Flying height measurement considering the effects of the slider-disk interaction

As technology moves to a mechanical head-disk spacing of 4-8 nm for the recording density beyond 100 Gb/in², new testing methodology becomes necessary to achieve both high sensitivity in flying height measurement and accurate characterization of slider-lube-disk interaction. This paper reports a polarization intensity interferometer which retains high sensitivity in fly-height measurement even when the slider-disk spacing is down to nanometer level. The setup can also study the effect of slider-lube-disk interaction on the flying performance of the slider. This is achieved by covering the commercial glass disk substrate with a layer of carbon overcoat and a layer of lubricant which are same as those used in the actual disk media. Both simulation and experimental investigations were conducted and the results agree well with each other. Results also indicate that it is important to take the slider-disk interaction into account in the flying height measurement of the nanometer spaced head-disk interface