Nitroxidation of H-Terminated Si(111) Surfaces with Nitrobenzene and Nitrosobenzene

Ultrathin silicon oxynitride films have attracted substantial attention as gate dielectrics. In this work, we investigate a wet-chemistry approach to introduce a monolayer silicon oxynitride film by reacting H-terminated Si(111) surface with nitro- or nitrosobenzene. The bifunctional aromatic molecules serve as a source of oxygen and nitrogen, while phenyl ring remains intact after the reaction and can be used for further modifications or as a resist. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to confirm surface reaction and to quantify surface coverage. Density functional theory (DFT) cluster calculations were employed to explore feasible reaction pathways, predict the vibrational spectra of possible reaction products, and compare the observed XPS binding energies with calculated N 1s core level energies. Substantial differences in reactions of these two molecules on silicon provide the opportunity to tune the nitroxidation process to achieve the desired levels of oxygen and nitrogen by chemical means at relatively mild conditions.