JP3408917B2 - High purity quartz glass and method for producing the same - Google Patents

High purity quartz glass and method for producing the same

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Publication number
JP3408917B2
JP3408917B2 JP06111896A JP6111896A JP3408917B2 JP 3408917 B2 JP3408917 B2 JP 3408917B2 JP 06111896 A JP06111896 A JP 06111896A JP 6111896 A JP6111896 A JP 6111896A JP 3408917 B2 JP3408917 B2 JP 3408917B2
Authority
JP
Japan
Prior art keywords
quartz glass
quartz
content
zirconium
raw material
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.)
Expired - Lifetime
Application number
JP06111896A
Other languages
Japanese (ja)
Other versions
JPH09255346A (en
Inventor
克彦 剣持
寛幸 宮澤
博行 渡辺
清貴 前川
忠左衛門 辻
学 斉藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shin Etsu Quartz Products Co Ltd
Original Assignee
Shin Etsu Quartz Products Co Ltd
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Filing date
Publication date
Application filed by Shin Etsu Quartz Products Co Ltd filed Critical Shin Etsu Quartz Products Co Ltd
Priority to JP06111896A priority Critical patent/JP3408917B2/en
Publication of JPH09255346A publication Critical patent/JPH09255346A/en
Application granted granted Critical
Publication of JP3408917B2 publication Critical patent/JP3408917B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2203/00—Production processes

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Glass Compositions (AREA)
  • Silicon Compounds (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、半導体工業や光通
信分野で用いられる石英ガラスおよびその製造方法に関
し、特にジルコニウム元素含有量が少ない石英ガラス、
例えばシリコン単結晶引上げ用石英ガラスルツボ及びそ
の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to quartz glass used in the semiconductor industry and optical communication fields and a method for producing the same, and in particular, quartz glass containing a small amount of zirconium element,
For example, the present invention relates to a quartz glass crucible for pulling a silicon single crystal and a method for manufacturing the same.

【０００２】[0002]

【関連技術】従来、天然石英を原料としてこれを溶融ガ
ラス化して石英ガラスを製造するにあたって、高純度の
石英ガラスを必要とする場合は、種々の単位精製手段を
経て純度を高めた原料を加熱溶融して製造していた。[Related Art] Conventionally, when high-purity quartz glass is required in the production of fused silica by using natural quartz as a raw material to melt and vitrify it, heating the raw material with increased purity through various unit purification means. It was manufactured by melting.

【０００３】単位精製手段としては、粉砕、分級、浮遊
選鉱、磁力選鉱、エッチング、高温加熱、ハロゲン含有
雰囲気熱処理、電気分解精製などが主なものである。The main unit refining means are crushing, classification, flotation, magnetic separation, etching, high temperature heating, heat treatment in a halogen-containing atmosphere, electrolysis refining and the like.

【０００４】[0004]

【発明が解決しようとする課題】しかし、こうして高純
度化した原料を用い、加熱溶融時の汚染を極力防止して
もなお除ききれない元素があった。そして、その幾つか
は半導体工業用や光学用に用いた場合にその性能を害す
る元素である。近年の半導体工学や光学技術の進歩は、
従来許容できていたレベルの含有量でも有害な量である
として許容しないところまで来ている。However, there are some elements that cannot be removed even if the contamination at the time of heating and melting is prevented as much as possible using the highly purified raw material. And, some of them are elements that impair their performance when used for the semiconductor industry or for optics. Recent advances in semiconductor engineering and optical technology
Even if the content was at a level that was acceptable in the past, it has reached the point where it is not acceptable because it is a harmful amount.

【０００５】特に、ジルコニウム元素は、天然石英ガラ
ス中では１ｐｐｍ程度は含まれるのが当然とされていた
が、更に低減すること、好ましくは０．８ｐｐｍ以下に
することが望まれている。なお、本明細書ではｐｐｍで
という濃度表示は重量濃度をあらわす重量ｐｐｍを意味
する。[0007] In particular, although it has been understood that the zirconium element is contained in natural quartz glass in an amount of about 1 ppm, it is desired to further reduce it, preferably to 0.8 ppm or less. In the present specification, the concentration indication in ppm means weight ppm indicating weight concentration.

【０００６】しかしながら、前述のような従来の精製技
術を駆使して、ジルコニウム元素含有量が０．２ｐｐｍ
以下と分析されるような高純度石英粉を製造しても、こ
れを溶融して得た石英ガラスは１ｐｐｍ程度のジルコニ
ウム元素を含んでしまうという不都合があった。However, by utilizing the conventional refining techniques as described above, the zirconium element content is 0.2 ppm.
Even if a high-purity silica powder as analyzed below is produced, the silica glass obtained by melting the silica powder has a disadvantage that it contains about 1 ppm of zirconium element.

【０００７】この様にして製造したジルコニウム元素含
有量が１ｐｐｍ程度の単結晶引き上げ用石英ガラスルツ
ボを用いると、ジルコニウム元素含有量が０．２ｐｐｍ
以下の合成石英ガラスのルツボを用いた時のような良質
のシリコン単結晶を得ることが出来なかった。When the quartz glass crucible for pulling a single crystal having a zirconium element content of about 1 ppm produced as described above is used, the zirconium element content is 0.2 ppm.
It was not possible to obtain a high-quality silicon single crystal as when using the following synthetic quartz glass crucible.

