Method of manufacturing a semiconductor device

摘要

A method of manufacturing a semiconductor device, which comprises the steps of depositing an electric insulation layer on the surface of a semiconductor substrate in which a deeper base region and a shallower base region are diffused; forming in the electric insulation layer an opening for diffusing an emitter region in the deeper base region; coating the shallower base region with a covering layer in which oxygen and an oxygen compound are diffused at a smaller constant than in the electric insulation layer; carrying out heat treatment in an oxidizing atmosphere to diffuse an emitter region in the deeper base region and also to deposit an oxide layer on these portions of the main surface of the substrate which are not coated with the covering layer; and diffusing an emitter region in the shallower base region, and whereby the current-amplifying properties of the respective transistors whose base and emitter regions are diffused with different depths can be easily controlled with high precision.