Neste trabalho foram fabricados e caracterizados capacitores MOS com camada dielétrica de oxinitreto de silício de diferentes composição química, depositada pela técnica de PECVD a baixa temperatura, com o intuito de estudar suas propriedades dielétricas e de interface visando à aplicação deste material em dispositivos MOS e de filme fino. Os capacitores foram fabricados sobre lâminas de silício do tipo p que passaram pelo processo de limpeza química inicial, seguida da deposição da camada dielétrica, fotogravação, metalização e sinterização. Os filmes de SiOxNy, utilizados como camada dielétrica, foram depositados pela técnica de PECVD à temperatura de 320ºC variando os fluxos dos gases precursores de forma a obter filmes com diferentes composições químicas. Os capacitores MOS foram caracterizados por medidas de capacitância e corrente em função da tensão, de onde foram extraídas a densidade de estados de interface, a densidade de carga efetiva, constante dielétrica e campo elétrico de ruptura dos filmes. Os resultados mostraram uma variação linear da constante dielétrica do filme em função da concentração de nitrogênio, indo do valor de 3,9, correspondente ao dióxido de silício estequiométrico (SiO2) à 7,2 correspondente ao nitreto de silício estequiométrico (Si3N4). Também observamos que o nitrogênio é uma barreira eficiente à difusão de impurezas através do dielétrico. Porém, notamos uma grande dispersão de duas ordens de grandeza nos valores da carga efetiva (Nss) e de densidade de estados de interface (Dit). Por outro lado, controlando algumas variáveis de forma a manter constante o valor de Nss ( ~1012 cm-2), observamos uma variação de Dit em função da concentração de nitrogênio no filme, esta variação porém é pequena comparada com a dispersão de duas ordens de grandeza observada, que atribuímos assim a fatores externos. O menor valor obtido de Dit foi de 4,55.1010 eV-1.cm-2, que é ótimo para um filme obtido por PECVD, sem nenhum tratamento térmico e melhor que os reportados na literatura para dielétricos obtidos por técnicas que utilizam altas temperaturas (LPCVD-800ºC e oxinitretação térmica – 1100ºC). Assim, podemos concluir que a técnica de PECVD é promissora para a obtenção de dielétricos a baixas temperaturas. / In this work, MOS capacitors with different chemical composition silicon oxynitride insulating layer, deposited by PECVD technique at low temperature were fabricated and characterized, in order to study its dielectric and interface properties, seeking its aplication as insulating layer in MOS and thin films devices. The MOS capacitors were fabricated onto p-silicion wafers previously cleaned by a standard process, followed by the insulating layer deposition, photolitography, metalization and sinterization. The SiOxNy insulating layer was deposited by the PECVD technique at 320ºC changing the precursor gases flows to obtain films with different chemical compositions. The MOS capacitors were characterized by capacitance and current vs. voltage measurements, from where the interface state density (Dit), the effective charge density (Nss), the dielectric constant (k) and the film electrical breakdown field (Ebd) were extracted. The results showed a dielectric constant varying linearly as a function of the films nitrogen concentration, going from a value of 3.9, corresponding to stoichiometric silicon dioxide (SiO2) to a value of 7.2, corresponding to stoichiometric silicon nitride film (Si3N4). We also observed that nitrogen is an efficient diffusion barrier against contaminants. However, a large dispersion, about two orders of magnitude, in the effective charge and in the interface state density was observed. On the other hand, controlling some variables so as to keep the Nss value constant (~1012 cm-2) we observed a Dit variation as a function of the film nitrogen concentration, this variation is small when compared with the observed dispersion of two orders of magnitude, thus attributed to external factors. The smallest obtained Dit was 4.55.1010 eV-1.cm-2, which is unexpected for a PECVD film without any anealing process and is better than the values reported in the literature for dielectrics obtained at high temperatures techniques (as LPCVD – 800ºC and thermal oxynitridation – 1100ºC). Therefore, we can conclude that the PECVD technique is promising for obtaining low temperature dielectrics.

