This thesis examines strategies to exploit existing materials and techniques to advance organic thin film transistor (OTFT) technology in device performance, device manufacture, and device integration. To enhance device performance, optimization of plasma enhanced chemical vapor deposited (PECVD) gate dielectric thin film and investigation of interface engineering methodologies are explored. To advance device manufacture, OTFT fabrication strategies are developed to enable organic circuit integration. Progress in device integration is achieved through demonstration of OTFT integration into functional circuits for applications such as active-matrix displays and radio frequency identification (RFID) tags. OTFT integration schemes featuring a tailored OTFT-compatible photolithography process and a hybrid photolithography-inkjet printing process are developed. They enable the fabrication of fully-patterned and fully-encapsulated OTFTs and circuits. Research on improving device performance of bottom-gate bottom-contact poly(3,3'''-dialkyl-quarter-thiophene) (PQT-12) OTFTs on PECVD silicon nitride (SiNx) gate dielectric leads to the following key conclusions: (a) increasing silicon content in SiNx gate dielectric leads to enhancement in field-effect mobility and on/off current ratio; (b) surface treatment of SiNx gate dielectric with a combination of O2 plasma and octyltrichlorosilane (OTS) self-assembled monolayer (SAM) delivers the best OTFT performance; (c) an optimal O2 plasma treatment duration exists for attaining highest field-effect mobility and is linked to a “turn-around” effect; and (d) surface treatment of the gold (Au) source/drain contacts by 1-octanethiol SAM limits mobility and should be omitted. There is a strong correlation between the electrical characteristics and the interfacial characteristics of OTFTs. In particular, the device mobility is influenced by the interplay of various interfacial mechanisms, including surface energy, surface roughness, and chemical composition. Finally, the collective knowledge from these investigations facilitates the integration of OTFTs into organic circuits, which is expected to contribute to the development of new generation of all-organic displays for communication devices and other pertinent applications. A major outcome of this work is that it provides an economical means for organic transistor and circuit integration, by enabling use of the well-established PECVD infrastructure, yet not compromising the performance of electronics.

This thesis examines strategies to exploit existing materials and techniques to advance organic thin film transistor (OTFT) technology in device performance, device manufacture, and device integration. To enhance device performance, optimization of plasma enhanced chemical vapor deposited (PECVD) gate dielectric thin film and investigation of interface engineering methodologies are explored. To advance device manufacture, OTFT fabrication strategies are developed to enable organic circuit integration. Progress in device integration is achieved through demonstration of OTFT integration into functional circuits for applications such as active-matrix displays and radio frequency identification (RFID) tags. OTFT integration schemes featuring a tailored OTFT-compatible photolithography process and a hybrid photolithography-inkjet printing process are developed. They enable the fabrication of fully-patterned and fully-encapsulated OTFTs and circuits. Research on improving device performance of bottom-gate bottom-contact poly(3,3'''-dialkyl-quarter-thiophene) (PQT-12) OTFTs on PECVD silicon nitride (SiNx) gate dielectric leads to the following key conclusions: (a) increasing silicon content in SiNx gate dielectric leads to enhancement in field-effect mobility and on/off current ratio; (b) surface treatment of SiNx gate dielectric with a combination of O2 plasma and octyltrichlorosilane (OTS) self-assembled monolayer (SAM) delivers the best OTFT performance; (c) an optimal O2 plasma treatment duration exists for attaining highest field-effect mobility and is linked to a “turn-around” effect; and (d) surface treatment of the gold (Au) source/drain contacts by 1-octanethiol SAM limits mobility and should be omitted. There is a strong correlation between the electrical characteristics and the interfacial characteristics of OTFTs. In particular, the device mobility is influenced by the interplay of various interfacial mechanisms, including surface energy, surface roughness, and chemical composition. Finally, the collective knowledge from these investigations facilitates the integration of OTFTs into organic circuits, which is expected to contribute to the development of new generation of all-organic displays for communication devices and other pertinent applications. A major outcome of this work is that it provides an economical means for organic transistor and circuit integration, by enabling use of the well-established PECVD infrastructure, yet not compromising the performance of electronics.

