Composite film and method for producing the same

Abstract

The embodiment of the present application provides a composite film and a preparation method thereof, which comprises the following steps: preparing a first isolation layer on the surface of a first substrate layer to obtain a first combination; preparing a defect layer on the surface of a second substrate layer to obtain a second combination; bonding the surface of a functional layer with the surface of the first isolation layer in the first combination to obtain a first bonded body; removing the first substrate layer on the surface of the first bonded body to obtain a second bonded body; and bonding the second combination with the second bonded body to obtain the composite film. Through the arrangement of the embodiment of the present application, a preparation method of the composite film capable of optimizing the performance of an electronic device is provided, and the production time of the composite film prepared by the preparation method is relatively short, and the production efficiency is relatively high.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a composite thin film and its preparation method. Background Technology

[0002] Composite thin films can meet the requirements of miniaturization, low power consumption, and high performance in electronic components, thus becoming an increasingly important material in the semiconductor industry. Composite thin films consist of at least a defect layer and an isolation layer stacked sequentially. An isolation layer with a thickness exceeding 7 μm can block signal crosstalk between the thin film layers on both sides of the isolation layer, while the defect layer can further optimize the performance of electronic components.

[0003] In related technologies, composite films are usually prepared by conventional layering, that is, by preparing an isolation layer on the surface of the defect layer.

[0004] However, due to the temperature requirements of the defect layer, it takes a long time and has low production efficiency to directly prepare an isolation layer with a thickness of more than 7 μm on the surface of the defect layer. Summary of the Invention

[0005] This application provides a composite thin film and its preparation method to solve the technical problem in the related art that the preparation of an isolation layer with a thickness of more than 7 μm on the surface of the defect layer is time-consuming and has low production efficiency due to the process temperature requirements of the defect layer.

[0006] In a first aspect, embodiments of this application provide a method for preparing a composite thin film, comprising the following steps:

[0007] A first insulating layer is prepared on the surface of a first substrate to obtain a first conjugate;

[0008] A defect layer is prepared on the surface of the second substrate to obtain a second aggregate;

[0009] The surface of the functional layer is bonded to the surface of the first isolation layer in the first composite to obtain the first composite.

[0010] The second bond is obtained by removing the first substrate layer from the surface of the first bond;

[0011] The second conjugate is bonded to the second bond to obtain a composite film.

[0012] In one feasible implementation, an isolation layer is formed between the defect layer and the functional layer, and the isolation layer includes at least a first isolation layer.

[0013] In one feasible implementation, the thickness of the first isolation layer is equal to the thickness of the isolation layer.

[0014] In one feasible implementation, the second conjugate is bonded to the second bond to obtain a composite film, specifically including the following steps:

[0015] The surfaces of the defect layer in the second composite and the first isolation layer in the second bond are activated to bond the second composite and the second bond to obtain a composite film.

[0016] In one feasible implementation, the preparation of a defect layer on the surface of the second substrate to obtain the second aggregate specifically includes the following steps:

[0017] After depositing a defect layer on the surface of the second substrate, a second isolation layer is prepared on the surface of the defect layer to obtain a second composite; wherein the sum of the thickness of the first isolation layer and the thickness of the second isolation layer is equal to the thickness of the isolation layer, and the thickness of the second isolation layer is less than the thickness of the first isolation layer.

[0018] In one feasible implementation, the second conjugate is bonded to the second bond to obtain a composite film, specifically including the following steps:

[0019] The surfaces of the second isolation layer in the second composite and the first isolation layer in the second bond are activated to bond the second composite and the second bond to obtain a composite film.

[0020] In one feasible implementation, the second isolation layer is prepared by thermal oxidation or deposition.

[0021] In one feasible implementation, the thickness of the isolation layer is 7μm to 25μm.

[0022] In one feasible implementation, after the step of bonding the second conjugate to the second bonded conjugate to obtain the composite film, the method further includes:

[0023] The target composite film is obtained by grinding and thinning the functional layer in the composite film to the target thickness.

[0024] In one feasible implementation, bonding the functional layer to the surface of the first isolation layer in the first bonded body to obtain the first bonded body specifically includes the following steps:

[0025] The surface of the functional layer and the surface of the first isolation layer in the first bond are activated respectively to bond the functional layer to the first bond to obtain the first bond.

