JP2001048571A - Quartz glass excellent in transmission of short wavelength light, and its production - Google Patents
Quartz glass excellent in transmission of short wavelength light, and its productionInfo
- Publication number
- JP2001048571A JP2001048571A JP2000158606A JP2000158606A JP2001048571A JP 2001048571 A JP2001048571 A JP 2001048571A JP 2000158606 A JP2000158606 A JP 2000158606A JP 2000158606 A JP2000158606 A JP 2000158606A JP 2001048571 A JP2001048571 A JP 2001048571A
- Authority
- JP
- Japan
- Prior art keywords
- quartz glass
- less
- ppm
- content
- wavelength
- 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
- 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
- C03B2201/08—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
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/21—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with molecular hydrogen
Abstract
Description
【０００１】[0001]
【発明が属する技術分野】本発明は集積回路のリソグラ
フィーなどに用いられる、短波長の紫外線領域における
光の透過性にすぐれた合成石英ガラスに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic quartz glass which is used for lithography of integrated circuits and has excellent light transmittance in a short wavelength ultraviolet region.
【０００２】[0002]
【従来の技術】集積回路をシリコンウエハなどの基板上
に形成させるための、電子回路パターン描像をおこなう
リソグラフィーに使用される露光用の光は、集積回路が
高密度化精細化して行くにつれて、次第に短波長側に移
行しつつある。従来、このリソグラフィーの露光に用い
られていた光は、水銀燈の輝線のｇ線（波長435nm）や
ｉ線（波長365nm）であった。露光の分解能は波長に比
例して短波長ほど向上するので、これらの光では精細化
への対応に限界がある。これに対し、高エネルギーの短
波長の単色光が得られることから、水銀燈に代わってＡ
ｒＦ（波長193nm）やＸｅ2（波長172nm）などのエキシ
マレーザーの光の適用の実用化が進められている。2. Description of the Related Art Exposure light used in lithography for forming an electronic circuit pattern for forming an integrated circuit on a substrate such as a silicon wafer is gradually increased as integrated circuits become denser and finer. It is shifting to the shorter wavelength side. Conventionally, light used for this lithography exposure is a g-line (wavelength of 435 nm) or an i-line (wavelength of 365 nm) of a mercury lamp. Since the resolution of the exposure is improved in proportion to the wavelength in proportion to the wavelength, the resolution of such light is limited. On the other hand, since high-energy short-wavelength monochromatic light can be obtained, A
Practical use of excimer laser light such as rF (wavelength 193 nm) and Xe 2 (wavelength 172 nm) is being promoted.
【０００３】波長約400nm以下の紫外域の光に対し透過
率のよい光学材料として石英ガラスがあり、ランプ、レ
ンズ、プリズム、ＩＣパターン用マスクなどに用いられ
ているが、200nm以下の短波長にもなると光の透過率は
大きく低下してくる。透過率の低下は、単に露光時間を
増大させるだけではなく、光学材料が発熱して変形や屈
折率の変化を生じて、マスクなどでは回路パターンのひ
ずみが増し、材質変化も発生してさらなる透過性低下を
来す。このため、短波長のエキシマレーザ光の活用に
は、そのような短波長領域の光に対して透過率の十分す
ぐれた材料が必要である。[0003] Quartz glass is an optical material having a high transmittance for ultraviolet light having a wavelength of about 400 nm or less, and is used for lamps, lenses, prisms, masks for IC patterns, and the like. When this happens, the light transmittance is greatly reduced. The decrease in transmittance does not merely increase the exposure time, but also causes the optical material to generate heat, causing deformation and a change in the refractive index. Sexual decline occurs. For this reason, in order to utilize the short-wavelength excimer laser light, it is necessary to use a material having a sufficiently high transmittance for light in such a short-wavelength region.
【０００４】石英ガラスの製造には、天然の水晶を原料
として加熱溶融する方法があるが、微量不純物の混入は
避け難く、これら不純物の含有は紫外光の吸収を増大さ
せる。したがって、紫外域の光に用いて光学的性能が要
求される場合、四塩化珪素のような珪素化合物を蒸留な
どの方法で精製高純度化し、これを高温で分解酸化して
得るきわめて不純物の少ない石英ガラスとするのが普通
である。天然原料をそのまま溶融する場合を溶融石英ガ
ラスというのに対し、一旦塩化物などの珪素化合物にし
て精製後、再度酸化して製造する場合を合成石英ガラス
という。For the production of quartz glass, there is a method in which natural quartz is heated and melted as a raw material. However, the incorporation of trace impurities is inevitable, and the inclusion of these impurities increases the absorption of ultraviolet light. Therefore, when optical performance is required using light in the ultraviolet region, a silicon compound such as silicon tetrachloride is purified and purified to a high degree by a method such as distillation, and is extremely low in impurities obtained by decomposing and oxidizing the compound at a high temperature. Usually, it is quartz glass. Where the natural raw material is melted as it is, it is called fused silica glass. On the other hand, when it is once made into a silicon compound such as chloride and then purified and then oxidized again, it is called synthetic quartz glass.
【０００５】合成石英ガラスの製造には、原料の珪素化
合物を酸素水素炎や炭化水素酸素炎にて高温に加熱し酸
化してできた石英を、そのまま溶融してガラスを得る直
接法、高温の高周波酸素プラズマ中で分解酸化して石英
ガラスとするプラズマ法、一旦火炎中で加水分解してで
きたＳｉＯ2微粒子を堆積させて、多孔質の不透明石英
の堆積物（スート体）を作り、これを再加熱して溶融透
明化するいわゆるスート法などがある。[0005] In the production of synthetic quartz glass, a direct method of directly melting glass obtained by heating and oxidizing a silicon compound as a raw material at a high temperature with an oxyhydrogen flame or a hydrocarbon oxygen flame to obtain glass, A plasma method that decomposes and oxidizes in high-frequency oxygen plasma to form quartz glass, deposits SiO 2 fine particles that are once hydrolyzed in a flame, and forms a porous opaque quartz deposit (soot body). Is soot melted to make it transparent.
【０００６】スート法では、高純度原料を用いれば製品
はほとんど汚染されることがなく、加熱され透明にされ
る前に、多孔質の状態を経るので、多孔質を種々の雰囲
気で処理することにより、純化やドーピングなどによる
改質も可能である。この過程で、紫外線吸収ばかりでな
く、石英ガラスの耐熱性に大きく影響するＯＨ基濃度
も、ある程度任意に制御できる。したがって、前述の紫
外線の短波長領域における透過率向上に対し、この方法
を基に種々改善を行うことが、他の製造方法によるより
も好ましいと考えられる。[0006] In the soot method, if a high-purity raw material is used, the product is hardly contaminated and passes through a porous state before being heated and made transparent. Thus, modification by purification, doping, or the like is also possible. In this process, not only the absorption of ultraviolet rays but also the OH group concentration, which greatly affects the heat resistance of quartz glass, can be arbitrarily controlled to some extent. Therefore, it is considered that it is preferable to make various improvements based on this method to improve the transmittance of the ultraviolet light in the short wavelength region as compared with other manufacturing methods.
【０００７】たとえば特開平6-183752号公報には、多孔
質石英のスート体をヘリウムなど不活性雰囲気中で加熱
透明化する過程で、ＯＨ基を50〜250ppmに制御し、その
後不活性ガス中または真空中にて800〜2000℃で加熱処
理することによる、波長300nm以下の紫外線照射で吸収
帯がなく赤外線発光もない合成石英の発明が提示されて
いるが、透過率の具体的な値は示されていない。[0007] For example, Japanese Patent Application Laid-Open No. 6-183752 discloses that in the process of heating a porous quartz soot body in an inert atmosphere such as helium to make it transparent, the OH group is controlled to 50 to 250 ppm, Or by heat treatment in vacuum at 800 ~ 2000 ℃, the invention of synthetic quartz without absorption band and no infrared emission by ultraviolet irradiation of wavelength 300nm or less has been proposed, but the specific value of transmittance is Not shown.
