JP2002121038A - Heat treatment method for synthetic quartz glass - Google Patents
Heat treatment method for synthetic quartz glassInfo
- Publication number
- JP2002121038A JP2002121038A JP2000309507A JP2000309507A JP2002121038A JP 2002121038 A JP2002121038 A JP 2002121038A JP 2000309507 A JP2000309507 A JP 2000309507A JP 2000309507 A JP2000309507 A JP 2000309507A JP 2002121038 A JP2002121038 A JP 2002121038A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- heat treatment
- quartz glass
- synthetic quartz
- virtual temperature
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は紫外線波長を有する
レーザを用いる光学系装置に使用するのに好適な合成石
英ガラスを製造するための熱処理方法に係り、特に、光
学系装置のレンズ、ミラー、プリズムなど直接紫外線波
長を有するレーザを入射する光学部材として使用される
合成石英ガラスを製造するための熱処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for producing synthetic quartz glass suitable for use in an optical system using a laser having an ultraviolet wavelength, and more particularly, to a lens, a mirror, and a mirror for an optical system. The present invention relates to a heat treatment method for producing synthetic quartz glass used as an optical member that directly receives a laser having an ultraviolet wavelength, such as a prism.
【0002】[0002]
【従来の技術】現在、情報技術産業は、急速な成長を続
けている。情報技術産業の成長には、扱える情報量の拡
大が不可欠であり、情報処理装置には高速化、高集積化
が求められている。MPUなどの高速化、高集積化に対し
ては、多方面からの研究開発が行われており、特に製造
面からは、例えば、変形照明法、位相シフトマスク法な
ど光の干渉を利用した超解像度リソグラフィー技術が開
発されている。一方で、リソグラフィ技術の解像度を上
げる最も簡便な技術として、リソグラフィ技術で用いる
光源の短波長化が挙げられる。2. Description of the Related Art At present, the information technology industry is growing rapidly. For the growth of the information technology industry, an increase in the amount of information that can be handled is indispensable, and information processing apparatuses are required to have higher speed and higher integration. Research and development are being carried out from various directions for high speed and high integration of MPUs, etc., especially from the manufacturing side, for example, ultra-light interference such as deformation illumination method and phase shift mask method. Resolution lithography technology has been developed. On the other hand, the simplest technique for increasing the resolution of the lithography technique is to shorten the wavelength of a light source used in the lithography technique.
【0003】リソグラフィ技術を用いるに当たり、従
来、その光源として、水銀ランプ(g線(436nm)、i線(36
5nm))が用いられてきた。比較的波長の長いg線、i線
は、光源のもつエネルギーが小さいため、光学部材自体
が光照射によってダメージを負うことはほとんどない。
しかし、現在では、光源の短波長化に伴い、KrFやArFを
発振源とするエキシマレーザが用いられるようになり、
従来用いられてきた光学部材では容易にダメージを負っ
てしまうことから、新たな光学部材として石英ガラスの
使用が不可欠となった。In using the lithography technology, mercury lamps (g-line (436 nm), i-line (36
5 nm)). Since g-rays and i-rays having relatively long wavelengths have low energy of the light source, the optical member itself is hardly damaged by light irradiation.
However, with the shortening of the wavelength of the light source, excimer lasers using KrF or ArF as an oscillation source are now being used.
Conventionally used optical members are easily damaged, and thus the use of quartz glass as a new optical member has become indispensable.
【0004】光学部材用の石英ガラスには、特に光透過
性やレーザ耐性などの特性が要求される。エキシマレー
ザは、基本的に石英ガラスに対し光透過性を有するが、
石英ガラス中に不純物が混入していると、光透過性は低
下する。初期光透過性を向上させるためには、金属、OH
基、ハロゲン等の不純物を除去し、高純度の石英ガラス
を製造する必要がある。よって、いわゆるVAD法と呼ば
れる製造方法により、高純度の珪素化合物を酸素水素火
炎中で加水分解して得た合成石英ガラスが好んで用いら
れている。[0004] Quartz glass for optical members is required to have characteristics such as light transmittance and laser resistance. Excimer laser basically has optical transparency to quartz glass,
When impurities are mixed in the quartz glass, the light transmittance decreases. To improve the initial light transmittance, metal, OH
It is necessary to manufacture high-purity quartz glass by removing impurities such as bases and halogens. Therefore, a synthetic quartz glass obtained by hydrolyzing a high-purity silicon compound in an oxygen-hydrogen flame by a so-called VAD method is preferably used.
