiconductor wafer according to claim 11, characterized in that: The second surface of the second wafer is further provided with a second dielectric layer, a second metal adhesion layer and a second diffusion barrier layer stacked sequentially, and the second deformation layer is disposed on the second diffusion barrier layer.

23. The semiconductor wafer according to claim 22, characterized in that: The material of the second dielectric layer includes silicon nitride.

24. The semiconductor wafer according to claim 22, characterized in that: The thickness of the second dielectric layer is 100-500 nm.

25. The semiconductor wafer according to claim 22, characterized in that: The second metal adhesion layer is made of titanium.

26. The semiconductor wafer according to claim 22, characterized in that: The thickness of the second metal adhesion layer is 10-50 nm.

27. The semiconductor wafer according to claim 22, characterized in that: The material of the second diffusion barrier layer includes platinum, and the thickness of the second diffusion barrier layer is 10-50 nm.

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