Series Oxide TFT Channel Layout for Degradation-Tolerant Displays
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Solution Overview
Problem
Oxide thin film transistors (TFTs) face instability during manufacturing, leading to local degradation of the oxide semiconductor pattern, resulting in defects like driving bright spots and sand mura in display panels due to shifted threshold voltage and increased off-state current.
Innovation Solution
The oxide TFT is designed with multiple oxide semiconductor patterns connected in series, allowing each sub-TFT to maintain functionality even if one deteriorates, ensuring the overall TFT remains operational with increased on-state current and controlled off-state current, thus preventing defects in display panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single oxide semiconductor pattern is used in the TFT, then the manufacturing process is simple, but the device is prone to local degradation and instability
Solution Approach 1:
The single oxide semiconductor pattern is divided into multiple oxide semiconductor patterns (first, second, third patterns) arranged in series between source and drain electrodes. This segmentation allows the TFT channel to be divided into multiple sub-channels, so that local degradation in one pattern does not completely disable the device. The series connection ensures that current must flow through all patterns, providing redundancy against local failures while maintaining manufacturing simplicity through concurrent formation of all patterns.
2Reliability
If multiple oxide semiconductor patterns are connected in series, then the stability and anti-degradation capability are improved, but the device complexity increases
Solution Approach 1:
Multiple oxide semiconductor patterns are formed concurrently in a single manufacturing process step using the same deposition and patterning procedures. The patterns are merged into a unified structure that functions as a single TFT channel, avoiding the need for separate fabrication processes for each pattern. This combining approach maintains manufacturing simplicity while achieving the reliability benefits of multiple patterns connected in series.
Data Source
AI summary
An oxide thin film transistor includes a gate electrode, and a first active layer structure and a second active layer structure arranged subsequently, the first active layer structure includes a first conductive connection portion and a second conductive connection portion arranged oppositely, the second active layer structure includes a third conductive connection portion and a fourth conductive connection portion arranged oppositely, and the second oxide semiconductor pattern respectively coupled to the third conductive connection portion and the fourth conductive connection portion, and an orthographic projection of the first oxide semiconductor pattern on the substrate and an orthographic projection of the second oxide semiconductor pattern on the substrate are both located within an orthographic projection of the gate electrode on the substrate, the second conductive connection portion is coupled to the third conductive connection portion.