JP2012001415A - Method for manufacturing quartz glass - Google Patents

Method for manufacturing quartz glass Download PDF

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JP2012001415A
JP2012001415A JP2010140769A JP2010140769A JP2012001415A JP 2012001415 A JP2012001415 A JP 2012001415A JP 2010140769 A JP2010140769 A JP 2010140769A JP 2010140769 A JP2010140769 A JP 2010140769A JP 2012001415 A JP2012001415 A JP 2012001415A
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sintering
furnace
glass
quartz
quartz glass
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Moriaki Negishi
司明 根岸
Yuichi Oga
裕一 大賀
Tadashi Enomoto
正 榎本
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Sumitomo Electric Industries Ltd
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
    • C03B19/1415—Reactant delivery systems
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
    • C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
    • C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
    • C03B19/1461—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering for doping the shaped article with flourine
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
    • C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Glass Melting And Manufacturing (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively manufacturing a quartz glass with large diameter having excellent transmittance and transmittance retention without using a large quartz furnace.SOLUTION: There is provided the method for manufacturing the quartz glass 4 that forms a transparent glass by sintering a deposited body 1 of glass fine particles having a diameter of 300 mm or larger. The method includes: a soot deposition step "a" of generating the deposited body 1 of glass fine particles by depositing silica fine particles; a first sintering step "b" for obtaining a temporary sintered body 2 by sintering the deposited body 1 of glass fine particle obtained in the soot deposition step in a heating furnace B excluding the quartz furnace C; a second sintering step "c" of obtaining the sintered body (quartz glass base material) 3 by additionally sintering the temporary sintered body 2 obtained in the first sintering step "b"; and a fluorine adding step of performing fluorine adding in one of the soot deposition step "a", the first sintering step "b" and the second sintering step "c", or in all steps.

Description

本発明は、光学系部材の材料として用いられる石英ガラスの製造方法に関する。   The present invention relates to a method for producing quartz glass used as a material for an optical system member.

石英ガラスは、例えば、集積回路等のパターンを露光・転写するのに用いられるステッパの照明系、投影系に使用される光学系部材の材料として知られている。特に、下記特許文献１に記載のように、シリカガラス微粒子堆積体を堆積し、焼結された石英ガラスにあっては、高純度であり、大口径の光学系部材においても高い透過性を備えるため、短波長を用いたステッパ等の光学系部材の材料として多く用いられている。   Quartz glass is known as a material of an optical system member used for an illumination system and a projection system of a stepper used for exposing and transferring a pattern of an integrated circuit, for example. In particular, as described in Patent Document 1 below, silica glass deposited and sintered quartz glass has high purity and high transparency even in a large-diameter optical system member. Therefore, it is often used as a material for optical system members such as steppers using short wavelengths.

２００１−３２２８１９号公報No. 2001-322819

前述した石英ガラスの製造における焼結工程では、現在、石英炉心管を用いた石英炉が多く用いられているが、高純度、且つ大口径の光学系部材を得るための口径を有する石英ガラスを製造するには、焼結時の収縮を考慮した直径のガラス微粒子堆積体が必要であるため、大径の石英炉心管を備えた大型の石英炉が必要である。しかしながら、このような大型の石英炉は、焼結時の熱により石英炉心管が変形したり割れたりする可能性があり、作業上扱い難い上に、石英炉心管を含む石英部品が高価であるため、大口径の石英ガラスの製造コストが高くなってしまうという問題があった。石英炉心管以外の炉としては、石英炉心管より安価に大型化が可能なカーボン炉心管を用いたカーボン炉があるが、カーボン炉でガラス母材を焼結すると、カーボンによる還元反応により、製造された石英ガラス内に酸素欠乏欠陥が生じ、短波長の紫外域の透過率が悪化する、という問題があった。   In the above-described sintering process in the production of quartz glass, a quartz furnace using a quartz furnace core tube is currently used in many cases. However, quartz glass having a diameter for obtaining a high-purity and large-diameter optical system member is used. For manufacturing, a glass fine particle deposit having a diameter in consideration of shrinkage during sintering is required, and therefore a large quartz furnace having a large diameter quartz furnace core tube is required. However, in such a large quartz furnace, there is a possibility that the quartz furnace core tube may be deformed or cracked due to heat during sintering, and it is difficult to handle in operation, and quartz parts including the quartz furnace core tube are expensive. Therefore, there has been a problem that the manufacturing cost of large-diameter quartz glass is increased. As a furnace other than a quartz furnace core tube, there is a carbon furnace that uses a carbon furnace core tube that can be made larger in size at a lower cost than a quartz furnace core tube, but when a glass base material is sintered in a carbon furnace, it is produced by a reduction reaction with carbon. There is a problem in that oxygen-deficient defects are generated in the quartz glass and the transmittance in the short wavelength ultraviolet region is deteriorated.

