Effects of wet oxidation/anneal on interface properties of thermally oxidized SiO2/SiC MOS system and MOSFET's

Effects of wet atmosphere during oxidation and anneal on thermally oxidized p-type and n-type MOS interface properties were systematically investigated far both 4H- and 6H-SiC, Deep interface states and fixed oxide charges were mainly discussed. The wet atmosphere was effective to reduce a negative flatband shift caused by deep donor-type interface states in p-type SIC MOS capacitors. Negative fixed charges, however, appeared near the interface during wet reoxidation anneal. In n-type SIC MOS capacitors, the flatband shift indicated a positive value when using wet atmosphere. The relation between interface properties and characteristics of n-channel planar 6H-SiC metal-oxide-semiconductor held effect transistors (MOSFET's) was also investigated. There was Little relation between the interface properties of p-type MOS capacitors and the channel mobility of;MOSFET's, The threshold voltage of MOSFET's processed by wet reoxidation anneal was higher than that of without reoxidation anneal, A clear relation between the threshold voltage and the channel mobility was observed in MOSFET's fabricated on the same substrate.