Patent ID: 7902010

Claim:
A method for forming a polysilicon layer in an amorphous silicon layer, comprising: providing a substrate; forming an amorphous silicon layer on the substrate; providing a mask, the mask having at least one first window, one second window, one third window, and one fourth window, each window having a length extending along a first direction, wherein the second window is aligned to the first window with a width smaller than that of the first window, the third window is located adjacent to the first window, and the fourth window is aligned to the third window with a width greater than that of the third window; applying a laser and the mask on the substrate to crystallize the amorphous silicon layer and form a plurality of first crystallizing regions corresponding to the first window and the fourth window; moving the mask or the substrate along the first direction to have the second window and the third window focusing on a central protrusion formed in the first crystallizing regions; and melting the amorphous silicon layer through the mask to lower down the central protrusion and to crystallize the amorphous silicon layer to form a plurality of second crystallizing regions corresponding to the first window and the fourth window, respectively.