• 한국재료학회지
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• 제28권3호
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• pp.159-165
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• 2018

In order to increase the efficiency of the sputtering method widely used in thin film fabrication, a dc sputtering apparatus which supplies both high frequency and magnetic field from the outside was fabricated, and cobalt thin film was fabricated using this apparatus. The apparatus can independently control the applied voltage, the target-substrate distance, and the target current, which are important parameters in the sputtering method, so that a stable glow discharge is obtained even at a low gas pressure of $10^{-3}$ Torr. The fabrication conditions using the sputtering method were mainly performed in $Ar+O_2$ mixed gas containing about 0.6 % oxygen gas under various Ar gas pressures of 1 to 30 mTorr. The microstructure of Co thin films deposited using this apparatus was examined by electron diffraction pattern and X-ray techniques. The magnetic properties were investigated by measuring the magnetization curves. The microstructure and magnetic properties of Co thin films depend on the discharge gas pressure. The thin film fabricated at high gas pressure showed a columnar structure containing a large amount of the third phase in the boundary region and the thin film formed at low gas pressure showed little or no columnar structure. The coercivity in the plane was slightly larger than that in the latter case.

• Progress in Superconductivity
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• 제4권2호
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• pp.153-156
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• 2003

We have studied fabrication of $MgB_2$ thin film on $SrTiO_3$ (001) and r-cut $A1_2$$O_3$ substrates by rf magnetron sputtering method using and $ MgB_2$ single target and two targets of Mg and B, respectively. Based on P -T phase diagram of $MgB_2$ and vapor pressure curves of Mg and B, a three-step process was employed. B layer was deposited at the bottom to enhance the film adhesion to the substrate. Secondly, co-sputtering of Mg and B was done. Finally, Mg was sputtered on top to compensate fur the loss of Mg during annealing. Subsequently, $MgB_2$ films were in-situ annealed in various conditions. The sample fabricated using the three-step process showed $T_{c}$ of 24 K and formation of superconducting $MgB_2$ phase was confirmed by XRD spectra. In case of co-sputtering deposition, $T_{c}$ depended on annealing time and argon pressure. However, those made by single-target sputtering showed non-superconducting behavior or low transition temperature, at best.est.

• 한국진공학회지
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• 제7권3호
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• pp.255-260
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• 1998

Ionized magnetron sputtering은 high density plasma를 사용하여 스퍼터된 입자의 이온화율을 기판에서의 플럭스 기준으로 80%이상까지 증대시킬 수 있는 방법으로 반도체 소자의 아주 작은 홀이나 via contact등을 채울 수 있는 아주 유용한 수단이나 가스의 압력 이 30mTorr 이상으로 상당히 높아야만 이온화율이 높게 유지되어 스퍼터 증착 속도가 느려 지고 중성입자의 각도 분포가 넓어지는 단점이 있다. 그 원인이 스퍼터된 입자들에 의한 전 자 온도의 급격한 감소와 타겟 주변에서의 가스 희귀화 현상에 있다고 보고 이를 보완하고 자 스퍼터 전력을 펄스화 하는 방법을 고안하여 실험하였다. 그 결과 펄스의 on/off time이 10ms/10ms, 100ms/100ms에서 가장 높은 이온화율을 가시광 분광 결과에서 보였으며 실제 로 Ag의 XRD결과 (111)에서 (200)으로 우선 방위의 현격한 변화가 관찰되었다. 이를 고전 력 스퍼터링에 의한 중성 가스 가열과 냉각의 측면에서 해석하였다.

