Effects of lateral straggling of ions on patterned media fabricated by nitrogen ion implantation

Patterned media were fabricated by nitrogen ion implantation and how ion lateral straggling affects the pattern size was analyzed to confirm the feasibility for high-density recording. N-2(+) ions were implanted with ion energies of 6, 10, 14, and 19 keV through an ion-depth-control layer with suitable thicknesses for the ion energies to make the same ion depth profile. The dosage was 1.8 x 10(16) ions/cm(2). The saturation magnetization in the ion-implanted area was decreased from 0.56 to 0.05 T for all the media. Preamble pattern width was obtained by analyzing the readback signal. It was also estimated using calculated ion lateral straggling width and measured mask width. The reduction ratio of the pattern width against the ion energy was almost the same for the signal analysis and calculation results. This indicates that the pattern width was decreased just by the width of the ion lateral straggling. Therefore, high-density small patterns can be fabricated by reducing ion energy and suppressing ion lateral straggling. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676427]