• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.499-502
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• 2000

In this study, $\alpha$-Fe$_2$O$_3$thin films were deposited on $Al_2$O$_3$substrate by RF magnetron sputtering method from a $\alpha$-Fe$_2$O$_3$target(99.9%). The sputtering atmosphere was Ar and 80%Ar:20%O$_2$mixture in a total gas pressure of 1~3mTorr. As-deposited $\alpha$-Fe$_2$O$_3$thin films were heated to 300, 400, 500, $600^{\circ}C$ for 5hr in oxygen atmosphere. The structure and the morphology of $\alpha$-Fe$_2$O$_3$thin films were examined by scanning Electron microscopy(SEM) and the crystal structure was analyzed by X-Ray Diffractometer(XRD). The microstructure of the annealed $\alpha$-Fe$_2$O$_3$films exhibits rather gross particle and the grain size was less than 100nm. Since the grain size was very small, the gas sensitivity was expected to be improved.

• Journal of the Korean Vacuum Society
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• 제7권3호
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• pp.255-260
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• 1998

The ionized magnetron sputtering is very useful in filling of small metal contact or via in ULSI processing with very high ionization upto 80% based on incoming flux ratio. But fairly high sputtering gas pressure is required to get high ionization, which instead gives low deposition rate and diverse incoming neutral's angular distribution. The electron quenching by heavily sputtered metals and gas rarefaction were considered the main causes of decreased ionization in this process. RF pulsing of sputtering power was proposed to solve those two problems. The results showed that 10㎳/10 ㎳ and 100㎳/100 ㎳ of on/off pulsings were optimal pulse conditions from OES measurements and also XRD of deposited Ag film showed distinct change of (111) to (200) preferred orientation. These results were analysed in a view point of neutral gas heating and cooling by high power sputtering.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.184.1-184.1
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• 2015

RF magnetron sputtering법을 이용하여 IGZO박막을 RF power 100W로 일정하게 유지시켜, 열처리 변화에 따른 구조적, 전기적, 광학적 특성 분석을 연구하였다. IGZO 타겟은 $In_2$ $O_3$, $Ga_2$ $O_3$, ZnO 분말을 각각 1:1:2 mol% 조성비로 혼합하여 소결한 타겟을 사용하였고, $20mm{\times}20mm$ XG glass 기판위에 IGZO박막을 증착하였다. sputtering의 조건은 base pressure $2.0{\times}$10^-6Torr, working pressure $2.0{\times}$10^-2Torr, RF power 100 W, 증착온도는 실온으로 고정, 증착된 박막은 Annealing장비로 $500^{\circ}C$, $700^{\circ}C$, $800^{\circ}C$로 열처리를 하였다. XRD 분석 결과 열처리 $700^{\circ}C$부터 2theta=31.4도에서 peak intensity가 증가하며 결정화가 진행되는 것을 확인하였다. AFM분석 결과 열처리 $700^{\circ}C$에서 최소 0.31 Roughness를 갖는 것을 확인하였고, Hall 측정 결과 열처리 $700^{\circ}C$에서 carrier concentration $4.91{\times}$10^19cm^-3, Mobility 14.4cm^2/V-s, Resistivity $8.7{\times}$10^-5${\Omega}-cm$로 확인하였으며, UV-Visible-NIR을 이용하여 열처리 한 모든 IGZO박막은 가시광선 영역에서 평균 85%이상의 광 투과성을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.374-374
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• 2009

We have fabricated pure YBCO films and $BaZrO_3$ doped ones on $CeO_2$ buffered YSZ single crystal substrates using rf-sputtering method. In this work, pure YBCO and 2 vol% BZO doped YBCO target were used to investigate the flux pinning properties of BZO doped YBCO films compared to undoped ones. BZO nanodots within the superconducting materials was known to comprise the self-assembled columnar defects along the c-axis from the bottom of YBCO films up to the top surface, thus can be a very strong pinning sites in the applied magnetic field parallel to them. We will discuss the possibility of growing self-assembled columnar defects in the rf-sputtering method. It is speculated that BZO and YBCO phases can separate and BZO form nanodots surrounded by YBCO epitaxial layers and continuous phase separation and ordering between these two materials, which was well studied in Pulsed Laser Deposition method. For this purpose, some severe experimental conditions such as on-axis sputtering, shorter target-substrate distance, high rf-power, etc was adopted and their results will be presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.387-387
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• 2010

