Aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in a conventional furnace with N2 protection has been studied at reaction temperatures ranging from 200 to 500°C by using optical microscopy, and transmission and scanning electron microscopy. The a-Si and Al layers were deposited with plasma-enhanced chemical vapor deposition (PECVD) and electron beam evaporation, respectively. The structures in the study are Al/a-Si and a-Si/Al on Si or glass wafers coated with 3000 Å PECVD SiO2. It was found that Al induces crystallization of a-Si for both Al/a-Si and a-Si/Al structures by exchanging positions of Al and Si layer through diffusion of Si into Al and the grain size of crystallized Si (c-Si) increases with the decrease of AIC temperature. AIC for Al/a-Si structures starts at a temperature as low as 200°C, which is 100°C lower than that for a-Si/Al structures. Kinetics analysis found that the activation energies are 1.76 eV and 1.65 eV for both Al/a-Si and a-Si/Al structures, respectively. The quality of AIC c-Si depends on the order, thickness and thickness ratio of a-Si to Al. Microstructural observations indicated that the c-Si for Al/a-Si structures is better and more suitable for use in fabrication of thin film transistors (TFTs) than that for a-Si/Al structures.