Array Substrate Second Electrode Contamination Prevention
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Solution Overview
Problem
Existing liquid crystal display apparatuses face challenges in manufacturing due to contamination of the active layer by source and drain electrodes, leading to reduced aperture ratio and reliability, and complexities in the manufacturing process.
Innovation Solution
The array substrate design includes a second electrode that covers the upper and side surfaces of the source electrode, preventing contamination of the active layer and using a specific material stack for the electrodes and insulating layers to enhance reliability and uniformity, such as gallium doped zinc oxide (GZO) or indium doped zinc oxide (IZO) for the data and gate lines, and silicon nitride and silicon oxide for the insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the source and drain electrodes are exposed to the active layer during manufacturing, then the manufacturing process is simpler, but the active layer becomes contaminated and reliability decreases
Solution Approach 1:
A second electrode is introduced as an intermediary component between the source electrode and the active layer. This second electrode covers the upper and side surfaces of the source electrode, acting as a protective barrier that prevents metal atoms from the source electrode from contaminating the active layer during the manufacturing process, thereby resolving the contradiction between manufacturing simplicity and contamination prevention
2Area of stationary object
If the aperture ratio is increased, then the display performance is improved, but the risk of contamination and manufacturing complexity increase
Solution Approach 1:
The protective function is extended from a single-plane coverage to multi-dimensional coverage by having the second electrode cover not only the upper surface but also the side surfaces of the source electrode. This three-dimensional protective structure allows for larger aperture ratios while maintaining contamination prevention, as the side surface coverage ensures that metal atoms cannot reach the active layer from lateral directions
3Reliability
If different metal layers with different etch rates are used, then the electrical performance is optimized, but voids are formed and manufacturing uniformity decreases
Solution Approach 1:
The second electrode is formed beforehand to cover the side surfaces of the source electrode, creating a protective cushion that compensates for the void formation issue. When the first insulating layer is subsequently formed over the metal layers with different etch rates, the second electrode prevents voids from forming at the interfaces, ensuring uniform insulating layer formation while allowing the use of different metal materials for optimized electrical performance
Data Source
AI summary
An array substrate includes a thin film transistor which includes a gate electrode electrically connected to a gate line, a source electrode electrically connected to a data line, a drain electrode and an active layer, a first electrode electrically connected to the drain electrode and disposed at a pixel area, and a second electrode covering an upper and a side surface of the source electrode. The second electrode is spaced apart from the first electrode.