OBSERVATION OF NANO-DEWETTING STRUCTURES

We have studied the dewetting of thin polymer films (polystyrene) on t op of different silicon substrates. With diffuse X-ray scattering and scanning-force microscopy a high in-plane resolution was achieved. Bes ides the well-known mesoscopic dewetting structures of drops with diam eters in the range of several micrometers we detect a further morpholo gical feature. Depending on the thickness of the native silicon oxide layer, inside the dewetted areas small dimples are formed. This nano-d ewetting structure can be understood as the result of the dewetting of a remaining ultra-thin film and is compared with theoretical predicti ons of spinodal decomposition. This observation of another length scal e provides some new aspects on the molecular mechanism of polymer dewe tting.