Large-Scale Focused Helium Ion Beam Lithography

Focused ion beam sources have recently been commercialized and are increasingly utilized for applications in nanotechnology. There is a desire to pattern large designs, millimeter in scale, while still achieving sub-nanometer resolution in the smallest features. However, focused helium ion beams are restricted to fields of view of roughly 100 micrometers. Recently, we have developed an automated process for layout designs with feature sizes from sub-nanometer to millimeter scales, using Raith lithography software in a Zeiss Orion Plus helium ion microscope. The technique relies on stitching writefields together and incorporating automated focusing algorithms in the Raith software. This procedure was demonstrated by scaling and automating the process of producing ion-damaged Josephson junctions in arrays in the high-temperature superconducting material YBa ₂ Cu ₃ O _7-δ . We demonstrate that the automated process reduces operator input while maintaining consistency at the smallest resolutions.