Buckling control of silicon dioxide diaphragms by lateral stress enhancement for sensitivity improvement of piezoelectric ultrasonic microsensors

Yamashita, K.; Watanabe, Tetsuya; Yoshizaki, Tomoya; Noda, Minoru; Okuyama, Masanori

doi:10.1016/j.sna.2010.04.007

Cited by 11 publications

(5 citation statements)

References 13 publications

(19 reference statements)

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“…In order to improve the properties of pMUT, Belgacem studied the influence of centred and ring top electrode on the coupling factor of pMUT with a circular piezoelectric composite diaphragm released by the expensive deep reactive ion etch (DRIE) process, and they found that when the PZT was removed outside the electrode this can improve the coupling factor [ 28 ]. The vibration diaphragms of pMUTs include piezoelectric films and non-piezoelectric layers, and if released by wet etching they are square for anisotropic etching of silicon [ 29 , 30 , 31 ]. The wet etching process is simpler and cheaper than DRIE that can realize circular piezoelectric composite diaphragm.…”

Section: Introductionmentioning

confidence: 99%

Design and Fabrication of Piezoelectric Micromachined Ultrasound Transducer (pMUT) with Partially-Etched ZnO Film

Ren

Fan

et al. 2017

Sensors

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A square piezoelectric composite diaphragm was analyzed by the finite element method to enhance the sensitivity of a piezoelectric micromachined ultrasound transducer (pMUT). The structures of electrode and piezoelectric film were optimized and a centric electrode was designed to avoid the counteraction of stress in the centre and edges. In order to further improve the sensitivity; a pMUT with partially-etched piezoelectric film was adopted. The receive and transmit sensitivities of the pMUT were analyzed in details. The receive sensitivity of pMUT with partially-etched ZnO film is 3.3 dB or 6.8 dB higher than those with a centric and whole electrode, respectively; and the amplitude of a partially-etched ZnO film pMUT under a certain voltage is 5.5 dB and 30 dB higher than those with centric and whole electrode separately. Two pMUT-based ZnO films were fabricated by micromachining technology and their receive and transmit sensitivities were tested. The ZnO films deposited by direct current (DC) magnetron sputtering exhibit a densely packed structure with columnar crystallites. The test results show that the structure of the square diaphragm with partially-etched piezoelectric layer can significantly improve the transducer sensitivity. The receive sensitivity and transmit sensitivity are −238.35 dB (ref. 1 V/μPa) and 150.42 dB (ref. 1 μPa/V); respectively.

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Section: Introductionmentioning

confidence: 99%

Design and Fabrication of Piezoelectric Micromachined Ultrasound Transducer (pMUT) with Partially-Etched ZnO Film

Ren

Fan

et al. 2017

Sensors

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“…However, when the membrane is deflected upward, the total stress is the sum of both the absolute expansion and bending stresses, and the sensitivity is much larger than that of the downward-deflected membrane. In order to enhance the sensitivity, the membranes were deflected upward by various methods such as pulling the membrane through a cover by a vacuum aspiration technique, reducing the thickness of PZT film and removing PZT thin film other than the center electrode [20]. Figure 5 shows transient responses of the sensors, of which the membranes are deflected upward and downward.…”

Section: Enhancement Of Sensitivitymentioning

confidence: 99%

Miniature Ultrasonic and Tactile Sensors for Dexterous Robot

Okuyama¹,

Yamashita²,

Noda³

et al. 2012

Transactions on Electrical and Electronic Materials

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Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/SiO 2 and/or Si diaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or Si:B + piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.

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“…There is thus a trade-off relationship between bandwidth and sensitivity, and many studies have aimed at realizing compatibility between the two. [5][6][7][8] The present study examines the effects of various parameters in an effort to achieve both a wide bandwidth and high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Effects of flexural vibration and thickness vibration on receiving characteristics of a diaphragm-type PZT resonator

Suzuki

Tagawa

Yoshizawa

et al. 2020

Jpn. J. Appl. Phys.

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The piezoelectric micromachined ultrasonic transducer (PMUT) is increasingly being used in medical applications with the development of microelectromechanical system technology. The PMUT generates flexural vibration depending on its structure, but there is also thickness vibration depending on the film thickness of the resonator. This paper clarifies the effect of each vibration on the PMUT reception characteristics. Two approaches that may weaken flexural vibration are investigated in finite element simulation. One is thickening the support layer to increase the damping function. The other is increasing the thickness vibration by thickening the lead zirconate titanate (PZT) layer. Results reveal that flexural vibration is strongly related to ringing in the received waveform, owing to flexural vibration generating rapid phase changes in the frequency domain. Meanwhile, thickness vibration, the degree of which depends on the thickness of the PZT layer, is confirmed to affect the pulse width but be less relevant to ringing.

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Buckling control of silicon dioxide diaphragms by lateral stress enhancement for sensitivity improvement of piezoelectric ultrasonic microsensors

Cited by 11 publications

References 13 publications

Design and Fabrication of Piezoelectric Micromachined Ultrasound Transducer (pMUT) with Partially-Etched ZnO Film

Design and Fabrication of Piezoelectric Micromachined Ultrasound Transducer (pMUT) with Partially-Etched ZnO Film

Miniature Ultrasonic and Tactile Sensors for Dexterous Robot

Effects of flexural vibration and thickness vibration on receiving characteristics of a diaphragm-type PZT resonator

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