• 대한치과보철학회지
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• 제30권4호
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• pp.508-525
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• 1992

The purpose of this study was to evaluate the effect of some resistance form designs on the bond strength of resin-retained prosthesis. Six sub-groups are designed in natural teeth group and resin teeth group . The framework designs in natural teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) 45 degree lateral load with no groove 5) 45 degree lateral load with center groove 6) splint two teeth with no groove. The framework designs in resin teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) metal covered the 1/2 of distal surface 5) metal covered the 1/2 of mesial surface 6) metal extended over the 114 of buccal surface. Specimens were treated electrolytic etching by Oxy-Etch and cemented with Panavia EX. Failure load was measured by Instron. Another 30 specimens were carried out fatigue tests by MTS 810 fatigue testing machine for 5000 cycles at different load level. The following results were obtained from this study. 1. The failure load was significantly increased by resistance forms. 2. The failure load was not increased by increase of total surface area bonded with teeth. The distal surface area played an important role in failure load. 3. In 45 degree lateral load group, the failure load was decreased significantly than that of in vertical load group. 4. Bond failure modes between static test and fatigue test exhibited no differences.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2410-2412
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• 2005

In this study, two types of PS substrate were fabricated for sensing of chemical and biological substances. For sensing of the humidity and chemical analyzes such as $CH_3OH$ or $C_2H_5OH$, PS layers are prepared by photoelectrochemical etching of silicon wafer in aqueous hydrofluoric acid solution. To evaluate their sensitivity, we measured the resistance variation of the PS diaphragm. As the amplitude of applied voltage increases from 2 to 6Vpp at constant frequency of 5kHz, the resistance variation for humidity sensor rises from 376.3 to $784.8{\Omega}$/%RH. And the sensitivities for $CH_3OH$ and $C_2H_5OH$ were 0.068 uA/% and 0.212 uA/%, respectively. For biological sensing application, amperometric urea sensors were fabricated based on porous silicon(PS), and planar silicon(PLS) electrode substrates by the electrochemical methods. Pt thin film was sputtered on these substrates which were previously formed by electrochemical anodization. Poly (3-methylthiophene) (P3MT) were used for electron transfer matrix between urease(Urs) and the electrode phase, and Urs also was by electrochemically immobilized. Effective working area of these electrodes was determined for the first time by using $Fe(CN)_6^{3-}/Fe(CN)_6^{4-}$ redox couple in which nearly reversible cyclic voltammograms were obtained. The $i_p$ vs $v^{1/2}$ plots show that effective working electrode area of the PS-based Pt thin film electrode was 1.6 times larger than the PLS-based one and we can readily expect the enlarged surface area of PS electrode would result in increased sensitivity by ca. 1.6 times. Actually, amperometric sensitivity of the Urs/P3MT/Pt/PS electrode was ca 0.91uA/$mM{\cdot}cm^2$, and that of the Urs/P3MT/Pt/PLS electrode was ca. 0.91uA/$mM{\cdot}cm^2$ in a linear range of 1mmol/L to 100mmol/L urea concentrations

• 센서학회지
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• 제22권5호
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• pp.333-337
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• 2013

This study proposes a simply fabricated micro stator for higher output power than previously reported micro stators. The stator has been fabricated by inserting enamel coil in silicon mold formed by micro etching process. The most merits of the proposed micro stator are the simple fabrication process and high output power. Previously reported micro stators have high resistance because the micro coil is fabricated by relatively thin-film-based deposition process such as sputtering and electroplating. In addition, the previously reported micro coil has many electrical contact points for forming the coil structure. These characteristics of the micro stator can lead to low performance in output power. However, the proposed micro stator adopts commercially available enamel coil without any contact point. Therefore, the enamel coil of the proposed micro stator has low junction resistance due to the good electrical quality compared with the deposited or electroplated metal coil. Power generation tests were performed and the fabricated stator can produce 5.4 mW in 4000 RPM, $1{\Omega}$ and 0.3 mm gap. The proposed micro stator can produce larger output power than the previously reported stator spite of low RPM and the larger gap between the permanent magnet and the stator.

• 대한전자공학회논문지SD
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• 제47권11호
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• pp.1-5
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• 2010

본 논문에서는 외팔보 배열 구조를 가지는 MEMS 테스트 소켓을 SOI 웨이퍼를 이용하여 개발하였다. 외팔보는 연결부분의 기계적 취약점을 보완하기 위해 모서리가 둥근 형태를 가지고 있다. 측정에 사용 된 BGA IC 패키지는 볼 수 121개, 피치가 $650{\mu}m$, 볼 직경 $300{\mu}m$, 높이 $200{\mu}m$ 을 가지고 있다. 제작된 외팔보는 길이 $350{\mu}m$, 최대 폭 $200{\mu}m$, 최소 폭 $100{\mu}m$, 두께가 $10{\mu}m$인 곡선 형태의 외팔보이다. MEMS 테스트 소켓은 lift-off 기술과 Deep RIE 기술 등의 미세전기기계시스템(MEMS) 기술로 제작되었다. MEMS 테스트 소켓은 간단한 구조와 낮은 제작비, 미세 피치, 높은 핀 수와 빠른 프로토타입을 제작할 수 있다는 장점이 있다. MEMS 테스트의 특성을 평가하기 위해 deflection에 따른 접촉힘과 금속과 팁 사이의 저항과 접촉저항을 측정하였다. 제작된 외팔보는 $90{\mu}m$ deflection에 1.3 gf의 접촉힘을 나타내었다. 신호경로저항은 $17{\Omega}$ 이하였고 접촉저항은 평균 $0.73{\Omega}$ 정도였다. 제작된 테스트 소켓은 향 후 BGA IC 패키지 테스트에 적용 가능 할 것이다.

