Abstract
The atomic layer deposition (ALD) growth of Ta2O5 thin films was investigated using tert-butylimidotris(3,5-di-tert-butylpyrazolato)tantalum and ozone as precursors at deposition temperatures between 250 and 500 °C. The process provided uniform films and exhibited a large ALD window between 300 and 450 °C, in which a constant growth rate of 0.30 Å/cycle was observed. Surface-limited growth was confirmed at 325 °C, as evidenced by a constant growth rate with increasing precursor dose as delivered by longer pulse lengths. Furthermore, the thickness of films deposited at 325 °C varied linearly with the number of deposition cycles, which demonstrates good thickness control typical of ALD growth. The process provided stoichiometric Ta2O5 films with carbon, hydrogen, and nitrogen levels of ≤ 1.0 ≤ 1.9 and ≤ 0.9 atom %, respectively, within the ALD temperature window as determined by time-of-flight elastic recoil detection analysis. X-ray photoelectron spectroscopy measurements were consistent with the presence of Ta(V) and a stoichiometry of Ta2O5, with impurity elements below detection limits. All films were amorphous as deposited as determined by X-ray diffraction.
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