Matrix structure for growing diamond film and preparation method of diamond film

Abstract

The invention relates to a matrix structure for growing a diamond film and a preparation method of the diamond film, the matrix structure comprises a substrate, a buffer layer, a heat conduction layer and a heat conduction substrate, the material of the substrate comprises graphite; the buffer layer covers at least part of the surface of the substrate; the buffer layer is provided with a first surface and a second surface which are oppositely arranged, the first surface comprises a growth surface, the second surface comprises a heat conduction surface, and the growth surface is used for growing a diamond film. The heat-conducting layer is arranged on the heat-conducting surface. The melting point of the heat conduction layer is not higher than the melting point of the heat conduction substrate and the melting point of the buffer layer. The matrix structure is rapid in heat transfer, relatively uniform in temperature, small in thermal stress, free of film cracking during growth of the diamond film, good in growth quality and capable of achieving a relatively large thickness.

Description

Technical Field

[0001] The invention relates to the field of diamond materials, and in particular to a substrate structure for growing a diamond film and a method for preparing the diamond film. Background Art

[0002] In modern optical applications, extremely stringent requirements are placed on the optical properties and environmental stability of materials. Traditional materials, such as glass and plastic, are limited in their application in special optical environments such as high-energy lasers, high-temperature environments, and highly corrosive media due to their inherent scattering, absorption characteristics, and low chemical resistance.

[0003] Diamond stands out for its exceptional hardness, high transmittance, low scattering and excellent chemical resistance, making it one of the best materials to meet the needs of demanding optical environments.

[0004] In the traditional method, when preparing thicker diamond films, the thermal stress will be large due to the uneven temperature between the diamond and the substrate and the long duration of the temperature difference, making the prepared diamond film prone to cracks, poor optical properties, inability to achieve self-support, poor quality, and low preparation yield. Summary of the invention

[0005] In view of this, the present invention proposes a substrate structure for growing a diamond film and a method for preparing a diamond film, aiming to present a substrate structure that can grow a diamond film with good thermal conductivity, and obtain a diamond film with excellent performance through the above-mentioned substrate structure, so as to solve the problems of poor performance and low preparation yield of diamond films in the prior art.

[0006] The first aspect of the present invention provides a matrix structure for growing a diamond film, comprising: a substrate, the material of the substrate comprising graphite; a buffer layer, the buffer layer covering at least a portion of the surface of the substrate; the buffer layer having a first surface and a second surface arranged opposite to each other, the first surface comprising a growth surface, the second surface comprising a heat-conducting surface, the growth surface being used to grow a diamond film; a heat-conducting layer, the heat-conducting layer being arranged on the heat-conducting surface; and a heat-conducting substrate, the heat-conducting substrate being arranged on a side of the heat-conducting layer away from the buffer layer, the melting point of the heat-conducting layer being no higher than the melting point of the heat-conducting substrate and the melting point of the buffer layer.

[0007] It can be seen from the above technical scheme that the substrate structure for growing diamond film proposed in the first aspect of the present invention has good thermal conductivity of the substrate itself; the buffer layer covers the substrate to protect the substrate, improve the support stability of the substrate, and isolate the graphite in the substrate to prevent the graphite from polluting the growth environment of the diamond film; the growth surface of the buffer layer is used to grow the diamond film, and the heat on the growth surface can be quickly transferred to the substrate. In addition, since the entire heat-conducting surface of the buffer layer is in stable contact with the heat-conducting layer, and the side of the heat-conducting layer away from the buffer layer is stably connected to the heat-conducting substrate, heat can be quickly conducted between the layers of the structure during the growth of the diamond film on the buffer layer, and the temperature of the entire substrate structure is relatively uniform, and there will be no sudden temperature change on the interface. The diamond film on the growth surface can reach a certain thickness during growth, and the diamond film does not crack, and the growth quality is good. The melting point of the heat-conducting layer is not higher than the melting point of the heat-conducting substrate and the melting point of the buffer layer, so that in the process of forming the entire substrate structure, the heat-conducting layer can melt before other layers at a preset temperature and stably connect between the buffer layer and the heat-conducting substrate.

[0008] The second aspect of the present invention provides a method for preparing a diamond film, which is used for preparing a diamond film. The method comprises the following steps: providing a substrate; preparing a buffer layer covering at least part of the surface of the substrate; providing a heat-conducting substrate and providing a metal layer plate used for preparing the heat-conducting layer, placing the metal layer plate between the buffer layer and the heat-conducting substrate to form a preparatory body; placing the preparatory body in a vacuum chamber, heating the preparatory body by hydrogen plasma, raising the temperature in the vacuum chamber to 1100°C to 1300°C, waiting for the metal layer plate to melt between the heat-conducting substrate and the buffer layer, cooling the metal layer plate to form a heat-conducting layer, and taking it out as a base structure; washing the base structure with a lotion The invention relates to a method for preparing a substrate structure, comprising the steps of: cleaning; ultrasonically treating the substrate in deionized water for 10 to 60 minutes; drying the substrate structure, and surface treating the substrate structure with oxygen plasma and / or ozone atmosphere; preparing a diamond particle suspension, ultrasonically treating the substrate structure in the diamond particle suspension for 10 to 60 minutes, drying and forming a substrate structure with diamond seeds on the surface of the substrate structure; placing the substrate structure with the diamond seeds in a chemical vapor deposition device, evacuating the substrate structure to below 0.001 Pa, introducing a mixed gas of methane, hydrogen and oxygen as a reaction gas, and depositing a diamond film on the growth surface of the substrate structure; and removing the substrate structure to obtain a diamond film.

[0009] It can be seen from the above technical scheme that the preparation method of the diamond film proposed in the second aspect of the present invention is that during the preparation process, the temperature of the metal layer in the vacuum chamber reaches 1100℃~1300℃, and the melting point of the metal layer can be exceeded to achieve melting, so that the metal layer is melted into a thermal conductive layer and the thermal conductive substrate and the buffer layer are connected, and the connection performance between the three is good and the temperature transfer is fast. During the entire preparation process, the heat conduction between the buffer layer, substrate, thermal conductive layer, and thermal conductive substrate is uniform and fast, so that during the growth process of the diamond film, the temperature difference is small, the temperature uniformity is high, no sudden changes occur, and it is not easy to break due to thermal stress concentration. The prepared diamond film is of high quality, large thickness, and high yield.

[0010] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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 like these accompanying drawings without paying any creative work.

[0012] Figure 1 is a schematic diagram of a substrate structure for growing a diamond film on a growth surface proposed in some embodiments of the present invention, wherein the buffer layer is a single material layer;

[0013] Figure 2 is a schematic diagram of a substrate structure for growing a diamond film on a growth surface proposed in some embodiments of the present invention, wherein the buffer layer is a structure in which multiple layers of materials are alternately arranged;

[0014] Figure 3 is a schematic diagram of a substrate structure for growing a diamond film on a growth surface proposed in some embodiments of the present invention, wherein the buffer layer is a structure in which the mass content of each material varies in a gradient in each layer;

[0015] Figure 4 It is a schematic diagram of a substrate structure for growing a diamond film proposed in some embodiments of the present invention, wherein a diamond film is grown on a growth surface and placed on a deposition base, wherein a heat-saturating groove is provided on the heat-conducting base;

[0016] Figure 5 yes Figure 4 Bottom view of the substrate structure used to grow diamond film.

[0017] Figure 6is a bottom view of a substrate structure for growing a diamond film according to some embodiments of the present invention, wherein a heat-saturating hole is provided on the heat-conducting substrate;

[0018] Figure 7 It is a schematic diagram of a substrate structure for growing a diamond film proposed in some embodiments of the present invention, which is placed on a deposition base to grow a diamond film on a growth surface, wherein a transition layer is provided between the buffer layer and the heat conducting layer;

[0019] Figure 8 1 is a schematic flow chart of each step of a method for preparing a diamond film according to some embodiments of the present invention;

[0020] Fig. 9 It is a schematic diagram of the structure after the main steps in the method for preparing the diamond film of some embodiments of the present invention are processed.

[0021] Fig.10 is a SEM test image of the diamond film according to the first embodiment of the present invention;

[0022] Fig.11 is the XRD spectrum of the diamond film of Example 1 of the present invention;

[0023] Fig.12 is a Raman spectrum data diagram of the diamond film according to the first embodiment of the present invention;

[0024] Fig.13 is a SEM test image of the diamond film of Example 2 of the present invention;

[0025] Fig.14 is the XRD spectrum of the diamond film of Example 2 of the present invention;

[0026] Fig.15 This is a Raman spectrum data diagram of the diamond film according to the second embodiment of the present invention.

[0027] Fig.16 It is a schematic diagram of the relationship between the thermal expansion coefficient and thermal conductivity of each material used in the present invention.

[0028] Description of reference numerals:

[0029] 100. Matrix structure;

[0030] 10. Substrate;

[0031] 20. Buffer layer; 21. Growth surface; 22. Heat conduction surface;

[0032] 201, first gradient layer; 202, second gradient layer; 203, third gradient layer;

[0033] 40. Transition layer;

[0034] 50. heat conducting layer; 51. metal layer plate;

[0035] 60. thermal conductive substrate; 61. heat-saturating structure; 611. heat-saturating hole; 612. heat-saturating groove;

[0036] 200, deposition base;

[0037] 300. Diamond film; 310. Diamond seed crystal. DETAILED DESCRIPTION

[0038] 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, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0039] In the absence of conflict, the following embodiments and features of the embodiments may be combined with each other.

[0040] like Figure 1 As shown, an embodiment of the present invention provides a base structure 100 for growing a diamond film 300 , including: a substrate 10 , a buffer layer 20 , a heat-conducting layer 50 and a heat-conducting substrate 60 .

