A method for preparing large-size HFCVD diamond film material

Abstract

The invention discloses a large-size HFCVD diamond film material preparation method, comprising the following steps: producing a diamond film material by a hot wire production device, wherein the diameter of the diamond film is greater than or equal to 100 mm; the hot wire production device is provided with a deposition space, wherein the deposition space comprises a hot wire assembly, a deposition base, and a reflection ring; then starting the hot wire heating to make the upper surface of the deposition base reach a preset temperature; adjusting the height of the reflection ring, and arranging the reflection ring at the periphery of the cooling platform; when the thickness of the diamond film deposited on the surface of the deposition base reaches a preset requirement, stopping the introduction of methane, and still introducing hydrogen; continuing to maintain the hot wire heating for a certain period of time; then adjusting the height of the reflection ring, and arranging the reflection ring outside the deposition base for staged cooling; achieving small internal stress of the diamond film material, no cracking phenomenon occurs during the cooling process of the diamond film production, and no cracking, edge collapse, poor parallelism, and other problems occur in the diamond film during the grinding and polishing process.

Description

Technical Field

[0001] The invention relates to the field of diamond preparation, and in particular to the field of a method for preparing a large-size HFCVD diamond film material. Background Art

[0002] Diamond has excellent mechanical properties, high temperature resistance, optical transmittance and thermal properties, and is used in various precision machining tools, high temperature special devices, optical windows and thermal management chips. Among the preparation methods of diamond, CVD is the best method for preparing high-quality, large-size diamond single crystals and thick / thin films. CVD methods include microwave plasma CVD (MPCVD), hot filament CVD (HFCVD), DC arc plasma jet CVD (DCAP CVD), etc.

[0003] The large-scale preparation of CVD diamond is the only way to reduce application costs and meet application needs. When preparing large-size diamond films, there will be huge stress inside the diamond film, which will cause the diamond to crack and break during the cooling process, greatly reducing the available size. Even if no cracking occurs during the cooling process, in the processing of optical windows and thermal management chips, due to the long-term grinding and polishing, the existence of stress may also cause processing failure, resulting in cracking, edge collapse, poor parallelism and other problems.

[0004] Therefore, how to prepare large-sized diamond film materials, achieve low internal stress in the diamond film materials, prevent cracking during the cooling process of diamond film production, and prevent cracking, edge collapse, and poor parallelism of the diamond film during grinding and polishing has become a difficult problem that needs to be solved urgently in this field. Summary of the invention

[0005] In order to solve the above technical problems, a large-size HFCVD diamond film material preparation method is provided to prepare large-size diamond film materials, so that the internal stress of the diamond film material is small, and there is no cracking phenomenon during the cooling process of diamond film production. The diamond film will not crack, collapse, or have poor parallelism during the grinding and polishing process.

[0006] According to the present invention, a method for preparing a large-size HFCVD diamond film material is provided, comprising the following steps:

[0007] Producing diamond film material by hot wire production device, wherein the diameter of the diamond film is ≥100 mm;

[0008] The hot wire production device is provided with a deposition space, wherein the deposition space includes a hot wire assembly, a deposition base, and a reflection ring;

[0009] The hot wire assembly comprises a plurality of hot wires arranged in parallel;

[0010] The reflection ring is sleeved outside the deposition base;

[0011] The deposition base comprises a deposition substrate and a cooling platform, wherein the deposition substrate is placed on the upper surface of the cooling platform;

[0012] evacuating the deposition space;

[0013] Introduce hydrogen and methane in proportion to the target pressure;

[0014] Then, the hot wire is turned on to heat the upper surface of the deposition substrate to a preset temperature; the height of the reflection ring is adjusted and the reflection ring is set at the periphery of the cooling stage;

[0015] When the thickness of the diamond film deposited on the surface of the deposition substrate reaches the preset requirement, the introduction of methane is stopped, but hydrogen is still introduced; the hot wire heating is continued for a certain period of time;

[0016] Then adjust the height of the reflection ring, set the reflection ring outside the deposition substrate, and perform segmented cooling;

[0017] After the temperature is lowered, the hydrogen in the furnace is discharged and the furnace is inflated to atmospheric pressure;

[0018] Then the diamond film is removed from the surface of the substrate material to obtain a diamond film material.

