Semiconductor structure and method for forming the same

Abstract

The present invention relates to a semiconductor structure and a method for forming the same, the semiconductor structure comprising: a first substrate; a first adhesion layer located on the surface of the first substrate; a first buffer layer located on the surface of the first adhesion layer; a first bonding layer located on the surface of the first buffer layer, the density of the first adhesion layer and the first buffer layer are both greater than the density of the first bonding layer, and the materials of the first bonding layer and the first buffer layer are both dielectric materials containing C elements. The first adhesion layer of the semiconductor structure has high adhesion to the first substrate and the first buffer layer, and between the first buffer layer and the first bonding layer to avoid fracture; and the first bonding layer can also have a strong bonding force on the bonding surface after bonding, which can block the diffusion of metal materials at the bonding interface, and is conducive to improving the performance of the semiconductor structure.

Description

[0001] The filing date of the parent application of this divisional application is June 29, 2018, the application number is 201880096607.0, and the name of the invention is “Semiconductor structure and method for forming the same”. Technical Field

[0002] The present invention relates to the field of semiconductor technology, and in particular to a semiconductor structure and a method for forming the same. Background Art

[0003] In 3D chip technology platforms, two or more wafers with semiconductor devices are usually bonded together through wafer bonding technology to improve the integration of the chip. In the existing wafer bonding technology, a bonding film is formed on the bonding surface of the wafer, and the two layers of wafers are bonded together through the bonding film surface to achieve wafer bonding.

[0004] In the prior art, silicon oxide and silicon nitride films are usually used as bonding films, but the bonding strength is insufficient, which leads to defects in the process and affects the product yield.

[0005] In addition, a metal connection structure is formed in the bonding film. During the hybrid bonding process, the metal connection structure is prone to diffusion at the bonding interface, which affects product performance.

[0006] Therefore, how to improve the quality of wafer bonding is a problem that needs to be solved urgently. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a semiconductor structure and a method for forming the same, so as to improve the bonding quality.

[0008] To solve the above problems, the present invention provides a semiconductor structure, including: a first substrate; a first adhesion layer located on the surface of the first substrate; a first buffer layer located on the surface of the first adhesion layer; a first bonding layer located on the surface of the first buffer layer, wherein the density of the first adhesion layer and the first buffer layer are both greater than the density of the first bonding layer, and the materials of the first bonding layer and the first buffer layer are both dielectric materials containing the C element.

[0009] Optionally, the atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer.

[0010] Optionally, the atomic concentration of C in the first bonding layer is greater than 35%, and the atomic concentration of C in the first buffer layer is 0-50%.

[0011] Optionally, in the first bonding layer, the atomic concentration of C increases as the thickness of the first bonding layer increases; in the first buffer layer, the atomic concentration of C increases as the thickness of the first buffer layer increases.

[0012] Optionally, the material of the first bonding layer also includes Si and N.

[0013] Optionally, the material of the first buffer layer also includes Si and N.

[0014] Optionally, a material of the first adhesion layer includes at least one of silicon nitride, silicon oxynitride and silicon oxide.

[0015] Optionally, the thickness of the first adhesion layer is The thickness of the first buffer layer is

[0016] Optionally, material components on both sides of the interface between the first bonding layer and the first buffer layer are substantially the same.

[0017] Optionally, it also includes: a second substrate, a second adhesion layer formed on the surface of the second substrate, a second buffer layer located on the surface of the second adhesion layer, and a second bonding layer located on the surface of the second buffer layer; the density of the second adhesion layer and the second buffer layer are both greater than the density of the second bonding layer; the second bonding layer is bonded and fixed relative to the surface of the first bonding layer.

[0018] Optionally, the second bonding layer is made of the same material as the first bonding layer, the second buffer layer is made of the same material as the first buffer layer, and the second adhesion layer is made of the same material as the first adhesion layer.

[0019] Optionally, it also includes: a first bonding pad penetrating the first bonding layer, the first buffer layer and the first adhesion layer; a second bonding pad penetrating the second bonding layer, the second buffer layer and the second adhesion layer; and the first bonding pad is bonded to the second bonding pad.

[0020] To solve the above problems, a specific embodiment of the present invention also provides a semiconductor structure, including: a first substrate; a first adhesion layer located on the surface of the first substrate; a first buffer layer located on the surface of the first adhesion layer, the material of the first buffer layer is a dielectric material containing the C element, and the atomic concentration of C in the first buffer layer increases with the increase of the thickness of the first buffer layer; a first bonding layer located on the surface of the first buffer layer, the material of the first bonding layer is a dielectric material containing the C element, and the atomic concentration of C in the first bonding layer increases with the increase of the thickness of the first bonding layer, and the density of the first adhesion layer and the first buffer layer are both greater than the density of the first bonding layer.

[0021] To solve the above problems, a specific embodiment of the present invention also provides a semiconductor structure, including: a first substrate; a first adhesion layer located on the surface of the first substrate; a first buffer layer located on the surface of the first adhesion layer, the material of the first buffer layer is a dielectric material containing the C element; a first bonding layer located on the surface of the first buffer layer, the material of the first bonding layer is a dielectric material containing the C element; wherein the atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer.

[0022] Optionally, atomic concentrations of H in the first adhesion layer and the first buffer layer are both smaller than atomic concentrations of H in the first bonding layer.

[0023] To solve the above problems, a specific embodiment of the present invention further provides a method for forming a semiconductor structure, comprising: providing a first substrate; forming a first adhesion layer on the surface of the first substrate, and plasma bombarding the first adhesion layer to reduce the atomic concentration of H; forming a first buffer layer on the surface of the first adhesion layer, wherein the material of the first buffer layer is a dielectric material containing the C element; forming a first bonding layer on the surface of the first buffer layer, wherein the material of the first bonding layer is a dielectric material containing the C element.

[0024] Optionally, the atomic concentration of H in the first adhesion layer and the first buffer layer is less than the atomic concentration of H in the first bonding layer.

