High-temperature operation of SiC planar ACCUFET

In this paper, we discuss high-temperature characteristics of novel planar vertical MOSFET structures (called ACCUFET's) fabricated from 6H-SiC and 4H-SiC polytypes. A room-temperature specific on-resistance (R-on,R-sp) of of 18 m Omega.cm(2) was measured on the best 6H-SiC device at a logic-level gate drive voltage of only 5 V, which was in excellent agreement with 15 m Omega.cm(2) obtained in simulations, The measured R-on,R-sp for the 6H-SiC ACCUFET is within 2.5x of the drift region resistance which is the best value obtained so far for any high-voltage SiC MOSFET. The forward voltage drop of the best 6H-SiC ACCUFET at 50 A/cm(2) was 0.9 V, which is much less than that of a 1200-V insulated gate bipolar transistor (typically, 3 V for a high-speed device), The R-on,R-sp exhibited a positive temperature coefficient which is extremely desirable, since it allows paralleling of devices and also improves reliability by avoiding current filamentation problems. In contrast, the R-on,R-sp for the best 4H-SiC reduced rapidly with increase in temperature, At room temperature, the unterminated 6H-SiC and 4H-SiC devices had a breakdown voltage of 350 V and 450 V, respectively, with a leakage current of <100 mu A.