• Composites Research
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• v.24 no.4
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• pp.23-28
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• 2011

Recently CFRP laminate joints process by bolts and nets are developed rapidly in aircraft industries. However, there are serious drawback during jointing process. Many hole processes are needed for the manufacturing and structural applications using composite materials. Generally, very durable polycrystalline crystalline diamond (PCD) drill has been used for the CFRP hole process. However, due to the expensive price and slow process speed, chemical vapor deposition (CVD) diamond drill has been used increasingly which are relatively-low durability but easily-adjustable process speed via drill shape change and price is much lower. In this study, the comparison of hole process between PCD and CVD diamond coated drills was done. First of all, CFRP hole processbility was evaluated using the equations of hole processing conditions (feed amount per blade, feed speed). The comparison on thermal damage occurring from the CFRP specimen was also studied during drilling process. Empirical equation was made from the temperature photo profile being taken during hole process by infrared thermal camera. In addition, hole processability was compared by checking hole inside condition upon chip exhausting state for two drills. Generally, although the PCD can exhibit better hole processability, hole processing speed of CVD diamond drill exhibited faster than PCD case.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.118-122
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• 2020

Inorganic-organic hybrid perovskite solar cells have demonstrated a significant achievement by reaching a certified power conversion efficiency of 25.2% in 2019 as compared to that of 3.8% in 2009. However, organic hole conductors such as PTAA and spiro-OMeTAD are known to be expensive and unstable when they are exposed to operational conditions. In this study, the inorganic hole conductor CuSCN was used to overcome such concerns. The influence of dipropyl sulfide (DPS) and diethyl sulfide (DES) as CuSCN deposition solvents on the underlying perovskite active layer was investigated. DES solvent was observed to be advantageous in terms of CuSCN solubility and mild for the perovskite layer, thereby resulting in a power conversion efficiency of 16.9%.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.310.2-310.2
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• 2013

For enhancement of dye-sensitized solar cell performance, TiO2 blocking layer has been used to prevent recombination between electron and hole at the conducting oxide and electrolyte interface. In solid state dye-sensitized solar cells, it is necessary to fabricate pin-hole free TiO2 blocking layer. In this work, we deposited the TiO2 blocking layer on conducting oxide by atomic layer deposition and compared the efficiency. To compare the efficiency, we fabricate solid state dye-sensitized solar cell with using CuSCN as hole transport material. We see the efficiency improve with 40nm TiO2 blocking layer and the TiO2 blocking layer morphology was characterized by SEM. Also, we used this blocking layer in TiO2/Sb2S3/ CuSCN solar cell.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.660-665
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• 2020

Silicon heterojunction solar cells can achieve high conversion efficiency with a simple structure. In this study, we investigate the passivation characteristics of VOx thin films as a hole-selective contact layer using ALD (atomic layer deposition). Passivation characteristics improve with iVoc (implied open-circuit voltage) of 662 mV and minority carrier lifetime of 73.9 µs after post-deposition annealing (PDA) at 100 ℃. The improved values are mainly attributed to a decrease in carbon during the VOx thin film process after PDA. However, once it is annealed at temperatures above 250 ℃ the properties are rapidly degraded. X-ray photoelectron spectroscopy is used to analyze the chemical states of the VOx thin film. As the annealing temperature increases, it shows more formation of SiOx at the interface increases. The ratio of V5+ to V4+, which is the oxidation states of vanadium oxide thin films, are 6:4 for both as-deposition and annealing at 100 ℃, and 5:5 for annealing at 300 ℃. The lower the carbon content of the ALD VOx film and the higher the V5+ ratio, the better the passivation characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.150.1-150.1
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• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.422-429
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• 1988

The photoconductive multilayer of Se-As(hole blocking layer)/Se-As-Te (photoconductive layer) /Se-As (layer for supporiting hole transport)/Se-As(layer or controlling total capacitance)/Sb2S3(electron blocking layer) was fabricated and its electrical and optical properties were investigated. The photoconductive multilayer is made of evaporated a-Se as the base material, doped with As and Te to prevent the crystallization of a-Se and to enhance red sensitivity, respectively. The multilayer with good image reproducibility has the following deposition condition. The first layer has the thickness of 250\ulcornerat the deposition rate of 250\ulcornersec. The second layer has the thickness of 800\ulcornerat the deposition rate of 250\ulcornersec. The third layer has the thickness of 125\ulcornerat the deposition rate of 250\ulcornersec. The fourth layer has the thickness of 1700\ulcornerunder the Ar gas ambient of 50x10**-3torr. The image pick-up tube, employing this multilayer demonstrates the following characteristics. The photosensitivity is 0.8, the resolution limit is above 300TV line, and the decay lag is about 7%. And spectral response convers the whole visible range. Therfore the application to color TV camera is expected.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.46-50
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• 1995

