• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.254-254
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• 2011

The memories with nano-particles are very attractive because they are promising candidates for low operating voltage, long retention time and fast program/erase speed. In recent, various nano-floating gate memories with metal-oxide nanocrystals embedded in organic and inorganic layers have been reported. Because of the carrier generation in semiconductor, induced photon pulse enhanced the program/erase speed of memory device. We studied photo-induced electrical properties of these metal-oxide nanocrystal memory devices. At first, 2~10-nm-thick Sn and In metals were deposited by using thermal evaporation onto Si wafer including a channel with $n^+$ poly-Si source/drain in which the length and width are 10 ${\mu}m$ each. Then, a poly-amic-acid (PAA) was spin coated on the deposited Sn film. The PAA precursor used in this study was prepared by dissolving biphenyl-tetracarboxylic dianhydride-phenylene diamine (BPDA-PDA) commercial polyamic acid in N-methyl-2-pyrrolidon (NMP). Then the samples were cured at 400$^{\circ}C$ for 1 hour in N atmosphere after drying at 135$^{\circ}C$ for 30 min through rapid thermal annealing. The deposition of aluminum layer with thickness of 200 nm was followed by using a thermal evaporator, and then the gate electrode was defined by photolithography and etching. The electrical properties were measured at room temperature using an HP4156a precision semiconductor parameter analyzer and an Agilent 81101A pulse generator. Also, the optical pulse for the study on photo-induced electrical properties was applied by Xeon lamp light source and a monochromator system.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.686-691
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• 2008

There are no many research reports on the preparation of ZnO by electrochemical oxidation since the zinc oxide is very easily dissolved in an acidic or basic environment, even though zinc oxides have attracted many attentions because of their optical/electrical properties. In this paper, we describe the fabrication of self-ordered stripes of ZnO by anodization of Zn in an ethanolic sulfuric acid. The formation of stripes of ZnO originating from Zn is attributed to water-selective dissolution of ZnO during anodization. We study in detail the effects of concentration of $H_2SO_4$, applied potential, anodization time, and addition of a small amount of water on the fabrication of stripes of ZnO. Mechanisms for the fabrication of ZnO stripes are discussed in terms of the above-mentioned effects.

• The Journal of Advanced Prosthodontics
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• v.2 no.1
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• pp.18-24
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• 2010

PURPOSE. The aim of this pilot study was to investigate the effect of etched microgrooves on the hydrophilicity of Ti and osteoblast responses. MATERIAL AND METHODS. Microgrooves were applied on Ti to have 15 and $60{\mu}m$ width, and 3.5 and $10{\mu}m$ depth by photolithography, respectively. Further acid etching was applied to create Ti surfaces with etched microgrooves. Both smooth- and acid-etched Ti were used as the controls. The hydrophilicity of Ti was analyzed by determining contact angles. Cell proliferation and osteogenic activity of MC3T3 mouse preosteoblasts were analyzed by bromodeoxyuridine assay and alkaline phosphatase (ALP) activity test, respectively. One-way ANOVA, Pearson's correlation analysis and multiple regression analysis were used for statistics. RESULTS. Etched microgrooves significantly increased the hydrophilicity of Ti compared to the smooth Ti. $60{\mu}m$-wide etched microgrooves significantly enhanced cell proliferation, whereas the osteogenic activity showed statistically non-significant differences between groups. Result of the osteogenic activity significantly correlated with those of hydrophilicity and cell proliferation. Hydrophilicity was determined to be an influential factor on osteogenic activity. CONCLUSION. This study indicates that increase in hydrophilicity of Ti caused by etched microgrooves acts as an influential factor on osteogenic activity. However, statistically non-significant increase in the ALP activity suggests further investigation.

• Korean Journal of Materials Research
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• v.16 no.12
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• pp.731-738
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• 2006

It is seriously considered using Al CMP (chemical mechanical planarization) process for the next generation 45 nm Al wiring process. Al CMP is known that it has a possibility of reducing process time and steps comparing with conventional RIE (reactive ion etching) method. Also, it is more cost effective than Cu CMP and better electrical conductivity than W via process. In this study, we investigated 4 different kinds of slurries based on abrasives for reducing scratches which contributed to make defects in Al CMP. The abrasives used in this experiment were alumina, fumed silica, alkaline colloidal silica, and acidic colloidal silica. Al CMP process was conducted as functions of abrasive contents, $H_3PO_4$ contents and pressures to find out the optimized parameters and conditions. Al removal rates were slowed over 2 wt% of slurry contents in all types of slurries. The removal rates of alumina and fumed silica slurries were increased by phosphoric acid but acidic colloidal slurry was slightly increased at 2 vol% and soon decreased. The excessive addition of phosphoric acid affected the particle size distributions and increased scratches. Polishing pressure increased not only the removal rate but also the surface scratches. Acidic colloidal silica slurry showed the highest removal rate and the lowest roughness values among the 4 different slurry types.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.335-341
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• 2012

