Preparation method of composite film for reducing wafer warping, composite film and application

Abstract

The invention belongs to the technical field of semiconductor preparation, and particularly relates to a preparation method of a composite film for reducing wafer warping, the composite film and application. The method comprises the following steps: S1, bonding a first piezoelectric wafer and a second piezoelectric wafer to obtain a first bonding body; s2, performing double-sided ion implantation on the first bonding body to obtain a wafer implantation sheet which sequentially comprises a first thin film layer, a first implantation layer, a first residual material layer, a second residual material layer, a second implantation layer and a second thin film layer; s3, bonding the first thin film layer with the first supporting substrate, and bonding the second thin film layer with the second supporting substrate to obtain a second bonding body; and S4, heating and annealing the second bonding body to obtain a first composite film, a second composite film and a third bonding body. According to the invention, ion implantation is carried out on the first bonding body formed by the first piezoelectric wafer and the second piezoelectric wafer, so that the warping degree of the wafers is greatly reduced; two composite films can be obtained at the same time, the production period is shortened, and the process cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor preparation, and in particular relates to a composite film preparation method for reducing wafer warping, the composite film and applications. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The rapidly growing amount of mobile data has put forward higher requirements for data transmission. In order to achieve fast data transmission and chip integration, the development of radio frequency wave filters shows a trend of "high frequency, high power, and miniaturization". There are two main types of radio frequency filters: surface acoustic wave filters and bulk acoustic wave filters. Traditional acoustic filters based on single crystal materials are difficult to meet the needs of new 5G communication technologies. In recent years, high-performance radio frequency filters based on piezoelectric single crystal films have received widespread attention in the industry and have been increasingly widely used. Correspondingly, the preparation technology of piezoelectric composite films is also developing in the direction of high efficiency, low cost, and high quality.

[0004] At present, ion beam stripping technology is usually used to prepare composite films. First, the piezoelectric wafer is treated with ion implantation to form a thin film layer, a residual layer, and an implantation layer located between the thin film layer and the residual layer. Then, the surface of the thin film layer of the piezoelectric wafer is contacted with the polished surface of the supporting substrate to form a bond. Finally, the bond is heated for annealing. During the annealing process, the ions in the implantation layer will form gas under the thermal effect, thereby generating bubbles between the implantation layers and connecting them to each other, and finally the residual layer and the thin film layer are separated instantly to obtain a composite film.

[0005] However, during the ion implantation process, the injected ions collide with the atoms in the piezoelectric wafer and lose energy. The energy-depleted ions will stop at a certain position in the piezoelectric wafer. The implantation process will produce a large amount of thermal effects and thermal stresses, and the piezoelectric material has anisotropy, which will cause the piezoelectric wafer to warp significantly after the implantation, which will have an adverse effect on the subsequent bonding, annealing and other process processes, and will easily cause the composite film to burst, reduce the production yield, and increase the production cost of the composite film. CN117597008A pre-bonds the piezoelectric wafer with the supporting substrate to obtain a rigid bonding structure, which can effectively suppress the uneven thermal expansion deformation of the piezoelectric wafer during the ion implantation process, and greatly improve the wafer warping problem faced in the process of preparing piezoelectric single crystal thin films. Although the patent can be recycled after the peeling residue is processed, and the thicker piezoelectric single crystal thin film can also be thinned, only one piezoelectric single crystal thin film can be obtained in one process, and the residue processing is cumbersome. Although CN118866806A overcomes the stress deformation problem of the silicon substrate caused by single-sided ion implantation through double-sided ion implantation, it is necessary to further deposit a leveling layer to ensure the bonding quality when the silicon substrate and the silicon carbide substrate are bonded, thereby achieving two thermal stresses of equal size, opposite direction and mutual offset at the two bonding interfaces. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the present invention provides a composite film preparation method and composite film and application for reducing wafer warpage. The present invention greatly reduces the degree of wafer warpage by performing ion implantation on a first bonded body formed by a first piezoelectric wafer and a second piezoelectric wafer; two composite films, the first composite film and the second composite film, can be obtained at the same time, shortening the production cycle and reducing the process cost; and the third bonded body obtained after thermal separation is recycled to improve the material utilization rate.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a composite film for reducing wafer warpage, comprising the following steps:

