A METHOD FOR PREPARING ATOM-PROBE SPECIMENS FOR NANOSCALE COMPOSITIONAL ANALYSIS OF METALLIC THIN-FILMS

A method for preparing atom probe field ion microscope (APFIM) specimens for nano-scale characterization of metallic thin films was developed. Magnetic thin films of Fe-Ta-C and Co-Cr were sputtered on a Cu coated glass substrate. Resist patterns with nearly the same width as the thickness of the film were printed on the film by a photolithography process. The resist coated film was, then, ion milled until the Cu buffer layer appeared. After removing the remaining resist film by acetone, the Cu underlayer was dissolved by a chromic acid solution. The fine rods were picked up on top of tungsten wires with a precision goniometer stage while observing by an optical microscope. These rods were then sharpened to FIM tips with a radius of approximately 10 nm by the pulsed micropolishing technique.