• 한국결정성장학회지
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• 제12권3호
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• pp.120-125
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• 2002

Si-wafers for solar cells were cast in a size of $50{\times}46{\times}0.5{\textrm}{mm}^3$ by vacuum casting method. The graphite mold coated by BN powder, which was to prevent the reaction of carbon with the molten silicon, was used. Without coating, the wetting and reaction of Si melt to graphite mold was very severe. In the case of BN coating, SiC was formed in the shape of tiny islands at the surface of Si wafer by the reaction between Si-melt and carbon of the graphite mold on the high temperature. The grain size was about 1 mm. The efficiency of Si solar cell was lower than that of Si solar cell fabricated on commercial single and poly crystalline Si wafer. The reason of low efficiency was discussed.

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2439-2443
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• 2011

태양전지를 제작하는데 실리콘기판 표면에서의 광 흡수를 증가시키기 위한 표면조직화를 위해서 염기 용액을 이용한 습식방법을 이용하여 샘플을 제작하였다. 이렇게 준비된 염기성 에칭용액을 이용한 실리콘 웨이퍼의 표면 상태를 관찰하여 광학적 특성과의 연관성을 조사하였다. 표면조직화가 표면 전체적으로 고르게 이루어진 샘플에서 반사도가 낮았으며, 광학적 특성이 좋게 나타났다. 에칭이 과도하게 일어난 샘플에서는 오히려 반사도가 증가하여 광학적 특성이 떨어지는 것을 확인 하였다.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.479-485
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• 2002

We have investigated the effects of various wafers cleaning on glass/Si bonding using 4 inch Pyrex glass wafers and 4 inch silicon wafers. The various wafer cleaning methods were examined; SPM(sulfuric-peroxide mixture, $H_2SO_4:H_2O_2$ = 4 : 1, $120^{\circ}C$), RCA(company name, $NH_4OH:H_2O_2:H_2O$ = 1 : 1 : 5, $80^{\circ}C$), and combinations of those. The best room temperature bonding result was achieved when wafers were cleaned by SPM followed by RCA cleaning. The minimum increase in surface roughness measured by AFM(atomic force microscope) confirmed such results. During successive heat treatments, the bonding strength was improved with increased annealing temperatures up to $400^{\circ}C$, but debonding was observed at $450^{\circ}C$. The difference in thermal expansion coefficients between glass and Si wafer led debonding. When annealed at fixed temperatures(300 and $400^{\circ}C$), bonding strength was enhanced until 28 hours, but then decreased for further anneal. To find the cause of decrease in bonding strength in excessively long annealing time, the ion distribution at Si surface was investigated using SIMS(secondary ion mass spectrometry). tons such as sodium, which had been existed only in glass before annealing, were found at Si surface for long annealed samples. Decrease in bonding strength can be caused by the diffused sodium ions to pass the glass/si interface. Therefore, maximum bonding strength can be achieved when the cleaning procedure and the ion concentrations at interface are optimized in glass/Si wafer direct bonding.

• 한국산학기술학회논문지
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• 제3권2호
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• pp.74-79
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• 2002

80년대 반도체 산업의 급격한 성장으로 오늘날 반도체 산업은 반도체소자의 초고집접화, 웨이퍼의 대구경화로 발전이 거듭났으며, 소자의 성능과 생산 수율의 향상을 위하여 실리콘 웨이퍼의 세정하는 기술 및 연구를 계속 진행하고 있다. 기존의 반도체 세정은 과다한 화학약품의 사용으로 비 환경친화적이며, 이에 본 연구에서는 기존의 세정방법을 대체하기 위한 방법으로 환경친화적인 전리수를 이용한 반도체 세정법을 하였다. 이때 실리콘 웨이퍼 표면의 원자적 상태의 변화가 발생하여 다양한 방법으로 확인할 수 있다. 본 연구에 서는 이러한 분석을 하기 위하여 기존세정의 화학약품과 전리수로 세정한 웨이퍼의 표면을 비교하였으며, 또한 온도 및 시간별 표면상태변화를 분석하였다. 특히 접촉각 변하에 중점을 두어 변화를 관찰하였으며, 음극수의 경우 17.28°, 양극수의 경우 34.1°의 낮은 접촉각을 얻을 수 있었다.

