Josephson Junction Test Structure for Damage-Free Quantum Chip Probing

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Solution Overview

Problem

Conventional methods fail to perform electrical tests on superconducting Josephson junctions due to structural sensitivity and potential microstructural damage, making electrical contact testing challenging for quantum chips.

Innovation Solution

A quantum chip test structure is developed, featuring a superconducting Josephson junction with a connection structure on a substrate, isolation layers, and an electrical connection layer that allows for electrical contact with a test device without damaging the junction, using easily peeling-off conductive materials and undercut structures to facilitate testing and removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrical contact testing is performed on superconducting Josephson junctions, then test efficiency is improved, but the junction may suffer microstructural damage due to its structural sensitivity

Engineering Contradiction:

Improvetest efficiencyVSAvoidjunction integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces an electrical connection structure as an intermediary between the test device and the superconducting Josephson junction. This connection structure includes connection electrodes and isolation layers that mediate the electrical contact, allowing testing to be performed without direct contact that would damage the sensitive junction. The intermediary structure protects the junction while enabling electrical measurements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the testing system into distinct functional components: the superconducting Josephson junction, the electrical connection structure, and the test device. By separating the junction from direct contact with the test device through the electrical connection structure, the system enables testing while protecting the junction's integrity.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If test structures are added to the quantum chip, then testing capability is improved, but device complexity increases

Engineering Contradiction:

Improvetesting capabilityVSAvoidchip structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The electrical connection structure serves multiple functions: it provides electrical contact for testing, isolates the junction from direct contact, and maintains the superconducting pathway. By making the connection structure multi-functional, the patent adds testing capability without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the electrical connection function with the isolation function into a single integrated structure. The connection electrodes and isolation layers work together as a unified electrical connection structure, reducing the number of separate components needed and simplifying the overall chip design while providing both testing capability and protection.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables efficient and accurate electrical contact testing of superconducting Josephson junctions, improving test efficiency and minimizing damage to the quantum chip, while allowing for easy removal of the test components without affecting the chip's performance.

Implementation Method 1

an electrical connection layer located in the deposition window, where the electrical connection portion has one end connected to the connection structure and the other end connected to the electrical connection layer, and the electrical connection layer is configured to implement electrical contact with a test device

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The closed-loop apparatus is constituted by Josephson junctions connected in parallel, where the Josephson junction, also referred to as a superconducting tunnel junction, is generally a structure formed by sandwiching a very thin barrier layer (thickness≤coherence length of a Cooper electron pair) between two superconducting material layers

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentUS12016253B2Quantum chip test structure and fabrication method therefor, and test method and fabrication method for quantum chip

Publication Date: 2024.06.18 ORIGIN QUANTUM COMPUTING TECH (HEFEI) CO LTD

AI summary

Disclosed are a quantum chip test structure and a fabrication method therefor, and a test method and a fabrication method for a quantum chip. The quantum chip test structure includes: a superconducting Josephson junction and a connection structure of the superconducting Josephson junction that are located on a substrate; a first isolation layer located on the connection structure, where a connection window penetrating through the first isolation layer is formed in the first isolation layer; a second isolation layer located on the first isolation layer, where a deposition window is formed in the second isolation layer; and an electrical connection portion located in the connection window and an electrical connection layer located in the deposition window, and the electrical connection layer is configured to implement electrical contact with a test device.