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The synthesis of CeO2 nanoparticles for CeO2 based slurry gains continuous emphasis on improving its performance in the chemical mechanical polishing of dielectric materials. Urea was selected to dominate the growth and morphology during the calcination process. Thermogravimetry experiments were used to analyze the the decomposition behavior. Particle morphology and size were analyzed. Crystalline phase information and surface valence were used to compare the differences in surface physical and chemical properties of ceria by different synthesis process. The CeO2 nanoparticles synthesized with urea were dispersed in water as slurry. The particle sizes of CeO2 were measured by dynamic light scattering. The Zeta potential of CeO2 dispersion were measured to show dispersing performance. The CeO2 nanoparticles synthesized with urea condensation show good monodisperse properties. The material removal rate of silicon oxide and surface quality after chemical mechanical polishing were selected to evaluate the chemical mechanical polishing performance. The CeO2 nanoparticles synthesized with urea condensation not only yielded better surface quality results than the commercial slurry but also showed a 153% (pH = 4) and 100% (pH = 10) increase in the material removal rate of silicon oxide compared to commercial. [ABSTRACT FROM AUTHOR]

Endpoint detection is an important technology in chemical mechanical polishing (CMP), which is used to capture the material interface and compensate the variations of consumables and incoming wafer thickness. This paper aimed to apply optical detection in metal CMP. An in situ optical measurement system was developed for a 12-inch CMP tool. Kinematic analysis of the scanning trajectory of the laser device indicated the relative position relationship between the device and the wafer. Average optical data within the wafer described the material removal of metal CMP. Furthermore, optical data and location described the non-uniformity of the entire wafer surface. In this research, the polishing condition and the residual of the wafer edge are characterized by optical trace. Pauta Criterion is used to discriminate the inflexion point of the material interface. The results reveal that the interface capture is accurate and effective. [ABSTRACT FROM AUTHOR]

Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing (CMP) of GaN were deeply investigated in this paper. Working as an ideal homogeneous substrate material in LED industry, GaN ought to be equipped with a smooth and flat surface. Taking the strong chemical stability of GaN into account, photocatalytic oxidation technology was adopted in GaN CMP process to realize efficient removal. It was found that, because of the improved reaction rate of photocatalytic oxidation, GaN material removal rate (MRR) increases by a certain extent with catalyst concentration increasing. Cross single line analysis on the surface after polishing by Phase Shift MicroXAM-3D was carried out to prove the better removal effect with higher catalyst concentration. Ultraviolet intensity field in H 2 O 2 -SiO 2 -based polishing system was established and simulated, revealing the variation trend of ultraviolet intensity around the outlet of the slurry. It could be concluded that, owing to the higher planarization efficiency and lower energy damage, the UV lamp of 125 W is the most appropriate lamp in this system. Based on the analysis, defects removal model of this work was proposed to describe the effects of higher catalyst concentration and higher power of UV lamp. [ABSTRACT FROM AUTHOR]

GaN is so hard and so chemically inert that it is difficult to obtain a high material removal rate (MRR) in the chemical mechanical polishing (CMP) process. This paper discusses the application of photocatalytic oxidation technology in GaN planarization. Three N-type semiconductor particles (TiO 2 , SnO 2 , and Fe 2 O 3 ) are used as catalysts and added to the H 2 O 2 –SiO 2 -based slurry. By optical excitation, highly reactive photoinduced holes are produced on the surface of the particles, which can oxidize OH − and H 2 O absorbed on the surface of the catalysts; therefore, more OH* will be generated. As a result, GaN MRRs in an H 2 O 2 –SiO 2 -based polishing system combined with catalysts are improved significantly, especially when using TiO 2 , the MRR of which is 122 nm/h. The X-ray photoelectron spectroscopy (XPS) analysis shows the variation trend of chemical composition on the GaN surface after polishing, revealing the planarization process. Besides, the effect of pH on photocatalytic oxidation combined with TiO 2 is analyzed deeply. Furthermore, the physical model of GaN CMP combined with photocatalytic oxidation technology is proposed to describe the removal mechanism of GaN. [ABSTRACT FROM AUTHOR]

When the feature size of integrated circuit continues to shrink below 14 nm, ruthenium (Ru) has become one of the most promising candidates for the application of novel barrier layer. To reveal the material removal mechanism of Ru during chemical mechanical polishing (CMP), surface characteristics of Ru in KIO 4 -based slurry were investigated. The corrosion behavior of ruthenium was measured by the surface chemistry and morphology analysis. Then the mechanical properties of the passivated/corroded surface were evaluated by AES and tribocorrosion experiments. CMP experiments were carried out to make clear the effects of surface property during polishing. It was found that the Ru surface chemistry and mechanical properties vary obviously as a function of slurry pH. In neutral slurries, the Ru surface is covered with RuO 2 ·2H 2 O/RuO 3 inhomogeneous passivation films, with the highest material removal rate obtained during the CMP process. It could be concluded that the material removal mechanism largely depends on the slurry pH values. In near neutral slurries, Ru is passivated with thick and heterogeneous oxides film, which proves the easiest to be mechanically removed during polishing. The weak alkaline slurry is preferred in order to achieve desirable polishing rate as well as avoid the formation of toxic RuO 4 . [ABSTRACT FROM AUTHOR]

