This study addresses three major parts: (1) to establish the technology for the preparation of tubular ceramic membrane substrates; (2) to establish the technology for the preparation of tubular carbon/ceramic membranes; and (3) to reclaim water from chemical mechanical polishing (CMP) wastewaters by a combined treatment system of a novel simultaneous electrocoagulation/electrofiltration (EC/EF) process coupled with laboratory-prepared tubular composite membranes (TCMs) and evaluate its feasibility of water recycling and operating cost. First, in this work the green substrates of tubular porous ceramic membranes consisting of corn starch were prepared using the extrusion method, followed by curing, drying, and sintering processes. Experimental results have demonstrated that an addition of starch granules to the raw materials would increase the porosity, pore size, and permeability of the sintered matrices but accompanied by a decrease of the compressive strength. It revealed that the membrane substrates with desired pore sizes and permeability could be obtained by adding a proper amount of corn starch. The nominal pore sizes of the prepared membrane substrates were ranging from 1 to 2 £gm. The membrane substrates thus obtained are suitable for crossflow microfiltration applications. Second, the carbon/alumina TCMs and carbon fibers/carbon/alumina TCMs were obtained by the chemical vapor deposition (CVD) method resulting in a pore size distribution of 2 to 20 nm and a nominal pore size ranging from 3 to 4 nm. Besides, during the CVD process the reaction temperature was found to be the main factor for influencing the pore size of carbon fibers/carbon/alumina TCMs and the type of carbon fibers. When the reaction temperature was above or equal to 1000 ¢J, the pore size of TCMs increased due to the pyrolysis of thin carbon layers. The ¡§Tip-Growth¡¨ mechanism was found for tubular carbon fibers formation under such conditions. On the other hand, ¡§Base-Growth¡¨ (also known as ¡§Root-Growth¡¨) mechanism was found for curved and irregular carbon fibers formation when reaction temperature was under or equal to 950 ¢J. Third, for reclaiming water from CMP wastewaters, experimental results of laboratory-prepared carbon/alumina TCMs incorporated into the custom-made EC/EF treatment module used was found to be capable of treating oxide-CMP wastewater in a proper manner. Permeate thus obtained had a turbidity of below 0.5 NTU and the removal efficiencies of TS (total solids content) and Si were 80% and 93 %, respectively. Further, for understanding the applicability of fractional factorial design and Taguchi experimental design, two laboratory-prepared carbon fibers/carbon/alumina TCMs (i.e., Tube B and Tube E obtained from two different preparation conditions) incorporated into the EC/EF treatment module were chosen for evaluating the performance of CMP wastewaters treatment. Permeate obtained based on the fractional factorial design of experiments had a turbidity of below 1.0 NTU and the removal efficiencies of TOC (total organic carbon), Cu and Si were all above 80 % except for the TS (i.e., ranging from 72 to 74%). Permeate obtained based on the Taguchi experimental design had a turbidity of below 0.3 NTU and the removal efficiencies of TS, TOC, Cu and Si were ranging from 82 to 91%. Apparently, similar optimum operating conditions were obtained from the fractional factorial design and Taguchi experimental design. Permeate thus obtained could be reused as the make-up water of cooling towers. The operating cost of Cu-CMP wastewater treatment based on a total water reclaim of 600 m3 per day was determined to be NT$ 98 (i.e., US$ 3.22) and NT$ 35 (i.e., US$ 1.05) per m3 of permeate for Case 1 (i.e., the filtration area of 0.0189 m2 in one EC/EF module) and Case 2 (i.e., the filtration area of 0.0801 m2 in one EC/EF module), respectively.

