Fabrication and characterization of surface CMUT with a bossed membrane

Wang Mengli*, Chen Jingkuang, Cheng Xiaoyang, Li Chuan, Liu Xueyuan

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations


This paper describes the fabrication and characterization of surface-micromachined capacitive ultrasonic transducers with a bossed membrane. The boss was formed using 3μm thick deposited tetraethoxysilane (TEOS) oxide on top of a suspended polysilicon membrane. This same oxide layer was also used to seal the release holes along the peripheral of the polysilicon membrane. No extra mask or processing step in addition to that used for fabricating planar-membrane capacitive micromachined ultrasonic transducer (CMUT) is needed for the addition of a boss on the polysilicon membrane. It was found from device characterization that a bossed device shifted the center frequency to a higher value, improved the fractional bandwidth in transmission mode, increased the receiver sensitivity, and augmented the electromechanical coupling efficiency compared to their planar-membrane counterpart with the same membrane diameter.

Original languageEnglish
Article number4803574
Pages (from-to)394-397
Number of pages4
JournalProceedings of the IEEE Ultrasonics Symposium
StatePublished - 2008
Event2008 IEEE International Ultrasonics Symposium, IUS 2008 - Beijing, China
Duration: 2 Nov 20085 Nov 2008


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