Remote plasma-enhanced chemical vapour deposition of silicon nitride films: the effect of diluting nitrogen with helium

Abstract

SiN_xH_y films have been deposited using an SiH₄-N₂ mixture in a capacitively coupled remote plasma-enhanced chemical vapour deposition (RPECVD) system, where conditions favour transport of active species and energy to the deposition zone. In contrast to an inductively coupled RPECVD system, He dilution produces little influence on growth rate. Such a dilution does, however, strongly influence the film composition. Helium atoms promote the formation of atomic nitrogen in the gas phase and assist in delivering additional energy to the surface of the growing film; this leads to changes in the relative amounts of Si–H_i and N–H_j bonds and in the Si/N ratio of the deposited films. With the addition of helium, films of composition close to that of stoichiometric silicon nitride can be produced.