A method for direct wafer bonding using thin film deposition to compensate for deformation

Abstract

The present invention belongs to the field of microelectronic device packaging technology, and specifically discloses a method for direct wafer bonding using thin film deposition to compensate for deformation, comprising: obtaining a first initial warp of a first wafer and a second initial warp of a second wafer, applying stress to the first wafer and the second wafer respectively, causing the first wafer to deform and adjust to compensate for the first initial warp, and the second wafer to deform and adjust to compensate for the second initial warp; performing surface activation on the first and second wafers after deformation adjustment, and bonding them at room temperature and a pressure of 1000mbar to 6000mbar to obtain a bonding structure; the method for applying stress is to deposit a silicon dioxide film, and by adjusting the density and thickness of the silicon dioxide film, the direction and magnitude of the stress can be controlled. The present invention compensates for the deformation of the wafers to be bonded by depositing a silicon dioxide film and performs surface activation treatment, thereby achieving direct wafer bonding at room temperature and normal pressure.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing and microelectronic device packaging, and more specifically, relates to a method for directly bonding wafers by utilizing thin film deposition to compensate for deformation. Background Art

[0002] With the increasing demand for high integration, high performance and miniaturization, the preparation process of high-voltage silicon carbide devices of 10kV and above requires a thin-film process that removes the substrate. The existing process cannot support thin films. The bonding process uses a technology that bonds the thinned epitaxial wafer to the supporting silicon carbide wafer. The traditional process can be used to achieve thin-film processing of high-voltage silicon carbide devices and improve the device preparation rate.

[0003] Wafer bonding technology refers to the process of directly bonding two polished wafers with clean, flat and smooth surfaces together based on intermolecular forces or chemical bonds. It is a glue-free bonding technology that does not use adhesives. The lower layer of SiC material serves as the support layer, and the upper layer of SiC material serves as the device layer. Direct connection between materials can be achieved without the introduction of an intermediate layer, and there is no problem of impurity introduction. In addition, SiC wafer bonding technology can overcome the problems of uneven thick film epitaxial deposition and epitaxial lattice mismatch, reduce the risk of fragmentation during the device manufacturing process, and greatly reduce chip manufacturing costs.

[0004] Chinese patent document CN109904064A discloses a method for improving the direct bonding strength of silicon carbide, which requires treatment with hydrofluoric acid and heating to 1100°C to 1300°C. Chinese patent document CN106449379A discloses a method for directly bonding silicon to silicon or silicon carbide to silicon carbide. This method does not require the use of hydrofluoric acid, but requires bonding within a temperature range of greater than or equal to 1335°C and less than 1414°C. These bonding processes require high temperatures and / or acidic bonding environments, making it difficult to directly bond SiC wafers without an intermediate layer at room temperature and pressure. Summary of the Invention

[0005] In response to the defects of the prior art, the purpose of the present invention is to provide a method for direct wafer bonding using thin film deposition to compensate for deformation, aiming to solve the problem that the existing direct wafer bonding process that does not require an intermediate layer needs to be carried out under harsh conditions such as high temperature, high pressure or acidity.

[0006] To achieve the above object, the present invention provides a method for direct wafer bonding using thin film deposition to compensate for deformation, comprising the following steps:

[0007] Obtaining a first initial warpage of a first wafer, and applying stress to the first wafer so that the first wafer is deformed and adjusted to compensate for the first initial warpage;

[0008] Obtaining a second initial warpage of the second wafer, and applying stress to the second wafer so that the second wafer is deformed and adjusted to compensate for the second initial warpage;

[0009] Activating the surfaces of the deformed first wafer and the deformed second wafer, and bonding them at room temperature and a pressure of 1000 mbar to 6000 mbar to obtain a bonding structure;

[0010] The method of applying stress is to deposit a silicon dioxide film. By adjusting the density and thickness of the silicon dioxide film, the direction and magnitude of the applied stress can be controlled.

[0011] Preferably, the first wafer and the second wafer are silicon carbide substrates, silicon carbide epitaxy or silicon.

