The objective of the thesis is to investigate applicability of high pulse repetition rate picosecond lasers for microfabrication and to clarify high repetition rate pulse interaction with metals and silicon. The ablation threshold and accumulation rate dependence on the laser pulse duration for silicon and metals has been experimentally studied. The model of optimal focus conditions for the maximum ablation rate was developed and experimentally confirmed. The material evaporation rate decreases duo to plasma screening for high pulse energies. Various pulse length lasers have been used for cutting and drilling of silicon. In this work key properties of laser radiation, radiation absorption, ablation and plasma formation are discussed. Surface spectroscopy methods have shown that laser cutting of silicon in the air leads to the cut surface doping with carbon atoms up to 5 µm depth from carbon dioxide in the atmosphere, and the resulting silicon carbide influences the laser cut quality. Testing of applicability of high pulse repetition rate picosecond lasers for the production of complex shapes, relationships between surface roughness and process parameters were determined. Heat abstraction from the workpiece, during laser cutting of stents from nitinol, limits the potential use of the average laser power and the effective cutting speed The silver and gold picosecond laser ablation in the liquid medium generates a narrow size distribution of nanoparticles, which form a stable... [to full text] / Disertacijos tikslas yra ištirti didelio impulsų pasikartojimo dažnio pikosekundinių lazerių pritaikomumą medžiagų mikroapdirbimui, bei išaiškinti tokių lazerių spinduliuotės sąveikos su metalais ir siliciu ypatybes. Eksperimentiškai buvo ištirta abliacijos slenksčio ir akumuliacijos koeficiento priklausomybė nuo lazerio impulso trukmės siliciui ir metalams. Sukurtas ir eksperimentiškai patvirtintas modelis optimalioms fokusavimo sąlygoms surasti, siekiant maksimalios abliacijos spartos. Didelei impulso energijai, medžiagos nugarinimo efektyvumas mažėja dėl ekranuojančio plazmos poveikio. Įvairių impulso trukmių lazeriai buvo panaudoti silicio gręžimui bei pjovimui. Paviršiaus spektroskopijos metodais, nustatyta, kad pjovimo metu silicis yra legiruojamas anglimi iki 5 µm gylio iš atmosferoje esančio anglies dvideginio, o susidariusi silicio karbido fazė įtakoja lazerinio pjovimo kokybę silicio bandinio gylyje. Taikant didelio impulsų pasikartojimo dažnio pikosekundinius lazerius sudėtingos formos detalių gamybai, rasti sąryšiai tarp paviršiaus šiurkštumo bei proceso parametrų. Pjaunant lazeriu stentus iš Nitinolio, šilumos nukreipimas nuo ruošinio riboja galimą panaudoti lazerio vidutinę galią ir tuo pačiu pasiekiamą efektyvųjį pjovimo greitį; Vykdant sidabro ir aukso abliaciją pikosekundiniu lazeriu skystyje, generuojamos siauro dydžių skirstinio nanodalelės, kurios sudaro stabilius koloidinius tirpalus.

here is an increasing demand for higher bandwidth (BW) between logic and memory ICs for future smart mobile systems. Such high BW are proposed to be achieved using 3D interposers that have ultra-small through-package-via (TPVs) interconnections to connect the logic device on one side of the interposer to the memory on the other side. The current approach is primarily based on organic or silicon interposers. However, organic interposers face several challenges due to their poor dimensional stability, and coefficient of thermal expansion (CTE) mismatch to silicon ICs. Silicon interposers made with back-end-of-line (BEOL) wafer processes can achieve the required wiring and I/O density, but are not cost effective, and in addition exhibit higher electrical loss due to the semiconducting nature of the Si substrate. In this research, ultra-thin 3D Glass Interposers are studied as a superior alternative to organic and silicon interposers. The fundamental focus of this research is to achieve ultra-small TPVs in thin glass with dimensions similar to that of through-silicon-vias (TSVs) in silicon. The objective of this research is to study and demonstrate ultra-small pitch (30µm) TPV hole formation (10µm diameter), metallization and electrical characterization in ultra-thin (30µm) glass substrates. To meet these objectives, this study focusses on four main research tasks: a) electrical modeling and design of ultra-small TPVs in glass, b) small diameter TPV hole formation with minimum defects, c) copper metallization of TPVs with reliable adhesion, and d) electrical characterization of TPVs. This research reports the first demonstration of ultra-small TPVs (10-15µm in diameter) in ultra-thin glass interposer substrates (30µm). A thin-glass handling method is developed using polymer surface layers to achieve defect-free handling of glass even at thicknesses as low as 30µm. Several TPV formation methods are explored including excimer laser ablation using 193nm (ArF) lasers to form TPVs with smallest diameter and pitch. A brief study on the through-put capabilities of these excimer lasers is also discussed. The fundamental approach to TPV metallization involves a semi-additive-plating process (SAP) using electroless and electrolytic copper deposition techniques. The resulting side-wall surfaces of TPVs after metallization are analyzed through SEM imaging of TPV cross-sections, and are further characterized using nano-indentation tests. Additionally, thermo-mechanical reliability tests and failure analysis are performed to study the reliability of TPVs that are metallized with Cu. This research culminates in design, fabrication and electrical characterization of small pitch TPVs in ultra-thin glass interposers (30µm).