[0026] In one feasible implementation, the first substrate layer is made of silicon or SOI;

[0027] The second substrate layer is made of one of the following materials: silicon, SOI, quartz, sapphire, or silicon carbide.

[0028] In one feasible implementation, the functional layer is made of one of the following materials: lithium niobate crystal material, potassium titanium oxyphosphate crystal material, or rubidium titanium oxyphosphate crystal material.

[0029] Secondly, embodiments of this application also provide a composite thin film, prepared using a composite thin film preparation method of any of the technical solutions in the first aspect, wherein the composite thin film includes at least a second substrate layer, a defect layer, an isolation layer and a functional layer stacked sequentially; wherein the thickness of the isolation layer is 7μm to 25μm.

[0030] In a first aspect, embodiments of this application also provide a method for preparing a composite thin film. This involves preparing a first isolation layer on the surface of a first substrate, preparing a defect layer on the surface of a second substrate, and then bonding the prepared second binder and second bond to obtain a composite thin film with a defect layer and a relatively thick isolation layer, capable of optimizing the performance of electronic devices. In this embodiment, by preparing the defect layer and the first isolation layer separately, the method avoids the need to limit the preparation temperature of the first isolation layer on the surface of the defect layer to reduce the influence of temperature on the defect layer lattice, thus avoiding a longer preparation time for the first isolation layer. Therefore, the method described in this embodiment can shorten the preparation time of the first isolation layer and improve production efficiency. This embodiment provides a method for preparing a composite thin film capable of optimizing the performance of electronic devices, and this method results in a shorter production time and higher production efficiency.

[0031] Secondly, embodiments of this application provide a composite thin film, which includes at least a second substrate layer, a defect layer, an isolation layer, and a functional layer stacked sequentially. The thickness of the isolation layer is set to 7 μm to 25 μm. The relatively thick isolation layer effectively blocks signal crosstalk between the defect layer and the functional layer, and the presence of a defect layer on the surface of the isolation layer further optimizes the performance of the electronic device. Therefore, embodiments of this application provide a composite thin film that effectively blocks signal crosstalk between the defect layer and the functional layer and optimizes the performance of the electronic device. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 This is a schematic diagram of the structure of a composite thin film provided in an embodiment of this application. Figure 1 ;

[0034] Figure 2 This is a schematic diagram of the structure of a composite thin film provided in an embodiment of this application. Figure 2 ;

[0035] Figure 3 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 1 ;

[0036] Figure 4 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 2 ;

[0037] Figure 5 yes Figure 3 The steps of a method for preparing a composite thin film Figure 1 ;

[0038] Figure 6 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 3 ;

[0039] Figure 7 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 4 ;

[0040] Figure 8 yes Figure 6 The steps of a method for preparing a composite thin film Figure 2 .

[0041] Explanation of reference numerals in the attached figures:

[0042] 11-First bond; 12-First bond; 13-Second bond; 14-Second bond; 15-Target composite film;

[0043] 101-First substrate layer; 102-First isolation layer; 103-Functional layer; 104-Second substrate layer; 105-Defect layer; 106-Second isolation layer; 107-Isolation layer. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0045] It should be noted that many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0046] Composite thin films can meet the requirements of miniaturization, low power consumption, and high performance in electronic components, thus becoming an increasingly important material in the semiconductor industry. Composite thin films consist of at least a defect layer and an isolation layer stacked sequentially. An isolation layer with a thickness exceeding 7 μm can block signal crosstalk between the thin film layers on both sides of the isolation layer, while the defect layer can further optimize the performance of electronic components.

[0047] In related technologies, composite films are usually prepared by conventional layering, that is, by preparing an isolation layer on the surface of the defect layer.

[0048] However, due to the temperature requirements of the defect layer, it takes a long time to prepare an isolation layer with a thickness of more than 7 μm on the surface of the defect layer, resulting in low production efficiency.

[0049] Therefore, this application provides a composite film and its preparation method to solve the technical problem in the related art that the preparation of an isolation layer with a thickness of more than 7 μm on the surface of the defect layer takes a long time and has low production efficiency due to the process temperature requirements of the defect layer.

[0050] Figure 1 This is a schematic diagram of the structure of a composite thin film provided in an embodiment of this application. Figure 1 ; Figure 2 This is a schematic diagram of the structure of a composite thin film provided in an embodiment of this application. Figure 2 .

