A method for temporary bonding and debonding, a method for preparing a composite substrate, and a method for manufacturing a wafer

Abstract

The present invention belongs to the field of semiconductor processing and manufacturing. The present invention provides a method for temporary bonding and debonding, a method for preparing a composite substrate, and a method for manufacturing a wafer. The method for temporary bonding and debonding includes forming a silicon oxide layer on two silicon substrates, performing ion implantation, hydrofluoric acid treatment, and plasma activation on the silicon oxide layer, achieving temporary bonding of the two silicon substrates through hydrophilic bonding, and then performing debonding annealing to cause the temporary bonding interface to crack and achieve debonding. This method does not require the use of a bonding medium, and can maintain the same thermal properties of the two substrates, effectively avoiding warping and breaking; the strength of the temporary bonding is high and the stability is good. Using this method, a significant thinning of the functional substrate can be achieved, thereby preparing a composite substrate or further used for manufacturing a multi-layer wafer bonding structure.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor processing and manufacturing, and relates to a method for temporary bonding and debonding, a method for preparing a composite substrate, and a method for manufacturing a wafer. Background Art

[0002] Temporary bonding is a key technology in semiconductor manufacturing and advanced packaging processes, mainly used to solve the "holding" and "supporting" problems during the processing of ultra-thin wafers. The implementation of this technology usually requires a relatively thick support substrate for support and a relatively thin functional substrate supported (held) by it. By temporarily bonding the functional substrate to the support substrate, the strength of the functional substrate can be enhanced to ensure that it is not damaged during subsequent process steps (such as thinning). At the end of the process, the support substrate is removed, and this removal process is called debonding.

[0003] The existing methods for temporary bonding and debonding mainly include the following:

[0004] First, thermocompression bonding. In this method, the support substrate and the functional substrate are heated to a specific temperature, and the two are bonded together by applying a certain pressure. A bonding medium (usually glue) is coated at the temporary bonding interface. During debonding, the bonding medium is softened by heating and loses its adhesion, so that the support substrate and the functional substrate are separated.

[0005] Second, thermal slip debonding. This method also uses a bonding medium to adhere the support substrate and the functional substrate together. During debonding, the bonding medium is first softened by heating to lose its adhesion, and then a slip force in the opposite direction is applied to the support substrate and the functional substrate to promote their separation.

[0006] Third, laser debonding. It still adheres the support substrate and the functional substrate through a bonding medium first. During debonding, the bonding medium layer is ablated by laser to make it softened and lose its adhesion ability, realizing the separation of the support substrate and the functional substrate.

[0007] In summary, in the existing temporary bonding methods, a bonding medium for adhesion, generally a bonding glue, is provided on the temporary bonding surface between the support substrate and the functional substrate.

[0008] However, the bonding glue has the following problems in temporary bonding:

[0009] First, poor thermal stability. The bonding glue generally has a maximum heat resistance of about 300 °C, and this limitation makes it impossible for the functional substrate to perform process steps with high temperatures.

[0010] Second, the thickness of the existing process bonding adhesive layer is generally about 100 μm. It is often spin-coated on the surface of the substrate by spin coating process, and it is difficult to form an atomically flat adhesive surface on the substrate surface, resulting in poor parallelism of the functional substrate relative to the support substrate, and the rigidity of the bonding adhesive layer is poor, ultimately resulting in poor support strength for the functional substrate. These problems lead to the inability to effectively thin the functional substrate to the extreme, bringing difficulties to obtaining an ultra-thin functional substrate, thus unable to reduce the thickness of the subsequent fabricated device. At the same time, the inability to reduce the thickness will also affect the performance of the device. For example, it will increase the length of the conductive medium between the stacked layers, thereby affecting the heat dissipation and working efficiency of the device.

[0011] Third, the decomposition and volatilization of the bonding adhesive will introduce impurities on the surface of the functional substrate, and the remaining adhesive also needs additional processes to be cleaned and removed, increasing the cost and the complexity of the process.

[0012] Regarding the above problems, in the existing technology, to avoid the adverse factors brought by the bonding adhesive, there is also research on using metal as the bonding medium to achieve temporary bonding. Correspondingly, when debonding, it is necessary to ablate the metal medium by laser passing through the support substrate. Although this technology can perform high-temperature process manufacturing on the functional substrate due to the high temperature resistance of the metal, there are still the following problems:

[0013] When using laser debonding, to prevent laser damage to the functional substrate, the laser needs to pass through the support substrate from the support substrate side and then be focused on the bonding medium layer to ablate the metal bonding medium layer. To enable the laser to pass through the support substrate and be effectively focused on the bonding medium layer, glass with high light transmittance is often selected as the support substrate. And the functional substrate is generally a silicon substrate. When the glass-based support substrate and the silicon-based functional substrate are temporarily bonded and then subjected to high-temperature process manufacturing, due to the difference in the thermal expansion coefficients of the materials, a large stress will be introduced, causing the thinner functional substrate to warp or break. If silicon material is used as the support substrate, although it can avoid the adverse factors caused by the difference in thermal expansion coefficients, the light transmittance of the laser is low, and the metal medium layer cannot be effectively ablated, thus resulting in the failure of debonding.

[0014] From the above, it can be seen that there is currently a lack of a solution that can avoid the influence of the bonding medium and even effectively achieve temporary bonding and debonding without using the bonding medium. Summary of the Invention

[0015] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for temporary bonding and debonding, a method for preparing a composite substrate, and a method for manufacturing a wafer. The method for temporary bonding and debonding includes forming a silicon oxide layer on two silicon substrates, performing ion implantation, hydrofluoric acid treatment, and plasma activation on the silicon oxide layer, achieving temporary bonding of the two silicon substrates through hydrophilic bonding, and then performing debonding annealing to cause the temporary bonding interface to crack and achieve debonding. This method does not require the use of a bonding medium, and can maintain the same thermal performance of the two substrates, effectively avoiding warping and breaking; the strength of the temporary bonding is high and the stability is good, and it can withstand and adapt to other processing technologies that require high-temperature treatment at 350~1250°C. Using this method, the functional substrate can be greatly thinned, so as to prepare a composite substrate or further used for manufacturing a multi-layer wafer bonding structure.

