Scientific direction Development of key enabling technologies
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PhD : selection by topics

Technological challenges >> Emerging materials and processes for nanotechnologies and microelectronics
23 proposition(s).

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Electrochemical deposition of insulating polymer films

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0308

paul.haumesser@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The electrohoretic deposition is a well known technique to form polymeric coatings with a variety of materials such as polyetherimide (PEI). This technique usually requires the application of several (tens of) volts. Under such conditions, electrochemical reactions occur at the electrodes, such as solvent decomposition, that promote polymer precipitation at their surface. Recent results suggest that these electrochemical reactions are sufficiently active at much lower overpotentials (below 3V). This would enable deposition processes under mild conditions with improved control over the film properties. In this thesis, the mechanisms at play during the deposition of PEI under such mild conditions will be studied, with the aim of developing a process suitable for the fabrication of capacitors with high breakdown voltage. This approach will also be extended to other insulating polymers compatible with healthcare applications (such as packaging of wiring circuits for implant systems) or to hydrophilic and/or porous polymers for the encapsulation of biologic structures (cells, enzymes, bacteria) or cell filtration in biochips.

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Study of dynamic degradation and reliability of advanced GaN on Si power devices

Département Composants Silicium (LETI)

Laboratoire de Caractérisation et Test Electrique

01-10-2020

SL-DRT-20-0430

william.vandendaele@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

GaN-on-Si based power devices are now considered as the next generation of mass market devices for high frequency & low looses power converters (DC/DC, AC/DC or DC/AC). In this vision, LETI is developing its own pîlot line of GaN on Si power devices (CMOS compatible) from the GaN epitaxy to the final power module. These devices are supposed to operate dynamically between high voltage stage (650V and below) and high current state (> 20A) at high frequencies (> 100kHz). Statics and dynamic performances being proved, it is worth of interest to test and study reliability of these devices under high voltage stress and high temperature as well as under practical swithching conditions (hard/soft/ZVS). These studies aim to understand the underlying physical degradation mechanisms arising under operating conditions and ultimately to stabilize the technologie for industrial technological transfer. The PhD student will be responsible of : - Finalizing exisiting dynamic setups and create new ones especially concerning on-wafer switching test (limitations/feasibility) - In Depth study of HEMT electrical parameters degradation (Ron, Vt, Sw?) as well as Diode parameters (Vf, Sw) during DC or AC stress to determine the root cause of the degradation leading to reliability reduction. - Determination of Switching SOA of GaN based devices from LETI as well as studying new acceleration factors such as duty factor or switching frequency - Localization and Identification of Failure point and understanding of the Failure root cause through FA studies (IR or visible camera + FIB/MEB studies) - Proposal of new technological solutions to overcome some early failures and low realiblity issues The PhD student will be curious, open minded and team worker.

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Optimization of dielectric/GaN interface for MIS gate power devices

Département Composants Silicium (LETI)

Laboratoire Composants Electroniques pour l'Energie

01-09-2020

SL-DRT-20-0432

laura.vauche@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

To definitively penetrate into the power electronics market, one of the main challenges for GaN remains the development of a reliable normally-off HEMT solution. In the case of GaN-based MIS channel-High Electron Mobility Transistors (HEMTs), the dielectric/GaN interface properties are critical. The goal of the thesis is to optimize the dielectric/GaN interface for MIS gate power devices. For this, 1. The dielectric/GaN interface properties will be evaluated by XPS (X-ray Photoelectron Spectroscopy). This technique allows to study the oxidation degree at GaN surface. Additional analyses by ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) and HRTEM (High Resolution Transmission Electron Microscopy) will be carried out in order to characterize the materials chemical composition and crystalline structure. 2. GaN-based devices quality will be studied by transistor and capacitance electrical characterization (mobility, on-resistance, channel resistance, threshold voltage, hysteresis), as well as fine electrical measurements (interface state density extraction reliability). 3. The impact of processing steps (wet chemical cleaning, etching, stripping, thermal and plasma treatments)on interface quality will be evaluated, allowing to select the most appropriate MIS gate processing.

