Characterization of pattern transfer in the fabrication of magnetic nanostructure arrays by block copolymer lithography

The authors report the fabrication of large-area antidot arrays using cylinder-forming polystyrene-polyisoprene-polylactide triblock terpolymer templates. 30 nm antidots were generated after removal of the minority polymer component by aqueous degradation, oxygen reactive ion etching, and subsequent Ar ion beam milling to transfer the pattern to an underlying Ni80 Fe20 film. Emphasis was placed on characterization of the pattern transfer, which was tracked using a combination of atomic force microscopy, magnetometry, and magnetotransport. It is demonstrated that variable temperature magnetometry and transport measurements are excellent probes of the progress of the ion milling into underlying magnetic layers.