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Miniature microphones: non-standard fabrication approaches and associated modeling issues

Author(s): L. Rufer

Doc. Source: 175th Meeting: Acoustical Society of America

Publisher: AIP

Pages: 1777

Micro-electro-mechanical systems (MEMS) allowed miniature microphones that during the last few decades have left research laboratories to enter a massive industrial development. Their characteristics meet the most demanding specifications of various portable devices. This talk will show some non-standard approaches to the fabrication technology and associated modeling issues using two cases of specific designs in support. The first case is a piezoresistive microphone devoted to high-intensity and high-frequency acoustic fields. To damp the resonance, an atypical diaphragm structure was employed. Such a solution, allowing relatively large airgap required by large diaphragm displacements, will be presented and analyzed. The second case concerns a design of a microphone fabricated with a standard complementary metal oxide semiconductor (CMOS) technology. This technology, in contrast with dedicated technologies typically used by the microphone industry, is readily available to small companies and academic institutions. One of the drawbacks of the CMOS-MEMS approach is a relatively high degree of design constraints represented by materials and layers dimensions involved in the CMOS process. Moreover, the device layout must take into account specific requirements of the fabrication technique. This talk will present some of these constraints and their impact on the microphone performance that will be supported by simulation results.