(Invited) Orientation Dependence of the Hole Ballistic Velocity in Si, Sige, and Ge Thin-Body Structures with Uniaxial Compressive Strain

Abstract

Uniaxial compressive strain of p-MOSFETs has significantly improved p-MOS performance since it was introduced into high-volume manufacturing in Intel's 90-nm node. Further increases in compressive strain and the Ge fraction of the Si1-xGex channel at successive technology nodes have led to increased hole mobility (and, therefore, increased hole ballistic velocity) in p-MOSFETs over time. While the hole mobility improvement for uniaxial compressive strain along a [110] channel (with a (001) wafer surface) is widely known, the orientation dependence of uniaxial strain on the hole ballistic for arbitrary channel and surface directions has received less attention. In this talk, we use quantum-mechanical strain-dependent 6×6 k·p band-structure simulations to provide a comprehensive theoretical analysis of the impact of crystallographic orientation of the uniaxial strain, channel, and surface direction on the average hole ballistic velocity in thin-body structures of Si, SiGe, and Ge.