JP2010100508A - Production method of high purity silicon - Google Patents
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本発明は、金属シリコン原料から、高純度シリコンを製造する方法に関するものである。 The present invention relates to a method for producing high-purity silicon from a metal silicon raw material.
太陽電池に用いられるシリコンの純度は、通常６Ｎ以上、７Ｎ程度の高純度が要求されている。通常の金属シリコン原料の純度は通常９７〜９９．９％程度であるため、太陽電池に使用するには、これを要求される純度まで不純物を除去して高純度化の精錬が必要である。 The purity of silicon used for solar cells is usually required to be as high as 6N or more and about 7N. Since the purity of a normal metal silicon raw material is usually about 97 to 99.9%, in order to use it for a solar cell, it is necessary to refine impurities by removing impurities to the required purity.
従来の、冶金的精錬方法による金属シリコン原料の高純度化の方法は、▲１▼真空溶融法による不純物の気化分離、▲２▼酸素・水蒸気添加溶融法によるＢの分離、▲３▼一法凝固法によるＡｌ、Ｔｉ、Ｆｅの分離などによる不純物除去の高純度化法が提唱されている。またこれらの方法の組み合わせた高純度化法も提案されており、純度が６Ｎ程度のシリコンついて製造が試みられている。 Conventional methods for purifying metal silicon raw materials by metallurgical refining methods are: (1) impurity vaporization separation by vacuum melting method, (2) B separation by oxygen / steam addition melting method, (3) one method A high-purity method for removing impurities by separating Al, Ti, and Fe by a solidification method has been proposed. A high-purity method combining these methods has also been proposed, and production of silicon having a purity of about 6N has been attempted.
本発明は、金属シリコンの高純度化に当たり、従来のシリコンの精製方法では、ホウ素、リン、鉄、チタンなどの不純物成分の除去が不十分であり、６〜７Ｎ以上の高純度化シリコンを安定して製造することは困難であった。また工程が長いためシリコンが蒸発してシリコンの収率やエネルギー消費の増加、過大な設備費用等より製造コストの増大が問題であった。本発明は、上記問題点を解決し、安価かつ品質が安定した高純度シリコンの製造方法を提供することを目的とする。 In the present invention, when purifying metal silicon, conventional silicon purification methods do not sufficiently remove impurity components such as boron, phosphorus, iron, titanium, and stabilize highly purified silicon of 6-7N or more. It was difficult to manufacture. In addition, since the process is long, the silicon is evaporated, which increases the production cost due to an increase in the yield of silicon, energy consumption, excessive equipment costs, and the like. An object of the present invention is to solve the above-mentioned problems and to provide a method for producing high-purity silicon that is inexpensive and stable in quality.
本発明の第１発明は、真空雰囲気、不活性ガスや酸化雰囲気などのガス雰囲気での溶融処理において、従来は少なくとも２基以上の異なる溶融炉が必要であったが、本発明では１基の溶融炉において、アーク方式、電磁誘導方式、プラズマ方式、電子ビーム方式等の２種以上の加熱装置を有することにより、１基の溶融炉において金属シリコンを溶融させた後、真空状態での真空処理及び、異なるガス雰囲気での酸化処理、還元処理を行うができることにより原料シリコンに含まれる不純物を効率的に除去できることを見出した。 In the first invention of the present invention, at least two different melting furnaces have been conventionally required in the melting treatment in a gas atmosphere such as a vacuum atmosphere, an inert gas or an oxidizing atmosphere. In a melting furnace, by having two or more types of heating devices such as an arc method, an electromagnetic induction method, a plasma method, an electron beam method, etc., after melting metal silicon in one melting furnace, vacuum processing in a vacuum state And it discovered that the impurity contained in raw material silicon | silicone could be removed efficiently by being able to perform the oxidation process and reduction process in a different gas atmosphere.
本発明の第２発明は、１基の溶融炉において金属シリコンの溶解・精錬において、真空処理工程、酸浸出処理工程、還元処理工程を行うにあたり、これらの処理操作を単独ではなく、組み合わせて繰り返して行うことにより不純物の除去が促進されて、高純度のシリコンが得ることができる。 In the second invention of the present invention, when performing a vacuum treatment step, an acid leaching treatment step, and a reduction treatment step in melting and refining metal silicon in a single melting furnace, these treatment operations are not combined but repeated in combination. As a result, removal of impurities is promoted, and high-purity silicon can be obtained.
