Method of manufacturing silicon carbide single crystal ingot
The present invention provides a method including: a temperature raising step of raising a temperature in a crystal growing furnace with a silicon carbide raw material and a silicon carbide seed crystal arranged therein to a crystal growing temperature; a single crystal growing step of maintaining the crystal growing temperature and causing a silicon carbide single crystal to grow on the silicon carbide seed crystal; and a temperature lowering step of lowering the temperature in the crystal growing furnace from the crystal growing temperature to stop growth of the silicon carbide single crystal, in which the method further comprises, between the single crystal growing step and the temperature lowering step, a temperature lowering preparation step of maintaining the temperature in the crystal growing furnace at the crystal growing temperature and causing concentration of nitrogen gas in the crystal growing furnace to increase to be higher than concentration of nitrogen gas in the temperature raising step and in the single crystal growing step, and in which the concentration of the nitrogens gas in the crystal growing furnace in the temperature lowering step is higher than the concentration of the nitrogen gas in the temperature raising step and the single crystal growing step.
1. A method of manufacturing a silicon carbide single crystal ingot in which a silicon carbide single crystal is made to grow on a silicon carbide seed crystal in a mixture gas containing nitrogen at a temperature of 2000° C. or higher in a crystal growing furnace, the method comprising:
a temperature raising step of raising a temperature in the crystal growing furnace with a silicon carbide raw material and the silicon carbide seed crystal arranged therein to a crystal growing temperature;
a single crystal growing step of maintaining the crystal growing temperature and causing the silicon carbide single crystal to grow on the silicon carbide seed crystal; and
a temperature lowering step of lowering the temperature in the crystal growing furnace from the crystal growing temperature to stop growth of the silicon carbide single crystal,
wherein the method further comprises, between the single crystal growing step and the temperature lowering step, a temperature lowering preparation step of maintaining the temperature in the crystal growing furnace at the crystal growing temperature and causing a volume ratio of nitrogen gas in the mixture gas in the crystal growing furnace to increase so as to be higher than the volume ratio of nitrogen gas in the mixture gas in the temperature raising step and in the single crystal growing step, and
wherein the volume ratio of the nitrogen gas in the mixture gas in the crystal growing furnace in the temperature lowering step is higher than the volume ratio of the nitrogen gas in the mixture gas in the temperature raising step and the single crystal growing step.
2. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein the temperature lowering preparation step is performed within a range of equal to or greater than 5 hours and equal to or less than 15 hours.
3. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein the volume ratio of the nitrogen gas in the mixture gas in the crystal growing furnace in the temperature lowering step is set to be equal to or greater than 30 vol %.
4. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein in the temperature lowering step, a temperature lowering speed is increased by an endothermic reaction of the nitrogen gas in the crystal growing furnace.
5. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein the method of manufacturing a silicon carbide single crystal ingot is a sublimation method.
6. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein the volume ratio of the nitrogen gas in the mixture gas in the temperature raising step is the same as the volume ratio of the nitrogen gas in the mixture gas in the single crystal growing step.
7. The method of manufacturing a silicon carbide single crystal ingot according to claim 1 ,
wherein a highest volume ratio of the nitrogen gas in the mixture gas in the temperature lowering preparation step is the same as the volume ratio of the nitrogen gas in the mixture gas in the temperature lowering step.