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. (C) 1998 Elsevier Science Ltd. All rights reserved.