JP3336761B2 - Method for producing synthetic quartz glass for light transmission - Google Patents
Method for producing synthetic quartz glass for light transmissionInfo
- Publication number
- JP3336761B2 JP3336761B2 JP21623394A JP21623394A JP3336761B2 JP 3336761 B2 JP3336761 B2 JP 3336761B2 JP 21623394 A JP21623394 A JP 21623394A JP 21623394 A JP21623394 A JP 21623394A JP 3336761 B2 JP3336761 B2 JP 3336761B2
- Authority
- JP
- Japan
- Prior art keywords
- quartz glass
- concentration
- oxygen
- light
- synthetic quartz
- 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
Links
Classifications
-
- 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
- C03B2201/02—Pure silica glass, e.g. pure fused quartz
- C03B2201/03—Impurity concentration specified
-
- 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
-
- 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
- C03C2201/08—Doped silica-based glasses containing boron or halide
- C03C2201/11—Doped silica-based glasses containing boron or halide containing chlorine
-
- 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
- C03C2203/40—Gas-phase processes
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Thermal Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Glass Melting And Manufacturing (AREA)
- Glass Compositions (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は光透過用合成石英ガラス
の製造方法に関し、より詳細には、エキシマレーザー
(Xe−Cl:308nm 、Kr−F :248nm、Ar−F :193nm) 、低
圧水銀ランプ(185nm) 、エキシマランプ (Xe−Xe:172n
m)などの真空紫外光〜紫外光用のレンズやプリズム、窓
材等の光学部品として用いられる光透過用合成石英ガラ
スの製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic quartz glass for light transmission.
Relates manufacturing method, and more particularly, an excimer laser (Xe-Cl: 308nm, Kr -F: 248nm, Ar-F: 193nm), a low pressure mercury lamp (185 nm), an excimer lamp (Xe-Xe: 172n
m) vacuum ultraviolet light - ultraviolet lenses and prisms for light, such as, regarding manufacturing methods of the light-transmitting synthetic quartz glass used as an optical component of a window material or the like.
【0002】[0002]
【従来の技術】合成石英ガラスは約150nm〜約5μ
mという広い波長範囲で光を透過するため応用範囲が広
いこと、熱膨張係数が小さいために光軸のずれが小さく
高精度の光学系を構成できること、耐熱性が高いために
広い温度範囲で使用できること、高純度な二酸化ケイ素
であるために高エネルギーの光を照射しても損傷を受け
にくいこと等、数々の点で非常に優れたガラス材料であ
る。このような優れた特性を生かした用途の一つとし
て、LSI等の集積回路パターンを露光描画するリソグ
ラフィ装置の光学材料用がある。従来、このリソグラフ
ィ装置の露光光源としては、Hg輝線スペクトルのg線
(435.8nm)やi線(365nm)が用いられ、
その光学ガラス材料として多成分からなる光学ガラスが
用いられていた。しかし、最近回路の集積度をさらに向
上させるために露光に用いる光の波長を短くする傾向に
あり、この場合には真空紫外域〜紫外域での光吸収の少
ない合成石英ガラスを照明光学系及び露光光学系に用い
る必要が生じる。また、低圧水銀ランプ(185nm)
やエキシマランプ(Xe−Xe:172nm)は光CV
Dやシリコンウエハーのアッシング、エッチング、オゾ
ン発生装置に用いられたり、あるいは今後前記用途に適
用すべく開発が進められているが、これらランプのガス
封入管及びこれらの波長の光学素子にも前記合成石英ガ
ラスを用いる必要が生じる。2. Description of the Related Art Synthetic quartz glass has a thickness of about 150 nm to about 5 μm.
It has a wide range of applications because it transmits light over a wide wavelength range of m. It has a small thermal expansion coefficient, so it can be used to construct a high-precision optical system with a small deviation of the optical axis. It is a glass material that is very excellent in various points, such as being able to be used and being hardly damaged even when irradiated with high energy light because of high purity silicon dioxide. One of the applications utilizing such excellent characteristics is as an optical material of a lithography apparatus for exposing and drawing an integrated circuit pattern such as an LSI. Conventionally, g-line (435.8 nm) or i-line (365 nm) of the Hg emission line spectrum has been used as an exposure light source of this lithography apparatus.
Optical glass composed of multiple components has been used as the optical glass material. However, recently there has been a trend to shorten the wavelength of light used for exposure in order to further improve the degree of circuit integration, in which case synthetic silica glass with low light absorption in the vacuum ultraviolet to ultraviolet regions is used for illumination optical systems and It becomes necessary to use it for an exposure optical system. In addition, a low-pressure mercury lamp (185 nm)
And excimer lamps (Xe-Xe: 172 nm) use light CV
It is used for ashing, etching, and ozone generators of D and silicon wafers, or is being developed to be applied to the above-mentioned applications in the future. It becomes necessary to use quartz glass.
【0003】これらの光学系に用いられる石英ガラス材
料は、使用波長での耐光性が高いこと(光照射後に透過
率が低下しにくいこと)が要求されるとともに、レンズ
やプリズムとして使用されるものにおいては、前記特性
に加えてさらに屈折率の均質性も要求される。前記耐光
性に関しては、使用する光の波長領域で光吸収が事実上
検出されず蛍光も検出されず、長時間の光照射を行った
後にも光吸収帯が誘起されないことが要求され、KrF
エキシマレーザー(248nm)を使用する場合は、最
も厳しい条件として400mJ/cm2 、100Hzの
条件で106 ショットの照射を行った後の248nmに
おける透過率の低下が0.1%以下であることが要求さ
れる。さらに、より短波長の光に対し、より高密度な照
射条件でもさらに長時間の照射に耐える材料の開発が望
まれている。[0003] The quartz glass material used for these optical systems is required to have high light resistance at the used wavelength (the transmittance is hardly reduced after light irradiation) and to be used as a lens or a prism. In addition, in addition to the above properties, homogeneity of the refractive index is also required. With respect to the light resistance, it is required that light absorption is practically not detected and fluorescence is not detected in a wavelength region of light to be used, and that a light absorption band is not induced even after long-time light irradiation.
When using an excimer laser (248nm) is that lowering of the transmittance at 248nm after the irradiation of 10 6 shots 400 mJ / cm 2, 100 Hz conditions as the most severe condition is not more than 0.1% Required. Further, it is desired to develop a material that can withstand shorter-wavelength light even under a higher-density irradiation condition for a longer time.
【0004】通常、このような厳しい条件に適合可能な
石英ガラスとして、合成石英ガラスが挙げられる。一般
的に合成石英ガラスという呼び名は、出発原料として天
然のSiO2 を用いない全ての石英ガラスに用いられる
が、この合成石英ガラスを製造する方法としては、種々
の方法が存在する。従って、原料の純度や製造方法に起
因して、製造された合成石英ガラスの不純物元素濃度
(金属元素濃度、非金属元素濃度)や欠陥濃度なども様
々なグレードのものが存在し、すべての合成石英ガラス
が理想的な透過光学系用のガラス材料となり得るわけで
はない。[0004] Usually, synthetic quartz glass can be cited as a quartz glass which can meet such severe conditions. Generally, the name of synthetic quartz glass is used for all quartz glasses that do not use natural SiO 2 as a starting material, and there are various methods for producing this synthetic quartz glass. Therefore, depending on the purity of the raw material and the manufacturing method, there are various grades of impurity element concentration (metal element concentration, non-metal element concentration), defect concentration, etc. of the manufactured synthetic quartz glass. Quartz glass cannot be the ideal glass material for transmission optics.