[0012] Preferably, the method of the present invention further comprises adjusting the thickness of the silicon dioxide film according to a film thickness-deformation model to control the magnitude of the applied stress, thereby regulating the warpage of the wafer to be bonded after the deformation adjustment, wherein the wafer to be bonded is the first wafer or the second wafer, and the film thickness-deformation model is shown in Formula 1:

[0013]

[0014] Wherein, A1 is the initial warpage of the wafer to be bonded, B1 is the thickness of the wafer to be bonded, E1 is the Young's modulus of the wafer to be bonded, α1 is the thermal expansion coefficient of the wafer to be bonded, A2 is the warpage of the structure after deposition, B2 is the thickness of the silicon dioxide film, E2 is the Young's modulus of the silicon dioxide film, α2 is the thermal expansion coefficient of the silicon dioxide film, ΔT is the difference between the deposition temperature and room temperature, c is the uniform strain component, C2 is the neutral plane position, and the calculation formula of the neutral plane position is shown in Formula II:

[0015]

[0016] Further preferably, the method for obtaining the Young's modulus E2 and the thermal expansion coefficient α2 of the silicon dioxide film is as follows:

[0017] Silicon dioxide films of different thicknesses were deposited on silicon wafers of the same thickness, and the warpage of the initial and post-deposition silicon wafers was tested to obtain the corresponding strain information.

[0018] Depositing silicon dioxide films of the same thickness on silicon wafers of different thicknesses, respectively, and measuring the thickness of the deposited silicon dioxide films using an ellipsometer to ensure the consistency of the thickness of the silicon dioxide films, and measuring the warpage of the initial silicon wafer and the silicon wafer after deposition to obtain corresponding strain information;

[0019] Substituting the obtained multiple sets of strain information into formula I, the Young's modulus E2 and thermal expansion coefficient α2 of the deposited silicon dioxide film are calculated;

[0020] The strain information includes the thickness B1 of the silicon wafer, the initial warpage A1, the thickness B2 of the silicon dioxide film, and the warpage A2 of the silicon wafer after deposition.

[0021] Preferably, the warping of the first wafer after deformation adjustment and the warping of the second wafer after deformation adjustment are both less than 10 μm.

[0022] Preferably, when the initial warping direction of the wafer to be bonded is from the bonding surface to the non-bonding surface, compressive stress is applied to the non-bonding surface of the wafer to be bonded; when the initial warping direction of the wafer to be bonded is from the non-bonding surface to the bonding surface, tensile stress is applied to the non-bonding surface of the wafer to be bonded; wherein, the wafer to be bonded is the first wafer or the second wafer.

[0023] Further preferably, the method of applying compressive stress is to deposit a dense silicon dioxide film using a plasma enhanced chemical vapor deposition process, and the process parameters during the deposition process are: deposition power is 10W to 30W, silane and nitrous oxide are used as reaction gases, the flow rate of silane is 80sccm to 120sccm, and the flow rate of nitrous oxide is 700sccm to 720sccm.

[0024] Further preferably, the method of applying tensile stress is to deposit an ordinary silicon dioxide film using a plasma enhanced chemical vapor deposition process, and the process parameters during the deposition process are: deposition power is 10W to 30W, silane and nitrous oxide are used as reaction gases, the flow rate of silane is 440sccm to 460sccm, and the flow rate of nitrous oxide is 730sccm to 760sccm.

[0025] Preferably, the surface activation process is as follows: the first wafer after deformation adjustment and the second wafer after deformation adjustment are activated by oxygen ion and argon particle flow, the oxygen flow rate is 40sccm~150sccm, the argon flow rate is 0~120sccm, the activation power is 30W~300W, and the activation time is 10s~600s.

[0026] Preferably, after bonding, the bonding structure is further annealed. The annealing process is as follows: the annealing temperature is 200° C. to 300° C., and the annealing time is 60 min to 300 min.

[0027] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0028] (1) The present invention applies stress in the opposite direction of the initial deformation to the wafer to compensate for deformation by depositing a thin film on the back of the wafer device to be bonded, and activates the wafer surface, thereby achieving direct wafer bonding at room temperature and low pressure, effectively avoiding affecting the performance of the device on the wafer; at the same time, by adjusting the density and thickness of the deposited silicon dioxide film, the direction and magnitude of the applied stress can be adjusted and controlled.

