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.