JPH10273313A - Production of polycrystal silicon ingot - Google Patents
Production of polycrystal silicon ingotInfo
- Publication number
- JPH10273313A JPH10273313A JP9077974A JP7797497A JPH10273313A JP H10273313 A JPH10273313 A JP H10273313A JP 9077974 A JP9077974 A JP 9077974A JP 7797497 A JP7797497 A JP 7797497A JP H10273313 A JPH10273313 A JP H10273313A
- Authority
- JP
- Japan
- Prior art keywords
- molten metal
- silicon
- ingot
- electron beam
- mold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
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- Silicon Compounds (AREA)
- Photovoltaic Devices (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、多結晶シリコン鋳
塊の製造方法に関し、特に、太陽電池用シリコンを製造
する過程において、金属シリコンから金属不純物元素を
除去した鋳塊を得る技術である。The present invention relates to a method for producing a polycrystalline silicon ingot, and more particularly to a technique for obtaining an ingot obtained by removing metal impurity elements from metallic silicon in a process of producing silicon for a solar cell.
【０００２】[0002]
【従来の技術】金属の純度を上げる技術の１つに、凝固
精製法がある。それは、精製対象の金属元素（ここで
は、シリコン）と除去対象の不純物元素（例えば、Ａ
ｌ，Ｐ，Ｃａ，Ｆｅ，Ｔｉ等）との間に成立している平
衡状態図を利用するものである。すなわち、ある濃度
（ｅ重量％）の不純物元素（Ｂ）を含む精製対象金属
（Ａ）の固相線と液相線とが図５に示すような関係にあ
る場合、不純物元素Ｂが、精製対象金属Ａの凝固時に固
相から液相に排出され、液相中に濃化する（液相中のＢ
の濃度は、ｅ点からｆ点へ、固相中のＢの濃度は、ｄ点
からｅ点へ移動）。具体的には、鋳造容器（以下、鋳型
という）内に保持した精製対象金属を、例えば底部から
上方へ一方向に向けて冷却、凝固すると、不純物濃度は
鋳塊の下方で低くなり、最後に凝固する液に濃縮され
る。従って、鋳塊の上部（濃縮部）を切断除去すれば、
純度の高い精製対象金属が得られることになる。2. Description of the Related Art One of the techniques for increasing the purity of a metal is a solidification refining method. It consists of a metal element to be purified (here, silicon) and an impurity element to be removed (for example, A
1, P, Ca, Fe, Ti, etc.). That is, when the solidus line and the liquidus line of the metal to be purified (A) containing a certain concentration (e wt%) of the impurity element (B) have a relationship as shown in FIG. When the target metal A solidifies, it is discharged from the solid phase to the liquid phase, and is concentrated in the liquid phase (B in the liquid phase).
(The concentration of B moves from point e to point f, and the concentration of B in the solid phase moves from point d to point e). Specifically, when the metal to be purified held in a casting vessel (hereinafter, referred to as a mold) is cooled and solidified, for example, in one direction upward from the bottom, the impurity concentration decreases below the ingot, and finally, It is concentrated to a coagulating liquid. Therefore, if the upper part (concentrated part) of the ingot is cut and removed,
A high-purity metal to be purified can be obtained.
【０００３】一方、近年、エネルギー源の多様化要求か
ら、太陽光発電が脚光を浴び、発電に必要な太陽電池用
シリコンの製造が盛んになったが、この発電を行うに
は、シリコン中の不純物元素を許容値以下に低減しなけ
ればならない。そのため、従来は、図６に示すように、
金属シリコンを塩酸と反応させてトリクロロ・シランと
してガス化し、該ガスを精留して不純物元素を除き、水
素ガスと反応させる所謂ＣＶＤ法でガスから析出させた
シリコンを用いていた。なお、この段階で析出したシリ
コンは、所謂イレブン・ナインと非常に高純度なので、
通常は半導体製造に利用できる。したがって、図６に示
す従来の製造方法は、せっかく半導体用にまで高純度に
したシリコンを、再度、太陽電池用に適するように成分
調整したり、精製や鋳造をしなければならないので、手
間がかかる上に、歩留が悪く、再溶解の設備、エネルギ
ーも別途必要で、製造費用が嵩むという問題があった。
そのため、現在入手可能な太陽電池は高価なものとな
り、一般的な普及の障害となっている。また、上記のよ
うな化学プロセスが主体の金属シリコンの精製では、シ
ラン、塩化物等の公害物質の多量発生が避けられず、量
産の障害になるという問題もあった。On the other hand, in recent years, photovoltaic power generation has been in the spotlight due to the demand for diversification of energy sources, and the production of silicon for solar cells required for power generation has been prosperous. Impurity elements must be reduced below acceptable values. Therefore, conventionally, as shown in FIG.
Metallic silicon is reacted with hydrochloric acid to gasify it as trichlorosilane, the gas is rectified to remove impurity elements, and silicon precipitated from the gas by a so-called CVD method of reacting with hydrogen gas has been used. The silicon deposited at this stage has a very high purity of so-called Eleven Nine,
Usually it can be used for semiconductor manufacturing. Therefore, in the conventional manufacturing method shown in FIG. 6, since silicon having been highly purified even for a semiconductor has to be adjusted again in a component suitable for a solar cell, or purified or cast, it is troublesome. In addition to this, there is a problem that the yield is poor, re-melting equipment and energy are separately required, and the production cost increases.
