Patent ID: 9017629
Filing Date: 2015-04-28
Classification: C30B,H01L

Abstract:
1. A method of growing a crystal inside a crystal growth chamber, said method comprising: (a) providing a crystal growth chamber having therein at least one component formed of a material that absorbs at least one gas that is a donor impurity in the growth of crystals in the chamber, said chamber further including therein a source material and a seed crystal; (b) heating the interior of the chamber to a first, elevated temperature in the presence of a first pressure whereupon the combination of the first temperature and the first pressure is sufficient to degas the at least one gas from the component; (c) exposing the interior of the chamber to an inert gas at a second, elevated temperature in the presence of a second pressure, wherein the second temperature is higher than the first temperature and higher than a third, desired crystal growth temperature which is also higher than the first temperature, and the second pressure is greater than the first pressure; (d) reducing the inert gas pressure in the chamber to a third pressure that is between the first pressure and the second pressure; and (e) lowering the temperature inside the chamber to the third, desired crystal growth temperature whereupon the source material sublimates (changes from a solid into a vapor) and the vapor from said sublimation deposits on the seed crystal, wherein each of the first, second and third temperatures is established by controlled heating of the interior of the chamber.