Method for fabricating a bipolar power transistor

Claim 1

A method for fabricating a bipolar power transistor which is made on a first type of heavily doped substrate serving as a collector of said bipolar power transistor, the method comprising the following steps of: forming a first type of doped layer, a first type of lightly doped layer, a second type of lightly doped layer, a second type of doped layer and a barrier layer on said first type of heavily doped substrate sequentially; forming an opening on a position of said barrier layer; using the barrier layer as a mask, a first type of dopant being doped into said second type of doped layer by said opening and being driven in to form a first type of heavily doped region under said barrier layer; using said barrier layer as a mask, forming a recession thereon by etching said second type of doped layer through said opening, said recession extending to said second type of lightly doped layer through said second type of doped layer; doping a first type of dopant into said second type of doped layer and said second type of lightly doped layer in said recession to form a first type of doped region, said first type of doped region surrounding said recession and being adjacent to said first type of heavily doped region; and forming a conductive layer in said recession, and doping a first type of dopant into said conductive layer, whereby said first type of dopant is diffused in said first type of heavily doped region and said first type of doped region to form a first type of diffused region serving as an emitter of said bipolar power transistor, wherein the doping concentration of said first type of diffused region is greater than that of said first type of heavily doped region.

Claim 2

A method for fabricating a bipolar power transistor which is made on a first type of heavily doped substrate serving as a collector of said bipolar power transistor, the method comprising the following steps of: forming a first type of doped layer, a first type of lightly doped layer, a second type of lightly doped layer, a second type of doped layer and a barrier layer on said first type of heavily doped substrate sequentially; forming an opening on a position of said barrier layer; using the barrier layer as a mask, a first type of dopant being doped into said second type of doped layer by said opening and being driven in to form a first type of heavily doped region under said barrier layer; using said barrier layer as a mask, forming a recession thereon by etching said second type of doped layer through said opening, said recession extending to said second type of lightly doped layer through said second type of doped layer; doping a first type of dopant into said second type of doped layer and said second type of lightly doped layer in said recession to form a first type of doped region, said first type of doped region surrounding said recession and being adjacent to said first type of heavily doped region; and forming a conductive layer in said recession, and doping a first type of dopant into said conductive layer, whereby said first type of dopant is diffused in said first type of heavily doped region and said first type of doped region to form a first type of diffused region serving as an emitter of said bipolar power transistor, wherein the doping concentration of said first type of diffused region is greater than that of said first type of heavily doped region.