Use of an electron cyclotron resonance plasma source for Si(001)2 × 1 surface nitridation by N2: an X-ray photoemission study

Abstract

An ultra-high vacuum compatible electron cyclotron resonance (ECR) plasma source is employed for the first time in studying the surface nitridation of Si(001)2 × 1 surfaces held at low substrate temperature (Ts) with N2. The exposure to the efficiently activated and dissociated nitrogen flux in the microwave plasma is not limited to the silicon surface but results in the formation of ultra-thin dielectric near-stoichiometric Si3N4 layers (∼ 20 Å) analyzed in situ by X-ray photoelectron spectroscopy (XPS). These films, without hydrogen content and silicon deposit, could easily be grown in a few minutes at room temperature and at relatively low working pressures (∼ 10−4 mbar in the chamber). Comparatively, in order to reach similar thicknesses by conventional thermal nitridation with a more easily dissociable molecule than N2, i.e. NH3, very much higher Ts (700°C) and exposures (> 106 L) are needed. Therefore a considerable benefit in the growth kinetics is achieved at lower Ts in using the ECR source without destroying the underlying Si substrate as checked by X-ray photoelectron diffraction (XPD).