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The atomic layer deposition (ALD) growth of Ta 2 O 5 films was demonstrated using Ta(NtBu)-(iPrNC(Me)NiPr) 2 (NMe 2 ) and water with substrate temperatures between 225 and 400 °C. At 325 °C, self-limited growth was demonstrated with Ta(NtBu)(iPrNC(Me)NiPr) 2 (NMe 2 ) and water pulse lengths of g0.5 s. An ALD window was observed between 275 and 350 °C, with a growth rate of 0.28 A ˚/cycle. The growth rates were 0.33 and 0.37 A ˚/cycle at 250 and 225 °C, respectively. At 375 and 400 °C the growth rate increased slightly to 0.31 A ˚/cycle, and precursor thermal decomposition may contribute to growth at these temperatures. In a series of films deposited at 325 °C, the film thickness increased linearly with the number of deposition cycles. X-ray photoelectron spectroscopy of films deposited at 300 and 350 °C revealed stoichiometric Ta 2 O 5 with carbon and nitrogen levels below the detection limits. The films were amorphous as deposited, but annealing at 700 °C in dry air resulted in crystallization of hexagonal δ-Ta 2 O 5 . Atomic force microscopy found root-mean-square surface roughnesses of 0.6-0.7 nm for 45 nm thick films deposited at 300 and 350 °C. The index of refraction of films grown at 325 °C was determined to be 2.12-2.16 at 633 nm using ellipsometry.

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