Nanopatterned Polymer Brushes by Reactive Writing

Nanopatterned polymer brushes were prepared selectively by self-initiated photografting and photopolymerization (SIPGP) on carbonaceous deposits created by electron beam induced damage of self-assembled monolayers (SAMs) of 1H,1H,2H,2H-perfluorooctyltriethoxysilane SAM (PF-SAM) on silicon oxide. This patterning approach is referred to as reactive writing (RW). With the monomer, N,N-dimethylaminoethyl methacrylate (DMAEMA), we demonstrate the straightforward formation of polymer brush gradients and single polymer lines of sub-100 nm lateral dimensions because of the high reactivity contrast to the nonirradiated PF-SAM background. The lithography parameters acceleration voltage, irradiation dose, beam current and dwell time were systematically varied to optimize conditions for the conversion of the SAM into carbonaceous deposit and overall resolution of the e-beam based patterning. The results of RW were compared to patterns prepared by carbon templating (CT) under analogue conditions revealing a dwell time dependency, which differs from previous reports. This new RW technique adds new aspects to e-beam lithography techniques as not only the chemistry of the created polymer patterns can be varied but also the surrounding surface chemistry.