최근 ZnO 박막은 투명 박막, 태양전지, LED 등으로의 응용을 위한 새로운 기능성 박막으로 활발히 연구되어 지고 있다. ZnO 기반의 투명 박막 트랜지스터는 상온에서 증착 가능하여 유리기판을 이용한 광학소자와 플라스틱 기판을 이용한 플럭서블 소자 같은 차세대 전자소자를 구현 할 수 있다. 본 연구에서는 RF Magnetron Sputtering System을 이용하여 coming 1737 유리기판 위에 ZnO 박막을 공정압력에 따라 증착하고, 투명 반도체에 적합한 활용을 위한 구조적, 광학적 분석을 실시하였다. 박막 증착 조건은 초기 압력 $1.0{\times}10^{-6}$Torr, RF 파워는 100W, Ar 유량은 100sccm, 그리고 증착온도는 상온이었다. 증착 압력은 $7.0{\times}10^{-3}$, $2.0{\times}10^{-2}$, $7.0{\times}10^{-2}$Torr로 변화시켰다. 표면 분석 (SEM, AFM) 결과 증착압력이 고진공으로 변화함에 따라 결정립들이 감소하였고 RMS roughness값이 낮아졌다. 그리고 XRD 분석을 통해 피크강도는 증가하고 FWHM은 감소함을 보이고 있는데 이는 결정성이 좋아짐을 나타낸다. 그리고 광학 투과도를 통해 가시광 영역에서의 높은 투과도(85% 이상)을 확인하였고, 고진공으로 변화함에 따라 밴드갭이 넓어지는 것을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.146-147
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• 2008

In this paper we report upon an investigation into the effect of sputter RF power on the electrical properties of Gallium doped zinc oxide (ZnO:Ga) film. Structural, electrical and optical properties of the ZnO:Ga films were investigation in terms of the sputtering power. Working pressure fixed in 5 mtorr and RF powers the variable did with 50~100 W. The result, We were able to without substrate temperature obtain resistivity of $9.3\times10^{-4}{\Omega}cm$ and optical transmittance of 90%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제18권2호
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• pp.164-168
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• 2005

Piezoelectric ZnO thin films were for the first time formed on SiO$_2$/Si(100) substrate using 2-step deposition, atomic layer deposition(ALD) and RF magnetron sputtering deposition, for film bulk acoustic resonator(FBAR) applications. The ZnO buffer layer by ALD was deposited using alternating diethyl zinc(DEZn)/$H_2O$ exposures and ultrahigh purity argon gas for purging. The ZnO films by 2-step deposition revealed stronger c-axis-preferred orientation and smoother surface than those by the conventional RF sputtering method. The solidly mounted resonator(SMR)-typed FBAR fabricated by using 2-step deposition method revealed higher quality factor of 580 and lower return loss of -17.35dB. Therefore the 2-step deposition method in this study could be applied to the FBAR device fabrication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.143-147
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• 2002

In this paper, we investigated the deposition condition of Bragg reflector formation that will be expected to play an important role in future FBAR device applications. The thin films were deposited using an RF/DC magnetron sputtering technique. The material characteristics such as deposition rates, grain structures and surface roughnesses of the deposited silicon dioxide (SiO$_2$) and tungsten (W) films were investigated for various deposition conditions. As a result, it was found that the deposition condition could significantly affect the material characteristics of the deposited films and also the optimization of the deposition process is essentially important to obtain the desirable Brags reflector structure consisted of high-quality in films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제11권7호
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• pp.527-534
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• 1998

Thin film deposition of InN, which is a less-studied III-nitride compound semiconductor because of the difficulty if crystal growth, was performed by rf reactive sputtering method using In target and $N_2$reactive gas. The structrual, electrical, and optical properties of the produced films were measured and disussed according to the sputtering parameters such as deposition pressure, rf power, and substrate temperature. From the result of deposition pressure, rf power, and substrate temperature, we could obtain optimal conditions of 5m Torr, 60W, $60^{\circ}C$ for preparing InN thin film with high crystallinity, low carrier concentration, and high Hall mobility. The carrier concentration, Hall mobility, and optical bandgap of the fabricated InN thin films at optimal condition were $6.242\times10^{18}cm^{-3}, 212.526cm^2/V\cdot$ｓ, and 1.912eV, respectively.

• Journal of the Korean Vacuum Society
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• 제11권1호
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• pp.1-7
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• 2002

We deposited $Ba_{0.5}Sr_{0.5}TiO_3$(BST) thin-films on Pt/Ti/$SiO_2$/Si substrates using RF magnetron sputtering method. A Substrate temperature was fixed at room temperature, while working gas flow ratio and RF Power were changed from 90:10 to 60:40 and 50 W, 75 W respectively. Also after BST thin films were deposited, we performed annealing in oxygen atmosphere using Rapid Thermal Annealing. For capacitor application we deposited Pt using E-beam evaporator of UHV system. In a structural property study through XRD measurement we found that crystallization depends on annealing rather than working gas ratio or and RF Power. Electrical properties showed relatively superior characteristic on the annealed sample with 50 W of RF Power.