FFS-LCD Fabrication Preventing Copper Compound Formation on Drain Electrodes
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Solution Overview
Problem
The existing methods for fabricating fringe field switching (FFS)-liquid crystal display (LCD) devices face challenges in achieving stable connections between copper data wires and indium tin oxide (ITO) pixel electrodes, leading to inferior connections and erosion issues during the manufacturing process, which affect the device's performance and viewing angle.
Innovation Solution
A method is developed to fabricate FFS-LCD devices by forming a gate electrode and gate line on a substrate, followed by a gate insulation film, active layer, source and drain electrodes, and a pixel electrode using a reduced number of mask processes, with a back channel etching step after pixel electrode patterning to prevent copper compound formation and ensure direct contact between copper and ITO, thereby stabilizing the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reduced number of mask processes is used to fabricate FFS-LCD devices, then productivity is improved, but the connection stability between copper data wires and ITO pixel electrodes deteriorates due to copper compound formation
Solution Approach 1:
The patent applies preliminary action by performing the pixel electrode patterning process before the back channel etching. This sequence ensures that the ITO pixel electrode is formed and protected before the copper etching occurs, preventing copper compounds from forming on the ITO surface and ensuring stable connections while maintaining the reduced mask process count for high productivity
Solution Approach 2:
The patent uses an intermediary approach by introducing a specific etching sequence where the back channel etching is performed after pixel electrode formation. This intermediary step prevents direct contact between copper etching chemicals and the ITO pixel electrode, thereby maintaining connection stability while still using fewer mask processes
2Device complexity
If copper data wires are directly connected to ITO pixel electrodes with fewer mask processes, then manufacturing complexity is reduced, but copper compound formation occurs causing erosion and inferior connections
Solution Approach 1:
The patent performs the pixel electrode patterning as a preliminary action before the back channel etching step. This ensures that the ITO pixel electrode is already in place and protected when the copper etching occurs, preventing copper compound formation on the ITO surface and maintaining high connection quality with reduced process complexity
Solution Approach 2:
The patent converts the potentially harmful back channel etching step into a beneficial process by performing it after pixel electrode formation. Instead of the etching harming the ITO pixel electrode, the sequence ensures the ITO is protected while the etching cleans the copper data wire surface, actually improving connection quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the number of mask processes, prevents copper compound formation, and ensures stable contact between copper and ITO, enhancing the connection quality and reducing ITO erosion, resulting in improved performance and wider viewing angles for FFS-LCD devices.
Implementation Method 1
a back channel etching step after pixel electrode patterning to prevent copper compound formation
Implementation Method 2
allowing a fringe field formed between a pixel electrode and a common electrode to penetrate through a slit
Implementation Method 3
driving LC molecules disposed on a pixel region and a common electrode, by allowing a fringe field formed between a pixel electrode and a common electrode to penetrate through a slit
Data Source
AI summary
A method of fabricating a fringe field switching (FFS)-liquid crystal display (LCD) device may have the following advantage. An inferior connection between the drain electrode and the pixel electrode may be prevented by preventing formation of a copper compound on the drain electrode, by performing a back channel etching after patterning a pixel electrode, and by performing a wet strip rather than a dry strip. This may result in a direct contact between copper and ITO, thereby reducing the number of mask processes.