TFT Array Panel Signal Line Design for LCD Reliability
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Solution Overview
Problem
In liquid crystal display (LCD) manufacturing, the increased resistance of signal lines due to larger sizes leads to signal delay and voltage drop, and direct contact between aluminum (Al) signal lines and indium tin oxide (ITO) can result in oxidation or corrosion, affecting the reliability and performance of the display.
Innovation Solution
A thin film transistor (TFT) array panel design with a substrate, signal lines, gate insulating layer, semiconductors, and passivation layers, where the signal lines include a conductive layer of aluminum or its alloy, and the use of a manufacturing method involving amorphous silicon layers and photoresist films to form contact holes and connect conductors, preventing direct contact oxidation by eliminating exposed Al portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum signal lines are used to reduce resistance, then signal delay and voltage drop are reduced, but oxidation and corrosion occur when Al contacts ITO directly
Solution Approach 1:
A barrier layer is introduced as an intermediary between the aluminum signal line and the ITO pixel electrode. This barrier layer prevents direct contact between Al and ITO, thereby preventing oxidation and corrosion while maintaining the low resistance properties of the aluminum signal line.
Solution Approach 2:
The signal line structure is designed as a composite multi-layer structure combining aluminum signal lines with a barrier layer. This composite structure provides both the electrical conductivity of aluminum and the protective properties of the barrier layer against oxidation and corrosion.
2Area of stationary object
If the size of LCD increases, then display area is improved, but resistance of signal lines increases causing signal delay and voltage drop
Solution Approach 1:
The signal line is constructed as a multi-layer composite structure with aluminum layers providing low resistance and copper layers providing enhanced conductivity. This composite structure reduces overall resistance even as signal line length increases with larger display areas, thereby maintaining signal transmission quality.
Solution Approach 2:
The signal line structure serves multiple functions: the aluminum layers provide low resistance and cost-effectiveness, while the copper layers provide enhanced conductivity and oxidation resistance. This multi-functional design allows the signal line to maintain performance across varying display sizes.
Data Source
AI summary
A thin film transistor (TFT) array panel includes a substrate, a first signal line formed on the substrate, a gate insulating layer formed on the first signal line and having a first contact hole exposing a portion of the first signal line, a first semiconductor formed on the gate insulating layer, a second signal line formed on the first semiconductor and the gate insulating layer and a drain electrode formed on the first semiconductor and separated from the second signal line. The TFT array panel further includes a conductor formed on the gate insulating layer and connected to the first signal line through the first contact hole, a passivation layer formed on the second signal line, the drain electrode, and the conductor, and having a second contact hole exposing the drain electrode and a pixel electrode formed on the passivation layer and connected to the drain electrode through the second contact hole.