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A method of fabricating a vertical bipolar semiconductor device includes a step of forming an N--type silicon epitaxial layer which constitutes a part of a collector region and a P+-type polycrystalline silicon film which functions as a base lead-out electrode. The silicon epitaxial layer and the po

A method of fabricating a vertical bipolar semiconductor device includes a step of forming an N--type silicon epitaxial layer which constitutes a part of a collector region and a P+-type polycrystalline silicon film which functions as a base lead-out electrode. The silicon epitaxial layer and the polycrystalline silicon film are insulated by a silicon oxide film which is a sufficiently thick insulating film, covers the silicon epitaxial layer and has an opening. In this opening, by selective growth of a first and a second semiconductor film and ion implantation using a first insulating film spacer, there are formed a P--type single crystal silicon layer, a P+-type polycrystalline silicon film, a P+type single crystal silicon layer (intrinsic base region), a P+-type polycrystalline silicon film, and an N-type single crystal silicon layer. It is possible to reduce the parasitic capacitance between the base region and the collector region without sacrificing the enhancement of the cut-off frequency fT.

대표청구항 ▼

A method for fabricating a semiconductor device, said method comprising the steps of: forming a single crystal silicon substrate of a first conductivity type, which has a buried layer of a second conductivity type provided selectively on a surface of said substrate and which is selectively covered a

A method for fabricating a semiconductor device, said method comprising the steps of: forming a single crystal silicon substrate of a first conductivity type, which has a buried layer of a second conductivity type provided selectively on a surface of said substrate and which is selectively covered at the surface thereof by a silicon epitaxial layer of a second conductivity type; forming a first single crystal semiconductor layer of the second conductivity type, which has an upper surface at a position higher than an upper surface of said silicon epitaxial layer and which extends to said buried layer through said silicon epitaxial layer at a region; forming a first insulating film which has an opening having a first width from an upper surface end portion of said first single crystal semiconductor layer and which covers said silicon epitaxial layer; forming a second single crystal semiconductor layer of the first conductivity type which is provided in said opening, which has an upper surface coincident with an upper surface of said first single crystal semiconductor layer and which covers the upper surface of said silicon epitaxial layer; forming a base lead-out electrode which partly contains a first polycrystalline semiconductor film of the first conductivity type covering an upper surface of said first insulating film and which has an overhang portion having a second width inside said opening; forming a second insulating film which partly covers an upper surface of said base lead-out electrode immediately above said opening and a side surface of which immediately above said opening is disposed in the same plane as a side surface of said base lead-out electrode; forming a first insulating film spacer constituted by a third insulating film, a lower surface of which substantially coincides in height with a lower surface of said base lead-out electrode, which has a width equal to a difference between said first width and said second width, and which covers side surfaces of said base lead-out electrode and said second insulating film; forming a second polycrystalline semiconductor film of the first conductivity type, which covers a lower surface of said first polycrystalline semiconductor film at said overhang portion; forming a third polycrystalline semiconductor film which covers a lower surface of said second polycrystalline semiconductor film; forming a third single crystal semiconductor layer of the first conductivity type, an upper surface of which is partly connected to a lower surface of said third polycrystalline semiconductor film, and a lower surface of which covers said first single crystal semiconductor layer and said second single crystal semiconductor layer; forming a second insulating film spacer constituted by a fourth insulating film, which covers a part of lower surface of said third polycrystalline semiconductor film, a part of upper surface of said third single crystal semiconductor layer, a lower surface of said first insulating film spacer, and a part of side surface of said first insulating film spacer; and forming a fourth single crystal semiconductor layer of the second conductivity type, which fills an air gap defined by said second insulating film spacer and which covers an upper surface of said third single crystal semiconductor layer.