5 Tdot/inch2 bit-patterned media fabricated by directed self-assembling polymer mask

FePt bit-patterned media (BPM) was fabricated with a self-assembled polymer mask with 12 nm pitch (equivalent to 5 Tdot/inch²). A 3.2 nm FePt film with high c axis crystal orientation was prepared for the magnetic recording layer. Solvent vapor annealing was applied for uniform directed self-assembling of PS (polystyrene) - PDMS (polydimethylsiloxane) diblock copolymer. Pattern transfer from a polymer mask to FePt layer was achieved by employing a C hard mask. In spite of excellent magnetic characteristics of FePt layer, the fabricated FePt BPM showed small coercivity (Hc) of 6 kOe and large switching field distribution (SFD) of 21%. These results are due to the etching damage of FePt dots. Disordering of FePt L₁₀ phase by the etching damage reduced magnetic anisotropy energy (Ku).