Ta2O5 and SiO2 multilayer stacks have been deposited on silicon (100) substrate at 850 degrees C and 550 degrees C by a new process, which consists of injecting small and accurate quantities of precursor into an LPCVD reactor. Injections of the metalorganic precursors of tantalum and silicon have been achieved with two high speed electro-valves. AFM and TEM characterizations show that Ta2O5 thin film deposited at 850 degrees C has a very rough surface, whereas at 600 degrees C ii presents a smooth surface. From the TEM images of the multilayers, a similar behavior is observed.