【０００８】本発明は、上記した事情に鑑みなされたも
ので、天然石英を原料として高純度、特にジルコニウム
（Ｚｒ）が少なくかつ安価に製造される高純度石英ガラ
ス及びその製造方法を提供することを目的とする。The present invention has been made in view of the above circumstances, and provides a high-purity quartz glass which is manufactured from natural quartz with a high purity, particularly, a low amount of zirconium (Zr) and at a low cost, and a method for producing the same. With the goal.

【０００９】[0009]

【課題を解決するための手段】上記目的を達成するため
に、本発明の高純度石英ガラスの製造方法は、結晶質天
然石英を加熱溶融して製造する天然石英ガラスの製造方
法において、該結晶質天然石英原料を一つ以上の単位精
製手段の組み合わせを順次実施して精製するにあたり、
所定の単位精製手段を実施後に当該石英原料の一部を分
析のために抜き取り、これをフッ化水素酸或いはフッ化
水素酸と他の無機酸との混酸で分解した後、その分解液
をそのままあるいは他の無機酸を更に添加した後に蒸発
乾固し、残留物にアルカリ金属の塩または水酸化物を加
えて加熱溶融し、その後このアルカリ金属の塩または水
酸化物を無機酸水溶液または純水で溶解して、該溶液中
の不純物を定量分析することによって、結晶質天然石英
中の不純物含有量を求め、この不純物含有量が所定の値
以下である精製結晶質天然石英を原料として加熱溶融に
よって高純度石英ガラスを製造することを特徴とする。In order to achieve the above object, a method for producing high-purity quartz glass according to the present invention is a method for producing natural quartz glass by heating and melting crystalline natural quartz. In purifying a natural quartz raw material by sequentially combining one or more unit purification means,
After carrying out a predetermined unit purification means, a part of the quartz raw material is extracted for analysis and decomposed with hydrofluoric acid or a mixed acid of hydrofluoric acid and other inorganic acid, and then the decomposed solution is left as it is. Alternatively, after further adding another inorganic acid, the mixture is evaporated to dryness, an alkali metal salt or hydroxide is added to the residue and the mixture is heated and melted, and then the alkali metal salt or hydroxide is added to an inorganic acid aqueous solution or pure water. Dissolved in the solution and quantitatively analyzing the impurities in the solution to determine the content of impurities in the crystalline natural quartz. The purified crystalline natural quartz whose content is below a specified value is melted by heating. It is characterized by producing high-purity quartz glass by.

【００１０】天然石英原料の精製手段としては次のよう
な方法が一般的にとられている。まず天然石英原料を粉
砕して粉体とし、洗浄や浮遊選鉱、磁力選鉱、フッ化水
素酸によるエッチングなどで高純度の石英粉とする。こ
れらの処理にあたっては、特開昭５２−１２１０１７号
公報記載の方法（浮遊選鉱）や特公昭３８−２１９８６
号公報記載の方法（酸洗浄）などを応用することが出来
る。The following method is generally used as a means for refining a raw material for natural quartz. First, a natural quartz raw material is pulverized into a powder, which is then washed or subjected to flotation, magnetic separation, etching with hydrofluoric acid or the like to obtain a high-purity quartz powder. In these treatments, the method described in JP-A-52-121017 (flotation) or JP-B-38-21986 is used.
The method described in Japanese Patent Publication (acid cleaning) can be applied.

【００１１】通常、このような方法で、数％のジルコニ
ウム元素を含んだ原石から、１〜２ｐｐｍ程度のジルコ
ニウム元素含有量の石英粉を得ることが出来る。なお、
石英粉は結晶学的には水晶粉と同じであり、本明細書で
は区別しない。In general, quartz powder having a zirconium element content of about 1 to 2 ppm can be obtained from a rough stone containing a few percent zirconium element by such a method. In addition,
Quartz powder is crystallographically the same as quartz powder and is not distinguished herein.

【００１２】次に、アルカリ元素、鉄元素あるいは銅元
素をさらに低減させるために、ハロゲン元素含有雰囲気
で１０００℃程度に加熱処理する。この処理は一般的な
不純物を除く手段として公知である（特開昭４８−６９
７９４号公報）。この処理によって、アルカリ元素が
０．２ｐｐｍ以下、銅元素が０．１ｐｐｍ以下の精製原
料が得られる。このとき、通常の石英ガラスの分析方法
で評価すると、同時にジルコニウム元素も０．２ｐｐｍ
以下に精製されているように見える。Next, in order to further reduce the alkali element, the iron element or the copper element, heat treatment is performed at about 1000 ° C. in a halogen element-containing atmosphere. This treatment is known as a general means for removing impurities (JP-A-48-69).
794). By this treatment, a refined raw material having an alkali element of 0.2 ppm or less and a copper element of 0.1 ppm or less can be obtained. At this time, when evaluated by an ordinary quartz glass analysis method, zirconium element is also 0.2 ppm at the same time.
It appears to have been purified below.

