• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.27-28
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• 2014

투명전극이란 전기 전도도를 갖는 동시에 가시광선 영역에서 빛을 투과하는 성질을 가지는 소재이다. 일반적으로 가시광선 영역(380nm~780nm)에서 80%이상의 광 투과도를 가지며, 비저항이 $10^{-3}{\Omega}{\cdot}cm$ 이하, optical band gap 이 3.3 eV 이상인 물질을 TCO(Transparent Conducting oxide)라고 한다. 현재까지 국내의 TCO 관련 연구는 터치패널, 디스플레이, 태양전지 등 광전자분야에서 가장 널리 사용되고 있는 ITO(Sn:In2O3)에 치중되어 있으며, 관련 연구도 거의 디스플레이 맞춤형 연구개발이 주류를 이루어왔다. ITO가 전기전도성이 우수하고 동시에 가시광선 영역에서의 투과율도 80%이상으로 전기적, 광학적 특성이 우수하다는 장점을 가지고 있으나, In의 희소성으로 인한 고가격, 유독성, 접착력 문제 때문에 이를 대체하기 위해 제조원가가 ITO에 비하여 월등히 저렴하고 내화학성과 내마모성이 우수하면서도, 가시광선 영역에서의 광투과율이 80%이상으로 좋다는 $SnO_2$에 관한 연구가 활발히 진행되어 왔다. 적절한 dopant를 첨가하여 $SnO_2$자체의 높은 광학적 투과도를 유지하면서 전기전도성을 더 높일수 있고, 투명전극이 가져야 할 고온 안정성을 가지고 있으며 비독성이고 수소 플라즈마에 대한 내성이 더 클 뿐만 아니라 저온에서 성장이 가능하다. $SnO_2$의 전기 전도도를 높이기 위한 Al, In, Ga, B와 같은 3족 원소가 $SnO_2$의 n형 dopant로 널리 사용되고 있다. 그 중 Al은 반응성이 커서 박막 증착 중에 산화되기 쉬운 반면, 전기적 특성 및 광학적 특성의 향상을 이룰 수 있다. 본 연구에서는 Rf Sputtering법을 사용하여 quartz기판 위에 다층박막 형태의 투명전도막을 제작한 후, 열처리를 수행, 이에 의한 다층박막 내 계면간 상호확산 현상을 이용하여 투명 전도막의 특성변화를 관찰하였다. 박막의 구조적 특성은 XRD장비를 사용하여 분석하였으며, 전기적, 광학적 특성은 각각 표면저항기, 홀 측정 장비, 그리고 UV-VIS-NI를 사용하여 확인하였다.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.30-34
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• 2019

We analyzed how the features in plasma information based virtual metrology (PI-VM) for SiO₂ etching depth with variation of 5% contribute to the prediction accuracy, which is previously developed by Jang. As a single feature, the explanatory power to the process results is in the order of plasma information about electron energy distribution function (PI_EEDF), equipment, and optical emission spectroscopy (OES) features. In the procedure of stepwise variable selection (SVS), OES features are selected after PI_EEDF. Informative vector for developed PI-VM also shows relatively high correlation between OES features and etching depth. This is because the reaction rate of each chemical species that governs the etching depth can be sensitively monitored when OES features are used with PI_EEDF. Securing PI_EEDF is important for the development of virtual metrology (VM) for prediction of process results. The role of PI_EEDF as an independent feature and the ability to monitor variation of plasma thermal state can make other features in the procedure of SVS more sensitive to the process results. It is expected that fault detection and classification (FDC) can be effectively developed by using the PI-VM.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.35-39
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• 2019

Effect of Ge₂Sb₂Te₅ (GST) chalcogen composition on plasma induced damage was investigated by using Ar ions and F radicals. Experiments were carried out with three different modes; the physical etching, the chemical etching, and the ion-enhanced chemical etching mode. For the physical etching by Ar ions, the sputtering yield was obtained according to ion bombarding energy and there was no change in GST composition ratio. In the plasma mode, the lowest etch rate was measured at the same applied power and there was also no plasma induced damage. In the ion-enhanced chemical etching conditions irradiated with high energy ions and F halogen radicals, the GST composition ratio was changed according to the density of F radicals, resulting in higher roughness of the etched surface. The change of GST composition ratio in halogen plasma is caused by the volatility difference of GST-halogen compounds with high energy ions over than the activation energy of surface reactions.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.32-37
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• 2019

Titanium dioxide ($TiO_2$) is a promising dielectric material in the semiconductor industry for its high dielectric constant. However, for utilization on Si substrate, $TiO_2$ film meets with a difficulty due to the large leakage currents caused by its small conduction band energy offset from Si substrate. In this study, we propose an in-situ plasma oxidation process in plasma-enhanced atomic layer deposition (PE-ALD) system to form an oxide barrier layer which can reduce the leakage currents from Si substrate to $TiO_2$ film. $TiO_2$ film depositions were followed by the plasma oxidation process using tetrakis(dimethylamino)titanium (TDMAT) as a Ti precursor. In our result, $SiO_2$ layer was successfully introduced by the plasma oxidation process and was used as a barrier layer between the Si substrate and $TiO_2$ film. Metal-oxide-semiconductor ($TiN/TiO_2/P-type$ Si substrate) capacitor with plasma oxidation barrier layer showed improved C-V and I-V characteristics compared to that without the plasma oxidation barrier layer.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.61-66
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• 2021

