Design and Fabrication of Aluminum Nitride Piezoelectric Micromachined Ultrasonic Transducers for Air Flow Measurements

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Beam-drift based flow measurement technique requires frequency matched ultrasound transmitters and receivers for determining the flow rate. Aluminum nitride (AlN) piezoelectric micromachined ultrasonic transducers (PMUTs) suitable for such an application have been designed and fabricated. The bottom electrode is designed in such way that it reduces the stray capacitances, without degrading the piezoelectric properties of the AlN layer deposited on it. Frequency matching within a PMUT array and PMUTs fabricated across a wafer are challenging due to residual stress and membrane radius variations. A fabrication process to reduce the residual stress by optimizing the AlN layer deposition parameters, and membrane radius variations by optimizing Deep Reactive Ion Etching (DRIE) process, is developed in this work. The relative frequency variation (Δf*100/f) of the fabricated 7-element transmitter array is 0.5 %, and the variation between two receiver elements is 0.8%. Even though there is frequency variation across the wafer, PMUT transmitters and receivers within a reticle have matching frequencies and they can be utilized as transmitter-receiver pairs for flow measurement applications.
Original languageEnglish
Title of host publication2019 IEEE International Ultrasonics Symposium, IUS 2019
PublisherIEEE Institute of Electrical and Electronic Engineers
Pages2489-2492
Number of pages4
ISBN (Electronic)978-1-7281-4596-9, 978-1-7281-4595-2
ISBN (Print)978-1-7281-4597-6
DOIs
Publication statusPublished - 6 Oct 2019
MoE publication typeA4 Article in a conference publication
Event2019 IEEE International Ultrasonics Symposium, IUS 2019 - Glasgow, United Kingdom
Duration: 6 Oct 20199 Oct 2019

Conference

Conference2019 IEEE International Ultrasonics Symposium, IUS 2019
CountryUnited Kingdom
CityGlasgow
Period6/10/199/10/19

Keywords

  • OtaNano

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