Diamond composite material with three-dimensional interpenetrating network and preparation method thereof

Abstract

The invention discloses a diamond composite material with a three-dimensional interpenetrating network, the diamond composite material is of a sandwich structure, the upper surface and the lower surface are CVD polycrystalline diamond layers, and a middle layer substrate is any one of single crystal SiC, single crystal silicon, single crystal aluminum oxide, aluminum oxide ceramic, aluminum nitride ceramic and zirconium oxide ceramic; the diamond composite material is provided with a through-hole array, the hole diameter is 20-100 microns, the ratio of the hole depth to the hole diameter is (5-10): 1, and the hole pitch is 2-10 mm. The diamond composite material with the three-dimensional interpenetrating network structure is prepared, intercommunication of diamonds on the two sides of the middle layer is achieved through homogeneous epitaxial growth, the actual deposition thickness of the diamonds can be reduced by 50% or above, cost is reduced, and meanwhile interface thermal resistance is eliminated through homogeneous epitaxial growth.

Description

Technical Field

[0001] This invention belongs to the field of electronic packaging materials technology, specifically relating to a diamond composite material with a three-dimensional interpenetrating network and its preparation method. Background Technology

[0002] In the field of heat dissipation for modern high-power electronic devices, the performance of heat dissipation materials is crucial. However, traditional heat dissipation materials (such as AlN and SiC ceramics) have a low upper limit of thermal conductivity (≤400 W / m·K), which cannot meet the heat dissipation requirements of high-power devices such as 5G / electric vehicle power modules (>1 kW / cm²). CVD diamond has high thermal conductivity, such as polycrystalline CVD diamond with a thermal conductivity of 1000-1600 W / m·K; however, its deposition rate is low. For example, to prepare a 300μm thick diamond layer, the microwave plasma method requires 50-200 hours, and the DC arc jet method requires 6-10 hours. This results in high costs, limiting its application to high-end fields such as aerospace, and preventing its use in new energy or consumer electronics fields.

[0003] Depositing diamond on silicon-based materials forms silicon carbide at the interface, which effectively reduces interfacial thermal resistance and provides good adhesion. However, directly depositing diamond on non-silicon-based materials (such as Al2O3 and AlN) easily leads to the formation of an amorphous carbon layer at the interface, resulting in an interfacial thermal resistance >50 m²·K / GW and a 30-50% reduction in adhesion strength. At the same time, the amorphous carbon forms conductive channels, reducing volume resistivity, thus significantly diminishing the advantages of CVD-deposited diamond. In addition, traditional filled composite materials suffer from discontinuous heat conduction paths due to uneven diamond dispersion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the low upper limit of thermal conductivity of heat dissipation materials, and a diamond composite material with high thermal conductivity is provided.

[0005] The technical solution of this invention is as follows: A diamond composite material with a three-dimensional interpenetrating network is disclosed. The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom surfaces, and a middle substrate made of any one of single-crystal SiC, single-crystal silicon, single-crystal alumina, alumina ceramic, aluminum nitride ceramic, or zirconium oxide ceramic. The diamond composite material has a through-hole micropore array with a pore size of 20-100 μm, a pore depth to pore size ratio of 5-10:1, and a pore spacing of 2-10 mm. A hexagonal close-packed array is preferred to improve pore density (number of pores per unit area) and thermal conductivity uniformity.

[0006] The thickness of the intermediate substrate is 100-1000μm, the thickness of the CVD polycrystalline diamond layer is 20-200μm, and the polycrystalline diamond layers on both sides are connected by homoepitaxial growth within micropores.

[0007] The aperture is 30-50 μm and the spacing between apertures is 5-8 mm.

[0008] The hole shape is cylindrical or inverted conical with a cone angle of <5° to facilitate gas diffusion during diamond epitaxial growth.

