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

Abstract

This work studies the properties of the SiO 2–Si 3N 4 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 Si 3N 4, silicon–silicon bonds at Si 3N 4–thermal SiO 2 interface are found. These excess Si–Si bonds are produced by replacing nitrogen with oxygen during the oxidation of Si 3N 4. We further propose that the Si–Si bonds are the major trap center at the Si 3N 4–SiO 2 interface. With MINDO/3 numerical simulation, we have found that the Si–Si bonds can capture both electrons and holes at the top Si 3N 4–SiO 2 interface. These bonds are proposed to be the responsible candidate for the positive charge accumulation in re-oxidized nitrided oxide.