JP2003183034A - Synthetic quartz glass for optical member and its manufacturing method - Google Patents
Synthetic quartz glass for optical member and its manufacturing methodInfo
- Publication number
- JP2003183034A JP2003183034A JP2001384424A JP2001384424A JP2003183034A JP 2003183034 A JP2003183034 A JP 2003183034A JP 2001384424 A JP2001384424 A JP 2001384424A JP 2001384424 A JP2001384424 A JP 2001384424A JP 2003183034 A JP2003183034 A JP 2003183034A
- Authority
- JP
- Japan
- Prior art keywords
- quartz glass
- optical member
- synthetic quartz
- fluorine
- less
- 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.)
- Pending
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
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B19/00—Other methods of shaping glass
- C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
- C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
- C03B19/1461—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering for doping the shaped article with flourine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/07—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
- C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
- C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
-
- 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)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、波長155〜25
0nmの光を光源とする光学装置の光学部材用合成石英
ガラスおよびその製造方法に関する。より詳細には、A
rFエキシマレーザ(波長193nm)、Xe2エキシ
マランプ(波長172nm)や重水素ランプ(波長17
0〜400nm)、F2レーザ(波長157nm)等を
光源とした光学装置の、レンズ、プリズム、エタロン、
回折格子、フォトマスク、ペリクル(ペリクル材および
ペリクルフレーム)、窓材などの光学部品材料として用
いられる光学部材用合成石英ガラスとその製造方法に関
する。TECHNICAL FIELD The present invention relates to wavelengths of 155 to 25.
The present invention relates to a synthetic quartz glass for an optical member of an optical device using 0 nm light as a light source and a method for manufacturing the same. More specifically, A
rF excimer laser (wavelength 193 nm), Xe 2 excimer lamp (wavelength 172 nm) and deuterium lamp (wavelength 17
0-400 nm), F 2 laser (wavelength 157 nm), etc.
The present invention relates to a synthetic quartz glass for an optical member used as an optical component material such as a diffraction grating, a photomask, a pellicle (a pellicle material and a pellicle frame), a window material, and a manufacturing method thereof.
【0002】[0002]
【従来の技術】従来から、光リソグラフィ技術におい
て、ウエハ上に微細な回路パターンを転写して集積回路
を製造するための露光装置が広く利用されている。集積
回路の高集積化および高機能化に伴い、集積回路の微細
化が進み、高解像度の回路パターンを深い焦点深度でウ
エハ面上に結像させることが露光装置に求められ、露光
光源の短波長化が進められている。露光光源は、従来の
g線(波長436nm)やi線(波長365nm)から
進んで、KrFエキシマレーザ(波長248nm)やA
rFエキシマレーザ(波長193nm)が用いられよう
としている。またさらに回路パターンが100nm以下
となる次世代の集積回路に対応するため、露光光源とし
てF2レーザ(波長157.6nm)を用いることが検
討され始めている。2. Description of the Related Art Conventionally, in an optical lithography technique, an exposure apparatus for transferring a fine circuit pattern onto a wafer to manufacture an integrated circuit has been widely used. As integrated circuits have become highly integrated and highly functionalized, miniaturization of integrated circuits has progressed, and it is required for an exposure apparatus to form a high-resolution circuit pattern on a wafer surface with a deep depth of focus. Wavelength conversion is in progress. The exposure light source is advanced from the conventional g-line (wavelength 436 nm) or i-line (wavelength 365 nm), and the KrF excimer laser (wavelength 248 nm) or A
An rF excimer laser (wavelength 193 nm) is about to be used. Further, in order to cope with a next-generation integrated circuit having a circuit pattern of 100 nm or less, the use of an F 2 laser (wavelength 157.6 nm) as an exposure light source is being studied.
【0003】波長155〜400nmの光を光源とする
光源とする露光装置の光学系には、近赤外域から紫外域
までの広範囲にわたって透過性に優れ、熱膨張係数が極
めて小さく加工が比較的容易などの理由から、合成石英
ガラスが主に用いられてきた。従来用いられてきた合成
石英ガラスは、例えば特開平3−88742公報に開示
されたものが知られている。In an optical system of an exposure apparatus having a light source having a wavelength of 155 to 400 nm as a light source, the optical system has excellent transparency over a wide range from the near infrared region to the ultraviolet region, has a very small coefficient of thermal expansion, and is relatively easy to process. For these reasons, synthetic quartz glass has been mainly used. As the synthetic quartz glass that has been conventionally used, for example, one disclosed in Japanese Patent Laid-Open No. 3-88742 is known.
【0004】すなわち合成石英ガラス体中のOH基含有
量が10ppm以上であり、かつ水素を5×1016分
子/cm3以上含有することを特徴とするものである。
しかしながら同報発明の合成石英ガラスであっても、紫
外線を照射した場合に屈折率の上昇や透過率低下などの
ダメージが生じ問題であった。KrFエキシマレーザ、
ArFエキシマレーザさらにはF2レーザと光の波長が
短くなるにつれ光子の持つエネルギーが増すため、波長
200nm以下の深紫外光〜真空紫外光に対する耐光性
は特に問題であった。That is, the synthetic quartz glass body is characterized by having an OH group content of 10 ppm or more and hydrogen of 5 × 10 16 molecules / cm 3 or more.
However, even the synthetic quartz glass of the same invention has a problem that when it is irradiated with ultraviolet rays, damage such as increase in refractive index and decrease in transmittance occurs. KrF excimer laser,
Since the energy of photons increases as the wavelengths of ArF excimer laser and F 2 laser become shorter, the light resistance to deep ultraviolet light to vacuum ultraviolet light having a wavelength of 200 nm or less has been a particular problem.
【0005】紫外線を照射した場合の屈折率上昇や透過
率低下の原因は明確ではないが、合成石英ガラス中の歪
んだ構造、例えば三員環構造や四員環構造などの欠陥前
駆体が紫外線照射により切断され、E’センターやNB
OHCなどの構造欠陥が生成するためと推定される。ま
た合成石英ガラス中のOH基は、紫外線照射時の赤色蛍
光発光に影響を与えるだけでなく、波長180nm以下
の真空紫外域における光透過性を低下させる。したがっ
て合成石英ガラス中のOH基含有量は少ないほうが好ま
しい。The cause of the increase in the refractive index and the decrease in the transmittance when irradiated with ultraviolet rays is not clear, but the defect precursors such as the distorted structure in the synthetic quartz glass, for example, the three-membered ring structure and the four-membered ring structure are ultraviolet rays. Cut by irradiation, E'center and NB
It is presumed that structural defects such as OHC are generated. Further, the OH group in the synthetic quartz glass not only affects the red fluorescence emission at the time of ultraviolet irradiation, but also reduces the light transmittance in the vacuum ultraviolet region having a wavelength of 180 nm or less. Therefore, it is preferable that the OH group content in the synthetic quartz glass is small.
【0006】そこで耐光性、さらには真空紫外域におけ
る光透過性を改善する方法として、本発明者らは、特開
平2001−19450公報にて、フッ素を含有しかつ
OH基含有量が100ppm未満であることを特徴とす
る光学部材用合成石英ガラスを提案した。このように合
成石英ガラス内にフッ素を含有させることにより、合成
石英ガラス中のひずんだ構造が低減され、紫外線照射し
た場合のダメージは低減される。一方、光学部材用合成
石英ガラスにはその使用領域において屈折率が均一であ
ること(以下「屈折率均質性」という)が要求される
が、合成石英ガラス中のフッ素は屈折率を下げる効果が
あり、合成石英ガラス中のフッ素含有量バラツキは少な
いことが望ましい。Therefore, as a method for improving the light resistance and further the light transmission in the vacuum ultraviolet region, the present inventors have disclosed in JP-A No. 2001-19450 that fluorine is contained and the OH group content is less than 100 ppm. We have proposed a synthetic quartz glass for optical members, which is characterized by the following. By containing fluorine in the synthetic quartz glass in this manner, the distorted structure in the synthetic quartz glass is reduced, and damage caused by irradiation with ultraviolet rays is reduced. On the other hand, synthetic quartz glass for optical members is required to have a uniform refractive index (hereinafter referred to as “refractive index homogeneity”) in its usage region, but fluorine in synthetic quartz glass has an effect of lowering the refractive index. Therefore, it is desirable that the variation in fluorine content in the synthetic quartz glass is small.
