Ammonia as a precursor in electron-enhanced nitridation of Si(100)

Electron beam-enhanced nitridation of Si(100) using ammonia as a precursor at 110 K was studied with electron-stimulated desorption, XPS, AES and high-resolution electron energy-loss spectroscopy (HREELS). Hydrogen ion kinetic energy distributions from adsorbed ammonia exhibited a component from NH3(a) at 7.8 eV, from NH2(a) at 5.4 eV and from H(a) at 4 eV. Formation of the nitride following electron beam irradiation of adsorbed ammonia was shown by both N 1s at 398 eV and Si 2p at 102 eV in XPS spectra. From HREELS spectra following electron beam irradiation, we are able to show that the electron beam is highly effective in removal of hydrogen from NHx(a) (x = 3,2) and from the silicon surface. Electron-stimulated desorption of adsorbed hydrogen and dissociation of adsorbed NHx (x = 3,2) are believed to be responsible for enhanced nitridation. Nitride can also form on the surface by irradiating the surface in an ammonia environment at 110 K. A nitride growth rate of 1 Å min−1 was obtained from the bulk Si LVV AES signal intensity attenuation.