• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.250-251
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• 2009

For the fabrication of a multilevel resist (MLR) based on a very thin amorphous carbon (a-C) layer an $Si_{3}N_{4}$ hard-mask layer, the selective etching of the $Si_{3}N_{4}$ layer using physical-vapor-deposited (PVD) a-C mask was investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in $CH_{2}F_{2}/H_{2}/Ar$ plasmas : HF/LF powr ratio ($P_{HF}/P_{LF}$), and $CH_{2}F_{2}$ and $H_2$ flow rates. It was found that infinitely high etch selectivities of the $Si_{3}N_{4}$ layers to the PVD a-C on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The $H_2$ and $CH_{2}F_{2}$ flow ratio was found to play a critical role in determining the process window for infinite $Si_{3}N_{4}$/PVDa-C etch selectivity, due to the change in the degree of polymerization. Etching of ArF PR/BARC/$SiO_x$/PVDa-C/$Si_{3}N_{4}$ MLR structure supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the $Si_{3}N_{4}$ layer.

• Journal of Adhesion and Interface
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• v.8 no.1
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• pp.15-27
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• 2007

Polyimide (PI) surface modification was carried out by ion-beam treatment and silane-imidazole coupling agent to improve the adhesion between polyimide film and copper. Silane-imidazole coupling agent contains imidazole functional groups for the formation of a complex with copper metal through a coordination bonding and methoxy silane groups for the formation of siloxane polymers. The PI film surface was first treated by argon (Ar)/oxygen ($O_2$) ion-beam, followed by dipping it into a modified silane-imidazole coupling agent solution. The results of X-ray photoelectron spectroscopy (XPS) spectra revealed that the $Ar/O_2$ plasma treatment formed oxygen functional groups such as hydroxyl and carbonyl groups on the polyimide film surface and confirmed that the PI surface was modified by a coupling reaction with imidazole-silane coupling agent. Adhesion between copper and the treated PI film by ion-beam and coupling agent was superior to that with untreated PI film. In addition, adhesion of PI film treated by an $Ar/O_2$ plasma to copper was better than that of PI film treated by a coupling agent. The peeled-off layers from the copper-PI film joint were completely different in chemical composition each other. The layer of PI film side showed similar C1s, N1s, O1s spectra to the original Upilex-S and no Si and Cu atoms appeared. On the other hand the layer of copper side showed different C1s and N1s spectra from the original PI film and many Si and Cu atoms appeared. This indicates that the failure occurs at an interface between the imidazole-silane and PI film layers rather than within the PI layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.142-145
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• 2004

In this work, we have investigated the application of rapid thermal processing (RTP) and plasma enhanced chemical vapour deposition (PECVD) for surface passivation. Rapid thermal oxidation (RTO) has sufficiently low surface recombination velocities (SRV) $S_{eff}$ in spite of a thin oxides and short process time. The effective lifetime is increasing with an increase of the oxide thickness. In the same oxide thickness, The effective lifetime is independent on the process temperature and time. $S_{eff,max}$ is exponentially decreased with increasing oxide thickness. $S_{eff,max}$ can be reduced to 200 cm/s with only 10 nm oxide thickness. On the other hand, three different types of SiN are reviewed. SiN1 layer has a thickness of about 72 nm and a refractive index of 2.8. Also, The SiN1 has a high passivation quality. The effective lifetime and SRV of 1 $\Omega$ cm Float zone (FZ) silicon deposited with SiN1 is about 800 s and under 10 cm/s, respectively. The SiN2 is optimized for the use as an antireflection layer since a refractive index of 2.3. The SiN3 is almost amorphous silicon caused by less contents of N2 from total process. The effective lifetime on the FZ 1 ${\Omega}cm$ is over 1000 ${\mu}s$.

• Journal of Nutrition and Health
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• v.40 no.7
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• pp.606-615
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• 2007

This study was performed to investigate anti-thrombogenic, anti-inflammatory effects of n-BuOH (B) and $CH_2Cl_2$ (MC) fractions extracted from Sancho (Zanthoxylum. schinifolium) leaves in rats fed high fat diets. The experimental animal groups were consisted of eight including one 5% fat (N) and one 20% fat (H) without the test materials in diets and six H groups of feeding three levels (50, 100 and 150 mg/day) of the B and the MC fractions from Z. schinifolium, respectively. Plasma activated partial thromboplastin times and thrombin times of H group were decreased compared to the N group, but they were increased by feeding the MC fraction of 50 mg and over. Polymorphonuclear leukocyte 5#-lipo-xygenase activities and leukotriene $B_4$ contents of the H group were significantly increased compared to the N group, but they were decreased in the 100 mg and 150 mg of B fraction or the 150 mg of MC fraction fed groups. Liver cytochrome $P_{450}$, $O_2^-$, $H_2O_2$ and GSSG contents were increased by the high fat diet but decreased by feeding the B fraction or the MC fraction, while GSH content and glutathione S-transferase activity lowered by high fat diet were increased by feeding the two solvent fractions. The effects of the solvent fractions were evident at the level of 100 mg/day and over. The present results confirmed that two solvent fractions from the leaves of Z, schinifolium have enhancing effects on anti-thrombosis and anti-inflammation partly by antioxidant action and partly by direct modulation of the respective processeds. In conclusion, the n-BuOH and $CH_2Cl_2$ fractions from leaves of Z, schinifolium can be utilized as the proper ingredients of functional foods for preventing chronic degenerative disease.