【0005】一方で、不純物を除去しただけでは、エキ
シマレーザの照射による光透過性の低下は防止できな
い、すなわち、レーザに対する耐久力(レーザ耐性)は
向上しない。合成石英ガラスは、レーザ照射されると、
その大きなエネルギー密度により、石英ガラスの網目構
造が損傷を受け、いわゆるE’センター(≡Si・;≡は
3つの酸素と結合していることを示し、・は不対電子を
示す。)に起因する波長215nm付近の吸収帯やNon-Bridg
ing Oxygen Hole Center(NBOHC、≡Si-O・)に起因す
る波長260nm付近の吸収帯等、多種多様の吸収帯が形成
され、光透過性が低下する。これらの欠陥の形成を防止
するには、石英ガラス中の構造を安定なものにしておく
必要がある。[0005] On the other hand, the mere removal of impurities cannot prevent a decrease in light transmittance due to the irradiation of the excimer laser, that is, does not improve the durability against laser (laser resistance). When the synthetic quartz glass is irradiated with a laser,
Due to its large energy density, the network structure of quartz glass is damaged, and is caused by the so-called E ′ center ({Si .;} indicates that it is bonded to three oxygen atoms, and • indicates an unpaired electron). Absorption band around Non-Bridg
A wide variety of absorption bands, such as an absorption band near a wavelength of 260 nm, caused by the ing Oxygen Hole Center (NBOHC, ≡Si-O.) are formed, and light transmittance is reduced. To prevent the formation of these defects, it is necessary to make the structure in the quartz glass stable.
【0006】例えば、合成石英ガラスは、O-Si-Oで表さ
れる6個の結合が網目状に構造をなす6員環構造と呼ば
れる安定な基本構造を有する。しかし、VAD法などによ
り、高温で短時間に合成される場合には、構造的に不安
定なものが生成しやすく、合成石英中に3員環構造、4
員環構造等の不安定構造が多数存在してしまう。これら
の不安定構造は、エキシマレーザの照射を受けると、上
記E’センターやNBOHCのような欠陥を形成し、合成石
英ガラスの光透過性を低下させる。For example, synthetic quartz glass has a stable basic structure called a six-membered ring structure in which six bonds represented by O—Si—O form a network structure. However, when synthesized at a high temperature for a short time by the VAD method or the like, structurally unstable ones are likely to be generated, and a three-membered ring structure,
Many unstable structures such as a membered ring structure exist. These unstable structures, when irradiated with excimer laser, form defects such as the E ′ center and NBOHC, and reduce the light transmittance of the synthetic quartz glass.
【0007】[0007]
【発明が解決しようとする課題】合成石英ガラス中の3
員環構造、4員環構造などの不安定構造が少ない、すな
わち、合成石英ガラスがより安定な構造を取る場合、そ
の合成石英ガラスの構造安定性の指標である仮想温度は
低下する。よって、合成石英ガラスをより安定な構造と
するには、仮想温度が低くなるような処理を施せばよ
い。特開平9-241030号公報、特開平10-67526号公報に
は、仮想温度を低下させる処理を規定して、光透過性を
改善した石英ガラスの発明が記載されている。SUMMARY OF THE INVENTION
When there are few unstable structures such as a four-membered ring structure and a four-membered ring structure, that is, when the synthetic quartz glass has a more stable structure, the fictive temperature, which is an index of the structural stability of the synthetic quartz glass, decreases. Therefore, in order to make the synthetic quartz glass have a more stable structure, it is only necessary to perform a process for lowering the virtual temperature. JP-A-9-241030 and JP-A-10-67526 disclose a quartz glass invention in which light transmittance is improved by defining a process for lowering a virtual temperature.
【0008】これらの発明の合成石英ガラスでは、仮想
温度を低くすることにより、十分な光透過性を有する
が、仮想温度を低くする熱処理には、かなりの時間がか
かる。すなわち、上記両公報に記載の発明では、仮想温
度を低くする熱処理として、仮想温度と同じ温度に保持
するため、目標とする仮想温度で平衡状態になるまで長
時間保持せざるをえず、生産性に欠けているという問題
があった。Although the synthetic quartz glass of these inventions has sufficient light transmittance by lowering the fictive temperature, a considerable time is required for heat treatment for lowering the fictive temperature. In other words, in the inventions described in the above publications, as the heat treatment for lowering the virtual temperature, the temperature is maintained at the same temperature as the virtual temperature. There was a problem of lack of sex.
