Reliability of the copper (Cu) direct bonding interconnects for 3D integration
Copper direct bonding is one of the most promising approaches for 3-D integration. The process is mature as shown in the literrature for wafer to wafer (W2W) approach [1-3] but also in the case of a die to wafer one (D2W). However, its reliability is yet to be demonstrated even if the initial results from the PhD thesis of R. Taibi seem to be promising [4].
The purpose of this post-doc position will be first, to consolidate the results obtained by R. Taibi with the W2W approach and secondly, to study the reliability of the D2W approach from the electromigration and stress-induced voiding point of view.
The candidate will be responsible for all the reliability study, starting with the tests and the results’ analysis, failure analysis (optical, IR, SEM, FIB...), the determination of the degradation’s mechanisms.
1. Gueguen, P., et al. Copper direct bonding for 3D integration. in Interconnect Technology Conference, 2008. IITC 2008. International. 2008.
2. Taibi, R., et al. Full characterization of Cu/Cu direct bonding for 3D integration. in Electronic Components and Technology Conference (ECTC), 2010 Proceedings 60th. 2010.
3. Di Cioccio, L., et al., An Overview of Patterned Metal/Dielectric Surface Bonding: Mechanism, Alignment and Characterization. Journal of The Electrochemical Society, 2011. 158(6): p. 81-86.
4. Taibi, R., et al., Investigation of Stress Induced Voiding and Electromigration Phenomena on Direct Copper Bonding Interconnects for 3D Integration, in 2011 IEEE International Electron Devices Meeting (IEDM). 2011: Washington, DC.
Electrical Study of Conductive Bridge Random access Memory (CBRAM)
CBRAM memories are among the most promising technologies as alternative to Flash technologies which face strong problems of scaling. CBRAM have a capacitor-like stack, where a chalcogenide material is sandwiched between a silver anode and an inert cathode. Biasing the cell, silver ions diffuse in the chalcogenide matrix and reach the cathode where they reduce. A conductive bridge is formed between the electrodes causing a drop of resistance. Reversing the bias yields to a back-migration of silver, interrupting the conductive bridge. This kind of device can be operated at very low voltage (below 1 V) and can lead to extremely low power consumption.
The main objective of this postdoc position will be the electrical characterization aiming to a better comprehension of the physics involved in the device, with the final goal of a strong improvement in device characteristics, in particular concerning data retention. For this aim, in-depth characterization on particular features (i.e. conduction mode, failure mechanisms) will be performed, as much as possible linked to a first level of physical modelling linking current conduction and diffused ions in the matrix. The candidate will address both hardware & methodology issues, and particular attention will be devoted to pulsed measurements. Various process, geometries and architectures will be studied. A strong interaction with the specialists of materials characterizations (nano-characterization platform) will be promoted for a better physical knowledge of the structures.
Development and application of TERS/TEPL technique for advanced characterization of materials
TERS/TEPL (Tip-Enhanced Raman Spectroscopy and Tip-Enhanced Photoluminescence) are powerful analytical techniques developed for nanoscale material characterization. The recent acquisition of a unique and versatile TERS/TEPL equipment at PFNC (Nano-characterization Platform) of CEA LETI opens up new horizons for materials characterization. This tool combines Raman spectroscopy, photoluminescence, and scanning probe microscopy. It features multi-wavelength capabilities (from UV to NIR), allowing a wide range of applications and providing unparalleled insights into the composition, structure, and mechanical/electrical properties of materials at nanoscale resolution. The current project aims to develop and accelerate the implementation of the TERS/TEPL techniques at PFNC to fully exploit its potential in diverse ongoing projects at CEA-Grenoble (LETI/LITEN/IRIG) and with its partners.
Immunotargeting of based-organic nanoparticles for clinical applications
The project aims to tailor-make based-organic nanocarrier enabling to target antibodies to increase the efficacy of therapy (more particularly mantle cell lymphoma) for clinical applications. Our group has developed a unique delivery system based on lipid nanoparticles for imaging and therapeutic purposes since the last 6 years. Based on this technology, the candidate will:
- optimize the targeting of specific ligands into organic nanoparticles (bioconjugate chemistry)
- optimize the encapsulation of drugs in the immunotargeted nanoparticles
- assess the physico-chemical characterization of all nanoparticles
- evaluate the binding affinity of doped and targeted nanoparticles
Droplets motion through modulation of surface energy gradient
Droplet motion through electro-wetting is nowadays largely studied and used in several systems and applications. In order to be useful, this technique needs an electrical field to monitor the droplet. For this post-doctoral fellowship, the main objective is to define an alternative method to the using of the electro-wetting technique in order to generate a droplet motion. The elaboration of surfaces with energy gradients conceived by thin film deposition or by laser ablation will be realized inside this study. The main difficulty is related to the patterns realization in order to obtain the appropriate hydrophilic/hydrophobic resolution. Apart from these “classical” techniques, an innovative method will be studied here by using switchable molecules. These molecules could modify the contact angle between a surface and a droplet, when acting on the potential of hydrogen (pH) or the wall temperature. For all the defined surfaces, the post-doctoral fellow will also analyze the coupling effect between the surface energy gradient and a thermal energy gradient on the droplet motion dynamics.
