Structures and properties of Cu-W composite thin films deposited by Co-sputtering of combination targets
Cu-W composite thin films were prepared on single-crystal silicon and polyimide substrates by magnetron co-sputtering method with embedded combination targets. The composition, structure and surface morphology of Cu-W composite thin films were analyzed and characterized using energy dispersive spectrometer, X-ray diffractometer, scanning electron microscope and atomic force micro-scope, respectively. The yield strength σ0.2, critical strain of crack initiation εc, micro hardness H and electrical resistivity ρ of composite thin films were tested using micro force testing system, nano-inden-tation instrument and four-point probe, respectively. The results show that the W content of the compos-ite thin films can be effectively controlled by adjusting the area ratio of the W target in the annular sput-tering etching zone of the combination targets. As the proportion of W target area increases from 6％ to 30％, the W content of Cu-W composite thin films increases from 2.6 at.％ to 16.9 at.％. The solid solu-bility of W in Cu extends and with the presence of face centered cubic (fcc) Cu(W) metastable solid so-lution in the composite films. As the W content of the composite films increases, the solid solubility of W in Cu increases from 1.7 at.％ W to 10 at.％ W. The average grain of the composite films decreases from 32 nm to 16 nm, and the surface smoothness improves. When the W content increases, the yield strength σ0.2, microhardness H, and electrical resistivity ρ of the composite films increase, while the critical strain of crack initiation εc decreases.
combination targetsco-sputteringCu-W composite thin films
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