Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6549. Adviser: Kyekyoon (Kevin) Kim. Includes bibliographical references (leaves 90-102) Available on microfilm from Pro Quest Information and Learning.

A challenging application space exists for high-aspect-ratio, high-fidelity dielectrics in micro-electro-mechanical system (MEMS), microelectronic, and photonic applications. Photosensitive polymers are widely used in these fields because they are relatively easy to process and pattern, and have good mechanical properties. Photosensitive polynorbornene (PNB)-based dielectrics have been shown to have high sensitivity, excellent photodefinition properties, and high mechanical strength making them suitable for MEMS, microelectronic packaging, and photonic applications. PNB-based dielectrics can be functionalized with epoxide, carboxylic acid, or fluorinated alcohol groups. Epoxy or carboxylic acid groups can be used to provide cross-linkable sites, resulting in improved chemical and thermal properties while fluorinated alcohol groups can provide solubility in aqueous base. The focus of this study has been on the epoxy-based cross-linking of ultraviolet and electron beam (e-beam) sensitive negative-tone PNB-based dielectrics. The impact of multifunctional epoxy-based additives on the cross-linking, photolithographic properties, and adhesion properties of the photosensitive PNB dielectric was investigated. High aspect ratio features of 13:1 (height:width) were produced in 40 µm thick films (a single coat) with straight side-wall profiles and high fidelity. Contrast values as high as 33.4 were obtained at doses below 15 mJ/cm2. To evaluate the polymer's suitability to MEMS and microelectronics applications, epoxy cross-linking reactions were studied as a function of processing condition through Fourier transform infrared spectroscopy (FTIR), nanoindentation, swelling and dielectric measurements. The fully cross-linked films had an elastic modulus of 2.9 GPa and hardness of 0.18 GPa which can improve the mechanical compliance of the packaging device. To explore the feasibility of the PNB dielectric as a highly sensitive e-beam resist for nano scale fabrication, the e-beam initiated reaction between PNB cross-linking sites and the multifunctional epoxy cross-linkers was investigated. In this study, the interaction of an e-beam with the PNB mixture and its compounds was investigated. The contrast, photodefinability, and e-beam activation of the components in the PNB formulations were studied. The PNB polymer had very high e-beam sensitivity and contrast. It was shown that the addition of a photoacid generator (PAG) to the polymer-epoxy mixture enhanced the contrast and sensitivity. Formulations with the additional cross-linker showed improved contrast, sensitivity, and substrate adhesion. 100 nm structures with 13.5 nm line edge roughness (LER) were fabricated. The influence of the developing time, the developer concentration, PEB, and film thickness on the contrast and sensitivity were studied. Structures with contrast values as high as approximately 8 were fabricated at doses as low as 0.38 µC/cm2. The acid-catalyzed epoxy ring opening reaction of the PNB dielectric was studied using FTIR spectroscopy. The photo and thermal acid generation initiated epoxy ring opening reactions and subsequent cross-linking of polymer. Additionally, polymer properties were characterized as a function of processing conditions for this polymer system. It was shown that thermal cure conditions have a substantial impact on the mechanical and electrical properties of the polymer. The rate and ultimate conversion of the epoxy ring opening reaction increased with increasing cure temperature, resulting in a higher degree of cross-linking at cure temperatures above 140°C. Degradation reactions occurred at temperatures above 160°C, indicating loss of epoxide cross-linking groups and linkages. These hypotheses were supported by electrical and mechanical property studies. It was shown that curing the PNB polymer at 160°C for 1 h after develop resulted in full epoxy ring opening and highest cross-link density. This sample showed lower dielectric constant (3.9), residual stress (20 MPa), and solvent swelling (3.1%). Variable frequency microwave (VFM) processing of the PNB dielectric was studied to investigate the rapid curing of the polymer at lower temperatures. The FTIR results showed that the microwave reaction rates were higher at each isothermal cure temperature compared to convective heating, indicating that the rapid VFM curing of PNB at low temperatures is feasible. The PNB film was fully cross-linked after 15 min VFM cure at the low temperature of 150˚C. The shortest time to fully cure the polymer was found to be 5 min at 160°C. Also, the feasibility of rapid VFM curing of PNB in air was studied. All samples VFM-cured (140˚C-180˚C) in air showed no signs of oxidation. The electrical and mechanical properties of VFM-cured films were characterized and compared with thermally cured films to determine the effectiveness of the VFM processing. VFM-cured samples showed higher degree of cross-linking than thermally-cured samples, which was congruent with the FTIR results. Improved or equivalent properties were obtained for VFM-cured samples at shorter cure cycles and lower cure temperatures compared to thermally-cured films. The PNB dielectric was also used as an overcoat material to make micro and nano fluidic channels. In this work, incorporation of advanced micro/nano fluidics with high-sensitivity photonic sensors was demonstrated. 500 nm to 50 µm channels were fabricated by thermal decomposition of epoxy-based PNB polymers. Microdisks with quality factors of over 106 were presented in complementary metal-xide-semiconductor (CMOS) compatible SiN on oxide technology. These ultra-high quality factor SiN resonators were demonstrated in the visible range for the first time. The fluidic structures were interfaced with photonics for index and florescence sensing. This study was a collaboration with Dr. Ehsan Shahhosseini from the Photonics Group at Georgia Tech.

