• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.28-30
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• 1992

Long incubation period of W nucleation on the TiN glue layer is a serious problem in blanket W process. In this study we investigated the dependence of W nucleation and growth rate on the preparation method of the TiN film, deposition temperature, chemistry, $SiH_4/WF_6$ ratio and sputter etching, ion implantation, and $SiH_4$ flushing pre-treatments. Incubation periods of W nucleation and deposition rates of W growth on three different TiNs are in the order of TiN>RTP-TiN> annealed TiN and TiN${\leq}$RTP-TiN${\leq}$ annealed TiN, respectively. $\beta$-W is not found on TiN substrate even for high $SiH_4/WF_6$ ratio. Sputter etching pre-treatment increases incubation period of W nucleation, while it decreases deposition rate. $SiH_4$ flushing pre-treatment decreases incubation period, but it slightly decreases deposition rate.

• Applied Microscopy
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• v.24 no.3
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• pp.78-86
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• 1994

A TEM study on proeutectoid ${\alpha}$ reaction at sub-eutectoid temperatures has been made in hypoeutectoid Ti-3.gw/o Co and Ti-5.2w/o Fe alloys. Widmanstatten ${\alpha}$ plates were formed in both alloys within the ${\beta}$ matrix with some modification of degenerate forms. These degenerate plates were formed by the sympathetic nucleation of ${\alpha}$ plates at ${\alpha}:{\beta}$ interphase boundaries. Three types of sympathetic nucleation, i.e., edge-to-edge, face-to-edge, face-to-face, were found in both alloys. The edge-to-edge sympathetically nucleated crystals formed a low-angle boundary between two crystals. The ${\alpha}:{\beta}$ interphase boundaries were found to be partially coherent interfaces which consist of regularly spaced misfit dislocations. The growth of these interphase boundaries were accomplished by the lateral movement of growth ledges. The intersection points of two ${\alpha}$ plates or the low angle boundaries which had formed by edge-to-edge sympathetic nucleation played a role as the potential sources of growth ledges during the growth of plate. The interfacial structures and the spatial morphologies of the degenerate proeutectoid ${\alpha}$ plates would be expected to influence the nucleation and growth of the succeeding eutectoid decomposition process.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1464-1469
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• 2004

In this study, micro square heaters having dimensions of $65{\times}65{\mu}m^2$and $100{\times}100{\mu}m^2$ were fabricated and bubble nucleation experiments on the heaters were performed. Bubble nucleation temperature was also measured using a bridge circuit and the photographs of bubble nucleation and subsequent growth were taken by a camera with a flash unit. Measured bubble nucleation temperatures were found to be closer to the superheat limit of working fluid (FC-72). Also quasi-1D analyses for the square heaters were performed. The quasi-1D analysis yielded proper temperature distribution of the square heater at steady state, however failed to predict the temperature rise up to the steady state. Similar time dependent temperature can be obtained with proper value of thermal diffusivity. For the $100{\times}100{\mu}m^2$ square heater, nucleation of several bubbles was observed while only one bubble was observed to be nucleated on $65{\times}65{\mu}m^2$ heater.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1541-1546
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• 2012

The early stages of bismuth (Bi) electrodeposition on glass carbon electrode from alkaline electrolyte were studied by cyclic voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy and X-ray diffraction. The CV analysis showed that the electrodeposition of Bi was determined to be quasireversible process with diffusion controlled. The current transients for Bi electrodeposition were analyzed according to the Scharifker-Hills model and the Heerman-Tarallo model. It can be concluded that the nucleation and growth mechanism was carried out under a 3D instantaneous nucleation, which was confirmed by SEM analysis. The kinetic growth parameters were obtained through a nonlinear fitting. In addition, the Bi film obtaining at -0.86 V for 1 hour was of compact and uniform surface with good smoothness, small roughness and a very high purity. The Bi film were indexed to rhombohedral crystal structure with preferred orientation of (0 1 2) planes to growth.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.40-54
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• 1999

The flame structure and soot formation in the counterflow Ethylene-Air nonpremixed flame are numerically analyzed. The present soot reaction mechanism involves nucleation, surface growth, particle coagulation, and oxidation steps. The gas phase chemistry and the soot nucleation, surface growth reactions are coupled by assuming that the nucleation and soot mass growth has the certain relationship with the concentration of benzene and acetylene. In terms of the centerline velocity and the soot volume fraction, the predicted results are compared with the experimental data. The detailed discussion has been made for the sensitivity of model constants and the deficiencies of the present model. Numerical results indicated that the acetylene addition to the soot surface plays the dominant role in the soot mass growth for the counterflow nonpremixed flame.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.246-246
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• 2010

