In this thesis, manufacturing of microirradiators, electrodeposition of radioactive elements such as Ni-63, and applications of these radioactive sources are discussed. Ni-63 has a half life of 100 years and a low energy beta electron of 67 keV, ideal for low dose low linear energy transfer (LET) research. The main focus of the research is on the novel Ni-63 microirradiator. It contains a small amount of total activity of radiation but a large flux, allowing the user to safely handle the microirradiator without extensive shielding. This thesis is divided into nine chapters. Properties of microirradiators and various competing radioactive sources are compared in the introduction (chapter 1). Detailed description of manufacturing Ni-63 microirradiator using the microelectrode as the starting point is outlined in chapter 2. The microelectrode is a 25 µm in diameter Pt disk sealed in a pulled 1 mm diameter borosilicate capillary tube, as a protruding wire or recessed disk microelectrode. The electrochemically active surface area of each is verified by cyclic voltammetry. Electrodeposition of nickel with a detailed description of formulation of the electrochemical bath in a cold "non-radioactive setting" was optimized by using parameters as defined by pourbaix diagrams, radioactive electroplating of Ni-63, and incorporation of safety regulations into electrodeposition. Calibration and characterization of the Ni-63 microirradiators as protruding wire and recessed disk microirradiators is presented in chapter 3. In chapters 4 through 6, applications of the Ni-63 microirradiators and wire sources are presented. Chapter 4 provides a radiobiological application of the recessed disk microirradiator and a modified flush microirradiator with osteosarcoma cancer cells. Cells were irradiated with 2000 to 1 Bq, and real time observations of DNA double strand breaks were observed. A novel benchtop detection system for the microirradiators is presented in chapter 5. Ni-63 is most commonly measured by liquid scintillation counters, which are expensive and not easily accessible within a benchtop setting. Results show liquid scintillation measurements overestimates the amount of radiation coming from the recessed disk. A novel 10 µCi Ni-63 electrochemically deposited wire acting as an ambient chemical ionization source for pharmaceutical tablets in mass spectrometry is in chapter 6. Typically, larger radioactive sources (15 mCi) of Ni-63 have been used in an ambient ionization scenario. Additionally, this is the first application of using Ni-63 to ionize in atmosphere pharmaceutical tablets, leading to a possible field portable device. In the last chapters, chapters 7 through 8, previous microirradiator experiments and future work are summarized. Chapter 7 illustrates the prototype of the electrochemically deposited microirradiator, the Te-125 microirradiator. In conjunction with Oak Ridge National Laboratory, Te-125m is a low dose x-ray emitting element determined to be the best first prototype of an electrochemically deposited microirradiator. Manufacturing, characterization, and experiments that were not successful leading to the development of the Ni-63 microirradiator are discussed. In chapter 8, future work is entailed in continuing on with this thesis project. The work presented in the thesis is concluded in chapter 9.

In this work, adhesion between electrolessly deposited copper and dielectric materials for use in microelectronic devices is investigated. The microelectronics industry requires continuous advances due to ever-evolving technology and the corresponding need for higher density substrates with smaller features. At the same time, adhesion must be maintained in order to preserve package reliability and mechanical performance. In order to meet these requirements two approaches were taken: smoothing the surface of traditional epoxy dielectric materials while maintaining adhesion, and increasing adhesion on advanced dielectric materials through chemical bonding and mechanical anchoring. It was found that NH3 plasma treatments can be effective for increasing both catalyst adsorption and adhesion across a range of materials. This adhesion is achieved through increased nitrogen content on the polymer surface, specifically N=C. This nitrogen interacts with the palladium catalyst particles to form chemical anchors between the polymer surface and the electroless copper layer without the need for roughness. Chemical bonding alone, however, did not enable sufficient adhesion but needed to be supplemented with mechanical anchoring. Traditional epoxy materials were treated with a swell and etch process to roughen the surface and create mechanical anchoring. This same process was found to be ineffective when used on advanced dielectric materials. In order to create controlled roughness on these surfaces a novel method was developed that utilized blends of traditional epoxy with the advanced materials. Finally, combined treatments of surface roughening followed by plasma treatments were utilized to create optimum interfaces between traditional or advanced dielectric materials and electroless copper. In these systems adhesion was measured over 0.5 N/mm with root-mean-square surface roughness as low as 15 nm. In addition, the individual contributions of chemical bonding and mechanical anchoring were identified. The plasma treatment conditions used in these experiments contributed up to 0.25 N/mm to adhesion through purely chemical bonding with minimal roughness generation. Mechanical anchoring accounted for the remainder of adhesion, 0.2-0.8 N/mm depending on the level of roughness created on the surface. Thus, optimized surfaces with very low surface roughness and adequate adhesion were achieved by sequential combination of roughness formation and chemical modifications.