【0005】合成石英ガラスの製造法には大別して気相
法と液相法があり、光学的な用途に用いられる材料の製
造方法としては気相法が主流であるが、この気相法にも
直接合成法、プラズマCVD法、スート法等があり、原
料や製造方法に起因して石英ガラス中における金属等の
不純物、OH基、Cl、H2 、O2 、酸素過剰欠陥、酸
素欠乏欠陥、環構造欠陥等の濃度が異なる。これらの不
純物や欠陥等の濃度は、合成石英ガラスの光吸収・蛍光
・屈折率等の光学特性に大きな影響を及ぼし、従って上
記した高エネルギー光での照射に対する耐光性(照射後
の透過率低下の程度)にも大きな影響を及ぼすことが知
られている。そこで、従来より前記不純物や欠陥等と耐
光性との関係について、種々の検討がなされている。[0005] Synthetic quartz glass production methods are roughly classified into a gas phase method and a liquid phase method. The gas phase method is mainly used as a method for producing materials used for optical applications. There are also direct synthesis methods, plasma CVD methods, soot methods, etc., and impurities such as metals, OH groups, Cl, H 2 , O 2 , oxygen excess defects and oxygen deficiency defects in quartz glass due to raw materials and manufacturing methods. , Ring structure defects and the like. The concentration of these impurities and defects has a great effect on the optical properties of the synthetic quartz glass, such as light absorption, fluorescence, and refractive index. Therefore, the light resistance against the irradiation with high-energy light (lower transmittance after irradiation) Is also known to have a significant effect. Therefore, various studies have conventionally been made on the relationship between the impurities and defects and the light resistance.
【0006】[0006]
【発明が解決しようとする課題】これらの検討において
は、石英ガラスの耐光性を向上させるために、例えば石
英ガラス中のOH基の濃度を高くすること、H2 含有量
を少なくすること、H2含有量を多くすること、酸素欠
陥(過剰欠陥及び欠乏欠陥)をなくすこと、Heなどの
不活性ガス分子を溶存させることなど、種々の方法が提
案されている。In these studies, in order to improve the light resistance of quartz glass, for example, increasing the concentration of OH groups in quartz glass, reducing the H 2 content, possible to increase the 2 content, eliminating the oxygen defects (excessive defects and deficient defects), etc. be dissolved inert gas molecules, such as He, various methods have been proposed.
【0007】しかし、前記した提案の内容からもわかる
ように、相互に矛盾する提案が存在し、真空紫外域〜紫
外域の光の照射に対する石英ガラスの光損傷を抑制し、
あるいは防止するために合成石英ガラスが具備すべき条
件は、未だに完全に把握されていないという課題があっ
た。However, as can be seen from the contents of the above proposals, there are mutually contradictory proposals, which suppress the optical damage of quartz glass to irradiation of light in the vacuum ultraviolet region to the ultraviolet region,
Alternatively, there has been a problem that the conditions to be provided for the synthetic quartz glass in order to prevent it have not yet been completely grasped.
【0008】例えば、特開平2−69332号公報に記
載されている「レーザー光用透過体」の発明において
は、石英ガラス中のOH基濃度が増加するとともに、吸
蔵されるH2 の量が増加し、レーザ光に対する耐光性が
低下するという記載がなされている。[0008] For example, in the invention of are described in JP-A-2-69332 "laser-light transmissive member", the OH group concentration in the quartz glass increases, the amount of H 2 being occluded increase However, it is described that the light resistance to laser light is reduced.
【0009】また、特開平3−101282号公報に記
載されている「レーザー光用光学系部材」の発明におい
ては、石英ガラス中に含有されるH2 ガス分子がレーザ
光に対する耐光性を向上させるという記載がなされてお
り、前記公報の記載の内容と全く反対の提案となってい
る。In the invention of the "optical member for laser light" described in JP-A-3-101282, H 2 gas molecules contained in quartz glass improve the light resistance to laser light. The proposal is completely opposite to the contents described in the above publication.
【0010】そこで本発明者らは、高エネルギー密度を
有する真空紫外域〜紫外域のレーザ光が長時間照射され
た場合にもほとんど透過率が低下しない光透過用合成石
英ガラス及びその製造方法を提供することを目的とし
て、合成石英ガラス中の不純物や欠陥と前記合成石英ガ
ラスに紫外線が照射された際の透過率の変化等について
検討したところ、合成石英ガラスに高エネルギー密度の
172nm、185nm、193nm、又は248nm
のレーザ光を照射した時に生ずる透過率低下の原因が、
図1のグラフに示した約260nm(4.7eV)を中
心とした吸収を有する≡Si−0°(非結合酸素)欠陥
及び約210nm(5.9eV)を中心とした吸収を有
する≡Si・(E’中心)欠陥の生成に起因することを
確認した。なお、前記の「≡Si」という記号は三重結
合を意味するのではなくシリコン原子が3個の酸素原子
と単結合を形成している状態を模式的に表したものであ
る。Therefore, the present inventors have developed a synthetic quartz glass for light transmission and a method of manufacturing the same, wherein the transmittance is hardly reduced even when a laser beam in the vacuum ultraviolet region to the ultraviolet region having a high energy density is irradiated for a long time. For the purpose of providing, a study was made of impurities and defects in the synthetic quartz glass and a change in transmittance when the synthetic quartz glass was irradiated with ultraviolet rays, and the like. Synthetic quartz glass had a high energy density of 172 nm, 185 nm, 193 nm or 248 nm
The cause of the transmittance decrease that occurs when irradiating the laser light of
The Si—0 ° (non-bonded oxygen) defect with an absorption centered at about 260 nm (4.7 eV) and the SiSi with an absorption centered at about 210 nm (5.9 eV) shown in the graph of FIG. (E 'center) It was confirmed that the defect was caused by generation of defects. Note that the symbol “≡Si” does not mean a triple bond, but schematically represents a state in which a silicon atom forms a single bond with three oxygen atoms.
【0011】そこで次に、これらの欠陥の生成が合成石
英ガラス中のOH基濃度、H2 濃度、欠陥濃度等のう
ち、どれによって左右されるのかを検討し、10〜80
0ppmのOH基を有する合成石英ガラスにレーザー光
を照射し、前記OH基は両欠陥の生成に無関係であるこ
と、及びH2 濃度が1015〜1018個/cm3 の合成石
英ガラスにレーザーを照射し、前記H2 は4.7eV
(260nm)を中心とした吸収を有する欠陥の生成を
防止する効果があるものの、5.9eV(210nm)
を中心とした吸収を有する欠陥の生成を抑制又は防止す
る効果はないことを見出した。Then, it is examined which of the OH group concentration, the H 2 concentration, the defect concentration and the like in the synthetic quartz glass affects the generation of these defects.
A synthetic silica glass having 0 ppm OH group is irradiated with a laser beam, and the OH group has no relation to the formation of both defects, and the synthetic quartz glass having an H 2 concentration of 10 15 to 10 18 / cm 3 is irradiated with a laser beam. And H 2 is 4.7 eV
5.9 eV (210 nm), although it has the effect of preventing generation of defects having absorption centered at (260 nm).
It has been found that there is no effect of suppressing or preventing the generation of a defect having an absorption centered on.
【0012】さらに、5.9eVを中心とした吸収を有
する欠陥の生成には、シリル基(SiH)の濃度、酸素
欠乏欠陥の濃度、及びSiCl基の濃度が関係している
ことを見出し、本発明を完成するに至った。Further, they found that the generation of a defect having an absorption centered at 5.9 eV is related to the concentration of a silyl group (SiH), the concentration of an oxygen-deficient defect, and the concentration of a SiCl group. The invention has been completed.
【0013】すなわち、本発明は、高純度ケイ素化合物
から気相化学反応により石英ガラス多孔体を合成し、前
記石英ガラス多孔体を酸素含有雰囲気中で熱処理した後
に真空下で透明ガラス化することにより得られた酸素過
剰型欠陥を含む合成石英ガラスを、水素含有雰囲気下 8
00℃以下で熱処理することを特徴とする溶存水素分子濃
度が1015 個/cm3以上であり、かつSiH 基の濃度、酸素欠
乏欠陥濃度の2倍及びSiCl基の濃度の合計が 5.3×1016
個/cm3以下である光透過用合成石英ガラスの製造方法で
ある。That is, the present invention is to synthesize a porous quartz glass body from a high-purity silicon compound by a gas phase chemical reaction, heat-treat the porous quartz glass body in an oxygen-containing atmosphere, and then form a transparent vitreous glass under vacuum. The obtained synthetic quartz glass containing oxygen-excess type defects is placed under a hydrogen-containing atmosphere.
