Etching Aluminum Oxide Films Without Hydrogen Fluoride
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Solution Overview
Problem
Aluminum oxide films are difficult to etch using conventional solutions containing phosphoric acid and hydrochloric acid, and existing solutions with hydrogen fluoride are toxic and pose handling challenges, making it hard to achieve a practical etching rate for specific film densities.
Innovation Solution
An etching solution comprising 30% to 80% phosphoric acid, 10% or less nitric acid, and 0.0005% to 0.0050% surfactant is used to etch aluminum oxide films with a density of 2.80 g/cm3 to 3.25 g/cm3, avoiding the use of hydrogen fluoride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an etching solution containing hydrogen fluoride is used to etch aluminum oxide film, then the etching rate is improved, but the toxicity and handling difficulty increase
Solution Approach 1:
The patent extracts and removes hydrogen fluoride from the etching solution composition. The solution uses phosphoric acid as the main etching agent instead of hydrogen fluoride, completely eliminating the toxic substance while maintaining etching capability through alternative chemistry
Solution Approach 2:
The patent changes the chemical composition parameters of the etching solution by specifying phosphoric acid concentration (30-80 wt%), nitric acid concentration (10 wt% or less), and surfactant concentration (0.0005-0.0050 wt%). These parameter changes enable effective etching of aluminum oxide film with density 2.80-3.25 g/cm³ without using toxic hydrogen fluoride
2Object-affected harmful factors
If conventional etching solutions containing phosphoric acid and hydrochloric acid are used, then the handling safety is improved, but the etching rate deteriorates
Solution Approach 1:
The patent creates a composite etching solution formulation combining phosphoric acid (30-80 wt%), nitric acid (10 wt% or less), and surfactant (0.0005-0.0050 wt%). This composite composition achieves both safe handling and practical etching rate by synergistic interaction of components
Solution Approach 2:
The surfactant acts as an intermediary substance in the etching solution, facilitating the interaction between phosphoric acid and aluminum oxide film. The surfactant concentration (0.0005-0.0050 wt%) optimizes wetting and contact, enabling effective etching without requiring toxic hydrogen fluoride
3Reliability
If the aluminum oxide film density is increased to improve hydrogen barrier properties, then the protection performance is improved, but the etching difficulty increases
Solution Approach 1:
The patent specifies targeting aluminum oxide films with density of 2.80-3.25 g/cm³, which provides adequate hydrogen barrier properties while remaining etchable. The etching solution parameters (phosphoric acid 30-80 wt%, nitric acid ≤10 wt%, surfactant 0.0005-0.0050 wt%) are optimized for this density range to achieve practical etching rates
Solution Approach 2:
The invention applies local quality optimization by matching the etching solution composition specifically to the aluminum oxide film density characteristics. The solution formulation is tailored to work effectively with films in the 2.80-3.25 g/cm³ density range, achieving both protection and processability
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
This solution enables a practical etching rate for aluminum oxide films with specific densities, ensuring effective etching without the toxicity and handling issues associated with hydrogen fluoride, while maintaining hydrogen barrier properties.
Implementation Method 1
an aluminum oxide film can be etched with use of an etching solution containing phosphoric acid
Implementation Method 2
surfactant having concentration of 0.0005% by weight to 0.0050% by weight
Implementation Method 3
nitric acid having concentration of 10% by weight or less
Data Source
AI summary
An etching solution includes: phosphoric acid having concentration of 30% by weight to 80% by weight; nitric acid having concentration of 10% by weight or less; and surfactant having concentration of 0.0005% by weight to 0.0050% by weight, wherein the etching solution is used for etching an aluminum oxide film having film density of 2.80 g/cm3 to 3.25 g/cm3.