A novel high-k gate dielectric HfLaO for next generation CMOS technology

Abstract

The physical and electrical characteristics of high-k (HK) gate dielectric HfLaO were systematically investigated. Incorporation of La in HfO2 can raise the film crystallization temperature from 400degC to 900degC. Moreover, NMOSFETs fabricated with HfLaO gate dielectric exhibit superior electrical performances in terms of threshold voltage (Vth), bias temperature instability (BTI), channel electron mobility and gate leakage current compared to those fabricated with HfO2 dielectric. Particularly, the authors also report that the effective work function (EWF) of metal gate (MG) can be tuned to a wide enough range to fulfil the requirement of bulk CMOSFETs by employing HfLaO dielectric and n- and p-type metal gates respectively. These advantages are correlated to the enhanced thermal stability and reduction of oxygen vacancy density in HfLaO compared to HfO2, making it a promising high-k gate dielectric to replace SiO2 and SiON to meet the ITRS requirements. Finally, a possible dual metal gate CMOS integration process is proposed