Diamond film and preparation method thereof
By forming a limiting portion on the sample table and the surface of the heterogeneous substrate and performing limiting fixation, the problem of heterogeneous substrate drift during the growth of the diamond film is solved, and high-quality growth of the diamond film is achieved.
Patent Information
- Application Number
- CN202411657200.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-04-04
AI Technical Summary
During the process of growing diamond films, heterogeneous substrates are prone to drift, resulting in uneven thickness, easy cracking and poor quality of diamond films.
By forming limiting parts on the surface of the sample table and the heterogeneous substrate, and using positioning members to cooperate with these limiting parts, limiting fixing between the sample table and the heterogeneous substrate is achieved. Subsequently, the hetero substrate after the limit fixation was subjected to chemical vapor deposition treatment to grow a diamond film.
It effectively avoids drifting of heterogeneous substrates, improves the temperature uniformity of the diamond film, reduces thermal stress, reduces the uneven thickness and cracking, and greatly improves the quality of the diamond film.
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Figure CN119753618A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing a diamond film and the diamond film. Background Art
[0002] As the heat dissipation material with the highest thermal conductivity, diamond has great application prospects in the field of semiconductor device heat dissipation in recent years due to its excellent thermal properties. Growing large-size diamond films has become the main research direction of workers in related fields.
[0003] However, due to the poor bonding force between the sample stage and the heterogeneous substrate, the heterogeneous substrate is prone to drift during the growth of diamond film, resulting in uneven thickness and easy cracking of the grown diamond film, resulting in poor quality of the prepared diamond film. Summary of the invention
[0004] The present invention provides a method for preparing a diamond film and a diamond film, aiming to solve the problems of uneven thickness, easy cracking and poor quality of the diamond film prepared by the related technology.
[0005] In a first aspect, the present invention provides a method for preparing a diamond film, the method comprising:
[0006] Prepare sample stage and foreign substrate;
[0007] A first limiting portion is formed on the surface of the sample stage, and a second limiting portion is formed on the surface of the heterogeneous substrate, wherein the first limiting portion and the second limiting portion are arranged correspondingly;
[0008] The positioning member cooperates with the first limiting portion and the second limiting portion to limit and fix the sample stage and the heterogeneous substrate;
[0009] The fixed and limited heterogeneous substrate is subjected to chemical vapor deposition treatment to grow a diamond film on a surface of the heterogeneous substrate away from the sample stage.
[0010] In a second aspect, the present invention provides a diamond film, wherein the diamond film is prepared by using the above-mentioned method for preparing a diamond film.
[0011] The present application provides a diamond film and a preparation method thereof, by preparing a sample stage and a heterogeneous substrate; forming a first limiting portion on the surface of the sample stage, and forming a second limiting portion on the surface of the heterogeneous substrate, the first limiting portion and the second limiting portion being arranged correspondingly; cooperating with the first limiting portion and the second limiting portion through a positioning member, so that the sample stage and the heterogeneous substrate are fixed in position; chemical vapor deposition is performed on the heterogeneous substrate after the position is fixed, so as to grow a diamond film on the surface of the heterogeneous substrate away from the sample stage. In this way, the limiting fixation of the sample stage and the heterogeneous substrate can be achieved, the situation that the heterogeneous substrate is prone to drift during the growth of the diamond film is avoided, the thermal conductivity of the heterogeneous substrate is improved, thereby improving the temperature uniformity of the diamond film, reducing the thermal stress between different positions, achieving rapid heat absorption of the diamond film, reducing the thermal expansion coefficient of the heterogeneous substrate, reducing the difference in the thermal expansion coefficient between the substrate and the diamond, reducing the growth temperature gradient of the diamond film, thereby reducing the stress inside the diamond, and then effectively reducing the situation that the diamond film has uneven thickness and is prone to cracking, and greatly improving the quality of the diamond film. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.