本発明の第３発明は、一基の溶融炉において溶融した金属シリコンを真空処理及び、酸化処理、還元処理を組み合わせて不純物除去の処理を行うに当たり、金属シリコンを前処理として酸浸出処理を行うことにより、出発原料に低品位の金属シリコンを使用することが出来、またシリコンの溶融状態での真空処理、酸化処理、還元処理等の気相処理での不純物除去を効率的に行うことができる。 In the third invention of the present invention, when metal silicon melted in a single melting furnace is subjected to impurity removal treatment by combining vacuum treatment, oxidation treatment, and reduction treatment, an acid leaching treatment is performed using metal silicon as a pretreatment. As a result, low-grade metallic silicon can be used as a starting material, and impurities can be efficiently removed in vapor phase processing such as vacuum processing, oxidation processing, and reduction processing in a molten state of silicon. .
本発明の第４発明は、金属シリコンを真空処理及び、酸化処理、還元処理を組み合わせて不純物除去の処理を行った後、一方向凝固処理を組み合わせて行うことにより金属シリコンに残存する不純物を効率的に分離できることを見出した。 According to the fourth aspect of the present invention, the impurities remaining in the metal silicon are efficiently treated by combining the unidirectional solidification process after performing the impurity removal process by combining the vacuum process, the oxidation process, and the reduction process on the metal silicon. It was found that it can be separated.
以上に述べたように、本発明の高純度シリコンの製造方法は、１基の溶融装置で効率よく不純物の除去が可能なことより、低品位のシリコン原料を用いることができ、また設備費用及び電力消費量の低減ができる。このようなことから太陽光発電に求められている高純度シリコンを安価に安定して製造することが可能になる。このようなことから本発明は、クリーンエネルギーである太陽光発電の発展に寄与することができ、また昨今、世界的な課題になっているエネルギー資源の節減にも貢献できる。 As described above, the high-purity silicon production method of the present invention can use a low-quality silicon raw material because impurities can be efficiently removed with a single melting apparatus, and equipment costs and Power consumption can be reduced. For this reason, it is possible to stably manufacture high-purity silicon required for photovoltaic power generation at low cost. For these reasons, the present invention can contribute to the development of photovoltaic power generation, which is clean energy, and can also contribute to the reduction of energy resources, which has become a global issue in recent years.
金属シリコンの高純度化法としては、四塩化ケイ素を中間体とした気相法、シリカを中間体とした化学的方法、金属シリコンを扱う冶金精錬法等が提唱されているが、本発明は、冶金精錬法に係わるものである。 As a method for purifying metal silicon, a gas phase method using silicon tetrachloride as an intermediate, a chemical method using silica as an intermediate, a metallurgical refining method using metal silicon, and the like have been proposed. It is related to the metallurgical refining method.
従来の冶金精錬法では、溶融したシリコンを真空処理、酸浸出処理、還元処理等の不純物の気化処理を行うことによりシリコンの高純度化を行うことが提唱されているが、真空処理、酸化処理、還元処理等の工程毎に溶融炉を変えていたため、溶融炉の設備費の増大、溶融シリコンの移送に伴うエネルギー損失、操作が複雑になる等の問題を有していた。 In the conventional metallurgical refining method, it has been proposed to purify silicon by performing impurity vaporization treatment such as vacuum treatment, acid leaching treatment, and reduction treatment on molten silicon, but vacuum treatment and oxidation treatment are proposed. Since the melting furnace was changed for each process such as reduction treatment, there were problems such as an increase in the equipment cost of the melting furnace, energy loss accompanying the transfer of molten silicon, and complicated operation.
本発明では、一つの溶融炉で酸化処理、真空処理、還元処理、真空処理を行うので、溶融炉の設備費用とエネルギー消費量を少なくすることが出来、また不純物を効率よく除去できることから低品位のシリコン原料を使用することができる。 In the present invention, since oxidation treatment, vacuum treatment, reduction treatment, and vacuum treatment are performed in a single melting furnace, the equipment cost and energy consumption of the melting furnace can be reduced, and impurities can be efficiently removed, so that the quality is low. The silicon raw material can be used.
