• 센서학회지
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• 제5권5호
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• pp.69-77
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• 1996

Pt/Cr 이중층과 E-beam으로 증착된 산화막으로 구성된 발열체의 발열특성과 열처리 온도에 따른 Pt/Cr 이중층의 전기적, 구조적 특성을 살펴보았다. E-beam으로 증착된 산화막을 갖는 발열체의 표면 방사율(${\varepsilon}$)은 0.5임을 열전대와 I.R. Thermo-Vision System을 통하여 확인할 수 있었다. 한편 열처리전 Pt/Cr의 면저항은 Cr의 두께와는 무관한데, 이는 백금과 크롬의 계면에 형성된 산화크롬에 의한 것으로 사료되며, 열처리 온도가 증가함에 따라 Cr의 외부확산이 증대되고, Pt(220)면의 결정립이 성장함을 AES 분석결과와 SEM 촬영, XRD 분석을 통하여 알 수 있었다. 열처리 온도에 따른 특성 분석결과, $500^{\circ}C$에서 열처리한 Pt/Cr 이중층이 안정된 결정구조를 갖음을 XRD, AES 분석결과로 확인할 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.53-56
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• 2004

The a-Si:H TFT using ferroelectric of SrTi $O_3$as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$and S $i_3$ $N_4$. Ferroelctric increases on-current, decreases thresh old voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, refractive index of 1.8~2.0 and resistivity of 10$^{13}$ - 10$^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60~100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8~20${\mu}{\textrm}{m}$ and channel width of 80~200${\mu}{\textrm}{m}$. And it shows that drain current is 3.4$mutextrm{A}$ at 20 gate voltage, $I_{on}$ / $I_{off}$ is a ratio of 10$^{5}$ - 10$^{8}$ and $V_{th}$ is 4~5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $mutextrm{A}$ at 20 gate voltage and $V_{th}$ is 5~6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.zed.d.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.166-166
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• 2007

ZnO는 육방정계(wurtzite) 결정구조를 지니며 상온에서 3.37eV의 wide band gap을 갖는다. ZnO의 엑시톤 결합 에너지는 GaN에 비해 2.5배 높은 60meV로서 고효율의 광소자 적용 가능성이 높다. 또한 고품위의 박막합성이 가능하다. 이러한 특성 때문에 display소자의 투명전극, 광전소자, 바리스터, 압전소자, 가스센서 등에 폭 넓게 응용되고 있다. ZnO박막의 제조는 스퍼터링, CVD, 진공증착법, 열분해법 등이 있다. 본 논문에서는 RF 마그네트론 스퍼터에 의해 제작된 ZnO 박막에 CMP공정을 수행하여 연마율과 비균일도 특성 및 광투과 특성을 연구하였다. ZnO박막은 $2{\times}2Cm$의 Corning glass위에 증착되었다. 로터리 펌프와 유확산 펌프를 이용하여 초기진공을 $2{\times}10^{-6}$ Torr까지 도달시킨 후 Ar과 $O_2$를 주입하였다. 증착은 상온에서 이루어졌으며 공정압력은 $6{\times}10^{-2}$Torr이였다. 초기의 불안정한 상태의 풀라즈마를 안정시키기 위해 셔터를 이용하여 pre-sputtering을 하였다. CMP 공정조건은 플레이튼 속도, 슬러리 유속, 압력은 칵각 60rpm, 90ml/min, $300g/cm^2$으로 일정하게 유지하였으며 헤드속도는 20rpm에서 100rpm까지 증가시키면서 연마특성을 조사하였다. 실리카슬러리의 적합성을 알아보기 위해 DIW와 병행하여 CMP공정을 수행하고 비교 분석하였다. CMP공정 결과 광투과도는 굉탄화된 표면의 확보로 인해 향상된 특성을 보였다. 실리카 슬러리를 사용하여 CMP를 할 경우는 헤드속도는 저속으로 하여야 양호한 연마특성을 얻을 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.84-87
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• 2005