물성을 달리한 $\alpha$-Si을 사용하여 MIM(Metal-Insulator-Metal)구조의 antifuse들을 제작하고, 물성의 변화에 따른 전기적 특성의 변화를 조사하였다. $\alpha$-Si은 PECVD (Plasma Enhanced Chemical Vapor Deposition)방법으로 증착하였으며, 물성은 RF power를 달리하여 변화시켰다. $\alpha$-Si MIM구조의 antifuse를 프로그램할 때 생기는 failure rate를 줄이기 위해 전극 사이에 삽입되는 $\alpha$-Si의 contact hole 크기와 개수를 변화시켜 보았다. MIM antifuse는 contact hole이 2개 이상일 때 failure rate가 10% 이내로 줄었으며, 프로그래밍 전류는 거의 변화가 없었다. 항복전압은 10-11V범위에 집중적으로 분포하였으며, 5V에서의 누설전류는 contact hole의 수가 증가함에 따라 커짐을 알았다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.280.2-280.2
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• 2016

The graphene, a single atomic sheet of graphite, has attracted tremendous interest owing to its novel properties including high intrinsic mobility, optical transparency and flexibility. However, for more diverse application of graphene devices, it is essential to tune its transport behavior by shifting Dirac Point (DP) of graphene. So, in the following context, we suggest a method to tune structural and electronic properties of graphene using atomic layer deposition. By atomic layer deposition of zinc oxide (ZnO) on graphene using 4-mercaptophenol as linker, we can fabricate n-doped graphene. Through ${\pi}-{\pi}$ stacking between chemically inert graphene and 4-mercaptophenol, conformal deposition of ZnO on graphene was enabled. The electron mobility of graphene TFT increased more than 3 times without considerably decreasing the hole mobility, compared to the pristine graphene. Also, it has high air stability. This ZnO doping method by atomic layer deposition can be applicable to large scale array of CVD graphene TFT.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.101-101
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• 2003

Al 박막의 화학증착(CVD)과 Al-Cu 합금박막의 물리증착(PVD)을 조합하는 CVD-PVD Al 공정은 수평방향의 배선과 수직방향의 via를 동시에 형성할 수 있으므로 공정단순화 및 생산원가절감 측면에서 장점이 있어서 DRAM 둥의 반도체 소자의 배선공정으로 매우 유망하다[1]. 본 연구에서는 CVD-PVD Al 공정을 이용하여 초고집적소자의 Al via와 Al 배선을 동시에 형성할 때 층간절연막의 영향을 조사하고 그 원인을 규명하였다. Al CVD를 위한 원료기체로는 dimethylaluminum hydride [($CH_3$)$_2$AlH]를 사용하였고 PVD는 38$0^{\circ}C$에서 실시하였다 층간절연막에 따른 CVD-PVD Al의 via hole 매립특성을 조사한 결과, high-density plasma(HDP) CVD oxide의 경우에는 via hole 매립특성이 우수하였으나, hydrogen silscsquioxane (HSQ)의 경우에는 매립특성이 우수하지 않아서 via 저항이 불균일 하였다. 이는 via 식각 후 wet cleaning 과정에서 HSQ에 흡수된 수분이 lamp를 이용한 degassing 공정에 의해서 완전히 제거되지 않아 CVD-PVD 공정 중에 탈착되어 Al reflow에 나쁜 영향을 미치기 때문으로 판단된다. CVD-PVD 공정 전에 40$0^{\circ}C$, $N_2$ 분위기에서 baking하여 HSQ 내의 수분을 충분히 제거함으로써 via 매립특성을 향상시킬 수 있었다. CVD-PVD Al 공정은 aspect ratio 10:1 이상의 via hole도 완벽하게 매립할 수 있었고 이에의해 제조된 Al 배선은 기존의 W plug 공정에 의해 제조된 배선에 비해 낮은 via 저항을 나타내었다.

• Tunnel and Underground Space
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• v.14 no.6 s.53
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• pp.429-439
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• 2004

The deep underground High Level Waste (HLW) repository to dispose of 36,000tons of spent fuel from the reactors in Korea needs about $4km^2$ repository area. In this study, the deep undergrond repository layout was optimized to minimize the excavation rock volume as well as underground repository area. In the optimization, the results from thermal analysis were used to define the influence of tunnel and deposition hole spacings on repository layout. The repository area and excavation rock volume could be reduced with longer disposal tunnel length. When it is necessary to reduce the repository area with satisfying thermal criteria, it is better to reduce tunnel spacing and increase deposition hole spacing. In contrast, the excavation rock volume can be reduced by increasing the tunnel spacing and decreasing the hole spacing.