<p>Examensarbetets mål är att rengöra en diamantkomposit med en ytrengöringsmetod. Metoden skulle vara mera effektiv än den manuella sandblästring som används idag för att ytrengöra detaljen.</p><p>Detaljen är liten och har ett vitalt spår som ska rengöras. Detta ställer höga krav på effektiva metoder. De metoder som tas upp teoretiskt i examensarbetet är bland annat blästring, trumling och laserrengöring. Ett urval av metoderna testades. Den metod som utmärkte sig främst I testerna var automatisksandblästring. Det gav lika bra resultat som manuell sandblästring men på en bråkdel av tiden som det tog för manuellsandblästring. Det gjordes även en investeringsberäkning i examensarbetet och den gav att trumling var den billigaste metoden.</p><p>Slutsatsen är att automatisk sandblästring bör användas som metod. Metoden gav ett bättre resultat än övriga metoder och var mindre arbetskrävande än manuell sandblästring.</p> / <p>This goal of the thesis´ is to surface finish a diamond with an appropriate method. The method should be more effective than manual sandblasting, the current method in use. The part is small and it has a vital track that must be surface cleaned. This puts great demands on effective methods. The methods that are mentioned theoretically in the thesis are automatic sandblasting, tumbling and laser cleaning. A couple of methods were tested and evaluated. Automatic sandblasting was found to be most effective. That method gave an equal result compared to the manual sandblasting but with a fraction of the time compared to manual sandblasting. Within the thesis a capital budgeting have been done.</p><p>The conclusion of the thesis was that the automatic sandblasting machine should be used.</p>

Examensarbetets mål är att rengöra en diamantkomposit med en ytrengöringsmetod. Metoden skulle vara mera effektiv än den manuella sandblästring som används idag för att ytrengöra detaljen. Detaljen är liten och har ett vitalt spår som ska rengöras. Detta ställer höga krav på effektiva metoder. De metoder som tas upp teoretiskt i examensarbetet är bland annat blästring, trumling och laserrengöring. Ett urval av metoderna testades. Den metod som utmärkte sig främst I testerna var automatisksandblästring. Det gav lika bra resultat som manuell sandblästring men på en bråkdel av tiden som det tog för manuellsandblästring. Det gjordes även en investeringsberäkning i examensarbetet och den gav att trumling var den billigaste metoden. Slutsatsen är att automatisk sandblästring bör användas som metod. Metoden gav ett bättre resultat än övriga metoder och var mindre arbetskrävande än manuell sandblästring. / This goal of the thesis´ is to surface finish a diamond with an appropriate method. The method should be more effective than manual sandblasting, the current method in use. The part is small and it has a vital track that must be surface cleaned. This puts great demands on effective methods. The methods that are mentioned theoretically in the thesis are automatic sandblasting, tumbling and laser cleaning. A couple of methods were tested and evaluated. Automatic sandblasting was found to be most effective. That method gave an equal result compared to the manual sandblasting but with a fraction of the time compared to manual sandblasting. Within the thesis a capital budgeting have been done. The conclusion of the thesis was that the automatic sandblasting machine should be used.

SiGe 25% substrates were treated with aqueous solutions of ammonium sulfide with and without added acid to understand the adsorption of sulfur on the surface. X-ray photoelectron spectroscopy showed no sulfide layer was deposited from aqueous (NH4)(2)S alone and instead both Si and Ge oxides formed during immersion in the sulfur solution. The addition of hydrofluoric and hydrochloric acids dropped the pH from 10 to 8 and deposited sulfides, yet increased the oxide coverage on the surface and preferentially formed Ge oxides. The sulfur coverage grew with increasing concentrations of acid in the aqueous (NH4)(2)S. The simultaneous deposition of O and S is suspected to be the result of oxidized sulfur species in solution. Metal-insulator-semiconductor capacitor (MISCAP) devices were fabricated to test the electrical consequences of aqueous ammonium sulfide wet chemistries on SiGe. MISCAPs treated with acidic ammonium sulfide solutions contained fewer interface defects in the valence band region. The defect density (D-it) was on the order of 10(+12) cm(-2) eV(-1). The flat band voltage shift was lower after the acidic ammonium sulfide treatment, despite the presence of surface oxides. Adsorption of S and potentially O improved the stability of the surface and made it less electrically active. (C) 2017 American Vacuum Society.

