Patent ID: 6939772

Claim:
A fabrication method of a bipolar transistor, comprising: a step (a) of forming a second semiconductor layer to be a base layer including a second conductive type impurity on a first semiconductor layer that is formed on a substrate to be a collector layer including a first conductive type impurity; a step (b) of forming, on said second semiconductor layer, a third semiconductor layer to be a Si-cap layer, including the second conductive type impurity at an upper surface thereof, through epitaxial growth from a material having a bandgap different from a bandgap of said second semiconductor layer; a step (c) of depositing an insulator film on said substrate after said step (b); a step (d) of forming an opening portion through said insulator film to reach said third semiconductor layer; and a step (e) of forming an emitter diffusion layer in said third semiconductor layer at a region positioned below said opening portion by introducing the first conductive type impurity.