Titanium Seed Layer Etching Composition for Copper-Safe Removal
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Solution Overview
Problem
Existing etching methods for titanium and titanium alloys suffer from instability of hydrogen peroxide, leading to inefficient removal of titanium seed layers while causing elution of other metals like copper or copper alloys.
Innovation Solution
An aqueous etching composition comprising hydrogen peroxide, fluoride, a halide ion other than fluoride, and water, with specific concentration ranges, effectively removes titanium and titanium alloys while suppressing the etching of copper or copper alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen peroxide and sulfuric acid are used for etching titanium seed layer, then titanium removal is achieved, but stability is insufficient and other metals like copper elute
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by replacing sulfuric acid with a specific combination of hydrofluoric acid (0.01-0.5 mass%) and nitric acid (0.1-5 mass%), while controlling hydrogen peroxide concentration (0.1-5 mass%). This parameter optimization achieves both rapid titanium removal and solution stability, preventing copper elution while maintaining etching effectiveness.
2Productivity
If conventional etching methods are used to remove titanium seed layer, then titanium is removed, but other metals such as copper or copper alloy, cobalt etc. elute
Solution Approach 1:
The patent applies local quality by creating an etching solution with non-uniform chemical characteristics - using hydrofluoric acid specifically targeted at titanium oxidation, while nitric acid and hydrogen peroxide provide controlled oxidation that spares copper and cobalt. This localized chemical action allows selective titanium removal without harmful elution of other metals.
Solution Approach 2:
The patent introduces hydrofluoric acid as an intermediary substance that mediates the etching process. It forms stable fluorocomplexes with titanium, facilitating selective titanium removal. The nitric acid and hydrogen peroxide act as intermediary oxidizing agents that prepare the titanium surface for fluorocomplex formation without directly attacking copper or cobalt metals.
3Productivity
If etching solution contains strong oxidants, then titanium etching is enhanced, but copper and other metals are also etched
Solution Approach 1:
The patent applies partial action by using low concentrations of strong oxidants (hydrogen peroxide 0.1-5 mass%, nitric acid 0.1-5 mass%) that are sufficient to activate titanium surface oxidation but insufficient to cause significant copper etching. This partial oxidation approach, combined with hydrofluoric acid's selective titanium complexation, achieves high selectivity while maintaining adequate etching rate.
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 enables rapid removal of titanium and titanium alloys while preventing the elution of other metals, thereby improving the production efficiency of electronic parts with fine copper wiring.
Implementation Method 1
an etching composition comprising hydrogen peroxide, fluoride, a halide ion other than fluoride, and water
Implementation Method 2
the content of the fluoride (B) is 0.2 to 3 mass % based on the total amount of the composition
Data Source
AI summary
An etching method for quickly removing a seed layer that is formed of titanium and/or a titanium alloy, while suppressing dissolution of other metals from copper wiring lines and the like, for continuous and stable processing; and a composition which is used for this etching method. The composition comprises, based on a total amount of the composition, 0.01 to 0.23% by mass hydrogen peroxide, 0.2 to 3% by mass fluoride, 0.0005 to 0.025% by mass of a halide ion other than a fluoride ion, and water. A method for using the composition to produce a substrate is also described.