Method of fabricating polycrystalline silicon thin film for improving crystallization characteristics and method of fabricating liquid crystal display device using the same

1. A method of fabricating a liquid crystal display device comprising:

forming a first thin film transistor in a driving circuit region by using a crystallized semiconductor layer as an active layer by providing a first substrate composed of a pixel region and a driving circuit region, forming an amorphous semiconductor layer having a first thickness on the first substrate, laterally crystallizing the amorphous semiconductor layer in a first direction, partially etching the crystallized semiconductor layer to a second thickness, and laterally crystallizing the partially etched crystallized semiconductor layer in a second direction perpendicular to the first direction;

forming a second thin film transistor in the pixel region;

forming a pixel electrode electrically connected to the second thin film transistor on the first substrate;

providing a second substrate where a color filter layer is formed;

attaching the first substrate and the second substrate to each other; and

forming a liquid crystal layer between the first substrate and the second substrate.

2. The method according to claim 1 , wherein the lateral crystallization of the amorphous semiconductor layer is a sequential lateral solidification.

3. The method according to claim 1 , wherein forming the first thin film transistor includes:

forming a gate insulating layer on the crystallized semiconductor layer;

forming a gate electrode on the gate insulating layer;

forming an insulating layer on the gate electrode; and

forming a source electrode and a drain electrode contacting the crystallized semiconductor layer on the insulating layer.

4. The method according to claim 3 , further comprising injecting an n type impurity into the crystallized semiconductor layer.

5. The method according to claim 3 , further comprising injecting a p type impurity into the crystallized semiconductor layer.

6. The method according to claim 3 , wherein the first thin film transistor and the second thin film transistor are formed in the same fabrication line.

7. The method according to claim 3 , wherein the first thin film transistor and the second thin film transistor are integrally formed.

8. The method of claim 1 , wherein forming the second thin film transistor includes:

forming an amorphous semiconductor layer on a first substrate;

forming a gate electrode on the amorphous semiconductor layer;

forming an insulating layer on the gate electrode; and

forming a source electrode and a drain electrode contacting the crystallized semiconductor layer on the insulating layer.

9. The method according to claim 8 , wherein the first thin film transistor and the second thin film transistor are formed in the same fabrication line.

10. The method according to claim 8 , wherein the first thin film transistor and the second thin film transistor are integrally formed.

11. The method according to claim 1 , wherein the first thickness is approximately 1000˜2000 Å and the second thickness is approximately 300˜600 Å.