• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.76-80
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• 2000

CF & $CF_2$ radicals in a $C_4F_8$ inductively coupled plasma were observed with laser induced fluorescence. 251.9nm UV laser was used for the $CF_2$ excitation and 265.3nm UV emitted light for the detection which has the maximum intensity among many induced fluorescence lights. In the case of CF radical detection, 232.9nm UV laser was used for the excitation and 247.6nm for the detection. $CF_2$ radical density increased toward substrate, while CF radical had its maximum at about 10nm away from the substrate. The atomic fluorine density which was studied by the actinometry increased as the position moves away from the substrate. This phenomena was thought to have a close relation with the polymer growth on the wafer. When the bias voltage increased, $CF_2$ , CF radicals decreased while the atomic fluorine increased tio some extent and then decreased, which was thought to be due to the change in the ionization and dissociation.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.374-380
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• 1998

Radical and ion densities in a $CF_4$plasma have been calculated as a function of input power density, gas pressure and feed gas flow rate using simple 0 dimensional global model. Fluorine atom is found to be the most abundant neutral particle. Highly fragmented species such as CF and $CF^+$ become dominant neutral and ionic radical at the high power condition. As the pressure increase, ion density increases but ionization rate decreases due to the decrease in electron temperature. The fractional dissociation of $CF_4$feed gas decreases with pressure after increasing at the low pressure range. Electron density and temperature are almost independent of flow rate within calculation conditions studied. The fractional dissociation of $CF_4$monotonically decreases with flow rate, which results in increase in $CF_3$and decrease in CF density. The calculation results show that the $SiO_2$etch selectivity improvement correlates to the increase in the relative density of fluorocarbon ion and neutral radicals which has high C/F ratio.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.373-375
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• 2006

$CF_4$ gas is one of the most common chemicals used for dry etching in semiconductor manufacturing processes. For application to the etching process and environmental control, the low-pressure inductively coupled plasma (LP-ICP) was employed to obtain the spectrum of $CF_4$ gas. In terms of the analysis of the spectra, trace CF radical by A-X and B-X transitions was detected. The other $CF_x$ radicals, such as $CF_2$ and $CF_3$, were not seen in this experiment whereas strong C and $C_2$ emissions, dissociation products of $CF_4$ gas, were observed.

• The Korea Journal of Herbology
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• v.29 no.6
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• pp.111-116
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• 2014

Objectives : The purpose of this study was to estimate the antioxidant activity of water extract of Cnidii Fructus (CF) and Torilis Fructus (TF) in Leydig cells. Methods : Free radical scavenging activity of CF and TF against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was determined spectrophotometrically. We investigated the effect of CF and TF in Leydig cells by MTT assay. The protective effects of CF and TF against hydrogen peroxide-induced oxidative stress in Leydig cells. Superoxide dismutase (SOD), and catalase activity assays were performed in Leydig cells. Results : The results showed that CF scavenged DPPH radical in a dose-dependent manner by up to 81.2%, TF scavenged DPPH radical in a dose-dependent manner by up to 63.8%. CF showed cell viability as 121.0, 132.7, 126.6% in 5, 10, $100{\mu}g/ml$ concentrations. TF showed cell viability as 127.5, 111.8% in 5, $100{\mu}g/ml$ concentraions, respectively. The hydrogen peroxide-induced cytotoxicity of Leydig cells were protected to 86.3% by CF at concentration of $10{\mu}g/ml$ and protected to 83.5% by TF at concentration of $100{\mu}g/ml$. Both CF and TF at all concentrations, SOD activity was not significantly changed. Catalase activity was significantly increased at 10, $100{\mu}g/ml$ concentrations of CF, respectively. TF's catalase activity showed no significant difference from that of the control. Conclusions : These results suggest that CF, as an antioxidant, protects Leydig cells in hydrogen peroxide-induced oxidative stress. know that "Kwangjebikeup" played a role in settlement and spreading of foreign knowledge to civilians.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.879-881
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• 1999

Radical and ion densities in a CF4 plasma have been calculated as a function of input power density. 9as pressure and feed gas flow rate using simple 0 dimensional global model. Fluorine atom is found to be the most abundant neutral particle. Highly fragmented species such as CF and CF+ become dominant neutral and ionic radical at the high power condition. As the pressure increases. ion density increases but ionization rate decreases due to the decrease in electron temperature. The fractional dissociation of CF4 feed gas decreases with pressure after increasing at the low pressure range. Electron density and temperature are almost independent of flow rate within calculation conditions studied. The fractional dissociation of CF4 monotonically decreases with flow rate. which results in increase in CF3 and decrease in CF density. The calculation results show that the SiO2 etch selectivity improvement correlates to the increase in the relative density of fluorocarbon ion and neutral radicals which has high C/F ratio.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.5
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• pp.542-547
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• 2008

