• Title/Summary/Keyword: Adhesion Properties

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Role of oxidant on polishing selectivity in the chemical mechanical planarization of W/Ti/TiN layers (W/Ti/TiN막의 연마 선택비 개선을 위한 산화제의 역할)

  • Lee, Kyoung-Jin;Seo, Yong-Jin;Park, Chang-Jun;Kim, Gi-Uk;Kim, Sang-Yong;Lee, Woo-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05c
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    • pp.33-36
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    • 2003
  • Tungsten is widely used as a plug for the multi-level interconnection structures. However, due to the poor adhesive properties of tungsten (W) on $SiO_2$ layer, the Ti/TiN barrier layer is usually deposited onto $SiO_2$ for increasing adhesion ability with W film. Generally, for the W-CMP (chemical mechanical polishing) process, the passivation layer on the tungsten surface during CMP plays an important role. In this paper, the effect of oxidants controlling the polishing selectivity of W/Ti/TiN layer were investigated. The alumina $(Al_2O_3)$ abrasive containing slurry with 5 % $H_2O_2$ as the oxidizer, was studied. As our preliminary experimental results, very low removal rates were observed for the case of no-oxidant slurry. This low removal rate is only due to the mechanical abrasive force. However, for Ti and TiN with 5 % $H_2O_2$ oxidizer, different removal rate was observed. The removal mechanism of Ti during CMP is mainly due to mechanical abrasive, whereas for TiN, it is due to the formation of metastable soluble peroxide complex.

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Hydrophobic Properties of PTFE Film Deposited on Glass Surface Etched by Ar-plasma (아르곤 플라즈마를 이용하여 유리기판에 증착된 PTFE 박막의 초친수 특성 연구)

  • Rhee, Byung Roh;Bae, Kang;Kim, Hwa-Min
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.8
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    • pp.516-521
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    • 2014
  • An excellent hydrophobic surface has a high contact angle over 147 degree and the contact angle hysteresis below $5^0$ was produced by using roughness combined with hydrophobic PTFE coatings, which were also confirmed to exhibit an extreme adhesion to glass substrate. To form the rough surface, the glass was etched by Ar-plasma. A very thin PTFE film was coated on the plasma etched glass surface. Roughness factors before or after PTFE coating on the plasma etched glass surface, based on Wensel's model were calculated, which agrees well with the dependence of the contact angle on the roughness factor is predicted by Wensel's model. The PTFE films deposited on glass by using a conventional rf-magnetron sputtering. The glass substrates were etched Ar-plasma prior to the deposition of PTFE. Their hydrophobicities are investigated for application as a anti-fouling coating layer on the screen of displays. It is found that the hydrophobicity of PTFE films mainly depends on the sputtering conditions, such as rf-power, Ar gas content introduced during deposition. These conditions are closely related to the deposition rate or thickness of PTFE film. Thus, it is also found that the deposition rate or the film thickness affects sensitively the geometrical morphology formed on surface of the rf-sputtered PTFE films. In particular, 1,950-nm-thick PTFE films deposited for 30 minute by rf-power 50 watt under Ar gas content of 20 sccm shows a very excellent optical transmittance and a good anti-fouling property and a good durability.

A Study on the Quality Improvement of Recycled Coarse Aggregate by High Speed Rotating Grinder (고속회전형 마쇄기술을 통한 순환골재 품질향상에 관한 연구)

  • Lee, Ki-Won;Yeo, Woon-Ho
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.341-348
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    • 2019
  • In this study, we analyzed the problems of existing construction waste shredding technology to diagnose the problems of low quality recycled aggregates and to develop a new mortar peeling technique to produce high-quality recycled coarse aggregate for concrete. The purpose of this study is to verify the effectiveness of mortar peeling technique by doing simulation prior to on-site application and to check the quality properties of recycled coarse aggregate produced by applying a mortar peeling technique. We manufactured and installed High speed Rotating Grinder on-site and analyzed the correlation between mortar adhesion amount, dry density and water absorption rate of recycled coarse aggregate.

