Preparation method of single crystal composite film material

Abstract

The invention discloses a preparation method of a single crystal composite film material. The preparation method comprises the following steps: step 1, bonding a functional single crystal wafer and a substrate to form a bonding body; 2, reducing the thickness of the functional single crystal wafer through a wafer thinning process; 3, ion implantation is carried out on the surface of one side of the functional single crystal wafer in the bonding body, so that a stripping layer, a damaged layer and a thin film layer are sequentially formed from the surface of the functional single crystal wafer in the axial direction of the functional single crystal wafer, then the stripping layer and the thin film layer are separated from the damaged layer through annealing treatment, and the remaining damaged layer, the remaining thin film layer and the substrate form an initial single crystal composite thin film material; 4, removing a residual damaged layer in the initial single crystal composite thin film material obtained in the step 3 through a chemical mechanical polishing process, and then trimming the uniformity of the functional single crystal thin film layer; and step 5, repeating the steps 3-4 to reduce the thickness of the film layer of the functional crystal to the target thickness so as to obtain the single-crystal composite film material.

Description

Technical Field

[0001] The invention relates to the technical field of material process preparation, and in particular to a method for preparing a single crystal composite thin film material. Background Art

[0002] With the development of semiconductor technology, integrated circuits are gradually approaching their performance limits, and the applicability of Moore's Law is also facing challenges. In order to further improve device performance and reduce chip size, more and more attention is paid to the performance indicators and structural design requirements of the core materials of the device. Single-crystal composite thin film materials are the current development trend of semiconductor materials. Through efficient film layer structure design, they not only maintain the single crystal performance of functional materials and show excellent material properties, but also integrate the composite functions of multiple thin film materials, further enhancing the properties and advantages of the device, making up for the defects of the material, and being compatible with COMS technology to achieve system integration of multiple functional devices. It is the trend of functional crystal materials towards low-dimensionality, functional compositeness, and integration.

[0003] Conventional methods for preparing single-crystal composite thin film materials include intelligent stripping and thinning and polishing. The former combines ion implantation stripping with wafer bonding processes, and can generally control the film thickness of functional single crystals to less than 1.5μm. Limited by the relationship between ion implantation energy and depth, it is difficult to break through the preparation of thicker films. In addition, during the entire process, the damaged area passed by high-energy particles is retained on the substrate layer to form a functional single crystal film layer. Even if the damage can be repaired by high-temperature annealing later, it is difficult to return to the initial state of the wafer, which inhibits the performance of the back-end devices. The latter combines wafer bonding with grinding and thinning processes, and can generally control the thickness of functional single crystal films to more than 5μm. Under current process technology, the preparation of thinner functional single crystal layers based on this method will lead to poor uniformity inside the film and cause greater stress damage. The film thickness deviation in different regions exceeds 10% or even higher. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a single crystal composite thin film material, so as to solve the problems that the smart stripping method in the prior art is limited by the ion implantation energy and depth, and the performance of the damaged area where the high-energy particles pass is damaged, which inhibits the performance of the back-end device; at the same time, the thinning and polishing method is difficult to prepare a film with a thickness of less than 5μm, and the thinner functional single crystal layer prepared will lead to poor uniformity inside the film, causing greater stress damage, and making the film thickness deviation in different regions exceed 10% or even higher. The present invention combines wafer bonding, thinning, ion implantation and stripping processes, and uses the preparation method to achieve bonding of a functional single crystal wafer with a single substrate wafer material or a composite substrate substrate material with a certain film layer structure through a bonding process to form a bonding pair with a set function; the thickness of the functional crystal in the bonding pair is reduced through a thinning process; the functional crystal is further thinned through an ion implantation and stripping process; finally, the preparation of high-quality single crystal composite thin film materials is achieved through trimming and chemical mechanical polishing (CMP) processes. The functional single crystal film prepared by this method is not damaged by particle impact, and the single crystal property is the same as the original wafer state. Especially in the field of optical applications, it can avoid the formation of defects such as color centers inside the functional crystal caused by ion injection, inhibit the damage of the optical transmittance of the material, and the prepared film thickness range is wider, which not only covers the film control range of the intelligent stripping method and the thinning and polishing method, but also expands the preparation of the film in the thickness of 1~5μm, expanding the application range and usage scenarios of single crystal composite film materials. This method has simple process control, high degree of automation, is conducive to batch production, has good product consistency, and high uniformity within the film. It has practical guiding significance and application value for industrial production.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing a single crystal composite thin film material comprises the following steps: Step 1: Bonding the functional single crystal wafer and the substrate to form a bonded body; Step 2: Reduce the thickness of the functional single crystal wafer to a suitable range through a wafer thinning process; Step 3: ion implantation is performed on one side surface of the functional single crystal wafer in the bonded body, and a peeling layer, a damaged layer and a thin film layer are sequentially formed from the surface along the axial direction of the functional single crystal wafer, and then the peeling layer and the thin film layer are separated from the damaged layer by annealing, and the remaining damaged layer and the thin film layer form an initial single crystal composite thin film material with the substrate; Step 4: removing the remaining damaged layer in the initial single crystal composite thin film material obtained in step 3 by a chemical mechanical polishing process, and then adjusting the uniformity of the functional single crystal thin film layer; Step 5: Repeat steps 3 to 4 to reduce the thickness of the thin film layer of the functional crystal to the target thickness, thereby obtaining the single crystal composite thin film material; wherein the thickness of the thin film layer is 0.1 to 100 μm.