【0007】このようなフッ素含有量を均一に含有しO
H基含有量の少ない合成石英ガラスの製造方法として、
特開2001−151531公報において、フッ素を含
有した合成石英ガラスを溶融回転撹拌処理することによ
り合成石英ガラス中のフッ素含有量分布を均一化し、フ
ッ素含有量の分布に優れた合成石英ガラスを作製する方
法が提案されている。しかしながら本発明者らがフッ素
含有合成石英ガラスの同作製方法および得られた合成石
英ガラスの特性などを詳細に検討した結果、フッ素含有
量を均一化させるための溶融回転撹拌処理には非常に高
温を要するためアルカリ金属などの不純物が混入する可
能性がある、プロパンガス火炎などにより加熱するため
合成石英ガラス中のOH基含有量が増える可能性がある
などの問題点を有し、高純度でかつOH基含有量が少な
く、フッ素含有量が均一な合成石英ガラスを安定して得
ることができなかった。Such a fluorine content is uniformly contained and O
As a method for producing synthetic quartz glass having a low H group content,
In Japanese Unexamined Patent Application Publication No. 2001-151531, by melting and stirring a synthetic quartz glass containing fluorine, the fluorine content distribution in the synthetic quartz glass is made uniform, and a synthetic quartz glass having an excellent fluorine content distribution is produced. A method has been proposed. However, as a result of detailed investigations by the present inventors on the method of producing the fluorine-containing synthetic quartz glass and the properties of the obtained synthetic quartz glass, it was found that a very high temperature was required for the melt rotary stirring treatment to make the fluorine content uniform. Therefore, impurities such as alkali metal may be mixed in, and heating with a propane gas flame may increase the OH group content in the synthetic quartz glass. Moreover, it was not possible to stably obtain a synthetic quartz glass having a low OH group content and a uniform fluorine content.
【0008】[0008]
【発明が解決しようとする課題】本発明は、フッ素含有
量の均一性に優れたフッ素含有合成石英ガラスを安定し
て作製する方法ならびに、屈折率均質性、耐光性および
光透過性に優れたフッ素含有合成石英ガラスの提供を目
的とする。DISCLOSURE OF THE INVENTION The present invention provides a method for stably producing a fluorine-containing synthetic quartz glass having an excellent fluorine content uniformity, and an excellent refractive index homogeneity, light resistance and light transmission. It is intended to provide a fluorine-containing synthetic quartz glass.
【0009】[0009]
【課題を解決するための手段】本発明者らは、合成石英
ガラス中のフッ素含有量に分布が生じる原因について鋭
意検討を行った結果、多孔質石英ガラスを所定の雰囲
気、条件にて処理することにより、多孔質石英ガラスの
OH基含有量の低減化を行った後、多孔質石英ガラスを
フッ素含有雰囲気下に保持し、多孔質石英ガラスをフッ
素ドープさせると同時にOH基含有量を低減する工程に
おいて、該多孔質石英ガラスの平均かさ密度およびその
分布が、最終的に得られる合成石英ガラス中のフッ素含
有量の分布に大きな影響を及ぼすことを見出した。Means for Solving the Problems The inventors of the present invention have made extensive studies as to the cause of the distribution of the fluorine content in synthetic quartz glass, and as a result, treat porous quartz glass in a prescribed atmosphere and conditions. As a result, after the OH group content of the porous quartz glass is reduced, the porous quartz glass is kept in a fluorine-containing atmosphere to dope the porous quartz glass with fluorine and simultaneously reduce the OH group content. In the process, it was found that the average bulk density of the porous quartz glass and its distribution have a great influence on the distribution of the fluorine content in the finally obtained synthetic quartz glass.
【0010】すなわち本発明は、波長155〜250n
mの光を光源とする光学装置の光学部材として用いられ
る光学部材用合成石英ガラスの製造方法において、
(a)ガラス形成原料を火炎加水分解して得られる石英
ガラス微粒子を基材に堆積・成長させて多孔質石英ガラ
スを形成する工程と、(b)該多孔質石英ガラスのOH
基含有量を低減する工程と、(c)該多孔質石英ガラス
をフッ素化合物含有雰囲気下に保持し、該多孔質石英ガ
ラスにフッ素をドープする工程と、(d)該多孔質石英
ガラスを1300℃以上の温度に昇温して透明ガラス化
し、フッ素を含有した透明石英ガラス体を得る工程と、
を含み、工程(b)における多孔質石英ガラスの平均か
さ密度が1.6g/cm3以下、かつ多孔質石英ガラス
の成長軸方向に垂直な断面において、外周から20mm
を除いた領域内でのかさ密度の最大と最小との差が0.
6g/cm3以下であることを特徴とする光学部材用合
成石英ガラスの製造方法を提供するものである。That is, the present invention has a wavelength of 155 to 250n.
In a method of manufacturing synthetic quartz glass for an optical member used as an optical member of an optical device using m light as a light source,
(A) a step of depositing and growing quartz glass fine particles obtained by flame hydrolysis of a glass forming raw material on a base material to form a porous quartz glass, and (b) OH of the porous quartz glass
A step of reducing the group content, (c) a step of holding the porous quartz glass in a fluorine compound-containing atmosphere and doping the porous quartz glass with fluorine, and (d) 1300 the porous quartz glass. A step of raising the temperature to ℃ or higher to obtain a transparent vitrified glass, and obtaining a transparent quartz glass body containing fluorine;
In the step (b), the average bulk density of the porous quartz glass in the step (b) is 1.6 g / cm 3 or less, and 20 mm from the outer periphery in a cross section perpendicular to the growth axis direction of the porous quartz glass.
The difference between the maximum and minimum bulk densities within the region excluding.
The present invention provides a method for producing synthetic quartz glass for optical members, which is 6 g / cm 3 or less.
【0011】[0011]
【発明の実施の形態】本発明の工程(a)は、多孔質石
英ガラスの製造工程である。多孔質ガラスの製造工程に
おいては、合成石英ガラスの形成原料を多重管バーナー
に供給し、火災加水分解して、得られる石英ガラス微粒
子を基材に堆積・成長させて多孔質石英ガラスを形成す
る。BEST MODE FOR CARRYING OUT THE INVENTION Step (a) of the present invention is a step for producing porous quartz glass. In the manufacturing process of porous glass, the raw material for forming synthetic quartz glass is supplied to a multi-tube burner, fire-hydrolyzed, and the resulting quartz glass particles are deposited and grown on a substrate to form porous quartz glass. .
【0012】合成石英ガラスの形成原料としては、ガス
化可能な原料であれば特に制限されないが、SiC
l4、SiHCl3、SiH2Cl2、SiCH3Cl
3などの塩化物、SiF4、SiHF3、SiH2F2
などのフッ化物、SiBr4、SiHBr3などの臭化
物、SiI4などの沃化物といったハロゲン化ケイ素化
合物、またはRnSi(OR)4−n(ここにRは炭素
数1〜4のアルキル基、nは0〜3の整数)で示される
アルコキシシランや(CH3)3Si−O−Si(CH
3)3などのハロゲンを含まないケイ素化合物が挙げら
れる。The raw material for forming the synthetic quartz glass is not particularly limited as long as it is a gasifiable raw material.
l 4 , SiHCl 3 , SiH 2 Cl 2 , SiCH 3 Cl
Chlorides such as 3 , SiF 4 , SiHF 3 , SiH 2 F 2
Fluorides such as, SiBr 4, SiHBr bromides such as 3, halogenated silicon compounds such as iodide such as SiI 4, or RnSi (OR) 4-n (wherein R is an alkyl group having 1 to 4 carbon atoms, n represents alkoxysilane represented by an integer of 0 to 3) or (CH 3) 3 Si-O -Si (CH
3 ) Halogen-free silicon compounds such as 3 are mentioned.
