Influence of reaction between silica crucible and graphite susceptor on impurities of multicrystalline silicon in a unidirectional solidification furnace

Gao, Bing; Nakano, Satoshi; Kakimoto, Koichi

doi:10.1016/j.jcrysgro.2010.12.006

Cited by 31 publications

(13 citation statements)

References 14 publications

(31 reference statements)

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“…The considered reaction equilibrium constant is as follows:

K = \frac{a_{S i O (g)}^{3} a_{C O (g)}}{a_{S i C (s)} a_{S i O_{2} (s)}^{2}} = e^{- Δ G_{0} / R T} .

Owing to the different melting points between silica [

S i O_{2} (s)

] and

S i C (s)

S i O_{2} (s)

can be approximately considered as a solvent and SiC atoms from the deposition of the graphite susceptor can be approximately regarded as a solute inside the

S i O_{2} (s)

solvent. Assuming that sufficient amounts of

S i O_{2} (s)

and

S i C (s)

are present, the activities of the species ( a ) are expressed as follows :

\begin{matrix} left a_{S i O_{2} (s)} = 1, a_{S i C (s)} = c_{S i C (s)} / c_{S i O_{2} (s)}, \\ left a_{S i O (g)} = \frac{P_{S i O (g)}}{101, 325 P a}, a_{C O (g)} = \frac{P_{C O (g)}}{101, 325 P a}, \end{matrix}

where

c_{S i O_{2} (s)}

and

…”

Section: Developments Of Transport and Chemical Modelsmentioning

confidence: 99%

“…First, the origins of CO and the relevant chemical reactions at high temperatures must be identified to enable the development of approaches that effectively reduce the C content. Several reactions contribute to the incorporation of C, including graphite etching, crucible contact, silicon carbide (SiC) deposition, and SiC coating . A greater concern, in particular, is that these reactions are generally triggered during the preheating and melting stages.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Development of carbon transport and modeling in Czochralski silicon crystal growth

Liu

Nakano

Kakimoto

2016

Crystal Research and Technology

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In Czochralski silicon (CZ-Si) crystal growth, species generated from high temperature reactions and transported by Si melt and argon (Ar) gas strongly affect the purity and quality of the grown crystals. The reduction of carbon (C) contamination in crystal is required for producing Si wafers with long carrier lifetimes. Advances in the modeling of C contamination in CZ-Si growth are reviewed on the basis of the mass transport phenomena in the Ar gas and Si domains. The generation, incorporation, and accumulation of C were investigated by the transient global simulations of heat and mass transport during the melting process of CZ-Si growth. In addition to graphite etching, two additional sources of carbon monoxide (CO) were analyzed according to their contributions to the accumulation of C in the Si melt. The effect of gas flow control on the back diffusion of the generated CO was examined via a parametric study of the furnace pressure and the Ar gas flow rate. Strategies for C content reduction are discussed on the basis of the mechanisms of C accumulation, which indicate that the final C content depends on both the growth duration as well as the flux of contaminants at the gas/melt interface.

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“…The considered reaction equilibrium constant is as follows:

K = \frac{a_{S i O (g)}^{3} a_{C O (g)}}{a_{S i C (s)} a_{S i O_{2} (s)}^{2}} = e^{- Δ G_{0} / R T} .

Owing to the different melting points between silica [

S i O_{2} (s)

] and

S i C (s)

S i O_{2} (s)

can be approximately considered as a solvent and SiC atoms from the deposition of the graphite susceptor can be approximately regarded as a solute inside the

S i O_{2} (s)

solvent. Assuming that sufficient amounts of

S i O_{2} (s)

and

S i C (s)

are present, the activities of the species ( a ) are expressed as follows :

\begin{matrix} left a_{S i O_{2} (s)} = 1, a_{S i C (s)} = c_{S i C (s)} / c_{S i O_{2} (s)}, \\ left a_{S i O (g)} = \frac{P_{S i O (g)}}{101, 325 P a}, a_{C O (g)} = \frac{P_{C O (g)}}{101, 325 P a}, \end{matrix}

where

c_{S i O_{2} (s)}

and

…”

Section: Developments Of Transport and Chemical Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of carbon transport and modeling in Czochralski silicon crystal growth