[0025] Optionally, before the plasma bombardment, the first adhesion layer contains H bonds; in the plasma bombardment step, N-containing plasma is used for bombardment to reduce the H bonds in the first adhesion layer.

[0026] Optionally, the atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer.

[0027] Optionally, the material of the first bonding layer also includes Si and N.

[0028] Optionally, the material of the first buffer layer also includes Si and N.

[0029] Optionally, a material of the first adhesion layer includes at least one of silicon nitride, silicon oxynitride and silicon oxide.

[0030] Optionally, the thickness of the first adhesion layer is The thickness of the first buffer layer is

[0031] Optionally, the atomic concentration of C in the first bonding layer is greater than 35%, and the material components on both sides of the interface between the first bonding layer and the first buffer layer are substantially the same.

[0032] The semiconductor structure of the present invention has a first adhesion layer and a first buffer layer between the first substrate and the first bonding layer, and the density of the first adhesion layer and the first buffer layer is greater than the density of the first bonding layer, thereby improving the adhesion between the first adhesion layer and the first substrate, the first adhesion layer and the first buffer layer, and the first buffer layer and the first bonding layer, and avoiding fracture. Moreover, the materials of the first bonding layer and the first buffer layer are both dielectric materials containing C elements, and the first bonding layer can also have a strong bonding force on the bonding surface after bonding, and can block the diffusion of metal materials at the bonding interface, thereby improving the performance of the formed semiconductor structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figures 1 to 4 A schematic structural diagram of a semiconductor structure forming process according to a specific embodiment of the present invention;

[0034] Figure 5 It is a schematic structural diagram of a semiconductor structure according to a specific embodiment of the present invention;

[0035] Figure 6 It is a schematic structural diagram of a semiconductor structure according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0036] The specific implementation manner of the semiconductor structure and the method for forming the same provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Please refer to Figures 1 to 4 , which is a structural schematic diagram of the formation process of a semiconductor structure according to a specific embodiment of the present invention.

[0038] Please refer to Figure 1 , providing a first substrate 100.

[0039] The first base 100 includes a first semiconductor substrate 101 and a first device layer 102 formed on a surface of the first semiconductor substrate 101 .

[0040] The first semiconductor substrate 101 may be a single crystal silicon substrate, a Ge substrate, a SiGe substrate, a SOI or a GOI, etc.; according to the actual needs of the device, a suitable first semiconductor substrate 101 may be selected, which is not limited here. In this specific embodiment, the first semiconductor substrate 101 is a single crystal silicon wafer.

[0041] The first device layer 102 includes a semiconductor device formed on the semiconductor substrate 101, a metal interconnection structure connecting the semiconductor device, a dielectric layer covering the semiconductor device and the metal interconnection structure, etc. The dielectric layer is generally silicon oxide, silicon nitride or silicon oxynitride. The first device layer 102 can be a multi-layer or single-layer structure. In a specific embodiment, the first device layer 102 includes a dielectric layer and a 3D NAND structure formed in the dielectric layer.

[0042] Please refer to Figure 2 A first adhesion layer 202 , a first buffer layer 203 located on the surface of the first adhesion layer 202 , and a first bonding layer 201 located on the surface of the first buffer layer 203 are sequentially formed on the surface of the first substrate 100 .

[0043] The first adhesion layer 202, the first buffer layer 103 and the first bonding layer 201 may be formed in sequence by chemical vapor deposition processes. In this specific embodiment, the first adhesion layer 202, the first buffer layer 203 and the first bonding layer 201 are formed by plasma enhanced chemical vapor deposition process.

[0044] The material of the first adhesion layer 202 is a dielectric material having a density greater than that of the first bonding layer 201. The material of the first adhesion layer 202 may be at least one of silicon nitride, silicon oxynitride and silicon oxide. Based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first adhesion layer 202 may also be doped with at least one of elements such as O, H, P, and F.

[0045] In a specific embodiment, the material of the first adhesion layer 202 is silicon nitride, and the first adhesion layer 202 is formed by a plasma enhanced chemical vapor deposition process, and the reaction gases used include: SiH4 and NH3, the flow ratio of SiH4 and NH3 is in the range of (0.8-1.2):1, and the RF power range is 150W-300W. The first adhesion layer 202 with a higher density can be formed by adjusting the process parameters in the deposition process.

[0046] In other specific embodiments, the method for forming the first adhesion layer 202 includes: forming an adhesion material layer on the surface of the first substrate 100 by a deposition process, and then plasma bombarding the adhesion material layer to reduce the H content in the adhesion material layer, thereby improving the density of the formed first adhesion layer 202. The plasma bombardment can use N-containing gas, such as N2, NH3, etc. In a specific embodiment, the plasma bombardment can use N2 as a plasma source, the RF power is 500W, and the bombardment time is 30s. The H in the first adhesion layer 202 can be removed by the plasma bombardment, so that the first adhesion layer 202 has more chemical bonds per unit area that can connect adjacent material layers, such as Si-, N-, etc., thereby improving the adhesion between the first adhesion layer 202 and the first device layer 102 and the first buffer layer 203.

[0047] The material of the first buffer layer 203 is a dielectric material containing C element. In a specific embodiment, the first buffer layer 203 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first buffer layer 203 may also contain at least one of Si, N, O, H, P, F and other elements. The density of the first buffer layer 203 is greater than the density of the first bonding layer 201. In a specific embodiment, the density of the first buffer layer 203 is close to or the same as the density of the first adhesion layer 202. The material of the first buffer layer 203 can be carbon-doped silicon nitride, carbon-doped silicon oxide, nitrogen-doped carbon oxide, etc. Since the density of the first buffer layer 203 is relatively high, the density of chemical bonds on the interface with the first adhesion layer 202 is relatively high, so it has high adhesion with the first adhesion layer 202.

