Patent ID: 8735289

Claim:
A method for manufacturing a bipolar transistor, comprising: providing a semiconductor substrate having a first surface; forming a first insulating layer on the first surface of the semiconductor substrate; forming a mask layer having a first opening on the first insulating layer, the mask layer comprising an electrically conductive material, the first opening of the mask layer defining a location of a first doping region to be formed in the semiconductor substrate, the first doping region being an emitter region of the bipolar transistor; performing a first implantation step using the mask layer as an implantation mask to form the first doping region in the semiconductor substrate; etching the first insulating layer selectively with respect to the mask layer to expose a portion of the first doping region by forming a first opening in the first insulating layer using the mask layer as an etching mask; forming a second insulating layer on the mask layer to cover the first opening in the mask layer, the material of the first and second insulating layers being selectively etchable with respect to the material of the mask layer; forming an etching mask on the second insulating layer for defining at least a first opening in the second insulating layer above the first opening of the mask layer; etching the second insulating layer selectively with respect to the etching mask and the mask layer to form the first opening in the second insulating layer, the first opening of the second insulating layer exposing the first opening in the mask layer; and depositing a conductive material to form at least one contact element disposed in the first opening formed in the first insulating layer, the first opening formed in the second insulating layer and the first opening formed in the mask layer, the contact element being in contact with the first doping region and the mask layer and forming an emitter contact of the bipolar transistor.