[0041] The material of the substrate 10 includes graphite, that is, the substrate 10 has the characteristics brought by graphite due to its graphite material, such as high thermal conductivity of graphite, low thermal expansion coefficient of graphite, and high melting point of graphite, which can bring corresponding characteristics to the substrate 10.

[0042] Furthermore, the buffer layer 20 is coated on at least a portion of the surface of the substrate 10, where the surface of the substrate 10 includes the upper surface, the lower surface and the side surface of the substrate 10. The buffer layer 20 can completely wrap the entire substrate 10, that is, the buffer layer 20 is arranged on the entire circumference of the substrate 10; the buffer layer 20 can also wrap the upper surface and the side surface of the substrate 10.

[0043] Continue to refer to Figure 1 The buffer layer 20 has a first surface and a second surface that are arranged opposite to each other, the first surface includes a growth surface 21, and the second surface includes a heat conduction surface 22. For example, when the first surface of the buffer layer 20 is the upper surface and the second surface is the lower surface, the upper surface of the buffer layer 20 can be used as the growth surface 21, and the lower surface of the buffer layer 20 is used as the heat conduction surface 22, and the growth surface 21 is used to grow the diamond film 300. The diamond film 300 here has a certain thickness. In the present invention, the thickness of the diamond film 300 is 0.05 mm to 4 mm; more advantageously, it is controlled to be 0.5 mm to 2 mm.

[0044] Furthermore, the heat conducting layer 50 is disposed on the heat conducting surface 22 . The heat conducting substrate 60 is disposed on a side of the heat conducting layer 50 away from the buffer layer 20 , and the melting point of the heat conducting layer 50 is not higher than the melting points of the heat conducting substrate 60 and the buffer layer 20 .

[0045] As can be seen from the above technical solution, the base structure 100 for growing the diamond film 300 proposed by the present invention, the substrate 10 includes graphite. Due to the characteristics of graphite, the substrate 10 itself has good thermal conductivity and low thermal expansion coefficient, fast heat transfer, and is convenient for subsequent mechanical grinding and removal. It can resist thermal expansion and thermal shock and provide excellent support, providing a basic support with excellent performance for the growth of the diamond film 300 to prevent the structure from collapsing in a high-temperature environment.

[0046] Since the substrate 10 made of graphite is not wear-resistant and can be easily scratched, the buffer layer 20 covering the substrate 10 can protect the substrate 10, improve the support stability of the substrate 10, and isolate the graphite in the substrate 10 to prevent the graphite from contaminating the growth environment of the diamond film 300.

[0047] The growth surface 21 of the buffer layer 20 is used to grow the diamond film 300. The heat on the growth surface 21 can be quickly transferred to the substrate 10, and the substrate 10 further transfers the heat to the buffer layer 20 on the bottom side of the substrate 10 and further transfers the heat to other layer structures. The temperature of the buffer layer 20 itself can also be quickly transferred to the heat-conducting layer 50 and the heat-conducting substrate 60.

[0048] In the present application, the melting point of the thermal conductive layer 50 is not higher than the melting point of the thermal conductive substrate 60 and the melting point of the buffer layer 20, so that in the process of forming the entire base structure 100, the thermal conductive layer 50 can melt before other layers at a preset temperature and stably connect between the buffer layer 20 and the thermal conductive substrate 60, thereby forming a stable multi-layer structure, and the layers are tightly connected, reducing the interface thermal stress between the layers.

[0049] Then, in the above-mentioned tightly connected base structure 100, the entire heat-conducting surface 22 of the buffer layer 20 is in stably contact with the heat-conducting layer 50, and the side of the heat-conducting layer 50 away from the buffer layer 20 is stably connected to the heat-conducting substrate 60, so that in the process of growing the diamond film 300 on the buffer layer 20, heat can be quickly conducted between the various layer structures, and the temperature of the entire base structure 100 is relatively uniform, and there will be no sudden temperature change on the interface. Therefore, the diamond film 300 located on the growth surface 21 can reach a certain thickness during growth, and the diamond film 300 does not crack, the growth quality is good, and the preparation yield is high.

[0050] It is understandable that compared with the defect of the prior art that a diamond film 300 with great thickness and excellent performance cannot be prepared, the diamond film 300 in the base structure 100 for growing the diamond film 300 of the present invention can achieve great thickness and high film quality.

[0051] It should be noted that the diamond film 300 of the present invention mainly refers to the portion grown on the upper surface of the buffer layer 20. In some examples, even if some diamond film 300 is grown on the side of the buffer layer 20, the thickness of the diamond film 300 located on the side is not counted, and only the thickness of the diamond film 300 grown on the upper surface of the buffer layer 20 is counted, that is, the thickness of the diamond film 300 described in this application.

[0052] It should also be noted that the terms "up" and "down" in the present invention are relative concepts, with the direction from the heat-conducting substrate 60, the heat-conducting layer 50, the heat-conducting surface 22, the substrate 10, and the growth surface 21 being the up direction, and the direction from the growth surface 21, the substrate 10, the heat-conducting surface 22, the heat-conducting layer 50, and the heat-conducting substrate 60 being the down direction. However, the terms "up" and "down" should not be construed as limiting the scope of the present application, but should be construed as being for the convenience of explaining the relative positional relationship.

[0053] Optionally, the thickness of the diamond film 300 is 0.05 mm to 4 mm. When the thickness of the diamond film 300 is too thick, its deposition cost is too high, the yield rate is reduced, and the preparation process is difficult; when the thickness of the diamond film 300 is too thin, the comprehensive cost consumed in the preparation is too high, the cost performance is low, and it is not conducive to the subsequent grinding process. Therefore, when the thickness of the above-mentioned diamond film 300 is controlled within the above-mentioned range, the deposition cost is controlled within a reasonable range, the finished product yield is high, and the comprehensive cost is controlled within a reasonable range. Advantageously, the thickness of the diamond film 300 is 0.5 mm to 2 mm, which can be more conducive to achieving the aforementioned performance.

[0054] Optionally, the thickness of the substrate 10 is 0.5 mm to 30 mm. When the thickness of the substrate 10 is too thin and less than 0.5 mm, the stress is too large and the supporting performance is reduced; when the thickness of the substrate 10 is too thick and higher than 30 mm, the preparation cost is high. Therefore, when the thickness of the substrate 10 is selected within the above range, it can be ensured that the substrate 10 has sufficient support, thermal conductivity, low stress and the preparation cost is controlled within a reasonable range.

[0055] Optionally, the roughness of the first surface (e.g., growth surface 21) of the buffer layer 20 is 1 nm to 1,000,000 nm. When the upper surface roughness of the buffer layer 20 is too small and less than 1 nm, it is not easy to grow its diamond seeds 310 on the surface; when it is too large and greater than 1,000,000 nm, it is impossible to achieve a relatively continuous diamond film 300 growth on the surface, and the structural morphology on the interface is poor. If the upper surface roughness of the buffer layer 20 is selected within the above range, it can ensure that the diamond seeds 310 are easily attached and grown on its surface, and can maintain a stable and reliable morphology. Furthermore, the value range of the upper surface roughness of the buffer layer 20 is controlled between 100 and 50,000 nm, which can be more conducive to achieving the aforementioned performance.

[0056] Optionally, the thickness of the buffer layer 20 is 10nm to 50000nm. When the buffer layer 20 is too thin, it is easy to cause etching of the substrate 10, while when it is too thick, the function of the substrate 10 is weakened and the preparation cost is increased. Therefore, when the thickness of the buffer layer 20 is controlled within the above range, it can ensure effective protection of the substrate 10, enable the substrate 10 to play a better role, and control the preparation cost within a reasonable range. Furthermore, the thickness of the buffer layer 20 is controlled within 500 to 10000nm, which is more conducive to achieving the above-mentioned performance.

[0057] Optionally, the thickness of the heat-conducting layer 50 is 0.05 μm to 100 μm. When the thickness of the heat-conducting layer 50 is too thin, it is easy to make the contact between the layer structures poor and the heat conduction uneven; when the thickness of the heat-conducting layer 50 is too thick, the cost increases and the stress is too high, which is not conducive to improving the temperature uniformity. Therefore, controlling the thickness of the heat-conducting layer 50 within the above range can ensure that the contact between the layer structures is good, the heat transfer is uniform, the thermal stress is small, and the cost is controlled within a reasonable range during the preparation of the base structure 100. Furthermore, controlling the thickness of the heat-conducting layer 50 to 0.1 μm to 50 μm can be more conducive to achieving the aforementioned performance.

[0058] Optionally, the thickness of the thermal conductive substrate 60 is 1 mm to 20 mm. When the thickness of the thermal conductive substrate 60 is too thin, the thermal stress is large and it is easy to bend and deform; and when the thickness of the thermal conductive substrate 60 is too thick, the cost is high. Therefore, if the thickness of the thermal conductive substrate 60 is controlled within the above range, the thermal stress is small, it is not easy to deform, it is not easy to deform and warp, and the cost is controlled within a reasonable range. Furthermore, if the thickness of the thermal conductive substrate 60 is controlled within 2 mm to 15 mm, it can be more conducive to achieving the above performance.

[0059] Optionally, the diamond film 300 is a nanocrystalline diamond film and / or a microcrystalline diamond film. That is, the diamond film 300 can be a single nanocrystalline diamond film, or a single microcrystalline diamond film, or the diamond film 300 can also be a combination of a nanocrystalline diamond film and a microcrystalline diamond film, that is, a structure of nanocrystalline-microcrystalline, microcrystalline-nanocrystal-microcrystalline, nanocrystalline-microcrystalline-nanocrystal, etc.

