Demonstration of 4H-SiC CMOS circuits consisting of well-balanced n- and p-channel MOSFETs fabricated by ultrahigh-temperature gate oxidation

Abstract

Complementary metal-oxide-semiconductor inverters featuring steep voltage-transfer characteristics (VTC) were successfully fabricated on 4H-SiC(0001) substrates. Even without nitridation of the MOS interfaces, well-balanced n- and p-channel field-effect transistors were realized by means of ultrahigh-temperature gate oxidation (HTO) at 1600 °C under reduced oxygen partial pressure. Improvements in the performances of both n- and p-channel SiC metal-oxide-semiconductor field-effect transistors were achieved by subsequently performing forming gas annealing (FGA) at 1200 °C, leading to mostly symmetric VTC with negligible hysteresis. The effect of HTO and subsequent FGA at high temperatures was verified from the stable and improved performance of 23-stage ring oscillators over a wide temperature range.