Superconducting Airbridge Crossover Using Sacrificial Material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current superconducting airbridge crossover structures using resist as sacrificial material result in lossy residue and are not compatible with delicate tunnel junctions, leading to degraded performance and mechanical stress during fabrication.
Innovation Solution
The use of a superconducting sacrificial material that minimizes dielectric losses and is removed using vapor etching, such as XeF2, as a final step in device fabrication, allowing for the creation of a robust airbridge without damaging tunnel junctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resist material is used as sacrificial material in superconducting airbridge crossover structures, then the fabrication process is simple and easy to implement, but lossy residue remains after removal leading to degraded performance
Solution Approach 1:
The patent employs a sacrificial superconducting material layer that is intentionally deposited and then completely removed after serving its temporary purpose of defining the airbridge gap. This disposable approach ensures no lossy residue remains, eliminating dielectric losses while maintaining fabrication simplicity through standard deposition and removal processes.
Solution Approach 2:
The patent changes the material parameter from conventional resist to superconducting material, which can be deposited using standard superconducting fabrication techniques. This parameter change allows the sacrificial material to be removed completely without leaving lossy residue, thereby reducing dielectric losses while maintaining ease of manufacture through compatible processing methods.
2Ease of manufacture
If conventional sacrificial material removal processes are used, then the fabrication流程 is straightforward, but mechanical stress is applied to delicate tunnel junctions causing damage
Solution Approach 1:
The patent replaces mechanical removal methods (such as scraping or aggressive etching) with a chemical vapor deposition-based removal process. The sacrificial superconducting material is removed by selective etching that does not impose mechanical stress on the delicate tunnel junctions, thereby maintaining junction integrity while keeping the fabrication process straightforward.
Solution Approach 2:
The patent uses a specifically designed sacrificial superconducting material layer that acts as an intermediary. This layer can be selectively removed by chemical etching processes that do not affect the tunnel junctions, serving as a mediator that enables gap formation without mechanically stressing the sensitive junction structures.
3Loss of energy
If superconducting sacrificial material is used and removed by vapor etching, then residual material-related losses are minimized, but the fabrication process becomes more complex
Solution Approach 1:
The sacrificial superconducting material layer serves multiple functions: it defines the airbridge gap geometry, provides a removal interface for clean gap formation, and can be deposited using the same superconducting material deposition processes already used for other device components. This multi-functionality minimizes residual losses while avoiding significant increases in fabrication complexity.
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 approach reduces residual material-related losses and ensures compatibility with delicate tunnel junctions, enhancing the performance and mechanical robustness of the superconducting microwave structure.
Implementation Method 1
removing the superconducting sacrificial layer underneath the cross-over superconducting material
Data Source
AI summary
A technique relates to a superconducting airbridge on a structure. A first ground plane, resonator, and second ground plane are formed on a substrate. A first lift-off pattern is formed of a first lift-off resist and a first photoresist. The first photoresist is deposited on the first lift-off resist. A superconducting sacrificial layer is deposited while using the first lift-off pattern. The first lift-off pattern is removed. A cross-over lift-off pattern is formed of a second lift-off resist and a second photoresist. The second photoresist is deposited on the second lift-off resist. A cross-over superconducting material is deposited to be formed as the superconducting airbridge while using the cross-over lift-off pattern. The cross-over lift-off pattern is removed. The superconducting airbridge is formed to connect the first and second ground planes by removing the superconducting sacrificial layer underneath the cross-over superconducting material. The superconducting airbridge crosses over the resonator.