• 공업화학
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• 제17권2호
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• pp.158-162
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• 2006

새로운 극자외선 리소그래피용 화학증폭형 레지스트의 매트릭스 수지로 poly[4-hydroxystyrene-co-2-(4-methoxybutyl)-2-adamantyl methacrylate]를 합성하고 평가하였다. 이 중합체로 제조된 레지스트로 KrF 엑시머 레이저 노광장비를 사용하여 선폭 120 nm (피치 240 nm)를 구현할 수 있었다. 극자외선 리소그래피 장비를 이용하여 평가한 결과 선폭 50 nm (피치 180 nm)의 포지형 패턴을 얻었다. $CF_{4}$ 플라즈마를 이용한 건식에칭내성 평가 결과 기존 원자외선 레지스트용 매트릭스 수지인 poly(4-hydroxystyrene)보다 약 10% 향상되었다.

• 전자공학회논문지D
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• 제35D권8호
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• pp.8-14
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• 1998

A new process is developed to improve the electrical characteristics of high .beta. and low saturation voltage power transistor for lamp solenoid driver application. To prevent punch-through breakdown, appropriate combination of base doping and base width is necessary in the range of operating voltage of the circuit. The optimum values of base doping and sheet resistance are $Q_{D}$= $1.5{\times}10^{14}$atoms/$\textrm{cm}^2$ and $R_{s}$= 350 $\Omega/\square$ base wodtj $W_{B}$= $2.5{\mu}m$respectively. Under this condition it is possible to control $\beta$ of the transistor to 1500, maintaining $VB_{CBO}$ =200V. To reduce scattered distribution of .beta. of the devices on the wafer, it is necessary to improve emittter predeposition process. As a result, scattered distribution of .beta. of the devices on the wafer was reduced to 1/6 by using the new process. To improve collector to emitter forward voltage drop, $V_{ECF}$ of damper diode, an additional silicon etching process is used, which resulted in improving the value of $V_{eCF}$ from 2.8 V to 1.8V. With the suggested process superior device performance and higher yield are achieved.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.618-618
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• 2013

Graphene is only one atom thick planar sheet of sp2-bonded carbon atoms arranged in a honeycomb crystal lattice, which has flexible and transparent characteristics with extremely high mobility. These noteworthy properties of graphene have given various applicable opportunities as electrode and/or channel for various flexible devices via suitable physical and chemical modifications. In this work, for the development of all-graphene devices, we performed to synthesize alternately patterned structure of mono- and multi-layer graphene by using the patterned Ni film on Cu foil, having much different carbon solid solubilities. Depending on the process temperature, Ni film thickness, introducing occasion of methane and gas ratio of CH4/H2, the thickness and width of the multi-layer graphene were considerably changed, while the formation of monolayer graphene on just Cu foil was not seriously influenced. Based on the alternately patterned structure of mono- and multi-layer graphene as a channel and electrode, respectively, the flexible TFT (thin film transistor) on SiO2/Si substrate was fabricated by simple transfer and O2 plasma etching process, and the I-V characteristics were measured. As comparing the change of resistance for bending radius and the stability for a various number of repeated bending, we could confirm that multi-layer graphene electrode is better than Au/Ti electrode for flexible applications.

• Corrosion Science and Technology
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• 제6권6호
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• pp.304-307
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• 2007

As to the reflection electrode of LCD (liquid crystal displays), silver-copper-gold alloy (hereafter, it is called as ACA (Ag98%, Cu1%, Au1%)) is an effective material of which weathering resistance can be improved more compared with pure silver. However, there is a problem that gold remains on the substrate as residues when ACA is etched in cerium ammonium nitrate solution or phosphoric acid. Gold can not be etched in these etchants as readily as the other two alloying elements. Gold residue has actually been removed physically by brushing etc. This procedure causes damage to the display elements. Another etchant of iodine/potassium iodide generally known as one of the gold etchants can not give precise etch pattern because of remarkable difference in etching rates among silver, copper and gold. The purpose of this research is to obtain a practical etchant for ACA alloy. The results are as follows. The cyanogen complex salt of gold generates when cyanide is used as the etchant, in which gold dissolves considerably. Oxygen reduction is important as the cathodic reaction in the dissolution of gold. A new etchant of sodium cyanide / potassium ferricyanide whose cathodic reduction is stronger than oxygen, can give precise etch patterns in ACA alloy swiftly at room temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1117-1120
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• 2001

Chemical mechanical planarization(CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There have been serious problems in CMP in terms of repeatability and defects in patterned wafers. Since IBM's official announcement on Copper Dual Damascene(Cu2D) technology, the semiconductor world has been engaged in a Cu2D race. Today, even after~3years of extensive R&D work, the End-of-Line(EOL) yields are still too low to allow the transition of technology to manufacturing. One of the reasons behind this is the myriad of defects associated with Cu technology. Especially, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasive and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using Ce$O_2$ is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method for developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.813-815
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• 2008

We prepared highly transparent and conductive Oxide/Metal/Oxide(OMO) multilayer by sputtering and developed wet etching process of OMO with a clear edge shape for the first time. The transmittance and sheet-resistance of the OMO are about 89% and $3.3\;{\Omega}/sq.$, respectively. We adopted OMO as a gate electrode of transparent TFT (TTFT) array and integrated OLED on top of the TTFT to result in high aperture ratio of bottom emission AM-OLED.