JPH075332B2 - Quartz glass base material for light transmissive body, quartz glass ingot mainly for manufacturing the base material, and light transmissive body formed using the base material - Google Patents
Quartz glass base material for light transmissive body, quartz glass ingot mainly for manufacturing the base material, and light transmissive body formed using the base materialInfo
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- JPH075332B2 JPH075332B2 JP5606489A JP5606489A JPH075332B2 JP H075332 B2 JPH075332 B2 JP H075332B2 JP 5606489 A JP5606489 A JP 5606489A JP 5606489 A JP5606489 A JP 5606489A JP H075332 B2 JPH075332 B2 JP H075332B2
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Description
【発明の詳細な説明】 「産業上の利用分野」 本発明は、高出力の赤外光、可視光、紫外光に対し高均
質性と耐久性を保証し得るレンズ、ウインドウ、ミラ
ー、プリズム、フィルター等の光透過体、該透過体を製
造する為の光透過体用ガラス母材、該母材を製造する為
の石英ガラス素塊に係り、特にエキシマレーザ発振装
置、リソグラフィー用レーザ露光装置、レーザCVD装
置、レーザ加工装置、レーザ医療装置等の紫外線波長域
のレーザを利用した各種装置に用いるレーザ光用透過体
として好適な光透過体と、該透過体を製造する為の母
材、及び主とてして母材の出発材として機能する石英ガ
ラス素塊に関する。DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a lens, a window, a mirror, a prism, which can ensure high homogeneity and durability against high-power infrared light, visible light, and ultraviolet light. A light transmissive body such as a filter, a glass base material for a light transmissive body for manufacturing the transmissive body, and a quartz glass ingot for manufacturing the base material, particularly an excimer laser oscillator, a laser exposure apparatus for lithography, A laser CVD device, a laser processing device, a light transmissive body suitable as a laser light transmissive body used in various devices using a laser in the ultraviolet wavelength range such as a laser medical device, and a base material for manufacturing the transmissive body, and The present invention mainly relates to a quartz glass ingot that functions as a starting material for a base material.
「従来の技術」 高純度の石英ガラスは他の光学ガラスに比較して光透過
率が高く且つ歪のない高均質なレンズやミラー部材等の
光学用光透過体を得る事が出来る為に、リソグラフィー
用レーザ露光装置その他の高解像度を必要とする各種装
置の光透過体として多用されている。"Prior Art" High-purity quartz glass has a higher light transmittance than other optical glasses, and it is possible to obtain highly homogeneous optical transmissive bodies such as lenses and mirror members without distortion. It is widely used as a light transmitting body for a laser exposure device for lithography and other various devices that require high resolution.
そしてこの種の光透過体を製造する為の母材は一般によ
り高純度化を図る為に、例えば四塩化珪素を酸水素炎中
で反応させて形成される合成石英ガラスを用い、該合成
石英ガラスを略円柱状、円板状、又は球状等の所望形状
に成型した後、1000℃前後の高温で加熱し、ついで徐冷
を行う事により内部歪を除去し均質化を図っている。
（尚、本願では加熱−徐冷前後の石英ガラス塊の状態を
区別する為に、加熱−徐冷前のガラス塊を石英ガラス素
塊、加熱−徐冷後必要に応じてその周縁域位を研削して
半製品化されたガラス塊を石英ガラス母材として呼称
し、更に該母材を用いてレンズ、ウインド、エタロン板
等に製品化又は半製品化したものを光透過体と呼称す
る。） しかしながら例え前記徐冷速度を極力遅くしても、外気
と接する周縁側と中心域位側の徐冷速度を均一化しなが
ら徐冷する事は不可能であり、該徐冷中高温状態にある
ガラス素塊の中心域より周縁域の冷却速度が必然的に早
くなってしまい、いわゆる中心域より周縁側に向け同心
状にして且つその断面内における仮想温度（Fictve tem
pertuve）分布が中心域から外縁部に向ってなめらかに
大きくなる仮想温度値を示す、上に凹型の曲線となって
しまう。The base material for producing this type of light transmissive body is generally made of synthetic quartz glass formed by reacting silicon tetrachloride in an oxyhydrogen flame in order to achieve higher purity. After molding the glass into a desired shape such as a substantially columnar shape, a disk shape, or a spherical shape, the glass is heated at a high temperature of about 1000 ° C. and then annealed to remove the internal strain to homogenize the glass.
(In the present application, in order to distinguish the states of the quartz glass block before and after heating-slow cooling, the glass block before heating-slow cooling is a quartz glass blank, and after heating-slow cooling, the peripheral region thereof may be changed as necessary. A glass lump that has been ground into a semi-finished product is referred to as a quartz glass base material, and a lens, window, etalon plate or the like that has been commercialized or semi-manufactured using the base material is referred to as a light transmitting body. However, even if the slow cooling rate is slowed down as much as possible, it is impossible to perform slow cooling while equalizing the slow cooling rates on the peripheral side and the central zone side in contact with the outside air. The cooling rate in the peripheral area is inevitably higher than that in the central area of the lump, so that the so-called imaginary temperature (Fictve tem
pertuve) distribution shows a fictive temperature value that gradually increases from the central region toward the outer edge, resulting in a concave curve.
