US Patent 7501211 Laser mask and crystallization method using the same

A crystallization method includes providing a substrate having a silicon thin film; positioning a laser mask having first to fourth blocks on the substrate, each block having a periodic pattern including a plurality of transmitting regions and a blocking region; and crystallizing the silicon thin film by irradiating a laser beam through the laser mask. A polycrystalline silicon film crystallized by this method is substantially free from a shot mark, and has uniform crystalline characteristics.