【００１３】通常の石英ガラスの分析方法としては、フ
ッ化水素酸を用いて分解溶液化し、この溶液をそのまま
フレームレス原子吸光光度計で分析したり、蒸発乾固後
希硝酸で回収して、ＩＣＰ−ＡＥＳ（プラズマ発光法）
やＩＣＰ−ＭＳ（プラズマ質量分析）で分析したりする
方法がある。また、特開平７−７２０５６号公報に開示
されたような、フッ化水素ガスで分解と蒸発乾固を同時
に行うような改良方法も用いられはじめている。As a usual method for analyzing quartz glass, hydrofluoric acid is used to decompose and make a solution, and this solution is directly analyzed by a flameless atomic absorption spectrophotometer, or evaporated to dryness, and then recovered with dilute nitric acid. ICP-AES (plasma emission method)
And ICP-MS (plasma mass spectrometry). Further, an improved method such as that disclosed in Japanese Patent Laid-Open No. 7-72056, in which decomposition and evaporation to dryness are simultaneously performed with hydrogen fluoride gas, has also begun to be used.

【００１４】しかし、本発明の方法で用いる分析方法で
は蒸発乾固後に残留物を溶融アルカリ化合物で回収す
る。このアルカリ化合物をさらに水溶液化し、この溶液
を通常の分離・分析手段で定量的に分析するものであ
る。However, in the analytical method used in the method of the present invention, the residue is recovered with a molten alkali compound after evaporation to dryness. This alkaline compound is further made into an aqueous solution, and this solution is quantitatively analyzed by a usual separation / analysis means.

【００１５】このようにすると、従来の分析方法では
０．２ｐｐｍ以下に精製されたように見えた石英粉から
も１ｐｐｍ程度のジルコニウム元素が分析されることが
あることがわかった。In this way, it was found that in the conventional analysis method, about 1 ppm of zirconium element may be analyzed even from the quartz powder which appeared to be purified to 0.2 ppm or less.

【００１６】中性子放射化分析のような方法によれば存
在形態にかかわらず全量のジルコニウム元素が分析でき
る。通常のフッ化水素酸で分解してＩＣＰ−ＡＥＳ（プ
ラズマ発光法）等で分解溶液を分析する分析方法では十
分純化されたように見えてもなお、純化を繰り返した
り、純化されやすい出発原料の場合は、ジルコニウム元
素含有量が０．８ｐｐｍ以下、さらには０．３ｐｐｍ程
度にまで純化されるのがわかる。According to a method such as neutron activation analysis, the total amount of zirconium element can be analyzed regardless of the existing form. Although it seems to be sufficiently purified by the analysis method of decomposing it with ordinary hydrofluoric acid and analyzing the decomposing solution by ICP-AES (plasma emission method), etc. In this case, it can be seen that the zirconium element content is purified to 0.8 ppm or less, further to about 0.3 ppm.

【００１７】従来の分析方法では原料石英粉のジルコニ
ウム元素含有量と製造された石英ガラス中のジルコニウ
ム元素含有量の分析値は関連が無い様にしかみえなかっ
た。本発明の分析方法を採用するとはじめて、原料石英
粉中のジルコニウム含有量と得られた石英ガラス中のジ
ルコニウム含有量の分析報告値を一致させることが出来
た。According to the conventional analysis method, it seems that the zirconium element content of the raw material quartz powder and the analysis value of the zirconium element content in the produced quartz glass have no relation to each other. Only when the analysis method of the present invention was adopted, the zirconium content in the raw material quartz powder and the zirconium content in the obtained silica glass could be reported to be the same.

【００１８】例えば、従来の方法で分析・選別を行なう
場合、０．８ｐｐｍ以下のジルコニウム含有量の石英ガ
ラスを製造するために、０．８ｐｐｍジルコニウム含有
量以下の石英粉を選別利用して石英ガラスを製造して
も、０．８ｐｐｍを越える不合格品が出来てしまうこと
が３０％ほどあった。For example, in the case where analysis and selection are carried out by the conventional method, in order to produce a quartz glass having a zirconium content of 0.8 ppm or less, quartz glass having a zirconium content of 0.8 ppm or less is selectively used. Even if it was produced, about 30% of the cases produced a rejected product exceeding 0.8 ppm.

【００１９】これに対し、本発明の方法で分析・選別を
行うと不合格は全くでなくなった。石英ガラスのジルコ
ニウム含有量は原料中のジルコニウム含有量に等しいよ
うに溶融工程での汚染を管理する事も可能になった。On the other hand, when analysis and selection were carried out by the method of the present invention, no rejection was found. It has also become possible to control contamination in the melting process so that the zirconium content of the quartz glass is equal to the zirconium content of the raw material.

【００２０】本発明者等は、特にジルコニウム（Ｚｒ）
元素含有量の少ない石英ガラスルツボを得るために鋭意
研究した結果、次の知見を得るにいたった。浮遊選鉱や
フッ化水素酸での洗浄でジルコニウム（Ｚｒ）を減少さ
せることはできるが１〜２ｐｐｍ程度までが実質的な限
界である。このものとこれを溶融した石英ガラスを、従
来の方法で分析した場合、原料石英粉のジルコニウム
（Ｚｒ）含有量と、石英ガラス中のジルコニウム（Ｚ
ｒ）含有量は一致する。The present inventors have found that, in particular, zirconium (Zr)
As a result of earnest research to obtain a quartz glass crucible having a small element content, the following findings have been obtained. Zirconium (Zr) can be reduced by flotation or washing with hydrofluoric acid, but the practical limit is about 1 to 2 ppm. When this substance and fused silica glass were analyzed by a conventional method, the zirconium (Zr) content of the raw quartz powder and the zirconium (Zr
r) Content is consistent.

