HIGH-FIELD MOBILITY EFFECTS IN REOXIDIZED NITRIDED OXIDE (ONO) TRANSISTORS

The high-field mobility behavior of silicon MOSFET's fabricated with reoxidized nitrided oxide (ONO) gate dielectrics has been investigated. Measurements have been performed at both room temperature and 77 K on both n- and p-channel FET's for both ONO and conventional SiO2 films. While the peak electron mobility is much higher for standard SiO2, a crossover occurs in the high-field region beyond which ONO transistors exhibit higher mobility. The crossover voltage is reduced at 77 K. Measurements intended to gain further insight into this phenomena suggest that differences in surface roughness scattering, or the buried-channel nature of an ONO NMOS transistor are the most likely explanations for the high-field mobility behavior observed.