Growth of ITO thin films on polyimide substrate by bias sputtering

Transparent conducting indium tin oxide thin films were deposited on polyimide substrates by RF bias sputtering of ITO target. The influences of bias voltage on the structural and electrical properties of the films were investigated. In order to correlate the material characteristics with the plasma parameters during sputtering, we employed Langmuir probe and optical emission spectral studies. The films deposited onto positively biased substrates were poorly crystalline. An improvement in crystallinity was observed with increase in negative bias. The films deposited at a bias voltage of −20 V showed a preferred orientation in the [1 1 1] direction and has minimum resistivity compared to films grown at other biasing conditions. The measured plasma parameters were correlated to the film properties. The ITO films thus grown have been used as the channel layer for the fabrication of thin film transistor.