• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.169-169
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• 2000

최근 반도체 소자의 초고집적화 현상에 따라 기존의 Al-base 합금에 대한 한계에 달하면서 그에 대한 대체 물질로 Cu가 관심을 모으게 되었고 그럼으로써 Cu metallization을 위한 많은 연구가 진행되어 왔다. Cu는 Al-base 합금계보다 비저항이 낮고, 녹는점이 높으며, 또한 electromigration 특성이 뛰어난 것으로 알려져 있다. 공학적인 면에서 이미 이들 계에 대한 adhesion 및 전기적 특성에 대한 많은 연구가 있어왔지만, 이들 특성 변화에 대한 물리적 의미를 제공할 만한 기초 자료들이 부족한 상태이다. 본 연구에서는 부도체인 polyimide 박막과 diffusion barrier인 TiN 박막위에서의 Cu 박막성장에 따르는 interface chemical reaction의 변화를 XPS를 이용하여 관찰함으로서 이들 계에 있어서의 adhesion과의 관계를 조사하였다. 그리고 XPS를 이용한 modified surface accumulation method를 적용시켜 TiN diffusion barrier를 통한 Cu의 grain boundary diffusion 상수들을 측정하였다. Cu/TiN system의 경우에는 interface chemical reaction이 일어나지 않았지만 Cu/polymide system에 있어서는 boundary diffusivity는 특히 40$0^{\circ}C$에서 $650^{\circ}C$ 영역에서, Db=60$\times$10-11exp[-0.29/(kBT)]cm2/sec 이었다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.3
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• pp.193-204
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• 2012

This paper is comparing numerical schemes for a differential equation with convection and fourth-order diffusion. Our model equation is $h_t+(h^2-h^3)_x=-(h^3h_{xxx})_x$, which arises in the context of thin film flow driven the competing effects of an induced surface tension gradient and gravity. These films arise in thin coating flows and are of great technical and scientific interest. Here we focus on the several numerical methods to apply the model equation and the comparison and analysis of the numerical results. The convection terms are treated with well known WENO methods and the diffusion term is treated implicitly. The diffusion and convection schemes are combined using a fractional step-splitting method.

• Applied Microscopy
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• v.52
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• pp.8.1-8.7
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• 2022

The Korean trident goby, Tridentiger brevispinis, lives in adverse habitats that can easily become hypoxic due to low precipitation, regional dry periods, and high amounts of solar radiation. Histological and morphometric studies revealed the goby's specialized skin (35.4-150.0㎛ in thickness), consisting of an epidermis and dermis. The thicker epidermis comprises an outermost surface layer (having taste buds, stratified fattened cells, mucous cells, pigment cells, and stratified polygonal cells), middle layer (having stratified polygonal cells), and stratum germinativum (stratified columnar cells). In particular, the dermis has scales, well-developed vascularization, and a few blood capillaries just above the basement membrane, and a reduced diffusion distance was present in the lateral body. Consequently, adaptations such as thicker epidermis, well-developed vascularization, few blood capillaries, and a reduced diffusion distance may provide cutaneous respiration for survival in poorly oxygenated water during the periodic dry season.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.118.1-118.1
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• 2016

The laser surface modification has been reported for its functional applications for improving tribological performance, wear resistance, hardness, and corrosion property. In most of these applications, continuous wave lasers and pulsed lasers were used for surface melting, cladding, alloying. Since flexibility in processing, refinement of microstructure and controlling the surface properties, technology utilizing lasers has been used in a number of fields. Especially, femtosecond laser has great benefits compared with other lasers because its pulsed width is much shorter than characteristic time of thermal diffusion, which leads to diminish heat affected zone. Moreover, laser surface engineering has been highlighted as an effective tool for micro/nano structuring of materials in the bio application field. In this study, we applied femtosecond and nanosecond pulsed laser to treat biometals, such as Mg, Mg alloy, and NiTi alloy, by heating to improve corrosion properties and functionalize their surface controlling cell response as implantable biomedical devices.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.536-543
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• 1984

Thermal structure of two-dimensional surface discharge of the heated water into a rectangular resesvoir is investigated by a laboratory simulation with a shallow open channel and a relatively large reservoir. Experimental study is focused on the nature of interfacial mixing between a flowing layer of the hot water and the underlying cold water. For various conditions, mean temperature field, surface velocity distribution and turbulent mixing process have been quantitatively observed. It is found that the Richardson number strongly affects the integral structure of the flow field, and the buoyancy plays a role to control the turbulent diffusion process.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.538-543
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• 1999

