Metal Oxide Thin Film Transistor for Flexible Displays
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Solution Overview
Problem
Existing thin film transistors with amorphous silicon or poly-silicon channel layers require high process temperatures, which can damage flexible substrates like plastic, making them unsuitable for flexible display devices.
Innovation Solution
A thin film transistor design that uses a metal oxide semiconductor layer as the channel layer, which can be formed without high temperature processes, and includes an organic gate dielectric layer and electrodes, allowing for flexible substrate compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous silicon or poly-silicon channel layer is used, then transistor performance is improved, but high process temperature is required which damages flexible substrates
Solution Approach 1:
The patent changes the material parameter of the channel layer from traditional amorphous silicon or poly-silicon to metal oxide semiconductor, which fundamentally alters the deposition temperature requirements from high temperature to low temperature processes, enabling compatibility with flexible substrates while maintaining transistor functionality
Solution Approach 2:
The patent employs an organic gate dielectric layer combined with metal oxide semiconductor channel layer, creating a composite material system that enables low temperature processing. The organic gate dielectric works synergistically with the metal oxide semiconductor to achieve proper transistor operation at temperatures compatible with flexible substrate manufacturing
2Reliability
If high process temperature is used for a-Si or p-Si TFT fabrication, then channel layer conductivity is improved, but flexible substrate deteriorates
Solution Approach 1:
The patent changes the material composition of the channel layer to metal oxide semiconductor, which fundamentally changes the thermal processing requirements. This material substitution allows achieving adequate channel layer conductivity through low temperature deposition processes, thereby eliminating the harmful thermal effects on flexible substrates
Solution Approach 2:
The patent replaces the traditional thermal activation mechanism used in silicon-based channel layers with a metal oxide semiconductor system that achieves conductivity through different physical mechanisms, allowing proper transistor operation without relying on high temperature processing that would damage the substrate
Data Source
AI summary
A thin film transistor suitable for being disposed on a substrate is provided. The thin film transistor includes a gate electrode, an organic gate dielectric layer, a metal oxide semiconductor layer, a source electrode and a drain electrode. The gate electrode is disposed on the substrate. The organic gate dielectric layer is disposed on the substrate to cover the gate electrode. The source electrode, the drain electrode and the metal oxide semiconductor layer are disposed above the organic gate dielectric layer, and the metal oxide semiconductor layer contacts with the source electrode and the drain electrode. Because the channel layer of the thin film transistor is a layer of metal oxide semiconductor formed at a lower temperature, thus the thin film transistor can be widely applied into various display applications such as flexible display devices.