Square patterns formed from the directed self-assembly of block copolymers

Abstract

Since tremendous progress has been made, directed self-assembly (DSA) of block copolymers has been regarded as one of the most promising bottom-up lithography techniques. In particular, DSA has been successfully applied to fabricate large-scale ordered stripes and hexagonal arrays of dots. More importantly, many efforts have been devoted to developing DSA strategies for the preparation of square patterns that are more in line with the needs of lithography in semiconductors. Here, we present a brief overview of recent progress in the DSA strategies for the fabrication of square patterns. Although numerous DSA strategies based on the simple AB diblock copolymer or ABC linear triblock copolymer have been developed, each strategy exhibits more or less disadvantages lying in poor long-range ordering, low density multiplication or difficulty with pattern transfer because of the intrinsic weaknesses in the bulk structures formed by these block copolymers. Very recently, self-consistent field theory studies revealed that a square array of cylinders can be stabilized in various AB-type block copolymers with purposely designed architectures. An efficient DSA strategy using these AB-type block copolymers could be developed for the fabrication of large-scale ordered square patterns in future, and will exhibit promising application prospects.