Work function engineering by FUSI and its impact on the performance and reliability of oxynitride and Hf-silicate based MOSFETs

In this work, we report an extensive characterisation of fully silicided gate (FUSI) devices with oxynitride (SiON) and Hf-silicate gate dielectrics. Enhanced drive current is obtained, in comparison with poly gate devices, together with an increase in electron/hole mobility and reduction in CET values. We show that the work function (WF) can be engineered by doping of the poly gates prior to FUSI for SiON devices but not for Hf-silicate devices. With reference to the poly gate, Hf-silicate/FUSI devices exhibit improved TDDB reliability behavior, having higher acceleration factor (γ) values. NBTI gives a maximum operating voltage above 1.2 V for ΔV_T = 10% or 30 mV, as extrapolated for a 10 years-lifetime.