Josephson Junction Qubit Fabrication via Thermal Hardening
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Solution Overview
Problem
Current methods for fabricating quantum bits (qubits) are limited by the need for low-temperature processing, which hinders mass production and reproducibility, and existing techniques like electron beam lithography are slow and inefficient for large-scale production.
Innovation Solution
A method involving the formation of a Josephson junction trilayer with a thermal hardening process to control diffusion, allowing for processing at standard silicon temperatures and reducing the need for special low-temperature handling, thereby enabling more efficient and reliable qubit production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-temperature processing is used to fabricate Josephson junction qubits, then the delicate metal-oxide-metal junctions are protected from diffusion and chemical reactions, but mass production becomes difficult and production costs increase
Solution Approach 1:
The patent applies a preliminary thermal hardening anneal process to the dielectric layer before forming the Josephson junctions. This pre-treatment stabilizes the dielectric layer's crystal structure and reduces its susceptibility to diffusion during subsequent high-temperature processing steps, enabling standard semiconductor fabrication processes to be used without compromising junction integrity
Solution Approach 2:
The patent changes the thermal parameters of the dielectric layer by subjecting it to controlled annealing at specific temperatures (e.g., 400-800°C) for defined time periods. This parameter modification transforms the dielectric material's properties, making it resistant to further thermal diffusion while allowing the use of standard high-temperature semiconductor processing equipment
2Manufacturing precision
If electron beam lithography is used to fabricate qubits, then small feature sizes are achieved, but production time increases significantly
Solution Approach 1:
The patent makes the qubit fabrication process compatible with standard semiconductor manufacturing equipment and processes, including conventional lithography techniques. This universality allows the use of high-speed, high-volume fabrication tools originally designed for classical semiconductors, dramatically increasing production throughput while maintaining the ability to fabricate small feature sizes through proven lithographic methods
3Loss of time
If small samples are used for qubit fabrication, then production time is reduced, but economies of scale cannot be exploited
Solution Approach 1:
The patent enables the fabrication of large arrays of identical qubit circuits on single large substrates using standard semiconductor wafer processing. Once the process parameters are established, thousands of qubit devices can be simultaneously fabricated on a single wafer, copying the same circuit design across the entire substrate area, thereby achieving both high volume production and cost efficiency
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 reduces production costs, cycle time, and increases yield and uniformity, making it possible to use standard semiconductor processing methods and achieving more reliable qubits.
Implementation Method 1
performing a thermal hardening process on the JJ trilayer to control diffusion of the dielectric layer into the bottom superconductor material layer and the top superconductor material layer
Implementation Method 2
annealing the JJ trilayer in an inert environment at a temperature between about 150° C. to about 400° C. for a time period between about 15 minute to about 120 minutes to control diffusion
Data Source
AI summary
A Josephson junction (JJ) quantum bit (qubits) arranged on a substrate is provided. In one embodiment, each qubit comprises a dielectric layer, a superconductor base layer portion underlying the dielectric layer and a first dielectric diffused region adjacent a dielectric layer/superconductor base layer portion junction. The qubit further comprise a superconductor mesa layer portion overlying the dielectric layer and having a second dielectric diffused region adjacent a dielectric layer/superconductor mesa layer portion junction, the first and second dielectric diffused regions mitigating further diffusion from other semiconductor processes on the plurality of qubits.