Effects of composition and thickness of TiN metal gate on the equivalent oxide thickness and flat-band voltage in metal oxide semiconductor devices

Abstract

We investigated the effects of gas flow rates during sputtering and thickness of TiN metal gate on the equivalent oxide thickness (EOT) and flat band voltage (VFB) in the gate-first (GF) processed metal oxide semiconductor (MOS) devices with HfO2 and HfSiON-based gate dielectrics. For both HfO2 and HfiSON devices, more metallic TiN causes thinner EOT with lower VFB while higher VFB is observed along with thicker EOT for nitrogen-rich TiN case. Also, thicker TiN induces more positive VFB shift. However, for HfSiON, amount of VFB shift and EOT reduction is smaller than those of HfO2-based device, resulting from stronger immunity of Hf-Si bonding against oxygen vacancy generation during thermal process.