Design and fabrication of a novel single-chip MEMS capacitive microphone using slotted diaphragm

A novel single-chip microelectromechanical systems (MEMS) capacitive microphone with a slotted diaphragm for sound sensing is developed to minimize the microphone size and improve the sensitivity by decreasing the mechanical stiffness of the diaphragm. According to the results, a clamped microphone with a 2.43 x 2.43-mm(2) diaphragm and a slotted one with a 1.5- x 1.5-mm(2) diaphragm have the same mechanical sensitivity, but the size of slotted microphone is at least 1.62 times smaller than clamped structure. The results also yield a sensitivity of 5.33 x 10(-6) pF/Pa for the clamped and 3.87 x 10(-5) pF/Pa for the slotted microphone with a 0.5 x 0.5-mm(2) diaphragm. The sensitivity of the slotted diaphragm is increased 7.27 times. The calculated pull-in voltage of the clamped microphone is 214 V, the measured pull-in voltage of the slotted one is 120 V. The pull-in voltage of the slotted microphone is about 50% decreased. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3091941]