Experimental studies were performed to investigate the interaction of a silicon surface and the gaseous phase of a microwave multipolar plasma produced by distributed electron cyclotron resonance (MMP-DECR) using a TEOS-O-2 mixture. Diagnostics of the plasma, carried out with mass spectrometry, has shown a total dissociation of TEOS molecules at a low microwave power (approximate to 100 W). The importance of the gas distribution in the reactor with regard to the film stoichiometry and the growth rate has been demonstrated using three different gas inlet configurations. Uniform layers were obtained with centrally injected gas inlets. Growth rate measurements for the TEOS-O-2 mixture have brought into evidence the simultaneous activities of the growing and etching processes, the latter coming into marked evidence from a certain proportion of O-2 in the mixture and beyond.