Silicon / Silicon oxide / LPCVD Silicon nitride stacks: The effect of oxide thickness on bulk damage and surface passivation

Abstract

Silicon / thermally grown silicon dioxide / LPCVD silicon nitride stacks were formed to investigate the influence of the oxide thickness on silicon bulk and surface properties after thermal processing. With no oxide, the LPCVD silicon nitride layer causes serious irreversible bulk damage to silicon wafers after a high temperature treatment. A thin oxide layer (~10nm) helps to substantially reduce the damage. A thick oxide (more than 50nm) can help completely eliminate the bulk damage. An increase of surface states was indicated by an increase of emitter the saturation current density for the stacks with thin oxide layers after high temperature treatments. Even after a re-growth of thick oxide layer and forming gas anneal, the stacks previously without oxide layer shows a much higher emitter saturation current value, which indicates silicon nitride causes a serious Si-SiO2 interface damage. Keywords: LPCVD, Emitter saturation current, Effective lifetime Show more