The properties of W–C:H films deposited by reactive rf sputtering

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Abstract
Tungsten-containing amorphous hydrogenated carbon (W–C:H) films were prepared on silicon substrates by reactive rf sputtering (13.56 MHz). Elastic recoil detection (ERD) and Rutherford backscattering (RBS) of MeV He+ ions have been performed to determine the hydrogen concentration and mass density of the films, respectively. The mechanical properties, i.e., the microhardness, Young's modulus, and the adhesion on substrates, have been studied by depth-sensing indentation equipment (nanoindenter) and a scratch tester with an acoustic emission (AE) detector, respectively. The electric conductivity of the films was also measured. The results show that these properties depend mainly on the tungsten concentration. X-ray diffraction suggests that the W–C:H films consist of an a–C: H polymeric matrix with WC1−x(β) particles embedded. With increasing tungsten concentration the films change from polymeric a–C:H dominant to crystalline WC1−x(β) dominant W–C:H, resulting in different film properties.