C-Axis Textured, 2–3 μm Thick Al0.75Sc0.25N Films Grown on Chemically Formed TiN/Ti Seeding Layers for MEMS Applications

Asaf Cohen; Hagai Cohen; Sidney R. Cohen; Sergey Khodorov; Yishay Feldman; Anna Kossoy; Ifat Kaplan-Ashiri; Anatoly Frenkel; Ellen Wachtel; Igor Lubomirsky; David Ehre

doi:10.3390/s22187041

C-Axis Textured, 2–3 μm Thick Al_0.75Sc_0.25N Films Grown on Chemically Formed TiN/Ti Seeding Layers for MEMS Applications

Asaf Cohen, Hagai Cohen, Sidney R. Cohen, Sergey Khodorov, Yishay Feldman, Anna Kossoy, Ifat Kaplan-Ashiri, Anatoly Frenkel, Ellen Wachtel, Igor Lubomirsky, David Ehre

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

A protocol for successfully depositing [001] textured, 2–3 µm thick films of Al_0.75Sc_0.25N, is proposed. The procedure relies on the fact that sputtered Ti is [001]-textured (Formula presented.) -phase (hcp). Diffusion of nitrogen ions into the α-Ti film during reactive sputtering of Al_0.75,Sc_0.25N likely forms a [111]-oriented TiN intermediate layer. The lattice mismatch of this very thin film with Al_0.75Sc_0.25N is ~3.7%, providing excellent conditions for epitaxial growth. In contrast to earlier reports, the Al_0.75Sc_0.25N films prepared in the current study are Al-terminated. Low growth stress (<100 MPa) allows films up to 3 µm thick to be deposited without loss of orientation or decrease in piezoelectric coefficient. An advantage of the proposed technique is that it is compatible with a variety of substrates commonly used for actuators or MEMS, as demonstrated here for both Si wafers and D263 borosilicate glass. Additionally, thicker films can potentially lead to increased piezoelectric stress/strain by supporting application of higher voltage, but without increase in the magnitude of the electric field.

Original language	English
Article number	7041
Journal	Sensors
Volume	22
Issue number	18
DOIs	https://doi.org/10.3390/s22187041
State	Published - 17 Sep 2022
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2022 by the authors.

Funding

This work was supported by NATO Science for Peace award G5453, and, in part, by the BioWings project, which has received funding from the European Union Horizon 2020 under the Future and Emerging Technologies (FET) program with grant agreement No 801267. IL and AIF acknowledge the NSF-BSF program grant 2018717. AIF acknowledges support by U.S. National Science Foundation Grant number DMR-1911592.

Funders	Funder number
NATO Science for Peace	G5453
NSF-BSF	2018717
National Science Foundation	DMR-1911592
H2020 Future and Emerging Technologies	801267
Horizon 2020

Keywords

aluminum scandium nitride
piezoelectric
seeding layer
sputtering
texture

Access to Document

10.3390/s22187041

Cite this

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title = "C-Axis Textured, 2–3 μm Thick Al0.75Sc0.25N Films Grown on Chemically Formed TiN/Ti Seeding Layers for MEMS Applications",

abstract = "A protocol for successfully depositing [001] textured, 2–3 µm thick films of Al0.75Sc0.25N, is proposed. The procedure relies on the fact that sputtered Ti is [001]-textured (Formula presented.) -phase (hcp). Diffusion of nitrogen ions into the α-Ti film during reactive sputtering of Al0.75,Sc0.25N likely forms a [111]-oriented TiN intermediate layer. The lattice mismatch of this very thin film with Al0.75Sc0.25N is ~3.7%, providing excellent conditions for epitaxial growth. In contrast to earlier reports, the Al0.75Sc0.25N films prepared in the current study are Al-terminated. Low growth stress (<100 MPa) allows films up to 3 µm thick to be deposited without loss of orientation or decrease in piezoelectric coefficient. An advantage of the proposed technique is that it is compatible with a variety of substrates commonly used for actuators or MEMS, as demonstrated here for both Si wafers and D263 borosilicate glass. Additionally, thicker films can potentially lead to increased piezoelectric stress/strain by supporting application of higher voltage, but without increase in the magnitude of the electric field.",

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AU - Cohen, Sidney R.

AU - Khodorov, Sergey

AU - Feldman, Yishay

AU - Kossoy, Anna

AU - Kaplan-Ashiri, Ifat

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AU - Wachtel, Ellen

AU - Lubomirsky, Igor

AU - Ehre, David

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