Deposition of "polysiloxane" thin films containing silver particles by an RF asymmetrical discharge

The aim of the present work is to produce silver-containing SiCxOyHz thin films by using simultaneous sputtering of silver and plasma polymerization in an HMDSO plasma. The ratio of plasma polymerization to sputtering was adjusted by using a pulsed flow rate of the hexamethyldisiloxane precursor, which permitted an accurate control of the co-deposition process. The presence of silver in the gas phase was detected by optical emission spectroscopy. The silver volume fraction was controlled over a wide range by superimposing physical sputtering onto the polymerization process taking place simultaneously within a very low and narrow range of HMDSO plasma pressure. The polymer matrix structures were analyzed by several techniques. FTIR spectra revealed the presence of Si-O-Si, Si-C-Si, SiCH3 and C=C groups whose amount varied with the silver content. TEM analysis showed Ag nanoparticles with sizes varying from 4 to 70 nm depending on the silver volume fraction.