• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.81-86
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• 2004

A new method to improve the wet etching characteristics is described. The anisotropic wet-etching of (100) Si with megasonic wave has been studied in KOH solution. Etching characteristics of p-type (100) 6 inch Si have been explored with and without megasonic irradiation. It has been observed that megasonic irradiation improves the characteristics of wet etching such as an etch uniformity and surface roughness. The etching uniformity on the whole wafer with and without megasonic irradiation were less than ${\pm}1\%$ and more than $20\%$, respectively. The initial root-mean-square roughness($R_{rms}$) of single crystal silicon is 0.23 nm. It has been reported that the roughnesses with magnetic stirring and ultrasonic agitation were 566 nm and 66 nm, respectively. Comparing with the results, etching with megasonic irradiation achieved the Rrms of 1.7 nm on the surface after the $37{\mu}m$ of etching depth. Wet etching of silicon with megasonic irradiation can maintain nearly the original surface roughness after etching process. The results have verified that the megasonic irradiation is an effective way to improve the etching characteristics such as etch uniformity and surface roughness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.4
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• pp.131-134
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• 2016

The conditions for chemical polishing and etching technique were investigated to reveal surface defects in RE : YAG ($RE=Nd^{3+},\;Er^{3+},\;Yb^{3+}$) single crystals grown by Czochralski method. The optimal condition for chemical polishing was in 85 % $H_3PO_4$ solution at $330^{\circ}C$ for 30 minutes with a specimen fixed in the vertical direction. In addition, the optimal condition for chemical etching was in 85 % $H_3PO_4$ solution at $260^{\circ}C$ for 1 hour, and $70{\sim}80{\mu}m$ sized triangular etch pits were observed on (111) face. As a result of defect density analysis, $1.9{\times}10^3/cm^2$ for Nd(1 %) : YAG, $4.3{\times}10^2/cm^2$ for Er(7.3 %) : YAG, and $5.1{\times}10^2/cm^2$ for Yb(15 %) : YAG were measured.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.23-27
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• 2011

Fabrication of porous silicon(PS) double layer by electrochemical etching is the first step in process of ultrathin solar cell using PS layer transfer process. The porosity of the porous silicon layer can be controlled by regulating the formation parameters such as current density and HF concentration. PS layer is fabricated by electrochemical etching in a chemical mixture of HF and ethanol. For electrochemical etching, highly boron doped (100) oriented monocrystalline Si substrates was used. Ths resistivity of silicon is $0.01-0.02\;{\Omega}{\cdot}cm$. The solution composition for electrochemical etching was HF (40%) : $C_2H_5OH$(99 %) : $H_2O$ = 1 : 1 : 2 (by volume). In order to fabricate porous silicon double layer, current density was switched. By switching current density from low to high level, a high-porosity layer was fabricated beneath a low-porosity layer. Etching time affects only the depth of porous silicon layer.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.113-116
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• 2008

As the integration in semiconductor display develops, semiconductor process becomes multilayer. In order to form several layer patterns, etching process which uses photoresistor (PR) must be performed in multilayer process. Repeated etching processes which take long time and PR residue cause mortal problems in semiconductor. To overcome such problems, we studied about the solution which eliminates PR effectively by using normal dry and wet etching method using plasma activated PR strip solvent in liquid condition. At first, we simulate the device which activates the plasma and make sure whether gas flow in device is uniform or not. Under activated plasma, etching effect is elevated. This improvement reduces etching time as well as display production time of semiconductor process. Generally, increasing etching process increases environmental hazards. Reducing etching process can save the etchant and protect environment as well.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.69-76
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• 1982

The purpose of this study was to evaluate the color penetration of cavity margin with composite resin restorations in some Korean foods substance-soy sauce and hot bean paste. Fifty specimans which were extracted caries free third molar of young adults recently. All of the prepared 100 cavities were filled with two kinds of composite resin (Hipol$^{(R)}$and Restodent$^{(R)}$). The experimental specimans were divided into five groups by the following procedures. Group I : Filling of composite resin and polishing. Group II : Filling, polishing, etching of cavity and sealing. Group III : Etching, sealing, filling and polishing. Group IV : Etching, sealing, filling, polishing, and repeated of etching of cavity margin and sealing. Group V : Etching, sealing, filling, polishing, and sealing again without etching. Before examination, the restorated teeth were subjected to thermal cycling ($4^{\circ}C$ and $60^{\circ}C$). All the specimens were immersed in soy and 30% hot bean paste solution under $37^{\circ}C$ incubator during six weeks. Then, the specimens were sectioned bucco-lingually through the center of two restorations with diamond disk and examined under a. metallographic microscope. (Union 6617 U.S.A.) Thereafter, the degree of color penetration was calculated and analyzed. The obtained results were as follows: 1. The color penetration was the lowest in the procedure of Group III which was acid etching, sealing, composite resing filling, and polishing. 2. The color penetration occured in soy and hot bean paste, but the degree of penetration was not so significant statistically between them. 3. The degree of color penetration was not so significant statistically between Hipol$^{(R)}$ and Restondent$^{(R)}$.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.353-358
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• 2008

In order to increase extraction efficiency of AlGaInP-based vertical RED LEDs, chemical wet etching technique was produced by using a roughened surface with triangle-like morphology. A commonly used $H_3PO_4$-based solution was applied for chemical wet etching. The light extraction of AlGaInP LED was related to the n-side roughed surface morphology. The morphology of roughed surface is analyzed by the atomic force microscope (AFM). As a result, the roughed surface AlGaInP LED has a root-mean-square (RMS) roughness of 44 nm. The brightness shows 41% increase after roughening n-side surface, as compared to the ordinary flat surface LED.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.46-46
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.56-56
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• 2000

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.54-55
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• 1997

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.200-206
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• 2000

The metal impurities in specific regions at near surface of silicon wafer were determined by constant depth etching·lt is possible to etch uniformly over the entire wafer surface by 1$\mu\textrm{m}$ depth with 5 mL of etching solution made up of HF and HNO$_3$ mixed by l:3 volume ratio. The microwave oven was used to evaporate the solution after etching. After spiking, The recoveries of Cu, Ni, Zn, Cr, Mg and K were found to be 99∼105%ted in polysilicon region and could be quantified by 1$\mu\textrm{m}$ depth.