本発明は、このような問題に対処することを課題とするものである。すなわち、大型の石英炉を使用することなく大口径の石英ガラスを製造できること、カーボン炉のように石英ガラス内に酸素欠乏欠陥が生じてしまうような炉を使用したとしても、短波長の紫外域の透過性に優れた石英ガラスを製造できること、大口径の短波長の紫外域の透過性に優れた石英ガラスの製造において低コスト化できること、等が本発明の目的である。   An object of the present invention is to deal with such a problem. That is, it is possible to produce a large-diameter quartz glass without using a large quartz furnace, and even when using a furnace such as a carbon furnace in which oxygen-deficient defects occur in the quartz glass, the ultraviolet region of the short wavelength It is an object of the present invention to be able to produce quartz glass having excellent transparency and to reduce the cost in producing quartz glass having excellent transparency in the ultraviolet region with a large diameter and short wavelength.

このような目的を達成するために、本発明による石英ガラスの製造方法は、以下の構成を少なくとも具備するものである。   In order to achieve such an object, a method for producing quartz glass according to the present invention comprises at least the following configuration.

直径３００mm以上の外径のガラス微粒子堆積体を焼結して透明ガラス化する石英ガラスの製造方法において、シリカ微粒子を堆積させて前記ガラス微粒子堆積体を生成するスス付け工程と、前記スス付け工程で得られた前記ガラス微粒子堆積体を、石英炉を除く加熱炉で焼結して仮焼結体を得る第１焼結工程と、前記第１焼結工程で得られた前記仮焼結体を石英炉で更に焼結して焼結体を得る第２焼結工程と、前記スス付け工程、前記第１焼結工程、前記第２焼結工程のいずれか一つ又は二つの工程、或いは全ての工程において、フッ素を添加するフッ素添加工程を備えたことを特徴とする。   In a method for producing quartz glass in which a glass fine particle deposit having an outer diameter of 300 mm or more is sintered to form a transparent glass, a sooting step of depositing silica fine particles to generate the glass fine particle deposit, and the sooting step A first sintering step for obtaining a temporary sintered body by sintering the glass fine particle deposit obtained in step 1 in a heating furnace excluding a quartz furnace, and the temporary sintered body obtained in the first sintering step. A second sintering step in which the sintered body is further sintered in a quartz furnace to obtain a sintered body, and one or two steps of the sooting step, the first sintering step, the second sintering step, or All the steps are characterized by having a fluorine addition step of adding fluorine.

本発明の第１焼結工程に用いる加熱炉は、カーボン炉が好ましく、また、第１焼結工程における内圧を300Pa以下とすることが好ましい。また、石英ガラスのフッ素濃度が500wtppm以上となるような添加量であることが好ましい。   The heating furnace used in the first sintering step of the present invention is preferably a carbon furnace, and the internal pressure in the first sintering step is preferably 300 Pa or less. Moreover, it is preferable that the addition amount is such that the fluorine concentration of quartz glass is 500 wtppm or more.

本発明によれば、石英炉以外の加熱炉による第１焼結工程により焼結された仮焼結体を、スス付け工程で生成されたガラス微粒子堆積体の外径よりも小径となるようにある程度収縮させた後に、石英炉による第２焼結工程でこの仮焼結体をさらに焼結するので、大型の石英炉を使用することなく大口径の石英ガラスを製造できる。また、石英炉以外の加熱炉で最後まで焼結するのではなく、後半の焼結は石英炉で行うので、石英ガラス内に欠陥を生じず、短波長の紫外域の透過性に優れた石英ガラスを製造できる。このように、石英炉としては小規模なものを使用し、大型母材を焼結することができるので、大口径な石英ガラスの製造においても低コスト化することができる。   According to the present invention, the pre-sintered body sintered in the first sintering step using a heating furnace other than the quartz furnace has a smaller diameter than the outer diameter of the glass fine particle deposit formed in the sooting step. After shrinking to some extent, this temporary sintered body is further sintered in a second sintering step using a quartz furnace, so that a large-diameter quartz glass can be produced without using a large quartz furnace. In addition, since the latter half of the sintering is performed in a quartz furnace rather than in a heating furnace other than the quartz furnace, the quartz glass has no defects in the quartz glass and has excellent transparency in the short wavelength ultraviolet region. Glass can be manufactured. Thus, since a small-sized quartz furnace can be used and a large base material can be sintered, cost can be reduced even in the production of large-diameter quartz glass.

本発明に係る石英ガラスの製造方法を示す工程図であり、（ａ）はスス付け工程、（ｂ）は第１焼結工程、（ｃ）は第２焼結工程、（ｄ）は（ｃ）で製造された石英ガラス母材、（ｅ）は石英ガラス母材を加工してなる石英ガラスを夫々示す。It is process drawing which shows the manufacturing method of the quartz glass which concerns on this invention, (a) is a sooting process, (b) is a 1st sintering process, (c) is a 2nd sintering process, (d) is (c) The quartz glass base material manufactured in (1) and (e) respectively show quartz glass formed by processing the quartz glass base material. 第１焼結工程における適正加熱温度及び適正加熱時間を示すグラフ。The graph which shows the appropriate heating temperature and the appropriate heating time in a 1st sintering process. 第１焼結工程において適正加熱温度及び適正加熱時間で仮焼結を行って製造した石英ガラスと、この適正加熱温度及び適正加熱時間から外れた温度及び時間で仮焼結を行って製造した石英ガラスとの紫外透過率曲線。Quartz glass manufactured by performing preliminary sintering at a proper heating temperature and proper heating time in the first sintering step, and quartz manufactured by performing preliminary sintering at a temperature and time deviating from the proper heating temperature and proper heating time. UV transmittance curve with glass.

