La fonctionnalisation de la surface du verre par des molécules organiques permet de modifier son énergie de surface ou d’améliorer l’adhésion d’un revêtement. La méthode classique de fonctionnalisation directe du verre repose sur une réaction de silanisation, via la formation de ponts siloxanes Si O Si. Ces ponts ont tendance à s’hydrolyser en milieu salin ou alcalin, entrainant la perte de la fonctionnalité du verre. Une solution envisagée consiste à déposer une couche de nitrure de silicium (SixN4) sur le verre, permettant de greffer des molécules organiques via des liaisons covalentes robustes : Si C ou N C. Le nitrure de silicium présente l’avantage d’être un matériau très souvent utilisé dans l’industrie verrière en raison de sa capacité à bloquer la diffusion des ions sodium et de protéger ainsi le verre de la corrosion.L’objectif de ce travail de thèse est de caractériser et contrôler la surface du nitrure de silicium, puis d’optimiser et de comprendre la modification de sa surface par le greffage covalent de molécules organiques.Lorsque le nitrure de silicium est exposé à l’air, une couche d’oxynitrure est formée en surface. L’optimisation et la compréhension du décapage de cette couche d’oxynitrure natif en milieu liquide est l’objet de la première phase de ce travail. La composition chimique de la surface est finement caractérisée et quantifiée en combinant des mesures de spectroscopie infrarouge en mode de réflexion totale atténuée (IR-ATR), de spectroscopie de photoélectrons X (XPS) et des dosages chimiques de surface. Le décapage dans des solutions fluorées (HF et NH4F) permet de retirer efficacement la couche d’oxynitrure et laisse majoritairement en surface des liaisons Si-F et dans une moindre mesure des liaisons N H et Si OH. La composition chimique de la surface peut toutefois être modifiée pour former des groupements Si H, soit en enrichissant la couche du SixN4 en silicium, soit en soumettant la surface à un traitement par plasma d’hydrogène à l’issue du décapage. A partir des observations expérimentales, une proposition décrivant les mécanismes mis en jeu lors du décapage est présentée.Dans la seconde partie de la thèse, la surface du nitrure de silicium est modifiée par l’immobilisation de molécules organiques, plus spécifiquement par la réaction d’un 1 alcène sous activation thermique ou photochimique. La composition chimique de la surface et les conditions d’activation de la réaction modifient la réaction de greffage et la densité des couches organiques. En particulier, la présence de liaisons Si-H et l’enrichissement de la couche en silicium sont étudiés en détail. Dans une dernière partie, dans une visée plus applicative, des couches denses fluorées présentant un caractère hydrophobe naturel sont greffées sur la surface du nitrure de silicium. / Covalent grafting of organic molecules on glass can modify its surface physico-chemical properties or improve the adhesion of a coating. Such a functionalization usually relies on a silanisation reaction, bonding molecules to the surface through Si-O-Si bonds. Unfortunately, the resulting molecular layers do not exhibit long-term stability due to the hydrolysis of siloxane groups. One solution would consist in depositing a silicon nitride layer on glass, allowing the glass surface to be functionalized through more stable bonds N-C or Si-C. Silicon nitride layers are frequently used in glass industry. They are well-known for their durability properties and are often used as a protective layer against glass corrosion.The aim of this project is to characterize and control the non-oxidized silicon nitride surface, then to optimize and understand the surface modification by covalent grafting of organic molecules.When silicon nitride is exposed to atmosphere, an oxynitride layer is formed on its surface. Several efficient ways to remove this native oxynitride are first studied and optimized. The quantitative characterization and control of the surface chemical composition provide a reliable starting point for the functionalization step. The surface chemical composition is quantitatively investigated by combining Attenuated Total Reflection InfraRed spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and chemical dosing. The etching in HF-based solutions efficiently removes the oxynitride layer and leads to a surface mainly covered with Si-F bonds and smaller amounts of Si-OH and N-H bonds. The surface composition can be modified by a H2 plasma treatment performed after the wet etching or by changing the silicon nitride layer composition (silicon enrichment), leading in either case to the formation of Si-H bonds on surface. An etching mechanism is suggested from these experimental observations.The second part of this work is focused on the grafting of the alkyl chains on the silicon nitride surface. The surface is reacted with a 1-alkene, using photochemical or thermal activation. The grafting efficiency depends on the surface composition and the activation conditions. The presence of surface Si-H bonds and the effect of Si enrichment are considered in details. In a final part, in an applicative view, functional hydrophobic molecules are grafted on the silicon nitride surface.

