MEMS
MEMS (Micro Electro Mechanical Systems) devices are now used in a wide range of applications (medical, geolocation, automotive, aerospace, etc.) as active or passive systems (wave transmitters, sensors, filters, etc.). The manufacture of these devices requires highly specialized methods of fabrication and structuring at the micrometer scale, which largely determine both the choice of materials and the technological processes needed to produce the device’s active components (levers, membranes, bridges, etc.). The development of MEMS devices has largely been driven by the adoption of standards from microelectronics component technology. Consequently, most MEMS devices currently on the market (at least those in the civilian sector) are fabricated from materials compatible with the CMOS process: silicon, silicon nitride, silicon oxide, etc. Nevertheless, these materials have physical limitations, particularly when used in certain so-called hostile environments. Some of these environments are strategic in nature (such as the nuclear sector and the issue of radioactive waste storage, or the aerospace sector and the challenge of flow control on aircraft) and involve matters of national and/or European sovereignty. Due to their physical properties (high thermal conductivity, chemical inertness, and resistance to radiation, among others), wide-bandgap semiconductors (SiC, diamond, GaN, etc.) are now highly promising candidates for overcoming the limitations of currently used materials.
Several years ago, CRHEA began developing SiC- and GaN-based structures to demonstrate the potential of these materials for the fabrication of MEMS capable of operating in harsh environments. This work has demonstrated the effectiveness of SiC in fabricating CMUTs (Capacitive Micromachined Ultrasonic Transducers),[1] as well as micro-cantilevers capable of detecting very low concentrations of hydrogen, below 0.5%.[2]
CRHEA has already partnered on several projects focused on MEMS sensors (MEMSGaN, NEMSGaN, H2MEMS) and is currently serving as a supplier of heterostructures made from these same materials as part of the ANR MIGNON project and the RESISTE targeted project under the PEPR Electronics program. By positioning itself as a key supplier of the building blocks for this nationally significant program, the team is showcasing its recognized expertise and intends to sustain it.
- [1] - Designing SiC Based CMUT Structures: An Original Approach and Related Material Issues
Materials Science Forum Vol. 1062, 94 (2022) – https://doi.org/10.4028/p-00832x - [2] - A New Approach in the Field of Hydrogen Gas Sensing Using MEMS Based 3C-SiC Microcantilevers
Materials Science Forum Vol. 1062, 593 (2022) – https://doi.org/10.4028/p-m048qs
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