JP4320829B2

JP4320829B2 - Manufacturing method of synthetic quartz glass for ultraviolet and member obtained thereby

Info

Publication number: JP4320829B2
Application number: JP08848899A
Authority: JP
Inventors: 誠志藤原; 典男小峯; 宏樹神保
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1999-03-30
Filing date: 1999-03-30
Publication date: 2009-08-26
Anticipated expiration: 2019-03-30
Also published as: JP2000281366A

Description

【０００１】
【発明の属する技術分野】
本発明は石英ガラスの製造方法に関するものであり、特に、紫外線レーザ全般に使用される光学部材用の合成石英ガラスの製造方法及びそれにより製造された石英ガラスに関するものである。
【０００２】
【従来の技術】
従来、シリコン等のウエハ上に集積回路の微細パターンを露光・転写する光リソグラフィー技術においては、ステッパと呼ばれる露光装置が用いられている。このステッパの光源は、近年のＬＳＩの高集積化にともなってｇ線（４３６ｎｍ）からｉ線（３６５ｎｍ）、さらにはＫｒＦ（２４８ｎｍ）やＡｒＦ（１９３ｎｍ）エキシマレーザへと短波長化が進められている。
【０００３】
一般に、ステッパの照明系あるいは投影レンズとして用いられる光学素材としては、ｉ線よりも短い波長領域での高透過率および耐紫外線性が要求されることから、合成石英ガラスが用いられる。
しかしながら、石英ガラスであっても、真空紫外域になると、様々な要因による吸収が生じる。ステッパのような高精度の光学系の場合、このような吸収が微少なものであっても、吸収により生じる発熱や蛍光により光学性能の低下が問題になる。
【０００４】
【発明が解決しようとする課題】
本発明者らは、上記従来の石英ガラスには以下のような問題点があり、特に２００ｎｍ以下の真空紫外線に対する透過率及び耐紫外線に関して未だ十分な特性を達成するには至っていないことを見いだした。すなわち、真空紫外域における光リソグラフィ技術においては、ｉ線やＫｒＦエキシマレーザと比較してエネルギーが高いため、レンズ等の材料に対する負担も極めて大きい。このため、従来の合成石英ガラスを使用したレンズ、光学系の寿命が短く、光学系の性能低下も著しかった。
【０００５】
真空紫外線の一種であるＡｒＦエキシマレーザに対する耐久性には、石英ガラス中に含有される塩素が非常に大きく関与している。石英ガラスに紫外領域の光が作用すると、Ｅ’センターと呼ばれる５．８ｅＶの吸収帯が現れ紫外領域の透過率が著しく低下する。部材中に存在する塩素も５．８ｅＶ吸収帯の前駆体となりうることから極力減少させねばならない。従来から石英ガラスの合成に用いられてきた四塩化ケイ素は、得られた石英ガラス部材中に３０〜１５０ｐｐｍ程度の塩素が含有されてしまうため、完全に塩素を排除した石英ガラスに比べると耐紫外線性という面では劣っている。そのため、近年有機ケイ素化合物を用いた石英ガラスの合成が行われている。しかしながらこれら従来の技術では、有機ケイ素化合物に含まれる炭素のガラス中への残留について何等考慮していない。
【０００６】
また、有機ケイ素化合物は合成時に用いる火炎中で、加水分解反応と同時に酸化反応を起こすため、合成時の雰囲気は酸素過剰雰囲気にする必要がある。しかしながら、このような雰囲気での合成では紫外線耐久性を向上させるために必要な因子である含有水素分子濃度が、低下するという現象が見られる。
そこで本発明は、真空紫外域で光リソグラフィのような高精度な光学系に使用可能な、真空紫外域の高透過率と高度の耐紫外線性を兼ね備えた合成石英ガラスを得ることを目的とする。
【０００７】
【課題を解決するための手段】
そこで本発明らは、有機ケイ素化合物を原料に用いた場合に真空紫外域で高透過率を有し、かつ耐紫外線性を有する石英ガラスを得るための手法について、鋭意研究を行った。その結果、合成によって得られた部材に含有する炭素不純物から派生すると思われるフォルミルラジカル量(X線を0.1kW,22sec照射したときに発生する量)を減少させることが真空紫外域透過率を向上させるために必要な条件であることを見いだした。そのためには、バーナから噴出する有機ケイ素化合物に近い部位から噴出する酸水素ガスの比率をより酸素過剰にすること，全体的にストイキオメトリよりも酸素過剰にすること，バーナから噴出する原料あるいは水素ガスの流速を一定値以上にすることが効果的であることが判った。また、上述の合成条件にて合成を行うと、酸化性雰囲気が強いため、紫外線耐久性を付与する水素分子濃度が小さくなる可能性が大きいため、それを補うべく，それによって得られた石英ガラスに水素雰囲気熱処理をすることが効果的であるという結論に至った。