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Study of Vertical GaN Device Architectures

Département Composants Silicium (LETI)

Laboratoire Composants Electroniques pour l'Energie

01-10-2020

SL-DRT-20-0481

julien.buckley@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

LETI is currently transferring an AlGaN/GaN epitaxy-based power device technology on 200mm Silicon wafers to a well-established industrial partner in the field of power devices (Silicon, SiC,?) Current GaN transistor technologies that are available on the market have a lateral architecture. They allow to render electric power conversion circuits up to the several 10 kilowatt range. The implementation of a vertical architecture will allow to address power ranges above the megawatt. The work proposed in this PhD will involve a study aiming to evaluate the performance and physical properties at the basis of the operation of vertical devices using GaN substrates. The tasks will involve as well the management of the device fabrication (epitaxy, deposition, lithography, implantation) and electrical measurements. Finite element simulations (TCAD using Synopsys tools) will be performed in order to tune the dimensions of structures that will be included in a mask set and subsequently be used to test physical hypotheses to interpret the electrical results.

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Aluminum/ Silicon carbide nanocomposites obtained by laser powder bed fusion additive manufacturing process.

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire de Formulation des Matériaux

01-11-2020

SL-DRT-20-0483

mathieu.soulier@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Metal matrix composite composed of an aluminum metal matrix embedding silicon carbide inclusions is widely used in various industries from automotive to aerospace or defense. Such composites allow the reduction of the parts weight thanks to an increase of the Young modulus/density ratio drastically higher compared to steels or titanium alloys. The study aims at developing aluminum composites reinforced by nanosized silicon carbide particles to improve the material stiffness without compromising on the elongation to fracture criterion. In addition, shaping by an additive manufacturing process based on a laser powder bed fusion process (L-PBF) should allow further improvements in terms of weight reduction, thus fully complying with the strategical objectives of material savings and environmental impact. The first objective of the thesis is to develop the powder mixing process to obtain homogeneous and stable nanocomposite powder, using either a blade mixing to coat aluminum particles by the nano SiC, or a milling process to include the reinforcements inside the aluminum particles. For the case of blade mixing, the challenge is to identify process conditions that allow an homogeneous repartition of the nano-Sic within the solidified material. The second objective of the thesis is to test the potential of tailored specific nano-SiC reinforcements. To this end, the idea is to use the laser pyrolysis process that allows a modification of the surface chemistry to improve the SiC wettability and also limit its decomposition in the aluminum matrix.

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ultra low temperature solid phase recrystallization assited by nanosecond laser annealing

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0514

Pablo.ACOSTAALBA@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

During last years, great progress has been made in reducing the thermal budget required for the manufacture of microelectronics devices. Moreover, nanosecond laser annealing represents a very promising alternative for the integration of microelectronic devices whose thermal budget must be limited. Since very few years, CEA/LETI has started a very ambitious program on advanced thermal treatments for microelectronics. In this context, a nanosecond laser annealing equipment has been installed in the LETI clean room. This innovative process makes it possible to reach very high temperatures for extremely short durations (a few tens of ns). This implies that the thermal budget applied to the irradiated structures is very low. It has recently been demonstrated that nanosecond laser annealing can be used to obtain solid phase recrystallization of partially amorphized silicon layers. This method can be used to optimize different steps of the manufacturing processes, as for exemple dopant activation on source and drain. It is therefore fundamental to understand the physical mechanisms and to explore the impact of different parameters on the recrystallization kinetics in order to manage this process in basic materials such as Si and SiGe. This thesis aims evaluating the contribution of nanosecond laser annealing on the structural and electrical properties of different semiconductor stacks

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Development of innovative chalcogenide material etching processes for non-volatile memories and photonic

Département des Plateformes Technologiques (LETI)

Laboratoire Gravure

01-09-2020

SL-DRT-20-0625

christelle.boixaderas@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The patterning steps (etching / stripping / cleaning) have adverse effects on the properties of chalcogenide films. It is therefore essential to study this patterning brick in order to propose new dry etching solutions and associated post treatments. After a first phase of bibliographic research and training in clean room on tools necessary for future works, the student will propose a methodology allowing the understanding of the mechanisms of etching of the reference process and modifications of the GeSbTe (and other alloys) by surface analyzes (bottom and sidewall of the structures) It will propose and implement improvements to the reference process (chemistry, plasma parameters, etc.) that will ensure that the chalcogenide remains intact during the flow of memory fabrication. Then, he will have to choose the integrations and materials for a test vehicle in memory and Photonics. The challenge will be to make improvements to the reference process of the memory stack based on the study of the previous phase: stack etching, stripping, management of waiting times between stages. Finally, it would be interesting to measure the impact of the changes by electrical results on the memory cells (gain / loss on the intrinsic characteristics of a PCM memory).