[0013] Figure 1 A schematic flow chart of the steps of a method for preparing a diamond film provided in an embodiment of the present application;
[0014] Figure 2 A schematic diagram of the structure of a sample stage and a blind hole on a heterogeneous substrate provided in an embodiment of the present application;
[0015] Figure 3 A schematic diagram of a structure for growing a diamond film on a heterogeneous substrate provided in an embodiment of the present application. DETAILED DESCRIPTION
[0016] The following 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0017] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.
[0018] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.
[0019] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.
[0020] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0021] As the heat dissipation material with the highest thermal conductivity, diamond has great application prospects in the field of semiconductor device heat dissipation due to its excellent thermal properties in recent years. The growth of diamond film has become the main research direction of workers in related fields. The preparation of diamond is mainly achieved through chemical vapor deposition (CVD) technology, and its material preparation cost is also high. Therefore, it is necessary to prepare larger-sized diamond films to reduce the cost of single chips (die).
[0022] However, there are still some technical difficulties in preparing large-sized diamond films, such as large warping of large-sized diamond films, easy cracking during growth or subsequent processing, and uneven thickness of large-sized diamond films. The existing preparation process of diamond films generally uses CVD technology to deposit them on a foreign substrate, and then removes the foreign substrate. Commonly used substrates include Mo substrates and Si substrates. During the cooling process, due to the difference in thermal expansion coefficients between diamond and substrate (diamond is 1.2*10 -6 m / K, Mo is 6*10 -6 m / K, Si is 3.5*10 -6 m / K) is large, which will produce large thermal residual stress, which is easy to cause cracking or breaking of diamond film. Another major problem in the preparation process of diamond film is the uneven thickness of large-sized diamond film.
[0023] Among them, the main reason for cracking is that diamond is deposited at high temperature, and there is a large residual stress inside. This residual stress is the sum of thermal stress and intrinsic stress. Thermal stress is mainly caused by the difference in thermal expansion coefficient between diamond and substrate. The main reason for the uneven thickness of diamond film is the difference in temperature gradient at the growth front of diamond. For brittle material diamond, the internal stress caused by temperature gradient may also make the material more prone to breakage or fracture when subjected to external force.
[0024] To solve the above problems, the present application provides a diamond film and a preparation method thereof, which can realize the limited fixation of the sample stage and the heterogeneous substrate, avoid the drift of the heterogeneous substrate during the growth of the diamond film, thereby realizing rapid heat equalization of the diamond film, reducing the growth temperature gradient of the diamond film, greatly reducing the internal stress, and effectively reducing the uneven thickness and easy cracking of the diamond film, thereby greatly improving the quality of the diamond film.
[0025] See also Figure 1 , Figure 1 The present invention provides a schematic flow chart of a method for preparing a diamond film according to an embodiment of the present invention. The method for preparing a diamond film can realize the limiting fixation of the sample stage and the heterogeneous substrate, avoiding the situation that the heterogeneous substrate is prone to drift during the growth of the diamond film, thereby realizing the rapid heat equalization of the diamond film, reducing the growth temperature gradient of the diamond film, greatly reducing the internal stress, and further effectively reducing the situation that the diamond film has uneven thickness and is prone to cracking, thereby greatly improving the quality of the diamond film.
[0026] like Figure 1 As shown, the method for preparing the diamond film includes: step S101 to step S104.
[0027] S101, preparing a sample stage and a heterogeneous substrate.
[0028] The sample stage can be used as a base to prepare diamond thin films, which can be prepared from materials with high dimensional accuracy and high heat dissipation capacity. The heterogeneous substrate can be used to grow diamond thin films, which can be prepared from materials with high thermal conductivity and low thermal expansion coefficient.
