Low‐temperature elevated‐metal metal‐oxide thin‐film transistors and circuit building blocks on a flexible substrate

A low-temperature (300 degrees C) thin-film transistor (TFT) technology based on the elevated-metal metal-oxide device architecture has been developed and deployed for realizing basic circuit building blocks on a polyimide (PI) flexible substrate. Both digital and analog circuit blocks have been simulated, fabricated, and characterized. Exhibiting insignificant impact on the performance of the TFTs, a 308-nm excimer laser was used to lift-off the PI from its glass-carrier substrate. Based on a multi-"threshold voltage" technology allowing both depletion- and enhancement-mode TFTs, alternative area-saving, ratio-less building blocks have been designed and simulated. The required tuning of the threshold voltage could be accomplished by selective fluorination, laser annealing, incorporation of multiple semiconducting metal oxides, or deployment of a dual-gate architecture.