[0051] Reference Figure 1 and Figure 2 This application provides a composite film, which includes at least a second substrate layer 104, a defect layer 105, an isolation layer 107 and a functional layer 103 stacked sequentially; wherein the thickness of the isolation layer 107 is 7μm to 25μm.

[0052] For example, the second substrate 104 can be made of one of silicon, SOI, quartz, sapphire, or silicon carbide, and the thickness of the second substrate 104 can be set to 0.3 mm to 0.8 mm. Figure 2 In the middle, the second substrate layer is made of SI material.

[0053] For example, the defect layer 105 is deposited on the surface of the second substrate layer 104. Figure 2 In the process, the defect layer 105 is a P-SI layer, and the thickness of the defect layer 105 is 300nm to 500nm.

[0054] For example, the isolation layer 107 is an SiO2 layer obtained by oxidation on the surface of the first substrate layer 101, wherein the thickness of the isolation layer 107 is 7 μm to 25 μm. It should be noted that when the thickness of the isolation layer 107 is less than 7 μm, its ability to block signal crosstalk between the defect layer 105 and the functional layer 103 is poor. When the thickness of the isolation layer 107 is greater than 25 μm, it not only prolongs the growth cycle of the isolation layer 107 and increases the cost of the composite film, but also increases the thickness of the composite film, which is not conducive to assembly with electronic devices. Therefore, setting the thickness of the isolation layer 107 to 7 μm to 25 μm can not only effectively block signal crosstalk between the defect layer 105 and the functional layer 103, but also improve the production efficiency of the composite film.

[0055] For example, the functional layer 103 can be made of one of the following materials: lithium niobate crystal material, potassium titanium oxyphosphate crystal material, or rubidium titanium oxyphosphate crystal material. The thickness of the functional layer 103 can be set to 50 nm to 300 nm. Figure 2 In the middle, the functional layer is made of lithium niobate crystal material (LN).

[0056] This application provides a composite thin film, which includes at least a second substrate layer 104, a defect layer 105, an isolation layer 107, and a functional layer 103 stacked sequentially. The thickness of the isolation layer 107 is set to 7 μm to 25 μm. The relatively thick isolation layer 107 effectively blocks signal crosstalk between the defect layer 105 and the functional layer 103, and the presence of the defect layer 105 on the surface of the isolation layer 107 further optimizes the performance of the electronic device. Therefore, this application provides a composite thin film that effectively blocks signal crosstalk between the defect layer 105 and the functional layer 103 and optimizes the performance of the electronic device.

[0057] Based on the composite film having a defect layer 105 and an isolation layer 107 with a thickness exceeding 7 μm, the related technology uses a lamination method to directly prepare the isolation layer 107 on the surface of the defect layer 105. However, due to the process temperature requirements of the defect layer 105, preparing the isolation layer 107 with a thickness exceeding 7 mm on the surface of the defect layer 105 takes a long time and has low production efficiency. The present application provides a method for preparing a composite film to solve the above-mentioned technical problems.

[0058] Example 1:

[0059] Figure 3 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 1 ; Figure 4 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 2 ; Figure 5 yes Figure 3 The steps of a method for preparing a composite thin film Figure 1 .

[0060] This application provides a method for preparing a composite thin film. In specific implementation, refer to... Figures 3 to 5 This includes the following steps:

[0061] S100: A first isolation layer 102 is prepared by thermal oxidation on the surface of the first substrate layer 101 to obtain a first conjugate 11.

[0062] For example, refer to Figure 4 Taking the first substrate layer 101 as an example of using a SI substrate, a SI / SiO2 structure, i.e., the first bond 11, is formed by thermal oxidation on the surface of the SI substrate. In specific implementation, the oxidation temperature of thermal oxidation is 500℃±50℃.

[0063] It should be noted that thermal oxidation is the process of oxidizing SI with oxygen on the surface of the SI substrate to form an SiO2 oxide layer. The SiO2 oxide layer formed in S100 is the first isolation layer 102.

[0064] Of course, in specific implementations, the first substrate layer 101 can be made of SOI in addition to SI substrate.

[0065] S200: A defect layer 105 is prepared by deposition on the surface of the second substrate layer 104 to obtain the second aggregate 14.

[0066] For example, refer to Figure 4 Taking the second substrate layer 104 as an example, an SI / P-SI structure, i.e., the second composite 14, is formed by deposition on the surface of the SI substrate.

