• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.68-69
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• 2005

BTO ($BaTiO_3$) thin film is one of the high dielectric materials for high-density dynamic random access memories (DRAMs) due to its relatively high dielectric constant. It is generally known that BTO film is difficult to be etched by plasma etching, but high etch rate with good selectivity to pattern mask was required. The problem of sidewall angle also still remained to be solved in plasma etching of BTO thin film. In this study, we first examined the patterning possibility of BTO film by chemical mechanical polishing (CMP) process instead of plasma etching. The sputtered BTO film on TEOS film as a stopper layer was polished by CMP process with the self-developed $BaTiO_3$- and $TiO_2$-mixed abrasives slurries (MAS), respectively. The removal rate of BTO thin film using the$ BaTiO_3$-mixed abrasive slurry ($BaTiO_3$-MAS) was higher than that using the $TiO_2$-mixed abrasive slurry ($TiO_2$-MAS) in the same concentrations. The maximum removal rate of BTO thin film was 848 nm/min with an addition of $BaTiO_3$ abrasive at the concentration of 3 wt%. The sufficient within-wafer non-uniformity (WIWNU%)below 5% was obtained in each abrasive at all concentrations. The surface morphology of polished BTO thin film was investigated by atomic force microscopy (AFM).

• Journal of Biomedical Engineering Research
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• v.6 no.1
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• pp.37-46
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• 1985

Development of a dental Ni-Cr alloy system for porcelain veneering crown and bridge was studied in this research. The principles of alloy design were a) It should not contain toxic beryllium. b) It should have low melting Point. c) It should be easily ground and polished. d) It should possess an adequate strength to resist the deformational force In the mouth. e) It should be bondable Ivith porcelain by chemically. After investigating the effect of minor elements such as boron and rare earth metals on the mechanical properties of the Ni-Cr alloy system, the compromised ideal composition for dental use was determined. The composition was l9.6%, Cr, 5.6% Mo, 3.4% Si, 1, 0% Fe, 0.01% Ti, 0.5-1.0% B, 0.2-0.6% misch metal, balance Ni. To compare the performance of experimental alloy with commercially available alloys, the properties such as strength, melting point, and bond strength were measured. The results Ivere as follows: a) Boron increases the strength of the alloy but reduces the elongation. b) Misch metal increases the strength when the boron content is low, but does not increase the strength when boron content is high. And it reduces the elongation drastically, c) Mechanical strength of the experimental alloy was not superior to commercially available Be containing alloy, but handling performance such as castability, ease of granting and polishing, and cuttability were superior to the Be containing alloy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.171-175
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• 2001

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectrics and metal, which can apply to employed in integrated circuits for sub-micron technology. Despite the increased use of CMP process, it is difficult to accomplish the global planarization of free-defects in inter level dielectrics and metal. Especially, defects like (micro-scratch) lead to severe circuit failure, and affects yield. Current conditioning method - bladder type, orbital pad motion - usually provides unsuitable pad profile during ex-situ conditioning near the end of pad life. Since much of the pad wear occurs by the mechanism of bladder tripe conditioning and its orbital motion without rotation, we need to implement new ex-situ conditioner which can prevent abnormal regional force on pad caused by bladder-type and also need to rotate the pad during conditioning. Another important study of ADPC is related to the orbital scratch of which source is assumed as diamond grit dropped from the strip during ex-situ conditioning. Scratch from diamond grit damaged wafer severely so usual1y scraped. Figure 1 shows the typical shape of scratch damaged from diamond. We suspected that intensive forces to the edge area of bladder type stripper accelerated the drop of Diamond grit during conditioning, so new designed Flat stripper was introduced.

• Korean Security Journal
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• no.25
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• pp.131-146
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• 2010

Purpose of this research about reduction the scholastic systematic triangular position of the security guard martial art which repeats a development is insufficient with demand of the while society to recognize and for the philosophic value research of security guard martial art composition principle puts out with the one method and from the reporter to search the aesthetics which appears does. In order to attain the goal of the research which sees the literature which relates with an security guard martial art widly, was an investigation and observed the aesthetics from concept and martial art of aesthetics and this the technical free use ability from actual site of the technical find which leads the practice voluntary repetition practice of security guard martial art with character and the body guard aesthetic integral part experience possibly did, there being will be able to acquire an aesthetic inspiration, confirmed. So the security guard martial art follows the composition principle of maximization central attitude and shock point breath control and mental intensive etc. of reinforcement of direction shock of relativity redundancy mental moral culture body agreement characteristic force and relaxation force and is completed and will be able to embody an aesthetic value with aesthetic elements of technical polishing process inside goes about reduction.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.545-553
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• 2003

