Excimer laser processing for a-Si and poly-Si thin film transistors for imager applications

Pulsed excimer laser annealing (ELA) has become an important technology by which to produce high performance thin film transistors (TFTs) for large ar ea electronics. The applications of these advanced TFTs in flat-panel displ ays and flat-panel imagers for two-dimensional x-ray imaging have attracted much interest. TFTs made from excimer laser crystallized poly-Si thin film s with mobilities higher than 100 cm(2)/V s and off-state leakage currents lower than 2 fA/mu m at drain voltage V-D = 5 V have recently been achieved . The improved off-state leakage current enables one to consider making fla t-panel imagers based on poly-Si TFT technology. Laser doping or dopant act ivation is another important application of the ELA process. Using a laser doping process, we have fabricated a-Si TFTs with self-aligned poly-Si sour ce/drain contacts. These new devices have reduced source/drain parasitic ca pacitance and their channel length can easily be scaled down. In this artic le, we will review the excimer laser processing technology for both the pol y-Si TFT technology and self-aligned a-Si:H TFT technology and report the c urrent status of developing flat-panel imagers using these new TFT technolo gies. (C) 2000 American Vacuum Society. [S0734-2101(00)11904-9].