【０００８】また特開平9-235134号公報には、光リソグ
ラフィなどに用いる波長165〜195nmの遠紫外線の照射に
対し透過率が高く屈折率変化の少ない、ＯＨ基濃度が10
〜400ppmで酸素欠損型欠陥濃度、二酸化炭素放出量、水
蒸気放出量などを限定した石英ガラスの発明が開示され
ている。この石英ガラスを得る手段は、まず珪素化合物
の火炎加水分解でＯＨ基を上記範囲に制御したスート体
を作り、これを100Pa以下の真空下で1300〜1700℃にて
帯溶融して透明化し、さらに脱ガス処理や、遠紫外線照
射によるダメージ修復を目的に水素ドープ処理をおこな
う。しかし、波長172nmのＸｅ2エキシマレーザ光の1cm
あたりの透過率は80％程度までである。Japanese Patent Application Laid-Open No. 9-235134 discloses that, when irradiated with far ultraviolet rays having a wavelength of 165 to 195 nm used for photolithography or the like, the transmittance is high, the refractive index change is small, and the OH group concentration is 10%.
An invention of quartz glass in which the concentration of oxygen-deficient defects, the amount of released carbon dioxide, and the amount of released water vapor are limited to 400 ppm is disclosed. Means of obtaining this quartz glass is to first make a soot body in which the OH group is controlled to the above range by flame hydrolysis of a silicon compound, and to melt and clarify this at 1300 to 1700 ° C. under a vacuum of 100 Pa or less, Further, a hydrogen doping process is performed for the purpose of degassing and repairing damage due to irradiation with far ultraviolet rays. However, 1 cm of Xe 2 excimer laser light having a wavelength of 172 nm is used.
The transmittance per unit is up to about 80%.
【０００９】このような改良により、合成石英ガラスの
200nm以下の遠紫外領域における透過率は向上しつつあ
るがまだ十分ではなく、より一層の向上が必要である。With such improvements, synthetic quartz glass
The transmittance in the far ultraviolet region of 200 nm or less is improving, but not yet sufficient, and further improvement is required.
【００１０】[0010]
【発明が解決しようとする課題】本発明の目的は、Ａｒ
Ｆ（波長193nm）、Ｘｅ2（波長172nm）などのエキシマ
レーザー等による遠紫外域の光源を用いてシリコンウェ
ーハなどに電子回路の集積パターンを描像する光リソグ
ラフィーの、光学系やマスクの基材に適用される、とく
に波長が165〜200nmの範囲の遠紫外領域にて、光の透過
率が1cmあたり85％以上の石英ガラスの提供にある。SUMMARY OF THE INVENTION The object of the present invention is
F (wavelength 193 nm), photolithography for imaged integrated pattern of an electronic circuit, such as a silicon wafer using a far ultraviolet region of the light source by an excimer laser or the like, such as Xe 2 (wavelength 172 nm), the base material of the optical system and the mask It is an object of the present invention to provide quartz glass having a light transmittance of 85% or more per cm, particularly in the deep ultraviolet region having a wavelength in the range of 165 to 200 nm.
【００１１】[0011]
【課題を解決するための手段】より短波長の光に適用さ
れる石英ガラスとしては、使用する光の波長域での透過
率ができるだけ大きいことが好ましい。天然原料による
溶融石英中にて多く見られるアルカリ金属元素Ｌｉ、Ｎ
ａ、Ｋ、およびアルカリ土類金属元素Ｍｇ、Ｃａ、ある
いは３ｄ遷移金属元素のＴｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、
Ｃｏ、ＮｉおよびＣｕなどの微量不純物は、遠紫外域の
光の吸収を増したり、紫外線照射による発光の原因とな
るので、できるだけ低減する必要がある。As quartz glass applied to light of shorter wavelength, it is preferable that the transmittance of the used light in the wavelength region is as large as possible. Alkali metal elements Li, N often found in fused quartz from natural raw materials
a, K, and alkaline earth metal elements Mg, Ca, or 3d transition metal elements Ti, V, Cr, Mn, Fe,
Trace impurities such as Co, Ni, and Cu increase the absorption of light in the far ultraviolet region or cause light emission by ultraviolet irradiation, and thus need to be reduced as much as possible.
【００１２】一方、ＳｉＣｌ4やＳｉＣｌ3（ＣＨ3）な
ど低沸点の珪素化合物を原料とし、酸素水素炎などにて
加水分解酸化させて得る合成石英ガラスでは、原料の蒸
留精製により十分に不純物を除去できるため、これら不
純物元素の含有はきわめて少なくすることができる。そ
こで、酸素水素火炎中の加水分解反応によりできたＳｉ
Ｏ2微粒子を堆積させて多孔質の不透明石英のスート体
を作り、これを再加熱して溶融透明化するＶＡＤ法（Va
por-phase Axial Deposition法）により作製した合成石
英ガラスで、極微量に残存したこれら不純物元素の含有
量の影響を調べてみた。On the other hand, in a synthetic quartz glass obtained by using a low-boiling silicon compound such as SiCl 4 or SiCl 3 (CH 3 ) as a raw material and hydrolyzing and oxidizing it with an oxygen-hydrogen flame or the like, impurities can be sufficiently removed by distillation and purification of the raw material. Since they can be removed, the content of these impurity elements can be extremely reduced. Therefore, Si formed by the hydrolysis reaction in the oxygen-hydrogen flame
A VAD method (Va method) in which a porous opaque quartz soot body is made by depositing O 2 fine particles and then reheated to make it transparent.
The influence of the content of these impurity elements remaining in trace amounts on synthetic quartz glass produced by the por-phase axial deposition method was examined.
【００１３】その結果、個々の元素の含有量を限定する
よりは、Ｌｉ、Ｎａ、Ｋ、ＭｇおよびＣａについては、
これらの元素の合計量をできるだけ低減すること、そし
てＴｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、ＮｉおよびＣｕ
の合計の含有量も同様に十分低くすることにより、実質
的にこれらの元素の影響はほぼ限界近くまで低減できる
ことがわかった。これら不純物含有量をこのような低レ
ベルに減少させることは、ＶＡＤ法において原料の蒸留
精製を十分おこなえば達成は可能である。As a result, rather than limiting the content of individual elements, for Li, Na, K, Mg and Ca,
To reduce the total amount of these elements as much as possible and to obtain Ti, V, Cr, Mn, Fe, Co, Ni and Cu
It has been found that the effect of these elements can be substantially reduced to almost the limit by setting the total content of the compounds similarly sufficiently low. The reduction of these impurity contents to such a low level can be achieved by sufficiently performing distillation purification of the raw material in the VAD method.
