Selective crystallization method and laser crystallization apparatus used in the selective crystallization method

1. A selective crystallization method comprising:

placing a first substrate on a second substrate, wherein the first substrate comprises first crystallization regions and the second substrate comprises second crystallization regions, such that the first crystallization regions and the second crystallization regions do not overlap each other; and

crystallizing the first and second crystallization regions with a single laser beam.

2. The method of claim 1 , wherein at least one of the first substrate and the second substrate is transparent.

3. The method of claim 1 , wherein crystallizing the first and second crystallization regions comprises at least one of moving the single laser beam in a first direction, or moving the first substrate and the second substrate in the first direction.

4. The method of claim 1 , wherein the first crystallization regions and the second crystallization regions comprise an amorphous silicon.

5. A selective crystallization method comprising:

placing a first substrate, the first substrate having first crystallization regions, on a second substrate, the second substrate having second crystallization regions, such that the first crystallization regions and the second crystallization regions are arranged alternately; and

simultaneously crystallizing the first crystallization regions and the second crystallization regions by irradiating a laser beam to the first substrate and the second substrate,

wherein the laser beam is split into a first sub-laser beam and a second sub-laser beam which are simultaneously irradiated to the first crystallization regions and the second crystallization regions.

6. The method of claim 5 ,

the laser beam is split into the first sub-laser beam which travels toward the second substrate and the second sub-laser beam which is at a predetermined angle to the first sub-laser beam, and

the first sub-laser beam is irradiated to the second crystallization regions, and the second sub-laser beam is reflected toward the first substrate to reach the first crystallization regions.

7. The method of claim 5 , wherein the first sub-laser beam is irradiated to the second crystallization regions, the second sub-laser beam is irradiated to the first crystallization regions, and an optical path of the second sub-laser beam is adjusted to be the same as that of the first sub-laser beam.

8. The method of claim 7 , wherein

the second sub-laser beam travels a distance equal to the predetermined distance between the first substrate and the second substrate from a location at which the laser beam is split;

the second sub laser beam is reflected toward the first substrate; and

the second sub laser beam passes through a refractive film having a same thickness and refractive index as the first substrate.

9. The method of claim 5 , wherein the first and the second crystallization regions comprise amorphous silicon.

10. The method of claim 5 , wherein at least one of the first substrate and the second substrate is transparent.