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 Cohen, Sergey Khodorov, Yishay Feldman, Anna Kossoy, Ifat Kaplan-Ashiri, Anatoly Frenkel, Ellen Wachtel, Igor Lubomirsky*, David Ehre*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
101 Downloads (Pure)

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 α-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.<br />
Original languageEnglish
Article number7041
Pages (from-to)1-16
Number of pages16
JournalSensors (Basel, Switzerland)
Volume22
Issue number18
DOIs
Publication statusPublished - 17 Sept 2022

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.

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