Periodically lateral silicon grains fabricated by excimer laser irradiation with a-Si spacers for LTPS TFTs

Abstract

Low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) with a periodic lateral silicon grain structure have been demonstrated to exhibit high-performance electrical characteristics via the amorphous silicon spacers above the amorphous silicon film crystallized with excimer laser. Amorphous silicon spacers allowed the bottom of the under-layered amorphous silicon film to serve as seed crystals. The periodic grain structure could be artificially controlled via the super lateral growth phenomenon during excimer laser irradiation. Consequently, such periodically large and lateral grains in the TFTs would achieve high field-effect-mobility of 298 cm(2)/V s, as compared with the conventional ones of 128 cm(2)/V s. In addition, the uniformity of device-to-device could be improved due to this location-manipulated lateral silicon grains. (c) 2006 The Electrochemical Society.