• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.38-41
• /
• 2004

The oxidizer plays an important role in the metal chemical mechanical polishing(CMP) slurry. Currently, the oxidizer used in CMP slurry is nearly divided into several kinds such as $Fe(NO_3)_3$, $H_2O_2$, $KIO_3$, and $H_5IO_6$. It is generally known that oxidizer character of $H_2O_2$ is more effective than other oxidizers. In this work, we have been studied the characteristics for the $H_2O_2$ concentration of copper slurry, which can applicable in the recent semiconductor manufacturing process. Also, it plays an important role in the planarization of copper films using copper slurries during micro-electronic device fabrication. In this work, we confirmed that removal rate of Cu/TaN changed by $H_2O_2$ concentration on copper slurry. And we used $KMnO_4$ in the measurement method of $H_2O_2$. In analysis results, we confirmed that the difference of results is large. We thought that the difference was due to organic component existence. So in titration method of $H_2O_2$ concentration, we used $Na_2S_2O_3$ instead of $KMnO_4$ as solution. Consequently, using the titration method, we could calculate correct data reduced error. And $H_2O_2$ concentration has been adjusted to the target concentration of 0.1 wt%.

• Korean Journal of Materials Research
• /
• v.9 no.5
• /
• pp.509-514
• /
• 1999

Interest in the integrated capacitors, which make it possible to reduce the size of and to obtain improved electrical performance of an electronic system, is expanding. In this study, $Ta_2$O\ulcorner thin film capacitors for MCM integrated capacitors were fabricated on a Upilex-S polymer film by DC magnetron reactive sputtering and the effects of low temperature annealing at various atmospheres and substrate surface morphology on the capacitor characteristics were discussed. The low temperature($150^{\circ}C$) annealing produced improved capacitor yield irrespective of the annealing at mosphere. But the leakage current of the $O_2$-annealed film was larger than that of any other films. This is presumably mosphere. But the leakage current of the $O_2$-annealed film was larger than that of any other films. This is presumably due to the change of the $Ta_2$O\ulcorner film surface by oxygen, which was explained by conduction mechanism study. Leakage current and breakdown field strength of the capacitors fabricated on the Upilex-S film were 7.27$\times$10\ulcornerA/$\textrm{cm}^2$ and 1.0 MV/cm respectively. These capacitor characteristics were inferior to those of the capacitors fabricated on the Si substrate but enough to be used for decoupling capacitors in multilayer package. Roughness Analysis of each layer by AFM demonstrated that the properties of the capacitors fabricated on the polymer film were affected by the surface morphology of the substrate. This substrate effect could be classified into two factors. One is the surface morphology of the polymer film and the other is the surface morphology of the metal bottom electrode determined by the deposition process. Therefore, the control of the two factors is important to obtain improved electrical of capacitors deposited on a polymer film.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.2
• /
• pp.329-341
• /
• 2017

A multi-server architecture has been proposed to increase the efficiency of resources due to the rapid growth of computer networks and service providing servers. The smartcard-based authentication protocol in the multi-server environments has been continuously developed through various studies. Recently, Chun-Ta Li et al proposed an authentication protocol that solves Xiong Li el al's authentication protocol vulnerability to user impersonation attack and session key disclosure attack. However, Chun-Ta Li et al's authentication protocol has a problem with user impersonation in the vulnerability analysis and has an unsuitable authentication process. Therefore, this paper proposes a smartcard-based authentication protocol in the multi-server environments that solves the denial of service attack and replay attack vulnerabilities of the authentication protocol proposed by Xiong Li et al.