[0006] Preferably, the single crystal composite thin film material comprises a substrate, a surface of one side of the substrate having an oxide layer, and a functional single crystal thin film layer on the side of the oxide layer facing away from the substrate; or, the single crystal composite thin film material comprises a substrate, a surface of one side of the substrate having a compensation layer, an oxide layer on the side of the compensation layer facing away from the substrate, and a functional single crystal thin film layer on the side of the oxide layer facing away from the substrate.

[0007] Preferably, the substrate is selected from one of a silicon substrate, a silicon carbide substrate, a sapphire substrate, a gallium arsenide substrate, a gallium nitride substrate, an indium phosphide substrate, a spinel substrate, a diamond substrate, a quartz substrate, and an aluminum nitride substrate.

[0008] Preferably, the thickness of the substrate is 0.1-5 mm, and the thickness of the substrate is preferably 0.15-1.5 mm.

[0009] Preferably, the compensation layer is one of a silicon dioxide layer, a polysilicon layer, a silicon nitride layer, a gallium nitride layer, a gallium arsenide layer, and a Bragg reflection layer, and the thickness of the compensation layer is 0.1-15 μm, more preferably 0.1-4 μm.

[0010] Preferably, the oxide layer is a silicon dioxide layer or a polymer layer, and the thickness of the oxide layer is 0.1-20 μm, more preferably 0.3-10 μm.

[0011] Preferably, the functional single crystal wafer used for the functional single crystal thin film layer is selected from one of piezoelectric crystal, semiconductor crystal, ferroelectric crystal and laser crystal.

[0012] Preferably, the component of the functional single crystal wafer is selected from one of lithium tantalate, lithium niobate, lead magnesium niobate-lead titanate, gallium arsenide, gallium oxide, gallium nitride, gallium carbide, indium phosphide, gallium phosphide, silicon carbide, aluminum nitride, zinc oxide, diamond, and yttrium aluminum garnet; the thickness of the thin film layer is 0.3~50μm.

[0013] Preferably, the compensation layer is formed on the surface of the substrate by any one of chemical vapor deposition, physical vapor deposition, magnetron sputtering, liquid phase epitaxy, vapor phase epitaxy, and atomic layer deposition.