This dissertation presents a series of studies related to the characterization and optimization of consumables during Chemical Mechanical Planarization (CMP). These studies are also evaluated with the purpose of reducing the cost of ownership as well as minimizing the potential environmental impacts. It is well known that pad-wafer contact and pad surface micro-structure have significant impacts on polishing performance. The first study in this dissertation investigates the effect of pad surface contact and topography on polishing performance during copper CMP. Two different types of diamond discs (3M A2810 disc and MMC TRD disc) are used to condition the polishing pad. Pad surface contact area and topography are analyzed using laser confocal microscopy and scanning electron microscopy (SEM) to illustrate how variations in pad surface micro-texture affect the copper removal rate and the coefficient of friction (COF). Polishing results show that the 3M A2810 disc generates significantly higher COF (16%) and removal rate (39%) than the MMC TRD disc. Pad surface analysis results show that the 3M A2810 disc and MMC TRD disc generate similar pad surface height probability density function and pad surface abruptness. On the other hand, the MMC TRD disc generates large flat near contact areas that correspond to fractured and collapsed pore walls while the 3M A2810 disc generates solid contact area and clear pore structures. The fractured and collapsed pore walls generated by the MMC TRD disc partly cover the adjacent pores, making the pad surface more lubricated during wafer polishing and resulting in a significantly lower COF and removal rate. In the next study, the individual "large" pad surface contact areas are differentiated from the "small" contact areas and their role in copper CMP is investigated. Surface topography and the structure of a typical individual large contact area are examined via laser confocal microscopy and SEM. In addition, the Young's Modulus of the pad surface material is simulated. A case study is presented to illustrate the role of the individual large contact area of IC1000 K-groove pad in copper CMP. SEM analysis shows that the individual large pad surface contact areas are induced by fractured pore walls and loosely attached pad debris. Simulation results indicate that individual large contact areas correspond to very low values of the Young's modulus (about 50 MPa). Such low values indicate that the pad material is soft and the summit underlying the individual large contact is not fully supported. As a result, individual large contact area implies low contact pressure and may contribute little to removal rate. Case study results confirm that the individual large contact area has minimal contribution to removal rate and indicate that the removal rate is mainly caused by small individual contact areas. In our case, small contact areas correspond to those smaller than 9 square microns. We believe that this methodology can be also applied for other kinds of pad, although the threshold values that may define "small" and "large" individual contact areas for different pads and processes need to be further investigated. In the third study, the effect of pad surface micro-texture in interlayer dielectric CMP is also investigated. Blanket 200-mm oxide wafers are polished and the polishing pad is conditioned under two different conditioning forces (26.7 and 44.5 N). Results show that when conditioning force is increased from 26.7 to 44.5 N, oxide removal rate increases by 65% while COF increases by only 7%. Pad surface contact area and topography are measured and analyzed to illustrate their effects on the oxide removal rate. While the two conditioning forces generate similar pad surface abruptness, pad surface contact area is significantly lower (by 71%) at the conditioning force of 44.5 N. Such dramatic decrease in pad surface contact area leads to a significant increase in local contact pressure and therefore results in a significant increase in oxide removal rate. The oxide removal rate and local contact pressure exhibits a Prestonian relationship. Besides the above studies on the effect of the pad surface micro-texture during blanket wafer polishing, the fourth study investigates how pad micro-texture affects dishing and erosion during shallow trench isolation (STI) patterned wafer polishing. Two different types of diamond discs (3M A2810 disc and MMC TRD disc) are used to condition the pad during wafer polishing. Dishing and erosion analysis for the patterned wafer polishing is performed using a surface profiler. To illustrate the effect of pad surface micro-texture on dishing and erosion, pad surface abruptness and mean pad summit curvature are analyzed using laser confocal microscopy. Polishing results show that the two discs generate similar blanket wafer removal rates, while the MMC TRD disc generate significantly higher dishing and erosion than the 3M A2810 disc during patterned wafer polishing. Results of pad surface micro-texture analysis show that the MMC TRD disc generates sharper asperities with higher mean pad summit curvature than the 3M A2810 disc, resulting in higher dishing and erosion. Another contribution of this dissertation is the development of a slurry film thickness quantification technique using ultraviolet-enhanced fluorescence. The technique is developed to measure slurry film thickness at any location of interest. In the next study of this dissertation, this new technique is applied to determine how two different slurry application/injection schemes (standard pad center area application method and novel slurry injection system) along with various polishing conditions such as sliding velocity, ring pressure and slurry flow rate affect slurry availability in the bow wave region of the polisher. For the standard pad center area application method, slurry is directly applied onto the pad center area and a large amount of fresh slurry flow directly off the pad surface without flowing to the pad-retaining ring interface due to the centrifugal forces. For the novel slurry injection system, slurry is introduced through an injector that is placed adjacent (<3 cm) to the retaining ring on the pad surface. Such a close distance between the injector and retaining ring allows most of the fresh slurry to be delivered efficiently to the leading edge of the retaining ring after it is injected onto the pad surface. Results show that the novel slurry injection system generates consistently thicker bow waves (up to 104 percent) at different sliding velocities, slurry flow rates and ring pressures, therefore providing more slurry availability for the pad-retaining ring interface and potentials for slurry consumption reduction in CMP processes. First order calculations yield estimates of slurry savings associated with the novel slurry injection system ranging between 8 and 48 percent depending on specific process conditions. In the last study of this dissertation, the effect of retaining ring slot design and polishing conditions on slurry flow dynamics at the bow wave is investigated. The ultraviolet-enhanced fluorescence technique is employed to measure the slurry film thickness at the bow wave for two retaining rings with different slot designs. Multiple sliding velocities, slurry flow rates and ring pressures are investigated. Results show that the retaining ring with the sharp angle slot design (PEEK-1) generates significantly thicker (on average 48%) slurry films at the bow wave than PEEK-2 which has a rounded angle slot design. For PEEK-1, film thickness at the bow wave increases with the increasing of flow rate and ring pressure and decreases with the increasing of sliding velocity. On the other hand, film thickness at bow wave does not change significantly for the PEEK-2 ring at different polishing conditions indicating an apparent robustness of the PEEK-2 design to various operating conditions. With retaining rings having different designs, and all else being the same, a thinner bow wave is preferred since it is indicative of a ring design that allows more slurry to flow into the pad-wafer interface. Therefore, the work underscores the importance of optimizing retaining ring slot design and polishing conditions for efficient slurry utilization.