[0016] To achieve this purpose, the present invention adopts the following technical solutions:

[0017] In the first aspect, the present invention provides a method for temporary bonding and debonding, including the following steps:

[0018] A1. Provide two silicon substrates, and form a silicon oxide layer on one side of the silicon substrates;

[0019] A2. Perform ion implantation, hydrofluoric acid treatment, and plasma activation on the silicon oxide layer in sequence to form a temporary bonding surface;

[0020] A3. Bring the temporary bonding surfaces into contact, perform hydrophilic bonding, and then perform strengthening annealing to form a temporary bond between the two silicon substrates and complete the temporary bonding;

[0021] A4. Perform debonding annealing on the temporary bond to cause the silicon oxide layers of the two silicon substrates to separate at the temporary bonding interface and complete the debonding.

[0022] In the method for temporary bonding and debonding of the present invention, the two substrates used for temporary bonding (referred to as the support substrate and the functional substrate respectively) are selected as silicon substrates. Being made of silicon can effectively avoid warping or breaking problems caused by differences in thermal expansion coefficients. The support substrate and the functional substrate made of silicon have high consistency in thermal performance, and the degree of thermal expansion and contraction under various temperature conditions is relatively close, thus greatly reducing the risk of damage to the bonding structure due to different thermal expansion coefficients.

[0023] The principle of the present invention for achieving temporary bonding and debonding includes that through plasma activation, sufficient dangling hydroxyl groups and active sites are generated on the surface (temporary bonding surface) of the silicon oxide layer, so as to achieve hydrophilic bonding using two activated silicon oxide layers, and further enhance the bonding strength through strengthening annealing (>2 J / m 2), to ensure the strength and stability of the temporary bonding. Before the hydrophilic bonding, the present invention performs ion implantation and hydrofluoric acid treatment on the silicon oxide layer. Ion implantation forms an ion implantation layer inside the silicon oxide layer. Subsequently, through hydrofluoric acid treatment, the hydrofluoric acid component reacts with the silicon oxide layer to break the ring structure formed by silicon-oxygen bonds, creating channels in the oxide layer that allow ion elements to flow through. Through the high-temperature treatment of debonding annealing, it promotes the movement of ion elements between the lattices of the silicon oxide layer and precipitates from the channels at the temporary bonding interface, thereby causing the temporary bonding interface to crack, and the two silicon oxide layers of the temporary bonding to crack and separate, achieving debonding.

[0024] It can be seen that in the method of temporary bonding and debonding described in the present invention, no bonding medium needs to be introduced at the temporary bonding interface between the support substrate and the functional substrate. The advantages of this design are as follows. First, it can avoid the problem of limited high-temperature processes caused by the bonding medium. For example, in some cases, the bonding medium may soften in a high-temperature environment, thus affecting the reliability of the entire temporary bonding structure. Second, due to the absence of the traditional coated organic chemical bonding medium, the flatness, temperature tolerance, and strength of the temporary bonding surface are greatly improved, and the subsequent processing of the functional substrate is easy to operate and control. For example, it can greatly reduce the difficulty of thinning the functional substrate and achieve the manufacture of an ultra-thin functional substrate. Third, it can avoid the impurity contamination and cleaning problems brought about by the use of the bonding medium. The bonding medium may introduce impurities, which not only affect the bonding quality but may also have an adverse impact on the product performance in subsequent processes, and removing these impurities also requires additional time and resources.

[0025] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0026] As a preferred technical solution of the present invention, in step A1, the method of forming the silicon oxide layer includes thermal oxidation.

[0027] Preferably, the thickness of the silicon oxide layer is 1 to 1000 nm, such as 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 25 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1000 nm, etc.

[0028] As a preferred technical solution of the present invention, in step A2, before the ion implantation, the surface of the silicon oxide layer is first planarized to make the surface roughness ≤ 1 nm, such as 1 nm, 0.95 nm, 0.9 nm, 0.85 nm, 0.8 nm, 0.75 nm, 0.7 nm, 0.65 nm, 0.6 nm, 0.55 nm, 0.5 nm, 0.45 nm, 0.4 nm, 0.35 nm, 0.3 nm, 0.25 nm, 0.2 nm, 0.15 nm, 0.1 nm or 0.05 nm, etc.

[0029] Preferably, in step A2, the ion element for the ion implantation includes hydrogen ions.

[0030] The ion element for the ion implantation in the present invention is preferably hydrogen ions. When debonding annealing is carried out, hydrogen atoms move between the lattices of the silicon oxide layer, flow through the channels formed by the hydrofluoric acid treatment and precipitate onto the temporary bonding interface, form hydrogen gas by recombination and form uniformly distributed bubbles on the temporary bonding interface, so that the temporary bonding interface cracks and the debonding is completed.

[0031] Preferably, the implantation energy of the ion implantation is 1 - 80 keV, such as 1 keV, 3 keV, 5 keV, 8 keV, 10 keV, 15 keV, 20 keV, 25 keV, 30 keV, 35 keV, 40 keV, 45 keV, 50 keV, 55 keV, 60 keV, 65 keV, 70 keV, 75 keV or 80 keV, etc.; the implantation dose is 1×10 13 ~8×10 16 ions / cm 2 ,such as 1×10 13 ions / cm 2 、3×10 13 ions / cm 2 、5×10 13 ions / cm 2 、8×10 13 ions / cm 2 、1×10 14 ions / cm 2 、3×10 14 ions / cm 2 、5×10 14 ions / cm 2 、8×10 14 ions / cm 2 、1×10 15 ions / cm 2 、3×10 15 ions / cm 2 、5×10 15ions / cm 2 , 8×10 15 ions / cm 2 , 1×10 16 ions / cm 2 , 3×10 16 ions / cm 2 , 5×10 16 ions / cm 2 or 8×10 16 ions / cm 2 etc.; The implantation depth is 0.1~1000nm, such as 0.1nm, 0.3nm, 0.5nm, 0.8nm, 1nm, 3nm, 5nm, 8nm, 10nm, 25nm, 50nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm etc.

[0032] It should be noted that in order to ensure that the silicon substrate is not damaged by ion implantation, it is preferably that the depth of the ion implantation is less than the thickness of the silicon oxide layer.

