Stepped Gate Electrode TFT Layout for Threshold Voltage Stability
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Solution Overview
Problem
The fabrication of display panels using large-sized mother substrates often results in performance deviations and reliability issues in thin film transistors due to process deviations across different areas of the substrate.
Innovation Solution
A thin film transistor design featuring a gate electrode with a thickness step profile, comprising a first part with a larger thickness and a second part with a smaller thickness, where the second part has higher light transmittance than the first part, is implemented to minimize performance deviations and ensure reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gate electrode with uniform thickness is used, then the manufacturing process is simple, but performance deviation occurs across different areas of large-sized mother substrates
Solution Approach 1:
The gate electrode is designed with different thicknesses in different regions: a first thickness in a first area and a second thickness in a second area. This local quality variation compensates for process deviations that occur across large-sized mother substrates, improving performance consistency without significantly complicating the manufacturing process.
2Reliability
If a thicker gate electrode is used, then the electrical performance is improved, but light transmittance is reduced
Solution Approach 1:
The gate electrode employs different thicknesses in different areas to balance electrical performance and light transmittance. The first area has a thicker gate electrode for better electrical stability, while the second area has a thinner gate electrode for higher light transmittance, allowing both requirements to be satisfied simultaneously in different regions of the display device.
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 proposed thin film transistor design effectively reduces performance deviations and maintains reliability by resolving electron traps through light transmission, thereby stabilizing the threshold voltage and improving long-term reliability.
Implementation Method 1
a second part having a thickness smaller than a thickness of the first part, at least partially overlapping the channel portion, and wherein light transmittance of the second part is greater than light transmittance of the first part
Implementation Method 2
resolving electron traps through light transmission
Data Source
AI summary
A display device includes a substrate and multiple thin film transistors, each of which comprises an active layer having a channel portion, and a gate electrode that overlaps the channel portion of the active layer. The gate electrode includes a first part that at least partially overlaps the channel portion, and a second part having a thickness smaller than that of the first part, at least partially overlapping the channel portion, and light transmittance of the second part is greater than that of the first part.