Fabrication of Large Lateral Polycrystalline Silicon Film by Laser Dehydrogenation and Lateral Crystallization of Hydrogenated Nanocrystalline Silicon Films

Hydrogenated nanocrystalline silicon (nc-Si:H) thin-film transistors (TFTs) have attracted attention for application to the operation of organic light-emitting diodes (OLEDs). The monolithic integration of nc-Si:H TFTs and polycrystalline silicon (poly-Si) TFTs and the use of nc-Si:H TFTs for operating an OLED are candidate technologies to achieve OLED system-on-g lass. To develop such a system, it is necessary to fabricate poly-Si films without employing thermal dehydrogenation because hydrogen needs to be maintained in the channel region of nc-Si:H TFTs. In this study, we optimized the laser dehydrogenation process as a substitute for thermal dehydrogenation by using a diode-pumped solid-state continuous-wave green laser (Nd:YVO(4), 2 omega = 532 nm) to fabricate large lateral poly-Si films with grain sizes of 3 x 20 mu m(2). The performance of poly-Si TFTs is well known to be sensitive to the quality of poly-Si films. In order to evaluate the electrical properties of poly-Si films, TFTs were fabricated by conventional processes. The field-effect mobility, threshold voltage, and S-value of the poly-Si TFTs were 220 cm(2) V(-1) S(-1), -1.0 V, and 0.45V/dec, respectively. The quality of the poly-Si film fabricated in this experiment was sufficiently high for the integration of peripheral circuits. (C) 2009 The Japan Society of Applied Physics