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Over the past few years, the chemical mechanical planarization (CMP) community has systematically characterized the device reliability issues associated with the introduction of copper metallization into integrated circuit fabrication. To gain further understanding of the impact of CMP processing on device performance, this paper reports in detail the interactions of simulated copper slurries and pristine segmented polyurethanes. These studies clearly show that polyurethane is fundamentally incompatible with some of the chemicals used in copper CMP, such as hydrogen peroxide. Experimental copper polishing data on both polyurethane and polyolefin-based pads are compared. The pad performance differences between the polyurethane and polyolefin-based pads are explained based on the chemistry of the base polymers used in the pad fabrication. These results are incorporated into the design and fabrication of a new class of polyolefins-based application specific pads.

Self-assembly of cerium oxide nanoparticles to nanorods is reported. Such nanorods have an aspect ratio of 6 with a diameter of approximately 40 nm. The formation of cylindrical supraaggregates and their subsequent growth by preferential assembling of ceria nanocrystallites along the longitudinal direction was proposed to be the probable mechanism of spontaneous self-assembly of nanorods. The supraaggregate formation was facilitated by influencing the local curvature of the micelle surface in the presence of nitrate ions as a precursor solution. The nanorods were characterized using high-resolution transmission electron microscopy with energy dispersive spectroscopy and selected area electron diffraction for their morphology, chemistry, and crystal structure.

Nanomaterials have attracted considerable interest with numerous technological developments in the last decade. Nanomaterials exhibit different physicochemical properties compared with their bulk counterparts because the diameters of the nanoparticles are less than the Bohr exciton radius. Cerium oxide based materials have been extensively studied for various technological applications. In the present study, the application of nanocrystalline cerium oxide for improvement of high–temperature–oxidation resistance of stainless steel has been studied. The role of coating of nanocrystalline cerium oxide towards improvement of high–temperature–oxidation resistance has been investigated and compared with that of the micrometre–sized cerium oxide particles. It was observed that nanocrystalline ceria improved high–temperature–oxidation resistance of AISI 304 stainless steel to a large extent compared with the micrometre–sized ceria coating. Nanocrystalline ceria coating decreased the isothermal parabolic rate constant of oxidation by more than two orders of magnitude compared with that of the bare alloy. The resistance to oxide scale spallation was also found to improve with the coating of cerium oxide nanoparticles. Secondary ion mass spectroscopy (SIMS) study of nanocrystalline ceria–coated and oxidized specimens revealed the presence of nanoceria at the outermost oxide surface, indicating a change in the oxide scale growth mechanism from outward cation diffusion to inward oxygen diffusion in the bare alloy at high temperature in dry air. The oxide scale morphology was studied using a scanning electron microscope (SEM) while a focused ion beam (FIB) technique was used to study the oxide–alloy interface. X–ray photoelectron spectroscopy (XPS) study of nanocrystalline ceria showed the presence of Ce 3+ and Ce 4+ oxidation states. It is proposed that the presence of the Ce 3+ oxidation state in nanocrystalline ceria improves the oxidation resistance of stainless steel, and the related mechanisms are discussed.

A unique, simple, inexpensive and one-step synthesis route of carbon nanotubes (CNT) supported palladium nanoparticles using a simplified arc-discharge in solution is reported. Palladium nanoparticles with 3 nm diameter were found to form during reduction of palladium tetra-chloro-square-planar complex. Pd-nanoparticles were simultaneously encapsulated in CNTs during the rolling of graphene sheets in the arc-discharge process. Energy Dispersive Spectroscopy suggests no functionalization of chlorine to the sidewall of CNTs. Study of High Resolution Transmission Electron microscopy supports the scroll mechanism for CNT formation.

Template-assisted electrodeposition is an important technique for synthesizing metallic nanomaterials with controlled shape and size. Arrays of nanostructured materials with specific arrangements can be prepared by this method, employing either an active or restrictive template as a cathode in an electrochemical cell. An overview of the template-assisted electrodeposition process to synthesize metallic nanostructures is presented in this article.

