Method for preparing diamond wafer from silicon carbide waferTechnical Field
The invention relates to the field of semiconductor material preparation, in particular to a method for preparing a diamond wafer by using a silicon carbide wafer.
Background
Diamond is known for its high thermal conductivity, which can be up to 2200-2600W/(m, K), a value 4-5 times greater than copper and silver, 4 times greater than silicon carbide (SiC), 13 times greater than silicon (Si), and 43 times greater than gallium arsenide (GaAs). The high heat conductivity makes diamond an ideal heat dissipation material, and can rapidly conduct heat generated in the working process of the semiconductor chip, so that the problems of performance degradation, reliability degradation and the like of the chip due to overhigh temperature are effectively avoided.
The diamond also has the characteristics of wide forbidden band, high breakdown field strength, high carrier saturation drift speed and the like, and the characteristics lead the diamond to have wide and irreplaceable application advantages and prospects under the high-frequency and high-pressure conditions. The band gap of diamond is 5.5eV, carrier mobility is 3 times of that of silicon material, and the diamond has extremely low intrinsic carrier concentration at room temperature and excellent high temperature resistance. These characteristics make diamond a powerful competitor for the next generation of semiconductor materials.
In summary, the reasons for using the diamond wafer as the semiconductor material mainly include the characteristics of high thermal conductivity, thermal expansion coefficient matched with the semiconductor material, wide forbidden band, high carrier mobility, excellent high temperature resistance and the like, and these characteristics together give the diamond a wide application prospect in the semiconductor field. A
However, a major bottleneck currently restricting the development of diamond semiconductor performance is that single crystal diamond wafers are difficult to manufacture in large volumes at low cost.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for preparing a diamond wafer by using a silicon carbide wafer.
In order to achieve the above purpose, the invention is implemented according to the following technical scheme:
The invention aims to provide a method for preparing a diamond wafer from a silicon carbide wafer, which comprises the following steps of:
S1, assembling a high-temperature ultrahigh-pressure heteroepitaxial diamond wafer synthesis block, wherein the synthesis block comprises a pyrophyllite square pipe with a cylindrical cavity inside, a composite pyrophyllite pipe is embedded in the inner wall of the cylindrical cavity of the pyrophyllite square pipe, the inner diameter of the composite pyrophyllite pipe is the same as that of the pyrophyllite square pipe, a heating pipe is sleeved in the composite pyrophyllite pipe, heating plates are arranged at the two ends of the heating pipe, insulating cups are sleeved in the heating pipe, sealing insulating plates are arranged at the two ends of the insulating cups, a composite pyrophyllite Dan Feng sealing block and a pyrophyllite sealing block are sequentially arranged at the two end openings of the composite pyrophyllite pipe from inside to outside, a conductive steel ring is arranged at the center of the composite pyrophyllite sealing block and the pyrophyllite sealing block, the inner end surface of the conductive steel ring is in contact with the outer end surface of the heating plate, a plurality of high-temperature ultrahigh-pressure heteroepitaxial diamond wafer synthesis blocks are sleeved in the insulating cups, sealing carbon plates are respectively arranged at the top end and the tail ends of the carbon pipes, and a plurality of insulating plates are respectively arranged in the insulating plates from top to bottom, and a plurality of insulating layers are sequentially arranged between the two carbon plates and the top end surfaces of the carbon plates are sequentially contacted with the top surfaces of the carbon plates and the top surfaces of the carbon plates;
s2, preparing a high-temperature ultrahigh-pressure heteroepitaxial diamond wafer, namely loading the synthetic block into a synthetic cavity of a hexahedral press, adopting a sectional boosting process, raising the pressure in the synthetic cavity to 4.5-6 GPa, enabling the temperature to reach 1400-1700 ℃ and keeping for 100-180 minutes, melting nickel-manganese-cobalt alloy sheets on two sides of a silicon carbide wafer between every two layers of isolation carbon sheets, enabling silicon in the silicon carbide wafer to be fused into the nickel-manganese-cobalt alloy sheets, and finally generating the diamond wafer by rearranging residual carbon atoms in the silicon carbide wafer in a diamond crystal structure because the high-temperature ultrahigh-pressure environment in the synthetic cavity is in a diamond stable region, and cooling the diamond wafer to room temperature.
Further, the weight percentage of nickel in the first nickel-manganese-cobalt alloy sheet and the second nickel-manganese-cobalt alloy sheet is 50% -80%, the weight percentage of manganese is 15% -30%, and the weight percentage of cobalt is 1% -10%.
