New Nb multi-layer fabrication process for large-scale SFQ circuits

Nagasawa, Shuichi; Satoh, T.; Hinode, K.; Kitagawa, Yoshihiro; Hidaka, Mutsuo; Akaike, Hiroyuki; Fujimaki, Akira; Takagi, Kazumasa; Takagi, Naofumi; Yoshikawa, Nobuyuki

doi:10.1016/j.physc.2009.05.219

Cited by 66 publications

(41 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The device structures in the advanced process have changed slightly as fabrication technology has progressed [3]- [8]. We previously developed the Nb 10-layer fabrication process [8].…”

Section: Device Structure Of Advanced Processmentioning

confidence: 99%

“…The standard process involves using up to four Nb layers and Josephson junctions (JJ) with a critical current density of 2.5 kA/cm 2 [1], [2]. On the other hand, the advanced process uses six to ten Nb layers and JJs with a critical current density of 10 kA/cm 2 [3]- [8]. Although the advanced process has disadvantages in a longer turn-around time of the fabrication and a larger amount of the photomask costs, it enables SFQ circuits to operate at a higher frequency and to be integrated at a higher density than the standard process.…”

Section: Introductionmentioning

confidence: 99%

“…It also requires planarization technology to construct a multi-layer structure having more than six Nb layers and higher reliability than the standard process. To construct the multi-layer structure, we have developed caldera planarization technology [3], [4] and complemented caldera planarization technology [7], [8]. To improve the reliability of the advanced Manuscript received July 17, 2013.…”

Section: Introductionmentioning

confidence: 99%

“…a) E-mail: s-nagasawa@aist.go.jp DOI: 10.1587/transele.E97.C.132 fabrication process, we have designed diagnostic chips and shift register (SR) chips and have been evaluating them over a long term of time [5], [8], [19]- [21].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Nb 9-Layer Fabrication Process for Superconducting Large-Scale SFQ Circuits and Its Process Evaluation

Nagasawa¹,

Hinode²,

Satoh³

et al. 2014

IEICE Trans. Electron.

139

View full text Add to dashboard Cite

SUMMARYWe describe the recent progress on a Nb nine-layer fabrication process for large-scale single flux quantum (SFQ) circuits. A device fabricated in this process is composed of an active layer including Josephson junctions (JJ) at the top, passive transmission line (PTL) layers in the middle, and a DC power layer at the bottom. We describe the process conditions and the fabrication equipment. We use both diagnostic chips and shift register (SR) chips to improve the fabrication process. The diagnostic chip was designed to evaluate the characteristics of basic elements such as junctions, contacts, resisters, and wiring, in addition to their defect evaluations. The SR chip was designed to evaluate defects depending on the size of the SFQ circuits. The results of a long-term evaluation of the diagnostic and SR chips showed that there was fairly good correlation between the defects of the diagnostic chips and yields of the SRs. We could obtain a yield of 100% for SRs including 70,000 JJs. These results show that considerable progress has been made in reducing the number of defects and improving reliability.

show abstract

“…The device structures in the advanced process have changed slightly as fabrication technology has progressed [3]- [8]. We previously developed the Nb 10-layer fabrication process [8].…”

Section: Device Structure Of Advanced Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nb 9-Layer Fabrication Process for Superconducting Large-Scale SFQ Circuits and Its Process Evaluation

Nagasawa¹,

Hinode²,

Satoh³

et al. 2014

IEICE Trans. Electron.

139

View full text Add to dashboard Cite

show abstract

“…Thus, we can obtain the scaling law that the miniaturization leads to higher integration and higher operating frequency. [11] and that with the ISTEC 10-kA/cm 2 technology [12], respectively. As indicated by the scaling law, the clock period for the DFF with the 10-kA/cm 2 technology becomes almost half compared to the DFF made with the 2.5-kA/cm 2 technology.…”

Section: Rapid Single Flux Quantum Circuitsmentioning

confidence: 99%

Advancement of superconductor digital electronics

Fujimaki

2012

IEICE Electron. Express

View full text Add to dashboard Cite

Advancement of superconductor digital electronics, especially Rapid Single Flux Quantum (RSFQ) logic circuit is described. Ultra short pulse of a voltage generated across a Josephson junction and release from charging/discharging process for signal transmission in RSFQ circuits enable us to reduce power consumption and gate delay. The power-delay products (PDPs) of RSFQ integrated circuits (ICs) are 4 or 5 orders of magnitude smaller than those of semiconductor ICs. The fabrication process technology and the related designing technology have been advanced, and RSFQ ICs have been applied to software-defined radio receivers, superconductor detector array systems, and supercomputers. Recently, several kinds of energy-efficient single flux quantum circuit have been proposed to obtain further advantage to semiconductor devices. The PDPs of these circuits become at least 1 order smaller than those of conventional RSFQ circuits. Keywords: single flux quantum, superconductor, energy efficiency, high-speed, power-delay product Classification: Superconducting electronics References

show abstract

Superconducting Electronics

Fourie

2014

Wiley Encyclopedia of Electrical and Electronics Engineering

View full text Add to dashboard Cite

An overview of the state of superconducting electronics is presented, starting with Josephson junction and dc SQUID as active devices. Analogue electronics for detectors, mixers, voltage standards and ultra‐sensitive magnetometers are discussed, as well as their application to fields ranging from radio astronomy through metrology to stand‐off security imaging. An overview of the fundamental operating principles of the most successful superconducting logic family, RSFQ, is given, followed by a critical look at the main problems facing large‐scale RSFQ integrated circuits. Contemporary methods to reduce static power consumption and magnetic fields from bias currents are highlighted, with a quick look at energy‐efficient SFQ (eSFQ), current recycling and on‐chip shielding in advanced fabrication processes as prime examples of such methods. Integrated circuit fabrication, cryocooling and other digital logic families are also discussed. We conclude with a look at energy‐efficient supercomputing and quantum computing as near‐future applications of superconducting electronics.

show abstract

New Nb multi-layer fabrication process for large-scale SFQ circuits

Cited by 66 publications

References 15 publications

Nb 9-Layer Fabrication Process for Superconducting Large-Scale SFQ Circuits and Its Process Evaluation

Nb 9-Layer Fabrication Process for Superconducting Large-Scale SFQ Circuits and Its Process Evaluation

Advancement of superconductor digital electronics

Superconducting Electronics

Contact Info

Product

Resources

About