[0048] In a specific embodiment, the first buffer layer 203 is formed by a plasma enhanced chemical vapor deposition process, and the reaction gas used includes: one of trimethylsilane or tetramethylsilane and NH3, the flow ratio of trimethylsilane or tetramethylsilane to NH3 is in the range of 1:(2-4), and the RF power range is 200 W-500 W. The density of the first buffer layer 203 and the atomic concentration of C in the first buffer layer 203 can be adjusted by adjusting the deposition process parameters.

[0049] The material of the first bonding layer 201 is a dielectric material containing C element, and the atomic concentration of C in the first bonding layer 201 is greater than the atomic concentration of C in the first buffer layer 203. In one specific embodiment, the first bonding layer 201 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first bonding layer 201 may also contain at least one of Si, N, O, H, P, F and other elements. The material of the first bonding layer 201 may be carbon-doped silicon nitride, carbon-doped silicon oxide, nitrogen-doped carbon oxide and the like. The composition of the first bonding layer 201 is close to or the same as that of the first buffer layer 203. Therefore, forming the first bonding layer 201 on the surface of the first buffer layer 203 can make the first bonding layer 201 and the first buffer layer 203 have a higher adhesion. If the atomic concentration of C in the material layer is too high, the adhesion with other material layers will decrease. The atomic concentration of C in the first buffer layer 203 is lower than that in the first bonding layer 201 . Compared with forming the first bonding layer 201 directly on the surface of the first adhesion layer 202 , the adhesion between the first buffer layer 203 and the first adhesion layer 202 is higher.

[0050] In a specific embodiment, the first bonding layer 201 is formed by a plasma enhanced chemical vapor deposition process, and the reaction gases used include: at least one of trimethylsilane or tetramethylsilane and NH3, the flow ratio of trimethylsilane or tetramethylsilane to NH3 is in the range of (1.6 to 2.4):1, and the RF power range is 500W to 1100W.

[0051] The C in the first bonding layer 201 can effectively improve the bonding force between the first bonding layer 201 and other bonding layers during the bonding process. The higher the C concentration, the greater the bonding force generated when bonding with other bonding layers. In a specific embodiment, the atomic concentration of C in the first bonding layer 201 is greater than 35%.

[0052] The atomic concentration of C in the first buffer layer 203 is less than that in the first bonding layer 201, so that the material structure of the first buffer layer 203 is closer to that of the first adhesion layer 202. In a specific embodiment, the atomic concentration of C in the first buffer layer 203 is 0-50%.

[0053] Since the first bonding layer 201 contains a higher concentration of C element, the density of the first bonding layer 201 is relatively low. In the specific embodiment of the present application, a first adhesion layer 202 and a first buffer layer 203 with higher density are formed between the first bonding layer 201 and the first substrate 100, and the atomic concentration of C in the first buffer layer 203 is lower than the atomic concentration of C in the first bonding layer 201, which can improve the adhesion between the layers.

[0054] By controlling the formation process parameters of the first bonding layer 201, the first buffer layer 203 and the first adhesion layer 202, the concentration of each component in the first bonding layer 201 and the first adhesion layer 202 can be adjusted, and the adhesion and dielectric constant between the material layers can be adjusted.

[0055] Since the adhesion between different material layers is related to the material components on both sides of the interface, the closer the material components are, the stronger the adhesion is. In order to further enhance the adhesion between the first adhesion layer 202 and the first device layer 102, the process parameters can be gradually adjusted during the formation of the first adhesion layer 202, so that the concentration of the components in the first adhesion layer 202 gradually changes, so that the material components on both sides of the interface between the first device layer 102 and the first adhesion layer 202 are close. In a specific embodiment, during the formation of the first adhesion layer 202, as the thickness of the first adhesion layer 202 increases, the parameters of the deposition process are adjusted so that the atomic concentration of Si in the first adhesion layer 202 gradually changes as the thickness of the first adhesion layer 202 increases. In other specific embodiments, according to the different surface materials of the first device layer 102, the concentration of other components in the first adhesion layer 202 can also be adjusted. In other specific embodiments, during the formation of the first adhesion layer 202, the deposition process parameters can be kept unchanged so that the atomic concentration of each element in the first adhesion layer 202 remains consistent at different thickness positions.

[0056] In order to further enhance the adhesion between the first adhesion layer 202 and the first buffer layer 203, the process parameters can be gradually adjusted during the formation of the first buffer layer 203, so that the component concentration in the first buffer layer 203 gradually changes, so that the material components on both sides of the interface between the first buffer layer 203 and the first adhesion layer 202 are close. In a specific embodiment, in the process of forming the first buffer layer 203, as the thickness of the first buffer layer 203 increases, the parameters of the deposition process are adjusted so that the atomic concentration of C gradually increases with the increase of the thickness of the first buffer layer 203. In other specific embodiments, the atomic concentration of C can also be gradually reduced or gradually increased and then gradually reduced as the thickness of the first buffer layer 203 increases. In other specific embodiments, in the process of forming the first buffer layer 203, the deposition process parameters are kept unchanged so that the atomic concentrations of each element in the first buffer layer 203 remain consistent at different thickness positions.

[0057] In order to further enhance the adhesion between the first buffer layer 203 and the first bonding layer 201, the process parameters can be gradually adjusted during the formation of the first bonding layer 201, so that the component concentration in the first bonding layer 201 gradually changes, so that the material components on both sides of the interface between the first bonding layer 201 and the first buffer layer 203 are close. In a specific embodiment, during the formation of the first bonding layer 201, as the thickness of the first bonding layer 201 increases, the atomic concentration of C is gradually increased as the thickness of the first bonding layer 201 increases by adjusting the parameters of the deposition process. In other specific embodiments, the atomic concentration of C can also be gradually decreased as the thickness of the first bonding layer 201 increases, or first gradually increases and then gradually decreases. In other specific embodiments, during the formation of the first bonding layer 201, the deposition process parameters are kept unchanged, so that the elements in the first bonding layer 201 remain consistent at different thickness positions.

