Dimensional features and mechanisms of growth of magnetron nanofilms of Tantalum nitride during high-frequency reactive formation

Purpose of research. Nanostructuring in magnetron nanofilms of Tantalum nitride by high-frequency magnetron sputtering.
Methods. High–frequency magnetron sputtering on a silicon substrate was carried out depending on the change in the time control parameter t = 1800 - 3600 C. A Tantalum target sprayed at a fixed T = 140°C, P = 300 W, pressure Ar 1.0 Pa was used. The surfaces of the substrates were ion-cleaned for 120 s with a current of 60 mA. The increase in film thickness was achieved by changing the time control parameter t. Nanoscale characterization of the obtained tantalum nitride nanofilms was carried out using atomic force microscopy, digital holographic microscopy, and X-ray phase analysis. Based on the results of statistical AFM image processing, the analysis of autocorrelation functions and changes in fractal dimensions determined by the cube method was performed.
Results. The nanofilm thicknesses were measured and the growth rates of nanofilms were calculated using the precision step method on AFM and CGM images, and their linear increase as a function of time t was proved. According to the XRD data, the formation of the hexagonal hex-Ta2N phase in thin layers and the transition to the dominance of cubic fcc-TaN with increasing thickness have been established. Evolutionary processes of surface morphology were observed with the transition from an isotropic fine-grained structure to a pronounced columnar one, which was confirmed by a decrease in fractal dimension and an increase in the lengths of the autocorrelation function.
Conclusion. In magnetron nanofilms of tantalum nitride deposited by the high-frequency method, a phase transition from the hexagonal hex-Ta2N phase in thin layers to the cubic fcc-TaN phase, starting from a critical thickness, was detected. A decrease in the fractal dimension and an increase in the lengths of the autocorrelation function indicated the evolution of the surface morphology from isotropically fine-grained to pronounced columnar. 

1. Elangovan T., Murugeshan S., Mangalaraj D., Kuppusami P., Khan Shabhana, Sudha C., Ganesan V., Divakar R., Mohandas E.. Synthesis and high temperature XRD studies of tantalum nitride thin films prepared by reactive pulsed dc magnetron sputtering. Journal of Alloys and Compounds. 2011;509(22):6400-6407. https://doi.org/10.1016/j.jallcom.2011.03.067.

2. Bernoulli D., Müller U., Schwarzenberger M., Hauert R., Spolenak R.. Magnetron sputter deposited tantalum and tantalum nitride thin films: An analysis of phase, hardness and composition. Thin Solid Films. 2013;548:157-161. https://doi.org/10.1016/j.tsf.2013.09.055.

3. Firouzabadi S.S., Naderi M. Assistant Professor, Dehghani K. Associate Professor, Mahboubi F. Associate Professor. Effect of nitrogen flow ratio on nano-mechanical properties of tantalum nitride thin film. Journal of Alloys and Compounds. 2017;719:63-70. https://doi.org/10.1016/j.jallcom.2017.05.159.

4. Y.H. Yang, D.J. Chen, F.B. Wu. Microstructure, hardness, and wear resistance of sputtering TaN coating by controlling RF input power. Surface and Coatings Technology. 2016;303(A):32–40. https://doi.org/10.1016/j.surfcoat.2016.03.034.

5. Zaman A., Meletis E.I. Microstructure and mechanical properties of TaN thin films prepared by reactive magnetron sputtering. Coatings. 2017;7(12):209. https://doi.org/10.3390/coatings7120209.

6. Tajima H., Shiobara N., Katsumata H., Uekusa S. Properties of TaN Films for ULSIs Prepared by Reactive Sputter Deposition. Journal of Surface Analysis. 2011;17(3):247-251. https://doi:10.1384/jsa.17.247.

7. Serna-Manrique M. D. et al. Growth Mechanisms of TaN Thin Films Produced by DC Magnetron Sputtering on 304 Steel Substrates and Their Influence on the Corrosion Resistance. Coatings. 2022;12(7):979. https://doi.org/10.3390/coatings12070979.

8. Nie H.B., Xu S.Y., Wang S.J., You L.P., Yang Z., Ong C.K., Li J., Liew T.Y.F. Structural and electrical properties of tantalum nitride thin films fabricated by using reactive radio-frequency magnetron sputtering. Appl. Phys. A 73. 2001;73:229–236. https://doi.org/10.1007/s003390000691.

9. Baik SI., Kim YW. Microstructural evolution of tantalum nitride thin films synthesized by inductively coupled plasma sputtering. Applied Microscopy. 2020;50(7). https://doi.org/10.1186/s42649-020-00026-7.

