Low-dielectric (k) films are one of the performance drivers for continued scaling of integrated circuit devices. These films are needed in microelectronic device interconnects to lower power consumption and minimize cross talk between metal lines that "interconnect" transistors. Low-k materials currently in production for the 45 and 65 nm node are most often organosilicate glasses (OSG) with dielectric constants near 2.8 and nominal porosities of 8-10%. The next generation of low-k materials will require k values 2.6 and below for the 45 nm device generation and beyond. The continuous decrease in device dimensions in ultra large scale integrated (ULSI) circuits have brought about the replacement of the silicon dioxide interconnect dielectric (ILD), which has a dielectric constant (k) of approximately 4.1, with low dielectric constant materials. Lowering the dielectric constant reduces the propagation delays, RC constant (R = the resistance of the metal lines; C = the line capacitance), and metal cross-talk between wires. In order to reduce the RC constants, a number of low-k materials have been studied for use as intermetal dielectrics. The k values of these dielectric materials can be lowered by replacing oxide films with carbon-based polymer films, incorporating hydrocarbon functional groups into oxide films (SiOCH films), or introducing porogens in the film during processing to create pores. However, additional integration issues such as damage to these materials caused by plasma etch, plasma ash, and wet etch processes are yet to be overcome. This dissertation reports the effects of plasma, temperature and chemical reactions on low-k SiOCH films. Plasma ash processes have been known to cause hydrophobic films to lose their hydrophobic methyl groups, rendering them to be hydrophilic. This allows the films to readily absorb moisture. Supercritical carbon dioxide (SC-CO2) can be used to transport silylating agents, hexamethyldisilazane (HMDS) and diethoxy-dimethlysilane (DEDMS), to functionalize the damaged surfaces of the ash-damaged films. The thermal stability of the low-k films after SC-CO2 treatment is also discussed by performing in-situ heat treatments on the films. UV curing has been shown to reduce the amount of pores while showing only a limited change dielectric constant. This work goes on to describe the effect of UV curing on low-k films after exposing the films to supercritical carbon dioxide (CO2) in combination with tetramethylorthosilicate (TMOS).

A series of reactive phenylethynyl endcapped imide oligomers has been prepared in either fully cyclized or amic acid precursor form. Soluble oligomers have been synthesized with controlled molecular weights ranging from 2- to 12 Kg/mol. Molecular weight characterization was performed using SEC (size exclusion chromatography) and 13C-NMR, revealing good agreement between the theoretical and experimental (Mn) values. Crosslinked polyimides were obtained by solution or melt processing the oligomers into films and gradually heating in a programmed temperature manner up to the appropriate reaction temperature for the phenylethynyl groups, which is approximately 350-400°C. Thermal analysis of the resulting films showed high glass transition temperatures (>300°C) and excellent thermal stability, comparable to those found for thermoplastic control polyimides. The crosslinked films also had exceptional solvent resistance as evidenced by a high gel fraction (greater than or equal to 95%) following extraction in common solvents for several days. This was in contrast to the amorphous thermoplastic controls, which quickly dissolved upon immersion in solvents. The monomers used for synthesizing the polyimide oligomers were varied systematically within the series to study the influence of both molecular structure and molecular weight on the physical and film-forming properties. The incorporation of fluorinated monomers, such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), reduced water absorption and lowered the dielectric constant relative to non-fluorinated polyimides in the series. When flexible ether linkages were incorporated in the repeat unit by using 4,4'-oxydianiline (ODA), relatively more ductile solvent-cast films were obtained from oligomers having Mn values as low as 10 Kg/mol. Additionally, oligomer Mn and the relative rigidity/symmetry of the repeat unit structure greatly influenced the solubility of polyimides in NMP. For example, even 6FDA/p-phenylenediamine based oligomers with Mn values targeted below 10 Kg/mol precipitated from NMP at 180°C during solution imidization. The relationship between solution viscosities of polyimide and poly(amic acid) thermosetting oligomers and wetting/spreading ability to form continuous films during spin casting was elucidated. Employing o-dimethoxybenzene (DMB) as a cosolvent with NMP improved the film-forming ability of the fully imidized 6FDA/ODA oligomer series. This was evidenced by a decrease in viscosity (via suppression of physical-type gel formation) and better overall coverage and clarity of the films. Humidity was found to have a detrimental effect, causing the polyimide oligomers to phase separate to form cloudy or porous films. When moisture was reduced, oligomers having Mn greater than or equal to 6 Kg/mol formed spin cast films of <20 micrometer thickness with good qualitative adhesion to several inorganic substrates. Dielectric constants (epsilon) were estimated for several of the polyimides by measuring the refractive indices (n) of the films and using Maxwell's relationship (epsilon at optical frequencies is equal to n raised to the second power). The apparent dielectric constants were low, ranging from 2.47 to 2.75. The novel combination of low dielectric constant, solvent resistance and isotropic physical properties inherent in the thermosetting polyimide oligomers makes these materials excellent candidates for use as thin film insulating layers in microelectronics packaging applications. / Ph. D.

