JP2000191329A - Production of optical quartz glass for excimer laser - Google Patents

Production of optical quartz glass for excimer laser

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Publication number
JP2000191329A
JP2000191329A JP10371084A JP37108498A JP2000191329A JP 2000191329 A JP2000191329 A JP 2000191329A JP 10371084 A JP10371084 A JP 10371084A JP 37108498 A JP37108498 A JP 37108498A JP 2000191329 A JP2000191329 A JP 2000191329A
Authority
JP
Japan
Prior art keywords
quartz glass
excimer laser
atmosphere
glass body
producing
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.)
Granted
Application number
JP10371084A
Other languages
Japanese (ja)
Other versions
JP4011217B2 (en
Inventor
Akira Fujinoki
朗 藤ノ木
Takayuki Oshima
隆之 大嶋
Hiroyuki Nishimura
裕幸 西村
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
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Shin Etsu Quartz Products Co Ltd filed Critical Shin Etsu Quartz Products Co Ltd
Priority to JP37108498A priority Critical patent/JP4011217B2/en
Priority to PCT/EP1999/010282 priority patent/WO2000039038A1/en
Publication of JP2000191329A publication Critical patent/JP2000191329A/en
Application granted granted Critical
Publication of JP4011217B2 publication Critical patent/JP4011217B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • 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
    • 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
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/07—Impurity concentration specified
    • C03B2201/075—Hydroxyl ion (OH)
    • 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
    • C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
    • C03B2201/21—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with molecular hydrogen
    • 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
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
    • C03C2201/21—Doped silica-based glasses containing non-metals other than boron or halide containing molecular hydrogen
    • 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
    • C03C2203/50—After-treatment
    • C03C2203/52—Heat-treatment
    • C03C2203/54—Heat-treatment in a dopant containing atmosphere
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Landscapes

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

Abstract

PROBLEM TO BE SOLVED: To obtain an optical quartz glass having high transmittance and laser resistance by including a process for forming a porous silica base material, a process for obtaining a quartz glass body by heating in an oxidizing atmosphere and a process for heating the resulting quartz glass body in a reducing atmosphere. SOLUTION: A high purity volatile silicon compound such as silicon tetrachloride is subjected to flame hydrolysis and formed soot-like silica is deposited on a heat resistant substrate. The resulting porous silica base material is transparently vitrified by heating in an oxidizing atmosphere at 1,400-1,600 deg.C to form a quartz glass body. A gaseous mixture of oxygen and an inert gas such as He is used as the oxidizing atmosphere. The oxygen content is preferably 30 to <100 vol.%. The glass body is homogenized by holding at a high temperature of >=1,600 deg.C for a long time. After shaping, the glass body is heated to 600-1,500 deg.C in a reducing atmosphere. A mixed atmosphere of hydrogen and other inert gas is used as the reducing atmosphere. The glass body is then annealed by holding in the air at 1,100-1,200 deg.C for >=10 hr and slow cooling at <=50 deg.C/hr rate.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、エキシマレーザー用光
学石英ガラスの製造方法、詳しくはエキシマレーザー光
を光源とするリソグラフィー装置の光学系に使用する光
学用石英ガラスの製造方法、さらに詳しくはＡｒＦエキ
シマレーザーリソグラフィー装置のレンズ、プリズム、
ビームスプリッター等の光学系に使用する合成石英ガラ
スの製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing optical quartz glass for excimer lasers, and more particularly to a method for producing optical quartz glass for use in an optical system of a lithography apparatus using excimer laser light as a light source. Excimer laser lithography system lenses, prisms,
The present invention relates to a method for producing synthetic quartz glass used for an optical system such as a beam splitter.

【０００２】[0002]

