![[PukiWiki]](image/XYstage.jpg "[PukiWiki]")
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We have developed a novel device architecture for comb-driven double-gimbal XY-stage of high fill-factor (stage area / chip size), which has been realized for the first time by topologically separating the actuator elements into two layers: all the electrical parts (electrodes and inter-connections) are in the Silicon-on-Insulator (SOI) layer, while the mechanical parts (suspensions, frames, and XY-stage) are in the substrate. Thanks to the newly developed layered structures, the footprint of the actuator has been made small.
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The stage size of 1 mm by 1mm in area with respect to the chip size of 2 mm x 2 mm gave a fill factor of 25%. The tiny folded-tether made of the SOI silicon (seen in the middle of Figure(b)) was used to electrically connect the movable electrode on the stage to the GND level. It was designed to have a negligible spring constant such that that the stage motion would not be interfered. All the substrate parts were pulled down to the electrical GND. The center stage on the SOI layer was also electrically grounded by using a thin cantilever of silicon (1000 um long and 15 um wide, Figure (c)) that had been bonded to the substrate surface by the process stiction.