This study is an investigation of the chemical vapor deposition (CVD) of aluminum and copper on fluoropolymer surfaces and the subsequent interfacial interactions.

The incorporation of porosity in a material potentially results in the changes in electrical, mechanical and electrical properties and has generated much interest by researchers. The development of new techniques for inducing porosity in thin films may prove advantageous if they lead to a decrease in processing complexity, or an increase in the processing flexibility by widening the window of compatible physical conditions, or the improvement of the final properties of the porous materials. Two processing techniques were developed to produce porosity in thin dielectric films at temperatures below the glass transition temperature of the host matrix. These glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) to gelation in the glassy regime when exposed to polar substances. Both of these glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) towards gelation in the glassy regime when exposed to polar substances. The first processing method made use of co-solvent mixtures of polar non-protic organic solvent to serve both as gelation catalysts and pore-generators. HSQ films were soaked in the polar organic co-solvents, which penetrated the films and initiated crosslinking throughout the matrix. Afterwards the films were baked, volatilizing entrapped solvents and producing air pockets within the rigid matrix. The second porosity method used UV-radiation to initiate acid-catalyzed decomposition of polycarbonate sacrificial polymers after first using bases to catalyze the gelation of HSQ. The radiation-based (direct-write) decomposition of the porogen enabled the selective patterning of regions porosity via the use of a photomask, which resulted in the creation of refractive index profiles in the direct-written films. Porous films that were produced by these two glassy-state processing techniques were used to build slab waveguide structures. Optical characterization experiments showed that the fabricated waveguides had average propagation losses of 16 - 27 dB/cm for the first guided TE mode and about 36-40 dB/cm, for the second TE guided mode. It is believed that the large propagation loss values were caused by a combination of the Rayleigh scattering from the relatively large UV-induced pores produced in the direct-write layers as well as scattering induced by surface roughness.

In recent years, advanced high κ gate dielectrics are under serious consideration to replace SiO2 and SiON in semiconductor industry. Hafnium-based dielectrics such as hafnium oxides, oxynitrides and Hf-based silicates/nitrided silicates are emerging as some of the most promising alternatives to SiO2/SiON gate dielectrics in complementary metal oxide semiconductor (CMOS) devices. Extensive efforts have been taken to understand the effects of hydrogen impurities in semiconductors and its behavior such as incorporation, diffusion, trapping and release with the aim of controlling and using it to optimize the performance of electronic device structures. In this dissertation, a systematic study of hydrogen trapping and the role of carbon impurities in various alternate gate dielectric candidates, HfO2/Si, HfxSi1-xO2/Si, HfON/Si and HfON(C)/Si is presented. It has been shown that processing of high κ dielectrics may lead to some crystallization issues. Rutherford backscattering spectroscopy (RBS) for measuring oxygen deficiencies, elastic recoil detection analysis (ERDA) for quantifying hydrogen and nuclear reaction analysis (NRA) for quantifying carbon, X-ray diffraction (XRD) for measuring degree of crystallinity and X-ray photoelectron spectroscopy (XPS) were used to characterize these thin dielectric materials. ERDA data are used to characterize the evolution of hydrogen during annealing in hydrogen ambient in combination with preprocessing in oxygen and nitrogen.

The objective of the present dissertation is to advance the science and engineering of metal-dielectric thin-film structures for ultrafast all-optical applications. The research presented consists of three parts: first, the linear and nonlinear optical (NLO) properties of Au and Ag/Au bilayer metallic thin films are comprehensively studied; then the design and properties of a novel nonlinear device structure are presented and finally an ultrafast all-optical shutter is developed and applications are discussed. In the first part, this study describes the linear and NLO properties of bilayer metallic films and shows that they can be tuned by controlling the mass-thickness ratio between Au and Ag. The combined properties of these bilayers are attractive for active plasmonic applications and nonlinear optical filters. Detailed physical models describing the linear and NLO response of Au and Ag/Au bilayers are presented and compared with experiments. In the second part, these models are used to optimize the NLO response of a novel Au-based NLO device. With only four layers, this novel device strongly amplifies the NLO response of the component Au thin film. NLO devices with broad spectral and angular bandwidths in the visible spectral region are demonstrated. The narrow band dependent NLO response of the NLO device is shown to lead to all-optical controls of high peak-power optical signal pulses. Finally, the NLO device technology is integrated into a novel ultrafast all-optical shutter, which allows temporal opening windows (the time shutter remains open) as short as a few ps. Ultrafast all-optical shutter potentially can temporally shape high peak-power nanosecond optical pulses, which could benefit biomedical and micromachining applications. Other possible optical applications such as short electron, X-ray pulse generations, ultrafast photography, and biomedical imaging will also be discussed.