• 한국전기전자재료학회논문지
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• 제19권4호
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• pp.373-378
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• 2006

We report on plasma damage free-sputtering technologies for organic light emitting diodes (OLEDs), organic thin film transistor (OTFT) and flexible displays by using a box cathode sputtering (BCS) method. Specially designed BCS system has two facing targets generating high magnetic fields ideally entering and leaving the targets, perpendicularly. This target geometry allows the formation of high-density plasma between targets and enables us to realize plasma damage free sputtering on organic layer without protection layer against plasma. The OLED with Al cathode prepared by BCS shows electrical and optical characteristics comparable to OLED with thermally evaporated Mg-Ag cathode. It was found that OLED with Al cathode layer prepared by BCS has much lower leakage current density ($1{\times}10^{-5}\;mA/cm^2$ at -6 V) than that $(1{\times}10^{-2}{\sim}-10^0\;mA/cm^2)$ of OLED prepared by conventional DC sputtering system. This indicates that BCS technique is a promising electrode deposition method for substituting conventional thermal evaporation and DC/RF sputtering in fabrication process of organic based optoelectronics.

• 한국재료학회지
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• 제24권4호
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• pp.207-213
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• 2014

Flexible $BaTiO_3$ films as dielectric materials for high energy density capacitors were deposited on polyethylene terephthalate (PET) substrates by r.f. magnetron sputtering. The growth behavior, microstructure and electrical properties of the flexible $BaTiO_3$ films were dependent on the sputtering pressure during sputtering. The RMS roughness and crystallite size of the $BaTiO_3$ increased with increasing sputtering pressure. All $BaTiO_3$ films had an amorphous structure, regardless of the sputtering pressures, due to the low PET substrate temperature. The composition of films showed an atomic ratio (Ba:Ti:O) of 0.9:1.1:3. The electrical properties of the $BaTiO_3$ films were affected by the microstructure and roughness. The $BaTiO_3$ films prepared at 100 mTorr exhibited a dielectric constant of ~80 at 1 kHz and a leakage current of $10^{-8}A$ at 400 kV/cm. Also, films showed polarization of $8{\mu}C/cm^2$ at 100 kV/cm and remnant polarization ($P_r$) of $2{\mu}C/cm^2$. This suggests that sputter deposited flexible $BaTiO_3$ films are a promising dielectric that can be used in high energy density capacitors owing to their high dielectric constant, low leakage current and stable preparation by sputtering.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1764-1766
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• 1998

One of the most important problems in the development of AC PDP is to make long life and more stable panels. It is well known that the life time of a panel strongly depends on the sputtering-resistant property of the protecting layer such as MgO. However, the sputtering rate is so low that it is very difficult to measure the sputtering-resistant property of MgO. This paper describes a high speed measurement technique to test the sputtering-resistant property of MgO thin film by the R.F. magnetron sputtering. In this case the MgO sample has been used as a target of sputtering process. Moreover, the MgO surface changed by ion-bombarding sputtering are also discussed with SEM photoes.

• Journal of Information Display
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• 제8권3호
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• pp.5-10
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• 2007

Twin target sputtering (TTS) system with a configuration of vertically parallel facing Al targets and a substrate holder perpendicular to the Al target plane has been designed to realize a direct Al cathode sputtering on organic light emitting diodes (OLEDs). The TTS system has a linear twin target gun with ladder type magnet array for effective and uniform confinement of high density plasma. It is shown that OLEDs with Al cathode deposited by the TTS show a relatvely lower leakage current density $({\sim}1{\times}10^{-5}mA/cm^2)$ at reverse bias of -6V, compared to that ($1{\times}10^{-2}{\sim}10^{-3}$ $mA/cm^2$ at -6V) of OLEDs with Al cathodes grown by conventional DC magnetron sputtering. In addition, it was found that Al cathode films prepared by TTS were amorphous structure with nanocrystallines due to low substrate temperature. This demonstrates that there is no plasma damage caused by the bombardment of energetic particles. This indicates that the TTS system with ladder type magnet array could be useful plasma damage free deposition technique for direct Al cathode sputtering on OLEDs or flexible OLEDs.