【００２１】ハロゲン元素を含む雰囲気で加熱処理する
とジルコニウム（Ｚｒ）元素含有量をさらに低減するこ
とが出来る。真の総含有量を低減できるが、従来方法で
分析すると、実際以上に急速に純化されたように見えて
しまう。すなわち、１回のハロゲン雰囲気中加熱で原料
水晶粉中のジルコニウム（Ｚｒ）は０．２ｐｐｍ以下に
分析されるが、これを溶融して得た石英ガラス中のジル
コニウム（Ｚｒ）含有量は１．０ｐｐｍと分析されるよ
うなことがしばしば起こる。The heat treatment in an atmosphere containing a halogen element can further reduce the zirconium (Zr) element content. Although the true total content can be reduced, analysis by conventional methods appears to purify more rapidly than it actually is. That is, zirconium (Zr) in the raw material crystal powder is analyzed to 0.2 ppm or less by heating once in a halogen atmosphere, but the zirconium (Zr) content in the quartz glass obtained by melting the powder is 1. It often happens that it is analyzed as 0 ppm.

【００２２】ハロゲン元素を含む雰囲気で加熱処理した
場合は、従来の分析方法では実際に石英粉に含有されて
いるジルコニウム（Ｚｒ）の総量を知ることが出来な
い。本発明の、溶融アルカリ化合物を用いた分析方法で
のみ実際に石英粉に含有されているジルコニウム（Ｚ
ｒ）の総量を知ることが出来る。他方、溶融ガラス化し
た石英ガラス中のジルコニウム（Ｚｒ）含有量は、従来
の分析方法でも、本発明の方法で採用している分析方法
でも正しく知ることが出来る。When the heat treatment is performed in an atmosphere containing a halogen element, the total amount of zirconium (Zr) contained in the quartz powder cannot be actually known by the conventional analysis method. Zirconium (Z that is actually contained in the quartz powder only by the analysis method of the present invention using the molten alkali compound is
The total amount of r) can be known. On the other hand, the zirconium (Zr) content in the fused vitrified quartz glass can be correctly known by the conventional analysis method or the analysis method employed in the method of the present invention.

【００２３】ジルコニウム（Ｚｒ）元素がハロゲン雰囲
気中加熱で低減されてゆく速度は、原料の履歴や由来に
よるものなのか、一定でない。ハロゲン雰囲気中加熱後
のジルコニウム（Ｚｒ）含有量を分析して把握し選別す
ることでのみ、安定して低ジルコニウム（Ｚｒ）含有量
の石英粉原料を用いることが出来、結果として歩留り良
く、低ジルコニウム（Ｚｒ）含有量の石英ガラスを製造
することが出来る。The rate at which the zirconium (Zr) element is reduced by heating in a halogen atmosphere is not constant, depending on the history and origin of the raw material. Only by analyzing and grasping and selecting the zirconium (Zr) content after heating in a halogen atmosphere, a quartz powder raw material having a low zirconium (Zr) content can be stably used, resulting in a good yield and a low yield. Quartz glass having a zirconium (Zr) content can be manufactured.

【００２４】本発明者等の研究によれば、本発明で採用
しているジルコニウム元素の分析方法と同様に含有ジル
コニウムの総量を知る他の手段は中性子放射化分析であ
る。この方法は中性子源として大型設備を必要とするな
どのために高価な方法であり、そのため世界で利用でき
る設備も少ないので迅速な分析もできない。製造ライン
に組み込んで品質をモニタする分析方法としては採用し
難いものである。According to the research conducted by the present inventors, another means for knowing the total amount of zirconium contained is the neutron activation analysis as in the method for analyzing elemental zirconium employed in the present invention. This method is expensive because it requires a large-scale facility as a neutron source, and therefore, there are few facilities available in the world, so rapid analysis cannot be performed. It is difficult to use as an analysis method for monitoring the quality by incorporating it into the production line.

【００２５】本発明の方法で採用する分析方法を詳述す
ると、以下のようである。まず、水晶粉をフッ化水素酸
と共に加圧酸分解容器中で１００℃以上に加熱して分解
溶液化する。このフッ化水素酸の代わりにフッ化水素酸
と他の無機酸との混酸を用いることもできる。ここでい
う他の無機酸としては、硝酸や硫酸をあげることができ
る。The analytical method used in the method of the present invention is described in detail below. First, crystal powder is heated with hydrofluoric acid in a pressurized acid decomposition container to 100 ° C. or higher to form a decomposition solution. Instead of this hydrofluoric acid, a mixed acid of hydrofluoric acid and another inorganic acid can be used. Examples of the other inorganic acid mentioned here include nitric acid and sulfuric acid.

