Modulation of TiSiN effective work function using high-pressure postmetallization annealing in dilute oxygen ambient

To increase the effective work function of a $W∕TiSiN$ metal gate stack without an equivalent oxide thickness (EOT) increase, we developed a process for high-pressure postmetallization annealing in diluted oxygen ambient. Compared with annealing in an atmospheric pressure, oxygen postmetallization annealing (PMA) in a high-pressure ambient $(1–20atm)$ showed further modulation of the effective work function $(4.6–4.8eV)$ without an EOT increase. These differences can be attributed to total amounts of oxygen supplied to gate stack system. Additionally, the origin of EOT increase after the oxygen PMA was attributed to oxidation of the capping metal.