Diagnostics and insights on PECVD for gas-barrier coatings

In this work, we report on our last results concerning the polyethyleneterephtalate barrier performance optimization as a function of the chemistry of the SiOx coating, deposited by means of hexamethyldisiloxane/oxygen-fed plasmas ignited in an RF capacitively coupled parallel plates reactor. The influence of the gas feed composition and power on the plasma phase/coating chemistry and on the O-2 gas transmission rate has been investigated. The plasma phase has been studied by means of Fourier transform infrared absorption (FT-IR) and optical emission spectroscopies (OES), and the results have been coupled to the film chemistry investigated by means of FT-IR spectroscopy. These techniques show excellent potentialities in the correlation of the plasma phase and film chemistries with the barrier properties of the SiOx-coated polymer, especially when a very good barrier level is required.