Design Rules for Resistors, Capacitors and Inductors Fabricated From Single Layer Y-Ba-Cu-O Thin Films With Focused Helium Ion Beam Irradiation

Abstract

Yttrium barium copper oxide (YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-<inline-formula><tex-math notation="LaTeX">$\delta$</tex-math></inline-formula></sub> or YBCO) Josephson junctions fabricated using focused helium gas field ion sources show great promise for high transition temperature superconducting electronics. A unique feature of this technology is that it can also be utilized for the fabrication of resistors, capacitors and inductors in the same material and process step. The key to this method is that the electrical resistivity of high critical temperature superconductors is very sensitive to ion irradiation. The ions introduce disorder into the material which causes it to undergo a metal-to-insulator transition. By carefully controlling the position of the beam and ion dose delivered to the material, insulating pathways and reduced critical temperature metallic regions can be fabricated to construct the aforementioned passive components. We have prepared this manuscript to serve as a guide for circuit designers utilizing this process. We discuss the capabilities and limitations of helium ion beam lithographic patterning of YBCO and estimate the practical ranges of the values that can be obtained for resistors, capacitors and inductors in single layer thin films. Estimates are provided for two processes: one with the highest resolution with the smallest beam diameter (0.5 nm) and another based on the highest source current (100 pA) for fastest write time.