• 신재생에너지
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• 제4권2호
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• pp.68-73
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• 2008

It is very important that constitution of good hetero-junction interface with a high quality amorphous silicon thin films on very cleaned c-Si wafer for making high efficiency hetero-junction solar cells. For achieving the high efficiency solar cells, the inspection and management of c-Si wafer surface conditions are essential subjects. In this experiment, we analyzed the c-Si wafer surface very sensitively using Spectroscopic Ellipsometer for < ${\varepsilon}2$ > and u-PCD for effective carrier life time, so we accomplished < ${\varepsilon}2$ > value 43.02 at 4.25eV by optimizing the cleaning process which is representative of c-Si wafer surface conditions very well. We carried out that the deposition of high quality hydrogenated silicon amorphous thin films by RF-PECVD systems having high density and low crystallinity which are results of effective medium approximation modeling and fitting using spectroscopic ellipsometer. We reached the cell efficiency 12.67% and 14.30% on flat and textured CZ c-Si wafer each under AM1.5G irradiation, adopting the optimized cleaning and deposition conditions that we made. As a result, we confirmed that spectroscopic ellipsometry is very useful analyzing methode for hetero-junction solar cells which need to very thin and high quality multi layer structure.

• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.207-212
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• 2014

Aluminum-doped zinc oxide (AZO) films were deposited on SiOC/Si wafer by an RF-magnetron sputtering system, by varying the deposition parameters of radio frequency power from 50 to 200 W. To assess the correlation of the optical properties between the substrate and AZO thin film, photoluminescence was measured, and the origin of deep level emission of AZO thin films grown on SiOC/Si wafer was studied. AZO formed on SiOC/Si substrates exhibited ultraviolet emission due to exciton recombination, and the visible emission was associated with intrinsic and extrinsic defects. For the AZO thin film deposited on SiOC at low RF-power, the deep level emission near the UV region is attributed to an increase of the variations of defects related to the AZO and SiOC layers. The applied RF-power influenced an energy gap of localized trap state produced from the defects, and the gap increased at low RF power due to the formation of new defects across the AZO layer caused by lattice mismatch of the AZO and SiOC films. The optical properties of AZO films on amorphous SiOC compared with those of AZO film on Si were considerably improved by reducing the roughness of the surface with low surface ionization energy, and by solving the problem of structural mismatch with the AZO film and Si wafer.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.660-665
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• 2002

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of grinding wheel in the in-feed machining method. In this study, grinding experiments by the rotary surface grinding machine with straight type wheels ware conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding n/c equipment with an ELID wit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2 - 6 nm in Ra.

• 반도체디스플레이기술학회지
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• 제2권3호
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• pp.1-6
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• 2003

In the rapid changes of the semiconductor manufacturing technologies for early 21st century, it may be safely said that a kernel of terms is the size increase of Si wafer and the size decrease of semiconductor devices. As the size of Si wafers increases and semiconductor device is miniaturized, the units of cleaning processes increase. A present cleaning technology is based upon RCA cleaning which consumes vast chemicals and ultra pure water (UPW) and is the high temperature process. Therefore, this technology gives rise to environmental issue. To resolve this matter, candidates of advanced cleaning processes have been studied. One of them is to apply the electrolyzed water. In this work, electrolyzed water cleaning was compared with various chemical cleaning, using Si wafer surfaces by changing cleaning temperature and cleaning time, and especially, concentrating upon the contact angle. It was observed that contact angle on surface treated with Electrolyzed water cleaning was $4.4^{\circ}$ without RCA cleaning. Amine series additive of high pKa (negative logarithm of the acidity constant) was used to observe the property changes of cathode water.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.127-134
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• 2001

Nano adhesion and friction between a Sj$_3$N$_4$ AFM tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes in various ranges of normal load. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and Si-wafer of different surface roughness were used. Results showed that nano adhesion and friction decreased as the surface roughness increased. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the normal load was low.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.63-67
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• 2008

전자산업의 소형화와 경량화 추세에 맞추어 최근 집적 칩(IC)이나 패키지를 적층시키는 삼차원 집적화(3D integration) 기술 개발은 차세대 핵심기술로 중요시되고 있다. 본 연구에서는 삼차원 집적화 공정 기술 중 하나인 초박막 실리콘 웨이퍼 연삭(grinding)공정이 웨이퍼 표면에 미치는 영향에 대해서 조사하였다. 실리콘 웨이퍼를 약 $30{\mu}m$과 $50{\mu}m$ 두께까지 연삭한 후, 미세연삭(fine grinding) 단계까지 처리된 시편을 건식 연마(dry polishing) 또는 습식 애칭(wet etching)으로 표면 처리된 시편들과 비교 분석하였다. 박막 웨이퍼 두께는 전계방시형 주사전자현미경과 적외선 분광기로 측정하였고, 표면 특성 분석을 위해선 표면주도(roughness), 표면손상(damage), 경도를 원자현미경, 투과정자현미경 그리고 나노인덴터(nano-indentor)를 이용하여 측정하였다. 표면 처리된 시편의 특성이 표면 처리되지 않은 시편보다 표면주도와 표면손상 등에서 현저히 우수함을 확인 할 수 있었으나, 경도의 경우 표면 처리의 유무에 관계없이 기존의 벌크(bulk)실리콘 웨이퍼와 오차범위 내에서 동일한 것으로 보였다.