Hole mobility enhancement and Si cap optimization in nanoscale strained Si1−xGex PMOSFETs

Abstract

P-channel metal-oxide-semiconductor field-effect-transistors (PMOSFETs) with a Si1−xGex/Si heterostructure channel were fabricated. Peak mobility enhancement of about 41% in Si1−xGex channel PMOSFETs was observed compared to Si channel PMOSFETs. Drive current enhancement of about 17% was achieved for 70 nm channel length (LG) Si0.9Ge0.1 PMOSFETs with SiO2 gate dielectric. This shows the impact of increased hole mobility even for ultra-small geometry of MOSFETs and modest Ge mole fractions. Comparable short channel effects were achieved for the buried channel Si1−xGex devices with LG=70 nm, by Si cap optimization, compared to the Si channel devices. Drive current enhancement without significant short channel effects (SCE) and leakage current degradation was observed in this work.