JPH0616449A - Synthetic quartz glass optical member for excimer laser and its production - Google Patents
Synthetic quartz glass optical member for excimer laser and its productionInfo
- Publication number
- JPH0616449A JPH0616449A JP4210622A JP21062292A JPH0616449A JP H0616449 A JPH0616449 A JP H0616449A JP 4210622 A JP4210622 A JP 4210622A JP 21062292 A JP21062292 A JP 21062292A JP H0616449 A JPH0616449 A JP H0616449A
- Authority
- JP
- Japan
- Prior art keywords
- quartz glass
- synthetic quartz
- excimer laser
- optical member
- synthetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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
- C03B2201/06—Doped silica-based glasses
- C03B2201/07—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
- C03B2201/07—Impurity concentration specified
- C03B2201/075—Hydroxyl ion (OH)
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/21—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with molecular hydrogen
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/08—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
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
- C03C2201/23—Doped silica-based glasses containing non-metals other than boron or halide containing hydroxyl groups
-
- 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
-
- 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)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Glass Compositions (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、発振波長300nm以
下の紫外レーザー光の照射に対して優れた安定性を有す
る光学用石英ガラス部材及びその製造方法に関し、特
に、KrF,ArFエキシマレーザーの照射に対して優
れた安定性を有する合成石英ガラス製の光学部材及びそ
の製造方法に関する。また、本発明は、半導体チップ製
造用の、特にエキシマレーザーを光源とするリソグラフ
ィ装置の光学系を構成する窓、鏡、レンズ及びプリズム
等の光学部材に好適に使用される石英ガラス部材の製造
方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical quartz glass member having excellent stability against irradiation with an ultraviolet laser beam having an oscillation wavelength of 300 nm or less and a method for producing the same, and particularly to irradiation with a KrF or ArF excimer laser. The present invention relates to an optical member made of synthetic quartz glass having excellent stability with respect to the above and a manufacturing method thereof. Further, the present invention is a method for manufacturing a quartz glass member, which is preferably used for optical members such as windows, mirrors, lenses and prisms, which constitute an optical system of a lithographic apparatus using an excimer laser as a light source, for manufacturing a semiconductor chip. It is about.
【0002】[0002]
【従来の技術】近年、LSIの高集積化に伴い、ウエハ
上に集積回路パターンを描画する光リソグラフィー技
術、即ちリソグラフィ技術においては、例えばサブミク
ロン単位の極めて微細な線幅の線による正確な像の描画
技術が要求されてきている。そこで光リソグラフィ技術
においては、このような極めて微細な線幅の線により正
確な像の描画を行うために、露光系の光源の光の波長を
短波にすることが進められている。例えば、リソグラフ
ィ用のステッパーレンズは、ウエハ上に、濃淡のない微
細な線幅の線により、集積回路パターンの歪まない正確
な像を明確に映し出すために、紫外線に対する優れた透
過性、紫外線、特に紫外レーザー光に対する屈折率分布
の均質性及び紫外レーザー光の照射に対して強い耐久性
が要求されている。2. Description of the Related Art In recent years, with the high integration of LSIs, in an optical lithography technique for drawing an integrated circuit pattern on a wafer, that is, a lithography technique, for example, an accurate image is formed by a line having an extremely fine line width of submicron unit. Drawing technology has been required. Therefore, in the photolithography technology, in order to accurately draw an image with such a line having an extremely fine line width, the wavelength of the light of the light source of the exposure system is being shortened. For example, a stepper lens for lithography has excellent transparency to ultraviolet rays, especially ultraviolet rays, in order to clearly and accurately display an undistorted, accurate image of an integrated circuit pattern on a wafer with fine line widths without light and shade. The homogeneity of the refractive index distribution with respect to the ultraviolet laser light and the strong durability against the irradiation with the ultraviolet laser light are required.
【0003】ところが、従来の一般的な光学ガラスを用
いたレンズは、紫外線の通過性が極めて悪く、例えば、
365nm(i線)より短い波長領域の紫外線を使用す
る場合には、使用中に紫外線の透過率が急激に減少し
て、ステッパーレンズとして使用することが実質的に困
難であった。殊に、365nm(i線)より短い波長領
域の紫外線を使用する場合には、紫外線の吸収によりレ
ンズが発熱して、光学ガラスの光学的特性が変化し、レ
ンズの焦点距離を狂わせる要因となっている。このよう
なことから、紫外線透過材料として、石英ガラスが用い
られてきた。しかしながら、天然の水晶から製造された
石英ガラスは、250nm以下の波長領域の紫外線に対
し光透過性が悪く、その上、紫外線の照射により、紫外
線領域に新たに光の吸収を生じて、紫外線の透過率が更
に低下するので、ステッパーレンズとして使用すること
が実質的に困難であった。この天然水晶により製造され
た石英ガラスにおける紫外線領域における光の吸収は、
石英ガラス中の不純物に起因すると考えられるために、
紫外線領域で使用される光学部材には、不純物含有量の
少ない合成石英ガラス、即ち合成シリカガラスが使用さ
れている。However, a conventional lens using general optical glass has a very poor ultraviolet ray passing property, and for example,
When ultraviolet rays having a wavelength range shorter than 365 nm (i-line) are used, the transmittance of ultraviolet rays sharply decreases during use, and it is practically difficult to use as a stepper lens. In particular, when ultraviolet rays in the wavelength range shorter than 365 nm (i-line) are used, the lens heats up due to the absorption of ultraviolet rays, and the optical characteristics of the optical glass change, which causes the focal length of the lens to change. ing. For this reason, quartz glass has been used as an ultraviolet transmitting material. However, quartz glass manufactured from natural quartz has poor optical transparency to ultraviolet rays in the wavelength range of 250 nm or less, and furthermore, the irradiation of ultraviolet rays causes a new absorption of light in the ultraviolet ray area, and Since the transmittance is further reduced, it is practically difficult to use as a stepper lens. Absorption of light in the ultraviolet region in the quartz glass produced by this natural quartz,
Because it is thought that it is due to impurities in the quartz glass,
Synthetic quartz glass having a low content of impurities, that is, synthetic silica glass is used for optical members used in the ultraviolet region.
【0004】この合成石英ガラスは、通常、紫外線吸収
の原因となる金属不純物の混入を避けるために、化学的
に合成され、蒸留により精製された、高純度の揮発性の
珪素化合物、一般的には、例えば四塩化珪素(SiCl
4)等のハロゲン化珪素、例えばエトキシシラン(Si
(OC2H5)4)、メトキシシラン(Si(OC
H3)4)等のアルコキシシラン類、さらに例えばメチ
ルトリメトキシシラン(SiCH3(OCH3)3)、
エチルトリエトキシシラン(SiC2H5(OC
2H5)3)等のアルキルアルコキシシラン類の蒸気
を、直接酸水素炎中に導入して、酸水素炎により火炎加
水分解させ、ここで分解生成したガラス微粒子を、直接
回転する耐熱性棒状芯部材上に溶融堆積させてガラス化
させることにより、透明なガラスに製造されている。ま
た上記ガラス微粒子を耐熱性棒状芯部材上に堆積させて
多孔質ガラスを作り、それを電気炉中で加熱溶融して透
明なガラスに製造することもできる。This synthetic quartz glass is usually a high-purity volatile silicon compound, which is chemically synthesized and purified by distillation, in order to avoid the inclusion of metallic impurities that cause ultraviolet absorption, generally. Is, for example, silicon tetrachloride (SiCl
4 ) silicon halide such as ethoxysilane (Si
(OC 2 H 5 ) 4 ), methoxysilane (Si (OC
H 3) 4) alkoxysilanes such as, further such as methyl trimethoxy silane (SiCH 3 (OCH 3) 3 ),
Ethyltriethoxysilane (SiC 2 H 5 (OC
The vapor of alkylalkoxysilanes such as 2 H 5 ) 3 ) is directly introduced into an oxyhydrogen flame and flame hydrolyzed by the oxyhydrogen flame, and the glass particles decomposed and produced here are directly rotated into a heat-resistant rod shape. It is manufactured into transparent glass by melting and depositing it on the core member and vitrifying it. It is also possible to deposit the above glass fine particles on a heat-resistant rod-shaped core member to prepare porous glass, and heat and melt it in an electric furnace to produce transparent glass.
【0005】このようにして製造された透明な合成石英
ガラスは、極めて高純度で、金属不純物を殆ど含んでお
らず、また、190nm程度の短波長領域まで良好な光
透過性を示すので、紫外レーザー光、例えば具体的には
前記i線の他に、KrF(248nm),XeCl(3
08nm),XeBr(282nm),XeF(35
1、353nm),ArF(193nm)等のエキシマ
レーザー光及びYAGの4倍高調波(250nm)等に
ついての透過材料として使用されている。例えば、原料
の四塩化珪素を一層高純度にすると共に、酸水素炎によ
る火炎加水分解の条件を調節することによって、金属不
純物元素含有率が、0.1ppm以下で、所定濃度のO
H基を含有させた高純度石英ガラスを合成し、これによ
り紫外レーザー光に対する耐久性を改善した光学用の石
英ガラス部材を製造する試みがなされている(特開平1
−167258号公報)。The transparent synthetic quartz glass produced in this manner is extremely high in purity, contains almost no metal impurities, and exhibits good light transmittance up to a short wavelength region of about 190 nm. Laser light, such as KrF (248 nm), XeCl (3
08 nm), XeBr (282 nm), XeF (35
1, 353 nm), ArF (193 nm) and other excimer laser lights, and YAG fourth harmonics (250 nm) and the like are used as transmission materials. For example, by increasing the purity of silicon tetrachloride as a raw material and adjusting the conditions of flame hydrolysis by an oxyhydrogen flame, the content of metal impurity elements is 0.1 ppm or less, and the content of O of a predetermined concentration is reduced.
Attempts have been made to synthesize a high-purity quartz glass containing an H group, and thereby to manufacture an optical quartz glass member having improved durability against ultraviolet laser light (Japanese Patent Application Laid-Open No. HEI-1).
No. 167258).
【0006】しかし、これらの方法により製造された光
学用の石英ガラス部材は、紫外レーザー光に対して、耐
久性に優れてはいるが、製造工程の工程数を増加するこ
ととなって、技術的にも、時間的にも、また経済的にも
問題がある。ところで、合成石英ガラスにおいても紫外
線を照射したとき、新たに紫外線領域に光の吸収帯を生
じる。この合成石英ガラスにおける紫外線領域の新たな
光の吸収帯は、専ら、石英ガラス中の、例えば、SiO
HやSiCl等のSiO2以外の構造、或いは、Si−
Si、Si−O−O−Si等の酸素欠損又は酸素過剰構
造による固有欠陥が、光反応によって、常磁性欠陥を生
じることにより生成すると考えられている。合成石英ガ
ラスにおけるこのような常磁性欠陥による光吸収として
は、例えば、E’センター(Si・)やNBOHC(S
i−O・)などが、これまでESRスペクトルなどで数
多く同定されている。However, although the quartz glass member for optics manufactured by these methods is excellent in durability against ultraviolet laser light, the number of manufacturing steps increases, which is a technical problem. There are problems in terms of time, time, and economy. By the way, when synthetic quartz glass is also irradiated with ultraviolet rays, a new absorption band of light is generated in the ultraviolet region. The new absorption band of light in the ultraviolet region in this synthetic quartz glass is, for example, SiO in the quartz glass.
Structures other than SiO 2 , such as H and SiCl, or Si-
It is believed that intrinsic defects due to oxygen deficiency or oxygen excess structure such as Si and Si-O-O-Si are generated by causing paramagnetic defects by photoreaction. Light absorption due to such paramagnetic defects in synthetic quartz glass includes, for example, E'center (Si.) And NBOHC (S).
i-O.) and the like have been identified so far in ESR spectra and the like.