[0033] Preferably, after the ion implantation and before the hydrofluoric acid treatment, the silicon substrate is first cleaned to remove surface impurities; The method of the first cleaning includes first performing a tank cleaning with a mixed solution of ammonia water, hydrogen peroxide and deionized water, and then performing a tank cleaning with a mixed solution of hydrochloric acid, hydrogen peroxide and deionized water.

[0034] As a preferred technical solution of the present invention, in step A2, the method of the hydrofluoric acid treatment includes soaking in a hydrofluoric acid solution, and the mass percentage concentration of the hydrofluoric acid solution is 0.1%~30%, such as 0.1%, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28% or 30% etc.

[0035] Preferably, the temperature of the hydrofluoric acid treatment is 10~50°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C etc., and the time is 1~100s, such as 1s, 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, 70s, 75s, 80s, 85s, 90s, 95s or 100s etc.

[0036] Preferably, after the hydrofluoric acid treatment and before the plasma activation, the silicon substrate is cleaned and spin-dried to remove the surface residual solution after the second cleaning; The method of the second cleaning includes cleaning with deionized water.

[0037] In the present invention, the purpose of hydrofluoric acid treatment is to form channels for the flow of ion-implanted elements. If the treatment degree is too large, it will cause the surface roughness to increase due to corrosion. During temporary bonding, voids are likely to exist at the temporary bonding interface, resulting in a decrease in the temporary bonding strength and even lattice damage in the silicon substrate. Therefore, the concentration of the hydrofluoric acid solution used in the hydrofluoric acid treatment, as well as the temperature and time of the hydrofluoric acid treatment, should be reasonably adjusted and selected.

[0038] As a preferred technical solution of the present invention, in step A2, the gas for generating plasma in the plasma activation includes at least one of N 2 , O 2 , Ar or He.

[0039] Preferably, after the plasma activation and before the hydrophilic bonding, the silicon substrate is subjected to a third cleaning to remove surface particles.

[0040] As a preferred technical solution of the present invention, in step A3, the method of hydrophilic bonding includes a center point pressing method or a planar pressing method.

[0041] Preferably, the pressing pressure for the hydrophilic bonding is 1 - 1000 N, such as 1 N, 5 N, 8 N, 10 N, 30 N, 50 N, 80 N, 100 N, 200 N, 300 N, 400 N, 500 N, 600 N, 700 N, 800 N, 900 N or 1000 N, etc., and the pressing holding time is 1 - 200 s, such as 1 s, 3 s, 5 s, 8 s, 10 s, 30 s, 50 s, 80 s, 100 s, 110 s, 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, 180 s, 190 s or 200 s, etc., so that the bonding strength ≥ 2 J / m 2 .

[0042] Preferably, the temperature for the hydrophilic bonding is 15 - 35 °C, such as 15 °C, 18 °C, 20 °C, 23 °C, 25 °C, 28 °C, 30 °C, 32 °C or 35 °C, etc.

[0043] Preferably, the temperature for the strengthening annealing is 100 - 350 °C, such as 100 °C, 120 °C, 150 °C, 180 °C, 200 °C, 230 °C, 250 °C, 280 °C, 300 °C, 330 °C or 350 °C, etc., and the time ≥ 10 min, such as 10 min, 12 min, 15 min, 18 min, 20 min, 23 min, 25 min, 28 min or 30 min, etc.

[0044] As a preferred technical solution of the present invention, in step A4, the temperature of the debonding annealing is 350 - 1250 °C, such as 350 °C, 380 °C, 400 °C, 420 °C, 450 °C, 470 °C, 500 °C, 530 °C, 550 °C, 580 °C, 600 °C, 620 °C, 650 °C, 680 °C, 700 °C, 730 °C, 750 °C, 775 °C, 800 °C, 825 °C, 850 °C, 875 °C, 900 °C, 925 °C, 950 °C, 975 °C, 1000 °C, 1025 °C, 1050 °C, 1075 °C, 1100 °C, 1125 °C, 1150 °C, 1175 °C, 1200 °C, 1225 °C or 1250 °C, etc.

[0045] In a second aspect, the present invention provides a method for preparing a composite substrate, and the preparation method includes the following steps:

[0046] B1. Provide two silicon substrates, respectively serving as a support substrate and a functional substrate, and complete the temporary bonding according to the temporary bonding and debonding method described in the first aspect to obtain a temporary bonded body;

[0047] B2. Thin the functional substrate in the obtained temporary bonded body;

[0048] B3. Provide a target substrate, and permanently bond the thinned functional substrate in the temporary bonded body to the target substrate to obtain a bonded intermediate;

[0049] B4. Complete the debonding according to the temporary bonding and debonding method described in the first aspect, and remove the support substrate to obtain a bonded body;

[0050] B5. Remove the silicon oxide layer on the functional substrate in the obtained bonded body to obtain a composite substrate.

[0051] Based on the advantages of the temporary bonding and debonding method of the present invention, it is convenient to process the functional substrate in the temporary bonded body. In particular, the functional substrate can be extremely thinned (e.g., up to the order of 1 micron, which can be measured by a finished film thickness gauge). Then, through the preparation method of the composite substrate, this ultra-thin functional substrate (film) can be transferred to the target substrate by permanent bonding, and then the temporary bonding is released, thereby preparing a composite substrate with a thin film. In the prior art, a composite substrate with a thin film can also be prepared through ion implantation peeling and permanent bonding technology. The method is as follows: Ion implantation is directly started on one side of the permanent bonding surface of the functional substrate, with an implantation depth of about 1 micron. Then, the ion-implanted functional substrate is permanently bonded to the target substrate, and the ion implantation layer is cracked through high-temperature treatment, so as to transfer the functional substrate of about 1 micron to the target substrate to form a composite substrate. However, the problem with this method is that ion implantation will cause direct damage and loss to the functional substrate (film layer) to be transferred. The preparation method of the composite substrate of the present invention does not have this problem, and there are no lattice defects in the functional substrate caused by ion implantation, and the crystal quality of the obtained "film" layer is higher.

[0052] As a preferred technical solution of the present invention, in step B2, the thinning method includes grinding thinning and / or ion implantation peeling.

[0053] Preferably, the grinding thinning method includes polishing.

