Bipolar transistor free from leakage current across thin base region and process of fabrication thereof

摘要

A bipolar transistor includes a base structure (31) in a hollow space (25a) on a single crystal silicon collector region (23a) defined by a silicon oxide layer (25), and the base structure has an extrinsic base (31c/31d) provided around a single crystal silicon emitter region (32a) and an intrinsic base layer (31a/31b) of single crystal silicon germanium decreasing the thickness from a central portion toward an outer periphery so as to decrease dislocation due to thermal stress in a heat treatment for the emitter region (32a).