Copper Substrate for Superconducting Wire
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Solution Overview
Problem
Conventional methods for manufacturing substrates for epitaxial growth, such as high-temperature oxide superconducting wires, face challenges in achieving sufficient biaxial crystal orientation and surface smoothness due to high-temperature heat treatment, which can lead to deterioration of surface roughness and reduced production efficiency.
Innovation Solution
A 2-stage heat treatment process is employed to control the peak shape of the copper layer using X-ray diffraction, achieving a full width at half maximum of within 5° and a tail width of within 15°, resulting in high biaxial crystal orientation and surface smoothness, with a nickel protective layer formed to enhance these properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature heat treatment is performed to achieve high biaxial crystal orientation of copper layer, then crystal orientation is improved, but surface roughness deteriorates
Solution Approach 1:
The heat treatment process is divided into two distinct stages: first heat treatment (500-700°C for crystal orientation) and second heat treatment (800-950°C for surface smoothing). This segmentation allows each stage to optimize for its specific purpose without compromising the other, resolving the contradiction between achieving high crystal orientation and maintaining surface smoothness.
Solution Approach 2:
The first heat treatment is performed as a preliminary action to establish high biaxial crystal orientation before the second heat treatment is applied. By pre-establishing the crystal orientation in the first stage, the subsequent second heat treatment can focus on smoothing the surface without significantly degrading the already-established crystal orientation.
2Manufacturing precision
If heat treatment time is extended to improve crystal orientation, then biaxial crystal orientation is improved, but production efficiency decreases
Solution Approach 1:
The extended heat treatment process is segmented into two efficient stages with optimized time allocations. The first heat treatment uses 5-30 minutes to achieve sufficient crystal orientation, and the second heat treatment uses 5-60 minutes for surface smoothing. This segmentation eliminates the need for excessively long single-stage heat treatment, thereby improving production efficiency while maintaining high crystal orientation.
3Shape
If nickel layer is provided on copper layer to protect surface, then surface smoothness is maintained, but crystal orientation of nickel layer deteriorates
Solution Approach 1:
The first heat treatment is performed as a preliminary action to establish high biaxial crystal orientation of the copper layer before the nickel layer is formed. By pre-establishing the crystal orientation foundation in the copper layer, the subsequent nickel layer deposition and second heat treatment can maintain surface smoothness while the nickel layer inherits the underlying crystal orientation from the copper layer.
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 process enables the production of substrates with high biaxial crystal orientation and surface smoothness, improving the adhesion and crystal orientation of subsequent layers, while maintaining surface smoothness and preventing secondary recrystallization.
Implementation Method 1
a copper layer which has been subjected to heat treatment and has a biaxial crystal orientation in which a drift angle of a (100) crystal plane is within ±5°
Implementation Method 2
biaxial crystal orientation in which a drift angle of a (100) crystal plane is within ±5°
Implementation Method 3
peak shape of a copper layer within a predetermined range when a peak shape of a copper layer is controlled based on a pole figure obtained by the X-ray diffraction
Implementation Method 4
a nickel protective layer formed to enhance these properties
Data Source
Figure 1
Figure 2
AI summary
An objective of the present invention is to provide a copper substrate for epitaxial growth, which has higher biaxial crystal orientation, and a method for manufacturing the same. The substrate for epitaxial growth of the present invention contains a biaxially crystal-oriented copper layer, wherein the full width at half maximum Δφ of a peak based on the pole figure of the copper layer is within 5° and the tail width Δβ of the peak based on the pole figure is within 15°. Such a substrate for epitaxial growth is manufactured by a 1st step of performing heat treatment of a copper layer so that Δφ is within 6° and the tail width Δβ is within 25°, and after the 1st step, a 2nd step of performing heat treatment of the copper layer at a temperature higher than the temperature for heat treatment in the 1st step, so that Δφ is within 5° and the tail width Δβ is within 15°.