[0060] The nanocrystalline diamond film has a high specific surface area and high surface activity, which is beneficial for catalytic and sensor applications. The grain size of the nanocrystalline diamond film is very small, and they can provide unique size effects, such as quantum size effect and surface effect, which can be used in electronics and optics. Nanocrystalline diamond film also has semiconductor properties and can be used in electronic devices, such as field effect transistors and optoelectronic devices. Nanocrystalline diamond film can also significantly reduce the friction coefficient and reduce wear, and can be used in precision mechanical parts. Nanocrystalline diamond film can also be chemically modified to make it have good biocompatibility, so that it can be used in the biomedical field.

[0061] The micron-crystalline diamond film inherits the high hardness of diamond and has excellent wear resistance, making it suitable for manufacturing wear-resistant cutting tools and abrasives. The micron-crystalline diamond film has a high thermal conductivity and can effectively conduct heat. It can be used in thermal management systems and as a heat dissipation material. The micron-crystalline diamond film can show good stability in high temperature and chemical corrosion environments, is not easy to react with other substances, can be used in high temperature environments, and can be used in chemical equipment and processes. The micron-crystalline diamond film has high mechanical strength and good impact resistance, and can be used to manufacture high-strength and high-reliability mechanical parts. The micron-crystalline diamond film has good transparency and can be used to manufacture optical windows, lenses and laser components, especially in situations where high purity and high transparency are required. The micron-crystalline diamond film can also exhibit semiconductor properties after doping and can be used in sensors and electronic devices.

[0062] It can be seen that the diamond film 300 with great thickness and excellent performance grown on the upper part of the base structure 100 for growing the diamond film 300 of the present invention can be applied in many fields and has a good market application prospect.

[0063] In some embodiments of the present invention, the material of the heat-conducting layer 50 includes at least one of gold, copper, and a metal alloy having a melting point lower than 1300° C. In these examples, the melting point of gold (Au) is about 1064° C., and the melting point of copper (Cu) is about 1083.4° C., which can be conveniently melted during the preparation of the base structure 100, so that the buffer layer 20 and the heat-conducting substrate 60 can be closely connected. Fig.16As shown, the gold and copper selected for the heat-conducting layer 50 have high thermal conductivity, and heat can be quickly conducted on the heat-conducting layer 50 and quickly transferred to other layer structures connected to the heat-conducting layer 50.

[0064] Optionally, the metal alloy with a melting point lower than 1300°C can be a variety of combinations. Those skilled in the art can make a selection according to the needs and refer to the phase diagram of multi-metals. When making the selection, factors such as economy and availability should also be considered. For example, in some examples, a gold-nickel alloy can be selected, wherein the weight of nickel accounts for less than or equal to 30% of the total alloy weight; a gold-platinum alloy can be selected, wherein the weight of platinum accounts for less than or equal to 10% of the total alloy weight; a gold-tin alloy can be selected, wherein the weight content of tin can be adjusted according to actual needs; a gold-thallium alloy can be selected, wherein the weight content of thallium can be adjusted according to actual needs; a copper-titanium alloy can be selected, wherein the weight content of titanium can be adjusted according to actual needs. Other types of metal alloys are not described here in detail, as long as their melting points are lower than 1300°C, they should be included in the protection scope of the present invention.

[0065] Alternatively, if Fig.16 As shown, the thermally conductive substrate 60 includes at least one of AlN (aluminum nitride), SiC (silicon carbide), Mo (molybdenum), Nb (niobium), Ti (titanium), W (tungsten) or Cr (chromium). The thermal expansion coefficients of these materials are all less than 9×10 -6 / K, and the thermal conductivity is greater than 20W / mK. Therefore, the thermal conductive substrate 60 itself has good thermal conductivity and can resist thermal expansion and thermal shock. The heat in the thermal conductive substrate 60 can be quickly transferred, and the final temperature is relatively uniform. In addition, the melting points of these substances are relatively high, heat-resistant and not easy to melt, which is higher than the melting point of the thermal conductive layer 50. They are stable in nature and have good supporting performance. Most of the above materials selected for the thermal conductive substrate 60 have a melting point higher than 2000°C, can remain stable in a high temperature environment, and can quickly evenly heat.

[0066] Advantageously, the material of the thermally conductive substrate 60 includes graphite and metal, the metal is coated on at least part of the surface of the graphite, and the metal includes at least one of Mo, Nb, Ti, W or Cr. When graphite is added to the thermally conductive substrate 60, the thermal conductivity of the thermally conductive substrate 60 can be improved or the thermal expansion coefficient of the thermally conductive substrate 60 can be reduced, and the cost of the entire thermally conductive substrate 60 can be reduced. For example, the thermally conductive substrate 60 is a composite of graphite and titanium, and titanium metal is coated on the outer surface of the graphite to form the thermally conductive substrate 60. For another example, the thermally conductive substrate 60 is a composite of graphite and chromium, and chromium metal is coated on the outer surface of the graphite to form the thermally conductive substrate 60. Improve the heat dissipation uniformity of the thermally conductive substrate 60, reduce the temperature difference, improve the growth quality of the diamond film 300, and facilitate the subsequent stripping, reducing the cost of the stripping process.

[0067] Advantageously, if Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the orthographic projection of the heat-conducting layer 50 on the surface of the heat-conducting substrate 60 facing the heat-conducting layer 50 is located within the surface of the heat-conducting substrate 60 facing the heat-conducting layer 50. In other words, the heat-conducting substrate 60 covers the entire bottom surface of the heat-conducting layer 50, so that a close connection and full contact between the two can be achieved, ensuring that the heat transferred from the heat-conducting layer 50 can be efficiently transferred to the heat-conducting substrate 60 from all parts of the bottom surface of the heat-conducting layer 50.

[0068] Advantageously, if Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the orthographic projection of the heat-conducting surface 22 of the buffer layer 20 on the surface of the heat-conducting layer 50 facing the buffer layer 20 is located within the surface of the heat-conducting layer 50 facing the buffer layer 20. In other words, the heat-conducting layer 50 covers the entire heat-conducting surface 22, thereby achieving a close connection and full contact between the two, ensuring that the heat transferred from the buffer layer 20 can be efficiently transferred from all parts of the heat-conducting surface 22 to the heat-conducting layer 50.

[0069] In some embodiments of the present invention, Figure 4 , Figure 5 and Figure 6 As shown, a heat-distributing structure 61 is provided on the side of the heat-distributing substrate 60 away from the heat-distributing layer 50 to reduce the temperature difference of each part of the heat-distributing substrate 60, so that the temperature difference of each part is small and the temperature uniformity is improved. The middle part of the heat-distributing substrate 60 is usually close to the heat-distributing layer 50, the buffer layer 20, and the substrate 10. The heat-distributing substrate 60 can quickly absorb the heat from the above-mentioned layers and transfer it inside the heat-distributing substrate 60. At the same time, when the entire base structure 100 is placed on the deposition base 200 for preparation, it will also be in a high-temperature preparation environment. Therefore, the middle and side of the heat-distributing substrate 60 usually have a higher temperature. When the heat-distributing structure 61 is set on the heat-distributing substrate 60, the heat difference caused by the heat source position can be eliminated, so that the overall temperature in the heat-distributing substrate 60 is more uniform, and the uniformity of heat dissipation is improved.

[0070] Advantageously, the heat-saturating structure 61 includes a heat-saturating hole 611 and a heat-saturating groove 612, and the depth of the heat-saturating structure 61 is 0.5 mm to 3 mm. When the depth of the heat-saturating structure 61 is too shallow and less than 0.5 mm, the heat-saturating effect is not obvious, and when the depth of the heat-saturating structure 61 is too large and greater than 3 mm, the processing cost is high. Therefore, limiting the depth of the heat-saturating structure 61 within the above range can ensure sufficient heat-saturating and control the processing cost. For example, the depth of the heat-saturating structure 61 is 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, and 3 mm.

[0071] Advantageously, the depth of the heat-distributing structure 61 accounts for 2.5% to 15% of the thickness of the heat-conducting substrate 60. Within the above depth range, sufficient heat distributing can be ensured and processing cost can be controlled.

[0072] Alternatively, if Figure 6 As shown, the heat-saturating structure 61 includes a heat-saturating hole 611, and the heat-saturating hole 611 is concave from the surface of the heat-conducting substrate 60 away from the heat-conducting layer 50 (for example, the bottom surface of the heat-conducting substrate 60 in the figure) toward the heat-conducting layer 50. In these examples, the heat-saturating hole 611 extends in a small range on the bottom surface of the heat-conducting substrate 60, only in a narrow range, so that a larger number of heat-saturating holes 611 can be set on the bottom surface of the heat-conducting substrate 60 of the same area. For example, in some examples, such as Figure 6 As shown, a plurality of heat balancing holes 611 are arranged in an array on the bottom surface of the heat conductive substrate 60. In the description of the present application, "a plurality" means two or more than two, unless otherwise clearly and specifically defined.

[0073] Alternatively, if Figure 4 and Figure 5 As shown, the heat-scaling structure 61 includes a heat-scaling groove 612 opened on the surface of the heat-conducting substrate 60 away from the heat-conducting layer 50 (for example, the bottom surface of the heat-conducting substrate 60 in the figure), and the heat-scaling groove 612 is concave from the surface of the heat-conducting substrate 60 away from the heat-conducting layer 50 toward the heat-conducting layer 50, and extends on the surface of the heat-conducting substrate 60 away from the heat-conducting layer 50 (for example, the bottom surface of the heat-conducting substrate 60 in the figure). The heat-scaling groove 612 in these examples extends over a large range on the bottom surface of the heat-conducting substrate 60, and at least extends around the geometric center of the heat-conducting substrate 60 for a certain distance, so that by providing a heat-scaling groove 612, a significant heat-scaling effect can be achieved.

