Fabrication and characterization of DRIE-micromachined electrostatic microactuators for hard disk drives

In this paper, deep micromachined three-dimensional (3-D) electrostatic microactuators used for dual-stage positioning system of hard disk drives are reported. Actuators with parallel-arranged comb drives enhance the electrostatic driving force. By using proper flexures, secondary stage actuators will drive the magnetic head with fast response and high accuracy. Fabrication of the actuators starts with a 200-μm-thick n-type silicon wafer, and it is subsequently bonded to a Pyrex glass substrate, which can be called silicon-on-glass process. This process is more cost-effective than the SOI wafer process, and the high aspect ratio structures with large thickness also provide good strength and reliability for the microactuators. Deep RIE and wafer bonding techniques were utilized to fabricate the electrostatic actuators. The fabricated actuators were statically and dynamically characterized for three different designs of straight-flexures, folded-flexures and quad-flexures with bandwidth of 7.15, 5.85 and 15.85 kHz, respectively. With proper designed flexures, the proposed microactuators would fulfill the requirements of the dual-stage servo of hard disk drives.