Precision optics can be accurately fabricated by computer controlled optical surfacing (CCOS) that uses well characterized polishing tools driven by numerically controlled machines. The CCOS process is optimized to vary the dwell time of the tool on the workpiece according to the desired removal and the calibrated tool influence function (TIF), which is the shape of the wear function by the tool. This study investigates four major topics to improve current CCOS processes, and provides new solutions and approaches for the next generation CCOS processes.The first topic is to develop a tool for highly aspheric optics fabrication. Both the TIF stability and surface finish rely on the tool maintaining intimate contact with the workpiece. Rigid tools smooth the surface, but do not maintain intimate contacts for aspheric surfaces. Flexible tools conform to the surface, but lack smoothing. A rigid conformal (RC) lap using a visco-elastic non-Newtonian medium was developed. It conforms to the aspheric shape, yet maintains stability to provide natural smoothing.The second topic is a smoothing model for the RC lap. The smoothing naturally removes mid-to-high frequency errors while a large tool runs over the workpiece to remove low frequency errors efficiently. The CCOS process convergence rate can be significantly improved by predicting the smoothing effects. A parametric smoothing model was introduced and verified.The third topic is establishing a TIF model to represent measured TIFs. While the linear Preston's model works for most cases, non-linear removal behavior as the tool overhangs the workpiece edge introduces a difficulty in modeling. A parametric model for the edge TIFs was introduced and demonstrated. Various TIFs based on the model are provided as a library.The last topic is an enhanced process optimization technique. A non-sequential optimization technique using multiple TIFs was developed. Operating a CCOS with a small and well characterized TIF achieves excellent performance, but takes a long time. Sequential polishing runs using large and small tools can reduce this polishing time. The non-sequential approach performs multiple dwell time optimizations for the entire CCOS runs simultaneously. The actual runs will be sequential, but the optimization is comprehensive.

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<p><font face="TimesNewRomanPSMT"> <p align="left">The aim of this study was to investigate the color stability of two provisional restorative materials used in crown and bridge cases upon exposure to different tea staining solutions and to evaluate the effectiveness of a polishing technique in removing the tea stains from the stained provisional restorative materials.</p> </font></p>

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In this study, the new predictive model for the micro-grinding process was developed by consolidating mechanical and thermal effects within the single grit interaction model at microscale material removal. The size effect of micro-machining was also included in the proposed model. In order to assess thermal effects, the heat partition ratio was experimentally calibrated and compared with the prediction of the Hahn model. Then, on the basis of this predictive model, a comparison between experimental data and analytical predictions was conducted in view of the overall micro-grinding forces in the x and y directions. Although there are deviations in the predicted micro-grinding forces at low depths of cut, these differences are reduced as the depth of cut increases. On the other hand, the optimization of micro machine tools was performed on the basis of the proposed design strategy. Individual mathematical modeling of key parameters such as volumetric error, machine working space, and static, thermal, and dynamic stiffness were conducted and supplemented with experimental analysis using a hammer impact test. These computations yield the optimal size of miniaturized machine tools with the technical information of other parameters.

This project is a fundamental proof of concept to look at the feasibility of using field activated abrasive particles to achieve material removal on a substrate. There are a few different goals for this project. The first goal is to prove through visualization that particle movement can be influenced and controlled by changes in electric field. The second goal is to fundamentally prove that particles controlled by electric field can remove material from a substrate. Third, it should be shown that changes in electric field can control the amount of material being removed in a given amount of time. A mathematical model will be presented which predicts metallic material removal rates based on changes in electric field strength. In this project, a technique combining concepts from electrokinetics, electrochemical mechanical planarization, and contact mechanics is proposed, aiming at enhancing planarization performance. By introducing an AC electric field with a DC offset, we try to achieve not only a better control of metallic material removal but also more flexible manipulation of the dynamic behaviour of abrasive particles. The presence of electric field will lead to electrokinetic phenomena including electroosmotic flow of an electrolyte solution and electrophoretic motion of abrasive particles. As a result, we aim to improve both the mechanical performance of planarization that is largely determined by the polishing parameters (e.g. down pressure, rotation speed, pads, and types of abrasives) and the chemical performance of planarization that is governed by selective and collective reactions of different chemical ingrediants of the slurry with the sample surface. The aim is also to understand and improve the interactions of abrasive particles with the sample.

Thesis (M.Sc. (Hons)) -- University of Western Sydney, Nepean, 2000. / "Thesis submitted for the degree of Master of Engineering (Hons), School of Mechatronic, Computer & Electrical Engineering, University of Western Sydney, Nepean" Bibliography : leaves 129-141.