Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Melkote, Shreyes; Committee Member: Danyluk, Steven; Committee Member: Griffin, Paul; Committee Member: Johnson, Steven; Committee Member: Kalejs, Juris; Committee Member: Sitaraman, Suresh. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--Lehigh University, 1996. / Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. Jim P. Zheng, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains xii, 96 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04Bitstream added on 2014-06-13T20:37:38Z : No. of bitstreams: 1 costa_dj_me_guara.pdf: 959258 bytes, checksum: 07963064751da13bd2ff1173cba566ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho teve como objetivo a obtenção de pastilhas cerâmicas Al2O3/TiO2 e as caracterizações térmica e mecânica das camadas destas pastilhas. As pastilhas foram obtidas pelos processos de conformação direta com amido comercial e por prensagem. Nesta dissertação são apresentados os moldes metálicos e de polímeros para confecção dos corpos de prova para o ensaio mecânico de resistência à flexão, e para o ensaio térmico à flexão seguiram a norma ASTM C1161. Na caracterização térmica, é analisado o coeficiente de expansão térmica. na caracterização mecânica, são analisados a reistência mecânica à flexão e o valor da flecha de deformação do corpo de prova. Verificou-se que a aplicação de um gradiente de porosidade reduz as tensões residuais térmicas na pastilha. / This work aimed the acquisition of Al2O2/TiO2 ceramic wafers and their thermal and mechanical characterization. The wafers have been obtained by starch consolidation process and pressing. In this dissertation are presented metallic and polymeric moulds to obtain the samples for mechanical and thermal tests. Mechanical tests of flexural mechanical strength and thermal tests of dilation have been achieved. The measurements of the samples for flexural mechanical strenth testing followed the ASTM C1161 standard. The thermal dilation coefficient is analyzed in the thermal characterization. In the mechanical characterization are analysed the flexural mechanical strenght and the maximum deformation arrow of the samples. A reduction of the residual thermal stresses by aplication of a gradient of porous has been verified.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Silicon is the primary semiconductor material used to fabricate integrated circuits (ICs). The quality of integrated circuits depends directly on the quality of silicon wafers. A series of processes are required to manufacture the high-quality silicon wafers. Chemical mechanical polishing is currently used to manufacture the silicon wafers as the final material removal process to meet the ever-increasing demand for flatter wafers and lower prices. A finite element analysis has been conducted to study the effects of influencing factors (including Young's modulus and Poisson's ratio of the polishing pad, thickness of the pad, and polishing pressure) on the wafer flatness. In addition, an experimental study was carried out on the effects of process variables (including wafer rotation speed, pad rotation speed, the temperature of the cooling wafer in polishing table, polishing pressure, and the slurry flow rate) on material removal rate (MRR) in polishing of silicon wafers. The results from this study show that the polishing pressure and the pad speed are the most significant factors affecting the MRR. The polishing pad is one of the most critical factors in planarizing the wafer surface. It transports the slurry and interacts with the wafer surface. When the number of polished wafers increases, the pad is glazed and degraded and hence the polishing quality is decreased. The pad properties are changed during the process. The measuring methods for the pad properties including pad thickness monitoring, elastic properties and hardness are reviewed. Elasticity of two types of pads are measured and compared. The poor flatness problems such as tapering, edge effect, concave or convex wafer shape were investigated. Finite element models were developed to illustrate the effects of polishing pad and carrier film properties on the stress and contact pressure distribution on the wafer surface. Moreover, the material removal unevenness is studied. A grinding-based manufacturing method has been investigated experimentally to demonstrate its potential to manufacture flat silicon wafers at a lower cost. It has been demonstrated that the site flatness on the ground wafers (except for a few sites at the wafer center) could meet the stringent specifications for future silicon wafers. One of the problems is the poor flatness at the wafer center: central dimples on ground wafers. A finite element model is developed to illustrate the generation mechanisms of central dimples. Then, effects of influencing factors (including Young's modulus and Poisson's ratio of the grinding wheel segment, dimensions of the wheel segment, grinding force, and chuck shape) on the central dimple sizes are studied. Pilot experimental results are presented to substantiate the predicted results from the finite element model. This provides practical guidance to eliminate or reduce central dimples on ground wafers. The study in this thesis is to understand the mechanism of CMP and grinding of silicon wafers. Improving the processes and the quality of silicon wafers are the final goals.

