Superconducting Wire Buffer Layer Sputtering in the Transition Area
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Solution Overview
Problem
Conventional reactive magnetron sputtering techniques struggle to stabilize the formation of metal-oxide films for superconducting wires due to instability in the transition area between metal and oxide modes, resulting in low deposition rates and high production costs.
Innovation Solution
A method involving reactive magnetron sputtering with controlled oxygen gas concentrations to achieve stable emission intensities of metal species, forming high-rate buffer layers with Al2O3, Y2O3, and MgO layers, optimizing the transition area for enhanced deposition rates and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reactive magnetron sputtering is performed in the transition area between metal and oxide modes, then deposition rate increases, but film composition stability deteriorates
Solution Approach 1:
The patent employs real-time monitoring of plasma emission intensity as a feedback mechanism to dynamically control the sputtering process. By measuring the emission intensity of metal atoms in the plasma and comparing it to reference values, the system can automatically adjust oxygen flow rate and other parameters to maintain stable film composition while operating in the high-deposition-rate transition area. This feedback control resolves the contradiction by enabling the system to exploit the high productivity of the transition area while compensating for its inherent compositional instability.
Solution Approach 2:
The patent systematically varies critical process parameters including oxygen flow rate, radio frequency power, and gas pressure to optimize operation in the transition area. By carefully controlling these parameters, the process operates at the boundary between metal and oxide modes where deposition rate is maximized. The use of plasma emission intensity as a diagnostic tool allows precise mapping of parameter space to achieve stable operation in this high-productivity regime, resolving the contradiction between speed and stability.
2Ease of manufacture
If metal sputtering target is used with reactive magnetron sputtering, then production cost decreases, but film quality control becomes difficult
Solution Approach 1:
The patent replaces traditional mechanical/physical control methods with plasma-based diagnostic and control mechanisms. By using plasma emission spectroscopy to monitor the sputtering process in real-time, the system can detect and control film formation dynamics without relying solely on pre-set mechanical parameters. This substitution enables precise control of film quality while using cost-effective metal targets with reactive magnetron sputtering, resolving the contradiction between manufacturing ease and precision.
Solution Approach 2:
The patent introduces plasma emission intensity measurement as an intermediary parameter that bridges the gap between process control and film quality. This intermediary provides real-time information about the sputtering state, allowing indirect control of film composition and structure. By using this plasma-based intermediary, the system achieves precise film quality control while benefiting from the cost advantages of metal targets and reactive magnetron sputtering.
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 enables the fabrication of superconducting wires at higher production rates and lower costs by stabilizing the transition area in reactive magnetron sputtering, ensuring efficient formation of metal-oxide films.
Implementation Method 1
metal atoms sputtered from a metal sputtering target are deposited without reacting with the oxygen gas
Implementation Method 2
addition of oxygen gas as reactive gas for in situ oxidation of metal atoms in the magnetron plasma during deposition process
Implementation Method 3
reactive magnetron sputtering in which first oxygen gas as reactant gas and a sputtering target made of aluminium metal are used
Data Source
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AI summary
A method of fabricating a superconducting wire includes forming a buffer layer on the substrate, the buffer layer including an Al2O3 layer, the Al2O3 layer being formed by reactive magnetron sputtering in which first oxygen gas as reactant gas and a sputtering target made of aluminium metal are used, the Al2O3 layer being formed while being supplied the first oxygen gas at a first concentration, the first concentration being a concentration of the first oxygen gas at which an emission intensity of Al in plasma near a surface of the sputtering target is not less than 25% and not more than 80% of a first reference value, the first reference value being the emission intensity of Al at which the concentration of the first oxygen gas is zero; and forming a superconducting layer above the buffer layer.