[0074] Optionally, the heat distribution structure 61 includes at least one annular groove. The annular groove can greatly reduce the surface area of ​​the heat-conducting substrate 60 away from the heat-conducting layer 50, reduce the heat dissipation efficiency of this part, and improve the heat preservation performance.

[0075] The aforementioned heat-averaging holes 611 and heat-averaging grooves 612 of the present invention can reduce the contact area between the thermally conductive substrate 60 and the deposition base 200, and reduce the heat dissipation efficiency of this part, thereby effectively improving the heat preservation capacity of the thermally conductive substrate 60 in this part, and thus making the heat of the part of the thermally conductive substrate 60 with the heat-averaging structure 61 not further transferred to the deposition base 200, and also making the heat of the part of the thermally conductive substrate 60 with the heat-averaging structure 61 have a higher temperature than the middle and side parts of the thermally conductive substrate 60, so that the heat-averaging performance of the entire thermally conductive substrate 60 is better and the temperature is more uniform.

[0076] Advantageously, if Figure 5 and Figure 6As shown, the total opening area of ​​the heat-distributing structure 61 accounts for 20% to 60% of the bottom area of ​​the heat-distributing substrate 60 , so that the heat-distributing structure 61 can provide effective heat-distributing effect for the heat-distributing substrate 60 , ensuring that the temperature of each part of the heat-distributing substrate 60 is relatively uniform.

[0077] In some specific examples, such as Figure 5 As shown, the heat-scaling structure 61 includes a plurality of annular grooves which are arranged in sequence, and the annular grooves are arranged in sequence around the geometric center of the surface of the heat-conducting substrate away from the heat-conducting layer 50, and the diameter of the innermost heat-scaling groove 612 accounts for 30% to 65% of the maximum distance between two points on the edge of the heat-conducting substrate 60. The annular heat-scaling groove 612 constitutes an annular groove, which is easy to process and occupies a large area, and has a good heat-scaling effect. The position of the heat-scaling groove 612 should not be set too far from the geometric center of the heat-conducting substrate 60, nor should it be set too close to the geometric center of the heat-conducting substrate 60, but should be selected to be set in a specific area where heat preservation is required and heat dissipation efficiency is reduced. By limiting the innermost heat-averaging groove 612 to the above-mentioned ratio range relative to the heat-conducting substrate 60, the setting position of the heat-averaging groove 612 can be appropriately selected, so that the heat-averaging groove 612 will not be too close to the geometric center of the heat-conducting substrate 60, so as not to affect the heat transfer of the heat-conducting substrate 60 close to the geometric center; nor will it be too far from the geometric center of the heat-conducting substrate 60, so as not to affect the heat transfer mode of the side structure of the heat-conducting substrate 60.

[0078] Optionally, the number of the annular heat-averaging grooves 612 is 3 to 6, so that the heat-averaging grooves 612 can achieve a good heat-averaging effect and will not be arranged too densely.

[0079] Of course, the heat balancing groove 612 is not limited to the above-mentioned annular arrangement, and the heat balancing groove 612 can also be in the form of multiple parallel straight segments. Regardless of the structural form of the heat balancing groove 612, the end of the heat balancing groove 612 does not pass through the side of the heat conductive substrate 60, that is, the heat balancing groove 612 is not visible from the side of the heat conductive substrate 60. Similarly, the heat balancing hole 611 is also arranged inside the bottom surface of the heat conductive substrate 60, and the heat balancing hole 611 is not visible from the side of the heat conductive substrate 60.

[0080] In some examples, the heat-dissipating structure 61 is disposed in an annular area at a certain distance from the geometric center of the bottom surface of the thermally conductive substrate 60, and the proximal end of the annular area maintains a certain distance from the geometric center of the thermally conductive substrate 60; and the distal end of the annular area also maintains a certain distance from the geometric center of the thermally conductive substrate 60, and the distal end of the annular area also maintains a certain distance from the edge of the thermally conductive substrate 60.

[0081] In a specific example, the bottom diameter of the thermally conductive substrate 60 is 55 mm to 65 mm, for example, 55 mm, 60 mm or 65 mm; the distance between the proximal end of the annular area and the geometric center of the thermally conductive substrate 60 is 10 mm to 17.5 mm, for example, 10 mm, 14 mm or 17.5 mm; the distance between the distal end of the annular area and the geometric center of the thermally conductive substrate 60 is 20.5 mm to 31.5 mm, for example, 20.5 mm, 24 mm, 28 mm or 31.5 mm; the distance between the distal end of the annular area and the edge of the thermally conductive substrate 60 is 2 mm to 6 mm, for example, 2 mm, 4 mm or 6 mm; the interval between the heat-averaging grooves 612 is 1 to 5 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm or 5 mm; the width of the heat-averaging grooves 612 is 0.5 mm to 3 mm, for example, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm.

[0082] In some embodiments of the present invention, the material of the substrate 10 also includes at least one other material compounded with graphite, the other material being at least one of carbides, nitrides, diamond particles, silicon, titanium, molybdenum, niobium, tantalum and tungsten, wherein the particle size of the diamond particles in the substrate 10 is 5nm to 300000nm, the carbides include at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide and tantalum carbide, and the nitrides include at least one of aluminum nitride, boron nitride, silicon nitride, titanium nitride, tungsten nitride and tantalum nitride. In these examples, the substrate 10 is made of at least two materials, which is a composite layer structure based on graphite. The substrate 10 composed of graphite and other materials can effectively change the wear resistance of graphite itself, so that the substrate 10 has better support and structural strength. It also makes the substrate 10 as a whole have excellent thermal conductivity and low thermal expansion coefficient. For example, in some examples, the composite substrate is a graphite and aluminum nitride substrate, where the aluminum nitride is coated on the surface of the graphite. The composite substrate of the two has a higher thermal conductivity than a single graphite substrate, thereby improving the overall thermal performance. Fig.16 As shown, the thermal expansion coefficient of the material selected for the substrate 10 is less than 9×10 -6 / K, and the thermal conductivity is greater than 20W / mK.

[0083] Advantageously, the mass of graphite in the substrate 10 accounts for 10% to 100% of the total mass of the substrate 10. When the mass proportion of graphite in the substrate 10 is too low, less than 10%, the effect of graphite is reduced and the preparation cost is high. Therefore, the present invention needs to use graphite that is easily available and has good thermal properties as the basic material of the substrate 10.

[0084] In some embodiments of the present invention, the material of the buffer layer 20 includes at least one of carbide, Ti, Mo, W, Ta and Ir; the carbide is at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide and tantalum carbide. In these examples, the melting point of Ti is 1668°C, the melting point of Mo is 2622°C, the melting point of W is 3410°C, the melting point of Ta is 2996°C, and the melting point of Ir is 2443°C. The melting points of these materials are very high, all higher than the melting point of the metal selected for the thermal conductive layer 50; the carbide selected in the buffer layer 20 is also a material with excellent thermal properties. Fig.16 As shown, the thermal expansion coefficient of the material selected for the buffer layer 20 is less than 9×10 -6 / K, and the thermal conductivity is greater than 20W / mK. In the present application, the buffer layer 20 covers the outer surface of the substrate 10, which can achieve a better heat transfer effect between the buffer layer 20 and the substrate 10 and the thermal conductive layer 50, and can also achieve effective protection of the buffer layer 20 on the substrate 10; a diamond film 300 can also be grown on the upper surface of the buffer layer 20.

[0085] In some optional examples, such as Figure 1 As shown, the buffer layer 20 is a single material layer, that is, the buffer layer 20 is made of only one material, and the material can be at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, Ti, Mo, W, Ta and Ir. The buffer layer 20 can be connected to the substrate 10 by chemical vapor deposition, or by bonding.

[0086] In some optional examples, such as Figure 2 As shown, the buffer layer 20 is a multi-layer structure alternately stacked. That is to say, the material of the buffer layer 20 can be at least two of silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, Ti, Mo, W, Ta and Ir, and each material is stacked at least twice. For example, when two materials are selected for alternate stacking, one of which is material A and the other is material B, a layer of material layer A can be first coated on the surface of the substrate 10, and then a layer of material layer B is set on the surface of the material layer A, and another layer of material layer A is made on the surface of the material layer B, and another layer of material layer B is set on the surface of the material layer A, so as to realize material layer A, material layer B, material layer A, material layer B in sequence from the direction away from the substrate 10. When more materials are selected for alternate stacking, the principle is similar and will not be repeated here.

[0087] In some specific examples, the buffer layer 20 selects iridium as the material layer A and selects silicon carbide as the material layer B, and the two materials are alternately stacked, such as Fig.16 As shown, the thermal expansion coefficients of silicon carbide and iridium are both less than 5×10 -6 / K, and the thermal conductivity is greater than 200W / mK, and the structure of silicon carbide is closer to diamond. Then, when the diamond film 300 is grown on the outermost material layer B, i.e., the silicon carbide layer, the interface thermal stress is small, the heat conduction effect is good, the temperature difference at each interface is small, the temperature uniformity is high, and there will be no sudden change in thermal stress on the interface, which provides a reliable basis for growing a diamond film 300 with good performance. This is only a specific example of material selection. The buffer layer 20 of the present invention can be made of any different materials of silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, Ti, Mo, W, Ta and Ir, and there is no limitation here.

