Fabrication of High-Efficiency CMUTs With Reduced Parasitics Using Embedded Metallic Layers

Roy, Rupak Bardhan; Farhanieh, Omid; Ergun, A.S.; Bozkurt, Ayhan

doi:10.1109/jsen.2017.2704623

Cited by 6 publications

(2 citation statements)

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“…Another approach to reduce the CMUT parasitic capacitance is using embedded patterned BE layers to minimize the overlap between top and bottom electrodes [13,14]. Using embedded electrode method to make topography-free surfaces adds an extra etching step, significantly increasing the roughness of the dielectric surface due to etching.…”

Section: Introductionmentioning

confidence: 99%

“…Cavity edge insulator extension method has been recently proposed in [15] to increase the reliability in CMUT cells for high ultrasound power transmission application. Although it significantly increases the breakdown voltage and CMUT's lifetime, using the sandwich method like [14], increases the effective gap resulting in degrading device performance. Besides, this approach adds an extra etching step and also height difference over the edges of the membranes-since the new PE-SiO 2 layer exclusively stays on the edge of the membranes-that makes the following deposition/patterning processes difficult.…”

Section: Introductionmentioning

confidence: 99%

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Low temperature CMUT fabrication process with dielectric lift-off membrane support for improved reliability

Pirouz

Degertekin

2018

J. Micromech. Microeng.

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This paper reports an improved CMOS compatible low temperature sacrificial layer fabrication process for Capacitive Micromachined Ultrasonic Transducers (CMUTs). The process adds the fabrication step of silicon oxide evaporation which is followed by a lift-off step to define the membrane support area without a need for an extra mask. This simple addition improves reliability by reducing the electric field between the top and bottom electrodes everywhere except the moving membrane without affecting the vacuum gap thickness. Furthermore, the parasitic capacitance which degrades the CMUT receive performance is reduced. A 1-D CMUT array suitable for Intracardiac Echocardiography (ICE) imaging with 9MHz center frequency is fabricated using this method. Detailed electrical and acoustic testing indicates adequate performance of the devices for ICE in agreement with simulations. Long term output pressure testing with more than 2×10 pulsing cycles and environmental testing demonstrate the efficacy of the approach for improved reliability as compared to devices without the additional membrane support layer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%