尚、室温における石英ガラスの密度屈折率等の特性値は
そのガラスが過去に高温度域にてなじまされた時の温度
条件によって決定されていると推定される。そしてこの
特性値が決定された時の温度を仮想温度という。It is estimated that the characteristic values such as the density and refractive index of the quartz glass at room temperature are determined by the temperature conditions when the glass was soaked in the high temperature region in the past. The temperature at which this characteristic value is determined is called the fictive temperature.
そして前記のような仮想温度分布差が生じたまま室温状
態にまで冷却すると、組成上理想的に均一なガラス素塊
を用いて前記加熱−徐冷処理を行ったとしても、該処理
により形成されたガラス母材の屈折率分布は前記仮想温
度分布に依存してしまう為に、ガラス塊の中心域より周
縁域の屈折率の方が大きい、軸対称で且つ凹型の曲線状
の屈折率分布が生じてしまう。Then, when the glass is cooled to the room temperature state with the virtual temperature distribution difference as described above, even if the heating-slow cooling treatment is performed using a glass lump that is ideally uniform in composition, it is formed by the treatment. Since the refractive index distribution of the glass base material depends on the fictive temperature distribution, the refractive index in the peripheral region is larger than that in the central region of the glass gob, and there is an axisymmetric and concave curved refractive index distribution. Will occur.
従って前記石英ガラス母材の屈折率分布の均一化を図る
為には、石英ガラスの合成による高純度化とともに、そ
の後における前記熱処理時における仮想温度分布の平坦
化を図らねばならないが、特に仮想温度分布の平坦化に
ついては熱処理炉の改良や熱処理温度プログラムの改善
等を図っても、徐冷速度を実質的に無限大に近づけるの
が不可能である以上、その改善には限界があり、結果と
して前記屈折率分布の均質化を図るのは極めて困難であ
る。Therefore, in order to make the refractive index distribution of the quartz glass base material uniform, it is necessary to achieve high purity by synthesizing the quartz glass and flattening the virtual temperature distribution during the subsequent heat treatment. Regarding the flattening of the distribution, even if the heat treatment furnace is improved or the heat treatment temperature program is improved, it is impossible to bring the annealing rate to practically infinity. As a result, it is extremely difficult to make the refractive index distribution uniform.
一方近年、LSIの高集積化が進むに伴い露光波長の短波
長化により、より高解像化を図ったリソグラフィー用レ
ーザ露光装置が提案されているが、前記のような短波長
レーザ光（193〜308nm）特にエキシマレーザ光を用いた
光透過体の屈折率の均一性は従来の水銀灯の使用波長で
あるｇ線（436nm）或いはｉ線（365nm）の場合に比較し
て１桁以上高いものが要求されるが、前記のように光学
的均質性の低い石英ガラス母材から製造された光透過体
では高い屈折率の均一性を得る事は出来ない為に、微細
且つ鮮明な線画像の露光が不可能になる。On the other hand, in recent years, a laser exposure apparatus for lithography has been proposed in which the exposure wavelength is shortened to a higher resolution as the integration density of the LSI is increased. 308 nm) Especially, the uniformity of the refractive index of the light transmissive body using the excimer laser light is one digit or more higher than that of the g-line (436 nm) or i-line (365 nm) which is the wavelength used in the conventional mercury lamp. However, since it is not possible to obtain a high refractive index uniformity in a light-transmitting body manufactured from a quartz glass base material having low optical homogeneity as described above, it is possible to obtain a fine and clear line image. Exposure becomes impossible.
「発明が解決しようとする課題」 かかる欠点を解消する為に本発明者達は先に、前記加熱
−徐冷処理により生じる仮想温度分布の変動幅を許容し
つつ、該仮想温度分布と少なくとも一つの所定断面方向
に沿って形成したOH基濃度分布を効果的に組に合わせる
事により、前記OH基濃度分布と仮想温度分布夫々に起因
して発生する屈折率変動を互いに相殺し、結果として前
記断面方向における屈折率分布の変動幅を抑制した技術
を提案している（特願昭63-254875号）が、本発明者達
は更に研究及び実験を繰り返した結果、より一層屈折率
分布の変動を抑制し得る光透過体を開発し得た。[Problems to be Solved by the Invention] In order to solve such a drawback, the present inventors have previously allowed the fluctuation range of the fictive temperature distribution generated by the heating-slow cooling process and at least one of the fictive temperature distribution. By effectively combining the OH group concentration distributions formed along one of the predetermined cross-sectional directions into a set, the refractive index fluctuations caused by the OH group concentration distribution and the virtual temperature distribution are offset to each other, and as a result, Although a technique has been proposed in which the fluctuation range of the refractive index distribution in the cross-sectional direction is suppressed (Japanese Patent Application No. 63-254875), the inventors of the present invention repeated research and experimentation, and as a result, further changed the refractive index distribution. A light-transmitting body capable of suppressing the above has been developed.
即ち本発明は、短波長レーザ光（193〜308nm）特に高出
力のエキシマレーザ光を利用した各種装置に用いるレー
ザ光用透過体として極めて好適な光透過体、該透過体を
製造する為の母材、及び主として母材の出発材として機
能する石英ガラス素塊を提供する事を目的とする。That is, the present invention is a light transmitter which is very suitable as a laser light transmitter used in various devices using short-wavelength laser light (193 to 308 nm), especially high-power excimer laser light, and a mother material for manufacturing the transmitter. It is intended to provide a quartz glass ingot that functions as a starting material and a starting material for a base material.