Zircônia 3YTZP apresenta propriedades excelentes à temperatura ambiente, mas estas propriedades são afetadas pelo aumento da temperatura pois esta age negativamente sobre o mecanismo de transformação de fase induzida por tensão, que fortalece a tenacidade da matriz. A adição de Si3N4 e SiC em uma matriz de 3YTZP é muito interessante porque conduz à formação de oxinitreto de silício, melhorando as propriedades mecânicas tais como dureza e tenacidade, mas esta adição está limitada por várias dificuldades que se apresentam durante o processamento e sinterização destes materiais. Neste trabalho foi estudada a obtenção, por sinterização sem pressão, do compósito Y-TZP/Si2N2O, partindo-se da adição de 20vol%Si3N4-SiC em uma matriz de zircônia dopada com 3mol% de Y2O3 - 3YTZP, utilizando-se Al2O3 e Y2O3 como aditivos de sinterização. A mistura foi moída e moldada por prensagem isostática a frio. Amostras foram sinterizadas a 1500º, 1600º e 1700ºC por 2h sem pressão e em atmosfera ambiente, utilizando-se um leito de nitreto de silício. Após sinterização, as amostras foram caracterizadas por difração de raios-X. Foram medidas a densidade, tenacidade, dureza e resistência mecânica à flexão em temperatura ambiente. A estrutura do material foi observada em microscopia eletrônica de varredura e de transmissão, com mapeamento químico, para verificar a homogeneidade e morfologia das fases do compósito. A formação de Si2N2O foi observada no material sinterizado devido à reação entre os pós adicionados. O material obtido apresentou aumento de tenacidade e dureza com o aumento de temperatura de sinterização. As amostras apresentaram boa resistência à oxidação a 1000ºC. / Zirconia 3YTZP presents excellent properties at room temperature. These properties decrease as the temperature increases because high temperature acts negatively over the stress induced transformation toughening in the matrix. The addition of Si3N4 and SiC in a Y-TZP matrix is very interesting because leads to formation of silicon oxynitride and it increases the mechanical properties like toughness and hardness. Certainly the mechanical properties increment is limited by several difficulties which have appeared during processing and heating of these materials. This paper studies the Y-TZP/Si2N2O pressureless sintered composite, under different temperatures, showing the behavior of 20vol%Si3N4-SiC when added in YTZP matrix and heated under no pressure system. Al2O3 and Y2O3 were used as sintering aids. The mixture was milled and molded by cold isostatic pressure. Samples were heated at 1500º, 1600º and 1700ºC x 2h without pressure under atmospheric conditions using Si3N4 bed-powder. Samples were characterized by XRD and density, hardness, toughness, bending strength were measured. The structure of the material was observed in SEM/TEM/EPMA to verify the distribution and composition of the materials in the composite and the contact between filler surface and the matrix. The formation of SiON2 was observed in the sintered material due to reaction between both nitride and carbide with Y-TZP matrix. Furthermore the material showed an increment of both hardness and toughness as temperature increases. The samples presented considerable resistance to oxidation below 1000ºC.

