The effect of fluorine in silicon dioxide gate dielectrics

The effect of post-oxide-growth fluorine incorporation in gate dielectrics is reported. Fluorine was introduced through ion implantation into polysilicon and diffused into the gate oxide, as indicated by SIMS measurements. No great decrease in the breakdown field was observed, although a decrease in charge-to-breakdown was seen. Interface characteristics also improved with medium to high doses of fluoride. High doses were found to grow additional oxide. NMOS FETs showed increased immunity to hot-electron-induced stress. These results are explained by a model wherein fluorine bonds to silicon, and the displaced oxygen grows the additional oxide.< >