Display Device Gas Venting via Organic Insulator Opening
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Solution Overview
Problem
Transistors in liquid crystal display devices using oxide semiconductors face variations in electric characteristics due to impurities like hydrogen and moisture from organic insulating films, leading to deteriorated display quality and reliability.
Innovation Solution
A display device structure is implemented with a transistor, an organic insulating film, and a capacitor, where the entire surface of the organic insulating film is not covered by the capacitor, allowing released gases to escape, and a second inorganic insulating film is used to prevent impurities from entering the transistor, with a liquid crystal layer in contact with the organic insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the organic insulating film is completely covered by the capacitor components, then the capacitor provides full coverage and protection, but the released gas from the organic insulating film cannot escape and enters the transistor, causing characteristic variation
Solution Approach 1:
The patent extracts the harmful effect by creating an opening in the inorganic insulating film that allows the released gas to escape from the organic insulating film. This opening is formed in the region where the capacitor components are not present, enabling gas release without compromising the capacitor's protective function over the transistor.
Solution Approach 2:
The inorganic insulating film is segmented into covered regions (over the transistor for protection) and uncovered regions (over the organic insulating film for gas release). The capacitor components are positioned to cover only specific areas, leaving other areas exposed for gas escape pathways.
2Shape
If the organic insulating film is used to reduce unevenness, then surface flatness is improved, but impurities from the organic film enter the transistor and cause characteristic variation
Solution Approach 1:
The inorganic insulating film acts as an intermediary barrier between the organic insulating film and the transistor. It provides a protective layer that prevents impurities from the organic film from directly contacting and entering the transistor, while still allowing the organic film to fulfill its surface flatness function.
Solution Approach 2:
The harmful impurity release pathway is extracted by creating an opening in the inorganic insulating film that directs gas escape away from the transistor region, allowing the organic film to be used for surface flatness without compromising transistor reliability.
3Object-affected harmful factors
If the second inorganic insulating film covers the entire organic insulating film, then impurity blocking is maximized, but gas release is prevented and pressure builds up
Solution Approach 1:
The patent extracts the gas escape pathway by forming an opening in the second inorganic insulating film. This opening allows pressure-built gas to escape while the rest of the inorganic insulating film maintains its impurity blocking function.
Solution Approach 2:
The second inorganic insulating film is segmented into covered regions (for impurity blocking) and uncovered regions (for gas release). The opening is strategically positioned to allow gas escape without compromising the overall protective function.
Data Source
AI summary
To suppress a variation in characteristics of a transistor due to a released gas from an organic insulating film so that reliability of a display device is increased. The display device includes a transistor, an organic insulating film which is provided over the transistor in order to reduce unevenness due to the transistor, and a capacitor over the organic insulating film. An entire surface of the organic insulating film is not covered with components (a transparent conductive layer and an inorganic insulating film) of the capacitor, and a released gas from the organic insulating film can be released to the outside from exposed part of an upper surface of the organic insulating film.