「課題を解決する為の手段」 本発明は、屈折率分布の変動要因たる仮想温度差やOH基
その他の不純物濃度差夫々を極力０に近付けて、光透過
体における屈折率の高均一性を得るのではなく、逆に前
記変動要因の温度差又は濃度差を実質的に０、特に仮想
温度差を実質的に０にする事が不可能である為に、前記
変動要因の温度差又は濃度差の発生を許容しつつその分
布状態を夫々適切に規制する事により、前記夫々の分布
状態に起因して発生する屈折率変動を互いに相殺し、結
果として少なくとも一の断面方向における屈折率分布の
変動幅を抑制した点については前記先願技術と同様であ
る。"Means for Solving the Problem" The present invention aims to bring the virtual temperature difference and the difference in the impurity concentration of the OH group and the like, which are the factors of variation of the refractive index distribution, to as close to 0 as possible to achieve high uniformity of the refractive index in the light transmitting body. On the contrary, since it is impossible to make the temperature difference or the concentration difference of the fluctuation factor substantially 0, especially the virtual temperature difference substantially 0, it is impossible to obtain the temperature difference or the concentration of the fluctuation factor. By appropriately controlling the distribution state while allowing the occurrence of a difference, the refractive index fluctuations caused by the respective distribution states are offset each other, and as a result, the refractive index distribution in at least one cross-sectional direction is The fact that the fluctuation range is suppressed is the same as in the prior art.
即ち前記先願発明は、仮想温度差に依存して変動する屈
折率を抑制する為にOH基濃度分布を効果的に組み合わせ
ているが、特に合成石英ガラスの製造過程では、高純度
の四塩化珪素を酸水素炎中で反応させながら合成石英ガ
ラスを製造している為に、結果としてOH基とともに前記
屈折率分布にも影響を与えるCl基も多数存在する為に、
これを無視して屈折率変動の抑制を図る事は困難であ
る。That is, the above-mentioned prior invention effectively combines the OH group concentration distribution in order to suppress the refractive index that fluctuates depending on the virtual temperature difference, but particularly in the manufacturing process of synthetic quartz glass, high-purity tetrachloride is used. Since synthetic quartz glass is produced while reacting silicon in an oxyhydrogen flame, as a result, there are many Cl groups that also affect the refractive index distribution together with OH groups,
It is difficult to ignore this and suppress the fluctuation of the refractive index.
そこで本発明は、屈折率の変動の大きな変動要素となり
易い前記OH基とCL濃度分布及び仮想温度夫々の変動に着
目して、その変動分布を規制する事により前記先願発明
より更に効果的に屈折率変動の抑制を図る事を可能にし
たものである。Therefore, the present invention focuses on the fluctuations of the OH group and the CL concentration distribution and the fictive temperature, which are likely to be large fluctuation factors of the fluctuation of the refractive index, and more effectively than the invention of the prior application by regulating the fluctuation distribution. It is possible to suppress the fluctuation of the refractive index.
即ち本発明は第１図に示すように、OH基濃度分布とCl濃
度分布を、母材中心域から周縁域に移行するに連れ変位
点が生じる事なく順次変化するようにした合成石英ガラ
スを製造し、必要に応じ該石英ガラスを前記濃度分布と
平行する面内に沿って切断して円柱状、円板状または球
状素塊を形成した後、該素塊を、前記両濃度分布に依存
して形成される屈折率分布（Ｂ）と対応する断面方向に
形成される仮想温度分布をもって加熱−放冷処理をする
事により、前記夫々の変動要素に起因して発生する屈折
率分布変動（B,C）を互いに相殺し、この結果均一性の
屈折率分布（Ａ）を有する石英ガラス母材を得る事が出
来るものである。That is, according to the present invention, as shown in FIG. 1, a synthetic quartz glass in which the OH group concentration distribution and the Cl concentration distribution are sequentially changed without a displacement point as the base material is moved from the central region to the peripheral region After manufacturing, if necessary, the quartz glass is cut along a plane parallel to the concentration distribution to form a cylindrical, disc-shaped, or spherical conglomerate, and the conglomerate depends on both concentration distributions. By performing the heating-cooling process with the virtual temperature distribution formed in the cross-sectional direction corresponding to the refractive index distribution (B) formed as described above, the refractive index distribution fluctuation (caused by each of the fluctuation elements is generated ( B and C) are offset from each other, and as a result, a quartz glass base material having a uniform refractive index distribution (A) can be obtained.
そして、本発明は前記石英ガラス母材のみならず、主と
して母材の出発材として機能する石英ガラス素塊、及び
前記母材に基づいて製造された光透過体夫々においてク
レーム化し、前記目的を達成する為に必要な技術思想の
明瞭化を図っている。And, the present invention claims not only the quartz glass base material but also a quartz glass ingot mainly functioning as a starting material of the base material and a light transmissive body manufactured based on the base material, thereby achieving the above object. We are trying to clarify the technical ideas necessary for doing so.
「作用」 本発明の作用を第１図に基づいて詳細に説明する。"Operation" The operation of the present invention will be described in detail with reference to FIG.