[0014] Preferably, the oxide layer is formed on the surface of the substrate or on the surface of the compensation layer facing away from the substrate by any one of chemical vapor deposition, magnetron sputtering, thermal oxidation, spin coating, and scraping.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the preparation method described in the present invention, the thinning and stripping technology is used, which can freely design the functional structure of the composite film layer and improve the working performance of the device prepared based on the single crystal composite thin film material; wherein, the thinning process can efficiently and significantly reduce the thickness of the functional wafer, and the ion implantation and stripping process can further reduce the thickness of the functional wafer without affecting the quality of the single crystal. The thickness of the functional single crystal thin film layer can be fine-tuned through the trimming process to improve the uniformity of the film, and finally obtain a high-quality single crystal composite thin film material.

[0016] 2. The thickness range of the functional single crystal thin film layer of the single crystal composite thin film material prepared by the method of the present invention makes up for the lack of thinning and polishing process and intelligent stripping process, and the quality of the prepared functional single crystal is further improved, especially in the field of optical applications. It can avoid the formation of defects such as color centers inside the functional crystal due to ion injection, inhibit the decline of the optical transmittance of the material, and improve the core performance indicators of the device prepared based on the single crystal composite thin film material, thereby improving the overall performance of the composite material, providing an effective solution for the batch and engineering preparation of single crystal composite thin film materials, and facilitating the miniaturization and multifunctionalization of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the film layer structure of the single crystal composite thin film material described in the present invention.

[0018] Figure 2 It is a schematic diagram of the structure of the oxide layer, compensation layer and substrate in the present invention.

[0019] Figure 3 The present invention is a flow chart of the preparation method.

[0020] Figure 4 This is a schematic diagram of the changes in the film structure formed after ion implantation of the bonded body in step 3 of the preparation method of the present invention.

[0021] Figure 5 This is a schematic diagram of the peeling process by annealing in step 3 of the preparation method of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the present invention belong to the scope of protection of the present invention.

[0023] Unless otherwise indicated in specific cases in the present invention, the numerical ranges listed herein include the upper and lower limits, and all integers and fractions within the range, and are not limited to the specific values ​​listed when defining the range.

[0024] 1. A method for preparing a single crystal composite thin film material The process of the preparation method of the present invention is as follows Figure 3 As shown, the specific steps are as follows: Step 1: Bond the functional single crystal wafer and the substrate to form a bonded body.

[0025] Step 2: Reduce the thickness of the functional single crystal wafer to an appropriate range through a wafer thinning process.

[0026] Step 3: Perform ion implantation on one side surface of the functional single crystal wafer in the bonding body, and sequentially form a peeling layer, a damaged layer and a thin film layer from the surface along the axial direction of the functional single crystal wafer, and then separate the peeling layer and the thin film layer from the damaged layer through annealing treatment, and the remaining damaged layer and the thin film layer form an initial single crystal composite thin film material with the substrate.

[0027] Step 4: Remove the remaining damaged layer in the initial single crystal composite thin film material obtained in step 3 through a chemical mechanical polishing process, and then adjust the uniformity of the functional single crystal thin film layer.

[0028] Step 5: Repeat steps 3 and 4 for multiple times to reduce the thickness of the thin film layer of the functional crystal to the target thickness, thereby obtaining the single crystal composite thin film material; wherein the thickness of the thin film layer is 0.1 to 100 μm.

[0029] After conducting an in-depth study on the methods for preparing single crystal composite thin film materials in the prior art, the present invention found that the functional single crystal thin film layers prepared by these methods not only have defects in thickness, but also affect the performance of the back-end device. In the preparation method described in the present invention, the thinning and stripping technology is adopted, which can freely design the functional structure of the composite film layer and improve the working performance of the device prepared based on the single crystal composite thin film material. Among them, the thinning process can efficiently and significantly reduce the thickness of the functional wafer, and the ion implantation and stripping process can further reduce the thickness of the functional wafer without affecting the quality of the single crystal. The thickness of the functional single crystal thin film layer can be fine-tuned through the trimming process to improve the uniformity of the film, and finally obtain a high-quality single crystal composite thin film material. The single crystal composite thin film material prepared by this method has a functional single crystal thin film layer thickness range that makes up for the lack of thinning and polishing process and intelligent stripping process, and the quality of the prepared functional single crystal has been further improved, especially in the field of optical applications, which can avoid the formation of defects such as color centers inside the functional crystal due to ion implantation, thereby improving the overall performance of the composite material, and providing an effective solution for the batch and engineering preparation of single crystal composite thin film materials.

