The annealing effects of the thin aluminum silicate films grown on Si(100) by sputtering method were investigated using various physical and electrical measurements. All the films grown at the temperature of 300 degreesC using sputtering Al2O3 target show an amorphous structure as examined by x-ray diffraction and transmission electron microscopy. The amorphous structure is maintained up to 700 degreesC and then transformed to crystalline Al1.7SiO0.15O2.85 or mullite phase above the annealing temperature of 800 degreesC. The conduction process, charge trapping and detrapping characteristics, and trap charge density in metal-oxide-semiconductor structure are influenced by the annealing temperature. The depth profiling data using x-ray photoelectron spectroscopy show that the properties are closely related to the change of the interfacial layer and chemical state under the high temperature annealing. The breakdown characteristics are degraded after the annealing temperature of 900 degreesC due to the rapid change of the interfacial layer thickness and chemical state of the silicate layer.