[0019] Compared with the prior art, the invention has the following beneficial effects: the hot wire method production device is used to produce diamond film materials, which is conducive to the production of large-sized diamond films; by adjusting the height of the reflection ring, the reflection ring is set at the periphery of the cooling stage, so that during the diamond deposition process, the cooling stage is located inside the reflection ring, and the reflection ring is used to help avoid the problem of temperature reduction around the deposition substrate caused by the cooling stage, and avoid the low temperature of the cooling stage from affecting the temperature of the upper surface of the deposition substrate, so that the temperature of the central part of the upper surface of the deposition substrate is basically consistent with the temperature of the edge of the deposition substrate, so that the structure of each part of the deposited diamond film is uniform, and no defects will appear on the edge;

[0020] When the thickness of the diamond film deposited on the surface of the deposition substrate reaches the preset requirement, the introduction of methane is stopped, hydrogen is still introduced, and the hot wire heating is continued for a certain period of time, so that the deposition process of the diamond film is stopped, the number of carbon-containing groups in the deposition chamber is rapidly reduced, and the concentration of active atomic hydrogen is rapidly increased. The active atomic hydrogen etches the non-diamond phase in the deposited diamond film, so that the non-diamond phase content inside the membrane is reduced in this process; the stress generated by the thermal expansion difference between the diamond and non-diamond phases during the cooling and subsequent processes is reduced, thereby reducing the probability of cracking; at the same time, atoms have the ability to migrate at high temperatures, and the density of various defects is reduced through atomic migration, and an annealing relaxation process occurs, thereby reducing the stress generated by various defects, thereby reducing the cracking ratio;

[0021] By adjusting the height of the reflection ring, the reflection ring is set at the periphery of the deposition substrate, and the temperature is lowered in sections, so that the diamond film is located inside the reflection ring during the cooling process. The existence of the reflection ring allows more heat to be reflected to the edge of the deposition area, avoiding the problem of different cooling speeds at the edge and center of the deposition substrate during cooling, thereby avoiding the problem of cracking of the diamond film at the edge of the deposition substrate due to high stress and the problem of cracks extending inward, and avoiding the problems of cracking, edge collapse, poor parallelism, etc. of the diamond film during grinding and polishing.

[0022] By performing segmented cooling, the temperature is kept constant for a certain period of time after a certain degree of cooling, so that the contraction difference between the diamond film and the deposition substrate caused by the difference in thermal expansion can be released to a certain extent, reducing the huge tensile stress caused by the difference in thermal expansion, thereby reducing the probability of collapse and cracking of the diamond self-supporting film; at the same time, after three times of contraction difference release, the diamond film can be separated from the deposition substrate more completely, greatly improving the integrity of the diamond thick film;

[0023] This will ultimately result in low internal stress in the diamond film material, no cracking during the cooling process of the diamond film production, and no cracking, edge collapse, poor parallelism, or other problems during the grinding and polishing process of the diamond film.

[0024] Furthermore, the distance between the plane where the filament is located and the plane where the upper surface of the deposition substrate is located is 2-10 mm;

[0025] The hydrogen and methane are introduced to a target pressure of 4000-8000 Pa; the volume ratio of methane to hydrogen is (3-15):(85-97).

[0026] The beneficial effect of the above step is that the distance between the plane where the filament is located and the plane where the upper surface of the deposition substrate is located is 2-10 mm, which is conducive to achieving a preset high temperature on the upper surface of the deposition substrate and achieving uniform temperature at various parts of the surface of the deposition substrate;

[0027] By introducing hydrogen and methane to a target pressure of 4000-8000Pa; the volume ratio of methane to hydrogen is (3-15): (85-97), which is conducive to achieving uniform distribution and full contact between hydrogen and methane, and is conducive to obtaining a diamond film with fewer defects and less graphite phase.

[0028] Furthermore, the preset temperature of the upper surface of the deposition substrate is 800-1000°C.

[0029] The beneficial effect of adopting the previous step is that it is conducive to achieving fewer defects and less graphite phase in the obtained diamond film, and at the same time it is conducive to avoiding the problem of deformation of the deposition substrate or the cooling platform surface during the deposition process and the cooling process due to excessive temperature.

[0030] Furthermore, the reflection ring is a ring structure; the height of the ring structure is greater than 1.5 times the sum of the thickness of the deposited substrate and the maximum thickness of the deposited diamond film;

[0031] The reflective ring is connected with a telescopic device.