【００１４】次に、得られた石英ガラス中のＯＨ基量の
紫外線透過に及ぼす影響を調べた結果、紫外光域の吸収
端、すなわち吸収率がほぼ0となる波長の最長波長端
は、ＯＨ基濃度の減少とともに短波長側へシフトしてい
き、50ppm以下に低減できれば、165nmの波長にて光路長
1cmあたりの透過率を85％以上は確保できることが明ら
かになった。このような低レベルのＯＨ基濃度は、酸素
水素炎にて加水分解反応ををおこなうとき酸素と水素と
の比率を調整し、さらには、不透明状態のスート体を加
熱して透明化する際の加熱雰囲気を制御することによ
り、達成できることもわかった。Next, as a result of examining the effect of the amount of OH groups in the obtained quartz glass on ultraviolet transmission, the absorption edge in the ultraviolet light range, that is, the longest wavelength end of the wavelength at which the absorptance is almost zero, is OH As the base concentration decreases, the wavelength shifts to the shorter wavelength side, and if it can be reduced to 50 ppm or less, the optical path length at a wavelength of 165 nm
It became clear that a transmittance of 1% or more can be secured to 85% or more. Such a low level of OH group concentration adjusts the ratio of oxygen and hydrogen when performing a hydrolysis reaction in an oxygen-hydrogen flame, and furthermore, when the soot body in an opaque state is heated to be transparent. It was also found that this can be achieved by controlling the heating atmosphere.
【００１５】しかしながら、上述の各不純物含有量をで
きるだけ低減して得られた石英ガラスの遠紫外領域にお
ける透過率を調べていくと、良好ではあるが時には劣る
結果を示すことがある。そこで、その原因について調査
を進めた結果、Ｂ、ＣまたはＮの各元素の含有量もでき
るだけ低下させることにより、165〜200nmにおける透過
率を安定して大きく向上させ得ることが判明した。Ｂ、
ＣまたはＮを低減すればなぜこの短波長域の光の透過性
が向上するのか、その理由は必ずしも明らかではない
が、これらの元素の存在により生じていたガラス内の欠
陥ないしは原子間の歪みが解消され、それによる光の吸
収が低減されたのではないかと思われる。However, when examining the transmittance in the far ultraviolet region of quartz glass obtained by reducing the content of each of the above-mentioned impurities as much as possible, the result may be good but sometimes poor. Therefore, as a result of investigating the cause, it was found that the transmittance in the range of 165 to 200 nm can be stably greatly improved by reducing the content of each element of B, C or N as much as possible. B,
The reason why the transmittance of light in the short wavelength region is improved by reducing C or N is not always clear, but the defect in glass or the distortion between atoms caused by the presence of these elements is reduced. It is considered that the light absorption was reduced and the absorption of light was reduced.
【００１６】これらＢ、ＣまたはＮの軽元素は、原料の
精製によって低減できる一方、至る所に存在するため、
製造過程で容易に混入してくる。そこで、これら元素の
石英ガラス中濃度をより効果的に低減できる方法を種々
検討した結果、合成されたスート体を、減圧下のヘリウ
ムやアルゴンなどの不活性雰囲気中で、まず不透明多孔
質のまま焼結を進行させ、次いで真空下で透明化のため
の高温熱処理をおこなえばよいことが見出された。These light elements of B, C or N can be reduced by refining the raw material, but are present everywhere.
It is easily mixed in the manufacturing process. Therefore, as a result of various studies on methods for more effectively reducing the concentration of these elements in quartz glass, the synthesized soot body was first left opaque and porous in an inert atmosphere such as helium or argon under reduced pressure. It has been found that sintering is allowed to proceed, and then high-temperature heat treatment for clarification is performed under vacuum.
【００１７】気相の化学反応により形成された石英ガラ
スの微粒子が集積したスート体の状態では、雰囲気に曝
されるガラス固体の表面積がきわめて大きい。そして雰
囲気と固体との相互の反応などは高温ほど活発におこな
われる。たとえば、石英中のＢが水素と反応してジボラ
ンになるとかＣがＣＯになって排除されたり、Ｎが雰囲
気の平衡圧に近づき離脱したりする。In a soot body in which fine particles of quartz glass formed by a chemical reaction in a gas phase are accumulated, the surface area of a glass solid exposed to the atmosphere is extremely large. Further, the mutual reaction between the atmosphere and the solid occurs more actively at a higher temperature. For example, B in quartz reacts with hydrogen to become diborane, C becomes CO and is eliminated, or N approaches and approaches the equilibrium pressure of the atmosphere, and desorbs.
【００１８】透明化をおこなうよりもやや低めの高温域
に加熱すると、堆積した石英粒子は焼結して粗大化して
いくが粒子間の隙間はまだ十分大きく、その際に雰囲気
を制御すれば、不純物低減など石英ガラスの組成に容易
に影響をおよぼすことができる。したがって透明化する
前に減圧下の不活性気体や真空と接することにより、
Ｂ、ＣまたはＮが容易に低減できたものと思われる。ま
たこのような減圧処理は、ＯＨ基の濃度を確実に低下さ
せることができ、その上、アルカリ金属元素やアルカリ
土類金属元素のさらなる低減にも効果がある。When heated to a high temperature region slightly lower than that for making transparent, the deposited quartz particles are sintered and coarsened, but the gaps between the particles are still large enough. It can easily affect the composition of quartz glass such as reducing impurities. Therefore, by contacting with an inert gas under reduced pressure or vacuum before clearing,
It seems that B, C or N could be easily reduced. Such reduced pressure treatment can surely lower the concentration of OH groups, and is also effective in further reducing alkali metal elements and alkaline earth metal elements.
【００１９】また、不純物元素やＯＨ基を低減する方法
にハロゲン処理がある。これはスート体に対し、ＦやＣ
ｌなどのハロゲン元素を含む雰囲気中で、上述のように
透明化よりもやや低めの温度域に加熱する処理方法であ
る。この処理をおこなうと不純物はハロゲン化物となっ
て気化し、スート体から排除されるとされている。A halogen treatment is a method for reducing impurity elements and OH groups. This is for soot, F and C
This is a treatment method of heating in an atmosphere containing a halogen element such as 1 to a temperature range slightly lower than the transparency as described above. It is said that when this process is performed, impurities are converted into halides and vaporized, and are eliminated from the soot body.
【００２０】ところがこの方法にて不純物除去を十分お
こなわせようとすると、石英ガラス中にハロゲン元素が
多く含まれるようになり、その結果として酸素欠乏欠陥
によると考えられる、165〜200nmのとくに短波長側の透
過率が大きく低下してくる。しかし不純物の低減効果は
前述の減圧処理によるより遙かに大きいので、この処理
方法を活用することを検討した。その結果、ハロゲン元
素が多く存在していても水素を十分含ませれば、このよ
うな透過率低下は抑制できることが明らかになった。However, in order to sufficiently remove impurities by this method, a large amount of a halogen element is contained in quartz glass, and as a result, it is thought that oxygen deficiency defects cause a short wavelength of 165 to 200 nm. The transmittance on the side greatly decreases. However, since the effect of reducing impurities is far greater than that obtained by the above-described decompression treatment, the use of this treatment method was examined. As a result, it has been found that such a decrease in transmittance can be suppressed if hydrogen is sufficiently contained even when a large amount of a halogen element is present.
