Development of Multi-Layer Fabrication Process for SFQ Large Scale Integrated Digital Circuits

We have developed a fabrication technology for superconducting integrated circuits with Nb-based Josephson junctions. The standard fabrication process with 10 mask levels includes 3 Nb superconducting layers and a Mo resistor layer. The influence of deposition parameters on film stress, electrical p...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2021-08, Vol.31 (5), p.1-4
Main Authors: Ying, Liliang, Zhang, Xue, Niu, Minghui, Ren, Jie, Peng, Wei, Maezawa, Masaaki, Wang, Zhen
Format: Article
Language:English
Subjects:
Aluminum
Critical current density
Deposition
Digital electronics
Electrical junctions
Electrical properties
Fabrication
Integrated circuits
Josephson device fabrication
Josephson junctions
Large scale integration
Molybdenum
Multilayers
Niobium
Resistors
SFQ circuits
Silicon dioxide
Superconducting electronics fabrication
Superconducting integrated circuits
Superconducting LSI
Superconducting materials
Superconductivity
Surface roughness
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Summary:We have developed a fabrication technology for superconducting integrated circuits with Nb-based Josephson junctions. The standard fabrication process with 10 mask levels includes 3 Nb superconducting layers and a Mo resistor layer. The influence of deposition parameters on film stress, electrical properties, and surface roughness were studied systematically. High quality Nb, Al, Mo, and SiO 2 films were successfully deposited for the subsequent fabrication of circuits. The circuit fabrication started with the fabrication of Mo resistors with a target sheet resistance R sh of 2 Ω, followed by the deposition of Nb/Al-AlO x /Nb trilayer Josephson-junction. The target critical current density J c was set at 6 kA/cm 2 . Small-scale circuits such as our standard library cells have been successfully fabricated and tested, confirming the capability of our fabrication technology for superconducting integrated circuits.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2021.3065277