[0029] (2) When bonding silicon carbide wafers, the present invention does not require direct experiments on expensive silicon carbide wafers to obtain the relationship between the thickness and deformation of the deposited material. Instead, the relationship between the thickness and deformation of the deposited material is obtained based on the deformation changes caused by deposition on the silicon substrate, and the deformation caused by deposition on the silicon carbide substrate is then calculated. This reduces costs while ensuring the reliability of direct bonding.

[0030] (3) The wafer direct bonding method provided by the present invention is simple and easy to operate, does not require harsh reaction conditions, and can achieve precise control of bonding, and is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the initial deformation of a silicon carbide substrate and a silicon carbide epitaxial layer to be bonded provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the deformation change of a silicon carbide substrate to be bonded before and after the deposition of a silicon dioxide film provided in an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the deformation change of the silicon carbide epitaxial layer to be bonded before and after the deposition of the silicon dioxide film provided in an embodiment of the present invention;

[0034] Figure 4 Schematic diagram of bonding between a silicon carbide substrate and a silicon carbide epitaxial layer after deformation compensation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The present invention provides a method for direct wafer bonding using thin film deposition to compensate for deformation, comprising the following steps:

[0037] Obtaining a first initial warpage of a first wafer, and applying stress to the first wafer so that the first wafer is deformed and adjusted to compensate for the first initial warpage;

[0038] Obtaining a second initial warpage of the second wafer, and applying stress to the second wafer so that the second wafer is deformed and adjusted to compensate for the second initial warpage;

[0039] Activating the surfaces of the deformed first wafer and the deformed second wafer, and bonding them at room temperature and a pressure of 1000 mbar to 6000 mbar to obtain a bonding structure;

[0040] The method of applying stress is to deposit a silicon dioxide film. By adjusting the density and thickness of the silicon dioxide film, the direction and magnitude of the applied stress can be controlled.

[0041] This method applies stress in the opposite direction of the initial deformation to the wafers being bonded by depositing a thin film to compensate for deformation. Furthermore, the wafer surface is activated, enabling direct wafer bonding at room temperature and low pressure, effectively avoiding any impact on the performance of devices on the wafers. Furthermore, by adjusting the density and thickness of the deposited silicon dioxide film, the direction and magnitude of the applied stress can be adjusted and controlled.

[0042] In some embodiments, the first wafer and the second wafer are high-purity silicon carbide or silicon. It should be understood that the first wafer and the second wafer to be bonded here can be either substrates or epitaxy.

[0043] The stress of the film consists of two parts: thermal stress and intrinsic stress. Thermal stress originates from the difference in thermal expansion coefficient between the film and the substrate, and the warping of the substrate and the silicon dioxide layer structure must meet the boundary conditions of the force equilibrium state. Based on this theory, the present invention derives a film thickness-deformation model, as shown in Formula I. The method for direct bonding of wafers in an embodiment of the present invention also includes adjusting the thickness of the silicon dioxide film according to the film thickness-deformation model to control the magnitude of the applied stress, thereby regulating the warping of the wafer to be bonded after deformation adjustment, wherein the wafer to be bonded is the first wafer or the second wafer, and the film thickness-deformation model:

[0044]

[0045] Wherein, A1 is the initial warpage of the wafer to be bonded, B1 is the thickness of the wafer to be bonded, E1 is the Young's modulus of the wafer to be bonded, α1 is the thermal expansion coefficient of the wafer to be bonded, A2 is the warpage of the structure after deposition, B2 is the thickness of the silicon dioxide film, E2 is the Young's modulus of the silicon dioxide film, α2 is the thermal expansion coefficient of the silicon dioxide film, ΔT is the difference between the deposition temperature and room temperature, c is the uniform strain component, C2 is the neutral plane (the plane where the bending strain is zero) position, and the calculation formula of the neutral plane position is shown in Formula II:

[0046]

[0047] Furthermore, the Young's modulus E2 and thermal expansion coefficient α2 of the silicon dioxide film are obtained as follows:

[0048] Silicon dioxide films of different thicknesses were deposited on silicon wafers of the same thickness, and the warpage of the initial and post-deposition silicon wafers was tested to obtain the corresponding strain information.