[0009] S1, bonding a first piezoelectric wafer and a second piezoelectric wafer to obtain a first bonding body;

[0010] S2, performing double-sided ion implantation on the first bonding body to obtain an implanted wafer including a first thin film layer, a first implantation layer, a first residual layer, a second residual layer, a second implantation layer and a second thin film layer in sequence;

[0011] S3, bonding the first film layer to the first supporting substrate, and bonding the second film layer to the second supporting substrate, to obtain a second bonded body;

[0012] S4, heating and annealing the second bonding body to obtain a first composite film including a first supporting substrate and a first film layer, a second composite film including a second supporting substrate and a second film layer, and a third bonding body including a first residual substance layer and a second residual substance layer.

[0013] Preferably, the materials of the first piezoelectric wafer and the second piezoelectric wafer are the same or different, including at least one of lithium niobate, lithium tantalate, quartz, lithium tetraborate and lanthanum gallium silicate; the thicknesses of the first piezoelectric wafer and the second piezoelectric wafer are the same or different, and are 0.2 to 1 mm; the bonding surfaces of the first piezoelectric wafer and the second piezoelectric wafer have the same polarity.

[0014] Preferably, the ions implanted include at least one of hydrogen ions and helium ions, with an energy of 50 to 500 KeV and a dose of 3×10 15 ~5×10 18 ions / cm 2 .

[0015] Preferably, the thickness of the first thin film layer and the second thin film layer are the same or different, and are 50-1000 nm.

[0016] Preferably, the materials of the first support substrate and the second support substrate are the same or different, including at least one of sapphire, silicon, silicon carbide, quartz, diamond, gallium nitride and gallium arsenide; the thickness of the first support substrate and the second support substrate are the same or different, and are 0.2 to 1 mm.

[0017] Preferably, the diameters of the first support substrate, the second support substrate, the first piezoelectric wafer and the second piezoelectric wafer are the same, which is 4 to 12 inches.

[0018] Preferably, the heating annealing temperature is 80° C. to 800° C., and the time is 0.5 to 60 hours.

[0019] Preferably, the method further comprises the following steps:

[0020] S5. Use the third bonding body as the first bonding body and repeat steps S2 to S4.

[0021] In a second aspect, the present invention provides a composite film obtained by the composite film preparation method as described in the first aspect.

[0022] In a third aspect, the present invention provides use of the composite film as described in the second aspect in preparing a semiconductor device including a radio frequency filter.

[0023] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0024] The present invention bonds the first piezoelectric wafer to the second piezoelectric wafer in advance to obtain a first bonding body of the bonding structure, and utilizes the bonding interface to relieve the pressure generated by ion implantation, which can effectively improve the thermal stress warping problem of the piezoelectric wafer during the ion implantation process, improve the yield of the piezoelectric single crystal film, and reduce the production cost of the composite film.

[0025] The present invention performs double-sided injection on the first bonding body formed by the first piezoelectric wafer and the second piezoelectric wafer, and can simultaneously obtain two composite films, a first composite film and a second composite film, after annealing and peeling. The first composite film and the second composite film can be selected with different thicknesses and different materials as needed, which shortens the production cycle and reduces the process cost, and can improve the production efficiency of the piezoelectric single crystal film.

