  We study the formation of nanometer thick oxide layers around nanoparticles
(plateaus) in a wet nitrogen environment over 32 days. We determine both the
plateau height and the lateral force needed to remove the particles with an
atomic force microscope (AFM). The height is well described by the Deal-Grove
model for a thermally activated diffusion limited oxidation process.
Furthermore, we observe that height and force appear to be correlated
suggesting that the rise in adhesion forces is mainly governed by an oxidation
process. Since the plateaus are the result of a change in the chemical
structure, the surface remains permanently altered even after the removal of
the nanoparticles. This observation is of great importance for many
applications requiring smooth silicon surfaces, such as photolithography, where
small contamination can cause the observed oxidation process and significantly
increase the surface roughness.
