Patent ID: 7091099
Filing Date: 2006-08-15
Classification: H01L

Abstract:
1. A method for fabricating a bipolar transistor, comprising the steps of: a) epitaxially growing on a first semiconductor layer of a first conductive type surrounded by isolation layers, a second semiconductor layer having a different band gap from that of the first semiconductor layer and containing an impurity of a second conductivity type so as to extend between the isolation layers; b) epitaxially growing on the second semiconductor layer, a third semiconductor layer having a different band gap from that of the second semiconductor layer; c) forming on the third semiconductor layer, an insulating film having an emitter opening portion; d) forming on the third semiconductor layer and the insulating film, a polysilicon layer containing an impurity of the first conductivity; e) patterning the polycrystalline layer and the insulating film to form an emitter electrode; and f) implanting ions of an impurity of the second conductive type into the second and third semiconductor layers from a direction tilted from a perpendicular direction with respect to a surface of a substrate using the emitter electrode and the insulating film as masks, wherein in the step c), the insulating film is in contact with the upper surface of the third semiconductor layer.