Silicon oxide gas barrier films deposited by reactive sputtering

Transparent silicon oxide thin films were deposited on polyethylene terephthalate substrates by means of reactive sputtering in oxygen and their gas barrier properties were evaluated. The SiOx film sputtered in 10% oxygen/90% argon mixture of inlet gases showed the lowest oxygen transmission rate, and this rate increased with an increase of inlet oxygen concentration. In addition, the oxygen contents of SiOx films increases rapidly within the range of small value of the inlet oxygen gas concentration (0–10%), and gently for oxygen gas concentration larger than 10%. The SiOx films sputtered at high oxygen concentration had more micro-defects than the films prepared at low oxygen concentration. The annealing at 120 °C in vacuum improved the gas barrier properties of the SiOx films sputtered at high oxygen concentration.