Study of inversion layer mobility in metal-oxide-semiconductor field-effect transistors with reoxidized nitrided oxides

The carrier effective mobility μeff in the inversion layer for both n- and p-channel metal-oxide-semiconductor field-effect transistors with ultrathin gate dielectrics prepared by rapid thermal reoxidation (RTO) of rapid thermal nitrided (RTN) SiO2 has been studied. It is found that although RTN/RTO degraded the low-field μeff, it improved significantly the electron μeff under high normal field compared to control SiO2. The effect of RTN/RTO on the hole effective mobility has also been examined and found to be quite different than on the electron effective mobility. A physical mechanism is discussed to account for the observation.