[0054] Preferably, the ion implantation peeling method includes implanting hydrogen ions on the side of the functional substrate away from the temporary bonding interface to form a damaged layer, performing high-temperature peeling to crack the damaged layer, removing the part peeled off from the functional substrate, and then polishing the surface of the functional substrate to complete thinning and obtain a thinned functional substrate.

[0055] It should be emphasized that on the basis of realizing temporary bonding in the present invention, when using ion implantation peeling to thin the functional substrate, the part peeled off is the part that has undergone ion implantation, that is, the damaged part. After this part is removed, the thinned functional substrate in the temporary bonded body is undamaged, and a high-quality ultra-thin functional substrate can be formed after polishing.

[0056] Preferably, the peeling temperature of the high-temperature peeling is 700 - 1150 °C, such as 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C, 1050 °C, 1100 °C, 1120 °C or 1150 °C, etc.

[0057] Preferably, the peeling temperature of the ion implantation peeling is lower than the temperature of the debonding annealing.

[0058] It should be noted that in order to avoid the overlap between the stripping temperature for ion implantation stripping and the debonding annealing temperature range for debonding in the present invention, which may have an adverse effect on the already completed temporary bonding. Therefore, temperature matching is required to make the debonding temperature higher than the stripping temperature of high-temperature stripping, so as to ensure that the stripped part can be separated, while the thinned functional substrate remains temporarily bonded to the support substrate. Specifically, the stripping temperature of ion implantation stripping and / or the debonding annealing temperature of temporary bonding can be changed by adjusting the dose and implantation depth of ion implantation to change the temperature required for ions to precipitate from the silicon oxide layer. Similarly, if other processing techniques that require high-temperature treatment are to be performed on the functional substrate after temporary bonding, then it is only necessary to ensure that the temperature of these high-temperature treatments is lower than the debonding temperature.

[0059] As a preferred technical solution of the present invention, in step B3, the material of the target substrate includes at least one of diamond, gallium nitride, or silicon carbide.

[0060] As a preferred technical solution of the present invention, in step B3, the method of permanent bonding includes any one of hydrophilic bonding, room-temperature bonding, or thermocompression bonding.

[0061] As a preferred technical solution of the present invention, in step B3, if hydrophilic bonding is selected as the method of permanent bonding, after permanent bonding, annealing is required to increase the strength of the permanent bonding. The annealing temperature is 100 - 300 °C, such as 100 °C, 120 °C, 150 °C, 180 °C, 200 °C, 220 °C, 250 °C, 280 °C, or 300 °C, etc., and the time is ≥ 10 min, such as 10 min, 13 min, 15 min, 18 min, 20 min, 23 min, 25 min, 28 min, or 30 min, etc.

[0062] It should be noted that the purpose of step B3 in the method for preparing the composite substrate of the present invention is to achieve the permanent bonding of the target substrate and the functional substrate. Therefore, the methods of permanent bonding in the art are all applicable to perform the permanent bonding. According to the selection of the specific method of permanent bonding, annealing can be considered to enhance the effect of permanent bonding. Generally speaking, for the two methods of room-temperature bonding and thermocompression bonding, subsequent annealing may not be required, and those skilled in the art can make reasonable adjustments and selections according to the actual situation.

[0063] In the third aspect, a composite substrate is provided, and the composite substrate is obtained according to the method for preparing the composite substrate described in the second aspect.

[0064] In the fourth aspect, the present invention provides a method for manufacturing a wafer, and the method for manufacturing the wafer includes the following steps:

[0065] C1. Provide two silicon substrates, which serve as a support substrate and a functional substrate respectively, and complete temporary bonding according to the temporary bonding and debonding method described in the first aspect to obtain a temporary bonded body;

[0066] C2. The non-temporary bonding surface of the functional substrate has a circuit structure, or the non-temporary bonding surface of the functional substrate is thinned and a circuit structure is processed to form a functional wafer;

[0067] C3. Provide a target wafer, and permanently bond the functional wafer in the temporary bonded body to the target wafer to obtain a bonded intermediate;

[0068] C4. According to the temporary bonding and debonding method described in the first aspect, complete debonding of the bonded intermediate, remove the support substrate, and obtain a bonded body;

[0069] C5. Remove the silicon oxide layer on the functional wafer in the obtained bonded body to obtain a composite wafer.

[0070] Based on the advantages of the temporary bonding and debonding method described in the present invention, it is convenient to extremely thin the functional substrate in the temporary bonded body and implement other processing techniques. Furthermore, a circuit structure can be processed in the thinned functional substrate to form a functional wafer through the wafer manufacturing method, and permanent bonding can be performed on the functional wafer to obtain a composite wafer. Of course, the functional substrate may have an original circuit structure before temporary bonding, so there is no need to process the circuit structure after temporary bonding. At this time, the functional substrate with the original circuit structure has been transformed into the functional wafer when a temporary bonded body is formed through temporary bonding, or after a temporary bonded body is formed through temporary bonding, it can be transformed into a functional wafer only by thinning.

[0071] It can be understood that the non-temporary bonding surface refers to the other surface opposite to the temporary bonding surface.

[0072] As a preferred technical solution of the present invention, in step C3, the target wafer may or may not have a circuit structure.

[0073] Preferably, the target wafer further has an RDL layer disposed on the circuit structure.

[0074] In the present invention, the target wafer includes the following three cases: First, the target wafer has no circuit structure and its function is only heat dissipation, and it is permanently bonded to the functional wafer with a circuit structure; Second, the target wafer has a circuit structure and is permanently bonded to the functional wafer with a circuit structure; Third, the target wafer has a circuit structure and an RDL layer is disposed on the circuit structure, and then it is permanently bonded to the functional wafer.

[0075] Preferably, the manufacturing method further includes step C6 of preparing an RDL layer on the functional wafer of the obtained composite wafer, and then using the composite wafer provided with the RDL layer as the target wafer, repeating steps C1 to C5 to perform stacked bonding until the target number of layers is reached, thereby obtaining a multi-layer composite wafer.

[0076] Preferably, step C6 further includes thinning the functional wafer before preparing the RDL layer on the functional wafer to remove part of the silicon layer to expose the circuit structure in the functional wafer.

