The structure of silicon oxide films grown in inductively coupled plasma (ICP) with oxygen gas at temperatures ranging from 350 to 450 degrees C was studied. The thickness of the oxide ranged from 10 to 40 nm. A FTIR spectroscopy showed that the Si-O-Si bond angle was smaller than that in the high-temperature thermal oxide. The bond angle decreased as the oxide thickness decreased. An X-ray reflectivity analysis showed that the density of the ICP oxide (2.23 g/cm(3)) was larger than that of thermal oxide (2.20 g/cm(3)) grown at 900 degrees C. The accumulation of compressive stress could be the cause of small bond angles and the high density in the ICP oxide. A very thin surface layer with a lower density was also detected on the as-grown ICP oxide. The ICP oxide showed a high etch rate and low refractive index as the oxide thickness decreased, indicating that these chemical and physical properties were strongly affected by the magnitude of the Si-O-Si bond angle.