• Composites Research
• /
• 제24권4호
• /
• pp.23-28
• /
• 2011

최근 항공용 재료 산업 분야에서 널리 사용되고 있는 CFRP의 활용이 증가되고 있다. 하지만, CFRP와 같은 복합재료 부품의 결합 시에 단점이 있다. 복합재료를 이용한 다양한 구조를 제조하기 위해선 많은 홀 가공이 필요하다. 일반적으로 CFRP 홀 가공시 내구성이 매우 강한 polycrystalline crystalline diamond (PCD) 드릴을 사용한다. 하지만, 단가가 비싸고 가공 속도가 느리기 때문에 내구성은 PCD 드릴에 비해 약하나 드릴 형상 변화를 통해 가공 속도를 조절 할 수 있고, 비교적 가격이 저렴한 chemical vapor deposition (CVD) 다이아몬드 코팅 드릴의 사용량이 증가 되고 있다. 본 연구에서는. PCD 드릴과 CVD 다이아몬드 코팅 드릴의 홀 가공성을 비교 평가하였다. 먼저, 홀 가공 조건 식 (날당 이송량, 절삭 속도)을 이용하여 CFRP 홀 가공성을 평가했으며, CFRP 가공 시 드릴링 과정에서 발생하는 시편 내부의 열적 손상 정도를 비교했다. 열화상 카메라 촬영한 홀 가공 시 발생되는 온도를 이용한 경험식을 만들어 두 드릴의 발열 정도에 따른 홀 가공성을 비교 평가하였다. 또한, 홀 가공 시 발생하는 칩(chip) 배출 여부에 따른 홀 내부의 상태를 평가하여 CVD 다이아몬드 코팅 드릴과 PCD 드릴의 CFRP 홀 가공성을 비교했다. 전반적으로 PCD 드릴의 홀 가공성이 CVD 다이아몬드 드릴에 비해 우수한 성능을 나타냈지만, 홀 생성 속도는 CVD 다이아몬드 드릴이 PCD 드릴에 비해 빠른 결과를 나타냈다.

• 한국전기전자재료학회논문지
• /
• 제17권3호
• /
• pp.299-304
• /
• 2004

In recent years, silicon carbide has emerged as an important material for MEMS application. In order to fabricate an SiC film based MEMS structure by using chemical etching method, high operating temperature is required due to high chemical stability Therefore, dry etching using plasma is the best solution. SiC film was deposited by thermal CVD at the temperature of 100$0^{\circ}C$ and pressure of 10 torr. SiC was dry etched with a reactive ion etching (RIE) system, using SF$_{6}$/O$_2$ and CF$_4$/O$_2$ gas mixture. Etch rate has been investigated as a function of oxygen concentration in the gas mixture, rf power, working pressure and gas flow rate. Etch rate was measured by surface profiler and FE-SEM. SF$_{6}$/O$_2$ gas mixture showed higher etch rate than CF$_4$/O$_2$ gas mixture. Maximum etch rate appeared at RF Power of 450W. $O_2$ dilute mixtures resulted in an increasing of etch rate up to 40％, and the superior anisotropic cross section was observe

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
• /
• pp.271-284
• /
• 1999

As a semiconductor material for electronic devices operated under extreme environmental conditions, silicon carbides (SiCs) have been intensively studied because of their excellent electrical, thermal and other physical properties. The growth characteristics of single-crystalline 4H-SiC homoepitaxial layers grown by a thermal chemical vapor deposition (CVD) were investigated. Especially, the successful growth condition of 4H-SiC homoepitaxial layers using a SiC-uncoated graphite susceptor that utilized Mo-plates was obtained. The CVD growth was performed in an RF-induction heated atmospheric pressure chamber and carried out using off-oriented substrates prepared by a modified Lely method. In order to investigate the crystallinity of grown epilayers, Nomarski optical microscopy, Raman spectroscopy, photoluminescence(PL), scanning electron microscopy (SEM) and other techniques were utilized. The best quality of 4H-SiC homoepitaxial layers was observed in conditions of growth temperature 1500$^{\circ}C$ and C/Si flow ratio 2.0 of C3H3 0.2sccm & SiH4 0.3sccm. The growth rate of epilayers was about 1.0$\mu\textrm{m}$/h in the above growth condition.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.868-871
• /
• 2003

In recent years, silicon carbide has emerged as an important material for MEMS application. In order to fabricate an SiC film based MEMS structure by using chemical etching method, high operating temperature is required due to high chemical stability. Therefore, dry etching using plasma is the best solution. SiC film was deposited by thermal CVD at the temperature of $1000^{\circ}C$ and pressure of 10 torr. SiC was dry etched with a reactive ion etching (RIE) system, using $SF_6/O_2$ and $CF_4/O_2$ gas mixture. Etch rate have been investigated as a function of oxygen concentration in the gas mixture, RF power, and working pressure. Etch rate was measured by surface profiler and FE-SEM. $SF_6/O_2$ gas mixture has been shown high etch rate than $CF_4/O_2$ gas mixture. Maximum etch rate appeared at 450W of RF power. $O_2$ dilute mixtures resulted in an increasing of etch rate up to 40%, and the superior anisotropic cross section was observed.

