Measurement of Thickness Distribution of Molecularly Thin Lubricant Films on Head Sliders Using Ellipsometric Microscopy

Abstract

Lubricant transfer or pickup from a disk to head slider is a crucial issue in designing the head–disk interfaces with a reduced head–disk gap. Observation of lubricant on the slider is difficult with the conventional methods due to their limited lateral resolution. In this paper, nanometer-thick lubricant on a slider was observed by using vertical-objective-based ellipsometric microscopy (VEM). The lubricant thickness was evaluated using a null-ellipsometric method. The thickness measured by VEM agreed fairly well with that by atomic force microscopy. The temporal change in the thickness of a nanometer-thick lubricant film distribution around a read/write element in the slider was successfully observed with a lateral resolution of the order of $1 ~\mu \text{m}$ .