Comparison of Thermal Gate Oxides on Silicon and Carbon Face P-Type 6H Silicon Carbide

Abstract

Monocrystalline 6H silicon carbide samples (n-type and p-type) with both carbon face and silicon face have been used to investigate gate oxide quality. The oxides were thermally grown in a dry oxygen ambient at 1523 K with or without the addition of TCA (Trichloroethane), or in wet pyrogenic steam at 1473 K. POCI3 doped polysilicon gates were used for electrical characterisation by capacitance-voltage measurements and breakdown field measurements. Large flatband voltage shifts indicate fixed oxide charges up to 10¹³ cm^-2. The incorporation of aluminum in the oxides was monitored using SIMS (Secondary Ion Mass Spectrometry). Surprisingly high signals were interpreted as evidence of an aluminum-Oxygen compound having been formed (ie Al₂O₃).