본 논문에서는 p-type 고분자 물질인 P3HT (Poly-3-hexylthiophene)를 잉크젯 프린팅 방식으로 활성화층을 적층함으로써 Organic thin film transistor를 제작하여 이에 대한 특성을 연구하였다. Piezoelectric 방식의 잉크젯 프린팅을 이용하여 P3HT single drop jetting 시 두께 $150{\sim}200{\AA}$, 직경 약 70 ~ 80 um정도의 drop profile을 얻을 수 있었다. P3HT의 solvent로서 Chlorobenzene을 사용하여 농도 약 0.5 wt.%의 Ink-jet용 ink를 제작하여 이를 Channel Width 37, 236 um 크기의 Au 전극 위에 jetting 하여 각각의 특성을 측정하였다. 상기 실험은 상온의 외부환경에서 실시되었으며 실험 결과 최대 ${\mu}=1{\times}10^{-2}\;cm^2/Vsec$, $I_{on}/I_{off}=10^3{\sim}10^4$ 정도로서 off current가 높은 편이나 이동도 측면에서는 다른 방법의 박막 증착 실험결과와 비교할 때 동등 수준의 결과를 얻을 수 있었다.

• 대한기계학회논문집B
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• 제30권5호
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• pp.413-421
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• 2006

The bubble dynamics induced by direct laser heating is experimentally analyzed as a first step to assess the technical feasibility of laser-based ink-jet technology. To understand the interaction between laser light and ink, the absorption spectrum is measured for various ink colors and concentrations. The hydrodynamics of laser-generated bubbles is examined by the laser-flash photography. When an Ar ion laser pulse (wavelength 488 nm) with an output power up to 600 mW is incident on the ink solution through a transparent window, a hemispherical bubble with a diameter up to ${\sim}100{\mu}m$ can be formed with a lifetime in a few tens of microsecond depending on the laser power and the focal-spot size. Parametric study has been performed to reveal the effect of laser pulse width, output power, ink concentration, and color on the bubble dynamics. The results show that the bubble generated by a laser pulse is largely similar to that produced by a thin-film heater. Consequently, the present work demonstrates the feasibility of developing a laser-actuated droplet generation mechanism for applications in ink-jet print heads. Furthermore, the results of this work indicate that the droplet generation frequency is likely to be further increased by optimizing the process parameters.

• 대한금속재료학회지
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• 제48권10호
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• pp.951-956
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• 2010

This study examined the effect of copper and sulfuric acid concentrations on the surface morphology and physical properties of copper plated on a polyimide (PI) film. Electrochemical experiments with SEM and a four-point probe were performed to characterize the morphology and mechanical characteristics of copper electrodeposited in the composition of an electrolyte. The resistivity and peel strength were controlled using a range of electrolyte compositions. A lower resistivity and high flexibility were obtained when an electrolyte with 20 g/l of copper was used. However, a uniform surface was obtained when a high current density that exceeded $20mA/cm^2$ was applied, which was maintained at copper concentrations exceeding 40 g/l. Increasing sulfuric acid to >150 g/l decreased the peel strength and flexibility. The lowest resistivity and fine adhesion were detected at a $Cu^{2+}:H_2SO_4$ ratio of 50:100 g/l.

• 대한금속재료학회지
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• 제49권8호
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• pp.657-663
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• 2011

This study represents the results of the peel strength and surface morphology according to the preprocessing times of polyimide (PI) in a Cu/Ni/PI structure flexible copper clad laminate production process based on the polyimide. Field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to analyze the surface morphology, crystal structure, and interface binding structure of sputtered Ni, Cu, and electrodeposited copper foil layers. The surface roughness of Ni, Cu deposition layers and the crystal structure of electrodeposited Cu layers were varied according to the preprocessing times. In the RF plasma times that were varied by 100-600 seconds in a preprocessing process, the preprocessing applied by about 300-400 seconds showed a homogeneous surface morphology in the metal layers and that also represented high peel strength for the polyimide. Considering the effect of peel strength on plastic deformation, preprocessing times can reasonably be at about 400 seconds.

