Orientation and Position Control of Self-Assembled Polymer Pattern for Bit-Patterned Media

Directed self-assembly (DSA) is expected to be a solution for the fabrication process of high-density bit-patterned media. A DSA pattern of polystyrene-b-polydimethylsiloxane diblock copolymer with 20 nm pitch was fabricated on a 2.5 in disk substrate using a postguide. Uniformity of the dot alignment as well as dot-pitch fluctuation and linearity of pseudodot tracks are estimated using image analyses of SEM photographs. Uniformity along the circumferential direction was confirmed. All the SEM images at eight different angles at r=29.4 mm showed single domain. Pitch distribution and linearity error were estimated to be 14% and 7.8%, respectively. Uniformity along the radius direction was estimated with the moiré method. The single-domain region is expected to be 5 mm in width. Margin of the postguide pitch for the single-domain formation is revealed to be more than 15% of the self-assembled dot pitch.