Impact of Materials Selection on Graphoepitaxial Directed Self-Assembly for Line-Space Patterning

Directed self-assembly (DSA) of block copolymers (BCPs) is a promising technology for advanced patterning at future technology nodes, but significant hurdles remain for commercial implementation. While chemoepitaxy processes employing poly(styrene-block-methyl methacrylate) (PS-PMMA) are most widely studied for DSA line/space patterning, graphoepitaxy processes using more strongly segregated "high-chi" block copolymers have recently shown a lot of promise, with lower defectivity and line-width roughness (LWR) than comparative chemoepitaxy processes. This paper reports on some of the design considerations for optimizing line/space patterning with these materials. We have found that brush and block copolymer selection are critical to achieve high quality DSA. For example, brush thickness must be optimized to achieve matching space critical dimensions, and brush surface energy impacts kinetics of assembly. The chi parameter of the block copolymer should be optimized to balance LWR, kinetics of assembly, and process window. Glass transition temperature (T-g) of the blocks showed little impact on performance. Overall, parameters of both BCP and brush must be simultaneously optimized to achieve high quality DSA.