Directed self-assembly of lamellar microdomains of block copolymers using topographic guiding patterns

A study was conducted to demonstrate an improved graphoepitaxy approach to obtain precise registration of lamellar microdomains of poly(styrene-b-methyl- methacrylate) (PS-b-PMMA) contained in the trench formed between two raised bars. The two-level topographic guiding pattern provided simultaneous alignment and registration of lamellar microdomains. The patterned substrates were fabricated by coating a SiO2 substrate with 100 nm of polyimide and depositing 20 nm of titanium (Ti) on the polyimide. The polyimide was etched with O2 gas to remove the layer and form a 100 nm step in it. The pair of raised aligning patterns guided the alignment of the lamellar perpendicular to the sidewalls, while the pinning pattern at the end of the aligning patterns was oriented perpendicular to their longitudinal direction.