[0026] The present invention recycles the third bonded body obtained after thermal separation, thereby improving material utilization and reducing emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 A schematic diagram of the process of the composite film preparation method for reducing wafer warpage of the present invention;

[0029] Figure 2 A schematic diagram of the structural flow of a composite film preparation method for reducing wafer warpage according to the present invention;

[0030] Figure 3 A schematic diagram of a process for reducing wafer warpage by reusing the third bonding body according to the present invention;

[0031] Figure 4 A schematic structural flow diagram of a method for preparing a composite thin film for reducing wafer warpage by repeatedly utilizing a third bonding body according to the present invention;

[0032] In the accompanying drawings, the numbers correspond to: 100-first bonding body, 1001-first piezoelectric wafer, 1002-second piezoelectric wafer, 110-wafer injection piece, 1101-first thin film layer, 1102-first injection layer, 1103-first residual layer, 1104-second residual layer, 1105-second injection layer, 1106-second thin film layer, 120-first supporting substrate, 130-second supporting substrate, 140-second bonding body, 150-third bonding body. DETAILED DESCRIPTION

[0033] As described in the background of the present invention, the ion implantation process will generate a large amount of thermal effects and thermal stresses, and the piezoelectric material is anisotropic, which will cause the piezoelectric wafer to warp significantly after implantation. Although the prior art uses a rigid structure obtained by pre-bonding the piezoelectric wafer with a supporting substrate to suppress warping, only one piezoelectric single crystal film can be obtained in one process, and the handling of the remaining material is cumbersome.

[0034] In order to solve the above problems, the embodiments of the present invention provide a composite film preparation method for reducing wafer warpage, a composite film and an application.

[0035] Specifically, an embodiment of the present invention provides a method for preparing a composite film that reduces wafer warpage, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0036] S1, bonding the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 to obtain a first bonding body 100;

[0037] S2, performing double-sided ion implantation on the first bonding body 100 to obtain a wafer implantation sheet 110 which sequentially includes a first thin film layer 1101, a first implantation layer 1102, a first residual layer 1103, a second residual layer 1104, a second implantation layer 1105, and a second thin film layer 1106;

[0038] S3, bonding the first film layer 1101 to the first supporting substrate 120, and bonding the second film layer 1106 to the second supporting substrate 120, to obtain a second bonding body 140;

[0039] S4, heating and annealing the second bonding body 140 to obtain a first composite film including the first supporting substrate 120 and the first film layer 1101, a second composite film including the second supporting substrate 130 and the second film layer 1106, and a third bonding body 150 including the first residual layer 1103 and the second residual layer 1104.

[0040] The present invention does not specifically limit the bonding method, and any bonding method in the prior art can be used, such as bonding by surface activation to obtain a bonded body. The present invention does not specifically limit the surface activation method, and for example, plasma activation or chemical solution activation can be used. In an embodiment of the present invention, the two contacting bonding surfaces are cleaned before bonding to enhance the bonding effect. The present invention does not specifically limit the cleaning method, and it can be a chemical solution cleaning method.

[0041] In an embodiment of the present invention, the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 have polished surfaces.

[0042] In an embodiment of the present invention, the materials of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are the same or different, including at least one of lithium niobate, lithium tantalate, quartz, lithium tetraborate and lanthanum gallium silicate. In some embodiments of the present invention, the materials of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are both lithium niobate.

[0043] In an embodiment of the present invention, the thickness of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are the same or different, and are 0.2-1 mm. In some embodiments of the present invention, the thickness of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are the same.

[0044] In an embodiment of the present invention, the bonding surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 have the same polarity. In some embodiments of the present invention, the bonding surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 have positive polarity.

[0045] In an embodiment of the present invention, the ions implanted include at least one of hydrogen ions and helium ions, with an energy of 50 to 500 KeV and a dose of 3×10 15 ~5×10 18 ions / cm 2 In some embodiments of the present invention, the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are both lithium niobate wafers, and helium ions are implanted into both sides of the first bonding body 110. The implantation energy of the helium ions is 50 to 500 KeV, and the dosage is 5×10 15 ~3×10 17 ions / cm 2 .