【0007】以上のように、常磁性欠陥は、一般的に
は、光学的吸収帯を有している。したがって、石英ガラ
スに紫外線を照射した場合、石英ガラスの常磁性欠陥に
よる紫外線領域で問題となる吸収帯としては、例えば、
E’センターの215nmと、まだ正確に同定されてい
ないが、260nmがある。これらの吸収帯は比較的ブ
ロードでかつ、強い吸収を生じ、例えば、ArFレーザ
ー(193nm)やKrFレーザー(248nm)の透
過材料として用いる場合に、大きな問題となっている。
このような理由から、エキシマレーザーに使用される合
成石英ガラスは、強い紫外線、例えば紫外レーザー光が
照射されても、例えば新しい吸収帯を生じることなどの
ない、より強い紫外線耐久性が要求される。本発明は、
エキシマレーザーに代表される紫外レーザーを光源とす
る光学系に使用される光学用石英ガラス部材において、
かかる紫外線照射により生じる透過率低下の問題を解決
することを目的としている。As described above, the paramagnetic defect generally has an optical absorption band. Therefore, when the quartz glass is irradiated with ultraviolet rays, as the absorption band which becomes a problem in the ultraviolet region due to the paramagnetic defect of the quartz glass, for example,
The E'center is 215 nm, which is 260 nm although it has not been accurately identified. These absorption bands are relatively broad and generate strong absorption, which is a serious problem when used as a transmissive material for ArF lasers (193 nm) and KrF lasers (248 nm), for example.
For this reason, the synthetic quartz glass used in the excimer laser is required to have higher UV durability, which does not cause a new absorption band, for example, even when it is irradiated with strong UV rays, such as UV laser light. . The present invention is
In an optical quartz glass member used in an optical system using an ultraviolet laser represented by an excimer laser as a light source,
It is intended to solve the problem of the decrease in transmittance caused by such ultraviolet irradiation.
【0008】[0008]
【課題を解決するための手段】本発明者らは、上記の課
題を解決するために、鋭意研究の結果、合成石英ガラス
中の固有欠陥と結び付く不純物として、水酸基(OH
基)及び塩素があることを見い出し、合成石英ガラスに
おけるOH基含有率を10乃至100ppmに低減さ
せ、また合成石英ガラスにおける塩素含有率を200p
pm以下に低減させることにより、また、Δnで5×1
0−6以下の屈折率分布の均質性及び5nm/cm以下
の複屈折を有することにより、耐エキシマレーザー性の
優れた石英ガラスが得られることを見いだし、本発明に
到達したものである。本発明は、エキシマレーザーに光
学部材として使用される合成石英ガラスにおいて、エキ
シマレーザー光の照射に伴って生じる紫外線領域におけ
る光透過率の低下を極力低減した合成石英ガラス及びそ
の製造方法を提供するものであり、特に、エキシマレー
ザー用のステッパーレンズに好適に使用しうる光学用石
英ガラス部材及びその製造方法を提供するものである。In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive studies and as a result, as a result of the fact that hydroxyl groups (OH
Group) and chlorine to reduce the OH group content in the synthetic quartz glass to 10 to 100 ppm, and the chlorine content in the synthetic quartz glass to 200 p
By reducing to pm or less, Δn is 5 × 1
By 0 -6 to have homogeneity and 5 nm / cm or less in birefringence of the following refractive index profile, found that resistance to excimer laser with excellent quartz glass is obtained, in which have reached the present invention. The present invention provides a synthetic quartz glass used as an optical member for an excimer laser, in which a decrease in light transmittance in an ultraviolet region caused by irradiation of excimer laser light is reduced as much as possible, and a method for producing the same. In particular, the present invention provides an optical quartz glass member that can be suitably used for a stepper lens for an excimer laser, and a method for producing the same.
【0009】即ち、本発明は、合成石英ガラス製のエキ
シマレーザー用光学部材において、10乃至100pp
mのOH基の含有率、200ppm以下の塩素の含有
率、1×1016分子数/cm3以下の水素分子含有
率、Δnで5×10−6以下の屈折率分布の均質性及び
5nm/cm以下の複屈折を有することを特徴とする合
成石英ガラス製のエキシマレーザー用光学部材にあり、
また、本発明は、揮発性けい素化合物を、酸水素炎によ
り火炎加水分解し、生成する微粒子シリカを耐熱性基体
上に堆積させて多孔質シリカ母材を製造し、該多孔質シ
リカ母材を1×10−2トール以上の高真空度下で14
00℃以上の温度に加熱して、脱水及び脱ガスしてガラ
ス化を行い、次いで、この脱水及び脱ガスされた透明な
石英ガラスを均質化処理することにより、少なくとも一
方向に脈理を有しない高均質石英ガラスを形成し、次い
でこの得られた該高均質石英ガラスを成形し、成形され
た高均質石英ガラスをアニール処理することを特徴とす
る、10乃至200ppmのOH基の含有率、好ましく
は10乃至100ppmのOH基の含有率、200pp
m以下の塩素の含有率、1×1016分子数/cm3以
下の水素分子含有率、Δnで5×10−6以下の屈折率
分布の均質性及び5nm/cm以下の複屈折を有する合
成石英ガラス製のエキシマレーザー用光学部材の製造方
法にある。That is, the present invention relates to an optical member for excimer laser made of synthetic quartz glass, which is 10 to 100 pp.
OH group content of m, chlorine content of 200 ppm or less, hydrogen molecule content of 1 × 10 16 molecules / cm 3 or less, homogeneity of refractive index distribution of 5 × 10 −6 or less in Δn and 5 nm / An excimer laser optical member made of synthetic silica glass, which has a birefringence of not more than cm.
Further, the present invention is to produce a porous silica matrix by subjecting a volatile silicon compound to flame hydrolysis by an oxyhydrogen flame and depositing the resulting fine particle silica on a heat-resistant substrate to produce the porous silica matrix. At a high vacuum of 1 × 10 −2 Torr or higher.
By heating to a temperature of 00 ° C. or higher, dehydration and degassing, vitrification is performed, and then the dehydrated and degassed transparent quartz glass is homogenized to have striae in at least one direction. Forming a high-homogeneous quartz glass which is not formed, then shaping the obtained high-homogeneous quartz glass, and annealing the shaped high-homogeneous quartz glass, the content of OH group of 10 to 200 ppm, OH group content of preferably 10 to 100 ppm, 200 pp
Synthesis with chlorine content of m or less, hydrogen molecule content of 1 × 10 16 molecules / cm 3 or less, homogeneity of refractive index distribution of 5 × 10 −6 or less in Δn, and birefringence of 5 nm / cm or less A method of manufacturing an optical member for excimer laser made of quartz glass.
【0010】本発明者らは、前記光学部材を構成する合
成石英ガラスにおいて、波長245nmにおける光の内
部透過率が99%以上である場合、エキシマレーザー光
の照射に対してより安定性が向上することを見いだし
た。一般に245nmの吸収帯は酸素欠損による吸収と
言われており、この吸収がない光学部材がエキシマレー
ザー用光学部材を構成する上で好ましいことが分かっ
た。The inventors of the present invention have further improved stability against irradiation of excimer laser light when the synthetic quartz glass constituting the optical member has an internal transmittance of light at a wavelength of 245 nm of 99% or more. I found a thing. It is generally said that the absorption band at 245 nm is absorption due to oxygen deficiency, and it has been found that an optical member without this absorption is preferable in constructing an optical member for excimer laser.
【0011】本発明者らは、合成石英ガラス中のOH基
含有率及び塩素含有率は、少なければ少ないほど(例え
ば、両者共に5ppm以下)エキシマレーザーに対する
耐久性の点で好ましいが、合成石英ガラス成形体におい
て、OH基の含有率が10乃至100ppm、また塩素
の含有率が200ppm以下であれば、エキシマレーザ
ーにおいて、良好な透過率安定性が得られることを見い
出した。殊に、固有欠損による光吸収に係るOH基の含
有率については、10乃至200ppmのOH基の含有
率であれば、エキシマレーザーに対する耐久性の上で許
容できることを発見した。しかし、長時間の使用に亙っ
て固有欠損による光吸収が現れずに、長時間に亙り良好
な屈折率の均質性及び複屈折を保ち、より安定したエキ
シマレーザー光用の光学部材とするには、OH基の含有
率は10乃至100ppmであるのが好ましい。The inventors have found that the smaller the OH group content and the chlorine content in the synthetic quartz glass, the better (eg, both are 5 ppm or less) in terms of durability against excimer laser. It has been found that when the content of OH groups in the molded product is 10 to 100 ppm and the content of chlorine is 200 ppm or less, good transmittance stability can be obtained in the excimer laser. In particular, regarding the content of OH groups related to light absorption due to intrinsic defects, it has been discovered that the content of OH groups of 10 to 200 ppm is acceptable in terms of durability against excimer laser. However, for long-term use, optical absorption due to intrinsic defects does not appear, and good homogeneity and birefringence of the refractive index are maintained for a long time, making it a more stable optical member for excimer laser light. Preferably has an OH group content of 10 to 100 ppm.
【0012】本発明において、水素分子含有率は、1×
1016分子数/cm3以下とされる。水素含有率が、
1×1016分子数/cm3以下であると、照射される
エキシマレーザー光のパルス数の増加が、500mJで
1×105パルス数を越えたときに生じる紫外線領域に
おける光の透過率の低下を抑制することができる。一般
に、半導体のリソグラフィー装置に用いられる光学部材
においては、均一な露光をはかるために、耐エキシマレ
ーザー特性にばらつきが生じないように、部材中の均質
性がきびしく要求されているが、本発明者らは、特に、
合成石英ガラス光学部材の光透過面における屈折率の分
布が、屈折率の最大値と最小値の差Δnで、Δn=5×
10−6以下であれば、光学部材中の耐エキシマレーザ
ー特性が均一と見なし得ることを見い出した。即ち、Δ
n=5×10−6以下の場合は、紫外線照射に対する安
定性に好ましくないOH基及び塩素が、合成石英ガラス
光学部材中に、ほぼ均等に分布している状態となるの
で、該光学部材各部において、均等なエキシマレーザー
耐性を得ることができる。更に前記屈折率の分布の均質
性は、例えば、レンズ等の光学部材の場合に好ましい特
性である。In the present invention, the hydrogen molecule content is 1 ×.
The number is 10 16 molecules / cm 3 or less. The hydrogen content is
When it is 1 × 10 16 molecules / cm 3 or less, the increase in the pulse number of the excimer laser light to be irradiated decreases the light transmittance in the ultraviolet region which occurs when the pulse number exceeds 1 × 10 5 pulses at 500 mJ. Can be suppressed. Generally, in an optical member used in a semiconductor lithography apparatus, in order to achieve uniform exposure, homogeneity in the member is strictly required so that there is no variation in excimer laser resistance characteristics. Especially
The refractive index distribution on the light transmitting surface of the synthetic quartz glass optical member is Δn = 5 ×, where Δn is the difference between the maximum and minimum values of the refractive index.
It has been found that the excimer laser resistance characteristic in the optical member can be regarded as uniform if it is 10 −6 or less. That is, Δ
When n = 5 × 10 −6 or less, OH groups and chlorine, which are not preferable for stability against ultraviolet irradiation, are in a state of being almost evenly distributed in the synthetic quartz glass optical member. In, even excimer laser resistance can be obtained. Furthermore, the homogeneity of the refractive index distribution is a preferable characteristic in the case of an optical member such as a lens.
【0013】本発明において、このような光学用合成石
英ガラス部材を製造するための石英ガラスの原料として
は、金属不純物の混入を極力少なくするために、例え
ば、メチルトリメトキシシラン〔Si(CH3)(OC
H3)3)、テトラメトキシシラン〔Si((OC
H3)4〕等のアルキルポリアルコキシシラン若しくは
アルコキシシラン又はその他のシラン化合物或は四塩化
珪素等の揮発性無機珪素化合物などの揮発性珪素化合物
が使用される。本発明において、揮発性珪素化合物を、
揮発させ、直接火炎加水分解法により、加水分解させ
て、微粒子状のシリカガラスを生成し、このシリカガラ
スを耐熱性基体上に堆積させて、合成シリカガラスの棒
状の多孔質母材、所謂スートを製造する。In the present invention, as a raw material of quartz glass for producing such an optical synthetic quartz glass member, for example, methyltrimethoxysilane [Si (CH 3 ) (OC
H 3 ) 3 ), tetramethoxysilane [Si ((OC
Alkyl polyalkoxysilanes or alkoxysilanes such as H 3 ) 4 ] or other silane compounds or volatile silicon compounds such as volatile inorganic silicon compounds such as silicon tetrachloride are used. In the present invention, the volatile silicon compound is
It is volatilized and hydrolyzed by a direct flame hydrolysis method to produce fine particle silica glass, and this silica glass is deposited on a heat-resistant substrate to form a rod-shaped porous base material of synthetic silica glass, so-called soot. To manufacture.
