• 한국정밀공학회지
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• 제23권8호
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• pp.39-46
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• 2006

Nano-scale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate by a simple scratching process, has been applied instead of conventional silicon cantilever for scanning. A thin mask layer forms in the substrate at the diamond tip-sample junction along scanning path of the tip. The mask layer withstands against wet chemical etching in aqueous KOH solution. Diamond tip acts as a patterning tool like mask film for lithography process. Hence these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D micro structures in nanometer range. This study demonstrates the novel fabrication processes of the micro cantilever and diamond tip as a tool for TNL using micro-patterning, wet chemical etching and CVD. The developed TNL tools show outstanding machinability against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano machining tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.645-648
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• 2005

Microscopy has enabled the development of many advanced technologies, and higher level microscopic techniques are required according to the increase of research in nano-technology and bio-technology fields. Therefore, in many applications, we need to measure the dimension of micro-scale parts accurately, not just to observe their shapes. To establish the meter-traceability in microscopy, gratings have been widely used as a magnification standard. KRISS provides the certification service of magnification standards using an optical diffractometer and a metrological AFM (MAFM). They are based on different measurement principles, and so can give complementary information for each other. In this paper, we describe the configuration of each system and measurement procedures to certificate grating pitch values of magnification standards. Several measurement results are presented, and the discussion about them are also given. Using the optical diffractometer, we can calibrate a grating specimen with uncertainty of less than 50 pm. The MAFM can measure a grating specimen of down to 100 nm pitch value, and the calibrated values usually have uncertainty less than 500 pm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.327-330
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• 2000

The scanning Maxwell-stress microscopy (SMM) is a dynamic noncontact electric force microscopy that allows simultaneous access to the electrical properties of molecular system such as surface potential, surface charge, dielectric constant and conductivity along with the topography. The Scanning near-field optical / atomic force microscopy (SNOAM) is a new tool for surface imaging which was introduced as one application of the atomic force microscope (AFM). Operated with non-contact forces between the optical fiber and sample as well as equipped with the piezoscanners, the instrument reports on surface topology without damaging or modifying the surface for measuring of optical characteristic in the films. We report our recent results of its application to nanoscopic study of domain structures and electrical functionality in organic thin films by SMM. Furthermore, we have illustrated the SNOAM image in obtaining the merocyanine dye films as well as the optical image.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1705-1712
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• 2001

Mechanical component has striation with constant width and SEM can estimate fracture type and loading condition. SEM has benefit to fatigue fracture analysis but striation can be observed according to the kind of material and range of crack growth rate and can't. In this case, it needs AFM that can measure 3-dimensional surface profile with resolution of atomic size. In this study. to find fracture reason of torsion-mounted blade in nuclear plant, we estimate the relation between stress intensity factor range and root mean square roughness in 12% Cr steel by AFM and predict in-service loading condition of turbine blade. failure analysis is performed by finite element method and Goodman diagram on torsion-mounted blade.

• 한국정밀공학회지
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• 제18권10호
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• pp.61-68
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• 2001

Turbine blade in nuclear plant is subject to cyclic bending fatigue by high steam pressure. Especially, fatigue fracture is caused by low stress below yielding stress. Photograph by SEM doesn't have striation but photograph by AFM has striation on the fatigue fractured surface of 12% Cr steel used in turbine blade. Surface roughness $R_q$ has the linear relation with respect to stress intensity factor range ΔK and is increased linearly according to load amplitude $\textit{\Delta}P$. In this study loading condition applied to turbine blade is predicted by the relation between the gradient of $R_q$ to $\textit{\Delta}K$ and load amplitude $\textit{\Delta}P$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.375.2-375.2
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• 2016

그래핀(Graphene)은 원자 한 층 두께의 얇은 특성에 기인하여 우수한 투과도(~97.3%)를 나타내며, 높은 전자 이동도($200,000cm^2V^{-1}s^{-1}$)로 인하여 전기 전도도가 우수한 2차원 전자소재이다. 또한 유연하고 우수한 기계적 물성을 가지고 있어 실제로 다양한 소자에서 활용되고 있다. 그래핀을 이용하여 다양한 소자로 응용하기 위한 과정 중 하나인 포토리소그래피 공정(Photolithography process)은 원하는 패턴을 만들기 위해 제작하고자 하는 기판 위에 포토레지스트(Photoresist)를 코팅하는 과정을 거치게 된다. 하지만 이러한 과정은 소자 제작에 있어서 포토레지스트 잔여물을 남기게 된다. 그래핀 위에 남은 포토레지스트 잔여물은 그래핀의 우수한 전기적 특성을 저하시켜 소자특성에 불이익을 주게 된다. 본 연구에서는 수소 플라즈마를 이용하여 그래핀 위에 남은 중합체(Polymer) 잔여물을 제거한다. 사용한 그래핀은 화학 기상 증착법(Chemical vapor deposition)을 이용하여 성장시켰으며, PMMA(Poly(methyl methacrylate))를 이용하여 이산화규소(silicon dioxide) 기판에 전사하였다. 그래핀의 손상 없이 중합체 잔여물을 제거하기 위해 플라즈마 처리시간을 15초부터 1분까지 늘려가며 연구를 진행하였으며, 플라즈마 처리 시간에 따른 중합체 잔여물의 제거 정도와 그래핀의 보존 여부를 확인하기 위해 라만 분광법(Raman spectroscopy)과 원자간력현미경(Atomic force microscopy)을 사용하였다. 본 연구 결과를 통해 간단한 플라즈마 처리로 보다 나은 특성의 그래핀 소자를 얻게 됨으로써, 향상된 특성을 가진 그래핀 소자로 산업적 응용 가능성을 높일 수 있을 것이라 생각된다.

