Semiconductor device including a tft having large-grain polycrystalline active layer, lcd employing the same and method of fabricating them

Abstract

A semiconductor device has a thin film transistor including an insulating substrate, an island made of a polycrystalline semiconductor material and disposed on the insulating substrate, a conductive layer made of the polycrystalline semiconductor material and at least one of metals and metallic silicides and surrounding the island, a source region and a drain region spaced from the source region, the source region and the drain region being formed in said island, a gate electrode disposed on the island with an insulating film interposed between the island and the gate electrode, the gate facing a spacing between the source region and the drain region. The polycrystalline semiconductor material forming the island and the conductive layer are fabricated by initially annealing a first amorphous semiconductor material deposited on the insulating substrate with a crystallization-inducing layer made of the at least one of metals and metallic silicides and having a hole corresponding to the island, the crystallization-inducing layer being disposed on a surface of the amorphous semiconductor material on at least one of a substrate side thereof and a side thereof opposite from the substrate side, and then by depositing a second amorphous semiconductor material on the first amorphous semiconductor and annealing the second amorphous semiconductor material.