【0014】本発明において、多孔質合成シリカガラス
母材は、例えば、気相軸付け法(VAD法)及び外付け
CVD法で製造でき、もとより、本発明における多孔質
合成シリカガラス母材は、合成シリカガラスの多孔質集
合体であれば足りるので、これらの製造方法に限定され
るものではない。本発明において、この多孔質合成シリ
カガラス母材中には、酸水素炎により形成されるOH基
が混入しているので、OH基による固有欠陥の生成を避
けるために、合成シリカガラス中のOH基の除去が行わ
れる。従来、例えば光ファイバー用のガラスでは、ガラ
ス中のOH基を極力減少させるために、多孔質のシリカ
ガラスの合成段階又は透明ガラス化の段階で、塩素ガス
(Cl2)を脱水剤とし、塩素ガス中で熱処理する方法
が行われている。しかし、この方法では、OHを低減さ
せても、ガラス中に塩素が残留してしまい、固有欠陥の
生成を避けることができない。また不活性ガス中で熱処
理するとしても、常圧で処理する限り、ガラス中にガス
が溶け込んで、この場合も固有欠陥を生成する。In the present invention, the porous synthetic silica glass base material can be produced, for example, by a vapor phase axial attachment method (VAD method) and an external CVD method. Of course, the porous synthetic silica glass base material in the present invention is Since a porous aggregate of synthetic silica glass is sufficient, it is not limited to these production methods. In the present invention, since the OH groups formed by the oxyhydrogen flame are mixed in this porous synthetic silica glass base material, in order to avoid the generation of intrinsic defects due to the OH groups, OH in the synthetic silica glass is avoided. Removal of groups is performed. Conventionally, for example, in glass for optical fibers, in order to reduce OH groups in the glass as much as possible, chlorine gas (Cl 2 ) is used as a dehydrating agent in the step of synthesizing porous silica glass or the step of transparent vitrification, and chlorine gas is used. The method of heat-treating is performed in it. However, in this method, even if OH is reduced, chlorine remains in the glass, and the generation of intrinsic defects cannot be avoided. Even if the heat treatment is carried out in an inert gas, as long as the heat treatment is carried out under normal pressure, the gas dissolves in the glass, and in this case also, intrinsic defects are generated.
【0015】一方、多孔質シリカガラス母材には、OH
基の他に、酸水素炎からの水素分子の可成りの量が固溶
している。このシリカガラス母材中に固溶して残留する
所謂残留水素分子については、例えば、直接法による合
成石英ガラスにおいて、5×1016分子数/cm3以
上の水素分子濃度で、残留水素分子が前記シリカガラス
母材中に固溶する場合に、紫外領域における吸収帯の発
生を抑制することが分かっている(米国特許第5,08
6,352号明細書)。しかし、5×1016分子数/
cm3以下の水素分子濃度で、残留水素分子が前記シリ
カガラス母材中に固溶する場合には、紫外領域における
吸収帯の発生の抑制がみられず、むしろ紫外領域におけ
る吸収帯の発生は増加する傾向にあることが見出されて
いる。On the other hand, the porous silica glass base material contains OH
In addition to the base, a significant amount of molecular hydrogen from the oxyhydrogen flame is in solution. Regarding the so-called residual hydrogen molecules that remain as a solid solution in the silica glass base material, for example, in synthetic quartz glass by the direct method, the residual hydrogen molecules are present at a hydrogen molecule concentration of 5 × 10 16 molecules / cm 3 or more. It has been found that when it forms a solid solution in the silica glass base material, the generation of absorption bands in the ultraviolet region is suppressed (US Pat. No. 5,083).
6,352). However, 5 × 10 16 molecules /
When the residual hydrogen molecules form a solid solution in the silica glass base material at a hydrogen molecule concentration of 3 cm 3 or less, the suppression of the generation of the absorption band in the ultraviolet region is not observed, but rather the generation of the absorption band in the ultraviolet region does not occur. It has been found to be on the rise.
【0016】これに対し、本発明者らは、1×1016
分子数/cm3以下の水素分子濃度で、残留水素分子が
前記シリカガラス母材中に固溶する場合には、紫外領域
における吸収帯の発生が抑制されることを見出した。そ
こで、本発明においては、前記合成シリカガラスを、1
×10−2トール以上の高真空度、即ち1×10−2ト
ール以下の圧力の雰囲気中で、例えば1350乃至17
00℃の温度範囲内の温度に加熱して、透明ガラス化が
行なわれる。この合成シリカガラスの透明ガラス化の処
理の真空度及び加熱温度は、合成シリカガラスに含有さ
れるOH基及び金属不純物を揮散させて除去できるよう
に選ばれ、殊に、加熱温度は、多孔質母材の大きさ及び
透明ガラス化処理時間に関連して、上記温度範囲内でで
きる限り低い温度域とするのが好ましい。On the other hand, the present inventors have obtained 1 × 10 16
It has been found that when residual hydrogen molecules form a solid solution in the silica glass base material at a hydrogen molecule concentration of not more than the number of molecules / cm 3 , generation of an absorption band in the ultraviolet region is suppressed. Therefore, in the present invention, the synthetic silica glass is
For example, 1350 to 17 in a high vacuum degree of 10-2 Torr or more, that is, in an atmosphere having a pressure of 110-2 Torr or less.
Transparent vitrification is carried out by heating to a temperature within the temperature range of 00 ° C. The degree of vacuum and the heating temperature for the transparent vitrification treatment of the synthetic silica glass are selected so that the OH groups and metal impurities contained in the synthetic silica glass can be removed by volatilization and removal. With respect to the size of the base material and the transparent vitrification treatment time, it is preferable to set the temperature range as low as possible within the above temperature range.
【0017】上記合成シリカガラスの多孔質母材のガラ
ス化は、該母材の合成シリカガラス微粒子の表面の、次
の反応式に示されるシラノール基(SiOH)の脱水縮
合反応によるものである。 2SiOH→SiOSi+H2O このシラノール基の脱水縮合反応で生成する水分は、シ
リカガラス微粒子間から外部に拡散することによって除
去されるので、OH基の除去には、生成した水分子がシ
リカガラス微粒子間から外部に拡散する時間の間透明ガ
ラス化処理を行うことが必要である。したがって、この
反応の際に、ガラス化温度が1700℃以上であると、
シリカガラス表面において、上記の脱水縮合反応が十分
に完結しない中に、シリカガラス微粒子間の焼結反応が
早く進行して、前記多孔質シリカガラス母材が透明ガラ
ス化されて、合成石英ガラス中にOH基が除去されずに
残留することとなる。The vitrification of the porous base material of the synthetic silica glass is based on the dehydration condensation reaction of the silanol group (SiOH) represented by the following reaction formula on the surface of the synthetic silica glass fine particles of the base material. 2SiOH → SiOSi + H 2 O Since the water generated by the dehydration condensation reaction of the silanol groups is removed by diffusing outside between the silica glass fine particles, the generated water molecules are removed between the silica glass fine particles to remove the OH groups. It is necessary to carry out a transparent vitrification treatment during the time of diffusion from the outside. Therefore, when the vitrification temperature is 1700 ° C. or higher during this reaction,
On the silica glass surface, while the dehydration condensation reaction is not completed sufficiently, the sintering reaction between the silica glass fine particles progresses rapidly, and the porous silica glass base material is transparentized into a synthetic quartz glass. Therefore, the OH group remains without being removed.
【0018】一方、上記のシラノール基の脱水縮合反応
は、焼結温度よりも低い温度、例えば、800℃程度の
温度でも進行するので、合成石英ガラスからOH基を除
去するには、シリカガラスの微粒子間の焼結が進行しな
い間に、上記シラノール基の脱水縮合反応を完結させ、
OH基の拡散除去を行うようにすることが必要である。
そこで、石英ガラスからOH基を除去するには、例え
ば、800乃至1200℃の温度範囲内の温度に一定時
間保持して、上記シラノール基の脱水縮合反応を促進さ
せた後、より高い温度に加熱して、シリカガラス微粒子
間の焼結を行って、透明ガラス化を行うという、二段階
の透明ガラス化を行うことが好ましい。On the other hand, the above silanol group dehydration condensation reaction proceeds even at a temperature lower than the sintering temperature, for example, at a temperature of about 800 ° C. Therefore, in order to remove the OH group from the synthetic quartz glass, silica glass While the sintering between the fine particles does not proceed, complete the dehydration condensation reaction of the silanol group,
It is necessary to diffuse and remove the OH group.
Therefore, in order to remove the OH group from the quartz glass, for example, the temperature is kept within a temperature range of 800 to 1200 ° C. for a certain period of time to accelerate the dehydration condensation reaction of the silanol group, and then heated to a higher temperature. Then, it is preferable to perform a two-step transparent vitrification, that is, to perform transparent vitrification by sintering the silica glass fine particles.
【0019】また、合成シリカガラスの透明ガラス化を
ゾーンメルト法により行う場合には、上記のシラノール
基の脱水縮合反応をできるだけ緩やかに行うような条件
で透明ガラス化することが必要である。即ち、加熱領域
の移動をできるだけゆっくりと行うか、加熱温度をでき
るだけ低温で行うべきである。一般的には、大きな多孔
質シリカガラス母材になるほど、加熱領域の移動は遅く
する方が好ましい。透明ガラス化時のシラノール基の脱
水縮合反応により生成する水(H2O)、できるだけ早
く拡散させて、外部に放出させるには、少なくとも10
−2トール以上の高真空雰囲気をガラス化処理中に保持
することが必要なことが分かった。ここで重要なこと
は、シラノール基の脱水縮合反応時及び透明ガラス化反
応時には、10−2トール以上の高真空度、即ち10
−2トール以下の圧力に保つことが必要である。なお、
処理されるシリカガラスの多孔質母材が大きい場合に
は、生成するH2Oの量もかなり多くなるため、使用す
る真空排気装置は、到達真空度の高いものより、排気速
度の高いものが有効である。When the synthetic silica glass is made transparent by vitrification by the zone melt method, it is necessary to make it transparent under the condition that the dehydration condensation reaction of the silanol group is carried out as gently as possible. That is, the heating area should be moved as slowly as possible or the heating temperature should be as low as possible. Generally, the larger the porous silica glass base material, the slower the movement of the heating region. Water (H 2 O) generated by the dehydration condensation reaction of silanol groups at the time of vitrification is at least 10 in order to diffuse it as quickly as possible and release it to the outside.
It has been found necessary to maintain a high vacuum atmosphere above -2 Torr during the vitrification process. What is important here is that the dehydration condensation reaction of the silanol group and the transparent vitrification reaction have a high vacuum degree of 10 −2 Torr or more, that is, 10 −2 Torr or more.
-It is necessary to keep the pressure below -2 Torr. In addition,
When the porous base material of the silica glass to be treated is large, the amount of H 2 O produced is considerably large. Therefore, the vacuum evacuation device to be used should have a higher evacuation rate than a high evacuation degree. It is valid.
【0020】このようにして製造された合成石英ガラス
は、OH濃度が低濃度であり、つまり合成石英ガラス中
のOHの含有量が50ppm以下、好ましくは、30p
pm以下であり、金属不純物の含有量も極めて少なく、
高純度の透明石英ガラスである。CVD法により製造さ
れた石英ガラスは、その製造時の温度変化によって、耐
熱性基体上のシリカガラス微粒子堆積体に密度の揺らぎ
を生じるが、この揺らぎが、透明ガラス化後に脈理とし
て残留するので、通常CVD法により製造された透明石
英ガラスは、脈理を有していることが一般的である。The synthetic quartz glass produced in this manner has a low OH concentration, that is, the OH content in the synthetic quartz glass is 50 ppm or less, preferably 30 p.
pm or less, the content of metal impurities is extremely low,
It is a high-purity transparent quartz glass. Quartz glass manufactured by the CVD method has density fluctuations in the silica glass fine particle deposits on the heat-resistant substrate due to temperature changes during its manufacture, but these fluctuations remain as striae after transparent vitrification. In general, transparent quartz glass produced by the CVD method generally has striae.
