• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1049-1055
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• 2004

Chemical Mechanical Polishing (CMP) is referred to as a three body tribological system, because it includes two solids in relative motion and the CMP slurry. On the assumption that the abrasives between the pad and the wafer could be a major reason not only for the friction force but also for material removal during polishing, the friction force generated during CMP process was investigated with the change of abrasive size and concentration of CMP slurry. The threshold point of average coefficient of friction (COF) with increase in abrasives concentration during interlayer dielectric (ILD) CMP was found experimentally and verified mathematically based on contact mechanics. The predictable models, Mode I (wafer is in contact with abrasives and pad) and Mode II (wafer is in contact with abrasives only), were proposed and used to explain the threshold point. The average COF value increased in the low abrasives concentration region which might be explained by Mode I. In contrast the average COF value decreased at high abrasives concentration which might be regarded to as Mode II. The threshold point observed seemed to be due to the transition from Mode I to Mode II. The tendency of threshold point with the variation of abrasive size was studied. The increase of particle radius could cause contact status to reach transition area faster. The correlation between COF and material removal rate was also investigated from the tribological and energetic point of view. Due to the energy loss by vibration of polishing equipment, COF value is not proportional to the material removal rate in this experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• pp.1312-1315
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• 2004

Chemical Mechanical Polishing is referred to as a three body tribological system, because it includes two solids in relative motion and the slurry. On the assumption that the abrasives between the pad and the wafer could be a major reason of not only the friction force but also material removal during polishing. The friction force generated by the abrasives was inspected with the change of abrasive size and concentration in this paper. The variation of coefficient of friction with abrasive concentration and size could result from the condition of contact and load balance between wafer and abrasives carried by pad asperity. The simulation was performed in this paper and compared with the result of experiment. The material removal rate also estimated with abrasive concentration and size increasement.

• Tribology and Lubricants
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• v.33 no.5
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• pp.228-233
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• 2017

Chemical Mechanical Polishing of chemically stable sapphire substrates is dominantly affected by the mechanical processing of abrasives, in terms of the material removal rate. In this study, we investigated the effect of electrostatic force between the abrasives and substrate, on the polishing. If potassium chloride (KCl) is added to slurry, water molecules are decomposed into $H^+$ and $OH^-$ ions, and the amount of ions in the slurry changes. The zeta potential of the abrasives decreases with an increase in the amount of $H^+$ ions in the stern layer; consequently, the electrostatic force between the abrasives and substrate decreases. The change in zeta potential of abrasives in the slurry is affected by the slurry pH. In acidic zones, the amount of ions bound to the abrasives increases if the amount of $H^+$ ions is increased by adding KCl. However, in basic zones, there is no change in the corresponding amount. In acidic zones, zeta potential decreases as molar concentration of potassium increases; however, it does not change significantly in basic zones. The removal rate tends to decrease with increase in molar amount of potassium in acidic zones, where zeta potential changes significantly. However, in basic zones, the removal rate does not change with zeta potential. The tendencies of zeta potential and that of the frictional force generated during polishing show strong correlation. Through experiments, it is confirmed that the contact probability of abrasives changes according to the electrostatic force generated between the abrasives and substrate, and variation in removal rate.

• Tribology and Lubricants
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• v.34 no.6
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• pp.209-216
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• 2018

Sapphire is a substrate material that is widely used in optical and electronic devices. However, the processing of sapphire into a substrate takes a long time owing to its high hardness and chemical inertness. In order to process the sapphire ingot into a substrate, ingot growth, multiwire sawing, lapping, and polishing are required. The lap grinding process using pellets is known as one of the ways to improve the efficiency of sapphire substrate processing. The lap grinding process ensures high processing efficiency while utilizing two-body abrasion, unlike the lapping process which utilizes three-body abrasion by particles. However, the lap grinding process has a high material removal rate (MRR), while its weakness is in obtaining the required surface roughness for the final polishing process. In this study, we examine the effects of free abrasives in lap grinding on the material removal characteristics of sapphire substrate. Before conducting the lap grinding experiments, it was confirmed that the addition of free abrasives changed the friction force through the pin-on-disk wear test. The MRR and roughness reduction rate are experimentally studied to verify the effects of free abrasive concentration on deionized water. The addition of free abrasives (colloidal silica) in the lap grinding process can improve surface roughness by three-body abrasion along with two-body abrasion by diamond grits.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• pp.122-125
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• 2003

