An investigation has been made of the effect of dilution of nitrogen w
ith NF3 on the properties of silicon nitride deposited by remote plasm
a-enhanced CVD (PECVD). For NF3/N-2 mixtures with < 1.5 % NF3, fluorin
ated films with the structure of silicon nitride are formed but the to
tal concentration of bonded hydrogen in the films decreases with incre
asing NF3 flow rate, which leads to an improvement of the electrical p
roperties of the films compared with unfluorinated films. Such films c
ould be of interest for device applications. For NF3/N-2 mixtures with
NF3 > 1.5 %, films with the structure of silicon dioxide are formed,
but they do not contain enough oxygen to give typical SiO2 IR spectra.
It is suggested that the silicon dioxide structure arises because of
isoelectronic substitution of oxygen by NF.