Radical Enhanced Atomic Layer Deposition of Titanium Dioxide

Abstract

AbstractTitanium dioxide films are grown with radical‐enhanced atomic layer deposition (RE‐ALD) from titanium isopropoxide and oxygen radicals at between 50 and 300 °C on silicon, glass, platinum, and RuO2 surfaces. Additionally, the films are grown on polymers and natural fibers at 50 °C. The oxygen radicals are produced by dissociating molecular oxygen with a remote microwave plasma discharge. Purified argon is used as the carrier and purge gas. Growth rate saturation and conformal growth are observed, and thus the film growth in the ALD mode was proven. The saturated growth rate is 0.19 nm per cycle at 50 °C, with an overall cycle time of 11 s. The film grown at 50 °C has a dielectric constant of 20, and undergoes catastrophic breakdown at 0.6 MV cm–1 electric field. It contains 13 at.‐% hydrogen and 4 at.‐% carbon. As the deposition temperature is increased to 250 °C, the impurity contents decrease to 0.5 at.‐% for hydrogen and 0.4 at.‐% for carbon. The film density and refractive index are 3.2 g cm–3 and 2.2, respectively, for a film deposited at 50 °C, and increases to 3.8 g cm–3 and 2.4, respectively, for a film deposited at 250 °C. All the films grown below 250 °C are amorphous according to X‐ray diffraction (XRD).