Two kinds of polyhedral oligomeric silsesquioxane (POSS)-containing block copolymers (BCPs), namely PS-b-PMAPOSS and PMMA-b-PMAPOSS, were synthesized by living anionic polymerization. A wide range of molecular weights were obtained with a very narrow polydispersity index of less than 1.09. The bulk samples prepared by slow evaporation from a polymer solution in chloroform exhibit well-defined microphase-separated structures with long-range order. Thermal annealing induced hierarchical structures consisting of a smaller length scale ordered crystalline POSS domains within the larger microphase-separated structures. We report detailed structural characterization of these hierarchical structures in bulk and thin films by transmission electron microscopy and grazing incidence wide-angle X-ray scattering (GIWAXS). On the basis of this structural analysis, we propose a model for the formation of an orthorhombic lattice structure through the aggregation of POSS segments which formed a helix-like structure.

We report the self-assembly of organic-inorganic block copolymers (BCP) in thin-films by simple solvent annealing on unmodified substrates. The resulting vertically oriented lamellae and cylinders are converted to a hard silica mask by a single step highly selective oxygen plasma etching. The size of the resulting nanostructures in the case of cylinders is less than 10 nm.

No abstract

Strongly segregating block copolymers (BCPs) are attractive as a means of forming 10 nm scale lithographic features. Here, we report directed self-assembly of polyhedral oligomeric silsesquioxane containing block copolymers (PMMA-b-PMAPOSS) with feature density multiplication to form long-range ordered arrays of dots having areal densities of ∼4 tera dots per square inch via controlled solvent annealing. The degree of swelling of PMMA-b-PMAPOSS thin film during the carbon disulfide solvent annealing was optimized to give the polymer chain mobility to form the desired microdomain structure. Because the annealing solvent is not fully neutral to the components of the BCP, the types of microstructures formed depend strongly on the degree of swelling. We demonstrated that the directed self-assembly with 4× density multiplication of the chemically patterned template can be performed successfully under the optimized condition of solvent annealing and hexagonally packed dots array with 12 nm lattice spacing was produced. We also showed that the microdomain structures formed by solvent-annealing the BCP on the chemically patterned template could tolerate several percent of mismatch between the lattice spacing of the BCP and that of the template. In this study the morphology was limited to hexagonally packed dots. However, the results strongly support the potential application of the technique to form 10 nm scale features of other desired geometries.