本発明に用いる金属シリコンは、粉末、顆粒、チップ状、塊状などの形態のものを原料として使用することができる。原料の金属シリコンを溶融炉で真空処理、酸化処理、還元処理等の気相処理での不純物の除去を行う前に、前処理として金属シリコンを１ｍｍ以下の粒度に粉砕し、水でスラリー状にしてから硫酸、塩酸、硝酸等の鉱産を添加して酸浸出処理を行うことが好ましい。 The metal silicon used in the present invention can be used as a raw material in the form of powder, granules, chips, or lumps. Before removing impurities in the gas phase treatment such as vacuum treatment, oxidation treatment, reduction treatment, etc. in the melting furnace, the metal silicon is pulverized to a particle size of 1 mm or less as a pretreatment and made into a slurry with water. After that, it is preferable to carry out acid leaching treatment by adding minerals such as sulfuric acid, hydrochloric acid, nitric acid and the like.
この酸浸出処理で原料シリコンに含有するＦｅ、Ａｌ等の不純物を浸出・溶解することができる。このように前処理の酸浸出処理と前記の気相処理とを組み合わせると、原料の金属シリコンの純度は、９６％程度の低位品のものでも使用することができる。 Impurities such as Fe and Al contained in the raw material silicon can be leached and dissolved by this acid leaching treatment. Thus, when the acid leaching treatment in the pretreatment and the gas phase treatment are combined, the purity of the raw material metal silicon can be about 96%.
本発明では、高純度シリコンの製造のための溶融装置が、一基の溶融炉においてアーク方式、電子ビーム方式、プラズマ方式、電磁誘導方式の加熱装置を備えており、真空処理並びに種々のガス雰囲気での酸化処理、還元処理等の気相処理を任意に組み合わせて不純物除去の精錬処理ができる。 In the present invention, a melting apparatus for producing high-purity silicon is equipped with a heating apparatus of an arc system, an electron beam system, a plasma system, and an electromagnetic induction system in a single melting furnace, and performs vacuum processing and various gas atmospheres. The refining treatment for removing impurities can be performed by arbitrarily combining gas phase treatments such as oxidation treatment and reduction treatment.
このように１基の溶融炉で、燐、ホウ素、炭素などの不純物を効率よく除去できることから、設備費用が軽減できるのみならず、別の溶融炉への高温の溶融シリココンの移送が無くなることから、操作が簡便となり、また冷却に伴うエネルギーロスを低減させることができる。 In this way, impurities such as phosphorus, boron, and carbon can be efficiently removed with one melting furnace, which not only reduces equipment costs, but also eliminates the transfer of high-temperature molten silicon to another melting furnace. The operation becomes simple and the energy loss accompanying cooling can be reduced.
本発明に用いる溶融炉の加熱方式としては、アーク方式、電気抵抗式、誘導方式、プラズマ式、電子ビーム方式等を組み合わせて用いることができるが、誘導加熱方式を基本として、これにプラズマ式、電子ビーム方式を組み合わせることが望ましい。誘導加熱方式の溶融炉としては、コイル一体型コールドクルーシブル方式の溶融炉が好ましい。この方式の溶融炉は、溶融したシリコンが容器と直接接触しないことから、容器からの不純物の混入が少なく、また容器の耐久性が高いことより高純度化に使用する溶融炉として好ましい。 As a heating method of the melting furnace used in the present invention, an arc method, an electric resistance method, an induction method, a plasma method, an electron beam method, etc. can be used in combination, but based on the induction heating method, a plasma method, It is desirable to combine the electron beam method. As the induction heating type melting furnace, a coil-integrated cold crucible type melting furnace is preferable. This type of melting furnace is preferable as a melting furnace used for high purity because molten silicon is not in direct contact with the container, so that impurities are not mixed from the container and the durability of the container is high.
