Aluminum oxide (A12O3), nitride(A1N) and silicon nitride(SiN) films were prepared at a low substrate temperature of 100°C. Film resistivity was higher than 5x1013 Ω-cm and the breakdown voltage was greater than 3x10° V/cm. The films deposited on sapphire and silicon substrates were very flat, and were chemically and thermally stable. The A1-O, A1-N and Si-N bonds could be formed effectively by using both ionized clusters and reactive gas ions, and transparent and good quality films were obtained. Through these results, the simultaneous use of an ionized cluster beam (ICB) system and a microwave ion source was found to have a high potential for preparing oxide and nitride films at a low substrate temperature.