Fully silicided NiSi gate on La2O3 MOSFETs

Abstract

We have fabricated the fully silicided NiSi on La2O3 for n- and p-MOSFETs. For 900°C fully silicided CoSi2 on La2O3 gate dielectric with 1.5 nm EOT, the gate dielectric has large leakage current by possible excess Co diffusion at high silicidation temperature. In sharp contrast, very low gate leakage current density of 2 × 10-4 A/cm2 at 1 V is measured for 400°C formed fully silicided NiSi and comparable with Al gate. The extracted work function of NiSi was 4.42 eV, and the corresponding threshold voltages are 0.12 and -0.70 V for respective n- and p-MOSFETs. Electron and hole mobilities of 156 and 44 cm2/V-s are obtained for respective n- and p-MOSFETs, which are comparable with the HfO2 MOSFETs without using H2 annealing.