10. Lei Weiwei, Liu Dan, Shen Longhai, Zhang Jian, Zhu Pinwen, Cui Qiliang, Zou Guangtian. Growth and characterization of single-phase metastable tantalum nitride nanocrystals by dc arc discharge. Journal of Crystal Growth. 2007;306(2):413–417. https://doi.org/10.1016/j.jcrysgro.2007.05.010.

11. Zhou Y.Z., Volek A., Green N.R. Mechanism of competitive grain growth in directional solidification of a nickel-base superalloy. Acta Materialia. 2008;56(11):2631-2637. https://doi.org/10.1016/j.actamat.2008.02.022.

12. Nieto R., Fernández J., Martínez A. Synthesis of superconductive TaN thin films by reactive DC sputtering. J. Electron. Mater. 2022;51:4649–4658. https://doi.org/10.1007/s11664-022-09721-5.

13. Kuzmenko A.P., Kashkin I.S., Kolpakov A.I., Zhakin A.I., Yemelyanov V.M. Structural and morphological features of magnetron nanofilms of TaN with different thicknesses. Izvestiya Yugo-Zapadnogo gosudarstvennogo universiteta. Seriya: Tekhnika i tekhnologii = Proceedings of the Southwest State University. Series: Engineering and Technology. 2024;14(3):147-164. (In Russ.) https://doi.org/10.21869/2223-1528-2024-14-3-147-164

14. Bernoulli D., Müller U., Schwarzenberger M., Hauert R., Spolenak R. Magnetron sputter deposited tantalum and tantalum nitride thin films: An analysis of phase, hardness and composition. Thin Solid Films. 2013;548:157-161. https://doi.org/10.1016/j.tsf.2013.09.055.

15. Hu X.-Y., Li D.-W., Zhang L. et al. Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates. Coatings. 2021;11(8):937. https://doi.org/10.3390/coatings11080937.

16. Kuzmenko A. P., Gusev E. O., Rodionov V. V., Sizov A. S., Mirgorod Yu.A., Tan Myo Ming. Structural and morphological features of magnetron HfN nanofilms with different thicknesses. Izvestiya Yugo-Zapadnogo gosudarstvennogo universiteta. Seriya: Tekhnika i tekhnologii = Proceedings of the Southwest State University. Series: Engineering and Technology. 2022;12(4):110-123. (In Russ.) https://doi.org/10.21869/2223-1528-2022-12-4-110-123.

17. Zaman A., Shen Y., Meletis E.I. Microstructure and Mechanical Property Investigation of TaSiN Thin Films Deposited by Reactive Magnetron Sputtering. Coatings. 2019;9(5):338. https://doi.org/10.3390/coatings9050338.

18. Alishahi M., Mahboubi F., Mousavi Khoiea S.M., Apariciob M., Lopez-Elvirac E., Méndezc J., Gagoc R. Structural properties and corrosion resistance of tantalum nitride coatings produced by reactive DC magnetron sputtering. RSC Advances. 2016;6(92):89061-89072. https://doi.org/10.1039/C6RA17869C.

19. Lou Z., Yang Y., Wang Y., Qin C., Liang R., Wang Y., Ye Z., Zhu L. LaCl3 flux mediated Ta3N5 planar photoanode for solar water oxidation. Chemical Engineering Journal. 2020;396. https://doi.org/10.1016/j.cej.2020.125161.

20. Ataie S.A., Keshtmand R., Zamani-Meymian M. R. Nano-mechanical properties of Cr-Zr-Nb-N medium entropy alloy films produced by reactive sputtering. International Journal of Refractory Metals and Hard Materials. 2023;110. https://doi.org/10.1016/j.ijrmhm.2022.106006.

21. Seifried F., Leiste H., Schwaiger R., Ulrich S., Seifert H. J., Stueber M. Structure, morphology and selected mechanical properties of magnetron sputtered (Mo, Ta, Nb) thin films on NiTi shape memory alloys. Surface and Coatings Technology. 2018;347:379–389. https://doi.org/10.1016/j.surfcoat.2018.05.014.

22. Belyaev B. A., Izotov A.V., Solovyov P. N. Investigation of the growth process and analysis of the structure of thin, obliquely deposited films. Izvestiya Vuzov. Fizika = Izvestiya Vuzov. Physics. 2016;59(2):120-125. (In Russ.)

23. Das A., Yadav R.P., Chawla V., Kumar S., Talu S., Pinto E. P. [et al.] Analyzing the surface dynamics of titanium thin films using fractal and multifractal geometry. Materials Today Communications. 2021;27. https://doi.org/10.1016/j.mtcomm.2021.102385.

24. Necas D., Klapetek P. One-dimensional autocorrelation and power spectrum density functions of irregular regions. Ultramicroscopy. 2013;124:13-19. https://doi.org/10.1016/j.ultramic.2012.08.002.