As a result, currently available solar cells are expensive and are an obstacle to their general spread. Further, in the purification of metallic silicon mainly based on the above-described chemical process, there is a problem that a large amount of pollutants such as silane and chloride is inevitably generated, which hinders mass production.
【０００４】そこで、本出願人は、上記のような化学プ
ロセスによる金属シリコンの高純度化を改め、冶金プロ
セスのみで太陽電池に適した純度のシリコンを製造し、
それを鋳造して一気にシリコン基板までにする方法（図
７参照）を検討している。そして、その一環として、上
記した凝固精製法を利用した金属シリコンの純度向上
を、図７に示す工程では２ケ所（粗凝固精製工程及び仕
上凝固精製工程）で採用して、金属シリコンが含有する
アルミニウム、鉄、チタニウム等の所謂金属不純物元素
を太陽電池用シリコンとしての目標値まで除去するよう
にしている。Therefore, the present applicant has improved the purification of metallic silicon by the above-described chemical process, and manufactured silicon having a purity suitable for solar cells only by a metallurgical process.
We are investigating a method (see FIG. 7) of casting it to a silicon substrate at once. As a part of this, the improvement of the purity of metallic silicon using the above-described solidification refining method is adopted in two places (coarse solidification purification step and finish solidification purification step) in the step shown in FIG. So-called metal impurity elements such as aluminum, iron, and titanium are removed to a target value as silicon for solar cells.
【０００５】ところで、この凝固精製を行うに際し、前
記切断除去する不純物元素の濃縮した部分をできるだけ
少なくすることが望ましい。理由は、シリコン歩留が向
上するからである。そこで、現在は、特開平５−１２４
８０９号公報に開示されているように、凝固末期に鋳型
の上方に設けた電子銃の出力を上げ、凝固した鋳塊の一
部を再溶解して、凝固精製をやり直すことが行われてい
る。また、国際公開番号、Ｗ／Ｏ９３／１２２７２１号
公報が開示したように、凝固途中で濃縮した残液を鋳型
外に流し出し、新しい溶融金属シリコンを追加して凝固
精製させ、シリコンの歩留を高める方法もある。さら
に、同公報は、電子ビームを溶湯面上でゆっくりと矩
形、円あるいはうず巻きの軌跡を描くように移動させ、
浮遊した不純物を該溶湯面上に集めるようにすること
が、開示されている。[0005] By the way, in performing the coagulation and refining, it is desirable to reduce as much as possible the concentrated portion of the impurity element to be cut and removed. The reason is that the silicon yield is improved. Therefore, at present, Japanese Patent Application Laid-Open No. 5-124
As disclosed in Japanese Unexamined Patent Publication No. 809, the output of an electron gun provided above a mold at the end of solidification is increased, a part of the solidified ingot is redissolved, and solidification purification is performed again. . In addition, as disclosed in International Publication No. W / O93 / 122721, the residual liquid concentrated during solidification is poured out of the mold, and new molten metal silicon is added to solidify and refine the silicon. There are ways to increase it. Further, the publication discloses that an electron beam is slowly moved on a molten metal surface so as to draw a locus of a rectangle, a circle or a spiral,
It is disclosed that suspended impurities are collected on the melt surface.
【０００６】しかしながら、特開平５−１２４８０９号
公報記載の「鋳塊の一部を再度溶解・凝固させる」方法
は、消費する電力が非常に大きくなり、安価な太陽電池
用シリコンの製造を目指す、本出願人にはなじめない。
また、前記Ｗ／Ｏ９３／１２２７２１号公報に記載の
「凝固途中で残液を排出する」方法は、操業を中断する
ため生産性が低下し、「不純物を浮遊させる」方法は、
本来の凝固精製の原理であり、大きな効果があるとは期
待できない。発明者は、太陽電池用シリコンを、従来よ
り半分以下のコストで製造することを目指しているが、
かかる従来の凝固精製を実施したのでは、その目標達成
はおぼつかない。However, the method of "dissolving and solidifying a part of an ingot again" described in Japanese Patent Application Laid-Open No. 5-124809 aims to produce inexpensive silicon for solar cells, which consumes a very large amount of electric power. Not familiar to the applicant.
Further, the method of “discharging the residual liquid during coagulation” described in the above-mentioned W / O93 / 122721 reduces the productivity because the operation is interrupted, and the method of “floating impurities” includes
This is the original principle of coagulation and refining and cannot be expected to have a significant effect. The inventor aims to produce silicon for solar cells at less than half the cost of conventional silicon,
If such a conventional coagulation refining is carried out, it is difficult to achieve the goal.
【０００７】[0007]
【発明が解決しようとする課題】本発明は、かかる事情
に鑑み、金属シリコンから金属不純物元素を従来より効
率良く除去した多結晶シリコン鋳塊の製造方法を提供す
ることを目的としている。SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a polycrystalline silicon ingot in which metal impurity elements are more efficiently removed from metal silicon than in the prior art.
