Suspended metal mask techniques in Josephson junction fabrication

Journal Article · Tue Jan 01 04:00:00 EST 1985 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.583246· OSTI ID:5993177

Ono, R H; Sauvageau, J E; Jain, A K; Schwartz, D B; Springer, K T; Lukens, J E

We report here two processes for in-situ, self-aligned fabrication of niobium based Josephson tunnel junctions and SNS microbridges in which multiple evaporations at varying angles are made through a suspended metal stencil fabricated by electron beam lithography (EBL). Both techniques have proved superior to earlier all-polymer suspended masks, particularly with e-gun evaporated refractory metals such as niobium. The first process uses a trilevel resist and ion milling to pattern a gold stencil suspended on PMMA. In the second process, an aluminum stencil suspended on polyimide (PI) is patterned by lift-off with an EBL mask written in a PMMA layer on top of the PI. The PI is then undercut using an oxygen plasma etch through the aluminum mask. Reproducible ( +- 20 nm) submicrometer dimensions and good junction characteristics have been achieved using these techniques without the need for difficult-to-control surface cleaning procedures.

• Research Organization: Department of Physics, State University of New York at Stony Brook, Stony Brook, New York 11794
• OSTI ID: 5993177
• Journal Information: J. Vac. Sci. Technol., B; (United States), Journal Name: J. Vac. Sci. Technol., B; (United States) Vol. 3:1; ISSN JVTBD
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
ALUMINIUM
BEAMS
CLEANING
COLLISIONS
ELECTRON BEAMS
ELEMENTS
ESTERS
EVAPORATION
FABRICATION
ION COLLISIONS
JOSEPHSON JUNCTIONS
JUNCTIONS
LEPTON BEAMS
MASKING
METALS
NIOBIUM ALLOYS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PARTICLE BEAMS
PHASE TRANSFORMATIONS
PMMA
POLYACRYLATES
POLYMERS
POLYVINYLS
SUPERCONDUCTING JUNCTIONS
SURFACE CLEANING
SURFACE FINISHING
TUNNEL EFFECT
VACUUM EVAPORATION