【0013】ガラス形成原料にハロゲン化ケイ素化合物
を用いる場合には、合成石英ガラス中にガラス形成原料
中のハロゲンが残留する場合があり、ハロゲンの残留含
有量にバラツキが生じ屈折率均質性を損なう可能性があ
る。したがって、ガラス形成原料としてはハロゲンを含
まない有機ケイ素化合物が好ましい。ただしハロゲンを
含まない有機ケイ素化合物は比較的高価であり、これを
ガラス形成原料に用いた場合には製造コストの上昇が避
けられない。そこで製造コストを抑制するためにハロゲ
ン化ケイ素化合物をガラス形成原料として用いる場合に
は、屈折率への影響が最も少ない塩化ケイ素化合物を使
用することが好ましい。When a halogenated silicon compound is used as the glass forming raw material, the halogen in the glass forming raw material may remain in the synthetic quartz glass, and the residual content of the halogen varies to impair the homogeneity of the refractive index. there is a possibility. Therefore, a halogen-free organosilicon compound is preferable as the glass forming raw material. However, the halogen-free organosilicon compound is relatively expensive, and when it is used as a glass forming raw material, an increase in manufacturing cost cannot be avoided. Therefore, when a silicon halide compound is used as a glass forming raw material in order to suppress the production cost, it is preferable to use a silicon chloride compound which has the least influence on the refractive index.
【0014】また石英ガラス微粒子を堆積・成長させる
基材は、得られる多孔質石英ガラスのかさ密度分布形状
を整える、回転対称にするという観点から、回転させる
ことが好ましい。回転速度は石英ガラス微粒子の堆積・
成長速度に依るが、毎分10回転〜0.1回転の範囲が
好ましい。The substrate on which the silica glass fine particles are deposited and grown is preferably rotated from the viewpoint of adjusting the bulk density distribution shape of the obtained porous silica glass and making it rotationally symmetric. The rotation speed is the deposition of quartz glass particles.
Although it depends on the growth rate, a range of 10 to 0.1 rotations per minute is preferable.
【0015】本発明の工程(b)は、OH基含有量を低
減する工程である。多孔質石英ガラスに含まれるOH基
の含有量を低減するためには、いくつかの方法が可能で
ある。具体的には、以下の方法が例示できるが、本発明
は、これらに限定されるものではない。
(方法1)該多孔質石英ガラスをフッ素化合物含有雰囲
気下に保持する。この場合はフッ素ドープが同時に行わ
れる。
(方法2)該多孔質石英ガラスを塩素化合物含有雰囲気
下に保持する。
(方法3)該多孔質石英ガラスを一酸化炭素含有雰囲気
下に保持する。
(方法4)該多孔質石英ガラスを水素ガス含有雰囲気下
に保持する。この場合は、多孔質石英ガラスに水素がド
ープされる。したがって、必要に応じて、ドープされた
水素の含有量低減処理が併用される。The step (b) of the present invention is a step of reducing the OH group content. Several methods are possible to reduce the content of OH groups contained in the porous quartz glass. Specifically, the following methods can be exemplified, but the present invention is not limited thereto. (Method 1) The porous quartz glass is kept in an atmosphere containing a fluorine compound. In this case, fluorine doping is simultaneously performed. (Method 2) The porous quartz glass is kept in an atmosphere containing a chlorine compound. (Method 3) The porous quartz glass is kept in an atmosphere containing carbon monoxide. (Method 4) The porous quartz glass is kept in an atmosphere containing hydrogen gas. In this case, the porous quartz glass is doped with hydrogen. Therefore, if necessary, a treatment for reducing the content of doped hydrogen is also used.
【0016】これら4つの方法の中では、最終的に得ら
れる合成石英ガラス中の残留塩素含有量が少ないことや
安全性が高いことから、方法1または方法4が好まし
い。方法1の場合には、OH基含有量低減工程(工程
(b))とフッ素ドープ工程(工程(c))を兼ねるこ
とができる。Of these four methods, Method 1 or Method 4 is preferable because the residual chlorine content in the finally obtained synthetic quartz glass is small and the safety is high. In the case of Method 1, the step of reducing the OH group content (step (b)) and the fluorine doping step (step (c)) can be combined.
【0017】また、本発明のOH基含有量低減工程にお
ける多孔質石英ガラスの平均かさ密度は1.6g/cm
3以下とされる。多孔質石英ガラスの平均かさ密度をこ
のように調整することにより、最終的に得られる合成石
英ガラス体中の平均フッ素濃度を制御することが可能で
ある。すなわち平均かさ密度が1.6g/cm3以下の
範囲内で、多孔質石英ガラスの平均かさ密度が小さいほ
ど平均フッ素濃度が比較的高い合成石英ガラス体が、逆
に多孔質石英ガラスの平均かさ密度が大きいほど平均フ
ッ素濃度が比較的低い合成石英ガラス体がそれぞれ最終
的に得られる。また多孔質石英ガラスの平均かさ密度が
1.6g/cm3を超える場合、多孔質石英ガラスを前
記4つの方法で処理しても、十分にOH基含有量の低減
を行うことができず、OH基含有量を十分に低減した多
孔質石英ガラスを得ることが困難となるおそれがある。The average bulk density of the porous quartz glass in the step of reducing the OH group content of the present invention is 1.6 g / cm.
It is set to 3 or less. By adjusting the average bulk density of the porous quartz glass in this way, it is possible to control the average fluorine concentration in the finally obtained synthetic quartz glass body. That is, in the range of average bulk density of 1.6 g / cm 3 or less, the smaller the average bulk density of the porous quartz glass, the higher the average fluorine concentration becomes. The higher the density, the finally obtained synthetic quartz glass bodies having a relatively low average fluorine concentration. When the average bulk density of the porous quartz glass exceeds 1.6 g / cm 3 , the OH group content cannot be sufficiently reduced even if the porous quartz glass is treated by the above four methods, It may be difficult to obtain porous quartz glass having a sufficiently reduced OH group content.
【0018】さらに本発明のOH基含有量低減工程にお
ける多孔質石英ガラスのかさ密度バラツキ量(以下、か
さ密度分布という)は0.6g/cm3以下とされる。
具体的には、多孔質石英ガラスの成長軸方向に垂直な断
面において、外周から20mmを除いた領域内でのかさ
密度の最大と最小との差が0.6g/cm3以下であ
る。このかさ密度分布は、0.4g/cm3以下である
ことが特に好ましい。かさ密度分布が0.6g/cm3
を超える場合、最終的に得られる合成石英ガラス体中の
フッ素含有量の分布が大きくなり、屈折率均質性が損な
われるおそれがある。Further, in the OH group content reducing step of the present invention, the porous quartz glass has a bulk density variation amount (hereinafter referred to as bulk density distribution) of 0.6 g / cm 3 or less.
Specifically, in the cross section perpendicular to the growth axis direction of the porous quartz glass, the difference between the maximum and the minimum of the bulk density within the region excluding 20 mm from the outer periphery is 0.6 g / cm 3 or less. This bulk density distribution is particularly preferably 0.4 g / cm 3 or less. Bulk density distribution is 0.6 g / cm 3
If it exceeds, the distribution of the fluorine content in the finally obtained synthetic quartz glass body becomes large, and the homogeneity of the refractive index may be impaired.
