Lighting Test Transistor Layout for Static Protection
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Solution Overview
Problem
Display devices face issues with insulation breakdown phenomena in lighting test transistors due to static electricity during manufacturing, leading to shorts and deteriorated display quality.
Innovation Solution
Incorporating lighting test transistors with specific design features, including a gate insulating layer, interlayer insulating layer with strategically placed contact holes, and an antistatic circuit to prevent static electricity from causing insulation breakdown, ensuring a distance of 7 um or more between contact holes and gate electrodes, which lowers charge mobility and prevents shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lighting test transistors are formed in the display device, then lighting test can be performed to detect damage, but insulation breakdown phenomenon occurs due to static electricity during manufacturing
Solution Approach 1:
The patent applies preliminary action by increasing the distance between contact holes and gate electrodes before static electricity can cause insulation breakdown. The interlayer insulating layer is designed with contact holes positioned at a sufficient distance from gate electrodes, creating a preventive structure that mitigates the harmful effect of static electricity before it can damage the transistor during manufacturing processes.
2Area of stationary object
If contact holes are placed closer to gate electrodes, then device area is reduced, but insulation breakdown and shorts occur in lighting test transistors
Solution Approach 1:
The patent applies parameter changes by optimizing the distance parameter between contact holes and gate electrodes. Specifically, the interlayer insulating layer is designed with contact holes positioned at a controlled distance from gate electrodes, changing the spatial parameter to prevent insulation breakdown while managing the area occupation of the transistor structure.
3Ease of operation
If lighting test transistors are used to provide data voltage to pixels, then pixel operation is enabled, but display quality deteriorates due to shorts from insulation breakdown
Solution Approach 1:
The patent applies preliminary action by designing the interlayer insulating layer with contact holes positioned at a sufficient distance from gate electrodes before operation begins. This preventive structural design ensures that insulation breakdown does not occur during pixel operation, thereby maintaining display quality while enabling the lighting test transistor to provide data voltage to pixels.
Data Source
AI summary
A display device includes a substrate, a plurality of pixel columns, and a lighting test circuit unit. The lighting test circuit unit is disposed in a non-display area on the substrate, includes a plurality of lighting test transistors, and provides a lighting test voltage to the pixel columns. Each of the lighting test transistors includes an active pattern including a source area, a drain area, and a channel area, a gate electrode disposed in the channel area, an interlayer insulating layer including a first contact hole spaced apart from a first side of the gate electrode by about 7 um or more, and a source electrode contacting the source area of the active pattern through the first contact hole.