This work measured and compared the effluent from the chemical mechanical polishing (CMP) of silicon dioxide using ceria slurry and ceria fixed abrasive. CMP waste streams were tested for total solids, cerium, silicon, and 6 nm to 20 μm diameter particles. The concentration of cerium and total solids in the effluent were very different for the two polishes studied. The fixed abrasive polish produced 94% less CeO2 emissions per SiO2 removed. The higher ceria levels in the slurry effluent are associated with 99-279 nm particles, and attributed to ceria abrasive. The lower concentration of ceria in the effluent from the fixed abrasive process is due to the lower wear rate of mineral from the fixed abrasive, compared to the more environmentally mobile mineral in the slurry. These results support the "bonded" nature of the abrasive particles in fixed abrasive polishing and are relevant to sustainability strategies that seek to reduce particle emissions in surface conditioning technology.

In this study, the capacitances of stainless steel-carbon composite electrodes in 1.0M Na2SO4 were determined as a function of stainless steel loading, sintering temperature, and sintering time (i.e., O. 1-0.5g of stainless steel fiber/lg of carbon fiber, 1323-1423 K, and 2.5-152 min, respectively). Kinetic parameters were determined for stainless steel sintering and catalytic carbon gasification by weight loss measurements and capacitance changes using ac impedance, single potential step methods, and cyclic voltammetry. Apparent activation energies for carbon gasification and sintering were found to be 80 and 200 kJ/mol, respectively. Measured reaction rates and kinetic parameters were used to verify the importance of stainless steel-carbon contacts toward overall electrode capacitance and to successfully predict a maximum capacitance of 45.3 F/g on a total electrode weight basis. This capacitance value yields energy densities of ca. 90 kJ/kg of electrode and does not require pressure for good electrical contact as do electrodes prepared from carbon powders. Capacitance and kinetic measurements demonstrate the ability to control conductivity and active surface area by adjusting: stainless steel to carbon loading, sintering temperature, and sintering time.

Due to the complexity of chemical mechanical polishing ͑CMP͒ in general and metal CMP in particular, modeling of CMP processes has been pursued only minimally in the literature. A fundamental understanding of these metal CMP processes is needed to minimize manufacturing and development costs that will continue to escalate as more devices migrate to subhalf-micrometer technologies where metallization schemes are more complicated. In this work, we have used two different models to characterize the tungsten CMP process. While the chemical Preston model is used to explain the effect of process parameters on the mean polish rate, the slurry transport model is useful in explaining the within wafer uniformity for the polishing process. We successfully validated the chemical Preston model using design of experiment ͑DOE͒ data and demonstrated the importance of slurry transport and the pad to wafer gap, to the within wafer uniformity for the embossed and regular politex polishing pads. We showed that better uniformity is obtained throughout the wafer with the embossed politex than the regular politex pad due to the presence of grooves in the embossed pad, which allow for better slurry transport across the pad. We effectively characterized the process and studied the effects of changing the various tool and process parameters on process performance.As microprocessor, logic, and wireless device dimensions continue to scale down to the subhalf-micrometer size, chemical mechanical polishing ͑CMP͒ has become the enabling technology for the planarization of the dielectric, isolation, and metal layers in these devices. The advantages of using CMP for planarization are now well understood in the industry. 1 Metal CMP processes for via and contact planarization and dual Damascene processes are rapidly becoming some of the most critical processes in the manufacture of the next generation embedded and wireless devices. Tungsten ͑W͒ continues to be the metal of choice for filling contact and/or via holes for all complementary metal oxide semiconductor ͑CMOS͒ bipolar CMOS, memory, and high performance ͑HiP͒ technologies and devices. The removal of the W overburden by CMP to planarize the W in the contact and via holes is now a standard technique in the manufacturing of all these subhalf-micrometer multilevel devices.It has been shown in the literature that the metal CMP process is substantially more complicated than has been assumed. 2 In W CMP, there are many factors that affect the efficiency of the process. These factors vary from the effect of the W CMP tool itself such as the downforce and platen speed at which the CMP tool is run, to effects of the consumables such as pads and slurries that are used in processing of the wafers. Most of these factors interact with each other and it is a challenge to try to extract the individual contributions of each of these factors to process performance with factors such as the nonuniformity of the polish, and the removal rate of the W.In general, conventional experimental methods such as a de...

Removal rates of low-k SiCOH dielectric and scratch defect density of Cu barrier CMP on a soft polyurethane pad with conditioning are characterized and compared between conventional diamond tip conditioner and two types of microreplicated diamond-coated conditioners. Data collected from high volume manufacturing environment demonstrate stable and uniform SiCOH removal rates plus lower scratch density with up to 1000 wafer passes on the soft pad with the microreplicated conditioners, relative to the conventional diamond tip conditioner. Scratch defects are categorized based upon their length and severity. The formation mechanism for each type of scratches are hypothesized. Groove depth and asperity height of soft pads are analyzed in order elucidate the observed differences in removal rates and scratch density with various different pad conditioners.

A novel approach to fabrication of composite metal‐carbon electrodes has been developed. Stainless steel fibers (2 μm diam) and carbon fiber bundles (20 μm diam) were combined with cellulose (as the binding agent) into an interwoven paper preform. The composite paper preform was then sintered to a stainless foil substrate to form the electrode structure. “Optimal sintering,” experimentally determined by the percentage of initial carbon remaining in the sintered electrode, was achieved at 1423 K in H2 for 2.5 min. Gas flow of H2 was maintained at 10 cm3/min (STP) or a linear velocity of 2.6 cm/min with a total pressure of 101 kPa. These conditions were consistent with the thermodynamics and kinetics of sintering and catalyzed carbon gasification. The composite electrode structure was shown to possess the high surface area characteristic of carbon black and the structural integrity of sintered metals. The degree of intermixing of fibers in the composite paper preforms and in the sintered electrodes was clearly shown by scanning electron microscopy (SEM). Volumetric BET measurements showed a surface area of ca. 760 m2/g of carbon for the sintered composite electrode structure compared to ca. 790 m2/g for the precursor carbon fiber. It is believed these preparation techniques offer flexibility in the properties of the composite electrode (i.e., specific surface area, void volume, thermal and electrical conductivity, etc.).