• 한국정보통신학회논문지
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• 제17권8호
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• pp.1796-1803
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• 2013

본 논문에서는 IE3D를 기반으로 하는 새로운 PSO(Particle Swarm Optimization) 알고리즘을 사용해 이동통신용마이크로스트립 패치 안테나를 설계하였다. 본 논문의 목적은 이동통신용 급전 사각형 마이크로스트립 안테나를 설계하고, 대역폭의 복사 매개변수에 대한 안테나 크기(길이, 폭) 및 기판 매개변수 상대 유전 상수(${\varepsilon}r$), 기판 두께의 영향을 연구하여 이동통신용에 적합한 안테나를 설계하는 것이다. 안테나 설계 프로그램인 IE3D에 PSO알고리즘을 적용하여 안테나의 낮은 입력저항, 대역폭, 안테나의 이득 등을 개선하였다.

• 한국전기전자재료학회논문지
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• 제17권7호
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• pp.713-717
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• 2004

In this study, the etched trench properties including cross-sectional profile, surface roughness, and crystalline defects were investigated depending on the various silicon etching and additive gases, For the case of HBr$He-O_2SiF_4$ trench etching gas mixtures, the excellent trench profile and minimum defects in the silicon trench were achieved. Due to the residual oxide film grown by the additive oxygen gas, which acts as a protective layer during trench etching, the undercut and defects generation in the trench were suppressed. To improve the electrical characteristics of trench gate, the hydrogen annealing process after trench etching was also adopted. Through the hydrogen annealing, the trench corners might be rounded by the silicon atomic migration at the trench corners having high potential. The rounded trench corner can afford to reduce the gate electric field and grow a uniform gate oxide. As a result, dielectric strength and TDDB characteristics of the hydrogen annealed trench gate oxide were remarkably increased compared to the non-hydrogen annealed one.

• 한국표면공학회지
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• 제49권2호
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• pp.119-124
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• 2016

Plasma electrolytic oxidation (PEO) is a promising coating process to produce ceramic oxide on valve metals such as Al, Mg and Ti. The PEO coating is carried out with a dilute alkaline electrolyte solution using a similar technique to conventional anodizing. The coating process involves multiple process parameters which can influence the surface properties of the resultant coating, including power mode, electrolyte solution, substrate, and process time. In this study, ceramic oxide coatings were prepared on commercial Al alloy in electrolytes with different KOH concentrations (0.5 ~ 4 g/L) by plasma electrolytic oxidation. Microstructural and electrochemical characterization were conducted to investigate the effects of electrolyte concentration on the microstructure and electrochemical characteristics of PEO coating. It was revealed that KOH concentration exert a great influence not only on voltage-time responses during PEO process but also on surface morphology of the coating. In the voltage-time response, the dielectric breakdown voltage tended to decrease with increasing KOH concentration, possibly due to difference in solution conductivity. The surface morphology was pancake-like with lower KOH concentration, while a mixed form of reticulate and pancake structures was observed for higher KOH concentration. The KOH concentration was found to have little effect on the electrochemical characteristics of coating, although PEO treatment improved the corrosion resistance of the substrate material significantly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.293-295
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• 1994

Barium Titanate ($BaTiO_3$) is one of the few titanateds which is cubic at room temperature. It has the perovskite structure, high dielectric constant (${\varepsilon}_r=300$) and a small temperature coefficient of resistance due to it's Low transition temperature ($Tc=120^{\circ}c$). PTCR (Positive Temperature Coefficient of Resistivity) thermistor in thin film $BaTiO_3$ system was prepared by using radio frequency (13.56MHz) and BC magnetron sputter equipment. Polycrystalline, and surface structure characteristics of the specimens were measured by X-ray diffraction (D-Max3, Rigaku, Japan), SEM(Scanning Electron Microscopy: M. JSM84 01, Japan), respectively. Temperature at below $600^{\circ}C$, $1000^{\circ}C$ to $700^{\circ}C$, and above $1100^{\circ}C$ for spotted $BaTiO_3$ thin films showed the amorphous, degree of crystal growth, and polycrystalline, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.421-424
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• 2004