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Innovative package using ultra-thin chip transfer on substrate (UTCoS)

Département Composants Silicium (LETI)

Laboratoire Packaging et 3D

01-07-2020

SL-DRT-20-0703

gabriel.pares@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The subject is in the field of advanced microsystems, which is a strategic axis for CEA-LETI associated with current packaging trends: extreme compactness, conformability and functionalization. The approach developed is unique and allows the carrying of ultra-fine chips ("substrate-less ") on any type of host substrates with a process adaptable to different bonding solutions including direct bonding or with an intermediate layer. It uses CEA-leti's expertise in ultra-thinning of layers, temporary and permanent bonding techniques, thin layer transfer on temporary carrier and advanced cutting techniques (plasma, laser). In addition, it uses advanced packaging technologies with thin FLEX substrates, molding encapsulation and additive technology interconnections (RDL, 3D printing and screen-printing). The proposed solution is generic and addresses many applications as CMOS image sensors, MEMS (sensors and piezo-electrics actuators), RF ICs (filters, switches, antenna arrays). The focus of the study will be on CMOS image sensor with passive and active focal plan curvature with the objective of realizing a first functional demonstrator.

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Surface physico-chemical properties modification by multi-scale nano-patterning

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0720

maxime.argoud@lcea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Over the past 20 years, surface patterning methods have been developed in the field of advanced lithography for microelectronics. These breakthrough techniques, such as directed self-assembly of block copolymers or nano-imprint lithography, appeared to be a credible low-cost alternative to traditional optical lithography methods. Many studies have demonstrated and confirmed this potential, up to the 300mm wafer scale, however these technologies have not been tranferred for CMOS applications, particularly because of the defectivity and the industrialization of the extreme UV lithography. The maturity of the various processes and materials developed, as well as the associated global understanding, now offers many opportunities for applications for which defectivity is not critical. In particular, the modification of the surface physico-chemical properties by nano-patterning, on several scales, using of the relatively low-cost patterning techniques previously mentioned, could address many application domains (optical properties, biotechnologies, self-assembly of chips ...). The thesis work will focus on the modification of surface physico-chemical properties by nano-patterning. The surface patterning will be achieved by advanced patterning technologies such as self-assembly of block copolymers, over a wide range of periods (from 20 to 200nm), directed or not, and also by nano-imprint lithography. A working axis will concern the implementation, and the associated understanding, of these patterning techniques. Various thin layers or bulk materials may be structured, and the physico-chemical properties obtained will be finely characterized. An original axis of the work will also focus on the multi-scale aspect of this pattering, from the point of view of patterning itself over a wide range of dimensions (from a few nm to several hundred nm), or from the dimension of the modified surfaces (from a few hundred nm² to several tens of cm²). Some properties can be applied to various application domains (optics, biotechnologies, chip self-assembly ...).

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Study of integraiton of 2D materials in RF devices

Département Composants Silicium (LETI)

Laboratoire Intégration et Transfert de Film

01-09-2020

SL-DRT-20-0739

lucie.levan-jodin@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Since the discovery of graphene (Nobel pice 2010 by Andre Geim), the enthusiasm for 2D materials has grown steadily. In fact, these materials have very remarquable properties that make them serious candidates to create new generations of high-performance electronic or optoelectronic devices, miniaturization, flexible devices and low energy consumption. The aim of the thesis is to develop new 2D-based radio frequency (RF) switch concepts for future wireless telecommunications systems. The work is multidisciplinary and will be carried out in close collaboration between two CEA institutes: IRIG will bring its expertise around the growth and characterization of the electrical properties of 2D materials and the LETI will bring its expertise on the integration of thin layers in devices and on design of RF switches. The Phd candidate will seek to identify the key points of this type of device and to improve our understanding of the mechanisms involved, especially when switching. It will develop the methods of transfer of the material into the device and seek to optimize the electrical contact between the 2D materials and the metal electrodes. Finally, it will develop the technological integration processes of switches in planar or vertical configurations, seeking to ensure compatibility with integration on Si for microelectronics.

