Distribution of ions and molecules density in N2/NH3/SiH4 inductively coupled plasma with pressure and gas mixture ratio)

A fluid model of 2D axis-symmetry based on inductively coupled plasma (ICP) reactor using N2/NH3/SiH4 gas mixture has been developed for hydrogenated silicon nitride (SiNx: H) deposition. The model was comprised of 62 species (electron, neutral, ions, and excitation species), 218 chemical reactions, and 45 surface reactions. The pressure (10∼40 mTorr) and gas mixture ratio (N2 80∼96 %, NH3 2∼10 %, SiH4 2∼10 %) were considered simulation variables and the input power fixed at 1000 W. Different distributions of electron, ions, and molecules density were observed with pressure. Although ionization rate of SiH2 + is higher than SiH3 + by electron direct reaction with SiH4, the number density of SiH3 + is higher than SiH2 + in over 30 mTorr. Also, number density of NH+ and NH4 + dramatically increased by pressure increase because these species are dominantly generated by gas phase reactions. The change of gas mixture ratio not affected electron density and temperature. With NH3 and SiH4 gases ratio increased, SiHx and NHx (except NH+ and NH4+) ions and molecules are linearly increased. Number density of amino-silane molecules (SiHx(NH2)y) were detected higher in conditions of high SiHx and NHx molecules density. © The Korean Institute of Electrical Engineers.