Patent ID: 6905934

Claim:
A method for manufacturing a semiconductor device comprising the steps of: (a) depositing a silicon nitride film on a semiconductor substrate; (b) depositing a base electrode forming silicon film of a bipolar transistor on the silicon nitride film; (c) depositing a first silicon oxide film on the base electrode forming silicon film; (d) forming an aperture that reaches the silicon nitride film on the first silicon oxide film and the base electrode forming silicon film; (e) forming a second silicon oxide film on the side surface of the base electrode forming silicon film that is exposed from the aperture by applying a first oxidation treatment on the semiconductor substrate; (f) etching and removing the silicon nitride film in isotropic fashion so that a side surface of the silicon nitride film is recessed from a side surface of the base electrode forming silicon film in the aperture by applying wet etching treatment on the silicon nitride film; and (g) forming a base region forming epitaxial layer selectively on the semiconductor substrate that is exposed from the aperture, wherein said aperture is filled without performing a second oxidation treatment on the substrate.