【0009】本願発明の課題は、従来の仮想温度を低下
させる熱処理方法にかわる、より短時間で熱処理を終了
させ、合成石英ガラスの生産性を上げる合成石英ガラス
の熱処理方法を提供することにある。An object of the present invention is to provide a synthetic quartz glass heat treatment method which can end the heat treatment in a shorter time and improve the productivity of the synthetic quartz glass, instead of the conventional heat treatment method for lowering the virtual temperature. .
【0010】[0010]
【課題を解決するための手段】本発明者らは、合成石英
ガラスを熱処理により仮想温度を低下させる場合の仮想
温度、熱処理温度及び保持時間の関係に注目した。Means for Solving the Problems The present inventors have paid attention to the relationship among the virtual temperature, the heat treatment temperature, and the holding time when the virtual temperature is lowered by heat treatment of synthetic quartz glass.
【0011】そこで、合成石英ガラスの仮想温度(以
下、初期仮想温度という)を目標とする仮想温度(以
下、目標仮想温度という)にする際、その仮想温度が、
初期仮想温度と目標仮想温度の間にある温度(以下、中
間仮想温度という)となるように熱処理を行い、中間仮
想温度を有する合成石英ガラスを経由して、最終的に目
標仮想温度を有する合成石英ガラスを得れば、直接的に
初期仮想温度を目標仮想温度にする熱処理をするよりも
処理時間を短縮できることに気がついた。Therefore, when the virtual temperature of the synthetic quartz glass (hereinafter referred to as an initial virtual temperature) is set to a target virtual temperature (hereinafter referred to as a target virtual temperature), the virtual temperature is
Heat treatment is performed so as to be a temperature between the initial virtual temperature and the target virtual temperature (hereinafter, referred to as an intermediate virtual temperature), and finally, a synthetic material having the target virtual temperature via the synthetic quartz glass having the intermediate virtual temperature. It has been found that the processing time can be shortened by obtaining quartz glass, as compared with a heat treatment in which the initial virtual temperature is directly set to the target virtual temperature.
【0012】また、その際、仮想温度より低い温度で保
持すると、仮想温度と同じ温度で保持したときより、短
時間で目的の仮想温度に到達することを確認した。[0012] At this time, it was confirmed that when the temperature was maintained at a temperature lower than the virtual temperature, the target virtual temperature was reached in a shorter time than when the temperature was maintained at the same temperature as the virtual temperature.
【0013】本発明は、合成石英ガラスの仮想温度を低
下させる合成石英ガラスの熱処理方法であって、初期仮
想温度と目標仮想温度との間に、1以上の中間仮想温度
を設定し、合成石英ガラスを前記中間仮想温度に対応す
る中間熱処理温度に保持し、順次段階的に中間仮想温度
を低下した後、最終熱処理温度で保持し、目標仮想温度
を得ることを特徴とする合成石英ガラスの熱処理方法、
を提供する。The present invention is a method for heat treating synthetic quartz glass for lowering the virtual temperature of synthetic quartz glass, wherein one or more intermediate virtual temperatures are set between an initial virtual temperature and a target virtual temperature. Holding the glass at an intermediate heat treatment temperature corresponding to the intermediate virtual temperature, sequentially decreasing the intermediate virtual temperature, and then holding the glass at the final heat treatment temperature to obtain a target virtual temperature; Method,
I will provide a.
【0014】[0014]
【発明の実施の形態】本発明に係る熱処理方法は、合成
石英ガラスの仮想温度を低下させるために行う熱処理方
法である。仮想温度は石英ガラスの構造安定性を示す指
標となるものであり、石英ガラスの構造は、仮想温度と
して示される温度において平衡状態となる。一般に仮想
温度が低いほど石英ガラスの構造は安定であり、上述し
た3員環構造や4員環構造などの不安定構造が減少する
と言われている。よって、合成石英ガラスの仮想温度を
低くし、不安定構造を少なくすれば、レーザ照射による
透過率の低下を抑えることができ、合成ガラス自体の耐
久性を向上させることができる。BEST MODE FOR CARRYING OUT THE INVENTION The heat treatment method according to the present invention is a heat treatment method performed for lowering the fictive temperature of synthetic quartz glass. The virtual temperature is an index indicating the structural stability of the quartz glass, and the structure of the quartz glass is in an equilibrium state at a temperature indicated as the virtual temperature. Generally, it is said that the lower the fictive temperature, the more stable the structure of quartz glass, and the less the unstable structure such as the above-described three-membered ring structure or four-membered ring structure. Therefore, if the fictive temperature of the synthetic quartz glass is lowered and the unstable structure is reduced, a decrease in transmittance due to laser irradiation can be suppressed, and the durability of the synthetic glass itself can be improved.
