Metallorganic chemical vapor deposition of Ta2O5 films

Abstract

Ta2O5 films were grown by Pulsed-Metal Organic Chemical Vapor Deposition (Pulsed-MOCVD). This technique utilizes direct liquid injection of a precursor solution using an ultrasonic nozzle to introduce the precursor vapour into the low-pressure vertical cold-wall reactor. Tantalum (V) ethoxide (C10H25O5Ta) was chosen as alkoxide because it is already an oxygen-containing precursor and its decomposition temperature is low. Films were grown in the temperature range 400–800 °C. Three solution concentrations were tested (1, 2 and 4 vol.%). Experimental results were analysed to determine the growth rate controlling mechanisms and film quality. The highest growth rate was achieved with the most dilute solution and film thickness of 3 μm was achieved with this technology with a growing rate of 8.52 μm/h. The refractive index and dielectric constant of the films increase with the growth in temperature, and as for the growing rate, the 1 vol.% solution leads to the best results. Analysis shows that the morphology and porosity of the films can be controlled by deposition temperature and solution concentration. Pulsed-MOCVD has demonstrated good performance with uniform film thickness and high growth rate.