Method for reducing residual stresses in crystals

Claim 1

Method for growing a crystalline body of a selected material from a melt of the same comprising: (a) establishing a melt/solid growth interface between a seed crystal and a melt which is located at the upper end of a capillary die and is replenished by said die, growing a crystalline body and drawing said growing crystalline body progressively from said interface along a predetermined axis, passing said crystalline body through a cooling zone having a temperature profile determined at least in part by a block of heat-conductive material closely confronting and defining a passageway for said growing body and insulation means surrounding said heat-conductive material for causing conduction to be at the predominant heat flow process at all points along the length of said block of heat conductive material, said block of heat-conductive material having at one end thereof closest to said growth interface a temperature which is below the melting point of said selected material but is at a level above the maximum temperature at which significant plastic flow cannot occur in said body of selected material, said block of heat-conductive material having at the opposite end thereof furthest from said growth interface a temperature below said maximum temperature; progressively reducing the temperature of said growing body in said cooling zone in accordance with temperature profile established by said heat-conductive material, and thereafter passing said crystalline body through a secondary cooling zone for reducing its temperature to substantially room temperature.