A two-pass excimer laser annealing process to control amorphous silicon crystallization

A new approach to control the lateral-growth mechanism of polycrystalline silicon films through appropriate spatial modulation of the absorbed laser energy and with a two-pass excimer laser annealing process is presented. In the first pass, spatial modulation of the light intensity has been achieved by irradiating the precursor amorphous silicon films through a patterned mask in contact with the sample, triggering the lateral growth of grain in excess of 1 mu m. During the second pass of the process, the film is reirradiated without the mask and the laterally grown grains can be used as seeds and can be propagated to crystallize the film uniformly. With optimized mask patterns the sample area can be fully covered with laterally grown grains.