The broad theme of the present research investigation is Ion Assisted Deposition of thin films and its effect on the properties of thin films. Though this activity has been of interest to researchers for more than a decade, the development of different types of ion sources with control over the ion flux and energy, makes it a current topic of interest. Ion assisted deposition was successful in depositing thin films of many material with desired qualities, however, there are certain class of materials whose deposition has been rather difficult. This has mainly been attributed to higher energies and low ion flux of conventional ion sources. The advent of ECR ion sources for thin film deposition has given impetus to the deposition of such materials. This is due to the low energy high-density plasma generated in this type of sources. Hitherto, these sources were widely used in PECVD techniques and only recently the importance of ECR sources in PVD techniques has been realized. This thesis is on the development of ECR plasma source for ion assisted deposition of thin films using PVD techniques. This thesis is organized into six chapters. The first chapter gives an introduction on the ion assisted growth of thin films and the importance of ECR plasma. A detailed discussion on various aspects of ECR sources has been included. The design details on the development of ECR source have been discussed in the second chapter. The performance of ECR source as analyzed by the Langmuir probe are also discussed. Variation of plasma parameters like ion density, electron temperature, plasma potential and floating potential as a function of pressure and microwave power have been studied using Langmuir probe analysis. An ion density of the order of 1011/cm3 was measured at a distance of 8 cm from the plasma source with a microwave power of 400 watts. This was comparable to the ion density reported in downstream plasma of ECR sources. The behavior of plasma parameters with variation in microwave power and pressure was explained on the basis of microwave transmission above critical ion density and the microwave power absorption. The uniformity of the plasma parameters at the substrate position (29 cm from the ECR source) was found to be ± 2% over a diameter of 12 cm, which makes the ion source suitable for ion assisted deposition. The third chapter deals with the simulation and experimental study of the ECR sputtering process. ECR sputter type sources are equipped with cylindrical targets. The sputtered flux distribution on the substrate depends on target geometry, sputtering pressure and target-substrate distance. The effect of cylindrical geometry on the distribution of sputtered flux has been simulated by Monte Carlo methods. It is found that the sputtered flux distribution at different pressures and target-substrate distances in ECR sputter type source differs from the conventional glow discharge sputtering system equipped with planar targets. The simulated results are compared with the experimental results. The simulated data agree very well with the experimental data. The deposition and characterization of the TiN thin films for diffusion barrier applications in copper metallization have been discussed in the fourth chapter. Titanium nitride films are prepared by ECR sputtering. The effect of high density ion bombardment on the morphology, orientation and resistivity of the films was studied. It was observed that films with atomic smoothness could be prepared by ECR sputtering. Also the high density ion bombardment has been found to be effective for the film growth in (100) orientation. The behavior of TiN films deposited by this method as a diffusion barrier in copper metallization has been investigated. The resistivity measurements and RBS depth profile studies showed that up to 700°C there is no diffusion of copper into silicon. This shows that ECR sputtered TiN can be used as an effective diffusion barrier in copper metallization. The fifth chapter contains investigations on the ECR assisted growth of silicon nitride films. The films are characterized for composition, morphology and chemical bonding using AES, RBS, AFM, XPS and FTIR. AFM studies revealed that ion bombardment results in the reduction of surface roughness, which indicates dense film growth. The effect of ion assistance on the optical and electrical properties is studied in detail. Films prepared with microwave power ranging from 100 to 200 watts are having bandgap and refractive index of 4.9 eV and 1.92 respectively. Interface state density of silicon nitride films prepared in the above mentioned range was found to be 5x10 10 eVcm2. These films exhibited a resistivity of 10 13 Ω, cm and critical field of 4 MV/cm. The electrical conductivity in these films has been explained on the basis of Poole and Frenkel conduction. The low value of interface state density, higher resistivity, and critical field show that good quality SiN4 films can be deposited with low energy high density ECR plasma. A detailed summary of this research investigation has been discussed in the last chapter. The thesis is concluded with a discussion on the need of focused ECR source to establish ECR assisted deposition as a versatile technique for the growth of thin films.

