Title :
A surface micromachined MEMS capacitive microphone with back-plate supporting pillars
Author :
Chang Han Je ; Jaewoo Lee ; Woo Seok Yang ; Jong-kee Kwon
Author_Institution :
Nano Scale Electron. & Opt. Integration Res. Dept., Electron. & Telecommun. Res. Inst. (ETRI), Daejeon, South Korea
Abstract :
We present a new surface micromachined MEMS capacitive microphone with improved frequency response and high sensitivity. The proposed MEMS microphone has a top back-plate with a bottom sensing membrane and the back-plate is supported by supporting pillars which are anchored to the bottom of the deep back chamber. The back-plate supporting pillars increase the stiffness of the back-plate and prevent deformation. A present surface micromachined MEMS capacitive microphone is fabricated using fully CMOS compatible processes. It has a thin metal membrane of 500 μm diameter, a sensing air gap of 2.5 μm and seven back-plate supporting pillars. A 100 μm deep back chamber is formed by xenon difluoride dry etching of silicon substrate. As a result, the proposed microphone shows a flat frequency response and high open-circuit sensitivity. It shows a measured zero-bias capacitance of 1.0 pF and a pull-in voltage of 11.0 V, and an open-circuit sensitivity of 10.37 mV/Pa on a DC bias of 6.0 V.
Keywords :
CMOS integrated circuits; etching; frequency response; micromachining; micromechanical devices; microphones; CMOS compatible process; MEMS capacitive microphone; back-plate supporting pillars; bottom sensing membrane; capacitance 1.0 pF; deep back chamber; dry etching; frequency response; open-circuit sensitivity; sensing air gap; silicon substrate; size 500 mum; surface micromachine; thin metal membrane; top back-plate; voltage 11.0 V; voltage 6.0 V; xenon difluoride; Capacitance; Micromechanical devices; Microphones; Resonant frequency; Sensitivity; Sensors; Voltage measurement;
Conference_Titel :
SENSORS, 2013 IEEE
Conference_Location :
Baltimore, MD
DOI :
10.1109/ICSENS.2013.6688399