abstract: Nickel-Copper metallization for silicon solar cells offers a cost effective alternative to traditional screen printed silver paste technology. The main objective of this work is to study the formation of nickel silicide contacts with and without native silicon dioxide SiO2. The effect of native SiO2 on the silicide formation has been studied using Raman spectroscopy, Rutherford backscattering spectrometry and sheet resistance measurements which shows that SiO 2 acts as a diffusion barrier for silicidation at low temperatures of 350°C. At 400°C the presence of SiO2 results in the increased formation of nickel mono-silicide phase with reduced thickness when compared to samples without any native oxide. Pre and post-anneal measurements of Suns Voc, photoluminescence and Illuminated lock in thermography show effect of annealing on electrical characteristics of the device. The presence of native oxide is found to prevent degradation of the solar cells when compared to cells without any native oxide. A process flow for fabricating silicon solar cells using light induced plating of nickel and copper with and without native oxide (SiO2) has been developed and cell results for devices fabricated on 156mm wafers have been discussed. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2016

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22068号 / 工博第4649号 / 新制||工||1725(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 邑瀬 邦明, 教授 宇田 哲也, 教授 杉村 博之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Strengthening, resistant and shielding properties, to name a few, can be achieved by implementing a surface material coating onto an engineering component. Various elements of these compounded parts can augment the functionality of the part, such as, increased life time and more interactive surfaces. Tungsten has proven to be a challenge to plate with other metals, but if done correctly, the results can allow for the cold spray of tungsten. Cold spraying tungsten particles alone provides a challenge because the powder is too hard and instead of adhering, it erodes the surface it is attempting to plate. Coating tungsten in a softer metal, like copper, will allow for the particles to adhere to the surface and create a strengthened and radiation shielded component. It also yields a better surface to electroplate onto in the future, as tungsten itself is hard to plate onto, so the copper layer provides the ability to easily plate other metals. The purpose of this thesis project is to encapsulate tungsten powder within copper, then scale up the process to produce bulk amounts of the material in a batch process. The particles will be encased using an electroplating method, that has been vi turned into a semi-autonomous process for the ease of producing bulk powder. While electroless deposition has previously shown positive results for attaining a uniform coating, making it a semi-batch process for bulk material would have an extreme cost in comparison to electrolytic deposition. The tungsten particles have been successfully enclosed in copper by electrolytic deposition in this set of experimentation using an HF electro-etch pretreatment and ultrasonic agitation during electroplating. Further experimentation will include improved methods of stirring and transferring powder, as the transfer takes too long between the etch and the onset of plating and the stirring method is bulky and reduces the area that can be efficiently plated on.

The thesis deals with the topic of silver coating on the inner surface of the tubes made of aluminum alloy EN AW-6101B. The high affinity of the aluminum for the oxygen, the heterogeneity of the surface and the presence of the hydrogen in the base material, are the properties which hinder the formation of metallic coating on the surface of the aluminum alloy. The saturation of the base material with the hydrogen, e.g. due to the pretreatment of the surface or by the process of creating of coatings, may under certain conditions cause the defects of the silver coating in the form of the bubbles (blisters). Other factors that may affect the quality of the silver coating are the way of creating of the interlayer and the conditions for the electrolytic deposition of the silver.

Engineered components can gain desirable properties when coated with surface materials. Wear-resistant coatings can improve the performance of contacting surfaces and allow for an extended life of the parts. Hard chromium has been the plating material of choice for certain wear and corrosion- resistant coatings because of its desirable combination of chemical resistance, adhesion, and mechanical properties. However, hexavalent chromium, a component of the process for applying hard chromium coatings, has been recognized by the EPA as having hazardous health and environmental impacts. Existing and planned environmental regulations restricts the use of process chemicals containing hexavalent chromium ions. This substantiates a need to develop an environmental friendly process for alternative coatings. Praxair has reported that Cr-Ni-C particles have a better corrosion resistance than current chromium carbide and nickel chromium powders. Today, Cr-Ni-C provides great qualities for flame spray and does not contain the toxic compounds used to deposit hard chromium, but is not compatible with application by cold spray. The purpose of this thesis project is to compare two processes for plating metal powder, chromium nickel carbide (Cr-Ni-C, CRC-410-1 from Praxair), with nickel. The particles were encapsulated using three different methods: one electroplating method previously used on particles, and two electroless plating processes using different solutions. The Cr-Ni-C particles were successfully encapsulated with Ni by one of the electroless deposition methods. The electrolytic deposition experiments did not yield the uniformity of coating without agglomeration that is being attained in industrial practice today. Further research on this method is recommended, due to the material operational cost in an industrial setting that is projected to be over 200 times cheaper than electroless deposition method. In the meantime, it should be possible to produce enough coated powder by electroless deposition to validate the utility of this coated powder in depositing wear- and corrosion-resistant coatings of Cr-Ni-C by cold spray.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2008. / Includes bibliographical references.

