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Thin liquid films on solid substrates are of considerable relevance in widespread of natural and technological fields. Examples are eye irrigation, biological cell interaction, tertiary oil recovery, coating, painting, lubrication, integrated circuits, micro- and nano-electronic devices, to name just a few. It is well known that liquid films are not always stable and there are verities of factors that may destabilize and expose the film to dynamical processes which leads to removal of the liquid from the substrate, the phenomenon so-called dewetting, either by nucleation or spinodal mechanisms. In many cases dewetting is destructive but there are several situation in which dewetting turns... 

Evaporation and condensation of thin films can rupture or stabilize thin film .We show that evaporation hastens dewetting of a thin film. Dewetting over nanometric downward step causes pinning of the contact line near the step. This phenomena is not permanent and after certain time that contact angle reaches to its critical value depinnnig happens. We also study the effect of the step size, contact angle, film thickness, slip and evaporation on the depinning time of the contact line. We show that depinnig time has a reverse relation with the rate of evaporation