A method for determining ultrathin DLC film thickness by spectroscopic ellipsometry

Abstract

The accurate measurement of ultrathin DLC overcoat thickness becomes a key factor in the research and fabrication of advanced magnetic recording heads and media with the ever-decreasing head-media spacing. Spectroscopic ellipsometry can meet this requirement when the suitable measurement method is adopted. For ultrathin DLC film, there is the strong correlation between its optical constants and thickness, which makes ellipsometry measurement difficult to yield a unique and accurate solution. In this study, we adopt a combined analytical method to determine ultrathin DLC films with a thickness range of 10-50 Å . The uniqueness and accuracy of the measured thickness are verified by Uniqueness Test tool and X-ray reflectivity (XRR), respectively. The results show that the adopted method is able to uniquely and accurately measure the thickness of ultrathin DLC film. This method is expected to be of value for thickness measurement of other ultrathin dielectric or metallic films. © Springer-Verlag 2012.