Le but de ce travail est d’étudier l’effet de la vapeur d’eau contenue dans le plasma sur la composition et la vitesse de dépôt des couches minces d’oxynitrures de chrome déposées par pulvérisation cathodique magnétron réactive avec l’air contenant différentes teneurs en vapeur d’eau (humidité relative). Les techniques d’analyses par faisceau d’ions énergétiques : RBS et réactions nucléaires nous ont permis de déterminer les concentrations relatives des éléments déposés. Les profils d’hydrogène et d’azote ont été déterminés par RNRA et Tof- SIMS. La liaison chimique a été identifiée par LEEIXS et XPS. Les mesures XPS ont dévoilé la présence d’une phase autre que Cr, CrN, Cr2O3 et CrO2 ; cette nouvelle phase possède une stoechiométrie (CrO2)3-N. La teneur en Cr et ses composés varie en fonction du flux et de l’humidité relative de l’air. En mode métallique de la pulvérisation cathodique, la stoechiométrie Cr2O3 est majoritaire en coexistence avec de faibles teneurs et CrN, CrO2 et (CrO2)3-N alors qu’en mode composé, c’est la stoechiométrie CrO2 qui prédomine./ The aim of this work is to study the stoichiometry of chromium oxynitride thin films deposited by reactive magnetron sputtering in presence of air with various relative humidities. Ion Beam Analysis methods: RBS (Rutherford Backscattering Spectroscopy) and resonant nuclear reaction (RNRA) were used to determine the thickness and the composition of the films. Hydrogen and nitrogen profiles were obtained by RNRA and Tof-SIMS. The chemical bonds were investigated by XPS and LEEIXS. The chromium metallic and chromium compounds concentrations were measured versus the flow and relative humidity of the air. During sputtering in metallic mode, Cr2O3 stoichiometry is observed with low contents of CrN, CrO2 and (CrO2)3-N whereas in compound mode the CrO2 stoichiometry predominates.

Nitrogen rich glasses in the systems Ca-Si-O-N, Sr-Si-O-N and AE-Ca-Si-O-N (AE = Mg, Sr and Ba) have been prepared using a novel glass-synthesis route. The limits of the glass forming regions in the Ca and Sr systems and substitution limits in the AE-Ca-Si-O-N systems have been determined and physical properties of the glasses measured. Transparent glasses were obtained for a few specific compositions in the Ca-Si-O-N and Mg-Ca-Si-O-N systems. All other glasses were found to be translucent gray to opaque black, with the coloration of the glasses depending on the modifier. Small inclusions of Ca/Sr silicides and, in much smaller amounts, elemental Si are believed to be responsible for their poor transparency. A large glass forming region was found for the Ca-Si-O-N system, with glasses retaining up to 58 e/o N and 42 e/o Ca. In comparison, a more narrow glass forming region was found for the corresponding Sr system, with glasses retaining up to 45 e/o N and 39 e/o Sr. The glass formation was found to depend on reaction kinetics and precursors used. A strong exothermic reaction was observed at temperatures 650–1000oC, providing improved conditions for reaction kinetics upon further heating. Physical property measurements for the Ca and Sr glasses showed that glass transition and crystallization temperatures, viscosity, hardness, Young’s modulus and shear modulus depend strongly on the nitrogen content and that these properties increase approximately linearly with increasing nitrogen content. Glass density and refractive index are also dependent on the modifier element and content, in particular for the Sr glasses. Glasses AE-Ca-Si-O-N, with approximately constant (Ca/AE): Si:O:N ratios, showed that mixed modifier glass properties, such as density, molar volume, glass transition temperature, hardness, refractive index can be related to the effective cation field strength of the modifiers.