The material removal mechanism of copper in a periodate-based slurry during barrier layer chemical mechanical polishing (CMP) has not been intensively investigated. This paper presents a study of the copper surface film chemistry and mechanics in a periodate-based slurry. On this basis, the controlling factor of the copper CMP material removal mechanism is proposed. The results show that the chemical and electrochemical reaction products on the copper surface are complex and vary considerably as a function of the solution pH. Under acidic conditions (pH 4) the copper surface underwent strong chemical dissolution while the corrosion was mild and uniform under alkaline conditions (pH 11). The corrosion effect was the lowest in near neutral solutions because the surface was covered with non-uniform Cu(IO 3 ) 2 ·H 2 O/Cu-periodate/copper oxides films, which had better passivation effect. The surface film thickness and mechanical removal properties were studied by AES and AFM nano-scratch tests. Based on the combined surface film analysis and CMP experiment results, it can be concluded that the controlling factor during copper CMP in a periodate-based slurry is the chemical-enhanced mechanical removal of the surface films. The periodate-based slurry should be modified by the addition of corrosion inhibitors and complexing agents to achieve a good copper surface quality with moderate chemical dissolution. [ABSTRACT FROM AUTHOR]

Although there are substantial studies on chemical mechanical polishing (CMP) processes of ruthenium (Ru) as a barrier layer in periodate-based slurries, little is known about the passivation mechanism of inhibitors and the galvanic corrosion mechanism of Cu. In this study, the synergetic effect of benzotriazole (BTA) and potassium molybdate (K 2 MoO 4 ) on the polishing performance of Ru and Cu in KIO 4 -based slurry was investigated. The galvanic corrosion of Cu in a Cu–Ru coupled system was studied from a completely different perspective. X-ray photoelectron spectroscopy combined with other measurements was used to reveal the synergetic passivation mechanism of BTA and K 2 MoO 4 . The results show that the galvanic corrosion of Cu is strongly mitigated in the presence of both BTA and K 2 MoO 4 . Based on the data, it was regarded that the adsorbed MoO 4 2− not only modified the surface structure of Ru and Cu, but also supported the adsorption of BTA passivation film. Also, it was found that insoluble salts were deposited into the gaps of the passivation film, which improved the compactness of the molybdate-BTA film. The CMP tests showed that the selectivity of the material removal rate of Cu to Ru can be evidently improved in the presence of BTA and K 2 MoO 4 . The increase of oxidizer content and the reduction of polishing down force could help to further decrease the MRR selectivity between Cu and Ru. [ABSTRACT FROM AUTHOR]

Highlights: [•] Wafer bending and fluid pressure are measured during 12-inch multi-zone CMP. [•] Multi-zone carrier has zone-loading effect on wafer bending. [•] Zone pressure configuration affects wafer bending and fluid pressure. [•] Convexly-bended wafer generates the largest fluid pressure due to a suitable wedged gap. [•] Higher edge zone pressure contributes to concave bending and lower fluid pressure. [Copyright &y& Elsevier]

In the ultra large-scale integration process, as chemical mechanical polishing (CMP) is developing to higher precision, nano level planarity and sub-nano level roughness of wafer surfaces become key problems to be overcome. In this work, a theoretical model for local and total material removal was proposed based on the particle sliding trajectories and chemical-mechanical synergy, and the material removal distribution on wafer surface were analyzed. Furthermore, the chemical-mechanical mechanism was studied and synergy maps constructed. It is found that the passivation-wear and additive-synergistic effects dominate the material removal during CMP. This study establishes a correlation mechanism between the nano material removal and global uniformity of wafer surfaces, which provides theoretical and experimental framework for optimizing the slurry and the process parameters. [ABSTRACT FROM AUTHOR]

In this study, a specially designed carrier with a one-zone pneumatic loading system that uses a thick copper disk as the workpiece was developed. Comparative studies of the fluid pressure and workpiece orientation between the disk and wafer carriers during chemical mechanical polishing were conducted. The results reveal that the copper disk leans down toward the leading edge and produces a negative-dominated (approximately 70%) fluid pressure, which differs from the multi-zone carrier but agrees with other studies in which the fluid pressure is measured from the disk side. Different balancing statuses and wedged gaps are formed in these two structures. [ABSTRACT FROM AUTHOR]

Abstract: A novel in-situ wafer bending/orientation measurement system, cooperated with our previous developed fluid pressure mapping system, was developed for 12-inch chemical mechanical polishing (CMP) equipment. Wafer bending and wafer orientation are studied for copper wafer sliding against the IC1000 pad. The results reveal a micron level wafer bending, and a slight wafer pitch angle of 10−5 degree. Both the wafer pitch angle and interfacial fluid pressure increase with the speed till a critical speed and then decrease. The convergent-dominated wedged gap caused by the convexly bended, trailing edge pitched wafer gives a reasonable explanation to the positive-dominated fluid pressure. [Copyright &y& Elsevier]

Highlights: [•] An eddy current measurement system for Cu thickness in CMP was established. [•] The nano-scale sensitivity under large lift-off distance was reached by optimizing. [•] The differential method for signal processing avoids the drift of system. [Copyright &y& Elsevier]