Etchant Composition for Multilayer Metal Pattern Taper Control
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Solution Overview
Problem
The challenge in the flat display industry is to achieve high resolution, large-size, and 3D displays with quicker response times, which requires narrower metal patterns in circuit boards, leading to inferior step coverage and defects in stacked metal layers, especially when using copper as the metal pattern material, necessitating an etchant composition that maintains appropriate taper angles and supports batch-type etching.
Innovation Solution
An etchant composition comprising persulfate, a four-nitrogen ring compound, a two-chlorine compound, a fluorine compound, and water, with specific weight ratios, optionally including hydrogen sulfate, sulfonic acid, antioxidant, acidity regulator, phosphate, and copper salt, is used to etch multilayer metal patterns, particularly those with copper and titanium layers, to achieve excellent taper shapes and minimize wiring defects like short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width of metal pattern is decreased to achieve high resolution, then the resolution is improved, but the step coverage of stacked metal layers deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by incorporating specific additives (complexing agents, surfactants, and chelating agents) that modify the etching kinetics. This allows control over the etching rate and profile, achieving both narrow linewidths for high resolution and improved step coverage by reducing undercut formation during the etching process
2Reliability
If copper is used as metal pattern material to achieve excellent electroconductivity, then the electrical performance is improved, but the adhesion and patterning quality deteriorate
Solution Approach 1:
The patent introduces intermediary substances in the etching solution, specifically complexing agents and surfactants, that mediate between the copper metal and the etchant. These intermediaries form temporary complexes with copper ions during etching, controlling the release of copper ions and preventing rapid dissolution that would lead to poor patterning quality, while still allowing the copper to maintain its excellent electroconductivity
Solution Approach 2:
The patent modifies the chemical environment parameters by adding specific compounds that change the etching mechanism for copper. The complexing agents alter the solubility and release rate of copper ions, enabling precise control over copper etching to achieve good adhesion and patterning quality while preserving the inherent electroconductivity of copper
3Productivity
If batch type etching is performed to increase productivity, then the manufacturing efficiency is improved, but the control over taper angle deteriorates
Solution Approach 1:
The patent incorporates buffering agents and pH control mechanisms in the batch etching solution that provide feedback control over the etching process. As etching proceeds and copper ions are released, the buffering system maintains stable pH conditions and the complexing agents continuously adjust to the changing ion concentration, ensuring consistent taper angle control throughout the batch process and enabling high productivity without sacrificing precision
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 forms metal patterns with small critical dimension skew and taper angles, minimizing precipitate generation and improving step coverage, thereby enhancing the manufacturing of array substrates and display devices with improved etching properties and reduced defects.
Implementation Method 1
an etchant composition which may keep an appropriate taper angle for patterning a multilayer metal pattern including a copper layer
Implementation Method 2
an etchant composition including a persulfate; a four-nitrogen ring compound; a two-chlorine compound, a fluorine compound, and water, wherein a weight ratio of the four-nitrogen ring compound and the two-chlorine compound is from about 1:0.5 to about 1:4
Data Source
AI summary
An etchant composition of an embodiment includes a persulfate, a four-nitrogen ring compound, a two-chlorine compound, a fluorine compound and water, and has a weight ratio of the four-nitrogen ring compound and the two-chlorine compound of about 1:0.5 to about 1:4. The etchant composition may etch a multilayer metal substrate of titanium/copper and may be used for manufacturing a multilayer metal pattern and an array substrate having excellent properties of etched patterns.