Display Electrode Contact Hole Layout for Higher Pixel Density
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Solution Overview
Problem
The existing display devices face a challenge in maintaining pixel density due to the larger area of contact holes penetrating through stacked insulating layers, which degrades the pixels per inch (PPI) performance.
Innovation Solution
The proposed solution involves a display device design where a contact hole penetrates a plurality of insulating layers to electrically connect two electrodes, with a reduced area of the contact hole by using a specific structure of the thin film transistor and over-coat layers, allowing for efficient stacking of signal lines and electrodes without decreasing pixel density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are used to penetrate stacked insulating layers for electrical connection, then electrical connectivity between electrodes is achieved, but the area of contact holes increases which degrades pixel density
Solution Approach 1:
The contact hole structure is segmented into multiple sections: an upper contact hole portion, a lower contact hole portion, and an intermediate connection portion. This segmentation allows each portion to be optimized independently - the upper portion can be smaller for high pixel density while the lower portion provides sufficient area for electrical connection, resolving the contradiction between connectivity and area occupation
Solution Approach 2:
The contact hole is nested within the insulating layers structure, with the upper contact hole portion positioned within the upper insulating layer and the lower contact hole portion positioned within the lower insulating layer. This nesting approach allows the contact hole to efficiently utilize the vertical space between layers, reducing the horizontal area occupation while maintaining electrical connectivity
2Device complexity
If signal lines and thin film transistors are stacked to improve integration, then device integration is enhanced, but the area occupied by contact holes increases which reduces pixels per inch
Solution Approach 1:
The contact hole structure transitions from a conventional single-plane opening to a multi-dimensional structure with distinct upper and lower portions connected through an intermediate section. This dimensional transformation allows the contact hole to maintain electrical connectivity while occupying less area in the pixel plane, enabling better integration without sacrificing PPI
3Area of stationary object
If contact hole area is reduced to improve pixel density, then pixels per inch increases, but electrical connectivity between stacked electrodes may be compromised
Solution Approach 1:
Different portions of the contact hole structure are assigned different qualities and dimensions: the upper contact hole portion has a smaller area optimized for pixel density, while the lower contact hole portion has a larger area optimized for electrical connectivity. This local quality differentiation resolves the contradiction by allowing each region to fulfill its specific function
Data Source
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AI summary
Provided are a display device and a method of manufacturing the same. A display device includes: a lower substrate (100), a first over-coat layer (130) on the lower substrate (100), the first over-coat layer (130) including a first contact hole (130h), a thin film transistor (200) between the lower substrate (100) and the first over-coat layer (130), the thin film transistor (200) including a drain electrode (260) including an end portion overlapping the first contact hole (130h), the end portion of the drain electrode (260) including an under-cut region (UC), a lower passivation layer (120) between the thin film transistor (200) and the first over-coat layer (130), the lower passivation layer (120) partially exposing a side surface of the end portion of the drain electrode (260), and a light-emitting structure (500) on the first over-coat layer (130), the light-emitting structure (500) being electrically connected to the thin film transistor (200) through the first contact hole (130h).