La connaissance des interactions interfaciales et l'énergie de surface est nécessaire pour étudier et modéliser les processus qui se déroulent dans le mouillage, l'adhésion ou la diffusion. Tels phénomènes sont rencontrés dans la préparation des suspensions, des émulsions et les peintures. Dans ce contexte, l'énergie de surface représente un paramètre important dans l'étude des propriétés interfaciales solide/liquide où plusieurs applications sont impliquées. Nous avons étudié l'effet de la modification chimique sur l'énergie de surface de deux silices choisies selon deux différentes échelles: l'OX qui présente un substrat nanométrique et les wafers de silicium qui est un substrat millimétrique. Pour la silice OX 50, La modification chimique de la surface a été réalisée avec l'hexadecyltrichlosilane (HTS) à caractère hydrophobe. L'infrarouge en transmission et la quantification de carbone organique ont été efficaces pour estimer les quantités croissantes d'HTS greffées à la surface de la silice. Deux isothermes d'adsorption ont été tracées. Ensuite, la volumétrie d'adsorption continue d'argon et d'azote a été utilisée pour étudier l'évolution de l'hétérogénéité énergétique. Ceci a été achevé en faisant recours à une stratégie d'analyse de volume adsorbée à la monocouche (Vm) d'azote et d'argon. Les résultats obtenus ont servi pour tracer une troisième isotherme d'adsorption. La quantification de l'énergie de surface a été réalisée avec la montée capillaire (technique macroscopique) et la chromatographie gazeuse en phase inverse (CGI) (technique moléculaire). Pour les wafers de silicium, deux types de surfaces ont été élaborées durant cette étude. Le premier hydrophile (traitement Piranha, formations des groupements OH). Cette surface a été obtenue par oxydation de ces wafers (traitement Piranha). La deuxième a été obtenue par le greffage d'HTS (greffons CH3). La quantification de l'énergie de surface a été réalisée avec la mouillabilité (technique macroscopique) et la microscopie à force atomique (AFM) (technique nanoscopique). Enfin, les différentes valeurs d?énergie de surface de la silice vierge OX 50 ont été comparées avec celles de la surface plane hydrophile (OH). Pour les surfaces hydrophobes, on a comparé les valeurs d?énergie de surface de la silice OX 50 modifiée d'une quantité maximale d?HTS avec le wafer de silicium à greffons CH3 / The knowledge about interfacial free energy interactions and surface energy is necessary for understanding and modeling many surface and interface processes. The investigation of the surface properties of solids is very important in several applications such as wetting, spreading and adhesion processes. Such processes occur during the preparation of suspensions, emulsions, painting, printing and corrosion protection. Knowledge about surface free energy of solids appears as a very important parameter determining the interfacial properties in solid/liquid and solid/gas interfaces where many implementations are involved. We have studied the effect of the chemical modification on surface energy for two types of silica: Aerosil OX 50 is chosen as a nanometric substrate and the wafers of silicium chosen as micrometric substrate. For silica OX 50, the chemical modification was carried out using the hydrophobic hexadecyltrichlorosilane (HTS). Transmission infrared and the quantification of organic carbon were helpful in the estimation of increasing quantities of HTS grafted to the surface. Two adsorption isotherms were drawn. Then, continuous adsorption isotherm of argon and nitrogen was used to study the evolution of energetic heterogeneity in the course of the chemical reaction. This was achieved by applying an analysis strategy of the monolayer volume (Vm) of adsorbed argon and nitrogen. Results enabled the drawing of a third adsorption isotherm. The quantification of surface energy for various samples was realize using capillary rise (macroscopic technique) and inverse gas chromatography (IGC) (molecular technique). For silicon wafers, two types of surfaces were elaborated in this study. The first hydrophilic (OH grafting), was obtained by oxidation of silicon wafers (Piranha treatment), the second hydrophobic (CH3 grafting), was obtained by grafting HTS molecules to the surface. The quantification of the surface free energy was achieved using the wettability (macroscopic technique) and the atomic force microscopy (AFM) (nanoscopic technique). Finally the different values of surface free energy obtained for native silica are compared to those of hydrophilic (OH) flat surfaces. As for hydrophobic surfaces, the silica OX 50 modified with maximum quantity of HTS is compared to Hydrophobic (CH3) flat surfaces

