Achieving Reduced Specific On-Resistance in 1.2 kV SiC Power MOSFETs at Elevated Temperature

Abstract

Power MOSFETs operate at elevated temperatures due to self-heating and hot ambient temperatures. This paper analyzes the increase in on-resistance with temperature for 1.2 kV rated 4H-SiC planar MOSFETs. The impact of various structural parameters are studied using analytical models supported by experimental data. This work defines how to achieve a low ratio [Ron(150°C)/Ron(25°C)] by structural optimization of 1.2 kV SiC planar MOSFETs for the first time. It is found that the inversion mode MOSFETs, fabricated by us in a 6 inch commercial foundry, have a lower ratio [Ron(150°C)/Ron(25°C)] than the accumulation mode MOSFETs, due to a better balance of change in channel and bulk mobility with temperature. Compared with typical commercially available MOSFETs, our fabricated accumulation mode and inversion mode MOSFETs exhibit a lower ratio [Ron(150°C)/Ron(25°C)], resulting in superior HF-FOM [RonxQgd] at 150°C.