【従来の技術】近年、ＬＳＩの高集積化とともに、ウェ
ーハ上に描く集積回路のパターンも微細化の一途をたど
り、クオーターミクロン（０．２５μｍ）以下の超微細
パターンが描画された超ＬＳＩの量産化が始まりだして
いる。このような超微細パターンを得るには、それを描
画する露光光源も短波長化する必要があり、エキシマレ
ーザー光を光源とするステッパーが開発され、既にＫｒ
Ｆエキシマレーザー光（波長２４８ｎｍ）を光源とする
ステッパーが実用化され、さらに次世代のステッパーと
してＡｒＦエキシマレーザー光（波長１９３ｎｍ）を光
源とするステッパーが注目を集めている。このＫｒＦエ
キシマレーザー光やＡｒＦエキシマレーザー光のような
短波長領域においても十分な透過性を示す硝材としては
石英ガラスや蛍石等が挙げられるが、中でも高純度の揮
発性珪素化合物を火炎加水分解し、生成するすす状シリ
カを透明ガラス化して得た合成石英ガラスは、２６０ｎ
ｍ以下の波長領域でも高い透過性を示すところから、エ
キシマレーザー光を光源とするリソグラフィー用光学材
料として好適である。2. Description of the Related Art In recent years, with the increasing integration of LSI, the pattern of an integrated circuit drawn on a wafer has been steadily miniaturized, and mass production of an ultra LSI having an ultra-fine pattern of quarter micron (0.25 μm) or less has been drawn. Has begun. In order to obtain such an ultrafine pattern, it is necessary to shorten the wavelength of an exposure light source for drawing the pattern, and a stepper using an excimer laser beam as a light source has been developed.
A stepper using an F excimer laser beam (wavelength 248 nm) as a light source has been put to practical use, and a stepper using an ArF excimer laser beam (wavelength 193 nm) as a light source has attracted attention as a next-generation stepper. Quartz glass and fluorite are examples of glass materials that exhibit sufficient transparency even in a short wavelength region such as KrF excimer laser light and ArF excimer laser light. Among them, flame-hydrolysis of high-purity volatile silicon compounds is preferred. The synthetic quartz glass obtained by converting the soot-like silica to be vitrified into a transparent glass is 260 n
Since it shows high transmittance even in a wavelength region of m or less, it is suitable as an optical material for lithography using an excimer laser beam as a light source.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら、上記合
成石英ガラスにＫｒＦエキシマレーザーやＡｒＦエキシ
マレーザー等のエキシマーレーザー光を長時間照射する
と、該エキシマレーザーが寿命２０ｎ秒程度のパルス光
で時間当りのエネルギーが高いため合成石英ガラス中に
Ｅ’ｃｅｎｔｅｒやＮＢＯＨＣと呼ばれる常磁性欠陥が
生成し、長期の安定性に欠ける問題があった。この問題
を解決する方法として、合成石英ガラス体に水素をドー
プする方法が特開平３−８８７４２号で提案されてい
る。しかしこの方法では合成石英ガラスの製造段階で還
元性欠陥が発生することがあり、この還元性欠陥がエキ
シマレーザ光により容易に分解されて常磁性欠陥を生
じ、これが波長２１５ｎｍに吸収バンドを生じ、エキシ
マレーザー光、特にＡｒＦエキシマレーザー光の透過率
を著しく低下させる不具合があった。前記常磁性欠陥
は、石英ガラス組織（ＳｉＯ２）中のＳｉが化学量論以
下の酸素と結合した欠陥である酸素欠損型欠陥等の欠陥
であるが、この常磁性欠陥の発生を防止するため石英ガ
ラスを酸素を含む雰囲気で６００℃〜１５００℃の温度
で酸化処理したのち、３００℃〜６００℃で水素含有雰
囲気中で処理する光学用石英ガラスの製造方法が特開平
６−１６６５２８号公報で提案されている。前記方法で
は常磁性欠陥の治癒がみられるが、熱処理が多段階に渡
るところから、不純物が外部から拡散し合成石英ガラス
を汚染しその透過率を低下させる上に、水素含有雰囲気
中の処理温度が３００℃〜６００℃と低温であるため、
水素の合成石英ガラス体への拡散速度が小さく大型の石
英ガラス部材を作成する場合、非常に時間がかかる欠点
を有していた。特に、近年、露光面積の拡大に伴い使用
される大口径化、肉厚化した光学系を前記温度範囲で水
素処理しても数箇月以上を要し工業的実施が不可能であ
った。さらに、前記と同様に合成石英ガラス塊を酸化処
理し、次いで水素処理する石英ガラスの製造方法が特許
第２５６６１５１号公報で提案されているが、この製造
方法では石英ガラス塊を酸化処理するところから最近の
大口径化し、肉厚化した光学部材中の酸素欠損欠陥が十
分に除去できない欠点があった。こうした事情から、大
口径化し、肉厚化した光学系であってもエキシマレーザ
ー光、特にＡｒＦエキシマレーザーに対して優れた透過
率を有するとともに、耐レーザー性の高い光学部材の提
案が熱望されているのが現状である。However, when the above synthetic quartz glass is irradiated with an excimer laser beam such as a KrF excimer laser or an ArF excimer laser for a long time, the excimer laser emits a pulse light having a life of about 20 ns and energy per hour. Therefore, paramagnetic defects called E'center and NBOHC are generated in the synthetic quartz glass, and there is a problem that long-term stability is lacking. As a method for solving this problem, a method of doping hydrogen into a synthetic quartz glass body has been proposed in Japanese Patent Application Laid-Open No. 3-88742. However, in this method, reducing defects may be generated at the stage of manufacturing synthetic quartz glass, and these reducing defects are easily decomposed by excimer laser light to generate paramagnetic defects, which generate absorption bands at a wavelength of 215 nm. There is a problem that the transmittance of excimer laser light, particularly ArF excimer laser light, is significantly reduced. The paramagnetic defect is a defect such as an oxygen-deficient defect, which is a defect in which Si in a quartz glass structure (SiO 2 ) is combined with oxygen having a stoichiometry or less. In order to prevent the occurrence of this paramagnetic defect. Japanese Patent Application Laid-Open No. 6-166528 discloses a method for producing optical quartz glass in which quartz glass is oxidized in an atmosphere containing oxygen at a temperature of 600 ° C. to 1500 ° C., and then treated at 300 ° C. to 600 ° C. in a hydrogen-containing atmosphere. Proposed. In the above method, although the paramagnetic defect is cured, the impurity is diffused from the outside to contaminate the synthetic quartz glass to reduce the transmittance, and the treatment temperature in the hydrogen-containing atmosphere is increased because the heat treatment is performed in multiple stages. Is as low as 300 ° C to 600 ° C,
In the case of producing a large quartz glass member having a low diffusion rate of hydrogen into the synthetic quartz glass body, it has a disadvantage that it takes a very long time. In particular, in recent years, even if a large-diameter and thick-walled optical system used with an increase in an exposure area is subjected to hydrogen treatment in the above-mentioned temperature range, it takes several months or more, and industrial implementation was impossible. Furthermore, a method of manufacturing quartz glass in which a synthetic quartz glass lump is oxidized and then hydrogen-treated in the same manner as described above is proposed in Japanese Patent No. 2566151. However, in this manufacturing method, the quartz glass lump is oxidized. There has been a defect that oxygen deficiency defects in recently enlarged and thickened optical members cannot be sufficiently removed. Under these circumstances, there has been a keen demand for a proposal for an optical member having high transmittance to excimer laser light, particularly ArF excimer laser, and high laser resistance even in an optical system having a large diameter and a large thickness. That is the current situation.

【０００４】そこで、本発明者等は、鋭意研究を続けた
結果、合成石英ガラスを水素処理した時に生じる還元性
欠陥を効率的に治癒するには予め石英ガラス中に酸素過
剰型欠陥を作成しておき、次いで水素処理をするのが有
効であることを見出した。そしてその際、バルクの石英
ガラスでは酸素の拡散が非常に小さいところから、高純
度の揮発性珪素化合物を火炎加水分解して生成したすす
状シリカを堆積して得た多孔質シリカ母材（以下スート
体という）に酸化処理を施こすとともに処理温度を８０
０℃以上とすることで、大型の石英ガラス体であっても
内部まで十分に酸素が拡散し、酸素過剰型欠陥が生成
し、それを６００℃を超える温度で水素処理しても還元
性欠陥が生成することがなく、かつ水素分子が高濃度に
ドープされ、エキシマレーザー光、特にＡｒＦエキシマ
レーザー光に対し高い透過率を有するとともに、耐レー
ザー性に優れた光学用石英ガラスが製造できることを見
出して本発明を完成したものである。すなわち、The inventors of the present invention have conducted intensive studies, and as a result, in order to efficiently cure reducing defects generated when a synthetic quartz glass is subjected to hydrogen treatment, oxygen-deficient defects were previously formed in quartz glass. In advance, it has been found that it is effective to perform hydrogen treatment. At that time, since the diffusion of oxygen is very small in the bulk quartz glass, a porous silica base material (hereinafter, referred to as a porous silica base material) obtained by depositing soot-like silica produced by flame hydrolysis of a high-purity volatile silicon compound. The soot body is oxidized and the treatment temperature is 80
By setting the temperature at 0 ° C. or higher, oxygen diffuses sufficiently inside even a large quartz glass body to generate oxygen-excess type defects, which are reduced even if hydrogen treatment is performed at a temperature exceeding 600 ° C. Was found to be able to produce quartz glass for optics that is highly doped with excimer laser light, especially ArF excimer laser light, and that has excellent laser resistance, without the formation of hydrogen, and the high concentration of hydrogen molecules. Thus, the present invention has been completed. That is,

【０００５】本発明は、高い透過性を有するとともに優
れた耐レーザー性を有するエキシマレーザー用光学石英
ガラスの製造方法を提供することを目的とする。An object of the present invention is to provide a method for producing an optical quartz glass for an excimer laser having high transmittance and excellent laser resistance.

【０００６】また、本発明は、ＡｒＦエキシマレーザー
光に対して高い透過率を示すとともに、耐レーザー性に
優れた大口径、肉厚のＡｒＦエキシマレーザー用光学石
英ガラスの製造方法を提供することを目的とする。Another object of the present invention is to provide a method for producing a large-diameter, thick-walled optical quartz glass for an ArF excimer laser, which has high transmittance to ArF excimer laser light and has excellent laser resistance. Aim.