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Advanced chemical analysis of organic light emitting diodes

Département des Plateformes Technologiques (LETI)

Laboratoire Analyses de Surfaces et Interfaces

01-10-2020

SL-DRT-20-0748

jean-paul.barnes@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The nanocharacterisation platform has recently installed several advanced characterisation techniques : a new time of flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectrometer (XPS). Both instruments are equipped with a novel argon cluster ion source that allows damage free analysis of organic layers such as those found in organic light emitting diodes (OLEDs). The lifetime of OLEDs may be limited by the electrical or environmental ageing or the organic layers contained in the device. For the development of OLEDs it is important to be able to characterise the degradation of organic layers. The objective of this PhD project is to develop the advanced TOF-SIMS and XPS protocols needed to quantify and understand the degradation of the layers. The development of specific sample preparation methods will be carried out in order to be able to analyse the same area of the sample using several different techniques. The candidate will work closely with the team at the CEA-LETI making the OLED devices and materials and the instrument suppliers.

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Transparent piezoelectric actuators for haptic

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-10-2020

SL-DRT-20-0756

gwenael.le-rhun@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The haptic technology (science of touch) is in full rise and attracts more and more interest from industrials in the fields of telephony or automotive. Piezoelectric actuators are used to generate vibrations on a tactile surface to produce a haptic feedback, thus facilitating (or augmenting!) interactions between the user and his environment. Some tactile surfaces, such as screen, dashboard or window, would ideally require the use of transparent actuators. However, thin film piezoelectric actuators are deposited on a silicon substrate and incorporate non-transparent layers (electrodes, etc.). Strong technological constraints, such as the crystallization temperature of the piezoelectric material (around 700 °C for the PZT), make the thin film deposition of transparent piezoelectric stacks on glass particularly complex, or impossible. LETI has recently developed an innovative technology for transferring one or more layers, for example PZT, from a silicon growth substrate to a host substrate such as glass (several patents). The objective of this thesis will be to design and realize transparent piezoelectric actuators on glass substrate for a haptic application. A state of the art on the subject will make it possible to establish the targeted specifications for the chosen device. Based on the knowledge and expertise available at LETI, the PhD student will work on the integration of materials (piezoelectric, electrodes, etc ...) allowing in particular obtaining a functional stack with the required transparency, as well as on the design and the realization of the actuators and their characterizations.

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Asymetrical pattern manufacturing for light managment

Département des Plateformes Technologiques (LETI)

Laboratoire Gravure

01-09-2020

SL-DRT-20-0781

slandis@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The introduction of augmented reality, especially on portable optical systems such as eyeglasses, requires the manufacture of specific diffraction gratings to generate immersive images in a very small volume. One of their specificities is that they have an asymmetrical geometry (inclined sidewalls) making them particularly complicated to manufacture with the standard processes used for micro systems and microelectronics.

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Development of an innovative method for identify the thermomechanical properties of thin films. Application to the design and manufacture of a microelectronic device

Département des Plateformes Technologiques (LETI)

Laboratoire Propriétés des Matériaux et Structures

01-10-2020

SL-DRT-20-0804

lionel.vignoud@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Frame and context: the design and manufacture of microelectronic devices require knowledge the thermomechanical properties evolution of the materials that make up the components. Based on experimental measurements, data processing and simulation tools (MATLAB), we propose to develop an innovative method for identifying the module E and the coefficient of thermal expansion of thin layers. We will apply this work to the manufacture of a microelectronic device. Work required: the student in engineering school or master's degree in mechanics and/or materials, will be trained and must master both the experimental measurement techniques used to characterize the materials (in a clean room environment) and the analysis and calculation tools that we will use in this study. He will work on the design, manufacture and reliability of microelectronic devices with different teams from LETI and ST Microelectronics. The objective is to limit component strain, optimize manufacturing steps and finally, make devices more reliable.

