Aggressive SiGe Channel Gate Stack Sealing by Remote Oxygen Scavenging: Gate-First pFET Performance and Reliability

摘要

We demonstrate that aggressive gate dielectric scaling in hafnium-based high-k/metal gate p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with biaxially strained silicon germanium channels can be achieved in gate-first integration via remote interfacial SiO_2 scavenging by metal-doped titanium nitride gates. An inversion thickness of 0.86 nm is reached, corresponding to an equivalent oxide thickness (EOT) of 0.45-0.5 nm. Interlayer-scaling-induced threshold voltage increase and hole mobility reduction are studied in detail. We further establish an exponential interlayer thickness dependence of negative bias temperature instability (NBTI). Previously shown to be effective for nFETs, remote oxygen scavenging is an attractive scaling option for dual-channel CMOS.