[0058] In order to make the first adhesion layer 202 and the first buffer layer 203 have a high density at each thickness, in order to reduce the H in the first adhesion layer 202 as much as possible during the ion bombardment process of forming the first adhesion layer 202, so that the density of the first adhesion layer 202 at each thickness is improved, the thickness of the first adhesion layer 202 cannot be too large. In a specific embodiment, the thickness of the first adhesion layer 202 is The thickness of the first buffer layer 203 is

[0059] In some specific embodiments, the thickness of the first bonding layer 201 is greater than the thickness of the first adhesion layer 202 and the first buffer layer 203, so as to ensure that the first bonding layer 201 has sufficient bonding thickness when bonding the first bonding layer 201 to other bonding layers. In a specific embodiment, the thickness of the first bonding layer 201 is greater than

[0060] In other specific embodiments, the first bonding layer 201 may also include two or more stacked sub-bonding layers. The materials of different sub-bonding layers may be the same or different.

[0061] The semiconductor structure of the above-mentioned specific embodiment has a first adhesion layer and a first buffer layer between the first substrate and the first bonding layer, and the density of the first adhesion layer and the first buffer layer is greater than the density of the first bonding layer, thereby improving the adhesion between the first adhesion layer and the first substrate, and the adhesion between the first buffer layer and the first bonding layer; and the first buffer layer and the first adhesion layer both have a high density, and the first buffer layer and the first adhesion layer also have a high adhesion, which can avoid the semiconductor structure from breaking and other problems. And the first bonding layer can also have a strong bonding force on the bonding surface after bonding, which can block the diffusion of metal materials at the bonding interface, thereby improving the performance of the formed semiconductor structure.

[0062] Please refer to Figure 3 In another specific embodiment, it also includes: providing a second substrate 300; forming a second adhesion layer 402 on the surface of the second substrate 300, a second buffer layer 403 located on the surface of the second adhesion layer 402, and a second bonding layer 401 located on the surface of the second buffer layer 403.

[0063] The second base 300 includes a second semiconductor substrate 301 and a second device layer 302 located on the surface of the second semiconductor substrate 201 .

[0064] The material of the second adhesion layer 402 is a dielectric material having a density greater than that of the second bonding layer 401. The material of the second adhesion layer 402 may be at least one of silicon nitride, silicon oxynitride and silicon oxide. Based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second adhesion layer 402 may also contain at least one of elements such as O, H, P, and F.

[0065] The material of the second buffer layer 403 is a dielectric material having a density greater than that of the second buffer layer 403. The material of the second buffer layer 403 is a dielectric material containing the C element. In a specific embodiment, the second buffer layer 403 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second buffer layer 403 may also contain at least one of Si, N, O, H, P, F and the like.

[0066] The material of the second bonding layer 401 is a dielectric material containing C element, and the atomic concentration of C in the first bonding layer 201 is greater than the atomic concentration of C in the first buffer layer 203. In one specific embodiment, the second bonding layer 401 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second bonding layer 401 can also be doped with at least one of the elements Si, N, O, H, P, F, etc. If the atomic concentration of C in the material layer is too high, the adhesion with other material layers will be reduced. The atomic concentration of C in the second buffer layer 403 is less than the atomic concentration of C in the second bonding layer 401. Compared with directly forming the second bonding layer 401 on the surface of the second adhesion layer 402, the adhesion between the second buffer layer 403 and the second adhesion layer 402 is higher.

[0067] The second adhesion layer 402, the second buffer layer 403 and the second bonding layer 401 are sequentially formed on the surface of the second device layer 302 by chemical vapor deposition process. For the specific materials, structures and formation methods of the second adhesion layer 402, the second buffer layer 403 and the second bonding layer 401, please refer to the description of the first adhesion layer 202, the first buffer layer 203 and the first bonding layer 201 in the above specific embodiment, which will not be repeated here. In a specific embodiment, the second adhesion layer 402 has the same material, structure and formation method as the first adhesion layer 202; the second buffer layer 403 has the same material, structure and formation method as the first buffer layer 203, and the second bonding layer 401 has the same material, structure and formation method as the first bonding layer 201.

[0068] In a specific embodiment, the thickness of the second adhesion layer 402 is The thickness of the second buffer layer 403 is The thickness of the second bonding layer 401 is greater than

[0069] Please refer to Figure 4 , the second bonding layer 401 is bonded and fixed relative to the surface of the first bonding layer 201.

[0070] The second bonding layer 401 and the first bonding layer 201 both contain C, and part of the C exists in the form of -CH3, which is more easily oxidized to -OH and forms Si-O bonds during the bonding process, so that more silicon-oxygen bonds can be formed on the bonding interface, thereby forming a stronger bonding force. In a specific embodiment, the bonding force between the second bonding layer 401 and the first bonding layer 201 is greater than 2J / M 2 In the prior art, a bonding layer without C is used for bonding, and the bonding force is usually less than 1.5 J / M 2 .

[0071] In a specific embodiment, the first substrate 100 is a substrate formed with a 3D NAND memory structure, and the second substrate 200 is a substrate formed with a peripheral circuit.

[0072] In other specific embodiments, the above-mentioned adhesion layer and bonding layer may be formed on both side surfaces of the substrate to achieve multi-layer bonding.

[0073] Please refer to Figure 5 In another specific embodiment, it also includes: forming a first bonding pad 501 that penetrates the first bonding layer 201, the first buffer layer 203 and the first adhesion layer 202; forming a second bonding pad 502 that penetrates the second bonding layer 401, the second buffer layer 403 and the second adhesion layer 402; while the surface of the second bonding layer 401 is bonded and fixed relative to the surface of the first bonding layer 201, the first bonding pad 501 is bonded and connected relative to the second bonding pad 502.

