Highly Scalable and Robust Mesa‐Island‐Structure Metal‐Oxide Thin‐Film Transistors and Integrated Circuits Enabled by Stress‐Diffusive Manipulation

The increasing interest in flexible and wearable electronics has demanded a dramatic improvement of mechanical robustness in electronic devices along with high‐resolution implemented architectures. In this study, a site‐specific stress‐diffusive manipulation is demonstrated to fulfill highly robust and ultraflexible amorphous indium–gallium–zinc oxide (a‐IGZO) thin‐film transistors (TFTs) and integrated circuits. The photochemically activated combustion sol–gel a‐IGZO TFTs on a mesa‐structured polyimide show an average saturation mobility of 6.06 cm2 V−1 s−1 and a threshold voltage of −0.99 V with less than 9% variation, followed by 10 000 bending cycles with a radius of 125 μm. More importantly, the site‐specific monolithic formation of mesa pillar‐structured devices can provide fully integrated logic circuits such as seven‐stage ring‐oscillators, meeting the industrially needed device density and scalability. To exploit the underlying stress‐diffusive mechanism, a physical model is provided by using a variety of chemical, structural, and electrical characterizations along with multidomain finite‐element analysis simulation. The physical models reveal that a highly scalable and robust device can be achieved via the site‐specific mesa architecture, by enabling generation of multineutral layers and fine‐tuning the accumulated stresses on specific element of devices with their diffusion out into the boundary of the mesa regions. Highly flexible and robust low‐temperature solution‐processed amorphous indium–gallium–zinc–oxide thin‐film transistors and their integrated seven‐stage ring oscillators are realized by using a stress‐diffusive mesa‐structured substrate. The site‐specific mesa structures can accumulate bending stresses on specific regions of the devices with multineutral layers. To exploit the mechanism, chemical, structural, finite‐element analysis, and electrical investigations are carried out.