[0009] The method for preparing the diamond composite material with a three-dimensional interpenetrating network is described above. (1) The intermediate layer substrate is pretreated by plasma surface treatment or chemical cleaning to remove the oxide layer, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 20-100 μm. (2) On the undeposited surface of the substrate, the second growth surface opposite to the first growth surface is arrayed with an ultraviolet laser for drilling; (3) The micropores of the array perforation in step (2) are processed by first soaking in oxidizing acid to remove any graphite that may be generated, and then cleaning with hydrofluoric acid to remove the oxide layer. (4) CVD polycrystalline diamond deposition is performed on the second growth surface of the perforated substrate. The homoepitaxial growth rate at the micro-hole location is 10-30 times faster than the heteroepitaxial growth rate on the substrate surface.

[0010] The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using a 30-100nm single-crystal nanodiamond dispersion with a solid content of 1-2%, seed crystals are planted by ultrasonic or spin coating.

[0011] The CVD polycrystalline diamond deposition method on the substrate in steps (1) and (4) is as follows: deposition is carried out by microwave plasma or hot filament CVD, the reaction gas is a CH4 / H2 mixture, the concentration of CH4 is 0.5-2 vol%, the pressure is 3-8 kPa, the temperature is 800-900℃, and the time is 10-12 hours.

[0012] In steps (1) and (4), the thickness of the polycrystalline diamond deposition is 20-100 μm.

[0013] The laser parameters in step (2) are: pulse energy: 50-100μJ, repetition frequency: 50KHz, and scanning speed: 500mm / s.

[0014] The beneficial effects of this invention are: This invention prepares a diamond composite material with a three-dimensional interpenetrating network structure. Homoepitaxial growth enables interconnection of diamond on both sides of the intermediate layer, reducing the actual diamond deposition thickness by more than 50% and thus lowering costs. Simultaneously, homoepitaxial growth eliminates interfacial thermal resistance. This method is compatible with various substrates and can be applied to different scenarios requiring ultra-high thermal conductivity (>900 W / m·K) and excellent insulation (>10 W / m·K).14 Ω·cm), low CTE (<3 ppm / K) and high interfacial bonding strength (>100 MPa).

[0015] This invention utilizes laser drilling to create a micropore array with vertical thermal channels, eliminating lateral thermal resistance in traditional composite materials. Diamond within the micropores grows via homoepitaxial growth, achieving zero interfacial thermal resistance. Restricted gas flow within the pores leads to a localized increase in CH4 concentration (10-20% higher than the specific surface area). The geometrical constraint effect of the pore walls promotes the directional alignment of diamond nuclei (lattice matching >95%). Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the diamond composite material of the present invention. Detailed Implementation

[0017] Example 1 A diamond composite material with a three-dimensional interpenetrating network is disclosed. The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom, and a 6H-SiC 4-inch single crystal substrate in the middle layer with a thickness of 0.3 mm and a surface roughness Ra=100 nm. The diamond composite material has a through-hole micropore array with a pore diameter of 35 μm, a pore depth of 303 μm, and a pore spacing of 6 mm to form a rectangular array. The pore shape is cylindrical or inverted conical with a cone angle of <5°.

[0018] The preparation method of diamond composite material with three-dimensional interpenetrating network is as follows: (1) The intermediate layer substrate is pretreated, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 38 μm. (2) On the undeposited surface of the substrate, the second growth surface opposite the first growth surface is arrayed using an ultraviolet laser (wavelength 355 nm). The laser parameters are: pulse energy: 80 μJ, repetition rate: 50 kHz, scanning speed: 500 mm / s, and focused spot diameter: 15 μm. (3) The micropores of the array punched in step (2) are processed by first soaking in aqua regia for 2 hours and then soaking in hydrofluoric acid for 30 minutes and then cleaning them. (4) CVD polycrystalline diamond deposition was performed on the second growth surface of the perforated substrate for 12 hours, and 48μm polycrystalline diamond was formed on the substrate surface. At the same time, the micropores were vertically interconnected through homoepitaxialization.

