Semiconductor device

Abstract

An n-type low impurity concentration semiconductor layer is provided, by epitaxial growth or the like, on a p-type semiconductor substrate. In order to vertically form a semiconductor device in the low impurity concentration semiconductor layer, at least a p-type diffusion region is provided. In a surface of the semiconductor layer, a collector electrode and a base electrode are respectively formed in electrical connection to the n-type low impurity concentration semiconductor layer and the p-type diffusion region. The collector electrode is formed on a surface of the n+-type low resistance region of a polycrystal semiconductor formed depthwise in the low impurity concentration semiconductor layer. As a result, a semiconductor device is obtained that a low resistance region can be formed without increasing the thickness of an eitaxial growth layer while having less effect of diffusion or the like upon other regions where forming depthwise, for example, a low resistance region called a transistor collector wall in a semiconductor layer to provide connection to an electrode.

Dependencies are inferred from the claim text.