DEPOSITION OF SILICON DIOXIDE FILMS USING THE HELICON DIFFUSION REACTOR FOR INTEGRATED-OPTICS APPLICATIONS

Silicon dioxide thick films (1-18 mum) have been deposited at very rea sonable deposition rates (20-80 nm/min) with no intentional heating of the substrate (T approximately 200-degrees-C) using SiH4/O2 plasmas c oupled in a new type of plasma reactor: The radio frequency plasma exc itation used in the helicon diffusion reactor induces the formation of high-density plasmas (approximately 10(12) cm-3) with low plasma pote ntials. Three main parameters have been investigated; the total gas fl ow, the oxygen/silane gas flow ratio, and the magnetic confinement in the diffusion chamber. An in situ control of the refractive index and deposition rate has been obtained and correlated to an ex situ analysi s of the deposited films (infrared transmission spectroscopy and chemi cal etch rate measurements) and the effects of the deposition kinetics on the film properties such as the hydrogen content and the voids fra ction have been analyzed.