[0049] Depositing silicon dioxide films of the same thickness on silicon wafers of different thicknesses, respectively, and measuring the thickness of the deposited silicon dioxide films using an ellipsometer to ensure the consistency of the thickness of the silicon dioxide films, and measuring the warpage of the initial silicon wafer and the silicon wafer after deposition to obtain corresponding strain information;

[0050] Substituting the obtained multiple sets of strain information into formula I, the Young's modulus E2 and thermal expansion coefficient α2 of the deposited silicon dioxide film are calculated;

[0051] The strain information includes the thickness B1 of the silicon wafer, the initial warpage A1, the thickness B2 of the silicon dioxide film, and the warpage A2 of the silicon wafer after deposition.

[0052] The present invention proposes that the deposition and deformation of a silicon carbide substrate can be calculated based on the deposition and deformation of a silicon substrate, thereby realizing the calculation of bonding of expensive wafers under relatively low-cost experimental conditions.

[0053] In some embodiments, in order to ensure the effect of hydrophilic bonding, the warpage of the first wafer after the deformation adjustment and the second wafer after the deformation adjustment are both less than 10 μm.

[0054] In some embodiments, when the initial warpage direction of the wafers to be bonded is from the bonding surface to the non-bonding surface, compressive stress is applied to the non-bonding surface of the wafers to be bonded; and when the initial warpage direction of the wafers to be bonded is from the non-bonding surface to the bonding surface, tensile stress is applied to the non-bonding surface of the wafers to be bonded. The wafers to be bonded are the first wafer or the second wafer. Those skilled in the art should understand that the bonding surface is the side of the wafer to be bonded on which devices are fabricated, and the non-bonding surface is the side facing away from the bonding surface.

[0055] The present invention uses a large number of stress tests to determine the relationship between the direction of stress generation and the density of the deposited silicon dioxide film. The stress testing method can adopt the cantilever beam method, Newton ring method, etc. Specifically, the method of applying compressive stress is to deposit a dense silicon dioxide film using a plasma-enhanced chemical vapor deposition (PEVCD) process. The process parameters during the deposition process are: deposition power of 10W to 30W, silane and nitrous oxide as the reaction gases, silane flow rate of 80sccm to 120sccm, and nitrous oxide flow rate of 700sccm to 720sccm.

[0056] Specifically, the method of applying tensile stress is to deposit an ordinary silicon dioxide film using a PEVCD process, and the process parameters during the deposition process are: deposition power is 10W to 30W, silane and nitrous oxide are used as reaction gases, the silane flow rate is 440sccm to 460sccm, and the nitrous oxide flow rate is 730sccm to 760sccm.

[0057] In some embodiments, the surface activation process is as follows: the first wafer after deformation adjustment and the second wafer after deformation adjustment are activated with oxygen ion and argon particle flow, with an oxygen flow rate of 40 sccm to 150 sccm, an argon flow rate of 0 to 120 sccm, an activation power of 30 W to 300 W, and an activation time of 10 seconds to 600 seconds. The activation treatment of the wafers to be bonded forms hydroxide ions on the wafer surface, which not only makes the wafer surface hydrophilic but also prevents the adsorption of impurity particles in the environment on the surface due to van der Waals forces.

[0058] It should be noted that the optimized conditions for the surface activation treatment provided by the present invention are obtained by verifying the contact angle test after multiple activations. The specific method is as follows: using a contact angle tester, the same batch of silicon wafers are tested to obtain the initial contact angle, and the silicon wafers are activated by oxygen ion and argon particle flow in the RIE equipment; the silicon wafers are activated under the oxygen ion flow with the same processing power and different processing times, and tested after activation to obtain the contact angle after activation and the processing time corresponding to the maximum contact angle; the silicon wafers are activated under the oxygen ion flow with the same processing time and different processing powers, and tested after activation to obtain the contact angle after activation and the processing power corresponding to the maximum contact angle.

[0059] In some embodiments, in order to make the wafer bonding stronger, after bonding, the bonding structure is further annealed. The annealing process is as follows: the annealing temperature is 200° C. to 300° C., and the annealing time is 60 min to 300 min.

[0060] The above technical solution is described in detail below in conjunction with specific embodiments.

[0061] The technical solution of the present invention is described below by taking the direct bonding of a pair of silicon carbide substrates 10 and silicon carbide epitaxy 20 as an example.

[0062] The initial warpage A of the silicon carbide substrate 10 to be bonded is measured by a thin film stress tester. 11 , thickness B 11 and the initial warpage A of the silicon carbide epitaxial 20 12 , thickness B 12 ,like Figure 1 As shown, in this embodiment, tensile stress needs to be applied to the silicon carbide substrate 10 and the silicon carbide epitaxy 20 to compensate for deformation.

