TEOS-based low-pressure chemical vapor deposition for gate oxides in 4H–SiC MOSFETs using nitric oxide post-deposition annealing

Abstract

The use of SiO2/4H–SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) can be problematic due to high interface state density (Dit) and low field-effect mobility (μfe). Here, we present a tetra-ethyl-ortho-silicate (TEOS)-based low-pressure chemical vapor deposition (LPCVD) method for fabricating the gate oxide of 4H–SiC MOSFETs using nitric oxide post-deposition annealing. SiO2/4H–SiC MOS capacitors and MOSFETs were fabricated using conventional wet and TEOS oxides. The measured effective oxide charge density (Qeff) and Dit of the TEOS-based LPCVD SiO2/4H–SiC MOS capacitor with nitridation were 4.27 × 1011 cm−2 and 2.99 × 1011 cm−2eV−1, respectively. We propose that the oxide breakdown field and barrier height were dependent on the effective Qeff. The measured μfe values of the SiO2/4H–SiC MOSFETs with wet and TEOS oxides after nitridation were, respectively, 11.0 and 17.8 cm2/V due to the stable nitrided interface between SiO2 and 4H–SiC. The proposed gate stack is suitable for 4H–SiC power MOSFETs.