[0029] In some embodiments, the sample stage is prepared by a first thermally conductive material, the thermal conductivity of the first thermally conductive material is 500-800 W / (mK), and the thermal expansion coefficient of the first thermally conductive material is less than 10×10 -6 m / K; according to the size of the diamond film to be prepared, a heterogeneous substrate is prepared by a second thermally conductive material, the thermal conductivity of the second thermally conductive material is greater than or equal to 100W / (mK), and the thermal expansion coefficient of the second thermally conductive material is less than 10×10 -6m / K. Thus, a sample stage and a heterogeneous substrate with high thermal conductivity can be prepared by limiting the thermal conductivity and thermal expansion coefficient of the first thermally conductive material and the second thermally conductive material.
[0030] Exemplarily, the thermal conductivity of the first thermally conductive material is 500-800 W / (mK), and the thermal expansion coefficient of the first thermally conductive material is less than 10×10 -6 m / K, so the first thermally conductive material can be selected from any one of diamond aluminum, graphite aluminum composite material, copper, silicon carbide and diamond.
[0031] Exemplarily, the thermal conductivity of the second thermally conductive material is greater than or equal to 100 W / (mK), and the thermal expansion coefficient of the second thermally conductive material is less than 10×10 -6 m / K, so the second thermally conductive material can be selected from any one of silicon carbide, silicon, diamond, graphite, and boron nitride.
[0032] Exemplarily, the second thermally conductive material can be selected from a material with a thermal expansion coefficient close to that of diamond, such as a diamond-copper composite material, so that the difference in thermal expansion coefficients between diamond and the substrate is smaller, reducing the thermal residual stress that will be generated, thereby effectively avoiding cracking or breakage of the subsequently prepared diamond film.
[0033] Since the heterogeneous substrate needs to have a high heat-averaging ability and a low thermal expansion coefficient, thereby reducing the temperature gradient during the diamond growth process and improving the thickness uniformity of the subsequently prepared diamond film, the present invention proposes to replace the molybdenum substrate with a material with high thermal conductivity and low thermal expansion coefficient, such as a diamond-copper composite material, which can reduce the difference in thermal expansion coefficient between the diamond and the heterogeneous substrate, thereby reducing the stress accumulation during the growth and cooling process, greatly improving the lateral thermal conductivity, and also effectively avoiding the warping of the diamond film.
[0034] It should be noted that by selecting the above-mentioned first thermally conductive material and second thermally conductive material to prepare the sample stage and the heterogeneous substrate, the sample stage and the heterogeneous substrate can both have the characteristics of high thermal conductivity and low thermal expansion coefficient, thereby having high dimensional accuracy and high heat dissipation capacity.
[0035] For example, the diamond copper composite material can be prepared by hot pressing infiltration. The thermal conductivity of the prepared diamond copper composite material is 800 W / (mK) and the thermal expansion coefficient is 4*10 -6 m / K, and the diamond copper composite material is used to process the sample stage, and the thickness of the sample stage can be controlled to 20mm; the diamond copper composite material is used to process the heterogeneous substrate, and the thickness of the heterogeneous substrate can be controlled to 10mm.
[0036] It should be noted that the thickness of the sample stage and the heterogeneous substrate can be determined according to the size of the diamond film to be prepared. Generally, the thicker the diamond film is, the smaller its warping deformation is.
[0037] S102, forming a first limiting portion on the surface of the sample stage, and forming a second limiting portion on the surface of the heterogeneous substrate, the first limiting portion and the second limiting portion being arranged correspondingly.
[0038] The first limiting portion and the second limiting portion can be blind holes, grooves, etc., which can cooperate with the positioning member. The first limiting portion and the second limiting portion are arranged correspondingly so as to achieve limiting cooperation with the positioning member at the same time.
[0039] In some embodiments, the surface of the sample stage is punched to form at least one blind hole; the surface of the heterogeneous substrate is punched to form at least one blind hole; wherein the blind hole parameters of the sample stage are the same as the blind hole parameters of the heterogeneous substrate.
