TFT Substrate Segmented Gate Electrode Aperture Ratio
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Solution Overview
Problem
Conventional lithography technology limits the reduction of TFT size, leading to a decrease in pixel aperture ratio due to the fixed distance between the source and drain electrodes, hindering the advancement of LCD resolution.
Innovation Solution
The design of a thin film transistor substrate with a specific layered structure, including a gate electrode, active layer, etch stop layer, source electrode, inorganic and organic insulation layers, and a transparent electrode, with strategically formed openings and barrier layers to reduce the active layer width and minimize byproduct deposition, enhancing electrical properties and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional lithography technology is used, then the manufacturing process is simple, but the TFT size cannot be reduced due to limited resolution
Solution Approach 1:
The patent divides the gate electrode into multiple segments (first gate electrode and second gate electrode) separated by a gate insulation layer. This segmentation allows the source and drain electrodes to be positioned closer together, effectively reducing the TFT size while maintaining manufacturing feasibility with conventional lithography processes.
Solution Approach 2:
The patent introduces a vertical dimension by stacking multiple layers (gate electrode, gate insulation layer, active layer, source electrode, drain electrode) to achieve size reduction. By utilizing the Z-axis (vertical stacking) rather than only the X-Y plane, the TFT footprint is reduced while maintaining electrical functionality.
2Measurement precision
If pixel size is reduced to increase resolution, then the LCD resolution is improved, but the aperture ratio of the pixel is greatly decreased
Solution Approach 1:
By segmenting the gate electrode structure and optimizing the layout of source and drain electrodes, the patent reduces the non-active area within the pixel. This allows a larger proportion of the pixel area to be dedicated to the active layer, thereby improving the aperture ratio while maintaining high resolution.
Solution Approach 2:
The patent optimizes critical dimensions such as the width of the active layer, the spacing between source and drain electrodes, and the thickness of insulation layers. These parameter changes enable smaller pixel sizes with improved aperture ratios by precisely controlling the dimensional relationships between different structural elements.
3Length of moving object
If the distance between source electrode and drain electrode is reduced, then the TFT size is reduced, but byproduct deposition increases and electrical properties deteriorate
Solution Approach 1:
The patent introduces an etch stop layer and barrier layer as intermediary structures between the source/drain electrodes and the active layer. These intermediary layers prevent harmful byproduct deposition from reaching the active layer while allowing the source and drain electrodes to be positioned close together, thus maintaining electrical properties despite reduced spacing.
Solution Approach 2:
The etch stop layer and barrier layer are formed in advance before the source and drain electrodes are deposited. This preliminary action creates a protective structure that prevents byproduct contamination during subsequent manufacturing steps, enabling closer electrode spacing without compromising electrical performance.
Data Source
AI summary
Disclosed is a TFT substrate, including a substrate and a gate electrode thereon. A gate insulation layer over the substrate covers the gate electrode. An active layer is disposed over the gate insulation layer. An etch stop layer is disposed over the active layer and the gate insulation layer. A first opening penetrates the etch stop layer to expose a first part of the active layer. A source electrode over the etch stop layer is electrically connected to the first part of the active layer through the first opening. A first inorganic insulation layer is disposed over the source electrode and the etch stop layer. A second opening penetrates the first inorganic insulation layer and the etch stop layer to expose a second part of the active layer.