• Corrosion Science and Technology
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• v.9 no.6
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• pp.276-280
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• 2010

Copper(Cu) as an interconnecting metal layer can replace aluminum (Al) in IC fabrication since Cu has low electrical resistivity, showing high immunity to electromigration compared to Al. However, it is very difficult for copper to be patterned by the dry etching processes. The chemical mechanical polishing (CMP) process has been introduced and widely used as the mainstream patterning technique for Cu in the fabrication of deep submicron integrated circuits in light of its capability to reduce surface roughness. But this process leaves a large amount of residues on the wafer surface, which must be removed by the post-CMP cleaning processes. Copper corrosion is one of the critical issues for the copper metallization process. Thus, in order to understand the copper corrosion problems in post-CMP cleaning solutions and study the effects of DC biases and post-CMP cleaning solution concentrations on the Cu film, a constant voltage was supplied at various concentrations, and then the output currents were measured and recorded with time. Most of the cases, the current was steadily decreased (i.e. resistance was increased by the oxidation). In the lowest concentration case only, the current was steadily increased with the scarce fluctuations. The higher the constant supplied DC voltage values, the higher the initial output current and the saturated current values. However the time to be taken for it to be saturated was almost the same for all the DC supplied voltage values. It was indicated that the oxide formation was not dependent on the supplied voltage values and 1 V was more than enough to form the oxide. With applied voltages lower than 3 V combined with any concentration, the perforation through the oxide film rarely took place due to the insufficient driving force (voltage) and the copper oxidation ceased. However, with the voltage higher than 3 V, the copper ions were started to diffuse out through the oxide film and thus made pores to be formed on the oxide surface, causing the current to increase and a part of the exposed copper film inside the pores gets back to be oxidized and the rest of it was remained without any further oxidation, causing the current back to decrease a little bit. With increasing the applied DC bias value, the shorter time to be taken for copper ions to be diffused out through the copper oxide film. From the discussions above, it could be concluded that the oxide film was formed and grown by the copper ion diffusion first and then the reaction with any oxidant in the post-CMP cleaning solution.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.323-329
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• 2000

In this study we have calculated an ideal complex refractive index of a TiN trim used in a layer of anl1reilecnon (I\R) coatmg, [air$ISiO_2ITiNIglass$] in the visible. Also we simulated the rellectance of lwo-layer AR coating by varying the thicknesses of TiN and $SiO_2$ layers, respecl1vely. The simolation results show that we can controllhe lowest reflectance and AR band of tile AR coating. The TIN fihns were fabricated by a RF magnetron sputtering apparalus. The chemical, structural and electrical properties of TiN fih11S were inveshgated by the Rutherford backscattering spech'oscopy (RBS), atomic force microscope (AFM) and 4-point probe. The optical properlies were inve,tigated by the spectrophotometer and vanable angle spectroscopic ellipsometer (VASE). The smface roughness of TiN flhns \vas $9~10\AA$. TIle resistivity of TiN films was TEX>$360~730\mu$\Omega $ cm. The ,toichlOllletry of TiN film was 1'1: O:N = I: 0.65 :0.95 and ilic oxygen wa~ found on ilie smface. With these experimental and simu]al1on resulLs, we deposited duo: two-layer AR coating, [air$ISiO_2ITiNIglass$] and the refleClance was under 0.5% ill the regIOn of 440-650 run. 0 run.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.111-120
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• 1999

The effects of annealing in rotating magnetic field after deposition on electromagnetic properties of $Co_{82}Zr_6Mo_{12}$ thin (200~1200 $\AA$) films prepared by RF-magnetron sputtering were investigated in terms of microstructure and surface morphology. The coercivity decreases, but $4{\pi}M_5$ does not change with increasing the film thickness. The coercivity of the films was decreased below 300 $^{\circ}C$ due to stress relief and decreasing the surface roughness, while increased at 400 $^{\circ}C$ due to partial grain growth. And then, $4{\rho}M_5$ was almost independent of annealing temperatures below 200 $^{\circ}C$, but increased from 7.4 kG to 8.0 kG at 300 $^{\circ}C$ and at 400 $^{\circ}C$, which was caused by precipitation and growth of fine Co particles in the films. The electrical resistivity of films was decreased with increasing annealing temperatures and the magnetoresistance was a negative value of nearly 0 $\mu$$\Omega$cm. After annealing at 300 $^{\circ}C$, maximum effective permeability was 1200 to the hard axis of the thin films according to high frequency change. Considering the practical application of biasing layers of the films for magnetoresistive heads, optimal annealing conditions was obtained after one hour annealing at 300 $^{\circ}C$ in 400 Oe rotating magnetic field.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.723-731
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• 1995