As the deep sub-micron devices are recently integrated high package density, novel process method for sub $0.1{\mu}m$ devices is required to get the superior thin gate oxide characteristics and reliability. However, few have reported on the electrical quality and reliability on the thin gate oxide. In this paper I will recommand a novel shallow trench isolation structure for thin gate oxide $30{\AA}$ of deep sub-micron devices. Different from using normal LOCOS technology, novel shallow trench isolation have a unique 'inverse narrow channel effects' when the channel width of the devices is scaled down shallow trench isolation has less encroachment into the active device area. Based on the research, I could confirm the successful fabrication of shallow trench isolation(STI) structure by the SEM, in addition to thermally stable silicide process was achiever. I also obtained the decrease threshold voltage value of the channel edge and the contact resistance of $13.2[\Omega/cont.]$ at $0.3{\times}0.3{\mu}m^2$. The reliability was measured from dielectric breakdown time, shallow trench isolation structure had tile stable value of $25[%]{\sim}90[%]$ more than 55[sec].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.333-334
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• 2006

The objective of this study is to fabricate a piezoelectric composite consisting of a piezoelectric ceramic and a high toughness material and to evaluate their electromechanical properties for high force actuator applications. The mixture of the piezoelectric material, PMNZT, and high toughness material, $ZrO_2$, exhibited high piezoelectric properties as well as good mechanical fracture resistance. Up to 2 vol% of $ZrO_2$ in PMNZT matrix, piezoelectric $d_{33}$ coefficient was above 400 pC/N, being 80% of that for the original PMNZT, and the toughness showed twice of the PMNZT. When the volume fraction of the $ZrO_2$ was above 5%, however, the piezoelectric coefficient became abruptly decreased and it approached 20% of value for the PMNZT.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.207.1-207.1
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• 2013

Tantalum oxide has been extensively investigated as one of the promising Resistive switching materials applicable to Resistive Dynamic Access Memories. Impedance spectroscopy offers simultaneous measurements of electrical and dielectric information, separation of electrical origins among bulk, grain boundaries, and interfaces, and the monitoring of electrical components. Such benefits have been combined with the resistive states of resistive switching devices which can be described in terms of equivalent circuits involving resistors, capacitors, and inductors, The current work employed pulsed laser deposition in order to prepare the oxygen-deficient tantalum oxide. The fabricated devices were controlled between highresistance and low-resistance states in controlled current compliance modes. The corresponding electrical phenomena were monitored both in the dc-based current-voltage characteristics and in the ac-based impedance spectroscopy. The origins of the electrical switching are discussed towards optimized ReRAM devices in terms of interfacial effects.

• 한국정밀공학회지
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• 제18권12호
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• pp.192-199
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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 hale been serious problems in CMP in terms of repeatability and deflects in patterned wafers. Especial1y, 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 abrasives and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using CeO$_2$is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method fur developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• Advances in materials Research
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• 제2권2호
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• pp.119-131
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• 2013

Impedance and electrical conduction studies of $Ba(Nd_{1/2}Nb_{1/2})O_3$ ceramic prepared using conventional high temperature solid-state reaction technique are presented. The crystal symmetry, space group and unit cell dimensions were estimated using Rietveld analysis. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with space group $Pm\bar{3}m$. Energy dispersive X-ray analysis and scanning electron microscopy studies were carried to study the quality and purity of compound. The circuit model fittings were carried out using the impedance data to find the correlation between the response of real system and idealized model electrical circuit. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type and negative temperature coefficient of resistance character. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in $Ba(Nd_{1/2}Nb_{1/2})O_3$. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy.

• 한국진공학회지
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• 제6권S1호
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• pp.122-126
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• 1997

the Cu/polyimide system is known to be the best candidate for a multilevel interconnection system due to the low resistance of Cu and to the low dielectric constant of polyimide respectively. Ion beam mixing of Cu(40nm)/polyimide was carried out at room temperature with 80 keV Ar+ and N2+ form $1.5\times$1015 to 15$\times$1015 ions/cm2. The quantitative adhesion strength was measured by a standard scratch test. X-ray photoelectron spectroscopy and x-ray emission spectrocopy are employed to investigate the chemical bonds and the interlayer compound formation of the films Cu/Al/polyimide showed more adhesion strength than Cu/polyimide after ion beam mixing and N2+ ions are more effective in the adhesion enhancement than Ar+ with the same sample geometry. The XES results shows the formation of interlayer compound of CuAl2O4 which can reflect more adhesive Cu/Al/polyimide which has not been reported previously. The latter results is understood by the fact that N2+ ions produce more pyridinelike moiety, amide group and tertiary amine moiety whcih are known as adhesion promotors.