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Dopant activation in SiGe thin films: process optimization, characterization and numerical simulation

Département des Plateformes Technologiques (LETI)

Laboratoire

01-04-2020

SL-DRT-20-0817

sebastien.kerdiles@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

CEA-LETI has recently installed in its state-of-the-art cleanrooms a new annealing equipment based on a nanosecond pulsed ultraviolet laser. This innovative thermal treatment enables processes at very high temperatures with extremely short durations, leading to heat confinement within a few hundred nanometers below the surface. Thanks to these unprecedented features, such nanosecond laser process is forseen as the next annealing technology generation with huge expectations especially for electronic devices such as advanced CMOS, memories and microsystems (MEMS). In the framework of a european research project (MUNDFAB, with partners laboratories from Germany, Austria, Italy and Poland), CEA-LETI and CNRS-LAAS jointly propose a doctoral research work targeting the development, the optimization and the simulation of dopant activation processes in SiGe thin films by nanosecond laser annealing. To reach this goal, the PhD student will combine experimental work in cleanrooms, electrical and physical characterization and multi-physics numerical simulations. Nanosecond laser annealing will be investigated in ultra-thin semiconducting films containing high concentrations of dopants, introduced directly during the epitaxial film growth or by a subsequent ion implantation. The PhD student will explore the limits of this disruptive annealing technique. Various technological approaches will be explored to tentatively control the crystalline quality of the laser annealed films, the germanium and dopant segregation and the surface roughness. The candidate should have strong knowledge in physics of semiconductors, materials science and microelectronics. He/she should appreciate team work and be rigorous, creative and endowed with good summarizing skills.

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Doping and confinement impacts on TiSi2 formation assisted by nanosecond laser annealing. Application to contacts for advanced imaging technologies

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0821

sebastien.kerdiles@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Imaging technologies based on silicon devices are today widely spread in mobile phones, sensing and automotive applications. Many technical optimizations have enabled their increasing market penetration. Currently, in the optical sensor region, namely the pixels, electrical contacts are based on a silicide last integration, in which titanium silicide is formed after contact via etching. The electrical resistance of these ?TiSi' contacts is still too high and exhibits a strong lot-to-lot and within wafer dispersion. The current process will then not be a realistic option for mass production in the coming years. Recent improvements have been demonstrated by combining optimized Ti/TiN deposition with a disruptive thermal treatment available at CEA-LETI, namely the nanosecond laser annealing. The thesis work proposed targets to further develop these processes and understand the corresponding mechanisms and good results. This doctoral research is a collaboration between IM2NP (Institut Matériaux Microélectronique Nanosciences de Provence) in Marseille, CEA-LETI in Grenoble and STMicroelectronics R&D center in Crolles. The main goal of this thesis is to integrate and optimize innovative processes enabling good electrical contacts for advanced imaging technologies being developed in Crolles fab. First, the study will focus on the effects of doping and substrate nature on the titanium silicide formation. P+ and polycrystalline silicon active regions will be explored through sheet resistance measurements, X-ray diffraction and atom probe tomography. A set of optimal conditions will be determined. Then, the impact of the confinement on the silicide contact formation will be investigated using patterned production wafers. Finally, an innovative integration scheme will be proposed and tested on production wafers combining optimal preparation and deposition conditions with nanosecond laser annealing. This new path will be evaluated in terms of yield through electrical and optical characterizations.