[0077] Preferably, the method for preparing the RDL layer includes forming a dielectric layer on the functional wafer, then making vias in the dielectric layer, and then filling the vias with a conductive medium to form metal wirings so that the vias have an electrical connection function; using the obtained composite wafer as the target wafer, repeating steps C1 to C5, and performing the permanent bonding on one side of the RDL layer.

[0078] Preferably, the material of the dielectric layer includes at least one of SiO 2 , SiN or SiCN.

[0079] The purpose of step C6 in the manufacturing method of the wafer according to the present invention is to continue stacking more functional wafers on the functional wafer that has been permanently bonded to the target wafer, that is, using the temporary bonding and debonding method of the present invention to "hold" and "grab" a new functional wafer and permanently bond it to the functional wafer existing in the composite wafer, thereby realizing stacked bonding. Therefore, the target number of layers can be adjusted according to the actual design and requirements until a multi-layer composite wafer (multi-layer wafer bonding structure) is obtained. That is, the multi-layer composite wafer refers to a functional wafer with at least two layers stacked on the initial target wafer.

[0080] It should be noted that before the two functional wafers are permanently bonded, an RDL layer (redistribution layer) is required to connect the circuits of the two functional wafers. Therefore, it is necessary to thin the functional wafers that have been bonded in the composite wafer to remove part of the silicon layer to expose the circuit wiring in the functional wafers, and then prepare an RDL layer thereon to realize the extension and connection of the circuit structure and prepare for bonding a new functional wafer.

[0081] The composite wafer and the multi-layer composite wafer obtained by the manufacturing method of the wafer of the present invention have obvious advantages. That is, in 2.5D and 3D packaging, multi-layer circuits can be stacked by means of stacked bonding, and the interconnection between multi-layer circuits is preferably interconnected by vias. When the functional wafer is made very thin, the length of the via will be shortened, which will greatly reduce the signal transmission time and the generation of heat, thereby improving the performance of the device or chip. Thinning the functional wafer can also reduce the volume of the subsequent prepared device or chip, adapting to the development trend of device miniaturization.

[0082] As a preferred technical solution of the present invention, the functional wafer and the target wafer are respectively provided with corresponding bonding alignment marks.

[0083] As a preferred technical solution of the present invention, before the functional wafer and the target wafer are permanently bonded, the functional wafer is first cut to form functional chips, the defective functional chips are removed, and then the remaining qualified functional chips are respectively permanently bonded to the target wafer to obtain the bonded intermediate.

[0084] As a preferred technical solution of the present invention, in step C3, the manufacturing method of the initial target wafer includes providing a silicon substrate, processing a circuit structure on the silicon substrate to form an initial target wafer; the method of processing the circuit structure includes photolithography.

[0085] It should be noted that the method of thinning the functional substrate in step C2 can be the same as step B2 of the preparation method of a composite substrate described in the second aspect of the present invention. The specific solution has been described in the second aspect and will not be repeated here.

[0086] It should be noted that the method of permanent bonding in step C3 can be the same as step B3 of the preparation method of a composite substrate described in the second aspect of the present invention. The specific solution has been described in the second aspect and will not be repeated here.

[0087] In the fifth aspect, the present invention provides a wafer, which includes at least two stacked wafer layers and is obtained according to the manufacturing method described in the fourth aspect.

[0088] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0089] The substrates of the temporary bonding and debonding method described in the present invention are all silicon substrates. Being made of silicon can effectively avoid warping or breaking problems caused by differences in thermal expansion coefficients, greatly reducing the risk of damage to the temporary bonding structure due to different thermal expansion coefficients. The present invention does not need to introduce a bonding medium, avoiding the problem of limited high-temperature processes caused by the bonding medium. The flatness, temperature tolerance of the temporary bonding surface, and the strength of the temporary bonding interface have been greatly improved. It can also avoid impurity contamination and cleaning problems caused by the bonding medium.

[0090] Based on the advantages of the temporary bonding and debonding method described in the present invention, it is convenient to greatly thin the functional substrate. Furthermore, through the preparation method of the composite substrate, this ultra-thin functional substrate (film) with a thickness of up to the micron level can be transferred onto the target substrate, thereby preparing a composite substrate with a film. It avoids lattice defects caused by ion implantation, and the crystal quality of the obtained "film" layer is higher.

[0091] Furthermore, through the manufacturing method of the wafer, the manufacturing of multi-layer composite wafers can be realized in a stacked bonding manner and process. And the ultra-thin functional wafer is beneficial to greatly reduce the signal transmission time and heat generation, thereby improving the performance of the device or chip. Thinning the functional wafer can also reduce the volume of the subsequent prepared device or chip, thus adapting to the development trend of device miniaturization. Description of the Drawings

[0092] Figure 1 It is a schematic flow chart of a temporary bonding and debonding method in Embodiment 1.

[0093] Figure 2 It is a schematic flow chart of a preparation method of a composite substrate in Application Example 1.

[0094] Figure 3 It is a schematic flow chart of a manufacturing method of a wafer in Application Example 3.

[0095] In the figure: 10 - silicon substrate, 11 - support substrate, 12 - functional substrate, 13 - functional wafer, 20 - silicon oxide layer, 30 - temporary bonding interface, 40 - temporary bonded body, 50 - target substrate, 51 - target wafer, 60 - composite substrate, 61 - composite wafer, 62 - multi-layer composite wafer, 70 - RDL layer, 71 - dielectric layer, 72 - via hole, 73 - conductive medium. Detailed Embodiments

[0096] The technical solutions of the present invention will be further described below through specific embodiments.