P $b_2$S $r_2$( $Y_{1-x}$ C $a_{x}$)C $u_3$ $O_{8+}$$\delta$/ samples were prepared with x=0.4~0.6 and small $\delta$. To minimize the extent of oxidative decomposition reaction which occurs during the preparation of this phase, two annealing steps were adopted : First, sintered samples of P $b_2$S $r_2$( $Y_{1-x}$ C $a_{x}$)C $u_3$ $O_{8+}$$\delta$/ are oxygenated under 100% $O_2$, which leads to a large $\delta$(e.g., $\delta$=1.8). Second, the resulting samples are deoxygenated under 0.1~1.0% $O_2$in $N_2$, lowering $\delta$ to desired values. This two-step annealing procedure minimized the extent of oxidative decomposition. However, even with the two-step annealing procedure, the oxidative decomposition of P $b_2$S $r_2$( $Y_{1-x}$ C $a_{x}$)C $u_3$ $O_{8+}$$\delta$/ cannot be completely suppressed if $\delta$ is to be reduced to maximize $T_{c}$. Electrical resistivity data show that $T_{c}$(onset) is a function of hole concentration in the Cu $O_2$layer, and the optimum hole concentration for the maximum $T_{c}$ is achieved when $Ca^{2+}$is substituted for $Y^{3+}$between 0.5 and 0.6 A $T_{c}$(onset)=80K has been observed for one such sample, and this is the highest $T_{c}$(onset) yet reported for this compound.ed for this compound.nd.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.400-406
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• 1997

The electrical and physical characteristics of aluminum oxide and Pt thin films on it, deposited by reactive sputtering and DC magnetron sputtering, respectively, were analyzed with increasing annealing temperature($400{\sim}800^{\circ}C$) by four point probe, SEM and XRD. Under $600^{\circ}C$ of annealing temperature, aluminum oxide had the properties of improving Pt adhesion to $SiO_{2}$ and insulation without chemical reaction to Pt thin films and the resistivity of Pt thin films was improved. But these properties of aluminum oxide and Pt thin films on it were degraded over $700^{\circ}C$ of annealing temperature because aluminum oxide was changed into metal aluminum and then reacted to Pt thin films deposited on it. The thermal characteristics of Pt micro heater were analyzed with Pt-RTD integrated on the same substrate. In the analysis of properties of Pt micro heater, active area was smaller size, Pt micro heater had better thermal characteristics. The temperature of Pt micro heater with active area, $200{\mu}m{\times}200{\mu}m$ was up to $400^{\circ}C$ with 1.5watts of the heating power.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.305-312
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• 2017

In our society, the advanced, advanced, and information industries have continued to grow and now live in the era of the fourth industrial revolution. As the industry develops, the load of the users has also increased so much that it is deepened by the energy shortage phenomenon and the construction of additional energy facilities is required. Therefore, energy plant construction work is being actively carried out in the coastal area. In particular, it is common to build a plant in the ground by filling the coast with soil in other regions, reflecting the fact that Korea is lacking in the country when constructing power plants, gas and petrochemical plants. Current domestic grounding designs are designed or constructed to suit only the use of grounding resistors based on the electrical equipment design technical standards. However, in the case of a plant facility constructed in the untested buried soil, when the lightning current and the abnormal current are inputted, the facility operator or the user due to the elevation of the ground potential is seriously exposed to the risk of electric shock disaster. In this paper, we analyze the ground resistivity of the landfilled soil and use a computer program (CDEGS) based on KS C IEC 61936-1, We analyze the contact voltage and stratification voltage and propose a grounding design optimized for plant installation.

• Resources Recycling
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• v.18 no.1
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• pp.38-43
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• 2009

In this study, binderless consolidation processes of ultra foe Si powder, by-products of making high purity poly-Si in the current method, were systematically investigated for use as economical solar-grade feedstock. The average diameter of the silicon powder was $7.8{\mu}m$. The main contaminants of the fine silicon powder were $SiO_2$ type oxide and humidity. The chemical pretreatment using the HF solution was observed to be effective for the improvement of the compactability of the silicon powder and the density ratio and the strength of the silicon powder compacts. The yield of the binder-free consolidation process increased by 20% under a vacuum condition. In as-received state, the silicon powder were not pure enough to be used as solar grade feed-stock material. After the dry chemical treatments, a sufficiently high purity above solar-grade was able to be achieved.

