Method of producing a bipolar transistor

Abstract

A dummy emitter is formed in the portion corresponding to an emitter region, on a multiplayer structural material comprising layers for forming emitter, base and collector, and using it as mask, an external base region is exposed by etching, and a projection of emitter region is formed, while the dummy emitter is inverted into an emitter electrode, thereby forming an emitter electrode metal layer to cover the whole upper surface of the emitter. Using thus formed emitter electrode metal layer, a base electrode metal layer is formed, by self-alignment, adjacently to the emitter. In other method, on a multilayer structural material, impurities are introduced outside the portion corresponding to the base region of a bipolar transistor in order to insulate, at least, the layer to form the emitter, the layer to form the base, or at most, these layers and the layer to form the collector, and an extension type dummy emitter extending from the emitter portion to the insulating region formed by transforming from the semiconductor material to form the emitter and using it as mask, the external base region is exposed to form a projection coupling the emitter region and insulating region, and the dummy emitter is inverted to transform into an emitter electrode metal layer to cover the whole upper surface of the projection.