[0019] The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using a 30nm single-crystal nanodiamond aqueous dispersion with a solid content of 1.5%, spin-coating seed crystals to ensure a seed crystal density >10. 8 / cm²; The CVD polycrystalline diamond deposition method on the substrate in steps (1) and (4) is as follows: deposition is carried out by microwave plasma, the reaction gas is a CH4 / H2 mixture, the concentration of CH4 / H2 is 1 vol%, the pressure is 3.2 kPa, the temperature is 830℃, and the time is 12 hours.

[0020] Example 2 A diamond composite material with a three-dimensional interpenetrating network is disclosed. The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom, and a 4-inch single-crystal sapphire substrate in the middle layer, 0.5 mm thick, with a surface roughness Ra = 80 nm. The diamond composite material features a through-hole micropore array with a pore diameter of 55 μm, a pore depth of 505 μm, and a center-to-center spacing of 10 mm forming a rectangular array. The pore shape is cylindrical or inverted conical with a cone angle <5°. The preparation method of the diamond composite material with the three-dimensional interpenetrating network includes the following steps: (1) The intermediate layer substrate is pretreated, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 42 μm. (2) On the undeposited surface of the substrate, the second growth surface opposite to the first growth surface is arrayed by an ultraviolet laser (wavelength 355 nm). The laser parameters are: pulse energy: 100 μJ, repetition frequency: 50KHz, scanning speed: 500mm / s, and focused spot diameter: 15μm. (3) The micropores of the array punched in step (2) are processed by first soaking in aqua regia for 2 hours and then soaking in hydrofluoric acid for 30 minutes and then cleaning them. (4) CVD polycrystalline diamond deposition was performed on the second growth surface of the perforated substrate for 12 hours, and 45μm polycrystalline diamond was formed on the substrate surface. At the same time, the micropores were vertically interconnected through homoepitaxialization. The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using a 50nm single-crystal nanodiamond aqueous dispersion with a solid content of 2%, spin-coating seed crystals to ensure a seed crystal density >10. 8 / cm²; The CVD polycrystalline diamond deposition method on the substrate is as follows: deposition is carried out by microwave plasma, the reaction gas is a CH4 / H2 mixture, the CH4 concentration is 1 vol%, the pressure is 4 kPa, the temperature is 850℃, and the time is 10 hours.

[0021] Example 3 A diamond composite material with a three-dimensional interpenetrating network is disclosed. The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom surfaces, and a middle substrate made of 50x50mm aluminum nitride ceramic with a thickness of 0.318mm and a surface roughness Ra=200nm. The diamond composite material has a through-hole micropore array with a pore diameter of 60 μm, a center-to-center spacing of 10 mm forming a rectangular array, and a pore depth of 320μm. The pore shape is cylindrical or inverted conical with a cone angle <5°. The preparation method of the diamond composite material with the three-dimensional interpenetrating network includes the following steps: (1) The intermediate layer substrate is pretreated, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 45 μm. (2) On the undeposited surface of the substrate, the second growth surface opposite to the first growth surface is arrayed using an ultraviolet laser. The laser parameters are: pulse energy: 50-100 μJ, repetition frequency: 50 kHz, and scanning speed: 500 mm / s. (3) The micropores of the array punched in step (2) are processed by first soaking in aqua regia for 2 hours and then soaking in hydrofluoric acid for 30 minutes and then cleaning them. (4) CVD polycrystalline diamond deposition is performed on the second growth surface of the perforated substrate, and 42μm polycrystalline diamond is formed on the substrate surface. At the same time, the micropores are vertically interconnected through homoepitaxialization. The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using an 80nm single-crystal nanodiamond aqueous dispersion with a solid content of 2%, spin-coating seed crystals to ensure a seed crystal density >10. 8 / cm²; The CVD polycrystalline diamond deposition method on the substrate is as follows: deposition is carried out by microwave plasma, the reaction gas is a CH4 / H2 mixture, the concentration of CH4 / H2 is 1 vol%, the pressure is 5 kPa, the temperature is 880℃, and the time is 10 hours.

