• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.1313-1314
• /
• 2006

For improvement of wear resistance property of atmospheric thermal plasma sprayed molybdenum (Mo) coating, diamond deposition on the atmospheric plasma sprayed molybdenum coating by the combustion flame chemical vapor deposition (CFCVD) has been operated. In this study, to diminish the thermal damage of the substrate during operation, a thermal insulator was equipped between substrate and water-cooled substrate holder. Consequently, diamond particles could be created on the Mo coating without fracture and peeling off. From these results, it was found that this process had a high potential in order to improve wear resistance of thermal sprayed coating.

• 한국전기전자재료학회논문지
• /
• 제11권7호
• /
• pp.552-556
• /
• 1998

Diamond thin films were deposited on Si substrate using $CH_4 and H_2$mixed gas by RF plasma CVD. Prior to deposition, the substrate surface was mechanically scratched with the diamond paste of $3{\mu}m$ to improve the density of nucleation sites. The microstructure of diamond films deposited with methane(0.5%~2%) at the reaction pressure ranging from 20 torr to 50torrr were studied by a scanning electron microscope. It was observed in the deposited diamond films that the nucleation density decreased and crystallinity increased with decreasing the methane concentration. However, the nucleation density and crystallinity were decreased with decreasing the process pressure.

• 한국세라믹학회지
• /
• 제56권3호
• /
• pp.269-276
• /
• 2019

This article reports on the conditions required for the growth of crystalline boron films on silicon substrates by hot filament chemical vapor deposition method. The reactive gas was 3% diborane diluted in hydrogen. The films were characterized by optical, electronic, and atomic force microscopies; x-ray diffraction; and energy dispersive, electron energy loss, Raman, x-ray photoelectron, and Auger spectroscopies. The parameters that affect the morphologies of the films have been investigated. It was concluded that faceted crystals are produced at low B₂H₆ flows and working pressures below 200 mT. α-boron is produced between 530 and 600℃. Deposition outside this range produces thin films with a wide variety of morphologies. This result indicates that the films crystallize through a process called "abnormal or discontinuous grain growth." It is assumed that this is due to the anisotropic surfaces of boron allotropes.

• 한국진공학회지
• /
• 제18권6호
• /
• pp.481-487
• /
• 2009

탄소나노필라멘트의 직경크기를 조절하기 위하여 증착 반응초기에 $SF_6$를 증착원료기체($C_2H_2$, $H_2$)에 주입하였다. 증착 원료 기체와 $SF_6$를 열화학기상증착시스템에서 시간에 따라 싸이클릭 유량 변조시켰다. 싸이클릭 유량 변조 프로세스와 기판의 온도에 따라 기판위에 증착된 탄소나노필라멘트들의 특성을 조사하였다. 싸이클릭 에칭기간에 $SF_6$를 투입하자 탄소나노필라멘트의 직경크기는 급격히 감소하였다. 이러한 탄소나노필라멘트 직경의 크기 감소 원인은 $SF_6$ 기체의 주입에 따른 에칭능력 향상에 기인하는 것으로 이해되었다.

• 한국진공학회지
• /
• 제22권1호
• /
• pp.31-36
• /
• 2013

마이크로플라즈마 화학기상증착법(microwave plasma enhanced chemical vapor deposition, MPCVD)에 의하여 형성된 비정질 탄소 박막의 효율적인 도핑 공정을 위하여, 비정질 탄소 박막의 성장 직전 nucleated seed 상태의 기판 혹은 일부 성장된 박막 위에 비소(As) 이온을 이온 주입하였고 그 직후 다시 MPCVD에 의하여 박막을 성장시켰다. MPCVD에 의한 성장 자체가 약 $500{\sim}600^{\circ}C$ 온도에서의 어닐링 공정을 대체할 수 있으므로, 기존의 이온 주입 후 별도의 어닐링 공정과 비교 시 간략화된 공정으로도 어닐링 효과가 있다고 할 수 있다. 이온 주입 후 박막 성장으로 어닐링 효과를 얻은 비정질 탄소 박막의 경우, $2.5V/{\mu}m$의 전계에서 약 $0.1mA/cm^2$의 전계 방출 특성을 관찰할 수 있었고 또한 라만 스펙트럼 특성에서도 다이아몬드 특성 및 그래파이트 특성 모두 뚜렷이 관찰되었다. 전기적, 구조적 특성 관찰로부터 이온 주입된 As 이온이 자동 어닐링 효과에 의해 충분히 비정질 탄소 박막에 도핑되었다고 할 수 있다.

