Este trabalho apresenta um método desenvolvido pela autora para, através de simulações multifísicas pelo Método dos Elementos Finitos (MEF), servir como ferramenta de apoio ao projeto e fabricação de guias de onda e moduladores eletro-ópticos em óptica integrada, além de possibilitar a análise da performance de moduladores eletro-ópticos. A técnica adotada para a fabricação dos guias de onda ópticos foi a de tensão mecânica. Os parâmetros de geometria (espessura do filme e larguras das trincheiras) e de temperatura de deposição do filme são definidos nas simulações e utilizados no processo de fabricação de guias de ondas em óptica integrada, que servem de base para a fabricação de moduladores eletro-ópticos em substrato cristalino de retículo cúbico. As trincheiras dos guias de onda do tipo canal são construídas em Germanato de Bismuto (BGO - Bi4Ge3O12), a partir da deposição sobre o substrato de um filme fino indutor de tensão mecânica (stress) Nitreto de Silício (Si3N4) e definidas pelos processos de litografia óptica e corrosão seletiva por plasma. Os moduladores são obtidos através da deposição dos eletrodos de alumínio sobre o filme, seguida de Si3N4 dos processos de litografia óptica e corrosão, obtendo-se eletrodos. O processo iterativo proposto inicia-se com os resultados das simulações, em que são definidos os parâmetros de fabricação do filme, da trincheira e dos eletrodos. Após a fabricação desses elementos, o componente é caracterizado e são medidos os parâmetros reais filme e do substrato. Esses valores são realimentados nas simulações para refinar o projeto do componente. O trabalho, além de apresentar todos os passos do processo interativo de simulações, projeto, fabricação e caracterização do componente desejado, indica as dificuldades encontradas na implementação do processo e as atividades futuras a serem desenvolvidas para o aperfeiçoamento do mesmo. / This work presents a method developed by the author to support the project and fabrication of integrated optic waveguides and electro-optic modulators by means of Finite Element Method (FEM) multiphysics simulations, also enabling the electro-optic modulators performance analysis. The technique used for fabricating the optical waveguides was the thermally induced residual stress (ISS). The geometry parameters (film thicknesses and trenches widths) and the film deposition temperature are obtained in the simulations and subsequently used in the integrated optical waveguides fabrication process, which serve as a basic building block for the electrooptic modulators on crystalline cubic lattice substrate. The channel waveguide trenches are built on Bismuth Germanate (BGO Bi4Ge3O12) by depositing a Silicon Nitride (Si3N4) Stress-inducing thin film, being later defined by optical lithography and plasma etching process. Modulators are obtained depositing aluminum on the Si3N4 film followed by the optical lithography and corrosion process, defining electrodes. The proposed iterative process starts with the simulation results that define the fabrication parameters of the film, trench and electrodes. After the fabrication of these elements, the device is characterized and the actual parameters of the film and substrate are measured. These values are fed back into the simulations to refine the component design. The work besides presenting all the simulation-design-fabrication-characterization iterative process for obtaining the devised device also highlights the difficulties encountered in the implementation process along with suggestions of future activities aiming at improving it.

The present work is dedicated to the development of high performance integrated circuits for wireless communications, by acting of three different levels: technologies, devices, and circuits. Silicon-on-Insulator (SOI) CMOS technology is used in the frame of this work. Micromachining technologies are also investigated for the fabrication of three-dimensional tunable capacitors. The reliability of micromachined thin-film devices is improved by the coating of silanes in both liquid- and vapor-phases. Since in telecommunication applications, distortion is responsible for the generation of spurious frequency bands, the linearity behavior of different SOI transistors is analyzed. The validity range of the existing low-frequency nonlinear characterization methods is discussed. New simple techniques valid at both low- and high-frequencies, are provided, based on the integral function method and on the Volterra series. Finally, the design of a crucial nonlinear circuit, the voltage-controlled oscillator, is introduced. The describing function formalism is used to evaluate the oscillation amplitude and is embedded in a design methodology. The frequency tuning by SOI varactors is analyzed in both small- and large-signal regimes.

Switching of surface composition and morphology of binary polymer brushes in response to changes in solvent selectivity, heating above glass transition temperatures, and contact with a rubbery stamp was studied. The binary brushes: polystyrene/poly(2-vinyl pyridine) (PS/P2VP), poly(styrene-co-2,3,4,5,6-pentafluorostyrene)/poly(methyl (meth)acrylate) (PSF/P(M)MA), and PS/PMMA were synthesized via two-step surface-initiated radical polymerization. Wetting experiments show that switching of brushes? surface composition upon exposure to solvents of various thermodynamic quality occurs faster than in 6 s. It takes longer time (5-10 min), if rate of solvent diffusion into the brush film is low. Discontinuous switching of surface composition of binary brushes is found upon exposure to binary solvents with gradually changed selectivity. X-ray Photoelectron Spectroscopy (XPS) shows quantitatively that the top brush layer (1) is dominated by respective favourite polymers after exposure to solvents of opposite selectivity and (2) comprises both brush constituents in almost symmetric ratio after exposure to non-selective solvents. Morphologies of binary brushes obtained after exposure to the solvents were studied with Atomic Force Microscopy (AFM). Local top layer composition was sensed with X-ray Photoemission Electron Microscopy (XPEEM). The morphologies are relevant to the particular solvents, reproducible, and independent on previous solvents. Phase segregation beneath the brush top layers was visualized with plasma etching. Qualitative agreement of the experimentally observed morphologies and predicted with self-consistent field theory is found. Enrichment of a binary brush top layer with the polymer providing lower surface energy takes place after annealing. Perpendicular segregation of binary brush constituents was sensed with XPEEM on perpendicular walls of imprinted elevations after wet microcontact printing.

