Low resistance transparent electrodes for large area flat display devices

Abstract

The dynamic performance of large area, high-resolution flat panel displays is contingent upon the conductivity of the transparent electrode. Electroplated copper and vacuum deposited aluminum bus bars attached to the sidewalls of conventional SnO2 electrodes offer theoretical improvements in conductivity while maintaining the electrode transmittivity. In association with a reactive ion etching process for delineating the tin oxide, auto registration methods for attaching copper by electroplating and aluminum by a resist lift off process are described, together with the achieved enhancement factors. A contact resistance between the aluminum and the tin oxide was found to significantly reduce the enhancement. The sidewall contact resistance lies between 0.4 and 4.0×104 Ω μm2, considerably lower than that previously reported for contacts to the tin oxide top surface. The enhancement factor for aluminum lies between two and three. The application of copper did not suffer from a contact resistance and an order of magnitude enhancement was obtained. We also report excellent adhesion, typically greater than 200 kg/cm2, of the metals to the tin oxide and identify the parametric space for achieving this.