Three-dimensional adiabatic quantum-flux-parametron fabricated using a double-active-layered niobium process

Ando, Tetsu; Nagasawa, Shuichi; Takeuchi, Naoki; Tsuji, Naoki; China, Fumihiro; Hidaka, Mutsuo; Yamanashi, Yuki; Yoshikawa, Nobuyuki

doi:10.1088/1361-6668/aa6ef4

Cited by 30 publications

(16 citation statements)

References 23 publications

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“…The dimension of the RQFP cell is 180 μm × 145 μm, which is only 36% of that of the original design (270 μm × 270 μm) [10]. Further miniaturization might be possible by using a three-dimensional fabrication process [35]. I x1 and I x2 are the excitation currents, I ina through I inc are the input currents, which are applied to the RQFP cell through BUF chains, and V outx through V outz are the output voltages, which are generated by using the dc superconducting quantum interference devices (dc-SQUIDs) coupled to AQFPs.…”

Section: Methodsmentioning

confidence: 99%

Recent Progress on Reversible Quantum-Flux-Parametron for Superconductor Reversible Computing

Takeuchi

Yamanashi

Yoshikawa

2018

IEICE Trans. Electron.

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SUMMARYWe have been investigating reversible quantum-fluxparametron (RQFP), which is a reversible logic gate using adiabatic quantum-flux-parametron (AQFP), toward realizing superconductor reversible computing. In this paper, we review the recent progress of RQFP. Followed by a brief explanation on AQFP, we first review the difference between irreversible logic gates and RQFP in light of time evolution and energy dissipation, based on our previous studies. Numerical calculation results reveal that the logic state of RQFP can be changed quasi-statically and adiabatically, or thermodynamically reversibly, and that the energy dissipation required for RQFP to perform a logic operation can be arbitrarily reduced. Lastly, we show recent experimental results of an RQFP cell, which was newly designed for the latest cell library. We observed the wide operation margins of more than 4.7 dB with respect to excitation currents. key words: reversible computing, adiabatic logic, QFP

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Section: Methodsmentioning

confidence: 99%

Recent Progress on Reversible Quantum-Flux-Parametron for Superconductor Reversible Computing

Takeuchi

Yamanashi

Yoshikawa

2018

IEICE Trans. Electron.

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“…All layers in our process are fully planarized. This allowed us successfully fabricate two fully independent layers of Josephson junctions, similar to the double-JJ-layer process demonstrated in [51]. Availability of multiple junction layers should enable increasing the integration scale of superconductor electronic circuits in a 3D manner.…”

Section: A Mo2n Kinetic Inductor Layer Placementmentioning

confidence: 96%

Superconductor Electronics Fabrication Process with MoNx Kinetic Inductors and Self-Shunted Josephson Junctions

Tolpygo

Bolkhovsky

Oates

et al. 2018

IEEE Trans. Appl. Supercond.

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Recent progress in superconductor electronics fabrication has enabled single-flux-quantum (SFQ) digital circuits with close to one million Josephson junctions (JJs) on 1-cm 2 chips. Increasing the integration scale further is challenging because of the large area of SFQ logic cells, mainly determined by the area of resistively shunted Nb/AlOx-Al/Nb JJs and geometrical inductors utilizing multiple layers of Nb. To overcome these challenges, we are developing a fabrication process with self-shunted high-Jc JJs and compact thin-film MoNx kinetic inductors instead of geometrical inductors. We present fabrication details and properties of MoNx films with a wide range of Tc, including residual stress, electrical resistivity, critical current, and magnetic field penetration depth λ0. As kinetic inductors, we implemented Mo2N films with Tc about 8 K, λ0 about 0.51 μm, and inductance adjustable in the range from 2 to 8 pH/sq. We also present data on fabrication and electrical characterization of Nb-based self-shunted JJs with AlOx tunnel barriers and Jc = 0.6 mA/μm 2 , and with 10-nm thick Si1-xNbx barriers, with x from 0.03 to 0.15, fabricated on 200-mm wafers by cosputtering. We demonstrate that the electron transport mechanism in Si1-xNbx barriers at x < 0.08 is inelastic resonant tunneling via chains of multiple localized states. At larger x, their Josephson characteristics are strongly dependent on x and residual stress in Nb electrodes, and in general are inferior to AlOx tunnel barriers.

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“…Considering the superconductor fabrication is still at an early development stage, the integration density is about 4× to 26× lower when comparing to the TSMC 40 nm CMOS technology. In the future, these numbers can be further reduced by introducing multi-layer techniques 29 and transformer-free AQFP technique 30 .…”

Section: Resultsmentioning

confidence: 99%

Adiabatic Quantum-Flux-Parametron: Towards Building Extremely Energy-Efficient Circuits and Systems

Chen

Cai

Wang

et al. 2019

Sci Rep

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Adiabatic Quantum-Flux-Parametron (AQFP) logic is an adiabatic superconductor logic family that has been proposed as a future technology towards building extremely energy-efficient computing systems. In AQFP logic, dynamic energy dissipation can be drastically reduced due to the adiabatic switching operations using AC excitation currents, which serve as both clock signals and power supplies. As a result, AQFP could overcome the power/energy dissipation limitation in conventional superconductor logic families such as rapid-single-flux-quantum (RSFQ). Simulation and experimental results show that AQFP logic can achieve an energy-delay-product (EDP) near quantum limit using practical circuit parameters and available fabrication processes. To shed some light on the design automation and guidelines of AQFP circuits, in this paper we present an automatic synthesis framework for AQFP and perform synthesis on 18 circuits, including 11 ISCAS-85 circuit benchmarks, 6 deep-learning accelerator components, and a 32-bit RISC-V ALU, based on our developed standard cell library of AQFP technology. Synthesis results demonstrate the significant advantage of AQFP technology. We forecast 9,313×, 25,242× and 48,466× energy-per-operation advantage, compared to the synthesis results of TSMC (Taiwan Semiconductor Manufacturing Company) 12 nm fin field-effect transistor (FinFET), 28 nm and 40 nm complementary metal-oxide-semiconductor (CMOS) technology nodes, respectively.

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Three-dimensional adiabatic quantum-flux-parametron fabricated using a double-active-layered niobium process

Cited by 30 publications

References 23 publications

Recent Progress on Reversible Quantum-Flux-Parametron for Superconductor Reversible Computing

Recent Progress on Reversible Quantum-Flux-Parametron for Superconductor Reversible Computing

Superconductor Electronics Fabrication Process with MoNx Kinetic Inductors and Self-Shunted Josephson Junctions

Adiabatic Quantum-Flux-Parametron: Towards Building Extremely Energy-Efficient Circuits and Systems

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