本発明の石英ガラスの製造方法は、直径３００mm以上の外径のガラス微粒子堆積体を焼結して透明ガラス化する石英ガラスの製造方法において、シリカ微粒子を堆積させて前記ガラス微粒子堆積体を生成するスス付け工程と、前記スス付け工程で得られた前記ガラス微粒子堆積体を、石英炉を除く加熱炉で焼結して仮焼結体を得る第１焼結工程と、前記第１焼結工程で得られた前記仮焼結体を石英炉で更に焼結して焼結体を得る第２焼結工程と、前記スス付け工程、前記第１焼結工程、前記第２焼結工程のいずれか一つ又は二つの工程、或いは全ての工程において、フッ素を添加するフッ素添加工程を備えている。   The method for producing quartz glass of the present invention is a method for producing quartz glass in which a glass fine particle deposit having an outer diameter of 300 mm or more is sintered to form a transparent glass. In this method, silica fine particles are deposited to produce the glass fine particle deposit. A sooting step, a first sintering step of obtaining a temporary sintered body by sintering the glass fine particle deposit obtained in the sooting step in a heating furnace excluding a quartz furnace, and the first sintering A second sintering step in which the preliminary sintered body obtained in the step is further sintered in a quartz furnace to obtain a sintered body, the sooting step, the first sintering step, and the second sintering step. In any one or two steps, or in all steps, a fluorine addition step of adding fluorine is provided.

本発明の第１焼結工程に用いる加熱炉は、石英炉を除くものであって、更に、焼結時の収縮を考慮した直径のガラス微粒子堆積体を焼結できるような、安価な材質の大型炉が好ましく、例えば、カーボン炉やセラミック炉等が挙げられる。また、第１焼結工程において焼結効率を考慮すると、第１焼結工程における内圧を300Pa以下とすることが好ましく、より好ましくは、50Pa〜200Paである。   The heating furnace used in the first sintering step of the present invention is one other than a quartz furnace, and is made of an inexpensive material that can sinter a glass particle deposit having a diameter that takes into account shrinkage during sintering. A large furnace is preferable, and examples thereof include a carbon furnace and a ceramic furnace. In consideration of the sintering efficiency in the first sintering step, the internal pressure in the first sintering step is preferably 300 Pa or less, more preferably 50 Pa to 200 Pa.

石英ガラスに高い透過性を備えさせるためには、フッ素を添加することが効果的であることから、前述のスス付け工程、第１焼結工程、第２焼結工程のいずれか一つ又は二つの工程、或いは全ての工程において、少なくとも、１種のフッ素化合物を含むガスを導入することで、石英ガラスにフッ素を添加するが、このフッ素の添加量は、石英ガラスのフッ素濃度が500wtppm以上となるような添加量であることが好ましい。   In order to provide quartz glass with high permeability, it is effective to add fluorine. Therefore, any one or two of the above-mentioned sooting step, first sintering step, and second sintering step are effective. In one process or all processes, fluorine is added to quartz glass by introducing a gas containing at least one fluorine compound. The amount of fluorine added is such that the fluorine concentration of quartz glass is 500 wtppm or more. It is preferable that the addition amount be such that

本発明でいうフッ素化合物は、例えば、SiF4 、SF6 、CHF3 、CF4 、F2 等が挙げられる。 Examples of the fluorine compound used in the present invention include SiF 4 , SF 6 , CHF 3 , CF 4 , and F 2 .

本発明で製造される石英ガラスは、短波長を用いたステッパ等の露光機に用いられる光学系部材の材料として好適なものであり、例えば、ＹＡＧレーザ等の固体レーザを用いた加工機、或いはドライ洗浄等に用いられる紫外線エキシマランプ等にも適用される光学系部材の材料として好適な、透過性に優れた高純度の石英ガラスである。   The quartz glass produced in the present invention is suitable as a material for an optical system member used in an exposure machine such as a stepper using a short wavelength. For example, a processing machine using a solid laser such as a YAG laser, or It is a high-purity quartz glass excellent in transparency and suitable as a material for an optical system member applied to an ultraviolet excimer lamp or the like used for dry cleaning or the like.

以下、本発明に係る石英ガラスの製造方法の実施形態を説明する。本実施形態の石英ガラスは、次の各工程により製造される。   Hereinafter, an embodiment of a method for producing quartz glass according to the present invention will be described. The quartz glass of this embodiment is manufactured by the following steps.

スス付け工程（図１（ａ））
スス付け工程では、ガラス微粒子堆積体１をスス付け法により製造する。すなわち、排気装置Ａ１を有する反応容器Ａ内において、少なくとも、ガラス原料と水素ガスと酸素ガスとをバーナＡ２に供給し、バーナＡ２が噴出する酸水素火炎中でガラス微粒子を生成させ、生成したガラス微粒子（以下「スス」という）を、鉛直方向に引き上げながら軸方向を中心として回転する出発棒Ａ３に対して堆積（以下「スス付け」という）させて、ガラス微粒子堆積体１を製造する。具体的なスス付け法としては、ＶＡＤ（気相軸付け）、ＯＶＤ法などが用いられる。 Sooting process (Fig. 1 (a))
In the sooting step, the glass fine particle deposit 1 is manufactured by a sooting method. That is, in the reaction vessel A having the exhaust device A1, at least glass raw material, hydrogen gas, and oxygen gas are supplied to the burner A2, and glass fine particles are generated in an oxyhydrogen flame ejected by the burner A2. Fine particles (hereinafter referred to as “soot”) are deposited (hereinafter referred to as “soot”) on the starting rod A3 that rotates about the axial direction while being pulled up in the vertical direction, thereby producing a glass fine particle deposit 1. As a specific sooting method, VAD (vapor phase axis attaching), OVD method or the like is used.