• 청정기술
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• 제18권4호
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• pp.355-359
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• 2012

본 연구에서는 보다 효율적인 광 전기화학적 수소제조를 위하여 광촉매로써 산화텅스텐에 티타늄을 함침하여 $Ti/WO_3$ 나노입자를 제조하였다. 제조한 $Ti/WO_3$의 물리적 특성은 X-선 회절분석법(XRD), 주사전자현미경(SEM), 발광분광계(PL), 원자간력 현미경(AFM), 정전기 현미경(EFM)을 통해 확인하였다. 메탄올/물 (1/1) 광분해 수소제조 실험 결과, 순수 아나타제 티타니아나 산화텅스텐 광촉매보다 $Ti/WO_3$ 광촉매에서 촉매활성이 향상되었으며, 0.5 g의 0.10 mol % $Ti/WO_3$ 촉매를 사용한 경우 8시간 반응 시 3.02 mL의 수소가 발생되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.108-111
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• 2000

We will illustrate the topographical structure and optical structure of the merocyanine dye LB films obtained by the scanning near-field optical/atomic force microscopy (SNOAM). SNOAM was recognized as a powerful tool to modify the surface as well as to characterize the topography of the surface at atomic resolution, especially for optical reaction materials. SNOAM images showed that the topographical and optical structures of these films were not only depended on the chemical property but also physical property. In the continuous measurement on these dyes, the appearance of near-field optical transmission images showed a certain dependence on the kinds of dyes and the mutual mixing ratios of dyes. These experimental results suggest that there is a certain kind of interaction between these two dyes.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.575-575
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• 2013

Indium Zinc Oxide (IZO)는 가시광 영역(380~780 nm)에서 높은 투과율과 적외선영역에서 높은 반사율을 보이는 투명산화막으로서 Flexible display 적용으로 주목 받는 재료이다. 특히 비 화학적 양론비(non-stoichiometric)로 성장된 박막은 N형 반도체 특성을 갖기 때문에 광전자 소자, 액정표시소자와 태양전지의 투명전극 재료로 이용되고 있으며, 향 후에도 수요는 계속 증가될 전망이다. 일반적으로 IZO 박막은 높은 열처리 온도에 의한 기판재료의 선택이 한정적인 단점이 있다. 따라서 최근에는 정밀하게 제어된 에너지를 가진 전자를 표면에 조사(E-beam irradiation)하여 박막의 물성을 개선하고 기판재료의 선택성을 넓히는 연구가 활발히 진행되고 있다 [1]. 본 연구에서는 RF Magnetron Sputtering 법을 이용하여 Glass 위에 IZO를 증착하였다. 스퍼터링타겟은 고순도 IZO 타겟을 이용하여 100 nm의 두께를 가지는 박막을 증착하였다. 증착된 IZO 박막에 E-beam Source ((주)인포비온)를 이용하여 E-beam irradiation energy 조건에 변화를 주어 박막의 물성 변화를 관찰하였다. IZO 박막의 두께를 측정하기 위해 SEM (Cross section)을 이용하였다. E-beam irradiation energy에 따른 가시광 영역(380~780 nm)에서의 광투 과도는 UV-Vis spectrometer를 사용하여 측정하였고, 전기적인 특성은 Hall measurement system 을 이용하여 측정하였다. 또한 박막의 결정성과 거칠기의 변화는 XRD (X-ray Diffraction)와 원자 간력현미경(Atomic Force Microscope; AFM)을 이용하여 측정하였다. Rf magnetron Sputtering 법을 이용하여 증착한 IZO 박막에 Post E-beam irradiation이 전기전도 및 광 투과특성과 결정성과 표면 조도를 향상시키는데 크게 기여함을 확인할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.48-52
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• 2001

In this paper presents an accurate AFM used that is free from the Z-directional distortion of a servo actuator is described. Two mathematical correction methods by the in-situ self-calibrationare employed in this AFM. One is the method by the integration, and the other is the method by inverse function of the calibration curve. The in situ self-calibration method by the integration, the derivative of the calibration curve function of the PZT actuator is calculated from the profile measurement data sets which are obtained by repeating measurements after a small Z-directional shift. Input displacement at each sampling point is approximately estimated first by using a straight calibration line. The derivative is integrated with reference to the approximate input to obtain the approximate calibration curve. Then the approximation of the input value of each sampling point is improved using the obtained calibration curve. Next the integral of the derivative is improved using the newly estimated input values. As a result of repeating these improving process, the calibration curve converges to the correct one, and the distortion of the AFM image can be corrected. In the in situ self-calibration through evaluating the inverse function of the calibration curve, the profile measurement data sets were used during the data processing technique. Principles and experimental results of the two methods are presented.