Thin Film Transistor Shielding Pattern for Light Leakage
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Solution Overview
Problem
Thin film transistors with oxide active layers exhibit unstable characteristics due to light-induced leakage currents, affecting their electrical reliability, especially in large-area devices and OLED displays, where high process temperatures and uniformity issues are challenging.
Innovation Solution
A thin film transistor array substrate with a shielding pattern applied a constant voltage through shielding lines, positioned under the transistors, and undergoes a thermal process to dehydrate hydrogen and hydroxide ions from the active layer, improving reliability and characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide active layer is used in thin film transistors, then mobility and ease of manufacture at low temperature are improved, but light-induced leakage current increases causing unstable characteristics
Solution Approach 1:
A shielding pattern is introduced as an intermediary element between the oxide active layer and external light sources. This pattern blocks or filters light from reaching the active layer, preventing photo-induced leakage current while allowing the low-temperature manufacturing advantages of oxide semiconductors to be retained.
Solution Approach 2:
The shielding pattern is positioned and configured in advance to prevent light from reaching the oxide active layer before light-induced leakage can occur. This preliminary protective action eliminates the harmful effect of light exposure while maintaining the inherent benefits of oxide semiconductor technology.
2Reliability
If polycrystalline silicon is used for the active layer, then electrical reliability is improved, but high process temperature and manufacturing complexity increase
Solution Approach 1:
The invention changes the material parameter from polycrystalline silicon to oxide semiconductor, which allows operation at lower temperatures. The shielding pattern is then introduced to compensate for the reduced electrical reliability of oxide semiconductors by blocking light-induced leakage, effectively decoupling the temperature parameter from the reliability constraint.
3Speed
If oxide is used in the active layer, then mobility is improved, but light-induced leakage current reduces reliability
Solution Approach 1:
The shielding pattern serves as a mediator that protects the high-mobility oxide active layer from light exposure. This allows the oxide material's superior mobility characteristics to be utilized while the shielding pattern compensates for the material's susceptibility to light-induced leakage current.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the reliability and initial characteristic dispersion of thin film transistors by applying a constant voltage to the shielding pattern and performing a thermal dehydration process, thereby stabilizing the active layer and improving the overall performance of the transistors.
Implementation Method 1
performing a thermal process to dehydrate hydrogen and hydroxide ions from the active layer
Data Source
AI summary
A thin film transistor array substrate and a method for manufacturing the same are disclosed. The thin film transistor array substrate includes a plurality of pixel units defined by a cross structure of gate lines with data lines and power lines on a substrate. Each of the pixel units includes a driving unit, which includes a switching thin film transistor and a driving thin film transistor receiving a signal from the gate line, the data line, and the power line, and a capacitor storing a signal; and a light emitting unit emitting light on a pixel electrode receiving a driving current from the driving thin film transistor. Each of a plurality of shielding patterns is positioned under the switching thin film transistor and the driving thin film transistor of the pixel unit.