[0097] Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0098] Example 1

[0099] This example provides a method for temporary bonding and debonding, as Figure 1 shown, including the following steps:

[0100] A1. Prepare two silicon substrates 10, and respectively prepare silicon oxide layers 20 on the two silicon substrates 10 by thermal oxidation. The thickness of the silicon oxide layer 20 is 800 nm;

[0101] A2. Flatten the surface of the silicon oxide layer 20 to make the surface roughness within 1 nm, and then respectively inject hydrogen ions into the silicon oxide layers 20 of the two silicon substrates 10 by ion implantation. The implantation energy is 40 keV, and the implantation dose is 5×10 15 ions / cm 2 , and the implantation depth is 460 nm to form an ion implantation layer within the silicon oxide layer 20;

[0102] Perform a first cleaning on the silicon substrate 10 after ion implantation. The first cleaning method is to perform tank cleaning in sequence with a mixed solution of ammonia water, hydrogen peroxide and deionized water, and then perform tank cleaning with a mixed solution of hydrochloric acid, hydrogen peroxide and deionized water to remove surface impurities;

[0103] For the silicon substrate 10 after the first cleaning, perform hydrofluoric acid treatment with a hydrofluoric acid solution with a mass percentage concentration of 20%. The treatment temperature is 35 °C, and the treatment time is 57 s. Then, perform a second cleaning on the surface of the silicon substrate 10 with deionized water to remove the residual solution on the surface, and then spin-dry at high speed;

[0104] After the second cleaning, use plasma activation technology to perform plasma activation on the temporary bonding surfaces of the two silicon substrates 10, that is, the surfaces of the silicon oxide layers 20, to generate dangling hydroxyl groups and active sites on the temporary bonding surfaces. The activation gas is Ar gas;

[0105] For the silicon substrate 10 after plasma activation, perform a third cleaning with deionized water to remove the particles on the surface of the silicon substrate 10 and reduce the voids formed at the subsequent temporary bonding interface 30 due to particles;

[0106] A3. After the third cleaning, bring the temporary bonding surfaces of the two silicon substrates 10 into contact, and perform hydrophilic bonding by means of planar pressing at room temperature. The pressure is 420 N, and keep it for 80 s to form a temporary bonded body 40,

[0107] Place the temporary bonded body 40 at 280 °C for enhanced annealing for 25 min to increase the temporary bonding strength. After annealing, complete the temporary bonding, and the temporary bonding strength is greater than 2 J / m 2 ;

[0108] When debonding, the temporary bonded body 40 that has completed temporary bonding is placed at 730 °C for debonding annealing to complete debonding.

[0109] Example 2

[0110] This example provides a method for temporary bonding and debonding. In step (A2) of the method, the implantation dose is adjusted to 1×10 15 ions / cm 2 , the implantation depth is 600 nm, and the temperature of the debonding annealing in step A4 is adjusted from 730 °C to 1000 °C. Except for the above, other conditions are exactly the same as those in Example 1.

[0111] Comparative Example 1

[0112] This comparative example provides a method for temporary bonding and debonding. In step A2 of the method, hydrofluoric acid treatment is not performed, that is, the silicon substrate 10 after the first cleaning is directly subjected to plasma activation. Except for the above, other conditions are exactly the same as those in Example 1.

[0113] Comparative Example 2

[0114] This comparative example provides a method for temporary bonding and debonding. In step A2 of the method, hydrofluoric acid treatment is first performed and then ion implantation is carried out. That is, on one side of the silicon oxide layer 20 of the two silicon substrates 10 obtained in step A1, hydrofluoric acid treatment is carried out using a hydrofluoric acid solution with a mass percentage concentration of 20%, the treatment temperature is 35 °C, and the treatment time is 57 s. Then, the surface of the silicon substrate 10 is subjected to a second cleaning with deionized water to remove the residual solution on the surface, and then spin-dried at high speed; then, hydrogen ions are respectively implanted into the silicon oxide layer 20 of the two silicon substrates 10 that have undergone the second cleaning by ion implantation. The implantation energy is 40 keV, and the implantation dose is 5×10 15 ions / cm 2 , the implantation depth is 460 nm, and an ion implantation layer is formed in the silicon oxide layer 20; the silicon substrate 10 after ion implantation is subjected to the first cleaning. The first cleaning method is to perform tank cleaning successively with a mixed solution of ammonia water, hydrogen peroxide and deionized water, and then perform tank cleaning with a mixed solution of hydrochloric acid, hydrogen peroxide and deionized water to remove surface impurities; then, the two silicon substrates 10 after the first cleaning are subjected to plasma activation. Except for the above, other conditions are exactly the same as those in Example 1.

[0115] In the methods of temporary bonding and debonding in Embodiment 1 and Embodiment 2 of the present invention, not only can the strength and stability of the temporary bonding be ensured, but also when performing debonding annealing, hydrogen atoms can move between the lattices of the silicon oxide layer 20, flow through the channels formed by hydrofluoric acid treatment from the ion implantation layer, and precipitate onto the temporary bonding interface 30. Hydrogen gas is formed through recombination and uniform bubbles are formed at the temporary bonding interface 30, causing the temporary bonding interface 30 to crack, and enabling the silicon oxide layers 20 of the two silicon substrates 10 to be completely and effectively separated at the temporary bonding interface 30. When performing debonding in Comparative Example 1 and Comparative Example 2, as the temperature increases, the ion implantation layer in the silicon oxide layer 20 cracks in situ, and this cracking force is uneven, resulting in the fragmentation of the thinned functional substrate 12 attached thereto. Therefore, the methods of temporary bonding and debonding in Embodiment 1 and Embodiment 2 are used for subsequent applications.

[0116] Application Example 1

[0117] This application example provides a method for preparing a composite substrate, as Figure 2 shown, the preparation method includes the following steps:

[0118] B1. Provide two silicon substrates 10, respectively serving as a support substrate 11 and a functional substrate 12, and complete temporary bonding according to the method of temporary bonding and debonding described in Embodiment 1 to obtain a temporary bonded body 40;

[0119] B2. Grind and thin the functional substrate 12 in the obtained temporary bonded body 40 using chemical mechanical polishing until the thickness reaches 1 μm;

[0120] B3. Provide a target substrate 50, the material of the target substrate 50 is diamond, and perform room-temperature bonding between the thinned functional substrate 12 in the temporary bonded body 40 and the target substrate 50 to complete permanent bonding to obtain a bonded intermediate;

[0121] B4. Complete debonding according to the method of temporary bonding and debonding described in Embodiment 1, and remove the support substrate 11 to obtain a bonded body;

[0122] B5. Remove the silicon oxide layer 20 on the functional substrate 12 in the obtained bonded body to obtain a composite substrate 60.