[0063] The tensile stress was applied by depositing a conventional silicon dioxide film using a plasma-enhanced chemical vapor deposition (PECVD) process. The deposition parameters were: a deposition power of 20 W, silane and nitrous oxide as the reactant gases, with a silane flow rate of 450 sccm and a nitrous oxide flow rate of 750 sccm. This process was used for the deposition of silicon dioxide films in the following examples.

[0064] Based on the film thickness-deformation model:

[0065]

[0066]

[0067] Among them, A1 is the initial warpage of the wafer to be bonded, B1 is the thickness of the wafer to be bonded, E1 is the Young's modulus of the wafer to be bonded, α1 is the thermal expansion coefficient of the wafer to be bonded, A2 is the warpage of the structure after deposition, B2 is the thickness of the deposited silicon dioxide film, E2 is the Young's modulus of the silicon dioxide film, α2 is the thermal expansion coefficient of the silicon dioxide film, ΔT is the difference between the deposition temperature and room temperature, c is the uniform strain component, and C2 is the neutral plane position.

[0068] Silicon dioxide films of varying thicknesses were deposited on silicon wafers of the same thickness using different processing times. The warpage of the deposited wafers was then measured to obtain several sets of required strain information (silicon wafer thickness B1, initial warpage A1, silicon dioxide film thickness B2, and warpage A2 of the deposited wafer). Silicon dioxide films of the same thickness were deposited on silicon wafers of varying thicknesses. Ellipsometer testing was performed on the deposited films to ensure thickness consistency. The warpage of the deposited wafers was then measured to obtain further sets of required strain information (silicon wafer thickness B1, initial warpage A1, silicon dioxide film thickness B2, and warpage A2 of the deposited wafer). This strain information, along with the difference ΔT between the deposition temperature and room temperature, was substituted into the multivariate equations of the aforementioned model to obtain the material properties of the deposited silicon dioxide films (Young's modulus E2 and thermal expansion coefficient α2), and the corresponding values of c and C2 were determined.

[0069] The parameters of the deposited silicon dioxide film (Young's modulus E2 and thermal expansion coefficient α2) and the parameters of the selected silicon carbide substrate 10 (initial warpage A 11 and thickness B 11 ), substitute it into the model, and the warpage A of the deposited silicon carbide substrate 10 21 If the thickness B of the lower silicon dioxide film 30 required to be deposited to compensate for the initial deformation of the selected silicon carbide substrate 10 is controlled within 10 μm, the thickness B of the lower silicon dioxide film 30 can be calculated. 21 ,like Figure 2 The parameters of the deposited silicon dioxide film (Young's modulus E2 and thermal expansion coefficient α2) and the parameters of the selected silicon carbide epitaxial 20 (initial warpage A 12 and thickness B 12 ), substitute it into the model, and the warpage A of the deposited silicon carbide epitaxial 20 22 If the thickness B of the upper silicon dioxide film 40 required to compensate for the initial deformation of the selected silicon carbide epitaxial layer 20 is controlled within 10 μm, the thickness B of the upper silicon dioxide film 40 can be calculated. 22 ,like Figure 3 shown.

[0070] After PECVD coating, the two SiC wafers were first oxygen-cleaned using alpha, then activated with oxygen ions and argon particles in a RIE device. Activation conditions were: an oxygen flow rate of 100 sccm, an argon flow rate of 60 sccm, an activation power of 100W, and an activation time of 180 seconds. After activation, water shock was applied in a yellow light chamber, and the surface water was blown dry. The two SiC wafers were then directly bonded at room temperature under a pressure of 4000 mbar. Finally, a 300°C annealing treatment was performed in an incubator for 3 hours to complete the bonding. Figure 4 shown.

