Hiroshi Yoshida, Hyo Seon Suh, Abelardo Ramírez-Hernández, Jeong In Lee, Kouhei Aida, Lei Wan, Yoshihito Ishida, Yasuhiko Tada, Ricardo Ruiz, Juan de Pablo, Paul F. Nealey
Thrust 1 research has demonstrated that it is possible to achieve resolution enhancements with directed assembly via density multiplication, in which the density of features of the assembled block copolymer film is an integer multiple n of the feature density of the underlying pattern. Beyond density multiplication, feature resolution can also be improved by using block copolymers that microphase separate into domains that are smaller than what can be achieved with polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA), the most commonly used block copolymer in previous studies of directed self-assembly.
One block copolymer that can microphase separate into smaller domains than PS-b-PMMA is polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP). The challenge with PS-b-P2VP, as with most block copolymers, is that one block has a lower surface energy than the other. Thrust 1 researchers, in collaboration with industrial partners have demonstrated that the use of a top layer to control of the interfacial energies of the blocks of copolymer with a top layer could result in through-film, perpendicular lamellae.