[0046] In an embodiment of the present invention, the thickness of the first thin film layer 1101 and the second thin film layer 1106 are the same or different, and are 50 to 1000 nm. The injected ions are distributed in the first injection layer 1102 and the second injection layer 1105. The greater the energy of the ion injection, the greater the thickness of the prepared first thin film layer 1101 and the second thin film layer 1106; on the contrary, the smaller the energy of the ion injection, the smaller the thickness of the prepared first thin film layer 1101 and the second thin film layer 1106.

[0047] In an embodiment of the present invention, the first support substrate 120 and the second support substrate 130 are made of the same or different materials, including at least one of sapphire, silicon, silicon carbide, quartz, diamond, gallium nitride and gallium arsenide. In some embodiments of the present invention, the first support substrate 120 and the second support substrate 130 are both made of silicon carbide.

[0048] In an embodiment of the present invention, the thickness of the first support substrate 120 and the second support substrate 130 are the same or different, and are 0.2 to 1 mm. In some embodiments of the present invention, the thickness of the first support substrate 120 and the second support substrate 130 are both 0.5 mm. In some embodiments of the present invention, the thickness of the first support substrate 120 is 0.5 mm, and the thickness of the second support substrate 130 is 0.55 mm.

[0049] In the embodiment of the present invention, the diameters of the first support substrate 120 , the second support substrate 130 , the first piezoelectric wafer 1001 , and the second piezoelectric wafer 1002 are the same, which is 4 to 12 inches.

[0050] In an embodiment of the present invention, the temperature of the heating annealing is 80°C to 800°C, and the time is 0.5 to 60 hours. The heating annealing is to enhance the bonding strength of the bonding body on the one hand; on the other hand, bubbles are formed in the first injection layer 1102 and the second injection layer 1105 during the heating annealing process, such as hydrogen ions forming hydrogen gas, and the bubbles in the first injection layer 1102 and the second injection layer 1105 are connected together, and finally the first injection layer 1102 and the second injection layer 1105 are broken, separating the first residual layer 1103 from the first thin film layer 1101, and the second residual layer 1104 from the second thin film layer 1206.

[0051] In the embodiment of the present invention, the surface of the first film layer 1101 , the surface of the second film layer 1106 , and both sides of the third bonding body 150 are ground and polished.

[0052] In an embodiment of the present invention, the following steps are also included:

[0053] S5. Use the third bonding body as the first bonding body and repeat steps S2 to S4.

[0054] In some embodiments of the present invention, both sides of the third bonding body 150 are thinned.

[0055] The present invention does not limit the grinding, polishing, and thinning methods. For example, surface chemical mechanical polishing, corrosion, or ion etching may be used.

[0056] In an embodiment of the present invention, a composite film is provided, which is obtained by the composite film preparation method described above.

[0057] In an embodiment of the present invention, the present invention provides use of the above composite film in preparing a semiconductor device including a radio frequency filter.

[0058] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0059] Example 1

[0060] Two lithium tantalate polished wafers with a diameter of 4 inches and a thickness of 0.5 mm were cleaned at the semiconductor level to have clean surfaces, and were used as the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 respectively.

[0061] The positive polarity surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are directly contacted, and due to the action of the van der Waals force, the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are bonded together to obtain the first bonding body 100 .

[0062] Hydrogen ions are implanted on both sides of the first bonding body 100, with a dose of 5×10 16 ions / cm 2 The implantation energy is 200 KeV, forming a wafer implantation sheet 110 having a six-layer structure of a first thin film layer 1101, a first implantation layer 1102, a first residual layer 1103, a second residual layer 1104, a second implantation layer 1105 and a second thin film layer 1106. The surfaces of the first thin film layer 1101 and the second thin film layer 1106 of the wafer implantation sheet 110 are cleaned at the semiconductor level to obtain a clean surface, which is conducive to the next step of bonding.

[0063] Two single crystal silicon carbide wafers with a diameter of 4 inches and a thickness of 0.5 mm are cleaned at the semiconductor level to have clean surfaces, and are respectively used as the first support substrate 120 and the second support substrate 130. The first film layer 1101 is directly in contact with the first support substrate 120, and the second film layer 1106 is directly in contact with the second support substrate 120, and they are bonded to each other due to the van der Waals force, thereby obtaining a second bonded body 140.