第１焼結工程（図１（ｂ））
スス付け工程で製造されたガラス微粒子堆積体１を、加熱炉Ｂに挿入して加熱することにより、仮焼結体２を形成する。この第１焼結工程では、焼結過程において、ガラス微粒子堆積体１が径方向に収縮しながら焼結され、少なくとも、仮焼結体２の直径が石英炉Ｃに挿入可能な直径（ガラス微粒子堆積体１の径の７０％程度）となるまで収縮するように焼結を行う。加熱炉Ｂは、大口径の石英ガラスとなるガラス微粒子堆積体１が挿入可能な大きさのものであり、直径３００mm程度以上の径を有し、同様のガラス微粒子堆積体１が挿入可能な高価な大型の石英炉よりも安価なものである。例としてカーボン炉、或いはセラミック炉等が挙げられる。尚、第１焼結工程は、以下では仮焼結とも称する。 First sintering step (FIG. 1 (b))
The glass fine particle deposit 1 produced in the sooting process is inserted into the heating furnace B and heated to form the temporary sintered body 2. In this first sintering step, in the sintering process, the glass fine particle deposit 1 is sintered while contracting in the radial direction, and at least the diameter of the temporary sintered body 2 is a diameter that can be inserted into the quartz furnace C (glass fine particles). Sintering is performed so as to shrink until it reaches about 70% of the diameter of the deposit 1. The heating furnace B is of a size that allows insertion of a glass fine particle deposit 1 that is a large-diameter quartz glass, has a diameter of about 300 mm or more, and is expensive to allow insertion of the same glass fine particle deposit 1. It is cheaper than a large quartz furnace. Examples include a carbon furnace or a ceramic furnace. In addition, a 1st sintering process is also called temporary sintering below.

第２焼結工程（図１（ｃ））
第１焼結工程で製造された仮焼結体２を、石英炉Ｃに挿入して加熱して更に焼結することにより、透明な円柱状の石英ガラス母材３となる（図１（ｄ））。この石英ガラス母材３を、所定厚及び所定径に研削することにより、円板状の石英ガラス４を複数製造することができる（図１（ｅ））。この第２焼結工程で使用される石英炉Ｃは、第２焼結工程によって焼結された仮焼結体２を挿入可能な大きさのものであり、通常の口径の石英ガラスを製造可能な直径で形成されたガラス微粒子堆積体が挿入可能なものであればよく、それほど大きなものは必要としない。 Second sintering step (FIG. 1 (c))
The temporary sintered body 2 manufactured in the first sintering step is inserted into a quartz furnace C, heated and further sintered, whereby a transparent cylindrical quartz glass base material 3 is obtained (FIG. 1 (d). )). By grinding the quartz glass base material 3 to a predetermined thickness and a predetermined diameter, a plurality of disc-shaped quartz glasses 4 can be manufactured (FIG. 1 (e)). The quartz furnace C used in the second sintering step is of a size that allows the provisional sintered body 2 sintered in the second sintering step to be inserted, and can produce quartz glass having a normal diameter. Any glass particle deposit formed with a large diameter may be inserted, and not so large.

本実施形態では、前述のスス付け工程、第１焼結工程、第２焼結工程のいずれか一つ又は二つの工程、或いは全ての工程において、少なくとも、１種のフッ素化合物を含むガスを導入することで、石英ガラスにフッ素を添加するフッ素添加工程がある（図示せず）。   In this embodiment, a gas containing at least one kind of fluorine compound is introduced in any one or two of the above-mentioned sooting step, first sintering step, second sintering step, or all steps. Thus, there is a fluorine addition step of adding fluorine to quartz glass (not shown).

前述の石英ガラスの製造方法によると、高価な大型の石英炉を用いることなく、193nm域の光の初期透過率が90.0%以上、193nm域の光の透過維持率が99.6%以上の石英ガラス４を製造することができる。   According to the method for producing quartz glass described above, quartz glass 4 having an initial transmittance of 90.0% or more for light in the 193 nm region and a transmittance maintenance factor of 99.6% or more for light in the 193 nm region without using an expensive large quartz furnace. Can be manufactured.

以下、実施例を挙げて本発明を具体的に説明する。本実施例では、本発明の製造方法を用いて製造した石英ガラス４を実施例１及び実施例２とし、本発明の製造方法を用いずに製造した石英ガラスを比較例１及び比較例２とした。尚、本実施例は本発明の範囲を限定するものではない。   Hereinafter, the present invention will be specifically described with reference to examples. In this example, the quartz glass 4 manufactured using the manufacturing method of the present invention is referred to as Example 1 and Example 2, and the quartz glass manufactured without using the manufacturing method of the present invention is referred to as Comparative Example 1 and Comparative Example 2. did. In addition, a present Example does not limit the scope of the present invention.

