Design, modeling, and fabrication of crab-shape capacitive microphone using silicon-on-isolator wafer

Ganji, Bahram Azizollah; Sedaghat, Sedighe Babaei; Roncaglia, Alessandro; Belsito, Luca; Ansari, R.

doi:10.1117/1.jmm.17.1.015002

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…After the commercialization of the first microelectromechanical system (MEMS) microphone by Knowles in 2002 [1], the microphone market has witnessed a giant leap toward high-performance audio applications meant for consumer electronics, automotive, hearing aids, military, and aerospace markets. The capacitive MEMS microphone industry has attracted significant interest because these designs facilitate small size, reduced cost, low power consumption, high sensitivity, low noise, flat frequency response, and good stability with respect to temperature and humidity [2,3]. The silicon micromachining technology enables high-volume production of MEMS microphone devices with an outstanding level of miniaturization that can be achieved within an area less than 1 mm 2 [4].…”

Section: Introductionmentioning

confidence: 99%

A Novel MEMS Capacitive Microphone with Semiconstrained Diaphragm Supported with Center and Peripheral Backplate Protrusions

et al. 2021

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Audio applications such as mobile phones, hearing aids, true wireless stereo earphones, and Internet of Things devices demand small size, high performance, and reduced cost. Microelectromechanical system (MEMS) capacitive microphones fulfill these requirements with improved reliability and specifications related to sensitivity, signal-to-noise ratio (SNR), distortion, and dynamic range when compared to their electret condenser microphone counterparts. We present the design and modeling of a semiconstrained polysilicon diaphragm with flexible springs that are simply supported under bias voltage with a center and eight peripheral protrusions extending from the backplate. The flexible springs attached to the diaphragm reduce the residual film stress effect more effectively compared to constrained diaphragms. The center and peripheral protrusions from the backplate further increase the effective area, linearity, and sensitivity of the diaphragm when the diaphragm engages with these protrusions under an applied bias voltage. Finite element modeling approaches have been implemented to estimate deflection, compliance, and resonance. We report an 85% increase in the effective area of the diaphragm in this configuration with respect to a constrained diaphragm and a 48% increase with respect to a simply supported diaphragm without the center protrusion. Under the applied bias, the effective area further increases by an additional 15% as compared to the unbiased diaphragm effective area. A lumped element model has been also developed to predict the mechanical and electrical behavior of the microphone. With an applied bias, the microphone has a sensitivity of −38 dB (ref. 1 V/Pa at 1 kHz) and an SNR of 67 dBA measured in a 3.25 mm ´ 1.9 mm ´ 0.9 mm package including an analog ASIC.

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Section: Introductionmentioning

confidence: 99%

A Novel MEMS Capacitive Microphone with Semiconstrained Diaphragm Supported with Center and Peripheral Backplate Protrusions

et al. 2021

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“…Most commercial MEMS acoustic sensors in IoT applications are capacitive-type devices due to their compatibility with the standard complementary metal–oxide–semiconductor (CMOS) process in terms of form factor, thermal stability, and linear frequency response. The capacitive-type MEMS acoustic sensor [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] is composed of two plates, namely, a rigid back plate fixed on a substrate and a flexible diaphragm that detects an input acoustic signal. The moving plate should respond flexibly to the input sound pressure, and the hard bottom plate must have etch holes to reduce the damping effect.…”

Section: Introductionmentioning

confidence: 99%

“…The moving plate should respond flexibly to the input sound pressure, and the hard bottom plate must have etch holes to reduce the damping effect. The characteristics of capacitive-type acoustic sensors are usually evaluated in terms of open-circuit sensitivity [1,3,9,11,14,15], which is determined by lumped parameters: the plate area of the capacitor, the spring constant of the flexible plate, the spacing of the two plates, and the ratio of the parasitic and intrinsic capacitance components. Although the open-circuit sensitivity at the static state can be roughly evaluated by pull-in voltage [1,4,9,11,15] from the capacitance change according to the applied voltage, it is difficult to obtain the parasitic capacitance considering the fringe field effect [17,18] due to the etching hole of the fixed electrode.…”

