The creation of highly efficient guiding patterns for the directed self-assembly of block copolymers by resistless nanolithography using atomic force microscopy (AFM) is demonstrated. It is shown that chemical patterns consisting of arrays of lines defined on a brush layer by AFM allow the alignment of the blocks of lamella-forming polymers. The main advantage of this method relies on the capability to create high-resolution (sub-10 nm line-width) guiding patterns and the reduction of the number of process steps compared to the state-of-the-art methods for creating guiding patterns by chemical surface modification. It is found that the guiding patterns induce the block alignment very efficiently, allowing the achievement of a density multiplication factor of 7 for block copolymers of 14 nm half-pitch, which is attributed to the combined effect of topographical and chemical modification.
Keywords: atomic force microscopy; block copolymer self-assembly; chemical guiding patterns.