Fabrication Process for Deep Submicron SQUID Circuits with Three Independent Niobium Layers.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Quantum Technologies

Background:

• Superconducting Quantum Interference Devices (SQUIDs) are crucial for sensitive magnetic field detection.
• Fabricating nanoscale SQUIDs with complex structures presents significant challenges.
• Existing methods often limit circuit density and integration capabilities.

Purpose of the Study:

• To present a novel fabrication technology for nanoscale SQUIDs.
• To enable the creation of more complex and dense superconducting circuits.
• To demonstrate the feasibility of a three-iobium-layer process for SQUID fabrication.

Main Methods:

• Utilized electron-beam lithography, chemical-mechanical polishing, and magnetron sputtering.
• Developed a process for fabricating superconductor-normal metal-superconductor (SNS) Josephson junctions with Nb/HfTi/Nb trilayers.
• Extended the fabrication process to incorporate three independent niobium layers, allowing for superconducting vias.

Main Results:

• Successfully produced direct current SQUIDs with 100-nm lateral dimensions.
• Demonstrated a three-layer niobium fabrication process, enabling superconducting vias without a HfTi barrier.
• Achieved increased potential for circuit density and complexity.

Conclusions:

• The presented fabrication technology is suitable for producing nanoscale SQUIDs.
• The three-layer process significantly enhances the potential for integrated superconducting circuits.
• This method paves the way for next-generation quantum devices with improved functionality.