Abstract: A method of manufacturing a semiconductor device involves the step of carrying out the implantation of an impurity in the main plane of a GaAs substrate for the simultaneous formation of a plurality of regions. When the angles formed with the perpendicular implantation of silicon ions in the GaAs main plane and the main orientations of GaAs substrate are expressed by the Euler angles (.lambda.,.mu.,.theta.), then the crystal orientation is so prescribed as to satisfy the following conditions:11.degree.<.lambda.<33.degree.7.degree.<.mu.<24.degree..theta..apprxeq.0.degree.,thereby suppressing the occurrence of channeling in the implantation of ions in the substrate main plane and consequently ensuring substantially uniform impurity concentration in the plural regions.