【０００７】[0007]

【課題を解決するための手段】上記目的を達成する本発
明は、高純度の揮発性珪素化合物を火炎加水分解して生
成するすす状シリカを基体上に堆積させて多孔質シリカ
母材を形成する工程、該多孔質シリカ母材を酸化性雰囲
気中で加熱し透明ガラス化し石英ガラス体を得る工程、
及び還元性雰囲気中で熱処理する工程を含むことを特徴
とするエキシマレーザー用光学石英ガラスの製造方法に
係る。SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a porous silica matrix by depositing soot-like silica produced by flame hydrolysis of a high-purity volatile silicon compound on a substrate. A step of heating the porous silica base material in an oxidizing atmosphere to form a transparent glass to obtain a quartz glass body,
And a step of performing heat treatment in a reducing atmosphere.

【０００８】上記高純度の揮発性珪素化合物としては、
例えば四塩化珪素、メチルトリメトキシシラン、テトラ
メトキシシラン等が挙げられ、これらを火炎加水分解し
て生成したすす状シリカを回転する耐熱性基体上に堆積
することで多孔質シリカ母材が形成される。前記多孔質
シリカ母材は続いて酸化性雰囲気中で加熱され透明ガラ
ス化されるが、その加熱温度は１４００℃以上１６００
℃以下の範囲がよい。好ましくは酸化性雰囲気中で１０
００〜１４００℃で多孔質シリカ母材を仮焼結し緻密化
したのち不活性ガス雰囲気中で１４００℃〜１６００℃
に加熱するのがよい。この酸化性雰囲気中での処理で酸
素過剰型欠陥を有する石英ガラス体が製造される。前記
酸素過剰型欠陥とは、石英ガラス組織（ＳｉＯ２）のＳ
ｉが化学量論以上に酸素と結合した欠陥をいう。酸化性
雰囲気で使用するガスとしては、酸素と他の不活性ガ
ス、例えばＨｅ、Ｎ２ガスとの混合ガスが用いられる
が、特にＨｅガスが好ましい。前記混合ガス中の酸素の
含有量は３０ｖｏｌ％以上１００ｖｏｌ％未満がよい。
酸素の含有量が、３０ｖｏｌ％未満では酸素過剰型欠陥
が少な過ぎ還元性欠陥の治癒が十分行われず、また酸素
１００％では石英ガラス中に泡が残存することがあり好
ましくない。この酸化性雰囲気中での処理に続いて均質
化処理又は均質化処理及び成型（以下均質化処理等とい
う）が行われ、光学部材の高均質化が図られる。この均
質化処理等ですす状シリカの堆積時に発生する層状構
造、３方向の膜理等が除去されるとともに、屈折率分布
（Δｎ）が２×１０−６以下、また複屈折量が２ｎｍ／
ｃｍ以下の高均質の石英ガラスが得られる。しかし、前
記均質化処理は耐火炉中で１６００℃以上の高温に長時
間保持して行われるため、炉材、治具及び雰囲気等から
不純物が石英ガラスに拡散し、汚染が起こる。特にＮａ
による汚染が重大で、ＡｒＦエキシマレーザーの透過率
の低下に大きく影響する。そのため炉材を使用しない均
質化処理法が特開平７−２６７６６２号公報で提案され
ている。この均質化処理後成型が行われるが、この成型
で石英ガラス体は角型、円盤型、四角錐型等の光学材料
として必要な形状に形成される。前記成型は坩堝内で１
６００℃以上に石英ガラス体を加熱し、その自重または
強制力により所望の形状に変形するのが一般的であるの
で、この成型においてもＮａの熱拡散による石英ガラス
成型体の汚染が起こる。The high-purity volatile silicon compounds include:
For example, silicon tetrachloride, methyltrimethoxysilane, tetramethoxysilane and the like can be mentioned, and a porous silica matrix is formed by depositing soot-like silica produced by flame hydrolysis on a rotating heat-resistant substrate. You. The porous silica base material is subsequently heated in an oxidizing atmosphere to be transparent vitrified, and the heating temperature is 1400 ° C. or more and 1600 ° C.
The range below ° C is good. Preferably 10 in an oxidizing atmosphere
After the porous silica base material is pre-sintered and densified at 00 to 1400 ° C, it is heated to 1400 ° C to 1600 ° C in an inert gas atmosphere.
It is better to heat it. By the treatment in the oxidizing atmosphere, a quartz glass body having oxygen excess type defects is produced. The oxygen-excess type defect is defined as S in quartz glass structure (SiO 2 ).
A defect in which i is bonded to oxygen more than stoichiometric. As a gas used in the oxidizing atmosphere, a mixed gas of oxygen and another inert gas, for example, He or N 2 gas is used, but He gas is particularly preferable. The content of oxygen in the mixed gas is preferably 30 vol% or more and less than 100 vol%.
If the oxygen content is less than 30 vol%, the excess oxygen type defects are too small to sufficiently cure the reducing defects, and if the oxygen content is 100%, bubbles may remain in the quartz glass, which is not preferable. Subsequent to the treatment in the oxidizing atmosphere, homogenization treatment or homogenization treatment and molding (hereinafter, referred to as homogenization treatment or the like) are performed to achieve high homogeneity of the optical member. This homogenization treatment removes the layered structure generated during the deposition of the soot-like silica, the three-dimensional film formation, etc., and has a refractive index distribution (Δn) of 2 × 10 −6 or less and a birefringence of 2 nm /
A highly homogeneous quartz glass of less than 1 cm is obtained. However, since the homogenization treatment is performed for a long time in a refractory furnace at a high temperature of 1600 ° C. or more, impurities diffuse from the furnace material, jig, atmosphere, and the like into the quartz glass, causing contamination. Especially Na
Contamination is significant and greatly affects the decrease in the transmittance of the ArF excimer laser. Therefore, a homogenization treatment method using no furnace material has been proposed in Japanese Patent Application Laid-Open No. Hei 7-267662. After the homogenization process, molding is performed. By this molding, the quartz glass body is formed into a shape required as an optical material such as a square, a disk, or a quadrangular pyramid. The molding is performed in a crucible
Generally, the quartz glass body is heated to 600 ° C. or higher and deformed into a desired shape by its own weight or forcible force. Therefore, in this molding, contamination of the quartz glass molded body due to thermal diffusion of Na occurs.

