Method of production of semiconductor device

A method of production of a semiconductor device forming a first semiconductor element comprising a collector region, an emitter region, and an intrinsic base region on a first region and forming a second semiconductor element comprising source/drain regions and a gate electrode on a second region and a sidewall insulating film on side portions of the gate electrode, including the steps of:

• forming said collector region on a semiconductor substrate of said first region;
• forming said gate electrode on a semiconductor substrate of said second region;
• forming said intrinsic base region on said semiconductor substrate of said first region;
• forming an insulating film having an opening at an emitter formation region on said intrinsic base region over said semiconductor substrate of said first and second regions;
• forming an emitter electrode in said opening and near said opening of said insulating film of said first region;
• forming a protective film for suppressing introduction of impurities to said emitter electrode of said first region;
• removing said insulating film of said first and second regions while leaving a sidewall insulating film on said gate electrode side portions and emitter region formation insulating film on a part under said emitter electrode by using said emitter electrode as a mask;
• forming an external base region connected to said intrinsic base region by self-alignment with respect to said emitter electrode over said semiconductor substrate of said first region;
• forming said source/drain regions on said semiconductor substrate of said second region by using said sidewall insulating film as a mask;
• and
• forming said emitter region connected to said intrinsic base region on said semiconductor substrate of said first region under said opening by diffusing an impurity in said intrinsic base region from said emitter electrode via said opening of said emitter region formation insulating film.