Josephson Junction Fabrication via Homogeneous EBID

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Solution Overview

Problem

Conventional Josephson junctions require multiple processing steps and materials, leading to inconsistent electrical behavior, increased fabrication time, and risk of cross-contamination, especially when dealing with mechanically fragile or chemically sensitive structures.

Innovation Solution

Fabricating Josephson junctions with superconducting electrodes and intermediate barriers made from the same chemical elements in pristine condition using electron beam-induced deposition (EBID), allowing for direct writing and minimizing post-processing steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional heterogeneous Josephson junctions are fabricated using multiple distinct materials for superconducting electrodes and intermediate barrier, then electrical transport properties can be distinguished, but the number of processing steps increases, fabrication time increases, and risk of cross-contamination increases

Engineering Contradiction:

Improveelectrical transport propertiesVSAvoidnumber of processing steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies homogeneity by fabricating both the superconducting electrodes and the intermediate barrier from the same material (e.g., tungsten carbide deposited via EBID). This eliminates material interfaces and simplifies the fabrication process to a single step, while maintaining reliable electrical transport properties through controlled variations in deposition parameters rather than material composition

Inventive Principle:

Principle #33Homogeneity

Solution Approach 2:

The patent merges the fabrication of superconducting electrodes and intermediate barrier into a single processing step using electron beam-induced deposition. By using the same precursor and deposition conditions for both components, the method combines what were previously separate fabrication steps into one unified process, reducing complexity and cross-contamination risk

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If conventional Josephson junctions are fabricated with multiple processing steps, then electrical transport properties can be controlled, but fabrication time increases and risk of inconsistent electrical behaviour increases

Engineering Contradiction:

Improveelectrical behaviour consistencyVSAvoidfabrication time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by depositing both the superconducting electrodes and intermediate barrier simultaneously in a single EBID process step. The electron beam is programmed to deposit material in the correct spatial pattern beforehand, eliminating the need for subsequent processing steps and ensuring consistent electrical behavior across multiple junctions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent controls electrical transport properties by changing deposition parameters (electron beam current, scanning speed, dwell time) rather than material composition. By varying these parameters during the single deposition step, the method achieves precise control over the electrical characteristics of both electrodes and barrier without requiring multiple processing steps

Inventive Principle:

Principle #35Parameter changes

3Shape

If post-processing steps are applied to Josephson junctions, then structural integrity can be modified, but the pristine condition of superconducting electrodes and barrier is altered or damaged

Engineering Contradiction:

Improvestructural integrityVSAvoidpristine condition

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The EBID process is self-service in that it directly writes the Josephson junction structure in its final form without requiring subsequent processing steps. The electron beam deposits material precisely where needed, creating the complete junction structure including electrodes and barrier in a single step, thereby preserving the pristine condition of the superconducting materials

Inventive Principle:

Principle #25Self-service

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 simplifies the fabrication process, reduces inconsistencies, and enables reliable electrical control, facilitating the production of Josephson junctions on complex or sensitive surfaces with improved reliability and reduced processing time.

Implementation Method 1

Fabricating Josephson junctions with superconducting electrodes and intermediate barriers made from the same chemical elements in pristine condition using electron beam-induced deposition (EBID)

Methodology Applied

Scientific EffectElectron beam-induced deposition (EBID):

Implementation Method 2

The Josephson effect arises when macroscopic quantum states are separated by a medium that allows their wavefunctions to partially overlap. The phenomenon is realised in Josephson junctions in which the macroscopic wavefunctions of superconducting electrodes are coupled via some form of barrier.

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentUS20230103370A1Junction, device and methods of fabrication

Publication Date: 2023.04.06 LEIDEN UNIVERSITY

AI summary

A Josephson junction comprises superconducting electrodes (20) interconnected via an intermediate Josephson barrier (22), wherein the superconducting electrodes (20) and the intermediate Josephson barrier (22) are made out of the same chemical elements and are in a pristine condition.