To provide the structure of a semiconductor device provided with a deep trench and a method for manufacturing the semiconductor device in the small number of processes.

A bipolar transistor provided with an N type collector area 4, an intrinsic base area 6, an external base area 7, a collector lead out part 4, and an emitter area 12 is formed on an element area segmented by a field oxide film 2 and a nitride film 13 to be a silicon etching stopper is formed on the element area including not only an emitter electrode 10 but also the collector lead out part 4 and the external base area 7. In the case of opening a contact 16 on a BPSG 14 formed on the upper layer of the nitride film 13, a trench part 17 is formed by using the nitride film 13 by engraving a silicon substrate 1 to prescribed depth through the BPSG 14 and the field oxide film 2. Since the contact 16 and the trench part 17 are simultaneously formed, the number of manufacturing processes can be sharply reduced.