The deposition of amorphous SiO2 at low temperature in an integrated distributed electron cyclotron resonance (IDECR) reactor is studied. Due to planar geometry such deposition process can be scaled-up for processing of large surfaces. Stoichiometric and dense silica films are deposited without bias at room temperature from a SiH4 + O-2 mixture at high deposition rates (>2 nm/s). Optical properties of the films are analyzed by UV-visible spectroellipsometry. The influence of gas flows, pressure and microwave power is investigated. The gas phase is found to determine the film stoichiometry, the SiH4 flow being the growth rate Limiting factor. Optical properties match those of thermal silica, Electrical properties appear promising even for electronic applications.