[0030] In some embodiments of the present invention, the specific material of the substrate can be selected based on the performance index requirements of the functional materials and the device, and a material with a high sound velocity can be selected according to the needs to suppress the leakage of energy such as sound waves, or a high heat dissipation substrate material can be selected to achieve high-power device preparation, or a material with a temperature compensation effect can be selected to improve the stability of the device. Therefore, the substrate is selected from one of a silicon substrate, a silicon carbide substrate, a sapphire substrate, a gallium arsenide substrate, a gallium nitride substrate, an indium phosphide substrate, a spinel substrate, a diamond substrate, a quartz substrate, and an aluminum nitride substrate.

[0031] In some embodiments of the present invention, the functional single crystal wafer used to form the functional single crystal thin film layer is selected from one of piezoelectric crystals, semiconductor crystals, ferroelectric crystals, and laser crystals. More specifically, the components of the single crystal wafer can be lithium tantalate, lithium niobate, lead magnesium niobate-lead titanate, gallium arsenide, gallium oxide, gallium nitride, gallium carbide, indium phosphide, gallium phosphide, silicon carbide, aluminum nitride, zinc oxide, diamond, yttrium aluminum garnet, etc. Among them, the thickness of the functional single crystal thin film layer that can be prepared by the method of the present invention is 0.1~100μm, further optimized to 0.3~50μm, and further optimized to 1.5~5μm.

[0032] In some embodiments of the present invention, Figure 1~2 As shown, there is an oxide layer on one side surface of the substrate; or, a compensation layer is first formed on one side surface of the substrate, and then an oxide layer is formed on the surface of the compensation layer and on the side of the compensation layer away from the substrate. Among them, a new film layer is added between the substrate and the functional single crystal thin film layer, which can be used to improve the core performance indicators of the device, such as setting an oxide layer to suppress energy loss and improve energy efficiency; or further, a compensation layer is set between the oxide layer and the substrate to compensate for the temperature performance of the device, improve the use range of the device and the use state under extreme environments; or, the oxide layer or the compensation layer can be used as a transition layer to enable the substrate and the functional crystal with large lattice constant differences to be bonded together, etc.

[0033] In some embodiments of the present invention, the compensation layer may be a silicon dioxide layer, a polysilicon layer, a silicon nitride layer, a gallium nitride layer, a gallium arsenide layer, a Bragg reflection layer, etc. The compensation layer may be formed by chemical vapor deposition, physical vapor deposition, magnetron sputtering, liquid phase epitaxy, vapor phase epitaxy, atomic layer deposition, etc. The thickness of the compensation layer is 0.1 to 15 μm, preferably 0.1 to 4 μm, and may be 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 3 μm, 4 μm, 5 μm, 10 μm, 12 μm, 15 μm, etc., and all ranges and sub-ranges between the above values.

[0034] In some embodiments of the present invention, the oxide layer may be a silicon dioxide layer, a polymer layer, etc. The oxide layer may be formed on the surface of the substrate or on the surface of the compensation layer away from the substrate by any one of chemical vapor deposition, magnetron sputtering, thermal oxidation, spin coating, and scraping. The oxide layer has a thickness of 0.1 to 20 μm, preferably 0.3 to 10 μm, and may be 0.1 μm, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, etc., and all ranges and sub-ranges between the above values.