【０００９】本発明にあっては、上記酸化性雰囲気での
加熱処理、均質化処理等に続いて還元性雰囲気中での加
熱処理が行なわれる。前記還元性雰囲気としては、水素
雰囲気、水素と他の不活性ガスとの混合雰囲気が挙げら
れ、加熱温度は６００℃〜１５００℃、好ましくは８０
０℃〜１０００℃の範囲がよい。加熱温度が６００℃未
満では処理効果が少なく、一方１５００℃を超えて実施
しても効果の向上がみれない。このような高い温度での
還元性雰囲気中での処理であっても石英ガラスに還元性
欠陥が生成せず、しかも水素分子が高濃度にドープされ
エキシマレーザーの照射に対して安定となる。このエキ
シマレーザーの照射に対しての安定性は、水素含有量に
比例して増大するので、還元性雰囲気中での加熱処理の
際加圧するのがよい。圧力は１気圧以上１０気圧以下が
よい。圧力が１０気圧を超えると高温高圧での水素処理
となり法律的な規制が生じる。前記還元性雰囲気中での
加熱処理で石英ガラス成型体が含有する酸素過剰型欠陥
は還元されてＯＨ基に変換されるとともに、水素分子が
ドープされるがその濃度は２×１０１７分子／ｃｍ ３以
上がよい。この還元性雰囲気中での加熱処理に続いてア
ニール処理が行われるが、該アニール処理は大気中で１
１００〜１２００℃の温度に１０時間以上長時間保持し
て行われる。このアニール処理後は温度６００℃まで徐
冷速度５０℃／時間以下で徐冷され、その後は自然冷却
される。徐冷速度が前記範囲を超えると徐冷中にクラッ
クが発生することがあり好ましくない。このアニール処
理では石英ガラスの徐冷点（１１２０℃）近傍の比較的
低温で行われるものの、処理時間が長いところから均質
化処理や成型時と同様に炉材や雰囲気等から不純物が拡
散し石英ガラスを汚染することになる。前記均質化処
理、成型及びアニール処理による汚染で石英ガラス成型
体中のＮａの含有量が２４〜６０ｐｐｂの範囲内であれ
ば、波長２６０ｎｍ以下の連続紫外線を長時間照射する
ことで透過率を回復でき、特にＡｒＦエキシマレーザー
光の場合、内部吸収が０．２％以内にまで回復できる。
前記連続紫外線を照射するランプとしては、主波長２５
３．７ｎｍ及び１８４．９ｎｍの低圧水銀ランプ、波長
１７２ｎｍのＸｅエキシマランプ、或は波長２２２ｎｍ
のＫｒＣｌエキシマランプが挙げられる。また、紫外線
の照度は少なくとも１ｍＷ／ｃｍ３、照射時間は５０時
間以上とするのがよい。[0009] In the present invention, in the above oxidizing atmosphere
After heating, homogenization, etc., heat treatment in a reducing atmosphere
Heat treatment is performed. As the reducing atmosphere, hydrogen
Atmosphere, mixed atmosphere of hydrogen and other inert gas
The heating temperature is 600 ° C to 1500 ° C, preferably 80 ° C.
The range of 0 ° C to 1000 ° C is good. Heating temperature is not 600 ℃
When it is full, the treatment effect is small, while on the other hand it exceeds 1500 ° C
No improvement in the effect is seen. At such high temperatures
Reduces quartz glass even when treated in a reducing atmosphere
No defects are generated and hydrogen molecules are highly doped.
It becomes stable against irradiation of excimer laser. This ex
Stability against Shima laser irradiation depends on the hydrogen content.
Since it increases in proportion, the heat treatment in a reducing atmosphere
It is better to pressurize. The pressure should be between 1 atmosphere and 10 atmosphere
Good. Hydrogen treatment at high temperature and pressure when the pressure exceeds 10 atm
And legal regulations arise. In the reducing atmosphere
Oxygen-excess type defects contained in quartz glass moldings by heat treatment
Is reduced and converted to an OH group, and a hydrogen molecule is
Doped but its concentration is 2 × 1017Molecule / cm 3Less than
The top is good. Following the heat treatment in this reducing atmosphere,
A neal process is performed, and the annealing process is performed in air for 1 hour.
Keep at a temperature of 100 ~ 1200 ° C for more than 10 hours
Done. After this annealing treatment, gradually reduce the temperature to 600 ° C.
Slow cooling at a cooling rate of 50 ° C / hour or less, and then natural cooling
Is done. If the slow cooling rate exceeds the above range,
This is not preferable because cracks may occur. This annealing process
The theory is that quartz glass is relatively cool near the annealing point (1120 ° C).
Performs at low temperature, but is homogeneous from long processing time
As in the case of chemical treatment or molding, impurities are
Scattering will contaminate the quartz glass. The homogenization process
Glass molding due to contamination from processing, molding and annealing
If the content of Na in the body is in the range of 24 to 60 ppb
For example, continuous ultraviolet light with a wavelength of 260 nm or less is irradiated for a long time.
The transmittance can be recovered by using the ArF excimer laser
In the case of light, the internal absorption can be recovered to within 0.2%.
As the lamp for irradiating the continuous ultraviolet rays, the main wavelength 25
3.7 nm and 184.9 nm low pressure mercury lamps, wavelength
172nm Xe excimer lamp or wavelength 222nm
KrCl excimer lamp. Also UV
Illumination is at least 1 mW / cm3, Irradiation time is 50 hours
It is better to make it longer than.

【００１０】[0010]

【発明の実施の形態】次に本発明の実施例について述べ
るがこれによって本発明はなんら限定されるものではな
い。DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described, but the present invention is not limited thereto.

【００１１】なお、以下の実施例及び比較例の物性値は
以下の測定方法で求めた値である。 ｉ）屈折率分布：フィーゾ型干渉計による測定法。 ｉｉ）複屈折量：直交ニコル法による測定法。 ｉｉｉ）脈理：目視。 ｉｖ）１９３ｎｍ内部透過率：１９３ｎｍにおける石英
ガラスの理論透過率９０．８６％からレイリー散乱にお
けるロスとして知れる０．１８％を減じた９０．６８％
を用いて、厚さ１０ｍｍにおける見掛け透過率Ｔ％に対
し、式（Ｔ／９０．６８）×１００より求める測定法。 ｖ）Ｎａ濃度：フレームレス原子吸光分析法による測定
法The physical properties of the following Examples and Comparative Examples are values obtained by the following measuring methods. i) Refractive index distribution: a measuring method using a Fizeau interferometer. ii) Birefringence: A measuring method by the orthogonal Nicol method. iii) Striae: visual. iv) 193 nm internal transmittance: 90.68% obtained by subtracting 0.18% known as a loss in Rayleigh scattering from 90.86% of the theoretical transmittance of quartz glass at 193 nm.
Is a method of measuring the apparent transmittance T% at a thickness of 10 mm using the formula (T / 90.68) × 100. v) Na concentration: Measurement method by flameless atomic absorption spectrometry

【００１２】[0012]

【実施例】実施例１ 四塩化珪素を酸素ガスに同伴させて酸水素火炎中に導入
し火炎加水分解して得られたすす状シリカを回転する耐
熱性基体上に堆積させスート体を得た。得られたスート
体は外部が低密度で内部が相対的に高い密度を示し、平
均的な嵩密度が１．２ｇ／ｃｍ３であった。このスート
体を酸素８０ｖｏｌ％、Ｈｅ２０ｖｏｌ％の酸化性雰囲
気内で１０００℃に加熱し８時間、密度が均一になるよ
うに仮焼結した。前記仮焼結でスート体の嵩密度は１．
５ｇ／ｃｍ３に増大し、また全体の密度分布ば低減し
た。次いで酸素５０ｖｏｌ％、Ｈｅ５０ｖｏｌ％の酸化
性雰囲気て炉内温度を１４５０℃に昇温し、スート体を
引上げながら透明ガラス化した。得られた石英ガラス体
のＯＨ濃度は２０ｐｐｍで、水素は検出されなかった。
この石英ガラス体を高純度のグラファイト坩堝内に載置
し、窒素置換した雰囲気で１８００℃に加熱し自重で外
径２５０ｍｍ、高さ１００ｍｍの円盤状に成型した。Example 1 Soot-like silica obtained by introducing silicon tetrachloride into an oxyhydrogen flame with entrained oxygen gas and subjecting it to flame hydrolysis was deposited on a rotating heat-resistant substrate to obtain a soot body. . The resulting soot body had a low density on the outside and a relatively high density on the inside, and the average bulk density was 1.2 g / cm 3 . The soot body was heated to 1000 ° C. in an oxidizing atmosphere of 80 vol% oxygen and 20 vol% He, and was temporarily sintered for 8 hours so that the density became uniform. The bulk density of the soot body was 1.
The density increased to 5 g / cm 3 and the overall density distribution decreased. Next, the temperature in the furnace was raised to 1450 ° C. in an oxidizing atmosphere of 50 vol% of oxygen and 50 vol% of He, and the soot body was vitrified while being pulled up. The OH concentration of the obtained quartz glass body was 20 ppm, and no hydrogen was detected.
The quartz glass body was placed in a high-purity graphite crucible, heated to 1800 ° C. in a nitrogen-substituted atmosphere, and molded by its own weight into a disk shape having an outer diameter of 250 mm and a height of 100 mm.