【００２１】以上のような知見から、165〜200nmの波長
域の透過率をより大きくする成分や製造条件の限界をさ
らに調査し、本発明に至った。すなわち本発明の要旨は
次の通りである。 (1) 重量比にて、アルカリ金属元素Ｌｉ、Ｎａ、Ｋ、お
よびアルカリ土類金属元素Ｍｇ、Ｃａの合計の含有量が
100ppb以下、３ｄ遷移金属元素Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、
Ｆｅ、Ｃｏ、ＮｉおよびＣｕの合計の含有量が100ppb以
下、Ｂ、ＣまたはＮの含有量のいずれもが1ppm以下で、
さらにＯＨ基の濃度が50ppm以下であることを特徴とす
る波長165〜200nmの光の透過率が光路長1cmあたり85％
以上の合成石英ガラス。 (2) 重量比にて、アルカリ金属元素Ｌｉ、Ｎａ、Ｋ、お
よびアルカリ土類金属元素Ｍｇ、Ｃａの合計の含有量が
100ppb以下、３ｄ遷移金属元素Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、
Ｆｅ、Ｃｏ、ＮｉおよびＣｕの合計の含有量が100ppb以
下、Ｂ、ＣまたはＮの含有量のいずれもが1ppm以下、Ｏ
Ｈ基の濃度が50ppm以下で、ハロゲン元素Ｆ、Ｃｌ、Ｂ
ｒおよびＩの合計の含有量が100〜3000ppm、水素分子の
含有量が1×1017分子/cm3以上であることを特徴とする
波長165〜200nmの光の透過率が光路長1cmあたり85％以
上の合成石英ガラス。 (3) 珪素化合物を火炎中の加水分解反応によりＯＨ基濃
度が500〜1500ppmの多孔質合成石英ガラス体（スート
体）とし、これを500Pa以下の減圧不活性雰囲気下で100
0〜1400℃にて5〜50時間加熱保持し、次いで20Pa以下の
真空中または不活性雰囲気中にて1300〜1600℃で透明化
させることを特徴とする上記(1)の合成石英ガラスの製
造方法。 (4) 珪素化合物を火炎中の加水分解反応によりＯＨ基濃
度が500〜1500ppmの多孔質合成石英ガラス体（スート
体）とし、これをハロゲン元素またはハロゲン化物を含
む雰囲気中で700〜1200℃にて2〜20時間加熱保持するハ
ロゲン処理を施し、次いで不活性雰囲気中または20Pa以
下の真空中にて1300〜1600℃で透明化させることを特徴
とする上記(2)の合成石英ガラスの製造方法。Based on the above findings, the present inventors have further investigated the components for increasing the transmittance in the wavelength range of 165 to 200 nm and the limits of the manufacturing conditions, and have reached the present invention. That is, the gist of the present invention is as follows. (1) By weight ratio, the total content of alkali metal elements Li, Na, K, and alkaline earth metal elements Mg, Ca
100 ppb or less, 3d transition metal elements Ti, V, Cr, Mn,
The total content of Fe, Co, Ni and Cu is 100 ppb or less, and the content of any of B, C or N is 1 ppm or less,
Further, the transmittance of light having a wavelength of 165 to 200 nm is 85% per 1 cm of optical path length, characterized in that the concentration of OH groups is 50 ppm or less.
The above synthetic quartz glass. (2) By weight ratio, the total content of alkali metal elements Li, Na, K, and alkaline earth metal elements Mg, Ca
100 ppb or less, 3d transition metal elements Ti, V, Cr, Mn,
The total content of Fe, Co, Ni and Cu is 100 ppb or less, the content of any of B, C or N is 1 ppm or less.
When the concentration of H group is 50 ppm or less, halogen elements F, Cl, B
wherein the total content of r and I is 100 to 3000 ppm, and the content of hydrogen molecules is 1 × 10 17 molecules / cm 3 or more. % Synthetic quartz glass. (3) A silicon compound is converted into a porous synthetic quartz glass body (soot body) having an OH group concentration of 500 to 1500 ppm by a hydrolysis reaction in a flame, and the resultant is subjected to 100 Pa under a reduced pressure inert atmosphere of 500 Pa or less.
The production of the synthetic quartz glass according to the above (1), wherein the synthetic quartz glass is heated and held at 0 to 1400 ° C. for 5 to 50 hours, and then transparentized at 1300 to 1600 ° C. in a vacuum or an inert atmosphere of 20 Pa or less. Method. (4) A silicon compound is converted into a porous synthetic quartz glass body (soot body) having a OH group concentration of 500 to 1500 ppm by a hydrolysis reaction in a flame, and is heated to 700 to 1200 ° C. in an atmosphere containing a halogen element or a halide. Subjecting to a halogen treatment of heating and holding for 2 to 20 hours, and then making it transparent at 1300 to 1600 ° C. in an inert atmosphere or a vacuum of 20 Pa or less, the method for producing a synthetic quartz glass according to the above (2). .
【００２２】[0022]
【発明の実施の形態】本発明の合成石英ガラス中に含有
されるＬｉ、Ｎａ、Ｋ、ＭｇおよびＣａは、その合計量
が重量比にて100ppb以下とする。これらの元素は、遠紫
外域での吸収に対していずれも同様な影響を及ぼすの
で、個々の量を限定するよりも合計量として取り扱う方
が、吸収の大小の傾向とよく合うからである。これらの
元素は合計量にて100ppb以下であれば、実質的にその影
響は無視できる。BEST MODE FOR CARRYING OUT THE INVENTION The total amount of Li, Na, K, Mg and Ca contained in the synthetic quartz glass of the present invention is not more than 100 ppb by weight. These elements have the same effect on the absorption in the far ultraviolet region, and therefore, it is better to treat them as a total amount rather than limiting the individual amounts, in order to better match the tendency of the absorption. If the total amount of these elements is 100 ppb or less, the effect can be substantially ignored.
【００２３】Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ
およびＣｕの３ｄ遷移金属元素の合計の含有量は重量比
にて100ppb以下とする。これも上記のアルカリ金属元素
およびアルカリ土類金属元素と同様、個々の量を限定す
るより合計量として取り扱う方が紫外線の吸収との対応
がよいからである。100ppb以下に低減すれば、これらの
不純物に基づくと考えられる吸収はほぼ完全になくな
る。Ti, V, Cr, Mn, Fe, Co, Ni
And the total content of 3d transition metal elements of Cu is 100 ppb or less in weight ratio. This is because, similarly to the above-mentioned alkali metal element and alkaline earth metal element, it is better to handle the total amount than to limit the individual amounts, and to deal with the absorption of ultraviolet rays. If reduced to less than 100 ppb, the absorption attributed to these impurities will be almost completely eliminated.
【００２４】石英ガラス中のＯＨ基の濃度は、重量比に
て50ppm以下とする。これは50ppmを超える量が存在する
と、目標とする波長165〜200nmの範囲の、とくに短波長
側での透過率が低下してくるからである。The concentration of OH groups in the quartz glass is set to 50 ppm or less by weight. This is because if the amount exceeds 50 ppm, the transmittance in the target wavelength range of 165 to 200 nm, particularly on the short wavelength side, decreases.
【００２５】Ｂ、ＣまたはＮの含有量は、いずれも1ppm
以下とする。これは、これらいずれの元素もその含有量
が1ppmを超えると、波長165〜200nmの範囲での吸収が増
し、透過率が低下するからである。The content of B, C or N is 1 ppm
The following is assumed. This is because when the content of any of these elements exceeds 1 ppm, absorption in the wavelength range of 165 to 200 nm increases, and the transmittance decreases.
【００２６】ハロゲン元素は、上述の各不純物元素の石
英ガラス中含有量が本発明の定める範囲であれば、とく
に含有させる必要はない。合成石英ガラスは四塩化珪素
などの化合物を加水分解して製造するので、ハロゲン元
素のＣｌなどが残存することがあるが、減圧や真空中で
の処理が製造工程にて施されると、このようなハロゲン
元素は通常10ppm以下にまで低下している。The halogen element need not be particularly contained as long as the content of each of the above-mentioned impurity elements in the quartz glass is within the range defined by the present invention. Since synthetic quartz glass is produced by hydrolyzing a compound such as silicon tetrachloride, halogen such as Cl may remain. Such halogen elements are usually reduced to 10 ppm or less.
