Design considerations in micromachined silicon microphones

Miao, Jianmin; Lin, Rongping; Chen, Lei; Zou, Quanbo; Lim, Sin Yee; Seah, Suan Hee

doi:10.1016/s0026-2692(01)00100-8

Cited by 53 publications

(17 citation statements)

References 9 publications

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“…A possibility for addressing the stress issue is to reduce the fabrication-induced stress by optimizing the deposition processes. Another effective method to alleviate residual stress in diaphragm and to optimize its mechanical sensitivity is the utilization of corrugation technique [36]- [39]. The application of corrugation offers the possibility to control mechanical sensitivity by means of dimensions of corrugations and the number of corrugations to be used, which is often an easier way compared to the approach by process control.…”

Section: B Stress-tolerant Design By Corrugations In the Diaphragmmentioning

confidence: 99%

A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm

Miao

Oberhammer

2008

J. Microelectromech. Syst.

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This paper presents a ruthenium metal-contact RF microelectromechanical system switch based on a corrugated silicon oxide/silicon nitride diaphragm. The corrugations are designed to substantially reduce the influence of the fabricationinduced stress in the membrane, resulting in a highly insensitive design to process parameter variations. Furthermore, a novel multilayer metal-contact concept, comprising a 50-nm chromium/ 50-nm ruthenium/500-nm gold/50-nm ruthenium structure, is introduced to improve the contact reliability by having a hard-metal surface of ruthenium without substantial compromise in the contact and transmission-line resistances, which is shown by theoretical analysis of the contact physics and confirmed by measurement results. The contact resistance of the novel metallization stack is investigated for different contact pressures and is compared to pure-gold contacts. The contact reliability is investigated for different dc signal currents. At a measurement current of 1.6 mA, the Ru-Au-Ru contacts have an average lifetime of about 100 million cycles, whereas the Au-Au contacts reach 24 million cycles only. For larger signal currents, the metal contacts have proven to be more robust over the Au-Au contacts by a factor of ten. The measured pull-in voltage is reduced significantly from 61 V for flat diaphragm to 36 V for corrugated diaphragm with the introduction of corrugation. The measured RF isolation with a nominal contact separation of 5 µm is better than −30 dB up to 4 GHz and still −21 dB at 15 GHz, whereas the insertion loss of the fully packaged switch including its transmission line is about −0.7 dB up to 4 GHz and −2.8 dB at 15 GHz.[ 2007-0271]Index Terms-Contact metal, contact resistance, corrugated membrane, RF microelectromechanical system (MEMS) switch, wafer-level packaging.

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Section: B Stress-tolerant Design By Corrugations In the Diaphragmmentioning

confidence: 99%

A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm

Miao

Oberhammer

2008

J. Microelectromech. Syst.

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“…The corrugation technique was also introduced to the diaphragm to alleviate the possible high residual stress in the diaphragm [4]. To demonstrate the switching speed increase by the perforation in the base substrate, the switches were made purposely with a large diaphragm of 1750 ptm in radius and an air gap of 8 pm.…”

Section: Design the Switch Configurationmentioning

confidence: 99%

Performance Enhancement by Substrate Perforation for a Wafer-Level Encapsulated RF MEMS DC Shunt Switch

Miao

Tan

2009

2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems

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A wafer-level encapsulated RF MEMS shunt switch with perforated base substrate and corrugated diaphragm was developed. For the first time, the perforated base substrate by meticulous design is introduced to tremendously reduce squeeze-film damping and thus significantly increase the switching speed.The characterization of the fabricated and wafer-level encapsulated switch in terms of the switching time and RF performance is presented in this paper as well.

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“…Micromachining technology has been used to design and fabricate various silicon microphones. Among them, the capacitive microphone is in the majority because of its high achievable sensitivity, miniature size, batch fabrication, integration feasibility, and long stability performance (Jing et al 2003;Miao et al 2002;Li et al 2001). A capacitive microphone consists of a variable gap capacitor.…”

Section: Introductionmentioning

confidence: 99%

Slotted capacitive microphone with sputtered aluminum diaphragm and photoresist sacrificial layer

Ganji

Majlis

2010

Microsyst Technol

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In this paper, we have fabricated a new microphone using aluminum (Al) slotted perforated diaphragm and back plate electrode, and photoresist (AZ1500) sacrificial layer on silicon wafer. The novelty of this method relies on aluminum diaphragm includes some slots to reduce the effect of residual stress and stiffness of diaphragm for increasing the microphone sensitivity. The acoustic holes are made on diaphragm to reduce the air damping, and avoid the disadvantages of non standard silicon processing for making back chamber and holes in back plate, which are more complex and expensive. Photoresist sacrificial layer is easy to deposition by spin coater and also easy to release by acetone. Moreover, acetone has a high selectivity to resist compared to silicon oxide and Al, thus it completely removes sacrificial resist without incurring significant damage silicon oxide and Al. The measured zero bias capacitance is 17.5 pF, and its pull-in voltage is 25 V. The microphone has been tested with external amplifier and speaker, the external amplifier was able to detect the sound waves from microphone on speaker and oscilloscope. The maximum amplitude of output speech signal of amplifier is 45 mV, and the maximum output of MEMS microphone is 1.125 lV.

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Design considerations in micromachined silicon microphones

Cited by 53 publications

References 9 publications

A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm

A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm

Performance Enhancement by Substrate Perforation for a Wafer-Level Encapsulated RF MEMS DC Shunt Switch

Slotted capacitive microphone with sputtered aluminum diaphragm and photoresist sacrificial layer

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