【００１３】上記成型体の周囲のグラファイトとの接触
部分を十分にＨＦエッチング処理で除去し、次いで高圧
水素処理炉中で水素１０気圧、１１００℃で２４時間加
熱して水素ローディングを実施した。該処理に引き続い
て成型体のアニール処理を行った。前記アニール処理で
は水素１気圧の雰囲気中で１１５０℃に２０時間保持
し、次いで６００℃まで５℃／ｍｉｎの降温速度で徐冷
したのち自然冷却して除歪操作を行った。得られた成型
体の屈折率分布（Δｎ）は１×１０−６、複屈折率は１
ｎｍ／ｃｍ以下で、３方向脈理や層状構造がみれなかっ
た。またＯＨ基濃度は６５ｐｐｍ、水素分子濃度は２．
５×１０１８分子／ｃｍ３であった。前記成型体から直
径６０ｍｍ、高さ１０ｍｍの試料を切り出し、透過率を
測定した。また同じ試料を用いてＡｒＦエキシマレーザ
ーを照射し、その時の透過率変化及び屈折率変化を測定
した。その結果を表１に示す。A portion of the molded body which was in contact with graphite around the graphite was sufficiently removed by HF etching, and then heated in a high-pressure hydrogen treatment furnace at 10 atm of hydrogen and at 1100 ° C. for 24 hours to carry out hydrogen loading. Subsequent to the treatment, the molded body was subjected to an annealing treatment. In the annealing treatment, the strain was maintained at 1150 ° C. for 20 hours in an atmosphere of 1 atm of hydrogen, then gradually cooled to 600 ° C. at a rate of 5 ° C./min, and then naturally cooled to remove strain. The refractive index distribution (Δn) of the obtained molded body was 1 × 10 −6 , and the birefringence was 1
At nm / cm or less, three-way striae and a layered structure were not observed. The OH group concentration is 65 ppm, and the hydrogen molecule concentration is 2.
It was 5 × 10 18 molecules / cm 3 . A sample having a diameter of 60 mm and a height of 10 mm was cut out from the molded body, and the transmittance was measured. Further, the same sample was irradiated with an ArF excimer laser, and a change in transmittance and a change in refractive index at that time were measured. Table 1 shows the results.

【００１４】実施例２ 高純度のメチルトリメトキシシランをアルゴンガスに同
伴させて酸水素火炎中に導入し火炎加水分解して得られ
たすす状シリカを回転する基体上に堆積させて、スート
体を得た。得られたスート体の平均的な嵩密度は１．３
ｇ／ｃｍ３であった。このスート体を酸素８０ｖｏｌ
％、Ｈｅ２０ｖｏｌ％の酸化性雰囲気内で９００℃で１
０時間加熱して仮焼結した。前記仮焼結でスート体の嵩
密度は１．５ｇ／ｃｍ３に増大し、また全体の密度分布
ば低減した。次いで酸素５０ｖｏｌ％、Ｈｅ５０ｖｏｌ
％の酸化性雰囲気て炉内温度を１４５０℃に昇温し、ス
ート体を引上げながら透明ガラス化した。得られた石英
ガラス体のＯＨ濃度は３０ｐｐｍで、水素は検出されな
かった。この石英ガラス体を実施例１と同様の方法で同
様な大きさに成型し、成型体の周囲のグラファイトとの
接触部分をＨＦエッチング処理で十分に除去し、次いで
高圧水素処理炉中で水素５気圧、１０００℃で３２時間
加熱して水素ローディングを施した。該処理に引き続い
て成型体のアニール処理を行った。前記アニール処理は
大気雰囲気で１１５０℃に２０時間保持した。次いで６
００℃まで５℃／ｍｉｎの降温速度で徐冷したのち自然
冷却して除歪操作を行った。得られた成型体の屈折率分
布（Δｎ）は１×１０−６、複屈折率は１ｎｍ／ｃｍ以
下で、３方向脈理や層状構造がみれなかった。またＯＨ
基濃度は８０ｐｐｍ、水素分子濃度は１．０×１０１８
分子／ｃｍ３であった。前記成型体から直径６０ｍｍ、
高さ１０ｍｍの試料を切り出し、透過率を測定した。ま
た同じ試料を用いてＡｒＦエキシマレーザーを照射し、
その時の透過率変化及び屈折率変化を測定した。その結
果を表１に示す。Example 2 A soot-like silica obtained by introducing high-purity methyltrimethoxysilane into an oxyhydrogen flame with argon gas and subjecting it to flame hydrolysis was deposited on a rotating substrate. I got The average bulk density of the obtained soot body is 1.3.
g / cm 3 . This soot body is 80 vol oxygen
%, 900 ° C in an oxidizing atmosphere of 20%
Pre-sintering was performed by heating for 0 hours. The bulk density of the soot body was increased to 1.5 g / cm 3 by the preliminary sintering, and the overall density distribution was reduced. Then oxygen 50vol%, He50vol
% In an oxidizing atmosphere, the temperature in the furnace was raised to 1450 ° C., and the soot body was pulled up and vitrified transparently. The OH concentration of the obtained quartz glass body was 30 ppm, and no hydrogen was detected. This quartz glass body was molded to the same size by the same method as in Example 1, and the portion in contact with graphite around the molded body was sufficiently removed by HF etching. Heating was carried out at 1000 ° C. for 32 hours under atmospheric pressure to carry out hydrogen loading. Subsequent to the treatment, the molded body was subjected to an annealing treatment. The annealing treatment was maintained at 1150 ° C. in an air atmosphere for 20 hours. Then 6
After gradually cooling to 00 ° C. at a temperature lowering rate of 5 ° C./min, the strain was removed by natural cooling. The obtained molded article had a refractive index distribution (Δn) of 1 × 10 −6 , a birefringence of 1 nm / cm or less, and no three-way striae or a layered structure was observed. Also OH
The base concentration is 80 ppm, and the hydrogen molecule concentration is 1.0 × 10 18
Molecules / cm 3 . 60 mm in diameter from the molded body,
A sample having a height of 10 mm was cut out, and the transmittance was measured. Irradiating ArF excimer laser using the same sample,
The change in transmittance and the change in refractive index at that time were measured. Table 1 shows the results.

