PhD Defense of Melissa ARABI

    The microelectronics industry has invaded our daily lives, particularly in the communication, automotive, medical and space industries applications. This great success was achieved thanks to the field effect transistor which is designed to dimensions of around ten nanometers. Nowadays, this race to miniaturization has created new challenges, as new industrial constraints linked to devices reliability, have been imposed and must not be neglected in order to ensure the proper functioning of the circuit. This loss of reliability is mainly linked to MOS transistor ageing due to oxide breakdown, temperature instabilities, hot carriers etc. As such, it has become necessary to investigate new approaches that can offer more lifetime gains for MOS transistors. It is in this context that this thesis work is set. Among the degradation modes of the transistor, the one that most limits its lifetime is gate oxide breakdown, or commonly called TDDB (Time Dependent Dielectric Breakdown). This is an irreversible breakdown of the dielectric. It corresponds to the loss of the insulating property of the gate oxide. It occurs when a conduction (or percolation) path between the gate and the channel is created by an accumulation of defects which leads to an increase in leakage current and makes the transistor breakdown.
    For this purpose, the investigation of new lines of research, allowing a significant margin on the lifetime with the analysis of the dynamic effects of gate breakdown, has been achieved. This study is therefore based on the experimental characterization of this degradation, particularly for the frequency aspects of dielectric breakdown, by proposing an extension of the study of breakdown in the high frequency range and by developing measurement methodologies adapted to this frequency range. We also propose an explanation for the AC/DC effects origin and a new approach to model the dielectric degradation mechanism over time in an AC and DC mode.

• Bruno ALLARD, Professor of Universities  INSA-Lyon : Reviewer
• Alain BRAVAIX, Professor of Universities  ISEN-Toulon : Reviewer
• Ahmad BSIESY, Professor of Universities  UGA-Grenoble: Examine, President
• Gérard GHIBAUDO, Director of  Research  CNRS:  Supervisor