M. J. Sowa, Y. Yemane; J. Zhang, J. C. Palmstrom, L. Ju, N. Strandwitz, F. B. Prinz, J. Provine, “Plasma-enhanced atomic layer deposition of superconducting niobium nitride,” JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, Volume 35, Issue 1, Article 01B143, Jan-Feb 2017.
Thin films of niobium nitride are useful for their physical, chemical, and electrical properties. NbN superconducting properties have been utilized in a wide range of applications. Plasma-enhanced atomic layer deposition (PEALD) of NbN with (t-butylimido) tris(diethylamido) niobium(V) and remote hydrogen/nitrogen plasmas has been investigated. Deposited filmproperties have been studied as a function of substrate temperature (100–300 degrees Celsius) plasma power (150–300 W), and hydrogen flow rate (10–80 sccm). PEALD NbN films were characterized with spectroscopic ellipsometry (thickness, optical properties), four point probe (resistivity), x-ray photoelectron spectroscopy (composition), x-ray reflectivity (density and thickness), x-ray diffraction (crystallinity), and superconductivity measurements. Film composition varied with deposition conditions, but larger cubic NbN crystallites and increased film density at higher substrate temperatures and hydrogen flow rates lead to room temperature resistivity values as low as 173 μΩ cm and superconductivity critical temperatures as high as 13.7 K.