Forward Transfer of Thin-Film Devices to Flexible Substrates by Applying Thermal Stress

Abstract

We report the transfer of thin semiconductor films from a glass substrate to a plastic film using a germanium dioxide (GeO2) removing layer formed between the thin semiconductor films and the glass substrate. We applied thermal stress to achieve a rapid lateral etching of the GeO2 layer at several tens of mm/min by introducing an epoxy layer as an adhesive to attach the thin films to the plastic films. The GeO2 layer was dissolved up to a distance of 5 mm from the edge region of the 4-in.-diameter samples when the samples were kept in an 80–100 °C hot water bath for 90 min. The subsequent cooling of the sample at room temperature caused the complete etching of the GeO2 layer within 2 min. The rapid GeO2 dissolution resulting from the thermal stress induced by the epoxy layer bent the thin semiconductor layer and plastic films in the edge region and introduced water into the central region of the samples. Polycrystalline silicon thin-film transistors (poly-Si TFTs) were successfully transferred onto plastic films using the present method.