[0035] In some embodiments of the present invention, in step 1, the functional single crystal wafer and the oxide layer on the substrate are bonded to form a bonded body through a wafer bonding method such as a room temperature bonding process, a surface activated bonding process or a polymer bonding process.

[0036] In some embodiments of the present invention, in step 2, the functional single crystal wafer on the bonded body is reduced to a suitable range through a wafer thinning process. The purpose of this step is to first reduce the thickness of the wafer to a value close to the target thickness of the thin film layer, so that the subsequent process can further reduce the thickness of the functional single crystal wafer. When the thickness of the functional single crystal wafer is reduced by the wafer thinning process, not only the thickness of the thinned functional single crystal wafer must be greater than the thickness of the final target thin film layer, but also the thinned functional single crystal wafer must have sufficient thickness to ensure that the subsequent processing can proceed normally, and finally the thin film layer reaches the required thickness. If a thin film layer with a thickness of 1.5~5μm is to be prepared, in step 2, the thickness of the functional single crystal wafer cannot be less than 5μm, but it is not too thick, not exceeding 10μm; and if a thin film layer of other thickness is to be prepared, the thickness control of the functional single crystal wafer in step 2 is the same.

[0037] In some embodiments of the present invention, in step 3, Figures 4 and 5 As shown, the functional single crystal wafer in the bonded body is subjected to H + or He + Ion implantation is carried out from the side of the functional single crystal wafer facing away from the substrate. Ions of a certain energy and dose are injected into the functional single crystal wafer, and a peeling layer, a damaged layer and a thin film layer are formed in sequence from the surface along the axial direction of the functional single crystal wafer. Among them, the area where the injected ions pass is the peeling layer, and the area where the movement of the injected ions ends will form a certain thickness inside the functional single crystal wafer, which is called the damaged layer. Other areas that are not passed by the injected ions are called thin film layers. The peeling layer and the thin film layer are separated from the damaged layer through a suitable annealing process. The thin film layer and the remaining damaged layer form the initial single crystal composite thin film material with the composite substrate. The specific structure is shown in the figure.

[0038] In some embodiments of the present invention, in step 4, the remaining damaged layer in the initial single crystal composite thin film material obtained in step 3 is removed by a chemical mechanical polishing process, and then the uniformity of the functional single crystal thin film layer is adjusted to improve the uniformity of the single crystal thin film layer.

[0039] In some embodiments of the present invention, in step 5, steps 3 to 4 are repeated multiple times to reduce the thickness of the thin film layer of the functional crystal to the target thickness, and obtain the single crystal composite thin film material; wherein the thickness of the thin film layer is 0.1 to 100 μm, and further, the method of the present invention can obtain a thin film layer with a thickness of 0.3 to 50 μm, and more importantly, a thin film layer with a thickness between 1.5 and 5 μm can be obtained, thereby solving the technical problem that the prior art cannot obtain a thin film layer with a thickness between 1.5 μm and 5 μm. Therefore, the thickness of the thin film layer prepared by the method of the present invention can be 0.1 μm, 0.3 μm, 1.0 μm, 1.5 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, etc., as well as all ranges and sub-ranges between the above values.

[0040] In some embodiments of the present invention, based on different functional requirements, single crystal composite thin film materials with different film layer structures can be designed to improve device performance with materials as the core, and to achieve the preparation and development of high-quality devices, such as lasers, filters, LED devices, detectors, power devices, MEMS devices, modulators, etc., which have broad application value and important strategic significance in the fields of mobile communications, integrated optics, aerospace, etc.

[0041] 2. Examples and Comparative Examples Example 1 A silicon substrate is used as a substrate substrate, the thickness of the substrate substrate is 1 mm, a silicon dioxide layer is formed on its surface as an oxide layer by chemical deposition method, the thickness of the oxide layer is 1 μm. Lithium tantalate is used as a functional single crystal wafer to prepare a single crystal composite thin film material.

[0042] Step 1: Bond the functional single crystal wafer and the oxide layer of the substrate substrate through a room temperature bonding process to form a bonded body.

