Molecular patterning through high-resolution polymethylmethacrylate masks

Electron beam lithography was used to make nanometer trenches in thin polymethylmethacrylate (PMMA). After development, the wafers were dipped in an aqueous solution of the Creutz–Taube ion $\mathrm{[(}{\mathrm{NH}}_3{)}_5\mathrm{Ru}(\mathrm{pyrazine})\mathrm{Ru}({\mathrm{NH}}_3{)}_5\mathrm{](o-}\mathrm{toluenesulphonate}{)}_5$ (CT5), and the PMMA was removed with acetone or dichloromethane. Atomic force microscopy and x-ray photoelectron spectroscopy were used to investigate the surface characteristics of wafers after dissolution of the PMMA and to confirm the binding of a monolayer of CT5 molecules on the wafer within the areas delimited by the PMMA trenches. This masking technique has so far been demonstrated to pattern 35 nm lines of a monolayer of CT5 molecules on silicon dioxide.