＜比較方法＞
本発明の製造方法を用いて製造した石英ガラス４（実施例１、２）と、本発明の製造方法を用いずに製造した石英ガラス（比較例１、２）との、波長１９３nmにおける光の透過率及び透過率維持率を測定し、この測定した値を比較する。 <Comparison method>
The quartz glass 4 manufactured using the manufacturing method of the present invention (Examples 1 and 2) and the quartz glass manufactured without using the manufacturing method of the present invention (Comparative Examples 1 and 2) The transmittance and the transmittance maintenance rate are measured, and the measured values are compared.

尚、以下の実施例１、２及び比較例１、２では、フッ素化合物を含むガスの導入を前述のスス付け工程において行った。また、実施例１、２及び比較例１、２で用いられる加熱炉Ｂは、カーボン炉である。   In Examples 1 and 2 and Comparative Examples 1 and 2 below, introduction of a gas containing a fluorine compound was performed in the above-described sooting step. Moreover, the heating furnace B used in Examples 1 and 2 and Comparative Examples 1 and 2 is a carbon furnace.

＜実施例１＞
スス付け工程：ＶＡＤ法を用いて直径が300mm、成長軸方向の長さが1,000mmとなるようにガラス微粒子堆積体１を作製した。この直径のガラス微粒子堆積体１は、大口径の石英ガラスを製造可能なものである。本実施例では、フッ素化合物を含むガスの導入量は1.5リットル/minである。 <Example 1>
Sooting step: The glass fine particle deposit 1 was prepared using the VAD method so that the diameter was 300 mm and the length in the growth axis direction was 1,000 mm. The glass fine particle deposit 1 having this diameter can produce a large-diameter quartz glass. In this embodiment, the introduction amount of the gas containing the fluorine compound is 1.5 liter / min.

第１焼結工程：ガラス微粒子堆積体１をカーボン炉に挿入し、1380℃で40分間焼結して直径が220mm、成長軸方向の長さが900mmの仮焼結体２を得た。この第１焼結工程では、Heガスで炉内圧100Paとして行い、第１焼結工程の時間はHeガス置換から取出しまで４時間であった。   First sintering step: The glass fine particle deposit 1 was inserted into a carbon furnace and sintered at 1380 ° C. for 40 minutes to obtain a temporary sintered body 2 having a diameter of 220 mm and a growth axis direction length of 900 mm. In this first sintering step, the pressure in the furnace was set to 100 Pa with He gas, and the time of the first sintering step was 4 hours from the replacement of He gas to the removal.

第２焼結工程：仮焼結体２を石英炉Ｃに挿入し、Heガスを25リットル/minの量で導入しながら、1530℃まで昇温して2mm/minの下降速度で熱処理して焼結することで透明な石英ガラス母材（直径150mm、成長軸方向の長さ500mm）３を得た。   Second sintering step: The preliminary sintered body 2 is inserted into the quartz furnace C and heated to 1530 ° C. while introducing He gas at a rate of 25 liters / min and heat-treated at a descending rate of 2 mm / min. By sintering, a transparent quartz glass base material (diameter 150 mm, growth axis direction length 500 mm) 3 was obtained.

＜実施例２＞
実施例２は、スス付け工程におけるフッ素化合物を含むガスの導入量を0.4リットル/minとした以外の各工程おける焼結条件を、実施例１の焼結条件と同じとして、透明な石英ガラス母材（直径150mm、成長軸方向の長さ500mm）３を得た。 <Example 2>
Example 2 is the same as the sintering conditions of Example 1 except that the introduction amount of the gas containing the fluorine compound in the sooting process was 0.4 liter / min. A material 3 (diameter 150 mm, growth axis direction length 500 mm) 3 was obtained.

＜比較例１＞
比較例１は、スス付け工程におけるフッ素化合物を含むガスの導入量を0.1/minとした以外の各工程おける焼結条件を、実施例１の焼結条件と同じとして、透明な石英ガラス母材（直径150mm、成長軸方向の長さ500mm）を得た。 <Comparative Example 1>
Comparative Example 1 is a transparent quartz glass base material in which the sintering conditions in each step other than the introduction amount of the gas containing the fluorine compound in the sooting step are set to 0.1 / min, are the same as the sintering conditions in Example 1. (Diameter 150 mm, length in the growth axis direction 500 mm) was obtained.

＜比較例２＞
比較例２は、カーボン炉のみで、ガラス微粒子堆積体を焼結して透明な石英ガラス母材を得るものである。具体的には、スス付け工程においてフッ素化合物を含むガスを1.0リットル/minの量で導入しながら、直径が300mm、成長軸方向の長さが1,000mmとなるようにガラス微粒子堆積体を作製した。次いで、このガラス微粒子堆積体をカーボン炉に挿入し、1300℃で30分、次いで1350℃で30分、最後に1500℃の40分の熱処理を行って焼結することで、透明な石英ガラス母材（直径150mm、成長軸方向の長さ500mm）を得た。この比較例２では、カーボン炉内には、Heガスは流さず炉内圧を10Pa以下として焼結を行い、焼結の時間は取出しまで4時間であった。 <Comparative example 2>
In Comparative Example 2, only a carbon furnace is used to sinter the glass particulate deposit to obtain a transparent quartz glass base material. Specifically, while introducing a gas containing a fluorine compound in an amount of 1.0 liter / min in the sooting process, a glass particulate deposit was produced so that the diameter was 300 mm and the length in the growth axis direction was 1,000 mm. . Next, this glass particulate deposit is inserted into a carbon furnace and sintered by heat treatment at 1300 ° C. for 30 minutes, then at 1350 ° C. for 30 minutes, and finally at 1500 ° C. for 40 minutes. A material (diameter 150 mm, growth axis length 500 mm) was obtained. In this comparative example 2, the He gas was not flowed into the carbon furnace and the furnace pressure was 10 Pa or less, and the sintering was performed for 4 hours until the removal.