As the trench width in the interconnect technology decreases down to nano-scale below 50 nm, superconformal gap-filling process of Cu becomes very critical for Cu interconnect. Obtaining superconfomral gap-filling of Cu in the nano-scale trench or via hole using MOCVD is essential to control nucleation and growth of Cu. Therefore, nucleation of Cu must be suppressed near the entrance surface of the trench while Cu layer nucleates and grows at the bottom of the trench. In this study, suppression of Cu nucleation was achieved by treating the Ru barrier metal surface with capacitively coupled hydrogen plasma. Effect of hydrogen plasma pretreatment on Cu nucleation was investigated during MOCVD on atomic-layer deposited (ALD)-Ru barrier surface. It was found that the nucleation and growth of Cu was affected by hydrogen plasma treatment condition. In particular, as the plasma pretreatment time and electrode power increased, Cu nucleation was inhibited. Experimental data suggests that hydrogen atoms from the plasma was implanted onto the Ru surface, which resulted in suppression of Cu nucleation owing to prevention of adsorption of Cu precursor molecules. Due to the hydrogen plasma treatment of the trench on Ru barrier surface, the suppression of Cu nucleation near the entrance of the trenches was achieved and then led to the superconformal gap filling of the nano-scale trenches. In the case for without hydrogen plasma treatments, however, over-grown Cu covered the whole entrance of nano-scale trenches. Detailed mechanism of nucleation suppression and resulting in nano-scale superconformal gap-filling of Cu will be discussed in detail.

• Fibers and Polymers
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• v.4 no.3
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• pp.102-106
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• 2003

Crystallization behaviour of blends of different MFI isotactic polypropylenes (PP), and blends of PP with carbon nanofibre have been investigated by DSC and polarizing optical microscope. Both higher MFI PP component and the carbon nanofibre in the blend influence the nucleation activity of the melt during non-isothermal crystallization. In presence of carbon nanofibre, the sherulitic growth rate is highly disturbed. The calculation of nucleation activity indicates that carbon nanofibres act as active substrate for heterogeneous nucleation.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.237-248
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• 2005

Results from in-situ high temperature X-ray diffraction measurements show that $Mg_{2}SiO_{4}{-}$spinel converts back to olivine phase only when heated in vacuum, and that at some high temperature, the olivine phase grows with time at the expense of the spinel phase strongly suggesting a 'nucleation and growth' type transition. In order to obtain the activation energy of spinel-olivine back transformation, kinetics measurements were performed on $Mg_{2}SiO_{4}{-}$spinel in vacuum at high temperatures between 1023 and 1116 K. Activation energy was determined using 'time to a given fraction method'. By employing the Avrami equation, it was found that n values generally increase with increasing temperature in a wide range implying that the nucleation and growth mechanism is probably temperature-dependent. It is likely that in spinel, at a relatively lower transformation temperature, after nucleation sites saturated, the growth of the new phase starts on the surface and gradually moves inwards. At high temperatures, however, after nucleation sites saturated, the growth starts both on the surface as well as at the interior.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.66-73
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• 1991

During the growth of macroscopically dislocation-free Czochralski silicon crystal, micro precipitates causing stacking faults in the silicon wafer during the oxidation are formed Thermal history the cryscausing acquire during the growth process is known to be a key factor determining the nucleation of this micro precipitates. In this article, various mechanisms suggested on the formation of microdefects in the silicon crystal are reviewed to secure the nucleation mechanism of the micro precipitates causing OSF whose pattern is normally ring or annular in CZ silicon crytal. B-defects which are known as vacancy clustering are considered to be the heterogeneous nucleation sites for the micro precipitates causing OSF in the CZ silicon crystals.

• Transactions of Materials Processing
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• v.22 no.8
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• pp.450-455
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• 2013

In the current study, a new dynamic recrystallization model for predicting high temperature flow stress is developed based on a physical model and the mean field theory. In the model, the grain aggregate is assumed as a representative volume element to describe dynamic recrystallization. The flow stress and microstructure during dynamic recrystallization were calculated using three sub-models for work hardening, for nucleation and for growth. In the case of work hardening, a single parameter dislocation density model was used to calculate change of dislocation density and stress in the grains. For modeling nucleation, the nucleation criterion developed was based on the grain boundary bulge mechanism and a constant nucleation rate was assumed. Conventional rate theory was used for describing growth. The flow stress behavior of pure copper was investigated using the model and compared with experimental findings. Simulated results by cellular automata were used for validating the model.