Abstract: An N.sup.- silicon layer is epitaxially grown on an oxide film with predetermined openings disposed on one main face of an N.sup.+ silicon substrate to form monocrystalline portions on the openings and polycrystalline portions on the oxide film. Ion implantation and thermal annealing is used to convert the polycrystalline portions to P.sup.+ external base regions and form P.sup.+ internal base regions in the monocrystalline portions. Arsenic ions are selectively implanted into the internal base regions to form N.sup.+ emitter regions. Then, base and emitter electrodes are formed on the external base and emitter regions so as to be electrically insulated from one another by an oxide film and a collector electrode is formed on the other main face of the substrate.

Abstract: An n.sup.- silicon layer is epitaxially grown on an oxide film with predetermined openings disposed on one main face of an N.sup.+ silicon substrate to form single crystalline portions on the openings and polycrystalline portions on the oxide film. Ion implantation and thermal annealing is used to convert the polycrystalline portions to P.sup.+ external base regions and form P.sup.+ internal base regions in the single-crystalline portions. Arsenic ions are selectively implanted into the internal base regions to form n.sup.+ emitter regions. Then, base and emitter electrodes are formed on the external base and emitter regions to be electrically insulated from one another by an oxide film and a collector electrode is formed on the other main face of the substrate.