Fabrication and characterization of SU-8-based capacitive micromachined ultrasonic transducer for airborne applications

Jose Joseph; Shiv Govind Singh; Siva Rama Krishna Vanjari

doi:10.1117/1.JMM.17.1.015003

14 February 2018 Fabrication and characterization of SU-8-based capacitive micromachined ultrasonic transducer for airborne applications

Jose Joseph, Shiv Govind Singh, Siva Rama Krishna Vanjari

Author Affiliations +

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 17, Issue 1, 015003 (February 2018). https://doi.org/10.1117/1.JMM.17.1.015003

Abstract

We present a successful fabrication and characterization of a capacitive micromachined ultrasonic transducer (CMUT) with SU-8 as the membrane material. The goal of this research is to develop a post-CMOS compatible CMUT that can be monolithically integrated with the CMOS circuitry. The fabrication is based on a simple, three mask process, with all wet etching steps involved so that the device can be realized with minimal laboratory conditions. The maximum temperature involved in the whole process flow was 140°C, and hence, it is post-CMOS compatible. The fabricated device exhibited a resonant frequency of 835 kHz with bandwidth 62 kHz, when characterized in air. The pull-in and snapback characteristics of the device were analyzed. The influence of membrane radius on the center frequency and bandwidth was also experimentally evaluated by fabricating CMUTs with membrane radius varying from 30 to 54 μm with an interval of 4 μm. These devices were vibrating at frequencies from 5.2 to 1.8 MHz with an average Q-factor of 23.41. Acoustic characterization of the fabricated devices was performed in air, demonstrating the applicability of SU-8 CMUTs in airborne applications.

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Jose Joseph, Shiv Govind Singh, and Siva Rama Krishna Vanjari "Fabrication and characterization of SU-8-based capacitive micromachined ultrasonic transducer for airborne applications," Journal of Micro/Nanolithography, MEMS, and MOEMS 17(1), 015003 (14 February 2018). https://doi.org/10.1117/1.JMM.17.1.015003

Received: 2 August 2017; Accepted: 19 January 2018; Published: 14 February 2018

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