Niobium (tert-amylimido) tris(tert-butoxide) Nb(=N-tAmyl)(OtBu)3 (and for comparison Nb(=N-tBu)(NEt2)3, Nb(=N-tBu)(NMeEt)3, ) has een applied as Nb precursor
for the deposition of Nb2O5 thin layers by ALD at temperatures from 150 to 375°C. Nb(=N-tAmyl)(OtBu)3 (as well as both imide-amides) are liquid at RT, have good volatility, and are reactive to both H2O and O3 as oxygen sources. Nb(=N-tAmyl)(OtBu)3 exhibited limited thermal stability, leading to non-achivement of saturative ALD growth mode , whereas tBuN═Nb(NEt2)3 and tBuN═Nb(NMeEt)3 (with
both oxygen sources) demonstrated ALD-type saturative growth modes at 275°C and constant growth rates at 150 and 325 °C. Layers gron with Nb(=N-tAmyl)(OtBu)3 as well as other precursors (with all O sources) were amorphous as-deposited, but crystallized at 525-575 °C. The deposited
Nb2O5 layers had high purity (by TOF-ERDA), were smooth and uniform (according to AFM) and demonstrated promising dielectric characteristics (permittivity values up to 60).
[i]
[i] T. Blanquart, J. Niinistö, M. Heikkilä, T. Sajavaara, K. Kukli, E. Puukilainen, Ch. Xu, W. Hunks, M. Ritala, M. Leskelä, Chem. Mater., 2012, 24, 6, 975-980, « Evaluation and Comparison of Novel Precursors for Atomic Layer Deposition of Nb2O5 Thin Films », https://doi.org/10.1021/cm2026812, https://pubs.acs.org/doi/abs/10.1021/cm2026812