Design, fabrication and characterization of a single-layer out-of-plane electrothermal actuator for a MEMS XYZ stage

摘要

This paper presents the design, fabrication and characterization of a single-layer out-of-plane electrothermal actuator based on MEMS (Micro-Electro-Mechanical System). The proposed electrothermal actuator is designed to generate motions along the out-of-plane or normal to a wafer by a Joule heating when the current flows through the actuator. This out-of-plane electrothermal actuator is based on a single layer of a SOI (Silicon on Insulator) wafer and two notches near the middle of the actuator beams. Due to these notches, the thermal expansion of the beams in the actuator generates an eccentric loading, which converts into the bending of the beams. This bending of the beam finally generates the out-of-plane motion at the middle of the beam. This behavior is described by the prepared analytic equations and compared by the results from FEM (Finite element Model) analysis. With fabricated samples, a 30 μm displacement is measured along out-of-plane at 5 V driving voltage. The 1st mode of the resonant frequency for the out-of-plane motion is expected to occur at 74.9 kHz from FEA. The proposed actuator is based on the standard SOI-MUMPs (SOI-Multi User Manufacturing Process), so it has good integration capability with other system employing same fabrication techniques. To test its integration capability, a MEMS XYZ stage is fabricated by embedding the proposed out-of-plane electrothermal actuator onto an existing MEMS XY stage. The range of motion of the fabricated XYZ stage is measured about 35 μm × 35 μm × 30 μm along X, Y and Z axes without any changes on its fabrication process.