Plasma Etching development for the advanced nodes using SADP techniques
The miniaturization of the electronics components involves the development of new processes. Indeed, the 193nm immersion lithography alone does not permit anymore to achieve the dimensional requirements of the most advanced technological nodes (=10nm). Since the last 10 years, multi-patterning techniques have been developed to overcome the i193nm lithography limitations. Herein, we will study the « Self-Aligned Double Patterning » (SADP) technique that divides by two the initial pitch of the lithographical patterns. This technology relies on a conformal deposition of a dielectric film (spacer) over the initial patterns (mandrel). The spacers will be then used as a mask during the pattern transfer by plasma etching. The small targeted dimensions require a perfect control of the etching processes. However, the etching steps can damage the materials used herein leading to a dimension loss. One of the main challenge will be to control the etching steps and so the plasma-induced modification in order to satisfy the specifications (dimension, profile, material consumption, etch rate, uniformity…). Besides, the goal will be also to propose new SADP approaches allowing us to generate different type of patterns in order to produce planar FDSOI transistors, which is currently little reported in literature.
The challenges of this PhD ?
To develop innovative etching processes
To explore new couple of material (spacer/mandrel) and to propose an industrial integration flow that will be validated by electrical tests
To identify the technological obstacles and to propose solutions for overcoming them
To put in place a reliable characterization protocol in order to detect the physical and chemical modifications of the materials used and to accurately measure the final patterns’ dimensions
Sperm 3D - Male infertility diagnostic tool using holography for imaging and 3D tracking
Infertility is a growing problem in all developed countries. The standard methods for the diagnostic of male infertility examine the concentration, motility and morphological anomalies of individual sperm cells. However, one in five male infertility cases remain unexplained with the standard diagnostic tools.
In this thesis, we will explore the possibility to determine the male infertility causes from the detailed analysis of 3D trajectories and morphology of sperms swimming freely in the environment mimicking the conditions in the female reproductive tract. For this challenging task, we will develop a dedicated microscope based on holography for fast imaging and tracking of individual sperm cells. Along with classical numerical methods, we will use up-to date artificial intelligence algorithms for improving the imaging quality as well as for analysis of multi-dimensional data.
Throughout the project we will closely collaborate with medical research institute (CHU/IAB) specialized in Assisted Reproductive Technologies (ART). We will be examining real patient samples in order to develop a new tool for male infertility diagnosis.
Impact of plasma activation on reliability of Cu/SiO2 hybrid bonding integrations
In recent years, CEA-LETI emerged as a leading force in the development of advanced microelectronic manufacturing processes. A key focus has been on wafer-to-wafer Cu/SiO2 hybrid bonding (HB) process, an emerging technology increasingly employed for producing compact, high performance and multifunctional devices. Before bonding, a crucial surface activation step is necessary to enhance the mechanical strength of the assembled structures. Different approaches have been developed, and the most used in the industry is N2-plasma activation. However, this process remains controversial due to undesirable effects, the formation of Cu nodules at the bonding interface between particularly electrical pads and the passivation of Cu pads with chemical complexes. These issues can significantly compromise the electric properties and reliability of devices. In collaboration with STMicroelectronics and IM2NP, this PhD aims at studying the impact of plasma activation on Cu/SiO2 HB integrations.
Ultra-wide-field smart microscope for the detection of egg parasite (SCREENER)
In most parasitic cycles, the free phase passes through an egg stage, which is released by the host into the environment via a complex faecal matrix, which has highly variable and often low egg concentrations. The classical detection method relies on microscopic observation of these eggs, which implies a tedious and time-consuming preparation of the sample to concentrate the eggs, with highly variable sensitivity values. This detection is crucial because, once dispersed, the eggs contaminate the environment and food, leading to cases of parasitic zoonoses in humans.