[0067] It should be noted that the deposition disclosed in this embodiment is the process of depositing a P-SI layer on the surface of an SI substrate, wherein the P-SI layer formed in S200 is the defect layer 105.

[0068] For example, in order to ensure that the lattice of the P-SI layer is not affected, the SI substrate is kept at the constant temperature required for P-SI during deposition.

[0069] S300: Bond the surface of the functional layer 103 to the surface of the first isolation layer 102 in the first bonded body 11 to obtain the first bonded body 12.

[0070] In specific implementation, the surfaces of the functional layer 103 and the first isolation layer 102 are activated to bond the functional layer 103 to the first bonded body 11, thereby obtaining the first bonded body 12.

[0071] For example, functional layer 103 is made of a wafer. In specific implementations, functional layer 103 can be made of one of the following materials: lithium niobate crystal material, potassium titanium oxyphosphate crystal material, or rubidium titanium oxyphosphate crystal material. In the embodiments of this application, refer to... Figure 4 The functional layer 103 can be made of lithium niobate material, that is, the functional layer 103 is an LN wafer, that is, the first bond 12 is a SI / SiO2 / LN structure.

[0072] S400: Remove the first substrate layer 101 from the surface of the first bond 12 to obtain the second bond 13.

[0073] For example, the first substrate layer 101 can be etched away using chemical etching.

[0074] For example, refer to Figure 4 The SI substrate was etched away using a chemical etching method to obtain the second bond 13, wherein the second bond 13 is an SiO2 / LN structure.

[0075] S500: The surface of the defect layer 105 in the second composite 14 and the surface of the first isolation layer 102 in the second bonded body 13 are activated respectively to bond the second composite 14 and the second bonded body 13 to obtain a composite film.

[0076] Specifically, an isolation layer 107 is formed between the defect layer 105 and the functional layer 103. The thickness of the isolation layer 107 is 7μm to 25μm, and the thickness of the isolation layer 107 is equal to the thickness of the first isolation layer 102.

[0077] In specific implementation, refer to Figure 4 That is, the surface of the defect layer 105 and the surface of the first isolation layer 102 are activated respectively. For example, the surface of P-SI in SI / P-SI and the surface of SiO2 in the SiO2\LN structure are activated, and then the activated surfaces are bonded to obtain the SI / P-SI / SIO2 / LN structure.

[0078] For example, if the workers want to obtain an isolation layer 107 with a thickness of 12 μm, the thickness of the first isolation layer 102 would be 11 μm. No specific limitation is made here, as long as the thickness of the isolation layer 107 is equal to the thickness of the first isolation layer 102.

[0079] S600: Thinning and grinding the functional layer 103 in the composite film to the target thickness to obtain the target composite film 15.

[0080] For example, the composite film can be obtained by grinding and thinning the LN layer in the SI / P-SI / SiO2 / LN structure to the target thickness.

[0081] Example 2:

[0082] Figure 6 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 3 ; Figure 7 This application provides a method flow chart for preparing a composite thin film according to an embodiment. Figure 4 ; Figure 8 yes Figure 6 The steps of a method for preparing a composite thin film Figure 2 .

[0083] This application provides a method for preparing a composite thin film. In specific implementation, refer to... Figures 6 to 8 This includes the following steps:

[0084] S100: A first isolation layer 102 is prepared by thermal oxidation on the surface of the first substrate layer 101 to obtain a first conjugate 11.

[0085] For example, refer to Figure 7 Taking the first substrate layer 101 as an example of using a SI substrate, a SI / SiO2 structure, i.e., the first bond 11, is formed by thermal oxidation on the surface of the SI substrate. In specific implementation, the oxidation temperature of thermal oxidation is 500℃±50℃.

[0086] It should be noted that thermal oxidation is the process of oxidizing SI with oxygen on the surface of the SI substrate to form an SiO2 oxide layer. The SiO2 oxide layer formed in S100 is the first isolation layer 102.

[0087] Of course, in specific implementations, the first substrate layer 101 can be made of SOI in addition to SI substrate.

[0088] S200: After depositing a defect layer 105 on the surface of the second substrate layer 104, a second isolation layer 106 is prepared on the surface of the defect layer 105 to obtain a second conjugate 14.

