Bias-sputtered Nb for reliable wirings in Josephson circuits

Author

Imamura, T. ; Ohara, S. ; Hasuo, S.

Author_Institution

Fujitsu Lab. Ltd., Atsugi, Japan

Volume

27

Issue

2

fYear

1991

fDate

3/1/1991 12:00:00 AM

Firstpage

3176

Lastpage

3179

Abstract

Bias-sputtered Nb films were applied to wirings in Josephson circuits. Applying bias voltage during sputtering improved Nb step coverage and stability against annealing. Deteriorated superconducting characteristics in films were negligible for bias voltage less than -150 V. The characteristics of contacts formed between two Nb wirings were studied. By using bias-sputtered Nb as the upper wiring, the I _c of the contacts increased 2-10 times. Reduction in contact I_c after annealing was markedly suppressed. The authors verified that the bias-sputtered Nb was feasible in Josephson circuits as reliable wirings, with no compromise of junction characteristics

Keywords

metallisation; niobium; sputtered coatings; superconducting integrated circuits; superconducting junction devices; -150 to -300 V; Josephson circuits; Nb step coverage; bias voltage during sputtering; bias-sputtered Nb; characteristics of contacts; junction characteristics; reliable wirings; stability against annealing; superconducting characteristics; Annealing; Argon; Integrated circuit reliability; Niobium; Sputtering; Superconducting films; Surface morphology; Tensile stress; Voltage; Wiring;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.133886

Filename

133886