Fabrication process of polymeric springs for MEMS applications

This paper presents a novel wafer-level fabrication technique and the characterization method for polymeric springs combined with silicon proof mass for MEMS force sensors or micromirrors. The large difference of material stiffness between spring material and proof mass material combined with the much smaller thickness of the springs gives the possibility to concentrate the entire mechanical deformation into the springs. Furthermore, the polymeric springs can be used as electrically isolated suspension for electrostatic levitation devices. Test structures have been fabricated and characterized by means of frequency response analysis. Therefore, we present a polymeric suspension with a spring constant of 8.7 N/m, while the suspended structure itself features a spring constant of 140 kN/m.