Etchant Composition for Copper-Titanium Multilayer Taper Control
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Solution Overview
Problem
In the flat display industry, high-definition displays require smaller metal patterns with precise taper angles to minimize defects like short-circuits, but existing etchant compositions struggle to maintain optimal taper angles during etching of copper and titanium multilayers, leading to inferior step coverage and increased defect likelihood.
Innovation Solution
An etchant composition comprising persulfate, a four-nitrogen ring compound, a carbonyl ring compound with two or more carbonyl groups, a fluorine compound, a three-nitrogen ring compound with a thiol group, hydrogen sulfate, sulfonic acid, and phosphoric acid or phosphate, which etches both titanium and copper layers in a batch, maintaining a stable taper angle and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width of metal pattern is decreased to achieve high definition resolution, then the resolution is improved, but the step coverage of stacked metal layers deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by incorporating specific additives (ammonium fluorosulfonate, heterocyclic compounds with nitrogen atoms, and carboxylic acid compounds) to modify the etching characteristics. This enables maintenance of appropriate taper angles even when metal pattern width is reduced, thereby improving resolution without sacrificing step coverage
2Productivity
If multiple metal layers are etched in a batch to increase productivity, then the etching efficiency is improved, but the control of taper angle deteriorates
Solution Approach 1:
The patent develops a universal etchant composition that can simultaneously etch different metal layers (copper and other metals) in a single batch process while maintaining appropriate taper angles for all layers. The multifunctional additives enable this composition to handle diverse metal etching requirements without compromising precision
Solution Approach 2:
By adjusting the chemical composition parameters of the etchant (specific ratios of persulfate, ammonium fluorosulfonate, heterocyclic compounds, and carboxylic acid compounds), the patent optimizes the etching process to maintain consistent taper angles across multiple metal layers etched simultaneously, thereby achieving both high productivity and 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 achieves excellent taper properties, minimizes wiring defects, and maintains stable etching performance even after reuse, ensuring high-quality metal patterns and array substrates with precise taper angles and reduced critical dimension skew.
Implementation Method 1
an etchant composition including from about 5 wt % to about 20 wt % of a persulfate
Implementation Method 2
from about 0.1 wt % to about 2 wt % of a four-nitrogen ring compound; from about 0.01 wt % to about 3 wt % of a carbonyl ring compound having two or more carbonyl groups
Data Source
AI summary
An etchant composition including a persulfate, a four-nitrogen ring compound, a carbonyl ring compound having two or more carbonyl groups, and water, and having a weight ratio of the four-nitrogen ring compound and the carbonyl ring compound of about 1:0.1 to about 1:2. The etchant composition may etch a multilayer of titanium/copper and may be used for manufacturing a metal pattern and an array substrate having excellent properties of an etched pattern.