Optical properties of plasma polymer films

Abstract The thickness and the refractive index of thin polymer films were measured in situ during plasma polymerization of hexamethyldisiloxane (HMDSO) by ellipsometry. The actual gas composition resulting from the plasma chemical conversion of organic vapour was analysed by mass spectrometry. The gas composition influences both the deposition process and the film properties. The optical dispersion and transmittance of the deposited films were characterized by spectroscopic ellipsometry (visible range) and spectrometry (UV-visible-IR range) respectively. It was found that especially the refractive index can be varied over a wide range depending on the plasma conditions, and that films with graded refractive index can be produced.