Method of growing semiconductor crystal

Abstract

SiC is a very stable substance, and it is difficult to control the condition of a SiC surface to be suitable for crystal growth in conventional Group III nitride crystal growing apparatuses. This problem is solved as follows. The surface of a SiC substrateis rendered into a step-terrace structure by performing a heating process in an atmosphere of HCl gas. The surface of the SiC substrateis then treated sequentially with aqua regia, hydrochloric acid, and hydrofluoric acid. A small amount of silicon oxide film formed on the surface of the SiC substrateis etched so as to form a clean SiC surfaceon the substrate surface. The SiC substrateis then installed in a high-vacuum apparatus and the pressure inside is maintained at ultrahigh vacuum (such as 10to 10Pa). In the ultrahigh vacuum state, a process of irradiating the surface with a Ga atomic beamat time tat temperature of 800° C. or lower and performing a heating treatment at 800° C. or higher is repeated at least once. The temperature is then set to the growth temperature of an AlN film, and the SiC substrate surfaceis initially irradiated with Al atomsin ultrahigh vacuum state, followed by the feeding of N atoms