Effect of tilted closed-field magnetron design on the microstructure and mechanical properties of TiZrNbTaN coatings

Abstract

A common design of sputtering systems is to integrate many magnetron sources in a tilted closed-field configuration, which can drastically affect the magnetic field in the chamber and thus plasma characteristics. To study this effect explicitly, multicomponent TiZrNbTaN coatings were deposited at room temperature using direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) with different substrate biases. The coatings were characterized by x-ray diffraction, scanning electron microscopy, nano-indentation, and energy dispersive x-ray spectroscopy. Magnetic field simulations revealed ten times higher magnetic field strengths at the substrate in single-magnetron configuration when compared to the closed-field. As a result, the substrate ion current increased ∼3 and 1.8 times for DCMS and HiPIMS, respectively. The film microstructure changed with the discharge type, in that DCMS coatings showed large sized columnar structures and HiPIMS coatings show globular nanosized structures with (111) orientation with a closed-field design. Coatings deposited from a single source showed dense columnar structures irrespective of the discharge type and developed (200) orientation only with HiPIMS. Coatings deposited with closed-field design by DCMS had low stress (0.8 to −1 GPa) and hardness in the range from 13 to 18 GPa. Use of HiPIMS resulted in higher stress (−3.6 to −4.3 GPa) and hardness (26–29 GPa). For coatings deposited with single source by DCMS, the stress (−0.15 to −3.7 GPa) and hardness were higher (18–26 GPa) than for coatings grown in the closed-field design. With HiPIMS and single source, the stress was in the range of −2.3 to −4.2 GPa with a ∼6% drop in the hardness (24–27 GPa).