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A polycrystalline silicon thin-film transistor (TFT) technology, field-aided lateral crystallization (FALC), has been explored. Polycrystalline silicon thin film, as an active layer, was prepared by applying an electric field to amorphous silicon film during Ni metal-induced lateral crystallization (MILC). Compared with the conventional metal-induced lateral crystallization thin-film transistors (MILC TFTs), these field-aided lateral crystallization thin-film transistors (FALC TFTs) show a low off-state leakage current of 1.79×10−11 A at Vg=−10 V and a high on/off current ratio of 8.82×105. Moreover, the threshold voltage is lower and field-effect mobility is higher than those of MILC TFTs. Therefore, the possibility of high-performance and low-temperature (<500 °C) polycrystalline silicon TFTs was demonstrated by using FALC technology.

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The crystallization properties of amorphous silicon ͑a-Si͒ thin film deposited by rf magnetron sputter deposition with substrate bias have been thoroughly characterized. The crystallization kinetics for films deposited with substrate bias is enhanced relative to unbiased a-Si by films. The enhanced crystallization for substrate biased a-Si films are attributed to ion enhanced nucleation of crystallites during sputter deposition which subsequently grow during the postdeposition anneal. Conversely films sputter deposited without substrate bias have more intrinsic defects and residual oxygen which enhance nucleation and retard growth, respectively, and lead to a large number of small crystallites.

We propose a noble crystallization method of amorphous silicon thin film in this study. Directional crystallization of amorphous silicon thin film was successfully achieved by applying a DC field during heat treatment. The crystallization temperature was lowered to 500°C by employing a trace amount of Ni. The lateral crystallization velocity was 21 µm/h when 53.5 V/cm electric field was applied at 500°C. It also showed the dependence on the applied field intensity. The directionality of the resulting crystallization depended on the polarity of the electric field. This noble technology can be applied to the fabrication of low temperature poly-Si thin film transistors on glass substrates.