FFS Liquid Crystal Display Planarization Layer Contact Hole Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Horizontal electric field type liquid crystal display devices, particularly those in FFS mode, face challenges with productivity due to increased manufacturing processes and low aperture ratio caused by multilevel formations over TFT elements and common electrode lines, leading to reduced transmittivity and aperture ratio.
Innovation Solution
A liquid crystal display device structure featuring a planarization layer with first and second electrodes of transparent conductive material, disposed opposing each other with a second insulator in between, and a connection-switching line formed on the surface of the second insulator, reducing the need for photolithographic and etching processes and eliminating multilevel formations, thus enhancing productivity and aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a planarization layer is formed over TFT elements and common electrode lines to eliminate multilevel formations, then manufacturing precision and aperture ratio are improved, but the number of manufacturing processes increases and productivity decreases
Solution Approach 1:
The patent combines the planarization layer formation with the common electrode line formation by disposing the common electrode line on the planarization layer surface. This integration eliminates the need for separate planarization processes while maintaining the aperture ratio benefits, thereby improving productivity without sacrificing manufacturing precision.
Solution Approach 2:
The patent resolves the multilevel formation issue by transitioning from a planar structure to a three-dimensional structure where the common electrode line is positioned on the planarization layer surface rather than within the same plane. This dimensional change eliminates the need for additional photolithographic and etching processes, improving both manufacturing precision and productivity.
2Manufacturing precision
If photolithographic and etching processes are used to form contact holes in the planarization layer, then manufacturing precision is improved, but the width of contact hole mouths increases and aperture ratio decreases
Solution Approach 1:
The patent performs preliminary planarization by forming the planarization layer before creating contact holes. This preliminary action provides a flat surface that facilitates precise contact hole formation with smaller mouth widths, thereby maintaining both manufacturing precision and maximizing aperture ratio by minimizing the area occupied by contact holes.
Data Source
AI summary
A manufacturing method for a horizontal electric field type liquid crystal display device of fringe field switching (FFS) or the like mode whereby pixel electrodes and a common electrode are disposed opposing each other on a planarization layer with an insulator interposed, includes a step whereby a planarization layer 18 is formed that has openings formed therein at the positions where contact holes 21a are to be formed in the surface of a passivation layer 17, and the portions of such planarization layer at the periphery of the display area are removed, followed by a step whereby the exposed portions of the passivation layer 17 are removed using a fluorine etching gas. By employing such method, the size of the contact hole 21a mouths can be rendered smaller, and also the number of manufacturing processes can be reduced, compared to the related art.