[0074] The first bonding pad 501 and the second bonding pad 502 may be connected to semiconductor devices and metal interconnection layers in the first device layer 102 and the second device layer 302 , respectively.

[0075] The method for forming the first bonding pad 501 includes: patterning the first bonding layer 201, the first buffer layer 203 and the first adhesion layer 202 to form an opening penetrating the first bonding layer 201, the first buffer layer 203 and the first adhesion layer 202; filling the opening with a metal material and flattening the opening to form the first bonding pad 501 that fills the opening. The second bonding pad 502 is formed in the second bonding layer 401, the second buffer layer 403 and the second adhesion layer 402 by the same method. The first bonding pad 501 is bonded to the second bonding pad 502 to achieve electrical connection between the semiconductor devices in the first device layer 102 and the second device layer 302.

[0076] The materials of the first bonding pad 501 and the second bonding pad 502 can be metal materials such as Cu, W, etc. The first bonding layer 201 and the second bonding layer 401 contain C, which can effectively prevent the materials of the first bonding pad 501 and the second bonding pad 502 from diffusing at the bonding interface, thereby improving the performance of the semiconductor structure.

[0077] In the above specific implementation manner, an adhesion layer is formed on the surface of the substrate, a buffer layer is formed on the surface of the adhesion layer, and then a bonding layer is formed on the surface of the buffer layer. The density of the adhesion layer and the buffer layer is greater than the density of the bonding layer, thereby improving the adhesion between the adhesion layer, the buffer layer and the substrate, and the bonding layer. After bonding, the bonding layer can also have a strong bonding force on the bonding surface, which can block the diffusion of metal materials at the bonding interface, thereby improving the performance of the formed semiconductor structure.

[0078] The semiconductor structure forming method of the above specific embodiment is also used for bonding multiple substrates.

[0079] Please refer to Figure 6 In a specific embodiment of the present invention, a third substrate 600 is provided, and a third adhesion layer 702, a third buffer layer 703 and a third bonding layer 701 are sequentially formed on a surface of one side of the third substrate 600, and a fourth adhesion layer 802, a fourth buffer layer 803 and a fourth bonding layer 801 are sequentially formed on an opposite surface of the other side; the third bonding layer 701 is bonded and fixed to the surface of the first bonding layer 201, and the fourth bonding layer 801 is bonded and fixed to the surface of the second bonding layer 401, so as to form a three-layer bonding structure.

[0080] For the materials, structure and formation method of the third adhesion layer 702 and the fourth adhesion layer 802, the materials, structure and formation method of the third buffer layer 703 and the fourth buffer layer 803, and the materials, structure and formation method of the third bonding layer 701 and the fourth bonding layer 801, please refer to the above-mentioned specific implementation methods, and the materials, structure and formation method of the first adhesion layer 202, the first buffer layer 203 and the first bonding layer 201, which will not be repeated here.

[0081] In this specific embodiment, the method for forming the semiconductor structure also includes: forming a third bonding pad 704 that penetrates the third bonding layer 701, the third buffer layer 703 and the third adhesion layer 702, forming a fourth bonding pad 804 that penetrates the fourth bonding layer 801, the fourth buffer layer 803 and the fourth adhesion layer 802, bonding the third bonding pad 704 to the first bonding pad 501, and bonding the fourth bonding pad 804 to the second bonding pad 502.

[0082] In other specific implementations, the above method may also be used to form a bonding structure with more than four layers.

[0083] It should be noted that in the technical solution of the present invention, the type of semiconductor devices in each substrate in the semiconductor structure should not be limited to the given embodiment. In addition to 3D NAND, it can be a CMOS circuit, a CIS circuit, a TFT circuit, etc.

[0084] A specific embodiment of the present invention further provides a semiconductor structure.

[0085] Please refer to Figure 2 , which is a schematic structural diagram of a semiconductor structure according to a specific embodiment of the present invention.

[0086] The semiconductor structure includes: a first substrate 100 ; a first adhesion layer 202 located on the surface of the first substrate 100 ; a first buffer layer 203 located on the surface of the first adhesion layer 202 ; and a first bonding layer 201 located on the surface of the first buffer layer 203 .

[0087] The first base 100 includes a first semiconductor substrate 101 and a first device layer 102 formed on a surface of the first semiconductor substrate 101 .

[0088] The first semiconductor substrate 101 may be a single crystal silicon substrate, a Ge substrate, a SiGe substrate, a SOI or a GOI, etc.; according to the actual needs of the device, a suitable first semiconductor substrate 101 may be selected, which is not limited here. In this specific embodiment, the first semiconductor substrate 101 is a single crystal silicon wafer.

[0089] The first device layer 102 includes semiconductor devices formed on the semiconductor substrate 101, metal interconnect structures connecting the semiconductor devices, a dielectric layer covering the semiconductor devices and the metal interconnect structures, etc. The first device layer 102 can be a multi-layer or single-layer structure. In a specific embodiment, the first device layer 102 includes a dielectric layer and a 3D NAND structure formed in the dielectric layer.

[0090] The material of the first adhesion layer 202 is a dielectric material with a density greater than that of the first bonding layer 201. The material of the first adhesion layer 202 may be at least one of silicon nitride, silicon oxynitride and silicon oxide. Based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first adhesion layer 202 may also be doped with at least one of elements such as O, H, P, and F. In a specific embodiment, the first adhesion layer 202 is SiN with high density.

[0091] The material of the first buffer layer 203 is a dielectric material containing C element. In a specific embodiment, the first buffer layer 203 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first buffer layer 203 can also be doped with at least one of the elements Si, N, O, H, P, F, etc. In this specific embodiment, the density of the first buffer layer 203 is greater than the density of the first bonding layer 201, and the density of the first buffer layer 203 is close to or the same as the density of the first adhesion layer 202. The material of the first buffer layer 203 can be carbon-doped silicon nitride, carbon-doped silicon oxide, nitrogen-doped carbon oxide, etc. Since the density of the first buffer layer 203 is relatively high, the density of chemical bonds on the interface with the first adhesion layer 202 is relatively high, so it has high adhesion with the first adhesion layer 202.

