Platinum-coated probes sliding at up to100 mm s−1 against coated silicon wafers for AFM probe-based recording technology

Abstract

One of the new alternative information storage technologies being researched is based onthe probe-based recording technique. In one technique, a phase-change medium is used, andthe phase change is accomplished by applying either a high or low magnitude ofcurrent which heats the interface to different temperatures. Tip wear is a seriousconcern. For wear protection of the phase-change chalcogenide medium with asilicon substrate, diamond-like carbon (DLC) film with various lubricant overcoatswas deposited on the recording layer surface. Nanowear properties of platinum(Pt)-coated probes with high electrical conductivity have been investigated in slidingagainst the coated medium using an atomic force microscope (AFM). A silicongrating sample and software to deconvolute tip shape were used to characterize thechange in the tip shape and evaluate the tip radius and its wear volume. Thenanowear experiments were performed at sliding velocities ranging from 0.1 to100 mm s−1. Pt-coated tips on the lubricant-coated DLC film surfaces showed lesssensitivity to the velocity and the load as compared to the unlubricated DLCfilm surfaces. In wear life threshold experiments, the threshold reaches asmaller sliding distance at higher loads. In high-temperature experiments at80 °C, the wear rate is higher compared to that at20 °C. The results suggest that the wear mechanism at low velocity appears to be primarilyadhesive and abrasive. At high velocity, an additional wear mechanism of the tribochemicalreaction is important.