MECHANISM FOR ENHANCED INTERFACIAL DEGRADATION IN ANNEALED SIO2 SI BASED DEVICES/

A mechanism of annealing induced, near interfacial degradation is pres ented which involves the diffusion of O atoms from the oxide into the underlying Si substrate. Neutral oxygen-vacancies are created in the S iO2 network. which may act as positive or negative charge trap sites. Evidence for this diffusion is presented using O-18 as a tracer and st udying the 180 interstitial profile in the Si substrate following anne aling. Calculations performed on the basis of this mechanism assuming a typical thermal budget appropriate to device processing suggest that resultant trap densities greater than or equal to 10(12) cm(-2) are c reated. This value is consistent with densities observed technological ly following electron or hole injection into gate oxides.