LCD Electrode Fabrication via Printing and Mask Reduction
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Solution Overview
Problem
The existing fabrication methods for fringe field switching (FFS) mode liquid crystal displays (LCDs) require a large number of photomasks, leading to increased processing time and costs due to the complexity of the photolithography process.
Innovation Solution
The process is simplified by replacing photolithography with printing processes, reducing the number of masks needed, and using a combination of printing and photomasking steps to form the necessary electrode structures, thereby reducing the total number of photomasking processes from five to three.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form electrode structures, then manufacturing precision is improved, but device complexity and processing time increase
Solution Approach 1:
The patent combines multiple photomasking steps into fewer integrated steps. Specifically, the common electrode and pixel electrodes are formed in the same transparent conductive layer using a single photomasking process, and the insulating layer patterns are formed simultaneously with electrode patterns, reducing the total number of photomasking steps from five to three while maintaining manufacturing precision
Solution Approach 2:
The transparent conductive layer serves multiple functions: it forms both the common electrode and pixel electrodes, and also provides insulation between different electrode structures. This multi-functionality reduces the need for separate processing steps for each electrode type and layer, simplifying the overall fabrication process
2Manufacturing precision
If multiple photomasking steps are used, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
Multiple electrode formation steps are merged into single photomasking operations. The first photomasking step forms both the common electrode pattern and pixel electrode pattern simultaneously in the transparent conductive layer, and the second photomasking step forms both the insulating layer pattern and additional electrode structures, doubling the pattern formation efficiency
Solution Approach 2:
The insulating layer is formed and patterned in advance before final electrode assembly, allowing subsequent steps to proceed more quickly. The insulating layer patterns are created during the same photomasking step as the electrode patterns, eliminating the need for separate insulating layer formation and patterning steps that would otherwise occur earlier in the process
3Manufacturing precision
If five photomasking processes are used, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent merges five separate photomasking processes into three integrated photomasking steps. The first step forms the common electrode and pixel electrode patterns, the second step forms the insulating layer and additional electrode structures, and the third step completes the pixel electrode formation, eliminating two full photomasking cycles and their associated drying and etching operations
Solution Approach 2:
The fabrication process maintains continuous useful action by forming multiple structures in each photomasking step without interrupting the production flow. Each photomasking step simultaneously creates multiple patterns and layers, ensuring that every processing step contributes to multiple features of the final device, maximizing productivity while maintaining precision
Data Source
AI summary
A method for fabricating an LCD includes: providing a substrate with a thin film transistor (TFT) part defined thereon; forming a metallic film for a gate electrode on the substrate; etching the metallic film through a first printing process to form a gate electrode; sequentially forming a gate insulating layer, a semiconductor layer, and a metallic film for source and drain electrodes on the substrate; selectively etching the metallic film for source and drain electrodes, the semiconductor layer and the gate insulating layer through a second printing process to form a gate insulating layer pattern, a preliminary active pattern and a metallic film pattern which are sequentially stacked such that the gate insulating layer pattern is over-etched from the side of the preliminary active pattern; forming an insulating layer on the substrate with the metallic film pattern; etching the insulating layer to expose the metallic film pattern; forming a transparent conductive film on the metallic film pattern and a remaining insulating film; and selectively etching the transparent conductive film, the metallic film pattern, the preliminary active pattern to form an active pattern, a source electrode, a drain electrode, and a pixel electrode connected with the drain electrode.