[0022] Example 4 A diamond composite material with a three-dimensional interpenetrating network is disclosed. The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom surfaces, and a middle substrate of 50x50mm zirconia ceramic with a thickness of 900mm and a surface roughness Ra=200nm. The diamond composite material is equipped with a through-hole micropore array, with pore diameters of 100μm, a center-to-center spacing of 10mm forming a rectangular array, and a pore depth of 905μm. The pore shapes are cylindrical or inverted conical with a cone angle <5°. The preparation method of the diamond composite material with the three-dimensional interpenetrating network includes the following steps: (1) The intermediate layer substrate is pretreated, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 65 μm. (2) On the undeposited surface of the substrate, the second growth surface opposite to the first growth surface is arrayed by an ultraviolet laser (wavelength 355 nm). The laser parameters are: pulse energy: 100 μJ, repetition frequency: 50KHz, scanning speed: 300mm / s, and focused spot diameter: 15μm. (3) The micropores of the array punched in step (2) are processed by first soaking in aqua regia for 2 hours and then soaking in hydrofluoric acid for 30 minutes and then cleaning them. (4) CVD polycrystalline diamond deposition is performed on the second growth surface of the perforated substrate, and 72μm polycrystalline diamond is formed on the substrate surface. At the same time, the micropores are vertically interconnected through homoepitaxialization. The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using a 30nm single-crystal nanodiamond aqueous dispersion with a solid content of 1.5%, spin-coating seed crystals to ensure a seed crystal density >10. 8 / cm²; The CVD deposition method for polycrystalline diamond on the substrate is as follows: deposition is carried out by microwave plasma or hot filament CVD, the reaction gas is a CH4 / H2 mixture, the concentration of CH4 is 1 vol%, the pressure is 5 kPa, the temperature is 880℃, and the time is 15 hours.

[0023] Table 1. Applicable Scenarios and Key Advantages of Intermediate Layer Substrates Table 2 Performance Tests of Examples and Comparative Examples Comparative Example 1 A diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom, and a middle substrate of 4-inch 6H-SiC single crystal with a thickness of 0.3 mm and a surface roughness Ra=100 nm; the preparation steps are as follows: (1) Pre-treat the intermediate layer substrate, and then perform CVD polycrystalline diamond deposition on the first growth surface of the substrate. The deposition thickness of the polycrystalline diamond layer is 20-100 μm. The conditions for CVD polycrystalline diamond are: use 30nm single crystal nanodiamond aqueous dispersion with a solid content of 1.5%, spin-coating seed crystals to ensure that the seed crystal density is >10 8 / cm²; The deposition method was as follows: deposition was carried out by microwave plasma, the reaction gas was a CH4 / H2 mixture, the CH4 concentration was 1 vol%, the pressure was 3.2 kPa, the temperature was 830℃, the time was 12 hours, and the polycrystalline diamond deposition thickness was 36 μm. (2) After spin-coating a seed crystal on the undeposited surface of the substrate and the second growth surface opposite to the first growth surface, CVD polycrystalline diamond deposition is performed. The conditions for CVD polycrystalline diamond are the same as in step (1). Deposition is performed by microwave plasma or hot wire CVD. The reaction gas is a CH4 / H2 mixture, the concentration of CH4 is 1 vol%, the pressure is 4 kPa, the temperature is 850℃, and the time is 12 hours. A 48 μm polycrystalline diamond is formed on the substrate surface.