[0043] Step 2: Reduce the thickness of the functional single crystal wafer to 5 μm by a wafer thinning process, wherein the wafer thinning process is performed by a conventional process in the prior art.

[0044] Step 3: H-treat one side of the functional single crystal wafer in the bonded body. +Ion implantation is performed to sequentially form a peeling layer, a damaged layer and a thin film layer from the surface along the axial direction of the functional single crystal wafer, and then the peeling layer and the thin film layer are separated from the damaged layer by annealing, and the remaining damaged layer and the thin film layer form an initial single crystal composite thin film material with the substrate. The annealing is performed using conventional processes in the prior art.

[0045] Step 4: Remove the remaining damaged layer in the initial single crystal composite thin film material obtained in step 3 through a chemical mechanical polishing process, and then adjust the uniformity of the functional single crystal thin film layer.

[0046] Step 5: Repeat steps 3 to 4 2 to 3 times to reduce the film thickness of the functional crystal to the target thickness, and obtain the single crystal composite film material. The film thickness of the prepared single crystal composite film material is 3 μm.

[0047] According to the process sequence of Example 1, using the parameters in Table 1, Examples 2 to 6 are prepared. In Examples 2 to 6, except for the parameters in Table 1, the other steps are exactly the same as those in Example 1. The purpose of setting the embodiments and comparative examples of the present invention is to compare the effect of the processing sequence on the thickness of the thin film layer, so the processes used therein are all processes of the prior art, and the specific parameters can refer to the parameters of the process in the prior art. The method of the present invention has a wide range of application, so that there are many types of combinations of substrate substrates and functional wafers, which cannot be exhaustively listed, so the following examples are used for verification and explanation.

[0048] Table 1 Note: In Table 1, -- means no compensation layer is set.

[0049] Comparative Example 1: Using the same raw materials as in Example 1, a thin film layer with a thickness of 3 μm was prepared by the prior art intelligent stripping method.

[0050] Comparative Example 2: Using the same raw materials as in Example 1, a thin film layer with a thickness of 3 μm was prepared by the prior art thinning and polishing method.

[0051] Comparison of the thin film layers prepared in Examples 1 to 6 with the thin film layers prepared in Comparative Examples 1 to 2 revealed the following results: (1) The embodiments can not only successfully prepare thin film layers with a thickness in the range of 1.5 μm to 5 μm, but also prepare thin film layers less than 1.5 μm and greater than 5 μm; moreover, the prepared thin film layers are very uniform, and the thickness deviation of the thin film layers prepared in all embodiments can be controlled within ±5%, and the non-uniformity of the thin film layers is less than 5%, which means that when the embodiments are used for the preparation of back-end devices, the impact on the performance indicators of the control device is very small.

[0052] (2) In Comparative Example 1, when preparing a single crystal composite thin film material of a lithium tantalate thin film layer with a thickness of 3 μm, if it is to be prepared by the intelligent stripping method, it is necessary to first simulate according to the SMRI software to obtain H + Ion implantation energy must exceed 400 KeV to achieve ion implantation with a depth of 3μm, but the energy of the ion implanter used for the smart stripping method in the prior art usually does not exceed 350KeV, so it is very difficult to meet the above requirements. In addition, the present invention also found that even if the depth of ion implantation can be achieved, it is difficult to achieve effective stripping due to the width limitation of ion dispersion, which will eventually lead to very poor uniformity of the thin film layer even if it is formed.

[0053] (3) In Comparative Example 2, the thinning and polishing method was used for preparation. The present invention adopts the process commonly used by existing domestic manufacturers for preparation. When the lithium tantalate is thinned to a thickness of 3 μm, the thickness deviation of the film exceeds 400 nm, and the non-uniformity of the film exceeds 10%, which is very unfavorable for the preparation of the back-end device and it is difficult to control the standardization and standardization of the device performance indicators.

