Ga Lithography in Sputtered Niobium for Superconductive Micro and Nanowires.

Journal Article · 18 August 2014 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.4893446 · OSTI ID:1182981

Henry, Michael David ^[1]; Lewis, Rupert M. ^[1]; Wolfley, Steven L. ^[1]; Monson, Todd C. ^[1]

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1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

This work demonstrates the use of FIB implanted Ga as a lithographic mask for plasma etching of Nb films. Using a highly collimated Ga beam of a FIB, Nb is implanted 12 nm deep with a 14 nm thick Ga layer providing etch selectivity better than 15:1 with fluorine based etch chemistry. Implanted square test patterns, both 10 um by and 10 um and 100 um by 100 um, demonstrate that doses above than 7.5 x 1015 cm-2 at 30 kV provide adequate mask protection for a 205 nm thick, sputtered Nb film. The resolution of this dry lithographic technique is demonstrated by fabrication of nanowires 75 nm wide by 10 um long connected to 50 um wide contact pads. The residual resistance ratio of patterned Nb films was 3. The superconducting transition temperature, Tc =7.7 K, was measured using MPMS. This nanoscale, dry lithographic technique was extended to sputtered TiN and Ta here and could be used on other fluorine etched superconductors such as NbN, NbSi, and NbTi.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1182981
• Report Number(s): SAND-2014-15504J; 533692
• Journal Information: Applied Physics Letters, Vol. 105, Issue 7; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English