Marburg, Universiẗat, Diss., 2000.

A method was proposed for the fabrication of air-gaps embedded in dielectric layers using thermally decomposable sacrificial polymers. The research had two main objectives: (1) the development and characterization of air-gap fabrication for use in a wide spectrum of applications; and (2) the integration of air-gaps into a specific application: air-gaps in an integrated circuit compliant wafer level packaging technology, Sea of Leads. Polynorbornene and polycarbonate sacrificial materials were used to form air-gaps at temperatures of 200, 300, and 400oC. Fabrication results of air-gaps encapsulated by both inorganic and organic dielectric materials indicated that the thermal and mechanical properties of the dielectric materials at the decomposition temperature of the sacrificial material resulted in success or failure of the process. Multi-layered encapsulating materials enabled the use of a dielectric material which does not successfully form air-gaps on its own. Thermal decomposition of the sacrificial materials with alteration in the polymer chemistry was studied. Polynorbornene containing 90 mol% butyl and 10 mol% triethoxysilyl side groups was selected as an optimum 400oC decomposition temperature material. The decomposition of this polynobornene composition in an open nitrogen atmosphere was contrasted to decomposition of the polynorbornene while completely encapsulated in a dielectric material. Thermogravimetric analysis and examination of residual surfaces following the decomposition, combined with comparison of the overall kinetic parameters of the decomposition reaction, indicated differences in the two overall processes. The design concept of Sea of Leads three-dimensionally compliant packaging technology with embedded air-gaps is presented. The critical issues resulting from the addition of air-gaps into the process are the compatibility of materials, lithography on topographical features, and yield and uniformity. Factors influencing the z-axis mechanical performance of the air-gap were determined to be the air-gap shape and size, the encapsulating material dielectric properties and thickness, and the decomposition conditions. Model calculations combined with the known limitations of fabrication provided a design space for maximum out-of-plane mechanical movement and compliance of the air-gaps. The results demonstrated that the incorporation of an embedded air-gap in Sea of Leads technology can achieve the necessary z-axis compliance goals for future applications.

Permanent dielectric materials are integral to the fabrication of microelectronic devices and packaging. Dielectrics are used throughout devices to electrically and mechanically isolate conductive components. As such, they are required to have low electrical permittivity and robust mechanical properties. For packaging applications, dielectrics can be directly photo-definable. Dielectrics need to have excellent lithographic properties. These properties are pivotal for enabling high yield and low cost fabrication of reliable, energy efficient devices. The aim of this work was to develop new positive tone dielectrics which have improved or application-specific lithographic, mechanical, and electrical properties. To this end, several new dielectric polymers and chemistries were evaluated and characterized. Initially, it was desired to develop a positive tone, polynorbornene (PNB) dielectric that utilizes diazonaphthoquinone (DNQ) photochemistry. Cross-linking was achieved with epoxy cross-linkers during a thermal cure. Several DNQ-containing compounds were evaluated, but only one had good miscibility with PNB. The dissolution characteristics of PNB were measured with respect to polymer composition, DNQ loading, and cross-linker loading. PNB films exhibited unique dissolution properties, and these measurements allowed for an optimum formulation to be developed. A formulation with 20 pphr DNQ and 10 pphr epoxy cross-linker had sufficient inhibition in unexposed regions and fast dissolution in exposed regions. The resulting dielectric was the first positive tone, DNQ-based PNB dielectric. After achieving photo-definability, the cross-linking of the cured dielectric was evaluated by characterizing the mechanical properties. It was discovered that DNQ acted as a cross-linker in these films, and this insight was key to achieving good curing of the dielectric. Several experiments were performed to support this conclusions, and the reaction kinetics of this cross-linking reaction were evaluated. This effort produced a functional, positive tone dielectric with a sensitivity of 408 mJ cm-2 and contrast of 2.3. The modulus was 2.0 to 2.6 GPa and the dielectric constant of 3.7 to 3.9, depending on the curing conditions. The DNQ cross-linking results led to the investigation of other cross-linking chemistries for positive tone dielectrics. A chemically amplified (CA) photochemistry was utilized along with a Fischer esterification cross-linking reaction. Patterning and cross-linking were demonstrated with a methacrylate polymer. Successful positive tone lithography was demonstrated at a high sensitivity of 32.4 mJ cm-2 and contrast of 5.2. Cross-linking was achieved at 120°C as shown by residual stress and solubility measurements. The CA photochemistry and Fischer esterification cross-linking were also demonstrated using a PNB dielectric, which was shown to have improved lithographic properties: a sensitivity of 8.09 mJ cm-2 and contrast of ≥ 14.2. Work was performed to evaluate the effect of the polymer composition on the mechanical and electrical properties. A polymer with 60 mol% hexafluoroisopropanol norbornene and 40 mol% tert-butyl ester norbornene exhibited a dielectric constant of 2.78, which is lower than existing positive tone dielectrics. It also outperformed existing dielectrics in several other categories, including dark erosion, volume change, cure temperature, and in-plane coefficient of thermal expansion. However, a limitation of this dielectric was cracking in thick films. The final study was to improve the mechanical properties of this CA PNB dielectric specifically to enable 5 µm thick films. First, a terpolymer was tested that included a non-functional third monomer. The dielectric constant increased to 3.48 with 24 mol% of the third monomer. Second, low molecular weight additives were used to lower the modulus. Only one of the five tested additives enabled high quality, thick films. This additive did not significantly affect the dielectric constant at low loadings. An optimized formulation was made, and processing parameters were studied. The additive decreased the lithographic properties, lowering the sensitivity to 175 mJ cm-2 and lowering the contrast to 4.36. In all, this work produced three functional dielectrics with positive tone photo-definability and good lithographic properties. Each dielectric can serve a variety of purposes in microelectronics packaging.