[0088] In some optional examples, such as Figure 3 As shown, in the direction from the buffer layer 20 toward the substrate 10, the relative mass contents of the various materials are arranged in a gradient change on different layers. That is to say, multiple gradient layers are formed in the direction away from the substrate 10, taking three gradient layers as an example, namely, the first gradient layer 201, the second gradient layer 202, and the third gradient layer 203. The material of the buffer layer 20 can be at least two of silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, Ti, Mo, W, Ta and Ir. In each gradient layer, the relative mass content of any selected material is different and has a certain gradient change, either increasing or decreasing.

[0089] In some specific examples, the buffer layer 20 uses tungsten carbide and tantalum carbide to make different gradient layers. In the first gradient layer 201, the mass of tungsten carbide accounts for 40%, and the mass of tantalum carbide accounts for 60%; in the second gradient layer 202, the mass of tungsten carbide accounts for 60%, and the mass of tantalum carbide accounts for 40%; in the third gradient layer 203, the mass of tungsten carbide accounts for 80%, and the mass of tantalum carbide accounts for 20%. The tungsten carbide is granular with an average particle size of about 3μm; the tantalum carbide is granular with an average particle size of 5μm. The thermal expansion coefficients of tungsten carbide and tantalum carbide are both less than 6×10 -6 / K, and the thermal conductivity is greater than 20W / mK, especially the thermal properties of tungsten carbide are excellent. In the third gradient layer 203, the content of tungsten carbide is relatively high, so the comprehensive thermal conductivity of the entire gradient layer is higher and the thermal expansion coefficient is smaller, which is closer to the thermal properties of the diamond film 300, which is beneficial to reduce the interface thermal stress between the third gradient layer 203 and the diamond film 300, and improve the thermal conductivity; it also makes the heat conduction between the third gradient layer 203 and the thermal conductive layer 50 faster. In addition, in this example, the mixture of tungsten carbide and tantalum carbide can improve the explosion resistance, making the mechanical properties of the structure better and more stable. This is just a specific example of material selection. The gradient layers of the buffer layer 20 of the present invention can be made of several materials selected from silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, Ti, Mo, W, Ta and Ir, and there is no limitation here.

[0090] In some embodiments of the present invention, Figure 7 As shown, the base structure 100 for growing the diamond film 300 further includes a transition layer 40, which is disposed between the heat conducting surface 22 and the heat conducting layer 50, and the thermal expansion coefficient of the transition layer 40 is smaller than the thermal expansion coefficient of the heat conducting layer 50. By providing the transition layer 40, the bonding force between the heat conducting surface 22 and the heat conducting layer 50 can be increased, the thermal resistance can be reduced, the heat dissipation uniformity can be improved, the temperature difference between the layer structures can be reduced, and finally the preparation quality of the diamond film 300 can be improved.

[0091] Optionally, the material of the transition layer 40 includes at least one of Ti, W, Ir, Ta and Mo. Fig.16 As shown, the thermal expansion coefficients of these materials are less than 6×10 -6 / K, and the thermal conductivity is greater than 20W / mK; the thermal expansion coefficient of these materials is less than the thermal expansion coefficient of gold or copper selected for the heat-conducting layer 50. Then, the thermal properties of the materials selected for the transition layer 40 are between the heat-conducting layer 50 and the buffer layer 20, so that the bonding force between the heat-conducting surface 22 and the heat-conducting layer 50 can be effectively increased, the thermal resistance can be reduced, the heat dissipation uniformity can be improved, and the temperature difference between the layer structures can be reduced, and finally the preparation quality of the diamond film 300 can be improved.

[0092] The following describes a method for preparing the diamond film 300 using the above-mentioned base structure 100.

[0093] The present invention provides a method for preparing a diamond film 300, which is used to prepare the diamond film 300, combined with Figure 8 and Fig. 9 As shown, the preparation method comprises the following steps:

[0094] S10: providing a substrate 10 ; and preparing a buffer layer 20 covering at least a portion of a surface of the substrate 10 .

[0095] Optionally, in step S10, a chemical vapor deposition method or a hot pressing method is used to prepare the substrate 10. The structure and material of the substrate 10 can refer to the description of the substrate 10 in the above examples, and will not be repeated here. In particular, the thickness of the substrate 10 is 0.5 mm to 30 mm, which needs to be controlled during the preparation process.

[0096] Optionally, in step S10, a purchased finished product may be directly provided as the substrate 10. For example, graphite may be directly purchased.

[0097] Optionally, in step S10, a buffer layer 20 is prepared on the substrate 10 by bonding, chemical vapor deposition or hot pressing. The structure and material selection of the buffer layer 20 are described in the above examples, and are not described here. In particular, the thickness of the buffer layer 20 is 10nm to 50000nm, which needs to be controlled during the preparation process.

[0098] S20: providing a heat-conducting substrate 60 and providing a metal layer plate 51 for preparing the heat-conducting layer 50, and placing the metal layer plate 51 between the buffer layer 20 and the heat-conducting substrate 60 to form a preparatory body.

[0099] Optionally, in step S20, when the thermal conductive substrate 60 is a single material layer, it can be directly made from materials available on the market and can be directly purchased and cut into required sizes; when the thermal conductive substrate 60 is a multi-material composite, it can be prepared by bonding or chemical vapor deposition.

[0100] The material of the thermal conductive substrate 60 here includes at least one of AlN, SiC, Mo, Nb, Ti, W or Cr; or the material of the thermal conductive substrate 60 is a composite of graphite and metal, and the graphite in the thermal conductive substrate 60 is composited with at least one of Mo, Nb, Ti, W or Cr, which is consistent with the material selection of the aforementioned thermal conductive substrate 60. The structural parameters of the thermal conductive substrate 60 can refer to the description of the aforementioned thermal conductive substrate 60, which will not be repeated here. The thickness of the thermal conductive substrate 60 should be selected to be 1mm to 20mm.

[0101] Optionally, the metal layer plate 51 can be directly purchased as a finished product available on the market and cut into the required size for use.

[0102] The material of the metal layer plate 51 here includes gold, copper or a metal alloy with a melting point lower than 1300° C. For details, please refer to the above description.

[0103] S30: Place the prepared body into a vacuum chamber and heat it with hydrogen plasma to raise the temperature in the vacuum chamber to 1100°C to 1300°C, wait for the metal layer 51 to melt between the thermally conductive substrate 60 and the buffer layer 20, and then cool down to form a thermally conductive layer 50, which is then taken out as the base structure 100.

[0104] Then, the temperature in the vacuum chamber should be at least not lower than the melting point of the metal layer 51 and not higher than the melting points of other structural layers, so that the metal layer 51 can be smoothly melted between the buffer layer 20 and the thermal conductive substrate 60 in this ambient temperature.

[0105] Optionally, the melting point of the metal layer 51 is consistent with the melting point of the aforementioned thermal conductive layer 50, which should be less than or equal to 1300°C. The melting point of gold (Au) is about 1064°C and the melting point of copper (Cu) is about 1083.4°C. Other selected alloys should also pay attention to the content of each metal and make the melting point of the alloy less than or equal to 1300°C.

[0106] Optionally, the temperature in the vacuum chamber is 1100° C. to 1300° C., such as 1100° C., 1200° C., 1300° C., etc., but must not be lower than the melting point of the metal layer plate 51 .

[0107] S40: cleaning the substrate structure 100 with a detergent; and ultrasonically treating the substrate structure 100 in deionized water for 10 min to 60 min.

[0108] Optionally, in step S40, the lotion is one or more of deionized water, anhydrous ethanol or acetone, and the lotion can be used to clean the substrate 10 with the buffer layer 20, reduce impurities, increase surface purity, and facilitate subsequent processing.

[0109] Optionally, the ultrasonic treatment time in deionized water can be 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, etc. If the time is too long, the efficiency is low, and if the time is too short, the impurity removal effect is not obvious.

[0110] S50: Drying the base structure 100, and performing surface treatment on the base structure 100 using oxygen plasma and / or ozone atmosphere. This step can prepare for growing diamond seeds 310 on the buffer layer 20, so that the surface of the base structure 100 is active, for example, with negative charge.

[0111] S60: preparing a diamond particle suspension, and ultrasonically subjecting the base structure 100 to the diamond particle suspension for 10 to 60 minutes, drying and forming a base structure 100 having a buffer layer 20 of the base structure 100 away from a growth surface 21 of the substrate 10 and with diamond seeds 310 .

[0112] Optionally, in step S60, the diamond particle suspension is prepared by mixing diamond nanocrystal liquid and deionized water at a mass ratio of 1:20 to 50. If the mass ratio is too high (higher than 1:20), the cost is high and the diamond nanocrystal liquid is consumed more; if the mass ratio is too low (e.g., lower than 1:50), it is not conducive to the rapid growth of diamond seeds 310 on the surface of the buffer layer 20 away from the substrate 10, and the preparation time is long. By setting the diamond particle suspension within the above mass ratio range, the consumption of the diamond nanocrystal liquid can be moderate, and the diamond particle suspension can be kept at a certain concentration, and the diamond seeds 310 can be quickly formed on the surface of the buffer layer 20, with low comprehensive preparation cost and high preparation efficiency.

[0113] Optionally, the ultrasonic time in step S60 can be 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, etc. If the time is too long, the efficiency is low, and if the time is too short, the diamond particles will gather less on the surface of the base structure 100 and the effect is not obvious.

[0114] Optionally, when drying the base structure 100 with the diamond seed crystal 310 on the upper surface, it is dried in a nitrogen atmosphere using a heating table at a temperature of 60°C to 90°C. Nitrogen is a protective gas with stable properties, which prevents the diamond seed crystal 310, the buffer layer 20 or the substrate 10 from encountering other reactive gases and participating in the reaction, thereby maintaining the purity of the structure and achieving rapid drying.