With device scaling, the current optical lithography technique is reaching its technological limit to print small features. Extreme Ultra-Violet (EUV) lithography has shown promise to print extremely thin lines reliably and cost-effectively. Many challenges remain before introducing EUV to large scale manufacturing. The main challenge addressed in this study is particle removal from EUV mask surfaces (CrON1, CrON2, and fused silica) and thermal oxide (SiO₂). Effective pre-clean procedures were developed for each surface. As chemical cleaning methods fail to meet SEMATECH criteria, addition of megasonic energy to EUV mask cleaning baths is seen as a promising cleaning methodology. As the requirement to print fine lines needs to be met, all materials used in EUV mask fabrication either absorb the incident EUV wavelength light or reflect it. Therefore, the masks used in the industry will be reflective instead of the conventional transmissive masks. Also, for the same reason, no protective pellicle can be used leading to all the surfaces unprotected from particle contamination. To avoid the detrimental effect of the particle contamination, a cleaning study for nano-particle removal was performed. A dark field microscope was utilized to study the removal of gold nano-particles from surfaces. The cleaning procedures utilized H₂SO₄ and NH₄OH chemistries with and without megasonic irradiation. The cleaning variables were bath concentration, temperature, and megasonic power. The contamination variables were the gold nanoparticles charge and size, from 40nm to 100nm. For 100 nm negatively charged gold nano-particles deposited on a CrON1 surface, a 1:10 H₂SO₄:DI bath at boiling temperature (101°C) without megasonics gave high particle removal efficiency (PRE) values as did a 1:10 H₂SO₄:DI bath at 35°C with 100W megasonics. Comparison of removal of poly diallyl-dimethyl ammonium chloride (PDAC) coated and uncoated gold nano-particles deposited on a CrON1 surface using dilute H₂SO₄ baths indicated that the coated, positively charged nano-particles were more difficult to remove. PRE trends for different baths indicate surface dissolution (shown to be thermodynamically favorable) as the particle removal mechanism. However, experimental etch rates indicated minimal surface etching in a 10 minute bath. Increased surface roughness indicated possible local galvanic corrosion at particle sites. Low surface etching results meet SEMATECH requirements. During the fused silica surface cleaning study, particle charge (negative) and size (100 nm) of the contamination source and cleaning bath chemistry (NH₄OH) were kept constant. Low PREs were obtained at room temperature for all NH₄OH bath concentrations; however, high PREs were obtained at an elevated temperature (78°C) without megasonics and at room temperature in more dilute chemistries with megasonic power applied. Similar PRE trends were demonstrated for thermal SiO₂ surfaces. The experimental etch rates of the thermal SiO₂ agree with published values.

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No description available.

As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several challenges. A cleaning process should be environmentally benign, compatible with dielectric materials and copper, and provide residue removal from narrow and high aspect ratio features. In this work, sub-critical CO2 based mixtures have been developed to remove the etch residues; these mixtures satisfy the above requirements and can potentially replace the two step residue removal process currently used in the integrated circuit (IC) industry. Based on the chemical nature of the residue being removed, additives or co-solvents to CO2 have been identified that can remove the residues without damaging the dielectric layers. Using the phase behavior of these additives as a guide, the composition of the co-solvent was altered to achieve a single liquid phase at moderate pressures without compromising cleaning ability. The extent of residue removal has been analyzed primarily by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Various techniques such as attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy, angle-resolved XPS (ARXPS), and interferometry were used to probe the interaction of cleaning fluids with residues. Model films of photoresists and plasma deposited residues were used to assist in understanding the mechanism of residue removal. From these studies, it was concluded that residue removal takes place primarily by attack of the interface between the residue and the substrate; a solvent rinse then lifts these residues from the wafer. It has been shown that transport of the additives to the interface is enhanced in the presence of CO2. From positronium annihilation lifetime spectroscopy (PALS) studies on a porous dielectric film, it has been shown that these high pressure fluids do not cause significant changes to the pore sizes or the bonding structure of the film. Hence, this method can be used to remove post etch residues from low-k dielectric films.

