Post-doc offers

Context and subject: The research engineer position is proposed by the “Groupe de Physique des Matériaux”, GPM UMR 6634 CNRS lab, from the University of Rouen Normandy-CNRS, in the Microelectronics, Materials and Failure Research Team. The project is part of the Carnot ESP project "SiC-Ageing", the subject is the "Characterization of local electrical and mechanical modifications of the SiC chip after ageing (electrothermal ageing and irradiation)". It is being carried out in collaboration with the CRISMAT laboratory at the University of Caen. The impact of accelerated ageing, simulating the life of the component in its environment, will be determined thanks to the characterization of the local properties of the active parts, i.e. at the heart of the SiC material. Electrical characterization benches available at the GPM will enable the detection of ageing and failures by varying certain key parameters (static pulsed IV measurements, saturation current Idsat, on-state resistance Rdson, transconductance Gm, gate leakage current Igss, drain leakage current Idss, capacitance measurements CV.... ). SiC-ageing proposes to analyze the degradation and deterioration of the semiconductor by electrical techniques based on an Atomic Force Microscope (AFM), the experimental part concerning the AFM will be carried out in collaboration with a post-doc from the CRISMAT laboratory in Caen. For this purpose, fine preparations of the components in the package (front or back face) are essential and will be developed within the framework of this work. It will thus be possible and necessary to locate the defects within the component by de-packaging, laser ablation or chemical etching, then by PEM photoemission microscope or by OBIRCH (Optical Beam Induced Resistance Change) techniques.

Workplace : Rouen - Saint Etienne du Rouvray - Normandy - France - Groupe de physique des matériaux UMR CNRS 6634. Access to the GPM is regulated (ZRR: restricted areas) and recruitment is subject to the favourable opinion of a request for access.

Main scientific field : Physics

Secondary scientific fields: Electronics, Materials

Keywords: SiC MOSFET, ESD stress, electrical characterization, fault location, physical failure analysis.

Duration: 4 to 6 months, start of postdoc desired on 1 October 2024

Application deadline : 31/07/2024

Different missions :

To analyse and master the experimental means of electrical characterisation available at the GPM, implementation on sample components. Develop and apply sample preparation methods (de-pakaging, laser ablation, chemical etching, front and rear opening, etc.) on the study components. Implement measurements by PEM and OBIRCH photon emission microscopy to locate defects.

Interested candidates should send a CV, a cover letter to Pr. Pascal Dherbécourt: pascal.dherbecourt@univ-rouen.fr.

Spatially coherent sources of high-energy extreme-ultraviolet (EUV) photons and the tight focusing associated to the EUV beams are required for various scientific and industrial applications such as nanoscale imaging by atom probe tomography. The atom probe tomography (APT) is an advanced characterization method with very high spatial resolution that allows performing analytical imaging of materials in three dimensions at the atomic scale [Blavette1993, Gault2006]. Remarkable advances in the analysis of insulating materials were only achieved using UV laser pulses (around 340-400 nm) thanks to their high photon energy, thus paving the way for APT exploitation in new areas such as geophysics and biology. The use of EUV sources with photon energy up to 20 eV will allow the analysis of ultrawide band gap materials and will also improve the chemical composition measurements.

This project aims first to build a EUV photons source based on High Harmonic Generation (HHG) in large bandgap material (amorphous silica) using a long wavelength (mid-infrared) few-cycle (sub-30 fs) laser. Indeed, HHG in amorphous silica has already enabled the production of high photon flux at energies up to 25 eV [You2017].

The second objective will concern the coupling of the EUV source to an APT chamber to analyse wide band-gap materials in order to explore the evaporation process induced by such high energy photons and thus evaluate their potential for APT’ performances improvement [Vella2013].
The generation of EUV light in large band-gap materials and its application to APT are in the focus of the ANR project (Flex-UV) that will be conducted in collaboration between the GPM group (The University of Rouen, gpm.univ-rouen.fr, the laboratory LOA (École Polytechnique https://loa.ensta- paris.fr/the-laboratory/organization/) and the laboratory Xlim (The University of Limoges : https://www.xlim.fr/)

Post-doctoral position (starting from October/November 2022)

The work consists to develop an optical bench to generate EUV pulses starting from the post- compression of sub-picosecond pulses delivered by a fiber laser and their focusing on oxide materials. After characterization, the EUV light will be coupled to the Atom Probe Tomography chamber, assuring the focusing of EUV wavelengths on the nanometric sample.

The work will be aimed at the activation and optimization of the ATP results, such as time-of- flight spectra, and the study of photo-ionization process.
The successful candidate can be specialized in physics with particular knowledge in optics, non-linear optics and laser-matter interactions. Previous experience in laser development or high harmonic generation will be highly appreciated.

Contact : Pr Angela Vella
Groupe de Physique des Matériaux, 76801 SAINT ETIENNE DU ROUVRAY CEDEX FRANCE

E-mail: Angela.vella@univ-rouen.fr 

Phone: (33) (0)2 3295 5168

Institute: gpm.univ-rouen.fr

In the framework of a new project (Fusion SATMET), GPM has recently acquired a new STEM equipped with a time resolved direct detection camera, electron precession and advanced softwares allowing for orientation mapping. Preliminary work has allowed the design and fabrication of original TEM holders that allow to reproduce the condition of APT in STEM, i.e. application of a high voltage (DC + pulsing) to a sharp needle at cryogenic temperature. Beyond the coupling with APT detection in STEM, a main axis of the project is to take advantage of 4D STEM methodologies to extract a maximum of information such as: i) the electric field mapping in and around the polarised specimens; ii) evolution of electric field distribution during the sequence of field evaporation of specimens; iii) the mapping of crystal defects (e.g. grain boundaries, dislocations).

We are now seeking a post-doctoral fellow that will rapidly be able to produce original results that shall be published from the first year of the fellowship. Candidates must hold a PhD in materials sciences. A strong background in transmission electron microscopy is highly recommended. Skills in coding will be appreciated (e.g. python, MatLab, c++). Previous experience with atom probe tomography and/or specimen preparation in FIB SEM is not mandatory but might be considered interesting.

The duration of the post-doctoral fellowship is 1 year (+1 renewable year possible), starting autumn 2022 or earlier. This post-doctoral fellowship is granted by the European Union (ERDF) and Normandy Regional Council in the framework of RIN Tremplin Fusion SATMET.

Interested candidates should send a CV, a letter of motivation and the names of 2-3 references to williams.lefebvre@univ-rouen.fr