Recently, the demand for the miniaturization of printed circuit boards has been increasing, as electronic devices have been sharply downsized. Conventional multi-layered PCBs are limited in terms their use with higher packaging densities. Therefore, a build-up process has been adopted as a new multi-layered PCB manufacturing process. In this process, via-holes are used to connect each conductive layer. After the connection of the interlayers created by electro copper plating, the via-holes are filled with a conductive paste. In this study, a desmear treatment, electroless plating and electroplating were carried out to investigate the optimum processing conditions for Cu via filling on a PCB. The desmear treatment involved swelling, etching, reduction, and an acid dip. A seed layer was formed on the via surface by electroless Cu plating. For Cu via filling, the electroplating of Cu from an acid sulfate bath containing typical additives such as PEG(polyethylene glycol), chloride ions, bis-(3-sodiumsulfopropyl disulfide) (SPS), and Janus Green B(JGB) was carried out. The desmear treatment clearly removes laser drilling residue and improves the surface roughness, which is necessary to ensure good adhesion of the Cu. A homogeneous and thick Cu seed layer was deposited on the samples after the desmear treatment. The 2,2'-Dipyridyl additive significantly improves the seed layer quality. SPS, PEG, and JGB additives are necessary to ensure defect-free bottom-up super filling.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.230-234
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• 2011

In this work, the primary material for a single layered hardmask which can afford a spin-on process was prepared by the minture of organic and inorganic sources. The preparation of hybrid polymer was attempted by esterification from silanol terminated siloxane compounds and acetonide-2,2-bis(methoxy)propionic acid. The optical, thermal and morphological properties of the test hardmask film was examined in terms of cross-linking agent and additives. In addition, the etch rate of hardmask film and photo resist layer were compared. The hybrid polymer prepared from organic and inorganic materials was found to be useful for hardmask film to form the nano-patterns.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.148-156
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• 2008

Statement of problems: Self-etch adhesives exhibit some clinical benefits such as ease of manipulation and reduced technique-sensitivity. Nevertheless, some concern remains regarding the bonding effectiveness of self-etch adhesives to enamel, in particular when so-called 'mild' self-etch adhesives are employed. This study compared the microtensile bond strengths to ground enamel of the two-step self-etch adhesive Clearfil SE Bond (Kuraray) to the three-step etch-and- rinse adhesive Scotchbond Multi-Purpose (3M ESPE) and the one-step self-etch adhesive iBond (Heraeus Kulzer). Purpose: The purpose of this study was to determine the effect of a preceding phosphoric acid conditioning step on the bonding effectiveness of a two-step self-etch adhesive to ground enamel. Material and methods: The two-step self-etch adhesive Clearfil SE Bond non-etch group, Clearfil SE Bond etch group with prior 35% phosphoric acid etching, and the one-step self-etch adhesive iBond group were used as experimental groups. The three-step etch-and-rinse adhesive Scotchbond Multi-Purpose was used as a control group. The facial surfaces of bovine incisors were divided in four equal parts cruciformly, and randomly distributed into each group. The facial surface of each incisor was ground with 800-grit silicon carbide paper. Each adhesive group was applied according to the manufacturer's instructions to ground enamel, after which the surface was built up using Light-Core (Bisco). After storage in distilled water at $37^{\circ}C$ for 1 week, the restored teeth were sectioned into enamel beams approximately 0.8*0.8mm in cross section using a low speed precision diamond saw (TOPMET Metsaw-LS). After storage in distilled water at $37^{\circ}C$ for 1 month, 3 months, microtensile bond strength evaluations were performed using microspecimens. The microtensile bond strength (MPa) was derived by dividing the imposed force (N) at time of fracture by the bond area ($mm^2$). The mode of failure at the interface was determined with a microscope (Microscope-B nocular, Nikon). The data of microtensile bond strength were statistically analyzed using a one-way ANOVA, followed by Least Significant Difference Post Hoc Test at a significance level of 5%. Results: The mean microtensile bond strength after 1 month of storage showed no statistically significant difference between all adhesive groups (P>0.05). After 3 months of storage, adhesion to ground enamel of iBond was not significantly different from Clearfil SE Bond etch (P>>0.05), while Clearfil SE Bond non-etch and Scotchbond Multi-Purpose demonstrated significantly lower bond strengths (P<0.05), with no significant differences between the two adhesives. Conclusion: In this study the microtensile bond strength to ground enamel of two-step self-etch adhesive Clearfil SE Bond was not significantly different from three-step etch-and-rinse adhesive Scotchbond Multi-Purpose, and prior etching with 35% phosphoric acid significantly increased the bonding effectiveness of Clearfil SE Bond to enamel at 3 months.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.131-139
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• 2020