[0032] The beneficial effect of adopting the above step is that, by making the height of the annular structure greater than 1.5 times the sum of the thickness of the deposition substrate and the maximum thickness of the deposited diamond film, it is further beneficial to control the temperature of the edge of the deposition substrate to be substantially consistent with the temperature at the center of the deposition substrate;

[0033] The reflection ring is connected with a telescopic device, so that the deposition ring can be set at different positions at different times, which is further beneficial to the uniform temperature of various parts on the upper surface of the deposition substrate during the diamond film deposition process and the uniform temperature of various parts of the diamond film during the cooling process.

[0034] Furthermore, the cooling medium in the cooling station is water, and the outlet water temperature of the cooling medium is 45-60°C;

[0035] and / or

[0036] The interface temperature between the deposition substrate and the cooling device is 100-250°C.

[0037] The beneficial effect of the above step is that the cooling medium in the cooling stage is water, and the outlet water temperature of the cooling medium is 45-60°C, that is, the deposition substrate is cooled uniformly, which is conducive to avoiding the problem of uneven temperature of various parts of the deposition substrate caused by excessive cooling; thereby, it is conducive to avoiding the problem of cracking of the diamond film;

[0038] The interface temperature between the deposition substrate and the cooling device is 100-250°C, which helps to avoid the problem of deformation of the deposition substrate due to long-term high temperature caused by too slow cooling.

[0039] Furthermore, the introduction of methane is stopped, and while hydrogen is still introduced, the heating power of the hot wire is continued to be maintained for 1-10 hours.

[0040] Furthermore, the segmented cooling comprises the following steps:

[0041] In the first cooling process, the temperature of the upper surface of the deposition substrate is reduced from the preset temperature to 88%-92% of the preset temperature, and then the temperature is maintained for 0.5-2h;

[0042] In the second cooling process, the temperature of the upper surface of the deposition substrate is reduced to 78%-82% of the preset temperature and maintained at the temperature for 0.5-2h;

[0043] The third cooling process is to reduce the temperature of the upper surface of the deposition substrate to 68%-72% of the preset temperature and maintain the temperature for 1-4 hours;

[0044] The fourth cooling process reduces the surface temperature of the deposition substrate to room temperature.

[0045] The beneficial effect of adopting the above step is that through the first cooling process, the second cooling process and the third cooling process, a small amount of cooling is achieved in stages, which avoids the problem of deformation of the diamond film due to rapid cooling, and is also conducive to avoiding the problem of uneven cooling of various parts of the diamond film due to excessive cooling, and is conducive to avoiding the problem of cracking of the diamond film due to excessive cooling; in addition, by keeping the temperature constant for a certain period of time during each cooling stage, the contraction difference caused by the difference in thermal expansion between the diamond film and the deposition substrate is released to a certain extent, and the problem of deformation, collapse and cracking of the diamond film due to the huge tensile stress caused by the thermal expansion difference is reduced; at the same time, during the cooling process, it is conducive to etching and eliminating the graphite phase in the diamond film by hydrogen;

[0046] At the same time, through three times of differential contraction release, the diamond film can be completely separated from the deposition substrate, which improves the integrity of the diamond thick film;

[0047] The internal stress of the large-size diamond film material prepared is small, and the diamond film will not crack during the cooling process of production. The diamond film will not crack, collapse, or have poor parallelism during the grinding and polishing process. It is simple to operate, highly controllable, has a short production cycle, and reduces production costs.

[0048] Furthermore, in the first cooling process, the flow rate of hydrogen introduced is reduced to 88%-92% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 10-12% of the preset hydrogen flow rate;

[0049] In the second cooling process, the flow rate of hydrogen is reduced to 78%-82% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 18%-22% of the preset hydrogen flow rate;

[0050] In the third cooling process, the flow rate of hydrogen is reduced to 68%-72% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 28%-32% of the preset hydrogen flow rate;

[0051] In the fourth cooling process, the introduction of hydrogen is stopped, and the flow rate of nitrogen or inert gas introduced is 80-100% of the preset hydrogen flow rate.

[0052] The benefit of adopting the previous step is that, during the segmented cooling process, the hydrogen introduced is reduced segmentally and inert gas is introduced gradually, which not only avoids the danger of hydrogen discharge, but also helps to have a certain concentration of hydrogen in the higher temperature section during the cooling process, which is beneficial to etching the graphite phase in the deposited diamond film and improving the strength of the diamond film.

