• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.165-166
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• 2002

Hydrogen free diamond like carbon (DLC) films were prepared on steel substrates by using a single ion beam in a configuration that allowed sputtering of a graphite target and at the same time allowed to impact the substrate at a grazing angle. The DLC films so prepared have improved properties with increased disorder and with modest hardness that is slightly higher than previously reported values. We have studied the effects of $N_2^+$ ions implantation on such films. It is found that the implantations of nitrogen ions into DLC films lead to chemical modifications that allowed N atoms to be incorporated into the carbon network to produce a nitrogenated DLC. Nano-indentation experiments indicated that the nitrogenated films have consistently higher hardnesses ranging from 30 to 45GPa, which represents a considerable increase in surface hardness, compared with non-nitrogenated precursor films. The investigations by XPS and Raman spectroscopy suggests that the $N_2^+$ implanted DLCs had undergone both chemical and structural modifications through the incorporation of N atoms and the increased ratio of $sp^3/sp^2$ type bonding. The observed high hardness was therefore attributable to these structural and chemical modifications. This result has implication for the preparation of super hard wear resistant films required for tribological functions in devices.

• Applied Science and Convergence Technology
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• 제24권6호
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• pp.203-214
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• 2015

We have been developing a new label-free nanobio imaging platform using non-linear optics such as Coherent Anti-Stokes Raman Spectroscopy (CARS) and ion beam techniques based on sputtering and scattering such as Secondary Ion Mass Spectrometry (SIMS) and Medium Energy Ion Scattering Spectroscopy (MEIS), which have been widely used for atomic and molecular level analysis of semiconductors and nanomaterials. To apply techniques developed for semiconductors and nanomaterials for biomedical applications, the convergence of nano-analysis and biology were tried. Our activities on label-free nanobio imaging during the last decade are summarized in this review about non-linear optical 3D imaging, ellipsometric interface imaging, SIMS imaging, and TOF-MEIS nano analysis for cardiovascular tissues, collagen thin films, peptides on microarray, nanoparticles, and cell adhesion studies and finally the present snapshot of nanobio imaging and the future prospect are described.

• 한국진공학회지
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• 제12권1호
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• pp.55-63
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• 2003

150 kV급 가스 클러스터 이온 가속기를 제자하여 $CO_2$와 $N_2O$ 클러스터의 크기를 비행시간 측정법을 통하여 조사하였다. Isolated cluster ion impact를 통하여 클러스터 이온이 고체 표면과 충돌시 1nm 정도 놀이와 수십 nm 폭을 가지는 hillock을 형성시키는 것을 원자간 척력 현미경으로 관찰하였다. 또한 hillock이 존재하는 ITO 표면에 $CO_2$ 클러스터 이온을 조사하면 단원자 이온의 충돌시 보이는 sharpening 현상과는 다른 다중 충돌에 의한 sputtering 효과가 관찰되었으며, 25 kV의 가속 전압에서 $CO_2$ 클러스터 이온을 $5\times10^{-14}\textrm{cm}^2$ 만큼을 ITO 표면에 조사시킨 경우에는 표면이 평탄화되었다. 또한 표면 거칠기가 0.3 nm 정도인 Si 기판 위에 $CO_2$ 클러스터 이온을 조사하면서 이온 조사량에 따른 표면 형상 및 거칠기의 변화를 조사하였다. $10^{12}\textrm{cm}^2$ 이하의 낮은 이온 조사량에서는 hillock들의 형성과 그 밀도의 증가로 표면의 거칠기가 증가하는 surface embossment 현상이 지배적으로 이루어졌으며, 형성된 hillock의 면적과 비조사된 곳의 면적이 같아지는 임계 이온 조사량부터는 hillock이 스퍼터링되고 그 원자들의 표면확산에 따른 hillock 사이의 valley들이 채워지는 스퍼터링과 표면의 평탄화가 이루어지는 구간이 관찰되었고, 그 이후 더 높은 이온 조사량부터는 깊이 방향으로의 식각이 진행되는 연차적인 충돌과정이 관찰되었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.35-35
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• 2001

