2000-A/1-mΩ power MOSFETs in wafer repair technique

Power MOSFETs with a current capability of up to several thousand amperes and hence an active device area significantly exceeding the typical IC chip size can be realized only if a wafer repair technique is used. A suitable technique has been developed and used to realize circular power MOSFETs with a diameter of 3 cm. The devices are suited to control up to 2000-A drain current and exhibit an on-resistance of R_DS(on)=0.9 mΩ. To contact such a device, a pressure contact system adequate to the high-current value is used. Typical switching times are about 100 ns. Such a large-area MOSFET was used in a MOSFET-GTO (gate turnoff thyristor) cascode circuit to switch anode currents up to 1200 A/1000 V. The total switching time was significantly reduced, and a smaller snubber capacitor could be employed than with the GTO in a conventional circuit