コイル一体型コールドクルーシブル溶融炉は、加熱初期において金属シリコンの抵抗値が高いことから加熱速度が遅いことと、雰囲気ガスとの接触性が悪いことが問題である。この対策としてプラズマ方式、電子ビーム方式の加熱方式を組み合わせることが好ましい。これにより加熱速度の向上、雰囲気ガスとの接触の改善、消費エネルギーの削減、生産性の向上を図ることができる。 The coil-integrated cold crucible melting furnace has a problem in that the resistance value of metal silicon is high in the initial stage of heating, so that the heating rate is slow and the contact property with the atmospheric gas is poor. As a countermeasure, it is preferable to combine a plasma method and an electron beam method. Thereby, the improvement of a heating rate, the improvement of contact with atmospheric gas, the reduction of energy consumption, and the improvement of productivity can be aimed at.
また、本発明における溶融炉における溶解・精錬の手順は、先ずは原料シリコンを溶融炉内の容器に原料シリコンを投入し、アルゴン、ヘリウム等の不活性ガスを送入し、炉室内を不活性ガス雰囲気にして溶融する。 The melting and refining procedures in the melting furnace according to the present invention are as follows. First, raw silicon is introduced into a container in the melting furnace, an inert gas such as argon or helium is introduced, and the furnace chamber is inert. Melt in a gas atmosphere.
溶融した金属シリコンは、１基の溶融炉において誘導方式で加熱・保持すると共に、プラズマ方式や電子ビーム方式で加熱を並行的に行いながら、酸化処理、還元処理、真空処理を行う。 The molten metal silicon is heated and held by an induction method in one melting furnace, and is subjected to oxidation treatment, reduction treatment, and vacuum treatment while being heated in parallel by a plasma method or an electron beam method.
以下、酸化処理、還元処理、真空処理について述べる。 Hereinafter, oxidation treatment, reduction treatment, and vacuum treatment will be described.
酸化処理の操作手順は、プラズマトーチにアルゴン、ヘリウム等の不活性ガスに酸素や水蒸気を添加したガスを導入し、高温になったプラズマガスを溶融したシリコンの表面に吹き付けて行う。プラズマガスをシリコンの溶融面に吹き付けると溶融物が攪拌されて不純物の気化が促進される。この酸処理の温度は１５００〜１７００℃が好ましい。また、酸化雰囲気を形成するためのプラズマトーチへの導入ガスの組成としては、不活性ガス中の酸素の割合が０．０００〜０．１％、水蒸気が０．１〜１０ＶＯＬ％で行うことが好ましい。 The operation procedure of the oxidation treatment is performed by introducing a gas obtained by adding oxygen or water vapor to an inert gas such as argon or helium into a plasma torch, and spraying the plasma gas at a high temperature onto the molten silicon surface. When plasma gas is blown onto the silicon melt surface, the melt is agitated to promote the vaporization of impurities. The acid treatment temperature is preferably 1500-1700 ° C. The composition of the gas introduced into the plasma torch for forming the oxidizing atmosphere is that the oxygen content in the inert gas is 0.000 to 0.1% and the water vapor is 0.1 to 10 VOL%. preferable.
還元処理の操作手順は、プラズマトーチにアルゴン、ヘリウム等の不活性ガスに水素やメタンガス、プロパンガス等の可燃性ガスを添加した混合ガスを導入し、高温になったプラズマガスを溶融したシリコンの表面に吹き付けて行う。プラズマガスをシリコンの溶融面に吹き付けると溶融物が攪拌されて不純物の気化が促進される。この還元処理の温度は１５００〜１７００℃が好ましい。また、還元雰囲気を形成するためのプラズマトーチへの導入ガスの組成としては、不活性ガス中の水素、可燃性ガスの割合が０．１〜５０ＶＯＬ％で行うことが好ましい。 The operating procedure of the reduction treatment is to introduce a mixed gas in which a combustible gas such as hydrogen, methane gas, or propane gas is added to an inert gas such as argon or helium into a plasma torch, and the molten plasma gas is melted. Spray on the surface. When plasma gas is blown onto the silicon melt surface, the melt is agitated to promote the vaporization of impurities. The reduction treatment temperature is preferably 1500 to 1700 ° C. The composition of the gas introduced into the plasma torch for forming the reducing atmosphere is preferably such that the ratio of hydrogen and combustible gas in the inert gas is 0.1 to 50 VOL%.
