Application of organic monolayers formed on Si(111): possibilities for nanometer-scale patterning

The modification of hydrogen-terminated Si(1 1 1) wafer surfaces was reprod uced by previously reported methods of the electrolysis of para-substituted benzendiazonium salts and the Grignard reaction with various alkyl moietie s. The electrolysis methods formed partially ordered two-dimensional monola yers, which were however obscured by precipitation of by-products. The Grig nard reaction deposited a monolayer of moieties of alkyl groups randomly ar ranged, which are more suitable for surface passivation. Aiming for the app lication to nanometer-scale monolayer patterning of the Si(1 1 1) wafer sur face, the organic-monolayer-covered Si(1 1 1) surfaces were subjected to el ectron beam bombardment. After electron bombardment with ambient O-2 or H2O introduced, adsorption of oxygen was observed within the beam spot. By imm ersing the bombarded specimen into an aqueous NiSO4 + (NH4)(2)SO4 solution, the oxygen-deposited portions selectively included Ni atoms. This will be useful in constructing nanometer-scale metallic structures over Si wafer su rfaces. (C) 2001 Elsevier Science B.V. All rights reserved.