• 한국진공학회지
• /
• 제19권2호
• /
• pp.148-154
• /
• 2010

본 논문에서는 유기발광다이오드의 보호막 적용을 위하여 TCP-CVD를 이용한 실리콘 산화막 형성에서 산화막의 특성에 영향을 미치는 Power, 가스종류 및 유량, 소스와 기판거리 및 공정온도 등의 공정조건에 따른 증착된 산화막의 특성을 나타내는 증착률, 굴절률을 제어하고자 한다. 그 결과 $SiH_4$ : $O_2$ = 30 : 60 [sccm], 70 [mm]의 source와 기판 거리, Bias를 인가하지 않은 조건에서 80 [$^{\circ}C$] 이하의 공정온도를 보였으며 투과율 90% 이상, 높은 증착률 및 굴절률 1.4~1.5인 안정된 $SiO_2$ 산화박막을 제조할 수 있었다.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.23.2-23.2
• /
• 2009

Atomic layer deposition (ALD)have been proven to be a very attractive technique for the fabrication of advanced gate dielectrics and DRAM insulators due to excellent conformality and precise control of film thickness and composition, However, one major disadvantages of ALD is its relatively low deposition rate (throughput) because the deposition rate is typically limited by the time required for purging process between the introduction of precursors. In order to improve its throughput, many efforts have been made by commercial companies, for example,the modification reactor and development of precursors. However, any promising solution has not reported to date. We developed a new concept ALD system(Lucida TM S200) with high-throughput. In this process, a continuous flow of ALD precursor and purging gas are simultaneously introduced from different locations in the ALD reactor. A cyclic ALD process is carried out by moving the wafer holder up and down. Therefore, the time required for ALD reaction cycle is determined by speed of the wafer holder and vapor pressure of precursors. We will present the operating principle of our system and results of deposition.

• 한국전기전자재료학회논문지
• /
• 제17권12호
• /
• pp.1301-1307
• /
• 2004

Reduced pressure chemical vapor deposition(RPCYD) technology has been investigated for the growth of SiGe epitaxial films with two dimensional in-situ doped boron impurities. The two dimensional $\delta$-doped impurities can supply high mobility carriers into the channel of SiGe heterostructure MOSFETs(HMOS). Process parameters including substrate temperature, flow rate of dopant gas, and structure of epitaxial layers presented significant influence on the shape of two dimensional dopant distribution. Weak bonds of germanium hydrides could promote high incorporation efficiency of boron atoms on film surface. Meanwhile the negligible diffusion coefficient in SiGe prohibits the dispersion of boron atoms: that is, very sharp, well defined two-dimensional doping could be obtained within a few atomic layers. Peak concentration and full-width-at-half-maximum of boron profiles in SiGe could be achieved in the range of 10$^{18}$ -10$^{20}$ cm$^{-3}$ and below 5 nm, respectively. These experimental results suggest that the present method is particularly suitable for HMOS devices requiring a high-precision channel for superior performance in terms of operation speed and noise levels to the present conventional CMOS technology.

• Carbon letters
• /
• 제13권4호
• /
• pp.205-211
• /
• 2012

Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.

• Carbon letters
• /
• 제14권3호
• /
• pp.186-189
• /
• 2013

We report a highly sensitive $NO_2$ gas sensor based on multi-layer graphene (MLG) films synthesized by a chemical vapor deposition method on a microheater-embedded flexible substrate. The MLG could detect low-concentration $NO_2$ even at sub-ppm (<200 ppb) levels. It also exhibited a high resistance change of ~6% when it was exposed to 1 ppm $NO_2$ gas at room temperature for 1 min. The exceptionally high sensitivity could be attributed to the large number of $NO_2$ molecule adsorption sites on the MLG due to its a large surface area and various defect-sites, and to the high mobility of carriers transferred between the MLG films and the adsorbed gas molecules. Although desorption of the $NO_2$ molecules was slow, it could be enhanced by an additional annealing process using an embedded Au microheater. The outstanding mechanical flexibility of the graphene film ensures the stable sensing response of the device under extreme bending stress. Our large-scale and easily reproducible MLG films can provide a proof-of-concept for future flexible $NO_2$ gas sensor devices.