Intrinsic Reliability Improvement in Biaxially Strained SiGe p-MOSFETs

In this letter, we show an improvement not only in performance but also in reliability of a 30-nm-thick biaxially strained SiGe (20% Ge) channel on Si p-type metal-oxide semiconductor field-effect transistors. Compared with a Si chan nel, a strained SiGe channel allows larger hole mobility μ_h in the transport direction and alleviates charge flow toward the gate oxide. μ_h enhancement by 40% in SiGe and 100% in Si-cap/SiGe is observed compared with Si hole universal mobility. A ~40% reduction in negative-bias temperature instability degradation, gate leakage, and flicker noise is observed, which is attributed to a 4% increase in the hole-oxide barrier height φ in SiGe. A similar field acceleration factor Γ for the threshold voltage shift Δ_VG and an increase in noise ΔS_VG m Si and SiGe suggest identical degradation mechanisms.