High-Temperature Recessed Channel SiC CMOS Inverters and Ring Oscillators

Digital electronics in SiC find use in high-temperature applications. The objective of this study was to fabricate SiC CMOS without using ion implantation. In this letter, we present a recessed channel CMOS process. Selective doping is achieved by etching epitaxial layers into mesas. A deposited SiO₂-film, post-annealed at low temperature and re-oxidized in pyrogenic steam, is used as the gate oxide to produce a conformal gate oxide over the non-planar topography. PMOS, NMOS, inverters, and ring oscillators are characterized at 200°C. The PMOS requires reduced threshold voltage in order to enable long-term reliability. This result demonstrates that it is possible to fabricate SiC CMOS without ion implantation and by low-temperature processing.