00 ° C. dissolved hydrogen molecule concentration is 10 15, characterized in that the heat treatment at less / cm 3 or more, and the concentration of SiH groups, oxygen deficient defect concentration twice and concentration total 5.3 × 10 of SiCl groups 16
This is a method for producing a synthetic quartz glass for light transmission, which is not more than individual pieces / cm 3 .
【0014】前記光透過用合成石英ガラス中に、前記し
た不純物以外に金属不純物が含有されていると、真空紫
外光〜紫外光の透過率が低下するために好ましくなく、
アルカリ金属は合計で100ppb以下、アルカリ土類
金属は合計で100ppb以下、遷移金属(Ti、C
r、Fe、Ni、Cu、Ce)は合計で50ppb以下
であるのが好ましい。If the synthetic quartz glass for light transmission contains metal impurities in addition to the above-mentioned impurities, the transmittance from vacuum ultraviolet light to ultraviolet light decreases, which is not preferable.
Alkali metal is 100 ppb or less in total, alkaline earth metal is 100 ppb or less in total, and transition metals (Ti, C
(r, Fe, Ni, Cu, Ce) is preferably 50 ppb or less in total.
【0015】次に、本発明に係る光透過用合成石英ガラ
スの製造方法は、上記した光透過用合成石英ガラスの製
造方法であって、高純度ケイ素化合物から気相化学反応
により石英ガラス多孔体を合成し、前記石英ガラス多孔
体を酸素含有雰囲気中で熱処理した後に真空下で透明ガ
ラス化することにより得られた酸素過剰型欠陥を含む合
成石英ガラスを、水素含有雰囲気下800℃以下で熱処
理することを特徴としている。Next, a method for producing a synthetic quartz glass for light transmission according to the present invention is a method for producing a synthetic quartz glass for light transmission as described above, wherein a quartz glass porous material is produced from a high-purity silicon compound by a gas phase chemical reaction. Synthesized quartz glass containing oxygen-excess type defects obtained by heat-treating the quartz glass porous body in an oxygen-containing atmosphere and then vitrifying it under vacuum at 800 ° C. or lower in a hydrogen-containing atmosphere. It is characterized by doing.
【0016】原料となる高純度ケイ素化合物としては、
例えば四塩化ケイ素やシランが挙げられ、製造された石
英ガラス中における真空紫外光〜紫外光の透過率低下を
防止するため、前記原料中のアルカリ金属は合計で10
0ppb以下、アルカリ土類金属は合計で100ppb
以下、遷移金属(Ti、Cr、Fe、Ni、Cu、C
e)は合計で50ppb以下であるのが好ましい。石英
ガラス多孔体の合成では、特別な条件は必要でなく、通
常の酸水素火炎による加水分解を行えばよいが、加水分
解の際の温度は1000〜2000℃程度が好ましい。The high-purity silicon compound used as a raw material includes
For example, silicon tetrachloride or silane may be mentioned, and in order to prevent a reduction in the transmittance of vacuum ultraviolet light to ultraviolet light in the manufactured quartz glass, the alkali metal in the raw material is 10 in total.
0 ppb or less, total of 100 ppb alkaline earth metals
Hereinafter, transition metals (Ti, Cr, Fe, Ni, Cu, C
e) is preferably not more than 50 ppb in total. In the synthesis of the quartz glass porous body, no special conditions are required, and hydrolysis may be performed by a normal oxyhydrogen flame, but the hydrolysis temperature is preferably about 1000 to 2000 ° C.
【0017】次に、前記工程により得られた石英ガラス
多孔体(スート)を酸素含有雰囲気下で熱処理するが、
酸素分子を多孔体であるスート中にすみやかに拡散させ
て、≡Si−Si≡を≡Si−O−Si≡に変え、かつ
空孔を石英ガラスの内部に形成しないようにするため
に、その温度は1000〜1300℃の範囲が好まし
く、酸素濃度は10〜100vol%以上が好ましい。
前記処理の際の酸素含有量が10vol%未満でその温
度が1000℃未満の場合には、前記した反応が十分に
進行せず、他方その温度が1300℃を超えるとスート
の焼結が多少進行し、後の脱ガス処理が困難となる。Next, the porous quartz glass (soot) obtained in the above step is heat-treated in an oxygen-containing atmosphere.
In order to promptly diffuse oxygen molecules into the soot, which is a porous body, to convert {Si-Si} to {Si-O-Si} and prevent voids from being formed inside the quartz glass, The temperature is preferably in the range of 1000 to 1300 ° C, and the oxygen concentration is preferably 10 to 100 vol% or more.
When the oxygen content at the time of the treatment is less than 10 vol% and the temperature is less than 1000 ° C., the above-mentioned reaction does not sufficiently proceed. On the other hand, when the temperature exceeds 1300 ° C., the soot sintering proceeds somewhat. Then, the subsequent degassing becomes difficult.
【0018】前記工程の後には、上記した酸素ガス処理
により含有される余剰酸素やその他のガス成分をガラス
微粒子中から除去し、後の工程において石英ガラス中へ
のH2 の拡散を容易にするために、脱ガス処理を行うの
が好ましく、この条件としては、真空下あるいは数十P
a以下の減圧下で、水分を含まない(露点が−100℃
以下)不活性ガス雰囲気が好ましい。また、このときの
温度としては、1000〜1400℃が好ましい。脱ガ
ス処理の際の温度が1000℃未満の場合には、酸素等
のガスが十分に除去されず、他方その温度が1400℃
を超えるとガスが十分に除去されないうちに緻密化が始
まってしまう。After the above step, excess oxygen and other gas components contained by the above-described oxygen gas treatment are removed from the glass fine particles to facilitate diffusion of H 2 into quartz glass in a later step. For this reason, it is preferable to perform a degassing treatment.
a under a reduced pressure of not more than water (with a dew point of −100 ° C.)
Hereinafter) an inert gas atmosphere is preferable. The temperature at this time is preferably 1000 to 1400 ° C. If the temperature at the time of the degassing treatment is less than 1000 ° C., gas such as oxygen is not sufficiently removed, while the temperature is 1400 ° C.
If it exceeds 300, densification starts before the gas is not sufficiently removed.
【0019】この後、透明ガラス化を行うが、この場合
の条件は前記脱ガス処理の条件と同様の雰囲気下、14
00〜1600℃の温度範囲で行うのが好ましい。その
温度が1400℃未満では、緻密化が進行しにくく生産
性が悪くなり、他方1600℃を超えると電力の消費に
よりコスト増加となる。Thereafter, transparent vitrification is carried out. In this case, the conditions are as follows:
It is preferable to carry out in a temperature range of 00 to 1600 ° C. If the temperature is lower than 1400 ° C., densification hardly proceeds and productivity is deteriorated. On the other hand, if the temperature exceeds 1600 ° C., cost increases due to power consumption.
【0020】その後の水素含有雰囲気下での熱処理は、
H2 濃度が20vol%以上の還元雰囲気下、800℃
以下で行うのが好ましく、700℃以下がより好まし
い。熱処理の際の水素含有量が20vol%未満では水
素が十分に石英ガラスに吸蔵されず、熱処理の温度が8
00℃を超えると、吸蔵された水素が≡Si−O−Si
≡と反応して≡Si・欠陥の原因となるSiHを生成し
てしまう。The subsequent heat treatment in a hydrogen-containing atmosphere includes
800 ° C. in a reducing atmosphere with an H 2 concentration of 20 vol% or more
It is preferably performed at a temperature of 700 ° C. or less. If the hydrogen content at the time of heat treatment is less than 20 vol%, hydrogen is not sufficiently absorbed by the quartz glass, and the temperature of the heat treatment becomes 8%.
