Interface properties of SiC MOS devices with NH₃ plasma nitridation of ultrathin SiO₂ interfacial layer

Abstract The effect of NH 3 remote-plasma treatment on 4H-SiC surfaces on the interface properties is investigated. By comparing with the N 2 plasma treatment, the NH 3 plasma treatment showed a reduction in interface state density (D it ) down to 3.0 × 10 11 cm −2 eV −1 , with better bias stress stability. The improvement was further enhanced to 1.4 × 10 11 cm −2 eV −1 when the plasma treatment was conducted to the 4H-SiC surface with a 0.4-nm-thick SiO 2 interfacial layer, presumably suppressing the plasma damage to the SiC surface. Mobility improvement from 22.8 to 27.1 cm 2 V −1 s −1 was achieved without negatively shifting the threshold voltage while keeping a high breakdown field of over 10 MV cm −1 .