Segmented ESD Device for LTPS TFT Film Layer Integrity
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Solution Overview
Problem
The manufacturing of low temperature poly-Si thin film transistor (LTPS-TFT) array substrates is prone to electrostatic discharge (ESD) damage during the cutting process due to stress accumulation between the electrostatic discharge device and other layers, leading to film layer breakage.
Innovation Solution
The electrostatic discharge device is divided into multiple units disposed at intervals, connected to the substrate and a conductive circuit, reducing internal stress and providing elastic deformation spaces to prevent film layer breakage during cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal guard ring with heavily-doped poly-Si electrostatic discharge devices is manufactured at the periphery of the display area, then electrostatic discharge damage to devices is prevented, but stress accumulation between the electrostatic discharge device film layer and other layers occurs due to large thickness and different coefficient of thermal expansion
Solution Approach 1:
The electrostatic discharge device is divided into multiple units disposed at intervals rather than forming a continuous heavy-doped poly-Si guard ring. This segmentation reduces the overall thickness and thermal expansion differential, thereby reducing stress accumulation between the electrostatic discharge device film layer and other layers while maintaining ESD protection capability.
2Reliability
If heavily-doped poly-Si is used for the electrostatic discharge device, then electrostatic discharge protection is achieved, but large differences in film layer structure compared to other regions result in step formation
Solution Approach 1:
The electrostatic discharge device is segmented into multiple discrete units spaced at intervals rather than a continuous heavily-doped poly-Si structure. This segmentation reduces the area of structural difference, minimizing step formation between the electrostatic discharge device regions and other regions of the substrate.
3Productivity
If the array substrate and color filter substrate are cut after assembly, then integrated display panel is formed, but the heavily-doped poly-Si electrostatic discharge devices bear large stress due to steps, causing film layer breakage
Solution Approach 1:
The electrostatic discharge device is divided into multiple units with intervals between them, which reduces stress concentration and eliminates step formation. This segmented structure maintains film layer integrity during the cutting process after substrate and color filter substrate assembly, preventing film layer breakage.
Solution Approach 2:
The patent designs the electrostatic discharge device structure in advance to avoid step formation and stress concentration before the cutting process occurs. By using segmented units with intervals rather than a continuous heavily-doped structure, the design preemptively cushions against the stress that would otherwise cause film layer breakage during cutting.
Data Source
AI summary
The present disclosure discloses a thin film transistor array substrate, a display panel and a display device. The array substrate includes a substrate and an electrostatic discharge circuit layer, and the electrostatic discharge circuit layer is disposed in the non-display area at a side of the substrate and includes a conductive circuit disposed around the display area and electrostatic discharge devices electrically connected with the conductive circuit. The electrostatic discharge device includes a plurality of electrostatic discharge units disposed at intervals, one end of each of the electrostatic discharge units is connected with an edge of the substrate and the other end thereof is connected with the conductive circuit.