The effect of substrate surface treatment (substrate sputter cleaning) in a cathodic arc plasma prior to unbalanced magnetron deposition of transition metal nitride coatings on the performance of the coated components has been investigated. In particular the influence of parameters such as ion species, ion energy and exposure time on the changes in substrate surface topography, microstructure and micro-chemistry were studied employing transmission electron microscopy, energy dispersive X-ray analysis, electron energy loss spectroscopy, X-ray diffraction, atomic force microscopy and optical microscopy. The consequences for both the microstructure of subsequently grown transition metal nitride coatings and their adhesion were elucidated. The relevance for practical applications was demonstrated using the example of dry high-speed milling tests, which showed that an appropriate choice of substrate surface pre-treatment parameters can double the life time of the coated tools. This was found to be due to an improved adhesion as a result of a combina-tion of reduced oxygen incorporation at the interface between coating and substrate and local epitaxial growth of the coating. The latter is promoted by certain sub-strate surface pre-treatment procedures, which provide clean surfaces with preserved crystallographic order.

This master thesis studies the behaviour of two aluminium alloys in ultrasonic cleaning at two different intensities, as well as the effect of a cleaning solution, Formula 815 GD-NF on the same surface have been studied with respect to surface roughness and material composition. Methods like Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and 3D topography using white light interferometry (VSI) was used to study the surface and material composition. It was found that both the ultrasonic cleaning, as well as the solution itself both increase surface roughness of the samples. When crossing a threshold in ultrasonic intensity micro jet cavitation dislodge precipitates, or areas weakened by precipitate to form a large pit. And the following heat from the jet causes the surface to oxidise, becoming more brittle, and be broken up by other cavitation phenomena to cause rapid acceleration of surface roughness in an area originating from the pit.