Section: Introductionmentioning

confidence: 99%

Wafer-Level-Based Open-Circuit Sensitivity Model from Theoretical ALEM and Empirical OSCM Parameters for a Capacitive MEMS Acoustic Sensor

Lee

Kim

et al. 2019

Sensors

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We present a simple, accurate open-circuit sensitivity model based on both analytically calculated lumped and empirically extracted lumped-parameters that enables a capacitive acoustic sensor to be efficiently characterized in the frequency domain at the wafer level. Our mixed model is mainly composed of two key strategies: the approximately linearized electric-field method (ALEM) and the open- and short-calibration method (OSCM). Analytical ALEM can separate the intrinsic capacitance from the capacitance of the acoustic sensor itself, while empirical OSCM, on the basis of one additional test sample excluding the membrane, can extract the capacitance value of the active part from the entire sensor chip. FEM simulation verified the validity of the model within an error range of 2% in the unit cell. Dynamic open-circuit sensitivity is modelled from lumped parameters based on the equivalent electrical circuit, leading to a modelled resonance frequency under a bias condition. Thus, eliminating a complex read-out integrated circuit (ROIC) integration process, this mixed model not only simplifies the characterization process, but also improves the accuracy of the sensitivity because it considers the fringing field effect between the diaphragm and each etching hole in the back plate.

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“…Microelectromechanical systems (MEMS) technology have allowed the development of microphones with characteristics such as a small size, low power consumption, reduced cost, high signal quality and good stability respect to variations of temperature and humidity [ 1 , 2 ]. These microphones can provide a substitute for conventional electret condenser microphones (ECM) in mobile electronics devices, including smartphones, laptops and tablets [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Design and Modeling of a MEMS Dual-Backplate Capacitive Microphone with Spring-Supported Diaphragm for Mobile Device Applications

Peña-García

Aguilera-Cortés

González-Palacios

et al. 2018

Sensors

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New mobile devices need microphones with a small size, low noise level, reduced cost and high stability respect to variations of temperature and humidity. These characteristics can be obtained using Microelectromechanical Systems (MEMS) microphones, which are substituting for conventional electret condenser microphones (ECM). We present the design and modeling of a capacitive dual-backplate MEMS microphone with a novel circular diaphragm (600 µm diameter and 2.25 µm thickness) supported by fifteen polysilicon springs (2.25 µm thickness). These springs increase the effective area (86.85% of the total area), the linearity and sensitivity of the diaphragm. This design is based on the SUMMiT V fabrication process from Sandia National Laboratories. A lumped element model is obtained to predict the electrical and mechanical behavior of the microphone as a function of the diaphragm dimensions. In addition, models of the finite element method (FEM) are implemented to estimate the resonance frequencies, deflections, and stresses of the diaphragm. The results of the analytical models agree well with those of the FEM models. Applying a bias voltage of 3 V, the designed microphone has a bandwidth from 31 Hz to 27 kHz with 3 dB sensitivity variation, a sensitivity of 34.4 mV/Pa, a pull-in voltage of 6.17 V and a signal to noise ratio of 62 dBA. The results of the proposed microphone performance are suitable for mobile device applications.

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Design, modeling, and fabrication of crab-shape capacitive microphone using silicon-on-isolator wafer

Cited by 4 publications

References 16 publications

A Novel MEMS Capacitive Microphone with Semiconstrained Diaphragm Supported with Center and Peripheral Backplate Protrusions

A Novel MEMS Capacitive Microphone with Semiconstrained Diaphragm Supported with Center and Peripheral Backplate Protrusions

Wafer-Level-Based Open-Circuit Sensitivity Model from Theoretical ALEM and Empirical OSCM Parameters for a Capacitive MEMS Acoustic Sensor

Design and Modeling of a MEMS Dual-Backplate Capacitive Microphone with Spring-Supported Diaphragm for Mobile Device Applications

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