Selective TiO2 Etchant for Protecting Aluminium Oxide Layers
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Solution Overview
Problem
Existing methods for fabricating semiconductor-superconductor hybrid devices face challenges in selectively removing titanium dioxide without damaging the underlying aluminium oxide layer, which is crucial for maintaining the integrity and performance of the device.
Innovation Solution
An aqueous solution of ammonia and hydrogen peroxide is used as an etchant, with a molar ratio of ammonia to hydrogen peroxide ranging from 1:34 to 1:38, to selectively etch titanium dioxide while preserving the aluminium oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to remove titanium dioxide, then titanium dioxide can be etched, but the aluminium oxide layer is damaged
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by using a specific mixture of ammonia and hydrogen peroxide in controlled concentrations and ratios. This chemical parameter adjustment enables selective etching of titanium dioxide while preserving aluminium oxide, resolving the contradiction between etching effectiveness and layer integrity
Solution Approach 2:
The ammonia-hydrogen peroxide solution acts as an intermediary chemical agent that mediates between the titanium dioxide mask and the aluminium oxide layer. It selectively reacts with titanium dioxide through chemical oxidation while being inert to aluminium oxide, thus protecting the underlying layer while achieving complete mask removal
2Productivity
If aggressive etching is applied to ensure complete removal of titanium dioxide, then etching completeness improves, but damage to aluminium oxide increases
Solution Approach 1:
The etching solution exhibits local quality by having different chemical reactivity toward different materials in the structure. It is highly reactive toward titanium dioxide (high etching rate) while being non-reactive toward aluminium oxide (zero damage), achieving both high productivity and selectivity simultaneously through material-specific chemical properties
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 proposed etchant effectively removes titanium dioxide with good selectivity over aluminium oxide, ensuring the protection and integrity of the aluminium oxide layer, which is essential for the performance of semiconductor-superconductor hybrid devices.
Implementation Method 1
The etchant is an aqueous solution of a base and a hydroperoxide... effectively removing titanium dioxide without destroying an aluminium oxide layer
Data Source
AI summary
In some examples of the disclosed technology, a method comprises etching titanium dioxide selectively in the presence of aluminium oxide using an etchant. The etchant can be an aqueous solution of a base and a hydroperoxide. In some examples, the etchant is effective for removing titanium dioxide without destroying an aluminium oxide layer. Examples of an etchant for etching titanium dioxide are disclosed, where the etchant is an aqueous solution of ammonia and hydrogen peroxide, and in some examples the molar ratio of the ammonia to the hydrogen peroxide is in the range 1:34 to 1:38. Methods of etching titanium dioxide disclosed herein can be used to fabricate semiconductor-superconductor hybrid devices.