[0053] Furthermore, the deposition substrate material is one of silicon, silicon nitride, molybdenum and graphite.

[0054] The beneficial effect of adopting the previous step is that it helps to reduce the thermal expansion difference between the diamond film and the deposition substrate, thereby helping to reduce the tensile stress generated by the thermal expansion difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the structure of the deposition base, the reflection ring, and the hot wire during the deposition process of Example 1;

[0056] Figure 2 This is a schematic diagram of the structure of the deposition base, the reflection ring, and the hot wire during the segmented cooling process of Example 1.

[0057] As shown in the figure:

[0058] 1. Hot wire, 2. Diamond film, 3. Deposition substrate, 4. Reflection ring, 5. Cooling stage. DETAILED DESCRIPTION

[0059] In order to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0060] Embodiment 1:

[0061] This embodiment provides a method for preparing a large-sized HFCVD diamond film material, comprising the following steps:

[0062] The diamond film 2 material is produced by a hot wire production device, wherein the diameter of the diamond film is 180 mm;

[0063] The hot wire production device is provided with a deposition space, wherein the deposition space includes a hot wire 1 assembly, a deposition base, and a reflection ring 4;

[0064] The hot wire 1 assembly includes a plurality of hot wires 1 arranged in parallel; the distance between the plane where the filaments are located and the plane where the upper surface of the deposition substrate 3 is located is 6 mm;

[0065] The reflection ring 4 is sleeved on the outside of the deposition base;

[0066] The deposition base comprises a deposition substrate 3 and a cooling platform 5. The deposition substrate 3 is placed on the upper surface of the cooling platform 5. The deposition substrate 3 is made of molybdenum.

[0067] The reflection ring 4 is a ring structure; the height of the ring structure is 1.8 times the sum of the thickness of the deposition substrate 3 and the maximum thickness of the deposited diamond film 2; the reflection ring 4 is connected to a telescopic device;

[0068] The cooling medium in the cooling stage 5 is water, and the outlet water temperature of the cooling medium is 53°C; the interface temperature between the deposition substrate 3 and the cooling device is 175°C.

[0069] evacuating the deposition space;

[0070] Introducing hydrogen and methane in proportion to a target pressure; the hydrogen and methane are introduced to a target pressure of 6000 Pa; the volume ratio of methane to hydrogen is 9:91;

[0071] Then, the hot wire 1 is turned on for heating, and the upper surface of the deposition substrate 3 reaches a preset temperature; the preset temperature of the upper surface of the deposition substrate 3 is 800-1000° C.; the height of the reflection ring 4 is adjusted, and the reflection ring 4 is set at the periphery of the cooling stage 5;

[0072] When the thickness of the diamond film 2 deposited on the surface of the deposition substrate 3 reaches the preset requirement, the introduction of methane is stopped, and hydrogen is still introduced; the heating of the hot wire 1 is continued for 5.5 hours;

[0073] Then adjust the height of the reflection ring 4, and place the reflection ring 4 on the periphery of the deposition substrate 3 to perform segmented cooling;

[0074] The segmented cooling comprises the following steps:

[0075] In the first cooling process, the temperature of the upper surface of the deposition substrate 3 is reduced from a preset temperature to 90% of the preset temperature, and then the temperature is maintained for 1.3 hours;

[0076] In the second cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 80% of the preset temperature and maintained at the temperature for 1.3 hours;

[0077] In the third cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 70% of the preset temperature and maintained at the temperature for 2.5 hours;

[0078] The fourth cooling process is to reduce the temperature of the upper surface of the deposition substrate 3 to room temperature;

[0079] In the first cooling process, the flow rate of hydrogen is reduced to 90% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 11% of the preset hydrogen flow rate;

[0080] In the second cooling process, the flow rate of hydrogen is reduced to 80% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 20% of the preset hydrogen flow rate;

[0081] In the third cooling process, the flow rate of hydrogen is reduced to 70% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 30% of the preset hydrogen flow rate;

[0082] In the fourth cooling process, the hydrogen is stopped and the flow rate of nitrogen or inert gas is 90% of the preset hydrogen flow rate;

[0083] After the temperature is lowered, the hydrogen in the furnace is discharged and the furnace is inflated to atmospheric pressure;

[0084] Then the diamond film 2 is removed from the surface of the base material to obtain the diamond film 2 material.