【００２６】次に、このフッ化けい素酸を主成分とする
溶液を開放状態で加熱すると、揮発性のフッ化けい素酸
は揮発散逸してしまい、けい素成分が無くなって不純物
を含む残留物だけが残る。分析化学では「乾固」という
操作は必ずしも「固体にする」事を意味しない。固体に
なるまで乾かしてしまうと後の工程で希薄な酸では回収
できなくなる場合もある。Next, when the solution containing silicon fluoride as a main component is heated in an open state, the volatile silicon fluoride is volatilized and dissipated, and the silicon component is lost and the residual impurities are contained. Only things remain. In analytical chemistry, the operation "drying" does not necessarily mean "solidifying". If it is dried until it becomes a solid, it may not be possible to recover it with a dilute acid in a later step.

【００２７】この蒸発乾固処理は、揮発性の物質が完全
に揮発散逸することが目的であるから、不揮発性の酸と
して、少量の硫酸を加えてから硫酸白煙が出るまで加熱
する操作も「乾固」と呼んでいる。特に区別して「白煙
乾固」と呼ぶ事もある。本発明の場合では、硫酸を加え
て白煙乾固すると主成分のけい素やフッ素を完全に取り
除くことができる。白煙乾固に際して加える酸として
は、硫酸ばかりでなく硝酸や過塩素酸を用いることもあ
る。The purpose of this evaporation-drying treatment is to volatilize and dissipate the volatile substances completely, and therefore, a small amount of sulfuric acid is added as a non-volatile acid, and then heating operation is performed until sulfuric acid white smoke appears. We call it "dryness". In particular, it is sometimes called “white smoke dryness”. In the case of the present invention, the main components such as silicon and fluorine can be completely removed by adding sulfuric acid to dryness in white smoke. As the acid to be added when the white smoke is dried, not only sulfuric acid but also nitric acid or perchloric acid may be used.

【００２８】本発明では、この蒸発乾固の次に残留物を
アルカリ溶融する。アルカリ溶融という操作は、水溶液
ではないアルカリ金属の塩等の化合物を加熱溶融して、
数百℃以上の溶解力の強い液体とし、これに目的物質を
溶解する操作である。In the present invention, after evaporation to dryness, the residue is alkali-melted. The operation of alkali melting is performed by heating and melting a compound such as an alkali metal salt that is not an aqueous solution,
This is an operation of dissolving a target substance in a liquid having a strong dissolving power of several hundreds of degrees Celsius or more.

【００２９】例えば、具体的には、アルカリ金属の塩と
してホウ砂あるいはその無水塩である四ホウ酸ナトリウ
ムを白金容器内で８００℃以上に加熱して溶融する。結
晶水の無い四ホウ酸ナトリウムの方が高純度試薬が入手
しやすいし、結晶水の脱離に際して飛散が起こらないの
で便利である。他のアルカリ化合物、例えばＮａＣｌ、
ＮａＯＨ等も同様に利用することが出来る。アルカリ溶
融の容器としては、白金製の容器を好適に用いることが
出来る。For example, specifically, borax or its anhydrous salt sodium tetraborate as an alkali metal salt is heated to 800 ° C. or higher in a platinum container and melted. Sodium tetraborate without water of crystallization is more convenient because a high-purity reagent is easily available, and no scattering occurs when water of crystallization is released. Other alkaline compounds such as NaCl,
Similarly, NaOH or the like can be used. A container made of platinum can be preferably used as the alkali melting container.

【００３０】溶融した塩を、室温まで冷却すると固体の
アルカリ塩となる。このものは希薄な酸の水溶液、例え
ば希塩酸や希硝酸などで容易に溶解できる。溶解を助け
るために沸騰しない程度に加熱することは好ましい。When the molten salt is cooled to room temperature, it becomes a solid alkali salt. This product can be easily dissolved in a dilute aqueous solution of acid, for example, dilute hydrochloric acid or dilute nitric acid. It is preferable to heat to a degree that does not boil to aid dissolution.

【００３１】以上で得られた水溶液を、通常の方法で定
容にし、溶けた不純物濃度を測定する。本発明の方法で
特に重要な元素であるジルコニウム（Ｚｒ）を分析する
場合には、ＩＣＰ−ＡＥＳ（プラズマ発光法）を好適に
用いることが出来る。The aqueous solution obtained above is brought to a constant volume by a usual method, and the concentration of dissolved impurities is measured. When analyzing zirconium (Zr) which is a particularly important element in the method of the present invention, ICP-AES (plasma emission method) can be preferably used.

【００３２】本発明方法で好適に用いられる精製手段と
しては、前記結晶質天然石英原料をハロゲン元素含有雰
囲気中で加熱することをあげることができる。また、本
発明における不純物測定対象としてはジルコニウム元素
をあげることができ、このジルコニウム元素の含有量を
所定値、好ましくは０．８ｐｐｍ以下に設定することに
より、高純度の石英ガラス、例えばシリコン単結晶引上
げ用石英ガラスルツボを得ることができる。As a refining means preferably used in the method of the present invention, heating the crystalline natural quartz raw material in an atmosphere containing a halogen element can be mentioned. Further, zirconium element can be cited as an impurity measurement target in the present invention, and by setting the content of this zirconium element to a predetermined value, preferably 0.8 ppm or less, high-purity quartz glass, for example, silicon single crystal A quartz glass crucible for pulling up can be obtained.