If the temperature exceeds 00 ° C., the absorbed hydrogen becomes ≡Si—O—Si
Reacts with ≡ to generate SiH which causes ≡Si and defects.
【0021】合成石英ガラス中のH2 濃度分布による屈
折率の変動は1×10-6以下であるため、H2 を含有さ
せる工程の前までに屈折率分布が均一化された材料が製
造されていれば、その後のH2 含有雰囲気下での熱処理
により均質性と耐光性とを備えた光透過用合成石英ガラ
スを製造することができる。Since the variation in the refractive index due to the H 2 concentration distribution in the synthetic quartz glass is 1 × 10 −6 or less, a material having a uniform refractive index distribution is manufactured before the step of including H 2. If this is the case, a synthetic quartz glass for light transmission having homogeneity and light resistance can be produced by a subsequent heat treatment in an atmosphere containing H 2 .
【0022】[0022]
【作用】前述したように、種々の製造プロセスで製造し
た合成石英ガラスにKrFエキシマレーザー、ArFエ
キシマレーザー、低圧水銀ランプを照射した後の紫外吸
収スペクトルを検討した結果、これらの光照射による損
傷は、図1に示される2種類の吸収帯、すなわち4.7
eV(260nm)を中心とした吸収を有する酸素過剰
欠陥(以下、260nm帯欠陥と記す)、及び5.9e
V(210nm)を中心とした吸収を有する酸素欠乏欠
陥(以下、210nm帯欠陥と記す)の生成が主な原因
であることを確認した。さらにH2 分子が検出される石
英ガラスでは図2に示すとおり、両者の欠陥のうち26
0nm帯欠陥は検出されないが、210nm帯欠陥は検
出されるもの(実線、破線)と検出されないもの(1点
鎖線)とがあり、H2 分子の存在は耐光性向上に対する
十分条件ではないことが判明した。As described above, as a result of examining the ultraviolet absorption spectrum after irradiating a synthetic quartz glass manufactured by various manufacturing processes with a KrF excimer laser, an ArF excimer laser, and a low-pressure mercury lamp, the damage caused by these light irradiations is considered. , Two types of absorption bands shown in FIG.
an oxygen-excess defect having an absorption centered at eV (260 nm) (hereinafter referred to as 260 nm band defect), and 5.9e
It was confirmed that the generation was mainly caused by oxygen deficiency defects (hereinafter, referred to as 210 nm band defects) having an absorption centered at V (210 nm). Further, in the quartz glass in which H 2 molecules are detected, as shown in FIG.
Although the 0 nm band defect is not detected, the 210 nm band defect is detected (solid line, broken line) and not detected (dashed line), and the presence of H 2 molecule is not a sufficient condition for improving the light resistance. found.
【0023】260nm帯欠陥(≡Si−O°)は、下
記の数1式又は数2式の解離反応により生成すると考え
られる。It is considered that the 260 nm band defect (≡Si-O °) is generated by the dissociation reaction of the following equation (1) or equation (2).
【0024】[0024]
【数1】 (Equation 1)
【0025】[0025]
【数2】 (Equation 2)
【0026】上記反応においては、上記数1式で記載し
た−O−O−結合の方が弱いため、数1式に記載した反
応の方が、比較的弱い光(電磁波)の照射で進行する。In the above reaction, since the -O-O-bond described in the above equation (1) is weaker, the reaction described in the equation (1) proceeds by irradiation of relatively weak light (electromagnetic wave). .
【0027】また、210nm帯欠陥(≡Si・)は、
上記数2式及び下記の数3式〜数5式の解離反応により
生成すると考えられる。Further, the 210 nm band defect (≡Si.)
It is considered to be generated by the dissociation reaction of the above equation (2) and the following equations (3) to (5).
【0028】[0028]
【数3】 (Equation 3)
【0029】[0029]
【数4】 (Equation 4)
【0030】[0030]
【数5】 (Equation 5)
【0031】これらの反応においては、上記数2式より
も上記数3式〜数5式で示した解離反応の方が比較的弱
い光(電磁波)の照射で進行する。もちろん、偏光板検
査で認められるような歪みが存在したり、ラマンスペク
トルで検出される環構造欠陥のように、≡Si−O−S
i≡の結合が歪んだり、応力がかかった状態で保持され
ていれば数2式で示した反応も容易に進行すると考えら
れる。In these reactions, the dissociation reaction shown in the above equations (3) to (5) proceeds with irradiation of relatively weak light (electromagnetic waves) than in the above equation (2). Of course, there is a distortion as observed in the polarizing plate inspection, or as in the case of the ring structure defect detected in the Raman spectrum, ΔSi-OS
If the bond of 反 応 is distorted or held in a stressed state, it is considered that the reaction represented by Formula 2 proceeds easily.
【0032】また、X線、γ線、中性子線イオンビーム
等、紫外線より高エネルギーな電磁波や粒子線を照射し
た際には、数2式で示した反応も容易に進行する。When an electromagnetic wave or a particle beam having a higher energy than ultraviolet rays, such as an X-ray, a γ-ray, a neutron beam ion beam, or the like, is irradiated, the reaction represented by Formula 2 also proceeds easily.
【0033】そこで、本発明者らは2種の欠陥の生成に
関与する合成石英ガラス中のOH基濃度、Cl等の非金
属不純物の濃度、酸素欠陥濃度等との相関を求める検討
を行った。検討した不純物の種類は、OH基、Cl、S
iCl基、H2 、シリル基(≡Si−H)であり、酸素
欠陥の種類は、≡Si−Si≡、及び≡Si−O−O−
Si≡である。ここで、前記OH基の濃度は赤外吸収法
により求めた。また、全Cl濃度は中性子放射化分析法
により求め、Cl2 濃度は昇温脱離ガス分析法より求
め、全Cl濃度とCl2 濃度との差を≡Si−Cl濃度
とした。H2 濃度、≡Si−H濃度はレーザーラマンス
ペクトルのそれぞれ4135cm-1及び2250cm-1
のピークにより検出した強度を、≡Si−O−の結合を
示す800cm-1の散乱ピークの強度で割った値(強度
比)から求めた。≡Si−Si≡欠陥の濃度は真空紫外
域の163nmの吸光度から求めた。≡Si−O−O−
Si≡濃度はレーザー照射後の260nmのピークの吸
光度の大小で判定した。Therefore, the present inventors have studied to obtain correlations with the OH group concentration, the concentration of nonmetallic impurities such as Cl, the concentration of oxygen defects, etc. in the synthetic quartz glass involved in the formation of two kinds of defects. . The types of impurities examined are OH group, Cl, S
iCl group, H 2 , and silyl group (≡Si—H), and the types of oxygen defects are {Si—Si} and {Si—O—O—
Si≡. Here, the concentration of the OH group was determined by an infrared absorption method. The total Cl concentration was determined by neutron activation analysis, the Cl 2 concentration was determined by thermal desorption gas analysis, and the difference between the total Cl concentration and the Cl 2 concentration was defined as the ΔSi—Cl concentration. Concentration of H 2, ≡Si-H concentration each of the laser Raman spectrum 4135 cm -1 and 2250 cm -1
Of the scattering peak at 800 cm −1 indicating the bonding of ≡Si—O— (intensity ratio). The concentration of the {Si—Si} defect was determined from the absorbance at 163 nm in the vacuum ultraviolet region. ≡Si-OO-
The Si≡ concentration was determined by the magnitude of the absorbance of the peak at 260 nm after laser irradiation.
【0034】これらの検討の結果、H2 ガスは酸素過剰
欠陥である≡Si−O−O−Si≡と容易に反応し、下
記の数6式に示した化合物を形成することがわかった。As a result of these studies, it was found that H 2 gas easily reacts with {Si—O—O—Si}, which is an oxygen excess defect, to form a compound represented by the following formula (6).
