Micromachined Thermal Multimorph Actuators Fabricated by Bulk-etched MUMPs Process
A. Tuantranont and V.M. Bright
National Electronics and Computer Technology Center (NECTEC), TH
Keywords: MEMS, Thermal actuators, MUMPs
Micromachined thermal multimorph actuators for out-of-plane displacements have been designed and fabricated by Multi-Users MEMS Process (MUMPs) with a post-processing bulk etching step. Micromachined actuators have potential applications in microtransducers such as scanning tunneling microscope (STM) tips, optical scanners, micromirrors and microrobots. By this method, the surface and bulk micromachining can be done and integrated on the same chip. Due to small displacement and small force produced by electrostatic actuators, the alternative way to actuate using thermal actuators is of interest. Our actuator consists of a multilayer micromachined beam constructed of various combinations of polysilicon, oxide and metal layers. Embedded polysilicon wire is used to heat the multimorph to achieve tip deflection. The tip displacement is a function of the actuator design parameters, such as beam material composition, layer thickness and beam length. The maximum tip deflection of 2.5 micron with an input power of 40 mW is achieved. The maximum operating frequency of 2.7 kHz is measured by focus laser reflecting method. A design methodology, device fabrication, and device characterization are presented.
Nanotech 2004 Conference Technical Program Abstract