Island-Shaped Electrode for LCD Contact Reliability
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Solution Overview
Problem
In liquid crystal display devices of the FFS mode, the formation of reverse-tapered contact holes during the manufacturing process hinders reliable electrical connection between the upper and drain electrodes, leading to aperture ratio loss and increased parasitic capacitance between scanning lines and lower electrodes.
Innovation Solution
The formation of an island-shaped electrode on the drain electrode, separate from the lower electrode, with a contact hole in the inter-electrode insulating film allows for the upper electrode to be connected to the drain electrode via the island-shaped electrode, preventing reverse-tapered shape issues and ensuring reliable electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are formed during the manufacturing process, then electrical connection between electrodes is achieved, but reverse-tapered shape of contact holes hinders reliable connection and causes aperture ratio loss
Solution Approach 1:
The patent divides the electrode structure into multiple segments: a lower electrode, an island-shaped electrode, and an upper electrode. The contact hole is formed specifically to connect the upper electrode to the island-shaped electrode, which is separate from the lower electrode. This segmentation allows the contact hole to be precisely formed and connected without being affected by the reverse-tapered shape issue, thereby ensuring reliable electrical connection while preventing aperture ratio loss.
2Reliability
If contact holes are formed during the manufacturing process, then electrical connection between electrodes is achieved, but reverse-tapered shape increases parasitic capacitance between scanning lines and lower electrodes
Solution Approach 1:
By segmenting the electrode structure and forming the contact hole to connect the upper electrode to the island-shaped electrode (separate from the lower electrode), the patent isolates the contact hole formation process from the lower electrode. This prevents the reverse-tapered shape of the contact hole from increasing parasitic capacitance between scanning lines and the lower electrode, while still achieving reliable electrical connection.
Solution Approach 2:
The island-shaped electrode acts as an intermediary between the upper electrode and the lower electrode. The contact hole connects the upper electrode to this intermediate island-shaped electrode, which is positioned separately from the lower electrode. This intermediary structure enables electrical connection while preventing the harmful effect of reverse-tapered contact holes on parasitic capacitance.
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 enables reliable electrical connection between the upper and drain electrodes, preventing aperture ratio loss and reducing parasitic capacitance, thereby improving the performance and image quality of the liquid crystal display devices.
Implementation Method 1
A liquid crystal display apparatus displays an image by changing an orientation of liquid crystal molecules aligned in a predetermined direction by an electric field and controlling the amount of light transmission through a liquid crystal layer
Implementation Method 2
a contact hole that penetrates the interlayer resin film to reach a drain electrode of the TFT is formed on the interlayer resin film, and the pixel electrode and the drain electrode are electrically connected with each other via the contact hole
Data Source
AI summary
A liquid crystal display device is provided and includes first and second substrates; first wiring provided on first substrate along first direction; second wiring provided along second direction intersecting with first direction; thin-film transistor provided at intersection between first and second wirings; drain electrode electrically connected to thin-film transistor; organic insulating film formed on thin-film transistor and covering part of drain electrode; first opening that penetrates organic insulating film and exposing drain electrode; island-shaped electrode disposed on first opening and organic insulating film, and electrically connected to drain electrode; inorganic insulating film disposed on organic insulating film, the drain electrode, and the island-shaped electrode inside the first opening; a second opening that penetrates the inorganic insulating film and exposing the drain electrode; and a pixel electrode formed on the inorganic insulating film and electrically connected to the island-shaped electrode through the second opening.