Als Graphen bezeichnet man eine einzelne freistehende Lage des Schichtkristalls Graphit. Im Gegensatz zur mechanischen Isolation von Graphit bietet die Züchtung auf Siliziumkarbid eine Methode zur großflächigen Herstellung von Graphen. Aufgrund der besonderen physikalischen Eigenschaften werden für Graphen viele verschieden Einsatzmöglichkeiten in diversen Bereichen prognostiziert. Mit seiner hohen Ladungsträgerbeweglichkeit ist Graphen besonders als Kanalmaterial für Feldeffekttransistoren (FET) interessant. Allerdings muss hierfür unter anderem ein geeignetes FET-Isolatormaterial gefunden werden. In dieser Arbeit wird eine detaillierte, theoretische Beschreibung der Graphen-FETs vorgestellt, die es erlaubt die steuerspannungsabhängige Hall-Konstante zu berechnen. Mit der dadurch möglichen Analyse können wichtige Kenngrößen, wie z. B. die Grenzflächenzustandsdichte des Materialsystems bestimmt werden. Außerdem wurden zwei Methoden zur Isolatorabscheidung auf Graphen untersucht. Siliziumnitrid, welches mittels plasmaangeregter Gasphasenabscheidung aufgetragen wurde, zeichnet sich durch seine n-dotierende Eigenschaft aus. Damit ist es vor allem für quasi-freistehendes Graphen auf Siliziumkarbid interessant. Bei der zweiten Methode handelt es sich um einen atomaren Schichtabscheidungsprozess, der ohne eine Saatschicht auskommt. An beiden Graphen- Isolator-Kombinationen wurde die neue Charakterisierung mittels der Hall-Datenanalyse angewandt.

Mo-Si-B alloys are a leading candidate for the next generation of jet turbine engine blades and have the potential to raise operating temperatures by 300-400°C. The alloys of interest are a three-phase mixture of the molybdenum solid solution (Moss) and two intermetallic phases, Mo3Si (A15) and Mo5SiB2 (T2). A novel powder metallurgical method was developed which uses the reaction of molybdenum, silicon nitride (Si3N4) and boron nitride (BN) powders to synthesize a fine dispersion of intermetallics in a Moss matrix. The covalent nitrides are stable in oxidizing environments up to 1000ºC, allowing for fine particle processing. The process developed uses standard powder processing techniques to create Mo-Si-B alloys in a less complex and expensive manner than previously demonstrated. This powder metallurgy approach yields a fine dispersion of intermetallics in the Moss matrix with average grain sizes of 2-4μm. Densities up to 95% of theoretical were attained from pressureless sintering at 1600°C and full theoretical density was achieved by hot-isostatic pressing (HIP). Sintering and HIPing at 1300°C reduced the grain sizes of all three phases by over a factor of two. Microstructure examination by electron back-scatter diffraction imaging was used to precisely define the location of the phases and to measure the volume fractions and grain size distributions. Microstructural quantification techniques including two-point correlation functions were used to quantify microstructural features and correlate the BN reactant powder size and morphology to the distribution of the intermetallic phases. High-temperature tensile tests were conducted and yield strengths of 580MPa at 1100°C and 480MPa at 1200°C were measured for the Mo-2Si-1Bwt.% alloy. The yield strength of the Mo-3Si-1Bwt.% alloy was 680MPa at 1100°C and 420MPa at 1300°C. A review of the pertinent literature reveals that these are among the highest yield strengths measured for these compositions. The oxidation resistance in air at 1000 and 1100°C was examined. The protective borosilicate surface layer formed quickly due to the close spacing of intermetallic particles and pre-oxidation treatment was developed to further limit the transient oxidation behavior. An oxidation model was developed which factors in the different stages of oxidation to predict compositions that minimize oxidation.