【００１５】実施例３ 高純度のテトラメトキシシランをアルゴンガスに同伴さ
せて酸水素火炎中に導入し火炎加水分解して得られたす
す状シリカを回転する基体上に堆積させて、スート体を
得た。得られたスート体の平均的な嵩密度は１．３ｇ／
ｃｍ３であった。このスート体を酸素８０ｖｏｌ％、Ｈ
ｅ２０ｖｏｌ％の酸化性雰囲気内で９００℃で２０時間
仮焼結した。前記仮焼結でスート体の嵩密度は１．５ｇ
／ｃｍ３に増大し、また全体の密度分布ば低減した。次
いでＨｅ１００ｖｏｌ％の雰囲気て炉内温度を１４５０
℃に昇温し、スート体を引上げながら透明ガラス化し
た。得られた石英ガラス体のＯＨ濃度は２５ｐｐｍで、
水素は検出されなかった。この石英ガラス体を実施例１
と同様の方法で同様な大きさに成型し、成型体の周囲の
グラファイトとの接触部分をＨＦエッチング処理で十分
に除去し、次いで高圧水素処理炉中で水素５気圧、１０
００℃で３２時間加熱して水素ローディングを実施し
た。該処理に引き続いて成型体のアニール処理を行っ
た。前記アニール処理は大気雰囲気で１１５０℃に２０
時間保持し、次いで６００℃まで５℃／ｍｉｎの降温速
度で徐冷したのち自然冷却して除歪操作を行った。得ら
れた成型体の屈折率分布（Δｎ）は１×１０−６、複屈
折率は１ｎｍ／ｃｍ以下で、３方向脈理や層状構造がみ
れなかった。またＯＨ基濃度は８０ｐｐｍ、水素分子濃
度は１．０×１０１８分子／ｃｍ３であった。前記成型
体から直径６０ｍｍ、高さ１０ｍｍの試料を切り出し、
透過率を測定した。また同じ試料を用いてＡｒＦエキシ
マレーザーを照射し、その時の透過率変化及び屈折率変
化を測定した。その結果を表１に示す。Example 3 Soot-like silica obtained by introducing high-purity tetramethoxysilane into an oxyhydrogen flame with argon gas and subjecting it to flame hydrolysis is deposited on a rotating substrate to form a soot body. Obtained. The average bulk density of the obtained soot body was 1.3 g /
cm 3 . 80% by volume of oxygen, H
e Temporarily sintered at 900 ° C. for 20 hours in an oxidizing atmosphere of 20 vol%. The bulk density of the soot body by the above-mentioned preliminary sintering is 1.5 g
/ Cm 3 , and overall density distribution decreased. Then, the furnace temperature was set to 1450 in an atmosphere of 100 vol% He.
The temperature was raised to ° C., and the soot body was pulled up and vitrified transparently. The OH concentration of the obtained quartz glass body was 25 ppm,
No hydrogen was detected. Example 1
Then, the portion in contact with graphite around the molded body is sufficiently removed by an HF etching process, and then, in a high-pressure hydrogen processing furnace, 5 atm of hydrogen and 10 atm.
Hydrogen loading was performed by heating at 00 ° C. for 32 hours. Subsequent to the treatment, the molded body was subjected to an annealing treatment. The annealing treatment is performed at 1150 ° C. in an air atmosphere for 20 minutes.
After holding for a time, and then gradually cooling to a temperature of 600 ° C. at a temperature lowering rate of 5 ° C./min, natural cooling was performed to perform a strain removing operation. The obtained molded article had a refractive index distribution (Δn) of 1 × 10 −6 , a birefringence of 1 nm / cm or less, and no three-way striae or a layered structure was observed. The OH group concentration was 80 ppm, and the hydrogen molecule concentration was 1.0 × 10 18 molecules / cm 3 . Cut out a sample having a diameter of 60 mm and a height of 10 mm from the molded body,
The transmittance was measured. Further, the same sample was irradiated with an ArF excimer laser, and a change in transmittance and a change in refractive index at that time were measured. Table 1 shows the results.

【００１６】[0016]

【表１】 [Table 1]

【００１７】上記表１にみるように本発明の製造方法で
得られた石英ガラスは、ＡｒＦエキシマレーザー光の長
時間の照射によっても殆ど透過率の低下がない上に、コ
ンパクションもみれない。前記コンパクションは、レー
ザー照射に伴う石英ガラスの収縮のことをいう。このコ
ンパクションが起こると屈折率が上昇し、露光装置のレ
ンズ等の光学系の結像特性の悪化が起こる。As shown in Table 1, the quartz glass obtained by the manufacturing method of the present invention has almost no decrease in transmittance even after prolonged irradiation with ArF excimer laser light, and shows no compaction. The compaction refers to shrinkage of quartz glass due to laser irradiation. When this compaction occurs, the refractive index increases, and the imaging characteristics of an optical system such as a lens of the exposure apparatus deteriorate.

【００１８】[0018]

【発明の効果】本発明の製造方法では、エキシマレーザ
ーに対しても高い透過率を有し、かつ耐レーザー性に優
れた光学用石英ガラスを製造できる。特に大口径、肉厚
なＡｒＦエキシマレーザー用光学石英ガラスの製造にお
いて有効で、長時間のＡｒＦエキシマレーザー光の照射
に対しても透過率の低下がなく、かつ安定である。According to the production method of the present invention, it is possible to produce a quartz glass for optics having a high transmittance to an excimer laser and excellent laser resistance. In particular, it is effective in manufacturing a large-diameter and thick optical quartz glass for an ArF excimer laser, and is stable without a decrease in transmittance even for a long irradiation of ArF excimer laser light.

─────────────────────────────────────────────────────
────────────────────────────────────────────────── ───

【手続補正書】[Procedure amendment]

【提出日】平成１１年２月４日（１９９９．２．４）[Submission date] February 4, 1999 (1999.2.4)

【手続補正１】[Procedure amendment 1]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】００１３[Correction target item name] 0013

【補正方法】変更[Correction method] Change

【補正内容】[Correction contents]

【００１３】上記成型体の周囲のグラファイトとの接触
部分を十分にＨＦエッチング処理で除去し、次いで高圧
水素処理炉中で水素１０気圧、１１００℃で２４時間加
熱して水素ローディングを実施した。該処理に引き続い
て成型体のアニール処理を行った。前記アニール処理で
は水素１気圧の雰囲気中で１１５０℃に２０時間保持
し、次いで６００℃まで５℃／時間の降温速度で徐冷し
たのち自然冷却して除歪操作を行った。得られた成型体
の屈折率分布（Δｎ）は１×１０ー6、複屈折率は１ｎｍ
／ｃｍ以下で、３方向脈理や層状構造がみれなかった。
またＯＨ基濃度は６５ｐｐｍ、水素分子濃度は２．５×
１０18分子／ｃｍ3であった。前記成型体から直径６０
ｍｍ、高さ１０ｍｍの試料を切り出し、透過率を測定し
た。また同じ試料を用いてＡｒＦエキシマレーザーをパ
ルス当りのエネルギ−密度２０ｍＪ／ｃｍ2、２００Ｈ
ｚで照射し、その時の透過率変化及び屈折率変化を測定
した。その結果を表１に示す。A portion of the molded body which was in contact with graphite around the graphite was sufficiently removed by HF etching, and then heated in a high-pressure hydrogen treatment furnace at 10 atm of hydrogen and at 1100 ° C. for 24 hours to carry out hydrogen loading. Subsequent to the treatment, the molded body was subjected to an annealing treatment. The annealing treatment is held for 20 hours in 1150 ° C. in an atmosphere of 1 atm hydrogen and then 600 ° C. to 5 ° C. / After slowly cooling time cooling rate was naturally cooled was remove strains operation. The obtained molded product has a refractive index distribution (Δn) of 1 × 10 −6 and a birefringence of 1 nm.
/ Cm or less, three-way striae and a layered structure were not observed.
The OH group concentration is 65 ppm, and the hydrogen molecule concentration is 2.5 ×
It was 10 18 molecules / cm 3 . From the molded body, diameter 60
A sample having a height of 10 mm and a height of 10 mm was cut out, and the transmittance was measured. The path of the ArF excimer laser using the same sample
Energy density per lux 20 mJ / cm 2 , 200H
Irradiation was performed at z, and the change in transmittance and the change in refractive index at that time were measured. Table 1 shows the results.