[0089] It should be noted that the sum of the thickness of the first isolation layer 102 and the thickness of the second isolation layer 106 is equal to the thickness of the isolation layer 107.

[0090] For example, refer to Figure 7 Taking the second substrate layer 104 as an example, an SI / P-SI structure is deposited on the surface of the SI substrate, and then SiO2 (i.e., the second isolation layer 106) is prepared on the surface of the SI / P-SI structure by oxidation or deposition to form a SI / P-SI / SIO2 structure, which is the second conjugate 14.

[0091] It should be further noted that the thickness of the second isolation layer 106 is less than the thickness of the first isolation layer 102, and the thickness of both the first isolation layer 102 and the second isolation layer 106 is less than the thickness of the isolation layer 107.

[0092] S300: Bond the surface of the functional layer 103 to the surface of the first isolation layer 102 in the first bonded body 11 to obtain the first bonded body 12.

[0093] In specific implementation, the surfaces of the functional layer 103 and the first isolation layer 102 are activated respectively, and the functional layer 103 is bonded to the first bonding body 11 to obtain the first bonding body 12.

[0094] For example, functional layer 103 is made of a wafer. In specific implementations, functional layer 103 can be made of one of the following materials: lithium niobate crystal material, potassium titanium oxyphosphate crystal material, or rubidium titanium oxyphosphate crystal material. In the embodiments of this application, refer to... Figure 7 The functional layer 103 can be made of lithium niobate material, that is, the functional layer 103 is an LN wafer, and the first bond 12 is Si / SiO2. 2 / LN structure.

[0095] S400: Remove the first substrate layer 101 from the surface of the first bond 12 to obtain the second bond 13.

[0096] For example, the first substrate layer 101 can be etched away using chemical etching.

[0097] For example, refer to Figure 7 The SI substrate was etched away using a chemical etching method to obtain the second bond 13, wherein the second bond 13 is an SiO2 / LN structure.

[0098] S500: The surface of the second isolation layer 106 in the second composite 14 and the surface of the first isolation layer 102 in the second bonded body 13 are activated to bond the second composite 14 and the second bonded body 13 to obtain a composite film.

[0099] Specifically, an isolation layer 107 is formed between the defect layer 105 and the functional layer 103. The thickness of the isolation layer 107 is 7μm to 25μm. The thickness of the isolation layer 107 is equal to the sum of the thickness of the first isolation layer 102 and the thickness of the second isolation layer 106, wherein the thickness of the second isolation layer 106 is less than the thickness of the first isolation layer 102.

[0100] In specific implementation, the surfaces of the second isolation layer 106 and the first isolation layer 102 are respectively activated. For example, refer to... Figure 7The surface of SiO2 in the SI / P-SI / SIO2 structure and the surface of P-SI in SiO2 / LN are activated, and then the activated surfaces are bonded to obtain the SI / P-SI / SIO2 / LN structure.

[0101] For example, if the worker wants to obtain an isolation layer 107 with a thickness of 10 μm, the thickness of the first isolation layer 102 can be 4 μm and the thickness of the second isolation layer 106 can be 6 μm; or, the thickness of the first isolation layer 102 can be 3 μm and the thickness of the second isolation layer 106 can be 7 μm. No specific limitations are made here, as long as the thickness of the isolation layer 107 is equal to the sum of the thicknesses of the first isolation layer 102 and the second isolation layer 106.

[0102] S600: Thinning and grinding the functional layer 103 in the composite film to the target thickness to obtain the target composite film 15.

[0103] This application also provides a method for preparing a composite thin film. A first isolation layer 102 is prepared on the surface of a first substrate 101, and a defect layer 105 is prepared on the surface of a second substrate. The prepared second binder 14 and second bond 13 are then bonded together to obtain a composite thin film with a defect layer 105 and a relatively thick isolation layer 107, which can optimize the performance of electronic devices. In this application embodiment, by preparing the defect layer 105 and the first isolation layer 102 separately, the method avoids the need to limit the preparation temperature of the first isolation layer 102 on the surface of the defect layer 105 to reduce the influence of temperature on the lattice of the defect layer 105, thus avoiding a longer preparation time for the first isolation layer 102. Therefore, the method of this application embodiment can shorten the preparation time of the first isolation layer 102 and improve production efficiency. This application embodiment provides a method for preparing a composite thin film that can optimize the performance of electronic devices, and this method has a shorter production time and higher production efficiency.

