Ultraviolet curing imprint lithography on flexible indium tin oxide substrates

In this study, an imprint lithography technique was performed to transfer patterns onto indium tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) substrates by embossing an etch barrier on the substrates and curing them under irradiation at room temperature. The etch barriers containing glycidyl methacrylate were spectrally analyzed to verify that they were deposited on the ITO-PET substrates firmly and rapidly with minimum variation in dimensions. To fabricate the ITO patterns, the substrate was etched by reactive-ion etching to eradicate the residual layers and by wet etching to carve the undisplaced ITO lines. Scanning electron microscopy observation and profilometric analysis for these processes showed only about 2% of linewidth shrinkage after polymer cross linking, easily compensated in mask design in applications. Also, the 150 nm of ruled features on the pattern were successfully transferred using the same resist. Moreover, the flexible ITO patterns illuminated the practical electroluminescence device, verifying that UV-curing imprint lithography is feasible for patterning ITO-PET surfaces.