Studies of the radiative properties of thin films and near-field radiation transfer in layered structures are important for applications in energy, near-field imaging, coherent thermal emission, and aerospace thermal management. A comprehensive study is performed on the optical constants of dielectric tantalum pentoxide (Ta₂O₅) and hafnium oxide (HfO₂) thin films from visible to the far infrared using spectroscopic methods. These materials have broad applications in metallo-dielectric multilayers, anti-reflection coatings, and coherent emitters based on photonic crystal structures, especially at high temperatures since both materials have melting points above 2000 K. The dielectric functions of HfO₂ and Ta₂O₅ obtained from this work may facilitate future design of devices with these materials. A parametric study of near-field TPV performance using a backside reflecting mirror is also performed. Currently proposed near-field TPV devices have been shown to have increased power throughput compared to their far-field counterparts, but whose conversion efficiencies are lower than desired. This is due to their low quantum efficiency caused by recombination of minority carriers and the waste of sub-bandgap radiation. The efficiency may be improved by adding a gold mirror as well as by reducing the surface recombination velocity, as demonstrated in this thesis. The analysis of the near-field TPV and proposed methods may facilitate the development or high-efficiency energy harvesting devices. Many near-field devices may eventually utilize metallo-dielectric structures which exhibit unique properties such as negative refraction due to their hyperbolic isofrequency contour. These metamaterials are also called indefinite materials because of their ability to support propagating waves with large lateral wavevectors, which can result in enhanced near-field radiative heat transfer. The energy streamlines in such structures are studied for the first time. Energy streamlines illustrate the flow of energy through a structure when the fields are evanescent and energy propagation is not ray like. The energy streamlines through two semi-infinite uniaxially anisotropic effective medium structures, separated by a small vacuum gap, are modeled using the Green’s function. The lateral shift and penetration depth are calculated from the streamlines and shown to be relatively large compared to the vacuum gap dimension. The study of energy streamlines in hyperbolic metamaterials helps understand the near-field energy propagation on a fundamental level.

No presente trabalho, foram investigados os efeitos de tratamentos térmicos em vapor d’água, em óxido nítrico e em hidrogênio nas propriedades físico-químicas e elétricas de filmes dielétricos crescidos termicamente e/ou depositadas por sputtering sobre lâminas de carbeto de silício. A caracterização foi realizada antes e após tratamentos térmicos nesses ambientes através de técnicas que utilizam feixes de íons. Em alguns casos, a caracterização elétrica também foi realizada. A investigação da incorporação e distribuição em profundidade de hidrogênio e oxigênio após tratamentos de SiO2/SiC e SiO2/Si em vapor d’água mostrou que há diferenças marcantes na interação da água com as duas estruturas. Observou-se maior incorporação de oxigênio no filme pré-existente de SiO2 sobre o SiC do que em SiO2/Si, evidenciando uma maior concentração de defeitos nos filmes sobre SiC. A incorporação de hidrogênio também foi maior nas estruturas SiO2/SiC, sendo observada em todas as regiões do filme de SiO2 crescido sobre SiC. Nos filmes crescidos sobre Si, no entanto, a incorporação deuse, principalmente, na região da superfície do filme de óxido. A interação do vapor d’água com estruturas SiO2/SiC e SiO2/Si com filmes depositados por sputtering também foi investigada. Foi constatada uma incorporação distinta da observada para essas estruturas quando seus óxidos foram crescidos termicamente. A incorporação de hidrogênio do vapor d’água em estruturas com filmes de SiO2 depositados por sputtering sobre SiC e sobre Si ocorre, principalmente, na interface SiO2/substrato. A distribuição em profundidade de oxigênio após a exposição a vapor d'água a 800°C revelou que ele é incorporado em toda a espessura dos óxidos depositados sobre ambos os substratos, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes de óxido. O crescimento térmico antes da deposição de SiO2 sobre o SiC levou à incorporação de menores quantidades de hidrogênio, quando comparadas com as estruturas relativas a filmes apenas depositados. No entanto, à medida que o tempo de oxidação térmica foi aumentado, observou-se maior incorporação de hidrogênio, o que foi atribuído à formação de defeitos no filme de óxido susceptíveis à interação com o mesmo. O crescimento térmico por um tempo curto seguido pela deposição de SiO2 e o crescimento térmico não seguido de outro tratamento levaram a menores incorporações de D do que a deposição não seguida de outro tratamento, o que pode ser correlacionado com as melhores características elétricas observadas nessas estruturas. Outro tema abordado foi a incorporação de hidrogênio através de tratamento térmico em 