Made available in DSpace on 2014-12-17T14:07:04Z (GMT). No. of bitstreams: 1 JulianaPN_DISSERT.pdf: 2953662 bytes, checksum: 47355bc7fed206f60c6c6b5d8565099b (MD5) Previous issue date: 2012-06-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Nickel alloys are frequently used in applications that require resistance at high temperatures associated with resistance to corrosion. Alloys of Ni-Si-C can be obtained by means of powder metallurgy in which powder mixtures are made of metallic nickel powders with additions of various alloying carriers for such were used in this study SiC, Si3N4 or Si metal with graphite. Carbonyl Ni powder with mean particle size of 11 mM were mixed with 3 wt% of SiC powders with an average particle size of 15, 30 and 50 μm and further samples were obtained containing 4 to 5% by mass of SiC with average particle size of 15 μm. Samples were also obtained by varying the carrier alloy, these being Si3N4 powder with graphite, with average particle size of 1.5 and 5 μm, respectively. As a metallic Si graphite with average particle size of 12.5 and 5 μm, respectively. The reference material used was nickel carbonyl sintered without adding carriers. Microstructural characterization of the alloys was made by optical microscopy and scanning electron microscopy with semi-quantitative chemical analysis. We determined the densities of the samples and measurement of microhardness. We studied the dissociation of carriers alloy after sintering at 1200 ? C for 60 minutes. Was evaluated also in the same sintering conditions, the influence of the variation of average particle size of the SiC carrier to the proportion of 3% by mass. Finally, we studied the influence of variation of the temperatures of sintering at 950, 1080 and 1200 ? C without landing and also with heights of 30, 60, 120 and 240 minutes for sintering where the temperature was 950 ?C. Dilatometry curves showed that the SiC sintered Ni favors more effectively than other carriers alloy analyzed. SiC with average particle size of 15 μm active sintering the alloy more effectively than other SiC used. However, with the chemical and morphological analyzes for all leagues, it was observed that there was dissociation of SiC and Si3N4, as well as diffusion of Si in Ni matrix and carbon cluster and dispersed in the matrix, which also occurred for the alloys with Si carriers and metallic graphite. So the league that was presented better results containing Si Ni with graphite metallic alloy as carriers, since this had dispersed graphite best in the league, reaching the microstructural model proposed, which is necessary for material characteristic of solid lubricant, so how we got the best results when the density and hardness of the alloy / Ligas de N?quel s?o freq?entemente utilizadas em aplica??es que requerem resist?ncia mec?nica a elevadas temperaturas associada ? resist?ncia ? corros?o. Ligas de Ni-Si-C podem ser obtidas por meio de metalurgia do p? em que s?o realizadas misturas de p?s de n?quel met?lico com adi??es de p?s de diferentes portadores de liga, para tal foram utilizados neste trabalho SiC, Si3N4 ou Si met?lico com grafita. P?s de Ni carbonila com tamanho m?dio de part?culas de 11 μm foram misturados a 3% em massa de p?s de SiC com tamanho m?dio de part?culas de 15, 30 e 50 μm e foram obtidas ainda amostras contendo 4 e 5% em massa de SiC com tamanho m?dio de part?culas de 15 μm. Tamb?m foram obtidas amostras variando-se o portador de liga, sendo estes p?s de Si3N4 com grafita, com tamanho m?dio de part?culas de 1,5 e 5 μm, respectivamente. Assim como Si met?lico com grafita, com tamanho m?dio de part?culas de 12,5 e 5 μm, respectivamente. O material de refer?ncia adotado foi n?quel carbonila sinterizado sem adi??o de portadores. A caracteriza??o microestrutural das ligas foi feita por microscopia ?ptica e eletr?nica de varredura com an?lise qu?mica semi-quantitativa. Foram determinadas as densidades das amostras e obtidas medidas de microdureza Vickers. Foi estudada a dissocia??o dos portadores de liga ap?s sinteriza??o em 1200 ?C durante 60 minutos. Foi avaliada, ainda, para as mesmas condi??es de sinteriza??o, a influencia da varia??o do tamanho m?dio de part?culas do portador SiC, para a propor??o de 3% em massa. Por fim, foi estudo a influencia da varia??o das temperaturas de sinteriza??o em 950, 1080 e 1200 ?C sem patamar e, ainda, com patamares de 30, 60, 120 e 240 minutos para sinteriza??o cuja temperatura foi de 950 ?C. As curvas de dilatometria mostraram que o SiC favorece a sinteriza??o do Ni de forma mais eficaz que os demais portadores de liga analisados. O SiC com tamanho m?dio de part?culas de 15 μm ativa a sinteriza??o da liga de forma mais eficaz que os demais SiC utilizados. Por?m, com as an?lises qu?mica e morfol?gica para todas as ligas, foi poss?vel observar que houve dissocia??o do SiC e do Si3N4, assim como difus?o do Si na matriz de Ni e carbono aglomerado e disperso na matriz, o que tamb?m ocorreu para as ligas com portadores Si met?lico e grafita. Portanto, a liga que apresentou melhores resultados foi de Ni contendo Si met?lico com grafita como portadores de liga, j? que esta apresentou grafita melhor dispersa na liga, atingindo o modelo microestrutural proposto, do qual ? necess?rio para material com caracter?stica de lubrificante s?lido, assim como obteve os melhores resultados quando a densidade e dureza da liga

