In Situ Slider-to-Disk Spacing on a Nanometer Scale Controlled by Microheater-Induced Slider Deformations

Air-bearing sliders carrying the read and write elements in today's hard-disk drives fly above the spinning magnetic disks at very close range. It is crucial for the performance as well as the reliability of the hard disk drive to maintain precisely the optimal distance (flying height) between the disk and the read/write elements. With continuously increasing recording densities the flying height is decreasing and will be less than ten nanometers in the next few years. This paper discusses the feasibility of thin-film microresistors integrated into the air-bearing surface of standard sliders for in situ flying-height control. Microresistor loops can be realized in only a few fabrication steps, which can be added to a standard slider manufacturing process. The powered microresistor transfers thermal energy into the slider, leading to deformations of its air-bearing surface. As a consequence of such deformations, a variation of the flying height was observed. The polarity of the actuation, towards or away from the spinning disk, can be defined by the microresistor geometry and fabrication process. Simulations confirm that shape changes of the air-bearing surface induced by microresistor heating are responsible for the actuation. Reproducible flying height variations of 2.3 nm have been confirmed by means of white light interferometry, and actuation efficiencies of 23 nmW**-1 were achieved.

Keywords: Maechtle, Machtle, Haeberle, Haberle