[0092] The material of the first bonding layer 201 is a dielectric material containing C element. The atomic concentration of C in the first bonding layer 201 is greater than the atomic concentration of C in the first buffer layer 203. In one specific embodiment, the first bonding layer 201 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the first bonding layer 201 can also be doped with at least one of the elements such as Si, N, O, H, P, and F. The material of the first bonding layer 201 can be carbon-doped silicon nitride, carbon-doped silicon oxide, nitrogen-doped carbon oxide, etc. The composition of the first bonding layer 201 is close to or the same as that of the first buffer layer 203. Therefore, when the first bonding layer 201 is located on the surface of the first buffer layer 203, the first bonding layer 201 and the first buffer layer 203 can have a higher adhesion. If the atomic concentration of C in the material layer is too high, the adhesion with other material layers will decrease. The atomic concentration of C in the first buffer layer 203 is lower than that in the first bonding layer 201 . Compared with forming the first bonding layer 201 directly on the surface of the first adhesion layer 202 , the adhesion between the first buffer layer 203 and the first adhesion layer 202 is higher.

[0093] The C in the first bonding layer 201 can effectively improve the bonding force between the first bonding layer 201 and other bonding layers during the bonding process. The higher the C concentration, the greater the bonding force generated when bonding with other bonding layers. In a specific embodiment, the atomic concentration of C in the first bonding layer 201 is greater than 35%.

[0094] The atomic concentration of C in the first buffer layer 203 is less than that in the first bonding layer 201, so that the material structure of the first buffer layer 203 is closer to that of the first adhesion layer 202. In a specific embodiment, the atomic concentration of C in the first buffer layer 203 is 0-50%.

[0095] Since the first bonding layer 201 contains a higher concentration of C element, the density of the first bonding layer 201 is relatively low. In the specific embodiment of the present application, a first adhesion layer 202 and a first buffer layer 203 with higher density are formed between the first bonding layer 201 and the first substrate 100, and the atomic concentration of C in the first buffer layer 203 is lower than the atomic concentration of C in the first bonding layer 201, which can improve the adhesion between the layers.

[0096] Since the adhesion between different material layers is related to the material components on both sides of the interface, the closer the material components are, the stronger the adhesion is. In order to further enhance the adhesion between the first adhesion layer 202 and the first device layer 102, the component concentration in the first adhesion layer 202 gradually changes with the thickness, so that the material components on both sides of the interface between the first device layer 102 and the first adhesion layer 202 are close. In one specific embodiment, the atomic concentration of Si in the first adhesion layer 202 gradually changes with the increase of the thickness of the first adhesion layer 202. In other specific embodiments, depending on the different surface materials of the first device layer 102, the concentration of other components in the first adhesion layer 202 may also change with the thickness. In other specific embodiments, the atomic concentration of each element in the first adhesion layer 202 may also be kept consistent at different thickness positions.

[0097] In order to further enhance the adhesion between the first adhesion layer 202 and the first buffer layer 203, the material components on both sides of the interface between the first buffer layer 203 and the first adhesion layer 202 are close. In one specific embodiment, the atomic concentration of C in the first buffer layer 203 gradually increases with the thickness of the first buffer layer 203. In other specific embodiments, the atomic concentration of C in the first buffer layer 203 gradually decreases or first gradually increases and then gradually decreases with the thickness of the first buffer layer 203. In other specific embodiments, the atomic concentrations of each element in the first buffer layer 203 remain consistent at different thickness positions.

[0098] In order to further enhance the adhesion between the first buffer layer 203 and the first bonding layer 201, the component concentration in the first bonding layer 201 may also gradually change with the thickness, so that the material components on both sides of the interface between the first bonding layer 201 and the first buffer layer 203 are close. In one specific embodiment, as the thickness of the first bonding layer 201 increases, the C atomic concentration in the first bonding layer 201 gradually increases with the increase of the thickness of the first bonding layer 201. In other specific embodiments, the atomic concentration of C in the first bonding layer 201 gradually decreases with the increase of the thickness of the first bonding layer 201, or first gradually increases and then gradually decreases. In other specific embodiments, the elements in the first bonding layer 201 remain consistent at different thickness positions, and have a uniformly distributed atomic concentration.

[0099] In order to make the first adhesion layer 202 and the first buffer layer 203 have a high density at each thickness, the thickness of the first adhesion layer 202 and the first buffer layer 203 cannot be too large. In a specific embodiment, the thickness of the first adhesion layer 202 is The thickness of the first buffer layer 203 is

[0100] In some specific embodiments, the thickness of the first bonding layer 201 is greater than the thickness of the first adhesion layer 202 and the first buffer layer 203, so as to ensure that the first bonding layer 201 has sufficient bonding thickness when bonding the first bonding layer 201 to other bonding layers. In a specific embodiment, the thickness of the first bonding layer 201 is greater than

[0101] In other specific embodiments, the first bonding layer 201 may also include two or more stacked sub-bonding layers, and the materials of different sub-bonding layers may be the same or different.

[0102] Please refer to Figure 4 , is a schematic diagram of a semiconductor structure according to another specific embodiment of the present invention.

[0103] In this specific embodiment, the semiconductor structure also includes: a second substrate 300, a second adhesion layer 402, a second buffer layer 403 located on the surface of the second adhesion layer 402, and a second bonding layer 401 located on the surface of the second buffer layer 403 are formed on the surface of the second substrate 300; the second bonding layer 401 is bonded and fixed relative to the surface of the first bonding layer 201.

[0104] The second base 300 includes a second semiconductor substrate 301 and a second device layer 302 located on the surface of the second semiconductor substrate 201 .

