Films minces d'oxydes à grande permittivité pour la nanoélectronique : organisation structurale et chimique et propriétés diélectriques

Despite the considerable research work devoted since ten years to the study of new high permittivity (κ) thin films for replacing silica in microelectronics, the relationships that exist between the structural/chemical and electrical properties of the films are not widely studied today. Thin Zr- and La-based oxide films, prepared by atomic layer deposition on silicon and/or germanium, are considered in this work. Quantitative parameters in relation with the organization at the nanometre level in the films and at the interfaces, determined by high resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) operated on a modern electron microscope, are directly connected toelectrical parameters such as κ and Dit (interface state density). After annealing under vacuum, the La2O3 sesquioxide can be obtained with its high permittivity hexagonal phase (κ ∼ 27) but is not stable. It is hygroscopic and forms with the silicon substrate an extended amorphous interfacial layer silicate in composition. The LaxZr1-xO2-δ (x ≤ 0.2) ternary oxide is not hygroscopic. On a silicon substrate and with x ∼ 0.2, it is stabilized in the cubic structure (κ ∼ 30) with annealing and forms a silica-rich interfacial layer with a spatial extension limited to 1-2 nanometres. On a germanium substrate and with x ∼ 0.05, the ternary is stabilized with the high permittivity tetragonal structure (κ ∼ 40) due to germanium diffusionwithin the film and develops in direct contact with the substrate. Lanthanum is essentially present near the interface and forms a germanate that lowers the Dit. This work has been developed in line with the European program REALISE.Malgré les gros efforts de recherche consacrés depuis dix ans à l'étude de nouveaux films minces d'oxyde à grande permittivité κ pour remplacer la silice en microélectronique, les relations qui existent entre les propriétés structurales/chimiques et électriques de ces films restent encore peu explorées. Des films minces d'oxydes à base de zirconium et de lanthane, préparés par dépôt chimique de couches atomiques (ALD) sur substrats de silicium et/ou germanium, font l'objet de ce mémoire. Les paramètres quantitatifs relatifs à l'organisation à l'échelle nanométrique dans ces films et aux interfaces, déterminés par microscopie électronique en transmission à haute résolution (MEHR) et spectroscopie de pertes d'énergied’électrons (EELS) mises en œuvre sur un microscope moderne, sont directement corrélés avec les propriétés électriques (κ et densité d'états d'interface Dit). Par recuit sous vide, le sesquioxyde La2O3 peut-être obtenu avec sa phase hexagonale de grande permittivité (κ ∼ 27) mais il s'hydrolyse rapidement et une couche interfaciale amorphe étendue de type silicate et de faible permittivité se forme à l'interface avec le silicium. L'oxyde ternaire LaxZr1-xO2-δ (x ≤ 0,2) est non hygroscopique. Sur substrat de silicium et avec x ∼ 0,2, il est stabilisé après recuit sous sa forme cubique (κ ∼ 30) avec une couche interfaciale amorphe riche en silice peu étendue. Sur substrat de germanium et avec x ∼ 0,05, il est stabilisé en contact direct avec le substrat sous sa forme tétragonale de plus grande permittivité (κ ∼ 40) grâce à la diffusion du germanium dans le film. Le lanthane, présent surtout près de l'interface, forme un germanate qui diminue Dit. Ce travail a été développé dans le cadre du programme européen REALISE

Films minces d'oxydes à grande permittivité pour la nanoélectronique : organisation structurale et chimique et propriétés diélectriques

Despite the considerable research work devoted since ten years to the study of new high permittivity (κ) thin films for replacing silica in microelectronics, the relationships that exist between the structural/chemical and electrical properties of the films are not widely studied today. Thin Zr- and La-based oxide films, prepared by atomic layer deposition on silicon and/or germanium, are considered in this work. Quantitative parameters in relation with the organization at the nanometre level in the films and at the interfaces, determined by high resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) operated on a modern electron microscope, are directly connected toelectrical parameters such as κ and Dit (interface state density). After annealing under vacuum, the La2O3 sesquioxide can be obtained with its high permittivity hexagonal phase (κ ∼ 27) but is not stable. It is hygroscopic and forms with the silicon substrate an extended amorphous interfacial layer silicate in composition. The LaxZr1-xO2-δ (x ≤ 0.2) ternary oxide is not hygroscopic. On a silicon substrate and with x ∼ 0.2, it is stabilized in the cubic structure (κ ∼ 30) with annealing and forms a silica-rich interfacial layer with a spatial extension limited to 1-2 nanometres. On a germanium substrate and with x ∼ 0.05, the ternary is stabilized with the high permittivity tetragonal structure (κ ∼ 40) due to germanium diffusionwithin the film and develops in direct contact with the substrate. Lanthanum is essentially present near the interface and forms a germanate that lowers the Dit. This work has been developed in line with the European program REALISE.Malgré les gros efforts de recherche consacrés depuis dix ans à l'étude de nouveaux films minces d'oxyde à grande permittivité κ pour remplacer la silice en microélectronique, les relations qui existent entre les propriétés structurales/chimiques et électriques de ces films restent encore peu explorées. Des films minces d'oxydes à base de zirconium et de lanthane, préparés par dépôt chimique de couches atomiques (ALD) sur substrats de silicium et/ou germanium, font l'objet de ce mémoire. Les paramètres quantitatifs relatifs à l'organisation à l'échelle nanométrique dans ces films et aux interfaces, déterminés par microscopie électronique en transmission à haute résolution (MEHR) et spectroscopie de pertes d'énergied’électrons (EELS) mises en œuvre sur un microscope moderne, sont directement corrélés avec les propriétés électriques (κ et densité d'états d'interface Dit). Par recuit sous vide, le sesquioxyde La2O3 peut-être obtenu avec sa phase hexagonale de grande permittivité (κ ∼ 27) mais il s'hydrolyse rapidement et une couche interfaciale amorphe étendue de type silicate et de faible permittivité se forme à l'interface avec le silicium. L'oxyde ternaire LaxZr1-xO2-δ (x ≤ 0,2) est non hygroscopique. Sur substrat de silicium et avec x ∼ 0,2, il est stabilisé après recuit sous sa forme cubique (κ ∼ 30) avec une couche interfaciale amorphe riche en silice peu étendue. Sur substrat de germanium et avec x ∼ 0,05, il est stabilisé en contact direct avec le substrat sous sa forme tétragonale de plus grande permittivité (κ ∼ 40) grâce à la diffusion du germanium dans le film. Le lanthane, présent surtout près de l'interface, forme un germanate qui diminue Dit. Ce travail a été développé dans le cadre du programme européen REALISE

