Novel Vth tuning process for HfO2 CMOS with oxygen-doped TaCx

We have investigated effects of the oxygen doping into TaCx on the effective work function (Φm,eff) in TaCx/SiO2/Si and TaCx/HfO2/Si gate stacks. It has been found for the first time that the threshold voltage (Vth) is tunable within 0.5~0.6V for HfO2 MOSFETs by adjusting the oxygen content within 0~12 at. % in TaCx. Furthermore, it has been shown that unknown oxygen content in TaCx gates is a possible origin of scattering among the Φm.eff data reported.