열풍동형 폴리실리콘 마이크로 액츄에이터의 제작 및 특성 분석

Fabrication of thermally driven polysilicon micro actuator and its characterization

A thermal micro actualtor has been fabricated using surface micromachining techniques. It consists of doped ploysilicon as a moving part and TEOS(Tetra Ethyl Ortho Silicate) as a sacrificial layer. The polysilicon was annealed for the reduction of residual stress which is the main cause to its deformation such as bending and buckling. And the newly developed HF VPE(vapor phase etching)process was also used as an effective release method for the elimination of sacrificaial layer. With noliquid involved during any of the steps for relasing, unlike other reported relase techniques, the HF VPE pocess has produced polysilicon microstructures with virtually no process-induced stiction problem. The actuation is incured by the thermal expasion due to current flow in active polysilicon cantilever, which motion is amplified bylever mechanism. The thickness of pllysilicon is 2 .mu. m and the length of active and passive polysilicon cantilever are 500 .mu. m, respectively. The moving distance of polysilicon actuator was experimentally conformed as large as 21 .mu. m at the input voltage level of 10 V and 50Hz square wave. These micro actuator technology can be utilized for the fabrication of MEMS (microlectromechanical system) such as microrelay, which requires large displacement or contact force but relatively slow response.