Patent ID: 6933201

Claim:
A method of manufacturing a semiconductor device, comprising steps of: (a) forming an isolation portion in a main surface of a semiconductor substrate; (b) forming a first insulating film over an active region encompassed by the isolation portion of the semiconductor substrate; (c) forming a second insulating film over the main surface of the semiconductor substrate after the step (b); (d) depositing a base electrode formation film over the second insulating film; (e) introducing an oxidation promoting impurity into an upper layer portion of the base electrode formation film; (f) depositing a third insulating film over the base electrode formation film; (g) removing a portion of the third insulating film and base electrode formation film to form a first emitter opening portion; (h) oxidizing the semiconductor substrate to form a fourth insulating film over a side surface of the base electrode formation film and a corner portion thereof on a side in contact with the third insulating film, each inside of the first emitter opening portion; (i) wet-etching the semiconductor substrate to remove the second insulating film through the first emitter opening portion, thereby forming a second emitter opening portion which is opened so that a side surface of the second insulating film is kept apart from the side surface of the base electrode formation film inside of the first emitter opening portion and from which a portion of the base electrode formation film is exposed; (j) washing the resulting semiconductor substrate with hydrofluoric acid to remove the first insulating film exposed from the second emitter opening portion; (k) heat treating the semiconductor substrate in a reducing gas atmosphere; and (l) selectively forming, by the epitaxial method, a heterocrystalline layer over the semiconductor substrate exposed from the second emitter opening portion.