In situ tuning of a MEMS microphone using electrodeposited nanostructures

• Published in: Journal of micromechanics and microengineering Vol. 19; no. 3; pp. 035015 - 035015 (8)
• Main Authors: Je, Sang-Soo, Harrison, Jere C, Kozicki, Michael N, Bakkaloglu, Bertan, Kiaei, Sayfe, Chae, Junseok
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2009; Institute of Physics
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Acoustic measurement; Doping; Nanostructures; Low power; Microphones; Silver; Ambient temperature; Resonance frequency; Hearing aids; Electrodeposition; Diaphragm; Microelectromechanical device; Acoustic waves
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/19/3/035015

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 Ge 30 Se 70 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.