Integrated microheaters for in-situ flying-height control of sliders used in hard-disk drives

Air-bearing sliders in today's hard-disk drives are flying above the spinning magnetic disks at a very low distance. With continuously increasing recording density this distance reduces and will fall below ten nanometers in the near future. This paper discusses the use of thin-film microheaters integrated into the air-bearing surface of such sliders for in-situ flying-height control. The microheaters can be realized with only a few fabrication steps that can be added to the standard slider manufacturing process. The microheaters transfer thermal energy into the sliders leading to nonuniform deformation, of the air-bearing surfaces. As a consequence the balance between the air cushion lift forces and the load forces is shifted and the flying height is varied. A transfer of thermal energy into the air cushion is also discussed. A comparison of experiments and simulations reveals that microheater-induced changes in the waviness of the air-bearing surface are responsible for flying-height actuation with both polarities. Based on this finding actuation schemes with improved efficiency are discussed that offer the possibility of compensating manufacturing tolerances and also of improving the reliability of future hard-disk drives.