2H2, com e sem a presença de um eletrodo de platina, em filmes dielétricos crescidos em atmosfera de O2, NO e via tratamento térmico sequencial nesses dois gases. Quando o crescimento térmico em O2 foi seguido de tratamento em NO, foi observada uma forte troca isotópica entre o oxigênio da fase gasosa e o oxigênio do filme de SiO2, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes. A incorporação de hidrogênio mostrou-se fortemente dependente da rota utilizada no crescimento do filme dielétrico. Sem a presença do eletrodo de platina, o crescimento do filme dielétrico direto em NO foi a rota que apresentou a maior incorporação de hidrogênio. A presença de platina, por sua vez, promoveu um aumento na incorporação de hidrogênio nos filmes dielétricos obtidos através das três rotas de crescimento. Em todos os casos, observou-se que a incorporação de hidrogênio ocorre, principalmente, na região da interface entre o filme dielétrico e o SiC. A incorporação de maiores quantidades de hidrogênio foi associada com a presença de N previamente incorporado. A atmosfera reativa utilizada no crescimento térmico dos filmes dielétricos também mostrou influência nas características elétricas das estruturas analisadas. A caracterização por curvas C-V mostrou um aumento no deslocamento da tensão de banda plana após tratamentos térmicos em 2H2, indicando o aumento e/ou formação de carga positiva. Por fim, a interação de vapor d'água em estruturas de SiO2/SiC e de SiO2/Si com filmes crescidos termicamente e tratadas em NO foi investigada. Observou-se que as estruturas SiO2/SiC que foram submetidas a tratamentos térmicos em NO apresentaram menor incorporação de hidrogênio, devido à exposição a vapor d'água. Esse efeito também foi observado em estruturas SiO2/SiC quando o pós-tratamento em NO foi substituído por um póstratamento em argônio na mesma temperatura e tempo, indicando que a temperatura de tratamento é a responsável pelas menores incorporações de hidrogênio, não a reatividade do gás empregado. / In the present work, effects of thermal treatments in water vapor, in nitric oxide, and in hydrogen in the physicochemical and in the electrical properties of dielectric films thermally grown and/or deposited by sputtering on silicon carbide were investigated. The characterization was performed using ion beam analyses before and after thermal treatments in these atmospheres. In some cases, the electrical characterization was also performed. The investigation of the incorporation and depth distribution of hydrogen and oxygen after annealing of SiO2/SiC and SiO2/Si in water vapor evidenced that there are striking differences regarding water interaction with these two structures. It was observed larger oxygen incorporation in the pre-existent SiO2 film on SiC than in the SiO2/Si, which evidences higher concentration of defects in oxide films on SiC. The incorporation of hydrogen was also larger in SiO2/SiC structures, being observed in all regions of the dielectric film. In oxide films grown on Si, however, the incorporation occurred mainly in the surface region of the oxide. The interaction of water vapor with SiO2/SiC and SiO2/Si structures, whose films were deposited by sputtering, was also investigated. A distinct incorporation was observed when comparing results from structures whose oxides were thermally grown. The incorporation of hydrogen from water vapor in structures in which SiO2 films were deposited by sputtering on SiC and on Si, occurred mainly in the SiO2/substrate interface. The oxygen depth distribution after exposure to water vapor at 800°C revealed that it was incorporated in all depths of the oxides that were deposited on both substrates, evidencing the high mobility of oxygen atoms in these oxide films. The thermal growth prior to SiO2 deposition on SiC led to the incorporation of smaller amounts of hydrogen, compared with structures with films that were only deposited. Nevertheless, as the thermal oxidation time increases, a larger incorporation of hydrogen was observed, which was attributed to the formation of defects in the oxide film that are more likely to interact with hydrogen. The thermal growth for short time followed by the deposition of SiO2 and the thermal growth not followed by any other treatment led to lower amounts of hydrogen, when compared with the deposition not followed by another treatment, which can be correlated with the improvement in the electrical characteristics observed in these structures. Another subject investigated was the incorporation of hydrogen by 2H2 anneal, with and without the presence of platinum, in dielectric films thermally grown in O2, NO, and in sequential thermal treatments in these two atmospheres. In the case of thermal growth in O2 followed by NO anneal, it was observed a notable isotopic exchange between oxygen from the gas phase and oxygen from the SiO2 film, evidencing that oxygen atoms are highly mobile in these films. The incorporation of hydrogen was showed to be highly dependent on the route employed in the dielectric film growth, being the direct growth of dielectric films in NO the one that presented larger incorporation without the presence of Pt