• Journal of Korean Vacuum Science & Technology
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• v.1 no.1
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• pp.30-37
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• 1997

Interactions of Cu films with Si substrates separated by thin layers of molybdenum and molybdenum nitride were investigated in the viewpoint of diffusion barrier to copper. the diffusion barrier behavior of the layers was studied as functions of deposition and annealing conditions by cross-sectional transmission electron microscopy and Nomarski microscopy. the layers deposited at $N_2$ gas ratios of 0.4 and 0.5 exhibited good diffusion barrier behaviors up to $700^{\circ}C$, mainly due to the phase transformation of molybdenum to $\gamma$-Mo$_2$N phase. The increase in the N gas ratio in deposition elevates the lower limit of barrier failure temperature. Futhermore, amorphous molybdenum nitride films deposited at 20$0^{\circ}C$ and 30$0^{\circ}C$ did not fail, while the crystalline $\gamma$-Mo$_2$N films deposited at 40$0^{\circ}C$ and 50$0^{\circ}C$ showed signs of interlayer interactions between Cu and Si after annealing at 75$0^{\circ}C$ for 30 minutes. Therefore, the amorphous nature of the molybdenum nitride layer enhanced its ability to reduce Cu diffusion and its stability as a diffusion barrier at elevated temperatures.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.394-394
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• 2012

We fabricated organic-inorganic superlattice films using molecular layer deposition (MLD) and atomic layer deposition (ALD). The MLD is a gas phase process in the vacuum like to atomic layer deposition (ALD) and also relies on a self-terminating surface reaction of organic precursor which results in the formation of a monolayer in each sequence. In the MLD process, 'Alucone' is very famous organic thin film fabricated using MLD. Alucone layers were grown by repeated sequential surface reactions of trimethylaluminum and ethylene glycol at substrate temperature of $80^{\circ}C$. In addition, we developed UV-assisted $Al_2O_3$ with gas diffusion barrier property better than typical $Al_2O_3$. The UV light was very effective to obtain defect-free, high quality $Al_2O_3$ thin film which is determined by water vapor transmission rate (WVTR). Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of each organic, inorganic film. Composition of the organic films was confirmed by infrared (IR) spectroscopy. Ultra-violet (UV) spectroscopy was employed to measure transparency of the organic-inorganic superlattice films. WVTR is calculated by Ca test. Organic-inorganic superlattice films using UV-assisted $Al_2O_3$ and alucone have possible use in gas diffusion barrier for OLED.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.109-110
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• 2005

We have suggested sputtered W-C-N thin film for preventing thermal budget between semiconductor and metal. These results show that the W-C-N thin film has good thermal stability and low resistivity. In this study we newly suggested sputtered W-B-C-N thin diffusion barrier. In order to improve the characteristics, we examined the impurity behaviors as a function of nitrogen gas flow ratio. This thin film is able to prevent the interdiffusion during high temperature (700 to $1000^{\circ}C$) annealing process and has low resistivity ($\sim$200$\mu{\Omega}-cm$). Through the analysis of X-Ray diffraction, resistivity and XPS, we studied structure behavior of W-B-C-N diffusion barrier.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.901-906
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• 2010

The first stage blade of a gas turbine was operated under a severe environment which included both $1300^{\circ}C$ hot gas and thermal stress. To obtain high efficiency, a thermal barrier coating (TBC) and an internal cooling system were used to increase the firing temperature. The TBC consists of multi-layer coatings of a ceramic outer layer (top coating) and a metallic inner layer (bond coat) between the ceramic and the substrate. The top and bond coating layer respectively act as a thermal barrier against hot gas and a buffer against the thermal stress caused by the difference in the thermal expansion coefficient between the ceramic and the substrate. Particularly, the bondcoating layer improves the resistance against oxidation and corrosion. An inter-diffusion layer is generated between the bond coat and the substrate due to the exposure at a high temperature and the diffusion phenomenon. A thickness measurement result showed that the bond coat of the suction side was thicker than that of the pressure side. The thickest inter-diffusion zone was noted at SS1 (Suction Side point 1). A chemical composition analysis of the bond coat showed aluminum depletion around the inter-diffusion layer. In this study, we evaluated the properties of the bond coat and the degradation of the coating layer used on a $1300^{\circ}C$-class gas turbine blade. Moreover, the operation temperature of the blade was estimated using the Arrhenius equation and this was compared with the result of a thermal analysis.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.29-35
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• 2004

