Kinetics of the Slow‐Trapping Instability at the Si / SiO2 Interface

Abstract

The slow-trapping instability can be a potentially major threat to reliability of p-channel enhancement-mode IGFET's. We have determined the kinetics of slow trapping for Al-gate MOS structures on (111) n-Si and evaluated the role of surface states, Nss, for n- and p-type Si of (111) and (100) orientation. Slow trapping, as revealed by negative bias-temperature aging, generates a characteristic distribution of Nss with a peak near the midgap. This effect is responsible for the fact that for n-Si, the threshold shift, ΔVT ≫ ΔVfb, the flatband shift, and for p-Si, ΔVT < ΔVfb- In the regime where ΔVfb is less than the saturation value, our data on slow-trapping kinetics can be represented by the factorial relationship [formula omitted] where VB is the applied negative bias (10-40V), t is the time (10-103 min), T is the temperature (373°-573°K), k is the Boltzmann constant, n = 4.76 - 5.3 × 10-3T, A ~ 1.6 × 103, and ea is the thermal activation energy (~0.64 eV). This equation emphasizes the strong field dependence of ΔVfb at lower temperatures. © 1978, The Electrochemical Society, Inc. All rights reserved.