Search

Along with the remarkable growth in the complexity of semiconductor fabrication technology, chemical mechanical planarization (CMP) has evolved and become progressively more sophisticated over the years, enabling the implementation of novel integration schemes. This paper discusses current research and development trends in one specific aspect of the CMP technology, namely, ceria particle usage for advanced technology nodes and provides some perspectives on how to improve CMP performance metrics of the current ceria abrasives and ceria-based CMP slurries and move forward to the next phase.

Detached-Eddy Simulations of flows in weapon bays with a generic store at different positions in the cavity and with flexible fins are presented in this paper. Simulations were carried out to better understand the fluid–structure interactions of the unsteady, turbulent flow and the store. Mach and Reynolds numbers (based on the missile diameter) were 0.85 and 326.000 respectively. Spectral analysis showed few differences in the frequency content in the cavity between the store with rigid and flexible fins. However, a large effect of the store position was seen. When the store was placed inside the cavity, the noise reduction reached 7 dB close to the cavity ceiling. The closer the store to the carriage position, the more coherent and quieter was the cavity. To perform a more realistic simulation, a gap of 0.3% of the store diameter was introduced between the fin root and the body of the store. Store loads showed little differences between the rigid and flexible fins when the store was inside and outside the cavity. With the store at the shear layer, the flexible fins were seen to have a reduction in loads with large fluctuations in position about a mean. Fin-tip displacements of the store inside the cavity were of the range of 0.2% of the store diameter, and in the range of 1–2% of store diameter when at the shear layer.

SAR (Synthetic Aperture Radar) images in the northwest Bay of Bengal indicate the existence of internal waves and their occurrence and intensity is topography dependent as indicated by in-situ data and satellite information. To complement and comprehend the observations, a three-dimensional Princeton Ocean Model is applied to study the generation and propagation of internal waves. The model domain is configured with a variable curvilinear grid and the input fields comprise bathymetry, initial temperature and salinity, wind stress, air-sea heat flux and tidal information. The numerical investigation indicated a predominant activity of internal waves in the north, and the rationale is three-fold. The first one could be the stable stratification due to fresh water discharge from head-bay major river system, secondly, the significant magnitude/range of the tides and finally, the bathymetry in the coastal waters off Paradip is about 12% shallower compared to that of Visakhapatnam and further south. The cumulative effect of these causes the predominance of internal waves in the north. The core of the energy is essentially in the low-frequency range and the model is able to simulate semi-diurnal and diurnal components reasonably well up to 6 h frequency (0.162 cph).

This paper demonstrates the Scale-Adaptive Simulation approach for the computation of flows around transonic weapon bays idealised as rectangular cavities. Results are also compared with Detached-Eddy Simulations for the M219 cavity with and without doors. The Mach and Reynolds numbers (based on the cavity length) are 0.85 and 6.5\(\times 10^6\) respectively, with a grid size of 5.0 million for the cavity with doors-off and 5.5 million for the cavity with doors-on. Instantaneous Numerical schlieren contours made it possible to visualise the propagation of pressure waves in and around the cavities and also showed the high level of unsteadiness and breakdown of the shear layer for both doors on and doors off cases. Both cavities were seen to have similar acoustic signatures reaching maximum sound pressure levels of 170 dB. Spectral analyses revealed that the addition of the doors caused the second Rossiter mode to dominate along the length of the cavity. Scale-Adaptive Simulation results showed good agreement with experimental data for the M219 cavity at a tenth of the time required for Detached-Eddy Simulations.

Hydroxyl radical generation has been observed during Cu CMP using hydrogen peroxide-glycine based slurries. While the Cu dissolution/polish rates increased with increasing glycine concentration, the copper dissolution rate decreased with increasing peroxide concentration indicating the occurrence of both dissolution and passive film formation during CMP. This is further confirmed by both in situ and ex situ electrochemical experiments.

