• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.70-71
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• 2007

Multicrystalline silicon(mc-Si) solar cells are steadily increasing their share of the PV market due to the lower material costs. However, commercial mc-Si solar cells have lower efficiency than singlecrystalline silicon solar cells. To improve efficiency of mc-Si solar cells, it is important to reduce optical losses from front surface reflection. Isotropic etching with acid solution based on hydrofluoric acid(HF) and nitric acid$(HNO_3)$ is one of the promising methods that can reduce surface reflectance for mc-Si solar cells. Anisotropic etching is not suitable for mc-Si because of its various grain orientations. In this paper, we isotropically etched mc-Si using acid solution. After that, etched surface was observed by Scanning Electron Microscope(SEM) and surface reflectance was measured. We obtained 29.29% surface reflectance by isotropic etching with acid solution in wavelength from 400nm to 1000nm for fabrication of mc-Si solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.352-353
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• 2006

가스센서용 마이크로 히터 제작에는 표연 마이크로 머시닝 또는 벌크 마이크로머시닝 기술을 이용한다. 표면 마이크로 머시닝에 의한 마이크로 히터 (MHP) 구조의 경우, 기판과 박막간의 폭이 좁기 때문에 에칭 공정 후 세정이 잘 이루어지지 않으면 열적 절연이 잘 이루어지지 않아서 히터와 센서의 성능을 저하시키는 원인이 된다. 본 연구에서는 표면 마이크로 머시닝 기술에 의한 가스 센서용 마이크로 히터를 제작한다. $SiO_2$와 $Si_3N_4$를 성분으로 하며, $100{\mu}m\;{\times}\;100{\mu}m$의 면적과 350 nm 의 두께를 갖는 가스 센서용 마이크로 히터를 제작하였다. 이를 위하여 ANSYS를 통한 유한요소해석에 의한 열분포 해석으로 최적구조를 확인하였다. 센서로의 열 전달 효율을 높이기 위해 센서 박막은 히터 위에 적층하였다. 실리콘 표면과 마이크로 히터와의 간격은 에칭 공정을 통하여 $2{\mu}m$로 하였으며, 이 공간에서는 에칭 및 세정 후에 이물질이 깨끗이 세정되지 않고 남아 있거나, 습식 공정 중에 수분의 장력에 의한 열전연성이 나빠질 수 있는 등 단점이 있다. 이는 건식 등방성 에칭 공정을 통하여 해결하였다.

• 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.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.1-6
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• 2002

Micro engine that includes Micro scale combustor is fabricated. Design target was focused on the observation of combustion driven actuation in MEMS scale. Combustor design parameters are somewhat less than the size recommended by feasibility test. The engine structure is fabricated by isotropic etching of the photosensitive glass wafers. Electrode is formed by electroplating of the Nickel. Photosensitive glass can be etched isotropically with almost vertical angle. Bonding and assembly of structured photosensitive glass wafer from the engine. Combustor size was determined to be 1mn scale. Piston in cylinder moves by fuel injection and reaction. In firing test, adequate engine operation including ignition, flame propagation and piston motion was observed. Present study warrants further application research on MEMS scale internal combustion power units.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.661-669
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• 1999

A probe card is one of the most important pan of test systems as testing IC(integrated circuit) chips. This work was related to bump-type silicon vertical probe card which enabled simultaneous tests for multiple semiconductor chips. The probe consists of silicon cantilever with bump tip. In order to obtain optimum size of the cantilever, the dimensions were determined by FEM(finite element method) analysis. The probe was fabricated by RIE(reactive ion etching), isotropic etching, and bulk-micromachining using SDB(silicon direct bonding) wafer. The optimum height of the bump of the probe detemimed by FEM simulation was 30um. The optimum thickness, width, and length of the cantilever were 20 $\mum$, 100 $\mum$,and 400 $\mum$,respectively. Contact resistance of the fabricated probe card measured at contact resistance testing was less than $2\Omega$. It was also confirmed that its life time was more than 20,000 contacts because there was no change of contact resistance after 20,000 contacts.