We investigated the effect of the abrasive and additive concentrations in Nano ceria slurry on the pad surface temperature under varying pressure through chemical mechanical polishing (CMP) test using blanket wafers. The pad surface temperature after CMP increased with the abrasive concentration and decreased with increase of the additive concentration in slurries for the constant down pressure. A possible mechanism is that the additive adsorbed on the film surface during polishing decreases the friction coefficient, hence the pad surface temperature gets lower with increase of the additive concentration. This difference of temperature was more remarkable for the higher concentration of abrasives. In addition, in-situ measurement of spindle motor was carried out during oxide and nitride polishing. The averaged motor current for oxide film was higher than that for nitride film, which means the higher friction coefficient.

• Journal of the Semiconductor & Display Technology
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• v.3 no.1
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• pp.15-20
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• 2004

Through shallow trench isolation (STI) chemical mechanical polishing (CMP) tests, we investigated the dependence of pad surface temperature on the abrasive and additive concentrations in ceria slurry under varying pressure using blanket film wafers. The pad surface temperature after CMP increased with the abrasive concentration and decreased with the additive concentration in slurries for the constant down pressure. A possible mechanism is that the additive adsorbed on the film surfaces during polishing decreases the friction coefficient, hence the pad surface temperature gets lower with increasing the additive concentration. This difference in temperature was more remarkable for the higher concentration of abrasives. In addition, in-situ measurement of spindle motor was carried out during oxide and nitride polishing. The averaged motor current for oxide film was higher than that for nitride film, meaning the higher friction coefficient.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.291-296
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• 2006

In this study, the sputtered BTO film was polished by CMP process with the self-developed $BaTiO_3$- and $TiO_2$-mixed abrasives slurries (MAS), respectively. The removal rate of BTO ($BaTiO_3$) thin film using the $BaTiO_3$-mixed abrasive slurry (BTO-MAS) was higher than that using the $TiO_2$-mixed abrasives slurry ($TiO_2$-MAS) in the same concentrations. The maximum removal rate of BTO thin film was 848 nm/min with an addition of $BaTiO_3$ abrasive at the concentration of 3 wt%. The sufficient within-wafer non-uniformity (WIWNU%) below 5% was obtained in each abrsive at all concentrations. The surface morphology of polished BTO thin film was investigated by atomic force microscopy (AFM).

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.62-66
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• 2006

Advanced CMP conditioner design requires investigations of key conditioner manufacturing parameters and their effects on pad surface and then wafer performance. In the present investigation, diamond shape, concentration, distribution, and other key manufacturing parameters are considered to improve CMP process stability and conditioner life. Self avoiding random distribution ($SARD^{TM}$) of diamond abrasives has been developed and both numerical simulation and experimental results show very stable and reliable polishing performance.

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.4 no.1
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• pp.13-18
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• 2017

Chemical mechanical polishing (CMP) is the dirtiest semiconductor process using a slurry containing chemicals and abrasives. CMP process consumes a huge amount of slurry, which affects environmental sustainability negatively. The semiconductor industry has attempted to evaluate and reduce the carbon dioxide equivalent (CDE) for environmental sustainability. In this study, the environmental impact of the concentration of the slurry components in CMP of thick copper films is investigated. The selected slurry components for copper CMP are citric acid, hydrogen peroxide ($H_2O_2$), abrasive, and benzotriazole (BTA). The carbon intensity of each slurry component is estimated from previously reported studies. During the experiments, the material removal rates (MRRs) are measured for various compositions of the slurry. The CDE is obtained by measuring electric energy, slurry, and ultrapure water (UPW) consumptions. We find that citric acid and BTA positively and negatively influence the CDE, respectively. Further, 2 wt.% of $H_2O_2$ and 4 wt.% of abrasive result in the lowest values of the CDE in thick copper CMP.

• Proceedings of the Korean Society of Precision Engineering Conference
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• pp.23-27
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• 1995

In sawing operation of synthetic jewelry, the performance of diamond cutter blade is very dependent on the blade variables. This investigation presents ecperimental results which show the effects of the blade variables such as types of diamond abrasives, grain size of diamond, concentration, and bond materials on the beavior of te blades. Based on the experimental results an optimum blade condition for the sawing of cubic zirconia was recommended.