Physical Modeling the Impact of Self-Heating on Hot-Carrier Degradation in pNWFETs

Abstract

We develop and validate a physics-based modeling framework for coupled hot-carrier degradation (HCD) and self-heating (SH). Within this framework, we obtain the lattice temperature distribution throughout the device by solving the lattice heat flow equation coupled with the drift-diffusion approach. Then, the evaluated temperature spatial profile in the transistor is taken into account while solving the Boltzmann transport equation for carriers to obtain the carrier energy distribution functions, which are needed to compute the rates of the single- and multiple-carrier mechanisms of bond dissociation. The effect of SH on HCD is threefold: (i) it results in a significant distortion of the carrier distribution function, (ii) device heating decreases vibrational lifetime of the Si-H bond, thereby suppressing the multiple-carrier mechanism, and (iii) the rate of thermal bond-breakage becomes higher due to SH. The model is capable of accurately reproducing relative changes in the saturation drain current with stress time measured in p-channel nanowire field-effect transistors subjected to HCD under different stress conditions. We show that neglecting SH leads to substantial underestimation of HCD.