【手続補正２】[Procedure amendment 2]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】００１４[Correction target item name] 0014

【補正方法】変更[Correction method] Change

【補正内容】[Correction contents]

【００１４】実施例２ 高純度のメチルトリメトキシシ
ランをアルゴンガスに同伴させて酸水素火炎中に導入し
火炎加水分解して得られたすす状シリカを回転する基体
上に堆積させて、スート体を得た。得られたスート体の
平均的な嵩密度は１．３ｇ／ｃｍ3であった。このスー
ト体を酸素８０ｖｏｌ％、Ｈｅ２０ｖｏｌ％の酸化性雰
囲気内で９００℃で１０時間加熱して仮焼結した。前記
仮焼結でスート体の嵩密度は１．５ｇ／ｃｍ3に増大
し、また全体の密度分布ば低減した。次いで酸素５０ｖ
ｏｌ％、Ｈｅ５０ｖｏｌ％の酸化性雰囲気て炉内温度を
１４５０℃に昇温し、スート体を引上げながら透明ガラ
ス化した。得られた石英ガラス体のＯＨ濃度は３０ｐｐ
ｍで、水素は検出されなかった。この石英ガラス体を実
施例１と同様の方法で同様な大きさに成型し、成型体の
周囲のグラファイトとの接触部分をＨＦエッチング処理
で十分に除去し、次いで高圧水素処理炉中で水素５気
圧、１０００℃で３２時間加熱して水素ローディングを
施した。該処理に引き続いて成型体のアニール処理を行
った。前記アニール処理は大気雰囲気で１１５０℃に２
０時間保持した。次いで６００℃まで５℃／時間の降温
速度で徐冷したのち自然冷却して除歪操作を行った。得
られた成型体の屈折率分布（Δｎ）は１×１０ー6、複屈
折率は１ｎｍ／ｃｍ以下で、３方向脈理や層状構造がみ
れなかった。またＯＨ基濃度は８０ｐｐｍ、水素分子濃
度は１．０×１０18分子／ｃｍ3であった。前記成型体
から直径６０ｍｍ、高さ１０ｍｍの試料を切り出し、透
過率を測定した。また同じ試料を用いてＡｒＦエキシマ
レーザーを照射し、その時の透過率変化及び屈折率変化
を測定した。その結果を表１に示す。Example 2 A soot-like silica obtained by introducing high-purity methyltrimethoxysilane into an oxyhydrogen flame with argon gas and subjecting it to flame hydrolysis was deposited on a rotating substrate. I got The average bulk density of the obtained soot body was 1.3 g / cm 3 . The soot body was preliminarily sintered by heating at 900 ° C. for 10 hours in an oxidizing atmosphere of 80 vol% oxygen and 20 vol% He. The bulk density of the soot body was increased to 1.5 g / cm 3 by the preliminary sintering, and the overall density distribution was reduced. Then oxygen 50v
The temperature in the furnace was raised to 1450 ° C. in an oxidizing atmosphere of 50% by volume and He / vol. The OH concentration of the obtained quartz glass body is 30 pp
At m, no hydrogen was detected. This quartz glass body was molded to the same size by the same method as in Example 1, and the portion in contact with graphite around the molded body was sufficiently removed by HF etching. Heating was carried out at 1000 ° C. for 32 hours under atmospheric pressure to carry out hydrogen loading. Subsequent to the treatment, the molded body was subjected to an annealing treatment. The annealing treatment is performed at 1150 ° C.
Hold for 0 hours. Then After gradually cooled at a cooling rate of 5 ° C. / time to 600 ° C. was naturally cooled was remove strains operation. The obtained molded product had a refractive index distribution (Δn) of 1 × 10 −6 , a birefringence of 1 nm / cm or less, and no three-way striae or a layered structure was observed. The OH group concentration was 80 ppm, and the hydrogen molecule concentration was 1.0 × 10 18 molecules / cm 3 . A sample having a diameter of 60 mm and a height of 10 mm was cut out from the molded body, and the transmittance was measured. Further, the same sample was irradiated with an ArF excimer laser, and a change in transmittance and a change in refractive index at that time were measured. Table 1 shows the results.

【手続補正３】[Procedure amendment 3]

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】００１５[Correction target item name] 0015

【補正方法】変更[Correction method] Change

【補正内容】[Correction contents]