【0021】しかし、ステッパーレンズ等の光学用部材
とするには、この脈理を除去しなければならない。そこ
で、本発明においては、前記高純度の透明石英ガラス
を、例えば、米国特許第2,904,713号、米国特
許第3,128,166号、米国特許第3,128,1
69号、米国特許第3,485,613号等に開示され
た方法により処理して、脈理を除去する必要がある。例
えば、脈理のある棒状の透明合成石英ガラスを旋盤で保
持し、棒状の透明石英ガラスの局部をバーナーもしくは
電気加熱により加熱する方法で、少なくとも透明合成石
英ガラスを、軟化点以上に加熱し、旋盤を回転させ、脈
理が消えるまで棒状の合成石英ガラスを捻る方法があ
る。However, this striae must be removed to form an optical member such as a stepper lens. Therefore, in the present invention, the high-purity transparent quartz glass is used, for example, in US Pat. No. 2,904,713, US Pat. No. 3,128,166, and US Pat. No. 3,128,1.
No. 69, U.S. Pat. No. 3,485,613, and the like to remove the striae by treatment according to the method disclosed therein. For example, a rod-shaped transparent synthetic quartz glass having a striae is held by a lathe, and a method of heating a local portion of the rod-shaped transparent quartz glass by a burner or electric heating, at least transparent synthetic quartz glass is heated to a softening point or higher, There is a method of rotating a lathe and twisting a rod-shaped synthetic quartz glass until the striae disappear.
【0022】この方法においては、脈理を除去する際
に、棒状の合成石英ガラスの加熱位置を順次移動するこ
とによって、最終的には棒状の合成石英ガラス全体が均
質化される。この際の加熱温度は、石英ガラスの軟化点
以上、例えば1600℃以上にすることが必要である。
勿論、合成石英ガラス上の加熱位置の移動速度などは、
処理する石英ガラス部材の形状や重さによって適当に選
択されるものである。脈理が除去された透明合成石英ガ
ラスは、次に、最終的な製品、例えばステッパーレンズ
等に使用するために適した形状、サイズに成形される。
この成形は、一般に、所望の形状のルツボ内に脈理を除
去した透明合成石英ガラスを入れ、これを加熱炉で少な
くとも1500℃以上に加熱し、石英ガラスの自重で成
形する。この場合、従来法と同様に、カーボン製のルツ
ボが一般に使用できる。また、加熱炉も、従来法と同様
に、カーボンヒータ仕様のものが使用できる。このた
め、成形は、真空又はHe若しくはN2などの不活性ガ
ス雰囲気中で行われる。この成形時における加熱温度及
び加熱時間などの成形条件は、所望する成形体のサイズ
や形状に応じて適宜選択される。In this method, when the striae are removed, the heating position of the rod-shaped synthetic quartz glass is sequentially moved so that the entire rod-shaped synthetic quartz glass is finally homogenized. The heating temperature at this time needs to be higher than the softening point of the quartz glass, for example, 1600 ° C. or higher.
Of course, the moving speed of the heating position on the synthetic quartz glass,
It is appropriately selected depending on the shape and weight of the quartz glass member to be treated. The striae-cleared transparent synthetic quartz glass is then formed into a shape and size suitable for use in a final product, such as a stepper lens.
This molding is generally carried out by placing the striae-free transparent synthetic quartz glass in a crucible of a desired shape, heating it to at least 1500 ° C. in a heating furnace, and molding the quartz glass by its own weight. In this case, a carbon crucible can generally be used as in the conventional method. Further, as the heating furnace, one having a carbon heater specification can be used as in the conventional method. Therefore, the molding is performed in a vacuum or an atmosphere of an inert gas such as He or N 2 . Molding conditions such as heating temperature and heating time during this molding are appropriately selected according to the desired size and shape of the molded body.
【0023】一般的に光学材料は、歪が5nm/cm以
下であることが要求されるので、本発明においては、成
形された透明合成石英ガラスは、その成形歪をアニール
処理により除去することが必要である。この成形歪みの
除去は、成形された透明合成石英ガラスを、石英ガラス
の歪点よりも高い温度まで加熱し、その後、該成形され
た透明合成石英ガラスを徐冷することにより行われる。
一般に、合成石英ガラスの歪点は約1025℃であるの
で、本発明においては、成形された透明合成石英ガラス
は、その成形歪みをほぼ完全に除去させるために、11
00℃乃至1250℃の範囲内の温度まで加熱され、徐
冷される。徐冷はできるだけゆっくり行われるのが好ま
しい。本発明においては、アニール処理は合成石英ガラ
ス中の屈折率分布の均一化にも貢献している。Generally, the optical material is required to have a strain of 5 nm / cm or less. Therefore, in the present invention, the molding strain of the molded transparent synthetic quartz glass can be removed by annealing treatment. is necessary. This molding strain is removed by heating the molded transparent synthetic quartz glass to a temperature higher than the strain point of the quartz glass, and then gradually cooling the molded transparent synthetic quartz glass.
Generally, since the strain point of synthetic quartz glass is about 1025 ° C., in the present invention, the molded transparent synthetic quartz glass has a strain point of 11% in order to remove the molding strain almost completely.
It is heated to a temperature within the range of 00 ° C to 1250 ° C and then gradually cooled. The slow cooling is preferably performed as slowly as possible. In the present invention, the annealing treatment also contributes to making the refractive index distribution in the synthetic quartz glass uniform.
【0024】合成石英ガラスの屈折率の分布は、主に、
OH基や塩素などの不純物含有量と仮想温度(fict
ive temperature)により決定される。
これらのうち、本発明の合成石英ガラス光学部材のOH
基は数10ppm以下なので無視することができ、その
他の不純物も本発明の合成石英ガラス光学部材の場合、
実質的に無視することができるので、アニール処理の際
の仮想温度の設定が重要である。つまり、均一な屈折率
分布を得るためには、処理する成形された合成石英ガラ
ス、即ち、合成石英ガラス成形体についての全体の仮想
温度を均一にしなければならない。この為、一旦徐冷点
以上の温度に合成石英ガラス成形体を加熱したのち、一
定時間その温度で保持して合成石英ガラス成形体内部の
温度分布を均一にし、その後できるだけゆっくりと降温
する。これは、石英ガラス成形体全体で、できるだけ温
度差を生じないようにするためである。この場合、この
降温速度を速くすると、合成石英ガラス成形体中の任意
の位置で温度差が生じ、その結果、異なる仮想温度が設
定され、均一な屈折率分布が得られない。The refractive index distribution of synthetic quartz glass is
Impurity content such as OH and chlorine and fictive temperature
IVE temperature).
Of these, OH of the synthetic quartz glass optical member of the present invention
Since the amount of the group is several tens of ppm or less, it can be ignored, and other impurities in the case of the synthetic quartz glass optical member of the present invention are
The setting of the fictive temperature during the annealing is important because it can be substantially ignored. That is, in order to obtain a uniform refractive index distribution, the entire fictive temperature of the molded synthetic quartz glass to be processed, that is, the synthetic quartz glass molded body must be uniform. For this reason, the synthetic quartz glass compact is once heated to a temperature equal to or higher than the annealing point, and then kept at that temperature for a certain period of time to make the temperature distribution inside the synthetic quartz glass compact uniform, and then the temperature is lowered as slowly as possible. This is for minimizing the temperature difference in the entire quartz glass molded body. In this case, if the temperature decreasing rate is increased, a temperature difference occurs at an arbitrary position in the synthetic quartz glass molded body, and as a result, different virtual temperatures are set, and a uniform refractive index distribution cannot be obtained.
【0025】本発明においては、上記のアニール処理に
おける加熱温度は1200℃程度であり、加熱時間及び
降温スピードは、アニール処理する合成石英ガラス成形
体の大きさや形状を考慮して、適当に選ばれる。一般的
に、合成石英ガラス成形体の大きさが大きいものほど、
加熱時間を長くし、かつ降温スピードを遅くするのが好
ましい。本発明による合成石英ガラス光学部材は、OH
基の含有量が10乃至100ppm以下で、かつ塩素の
含有量が200ppm以下であるので、紫外線照射によ
って生じる常磁性欠陥の総量が低減でき、エキシマレー
ザー光の照射下に長時間に渡って安定した光学特性を得
ることができる。しかも、本発明によるエキシマレーザ
ー用合成石英ガラス光学部材は、その光透過面における
屈折率の分布Δnが、5×10−6以下であるので、エ
キシマレーザー光の照射下に、光学部材全体に亙って均
一なエキシマレーザー安定性が得られる。In the present invention, the heating temperature in the above-mentioned annealing treatment is about 1200 ° C., and the heating time and the temperature lowering speed are appropriately selected in consideration of the size and shape of the synthetic quartz glass compact to be annealed. . Generally, the larger the synthetic quartz glass molded body,
It is preferable to lengthen the heating time and slow the temperature lowering speed. The synthetic quartz glass optical member according to the present invention is
Since the content of the group is 10 to 100 ppm or less and the content of chlorine is 200 ppm or less, the total amount of paramagnetic defects caused by the irradiation of ultraviolet rays can be reduced, and stable for a long time under the irradiation of excimer laser light. Optical characteristics can be obtained. Moreover, since the synthetic quartz glass optical member for excimer laser according to the present invention has a refractive index distribution Δn of 5 × 10 −6 or less on the light transmitting surface thereof, the entire optical member is irradiated with the excimer laser light. Therefore, uniform excimer laser stability can be obtained.
【0026】本発明においては、揮発性珪素化合物を、
酸水素炎により火炎加水分解し、生成する微粒子の合成
シリカを耐熱性基体上に堆積させて合成シリカガラスの
多孔質母材を製造し、該合成シリカガラスの多孔質母材
を1×10−2トール以上の高真空度下で加熱して、透
明な合成石英ガラスを形成し、該透明合成石英ガラスを
均質化処理することにより、少なくとも一方向、好まし
くは三方向に脈理を有しない高均質合成石英ガラスを形
成し、次いで該高均質合成石英ガラスを成形し、成形後
アニール処理するので、得られる合成石英ガラス光学部
材は、紫外線照射によって生成する常磁性欠陥のもとに
なる固有欠陥、例えばSiOHや塩素などのその他の不
純物による固有欠陥が低減され、結果的に常磁性欠陥の
生成は抑制される。以上のように本発明により製造され
たエキシマレーザー用石英ガラス部材は、均質性がよ
く、かつ、耐エキシマレーザー性に優れており、殊に、
エキシマレーザーを光源とするステッパーレンズ用の石
英ガラスとして好適であり、また、紫外線照射に伴う紫
外線領域の吸収の増加を抑制することができる。In the present invention, the volatile silicon compound is
Flame-hydrolysis by an oxyhydrogen flame and fine particles of synthetic silica produced are deposited on a heat-resistant substrate to produce a porous base material of synthetic silica glass, and the porous base material of the synthetic silica glass is 1 × 10 −. By heating under a high degree of vacuum of 2 Torr or more to form a transparent synthetic quartz glass and subjecting the transparent synthetic quartz glass to a homogenizing treatment, a high degree of striae which has no striae in at least one direction, preferably three directions. Since the homogeneous synthetic quartz glass is formed, then the highly homogeneous synthetic quartz glass is molded, and annealed after the molding, the synthetic quartz glass optical member obtained has an intrinsic defect which is a source of paramagnetic defects generated by ultraviolet irradiation. Inherent defects due to other impurities such as SiOH and chlorine are reduced, and as a result, generation of paramagnetic defects is suppressed. As described above, the silica glass member for excimer laser produced by the present invention has good homogeneity and is excellent in excimer laser resistance, in particular,
It is suitable as quartz glass for a stepper lens that uses an excimer laser as a light source, and can also suppress an increase in absorption in the ultraviolet region due to ultraviolet irradiation.
