Sputtering by inverted magnetrons: influence on the texture and residual stresses in four layer Ta/W/Ta/W coatings

The aim of the study is to examine the possibilities of sputtering of multilayer coatings at a high rate of deposition on products of complex shape using inverted magnetrons. The formation of texture and residual stresses in magnetron four-layer Ta/W/Ta/W coatings deposited at voltages from 0 to –200 V on cylindrical and flat copper substrates imitating elements of the surface of complex shape products was evaluated using the X-ray method of inverse pole figures and the sin²Ψ method. The patterns of texture formation in coatings depend mainly on the bias voltage on the substrate (U_s), while at U_s = –200 V they differ for W and Ta layers. At U_s = –100 V, the epitaxial mechanism of texture formation is realized. In the case of a cylindrical substrate, this leads to intense texture (111) of all four layers. In the case of a flat substrate, this can lead to the formation of a single-crystal texture (111) in all layers with a texture maximum width of 12°–14°. The presence of a single-crystal (111) tantalum texture corresponds to the maximum Young moduli and, accordingly, the interatomic bonding forces normal to the coating plane. This suggests that multilayer coatings with an external Ta layer have high tribological characteristics. Increasing the voltage on a flat substrate from 0 to –200 V leads to an increase in residual compressive stresses from 0.5 to 2.7 GPa for the four-layer coating under study.

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