真空処理の手順は、また炉内への不活性ガスの送入を停止し、また真空ポンプを稼働させて炉室内を真空状態にする。炉室内の真空度は、１０−１〜１０−５ｔｏｒｒに保持して行う。溶融シリコンの加熱・保持は誘導方式でも良いが、電子ビーム方式と並行的に加熱を行うと、溶融シリコンが攪拌され、温度が均一となって不純物の気化蒸発が促進させることが出来る。処理時の真空度は、１０−１ｔｏｒｒより低いと不純物の気化が進み難く、また真空度が１０−５以上の高真空度になるとシリコンのロスが増大するので、真空度は１０−２〜１０−４ｔｏｒｒが特に好ましい。処理温度は１５００〜１７００℃が好ましい。In the vacuum processing procedure, the feeding of the inert gas into the furnace is stopped and the vacuum pump is operated to bring the furnace chamber into a vacuum state. The degree of vacuum in the furnace chamber is maintained at 10 −1 to 10 −5 torr. Although the induction method may be used for heating and holding the molten silicon, when the heating is performed in parallel with the electron beam method, the molten silicon is stirred, the temperature becomes uniform, and vaporization and evaporation of impurities can be promoted. When the degree of vacuum during processing is lower than 10 −1 torr, vaporization of impurities is difficult to proceed, and when the degree of vacuum is higher than 10 −5 , silicon loss increases, so the degree of vacuum is 10 −2 to 10 −4 torr is particularly preferred. The treatment temperature is preferably 1500-1700 ° C.
実際の金属シリコンに含まれる不純物の気化による高純度化の手順としては、上記の酸化処理、還元処理、真空処理を組み合わせ、繰り返して行う。例えば、溶融したシリコンを真空処理→酸化処理→真空処理→還元処理→真空処理のように組み合わせて処理することにより不純物の気化による除去を効率的に行うことができる。 As a procedure for increasing the purity by vaporizing impurities contained in actual metal silicon, the above oxidation treatment, reduction treatment, and vacuum treatment are combined and repeated. For example, it is possible to efficiently remove impurities by vaporizing by treating the molten silicon in a combination of vacuum treatment → oxidation treatment → vacuum treatment → reduction treatment → vacuum treatment.
前記の気相での不純物の除去処理を終えた溶融シリコンは、凝固室に移動させて一方向に凝固させることにより更に純度アップを図る。この一方向凝固処理を行うことにより、更に不純物の分離が除去され、金属シリコンの高純度化が可能となる。 The molten silicon that has been subjected to the impurity removal process in the gas phase is moved to the solidification chamber and solidified in one direction to further improve the purity. By performing this unidirectional solidification treatment, the separation of impurities is further removed, and the metal silicon can be highly purified.
この一方向凝固処理は、溶融シリコンを溶融炉から凝固精錬室の凝固容器に移送され、上部は加熱しながら底部から徐々に冷却することにより実施される。ゾーンメルティング効果によって、真空精錬、酸化精錬、還元処理で除去されなかった残存不純物がシリコン溶融体上部のスカルの中に残ることよりシリコンの純度アップが可能となる。 This unidirectional solidification treatment is performed by transferring molten silicon from a melting furnace to a solidification vessel in a solidification refining chamber, and gradually cooling the top from the bottom while heating. Due to the zone melting effect, residual impurities that have not been removed by vacuum refining, oxidation refining, and reduction treatment remain in the skull above the silicon melt, thereby improving the purity of silicon.
以下本発明の実施例について説明する。 Examples of the present invention will be described below.
本実施例に用いるシリコン原料としては、純度９８．０％の金属シリコンを１００メッシュ（目開き：０．５９ｍｍ）９９％以上程度の粒度に粉砕し、粉砕した金属シリコンを水でスラー状にして硫酸で酸浸出処理した後、水洗し、乾燥した。 As a silicon raw material used in this example, metal silicon having a purity of 98.0% is pulverized to a particle size of about 99% or more with 100 mesh (aperture: 0.59 mm), and the pulverized metal silicon is slurried with water. After acid leaching with sulfuric acid, it was washed with water and dried.
