Nano-Scale SQUID Manufacturing via Insulating Interlayer
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Solution Overview
Problem
Current nano-scale superconducting quantum interference devices face limitations due to nano junctions being longer than their coherence length and superconducting ring thickness being constrained by the nano junction, affecting device performance.
Innovation Solution
A manufacturing method involving multiple steps: growing superconducting material layers with insulating interlayers and forming nanowires to create nano junctions, allowing for independent control of nano junction length and ring size, reducing the nano junction length and ring thickness to match coherence length, and using electron beam lithography to achieve precise dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the nano junction length is reduced to match the coherence length, then the sensitivity and performance of the device is improved, but the manufacturing precision and control difficulty increase significantly
Solution Approach 1:
The patent introduces an insulating interlayer as an intermediary element between the two superconducting layers. This insulating interlayer serves as a spacer that precisely controls the length of the nano junction by its thickness, which can be accurately controlled during the layer growth process. This mediator approach transfers the control parameter from direct nanowire width control to insulating layer thickness control, significantly improving manufacturability while maintaining the required nano junction length for high sensitivity
Solution Approach 2:
The patent changes the control parameter from horizontal dimensions (nanowire width and length) to vertical dimensions (insulating interlayer thickness). By controlling the thickness of the insulating interlayer during the layer-by-layer growth process, the nano junction length can be precisely controlled without the extreme manufacturing precision requirements of traditional lateral patterning methods
2Measurement precision
If the superconducting ring thickness is reduced independently, then the inductance is reduced and sensitivity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the superconducting ring into two separate superconducting material layers grown at different times. The first superconducting layer is grown, then an insulating interlayer is deposited, followed by growth of the second superconducting layer. This segmentation allows independent control of the ring thickness (determined by the first layer thickness) and the nano junction length (determined by the insulating interlayer thickness), simplifying the manufacturing process while improving device performance
Solution Approach 2:
The patent transitions from controlling ring thickness and junction length in the same lateral dimension to controlling them in different dimensions. The ring thickness is controlled by the vertical thickness of the first superconducting layer, while the junction length is controlled by the vertical thickness of the insulating interlayer. This dimensional separation allows independent optimization of both parameters without increasing manufacturing complexity
3Ease of manufacture
If electron beam lithography or focused-ion-beam etching is used to directly etch the planar structure, then the manufacturing process is simple and intuitive, but the minimum size of the superconducting ring is limited to about 50 nm
Solution Approach 1:
The patent replaces the mechanical etching process (electron beam lithography or focused-ion-beam etching) with a layer-by-layer deposition process. Instead of using high-energy beams to remove material and define patterns, the invention uses sequential growth of superconducting and insulating layers to self-defined the nano junction structure. This substitution eliminates the 50 nm size limitation imposed by the resolution of beam-based etching methods while maintaining manufacturing simplicity
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 method enables the creation of nano-scale superconducting quantum interference devices with improved sensitivity and reduced critical current, enhancing the detection of small spin ensembles and magnetic properties without the need for magnetic shielding.
Implementation Method 1
growing a first superconducting material layer on the substrate; growing a second superconducting material layer on the insulation material
Implementation Method 2
The superconducting quantum interference device (SQUID) is an extremely sensitive magnetic sensor by taking advantage of the Josephson effect
Data Source
AI summary
A nano-scale superconducting quantum interference device and a manufacturing method thereof, comprising the following steps of: S1: providing a substrate and growing a first superconducting material layer thereon; S2: forming a photo-resist layer and performing patterning; S3: etching the first superconducting material layer in a predetermined region; S4: covering a layer of insulation material on a top and a side of a structure obtained in step S3; S5: growing a second superconducting material layer; S6: removing the structure above the plane where the upper surface of the first superconducting material layer locates, to obtain a plane superconducting structure, in the middle of which at least one insulating interlayer is inserted; S7: forming at least one nanowire vertical to the insulating interlayer, to obtain the nano-scale superconducting quantum interference device. The width of the superconducting ring and the length of the nano junction are determined by the insulating interlayer.