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비대칭 마그네트론 스퍼터링 방법으로 증착한 초경도 탄화규소 박막
배경은 ( Kyung Eun Bae ),채기웅 ( Ki Woong Chae ),박종극 ( Jong Keuk Park ),이욱성 ( Wook Seong Lee ),백영준 ( Young Joon Baik ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.8
The effect of sputter target power and substrate bias voltage on the deposition of silicon carbide thin film was investigated. Films were deposited using unbalanced magnetron sputtering method with sintered silicon carbide target connected to a direct current electric power from 50 to 200 W. Ar gas was used as a sputtering gas. The distance between the target and the substrate was 7.5 cm and the deposition pressure was 3 m Torr. We used a Si single crystal wafer as a substrate, which was heated at 450℃. The substrate bias voltage was varied between 0 and -100V. Deposited films consisted of columnar grains with several nm width, which formed a texture whose orientation was influenced by the bias voltage. Most of the grains were crystalline which was confirmed by transmission electron microscopy. The hardness measured by a nano-indentation method showed a super-hardness of about 50 GPa. (Received September 17, 2014)
비대칭 마그네트론 스퍼터링 방법에 의한 탄화붕소박막의 증착거동
배경은 ( Kyung Eun Bae ),박종극 ( Jong Keuk Park ),이욱성 ( Wook Seong Lee ),배영준 ( Young Joon Baik ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.12
The effect of temperature and substrate bias on the deposition behavior of boron carbide (BC) thin film was studied. BC thin films were deposited by an unbalanced magnetron sputtering (UBM sputtering) method. The B4C target was connected to a DC power supply at 200 W and sputtered by ionized argon gas. The distance between the substrate and target was 7.5 cm and the deposition pressure was 3 mTorr with argon gas. Silicon substrates were heated by halogen lamps from room temperature to 450 ℃. DC bias voltage applied to substrates up to .100 V. The deposited films showed no diffraction peak on either X-ray diffraction and transmission electron microscopy analysis, which indicated an amorphous nature of the films irrespective of deposition temperature and substrate bias in this study. Only a 1280 cm.1 absorption peak of Fourier transform infrared spectroscopy was observed. The hardness of the BC films was about 40 GPa regardless of deposition temperature.
입방정 질화붕소 박막의 잔류응력 형성에 미치는 산소 첨가 효과
장희연(Hee-yeon Jang),박종극(Jong-Keuk Park),이욱성(Wook-Seong Lee),백영준(Young-Joon Baik),임대순(Dae-Soon Lim),정증현(Jeung-hyun Jeong) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.2
In this study, we investigated the oxygen effect on the nucleation and its residual stress during unbalanced magnetron sputtering. Up to 0.5% in oxygen flow rate, cubic phase (c-BN) was dominated with extremely small fraction of hexagonal phase (h-BN) of increasing trend with oxygen concentration, whereas hexagonal phase is dominated beyond 0.75% flow rate. Interestingly, the residual stress in cubic-phase-dominated films was substantially reduced with small amount of oxygen (~0.5%) down to a low value comparable to the h-BN case. This may be because oxygen atoms break B-N sp³ bonds and make B-O bonds more favorably, increasing sp² bonds preference, as revealed by FTIR and NEXAFS. It was confirmed by experimental facts that the threshold bias voltage for nucleation and growth of cubic phase were increased from ?55 V to ?70 V and from ?50 V to ?60 V, respectively. The reduction of residual stress in O-added c-BN films is seemingly resulting from the microstructure of the films. The oxygen tends to increase slightly the amount of h-BN phase in the grain boundary of c-BN and the soft h-BN phase of 3D network including surrounding nano grains of cubic phase may relax the residual stress of cubic phase.
권도현 ( Do Hyun Kwon ),박종극 ( Jong Keuk Park ),이욱성 ( Wook Seong Lee ),백영준 ( Young Joon Baik ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.2
The microstructure of carbon film, deposited using hot-filament chemical vapor deposition, was investigated in relation to deposition pressure and methane concentration as deposition variables. Methane concentration in hydrogen gas was varied from 0.5 to 5% in volume. Deposition pressures were 5, 15, 45 and 75 Torr. Filament temperature and deposition temperature were fixed at 2100 ℃ and 950 ℃, respectively. With increasing methane concentration, the surface morphology changed its microstructure from microcrystalline diamond, to nanocrystalline diamond, to graphite. Raman spectroscopic analysis and X-ray diffraction analysis confirmed the bonding structures corresponding to each microstructure. At 5 Torr, the surface showed a fine grained morphology, different from the microstructures in the other pressure cases; however, the bonding nature also changed from diamond to graphite with increasing methane concentration.
