Patterning of self-assembled alkanethiol monolayers on silver by microfocus ion and electron beam bombardment

Decanethiol [CH3(CH2)9SH] self-assembled monolayer films on silver substrates have been irradiated in selected areas by focused ion or electron bombardment. Subsequent immersion of the irradiated sample in a solution of a fluoromercaptan [CF3(CF2)2(CH2)2SH] results in attachment of this molecule to the silver surface in the ion or electron-exposed regions, producing a micrometer spatial-scale pattern of two chemically distinct alkanethiol monolayers. The coverage of the fluoromercaptan on the bombarded areas was found to reach maximum levels of 70% at ion doses of 6×1013 ions/cm2 and 50% at electron doses of 2×1017 electrons/cm2 as determined by secondary ion mass spectrometry. These methods of maskless patterning may be useful for semiconductor or biosensor device fabrication.