Nanofabrication by Masked Ion Damage

RS Speaks, WE Booij, N Peng(*), MG Blamire
Materials Science Dept, University of Cambridge, Cambridge, UK, CB2 3QZ
*SCRIBA, University of Surrey, Guildford, UK, GU2 5XH

We report the development of reusable stencil masks and direct metal masks
for production of resistors and junction in high temperature
superconductors by light ion implantation.  The work has potential to
produce a technology suitable for rapid fabrication of large scale arrays
of HTS circuit components.  The stencil masks were created from Si/SiN
wafers and the metal sandwich masks were created by direct deposition onto
superconducting films.  The masks were then patterned on a focused ion
beam microscope using 30KeV Ga ions and 70 to 150pA aperture.  Line widths
of about 100nm were obtained with enhanced etching using Iodine gas to
reduce the amount of redeposition from the cuts in the sample.  The samples
were then irradiated with 30 to 50KeV of H2+ ions.  The uniformity of the
created resistors was assessed by resistance versus temperature profiles,
and the junction quality was determined form the IV curves.

This work was funded by grants from the National Science Foundation and
EPSRC.