【0035】[0035]
【数6】 (Equation 6)
【0036】すなわち、上記数6式で示した反応により
H2 は安定なOH基に変化し、上記数1式に示した26
0nm帯欠陥である≡Si−O°は生成しないため、H
2 の有無により図1及び図2に示したような260nm
における吸収の差異が現れると考えられる。従って、石
英ガラス中にH2 が一定量以上存在している合成石英ガ
ラス中には≡Si−O−O−Si≡型の酸素過剰欠陥は
共存しにくいと考えられる。That is, H 2 is converted into a stable OH group by the reaction shown in the above equation (6), and H 2 shown in the above equation (1) is obtained.
Since 0 nm band defect {Si-O °} is not generated, H
260nm as indicated by the presence or absence of 2 in Figures 1 and 2
It is thought that the difference in absorption at Therefore, it is considered that {Si—O—O—Si} type oxygen-excess defects hardly coexist in synthetic quartz glass in which H 2 is present in a certain amount or more in quartz glass.
【0037】以上より260nm帯欠陥の生成を抑制す
るには、石英ガラス中にH2 分子を含有させておく必要
があり、少なくとも前記H2 分子がラマン分光法におい
て検出できる程度に存在していれば、260nm欠陥が
生成されない。ラマン分光法におけるH2 の検出下限は
実質的に1015個/cm3 程度である。また、H2 濃度
が1018個/cm3 以内であれば、H2 の存在による悪
影響は見られない。As described above, in order to suppress the generation of defects at the 260 nm band, it is necessary to contain H 2 molecules in quartz glass, and at least the H 2 molecules are present to such an extent that they can be detected by Raman spectroscopy. In this case, no 260 nm defect is generated. The lower detection limit of H 2 in Raman spectroscopy is substantially about 10 15 / cm 3 . If the H 2 concentration is within 10 18 / cm 3 , there is no adverse effect due to the presence of H 2 .
【0038】次に、酸素欠乏欠陥について検討すると、
酸素欠乏欠陥である≡Si−Si≡に対するH2 の作用
は下記の数7式のようになる。Next, considering the oxygen deficiency defect,
The effect of H 2 on the oxygen deficiency defect {Si—Si} is expressed by the following equation (7).
【0039】[0039]
【数7】 (Equation 7)
【0040】しかし、上記数4式で示したように、一旦
生成した≡Si−Hは余り安定ではなく、再び分解して
210nm帯欠陥である≡Si・を生成する。従って、
石英ガラス中のH2 分子は210nm欠陥の生成を抑制
するには有効でない。However, as shown in the above equation (4), once generated HSi—H is not very stable, and is decomposed again to generate 210Si · which is a 210 nm band defect. Therefore,
H 2 molecules in quartz glass are not effective in suppressing the generation of 210 nm defects.
【0041】図3は、210nm欠陥の各吸光度におけ
る理論的なピーク形状を示したグラフであるが、図3に
示したように、このピークがある程度以上の大きさで検
出されれば、工業的に使用される248nm(5.0e
V)、193nm(6.4eV)、185nm(6.7
eV)の波長域はいずれも吸収ピークの一部となり、透
過率が低下することとなる。図4は210nm欠陥の吸
光度が特定波長域(248nm、193nm、185n
m)での透過率に及ぼす影響を示したグラフである。図
4より、248nmの波長における透過率低下を0.1
%以下に抑えるには、210nm欠陥による吸光度が
0.0039以下である必要があり、193nmの波長
における透過率低下を0.1%以下に抑えるには、21
0nm帯欠陥による吸光度が0.0009以下である必
要があり、185nmの波長における透過率低下を0.
1%以下に抑えるには、210nm帯欠陥による吸光度
が0.0026以下である必要がある。FIG. 3 is a graph showing a theoretical peak shape at each absorbance of a 210 nm defect. As shown in FIG. 248 nm (5.0e
V), 193 nm (6.4 eV), 185 nm (6.7
Each wavelength range of eV) becomes a part of the absorption peak, and the transmittance is reduced. FIG. 4 shows that the absorbance of a 210 nm defect is in a specific wavelength range (248 nm, 193 nm, 185 n).
7 is a graph showing the effect on transmittance in m). FIG. 4 shows that the decrease in transmittance at a wavelength of 248 nm is 0.1%.
%, The absorbance due to a 210 nm defect needs to be 0.0039 or less. To suppress the decrease in transmittance at a wavelength of 193 nm to 0.1% or less, the absorbance is 21% or less.
The absorbance due to a 0 nm band defect needs to be 0.0009 or less, and a decrease in transmittance at a wavelength of 185 nm is reduced by 0.
In order to suppress the density to 1% or less, the absorbance due to a 210 nm band defect needs to be 0.0026 or less.
【0042】従って、≡Si・の吸収断面積を7.37
×10-20 cm2 とすると、前記欠陥の濃度がそれぞれ
5.3×1016個/cm3 以下(248nm)、1.2
×1016個/cm3 以下(193nm)、3.5×10
16個/cm3 以下(185nm)であれば、各波長域で
の透過率の低下が0.1%以下に抑えられることにな
る。以上より、理論的には前記欠陥の濃度が1.2×1
016個/cm3 以下であれば前記した各波長での透過率
の低下がいずれも0.1%以内に抑えられることになる
が、現在の基準では248nmにおける透過率の低下が
0.1%以下に抑えられれば要求基準を満足することに
なる。従って、前記基準に従えば、欠陥の濃度が5.3
×1016個/cm3 以下であればよい。ここで、透過率
の低下の上限値を0.1%以下としているのは、光度計
の精度の限界がこのレベルにあり、これ以下の透過率で
は透過率の低下が実質的に検出されないためであり、≡
Si・の吸収断面積を7.37×10-20 cm2 とした
のは、R.A.Weeks の報告中(J.Appl.Phys.,35(1964)p19
32$ )のγ線を照射した時に生成し易い欠陥≡Si・を
生成させないために必要な≡Si−OH濃度との関係を
示したグラフから求めた。Therefore, the absorption cross section of ≡Si.
Assuming that the density of the defects is 5.3 × 10 16 / cm 3 or less (248 nm) and 1.2 × 10 −20 cm 2 , respectively.
× 10 16 / cm 3 or less (193 nm), 3.5 × 10
If the number is 16 / cm 3 or less (185 nm), the decrease in transmittance in each wavelength region can be suppressed to 0.1% or less. From the above, theoretically, the concentration of the defect is 1.2 × 1
If the number is not more than 0 16 / cm 3 , the decrease in transmittance at each wavelength described above can be suppressed to within 0.1%, but according to the current standard, the decrease in transmittance at 248 nm is 0.1%. %, The required standard is satisfied. Therefore, according to the above criteria, the defect concentration is 5.3.
It should be less than × 10 16 / cm 3 . Here, the reason why the upper limit of the decrease in transmittance is set to 0.1% or less is that the limit of the accuracy of the photometer is at this level, and the decrease in transmittance is not substantially detected at a transmittance lower than this level. And ≡
The reason why the absorption cross section of Si was set to 7.37 × 10 −20 cm 2 was reported by RAWeeks (J. Appl. Phys., 35 (1964) p19).
32 $) was obtained from a graph showing the relationship with the concentration of ≡Si—OH necessary to prevent the generation of a defect ≡Si.
【0043】真空紫外域〜紫外域での光を照射したとき
に欠陥≡Si・を生成しやすい反応は上記数3式〜数5
式に示した反応であるので、この欠陥≡Si・の生産量
を上記した条件以下に制御するには、前記欠陥の生産源
である≡Si−Hの濃度と、≡Si−Si≡の濃度を2
倍した量と、≡Si−Clとの濃度との和が5.3×1
016個/cm3 以下であればよい。これらの結合の濃度
の和が1.2×1016個/cm3 以下であることがより
好ましく、さらに0が理想的であることはいうまでもな
い。前記した推定が正しいことは下記の実施例からも実
証されている。ここで、≡Si−Si≡濃度の2倍とし
たのは、前記結合が切断されると2個の≡Si・が生成
する可能性があるからである。ハロゲン化結合のうち≡
Si−Clだけを挙げたのは、スートの原料としてSi
Cl4 等のシリコン塩化物を用いているためであり、原
料にフッ化物を用いた場合は、≡Si−Fの濃度も大き
くなるので、その濃度が問題となる。The reaction that easily produces a defect ΔSi when irradiated with light in the vacuum ultraviolet region to the ultraviolet region is represented by the above formulas (3) to (5).
