Patent ID: 6436781
Filing Date: 2002-08-20
Classification: H01L

Abstract:
A method for fabricating a semiconductor device comprising, in the listed sequence, the steps of:forming a silicon material having a high concentration buried layer and a low concentration surface region; forming a first insulating film on said silicon material; depositing a polysilicon base electrode; removing said undesired polysilicon by photolithography and anisotropic dry etching; covering the whole surface with a second insulating film having a different substance from that of said first insulating film; opening an aperture in said second insulating film and said polysilicon base electrode; implanting phosphorous ions to form a first collector region; forming a third insulating film having the same substance as that of said second insulating film; etching back said third insulating film by a thickness deposited just before to expose said first insulating film in a region over the first collector region; etching said first insulating film in the lateral direction to expose said silicon material and a lower surface of said polysilicon base electrode; forming an intrinsic base and a polycrystalline outer base for connecting said intrinsic base with said polysilicon base electrode by selective crystal growth; and implanting phosphorous ions to form a second collector region.