• Journal of Soil and Groundwater Environment
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• v.14 no.5
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• pp.29-40
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• 2009

In general, understanding groundwater flow in fractured bedrock is critical during tunnel and underground cavern construction. In that case, borehole data may be useful to examine groundwater flow properties of the fractured bedrock from pre-excavation until completion stages, yet sufficient borehole data is not often available to acquire. This study evaluated groundwater discharge rate into Jikri tunnel in Gyeonggi province using hydraulic parameters, groundwater level data in the later stage of tunneling, national groundwater monitoring network data, and electrical resistivity survey data. Groundwater flow rate into the tunnel by means of analytical method was estimated $7.12-74.4\;m^3/day/m$ while the groundwater flow rate was determined as $64.8\;m^3/day/m$ by means of numerical modeling. The estimated values provided by the numerical modeling may be more logical than those of the analytical method because the numerical modeling could take into account spatial variation of hydraulic parameters that was not possible by using the analytical method. Transient modeling for a period of one year from the tunnel completion resulted in the recovery of pre-excavation groundwater level.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.14-15
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• 2010

Recently there has been growing interest in topological insulators or the quantum spin Hall (QSH) phase, which are insulating materials with bulk band gaps but have metallic edge states that are formed topologically and robust against any non-magnetic impurity [1]. In a three-dimensional material, the two-dimensional surface states correspond to the edge states (topological metal) and their intriguing nature in terms of electronic and spin structures have been experimentally observed in bulk Bi1-xSbx single crystals [2,3,4]. However, if we want to know the transport properties of these topological metals, high purity samples as well as very low temperature will be needed because of the contribution from bulk states or impurity effects. In a recent report, it was also shown that an intriguing coupling between the surface and bulk states will occur [5]. A simple solution to this bothersome problem is to prepare a topological metal on an ultrathin film, in which the surface-to-bulk ratio is drastically increased. Therefore in the present study, we have investigated if there is a method to make an ultrathin Bi1-xSbx film on a semiconductor substrate. From reflection high-energy electron diffraction observation, it was found that single crystal Bi1-xSbx films (0${\sim}30\;{\AA}A$ can be prepared on Si(111)-$7{\times}7$. The transport properties of such films were characterized by in situ monolithic micro four-point probes [6]. The temperature dependence of the resistivity for the x=0.1 samples was insulating when the film thickness was $240\;{\AA}A$. However, it became metallic as the thickness was reduced down to $30\;{\AA}A$, indicating surface-state dominant electrical conduction. Figure 1 shows the Fermi surface of $40\;{\AA}A$ thick Bi0.92Sb0.08 (a) and Bi0.84Sb0.16 (b) films mapped by angle-resolved photoemission spectroscopy. The basic features of the electronic structure of these surface states were shown to be the same as those found on bulk surfaces, meaning that topological metals can be prepared at the surface of an ultrathin film. The details will be given in the presentation.

• Geophysics and Geophysical Exploration
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• v.22 no.3
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• pp.132-148
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• 2019

Recently, safety and environmental concerns have become major social issues. Especially, a special underground-safety law has been made and enacted to prevent ground subsidence around construction sites. For environmental problems, several researches have started or will start on characterization of contaminated sites, in-situ environmental remediation in subsurface, and monitoring of remediation results. As a part of the researches, geophysical surveys, which have been mainly applied to explore mineral resources, geological features or ground, are used to characterize not only contaminated areas but also fluid flow paths in subsurface environments. As a basic study for the application of geophysical surveys to detect contamination in subsurface, this paper analyzes previous researches to understand changes in geophysical properties of contaminated zones by various contaminants such as leachate, heavy metals, and non-adequate phase liquid (NAPL). Furthermore, this paper briefly introduces how geophysical surveys like direct-current electrical resistivity, induced polarization and ground penetration radar surveys can be applied to detect each contamination, before analyzing case studies of the applications in contaminated areas by NAPL, leachate, heavy metal or nitrogen oxides.