To achieve good dentin bonding, we must obtain proper wet dentin surface. The purpose of this study was to compare dentin surface according to different wetness degree by AFM image as studying how to obtaining proper wet dentin surface. Intact recently extracted primary teeth were used in the study. The extracted teeth were stored in distilled water at $4^{\circ}C$ until prepared. The teeth were used to prepare 1mm thick dentin disks with exposed surfaces parallel to the occlusal surfaces. The surface of the dentin were polished with polishing disk. The sample were ultrasonically cleaned with distilled water. The sample of each group were treated by different ways. We compared dentin surface of each group by AFM image. From the experiment, the following results were obtained. 1. Acid etching in the dentin surface of primary teeth, resulted in the removal of the smear layer, which opened dentinal tubules, caused the demineralization of peritubular and intertubular dentin, and exposed a collagen-rich transition zone. 2. If the etched dentin was so dehydrated, the intertubular dentin surfaces deceased in height and the diameters of the dentinal tubules decreased slightly. 3. In the group dried with compressed air for 20 seconds at 2 cm, the dentin surfaces were too excessive dried and dehydrated. 4. In the group dried with compressed air for 3 seconds at 2 cm, dry cotton, wet cotton, microbrush and absorbent tissue paper, the dentin surfaces were properly wet.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.276-280
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• 2010

Copper(Cu) as an interconnecting metal layer can replace aluminum (Al) in IC fabrication since Cu has low electrical resistivity, showing high immunity to electromigration compared to Al. However, it is very difficult for copper to be patterned by the dry etching processes. The chemical mechanical polishing (CMP) process has been introduced and widely used as the mainstream patterning technique for Cu in the fabrication of deep submicron integrated circuits in light of its capability to reduce surface roughness. But this process leaves a large amount of residues on the wafer surface, which must be removed by the post-CMP cleaning processes. Copper corrosion is one of the critical issues for the copper metallization process. Thus, in order to understand the copper corrosion problems in post-CMP cleaning solutions and study the effects of DC biases and post-CMP cleaning solution concentrations on the Cu film, a constant voltage was supplied at various concentrations, and then the output currents were measured and recorded with time. Most of the cases, the current was steadily decreased (i.e. resistance was increased by the oxidation). In the lowest concentration case only, the current was steadily increased with the scarce fluctuations. The higher the constant supplied DC voltage values, the higher the initial output current and the saturated current values. However the time to be taken for it to be saturated was almost the same for all the DC supplied voltage values. It was indicated that the oxide formation was not dependent on the supplied voltage values and 1 V was more than enough to form the oxide. With applied voltages lower than 3 V combined with any concentration, the perforation through the oxide film rarely took place due to the insufficient driving force (voltage) and the copper oxidation ceased. However, with the voltage higher than 3 V, the copper ions were started to diffuse out through the oxide film and thus made pores to be formed on the oxide surface, causing the current to increase and a part of the exposed copper film inside the pores gets back to be oxidized and the rest of it was remained without any further oxidation, causing the current back to decrease a little bit. With increasing the applied DC bias value, the shorter time to be taken for copper ions to be diffused out through the copper oxide film. From the discussions above, it could be concluded that the oxide film was formed and grown by the copper ion diffusion first and then the reaction with any oxidant in the post-CMP cleaning solution.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.59-66
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• 2004

This paper presents a novel fabrication process for a tapered hollow metallic microneedle array using backside exposure of SU-8, and analytic solutions of critical buckling of a tapered hollow microneedle. An SU-8 meta was formed on a Pyrex glass substrate and another SU-8 layer, which was spun on top of the SU-8 mesa, was exposed through the backside of the glass substrate. An array of SU-8 tapered pillar structures. with angles in the range of $3.1^{\circ}{\sim}5^{\circ}$ was formed on top of the SU-8 mesa. Conformal electrodeposition of metal was carried out followed by a mechanical polishing using a pianarizing polymeric layer. All organic layers were then removed to create a metallic hollow microneedle array with a fluidic reservoir on the backside. Both $200{\mu}m\;and\;400{\mu}m$ tall, 10 by 10 arrays of metallic microneedles with inner diameters of the tip in the range of $33.6{\sim}101\;{\mu}m$ and wall thickness of $10{\mu}m\;-\;20{\mu}m$ were fabricated. Analytic solutions of the critical buckling of arbitrary-angled truncated cone-shaped columns are also presented. It was found that a single $400{\mu}m$ tall hollow cylindrical microneedle made of electroplated nickel with a wall thickness of $20{\mu}m$, a tapered angle of $3.08^{\circ}$ and a tip inner diameter of $33.6{\mu}m$ has a critical buckling force of 1.8 N. This analytic solution can be used for square or rectangular cross-sectioned column structures with proper modifications.