We have deposited the W-N diffusion barrier on Si substrate with $NH_3$ pulse plasma enhanced atomic layer deposition (PPALD) method by using $WF_6$ and $NH_3$ gases. The $WF_6$ gas reacts with Si that the surface corrosion occurs severely, but the $NH_3$ gas incorporated with pulse plasma and $WF_6$ gas are easily deposited W-N thin film without Si surface corrosion. Because the $NH_3$ with pulse plasma can be active species dissociated and chemisorbed on Si. Thus the Si surface are covered and saturated with nitrogen, which are able to deposit the W-N thin film. We also examine the deposition mechanism and the effect of $NH_3$ pulse plasma treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.251-252
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• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.283-287
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• 2002

We have studied Zr(Si)N film as a diffusion barrier between Cu metal and Si substrate for application of interconnection metal in ULSI circuits. Zr(Si)N film was deposited with reactive DC magnetron sputtering system using $Ar/N_2$mixed gas. The value of the resistivity was the lowest for the ZrN film using 29 : 1 of Ar : $N_2$reactant gas ratio at room temperature and decreased with increasing of Si substrate temperature. As the value of ZrN film resistivity was decreased, the direction of crystal growth was toward to (002) plane. The barrier property of ZrN film added with Si was improved. But Si was added too much in ZrN film, the barrier property was degraded. The adhesive property was improved with increasing of Si in ZrN. For the analysis of the film, XRD, Optical microscopy, Scretch tester, so on were used.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.195-198
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• 2004

For a diffusion barrier against copper, tantalum nitride films have been deposited on $SiO_{2}$ by atomic layer deposition (ALD), using PEMAT(Pentakis(ethylmethylamino)tantalum) and $NH_{3}$ as precursors, Ar as purging gas. The deposition rate of TaN at substrate temperature $250^{\circ}C$ was about $0.67{\AA}$ per one cycle. The stability of TaN films as a Cu diffsion barrier was tested by thermal annealing for 30 minutes in $N_{2}$ ambient and characterized through XRD, sheet resistance, and C-V measurement(Cu($1000{\AA}$)/TaN($50{\AA}$)/$SiO_{2}$($2000{\AA}$)/Si capacitor fabricated), which prove the TaN film maintains the barrier properties Cu below $400^{\circ}C$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.439-455
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• 2020

Numerical model was developed that simulates radionuclide (3H and 14C) transport modeling at the 2nd phase facility at the Wolsong LILW Disposal Center. Four scenarios were simulated with different assumptions about the integrity of the components of the barrier system. For the design case, the multi-barrier system was shown to be effective in diverting infiltration water around the vaults containing radioactive waste. Nevertheless, the volatile radionuclide 14C migrates outside the containment system and through the unsaturated zone, driven by gas diffusion. 3H is largely contained within the vaults where it decays, with small amounts being flushed out in the liquid state. Various scenarios were examined in which the integrity of the cover barrier system or that of the concrete were compromised. In the absence of any engineered barriers, 3H is washed out to the water table within the first 20 years. The release of 14C by gas diffusion is suppressed if percolation fluxes through the facility are high after a cover failure. However, the high fluxes lead to advective transport of 14C dissolved in the liquid state. The concrete container is an effective barrier, with approximately the same effectiveness as the cover.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.273-278
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• 2016

In order to evaluate the lifespan of high-temperature parts with thermal barrier coating in gas turbines used for power generation, this study was performed on an 80 MW-class gas turbine exceeding 24 k equivalent operating hours. Degradation characteristics were evaluated by analyzing the YSZ (Yttria Stabilized Zirconia) top coat, which serves as the thermal barrier coating layer, the NiCrAlY bond coat, and interface layers. Microstructural analysis of the top, middle, and bottom sections showed that Thermal Growth Oxide (TGO) growth, Cr precipitate growth within the bond coat layer, and formation of diffusion layer occur actively in high-temperature sections. These microstructural changes were consistent with damaged areas of the thermal barrier coating layer observed at the surface of the used blade. The distribution of Cr precipitates within the bond coat layer, in addition to the thickness of TGO, is regarded as a key indicator in the evaluation of degradation characteristics.