Patent ID: 8133791

Claim:
A method of manufacturing a semiconductor device comprising a substrate, a silicon semiconductor body and a bipolar transistor with an emitter region of a first conductivity type, a base region of a second conductivity type opposite to the first conductivity type, and a collector region of the first conductivity type, the method comprising: depositing at least one epitaxial semiconductor layer on the surface of the semiconductor body in which the collector region is to be formed, the base region to be formed in the epitaxial semiconductor layer, forming an etch stop layer on top of the epitaxial semiconductor layer; depositing a silicon low-crystalline semiconductor layer on the etch stop layer; forming a connecting zone of the base region in the semiconductor layer; providing an opening in the low-crystalline semiconductor layer at the location of an emitter region to be formed, the opening extending to the etch stop layer, a portion of the etch stop layer covering the opening; removing an adjoining portion of the etch stop layer by etching, thereby creating a hollow underneath the silicon low-crystalline semiconductor layer adjoining and connected with the opening; and forming a high-crystalline semiconductor layer in the hollow, characterized in that the formation of the high-crystalline semiconductor layer is carried out in such a manner that a part of the surface of the semiconductor body adjoining the opening is kept free from the high-crystalline semiconductor layer.