A Novel Two-Step Annealing Technique for the Fabrication of High Performance Low Temperature Poly-Si TFTs

Low temperature processed (LTP) poly-Si thin film transistors (TFTs) fabricated with a poly-Si film crystallized by a novel two-step annealing (NTSA) technique were investigated and compared with those using conventional solid phase crystallization (SPC) and excimer laser annealing (ELA) schemes. The NTSA scheme is characterized by the combination of an excimer laser induced formation of nucleation centers and a short-time low temperature furnace annealing (about 6 h at 600°C) creating clear crystalline grains with very few in-grain defects. The LTP poly-Si TFTs fabricated with a NTSA poly-Si film not only exhibit a better performance but also significantly shorten the crystallization time as compared to those fabricated using the conventional SPC (about 20 h or longer at 600°C). In addition, the uniformity of the device characteristics for the devices using the NTSA scheme is superior to that using the ELA scheme and is comparable to that using the SPC scheme.