【0019】前記範囲の平均かさ密度を有し、かつ前記
範囲のかさ密度分布を有する多孔質石英ガラスは、多孔
質石英ガラスの形成条件を調整することにより制御する
ことが可能である。すなわち、ガラス形成原料および酸
素ガス、水素ガスの投入量を制御することにより、ガラ
ス形成原料が火炎加水分解反応を起こして酸化ケイ素と
なる反応場の温度を調整し、多孔質石英ガラスのかさ密
度およびその分布を制御することが可能である。具体的
にはガラス形成原料に対する酸素ガス、水素ガスの投入
量を相対的に増やすことにより、反応場の温度を高くす
ることができ、平均かさ密度の高い多孔質石英ガラスを
得ることができる。The porous quartz glass having the average bulk density in the above range and the bulk density distribution in the above range can be controlled by adjusting the conditions for forming the porous quartz glass. That is, by controlling the input amounts of the glass forming raw material and oxygen gas, hydrogen gas, the temperature of the reaction field where the glass forming raw material undergoes a flame hydrolysis reaction to become silicon oxide is adjusted, and the bulk density of the porous quartz glass is adjusted. And its distribution can be controlled. Specifically, by relatively increasing the amounts of oxygen gas and hydrogen gas to be added to the glass forming raw material, the temperature of the reaction field can be increased and porous quartz glass having a high average bulk density can be obtained.
【0020】また多孔質石英ガラスの製造工程とOH基
含有量を低減する工程との間にかさ密度調整工程を実施
してもよい(工程(e))。すなわち得られた多孔質石
英ガラスを1000〜1500℃の範囲内にて加熱する
ことにより多孔質石英ガラスの平均かさ密度あるいはか
さ密度分布を調整することができる。具体的には、温度
1000〜1500℃に多孔質石英ガラスを加熱するこ
とにより、多孔質石英ガラスの平均かさ密度を全体的に
増加させ調整することができる。A bulk density adjusting step may be carried out between the step of producing the porous quartz glass and the step of reducing the OH group content (step (e)). That is, the average bulk density or bulk density distribution of the porous quartz glass can be adjusted by heating the obtained porous quartz glass in the range of 1000 to 1500 ° C. Specifically, by heating the porous quartz glass to a temperature of 1000 to 1500 ° C., it is possible to increase and adjust the average bulk density of the porous quartz glass as a whole.
【0021】また多孔質石英ガラスを加熱処理する際
に、故意に多孔質石英ガラス内に温度勾配をつけて多孔
質石英ガラスのかさ密度分布を調整することもできる。
例えば、表面近傍のかさ密度が内部のかさ密度に比べて
低い多孔質石英ガラスを、表面近傍の温度が高く内部の
温度が低くなるように加熱処理することにより、多孔質
石英ガラスのかさ密度分布を低減することができる。When the porous quartz glass is heat-treated, the bulk density distribution of the porous quartz glass can be adjusted by intentionally providing a temperature gradient in the porous quartz glass.
For example, by subjecting porous quartz glass whose bulk density in the vicinity of the surface is lower than that in the interior to heat treatment so that the temperature in the vicinity of the surface is high and the temperature in the interior is low, the bulk density distribution of the porous quartz glass Can be reduced.
【0022】本発明の工程(c)は、フッ素ドープ工程
である。The step (c) of the present invention is a fluorine doping step.
【0023】フッ素をドープするためには、多孔質石英
ガラス体をフッ素含有雰囲気中に保持する。フッ素含有
雰囲気としては、含フッ素ガス(例えばSiF4、SF
6、CHF3、CF4、F2など)を0.1〜50体積
%含有する不活性ガス雰囲気が好ましい。雰囲気温度は
室温〜1300℃が好ましい。In order to dope with fluorine, the porous quartz glass body is kept in a fluorine-containing atmosphere. The fluorine-containing atmosphere may be a fluorine-containing gas (eg, SiF 4 , SF
6 , CHF 3 , CF 4 , F 2 and the like) are preferably contained in an inert gas atmosphere of 0.1 to 50% by volume. The ambient temperature is preferably room temperature to 1300 ° C.
【0024】また、雰囲気圧力100Pa〜101kP
a(101kPa=大気圧)が好ましい。さらに、保持
時間は、数十分〜数十時間が好ましい。この場合、多孔
質石英ガラス体へ均一に短時間でフッ素をドープできる
ことから、減圧下(100Torr(13.3kPa)
以下、特に10Torr(1.33kPa)以下が好ま
しい。)で保持した状態で含フッ素ガスを常圧になるま
で導入し、フッ素含有雰囲気とすることが好ましい。ま
た400℃以上の高温でフッ素ドープする場合には、酸
素欠乏型欠陥などの還元型欠陥が生成しやすくなる。こ
のため、400℃以上の高温でフッ素ドープする場合
は、含フッ素ガスの他に酸素ガスを含んだ不活性ガス雰
囲気下で多孔質石英ガラス体を保持し、還元型欠陥の生
成を防ぐことが好ましい。Atmospheric pressure of 100 Pa to 101 kP
a (101 kPa = atmospheric pressure) is preferable. Further, the holding time is preferably tens of minutes to tens of hours. In this case, since it is possible to uniformly dope the porous quartz glass body with fluorine in a short time, it is possible to reduce the pressure (100 Torr (13.3 kPa)).
It is particularly preferably 10 Torr (1.33 kPa) or less. It is preferable to introduce a fluorine-containing gas until the pressure reaches normal pressure while maintaining the condition in (1) to make a fluorine-containing atmosphere. Further, when fluorine is doped at a high temperature of 400 ° C. or higher, reduction type defects such as oxygen deficiency type defects are likely to be generated. Therefore, when fluorine doping is performed at a high temperature of 400 ° C. or higher, it is possible to prevent the generation of reduction-type defects by holding the porous quartz glass body in an inert gas atmosphere containing oxygen gas in addition to fluorine-containing gas. preferable.
【0025】本発明の工程(d)は、透明ガラス化工程
である。透明ガラス化は、多孔質石英ガラスを所定の透
明ガラス化温度で所定時間保持することにより行われ
る。透明ガラス化温度は、通常は1300〜1600℃
であり、特に1350〜1500℃であることが好まし
い。またこの際の雰囲気としては、ヘリウムや窒素など
の不活性ガス100体積%の雰囲気、またはヘリウムや
窒素などの不活性ガスを主成分とする雰囲気を用いるこ
とができる。圧力については、減圧または常圧であれば
よい。特に常圧の場合にはヘリウムガスを用いることが
できる。また、減圧の場合には100Torr(13.
3kPa)以下とすることが好ましい。The step (d) of the present invention is a transparent vitrification step. The transparent vitrification is performed by maintaining the porous quartz glass at a predetermined transparent vitrification temperature for a predetermined time. The transparent vitrification temperature is usually 1300 to 1600 ° C.
And particularly preferably 1350 to 1500 ° C. As the atmosphere at this time, an atmosphere containing 100% by volume of an inert gas such as helium or nitrogen, or an atmosphere containing an inert gas such as helium or nitrogen as a main component can be used. The pressure may be reduced pressure or normal pressure. Helium gas can be used especially under normal pressure. In the case of decompression, 100 Torr (13.
It is preferably 3 kPa) or less.
【0026】本発明の方法により得られた合成石英ガラ
スは、露光装置用のレンズ、その他の光学部材として用
いるために、光学部材として必要な屈折率均質性や低複
屈折性などの光学特性を与えるための均質化、成形、ア
ニールなどの各熱処理(以下、光学的熱処理という)を
適宜行う必要がある。光学的熱処理は透明ガラス化の後
に行うことができる。The synthetic quartz glass obtained by the method of the present invention has optical properties such as a homogeneity of refractive index and a low birefringence necessary for an optical member in order to be used as a lens for an exposure apparatus and other optical members. It is necessary to appropriately perform each heat treatment such as homogenization, forming, and annealing (hereinafter referred to as an optical heat treatment) for giving. The optical heat treatment can be performed after the transparent vitrification.