electrode. The presence of this metal increases the incorporation of hydrogen in all dielectric films. In all cases, it was observed that the incorporation of hydrogen occurred mainly in the interface region between the dielectric film and the SiC. The incorporation of larger amounts of hydrogen was associated with the presence of N that was previously incorporated. The reactive atmosphere employed in the thermal growth of dielectric films also was observed to affect electrical characteristics in analyzed structures. The characterization by C-V measurements evidenced an increase in the flatband voltage shift after annealing in 2H2, indicating the increase and/or the formation of positive charge. Finally, the interaction of water vapor in SiO2/SiC and SiO2/Si structures with dielectric films thermally grown and annealed in NO was investigated. It was observed that SiO2/SiC structures that were submitted to NO anneal presented less hydrogen incorporation due to exposure to water vapor. This behavior was also observed in SiO2/SiC structures when the NO anneal was replaced by an annealing in Ar at the same temperature and time, indicating that the temperature of the annealing was responsible by the less incorporation of hydrogen instead of the reactivity of the gas employed.

No presente trabalho, foram investigados os efeitos de tratamentos térmicos em vapor d’água, em óxido nítrico e em hidrogênio nas propriedades físico-químicas e elétricas de filmes dielétricos crescidos termicamente e/ou depositadas por sputtering sobre lâminas de carbeto de silício. A caracterização foi realizada antes e após tratamentos térmicos nesses ambientes através de técnicas que utilizam feixes de íons. Em alguns casos, a caracterização elétrica também foi realizada. A investigação da incorporação e distribuição em profundidade de hidrogênio e oxigênio após tratamentos de SiO2/SiC e SiO2/Si em vapor d’água mostrou que há diferenças marcantes na interação da água com as duas estruturas. Observou-se maior incorporação de oxigênio no filme pré-existente de SiO2 sobre o SiC do que em SiO2/Si, evidenciando uma maior concentração de defeitos nos filmes sobre SiC. A incorporação de hidrogênio também foi maior nas estruturas SiO2/SiC, sendo observada em todas as regiões do filme de SiO2 crescido sobre SiC. Nos filmes crescidos sobre Si, no entanto, a incorporação deuse, principalmente, na região da superfície do filme de óxido. A interação do vapor d’água com estruturas SiO2/SiC e SiO2/Si com filmes depositados por sputtering também foi investigada. Foi constatada uma incorporação distinta da observada para essas estruturas quando seus óxidos foram crescidos termicamente. A incorporação de hidrogênio do vapor d’água em estruturas com filmes de SiO2 depositados por sputtering sobre SiC e sobre Si ocorre, principalmente, na interface SiO2/substrato. A distribuição em profundidade de oxigênio após a exposição a vapor d'água a 800°C revelou que ele é incorporado em toda a espessura dos óxidos depositados sobre ambos os substratos, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes de óxido. O crescimento térmico antes da deposição de SiO2 sobre o SiC levou à incorporação de menores quantidades de hidrogênio, quando comparadas com as estruturas relativas a filmes apenas depositados. No entanto, à medida que o tempo de oxidação térmica foi aumentado, observou-se maior incorporação de hidrogênio, o que foi atribuído à formação de defeitos no filme de óxido susceptíveis à interação com o mesmo. O crescimento térmico por um tempo curto seguido pela deposição de SiO2 e o crescimento térmico não seguido de outro tratamento levaram a menores incorporações de D do que a deposição não seguida de outro tratamento, o que pode ser correlacionado com as melhores características elétricas observadas nessas estruturas. Outro tema abordado foi a incorporação de hidrogênio através de tratamento térmico em 2H2, com e sem a presença de um eletrodo de platina, em filmes dielétricos crescidos em atmosfera de O2, NO e via tratamento térmico sequencial nesses dois gases. Quando o crescimento térmico em O2 foi seguido de tratamento em NO, foi observada uma forte troca isotópica entre o oxigênio da fase gasosa e o oxigênio do filme de SiO2, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes. A incorporação de hidrogênio mostrou-se fortemente dependente da rota utilizada no crescimento do filme dielétrico. Sem a presença do eletrodo de platina, o crescimento do filme dielétrico direto em NO foi a rota que apresentou a maior incorporação de hidrogênio. A presença de platina, por sua vez, promoveu um aumento na incorporação de hidrogênio nos filmes dielétricos obtidos através das três rotas de crescimento. Em todos os casos, observou-se que a incorporação de hidrogênio ocorre, principalmente, na região da interface entre o filme dielétrico e o SiC. A incorporação de maiores quantidades de hidrogênio foi associada com a presença de N previamente incorporado. A atmosfera reativa utilizada no crescimento térmico dos filmes dielétricos também mostrou influência nas características elétricas das estruturas analisadas. A caracterização por curvas C-V mostrou um aumento no deslocamento