• 설비공학논문집
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• 제17권6호
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• pp.544-551
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• 2005

The flow characteristics have been numerically investigated for various shapes of the diffuser/nozzles which are used for a valveless micro-pump. The important parameters considered in this study are the throat width ($15\~120\mu$m), the taper angle ($3.15\~25.2^{\circ}$), and the diffuser length ( $600\~4,800\mu$m), and the size of the middle chamber ($1\~16mm^2$). To find the optimal values for these parameters, steady state calculations have been performed assuming the constant pressure difference between the inlet and exit of the flow For the taper angle and the throat width, it is found that there exists an optimum at which the net flow rate is the greatest. The optimal taper angle is in the range of $10\~20^{\circ}$ for all the pressure differences; and the throat width indicates an optimal value near $75\mu$m for the case of 35 kPa pressure difference. The net flow rate is also influenced by the size of the middle chamber. With decreasing chamber size, the net flow rate is reduced because of the interference between two streams flowing into the middle chamber. The unsteady pulsating flow characteristics for a micro-pump with a given diffuser/nozzle shape have been also investigated to show the validity of the steady state parametric study.

• Nano
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• 제13권10호
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• pp.1850124.1-1850124.12
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• 2018

$TiO_2$ films were deposited from oxygen/titanium tetraisopropoxide (TTIP) plasmas at low temperature by Helicon-PECVD at floating potential ($V_f$) or substrate self-bias of -50 V. The influence of titanium precursor partial pressure on the morphology, nanostructure and optical properties was investigated. Low titanium partial pressure ([TTIP] < 0.013 Pa) was applied by controlling the TTIP flow rate which is introduced by its own vapor pressure, whereas higher titanium partial pressure was formed through increasing the flow rate by using a carrier gas (CG). Then the precursor partial pressures [TTIP+CG] = 0:027 Pa and 0.093 Pa were obtained. At $V_f$, all the films exhibit a columnar structure, but the degree of inhomogeneity is decreased with the precursor partial pressure. Phase transformation from anatase ([TTIP] < 0.013 Pa) to amorphous ([TTIP+CG] = 0:093 Pa) has been evidenced since the $O^+_2$ ion to neutral flux ratio in the plasma was decreased and more carbon contained in the film. However, in the case of -50 V, the related growth rate for different precursor partial pressures is slightly (~15%) decreased. The columnar morphology at [TTIP] < 0.013 Pa has been changed into a granular structure, but still homogeneous columns are observed for [TTIP+CG] = 0:027 Pa and 0.093 Pa. Rutile phase has been generated at [TTIP] < 0:013 Pa. Ellipsometry measurements were performed on the films deposited at -50 V; results show that the precursor addition from low to high levels leads to a decrease in refractive index.

• 융합정보논문지
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• 제11권3호
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• pp.167-173
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• 2021

최근 폴리이미드가 기판으로 사용되어 유기발광다이오드 디스플레이가 구현된 폴더블 스마트폰이 출시되고 있다. 이와 같이 굽힘이 가능한 기판위에 다양한 전자소자를 제작하기 위한 관심이 증가하고 있기 때문에 본 논문에서는 굽힘성이 우수한 127㎛ 두께의 얇은 스테인리스 금속 기판을 이용하여 먼저 크롬을 코팅하고 알루미늄을 형성한 샘플과 알루미늄 구현 후 크롬을 증착한 2가지 샘플을 급속 열처리 장비를 이용하여 150도, 350도, 550도의 온도에서 각각 20분간 어닐링을 진행하여 표면의 형상을 관찰하였다. 고분해능 SEM과 nm까지 거칠기를 측정할 수 있는 AFM을 이용하여 표면에 대한 데이터를 추출하였다. 350도까지는 열처리하지 않은 샘플과 차이가 없지만, 550도에서는 결정립의 변화를 확인할 수 있다. 향후 본 실험 결과는 플렉서블 광전자분야로의 적용을 위해 전기전도도, 반사도와 같은 특성 분석 및 광소자 제작을 통해 금속 소재의 플렉서블 전자소자로의 적용 가능성을 모색할 것이다.