Method for producing silicon carbide single crystal
A silicon carbide single crystal is grown by a method comprising: a single crystal growth step of growing a silicon carbide single crystal so as to not close a gap between a side surface of the silicon carbide single crystal growing on a silicon carbide seed crystal, and an inner-side surface of a guide member and a crystal deposited on the inner-side surface of the guide member; a crystal growth termination step of terminating crystal growth by temperature lowering; and a gap enlargement step, performed between the single crystal growth step and the crystal growth termination step, of enlarging the gap by maintaining a difference, Pin−Pout, between partial pressure Pin of Si 2 C in a source gas in the vicinity of an inlet of the gap and partial pressure Pout of Si 2 C in a source gas in the vicinity of an outlet of the gap at 0.18 torr or less.
1. A method for producing a silicon carbide single crystal in which a single crystal of silicon carbide is grown on a silicon carbide seed crystal placed inside a crucible by using a guide member to guide a source gas to the silicon carbide seed crystal side, wherein the guide member has one end positioned in the vicinity of the silicon carbide seed crystal, and the method comprising:
a single crystal growth step of growing a silicon carbide single crystal in a manner so as to not completely close a gap between a side surface of the silicon carbide single crystal growing on the silicon carbide seed crystal, and an inner-side surface of the guide member and a crystal deposited on the inner-side surface of the guide member;
a crystal growth termination step of terminating crystal growth by lowering a temperature;
and a gap enlargement step, performed between the single crystal growth step and the crystal growth termination step, of enlarging the gap by maintaining a difference, Pin−Pout, between a partial pressure Pin of Si 2 C in a source gas in the vicinity of an inlet of the gap and a partial pressure Pout of Si 2 C in a source gas in the vicinity of an outlet of the gap, at 0.18 torr or less.
2. The method for producing a silicon carbide single crystal according to claim 1 , wherein the gap enlargement step is performed for at least 5 hours.
3. The method for producing a silicon carbide single crystal according to claim 1 , wherein the gap enlargement step is performed for a period of at least 5% of a time required for the total crystal growth.
4. The method for producing a silicon carbide single crystal according to claim 1 , wherein a silicon carbide single crystal having a length of at least 15 mm is produced.
5. The method for producing a silicon carbide single crystal according to claim 1 , wherein a silicon carbide single crystal is produced at an average growth rate of at least 0.15 mm/h.
6. The method for producing a silicon carbide single crystal according to claim 1 , wherein a temperature difference between the temperature of a source gas in the vicinity of an inlet of the gap and the temperature in the vicinity of an outlet of the gap during the gap enlargement step is smaller than the temperature difference between the temperature of a source gas in the vicinity of an inlet of the gap and the temperature in the vicinity of an outlet of the gap during the single crystal growth step.