Structures and properties of copper thin films prepared by ion beam assisted deposition

Abstract

Copper thin films were prepared by ion beam assisted deposition (IBAD) technique, to perform a systematic investigation on the effect of ion bombardment with respect to the structural modification and the electrical properties of the films. The films were deposited under the argon ion bombardment with energies between 75 and 675 eV. The atomic density of the films deposited on Si substrates strongly depeded on the deposition rate rather than the energy or the current on beams. Under the same deposition rate, the atomic density gradually decreased with an increase of the ion energy. As for the films on SiO 2 substrates, however, the atomic densities were improved with increasing the arrival rate ratio and the ion energy. X-ray diffraction analysis showed that the film structures were modified to have (111) preferred orientation and the films had larger vertical grain sizes with increasing the arrival rate ratio and the ion energy. These modifications were also most significant for the films deposited on SiO 2 substrates. Electrical resistivity strongly depended on the argon concentration in the films, while less depended on the crystallinity. The increase of the electrical resistivity for the films on Si substrates was larger than those on SiO 2 substrates. It was suggested that the lateral grain size, which dominates the electrical resistivity, reduced with an increase of the arrival rate ratio and the ion energy. The results could be summarized as the structure of the films prepared by IBAD technique became columnar and the electrical resistivity had a strong correlation with the argon concentration.