A two directional electrostatic comb-drive X– Y micro-stage for MOEMS applications

We report the design, fabrication and characterization of a newly developed electrostatic silicon X– Y micro-stage with large displacement, suitable for many MOEMS including raster scanning devices. The micro-stage consists of four electrostatic comb-drive actuators driving a suspended movable platform via a system of straight spring suspensions and converting their deflections into a linear motion. Independent driving of the platform along X- and Y-direction has been achieved by employing a “stage-in-the-stage” construction of the movable structure, mechanically linked by suspended insulation bridges. Experimental characteristics have shown the large static translations of ±28 μm along X-axis and ±37 μm along Y-axis, at a driving voltage of 100 V. The resonant frequency at the fundamental mode in the X-direction (290 Hz) was lower than in the Y-direction (550 Hz) while the maximum out-of-plane displacement was measured to be 26 nm within the bandwidth of 0–5 kHz. The device was fabricated by double-side DRIE of a silicon-on-insulator (SOI) wafer with 30-μm-thick device layer. The micro-stage is intended to be integrated with micro-optical components (microlens, diffraction grating) and offers an attractive solution to build miniature and low cost 2D raster scanning modules.