The present work researches influence of energy focusing effect to the fusion zone defects in the electron beam welding, which include fusion zone shape, welding depth, welding width, rippling and spiking. And to verify the model of welding defects base on theory and experiment. A spike is a sudden increase in penetration beyond what might be called the average penetration line. Many spikes have voids and cold shuts in their lower portions, because molten metal does not fill in completely, producing a condition similar to a cold shut in a casting. Ripples on a workpiece surface are generally associated with segregation, porosity and other microstructure defects. These become the objectives in this project.

The microelectronics industry is driven by the need to produce smaller transistors at lower costs, and this requires an ever-changing approach to the chemistry involved in their fabrication. While photolithography has been able to keep pace with Moore’s law over the past four decades, alternative patterning technologies are now receiving increased attention to keep up with market demand. The first project describes work towards increasing the sensitivity of electron-beam resists by incorporating electron-withdrawing groups into the alpha position of methacrylates. After monomer design and synthesis, several polymers were synthesized that investigated the role of fluorine in the resists performance. G-values, electron-beam contrast curves, and EUV imaging showed that these fluorinated polymethacrylates outperformed current industrial resists. The next project deals with the design, synthesis, and evaluation of a resist that seeks to decouple chemical amplification from acid diffusion. While work was shown that a system comprised of a photo-labile polyphthalaldehyde and x novolak could achieve this process, the high dose required to image was problematic. An aliphatic dialdehyde was envisioned to account for these issues, but its synthesis was never achieved. A polyethylene glycol aldehyde was synthesized and polymerized, but its material properties did not perform the intended function. Ultimately, the stability of aliphatic aldehydes proved to be too unstable for this project to continue. While the synthesis was troublesome, a fundamental study of ceiling temperatures was undertaken. Numerical and analytical solutions were developed that describe the exact nature of the equilibrium constant on a living polymer system. These results were verified by a VT-NMR experiment, which accurately predicted the ceiling temperature of polythalaldehyde with a Van’t Hoff plot. Lastly, the self-assembly of block copolymers was investigated as a means to produce high resolution, high density nano-imprint lithography templates for bit patterned media. The first set of experiments involved synthesizing polymeric cross-linked surface treatments from substituted styrenes. The aryl substituent was shown to largely effect the surface energy, and after anionically synthesizing PS-b-PMMA, these materials were shown to effect block copolymer orientation. To produce a 3-D pattern of the self-assembled features, silicon was incorporated into one block to provide adequate etch resistance. Several monomers were investigated, and two, an isoprene and methacrylate analog, were successfully incorporated into two block copolymers. The silicon containing methacrylate derivative polymer was shown to successfully self-assemble in thin films under solvent annealing conditions. / text

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Wireless Surface Acoustic Wave (SAW) devices were fabricated and tested using planar Lithium Niobate (LiNbO₃) as substrate. The working frequencies were in the 180 MHz and 360 MHz range. Using a network analyser, the devices were interrogated with a wireless range of more than 2 metres. Trials with Electron Beam Lithography (EBL) to fabricate SAW devices working in the 2450 MHz with a calculated feature size of 350 nm are discussed. Charging problems became evident as LiNbO₃ is a strong piezoelectric and pyroelectric material. Various attempts were undertaken to neutralise the charging problems. Further investigation revealed that sputtered Zinc Oxide (ZnO) is a suitable material for attaching SAW devices on irregularly shaped material. DC sputtering was used and several parameters have been optimised to achieve the desired piezoelectric effect. ZnO was sputtered using a magnetron sputtering system with a 75 mm Zn target and a DC sputter power of 250 Watts. Several trials were performed and an optimised material has been prepared under the following conditions: 9 sccm of Oxygen and 6 sccm of Argon were introduced during the process which resulted in a process pressure of 1.2x10⁻² mbar. The coatings have been characterised using Rutherford Backscattering, X-ray diffraction, SEM imaging, and Atomic force microscopy. SAW devices were fabricated and tested on 600 nm thick sputtered ZnO on a Si substrate with a working frequency of 430 MHz. The phase velocity has been calculated as 4300m/s. Non-planar samples have been coated with 500 nm of sputtered ZnO and SAW structures have been fabricated on using EBL. The design frequency is 2450 MHz, with a calculated feature size of 1 µm. The surface roughness however prevented a successful lift-off. AFM imaging confirmed a surface roughness in the order of 20 nm. Ways to improve manufacturability on these samples have been identified.

In thin film fabrication, growth of high quality thin films with reproducibile properties is one of the main challenges. In order to achieve this goal, the influnce of the deposition system control parameters on film properties must be studied. This can be a complex process since many parameters may need to be considered. In this thesis, the electron beam evaporation of thin aluminum oxide films was investigated. Films were deposited with and without oxygen supply in the chamber, and at various ebeam source settings. A Varialble Angle Spectroscopic Ellipsometry system was used to characterize the films. Refractive index, which depends on material density and stoichiometry, was used as the figure of merit. It was observed that refractive index increases with deposition rate. Refractive index also changes with oxygen pressure and upon exposure to air. Various models to explain this behaviour are proposed and discussed. / Materials Engineering

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Texas State University--San Marcos, 2008. / Vita. Includes bibliographical references (leaves 50-51). Also available on microfilm.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 112-114).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 169-171). Available also in a digital version from Dissertation Abstracts.