Block copolymer thin films: pattern formation and phase behavior

During the last decade, research on thin, sub-micron thick, block copolymer films was devoted toward understanding and controlling microstructural. and topographical features at temperatures T < T-ODT, where T-ODT is the order-disorder transition temperature below which thermodynamic interactions favor the formation of ordered (phase separated) microstructures. Symmetric diblock copolymers, the subject, of this review, undergo an isotropic to lamellar transition when T < T-ODT. Topographical features, 'islands' or 'holes,' of these films typically reflect the underlying phase separation; and the dimension of these features, normal to the substrate, is equal to the interlamellar spacing, L. Two aspects of block copolymer thin films that have not received much attention are discussed in this paper: (1) pattern formation in symmetric block copolymers under conditions of T > T-ODT; and (2) phase behavior of thin film symmetric diblock copolymer/homopolymer mixtures, when T < T-ODT. (C) 2001 Elsevier Science B.V. All rights reserved.