[0040] Exemplarily, a specific position on the surface of the sample stage can be punched to form at least one blind hole on the surface of the sample stage as a first limiting portion; a specific position on the surface of the heterogeneous substrate can be punched to form at least one blind hole on the surface of the heterogeneous substrate as a second limiting portion, and at the same time, the blind hole parameters of the blind holes on the surface of the sample stage are controlled to be the same as the blind hole parameters of the blind holes on the surface of the heterogeneous substrate.
[0041] like Figure 2 As shown, the sample stage and the heterogeneous substrate are punched, and 5 blind holes are formed on the surface of the sample stage and the surface of the heterogeneous substrate respectively, which are symmetrically distributed, wherein the diameter of the blind hole is 3 mm and the depth of the blind hole is 2 mm.
[0042] It should be noted that at least the blind hole positions of the blind holes on the sample stage surface need to be controlled to be the same as the blind hole positions of the blind holes on the surface of the heterogeneous substrate, so that each blind hole on the sample stage surface corresponds to each blind hole on the surface of the heterogeneous substrate one by one to achieve limit matching.
[0043] Specifically, the blind hole parameters may include the number of blind holes, the positions of the blind holes and the size of the blind holes, and the blind hole size includes the diameter of the blind holes and the depth of the blind holes. The number of blind holes, the positions of the blind holes and the size of the blind holes on the surface of the sample stage are the same as the number of blind holes, the positions of the blind holes and the size of the blind holes on the surface of the heterogeneous substrate, so that the first limiting part and the second limiting part can better achieve limiting cooperation.
[0044] Exemplarily, the blind hole size includes a blind hole diameter and a blind hole depth, the blind hole diameter is d, the blind hole depth of the sample stage is h1, the blind hole depth of the heterogeneous substrate is h2, the thickness of the sample stage is h3, and the thickness of the heterogeneous substrate is h4;
[0045] Among them, 0.1mm≤d≤20mm, h1 <h3,h2<h4。
[0046] By controlling the diameter and depth of the blind hole, the first limiting portion and the second limiting portion can better achieve limiting cooperation.
[0047] S103 , the positioning member cooperates with the first limiting portion and the second limiting portion to limit and fix the sample stage and the heterogeneous substrate.
[0048] The positioning member can cooperate with the first limiting portion and the second limiting portion at the same time, so that the sample stage and the heterogeneous substrate are limited and fixed.
[0049] In some embodiments, before the sample stage and the heterogeneous substrate are limited and fixed by cooperating with the first limiting portion and the second limiting portion through the positioning member, the surface of the sample stage and the surface of the heterogeneous substrate are chemically mechanically polished; the back side of the heterogeneous substrate where the second limiting portion is formed is cleaned and etched.
[0050] Exemplarily, the two surfaces of the sample stage can be chemically mechanically polished so that the roughness Ra of the two surfaces of the sample stage is less than 0.1 microns, and then the surface of the heterogeneous substrate (the surface with the blind hole formed) is chemically mechanically polished so that the roughness Ra of the surface is less than 0.1 microns.
[0051] Specifically, the back side (the side used for growing the diamond film, ie, the diamond seed layer) of the heterogeneous substrate on which the second limiting portion is formed may be cleaned and etched.
[0052] Exemplarily, the diamond seed layer can be placed in a heated dilute acid for treatment. Dilute acid is usually prepared by mixing nitric acid, concentrated sulfuric acid and water in a certain ratio (such as 3:1:5 or concentrated nitric acid: concentrated sulfuric acid = 3:1) to remove metal impurities and other contaminants remaining on the surface of the heterogeneous substrate to reduce the impact on diamond growth. Then, the diamond seed layer is alternately ultrasonically cleaned using acetone, anhydrous ethanol and deionized water. The cleaning time and power of each solvent can be adjusted according to the specific situation to ensure the cleaning effect, so that organic matter and other residues on the surface of the diamond seed layer can be further removed to ensure the cleanliness of the surface. Finally, the cleaned diamond seed layer is placed in a cavity for hydrogen-oxygen plasma etching. Parameters such as etching time and power need to be adjusted according to the specific situation to ensure the etching effect, so that defects and damage on the surface of the diamond seed layer can be etched away, the surface roughness can be reduced, and the growth surface is more conducive to diamond epitaxial growth.