【0027】[0027]
【実施例】本発明の実施態様について、以下、例を挙げ
て説明するが、本発明は、以下の説明及び例示によっ
て、何等制限されるものではない。 例1.四塩素珪素を酸水素バーナー中に導入し、火炎加
水分解して得られる微細なシリカ粒子を回転するターゲ
ット上に堆積させて、重量1Kgの多孔質合成シリカ堆
積物を形成した。該多孔質合成シリカ堆積物を雰囲気炉
に入れ、800℃に昇温、そのまま保持後、塩素、酸
素、窒素、1:1:8の混合ガスを10リットル/分の
流量で流しながら、10時間加熱処理後、該多孔質合成
シリカを取り出し、真空炉に入れて、1×10−2の真
空下で、1600℃の温度に昇温し、1時間保持した
後、冷却し透明な棒状の合成石英ガラスを作成した。EXAMPLES The embodiments of the present invention will be described below with reference to examples, but the present invention is not limited to the following descriptions and examples. Example 1. Silicon tetrachloride was introduced into an oxyhydrogen burner and fine silica particles obtained by flame hydrolysis were deposited on a rotating target to form a porous synthetic silica deposit weighing 1 Kg. The porous synthetic silica deposit was placed in an atmosphere furnace, heated to 800 ° C., kept as it was, while flowing a mixed gas of chlorine, oxygen, nitrogen and 1: 1: 8 at a flow rate of 10 liter / min for 10 hours. After the heat treatment, the porous synthetic silica was taken out, placed in a vacuum furnace, heated to a temperature of 1600 ° C. under a vacuum of 1 × 10 −2 , held for 1 hour, and then cooled to obtain a transparent rod-shaped synthesis. Quartz glass was created.
【0028】該合成石英ガラスの両端を旋盤に固定し、
旋盤を回転しつつ、プロパンガスバーナーで軟化点以上
に加熱しながら均質化処理を行った。均質化処理された
合成石英ガラスをグラファイト鋳型内にセットし、窒素
雰囲気中で1700℃に加熱成形した後、大気中でアニ
ール処理を行った。アニール処理は1100℃で20時
間保持後0.5℃/分で600℃まで除冷して行った。
得られた合成石英ガラス成形体から分析用サンプルを採
集した後、外周部を研削後、端面を鏡面研磨して外径8
0mm、厚さ20mmのエキシマレーザー光学窓用合成
石英ガラス成形体を作成した。この得られたエキシマレ
ーザー光学窓用合成石英ガラス成形体のOH基含有率を
赤外分光光度法で測定したところ、20ppmであり、
ラマン散乱法により測定した残留水素分子の水素分子濃
度は、1×1016分子数/cm3以下であった。また
該光学窓用合成石英ガラス成形体の紫外線透過率を紫外
分光光度計で測定したところ245nmに於ける吸収は
観測されず、内部透過率は99%以上であった。図1
に、実施例1の光学窓用合成石英ガラス成形体の透過率
曲線を示す。内部透過率は、図1中の透過率から試料の
反射によるロスを減じた透過率を厚さ1cmに於ける透
過率に換算したものである。Both ends of the synthetic quartz glass are fixed to a lathe,
The homogenization treatment was carried out while rotating the lathe while heating with a propane gas burner above the softening point. The homogenized synthetic quartz glass was set in a graphite mold, heated and molded at 1700 ° C. in a nitrogen atmosphere, and then annealed in the atmosphere. The annealing treatment was carried out by holding at 1100 ° C. for 20 hours and then cooling to 0.5 ° C./min to 600 ° C.
After collecting an analytical sample from the obtained synthetic quartz glass molded body, the outer peripheral portion was ground, and the end surface was mirror-polished to give an outer diameter of 8
A synthetic quartz glass molded body for an excimer laser optical window having a thickness of 0 mm and a thickness of 20 mm was prepared. When the OH group content of the obtained synthetic quartz glass molded body for an excimer laser optical window was measured by an infrared spectrophotometric method, it was 20 ppm,
The hydrogen molecule concentration of residual hydrogen molecules measured by Raman scattering was 1 × 10 16 molecules / cm 3 or less. Further, when the ultraviolet transmittance of the synthetic quartz glass molded body for an optical window was measured by an ultraviolet spectrophotometer, no absorption at 245 nm was observed and the internal transmittance was 99% or more. Figure 1
The transmittance curve of the synthetic quartz glass molded body for an optical window of Example 1 is shown in FIG. The internal transmittance is the transmittance obtained by subtracting the loss due to the reflection of the sample from the transmittance shown in FIG. 1 and converted into the transmittance at a thickness of 1 cm.
【0029】また分析用サンプルを弗酸で分解し、硝酸
銀比濁法で塩素濃度を測定したところ100ppmであ
った。さらに、上記光学窓用合成石英ガラス成形体の屈
折率分布を、フィゾー干渉計により、オイルオンプレー
ト法でHeNeレーザー光を用いて測定したところ、Δ
nは1×10−6であり、複屈折は2nmであった。該
光学窓用合成石英ガラス成形体にKrFエキシマレーザ
ーをフルエンス500mJ/cm2p,100Hzで照
射し、その紫外域の吸光度変化を測定した。測定結果を
図2に示す。図2ではE’センターの吸収波長である2
15nmにおける吸光度(−Log(内部吸収))のシ
ョット数における経時変化を示している。後述する比較
例1に比べて、照射に対して吸光度変化が少なく、光学
部材として良好な特性を示している。The sample for analysis was decomposed with hydrofluoric acid and the chlorine concentration was measured by the silver nitrate nephelometry to find that it was 100 ppm. Further, the refractive index distribution of the synthetic quartz glass molded body for the optical window was measured by a Fizeau interferometer by an oil-on-plate method using HeNe laser light.
n was 1 × 10 −6 and the birefringence was 2 nm. The synthetic quartz glass molding for an optical window was irradiated with KrF excimer laser at a fluence of 500 mJ / cm 2 p, 100 Hz, and the change in absorbance in the ultraviolet region was measured. The measurement results are shown in FIG. In Fig. 2, the absorption wavelength of the E'center is 2
It shows the change with time in the number of shots of the absorbance (-Log (internal absorption)) at 15 nm. Compared with Comparative Example 1 to be described later, the change in absorbance with respect to irradiation was small, and good characteristics as an optical member were exhibited.
【0030】なお本例において、合成石英ガラス中の残
留水素分子の水素分子濃度は、ラマン散乱法により測定
された(Zhurnal Prikladnoi Sp
ektroskopii vol.46,No.6,p
p.987 to 991,june 1987)。こ
の方法は、SiO2に関する波数800cm−1のラマ
ンバンドの強度と合成石英ガラス中に含有される水素分
子に関する4135cm−1の強度との比により、合成
石英ガラス中の水素分子濃度を求めるものであり、水素
分子濃度Cは、次の式(1)により算出される。 C=kI4135/I800 (1) (式(1)中I4135は、4135cm−1のラマン
バンドの面積強度である。I800は、800cm−1
のラマンバンドの面積強度である。kは、定数で、1.
22×1021である。) この式により算出される水素分子濃度は、1cm3の容
積当たりの水素分子の個数で示される。本例において、
ラマン散乱法による水素分子濃度の測定に使用した測定
機器は、日本分光株式会社製のラマン散乱分光器NR−
1100ダブルモノクロタイプであり、検出器は浜松フ
ォトニクス株式会社製の光電子増倍管R943−02で
あり、測定に使用したレーザー光はArイオンレーザー
(488nm)である。In this example, the hydrogen molecule concentration of residual hydrogen molecules in the synthetic quartz glass was measured by the Raman scattering method (Zhurnal Prikladnoi Sp.
ektroskopii vol. 46, No. 6, p
p. 987 to 991, jun 1987). This method is to determine the hydrogen molecule concentration in synthetic quartz glass by the ratio of the Raman band intensity of 800 cm −1 for SiO 2 and the intensity of 4135 cm −1 for hydrogen molecules contained in the synthetic quartz glass. Yes, the hydrogen molecule concentration C is calculated by the following equation (1). C = kI 4135 / I 800 (1) (In the formula (1), I 4135 is the area intensity of the Raman band at 4135 cm −1. I 800 is 800 cm −1.
Is the Raman band area intensity. k is a constant, 1.
It is 22 × 10 21 . ) The hydrogen molecule concentration calculated by this formula is indicated by the number of hydrogen molecules per volume of 1 cm 3 . In this example,
The measuring instrument used to measure the hydrogen molecule concentration by the Raman scattering method is a Raman scattering spectrometer NR- manufactured by JASCO Corporation.
1100 double monochrome type, the detector is a photomultiplier tube R943-02 manufactured by Hamamatsu Photonics K.K., and the laser beam used for the measurement is an Ar ion laser (488 nm).
【0031】例2.前記例1と同様に多孔質合成シリカ
堆積物を作成し、雰囲気炉中で800℃に保持後塩素、
酸素、窒素、1:2:7の混合ガスを10リットル/分
の流量で流しながら10時間加熱処理後、該多孔質合成
シリカを取り出し、真空炉中で1×10−2の真空下で
1600℃の温度に昇温し、1時間保持した後冷却し
て、透明な棒状の合成石英ガラスを作成した。該合成石
英ガラスを、例1と同様に成形し、アニール処理し、分
析用サンプル及び外径80mm、厚さ20mmのエキシ
マレーザー光学窓用合成石英ガラス成形体を作成した。
この得られたエキシマレーザー光学窓用合成石英ガラス
成形体は、OH基含有率が、90ppmであり、塩素含
有率は20ppmであった。また該光学窓用合成石英ガ
ラス成形体において、245nmにおける内部透過率は
99%以上であった。該光学窓用合成石英ガラス成形体
を実施例1と同様の条件で、KrFレーザー照射を行っ
た際の248nmの吸光度変化を測定したところ、例1
と同様の結果が得られ、良好な安定性を示している。Example 2. A porous synthetic silica deposit was prepared in the same manner as in Example 1 above, kept at 800 ° C. in an atmospheric furnace, and then chlorine,
After heat treatment for 10 hours while flowing a mixed gas of oxygen, nitrogen and 1: 2: 7 at a flow rate of 10 liters / minute, the porous synthetic silica was taken out and placed in a vacuum furnace under a vacuum of 1 × 10 −2 to 1600. The temperature was raised to a temperature of ° C, the temperature was maintained for 1 hour and then cooled to prepare a transparent rod-shaped synthetic quartz glass. The synthetic quartz glass was molded in the same manner as in Example 1 and annealed to prepare a sample for analysis and a synthetic quartz glass molded body for an excimer laser optical window having an outer diameter of 80 mm and a thickness of 20 mm.
The obtained synthetic quartz glass molding for an excimer laser optical window had an OH group content of 90 ppm and a chlorine content of 20 ppm. In addition, in the synthetic quartz glass molded body for an optical window, the internal transmittance at 245 nm was 99% or more. When the synthetic quartz glass molded body for an optical window was irradiated with a KrF laser under the same conditions as in Example 1, the change in absorbance at 248 nm was measured.
The result is similar to the above, and shows good stability.
【0032】例3 例1と同様に作成した、透明合成石英ガラスにおいて、
均質化の際の処理時間を半分にし、他の条件は例1と同
様にして、一連の処理を行い、分析用サンプル及び外径
80mm、厚さ20mmのエキシマレーザー光学窓用合
成石英ガラス成形体を作成した。この得られたエキシマ
レーザー光学窓用合成石英ガラス成形体は、OH基含有
率が90ppm、塩素含有率は20ppmであった。ま
たこの光学窓用合成石英ガラス成形体においても245
nmにおける内部透過率は99%以上であり、複屈折は
2nmであった。該光学窓用合成石英ガラス成形体にお
ける屈折率の分布Δnを測定したところ、5×10−6
であった。屈折率分布を示す干渉縞を図3に示す。該光
学窓用合成石英ガラス成形体の中央部と外周部より、1
0mm×10mm×40mmのサンプルを切り出し、実
施例1と同様の条件でKrFレーザー照射を行った際の
248nmの吸光度変化を図4に示す。中央部と外周部
共に良好な安定性を示し、かつ吸光度の変化も同様であ
るために、光学部材としての均一性が維持されていると
いえる。Example 3 In a transparent synthetic quartz glass prepared in the same manner as in Example 1,
The treatment time in homogenization was halved, and the other conditions were the same as in Example 1, and a series of treatments were performed, and a sample for analysis and a synthetic quartz glass molding for an excimer laser optical window with an outer diameter of 80 mm and a thickness of 20 mm were used. It was created. The obtained synthetic quartz glass molding for an excimer laser optical window had an OH group content of 90 ppm and a chlorine content of 20 ppm. Also, in this synthetic quartz glass molding for optical windows, 245
The internal transmittance in nm was 99% or more, and the birefringence was 2 nm. The refractive index distribution Δn of the synthetic quartz glass molded body for an optical window was measured and found to be 5 × 10 −6.
