Internal Photoemission Study on Reliability of Ultra-thin Zirconium Oxide Films on Strained-Si

As scaling laws become less effective in boosting performance for CMOS devices for 90 nm and below, substrate- and process-induced strain engineering are playing an ever increasing role in performance enhancement. Strained-Si MOSFETs are also attractive for high speed and low power applications (Maiti et al., 2007). Ultra thin SiO₂ gate dielectrics, of less than 1.5 nm in thickness, are needed for the 45 nm technology node and beyond. In order to reduce the leakage current, an extensive search for alternative high dielectric constant (high-k) gate materials that would probably replace the SiO₂ for the sub-45 nm CMOS technologies is being pursued. In this article, we report for the first time, the results of the internal photoemission (IPE) study on reliability properties of microwave-plasma deposited high-k gate dielectric (ZrO₂) films on strained-Si/SiGe heterolayers. The kinetics of charge trapping/detrapping and its chemical nature have been investigated through IPE and electron paramagnetic resonance study.