[0105] The material of the second adhesion layer 402 is a dielectric material with a density greater than that of the second bonding layer 401. The material of the second adhesion layer 402 may be at least one of silicon nitride, silicon oxynitride and silicon oxide. Based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second adhesion layer 402 may also be doped with at least one of elements such as O, H, P, and F.

[0106] The material of the second buffer layer 403 is a dielectric material having a density greater than that of the second buffer layer 403. The material of the second buffer layer 403 is a dielectric material containing the C element. In a specific embodiment, the second buffer layer 403 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second buffer layer 403 may also be doped with at least one of the elements Si, N, O, H, P, F, etc.

[0107] The material of the second bonding layer 401 is a dielectric material containing C element. The atomic concentration of C in the first bonding layer 201 is greater than the atomic concentration of C in the first buffer layer 203. In a specific embodiment, the second bonding layer 401 mainly contains Si, N and C. In other specific embodiments, based on the reaction gas used in the chemical vapor deposition process and the requirements of specific products, the second bonding layer 401 can also be doped with at least one of Si, N, O, H, P, F and other elements. The atomic concentration of C in the second buffer layer 403 is less than the atomic concentration of C in the second bonding layer 401, so that the second buffer layer 403 and the second adhesion layer 402 have a higher adhesion force.

[0108] The specific materials and structures of the second adhesion layer 402, the second buffer layer 403 and the second bonding layer 401 refer to the description of the first adhesion layer 202, the first buffer layer 203 and the first bonding layer 201 in the above specific embodiment, which will not be repeated here. In one specific embodiment, the second adhesion layer 402 has the same material and structure as the first adhesion layer 202; the second buffer layer 403 has the same material and structure as the first buffer layer 203; the second bonding layer 401 has the same material and structure as the first bonding layer 201. In one specific embodiment, the thickness of the second adhesion layer 402 is The thickness of the second bonding layer 401 is greater than

[0109] The second bonding layer 401 and the first bonding layer 201 both contain C, so that more silicon-oxygen bonds are formed on the bonding interface, and a stronger bonding force is obtained. In a specific embodiment, the bonding force between the second bonding layer 401 and the first bonding layer 201 is greater than 1.7 J / M2 .

[0110] In other specific embodiments, the semiconductor structure may include more than three substrates, and adjacent substrates are bonded to each other through the adhesion layer and the bonding layer in the specific embodiments of the present invention.

[0111] Please refer to Figure 5 , is a schematic structural diagram of a semiconductor structure according to another specific embodiment of the invention.

[0112] In this specific embodiment, the semiconductor structure also includes: a first bonding pad 501 that penetrates the first bonding layer 201, the first buffer layer 203 and the first adhesion layer 202; a second bonding pad 502 that penetrates the second bonding layer 401, the second buffer layer 403 and the second adhesion layer 402; the surface of the second bonding layer 401 is bonded and fixed relative to the surface of the first bonding layer 201, and the first bonding pad 501 is bonded and connected relative to the second bonding pad 502.

[0113] The first bonding pad 501 and the second bonding pad 502 may be connected to semiconductor devices and metal interconnection layers in the first device layer 102 and the second device layer 302 , respectively.

[0114] The materials of the first bonding pad 501 and the second bonding pad 502 can be metal materials such as Cu, W, etc. The first bonding layer 201 and the second bonding layer 401 contain C, which can effectively prevent the materials of the first bonding pad 501 and the second bonding pad 502 from diffusing at the bonding interface, thereby improving the performance of the semiconductor structure.

[0115] Please refer to Figure 6 In a specific embodiment of the present invention, the semiconductor structure further includes a third substrate 600, a third adhesion layer 702 located on one side surface of the third substrate 600, a third buffer layer 703 located on the surface of the third adhesion layer 702, and a third bonding layer 701 located on the surface of the third buffer layer 703, a fourth adhesion layer 802 located on the opposite surface of the other side of the third substrate 600, a fourth buffer layer 803 located on the surface of the fourth adhesion layer 802, and a fourth bonding layer 801 located on the surface of the fourth buffer layer 803; the third bonding layer 701 is bonded and fixed to the surface of the first bonding layer 201, and the fourth bonding layer 801 is bonded and fixed to the surface of the second bonding layer 401, forming a three-layer bonding structure.

[0116] For the materials and structures of the third adhesion layer 702 and the fourth adhesion layer 802, the materials and structures of the third buffer layer 703 and the fourth buffer layer 803, and the materials and structures of the third bonding layer 701 and the fourth bonding layer 801, please refer to the description of the materials and structures of the first adhesion layer 202, the first buffer layer 203 and the first bonding layer 201 in the above specific implementation manner, and no further details will be given here.

[0117] In this specific embodiment, the semiconductor structure also includes: a third bonding pad 704 penetrating the third bonding layer 701, the third buffer layer 703 and the third adhesion layer 702, and a fourth bonding pad 804 penetrating the fourth bonding layer 801, the fourth buffer layer 803 and the fourth adhesion layer 802, the third bonding pad 704 is bonded to the first bonding pad 501, and the fourth bonding pad 804 is bonded to the second bonding pad 502.

[0118] In other specific implementations, the semiconductor structure may also be a bonding structure with more than four layers.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A semiconductor structure, characterized in that: include: first base; A first adhesion layer located on the surface of the first substrate, wherein the material of the first adhesion layer comprises Si and N; A first buffer layer located on the surface of the first adhesion layer, wherein the material of the first buffer layer is a dielectric material containing Si, N, and C elements; a first bonding layer located on the surface of the first buffer layer, wherein the first adhesion layer and the first buffer layer have densities greater than that of the first bonding layer, and the material of the first bonding layer is a dielectric material containing Si, N, and C elements; A second substrate, a second adhesion layer is formed on the surface of the second substrate, a second buffer layer is located on the surface of the second adhesion layer, and a second bonding layer is located on the surface of the second buffer layer; the density of the second adhesion layer and the second buffer layer is greater than the density of the second bonding layer; the second bonding layer is made of the same material as the first bonding layer, the second buffer layer is made of the same material as the first buffer layer, the second adhesion layer is made of the same material as the first adhesion layer, and the second bonding layer is bonded and fixed relative to the surface of the first bonding layer.

