Ultra-thin tetrahedral amorphous carbon film as slider overcoat for high areal density magnetic recording

Abstract

Abstract Areal density in magnetic recording has been increasing at a phenomenal rate over the past 10 years. In order to achieve 10 Gb/in 2 areal density and more, magnetic spacing between the disk and head must be of the order of 35 nm or less, which requires 5 nm or less overcoats on both the media and recording head air bearing surface (ABS). These overcoats act as protective coatings against corrosion of magnetic alloys as well as wear which may occur when the slider contacts the rigid disk during turn-on or shutdown of disk drive. Tetrahedral amorphous carbon (ta-C) films of 1.5–7.0 nm thickness have been deposited on both Si wafers and recording sliders by a filtered cathodic arc (FCA) system. The coatings were analyzed by Raman, cross-section TEM, EELS, contact angle and Tencor Flexus Stress Analyzer in order to characterize film structure, thickness and uniformity, sp 3 content, density, surface energy and stress. Macro-particle contamination was significantly reduced by process optimization and characterized by an acid etch corrosion resistance test. The effect of carbon interactions with magnetic layers and causing a magnetic 'dead-layer' were also investigated with a B-H loop tester and high resolution cross-section TEM. Slider/HGA level tests were conducted in order to evaluate head tribological performance at the head/disk interface (HDI) and corrosion resistance. These were conducted by Contact Start/Stop (CSS) test and Battelle/Acid etch tests. We conclude that the sub-5 nm overcoats prepared by FCA are a viable candidate for future high areal density giant magnetoresistance (GMR) slider ABS applications.