The theory of the reflow applied to metallization process was studied, and the factors affecting the reflow and the relation between the reflow and the grain growth were investigated. The driving force for the metal reflow is the difference in chemical potentials along the metal surface, and it causes the atom movement. On condition that metal interconnect is fabricated for semiconductor devices, surface diffusion is the primary atom movement mechanism. The metal reflow is influenced by reflow temperature, reflow time, reflow ambient, thin film thickness, thin film material, underlayer material, pattern size, and aspect ratio. It is supposed that the reflow characteristic varies according to the grain growth during the reflow, so the effect of the grain growth on the reflow should be considered.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.175-176
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• 2000

Electric fields and the wall voltages in a surface-type AC PDP cell were measured using a Laser Induced Fluorescence Spectroscopy. For the condition of He 100Torr, 200V sustain voltage and 50kHz sustain frequency, the wall voltage dropped from about 50V to about -75V within $1{\mu}sec$ after the main discharge. And the wall voltage decreased with the rate of $10.8V/{\mu}sec$ due to the accumulation of the space charges after $1{\mu}sec$. But when the operating pressure was 40Torr, it increased with the rate of $4.5V/{\mu}sec$ because the diffusion effect of the wall charge on MgO surface was more dominant than the accumulation effect of the space charges. During the pulse-off period, the wall voltage decreased slightly due to the diffusion of the wall charge. When the sustain voltage was 250V, the self-erasing discharge occurred, and the absolute value of the wall voltage decreased rapidly just after the pulses were off, which was caused by the accumulation of the charges generated by the self-erasing discharge.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.225-230
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• 2002

Sn was selected as an alloying element of Cu. The Cu-Sn thin layers were deposited on the Si substrates by the electroplating method and their properties were studied. By rapidly thermal annealing(RTA) up to 40$0^{\circ}C$ after electroplating, sheet resistance decreased and adhesion strength increased, but that trend was reversed at the 50$0^{\circ}C$ RTA. Cu-Sn particles grew dense and the surface was uniform up to 40$0^{\circ}C$, but at 50$0^{\circ}C$, empty area was introduced and the surface became rough owing to oxidation and particle coarsening and agglomeration. Deposited layer contained significant amount of Si, while pure Cu-Sn layer with the composition ratio of 90:10 was present only on the top surface. However, no significant change in the Cu composition within alloy layers occured by the RTA regardless of its temperature. This indicates that the Cu diffusion into the Si was suppressed by the presence of Sn.

• Journal of the Korean institute of surface engineering
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• v.45 no.2
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• pp.61-69
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• 2012

Alloys of Fe-(5, 10, 15)Al and Fe-(10, 20, 30, 40)Cr were corroded at 700 and $800^{\circ}C$ for 70 hr in either atmospheric air or 1 atm of Ar+$1%SO_2$ gases. In these atmospheres, Fe-5Al and Fe-10Cr alloys displayed poor corrosion resistance. In atmospheric air, Fe-5Al alloys formed oxide nodules, while Fe-10Cr alloys formed thick scales and internal oxides. In Ar+$1%SO_2$ gases, Fe-5Al and Fe-10Cr alloys formed thick, nonadherent bi-layered scales, which grew primarily by the outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions. By contrast, in atmospheric air and Ar+$1%SO_2$ gases, Fe-(10, 15)Al and Fe-(20, 30, 40)Cr alloys displayed good corrosion resistance by forming $Al_2O_3$ and $Cr_2O_3$ layers on the surface, respectively.

• Journal of the Korean institute of surface engineering
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• v.46 no.5
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• pp.192-196
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• 2013

Stainless steels (AISI 316L) are carburized by Inductively coupled plasma using $CH_4$ and Ar gas. The ${\gamma}_c$ phase(S-phase) is formed on the surface of stainless steel after carburizing process. The XRD peak of carburized samples is shifted to lower diffracting angle due to lattice expansion. Overall, the thickness of ${\gamma}_c$ phase showed a linear dependence with respect to increasing temperature due to the faster rate of diffusion of carbon. However, at temperatures above 500, the thickness data deviated from the linear trend. It is expected that the deviation was caused from atomic diffusion as well as other reactions that occurred at high temperatures. The interfacial contact resistance (ICR) and corrosion resistance are measured in a simulated proton exchange membrane fuel cell (PEMFC) environment. The ICR value of the carburized samples decreased from 130 $m{\Omega}cm^2$ (AISI 316L) to about 20 $m{\Omega}cm^2$. The sample carburized at 200 showed the best corrosion current density (6 ${\mu}Acm^{-2}$).