実施例１、２で得られた石英ガラス母材３及び比較例１、２で得られた石英ガラス母材の、波長193nmにおける初期透過率（厚さ10mmに換算）、ArFエキシマレーザを照射し、その照射後の透過率維持率、フッ素濃度を測定した結果を表１に示す。ArFエキシマレーザの照射条件は、120mJ@100Hz x 3時間でガラス面実際照射強度は、12.8mJ/pulse/cm2に相当する。   The quartz glass base material 3 obtained in Examples 1 and 2 and the silica glass base material obtained in Comparative Examples 1 and 2 were irradiated with an initial transmittance at a wavelength of 193 nm (converted to a thickness of 10 mm) and an ArF excimer laser. Table 1 shows the results of measuring the transmittance maintenance ratio and the fluorine concentration after the irradiation. The irradiation condition of ArF excimer laser is 120 mJ @ 100 Hz × 3 hours, and the actual irradiation intensity on the glass surface corresponds to 12.8 mJ / pulse / cm 2.

Figure 2012001415
Figure 2012001415

表１に示すように、実施例１、２の製造方法で製造された石英ガラス母材３の波長１９３nmにおける光の初期透過率及び透過率維持率は、各々９０％以上、９９．６％以上となっており、短波長の紫外線用光学部材に使用する上で問題ない透過特性を示していることがわかった。このように、本実施形態の石英ガラスの製造方法によれば、大型の石英炉を用いなくとも、大口径の石英ガラス母材を、小口径の石英ガラス母材と同等の透過特性で製造することができる。   As shown in Table 1, the initial transmittance and transmittance maintenance ratio of light at a wavelength of 193 nm of the quartz glass base material 3 manufactured by the manufacturing methods of Examples 1 and 2 are 90% or more and 99.6% or more, respectively. Thus, it has been found that it has a transmission characteristic that is not problematic when used for an optical member for ultraviolet rays having a short wavelength. Thus, according to the quartz glass manufacturing method of the present embodiment, a large-diameter quartz glass base material is manufactured with the same transmission characteristics as a small-diameter quartz glass base material without using a large quartz furnace. be able to.

また、比較例１のように、カーボン炉における仮焼結を行い、石英炉で焼結して透明な石英ガラス母材を得ても、得られた石英ガラス母材のフッ素濃度が低いと、実施例１、２よりも波長１９３nmにおける光の初期透過率及び透過率維持率が低下するという結果となった。フッ素を含有しているとSi-F結合ができるため、酸素欠乏欠陥（Si-Si結合、163nmの吸収）が生じるのを抑制することが可能であるが、比較例１では、フッ素濃度が低かったため、この効果が十分ではなくなり、吸収が生じて透過率が低下したものと考えられる。   Further, as in Comparative Example 1, pre-sintering in a carbon furnace, and even in a quartz furnace to obtain a transparent quartz glass base material, if the fluorine concentration of the obtained quartz glass base material is low, As a result, the initial transmittance and transmittance maintenance rate of light at a wavelength of 193 nm were lower than those of Examples 1 and 2. Since fluorine-containing Si-F bonds can be formed, oxygen deficiency defects (Si-Si bonds, absorption at 163 nm) can be suppressed. In Comparative Example 1, the fluorine concentration is low. For this reason, it is considered that this effect is not sufficient, absorption occurs, and transmittance decreases.

また、比較例２のように、全焼結工程をカーボン炉のみで行えば、実施例１、２のようにカーボン炉及び石英炉を用いた製造方法、或は、高価な大型の石英炉を用いた製造方法に比べて低コスト化できるが、製造された石英ガラスの初期透過率及び透過率維持率が、実施例１、２で製造された石英ガラス４よりも低下するという結果となった。これは、カーボン炉のカーボンによる還元反応により、前述した酸素欠乏欠陥が生じるため、フッ素が十分に添加されていたとしても前述したフッ素の効果が十分ではなくなり、吸収が生じて透過率が低下したものと考えられる。   Further, if the entire sintering process is performed only in the carbon furnace as in Comparative Example 2, a manufacturing method using the carbon furnace and the quartz furnace as in Examples 1 and 2, or an expensive large quartz furnace is used. Although the cost could be reduced as compared with the manufacturing method that was used, the initial transmittance and transmittance maintenance rate of the manufactured quartz glass were lower than those of the quartz glass 4 manufactured in Examples 1 and 2. This is because the oxygen deficiency defect described above occurs due to the reduction reaction by carbon in the carbon furnace, so even if fluorine is sufficiently added, the effect of fluorine described above is not sufficient, absorption occurs, and the transmittance decreases. It is considered a thing.

