Minimizing residual stress of aluminum nitride (AlN) thin films using multi-step deposition of DC pulsed sputtering

Chen, Wei‐Lun; Yang, Shang Shian; Yuan, Ning Hsiu; Zhou, Wei Yu; Yang, Yu-Pu; Lo, Hsiao-Han; Wang, Peter J.; Lai, Walter; Fuh, Yiin Kuen; Li, Tomi T.

doi:10.1109/cstic55103.2022.9856787

Cited by 2 publications

(2 citation statements)

References 18 publications

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“…However, AlN PMUTs based on MEMS process is sensitive to stress due to their inherent characteristics resulting from the suspended structure made of multi-layered thin films. Residual stress in AlN film still poses a significant challenge [10]. Additionally, considering subsequent steps during its package and assembly, different functional materials such as acoustic matching material and water sealing being used, the difficulty in stress control and design of PMUT further increases.…”

Section: Introductionmentioning

confidence: 99%

Design, Fabrication, Characterization and Simulation of AlN PMUT for Sonar Imaging Applications

Chen,

Ma,

Lai

et al. 2024

Preprint

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To address the requirements of sonar imaging, such as high receiving sensitivity, wide bandwidth, wide receiving angle, an AlN PMUT with an optimized ratio of 0.6 for the piezoelectric layer diameter to backside cavity diameter is proposed in this paper. A sample AlN PMUT is designed and fabricated with SOI substrate-based bulk MEMS process. The characterization test result of the sample demonstrates a -6 dB bandwidth of approximately 500 kHz and a measured receiving sensitivity per unit area of at 1.37 V/μPa/mm2, which significantly surpasses the performance of previously reported PMUTs. The -6 dB horizontal angles of the AlN PMUT at 300 kHz and 500 kHz are measured 68.30° and 54.24°, respectively. To achieve an accurate prediction of its characteristics when being packaged and assembled in a receive array, numerical simulations with the consideration of film stress are conducted. The numerical result shows a maximum deviation of ±7% in the underwater receiving sensitivity across the frequency range of 200 kHz to 1000 kHz and a deviation of about 0.33% in the peak of underwater receiving sensitivity comparing to the experimental data. By such good agreement, the simulation method reveals its capability of providing theoretical foundation for enhancing the uniformity of the AlN PMUTs in future studies.

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Section: Introductionmentioning

confidence: 99%

Design, Fabrication, Characterization and Simulation of AlN PMUT for Sonar Imaging Applications

Chen,

Ma,

Lai

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…However, AlN PMUTs based on the MEMS process are sensitive to stress due to their inherent characteristics resulting from the suspended structure made of multi-layered thin films. Residual stress in an AlN film still poses a significant challenge [ 10 ]. Additionally, considering subsequent steps during its packaging and assembly, when different functional materials such as acoustic matching material and water sealing are used, the difficulty of controlling stress and designing a PMUT further increases.…”

Section: Introductionmentioning

confidence: 99%

Design, Fabrication, Characterization, and Simulation of AlN-Based Piezoelectric Micromachined Ultrasonic Transducer for Sonar Imaging Applications

Chen,

Ma,

Lai

et al. 2024

Micromachines

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To address the requirements of sonar imaging, such as high receiving sensitivity, a wide bandwidth, and a wide receiving angle, an AlN PMUT with an optimized ratio of 0.6 for the piezoelectric layer diameter to backside cavity diameter is proposed in this paper. A sample AlN PMUT is designed and fabricated with the SOI substrate-based bulk MEMS process. The characterization test result of the sample demonstrates a −6 dB bandwidth of approximately 500 kHz and a measured receiving sensitivity per unit area of 1.37 V/μPa/mm2, which significantly surpasses the performance of previously reported PMUTs. The −6 dB horizontal angles of the AlN PMUT at 300 kHz and 500 kHz are measured as 68.30° and 54.24°, respectively. To achieve an accurate prediction of its characteristics when being packaged and assembled in a receive array, numerical simulations with the consideration of film stress are conducted. The numerical result shows a maximum deviation of ±7% in the underwater receiving sensitivity across the frequency range of 200 kHz to 1000 kHz and a deviation of about 0.33% in the peak of underwater receiving sensitivity compared to the experimental data. By such good agreement, the simulation method reveals its capability of providing theoretical foundation for enhancing the uniformity of AlN PMUTs in future studies.

show abstract

Minimizing residual stress of aluminum nitride (AlN) thin films using multi-step deposition of DC pulsed sputtering

Cited by 2 publications

References 18 publications

Design, Fabrication, Characterization and Simulation of AlN PMUT for Sonar Imaging Applications

Design, Fabrication, Characterization and Simulation of AlN PMUT for Sonar Imaging Applications

Design, Fabrication, Characterization, and Simulation of AlN-Based Piezoelectric Micromachined Ultrasonic Transducer for Sonar Imaging Applications

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