【０００８】
合成時に使用する酸素・水素ガスの比率を0.53以上にすることにより、原料として用いる有機ケイ素化合物の酸化反応がより促進され、完結するために望ましい。また、不純物、特にアルカリ金属の含有は、真空紫外域の透過率を低下させる一因になることから、水素雰囲気処理はアルカリ不純物の拡散が非常に少ない温度域である５００℃以下、熱処理についてもアルカリ不純物の拡散の非常に少ない酸素分圧０．１ａｔｍ以上かつ歪等の低減が図れる９００℃以上の温度域での処理が望ましい。さらに、第二の管から噴出される水素ガス流速があまり速いと有機ケイ素と酸素との反応が完結しないままガラス化される、すなわちガラス中に含有される炭素量の増大につながり、ひいては透過率の低下が予想されることから、６０ｍ／ｓｅｃ以下であることが望ましい。
【０００９】
よって、本発明においては、有機ケイ素化合物を原料に合成を行う際に用いる酸水素火炎を酸化性雰囲気にして石英ガラスを合成した後に水素雰囲気熱処理を行うことを特徴とする。
また、本発明においては、用いるバーナ構造が中心部に配置されかつ原料を噴出するための第一の管と、該第一の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第二の管と、該第二の管の周囲に同心円状に配置されかつ酸素ガスを噴出するための第三の管と、該第三の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第四の管と、該第三の管の外周と該第四の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第五の管と、該第四の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第六の管と、該第四の管の外周と該第六の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第七の管と、を備えたバーナで、第二・第三の管のガス比率及び第四・第五の管のガス比率を酸素過剰領域に、第六・第七の管のガス比率を水素過剰領域にすることを特徴とする。
【００１０】
【発明の実施の形態】
本発明において、原料として用いる有機ケイ素化合物としては、沸点が170℃以下の化合物、例えばヘキサメチルジシロキサン，メチルトリメトキシシラン，テトラメトキシシラン，オクタメチルシクロテトラシロキサン等が挙げられる。前述のように、真空紫外域の透過率に対して、得られた石英ガラス中に含有している炭素から派生するフォルミルラジカル量が影響している。その全量を低減させるために、本発明では酸化性火炎中で合成を行い、耐紫外線性を付与するために水素雰囲気下で熱処理を行う。
【００１１】
本発明に用いるバーナは、中心部に配置されかつ原料を噴出するための第一の管と、該第一の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第二の管と、該第二の管の周囲に同心円状に配置されかつ酸素ガスを噴出するための第三の管と、該第三の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第四の管と、該第三の管の外周と該第四の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第五の管と、該第四の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第六の管と、該第四の管の外周と該第六の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第七の管と、を備えたバーナである。このバーナは石英ガラス製で、各管から噴出されるガスの流量、流速をそれぞれ独立して制御することが可能である。このような制御は、例えばマスフローコントローラーを用いて行われる。
【００１２】
第一の管には、有機ケイ素化合物が導入される。有機ケイ素化合物自体が液体の場合、ベーパライザにより原料を蒸気化した後、キャリアガスとともにマスフローコントローラーに送られる。キャリアガスとしては、窒素，ヘリウムなどの不活性ガスが用いられる。
本発明における実施例を以下に示す。
【００１３】
実施例，比較例
高純度石英ガラスインゴットは、図に示すような石英ガラス製バーナにて酸素ガス及び水素ガスを表１に示すような流量及び流速で燃焼させ、中心部から原料をキャリアガスで希釈して噴出させる、いわゆる酸水素火炎加水分解法と呼ばれる方法により合成を行った。合成の際、ガラスを積層させる不透明石英ガラス板からなるターゲットを一定周期で回転及び揺動させ、さらに降下を同時に行うことによりインゴットの上部の位置を常時バーナから一定に保った。
【００１４】
【表１】

