• Electrical & Electronic Materials
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• v.10 no.5
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• pp.481-486
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• 1997

This paper describes the anisotropic etching characteristics of Si in acqueous TMAH/IPA solutions. The etch rates of (100) oriented Si crystal planes decrease with increasing TMAH concentration and IPA concentration. Etchant concentration and etch temperature have a large effect on hillock density. Hillock density strongly increase with lower TMAH concentration and higher etch temperature. The etched (100) planes are covered by pyramidal-shaped hillocks below TMAH 15 wt.%, but very smooth surface is obtained TMAH 25 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes. Undercutting ratio of pure TMAH solution is much higher than KOH. But, addition of IPA to TMAh the underrcutting ratio reduces by a factor of 3∼4. Therefore, acqueous TMAH/IPA solution is able to use as anisotropic etchant of Si because of full compability with IC fabrication process.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.71-78
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• 2005

The purpose of this study is to suggest a hyperfine maskless writing technique by using the nanoindentation and HF wet etching technique. Indents were made on the surface of Pyrex7740 glass by the hyperfine indentation process with a Berkovich diamond indenter, and they were etched in $50\;wr\%$ HF solution. After etching process, convex structure was obtained due to the deformation-induced hillock phenomena. In this study, effects of indentation process parameters (etching time, normal load, loading .ate, hold-time at the maximum load) on the morphologies of the indented surfaces after isotopic etching were investigated from an angle of deformation energies. Finally, sample characters were written to show the possibility of the application.

• Journal of Ecology and Environment
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• v.35 no.1
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• pp.35-39
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• 2012

In the current study, several carabid beetle species were proposed as potential biological indicators for different habitat types (levee, upland dike, hillock, and streamside) of agricultural landscapes focusing on agrobiont species. Synuchus arcuaticollis and Synuchus orbicollis were found in all habitat types, indicating that they are general species for all habitat types. Harpalus eous and Synuchus cycloderus are potential bioindicator species for the paddy levee and hillock habitats, respectively. Amara pseudosimplicidens, Anisodactylus punctatipennis, and Chlaenius ocreatus, which occurred widely, and Bembidion morawitzi, which occurred only in the streamside habitat, are potential bioindicators for the streamside habitat.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.316.2-316.2
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• 2016

Device가 점점 Shrinkage 됨에 따라 미세 패터닝을 위하여 기존에 사용하던 박막은 Hardmask 로써 CD(Critical Dimension)가 제한적으로 이를 개선하기 위한 비정질 실리콘 (amorphous silicon)으로 대체하여 사용되는 Layer의 수가 증가하고 있다. 하지만 비정질 실리콘을 증착 시, 하부막에 따른 Adhesion 및 Hillocks과 같은 공정상에서 발생하는 문제들이 발생하게 되는데, 이는 소자의 특성을 떨어뜨리게 된다. 이러한 문제를 해결하고자 본 연구에서는 PECVD를 사용하여 비정질 실리콘 박막을 증착하였고, 그 특성을 분석하였으며, Adhesion 및 Hillock 개선을 위해 비정질 실리콘 박막 증착 전 처리를 최적화하여 특성을 개선하였다. 증착된 박막의 두께 및 굴절률은 Auto thickness measurement로 분석하였고, 표면 특성은 Field emission scanning electron microscopy(FE-SEM 그림 참고), 4 Point Bending TEST를 이용하여 분석을 수행하였다.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1265-1270
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• 2008

Electromigration is a one of a critical failure mechanism in microelectronic devices. Minimizing the thin film interconnections in microelectronic devices make high current densities at electrrical line. Under high current densities, an electromigration becomes critical problems in a microelectronic device. This phenomena under DC conditions was investigated with high temperature. The current density of 1.5MA/cm2 was stressed in interconnections under DC condition, and temperature condition $150^{\circ}C,\;175^{\circ}C,\;200^{\circ}C$. By increasing of thin film interconections, microelectronic devices durability is decreased and it gets more restriction by temperature. Electromigration makes electronic open by void induced, and hillock induced makes electronic short state.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.182-185
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• 2005

Indentation pattern and line pattern were machined on borosilicate(Pyrex 7740 glass) surface using the combination of mechanical machining by $Nanoi-indenter\circledR$ XP and HF wet etching, and a etch-mask effect of the affected layer of the nano-scratched and indented Pyrex 7740 glass surface was investigated. In this study, effects of indentation and scratch process with etching time on the morphologies of the indented and scratched surfaces after isotropic etching were investigated from an angle of deformation energies.

