A MEMS piggyback actuator for hard-disk drives

This paper reports a new fabrication process and designing method to integrate MEMS piggyback actuators on a silicon-on-insulator (SOI) wafer with magnetic read/write heads of hard-disk drives. Large bandwidth of the tracking servo system is designed by reducing the load mass for the tracking microactuator to be around 40 μg. A prototype electrostatic MEMS actuator (2 mm × 3 mm × 0.6 mm) of multiple parallel plates has been successfully integrated by using high-aspect ratio microstructures (gap opening 2 μm into 50-μm-SOI wafer) patterned by deep reactive-ion-etching (DRIE). A dc displacement of 0.5 μm, which is almost the same size as data track width, has been obtained at a driving voltage of dc 60 V and the fundamental resonance is found at 16 kHz. An analytical model of the MEMS piggyback actuator has been proposed to predict electromechanical performance. The fabrication method proposed here is very simple and straightforward to put the head-element-drive mechanism into practice.