【００３３】本発明の高純度石英ガラス、例えばシリコ
ン単結晶引上げ用石英ガラスルツボの製造は常法により
行なえばよいが、例えば垂直軸の回りに回転する耐熱性
の型の中に石英原料粉を充填し、内側から加熱溶融する
ことによって製造することができる。The high-purity quartz glass of the present invention, for example, a quartz glass crucible for pulling a silicon single crystal, may be manufactured by a conventional method. For example, the quartz raw material powder is placed in a heat-resistant mold rotating about a vertical axis. It can be manufactured by filling and heating and melting from the inside.

【実施例】次に実施例に基づいて本発明をさらに詳細に
説明するが、本発明はこれらの例によって何ら限定され
るものではない。The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

【００３４】実施例１ ペグマタイト鉱床から選鉱、精製された石英ガラス製造
用天然石英粉を、塩素と塩化水素ガスを通じながら、１
１５０℃での滞留時間が１時間のロータリーキルン内
で、連続熱処理する。Example 1 Natural quartz powder for producing quartz glass, which was beneficiated and refined from a pegmatite deposit, was passed through 1 while passing chlorine and hydrogen chloride gas.
Continuous heat treatment is carried out in a rotary kiln with a residence time of 1 hour at 150 ° C.

【００３５】１０ロット分の処理後の石英粉から各々分
析用サンプルを採集し、このうち５グラムを２５ｍｌの
５０％フッ化水素酸と共に密閉容器に収め、１６０℃で
４時間加熱して加圧酸分解する。冷却後、目には見えな
い未溶融のＺｒ含有パーティクルをも失わないように注
意しながら白金皿に分解液を移し、硫酸を２〜３滴加え
て硫酸白煙が出るまで乾固する。Samples for analysis were collected from each of the processed quartz powders for 10 lots, 5 g of which was placed in a closed container together with 25 ml of 50% hydrofluoric acid, and heated at 160 ° C. for 4 hours and pressurized. Acid decomposes. After cooling, the decomposition solution was transferred to a platinum dish, taking care not to lose invisible unmelted Zr-containing particles, and 2 to 3 drops of sulfuric acid was added to dry the mixture until white sulfuric acid smoke appeared.

【００３６】無水硼酸ナトリウム（Ｎａ2 Ｂ4 Ｏ7 ）２
グラムを加えて８００℃以上に加熱して乾固後の残留物
を融解する。冷却した融解物を希塩酸で溶解し、純水で
５０ｍｌに定容してこの水溶液をＩＣＰ−ＡＥＳ（プラ
ズマ発光法）でジルコニウム（Ｚｒ）元素含有量を分析
測定する。Anhydrous sodium borate (Na 2 B 4 O 7 ) 2
Add gram and heat to above 800 ° C. to melt the residue after drying to dryness. The cooled melt is dissolved in dilute hydrochloric acid, and the purified solution is adjusted to a volume of 50 ml with pure water. The zirconium (Zr) element content of this aqueous solution is analyzed and measured by ICP-AES (plasma emission method).

【００３７】ジルコニウム（Ｚｒ）含有量が０．５ない
し０．７ｐｐｍの石英粉原料のロットを選別して、垂直
軸の周りに回転する耐熱性の型の中に該石英原料粉を充
填し、内側から加熱溶融してシリコン単結晶引上げ用ル
ツボを２０個溶融成型した。A lot of quartz powder raw material having a zirconium (Zr) content of 0.5 to 0.7 ppm is selected, and the quartz raw material powder is filled in a heat-resistant mold rotating about a vertical axis, Twenty crucibles for pulling a silicon single crystal were melt-molded by heating and melting from the inside.

【００３８】得られたルツボについて、そのジルコニウ
ム（Ｚｒ）含有量を測定したが、ルツボのすべてが０．
５ないし０．７ｐｐｍの範囲のジルコニウム（Ｚｒ）含
有量のものであった。The zirconium (Zr) content of the obtained crucible was measured.
It had a zirconium (Zr) content in the range of 5 to 0.7 ppm.

【００３９】比較例１ 実施例１と同様に、ペグマタイト鉱床から選鉱、精製さ
れた石英ガラス製造用天然石英粉を、塩素と塩化水素ガ
スを通じながら、１１５０℃での滞留時間が１時間のロ
ータリーキルン内で、連続熱処理した。Comparative Example 1 In the same manner as in Example 1, natural quartz powder for producing quartz glass, which was beneficiated and refined from a pegmatite deposit, was passed through a rotary kiln having a residence time of 1 hour at 1150 ° C. while passing chlorine and hydrogen chloride gas. Then, the continuous heat treatment was performed.

【００４０】処理を行った後の石英粉中のジルコニウム
（Ｚｒ）元素含有量を従来の分析方法で測定した。すな
わち、処理後の石英粉５グラムを２５ｍｌの５０％フッ
化水素酸と共に密閉容器に収め、１６０℃で４時間加熱
して加圧酸分解する。冷却後、白金皿に分解液を移し、
硫酸を２〜３滴加えて硫酸白煙が出るまで乾固する。残
留物を希塩酸で回収し、純水で５０ｍｌに定容してこの
水溶液をＩＣＰ−ＡＥＳ（プラズマ発光法）でジルコニ
ウム（Ｚｒ）元素含有量を分析測定する。The zirconium (Zr) element content in the quartz powder after the treatment was measured by a conventional analysis method. That is, 5 g of the treated quartz powder is placed in a closed container together with 25 ml of 50% hydrofluoric acid, and heated at 160 ° C. for 4 hours to undergo acid decomposition under pressure. After cooling, transfer the decomposition solution to a platinum dish,
Add 2-3 drops of sulfuric acid and dry to white smoke of sulfuric acid. The residue is recovered with dilute hydrochloric acid, the volume of the purified solution is adjusted to 50 ml with pure water, and the zirconium (Zr) element content of this aqueous solution is analyzed and measured by ICP-AES (plasma emission method).