• Journal of Life Science
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• v.24 no.8
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• pp.873-879
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• 2014

The constituents from the needles of the pine tree, Pinus densiflora, were purified and investigated for antithrombotic activity. The needles were initially extracted three times with 70% ethanol, and the extract was sequentially fractionated with chloroform and n-butanol. The aqueous layer formed after n-butanol fractionation was subjected to purification by medium pressure and high pressure liquid chromatography. The two neolignans, 2, 3-dihydro-7-hydroxyl-3-hydroxymethyl-2-(4'-hydroxyl -3-methoxyphenyl)-5-benzofuranpropanol-3-O-${\alpha}$-rhamnopyranoside (a neolignan glycoside) and 2, 3-dihyro-3-hydroxymethyl-7-methoxy-2-(4'-hydroxyphenyl-3'-methoxy)-5-benxofuran propanol 4'-O-${\alpha}$-rhamnopyranoside (icariside $E_4$) were identified by $^1H$ and $^{13}C$ NMR spectra. The effect of the purified compounds, the neolignan glycoside and icariside $E_4$ on thrombin inhibition were investigated by measuring thrombin clotting time in plasma. As a result, the clotting of the neolignan glycoside was delayed four times compared to that of icariside $E_4$. In addition, an analysis of the inhibition effect by changing the concentration showed that the clotting time was delayed in accordance with an increase in the concentration of the neolignan glycoside. Furthermore, we examined the interaction of thrombin and fibrinogen to clarify the action mechanism. As a result, the delay of clotting time in the response of thrombin and pure fibrinogen may indicate that neolignan glycosides inhibit the thrombin action in a direct manner, leading to the suppression of fibrin generation.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.291-291
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• 2010

Electron-beam lithography (EBL) process is a versatile tool for a fabrication of nanostructures, nano-gap electrodes or molecular arrays and its application to nano-device. However, it is not appropriate for the fabrication of sub-5 nm features and high-aspect-ratio nanostructures due to the limitation of EBL resolution. In this study, the precision assembly and alignment of DNA molecule was demonstrated using sub-5 nm nanostructures formed by a combination of conventional electron-beam lithography (EBL) and plasma ashing processes. The ma-N2401 (EBL-negative tone resist) nanostructures were patterned by EBL process at a dose of $200\;{\mu}C/cm2$ with 25 kV and then were ashed by a chemical dry etcher at microwave (${\mu}W$) power of 50 W. We confirmed that this method was useful for sub-5 nm patterning of high-aspect-ratio nanostructures. In addition, we also utilized the surface-patterning technique to create the molecular pattern comprised 3-(aminopropyl) triethoxysilane (APS) as adhesion layer and octadecyltrichlorosilane (OTS) as passivation layer. DNA-templated gold nanoparticle chain was attached only on the sub-5 nm APS region defined by the amine groups, but not on surface of the OTS region. We were able to obtain DNA molecules aligned selectively on a SiO2/Si substrate using atomic force microscopy (AFM).

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.168-168
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• 2011

정보화 사회가 도래함으로 개인별 정보 이용량이 급격히 증가하였고 스마트폰과 같은 모바일 기기의 개발로 정보 이용량이 최고치를 갱신 중이다. 이러한 흐름 속에 사람들은 빠른 처리 속도와 고도의 저장 능력을 요구하게 되고 이에 따라 새로운 Random Access Memory에 대한 연구가 활발히 진행되고 있다. 현재 Dynamic Random Access Memory (DRAM)가 눈부신 발전과 성과를 이룩하고 있지만 전원 공급이 중단 될 경우 저장된 내용들이 지워진다는 단점을 가지고 있다. DRAM의 장점에 이러한 단점을 보완할 수 있는 차세대 반도체 소자로 주목 받고 있는 것이 Magnetic Random Access Memory (MRAM)이다. DRAM에서 Capacitor와 유사한 기능을 하는 MTJ stack은 tunneling magnetoresistance (TMR) 현상을 나타내는 자기저항 박막을 이용하여 MRAM 소자에 집적된다. 본 연구에서는 MRAM의 자성 재료로 구성된 MTJ stack을 효과적으로 식각하고 우수한 식각 profile을 얻는 동시에 재증착의 문제를 해결하는데 목적을 둔다. 본 IrMn 자성 박막의 식각 연구는 유도결합 플라즈마 반응성 이온 식각 (Inductively Coupled Plasma Reactive Ion Etching: ICPRIE)법을 이용하여 진행되었다. 특히 본 연구에서는 종래의 $Cl_2$, $BCl_3$ 그리고 HBr과 같은 부식성 가스가 아닌 부식성이 없는 $CH_4$가스를 선택하여 그 농도를 변화시키면서 식각하였고 더 나아가 $O_2$를 첨가하면서 그 효과를 극대화하려고 시도하였다. IrMn 자성 박막의 식각 속도, TiN 하드 마스크에 대한 식각 선택도 그리고 profile 등이 조사되었고 최종적으로 X-ray photoelectron spectroscopy (XPS)를 이용하여 식각 메카니즘을 이해하려고 하였다.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.414-420
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• 2001

