Punch-through IGBTs with homogeneous n-base operating at 4 kV line voltage

Insulated Gate Bipolar Transistors (IGBTs) for snubberless operation at 4 kV line voltage in inductively loaded circuits have been developed, fabricated and characterized. The key point in the development of these high voltage devices is the Punch-Through (PT) structure which makes use of homogeneous wafer material for the n-base layer combined with a buffer layer diffused from the backside instead of double epitaxial material conventionally used in PT structures. The anode is equipped with emitter shorts to reduce the switching losses. The on-state voltage of the IGBTs is between 2.2 V and 3.4 V at 100 A cm/sup -2/ dependent on the buffer layer implant dose. The leakage current of these devices is less than 8/spl middot/10/sup -6/ A cm/sup -2/ at 5 kV blocking voltage and at room temperature. It was demonstrated that these IGBTs are able to turn off a current density of 50 A cm/sup -2/ at a line voltage of 4 kV in about 5 /spl mu/s under inductive load without any snubber, thereby producing a turn-off energy density of 220 mJ cm/sup -2/.