Array Substrate Contact-Hole Insulation Against Pixel Electrode Shorts
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in preventing short-circuits between pixel electrodes and structural objects due to breakages in the electrode in-between insulating film, particularly when conductive objects overlap contact holes.
Innovation Solution
The array substrate design includes a thin film transistor with a drain electrode, multiple insulation films, and conductive portions, where the pixel electrode overlaps the drain electrode inside a contact hole and is connected to it, and additional insulation and conductive layers are strategically placed to prevent short-circuits by maintaining insulation even if the insulating film breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a structural object having electrically conductive properties is disposed to overlap the contact hole, then the pixel electrode can be electrically connected to the common electrode or other components, but if a breakage is caused in the electrode in-between insulating film, a short-circuit may be caused between the structural object and the pixel electrode
Solution Approach 1:
The patent introduces a planarization layer as an intermediary insulating structure between the pixel electrode and the conductive structural object (such as common electrode or black matrix). This planarization layer fills the contact hole and extends beyond it, providing a physical barrier that prevents direct contact between conductive elements even if the electrode in-between insulating film breaks. The planarization layer acts as a mediator that maintains electrical isolation while allowing the structural object to be disposed over the contact hole area.
Solution Approach 2:
The planarization layer is formed in advance before disposing the conductive structural object over the contact hole. By pre-forming this insulating barrier layer that extends beyond the contact hole, the patent ensures that when the structural object (common electrode or black matrix) is subsequently deposited, it automatically lands on the planarization layer rather than directly on the pixel electrode. This preliminary action prevents the short-circuit issue before it can occur.
2Reliability
If the common electrode includes openings in sections overlapping the contact holes, then short-circuit is less likely to be caused between pixel electrodes and common electrode, but a structural object requiring electrical conductivity cannot be disposed to overlap the contact hole
Solution Approach 1:
The patent makes the planarization layer a universal insulating structure that serves multiple functions simultaneously. It provides electrical insulation between the pixel electrode and any conductive structural object (whether common electrode, black matrix, or other components). The planarization layer's extended coverage over the contact hole area enables it to protect against short-circuits regardless of what conductive structural object is disposed above, thus providing adaptability to different device configurations without requiring modifications to the insulating structure.
3Reliability
If multiple insulation films and conductive portions are strategically placed, then short-circuits are prevented, but device complexity increases
Solution Approach 1:
The planarization layer is designed to perform multiple functions simultaneously: it provides electrical insulation between conductive layers, serves as a planarizing surface for subsequent deposition processes, and acts as a structural support layer. By making this single layer multi-functional, the patent reduces the need for additional separate insulating layers, thus preventing short-circuits without proportionally increasing device complexity.
Solution Approach 2:
The patent combines the insulation function with the planarization function into a single integrated layer structure. Rather than having separate insulating films and planarization layers, the planarization layer is formed to inherently provide both the insulating barrier against short-circuits and the planar surface needed for subsequent processing. This merging of functions reduces the total number of discrete layers while maintaining reliability.
Data Source
AI summary
An array substrate includes a thin film transistor including a drain electrode, a first insulation film included in an upper layer than the drain electrode and including a contact hole overlapping the drain electrode, a pixel electrode included in an upper layer than the first insulation film and overlaps the drain electrode at least inside the contact hole and is connected to the drain electrode, a second insulation film included in an upper layer than the pixel electrode and overlaps the pixel electrode inside the contact hole and extends outside the contact hole, a conductive portion included in an upper layer than the second insulation film and overlaps the pixel electrode at least inside the contact hole, and an insulation portion included in an upper layer than the pixel electrode and in a lower layer than the conductive portion and overlaps the pixel electrode inside the contact hole.