Simulations of Self-Heating Effects in SiGe pFinFETs Based on Self-Consistent Solution of Carrier/Phonon BTE Coupled System

Using the in-house simulation tool, self-heating (SH) effects on transport of holes in SiGe pFinFETs are simulated. The coupled system of Boltzmann Transport Equation (BTE) for holes and phonons is solved self-consistently. For transport of holes, the multi subband BTE (MSBTE) is solved for 1D hole gas system, where the subband structure is computed from the 2D $\vec{k} \cdot \vec{p}$ Schrodinger Equation (SE)/3D Poisson equation (PE) solution. For transport of phonons, the BTE for 4 phonon modes (LA, TA, LO, TO) in 3D $\vec{k}$–space is solved based on first order spherical harmonic expansion (SHE) method. This study demonstrates the strong dependence of pMOS SH on Ge content. As Ge mole fraction increases above 0.2, alloy scattering hampers the thermal conductivity by more than one order of magnitude. Combined with boundary scattering and smaller band-gap of SiGe, this effect may pose some alarms on next generation pMOS devices.