• The Korean Journal of Ceramics
• /
• v.6 no.3
• /
• pp.276-279
• /
• 2000

Ferroelectric properties of $SrBi_2TaNbO_9$ (SBTN) thin films were changed by the amount of Bi content in SBTN. We suggested that the addition of excess Bi into the films could be accomplished by heat-treating $SBTN/Bi_2O_3/SBTN$ heterostructure fabricated by r.f. magnetron sputtering method. Excess Bi composition was controlled by the thickness of the sandwiched $Bi_2O_3$ from 0 to $400\;\AA$. When the SBTN thin films were inserted by $400\;{\AA}\;Bi_2O_3$ layer, $Bi_2Pt$ phase was formed as a second phase in SBTN films, resulting in poor ferroelectric properties. The onset temperature for hysteresis loop can be reduced by heat treating $SBTN/Bi_2O_3/SBTN$ heterostructure. The films with $SBTN/Bi_2O_3(100\;{\AA})/SBTN$ hetero-structure followed by annealing at $650^{\circ}C$ for 30 min show 2Pr and Ec of $5.66\;{\mu}C/\textrm{cm}^2$ and 54 kV/cm, respectively.

• Journal of the Korean Chemical Society
• /
• v.36 no.2
• /
• pp.185-190
• /
• 1992

Near-IR spectra for $ν_{\alpha}$+ Amide Ⅱ combination band of thioamides, and very dilute thioamide-DMSO solution in CCl4 were recorded in the temperature range of $5^{\circ}C$ to $55^{\circ}C$. This combination band was resolved by the computer program into two Lorentzian-Gaussian product function which have been identified with monomeric thioamide and thioamide-DMSO 1 : 1 complex. Equilibrium constants and thermodynamic parameters for the thioamide-DMSO hydrogen bonding were elucidated by the analysis of conce ntration and temperature dependent spectra. The hydrogen bonding strength between thioacetamide (TA) and DMSO in $CCl_4$ is stronger than that between thiopropionamide (TPA) and DMSO in CCl4. The ${\Delta}H^{\circ}$ for the TA-DMSO and TPA-DMSO 1 : 1 complex in CCl4 were -15.3 kJ${\cdot}$$mol^{-1}$ and -14.2 kj${\cdot}$$mol^{-1}$, respectively.

• Journal of the East Asian Society of Dietary Life
• /
• v.26 no.2
• /
• pp.192-199
• /
• 2016

The antioxidative activity and antimutagenic activity of the ethanol extracts from pericarp and seeds of wild grape (Vitis coignetiea) were analyzed in this study. The antioxidative activity of the extracts from wild grape was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The antimutagenic activity of the extracts was evaluated on Salmonella typhimurium TA98 and TA100 by Ames test using 4-nitroquinoline 1-oxide (4-NQO) and sodium azide as mutagens. In the antioxidative activity determination, $IC_{50}$ values of the DPPH radical scavenging activity of the extracts from pericarp and seeds were 27.16 ppm and 7.61 ppm, respectively. Additionally, ABTS radical scavenging activities of pericarp and seed extract were 99.75% and 98.87% at 200 ppm, respectively. In the antimutagenic activity determination, pericarp extract at 5 mg/plate inhibited 72.6% and 74.3% of mutagenicity of S. typhimurium TA98 induced by 4-NQO and sodium azaid, respectively. Also, the mutagenicity inhibition rates of seed extract at 5 mg/plate were 77.8% and 74.5% in S. typhimurium TA100 induced by 4-NQO and sodium azaid, respectively. These results demonstrate that the ethanol extract from wild grape has remarkable antioxidant activity and antimutagenicity.

• Journal of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.265-270
• /
• 1985

Ta$_2$O$_5$, Nb$_2$O$_5$, SnO$_2$ and ZrO$_2$ in tin-slag samples were determined by X-ray fluorescence spectrometry using the dilution parameter method and the analytical results were compared with the data obtained by standard calibration curve method. Tin-slag samples and one standard sample having very similar composition to the tin-slags were diluted with a proper diluent (La$_2$O$_3$) to the ratio of 1: 1, 1 : 2, 1 : 3 and 1 : 4. After measuring the X-ray intensities of original and diluted samples, the values of dilution parameters were calculated by using the dilution parameter equation. Without any calibration curve, the analytical results were calculated from the equation including the dilution parameter term. The results were in good agreement with the reference data by the standard calibration curve method.

