SQUID Array Inductance Spread via Segmented Fabrication

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Solution Overview

Problem

Existing methods struggle to produce high-Temperature (high-Tc) SQUID arrays with large variation in loop sizes while maintaining control over Josephson junction uniformity, as photolithographic processes often result in overexposure and narrower junction widths.

Innovation Solution

A hybrid array of SQUIDs and bi-SQUIDs with varying effective geometric magnetic inductance parameter values, utilizing the same feature dimensions to achieve a Gaussian distribution of βL values, allowing for a large spread in magnetic inductance without overexposure issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If photolithographic exposure is used to fabricate SQUID arrays with varied loop sizes, then the manufacturing process is simplified, but the Josephson junction widths become narrower than intended due to overexposure

Engineering Contradiction:

Improvefabrication process simplicityVSAvoidJosephson junction width accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention segments the fabrication approach by creating multiple groups of SQUIDs, where each group is fabricated with identical dimensions using the same photolithographic exposure parameters. This segmentation prevents overexposure within each group while maintaining process simplicity, as no complex variable exposure control is needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the design parameters by varying the loop area and magnetic inductance at the group level rather than at the individual SQUID level. This parameter change strategy allows the use of fixed photolithographic exposure settings for all groups, avoiding overexposure while still achieving the desired overall spread in βL values across the array.

Inventive Principle:

Principle #35Parameter changes

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 production of high-Tc SQUID arrays with desired critical current values and improved linearity in the V-Φ characteristic response, overcoming the limitations of photolithographic processes by maintaining uniformity and preventing overexposure.

Implementation Method 1

Josephson junction is a region of material that provides a weak link between two fully superconducting regions

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

Superconducting Quantum Interference Devices (SQUIDs) are comprised of tiny loops of superconducting material in which Josephson junctions are placed in the loop path

Methodology Applied

Scientific EffectQuantum interference:

Data Source

PatentUS10847573B1Method for producing SQUID arrays composed of SQUID elements having large spread in magnetic inductance values and comparable internal dimensions

Publication Date: 2020.11.24 THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

A device is disclosed that includes a substrate, a first superconducting quantum interference device (SQUID), a second SQUID and a third SQUID. The first SQUID is disposed on the substrate and has a first feature dimension, a second feature dimension and a first effective geometric magnetic inductance parameter value, βL1. The second SQUID is disposed on the substrate and has the first feature dimension, a third feature dimension and a second effective geometric magnetic inductance parameter value, βL2. The third SQUID is disposed on the substrate and has the first feature dimension, a fourth feature dimension and a third effective geometric magnetic inductance parameter value, βL3, wherein βL1<βL2<βL3.