웨이퍼용 CVD 다이아몬드 후막의 균열발생 제어를 위한 역학적 해석
이욱성,백영준,권동일,정증현,이소윤 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.9
The mechanism of catastrophic failures in CVD-processed diamond thick films during cooling after fabrication is investigated both theoretically and experimentally in order to develop systematic methodologies for crack prevention. Finite element calculations reveal that high thermal stresses concentrate at the round edge rim of thick film and tensile thermal stress develops in the edge region. They are thought to be the cause of crack initiation and propagation, respectively. However, the cracking as a stress relaxation mechanism is competing interface decohesion between diamond film and substrate. Hence, it is suggested that the cracking occurs conditionally although thermal stress exceeding the fracture strength of film is generated in the thick film. Stress distribution should be so configured that σ_(θθ)/ σ_(zz,i) exceeds the ratio of fracture strength of film to interface adhesion strength. On the basis of the cracking condition, three methodologies were suggested to prevent the cracking; minimization of thermal hoop stress and interface adhesion strength, and the increase of film thickness. This analysis on the cracking mechanism was verified by experimental results of diamond thick film deposited on Si, Mo and W substrates. In particular, even in high thermal stress, it is ascertained experimentally that low adhesion can prevent the cracking by introducing low adhesive interlayer.
심우영,김창삼,김영도,이욱성 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.12
Tape casting process was applied to the fabrication of cemented carbide thin plate with thickness below 1 mm, which is expected to reduce the production cost and to enable the mass production of thin plates. Using the tape casting process, thin plates of cemented carbide were fabricated in the various forms such as monolithic and laminated, perforated and non-perforated thin plate forms. The debinding and sintering behavior were investigated to define the related problems and the solutions were suggested. Through sequential application of sheet forming by tape casting, lamination, debinding and vacuum sintering, the flat cemented carbide thin plates of lateral dimension, the sintered thickness and its deviation of 45-75 mm, minimum 500μm and 50μm, respectively, could be fabricated. Cemented carbide thin plates of perforated forms as well as the laminated forms could also be fabricated with a similar specification. Abnormal grain growth was observed in the microstructure, which was attributed to the incorporation of the impurities during the tape casting process. It was found to be readily preventable. Sintering behavior was investigated for the laminated composite thin plates of TiC-Ni/WC-Ni, in the performance diversification perspectives. When the grain growth kinetics were different for the two layers, an asymmetric capillary force was generated to induce a different shrinkages of the layers. This induced a severe warping of the plates. When the grain growth kinetics of the two layers were made identical by addition of grain growth inhibitor, the shrinkage difference was prevented, which enabled warp-free, dense laminated plate. (Received February 13, 2004)
금속과의 고온 반응에 의한 다결정 다이아몬드 막의 평탄화 거동
이종수,은광용,이욱성,백영준,손희식 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.2
The surface of the polycrystalline diamond film has been flattened by the reaction with thick plate or powder of Mn and Fe at 900∼1000℃ for 0.5∼20 hours in hydrogen atmosphere. The effect of the shape and kind of the metals on the flattening process has been investigated in the perspective of the macroscopic flatness and the microscopic roughness. The macroscopically flat surface could not be obtained by Mn powder and Fe powder. In contrast. treatment with thick Fe plate gave macroscopically flat surface. However, ribbon-shaped protrusions were formed on the diamond surface flattened with Fe plate. It was due to the severe grain boundary grooving on the Fe plate surface developed during the huh-temperature reaction with diamond. The protrusion could be drastically reduced by using fine-grained sintered body of Fe. This phenomenon was interpretated in terms of a simple geometrical change involving the dihedral angle of the grainboundary groove and the grain size of the Fe plate. The microscopic roughness increased in the following order: mirror polished Fe plate, Mn powder or Mn flake, mirror-polished sintered body of Fe and Fe powder.
산소-아세틸렌 토치에 의해 합성된 다이아몬드 결정 형태
은광용,이욱성,백영준 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.5
The morphology of diamond crystals grown by oxy-acetylene flame has been investigated at various radial distances in the deposition area. The main variables were deposition temperature and nozzle-to-substrate distance. It was shown that the radial variation of diamond growth shape in the deposition area was dominated by the gas species profile in the flame, rather than by the substrate temperature profile.