【0027】特にアニールについては、アニールにより
合成石英ガラス中の三員環構造や四員環構造などの歪ん
だ構造を低減し、真空紫外域における光透過率や耐光性
を向上することができるため、実施することが好まし
い。具体的なアニール条件としては、合成石英ガラス
を、窒素ガスやアルゴンガスなどの不活性ガス雰囲気、
または空気、酸素ガス雰囲気中、温度600〜1100
℃、圧力101kPa(大気圧)〜1Paにて数十〜数
百時間保持することが好ましい。With respect to annealing, in particular, annealing can reduce distorted structures such as a three-membered ring structure and a four-membered ring structure in the synthetic quartz glass, and can improve light transmittance and light resistance in the vacuum ultraviolet region. , Is preferably carried out. Specific annealing conditions include synthetic quartz glass, an inert gas atmosphere such as nitrogen gas or argon gas,
Alternatively, in air or oxygen gas atmosphere, temperature 600 to 1100
It is preferable to maintain the temperature at a temperature of 101 kPa (atmospheric pressure) to 1 Pa for several tens to several hundreds of hours.
【0028】次に本発明の光学部材用合成石英ガラスの
組成について、説明する。本発明において、合成石英ガ
ラス中のOH基は、紫外線照射時の赤色蛍光発光を増加
させるだけでなく真空紫外域における光透過性を損なう
ため、その含有量は少ない方が好ましい。具体的には合
成石英ガラス中のOH基含有量は10ppm未満、特に
は5ppm以下が好ましく、特に、波長155〜180
nmの光を光源とする光学部材として用いる場合は、1
ppm以下が好ましい。Next, the composition of the synthetic quartz glass for optical members of the present invention will be described. In the present invention, the OH group in the synthetic quartz glass not only increases the red fluorescence emission upon irradiation with ultraviolet rays but also impairs the light transmittance in the vacuum ultraviolet region, so that the content thereof is preferably small. Specifically, the OH group content in the synthetic quartz glass is less than 10 ppm, particularly preferably 5 ppm or less, and particularly, the wavelength of 155 to 180
1 when used as an optical member using a light of nm as a light source
ppm or less is preferable.
【0029】本発明において、合成石英ガラス中の塩素
は、真空紫外域における光透過性および耐光性を悪化さ
せるため、その含有量が少ない方が好ましい。具体的に
は合成石英ガラス中の塩素含有量は10ppm以下、特
には5ppm以下、さらには実質的に含有しないことが
好ましい。In the present invention, the chlorine content in the synthetic quartz glass deteriorates the light transmittance and the light resistance in the vacuum ultraviolet region, so it is preferable that the content of chlorine is small. Specifically, the chlorine content in the synthetic quartz glass is 10 ppm or less, particularly 5 ppm or less, and further preferably substantially no chlorine.
【0030】本発明において、合成石英ガラス中のフッ
素は、OH基と置換しOH基含有量を低減する効果を有
するうえ、三員環構造、四員環構造などの歪んだ構造を
低減する効果がある。具体的には本発明の合成石英ガラ
スはフッ素を50ppm以上、特には200ppm以上
含有することが好ましい。In the present invention, fluorine in the synthetic quartz glass has the effect of substituting with OH groups to reduce the content of OH groups, and also has the effect of reducing distorted structures such as a three-membered ring structure and a four-membered ring structure. There is. Specifically, the synthetic quartz glass of the present invention preferably contains 50 ppm or more of fluorine, and particularly preferably 200 ppm or more.
【0031】また、フッ素含有量の分布は、光学部材と
しての使用領域において、フッ素含有量の最大と最小と
の差で250ppm以下であることが好ましく、特には
50ppm以下、さらに10ppm以下である。The distribution of the fluorine content is preferably 250 ppm or less, particularly 50 ppm or less, and more preferably 10 ppm or less in the range of use as an optical member, which is the difference between the maximum and the minimum of the fluorine content.
【0032】本発明において、合成石英ガラス中の酸素
欠乏型欠陥(≡Si−Si≡(≡は、Si−O結合を示
す。以下同様)、酸素過剰型欠陥(≡Si−O−O−S
i≡)、≡SiH結合、溶存酸素分子などは、真空紫外
光透過性および耐光性に悪影響を及ぼすため、実質的に
含有しない方が好ましい。特に、酸素欠乏欠陥は、OH
基含有量低減化の際に導入されやすいので、実質的に含
まれないよう、慎重に管理することが好ましい。In the present invention, oxygen-deficient type defects (≡Si—Si≡ (≡ represents Si—O bond; hereinafter the same)) and oxygen excess type defects (≡Si—O—O—S) in synthetic quartz glass.
i≡), ≡SiH bond, dissolved oxygen molecule and the like adversely affect the vacuum ultraviolet light transmittance and the light resistance, and thus it is preferable that they are not substantially contained. In particular, the oxygen deficiency defect is OH
Since it is likely to be introduced when reducing the group content, it is preferable to carefully control so that it is not substantially contained.
【0033】本発明において、合成石英ガラス中のアル
カリ金属(Na,K,Liなど)、アルカリ土類金属
(Mg,Caなど)、遷移金属(Fe,Ni,Cr,C
u,Mo,W,Al,Ti,Ceなど)などの金属不純
物は、紫外域から真空紫外域における透過率を低下させ
るだけでなく、耐紫外線性を低下させる原因ともなるた
め、その含有量は極力少ない方が好ましい。具体的には
金属不純物の合計含有量が100ppb以下、特に50
ppb以下が好ましい。In the present invention, alkali metals (Na, K, Li, etc.), alkaline earth metals (Mg, Ca, etc.), transition metals (Fe, Ni, Cr, C) in synthetic quartz glass are used.
Since metal impurities such as u, Mo, W, Al, Ti, and Ce) not only lower the transmittance in the ultraviolet region to the vacuum ultraviolet region but also reduce the ultraviolet resistance, their content is It is preferable that the number is as small as possible. Specifically, the total content of metal impurities is 100 ppb or less, especially 50
It is preferably ppb or less.
【0034】さらに本発明の方法により得られた合成石
英ガラスは、耐紫外線性を向上させるために、水素分子
を含有させると効果的な場合がある。具体的には合成石
英ガラスを水素含有雰囲気下、500℃以下の温度で加
熱処理することにより、合成石英ガラス中へ水素分子を
拡散、含有させる。Further, the synthetic quartz glass obtained by the method of the present invention may be effective in containing hydrogen molecules in order to improve the ultraviolet resistance. Specifically, synthetic quartz glass is heat-treated in a hydrogen-containing atmosphere at a temperature of 500 ° C. or lower to diffuse and contain hydrogen molecules in the synthetic quartz glass.
【0035】水素分子は紫外線照射により生じるE’セ
ンターやNBOHCなどの常磁性欠陥を修復し波長18
0〜300nmにおける吸収帯の生成を抑制するはたら
きを有する。波長180〜250nmの光を光源とする
光学装置の光学部材として用いる場合には、水素分子を
1×1017分子/cm3以上含有させることが好まし
い。The hydrogen molecule repairs paramagnetic defects such as E'center and NBOHC generated by ultraviolet irradiation and has a wavelength of 18
It has a function of suppressing the generation of an absorption band at 0 to 300 nm. When used as an optical member of an optical device that uses light having a wavelength of 180 to 250 nm as a light source, it is preferable that hydrogen molecules are contained in an amount of 1 × 10 17 molecules / cm 3 or more.
【0036】しかしながら、合成石英ガラス体中の水素
分子は紫外線照射中の酸素欠乏型欠陥(≡Si−Si
≡)生成を促進する作用があり、同欠陥は波長163n
mを中心とする吸収体を有するため、波長155〜18
0nmの光を光源とする光学装置の光学部材として用い
る場合には、合成石英ガラス中の水素分子含有量を1×
1017分子/cm3以下とすることが好ましい。な
お、用途、使用条件にもよるが、合成石英ガラス中の水
素分子含有量を1×1017分子/cm3以下とするこ
とが好ましい場合がある。However, hydrogen molecules in the synthetic quartz glass body are oxygen-deficient type defects (≡Si-Si) during ultraviolet irradiation.