• Korean Chemical Engineering Research
• /
• v.44 no.6
• /
• pp.614-622
• /
• 2006

A Study on the characteristics of $Ta/Ta_2O_5/MnO_2$ capacitor applied $MnO_2$ by means of pyrolysis of manganese nitrate solution was carried out. Single phase of $MnO_2$ was obtained in the pyrolysis temperature range of 230 to $250^{\circ}C$ by TG/DSC analysis on manganese nitrate solution. Temperature of pyrolysis, concentration of manganese nitrate solution and the number of pyrolysis were selected for the basic parameters of embodying $MnO_2$ solid electrolyte and then the effects of these parameters on the characteristics of capacitor were estimated. The characteristics of capacitor pyrolyzed radiationally was superior to that of capacitor pyrolyzed convectionally on the basis of these optimized parameter conditions. It was verified that radiational pyrolysis formed smaller spherical $MnO_2$ particles than those of convectional one relatively and these facts resulted in forming uniform and dense solid electrolyte layer into the microporous sintered body of capacitor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.41-43
• /
• 1999

Among the feffoelectric thin films that have been widely investigated for ferroelectric random access memory (FRAM) applications, SrBi$_2$Ta$_2$$O_{9}$ thin film is appropriate to memory capacitor materials for its excellent fatigue endurance. However, very few studies on etch properties of SBT thin film have been reported although dry etching is an area that demands a great deal of attention in the very large scale integrations. In this study, the a SrBi$_2$Ta$_2$$O_{9}$ thin films were etched by using magnetically enhanced inductively coupled Ar/CHF$_3$ plasma. Etch properties, such as etch rate, selectivity, and etched profile, were measured according to gas mixing ratio of CHF$_3$(Ar$_{7}$+CHF$_3$) and the other process conditions were fixed at RF power of 600 W, dc bias voltage of 150 V, chamber pressure of 10 mTorr. Maximum etch rate of SBT thin films was 1750 A77in, under CHF$_3$(Ar+CHF$_3$) of 0.1. The selectivities of SBT to Pt and PR were 1.35 and 0.94 respectively. The chemical reaction of etched surface were investigated by X-ray photoelectron spectroscopy (XPS) analysis. The Sr and Ta atoms of SBT film react with fluorine and then Sr-F and Ta-F were removed by the physical sputtering of Ar ion. The surface of etched SBT film with CHF$_3$(Ar+CHF$_3$) of 0.1 was analyzed by secondary ion mass spectrometer (SIMS). Scanning electron microscopy (SEM) was used for examination of etched profile of SBT film under CHF$_3$(Ar+CHF$_3$) of 0.1 was about 85˚.85˚.˚.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.12
• /
• pp.1425-1433
• /
• 2011

We investigated an early rehabilitation training system that increase the intensity of patient rehabilitation training to shorten the time it takes for patients to progress to a secondary rehabilitation training stage by allowing patients incapable of self-ambulation. It consisted of tilting bed, unstable platform using strong springs and training program for lower limb rehabilitation. We performed experimental study on the muscular activities of tibialis anterior(TA), soleus(SO), gastrocnemius(GA) in the lower extremities during training of straight line, circle, quardrangle pattern during tilting angle of $30^{\circ}$, $60^{\circ}$. The muscle activities were higher during tilting angle of $30^{\circ}$ than $60^{\circ}$. In straight line pattern, the muscle activities were higher by SO, GA and TA during medio-lateral direction, however, by TA, SO and GA during anterio-posterior direction. In circle and quardrangle pattern, the muscle activities were higher by TA, SO and GA during clockwise and counterclockwise direction. The results indicate that the early rehabilitation training system could be applied to improve the lower extremity muscular strength for elderly and patients, especially, stroke.