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

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 (V_th), 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