Preparation of Copper Thin Films Utilizing Unbalanced Magnetron Sputtering Assisted by Inductively Coupled Plasma

Abstract

  The effect of an external magnetic flux on the substrate current and structural properties of Cu thin films was investigated. These films were prepared by magnetron sputtering with an external solenoid coil arrangement assisted by inductively coupled plasma (ICP). When unbalanced magnetron sputtering with an external magnetic flux of 4 mT assisted by ICP was used, the current flowing into the substrate due to Ar⁺ ions and sputtered Cu⁺ ions was 44 mA, which is about 2.3 times greater than that of a conventional magnetron sputtering system. From X-ray diffraction (XRD) observations it was found that the intensities of the Cu(111) and Cu(200) peaks vary significantly with external magnetic flux. The intensity of the XRD peak for Cu(111) increased and that for Cu(200) decreased when the external magnetic flux was increased from 0 mT to 4 mT. Atomic force microscope images of thin films deposited at different external magnetic fluxes show that the average surface grain size at 0 mT is 38.4 nm and that at 4 mT is 85.4 nm.