Orientador: Marco Antonio Robert Alves / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-16T13:49:16Z (GMT). No. of bitstreams: 1 Danieli_CarlosLucianoDe_M.pdf: 1990598 bytes, checksum: 6745c93234cd7c2b42245ced236075ec (MD5) Previous issue date: 2010 / Resumo: Este trabalho de mestrado utilizou várias técnicas convencionais de microfabricação desenvolvidas nas indústrias de semicondutores e teve como objetivo fabricar microponteiras de silício com melhorias nas características geométricas e morfológicas, ou seja, microponteiras altas e com pequenos cones de abertura, relacionados ao aumento do fator de emissão de campo (?) e redução da rugosidade da superfície, relacionado à função trabalho do material (?), utilizando máscaras de DLC e plasma de SF6/O2 e SF6 puro. Além disso, este trabalho investigou minuciosamente a origem, composição e distribuição da camada residual que apareceu no topo das microponteiras através da técnica de microanálise MEV/EDS, uma vez que a ocorrência de camadas residuais nas superfícies das microponteiras não tem sido reportada na literatura e que elas influenciam nas características da superfície das mesmas (substâncias adsorvidas e rugosidade) e do substrato. Com esta análise, foi possível verificar que o aparecimento da camada residual está relacionado ao mecanismo de corrosão do plasma de SF6/O2 que foi utilizado, pois se acredita que a camada residual encontrada trata-se da camada de passivação SiOxFy, que independe do material utilizado como máscara e que apresenta enxofre adsorvido em toda amostra. A técnica de AFM foi utilizada para se estudar em alta resolução os efeitos do plasma de SF6/O2 na morfologia da superfície do substrato. Com isso, foi possível verificar a existência de uma relação linear entre a rugosidade e tempo de corrosão, para as condições de processo utilizadas / Abstract: At this work, several conventional microfabrication techniques developed in the semiconductor industry were used and aimed to make silicon microtips with improved geometrical and morphological characteristics, ie taller microtips and the aperture cones of the tip smaller, related to increased emission factor field (?) and reduced surface roughness, related to the material work function (?), using DLC masks and plasma SF6/O2 and pure SF6. In addition, this study investigated in detail, the origin, composition and distribution of residual layer that have appeared at the top of microtips, using the technique of microanalysis by SEM/EDS, since the occurrence of residual layers on the surfaces of microtips have been not reported in the literature and their influence the surface characteristics of microtips (adsorbed substances and roughness) and the substrate. With this analysis, it was observed that the occurrence of the residual layer is related to the corrosion mechanism of plasma SF6/O2 used, because it is believed that the residual layer is found from the SiOxFy passivation layer, which is independent of mask material, and has sulfur adsorbed on all sample surface. The AFM technique was used to study with high resolution the effects of plasma SF6/O2 in the morphology of the substrate. Thus it was possible to verify the existence of a linear relationship between roughness and the corrosion time for the process conditions used / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Orientadores: Peter Jurgen Tatsch, Stanislav A. Moshkalev / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T09:15:24Z (GMT). No. of bitstreams: 1 Nunes_AlcineiMoura_D.pdf: 5060090 bytes, checksum: 2e93ff0bc8213b48460167d7e4cbbcc3 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foram desenvolvidas cinco aplicações de processos de corrosão por plasmas frios (temperatura ambiente), utilizando reatores dos tipos RIE (Corrosão por Íon