【００２７】しかし、上述の各不純物元素を低減させる
目的でハロゲン処理をおこなうと、その結果として含有
されることになる。ハロゲン処理をおこなって不純物を
十分低下させた場合、100ppm以上のハロゲン元素が含有
される。逆にハロゲン元素の含有が100ppm未満の処理で
は、その処理による不純物元素の低減がおこなわれてい
ないとも言うことができる。しかしハロゲン処理が過剰
に施され、含有量が3000ppmを超えるようになると、石
英ガラスを軟化点以上に加熱したとき気泡を形成するこ
とがあり、次に述べる水素含有の効果が十分作用しなく
なる。したがって、ハロゲン元素の含有量は100〜3000p
pmとする。ハロゲン元素としてはＦ、Ｃｌ、Ｂｒおよび
Ｉのいずれかの一種以上でよいが、実用的にはＦまたは
Ｃｌを用いるのがよい。However, if a halogen treatment is performed for the purpose of reducing each of the above-mentioned impurity elements, they will be contained as a result. When impurities are sufficiently reduced by performing a halogen treatment, a halogen element of 100 ppm or more is contained. Conversely, it can be said that in the treatment in which the content of the halogen element is less than 100 ppm, the impurity element is not reduced by the treatment. However, if the halogen treatment is excessively performed and the content exceeds 3000 ppm, bubbles may be formed when the quartz glass is heated to a temperature higher than the softening point, and the effect of hydrogen content described below does not work sufficiently. Therefore, the content of halogen element is 100-3000p
pm. As the halogen element, any one or more of F, Cl, Br and I may be used, but practically, F or Cl is preferably used.
【００２８】ハロゲン元素が含有された場合、短波長の
紫外線透過率が大きく低下するので、これを防止するた
め水素を含有させる。この水素の含有量は1×1017分子/
cm3以上必要とする。1×1017分子/cm3未満では効果が不
十分だからである。水素の含有量は多くてもかまわない
が、多く含有させるには高圧の水素雰囲気中で高温加熱
する必要があり、通常の実施は困難なので、多くても1
×1019分子/cm3程度までとするのがよい。When the halogen element is contained, the transmittance of short-wavelength ultraviolet rays is greatly reduced. To prevent this, hydrogen is contained. The content of this hydrogen is 1 × 10 17 molecules /
cm 3 and more than necessary. This is because an effect of less than 1 × 10 17 molecules / cm 3 is insufficient. Although the content of hydrogen may be large, it is necessary to perform high-temperature heating in a high-pressure hydrogen atmosphere to make a large amount of hydrogen contained.
× 10 19 molecules / cm 3 is preferable.
【００２９】上記の合成石英ガラスはＶＡＤ法に準じた
工程にて製造する。ＶＡＤ法は、火炎中で珪素化合物の
加水分解反応により生じたＳｉＯ2の微粒子を、出発材
に堆積させて石英の多孔体（スート体）とし、これを加
熱焼結して透明な石英母材を得るものである。本発明の
石英ガラスにてとくにその含有量を限定するアルカリ金
属元素、アルカリ土類金属元素および３ｄ遷移元素は、
いずれも原料の珪素化合物に由来することが多いので、
珪素化合物の段階にて前述のレベルに達している、十分
に精製された原料を用いることが望ましい。The above synthetic quartz glass is manufactured by a process according to the VAD method. In the VAD method, fine particles of SiO 2 generated by a hydrolysis reaction of a silicon compound in a flame are deposited on a starting material to form a porous quartz body (soot body), which is heated and sintered to form a transparent quartz base material. Is what you get. In the quartz glass of the present invention, particularly, the alkali metal element, the alkaline earth metal element and the 3d transition element which limit the content thereof are:
Since both are often derived from the silicon compound of the raw material,
It is desirable to use a sufficiently purified raw material that has reached the above-mentioned level at the silicon compound stage.
【００３０】加水分解反応における火炎中の反応の温度
および燃料（水素など）と酸素の比を制御することによ
り、ＯＨ基の濃度を変えることができる。形成直後のス
ート体におけるＯＨ基の濃度は、500〜1500ppm程度とや
や多めにすることが好ましい。これは、透明化後の石英
ガラス中のＯＨ基は50ppm以下とするが、このＯＨ基が
離脱する過程で同時に不純物の低減がおこなわれ、スー
ト体のＯＨ基はある程度多く含まれている方が不純物を
より効果的に排除できるからである。500ppmを下回るＯ
Ｈ基の濃度では離脱に伴う不純物の排除効果が不十分で
あり、1500ppmを超える濃度では、透明化した製品中の
ＯＨ基の濃度を50ppm以下に低減できなくなるおそれが
ある。The concentration of OH groups can be changed by controlling the temperature of the reaction in the flame in the hydrolysis reaction and the ratio of fuel (such as hydrogen) to oxygen. It is preferable that the concentration of the OH group in the soot body immediately after formation is slightly higher, about 500 to 1500 ppm. This is because the OH groups in the quartz glass after being transparentized are set to 50 ppm or less, but impurities are simultaneously reduced in the process of releasing the OH groups, and the OH groups of the soot body are contained to some extent. This is because impurities can be more effectively eliminated. O below 500ppm
If the concentration of the H group is insufficient, the effect of removing impurities accompanying the desorption is insufficient. If the concentration exceeds 1500 ppm, the concentration of the OH group in the transparent product may not be reduced to 50 ppm or less.
【００３１】各種不純物およびＯＨ基を低減した本発明
の合成ガラスとするには、精製した原料の使用に加え
て、スート体に減圧処理またはハロゲン処理をおこなっ
てから透明化する。In order to obtain the synthetic glass of the present invention in which various impurities and OH groups are reduced, the soot body is subjected to a reduced pressure treatment or a halogen treatment, and then is made transparent in addition to the use of the purified raw material.
【００３２】減圧処理をおこなう場合、スート体は500P
a以下の減圧不活性雰囲気下にて、1000〜1400℃で5〜50
時間加熱し焼結を進行させる。不活性雰囲気としては、
Ｎ含有量を低減させるため、窒素は使用せずヘリウム、
アルゴンなどを用いる。この処理によって、Ｎの含有量
は1ppm以下に低減することができる。When performing a decompression treatment, the soot body is 500P
a 5 to 50 at 1000 to 1400 ° C under a reduced pressure inert atmosphere below
Heat for a time to advance sintering. As an inert atmosphere,
In order to reduce the N content, helium without using nitrogen,
Argon or the like is used. By this treatment, the N content can be reduced to 1 ppm or less.
【００３３】500Pa以下の減圧とするのは、この処理過
程で、ＯＨ基の濃度が低下するとともにＢおよびＣの含
有量を低減させることができるからである。不活性気体
を用いるのは、脱ＯＨ基効果を高めるためである。こと
にヘリウムの利用は効果的であるが、これは多孔質のガ
ラス中の拡散速度が速いためと思われる。しかし500Pa
を超える圧力では脱ＯＨ効果ばかりでなくＢ、Ｃ、ある
いはＮの低減効果も減退してくる。なお、減圧の圧力の
下限は特には限定しないが、20Paを下回る真空であって
もよく、同様な効果を得ることができる。The reason why the pressure is reduced to 500 Pa or less is that the concentration of OH groups can be reduced and the contents of B and C can be reduced in this process. The inert gas is used to enhance the deOH group effect. The use of helium is particularly effective, presumably because of the high diffusion rate in porous glass. But 500Pa
If the pressure exceeds, not only the deOH effect but also the effect of reducing B, C or N decreases. The lower limit of the reduced pressure is not particularly limited, but may be a vacuum lower than 20 Pa, and the same effect can be obtained.