この酸浸出処理した粉状シリコンを溶融炉に供給し、不活性ガスを給装しながら誘導加熱を行いながら、さらにプラズマトーチを点火して加熱を行い、金属シリコンを不活性雰囲気中で溶融させた。金属シリコンの溶融面にプラズマトーチのガスを吹きつけ、金属シリコンの３０分間１６００℃に保持した。その後プラズマトーチを停止し、誘導加熱方式で１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施した。The powdered silicon subjected to the acid leaching treatment is supplied to a melting furnace, and induction heating is performed while supplying an inert gas. Further, the plasma torch is ignited and heated to melt the metal silicon in an inert atmosphere. It was. A plasma torch gas was blown onto the molten surface of the metal silicon, and the metal silicon was held at 1600 ° C. for 30 minutes. Thereafter, the plasma torch was stopped, and while maintaining the temperature at 1600 ° C. by induction heating, the gas in the furnace chamber was removed and the degree of vacuum was maintained at 10 −3 torr, and vacuum treatment was performed for 30 minutes.
次いで、炉室内に不活性ガスを送入し、プラズマトーチを点火し、溶融シリコンの温度を１６４０℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと酸素と水蒸気の混合ガスを送入し酸化処理を３０分間実施した。 Next, an inert gas is fed into the furnace chamber, the plasma torch is ignited, and a mixed gas of argon, oxygen, and water vapor is fed from the gas introduction tube of the plasma torch while maintaining the temperature of the molten silicon at 1640 ° C. The treatment was carried out for 30 minutes.
次いで、炉室内に不活性ガスを送入し、プラズマトーチを点火し１６４０℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと水素との混合ガスを送入し還元処理を３０分間実施した。 Next, an inert gas was fed into the furnace chamber, the plasma torch was ignited and maintained at 1640 ° C., and a mixed gas of argon and hydrogen was fed from the gas inlet tube of the plamas torch, and reduction treatment was performed for 30 minutes.
溶融したシリコンを凝固精錬室に移送し、上部をプラズマトーチで加熱しながら、一方向凝固させた。プラズマトーチを止め、金属シリコンの全体を完全に凝固させて、２００ｍｍφ×３００ｍｍＬのインゴットが得られた。冷却したインゴットは上部５０ｍｍを切り捨て、高純度シリコンのインゴットを得た。このインゴットについて不純物含有量の測定を行った。 The molten silicon was transferred to a solidification refining chamber and solidified in one direction while the upper part was heated with a plasma torch. The plasma torch was stopped and the entire metal silicon was completely solidified to obtain an ingot of 200 mmφ × 300 mmL. The cooled ingot was cut off at the top 50 mm to obtain a high purity silicon ingot. The impurity content of this ingot was measured.
原料シリコンは、実施例１と同じ方法で酸浸出処理した金属シリコンを出発原料とした。 The starting silicon was metal silicon that had been subjected to acid leaching treatment in the same manner as in Example 1.
この酸浸出処理した粉状シリコンを溶融炉に供給し、不活性ガスを給装しながら誘導加熱を行いながら、さらにプラズマトーチを点火して加熱を行い、金属シリコンを不活性雰囲気中で溶融させた。金属シリコンの溶融面にプラズマトーチのガスを吹きつけ、金属シリコンの３０分間１６４０℃に保持した。その後プラズマトーチを停止し、誘導加熱方式で１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施した。The powdered silicon subjected to the acid leaching treatment is supplied to a melting furnace, and induction heating is performed while supplying an inert gas. Further, the plasma torch is ignited and heated to melt the metal silicon in an inert atmosphere. It was. A plasma torch gas was blown onto the molten surface of the metal silicon, and the metal silicon was held at 1640 ° C. for 30 minutes. Thereafter, the plasma torch was stopped, and while maintaining the temperature at 1600 ° C. by induction heating, the gas in the furnace chamber was removed and the degree of vacuum was maintained at 10 −3 torr, and vacuum treatment was performed for 30 minutes.
次いで炉室内に不活性ガスを送入し、プラズマトーチを点火し、溶融シリコンの温度を１６００℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと酸素と水蒸気の混合ガスを送入し酸化処理を３０分間実施した。 Next, an inert gas is fed into the furnace chamber, the plasma torch is ignited, and a mixed gas of argon, oxygen, and water vapor is fed from the gas introduction pipe of the plasma torch while the temperature of the molten silicon is maintained at 1600 ° C. For 30 minutes.