Palladium particles have been electrodeposited on AISI 316 stainless steel substrate from aqueous solution of palladium chloride. The kinetics of the electrodeposition process and growth mechanism of such threedimensionally grown palladium particles have been studied. It has been found that the kinetics of electrodeposition of palladium follows parabolic law, which indicates involvement of instantaneous nucleation and subsequent three-dimensional growth. It was also observed that the nucleation density of palladium electrodeposits was a function of the nature of the electrode substrate. The structure, morphology, texture, chemical state, and composition of the electrodeposited palladium particles have been characterized using SEM, TEM, XPS, EDS, EBSD, and OIM. The growth of the palladium nuclei situated at the grain interior was found to be more than that at the grain boundaries on steel substrate. The micron-size electrodeposited palladium particles consisted of a number of nanocrytallites. The surface morphology of the electrodeposited palladium particles was uneven due to the preferential growth of such nanocrystallites in certain crystallographic directions. The results of the present investigation indicate that the growth of the palladium electrodeposits was limited by the diffusivity of bulky palladium tetrachloro square-planar complex from bulk solution to near the electrode surface.

Tin oxide (SnO x ) semiconductor thin film is coated on Pyrex glass (silica) substrates using the sol–gel dip-coating technique utilizing alkoxide precursor. The thin film is extensively characterized for its surface morphology, chemistry, thickness, and nanocrystallite size using different analytical techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). The HRTEM sample preparation is done for the first time using focused ion-beam (FIB) milling technique. Under the given processing conditions, SnO x semiconductor thin film having thickness 100–150 nm and nanocrystallite size 6–8 nm is obtained. In view of the reported literature and the present experimental data, it is demonstrated that the film is suitable for sensing H 2 gas at room temperature. Sensitivity value as high as 394% is observed at room temperature for 4 vol.% H 2 , which is an explosive limit at room temperature for the space-based applications as set by NASA.

Cerium oxide has been investigated to be an effective coating material for high temperature applications for various alumina- and chromia-forming alloys. The present study investigates the use of microemulsion method to obtain monodispersed, non-agglomerated nanocrystalline ceria particles in the range of 5 nm using sodium bis(2-ethylhexyl) sulphosuccinate (AOT) as a surfactant. Furthermore, the use of non-agglomerated nanocrystalline ceria particles to develop improved high temperature oxidation resistant coatings on AISI 304-grade stainless steel was investigated. It was found that non-agglomerated nanocrystalline ceria particles were more effective in improving the oxidation resistance than the agglomerated nanocrystalline particles.

This article reports an easy chemical method of synthesizing boehmite nanofibers by a modified sol-gel process involving aluminum isopropoxide precursor. Nanorods of gamma-alumina have been successfully prepared after dehydration of the viscous sol at 600 degrees C for 4 h in air. The boehmite nanofibers and gamma-alumina nanorods were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy for surface chemistry and functional groups, scanning electron microscopy, high-resolution transmission electron microscopy with selected area electron diffraction, and energy-dispersed spectroscopy for morphology and structure identification. The length of the boehmite nanofibers was found to be more than 10 mum with a crystalline lattice structure. The mechanism of formation of the boehmite nanofibers included the preferential growth along the longitudinal axis due to interaction between the solvent molecules and the surface OH- groups of hydrogen bonds. It is also suggested that the boehmite nanofibers may have formed due to the inherent instability of the planar structure of the boehmite lattice. The diameter of the gamma-alumina nanorods was found to be less than 10 nm with a varying length in the range of 50-200 nm. Boehmite to gamma-Al2O3 transformation was attributed to the loss of water molecules by internal condensation of protons and hydroxyl ions.