【0015】本発明に係る熱処理方法では、初期仮想温
度と目標仮想温度の間の温度範囲内で、中間仮想温度を
設定する。前出のように、初期仮想温度とは熱処理を行
う前の仮想温度、目標仮想温度とは熱処理を行い最終的
に得ようとする仮想温度のことを言う。例えば、通常、
VAD法で製造したままの合成石英ガラスの仮想温度、す
なわち初期仮想温度は、製造条件にもよるが、1200
℃以上となることが多い。これを熱処理により順次段階
的に中間仮想温度を低下させ、最終製品に対応して設定
した目標仮想温度を有する合成石英ガラスを得る。In the heat treatment method according to the present invention, an intermediate virtual temperature is set within a temperature range between the initial virtual temperature and the target virtual temperature. As described above, the initial virtual temperature is a virtual temperature before heat treatment is performed, and the target virtual temperature is a virtual temperature to be finally obtained by heat treatment. For example, usually
The virtual temperature of the synthetic quartz glass as manufactured by the VAD method, that is, the initial virtual temperature, depends on the manufacturing conditions, but is 1200
Often above ° C. The intermediate fictive temperature is reduced step by step by heat treatment to obtain a synthetic quartz glass having a target fictive temperature set corresponding to the final product.
【0016】中間仮想温度とは、本発明の実施に当た
り、最終的に合成石英ガラスを得る前に中間的に得られ
る合成石英ガラスの仮想温度のことを言う。また、中間
熱処理温度とは、順次段階的に熱処理を行う際に保持す
る温度を言い、この温度で保持する熱処理をすることで
中間仮想温度を得る。中間仮想温度は、初期仮想温度と
目標仮想温度の間の温度範囲内で設定され、その設定数
は1あるいは複数にする。中間仮想温度は、必ずしも熱
処理全体の保持時間を最短にするように設定する必要は
ない。保持時間が最短となるように設定することが好ま
しいが、そのためのデータを蓄積するには、時間を要す
る。その設定数の上限は限定しないが、設定数が多すぎ
ると、実質的に連続徐冷することと同じになり、好まし
くない。原理的には連続徐冷してもよいが、合成石英ガ
ラスの表面部および内部の温度を均一に保ちつつ徐冷す
ることは容易ではなく、不均一になった場合には、所望
の最終仮想温度が得られないことがある。実用面を考慮
すると、設定数は、好ましくは40段階以下である。さ
らには好ましくは5段階以下である。また、初期仮想温
度と中間仮想温度、あるいは2の中間仮想温度間の温度
差は20℃以上あるのが好ましい。The term "intermediate fictive temperature" refers to a fictive temperature of synthetic quartz glass obtained intermediately before finally obtaining synthetic quartz glass in the practice of the present invention. The intermediate heat treatment temperature refers to a temperature maintained when heat treatment is performed step by step sequentially, and an intermediate virtual temperature is obtained by performing the heat treatment maintained at this temperature. The intermediate virtual temperature is set within a temperature range between the initial virtual temperature and the target virtual temperature, and the set number is one or more. The intermediate virtual temperature does not necessarily need to be set so as to minimize the holding time of the entire heat treatment. It is preferable to set the holding time to be the shortest, but it takes time to accumulate the data for that. The upper limit of the set number is not limited, but if the set number is too large, it becomes substantially the same as continuous slow cooling, which is not preferable. In principle, continuous slow cooling may be used.However, it is not easy to perform slow cooling while maintaining the surface and internal temperatures of the synthetic quartz glass uniform. Temperature may not be obtained. Considering practical aspects, the set number is preferably 40 steps or less. More preferably, the number of stages is 5 or less. Further, the temperature difference between the initial virtual temperature and the intermediate virtual temperature or between the two intermediate virtual temperatures is preferably 20 ° C. or more.