[0053] In some embodiments, the sample stage, the positioning member and the heterogeneous substrate are placed on the water-cooling stage in sequence, and the positioning member is engaged with the first limiting portion and the second limiting portion.
[0054] Specifically, the sample stage can be placed on a water-cooled stage, and the positioning member cooperates with the first limiting portion, and then cooperates with the second limiting portion, so that the heterogeneous substrate is fixedly placed on the sample stage and the limiting cooperation can be well achieved.
[0055] Exemplarily, the positioning member can be a positioning pin, one end of which can be placed in the blind hole of the sample stage, and the other end of which can be placed in the blind hole of the heterogeneous substrate, so that the positioning pin can connect the sample stage and the heterogeneous substrate and achieve limit fit.
[0056] It should be noted that the number of positioning elements is generally consistent with the number of blind holes, so that the sample stage and the heterogeneous substrate can better achieve limited fit.
[0057] In some embodiments, the thermal expansion coefficient of the positioning member is greater than or equal to the thermal expansion coefficient of the first thermally conductive material and the second thermally conductive material, the first thermally conductive material is the material of the sample stage, and the second thermally conductive material is the material of the heterogeneous substrate.
[0058] Specifically, it is necessary to control the thermal expansion coefficient of the material used to prepare the positioning piece to be greater than or equal to the thermal expansion coefficient of the first heat-conducting material, and greater than or equal to the thermal expansion coefficient of the second heat-conducting material.
[0059] For example, when the subsequent chemical vapor deposition process is heated to the diamond growth temperature, assuming that the material of the positioning pin is copper, and the first thermal conductive material and the second thermal conductive material are diamond-copper composite materials, since the thermal expansion coefficient of copper is greater than or equal to the thermal expansion coefficient of the diamond-copper composite material, the positioning pin will expand in volume at this time, and the expansion speed and expansion range of the positioning pin are greater than the sample stage and the heterogeneous substrate, so that the positioning pin is in close contact with the sample stage and the heterogeneous substrate, thereby achieving limited fixation of the sample stage and the heterogeneous substrate, avoiding the situation where the heterogeneous substrate is prone to drift during the growth of diamond film.
[0060] In some embodiments, the thermal conductivity of the positioning member is greater than or equal to 100 W / (mK).
[0061] For example, when the subsequent chemical vapor deposition process is heated to the diamond growth temperature, assuming that the material of the positioning pin is copper, due to the high thermal conductivity of copper, the positioning pin can also increase the heat conduction between the heterogeneous substrate and the sample stage, thereby achieving efficient heat uniformity, reducing the temperature gradient during the diamond growth process, and improving the lateral thermal conductivity, thereby improving the thickness uniformity of the diamond film.
[0062] S104, performing chemical vapor deposition on the position-fixed heterogeneous substrate to grow a diamond film on the surface of the heterogeneous substrate away from the sample stage.
[0063] In some embodiments, the sample stage, the positioning member and the heterogeneous substrate that have been limited and fixed are placed in a chemical vapor deposition device and heated to a deposition temperature; after the chemical vapor deposition device is heated to the deposition temperature, the positioning member expands to allow the sample stage, the positioning member and the heterogeneous substrate to fit together.
[0064] The deposition temperature is the temperature required for deposition. Chemical vapor deposition may include hot filament chemical vapor deposition (HFCVD), microwave plasma chemical vapor deposition (MPCVD), etc., which are not specifically limited here.
