• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2515-2517
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• 1998

The micro fresnel lens(MFL) was modeled and fabricated on a XY-stage electrostatically driven by comb actuator. The modeled MFL was approximated as a step shape with 4-phase and 4-zone plate. The focal length and diameter of the MFL is 20mm and 912${\mu}m$, respectively. The XY-stage suspending the MFL is designed to generate a large static displacement up to about 20${\mu}m$. On SOI substrates, we first fabricated MFL using the RIE(reactive Ion etching) technology and then patterned and etched bulk silicon to make XY-stage. After the fabrication of all structures on top side of the SOI substrates. $Si_3N_4$ was deposited for passivation of all structures using PECVD(plasma enhanced chemical vapor deposition). All the MFL systems width comb drive actuator were released by KOH etching from the bottom side of the SOI wafer using double-sided alignment technique. In fabrication of MFL, a dry etching conditions is established in order to improve surface roughness and to control the etched depth.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.64-68
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• 2017

The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.20-23
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• 2004

As the integrated circuit device shrinks to the smaller dimension, the chemical mechanical polishing(CMP) process was required for the global planarization of inter-metal dielectric(IMD) layer with free-defect. However, as the IMD layer gets thinner, micro-scratches are becoming as major defects. Chemical-Mechanical polishing(CMP) of conductors is a key process in Damascene patterning of advanced interconnect structure. The effect of alternative commercial slurries pads, and post-CMP cleaning alternatives are discuss, with removal rate, scratch dentisty, surface roughness, dishing, erosion and particulate density used as performance metrics. Electroplated copper deposition is a mature process from a historical point of view, but a very young process from a CMP perspective. While copper electro deposition has been used and studied for decades, its application to Cu damascene wafer processing is only now gaining complete acceptance in the semiconductor industry. The polishing mechanism of Cu-CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. however it is important to understand the effect of oxidizer on copper passivation layer in order to obtain higher removal rate and non-uniformity during Cu-CMP process. In this paper, we investigated the effects of oxidizer on Cu-CMP process regarding the additional volume of oxidizer.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.727-731
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• 2021

In this study, we have investigated a selective emitter using a UV laser on BBr₃ diffusion doping layer. The selective emitter has two regions of high and low doping concentration alternatively and this structure can remove the disadvantages of homogeneous emitter doping. The selective emitters were fabricated by using UV laser of 355 nm on the homogeneous emitters which were formed on n-type Si by BBr₃ diffusion in the furnace and the heavy boron doping regions were formed on the laser regions. In the optimized laser doping process, we are able to achieve a highly concentrated emitter with a surface resistance of up to 43 Ω/□ from 105 ± 6 Ω/□ borosilicate glass (BSG) layer on Si. In order to compare the characteristics and confirm the passivation effect, the annealing is performed after Al₂O₃ deposition using an ALD. After the annealing, the selective emitter shows a better effect than the high concentration doped emitter and a level equivalent to that of the low concentration doped emitter.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.412-425
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• 2021

Because austenitic stainless steel causes localized corrosion such as pitting and crevice corrosion in environments containing chlorine, corrosion resistance is improved by surface treatment or changes of the alloy element content. Accordingly, research using cyclic potentiodynamic polarization experiment to evaluate the properties of the passivation film of super austenitic stainless steel that improved corrosion resistance is being actively conducted. In this investigation, the electrochemical properties of austenitic stainless steel and super austenitic stainless steel were compared and analyzed through cyclic potentiodynamic polarization experiment with varying temperatures. Repassivation properties were not observed in austenitic stainless steels at all temperature conditions, but super austenitic stainless steels exhibited repassivation behaviors at all temperatures. This is expressed as α values using a relational formula comparing the localized corrosion rate and general corrosion rate. As the α values of UNS S31603 decreased with temperature, the tendency of general corrosion was expected to be higher, and the α value of UNS N08367 increased with increasing temperatures, so it is considered that the tendency of localized corrosion was dominant.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.81-92
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• 1997

Rear floating junction cell (RFJC), using the buried contact technology, is capable of eliminating the efficiency limitations on the single sided cells by providing betterear surface passivation. The implementation of this structure, is simpler and lower in cost and therefore viable for commercial production. However, the contributions, due to damages in the two sets of grooves, to the total dark saturation current density has limited the achievable efficiency of the RFJC to only 21.5 %. This Paper reports on the efficiency estimates of RFJC using PC-1D.

• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.225-232
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• 1997

The performance characteristics of high rate discharge LiSOCl2 cells are highly affected by carbon cathode. During the cell discharge, SOCl2 reduction takes place at the porous carbon cathode, resulting in the precipitation of reaction products, mainly LiCl, within the pores of the substrate. This leads to eventual passivation of the cathode surface and resulting cell failure. To improve the cathode performance, we ex-amined discharge reactions of cathodes (half-cell, 50 mA/$\textrm{cm}^2$ constant current) with various surface density and thickness. The carbon cathode with the optimum capacity for our application is surface density 0.04 g/$\textrm{cm}^2$ and thickness 1.4mm carbon. The carbon cathode with surface density 0.04g/$\textrm{cm}^2$ and thickness 1.4 mm exhibits decreased polarization, increased discharge duration time and capacity (Ah/$\textrm{cm}^2$) as compared with that with surface density 0.04g/$\textrm{cm}^2$ and thickness 0.8mm. The porosities analyses on the two carbon cathodes show that total pore volume of the carbon cathode with thickness 1.4 mm is larger than that with thickness 0.8mm. The increased volume of mesopores (0.05$\mu$m~0.5$\mu$m) and macropores(>0.5$\mu$m) is ob-served with the carbon cathode with thickness 1.4mm as compared with that with thickness 0.8mm, which can be related with the observed capacity increase. We observed LiCl crystals, cubic crystallites and fused, plate-like aggregates, and some elemental S as discharge products by EDS and XRD.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.535-541
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• 1997

The effect of concentration of each solution( HCI, $H_2SO_4$ and $HNO_3$), scan rate and polished surface condition on the corrosion of AISI 304 Stainless Steel were investigated, utilizing the Method ASTM G5 - 87. It can be concluded that: 1) For the same concentration(i.e. 1N) of each solution the corrosion rate is the highest in HCI and lowest in $HNO_3$. Also, the difference of values of $i_{cirt}$ generated for each solution is significant. 2) As the concentration of the solution $H_2SO_4$ is increased (O.5N, 1N, 2N) the values of $E_{cor}$ $i_{crit}$ and $i_{p}$ are increased. 3) In case of existence of SCN ion of O.OlN, the values of iCTIt and ip generated are approximately 100 times and 1.4 times higher respectively, than in the case of non - existence of $SCN^{-}$. However the existence of $SCN^{-}$ doesn't affect the value of $E_{cor}$ and $E_{p}$. 4) The values of $i_{crit}$ and $i_{p}$ are increased due to the increase of scan rate. But the values of $E_{cor}$ and $E_{p}$ do not depend on the scan rate. 5) The $i_{p}$ value depends greatly on oxygen in the solution, but the changes in values of $E_{cor}$ $i_{crit}$ and $E_{b}$ due to the oxygen are insignificant. 6) If a component is polished using #400, #600 and #800 wet polish paper, the effect of surface condition on variations of values of $i_{crit}$ and $i_{p}$ is slightly significant.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.128-132
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• 2004

Short wave infrared (SWIR) photovoltaic devices have been fabricated from metal organic vapour phase epitaxy (MOVPE) grown n- on p- HgCdTe films on GaAs substrates. The MOVPE grown films were processed into mesa type discrete devices with wet chemical etching employed for meas delineation and ZnS surface passivatlon. ZnS was thermally evaporated from effusion cell in an ultra high vacuum (UHV) chamber. The main features of the ZnS deposited from effusion cell in UHV chamber are low fixed surface charge density, and small hysteresis. It was found that a negative flat band voltage with -0.6 V has been obtained for Metal Insulator Semiconductor (MIS) capacitor which was evaporated at $910^{\circ}C$ for 90 min. Current-Voltage (I-V) and temperature dependence of the I-V characteristics were measured in the temperature range 80 - 300 K. The Zero bias dynamic resistance-area product ($R_{0}A$) was about $7500{\Omega}-cm^{2}$ at room temperature. The physical mechanisms that dominate dark current properties in the HgCdTe photodiodes are examined by the dependence of the $R_{0}A$ product upon reciprocal temperature. From theoretical considerations and known current expressions for thermal and tunnelling process, the device is shown to be diffusion limited up to 180 K and g-r limited at temperature below this.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.77-80
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• 2003

Adsorption of glycine on$Si_3N_4$powder surface has been investigated, which is supposed to enhance the formation of passive layer inhibiting oxidation in aqueous solution. In the basic solution, multinuclear surface complexing between Si and dissociated ligands was responsible for the saturated adsorption of glycine. In addition, $CeO_2$-based CMP slurry containing glycine was manufactured and then applied to planarize$SiO_2$and$Si_3N_4$thin film. Owing to the passivation by glycine, the removal rates, Rh, were decreased, however, the selectivities, RE(SiO$_2$)/RR($Si_3N_4$), increased and showed maximum at pH=12. The suppressed oxidation and dissolution by adsorbate were correlated with the dissociation behavior of glycine at different pH and subsequent chemical adsorption.