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

Poly-Si gated NMOSFETs, with HfO/sub 2//HfSi/sub x/O/sub y/ gate stacks for CMOS low-power application are reported for the first time. Compared to an SiO/sub 2/ control sample, the HfO/sub 2//HfSi/sub x/O/sub y/ stack with equivalent oxide thickness of about 18 /spl Aring/ exhibits four-orders of magnitude reduction in gate leakage at V/sub g/=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 SiO/sub 2/ can be reached.