【００１５】実施例３ 高純度のテトラメトキシシラン
をアルゴンガスに同伴させて酸水素火炎中に導入し火炎
加水分解して得られたすす状シリカを回転する基体上に
堆積させて、スート体を得た。得られたスート体の平均
的な嵩密度は１．３ｇ／ｃｍ 3であった。このスート体
を酸素８０ｖｏｌ％、Ｈｅ２０ｖｏｌ％の酸化性雰囲気
内で９００℃で２０時間仮焼結した。前記仮焼結でスー
ト体の嵩密度は１．５ｇ／ｃｍ3に増大し、また全体の
密度分布ば低減した。次いでＨｅ１００ｖｏｌ％の雰囲
気て炉内温度を１４５０℃に昇温し、スート体を引上げ
ながら透明ガラス化した。得られた石英ガラス体のＯＨ
濃度は２５ｐｐｍで、水素は検出されなかった。この石
英ガラス体を実施例１と同様の方法で同様な大きさに成
型し、成型体の周囲のグラファイトとの接触部分をＨＦ
エッチング処理で十分に除去し、次いで高圧水素処理炉
中で水素５気圧、１０００℃で３２時間加熱して水素ロ
ーディングを実施した。該処理に引き続いて成型体のア
ニール処理を行った。前記アニール処理は大気雰囲気で
１１５０℃に２０時間保持し、次いで６００℃まで５℃
／時間の降温速度で徐冷したのち自然冷却して除歪操作
を行った。得られた成型体の屈折率分布（Δｎ）は１×
１０ー6、複屈折率は１ｎｍ／ｃｍ以下で、３方向脈理や
層状構造がみれなかった。またＯＨ基濃度は８０ｐｐ
ｍ、水素分子濃度は１．０×１０18分子／ｃｍ3であっ
た。前記成型体から直径６０ｍｍ、高さ１０ｍｍの試料
を切り出し、透過率を測定した。また同じ試料を用いて
ＡｒＦエキシマレーザーを照射し、その時の透過率変化
及び屈折率変化を測定した。その結果を表１に示す。Example 3 High Purity Tetramethoxysilane
Is introduced into an oxyhydrogen flame with argon gas
Soot-like silica obtained by hydrolysis is coated on a rotating substrate.
It was deposited to obtain a soot body. Average of soot body obtained
Typical bulk density is 1.3 g / cm ThreeMet. This soot body
Oxidizing atmosphere of oxygen 80vol% and He20vol%
Sintering at 900 ° C. for 20 hours. Sue in the pre-sintering
The bulk density of the body is 1.5 g / cmThreeTo increase the overall
The density distribution was reduced. Next, an atmosphere of 100 vol% He
The furnace temperature was raised to 1450 ° C and the soot body was pulled up.
While the glass was transparent. OH of the obtained quartz glass body
The concentration was 25 ppm and no hydrogen was detected. This stone
An English glass body was formed to a similar size in the same manner as in Example 1.
Mold and contact the graphite with the surrounding graphite
Removed sufficiently by etching, then high-pressure hydrogen treatment furnace
In a hydrogen atmosphere, heat at 1000 ° C for 32 hours at 5 atm of hydrogen.
Was implemented. Following the treatment,
Neil treatment was performed. The annealing treatment is performed in an air atmosphere.
Hold at 1150 ° C for 20 hours, then 5 ° C to 600 ° C
/timeSlow cooling at the rate of temperature decrease, then natural cooling to remove strain
Was done. The refractive index distribution (Δn) of the obtained molded product is 1 ×
10-6, The birefringence is 1 nm / cm or less,
No layered structure was seen. The OH group concentration is 80 pp
m, hydrogen molecule concentration is 1.0 × 1018Molecule / cmThreeSo
Was. A sample having a diameter of 60 mm and a height of 10 mm from the molded body
Was cut out and the transmittance was measured. Also, using the same sample
Irradiation with ArF excimer laser, change in transmittance at that time
And the change in refractive index. Table 1 shows the results.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 西村 裕幸 福島県郡山市田村町金屋字川久保88番地 信越石英株式会社石英技術研究所内 Ｆターム(参考） 4G014 AH15 AH21  ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Nishimura 88 Kanagawa, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Shin-Etsu Quartz Co., Ltd. Quartz Research Laboratory F-term (reference) 4G014 AH15 AH21

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】高純度の揮発性珪素化合物を火炎加水分解
して生成するすす状シリカを基体上に堆積させて多孔質
シリカ母材を形成する工程、該多孔質シリカ母材を酸化
性雰囲気中で加熱し透明ガラス化し石英ガラス体を得る
工程、及び還元性雰囲気中で熱処理する工程を含むこと
を特徴とするエキシマレーザー用光学石英ガラスの製造
方法。1. A step of depositing soot-like silica produced by flame hydrolysis of a high-purity volatile silicon compound on a substrate to form a porous silica matrix, and forming the porous silica matrix in an oxidizing atmosphere. A method for producing an optical quartz glass for excimer laser, comprising: a step of heating the glass in a transparent glass to obtain a quartz glass body; and a step of performing a heat treatment in a reducing atmosphere. 【請求項２】酸化性雰囲気中での加熱温度が１４００℃
〜１６００℃であることを特徴とする請求項１に記載の
エキシマレーザー用光学石英ガラスの製造方法。2. A heating temperature in an oxidizing atmosphere of 1400 ° C.
The method for producing optical quartz glass for an excimer laser according to claim 1, wherein the temperature is from -1600 ° C. 【請求項３】石英ガラス体を得る工程において、多孔質
シリカ母材を酸化性雰囲気中で８００〜１４００℃で加
熱し緻密化したのち、不活性ガス雰囲気中で１４００℃
〜１６００℃で加熱することを特徴とする請求項１に記
載のエキシマレーザー用光学石英ガラスの製造方法。3. In the step of obtaining a quartz glass body, the porous silica base material is heated and densified at 800 to 1400 ° C. in an oxidizing atmosphere, and then heated to 1400 ° C. in an inert gas atmosphere.
The method for producing an optical quartz glass for an excimer laser according to claim 1, wherein the heating is performed at a temperature of from about 1600 ° C to about 1600 ° C. 【請求項４】酸化性雰囲気中の酸素濃度を３０ｖｏｌ％
以上１００ｖｏｌ％未満とすることを特徴とする請求項
１ないし３のいずれか１に記載のエキシマレーザー用光
学石英ガラスの製造方法。4. An oxygen concentration in an oxidizing atmosphere of 30 vol%
The method for producing an optical quartz glass for an excimer laser according to any one of claims 1 to 3, wherein the content is at least 100 vol%. 【請求項５】透明ガラス化した石英ガラス体を成型した
のち還元性雰囲気中で熱処理することを特徴とする請求
項１ないし４のいずれか１に記載のエキシマレーザー用
光学石英ガラスの製造方法。5. The method for producing an optical quartz glass for an excimer laser according to claim 1, wherein the transparent vitrified quartz glass body is molded and then heat-treated in a reducing atmosphere. 【請求項６】還元性雰囲気中での熱処理を温度６００〜
１２００℃、圧力１気圧以上で行うことを特徴とする請
求項５に記載のエキシマレーザー用光学石英ガラスの製
造方法。6. A heat treatment in a reducing atmosphere at a temperature of 600-600.
The method for producing an optical quartz glass for an excimer laser according to claim 5, wherein the method is performed at 1200 ° C. and a pressure of 1 atm or more. 【請求項７】還元性雰囲気中での熱処理で１×１０１７
分子／ｃｍ３以上の水素分子をドープすることを特徴と
する請求項１ないし６のいずれか１に記載のエキシマレ
ーザー用光学石英ガラスの製造方法。7. A heat treatment in a reducing atmosphere is performed at a concentration of 1 × 10 17
Method for producing an optical quartz glass for excimer laser according to any one of claims 1 to 6, characterized in that doping molecules / cm 3 or more hydrogen molecules. 【請求項８】還元性雰囲気中での熱処理後、大気中で１
１００〜１２００℃の温度に保持しアニール処理を行
い、次いで５０℃／時間以下の徐令速度で徐冷すること
を特徴とする請求項１ないし７のいずれか１に記載のエ
キシマレーザー用光学石英ガラスの製造方法。8. After the heat treatment in a reducing atmosphere, 1 hour in the air.
The optical quartz for an excimer laser according to any one of claims 1 to 7, wherein the annealing is performed while maintaining the temperature at 100 to 1200 ° C, and then gradually cooled at a gradually increasing rate of 50 ° C / hour or less. Glass manufacturing method.
JP37108498A 1998-12-25 1998-12-25 Manufacturing method of optical quartz glass for excimer laser Expired - Fee Related JP4011217B2 (en)

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US7784307B2 (en) 2004-04-28 2010-08-31 Asahi Glass Company, Limited Optical member made of synthetic quartz glass, and process for its production
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JP2007084427A (en) * 2005-09-16 2007-04-05 Corning Inc Fused silica glass and method for making the same
JP2013006722A (en) * 2011-06-23 2013-01-10 Sumitomo Electric Ind Ltd Method for producing base material for synthetic quartz glass and base material for synthetic quartz glass
US9769913B2 (en) 2013-02-01 2017-09-19 Inter-University Research Institute Corporation High Energy Accelerator Research Organization Burst-laser generator using an optical resonator

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