ROOM-TEMPERATURE SI3N4 AND GE3N4 GROWTHS BY SI AND GE SURFACE IRRADIATION WITH A N2 ELECTRON-CYCLOTRON RESONANCE PLASMA - AN X-RAY PHOTOEMISSION-STUDY

An ultrahigh vacuum compatible electron cyclotron resonance (ECR) plasma source is employed for the first time in studying the surface nitridation with N2 on Si (001)-2 X 1 at low substrate temperature (T(s) = RT). The exposure to the efficiently activated and dissociated nitrogen flux in the microwave plasma is not limited to the silicon surface states but results in the formation of ultrathin dielectric near-stoichiometric Si3N4 layers (approximately 20 angstrom) analyzed in situ by x-ray photoelectron spectroscopy (XPS). These films, without hydrogen content and silicon deposit, could easily be grown in few minutes at RT and at relatively low working pressures (approximately 10(-4)mbar in the chamber) without destroying the underlying Si substrate as checked by x-ray photoelectron diffraction (XPD). Composition deviations to the Si3N4 stoichiometry of the grown nitride layers are also discussed in relation with the contamination oxygen content and the contribution of the interface subnitride configurations.