Research/Electrostatic Microactuators for HDD Piggyback System

MEMS for Hard-Disk Drive Head Positioning Mechanism†

Recording density of hard-disk drive (HDD) is increasing by more than 60% per year recently, and it has reached over 30 Gbit/in2 for commercial product and 100 Gbit/in2 for R&D level. As the data length is reaching the limit of material property (thermal stabilty), data width is left as the only parameter for us to increase recording density by using a microactuator for fine positioning the read/write head located at the tip of the suspension.

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Piggyback Actuator†

We have used an electrostatic microactuator by DRIE bulk micromachining on an SOI wafer. The picture on the right shows a schematic model using multiple parallel plates for lateral positioning the head (center). The active layer of the SOI wafer is used to form the actuator as well as the movable head element. The bottom part (which used to be the side wall of the substrate) has been polished and patterned into the AB (air bearing) of flying head.

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SOI-MEMS Development†

In our prototype model, we have obtained +/- 0.5 micron displacement at a dc 50 V, which is close to our target (0.5 micron at 30V) for 100 Gbit/in 2 device). The project is hot now for our next target, 200 Gbit/in 2 device.

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