Application of organic monolayers formed on Si(1 1 1): possibilities for nanometer-scale patterning

The modification of hydrogen-terminated Si(1 1 1) wafer surfaces was reproduced by previously reported methods of the electrolysis of para-substituted benzendiazonium salts and the Grignard reaction with various alkyl moieties. The electrolysis methods formed partially ordered two-dimensional monolayers, which were however obscured by precipitation of by-products. The Grignard reaction deposited a monolayer of moieties of alkyl groups randomly arranged, which are more suitable for surface passivation. Aiming for the application to nanometer-scale monolayer patterning of the Si(1 1 1) wafer surface, the organic-monolayer-covered Si(1 1 1) surfaces were subjected to electron beam bombardment. After electron bombardment with ambient O2 or H2O introduced, adsorption of oxygen was observed within the beam spot. By immersing the bombarded specimen into an aqueous NiSO4+(NH4)2SO4 solution, the oxygen-deposited portions selectively included Ni atoms. This will be useful in constructing nanometer-scale metallic structures over Si wafer surfaces.