Patent ID: 7229860

Claim:
A method of manufacturing a thin film transistor, comprising: crystallizing an amorphous silicon thin film by illuminating laser beam onto the amorphous silicon thin film using a lateral solidification process to form a polysilicon thin film, wherein the lateral solidificating process uses a mask having a plurality of slit patterns defining transmission regions of the laser beams, and the slit patterns are aligned in a first direction and a second direction perpendicular to the first direction on at least two areas such that grains of the polysilicon layed grow in at least two directions; smoothing a surface of the polysilicon thin film by plasma dry-etching process; forming a semiconductor layer by patterning the polysilicon thin film; forming a gate insulating film covering the semiconductor layer; forming a gate electrode on the gate insulating film opposite the semiconductor layer; forming a source region and a drain region opposite each other with respect to the gate electrode by implanting impurity into the semiconductor layer; and forming a source electrode and a drain electrode electrically connected to the source region and the drain region, respectively.