HfO2∕HfSixOy high-K gate stack with very low leakage current for low-power poly-Si gated CMOS application

Abstract

Poly-Si gated NMOSFETs, with HfO2/HfSixOy gate stacks for CMOS low-power application are reported for the first time. Compared to an SiO2 control sample, the HfO2/HfSixOy stack with equivalent oxide thickness of about 18 Å exhibits four-orders of magnitude reduction in gate leakage at Vg=1 V. Additionally, negligible hysteresis and comparable subthreshold swing are observed, indicating good interface quality and bulk film properties. Furthermore, the stack-caused inherent transconductance degradation is small; almost 66% of the normalised peak transconductance with respect to SiO2 can be reached.