A method for preparing heteroepitaxial diamond silicon carbide composite wafer

Abstract

The present invention belongs to the technical field of diamond heat dissipation materials and specifically discloses a method for preparing heteroepitaxial diamond-silicon carbide composite wafers. The synthesis block is loaded into a six-sided press and processed using a staged pressurization process. The nickel-manganese-cobalt alloy sheet within each layer melts, and the silicon carbide wafer contacts the alloy sheet on one side. The silicon within the silicon carbide wafer then integrates into the nickel-manganese-cobalt alloy sheet. Because the high-temperature, ultrahigh-pressure environment within the synthesis chamber is in the diamond's stable zone, the remaining carbon atoms within the silicon carbide wafer rearrange themselves in a diamond crystal structure, resulting in a heteroepitaxial diamond-silicon carbide composite wafer. By doping the diamond surface with boron and the silicon carbide surface with phosphorus, the present invention integrates the PN junction structure, a fundamental component of chip manufacturing, onto the wafer. This allows the production of semiconductor chips with higher voltage resistance, faster operating speed, greater temperature resistance, and smaller process steps. This method has important strategic significance for the microelectronics industry and the development of high-performance chips. Furthermore, 10 to 40 heteroepitaxial diamond-silicon carbide composite wafers can be synthesized in a single batch.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor material preparation, in particular to a method for preparing a heteroepitaxial diamond silicon carbide composite wafer. Background Art

[0002] Silicon carbide (SiC) has a unique crystal structure, employing a hexagonal close-packed structure similar to diamond. This structure gives SiC excellent thermal conductivity and high high-temperature resistance. Compared to traditional silicon materials, SiC has a wider bandgap, providing a higher electron band spacing, thereby achieving higher electron mobility and lower leakage current. In addition, SiC has a high electron saturation drift velocity and low intrinsic resistivity, providing better performance for high-power applications. These characteristics make SiC wafers have broad application prospects in multiple fields. SiC wafers can be used to manufacture high-power density switching devices, such as power modules for electric vehicles and solar inverters. Their high thermal conductivity and high high-temperature resistance enable stable operation in high-temperature environments, enabling more efficient energy conversion and more compact designs.

[0003] Diamond also possesses properties such as a wide bandgap, high breakdown field strength, and high carrier saturation drift velocity. These characteristics give it a wide range of irreplaceable advantages and prospects for applications under high-frequency and high-voltage conditions. Diamond has a bandgap of 5.5 eV, a carrier mobility three times that of silicon, and an extremely low intrinsic carrier concentration at room temperature, resulting in excellent high-temperature resistance. These properties make diamond a more suitable semiconductor material than silicon carbide.

[0004] If silicon carbide and diamond can be combined as a semiconductor material, it will undoubtedly be a better way. However, the main bottleneck restricting the development of diamond semiconductor performance is not only the difficulty in mass-producing single-crystal diamond wafers at low cost, but also the high concentration of N-type doping of diamond, which will remain a bottleneck difficult to break through in the short term. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a heteroepitaxial diamond-silicon carbide composite wafer.

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0007] The object of the present invention is to provide a method for preparing a heteroepitaxial diamond silicon carbide composite wafer, comprising the following steps:

[0008] S1. Assemble the diamond silicon carbide composite wafer synthesis block: the synthesis block includes a pyrophyllite square tube with a cylindrical cavity inside, the inner wall of the cylindrical cavity of the pyrophyllite square tube is embedded with a composite pyrophyllite tube, and the inner diameter of the composite pyrophyllite tube is the same as the inner diameter of the pyrophyllite square tube; a heating tube is sleeved in the composite pyrophyllite tube, heating plates are provided at both ends of the heating tube, an insulating cup is sleeved in the heating tube, and sealing insulating plates are provided at both ends of the insulating cup; composite pyrophyllite sealing blocks and pyrophyllite sealing blocks are provided at the two ends of the composite pyrophyllite tube from the inside to the outside, and a conductive steel ring is provided through the center of the composite pyrophyllite sealing block and the pyrophyllite sealing block, and the conductive steel ring the inner end face of the insulating cup contacts the outer end face of the heating plate; a diamond silicon carbide composite wafer synthesis block is sleeved in the insulating cup, and the diamond silicon carbide composite wafer synthesis block includes a carbon tube sleeved on the inner wall of the insulating cup, and a sealing carbon sheet is respectively provided in the top and end of the carbon tube. A plurality of isolation carbon sheets are provided in the carbon tube from top to bottom, and a nickel-manganese-cobalt alloy sheet and a silicon carbide wafer sheet are sequentially laid between two adjacent isolation carbon sheets from bottom to top; the lower end face of the isolation carbon sheet in the lowest layer of the carbon tube contacts the upper end face of the sealing carbon sheet at the lower end of the carbon tube, and the upper end face of the isolation carbon sheet in the highest layer of the carbon tube contacts the lower end face of the sealing carbon sheet at the upper end of the carbon tube;

