A method and system for processing at least one portion of a thin film sample on a substrate, with such portion of the film sample having a first boundary and a second boundary. One or more first areas of the film sample are successively irradiated by first beamlets of an irradiation beam pulse so that the first areas are melted throughout their thickness and allowed to re-solidify and crystallize thereby having grains grown therein. Thereafter, one or more second areas of the film sample are irradiated by second beamlets so that the second areas are melted throughout their thickness. At least two of the second areas partially overlap a particular area of the re-solidified and crystallized first areas such that the grains provided in the particular area grow into each of the at least two second areas upon re-solidification thereof.