• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.172-172
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• 2011

현대 반도체 금속배선 연구에서는 기존에 쓰이던 Al (Aluminium) 금속배선 대신에 Cu(Copper) 금속배선 연구가 진행 되고 있다. Cu는 Al 보다 비저항이 낮고, 녹는점도 Al보다 높다는 장점이 있지만 저온에서 기판인 Si (Silicon) 과 반응하고 접착력이 우수하지 못 하다는 단점이 있다. 이런 문제를 해결하기 위하여 확산방지막을 기판과 금속배선 사이에 삽입하는 방법이 제시 되었다. 확산방지막으로는 기존에 쓰이던 Ti (Titanium) 계열의 확산방지막과 W (Tungsten) 계열의 확산방지막이 있다. 이번 연구에서는 W 계열의 확산방지막에 불순물 C (Carbon), N(Nitrogen)을 첨가한 W-C-N 확산방지막 시편을 제조하였고, N2의 비율을 변화시키며 $600^{\circ}C$ 열처리를 하였다. 실험 결과 질소의 포함 농도에 따라 확산방지막의 안정도가 변화한다는 결과를 얻었으며, 질소 첨가량에 따라 시편의 표면 보다는 시편의 중간층의 물성 변화율이 큰데 이는 시편 표면의 질소는 열처리 중 확산에 의한 시편과의 분리 현상이 일어나지만 시편의 중간층은 trap현상에 의하여 시편에 남아있어 질소의 영향을 받아 시편의 중간층이 더욱 질소 유량에 따른 영향이 큰 것을 확인하였다. 이 결과로부터 W-C-N 박막은 첨가된 질소의 유량에 따라 박막의 안정도가 결정된 다는 것을 알았다. 본 연구에서 시편은 rf magnetron sputtering 방법으로 제작하였고 연속압입 실험은 Hysitron사의 Triboindenter를 이용하였다. Indenting에 사용된 압입팁은 Berkovich tip을 사용하였다.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.30-36
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• 2006

A novel method was proposed to grow an epitaxial $CoSi_2$ on (100)Si substrate. A $CoN_x$ interlayer was deposited by reactive sputtering of Co in an Ar+$N_2$ flow. From the Ti/Co/$CoN_x$/Si structure, a uniform and thin $CoSi_2$ layer was epitaxially grown on (100)Si by annealing above $700^{\circ}C$. Two amorphous layers were found at the $CoN_x$/Si interface, where the top layer has a silicon nitride (Si-N) bonding state with some Co content and the bottom layer has a Co-Si intermixing state. The SiNx amorphous layer seems to play a critical role of suppressing the diffusion of Co into Si substrate for the direct formation of epitaxial $CoSi_2$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.98-102
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• 2000

Ferroelectric PZT heterolayered thin films were fabricated by spin coating method on the Pt/Ti/SiO2/Si substrate using PZT(10/90) and PZT(90/10) m7etal alkoxide solutions. All PZT heterolayered films showed a homogeneous grain structures without presence of rosette structure. It can be assumed that the lower PZT layers played a role of nucleation site for the formation of the upper PZT layer. Pb-deficient PZT phase was formed at PZT/Pt interface due to the diffusion of Pb element into a Pt bottom electrode. The relative dielectric constant and the dielectric loss of the PZT-6 film were 567 and 3.6%, respectively. Increasing the number of coatings, remanent polarization and coercive field were decreased and the values of the PZT-6 heterolayered film were $7.18\muC/cm^2$ and 68.5kV/cm, respectively. Leakage current densities were increased with increasing the number of coatings, and the value of the PZT-4 film was about $7\times10-8A/cm^2$ at 0.05MV/cm.

• Corrosion Science and Technology
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• v.2 no.3
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• pp.109-116
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• 2003

It is well known that SSCC (sulfide stress corrosion cracking) is caused by drastic ingression of hydrogen during the service and accumulation of hydrogen near the potential crack initiation site in the material. It is important to characterize the hydrogen trapping behavior to evaluate the service performance of the high strength pipeline steels. In this study. the relationship between the hydrogen trapping behavior and SSCC susceptibility is evaluated in terms of alloy composition, microstructure and carbide behavior. The hydrogen trapping behavior was measured by electrochemical hydrogen permeation test cell (Devanathan cell). The SSCC susceptibility is evaluated by constant extension rate test and constant strain lest method. The hydrogen trapping behavior is affected greatly by microstructure and nature of carbide particles. The fine TiC, and NbC in the matrix of ferritic structure acts as strong irreversible trap sites whereas the bainitic structure acts as reversible trap site. The SSCC susceptibility is closely related to not only the hydrogen trapping behavior but also the loading condition. As the activity of reversible trap site increases, SSCC susceptibility decreases under static loading condition below yield strength, whereas SSCC susceptibility increases under dynamic loading condition or above yield strength. As the activity of irreversible trap site increases. SSCC susceptibility increases regardless of loading condition. It is cased by the mixed effect of dislocation on hydrogen diffusion and trapping behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.162-172
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• 2008

We studied the effect of an Al underlayer on the growth of carbon nanotubes (CNTs) and their field emission characteristics, First of all, CNTs were grown on the Invar catalyst layers with different thickness of 1 to 10 nm, showing that the CNT length was saturated for the catalyst 5 nm or thicker. The CNTs grown on the 5-nm-thick catalyst were ${\sim}10{\mu}m$ long and ${\sim}30nm$ in diameter. Second, an Al underlayer was applied between the catalyst layer and the Ti diffusion barrier to reduce the diameters of CNTs for better field emission properties by forming spherical Al oxide particles on which smaller catalyst nanoparticles would occur. The optimal thickness of an Al underlayer underneath the 5-nm-thick catalyst was ${\sim}15nm$, producing the CNTs with the length of ${\sim}15{\mu}m$ and the diameter of ${\sim}15nm$. The field emission measurements, following the tape activation, showed that the thinner and longer CNTs gave rise to better field emission performance with the lower turn-on and threshold electric fields.

