Temperature Dependent Variations of Properties of Polymer-Like Carbon Coatings Treated with High Energy Electrons

Polymer-like carbon coatings can be used for the protection of micro-electromechanical devices functioning in chemically or radiation harsh environment due to their beneficial properties. Properties of carbon coatings depend on the method of synthesis, initial gas mixture, admixture of additives, temperature and other technological parameters. Modification of carbon structures is possible applying high energy electrons. Coating mechanical properties become almost stable after their pretreatment with some doses of high energy electrons. Polymer-like carbon coatings were synthesized from acetylene gas plasma on n-type silicon substrates in the RF plasmotron system at temperatures in the range 293-673 K using plasma enhanced chemical vapor deposition method. Series of samples were prepared and irradiated with high energy (6 MeV) electrons in a medical linear accelerator. The ellipsometric method was used for estimation of some optical parameters and thickness of synthesized coatings. Structural changes of polymer-like carbon coatings were evaluated using the Raman spectroscopy and surface morphology was assessed by atomic force microscopy. Electron beam induced structural changes in the coatings were analyzed using the obtained results. The relations between the synthesis temperature and samples structure and surface morphology are discussed.