The photocathode is one of the key components of particle accelerator facilities that provides electrons for experiments in many disciplines such as biomedicine, security imaging, and condensed matter physics. The requirements for the electron emitting material, the so-called photocathode, are rather high because these materials should provide a high quantum efficiency, a low thermal emittance, a fast response, and a long operational lifetime. At present, none of the state-of-the-art photocathodes can fully meet all the desired requirements. Therefore, new materials that can be used as potential photocathodes are urgently needed for future developments in accelerator research. Semiconductor photocathodes such as cesium telluride are the preferred materials in particle accelerators. These photocathodes provide high quantum efficiencies of above 10 %, making them highly attractive. The crystal growth of cesium telluride, as a compound semiconductor photocathode, requires the deposition of cesium and tellurium on a suitable substrate with an ideal chemical ratio, which seems elaborate and difficult to handle. In contrast, III-V semiconductors, such as gallium arsenide and gallium nitride (GaN), represent another type of semiconductor photocathode. These commercially available semiconductors are already grown on a substrate and only require a thin film of cesium and optional oxygen to obtain a photocathode. An atomically clean surface is necessary to achieve a negative electron affinity surface, which is the main prerequisite for high quantum efficiency. In this work, p-GaN grown on sapphire by metal-organic chemical vapor deposition, was wet chemically cleaned, and transferred into an ultra-high vacuum chamber, where it underwent a subsequent thermal cleaning. The cleaned p-GaN samples were activated with Cs to obtain p-GaN:Cs photocathodes and their performance was monitored with respect to their quality, especially concerning their quantum efficiency and storage lifetime. The surface topography and morphology were examined ex-situ by atomic force microscopy and scanning electron microscopy in combination with energy dispersive X-ray spectroscopy. Treatments at different temperatures resulted in various quantum efficiency values and storage lifetimes. Moderate temperatures of 400–500 °C were found to be more beneficial for the p-GaN surface quality, which was reflected by achieving higher quantum efficiency values. After the thermal cleaning, the samples were activated with a thin layer of cesium at an average pressure of 1 x E-9 mbar. The surface morphology was studied with scanning electron microscopy and energy dispersive X-ray spectroscopy after the samples were thermally cleaned and activated with cesium. The results showed that the surface appeared inhomogeneous when the samples were cleaned at a high temperature above 600 °C. A thermal cleaning from the back side through the substrate represented another possibility but did not yield higher quantum efficiency values. An in-situ analysis method facilitates following and understanding the changes in the surface electronic states before, during, and after any treatment of p-GaN:Cs photocathodes. For this purpose, an X-ray photoelectron spectrometer was applied that was built into an ultra-high vacuum system to prepare and characterize photocathodes. It allowed the in-situ monitoring of the photocathode surfaces beginning immediately after their cleaning and throughout the activation and degradation processes. The realization of the adaption of an X-ray photoelectron spectroscopy chamber to the preparation chamber presented a significant constructional challenge. Thus, this work paid special attention to the technical aspects of in-situ sample transportation between these chambers without leaving the ultra-high vacuum environment. The p-GaN surface was cleaned with different solutions and studied by X-ray photoelectron spectroscopy and atomic force microscopy, revealing that cleaning with a so-called 'piranha' solution in combination with rinsing in ethanol works best for the p-GaN surface. A cleaning step that solely uses ethanol is also possible and represents a simple cleaning procedure that is manageable in all laboratories. Afterward, the cleaned p-GaN samples underwent a subsequential thermal vacuum cleaning at various temperatures to achieve an atomically clean surface. Each treatment step was followed by X-ray photoelectron spectroscopy analysis without leaving the ultra-high vacuum environment, revealing residual oxygen and carbon on the p- GaN surface. A thermal treatment under vacuum did not entirely remove these organic contaminations, although the thermal cleaning reduced their peak intensities. The remaining oxygen and carbon contaminants were assumed to be residuals derived from the metal-organic chemical vapor deposition process. After the cesium activation, a shift toward a higher binding energy was observed in the X-ray photoelectron spectroscopy spectra of the related photoemission peaks. This shift indicated that the cesium was successfully adsorbed to the p-GaN surface. Before the cesium activation, adventitious carbon at a binding energy of approximately 284 eV was found, which was also present after the cesium activation but did not shift in its binding energy. It was also shown that the presence of remaining carbon significantly influenced the photocathode’s quality. After the cesium deposition, a new carbon species at a higher binding energy (approximately 286 eV) appeared in the carbon 1s spectrum. This new species showed a higher binding energy than adventitious carbon and was identified as a cesium carbide species. This cesium carbide species grew over time, resulting in islands on the surface. The X-ray photoelectron spectroscopy data facilitated the elucidation of the critical role of thiscesium carbide species in photocathode degradation. Typically, the quantum efficiency of photocathodes decays exponentially. Conversely, an immense quantum efficiency loss was observed after the p-GaN:Cs photocathodes were studied by X-ray photoelectron spectroscopy. The origin of the quantum efficiency loss derived from X-rays as an external influence and was not caused by the sample’s transportation. Therefore, potential X-ray damages to the p-GaN:Cs photocathodes were investigated. These experiments showed that the adsorbed cesium and its adhesion to the p-GaN surface were strongly influenced by X-ray irradiation. The cesium photoemission peaks shifted toward a lower binding energy, while the relative cesium concentration did not. This shift indicated that X-ray irradiation accelerated the external aging of the p-GaN photocathodes and thus it was proposed to use lower X-ray beam power or cool the samples to prevent X-ray damage to cesiated photocathodes. This work shows that an exclusive activation with cesium is feasible and that a re-activation of the same sample is possible. Quantum efficiency values of 1–12% were achieved when the p-GaN, grown on sapphire, was activated. The capability of an X-ray photoelectron spectroscopy analysis allowed the in-situ monitoring of the photocathode surface and shed light on the surface compositions that changed during the photocathodes’ degradation process.