Since the reaction is represented by the formula, in order to control the production amount of the defect ≡Si · under the above-mentioned conditions, the concentration of the 生産 Si—H and the concentration of the 2
The sum of the doubled amount and the concentration of ≡Si—Cl is 5.3 × 1
It is sufficient if the number is not more than 0 16 pieces / cm 3 . It is more preferable that the sum of the concentrations of these bonds is 1.2 × 10 16 / cm 3 or less, and it goes without saying that 0 is ideal. The correctness of the above estimation is also demonstrated by the following examples. Here, the concentration of {Si—Si} is set to twice because there is a possibility that two ≡Si · s are generated when the bond is broken. Of the halogenated bonds
Only Si-Cl is cited as the raw material of soot
This is because silicon chloride such as Cl 4 is used. When fluoride is used as a raw material, the concentration of ≡Si—F becomes large, so that the concentration becomes a problem.
【0044】次に、前記光透過用合成石英ガラスの製造
方法における作用について説明する。まず、原料として
高純度ケイ素化合物を用いるのは、原料中の不純物が石
英ガラス中に残存することによる真空紫外光〜紫外光の
透過率低下を防止するためであり、最初に多孔体を合成
するのは、酸素含有雰囲気による処理を行う際に、下記
する酸素雰囲気下での処理を効率よく行うためである。Next, the operation of the method for producing the synthetic quartz glass for light transmission will be described. First, the use of a high-purity silicon compound as a raw material is to prevent a decrease in the transmittance of vacuum ultraviolet light to ultraviolet light due to impurities in the raw material remaining in quartz glass, and first synthesize a porous body. This is because, when performing the treatment in the oxygen-containing atmosphere, the treatment in the oxygen atmosphere described below is efficiently performed.
【0045】すなわち、前記多孔体を酸素含有雰囲気下
に熱処理することにより、高純度ケイ素化合物原料に起
因した数ppmから数十ppm程度の≡Si−H結合や
≡Si−Cl結合が1ppm以下になり、シラン等の単
なる分解反応による≡Si−Si≡結合の生成が防止さ
れ、また一旦生成した≡Si−Si≡が雰囲気中の酸素
により正常な≡Si−O−Si≡結合に変化する。That is, by subjecting the porous body to a heat treatment in an oxygen-containing atmosphere, the ≡Si—H bond or −Si—Cl bond of several ppm to several tens ppm due to the high-purity silicon compound raw material is reduced to 1 ppm or less. Thus, the formation of the {Si-Si} bond due to a simple decomposition reaction of silane or the like is prevented, and the once formed {Si-Si} changes to a normal {Si-O-Si} bond due to oxygen in the atmosphere.
【0046】次に、脱ガス処理により、上記した酸素ガ
ス処理の余剰酸素やその他のガス成分がガラス微粒子中
から除去され、後の工程において石英ガラス中へH2 の
拡散が容易になる。Next, by the degassing treatment, the excess oxygen and other gas components of the above-described oxygen gas treatment are removed from the glass fine particles, and the diffusion of H 2 into the quartz glass in a later step becomes easy.
【0047】水素含有雰囲気下での熱処理はその温度が
700℃を超えると、徐々に下記の数8式に示すよう
な、≡Si−O−Si≡とH2 ガスとの反応が進行し始
め、800℃を超える温度では≡Si−Hの生成が非常
に顕著となり、この≡Si−Hは酸素欠乏欠陥≡Si・
発生の原因となるので好ましくない。In the heat treatment in a hydrogen-containing atmosphere, when the temperature exceeds 700 ° C., the reaction between {Si—O—Si} and H 2 gas starts to progress gradually as shown in the following equation (8). At a temperature exceeding 800 ° C., the formation of ≡Si—H becomes very remarkable.
It is not preferable because it causes generation.
【0048】[0048]
【数8】 (Equation 8)
【0049】[0049]
【実施例及び比較例】以下、本発明の実施例に係る光透
過用合成石英ガラスを説明する。なお、比較例として、
KrFレーザの照射により透過率の低下が大きい合成石
英ガラスについても説明する。Examples and Comparative Examples Hereinafter, synthetic quartz glass for light transmission according to examples of the present invention will be described. In addition, as a comparative example,
A description will also be given of synthetic quartz glass in which the transmittance is greatly reduced by irradiation with a KrF laser.
【0050】高純度ケイ素化合物である四塩化ケイ素
(SiCl4 )を原料とし、酸素−水素火炎中、180
0℃で気相化学反応により石英ガラス微粒子を合成する
とともにこれを堆積させ、その直径が35cmで長さが
100cmの多孔体(スート)を合成した。Using silicon tetrachloride (SiCl 4 ), which is a high-purity silicon compound, as a raw material, an oxygen-hydrogen flame, 180
Fine silica glass particles were synthesized and deposited by gas phase chemical reaction at 0 ° C., and a porous body (soot) having a diameter of 35 cm and a length of 100 cm was synthesized.
【0051】次に、この合成された多孔体を種々の条件
で熱処理することにより石英ガラスロッド(プリフォー
ム)を作製した。まず、実施例1、2、及び比較例1、
4の場合はこの多孔体を雰囲気炉に入れ、100%の酸
素雰囲気下、1200℃で6時間熱処理し、次に真空炉
に移しかえて0.5Paの減圧下、1250℃で48時
間熱処理した後、さらに1550℃で6時間熱処理を行
って焼結させ、緻密で透明な石英ガラスロッドを得た。
また、実施例3の場合には最初の工程である酸素雰囲気
下での熱処理を省略し、実施例4の場合には前記酸素雰
囲気下での熱処理の代わりに真空雰囲気下、1200℃
で6時間熱処理を行った以外は、実施例1の場合と同様
にその他の熱処理を行った。さらに、比較例2、5の場
合には酸素雰囲気の代わりに塩素を5%含有したHeガ
ス中、1200℃で6時間処理し、比較例3、6の場合
には前記塩素を含有したHeガス中での熱処理の後に純
Heガス雰囲気中、1500℃で10時間熱処理を行っ
た以外は、実施例1の場合と同様にその後の熱処理を行
った。Next, the synthesized porous body was heat-treated under various conditions to prepare a quartz glass rod (preform). First, Examples 1 and 2, and Comparative Example 1,
In the case of No. 4, this porous body was placed in an atmosphere furnace and heat-treated at 1200 ° C. for 6 hours in a 100% oxygen atmosphere, and then transferred to a vacuum furnace and heat-treated at 1250 ° C. for 48 hours under a reduced pressure of 0.5 Pa. Thereafter, heat treatment was further performed at 1550 ° C. for 6 hours for sintering to obtain a dense and transparent quartz glass rod.
Further, in the case of the third embodiment, the first step of the heat treatment in the oxygen atmosphere is omitted, and in the case of the fourth embodiment, the heat treatment in the oxygen atmosphere is replaced with a 1200 ° C.
Other heat treatments were performed in the same manner as in Example 1 except that the heat treatment was performed for 6 hours. Further, in Comparative Examples 2 and 5, a treatment was performed at 1200 ° C. for 6 hours in a He gas containing 5% chlorine instead of an oxygen atmosphere, and in Comparative Examples 3 and 6, the He gas containing chlorine was used. A heat treatment was performed in the same manner as in Example 1 except that a heat treatment was performed at 1500 ° C. for 10 hours in a pure He gas atmosphere after the heat treatment in the inside.
