Liquid Crystal Display Contact Hole Alignment
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Solution Overview
Problem
Conventional active matrix liquid crystal display devices face issues with uneven alignment of liquid crystal molecules due to thick interlayer films, leading to color phase irregularities and reduced image quality, particularly around contact holes where the interlayer is slanted.
Innovation Solution
A liquid crystal display device structure is implemented with a light-shielding layer covering or a colored layer being selectively removed over the contact holes to prevent uneven alignment, ensuring uniform liquid crystal layer thickness and eliminating color phase irregularities without increasing the number of processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an organic insulating film is used for planarization, then the film provides sufficient planarizing capability, but the contact hole becomes deep and causes uneven alignment of liquid crystal molecules
Solution Approach 1:
The insulating film is segmented into two distinct layers: a first insulating film (inorganic) and a second insulating film (organic). This segmentation allows each layer to perform its specialized function - the inorganic layer provides planarization while the organic layer provides flatness, thereby solving the problem of deep contact holes causing uneven alignment
Solution Approach 2:
The patent uses a composite structure combining inorganic and organic insulating materials. The inorganic insulating film (e.g., silicon oxide, silicon nitride) provides rigid planarization and structural stability, while the organic insulating film (e.g., acrylic resin) provides surface flatness and prevents liquid crystal infiltration, together resolving the contradiction between planarizing capability and alignment uniformity
2Stability of the object's composition
If the interlayer film thickness is increased for planarization, then planarizing capability is improved, but the liquid crystal layer thickness becomes uneven around contact holes
Solution Approach 1:
The thick interlayer film is segmented into two layers with different thicknesses and materials. The first insulating film has greater thickness for planarization, while the second insulating film is thinner and positioned at contact hole edges to maintain liquid crystal layer thickness uniformity
Solution Approach 2:
The second insulating film is selectively positioned at the edges of contact holes where the liquid crystal layer thickness is most critical. This local quality approach ensures that the planarizing capability is maintained while preventing uneven liquid crystal alignment specifically at the problematic contact hole regions
3Manufacturing precision
If a light-shielding layer is added to cover contact holes, then alignment uniformity is improved, but the number of processes increases
Solution Approach 1:
The second insulating film serves multiple functions: it provides surface flatness for uniform liquid crystal alignment, acts as a barrier to prevent liquid crystal infiltration into contact holes, and eliminates the need for a separate light-shielding layer. This multi-functionality improves alignment uniformity without increasing the number of processes
Solution Approach 2:
The patent extracts and eliminates the need for a separate light-shielding layer by integrating its functional requirements into the second insulating film. The organic insulating material provides the necessary optical and protective functions that would otherwise require an additional light-shielding layer, thereby simplifying the overall structure and process
Data Source
AI summary
To provide a liquid crystal display device having high visibility and high image quality by relieving color phase irregularity. A light-shielding layer is selectively provided so as to overlap with a contact hole for electrical connection to a source region or a drain region of a thin film transistor. Alternatively, by providing an opening portion of a colored layer (color filter) with an opening so as to overlap with a contact hole, uneven alignment of liquid crystal molecules does not influence display, and a liquid crystal display having high image quality can be provided.