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Optomechanical Cristal coupled to a SAW for microwave to infrared transduction

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-10-2020

SL-DRT-20-0832

guillaume.jourdan@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The most promising quantum computing platforms today are operated at very low temperatures at microwave frequencies, while telecommunication networks capable of preserving information in unconventional states (superposition, entanglement) use infrared (IR) photons at room temperature. Current frequency conversion means offer poor conversion efficiencies (10-6), which make them unusable for processing quantum information. A very highly efficient optical microwave converter is an essential step in linking these two frequency domains and creating a genuine network of distributed quantum computers (quantum internet). The proposed thesis topic aims to develop such a converter by exploiting the multi-scale coupling properties of mechanical nanoresonators. The first technological bricks have recently been produced with coupled mechanical/IR or mechanical/microwave systems in quantum regime. The aim here is to design an optomechanical crystal coupled to an IR resonator. The optomechanical crystal operating at microwave frequencies (GHz) will be actuated with the help of a SAW (Acoustic Wave Surface) powered by a microwave wave. This type of system offers a very low rate of insertion of conventional noise into the conversion process. The AlN deposition will be carried out in Leti's clean room, and then the subsequent steps can be continued at the PTA (academic clean room) which offers more flexibility in terms of the manufacturing process. A collaboration is in place with the Néel Institute (CNRS) in Grenoble to characterize these ultra-low temperature (<100mK) devices. This will allow the devices to be tested and compared with the expected performance. It will then be necessary to review the modelling and design based on the measurements in order to ensure that all phenomena are understood.

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SAB bonding study for heteristructure elaboration

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0874

frank.fournel@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

This study aim is on the fundamental bonding of ultra high vacuum bonding done after ionic activation (SAB). One goal is to investigate the direct bonding mechanism including this specific bonding technic. All the characterization used to put in place the actual silicon direct bonding mechnisme will then be used to evaluate the SAB bonding. The huge bonding energy since room temperature could lead to very interesting impact on our direct bonding mechanism as well as on, for instance, the Smart Cut one. In parallel, the elaboration of heterostructure using SAB will be evaluated will the possibility to elaborate strain Germanium or Silicon thin film which could be very useful in optoelectronic.

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Wettability and adhesion mechanism of adhesive in hybridized structure , functionalized and underfilled , based on Cu pillars interconnexions

Département d'Optronique (LETI)

Laboratoire Assemblage et Intégration pour la Photonique

01-10-2020

SL-DRT-20-0906

nacer.aitmani@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The assembly of electronic components using the flip chip technology are widely present in the mass product markets as mobile phones, civilian ,medical or military market.the high count number of input output which can be higher that one million , with low pixel pitch , and small hybridization height .The underfilling of these structures is a key point for the robustness and the reliability of such packaging.It's a big challenge to perform such filling operation in hybridized components using the copper pillars interconnection technology ,without voids defects or adhesion weakness or variation in the adhesive thickness. The study proposed here is to inject in a gas phase mode a wetting product wich cover all the internal surface to be underfilled .This nanometric layer has to be characterized exhaustively to check its presence and thickness and how it react with all the encountered surfaces , the behaviour with parameters like temperature , queue time after deposition , and the usual reliability cycling programs. The key parameter to understand here is the adhesion of the underfilling époxy adhesive to all the surfaces and what is the mechanism of adhesion and the impact on reliability of the assembly with this wetting material, by chemical and thermal characterizations. Understand what is the major contribution of this treatment to the microelctronic industry.

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Innovative Piezoelectric Materials elaborated by Pulsed Laser Deposition (PLD)

Département des Plateformes Technologiques (LETI)

Laboratoire

01-09-2020

SL-DRT-20-0970

florian.dupont2@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

In this thesis work, the PhD student will first evaluate the conditions to promote epitaxial growth of innovative materials like LNO. The objective is to create conditions promoting the required crystalline orientations for RF filters application. PLD deposition technique will be used to deposit this ?template? and/or complex oxides on silicon, with wafer diameters compatibles with the standards of microelectronic industry. This work will benefit from a large variety of physico-chemical characterization techniques available in LETI platforms, including Xray Diffraction, XPS, Auger, HRTEM to evaluate interfacial structure, and piezoelectric measurements. In a second time, those layers will be integrated into simplified structure tests to evaluate the impact of their properties on final device performances.