【0017】中間熱処理温度は、中間仮想温度より低く
設定することが好ましい。温度差で5〜25℃低く設定す
る。この範囲の温度を用いると、中間仮想温度と同じ温
度を用いて熱処理した場合より短時間で仮想温度を下げ
ることができる。中間熱処理温度と中間仮想温度の温度
差が5℃未満であると、保持時間が長くなる恐れがあ
り、さらに熱処理炉の温度制御の精度によっては、中間
熱処理温度が中間仮想温度よりも高くなる恐れがある。
また、温度差が25℃超である場合にも、保持時間が長く
なる恐れがある。The intermediate heat treatment temperature is preferably set lower than the intermediate virtual temperature. Set 5-25 ° C lower by the temperature difference. When the temperature in this range is used, the virtual temperature can be reduced in a shorter time than when heat treatment is performed using the same temperature as the intermediate virtual temperature. If the temperature difference between the intermediate heat treatment temperature and the intermediate virtual temperature is less than 5 ° C., the holding time may be longer, and the intermediate heat treatment temperature may be higher than the intermediate virtual temperature depending on the accuracy of the temperature control of the heat treatment furnace. There is.
Also, when the temperature difference exceeds 25 ° C., the holding time may be prolonged.
【0018】結果として、中間仮想温度を有する合成石
英ガラスを段階的に作製し、最も低い中間仮想温度のも
のを作製した後、最終熱処理温度で保持することによ
り、短時間の熱処理で、目標仮想温度の合成石英ガラス
を得ることができる。最終熱処理温度とは、目標仮想温
度を得るために行う熱処理の熱処理温度のことを言う。
この場合も、中間仮想温度と中間熱処理温度との関係と
同様に、最終熱処理温度は、目標仮想温度より5〜25℃
低く設定することが好ましい。As a result, a synthetic quartz glass having an intermediate virtual temperature is produced stepwise, a glass having the lowest intermediate virtual temperature is produced, and then maintained at the final heat treatment temperature. A synthetic quartz glass at a temperature can be obtained. The final heat treatment temperature refers to a heat treatment temperature of a heat treatment performed to obtain a target virtual temperature.
In this case, as in the relationship between the intermediate virtual temperature and the intermediate heat treatment temperature, the final heat treatment temperature is 5 to 25 ° C. higher than the target virtual temperature.
It is preferable to set it low.
【0019】本発明に係る熱処理方法を実施した場合、
任意の中間仮想温度を有する合成石英ガラスとなる段階
を経由するが、本当に設定した中間仮想温度の合成石英
ガラスが得られているかを確認するためには、各段階で
熱処理が終了した後、実際に合成石英ガラスの仮想温度
を測定する必要がある。中間仮想温度を有することを確
認した後、次の処理の段階に進むことが好ましいが、実
用的ではない。When the heat treatment method according to the present invention is performed,
After passing through the stage of forming a synthetic quartz glass having an arbitrary intermediate virtual temperature, in order to confirm that the synthetic quartz glass of the set intermediate virtual temperature is actually obtained, after the heat treatment is completed in each stage, First, it is necessary to measure the fictive temperature of the synthetic quartz glass. After confirming that it has an intermediate virtual temperature, it is preferable to proceed to the next processing stage, but this is not practical.
【0020】したがって、本発明に係る熱処理方法を実
施するに当たっては、以下のように行うのがよい。予め
蓄積したデータから、設定した中間仮想温度と対応する
熱処理温度と保持する時間を決定する。すなわち、通常
用いる製造条件で作製した合成石英ガラスの仮想温度を
初期仮想温度とし、その仮想温度より低い任意の仮想温
度(例えば、初期仮想温度より20〜50℃低い数種類の温
度)にするための熱処理温度とその熱処理に必要な保持
時間に関するデータを蓄積する。次に、そのようにして
得られた仮想温度を初期仮想温度として、同様にそれよ
り低い温度の仮想温度が得られる熱処理温度と保持時間
のデータを蓄積する。これらのデータを用い、目的の製
品に対応する目標仮想温度を勘案して、各段階の熱処理
温度と保持温度のスケジュールを決定し、熱処理を行
う。ただし、任意の仮想温度まで下げるのに必要な保持
時間が15分以下であっても、温度の均一性を維持するた
めには少なくとも15分以上保持することが好ましい。Therefore, it is preferable to carry out the heat treatment method according to the present invention as follows. From the data accumulated in advance, the heat treatment temperature corresponding to the set intermediate virtual temperature and the holding time are determined. That is, the virtual temperature of the synthetic quartz glass manufactured under the normally used manufacturing conditions is set as the initial virtual temperature, and is set to an arbitrary virtual temperature lower than the virtual temperature (for example, several kinds of temperatures 20 to 50 ° C. lower than the initial virtual temperature). Data on the heat treatment temperature and the holding time required for the heat treatment is accumulated. Next, the virtual temperature thus obtained is set as the initial virtual temperature, and data of the heat treatment temperature and the holding time at which a lower virtual temperature is obtained are also stored. Using these data, considering the target virtual temperature corresponding to the target product, the schedule of the heat treatment temperature and the holding temperature at each stage is determined, and the heat treatment is performed. However, even if the holding time required to lower the temperature to an arbitrary virtual temperature is 15 minutes or less, it is preferable to hold the temperature for at least 15 minutes or more in order to maintain the temperature uniformity.