【０００８】[0008]
【課題を解決するための手段】発明者は、上記目的を達
成するため、溶融金属の一方向凝固の基礎に立ち返って
研究し、以下の結論を得た。一般に、一方向凝固時の溶
融金属と凝固金属に含まれる不純物元素の分配は、下記
の所謂バートンの（１）式で表わされる。 ｋ＝ｋ0 ／｛ｋ0 ＋（１−ｋ0 ）・ｅｘｐ（−Ｒi ・δ／Ｄ）｝・・（１）式 ここで、 ＣS ： 凝固金属中のある不純物元素の濃度（重量％） ＣS ＝ｋ・Ｃ0 ｛１−（１−ｋ）・ｅｘｐ（−ｋｘ／
Ｌ）｝ Ｃ0 ： 溶融金属中のある不純物元素の初期濃度（重量
％） ｋ ： 実効分配係数（−） ｋ0 ： 平衡分配係数（−） Ｒi ： 凝固速度（ｃｍ／ｓｅｃ） δ ： 拡散層厚さ（ｃｍ） Ｄ ： 拡散係数（ｃｍ2 ／ｓｅｃ） ｘ ： 凝固金属の任意高さ（ｍｍ） Ｌ ： 鋳型内の溶融金属の深さ（ｍｍ） 一方向凝固を効率良く行うということは、実効分配係数
ｋを平衡分配係数ｋ0に近づけることである。それは、
（１）式において，δ、つまり液相側での不純物元素の
拡散層厚さを小さくし、それら元素の移動を早くすれば
可能となる。そこで、発明者は、この拡散層厚さを小さ
くする具体的な手段の発見に鋭意努力し、本発明を完成
させたのである。Means for Solving the Problems In order to achieve the above object, the inventor has returned to the basics of directional solidification of molten metal and studied and obtained the following conclusions. In general, the distribution of the molten metal and the impurity elements contained in the solidified metal during directional solidification is expressed by the following so-called Barton's formula (1). k = k 0 / {k 0 + (1-k 0) · exp (-R i · δ / D)} ·· (1) formula, where, C S: concentration of the impurity element with the coagulation metal (wt %) C S = k · C 0 ｛1− (1−k) · exp (−kx /
L)｝ C 0 : Initial concentration (weight%) of a certain impurity element in the molten metal k: Effective partition coefficient (−) k 0 : Equilibrium partition coefficient (−) R i : solidification rate (cm / sec) δ: Diffusion Layer thickness (cm) D: Diffusion coefficient (cm 2 / sec) x: Arbitrary height of solidified metal (mm) L: Depth of molten metal in mold (mm) To efficiently perform one-way solidification , The effective distribution coefficient k is close to the equilibrium distribution coefficient k 0 . that is,
In the equation (1), it becomes possible to reduce δ, that is, the thickness of the diffusion layer of the impurity element on the liquid phase side and to make the movement of these elements faster. Therefore, the inventor made an intensive effort to find a specific means for reducing the thickness of the diffusion layer, and completed the present invention.
【０００９】すなわち、本発明は、溶融状態にある金属
シリコンの溶湯を、上方に電子銃を配置した鋳型に注入
しつつ、該電子銃から出力した電子ビームで鋳型内の溶
湯面を走査、加熱しながら、該溶湯の下部から上部に向
けて一方向凝固させ、多結晶シリコンの鋳塊を製造する
に当たり、前記溶湯面を複数領域に区分けし、各領域に
投入されるエネルギー量が異なるように、各領域への電
子ビーム照射量を調整して、前記溶湯を凝固することを
特徴とする多結晶シリコン鋳塊の製造方法である。That is, according to the present invention, a molten metal silicon in a molten state is injected into a mold in which an electron gun is disposed above, and the surface of the molten metal in the mold is scanned and heated by an electron beam output from the electron gun. Meanwhile, the molten metal is unidirectionally solidified from a lower portion to an upper portion, and in producing an ingot of polycrystalline silicon, the molten metal surface is divided into a plurality of regions, and the amount of energy input to each region is different. A method for producing a polycrystalline silicon ingot, characterized in that the molten metal is solidified by adjusting the amount of electron beam irradiation to each region.
【００１０】また、本発明は、前記電子ビーム照射量の
調整を、電子銃の出力及び電子ビームの照射時間から選
ばれた１種以上を変更して行うことを特徴とする多結晶
シリコン鋳塊の製造方法である。さらに、本発明は、前
記領域の数を２〜４としたり、あるいは前記領域が受け
るエネルギー量の最大と最小の比を１．１以上とするこ
とを特徴とする多結晶シリコン鋳塊の製造方法である。Further, the present invention is characterized in that the adjustment of the amount of irradiation of the electron beam is performed by changing at least one selected from the output of the electron gun and the irradiation time of the electron beam. It is a manufacturing method of. Further, the present invention provides a method for producing a polycrystalline silicon ingot, wherein the number of the regions is set to 2 to 4, or the ratio of the maximum amount to the minimum amount of energy received by the regions is set to 1.1 or more. It is.
