Selective Etching of Titanium and Tungsten Metals Using Hydrogen Peroxide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching solutions for titanium-based and tungsten-based metals and their nitrides suffer from non-uniform etching, corrosion of substrates, and poor selectivity, leading to unstable etching rates and excessive foaming, which affects the precision and efficiency of semiconductor and MEMS device manufacturing.
Innovation Solution
An etching solution comprising 15-35 mass% hydrogen peroxide, 0.1-15 mass% ammonium citrate salt, and water, with optional addition of 0.005-4.5 mass% ammonia, which minimizes foaming and ensures selective etching of titanium-based and tungsten-based metals without etching other materials like aluminum, copper, or silicon substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydrofluoric acid/nitric acid mixtures or hydrogen peroxide/hydrofluoric acid mixtures are used for titanium-based metal etching, then etching rate is improved, but corrosion of silicon substrates and glass substrates occurs and aluminum wirings are etched
Solution Approach 1:
The patent changes the chemical composition parameters of the etching solution by replacing hydrofluoric acid with a mixture of hydrogen peroxide (15-35 mass%) and organic acid (0.1-15 mass%), maintaining effective etching capability while eliminating substrate corrosion and selective etching of aluminum wirings
Solution Approach 2:
The patent uses hydrogen peroxide as a temporary etching agent that decomposes into water and oxygen, providing effective etching action while leaving no harmful residues that would corrode substrates or affect other metal layers
2Speed
If hydrogen peroxide/phosphoric acid/ammonia mixtures are used to improve etching rate, then etching rate is improved, but intense foaming occurs causing bubble attachment onto substrate surface and non-uniform etching
Solution Approach 1:
The patent modifies the solution composition by using specific ratios of hydrogen peroxide (15-35 mass%) and organic acid (0.1-15 mass%) without phosphoric acid and ammonia, which suppresses foaming while maintaining stable etching rate and uniform etching across the substrate surface
Solution Approach 2:
The patent introduces organic acid as an intermediary substance that mediates between hydrogen peroxide and the metal surface, enabling controlled etching without the violent foaming reaction that occurs with phosphoric acid/ammonia mixtures
3Speed
If hydrogen peroxide-containing etching solutions are used, then etching rate is improved, but decomposition of hydrogen peroxide is rapid making stable etching impossible
Solution Approach 1:
The patent creates a continuous etching action by combining hydrogen peroxide with organic acid, where the organic acid continuously reacts with the metal surface while hydrogen peroxide provides sustained oxidation, maintaining stable etching rate throughout the process despite hydrogen peroxide decomposition
Solution Approach 2:
The patent uses a composite chemical system combining hydrogen peroxide and organic acid in specific proportions, where the two components work synergistically to provide both high etching rate and stable, controlled etching throughout the process
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 solution provides a stable and uniform etching process with high selectivity for titanium-based and tungsten-based metals, reducing foaming and maintaining a consistent etching rate, thereby enhancing the production efficiency of electronic devices without damaging substrates or other materials.
Implementation Method 1
An etching solution for titanium-based metals, tungsten-based metals, titanium/tungsten-based metals or their nitrides, which comprises 15-35 mass% hydrogen peroxide, 0.1-15 mass% of an organic acid salt
Implementation Method 2
wherein the organic acid salt is an ammonium salt of citric acid
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An etching solution for titanium-based metals, tungsten-based metals, titanium/tungsten-based metals, or their nitrides, which comprises hydrogen peroxide, an organic acid salt, and water. The etching solution can be used for uniform etching of titanium-based metals, tungsten-based metals, titanium/tungsten-based metals, or their nitrides, with little foaming, and an etching solution can be obtained having an excellent selective etching property for titanium-based metals, tungsten-based metals and titanium/tungsten-based metals with respect to other metals Or base materials.