Semiconductor device

Abstract

A bipolar transistor including a first collector layer, a second collector layer, a base layer, and an emitter layer is disposed on a substrate. Etching characteristics of the second collector layer are different from etching characteristics of the first collector layer and the base layer. In plan view, an edge of an interface between the first collector layer and the second collector layer is disposed inside an edge of a lower surface of the base layer, and an edge of an upper surface of the second collector layer coincides with the edge of the lower surface of the base layer or is disposed inside the edge of the lower surface of the base layer.

Dependencies are inferred from the claim text.