MICROSTRUCTURE AND TRIBOLOGY OF $TiB_2$ AND $TiB_2$-TiN DOUBLE-LAYER COATINGS

  • Yang, Yunjie;Chen, Lizhi;Zheng, Zhihong;Wang, Xi;Liu, Xianghuai
    • Journal of the Korean Vacuum Society
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    • v.4 no.S2
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    • pp.40-48
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    • 1995
  • $TiB_2$-TiN double-layer coating have been prepared by ion beam enhanced deposition. AES, XRD, TEM and HRTEM were employed to characterize the $TiB_2$ layer. The microhardness of the coatings was evaluated by an ultra low-load microhardness indenter system, and the tribological behavior was examined by a ball-on-disc tribology wear tester. It was found that in a single titanium diboride layer, the composition is uniform along the depth of the film, and it is mainly composed of nanocrystalline $TiB_2$ with hexagonal structure, which resulted from the ion bombardment during the film growth. The hardness of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of 39 Gpa at ion energy of 85 keV. The tribological property of the TiB2 films is also improved by higher energy of 85keV. The tribological property of the $TiB_2$ films is also improved by higher energy ion beam bombardment. There is no major disparity in the mechanical properties of double-layer $TiB_2$/TiN coatings and TiN/$TiB_2$ coatings. Both show an improved wear resistance compared with single-layer $TiB_2$ films. The adhesion of double-layer coatings is also superior to that of single-layer films.

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Effects of $N_2/H_2$ plasma treatments on enhancement of neuronal cell affinity on single-walled carbon nanotube paper scaffolds

  • Yoon, Ok-Ja;Lee, Hyun-Jung;Jang, Yeong-Mi;Kim, Hyun-Woo;Lee, Won-Bok;Kim, Sung-Su;Lee, Nae-Eung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.393-393
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    • 2010
  • The biocompatibility of materials used for biomedical applications depends on chemical composition, mechanical stiffness, surface energy, and roughness. The plasma treatment and etching process is a very important technology in the biomedical fields due to possibility of controlling the surface chemistry and properties of materials. In this work, $N_2/H_2$ plasma were treated on single-walled carbon nanotubes (SWCNTs) paper and characterization of treated SWCNTs paper was carried out. Also we investigated neurite outgrowth from SH-SY5Y on treated SWCNTs paper. The results indicated that $N_2/H_2$ plasma-modified SWCNTs paper enhanced neuronal cell adhesion, viability, neurite outgrowth and branching in vitro and exerted a positive role on the health of neural cells.

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Selective Growth of Nanosphere Assisted Vertical Zinc Oxide Nanowires with Hydrothermal Method

  • Lee, Jin-Su;Nam, Sang-Hun;Yu, Jung-Hun;Yun, Sang-Ho;Boo, Jin-Hyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.252.2-252.2
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    • 2013
  • ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

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Anticariogenic Properties of the Extract of Saururus chinensis (삼백초 추출물의 항치아우식 효과)

  • Lee, Da-Hong;Yu, Hyeon-Hee;Jung, Su-Young;Moon, Hae-Dalma;Park, Ki-Bong;Cho, Soo-Min;Jeon, Byung-Hun;Kim, In-Sook;You, Yong-Ouk
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.21 no.3
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    • pp.647-651
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    • 2007
  • It has been well established that S. mutans is the major etiological agent in dental caries, one of the most common oral diseases worldwide. The present study was designed to investigate the effect of Saururus chinensis (S. chinensis) ethanol extracts on the growth, acid production, biofilm formation, adhesion, and insoluble glucan synthesis of S. mutans. The ethanol extracts of S. chinensis showed concentration dependent inhibitory activity against the growth and acid production of S. mutans, and produced significant inhibition at the concentration of 0.025, 0.05, 0.1, 0.2 and 0.4 mg/ml compared to the control group. The extracts markedly inhibited S. mutans adherence to HA treated with saliva, and cell adherence was repressed by more than 80% at the concentration of 0.05 mg/ml and complete inhibition was observed at the concentration of 0.4 mg/ml. On the activity of glucosyltransferase which synthesizes water insoluble glucan form sucrose, ethanol extract of S. chinensis showed more than 10% inhibition over the concentration of 0.025 mg/ml. The synthesis of insoluble glucan was decreased in the presence of 0.025 ${\sim}$ 0.4 mg/ml of the ethanol extract of S. chinensis. Our research strongly suggested S. chinensis was a promising natural product for the prevention of dental caries.