[0123] Application Example 2

[0124] This application example provides a method for preparing a composite substrate. In steps B1 and B4 of the preparation method, temporary bonding and debonding are respectively completed according to the method of temporary bonding and debonding described in Embodiment 2, and in step B2, the ion implantation peeling method is used to replace the chemical mechanical polishing method;

[0125] The method of ion implantation and peeling includes performing hydrogen ion implantation on one side of the functional substrate 12 away from the temporary bonding interface 30 to form a damaged layer, performing high-temperature peeling at 900 °C to crack the damaged layer, removing the peeled part from the functional substrate 12, and then polishing the surface of the functional substrate 12 to complete thinning, obtaining a thinned functional substrate 12 with a thickness of 1 μm;

[0126] Except for the above, other conditions are exactly the same as those in Application Example 1.

[0127] Application Example 3

[0128] This application example provides a method for manufacturing a wafer, as Figure 3 shown, the method for manufacturing the wafer includes the following steps:

[0129] C1. Provide two silicon substrates 10, respectively serving as a support substrate 11 and a functional substrate 12, and complete temporary bonding according to the method of temporary bonding and debonding described in Embodiment 1 to obtain a temporary bonded body 40;

[0130] C2. Thin the non-temporary bonding surface of the functional substrate 12 in the obtained temporary bonded body 40, process the circuit structure and bonding alignment marks to form a functional wafer 13; cut the functional wafer 13 and remove defective parts;

[0131] C3. Provide another silicon substrate 10, process the circuit structure and bonding alignment marks on this silicon substrate 10 by photolithography to form an initial target wafer 51; hydrophilically bond the functional wafer 13 in the temporary bonded body 40 to the target wafer 51 to complete permanent bonding, and then anneal at 260 °C for 15 min to obtain a bonded intermediate;

[0132] C4. According to the method of temporary bonding and debonding described in Embodiment 1, complete the debonding of the bonded intermediate and remove the support substrate 11 to obtain a bonded body;

[0133] C5. Remove the silicon oxide layer 20 on the functional wafer 13 in the obtained bonded body to obtain a composite wafer 61;

[0134] In the composite wafer 61, an RDL layer 70 is fabricated on the surface of the functional wafer 13 that is farthest from the initial target wafer 51. Specifically, the functional wafer 13 is first thinned to remove a part of the silicon layer to expose the circuit structure in the functional wafer 13. Then, a dielectric layer 71 is formed on the functional wafer 13. The dielectric layer 71 is made of SiN. Then, vias 72 are fabricated in the dielectric layer 71, and a conductive dielectric 73 is filled in the vias 72 to form metal wirings, enabling the vias 72 to have an electrical connection function. Then, the obtained composite wafer 61 is used as the target wafer 51, and steps C1 to C5 are repeated. The permanent bonding is performed on one side of the RDL layer 70 until a multi-layer composite wafer 62 with the target number of layers is obtained.

[0135] Application Example 4

[0136] This application example provides a method for manufacturing a wafer. In the method for manufacturing the wafer:

[0137] C1. Provide two silicon substrates 10, respectively as a support substrate 11 and a functional substrate 12. Complete the temporary bonding according to the method of temporary bonding and debonding in Embodiment 1 to obtain a temporary bonded body 40.

[0138] C2. The functional substrate 12 in the obtained temporary bonded body 40 has an original circuit structure. The original circuit structure is formed by processing the circuit structure and bonding alignment marks on the silicon substrate 10 by photolithography before temporary bonding to form an initial functional substrate 12. At this time, the functional substrate 12 in the obtained temporary bonded body 40 is a functional wafer 13.

[0139] C3. Provide another silicon substrate 10 without a circuit structure as an initial target wafer 51. Hydrophilic bond the functional wafer 13 in the temporary bonded body 40 to the target wafer 51 to complete the permanent bonding, and then perform annealing at 260 °C for 15 min to obtain a bonding intermediate.

[0140] C4. According to the method of temporary bonding and debonding in Embodiment 1, complete the debonding of the bonding intermediate and remove the support substrate 11 to obtain a bonded body.

[0141] C5. Remove the silicon oxide layer 20 on the functional wafer 13 in the obtained bonded body to obtain a composite wafer 61.

[0142] In the composite wafer 61, an RDL layer 70 is fabricated on the surface of the functional wafer 13 that is farthest from the initial target wafer 51. Specifically, the functional wafer 13 is first thinned by removing a portion of the silicon layer to expose the circuit structure in the functional wafer 13. Then, a dielectric layer 71 made of SiN is formed on the functional wafer 13. Next, vias 72 are fabricated in the dielectric layer 71, and then conductive medium 73 is filled in the vias 72 to form metal wiring, enabling the vias 72 to have an electrical connection function. Then, the obtained composite wafer 61 is used as the target wafer 51, and steps C1 to C5 are repeated, and the permanent bonding is implemented on one side of the RDL layer 70 until a multi-layer composite wafer 62 with the target number of layers is obtained.

[0143] As can be seen from the above, in the method of temporary bonding and debonding of the present invention, on the one hand, both substrates are made of silicon (homogeneous material), which can effectively avoid warping or breaking problems caused by differences in thermal expansion coefficients. The supporting substrate and the functional substrate made of silicon have high consistency in thermal properties, and their degrees of thermal expansion and contraction under various temperature conditions are relatively close, thus greatly reducing the risk of damage to the bonding structure due to different thermal expansion coefficients.

[0144] On the other hand, no bonding medium needs to be introduced at the bonding interface between the supporting substrate and the functional substrate. The advantages of this design are as follows: First, it can avoid the problem of limited high-temperature processes caused by the use of bonding media. Second, it can solve the problem of difficulty in reducing the thickness of the functional substrate. Since there is no bonding medium, it is easier to operate and control when thinning the functional substrate. Finally, it can also avoid the problems of impurity contamination and cleaning brought by the bonding medium, as well as the problem of adverse effects on product performance in subsequent processes.

[0145] On the other hand, based on the advantages and characteristics that the functional substrate can be made very thin by the method of temporary bonding and debonding, a composite substrate with an ultra-thin functional substrate (film) can be obtained by using the preparation method of the composite substrate. Further, through the manufacturing method of the wafer, a multi-layer bonded wafer obtained by repeating multi-layer bonding many times can greatly reduce the thickness of the finished device, meeting the requirements of device miniaturization and multi-functionality.