[0024] Comparative Example 2 A diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom, and a 4-inch single-crystal sapphire substrate in the middle, 0.5 mm thick, with a surface roughness Ra = 80 nm; the preparation steps are as follows: (1) The intermediate layer substrate is pretreated, and then CVD polycrystalline diamond is deposited on the first growth surface of the substrate. The conditions for CVD polycrystalline diamond are as follows: 50nm single crystal nanodiamond aqueous dispersion with a solid content of 2% is used, and seed crystals are spin-coated to ensure that the seed crystal density is >10. 8 / cm²; The deposition method is as follows: deposition is carried out by microwave plasma, the reaction gas is a CH4 / H2 mixture, the CH4 concentration is 1 vol%, the pressure is 4 kPa, the temperature is 850℃, the time is 10 hours, and the polycrystalline diamond deposition thickness is 40 μm. (2) After spin-coating a seed crystal on the undeposited surface of the substrate and the second growth surface opposite to the first growth surface, CVD polycrystalline diamond deposition is performed. The conditions for CVD polycrystalline diamond are the same as in step (1). Deposition is performed by microwave plasma or hot wire CVD. The reaction gas is a CH4 / H2 mixture, the concentration of CH4 is 1 vol%, the pressure is 4 kPa, the temperature is 850℃, and the time is 12 hours. 485 μm polycrystalline diamond is formed on the substrate surface.

[0025] The applicable scenarios and key advantages of the intermediate layer substrate in the above embodiments and comparative examples are shown in Table 1. The performance tests of the embodiments and comparative examples are shown in Table 2.

Claims

1. A diamond composite material with a three-dimensional interpenetrating network, characterized in that: The diamond composite material has a sandwich structure, with CVD polycrystalline diamond layers on the top and bottom, and a middle substrate made of any one of single-crystal SiC, single-crystal silicon, single-crystal alumina, alumina ceramic, aluminum nitride ceramic, and zirconium oxide ceramic. The diamond composite material has a through-hole micropore array with a pore diameter of 20-100 μm, a pore depth to pore diameter ratio of 5-10:1, and a pore spacing of 2-10 mm.

2. The diamond composite material with a three-dimensional interpenetrating network according to claim 1, characterized in that: The aperture is 30-50 μm and the spacing between apertures is 5-8 mm.

3. The diamond composite material with a three-dimensional interpenetrating network according to claim 1, characterized in that: The thickness of the intermediate substrate is 100-1000 μm, and the thickness of the CVD polycrystalline diamond layer is 20-100 μm.

4. The diamond composite material with a three-dimensional interpenetrating network according to claim 1, characterized in that: The hole is cylindrical or an inverted cone with a cone angle of <5°.

5. The method for preparing the diamond composite material with a three-dimensional interpenetrating network according to claims 1-4, characterized in that: (1) Pre-treat the intermediate layer substrate, and then perform CVD polycrystalline diamond deposition on the first growth surface of the substrate; (2) On the undeposited surface of the substrate, the second growth surface opposite to the first growth surface is arrayed with an ultraviolet laser for drilling; (3) The micropores of the array punched in step (2) are treated by soaking in oxidizing acid and then cleaning with hydrofluoric acid; (4) Perform CVD polycrystalline diamond deposition on the second growth surface of the perforated substrate.

6. The method for preparing the diamond composite material with a three-dimensional interpenetrating network according to claim 5, characterized in that: The conditions for depositing CVD polycrystalline diamond on the substrate in steps (1) and (4) are as follows: using a 30-100nm single-crystal nanodiamond dispersion with a solid content of 1-2%, seed crystals are planted by ultrasonic or spin coating.

7. The method for preparing the diamond composite material with a three-dimensional interpenetrating network according to claim 5, characterized in that: The CVD polycrystalline diamond deposition method on the substrate in steps (1) and (4) is as follows: deposition is carried out by microwave plasma or hot filament CVD, the reaction gas is a CH4 / H2 mixture, the concentration of CH4 is 0.5-2 vol%, the pressure is 3-8 kPa, the temperature is 800-900℃, and the time is 10-12 hours.

8. The method for preparing the diamond composite material with a three-dimensional interpenetrating network according to claim 5, characterized in that: In steps (1) and (4), the thickness of the polycrystalline diamond deposition is 20-100 μm.

9. The method for preparing the diamond composite material with a three-dimensional interpenetrating network according to claim 5, characterized in that: The laser parameters in step (2) are: pulse energy: 50-100 μJ, repetition frequency: 50KHz, and scanning speed: 500 mm / s.

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