Deposition of indium-tin-oxide films on polymer substrates for application in plastic-based flat panel displays

Indium-tin-oxide (ITO) films (1000 ± 100 Å) were deposited on glass and polymer (polyethersulfone) substrates by RF-magnetron sputtering for plastic-based flat-panel displays. A novel device and a stepped heating process were used both to eliminate the tensile force and to diminish the thermal expansion of the polymer substrates. Therefore, we succeeded in sputtering ITO films without any cracking or shrinkage of the polymer substrates. The oxygen partial pressure and post-deposition annealing conditions were varied to observe the dependence of the optical, electrical and etching properties of ITO films on the process parameters. The substrate material was polyethersulfone with a gas barrier layer. Moreover, in order to investigate the influences of the process parameters, X-ray diffractometer observations and measurement of transmission, sheet resistance and residual resistance after etching process were performed. We found that oxygen content in the polymer matrix resulted from the gas absorption of polymer substrates cause different dependence of polymer substrates on oxygen partial pressure compare with glass substrates. Consequently, we could obtain high conductive (20-25 Ω □^-1) and transparent (above 80%) ITO films deposited on polymer substrates using the condition of 0.2% oxygen partial pressure and vacuum annealing at the temperature of 180°C.