Active Matrix Substrate Storage Capacitor Defect Repair
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Solution Overview
Problem
Active matrix substrates for liquid crystal display devices face issues with point defects such as short circuits between storage capacitor elements, leading to reduced display quality and increased production costs due to defects like conductive foreign particles and poor etching or photolithography, which affect the aperture ratio and overall image quality.
Innovation Solution
The solution involves forming two or more upper storage capacitor electrodes opposed to a storage capacitor line, with contact holes in the interlayer insulating film connecting them to the pixel electrode, allowing for electrical continuity and enabling repair of point defects by isolating shorted electrodes using laser techniques, thereby maintaining normal operational levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If a single upper storage capacitor electrode is used, then the structure is simple, but point defects such as short circuits cannot be repaired
Solution Approach 1:
The upper storage capacitor electrode is divided into multiple separate electrodes (first, second, and third upper storage capacitor electrodes). This segmentation allows individual electrodes to be isolated and repaired if a short circuit occurs, enabling defect repair while maintaining overall functionality of the storage capacitor element.
2Illumination intensity
If the aperture ratio is increased, then display quality improves, but the area for storage capacitor elements is reduced
Solution Approach 1:
The storage capacitor element utilizes the vertical dimension by forming upper storage capacitor electrodes that extend in the vertical direction above the storage capacitor line. This three-dimensional arrangement increases the effective capacitance area without occupying additional planar space, thereby preserving aperture ratio while ensuring sufficient storage capacitor area.
3Manufacturing precision
If conventional fabrication processes are used, then manufacturing is straightforward, but conductive foreign particles and poor etching affect quality
Solution Approach 1:
The storage capacitor element employs different material layers with distinct properties: a low-resistance semiconductor layer for electrical connection and a high-resistance semiconductor layer for insulation. This local differentiation of material properties enhances manufacturing precision by providing built-in electrical isolation that prevents short circuits caused by conductive foreign particles or etching defects.
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
This approach effectively repairs point defects, improves production yields, and maintains the aperture ratio, ensuring high display quality by ensuring electrical continuity between the pixel electrode and storage capacitor line, reducing the visibility of defects.
Implementation Method 1
isolating shorted electrodes using laser techniques
Data Source
AI summary
An active matrix substrate includes a substrate, a TFT formed on the substrate, a storage capacitor element formed on the substrate, an interlayer insulating film covering the storage capacitor element, and a pixel electrode formed on the interlayer insulating film. The storage capacitor element includes a storage capacitor line, an insulating film formed on the storage capacitor line, and two or more storage capacitor electrodes opposed to the storage capacitor line with the insulating film interposed therebetween. The two or more storage capacitor electrodes are electrically connected via associated contact holes formed in the interlayer insulating film to the pixel electrode and electrically continuous with a drain electrode of the TFT.