Wafer-scale Fabrication of Nanometer Silicon Posts for Capacitive Micromachined Ultrasonic Transducers with Substrate-Embedded Springs
| Autor: | Butrus T. Khuri-Yakub, Dong-Hyun Kang, Hae Youn Kim, Byung Chul Lee, Jinsik Kim |
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| Rok vydání: | 2020 |
| Předmět: |
0303 health sciences
Fabrication Materials science Silicon business.industry chemistry.chemical_element 02 engineering and technology 021001 nanoscience & nanotechnology law.invention 03 medical and health sciences Capacitive micromachined ultrasonic transducers chemistry law Deep reactive-ion etching Optoelectronics Wafer Ultrasonic sensor Photolithography Photomask 0210 nano-technology business 030304 developmental biology |
| Zdroj: | 2020 IEEE International Ultrasonics Symposium (IUS). |
| DOI: | 10.1109/ius46767.2020.9251528 |
| Popis: | A capacitive micromachined ultrasonic transducer (CMUT) with substrate-embedded springs has been demonstrated high transmit efficiency with non-flexural parallel-plate piston movement. In this paper, we introduce whole wafer-scale uniform nanometer silicon posts with a fabrication technique of combination between DRIE and RIE. In order to maintain our fabrication cost-effective, a photomask with a minimum feature size of $2.0\ \mu m$ was used for whole wafer-scale photolithography, and a size-reduced RIE process followed by DRIE was conducted for achieving the sub-micron or nanometer post area. Furthermore, In-situ nanomechanical tests of the fabricated silicon posts were conducted using a pico-indenter (PI 85L Pico-Indenter, Bruker) monitored under a scanning electron microscopy. The length and the diameter of the silicon post after size-reduction by RIE are measured as $5.6\ \mu m$ and .74\ \mu m$ , respectively. The uniformity across the whole 4-inch wafer is less than 5%. The loading-unloading graph by In-situ nanomechanical experiments confirmed that the silicon posts could consistently achieve above 6% elastic strain. We are currently applying this nanometer springs to the CMUTs with substrate-embedded springs. |
| Databáze: | OpenAIRE |
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