【0021】[0021]
【実施例】本発明に係る熱処理方法を実施するに当た
り、まず熱処理を施すための合成石英ガラスをVAD法に
より作製した。はじめに、高純度四塩化ケイ素(SiC
l4)ガスをフローさせながら、酸素・水素火炎中、約175
0℃で気相化学反応(加水分解反応)させて微粒子状の
合成石英ガラスを合成した。微粒子状の合成石英ガラス
は、気相化学反応が起こる部位の上方に設置された種棒
の周囲に付着・堆積し、直径400mm×長さ1500mmの多孔
質合成石英ガラス(スート体)を形成した。DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out the heat treatment method according to the present invention, first, a synthetic quartz glass to be subjected to a heat treatment was produced by a VAD method. First, high-purity silicon tetrachloride (SiC
l 4 ) Approximately 175 in oxygen / hydrogen flame while flowing gas.
Fine particle synthetic quartz glass was synthesized by a gas phase chemical reaction (hydrolysis reaction) at 0 ° C. The fine-grained synthetic quartz glass adheres and accumulates around a seed rod placed above the site where the gas phase chemical reaction occurs, forming a porous synthetic quartz glass (soot body) measuring 400 mm in diameter and 1500 mm in length. .
【0022】続いて、このスート体を露点-70℃、圧力1
00PaのHe雰囲気中で1000℃、10時間保持して熱処理を行
う。OH処理を施した後、さらに、1550℃で6時間保持
し、透明化処理を行った。透明化処理により得られた合
成石英ガラスは、直径150mm×長さ1000mmほどのロッド
状となった。ロッド状合成石英ガラスは、ロッド断面の
中心部より中心軸に沿って、10mm×10mm×長さ40mmに切
り出して試料とした。Subsequently, the soot body was heated at a dew point of -70.degree.
The heat treatment is performed at 1000 ° C. for 10 hours in a He atmosphere of 00 Pa. After the OH treatment, the film was further kept at 1550 ° C. for 6 hours to perform a clearing treatment. The synthetic quartz glass obtained by the transparency treatment became a rod having a diameter of about 150 mm and a length of about 1000 mm. The rod-shaped synthetic quartz glass was cut into a sample of 10 mm × 10 mm × 40 mm in length along the central axis from the center of the rod section.
【0023】本発明に係る熱処理方法を実施するに先立
って、上記本試料について、諸特性を調査した。合成石
英ガラス中のOH基濃度は、赤外線吸収法により測定した
ところ、12ppm以下であった。また、金属不純物濃度の
測定には高周波誘導結合プラズマ発光分光分析法(ICP
法)を用い、その結果、各金属元素1ppb以下と不純物金
属が極めて少ないことが判明した。Prior to carrying out the heat treatment method according to the present invention, various characteristics of the sample were examined. The OH group concentration in the synthetic quartz glass was 12 ppm or less as measured by an infrared absorption method. In addition, high-frequency inductively coupled plasma emission spectroscopy (ICP
Method), and as a result, it was found that each metal element was 1 ppb or less and the amount of impurity metals was extremely small.
【0024】また、仮想温度は、レーザラマン散乱法を
用いて測定した。あらかじめ仮想温度が既知の合成石英
ガラスのデータと上記のように作製した測定データを比
較することにより、上記本試料の合成石英ガラスの仮想
温度は1220℃であることがわかった。The fictive temperature was measured by using a laser Raman scattering method. By comparing the data of the synthetic quartz glass whose fictive temperature is known in advance and the measurement data prepared as described above, it was found that the fictive temperature of the synthetic quartz glass of the present sample was 1220 ° C.
