Low-Temperature Polycrystalline Silicon Thin-Film Transistors for Large-Area Liquid Crystal Display

Abstract

A low-temperature poly-Si thin-film transistor (TFT), having inverted-staggered structure, has been developed successfully using excimer laser annealing and ion doping. This TFT is suitable for pixel transistors of large-area and high-resolution LCDs. The maximum process temperature of the TFT fabrication steps is less than 450°C, so the same glass substrate on which amorphous Si TFT arrays are formed can be used in this poly-Si TFT process. Furthermore, most of the procedures, equipment and thin-film materials used to fabricate amorphous Si TFTs are compatible with fabrication of the poly-Si TFTs. On the other hand, some investigation of the CMOS driver circuit has been done, and it has been found that the threshold voltage of these poly-Si TFTs can be controlled easily by lightly doping of B ion into the channel region using the ion doping system.