[0104] It is readily understood that, based on the several embodiments provided in this application, those skilled in the art can combine, split, or reorganize the embodiments of this application to obtain other embodiments, none of which exceed the protection scope of this application.

[0105] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the embodiments of this application. It should be understood that the above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A method for preparing a composite thin film, characterized in that, Includes the following steps: A first insulating layer (102) is prepared on the surface of the first substrate layer (101) to obtain a first conjugate (11); A defect layer (105) is prepared on the surface of the second substrate layer (104) to obtain a second aggregate (14); The surface of the functional layer (103) is bonded to the first isolation layer (102) in the first composite (11) to obtain the first composite (12); The first substrate layer (101) on the surface of the first bonded body (12) is removed to obtain the second bonded body (13); The second composite material (14) is bonded to the second bonded material (13) to obtain a composite film.

2. The method for preparing a composite thin film according to claim 1, characterized in that, An isolation layer (107) is formed between the defect layer (105) and the functional layer (103), the isolation layer (107) including at least the first isolation layer (102).

3. The method for preparing a composite thin film according to claim 2, characterized in that, The thickness of the first isolation layer (102) is equal to the thickness of the isolation layer (107).

4. The method for preparing a composite thin film according to claim 3, characterized in that, The process of bonding the second conjugate (14) to the second bonded body (13) to obtain a composite film specifically includes the following steps: The surface of the defect layer (105) in the second composite (14) and the surface of the first isolation layer (102) in the second bonded body (13) are activated respectively to bond the second composite (14) and the second bonded body (13) to obtain the composite film.

5. The method for preparing a composite thin film according to claim 2, characterized in that, The process of preparing a defect layer (105) on the surface of the second substrate layer (104) to obtain the second aggregate (14) specifically includes the following steps: After depositing a defect layer (105) on the surface of the second substrate layer (104), a second isolation layer (106) is prepared on the surface of the defect layer (105) to obtain the second composite (14); wherein the sum of the thickness of the first isolation layer (102) and the thickness of the second isolation layer (106) is equal to the thickness of the isolation layer (107), and the thickness of the second isolation layer (106) is less than the thickness of the first isolation layer (102).

6. The method for preparing a composite thin film according to claim 5, characterized in that, The process of bonding the second conjugate (14) to the second bonded body (13) to obtain a composite film specifically includes the following steps: The surface of the second isolation layer (106) in the second composite (14) and the surface of the first isolation layer (102) in the second bonded body (13) are activated respectively to bond the second composite (14) and the second bonded body (13) to obtain the composite film.

7. The method for preparing a composite thin film according to claim 5, characterized in that, The second isolation layer (106) is prepared by thermal oxidation or deposition.

8. A method for preparing a composite thin film according to any one of claims 1-7, characterized in that, The thickness of the isolation layer (107) is 7μm to 25μm.

9. A method for preparing a composite thin film according to any one of claims 1-7, characterized in that, The step of bonding the second conjugate (14) to the second bonded body (13) to obtain a composite film further includes: The functional layer (103) in the composite film is thinned to the target thickness by grinding to obtain the target composite film (15).

10. A method for preparing a composite thin film according to any one of claims 1-7, characterized in that, The step of bonding the surface of the functional layer (103) to the surface of the first isolation layer (102) in the first bond (11) to obtain the first bonded body (12) specifically includes the following steps: The surface of the functional layer (103) and the surface of the first isolation layer (102) in the first bond (11) are activated respectively to bond the functional layer (103) to the first bond (12) to obtain the first bond (12).

11. A method for preparing a composite thin film according to any one of claims 1-7, characterized in that, The first substrate layer (101) is made of silicon or SOI; The second substrate (104) is made of one of the following materials: silicon, SOI, quartz, sapphire, or silicon carbide.

12. A method for preparing a composite thin film according to any one of claims 1-7, characterized in that, The functional layer (103) is made of one of the following materials: lithium niobate crystal material, potassium titanium oxyphosphate crystal material, or rubidium titanium oxyphosphate crystal material.

13. A composite film, characterized in that, The composite thin film is prepared by any one of claims 1-12, wherein the composite thin film comprises at least a second substrate layer (104), a defect layer (105), an isolation layer (107), and a functional layer (103) stacked sequentially; wherein the thickness of the isolation layer (107) is 7 μm to 25 μm.

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