Stimuli-responsive materials are changing the landscape of actuated materials, optoelectronics, molecular machines, solar cells, temporary memory storage, and biomedical materials. Specifically, photo-responsive polymers have gained acceleration in research and application since the last two decades in the form of a surface coating and micro-patterns. Light as a stimulus can be coherent, mono or polychromatic, tunable for power (intensity) and energy (wavelength), and has precise spatiotemporal control. Conventional surface coating techniques such as spin coating are unable to impart properties to the coatings in terms of sturdiness, homogeneity, uniformity over the complex surface, post deposition modification, and process efficiency. Also, in the field of photoreponsive polymers, there is no simple technique for surface-patterning of photo-responsive polymers, which is an important missing link between current research and future potential applications. This dissertation designs new strategies for light-mediated ring opening metathesis polymerization (ROMP) to synthesize a diverse class of stable photo-responsive polymers and coatings. Firstly, we propose a new synthetic route to functionalize surface-initiated ring opening metathesis polymerization (SI ROMP) coatings. The backbone of ROMP polymers has internal carbon-carbon double bonds which are potential sites to introduce additional functionalities like stimuli-responsive functional groups. We leverage these unsaturated bonds to incorporate functionalized side chains using thiol-ene click chemistry. Thiol-ene chemistry is a versatile approach to attach diverse functional groups at the site of a carbon-carbon double bond. This approach was tested by grafting 3 types of thiols with different functional tail groups and can be readily used for any polyolefin coatings. Secondly, oxidative degradation of SI ROMP coatings in the organic solvent is a common problem resulting in a decrease in the film thickness due to polymer chain cleavage. We incorporated a custom designed crosslinker to the polynorbornene (pNB) coatings to prepare in situ crosslinked pNB coatings. This approach provides a crosslinked coating of pNB with significantly increased stability against organic solvents by decreasing the film loss from 73 % to 28 %. Lastly, a novel approach of making photo-responsive polymer by light mediated ROMP is demonstrated. Light mediated control over rate of polymerization is the key feature required for patterning surface with photoresponsive polymers. We achieved this goal by designing and synthesizing a monomer that effectively controls the activity of the catalyst by temporarily deactivating it on irradiation with UV 365 nm light and reactivating it back by irradiation with blue 455 nm light to resume the ROMP.

No description available.

No description available.

Universiẗat, Diss., 2004--Düsseldorf.

No description available.

La délivrance contrôlée de médicaments constitue un enjeu thérapeutique de première importance pour le milieu médical. Elle doit, en effet, permettre de diminuer la toxicité du médicament en limitant sa concentration dans l'organisme et en ciblant son lieu de délivrance. Ce projet de recherche a conduit à la réalisation de nouveaux nano-vecteurs particulaires utilisables pour la délivrance de médicaments par hyperthermie locale. Ces objets sont constitués d'un cœur de polynorbornène et d’une écorce de poly (oxyde d’éthylène) et sont synthétisés par polymérisation par ouverture de cycle de type métathèse (ROMP) en dispersion. L’acide salicylique est encapsulé dans ces particules en tant que molécule modèle. L'originalité de ce sujet pluridisciplinaire réside : dans la nature de la particule, qui permet une libération du principe actif à partir de 35-45°C et dans la technique d'imprégnation des particules par la voie fluide supercritique. / Controlled release systems are attracting increasing interest because of their potential application in biomedical field. Indeed, such systems should enable to lower toxicity of medicines by targeting the therapeutic action and by limiting the concentration of drugs in the organism. In this research project, new nanoparticles have been developed for a thermosensitive control of drugs’ delivery. These particles consist of a polynorbornene core and a polyethylene oxide shell and are developed by dispersion ring opening metathesis polymerization. As a model drug, salicylic acid has been encapsulated in those core-shell materials. This multidisciplinary project is original for two reasons. On the one hand, the nature of the particle which enables to release the drug from 35-45°C. On the other hand, the encapsulation technique that has been chosen is the impregnation under supercritical carbon dioxide.