Abstract: A process for forming a structure of a high-frequency bipolar transistor on a layer of a semiconductor material with conductivity of a first type. The process includes forming a first shallow base region by implantation along a selected direction of implantation and using a dopant with a second type of conductivity. The region extends from a first surface of the semiconductor material layer and encloses, toward said first surface, an emitter region with conductivity of the first type. In accordance with the invention, the implantation step includes at least one process phase at which the direction of implantation is maintained at a predetermined angle significantly greatly than zero degrees from the direction of a normal line to said first surface. Preferably, the implantation angle is of about 45 degrees.