In this study, we studied the alternative of plasma resistant ceramic parts that constitute plasma chambers in the semiconductor dry etching process. MgO-Al₂O₃-SiO₂(MAS) glass was made of 13 types of glass using the Design Of Experiments(DOE) and the effect on thermal properties such as glass transition temperature and crystallization temperature depending on the content of each composition and etching resistance to CF₄/O₂/Ar plasma gas. MAS glass showed excellent plasma resistance and surface roughness up to 20 times higher than quartz glass. As the content of Al₂O₃ and MgO increases, the plasma resistance is improved, and it has been confirmed that it has an inverse relationship with SiO₂.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.72-77
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• 2021

The radial distribution of etch rate was analyzed using the ion energy flux model in VHF-CCP. In order to exclude the effects of polymer passivation and F radical depletion on the etching. The experiment was performed in Ar/SF6 plasma with an SF6 molar ratio of 80% of operating pressure 10 and 20 mTorr. The radial distribution of Ar/SF6 plasma was diagnosed with RF compensated Langmuir Probe(cLP) and Retarding Field Energy Analyzer(RFEA). The radial distribution of ion energy flux was calculated with Bohm current times the sheath voltage which is determined by the potential difference between the plasma space potential (measured by cLP) and the surface floating potential (by RFEA). To analyze the etch rate uniformity, Si coupon samples were etched under the same condition. The ion energy flux and the etch rate show a close correlation of more than 0.94 of R² value. It means that the etch rate distribution is explained by the ion energy flux.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.161-166
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• 2021

Errors in the semiconductor process are generated by a change in the state of the equipment, and errors usually arise when the state of the equipment changes or when parts that make up the equipment have flaws. In this investigation, we anticipated that aging of the mass flow controller in the plasma enhanced chemical vapor deposition SiO2 thin film deposition method caused a minute flow rate shift. In seven cases, fourier transformation infrared film quality analysis of the deposited thin film was used to characterize normal and pathological processes. The plasma condition was monitored using optical emission spectrometry data as the flow rate changed during the procedure. Preprocessing was used to apply the collected OES data to the artificial immune system algorithm, which was then used to process diagnosis. Through comparisons between datasets, the learning algorithm compared classification accuracy and improved the method. It has been confirmed that data characterized as a normal process and abnormal processes with differing flow rates may be discriminated by themselves using the artificial immune system data mining method.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.57-62
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• 2022

The plasma resistance of multi-component glasses containing La, Gd, Ti, Zn, Y, Zr, Nb, and Ta was analyzed in this study. The plasma etching was performed via inductively coupled plasma-reactive ion etching (ICP-RIE) using CF₄/O₂/Ar mixed gas. After the reaction, the glass with a low fluoride sublimation temperature and high content of P, Si, and Ti elements showed a high etching rate. On the other hand, the glass containing a high fluoride sublimation temperature component such as Ca, La, Gd, Y, and Zr exhibited high plasma resistance because the etch rate was lower than that of sapphire. Glass with low plasma resistance increased surface roughness after etching or nanoholes were formed on the surface, but glass with high plasma resistance showed little change in surface microstructure. Thus, the results of this study demonstrate the potential for the development of plasma-resistant glasses (PRGs) with other compositions besides alumino-silicate glasses, which are conventionally referred to as plasma-resistant glasses.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.12-16
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• 2012

Although silver is used for T-OLED (Top emitting organic Light-Emitting Diode) as reflective anode, it is not an ideal material due to its low work function. Thus, we study the effect of annealing and atmospheric pressure plasma treatment on Ag film that increases its work function by forming the thin silver oxide layer on its surface. In this study, we deposited silver on glass substrate using RF sputtering. Then we treated the Ag samples annealing at $300^{\circ}C$ for 30 minutes in atmosphere or treating the atmospheric plasma treatment for 30, 60, 90, 120s, respectively. We measured the change of the mechanical properties and the potential value of surface with each one at a different treatment type and time. We used nano-indenter system and KPFM (Kelvin Probe Force Microscopy). KPFM method can be measured the change of surface potential. The nanoindenter results showed that the plasma treatment samples for 30s, 120s had very low elastic modulus, hardness and Weibull modulus. However, annealed sample and plasma treated samples for 60s and 90s had better mechanical properties. Therefore, plasma treatment increases the uniformity thin film and the surface potential that is very effective for the performace of T-OLED.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.436-441
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• 2011

Metal coating with several nanometer thickness was applied on the carbon nanotubes (CNTs) in order to improve electron emission characteristics and emission reliability for the potential applications in the area of various electron sources and displays. CNTs were grown on the 2-nm thick Invar (52% Fe, 42% Ni, 6% Co alloy)-catalized Si substrate by using plasma-enhanced chemical vapor deposition at $450^{\circ}C$. In order to reduce the spatial density of densely packed CNTs, as-grown CNTs were partly etched back by $N_2$ plasma and subsequently coated with 5~150 nm thick Ti by a sputtering method. 5 nm thick Ti-coated CNTs produced four times higher emission current density at the electric field of 6 V/${\mu}m$ and much lower emission current fluctuation, compared with the as-grown CNTs. These improved emission properties are mainly due to not only the work function of Ti (4.3 eV) lower than that of pristine CNTs (5 eV), but also lower contact resistance and better adhesion between CNT emitters and substrate accomplished by Ti coating.