Effect of negative ions generation from sputtering target on crystalline orientation and kt2 of ScAlN thin films

Rui Kihara; Shinji Takayanagi; Takahiko Yanagitani

doi:10.1109/ULTSYM.2019.8925983

Effect of negative ions generation from sputtering target on crystalline orientation and k_t² of ScAlN thin films

Rui Kihara, Shinji Takayanagi, Takahiko Yanagitani

School of Advanced Science and Engineering

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

4 Citations (Scopus)

Abstract

Large electromechanical coupling coefficient k_t² of the piezoelectric thin film is required for wide band operation in the bulk acoustic wave (BAW) filter. k_t² of AlN thin film was greatly improved by Sc doping. Sc metal usually contains carbon and oxygen impurities. Therefore, CN^- and O^- negative ions are generated from Sc sputtering target. As a result, crystalline orientation is degraded due to these negative ions bombardment to the substrate. We know that negative ions generation increase with increasing target temperature. In this study, to suppress negative ions generation from the target, Sc grains were embedded in water cooled Al metal disc target. ScAlN thin films were grown by RF magnetron sputtering. Two types of targets, where Sc grains are just put (heated) or those are embedded (cooled), are compared.

Original language	English
Title of host publication	2019 IEEE International Ultrasonics Symposium, IUS 2019
Publisher	IEEE Computer Society
Pages	1120-1123
Number of pages	4
ISBN (Electronic)	9781728145969
DOIs	https://doi.org/10.1109/ULTSYM.2019.8925983
Publication status	Published - 2019 Oct
Event	2019 IEEE International Ultrasonics Symposium, IUS 2019 - Glasgow, United Kingdom Duration: 2019 Oct 6 → 2019 Oct 9

Publication series

Name	IEEE International Ultrasonics Symposium, IUS
Volume	2019-October
ISSN (Print)	1948-5719
ISSN (Electronic)	1948-5727

Conference

Conference	2019 IEEE International Ultrasonics Symposium, IUS 2019
Country/Territory	United Kingdom
City	Glasgow
Period	19/10/6 → 19/10/9

Keywords

ScAlN
crystalline orientation
electromechanical coupling coefficient
negative ion
piezoelectric thin film

ASJC Scopus subject areas

Acoustics and Ultrasonics

Access to Document

10.1109/ULTSYM.2019.8925983

Cite this

Kihara, R., Takayanagi, S., & Yanagitani, T. (2019). Effect of negative ions generation from sputtering target on crystalline orientation and k_t² of ScAlN thin films. In 2019 IEEE International Ultrasonics Symposium, IUS 2019 (pp. 1120-1123). [8925983] (IEEE International Ultrasonics Symposium, IUS; Vol. 2019-October). IEEE Computer Society. https://doi.org/10.1109/ULTSYM.2019.8925983

Effect of negative ions generation from sputtering target on crystalline orientation and k_t² of ScAlN thin films. / Kihara, Rui; Takayanagi, Shinji; Yanagitani, Takahiko.

2019 IEEE International Ultrasonics Symposium, IUS 2019. IEEE Computer Society, 2019. p. 1120-1123 8925983 (IEEE International Ultrasonics Symposium, IUS; Vol. 2019-October).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Kihara, R, Takayanagi, S & Yanagitani, T 2019, Effect of negative ions generation from sputtering target on crystalline orientation and k_t² of ScAlN thin films. in 2019 IEEE International Ultrasonics Symposium, IUS 2019., 8925983, IEEE International Ultrasonics Symposium, IUS, vol. 2019-October, IEEE Computer Society, pp. 1120-1123, 2019 IEEE International Ultrasonics Symposium, IUS 2019, Glasgow, United Kingdom, 19/10/6. https://doi.org/10.1109/ULTSYM.2019.8925983

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title = "Effect of negative ions generation from sputtering target on crystalline orientation and kt2 of ScAlN thin films",

abstract = "Large electromechanical coupling coefficient kt2 of the piezoelectric thin film is required for wide band operation in the bulk acoustic wave (BAW) filter. kt2 of AlN thin film was greatly improved by Sc doping. Sc metal usually contains carbon and oxygen impurities. Therefore, CN- and O- negative ions are generated from Sc sputtering target. As a result, crystalline orientation is degraded due to these negative ions bombardment to the substrate. We know that negative ions generation increase with increasing target temperature. In this study, to suppress negative ions generation from the target, Sc grains were embedded in water cooled Al metal disc target. ScAlN thin films were grown by RF magnetron sputtering. Two types of targets, where Sc grains are just put (heated) or those are embedded (cooled), are compared.",

keywords = "ScAlN, crystalline orientation, electromechanical coupling coefficient, negative ion, piezoelectric thin film",

author = "Rui Kihara and Shinji Takayanagi and Takahiko Yanagitani",

note = "Funding Information: ACKNOWLEDGMENT This work was supported by the JST PRESTO (No. JPMJPR16R8), and KAKENHI (Grant-in-Aid for Scientific Research No.16H04356, No. 19H02202, and No. 18K19037). Publisher Copyright: {\textcopyright} 2019 IEEE.; 2019 IEEE International Ultrasonics Symposium, IUS 2019 ; Conference date: 06-10-2019 Through 09-10-2019",

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