A high-performance polysilicon thin-film transistor using XeCl excimer laser crystallization of pre-patterned amorphous Si films

Abstract

A high-performance polysilicon thin-film transistor (TFT) fabricated using XeCl excimer laser crystallization of pre-patterned amorphous Si films is presented. The enhanced TFT performance over previous reported results is attributed to pre-patterning before laser crystallization leading to enhanced lateral grain growth. Device performance has been systematically investigated as a function of the laser energy density, the repetition rate, and the number of laser shots. Under the optimal laser energy density, poly-Si TFT's fabricated using a simple low- temperature (/spl les/600/spl deg/C) process have field-effect mobilities of 91 cm/sup 2//V/spl middot/s (electrons) and 55 cm/sup 2//V/spl middot/s (holes), and ON/OFF current ratios over 10/sup 7/ at V/sub Ds/=10 V. The excellent overall TFT performance is achieved without substrate heating during laser crystallization and without hydrogenation. The results also show that poly-Si TFT performance is not sensitive to the laser repetition rate and the number of laser shots above 10.