Thermal stability of Pb-alloy Josephson junction electrode materials. II. Effects of SiO coating on Pb-In-Au base electrode

Journal Article · Sun Mar 01 04:00:00 EST 1981 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.329758· OSTI ID:6570991

Murakami, M

The preceding paper pertains to studies which were carried out for Pb-In-Au films without overlying SiO layers. Because use is made of configurations in Josephson junction integrated circuits presently under investigation in which Pb-In-Au base-electrode films are coated by overlying layers of SiO, a study was undertaken of the effects of such layers on the strain behavior of Pb-In-Au films using an x-ray diffraction technique. Pb-12 wt. % In-4 wt. % Au films were prepared at 298 or 77 K to obtain large or fine grains, respectively, and then thermally cycled between 300 and 4.2 K and between 300 and 350 K. In large-grained Pb-In-Au films, the strain relaxation, upon thermal cycling, by dislocation glide or by grain-boundary diffusion creep, was observed to be significantly inhibited by overlying SiO layers. However, in fine-grained films, that was not observed. For junctions in which the tunnel oxide is formed within an opening in an overlying SiO layer, it is believed, e.g., that upon heating, a compressive strain gradient develops in the large-grained base-electrode films between the junction area and its surrounding, leading to base-electrode deformation inside the opening that could rupture the tunnel oxide. This study indicates that the strain gradient should be reduced by reducing the average grain size of the base-electrode films. These results agree well with the previous experimental results in which no hillocks were detected by scanning electron microscopy inside similar SiO-layer openings above fine-grained Pb-In-Au films during repeated thermal cycling between 300 and 4.2 K or upon heating from 300 to 343 K.

• Research Organization: IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598
• OSTI ID: 6570991
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 52:3; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
CHALCOGENIDES
COATINGS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DATA
DIFFRACTION
ELECTRODES
ELECTRONIC CIRCUITS
ELEMENTS
FILMS
GOLD
GRAIN SIZE
INDIUM
INFORMATION
INTEGRATED CIRCUITS
JOSEPHSON JUNCTIONS
JUNCTIONS
LAYERS
LEAD ALLOYS
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
MICROELECTRONIC CIRCUITS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SILICON COMPOUNDS
SILICON OXIDES
SIZE
STABILITY
STRAINS
SUPERCONDUCTING JUNCTIONS
TRANSITION ELEMENTS
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE
X-RAY DIFFRACTION