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

A method of fabricating a thin film transistor comprising:

• providing a substrate;
• forming an amorphous semiconductor layer over the substrate;
• crystallizing the amorphous semiconductor layer in a first direction, etching the crystallized semiconductor layer, and crystallizing in a second direction to form a polycrystalline semiconductor layer;
• forming a gate insulating layer on the polycrystalline semiconductor layer;
• forming a gate electrode on the gate insulating layer;
• forming an insulating layer on the substrate;
• and
• forming a source electrode and a drain electrode contacting the polycrystalline semiconductor layer.

A method of fabricating a thin film transistor comprising:

• providing a substrate;
• forming an amorphous semiconductor layer over the substrate;
• crystallizing the amorphous semiconductor layer into a polycrystalline semiconductor layer having grains with a quasi-rectangular shape;
• forming a gate insulating layer on the polycrystalline semiconductor layer;
• forming a gate electrode on the gate insulating layer;
• forming an insulating layer on the substrate;
• and
• forming a source electrode and a drain electrode contacting the polycrystalline semiconductor layer.

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 on the first substrate, laterally crystallizing the amorphous semiconductor layer in a first direction, etching the crystallized semiconductor layer, and laterally crystallizing the 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.