前記したように高純度で且つ均一組成の合成石英ガラス
素塊を用いて加熱−徐冷処理を行った場合は、屈折率分
布は前記仮想温度分布に依存してしまう為に、ガラス塊
の中心域より周縁域のに移行するに連れ順次屈折率が大
である曲線、例えば（Ｃ）に示すような軸対称で且つ凹
型曲線状の屈折率分布が生じてしまう。As described above, when the heating-slow cooling treatment is performed using the synthetic quartz glass ingot of high purity and uniform composition, the refractive index distribution depends on the virtual temperature distribution, and thus the center of the glass ingot A curve having a larger refractive index as it moves from the region to the peripheral region, for example, an axially symmetric and concave curved refractive index distribution as shown in FIG.
そこで前記屈折率分布を相殺し、（Ａ）に示すような平
坦な屈折率分布を得る為には、加熱処理前の石英ガラス
素塊の屈折率分布を（Ｂ）のような、母材中心域から周
縁域に移行するに連れ順次小になるよう軸対称で且つ凸
型曲線状の分布形状にすればよい。Therefore, in order to cancel the above-mentioned refractive index distribution and obtain a flat refractive index distribution as shown in (A), the refractive index distribution of the quartz glass ingot before the heat treatment should be such as shown in (B). It is sufficient to form a convex curvilinear distribution shape that is axially symmetric so that it becomes smaller gradually as it moves from the region to the peripheral region.
即ち請求項５）において提案する石英ガラス素塊は前記
着眼に基づくものであり、OH基濃度分布とCl濃度分布
を、母材中心域から周縁域に移行するに連れ変位点が生
じる事なく順次変化させ、これにより前記断面内におけ
る屈折率分布を（Ｂ）のような分布形状にした点にあ
る。That is, the quartz glass ingot proposed in claim 5) is based on the above-mentioned viewpoint, and the OH group concentration distribution and the Cl concentration distribution are sequentially shifted from the central region of the base metal to the peripheral region without generating displacement points. The refractive index distribution in the cross section is changed to a distribution shape as shown in FIG.
尚OH基濃度分布と屈折率分布は第１図に示すように逆比
例関係にあり、又Cl濃度分布と屈折率分布は正比例関係
にある為に、第１図No.1,No.2及びNo.3に示すようにそ
の組み合わせ及び曲率カーブを任意に設定する事によ
り、前記仮想温度分布に依存する屈折率分布（Ｃ）に対
応する屈折率分布（Ｂ）形成が容易であり、これにより
本願の効果を円滑に達成する事が可能となる。Since the OH group concentration distribution and the refractive index distribution are in inverse proportion as shown in Fig. 1, and the Cl concentration distribution and the refractive index distribution are in direct proportion, the results are shown in Fig. 1 No. 1, No. 2 and By setting the combination and the curvature curve arbitrarily as shown in No. 3, it is easy to form the refractive index distribution (B) corresponding to the refractive index distribution (C) depending on the virtual temperature distribution. It is possible to smoothly achieve the effect of the present application.
そして前記素塊を（Ｃ）に示すような屈折率分布を得る
べく加熱−徐冷処理を行う事により（Ａ）に示すような
平坦な屈折率分布を有する石英ガラス母材を得る事が出
来る。Then, by subjecting the agglomerate to heating-gradual cooling treatment so as to obtain a refractive index distribution as shown in (C), a quartz glass base material having a flat refractive index distribution as shown in (A) can be obtained. .
これが請求項１）に記載された発明である。This is the invention described in claim 1).
更に又請求項７）及び８）に記載された発明は、前記母
材を加工する事により形成されたレンズその他の光透過
体、好ましくはレーザ光用透過体に関するもので、 少なくとも前記OH基及びCl濃度分布を有する断面方向か
ら直交する面方向にレーザー光入射面を設定した点を第
１の特徴とし、又光透過体２の場合は第２図に示すよう
に前記母材１の一部を使用するものである為に、前記濃
度分布の極大又は極小点が中心域にあるとは限らず第２
図の2A,2Cに示すように極大又は極小点さえない場合も
ある。そこで第２の特徴とする所は、前記母材のOH基及
びClの濃度分布が凸曲線又は凹曲線であっても入射面と
直交する面内における最少濃度領域から最大濃度領域に
至る濃度分布は、変異点をもつことなく順次大になる為
に、これを第２の特徴にしている。Furthermore, the invention described in claims 7) and 8) relates to a lens or other light transmissive body, preferably a laser light transmissive body formed by processing the base material, and at least the OH group and The first feature is that the laser light incident surface is set in a plane direction orthogonal to the cross-sectional direction having the Cl concentration distribution, and in the case of the light transmitting body 2, a part of the base material 1 as shown in FIG. Since the maximum and minimum points of the concentration distribution are not always in the central region, the second
In some cases, there is no maximum or minimum point as shown in 2A and 2C of the figure. Therefore, the second feature is that even if the concentration distribution of the OH group and Cl of the base material is a convex curve or a concave curve, the concentration distribution from the minimum concentration region to the maximum concentration region in the plane orthogonal to the incident surface Has a second feature because it gradually increases without having a mutation point.