• Journal of the Korean institute of surface engineering
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• v.24 no.4
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• pp.196-205
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• 1991

Multi-level thin films are very important in ULSI applications because of their high electromigration resistance. This study presents the effects of titanium, titanium nitride and titanium tungsten underlayers of the stability of multi-aluminum thin films during isothermal annealing. High purity Al(99.999%) films have been electron-beam evaporated on Ti, TiN, TiW films formed on SiO2/Si (P-type(100))-wafer substrates by RF-sputtering in Ar gas ambient. The hillock growth was increased with annealing temperatures. Growth of hillocks was observed during isothermal annealing of the thin films by scanning electron microscopy. The hillock growth was believed to appear due to the recrystallization process driven by stress relaxation during isothermal annealing. Thermomigration damage was also presented in thin films by grain boundary grooving processes. It is shown that underlayers of Al/TiN/SiO2, Al/TiW/SiO2 thin films are preferrable to Al/SiO2 thin film metallization.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.449-455
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• 1997

The anisotropic etching behavior of single crystal silicon were studied in aqueous KOH solution. N-type (100) oriented single crystal silicon wafers were used for the study, and the $SiO_2$ layer, whose etching rate is known to be much slower than that of silicon in the KOH solution, was used as a mask for the silicon etching. The silicon etching rate and the etching properties are shown to be a function of etchant temperature uniformity, circulation speed, and circulation direction of the etchant as well as the etchant concentration and the temperature. The etching rate is increased as the temperature is increased from $10\mu \textrm{m}/hr$ to $250\mu \textrm{m}/hr$ in the range of $50^{\circ}C~105^{\circ}C$. Hillock density and height is observed to be correlated with the etchant concentration and the etch temperature. The variation of the hillock density was explained by the ratio between the etching rate of (100) orientation and that of (111) orientation.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.426-432
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• 2019

The aim of the present study was to investigate the temporal changes of moth communities in two forest types of the agroecosystem in the southwestern part of Korea, an isolated hillock forest and a continuous mountain forest. Temporal changes in the numbers of moth species and individuals at both forests showed no significant difference, although the numbers of individuals in the isolated hillock forest were decreased. The relationship between changes in moths and body size based on wingspan revealed that the larger moths decreased more in the isolated hillock forest, whereas no effect of body size on change of moths was observed in continuous mountain forest samples. Non-metric multidimensional scaling resulted in the grouping of moth communities by forest types and 10-year time intervals. In the future, long-term monitoring is needed to track the changes in moth communities in agroecosystems. Additionally, we need to investigate the effect of other ecological variables on changes in moth diversity.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.1
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• pp.33-40
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• 1992

Several etching phenomena were observed and analyzed in diaphragm process performed on 4-inch (100) Si wafers for sensor application. In case of deep etching to above 300$\mu$m depth, the etch-defects appeared at etched surface could be classified into three categories such as hillocks, reaction products, and white residues. It was known that the hillock had a pyramidal shape or trapizoidal hexahedron structure depending on the density and size of the reaction products. The IR spectra showed that the white residue, which was due to the local over-saturation of Si dissolved in solution, was mostly Si-N-O compounds mixed with a small amount of H and C etc. Also, the difference in both the existence of etch-defects and etch rate distribution over a whole wafer was investigated when the etched surfaces were downward, upward horizontally and erective in etching solutions. The obtained data were analyzed through flow pattern in the etching bath. As the results, the downward and erective postures were favorable in the etch rate uniformity and the etch-defect removal, respectively.