Ion doping technology (IDT) for impurity doping is exactly one of the most important technology in the manufacturing of low temperature poly-silicon (LPS) TFT. Improvement of IDT are carried on according to more large-size glass and the requirement of LPS-TFT's performance. IDT has become attractive very much, because it is required the application for forming source/drain, LDD region and adjusting Vth. We have developed ion doping system for large-size glass up to 730 x 920 mm(2). It is focused to achieve using the sheet style (rectangular) beam and scanning glass, and currently we have developed the new system that has the function of mass separation of ion beam. (C) 2002 Published by Elsevier Science B.V.