An insulated gate bipolar transistor has a P-type well region which is partially formed in a surface of an N.sup.- -type epitaxial layer formd on a P.sup.+ -type semiconductor substrate. An N.sup.+ -type emitter region is partially formed in a surface of the well region. A buried emitter electrode is...http://www.google.com/patents/US5160985?utm_source=gb-gplus-sharePatent US5160985 - Insulated gate bipolar transistor
