Acoustic sealing of silicon MEMS microspeakers by the means of polymer films

作者：Houdouin A^*; Shahosseini I; Yaakoubi N; Lefeuvre E; Martincic E; Auregan Y; Durand S

来源：Journal of Optoelectronics and Advanced Materials, 2013, 15(5-6): 463-470.

• MEMS
• Microspeaker
• Acoustic leakage
• FEM
• Polymer
• PDMS
• Seal
• Dry resist film

We present here a silicon MEMS microspeaker with an acoustic leakage reduction polymer sealing. The silicon MEMS microspeakeris formed by a silicon emissive surface suspended by thin silicon suspension beams. The high rigidity of the acoustic emissive surface is obtained thanks to the design of stiffeners located on its backside. Its displacement is obtained by an electrodynamic actuator, i.e. a micromachined planar coil manufactured onto the emissive surface and placed in the near vicinity of a permanent magnet. Out of plane displacements up to +/- 400 pm are possible without failure of the structure and 80 dB(SPL) at 10 cm were obtained. The performances of silicon microspeakers can be further improved by an optimized sealing between the static part and the emissive surface. The sealing requires high mechanical compliance and low mass to limit its impact on the microspeaker's characteristics. A thin polymer (PolyDiMethylSiloxane or dry resist film) seal has been designed with finite elements modelling. We demonstrate that the stiffness added by the seal can be reduced by a factor 10 compared to the same material seal with no forming. A fabrication process with a dedicated homemade vacuum forming set-up is presented.

• 出版日期2013-6