A large area MOS-GTO with wafer-repair technique

Turn-off thyristors with MOS-controlled emitter-base shorts (MOS-GTOs) are fabricated by using IC technology. Therefore, the device area is limited to about 1 cm². However, typical power devices for currents >100 amps need to have areas well above this value. We now succeeded in realizing a MOS-GTO of 3 cm diameter by applying a laboratory type wafer repair technique. Processing failures, like shorts of some kind, are treated in a way which keeps this failures electrical inactive. These devices are comparable to conventional thyristors in their on-state and blocking behaviour. Turn-off currents of about 700 amps can be achieved at low anode-voltages. However, at high anode-voltages the turnoff ability is limited by avalanche injection phenomena.