• Nuclear Engineering and Technology
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• v.37 no.4
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• pp.395-400
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• 2005

An environmental radon monitoring system, comprising a radon-cup, an etching system, and a track counting system, was constructed. The radon cup is a cylindrical chamber with a radius of 2.2 cm and a height of 3.2 cm in combination with a CR-39 detector. Carbon is impregnated in the bodies of the detector chamber to avoid problem of an electrostatic charge. The optimized etching condition for the CR-39 exposed to a radon environment turned out to be a 6 N NaOH solution at 70^{\circ}$ over a 7hour period. The bulk etch rate under the optimized condition was $1.14{\pm}0.03\;{\mu}m\;h^{-1}$. The diameter of the tracks caused by radon and its progeny were found to be in the range of $10\~25\;{\mu}m$ under the optimized condition. The track images were observed with a track counting system, which consisted of an optical microscope, a color charged couple device (CCD) camera, and an image processor. The calibration factor of this system is obtained to be $0.105{\pm}0.006$ tracks $cm^2$ per Bq $m^{-3}$ d.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.189-194
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• 2011

Si-cell was prepared with various types owing to the etching times textured by the KOH etching solution. The pn junction for solar cell was prepared on p-type Si wafer by the furnace using the $POCl_3$ and oxygen mixed precursor, and the metalization was done using by the Al back electrode and Ag front electrode. Textured Si surface was etched by the pyramid formation. The efficiency and the fill factor was increased in the Si-cell with a large size of pyramids, because of the series resistances decrease depending on the increasing of the photon absorbance. Increasing of the absorbance occurred the induction of the short current and open voltage, and then the efficiency was increased.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.38-46
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• 2005

In laser machining such as drilling with $CO_2$ or Nd:YAG laser, and etching or ablation with Excimer laser, one of the most important parameters affecting the machining is known to be beam characteristics. In this paper a numerical study is performed to investigate the effects of beam parameters, especially in the process of excimer laser ablation of polymers. Results of different beam conditions reveal that if the ablated depth is small compared to beam size the simple photochemical etching model is suitable to predict the etched shape, and that the importance of precise alignment becomes large as beam quality factor becomes larger.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1224-1231
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• 2003

This paper reports on the air-gap type thin film bulk acoustic wave resonator(FBAR) using ultra thin wafer with thickness of 50$\mu\textrm{m}$. It was fabricated to realize a small size devices and integrated objects using MEMS technology for flexible microsystems. To reduce a error of experiment, MATLAB simulation was executed using material characteristic coefficient. Fabricated thin FBAR consisted of piezoelectric film sandwiched between metal electrodes. Used piezoelectric film was the aluminum nitride(AlN) and electrode was the molybdenum(Mo). Thin wafer was fabricated by wet etching and dry etching, and then handling wafer was used to prevent damage of FBAR. The series resonance frequency and the parallel frequency measured were 2.447㎓ and 2.487㎓, respectively. Active area is 100${\times}$100$\mu\textrm{m}$$^2$.Q-factor was 996.68 and K$^2$$\_$eff/ was 3.91％.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.31-35
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• 2011

For high efficiency of Si-cells, Si wafers were textured by the KOH and NaOH etching solution to decreas the reflectance at surfaces of the cells. The textured surfaces were shown various types such as isotropic and anisotropic depending on the etching solution. The reflectance at sample of an anisotropic form with pyramid type was lower than that of isotropic form. The surface with isotropic form of general tiny circles on the surface increased the efficiency, however, the reflectance of it was increased. The efficiency was increased on surface with low roughness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2335-2341
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• 1999

The $2\times32$ coupler consists of Mach-Zehnder interferometer and Y branch coupler. For the designs of this coupler, three dimensional rectangular core waveguide decomposed to two-dimensional structure by the effective index method. To optimize the waveguide structure, the confinement factor was investigated with two-dimensional finite difference Beam Propagation Method. The $2\times32$ coupler fabricated by simulation with height between Mach-Zehnder arms, H=$43.6\mu\textrm{m}$(path difference $0.668\mu\textrm{m}$) was showed best characteristics. In the results of dry etching of core layer, the etching rate of core layer was above 2600${\AA}$/min, the etching ratio of SiO2 to Al mask was 30:1 and the uniformity of etching was $\pm$5%. The maximum insertion loss and the uniformity of $2\times32$ coupler were below 19.2dB, 2dB respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.4
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• pp.390-395
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• 2004

A semiconductor manufacturing process is the complicate and dynamic process, and consists of many sub-processes. An etching process is the most important process in the semiconductor fabrication. In this paper, the decision support system based upon data mining and knowledge discovery is an important factor to improve the productivity and yield. The proposed decision support system consists of a neural network model and an inference system based on fuzzy logic Firstly, the product results are predicted by the neural network model constructed by the product patterns that represent the quality of the etching process. And the product patters are classified by expert's knowledge. Finally, the product conditions are estimated by the fuzzy inference system using the rules extracted from the classified patterns. Prediction of product qualities can be linked to each input and process variables. We employ data mining and intelligent techniques to find the best condition of the etching process. The proposed decision support system is efficient and easy to be implemented for the process management based upon expert's knowledge.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.217-222
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• 2014

In order to improve the heat efficiency of the general residential boiler, we performed an experiment of condensation heat transfer to air pre-heating exchanger adhered to the condensing boiler. In this study, surface roughness was imposed on the surface of stainless steel by etching. And in order to evaluate the heat transfer performance on each plate, the counter flow heat exchanger fabricated with polycarbonate in used. As a result, on etching treated plate's overall heat transfer coefficient is higher than the original plate. And etching treated plate during 60 seconds with etchant is the to average 15% compared to bare stainless steel. And we studied the heat transfer enhancement factor through the analysis of surface characteristics using AFM.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2105-2107
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• 2004

In this study, Spiral inductors on the $SiO_2$/Si(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of 2 ${\mu}m$ was deposited on the substrate. Also we fabricated square inductors through the wet chemical etching technique. The inductors are completely specified by the turn width and the spacing between spirals. Both the width and spacing between spirals were varied from 10 to 60 ${\mu}m$ and from 20 to 70 ${\mu}m$, respectively. Inductance and Q factor dependent on the RF frequency were investigated to analyze performance of inductor arrays. Also, We recommend that the reasonable Q-factors, spec's turns and thickness of the coil for inductors cab be set to be ideal condition.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.263-267
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• 2014

Super junction trench gate power MOSFETs have been receiving attention in terms of the trade-off between breakdown voltage and on-resistance. The vertical structure of super junction trench gate power MOSFETs allows the on-resistance to be reduced compared with conventional Trench Gate Power MOSFETs. The heat release of devices is also decreased with the reduction of on-resistance. In this paper, Lattice Temperature of two devices, Trench Gate Power MOSFET and Super junction trench gate power MOSFET, are compared in several temperature circumstance with the same Breakdown Voltage and Cell-pitch. The devices were designed by 100V Breakdown voltage and measured from 250K Lattice Temperature. We have tried to investigate how much temperature rise in the same condition. According as temperature gap between top of devices and bottom of devices, Super junction trench gate power MOSFET has a tendency to generate lower heat release than Trench Gate Power MOSFET. This means that Super junction trench gate power MOSFET is superior for wide-temperature range operation. When trench etching process is applied for making P-pillar region, trench angle factor is also important component. Depending on trench angle, characteristics of Super junction device are changed. In this paper, we focus temperature characteristic as changing trench angle factor. Consequently, Trench angle factor don't have a great effect on temperature change.