• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.382-382
• /
• 2011

이차원 결정인 그래핀(graphene)은 전하도핑(charge doping)과 기계적 변형에 민감하기 때문에 기판의 물리 및 화학적 구조 및 특성에 따라 그래핀의 물성이 크게 영향을 받는다고 알려져 있다. 특히 널리 사용되고 있는 산화실리콘($SiO_2$/Si) 기판에 존재하는 나노미터 크기의 굴곡과 전하 트랩(charge trap)은 전하 이동도 및 화학적 안정성 등의 면에서 그래핀 고유의 뛰어난 물성을 제한하는 것으로 알려져 있다. 본 연구에서는 비정질 산화실리콘 기판을 대조군으로 삼아 편평도가 높은 결정성 h-BN (hexagonal boron nitride) 기판이 그래핀에 미치는 영향을 관찰하였다. 화학기상증착법(chemical vapor deposition 또는 CVD)으로 성장시킨 그래핀을 각 기판에 전사시킨 후 라만 분광법을 통해 전하 도핑 및 기계적 변형 정도를 측정하였다. h-BN 위에서는 외부 환경에서 기인하는 전하 도핑 정도가 산화실리콘 기판보다 적게 관찰되었다. 또한 h-BN 위에 고착된 그래핀 시료에서는 기판-그래핀 상호작용에서 기인하는 것으로 보이는 새로운 라만 분광 특성이 관찰되었다.

• Journal of the Microelectronics and Packaging Society
• /
• v.4 no.2
• /
• pp.47-54
• /
• 1997

Pt/SiO2/Si을 기판으로 사용하고 RF 마그네트론 스퍼터링에 의한 (Ba, Sr)TiO3 (BST) 씨앗층을 약 10nm 정도의 두께로 입힌 다음 그 상부에 화학 기상증착법으로 BST를 증착하여 BST seed layer가 CVD BST 박막의 특성에 미치는 영향을 조사하였다. 또한 급 속열처리가 BST 박막과 커패시터의 특성에 미치는 영향도 조사하였다. Seed layer와 급속 열처리에 의해 박막의 결정성이 향상되었으며 이로인해 유전상수가 증가되었고 주파수에 대 한 유전특성도 개선되었다. Seed layer를 도입함으로써 BST 박막과 Pt 하부전극 사이의 계 면에 존재하고 있는 산소부족\ulcorner이 사라짐을 확인할수 있었으며 이로 인해 Pt/BST/Pt 커\ulcorner 시터의 누설전류가 감소하였다. 또한 급속 열처리에 의해 BST/Pt 계면에서 트랩된 전자의 농도가 감소함으로써 누설전류 특성이 개선됨을 알수 있었다. Seed layer 위에 증착된 CVD BST 박막의 유전상수는 증착온도가 증가함에 따라 증가하였으나 누설전류도 같이 증가하 였다.

• Applied Microscopy
• /
• v.36 no.spc1
• /
• pp.25-33
• /
• 2006

Nanofabrication with finely focused ion and electron beams is reviewed, and position and size controlled fabrication of nano-metals and -semiconductors is demonstrated. A focused ion beam (FIB) interface attached to a column of 200keV transmission electron microscope (TEM) was developed. Parallel lines and dots arrays were patterned on GaAs, Si and $SiO_2$ substrates with a 25keV $Ga^+-FIB$ of 200nm beam diameter at room temperature. FIB nanofabrication to semiconductor specimens caused amorphization and Ga injection. For the electron beam induced chemical vapor deposition (EBI-CVD), we have discovered that nano-metal dots are formed depending upon the beam diameter and the exposure time when decomposable gases such as $W(CO)_6$ were introduced at the beam irradiated areas. The diameter of the dots was reduced to less than 2.0nm with the UHV-FE-TEM, while those were limited to about 15nm in diameter with the FE-SEM. Self-standing 3D nanostructures were also successfully fabricated.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.04a
• /
• pp.151-152
• /
• 2007

최근들어 Device 크기가 100nm 이하로 줄어듦에 따라 High Density Plasma Chemical Vapor Deposition(HDP-CVD) 기술로는 100nm 이하의 gap에 Aspect ratio가 6:1 이상 되는 STI(Shallow Trench Isolation) 구조를 Void 없이 채우는 것이 불가능해 지고 있다. 이를 극복하기 위하여 여러 방면으로 연구가 수행되어지고 있다. 그 방법 중의 하나인 Dep/Etch/Dep Cycle이 이번 연구에서 사용되었으며, 일반적인 HDP CVD보다 더 낮은 압력에서 증착과 식각이 수행되었다. 그 결과 다른 여러 방법들보다 좋은 막질을 얻을 수 있었으며, Gap fill 성능을 향상 시킬 수 있었다.

