SEMICONDUCTOR DEVICE COMPRISING AN INSULATED GATE BIPOLAR TRANSISTOR AND A FREE-WHEEL DIODE

摘要

This invention relates to an insulated gate bipolar transistor, a semiconductor device using such a transistor and manufacturing methods of these, and in particular, its object is to eliminate the necessity of connection to a freewheel diode used for bypassing a circulating current. In order to achieve this object, the concentration of impurities of an N<+> buffer layer (12) that forms a junction with a P<+> collector layer (11) is increased so that it is possible to reduce an avalanche breakdown voltage of a parasitic diode (D) formed by an N base layer (12, 13) and the P<+> collector layer (11). Thus, the reverse voltage resistance of an IGBT (101) is lowered to not more than 5 times the collector-emitter saturated voltage (VCE(sat)).