【００４１】すべてのロットについて観測されたジルコ
ニウム（Ｚｒ）の分析値は、分析の定量下限値である
０．２ｐｐｍ以下であった。この石英粉原料を用いて、
垂直軸の周りに回転する耐熱性の型の中に該石英原料粉
を充填し、内側から加熱溶融してシリコン単結晶引上げ
用ルツボを２０個溶融成型した。The analytical values of zirconium (Zr) observed in all lots were 0.2 ppm or less, which is the lower limit of quantification in the analysis. Using this quartz powder raw material,
The quartz raw material powder was filled in a heat-resistant mold rotating around a vertical axis, and heat-melted from the inside to melt-mold 20 crucibles for pulling a silicon single crystal.

【００４２】得られたルツボについて、そのジルコニウ
ム（Ｚｒ）含有量を測定した。その結果、０．５ないし
０．８ｐｐｍの範囲のＺｒ含有量のルツボが１４個で、
０．９ないし１．２ｐｐｍの範囲のＺｒ含有量のルツボ
が６個であった。 実施例２ 上記実施例１で作ったジルコニウム（Ｚｒ）含有量の異
なるルツボを用いて公称直径８インチのシリコン単結晶
を引き上げた。Ｚｒ含有量が０．５から０．８ｐｐｍの
ものでは連続して３本の単結晶を引き上げることが出来
た。The zirconium (Zr) content of the obtained crucible was measured. As a result, 14 crucibles having a Zr content in the range of 0.5 to 0.8 ppm were obtained,
There were 6 crucibles with a Zr content in the range 0.9 to 1.2 ppm. Example 2 A silicon single crystal having a nominal diameter of 8 inches was pulled using the crucibles having different zirconium (Zr) contents prepared in Example 1 above. When the Zr content was 0.5 to 0.8 ppm, three single crystals could be continuously pulled up.

【００４３】比較例２ 上記比較例１で作ったジルコニウム（Ｚｒ）含有量の異
なるルツボを用いて実施例２と同様にシリコン単結晶を
引き上げた。Ｚｒ含有量が０．９ｐｐｍから１．２ｐｐ
ｍのルツボを用いた場合は１本目の単結晶は正常に引き
上げることが出来たが、２本目の引上げ中に結晶に粒界
が導入されてしまい、引上げを中断した。再びこの状態
で、単結晶を引き上げようとしたが種付けがうまくゆか
ず残りのシリコン溶湯は廃棄せざるをえなかった。Comparative Example 2 A silicon single crystal was pulled in the same manner as in Example 2 using the crucibles having different zirconium (Zr) contents prepared in Comparative Example 1 above. Zr content from 0.9ppm to 1.2pp
When the crucible of m was used, the first single crystal could be pulled normally, but grain boundaries were introduced into the crystal during pulling of the second, and pulling was interrupted. In this state again, we tried to pull up the single crystal, but the seeding did not go well, and the remaining silicon melt had to be discarded.

【００４４】本発明の石英ガラスの製造方法によると、
原料水晶粉の精製工程にハロゲンガス雰囲気中での加熱
処理を組み合わせ採用しても、原料粉の段階でジルコニ
ウム（Ｚｒ）含有量を正しく簡便で安価に分析できるの
で、ジルコニウム（Ｚｒ）に関して所望の純度のルツボ
を効率良く製造することが出来る。According to the method for producing quartz glass of the present invention,
Even if a heat treatment in a halogen gas atmosphere is used in combination in the refining process of the raw material crystal powder, the zirconium (Zr) content can be correctly, easily and inexpensively analyzed at the stage of the raw material powder. A crucible of high purity can be efficiently manufactured.

【００４５】こうして製造したジルコニウム含有量が
０．８ｐｐｍ以下のルツボを用いると公称口径が８イン
チのような大口径単結晶が複数本連続して引き上げられ
るようになる。When the crucible having a zirconium content of 0.8 ppm or less produced in this manner is used, a plurality of large diameter single crystals having a nominal diameter of 8 inches can be continuously pulled up.