【0025】熱処理では、この仮想温度が1220℃(初期
仮想温度)の合成石英ガラスを仮想温度が1000℃(目標
仮想温度)の合成石英ガラスにする熱処理を施すことに
し、Heガス雰囲気下、表1に示す条件で、段階的に熱処
理を行った。なお、表1において、実施例1は一つの中
間熱処理温度、実施例2は二つの中間熱処理温度を設定
し、熱処理を行ったものである。また、比較例として、
1段階で行う熱処理、すなわち、中間熱処理温度を設け
ない熱処理も行った。比較例についても合わせて表1に
示す。In the heat treatment, the synthetic quartz glass having the fictive temperature of 1220 ° C. (initial fictive temperature) is converted into a synthetic quartz glass having the fictive temperature of 1000 ° C. (target fictive temperature). The heat treatment was performed stepwise under the conditions shown in FIG. In Table 1, in Example 1, one intermediate heat treatment temperature was set, and in Example 2, two intermediate heat treatment temperatures were set, and heat treatment was performed. As a comparative example,
Heat treatment performed in one stage, that is, heat treatment without an intermediate heat treatment temperature was also performed. Table 1 also shows comparative examples.
【0026】[0026]
【表1】 実施例1は、中間仮想温度を1050℃とし、中間熱処理温
度として1040℃で、20時間保持したのち、最終熱処理温
度990℃で80時間保持する2段階熱処理を行い、目標仮
想温度を得たものである。このとき、目標仮想温度を有
する合成石英ガラスを得るまでかかった時間の総計は10
0時間であった。なお、最終的に得られた仮想温度は100
7℃と目標仮想温度の1000℃とよく一致していた。[Table 1] In Example 1, the intermediate virtual temperature was set to 1050 ° C, the intermediate heat treatment temperature was maintained at 1040 ° C for 20 hours, and then the two-stage heat treatment was performed at the final heat treatment temperature of 990 ° C for 80 hours to obtain the target virtual temperature. It is. At this time, the total time taken to obtain the synthetic quartz glass having the target virtual temperature is 10
It was 0 hours. Note that the finally obtained virtual temperature is 100
7 ° C and the target virtual temperature of 1000 ° C were in good agreement.
【0027】同様に、実施例2では、中間熱処理温度と
して1090℃、1030℃の2つを設け、それぞれの温度で、
4時間、13時間保持し、その後、最終熱処理温度として9
90℃で、78時間保持する3段階熱処理を行った。このと
き、目標仮想温度を有する合成石英ガラスを得るまでの
時間の総計は95時間であった。Similarly, in Example 2, two intermediate heat treatment temperatures of 1090 ° C. and 1030 ° C. were provided, and at each temperature,
Hold for 4 hours and 13 hours, then 9 as final heat treatment temperature
A three-stage heat treatment was performed at 90 ° C. for 78 hours. At this time, the total time required to obtain the synthetic quartz glass having the target virtual temperature was 95 hours.
【0028】一方、これに対し、中間仮想温度を設けず
に最終仮想温度を1000℃まで減少させた比較例1、2に
ついては、それぞれ990℃と1000℃で保持したところ、
目標仮想温度を有する合成石英ガラスを得るまでそれぞ
れ140時間及び200時間かかった。On the other hand, in Comparative Examples 1 and 2 in which the final virtual temperature was reduced to 1000 ° C. without providing the intermediate virtual temperature, the temperature was maintained at 990 ° C. and 1000 ° C., respectively.
It took 140 hours and 200 hours respectively to obtain the synthetic quartz glass with the target virtual temperature.
【0029】以上の結果から、中間仮想温度を設け、段
階的に熱処理を行った場合、比較的短い保持時間で所望
の温度まで仮想温度を下げることができることが分か
る。From the above results, it is understood that when the intermediate virtual temperature is provided and the heat treatment is performed stepwise, the virtual temperature can be lowered to a desired temperature in a relatively short holding time.
【0030】[0030]
【発明の効果】本発明に係る合成石英ガラスの熱処理方
法は、熱処理を行う際、合成石英ガラスを中間熱処理温
度に保持し、段階的に仮想温度を低下させ、目標仮想温
度を有する合成石英ガラスを得るため、直接目標仮想温
度を得るために、最終熱処理温度で保持する熱処理方法
に比べ、処理時間を短縮でき、生産性を高めることがで
きる。According to the heat treatment method for synthetic quartz glass according to the present invention, when performing the heat treatment, the synthetic quartz glass is maintained at the intermediate heat treatment temperature, the fictive temperature is reduced step by step, and the synthetic quartz glass having the target fictive temperature is obtained. Therefore, in order to directly obtain the target virtual temperature, the processing time can be shortened and the productivity can be increased as compared with a heat treatment method in which the target heat treatment temperature is maintained.
