Etchant Composition for TFT Signal Line Profile Control
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Solution Overview
Problem
The increasing size of LCDs and OLEDs requires materials with low resistivity for gate and data lines, but these materials suffer from poor contact properties and chemical resistance issues, and multi-layered signal lines face profile degradation due to differences in etching speeds and galvanic effects between various metals.
Innovation Solution
An etchant composition containing phosphoric acid, nitric acid, acetic acid, and aluminum nitrate is used to control the etching speed of Al and Mo layers, preventing profile degradation by adjusting the concentrations of these acids to balance the etching speeds and mitigate galvanic effects, thereby forming signal lines with improved profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-layered signal lines are used to overcome poor contact property and chemical resistance, then contact property and chemical resistance are improved, but profile degradation occurs due to difference in etching speed between layers
Solution Approach 1:
The etchant composition parameters are specifically adjusted by controlling the concentration ratios of phosphoric acid (60-75 wt%), nitric acid (0.5-15 wt%), and acetic acid (2-15 wt%) to achieve balanced etching speeds for Al and Mo layers, resolving the profile degradation issue while maintaining the multi-layered structure benefits
Solution Approach 2:
A composite etchant system is formulated combining phosphoric acid, nitric acid, acetic acid, and aluminum nitrate, where each component contributes to selective etching control, enabling simultaneous optimization of etching performance for different metal layers without profile degradation
2Reliability
If multi-layered signal lines are used to overcome galvanic effect between different metals, then contact property is improved, but profile degradation is induced due to galvanic effect
Solution Approach 1:
The etchant composition parameters are optimized with specific concentration ranges of phosphoric acid (60-75 wt%) and nitric acid (0.5-15 wt%) to control the etching rates of different metals, balancing the galvanic effects and preventing profile degradation while maintaining good contact properties
Solution Approach 2:
Aluminum nitrate is introduced as an intermediary substance in the etchant composition that helps regulate the etching process between Al and Mo layers, mitigating the galvanic effect and preventing excessive etching of one layer over the other
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The etchant composition effectively prevents profile degradation of signal lines, ensuring stable and efficient formation of TFT array panels by maintaining balanced etching speeds and reducing the impact of galvanic effects, thus addressing the challenges of material contact and chemical resistance.
Implementation Method 1
an etchant containing phosphoric acid (H3PO4), nitric acid (HNO3), acetic acid (CH3COOH), and aluminum nitrate (Al(NO3)3)
Data Source
AI summary
The present invention provides an etchant composition containing 60 to 75 wt % of phosphoric acid (H3PO4), 0.5 to 15 wt % of nitric acid (HNO3), 2 to 15 wt % of acetic acid (CH3COOH), and 0.1 to 15 wt % of aluminum nitrate (Al(NO3)3).