• Membrane and Water Treatment
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• v.2 no.4
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• pp.239-250
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• 2011

A photovoltaic powered ultrafiltration and reverse osmosis system was tested with a number of natural groundwaters in Australia. The objective of this study was to compare system performance at six remote field locations by assessing the impact of water composition and fluctuating energy on inorganic contaminant removal using a BW30-4040 membrane. Solar irradiance directly affected pressure and flow. Groundwater characteristics (including TDS, salts, heavy metals, and pH), impacted other performance parameters such as retention, specific energy consumption and flux. During continual system operation, retention of ions such as $Ca^{2+}$ and $Mg^{2+}$ was high (> 95%) with each groundwater which can be attributed to steric exclusion. The retention of smaller ions such as $NO_3{^-}$ was affected by weather conditions and groundwater composition, as convection/diffusion dominate retention. When solar irradiance was insufficient or fluctuations too great for system operation, performance deteriorated and retention dropped significantly (< 30% at Ti Tree). Groundwater pH affected flux and retention of smaller ions ($NO_3{^-}$ and $F^-$) because charge repulsion increases with pH. The results highlight variations in system performance (ion retention, flux, specific energy consumption) with real solar irradiance, groundwater composition, and pH conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.100-100
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• 2000

Aluminium oxide (Al2O3) films have been investigated for many applications such as insulating materials, hard coatings, and diffusion barriers due to their attractive electrical and mechanical properties. In recent years, application of Al2O3 films for dielectric materials in integrated circuits as gates and capacitors has attracted much attention. Various deposition techniques such as sol-gel, metalorganic decomposition (MOD), sputtering, evaporation, metalorganic chemical vapor deposition (MOCVD), and pulsed laser ablation have been used to fabricate Al2O3 thin films. Among these techniques, reactive sputtering has been widely used due to its high deposition rate and easy control of film composition. It has been also reported that the sputtered Al2O3 films exhibit superior chemical stability and mechanical strength compared to the films fabricated by other processes. In this study, Al2O3 thin films were deposited on Pt/Ti/SiO/Si2 and Si substrates by DC reactive sputtering at room temperature with variation of the Ar/O2 ratio in sputtering ambient. Crystalline phase of the reactively sputtered films was characterized using X-ray diffractometry and the surface morphology of the films was observed with Scanning election microscopy. Effects of Th Ar/O2 ratio characteristics of Al2O3 films were investigated with emphasis on the thickness dependence of the dielectric properties. Correlation between the dielectric properties and the microstructure was also studied

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.73-73
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• 2001

Boron-containing materials have several excellent properties, such as superlnardness, insulation and non-Rinear optical property. Recently, oxynitride compounds, such as Si(ON), Ti(ON), became the promising materials applied in diffusion barrier layer and solar cell. With the expectation of obtaining the hybrid property, we have firstly grown the BON thin film by radio frequency (R.F.) plasma enhanced metalorganic chemical vapm deposition (PEMOCVD) with 100 kHz frequency and trimethyl borate precursor. The plasma source gases used in this study were Ar and $H_2$, and two kinds of nhmgen source gases, $N_2$ and <$NH_3$, were also employed. The as-grown films were characterized by XPS, IR, SEM and Knoop microlhardness tester. The relationship between the films hardness and the growth rate indicated that the hardness of the film was dependent on several factors such as nitrogen source gas, substrate temperature and film thickness due to the variation of the composition and the structure of the film. Both nitrogen and carbon content could raise the film hardness, on which nitrogen content did stronger effect than carbon. The smooth morphology and continuous structure was benefit of obtaining high hardness. The maximum hardness of BON film was about 10 GPa.

• Journal of Powder Materials
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• v.31 no.1
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• pp.23-29
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• 2024

This study investigates the effect of the microstructure of Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), a solid electrolyte, on its ionic conductivity. Solid electrolytes, a key component in electrochemical energy storage devices such as batteries, differ from traditional liquid electrolytes by utilizing solid-state ionic conductors. LATP, characterized by its NASICON structure, facilitates rapid lithium-ion movement and exhibits relatively high ionic conductivity, chemical stability, and good electrochemical compatibility. In this study, the microstructure and ionic conductivity of LATP specimens sintered at 850, 900, and 950℃ for various sintering times are analyzed. The results indicate that the changes in the microstructure due to sintering temperature and time significantly affect ionic conductivity. Notably, the specimens sintered at 900℃ for 30 min exhibit high ionic conductivity. This study presents a method to optimize the ionic conductivity of LATP. Additionally, it underscores the need for a deeper understanding of the Li-ion diffusion mechanism and quantitative microstructure analysis.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.405-412
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• 2009

The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.