Binary nanopatterned surfaces prepared from silane monolayers

We report on the fabrication of planar surfaces bearing nanoscale chemical patterns, obtained by combining electron beam lithography and gas-phase silanation, offering an unprecedented range of chemical functionalities down to the 20-25-nm feature size level. Compared to previously reported methods, this method combines a number of desirable features such as high resolution, a large range of accessible chemical functions, the possibility to pattern large surfaces, and the potential for higher throughput. The formation from the gas phase of silane monolayers of high quality and varying chemical functionality is shown to be achievable through the nanoholes of poly(methyl methacrylate) (PMMA) masks prepared by e-beam nanolithography on Si wafers. The removal of the mask and subsequent silanation of the background provides ultraflat surfaces chemically nanopatterned over large areas. The patterns were imaged and characterized by atomic force microscopy (AFM). The patterned surfaces can be used, for instance, to direct macromolecular assembly, as demonstrated by controlling the deposition of polyelectrolyte multilayers on the 150-nm scale.