Reativo) e ICP (Plasma Acoplado Indutivamente): Afinamento de porta de transistor CMOS - métodos convencionais como fotogravação, com resolução maior que 2 ?m, e corrosão por plasma em um reator RIE com as misturas gasosas SF6/CF4/CHF3 e SF6/CF4/N2, foram utilizados na obtenção de estruturas submicrométricas. A pressão foi variada de 50 mTorr a 150 mTorr e a potência de 30 W a 85 W. Corrosão de estruturas GaAs e AlGaAs para aplicação em transistores HEMT - as corrosões foram realizadas em um reator RIE com misturas de gás contendo SiCl4/Ar para a corrosão e O2/SF6/Ar para processo de limpeza da câmara; Corrosão de corpo para fabricação de sensores de pressão - foi utilizado um reator ICP e plasma de mistura gasosa SF6/Ar; Corrosão profunda para separação de patilhas utilizando métodos convencionais - foi utilizado um reator ICP para corrosão profunda dos canais. As misturas gasosas foram SF6/Ar, com polarização do eletrodo inferior para corrosão de Si (silício), e O2/Ar para remoção de fotorresiste; Teste de resistência de máscaras de Ni-P, Ni-B e SiO2 em processos de corrosão profunda e do tipo Bosch - as máscaras foram testadas em um reator ICP com plasma de misturas gasosas SF6/Ar e C4/F8. Em cada uma das aplicações foi feito um estudo sobre seus principais requerimentos, a fim de se obter o melhor compromisso entre os parâmetros do processo de corrosão / Abstract: This thesis is based on etching processes applications in cold plasmas (room temperature) using RIE (Reactive Ion Etching) and ICP (Inductively Coupled Plasma), as reactors, applied to specific areas of microelectronics and MEMS devices in semiconductors industries and laboratories. Five applications are presented: Thinning gate CMOS Transistor - conventional methods such as photolithography with resolution greater than 2 ?m and RIE reactor with gaseous mixtures: SF6/CF4/CHF3 and SF6/CF4/N2 were used to obtain structures below 1 ?m; GaAs and AlGaAs structures etching for HEMT transistors application - RIE reactor and mixtures containing SiCl4/Ar for etching and O2/SF6/Ar for cleaning were used; Bulk etching for pressure sensors - ICP reactor and gas mixture SF6/Ar were used; Deep Si etching for die separating - ICP reactor and gas mixtures SF6/Ar with bias for channel etching and O2/Ar for photoresist removal were used; Ni-P, Ni-B and SiO2 masks testing in deep etching processes - ICP reactor and gas mixtures as SF6/Ar and C4/F8 were used. In each applications a study of its main requirements was made, to achieve a better commitment between the parameters of the etching process / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Indiana University-Purdue University Indianapolis (IUPUI) / This research proposes state-of-the-art multilevel converter topologies and their modulation strategies, the implementation of a conventional flying-capacitor converter topology up to four-level, and a new four-level flying-capacitor H-Bridge converter confi guration. The three phase version of this proposed four-level flying-capacitor H-Bridge converter is given as well in this study. The highlighted advantages of the proposed converter are as following: (1) the same blocking voltage for all switches employed in the con figuration, (2) no capacitor midpoint connection is needed, (3) reduced number of passive elements as compared to the conventional solution, (4) reduced total dc source value by comparison with the conventional topology. The proposed four-level capacitor-clamped H-Bridge converter can be utilized as a multilevel inverter application in an electri fied railway system, or in hybrid electric vehicles. In addition to the implementation of the proposed topology in this research, its experimental setup has been designed to validate the simulation results of the given converter topologies.