Fabrication of colloidal gold micro-patterns using photolithographed self-assembled monolayers as templates

This paper provides a new method for the patterned metallization of self-assembled monolayers. Colloidal Au micropatterns were formed on photolithographed self-assembled monolayers (SAMs) of (3-mercaptopropyl)-trimethoxysilane (MTS) on SiO 2-coated Si substrates. As confirmed by scanning electron microscopy (SEM), the colloidal Au closely replicated the mask features. Atomic force microscopy (AFM)showed that the colloidal Au particles on the unirradiated monolayers of (3-mercaptopropyl)-trimethoxysilane were connected and an almost continuous monolayer of Au nanoparticles was formed. X-ray photoelectron microscopy (XPM) revealed that the -SH terminal groups of the MTS monolayer in the exposed region were oxidized and the self-assembly of colloidal Au onto the unexposed region were through Au–S covalent bounding. The present approach may be applicable to assembly of microelectronic circuits and microbiosensors.