Investigation of niobium nitride and oxy-nitride films grown by MOCVD

Niobium nitride (NbN) and niobium oxy-nitride (NbOxNy) thin films were grown by metalorganic chemical vapor deposition (MOCVD) on Si(100) and Si(111) substrates using [Nb(NtBu)(NMe2){C(NiPr)2(NMe2)}2] [NB; tBu=(CH3)3C; Me=CH3; iPr=(CH3)2CH] as a simultaneous Nb and N precursor. While NbN films were synthesized under a pure N2 atmosphere, NbOxNy films were synthesized under N2–O2 flow (N2:O2=1–5) in the temperature range 400–600 °C, as well as by NbN deposition followed by ex-situ thermal treatments under flowing O2 at 400–600 °C. The samples were subjected to a multi-technique characterization in order to elucidate the interplay between their structure, morphology and composition and the adopted processing parameters. Particular attentionwas devoted to the presence of Nb–NandNb–O–N phases and their distribution in the films, aswell as to surface oxidation phenomena. For the first time, niobiumoxy-nitride coatingswere obtained by CVD starting from the above precursor compound, with growth rates up to 270 Å/min on Si(111) at 600°C. The films were characterized by a columnar-like/globular morphologywhen supported on Si(100)/Si(111) and revealed a higher crystallinity on the latter substrate. Surface and in-depth compositional analyses evidenced a limited carbon contamination and the Co-existence of niobiumnitride, NbON and Nb2O5. Inparticular, the presence of the latter in the outermost sample layers was explained by oxidation phenomena occurring upon contact with the outer atmosphere.