We demonstrate that precipitation of implanted erbium ions at silicon-polymer interface initiates oxidation reaction of Si(1 0 0) surface at room temperature. Oxidation reaction starts through spontaneous formation of circular patches of SiOx and the diameter of these circles grows uniformly with time and touch each other to cover the entire surface by keeping the thickness of these patches almost fixed at 4 nm. The nucleation and inplane growth rates of SiOx, circles are found to be dependent on the fluence of erbium-implantation, the condition of substrate and can be controlled by controlling oxygen partial pressure of the environment. In addition to the precipitation of erbium ions at silicon-polymer interface, enhancement of concentration of erbium ions was observed at periodic depths within polymer film confirming that in ultra-thin films polymer molecules form layers parallel to substrate surface due to confinement. (c) 2005 Elsevier B.V. All rights reserved.