MAGNETIC PROPERTIES OF SPUTTERED COBALT FILMS ON X-RAY LITHOGRAPHIC SUBSTRATES

Arrays of 11.2-16.6 m holes were patterned on 50 m thick SU-8 photoresist layers by using synchrotron X-ray lithography. After the resist development, the chemically stable and mechanically hardened SU-8 templates with varying hole sizes were used as substrates for RF sputtering of 1.5 m-thick cobalt (Co). By comparing hysteresis loops from inplane and out-of-plane magnetisation, the Co film on patterned substrate with average hole size of 16.6 m was more isotropic than in the case of 15.3 and 11.2 m. Both magnetic squareness and coercive field were at the minimum when the holes were smallest. After the removal of Co on SU-8 surfaces, the remaining Co deposits in the holes exhibited smaller squareness and anisotropy. On the other hand, the enhanced coercive field was increased with a reduction in diameter of patterned holes