Characterisation of SiOxCyHz thin films deposited by low-temperature PECVD

SiOxCyHz thin films were deposited from hexamethyldisiloxane (HMDSO)/O2 mixtures in a parallel plate, capacitively coupled, RF plasma reactor. Polyethylene terephthalate (PET), Si(1 0 0) wafers and KBr tablets were chosen as substrates. Effect of HMDSO/O2 ratio, total treatment pressure and power input on the properties of the deposited films were investigated. The structure and bondings were studied by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Wettability characteristics of the deposited thin films were investigated by means of water droplet contact angle measurements. Surface morphology was investigated with atomic force microscopy. Barrier properties of the SiOxCyHz thin films were investigated by measuring the water vapour transmission rate of the coated PET substrates. Correlations between the characteristics of the deposited film and their barrier properties were discussed.