Capacitance methods in head-disk interface studies

Abstract

The continued drive toward contact recording and low flying in the hard-disk industry leads to ever-increasing demands for characterization of the head-disk interface. Herein are discussed three new applications for precise capacitance measurements between sliders and disks: 1. The slider-disk capacitance is shown to be a nondestructive measurement of stiction forces. 2. The capacitance-stripe technique is discussed as a way to measure fly-height, pitch, and crown of sliders. 3. A new implementation of the capacitance microscope is introduced which uses a special slider to profile a hard-disk spinning at up to 20 m/s with 20 μm lateral resolution and 1 nm vertical resolution. Most of the paper is devoted to the capacitance microscope, whose chief advantage over conventional profilometry is that it allows continuous observation of a disk under a flying interface in-situ. Results from a reliability test are presented to illustrate application of the capacitance microscope. Correlation between magnetic signal loss and physical damage that occurs during this reliability test provides further insight into disk failure. © 1993 IEEE