Patent ID: 7553715

Claim:
A method of crystallizing an amorphous silicon thin film on a substrate, comprising: (a) loading a substrate onto a stage, the substrate having an amorphous silicon thin film thereon and having first and second regions, wherein the substrate has a pixel unit corresponding to the first region and a driving circuit unit corresponding to the second region; (b) performing a first crystallization to grow a primary grain with a length corresponding to a half of a laser beam width in a width direction of the laser beam by irradiating the laser beam on the first region of the amorphous silicon thin film; (c) moving the stage in the width direction of the laser beam by a first distance (D 1 ) in a condition of W/2<D 1 <W (where, W is a width of the laser beam) and irradiating the laser beam to obtain a secondary grain which has a same length as the first distance, wherein the secondary grain grows from a certain region of the primary grain on which the laser beam is overlapped; (d) performing the step of (c) several times to crystallize the entire first region of the amorphous silicon thin film; (e) performing a second crystallization to grow a primary grain with a length corresponding to the half of the laser beam width by irradiating the laser beam on the second region of the amorphous silicon thin film; (f) moving the stage in the width direction of the laser beam by a second distance (D 2 ) in a condition of 0≦D 2 ≦W/2 and irradiating the laser beam to obtain a secondary grain which has a length adding the second distance and the length of the primary grain; and (g) performing the step of (f) repeatedly to obtain a grain having a longer length.