Microphone using NEMS gage detection – MADNEMS

This industrial research program aims at the realization of a MEMS microphone sensor, based on an innovative concept and an advanced micro-electronics technology using Si nanowires.

The main target is conception, realization and characterization of a very compact microphone demonstrator. Two kinds of markets will be targeted :
- the market of audio implants, which requires very stringent specifications in terms of dynamic range, consumption and bandwidth and for which MEMS microphones of the state of the art are still to be improved
- the market of consumer electronics (cell phones, PDA, MP3, notebook...) for which we target a very low consumtion and very compact product in order to cut costs compared to the state of the art.

The innovative concept we propose, based on a LETI patent, uses a membrane able to move in the plane of the substrate (contrary to the state of the art in which the membrane moves out of plane) which enables 2 advantages:
- a decorrelation of the acoustic part and the detection part, which enables to optimize them independantly (not possible in the state of the art)
- same fabrication process for both microphones and accelerometers, which enables either to co-integrate these 2 sensors on the same chip or to use the same technological plateform for these 2 components, which is also impossible with the concepts of the state of the art

This new concept also benefits from a strain gage detection using a Si nanwire (NEMS) which enables very high sensitivity et thus enhanced performances and miniaturization, which has never been shown until now and is in perfect adequation with medical and consumer markets expectations.

This study requires conception skills including mechanics and acoustics, which will be brought by LETI and LVA. This MEMS structure using nanowire detection will be coupled with a very low consumption electronics, which is a field of expertise of IM2NP. The project eventuelly includes a SME, Neurelec, a cochlear implant specialist, which will bring applicative prospects and will be deeply involved in specifications, signal processing and final demonstrator assessement.
The project has also strong support from Tronics, a MEMS manufacturer, which is not included in the project but will be consulted in the framework of valorization of the product, which is in its roadmap.

By realizing innovative microphone demonstrators, this ambitious project aims at demontrating the possibility of realization and the interest to use NEMS for high volume or medical applications and the possibility and the added value of co-integration of microphones and inertial sensors, which will be as far as we know a world first.