Este trabalho apresenta um método desenvolvido pela autora para, através de simulações multifísicas pelo Método dos Elementos Finitos (MEF), servir como ferramenta de apoio ao projeto e fabricação de guias de onda e moduladores eletro-ópticos em óptica integrada, além de possibilitar a análise da performance de moduladores eletro-ópticos. A técnica adotada para a fabricação dos guias de onda ópticos foi a de tensão mecânica. Os parâmetros de geometria (espessura do filme e larguras das trincheiras) e de temperatura de deposição do filme são definidos nas simulações e utilizados no processo de fabricação de guias de ondas em óptica integrada, que servem de base para a fabricação de moduladores eletro-ópticos em substrato cristalino de retículo cúbico. As trincheiras dos guias de onda do tipo canal são construídas em Germanato de Bismuto (BGO - Bi4Ge3O12), a partir da deposição sobre o substrato de um filme fino indutor de tensão mecânica (stress) Nitreto de Silício (Si3N4) e definidas pelos processos de litografia óptica e corrosão seletiva por plasma. Os moduladores são obtidos através da deposição dos eletrodos de alumínio sobre o filme, seguida de Si3N4 dos processos de litografia óptica e corrosão, obtendo-se eletrodos. O processo iterativo proposto inicia-se com os resultados das simulações, em que são definidos os parâmetros de fabricação do filme, da trincheira e dos eletrodos. Após a fabricação desses elementos, o componente é caracterizado e são medidos os parâmetros reais filme e do substrato. Esses valores são realimentados nas simulações para refinar o projeto do componente. O trabalho, além de apresentar todos os passos do processo interativo de simulações, projeto, fabricação e caracterização do componente desejado, indica as dificuldades encontradas na implementação do processo e as atividades futuras a serem desenvolvidas para o aperfeiçoamento do mesmo. / This work presents a method developed by the author to support the project and fabrication of integrated optic waveguides and electro-optic modulators by means of Finite Element Method (FEM) multiphysics simulations, also enabling the electro-optic modulators performance analysis. The technique used for fabricating the optical waveguides was the thermally induced residual stress (ISS). The geometry parameters (film thicknesses and trenches widths) and the film deposition temperature are obtained in the simulations and subsequently used in the integrated optical waveguides fabrication process, which serve as a basic building block for the electrooptic modulators on crystalline cubic lattice substrate. The channel waveguide trenches are built on Bismuth Germanate (BGO Bi4Ge3O12) by depositing a Silicon Nitride (Si3N4) Stress-inducing thin film, being later defined by optical lithography and plasma etching process. Modulators are obtained depositing aluminum on the Si3N4 film followed by the optical lithography and corrosion process, defining electrodes. The proposed iterative process starts with the simulation results that define the fabrication parameters of the film, trench and electrodes. After the fabrication of these elements, the device is characterized and the actual parameters of the film and substrate are measured. These values are fed back into the simulations to refine the component design. The work besides presenting all the simulation-design-fabrication-characterization iterative process for obtaining the devised device also highlights the difficulties encountered in the implementation process along with suggestions of future activities aiming at improving it.

Switching of surface composition and morphology of binary polymer brushes in response to changes in solvent selectivity, heating above glass transition temperatures, and contact with a rubbery stamp was studied. The binary brushes: polystyrene/poly(2-vinyl pyridine) (PS/P2VP), poly(styrene-co-2,3,4,5,6-pentafluorostyrene)/poly(methyl (meth)acrylate) (PSF/P(M)MA), and PS/PMMA were synthesized via two-step surface-initiated radical polymerization. Wetting experiments show that switching of brushes? surface composition upon exposure to solvents of various thermodynamic quality occurs faster than in 6 s. It takes longer time (5-10 min), if rate of solvent diffusion into the brush film is low. Discontinuous switching of surface composition of binary brushes is found upon exposure to binary solvents with gradually changed selectivity. X-ray Photoelectron Spectroscopy (XPS) shows quantitatively that the top brush layer (1) is dominated by respective favourite polymers after exposure to solvents of opposite selectivity and (2) comprises both brush constituents in almost symmetric ratio after exposure to non-selective solvents. Morphologies of binary brushes obtained after exposure to the solvents were studied with Atomic Force Microscopy (AFM). Local top layer composition was sensed with X-ray Photoemission Electron Microscopy (XPEEM). The morphologies are relevant to the particular solvents, reproducible, and independent on previous solvents. Phase segregation beneath the brush top layers was visualized with plasma etching. Qualitative agreement of the experimentally observed morphologies and predicted with self-consistent field theory is found. Enrichment of a binary brush top layer with the polymer providing lower surface energy takes place after annealing. Perpendicular segregation of binary brush constituents was sensed with XPEEM on perpendicular walls of imprinted elevations after wet microcontact printing.