Le collage direct est un procédé par lequel deux surfaces suffisamment planes et propres peuvent se coller sans ajout d'un adhésif. Le collage direct de surfaces structurées est souvent utilisé pour la fabrication de système mécanique microélectronique (MEMS), où une plaque de silicium avec des cavités est collée à une autre plaque de silicium. La fabrication de ces dispositifs est chère et il serait utile d'avoir une ligne directrice lors du dessin de structures afin de savoir à l'avance si le collage direct sera possible.Un modèle de simulation 2D pour le collage direct de deux substrats est développéet utilisé pour étudier l'influence des cavités sur la vitesse de propagation de l'ondede collage. Les prédications données par des simulations avec Comsol® sont en bonnecohérence avec les mesures expérimentales et une loi en 2 dimensions de la vitesse de collage est obtenue. Le collage de plaques parfaitement planes avec des cavités serait toujours possible. Les limitations lors du collage de vraies plaques sont dues au coût de l'énergie élastique pour déformer les plaques non parfaitement planes. Cette limite est atteinte facilement quand l'onde de collage doit traverser une tranchée, dans ce cas un dessin avec un petit guide de collage pour aider à traverser la cavité fonctionnera mieux. La taille de ce guide d'onde doit être choisis en considèrent la flèche de la plaque. En effet la seconde règle importante du dessin est de garder une surface de collage suffisante pour avoir plus d'énergie d'adhésion que le coût en énergie élastique dû à la déformation des plaques non parfaitement planes.L'énergie d'adhésion est un important paramètre du collage direct, car c'est l'énergie qui permet l'adhésion. Cette énergie d'adhésion est différente de l'énergie de collage la plus répandues qui est l'énergie requise pour séparer deux plaques précédemment collées. Dans cet ouvrage une méthode simple de mesure d'adhésion est proposée. Une mesure de l'évolution de l'énergie d'adhésion sur un temps long nous mène à proposer un mécanisme d'évolution lié à la formation de ponts capillaires entre des surfaces rugueuses. / Direct bonding is a process by which two sufficiently flat and clean surfaces can bond to each other without any added adhesive layer. Direct bonding of patterned surfaces is often used for the fabrication of Micro-Electro-Mechanical Systems (MEMS), where a silicon wafer with cavities is bonded to a plain wafer. The fabrication of these devices is expensive and it would be useful to have guidelines when designing knew devices to know in advance if direct bonding will be possible.A 2D simulation model of the direct bonding of two substrates is developed and usedto study the influence of the cavities on the bonding wave velocity. The prediction of the simulation run with Comsol® are in good coherence with the experimental measures and a 2D law of the bonding velocity is obtained. The bonding of perfectly flat wafers with cavities should always be possible. Limitations to the bonding of real wafers are due to the elastic energy cost of deforming the non perfectly flat wafers. This limit is reached easily when the bonding wave must cross a trench, so a design with a small bonding guide to help cross the cavity will work best. The width of this wave guide should be chosen by considering the bow of the wafer. Indeed the second important design rule is to keep a bonding area big enough to have more adhesion energy than the elastic energy cost due to non flat wafers deformation.The adhesion energy is an important parameter of the direct bonding, as it is theenergy that drives the adhesion. This adhesion energy is different from the more widely known bonding energy which is the energy needed to separate two previously bonded wafers. In this work a simple method to measure the adhesion is proposed. Long time measurement of the evolution of the adhesion energy lead us to propose a mechanism for its evolution linked to the formation of capillary bridges between rough surfaces.

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy

As the miniaturization keeps decreasing in semiconductor device fabrication, metal contamination on silicon surfaces becomes critical. An investigation of the fundamental mechanism of metal contamination process on silicon surface is therefore important. Kinetics and thermodynamics of the copper out-plating process on silicon surfaces in diluted HF solutions are both evaluated by several analytical methods.