An electron cyclotron resonance microwave plasma processing system consisting of a plasma chamber and a processing chamber as well as a new apparatus called the ‘‘species selector and energy controller (SSEC)’’ are described in detail. Silicon dioxide (SiO2) films fabricated using this system without and with the SSEC are used for various experiments to demonstrate that the SSEC can effectively suppress the damaging effects resulting from the bombardment on the substrates and the on‐growing films by energetic particles and photons produced in the plasma during film deposition, as well as effectively reduce the upstream diffusion of the reactant gas from the processing chamber to the plasma chamber, thus suppressing the formation of microdust particles due to the heterogeneous gas phase reaction. The film growth for the films fabricated without the SSEC is due mainly to mass‐limited reaction and that with the SSEC is due to surface rate‐limited reaction. The electronic properties of the SiO2films fabricated with the SSEC at temperatures higher than 250 °C approach those of high‐quality thermally grown silicon oxides. The effects of the SSEC on the film properties and the film growth mechanism are also discussed.