The method of arc discharge in the solution is unique and inexpensive route for synthesis of the carbon nanotubes (CNTs), carbon onions, and other carbon nanostructures. Such a method can be used for in situ synthesis of CNTs decorated with nanoparticles. Herein, we report a simple and inexpensive optoelectronically automated system for arc discharge in solution synthesis of CNTs. The optoelectronic system maintains a constant gap between the two electrodes allowing a continuous synthesis of the carbon nanostructures. The system operates in a feedback loop consisting of an electrode-gap detector and an analog electronic unit, as controller. This computerized feeding system of the anode was used for in situ nanoparticles incorporated CNTs. For example, we have successfully decorated CNTs with ceria, silica, and palladium nanoparticles. Characterizations of nanostructures are performed using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy dispersive spectr...

An in situ, easy, and versatile method to decorate a polymer substrate with uniformly spaced centimeter-long arrays of 5-10 nm palladium nanoparticles is reported. The electrochemical deposition of palladium nanoarrays isdescribed as well as results from various microscopic and spectroscopic characterizations, such as transmission electron microscopy, scanning electron microscopy, optical microscopy, and electron spectroscopy for chemical analysis for their size, morphology, chemical constituent, and chemical state, respectively. The Pd nanoarrays were synthesized using a special kind of active template from an electrolyte solution of ionic strength 0.10626 mol g - 1 . The effect of curvature on the active template is discussed briefly. Understanding of the preferentially deposited Pd nanoparticles to form nanoarrays longitudinally under controlled conditions can lead to the preparation of low-cost, lightweight, reliable hydrogen sensors for safety monitoring applications.

Investigations were carried out to understand the effect of hydrogen peroxide as an oxidant and benzotriazole (BTA) as an inhibitor on the chemical mechanical planarization (CMP) of copper. Cu-CMP was studied using electrochemistry and removal rate measurements in solutions containing the oxidizer and the inhibitor. In the presence of 0.1 M glycine, the copper removal rate was high in the solution containing 5% H 2 O 2 at pH 2 because of a Cu-glycine complexation reaction. The dissolution rate of Cu increased due to the formation of the highly soluble Cu-glycine complex in the presence of hydrogen peroxide. Addition of 0.01 M BTA in the solution containing 0.1 M glycine and 5% H 2 O 2 at pH 2 exhibited a reduction in the Cu removal rate by the formation of a Cu-BTA complex on the surface of copper that inhibits the dissolution. X-ray photoelectron spectroscopy and secondary-ion mass spectroscopy investigations revealed the formation of a Cu-glycine complex, which aided the understanding of the mechanism of Cu-oxidant-inhibitor interaction during polishing.

Tantalum is used as a diffusion barrier and adhesion promoter layer between the dielectric material and copper interconnects. The present study was intended to investigate the effect of oxidizer and solution pH on chemical mechanical planarization of tantalum. High purity Ta disks were used to study the dissolution and oxidation kinetics under static and dynamic conditions using various solutions in acidic and alkaline pH regimes. The electrochemical measurements during dynamic polishing of a Ta disk were carried out using slurries containing silica and alumina particles with hydrogen peroxide at various pH levels. The affected surface layers of the statically etched Ta disk were investigated using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and secondary ion mass spectrometry (SIMS). Ta metal was observed to oxidize in aqueous solutions at pH 2, 4, and 12 in absence of HO. The oxidation process follows the parabolic kinetic law and oxidation rate was observed to be higher in an alkaline region than in an acidic region. In the presence of HO, however, Ta dissolved in the alkaline region. The dissolution was found to be greater at pH 12 mainly because of enhanced dissociation of HO in alkaline region. At pH 2, on the contrary, mass gain was observed probably due to an increase in OH content on the top of Ta oxide formed on the surface as confirmed by XPS and SIMS depth profile studies. XPS study revealed that the oxidation of tantalum takes place at a rapid rate and forms soluble oxotantalate and hydroxotantalate in solution at pH 12 in the presence of hydrogen peroxide. AFM study validates both the XPS and the SIMS results, indicating formation of a thin impervious oxide layer on Ta in a solution at pH 2 with 5% HO, and a porous layer was formed on Ta in solution with 5% HO at pH 12. Consequently, the dissolution rate in alkaline region was enhanced which was confirmed by dynamic removal rate measurements, electrochemistry, and XPS studies.