[0065] like Figure 3 As shown, exemplarily, the sample stage, the positioning member and the heterogeneous substrate after being limited and fixed are placed in a chemical vapor deposition device for hot-wire chemical vapor deposition. After the chemical vapor deposition device is heated to the deposition temperature, since the thermal expansion coefficient of the positioning member is greater than or equal to the thermal expansion coefficient of the sample stage, the positioning pin will expand in volume at this time, so that the positioning pin is in close contact with the sample stage and the heterogeneous substrate, thereby achieving limited fixation of the sample stage and the heterogeneous substrate, avoiding the situation where the heterogeneous substrate is prone to drift during the growth of the diamond film, and finally a diamond film of uniform thickness and high quality can be grown on the surface of the heterogeneous substrate away from the sample stage.
[0066] The present application provides a method for preparing a diamond film, which comprises preparing a sample stage and a heterogeneous substrate; forming a first limiting portion on the surface of the sample stage, and forming a second limiting portion on the surface of the heterogeneous substrate, wherein the first limiting portion and the second limiting portion are arranged correspondingly; cooperating with the first limiting portion and the second limiting portion through a positioning member, so that the sample stage and the heterogeneous substrate are fixed in position; and chemical vapor deposition is performed on the heterogeneous substrate after the position is fixed, so that a diamond film is grown on the surface of the heterogeneous substrate away from the sample stage. Thus, the position fixing of the sample stage and the heterogeneous substrate can be achieved, the situation that the heterogeneous substrate is prone to drift during the growth of the diamond film is avoided, the thermal conductivity of the heterogeneous substrate is improved, thereby improving the temperature uniformity of the diamond film, reducing the thermal stress between different positions, achieving rapid heat absorption of the diamond film, reducing the thermal expansion coefficient of the heterogeneous substrate, reducing the difference in the thermal expansion coefficient between the substrate and the diamond, reducing the growth temperature gradient of the diamond film, thereby reducing the stress inside the diamond, and then effectively reducing the situation that the diamond film has uneven thickness and is prone to cracking, and greatly improving the quality of the diamond film.
[0067] The following is a specific example to illustrate the method for preparing the diamond film of the embodiment of the present application.
[0068] (1) A diamond copper composite material was prepared by hot pressing and infiltration. The thermal conductivity of the prepared diamond copper composite material was 800 W / (mK) and the thermal expansion coefficient was 4*10-6 m / K, and the diamond copper composite material is used to process the sample stage, and the thickness of the sample stage is determined according to the size of the diamond film to be prepared, and the thickness of the sample stage is 20 mm;
[0069] (2) Processing the diamond copper composite material into a heterogeneous substrate, and determining the thickness of the heterogeneous substrate according to the size of the diamond film to be prepared, for example, 10 mm;
[0070] (3) Blind holes are processed on the sample stage and the heterogeneous substrate. The number of blind holes is 5 and they are symmetrically distributed. The diameter of the blind holes is 3 mm and the depth of the blind holes is 2 mm.
[0071] (4) Chemically and mechanically polish the upper and lower surfaces of the diamond copper sample stage to a roughness Ra of < 0.1 μm.
[0072] (5) Chemical mechanical polishing is performed on the reverse side of the diamond surface grown on the heterogeneous substrate, and the roughness Ra is less than 0.1 micron.
[0073] (6) Cleaning and etching the diamond growth surface of the heterogeneous substrate;
[0074] (7) Aligning the sample stage, the positioning pin and the heterogeneous substrate in sequence on a water-cooled table, the sample stage is placed in the HFCVD chamber to start diamond growth, thereby growing a diamond film on the surface of the heterogeneous substrate away from the sample stage.
[0075] An embodiment of the present application further provides a diamond film, which is prepared by using the method for preparing a diamond film provided by any of the above embodiments.
[0076] The specific method of preparing the diamond film can refer to the corresponding embodiment recorded in the specification of this application, and this embodiment will not be repeated here. The diamond film provided in the embodiment of this application has no cracks, uniform thickness and high quality.
[0077] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.
