• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.456-456
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• 2010

CMOS 소자가 서브마이크론($0.1\;{\mu}m$) 이하로 스케일다운 되면서 단채널 효과(short channel effect), 게이트 산화막(gate oxide)의 누설전류(leakage current)의 증가와 높은 직렬저항(series resistance) 등의 문제가 발생한다. CMOS 소자의 구동전류(drive current)를 높이고, 단채널 효과를 줄이기 위한 가장 효율적인 방법은 소스 및 드레인의 얕은 접합(shallow junction) 형성과 직렬 저항을 줄이는 것이다. 플라즈마 도핑 방법은 플라즈마 밀도 컨트롤, 주입 바이어스 전압 조절 등을 통해 저 에너지 이온주입법보다 기판 손상 및 표면 결함의 생성을 억제하면서 고농도로 얕은 접합을 형성할 수 있다. 그리고 얕은 접합을 형성하기 위해 주입된 불순물의 활성화와 확산을 위해 후속 열처리 공정은 높은 온도에서 짧은 시간 열처리하여 불순물 물질의 활성화를 높여주면서 열처리로 인한 접합 깊이를 얕게 해야 한다. 그러나 접합의 깊이가 줄어듦에 따라서 소스 및 드레인의 표면 저항(sheet resistance)과 접촉저항(contact resistance)이 급격하게 증가하는 문제점이 있다. 이러한 표면저항과 접촉저항을 줄이기 위한 방안으로 실리사이드 박막(silicide thin film)을 형성하는 방법이 사용되고 있다. 본 논문에서는 (100) p-type 웨이퍼 He(90 %) 가스로 희석된 $PH_3$(10 %) 가스를 사용하여 플라즈마 도핑을 실시하였다. 10 mTorr의 압력에서 200 W RF 파워를 인가하여 플라즈마를 생성하였고 도핑은 바이어스 전압 -1 kV에서 60 초 동안 실시하였다. 얕은 접합을 형성하기 위한 불순물의 활성화는 ArF(193 nm) excimer laser를 통해 $460\;mJ/cm^2$의 에니지로 열처리를 실시하였다. 그리고 낮은 접촉비저항과 표면저항을 얻기 위해 metal sputter를 통해 TiN/Ti를 $800/400\;{\AA}$ 증착하고 metal RTP를 사용하여 실리사이드 형성 온도를 $650{\sim}800^{\circ}C$까지 60 초 동안 열처리를 실시하여 $TiSi_2$ 박막을 형성하였다. 그리고 $TiSi_2$의 두께를 측정하기 위해 TEM(Transmission Electron Microscopy)을 측정하였다. 화학적 결합상태를 분석하기 위해 XPS(X-ray photoelectronic)와 XRD(X-ray diffraction)를 측정하였다. 접촉비저항, 접촉저항과 표면저항을 분석하기 위해 TLM(Transfer Length Method) 패턴을 제작하여 I-V 특성을 측정하였다. TEM 측정결과 $TiSi_2$의 두께는 약 $580{\AA}$ 정도이고 morphology는 안정적이고 실리사이드 집괴 현상은 발견되지 않았다. XPS와 XRD 분석결과 실리사이드 형성 온도가 $700^{\circ}C$에서 C54 형태의 $TiSi_2$ 박막이 형성되었고 가장 낮은 접촉비저항과 접촉저항 값을 가진다.

• 한국세라믹학회지
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• 제49권6호
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• pp.620-624
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• 2012

The role of moisture remaining inside the deposition chamber during the formation of the cubic boron nitride (c-BN) phase in BN film was investigated. BN films were deposited by an unbalanced magnetron sputtering (UBM) method. Single-crystal (001) Si wafers were used as substrates. A hexagonal boron nitride (h-BN) target was used as a sputter target which was connected to a 13.56 MHz radiofrequency electric power source at 400 W. The substrate was biased at -60 V using a 200 kHz high-frequency power supply. The deposition pressure was 0.27 Pa with a flow of Ar 18 sccm - $N_2$ 2 sccm mixed gas. The inside of the deposition chamber was maintained at a moisture level of 65% during the initial stage. The effects of the evacuation time, duration time of heating the substrate holder at $250^{\circ}C$ as well as the plasma treatment on the inside chamber wall on the formation of c-BN were studied. The effects of heating as well as the plasma treatment very effectively eliminated the moisture adsorbed on the chamber wall. A pre-deposition condition for the stable and repeatable deposition of c-BN is suggested.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.69.1-69.1
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• 2010