Afin de comprendre les mécanismes de transport de la chaleur dans des films très minces des matériaux amorphes, nous avons proposé et démontré expérimentalement une nouvelle technique de mesure des propriétés thermiques de membranes très minces. Cette technique consiste à coupler la méthode 3 oméga avec la géométrie Völklein (membrane suspendue allongée). L'échantillon d'intérêt est alors monté dans un pont de Wheatstone spécifique afin d'éliminer le signal électrique 1 oméga. Cette technique permet de mesurer avec une très haute sensibilité le signal thermique 3 oméga et donc les propriétés thermiques des membranes. Le nitrure de silicium étudié dans ce travail constitue un matériau amorphe typique. Nous avons été intéressés par l'étude du transport thermique dans un tel système de dimensions réduites en fonction de la température et du stress intrinsèque qui présente dans les films. Afin d'atteindre cet objectif, les membranes de nitrure de silicium de stress élevé et de faible niveau de stress ont été mesurées respectivement pour une épaisseur de 50 nm et 100 nm. Le comportement global de la conductivité thermique mesurée est une croissance quand la température augmente, une tendance généralement constaté pour un matériau amorphe. Le data de membrane de 50 nm présente une conductivité thermique inférieure à celle du 100 nm, ce qui est en accord avec l'effet des dimensions réduites. La chaleur spécifique mesurée s'écarte sensiblement de la loi en T3 de Debye. Cela est particulièrement important en dessous de 100 K où la chaleur spécifique est plus élevé que celle prévue par la modèle Debye. Ces résultats expérimentaux sont en excellent accord avec les prévisions d'un model théorique qui tient en compte de l'effet TLS (Two Level System) qui présente dans le matériaux amorphe. Il a été montré expérimentalement que le stress n'a pas d'effet sur la chaleur spécifique de nitrure de silicium. De plus, nous avons démontré que le stress n'affecte pas la dissipation dans nitrure de silicium, et la dissipation par dilution semble être la cause de la réduction de la dissipation. Par conséquent, le stress ne devrait pas affecter la conductivité thermique du nitrure de silicium, ce qui est cohérent avec les résultats expérimentaux. En terme d'application de la méthode 3 oméga-Völklein, nous avons démontré que la membrane de SiN peut être utilisée comme capteur thermique spécifique pour caractériser un autre matériau déposée sur la face arrière de la membrane. Nous avons testé ce modèle pour mesurer les propriétés thermiques d'un film de 200 nm de Bi2Te3. Les résultats obtenus sont en excellent accord avec la littérature. Comme le SiN est un matériau isolant, ce modèle est capable de mesurer des films très minces quelle que soit sa nature, isolant, semi conducteur ou métallique. / In order to understand the mechanisms of the heat transport in very thin amorphous films, we have proposed and experimentally demonstrated a new technique to measure the thermal properties of very thin membranes. This technique consists in coupling the 3 omega method to the Völklein geometry (elongated suspended membrane). The sample of interest is then implemented into a specific Wheatstone bridge in order to eliminate the electrical 1 omega signal. This technique allows the measurement with very high sensitivity of the 3 omega thermal signal and therefore the thermal properties of the membranes. Silicon nitride membranes studied in this work constitutes a typical amorphous material. We have been interested in the study on the thermal transport in such system of reduced dimensions as function of temperature and intrinsic modified stress. In order to accomplish this goal, silicon nitride membranes of high stress and low stress have been measured respectively with the thickness 50 nm and 100 nm. The overall behaviour of the measured thermal conductivity is an increase as the temperature is increased, a trend commonly found for amorphous material. The 50 nm data show thermal conductivity less than that of the 100 nm, this is consistent of the effect of reduced dimensions. The measured heat capacity is apparently higher than what is expected from the Debye phonon heat capacity. This is especially significant below 100 K where the heat capacity deviates significantly from the T3 Debye law. A theoretical model taking into account the presence of TLS in amorphous