PhD defense : Development of low-noise magnetic tunnel junctions for magnetic field sensors

On Thursday, the 22th Of June 2017 at 14h00, Myckael MOUCHEL from CROCUS TECHNOLOGY (DRF/INAC/SPINTEC), will defend his PhD thesis entitled “Development of low-noise magnetic tunnel junctions for magnetic field sensors”
Place : Amphithéâtre Grenoble INP-PHELMA – 3 parvis Louis Néel, Grenoble
Magnetic tunnel junctions based magnetic field sensors are one of the most promising solutions in the framework of electronic components miniaturization. Crocus Technology, the industrial stakeholder of this thesis, has been designing some of the market smallest TMR sensors for several years. Despite their good sensitivity, they exhibit a large 1/f noise, deteriorating their capability to detect low magnetic fields. This thesis falls within a context of noise reduction and detection improvement of the sensors. In-depth noise studies of existing sensors have been performed in order to better apprehend the origins of such noise. These studies have been carried out thanks to a specifically designed experimental bench allowing simultaneous noise and magneto-electrical characterizations of the devices. Thereby, we have been able to link the observed noise to the response of the sensors under specific magnetic field conditions by developing an illustrative model based on “magnetic-to-noise fingerprint of the sensors”. This thesis was further completed by a 6-sigma project, led by the author, which allowed us to implement the needful solutions to answer an ambitious objective of noise reduction. The detectivity has been improved by nearly two orders of magnitude, thus reaching 13 nT/√Hz at 10 Hz in a few months, without deteriorating the integrability of the sensors while satisfying industrial constraints.

Jury :
Michel HEHN, Institut Jean Lamour
Laurent RANNO, CNRS-Institut Néel

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