次に炉室内に不活性ガスを送入し、プラズマトーチを点火し１６４０℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと水素との混合ガスを送入し還元処理を３０分間実施した。 Next, an inert gas was fed into the furnace chamber, the plasma torch was ignited and maintained at 1640 ° C., and a mixed gas of argon and hydrogen was fed from the gas inlet tube of the plamas torch, and reduction treatment was performed for 30 minutes.
次いでプラズマトーチを停止し、誘導加熱で溶融シリコンの温度を１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施した。Next, the plasma torch was stopped, and while the temperature of the molten silicon was maintained at 1600 ° C. by induction heating, the gas in the furnace chamber was removed and the degree of vacuum was maintained at 10 −3 torr, and the vacuum treatment was performed for 30 minutes.
このように処理した溶融シリコンは、実施例１と同じように一方向凝固法で冷却してシリコンのインゴットを得て不純物含有量の測定に供した。 The molten silicon thus treated was cooled by a unidirectional solidification method in the same manner as in Example 1 to obtain a silicon ingot, which was used for impurity content measurement.
原料シリコンは、実施例１と同じ方法で酸浸出処理した金属シリコンを出発原料とした。 The starting silicon was metal silicon that had been subjected to acid leaching treatment in the same manner as in Example 1.
この酸浸出処理した粉状シリコンを溶融炉に供給し、不活性ガスを給装しながら電磁誘導加熱を行いながらプラズマトーチで並行して加熱を行い、金属シリコンを不活性雰囲気中で溶融させた。溶融した金属シリコンのプラズマトーチのガスを吹きつけ、金属シリコンの３０分間１６４０℃に保持した。その後プラズマトーチを停止し、誘導加熱方式で１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施した。The powdered silicon subjected to the acid leaching treatment was supplied to a melting furnace, and heated in parallel with a plasma torch while performing electromagnetic induction heating while supplying an inert gas, thereby melting metal silicon in an inert atmosphere. . A gas of a molten metal silicon plasma torch was blown, and the metal silicon was held at 1640 ° C. for 30 minutes. Thereafter, the plasma torch was stopped, and while maintaining the temperature at 1600 ° C. by induction heating, the gas in the furnace chamber was removed and the degree of vacuum was maintained at 10 −3 torr, and vacuum treatment was performed for 30 minutes.
次いで、炉室内に不活性ガスを送入し、プラズマトーチを点火し、溶融シリコンの温度を１６００℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと酸素と水蒸気の混合ガスを送入し酸化処理を３０分間実施した。 Next, an inert gas is fed into the furnace chamber, the plasma torch is ignited, and a mixed gas of argon, oxygen, and water vapor is fed from the gas introduction tube of the plasma torch while the temperature of the molten silicon is maintained at 1600 ° C. The treatment was carried out for 30 minutes.
次にプラズマトーチを停止し、誘導加熱で溶融シリコンの温度を１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施しった。Next, the plasma torch was stopped, the temperature of the molten silicon was maintained at 1600 ° C. by induction heating, the gas in the furnace chamber was removed, and the degree of vacuum was maintained at 10 −3 torr, and the vacuum treatment was performed for 30 minutes.
次いで、炉室内に不活性ガスを送入し、プラズマトーチを点火し１６４０℃に保持しつつ、プラマストーチのガス導入管よりアルゴンと水素との混合ガスを送入し還元処理を３０分間実施した。 Next, an inert gas was fed into the furnace chamber, the plasma torch was ignited and maintained at 1640 ° C., and a mixed gas of argon and hydrogen was fed from the gas inlet tube of the plamas torch, and reduction treatment was performed for 30 minutes.
次にプラズマトーチを停止し、誘導加熱で溶融シリコンの温度を１６００℃に保持しつつ、炉室内のガスを除去して真空度を１０−３ｔｏｒｒに保持して真空処理を３０分間実施した。Next, the plasma torch was stopped, and while the temperature of the molten silicon was maintained at 1600 ° C. by induction heating, the gas in the furnace chamber was removed and the degree of vacuum was maintained at 10 −3 torr, and the vacuum treatment was performed for 30 minutes.