Met. The interference fringes showing the refractive index distribution are shown in FIG. From the central part and the outer peripheral part of the synthetic quartz glass molding for the optical window, 1
FIG. 4 shows the change in absorbance at 248 nm when a 0 mm × 10 mm × 40 mm sample was cut out and subjected to KrF laser irradiation under the same conditions as in Example 1. It can be said that the uniformity as the optical member is maintained because the central portion and the outer peripheral portion both show good stability and the changes in the absorbance are similar.
【0033】比較例1.例1と同様に多孔質合成シリカ
を作成し、そのまま真空炉中で1×10−2の真空下で
1600℃の温度に昇温し、1時間保持した後、冷却し
透明な棒状の合成石英ガラスを作成した。該合成石英ガ
ラスを、例1と同様に処理し、分析用サンプル及び外径
80mm、厚さ20mmの光学窓用合成石英ガラス成形
体を作成した。得られた光学ウインドウのOH基含有率
は200ppm、塩素含有率は10ppmであった。ま
た同光学窓用合成石英ガラス成形体においても245n
mにおける内部透過率は99%以上であった。該光学窓
用合成石英ガラス成形体を例1と同様の条件で,KrF
レーザー照射を行った際の248nmの吸光度変化を図
2に例1の場合と共に示す。比較例1においては、例1
と比べて215nmに於ける吸光度の上昇が認められ、
エキシマレーザー用光学部材として十分な安定性を有し
ていないことが分かる。Comparative Example 1. A porous synthetic silica was prepared in the same manner as in Example 1, heated in a vacuum furnace to a temperature of 1600 ° C. under a vacuum of 1 × 10 −2 , held for 1 hour, and then cooled to obtain a transparent rod-shaped synthetic quartz. I made glass. The synthetic quartz glass was treated in the same manner as in Example 1 to prepare a sample for analysis and a synthetic quartz glass molding for an optical window having an outer diameter of 80 mm and a thickness of 20 mm. The optical window thus obtained had an OH group content of 200 ppm and a chlorine content of 10 ppm. Also in the synthetic quartz glass molding for the optical window, 245n
The internal transmittance at m was 99% or more. Under the same conditions as in Example 1, the synthetic quartz glass molded body for an optical window was subjected to KrF.
The change in absorbance at 248 nm when laser irradiation is performed is shown in FIG. 2 together with the case of Example 1. In Comparative Example 1, Example 1
Increase in absorbance at 215 nm compared to
It can be seen that the optical member for excimer laser does not have sufficient stability.
【0034】比較例2.例1と同様に多孔質合成シリカ
堆積物を作成し、雰囲気炉中で800℃に保持後、塩
素、窒素、1:9の混合ガスを10リットル/分の流量
で流しながら、5時間加熱処理後、該多孔質合成シリカ
を取り出し、真空炉中で1×10−2の真空下で160
0℃の温度に昇温し、1時間保持した後、冷却して透明
な棒状の合成石英ガラスを作成した。該合成石英ガラス
を、例1と同様に成形し、アニール処理を行い、分析用
サンプル及び外径80mm、厚さ20mmの光学窓用合
成石英ガラス成形体を作成した。得られた光学窓用合成
石英ガラス成形体のOH基含有率は1ppm、塩素含有
率は400ppmであった。また該光学窓用合成石英ガ
ラス成形体においても245nmにおける内部透過率は
94.7%であった。該光学窓用合成石英ガラス成形体
の紫外線領域における透過率曲線を図5に示す。245
nmを吸収センターとする吸収帯が現れている。該光学
窓用合成石英ガラス成形体を例1と同様の条件でKrF
レーザー照射を行った際の215nmの吸光度変化を例
1と共に図6に示す。248nmに於ける吸光度の急激
な上昇が認められ、エキシマレーザー用光学部材として
十分な安定性を有していないことを示している。Comparative Example 2. A porous synthetic silica deposit was prepared in the same manner as in Example 1, kept at 800 ° C. in an atmospheric furnace, and then heat treated for 5 hours while flowing a mixed gas of chlorine, nitrogen and 1: 9 at a flow rate of 10 liters / minute. After that, the porous synthetic silica was taken out, and 160% under a vacuum of 1 × 10 −2 in a vacuum furnace.
The temperature was raised to 0 ° C., the temperature was maintained for 1 hour, and then cooled to prepare a transparent rod-shaped synthetic quartz glass. The synthetic quartz glass was molded in the same manner as in Example 1 and annealed to prepare a sample for analysis and a synthetic quartz glass molded body for an optical window having an outer diameter of 80 mm and a thickness of 20 mm. The obtained synthetic quartz glass molding for an optical window had an OH group content of 1 ppm and a chlorine content of 400 ppm. The internal transmittance at 245 nm of the molded synthetic quartz glass for optical windows was also 94.7%. FIG. 5 shows a transmittance curve in the ultraviolet region of the synthetic quartz glass molding for the optical window. 245
An absorption band having an absorption center of nm appears. The synthetic quartz glass molding for the optical window was subjected to KrF under the same conditions as in Example 1.
The change in absorbance at 215 nm when laser irradiation is performed is shown in FIG. 6 together with Example 1. A sharp increase in the absorbance at 248 nm was observed, indicating that the optical member for excimer laser does not have sufficient stability.
【0035】例4.四塩化けい素を蒸留処理して不純物
を除去した後、これを原料として、CVD法で外形15
0mm,長さ600mmの円柱状の多孔質合成石英ガラ
ス母材を作製した。該多孔質合成石英ガラス母材を、カ
ーボンヒーター仕様の真空炉にいれ、10−5トールま
で真空排気した。この後、ヒーターを昇温し、多孔質合
成石英ガラス母材を加熱した。加熱条件は800℃まで
10℃/分で、800乃至1400℃では1℃/分の昇
温速度で加熱し、1400℃に達した時点で加熱を停止
し、自然冷却した。外径105mm,長さ550mmの
円柱状の透明合成石英ガラスが得られた。得られた透明
合成石英ガラスのOH含有率は約25ppmであった。
該円柱状透明合成石英ガラスの両端に石英ガラス製の
支持棒を取り付け、旋盤のチャックに固定した。プロパ
ンガスバーナーにより、上記の多孔質合成石英ガラス母
材より作製した透明ガラス部分を加熱し、旋盤を回転さ
せ、該透明合成石英ガラス部分を捻った。この時の作業
温度は、約2000℃であった。捻られた透明ガラス部
には3方向には脈理は観測されなかった。しかるのち、
該透明石英ガラス部分を切り出し、カーボンヒーター仕
様の加熱炉で成形し、外径250mm,長さ75mmの
円柱状の合成石英ガラス成形体を得た。この時の成形温
度は約1700℃で、窒素ガス雰囲気中で行った。Example 4. After removing impurities by distilling silicon tetrachloride, using this as a raw material, the outer shape 15
A cylindrical porous synthetic quartz glass base material having a length of 0 mm and a length of 600 mm was produced. The porous synthetic quartz glass base material was placed in a vacuum furnace with a carbon heater specification and evacuated to 10 −5 torr. Then, the heater was heated to heat the porous synthetic quartz glass base material. The heating conditions were 10 ° C./min up to 800 ° C., heating was performed at a temperature rising rate of 1 ° C./min from 800 to 1400 ° C., heating was stopped when 1400 ° C. was reached, and natural cooling was performed. A cylindrical transparent synthetic quartz glass having an outer diameter of 105 mm and a length of 550 mm was obtained. The OH content of the obtained transparent synthetic quartz glass was about 25 ppm.
Support rods made of quartz glass were attached to both ends of the cylindrical transparent synthetic quartz glass, and fixed to a chuck of a lathe. The transparent glass portion produced from the above-mentioned porous synthetic quartz glass base material was heated with a propane gas burner, the lathe was rotated, and the transparent synthetic quartz glass portion was twisted. The working temperature at this time was about 2000 ° C. No striae was observed in the twisted transparent glass part in three directions. After a while,
The transparent quartz glass portion was cut out and molded in a heating furnace with a carbon heater specification to obtain a cylindrical synthetic quartz glass molded body having an outer diameter of 250 mm and a length of 75 mm. The molding temperature at this time was about 1700 ° C., and the molding was performed in a nitrogen gas atmosphere.
【0036】該合成石英ガラス成形体について、その歪
み取りのためにアニール熱処理を行った。アニール熱処
理条件は、1100℃まで昇温したのち、0.1℃/分
で600℃まで降温した。熱処理は大気中の雰囲気で行
った。得られた合成石英ガラス成形体の複屈折は2nm
/cm以下であり、屈折率分布も実質上均一であり、屈
折率の最大値と最小値の差は1×10−6以下であっ
た。また、この合成石英ガラスに含有される残留水素分
子の水素分子濃度は、ラマン散乱法で測定したところ1
×1016分子数/cm3以下であった。The synthetic quartz glass molded body was annealed and heat treated to remove the strain. As the annealing heat treatment condition, the temperature was raised to 1100 ° C. and then lowered to 600 ° C. at 0.1 ° C./min. The heat treatment was performed in the atmosphere. Birefringence of the obtained synthetic quartz glass molded body is 2 nm
/ Cm or less, the refractive index distribution was substantially uniform, and the difference between the maximum value and the minimum value of the refractive index was 1 × 10 -6 or less. Further, the hydrogen molecule concentration of residual hydrogen molecules contained in this synthetic quartz glass was measured by Raman scattering method to be 1
It was x10 16 molecules / cm 3 or less.
【0037】紫外線照射に対する常磁性欠陥の生成を調
べるために、上記の透明石英ガラス成型体の一部を切り
出し、境面を研磨して10mm×10mm×40mmの
透明合成石英ガラス成形体に加工した。該合成石英ガラ
ス成形体にArFレーザーを照射し、193nmの光の
透過率の変化を調べた。ArFレーザーの照射条件は、
エネルギー密度200mJ/cm2・パルス、周波数1
00ヘルツで行った。図7にArF照射パルス数に対す
る193nm吸収強度を示した。なお、縦軸の吸収強度
はサンプルの厚さ1cm当りの吸光度(−Log(内部
透過率))で示している。In order to investigate the generation of paramagnetic defects due to ultraviolet irradiation, a part of the above-mentioned transparent quartz glass molded body was cut out, and the boundary surface was polished to form a 10 mm × 10 mm × 40 mm transparent synthetic quartz glass molded body. . The synthetic quartz glass molded body was irradiated with an ArF laser, and changes in the transmittance of light at 193 nm were examined. The irradiation conditions of ArF laser are
Energy density 200 mJ / cm 2 pulse, frequency 1
I went at 00 hertz. FIG. 7 shows the 193 nm absorption intensity with respect to the number of ArF irradiation pulses. The absorption intensity on the vertical axis is represented by the absorbance (-Log (internal transmittance)) per cm thickness of the sample.
【0038】例5.四塩化けい素を蒸留処理して不純物
を除去した後、これを原料として、CVD法で、外径7
0mm、長さ600mmの円柱状の多孔質合成石英ガラ
ス母材を作製した。該多孔質合成石英ガラス母材を、カ
ーボンヒーター仕様の真空炉にいれ、10−5トールま
で真空排気した。この後、ヒーターを昇温し、母材を加
熱した。加熱条件は800℃まで10℃/分で、800
乃至1400℃では1℃/分の昇温速度で加熱し、14
00℃に達した時点で加熱を停止し、自然冷却した。外
径50mm,長さ550mmの円柱状の透明合成石英ガ
ラスが得られた。得られた透明ガラスのOH含有率は約
15ppmであった。Example 5. After removing impurities by distilling silicon tetrachloride, using this as a raw material, the outer diameter of 7
A cylindrical porous synthetic quartz glass base material having a length of 0 mm and a length of 600 mm was produced. The porous synthetic quartz glass base material was placed in a vacuum furnace with a carbon heater specification and evacuated to 10 −5 torr. After that, the heater was heated to heat the base material. Heating condition is 800 ℃, 10 ℃ / min, 800
To 1400 ° C., heating at a heating rate of 1 ° C./min.