≡) has the effect of promoting the generation, and the defect has a wavelength of 163n.
Since it has an absorber centering on m, it has a wavelength of 155 to 18
When used as an optical member of an optical device using 0 nm light as a light source, the hydrogen molecule content in the synthetic quartz glass is 1 ×.
It is preferably 10 17 molecule / cm 3 or less. It should be noted that it may be preferable to set the content of hydrogen molecules in the synthetic quartz glass to 1 × 10 17 molecules / cm 3 or less, depending on the use and the use conditions.
【0037】また、本発明の光学部材用合成石英ガラス
は、光学部材としての使用領域において、波長157.
6nmにおける内部光透過率が80%/cm以上である
ことが好ましく、特には、90%/cm以上、さらに
は、95%/cm以上である。Further, the synthetic quartz glass for an optical member of the present invention has a wavelength of 157.
The internal light transmittance at 6 nm is preferably 80% / cm or more, particularly 90% / cm or more, and further 95% / cm or more.
【0038】また、本発明の光学部材用合成石英ガラス
は、光学部材としての使用領域において、波長633n
mにおける屈折率均質性が100ppm以下であること
が好ましく、20ppm以下であることがより好まし
く、特には、10ppm以下、さらには、2ppm以下
である。The synthetic quartz glass for optical members of the present invention has a wavelength of 633n in the range of use as an optical member.
The refractive index homogeneity in m is preferably 100 ppm or less, more preferably 20 ppm or less, particularly 10 ppm or less, and further 2 ppm or less.
【0039】また、本発明の光学部材用合成石英ガラス
は、光学部材としての使用領域において、温度100℃
における熱膨張係数の最大と最小との差が200×10
−6/K以下であることが好ましく、40×10−6/
K以下であることがより好ましく、特には、20×10
−6/K以下、さらには、4×10−6/K以下であ
る。Further, the synthetic quartz glass for optical members of the present invention has a temperature of 100 ° C. in the usage region as an optical member.
The difference between the maximum and minimum thermal expansion coefficient in
It is preferably −6 / K or less, and 40 × 10 −6 /
It is more preferably K or less, and particularly 20 × 10
It is −6 / K or less, and further 4 × 10 −6 / K or less.
【0040】[0040]
【実施例】表1に示す条件にて、四塩化ケイ素またはヘ
キサメチルジシロキサン(HMDS)のガラス形成原料
を酸水素火炎中で加水分解させ、形成されたSiO2微
粒子を回転する基材上に堆積させて直径300mm、長
さ600mmの多孔質石英ガラスを作製した(工程
(a))。EXAMPLES Under the conditions shown in Table 1, a glass forming raw material of silicon tetrachloride or hexamethyldisiloxane (HMDS) was hydrolyzed in an oxyhydrogen flame, and the formed SiO 2 fine particles were formed on a rotating substrate. By depositing, a porous quartz glass having a diameter of 300 mm and a length of 600 mm was produced (step (a)).
【0041】続いて、多孔質石英ガラスを基体を介して
昇降機に固設して、あらかじめ表1に示す温度に保持さ
れている電気炉内に多孔質石英ガラスを0.1m/分の
速度で上昇・導入し、表1に示す時間保持することによ
り、多孔質石英ガラスの平均かさ密度、かさ密度分布を
調整した(工程(e))。Then, the porous quartz glass was fixed to the elevator through the substrate, and the porous quartz glass was placed in an electric furnace previously maintained at the temperature shown in Table 1 at a speed of 0.1 m / min. The average bulk density and bulk density distribution of the porous quartz glass were adjusted by raising and introducing and holding for the time shown in Table 1 (step (e)).
【0042】ここで多孔質石英ガラスの長手方向中央部
付近から厚み100mmを切断し、外周20mmを除く
領域内にて切断面の硬度を直径方向に10mm間隔にて
硬度計にて計30点測定することにより、多孔質石英ガ
ラスのかさ密度を評価した。平均かさ密度は計30点の
かさ密度の平均値とし、かさ密度分布は計30点の最大
かさ密度と最低かさ密度の差とした。また測定した硬度
からかさ密度を求める際には、別途、あらかじめ種々の
かさ密度の異なる多孔質石英ガラスを用いて硬度とかさ
密度の関係式を求めておき、この関係式を用いた。図1
に例1、例4、例10、例12のかさ密度分布の測定結
果を示す。Here, a thickness of 100 mm was cut from the vicinity of the central portion in the longitudinal direction of the porous quartz glass, and the hardness of the cut surface was measured at 10 mm intervals in the diametrical direction at a total of 30 points with a hardness meter in a region excluding the outer circumference of 20 mm. By doing so, the bulk density of the porous quartz glass was evaluated. The average bulk density was the average value of the bulk density of 30 points in total, and the bulk density distribution was the difference between the maximum bulk density and the minimum bulk density of 30 points in total. Further, when obtaining the bulk density from the measured hardness, the relational expression between the hardness and the bulk density was previously obtained by using various porous quartz glasses having different bulk densities, and this relational expression was used. Figure 1
The measurement results of the bulk density distributions of Example 1, Example 4, Example 10, and Example 12 are shown in FIG.
【0043】次いで、同電気炉から多孔質石英ガラスを
取り出し、多孔質石英ガラスを室温になるまで冷却した
後、作製した多孔質石英ガラスを雰囲気制御可能な炉に
セットし、表1に示す条件にてOH基含有量低減処理と
フッ素ドープ処理とを実施した(工程(b)および工程
(c))。Next, the porous quartz glass was taken out from the electric furnace, cooled to room temperature, and the prepared porous quartz glass was set in a furnace in which the atmosphere could be controlled under the conditions shown in Table 1. The OH group content reduction treatment and the fluorine doping treatment were carried out at (step (b) and step (c)).
【0044】その後、多孔質石英ガラスを圧力100P
a以下の減圧に保持した状態で1450℃まで昇温し
て、この温度にて10時間保持し透明石英ガラス体を作
製した(工程(d))。After that, the porous quartz glass is pressured to 100 P.
While maintaining a reduced pressure of a or less, the temperature was raised to 1450 ° C. and maintained at this temperature for 10 hours to produce a transparent quartz glass body (step (d)).
【0045】各例で得られた透明石英ガラス体を内径2
40mmのカーボン製るつぼの中にセットし、同るつぼ
を電気炉内でアルゴンガス、100vol%、1atm
にて1750℃まで昇温して、この温度にて10時間保
持することにより、透明石英ガラス体の成形を行った。The inner diameter of the transparent quartz glass body obtained in each example was 2
Set in a 40 mm carbon crucible, and place the crucible in an electric furnace with argon gas, 100 vol%, 1 atm.
The transparent quartz glass body was molded by raising the temperature to 1750 ° C. and holding at this temperature for 10 hours.
【0046】次いで、得られた透明石英ガラス体の長手
方向ほぼ中央からサイズφ150mm×20mm厚の評
価用試料を切出し、表面の平坦度が5μm以下となるよ
うに#1000の研削盤にて研削を実施し、以下の評価
を行った。Then, an evaluation sample having a size of φ150 mm × 20 mm was cut out from approximately the center in the longitudinal direction of the obtained transparent quartz glass body, and ground with a # 1000 grinder so that the surface flatness was 5 μm or less. It carried out and evaluated the following.
【0047】(OH基含有量評価)評価用試料の中央付
近について赤外分光光度計による測定を行い、波長2.
7μmにおける吸収ピークからOH基含有量を求めた
(J.P.Wiliamset.al.,Cerami
c Bulletin, 55(5), 524,19
76)。本法による検出限界は1ppmである。(Evaluation of OH group content) Measurement was carried out by an infrared spectrophotometer in the vicinity of the center of the sample for evaluation to obtain a wavelength of 2.
The OH group content was determined from the absorption peak at 7 μm (JP Williams et al., Cerami.
c Bulletin, 55 (5), 524, 19
76). The detection limit of this method is 1 ppm.
