Characterization of the silicon nitride-thermal oxide interface in oxide-nitride-oxide structures by ELS, XPS, ellipsometry, and numerical simulation

This work studies the properties of the SiO₂-Si₃N₄ interface in oxide-nitride-oxide (ONO) structures by using energy loss spectroscopy, X-ray photoelectron spectroscopy, ellipsometry measurements and numerical simulation. By oxidation the as-deposited Si₃N₄, silicon-silicon bonds at Si₃N₄-thermal SiO₂ interface are found. These excess Si-Si bonds are produced by replacing nitrogen with oxygen during the oxidation of Si₃N₄. We further propose that the Si-Si bonds are the major trap center at the Si₃N₄-SiO₂ interface. With MINDO/3 numerical simulation, we have found that the Si-Si bonds can capture both electrons and holes at the top Si₃N₄-SiO₂ interface. These bonds are proposed to be the responsible candidate for the positive charge accumulation in re-oxidized nitrided oxide. © 1998 Elsevier Science Ltd. All rights reserved.