Fabrication of 200 nm period nanomagnet arrays using interference lithography and a negative resist

Magnetic information storage density has increased at the rate of 60% per y ear for the past seven years. There is wide agreement that continuation of this trend beyond the physical limits of the continuous thin-film media cur rently used will likely require a transition to discrete, lithographically defined magnetic pillars, Interference lithography (IL) appears to be the m ost cost-effective means of producing two-dimensional arrays of such pillar s. IL can rapidly expose large areas with relatively simple equipment, with out the need for a mask, and with fine control of the ratio of pillar diame ter to period. We show that negative-tone imaging yields three times the co ntrast of positive-tone imaging for the generation of holes in photoresist, suitable for subsequent deposition or electroplating of magnetic material. We use a negative i-line, chemically-amplified resist (OHKA THMR-iN PS1) t o form 200 nm period arrays of magnetic dots in Co and Ni. Such arrays, wit h a variety of well controlled diameters, are used to study the effect of p article size on magnetic behavior. (C) 1999 American Vacuum Society [S0734- 211X(99)06806-7].