Formation of compositionally graded multilayer films by discharge gas flow modulation in magnetron sputtering

Abstract

A new method to form compositionally graded multilayer films by using a single deposition source has been developed. In this method, the reactive gas flow rate has been changed periodically to form multilayers. As a result, the composition of the multilayer films obtained by this technique changes periodically without any interrupted interfaces. To form multilayers using this technique, a non-linear relationship between the reactive gas flow rate and the deposition parameters such as deposition rate and reactive gas consumption should be considered because they cause a non-linear relationship between the reactive gas flow rate and the composition distribution towards the film depth of deposited films. Without considering this, the film with a sinusoidal component distribution that is assumed to originate novel properties cannot be obtained. By comparing the oxygen distribution towards the film depth obtained by Auger electron spectroscopy with that calculated from O 2 consumption during film deposition, it was found that oxygen diffused towards the metal-rich underlayers during deposition of oxygen-rich layers. This diffusion makes it difficult to estimate and control film layer composition distribution from deposition parameters. By optimizing the gas flow rate change a TiO x multilayer film with a 5-layered sinusoidal component distribution has been obtained.