Work function tuning of the TixTayN metal gate electrode for advanced metal-oxide-semiconductor devices applications

A work function (WF) tuning of the TixTayN metal gate ranging from 4.1to4.8eV has been observed using a post-metal-annealing (PMA). The mechanism related to the effective tunable WF can be explained using the creation of the extrinsic states, which is usually associated with the bonding defects that formed at the TixTayN∕SiO2 interface. The results display that the electron trapping is generated in the gate dielectric during the PMA treatments. The reduction on equivalent-oxide thickness with increasing the PMA temperature can be attributed to the combination of the densification of the SiO2 and the high-k layer that formed at the TixTayN∕SiO2 interface.