• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.171-179
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• 2019

We have developed a numerical model to analyze flow dynamics and heat transfer characteristics of the cooling water in a circular rotating magnetron cathode by a moving boundary grid method realized in a commercial multiphysics package, CFD-ACE+. The numerical model is composed of a target, dual mass rotating cathode and cooling water connections. When the inlet and outlet of the cooling water are offset by the same distance from the rotation axis, the temperature at the center is higher by $50^{\circ}C$ at maximum. At 5 mm away from the target surface, the temperature profile showed typical center high characteristic. At heat input of 30 kW, the maximum temperature change of the cooling water hits $6^{\circ}C$ within 0.5 sec under 60 rpm. With a cooling water configuration of center in/edge out, the temperature of the center region of the target gets lowered. Within 100 seconds of plasma operation time, the cooling water temperature keeps getting higher.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.179.1-179.1
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• 2013

Cylindrical Rotating Magnetron Sputtering Cathode (이하 Rotary Cathode)는 기존에 사용 되던 rectangular type 보다 Target 사용 효율이 높다는 큰 이점을 가지고 있다. 높은 Target 사용 효율은 비용 절감 효과와 직접적으로 관련 된다. 이번 연구는 3D Plasma simulation(PIC-MCC)을 통한 Target 사용 효율 80% 이상의 Rotary Cathode 개발을 목적으로 한다. Plasma simulation에 External Magnetic fields를 접목하여 Electron의 이동 궤적을 제어하였고, 생성된 Ion (Ar+)의 밀도 및 속도로 Plasma의 안정성과 Erosion 계산 구간을 선정 하였다. Target Erosion Profile은 Sputtering yield Data와 Target에 충돌한 Ion 정보를 사용하여 산출 하였으며, Sputtered Particles의 Deposition Profile은 계산된 Target Erosion Profile과 The cosine law of emission을 이용하여 계산 하였다. 실험 조건은 Plasma simulation의 초기조건 바탕으로 하여 2G size의 ITO Target을 대상으로 실험 하였다. 비 Erosion 영역 최소화하기 위해 Magnet Length를 변경하여 제작 적용 하였다. Simulation 계산 시간의 제약으로 인하여 simulation에서 생성된 최대 이온 밀도는 일반적으로 알려진 값 보다 적게 계산 되었지만, Simulation으로 예측한 Erosion Profile 및 Deposition Profile은 실험 값과 유사한 형태를 나타났으며, 실험 결과는 Target 사용 효율 80%이상의 결과를 보였다.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.296-300
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• 2003

Extended cylindrical magnetron sputtering system with rotating 600-mm long and 90-mm diameter graphite cathode and pulsed power supply voltage generator were developed and fabricated. Time-dependent Langmuir probe characteristics as well as carbon films thickness were measured. It was shown that ratio of ions flux to carbon atoms flux for pulsed magnetron discharge mode was equal to $\Phi_{i}$ $\Phi$sub C/ = 0.2. It did not depend on the discharge current in the range of $I_{d}$ / = 10∼60 A since both the plasma density and the film deposition rate were found approximately proportional to the discharge current. In spite of this fact carbon film structure was found to be strongly dependent on the discharge current. Grain size increased from 100 nm at $I_{d}$ = 10∼20 A to 500 nm at $I_{d}$ = 40∼60 A. To deposit fine-grained hard nanocrystalline or amorphous carbon coating current regime with $I_{d}$ = 20 A was chosen. Pulsed negative bias voltage ($\tau$= 40 ${\mu}\textrm{s}$, $U_{b}$ = 0∼10 ㎸) synchronized with magnetron discharge pulses was applied to a substrate and voltage of $U_{b}$ = 3.4 ㎸ was shown to be optimum for a hard carbon film deposition. Lower voltages were not sufficient for amorphization of a growing graphite film, while higher voltages led to excessive ion bombardment and effects of recrystalization and graphitization.

