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

摘要

This work focused on the metal-oxide-semiconductor (MOS) capacitor and extremely thin silicon-on-insulator (ETSOI) p-type MOS field-effect transistor (pMOSFET) 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, similar to 0.77 nm), small hysteresis (Delta V-fb, similar to 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 degrees C to 125 degrees 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 pMOSFET with 25 nm gate length (L-g) also exhibited good electrical properties with switch ratio of 3.2 x 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.