Corrosion Measurements on Thin-Film Disks Using Optical Surface Analysis

The diminishing thickness of the carbon overcoat layer on a thin-film magnetic storage disk results in a greater susceptibility to corrosion and a need to move toward a fast and reliable corrosion analysis technique. A new method for quantifying corrosion levels on thin-film disks has been developed using an optical surface analyzer (OSA). High- and low-corrosion-level disks were used to develop and verify the necessary algorithms for surface analysis. The results from OSA were referenced to established methods such as scanning electron microscopy (SEM), scanning Auger microscopy (SAM), and ion chromatography (IC) wash techniques. A reliable method for identifying nickel- and cobalt-based corrosion and for separating corrosion from debris was developed. The OSA proved to be a faster and more sensitive corrosion-detection technique than SAM.