PURPOSE. The purpose of this study is to evaluate the repair bond strength of a nanohybrid resin composite to three CAD/CAM blocks using different intraoral ceramic repair systems. MATERIALS AND METHODS. Three CAD/CAM blocks (Lava Ultimate, Cerasmart, and Vitablocks Mark II) were selected for the study. Thirty-two specimens were fabricated from each block. Specimens were randomly divided into eight groups for the following different intraoral repair systems: Group 1: control group (no treatment); Group 2: 34.5% phosphoric acid etching; Group 3: CoJet System; Group 4: Z-Prime Plus System; Group 5: GC Repair System; Group 6: Cimara System; Group 7: Porcelain Repair System; and Group 8: Clearfil Repair System. Then, nanohybrid resin composite (Tetric Evo Ceram) was packed onto treated blocks surfaces. The specimens were thermocycled before application of repair systems and after application of composite resin. After second thermal cycling, blocks were cut into bars (1 × 1 × 12 ㎣) for microtensile bond strength tests. Data were analyzed using two-way ANOVA and Tukey's HSD test (α=.05). RESULTS. Cimara System, Porcelain Repair, and Clearfil Repair systems significantly increased the bond strength of nanohybrid resin composite to all CAD/CAM blocks when compared with the other tested repair systems (P<.05). In terms of CAD/CAM blocks, the lowest values were observed in Vitablocks Mark II groups (P<.05). CONCLUSION. All repair systems used in the study exhibited clinically acceptable bond strength and can be recommended for clinical use.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.9
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• pp.423-430
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• 2002

The fabrication and experimentation of multi-channel electrodes which enable detecting and recording of multi-site neuronal signals have been investigated. A multi-channel electrode array was fabricated by depositing 2000${\AA}$ thick Au layer on the 1000${\AA}$ thick Ti adhesion layer on a glass wafer. The metal paths were patterned by wet etching and passivated by depositing a PECVD silicon nitride insulation layer to prevent signals from intermixing or cross-talking. After placing a thin slice of rat cerebellar granule cell in the culture ring located in central portion of the multi-channel electrode plate, a neuronal signal from an electrode which is in contact with the cerebellar granule cell has been detected. It was found that the electrode impedance ranges 200㏀∼1㏁ and the impedance is not changed by cleaning with nitric acid. Also, the impedance is inversely proportion to the exposed electrode area and the cross-talk is negligible when the electrode spacing is bigger than 600$\mu\textrm{m}$. The amplitude and frequency of the measured action potential were 38㎷ and 2㎑, which are typical values. From the experimental results, the fabricated multi-channel electrode array proved to be suitable for multi-site neuronal signal detection for the analysis of a complicated cell network.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.10
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• pp.1117-1124
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• 2012

This study was a preliminary study to investigate the influence of surface morphology and characteristics on the self-cleaning of substrates. PI film was treated by $O_2$ plasma to modify the surface; in addition, AFM and Fe-SEM were employed to examine the morphological changes induced on a PI film treated by $O_2$ plasma and surface energies calculated from measured contact angles between several solutions and PI film based on the geometric mean and a Lewis acid base method. The surface roughness of PI film treated by $O_2$ plasma increased with the duration of the $O_2$ plasma on PI film due to the increased surface etching. The contact angle of film treated by $O_2$ plasma decreased with the increased treatment time in water and surfactant solution; in addition, the surface energy increased with the increased treatment times largely attributed to the increased portion on the polar surface energy of PI film. The coefficient of the correlation between surface roughness and surface polarity such as contact angle and surface energy was below 0.35; however, it was over 0.99 for the contact angle and surface energy.