[0115] S70 : placing the base structure 100 with the diamond seed crystal 310 in a chemical vapor deposition device, evacuating the device to a vacuum level below 0.001 Pa, introducing a mixed gas of methane, hydrogen and oxygen as a reaction gas, and depositing a diamond film 300 on the growth surface 21 .

[0116] Optionally, the chemical vapor deposition device may be a microwave plasma chemical vapor deposition device, that is, a microwave plasma chemical vapor deposition method (MPCVD) may be used to prepare the diamond film 300 on the surface of the substrate structure 100; or it may be a hot filament chemical vapor deposition device, that is, a hot filament chemical vapor deposition method (Hot filament chemical vapor deposition) may be used to prepare the diamond film 300 on the surface of the substrate structure 100.

[0117] Optionally, in step S70, the reaction gases introduced are hydrogen, oxygen and methane, the flow rate of hydrogen is 300 sccm to 600 sccm, the volume percentage of methane to hydrogen is 0.5% to 5%, and the volume percentage of oxygen to hydrogen is 0.1% to 1%. Within the above gas flow rate and volume percentage range, the required diamond film 300 can be quickly grown on the surface of the base structure 100, with high growth efficiency and good reaction effect.

[0118] Optionally, the total gas pressure of the reaction gas is 9 kPa to 16 kPa, and the working power of the chemical vapor deposition device is 3 kW to 8 kW, and surface deposition is performed. For example, the total gas pressure is 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa or 16 kPa, etc.; for example, the working power of the chemical vapor deposition device is 3 kW, 4 kW, 5 kW, 6 kW, 7 kW or 8 kW, etc.

[0119] In some specific examples, the method for depositing the diamond film 300 is as follows: in a chemical vapor deposition device, the base structure 100 with the diamond seed crystal 310 is first placed on the deposition platform 200. The base structure 100 with the diamond seed crystal 310 and the deposition platform 200 are placed together in the chemical vapor deposition device, and the vacuum is evacuated to 1×10 -4 Pa, hydrogen with a flow rate of 300sccm to 600sccm of hydrogen, 0.5% to 5% by volume of methane, 0.1% to 1% by volume of oxygen mixed gas, the total gas pressure is 9kPa to 16kPa, the working power of the chemical vapor deposition device is 3kW to 8kW, and the diamond film 300 is deposited on the growth surface 21 of the substrate structure 100.

[0120] S80 : removing the base structure 100 to obtain the diamond film 300 .

[0121] Optionally, when removing the base structure 100, one or a combination of hydrochloric acid, sulfuric acid, nitric acid, NaOH, and FeCl3 is used to corrode the heat-conducting layer 50, so that the heat-conducting substrate 60 is separated from the buffer layer 20. Then, in these examples, the heat-conducting layer 50 can be corroded and removed by selecting a suitable corrosive solution. Since the heat-conducting layer 50 is the thinnest among the various layer structures, when the entire base structure 100 is immersed in the corrosive solution, the heat-conducting layer 50 is first corroded and decomposed, so that the heat-conducting substrate 60 on the lower side of the heat-conducting layer 50 is separated from the buffer layer 20, the substrate 10, and the diamond film 300 on the upper side of the heat-conducting layer 50.

[0122] Optionally, the buffer layer 20 and the substrate 10 are further removed by mechanical grinding or acid etching to obtain the diamond film 300 .

[0123] Optionally, the acid solution is one or more of hydrochloric acid solution, nitric acid solution, hydrofluoric acid, and sulfuric acid. By making reasonable selections, some acid solutions can corrode some types of substrates 10 and buffer layers 20, and some acid solutions can quickly corrode the remaining buffer layer 20 and other substances attached to the surface of the diamond film 300 without reacting with the diamond film 300, so that the finished diamond film 300 has high purity and good stripping effect.

[0124] For example, when selecting an acid solution, when the substrate 10 of the present application adopts a silicon layer, dilute hydrofluoric acid can be selected for removal.

[0125] For example, when the substrate 10 or the buffer layer 20 of the present application is a molybdenum metal layer, concentrated nitric acid may be selected for removal.

[0126] For example, when the buffer layer 20 of the present application is an iridium metal layer, it can be removed by using aqua regia or nitric acid solution.

[0127] For example, when the substrate 10 of the present application has a titanium metal layer, a tungsten metal layer, a niobium metal layer or a tantalum metal layer, or when the buffer layer 20 has a titanium metal layer, a tungsten metal layer or a tantalum metal layer, hydrofluoric acid (HF) or a mixture of hydrofluoric acid and other acids (such as nitric acid) can be selected for removal due to their high chemical stability. If necessary, a mixture of hydrofluoric acid and hydrogen peroxide solution can be used to accelerate the removal of the tantalum metal layer.

[0128] For example, when carbide is selected as the material of the substrate 10 or the buffer layer 20 of the present application, a strong acid such as hydrofluoric acid or concentrated sulfuric acid may be used for removal.

[0129] For example, when the material of the substrate 10 of the present application is nitride such as silicon nitride, it is generally highly resistant to acid and can be removed using a mixture of hydrofluoric acid and water.

[0130] Advantageously, the melting point of the substrate 10 in any one or more of the environments of vacuum, argon, hydrogen or nitrogen is higher than 1000°C; the melting point of the buffer layer 20 in any one or more of the environments of vacuum, argon, hydrogen or nitrogen is higher than 1000°C; the melting point of the thermal conductive layer 50 in any one or more of the environments of vacuum, argon, hydrogen or nitrogen is in the range of 850°C to 1300°C; the melting point of the thermal conductive substrate 60 in any one or more of the environments of vacuum, argon, hydrogen or nitrogen is higher than 1000°C, ensuring that each structural layer can remain stable under each preparation environment, and the thermal conductive layer 50 can be formed between the buffer layer 20 and the thermal conductive substrate 60.

[0131] Optionally, the method for preparing the diamond film 300 further includes step S201, using a cutting machine to process a heat-dissipating structure 61 on the bottom of the heat-dissipating substrate 60, and providing a heat-dissipating substrate 60 having the heat-dissipating structure 61. When the cutting machine is used for processing, appropriate processing can be performed according to the size, shape, and pattern of the heat-dissipating structure 61 that has been set.

[0132] Optionally, the method for preparing the diamond film 300 further includes step S202, placing the heat conducting surface 22 of the buffer layer 20 upward and preparing the transition layer 40 by chemical vapor deposition or bonding method, wherein the material of the transition layer 40 includes at least one of Ti, W, Ir, Ta and Mo.

[0133] It can be seen from the above technical scheme that the preparation method of the diamond film 300 proposed by the present invention, when the temperature of the metal layer plate 51 in the vacuum chamber reaches 1100℃~1300℃ during the preparation process, it can be melted beyond the melting point of the metal layer plate 51, so that the metal layer plate 51 is melted into the heat-conducting layer 50 and the heat-conducting substrate 60 and the buffer layer 20 are connected, and the connection performance between the three is good and the temperature transfer is fast. During the whole preparation process, the heat conduction between the buffer layer 20, the substrate 10, the heat-conducting layer 50 and the heat-conducting substrate 60 is uniform and fast, so that during the growth process of the diamond film 300, the temperature difference at each place is small, the temperature uniformity is high, no sudden change occurs, and it is not easy to break due to thermal stress concentration. The prepared diamond film 300 has high quality, large thickness and high yield.

[0134] The substrate structure 100 for growing the diamond film 300 and the method for preparing the diamond film 300 of the present application are further described below with reference to specific embodiments.

[0135] Example 1

[0136] like Figure 1 As shown, the substrate 10 uses sintered graphite as the base, the buffer layer 20 uses silicon carbide, a layer of silicon carbide is wrapped on the surface of the graphite, and a diamond film 300 is grown on the growth surface 21 of the silicon carbide away from the substrate 10 and the heat-conducting layer 50; the heat-conducting layer 50 uses gold, and the heat-conducting substrate 60 uses a molybdenum layer. Among them, the graphite thickness is 2mm, the silicon carbide is 25μm, the growth diameter of the substrate 10 is 2 inches, the thickness of the heat-conducting layer 50 is 2μm, and the thickness of the heat-conducting substrate 60 is 3mm.

[0137] like Figure 8 and Fig. 9 As shown, the specific preparation method of the diamond film 300 in this embodiment is:

[0138] The graphite particles are sintered at high temperature to provide a graphite substrate as the base plate 10 .

[0139] A silicon carbide layer is prepared on the surface of the substrate 10 by chemical vapor deposition as the buffer layer 20 .

[0140] A heat-conducting substrate 60 made of molybdenum is provided, and a metal layer plate 51 made of gold for preparing the heat-conducting layer 50 is provided, and the gold plate is placed between the buffer layer 20 and the heat-conducting substrate 60 to form a preparatory body.

[0141] The prepared body is placed in a vacuum chamber and heated by hydrogen plasma to raise the temperature in the vacuum chamber to between 1100°C and 1300°C. The gold plate is melted between the thermal conductive substrate 60 and the buffer layer 20. After cooling, the metal layer plate 51 forms a gold thermal conductive layer 50, which is taken out as the base structure 100.

[0142] The substrate structure 100 is cleaned with deionized water and anhydrous ethanol; ultrasonically treated in deionized water for 10 minutes, the surface is dried with nitrogen, placed in a surface cleaner and treated with ozone gas for 10 minutes to make the silicon carbide surface active, and then placed in a diamond suspension and ultrasonically treated for 20 minutes to make the growth surface 21 of the silicon carbide buffer layer 20 away from the substrate 10 have diamond seeds 310 (such as Fig. 9 As shown), the diamond suspension is prepared by mixing diamond nanocrystal liquid and deionized water in a mass ratio of 1:20.