これにより前記透過体の光使用領域における屈折率分布
変動幅（Δｎ）を２×10-6以下に設定し、これにより前
記のような短波長レーザ光（193〜308nm）特にエキシマ
レーザ光用透過体として極めて好適な光透過体を提供し
得る。且つレーザ光用透過体として好ましい透過体を得
る事が出来る。As a result, the fluctuation range (Δn) of the refractive index distribution in the light use region of the transparent body is set to 2 × 10 −6 or less, whereby the short wavelength laser light (193 to 308 nm) as described above, especially for excimer laser light is transmitted. It is possible to provide a light transmitting body which is extremely suitable as a body. Moreover, it is possible to obtain a preferable transparent body as a transparent body for laser light.
また、耐レーザー光性の点からは該石英ガラス組織中に
含まれるOH基とCl濃度分布差を60ppm以下に設定するの
が好ましい。Further, from the viewpoint of laser light resistance, it is preferable to set the difference in the concentration distribution of OH groups and Cl contained in the quartz glass structure to 60 ppm or less.
「実施例」 次に製造手順に従って、本発明の好ましい実施例を説明
する。"Example" Next, a preferred example of the present invention will be described according to a manufacturing procedure.
先ず酸水素炎加水分解法より、高純度の四塩化珪素を酸
水素炎中で反応させながら円柱状の合成石英ガラス１′
を製造するとともに、前記両ガスの混合比を調整して円
柱軸に対して、ほぼ直交する断面におけるOH基濃度によ
り決定される屈折率分布（B-1）とCl濃度により決定さ
れる屈折率分布（B-2）の合算された屈折率分布（Ｂ）
が中心域で極大値を示し、外縁部に移行するに従いなめ
らかに小さい値を示す曲線、具体的には極大点が中心域
にある上に軸対称の凸曲線になるように制御する。First of all, according to the oxyhydrogen flame hydrolysis method, high purity silicon tetrachloride is reacted in an oxyhydrogen flame to produce a cylindrical synthetic quartz glass 1 '.
And the refractive index distribution (B-1) determined by the OH group concentration and the refractive index determined by the Cl concentration in a cross section substantially orthogonal to the cylinder axis by adjusting the mixing ratio of the two gases. Refractive index distribution (B) that is the sum of the distributions (B-2)
Indicates a maximum value in the central region and a value that smoothly decreases as it moves to the outer edge portion, specifically, the maximum point is in the central region and is controlled so as to be an axisymmetric convex curve.
尚、前記合成石英ガラス素塊中のOH基濃度分布及びCl濃
度分布は原料ガスと酸水素ガスとの混合比率を調整する
のみならず、合成装置のバーナー形状、バーナ位置等を
変化させて制御することが可能である。The OH group concentration distribution and the Cl concentration distribution in the synthetic quartz glass ingot are controlled not only by adjusting the mixing ratio of the raw material gas and the oxyhydrogen gas, but also by changing the burner shape, the burner position, etc. of the synthesizer. It is possible to
又、前記OH基濃度分布及びCl濃度分布の合算された屈折
率分布（Ｂ）における屈折率の極大点とガラス周縁域間
の屈折率変動幅（Δｎ）は後記する、加熱−放冷処理に
よる仮想温度分布と対応させて逆比例的に設定すること
が好ましく、具体的には現状の熱処理による仮想温度分
布差が前記合成石英ガラスの直径によっても異なるが光
使用領域（クリアーアパーチャー）において略４℃以内
の範囲にあることから、OH基濃度分布差（ΔOH）Cl濃度
分布差（ΔCl）夫々を略60ppm以内に設定するのが良
い。The maximum point of the refractive index in the refractive index distribution (B), which is the sum of the OH group concentration distribution and the Cl concentration distribution, and the refractive index fluctuation range (Δn) between the glass peripheral regions are as described below. It is preferable to set in inverse proportion to the virtual temperature distribution. Specifically, although the virtual temperature distribution difference due to the current heat treatment varies depending on the diameter of the synthetic quartz glass, it is approximately 4 in the light use region (clear aperture). Since it is within the range of ℃, it is better to set the difference in OH group concentration distribution (ΔOH) and the difference in Cl concentration distribution (ΔCl) within approximately 60 ppm.
そして、前記のようにして製造された合成石英ガラスは
必要に応じて円柱軸すなわちOH基濃度及びCl濃度分布対
称軸と直交する断面内に沿って切断して第２図に示すよ
うな石英ガラス素塊１を形成する。Then, the synthetic quartz glass manufactured as described above is cut along the columnar axis, that is, in the cross section orthogonal to the symmetrical axis of the OH group concentration and Cl concentration distribution, as required, to obtain the quartz glass as shown in FIG. A lump 1 is formed.
次に、このガラス素塊を電気炉内に設置し、800℃から1
300℃の範囲で所定時間一定温度を保持して、加熱温度
の均一化を図った後、仮想温度分布差が有効域（光透過
域）において略２℃FTになるように制御しながら徐冷を
行う。Next, this glass ingot was placed in an electric furnace and heated from 800 ° C to 1
After maintaining a constant temperature in the range of 300 ℃ for a certain period of time to make the heating temperature uniform, gradual cooling is performed while controlling the virtual temperature distribution difference to be approximately 2 ℃ FT in the effective range (light transmission range). I do.
