The Influence of Layer Thickness and Deposition Conditions on Structural State of NbN/Cu Multilayer Coatings

Authors O.V. Sobol′1 , A.A. Andreev2 , A.A. Meylekhov1 , А.А. Postelnyk1 , V.A. Stolbovoy2 , I.M. Ryshchenko1, Yu.Ye. Sagaidashnikov1, Zh.V. Kraievska1

1National Technical University «Kharkiv Polytechnic Institute», 2, Kyrpychov Str., Kharkiv, 61002, Ukraine

2National Science Center Kharkov Institute of Physics and Technology, 1, Akademicheskaya Str., Kharkiv, 61108, Ukraine

Issue Volume 11, Year 2019, Number 1
Dates Received 26 December 2018; revised manuscript received 07 February 2019; published online 25 February 2019
Citation O.V. Sobol′, A.A. Andreev, A.A. Meylekhov, et al., J. Nano- Electron. Phys. 11 No 1, 01003 (2019)
PACS Number(s) 64.75.St, 81.07.Bc, 62.25.-g, 61.05.cp, 61.82.Rx
Keywords Vacuum arc, NbN/Cu, Period (2) , Bias potential (2) , Phase composition (3) , Structure (105) , Solid solution (6) .

The influence of the main physical and technological factors of structural engineering (layer thickness, nitrogen atmosphere pressure and bias potential) on the structural-phase state of the NbN/Cu coatings was studied. It was established that with an increase in the thickness of niobium nitride layers from 8 to 40 nm (in the NbN/Cu multilayer composition), the phase composition changes from the metastable d-NbN (cubic crystal lattice, NaCl structural type) to the equilibrium ε-NbN phase with a hexagonal crystal lattice. At low pressure PN = 7·10 – 4 Torr in thin layers (about 8 nm thick), regardless of the Ub, the d-NbN phase is formed. The reason for the stabilization of this phase can be the uniformity of the metallic fcc crystal lattice of the δ-NbN phase with the Cu crystal lattice. As the pressure increases from РN = 7·10 – 4 Torr to 3·10 – 3 Torr, a more equilibrium ε-NbN phase with a hexagonal crystal lattice is formed. An increase in the bias potential during deposition from – 50 V to – 200 V mainly affects the change in the preferred orientation of crystallite growth. In thin layers of the d-NbN phase (about 8 nm), a crystallite texture with the [100] axis is formed. In layers with a thickness of 40-120 nm, crystallites of the e-NbN phase are predominantly formed with a hexagonal (004) plane parallel to the growth plane. At the greatest layer thickness (more than 250 nm), the e-NbN phase crystallites are predominantly formed with a (110) hexagonal lattice plane parallel to the growth plane. The results obtained show great potential for structural engineering in niobium nitride when it is used as a constituent layer of the NbN/Cu multilayer periodic system.

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