Patent ID: 8361227
Filing Date: 2013-01-29
Classification: C30B

Abstract:
1. A crystal growth method comprising: (a) providing an enclosed growth crucible inside of a growth chamber with a thermal insulation disposed therebetween, the growth crucible having polycrystalline source material and a seed crystal disposed in spaced relation therein; (b) heating the interior of the growth crucible such that a temperature gradient forms between the source material and the seed crystal, the source material is heated to a sublimation temperature and the temperature gradient is sufficient to cause sublimated source material to be transported to the seed crystal where the sublimated source material precipitates on the seed crystal; and (c) causing a gas mixture to flow directly into the growth crucible and into a gap between the polycrystalline source material in the growth crucible and an interior surface of the growth crucible, whereupon the gas mixture reacts with an unwanted element in the body of the growth crucible to form a gaseous byproduct which, under the influence of the gas mixture flowing directly into the growth crucible, flows through a body of the growth crucible to the exterior of the growth crucible, which is formed of a material that is permeable to the gas mixture and the gaseous byproduct, under the influence of the flow of the gas mixture into the growth crucible, wherein the unwanted element is boron and the gas mixture comprises the combination of (a) halosilane gas and (b) an inert gas.