• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.222-222
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• 2010

수평성장 방식을 이용하여 다결정 실리콘 리본을 제조하였으며, 제조된 리본의 미세구조 및 결함을 분석하였다. 기존 잉곳 성장 및 절단 공정을 통해 제조된 실리콘 웨이퍼는 절단 중 실리콘의 손살 때문에 단가를 상승 시킨다. 따라서 실리콘 용탕으로부터 직접 웨이퍼를 제조하는 리본 기술이 활발히 연구되고 있다. 본 연구에서는 수명 성장 법을 이용하여 용융 실리콘으로부터 다결정 실리콘 리본을 제조 하였다. 제조 된 리본의 크기$50{\times}50$ mm였으며 두께는 $375{\pm}50{\mu}m$ 이었다. 또한, 미세구조 분석 결과 결정들의 형상이 불규칙적 이었으며, 바닥에서부터 윗부분까지 한 방향으로 성장되었다. 수직성장된 결정들의 평균 입경은 $50.2{\mu}m$ 이었다. 전위 (dislocations ), 이중(twins), 그리고 기공 (pores) 같은 구조적 결점들과 SiC, 탄소, 그러고 산소와 같은 불순물 결함 등이 관찰 되었다. 본 연구를 통해 제조된 다결정 실리콘 리본은 태양전지용 웨이퍼로 응용 가능 할 것으로 판단된다.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.1
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• pp.1-9
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• 2012

This paper explained about the sludge recycling system which retrieved the silicon and abrasive from solar cell wafer slicing. The basic process of the recycling system was multiple centrifuge and secondary processes of ultra sonic agitation, addition of alcohol-water solution and heating sludge was added for raising separation efficiency. The recycling rate was about 96% and 94% for 2N, 4N silicon respectively. The SiC abrasive recycling rate was about 80%. To retrieve the high purity of 4N silicon, the heat process in vacuum furnace was added to remove remaining impurity components.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.329-336
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• 2010

Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because a few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are the applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties after forging of hollow cast ingot were investigated from the experiment using circumferential sectional model. Also, the effects of process variables were studied by FEM simulation on the basis of thermo-visco-plastic constitutive equation. Applied strain is different at each position in length direction because diameter of hollow ingot is different in length direction. The different strain distribution become into a narrow gap by additional plastic deformation during diameter extension process.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.432-437
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• 2011

Recently, industry needs a new design of Czochralski(Cz) process for higher productivity with reasonable energy consumption. In this study, we carried out computational simulations for finding out a new optimal design of Cz process with variables which can be applied in real industry such as location of heater, shape of shield and crucible size. Objective process was Cz process which can be produced 8 inch diameter Si ingot for solar cell and we acquired an optimal design for higher productivity, low power consumption with stable production condition. For higher productivity we also change the crucible diameter from 22 inches to 24 inches with changing insulation thickness only because the process housing size could not be changed in industry.

• Particle and aerosol research
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• v.9 no.1
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• pp.31-36
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• 2013

In this study, Mo metal powder was prepared by hydrogen reduction of Mo trioxides with different purity of 2N and 3N grades. We have obtained Mo metal powder with oxygen content of 1450 ppm by hydrogen reduction and subsequent heat treatment for degassing. Using the Mo metal powder, a low-oxygen Mo ingot was prepared by repetitive vacuum arc melting. The oxygen content of the obtained Mo ingot was less than 70 ppm after vacuum arc melting for 30 min. The purity of the Mo metal powder and the ingot was evaluated using glow discharge mass spectrometry. The purity of the respective Mo ingots was increased to 3N and 4N grades from the Mo powder of 2N and 3N grades after the repetitive vacuum arc melting. The low oxygen Mo ingot thus can be used as a raw material for sputtering targets.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.147-151
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• 2005

실리콘 잉곳의 절단공정에서 발생하는 폐실리콘 슬러지는 실리콘과 실리콘카바이드 등의 유가자원이 함유되어 있는데, 본 연구에서는 폐실리콘 슬러지 중의 실리콘 분말을 효과적으로 분리, 회수하는 방법에 대해 검토하였다. 폐실리콘 슬러지는 상당량의 절삭유와 소량의 철분말이 포함되어 있는데 절삭유는 유기 용매에 용해시켜 효과적으로 분리하였고, 철분말은 자력선별에 의해 제거하였다. 절삭유와 철성분이 제거된 잔사인 실리콘과 실리콘 카바이드의 혼합 분말로부터 초음파 분산 선별법을 사용하여 실리콘 분말을 효율적으로 분리회수 하였다.