da tensão de banda plana após tratamentos térmicos em 2H2, indicando o aumento e/ou formação de carga positiva. Por fim, a interação de vapor d'água em estruturas de SiO2/SiC e de SiO2/Si com filmes crescidos termicamente e tratadas em NO foi investigada. Observou-se que as estruturas SiO2/SiC que foram submetidas a tratamentos térmicos em NO apresentaram menor incorporação de hidrogênio, devido à exposição a vapor d'água. Esse efeito também foi observado em estruturas SiO2/SiC quando o pós-tratamento em NO foi substituído por um póstratamento em argônio na mesma temperatura e tempo, indicando que a temperatura de tratamento é a responsável pelas menores incorporações de hidrogênio, não a reatividade do gás empregado. / In the present work, effects of thermal treatments in water vapor, in nitric oxide, and in hydrogen in the physicochemical and in the electrical properties of dielectric films thermally grown and/or deposited by sputtering on silicon carbide were investigated. The characterization was performed using ion beam analyses before and after thermal treatments in these atmospheres. In some cases, the electrical characterization was also performed. The investigation of the incorporation and depth distribution of hydrogen and oxygen after annealing of SiO2/SiC and SiO2/Si in water vapor evidenced that there are striking differences regarding water interaction with these two structures. It was observed larger oxygen incorporation in the pre-existent SiO2 film on SiC than in the SiO2/Si, which evidences higher concentration of defects in oxide films on SiC. The incorporation of hydrogen was also larger in SiO2/SiC structures, being observed in all regions of the dielectric film. In oxide films grown on Si, however, the incorporation occurred mainly in the surface region of the oxide. The interaction of water vapor with SiO2/SiC and SiO2/Si structures, whose films were deposited by sputtering, was also investigated. A distinct incorporation was observed when comparing results from structures whose oxides were thermally grown. The incorporation of hydrogen from water vapor in structures in which SiO2 films were deposited by sputtering on SiC and on Si, occurred mainly in the SiO2/substrate interface. The oxygen depth distribution after exposure to water vapor at 800°C revealed that it was incorporated in all depths of the oxides that were deposited on both substrates, evidencing the high mobility of oxygen atoms in these oxide films. The thermal growth prior to SiO2 deposition on SiC led to the incorporation of smaller amounts of hydrogen, compared with structures with films that were only deposited. Nevertheless, as the thermal oxidation time increases, a larger incorporation of hydrogen was observed, which was attributed to the formation of defects in the oxide film that are more likely to interact with hydrogen. The thermal growth for short time followed by the deposition of SiO2 and the thermal growth not followed by any other treatment led to lower amounts of hydrogen, when compared with the deposition not followed by another treatment, which can be correlated with the improvement in the electrical characteristics observed in these structures. Another subject investigated was the incorporation of hydrogen by 2H2 anneal, with and without the presence of platinum, in dielectric films thermally grown in O2, NO, and in sequential thermal treatments in these two atmospheres. In the case of thermal growth in O2 followed by NO anneal, it was observed a notable isotopic exchange between oxygen from the gas phase and oxygen from the SiO2 film, evidencing that oxygen atoms are highly mobile in these films. The incorporation of hydrogen was showed to be highly dependent on the route employed in the dielectric film growth, being the direct growth of dielectric films in NO the one that presented larger incorporation without the presence of Pt electrode. The presence of this metal increases the incorporation of hydrogen in all dielectric films. In all cases, it was observed that the incorporation of hydrogen occurred mainly in the interface region between the dielectric film and the SiC. The incorporation of larger amounts of hydrogen was associated with the presence of N that was previously incorporated. The reactive atmosphere employed in the thermal growth of dielectric films also was observed to affect electrical characteristics in analyzed structures. The characterization by C-V measurements evidenced an increase in the flatband voltage shift after annealing in 2H2, indicating the increase and/or the formation of positive charge. Finally, the interaction of water vapor in SiO2/SiC and SiO2/Si structures with dielectric films thermally grown and annealed in NO was investigated. It was observed that SiO2/SiC structures that were submitted to NO anneal presented less hydrogen incorporation due to exposure to water vapor. This behavior was also observed in SiO2/SiC structures when the NO anneal was replaced by an annealing in Ar at the same temperature and time, indicating that the temperature of the annealing was responsible by the less incorporation of hydrogen instead of the reactivity of the gas employed.