• Journal of the Semiconductor & Display Technology
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• v.2 no.3
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• pp.19-23
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• 2003

Extended unbalanced magnetron sputtering system based on the cylindrical magnetron with a rotating cathode was developed. The unbalanced configuration of magnetic field was realized by means of additional lines of permanent magnets, placed along both sides of a 89 mm outer diameter and 600 mm long cylindrical cathode. The performance of the unbalanced magnetron was assessed in terms of the ion current density and the ion-to-atom ratio incident at the substrate. Furthermore, the paper presents the comparison of the internal plasma parameters, such as the electron temperature, electron density, plasma and floating potentials, measured by a Langmuir probe in various positions from the cathode, for conventional and unbalanced constructions of the cylindrical magnetron. The plasma density and ion current density are about 3-5 times higher than those of conventional one, in the unbalanced magnetron in a 0.24 Pa Ar atmosphere with a DC cathode power of 3 kW.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.55.1-55.1
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• 2010

Cost efficient and large area deposition of superior quality $Al_2O_3$ doped zinc oxide (AZO) films is instrumental in many of its applications including solar cell fabrication due to its numerous advantages over ITO films. In this study, AZO films were prepared by a highly efficient rotating cylindrical dc magnetron sputtering system using AZO target, which has a target material utilization above 80%, on glass substrates in argon ambient. A detailed analysis on the electrical, optical and structural characteristics of AZO thin films was carried out for solar cell application. The properties of films were found to critically depend on deposition parameters such as sputtering power, substrate temperature, working pressure, and thickness of the films. A low resistivity of ${\sim}5.5{\times}10-4{\Omega}-cm$ was obtained for films deposited at 2kW, keeping the pressure and substrate temperature constant at 3 mtorr and $230^{\circ}C$ respectively, mainly due to an increase in carrier mobility and large grain size which would reduce the grain boundary scattering. The increase in carrier mobility with power can be attributed to the columnar growth of AZO film with (002) preferred orientation as revealed by XRD analysis. The AZO films showed a high transparency of>87% in the visible wavelength region irrespective of deposition conditions. Our results offers a cost-efficient AZO film deposition method which can fabricate films with significant low resistivity and high transmittance that can find application in thin-film solar cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.454-454
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• 2012

Magnetron sputtering에서, 영구자석의 자속은 target 표면 가까이에 전자를 구속한다. 구속된 전자는 Ar중성기체와 충돌하여 Ar이온을 발생시킬 수 있으므로, target 근처에서의 플라즈마 밀도를 높여, 자석이 없을 때보다 낮은 압력 또는 낮은 전압에서 방전할 수 있다. 구속 전자가 밀집된 공간에서 sputtering 현상이 주로 발생하기 때문에, planar target을 사용할 경우에는 target이 불균일하게 식각되어 target의 사용효율이 좋지 못하다. 이에 대한 한 가지 대안은 target을 원통형으로 만들어 회전시키는 것이다. Cylindrical target 의 내부에 위치한 영구자석은 고정시키고, target만을 회전시키면 비교적 균일하게 식각되므로 target의 사용효율을 높일 수 있다. 본 연구에서는 기존의 planar target에 대한 Particle-In-Cell Simulation을 Cylindrical target 에 적용시키기 위한 방법을 알아본다. 또한, 개발된 Simulator를 이용하여, Sputtering 조건의 변화에 대한 I-V curve의 변화를 살펴본다.

• Journal of Information Display
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• v.12 no.2
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• pp.89-92
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• 2011

Advanced static DC magnetron sputtering methods based on the magnet wobbling technique were investigated to achieve highly uniform and homogeneous metallization layers. The novel split sputter mode (SSM) method, wherein the deposition process is divided into two distinct steps, enables the AKT rotary cathode technology to provide excellent layer properties, while keeping a high production throughput. The effectiveness of theSSMtechnique was demonstrated through copper-coated large-area substrates.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.41.2-41.2
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• 2011