【0048】(フッ素含有量評価およびその分布評価)
評価用試料の直径方向に10mm間隔で計30点のフッ
素含有量をフッ素イオン電極法により分析した。ここ
で、測定した計30点のフッ素含有量の平均値を平均フ
ッ素含有量とし、最大フッ素含有量と最小フッ素含有量
の差をフッ素含有量分布とした。なおフッ素含有量の分
析方法は下記の通りである。日本化学会誌、1972(2), 3
50に記載された方法に従って、合成石英ガラスを無水炭
酸ナトリウムにより加熱融解し、得られた融液に蒸留水
および塩酸(体積比で1:1)を加えて試料液を調整し
た。試料液の起電力をフッ素イオン選択性電極および比
較電極としてラジオメータトレーディング社製No.9
45−220およびNo.945−468をそれぞれ用
いてラジオメータにより測定し、フッ素イオン標準溶液
を用いてあらかじめ作成した検量線に基づいて、フッ素
含有量を求めた。本法による検出限界は10ppmであ
る。(Evaluation of fluorine content and distribution thereof)
The fluorine content of 30 points in total in the diameter direction of the evaluation sample was analyzed by the fluorine ion electrode method at intervals of 10 mm. Here, the average value of the measured fluorine content of 30 points in total was defined as the average fluorine content, and the difference between the maximum fluorine content and the minimum fluorine content was defined as the fluorine content distribution. The method for analyzing the fluorine content is as follows. Journal of the Chemical Society of Japan, 1972 (2), 3
According to the method described in 50, the synthetic quartz glass was heated and melted with anhydrous sodium carbonate, and distilled water and hydrochloric acid (volume ratio 1: 1) were added to the obtained melt to prepare a sample liquid. The electromotive force of the sample liquid was changed to No. 9
45-220 and No. 45-220. 945-468 was used for each measurement with a radiometer, and the fluorine content was determined based on a calibration curve prepared in advance using a fluorine ion standard solution. The detection limit of this method is 10 ppm.
【0049】(波長157.6nmでの内部光透過率評
価)評価用試料の中央より20mm×20mm×5mm
の試料、および20mm×20mm×30mmの試料を
切り出し、それぞれ20mm角の2面を鏡面研磨し、試
料の温度を25℃に保持した状態で真空紫外分光光度計
(分光計器社製UV201M)により波長157.6n
mでの光透過率を窒素雰囲気下にて測定した。厚み5m
mおよび厚み30mmの2種類の試料の波長157.6
nm光透過率T1、T2より、波長163nmにおける
内部光透過率T157.6を下記の式(1)に従って求
めた。(Evaluation of Internal Light Transmittance at Wavelength 157.6 nm) 20 mm × 20 mm × 5 mm from the center of the sample for evaluation
And a sample of 20 mm × 20 mm × 30 mm are cut out, two 20 mm square surfaces are mirror-polished, and the wavelength is measured by a vacuum ultraviolet spectrophotometer (UV201M manufactured by Spectrometer Co., Ltd.) with the sample temperature kept at 25 ° C. 157.6n
The light transmittance at m was measured under a nitrogen atmosphere. 5m thickness
m and thickness of 30 mm for two types of samples having a wavelength of 157.6
The internal light transmittance T 157.6 at a wavelength of 163 nm was calculated from the nm light transmittances T 1 and T 2 according to the following formula (1).
【0050】[0050]
【数1】 [Equation 1]
【0051】(屈折率均質性評価)フィゾー干渉計にて、
オイルオンプレート法で、評価用試料の240mmφの
面にヘリウムネオンレーザ光(波長633nm)を垂直
にあて、中央200mmφの面内での屈折率分布を測定
し、屈折率の最大と最小との差を屈折率均質性とした。(Evaluation of homogeneity of refractive index) With a Fizeau interferometer,
With the oil-on-plate method, the helium neon laser light (wavelength 633 nm) was perpendicularly applied to the 240 mmφ surface of the evaluation sample, and the refractive index distribution in the center 200 mmφ surface was measured to find the difference between the maximum and minimum refractive indexes. Was defined as the refractive index homogeneity.
【0052】(熱膨張係数分布の評価)評価用試料の直
径方向に50mm間隔にて、レーザ熱膨張計(真空理工
製LIX−1型)により、温度100度における熱膨張
係数αを測定し、その最大と最小との差を熱膨張係数分
布とした。(Evaluation of Thermal Expansion Coefficient Distribution) The thermal expansion coefficient α at a temperature of 100 ° C. was measured with a laser thermal expansion meter (LIX-1 manufactured by Vacuum Riko) at 50 mm intervals in the diameter direction of the evaluation sample. The difference between the maximum and the minimum was defined as the thermal expansion coefficient distribution.
【0053】各評価の結果を表2に示す。なお例9、例
12、例13および例16〜例18は比較例、その他は
実施例である。また、例1、4、10、12について、
かさ密度分布のグラフを図示したのが図1である。The results of each evaluation are shown in Table 2. Note that Examples 9, 12, 13 and 16 to 18 are comparative examples, and the others are examples. Also, for Examples 1, 4, 10, and 12,
FIG. 1 shows a graph of the bulk density distribution.
【0054】[0054]
【表1】 [Table 1]
【0055】[0055]
【表2】 [Table 2]
【0056】[0056]
【発明の効果】本発明によれば、本発明は、フッ素含有
量の均一性に優れたフッ素含有合成石英ガラスを安定し
て作製する方法ならびに、屈折率均質性、耐光性および
光透過性に優れたフッ素含有合成石英ガラスが得られ
る。EFFECTS OF THE INVENTION According to the present invention, the present invention provides a method for stably producing a fluorine-containing synthetic quartz glass excellent in the uniformity of the fluorine content, as well as the refractive index homogeneity, light resistance and light transmission. An excellent fluorine-containing synthetic quartz glass is obtained.
【図1】かさ密度分布のグラフFig. 1 Graph of bulk density distribution
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 FI テーマコート゛(参考) G02B 1/00 G02B 1/00 ─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. 7 Identification Code FI Theme Coat (Reference) G02B 1/00 G02B 1/00
Claims (9)
光学装置の光学部材として用いられる光学部材用合成石
英ガラスの製造方法において、(a)ガラス形成原料を
火炎加水分解して得られる石英ガラス微粒子を基材に堆
積・成長させて多孔質石英ガラスを形成する工程と、
(b)該多孔質石英ガラスのOH基含有量を低減する工
程と、(c)該多孔質石英ガラスをフッ素化合物含有雰
囲気下に保持し、該多孔質石英ガラスにフッ素をドープ
する工程と、(d)該多孔質石英ガラスを1300℃以
上の温度に昇温して透明ガラス化し、フッ素を含有した
透明石英ガラス体を得る工程と、を含み、 工程(b)における多孔質石英ガラスの平均かさ密度が
1.6g/cm3以下、かつ多孔質石英ガラスの成長軸
方向に垂直な断面において、外周から20mmを除いた
領域内でのかさ密度の最大と最小の差がかさ密度の最大
と最小との差が0.6g/cm3以下であることを特徴
とする光学部材用合成石英ガラスの製造方法。1. A method for producing synthetic quartz glass for an optical member used as an optical member of an optical device having a light source having a wavelength of 155 to 250 nm as a light source, wherein (a) a quartz glass obtained by flame hydrolysis of a glass forming raw material. A step of depositing and growing fine particles on a base material to form a porous quartz glass;
(B) a step of reducing the OH group content of the porous quartz glass, and (c) a step of holding the porous quartz glass in a fluorine compound-containing atmosphere and doping the porous quartz glass with fluorine. (D) a step of raising the temperature of the porous quartz glass to a temperature of 1300 ° C. or higher to obtain a transparent quartz glass body containing fluorine to obtain a transparent quartz glass body containing fluorine, and the average of the porous quartz glass in the step (b). In the cross section of the bulk silica glass having a bulk density of 1.6 g / cm 3 or less and perpendicular to the growth axis direction of the porous quartz glass, the difference between the maximum and minimum bulk densities within the region excluding 20 mm from the outer circumference is the maximum bulk density. A method for producing synthetic quartz glass for optical members, characterized in that the difference from the minimum is 0.6 g / cm 3 or less.