このように処理した溶融シリコンは、実施例１と同じように一方向凝固法で冷却してシリコンのインゴットを得て不純物含有量の測定に供した。 The molten silicon thus treated was cooled by a unidirectional solidification method in the same manner as in Example 1 to obtain a silicon ingot, which was used for impurity content measurement.
上記の実施例では、溶融シリコンについて不活性ガス処理、真空処理、酸化処理、還元処理の組み合わせの処理を実施したが、比較例では単独処理または組み合わせを欠如したプロセスで処理した。 In the above-described examples, a combination of inert gas treatment, vacuum treatment, oxidation treatment, and reduction treatment was performed on the molten silicon, but in the comparative example, the treatment was performed by a single treatment or a process lacking a combination.
実施例１と同じ方法で酸浸出処理した金属シリコンを出発原料に用い、実施例１と同じ装置と同じ方法によって不活性ガス送入中でシリコンを溶融させた後、不活性ガス中に酸素と水蒸気を混合し、酸化処理を実施した。このように処理した溶融シリコンは、実施例１と同じように一方向凝固法で冷却してシリコンのインゴットを得て不純物含有量の測定に供した。 Metal silicon that has been subjected to acid leaching treatment in the same manner as in Example 1 was used as a starting material, and silicon was melted in the inert gas feed by the same method as in Example 1, and then oxygen and oxygen were added to the inert gas. Steam was mixed and oxidation treatment was performed. The molten silicon thus treated was cooled by a unidirectional solidification method in the same manner as in Example 1 to obtain a silicon ingot, which was used for impurity content measurement.
実施例１と同じ方法で酸浸出処理した金属シリコンを出発原料に用い、実施例１と同じ装置と同じ方法によって不活性ガス送入中でシリコンを溶融させた後、真空処理を実施した。このように処理した溶融シリコンは、実施例１と同じように一方向凝固法で冷却してシリコンのインゴットを得て不純物含有量の測定に供した。 Metal silicon that had been subjected to acid leaching treatment by the same method as in Example 1 was used as a starting material, and the silicon was melted in the inert gas feed by the same method as in Example 1, followed by vacuum treatment. The molten silicon thus treated was cooled by a unidirectional solidification method in the same manner as in Example 1 to obtain a silicon ingot, which was used for impurity content measurement.
実施例１と同じ方法で酸浸出処理した金属シリコンを出発原料に用い、実施例１と同じ装置と同じ方法によって不活性ガス送入中でシリコンを溶融させた後、不活性ガス中に水素ガスを混合し、還元理を実施した。このように処理した溶融シリコンは、実施例１と同じように一方向凝固法で冷却してシリコンのインゴットを得て不純物含有量の測定に供した。 Metallic silicon leached by the same method as in Example 1 was used as a starting material, and after the silicon was melted in the inert gas feed by the same method as in Example 1, hydrogen gas was added into the inert gas. Were mixed and reduced. The molten silicon thus treated was cooled by a unidirectional solidification method in the same manner as in Example 1 to obtain a silicon ingot, which was used for impurity content measurement.
上記の実施例、比較例で得られたインゴットの不純物含有量の測定結果を表１に示す。 Table 1 shows the measurement results of the impurity content of the ingots obtained in the above Examples and Comparative Examples.
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| WO2010126067A1 (en) * | 2009-04-27 | 2010-11-04 | ユーエムケー・テクノロジー株式会社 | Silicon refining method and refining device |
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| WO2010126067A1 (en) * | 2009-04-27 | 2010-11-04 | ユーエムケー・テクノロジー株式会社 | Silicon refining method and refining device |
| JP5822393B2 (en) * | 2009-04-27 | 2015-11-24 | 森 竜平 | Method and apparatus for purifying silicon |
| CN101935041A (en) * | 2010-09-13 | 2011-01-05 | 大连隆田科技有限公司 | Method for extracting polysilicon through electron beams and acid washing |
| WO2012068717A1 (en) * | 2010-11-22 | 2012-05-31 | 矽明科技股份有限公司 | Method for manufacturing solar-grade silicon |
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