When the temperature reached 00 ° C, the heating was stopped and the mixture was naturally cooled. A cylindrical transparent synthetic quartz glass having an outer diameter of 50 mm and a length of 550 mm was obtained. The OH content of the obtained transparent glass was about 15 ppm.
【0039】該円柱状透明合成石英ガラスを、例4と同
様の方法で均質化し、しかるのち、該透明石英ガラス部
分を切り出し、カーボンヒーター仕様の加熱炉で成形
し、外径120mm、長さ80mmの円柱状の合成石英
ガラス成形体を得た。この時の成形温度は約1700℃
で、窒素ガス雰囲気中で行った。該合成石英ガラス成形
体を、その歪み取りのためのアニール熱処理を行った。
アニール熱処理条件は、1100℃まで昇温したのち、
0.2℃/分の降温速度で600℃まで降温した。熱処
理は大気中の雰囲気で行った。得られた合成石英ガラス
成形体の複屈折は、2nm/cm以下であり、屈折率分
布も実質上均一であり、屈折率の最大値と最小値の差
(Δn)は、0.8×10−6であった。本例の合成石
英ガラスについて、例4と同様の条件でArFレーザー
を照射して、193nmの光の透過率の変化を調べた。
その結果を纏めて図7に示した。The cylindrical transparent synthetic quartz glass was homogenized in the same manner as in Example 4, and then the transparent quartz glass portion was cut out and molded in a heating furnace with a carbon heater specification, an outer diameter of 120 mm and a length of 80 mm. A cylindrical synthetic quartz glass molded body of was obtained. Molding temperature at this time is about 1700 ℃
In a nitrogen gas atmosphere. The synthetic quartz glass molded body was annealed and heat treated to remove its distortion.
The annealing heat treatment conditions are as follows:
The temperature was lowered to 600 ° C. at a rate of 0.2 ° C./min. The heat treatment was performed in the atmosphere. The birefringence of the obtained synthetic quartz glass molded body is 2 nm / cm or less, the refractive index distribution is substantially uniform, and the difference (Δn) between the maximum value and the minimum value of the refractive index is 0.8 × 10. It was -6 . The synthetic quartz glass of this example was irradiated with an ArF laser under the same conditions as in Example 4, and the change in the transmittance of 193 nm light was examined.
The results are shown together in FIG. 7.
【0040】比較例3.上記例4の場合と同様にして作
製した多孔質合成石英ガラス母材を、カーボン仕様の炉
にいれ、Heガス雰囲気中で透明ガラス化した。加熱条
件は、1600℃まで10℃/分の割合で昇温し、16
00℃に達した時点で加熱を停止して、自然冷却した。
得られた透明合成石英ガラスのOH含有率は約300p
pmであった。しかるのち、例1と同じ条件で、均質化
工程、成形工程、アニール工程の処理を施した。複屈折
及び屈折率分布は、例1の合成石英ガラスの場合とほぼ
同じであった。本例の合成石英ガラスについて、例4と
同様の条件でArFレーザーを照射して、193nmの
光の透過率の変化を調べた。その結果をまとめて図7に
示した。Comparative Example 3. The porous synthetic quartz glass base material produced in the same manner as in the case of the above-mentioned Example 4 was put in a furnace with carbon specifications to be transparent vitrified in a He gas atmosphere. The heating condition is that the temperature is raised to 1600 ° C. at a rate of 10 ° C./minute,
When the temperature reached 00 ° C, the heating was stopped and the mixture was naturally cooled.
The obtained transparent synthetic quartz glass has an OH content of about 300 p.
It was pm. Then, under the same conditions as in Example 1, a homogenizing step, a molding step, and an annealing step were performed. The birefringence and the refractive index distribution were almost the same as in the case of the synthetic quartz glass of Example 1. The synthetic quartz glass of this example was irradiated with an ArF laser under the same conditions as in Example 4, and the change in the transmittance of 193 nm light was examined. The results are shown together in FIG.
【0041】比較例4.一般的に用いられている光学用
の合成石英ガラス成形体について、上記例1と同様の条
件でArFレーザーを照射し、評価した。これは、四塩
化けい素を直接火炎加水分解法(酸素・水素火炎による
ダイレクト法)により合成した合成石英ガラスである。
このガラスのOH含有率は約900ppmであった。こ
の合成石英ガラスに例1と同じ条件で、均質化工程、成
形工程、アニール工程の処理を施した。得られた合成石
英ガラス成形体の複屈折及び屈折率分布は、例1の合成
石英ガラスの場合とほぼ同じであった。また、合成石英
ガラス中の残留水素分子の水素分子濃度を、ラマン散乱
法で測定したところ、3×1016分子数/cm3であ
った。本例の合成石英ガラスいついて例4と同様の条件
でArFレーザーを照射して、193nmの光の透過率
の変化を調べた。その結果を例4及び例5と共に、纏め
て図7に示した。Comparative Example 4. A synthetic quartz glass molding for optics, which is generally used, was irradiated with an ArF laser under the same conditions as in Example 1 above and evaluated. This is a synthetic quartz glass obtained by synthesizing silicon tetrachloride by a direct flame hydrolysis method (a direct method using an oxygen / hydrogen flame).
The OH content of this glass was about 900 ppm. The synthetic quartz glass was subjected to a homogenizing step, a forming step and an annealing step under the same conditions as in Example 1. The birefringence and refractive index distribution of the obtained synthetic quartz glass molded body were almost the same as those of the synthetic quartz glass of Example 1. Further, the hydrogen molecule concentration of residual hydrogen molecules in the synthetic quartz glass was measured by Raman scattering method and found to be 3 × 10 16 molecules / cm 3 . The synthetic quartz glass of this example was irradiated with an ArF laser under the same conditions as in Example 4, and the change in the transmittance of 193 nm light was examined. The results are collectively shown in FIG. 7 together with Example 4 and Example 5.
【0042】例4及び5と比較例3及び4とでは、複屈
折、及び屈折率分布は、ほぼ同じ値を示した。しかしな
がら、ArFレーザー照射に対する耐性は図7の結果に
示されるように、例4及び5の場合、吸光度の増加がみ
られ、他の比較例3及び4と較べて著しく抑制されてい
る。特に比較例4と較べた場合、例4及び5の吸光度の
増加は約4分の1に抑制されている。これは、例4及び
例5の光学部材が、ArFレーザー照射にともなって生
成する常磁性欠陥の生成量が低いこと、及び真空雰囲気
での透明ガラス化処理に依ってよりエキシマレーザー光
の照射に対して安定なガラスが作製できることを示して
いる。In Examples 4 and 5 and Comparative Examples 3 and 4, the birefringence and the refractive index distribution showed almost the same value. However, as shown in the results of FIG. 7, the resistance to ArF laser irradiation increased the absorbance in Examples 4 and 5, and was significantly suppressed as compared with the other Comparative Examples 3 and 4. Especially when compared with Comparative Example 4, the increase in absorbance of Examples 4 and 5 was suppressed to about 1/4. This is because the optical members of Examples 4 and 5 have a low production amount of paramagnetic defects generated by ArF laser irradiation, and are more susceptible to excimer laser light irradiation due to transparent vitrification treatment in a vacuum atmosphere. On the other hand, it shows that stable glass can be produced.
【0043】これらの実施例及び比較例において、水素
分子濃度は、比較例4を除いて1×1016分子数/c
m3であった。屈折率の分布Δnは、例2で1×10
−6であり、比較例1は1×10−6、比較例2は5×
10−6であった。塩素濃度は、例4及び例5並びに比
較例3で、何れも10ppmであるが、比較例4では8
0ppmであった。In these Examples and Comparative Examples, the hydrogen molecule concentration was 1 × 10 16 molecules / c except for Comparative Example 4.
It was m 3 . The refractive index distribution Δn is 1 × 10 in Example 2.
-6 , Comparative Example 1 is 1 × 10 −6 , Comparative Example 2 is 5 ×
It was 10 −6 . The chlorine concentration is 10 ppm in each of Examples 4 and 5 and Comparative Example 3, but is 8 in Comparative Example 4.
It was 0 ppm.
【0044】[0044]
【発明の効果】本発明による合成石英ガラス光学部材
は、OH基の含有率が10乃至100ppm、塩素の含
有率が200ppm以下、Δnで5×10−6の屈折率
分布の均質性及び5nm/cm以下の複屈折を有するも
のであるので、従来の合成石英ガラス光学部材に比較し
て、長時間のエキシマレーザー光の照射下において、光
の透過率が低下することなく使用できることとなり、例
えば、半導体のリソグラフィ装置において、長時間の使
用が可能となり、光学部材を交換する回数を減らして、
安定した露光を行うことができ、半導体リソグラフィの
処理効率を向上することができる。また、本発明による
エキシマレーザー用合成石英ガラス光学部材は、その光
透過面における屈折率の分布Δnが、5×10−6以下
となっているので、従来の合成石英ガラス光学部材で
は、達成できなかったエキシマレーザー光の照射下にお
ける、光学部材全体に渡っての均一な紫外レーザーの透
過を行うことができることとなり、例えば、半導体リソ
グラフィ装置において、長時間に亙って均一な露光を行
うことができ、半導体リソグラフィの歩留まりの向上を
はかることができる。Industrial Applicability The synthetic quartz glass optical member according to the present invention has an OH group content of 10 to 100 ppm, a chlorine content of 200 ppm or less, a homogeneity of a refractive index distribution of 5 × 10 −6 in Δn and 5 nm / n. Since it has a birefringence of not more than cm, it can be used without a decrease in light transmittance under irradiation of excimer laser light for a long time as compared with a conventional synthetic silica glass optical member. In semiconductor lithographic apparatus, it can be used for a long time, reducing the number of times to replace optical members,
Stable exposure can be performed, and the processing efficiency of semiconductor lithography can be improved. Further, the synthetic quartz glass optical member for excimer laser according to the present invention has a refractive index distribution Δn of 5 × 10 −6 or less on the light transmitting surface thereof, and therefore can be achieved by the conventional synthetic quartz glass optical member. It was possible to perform uniform UV laser transmission over the entire optical member under the irradiation of excimer laser light, which was not possible, for example, in a semiconductor lithography apparatus, it is possible to perform uniform exposure for a long time. Therefore, the yield of semiconductor lithography can be improved.
【0045】本発明においては、高純度四塩化けい素等
の高純度揮発性けい素化合物を、酸水素炎により火炎加
水分解し、この分解により生成する微粒子シリカを耐熱
性基体上に堆積させてシリカガラスの多孔質母材を製造
し、該シリカガラスの多孔質母材を1×10−2トール
以上の高真空度で加熱して、透明な石英ガラスを形成
し、該透明石英ガラスを均質化処理することにより、少
なくとも一方向に脈理を有しない高均質石英ガラスを形
成し、該高均質石英ガラスを成形後アニール処理するの
で、従来の製法によるエキシマレーザー用石英ガラス部
材と比較して、不純物の混入を極力抑えることができ、
かつ、ガラスの固有欠陥濃度の低いガラスを作成するこ
とができる。その結果、本発明によると、従来の方法に
比して、エキシマレーザー光の照射に対して、常磁性欠
陥の生成を抑制することができ、耐エキシマレーザー性
の優れた石英ガラスが得られる。In the present invention, a high-purity volatile silicon compound such as high-purity silicon tetrachloride is subjected to flame hydrolysis by an oxyhydrogen flame, and fine particle silica produced by this decomposition is deposited on a heat-resistant substrate. A porous base material of silica glass is manufactured, and the porous base material of silica glass is heated at a high vacuum degree of 1 × 10 −2 Torr or more to form transparent quartz glass, and the transparent quartz glass is homogenized. By the chemical treatment, a highly homogeneous quartz glass having no striae in at least one direction is formed, and since the highly homogeneous quartz glass is annealed after being molded, compared with a conventional production method of the excimer laser quartz glass member. It is possible to suppress the mixture of impurities as much as possible,
In addition, it is possible to produce glass having a low intrinsic defect concentration of glass. As a result, according to the present invention, as compared with the conventional method, it is possible to suppress the generation of paramagnetic defects due to the irradiation of excimer laser light, and it is possible to obtain quartz glass having excellent excimer laser resistance.
