bb593a0fe0dd34ded8b165eb2a87d800 sensors_a2021v21n24p8447.pdf b728421603db271d573c14f3f74721ba138d0482 sensors_a2021v21n24p8447.pdf 32bb10ec936b6eb3bcec1b154c004e33fe26d8601e03cd60768e200c78708282 sensors_a2021v21n24p8447.pdf Title: Enhancing AlN PMUTs’ Acoustic Responsivity within a MEMS-on-CMOS Process Subject: In this paper, guidelines for the optimization of piezoelectrical micromachined ultrasound transducers (PMUTs) monolithically integrated over a CMOS technology are developed. Higher acoustic pressure is produced by PMUTs with a thin layer of AlN piezoelectrical material and Si3N4 as a passive layer, as is studied here with finite element modeling (FEM) simulations and experimental characterization. Due to the thin layers used, parameters such as residual stress become relevant as they produce a buckled structure. It has been reported that the buckling of the membrane due to residual stress, in general, reduces the coupling factor and consequently degrades the efficiency of the acoustic pressure production. In this paper, we show that this buckling can be beneficial and that the fabricated PMUTs exhibit enhanced performance depending on the placement of the electrodes. This behavior was demonstrated experimentally and through FEM. The acoustic characterization of the fabricated PMUTs shows the enhancement of the PMUT performance as a transmitter (with 5 kPa V-1 surface pressure for a single PMUT) and as a receiver (12.5 V MPa-1) in comparison with previously reported devices using the same MEMS-on-CMOS technology as well as state-of-the-art devices. Keywords: PMUT; ultrasound; CMOS; MEMS-on-CMOS; acoustic responsivity; AlN; piezoelectric transducers; PMUT-on-CMOS Author: Eyglis Ledesma, Ivan Zamora, Arantxa Uranga, Francesc Torres and Núria Barniol Creator: LaTeX with hyperref Producer: pdfTeX-1.40.21 CreationDate: Fri Dec 17 14:43:22 2021 CET ModDate: Fri Dec 17 16:20:13 2021 CET Tagged: no UserProperties: no Suspects: no Form: none JavaScript: no Pages: 12 Encrypted: no Page size: 595.276 x 841.89 pts (A4) Page rot: 0 File size: 5244637 bytes Optimized: no PDF version: 1.7 name type encoding emb sub uni object ID ------------------------------------ ----------------- ---------------- --- --- --- --------- IYGODB+URWPalladioL-Ital Type 1 Custom yes yes no 10 0 OQTDAM+URWPalladioL-Bold Type 1 Custom yes yes no 15 0 BBHRJF+URWPalladioL-Roma Type 1 Custom yes yes no 19 0 GXLBWK+CMSY10 Type 1 Builtin yes yes no 23 0 ENLEMO+VnURWPalladioL-Bold Type 1 Custom yes yes no 27 0 XHDYZV+VnURWPalladioL Type 1 Custom yes yes no 32 0 RVSEMT+TimesNewRomanPS-BoldItalicMT Type 1C WinAnsi yes yes no 40 0 MCBCCI+SourceSansRoman-Regular Type 1C Custom yes yes no 62 0 MCBCCM+SourceSansRoman.613wght Type 1C Custom yes yes no 66 0 MCBCCO+SourceSansRoman-Bold Type 1C Custom yes yes no 70 0 HREAIJ+EURM10 Type 1 Builtin yes yes no 82 0 WMGRYN+CMEX10 Type 1 Builtin yes yes no 89 0 CZKGAS+CMR10 Type 1 Builtin yes yes no 93 0 QQXUPP+PazoMath Type 1 Builtin yes yes no 97 0 XIRVNA+EURB10 Type 1 Builtin yes yes no 104 0 Jhove (Rel. 1.22.1, 2019-04-17) Date: 2023-05-27 03:27:04 CEST RepresentationInformation: sensors_a2021v21n24p8447.pdf ReportingModule: PDF-hul, Rel. 1.12.1 (2019-04-17) LastModified: 2023-03-31 11:58:44 CEST Size: 5244637 Format: PDF Version: 1.7 Status: Well-Formed and valid SignatureMatches: PDF-hul MIMEtype: application/pdf PDFMetadata: Objects: 303 FreeObjects: 1 IncrementalUpdates: 0 DocumentCatalog: PageLayout: SinglePage PageMode: UseNone Outlines: Item: Title: Introduction Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@44c8afef Item: Title: Materials and Methods: Optimization of PMUT Transducer Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@7b69c6ba Item: Title: Experimental Results Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@46daef40 Children: Item: Title: PMUTs Fabrication and Electrical Characterization Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@12f41634 Item: Title: Acoustic Characterization Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@13c27452 Item: Title: Discussion and Conclusions Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@262b2c86 Item: Title: References Destination: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject@371a67ec Info: Title: Enhancing AlN PMUTs’ Acoustic Responsivity within a MEMS-on-CMOS Process Author: Eyglis Ledesma, Ivan Zamora, Arantxa Uranga, Francesc Torres and Núria Barniol Subject: In this paper, guidelines for the optimization of piezoelectrical micromachined ultrasound transducers (PMUTs) monolithically integrated over a CMOS technology are developed. Higher acoustic pressure is produced by PMUTs with a thin layer of AlN piezoelectrical material and Si3N4 as a passive layer, as is studied here with finite element modeling (FEM) simulations and experimental characterization. Due to the thin layers used, parameters such as residual stress become relevant as they produce a buckled structure. It has been reported that the buckling of the membrane due to residual stress, in general, reduces the coupling factor and consequently degrades the efficiency of the acoustic pressure production. In this paper, we show that this buckling can be beneficial and that the fabricated PMUTs exhibit enhanced performance depending on the placement of the electrodes. This behavior was demonstrated experimentally and through FEM. The acoustic characterization of the fabricated PMUTs shows the enhancement of the PMUT performance as a transmitter (with 5 kPa V-1 surface pressure for a single PMUT) and as a receiver (12.5 V MPa-1) in comparison with previously reported devices using the same MEMS-on-CMOS technology as well as state-of-the-art devices. 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