As multistep, multilayer processing in semiconductor industry becomes more complex, the role of cleaning solutions and etching chemistries are becoming important in enhancing yield and in reducing defects. This thesis demonstrates successful formulations that exhibit copper and tungsten compatibility, and are capable of Inter Layer Dielectric (ILD) cleaning and selective Ti etching. The corrosion behavior of electrochemically deposited copper thin films in deareated and non-dearated cleaning solution containing hydrofluoric acid (HF) has been investigated. Potentiodynamic polarization experiments were carried out to determine active, active-passive, passive, and transpassive regions. Corrosion rates were calculated from tafel slopes. ICP-MS and potentiodynamic methods yielded comparable Cu dissolution rates. Interestingly, the presence of hydrogen peroxide in the cleaning solution led to more than an order of magnitude suppression of copper dissolution rate. We ascribe this phenomenon to the formation of interfacial CuO which dissolves at slower rate in dilute HF. A kinetic scheme involving cathodic reduction of oxygen and anodic oxidation of Cu0 and Cu+1 is proposed. It was determined that the reaction order kinetics is first order with respect to both HF and oxygen concentrations. The learnings from copper corrosion studies were leveraged to develop a wet etch/clean formulation for selective titanium etching. The introduction of titanium hard-mask (HM) for dual damascene patterning of copper interconnects created a unique application in selective wet etch chemistry. A formulation that addresses the selectivity requirements was not available and was developed during the course of this dissertation. This chemical formulation selectively strips Ti HM film and removes post plasma etch polymer/residue while suppressing the etch rate of tungsten, copper, silicon oxide, silicon carbide, silicon nitride, and carbon doped silicon oxide. Ti etching selectivity exceeding three orders of magnitude was realized. Surprisingly, it exploits the use of HF, a chemical well known for its SiO2 etching ability, along with a silicon precursor to protect SiO2. The ability to selectively etch the Ti HM without impacting key transistor/interconnect components has enabled advanced process technology nodes of today and beyond. This environmentally friendly formulation is now employed in production of advanced high-performance microprocessors and produced in a 3000 gallon reactor.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17788号 / 工博第3767号 / 新制||工||1576(附属図書館) / 30595 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 木村 健二, 教授 立花 明知 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24580号 / 工博第5086号 / 新制||工||1974(附属図書館) / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 江利口 浩二, 教授 土屋 智由, 教授 平方 寛之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

This dissertation presents research on the fabrication of optofluidic sensor platforms, which consist of integrated hollow waveguides and solid waveguides. Antiresonant reflecting optical waveguides (ARROWs) filled with liquids or gases, can be used for high-sensitivity sensing in applications of biotechnology, chemical synthesis, and analytical chemistry. The fabrication method developed for integrated ARROW sensing platforms utilizes standard microfabrication processes and materials. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD) or sputtering. A sacrificial material is then patterned over the bottom cladding layers by photolithography. Additional dielectric layers are deposited around the core, forming the structure of the waveguides. Integrated solid-core waveguides can be easily created by etching a ridge into the topmost dielectric cladding layer. The hollow core waveguides are then formed by wet etching the sacrificial core material. The coupling efficiency between solid core and hollow core waveguides is extremely important for the platform's overall sensitivity. Efficiencies can be enhanced from 18% to 67% by adjusting the thickness of the thick top oxide. Experimental results prove that optical throughput was improved by 17.1× with this improved interface transmission. Sputtered films were investigated as an alternative to for producing cladding layers. The experimental results reveal that sputtered layers show poor adhesion and mechanical strength which make them unreliable for hollow waveguides with small dimension. High-sensitivity ARROW platforms were obtained by employing hybrid layers (PECVD SiO2 and sputtered Ta2O5) as claddings and building waveguides on self-aligned pedestals. The photolumiscence background was only 1/10 that of previous devices made with SiO2/SiN and the average signal-to-noise ratio was improved by 12×.

The purpose of this thesis was to study and to document the life and work of Mahonri Young as a printmaker. The more specific questions to be answered in this study were: 1. How does Mr. Young rate as a fine printmaker? 2. What are his contributions to American Art as a fine printmaker?

A scanning Fabry-Perot transmission filter composed of a pair of dielectric mirrors has been demonstrated at millimeter and sub-millimeter wavelengths. The mirrors are formed by alternating quarter-wave optical thicknesses of silicon and air in the usual Bragg configuration. Detailed theoretical considerations are presented for determining the optimum design including factors that affect achievable finesse. Fundamental loss by lattice and free carrier absorption are considered. High resistivity in the silicon layers was found important for achieving high transmittance and finesse, especially at the longer wavelengths. Also considered are technological factors such as surface roughness, bowing, and misalignment for various proposed manufacturing schemes. Characterization was performed at sub-mm wavelengths using a gas laser together with a Golay cell detector and at millimeter wavelengths using a backward wave oscillator and microwave power meter. A finesse value of 422 for a scanning Fabry-Perot cavity composed of three-period Bragg mirrors was experimentally demonstrated. Finesse values of several thousand are considered to be within reach. This suggests the possibility of a compact terahertz Fabry-Perot spectrometer that can operate in low resonance order to realize high free spectral range while simultaneously achieving a high spectral resolution. Such a device is directly suitable for airborne/satellite and man-portable sensing instrumentation.

This thesis covers the design, fabrication, modeling and characterization of electrostatically actuated silicon membranes, with applications to microelectromechanical systems (MEMS). A microfabrication process was designed to realize thin membranes etched into a silicon wafer using a wet anisotropic etching process. These flexible membranes were bonded to a rigid counterelectrode using a photo-patterned gap layer. The membranes were actuated electrostatically by applying a voltage bias across the electrode gap formed by the membrane and the counterelectrode, causing the membrane to deflect towards the counterelectrode. This deflection was characterized for a range of actuating voltages and these results were compared to the deflections predicted by calculations and Finite Element Analysis (FEA). This thesis demonstrates the first electrostatically actuated MEMS device fabricated in the Cal Poly, San Luis Obispo Microfabrication Facility. Furthermore, this thesis should serve as groundwork for students who wish to improve upon the microfabrication processes presented herein, or who wish to fabricate thin silicon structures or electrostatically actuated MEMS structures of their own.

No description available.