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

¨Preamorphization via ion implantation for salicide optimization

Département Technologies Silicium (LETI)

Laboratoire

01-09-2018

SL-DRT-18-1064

frederic.mazen@cea.fr

? Pre-amorphization implantation (PAI) for salicidation has been introduced during the last years to limit leakage junction, to optimize Schottky Barrier Height (SBH) and contact resistance of ultra-shallow junction by controlling roughness and limiting agglomeration of silicide. It seems also a good way to increase contact stability and yield, for example, by limiting silicidation close to the FD-SOI MOS transistor channel (piping defect). To take benefit and integrate this new step in the next CMOS technology generation and beyond, it seems necessary to accelerate development and understanding on this item. ? The thesis objectives will be to develop a process and to acquire a well understanding of the different interaction between pre-amorphization implantation conditions (species, energy, dose, etc.), and NiSi (or NiSiGe) formation in terms of metallurgical structure, roughness, and agglomeration. Interaction with dopant junction will be also studied. In parallel, piping evolution with PAI could be explored on morphological wafers. At the end, PAI physics understanding and impact on NiSi material will be discussed. Electrical performance, contact resistance, silicide stability and yield will be the figure of merit of developments. This work will have to permit a reduce development time to integer this new process in the next transistor Technology. Thesis will be achieved in collaboration with CEA-LETI and IM2NP. ? Based on the state of the art, and technological constraint, student will propose experiment, and characterization needs. He will be in charge of defining morphological and electrical test vehicle (short-loop) with adapted process flow, and following realization in clean room. Standard physical and electrical characterization as DRX in temperature, TEM (EDX, cross-section), SIMS, TLM and Rs measurement will be used. Thanks to IM2NP experience in Atom Probe Tomography (APT), 3D chemical analysis of NiSi will be a key to exhibit composition, segregation effect and understanding correlation between silicidation, PAI and contact parameters. TCAD simulation could be also used to define implantation conditions.

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Acoustic characterization of direct bonding energy

Département Technologies Silicium (LETI)

Laboratoire

01-11-2018

SL-DRT-18-1069

frank.fournel@cea.fr

Direct bonding is now more and more used for imager application for instance. One of its main parameter is the direct bonding energy but up to now, its characterization is based on a destructive technique as the DCB technique for instance. Last year, at the end of Ali Dekious Phd, a new way to characterize the bonding was discover using the acoustic microscopy. This acoustic characterization is non destructive and could perform a mapping of the bonding energy with a millimeter precision. This is very important as the bonding energy of the wafer edges could then be measured for the first time. But this technique is bright new and further developments are needed to have a reliable characterization. The aim of this project is to use the acoustic microscopy to characterize the bonding energy of direct bonding interface using standard commercial acoustic microscope. At first, a qualitative bonding energy mapping will have to be obtain. Then a research on the quantification of the acoustic bonding energy will be conducted using several standard bonded structure. This work will also need a good characterization and modelisation of the acoustic signal in order to use and to develop the model done by previous works.

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Water management in direct bonding

Département Technologies Silicium (LETI)

Laboratoire

01-10-2018

SL-DRT-18-1070

frank.fournel@cea.fr

Direct bonding is now used in many applications. Very recently, at CEA Grenoble, it has been shown that water can soak in a non-annealed direct bonding interface as well as to be removed from it. As water is one of the main parameter in hydrophilic direct bonding, controlling and accurately understand this phenomenon is very important for all hydrophilic direct bonding and not only for the Silicon/Silicon bonding. This study aim will be to study in detail the water management inside a direct bonding interface following different ways: A first part of the study will be to find a way to isolate the bonding interface. It is mandatory for all the accurate characterization of the direct bonding in order to have stable samples. It is also very interesting for many applications for which the edges are important and would like to get rid of this phenomenon. A second part of the study will be to continue the characterization of the water low dynamic at an annealed direct bonding interface. It will be also interesting to evaluate this flow during the annealing. The in or out dynamic will be evaluate regarding the bonding energy reached by the interface at the different annealing temperature. A last part of the study will be to evaluate accurately the water amount at the hydrophilic direct bonding interface of ?stable? samples. Varying this water quantity, a link will be done with the direct bonding energy and the possible defectivity which could appear under certain conditions. The student will be formed to all the needed technology used in direct bonding (chemistry, CMP, bonding, thermal annealing?) as well as all its usual characterization techniques (Infrared spectroscopy, acoustic microscopy, anhydrous bonding energy, XRR?)

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