No presente trabalho, foram investigados os efeitos de tratamentos térmicos em vapor d’água, em óxido nítrico e em hidrogênio nas propriedades físico-químicas e elétricas de filmes dielétricos crescidos termicamente e/ou depositadas por sputtering sobre lâminas de carbeto de silício. A caracterização foi realizada antes e após tratamentos térmicos nesses ambientes através de técnicas que utilizam feixes de íons. Em alguns casos, a caracterização elétrica também foi realizada. A investigação da incorporação e distribuição em profundidade de hidrogênio e oxigênio após tratamentos de SiO2/SiC e SiO2/Si em vapor d’água mostrou que há diferenças marcantes na interação da água com as duas estruturas. Observou-se maior incorporação de oxigênio no filme pré-existente de SiO2 sobre o SiC do que em SiO2/Si, evidenciando uma maior concentração de defeitos nos filmes sobre SiC. A incorporação de hidrogênio também foi maior nas estruturas SiO2/SiC, sendo observada em todas as regiões do filme de SiO2 crescido sobre SiC. Nos filmes crescidos sobre Si, no entanto, a incorporação deuse, principalmente, na região da superfície do filme de óxido. A interação do vapor d’água com estruturas SiO2/SiC e SiO2/Si com filmes depositados por sputtering também foi investigada. Foi constatada uma incorporação distinta da observada para essas estruturas quando seus óxidos foram crescidos termicamente. A incorporação de hidrogênio do vapor d’água em estruturas com filmes de SiO2 depositados por sputtering sobre SiC e sobre Si ocorre, principalmente, na interface SiO2/substrato. A distribuição em profundidade de oxigênio após a exposição a vapor d'água a 800°C revelou que ele é incorporado em toda a espessura dos óxidos depositados sobre ambos os substratos, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes de óxido. O crescimento térmico antes da deposição de SiO2 sobre o SiC levou à incorporação de menores quantidades de hidrogênio, quando comparadas com as estruturas relativas a filmes apenas depositados. No entanto, à medida que o tempo de oxidação térmica foi aumentado, observou-se maior incorporação de hidrogênio, o que foi atribuído à formação de defeitos no filme de óxido susceptíveis à interação com o mesmo. O crescimento térmico por um tempo curto seguido pela deposição de SiO2 e o crescimento térmico não seguido de outro tratamento levaram a menores incorporações de D do que a deposição não seguida de outro tratamento, o que pode ser correlacionado com as melhores características elétricas observadas nessas estruturas. Outro tema abordado foi a incorporação de hidrogênio através de tratamento térmico em 2H2, com e sem a presença de um eletrodo de platina, em filmes dielétricos crescidos em atmosfera de O2, NO e via tratamento térmico sequencial nesses dois gases. Quando o crescimento térmico em O2 foi seguido de tratamento em NO, foi observada uma forte troca isotópica entre o oxigênio da fase gasosa e o oxigênio do filme de SiO2, evidenciando a alta mobilidade dos átomos de oxigênio nesses filmes. A incorporação de hidrogênio mostrou-se fortemente dependente da rota utilizada no crescimento do filme dielétrico. Sem a presença do eletrodo de platina, o crescimento do filme dielétrico direto em NO foi a rota que apresentou a maior incorporação de hidrogênio. A presença de platina, por sua vez, promoveu um aumento na incorporação de hidrogênio nos filmes dielétricos obtidos através das três rotas de crescimento. Em todos os casos, observou-se que a incorporação de hidrogênio ocorre, principalmente, na região da interface entre o filme dielétrico e o SiC. A incorporação de maiores quantidades de hidrogênio foi associada com a presença de N previamente incorporado. A atmosfera reativa utilizada no crescimento térmico dos filmes dielétricos também mostrou influência nas características elétricas das estruturas analisadas. A caracterização por curvas C-V mostrou um aumento no deslocamento da tensão de banda plana após tratamentos térmicos em 2H2, indicando o aumento e/ou formação de carga positiva. Por fim, a interação de vapor d'água em estruturas de SiO2/SiC e de SiO2/Si com filmes crescidos termicamente e tratadas em NO foi investigada. Observou-se que as estruturas SiO2/SiC que foram submetidas a tratamentos térmicos em NO apresentaram menor incorporação de hidrogênio, devido à exposição a vapor d'água. Esse efeito também foi observado em estruturas SiO2/SiC quando o pós-tratamento em NO foi substituído por um póstratamento em argônio na mesma temperatura e tempo, indicando que a temperatura de tratamento