• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.33.2-33.2
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• 2011

CMP (Chemical-Mechanical Planarization) 공정이란 화학적 반응과 기계적 힘을 동시에 이용하여 표면을 평탄화하는 공정으로, 반도체 산업에서 회로의 고집적화와 다층구조를 형성하기 위해 CMP 공정이 도입되었으며 반도체 패턴의 미세화와 다층화에 따라 CMP 공정의 중요성은 더욱 강조되고 있다. CMP 공정은 압력, 속도 등의 공정조건과, 화학적 반응을 유도하는 슬러리, 기계적 힘을 위한 패드 등에 의해 복합적으로 영향을 받는다. CMP 공정에서, 폴리우레탄 패드는 많은 기공들을 포함한 그루브(groove)를 형성하고 있어 웨이퍼와 직접적으로 접촉을 하며 공정 중 유입된 슬러리가 효과적으로 연마를 할 수 있도록 도와주는 역할을 한다. 하지만, 공정이 진행 될수록 그루브는 손상이 되어 제 역할을 하지 못하게 된다. 패드 컨디셔닝이란 컨디셔너가 CMP 공정 중에 지속적으로 패드 표면을 연마하여 패드의 손상된 부분을 제거하고 새로운 표면을 노출시켜 패드의 상태를 일정하게 유지시키는 것을 말한다. 한편, 금속박막의 CMP 공정에 사용되는 슬러리는 금속박막과 산화반응을 하기 위하여 산화제를 포함하는데, 산화제는 금속 컨디셔너 표면을 산화시켜 부식을 야기한다. 컨디셔너의 표면부식은 반도체 수율에 직접적인 영향을 줄 수 있는 scratch 등을 발생시킬 뿐만 아니라, 컨디셔너의 수명도 저하시키게 되므로 이를 방지하기 위한 노력이 매우 중요하다. 본 연구에서는 컨디셔너 표면에 연마 잔여물 흡착을 억제하고, 슬러리와 컨디셔너 표면 간에 일어나는 표면부식을 방지하기 위하여 소수성 자기조립 단분자막(SAM: Self-assembled monolayer)을 증착하여 특성을 평가하였다. SAM은 2가지 전구체(FOTS, Dodecanethiol를 사용하여 Vapor SAM 방법으로 증착하였고, 접촉각 측정을 통하여 단분자막의 증착 여부를 평가하였다. 또한 표면부식 특성은 Potentiodynamic polarization와 Electrochemical Impedance Spectroscopy (EIS) 등의 전기화학 분석법을 사용하여 평가되었다. SAM 표면은 정접촉각 측정기(Phoenix 300, SEO)를 사용하여 $90^{\circ}$ 이상의 소수성 접촉각으로써 증착여부를 확인하였다. 또한, 표면에너지 감소로 인하여 슬러리 내의 연마입자 및 연마잔여물 흡착이 감소하는 것을 확인 하였다. Potentiodynamic polarization과 EIS의 결과 분석으로부터 SAM이 증착된 표면의 부식전위와 부식전류밀도가 감소하며, 임피던스 값이 증가하는 것을 확인하였다. 본 연구에서는 컨디셔너 표면에 SAM을 증착 하였고, CMP 공정 중 발생하는 오염물의 흡착을 감소시킴으로써 CMP 연마 효율을 증가하는 동시에 컨디셔너 금속표면의 부식을 방지함으로써 내구성이 증가될 수 있음을 확인 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.622-628
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• 2016

As the suction pad-supporting bike carrier attached to a car may be subject to an excessive dynamic load due to random vibrations and centrifugal forces during driving, its structural safety is of great concern. To examine this, the finite-element method with a fluid-structure interaction should be used because the pressure on the pad bottom is changed in real time according to the fluctuations of the force or the moment applied on the pad. This method, however, has high computing costs in terms of modeling efforts and software expense. Moreover, the accuracy of computation is not easily guaranteed. Therefore, a new method combining the experiment and computation is proposed in this paper: the bottom pressure and contact area of the pad under varying loads was measured in real time and the acquired data are then used in the nonlinear elastic finite-element calculations. The computational and experimental results obtained with the product under development showed that the safety margin of the pad under the axial loading is relatively sufficient, whereas with an excessive rotational loading, the pad is vulnerable to separation or a local surface damage; hence, the safety margin may not be secured. The predicted contact behavior under the variation of the magnitude and type of the loading were in good agreement with the one from the experiment. The proposed analysis method in this study could be used in the design of similar vacuum pad systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.527-528
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.455-456
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• 2011

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.199-204
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• 2021