agnesium Oxide (MgO) with a NaCI structure is well known to exhibit high secondary electron emission, excellent high temperature chemical stability, high thermal conductance and electrical insulating properties. For these reason MgO films have been widely used for a buffer layer of high $T_c$ superconducting and a protective layer for AC-plasma display panels to improve discharge characteristics and panel lifetime. Up to now MgO films have been synthesized by lE-beam evaporation, Molecular Beam Epitaxy (MBE) and Metalorganic Chemical Vapor Deposition (MOCVD), however there have been some limitations such as low film density and micro-cracks in films. Therefore magnetron sputtering process were emerged as predominant method to synthesis high density MgO films. In previous works, we designed and manufactured unbalanced magnetron source with high power density for the deposition of high quality MgO films. The magnetron discharges were sustained at the pressure of O.lmtorr with power density of $110W/\textrm{cm}^2$ and the maximum deposition rate was measured at $2.8\mu\textrm{m}/min$ for Cu films. In this study, the syntheses of MgO films were carried out by unbalanced magnetron sputtering with various $O_2$ partial pressure and specially target power densities, duty cycles and frequency using pulsed DC power supply. And also we investigated the plasma states with various $O_2$ partial pressure and pulsed DC conditions by Optical Emission Spectroscopy (OES). In order to confirm the relationships between plasma states and film properties such as microstructure and secondary electron emission coefficient were analyzed by X-Ray Diffraction(XRD), Transmission Electron Microscopy(TEM) and ${\gamma}-Focused$ Ion Beam (${\gamma}-FIB$).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.266-266
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• 2010

Ion beam sputtering(IBS)을 이용한 pattern 형성은 대상 물질의 제한이 적고 물리적 변수의 조절에 의해 쉽게 nano 구조의 형태와 크기를 조절할 수 있다는 점에서 관심을 받아오고 있다. 하지만 IBS를 이용한 pattern 형성이 어려운 물질들도 있어 다양한 기판에서의 nano pattern 형성에 관련된 많은 연구가 보고되고 있다. 본 연구발표에서는 유용한 반도체인 Si 표면에서의 IBS를 이용한 nano 구조 형성이 가능함과 그 과정에 대해 말하고자 한다. Ru을 100nm 두께로 증착시킨 Si(100)을 sputter 했을 때, Ru 표면에 잘 order된 nano pattern이 형성되었다. Sputter 시간이 증가하면서 pattern은 유지된 채 Ru이 깎여 나가다가 pattern의 가장 낮은 부분부터 Si기판이 드러나게 된다. 이 때 노출된 Si은 sputtering에 의해 깎여나가고 아직 Ru이 덮여있는 부분의 Si은 그대로 유지되어, Ru이 모두 sputter 되면서 보여지는 Si의 pattern은 Ru의 그것과 동일한 형태를 띄게 된다. 그 결과, Ru의 pattern이 Si으로 transfer되었음을 AFM과 SAM을 통해 확인할 수 있었다. 또한 IBS를 이용해 pattern 형성이 힘든 metallic glass에도 같은 방식으로 Ru을 쌓아 sputter 해봄으로써 pattern transfer를 확인해 볼 계획이다. 이러한 pattern transfer는 sputtering을 통한 pattern 형성이 어려웠던 다른 물질들에 그 가능성이 있음을 보여주고 있어 sputtering의 응용 폭이 넓어질 것을 기대한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2236-2238
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• 1999

This paper deals with the surface glow discharge characteristics and some physical properties of MgO thin films prepared by RF unbalanced magnetron sputtering(UBMS) in surface discharge type AC PDP. The minimum discharge voltage is obtained for the sample of substrate holder bias voltage -10V. The main factors that improves the discharge characteristics by applied bias voltage is considered to be due to the morphology changes or crystal structure of the MgO thin film by ion bombardment during deposition process Moreover, the anti-sputtering characteristics of MgO thin film by UBMS is more excellent than that of balanced magnetron sputtering(BMS) and E-beam evaporation method.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1287-1299
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• 2023

A new Monte-Carlo-based computer program (RDS-BASIC) is developed to simulate the transport of energetic ions in pure matter. This computer program is utilizing an algorithm that uses detailed numerical solutions for the classical scattering integral for evaluating the outcomes of the binary collision processes. This approach is adopted by several prominent similar simulation programs and is known to provide results with higher accuracy compared to other approaches that use approximations to shorten the simulation time. Furthermore, RDS-BASIC simulation program contains special methods to reduce the displacement energy threshold of surface atoms. This implementation is found essential for accurate simulation results for sputtering yield in the case of very low energy ions irradiation (near sputtering energy threshold) and also successfully solve the problem of simultaneously obtaining an acceptable number of atomic displacements per incident ions. Results of our simulation for several irradiation systems are presented and compared with their respective TRIM (SRIM-2013) and the state-of-the-art SDTrimSP simulation results. Our sputtering simulation results were also compared with available experimental data. The simulation execution time for these different simulation programs has also been compared.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.305-305
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• 2003

• 한국진공학회:학술대회논문집
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• 한국진공학회 2002년도 제23회 학술발표회 초록집
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• pp.121-121
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• 2002

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제37회 하계학술대회 초록집
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• pp.78-78
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• 2009