Friction Behavior of High Velocity Oxygen Fuel (HVOF) Thermal Spray Coating Layer of Nano WC-Co Powder

  • Cho, T.Y.;Yoon, J.H.;Kim, K.S.;Fang, W.;Joo, Y.K.;Song, K.O.;Youn, S.J.;Hwang, S.Y.;Chun, H.G.
    • Journal of the Korean institute of surface engineering
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    • v.40 no.4
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    • pp.170-174
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    • 2007
  • High Velocity Oxygen Fuel (HVOF) thermal spray coating of nano size WC-Co powder (nWC-Co) has been studied as one of the most promising candidate for the possible replacement of the traditional hard plating in some area which causes environmental and health problems. nWC-Co powder was coated on Inconel 718 substrates by HVOF technique. The optimal coating process obtained from the best surface properties such as hardness and porosity is the process of oxygen flow rate (FR) 38 FMR, hydrogen FR 57 FMR and feed rate 35 g/min at spray distance 6 inch for both surface temperature $25^{\circ}C\;and\;500^{\circ}C$. In coating process a small portion of hard WC decomposes to less hard $W_2C$, W and C at the temperature higher than its decomposition temperature $1,250^{\circ}C$ resulting in hardness decrease and porosity increase. Friction coefficient increases with increasing coating surface temperature from 0.55-0.64 at $25^{\circ}C$ to 0.65-0.76 at $500^{\circ}C$ due to the increase of adhesion between coating and counter sliding surface. Hardness of nWC-Co is higher or comparable to those of other hard coatings, such as $Al_2O_3,\;Cr,\;Cr_2O_3$ and HVOF Tribaloy 400 (T400). This shows that nWC-Co is recommendable for durability improvement coating on machine components such as high speed spindle.

Polydopamine Coating Behaviors on the Acrylic Acid Grafted-Nanofibers (아크릴산이 그라프트된 나노섬유에서의 폴리도파민 코팅)

  • Shin, Young Min;Kim, Woo-Jin;Park, Jong-Seok;Gwon, Hui-Jeong;Nho, Young-Chang;Lim, Youn-Mook
    • Journal of Radiation Industry
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    • v.5 no.4
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    • pp.371-376
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    • 2011
  • The surface property of the materials used in tissue engineering application has been essential to regulate cellular behaviors by directing their adhesion on the materials. To modulate surface property of the synthetic biodegradable materials, a variety of surface modification techniques have used to introduced surface functional groups or bioactive molecules, recently polydopamine coating method have been introduce as a facile modification method which can be coated on various materials such as polymers, metals, and ceramics regardless of their surface property. However, there are no reports about the degree of polydopamine coating on the materials with different hydrophilicity. In the present study, we prepared acrylic acid grafted nanofibrous meshes using electron-beam irradiation, and then coated meshes with polydopamine. Polydopamine successfully coated on the all meshes, both properties of acrylic acid and polydopamine were detected on the meshes. In addition, the degree of polydopamine deposition on the materials has been altered according to surface hydrophilicity, which was approximately 8-times greater than those on the non-modified materials. In conclusion, dual effect from the acrylic acid grafting and polydopamine may give a chance as a alternative tool in tissue engineering application.

Improved Biocompatibility of Intra-Arterial Poly-L-Lactic Acid Stent by Tantalum Ion Implantation : 3-Month Results in a Swine Model

  • Kim, Kangmin;Park, Suhyung;Park, Jeong Hwan;Cho, Won-Sang;Kim, Hyoun-Ee;Lee, Sung-Mi;Kim, Jeong Eun;Kang, Hyun-Seung;Jang, Tae-Sik
    • Journal of Korean Neurosurgical Society
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    • v.64 no.6
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    • pp.853-863
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    • 2021
  • Objective : Biodegradable poly-L-lactic acid (PLLA) with a highly biocompatible surface via tantalum (Ta) ion implantation can be an innovative solution for the problems associated with current biodegradable stents. The purpose of this study is to develop a Taimplanted PLLA stent for clinical use and to investigate its biological performance capabilities. Methods : A series of in vitro and in vivo tests were used to assess the biological performance of bare and Ta-implanted PLLA stents. The re-endothelialization ability and thrombogenicity were examined through in vitro endothelial cell and platelet adhesion tests. An in vivo swine model was used to evaluate the effects of Ta ion implantation on subacute restenosis and thrombosis. Angiographic and histologic evaluations were conducted at one, two and three months post-treatment. Results : The Ta-implanted PLLA stent was successfully fabricated, exhibiting a smooth surface morphology and modified layer integration. After Ta ion implantation, the surface properties were more favorable for rapid endothelialization and for less platelet attachment compared to the bare PLLA stent. In an in vivo animal test, follow-up angiography showed no evidence of in-stent stenosis in either group. In a microscopic histologic examination, luminal thrombus formation was significantly suppressed in the Ta-implanted PLLA stent group according to the 2-month follow-up assessment (21.2% vs. 63.9%, p=0.005). Cells positive for CD 68, a marker for the monocyte lineage, were less frequently identified around the Ta-implanted PLLA stent in the 1-month follow-up assessments. Conclusion : The use of a Ta-implanted PLLA stent appears to promote re-endothelialization and anti-thrombogenicity.