VFB Roll-off in HfO2 Gate Stack after High Temperature Annealing Process - A Crucial Role of Out-diffused Oxygen from HfO2 to Si

摘要

We report for the first time that VFB roll-off behavior observed in thinner EOT region for metal/HfO2/SiO2 stacks is directly related to re-oxidation at the bottom SiO2/Si interface. Based on this understanding, we propose a possible solution for keeping high effective work-function (驴m,eff) without VFB roll-off and demonstrate the obtained 驴m,eff value of 4.9eV in Pt3Si/HfO2/SiO2 stack.