Detection in environmental and food matrices is even more complex than for faeces because of the very low number of eggs present : 1 to 10 per sample in the vast majority of cases. The thesis aims at developing a lensless wide-field imaging system that will allow the counting and identification of parasite eggs in complex matrices, while increasing sensitivity. This will make it possible to automate detection, thus opening up the possibility of investigating more samples for better health surveillance.
Fracture dynamics in crystalline layer transfer technology
Smart Cut™ is a technology discovered at CEA and now industrially used for the manufacture of advanced substrates for electronics. However, the physical phenomena involved are still the focus of numerous studies at CEA. In Smart Cut™, a thin material layer is transferred from one wafer to another using a key fracture annealing step upon which a macroscopic fracture initiate & propagates at several km/s [i].
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Improving technology requires a solid understanding of the physical phenomena involved in the fracture step. The aim of this PhD project is thus to address the mechanisms involved in fracture initiation, propagation and post-fracture vibrations
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On the CEA-Grenoble site, with industrial interest, the student will use and further develop existing experimental setups to investigate the fracture behavior in brittle materials, including optical laser reflections [iv], time-resolved synchrotron diffracting imaging [iii], and ultra-fast direct imaging [ii].
In addition, python-based data analysis algorithms will be developed to extract quantitative information from the different datasets. This will enable the student to determine involved mechanisms and evaluate the influence of the wafer processing parameters on the fracture behavior, and thus propose improvement methods.
References :
[i] https://pubs.aip.org/aip/apl/article/107/9/092102/594044
[ii] https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.15.024068
[ii] https://journals.iucr.org/j/issues/2022/04/00/vb5040/index.html
[iv] https://pubs.aip.org/aip/jap/article/129/18/185103/158396
Microwave Near Field Sensing in Heterogeneous Media
This thesis focuses on the development of microwave near-field sensing techniques for applications in biomedicine, agronomy, and geophysics. The primary objective is to design low-complexity algorithms that effectively solve complex inverse problems related to the characterization and detection of dielectric properties with various geometric distributions in heterogeneous media.
The candidate will begin by conducting a comprehensive review of existing radar-based and advanced signal processing methods. A precise physical model of microwave propagation in near-field conditions will be developed, serving as the foundation for new detection methods based on the concept of physics-driven iterative tomography. The ultimate goal is to formulate efficient algorithms suitable for real-time applications and validate them through experimental implementation. To achieve this, an evolving prototype setup will be developed, progressing from 2D media to more complex 3D scenarios.
This interdisciplinary project combines physical modeling, algorithm development, and practical experimentation. It presents an opportunity to advance the field of microwave imaging, with significant implications for biomedical and environmental applications.
High-isolation power supply
With the rapid evolution of technologies and the growing challenges of miniaturization and resource management, power converters are facing ever more stringent performance requirements. To meet these needs, the use of wide-bandgap semiconductors such as SiC (silicon carbide) and GaN (gallium nitride) is becoming increasingly common. These materials significantly increase the switching speed of converters, reducing losses and improving efficiency.
However, this switching speed brings additional challenges: the steepness of the switching edges can cause stray currents that interfere with switch controls. To counter these undesirable effects, it is necessary to use switch drivers offering a high level of insulation. The traditional solution is based on high-frequency magnetic transformers, but these devices are expensive, take up a lot of space and offer limited insulation.
Thesis objective: the aim of this thesis is to design a new solution for powering wide-gap component drivers, by replacing magnetic transformers with piezoelectric transformers. This innovative approach aims to reduce costs, space requirements and improve the overall efficiency of power conversion systems.
Supervision and ressources: the selected candidate will work as part of a leading-edge research team, renowned for its expertise in the field of power conversion using piezoelectric resonators. The team has the resources and know-how to support the development and validation of this innovative technology.
Identification versus anonymisation from an embedded client operating on a blockchain
The first worldwide deployment of a blockchain dates back to 2010 with Bitcoin, which introduced a completely digital monetary system and a crypto-currency, bitcoin. Within Bitcoin, all transactions are publicly accessible and traceable, which should generate trust between stakeholders. However, the traceability of transactions, and ultimately of the crypto-currency, does not imply the traceability of users authenticated by an account address, or more precisely by a set of account addresses that are independent of each other. In this context, it can be complex to trace the individuals or legal entities owning the crypto-currency.