石英ガラスをフッ素化合物含有雰囲気下に保持し、多孔
質石英ガラスをフッ素ドープさせると同時にOH基含有
量を低減することにより行う請求項1記載の光学部材用
合成石英ガラスの製造方法。1記載の光学部材用合成石
英ガラスの製造方法。2. The steps (b) and (c) are carried out by keeping the porous quartz glass in a fluorine compound-containing atmosphere to dope the porous quartz glass with fluorine and at the same time reduce the OH group content. The method for producing synthetic quartz glass for an optical member according to claim 1, which is performed. 1. The method for producing the synthetic quartz glass for an optical member according to 1.
スを1000℃〜1500℃の範囲内に加熱することに
より、該多孔質石英ガラスの平均かさ密度を調整する工
程、を含む請求項1または2記載の光学部材用合成石英
ガラスの製造方法。3. After the step (a), there is included (e) a step of heating the porous quartz glass in the range of 1000 ° C. to 1500 ° C. to adjust the average bulk density of the porous quartz glass. A method for producing the synthetic quartz glass for an optical member according to claim 1.
光学装置の光学部材として用いられる光学部材用合成石
英ガラスにおいて、光学部材としての使用領域における
フッ素含有量が50ppm以上、OH基含有量が10p
pm以下であり、かつフッ素含有量の最大と最小との差
が250ppm以下であることを特徴とする光学部材用
合成石英ガラス。4. A synthetic quartz glass for an optical member used as an optical member of an optical device having a light source having a wavelength of 155 to 250 nm as a light source, wherein a fluorine content in an area used as the optical member is 50 ppm or more and an OH group content is 10p
Synthetic quartz glass for optical members, which is pm or less and has a difference between the maximum and minimum fluorine contents of 250 ppm or less.
光学装置の光学部材として用いられる光学部材用合成石
英ガラスにおいて、光学部材としての使用領域における
フッ素含有量が50ppm以上、OH基含有量が1pp
m以下であり、かつフッ素含有量の最大と最小との差が
250ppm以下であることを特徴とする光学部材用合
成石英ガラス。5. A synthetic quartz glass for an optical member used as an optical member of an optical device having a light source having a wavelength of 155 to 180 nm as a light source, wherein a fluorine content in an area used as the optical member is 50 ppm or more and an OH group content is 1 pp
A synthetic quartz glass for an optical member, characterized in that it is m or less, and the difference between the maximum and minimum fluorine contents is 250 ppm or less.
光学装置の光学部材として用いられる光学部材用合成石
英ガラスにおいて、光学部材としての使用領域における
フッ素含有量が50ppm以上、OH基含有量が1pp
m以下であり、かつフッ素含有量の最大と最小との差が
50ppm以下であることを特徴とする光学部材用合成
石英ガラス。6. A synthetic quartz glass for an optical member used as an optical member of an optical device having a light source having a wavelength of 155 to 180 nm as a light source, wherein a fluorine content in an area used as the optical member is 50 ppm or more, and an OH group content is 1 pp
The synthetic quartz glass for optical members is characterized in that it is m or less and the difference between the maximum and minimum fluorine contents is 50 ppm or less.
157.6nmにおける内部光透過率が80%/cm以
上である請求項4〜6いずれか1項記載の光学部材用合
成石英ガラス。7. The synthetic quartz glass for an optical member according to claim 4, which has an internal light transmittance of 80% / cm or more at a wavelength of 157.6 nm in a region of use as an optical member.
633nmにおける屈折率の最大と最小の差が100p
pm以下である請求項4〜7いずれか1項記載の光学部
材用合成石英ガラス。8. The difference between the maximum and the minimum of the refractive index at a wavelength of 633 nm is 100 p in the usage area as an optical member.
The synthetic quartz glass for an optical member according to any one of claims 4 to 7, which has a pm or less.
100℃における熱膨張係数の最大と最小との差が20
0×10−6/K以下であることを特徴とする請求項4
〜8いずれか1項記載の光学部材用合成石英ガラス。9. A difference between the maximum and the minimum of the coefficient of thermal expansion at a temperature of 100 ° C. is 20 in the range of use as an optical member.
It is 0x10 < -6 > / K or less, Claim 4 characterized by the above-mentioned.
8. A synthetic quartz glass for an optical member according to any one of items 8 to 8.
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005179088A (en) * | 2003-12-17 | 2005-07-07 | Asahi Glass Co Ltd | Synthetic quartz glass for optical member and method of manufacturing the same |
JP2006242582A (en) * | 2005-02-28 | 2006-09-14 | Kyocera Kinseki Corp | Sorting method of optical quartz |
WO2008032698A1 (en) * | 2006-09-11 | 2008-03-20 | Tosoh Corporation | Fused quartz glass and process for producing the same |
EP2371773A1 (en) | 2010-04-01 | 2011-10-05 | Asahi Glass Company, Limited | Method for production of synthetic quartz glass |
EP2371772A1 (en) | 2010-04-01 | 2011-10-05 | Asahi Glass Company, Limited | Method for production of synthetic quartz glass |
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JP2001089170A (en) * | 1999-09-16 | 2001-04-03 | Shinetsu Quartz Prod Co Ltd | Optical silica glass member for f2 excimer laser transmission and method for producing the same |
JP2001151531A (en) * | 1999-11-24 | 2001-06-05 | Shinetsu Quartz Prod Co Ltd | Silica glass optical material for projection lens used to vacuum uv ray lighography, its manufacturing method and projection lens |
JP2001342034A (en) * | 2000-05-29 | 2001-12-11 | Shinetsu Quartz Prod Co Ltd | Optical material of synthetic quartz glass for f2 excimer laser and optical part |
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2001
- 2001-12-18 JP JP2001384424A patent/JP2003183034A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2001089170A (en) * | 1999-09-16 | 2001-04-03 | Shinetsu Quartz Prod Co Ltd | Optical silica glass member for f2 excimer laser transmission and method for producing the same |
JP2001151531A (en) * | 1999-11-24 | 2001-06-05 | Shinetsu Quartz Prod Co Ltd | Silica glass optical material for projection lens used to vacuum uv ray lighography, its manufacturing method and projection lens |
JP2001342034A (en) * | 2000-05-29 | 2001-12-11 | Shinetsu Quartz Prod Co Ltd | Optical material of synthetic quartz glass for f2 excimer laser and optical part |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005179088A (en) * | 2003-12-17 | 2005-07-07 | Asahi Glass Co Ltd | Synthetic quartz glass for optical member and method of manufacturing the same |
JP2006242582A (en) * | 2005-02-28 | 2006-09-14 | Kyocera Kinseki Corp | Sorting method of optical quartz |
WO2008032698A1 (en) * | 2006-09-11 | 2008-03-20 | Tosoh Corporation | Fused quartz glass and process for producing the same |
EP2070883A1 (en) * | 2006-09-11 | 2009-06-17 | Tosoh Corporation | Fused quartz glass and process for producing the same |
US8211817B2 (en) | 2006-09-11 | 2012-07-03 | Tosoh Corporation | Fused silica glass and process for producing the same |
EP2070883A4 (en) * | 2006-09-11 | 2012-09-12 | Tosoh Corp | Fused quartz glass and process for producing the same |
EP2371773A1 (en) | 2010-04-01 | 2011-10-05 | Asahi Glass Company, Limited | Method for production of synthetic quartz glass |
EP2371772A1 (en) | 2010-04-01 | 2011-10-05 | Asahi Glass Company, Limited | Method for production of synthetic quartz glass |
JP2016011252A (en) * | 2010-04-01 | 2016-01-21 | 旭硝子株式会社 | Optical member |
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