Open-circuit sensitivity model based on empirical parameters for a capacitive-type MEMS acoustic sensor. Issue 1 (January 2016)

• Record Type: Journal Article
• Authors: Lee, Jaewoo; Jeon, J.H.; Je, C.H.; Lee, S.Q.; Yang, W.S.; Lee, S.-G.
• Is Part Of: IOP conference series. Volume 108:Issue 1(2016)
• Publication Date: 2016-01
• Subjects: Materials science -- Periodicals; 620.1105
• DOI: 10.1088/1757-899X/108/1/012044
• Languages: English
• ISSNs: 1757-8981

Abstract

Abstract: An empirical-based open-circuit sensitivity model for a capacitive-type MEMS acoustic sensor is presented. To intuitively evaluate the characteristic of the open-circuit sensitivity, the empirical-based model is proposed and analysed by using a lumped spring-mass model and a pad test sample without a parallel plate capacitor for the parasitic capacitance. The model is composed of three different parameter groups: empirical, theoretical, and mixed data. The empirical residual stress from the measured pull-in voltage of 16.7 V and the measured surface topology of the diaphragm were extracted as +13 MPa, resulting in the effective spring constant of 110.9 N/m. The parasitic capacitance for two probing pads including the substrate part was 0.25 pF. Furthermore, to verify the proposed model, the modelled open-circuit sensitivity was compared with the measured value. The MEMS acoustic sensor had an open- circuit sensitivity of -43.0 dBV/Pa at 1 kHz with a bias of 10 V, while the modelled open- circuit sensitivity was -42.9 dBV/Pa, which showed good agreement in the range from 100 Hz to 18 kHz. This validates the empirical-based open-circuit sensitivity model for designing capacitive-type MEMS acoustic sensors.