更に、第１焼結工程における製造条件について詳細検討した結果を図２、図３に示す。図２に示すように、カーボン炉での仮焼結において温度と保持時間（焼結時間）が一定の範囲（枠Ｄで囲んだ範囲）を外れると、図３の一点鎖線に示すように163nmの吸収が生じてしまうことがわかった。この163nmの吸収は、前述した酸素欠乏欠陥によるものと考えられる。すなわち、カーボン炉での焼結時間が長すぎたり、温度が高すぎたりすると、たとえ、フッ素が添加されていたとしても、酸素欠乏欠陥が生じて、透過率が低下してしまう。前述した比較例２のように、カーボン炉のみで最後までガラス化させた場合も、焼結過程で焼結温度と保持時間が一定の範囲を越えてしまうため、実施例１、２で製造された石英ガラス４よりも初期透過率及び透過率維持率が低下した石英ガラスとなる。   Furthermore, the result of having examined in detail about the manufacturing conditions in a 1st sintering process is shown in FIG. 2, FIG. As shown in FIG. 2, when the temperature and the holding time (sintering time) are out of a certain range (a range surrounded by the frame D) in the preliminary sintering in the carbon furnace, as shown by a one-dot chain line in FIG. It has been found that the absorption of. This absorption at 163 nm is considered to be due to the oxygen deficiency defect described above. That is, if the sintering time in the carbon furnace is too long or the temperature is too high, even if fluorine is added, oxygen deficiency defects occur and the transmittance decreases. As in Comparative Example 2 described above, even when vitrified only with a carbon furnace, the sintering temperature and holding time exceed a certain range during the sintering process. The quartz glass has a lower initial transmittance and transmittance maintenance rate than the quartz glass 4.

すなわち、カーボン炉における仮焼結の温度と保持時間を図２に示す枠Ｄ内の範囲で行い、石英炉で更に焼結させた透明な石英ガラス母材３を得て、得られた石英ガラス母材３のフッ素濃度が570wtppm以上となるようにすることによって、高価な大型の石英炉を用いることなく、初期透過率90.0%以上、透過率維持率99.6%以上となる石英ガラス４を製造することができる。したがって、初期透過率及び透過率維持率に優れた石英ガラス４の製造を低コスト化でき、この石英ガラス４を安価に提供することができる。   That is, the temperature and holding time of pre-sintering in the carbon furnace are performed within the range within the frame D shown in FIG. 2, and the transparent quartz glass base material 3 further sintered in the quartz furnace is obtained. By making the fluorine concentration of the base material 3 to be 570 wtppm or more, the quartz glass 4 having an initial transmittance of 90.0% or more and a transmittance maintenance factor of 99.6% or more is manufactured without using an expensive large-sized quartz furnace. be able to. Therefore, the production of the quartz glass 4 excellent in the initial transmittance and the transmittance maintenance rate can be reduced in cost, and the quartz glass 4 can be provided at a low cost.

各工程の焼結条件は、例示した条件に限定するものではなく、良好な初期透過率及び透過率維持率となる範囲で変更することができる。例えば、カーボン炉の内圧が低すぎると（例えば比較例２のように10Pa以下）であると、真空度が強すぎてしまい還元作用が増強されるものと考えられるため、カーボン炉内圧は50Pa以上が好ましいと思われる。逆に、カーボン炉の内圧が高すぎると（例えば300Pa以上）、収縮焼結に時間がかかってしまうため、200Pa以下が好ましいと思われる。   The sintering conditions in each step are not limited to the exemplified conditions, and can be changed within a range where good initial transmittance and transmittance maintenance ratio are obtained. For example, if the internal pressure of the carbon furnace is too low (for example, 10 Pa or less as in Comparative Example 2), it is considered that the degree of vacuum is too strong and the reduction action is enhanced. Seems to be preferable. On the contrary, if the internal pressure of the carbon furnace is too high (for example, 300 Pa or more), it will take time for shrinkage sintering, so 200 Pa or less is preferable.

また、石英ガラス４のフッ素濃度については、前述したように570wtppm以上で良好な初期透過率及び透過率維持率を備えることができるため、少なくとも、500wtppm以上が好ましいと思われる。   Further, as described above, the fluorine concentration of the quartz glass 4 is preferably at least 500 wtppm because it can provide good initial transmittance and transmittance maintenance rate at 570 wtppm or more as described above.

尚、本発明は、例示した実施の形態に限定するものでは無く、特許請求の範囲の各項に記載された内容から逸脱しない範囲の構成による実施が可能である。   It should be noted that the present invention is not limited to the illustrated embodiments, and can be implemented with configurations within a range that does not deviate from the contents described in the respective claims.

