High-performance low-temperature poly-Si TFTs crystallized by excimer laser irradiation with recessed-channel structure

High-performance low-temperature poly-Si (LTPS) thin-film transistors (TFTs) have been fabricated by excimer laser crystallization (ELC) with a recessed-channel (RC) structure. The TFTs made by this method possessed large longitudinal grains in the channel regions, therefore, they exhibited better electrical characteristics as compared with the conventional ones. An average field-effect mobility above 300 cm/sup 2//V-s and on/off current ratio higher than 10/sup 9/ were achieved in these RC-structure devices. In addition, since grain growth could be artificially controlled by this method, the device electrical characteristics were less sensitive to laser energy density variation, and therefore the uniformity of device performance could be improved.