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Capacitive micromachined ultrasonic transducers: fabrication technology
Arif Sanli Ergun1, Yongli Huang, Xuefeng Zhuang
1Edward L. Ginzton Laboratory, Stanford University, Stanford, CA 94305-4088, USA. sanli@stanford.edu
Summary
Capacitive micromachined ultrasonic transducer (cMUT) fabrication is advancing. The wafer-bonding method offers superior control, yield, and uniformity compared to sacrificial release processes for cMUT devices.
Area of Science:
- Materials Science
- Electrical Engineering
- Acoustics
Background:
- Capacitive micromachined ultrasonic transducer (cMUT) technology is crucial for advanced imaging systems.
- Growing interest from medical, underwater imaging, and nondestructive evaluation (NDE) sectors.
- cMUTs are poised to significantly impact volumetric imaging and commercial applications.
Purpose of the Study:
- To review and compare fabrication technologies for cMUTs.
- To detail two primary fabrication approaches: sacrificial release and wafer-bonding.
- To evaluate process variations for optimal cMUT manufacturing.
Main Methods:
- Detailed review of sacrificial release processes for cMUT fabrication.
- In-depth description of the novel wafer-bonding method for cMUTs.
- Qualitative and quantitative comparison of different cMUT process variations.
Main Results:
- Wafer-bonded cMUT technology demonstrates superior process control, yield, and uniformity.
- The wafer-bonding method reduces fabrication steps (six-mask to four-mask process).
- Significant improvement in turn-around time due to streamlined wafer-bonding process.
Conclusions:
- Wafer-bonded cMUTs represent an advancement in fabrication technology.
- The improved process control and efficiency of wafer-bonding are key advantages.
- This method enhances the feasibility of cMUTs for next-generation imaging and NDE applications.