[0009] S2. Preparation of diamond silicon carbide composite wafers: The above-mentioned synthesis block is loaded into the synthesis chamber of the six-sided top press, and the staged pressure-increasing process is used to increase the pressure in the synthesis chamber to 4.5~6GPa, and the temperature reaches 1400~1700 degrees and is maintained for 20~80 minutes. Each layer of nickel-manganese-cobalt alloy sheet melts, and the silicon carbide wafer contacts one side of the nickel-manganese-cobalt alloy sheet. The silicon in the silicon carbide wafer will be integrated into the nickel-manganese-cobalt alloy sheet. Because the high temperature and ultra-high pressure environment in the synthesis chamber is in the stable zone of diamond, the remaining carbon atoms in the silicon carbide wafer are rearranged in the diamond crystal structure, and finally heteroepitaxially grown into a diamond layer silicon carbide composite wafer. The diamond layer silicon carbide composite wafer is taken out of the carbon tube and cooled to room temperature.

[0010] Furthermore, in the nickel-manganese-cobalt alloy sheet, the weight percentage of nickel is 50% to 80%; the weight percentage of manganese is 15% to 30%; and the weight percentage of cobalt is 1% to 10%.

[0011] Furthermore, the thickness of the silicon carbide wafer is 0.2-2 mm.

[0012] Furthermore, the thickness of the nickel-manganese-cobalt alloy sheet is 0.1-2 mm.

[0013] Compared with the existing technology, the present invention can integrate the most basic PN junction structure for chip manufacturing on the wafer by doping boron on the diamond surface and phosphorus on the silicon carbide surface, thereby manufacturing semiconductor chips with higher voltage resistance, faster operating speed, higher temperature resistance and smaller process. It has important strategic significance for the microelectronics industry and high-performance chip development; and 10 to 40 diamond-silicon carbide composite wafers can be synthesized at a time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of the diamond silicon carbide composite wafer synthesis block assembled in the present invention. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] A method for preparing a heteroepitaxial diamond-silicon carbide composite wafer comprises the following steps:

[0017] S1. Assemble diamond silicon carbide composite wafer synthesis block: Figure 1 As shown, the synthesis block includes a pyrophyllite square tube 1 with a cylindrical cavity inside, and a composite pyrophyllite tube 2 is embedded in the inner wall of the cylindrical cavity of the pyrophyllite square tube 1, and the inner diameter of the composite pyrophyllite tube 2 is the same as the inner diameter of the pyrophyllite square tube; a heating tube 3 is sleeved in the composite pyrophyllite tube 2, and heating plates 4 are provided at both ends of the heating tube 3, and an insulating cup 5 (dolomite cup) is sleeved in the heating tube 3, and sealing insulating plates 6 are provided at both ends of the insulating cup 5; composite pyrophyllite sealing blocks and pyrophyllite sealing blocks 11 are provided at the two ends of the composite pyrophyllite tube 2 in sequence from the inside to the outside, and a conductive steel ring 12 is provided through the center of the composite pyrophyllite sealing block and the pyrophyllite sealing block 11, and the inner end face of the conductive steel ring 12 is in contact with the outer end face of the heating plates 4; a diamond silicon carbide composite wafer synthesis block is sleeved in the insulating cup 5, and the diamond silicon carbide composite wafer synthesis block is The block includes a carbon tube 7 sleeved on the inner wall of an insulating cup 5, with a plugging carbon sheet 8 provided at the top and end of the carbon tube 7, respectively. A plurality of isolation carbon sheets 9 are provided in the carbon tube 7 from top to bottom, and a nickel-manganese-cobalt alloy sheet 10 and a silicon carbide wafer 13 are laid in sequence from bottom to top between two adjacent isolation carbon sheets 9, wherein the weight percentage of nickel in the nickel-manganese-cobalt alloy sheet 10 is 50% to 80%; the weight percentage of manganese is 15% to 30%; and the weight percentage of cobalt is 1% to 10%; the thickness of the nickel-manganese-cobalt alloy sheet 10 is 0.1-2 mm, and the thickness of the silicon carbide wafer 13 is 0.2-2 mm; the lower end face of the isolation carbon sheet in the lowest layer in the carbon tube 7 contacts the upper end face of the plugging carbon sheet 8 at the lower end of the carbon tube 7, and the upper end face of the isolation carbon sheet in the highest layer in the carbon tube contacts the lower end face of the plugging carbon sheet 8 at the upper end of the carbon tube 7;

