Crystallization method and apparatus thereof

1. 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.

2. The method according to claim 1 , wherein the stage moves at one time.

3. The method according to claim 1 , wherein the performing the first and second crystallizations are carried out by moving the stage and synchronizing a movement speed of the stage with a triggering of the laser beam.

4. The method according to claim 3 , wherein the movement speed of the stage and the triggering of the laser beam are synchronized by using a computer system.

5. The method according to claim 1 , wherein the substrate is an array substrate of a liquid crystal display device on which a thin film transistor array is formed.

6. The method according to claim 1 , wherein the stage moves along the width direction of the laser beam with a substantially constant speed.

7. The method according to claim 1 , wherein the stage moves with different speeds for the first region and the second region.

8. The method of claim 1 , wherein the stage moves with a faster speed for the first region than for the second region.

9. The method according to claim 1 , wherein the first crystallization is achieved by controlling a triggering of the laser beam to be synchronized with the first distance.

10. The method according to claim 1 , wherein the second crystallization is achieved by controlling a triggering of the laser beam to be synchronized with the second distance.

11. The method according to claim 1 , wherein the first crystallization is carried out to allow a grain to have the same size as the first distance.

12. The method according to claim 1 , wherein the second crystallization is repeatedly carried out to increase a grain size.

13. The method according claim 1 , wherein the first crystallization and the second crystallization are carried out by using a sequential lateral solidification for laterally growing grains.