【００３４】処理温度を1000〜1400℃とするのは、1000
℃未満ではこのような反応の進行が遅くなるからであ
り、1400℃を超えると、焼結が進んで緻密で透明な石英
となり、気体との接触面積が大きい多孔質状態が失われ
るためである。The processing temperature of 1000 to 1400 ° C.
If the temperature is lower than 1 ° C., the progress of such a reaction is slow.If the temperature is higher than 1400 ° C., sintering proceeds to form a dense and transparent quartz, and a porous state having a large contact area with a gas is lost. .
【００３５】このスート体の1000〜1400℃での減圧処理
は、時間が短すぎると上記不純物低減やＯＨ基濃度低下
の効果が不十分であり、また長すぎてもそれ以上の効果
は得られなくなるので、5〜50時間とするのが望まし
い。When the soot body is subjected to a reduced pressure treatment at 1000 to 1400 ° C., if the time is too short, the effects of reducing the impurities and the OH group concentration are insufficient, and if the time is too long, further effects can be obtained. It is preferable to set the time to 5 to 50 hours, since it will disappear.
【００３６】減圧処理の後、20Pa以下の真空中または不
活性ガス雰囲気にて1300〜1600℃で透明化処理をおこな
う。この場合、ＯＨ基濃度の低下やさらなる不純物の減
少などの点から、不活性ガス雰囲気よりも真空中が好ま
しい。1300℃未満の加熱温度では透明化に長時間を要
し、1600℃を超える温度での加熱は軟化による変形を生
じさせる。After the reduced pressure treatment, a clearing treatment is performed at 1300 to 1600 ° C. in a vacuum of 20 Pa or less or in an inert gas atmosphere. In this case, it is preferable to use a vacuum rather than an inert gas atmosphere from the viewpoint of a decrease in OH group concentration and a further decrease in impurities. At a heating temperature of less than 1300 ° C., it takes a long time for transparency, and heating at a temperature of more than 1600 ° C. causes deformation due to softening.
【００３７】ハロゲン処理をおこなう場合、スート体は
ハロゲン元素を含む雰囲気中にて、700〜1200℃で2〜20
時間加熱する。ハロゲン元素を含む雰囲気としては、ハ
ロゲン元素Ｆ、Ｃｌ、ＢｒまたはＩをＸで表せば、Ｘ2
の分子、ＳｉＸ4の四珪化物、ＳｉＨＸ3のシラン化合物
など気体のハロゲン化物を、ヘリウムやアルゴンなどに
容積比で2〜20％程度混合させたものを用いればよい。When performing the halogen treatment, the soot body is heated at 700 to 1200 ° C. in an atmosphere containing a halogen element for 2 to 20 hours.
Heat for hours. As an atmosphere containing a halogen element, if the halogen element F, Cl, Br or I is represented by X, X 2
A mixture of gaseous halides, such as a molecule of the above, a tetrasilicide of SiX 4 , and a silane compound of SiHX 3 , mixed with helium or argon at a volume ratio of about 2 to 20% may be used.
【００３８】700〜1200℃とするのは、700℃未満ではハ
ロゲン化による不純物低減が不十分であり、1200℃を超
える温度ではハロゲン元素が過剰に含まれてしまうから
である。処理時間はスート体の大きさにより適宜選定す
ればよいが、1時間未満では処理効果が不十分になるお
それがあり、20時間を超える処理は過剰なハロゲン元素
含まれてしまう傾向がある。The reason why the temperature is set to 700 to 1200 ° C. is that if the temperature is lower than 700 ° C., the reduction of impurities by halogenation is insufficient, and if the temperature exceeds 1200 ° C., the halogen element is excessively contained. The treatment time may be appropriately selected depending on the size of the soot body. However, if the treatment time is less than 1 hour, the treatment effect may be insufficient, and the treatment exceeding 20 hours tends to include an excessive halogen element.
【００３９】ハロゲン処理の後、不活性ガス雰囲気また
は20Pa以下の真空中にて1300〜1600℃で透明化処理をお
こなう。1300℃未満の加熱温度では透明化に長時間を要
し、1600℃を超える温度での加熱は、軟化による変形や
気泡を生じさせるおそれがある。After the halogen treatment, a clearing treatment is performed at 1300 to 1600 ° C. in an inert gas atmosphere or a vacuum of 20 Pa or less. If the heating temperature is lower than 1300 ° C., it takes a long time to achieve transparency, and if the heating temperature is higher than 1600 ° C., deformation or bubbles may be caused by softening.
【００４０】[0040]
【実施例】〔実施例１〕表１に示す不純物を含む石英ガ
ラスを作製した。基準の製造方法は、高純度の四塩化珪
素（ＳｉＣｌ4）を原料に用い、酸素−水素炎にて加水
分解反応により石英ガラス微粒子を合成するとともに、
これを種棒の周囲に付着堆積させて多孔質合成石英ガラ
ス体（スート体）を形成し、次いで20Pa以下の真空中15
00℃にて透明化し、直径約165mm、高さ約250mmの石英母
材（プリフォーム材）を得る。EXAMPLES Example 1 Quartz glass containing impurities shown in Table 1 was produced. The standard production method uses high-purity silicon tetrachloride (SiCl 4 ) as a raw material, synthesizes quartz glass fine particles by a hydrolysis reaction in an oxygen-hydrogen flame,
This is adhered and deposited around a seed rod to form a porous synthetic quartz glass body (soot body).
It becomes transparent at 00 ° C. to obtain a quartz base material (preform material) having a diameter of about 165 mm and a height of about 250 mm.
【００４１】この場合、比較用のプリフォーム材の製造
は、次のようにした。ＯＨ基の濃度はスート体の段階に
て100ppm前後となるように、ガスの流量比を制御して水
素／酸素の比を1.0〜1.2とした。これが真空下の透明化
熱処理によって、20〜50ppm程度のＯＨ基濃度となる。
ＯＨの濃度を高めた石英は、合成時の水素／酸素の比を
大きくし、透明化時の不活性雰囲気の分圧を500Pa程度
まであげることにより製造した。アルカリ金属およびア
ルカリ土類金属の含有量は、原料ガスの純度管理により
変えた。Ｎ量の多い石英は、100Paの減圧窒素雰囲気と
して透明化の熱処理をおこなった。Ｃの多い石英は、酸
水素炎ではなく、酸素−プロパン炎を用いた。また原料
ガスに微量の水素化Ｂを添加することにより、Ｂの含有
量を変えた。In this case, a preform material for comparison was manufactured as follows. The flow rate ratio of the gas was controlled so that the hydrogen / oxygen ratio was 1.0 to 1.2 so that the concentration of the OH group was about 100 ppm at the stage of the soot body. This results in an OH group concentration of about 20 to 50 ppm by the transparent heat treatment under vacuum.
Quartz with an increased OH concentration was produced by increasing the ratio of hydrogen / oxygen during synthesis and increasing the partial pressure of the inert atmosphere during transparency to about 500 Pa. The contents of the alkali metals and alkaline earth metals were changed by controlling the purity of the raw material gas. Quartz containing a large amount of N was subjected to a heat treatment for transparency in a reduced-pressure nitrogen atmosphere of 100 Pa. For the C-rich quartz, an oxygen-propane flame was used instead of an oxyhydrogen flame. The content of B was changed by adding a small amount of hydrogenated B to the raw material gas.