[0146] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0147] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0148] In addition, any combinations can be made among various different embodiments of the present invention, as long as they do not violate the idea of the present invention, and they should equally be regarded as the content disclosed by the present invention.

Claims

1. A temporary bonding and debonding method, characterized in that: The steps include: A1. Providing two silicon substrates, forming a silicon oxide layer on one side of the silicon substrate; A2. Sequentially ion implanting the silicon oxide layer, treating with hydrofluoric acid and plasma activation to form a temporary bonding surface; A3. The temporary bonding surfaces are contacted to perform hydrophilic bonding, and then annealed to form a temporary bonding body between the two silicon substrates to complete the temporary bonding; A4. Performing debonding annealing on the temporary bonded body to separate the silicon oxide layers of the two silicon substrates at the temporary bonding interface, thereby completing debonding.

2. The temporary bonding and debonding method according to claim 1, characterized in that: In step A1, the method for forming the silicon oxide layer includes thermal oxidation; the thickness of the silicon oxide layer is 1-1000 nm.

3. The temporary bonding and debonding method according to claim 1, characterized in that: In step A2, before the ion implantation, the surface of the silicon oxide layer is planarized to make the surface roughness ≤1nm; the ion elements of the ion implantation include hydrogen ions; the implantation energy of the ion implantation is 1-80keV, and the implantation dose is 1×10 13 ~8×10 16 ions / cm 2 , the injection depth is 0.1~1000nm.

4. The temporary bonding and debonding method according to claim 1, characterized in that: In step A2, the hydrofluoric acid treatment method includes immersion in a hydrofluoric acid solution, wherein the mass percentage concentration of the hydrofluoric acid solution is 0.1% to 30%; the temperature of the hydrofluoric acid treatment is 10 to 50° C., and the time is 1 to 100 seconds.

5. The temporary bonding and debonding method according to claim 1, characterized in that: In step A2, the gas used to generate plasma during the plasma activation includes at least one of N2, O2, Ar or He.

6. The temporary bonding and debonding method according to claim 1, characterized in that: In step A3, the hydrophilic bonding method includes a center point pressurization method or a plane pressurization method; the pressurization pressure of the hydrophilic bonding is 1~1000N, and the pressurization holding time is 1~200s; the temperature of the hydrophilic bonding is 15~35℃.

7. The temporary bonding and debonding method according to claim 1, characterized in that: In step A3, the strengthening annealing temperature is 100-350°C and the time is ≥10min; In step A4, the temperature of the debonding annealing is 350-1250°C.

8. A method for preparing a composite substrate, characterized in that: The preparation method comprises the following steps: B1. Providing two silicon substrates, respectively, as a support substrate and a functional substrate, and completing temporary bonding according to any one of claims 1 to 7 and the method for temporarily bonding and debonding to obtain a temporary bonded body; B2. Thinning the functional substrate in the resulting temporary bond; B3 provides a target substrate, the thinned functional substrate in the temporary bonding body is permanently bonded to the target substrate to obtain a bonding intermediate; B4. Debonding is completed by the temporary bonding and debonding method according to any one of claims 1 to 7, removing the supporting substrate to obtain a bonded body; B5. Remove the silicon oxide layer on the functional substrate in the obtained bonded body to obtain a composite substrate.

9. The method for preparing a composite substrate according to claim 8, characterized in that: In step B2, the thinning method includes grinding thinning and / or ion implantation stripping; the stripping temperature of the ion implantation stripping is lower than the temperature of the debonding annealing; In step B3, the material of the target substrate includes at least one of diamond, gallium nitride or silicon carbide.

10. A composite substrate, characterized in that: Obtained according to the method for preparing the composite substrate according to claim 8 or 9.

11. A method for manufacturing a wafer, characterized in that: The wafer manufacturing method comprises the following steps: C1. Providing two silicon substrates, respectively as a support substrate and a functional substrate, and completing temporary bonding according to the temporary bonding and debonding method according to any one of claims 1 to 7 to obtain a temporary bonded body; C2. The non-temporary bonding surface of the functional substrate has an original circuit structure, or the non-temporary bonding surface of the functional substrate is thinned and processed to form a functional wafer; C3 provides a target wafer, the functional wafer in the temporary bonding body is permanently bonded to the target wafer to obtain a bonding intermediate; C4. The temporary bonding and debonding method according to any one of claims 1 to 7, wherein the bonded intermediate is debonded, the support substrate is removed, and a bonded body is obtained; C5. Removing the silicon oxide layer on the functional wafer in the resulting bonded body to obtain a composite wafer.

12. The method for manufacturing a wafer according to claim 11, characterized in that: In step C3, the target wafer has a circuit structure; the target wafer also has an RDL layer arranged on the circuit structure.

13. The method for manufacturing a wafer according to claim 12, characterized in that: The manufacturing method further comprises step C6, preparing an RDL layer on the functional wafer of the obtained composite wafer, and then using the composite wafer provided with the RDL layer as the target wafer, repeating steps C1 to C5 to perform stacking bonding until the target number of layers is reached, thereby obtaining a multi-layer composite wafer; Before preparing the RDL layer on the functional wafer, the functional wafer is thinned to remove part of the silicon layer so as to expose the circuit structure in the functional wafer.

14. The method for manufacturing a wafer according to claim 12 or 13, characterized in that: The method for preparing the RDL layer includes forming a dielectric layer on the functional wafer, then making a through hole in the dielectric layer, and then filling the through hole with a conductive medium to form a metal wiring so that the through hole has an electrical connection function; using the obtained composite wafer as the target wafer, repeating steps C1 to C5, and performing the permanent bonding on one side of the RDL layer; The material of the dielectric layer includes at least one of SiO2, SiN or SiCN.

15. The method for manufacturing a wafer according to claim 11, characterized in that: The functional wafer and the target wafer are also provided with corresponding bonding alignment marks respectively.

16. The method for manufacturing a wafer according to claim 11, characterized in that: Before the functional wafer is permanently bonded to the target wafer, the functional wafer is first cut to form functional chips, and defective functional chips are removed. Then, the remaining qualified functional chips are permanently bonded to the target wafer one by one to obtain the bonding intermediate.

17. A wafer, characterized in that: Comprising at least two stacked wafer layers, obtained according to the manufacturing method according to any one of claims 11-16.

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