Performance of DC SQUIDs fabricated on 4-inch silicon wafer

Author

Shimizu, N. ; Chiba, N. ; Yabe, S. ; Ishikawa, T. ; Chinone, K. ; Kiryu, S.

Author_Institution

Seiko Instrum. Inc., Chiba, Japan

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

1828

Lastpage

1831

Abstract

A Nb/AlO/sub x//Nb Josephson process has been developed to fabricate DC superconducting quantum interference devices (SQUIDs) for biomagnetic measurements on 4-in silicon wafers. The purpose of the process is to fabricate high-quality junctions and to keep the quality uniform over a silicon wafer. All the films were deposited using magnetron sputtering. The components of the SQUID, except the junctions, were formed by taper etching to improve the step coverage. The uniformity of the SQUID characteristics (critical current, modulation depth, and mutual inductance between SQUID and modulation coil) was measured, and an excellent value of less than +or-5% was obtained. Three different configurations of SQUIDs, single washer (SW), double washer series (DWS), double washer parallel (DWP) have been fabricated with the same characteristics. The SW (single washer) had a white noise level of 6.3*10/sup -6/ Phi /sub 0// square root Hz, lower than those of DWS and DWP. 1/f crossover frequencies were below 1 Hz.<>

Keywords

SQUIDs; aluminium compounds; biological techniques and instruments; biomagnetism; critical currents; electric sensing devices; electron device noise; etching; inductance; magnetic field measurement; niobium; sputter deposition; superconducting thin films; white noise; 1/f crossover frequencies; 4 inch; DC superconducting quantum interference devices; Josephson process; Nb-AlO/sub x/-Nb; Si wafer; biomagnetic measurements; critical current; double washer parallel; double washer series; high-quality junctions; magnetron sputtering; modulation depth; mutual inductance; single washer; step coverage; taper etching; white noise level; Biomagnetics; Interference; Josephson junctions; Niobium; SQUIDs; Silicon; Sputtering; Superconducting devices; Superconducting films; Superconducting magnets;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233326

Filename

233326