[0064] The second bonding body 140 is subjected to heating annealing treatment at a temperature of 280° C. for 10 hours, so that the first film layer 1101 and the second film layer 1106 are separated from the first residual layer 1103 and the second residual layer 1104 respectively, and the first film layer 1101 and the second film layer 1106 are polished respectively, and at the same time, a first composite film including the first support substrate 120 and the first film layer 1101, a second composite film including the second support substrate 130 and the second film layer 1106, and a third bonding body 150 including the first residual layer 1103 and the second residual layer 1104 are obtained. At the same time, the third bonding body 150 is subjected to thinning and polishing treatment, and the above process is repeated as the first bonding body 100 to improve the utilization rate of the raw materials.

[0065] Example 2

[0066] Two polished lithium niobate wafers with a diameter of 6 inches and a thickness of 0.5 mm were cleaned at the semiconductor level to have clean surfaces, and were used as the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 respectively.

[0067] The positive polarity surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are directly contacted, and due to the action of the van der Waals force, the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are bonded together to obtain the first bonding body 100 .

[0068] Helium ions are implanted on both sides of the first bonding body 100, with a dose of 9×10 15 ions / cm 2 The implantation energy is 150 KeV, forming a wafer implantation sheet 110 having a six-layer structure of a first thin film layer 1101, a first implantation layer 1102, a first residual layer 1103, a second residual layer 1104, a second implantation layer 1105, and a second thin film layer 1106. The surfaces of the first thin film layer 1101 and the second thin film layer 1106 of the wafer implantation sheet 110 are cleaned at the semiconductor level to obtain a clean surface, which is conducive to the next step of bonding.

[0069] Two single crystal silicon carbide wafers with a diameter of 6 inches and a thickness of 0.5 mm and 0.55 mm, respectively, were cleaned at the semiconductor level to have clean surfaces, and were used as the first support substrate 120 and the second support substrate 130, respectively. The first film layer 1101 was directly contacted with the first support substrate 120, and the second film layer 1106 was directly contacted with the second support substrate 120, and they were bonded due to the van der Waals force to obtain the second bonded body 140.

[0070] The second bonding body 140 is subjected to heating annealing treatment at a temperature of 450° C. for 2 hours, so that the first film layer 1101 and the second film layer 1106 are separated from the first residual layer 1103 and the second residual layer 1104 respectively, and the first film layer 1101 and the second film layer 1106 are polished respectively, and at the same time, a first composite film including the first supporting substrate 120 and the first film layer 1101, a second composite film including the second supporting substrate 130 and the second film layer 1106, and a third bonding body 150 including the first residual layer 1103 and the second residual layer 1104 are obtained. At the same time, the third bonding body 150 is subjected to thinning and polishing treatment, and the above process is repeated as the first bonding body 100 to improve the utilization rate of the raw materials.

[0071] Example 3

[0072] Two polished lithium tantalate wafers with a diameter of 6 inches and a thickness of 1 mm were cleaned at the semiconductor level to have clean surfaces, and were used as the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 respectively.

[0073] The positive polarity surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 that are in direct contact are bonded together due to the Van der Waals force to obtain a first bonding body 100 .

[0074] Hydrogen ions are implanted on both sides of the first bonding body 100, with a dose of 5×10 18 ions / cm 2 The implantation energy is 500 KeV, forming a wafer implantation sheet 110 having a six-layer structure of a first thin film layer 1101, a first implantation layer 1102, a first residual layer 1103, a second residual layer 1104, a second implantation layer 1105 and a second thin film layer 1106. The surfaces of the first thin film layer 1101 and the second thin film layer 1106 of the wafer implantation sheet 110 are cleaned at the semiconductor level to obtain a clean surface, which is conducive to the next step of bonding.

