Patent ID: 7037799

Claim:
A method of fabricating a bipolar transistor device comprising: selectively implanting a dopant of n-type conductivity in a substrate; growing an epitaxial layer on the substrate and diffusing a portion of the implanted n-type dopant into the epitaxial layer forming a buried layer, the buried layer being n-type; selectively implanting a dopant of n-type conductivity into the epitaxial layer forming a deep collector, the deep collector being n-type; selectively implanting a dopant of n-type conductivity into the epitaxial layer forming a collector region, the collector region being n-type; selectively implanting a dopant of p-type conductivity within the collector region forming a base region, the base region being p-type, wherein selectively implanting the dopant of p-type conductivity to form the base region comprises performing ion implantation at a first energy/velocity and a first dose; selectively implanting a dopant of n-type conductivity within the base region forming a top region at a surface of the base region, the top region remaining p-type; wherein selectively implanting the dopant of n-type conductivity within the base region forming the top region comprises performing ion implantation at a second velocity and a second dose, the second velocity being about one-third that of the first velocity and the second dose being less than the first dose; and selectively implanting a dopant of n-type conductivity within the base region forming an emitter region, the emitter region being n-type.