The objective of this thesis work is to increase the functionality of optical fibers for possible applications in life-sciences. Optical fibers are a promising technology for use in biology and medicine. They are low-costwaveguides, flexible and have a small cross-section. They can guide high-power light with low loss in a micrometer core-size. These features make fibers attractive for minimally-invasive,in-vivostudies. The backwards guidance of the optical signal allows for real-time monitoring of the distance to the scattering targets and to study the environment through Raman scattering and fluorescence excitation. The longitudinal holes introduced in the fibers can be used,for instance,for delivery of medicine to a specific regionof a body. They could even be used for the extractionof species considered interesting for further analysis, for example, studyingcells that may be cancer-related. This thesis deals with four main topics. First, a demonstration is presented of the combination of high-power light guidance for ablation, low-power light reflectometry for positioning, and for liquid retrieval in a single fiber. It was found that in order to exploit the microfluidic possibilities available in optical fibers with holes, one needs to be able to combine fluids and light in a fiber without hindering the low-loss light guidance and the fluid flow. Secondly, one should also be able to couple light into the liquids and backout again. This is the subject of another paper in the present thesis. It was also observed that laser excitation through a fiber for the collection of a low-intensity fluorescence signal was often affected by the luminescence noise createdby the primary-coating of the fiber. This problem makes it difficult to measure low light-levels, for example, from single-cells. Athirdpaper in this thesis then describes a novel approach to reduce the luminescence from the polymer coating of the fiber, with the use of a nanometer-thick carbon layer on the cladding surface. Finally, exploiting some of the results described earlier, an optical fiber with longitudinal holes is used for the excitation, identification and for the collection of particles considered being of interest. The excitation light is guided in the fiber, the identification is performed by choosing the fluorescent particles with the appropriate wavelength, and, when a particle of interest is sufficiently near the fiber-tip, the suction system is activated for collection of the particle with good specificity. It is believed that the work described in this thesis could open the doors for applications in life-sciences and the future use of optical fibers for in-vivo studies. / <p>QC 20140516</p>

Although the benefits of ICP-MS are well documented, the determination of analytes at low levels in high concentrations of matrix elements has proved difficult. As ICP-MS is a 'flow into' instrument the deposition of salts throughout the system is a common cause of significant loss of signal. The application of desolvation of aluminosilicate samples, to aid in the production of more robust plasma conditions, was investigated to increase the efficiency of the ICP in processing the sample. The performance of the ICP-MS was monitored with different cone arrangements and by running the skimmer cones at elevated temperatures. An alternative to modification of the instrument is to employ chemical modification of the sample and hence the separation of Au and Pt from an aluminosilicate matrix via the use of solid phase extraction (SPE) columns were investigated as a means of dealing with high levels of dissolved solids. OVB based SPE columns were found to give high retentions of Au and Pt when chelated with ammonium pyrrolidinediethylcarbamate (APOC). A second alternative that avoided digestion of the aluminosilicate matrices, was to carry out the analysis using laser ablation (LA). LA-ICP-MS is becoming increasingly used for trace elemental analysis but as yet no universal calibration method is available. The general problems associated with matrix matched standards are inherent as the ablation mechanism and plasma conditions can differ dramatically with very small changes in matrix composition. Hence the addition of chromophores was employed to increase the absorption of the laser energy. The use of vanillic, nicotinic and pyrazinoic acid were used to improve the ablation of pressed powder discs at the laser wavelength of 213 nm. Synthetic aluminosilicate discs and standard additions were both employed for the calibration and determination of Ti.

Novel techniques for in-situ lead isotope analysis of melt inclusions using multicollector inductively coupled plasma mass spectrometry, and parallel Faraday cup and ion counter detection have been developed. These provide for measurement of the critical 204Pb isotope, which has been unavailable in melt inclusion Pb isotope studies, but requires on-line determination of 200Hg to correct for 204Hg isobaric interferences. External standardisation allows for effective mass fractionation correction and ion counter gain calibration. An off-line Tau correction was applied and standard glass analyses suggest that this correction provides more accurate and precise results.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Melbourne, School of Earth Sciences, 2006. / Typescript. Includes bibliographical references (leaves 179-193).

Thesis (Ph. D.)--University of Alabama at Birmingham, 2006. / Additional advisors: Andrei V. Stanishevsky, Derrick R. Dean, Gregg M. Janowski, Yogesh K. Vohra. Description based on contents viewed Feb. 11, 2009; title from PDF t.p. Includes bibliographical references (p. 132-151).

Thesis (Ph. D. in Biomedical Engineering)--Vanderbilt University, Dec. 2004. / Title from title screen. Includes bibliographical references.

Thesis (M. Sc.), Memorial University of Newfoundland, 1999. / Includes bibliographical references.