A three-mask process for fabricating vacuum-sealed capacitive micromachined ultrasonic transducers using anodic bonding

This paper introduces a simplified fabrication method for vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using anodic bonding. Anodic bonding provides the established advantages of wafer-bondingbased CMUT fabrication processes, including process simplicity, control over p...

Ausführliche Beschreibung

Bibliographische Detailangaben
Veröffentlicht in:IEEE transactions on ultrasonics, ferroelectrics, and frequency control. - 1986. - 62(2015), 5 vom: 14. Mai, Seite 972-82
1. Verfasser: Yamaner, F Yalçın (VerfasserIn)
Weitere Verfasser: Zhang, Xiao, Oralkan, Ömer
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2015
Zugriff auf das übergeordnete Werk:IEEE transactions on ultrasonics, ferroelectrics, and frequency control
Schlagworte:Journal Article Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Silicon Compounds silicon nitride QHB8T06IDK
LEADER 01000caa a22002652c 4500
001 NLM248929984
003 DE-627
005 20250218124748.0
007 cr uuu---uuuuu
008 231224s2015 xx |||||o 00| ||eng c
024 7 |a 10.1109/TUFFC.2014.006794  |2 doi 
028 5 2 |a pubmed25n0829.xml 
035 |a (DE-627)NLM248929984 
035 |a (NLM)25965687 
040 |a DE-627  |b ger  |c DE-627  |e rakwb 
041 |a eng 
100 1 |a Yamaner, F Yalçın  |e verfasserin  |4 aut 
245 1 2 |a A three-mask process for fabricating vacuum-sealed capacitive micromachined ultrasonic transducers using anodic bonding 
264 1 |c 2015 
336 |a Text  |b txt  |2 rdacontent 
337 |a ƒaComputermedien  |b c  |2 rdamedia 
338 |a ƒa Online-Ressource  |b cr  |2 rdacarrier 
500 |a Date Completed 02.02.2016 
500 |a Date Revised 25.09.2018 
500 |a published: Print 
500 |a Citation Status MEDLINE 
520 |a This paper introduces a simplified fabrication method for vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using anodic bonding. Anodic bonding provides the established advantages of wafer-bondingbased CMUT fabrication processes, including process simplicity, control over plate thickness and properties, high fill factor, and ability to implement large vibrating cells. In addition to these, compared with fusion bonding, anodic bonding can be performed at lower processing temperatures, i.e., 350°C as opposed to 1100°C; surface roughness requirement for anodic bonding is more than 10 times more relaxed, i.e., 5-nm rootmean- square (RMS) roughness as opposed to 0.5 nm for fusion bonding; anodic bonding can be performed on smaller contact area and hence improves the fill factor for CMUTs. Although anodic bonding has been previously used for CMUT fabrication, a CMUT with a vacuum cavity could not have been achieved, mainly because gas is trapped inside the cavities during anodic bonding. In the approach we present in this paper, the vacuum cavity is achieved by opening a channel in the plate structure to evacuate the trapped gas and subsequently sealing this channel by conformal silicon nitride deposition in the vacuum environment. The plate structure of the fabricated CMUT consists of the single-crystal silicon device layer of a silicon-on-insulator wafer and a thin silicon nitride insulation layer. The presented fabrication approach employs only three photolithographic steps and combines the advantages of anodic bonding with the advantages of a patterned metal bottom electrode on an insulating substrate, specifically low parasitic series resistance and low parasitic shunt capacitance. In this paper, the developed fabrication scheme is described in detail, including process recipes. The fabricated transducers are characterized using electrical input impedance measurements in air and hydrophone measurements in immersion. A representative design is used to demonstrate immersion operation in conventional, collapse-snapback, and collapse modes. In collapsemode operation, an output pressure of 1.67 MPa pp is shown at 7 MHz on the surface of the transducer for 60-Vpp, 3-cycle sinusoidal excitation at 30-V dc bias 
650 4 |a Journal Article 
650 4 |a Research Support, N.I.H., Extramural 
650 4 |a Research Support, Non-U.S. Gov't 
650 4 |a Research Support, U.S. Gov't, Non-P.H.S. 
650 7 |a Silicon Compounds  |2 NLM 
650 7 |a silicon nitride  |2 NLM 
650 7 |a QHB8T06IDK  |2 NLM 
700 1 |a Zhang, Xiao  |e verfasserin  |4 aut 
700 1 |a Oralkan, Ömer  |e verfasserin  |4 aut 
773 0 8 |i Enthalten in  |t IEEE transactions on ultrasonics, ferroelectrics, and frequency control  |d 1986  |g 62(2015), 5 vom: 14. Mai, Seite 972-82  |w (DE-627)NLM098181017  |x 1525-8955  |7 nnas 
773 1 8 |g volume:62  |g year:2015  |g number:5  |g day:14  |g month:05  |g pages:972-82 
856 4 0 |u http://dx.doi.org/10.1109/TUFFC.2014.006794  |3 Volltext 
912 |a GBV_USEFLAG_A 
912 |a SYSFLAG_A 
912 |a GBV_NLM 
912 |a GBV_ILN_22 
912 |a GBV_ILN_24 
912 |a GBV_ILN_350 
951 |a AR 
952 |d 62  |j 2015  |e 5  |b 14  |c 05  |h 972-82