• Resources Recycling
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• v.30 no.1
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• pp.26-34
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• 2021

Titanium is the fourth most abundant structural metal, after aluminum, iron, and magnesium. However, it is classified as a 'rare metals', because it is difficult to smelt. In particular, the primary titanium production process is highly energy-intensive. Recycling titanium scraps to produce ingots can reduce energy consumption and CO2 emissions by approximately 95 %. However, the amount of metal recycled from scrap remains limited of the difficulty in removing impurities such as iron and oxygen from the scrap. Generally, high-grade titanium and its alloy scraps are recycled by dilution with a virgin titanium sponge during the remelting process. Low-grade titanium scrap is recycled to ferrotitanium (cascade recycling). This paper provides an overview of titanium production and recycling processes.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.25-32
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• 2011

We have studied on the slicing and polishing processes of R-plane sapphire wafers for the substrates of UHB nonpolar a-plane GaN LED. The fabrication conditions of the R-plane and c-plane wafers were influenced by the large anisotropic properties (mechanical properties) of the sapphire. The slicing process was more affected by the anisotropic properties of R-plane than the polishing process. When the slicing direction was $45^{\circ}$ to the a-flat, the slicing time was shorter and the quality of as-slicing wafers was better than the slicing direction of normal to the a-flat. The MRR(Material removal rate) of mechanical polishing processes such as lapping and DMP(Diamond mechanical polishing) did not show significant differences between the R-plane and c-plane. The MRR of the c-plane was about two times higher than that of R-planes at the CMP(Chemical mechanical polishing) process due to the formation of hydrolysis reaction layers on the surface of the c-plane.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.195-199
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• 2008

Production of the silicon feedstock for the semiconductor industry cannot meet the requirement for the solar cell industry because the production volume is too small and production cost is too high. This situation stimulates the solar cell industry to try the lower grade silicon feedstock like UMG (Upgraded Metallurgical Grade) silicon of 5$\sim$6 N in purity. However, this material contains around 1 ppma of dopant atoms like boron or phosphorous. Calculation of the composition profile of these impurities using segregation coefficient during crystal growth makes us expect the change of the type from p to n : boron rich area in the early solidified part and phosphorous rich area in the later solidified part of the silicon ingot. It was expected that the change of the growth speed during the silicon crystal growth is effective in controlling the amount of the metal impurities but not effective in reducing the amount of dopants.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.46.2-46.2
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• 2009

휴대전화, 랩톱 컴퓨터 등 각종 모바일기기 및 디스플레이 기기의 경박단소화 및 고기능화에 따라 연성회로기판(FPCB)의 사용량이 증가하고있다. 연성회로기판의 핵심소재인 동박적층필름(FCCL)은 폴리이미드필름과 접착층, Cu 층으로 구성되는데, 이 중접착층으로 사용되는 Ni-20Cr합금은 에칭공정 후 Cr의 잔류에 의해 불량률 증가가 문제되고 있어, Ni-Cr합금 스퍼터링 타깃의 Cr 함량 저감 또는 Cr-free Ni합금 개발 등이 요구되고 있다. 본 연구에서는 차세대 FCCL 본드층에 적합한 Ni기 합금을 개발하기 위한 기초연구로써 Cr 함량 및 가공열처리조건에 따른 미세조직과 집합조직 변화를 조사하였다. 4N급의 고순도Ni과 Cr을 진공 플라즈마 용해장치로 용해하여Ni-xCr (x=5, 10, 15, 20wt.%)합금 잉곳을 만들고, 이를 두께감소율 90%로 냉간압연한 후, $600^{\circ}C$ 및 $800^{\circ}C$에서 10~120분 동안 어닐링하여 시편을 준비하였다. 광학현미경으로 미세조직을 관찰하고, Micro-Vickers 경도시험을 통해 어닐링 조건에 따른 경도변화를 조사하였다. 또한 SEM-EBSD를 이용하여 집합조직 및 입계특성을 분석하였다. $600^{\circ}C$ 어닐링 시 Cr함량이 증가할수록 재결정 완료시간이 증가하여 Ni-20Cr합금의 경우 2시간이상 어닐링에도 재결정이 일어나지 않았다. $800^{\circ}C$ 어닐링 시 10분 어닐링 조건에서 4종류 합금 모두 재결정이 완료되었으며, 동일한 어닐링 조건에서 Cr함량이 증가할수록 결정립이 작아지는 것으로 나타났다. $800^{\circ}C$ 2시간 어닐링 조건에서 Ni-5Cr 합금의 주요 집합조직은 {223}<113>과 {122}<112>로 나타났으며, 이중 {223}<113>은Cr 함량이 증가함에 따라 점차 {122}<112>에 가까운 방향으로 변화되어 Ni-20Cr 합금의 경우 {123}<112>만이 형성되었다. 이러한 집합조직의 변화는 적층결함에너지 감소에 의한 ${\Sigma}3$ 입계의 분율 증가와 밀접한 관련이 있는 것으로 사료된다.