【００１１】加えて、本発明は、前記鋳塊を、鋳型底部
から連続的に引き抜き製造することを特徴とする多結晶
シリコンの製造方法でもある。本発明では、金属シリコ
ンを脱燐、脱ボロン、脱炭及び脱酸して得た溶融シリコ
ンを鋳造して一方向凝固で、該溶融シリコンが含有する
金属不純物元素を除去するに際し、溶湯面を複数領域に
区分けし、各領域に投入するエネルギー量に差をつける
ようにしたので、エネルギー投入量の大きい領域側の溶
湯面は電子衝突位置の変更で波立つと共に、各領域間に
は温度勾配が生じ、高温側領域から低温側領域に向けて
溶湯の流動が発生し、溶湯が撹拌されるようになる。そ
の結果、前記溶湯側の拡散層厚みδが、従来より格段と
小さくなり、金属不純物元素の実効分配係数が平衡分配
係数に近ずき、凝固した部分のうち該不純物元素の低い
部分が広がった鋳塊が得られる。その結果、従来よりシ
リコン歩留が向上し、電力原単位は低くなり、精製コス
トの低減が達成されて従来に比べ安価な太陽電池用シリ
コンが製造できるようになる。[0011] In addition, the present invention is also a method for producing polycrystalline silicon, wherein the ingot is continuously drawn from the bottom of the mold to produce the ingot. In the present invention, the molten silicon obtained by dephosphorizing, deboroning, decarburizing and deoxidizing metallic silicon is cast and unidirectionally solidified to remove metal impurity elements contained in the molten silicon. Since the area is divided into a plurality of areas and the amount of energy input to each area is made different, the molten metal surface on the side of the area where the energy input is large is wavy due to the change of the electron collision position, and the temperature gradient between each area Is generated, and the flow of the molten metal is generated from the high temperature side region toward the low temperature side region, so that the molten metal is stirred. As a result, the thickness δ of the diffusion layer on the molten metal side is much smaller than before, the effective distribution coefficient of the metal impurity element approaches the equilibrium distribution coefficient, and a portion of the solidified portion where the impurity element is low is widened. An ingot is obtained. As a result, the yield of silicon is improved, the power consumption is reduced, the cost of refining is reduced, and silicon for solar cells can be manufactured at a lower cost than before.
【００１２】[0012]
【発明の実施の形態】以下、発明をなすに至った経緯も
含めて、本発明の実施の形態を説明する。まず、発明者
は、従来の電子ビーム走査を実施した際の前記液相側の
拡散距離δを、不純物元素Ｆｅの初期濃度が７５０ｐｐ
ｍの溶湯を、凝固速度０．８ｍｍで、高さ３００ｍｍの
鋳塊を製造した場合で求めた。DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below, including the circumstances leading to the invention. First, the inventor sets the diffusion distance δ on the liquid phase side when the conventional electron beam scanning is performed to the initial concentration of the impurity element Fe of 750 pp.
m was obtained when a 300 mm high ingot was produced at a solidification rate of 0.8 mm.
【００１３】すなわち、鋳塊高さが底部より２６％の位
置でのＦｅ濃度は、０．４７ｐｐｍ，４７％の位置では
０．７８ｐｐｍであったので、それぞれの場合の実効分
配係数ｋは、ｋ＝ＣS ／ＣO より、６．２×１０-4及び
１．０×１０-3となる。Ｆｅの拡散係数Ｄは２×１０-4
ｃｍ2 ／ｓｅｃであるから、（１）式より前記δは４ｍ
ｍとなる。That is, since the Fe concentration at the position where the ingot height is 26% from the bottom is 0.47 ppm and the Fe concentration at the position where the ingot height is 47% is 0.78 ppm, the effective distribution coefficient k in each case is k = C S / C O , resulting in 6.2 × 10 -4 and 1.0 × 10 -3 . The diffusion coefficient D of Fe is 2 × 10 -4
cm 2 / sec, the above-mentioned δ is 4 m from the equation (1).
m.
【００１４】そこで、発明者は、このδを１桁以上小さ
くできれば、凝固精製の効率が大幅に向上すると考え、
電子ビームの走査方法を種々変更して、溶湯の撹拌を強
化することを試みた。つまり、電子ビームが湯面を打つ
とそこには凹凸が形成されること、及びエネルギー投入
量を溶湯面の位置によって差をつけると、温度勾配が生
じ、これら現象を上手に利用すれば湯の撹拌や流動が生
じ、該撹拌や流動によって前記拡散層の厚みが低減でき
ると考えたのである。なお、従来は、電子ビームの走査
を、単純な軌跡で走査時間を適当に定めて行っていたに
すぎない。Therefore, the present inventor believes that if this δ can be reduced by one digit or more, the efficiency of coagulation purification will be greatly improved.
We attempted to enhance the stirring of the molten metal by changing the scanning method of the electron beam in various ways. In other words, when the electron beam hits the molten metal surface, irregularities are formed there, and when the amount of energy input is made different depending on the position of the molten metal surface, a temperature gradient occurs. It was considered that agitation and flow occurred, and the thickness of the diffusion layer could be reduced by the agitation and flow. Conventionally, the scanning of the electron beam is merely performed by appropriately setting the scanning time on a simple trajectory.
