Method of fabricating a bipolar transistor operable at high speed

摘要

An N type diffusion layer as a collector is formed on a P type silicon substrate, and a field oxide film is formed on this diffusion layer. An MoSi2 film is formed on this field oxide film and a first opening is formed on those field oxide film and MoSi2 film to expose the diffusion layer. An N type layer is selectively epitaxially grown only on the bottom of the first opening. A base layer is formed on the N type layer, the side wall of the first opening and the MoSi2 film. The base layer on the N type layer is formed by epitaxial growth, while the base layer on the side wall of the first opening and the MoSi2 film is formed in a polycrystalline state. A first silicon oxide film is formed on this based layer. The first silicon oxide film is thinner on the polycrystalline base layer than on the epitaxially grown base layer. The first silicon oxide film is subjected to anisotropic etching to expose only the surface of the epitaxially grown base layer. An N type silicon film as an emitter is selectively grown only on this exposed base layer.