materials is then used to fit the experimental data. The theoretical fits are in excellent agreement with the experimental results. It was seen experimentally that stress has no effect on the specific heat of silicon nitride. Moreover, we have demonstrated that stress does not affect the dissipation in silicon nitride, and the dissipation dilution seems to be the sole cause of the reduction of dissipation by an applied stress in high stress silicon nitride. Therefore, stress should not affect thermal conductivity of silicon nitride, and this is consistent with the experimental results. As application for the 3 omega-Völklein method, we have demonstrated that the SiN membrane can be used as specific thermal sensor to characterize another material deposited on the backside of the membrane. We have tested this model to measure thermal properties of Bi2Te3 film and the results are in excellent agreement with literature. As the SiN is an insulator, this model is able to measure very thin films whatever its nature, insulator, semi conductor or metallic.

Foram realizados ensaios tribológicos de deslizamento do par Si3N4-Al2O3, lubrificado com água, na configuração esfera contra disco, sendo a esfera de nitreto de silício e o disco de alumina para investigar a influência da velocidade de deslizamento, da carga aplicada e da temperatura no coeficiente de atrito. As esferas de nitreto de silício e os discos de alumina foram caracterizados determinando-se: densidades, dureza Vickers, módulo de elasticidade e tenacidade à fratura. Os ensaios foram realizados com rugosidade inicial nos discos de Rrms = 352 nm. O regime de ultra baixo coeficiente de atrito (UBCA, &#956; < 0,01) foi atingido após um período de running-in de aproximadamente uma hora e o coeficiente de atrito ficou na faixa de &#956; = 0,008 a &#956; = 0,002. Os resultados mostraram que este sistema deslizante tem características hidrodinâmicas, pois o coeficiente de atrito diminuiu com o aumento da velocidade de deslizamento. Uma variação suave da carga aplicada fez com que o coeficiente de atrito permanecesse no regime de UBCA, com a carga aplicada variando de 54 N até 94 N. Em temperaturas menores ou iguais a 11°C o sistema não atingiu o regime de UBCA e o coeficiente de atrito final ficou da ordem de centésimos. Foi observado o fenômeno de UBCA em temperaturas de 30 e 40°C. No entanto, nestas temperaturas, a baixa viscosidade da água não deveria permitir que o sistema atingisse o regime de UBCA. A análise dos dados possibilitou inferir que durante o regime de UBCA o sistema desliza num regime de lubrificação mista, sendo lubrificação hidrodinâmica, devido ao filme de água, somada a lubrificação limite, devido às camadas hidratadas formadas nas superfícies das cerâmicas. Os resultados mostraram que a temperatura influencia no desgaste das cerâmicas. A determinação do volume desgastado possibilitou observar que durante os ensaios a alumina sofre menos desgaste que o nitreto de silício e que o desgaste de ambas cerâmicas aumenta com o aumento da temperatura. / Tribological tests were conducted in a ball on disk setup, using water as lubricant. Were used a silicon nitride ball and alumina disk. The tests were conducted to investigate the effects of sliding speed, applied load and temperature on friction coefficient. The silicon nitride balls and alumina disks were characterized by determining density, Vickers hardness, elastic modulus and fracture toughness. The tests were conducted with initial roughness on the disk surface of 352 nm. The ultra low friction coefficient regime (ULFC, &#956; < 0.01) was reached after a running-in period of approximately one hour and the friction coefficient remains in the range of &#956; = 0.008 a &#956; = 0.002 during this steady state regime. The results showed that this sliding system has hydrodynamic characteristics, because the friction coefficient decreased with increasing of the sliding speed. With an smooth variation of the applied load the system remained in the ULFC regime, when the applied load varied from 54 N up to 94 N. At temperatures below or equal to 11°C the system did not reach the ULFC regime and the final friction coefficient was the order of hundredths. We observed the ULFC phenomenon at temperatures of 30 and 40°C. However, at these temperatures, the water viscosity is low and should not allow the system to reach the ULFC regime. The data analysis allowed infer that during the ULFC regime the system slides with a mixed lubrication regime, hydrodynamic plus limitrofe, the first due to water film and the second due to the hydrated layer formed on the ceramics surfaces. The results showed a influences of temperature in the ceramics wear. The results of the worn volume allowed to observe that during the tests alumina suffers less wear than the silicon nitride, and the ceramics wear increases with increasing temperature.

