Chemical bonding structures of silicon oxynitride films grown by ionised N2 and pure O2 gas mixtures at low temperature

Abstract

The ultrathin silicon oxynitride (SiOxNy) films were formed using the direct oxynitridation of Si using ionised N2 and pure O2 gas mixtures at the relatively low temperature (600°C). The in situ X‐ray photoelectron spectroscopy (XPS) was used to assess the chemical composition and chemical state of the SiOxNy films. N 1s XPS spectra reveals that at least three characteristic N bonding states such as N≡Si3, N–(SiOx)3 and N = Si2–O bonds are formed in the SiOxNy films. As growth time increases, the N–(SiOx)3 bond is dominant in SiOxNy films, although N≡Si3 bonds are mainly formed in the initial growth stage at the temperature of 600°C. As considering the absence of direct bonding between N and O atoms, the nitridation and oxidation processes are believed to proceed independently. The increase in the growth temperature leads to the breakdown of both N–(SiOx)3 and N≡ = Si3 bonds and transformation into N = Si2–O bonding structure.