[0075] Two single crystal silicon carbide wafers with a diameter of 12 inches and a thickness of 1 mm are cleaned at the semiconductor level to have clean surfaces, and are respectively used as the first support substrate 120 and the second support substrate 130. The first film layer 1101 is directly in contact with the first support substrate 120, and the second film layer 1106 is directly in contact with the second support substrate 120, and they are bonded to each other due to the van der Waals force, thereby obtaining a second bonded body 140.

[0076] The second bonding body 140 is subjected to heating annealing treatment at a temperature of 800° C. for 0.5 h, so that the first film layer 1101 and the second film layer 1106 are separated from the first residual layer 1103 and the second residual layer 1104 respectively, and the first film layer 1101 and the second film layer 1106 are polished respectively, and at the same time, a first composite film including the first supporting substrate 120 and the first film layer 1101, a second composite film including the second supporting substrate 130 and the second film layer 1106, and a third bonding body 150 including the first residual layer 1103 and the second residual layer 1104 are obtained. At the same time, the third bonding body 150 is subjected to thinning and polishing treatment, and the above process is repeated as the first bonding body 100 to improve the utilization rate of the raw materials.

[0077] Example 4

[0078] Two lithium tantalate polished wafers with a diameter of 4 inches and a thickness of 0.25 mm were cleaned at the semiconductor level to have clean surfaces, and were used as the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 respectively.

[0079] The positive polarity surfaces of the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are directly contacted, and due to the action of the van der Waals force, the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 are bonded together to obtain the first bonding body 100 .

[0080] Helium ions are implanted on both sides of the first bonding body 100, with a dose of 3×10 15 ions / cm 2 The implantation energy is 200 KeV, forming a wafer implantation sheet 110 having a six-layer structure of a first thin film layer 1101, a first implantation layer 1102, a first residual layer 1103, a second residual layer 1104, a second implantation layer 1105 and a second thin film layer 1106. The surfaces of the first thin film layer 1101 and the second thin film layer 1106 of the wafer implantation sheet 110 are cleaned at the semiconductor level to obtain a clean surface, which is conducive to the next step of bonding.

[0081] Two single crystal silicon carbide wafers with a diameter of 4 inches and a thickness of 0.25 mm are cleaned at the semiconductor level to have clean surfaces, and are respectively used as the first support substrate 120 and the second support substrate 130. The first film layer 1101 is directly in contact with the first support substrate 120, and the second film layer 1106 is directly in contact with the second support substrate 120, and they are bonded to each other due to the van der Waals force, thereby obtaining a second bonded body 140.

[0082] The second bonding body 140 is subjected to heating annealing treatment at a temperature of 80°C for 60 hours to separate the first thin film layer 1101 and the second thin film layer 1106 from the first residual layer 1103 and the second residual layer 1104 respectively, and the first thin film layer 1101 and the second thin film layer 1106 are polished respectively to obtain a first composite thin film including a first supporting substrate 120 and the first thin film layer 1101, a second composite thin film including a second supporting substrate 130 and a second thin film layer 1106, and a third bonding body 150 including the first residual layer 1103 and the second residual layer 1104.

[0083] Comparative Example 1

[0084] A 4-inch diameter, 0.5 mm thick lithium tantalate polished wafer was cleaned at semiconductor level to have a clean surface. Hydrogen ions were implanted on both sides of the lithium tantalate polished wafer, with a dose of 5×10 16 ions / cm 2The implantation energy is 200 KeV, forming a wafer implantation sheet with a five-layer structure of a first film layer, a first implantation layer, a residual layer, a second implantation layer and a second film layer. The thickness of the first film layer and the second film layer are both 500 nm. The surfaces of the first film layer and the second film layer of the wafer implantation sheet are cleaned at the semiconductor level to obtain a clean surface, which is conducive to the next step of bonding.

