Abstract
This paper explained the dependency of collapse voltage on semiconductor device structural features (membrane diameter, membrane thickness and the vertical distance between the electrodes) and physical characteristics (mechanical residual stress of the silicon nitride membrane) considering the electro-mechanical model of MEMS based Capacitive micromachined ultrasonic transducer (CMUT). To have sensitivity comparable to that of piezoelectric ultrasonic transducers (UTs), CMUTs need to be biased close to the collapse voltage. Maximum efficiency is achieved in the conventional mode of operation by biasing the device close to the collapse voltage. The total acoustic output pressure is determined by the efficiency of the device. Hence a careful investigation of the same is decidedly required. Finite element method (FEM) model by PZFlex and analytical model of single element CMUT with 0.75 µm thick silicon nitride membranes suspended on 0.5 µm thick cavity were developed showing resonance frequency at 5 MHz. Through these analyses, it is observed that membrane and vacuum gap thickness are both directly proportional to collapse voltage, while radius of the membrane and also its area are inversely proportional to collapse voltage. Initially the spring softening effect of the membrane has been neglected. Later the effect has been included in the proposed model and analyzed. It has been shown that the spring softening effect cannot be neglected for accurate CMUT modeling. A capacitive micromachined ultrasound transducer can be realized with the model described in this paper.
Similar content being viewed by others
References
Arezoo T, Buchanan DA (2015) Design and characterization of a capacitive micromachined transducer with a deflectable bottom electrode. IEEE Electron Device Lett 36(6):612–614
Aydogdu E, Ozgurluk A, Atalar A, Koymen H (2014) Parametric nonlinear lumped element model for circular CMUTs in collapse mode. IEEE Trans Ultrason Ferroelectr Freq Control 61(8):1245–1260
Bozkurt A, Yaralioglu GG (2016) Receive noise analysis of capacitive micromachined ultrasonic transducers. IEEE Trans Ultrason Ferroelectr Freq 63(11):1980–1987
Caronti A, Caliano C, Carotenuto R, Savoia A, Papalardo M, Cianci E, Foglietti V (2006) Analysis of acoustic interaction effect sand crosstalk in CMUT linear arrays for medical imaging. Microelectron J 37:770–777
Chen A, Wong L, Na S, Li Z, Mcecek M, Yeow J (2016) Fabrication of a curved row-column addressed capacitive micromachined ultrasonic transducer array. IEEE J Microelectromech Syst 25(4):675–682
Cheng TC, Hsu CW, Wang HC, Parvizand B, Tsai TH (2016) A low-power oscillator-based readout interface for medical ultrasonic sensors. In: 2016 International symposium on VLSI design, automation and test (VLSI-DAT). IEEE, Taiwan
Cour MF, Christiansen TL, Jensen JA, Thomsen EV (2015) Electrostatic and small signal analysis of CMUTs with circular and square anisotropic plates. IEEE Trans Ultrason Ferroelectr Freq Control 62(8):1563–1579
Emadi TA, Buchanan DA (2013) Multiple moving membrane CMUT with enlarged membrane displacement and low pull-down voltage. IEEE Electron Device Lett 34(12):1578–1580
Emadi TA, Buchanan DA (2014) Design and fabrication of a novel MEMS capacitive transducer with multiple moving membrane, M3-CMUT. IEEE Trans Electron Devices 61(3):890–896
Emadi TA, Buchanan DA (2015) Design and characterization of a Capacitive micromachined transducer with a deflectable bottom electrode. IEEE Electron Device Lett 36(6):612–614
Haller MI, Khuri-Yakub BT (1994) A surface micromachined electrostatic ultrasonic air transducer. In: IEEE Ultrasonics symposium, pp 1241–1244
Haller MI, Khuri-Yakub BT (1996) A surface micromachined electrostatic ultrasonic air transducer. IEEE Trans Ultrason Ferroelectr Freq Control 43(1):1–6
Ladabaum I, Chin X, Soh HT, Atalar A, Khuri-Yakub BT (1998) Surface micromachined capacitive ultrasonic transducers. IEEE Trans Ultrason Ferroelectr Freq Control 45(3):678–690
Lee SM (2011) Viscous damping effect on the CMUT device in air. J Korean Phys Soc 58(4):747–755
Maity R, Maity NP, Baishya S (2017a) Circular membrane approximation model with the effect of the finiteness of the electrode’s diameter of MEMS capacitive micromachined ultrasonic transducers. Microsyst Technol 23(8):3513–3524
Maity R, Maity NP, Baishya S (2017b) An improved analytical and finite element method model of nanoelectromechanical system based micromachined ultrasonic transducers. Microsyst Technol 23(6):2163–2173
Maity R, Maity NP, Guha K, Baishya S (2018) Analysis of fringing capacitance effect on the performance of micro-electromechanical-system-based micromachined ultrasonic air transducer. Micro Nano Lett 13(6):872–877
N’Djin W, Gerold B, Bailly J, Canney M, Nguyen-Dinh A, Carpentier A, Chapelon J (2017) Capacitive micromachined ultrasound transducers for interstitial high-intensity ultrasound therapies. IEEE Trans Ultrason Ferroelectr Freq Control 64(8):1245–1260
Nikoozadeh A, Bayram B, Yaralioglu GG, Khuri-Yakub BT (2004) Analytical calculation of collapse voltage of CMUT membrane. In: IEEE Ultrasonics symposium, pp 256–259
Ronnekleiv A (2005) CMUT array modeling through free acoustic CMUT modes and analysis of the fluid CMUT interface through Fourier transform methods. IEEE Trans Ultrason Ferroelectr Freq Control 52(12):2173–2184
Roy R, Farhanieh O, Ergun A, Bozkurt A (2017) Fabrication of High-Efficiency CMUTs With Reduced Parasitic Using Embedded Metallic Layers. IEEE Sens J 17(13):4013–4020
Soh HT, Ladabaum I, Atalar A, Quate CF, Khuri-Yakub BT (1996) Silicon micromachined ultrasonic immersion transducers. Appl Phys Lett 69(24):3674–3676
Timoshenko S, Woinowsky-Krieger S (1959) Theory of plates and shells, 2nd edn. McGraw-Hill College, New York
Zhang Q, Cicek PV, Allidina K, Nabki F, El-Gamal MN (2014) Surface micromachined CMUT using low temperature deposited silicon carbide membranes for above IC integration. IEEE J Microelectromech Syst 23(2):482–492
Zhang X, Yamancer FY, Oralkan O (2017) Fabrication of vacuum-sealed-capacitive micromachined ultrasonic transducers with through glass via interconnects using anodic bonding. IEEE J Microelectromech Syst 26(1):226–234
Acknowledgements
The authors are highly indebted to University Grant Commission (UGC), Ministry of Human Research Development (MHRD), Govt. of India for supporting this technical work.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Maity, R., Maity, N.P., Guha, K. et al. Analysis of spring softening effect on the collapse voltage of capacitive MEMS ultrasonic transducers. Microsyst Technol 27, 515–523 (2021). https://doi.org/10.1007/s00542-018-4040-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00542-018-4040-x