The improvement in areal density in hard disk drives using conventional multigrain media is currently bound by the superparamagnetic limit [1]. Bit patterned media can circumvent this limitation by creating isolated magnetic islands separated by a nonmagnetic material. Nanoimprint lithography is an attractive solution for producing bit patterned media if a template can be created with sub-25 nm features [2]. Resolution limits in optical lithography and the prohibitive cost of electron beam lithography due to slow throughput [3] necessitate a new template patterning process. The self-assembly of diblock copolymers into well-defined structures [4] on the order of 5-100 nm produces features on the length scale required for production of bit patterned media. This is most efficiently accomplished by using block copolymers to produce templates for imprint lithography [5]. With the availability of the proper template, imprint lithography can be employed to produce bit-patterned media efficiently. Previous research has targeted block copolymers that produce hexagonally packed cylindrical morphology with selective silicon incorporation into one block for etch resistance [6] through post-polymerization SiO2 growth [7], silica deposition using supercritical CO2 [8], and silicon-containing ferrocenyl monomers [9]. What is needed is a method to create an imprint template with sub-100 nm features with the desired structural alignment of nanostructures that can be etched with the good oxygen etch contrast that silicon provides.
USPTO Backgrounds
USPTO Backgrounds