Further, the thickness of the silicon carbide wafer is 0.2-2 mm.
Further, the thickness of the first nickel-manganese-cobalt alloy sheet and the second nickel-manganese-cobalt alloy sheet is 0.1-2mm.
Compared with the prior art, the method adopts a high-temperature ultrahigh-pressure heteroepitaxy mode, takes the silicon carbide wafer as the raw material, realizes batch manufacturing of high-performance low-cost diamond wafers on a large-scale domestic cubic press, has high growth speed compared with the existing single crystal diamond process, has wide market prospect, solves the problem of low-cost manufacturing of the base raw material for developing a fourth-generation semiconductor, and can realize 1-4 inches and synthesize 10-40 diamond wafers at a time.
Drawings
Fig. 1 is a schematic diagram of the structure of an assembled high temperature ultra high pressure heteroepitaxial diamond wafer synthesis block of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. The specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.
A method for preparing a diamond wafer from a silicon carbide wafer, comprising the steps of:
S1, assembling a high-temperature ultrahigh-pressure heteroepitaxial diamond wafer synthesis block, wherein the synthesis block comprises a pyrophyllite square tube 1 with a cylindrical cavity inside, a composite pyrophyllite tube 2 is embedded into 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 that of the pyrophyllite square tube as shown in FIG. 1; a heating pipe 3 is arranged in the composite pyrophyllite pipe 2, heating plates 4 are arranged at two ends of the heating pipe 3, an insulating cup 5 (dolomite cup) is arranged in the heating pipe 3, and plugging insulating plates 6 are arranged at two ends of the insulating cup 5; the composite pyrophyllite tube 2 is sequentially provided with a composite pyrophyllite Dan Feng block and a pyrophyllite block 11 from inside to outside at two ports, a conductive steel ring 12 is arranged at the center of the composite pyrophyllite block and the pyrophyllite block 11, the inner end surface of the conductive steel ring 12 is contacted with the outer end surface of a heating 4 sheet, a high-temperature ultrahigh-pressure heteroepitaxial diamond wafer synthesis block is sleeved in an insulating cup 5, the high-temperature ultrahigh-pressure heteroepitaxial diamond wafer synthesis block comprises a carbon tube 7 sleeved on the inner wall of the insulating cup 5, blocking carbon sheets 8 are respectively arranged at the top end and the tail end of the carbon tube 7, a plurality of isolation carbon sheets 9 are arranged in the carbon tube 7 from top to bottom, a nickel manganese cobalt alloy sheet I10, a silicon carbide wafer 14 and a nickel manganese cobalt alloy sheet II 13 are sequentially paved between two adjacent isolation carbon sheets 9 from bottom to top, wherein the nickel manganese cobalt alloy sheet I10 and the nickel manganese cobalt alloy sheet II 13 have the weight percentage of 50% -80%, the weight percentage of manganese is 15% -30%, the weight percentage of cobalt is 1% -10%, the nickel cobalt alloy sheet I and the nickel alloy II is 0.2 mm, the thickness of the silicon carbide wafer 13 is 0.2-2 mm, the lower end face of the isolation carbon sheet at the lowest layer in the carbon tube 7 is contacted with the upper end face of the blocking carbon sheet 8 at the lower end of the carbon tube 7, and the upper end face of the isolation carbon sheet at the uppermost layer in the carbon tube is contacted with the lower end face of the blocking carbon sheet 8 at the upper end of the carbon tube 7;
S2, preparing a high-temperature ultrahigh-pressure heteroepitaxial diamond wafer, namely loading the synthetic block into a synthetic cavity of a hexahedral press, adopting a sectional boosting process, raising the pressure in the synthetic cavity to 4.5-6 GPa, enabling the temperature to reach 1400-1700 ℃ and keeping for 20-180 minutes, melting nickel-manganese-cobalt alloy sheets on two sides of a silicon carbide wafer 14 between every two layers of isolation carbon sheets 9, enabling silicon in the silicon carbide wafer 14 to be fused into the nickel-manganese-cobalt alloy sheets, and finally enabling residual carbon atoms in the silicon carbide wafer 14 to be rearranged in a diamond crystal structure because the high-temperature ultrahigh-pressure environment in the synthetic cavity is in a diamond stable region, finally generating a diamond wafer with the thickness of 0.2-2 mm, taking out the diamond wafer from a carbon tube, and cooling to room temperature.
The diamond wafer in this embodiment is grown, and thus can be mass-produced.
The technical scheme of the invention is not limited to the specific embodiment, and all technical modifications made according to the technical scheme of the invention fall within the protection scope of the invention.