１：ガラス微粒子堆積体 ２：仮焼結体 ３：石英ガラス母材 ４：石英ガラス
Ａ：反応容器 Ｂ：加熱炉（カーボン炉） Ｃ：石英炉 1: Glass particulate deposit 2: Temporary sintered body 3: Quartz glass base material 4: Quartz glass A: Reaction vessel B: Heating furnace (carbon furnace) C: Quartz furnace

スス付け工程(図１（ａ）)
スス付け工程では、ガラス微粒子堆積体１をスス付け法により製造する。すなわち、排気装置Ａ１を有する反応容器Ａ内において、少なくとも、ガラス原料と水素ガスと酸素ガスとをバーナＡ２に供給し、バーナＡ２が噴出する酸水素火炎中でガラス微粒子を生成させ、生成したガラス微粒子(以下「スス」という)を、鉛直方向に引き上げながら軸方向を中心として回転する出発棒Ａ３に対して堆積（以下「スス付け」という）させて、ガラス微粒子堆積体１を製造する。具体的なスス付け法としては、ＶＡＤ（気相軸付け）法、ＯＶＤ法などが用いられる。 Sooting process (Fig. 1 (a))
In the sooting step, the glass fine particle deposit 1 is manufactured by a sooting method. That is, in the reaction vessel A having the exhaust device A1, at least glass raw material, hydrogen gas, and oxygen gas are supplied to the burner A2, and glass fine particles are generated in an oxyhydrogen flame ejected by the burner A2. Fine glass particles (hereinafter referred to as “soot”) are deposited (hereinafter referred to as “soot”) on the starting rod A3 that rotates about the axial direction while being pulled up in the vertical direction, and the glass fine particle deposit 1 is manufactured. As a specific sooting method, a VAD (vapor phase axis attaching) method , an OVD method, or the like is used.

第２焼結工程(図１（ｃ）)
第１焼結工程で製造された仮焼結体２を、石英炉Ｃに挿入して加熱して更に焼結することにより、透明な円柱状の石英ガラス母材３となる（図１（ｄ））。この石英ガラス母材３を、所定厚及び所定径に研削することにより、円板状の石英ガラス４を複数製造することができる（図１（ｅ））。この第２焼結工程で使用される石英炉Ｃは、第１焼結工程によって焼結された仮焼結体２を挿入可能な大きさのものであり、通常の口径の石英ガラスを製造可能な直径で形成されたガラス微粒子堆積体が挿入可能なものであればよく、それほど大きなものは必要としない。 Second sintering step (Fig. 1 (c))
The temporary sintered body 2 manufactured in the first sintering step is inserted into a quartz furnace C, heated and further sintered, whereby a transparent cylindrical quartz glass base material 3 is obtained (FIG. 1 (d). )). By grinding the quartz glass base material 3 to a predetermined thickness and a predetermined diameter, a plurality of disc-shaped quartz glasses 4 can be manufactured (FIG. 1 (e)). The quartz furnace C used in the second sintering step is of a size that allows the provisional sintered body 2 sintered in the first sintering step to be inserted, and can produce quartz glass having a normal diameter. Any glass particle deposit formed with a large diameter may be inserted, and not so large.

Claims (4)

直径３００mm以上の外径のガラス微粒子堆積体を焼結して透明ガラス化する石英ガラスの製造方法において、シリカ微粒子を堆積させて前記ガラス微粒子堆積体を生成するスス付け工程と、前記スス付け工程で得られた前記ガラス微粒子堆積体を、石英炉を除く加熱炉で焼結して仮焼結体を得る第１焼結工程と、前記第１焼結工程で得られた前記仮焼結体を石英炉で更に焼結して焼結体を得る第２焼結工程と、前記スス付け工程、前記第１焼結工程、前記第２焼結工程のいずれか一つ又は二つの工程、或いは全ての工程において、フッ素を添加フッ素添加工程と、を備えていることを特徴とする石英ガラスの製造方法。   In a method for producing quartz glass in which a glass fine particle deposit having an outer diameter of 300 mm or more is sintered to form a transparent glass, a sooting step of depositing silica fine particles to generate the glass fine particle deposit, and the sooting step A first sintering step for obtaining a temporary sintered body by sintering the glass fine particle deposit obtained in step 1 in a heating furnace excluding a quartz furnace, and the temporary sintered body obtained in the first sintering step. A second sintering step in which the sintered body is further sintered in a quartz furnace to obtain a sintered body, and one or two steps of the sooting step, the first sintering step, the second sintering step, or A method for producing quartz glass, comprising a step of adding fluorine in all steps, and a step of adding fluorine. 前記加熱炉がカーボン炉であることを特徴とする請求項１記載の石英ガラスの製造方法。   The method for producing quartz glass according to claim 1, wherein the heating furnace is a carbon furnace. 前記第１焼結工程における内圧が300Pa以下であることを特徴とする請求項１又は２記載の石英ガラスの製造方法。   The method for producing quartz glass according to claim 1 or 2, wherein an internal pressure in the first sintering step is 300 Pa or less. 前記第２焼結工程で焼結された前記焼結体のフッ素濃度が500wtppm以上となるように、前記フッ素を添加することを特徴とする請求項１乃至３いずれか１項記載の石英ガラスの製造方法。   The quartz glass according to any one of claims 1 to 3, wherein the fluorine is added so that a fluorine concentration of the sintered body sintered in the second sintering step is 500 wtppm or more. Production method.
JP2010140769A 2010-06-21 2010-06-21 Method for manufacturing quartz glass Pending JP2012001415A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019089508A1 (en) * 2017-10-30 2019-05-09 Corning Incorporated Halogen-doped silica for optical fiber preforms

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019089508A1 (en) * 2017-10-30 2019-05-09 Corning Incorporated Halogen-doped silica for optical fiber preforms

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