• 한국표면공학회지
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• 제37권1호
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• pp.5-12
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• 2004

The enhancement of adhesion for Cu film on polycarbonate (PC) surface with the $Ar/O_2$ gas plasma treatment and dc-bias sputtering was studied. The plasma treatment with this reactive mixture changes the chemical property of PC surface into hydrophllic one, which is shown by the variation of contact angle with surface modification. The micro surface roughness that also gives the high adhesive environment is increased by the $Ar/O_2$ gas plasma treatment. These results were observed distinctly from the atomic force microscopy (AFM). The negative substrate dc-bias effect for the Cu adhesion on PC was also investifated. Accelerated $Ar^{+}$ lons in sheath area of anode bombard the bare surface of PC during initial stage of dc bias sputtering. PC substrate. therefore, has severe roughen and hydrophilic surface due to the physical etching process with more activated functional group. As dc-bias sputtering process proceeds, morphology of Cu film shows better step coverage and dense layer. The results of peel test show the evidence of superiority of bias sputtering for the adhesion between metal Cu and PC.C.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.134-134
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• 2010

Ga-In-Zn-O 물질은 비정질상태에서 높은 전하 운동성을 가지고 있으며 차세대 투명전극 thin film transistor 대안 소재로 각광받고 있다. 그런데 이 물질은 ion sputtering에 따라 전기적인 특성에 큰 변화가 관찰되고 있으며, 이는 표면에서의 화학적 상태가 전기적 특성을 좌우할 것이라는 것을 의미한다. 또한 보다 안정적이고 신뢰적인 소자를 구현하기 위해서는 ion sputtering에 의한 표면에서의 화학적 특성 변화를 이해하는 것이 매우 중요하다는 것을 의미한다. 본 연구에서는 $Ga_2O_3:In_2O_3$:ZnO의 비율이 각각 1:1:1, 2:2:1, 3:2:1 그리고 4:2:1인 시료를 $Ne^+$이온을 이용하여 sputtering하면서 표면에 민감한 분광분석 기법인 x-ray photoelectron spectroscopy와 x-ray absorption spectroscopy를 이용하여 분광정보의 변화들을 연구하였다. 실험에 의하면, Ga 3d의 양에 비해서 In 4d, Zn 3d의 양은 sputtering 시간에 따라서 각 각 양이 줄어들었으며, 전체적으로 보다 산화가가 높은 경향을 보였으며, valence band maximum 근처에 subgap state를 형성하는 것을 관찰하였다. 또한 sputtering을 계속하는 경우 In 3d, In 4d, 및 Fermi energy 근처에 metallic state가 형성되는 것을 관찰하였다. 이러한 subgap state와 metallic state의 관측은 각기 sputtering에 따라서, 아직 명확하지는 않지만, surface state의 형성 및/혹은 oxygen interstitial의 형성 그리고 metallic In의 형성 및/혹은 oxygen defect의 형성이 이루어지는 것을 의미한다.

• 한국재료학회지
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• 제12권6호
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• pp.452-457
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• 2002

Titanium oxide films were prepared by RF reactive magnetron sputtering. The effect of sputtering conditions on structural and optical properties was investigated systemically as a function of sputtering pressure(5~20 mTorr) and $O_2/Ar$ flow ratio(0.08~0.4). The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. At low sputtering pressure and $O_2/Ar$ flow ratio, the films had preferred orientations along [101] and [200] directions. As the sputtering pressure and $O_2/Ar$ flow ratio increased, the intensity of the 101 and 200 diffraction peaks decreased gradually. The microstructure of the sputtered films showed the fine grain size (20nm~50nm) and columnar microcrystals perpendicular to the substrate. With increasing the sputtering pressure and decreasing $O_2/Ar$ flow ratio, the sputtered films showed the more porous columnar structure. XPS analysis showed that stoichiometric $TiO_2$ films were deposited at 7 mTorr sputtering pressure and 0.2 $O_2/Ar$ flow ratio. The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. Ellipsometeric analysis showed that the refractive index increased from 2.32 to 2.46 as the sputtering pressure decreased. The packing density calculated using the refractive index varied from 0.923 to 0.976, indicating that $TiO_2$films became denser as the sputtering pressure decreased.