Side-wall spacer passivated sub-μm Josephson junction fabrication process

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Abstract

We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a sidewall-passivating spacer structure (SWAPS) which is shaped for smooth crossline contacting and low parasitic capacitance. The SWAPS structure enables formation of junctions with dimensions at or below the lithography-limited linewidth. An additional benefit is avoiding the excessive use of amorphous dielectric materials which is favorable in sub-Kelvin microwave applications often plagued by nonlinear and lossy dielectrics. We apply the structure to niobium trilayer junctions, and provide characterization results yielding evidence on wafer-scale scalability, and critical current density tuning in the range of 0.1-3.0 kA cm-2. We discuss the applicability of the junction process in the context of different applications, such as SQUID magnetometers and Josephson parametric amplifiers.

Original languageEnglish
Article number125016
Number of pages6
JournalSuperconductor Science and Technology
Volume30
Issue number12
DOIs
Publication statusPublished - 16 Nov 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Josephson junctions
spacers
Lithography
Niobium
Parametric amplifiers
Fabrication
fabrication
Tunnel junctions
SQUIDs
Magnetometers
lithography
Linewidth
Scalability
Capacitance
Tuning
Microwaves
parametric amplifiers
tunnel junctions
niobium
magnetometers

Keywords

  • Josephson junction
  • Josephson parametric amplifier
  • magnetometer
  • spacer
  • trilayer
  • tunnel junction

Cite this

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title = "Side-wall spacer passivated sub-μm Josephson junction fabrication process",
abstract = "We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a sidewall-passivating spacer structure (SWAPS) which is shaped for smooth crossline contacting and low parasitic capacitance. The SWAPS structure enables formation of junctions with dimensions at or below the lithography-limited linewidth. An additional benefit is avoiding the excessive use of amorphous dielectric materials which is favorable in sub-Kelvin microwave applications often plagued by nonlinear and lossy dielectrics. We apply the structure to niobium trilayer junctions, and provide characterization results yielding evidence on wafer-scale scalability, and critical current density tuning in the range of 0.1-3.0 kA cm-2. We discuss the applicability of the junction process in the context of different applications, such as SQUID magnetometers and Josephson parametric amplifiers.",
keywords = "Josephson junction, Josephson parametric amplifier, magnetometer, spacer, trilayer, tunnel junction",
author = "Leif Gr{\"o}nberg and Mikko Kiviranta and Visa Vesterinen and Janne Lehtinen and Slawomir Simbierowicz and Juho Luomahaara and Mika Prunnila and Juha Hassel",
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TY - JOUR

T1 - Side-wall spacer passivated sub-μm Josephson junction fabrication process

AU - Grönberg, Leif

AU - Kiviranta, Mikko

AU - Vesterinen, Visa

AU - Lehtinen, Janne

AU - Simbierowicz, Slawomir

AU - Luomahaara, Juho

AU - Prunnila, Mika

AU - Hassel, Juha

PY - 2017/11/16

Y1 - 2017/11/16

N2 - We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a sidewall-passivating spacer structure (SWAPS) which is shaped for smooth crossline contacting and low parasitic capacitance. The SWAPS structure enables formation of junctions with dimensions at or below the lithography-limited linewidth. An additional benefit is avoiding the excessive use of amorphous dielectric materials which is favorable in sub-Kelvin microwave applications often plagued by nonlinear and lossy dielectrics. We apply the structure to niobium trilayer junctions, and provide characterization results yielding evidence on wafer-scale scalability, and critical current density tuning in the range of 0.1-3.0 kA cm-2. We discuss the applicability of the junction process in the context of different applications, such as SQUID magnetometers and Josephson parametric amplifiers.

AB - We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a sidewall-passivating spacer structure (SWAPS) which is shaped for smooth crossline contacting and low parasitic capacitance. The SWAPS structure enables formation of junctions with dimensions at or below the lithography-limited linewidth. An additional benefit is avoiding the excessive use of amorphous dielectric materials which is favorable in sub-Kelvin microwave applications often plagued by nonlinear and lossy dielectrics. We apply the structure to niobium trilayer junctions, and provide characterization results yielding evidence on wafer-scale scalability, and critical current density tuning in the range of 0.1-3.0 kA cm-2. We discuss the applicability of the junction process in the context of different applications, such as SQUID magnetometers and Josephson parametric amplifiers.

KW - Josephson junction

KW - Josephson parametric amplifier

KW - magnetometer

KW - spacer

KW - trilayer

KW - tunnel junction

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U2 - 10.1088/1361-6668/aa9411

DO - 10.1088/1361-6668/aa9411

M3 - Article

VL - 30

JO - Superconductor Science and Technology

JF - Superconductor Science and Technology

SN - 0953-2048

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M1 - 125016

ER -