Orientador: Jose Alexandre Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-05T17:29:59Z (GMT). No. of bitstreams: 1 Biasotto_Cleber_M.pdf: 4466326 bytes, checksum: 75500d469b99d21f5c40a3214a755168 (MD5) Previous issue date: 2005 / Resumo: Neste trabalho, filmes finos de nitreto (SixNy), oxido (SiOx) e oxinitreto (SiOxNy) de silicio sobre substrato de silicio, obtidos através da deposição química a partir da fase vapor auxiliada por plasma remoto (RPCVD), foram caracterizados e estudados para aplicações em micromáquinas (micromachining) ou sistemas micro-eletro-mecanico (MEMS). Os filmes de nitreto de silicio (SixNy) foram obtidos para aplicação em estruturas suspensas (pontes e membranas) e como mascara de proteção de dispositivos MOS para remoção do substrato, utilizando os processos de corrosão úmida do substrato de silicio pelas faces superior (front-side bulk micromachining) e inferior (back-side bulk micromachining), respectivamente. Os filmes de oxido de silicio (SiOx) foram aplicados como camada sacrificial em processos de obtenção de estruturas suspensas empregando a técnica de remoção de camadas sacrificiais na superfície (surface micromachining). Os filmes de oxinitreto de silicio (SiOxNy) foram obtidos como filmes alternativos para aplicação em estruturas suspensas (pontes e membranas), utilizando os processos de corrosão úmida do substrato de silicio pela face superior (front-side bulk micromachining). A fabricação destas estruturas e primordial para o desenvolvimento de micro-sensores e micro-atuadores. Neste trabalho foram revisadas as técnicas de processamento CVD (Chemical Vapor Deposition), apresentando a justificativa da escolha do reator ECR (Electron Cyclotron Resonance), que utiliza a tecnologia CVD com Plasma Remoto (RPCVD) para as deposições / Abstract: In this work, silicon nitride (SixNy), oxide (SiOx) and oxynitride (SiOxNy) thin films obtained by remote plasma chemical vapor deposition (RPCVD) on silicon substrate were studied and characterized for micromachining or micro electro-mechanical system (MEMS) applications. Silicon nitride films (SixNy) were used in suspended structures (membranes and bridges) and as MOS device protection mask against wet substrate etching, obtained by wet substrate etching processes using the front-side and back-side bulk micromachining techniques, respectively. Silicon oxide films (SiOx) were employed as sacrificial layers to obtain suspended surface structures using the surface micromachining technique. Silicon oxynitride (SiOxNy) films were used as alternative films in suspended structures (membranes and bridges), using the front-side bulk micromachining technique. The fabrication of these structures is primordial for the micro sensor and actuator development. In these work, CVD (Chemical Vapor Deposition) techniques are revised, presenting the choice justification of ECR (Electron Cyclotron Resonance) reactor, which uses RPCVD technology for the depositions / Mestrado / Mestre em Engenharia Elétrica

