Ammonium Persulfate Etching Composition for Copper Alloy Taper Control
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Solution Overview
Problem
Conventional etching compositions for copper layers often result in excessive etching ratios, unstable taper angles, and reduced manufacturing margin and storage stability, leading to electrical resistance increases and etching failures, especially when dealing with copper alloy layers.
Innovation Solution
An etching composition comprising 0.1% to 30% ammonium persulfate, 0.1% to 10% sulfate, and 0.01% to 5% acetate by weight, with water making up the remainder, which effectively stabilizes the taper angle between 45° to 75° and maintains etching characteristics over time, suitable for copper and copper-manganese alloy layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching compositions (hydrogen peroxide-based) are used for copper layers, then etching capability is achieved, but manufacturing margin and storage stability are reduced due to decomposition and heat generation
Solution Approach 1:
The patent changes the chemical parameters of the etching composition by replacing hydrogen peroxide with ammonium persulfate as the main oxidizing agent. This parameter change eliminates the decomposition issue and heat generation problem while maintaining effective copper etching capability, thereby improving both manufacturing margin and storage stability
Solution Approach 2:
The patent uses ammonium persulfate which is more stable and easier to handle than hydrogen peroxide. The composition can be stored for extended periods without degradation, effectively replacing the unstable hydrogen peroxide-based solutions that require immediate use after preparation
2Manufacturing precision
If conventional etching compositions are used for copper alloy layers, then etching occurs, but taper angle becomes excessively small (lower than 20°) due to different etching ratios to metals in the alloy
Solution Approach 1:
The patent modifies the chemical composition parameters by adding specific organic compounds (carboxylic acid and its derivatives) to the ammonium persulfate-based etching solution. This composition adjustment optimizes the etching rate uniformity across different metals in the copper alloy, achieving a controlled taper angle between 45°-75°
Solution Approach 2:
The etching composition uses a composite chemical system combining ammonium persulfate (oxidizing agent) with carboxylic acid derivatives (etching rate controllers). This composite approach allows differential etching control on copper and alloying elements, producing the desired taper angle while maintaining etching effectiveness
3Manufacturing precision
If strong oxidizers are used to etch copper layers with low resistance, then etching capability is improved, but etching ratio to neighboring metal layers becomes excessively great
Solution Approach 1:
The patent adjusts the oxidizing strength parameter by using ammonium persulfate instead of stronger oxidizers like hydrogen peroxide or nitric acid. This provides sufficient etching capability for copper while inherently limiting the etching rate on neighboring metal layers, thus controlling the etching ratio and preventing excessive material removal
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 improves manufacturing margin and storage stability, ensuring a stable taper shape for metal patterns and enhancing the reliability and productivity of display substrate manufacturing by maintaining etching performance without deterioration.
Implementation Method 1
an etching composition for a copper layer, which includes hydrogen peroxide, an inorganic acid and a neutral salt... a strong oxidizer may be used for etching a copper layer... ammonium persulfate
Implementation Method 2
hydrogen peroxide decomposes into water and oxygen through disproportionation in the presence of a copper ion and an iron ion so that heat is generated and its composition rapidly changes
Data Source
AI summary
An etching composition for a copper-containing layer includes about 0.1% to about 30% by weight of ammonium persulfate, about 0.1% to about 10% by weight of a sulfate, about 0.01% to about 5% by weight of an acetate and about 55% to about 99.79% by weight of water. The etching composition having improved stability during storage and an increased capacity for etching.