SiO2 insulator films were deposited at low temperature below 150 °C using organic silicon source of tetramethylsilane (4MS) and N 2O precursor by ICP-CVD method. FT-IR absorption peaks of O-H stretch, Si-H stretch, Si-CH3 stretch were not observed in these SiO2 films. Refractive index of SiO2 films at 100 °C was 1.480. These results indicate that SiO2 insulator films can be obtained by high density plasma ICP-CVD using 4MS and N2O by increasing substrate temperature to 100 °C.