[0071] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for direct wafer bonding using thin film deposition to compensate for deformation, characterized in that: The steps include: Obtaining a first initial warpage of a first wafer, and applying stress to the first wafer so that the first wafer is deformed and adjusted to compensate for the first initial warpage; Obtaining a second initial warpage of the second wafer, and applying stress to the second wafer so that the second wafer is deformed and adjusted to compensate for the second initial warpage; Activating the surfaces of the deformed first wafer and the deformed second wafer, and bonding them at room temperature and a pressure of 1000 mbar to 6000 mbar to obtain a bonded structure, wherein the surface activation method is oxygen ion and argon particle flow activation; The method of applying stress is to deposit a silicon dioxide film. By adjusting the density and thickness of the silicon dioxide film, the direction and magnitude of the applied stress can be controlled. According to the film thickness-deformation model, the thickness of the silicon dioxide film is adjusted to control the magnitude of the applied stress, thereby regulating the warpage of the wafer to be bonded after deformation adjustment, wherein the wafer to be bonded is the first wafer or the second wafer, and the film thickness-deformation model is shown in Formula 1: I Wherein, A1 is the initial warpage of the wafer to be bonded, B1 is the thickness of the wafer to be bonded, E1 is the Young's modulus of the wafer to be bonded, α1 is the thermal expansion coefficient of the wafer to be bonded, A2 is the warpage of the structure after deposition, B2 is the thickness of the silicon dioxide film, E2 is the Young's modulus of the silicon dioxide film, α2 is the thermal expansion coefficient of the silicon dioxide film, ∆T is the difference between the deposition temperature and room temperature, c is the uniform strain component, C2 is the neutral plane position, and the calculation formula of the neutral plane position is shown in Formula II: II。 2. The method according to claim 1, wherein: The first wafer and the second wafer are silicon carbide substrates, silicon carbide epitaxy or silicon.

3. The method according to claim 1, characterized in that The Young's modulus E2 and thermal expansion coefficient α2 of the silicon dioxide film are obtained as follows: Silicon dioxide films of different thicknesses were deposited on silicon wafers of the same thickness, and the warpage of the initial and post-deposition silicon wafers was tested to obtain the corresponding strain information. Depositing silicon dioxide films of the same thickness on silicon wafers of different thicknesses, respectively, and measuring the thickness of the deposited silicon dioxide films using an ellipsometer to ensure the consistency of the thickness of the silicon dioxide films, and measuring the warpage of the initial silicon wafer and the silicon wafer after deposition to obtain corresponding strain information; Substituting the obtained multiple sets of strain information into formula I, the Young's modulus E2 and thermal expansion coefficient α2 of the deposited silicon dioxide film are calculated; The strain information includes the thickness B1 of the silicon wafer, the initial warpage A1, the thickness B2 of the silicon dioxide film, and the warpage A2 of the silicon wafer after deposition.

4. The method according to claim 1, wherein: The warpage of the first wafer after deformation adjustment and the warpage of the second wafer after deformation adjustment are both less than 10 μm.

5. The method according to claim 1, wherein: When the initial warping direction of the wafer to be bonded points from the bonding surface to the non-bonding surface, compressive stress is applied to the non-bonding surface of the wafer to be bonded; when the initial warping direction of the wafer to be bonded points from the non-bonding surface to the bonding surface, tensile stress is applied to the non-bonding surface of the wafer to be bonded; wherein, the wafer to be bonded is the first wafer or the second wafer.

6. The method according to claim 5, wherein The method for applying compressive stress is to deposit a dense silicon dioxide film using a plasma-enhanced chemical vapor deposition process. The process parameters during the deposition process are: deposition power is 10W~30W, silane and nitrous oxide are used as reaction gases, the silane flow rate is 80 sccm~120 sccm, and the nitrous oxide flow rate is 700 sccm~720 sccm.

7. The method according to claim 5, wherein The method for applying tensile stress is to deposit an ordinary silicon dioxide film using a plasma-enhanced chemical vapor deposition process. The process parameters during the deposition process are: a deposition power of 10W to 30W, silane and nitrous oxide as reaction gases, a silane flow rate of 440 sccm to 460 sccm, and a nitrous oxide flow rate of 730 sccm to 760 sccm.

8. The method according to claim 1, wherein The parameters of the oxygen ion and argon particle flow activation are: oxygen flow rate of 40 sccm~150 sccm, argon flow rate of 0~120 sccm, activation power of 30 W~300 W, and activation time of 10 s~600 s.

9. The method according to any one of claims 1 to 8, wherein After bonding, the bonding structure is annealed. The annealing process is as follows: the annealing temperature is 200° C. to 300° C., and the annealing time is 60 min to 300 min.

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