Introduction of innovative materials for sub-10nm contact realization
As part of the FAMES project and the European ChipACT initiative, which aim to ensure France’s and Europe’s sovereignty and competitiveness in the field of electronic nano-components, CEA-LETI has launched the design of new FD-SOI chips. Among the various modules being developed, the fabrication of electrical contacts is one of the most critical modules in the success of advanced node development.
For sub-10 nm node, the contact realization is facing a lot of challenges like punchthrough (due to low etch selectivity during contact etching), voids during metal deposition, self-alignment, and parasitic capacitance. New breakthrough approach has recently been proposed consisting in the deposition of new dielectric films with chemical gradient. This thesis focuses on the development (deposition an etching processes) of new gradient compounds incorporated into SiO2 to address the current issues.
Effect of gamma-ray irradiation on ferroelectric, hafnia-based, non-volatile memory for use in extreme environments
The emergence of hafnia-based ferroelectric (FE) memories has opened a new paradigm for ultra-low-power edge computing. Hafnia is fully compatible with CMOS technology and is ultra low-power—three orders of magnitude less than other emerging memory technologies.
These advantages align with strategic applications in space, defense, medical, nuclear safety, and heavy-duty transport, where electronics face harsh radiation environments.
Imprint induces a shift of the Polarization-Voltage (P-V) curve along the voltage axis and is attributed to charge trapping/detrapping, domain pinning and charged defects. All may be accentuated under irradiation.
The project will use advanced photoelectron spectroscopy techniques including synchrotron radiation induced Hard X-ray photoelectron spectroscopy and complementary structural analysis including high-resolution electron microscopy, X-ray diffraction and near field microscopy. The experimental characterization will be accompanied by theoretical calculations to simulate the material response to irradiation
The work will be carried out in the framework of close collaboration between the CEA/Leti in Grenoble providing the samples, integrated devices and wafer scale characterization and the CEA/Iramis in Saclay for the fundamental analysis of the material properties, irradiation experiments and device scale characterizations.
Investigation and Modeling of Ferroelectric and Antiferroelectric Domain Dynamics in HfO2-Based Capacitors
The proposed PhD work lies within the exploration of new supercapacitor and hybrid energy storage technologies, aiming to combine miniaturization, high power density, and CMOS process compatibility. The hosting laboratory (LTEI/DCOS/LCRE) has recognized expertise in thin-film integration and dielectric material engineering, offering unique opportunities to investigate ferroelectric (FE) and antiferroelectric (AFE) behaviors in doped hafnium oxide (HfO2).
The thesis will focus on the experimental investigation and physical modeling of thin-film HfO2-based capacitors, intentionally doped to exhibit ferroelectric or antiferroelectric properties depending on the composition and deposition conditions (for instance, through ZrO2 or SiO2 doping). Such materials are particularly attractive for realizing devices that combine non-volatile memory and energy storage functions on a single CMOS-compatible platform, enabling ultra-low-power autonomous systems such as edge computing architectures, environmental sensors, and smart connected objects.
The research will involve the fabrication and characterization of metal–insulator–metal (MIM) capacitors based on doped HfO2 integrated on silicon substrates. Systematic electrical measurements—including current–voltage (I–V) and polarization–electric field (P–E) characterizations—will be carried out under various frequencies, amplitudes, and cycling conditions to investigate the relaxation mechanisms of FE and AFE domains. Analysis of minor hysteresis loops will provide access to the distribution of activation energies and enable the modeling of domain relaxation dynamics. A physical model will be developed or refined to describe FE/AFE transitions under cyclic electrical excitation, incorporating effects such as charge trapping, mechanical stress, and domain nucleation kinetics.
The overall objective is to optimize the recoverable energy density and the energy conversion efficiency of these capacitors, while establishing design guidelines for compact, efficient, and silicon-integrable energy storage devices. The insights gained from this work will contribute to a deeper understanding of the dynamic mechanisms governing FE/AFE behavior in doped HfO2, with potential impact on ferroelectric memories, energy-harvesting devices, and low-power neuromorphic architectures.
Advanced electrode materials by ALD for ionic devices
This work aims to develop Advanced ultrathin cunductive layers (<10nm) by ALD (Atomic Layer Deposition)for électrodes use(resistivity 100). The other challenge aims to reduce the ALD-based electrode layer thickness less than 5nm while still maintaining the advanced electric properties (resistivity in the mOhm range).
This work covers multiple aspects including inter alia ALD process, ALD precursors, Elementary characterization of intrinsec properties (physico-chemical, morphological and electrochemical) as well as integration on short loop 3D devices.
Fabrication of Metasurfaces by Self-Assembly of Block Copolymers
Block copolymers (BCP) are an industrial technology in full expansion, offering promising perspectives for material nanostructuring. These polymers, composed of chemically distinct block chains, self-assemble to form ordered structures at the nanometric scale. However, their current use is limited to specific nanostructuring per product (1 product = 1 nanostructuring), thus restricting their application potential.
