Single-step fabrication of double-layered metal thin film pattern for the electrodes of electronic devices

In many electronic devices, the electrode pattern consists of two different metal layers that improve the electrical and/or mechanical contact. We here report that double-layered metal thin film patterns can be fabricated at the micrometer scale by direct photoetching with a spatially-modulated neodymium-doped yttrium aluminum garnet pulsed laser beam. A zinc-tin oxide thin film transistor was fabricated using photoetched Ag/Al electrodes. An on/off ratio higher than 105 and an off-current less than 10−10 A were obtained, indicating that the channel area between electrodes was completely etched out. This article discusses the applicability and limitation of the direct photoetching process for double-layered metal films, along with the dependence of pattern fidelity on the film thickness.