Liquid Crystal Display Contact Hole Structure for Elution Prevention
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Solution Overview
Problem
In liquid crystal display devices where a color filter and active elements are placed on one substrate, there is a challenge in achieving positional alignment, leading to color mixtures and decreased numerical aperture, and the color filter is prone to elution into the liquid crystal layer due to chargeable impurities.
Innovation Solution
The design includes an active element substrate with a color filter and insulating layers, where the first contact portion of the second insulating layer is inside the second hole, and the second contact portion is inside both the first and second holes, preventing the color filter from eluting into the liquid crystal layer, with the thickness of the first insulating layer ranging from 0.33 to 2 times that of the color filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are formed to connect pixel electrodes through the color filter and insulating layers, then electrical connection is achieved, but the color filter becomes prone to elution into the liquid crystal layer due to thinned layer thickness at the contact hole vicinities
Solution Approach 1:
The patent implements a nested structure where the second insulating layer is positioned inside the contact hole, and the third contact portion protrudes inward of the first hole. This nested arrangement creates multiple protective barriers within the contact hole structure, preventing the color filter from eluting into the liquid crystal layer while maintaining electrical connectivity through the stacked insulating layers and contact portions.
Solution Approach 2:
The second insulating layer with its plate-like portion and protruded first contact portion acts as an intermediary barrier between the color filter and the liquid crystal layer. This intermediate structure prevents direct contact and potential elution of the color filter while still allowing electrical connection through the carefully designed contact portions that extend into the holes.
2Manufacturing precision
If a COA method is used to form color filter and active elements on one substrate, then positional alignment is improved, but manufacturing complexity increases due to the need for precise hole formation and multiple insulating layers
Solution Approach 1:
The patent divides the insulating structure into multiple segments: a first insulating layer, a second insulating layer with a plate-like portion, and a third insulating layer. Each segment serves specific functions - the first layer provides base insulation, the second layer with its protruded contact portion enables precise electrical connection, and the third layer provides additional protection. This segmentation allows for precise positional alignment while managing manufacturing complexity through functional division.
Solution Approach 2:
The patent utilizes the vertical dimension by creating a stacked multi-layer structure with holes extending through multiple layers. The contact portions protrude in the vertical direction into the holes, transforming a potentially complex planar alignment problem into a more manageable vertical stacking problem, where precision can be achieved through controlled deposition and etching processes.
Data Source
AI summary
Disclosed is a liquid crystal display device including an active element substrate having an active element; a first layer provided on the active element and having a first hole formed therein, the first layer being one of a first insulating layer and a color filter; a second layer provided on the first layer and having a second hole formed therein, the second layer being the other of the first insulating layer and the color filter; a common electrode provided on the second layer; a second insulating layer having a plate-like portion provided on the common electrode and a first contact portion protruded downward; and a pixel electrode having a second contact portion protruded downward. The first contact portion is provided inside the second hole, and the second contact portion is provided inside the first hole and inside the second hole and electrically connected to the active element.