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Block copolymers (BCPs) of an A-block-(B-random-C) architecture have been explored as materials for nanolithography because the composition and chemistry of the random block enables modification of thermodynamic and wetting properties to meet manufacturing criteria. Here, A-b-(B-r-C) BCPs created by an amidation reaction of polystyrene-block-poly(pentafluorophenyl methacrylate) (PS-b-PPFMA) with controlled amounts of Si add insight to previous conclusions about the dual contributions of BCP chemistry and reactive ion etch (RIE) gas chemistry on etch properties. We focus on two RIE etch characteristics: organosilicon etch resistance in H2/N2 plasma etching and enhanced removal of non-styrenic structures in an Ar/O2 etch. Consistent with previous studies, higher amounts of Si result in greater etch resistance under H2/N2 RIE, where at least ∼10 wt. % Si is necessary to exhibit sufficient etch resistance. By contrast, Ar/O2 etching resulted in etch rates independent of Si content. We observe previously unreported surface roughening aligned with morphological domains during the H2/N2 etch of modified PS-b-PPFMA BCPs. Limited in the amount of allowable Si to attain equal surface energy between blocks, these BCPs are further disqualified in forming a Si-containing mask. However, in an Ar/O2 etch, the same BCPs exhibit suitable etch contrast and smooth domain structures, forming a uniform PS mask. Ultimately, this study uses the chemical flexibility of these materials to demonstrate the mechanisms of interactions between BCP and etch chemistry that must be considered to design effective materials for pattern transfer applications. 

ABSTRACT Recent interest in manipulating the chemistry of block copolymers (BCPs) to manage the covarying properties necessary to meet manufacturing criteria in nanolithography has resulted in the development and expansion of the A‐block‐(B‐random‐C) BCP architecture, where the random block allows for the decoupling of thermodynamic and wetting properties. Previous reports of such BCPs have used click chemistry to create the desired random block, but all such instances possess additional functional groups that are susceptible to undesirable side reactions upon annealing, such as cross‐linking and surface grafting. This study reports the substitution reaction of polystyrene‐block‐poly(pentafluorophenyl methacrylate) (PS‐b‐PPFMA) with primary amines. The resulting methacrylamide structure of the functionalized random block has only an amide linkage between the attached functional group and the polymer backbone, thereby omitting any sources of side reactions within the BCP. The outcomes of this report also demonstrate the enhanced thermal stability of these materials by virtue of their stable amide bonds. A range of random copolymer compositions is assessed to develop BCPs in which the random block has approximately the same surface energy as the PS block. These BCPs can self‐assemble into perpendicular lamellae and are therefore promising candidates for directed self‐assembly.