Patent ID: 7015123

Claim:
A method of crystallizing an amorphous silicon film, comprising; forming an amorphous silicon film on a substrate; irradiating the amorphous silicon film using a laser beam that passes through a mask such that laterally grown grains are formed; transversely moving the mask relative to the substrate; and performing a second crystallization such that laterally grown grains adjacent to the crystallized silicon particle regions continue to grow; wherein the mask includes a light absorptive portion for blocking the laser beam, a plurality of first light-transmitting tiered portions, wherein the tiered portion includes a plurality of tiers adjacent to one another with successively smaller lengths, and a second light-transmitting tiered portion, wherein the tiered portion includes a plurality of tiers adjacent to one another with successively smaller lengths, and wherein the first and second light-transmitting tiered portions pass the laser beam, wherein the second light-transmitting portion is located between the first light-transmitting portions, and wherein each tier has a fixed width; wherein the mask is transversely moved relative to the substrate by the width of each tier; and wherein the laser beam that passes through the mask melts the amorphous silicon film into liquid silicon, wherein a plurality of grain growth regions, comprised of laterally grown grains and crystallized silicon particles, are formed from solidifying liquid silicon, and wherein the laterally grown grains are formed by growing laterally from an interface between liquid silicon and solid silicon.