The influence of dilution of the reactive gases in argon on electro-physical properties of ultra-thin silicon oxynitride layers formed by PECVD

The aim of this work was to check experimentally the effects of dilution of the reactive gases in argon on electro-physical properties of ultra-thin silicon oxynitride layers formed by PECVD. Possible changes in properties and composition of these layers were investigated by means of spectroscopic ellipsometry, electrical characterisation and XPS measurements. The results obtained have shown that argon dilution causes the formation of ultra-thin dielectrics with electro-physical properties to be inferior (e.g. higher leakage currents, higher mid-band interface traps density) to layers processed without dilution. In addition, the dilution of reactive gases in argon did not result in a decrease in the layer growth rate, which allows to improve either controllability (and thus repeatability of the process) or uniformity of the formed ultra-thin layers.