New thin film fabrication technique using a substrate excited by SAW

A novel thin-film fabrication technique which uses a surface phonon mode substrate excited by surface acoustic waves (SAW) to control the morphology of very thin films is presented. Permalloy films and Co-Cr-Ta films of 300-Å thickness were prepared by DC magnetron sputtering onto LiNbO₃ single-crystal substrate excited by SAW. By scanning electron microscopy and scanning tunneling microscopy observations, the structure of films was found to be drastically changed by SAW excitations as a function of excited amplitude. Especially at the critical excitation voltage, the film structure consists of a homogeneous grain form, and a very fine grain size is realized. In the Co-Cr-Ta sputtered films fabricated at this critical SAW excitation voltage of 8 V, H_c takes a minimum value of about 5 Oe, which is two orders lower than that of films fabricated without SAW excitation. The Mo-Permalloy films fabricated at this voltage are stress-free and have excellent soft magnetic properties