There is provided a method of fabricating semiconductor devices that allows ion implantation to be performed at high temperature with ions accelerated with high energy to help to introduce dopant in a semiconductor substrate, in particular a SiC semiconductor substrate, at a selected region to sufficient depth. To achieve this the method includes the steps of: providing the semiconductor substrate at a surface thereof with a mask layer including a polyimide resin film, or a SiO2 film and a thin metal film; and introducing dopant ions.