Large grains in thin silicon films were grown by controlling the location of unmolten islands, which are left after near-complete melting of the film during excimer laser crystallization. As the initially amorphous film was first transformed in small grain polycrystalline silicon, these islands contain seeds for crystal growth. To get a single large grain, either the number of seeds was reduced to one or a single one was selected from the seeds by a ‘grain filter’. Former was achieved by making a small indentation in the isolating layer underlying the silicon film so that seeds remain embedded in the indentation. Latter was achieved by making a small diameter hole in the underlying isolating layer, which was filled with amorphous silicon. The lateral growth is preceded by a vertical growth phase during which a single grain is filtered from the initial set of seeds present at the bottom of the hole. In the experiment described, highest yield was achieved for samples in which the melt-depth to hole- diameter ratio was largest.