【００１５】まず、発明者は、溶湯３面を複数領域に区
分けするようにした。区分けは、例えば、図９（ａ）及
び（ｂ）に示すが、溶湯３面を幾何学的中心線１０で分
離される４つの領域，あるいは幾何学的中心点１０から
鋳型壁までの距離の１／２の点を結んだ内側と外側の２
領域となるようにすれば良い。本発明では、これら領域
の数を限定するものではないが、あまり多くしても温度
勾配をつけること等で効果が変わらなくなるので、２〜
４程度が適切である。また、領域の輪郭もいかなる形状
にしても良いが、あまり複雑にしても実効に差がないの
で、円形、長方形等で十分である。First, the inventor has divided the three surfaces of the molten metal into a plurality of regions. The division is shown in FIGS. 9A and 9B, for example. As shown in FIG. Inner and outer 2 connecting 1/2 point
What is necessary is just to make it an area. In the present invention, the number of these regions is not limited. However, even if the number is too large, the effect is not changed by providing a temperature gradient or the like.
About 4 is appropriate. The contour of the region may be of any shape, but if it is too complicated, there is no difference in the effect, so that a circular or rectangular shape is sufficient.
【００１６】次に、各領域へ投入するエネルギーは、
（電子銃の出力×照射時間）で決める。例えば、各領域
への電子ビーム２の照射量は、出力一定とすれば照射時
間のみで変更でき操業が単純化できる。投入エネルギー
量の変更を、各領域の照射時間を一定にして、出力を経
時に変更したり、あるいは照射時間及び出力を共に変更
させても良いが、その場合は、操業が煩雑になる。勿
論、電子銃１１を複数使用してそれぞれの出力を異なら
せることも考えられる。例として、２つの領域で、一方
の投入エネルギー量を１とし、その変化を図１０に示
す。本発明は、図１０のように、各領域に投入するエネ
ルギー量の比を経時的に変化させて、領域間の溶湯３の
温度に差を生じさせるものである。Next, the energy input to each area is:
(Electron gun output x irradiation time) For example, the irradiation amount of the electron beam 2 to each area can be changed only by the irradiation time if the output is constant, and the operation can be simplified. The input energy amount may be changed by changing the irradiation time of each region to a constant value and changing the output over time, or changing both the irradiation time and the output. However, in that case, the operation becomes complicated. Of course, it is also conceivable to use a plurality of electron guns 11 to make their outputs different. As an example, in two regions, the input energy amount of one is set to 1, and the change is shown in FIG. In the present invention, as shown in FIG. 10, the ratio of the amount of energy input to each region is changed over time to cause a difference in the temperature of the molten metal 3 between the regions.
【００１７】なお、本発明では、各領域が受けるエネル
ギー量の最大と最小の比を１．１以上とすることが好ま
しい。１．１未満では、溶湯３の流動が前記拡散層厚み
δを所望の０．５ｍｍ以下にさせることが難しいからで
ある。また、電子ビーム２は各領域内の湯面上で走査さ
せるが、それが描く軌跡を、本発明では、円形状をＡ軌
跡，うず巻き状をＢ軌跡、矩形状をＣ軌跡，楕円状をＤ
軌跡と呼び、さらにＡ〜Ｄ軌跡において、各軌跡９間の
距離をｉ（＝１〜ｎ）段階に分け、その距離に応じて，
例えばＡ1 〜Ａi のような複数の軌跡を定めた。そし
て、これらのＡi 軌跡，Ｂi 軌跡，Ｃi 軌跡及びＤi 軌
跡を、例えば図２〜４に示すように、種々に組み合わせ
ることで、電子ビーム２の照射を規則的に行うようにし
ている。In the present invention, the ratio between the maximum and minimum amounts of energy received by each region is preferably set to 1.1 or more. If it is less than 1.1, it is difficult for the flow of the molten metal 3 to make the thickness δ of the diffusion layer equal to or less than the desired 0.5 mm. The electron beam 2 is scanned on the surface of the molten metal in each area. In the present invention, the trajectory drawn by the electron beam 2 is a circular A trajectory, a spiral trajectory B, a rectangular C trajectory, and an elliptical D trajectory.
The distance between the trajectories 9 in the trajectories A to D is divided into i (= 1 to n) stages, and according to the distances,
For example, a plurality of trajectories such as A 1 to A i are determined. Then, these A i locus, B i locus, the C i trajectories and D i the trajectory, for example, as shown in FIGS. 2-4, by combining a variety, the irradiation of the electron beam 2 so as to perform regularly I have.
【００１８】さらに、溶湯３の鋳造は、通常使用されて
いる水冷銅、あるいは黒鉛からなる鋳型１で、注入した
溶湯３をすべて凝固させてから鋳塊４を抜き出す所謂バ
ッチ式の鋳造方法でも使用できるが、本発明では、図１
に示すように、溶湯３を連続注入し、底部から鋳塊４を
引き抜く所謂連続鋳造方式の鋳造方法でも問題なく使用
できる。Further, the casting of the molten metal 3 is also used in a so-called batch type casting method in which a normally used mold 1 made of water-cooled copper or graphite is used to solidify all of the molten metal 3 and then withdraw an ingot 4. In the present invention, FIG.
As shown in FIG. 5, a so-called continuous casting method in which the molten metal 3 is continuously poured and the ingot 4 is pulled out from the bottom can be used without any problem.
