ScAlN thick film ultrasonic transducer in 40 MHz–80 MHz

Ko hei Sano, Rei Karasawa, Takahiko Yanagitani

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    A medical ultrasound diagnostic system and an ultrasonic microscope are generally used in the frequency range of 1 MHz – 20 MHz and 100 MHz – 2 GHz, respectively. Ultrasonic transducers in the frequency range of 20 MHz – 100 MHz are, therefore, not well-developed because of less applications into ultrasonic imaging or suitable piezoelectric materials with this frequency range. PVDF are usually used for ultrasonic transducers in the 10 MHz – 50 MHz ranges. However, their electromechanical coupling coefficient kt 2 of 4% is not enough for the practical uses. In order to excite ultrasonic wave in the 20 MHz – 100 MHz, 125μm – 25μm thick piezoelectric film is required when the longitudinal velocity of material is assumed to be 5000 m/s. However, it is difficult to grow such a thick piezoelectric film without a crack being caused by the internal stress during the dry deposition technique. We achieved stress free film growth by employing the unique hot target sputtering technique without heating substrate. High efficient 81 MHz (kt 2=18.5%) and 43 MHz (kt 2=15.2%) ultrasonic generation by using the 43 m and 90 m extremely thick ScAlN (Sc:39%) films were demonstrated, respectively. We discussed the advantage of ScAlN thick film transducers by comparing them with conventional PVDF transducer for water medium.

    Original languageEnglish
    JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
    DOIs
    Publication statusAccepted/In press - 2018 Aug 23

    Fingerprint

    Ultrasonic transducers
    Thick films
    thick films
    transducers
    ultrasonics
    Ultrasonics
    Transducers
    frequency ranges
    Ultrasonic imaging
    Electromechanical coupling
    Piezoelectric materials
    Ultrasonic waves
    Film growth
    Sputtering
    Residual stresses
    Microscopes
    Cracks
    Heating
    ultrasonic radiation
    coupling coefficients

    Keywords

    • Acoustics
    • Frequency control
    • Piezoelectric films
    • Piezoelectric films
    • Piezoelectric resonators
    • ScAlN
    • Sputtering
    • Substrates
    • Thick films
    • thick piezoelectric film
    • Transducers
    • ultrasonic transducer
    • Ultrasonic transducers

    ASJC Scopus subject areas

    • Instrumentation
    • Acoustics and Ultrasonics
    • Electrical and Electronic Engineering

    Cite this

    @article{4a2479838d00443ca3dbbf5cebd9f224,
    title = "ScAlN thick film ultrasonic transducer in 40 MHz–80 MHz",
    abstract = "A medical ultrasound diagnostic system and an ultrasonic microscope are generally used in the frequency range of 1 MHz – 20 MHz and 100 MHz – 2 GHz, respectively. Ultrasonic transducers in the frequency range of 20 MHz – 100 MHz are, therefore, not well-developed because of less applications into ultrasonic imaging or suitable piezoelectric materials with this frequency range. PVDF are usually used for ultrasonic transducers in the 10 MHz – 50 MHz ranges. However, their electromechanical coupling coefficient kt 2 of 4{\%} is not enough for the practical uses. In order to excite ultrasonic wave in the 20 MHz – 100 MHz, 125μm – 25μm thick piezoelectric film is required when the longitudinal velocity of material is assumed to be 5000 m/s. However, it is difficult to grow such a thick piezoelectric film without a crack being caused by the internal stress during the dry deposition technique. We achieved stress free film growth by employing the unique hot target sputtering technique without heating substrate. High efficient 81 MHz (kt 2=18.5{\%}) and 43 MHz (kt 2=15.2{\%}) ultrasonic generation by using the 43 m and 90 m extremely thick ScAlN (Sc:39{\%}) films were demonstrated, respectively. We discussed the advantage of ScAlN thick film transducers by comparing them with conventional PVDF transducer for water medium.",
    keywords = "Acoustics, Frequency control, Piezoelectric films, Piezoelectric films, Piezoelectric resonators, ScAlN, Sputtering, Substrates, Thick films, thick piezoelectric film, Transducers, ultrasonic transducer, Ultrasonic transducers",
    author = "Sano, {Ko hei} and Rei Karasawa and Takahiko Yanagitani",
    year = "2018",
    month = "8",
    day = "23",
    doi = "10.1109/TUFFC.2018.2865791",
    language = "English",
    journal = "IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control",
    issn = "0885-3010",
    publisher = "Institute of Electrical and Electronics Engineers Inc.",

