Paper TF-WeM12
Fabrication of Poly-Crystalline Silicon Thin Film by Using a Neutral Beam Deposition Method at a Low Temperature

Wednesday, October 17, 2007, 11:40 am, Room 613/614

Poly-crystalline silicon (p-Si) thin films are generally applied to electronic and optoelectronic devices because of its higher carrier mobility than that of amorphous silicon (a-Si) film and excellent potential in fabricating higher speed, higher resolution and brighter TFT-LCD. Currently, p-Si film is fabricated by re-crystallizing an a-Si film with post-treatment method such as excimer laser annealing (ELA), solid phase crystallization (SPC), metal-induced crystallization (MIC), etc. However, these troublesome post-treatment requires high processing temperature (500~600 °C) which is higher than glass transition temperature. Furthermore, throughput and cost issues will become more critical as the substrate size is increased. Therefore, to simplify process steps and increase production throughput, direct p-Si deposition at a low temperature is definitely required. Chemical assisted neutral beam deposition (CANBD) is investigated as a new approach to fabricate and develop p-Si which has more excellent properties in this study. The difference of CANBD to the conventional PECVD is that the p-Si thin film formation energy of CANBD is supplied by controlled neutral beam energies. Decomposition of source gas (SiH₄) is enhanced by assisted neutral beam which is generated by low energy Ar neutral beam, resulting in the formation of low temperature p-Si. The p-Si made by the neutral beam deposition method shows better electrical property compared to silicon deposited by other processes at low temperature. Resistivity of grown silicon film is measured by 4-point probe measurement. Carrier concentration and carrier mobility are evaluated by Hall measurement. Film crystallinity is investigated by HRTEM, Raman spectroscopy, and X-ray diffraction analysis.