Directed Self-Assembly of POSS Containing Block Copolymer on Lithographically Defined Chemical Template with Morphology Control by Solvent Vapor

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.