Effect of bipolar pulsed dc bias on the mechanical properties of silicon oxide thin film by plasma enhanced chemical vapor deposition

SiOx thin films synthesized on polycarbonate substrates by low temperature plasma processes are electronically meta-stable because the process temperature (<70 °C) needed to prevent deterioration of the polymer substrate is too low to allow the formation of a thermodynamically stable structure with stoichiometric electronic bonding. Therefore, the surfaces are very active and react chemically with the environment after scratching and pressure. This paper reports a coating method for producing dense structures with high hardness and good optical properties by controlling the ion current density (ion flux). The ion current density (ion flux) on the substrate was controlled by the RF power and additional bias with a bipolar pulsed dc frequency.

► SiOx films synthesized on PC substrates by PECVD at low temperature (< 70 °C). ► The higher energy affects the chemical structure and film properties. ► The ionized atoms arriving at the surface with higher energy contribute to the formation of chemical binding, resulting in an improvement in the SiOx structure and hardness (6.5 GPa).