Investigation of cross-linking poly(methyl methacrylate) as a guiding material in block copolymer directed self-assembly

Directed self-assembly (DSA) of block copolymers (BCP) is attracting a growing amount of interest as a technique to expand traditional lithography beyond its current limits. It has recently been demonstrated that chemoepitaxy can be used to successfully direct BCP assembly to form large arrays of high-density features. The imec DSA LiNe flow uses lithography and trim-etch to produce a "prepattern" of cross-linked polystyrene (PS) stripes, which in turn guide the formation of assembled BCP structures. The entire process is predicated on the preferential interaction of the respective BCP domains with particular regions of the underlying prepattern. The use of polystyrene as the guiding material is not uniquely required, however, and in fact may not even be preferable. This study investigates an alternate chemistry - crosslinked poly(methyl methacrylate), X-PMMA, - as the underlying polymer mat, providing a route to higher auto-affinity and therefore a stronger guiding ability. In addition to the advantages of the chemistry under investigation, this study explores the broader theme of extending BCP DSA to other materials.