フロントページの続き (72)発明者 福島 謙輔 兵庫県尼崎市扶桑町1番8号 住友金属工 業株式会社エレクトロニクス技術研究所内 Fターム(参考) 4G014 AH21 AH23 Continued on the front page (72) Inventor Kensuke Fukushima 1-8 Fuso-cho, Amagasaki-shi, Hyogo Sumitomo Metal Industries, Ltd. Electronics Technology Research Laboratory F-term (reference) 4G014 AH21 AH23
Claims (2)
成石英ガラスの熱処理方法であって、初期仮想温度と目
標仮想温度との間に、1以上の中間仮想温度を設定し、
合成石英ガラスを前記中間仮想温度に対応する中間熱処
理温度に保持し、順次段階的に中間仮想温度を低下させ
た後、最終熱処理温度で保持し、目標仮想温度を得るこ
とを特徴とする合成石英ガラスの熱処理方法。1. A synthetic quartz glass heat treatment method for lowering a virtual temperature of a synthetic quartz glass, wherein one or more intermediate virtual temperatures are set between an initial virtual temperature and a target virtual temperature.
Synthetic quartz characterized by holding the synthetic quartz glass at an intermediate heat treatment temperature corresponding to the intermediate virtual temperature, sequentially decreasing the intermediate virtual temperature, and then maintaining the final heat treatment temperature to obtain a target virtual temperature. Heat treatment method for glass.
および/または最終熱処理温度が目標仮想温度より低い
ことを特徴とする請求項1に記載の合成石英ガラスの熱
処理方法。2. An intermediate heat treatment temperature lower than an intermediate virtual temperature.
The method according to claim 1, wherein the final heat treatment temperature is lower than the target virtual temperature.
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005022954A (en) * | 2003-04-03 | 2005-01-27 | Asahi Glass Co Ltd | Silica glass containing tio2 and its manufacturing method |
JP2005104820A (en) * | 2003-04-03 | 2005-04-21 | Asahi Glass Co Ltd | SILICA GLASS CONTAINING TiO2 AND PROCESS FOR PRODUCTION THEREOF |
DE102007019154A1 (en) * | 2007-04-20 | 2008-10-23 | Heraeus Quarzglas Gmbh & Co. Kg | Process for the production of an optical component of synthetic quartz glass with increased radiation resistance, as well as blank for the production of the component |
JP2013227225A (en) * | 2003-04-03 | 2013-11-07 | Asahi Glass Co Ltd | SILICA GLASS CONTAINING TiO2 |
-
2000
- 2000-10-10 JP JP2000309507A patent/JP2002121038A/en active Pending
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005022954A (en) * | 2003-04-03 | 2005-01-27 | Asahi Glass Co Ltd | Silica glass containing tio2 and its manufacturing method |
JP2005104820A (en) * | 2003-04-03 | 2005-04-21 | Asahi Glass Co Ltd | SILICA GLASS CONTAINING TiO2 AND PROCESS FOR PRODUCTION THEREOF |
US8329604B2 (en) | 2003-04-03 | 2012-12-11 | Asahi Glass Company, Limited | Silica glass containing TiO2 and process for its production |
JP2013227225A (en) * | 2003-04-03 | 2013-11-07 | Asahi Glass Co Ltd | SILICA GLASS CONTAINING TiO2 |
DE102007019154A1 (en) * | 2007-04-20 | 2008-10-23 | Heraeus Quarzglas Gmbh & Co. Kg | Process for the production of an optical component of synthetic quartz glass with increased radiation resistance, as well as blank for the production of the component |
US7980098B2 (en) | 2007-04-20 | 2011-07-19 | Heraeus Quarzglas Gmbh & Co. Kg | Method for producing an optical component of synthetic quartz glass with enhanced radiation resistance, and blank for producing the component |
DE102007019154B4 (en) * | 2007-04-20 | 2012-07-26 | Heraeus Quarzglas Gmbh & Co. Kg | Method for producing a synthetic quartz glass optical component with increased radiation resistance |
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