Patent ID: 7338555
Filing Date: 2008-03-04
Classification: C23C,C30B

Abstract:
1. A process for producing a highly crystalline aluminum nitride multi-layered substrate by nitriding a single-crystal α-alumina substrate in the presence of carbon, nitrogen and carbon monoxide to form a crystalline aluminum oxynitride layer and a highly crystalline aluminum nitride film as an outermost layer directly on the crystalline aluminum oxynitride layer, said highly crystalline aluminum nitride film as an outermost layer having a film surface smoothness in terms of Ra and RMS of 100 nm or less, wherein nitriding is carried out under reaction conditions which satisfy the following conditions a to d: a: the equilibrium partial pressure of Al b: the equilibrium partial pressure of Al c: the reaction formula (3) proceeds to the right side: wherein alon (AlNsat.) means aluminum oxynitride which is saturated aluminum nitride, and d: the reaction temperature is 1,630° C. (1,903K) or higher and lower than 1,700° C. (1,973K).