    }

    TY - JOUR

    T1 - ScAlN thick film ultrasonic transducer in 40 MHz–80 MHz

    AU - Sano, Ko hei

    AU - Karasawa, Rei

    AU - Yanagitani, Takahiko

    PY - 2018/8/23

    Y1 - 2018/8/23

    N2 - A medical ultrasound diagnostic system and an ultrasonic microscope are generally used in the frequency range of 1 MHz – 20 MHz and 100 MHz – 2 GHz, respectively. Ultrasonic transducers in the frequency range of 20 MHz – 100 MHz are, therefore, not well-developed because of less applications into ultrasonic imaging or suitable piezoelectric materials with this frequency range. PVDF are usually used for ultrasonic transducers in the 10 MHz – 50 MHz ranges. However, their electromechanical coupling coefficient kt 2 of 4% is not enough for the practical uses. In order to excite ultrasonic wave in the 20 MHz – 100 MHz, 125μm – 25μm thick piezoelectric film is required when the longitudinal velocity of material is assumed to be 5000 m/s. However, it is difficult to grow such a thick piezoelectric film without a crack being caused by the internal stress during the dry deposition technique. We achieved stress free film growth by employing the unique hot target sputtering technique without heating substrate. High efficient 81 MHz (kt 2=18.5%) and 43 MHz (kt 2=15.2%) ultrasonic generation by using the 43 m and 90 m extremely thick ScAlN (Sc:39%) films were demonstrated, respectively. We discussed the advantage of ScAlN thick film transducers by comparing them with conventional PVDF transducer for water medium.

    AB - A medical ultrasound diagnostic system and an ultrasonic microscope are generally used in the frequency range of 1 MHz – 20 MHz and 100 MHz – 2 GHz, respectively. Ultrasonic transducers in the frequency range of 20 MHz – 100 MHz are, therefore, not well-developed because of less applications into ultrasonic imaging or suitable piezoelectric materials with this frequency range. PVDF are usually used for ultrasonic transducers in the 10 MHz – 50 MHz ranges. However, their electromechanical coupling coefficient kt 2 of 4% is not enough for the practical uses. In order to excite ultrasonic wave in the 20 MHz – 100 MHz, 125μm – 25μm thick piezoelectric film is required when the longitudinal velocity of material is assumed to be 5000 m/s. However, it is difficult to grow such a thick piezoelectric film without a crack being caused by the internal stress during the dry deposition technique. We achieved stress free film growth by employing the unique hot target sputtering technique without heating substrate. High efficient 81 MHz (kt 2=18.5%) and 43 MHz (kt 2=15.2%) ultrasonic generation by using the 43 m and 90 m extremely thick ScAlN (Sc:39%) films were demonstrated, respectively. We discussed the advantage of ScAlN thick film transducers by comparing them with conventional PVDF transducer for water medium.

    KW - Acoustics

    KW - Frequency control

    KW - Piezoelectric films

    KW - Piezoelectric films

    KW - Piezoelectric resonators

    KW - ScAlN

    KW - Sputtering

    KW - Substrates

    KW - Thick films

    KW - thick piezoelectric film

    KW - Transducers

    KW - ultrasonic transducer

    KW - Ultrasonic transducers

    UR - http://www.scopus.com/inward/record.url?scp=85052717887&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=85052717887&partnerID=8YFLogxK

    U2 - 10.1109/TUFFC.2018.2865791

    DO - 10.1109/TUFFC.2018.2865791

    M3 - Article

    JO - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

    JF - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

    SN - 0885-3010

    ER -