Effects of In Situ $\hbox{O}_{2}$ Plasma Treatment on off-State Leakage and Reliability in Metal-Gate/High- $k$ Dielectric MOSFETs

The effects of in situ $ \hbox{O}_{2}$ plasma treatment on device characteristics and reliability of metal-gate/high- $k$ devices are investigated systematically. It was found that the $\hbox{O}_{2}$ plasma treatment can be employed for mitigating the formation of a leakage path between the high-$k$ dielectric and the capping nitride layer. It also did not change the threshold voltage $(V_{\rm th})$, carrier mobility, or equivalent oxide thickness. Compared with the control samples, the $\hbox{O}_{2}$ plasma-treated samples achieved a 20-times lower off-state current and enhanced hot-carrier-injection stress immunity.