Amorphous silicon thin-film transistor backplanes deposited at 200 °C on clear plastic for lamination to electrophoretic displays

The transition of thin-film transistor (TFT) backplanes from rigid plate glass to flexible substrates requires the development of a generic TFT backplane technology on a clear plastic substrate. To be sufficiently stable under bias stress, amorphous-silicon (a-Si:H) TFTs must be deposited at elevated temperatures, therefore the substrate must withstand high temperatures. We fabricated a-Si:H TFT backplanes on a clear plastic substrate at 200 °C. The measured stability of the TFTs under gate bias stress was superior to TFTs fabricated at 150 °C. The substrate was dimensionally stable within the measurement resolution of 1 μm, allowing for well-aligned 8 × 8 and 32 × 32 arrays of 500 μm × 500 μm pixels. The operation of the backplane is demonstrated with an electrophoretic display. This result is a step toward the drop-in replacement of glass substrates by plastic foil.