Patent ID: 7105415

Claim:
A method for the production of a bipolar transistor having the steps of: (a) providing a semiconductor substrate with a collector region of a first conduction type embedded therein, said collector region being bare toward the top; (b) providing a monocrystalline base foundation region of the second conduction type and an optional monocrystalline base cap region of the first or second conduction type as a base region above the collector region; (c) providing a base terminal region of the second conduction type above the base region; (d) providing a first insulation region above the base terminal region; (e) forming a window in the insulation region and base terminal region for the purpose of at least partly uncovering the base region; (f) providing a first insulating sidewall spacer in the window for the purpose of insulating the base terminal region; (g) removing a natural oxide in the uncovered base region; (h) depositing differentially and patterning an emitter layer which forms a monocrystalline emitter region above the base region and a polycrystalline emitter region above the first insulation region and the first sidewall spacer; and (i) carrying out a heat treatment step for the purpose of partly driving the crystalline emitter region into the base region and for the purpose of forming an enlarged crystalline emitter region.