Platinum-coated probes sliding at up to 100 mm s-1 against coated silicon wafers for AFM probe-based recording technology

One of the new alternative information storage technologies being researched is based on the probe-based recording technique. In one technique, a phase-change medium is used, and the phase change is accomplished by applying either a high or low magnitude of current which heats the interface to different temperatures. Tip wear is a serious concern. For wear protection of the phase-change chalcogenide medium with a silicon substrate, diamond-like carbon (DLC) film with various lubricant overcoats was deposited on the recording layer surface. Nanowear properties of platinum (Pt)-coated probes with high electrical conductivity have been investigated in sliding against the coated medium using an atomic force microscope (AFM). A silicon grating sample and software to deconvolute tip shape were used to characterize the change in the tip shape and evaluate the tip radius and its wear volume. The nanowear experiments were performed at sliding velocities ranging from 0.1 to 100 mm s-1. Pt-coated tips on the lubricant-coated DLC film surfaces showed less sensitivity to the velocity and the load as compared to the unlubricated DLC film surfaces. In wear life threshold experiments, the threshold reaches a smaller sliding distance at higher loads. In high-temperature experiments at 80 deg. C, the wear rate is higher compared to that at 20 deg. C. The results suggest that the wear mechanism at low velocity appears to be primarily adhesive and abrasive. At high velocity, an additional wear mechanism of the tribochemical reaction is important