Effects of gate metals on interface effects in metal oxide semiconductor systems after electron trapping

Abstract

In the study of electron trapping in silicon dioxide, a turn-around effect in the flatband voltage shift as a function of injected electrons has been reported. Most of the reported work was on capacitors with aluminum gates. When polycrystalline silicon gates were used, very little electron trapping and turn-around effect was observed. The difference was explained by the decrease in the density of water related traps after the additional high temperature process in polycrystalline silicon deposition and doping. In the present experiment, gate metals other than aluminum were used. It was shown that even though the density of electron traps was not changed significantly, a large turn-around effect was only observed when the aluminum gate was used. This result seems to imply that aluminum is mostly responsible for the slow state generation and turn-around effect.