Density functional theory study of deep traps in silicon nitride memories

摘要

Using density functional theory, the interaction of hydrogen with a nitrogen vacancy in β-Si_3N_4 is investigated. A single H atom was found to be energetically favorable over non- and doubly protonated vacancies. The traps composed of excess silicon and hydrogen have negative correlation energy which is connected with different distances of Si-H and Si-Si bonds in charged and neutral states. The energy gains after trapping are consistent with trap activation energies in advanced silicon nitride memories. Based on the present results, a model of memory traps is proposed.