• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.221-224
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• 2002

Recently, simulation of Chemical Mechanical Polis hing is becoming more important because Process parameters on the material removal rate are complicated. And pattern-depent effects are a key concern in CMP processes. In this paper, we have been studied the changes of pattern density vs. oxide thickness with Stine's simulation model. We also have estimated the effective density using optimal window size with density mask, and have made a study of the change of oxide thickness as a function of polishing time.

• Current Optics and Photonics
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• v.1 no.6
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• pp.618-625
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• 2017

In the present research, a new bending system using a segmented vacuum chuck for Stressed Mirror Polishing (SMP) is developed. SMP is a special fabrication method for thin aspheric mirrors, where simple flat or spherical fabrication is applied while a mirror blank is deflected. Since a mirror blank is usually glued to a bending fixture in the conventional SMP process, there are drawbacks such as long curing time, inconvenience of mirror replacement, risk of mirror breakage, and stress concentration near the glued area. To resolve the drawbacks, a new bending system is designed to effectively hold a mirror blank by vacuum. For the developed bending system, the optimal bending load to achieve the designated mirror deflection is found by finite element analysis and an optimization algorithm. With the measurement results of the deflected mirror surfaces with the optimal bending loads, the feasibility of the developed bending system is investigated. As a result, it is shown that the bending system is appropriate for the SMP process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.48-54
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• 2012

In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon. However, for many companies, it is hard to produce 400mm or 450mm wafers, because of excesive funds for exchange the equipments. Therefore, it is necessary to investigate 300mm wafer to obtain a better efficiency and a good property rate. Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This research investigated the surface characteristics that apply variable machining conditions and Taguchi Method was used to obtain more flexible and optimal condition. In this study, the machining conditions have head speed, oscillation speed and polishing time. By using optimum condition, it achieves a ultra precision mirror like surface.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.21-28
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• 2008

The final polishing process is based on slurry, pad, conditioner, equipment. Therefore, the concept of wafer final polishing is also necessary for repeatability of results between polished wafers. In this study, the machining conditions have a pressure, table speed, machining time and slurry ratio. This research investigated the surface characteristics that apply variable machining conditions and response surface methodology was used to obtain more flexible and optimumal condition base on Taguchi method. On the base of estimated response surface curvature from the equation and results of Taguchi method, combined design of experiment was considered to lead to optimumal condition. Finally, polished wafer was obtained mirror like surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.34-37
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• 2004

Recently advancing mobile communication tools and I.T industry, semiconductor device is requested more integrated, faster operation time and more scaled-down. Because of these reasons semiconductor device is requested multilayer interconnection. For the multilayer interconnection chemical mechanical polishing (CMP) becomes one of the most useful process in semiconductor manufacturing process. In this experiment, we focus on understand the characterize and improve the CMP technology by control of slurry flow rate. Consequently, we obtain that optimal flow rate of slurry is 170ml/min, since optimal conditions are less chemical flow and performance high with good selectivity to Ta. If we apply this results to copper CMP process. it is thought that we will be able to obtain better yield.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.389-390
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.121-128
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• 2014

Superfinishing is essential for mirror surfaces, because among mechanical components cylindrical workpieces such as spindles must maintain precision and reliability with respect to functional characteristics. However, research on standardization of polishing film application combination to obtain mirror surfaces is insufficient. Consequently, this has been a factor in rising costs of mechanical components. Therefore, in this study, experiments have been conducted to determine efficient polishing film application combination for mirror surfaces ranging from ductile materials such as SM45C, brass, aluminium 7075, and titanium to brittle materials such as $Al_20_3$, SiC, $Si_3N_4$, and $ZrO_2$. From the experimental results, efficient polishing film application combination for metallic materials and ceramic materials is confirmed.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.346-351
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• 2020

The removal characteristics of copper (Cu) from electrochemical surface by voltage-activated reaction were reviewed to assess the applicability of electrochemical-mechanical polishing (ECMP) process in three types of electrolytes, such as HNO₃, KNO₃ and NaNO₃. Electrochemical surface conditions such as active, passive, transient and trans-passive states were monitored from its current-voltage (I-V) characteristic curves obtained by linear sweep voltammetry (LSV) method. In addition, the oxidation and reduction process of the Cu surface by repetitive input of positive and negative voltages were evaluated from the I-V curve obtained using the cyclic voltammetry (CV) method. Finally, the X-ray diffraction (XRD) patterns and energy dispersive spectroscopy (EDS) analyses were used to observe the structural surface states of a Cu electrode. The electrochemical analyses proposed in this study will help to accurately control the material removal rate (MRR) from the actual ECMP process because they are a good methodology for predicting optimal electrochemical process parameters such as current density, operating voltage, and operating time before performing the ECMP process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.487-487
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• 2009

One of the critical consumables in chemical mechanical polishing (CMP) is a specialized solution or slurry, which typically contains both abrasives and chemicals acting together to planarize films. In single abrasive slurry (SAS), the solid phase consists of only one type of abrasive particle. On the other hand, mixed abrasive slurry (MAS) consists of a mixture of at least two types of abrasive particles. In this paper, we have studied the CMP characteristics of mixed abrasive slurry (MAS) retreated by adding of $CeO_2$ abrasives within 1:10 diluted silica slurry (DSS). The slurry designed for optimal performance should produce reasonable removal rates, acceptable polishing selectivity with respect to the underlying layer, low surface defects after polishing, and good slurry stability. The modified abrasives in MAS are evaluated with respect to their particle size distribution, surface morphology, and CMP performances such as removal rate and non-uniformity. As an experimental result, we obtained the comparable slurry characteristics compared with original silica slurry in the viewpoint of high removal rate and low non-uniformity.

• Corrosion Science and Technology
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• v.22 no.6
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• pp.457-465
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• 2023

Irradiation-assisted stress corrosion cracking (IASCC) is one of the main degradation mechanisms of austenitic stainless steels, which are used as reactor internal materials. Slow strain rate testing (SSRT) has been widely applied to evaluate the IASCC initiation characteristics of proton-irradiated tensile specimens. Tensile specimens require low surface roughness for micro-crack observation, and electropolishing is the most important specimen pre-treatment process used for this. In this study, optimal electropolishing conditions were examined through analyzing results of polarization experiments and surface roughness measurements after electropolishing. Corrosion cell and electropolishing equipment were fabricated for polarization tests and electropolishing experiments using SSRT specimens. The experimental parameters were electropolishing time, current density, electrolyte temperature, and stirring speed. The optimal electropolishing conditions for SSRT tensile specimens made of type 316 stainless steel were evaluated as a polishing time of 180 seconds, a current density of 0.15 A/cm², an electrolyte temperature of 60 ℃, and a stirring speed of 200 RPM.