[0018] S2. Preparation of diamond silicon carbide composite wafer: The above-mentioned synthesis block is loaded into the synthesis chamber of the six-sided top press, and the staged pressure-increasing process is adopted to increase the pressure in the synthesis chamber to 4.5~6GPa, and the temperature reaches 1400~1700 degrees and is maintained for 20~80 minutes. Each layer of nickel-manganese-cobalt alloy sheet 10 melts, and the silicon carbide wafer 13 contacts one side of the nickel-manganese-cobalt alloy sheet 10. The silicon in the silicon carbide wafer 13 will be integrated into the nickel-manganese-cobalt alloy sheet 10. Because the high temperature and ultra-high pressure environment in the synthesis chamber is in the stable zone of diamond, the remaining carbon atoms in the silicon carbide wafer 13 are rearranged in the diamond crystal structure, and finally a heteroepitaxial diamond layer silicon carbide composite wafer with a thickness of 0.2~2mm is generated, that is, one side is diamond and the other side is silicon carbide; the diamond layer silicon carbide composite wafer is taken out from the carbon tube 7 and cooled to room temperature.

[0019] During the actual preparation process, different synthesis pressures and times can be adjusted in the cavity, which will form lattice defects of different concentrations in the diamond layer in the composite wafer, reserving vacancies for subsequent diamond layer doping. The final product is made into a semiconductor power device by doping the diamond layer with boron and the silicon carbide layer with phosphorus.

[0020] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a heteroepitaxial diamond-silicon carbide composite wafer, characterized in that: The following steps are involved: S1. Assemble the diamond silicon carbide composite wafer synthesis block: the synthesis block includes a pyrophyllite square tube with a cylindrical cavity inside, the inner wall of the cylindrical cavity of the pyrophyllite square tube is embedded with a composite pyrophyllite tube, and the inner diameter of the composite pyrophyllite tube is the same as the inner diameter of the pyrophyllite square tube; a heating tube is sleeved in the composite pyrophyllite tube, heating plates are provided at both ends of the heating tube, an insulating cup is sleeved in the heating tube, and sealing insulating plates are provided at both ends of the insulating cup; composite pyrophyllite sealing blocks and pyrophyllite sealing blocks are provided at the two ends of the composite pyrophyllite tube from the inside to the outside, and a conductive steel ring is provided through the center of the composite pyrophyllite sealing block and the pyrophyllite sealing block, and the conductive steel ring the inner end face of the insulating cup contacts the outer end face of the heating plate; a diamond silicon carbide composite wafer synthesis block is sleeved in the insulating cup, and the diamond silicon carbide composite wafer synthesis block includes a carbon tube sleeved on the inner wall of the insulating cup, and a sealing carbon sheet is respectively provided in the top and end of the carbon tube. A plurality of isolation carbon sheets are provided in the carbon tube from top to bottom, and a nickel-manganese-cobalt alloy sheet and a silicon carbide wafer sheet are sequentially laid between two adjacent isolation carbon sheets from bottom to top; the lower end face of the isolation carbon sheet in the lowest layer of the carbon tube contacts the upper end face of the sealing carbon sheet at the lower end of the carbon tube, and the upper end face of the isolation carbon sheet in the highest layer of the carbon tube contacts the lower end face of the sealing carbon sheet at the upper end of the carbon tube; S2. Preparation of diamond silicon carbide composite wafers: The above-mentioned synthesis block is loaded into the synthesis chamber of the six-sided top press, and the staged pressure-increasing process is used to increase the pressure in the synthesis chamber to 4.5-6GPa, and the temperature reaches 1400-1700 degrees and is maintained for 20-80 minutes. Each layer of nickel-manganese-cobalt alloy sheet melts, and the silicon carbide wafer contacts one side of the nickel-manganese-cobalt alloy sheet. The silicon in the silicon carbide wafer will be integrated into the nickel-manganese-cobalt alloy sheet. Because the high-temperature and ultra-high-pressure environment in the synthesis chamber is in the stable zone of diamond, the remaining carbon atoms in the silicon carbide wafer are rearranged in the diamond crystal structure, and finally a heteroepitaxial diamond layer silicon carbide composite wafer is generated. The diamond layer silicon carbide composite wafer is taken out from the carbon tube and cooled to room temperature.

2. The method for preparing a heteroepitaxial diamond-silicon carbide composite wafer according to claim 1, wherein: In the nickel-manganese-cobalt alloy sheet, the weight percentage of nickel is 50% to 80%; the weight percentage of manganese is 15% to 30%; the weight percentage of cobalt is 1% to 10%, and the sum of the weight percentages of nickel, manganese and cobalt is 100%.

3. The method for preparing a heteroepitaxial diamond-silicon carbide composite wafer according to claim 1, wherein: The thickness of the silicon carbide wafer is 0.2-2 mm.

4. The method for preparing a heteroepitaxial diamond-silicon carbide composite wafer according to claim 1, wherein: The thickness of the nickel-manganese-cobalt alloy sheet is 0.1-2 mm.

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