【0052】前記熱処理により得られた石英ガラスロッ
ド(プリフォーム)は、いずれの場合においてもその直
径が120mmで長さが約650mmであった。次に、
これらプリフォームをそれぞれスライス処理し、厚さが
10mmの円板状体を作製した。The quartz glass rod (preform) obtained by the heat treatment had a diameter of 120 mm and a length of about 650 mm in each case. next,
Each of these preforms was sliced to produce a disc having a thickness of 10 mm.
【0053】次に、実施例1、3、4及び比較例2、3
の場合には、前記円板状体をH2 ガス1気圧の雰囲気
下、700℃で熱処理することにより、前記円板状体に
H2 を含有させた。前記水素含有雰囲気での熱処理時間
は、実施例1の場合は1時間と、実施例3、及び比較例
2、3の場合は5時間とし、実施例4の場合は100時
間とした。また、実施例2の場合には水素含有雰囲気下
での熱処理条件を750℃、5時間とし、比較例1の場
合には1000℃、5時間とした。比較例4〜6の場合
には水素含有雰囲気下での熱処理は行わなかった。Next, Examples 1, 3, and 4 and Comparative Examples 2, 3
In the case of (1), the disc-shaped body was heat-treated at 700 ° C. in an atmosphere of 1 atmosphere of H 2 gas, so that the disc-shaped body contained H 2 . The heat treatment time in the hydrogen-containing atmosphere was 1 hour in Example 1, 5 hours in Example 3, and Comparative Examples 2 and 3, and 100 hours in Example 4. In the case of Example 2, the heat treatment condition in a hydrogen-containing atmosphere was set to 750 ° C. for 5 hours, and in the case of Comparative Example 1, the temperature was set to 1000 ° C. for 5 hours. In the case of Comparative Examples 4 to 6, no heat treatment was performed in a hydrogen-containing atmosphere.
【0054】以上のような条件で製造された円板状の石
英ガラス中のH2 濃度、SiH基の濃度、≡Si−Si
≡の濃度、及びSiCl基の濃度を、「作用」の欄で記
載した方法により測定した。その結果を下記の表1に示
している。The H 2 concentration, SiH group concentration, ΔSi—Si in the disc-shaped quartz glass manufactured under the above conditions,
The concentration of ≡ and the concentration of SiCl groups were measured by the method described in the column of “Action”. The results are shown in Table 1 below.
【0055】このような特性を有する実施例及び比較例
に係る石英ガラス(直径:120mm、厚さ:10m
m)に、248nmのKrFエキシマレーザーを400
mJ/cm2 、100Hzの条件で106 ショット照射
し、その前後で248nm、193nm、185nmの
各波長の透過率を測定し、透過率の低下に関する評価を
行った。また、前記KrFエキシマレーザー照射後に2
60nmにおける透過率を測定した。結果を同じく下記
の表1に示している。The quartz glass according to Examples and Comparative Examples having such characteristics (diameter: 120 mm, thickness: 10 m)
m), a KrF excimer laser of 248 nm
Irradiation was performed for 10 6 shots under the conditions of mJ / cm 2 and 100 Hz, and before and after that, the transmittance at each wavelength of 248 nm, 193 nm, and 185 nm was measured, and the reduction in transmittance was evaluated. Further, after the KrF excimer laser irradiation,
The transmittance at 60 nm was measured. The results are also shown in Table 1 below.
【0056】なお、表1では、KrFエキシマレーザー
による耐光性の評価のみを示したが、ArFエキシマレ
ーザー、低圧水銀ランプ、エキシマランプを用いた場合
でも、紫外線を照射した際の光損傷による透過率低下挙
動は全く同様であるため、同様の結果が得られた。In Table 1, only the evaluation of light resistance by the KrF excimer laser is shown. However, even when an ArF excimer laser, a low-pressure mercury lamp, and an excimer lamp are used, the transmittance due to light damage when irradiated with ultraviolet rays is also shown. Since the lowering behavior was exactly the same, similar results were obtained.
【0057】[0057]
【表1】 [Table 1]
【0058】上記の表1に示した結果より明らかなよう
に、H2 を1015個/cm3 以上の濃度で含有する実施
例1〜4に係る石英ガラスは、レーザー照射後の光吸収
スペクトルから260nm帯欠陥による吸収は認めら
ず、また、シリル基(SiH)の濃度、酸素欠乏欠陥濃
度の2倍及びSiCl基の濃度の和が5.3×1016個
/cm3 以下であり、210nm帯の吸収が痕跡程度あ
るいは検出されず、各波長の透過率低下は0.2%以下
となり、真空紫外域〜紫外域での高エネルギー光に対す
る優れた耐光性が確認された。As is clear from the results shown in Table 1 above, the quartz glasses according to Examples 1 to 4 containing H 2 at a concentration of 10 15 / cm 3 or more showed light absorption spectra after laser irradiation. No absorption due to defects at 260 nm band is recognized, and the sum of the silyl group (SiH) concentration, twice the oxygen deficiency defect concentration and the SiCl group concentration is 5.3 × 10 16 / cm 3 or less, The absorption in the 210 nm band was almost no trace or detected, and the decrease in transmittance at each wavelength was 0.2% or less, and excellent light resistance to high energy light in the vacuum ultraviolet region to the ultraviolet region was confirmed.
【0059】他方比較例1の場合には、H2 処理温度が
高すぎ、石英ガラスのネットワーク構造中のSiとH2
分子が反応してシリル基が多量に生成しており、これに
より、石英ガラス中にH2 は充分存在するにも拘らず2
10nm帯欠陥による吸収が大きくなり、各波長の透過
率が大きく低下している。また、比較例2、3の場合に
おいても、石英ガラス中にH2 は充分存在するにも拘ら
ず、シリル基濃度、酸素欠乏欠陥濃度の2倍及び≡Si
−Cl濃度の和が5.3×1016個/cm3 を超えてお
り、210nm帯の吸収が大きくなり、各波長の透過率
が低下している。さらに、比較例4〜6の場合には、H
2 分子が検出されず、かつシリル基濃度、酸素欠乏欠陥
濃度の2倍及び≡Si−Cl濃度の和が5.3×1016
個/cm3 を超えており、260nm、210nm帯の
吸収が顕著となり、各波長域の透過率が大きく低下して
いる。特に、260nm帯欠陥の存在により248nm
での透過率の低下が顕著となっている。On the other hand, in the case of Comparative Example 1, the H 2 treatment temperature was too high, and Si and H 2 in the quartz glass network structure were changed.
Molecules are silyl groups by reaction generates a large amount, regardless Thus, also in H 2 is present sufficiently in the quartz glass 2
The absorption due to the 10 nm band defect increases, and the transmittance at each wavelength decreases significantly. In Comparative Examples 2 and 3, even though H 2 was sufficiently present in the quartz glass, the silyl group concentration, twice the oxygen deficiency defect concentration, and ΔSi
The sum of the -Cl concentration exceeds 5.3 × 10 16 / cm 3 , the absorption in the 210 nm band increases, and the transmittance at each wavelength decreases. Furthermore, in Comparative Examples 4 to 6, H
Two molecules were not detected, and the sum of the silyl group concentration, twice the oxygen deficiency defect concentration, and the ΔSi—Cl concentration was 5.3 × 10 16
/ Cm 3 , the absorption in the 260 nm and 210 nm bands becomes remarkable, and the transmittance in each wavelength region is greatly reduced. In particular, 248 nm due to the presence of a 260 nm band defect.
, The decrease in transmittance is remarkable.