[0085] Two single crystal silicon carbide wafers with a diameter of 4 inches and a thickness of 0.5 mm are cleaned at the semiconductor level to have clean surfaces, and are used as the first support substrate and the second support substrate, respectively. The first film layer is directly contacted with the first support substrate, and the second film layer is directly contacted with the second support substrate, and they are bonded to each other due to the action of van der Waals force to obtain a second bonded body.

[0086] The second bonding body is subjected to heating annealing treatment at a temperature of 280°C for 10 hours to separate the first thin film layer and the second thin film layer from the residual layer, and the first thin film layer and the second thin film layer are polished respectively to obtain a first composite thin film including a first supporting substrate and a first thin film layer 1, a second composite thin film including a second supporting substrate and a second thin film layer, and a residual layer.

[0087] The warpage and curvature tests were performed on the composite films obtained in Examples 1 to 4 and Comparative Example 1. The results are shown in Table 1.

[0088] Table 1 Warpage and curvature of composite films

[0089]

[0090]

[0091] By comparing the warping degrees of the composite films in Example 1 and Comparative Example 1, since the first bonding body 100 obtained by bonding the first piezoelectric wafer 1001 and the second piezoelectric wafer 1002 in Example 1 replaces the piezoelectric wafer in Comparative Example 1, the thermal stress warping problem of the piezoelectric wafer during the ion implantation process can be effectively improved, and the yield of the piezoelectric single crystal film can be improved.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite film for reducing wafer warpage, characterized in that: The following steps are involved: S1, bonding a first piezoelectric wafer and a second piezoelectric wafer to obtain a first bonding body; S2, performing double-sided ion implantation on the first bonding body to obtain an implanted wafer including a first thin film layer, a first implantation layer, a first residual layer, a second residual layer, a second implantation layer and a second thin film layer in sequence; S3, bonding the first film layer to the first supporting substrate, and bonding the second film layer to the second supporting substrate, to obtain a second bonded body; S4, heating and annealing the second bonding body to obtain a first composite film including a first supporting substrate and a first film layer, a second composite film including a second supporting substrate and a second film layer, and a third bonding body including a first residual substance layer and a second residual substance layer.

2. The method for preparing a composite film according to claim 1, characterized in that: The materials of the first piezoelectric wafer and the second piezoelectric wafer are the same or different, including at least one of lithium niobate, lithium tantalate, quartz, lithium tetraborate and lanthanum gallium silicate; the thicknesses of the first piezoelectric wafer and the second piezoelectric wafer are the same or different, and are 0.2 to 1 mm; the bonding surfaces of the first piezoelectric wafer and the second piezoelectric wafer have the same polarity.

3. The method for preparing a composite film according to claim 1, characterized in that: The ions implanted include at least one of hydrogen ions and helium ions, with an energy of 50 to 500 KeV and a dose of 3×10 15 ~5×10 18 ions / cm 2 .

4. The method for preparing a composite film according to claim 1, characterized in that: The thickness of the first thin film layer and the second thin film layer are the same or different, and are 50-1000 nm.

5. The method for preparing a composite film according to claim 1, characterized in that: The materials of the first support substrate and the second support substrate are the same or different, including at least one of sapphire, silicon, silicon carbide, quartz, diamond, gallium nitride and gallium arsenide; the thicknesses of the first support substrate and the second support substrate are the same or different, and are 0.2 to 1 mm.

6. The method for preparing a composite film according to claim 1, characterized in that: The diameters of the first supporting substrate, the second supporting substrate, the first piezoelectric wafer and the second piezoelectric wafer are the same, which is 4 to 12 inches.

7. The method for preparing a composite film according to claim 1, characterized in that: The heating annealing temperature is 80° C. to 800° C., and the time is 0.5 to 60 hours.

8. The method for preparing a composite film according to claim 1, characterized in that: The following steps are also included: S5. Use the third bonding body as the first bonding body and repeat steps S2 to S4.

9. A composite film, characterized in that: The composite film is obtained by the composite film preparation method according to any one of claims 1 to 8.

10. Use of the composite film according to claim 9 in preparing semiconductor devices including radio frequency filters.

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