• Tribology and Lubricants
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• v.33 no.3
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• pp.106-111
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• 2017

Sapphire is an anisotropic material with excellent physical and chemical properties and is used as a substrate material in various fields such as LED (light emitting diode), power semiconductor, superconductor, sensor, and optical devices. Sapphire is processed into the final substrate through multi-wire saw, double-side lapping, heat treatment, diamond mechanical polishing, and chemical mechanical polishing. Among these, chemical mechanical polishing is the key process that determines the final surface quality of the substrate. Recent studies have reported that the material removal characteristics during chemical mechanical polishing changes according to the crystal orientations, however, detailed analysis of this phenomenon has not reported. In this work, we carried out chemical mechanical polishing of C(0001), R($1{\bar{1}}02$), and A($11{\bar{2}}0$) substrates with different sapphire crystal planes, and analyzed the effect of crystal orientation on the material removal characteristics and their correlations. We measured the material removal rate and frictional force to determine the material removal phenomenon, and performed nano-indentation to evaluate the material characteristics before and after the reaction. Our findings show that the material removal rate and frictional force depend on the crystal orientation, and the chemical reaction between the sapphire substrate and the slurry accelerates the material removal rate during chemical mechanical polishing.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1690-1691
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• 2011

본 논문에서는 H1N1 인플루엔자 A 바이러스(influenza A H1N1 virus) 검출을 위한 산화아연 나노구조(zinc oxide nano structure) 기반의 전기화학적 면역센서를 제작하고 그 특성을 분석하였다. H1N1 인플루엔자 A 바이러스는 빠른 전파 속도 때문에 정확하고 빠른 검출이 필요하다. 먼저, 2 $mm^2$의 표면적을 갖는 패턴된 금 전극 위에 열수방식(hydrothermal method)으로 성장시킨 산화아연 나노구조가 선택적으로 형성되도록 리프트-오프(lift-off) 방법을 사용하였다. 0.01 M phosphate buffered saline(pH 7.4)에서 2 ${\mu}g$/mL 농도의 1차 항체를 정전기력에 의해 산화아연 나노구조에 고정화한 후, 10 pg/mL ~ 5ng/mL 농도의 H1N1 항원을 적용하여 포획 항체에 결합시키고 HRP(horseradish peroxidase) 효소가 결합된 검출 항체를 항원에 결합시키는 샌드위치 ELISA법을 이용하였다. HRP와 반응하는 TMB(3,3', 5,5'-tetramethylbenzidine)와 과산화수소가 포함된 acetate buffered 용액(pH 5)을 전해질로 사용하고 순환전압전류 측정법(cyclic voltammetry)으로 센서의 특성을 분석하였다. 측정된 순환전압전류그래프(cyclic voltammogram)에서 H1N1 항원 농도 10 pg/mL ~ 5 ng/mL의 응답 전류는 276.47 ${\pm}$ 21.72 nA (평균 ${\pm}$ 표준편차, n=4) ~ 478.89 ${\pm}$ 6.21 nA로 측정되었고, logarithmic하게 증가하는 응답 전류 특성을 보였다.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.36-40
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• 2012

We have developed the detection method of the resonance frequency of micro/nano mechanical resonator using optical method. The optical interferometery method enabled us to detect the displacement change of resonators within several nm scale. The micro mechanical resonator was produced by attaching a micro mechanical cantilever to a piezo ceramic. The mass of cantilever was increased by evaporating Au using electron beam evaporator and the mass variation was estimated by detecting the resonance frequency changes.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.197-204
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• 2019