2. The semiconductor structure according to claim 1, characterized in that: The atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer.

3. The semiconductor structure according to claim 2, characterized in that: The atomic concentration of C in the first bonding layer is greater than 35%, and the atomic concentration of C in the first buffer layer is 0-50%.

4. The semiconductor structure according to claim 2, characterized in that: In the first bonding layer, the atomic concentration of C increases as the thickness of the first bonding layer increases; in the first buffer layer, the atomic concentration of C increases as the thickness of the first buffer layer increases.

5. The semiconductor structure according to claim 1, characterized in that: The material of the first adhesion layer includes at least one of silicon nitride, silicon oxynitride and silicon oxide.

6. The semiconductor structure according to claim 1, characterized in that The thickness of the first adhesion layer is The thickness of the first buffer layer is 7. The semiconductor structure according to claim 1, characterized in that: The material components on both sides of the interface between the first bonding layer and the first buffer layer are substantially the same.

8. The semiconductor structure according to claim 1, characterized in that: Also includes: a first bonding pad extending through the first bonding layer, the first buffer layer, and the first adhesion layer; A second bonding pad runs through the second bonding layer, the second buffer layer and the second adhesion layer; the first bonding pad is bonded to the second bonding pad.

9. A semiconductor structure, characterized in that: include: first base; A first adhesion layer located on the surface of the first substrate, wherein the material of the first adhesion layer comprises Si and N; a first buffer layer located on the surface of the first adhesion layer, wherein the material of the first buffer layer is a dielectric material containing Si, N, and C elements, and the atomic concentration of C in the first buffer layer increases with the increase of the thickness of the first buffer layer; a first bonding layer located on the surface of the first buffer layer, wherein the material of the first bonding layer is a dielectric material containing Si, N, and C elements, the atomic concentration of C in the first bonding layer increases with the thickness of the first bonding layer, and the density of the first adhesion layer and the first buffer layer is greater than the density of the first bonding layer; A second substrate, a second adhesion layer is formed on the surface of the second substrate, a second buffer layer is located on the surface of the second adhesion layer, and a second bonding layer is located on the surface of the second buffer layer; the density of the second adhesion layer and the second buffer layer is greater than the density of the second bonding layer; the second bonding layer is made of the same material as the first bonding layer, the second buffer layer is made of the same material as the first buffer layer, the second adhesion layer is made of the same material as the first adhesion layer, and the second bonding layer is bonded and fixed relative to the surface of the first bonding layer.

10. A semiconductor structure, characterized in that: include: first base; A first adhesion layer located on the surface of the first substrate, wherein the material of the first adhesion layer comprises Si and N; A first buffer layer located on the surface of the first adhesion layer, wherein the material of the first buffer layer is a dielectric material containing Si, N, and C elements; a first bonding layer located on the surface of the first buffer layer, wherein the material of the first bonding layer is a dielectric material containing Si, N, and C elements; wherein the atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer; A second substrate, a second adhesion layer is formed on the surface of the second substrate, a second buffer layer is located on the surface of the second adhesion layer, and a second bonding layer is located on the surface of the second buffer layer; the second bonding layer is made of the same material as the first bonding layer, the second buffer layer is made of the same material as the first buffer layer, the second adhesion layer is made of the same material as the first adhesion layer, and the second bonding layer is bonded and fixed relative to the surface of the first bonding layer.

11. The semiconductor structure according to claim 10, characterized in that: Atomic concentrations of H in the first adhesion layer and the first buffer layer are both lower than atomic concentrations of H in the first bonding layer.

12. A method for forming a semiconductor structure, characterized in that: include: providing a first substrate; forming a first adhesion layer on the surface of the first substrate, and performing plasma bombardment on the first adhesion layer to reduce the atomic concentration of H, wherein the material of the first adhesion layer comprises Si and N; forming a first buffer layer on the surface of the first adhesion layer, wherein the material of the first buffer layer is a dielectric material containing Si, N, and C elements; forming a first bonding layer on the surface of the first buffer layer, wherein the material of the first bonding layer is a dielectric material containing Si, N, and C elements; providing a second substrate; forming a second adhesion layer, a second buffer layer located on the surface of the second adhesion layer, and a second bonding layer located on the surface of the second buffer layer on the surface of the second substrate, wherein the second bonding layer is made of the same material as the first bonding layer, the second buffer layer is made of the same material as the first buffer layer, and the second adhesion layer is made of the same material as the first adhesion layer; The second bonding layer surface is bonded and fixed relative to the first bonding layer surface.

13. The method for forming a semiconductor structure according to claim 12, wherein: Atomic concentrations of H in the first adhesion layer and the first buffer layer are both lower than atomic concentrations of H in the first bonding layer.

14. The method for forming a semiconductor structure according to claim 12, wherein: Before the plasma bombardment, the first adhesion layer contains H bonds; in the plasma bombardment step, N-containing plasma is used for bombardment to reduce the H bonds in the first adhesion layer.

15. The method for forming a semiconductor structure according to claim 12, wherein: The atomic concentration of C in the first bonding layer is greater than the atomic concentration of C in the first buffer layer.

16. The method for forming a semiconductor structure according to claim 12, wherein: The material of the first adhesion layer includes at least one of silicon nitride, silicon oxynitride and silicon oxide.

17. The method for forming a semiconductor structure according to claim 12, wherein: The thickness of the first adhesion layer is The thickness of the first buffer layer is 18. The method for forming a semiconductor structure according to claim 12, wherein: The atomic concentration of C in the first bonding layer is greater than 35%, and the material components on both sides of the interface between the first bonding layer and the first buffer layer are substantially the same.

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