Nanometer size silicon nitride particles are synthesized using a pulsed radio frequency plasma technique. The plasma is modulated with a square-wave on/off cycle of varying period to control size and morphology and to deduce the growth kinetics. In situ laser light scattering and ex situ particle analysis are used to study the nucleation and growth. For SiH{sub 4}/Ar plasmas which nucleate silicon particles, an initial extremely rapid growth phase is followed by a slower growth rate, approaching the rate of thin film deposition on adjacent flat surfaces. In SiH{sub 4}/NH{sub 3} plasmas, silicon nitride particle size can be tightly controlled by adjusting the plasma-on time. The size dispersion of the particles is large and is consistent with a process of continual nucleation during the plasma-on period. The observed polydispersity differs dramatically from that reported from other laboratories.

not Available.

not Available.

Diamond-like carbon films have been deposited in an RF plasma discharge from binary and ternary mixtures of butadiene, argon and hydrogen. These films have been etched in oxygen plasmas. The effect of the addition of argon and/or hydrogen to the precursor gas on the deposition and etch characteristics of the film has been determined. Optical emission from the plasma during deposition has been monitored and the changes in the emission intensity of the CH 431.2 nm line have been used to make several observations on the deposition mechanism.

The rates of collisional deactivation of CO 2 (00 o 1) by formic acid, acetic acid, ethylene oxide and acetaldehyde were measured using the laser-induced fluorescence technique. We found that K CO 2 -HCOOH = 140 ± 22 ms −1 Torr −1 at 400 K, K CO 2 -CH 3 COOH varied from 156± 33 to 45.8 ± 26.7 ms −1 Ton −1 as the temperature was changed from 500 to 750 K, K CO 2 -C 2 H 4 O varied from 101 ± 33 to 55.5 ± 7.3 and K CO 2 -CH 3 CHO from 48.6 ± 10.7 to 26.5 ± 4.9 ms −1 Torr − in the temperature range 300–650 K.

The possibility of using infrared Q-switched gas lasers to determine the composition of a gas mixture both when it is fixed and when it is varying with time as in a chemical reaction is discussed.

We extend our earlier calculations based on the weak bias model to the dissociation of H 2 , O 2 , N 2 , Cl 2 , and F 2 in the limit of infinite dilution with Ar incorporating some improvements. The results show that the weak bias model provides a quantitative description for all molecules considered. Within this framework the importance of anharmonicity on the disociation process is discussed.

The deactivation of CO 2 (00 0 1) by ethane in the temperature range 300–600 K has been studied using a laser induced fluorescence technique. The energy transfer cross section decreased from 0.23 A 2 at 300 K to 0.16 A 2 at 600 K. The magnitude of the cross section is consistent with the expectation that near resonant V-V energy transfer processes are responsible for the energy transfer between CO 2 (00 0 1) and ethane during collisions even though the observed temperature dependence of the energy transfer cross section does not follow that predicted by the existing theories.

Mohan, R., Prahlada Rao, D. and Babu, S.V., 1986. Equation of state calculations for CO 2 , C 2 H 4 and N 2 using perturbation theory. Effect of damping the quadrupole—quadrupole and induced-quadrupole series at small intermolecular separations. Fluid Phase Equilibria , 25: 171-193. Pure component equation of state (EOS) and thermodynamic property calculations are made for three quadrupolar molecues CO 2 , C 2 H 4 and N 2 . A simple ‘spherical + quadrupole—quadrupole (Q—Q) + induced-quadrupole (ind-Q)' potential model is assumed to represent the molecular interaction. However, the usual Q—Q and ind-Q interaction energy series expansion expressions are retained only beyond a chosen intermolecular separation, r cut-off , close to the molecular size. For smaller separations, the diverging nature of the series is damped in an extreme manner by putting these interaction energies to zero. Perturbation theory and an optimisation procedure are used to calculate the reduced thermodynamic quantities, the optimal values of the parameters, σ, e, and finally the saturation loci, pressure, entropy, internal energy at high densities for the real systems. A comparison with experimental data indicates the usefulness of considering damped multipole—multipole, induced-multipole interactions in high pressure studies.

