Thin Film Transistor With Surrounding Electrode To Minimize Cross-Talk
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Solution Overview
Problem
In thin film transistor (TFT) and flat panel display devices, cross-talk between adjacent TFTs due to leakage current occurs when the semiconductor layer is not patterned, and patterning organic semiconductor layers is difficult, leading to degraded electrical characteristics.
Innovation Solution
A TFT structure where one of the source or drain electrodes surrounds the other electrode in the same plane, preventing cross-talk without the need for patterning the semiconductor layer, and using organic semiconductor layers that are formed in the same plane for both electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the semiconductor layer is not patterned, then the manufacturing process is simpler, but cross-talk occurs between adjacent TFTs due to leakage current
Solution Approach 1:
The invention segments the gate electrode structure into multiple parts: a first gate electrode positioned over the channel region and a second gate electrode positioned over the source/drain regions. This segmentation allows the semiconductor layer to remain unpatterned while the segmented gate structure prevents cross-talk by creating electrical isolation between adjacent TFTs through the insulating layer that surrounds the channel region.
Solution Approach 2:
The invention introduces an insulating layer as an intermediary substance that fills the space between adjacent semiconductor layers and surrounds the channel region. This insulating layer acts as a mediator that prevents direct electrical contact between adjacent TFTs, thereby preventing cross-talk while allowing the semiconductor layer to remain continuous and unpatterned.
2Reliability
If the organic semiconductor layer is patterned, then cross-talk is prevented, but the electrical characteristics of the organic semiconductor layer are degraded
Solution Approach 1:
Instead of patterning the organic semiconductor layer, the invention segments the gate electrode into a first gate electrode and a second gate electrode. The first gate electrode controls the channel while the second gate electrode controls the source/drain regions. This segmentation achieves cross-talk prevention without requiring patterning of the organic semiconductor layer, thus preserving its electrical characteristics.
Solution Approach 2:
The insulating layer serves as an intermediary that prevents cross-talk between adjacent TFTs without requiring modification or patterning of the organic semiconductor layer. By placing the insulating layer in the space between adjacent semiconductor layers and surrounding the channel region, cross-talk is prevented while the organic semiconductor layer maintains its continuous structure and optimal electrical properties.
3Reliability
If the semiconductor layer is patterned to be separately used by each TFT, then cross-talk is prevented, but the manufacturing complexity increases significantly
Solution Approach 1:
The invention transfers the segmentation requirement from the semiconductor layer to the gate electrode structure. By dividing the gate electrode into a first gate electrode (over the channel) and a second gate electrode (over source/drain regions), the patent achieves cross-talk prevention without segmenting the semiconductor layer, thereby significantly reducing patterning complexity.
Solution Approach 2:
Instead of patterning the semiconductor layer to prevent cross-talk (conventional approach), the invention inverts the approach by keeping the semiconductor layer continuous and unpatterned, and instead patterning the gate electrode structure. This inversion of the conventional patterning target simplifies the manufacturing process while achieving the same cross-talk prevention goal.
Data Source
AI summary
In a thin film transistor and a flat panel display device having the same, cross-talk is minimized. The flat panel display device includes a substrate, a first thin film transistor, a second thin film transistor, and a display element. The first thin film transistor includes: a first gate electrode formed on the substrate; a first electrode insulated from the first gate electrode; a second electrode insulated from the first gate electrode and surrounding the first electrode in the same plane; and a first semiconductor layer insulated from the first gate electrode and contacting the first electrode and the second electrode. The second thin film transistor includes: a second gate electrode formed on the substrate and electrically connected to one of the first electrode and the second electrode; a third electrode insulated from the second gate electrode; a fourth electrode insulated from the second gate electrode and surrounding the third electrode in the same plane; and a second semiconductor layer insulated from the second gate electrode and contacting the third electrode and the fourth electrode.