[0143] After the ultrasonic treatment, the samples were blown dry with nitrogen and then placed on a heating platform at 80 °C for drying.

[0144] The processed substrate structure 100 with diamond seed crystals 310 is placed on a deposition platform 200 and placed on the deposition platform 200 of a microwave plasma chemical vapor deposition device. After the internal vacuum is evacuated to below 0.001Pa, hydrogen with a flow rate of 450sccm, methane with a flow rate of 12sccm (accounting for 2.67% of the volume percentage of hydrogen) and oxygen with a flow rate of 5sccm (accounting for 1.1% of the volume percentage of hydrogen) are introduced as reaction gases, the gas pressure is 14kPa, the working power of the microwave plasma chemical vapor deposition device is 5.5kW, the temperature of the deposition platform 200 is 910°C, the deposition time is controlled at 250h, and the diamond film 300 is deposited on the silicon carbide surface.

[0145] A mixture of concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO3) in a volume ratio of 3:1, i.e., aqua regia, is used to corrode the gold thermal conductive layer 50, thereby separating the buffer layer 20 from the thermal conductive substrate 60. Then, physical grinding is used to remove silicon carbide and graphite to obtain a diamond film 300, and the final thickness of the diamond film 300 is 0.6 mm.

[0146] like Fig.10 As shown, it can be seen from the SEM test results that the diamond film 300 is continuous and dense, has good uniformity, and has large grains.

[0147] like Fig.11 As shown, in the XRD test results, the 2θ angles are located at 43.7, 75.2, and 91.4, corresponding to the diamond (111), (220), and (311) crystal planes, respectively, and the (111) to (220) peak ratio is 0.51, indicating that the diamond film 300 is mainly composed of the (220) plane, has a good crystal shape, consistent grain orientation, and high quality.

[0148] like Fig.12As shown, it can be obtained from the Raman spectrum data that the Raman peak is located at 1332.05, the FWHM is 8.44, and there is no obvious graphite phase peak, indicating that the quality of the grown diamond is good; the Raman peak is sharp, indicating that the diamond film 300 prepared by the present invention has high crystallinity and good purity.

[0149] In Example 1, silicon carbide can also be replaced by a material that is different from the material of the substrate 10 but has thermal properties close to those of the diamond film 300, such as titanium carbide, tungsten carbide, tantalum carbide, niobium carbide, titanium nitride, Ti, Mo, W, Ta or iridium, preferably iridium, molybdenum, tungsten, and niobium carbide, so as to obtain a structure with similar functions to the above-mentioned base structure 100 of this embodiment. It will not be elaborated here, and technicians in this field should understand that these should all fall within the scope of protection of the present invention.

[0150] It should be noted that the ultrasonic treatment time in deionized water in this embodiment is 10 minutes, and can be longer to 60 minutes to make the cleaning cleaner. The use of 10 minutes can save the time required for ultrasound in this application and improve the preparation efficiency. The surface treatment time with ozone gas is 10 minutes, and can also be longer to 60 minutes to fully activate the surface. The ultrasonic treatment time in the diamond suspension is 20 minutes, and can also be shorter by 10 minutes, or longer than 60 minutes. It can be selected according to actual needs to form the required diamond seeds 310 on the surface of the matrix structure 100. The heating table is dried at 80°C, and other temperature conditions can also be used, with the minimum adjustment to 60°C and the maximum adjustment to 90°C, which are not limited here.

[0151] Example 2

[0152] The preparation method is substantially the same as that of Example 1, except that the microwave plasma chemical vapor deposition device of Example 1 is replaced by a hot wire chemical vapor deposition device. The processed substrate structure 100 with the diamond seed crystal 310 is placed on the deposition base 200 and placed on the deposition base 200 of the hot wire chemical vapor deposition device. After the internal vacuum is evacuated to below 0.001Pa, hydrogen with a hydrogen flow rate of 480sccm, methane with a methane flow rate of 14sccm (accounting for 2.9% of the volume percentage of hydrogen) and oxygen with a flow rate of 5sccm (accounting for 1% of the volume percentage of hydrogen) are introduced as reaction gases, the gas pressure is 9.2kPa, the working power of the microwave plasma chemical vapor deposition device is 7.7kW, the temperature of the deposition base 200 is 900°C, the deposition time is controlled at 350h, and the diamond film 300 is deposited on the growth surface 21 of the silicon carbide buffer layer 20 away from the substrate 10.

[0153] The thickness of the finally produced diamond film 300 is 0.82 mm.

[0154] Test performance, test results can be found in Fig.13 , Fig.14 and Fig.15 .

[0155] like Fig.13 As shown, it can be seen from the SEM test results that the diamond film 300 is continuous, dense and uniform, and the grains are elongated.

[0156] like Fig.14 As shown, in the XRD test results, the 2θ angles are located at 43.8, 75.2, 91.4, and 119.5, corresponding to the diamond (111), (220), (311), and (400) crystal planes, respectively, and the (111) to (220) peak ratio is 0.69, indicating that the diamond film 300 is mainly composed of the (220) plane, has a good crystal shape, consistent grain orientation, and high quality.

[0157] like Fig.15 As shown, the Raman spectrum test shows that the Raman peak is located at 1332.05, the FWHM is 8.44, there is a graphite phase peak, graphite exists, but the diamond phase is obviously more, indicating that the diamond film 300 prepared by the hot wire chemical vapor deposition method on the surface of the buffer layer 20 of the present invention has high crystallinity and good purity.

[0158] Example 3

[0159] The preparation method is generally the same as that of Example 1, except that a composite substrate of graphite and aluminum nitride is used as the substrate 10. Specifically, an aluminum nitride layer is formed on the surface of graphite by thermal sintering, and a buffer layer 20 is formed on the surface of the aluminum nitride layer.

[0160] The chemical vapor deposition time was controlled to be 350 h, and the thickness of the diamond film 300 finally obtained was 0.7 mm.

[0161] In this embodiment, the graphite and aluminum nitride composite can also be graphite and at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide, tantalum carbide, aluminum nitride, boron nitride, silicon nitride, titanium nitride, tungsten nitride, tantalum nitride, diamond particles, silicon, titanium, molybdenum, niobium, tantalum and tungsten, so as to obtain a structure with similar function to the above-mentioned base structure 100 of this embodiment, which will not be elaborated here. Those skilled in the art should understand that these should all fall within the scope of protection of the present invention.

[0162] Example 4

[0163] The preparation method is generally the same as that of Example 1, except that Figure 3As shown, the buffer layer 20 uses tantalum carbide and tungsten carbide and prepares multiple layers to form a gradient layer. Among them, tungsten carbide particles with an average particle size of 3μm and tantalum carbide particles with an average particle size of 5μm are prepared. When preparing the first gradient layer 201, tungsten carbide with a mass ratio of 40% and tantalum carbide with a mass ratio of 60% are used, and they are prepared by hot pressing and sintering; when preparing the second gradient layer 202, tungsten carbide with a mass ratio of 60% and tantalum carbide with a mass ratio of 40% are used, and they are prepared by hot pressing and sintering; in the third gradient layer 203, tungsten carbide with a mass ratio of 80% and tantalum carbide with a mass ratio of 20% are used, and they are prepared by hot pressing and sintering. The relative content of each material is formed in the direction farther away from the geometric center of the substrate 10, and the mass ratio of each material forms a gradient change.

[0164] The chemical vapor deposition time was controlled to be 250 h, and the thickness of the diamond film 300 finally obtained was 0.55 mm.

[0165] The buffer layer 20 in this embodiment can also use any two combinations of silicon carbide, tungsten carbide, niobium carbide, titanium carbide and tantalum carbide, except the combination of tantalum carbide and tungsten carbide, as the required materials, so as to obtain a structure with similar functions to the above-mentioned base structure 100 of this embodiment. It will not be elaborated here, and technicians in this field should understand that these should all fall within the scope of protection of the present invention.

[0166] Example 5

[0167] The preparation method is generally the same as that of Example 1, except that iridium and silicon carbide are alternately stacked in the buffer layer 20. When preparing the buffer layer 20, the iridium is bonded to the surface of the substrate 10 by a bonding method, and then a layer of silicon carbide is prepared on the surface of the iridium by a chemical vapor deposition method, and then repeated multiple times to form a buffer layer 20 with a multi-layer structure. When removing the buffer layer 20 with iridium, a nitric acid solution can be selected for removal.

[0168] The chemical vapor deposition time was controlled to be 320 h, and the thickness of the diamond film 300 finally obtained was 0.65 mm.

[0169] In this embodiment, iridium can also be replaced by one of Ti, Mo, W, and Ta, and silicon carbide can be replaced by one of tungsten carbide, niobium carbide, titanium carbide, and tantalum carbide, so as to obtain a structure with similar functions to the above-mentioned base structure 100 of this embodiment. Details are not given here, and technicians in this field should understand that these should all fall within the scope of protection of the present invention.

[0170] Example 6

[0171] The preparation method is generally the same as that of Example 1, except that a transition layer 40 is provided between the heat conducting layer 50 and the buffer layer 20, and the material of the transition layer 40 is titanium. In the specific preparation process, a layer of titanium needs to be bonded on the heat conducting surface 22 of the buffer layer 20, so as to realize the transition layer 40 with titanium material. Finally, the transition layer 40 can be removed by using concentrated sulfuric acid, hydrofluoric acid and aqua regia.

[0172] The chemical vapor deposition time was controlled to be 270 h, and the thickness of the diamond film 300 finally obtained was 0.62 mm.