【００１９】[0019]
【実施例】図７に示した太陽電池用シリコンの製造の真
空精製工程で、出発原料の金属シリコンを脱Ｐさせ、溶
融状態にあるシリコンを、図１に示したと同じ連続引抜
型の鋳型１に注入し、凝固精製させて長さ５０ｃｍの鋳
塊４を得る操業を行った。鋳型断面積は、７１０ｃｍ
2 ，溶湯３の注入量は９ｋｇ／ｈｒで凝固速度を０．９
ｍｍ／ｍｉｎとした。その際、溶湯３面の電子ビーム２
の走査を、本発明に係る方法と従来通りの方法とに従
い、以下のように行った。 （実施例１）電子銃の出力を１２０ｋＷ一定とし、溶湯
面を領域１、２に分け、各領域への電子ビームの照射時
間の比が１．１となるように、Ａ3 軌跡で電子ビームを
走査した。 （実施例２）溶湯面を領域１、２に分け、各領域にそれ
ぞれ電子銃を配置した。そして、照射時間は、両領域と
も等しくしたが、電子銃の出力を領域１が４０ｋＷ，領
域２が６０ｋＷで、且つ共にＢ2 軌跡になるよう電子ビ
ームを走査した。 （実施例３）溶湯面を同心円状に３分割し、投入エネル
ギー量が中心部領域と外周領域が多く、中間領域が低く
なるように、各領域ともＤ4 軌跡で電子ビームを走査し
た。走査は、出力１２０ｋＷの電子銃１本で行ったの
で、各領域に対する照射時間に差を付けた。 （従来例１）溶湯面を分割せず、出力１２０ｋＷの電子
銃で、Ａ3 軌跡になるよう電子ビームを照射した。DESCRIPTION OF THE PREFERRED EMBODIMENTS In a vacuum refining step of manufacturing silicon for a solar cell shown in FIG. 7, metallic silicon as a starting material is removed and silicon in a molten state is converted into a continuous drawing mold 1 as shown in FIG. , And solidified and refined to obtain an ingot 4 having a length of 50 cm. Mold cross section is 710cm
2. The injection amount of the molten metal 3 is 9 kg / hr and the solidification rate is 0.9.
mm / min. At this time, the electron beam 2
Was performed as follows according to the method of the present invention and the conventional method. (Example 1) the output of the electron gun and 120kW constant, divided molten surface area 1,2, such that the ratio of the irradiation time of the electron beam to each region is 1.1, the electron beam at A 3 locus Was scanned. (Example 2) The melt surface was divided into regions 1 and 2, and an electron gun was arranged in each region. The irradiation time was equal in both regions, the output of the electron gun region 1 40 kW, region 2 at 60 kW, and is scanned with an electron beam so that both of the B 2 locus. (Example 3) the molten metal surface was divided into three concentric, amount input energy is often the central area and the peripheral region, so that the intermediate region becomes lower, and scanning the electron beam in the D 4 trajectory in each region. Since the scanning was performed with one electron gun having an output of 120 kW, the irradiation time for each region was made different. Without dividing the (conventional example 1) molten metal surface, an electron gun output 120 kW, were irradiated with an electron beam so that the A 3 locus.
【００２０】これらの評価は、不純物濃化部を切断除去
した鋳塊４の長さ（高さ）で行われるが、該不純物濃化
部の切断位置は、以下のようにして決定した。例えば、
鋳塊４の高さ方向におけるＦｅ濃度の分布を、図８に従
来方法で凝固させたものとの比較で示す。図８におい
て、本発明に係る製造方法で得た鋳塊４は、Ｆｅの濃度
から点線で示す高さで太陽電池用シリコンとして使用で
きることになる。従って、その位置で切断すると、従来
法で得た鋳塊４より、長さで１６％に相当する分だけ、
シリコン歩留が向上するのである。These evaluations are performed on the length (height) of the ingot 4 from which the impurity-concentrated portion has been cut and removed. The cutting position of the impurity-concentrated portion was determined as follows. For example,
The distribution of the Fe concentration in the height direction of the ingot 4 is shown in FIG. 8 in comparison with the ingot 4 solidified by the conventional method. In FIG. 8, the ingot 4 obtained by the manufacturing method according to the present invention can be used as silicon for solar cells at the height indicated by the dotted line from the concentration of Fe. Therefore, when cutting at that position, the ingot 4 obtained by the conventional method has a length equivalent to 16%,
The silicon yield is improved.
【００２１】上記実施例１〜３及び比較例１の操業結果
を、一括して表１に示す。表１では切断除去後の鋳塊
が、従来法よりも本発明法の適用時に高く、また電力原
単位が小さくなっている。つまり、本発明の優れている
ことが確認できた。The operation results of Examples 1 to 3 and Comparative Example 1 are collectively shown in Table 1. In Table 1, the ingot after cutting and removal is higher when the method of the present invention is applied and the power consumption is smaller than that of the conventional method. That is, it was confirmed that the present invention was excellent.
【００２２】[0022]
【表１】 [Table 1]
【００２３】そこで、本発明を適用して得た鋳塊４を、
その後流の酸化精錬及び仕上凝固精製工程を経て、太陽
電池用シリコンとした。その基板で製作した太陽電池の
光電変換効率を測定したところ、その値は、１２〜１４
％と良好な結果であった。Therefore, the ingot 4 obtained by applying the present invention is
After that, it was subjected to oxidative refining and finish coagulation refining steps, to obtain silicon for solar cells. When the photoelectric conversion efficiency of the solar cell manufactured on the substrate was measured, the value was 12 to 14.