[0085] Embodiment 2:

[0086] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0087] This embodiment provides a method for preparing a large-size HFCVD diamond film material, comprising the following steps:

[0088] The diameter of the diamond film is 200 mm; the distance between the plane where the filament is located and the plane where the upper surface of the deposition substrate 3 is located is 3 mm;

[0089] The deposition substrate 3 is made of silicon;

[0090] The cooling medium in the cooling stage 5 is water, and the outlet water temperature of the cooling medium is 58°C; the interface temperature between the deposition substrate 3 and the cooling device is 245°C.

[0091] Introducing hydrogen and methane in proportion to a target pressure; the introducing hydrogen and methane to a target pressure of 7500 Pa; the volume ratio of methane to hydrogen is 5:95;

[0092] The preset temperature of the upper surface of the deposition substrate 3 is 950°C;

[0093] When the thickness of the diamond film 2 deposited on the surface of the deposition substrate 3 reaches the preset requirement, the introduction of methane is stopped, and hydrogen is still introduced; the heating of the hot wire 1 is continued for 3 hours;

[0094] In the first cooling process, the temperature of the upper surface of the deposition substrate 3 is reduced from a preset temperature to 91% of the preset temperature, and then maintained at that temperature for 1 hour;

[0095] In the second cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 81% of the preset temperature and maintained at the temperature for 0.8 h;

[0096] In the third cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 71% of the preset temperature and maintained at the temperature for 1.5 hours;

[0097] The fourth cooling process is to reduce the temperature of the upper surface of the deposition substrate 3 to room temperature;

[0098] In the first cooling process, the flow rate of hydrogen is reduced to 91% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 11.5% of the preset hydrogen flow rate;

[0099] In the second cooling process, the flow rate of hydrogen is reduced to 81% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 21% of the preset hydrogen flow rate;

[0100] In the third cooling process, the flow rate of hydrogen is reduced to 71% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 31% of the preset hydrogen flow rate;

[0101] In the fourth cooling process, the introduction of hydrogen is stopped, and the flow rate of nitrogen or inert gas introduced is 98% of the preset hydrogen flow rate.

[0102] Embodiment 3:

[0103] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0104] This embodiment provides a method for preparing a large-size HFCVD diamond film material, comprising the following steps:

[0105] The diameter of the diamond film is 160 mm; the distance between the plane where the filament is located and the plane where the upper surface of the deposition substrate 3 is located is 8 mm;

[0106] The deposition substrate 3 is made of graphite;

[0107] The cooling medium in the cooling stage 5 is water, and the outlet water temperature of the cooling medium is 46°C; the interface temperature between the deposition substrate 3 and the cooling device is 120°C.

[0108] Introducing hydrogen and methane in proportion to a target pressure; the introducing hydrogen and methane to a target pressure of 5000 Pa; the volume ratio of methane to hydrogen is 12:88;

[0109] The preset temperature of the upper surface of the deposition substrate 3 is 850°C;

[0110] When the thickness of the diamond film 2 deposited on the surface of the deposition substrate 3 reaches the preset requirement, the introduction of methane is stopped, and hydrogen is still introduced; the heating of the hot wire 1 is continued for 8 hours;

[0111] In the first cooling process, the upper surface temperature of the deposition substrate 3 is reduced from a preset temperature to 89% of the preset temperature, and then the temperature is maintained for 1.8 hours;

[0112] In the second cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 79% of the preset temperature and maintained at the temperature for 1.8 hours;

[0113] In the third cooling process, the upper surface temperature of the deposition substrate 3 is reduced to 689% of the preset temperature and maintained at the temperature for 3.8 hours;

[0114] The fourth cooling process is to reduce the temperature of the upper surface of the deposition substrate 3 to room temperature;

[0115] In the first cooling process, the flow rate of hydrogen is reduced to 89% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 10.5% of the preset hydrogen flow rate;

[0116] In the second cooling process, the flow rate of hydrogen is reduced to 81% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 19% of the preset hydrogen flow rate;

[0117] In the third cooling process, the flow rate of hydrogen is reduced to 69% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 29% of the preset hydrogen flow rate;

[0118] In the fourth cooling process, the introduction of hydrogen is stopped, and the flow rate of nitrogen or inert gas introduced is 85% of the preset hydrogen flow rate.