Crypto-currency is not the only use case supported by blockchain technology. The deployment of Ethereum in 2014, based on the use of smart contracts, opened up many other uses, in particular the protection of identifying data. In this area, the need for traceability versus furtivity can vary greatly from one use case to another. For example, on a blockchain that records the access of a worker owning an employment certificate to an industrial site, no information enabling the worker to be identified or his activity to be traced should appear. On the other hand, in the case of data collected by IoT sensors and processed by remote Edge devices, traceability of data and processing is desirable.
The thesis proposes to study different techniques for tracing digital assets on a blockchain, for stealthing their owners, and offering the possibility of auditing and identification by an authorised body. The aim is to build embedded devices, Edge or personal possibly embedding artificial intelligence, secured by hardware components, integrating different cryptographic solutions and account, data or identity wallet structures to meet the needs of the different use cases envisaged.
Self Forming Barrier Materials for Advanced BEOL Interconnects
Context : As semiconductor technology scales down to 10 nm and below, Back End of Line (BEOL) scaling presents challenges, particularly in maintaining the integrity of copper interconnects, where line/via resistance and copper fill are key issues. Copper (Cu) interconnections must resist diffusion and delamination while maintaining optimal conductivity. In the traditional Cu damascene process, metal barriers and a Cu seed layer are deposited by PVD to enable electrochemical copper deposition. As dimensions shrink, it becomes increasingly difficult to incorporate tantalum-based diffusion barriers, even with techniques like atomic layer deposition (ALD), as the barrier thickness must be reduced to just a few nanometers. To address this challenge, a self-forming barrier (SFB) process has been proposed. This process uses copper alloys containing elements such as Mn, Ti, Al, and Mg, which segregate at the Cu-dielectric interface, forming an ultra-thin barrier while also serving as a seed layer for electroplating.
Thesis Project: The PhD candidate will join a leading research team to explore and optimize materials for SFBs using Cu alloys. Focus areas include:
- Material Selection & Characterization: develop and analyze Cu alloy thin films by electrochemical and PVD methods to study their microstructure and morphology.
- Barrier Formation: Control alloy migration at the Cu/dielectric interface during thermal annealing and assess barrier effectiveness.
- Electrical & Mechanical Properties: Evaluate SFB impact on electrical resistance, electromigration, and delamination, especially in accelerated tests.
Required skills : Master's degree in electrochemistry or materials science with a strong interest in applied research. A pronounced interest in experimental work, skills in thin film deposition, electrochemistry and materials characterization (AFM, SEM, XPS, XRD, SIMS). You should be able to conduct bibliographic research and organize your work efficiently.
Work Environment: The candidate will work in a renowned laboratory with state-of-the-art 200/300 mm facilities and will participate in the CEA’s NextGen Project on advanced interconnects for high reliability applications.
Advanced functions for monitoring power transistors (towards greater reliability and increased lifespan of power converters for energy)
In order to increase the power of electronic systems, a common approach is to parallelize components within modules. However, this parallelization is complicated by the dispersion of transistor parameters, both initial and post-aging. Fast switching of Wide Bandgap (WBG) semiconductors components often requires slowdowns to avoid over-oscillation and destruction.
An intelligent driving scheme, including adjusted control, control of internal parameters of circuits and devices, as well as a feedback loop, could improve reliability, service life and reduce the risk of breakage.
The objectives of the thesis will be to develop, study and analyze the performance of control and piloting functions of power components, in silicon carbide (SiC) or gallium nitride (GaN), which could ultimately be implemented in a dedicated integrated circuit (ASIC type).
This thesis subject aims to solve critical problems in the parallelization of power components, thus contributing to eco-innovation by increasing the lifespan of power modules.