A new polycrystalline silicon TFT with a single grain boundary in the channel

A new excimer laser annealing method, which results in large lateral polysi licon grains exceeding 1.5 mum, has been proposed and polycrystalline silic on thin film transistors (poly-Si TFTs) with a single grain boundary in the channel have been successfully fabricated. The proposed method employs a l ateral grain growth phenomenon obtained by excimer laser irradiation on an amorphous silicon layer with pre-patterned aluminum film. The aluminum patt erns act as a masking layer of incident laser beam for the selective meltin g of amorphous silicon layer. The uniform and large grains are obtained nea r the edge of the aluminum patterns. When two aluminum patterns are separat ed by a 2 mum space, the solidified region (i.e., poly-Si channel) exhibits a single grain boundary. The n-channel poly-Si TFT fabricated by the propo sed method shows considerably improved I-V characteristics, such as high fi eld effect mobility exceeding 240 cm(2)/Vs.