Liu

Nakano

Kakimoto

2016

Crystal Research and Technology

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“…Results of experimental and theoretical analyses suggest that the main reason might be reaction between the silica crucible and the graphite susceptor supporting the crucible. 25 To further investigate this discrepancy, theoretical and numerical investigations have been carried out to determine the influence of the crucible 3.0x10 +17 1.5x10 +17 00x10 +00 www.tms.org/jom.html reaction on carbon and oxygen impurities within multicrystalline silicon in a unidirectional solidification furnace. Figure 5a shows an enlarged figure of CO concentration distribution near the touching corner between the silica crucible and the graphite susceptor shown in Figure 1.…”

Section: Effect Of Crucible Reaction With Susceptor On Impuritiesmentioning

confidence: 99%

Reducing impurities of multicrystalline silicon in a unidirectional solidification furnace for solar cells

Gao

Nakano

Kakimoto

2011

JOM

Self Cite

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How would you……describe the overall significance of this paper? This paper proposed some methods to reduce the impurities of carbon and oxygen during the production of multicrystalline silicon. Therefore, high-quality and high-efficiency multicrystalline silicon can be obtained by the present solutions.…describe this work to a materials science and engineering professional with no experience in your technical specialty? We theoretically analyzed the incorporation mechanism of impurities of carbon and oxygen, and proposed to use a crucible cover to effectively reduce the carbon and oxygen impurities. Impurities can be further reduced if a reaction between the crucible and the graphite susceptor is prohibited.…describe this work to a layperson? Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and because of the relative high conversion efficiency of solar cells made from this material. The impurities of carbon and oxygen can markedly damage the quality and conversion efficiency of multicrystalline silicon. This paper mainly deals with the purification of carbon and oxygen impurities during production.Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and the relative high conversion efficiency of solar cells made from this material. Effective control of carbon and oxygen impurities in the crystal is required for the production of a high-quality component. In order to reduce impurity levels in a unidirectional solidification furnace, it is proposed to add a crucible cover to the casting process. Results from numerical simulations indicate a marked reduction of carbon impurity in a multicrystalline silicon ingot. The effect of crucible cover material on impurities in multicrystalline silicon was also investigated. These results show that the carbon concentration within the silicon ingot can be reduced by 10 times if the cover is made from carbon and by 1,000 times if the cover is made from tungsten. These results show that an effective and economical method for designing a cover is to use carbon and deposit a thin layer of tungsten on it. Experimental tests have also been carried out by placing a tungsten cover above the crucible. Results indicated that the carbon impurity has significantly decreased; however, the measured carbon concentration in the crystal is larger than the theoretically predicted value, despite the use of a crucible cover. A theoretical analysis has shown that this difference is due to a reaction between the crucible and the graphite susceptor. Furthermore, global simulations have shown that this reaction has a marked effect on carbon and oxygen impurities. When the carbon activity on the surface of the graphite susceptor increases, both oxygen and carbon impurities in crystal increase rapidly. Therefore, the production of high-purity multicrystalline silicon can be improved by designing a crucible cover with a thin layer of tungsten on it and by setting a fr...

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“…The use of Si: Ni in annealing technology is of great interest to nickel impurities in monocrystalline silicon and their use for the manufacture of thermistors. The widespread use of Ni as a dopant as an alternative to expensive gold in the production of high-speed highly sensitive structures [1], [2]. Moreover, there are applications of alloying methods in industry, such as laser technology to change processing speed [3], effects of heat transfer on float glass surface [4] and so on.…”

Section: Introductionmentioning

confidence: 99%

Electrophysical properties of Silicon doped by Nickel impurity using Diffusion method

Utamuradova¹

2020

IJETER

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Silicon is a mature material, but it is still unique for its crucial role in the microelectronic and photovoltaic sectors. Despite the vast knowledge accumulated on silicon and their alloys, this material still demands research. In this paper, the conductivity and lifetime of non equilibrium charge carriers of nickel impurities in single-crystal silicon are determined. The electrophysical properties for the silicon single crystals doped with nickel impurity by establishing optimal diffusion mode were studied with the Hall effect method and the standard method in constant electric and magnetic fields. It is shown that the generation of thermal donors is suppressed by the interaction of nickel and oxygen impurities introduced at 500 ° C, and it is proved that it does not affect the formation of high-temperature thermal donors formed at 700 ° C.

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Influence of reaction between silica crucible and graphite susceptor on impurities of multicrystalline silicon in a unidirectional solidification furnace

Cited by 31 publications

References 14 publications

Development of carbon transport and modeling in Czochralski silicon crystal growth

Development of carbon transport and modeling in Czochralski silicon crystal growth

Reducing impurities of multicrystalline silicon in a unidirectional solidification furnace for solar cells

Electrophysical properties of Silicon doped by Nickel impurity using Diffusion method

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