この際、熱処理温度を800℃から1300℃の範囲とした理
由は、合成石英ガラスの歪点が約1020℃、徐冷点が約11
20℃とされており、1020℃から1120℃のガラス転移領域
を含む温度領域で熱処理することが工業上非常に重要で
有効であると考えられるからである。At this time, the reason for setting the heat treatment temperature in the range of 800 ° C to 1300 ° C is that the synthetic quartz glass has a strain point of about 1020 ° C and an annealing point of about 11 ° C.
It is set at 20 ° C., and it is considered that it is industrially very important and effective to perform heat treatment in a temperature region including a glass transition region of 1020 ° C. to 1120 ° C.
又、仮想温度分布差を略２℃FT以内に設定した理由はこ
れより大に設定すると仮想温度分布曲線が乱れやすくな
るためである。Further, the reason why the virtual temperature distribution difference is set within about 2 ° C. FT is that the virtual temperature distribution curve is likely to be disturbed if the virtual temperature distribution difference is set larger than this.
この結果、前記仮想温度分布による屈曲率分布（Ｃ）が
軸を通る断面内における分布曲線が軸において極小値を
示し、外縁部に移行するに従いなめらかに大きい値を示
す曲線、具体的には極小値が母材中心域にある上に凹型
曲線状になり、OH基とCl濃度分布に基づく屈折率分布
（Ｂ）と対称形状となる。As a result, the distribution curve (C) of the virtual temperature distribution in the section passing through the axis shows a minimum value on the axis, and a curve showing a smoothly large value as it moves to the outer edge portion, specifically, a minimum value. The value is in the central region of the base material and has a concave curve shape, which is symmetrical with the refractive index distribution (B) based on the OH group and Cl concentration distribution.
従って前記熱処理後の石英ガラス塊の周縁域を研削され
た石英ガラス母材の屈折率分布（Ａ）は、前記仮想温度
勾配により形成される屈折率分布（Ｃ）と、OH基とCl濃
度分布により形成される屈折率分布（Ｂ）が加算される
結果、屈折率変動幅（Δｎ）の小さい高均質な石英ガラ
ス母材を得ることができる。Therefore, the refractive index distribution (A) of the quartz glass base material in which the peripheral region of the quartz glass lump after the heat treatment is ground is the refractive index distribution (C) formed by the virtual temperature gradient and the OH group and Cl concentration distribution. As a result of adding the refractive index distribution (B) formed by the above, it is possible to obtain a highly homogeneous silica glass base material having a small refractive index fluctuation width (Δn).
そして、該母材の所望部分を第２図に示すように円柱軸
と断面方向から直交する面方向にレーザー光入射面2aを
設定して切断して必要に応じて研磨その他の加工をし製
品化された光透過体２は、屈折率変動幅（Δｎ）２×10
-6以下という高い均質性を示すことになる。Then, as shown in FIG. 2, a desired portion of the base material is cut by setting a laser light incident surface 2a in a surface direction orthogonal to the cross-sectional direction of the cylinder axis, and polishing or other processing is performed if necessary. The converted light transmitting body 2 has a refractive index fluctuation range (Δn) of 2 × 10
It shows high homogeneity of -6 or less.
「実験結果」 先ず、酸水素炎加水分解法により、原料ガスと酸水素ガ
スとの混合比率を適宜調整しながら合成石英ガラスを製
造した後、その両端を軸と直交する面内に沿って切断す
ることによりφ200×t70mmの円柱状の合成石英ガラス素
塊４ケを作成する。[Experimental Results] First, by the oxyhydrogen flame hydrolysis method, synthetic quartz glass was manufactured while appropriately adjusting the mixing ratio of the raw material gas and the oxyhydrogen gas, and then both ends thereof were cut along a plane orthogonal to the axis. By doing so, four cylindrical synthetic quartz glass ingots of φ200 × t70 mm are prepared.
次に前記４ケのガラス素塊を同時に同一の加熱処理用電
気炉内に設置し、約1100℃の温度条件にて長時間の熱処
理を行った。その後これらのガラス素塊を室温まで冷却
した後、円柱体側面の外周研削と上下面の平面研削を行
いφ150×t40mmのガラス母材を形成し、OH基濃度分布測
定とCl濃度分布測定干渉計による屈折率分布の測定を行
った。Next, the four glass ingots were simultaneously placed in the same electric furnace for heat treatment, and heat-treated for a long time at a temperature of about 1100 ° C. Then, after cooling these glass ingots to room temperature, the side surface of the cylinder was ground and the top and bottom surfaces were ground to form a glass base material of φ150 x t40 mm, and the OH group concentration distribution measurement and Cl concentration distribution measurement interferometer The refractive index distribution was measured by.