We have fabricated organic photovoltaic cells (OPVs) with highly conductive poly 3,4-ethylenedioxythiophene : poly styrenesulfonate (PEDOT:PSS) layer as an anode without using transparent conducting oxide (TCO), which has been modified by adding some organic solvents like sorbitol (So), dimethyl sulfoxide (DMSO), N-methyl-pyrrolidone (NMP), dimethylformamide (DMF), and ethylene glycol (EG). The conductivity of PEDOT:PSS film modified with each additive was enhanced by three orders of magnitude. According to atomic force microscopy (AFM) study, conductivity enhancement might be related to better connections between the conducting PEDOT chains. TCO-free solar cells with modified PEDOT:PSS layer and the active layer composed of poly(3-hexylthiophene) (P3HT) and phenyl [6,6] C61 butyric acid methyl ester (PCBM) exhibited a comparable device performance to indium tin oxide (ITO) based organic solar cells. The power conversion efficiency (PCE) of the organic solar cells incorporating DMSO, So + DMSO and EG modified PEDOT:PSS layer reached 3.51, 3.64 and 3.77%, respectively, under illumination of AM 1.5 (100mW/$cm^2$).

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.624-630
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• 2006

ZnO deposition parameters are not independent and have a nonlinear and complex property. To propose a method that could verify and predict the relations of process variables, neural network was used. At first, ZnO thin films were deposited by using RF magnetron sputtering process with various conditions. Si, GaAs, and Glass were used as substrates. The temperature, work pressure, and RF power of the substrate were $50\sim500^{\circ}C$, 15 mTorr, and $180\sim210W$, respectively : the purity of the target was ZnO 4 N. Structural properties of ZnO thin films were estimated by using XRD (0002) peak intensity. The structure of neural network was a form of 4-7-1 that have one hidden layer. In training a network, learning rate and momentum were selected as 0.2, 0.6 respectively. A backpropagation neural network were performed with XRD (0002) peak data. After training a network, the temperature of substrate was evaluated as the most important parameter by sensitivity analysis and response surface. As a result, neural network could capture nonlinear and complex relationships between process parameters and predict structural properties of ZnO thin films with a limited set of experiments.

• 열처리공학회지
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• 제15권3호
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• pp.118-126
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• 2002

TiCN thin films were deposited on tool steels at $510^{\circ}C$ by PECVD from a $TiCl_4+N_2+CH_4+H_2+Ar$ gaseous mixture. The microstructures and preferred orientation were investigated. The micro-scratch tests were performed using a system equipped with an acoustic emission sensor. Critical loads were determined to evaluate the adhesion of TiCN to substrate. The influences of the microstructures of substrates, double layered coatings, and coatings after nitriding(duplex coating) were investigated. The experimental results showed that the microstructures of substrates and double layered coating did not affect the critical loads considerably. By the duplex coating, critical loads were not always increased. In some cases, duplex coatings decreased critical loads significantly despite of absence of black layer. In this study, we tried to relate the results of scratch test to the residual stress analysis. Nitriding before the coating reduces the tensile residual stress in the film, which gives rise to low critical load in scratch test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.163-164
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• 2006

ZnO deposition parameters are not independent and have a nonlinear and complex properties respectively. Therefore, finding optimal process conditions are very difficult and need to do many experiments. To predict ZnO deposition result, neural network was used. To gather training data, Si, GaAs, and Glass were used for substrates, and substrate temperature, work pressure, RF power were $50-500^{\circ}C$, 15 mTorr, and 180-210 W respectively, and the purity of target was ZnO 4N. For predicting the result of ZnO deposition process exactly, sensitivity analysis and drawing a response surface was added. The temperature of substrate was evaluated as a most important variable. As a result, neural network could verify the nonlinear and complex relations of variables and find the optimal process condition for good quality ZnO thin films.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.152-152
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• 2010