【0060】[0060]
【発明の効果】以上詳述したように本発明に係る光透過
用合成石英ガラスにあっては、溶存水素分子濃度が10
15個/cm3 以上であり、かつSiH基の濃度、酸素欠
乏欠陥濃度の2倍及びSiCl基の濃度の合計が5.3
×1016個/cm3 以下であるので、真空紫外域〜紫外
域の高エネルギー密度の光が照射された場合でも、21
0nm帯欠陥び及び260nm帯欠陥が生成せず、前記
波長領域における吸収を防止することができ、耐光性に
優れた光透過用合成石英ガラスを提供することができ
る。従って、本発明に係る光透過用合成石英ガラスは、
エキシマレーザー発振装置、リソグラフィー用レーザー
露光装置、レーザーCVD装置、アッシャー、エッチャ
ー、オゾナイザー、レーザー加工装置、レーザー医療装
置等の真空紫外域〜紫外域のレーザー及びランプを利用
した各種装置の窓材、レンズ、ミラー、プリズム、ラン
プ用のガス封入容器等、種々の用途に用いることができ
る。As described in detail above, the synthetic quartz glass for light transmission according to the present invention has a dissolved hydrogen molecule concentration of 10%.
15 / cm 3 or more, and the total of the SiH group concentration, twice the oxygen deficiency defect concentration and the SiCl group concentration is 5.3.
× 10 16 / cm 3 or less, so that even when irradiated with light of high energy density in the vacuum ultraviolet
A 0-nm band defect and a 260-nm band defect are not generated, the absorption in the wavelength region can be prevented, and a synthetic quartz glass for light transmission excellent in light resistance can be provided. Therefore, the synthetic quartz glass for light transmission according to the present invention,
Window materials and lenses for various devices that use vacuum ultraviolet to ultraviolet lasers and lamps, such as excimer laser oscillation devices, lithography laser exposure devices, laser CVD devices, ashers, etchers, ozonizers, laser processing devices, and laser medical devices. , Mirrors, prisms, gas-filled containers for lamps, etc.
【0061】また、本願発明に係る光透過用合成石英ガ
ラスの製造方法にあっては、高純度ケイ素化合物から気
相化学反応により石英ガラス多孔体を合成し、前記石英
ガラス多孔体を酸素含有雰囲気中で熱処理した後に真空
下で透明ガラス化することにより得られた酸素過剰型欠
陥を含む合成石英ガラスを、水素含有雰囲気下800℃
以下で熱処理するので、前記した耐光性に優れた光透過
用合成石英ガラスを確実に製造することができる。In the method for producing a synthetic quartz glass for light transmission according to the present invention, a quartz glass porous body is synthesized from a high-purity silicon compound by a gas phase chemical reaction, and the quartz glass porous body is subjected to an oxygen-containing atmosphere. A synthetic quartz glass containing oxygen-excess type defects obtained by performing vitrification under vacuum after heat treatment in vacuum at 800 ° C. in a hydrogen-containing atmosphere.
Since the heat treatment is performed below, the synthetic quartz glass for light transmission having excellent light resistance can be reliably manufactured.
【図1】従来の合成石英ガラスにKrFエキシマレーザ
ーを照射した際に生じる欠陥による真空紫外域〜紫外域
での吸収を示したグラフである。FIG. 1 is a graph showing absorption in a vacuum ultraviolet region to an ultraviolet region due to a defect generated when a conventional synthetic quartz glass is irradiated with a KrF excimer laser.
【図2】水素を含有する合成石英ガラスにKrFエキシ
マレーザーを照射した際の真空紫外域〜紫外域での吸収
を示したグラフである。FIG. 2 is a graph showing absorption in a vacuum ultraviolet region to an ultraviolet region when a synthetic quartz glass containing hydrogen is irradiated with a KrF excimer laser.
【図3】210nm(5.9eV)帯欠陥の各吸光度に
おける吸収ピークの形状を示したグラフである。FIG. 3 is a graph showing the shape of an absorption peak at each absorbance of a 210 nm (5.9 eV) band defect.
【図4】210nm欠陥の吸光度が特定波長域(248
nm、193nm、185nm)での透過率に及ぼす影
響を示したグラフである。FIG. 4 shows the absorbance of a 210 nm defect in a specific wavelength range (248
9 is a graph showing the effect on the transmittance at 193 nm and 185 nm).
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平4−21540(JP,A) 特開 平4−195101(JP,A) 特開 平6−234545(JP,A) N.Kuzuu,Physical Review B,(US),The American Physical Society,1991,米国,Vol. 44,No.17,p.9265−9270 昭和63年度 シリカガラスデータブッ ク,日本,社団法人ニューガラスフォー ラム,1990年 3月 1日,p.59−61 (58)調査した分野(Int.Cl.7,DB名) C03B 8/04 C03B 20/00 C03C 3/06 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-21540 (JP, A) JP-A-4-195101 (JP, A) JP-A-6-234545 (JP, A) Kuzuu, Physical Review B, (US), The American Physical Society, 1991, USA, Vol. 17, p. 9265-9270 Silica Glass Data Book, 1988, New Glass Forum, Japan, March 1, 1990, p. 59-61 (58) Field surveyed (Int. Cl. 7 , DB name) C03B 8/04 C03B 20/00 C03C 3/06
Claims (1)
より石英ガラス多孔体を合成し、前記石英ガラス多孔体
を酸素含有雰囲気中で熱処理した後に真空下で透明ガラ
ス化することにより得られた酸素過剰型欠陥を含む合成
石英ガラスを、水素含有雰囲気下 800℃以下で熱処理す
ることを特徴とする溶存水素分子濃度が10 15 個/cm 3 以上
であり、かつSiH 基の濃度、酸素欠乏欠陥濃度の2倍及
びSiCl基の濃度の合計が 5.3×10 16 個/cm 3 以下である光
透過用合成石英ガラスの製造方法。1. An oxygen obtained by synthesizing a porous quartz glass body from a high-purity silicon compound by a gas phase chemical reaction, heat-treating the porous quartz glass body in an oxygen-containing atmosphere, and then vitrifying it under vacuum. The synthetic quartz glass containing excess defects is heat-treated at 800 ° C or less in a hydrogen-containing atmosphere. The dissolved hydrogen molecule concentration is 10 15 / cm 3 or more.
And twice the concentration of SiH groups and oxygen deficiency defects
A method for producing a synthetic quartz glass for light transmission, wherein the total concentration of SiCl and SiCl groups is 5.3 × 10 16 / cm 3 or less .
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EP0870737B1 (en) | 1997-04-08 | 2002-07-24 | Shin-Etsu Quartz Products Co., Ltd. | Optical synthetic quartz glass, production method thereof, and optical member for excimer laser using the synthetic quartz glass |
US8402786B2 (en) | 1998-01-30 | 2013-03-26 | Asahi Glass Company, Limited | Synthetic silica glass optical component and process for its production |
JP4011217B2 (en) * | 1998-12-25 | 2007-11-21 | 信越石英株式会社 | Manufacturing method of optical quartz glass for excimer laser |
JP4439072B2 (en) * | 2000-03-29 | 2010-03-24 | 信越石英株式会社 | Synthetic quartz glass for optics, heat treatment method and heat treatment apparatus thereof |
JP4462720B2 (en) * | 2000-06-06 | 2010-05-12 | 信越石英株式会社 | Heat treatment method for optical synthetic quartz glass |
JP4470479B2 (en) | 2003-12-17 | 2010-06-02 | 旭硝子株式会社 | Synthetic quartz glass for optical members and method for producing the same |
DE102004018887B4 (en) * | 2004-04-15 | 2009-04-16 | Heraeus Quarzglas Gmbh & Co. Kg | A method of manufacturing a quartz glass component for use with a source of ultraviolet rays and a method of aptitude diagnosis of such a quartz glass component |
DE102006043368B4 (en) * | 2005-09-16 | 2019-01-10 | Corning Inc. | Synthetic silicic acid glass and process for producing the same |
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1994
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Non-Patent Citations (2)
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N.Kuzuu,Physical Review B,(US),The American Physical Society,1991,米国,Vol.44,No.17,p.9265−9270 |
昭和63年度 シリカガラスデータブック,日本,社団法人ニューガラスフォーラム,1990年 3月 1日,p.59−61 |
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