その結果、第１図に示すように、前記OH基濃度分布が、
母材中心から周縁部に移行するに連れ順次大になるよう
に形成した凹曲線、又Cl濃度分布が、母材中心域から周
縁域に移行するに連れ、順次小になるように形成した凸
曲線の組み合わせであるサンプルNo.1と、前記OH基濃度
分布とCl濃度分布が夫々前記凹曲線又は夫々前記凸曲線
の組み合わせであるサンプルNO.2及びNo.3では屈折率分
布（Ｂ）と（Ｃ）が相殺されて（Ａ）に示すような屈曲
率変動幅（Δｎ）１×10-6以下という非常に高均質なガ
ラスを得ることができた。As a result, as shown in FIG. 1, the OH group concentration distribution is
A concave curve formed so that it gradually increases as it moves from the center of the base metal to the peripheral edge, and a convex curve that gradually becomes smaller as the Cl concentration distribution moves from the center area of the base material to the peripheral area. Sample No. 1 which is a combination of curves, and the refractive index distribution (B) in Samples No. 2 and No. 3 in which the OH group concentration distribution and the Cl concentration distribution are combinations of the concave curve or the convex curve, respectively. By canceling out (C), it was possible to obtain a very highly homogeneous glass having a bending rate fluctuation range (Δn) of 1 × 10 −6 or less as shown in (A).
しかし、OH基濃度分布が凸曲線とCl濃度分布が凹曲線の
組みに合わせであるサンプNo.4では（Ｂ）と（Ｃ）が逆
に増長されて（Ａ）示すような非常に悪い屈曲率分布と
なってしまった。However, in Sump No. 4 in which the OH group concentration distribution is a combination of a convex curve and the Cl concentration distribution is a concave curve, (B) and (C) are inversely increased and a very bad bend as shown in (A). It has become a rate distribution.
更に、サンプルNo.1,No2及びNo.3について同一条件によ
って、KrFエキシマレーザー（248nm）を照射したとこ
ろ、螢光や内部歪、透過率低下のダメージを受けること
なく耐レーザー性の面で実用的に問題のない事が確認で
きた。Furthermore, when the samples No. 1, No 2 and No. 3 were irradiated with KrF excimer laser (248 nm) under the same conditions, they were practically used in terms of laser resistance without being damaged by fluorescence, internal strain, and decrease in transmittance. It was confirmed that there was no problem.
かかる実験結果より本発明の効果が円滑に達成されてい
る事が理解出来る。From these experimental results, it can be understood that the effects of the present invention are smoothly achieved.
「発明の効果」 以上記載した如く本発明によれば、内部歪を除去しガラ
ス組織の均質化を図る為に行われる加熱−徐冷処理によ
り生じる仮想温度分布を許容しつつ、該仮想温度分布が
存在する場合でも均一な屈折率分布を得る事が出来、特
に193〜308nm前後の高出力のエキシマレーザ光を利用し
た各種装置に用いるレーザ光用透過体として好適な光透
過体を提供する事が出来る。等の種々の著効を有す。"Effects of the Invention" As described above, according to the present invention, while allowing a virtual temperature distribution generated by the heating-slow cooling process performed to remove internal strain and homogenize the glass structure, the virtual temperature distribution is allowed. It is possible to obtain a uniform refractive index distribution even in the presence of, and particularly to provide a light transmissive body suitable as a laser light transmissive body for use in various devices using excimer laser light of high output around 193 to 308 nm. Can be done. It has various remarkable effects.
第１図は本発明の製造過程に対応して屈折率分布の変化
状態を示す作用図、第２図は本発明に用いられる石英ガ
ラス素塊から光透過体までの形状の変化を示す概略図で
ある。FIG. 1 is an action diagram showing a change state of the refractive index distribution corresponding to the manufacturing process of the present invention, and FIG. 2 is a schematic diagram showing a change in shape from the quartz glass ingot to the light transmitting body used in the present invention. Is.
Claims (9)
を加熱し、ついで冷却処理した後、必要に応じてその周
縁部分を研削して形成される光透過体用石英ガラス母材
において、少なくとも一つの所定断面方向に沿って形成
したOH基濃度分布とCl濃度分布、及び前記加熱し、つい
で冷却処理により前記断面方向に沿って形成される仮想
温度分布を効果的に組み合わせる事により、これらの分
布夫々に起因して発生する屈折率変動を互いに相殺し、
結果として前記断面方向における屈折率分布の変動を抑
制した事を特徴とする光透過体用石英ガラス母材1. A quartz glass base material for a light-transmitting body, which is formed by heating a synthetic quartz glass ingot containing OH groups and Cl groups, cooling it, and then grinding the peripheral edge portion as necessary. In, by effectively combining the OH group concentration distribution and the Cl concentration distribution formed along at least one predetermined cross-sectional direction, and the virtual temperature distribution formed along the cross-sectional direction by the heating and then cooling treatment. , Offsetting the refractive index fluctuations caused by each of these distributions,
As a result, the fluctuation of the refractive index distribution in the cross-sectional direction is suppressed, and the quartz glass base material for a light transmitting body is characterized.
周縁域に移行するに連れ順次高くなるような曲線状の分
布に、又Cl濃度を母材中心域から周縁域に移行するに連
れ順次低くなるような曲線状の分布に夫々設定したこと
を特徴とする請求項１）記載の光透過体用石英ガラス母
材2. A curve-shaped distribution in which the OH group concentration and the fictive temperature gradually increase as the temperature shifts from the base metal central region to the peripheral region, and the Cl concentration shifts from the base metal central region to the peripheral region. The quartz glass base material for a light-transmitting body according to claim 1), characterized in that each of the distributions is set to have a curved shape that gradually decreases with time.
