Timothee Blanquart

Atomic layer deposition and characterization of vanadium oxide thin films

In this study, VOx films were grown by atomic layer deposition (ALD) using V(NEtMe)4 as the vanadium precursor and either ozone or water as the oxygen source. V(NEtMe)4 is liquid at room temperature and shows good evaporation properties. The growth was investigated at deposition temperatures from as low as 75 °C, up to 250 °C. When using water as the oxygen source, a region of constant growth rate (ca. 0.8 A/cycle) was observed between 125 and 200 °C, with the ozone process the growth rate was significantly lower (0.31–0.34 A/cycle). The effect of the process conditions and post-deposition annealing on the film structure was investigated. By varying the atmosphere under which the films were annealed, it was possible to preferably form either VO2 or V2O5. Atomic force microscopy revealed that the films were smooth (rms < 0.5 nm) and uniform. The composition and stoichiometry of the films were determined by X-ray photoelectron spectroscopy. Conformal deposition was achieved in demanding high aspect ratio structure.

High-performance imido–amido precursor for the atomic layer deposition of Ta2O5

The atomic layer deposition of Ta2O5?thin films was studied using a novel imido?amido precursor tBuN = Ta(NEt2)3. This precursor is liquid at room temperature, possesses good volatility and is reactive toward both water and ozone as the oxygen sources. The deposition temperature was varied from 125 to 475 ?C. Saturated film growth was confirmed at 325 ?C for both water and ozone processes, and a region of constant growth rate was observed between 125 and 350 ?C when using ozone as the oxygen source. All the films were amorphous in the as-deposited state and crystallized at around 700 ?C into orthorhombic Ta2O5, regardless of the applied oxygen source. X-ray photoelectron spectroscopy demonstrated high purity of the films deposited at temperatures higher than 225 ?C. Atomic force microscopy revealed that the films were smooth (rms < 0.3 nm) and uniform. The films exhibited permittivity values of ?25 and low leakage current.

Influence of growth and annealing temperatures on the electrical properties of Nb2O5-based MIM capacitors

Metal?insulator?metal (MIM) capacitors were grown by atomic layer deposition using tBuN = Nb(NEt2)3?and ozone as niobium and oxygen precursors, respectively. Three different deposition temperatures were used and some of the films were postdeposition annealed. The permittivity values obtained reached a value of about 50 for the films crystallized after annealing at temperatures higher than 500 ?C. However, the leakage current values for the crystalline films were higher than those in the case of amorphous films.