High-k gate stack HfxTi1-xON/SiO2 for SiC MOS devices

Abstract

In order to reduce the electric field in the gate dielectric and thus solve the reliability problem, high dielectric-constant (k ) gate dielectrics HfxTi1-xO2 and HfxTi1-xON were applied in SiC metal-oxide-semiconductor (MOS) devices for the first time. An ultra-thin thermally grown SiO2 was used as an interlayer between SiC and the high-k materials to block electron injection into the low-barrier high-k materials. Incorporating nitrogen (by sputtering in an Ar/N2 ambient) into the hafnium-titanium oxide stacked with a SiO2 interlayer (HfxTi1-x O2/SiO2) resulted in better gate dielectric for MOS capacitor, such as less oxide charges and better interface quality. Incorporation of nitrogen also increased the dielectric constant of the oxide, but caused higher dielectric leakage, which was suppressed by the SiO2 interlayer. © Springer Science+Business Media, LLC 2008.