The anti-diabetic effects of water extracts (WE) from medicinal herbs on hepatic glucose-regulating enzymes, such as glucokinase (GCK), pyruvate dehydrogenase (PDH), acetyl-CoA carboxylase (ACC) and ${\alpha}$-glucosidase, were studied using the cytosol fraction in liver and mitochondia fraction in heart of a type II diabetic animal (GK rat, Goto-Kakizaki). The free radical scavenging activity of water extracts by DPPH method was also tested. We found that free radical scavenging activity was strong in Corni fructu (CF), Mokdan Bark (MDB), Chenhwabon (CHB) and Sanyack (SY), while that of Backbocreng (BBR), Shuckgihwang (SGH) and Taecsa (TS) was lower. For GCK activity in cytosol of liver, CF and CHB had a more effective activity than other extracts. PDH activity in mitochondria fraction of heart was higher in all of the extracts, expect for the TS extract, than in the control. ACC activity in cytosol fraction of liver was significantly higher in the CF, CHB, SGH, TS and SY extracts than in the control. CF, BBR and MDB led to a decrease in the ${\alpha}$-glucosidase activity. Therefore, these results suggest that all of the extracts may be used as functional material in the development as anti-diabetic functional food and medicine.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.62-65
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• 2001

$SrBi_2Ta_2O_{9}$ thin films were etched in inductively coupled $Cl_{2}$/$CF_{4}$/Ar plasma. The maximum etch rate was 1060 $\AA\textrm{m}$/min in $Cl_{2}$/$CF_{4}$/Ar (80). The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy. The etching of SBT thin films in $Cl_{2}$/$CF_{4}$/Ar were etched by chemically assisted reactive ion etching. The small addition of $Cl_2$ into $CF_4$(20)/Ar(80) plasma will decrease the fluorine radicals and the increase Cl radical.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.393-397
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• 2002

Polyimide (PI) films have been studied widely as the interlayer dielectric materials due to a low dielectric constant, low water absorption, high gap-fill and planarization capability. The polyimide film was etched using inductively coupled plasma system. The etcying characteristics such as etch rate and selectivity were evaluated at different $CF_4/(CF_4+O_2)$chemistry. The maximum etch rate was 8300 ${\AA}/min$ and the selectivity of polyimide to SiO$_2$was 5.9 at $CF_4/(CF_4+O_2)$ of 0.2. Etch profile of polyimide film with an aluminum pattern was measured by a scanning electron microscopy. The vertical profile was approximately $90^{\circ}$ at $CF_4/(CF_4+O_2)$ of 0.2. As 20% $CF_4$ were added into $O_2$ plasma from the results of the optical emission spectroscopy, the radical densities of fluorine and oxygen increased with increasing $CF_4$ concentration in $CF_4/O_2$ from 0 to 20%, resulting in the increased etch rate. The surface reaction of etched PI films was investigated using x-ray photoelectron spectroscopy.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.422-429
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• 2011

Dependence of radical and ion density on electron density and temperature is numerically investigated for $Cl_2$/Ar, $CF_4$, $CF_4/O_2$, $CF_4/H_2$, $C_2F_6$, $C_4F_8$ and $SF_6$ discharges which are widely used for etching process. We derived a governing equation set for radical and ion densities as functions of the electron density and temperature, which are easier to measure relatively, from continuity equations by assuming steady state condition. Used rate coefficients of reactions in numerical calculations are directly produced from collisional cross sections or collected from various papers. If the rate coefficients have different values for a same reaction, calculation results were compared with experimental results. Then, we selected rate coefficients which show better agreement with the experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.74-77
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• 2002

Ferroelectric Random Access Memory(FRAM) and MEMS applications require noble metal or refractory metal oxide electrodes. In this study, Ru thin films were etched using $O_2$+10% $CF_4$ plasma in an inductively coupled plasma(ICP) etching system. The etch rate of Ru thin films was examined as function of rf power, DC bias applied to the substrate. The enhanced etch rate can be obtained not only with increasing rf power and DC bias voltage, but also with small addition $CF_4$ gas. The selectivity of $SiO_2$ over Ru are 1.3. Radical densities of oxygen and fluorine in $CF_4/O_2$ plasma have been investigated by optical emission spectroscopy(OES). The etching profiles of Ru films with an photoresist pattern were measured by a field emission scanning electron microscope (FE-SEM). The additive gas increases the concentration of oxygen radicals, therefore increases the etch rate of the Ru thin films and enhances the etch slope. In $O_2$+10% $CF_4$ plasma, the etch rate of Ru thin films increases up to 10% $CF_4$ but decreases with increasing $CF_4$ mixing ratio.