• Progress in Medical Physics
• /
• v.12 no.1
• /
• pp.1-8
• /
• 2001

Diamond thin films were synthesized by a chemical vapor deposition (CVD). Raman spectrum showed the diamond line at 1332 $cm^{-1}$ / and x-ray diffraction pattern exhibited a strong (111) peak of diamond. The scanning electron microscopy analysis showed that the CVD diamond thin film was grown to be unepitaxial crystallites with pyramidal hillocks. A wavelength-resolved thermoluminescence (TL) of the CVD diamond thin film irradiated with X-rays showed one peak at 430 nm around 560 K. The glow curve of the CVD diamond thin film produced one dominant 560-K peak that was caused by first-order kinetics. Its activation energy and the escape frequency were calculated to be 0.92 ～ 1.05 eV and 1.34 $\times$ 10$^{7}$ sec$^{-1}$ , respectively. The emission spectrum at 560 K was split into 1.63-eV, 2.60-eV, and 3.07-eV emission bands which is known to be attribute to silicon-vacancy center, A center, and H3 center, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.4 no.3
• /
• pp.262-275
• /
• 1994

SiC/C functionally gradient materials (FGM) were deposited on the graphite substrate by the chemical vapor deposition method. The best deposition conditions of SiC/C FGM were $1300^{\circ}C, H_2/[SiCl_4+CH_4]=10, CH_4/[$SiCl_4+CH_4]=0.5-0.6$. Despite of discontinuous input gas ratio change, the FGM of which composition was continuously changed could be obtained and continuous structural change without definite interfaces was confirmed by the SEM observation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.319-319
• /
• 2013

Even though the fabrication methods of metal oxide based thin film capacitor have been well established such as RF sputtering, Sol-gel, metal organic chemical vapor deposition (MOCVD), ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD), an applicable capacitor of printed circuit board (PCB) has not realized yet by these methods. Barium Strontium Titanate (BST) and other high-k ceramic oxides are important materials used in integrated passive devices, multi-chip modules (MCM), high-density interconnect, and chip-scale packaging. Thin film multi-layer technology is strongly demanded for having high capacitance (120 nF/$mm^2$). In this study, we suggest novel multi-layer thin film capacitor design and fabrication technology utilized by plasma assisted deposition and photolithography processes. Ba0.6Sr0.4TiO3 (BST) was used for the dielectric material since it has high dielectric constant and low dielectric loss. 5-layered BST and Pt thin films with multi-layer sandwich structures were formed on Pt/Ti/$SiO_2$/Si substrate by RF-magnetron sputtering and DC-sputtering. Pt electrodes and BST layers were patterned to reveal internal electrodes by photolithography. SiO2 passivation layer was deposited by plasma-enhanced chemical vapor deposition (PE-CVD). The passivation layer plays an important role to prevent short connection between the electrodes. It was patterned to create holes for the connection between internal electrodes and external electrodes by reactive-ion etching (RIE). External contact pads were formed by Pt electrodes. The microstructure and dielectric characteristics of the capacitors were investigated by scanning electron microscopy (SEM) and impedance analyzer, respectively. In conclusion, the 0402 sized thin film multi-layer capacitors have been demonstrated, which have capacitance of 10 nF. They are expected to be used for decoupling purpose and have been fabricated with high yield.

• Journal of the Korean Ceramic Society
• /
• v.47 no.1
• /
• pp.82-85
• /
• 2010

Recently, thin film processes for oxides and metal deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), have been widely adapted to fabricate solid oxide fuel cells (SOFCs). In this paper, we presented two research area of the use of such techniques. Gadolinium doped ceria (GDC) showed high ionic conductivity and could guarantee operation at low temperature. But the electron conductivity at low oxygen partial pressure and the weak mechanical property have been significant problems. To solve these issues, we coated GDC electrolyte with a nano scale yittria-doped stabilized zirconium (YSZ) layer via atomic layer deposition (ALD). We expected that the thin YSZ layer could have functions of electron blocking and preventing ceria from the reduction atmosphere. Yittria-doped barium zirconium (BYZ) has several orders higher proton conductivity than oxide ion conductor as YSZ and also has relatively high chemical stability. The fabrication processes of BYZ is very sophisticated, especially the synthesis of thin-film BYZ. We discussed the detailed fabrication processes of BYZ as well as the deposition of electrode. This paper discusses possible cell structure and process flow to accommodate such films.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2018.06a
• /
• pp.54-54
• /
• 2018

To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in the hot filament chemical vapor deposition (HFCVD) system. In this study the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16 and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software, ANSYS-FLUENT. To account for radiative heat-transfer in the HFCVD reactor, the discrete ordinate (DO) model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512 ~ 2802 K, and 1076 ~ 1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with experimental temperatures measured using a 2-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW.

• Korean Journal of Materials Research
• /
• v.28 no.2
• /
• pp.75-81
• /
• 2018

An ultra-high temperature ceramic, tantalum carbide, has received much attention for its favorable characteristics: a superior melting point and chemical compatibility with carbon and other carbides. One drawback is the high temperature erosion of carbon/carbon (C/C) composites. To address this drawback, we deposited TaC on C/C with silicon carbide as an intermediate layer. Prior to the TaC deposition, the $TaCl_5-C_3H_6-H_2$ system was thermodynamically analyzed with FactSage 6.2 and compared with the $TaCl_5-CH_4-H_2$ system. The results confirmed that the $TaCl_5-C_3H_6-H_2$ system had a more realistic cost and deposition efficiency than $TaCl_5-CH_4-H_2$. A dense and uniform TaC layer was successfully deposited under conditions of Ta/C = 0.5, $1200^{\circ}C$ and 100 torr. This study verified that the thermodynamic analysis is appropriate as a guide and prerequisite for carbide deposition.