A method of manufacturing a bipolar transistor.

摘要

A device area (16) is defined in a semiconductor body (10) by forming at one major surface (12, 12a) of the body a step (11) having a side wall (11a) and top surface (11b) bounding the device area 16. A silicon layer (13) is deposited so as to cover the side wall (11a) and top surface (11b) of the step and an adjoining lower surface area (12c). Dopant impurities are introduced so that the side wall silicon region (13a) is shielded from the dopant impurities and the undoped side wall silicon region (13a) is later removed by selective etching. The silicon region (13c) on the lower surface area (12a) adjoining the step (11) is masked and the silicon region (13a) on the top surface (11b) at the step (11) removed to leave the doped silicon region (13c) on the one major surface (12a) for contacting a device region (29), for example the base region of a transistor, of the device area.