Control of polystyrene-block-poly(methyl methacrylate) directed self-assembly by laser-induced millisecond thermal annealing

Directed self-assembly of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) during laser thermal annealing at peak temperatures of 300 degrees C-800 degrees C for dwells of 1-10 ms has been explored. The enhanced mobility of polymer chains at these temperatures improves registration compared with conventional thermal anneals. PS-b-PMMA films (forming 15-nm line/space standing lamellae) were cast on chemically patterned substrates with a copolymer neutral layer and annealed by laser and hot plate. Annealing by hot plate or multiple laser scans resulted in well-aligned features over micron length scales. By laser annealing multiple times, defectivity was reduced by similar to 60%. However, laser annealing for only 10 ms before performing a hot plate anneal reduced defectivity by >80%. We believe that this reduction arises from improved interfacial alignment of the film to the template during laser annealing near the order-disorder transition. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)