Claims
1. A method for preparing a diamond film, characterized in that: The method comprises: Prepare sample stage and foreign substrate; A first limiting portion is formed on the surface of the sample stage, and a second limiting portion is formed on the surface of the heterogeneous substrate, wherein the first limiting portion and the second limiting portion are arranged correspondingly; The positioning member cooperates with the first limiting portion and the second limiting portion to limit and fix the sample stage and the heterogeneous substrate; The fixed and limited heterogeneous substrate is subjected to chemical vapor deposition treatment to grow a diamond film on a surface of the heterogeneous substrate away from the sample stage.
2. The preparation method according to claim 1, characterized in that: The method of preparing a sample stage and a heterogeneous substrate comprises: The sample stage is prepared by a first heat-conducting material, wherein the thermal conductivity of the first heat-conducting material is 500-800 W / (mK), and the thermal expansion coefficient of the first heat-conducting material is less than 10×10 -6 m / K; According to the size of the diamond film to be prepared, a heterogeneous substrate is prepared by using a second thermally conductive material, wherein the thermal conductivity of the second thermally conductive material is greater than or equal to 100 W / (mK), and the thermal expansion coefficient of the second thermally conductive material is less than 10×10 -6 m / K.
3. The preparation method according to claim 1, characterized in that: The method of forming a first limiting portion on the surface of the sample stage and forming a second limiting portion on the surface of the heterogeneous substrate includes: Punching the surface of the sample stage to form at least one blind hole; Performing a drilling process on the surface of the heterogeneous substrate to form at least one blind hole; The blind hole parameters of the sample stage are the same as the blind hole parameters of the heterogeneous substrate.
4. The preparation method according to claim 3, characterized in that: The blind hole parameters include the number of blind holes, the position of blind holes and the size of blind holes; The blind hole size includes a blind hole diameter and a blind hole depth, the blind hole diameter is d, the blind hole depth of the sample stage is h1, the blind hole depth of the heterogeneous substrate is h2, the thickness of the sample stage is h3, and the thickness of the heterogeneous substrate is h4; Among them, 0.1mm≤d≤20mm, h1 <h3,h2<h4。 5. The preparation method according to claim 1, characterized in that: Before the positioning member cooperates with the first limiting portion and the second limiting portion to limit and fix the sample stage and the heterogeneous substrate, the method further includes: Performing chemical mechanical polishing on the surface of the sample stage and the surface of the heterogeneous substrate; The back side of the heterogeneous substrate where the second limiting portion is formed is cleaned and etched.
6. The preparation method according to claim 1, characterized in that: The positioning member cooperates with the first limiting portion and the second limiting portion to limit and fix the sample stage and the heterogeneous substrate, including: The sample stage, the positioning member and the heterogeneous substrate are sequentially placed on the water-cooling stage, and the positioning member is engaged with the first limiting portion and the second limiting portion.
7. The preparation method according to claim 1, characterized in that: The step of performing chemical vapor deposition on the position-limited and fixed heterogeneous substrate comprises: Placing the sample stage, the positioning member and the heterogeneous substrate after being limited and fixed in a chemical vapor deposition device, and heating them to a deposition temperature; After the chemical vapor deposition device is heated to the deposition temperature, the positioning member expands to allow the sample stage, the positioning member and the heterogeneous substrate to fit together.
8. The preparation method according to any one of claims 1 to 7, characterized in that: The thermal expansion coefficient of the positioning member is greater than or equal to the thermal expansion coefficient of a first thermally conductive material and a second thermally conductive material, the first thermally conductive material is the material of the sample stage, and the second thermally conductive material is the material of the heterogeneous substrate.
9. The preparation method according to any one of claims 1 to 7, characterized in that: The thermal conductivity of the positioning member is greater than or equal to 100 W / (mK).
10. A diamond film, characterized in that: The diamond thin film is prepared by using the method for preparing a diamond thin film according to any one of claims 1 to 9.