<p>Silicon ceramics are popular in both commercial applications and material research. The purpose of this thesis is to present measurements and analysis of four different silicon ceramics: á, â and ã phases of silicon nitride and silicon oxynitride using soft x-ray spectroscopy, which analyses the electronic structure of materials by measuring the absorption and emission of x-ray radiation. Absorption and emission spectra of these materials are presented, many of which have not be previously documented. The results are compared to model spectra and together they provide information about the electronic structure of the material.</p><p>Assignments of emission features to element, orbital, and site symmetry are performed for each material. Combinations of silicon and nitrogen emission spectra provide insight into the strained bonding structure of nitrogen. It is concluded that p-dð interaction plays a role in the bonding arrangement of nitrogen and oxygen sites within these structures. The emission features of non-equivalent silicon sites within ã-Si3N4 are identified, which represents some of the first analysis of same element, non-equivalent sites in a material.</p><p>Silicon absorption and emission spectra were plotted on the same energy scale to facilitate measurement of the band gap. Since previously measured band gaps are not well represented in literature, the measured band gaps were compared to values predicted using DFT calculations. The band gap values are in reasonable agreement to calculated values, but do not vary as widely as predicted.</p>

<p>Silicon ceramics are popular in both commercial applications and material research. The purpose of this thesis is to present measurements and analysis of four different silicon ceramics: á, â and ã phases of silicon nitride and silicon oxynitride using soft x-ray spectroscopy, which analyses the electronic structure of materials by measuring the absorption and emission of x-ray radiation. Absorption and emission spectra of these materials are presented, many of which have not be previously documented. The results are compared to model spectra and together they provide information about the electronic structure of the material.</p><p>Assignments of emission features to element, orbital, and site symmetry are performed for each material. Combinations of silicon and nitrogen emission spectra provide insight into the strained bonding structure of nitrogen. It is concluded that p-dð interaction plays a role in the bonding arrangement of nitrogen and oxygen sites within these structures. The emission features of non-equivalent silicon sites within ã-Si3N4 are identified, which represents some of the first analysis of same element, non-equivalent sites in a material.</p><p>Silicon absorption and emission spectra were plotted on the same energy scale to facilitate measurement of the band gap. Since previously measured band gaps are not well represented in literature, the measured band gaps were compared to values predicted using DFT calculations. The band gap values are in reasonable agreement to calculated values, but do not vary as widely as predicted.</p>

With device scaling, the current optical lithography technique is reaching its technological limit to print small features. Extreme Ultra-Violet (EUV) lithography has shown promise to print extremely thin lines reliably and cost-effectively. Many challenges remain before introducing EUV to large scale manufacturing. The main challenge addressed in this study is particle removal from EUV mask surfaces (CrON1, CrON2, and fused silica) and thermal oxide (SiO₂). Effective pre-clean procedures were developed for each surface. As chemical cleaning methods fail to meet SEMATECH criteria, addition of megasonic energy to EUV mask cleaning baths is seen as a promising cleaning methodology. As the requirement to print fine lines needs to be met, all materials used in EUV mask fabrication either absorb the incident EUV wavelength light or reflect it. Therefore, the masks used in the industry will be reflective instead of the conventional transmissive masks. Also, for the same reason, no protective pellicle can be used leading to all the surfaces unprotected from particle contamination. To avoid the detrimental effect of the particle contamination, a cleaning study for nano-particle removal was performed. A dark field microscope was utilized to study the removal of gold nano-particles from surfaces. The cleaning procedures utilized H₂SO₄ and NH₄OH chemistries with and without megasonic irradiation. The cleaning variables were bath concentration, temperature, and megasonic power. The contamination variables were the gold nanoparticles charge and size, from 40nm to 100nm. For 100 nm negatively charged gold nano-particles deposited on a CrON1 surface, a 1:10 H₂SO₄:DI bath at boiling temperature (101°C) without megasonics gave high particle removal efficiency (PRE) values as did a 1:10 H₂SO₄:DI bath at 35°C with 100W megasonics. Comparison of removal of poly diallyl-dimethyl ammonium chloride (PDAC) coated and uncoated gold nano-particles deposited on a CrON1 surface using dilute H₂SO₄ baths indicated that the coated, positively charged nano-particles were more difficult to remove. PRE trends for different baths indicate surface dissolution (shown to be thermodynamically favorable) as the particle removal mechanism. However, experimental etch rates indicated minimal surface etching in a 10 minute bath. Increased surface roughness indicated possible local galvanic corrosion at particle sites. Low surface etching results meet SEMATECH requirements. During the fused silica surface cleaning study, particle charge (negative) and size (100 nm) of the contamination source and cleaning bath chemistry (NH₄OH) were kept constant. Low PREs were obtained at room temperature for all NH₄OH bath concentrations; however, high PREs were obtained at an elevated temperature (78°C) without megasonics and at room temperature in more dilute chemistries with megasonic power applied. Similar PRE trends were demonstrated for thermal SiO₂ surfaces. The experimental etch rates of the thermal SiO₂ agree with published values.