A 30-kV plasma immersion ion implantation setup (P $I^3$) has been equipped with a self-developed 6'-magnetron to perform hard coatings with enhanced adhesion by P $I^3$D(P $I^3$ assisted deposition) process. Using ICP source with immersed Ti antenna and reactive magnetron sputtering of Ti target in $N_2$/Ar ambient gas mixture, the TiN films were prepared on Si substrates at different pulse bias and ion-to-atom arrival ratio ( $J_{i}$ $J_{Me}$ ). Prior to TiN film formation the nitrogen implantation was performed followed by deposition of Ti buffer layer under A $r^{+}$ irradiation. Films grown at $J_{i}$ $J_{Me}$ =0.003 and $V_{pulse}$=-20kV showed columnar grain morphology and (200) preferred orientation while those prepared at $J_{i}$ $J_{Me}$ =0.08 and $V_{pulse}$=-5 kV had dense and eqiaxed structure with (111) and (220) main peaks. X-ray diffraction patterns revealed some amount of $Ti_{x}$ $N_{y}$ in the films. The maximum microhardness of $H_{v}$ =35 GN/ $M^2$ was at the pulse bias of -5 kV. The P $I^3$D technique was applied to enhance wear properties of commercial tools of HSS (SKH51) and WC-Co alloy (P30). The specimens were 25-kV PII nitrogen implanted to the dose 4.10$^{17}$ c $m^{-2}$ and then coated with 4-$\mu\textrm{m}$ TiN film on $Ti_{x}$ $N_{y}$ buffer layer. Wear resistance was compared by measuring weight loss under sliding test (6-mm $Al_2$ $O_3$ counter ball, 500-gf applied load). After 30000 cycles at 500 rpm the untreated P30 specimen lost 3.10$^{-4}$ g, and HSS specimens lost 9.10$^{-4}$ g after 40000 cycles while quite zero losses were demonstrated by TiN coated specimens.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.17-17
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• 2010

The amorphous $Bi_5Nb_3O_{15}$ film grown at room temperature under an oxygen-plasma sputtering ambient (BNRT-$O_2$ film) has a hydrophobic surface with a surface energy of $35.6\;mJm^{-2}$, which is close to that of the orthorhombic pentacene ($38\;mJm^{-2}$, resulting in the formation of a good pentacene layer without the introduction of an additional polymer layer. This film was very flexible, maintaining a high capacitance of $145\;nFcm^{-2}$ during and after 10s bending cycles with a small curvature radius of 7.5 mm. This film was optically transparent. Furthermore, the flexible, pentacene-based, organic thin-film transistors (OTFTs) fabricated on the polyethersulphone substrate at room temperature using a BNRT-$O_2$ film as a gate insulator exhibited a promising device performance with a high field effect mobility of $0.5\;cm^2V^{-1}s^{-1}$, an on/off current modulation of $10^5$ and a small subthreshold slope of $0.2\;Vdecade^{-1}$ under a low operating voltage of -5 V. This device also maintained a high carrier mobility of $0.45\;cm^2V^{-1}s^{-1}$ during the bending with a small curvature radius of 9 mm. Therefore, the BNRT-$O_2$ film is considered a promising material for the gate insulator of the flexible, pentacene-based OTFT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.356-356
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• 2007

Plasma immersion ion beam deposition (PIIBD) technique is a cost-effective process for the deposition of diamond like carbon thin film, the possible solid lubricant on large surface and a complex shape. We used PIIB process for the preparation of DLC thin film on $Al_2O_3$ with deposition conditions of deposition temperature range $200^{\circ}C$, working gas pressure of 1.310-1Pa. DLC thin films were coated by $C_2H_2$ ion beam deposition on $Al_2O_3$ after the ion bombardment of SiH4 as the bonding layer. Energetic bombardment of $C_2H_2$ ions during the DLC deposition to ceramic materials generated mixed layers at the DLC-Si interface which enhanced the interface to be highly bonded. Wear test showed that the low coefficient of friction of around 0.05 with normal load 2.9N and proved the advantage of the low energy ion bombardment in PIIBD process which improved the tribological properties of DLC thin film coated alumina ceramic. Furthermore, PIIBD was recognized as a useful surface modification technique for the deposition of DLC thin film on the irregular shape components, such as molds, and for the improvement of wear and adhesion problems of the DLC thin film, high temperature solid lubricant.