A comparison was made of thin films of silicon dioxide deposited, at floating temperatures, using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD) and distributed electron cyclotron resonance plasma enhanced chemical vapor deposition (DECR PECVD). The refractive index, composition, and chemical bonding of the plasma oxides were determined by null and spectroscopic ellipsometry, nuclear reaction analysis, and Fourier transform infrared spectroscopy and were compared with thermal oxides. The damaged layer at the Si/SiO2 interface resulting from ECR and DECR techniques was evaluated by spectroscopic ellipsometry. Finally, high frequency and quasi-static capacitance voltage characteristics and ramped current voltage measurements were performed to determine the electrical properties of the ECR and DECR deposited silicon oxide. Device quality SiO2 thin films have been prepared using both deposition techniques : low interface state density [5x10(10) eV(-1) cm(-2) (ECR) or 2.5x10(10) eV(-1) cm(-2) (DECR)], and high critical field [5.2 MV/cm (ECR) or 6 MV/cm (DFCR)] have been achieved.