図1は、本発明の実施例1の光学窓用合成石英ガラス成
形体について、厚さ10mmの試料についての紫外線領
域における透過率曲線を示す図である。図2は、本発明
の実施例1及び比較例1の光学窓用合成石英ガラス成形
体についての波長248nmにおける吸光度変化を示す
図である。図3は、本発明の実施例3の光学窓用合成石
英ガラス成形体についての屈折率分布を示す干渉縞を示
す図である。図4は、本発明の実施例3の光学窓用合成
石英ガラス成形体の中央部及び外周部について波長24
8nmにおける吸光度変化を示す図である。図5は、比
較例2の光学窓用合成石英ガラス成形体について、厚さ
1.0cmの試料についての紫外線領域における透過率
曲線を示す図である。図6は、実施例1及び比較例2の
光学窓用合成石英ガラス成形体についての波長248n
mにおける吸光度変化を示す図である。図7は、本発明
の実施例4及び5並びに比較例3及び4におけるArF
レーザ照射パルス数に対する193nmの光の吸収曲線
を示す図である。FIG. 1 is a diagram showing a transmittance curve in an ultraviolet region of a 10 mm-thick sample of the synthetic quartz glass molding for an optical window of Example 1 of the present invention. FIG. 2 is a diagram showing changes in absorbance at a wavelength of 248 nm for the synthetic quartz glass molded bodies for optical windows of Example 1 and Comparative Example 1 of the present invention. FIG. 3 is a view showing interference fringes showing a refractive index distribution of a synthetic quartz glass molded body for an optical window of Example 3 of the present invention. FIG. 4 shows the wavelength 24 for the central portion and the outer peripheral portion of the synthetic quartz glass molded body for an optical window of Example 3 of the present invention.
It is a figure which shows the light absorbency change in 8 nm. FIG. 5 is a diagram showing a transmittance curve in an ultraviolet region of a 1.0 cm-thick sample of the synthetic quartz glass molded product for an optical window of Comparative Example 2. FIG. 6 shows a wavelength of 248 n for the synthetic quartz glass molded bodies for optical windows of Example 1 and Comparative Example 2.
It is a figure which shows the light absorbency change in m. FIG. 7 shows ArF in Examples 4 and 5 of the present invention and Comparative Examples 3 and 4.
It is a figure which shows the absorption curve of the light of 193 nm with respect to a laser irradiation pulse number.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 稲木 恭一 福島県郡山市田村町金屋字川久保88 信越 石英株式会社石英技術研究所内 (72)発明者 加藤 俊幸 福島県郡山市田村町金屋字川久保88 信越 石英株式会社郡山工場内 (72)発明者 嶋田 敦之 福島県郡山市田村町金屋字川久保88 信越 石英株式会社郡山工場内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoichi Inagi Kanayama, Tamura-cho, Koriyama-shi, Fukushima 88 Kawakubo, Shin-Etsu Quartz Co., Ltd. (72) Toshiyuki Kato Kawakubo, Kawamura, Tamura-cho, Koriyama, Fukushima 88 Shin-Etsu Quartz Co., Ltd.Koriyama Plant (72) Inventor Atsushi Shimada 88 Kawakubo, Kanaya, Tamura-cho, Koriyama City, Fukushima Prefecture Shin-Etsu Quartz Co., Ltd., Koriyama Plant
Claims (7)
学部材において、10乃至100ppmのOH基の含有
率、200ppm以下の塩素の含有率、1×1016分
子数/cm3以下の水素分子含有率、Δnで5×10
−6以下の屈折率分布の均質性及び5nm/cm以下の
複屈折を有することを特徴とする合成石英ガラス製のエ
キシマレーザー用光学部材。1. An excimer laser optical member made of synthetic quartz glass, having an OH group content of 10 to 100 ppm, a chlorine content of 200 ppm or less, and a hydrogen molecule content of 1 × 10 16 molecules / cm 3 or less. , Δn is 5 × 10
An optical member for excimer laser made of synthetic silica glass, which has a homogeneity of a refractive index distribution of -6 or less and a birefringence of 5 nm / cm or less.
率が99%以上であることを特徴とする請求の範囲1に
記載のエキシマレーザー用合成石英ガラス光学部材。2. The synthetic quartz glass optical member for an excimer laser according to claim 1, which has an internal transmittance of 99% or more for light having a wavelength of 245 nm.
光学部材が、波長300nm以下のエキシマレーザー用
窓、鏡、レンズ及びプリズムであることを特徴とする請
求の範囲1に記載の合成石英ガラス製のエキシマレーザ
ー用光学部材。3. The excimer made of synthetic quartz glass according to claim 1, wherein the synthetic quartz glass optical member for excimer laser is a window, a mirror, a lens and a prism for excimer laser having a wavelength of 300 nm or less. Optical member for laser.
炎加水分解し、生成する微粒子シリカを耐熱性基体上に
堆積させて多孔質シリカ母材を製造し、該多孔質シリカ
母材を1×10−2トール以上の高真空度下で1400
℃以上の温度に加熱して、脱水及び脱ガスを行い、次い
で、この脱水及び脱ガスされた透明な石英ガラスを均質
化処理することにより、少なくとも一方向に脈理を有し
ない高均質石英ガラスを形成し、次いでこの得られた該
高均質石英ガラスを成形し、成形された高均質石英ガラ
スをアニール処理することを特徴とする、10乃至10
0ppmのOH基の含有率、200ppm以下の塩素の
含有率、1×1016分子数/cm3以下の水素分子含
有率、Δnで5×10−6以下の屈折率分布の均質性及
び5nm/cm以下の複屈折を有する合成石英ガラス製
のエキシマレーザー用光学部材の製造方法。4. A volatile silicon compound is flame-hydrolyzed by an oxyhydrogen flame, and the resulting fine particle silica is deposited on a heat-resistant substrate to produce a porous silica base material. 1400 under high vacuum of 1 × 10 -2 Torr or more
Highly homogeneous quartz glass having no striae in at least one direction by heating to a temperature of ℃ or higher to dehydrate and degas, and then subjecting the dehydrated and degassed transparent quartz glass to homogenization treatment. And then forming the obtained high-homogeneous quartz glass, and annealing the formed high-homogeneous quartz glass.
OH group content of 0 ppm, chlorine content of 200 ppm or less, hydrogen molecule content of 1 × 10 16 molecules / cm 3 or less, homogeneity of refractive index distribution of Δn of 5 × 10 −6 or less, and 5 nm / A method of manufacturing an optical member for excimer laser made of synthetic silica glass having a birefringence of not more than cm.
上の温度で行われることを特徴とする請求の範囲5に記
載の合成石英ガラス製のエキシマレーザー用光学部材の
製造方法。5. The method for producing an optical member for excimer laser made of synthetic quartz glass according to claim 5, wherein the homogenizing treatment of the quartz glass is performed at a temperature of 1600 ° C. or higher.
以上の温度で行われることを特徴とする請求の範囲5に
記載のエキシマレーザー用石英ガラス光学部材の製造方
法。6. The molding of highly homogeneous quartz glass is 1500 ° C.
The method for producing a silica glass optical member for excimer laser according to claim 5, wherein the method is performed at the above temperature.
の温度範囲の温度下で行われることを特徴とする請求の
範囲5に記載の合成石英ガラス製のエキシマレーザー用
光学部材の製造方法。7. The annealing treatment is 800 ° C. to 1250 ° C.
The method for producing an optical member for excimer laser made of synthetic quartz glass according to claim 5, wherein the method is performed under a temperature range of
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JP4210622A JP2879500B2 (en) | 1992-06-29 | 1992-06-29 | Synthetic quartz glass optical member for excimer laser and method of manufacturing the same |
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JP4210622A JP2879500B2 (en) | 1992-06-29 | 1992-06-29 | Synthetic quartz glass optical member for excimer laser and method of manufacturing the same |
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JPH0616449A true JPH0616449A (en) | 1994-01-25 |
JP2879500B2 JP2879500B2 (en) | 1999-04-05 |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06227827A (en) * | 1992-02-07 | 1994-08-16 | Asahi Glass Co Ltd | Transparent silica glass and its production |
US5736111A (en) * | 1995-07-31 | 1998-04-07 | Sumitomo Chemical Company, Limited | Method for producing iron-containing complex oxide powders |
EP0879799A3 (en) * | 1997-05-16 | 1999-07-21 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
US6333283B1 (en) | 1997-05-16 | 2001-12-25 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
EP1327613A1 (en) * | 2001-12-06 | 2003-07-16 | Heraeus Quarzglas GmbH & Co. KG | Quartz glass blank for preparing an optical component and its application |
EP1586544A1 (en) * | 2004-04-02 | 2005-10-19 | Heraeus Quarzglas GmbH & Co. KG | Optical element made from silica glass, method of its manufacture and its use |
WO2006080241A2 (en) * | 2005-01-25 | 2006-08-03 | Asahi Glass Company, Limited | PROCESS FOR PRODUCING SILICA GLASS CONTAINING TiO2, AND OPTICAL MATERIAL FOR EUV LITHOGRAPHY EMPLOYING SILICA GLASS CONTAINING TiO2 |
JP2006242741A (en) * | 2005-03-03 | 2006-09-14 | Tohoku Univ | Manufacturing method of standard sample for calibrating characteristic analyzer of ultrasonic material with respect to material having stria |
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DE10392340T5 (en) * | 2002-03-05 | 2005-04-07 | Corning Incorporated | Optical elements and methods for predicting the performance of an optical element and optical system |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0388743A (en) * | 1989-06-19 | 1991-04-15 | Shinetsu Sekiei Kk | Synthetic silica glass optical body for ultraviolet laser and production therefor |
-
1992
- 1992-06-29 JP JP4210622A patent/JP2879500B2/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0388743A (en) * | 1989-06-19 | 1991-04-15 | Shinetsu Sekiei Kk | Synthetic silica glass optical body for ultraviolet laser and production therefor |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06227827A (en) * | 1992-02-07 | 1994-08-16 | Asahi Glass Co Ltd | Transparent silica glass and its production |
US5736111A (en) * | 1995-07-31 | 1998-04-07 | Sumitomo Chemical Company, Limited | Method for producing iron-containing complex oxide powders |
EP0879799A3 (en) * | 1997-05-16 | 1999-07-21 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
US5983673A (en) * | 1997-05-16 | 1999-11-16 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
US6333283B1 (en) | 1997-05-16 | 2001-12-25 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
US6709997B2 (en) | 1997-05-16 | 2004-03-23 | Sumitomo Electric Industries, Ltd. | Silica glass article and manufacturing process therefor |
EP1327613A1 (en) * | 2001-12-06 | 2003-07-16 | Heraeus Quarzglas GmbH & Co. KG | Quartz glass blank for preparing an optical component and its application |
EP1586544A1 (en) * | 2004-04-02 | 2005-10-19 | Heraeus Quarzglas GmbH & Co. KG | Optical element made from silica glass, method of its manufacture and its use |
WO2006080241A2 (en) * | 2005-01-25 | 2006-08-03 | Asahi Glass Company, Limited | PROCESS FOR PRODUCING SILICA GLASS CONTAINING TiO2, AND OPTICAL MATERIAL FOR EUV LITHOGRAPHY EMPLOYING SILICA GLASS CONTAINING TiO2 |
WO2006080241A3 (en) * | 2005-01-25 | 2006-09-21 | Asahi Glass Co Ltd | PROCESS FOR PRODUCING SILICA GLASS CONTAINING TiO2, AND OPTICAL MATERIAL FOR EUV LITHOGRAPHY EMPLOYING SILICA GLASS CONTAINING TiO2 |
JP2006242741A (en) * | 2005-03-03 | 2006-09-14 | Tohoku Univ | Manufacturing method of standard sample for calibrating characteristic analyzer of ultrasonic material with respect to material having stria |
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