[0119] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A method for preparing a large-sized HFCVD diamond film material, characterized in that: The following steps are involved: Producing diamond film material by hot wire production device, wherein the diameter of the diamond film is ≥100 mm; The hot wire production device is provided with a deposition space, wherein the deposition space includes a hot wire assembly, a deposition base, and a reflection ring; The hot wire assembly comprises a plurality of hot wires arranged in parallel; The reflection ring is sleeved outside the deposition base; The deposition base comprises a deposition substrate and a cooling platform, wherein the deposition substrate is placed on the upper surface of the cooling platform; evacuating the deposition space; Introduce hydrogen and methane in proportion to the target pressure; Then, the hot wire is turned on to heat the upper surface of the deposition substrate to a preset temperature; the height of the reflection ring is adjusted and the reflection ring is set at the periphery of the cooling stage; When the thickness of the diamond film deposited on the surface of the deposition substrate reaches the preset requirement, the introduction of methane is stopped, but hydrogen is still introduced; the hot wire heating is continued for a certain period of time; Then adjust the height of the reflection ring, set the reflection ring outside the deposition substrate, and perform segmented cooling; After the temperature is lowered, the hydrogen in the furnace is discharged and the furnace is inflated to atmospheric pressure; Then the diamond film is removed from the surface of the substrate material to obtain a diamond film material.

2. The method for preparing a large-size HFCVD diamond film material according to claim 1, characterized in that: The distance between the plane where the filament is located and the plane where the upper surface of the deposition substrate is located is 2-10 mm; The hydrogen and methane are introduced to a target pressure of 4000-8000 Pa; the volume ratio of methane to hydrogen is (3-15):(85-97).

3. The method for preparing a large-size HFCVD diamond film material according to claim 1, characterized in that: The preset temperature of the upper surface of the deposition substrate is 800-1000°C.

4. The HFCVD diamond film continuous preparation method according to claim 1, characterized in that: The reflection ring is a ring structure; the height of the ring structure is greater than 1.5 times the sum of the thickness of the deposited substrate and the maximum thickness of the deposited diamond film; The reflective ring is connected with a telescopic device.

5. The method for preparing a large-sized HFCVD diamond film material according to claim 1, characterized in that: When a diamond film is deposited on the surface of a deposition substrate, the height of the reflection ring is adjusted by a telescopic device, and the reflection ring is arranged on the periphery of the cooling stage.

6. The method for preparing a large-sized HFCVD diamond film composite material according to claim 1, characterized in that: The cooling medium in the cooling station is water, and the outlet water temperature of the cooling medium is 45-60°C; and / or The interface temperature between the deposition substrate and the cooling device is 100-250°C.

7. The method for preparing a large-sized HFCVD diamond film material according to claim 1, characterized in that: Stop the introduction of methane, while still introducing hydrogen, continue to maintain the heating power of the hot wire, and heat for 1-10 hours.

8. The method for preparing a large-sized HFCVD diamond film material according to claim 1, characterized in that: The segmented cooling comprises the following steps: In the first cooling process, the temperature of the upper surface of the deposition substrate is reduced from the preset temperature to 88%-92% of the preset temperature, and then the temperature is maintained for 0.5-2h; In the second cooling process, the temperature of the upper surface of the deposition substrate is reduced to 78%-82% of the preset temperature and maintained at the temperature for 0.5-2h; The third cooling process is to reduce the temperature of the upper surface of the deposition substrate to 68%-72% of the preset temperature and maintain the temperature for 1-4 hours; The fourth cooling process reduces the surface temperature of the deposition substrate to room temperature.

9. The method for preparing a large-sized HFCVD diamond film material according to claim 8, characterized in that: In the first cooling process, the flow rate of hydrogen is reduced to 88%-92% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 10-12% of the preset hydrogen flow rate; In the second cooling process, the flow rate of hydrogen is reduced to 78%-82% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 18%-22% of the preset hydrogen flow rate; In the third cooling process, the flow rate of hydrogen is reduced to 68%-72% of the preset hydrogen flow rate, and nitrogen or inert gas is introduced at the same time, and the flow rate of nitrogen or inert gas is 28%-32% of the preset hydrogen flow rate; In the fourth cooling process, the introduction of hydrogen is stopped, and the flow rate of nitrogen or inert gas introduced is 80-100% of the preset hydrogen flow rate.

10. The method for preparing a large-sized HFCVD diamond film material according to claim 1, characterized in that: The deposition substrate material is one of silicon, silicon nitride, molybdenum and graphite.

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