Systematic Gate Stack Optimization to Maximize Mobility with HfSiON EOT Scaling

A systematic study to optimize gate stack constituents (interface, high- K, metal gate) to maximize carrier mobility with aggressively scaled equivalent oxide thickness (EOT) is presented. We identify ultra-thin thermal oxide, atomic layer deposited HfSiON and optimized plasma nitridation performed in sequence as the optimized run path for sub-nm EOT scaling with high carrier mobility. A metal gate deposition process that minimizes the incorporation of impurities in HfSiON is also vital to maintaining good mobility at low EOTs