Properties of ITO films deposited on plastic substrate by RF superimposed DC magnetron sputtering method

Tin doped indium oxide (ITO) films were deposited on plastic films by RF superimposed DC magnetron sputtering method using an In2O3-10 wt.% SnO2 target without intentionally heating substrates. We have investigated the effects of an RF superimposed DC power system on the electrical, optical, and mechanical properties of the ITO films by using Four-Point Probe, Hall Effect Measurement, UV-Vis-NIR Spectrophotometer, XRD, and Residual Stress Measurement. With increasing the amount of RF power superimposed on DC power, the sputtering discharge voltages of DC power supply were decreased from -290 V to -100 V, i.e., plasma impedance decreased with an increase of the amount of RF power. The resistivity of the samples drastically decreases with increasing RF power, and shows the lowest value of 3.8x10(-4) Omega.cm. Hall effect measurements explain that the increase of carrier mobility is strongly related with the enhancement of the resistivity of ITO films even though there is no difference on its concentration. The RF power superimposed on DC power also reduces the residual stress of the samples up to the stress level of similar to 200 MPa at optimum values of RF power.