Advanced Fabrication Processes for Superconductor Electronics: Current Status and New Developments

Tolpygo, Sergey K.; Bolkhovsky, Vladimir; Rastogi, Ravi; Zarr, Scott; Day, Alexandra; Golden, Evan; Weir, Terence J.; Wynn, Alex; Johnson, L. M.

doi:10.1109/tasc.2019.2904919

Cited by 82 publications

(61 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, several research groups have reported successful demonstrations of large-scale, energy-efficient superconductor digital circuits [8][9][10], which indicates the high robustness, as well as the high energy efficiency, of superconductor logic families. Note that these demonstrations were supported by recent advances in fabrication technology for superconductor integrated circuits [11][12][13].…”

Section: Introductionmentioning

confidence: 82%

Adiabatic Quantum-Flux-Parametron: A Tutorial Review

Takeuchi

Yamae

Ayala

et al. 2022

IEICE Trans. Electron.

View full text Add to dashboard Cite

The adiabatic quantum-flux-parametron (AQFP) is an energy-efficient superconductor logic element based on the quantum flux parametron. AQFP circuits can operate with energy dissipation near the thermodynamic and quantum limits by maximizing the energy efficiency of adiabatic switching. We have established the design methodology for AQFP logic and developed various energy-efficient systems using AQFP logic, such as a low-power microprocessor, reversible computer, single-photon image sensor, and stochastic electronics. We have thus demonstrated the feasibility of the wide application of AQFP logic in future information and communications technology. In this paper, we present a tutorial review on AQFP logic to provide insights into AQFP circuit technology as an introduction to this research field. We describe the historical background, operating principle, design methodology, and recent progress of AQFP logic.

show abstract

Section: Introductionmentioning

confidence: 82%

Adiabatic Quantum-Flux-Parametron: A Tutorial Review

Takeuchi

Yamae

Ayala

et al. 2022

IEICE Trans. Electron.

View full text Add to dashboard Cite

show abstract

“…We briefly discuss the potential for a JJ/MJJ neural network as compared to modern CMOS. JJ/MJJ based neural networks can leverage the development of digital JJ circuits, which are near 106 JJ's per square cm 26,27 . While these densities are no-where near modern CMOS the JJ fabrication process continues to scale and at roughly 106 JJ's per cm2 some smaller scale applications may be within reach.…”

Section: Discussionmentioning

confidence: 99%

Synaptic weighting in single flux quantum neuromorphic computing

Schneider

Donnelly

Haygood

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Josephson junctions act as a natural spiking neuron-like device for neuromorphic computing. By leveraging the advances recently demonstrated in digital single flux quantum (SFQ) circuits and using recently demonstrated magnetic Josephson junction (MJJ) synaptic circuits, there is potential to make rapid progress in SFQ-based neuromorphic computing. Here we demonstrate the basic functionality of a synaptic circuit design that takes advantage of the adjustable critical current demonstrated in MJJs and implement a synaptic weighting element. The devices were fabricated with a restively shunted Nb/AlO x-Al/Nb process that did not include MJJs. Instead, the MJJ functionality was tested by making multiple circuits and varying the critical current, but not the external shunt resistance, of the oxide Josephson junction that represents the MJJ. Experimental measurements and simulations of the fabricated circuits are in good agreement.

show abstract

“…The fabrication process of the first module is very similar to our new process SC1 [24], whereas the second JJ module is identical to the SFQee process developed in [1], [2]. Vias to Nb layers M4, M5, etc., are named, respectively, I4, I5, etc.…”

Section: A Layer Stack and Jc Optionsmentioning

confidence: 99%

“…Our fabrication process for Nb/Al/AlOx/Nb junctions was described in detail in [1]- [3], [24]. We adjusted the Nb deposition process in order to obtain a more uniform stress distribution, primarily between the center and edge of the wafers.…”

Section: B Sis and Sfs Trilayers Fabricationmentioning

confidence: 99%

Planarized Fabrication Process With Two Layers of SIS Josephson Junctions and Integration of SIS and SFS <italic>π</italic>-Junctions

Tolpygo

Bolkhovsky

Rastogi

et al. 2019

IEEE Trans. Appl. Supercond.

Self Cite

View full text Add to dashboard Cite

We present our new fabrication Process for Superconductor Electronics (PSE2) that integrates two (2) layers of Josephson junctions (JJs) in a fully planarized multilayer process on 200-mm wafers. The two junction layers can be, e.g., conventional Superconductor-Insulator-Superconductor (SIS) Nb/Al/AlOx/Nb junctions with the same or different Josephson critical current densities, Jc. The process also allows integration of high-Jc Superconductor-Ferromagnet-Superconductor (SFS) or SFS'S JJs on the first junction layer with Nb/Al/AlOx/Nb trilayer junctions on the second JJ layer, or vice versa. In the present node, the SFS trilayer, Nb/Ni/Nb is placed below the standard SIS trilayer and separated by one niobium wiring layer. The main purpose of integrating the SFS and SIS junction layers is to provide compact π-phase shifters in logic cells of superconductor digital circuits and random access memories, and thereby increase the integration scale and functional density of superconductor electronics. The current node of the two-junction-layer process has six planarized niobium layers, two layers of resistors, and 350-nm minimum feature size. The target critical current densities for the SIS JJs are 100 μA/μm 2 and 200 μA/μm 2 . We present the salient features of the new process, fabrication details, and characterization results on two layers of JJs integrated into one process, both for the conventional and πjunctions.

show abstract

Advanced Fabrication Processes for Superconductor Electronics: Current Status and New Developments

Cited by 82 publications

References 39 publications

Adiabatic Quantum-Flux-Parametron: A Tutorial Review

Adiabatic Quantum-Flux-Parametron: A Tutorial Review

Synaptic weighting in single flux quantum neuromorphic computing

Planarized Fabrication Process With Two Layers of SIS Josephson Junctions and Integration of SIS and SFS <italic>π</italic>-Junctions

Contact Info

Product

Resources

About