A silicon oxide film has a ratio of A.sub.1 to A.sub.2 which is not higher than 0.21, where A.sub.1 is a first peak integrated intensity of a first peak belonging to Si--OH and appearing in the vicinity of a wave-number of 970 cm.sup.-1, and A.sub.2 is a second peak integrated intensity of a second peak belonging to O--Si--O and appearing in the vicinity of a wave-number 820 cm.sup.-1, and each of the first and second peak integrated intensities is defined as a product of peak width at half height and a peak height of a Raman spectrum obtained by a Raman scattering spectroscopic analysis of the silicon oxide film. The silicon oxide film is deposited under a condition that a ratio of a first flow rate Fo of oxygen gas to a second flow rate Fsi of a silicon source gas is not lower than 20.