Display 산업의 확대로 인해 광학적 특성 및 전기적 특성이 우수한 TCO (Transparent conductive oxide) 연구가 활발히 진행되고 있다. 기존에는 ITO가 대부분의 분야에서 이용되었지만 In의 경제적인 단점으로 인해 새로운 대체물로써 ZnO가 떠오르고 있다. ZnO는 전형적인 n-type 반도체이며, wide band gap 물질로써 Al, Ga, B과 같은 3 족 원소를 doping 함으로써 광학적 및 전기적 특성을 향상시킬 수 있다. 최근에는 ZnO의 이온반경과 비슷한 Ga을 도핑한 Ga-doped ZnO 박막에 대한 연구가 활발히 진행되고 있다. 이는 ZnO에 Ga을 도핑함으로써 격자결함을 최소화 시키고 carrier concentration 및 hall mobility를 향상시켜 전기전도도의 향상을 이루기 때문이다. 본 연구에서는 $Ga_2O_3$이 3wt% doping 된 ZnO rotating cylindrical target 을 DC magnetron sputtering 을 이용하여 2 kW의 파워와 70 kHz의 주파수를 고정하고, 증착 온도를 변화시켜 유리 기판 위에 Ga-doped ZnO 박막을 증착 하였다. 증착 시 온도가 Ga-doped ZnO 박막에 미치는 영향을 관찰하기 위해 박막 표면의 조성을 분석하였고, 결정성 및 전기적 특성의 변화를 통해 박막의 특성을 비교 평가하였다. Ga-doped ZnO 박막의 표면과 두께는 SEM (Scanning electron microscope) 분석을 통해 관찰하였고, XRD (X-ray diffractometer) 를 이용하여 결정학적 특성을 확인하였다. 또한 Van der Pauw 방법을 이용한 hall 측정을 통해 resistivity, carrier concentration, hall mobility를 분석하였고, UV-Vis를 이용하여 박막의 투과율을 분석하였으며, 이를 토대로 투명 전도막으로써 Ga-doped ZnO 박막의 응용 가능성을 평가하였다.

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.85-90
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• 1997

A new ionized sputtering process was developed to fill small trench or via using additional ionizing mechanism of sputtered particles from 32cm $AlCu_x$(x=0.5%) cathode target with rotating magnet, then drawn toward substrate by small negative DC potential. The radial uniformity in RFI magnetron sputtering was studied by plasma diagnosis and appropriate RFI coil design to improve it. Optical emission intensities of excited species. $Ar^{\circ}, \;Ar^+;Al^+, \;Al^{\circ}$ are measured across the radial direction and showed close correlation with deposit's bottom to top thickness ratios in trenches and vias of submicron opening and 1.5 aspect ratio. After increase of the diameter of RF coil from 29 cm to 32 cm and improved the power leading feedthrough symmetry by removal of asymmetric single turn region, there was an increase of uniformity from 7.5% to 1.5% in bottom to top thickness ratio in 0.6 $\mu\textrm{m}$ vias.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.111-120
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• 1999

The effects of annealing in rotating magnetic field after deposition on electromagnetic properties of $Co_{82}Zr_6Mo_{12}$ thin (200~1200 $\AA$) films prepared by RF-magnetron sputtering were investigated in terms of microstructure and surface morphology. The coercivity decreases, but $4{\pi}M_5$ does not change with increasing the film thickness. The coercivity of the films was decreased below 300 $^{\circ}C$ due to stress relief and decreasing the surface roughness, while increased at 400 $^{\circ}C$ due to partial grain growth. And then, $4{\rho}M_5$ was almost independent of annealing temperatures below 200 $^{\circ}C$, but increased from 7.4 kG to 8.0 kG at 300 $^{\circ}C$ and at 400 $^{\circ}C$, which was caused by precipitation and growth of fine Co particles in the films. The electrical resistivity of films was decreased with increasing annealing temperatures and the magnetoresistance was a negative value of nearly 0 $\mu$$\Omega$cm. After annealing at 300 $^{\circ}C$, maximum effective permeability was 1200 to the hard axis of the thin films according to high frequency change. Considering the practical application of biasing layers of the films for magnetoresistive heads, optimal annealing conditions was obtained after one hour annealing at 300 $^{\circ}C$ in 400 Oe rotating magnetic field.