[0054] (4) Based on the thinning and stripping method provided by the present invention, when preparing a single crystal composite thin film material with a thin film layer having a thickness of 1 to 5 μm, the film layer structure can be adjusted to effectively achieve the preparation of high-quality thin film materials as shown in Examples 1 to 6, without being affected by the type of material and the thickness of the film, thereby greatly expanding the application scenarios of the material.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a single crystal composite thin film material, characterized in that: The steps include: Step 1: Bonding the functional single crystal wafer and the substrate to form a bonded body; Step 2: Reduce the thickness of the functional single crystal wafer to a suitable range through a wafer thinning process; Step 3: Ion implantation is performed on one side surface of the functional single crystal wafer in the bonded body, so that a peeling layer, a damaged layer and a thin film layer are sequentially formed from the surface along its axial direction, and then the peeling layer and the thin film layer are separated from the damaged layer by annealing, and the remaining damaged layer and the thin film layer form an initial single crystal composite thin film material with the substrate; Step 4: removing the remaining damaged layer in the initial single crystal composite thin film material obtained in step 3 by a chemical mechanical polishing process, and then adjusting the uniformity of the functional single crystal thin film layer; Step 5: Repeat steps 3 to 4 to reduce the thickness of the thin film layer of the functional crystal to the target thickness, thereby obtaining the single crystal composite thin film material; wherein the thickness of the thin film layer is 0.1 to 100 μm.

2. The preparation method according to claim 1, characterized in that: The single crystal composite thin film material comprises a substrate, a surface of one side of the substrate having an oxide layer, and a functional single crystal thin film layer on the side of the oxide layer facing away from the substrate; or, the single crystal composite thin film material comprises a substrate, a surface of one side of the substrate having a compensation layer, a side of the compensation layer facing away from the substrate having an oxide layer, and a functional single crystal thin film layer on the side of the oxide layer facing away from the substrate.

3. The preparation method according to claim 2, characterized in that: The base substrate is selected from one of a silicon substrate, a silicon carbide substrate, a sapphire substrate, a gallium arsenide substrate, a gallium nitride substrate, an indium phosphide substrate, a spinel substrate, a diamond substrate, a quartz substrate, and an aluminum nitride substrate.

4. The preparation method according to claim 2, characterized in that: The thickness of the substrate is 0.1-5 mm.

5. The preparation method according to claim 2, characterized in that: The compensation layer is one of a silicon dioxide layer, a polysilicon layer, a silicon nitride layer, a gallium nitride layer, a gallium arsenide layer, and a Bragg reflection layer, and the thickness of the compensation layer is 0.1-15 μm.

6. The preparation method according to claim 2, characterized in that: The oxide layer is a silicon dioxide layer or a polymer layer, and the thickness of the oxide layer is 0.1-20 μm.

7. The preparation method according to claim 2, characterized in that: The functional single crystal wafer used in the functional single crystal thin film layer is selected from one of piezoelectric crystal, semiconductor crystal, ferroelectric crystal and laser crystal.

8. The preparation method according to claim 7, characterized in that: The component of the functional single crystal wafer is selected from one of lithium tantalate, lithium niobate, lead magnesium niobate-lead titanate, gallium arsenide, gallium oxide, gallium nitride, gallium carbide, indium phosphide, gallium phosphide, silicon carbide, aluminum nitride, zinc oxide, diamond, and yttrium aluminum garnet; the thickness of the thin film layer is 0.3~50μm.

9. The preparation method according to claim 2, characterized in that: A compensation layer is formed on the surface of the substrate by any one of chemical vapor deposition, physical vapor deposition, magnetron sputtering, liquid phase epitaxy, vapor phase epitaxy, and atomic layer deposition.

10. The preparation method according to claim 2, characterized in that: An oxide layer is formed on the surface of the substrate or on the surface of the compensation layer facing away from the substrate by any one of chemical vapor deposition, magnetron sputtering, thermal oxidation, spin coating, and scraping coating.

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