Orientador: Ioshiaki Doi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T12:57:52Z (GMT). No. of bitstreams: 1 Pereira_MarcusAnibal_M.pdf: 4318576 bytes, checksum: 61cdc38456d21cf10bf9ccfef5d0bff4 (MD5) Previous issue date: 2005 / Resumo: Isolantes de nitreto de silício (SiNx) para aplicação na tecnologia de isolação LOCOS foram depositados por ECR-CVD a temperatura ambiente e RP/RTCVD, a baixa pressão (5mTorr), com fluxos de gás de N2 de 2.5, 5, 10 e 20sccm, com fluxos de gases de SiH4/Ar fixos de 200sccm/20sccm, e potência de microondas de 1000W em substratos de SiO2-Pad/Si e Si. As estruturas de SiNx/SiO2-Pad/Si e SiNx/Si obtidas foram utilizadas para analisar as características físicas do nitreto de silício. Análises de espectroscopia de infravermelho (FTIR) revelaram a presença de trocas de posição do pico principal das ligações Si-N, das ligações N-H e das ligações Si-N (modo de vibração stretching) nos filmes de nitreto de silício, que está relacionado aos fluxos de N2 na mistura de gases. Os índices de refração entre 1.88 e 2.48 e as espessuras entre 120nm e 139nm foram determinados através de elipsometria. Com estes valores de espessura e com os tempos de ataque em Buffer de HF, foram determinadas as taxas de deposição de 9,6 a 11,1nm/min e taxas de corrosão de 2 a 86nm/min. O processo LOCOS, com etapas seqüenciais de fotolitografia e oxidação térmica, foi executado nas estruturas de SiNx/SiO2-Pad/Si e também de SiNx/Si (sem a presença de óxido "almofada"), com a espessura de cada tipo de nitreto entre 110nm a 215nm e espessura do óxido ?almofada? de 0 a 124nm. Análises de microscópio óptico e de microscopia eletrônica de varredura (SEM) foram utilizadas respectivamente para investigar a resistência dos nitretos de silício à oxidação térmica, executada sob altas temperaturas (1000ºC) e o efeito ?bico de pássaro? formado nas estruturas LOCOS. O nitreto depositado com fluxo de N2 de 10sccm (N10) foi o que apresentou a menor invasão lateral por parte do óxido de campo dentre os nitretos estudados, tanto com quanto sem a camada de óxido de ?almofada? sob o nitreto. O efeito "bico de pássaro" formado nas estruturas LOCOS teve comprimento de avanço lateral variando de 330nm a 2160nm tomando como base a oxidação local executada em temperatura de 1000ºC durante 180 minutos / Abstract: Silicon nitride (SiNx) insulators for LOCOS applications have been deposited by RP/RTCVD and ECR-CVD at room temperature, at low pressure (5mTorr), with N2 flows of 2.5, 5, 10 and 20sccm with fixed SiH4/Ar flows of 200/20sccm with a microwave power of 1000W on SiO2-Pad/Si and Si substrates. SiNx/Si structures were obtained to analyze the physical characteristics of silicon nitride. Fourier transform infrared (FTIR) spectrometry analyses revealed the main peak position shifts of Si-N, N-H and Si-N (stretching mode) bonds for each silicon nitride films, which is related to N2 flows in gas mixture. The refractive indexes between 1.88 and 2.48 and the thickness between 120nm and 139nm were determined by ellipsometry. With these thickness values and with buffered HF etching times, it was also determined the deposition rates of 9,6 - 11,1nm/min and etch rates of 2 -86nm/min. On the SiNx(110 -215nm)/SiO2-Pad(0 - 124nm)/Si and SiNx/Si (without pad oxide) structures, the LOCOS process, with sequential photolithography and thermal wet oxidation steps, was performed. Optical and scanning electron microscopy (SEM) analysis were used to investigate the silicon nitride to thermal oxidation accomplishement at high temperature of 1000 ºC, and bird's beak in the obtained LOCOS structures. On both structures (with and without pad oxide), the smallest lateral extension of the field oxide (bird's beak) was observed for the nitride films obtained with N2 flows of 10sccm (N10). The lengths of the bird's beak, in the obtained LOCOS structure, have resulted between 330nm and 2160nm / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica