Selective removal of metal alloy for advanced silicidation applied to sub-20nm CMOS transistors
CMOS transistor performances depend on electrical contact resistivity reduction. Thus, self aligned silicidation (salicide) is one of the key processes which have to be improved to meet the ITRS requirements for the future technological nodes. Nowadays, solid state reaction between thin metal layer (Ni1-yPty < 10nm) and a silicon substrate allows to decrease access resistances of transistor source & drain. The metal is currently deposited by physical vapor deposition method all over the wafer surface. Under heat treatment, metal reacts preferably with semiconductor areas rather than dielectrics ones. Then, unreacted metal layer is selectively etched with an appropriate acidic solution; only metal silicide remains.As new specifications (use of ultra-thin Ni-alloy,very low temperature process leading to partial salicidation, use of various additive metals ...)are required for advanced nodes (C20nm & C14nm), the capability to chemically remove the excess of metal on dielectric areas has to be investigated. In the clean room environment of CEA-LETI (Grenoble, France), the candidate will work on innovative wet chemistries to remove selectively the different metallic layers (Ni, Pd, NiCo, NiPd…). In a first time preliminary test will be conducted on sample in manual tank in order to check removal kinetic and global selectivity on structures devices… Based on several characterization techniques (TXRF, XRR, AFM, SEM, TEM, XRD…), residual additive interaction with dielectric and chemical mixture behavior towards the metal rich phase on silicided area (roughness, resistivity) will be studied. Different semi-conductor (Si, SiGe…) and dielectrics surfaces (SiO2, SixNy…) will be investigated. Afterwards the most promising selective processes will be selected to be installed on a fully automatic 300mm tool. Finally, best processes will be integrated on critical patterned wafer architectures for morphological and electrical characterizations.
Design of integrated photonics modules
Design of next generation optoelectronic transceivers (particularly on-board modules) requires the merging of two advanced technologies: Silicon Photonics and 3D Silicon Packaging, both being developed at Leti.
In order to meet the requirements in term of technical specifications, cost and density, it is needed to achieve a codesign involving mechanical, thermal, optical and mainly RF aspects.
The aim of the work consists in designing such integrated modules by optimizing the RF interconnections of the module (internal and external), and the proper setup of the integrated circuits (ASICs). Modelling of several architectures will be led under HFSS and ADS softwares.
Finally, the integration of the module into its system environnement will be taken in charge, so as its characterization (involving testboard and testbench design).
Real time low cost algorithms for brain computer interface with multiple degrees of freedom
The topic of the postdoctoral project is the optimization of BCI methods and algorithms for medical application in humans (quadriplegic subjects).
Namely the particular goal of the postdoctoral fellow will be optimization and the acceleration of calculation to allow multiple degrees of freedom (up to 26) in real time. Selecting the appropriate features subset will improve the computational efficiency and the quality of control. To this purpose the algorithms of sparse modeling will be applied.
To map ECoG recordings to the spatial-temporal-frequency space, continuous wavelet transform (CWT) is applied. Optimization will include the implementation of low cost CWT and C++ coding.
The project will include the test and the adaptation of BCI algorithms to wireless signal transmission with the implant WIMAGINE.
Finally the adaptation of algorithms to medical environment of quadriplegic subjects (the use of imaginary tasks, presence of stimuli in the signal, the restricted duration of experiments) will be under responsibility of postdoctoral scientist.
3D sequential integration
3D integration is currently under great investigation because it offers a solution to keep increasing transistor density while relaxing the constraint on the transistor’s dimension and it eases the co integration of highly heterogeneous technologies compared to a planar scheme.
3D sequential integration offers the possibility of using the third-dimension potential: two stacked layers can be connected at the transistor scale. This contrasts with 3D parallel integration, which is limited to connecting blocks of a few thousand transistors. However, its implementation faces the challenge of being able to process a high performance top transistor at low temperature in order to preserve the bottom FET from any degradation, as the stacked FETs are fabricated sequentially.
Nonlinear dynamic analysis of a reinforced concrete structure subjected to seismic loadings: Deterministic and probabilistic study of response spectra
The proposed work is based on the experimental campaign of the ENISTAT project and is composed of three parts:
1. Calibration and enhancement of the numerical model (5 months)
Based on the nonlinear numerical model that has been realized in CEA, the applicant will have to compare the results to those provided by the experimental campaign. The potential gaps will be interpreted and the model should be calibrated (and/or enhanced) to ensure a satisfactory accordance with the experimental results and observations.
2. Deterministic and probabilistic analysis of response spectra (5 months)
Based of the numerical model that will have been calibrated, the response spectra will be computed in given points. They will be compared the demand spectra prescribed by the design rules such as the EC8. Based on probabilistic methods that are developed in CEA for seismic applications, the uncertainties not only of the input parameters but also of the seismic signals will be taken into account. The induced variability of the response spectra will be quantified and discussed. One can notice that the knowledge of these data is particularly interesting since design rules in seismic engineering are based on them.
3. Study of the effect of the thermic brick elements
Thanks to the experimental results, not only experimental but also numerical, a discussion on the effect of the thermic brick elements will be realized with the aim to draw first conclusions on their effect on the overall structural behavior under seismic loading.
Development of a Metal Supported Cell for Hydrogen production by High Temperature Steam Electrolysis
The development of Metal Supported Cells (MSC) for High Temperature Steam Electrolysis (HTSE) constitutes an interesting innovation able to reduce the degradation of this component under operation. An increase in the cell life time would be a valuable contribution to cost reduction and is able at positioning HTSE as an alternative process to other hydrogen production technologies. However, some progresses in the elaboration of MSCs are still required. Within the current process, functional ceramic layers of the MSC are joined to the metallic substrate at elevated temperature (> 1000 °C). Mismatch of the mechanical properties of the materials as well as the reducing conditions fixed by the metal substrate during sintering lead to MSCs having insufficient electrochemical performances. The post-doctorate aims, on the one hand, at obtaining a better understanding of the mechanisms that occur in the multilayer structure during sintering and, on the other hand, at proposing and testing technological solutions able to improve to reliability of MSC elaboration.
Development of numerical tools for the simulation of ultrasonic nondestructive inspection.
The CEA LIST develops the CIVA software platform (http://www-civa.cea.fr), in position of global leader for the simulation and expertise of non-destructive testing (ultrasonic and electromagnetic methods, radiography, X tomography). In the context of extending and improving capabilities of the CIVA platform, the post-doc fellow will contribute to the development of numerical methods for the ultrasonic testing (UT) simulation module.
The semi-analytical models of CIVA are based on physical simplifying hypotheses for the propagation of the ultrasonic beam and its interaction with defects. These methods provide efficient computational performances with accurate results in a wide range of realistic applications. However, configurations for which these models are not valid. The so called “numerical models” including finite element method (FEM), finite difference method (FDM) or boundary element method (BEM) enable to deal with these configurations without any simplifying hypotheses. However, the computation time is prohibitive in an industrial context, especially for 3D applications. The approach adopted in the CIVA platform consists in hybridizing semi analytical models with numerical ones in order to benefit of both the numerical efficiency of the former and the capability of simulating complex phenomena of the later.
The tasks associated to the post include the development of numerical methods themselves, in collaboration with academic partners, the integration in CIVA of a meshing solution enabling the data formatting for the numerical solving and specific developments for the coupling with semi analytical methods. Multi-boxes solutions, enabling for example the optimization of configurations with several defects or a coupling around the source and the defect, will be studied.
Reverse engineering of an internal permanent magnet synchronous electrical machine and modelisation of evolutions based on new new magnet technologies developped in CEA
The study aims at studying and modeling a synchronous electric motor with magnet buried in the rotor. This study begins with a preliminary phase of retro engineering and modeling of an existing machine. A second phase will focus on the design and the modeling of a new machine integrating a new technology of magnets developed in the CEA.
In the context of electric transportation, if batteries and energy storage are still the weak point of the energy chain, the electric motor remains a central part that has to be optimized to raise efficiency. For twenty years, all motor structures have been studied and tested: dc motors, synchronous machines with permanent magnets, asynchronous machines and switched reluctance machines. This study will focus on a synchronous machine with magnets buried into the rotor. This type of machine offers a natural ability of delivering at full load a constant power along a wide speed range, associated with a high efficiency. Moreover, power density can be improved by increasing maximal speed range.
The Post doc will be split into three parts:
1st phase:
Testing of an existing commercial electrical synchronous machine with magnets buried in the rotor and characterization of its components. These tests will be done on a motor test bench situated in the CEA
2nd phase:
Modeling of the commercial machine tested on the test bench and comparison of modeling results with experimental measurements from the first phase.
3rd phase:
Design and modeling of evolution of the machine tested and modeled in phases 1 and 2, integrating new technologies of magnets developped by the CEA.
Modelling of actinide electrorefining
Modelling of an actinide electrorefining process
In the frame of the SACSESS European project CEA, ITU and CNRS are studying jointly a pyrochemical process for the reprocessing of spent nuclear fuels by electrolysis in molten chloride salts.
The main objective of the proposed post-doctoral work concerns the modelling of electrorefining runs onto aluminium cathodes using U-Pu-Zr-Am-Gd-Nd-Ce-Y metallic alloy. The modelling aims to evaluate the efficiency of this electrolytic process in terms of separation factors and to optimize the process flow sheets for a safe nuclear materials management.
Compensation methods (for magnetic perturbation) for shape capture via orientation sensors
Our laboratory works for several years on shape capture (curves, surfaces) in static and moving positions, via inertial sensors - e.g. accelerometers ans magnetometers - able to provide information about their own orientation. In fact, in real conditions, sensors do not exactly provide their orientation, the measure is disturbed with external contributions (own motion acceleration, vibrations, magnetic perturbations). This work consists in analysing these disturbances, proposing preprocessing to clean data to obtain "denoised" tangential information to allow the reconstruction of these curves and surfaces.
First, we study the case of the reconstruction of a metallic pipe: we want to reconstruct a curve with magnetic sensors disturbed (the surface reconstruction will be explored afterwards). This work consists in finding the best methods allowing to extract the needed information from these "noised" signals (data fusion, source separation, model of perturbations, adding a new sensor modality,... are domains to explore). In this goal, a bibliographic study will be done firstly by the Post Doc student, then he will have to implement the different methods found, and test the performances with real signals acquired with our system of shape capture in a disturbed environment.