X-ray photoelectron spectroscopy of gate-quality silicon oxynitride films produced by annealing plasma-nitrided Si(100) in nitrous oxide

Ultrathin silicon oxynitride films with thickness in the range of 1.8-3.5 n m have been produced on Si(100) by nitridation of an NO-oxidized surface wi th an electron-cyclotron resonance plasma source. The films were annealed i n N2O at 950 degreesC for times up to 60 s and formed into Al-gated capacit ors for capacitance-voltage (CV) and current-voltage analysis. The rapid an nealing increases the oxygen content of the films but results in capacitors with excellent electrical properties. For a plasma oxynitride with equival ent oxide thickness, t(eq) = 1.8 nm. current reductions of similar to 20 ov er that for SiO2 films have been obtained for gate voltages in the range 1- 1.5 V. For comparison, the thickness of the oxynitrides was obtained by X-r ay photoelectron spectroscopy of the Si 2p, N 1s, and O 1s photoelectrons. By analyzing the yield from thick silicon dioxide and silicon nitride films , the electron escape depth in silicon nitride was estimated to be 1.7 nm f or the Si 2p electrons. By correcting the measurements of the oxygen/nitrog en concentration ratio obtained from the O 1s and N 1s XPS peaks, and calcu lating the dielectric constant with a Bruggeman effective medium approximat ion, the equivalent oxide thickness was calculated. Agreement to similar to 0.2 nm was obtained with t(eq) determined by the CV analysis. Information o btained from the XPS analysis can also give information about bonding confi gurations and possible errors due to nonuniform stoichiometry as a function of depth. (C) 2001 The Electrochemical Society.