A Single-Wafer-Processed XY-Stage Fabricated with Trench-sidewall Doping and Refilled-Trench Isolating Technology

For nano-metric positioning and manipulation, a single-crystalline-silicon XY-stage is fabricated by using a double-sided bulk-micromachining technology. For defining different electrostatic actuators in one ordinary wafer (instead of SOI wafer), a trench-sidewall electric isolation method is developed. Previously insulator-refilled trench-bars are used to cut and isolate the different comb-drive actuating elements on the structural trench-sidewalls. Combined with the reverse-biasd isolation of p-n junctions along the boron-diffused trench- sidewall for comb-driving, individual actuators can be operated independently. For maximizing the actuating stroke that is limited by the fabricated minimal comb-gap, a two-segment comb with a gentle-curve transition is designed for both improving actuation-amplitude and avoiding side-instability of the stage. Under 23 V actuating voltage, the moving stroke is about 10 mum in each of the four directions. Compared with conventional comb structure, the new comb design contributes 70% improvement in driving amplitude. Nano pitches on PMMA film are recorded by an electric-heated SPM probe. Coated with PMMA film, the stage movement is precisely controlled, resulting in controllable nano recording.