Atomic layer deposition of tantalum oxide thin films using the precursor tert-butylimido-tris-ethylmethylamido-tantalum and water: Process characteristics and film properties

Post-deposition annealing at 800 °C in nitrogen resulted in the crystallization of the Ta2O5 films, which is also accompanied by an increase in film density and refractive index. Moreover, the crystallized films exhibit an enhanced dielectric constant of 48 ± 2. Electrical measurements revealed the growth of an interfacial layer with an equivalent oxide thickness of around 2.4 nm due to the 800 °C annealing. While this interfacial layer degrades the effective permittivity of the dielectric (e.g. 20.5 ± 0.5 for a 20 nm Ta2O5 film), it also causes a reduction of the leakage currents by more than three orders of magnitude (e.g. to 1·10− 7 A/cm2 for a 20 nm Ta2O5 film).