This PhD proposes to develop an innovative method to create multiple patterns in a single BCP self-assembly step using a mixture of two products. The student will also focus on controlling the localization of these patterns using chemoepitaxy, a technique combining chemical and morphological guidance to precisely control the position of patterns at the micrometric and nanometric scales.
The work will proceed in several steps: understanding the mechanisms of mixed block copolymers, developing functionalized substrates for chemoepitaxy using advanced lithography techniques, and conducting BCP self-assembly experiments on these substrates. The resulting structures will be analyzed using the metrology equipment available at CEA-Leti.
The targeted applications include the creation of nanostructures capable of interacting with light, reducing diffraction, and controlling polarization. The expected results include demonstrating the ability to generate multiple types of patterns in a single self-assembly step, with precise control over their position and dimensions.
Superconducting silicide contacts on hyperdoped silicon by nanosecond pulsed-laser annealing
In the race towards building a quantum computer, there is a deep interest in fabricating devices based on the robust and scalable silicon FD-SOI technology. One example is the Josephson Field Effect Transistor (JoFET) whose operability relies on the high transparency of the interface between the superconducting source/drain regions and the semiconducting channel. Such transparency could be improved by doping the source/drain regions, and hence lowering the Schottky barrier height at the superconductor/semiconductor interfaces.
This PhD aims at developing highly transparent superconducting silicide contacts on a 300 mm production line using Nanosecond Pulsed Laser Annealing (NPLA). NPLA will play a key role for reaching extremely high doping concentrations in silicon [1,2], then forming the superconducting silicides (CoSi2, V3Si) with minimal thermal budget and related dopant deactivation. A particular focus will be devoted on the stresses during silicide formation and their impact on the superconducting critical temperature. Also, the distribution of dopants will be assessed by Atom Probe Tomography (APT), an advanced 3D imaging technique capable of imaging the distribution of dopants at the atomic scale [3]. Finally, electrical measurements on fabricated junctions and transistors will be carried out at low temperature (< 1 K) in order to evaluate the transparency of the superconducting contacts.
III-V semiconductor nanoplatelets
Colloidal semiconductor nanoplatelets (NPLs) are a class of two-dimensional nanostructures that have electronic and optical properties distinct from those of spherical quantum dots (QDs). They exhibit strong quantum confinement in a single dimension, their thickness, which can be controlled on the monolayer level using solution chemistry. As a result, NPLs emit light with an extremely narrow spectral width and at the same time, they have a very high absorption coefficients. These properties make them ideal candidates for various applications (e.g., light-emitting diodes for low-power-consumption displays, photocatalysis, single-photon emitters).
At present, only the synthesis of metal chalcogenide NPLs has been mastered. These materials either contain toxic elements (CdSe, HgTe, etc.) or have a large bandgap (ZnS, ZnSe). For these reasons, the development of synthesis methods for III-V semiconductor NPLs, such as InP, InAs and InSb is currently a major challenge. In this thesis, we will develop new synthetic approaches for the growth of InP NPLs, exploring different avenues and using in situ characterizations as well as machine learning assisted design of experiments. Numerical simulations will be used to determine the reactivity of precursors and to model the mechanisms inducing anisotropic growth.
New generation of organic susbtrates for power conversion
Recent advances in electric motors and associated power electronics have led to a significant increase in power density requirements. This increase in power density means smaller heat exchange surfaces, which amplifies the challenges associated with dissipating the heat generated by power electronics components during operation. In fact, the lack of adequate heat dissipation causes electronic components to overheat, impacting their performance, durability, and reliability. Other issues related to cost, repairability, and thermomechanical constraints call into question traditional ceramic-based insulating thermal interfaces. It is therefore imperative to develop a new generation of heat-dissipating materials that take the system environment into account.
The objective of this thesis is to replace the ceramic substrate in power module systems, whose main role is to act as the system's dielectric layer, with a thermally conductive organic matrix composite. The current substrate has well-known limitations (fragility, poor interface, cycling limit, cost). The organic substrate must have the highest possible thermal conductivity (>3 W/m.k) in order to dissipate the heat emitted properly, while also being electrically insulating with a breakdown voltage of approximately 3kV/mm. It must also have a coefficient of thermal expansion (CTE) compatible with that of copper in order to eliminate delamination phenomena during the cycling undergone by the device during its lifetime. The innovation of the doctoral student's work will lie in the use of highly thermally conductive (nano)fillers that will be electrically insulated (insulating coating) and can be oriented in a polymer resin under external stimulus.
The development of the electrical insulating shell on the thermally conductive core will be carried out using the sol-gel method. The synthesis will be controlled and optimized in order to correlate the homogeneity and thickness of the coating with the dielectric and thermal performance of the (nano)composite. The charge/matrix interface (a potential source of phonon diffraction) will also be studied. A second part will focus on grafting magnetic nanoparticles (MNPs) onto thermally conductive (nano)fillers. Commercial MNPs will be evaluated (depending on requirements, grades synthesized in the laboratory may also be evaluated). The (nano)composites must have rheology compatible with pressing and/or injection processes.