Batteries recycling :Development and understanding of a new deactivation concept of lithium ion domestic batteries
Domestic lithium ion batteries gather all batteries used in electronic devices, mobile phone, and tooling applications. By 2030, the domestic lithium-ion battery market will increase up to 30%. With the new European recycling regulation and the emergency to find greener and safer recycling process, it is today necessary to develop new deactivation process of domestic lithium ion batteries.
The process has to address several lithium ion chemistries, be continuous, safe, controllable and low cost.
To develop this new concept, the first step will be to define the most appropriate chemical systems. Then these chemical systems will be tested in a dedicated experimental laboratory setup using chemistry and electrochemistry, allowing the simulation of real conditions of domestic batteries deactivation.
The third step will be to characterize, understand and validate the electrochemical and physico chemical mechanisms. The last step will be to participate to the validation of the deactivation concept on a real object (a lap top battery) in representative conditions (on the abuse tests plateform of CEA).
Unsupervised Few-Shot Detection of Signal Anomalies
Our laboratory, located at Digiteo in CEA Saclay, is looking for a postdoc candidate working on the subject of anomaly detection in manufacturing processes, for a duration of 18 months starting from Feburary 2022. This postdoc is part of HIASCI (Hybridation des IA et de la Simulation pour le Contrôle Industriel), a CEA LIST project in an internal collaboration which aims at building a platform of AI methods and tools for manufacturing applications, ranging from quality control to process monitoring. Our laboratory contributes to HIASCI by developping efficient methods of anomaly detection in acoustic or vibrational signals, operating with small amounts of training data. In this context, the detection of signal anomalies (DSA) consists of extracting from data the information about the physical process of manufacturing, which is in general too complex to be fully understood. Moreover, real data of abnormal states are relatively scarce and often expensive to collect. For these reasons we privilege a data-driven approach under the framework of Few-Shot Learning (FSL).
Lensfree Cytometry for High-troughput biological analysis
The new lensfree imaging is against the foot of the recent developments in microscopy that focuses today on super-resolution achievements. Instead lensfree imaging offers several advantages: field of view (FOV) can cover several cm2, resolution in the range of 0.5µm to 3µm, mostly compact sizes and ease of use. The technique is based on holography online as invented by Gabor [1]. A biological object is illuminated by a coherent light, micrometric structures of the object diffract and the light interferes with the incident wave. The amplitude of the interference is recorded by a CMOS sensor and the image is reconstructed thanks to inverse-problem approaches. Albeit the method exists since 1970, the recent development of large field, small pixel size digital sensors helped realize the full potential of this method only since 2010.
At CEA-LETI Health Division, a new microscopic platform based on this principle has been developed. Its applicability for performing high-throughput monitoring of major cell functions such as cell-substrate adhesion, cell spreading, cell division, cell division orientation, cell migration, cell differentiation, and cell death have been demonstrated [2,3]. The new project proposed in this PostDoc is dealing with the development of an innovative lensfree cytometry setup aiming at high-throughput analysis of biological samples, e.g. cell counting, cell sorting, etc. The post-doctoral fellow will develop the instrumentation and methods and will conduct the experimentation and analysis of true biological samples.
Simultaneous Localisation and Mapping with an RGB-D camera based on a direct and sparse method
Recent advances in the methods of locating a device (smartphone, robot) in relation
to its environment make it possible to consider the deployment of augmented reality solutions and autonomous robots. The interest of RGB-D cameras in such a context is notable since it allows to directly acquire the depth map of the perceived scene.
The objective of this post docorate consists in developping a new SLAM (Simultaneous Localisation and Mapping) method relying on a depth sensor.
To reach a solution both robust, accurate and with small CPU/memory comsumption, the depth image will be exploited though a direct and sparse approach. The resulting solution will be then combined with the solution of "RGB SLAM Constrained to a CAD model" developped in our laboratory, resulting finaly in an "RGB-D SLAM Constrained to a CAD model"
Study of the thermo-mechanical strains in the HEMT AlGaN/GaN on silicon
Fabricating the HEMT AlGaN/GaN device is complex and leads to the formation of crystalline defects. These strains, in the GaN layer, leads to crackings in the GaN layer or leads to a delamination at the top interface. Moreover, these mechanical strains conjugated to thermal strains during device working, can lead to a degradation of the electrical performance of the device.
This heterogeneous assembly, involve a complex behaviour. The various materials used, react differently to the thermal-mechanical strains. The requested work is to study and to model the distortion of this structure, in order to evaluate the strains effects on the electrical performance on lateral and vertical devices.