Purification of metallurgical‐grade silicon up to solar grade

Yuge, Noriyoshi; Abe, Mitsunobu; Hanazawa, Kazuhiro; Baba, Hiroyuki; Nakamura, N.; Kato, Yoshiei; Sakaguchi, Y.; Hiwasa, Shoichi; Aratani, Fukuo

doi:10.1002/pip.372

Cited by 148 publications

(78 citation statements)

References 2 publications

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“…They concluded that the highest water vapor pressure, 1.24 vol.% H 2 O, has the highest apparent rate constant for boron removal. Similar experiments were carried out by Nakamura et al 7 and Yuge et al 8 Recently, Wu et al 10 reported their experimental results for the removal of boron by an Ar-H 2 O-O 2 mixture. Boron was reduced from 18 ppm to 2 ppm after the first 10 min.…”

Section: Introductionsupporting

confidence: 68%

“…A comparison of the apparent mass transfer coefficients between the current work and those of steam-added plasma melting processes [5][6][7][8] is shown in Fig. 3.…”

Section: Discussionmentioning

confidence: 99%

“…Several processes have been reported for this purpose. Molten flux treatment [1][2][3][4] and plasma [5][6][7][8][9][10][11] are two of the most common methods for the removal of boron in silicon. Although the molten flux treatment can effectively remove boron, it will inevitably contaminate the silicon feedstock.…”

Section: Introductionmentioning

confidence: 99%

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Removal of Boron in Silicon by H2-H2O Gas Mixtures

Tang

Andersson

Nordstrand

et al. 2012

JOM

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The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52 ppm initially to 0.7 ppm and 3.4 ppm at 1450°C and 1500°C, respectively, after blowing a H 2 -3.2%H 2 O gas mixture for 180 min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.

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Section: Introductionsupporting

confidence: 68%

“…A comparison of the apparent mass transfer coefficients between the current work and those of steam-added plasma melting processes [5][6][7][8] is shown in Fig. 3.…”

Section: Discussionmentioning

confidence: 99%

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Removal of Boron in Silicon by H2-H2O Gas Mixtures

Tang

Andersson

Nordstrand

et al. 2012

JOM

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“…The removal of B from silicon by gas treatment has been studied by several researchers using plasma technique or gas blowing. The application of H 2 O gas in the reactive gas in plasma refining [1][2][3][4][5][6] and H 2 -H 2 O gas mixtures through non-plasma-aided gas blowing [7,8] has shown faster B removal compared to the application of pure H 2 , [8][9][10] O 2 , [9,11] and CO 2 [11] as reactive gases. The plasma refining experiments with H 2 -O 2 mixtures [12,13] as the reactive gas have also indicated faster B removal from silicon than using H 2 , O 2 , CO 2 gases.…”

Section: Introductionmentioning

confidence: 99%

Boron Removal from Silicon by Humidified Gases

Safarian

Tang

Hildal³

et al. 2014

Metallurgical and Materials Transactions E

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Boron (B) is one of the most problematic impurities to remove from metallurgical grade silicon in the production of more pure solar grade silicon (SoG-Si). In the present work, recent progresses in the application of reactive gases for B removal from molten silicon is reviewed. Moreover, in order to clarify the mechanisms and kinetics of gas-based B-refining, an experimental procedure using humidified Ar, N 2 , and H 2 gases applied to boron-doped silicon melt is described. It is shown that the kinetics and extent of B removal is depending on the type of humidified gas. The thermodynamics and kinetics of B removal from molten silicon are studied to explain experimental observations. The mass transfer coefficients of B are calculated and possible mechanisms for B removal by the reactive gases are proposed:It is shown that the lower equilibrium partial pressure of HBO gas at higher temperatures causes slower B removal rate.

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“…They try to upgrade the metallurgical silicon through a combination of steps suited for the different impurities. For example, by directional solidification they take advantage of the high liquid-solid segregation coefficient of metallic impurities; by leaching they eliminate metallic suicides in the grain boundaries; by slagging, gas blowing, evaporation and plasma torch they try to reduce the concentration of boron and/or phosphorus;... [11] [12] [13].…”

Section: Applying Typical Steps From Metallurgical Refinementmentioning

confidence: 99%

Ultrapurification of Silicon for Photovoltaic Applications

Cañizo

Coso

Ĺuque

2010

Advances in Science and Technology

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Abstract. The recent explosive growth of Photovoltaics and the relative avidity for silicon of the predominant solar cell technology have resulted in a dramatic change of the polysilicon industry structure. While in the past the polysilicon was manufactured almost exclusively for the semiconductor industry, now more than half of the market is devoted to the solar industry. The different alternative routes to purify silicon for photovoltaic applications are presented in the paper, analysing their advantages and drawbacks. Emphasis is made on the CENTESIL initiative, a new private-public partnership venture promoting a pilot plant that is in an advanced state of construction. The goal is to allow the photovoltaic companies worldwide to count with an independent research centre to help them to establish their own polysilicon plant.

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Purification of metallurgical‐grade silicon up to solar grade

Cited by 148 publications

References 2 publications

Removal of Boron in Silicon by H2-H2O Gas Mixtures

Removal of Boron in Silicon by H2-H2O Gas Mixtures

Boron Removal from Silicon by Humidified Gases

Ultrapurification of Silicon for Photovoltaic Applications

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