é a responsável pelas menores incorporações de hidrogênio, não a reatividade do gás empregado. / In the present work, effects of thermal treatments in water vapor, in nitric oxide, and in hydrogen in the physicochemical and in the electrical properties of dielectric films thermally grown and/or deposited by sputtering on silicon carbide were investigated. The characterization was performed using ion beam analyses before and after thermal treatments in these atmospheres. In some cases, the electrical characterization was also performed. The investigation of the incorporation and depth distribution of hydrogen and oxygen after annealing of SiO2/SiC and SiO2/Si in water vapor evidenced that there are striking differences regarding water interaction with these two structures. It was observed larger oxygen incorporation in the pre-existent SiO2 film on SiC than in the SiO2/Si, which evidences higher concentration of defects in oxide films on SiC. The incorporation of hydrogen was also larger in SiO2/SiC structures, being observed in all regions of the dielectric film. In oxide films grown on Si, however, the incorporation occurred mainly in the surface region of the oxide. The interaction of water vapor with SiO2/SiC and SiO2/Si structures, whose films were deposited by sputtering, was also investigated. A distinct incorporation was observed when comparing results from structures whose oxides were thermally grown. The incorporation of hydrogen from water vapor in structures in which SiO2 films were deposited by sputtering on SiC and on Si, occurred mainly in the SiO2/substrate interface. The oxygen depth distribution after exposure to water vapor at 800°C revealed that it was incorporated in all depths of the oxides that were deposited on both substrates, evidencing the high mobility of oxygen atoms in these oxide films. The thermal growth prior to SiO2 deposition on SiC led to the incorporation of smaller amounts of hydrogen, compared with structures with films that were only deposited. Nevertheless, as the thermal oxidation time increases, a larger incorporation of hydrogen was observed, which was attributed to the formation of defects in the oxide film that are more likely to interact with hydrogen. The thermal growth for short time followed by the deposition of SiO2 and the thermal growth not followed by any other treatment led to lower amounts of hydrogen, when compared with the deposition not followed by another treatment, which can be correlated with the improvement in the electrical characteristics observed in these structures. Another subject investigated was the incorporation of hydrogen by 2H2 anneal, with and without the presence of platinum, in dielectric films thermally grown in O2, NO, and in sequential thermal treatments in these two atmospheres. In the case of thermal growth in O2 followed by NO anneal, it was observed a notable isotopic exchange between oxygen from the gas phase and oxygen from the SiO2 film, evidencing that oxygen atoms are highly mobile in these films. The incorporation of hydrogen was showed to be highly dependent on the route employed in the dielectric film growth, being the direct growth of dielectric films in NO the one that presented larger incorporation without the presence of Pt electrode. The presence of this metal increases the incorporation of hydrogen in all dielectric films. In all cases, it was observed that the incorporation of hydrogen occurred mainly in the interface region between the dielectric film and the SiC. The incorporation of larger amounts of hydrogen was associated with the presence of N that was previously incorporated. The reactive atmosphere employed in the thermal growth of dielectric films also was observed to affect electrical characteristics in analyzed structures. The characterization by C-V measurements evidenced an increase in the flatband voltage shift after annealing in 2H2, indicating the increase and/or the formation of positive charge. Finally, the interaction of water vapor in SiO2/SiC and SiO2/Si structures with dielectric films thermally grown and annealed in NO was investigated. It was observed that SiO2/SiC structures that were submitted to NO anneal presented less hydrogen incorporation due to exposure to water vapor. This behavior was also observed in SiO2/SiC structures when the NO anneal was replaced by an annealing in Ar at the same temperature and time, indicating that the temperature of the annealing was responsible by the less incorporation of hydrogen instead of the reactivity of the gas employed.