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Sputtered Piezoelectric AlN Thin Films: Parameter Optimisation, Deposition Challenges, and Emerging Perspectives—A Review

delete2026-08-01
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OA
AI
R
Rangaraajan Muralidaran
P
Paritosh Dubey
K
Kuldeep Singh Gour
S
Shuvam Pawar
V
Vinod Belwanshi *
J
Jacopo Iannacci *
DOI:10.3390/mi17080919delete
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Abstract

Abstract

En 中文
This article reviews the reactive magnetron sputtering of piezoelectric Aluminium Nitride (AlN) thin films, with a focus on process parameter optimisation and system-level deposition challenges. AlN is a leading material for MEMS and RF applications owing to its c-axis (002) orientation, high acoustic velocity, wide bandgap (∼6.2 eV), and CMOS compatibility. We review the influence of sputtering power, nitrogen flow ratio, substrate temperature, and target-to-substrate distance on crystallographic quality and document practical hardware challenges, including vacuum leakage, grounding faults, target erosion, and mass flow controller drift, that critically affect reproducibility but are systematically underreported in the literature. A perspective is provided on emerging application domains where optimised AlN films address current performance gaps, including next-generation RF/telecom systems towards 6G and Future Networks, harsh environment sensing and actuation, biomedical ultrasound, and IoT energy harvesting. The complementarity between AlN and Silicon Carbide (SiC) is discussed for high-temperature, high-power, and radiation-hard MEMS, where AlN/SiC heterostructures combine the piezoelectric activity of AlN with the mechanical and chemical robustness of SiC. It also incorporates a discussion of dopant- and heteroepitaxy-based AlN engineering, AlN deposition on a wider range of substrates, the role of seed and electrode underlayers, and pulsed-DC sputtering as a third power supply mode alongside RF and conventional DC.
Keywords:
reactive magnetron sputter deposition
AlN thin films
piezoelectric materials
RF-MEMS
6G
Silicon Carbide

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Micromachines cover
Micromachines
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3
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C
csir-national metallurgical laboratory
Scholars:
80
Papers: 43
Citations: 0
A
academy of scientific and innovative research
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260
Papers: 117
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F
Fondazione Bruno Kessler
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Papers: 1.6K
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National Institute of Technology Warangal
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