Bidirectional power FET structure is disclosed with high OFF state voltage blocking capability. A shielding electrode is insulated between first and second gate electrodes in a notch between laterally spaced source regions and channel regions joined by a common drift region around the bottom of the notch....http://www.google.de/patents/US4541001?utm_source=gb-gplus-sharePatent US4541001 - Bidirectional power FET with substrate-referenced shield
