Silver-Layer Etchant Composition for Selective Over-Etch Control
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Solution Overview
Problem
Existing etchants for silver-containing films cause over-etching, leading to defects such as staining and damage to underlying films, particularly in reflective displays and thin film transistor substrates.
Innovation Solution
An etchant composition comprising an inorganic acid, inorganic sulfate, and two or more organic sulfur compounds, with specific molar mass ratios, is used to uniformly etch silver layers while minimizing damage and residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etchants (nitric acid, phosphoric acid, or acetic acid) are used to etch silver or silver alloy films, then etching can be performed, but over-etching occurs leading to short-circuiting of silver-containing wiring and damage to underlying films
Solution Approach 1:
The patent changes the chemical parameters of the etching system by introducing a specific composition ratio of inorganic acid (1-30 wt%), inorganic sulfate (5-30 wt%), organic sulfur compounds (10-30 wt%), and organic acid (20-60 wt%). This parameter optimization ensures controlled etching rate and prevents over-etching while maintaining effective silver film removal.
Solution Approach 2:
The patent uses a composite etching system combining four different types of chemicals (inorganic acid, inorganic sulfate, organic sulfur compounds, and organic acid) working synergistically. This composite approach provides balanced etching capability that selectively removes silver without damaging underlying films, resolving the contradiction between etching effectiveness and damage prevention.
2Manufacturing precision
If multiple etching treatments are applied to silver or silver alloy films, then more complete etching is achieved, but etching deviation increases significantly causing defects such as staining or damage to underlying films
Solution Approach 1:
The patent develops a universal etching composition that performs multiple functions simultaneously: etching silver, preventing over-etching, avoiding staining, and protecting underlying films all in a single treatment step. This multi-functional formulation eliminates the need for multiple sequential etching treatments that would otherwise be required to achieve complete etching.
Solution Approach 2:
The optimized composition parameters (specific weight percentages of each component) enable a single etching treatment to achieve the same level of completeness that would otherwise require multiple treatments, while maintaining film integrity through controlled chemical reactivity.
3Productivity
If higher flow rate is used to improve etching efficiency, then etching speed increases, but over-etching occurs leading to short-circuiting of wiring
Solution Approach 1:
The patent optimizes the concentration parameters of the etching composition so that effective etching can be achieved at lower flow rates. The balanced composition of four chemical components provides sufficient etching power at reduced flow conditions, preventing over-etching while maintaining productive etching speed.
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 composition effectively prevents over-etching and reduces defects, ensuring uniform etching and minimal damage to underlying films, enhancing the integrity of reflective displays and thin film transistor substrates.
Implementation Method 1
an inorganic acid; an organic acid
Implementation Method 2
two or more organic sulfur compounds
Data Source
AI summary
The present invention relates to a composition for selectively etching metal film containing silver (Ag), and a method for producing the same, which can selectively etch the single film of silver (Ag) or a silver alloy, or a multilayer film containing the metal film and an indium oxide film, while preventing damage to an underlying film, residue, and staining.