• 한국결정성장학회지
• /
• 제15권4호
• /
• pp.135-140
• /
• 2005

Thermal-fluid analysis was performed to understand the thermal behavior in the horizontal CVD reactor thereby to design a susceptor which has a uniform deposition rate during silicon EPI growing. Four different types of susceptor designs, standard (no hole susceptor), hole $\sharp$1 (240 mm), hole $\sharp$2 (150 mm) and hole $\sharp$3 (60 mm), were simulated by CFD (Computational Fluid Dynamics) tool. Temperature, gas flow, deposition rate and growth rate were calculated and analyzed. The degree of flatness of EPI wafer loaded on the susceptor was computed in terms of silicon growth rate. The simulation results show that the temperature and thermal distribution in the wafer are greatly dependent on inner diameter of hole susceptor and demonstrate that the introduction of hole in the susceptor can degrade wafer flatness. Maximum temperature difference appeared around holes. As the diameter of the hole decreases, flatness of the wafer becomes poor. Among the threes types of susceptors with the hole, optimal design which resulted a good uniform flatness ($5\%$) was obtained when using hole $\sharp$1.

• 반도체디스플레이기술학회지
• /
• 제10권4호
• /
• pp.119-124
• /
• 2011

Flow and temperature field in reactors are important factors for design of thermal chemical vapor deposition system to grow carbon nanotubes. In this study, effects of the variations of the inlet and outlet areas of the CVD reactor to the flow characteristics and temperature field are numerically analyzed. High temperature of the gas in the entrance region is obtained with slow gas speed resulted from the enlarged inlet area. Variation of the exit area has little effects on the flow field and temperature in the reactor. However the largest area among considered cases gives the highest gas temperature though the differences are small.

• Bulletin of the Korean Chemical Society
• /
• 제27권2호
• /
• pp.219-223
• /
• 2006

The thermal decomposition of tetrakis(ethylmethylamido) titanium (TEMAT) has been investigated in Ar and $H_2$ gas atmospheres at gas temperatures of 100-400 ${^{\circ}C}$ by using Fourier Transform infrared spectroscopy (FTIR) as a fundamental study for the chemical vapor deposition (CVD) of titanium nitride (TiN) thin film. The activation energy for the decomposition of TEMAT was estimated to be 10.92 kcal/mol and the reaction order was determined to be the first order. The decomposition behavior of TEMAT was affected by ambient gases. TEMAT was decomposed into the intermediate forms of imine (C=N) compounds in Ar and $H_2$ atmosphere, but additional nitrile (RC$\equiv$N) compound was observed only in $H_2$ atmosphere. The decomposition rate of TEMAT under $H_2$ atmosphere was slower than that in Ar atmosphere, which resulted in the extension of the regime of the surface reaction control in the CVD TiN process.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.1475-1480
• /
• 2004

Plasma Enhanced Chemical Vapor Deposition (PECVD) process uses unique property of plasma to modify surfaces and to achieve the high deposition rates. In this study, a vertical thermal RF-PECVD (Radio Frequency-PECVD) reactor is modeled to investigate thermal flow and the deposition rates with various shapes of the showerhead. The showerhead in the CVD reactor has the shape of a ring and gases are injected in parallel with the susceptor, which is a rotating disk. In order to achieve the high deposition rates, we have simulated the thermal flow fields in the reactor with several showerhead models. Especially the effects of the number of injection holes and the rotating speed of the susceptor are studied. Using a commercial code, CFDACE, which uses FVM (Finite Volume Method) and SIMPLE algorithm, governing equations have been solved for the pressure, mass-flow rates and temperature distributions in the CVD reactor. With the help of the Nusselt number and Sherwood number, the heat and mass transfers on the susceptor are investigated. In order to characteristics of measure the flatness of the layer, furthermore, the relative growth rate (RGR) is considered.

• 한국분말재료학회지
• /
• 제12권2호
• /
• pp.146-150
• /
• 2005

An optimum route to synthesize $Al_2O_3$-based composite powders with homogeneous dispersion of carbon nanotubes (CNTs) was investigated. CNTs/Metal/$Al_2O_3$ nanocomposite powders were fabricated by thermal chemical vapor deposition of $C_2H_2$ gas over metal/$Al_2O_3$ nanocomposite catalyst prepared by selective reduction of metal oxide/$Al_2O_3$ powders. The FT-Raman spectroscopy analysis revealed that the CNTs have single- and multi-walled structure. The CNTs with the diameter of 25-43 nm were homogeneously distributed in the metal/$Al_2O_3$ powders, and their characteristics were strongly affected by a kind of metal catalyst and catalyst size. The experimental results show that the composite powder with required size and dispersion of CNTs can be realized by control of synthesis condition.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.418-419
• /
• 2007

Effects of Fe catalyst film and carbon nanotube (CNT) growth temperature on the characteristics of carbon nanotube were investigated in thermal chemical vapor deposition (CVD) process. Fe catalyst was prepared by DC magnetron sputter with thickness of 5-40 nm and pre-treated with ammonia gas. CNTs were grown at $700-900^{\circ}C$. It was found that the island formation of catalyst is necessary for the CNT growth. The diameter of these CNTs shows a strong correlation with the catalyst film thickness and growth temperature.