A model that takes into account mass transfer resistances at the polymer-melt and at the melt-carrier gas interfaces during the course of thermal degradation of relatively ‘large’ samples of polymer, is proposed. It is tested against experimental weight loss data for polypropylene, in the temperature range 390–430°C, obtained from the pyrolysis of 0·1–5 g samples. The weight loss data do not follow first-order kinetics and depend on the sample size. It is found that the model is capable of predicting the experimental observations.

Chakravarty, T., Sivasubramanian, M.S. and Babu, S.V., 1985. Representation and calculation of three liquid—phase equilibria of two ternary systems. Fluid Phase Equilibria , 19:221-231. Liquid-phase compositions for the two ternary systems, aniline—heptane—water (A—H—W) and glycol—lauryl alcohol—nitromethane (G—LA—NM), were calculated using the UNIQUAC equation and the van Laar equation developed by Chien and Null (1972), at two different temperatures using only binary data. The phase-splitting algorithm of Gautam and Seider (1979a,b) was used to minimize the free energy. Both models predict phase compositions that agree very well with each other and with the available experimental data (except for the lauryl alcohol-rich phase in the G—LA—NM system at 22 °C).

A correlation for the supersaturation to nucleation as a function of reduced temperature is presented. For fifteen different fluids. In S is a linear function of ( T r −1 - 1) 3/2 as predicted by theory. The slopes of the temperature correlation are further correlated with the Eotvos constant of each fluid to the 3/2 power.

Combining the advantages of low temperature (below 50°C) solar energy collection and high temperature thermal energy conversion into electrical power, a scheme for continuous power generation is proposed. This scheme is based on the concept of “concentration difference energy system” proposed by Isshiki. Make-up steam generated at about 6 kPa by flashing water at 45°C and exhaust steam from a turbine are fed to a cascade of absorber-boiler units to produce steam at a turbine inlet pressure of 2.4 MPa. The absorber-boiler cascade operates along the saturation line of CaCl 2 solution taking advantage of b.p. elevation of aqueous CaCl 2 solution. Large inexpensive solar farms are used to obtain hot water and to concentrate effluent dilute CaCl 2 solution taking advantage of the low humidity conditions prevalent in arid zones. Based on a detailed study of the performance of various components of the scheme, its economic feasibility is evaluated. Preliminary cost estimates show that power production cost is about 0.25 $/kWh and 0.04 $/kWh for plant capacities of 1 and 100 MW, respectively.

Homogeneous nucleation kinetics are rederived in a manner fundamentally similar to the approach of classical nucleation theory with the following modifications and improvements. First, the cluster is a parent phase cluster and does not require energization to the parent state. Second, the thermodynamic potential used to describe phase stability is a continuous function along the pathway of phase decomposition. Third, the kinetics of clustering corresponds directly to the diffusional flux of monomers through the cluster distribution and are formally similar to classical theory with the resulting kinetic equation modified by two terms in the preexponential factor. These terms correct for the influence of a supersaturation dependent clustering within the parent phase and for the influence of an asymmetrical cluster concentration as a function of cluster size at the critical cluster size. Fourth, the supersaturation dependence of the nucleation rate is of the same form as that given by classical nucleation theory. This supersaturation dependence must however be interpreted in terms of a size dependent surface tension. Finally, there are two scaling laws which describe supersaturation to either constant nucleation rate or to the thermodynamically determined physical spinodal.

It is shown that resonant energy exchange between two gases can alter the absorption of radiation by either, and that hydrocarbons present up to 100 ppm in the atmosphere as pollutants affect its absorption at 10.6 μ. This reduces the initial cooling time reported in the transmission of 10.6 μ laser beams in the atmosphere.