In this study, an isogoemetric analysis (IGA) method that uses NURBS (Non-Uniform Rational B-Spline) basis functions in computer-aided design (CAD) systems is employed to account for the geometric exactness of curved electrodes constituting an electro-adhesive pad in electrostatic problems. The IGA is advantageous for obtaining precise normal vectors when computing the electro-adhesive forces on curved surfaces. By performing parametric studies using numerical examples, we demonstrate the superior performance of the curved electrodes, which is attributed to the increase in the normal component of the electro-adhesive forces. In addition, concave curved electrodes exhibit better performance than their convex counterparts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.344-349
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• 2017

Wall-climbing robots have been developed for various purposes, such as cleaning skyscraper windows, maintaining large structures, and welding vessels. Conventional wall-climbing robots use movement systems based on wheels or legs. However, wheeled robots suffer from slipping effects, while legged systems require many actuators and control systems for the complex linkage structure, which also increases the weight of the robot. To overcome these disadvantages, we propose a new wall-climbing robot that walks based on gorilla locomotion. The proposed robot consists of a DC drive motor, a vacuum pump for adsorption, and a micro controller for controlling the system. The performance of the robot was experimentally verified on vertical and horizontal flat surfaces. The robot could be used for various functions in industrial sites or disaster areas.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.55-56
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• 2006

This paper describes a new concept of the robot that can climb on the vertical plane. The engineering design problem of the main structure is presented and the experimental results regarding a new mechanism of climbing on the vertical wall are discussed. The locomotive motion of the robot is realized by using a series chain of two caterpillar wheels on which 24-suction pads are installed. White each caterpillar wheel rotates on the vertical plane surface, the vacuum pads are activated in sequence based on the sequential opening by specially designed mechanical valves. The detail design feature of the valve is also described in this paper. The overall size of the robot is around 460 mm in width and length, respectively, and 200 mm in height. Its mass is slightly over 14 kg. The main mechanical structure of the robot consists of driving motors, vacuum caterpillar system, steering part, vacuum pump and battery. The performance of the robot is verified on the vertical wall.

• Tribology and Lubricants
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• v.24 no.6
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• pp.326-331
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• 2008

The contact surfaces between mold and target should be in parallel for a proper imprinting process. However, large size of contacting area makes it difficult for both mating surfaces (mold and target planes) to be in all uniform contact with the expected precision level in terms of thickness and position. This is caused by the waviness of mold and target although it is very small relative to the area scale. The gripping force for both mold and target by the vacuum chuck is other major effect to interrupt the uniform contact, which must be avoided in imprinting mechanism. In this study, the cause of non-conformal contact mechanism between mold and target is investigated with the consideration of deformation due to the vacuum gripping for the size $470{\times}370\;mm^2$ LCD panel.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.980-991
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• 2023

To prevent accidents near the quay caused by a ship, ports are generally designed and constructed through navigation and berthing safety assessment. However, unpredictable accidents such as ship collisions with the quay or personal accidents caused by ropes still occur sometimes during the ship berthing or mooring process. Automatic mooring systems, which are equipped with an attachment mechanism composed of robotic manipulators and vacuum pads, are designed for rapid and safe mooring of ships. This paper deals with a displacement and velocity measurement system for the automatic mooring device, which is essential for the position and speed control of the vacuum pads. To design a suitable system for an automatic mooring device, we first analyze the sensor's performance and outdoor environmental characteristics. Based on the analysis results, we describe the configuration and design methods of a displacement and velocity measurement system for application in outdoor environments. Additionally, several algorithms for detecting the sensor's state and estimating a ship's velocity are developed. The proposed method is verified through some experiments for displacement and speed measurement targeted at a moving object with constant speed.

• Korean Journal of Agricultural Science
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• v.27 no.1
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• pp.13-19
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• 2000

The external morphology of male and female of Liriomyza trifolii (Burgess) was studied using the scanning electron microscopy (SEM). Three types of sensilla were identified on the funicle of antennae. The trichoid sensilla were most conspicious and distributed with a characteristic sharp structure at the apical end. Basiconic sensilla were showed distal curvature about $13{\mu}m$ long and $1.2{\mu}m$ to $1.4{\mu}m$ in diameter. Grooved sensilla were showed a finger-like projections at the peg apex. The function of these sensilla likely to be olfactory. The mouthparts were adapted for sucking food, and formed a elongate rostrum which was incorporated with labrum. The labrum was a small and flap-like shape. The slender and paired maxillary palp seemed to combine with each other lengthwise to long tube. The tarsus typically consisted of 5 segments, which might be variously modified, principally by thickening or flattening. The segment beared a pair of claws. Beneath the claws, there was a pair of pad-like pulvillia and a bristle-like median empodium. L. trifolii might secreted on the pulvillus and empodium an adhesive substance that enable them to cling to smooth surfaces. Male terminalia was complicated. The name 'aedeagus' seemed the best available general term for the copulatory organ, otherwise, female terminalia was usually relatively simple. This structure was reduced and formed a telescopic, eversible, and tubular ovipositor.