Directed self-assembly of PS-b-PMMA block copolymer using HSQ lines for translational alignment

We report here the graphoepitaxial alignment of a lamellar forming PS-b-PMMA block copolymer (BCP) for directed self-assembly using topographical patterns (simple line structures) of hydrogen silsesquioxane (HSQ). The system demonstrates the importance of the sidewall chemistry on translational alignment of BCP domains. A method was developed where a silicon substrate was precoated with a hydroxyl-terminated random copolymer brush of PS-r-PMMA prior to the HSQ feature formation process. The brush ordains the vertical (to the substrate plane) alignment of the BCP lamellar microdomains. Translational BCP alignment is a result of PMMA selectively wetting the HSQ. The formed BCP pattern was selectively etched to remove the PMMA domain allowing direct imaging and to demonstrate capability in forming an on-chip mask.