Techniques for Enhancing the Thermal Stability of Indium–Gallium–Zinc Oxide Thin-Film Transistors

The thermal stability of a metal-oxide thin-film transistor (TFT) can be improved by enclosing its channel region within an oxygen-rich local environment and preventing oxygen depletion from its channel region. Specific techniques for maintaining an oxygen-rich local environment include storing oxygen in an adjacent silicon oxide passivation layer, capping this passivation layer with a diffusion-barrier layer to prevent stored oxygen loss to the atmosphere, and incorporating an oxidation-resistant conducting liner beneath the source/drain electrodes to prevent oxygen consumption through electrode reactions. Additional improvements are achieved by maintaining a hydrogen-deficient local environment. These measures are applied to the design and construction of top-gate TFTs with sidewall spacers that act as barriers to the diffusion of both oxygen and hydrogen, thus enhancing the thermal stability of the transistors.