In situ tuning of a MEMS microphone using electrodeposited nanostructures

This paper presents a new method for in situ tuning of acoustic sensitivity in micro-electro-mechanical-system (MEMS) microphones using silver metallic nano-electrodeposits. The nano-electrodeposits are electrochemically formed using an external dc bias under low power and at room temperature on an Ag-doped Ge30Se70 solid electrolyte film integrated with the microphone diaphragm. The growth/retraction mechanism generates mass/stress redistribution on the diaphragm and this effect is used to manipulate microphone sensitivity to incoming acoustic waves. Acoustic measurements with a reference microspeaker demonstrate that the microphone can achieve a tuning range of 0.6 dB (7.2%). This technique is useful for a variety of microdevice applications, including sensitivity matching for directional microphones (e.g., in hearing aids), post-package trimming and resonant frequency tuning.

[1]  M. Mehregany,et al.  Characterization of frequency tuning using focused ion beam platinum deposition , 2007 .

[2]  C. Trautmann,et al.  Towards a nanostructured thermoelectric generator using ion-track lithography , 2008 .

[3]  Ramani Duraiswami,et al.  Flexible and Optimal Design of Spherical Microphone Arrays for Beamforming , 2007, IEEE Transactions on Audio, Speech, and Language Processing.

[4]  Brian C J Moore,et al.  Evaluation of the noise reduction system in a commercial digital hearing aid: Evaluación del sistema de reducción de ruido en un auxiliar auditivo digital comercial , 2003, International journal of audiology.

[5]  M. Kozicki,et al.  A Low-Power Nonvolatile Switching Element Based on Copper-Tungsten Oxide Solid Electrolyte , 2006, IEEE Transactions on Nanotechnology.

[6]  M. Mitkova,et al.  In Situ Measurements of X-Ray-Induced Silver Diffusion into a Ge30Se70 Thin Film , 2008 .

[7]  Liwei Lin,et al.  Characterization of selective polysilicon deposition for MEMS resonator tuning , 2003 .

[8]  M. Kozicki,et al.  In situ tuning of omnidirectional microelectromechanical-systems microphones to improve performance fit in hearing aids , 2008 .

[9]  Bernard Widrow,et al.  Microphone arrays for hearing aids: An overview , 2003, Speech Commun..

[10]  Thomas A. Powers,et al.  Three‐microphone instrument is designed to extend benefits of directionality , 2002 .

[11]  Morphology of electrochemically grown silver deposits on silver-saturated Ge-Se thin films , 2003 .

[12]  S. Maruno,et al.  Reversible photowriting and thermal erasing of Ag patterns on Ag-rich Ag-Ge-S films , 1994 .

[13]  James Hone,et al.  Electrothermal frequency tuning of a nano-resonator , 2006 .

[14]  M. Kozicki,et al.  Nanoscale memory elements based on solid-state electrolytes , 2005, IEEE Transactions on Nanotechnology.

[15]  M. Kozicki,et al.  Silver incorporation in Ge-Se glasses used in programmable metallization cell devices , 2002 .

[16]  Fan-Gang Zeng,et al.  Using hearing aid directional microphones and noise reduction algorithms to enhance cochlear implant performance , 2004 .

[17]  M. Kozicki,et al.  Bipolar and Unipolar Resistive Switching in Cu-Doped $ \hbox{SiO}_{2}$ , 2007, IEEE Transactions on Electron Devices.

[18]  M. Kozicki,et al.  Mass transport in chalcogenide electrolyte films - materials and applications , 2006 .

[19]  Mark Sheplak,et al.  Development of a MEMS Dual Backplate Capacitive Microphone for Aeroacoustic Measurements , 2006 .

[20]  Maria Mitkova,et al.  Local structure resulting from photo and thermal diffusion of Ag in Ge-Se thin films , 2004 .