[0173] In this embodiment, the transition layer 40 can also be made of other types of materials, for example, Ti can be replaced by W, Ir, Ta and Mo, so as to obtain a structure with similar functions to the above-mentioned base structure 100 of this embodiment. It will not be elaborated here. Those skilled in the art should understand that these should all fall within the scope of protection of the present invention.

[0174] Example 7

[0175] The preparation method is generally the same as that of Example 1, except that before providing the thermally conductive substrate 60, a cutting machine is used to process the bottom surface of the thermally conductive substrate 60 to form a heat-saturating structure 61, and then the thermally conductive substrate 60 having the heat-saturating structure 61, the metal layer plate 51, and the buffer layer 20 are heat-melted. When the cutting machine processes the heat-saturating structure 61, the width of the heat-saturating groove 612 is 2 mm, the depth of the heat-saturating groove 612 is 2 mm, the distance between adjacent heat-saturating grooves 612 is 3 mm, the innermost heat-saturating groove 612 is 14 mm away from the geometric center of the thermally conductive substrate 60, and the outermost heat-saturating groove 612 is 4 mm away from the edge of the thermally conductive substrate 60, and a total of 3 heat-saturating grooves 612 are processed.

[0176] The chemical vapor deposition time was controlled to be 360 ​​h, and the thickness of the diamond film 300 finally obtained was 0.7 mm.

[0177] Example 8

[0178] The preparation method is generally the same as that of Example 1, except that the gold metal layer 51 is replaced with a copper metal layer 51, and a copper heat-conducting layer 50 is formed. During the stripping process, FeCl3 solution is used to etch the copper heat-conducting layer 50, so that the buffer layer 20 is separated from the heat-conducting substrate 60.

[0179] The chemical vapor deposition time was controlled to be 260 h, and the thickness of the diamond film 300 finally obtained was 0.6 mm.

[0180] The above is only a specific embodiment 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 substrate structure for growing a diamond film, characterized in that: include: A substrate, wherein the material of the substrate comprises graphite; A buffer layer, the buffer layer covering at least a portion of the surface of the substrate; the buffer layer having a first surface and a second surface arranged opposite to each other, the first surface comprising a growth surface, the second surface comprising a heat conduction surface, and the growth surface is used to grow a diamond film; A heat-conducting layer, the heat-conducting layer is arranged on the heat-conducting surface; A heat-conducting substrate is disposed on a side of the heat-conducting layer away from the buffer layer, and the melting point of the heat-conducting layer is not higher than the melting point of the heat-conducting substrate and the melting point of the buffer layer.

2. The substrate structure for growing a diamond film according to claim 1, characterized in that: The material of the heat conducting layer includes at least one of gold, copper and a metal alloy having a melting point lower than 1300° C.; and / or, The material of the thermally conductive substrate includes at least one of AlN, SiC, Mo, Nb, Ti, W or Cr; and / or, The material of the thermally conductive substrate includes graphite and metal, the metal is coated on at least a portion of the surface of the graphite, and the metal includes at least one of Mo, Nb, Ti, W or Cr; and / or, The orthographic projection of the heat-conducting layer on the surface of the heat-conducting substrate facing the heat-conducting layer is located within the surface of the heat-conducting substrate facing the heat-conducting layer; the orthographic projection of the heat-conducting surface of the buffer layer on the surface of the heat-conducting layer facing the buffer layer is located within the surface of the heat-conducting layer facing the buffer layer.

3. The substrate structure for growing a diamond film according to claim 1, characterized in that: A heat distribution structure is provided on one side of the heat-conducting substrate away from the heat-conducting layer to reduce the temperature difference at various locations in the heat-conducting substrate.

4. The substrate structure for growing a diamond film according to claim 3, characterized in that: The heat-scaling structure comprises heat-scaling holes and / or heat-scaling grooves, and the depth of the heat-scaling structure is 0.5 mm to 3 mm; and / or, The heat-absorbing hole is concave from the surface of the heat-conducting substrate away from the heat-conducting layer toward the heat-conducting layer; and / or, The heat-absorbing groove is concave from a surface of the heat-conducting substrate away from the heat-conducting layer toward the heat-conducting layer, and is extended from the surface of the heat-conducting substrate away from the heat-conducting layer.

5. The substrate structure for growing a diamond film according to claim 3, characterized in that: The sum of the opening areas of the heat-dissipating structures accounts for 20% to 60% of the bottom area of ​​the heat-conducting substrate; and / or, The depth of the heat-dissipating structure accounts for 2.5% to 15% of the thickness of the heat-conducting substrate; and / or, The heat distribution structure includes at least one annular groove.

6. The substrate structure for growing a diamond film according to claim 5, characterized in that: The heat-balancing structure includes a plurality of annular grooves which are arranged in sequence and are spaced apart from each other around the geometric center of the surface of the heat-conducting substrate away from the heat-conducting layer. The diameter of the innermost heat-balancing groove accounts for 30% to 65% of the maximum distance between two points on the edge of the heat-conducting substrate.

7. The substrate structure for growing a diamond film according to claim 1, characterized in that: The material of the substrate further includes at least one other material compounded with graphite, the other material being at least one of carbide, nitride, diamond particles, silicon, titanium, molybdenum, niobium, tantalum and tungsten, wherein the diamond particles in the substrate have a particle size of 5 nm to 300,000 nm, the carbide includes at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide and tantalum carbide, and the nitride includes at least one of aluminum nitride, boron nitride, silicon nitride, titanium nitride, tungsten nitride and tantalum nitride; and / or, The mass of the graphite in the substrate accounts for 10% to 100% of the total mass of the substrate.

8. The substrate structure for growing a diamond film according to claim 1, characterized in that: The material of the buffer layer includes at least one of carbide, Ti, Mo, W, Ta and Ir; the carbide is at least one of silicon carbide, tungsten carbide, niobium carbide, titanium carbide and tantalum carbide; and / or, The roughness of the first surface of the buffer layer is 1 nm to 1,000,000 nm; and / or, The buffer layer is a multi-layer structure alternately stacked, or in a direction from the buffer layer toward away from the substrate, the mass relative contents of multiple materials are arranged in a gradient variation on different layers.

9. The substrate structure for growing a diamond film according to claim 1, characterized in that: The thickness of the substrate is 0.5 mm to 30 mm; and / or, The thickness of the buffer layer is 10 nm to 50000 nm; and / or, The thickness of the heat-conducting layer is 0.05 μm to 100 μm; and / or, The thickness of the thermally conductive substrate is 1 mm to 20 mm; and / or, The thickness of the diamond film is 0.05 mm to 4 mm.

10. The substrate structure for growing a diamond film according to claim 1, characterized in that: It also includes a transition layer, which is arranged between the heat-conducting surface and the heat-conducting layer, and the thermal expansion coefficient of the transition layer is smaller than the thermal expansion coefficient of the heat-conducting layer.

11. The substrate structure for growing a diamond film according to claim 10, characterized in that: The material of the transition layer includes at least one of Ti, W, Ir, Ta and Mo.

12. A method for preparing a diamond film, characterized in that: For preparing a diamond film, the preparation method comprises the following steps: providing a substrate; preparing a buffer layer covering at least a portion of the surface of the substrate; Providing a heat-conducting substrate and a metal layer plate for preparing a heat-conducting layer, and placing the metal layer plate between the buffer layer and the heat-conducting substrate to form a preparatory body; The preparation is placed in a vacuum chamber, heated by hydrogen plasma, and the temperature in the vacuum chamber is raised to 1100° C. to 1300° C., and the metal layer is melted between the thermally conductive substrate and the buffer layer, and the metal layer is cooled to form a thermally conductive layer, which is then taken out as a base structure; Cleaning the above-mentioned base structure with a lotion; Ultrasonic treatment in deionized water for 10 min to 60 min; Drying the base structure, and subjecting the base structure to surface treatment using oxygen plasma and / or ozone atmosphere; A diamond particle suspension is prepared, and the matrix structure is ultrasonically subjected to 10 to 60 minutes of drying in the diamond particle suspension to form a matrix structure with a buffer layer of the matrix structure away from the growth surface of the substrate with diamond seeds; The substrate structure with the diamond seed is placed in a chemical vapor deposition device, and after the vacuum is evacuated to below 0.001 Pa, a mixed gas of methane, hydrogen and oxygen is introduced as a reaction gas to deposit a diamond film on the growth surface; The base structure is removed to obtain a diamond film.

13. The method for preparing a diamond film according to claim 12, characterized in that: The melting point of the substrate in any one or more of the environments of vacuum environment, argon, hydrogen or nitrogen atmosphere is higher than 1000°C; the melting point of the buffer layer in any one or more of the environments of vacuum environment, argon, hydrogen or nitrogen atmosphere is higher than 1000°C; the melting point of the thermal conductive layer in any one or more of the environments of vacuum environment, argon, hydrogen or nitrogen atmosphere is in the range of 850°C to 1300°C; the melting point of the thermal conductive substrate in any one or more of the environments of vacuum environment, argon, hydrogen or nitrogen atmosphere is higher than 1000°C; and / or, Before placing the metal layer between the buffer layer and the heat-conducting substrate to form a preparatory body, the method further includes: machining a heat-dissipating structure at the bottom of the heat-conducting substrate by a cutting machine tool, and providing a heat-dissipating substrate having a heat-dissipating structure; and / or, Removing the base structure includes: using one or a combination of hydrochloric acid, sulfuric acid, nitric acid, NaOH, and FeCl3 to corrode the thermal conductive layer to separate the thermal conductive substrate from the buffer layer; using mechanical grinding or acid corrosion to further remove the buffer layer and the substrate to obtain the diamond film.

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