An electrochemical oxygen permeating membrane (OPM) is fabricated using Zr_0.895Sc_0.095Ce_0.005Gd_0.005O_2-δ (ScCeGdZ) as the solid electrolyte and aLa_0.7Sr_0.3MnO₃-bScCeGdZ composite (LZab, electrode) as the electrode. The crystal phase of the electrode and the microstructure of the membrane is investigated with X-ray diffraction and scanning electron microscopy. The electrochemical resistance of the membrane is examined using 2-p ac impedance spectroscopy, and LZ55 shows the lowest electrode resistance among LZ82, LZ55 and LZ37. The oxygen permeation is studied with an oxygen permeation cell with a zirconia oxygen sensor. The oxygen flux of the OPM with LZ55 is nearly consistent with the theoretical value calculated from Faraday's Law below a critical current. However, it becomes saturated above the critical current due to the limit of the oxygen ionic conduction of the OPM. The OPM with LZ55 has a very high oxygen permeation flux of ~ 3.5 × 10^-6 mol/㎠s in I = 1.4 A/㎠.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.8-13
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• 2014

As packing density in integrated circuits increases, multilevel metallization process has been widely used. But hillock formed in the bottom layers of aluminum are well known to make interlayer short in multilevel metallization. In this study, the effects of ion implantation to the metal film and deposition temperature on the hillock formation were investigated. The Al-1%Si thin film of $1{\mu}m$ thickness was DC sputtered with substrate ($SiO_2/Si$) temperature of $20^{\circ}C$, $200^{\circ}C$, and $400^{\circ}C$, respectively. Ar ions ($1{\times}10^{15}cm^{-2}$: 150 keV) and B ions ($1{\times}10^{15}cm^{-2}$, 30 keV, 150 keV) were implanted to the Al-Si thin film. The deposited films were evaluated by SEM, surface profiler and resistance measuring system. As a results, Ar implanting to Al-Si film is very effective to reduce hillock size in the metal deposition temperature below than $200^{\circ}C$, and B implanting to an Al-Si film is effective to reduce hillock density in the high temperature deposition conditions around $400^{\circ}C$. Line width less than $3{\mu}m$ was free of hillock after alloying.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.480-480
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• 2011

양극산화(anodization)는 금속을 전기화학적으로 산화시켜 금속산화물로 만드는 기술로서 최근 다양한 크기의 나노 구조를 제조하는 기술로 각광받고 있으며, 이러한 기술에 의하여 얻어지는 anodic aluminum oxide(AAO)는 magnetic data storage, optoelectronic device, sensor에 적용될 수 있는 nano device 뿐만 아니라 nanostructure를 제조하기 위한 template 및 mask로써 최근 광범위 하게 연구되고 있다. 또한, AAO는 Al2O3의 단단한 구조를 가진 무기재료이므로 solid mask로써 다른 porous materials 보다 뛰어난 특성을 갖고 있다. 또한 electron-beam lithography 및 block co-polymer 에 의한 patterning 과 비교하여 매우 경제적이며, 재현성이 우수할 뿐만 아니라 대면적에서 나노 구조의 크기 및 형상제어가 비교적 쉽기 때문에 널리 사용되고 있다. 그러나, AAO 형성 시 생기게 되는 반구형 모양의 barrier layer는 물질(substance)과 기판과의 direct physical and electrical contact을 방해하기 때문에 해결해야 할 가장 큰 문제점 중 하나로 알려져 있다. 따라서 본 연구에서는 실리콘 기판위의 형성된 AAO의 barrier layer를 Cl/BCl3 gas mixture에서 Neutral Beam Etching (NBE)과 Ion Beam Etching (IBE) 로 각각 식각한 후 그 결과와 비교하였다. NBE와 IBE 모두 Cl2/BCl3 gas mixture에서 BCl3 gas의 첨가량이 60% 일 경우 etch rate이 가장 높게 나타났고, optical emission spectroscopy (OES)로 Cl2/BCl3 플라즈마 내의 Cl radical density와 X-ray photoelectron spectroscopy (XPS)로 AAO 표면 위를 관찰한 결과 휘발성 BOxCly의 형성이 AAO 식각에 크게 관여함을 확인 할 수 있었다. 또한, NBE와 IBE 실험한 다양한 Cl2/BCl3 gas mixture ratio 에서 AAO가 식각이 되지만, 이온빔의 경우 나노사이즈의 AAO pore의 charging에 의해 pore 아래쪽의 위치한 barrier layer를 어떤 식각조건에서도 제거하지 못하였다. 하지만, NBE에서는 BCl3-rich Cl2/BCl3 gas mixture인 식각조건에서 AAO pore에 휘발성 BOxCly를 형성하면서 barrier layer를 제거할 수 있었다.

• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.345-351
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• 2004

Highly ordered pure-silica MCM-41 materials possessing well-defined morphology have been successfully prepared with surfactant used as a template. The fabrication of mesoporous silica has received considerable attention due to the need to develop more efficient materials' for catalysis, separations, and chemical sensing. The surface modified MCM-41 was used as anadsorbent for biomolecules. Silica-supported organic groups and DNA adsorption on surface modified MCM-41 were investigated by FT-IR and UV-Vis spectrometer, respectively. The use of MCM-41 as the modification of electrode surfaces were investigated electrochemical properties of metal mediators with biomolecules. The modified ITO electrodes increased peak currents for a redox process of $[Ru(bpy)_3]^{2+}$ relative to the bare electrode. The electrochemical detection of DNA by cyclic voltammetry when the current is saturated in the presence of the mediator appeared more sensitive due to a higher catalytic current on the MCM-41 supported electrodes modified by carboxylic acid functional groups. The carboxyl or amine groups on the surface of MCM-41 interact and react with the $-NH_2$ groups of guanine and backbone, respectively. Highly ordered mesoporous materials with organic groups could find applications as DNA sensors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4C
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• pp.329-337
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• 2012

Capsule Endoscope(CE) is a capsule-shaped electronic device which can examine the lesions in digestive tract of human body. Recently the medical procedure using capsule endoscope is receiving great attention to both doctors and patients, since the conventional push-typed endoscope using cables brings great pain and fear to the patients. The technique was firstly available in 2000 and is based on a convergence techniques among BT(Bio Technology), IT(Information Technology), and NT(Nano Technology). The device consists of an optical parts including LEDs(Light Emitting Diodes), an image sensor, a communication module and a power module. Capsule endoscope is the embodiment of the state-of-the art technology and requires key technologies in the various engineering fields. Therefore, in this paper, we introduce the composition of the capsule endoscope system, and compare the communication method between RF(Radio Frequency) communication and HBC(Human Body Communication), which are typically used for data transmission in the capsule endoscope. Furthermore, we analyze the specification of commercialized capsule endoscopes and present the future developments and technical challenges.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.243-248
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• 2017

Pd-doped $SnO_2$ thick film with a pure tetragonal phase was prepared on patterned Pt electrodes by an ink dropping method. Nanostructured $SnO_2$ powder with a diameter of 10 nm was obtained by a modified hydrazine method. Then the ink solution was fabricated by mixing water, glycerol, bicine and the Pd-doped $SnO_2$ powder. When the Pd doping concentration was increased, the grain size of the Pd-doped $SnO_2$ thick film became smaller. However, an agglomerated and extruded surface morphology was observed for the films with Pd addition over 4 wt%. The orthorhombic phase disappeared even at a low Pd doping concentration and a PdO peak was obtained for a high Pd doping concentration. The crack-free Pd-doped $SnO_2$ thick films were able to successfully fill the $30{\mu}m$ gap of the patterned Pt electrodes by the optimized ink dropping method. The prepared 3 wt% Pd-doped $SnO_2$ thick films showed monoxide gas responses ($R_{air}/R_{CO}$) of 4.0 and 35.6 for 100 and 5000 ppm, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.581-586
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• 2008

The MEMS solid propellant thrusters have very low thrust level for applying to the propulsion system of micro/nano satellites or the side jet thruster of smart bombs. In this research, the fabrication possibility of planar type MEMS solid propellant thrusters that have enlarged burning surface area was examined and the safety of the structure of thruster during the firing test was confirmed. The performance of a micro igniter which is the key component of the MEMS solid propellant thruster was estimated by the ANSYS Icepak and evaluated by the experiment. Finally, the thrust was measured by the micro force sensor. The levels of thrust were 300, 600 mN in the case of K=15, 20.