Array Substrate Contact Hole Design for LCD Pixel Defect Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid crystal display panels, the undercutting of the drain electrode during the etching of the passivation layer leads to subsidence and separation, resulting in pixel defects due to the failure of the drain electrode to apply an electric field effectively.
Innovation Solution
The array substrate design includes a contact hole with a first exposing part to partially expose the drain electrode and a second exposing part to expose the transparent substrate adjacent to the drain electrode, either in a rectangular or U-shaped configuration, which prevents undercutting of the channel layer and ensures secure connection between the drain and pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passivation layer is etched to form a contact hole, then electrical connection between drain electrode and pixel electrode is achieved, but the channel layer is undercut causing drain electrode subsidence and separation
Solution Approach 1:
The drain electrode is formed to extend beyond the channel layer boundaries before the contact hole etching process. This preliminary extension ensures that when the passivation layer is etched, the drain electrode has sufficient lateral coverage to prevent undercutting of the channel layer and subsequent subsidence, while still achieving proper electrical connection through the contact hole.
Solution Approach 2:
The contact hole formation process is segmented into controlled etching steps that remove the passivation layer while preserving the channel layer. The drain electrode geometry is also segmented to extend beyond channel layer boundaries at specific regions, creating a protective overhang that prevents undercutting during etching while maintaining electrical connectivity.
2Manufacturing precision
If the contact hole is formed by overetching the passivation layer, then complete exposure of drain electrode is achieved, but the drain electrode separates from the pixel electrode
Solution Approach 1:
The drain electrode is preliminarily formed with extended lateral dimensions beyond the channel layer boundaries. This preliminary geometric configuration ensures that during contact hole etching, the drain electrode maintains structural integrity and prevents separation, even when the passivation layer is completely removed to achieve full exposure for electrical connection.
Data Source
AI summary
An array substrate includes a transparent substrate, a switching element, an insulating layer and a pixel electrode. The switching element includes a gate electrode formed on the transparent substrate and connected to a gate line, a channel layer formed on the gate electrode and extended in a first direction, a source electrode formed on the transparent substrate and connected to a source line and a drain electrode formed on the channel layer to cover the channel layer. The insulating layer has a contact hole to partially expose the drain electrode and the transparent substrate. The pixel electrode is connected to the drain electrode through the contact hole. When the above array substrate is employed in a liquid crystal display panel, the array substrate reduces pixel defect.