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

Abstract

A low‐temperature (300°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.

Flexible Oxide Thin Film Transistors, Memristors, and Their Integration

“…For instance, the Self‐Heating Effect (SHE) that resulted from bias stress ( V g = 40 V and V d = 20 V) was significantly higher on PI than on Si substrates, and it induced a negative V th shift from ≈0 V to −12 V. [ 103 ] Moreover, EMMO has been integrated in unipolar digital circuits (inverter, nor gates) on PI. [ 104 ] In unipolar design circuits with TFTs, the open‐loop gain is significantly lower than what a similar bipolar CMOS could exhibit; however, the proposed unipolar design could achieve comparable open‐loop gain with an increase in the design complexity. Also, the three inverter implementations proposed a hybrid‐TFT structure, made of both depletion and enhancement EMMO transistors, that provided ratio‐less design, high gain, and wide noise margin compared to pseudo‐CMOS designs.…”

50‐4: Invited Paper: Low‐Temperature Metal‐Oxide Thin‐Film Transistor Technology and the Realization of Electronic Systems on Flexible Substrates

“…Besides information displays, flexible electronics are being investigated for other applications including healthcare systems and human-machine interfaces (1). The capability of these systems would be limited without the inclusion of thin-film transistors (TFTs) as active devices.…”

43.4: Temperature Sensor Based on a Pseudo‐E Inverter Built with Metal‐Oxide Thin‐Film Transistors

“…Metal-oxide thin film transistors (TFTs) such as those based on indium-gallium-zinc oxide (IGZO) are widely used in the display panel as the switching devices because of their advantages of relatively high field-effect mobility (𝜇 FE ) and low leakage current. MO TFTs are also used to implement circuits such as basic logic gates (5), amplifiers (6), digital-to-analogue converters (7) gate driver (8), microprocessor (9), etc. Pseudo-CMOS design style (10) is a popular design method for the logic gate based on unipolar TFTs, which applies two stage structure to achieve full swing at the output voltage ( 𝑉 OUT ).…”