Slurry Measuring Techniques

According to the vendor, fluid introduced into the soil may create excess slurry. For example, it is anticipated that the creation of a barrier in hard soils may result in an overflow slurry measuring up to one half of the volume of the trench. Researchers state that barriers are limited by the depth and directional control of the drilling technology and limited by the ability on nonintmsive techniques to verify barrier continuity. 

In the preceeding sections, development of the measurement technique and analysis of gas-phase characteristics in a slurry bubble column have been made along with some comparison of the experimental data with other correlations from the literature. Up to this point, analysis of gas-phase characteristics has included only single or binary liquid components. Recently, a large effect on gas holdup and bubble size has been observed for multicomponent liquid mixtures that contain small concentrations of surface-active species (24). In their study, mixtures of alcohols and water at alcohol concentrations less than 0.1 percent caused a dramatic increase in gas holdup (up to a factor of 2) and a decrease in bubble size (up to a factor of 4) compared to those observed for the water system. The authors think the effect is the result of- interaction between molecules of different species, leading to an enrichment of one species in the interface. Therefore, in multicomponent liquid mixtures, it is necessary to have knowledge of the presence of surface-active species as well as the physical properties of the fluid. 

Measures ability of carbon to withstand handling and slurry transfer. This property is of limited value because measuring techniques are not reproducible. 

A promising flash method was proposed by Lappalainen etal. (1999), applying a new measurement technique. Bioluminescence is determined immediately after Vibrio fischeri is exposed to the soil slurry and again after an incubation period of less than one minute. The first value serves as reference, assuming that the bacteria are not yet affected by the toxicants in the sample. The second value, expressed relative to the first value, indicates the effect of the toxicant. This procedure provides an alternative for coloured and turbid samples. 

Numerous methods for measuring fluid viscosity exist, for example, capillary tube flow methods (Ostwald viscometer), Zahn cup method, falling sphere methods, vibrational methods, and rotational methods. Rotational viscometers measure the torque required to turn an object immersed or in contact with a fluid this torque is related to the fluid s viscosity. A well-known example of this type of system is the Couette viscometer. However, it should be noted that as some CMP slurries may be non-Newtonian fluids, the viscosity may be a function of the rotation rate (shear rate). An example of this is the dilatant behavior (increasing viscosity unda increasing shear) of precipitated slurries that have symmetrical particles [33]. Furthermore, the CMP polisher can be thought of as a large rotational plate viscometer where shear rates can exceed 10 s and possibly affect changes to the apparoit viscosity. The reader can refer to the comprehensive review of viscosity measurement techniques in the book by Viswanath et aL [34]. 

The volumetric gas side mass transfer coefficient (k a) Measurement techniques for IcqS are reviewed by Sharma et al. [67, 68,92] and by Laurent et al. [66]. With systems in which the gas phase resistance prevails, kQa is determined analogously to the determination of k a in a slurry reactor. In case the gas phase is perfectly mixed, it follows, analogous to Equation (29) ... 

Liquid-Solid Mixtures Liptak [Chem. Eng., 74(4), 151-158 (1967)] discusses a variety of techniques that can be used for the measurement of sohds-in-liquid suspensions or slurries. These include metering pumps, weigh tanks, magnetic flowmeter, ultrasonic flowmeter, gyroscope flowmeter, etc. 

Global planeness and large scale scratches are usually evaluated by HDI instruments as shown in Fig. 3(a) [8], which is a surface reflectance analyzer to measure flatness, waviness, roughness of a surface, and observe scratches (Fig. 3(h)), pits (Fig. 3(c)), particles (Fig. 3(d)) on a global surface. These surface defects can also be observed by SEM, TEM, and AFM. Shapes of slurry particles can be observed by SEM and TEM, and their movement in liquid by the fluorometry technique as shown in Chapter2. 

Magnetic resonance imaging has enabled the development of a completely novel type of viscometer. This technique is based on the capacity of MRI to accurately measure velocity profiles in opaque liquids. Its potential applications include many systems of industrial relevance, such as polymer melts and slurries. The data presented here clearly show that a wide range of fluid behaviors can be measured. 

Results from constant differential pressure filtration tests have been analyzed according to traditional filtration science techniques with some modifications to account for the cross-flow filter arrangement.11 Resistivity of the filter medium may vary over time due to the infiltration of the ultrafine catalyst particles within the media matrix. Flow resistance through the filter cake can be measured and correlated to changes in the activation procedure and to the chemical and physical properties of the catalyst particles. The clean medium permeability must be determined before the slurries are filtered. The general filtration equation or the Darcy equation for the clean medium is defined as... 

All the techniques described can and do work each has advantages and disadvantages depending on the slurry and manufacturing philosophy of the user. However, regardless of the approach to measure, mix, or replenish slurry, the most important goal is uninterrupted delivery of uniform-quality slurry to the polisher. 

Coppeta et al. [10] made slurry film measurements during using laser-induced fluorescence. By addition of a fluorescent dye to the polishing slurry film thickness was experimentally from the fluorescence intensity of the lubrication film as measured through a transparent substrate. Film thickness measurements were in good agreement with those of Levert et al. [7,8]. This technique can also be used to study slurry transport across the wafer surface, diameter variation in lubrication film thickness, and slurry mixing effects [11]. 

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