%, Which is a good result.
【００２４】[0024]
【発明の効果】以上述べたように、本発明により、太陽
電池用シリコンの製造工程において、多結晶シリコンの
鋳塊が、従来より効率良く行えるようになる。その結
果、金属不純物元素の除去が安定して行えるようになる
と共に、シリコン歩留の向上、精製コストの低減が達成
され、安価な太陽電池用シリコン基板が製造できるよう
になった。As described above, according to the present invention, ingots of polycrystalline silicon can be formed more efficiently in the manufacturing process of silicon for solar cells than in the past. As a result, metal impurity elements can be stably removed, silicon yield can be improved, purification cost can be reduced, and inexpensive silicon substrates for solar cells can be manufactured.
【図１】本発明に係る多結晶シリコン鋳塊の製造方法を
実施する鋳型例を示す縦断面図である。FIG. 1 is a longitudinal sectional view showing an example of a mold for carrying out a method for producing a polycrystalline silicon ingot according to the present invention.
【図２】本発明に係る多結晶シリコン鋳塊の製造方法を
実施する際の電子ビームの軌跡例（鋳型断面が円形）を
示す図である。FIG. 2 is a diagram showing an example of an electron beam trajectory (a mold having a circular cross section) when the method of manufacturing a polycrystalline silicon ingot according to the present invention is performed.
【図３】本発明に係る多結晶シリコン鋳塊の製造方法を
実施する際の電子ビームの別の軌跡例（鋳型断面が長方
形）を示す図である。FIG. 3 is a diagram showing another example of a trajectory of an electron beam (a mold having a rectangular cross section) when the method of manufacturing a polycrystalline silicon ingot according to the present invention is performed.
【図４】本発明に係る多結晶シリコン鋳塊の製造方法を
実施する際の電子ビームの別の軌跡例（鋳型断面が正方
形）を示す図である。FIG. 4 is a diagram showing another example of a trajectory of an electron beam (a mold having a square cross section) when the method of manufacturing a polycrystalline silicon ingot according to the present invention is performed.
【図５】溶融シリコンの凝固精製の原理を説明する図で
ある。FIG. 5 is a diagram illustrating the principle of solidification purification of molten silicon.
【図６】従来の太陽電池用シリコンを工業生産するプロ
セスを示す流れ図である。FIG. 6 is a flowchart showing a conventional process for industrially producing silicon for a solar cell.
【図７】本出願人が提案した太陽電池用シリコンを工業
生産するプロセスを示す流れ図である。FIG. 7 is a flowchart showing a process of industrially producing silicon for a solar cell proposed by the present applicant.
【図８】本発明法と従来法とで製造した鋳塊中Ｆｅ濃度
の高さ方向の分布を示す図である。FIG. 8 is a view showing the distribution of the Fe concentration in the ingot in the height direction in the ingots manufactured by the method of the present invention and the conventional method.
【図９】溶湯面の区分け方法を説明する図であり、
（ａ）は４分割、（ｂ）は同心円状に２分割した領域を
示す。FIG. 9 is a view for explaining a method of dividing a molten metal surface,
(A) shows an area divided into four parts, and (b) shows an area divided into two parts concentrically.
【図１０】２分割した領域でのエネルギー量の差を示す
図である。 １ 鋳型 ２ 電子ビーム ３ 溶融シリコン（溶湯） ４ 鋳塊 ５ 鋳塊引抜き方向 ６ 凝固界面 ７ 溶湯の流動を示す矢印 ８ 湯面 ９ 軌跡 １０ 幾何学的中心線 １１ 電子銃FIG. 10 is a diagram showing a difference in energy amount between two divided areas. REFERENCE SIGNS LIST 1 mold 2 electron beam 3 molten silicon (molten metal) 4 ingot 5 ingot withdrawal direction 6 solidification interface 7 arrow indicating flow of molten metal 8 molten metal surface 9 trajectory 10 geometric center line 11 electron gun
───────────────────────────────────────────────────── フロントページの続き (72)発明者 阿部 正道 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 花澤 和浩 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 馬場 裕幸 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 阪口 泰彦 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 渡壁 史朗 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masamichi Abe 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. Kawasaki Steel Engineering Co., Ltd. (72) Kazuhiro Hanazawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Inside the Technical Research Institute of Iron and Steel Corporation (72) Inventor Hiroyuki Baba 1st Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Center of Kawasaki Steel Corporation (72) Yasuhiko Sakaguchi 1st Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki (72) Inventor Shiro Watanabe 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref.
Claims (5)
上方に電子銃を配置した鋳型に注入しつつ、該電子銃か
ら出力した電子ビームで鋳型内の溶湯面を走査、加熱し
ながら、該溶湯の下部から上部に向けて一方向凝固さ
せ、多結晶シリコンの鋳塊を製造するに当たり、 前記溶湯面を複数領域に区分けし、各領域に投入される
エネルギー量が異なるように、各領域への電子ビーム照
射量を調整して、前記溶湯を凝固することを特徴とする
多結晶シリコン鋳塊の製造方法。1. A molten metal silicon in a molten state,
While injecting into the mold with the electron gun arranged above, the surface of the molten metal in the mold is scanned and heated by the electron beam output from the electron gun, and is solidified in one direction from the lower part to the upper part of the molten metal while being polycrystalline. In producing an ingot of silicon, the melt surface is divided into a plurality of regions, and the amount of electron beam applied to each region is adjusted so that the amount of energy applied to each region is different, and the melt is solidified. A method for producing a polycrystalline silicon ingot, characterized in that:
の出力及び電子ビームの照射時間から選ばれた１種以上
を変更して行うことを特徴とする請求項１記載の多結晶
シリコン鋳塊の製造方法。2. The polycrystalline silicon casting according to claim 1, wherein the adjustment of the electron beam irradiation amount is performed by changing at least one selected from an output of an electron gun and an irradiation time of the electron beam. How to make a lump.
