Liquid Crystal Array Substrate Stepped Contact Hole
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Solution Overview
Problem
In liquid crystal displays, the large depth of contact holes prevents the alignment film from spreading, leading to defective application and deteriorated display quality due to the inability of inkjet devices to evenly distribute ink within these holes.
Innovation Solution
A stepped level difference is formed on the organic insulating film within the contact holes to facilitate the spreading of the alignment film, reducing the surface area of the contact holes and ensuring complete coverage by the alignment film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large depth contact hole is formed to connect the thin film transistor and pixel electrode, then electrical connection is achieved, but the alignment film cannot spread into the contact hole
Solution Approach 1:
The contact hole is segmented into multiple depth levels by forming stepped structures on the organic insulating film. This segmentation allows the alignment film to be deposited in stages, with each step providing a platform for the inkjet device to deposit alignment material that can then spread to the next lower level, ultimately achieving complete coverage of the deep contact hole.
Solution Approach 2:
The solution transitions from a single-depth contact hole structure to a multi-level stepped structure, adding vertical dimensionality. By creating multiple terraces at different heights, the alignment film can spread horizontally across each step before moving to the next level, effectively solving the spreading problem in deep holes.
2Extent of automation
If an inkjet device is used to form the alignment layer, then automated alignment film application is achieved, but the ink is not widely spread to fill the contact hole
Solution Approach 1:
The stepped structures are formed on the organic insulating film before the alignment film is applied. This preliminary action creates predetermined platforms that guide and facilitate the spreading of the alignment ink, ensuring that the automated inkjet process can effectively deposit material that will then spread to cover the entire contact hole area.
Solution Approach 2:
The stepped structures on the organic insulating film act as intermediaries between the inkjet device and the deep contact hole. These steps serve as intermediate platforms that receive the alignment ink and facilitate its gradual spreading downward into the contact hole, bridging the gap between the deposition method and the deep substrate feature.
3Device complexity
If the alignment film is not spread into the contact hole, then the manufacturing process is simplified, but dark fringes are generated around the contact hole
Solution Approach 1:
The stepped structures are localized specifically on the organic insulating film within and around the contact hole regions. This local modification provides the necessary platforms for alignment film spreading only where needed, without requiring complex changes to the entire device structure. The local quality enhancement at the contact hole interface prevents dark fringe generation.
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
An array substrate for a liquid crystal display and a method for manufacturing the same are disclosed. The array substrate for a liquid crystal display includes a source electrode (117) and a drain electrode (119) and an organic insulating film (125) positioned on the source electrode (117) and the drain electrode (119). The organic insulating layer (125) includes a first contact hole (CH1) exposing the drain electrode (119), and having a stepped level difference formed on the sloping surface of the first contact hole (CH1).