• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.139-139
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• 2011

DC magnetron sputtering과 DC pulsed magnetron sputtering을 이용하여 공정 압력별, $O_2$ 분압별, 온도등의 증착조건에 따른 IGZO 박막의 특성을 조사하였다. Working pressure 따른 deposition rate 측정한 결과 동일 파워 적용 시 DC magnetron sputtering 대비하여 DC pulsed magnetron sputtering 은 약 84% 수준에 머물렀으며, IGZO 박막 내에 $O_2$의 분압비가 증가함에 따라 투과도는 단파장 영역에서 장파장 영역으로 갈수록 상승 경향을 보였다. 캐리어 농도와 이동도 등 전기적 특성도 증가하는 경향을 보였다. 온도에 따른 전기적 특성을 비교 해 본 결과 상온과 $150^{\circ}C$ 영역에서는 유의차가 없었으며, DC pulsed magnetron sputtering의 경우 $50^{\circ}C$ 영역에서 변곡점이 형성됨을 알수 있었다.

• Journal of the Korean institute of surface engineering
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• v.49 no.5
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• pp.461-466
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• 2016

Nanocrystalline vanadium nitride (VN) coatings were deposited using asymmetric bipolar pulsed dc sputtering to further understand the influence of the pulsed plasmas on the crystal structure, microstructure and mechanical properties. Properties of VN coatings were investigated with FE-SEM, XRD and nanoindentation. The results show that, with the increasing pulse frequency and decreasing duty cycle, the coating morphology changed from a porous columnar to a dense structure, with finer grains. Asymmetric bipolar pulsed dc sputtered VN coatings showed higher hardness, elastic modulus and residual compressive stress than dc sputtered VN coatings. The results suggest that asymmetric bipolar pulsed dc sputtering technique is very beneficial for the reactive sputtering deposition of VN coatings.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.33-37
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• 2017

Single phase niobium nitride (NbN) coatings were deposited using asymmetric bipolar pulsed dc sputtering by varying pulse frequency and duty cycle of pulsed plasmas. Crystal structure, microstructure, morphology and mechanical properties were examined using XRD, FE-SEM, AFM and nanoindentation. Upon increasing pulse frequencies and decreasing duty cycles, the coating morphology was changed from a pyramidal-shaped columnar structure to a round-shaped dense structure with finer grains. Asymmetric bipolar pulsed dc sputtered NbN coatings deposited at pulse frequency of 25 kHz is characterized by higher hardness up to 17.4 GPa, elastic modulus up to 193.9 GPa, residual compressive stress and a smaller grain size down to 27.5 nm compared with dc sputtered NbN coatings at pulse frequency of 0 kHz. The results suggest that the asymmetric bipolar pulsed dc sputtering technique is very beneficial to reactive deposition of transition-metal nitrides such as NbN coatings.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.179-184
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• 2011

This work investigated the effect of duty cycle and pulse frequency on the microstructures and properties of titanium nitride thin films deposited by asymmetric bipolar pulsed DC sputtering system. Oscilloscope traces of the I-V waveforms indicate high power and high current density outputs during the asymmetric bipolar pulsed mode. The grain size decreases with decreasing duty cycle. The duty cycle has a strong influence not only on the microstructural properties but also on the mechanical properties of titanium nitride films. Comparing with the continuous DC sputtering, the titanium nitride films prepared by pulsed DC asymmetric bipolar process exhibit better properties.

• Journal of the Korean institute of surface engineering
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• v.47 no.2
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• pp.86-92
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• 2014

The purpose of this comparative study was to investigate the properties of chromium nitride coatings deposited by asymmetric bipolar pulsed DC sputtering and DC sputtering system. Oscilloscope traces of the I-V waveforms indicate high power and high current density outputs during the asymmetric bipolar pulsed mode. The grain size decreases with decreasing duty cycle. The duty cycle has a strong influence not only on the microstructural properties but also on the mechanical properties of chromium nitride coatings. Comparing with the continuous DC sputtering, the chromium nitride coatings prepared by pulsed DC asymmetric bipolar process also exhibit better surface roughness.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.59.2-59.2
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• 2015

Modification of film structure and properties in inductively-coupled plasma (ICP) assisted dc and pulsed dc sputtering has been reported by Oya and Kusano [1] and by Sakamoto, Kusano, and Matsuda [2], showing drastic changes in films structure and properties by the ICP assistance in particular to the pulsed dc discharge. Although mechanisms involved in the modification has been reported to be the increase in energy transferred to the substrate, details of effects of low-energy ion bombardment on the modification and origin of an anomalous increase in the ion quantity by the ICP assistance to the pulsed dc discharge have not been discussed. In this presentation, mechanisms involved in film structure and property modification in ICP assisted dc and pulsed dc sputtering, in which a number of low-energy ions are formed, will be discussed based on ion energy distribution as well as effectiveness of energy transfer to the substrate by low energy particles [3]. The results discussed in this presentation will emphasize the fact that the energetic particles playing an important role in the film structure modification are those to be deposited, but not those of inert gas, when their energies range in less than 100 eV in the pressure range of magnetron sputtering.

• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.168-173
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• 2014

The paper presents the comparative results of TiAlN coatings deposited by DC and pulsed DC asymmetric bipolar magnetron sputtering systems. The results show that, with the decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar to a dense structure, with finer grains. Pulsed sputtered TiAlN coatings showed higher hardness, higher residual stress, and smaller grain sizes than dc prepared TiAlN coatings. Moreover residual stress of pulsed sputtered TiAlN coatings increased on increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.136-141
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• 2015

The paper presents the comparative results of NbN coatings deposited by DC and pulsed DC asymmetric bipolar magnetron sputtering systems. The results show that, with the decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar to a dense structure, with finer grains. The Pulsed sputtered NbN coatings showed higher hardness, higher residual stress, and smaller grain sizes than those of DC prepared NbN coatings. Moreover residual stress of pulsed sputtered NbN coatings increased on increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.44-48
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• 2013

Niobium oxide($Nb_2O_5$) films were deposited on p-type Si wafers at room temperature using in-line pulsed-DC magnetron sputtering system with various frequencies. The different duty ratios were obtained by varying the frequency of pulsed DC power from 100 to 300 kHz at the fixed reverse time of $1.5{\mu}s$. From the thickness of the sputtered $NbO_x$ films, it was possible to obtain much higher deposition rate in case of pulsed-DC sputtering than RF sputtering. However, the similar leakage currents and structural characteristics were obtained from the metal-insulator-semiconductor(MIS) structure fabricated with the $NbO_x$ films and the x-ray photoelectron spectroscopy(XPS) results in spite of the different deposition rates. From the experimental results, the $NbO_x$ films sputtered by pulsed-DC sputtering are expected to be used in the fabrication process instead of RF sputtering.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.390-395
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• 2013

Nanocrystalline CrN films were deposited on Si (100) substrates by means of asymmetric pulsed DC reactive magnetron sputtering. We investigated the growth behavior, corrosion resistance and mechanical properties of CrN films with a change in the duty cycle and pulse frequency. The grain size of the CrN films decreased from 25.4 nm to 11.2 nm upon a decrease in the duty cycle. The corrosion potentials for the CrN films by DC sputtering was approximately - 0.6 V, and it increased to - 0.3 V in the CrN films which underwent pulsed sputtering. The nanoindentation hardness of the CrN films also increased with a decrease in the duty cycle. This enhancement of the corrosion resistance and mechanical properties of pulsed sputtered CrN films could be attributed to the densification and surface smoothness of the microstructure of the films.