とする請求項１又は２記載の多結晶シリコン鋳塊の製造
方法。3. The method according to claim 1, wherein the number of the regions is 2 to 4.
最小の比を１．１以上とすることを特徴とする請求項１
〜３いずれか記載の多結晶シリコン鋳塊の製造方法。4. The method according to claim 1, wherein a ratio between a maximum and a minimum of an amount of energy received by the region is 1.1 or more.
4. The method for producing a polycrystalline silicon ingot according to any one of claims 3 to 3.
抜き製造することを特徴とする請求項１〜４いずれか記
載の多結晶シリコンの製造方法。5. The method for producing polycrystalline silicon according to claim 1, wherein the ingot is continuously drawn from the bottom of the mold.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9077974A JPH10273313A (en) | 1997-03-28 | 1997-03-28 | Production of polycrystal silicon ingot |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9077974A JPH10273313A (en) | 1997-03-28 | 1997-03-28 | Production of polycrystal silicon ingot |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10273313A true JPH10273313A (en) | 1998-10-13 |
Family
ID=13648881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9077974A Withdrawn JPH10273313A (en) | 1997-03-28 | 1997-03-28 | Production of polycrystal silicon ingot |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10273313A (en) |
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|---|---|---|---|---|
| JP2007095972A (en) * | 2005-09-28 | 2007-04-12 | Kyocera Corp | Solar cell silicon substrate and its manufacturing method |
| WO2008114822A1 (en) | 2007-03-19 | 2008-09-25 | Mnk-Sog Silicon, Inc. | Method and apparatus for manufacturing silicon ingot |
| WO2009008555A1 (en) * | 2007-07-12 | 2009-01-15 | Sumitomo Chemical Company, Limited | Method for production of purified silicon |
| JP2009102213A (en) * | 2007-07-12 | 2009-05-14 | Sumitomo Chemical Co Ltd | Manufacturing method of purified silicon |
| US7727502B2 (en) | 2007-09-13 | 2010-06-01 | Silicum Becancour Inc. | Process for the production of medium and high purity silicon from metallurgical grade silicon |
| JP2009114053A (en) * | 2007-10-17 | 2009-05-28 | Sumitomo Chemical Co Ltd | Method for producing purified silicon |
| US8404016B2 (en) | 2008-08-01 | 2013-03-26 | Ulvac, Inc. | Method for refining metal |
| US8409319B2 (en) | 2008-08-12 | 2013-04-02 | Ulvac, Inc. | Silicon purification method |
| CN102112394A (en) * | 2008-08-12 | 2011-06-29 | 株式会社爱发科 | Silicon purification method |
| WO2010018831A1 (en) * | 2008-08-12 | 2010-02-18 | 株式会社アルバック | Silicon purification method |
| JP5315345B2 (en) * | 2008-08-12 | 2013-10-16 | 株式会社アルバック | Silicon purification method |
| KR101309521B1 (en) * | 2010-11-29 | 2013-09-23 | 한국에너지기술연구원 | Apparatus for manufacturing polysilicon with high purity using electron-beam melting and method of manufacturing polysilicon using the same |
| CN102145893A (en) * | 2011-05-16 | 2011-08-10 | 大连隆田科技有限公司 | Method for purifying polysilicon by adopting electron beam to carry out fractionated smelting |
| CN103086379A (en) * | 2013-01-23 | 2013-05-08 | 大连理工大学 | Radiation-intercepting device of crucible for electron-beam smelting |
| CN108946739A (en) * | 2018-10-16 | 2018-12-07 | 青岛蓝光晶科新材料有限公司 | A kind of silicon materials process for effectively purifying and device |
| CN109110766A (en) * | 2018-10-16 | 2019-01-01 | 青岛蓝光晶科新材料有限公司 | The method and apparatus that silicon material efficiently purifies after a kind of medium melting |
| CN109133067A (en) * | 2018-10-16 | 2019-01-04 | 青岛蓝光晶科新材料有限公司 | A kind of method and device improving electron-beam smelting polysilicon efficiency |
| CN109133067B (en) * | 2018-10-16 | 2023-06-27 | 青岛蓝光晶科新材料有限公司 | Method and device for improving efficiency of electron beam smelting of polycrystalline silicon |
| CN109110766B (en) * | 2018-10-16 | 2023-09-01 | 青岛蓝光晶科新材料有限公司 | Method and device for efficiently purifying silicon material after medium smelting |
| CN108946739B (en) * | 2018-10-16 | 2023-09-19 | 青岛蓝光晶科新材料有限公司 | Efficient purification method and device for silicon material |
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