22 kV, 1 cm2, 4H-SiC n-IGBTs with improved conductivity modulation

In this paper, we report our recently developed large area 4H-SiC n-IGBTs that have a chip size of 1 cm² and an active conducting area of 0.37 cm². A blocking voltage of 22.6 kV has been demonstrated with a leakage current of 9 μA at a gate bias of 0 V at room-temperature. This is the highest breakdown voltage of a single MOS-controlled semiconductor switch reported to date. To improve the conductivity modulation and lower the conduction losses during the on-state, a thermal oxidation process was applied to enhance the carrier lifetime prior to the device fabrication. Compared to the devices that did not receive this lifetime enhancement process, the lifetime enhanced devices displayed nearly 1 V lower forward voltage drop with little increase in switching energy and no degradation of static blocking characteristics. A specific differential on-resistance of 55 mΩ-cm² at 20 A and 125 °C was achieved, suggesting that bipolar power devices with thick drift regions can benefit from further enhancement of the ambipolar carrier lifetime.