La présente thèse s’inscrit dans un projet collaboratif de type CEFIPRA entre l’Inde (Dr. Ravi Kumar, Department of Metallurgical and Materials Engineering, Indian Institute of Technology-Madras (IIT Madras), Chennai) et la France (Dr. Samuel Bernard, Institut Européen des Membranes, CNRS, Montpellier). Les travaux de thèses se sont consacrés à la synthèse de céramiques de type non-oxyde autour de systèmes binaires (nitrure de silicium et nitrure de bore) et ternaires (Si-M-N, B-M-N (M=Ti, Zr, Hf)) à partir de précurseurs moléculaires et polymères, i.e., la voie polymères précéramiques ou PDCs. L’idée principale de ce travail est de former des structures nanocomposites à partir des systèmes ternaires dans lesquelles des nanocristaux de nitrures métalliques (M=Ti, Zr, Hf) se développent pendant la synthèse du nitrure de silicium et du nitrure de bore. Une caractérisation complète allant des polymères aux matériaux finaux a été conduite. Ces matériaux ont ensuite été préparés sous forme de composés mésoporeux (monolithes) en couplant la voie des polymères précéramiques à une approche de nanomoulage. Ces monolithes à haute surface spécifique et mésoporosité interconnectée ont alors été appliqués comme support de nanoparticules de platine pour l’hydrolyse du borohydrure de sodium pour générer de l’hydrogène. Les performances en tant que support de catalyseur ont été évaluées en termes de volume d’hydrogène libéré et de reproductibilité. Nous avons montré que les nanocomposites TiN/Si3N4 de surface spécifique très élevée présentent les meilleures performances grâce à l’activité catalytique du Si3N4 amorphe, de la présence de TiN nanométrique et de l’effet synergétique entre les nanoparticules Pt, le TiN nanostructuré et le Si3N4 amorphe. En preuve de concept, nous avons montré que ces structures nanocomposites étaient multifonctionnelles: elles peuvent être appliquées en tant que supports d’électro-catalyseurs et matériaux d’électrodes dans les piles à combustibles et les super-condensateurs, en particulier pour ceux contenant des matériaux lamellaires 2D et du carbone libre. / The thesis has been funded by a collaborative research partnership between Indian (Dr. Ravi Kumar, Department of Metallurgical and Materials Engineering, Indian Institute of Technology-Madras (IIT Madras), Chennai) and French institutes (Dr. Samuel Bernard, European Membrane Institute, CNRS, Montpellier), IFCPRA/CEFIPRA. It is focused on the synthesis, and characterization of binary (silicon nitride and boron nitride) and ternary (Si-M-N, B-M-N (M = Ti, Zr, Hf)) ceramics which are prepared through a precursor approach based on the Polymer-Derived Ceramics (PDCs) route. The idea behind the preparation of the ternary systems is to form nanocomposite structures in which metal nitrides (M = Ti, Zr, Hf) nanocrystals grow during the synthesis of silicon nitride and boron nitride. A complete characterization from the polymer to the final material is done. Then, these materials have been prepared as mesoporous monoliths coupling the PDCs route with a nanocasting approach to be applied as supports of platinum nanoparticles for the hydrolysis of liquid hydrogen carriers such as sodium borohydride. The performance as catalyst supports has been evaluated in terms of volume of hydrogen released and reproducibility. We showed that the very high specific surface area TiN/Si3N4 nanocomposites displayed the best performance because of the catalytic activity of amorphous Si3N4, the presence of nanoscaled TiN and the synergetic effect between Pt nanoparticles, nanoscaled TiN and amorphous Si3N4. Interesting, these materials are multi-functional as demonstrated as a proof of concept: they can be applied as electrocatalyst supports, electrode materials for fuel cells and supercapacitors, in particular those containing 2D layered materials and free carbon.