이종접합 태양전지에서 Intrinsic a-Si:H의 역할은 상당히 중요하다. Passivation 효과와 높은 Voc에 이르는 핵심적인 Layer이다. 본 연구는 Intrinsic a-Si:H Layer의 증착조건을 가변하여 최적의 Passivation 효과를 얻는데 목적이 있다. 웨이퍼는 n-Type $500\;{\mu}m$두께에를 사용하였다. Intrinsic a-Si:H Layer는 $SiH_4$ 가스와 $H_2$ 가스를 혼합하여 증착하게 되는데 혼합비는 1:5로 고정하였다. 증착두께는 이종접합 태양전지에서 필요한 5nm로 고정하였으며 증착장비는 PECVD를 이용하였다. PECVD는 VHF(60MHz)를 이용하였고 증착온도는 $200^{\circ}C$로 고정하여 진행하였다. 가변내용은 전극거리와 파워, 압력이다. 전극거리는 20mm에서 80mm까지 가변하였고 압력은 100mTorr에서 500mTorr까지 가변하였다. 파워는 플라즈마의 방정특성을 알아본 후 최소파워를 이용하여 증착하였다. 이는 증착 시 플라즈마에 의한 박막 손상을 최소화하기 위함이다. 측정은 QSSPC 방식으로 Carrier Lifetime과 Implied Voc를 측정하였으며 두께는 Ellipsometry를 이용하여 측정하였다. 전극거리 60mm에서 증착압력은 400mTorr이고 파워는 $14mW/cm^2$에서 가장 높은 Carrier Lifetime 과 Implied Voc를 나타내었다. Carrier Lifetime은 2.2ms이고 Implied Voc는 709mV를 달성 하였다. Carrier Lifetime이 높으면 Surface Recombination이 낮다는 의미이며 이는 고효율 이종접합 태양전지 제작에 있어서 직렬저항을 줄일 수 있는 필수적인 요소이다. Implied Voc는 이종접합 태양전지의 Voc에 직결된 인자로 이종접합 태양전지의 Voc를 예상할 수 있는 중요한 요소이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.241-241
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• 2007

We fabricated SmBCO coated conductors(CCs) on IBAD-MgO templates using co-evaporation method. IBAD-MgO templates consist of PLD-LMO/epi-MgO/IBAD-MgO/Ni-alloy and showed good in-plane texture of below FWHM 7 degree. Evaporation rates of Sm, Ba, and Cu were precisely controlled to get the optimum composition ratio after deposition process. To optimize the oxygen partial pressure of reaction region, wide range of the partial pressure was investigated from 1 mTorr to 15 mTorr. By reducing the oxygen partial pressure to 5mTorr, (103)grains in SmBCO layer have been increased. On the other hand, there were only (001)grains in SmBCO layer deposited at 15 mTorr $O_2$. Deposition temperature was also investigated from $600^{\circ}C\;to\;800^{\circ}C$ to make high Ic SmBCO CCs. SmBCO on IBAD MgO template showed that the Ic increased gradually at higher growth temperature to $800^{\circ}C$, which the highest Jc and Ic is $2.6\;MA/cm^2$ and 500 A/cm-w., respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1523-1525
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• 2003

Due to the rapid development of wireless networking system, researches on the communication devices are mainly focus on microwave frequency devices such as filters, resonators, and phase shifters. Among them, Film bulk acoustic resonator (FBAR) has been paid extensive attentions for their high performance. In this research, ZnO thin films were deposited by RF-magnetron sputtering on Al/$SiO_2$/Si wafer and then crystalline properties and surface morphology were examined. To measure crystalline structure and surface morphology X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were employed. It was showed that crystalline properties of ZnO thin films were strongly dependant on the deposition conditions. As increasing the deposition temperature and the deposition pressures, the peak intensities of ZnO(002) plane were increased until $300^{\circ}C$, then decreased rapidly. At the sputtering conditions of RF power of 213 W and working pressure of 15 m Torr, ZnO film had excellent c-axis orientation, surface morphology, and adhesion to the substrate. In conclusion we optimized smooth surface with very small grains as well as highly c-axis oriented ZnO film for FBAR applications.

• 센서학회지
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• 제6권4호
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• pp.328-336
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• 1997

HWE 방법에 의해 CdSe 박막을 (100)방향 Si 기판 위에 성장시켰다. 증발원과 기판의 온도를 각각 $600^{\circ}C$, $430^{\circ}C$로하여 성장시킨 CdSe 박막의 이중 결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)값이 380 arcsec로 가장 작았다. Van der Pauw 방법으로 Hall 효과를 측정하여 운반자농도의 In n 대 (1/T)에서 구한 활성화에너지는 0.19eV로 측정되었다. Hall 이동도의 온도 의존성은 30K에서 150K까지는 $T^{3/2}$에 따라 증가하여 불순물산란에 기인하고, 150K에서 293K까지는 $T^{-3/2}$에 따라 감소하여 격자산란에 기인한 것으로 고찰되었다. 광전도셀의 특성으로 spectral response, 최대 허용소비전력(MAPD), 광전류와 암전류(pc/dc)의 비 및 응답시간을 측정하였다. Cu 증기분위기에서 열처리한 광전도셀의 경우, 감도(${\gamma}$)는 0.99, pc/dc은 $1.39{\times}10^{7}$, 그리고 최대 허용소비전력(MAPD)은 335mW, 오름시간(rise time)은 10ms, 내림시간(decay time)은 9.5ms로 가장 좋은 광전도 특성을 얻었다.