Study of Hf-Ti-O Thin Film as High- k Gate Dielectric and Application for ETSOI MOSFETs

This work focused on the metal–oxide–semiconductor (MOS) capacitor and extremely thin silicon-on-insulator (ETSOI) p -type MOS field-effect transistor ( p MOSFET) with laminated hafnium and titanium oxide (Hf-Ti-O) thin films as gate dielectric. The electrical behavior of the MOS capacitor shows that the capacitor with Hf-Ti-O gate dielectric has high performance with low equivalent oxide thickness (EOT, ~0.77 nm), small hysteresis (Δ V fb , ~4 mV), and gate current density of 0.33 A/cm 2 at V g = V fb − 1 V. The dominant conduction mechanism of the Hf-Ti-O thin film (25°C to 125°C) was Schottky emission at lower gate voltage (−0.8 V to −0.2 V) and Fowler–Nordheim (F–N) tunneling at higher gate voltage (<−0.8 V). An ETSOI p MOSFET with 25 nm gate length ( L g ) also exhibited good electrical properties with switch ratio of 3.2 × 10 4 , appropriate threshold voltage of −0.16 V, maximum transconductance ( G max ) of 2.63 mS, drain-induced barrier lowering of 53 mV/V, and subthreshold swing of 65 mV/dec.