Neste trabalho foram fabricados e caracterizados capacitores MOS com camada dielétrica de oxinitreto de silício de diferentes composição química, depositada pela técnica de PECVD a baixa temperatura, com o intuito de estudar suas propriedades dielétricas e de interface visando à aplicação deste material em dispositivos MOS e de filme fino. Os capacitores foram fabricados sobre lâminas de silício do tipo p que passaram pelo processo de limpeza química inicial, seguida da deposição da camada dielétrica, fotogravação, metalização e sinterização. Os filmes de SiOxNy, utilizados como camada dielétrica, foram depositados pela técnica de PECVD à temperatura de 320ºC variando os fluxos dos gases precursores de forma a obter filmes com diferentes composições químicas. Os capacitores MOS foram caracterizados por medidas de capacitância e corrente em função da tensão, de onde foram extraídas a densidade de estados de interface, a densidade de carga efetiva, constante dielétrica e campo elétrico de ruptura dos filmes. Os resultados mostraram uma variação linear da constante dielétrica do filme em função da concentração de nitrogênio, indo do valor de 3,9, correspondente ao dióxido de silício estequiométrico (SiO2) à 7,2 correspondente ao nitreto de silício estequiométrico (Si3N4). Também observamos que o nitrogênio é uma barreira eficiente à difusão de impurezas através do dielétrico. Porém, notamos uma grande dispersão de duas ordens de grandeza nos valores da carga efetiva (Nss) e de densidade de estados de interface (Dit). Por outro lado, controlando algumas variáveis de forma a manter constante o valor de Nss ( ~1012 cm-2), observamos uma variação de Dit em função da concentração de nitrogênio no filme, esta variação porém é pequena comparada com a dispersão de duas ordens de grandeza observada, que atribuímos assim a fatores externos. O menor valor obtido de Dit foi de 4,55.1010 eV-1.cm-2, que é ótimo para um filme obtido por PECVD, sem nenhum tratamento térmico e melhor que os reportados na literatura para dielétricos obtidos por técnicas que utilizam altas temperaturas (LPCVD-800ºC e oxinitretação térmica – 1100ºC). Assim, podemos concluir que a técnica de PECVD é promissora para a obtenção de dielétricos a baixas temperaturas. / In this work, MOS capacitors with different chemical composition silicon oxynitride insulating layer, deposited by PECVD technique at low temperature were fabricated and characterized, in order to study its dielectric and interface properties, seeking its aplication as insulating layer in MOS and thin films devices. The MOS capacitors were fabricated onto p-silicion wafers previously cleaned by a standard process, followed by the insulating layer deposition, photolitography, metalization and sinterization. The SiOxNy insulating layer was deposited by the PECVD technique at 320ºC changing the precursor gases flows to obtain films with different chemical compositions. The MOS capacitors were characterized by capacitance and current vs. voltage measurements, from where the interface state density (Dit), the effective charge density (Nss), the dielectric constant (k) and the film electrical breakdown field (Ebd) were extracted. The results showed a dielectric constant varying linearly as a function of the films nitrogen concentration, going from a value of 3.9, corresponding to stoichiometric silicon dioxide (SiO2) to a value of 7.2, corresponding to stoichiometric silicon nitride film (Si3N4). We also observed that nitrogen is an efficient diffusion barrier against contaminants. However, a large dispersion, about two orders of magnitude, in the effective charge and in the interface state density was observed. On the other hand, controlling some variables so as to keep the Nss value constant (~1012 cm-2) we observed a Dit variation as a function of the film nitrogen concentration, this variation is small when compared with the observed dispersion of two orders of magnitude, thus attributed to external factors. The smallest obtained Dit was 4.55.1010 eV-1.cm-2, which is unexpected for a PECVD film without any anealing process and is better than the values reported in the literature for dielectrics obtained at high temperatures techniques (as LPCVD – 800ºC and thermal oxynitridation – 1100ºC). Therefore, we can conclude that the PECVD technique is promising for obtaining low temperature dielectrics.

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