ION CONTRIBUTION TO THE DEPOSITION OF SILICON DIOXIDE IN OXYGEN SILANE HELICON DIFFUSION PLASMAS/

A very high silane dissociation rate (greater than or equal to 95%) ha s been measured using mass spectrometric analysis of neutral species i n a low pressure (a few mTorr) high density (greater than or equal to 10(11) cm(-3) for a radio frequency source power of 800 W) oxygen/sila ne (O-2/SiH4) helicon deposition reactor. Energy selective mass spectr ometric measurements of positive ions have been performed for O-2/SiH4 flow rate ratios varying from 1 to 10 and for a constant power of 800 W. A simple model of the ion-induced deposition rate has been develop ed and the results have been compared to the measured deposition rate. It appears that 20%-50% of the silicon atoms in the near-stoichiometr ic deposited oxides could result from the flux of silicon-containing i ons (essentially Si+ and SiOH+) to the substrate during deposition. An oxidation process via O-2(+) ions and an etching process via H-3(+) i ons could possibly be involved in the ion-induced deposition mechanism . (C) 1997 American Institute of Physics.