An analysis of the effect of hydrogen incorporation on electron traps in silicon nitride

The effect of hydrogen incorporation into nitrogen vacancies in silicon nitride on electron trap is analyzed using density functional theory method. A hydrogen atom is attached to a dangling bond which is well separated from other dangling bonds, whereas it is not attached to ones which strongly interact because of lattice distortion. An electron trap level caused by nitrogen vacancy becomes shallow by hydrogen incorporation. An electron is trapped in a deep level created by a silicon dangling bond before hydrogen incorporation, whereas it is trapped in a shallow level created by an anti-bonding state of a siliconsilicon bond after hydrogen incorporation. The simulation results qualitatively explain the experiment in which reduced hydrogen content in silicon nitride shows superior retention characteristics of the programmed state.