材中心域から周縁域に移行するに連れ順次高くなるよう
な曲線状の分布に夫々設定したことを特徴とする請求項
１）記載の光透過体用石英ガラス母材3. The OH group concentration, the Cl concentration, and the fictive temperature are set to have curved distributions that gradually increase as the base material moves from the central region to the peripheral region. ) Quartz glass base material for light transmitting element
縁域に移行するに連れ順次低くなるような曲線状の分布
に、又仮想温度を母材中心域から周縁域に移行するに連
れ順次高くなるような曲線状の分布に夫々設定したこと
を特徴とする請求項１）記載の光透過体用石英ガラス母
材4. A curve-shaped distribution in which the OH group concentration and the Cl concentration become gradually lower as the concentration shifts from the central region of the base metal to the peripheral region, and the fictive temperature shifts from the central region of the base metal to the peripheral region. The quartz glass base material for a light-transmitting body according to claim 1), wherein each of the distributions is set to have a curved shape that gradually increases with time.
点が母材中心域にある略軸対称の曲線状の分布に設定す
ることを特徴とする請求項１）記載の光透過体用石英ガ
ラス母材5. The light transmission according to claim 1, wherein the OH group concentration and the Cl concentration are set to a substantially axisymmetric curved distribution having a minimum point or a maximum point in the center region of the base material. Quartz glass base material for body
なり、該ガラス体の選択された一又は複数の断面におけ
るOH基濃度とCl濃度を母材中心域から周縁域に移行する
に連れ変曲点が生じることなく順次変化させ、これによ
り前記断面内における屈折率分布を母材中心域から周縁
域に移行するに連れ順次低くなるような曲線状の分布に
設定したことを特徴とする石英ガラス素塊6. A synthetic quartz glass containing an OH group and a Cl group, wherein the OH group concentration and the Cl concentration in one or a plurality of selected cross sections of the glass body are transferred from the central region of the base material to the peripheral region. It is characterized in that the refractive index distribution in the cross section is set to be a curved distribution that gradually decreases as it shifts from the central region of the base material to the peripheral region thereof, without causing an inflection point. Quartz glass ingot
するに連れ順次高くなるような曲線状の分布に形成し、
かつCl濃度を母材中心域から周縁域に移行するに連れ順
次低くなるような曲線状の分布に形成するか、 又はOH基濃度とCl濃度のいずれも母材中心域から周縁域
に移行するに連れ順次高くなるような曲線状の分布に形
成するか、 若しくはOH基濃度とCl濃度のいずれも母材中心域から周
縁域に移行するに連れ順次低くなるような曲線状の分布
に設定したことを特徴とする石英ガラス素塊7. An OH group concentration is formed in a curved distribution that gradually increases as it moves from the central region of the base material to the peripheral region,
In addition, the Cl concentration is gradually reduced as it shifts from the base metal center region to the peripheral region, or both the OH group concentration and the Cl concentration shift from the base metal center region to the peripheral region. Or the concentration of OH group and Cl both gradually decreased as the concentration of OH group and Cl increased from the central region of the base metal to the peripheral region. Quartz glass ingot characterized by
る光透過体をOH基とCl基を含有する石英ガラスを用いて
形成し、その入射面と直交する面内における最少濃度領
域から最大濃度領域に至るOH基濃度曲線及びCl濃度曲線
を変曲点をもつことなく順次大きい値になるように設定
しつつ、該透過体の光使用領域における屈折率分布変動
幅（Δｎ）を２×10-6以下に設定したことを特徴とする
光透過体8. A light transmissive body that causes reflection, refraction or straight travel of light is formed by using quartz glass containing OH group and Cl group, and from the minimum concentration region to the maximum concentration in a plane orthogonal to the incident surface. While setting the OH group concentration curve and the Cl concentration curve reaching the region to have successively larger values without having an inflection point, the variation range (Δn) of the refractive index distribution in the light use region of the transmissive body is 2 × 10 5. -A light transmitting material characterized by being set to 6 or less
度領域から最大濃度領域に至るOH基濃度分布差とCl濃度
分布差を各々60ppm以下に設定した請求項８）記載の光
透過体9. The light transmissive body according to claim 8, wherein the difference in OH group concentration distribution and the difference in Cl concentration distribution from the minimum concentration region to the maximum concentration region in the plane orthogonal to the incident surface are each set to 60 ppm or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5606489A JPH075332B2 (en) | 1989-03-10 | 1989-03-10 | Quartz glass base material for light transmissive body, quartz glass ingot mainly for manufacturing the base material, and light transmissive body formed using the base material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5606489A JPH075332B2 (en) | 1989-03-10 | 1989-03-10 | Quartz glass base material for light transmissive body, quartz glass ingot mainly for manufacturing the base material, and light transmissive body formed using the base material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02239127A JPH02239127A (en) | 1990-09-21 |
| JPH075332B2 true JPH075332B2 (en) | 1995-01-25 |
Family
ID=13016654
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5606489A Expired - Lifetime JPH075332B2 (en) | 1989-03-10 | 1989-03-10 | Quartz glass base material for light transmissive body, quartz glass ingot mainly for manufacturing the base material, and light transmissive body formed using the base material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH075332B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1319637A3 (en) | 2001-12-11 | 2004-01-28 | Shin-Etsu Chemical Co., Ltd. | Synthetic quartz glass blank |
-
1989
- 1989-03-10 JP JP5606489A patent/JPH075332B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02239127A (en) | 1990-09-21 |
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