【００４６】[0046]

【発明の効果】以上述べたごとく、本発明によれば、天
然石英を原料として高純度、特にジルコニウム（Ｚｒ）
が少なくかつ安価に石英ガラスを製造することが可能と
なるという大きな効果が達成される。As described above, according to the present invention, high purity, particularly zirconium (Zr), is obtained by using natural quartz as a raw material.
The great effect that quartz glass can be manufactured at low cost and at low cost is achieved.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 前川 清貴 福井県武生市北府２丁目１番５号 株式 会社福井環境分析センター内 (72)発明者 辻 忠左衛門 福井県武生市北府２丁目１番５号 株式 会社福井環境分析センター内 (72)発明者 斉藤 学 福井県武生市北府２丁目１番５号 株式 会社福井環境分析センター内 (56)参考文献 特開 平７−72056（ＪＰ，Ａ) 特開 平４−108683（ＪＰ，Ａ) 特開 昭48−69794（ＪＰ，Ａ) 特開 平５−273132（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C03B 20/00 C01B 33/18 C03C 3/06 G01N 1/28 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyotaka Maekawa 2-5-5 Kitafu, Takefu-shi, Fukui Prefecture Fukui Environmental Analysis Center (72) Inventor Tadazaji Tsuji 2-chome Kitafu, Takefu-shi, Fukui Fukui Environmental Analysis Center Co., Ltd. (72) Inventor Manabu Saito 2-15, Kitafu, Takefu City, Fukui Prefecture Fukui Environmental Analysis Center (56) Reference JP-A-7-72056 (JP, A) Kaihei 4-108683 (JP, A) JP 48-69794 (JP, A) JP 5-273132 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) C03B 20 / 00 C01B 33/18 C03C 3/06 G01N 1/28

Claims (5)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 結晶質天然石英を加熱溶融して製造する
天然石英ガラスの製造方法において、該結晶質天然石英
原料を一つ以上の単位精製手段の組み合わせを順次実施
して精製するにあたり、所定の単位精製手段を実施後に
当該石英原料の一部を分析のために抜き取り、これをフ
ッ化水素酸或いはフッ化水素酸と他の無機酸との混酸で
分解した後、その分解液をそのままあるいは他の無機酸
を更に添加した後に蒸発乾固し、残留物にアルカリ金属
の塩または水酸化物を加えて加熱溶融し、その後このア
ルカリ金属の塩または水酸化物を無機酸水溶液または純
水で溶解して、該溶液中の不純物を定量分析することに
よって、結晶質天然石英中の不純物含有量を求め、この
不純物含有量が所定の値以下である精製結晶質天然石英
を原料として加熱溶融によって高純度石英ガラスを製造
することを特徴とする高純度石英ガラスの製造方法。1. In a method for producing natural quartz glass, which is produced by heating and melting crystalline natural quartz, the crystalline natural quartz raw material is purified by sequentially performing a combination of one or more unit refining means. After carrying out the unit refining means of, a part of the quartz raw material is extracted for analysis and decomposed with hydrofluoric acid or a mixed acid of hydrofluoric acid and other inorganic acid, and then the decomposed solution as it is or After further adding another inorganic acid, evaporate to dryness, add an alkali metal salt or hydroxide to the residue and heat and melt, and then add the alkali metal salt or hydroxide with an inorganic acid aqueous solution or pure water. By dissolving and quantitatively analyzing the impurities in the solution, the content of impurities in the crystalline natural quartz is obtained, and the purified crystalline natural quartz whose content of impurities is equal to or less than a predetermined value is heated and melted. A method for producing high-purity quartz glass, which comprises producing high-purity quartz glass by melting. 【請求項２】 前記所定の単位精製手段が前記結晶質天
然石英原料をハロゲン元素含有雰囲気中で加熱すること
であり、結晶質天然石英中の分析対象不純物がジルコニ
ウム元素であることを特徴とする請求項１記載の高純度
石英ガラスの製造方法。2. The predetermined unit refining means is to heat the crystalline natural quartz raw material in a halogen element-containing atmosphere, and the impurity to be analyzed in the crystalline natural quartz is zirconium element. The method for producing high-purity quartz glass according to claim 1. 【請求項３】 前記精製結晶質天然石英中のジルコニウ
ム元素の含有量が０．８ｐｐｍ以下であることを特徴と
する請求項２記載の高純度石英ガラスの製造方法。3. The method for producing high-purity quartz glass according to claim 2, wherein the zirconium element content in the purified crystalline natural quartz is 0.8 ppm or less. 【請求項４】 ジルコニウム元素の含有量が０．８ｐｐ
ｍ以下である精製結晶質天然石英を原料として請求項３
記載の製造方法により製造されかつジルコニウム元素の
含有量が０．８ｐｐｍ以下であることを特徴とする高純
度石英ガラス。4. The content of zirconium element is 0.8 pp.
A purified crystalline natural quartz having a size of m or less is used as a raw material.
A high-purity quartz glass produced by the production method described above and having a zirconium element content of 0.8 ppm or less. 【請求項５】 請求項４記載の高純度石英ガラスであ
り、垂直軸の回りに回転する型の中に充填した前記精製
結晶質天然石英粉を内側から加熱溶融して製造されるこ
とを特徴とするシリコン単結晶引上げ用石英ガラスルツ
ボ。5. The high-purity quartz glass according to claim 4, which is produced by heating and melting from inside the purified crystalline natural quartz powder filled in a mold rotating about a vertical axis. A quartz glass crucible for pulling a silicon single crystal.
JP06111896A 1996-03-18 1996-03-18 High purity quartz glass and method for producing the same Expired - Lifetime JP3408917B2 (en)

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JP3408917B2 true JP3408917B2 (en) 2003-05-19

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JP6681269B2 (en) * 2016-05-19 2020-04-15 クアーズテック株式会社 Quartz glass crucible
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