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Mechanical and electrical contact study of micro-inserts hybridization

Département d'Optronique (LETI)

Laboratoire d'assemblage et de Packaging Photonique

SL-DRT-20-0974

natacha.raphoz@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

In microtechnology, hybridizations are carried out, in particular optical sensor pixel matrix hybridizations on their read circuitry (CMOS). Connections, at each pixel, must be relevant mechanically as well electrically. During the thesis, an innovative process of hybridization based on micro-insertion will be developed and implemented. You should have to design and manufacture micro-inserts (typically nail-shape micro-insert) which have "to be driven" in metal pads (eg aluminum) with good electrical contact and sufficient mechanical strength not to risk any deshybridization. During the thesis, you will try to model and simulate this micro-insertion. In parallel, in order to evaluate the insertion and de-insertion forces and to evaluate the electrical resistance of connection, two characterization benches should be developed. You will also be involved in the process of hybridization and in the joint optimization of the design - process point.

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Innovative Mixed RF and low power devices integration in view of advanced fdsoi SOC

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-10-2020

SL-DRT-20-1027

claire.fenouillet-beranger@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Connected mobile devices are becoming a strategic imperative in order to remain attractive, improve efficiency and competitive for advanced electronic applications. The wireless revolution where Laptops, Smartphone's, tablets, TVs, vehicles and enterprises are connected in a cloud style environment makes possible communication anywhere at any time. Recent developments in wireless communications with the emergence of advanced radio-frequency standard such as LTE, LTE-A and 5 G have brought numerous challenges. The most critical challenge is to provide higher levels of integration with more power efficiency and cost-effective solutions on the same-chip. In parallel to the development of nanometer CMOS as well as beyond-CMOS device technologies for switching, memory and analog functions, the increasing need to integrate various (heterogeneous) technologies (e.g. RF communication, power control, passive components, sensors, actuators) helps to migrate from the system board-level into the system-in- package (SiP) or to the system-on- chip (SoC). In fact, mobile System-on-Chip (SoC) with heterogeneous integration of multiple technologies has truly revolutionized the semiconductor industry. Thanks to the trap-rich Silicon-on-Insulator (SOI) substrate invented at UCL and developed in collaboration with SOITEC, RF SOI presents outstanding RF performance. In addition, the presence of the buried oxide layer not only reduces the junction capacitance but also offers the opportunity of using high resistivity substrate to reduce substrate related RF losses and coupling. However in case of SoC integration the trap-rich is not suitable all across the wafer and localized solutions should be envisaged. Fabrication on a 28FDSOI 300mm platform of specific RF stuctures Characterization of the substrate impact (HR, trap rich, etc ?) on the RF figure of merit Imagine and integrate new technological process schemes to implement localized ?trap-rich like' area before or after FDSOI device realization. Integrate some technological modules on new designed structures and electrical caracterization

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Development and characterization of advanced tunnel/recombination layers for 2T and 3T tandem integration

Département des Technologies Solaires (LITEN)

Laboratoire HETerojonction

01-10-2020

SL-DRT-20-1092

delfina.munoz@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Today, single junction silicon technology dominates the photovoltaic market, with more than 90 % of market share. However, the power conversion efficiency of silicon solar cells, with a reported record at 26.7 %, has neared its theoretical limit (29 %). To reduce thermalization losses and push efficiency further, silicon cells have been coupled to higher band gap semi-conductors to form tandem cells. Coupling silicon to perovskites appears as a particularly promising solution since perovskites show high performance (25.2 % power conversion efficiency has been reached in a few years), band-gap and thickness tunability and processing versatility. Therefore, silicon/perovskite tandems have the potential to become a high-efficiency technology in the future of photovoltaics. Since 2015, several demonstrations have already been published, either in 2-terminal configuration (2T, both cells connected in series) or in 4-terminal architecture (4T, cells stacking), with record efficiencies above 29 % today. One of the main challenges is the junction between the two sub-cells, which must ensure electrical behavior of charge passage without loss by recombination or optics. Currently transparent conductive oxides are the most used, but they have significant parasitic absorption with associated losses. In this thesis, we aim to develop new materials for the interface layer of a tandem perovskite / heterojunction cell with adaptation of optical index by different techniques and with the two possible configurations, in tunnel junction or in recombination and then characterize electrically, optically and morphologically. In addition, the electrical and optical materials simulation will optimize the complete cell in the different configurations. Finally, stability and integration studies will be done on the most promising junctions.

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