【００４２】これに対し、本発明の石英ガラスについて
は、高純度の四塩化珪素を原料に用い、水素／酸素のガ
ス流量比を1.3〜1.5として、ＯＨ濃度が約800ppmのスー
ト体とした後、100Paの減圧ヘリウム雰囲気中にて1200
℃、10時間の熱処理をおこなった。次いでこれを20Pa以
下の真空中で1500℃にて透明化しプリフォーム材とし
た。On the other hand, in the case of the quartz glass of the present invention, high-purity silicon tetrachloride was used as a raw material, the gas flow ratio of hydrogen / oxygen was 1.3 to 1.5, and the soot body having an OH concentration of about 800 ppm was obtained. , 1200 Pa in a reduced pressure helium atmosphere of 100 Pa
Heat treatment was performed at 10 ° C. for 10 hours. Next, this was transparentized at 1500 ° C. in a vacuum of 20 Pa or less to obtain a preform material.
【００４３】これらプリフォーム材は、1600℃に加熱し
約200kg/cm2の圧力にて加圧成形し、直径約260mm、高さ
約100mmの石英インゴットとした。このインゴットから
試験片を切り出し、不純物の含有量を分析した結果を表
１に示す。その場合、アルカリ金属元素、アルカリ土類
金属元素および３ｄ遷移金属元素の定量は原子吸光光度
法によった。Ｂ、ＣまたはＮについてはそれぞれフレー
ムレス原子吸光法、放射化分析法または脱ガス（ＴＤ
Ｓ）分析法を用いた。ＯＨ基濃度は赤外線吸収法にて測
定した。なお、これらのガラスのハロゲン元素の含有量
を分析した結果は、合計でも10ppm未満であった。These preform materials were heated to 1600 ° C. and pressed under a pressure of about 200 kg / cm 2 to form a quartz ingot having a diameter of about 260 mm and a height of about 100 mm. A test piece was cut out from this ingot and the result of analyzing the content of impurities is shown in Table 1. In that case, the quantification of the alkali metal element, alkaline earth metal element and 3d transition metal element was based on atomic absorption spectrometry. For B, C or N, flameless atomic absorption spectrometry, activation analysis or degassing (TD
S) An analytical method was used. The OH group concentration was measured by an infrared absorption method. In addition, the result of analyzing the content of the halogen element in these glasses was less than 10 ppm in total.
【００４４】[0044]
【表１】 [Table 1]
【００４５】各石英インゴットから一辺10mmの正立方体
形状の試料を切り出し、紫外線の透過度を測定する対向
面をそれぞれ研磨して、表面反射損失をできるだけ少な
くするため、最終的には酸化セリウム粉末を用い、Ｒａ
≦5nmの鏡面仕上げとした。透過率の測定には、真空紫
外分光計（日本分光社製VUV-200）を用い、140〜300nm
の範囲の紫外線の吸収を計測した。165nm、180nmおよび
200nmの波長における1cmあたりの吸収率の測定結果も併
せて表１に示す。A cubic sample of 10 mm on a side was cut out from each quartz ingot, and the opposing surfaces for measuring the transmittance of ultraviolet rays were polished to reduce surface reflection loss as much as possible. Used, Ra
Mirror finish of ≦ 5 nm. The transmittance was measured using a vacuum ultraviolet spectrometer (VUV-200 manufactured by JASCO Corporation) at 140 to 300 nm.
The UV absorption in the range was measured. 165nm, 180nm and
Table 1 also shows the measurement results of the absorptance per cm at a wavelength of 200 nm.
【００４６】これらの結果から明らかなように、本発明
の試番1〜4の石英ガラスは、通常の方法ないしは不純物
の多い試番5〜16の石英ガラスに比較し、165〜200nmの
紫外線の1cmあたりの透過率が85％以上とすぐれてい
る。これはＯＨ基濃度が低く、アルカリ金属元素、アル
カリ土類金属元素およ３ｄ遷移金属元素の含有量が低レ
ベルにあり、かつＢ、Ｃ、Ｎの含有量が特に低いことに
よっている。As is evident from these results, the quartz glass of Nos. 1 to 4 of the present invention was compared with the quartz glass of Nos. 5 to 16 containing a large amount of impurities by the conventional method or the quartz glass of Nos. 5 to 16 having a large amount of impurities. The transmittance per cm is excellent at 85% or more. This is because the OH group concentration is low, the contents of alkali metal elements, alkaline earth metal elements and 3d transition metal elements are at low levels, and the contents of B, C and N are particularly low.
【００４７】〔実施例２〕高純度の四塩化珪素を原料に
用い、水素／酸素のガス流量比を1.3〜1.5としてＯＨ基
濃度が約800ppmのスート体を作成した。ハロゲン処理
は、このスート体を加熱し、その間に塩素ガス（Ｃ
ｌ2）または四弗化珪素（ＳｉＦ4）をヘリウムに混合し
たガスを、炉内に流入しつつおこなった。加熱時間はい
ずれも６時間としたが、混合ガスの濃度および温度は表
２に示すように変えた。次いでこれをヘリウム雰囲気で
1500℃にて透明化しプリフォーム材とした。Example 2 A soot having an OH group concentration of about 800 ppm was prepared using high-purity silicon tetrachloride as a raw material and a hydrogen / oxygen gas flow ratio of 1.3 to 1.5. The halogen treatment heats the soot body, during which chlorine gas (C
l 2 ) or a gas obtained by mixing silicon tetrafluoride (SiF 4 ) with helium was introduced into the furnace. The heating time was 6 hours in each case, but the concentration and temperature of the mixed gas were changed as shown in Table 2. Then, in a helium atmosphere
It was made transparent at 1500 ° C to obtain a preform material.
【００４８】これらプリフォーム材は、1600℃に加熱し
約200kg/cm2の圧力にて加圧成形し、直径約260mm、高さ
約100mmの石英インゴットとした。インゴットは100％の
水素中にて800℃で50時間保持の水素処理をおこなっ
た。各石英インゴットは実施例１と同様、一辺10mmの正
立方体形状の試料を切り出し、紫外線吸収を測定した。
また、水素含有量はラマン分光法により測定し、Ｃｌま
たはＦの含有量はそれぞれ塩化銀沈殿法またはイオンク
ロマトグラフ法により測定した。その他、不純物金属元
素、Ｂ、ＣまたはＮ、およびＯＨ基濃度等は、実施例１
と同様な方法で分析した。結果をまとめて表２に示す。These preform materials were heated to 1600 ° C. and pressed under a pressure of about 200 kg / cm 2 to obtain a quartz ingot having a diameter of about 260 mm and a height of about 100 mm. The ingot was subjected to hydrogen treatment in 100% hydrogen at 800 ° C. for 50 hours. As in Example 1, each quartz ingot was cut out of a cube-shaped sample having a side of 10 mm, and the ultraviolet absorption was measured.
The hydrogen content was measured by Raman spectroscopy, and the Cl or F content was measured by silver chloride precipitation or ion chromatography, respectively. In addition, the impurity metal element, B, C or N, and the OH group concentration were determined in Example 1.
The analysis was performed in the same manner as described above. Table 2 summarizes the results.
【００４９】[0049]
【表２】 [Table 2]
【００５０】これから明らかなように、実施例１とほぼ
同じ高純度の四塩化珪素を原料に用いているにもかかわ
らず、ＯＨ基ばかりでなく各不純物元素は大幅に低下し
ていることがわかる。しかし、試番21または25の水素処
理をおこなわず水素含有量の低い場合、あるいは試番20
の水素処理をおこなってもハロゲン元素が本発明の定め
る範囲を超える場合は、165nmの短波長における透過率
が極めて悪い結果を示している。これに対し、本発明の
試番17〜19または試番22〜24の石英ガラスはいずれも16
5nm以上の波長での透過率がすぐれていることがわか
る。As is clear from this, not only the OH group but also each of the impurity elements are greatly reduced, although the same high purity silicon tetrachloride as in Example 1 is used as the raw material. . However, if the hydrogen content is low without performing the hydrogen treatment of Test No. 21 or 25, or
When the halogen element exceeds the range defined by the present invention even after the hydrogen treatment, the transmittance at a short wavelength of 165 nm is extremely poor. On the other hand, the quartz glass of Test Nos. 17 to 19 or 22 to 24 of the present invention was 16
It can be seen that the transmittance at a wavelength of 5 nm or more is excellent.