Recently, refractory materials have been proposed as a strong alternative to poly-silicon and aluminum alloys as metallization systems for Very Large Scale Integrated (VLSI) circuits because of their improved performance at smaller Integrated Circuit (IC) feature size and higher interconnect current densities. However, processing and reliability problems associated with the use of refractory materials have limited their widespread acceptance. The hot-wall low pressure chemical vapor deposition (LPCVD) of Molybdenum and Tungsten from their respective hexacarbonyl sources has been studied as a potential remedy to such problems, in addition to providing the potential for higher throughput and better step coverage. Using deposition chemistries based on carbonyl sources, Mo and W deposits have been characterized with respect to their electrical, mechanical, structural, and chemical properties as well as their compatibility with conventional IC processing. Excellent film step coverage and uniformity were obtained by low temperature (300-350 C) deposition at pressures of 400-600 mTorr. As-deposited films were observed to be amorphous, with a resistivity of 250 and 350 microohm-cm for Mo and W respectively. On annealing at high temperatures in a reducing or inert atmosphere, the films crystallize with attendant reduction in resistivity to 9.3 and 12 microohm-cm for Mo and W, respectively. The average grain size also increases as a function of time and temperature to a maximum of 2500-3000 A. The metals and their silicides that are deposited, using silane as silicon source, are integratable to form desired metal-silicide gate contact structures. Thus, use of the low resistivity of the elemental metal coupled with the oxidation resistance of its silicide manifests the quality and economy of the process. MOS capacitors with Mo and W as the gate material have been fabricated on n-type (100) silicon. A work function of 4.7 +/- 0.1 eV was measured by means of MOS capacitance-voltage techniques. The experimental results further indicate that the characteristics of W-gate MOS devices related to the charges in SiO₂ are comparable to those of poly-silicon; while, the resistivity is about two orders of magnitude lower than poly-silicon. It is therefore concluded that hot-wall low pressure chemical vapor deposition of Mo and W from their respective carbonyl sources is a viable technique for the deposition of reliable, high performance refractory metal/silicide contact and interconnect structures on very large scale integrated circuits.

A nonaqueous electroless deposition (ELD) coating process that uses a charge compensator in lieu of a ligand or complexing agent is presented. Si(100) coupons were hydroxylated using a sulfuric acid-hydrogen peroxide mixture (SPM or piranha). The surface was terminated with an amine group by immersion in a 5 mM solution of (3-aminopropyl)-trimethoxysilane (APTMS) in methanol followed by a 150°C anneal. Metal films were deposited by suspending samples in a bath made by dissolving Cu(II) chloride in ethylene glycol, which also served as the reducing agent, and adding 1-butyl-3-methylimidazolium tetrafluoroborate as a charge compensator. Annealing the coupons at 200°C in nitrogen promoted the formation of an electrically conductive thin film. Four-point probe measurements of the films yielded electrical conductivities in the range 10⁶-10⁷ S/m (10-80% of bulk conductivity). Electron microscopy images of the coated substrates showed a layer structure consisting of nanoparticles. The Cu particle core-ion shell complex is attracted to the positively charged amine groups at high pH depositing a thin metal particle film that is both continuous and conformal. With increasing ionic liquid concentration, film morphology changes from conformal films to discrete islands. In the ionic liquid concentration range from 2.0-2.5 mM, the metal films exhibit increased optical absorbance, luminescence and electrical conductivity. The film properties are correlated to interparticle interactions with electron imagery and spectroscopic ellipsometry. Lastly, a thin metal film was deposited that is both continuous and cohesive on the walls and floor of 5-10X aspect ratio trenches and vias.