Films minces d'oxydes à grande permittivité pour la nanoélectronique (organisation structurale et chimique et propriétés diélectriques)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Calculated and experimental electron energy-loss spectra of La2O3, La(OH)(3), and LaOF nanophases in high permittivity lanthanum-based oxide layers

International audienceUsing first principles methods, the O K energy-loss near-edge structure of cubic and hexagonal La2O3, La(OH)3, and LaOF phases have been calculated. These calculations support the identification of nanocrystalline phases evidenced experimentally by electron energy-loss spectroscopy (EELS) performed in a transmission electron microscope. The nanocrystals have been observed in atomic layer deposited La2O3 thin films developed for advanced metal-oxide-semiconductor field effect transistor applications. The presence of the nanophases can be explained by the hygroscopicity and the particular reactivity with fluorine of La2O3. These calculations provide a set of EELS fingerprints which will be useful for local phase identification in La2O3-based materials

Stable HfO2-based Layers Fabricated by RF Magnetron Sputtering

International audienceStructural and composition properties of HfO2-based layers fabricated by RF magnetron sputtering were studied by means of X-ray diffraction and transmission electron microscopy, Energy dispersive spectroscopy and ATR-FTIR techniques versus the deposition parameters and post-deposition annealing treatment. It was observed that the temperature at which amorphous-crystalline transformation of pure HfO2 layers occurs depends on deposition conditions. It was found that silicon incorporation in HfO2 matrix plays main role in the stability of the layers and allows to increase the temperature of layer crystallization up to 900-1100 °C

Stable HfO2-based Layers Fabricated by RF Magnetron Sputtering

International audienceStructural and composition properties of HfO2-based layers fabricated by RF magnetron sputtering were studied by means of X-ray diffraction and transmission electron microscopy, Energy dispersive spectroscopy and ATR-FTIR techniques versus the deposition parameters and post-deposition annealing treatment. It was observed that the temperature at which amorphous-crystalline transformation of pure HfO2 layers occurs depends on deposition conditions. It was found that silicon incorporation in HfO2 matrix plays main role in the stability of the layers and allows to increase the temperature of layer crystallization up to 900-1100 °C

High-k Hf-based layers grown by RF magnetron sputtering

International audienceStructural and chemical properties of Hf-based layers fabricated by RF magnetron sputtering were studied by means of x-ray diffraction, transmission electron microscopy and attenuated total reflection infrared spectroscopy versus the deposition parameters and annealing treatment. The deposition and post-deposition conditions allow us to control the temperature of the amorphous–crystalline phase transition of HfO 2-based layers. It was found that silicon incorporation in an HfO 2 matrix plays the main role in the structural stability of the layers. It allows us not only to decrease the thickness of the film/substrate interfacial layer to 1 nm, but also to conserve the amorphous structure of the layers after an annealing treatment up to 900–1000°

Electromagnetic modeling of plasmonic properties of gold nanoparticles embedded within a dielectric matrix deformed by swift heavy ions

International audienceThe growing number of fields in which are studied the localized plasmon surface resonance such as light management for energy, enhanced field spectroscopy, or for integrated optical telecommunications bellow the diffraction limit is driving the development of modeling methods of these systems. In this paper, the electromagnetic properties of ion-deformed gold, sphere, prolate, nanorods and nanowires embedded within a dielectric matrix are simulated in a spectral range from visible to infra-red by means of Auxiliary Differential Equations (ADE) coupled to a Finite Difference Time Domain (FDTD) method. The electromagnetic field distribution is investigated in gold nanostructures in order to evidence the local field enhancement effect characteristic of the Localized Surface Plasmon Resonance (LPSR)

Influence of nanopore surface charge and magnesium ion on polyadenosine translocation

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Combining HRTEM-EELS nano-analysis with capacitance-voltage measurements to evaluate high-kappa thin films deposited on Si and Ge as candidate for future gate dielectrics

International audienceAberration corrected transmission electron microscopy and electron spectroscopy are combined with electrical measurements for the quantitative description of the structural, chemical and dielectric parameters of rare earth/transition metal oxides thin films. Atomic structure near the interface and elemental profiles across the interface up to the surface of La-doped ZrO2 and Er-doped HfO2 films prepared by atomic layer deposition on Si(100) and Ge(100) are determined. Interfacial layers unavoidably form between the semiconductor substrate and the dielectric oxide after deposition and annealing. They are evidenced from a structural and chemical point of view. From the knowledge of the chemical extent of the interfacial layer and of the accumulation capacitance of the stack, it is possible to recover the dielectric constant of both the interfacial layer and the high-κ oxide layer constituting the stack using a multi-layers capacitor model approach. Oxides with permittivities higher than 30 are stabilized. Interfacial layers, silicate/germanate in composition, with permittivites, respectively, tripled/doubled compared to the one of SiO2 are evidenced