【００５１】[0051]
【発明の効果】本発明の合成石英ガラスは、とくに波長
が165〜200nmの範囲の遠紫外領域にて光の吸収が少な
く、ＬＳＩの高集積度化における短波長光の利用に対
し、光リソグラフィーの光学系や、マスクの基材などに
効果的に活用できる。The synthetic quartz glass of the present invention has low light absorption especially in the deep ultraviolet region having a wavelength in the range of 165 to 200 nm. It can be effectively used for optical systems and mask base materials.
───────────────────────────────────────────────────── 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） Ｇ０３Ｆ 7/20 ５２１ Ｇ０３Ｆ 7/20 ５２１ Ｈ０１Ｌ 21/027 Ｈ０１Ｌ 21/30 ５１５Ｄ ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) G03F 7/20 521 G03F 7/20 521 H01L 21/027 H01L 21/30 515D
Claims (4)
ａ、Ｋ、およびアルカリ土類金属元素Ｍｇ、Ｃａの合計
の含有量が100ppb以下、３ｄ遷移金属元素Ｔｉ、Ｖ、Ｃ
ｒ、Ｍｎ、Ｆｅ、Ｃｏ、ＮｉおよびＣｕの合計の含有量
が100ppb以下、Ｂ、ＣまたはＮの含有量のいずれもが1p
pm以下で、さらにＯＨ基の濃度が50ppm以下であること
を特徴とする波長165〜200nmの光の透過率が光路長1cm
あたり85％以上の合成石英ガラス。1. An alkali metal element Li, N
a, K, and the total content of alkaline earth metal elements Mg and Ca is 100 ppb or less, 3d transition metal elements Ti, V, C
The total content of r, Mn, Fe, Co, Ni and Cu is 100 ppb or less, and the content of B, C or N is 1 p.
pm or less, and the transmittance of light having a wavelength of 165 to 200 nm, wherein the OH group concentration is 50 ppm or less, has an optical path length of 1 cm.
85% or more synthetic quartz glass.
ａ、Ｋ、およびアルカリ土類金属元素Ｍｇ、Ｃａの合計
の含有量が100ppb以下、３ｄ遷移金属元素Ｔｉ、Ｖ、Ｃ
ｒ、Ｍｎ、Ｆｅ、Ｃｏ、ＮｉおよびＣｕの合計の含有量
が100ppb以下、Ｂ、ＣまたはＮの含有量のいずれもが1p
pm以下、ＯＨ基の濃度が50ppm以下で、ハロゲン元素
Ｆ、Ｃｌ、ＢｒおよびＩの合計の含有量が100〜3000pp
m、水素分子の含有量が1×1017分子/cm3以上であること
を特徴とする波長165〜200nmの光の透過率が光路長1cm
あたり85％以上の合成石英ガラス。2. An alkali metal element Li, N
a, K, and the total content of alkaline earth metal elements Mg and Ca is 100 ppb or less, 3d transition metal elements Ti, V, C
The total content of r, Mn, Fe, Co, Ni and Cu is 100 ppb or less, and the content of B, C or N is 1 p.
pm or less, OH group concentration is 50 ppm or less, and the total content of halogen elements F, Cl, Br and I is 100 to 3000 pp.
m, the content of hydrogen molecules is 1 × 10 17 molecules / cm 3 or more, the transmittance of light having a wavelength of 165 to 200 nm is 1 cm in optical path length.
85% or more synthetic quartz glass.
ＯＨ基濃度が500〜1500ppmの多孔質合成石英ガラス体
（スート体）とし、これを500Pa以下の減圧不活性雰囲
気下で1000〜1400℃にて5〜50時間加熱保持し、次いで2
0Pa以下の真空中または不活性雰囲気中にて1300〜1600
℃で透明化させることを特徴とする請求項１に記載の合
成石英ガラスの製造方法。3. A porous synthetic quartz glass body (soot body) having an OH group concentration of 500 to 1500 ppm by a hydrolysis reaction of a silicon compound in a flame, which is carried out at 1000 to 1400 ° C. under a reduced pressure inert atmosphere of 500 Pa or less. For 5 to 50 hours.
1300 to 1600 in a vacuum of 0 Pa or less or in an inert atmosphere
The method for producing a synthetic quartz glass according to claim 1, wherein the method is made transparent at a temperature of ° C.
ＯＨ基濃度が500〜1500ppmの多孔質合成石英ガラス体
（スート体）とし、これをハロゲン元素またはハロゲン
化物を含む雰囲気中で700〜1200℃にて2〜20時間加熱保
持するハロゲン処理を施し、次いで20Pa以下の真空中ま
たは不活性雰囲気中にて1300〜1600℃で透明化させるこ
とを特徴とする請求項２に記載の合成石英ガラスの製造
方法。4. A porous synthetic quartz glass body (soot body) having an OH group concentration of 500 to 1500 ppm by a hydrolysis reaction of a silicon compound in a flame, which is 700 to 1200 ppm in an atmosphere containing a halogen element or a halide. The synthetic quartz glass according to claim 2, wherein a halogen treatment is performed by heating and holding at 2C for 2 to 20 hours, and then the mixture is made transparent at 1300 to 1600C in a vacuum or an inert atmosphere of 20Pa or less. Manufacturing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000158606A JP2001048571A (en) | 1999-06-04 | 2000-05-29 | Quartz glass excellent in transmission of short wavelength light, and its production |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15739399 | 1999-06-04 | ||
| JP11-157393 | 1999-06-04 | ||
| JP2000158606A JP2001048571A (en) | 1999-06-04 | 2000-05-29 | Quartz glass excellent in transmission of short wavelength light, and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001048571A true JP2001048571A (en) | 2001-02-20 |
Family
ID=26484864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000158606A Pending JP2001048571A (en) | 1999-06-04 | 2000-05-29 | Quartz glass excellent in transmission of short wavelength light, and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001048571A (en) |
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| US11053152B2 (en) | 2015-12-18 | 2021-07-06 | Heraeus Quarzglas Gmbh & Co. Kg | Spray granulation of silicon dioxide in the preparation of quartz glass |
| US11236002B2 (en) | 2015-12-18 | 2022-02-01 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of an opaque quartz glass body |
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| US10618833B2 (en) | 2015-12-18 | 2020-04-14 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of a synthetic quartz glass grain |
| US11492282B2 (en) | 2015-12-18 | 2022-11-08 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of quartz glass bodies with dew point monitoring in the melting oven |
| US11492285B2 (en) | 2015-12-18 | 2022-11-08 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of quartz glass bodies from silicon dioxide granulate |
| US11708290B2 (en) | 2015-12-18 | 2023-07-25 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of a quartz glass body in a multi-chamber oven |
| CN112384483B (en) * | 2018-07-06 | 2023-06-20 | 卡尔蔡司Smt有限责任公司 | Substrate of reflective optical element |
| CN112384483A (en) * | 2018-07-06 | 2021-02-19 | 卡尔蔡司Smt有限责任公司 | Substrate for reflective optical element |
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