【００１５】
このようにして複数個のインゴットを合成した。このインゴットから、テストピースを切り出し、研磨をすることにより測定サンプルとした。表２にこの測定の結果を示す。
【００１６】
【表２】

【００１７】
【発明の効果】
以上のように、有機ケイ素化合物を原料に合成を行う際に用いる酸水素火炎を酸化性雰囲気にして石英ガラスを合成した後に水素雰囲気熱処理を行い、その際に用いるバーナ構造が中心部に配置されかつ原料を噴出するための第一の管と、該第一の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第二の管と、該第二の管の周囲に同心円状に配置されかつ酸素ガスを噴出するための第三の管と、該第三の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第四の管と、該第三の管の外周と該第四の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第五の管と、該第四の管の周囲に同心円状に配置されかつ水素ガスを噴出するための第六の管と、該第四の管の外周と該第六の管の内周との間に配置されかつ酸素ガスを噴出するための複数の第七の管と、を備えたバーナで、第二・第三の管のガス比率及び第四・第五の管のガス比率を酸素過剰領域に、第六・第七の管のガス比率を水素過剰領域にすること、また、第一の管から噴出するガスの流速を7m/sec以下及び第二の管から噴出する水素ガス流速を60m/sec以下にすることで、真空紫外域の透過率が高く、紫外線耐久性の高い塩素の含有していない石英ガラスを得ることができる。
【図面の簡単な説明】
【図１】本発明における製造方法のフローチャート
【図２】本実験で使用したバーナの概略図
【図３】ArFエキシマレーザ波長での透過率とX線照射後に生成するフォルミルラジカル濃度との相関
【図４】全酸素ガス量と全水素ガス量との比率とX線照射後に生成するフォルミルラジカル濃度との相関
【図５】全酸素ガス量から原料の燃焼に用いられる酸素ガス量を差し引いた酸素ガス量と全水素ガス量との比率とX線照射後に生成するフォルミルラジカル濃度との相関
【図６】第一の管から噴出するガスの流速とX線照射後に生成するフォルミルラジカル濃度との相関
【図７】第二の管から噴出する水素ガスの流速とX線照射後に生成するフォルミルラジカル濃度との相関[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing quartz glass, and more particularly to a method for producing synthetic quartz glass for optical members used in general for ultraviolet lasers and quartz glass produced thereby.
[0002]
[Prior art]
Conventionally, an exposure apparatus called a stepper is used in an optical lithography technique for exposing and transferring a fine pattern of an integrated circuit onto a wafer such as silicon. The light source of this stepper has been shortened from g-line (436 nm) to i-line (365 nm), and further to KrF (248 nm) and ArF (193 nm) excimer lasers with the recent high integration of LSI. Yes.
[0003]
In general, synthetic quartz glass is used as an optical material used for a stepper illumination system or projection lens because it requires high transmittance and ultraviolet resistance in a wavelength region shorter than i-line.
However, even quartz glass is absorbed by various factors in the vacuum ultraviolet region. In the case of a high-precision optical system such as a stepper, even if such absorption is very small, degradation of optical performance becomes a problem due to heat generation and fluorescence caused by absorption.
[0004]
[Problems to be solved by the invention]
The present inventors have found that the above-described conventional quartz glass has the following problems, and in particular, has not yet achieved sufficient characteristics with respect to transmittance and ultraviolet resistance against vacuum ultraviolet rays of 200 nm or less. . That is, in the photolithographic technique in the vacuum ultraviolet region, since the energy is higher than that of i-line or KrF excimer laser, the burden on materials such as lenses is extremely large. For this reason, the life of lenses and optical systems using conventional synthetic quartz glass is short, and the performance degradation of the optical systems is also remarkable.
[0005]
Chlorine contained in quartz glass is greatly involved in durability against ArF excimer laser, which is a kind of vacuum ultraviolet ray. When light in the ultraviolet region acts on quartz glass, an absorption band of 5.8 eV called E ′ center appears and the transmittance in the ultraviolet region is remarkably lowered. Since chlorine present in the member can also be a precursor of the 5.8 eV absorption band, it must be reduced as much as possible. Since silicon tetrachloride conventionally used for the synthesis of quartz glass contains about 30 to 150 ppm of chlorine in the obtained quartz glass member, it is more resistant to ultraviolet rays than quartz glass completely excluding chlorine. It is inferior in terms of sex. Therefore, in recent years, quartz glass using an organosilicon compound has been synthesized. However, in these conventional techniques, no consideration is given to the residual carbon contained in the organosilicon compound in the glass.
[0006]
In addition, since an organosilicon compound causes an oxidation reaction simultaneously with a hydrolysis reaction in a flame used at the time of synthesis, the atmosphere at the time of synthesis needs to be an oxygen-excess atmosphere. However, in the synthesis in such an atmosphere, there is a phenomenon that the concentration of hydrogen molecules, which is a factor necessary for improving the ultraviolet durability, decreases.
Therefore, the present invention has an object of obtaining a synthetic quartz glass having both high transmittance in the vacuum ultraviolet region and high ultraviolet resistance, which can be used in a high-precision optical system such as photolithography in the vacuum ultraviolet region. .
[0007]
[Means for Solving the Problems]
Therefore, the present inventors conducted extensive research on a technique for obtaining quartz glass having high transmittance in the vacuum ultraviolet region and ultraviolet resistance when an organosilicon compound is used as a raw material. As a result, reducing the amount of formyl radicals (the amount generated when X-rays are irradiated at 0.1 kW for 22 seconds), which is thought to be derived from the carbon impurities contained in the components obtained by synthesis, reduces the vacuum ultraviolet transmittance. I found out that it was a necessary condition for improvement. For that purpose, the ratio of the oxyhydrogen gas ejected from the portion close to the organosilicon compound ejected from the burner should be made to be more oxygen-excessive, the overall oxygen-excess than the stoichiometry, the raw material ejected from the burner or It has been found that it is effective to set the flow rate of hydrogen gas to a certain value or more. In addition, when the synthesis is performed under the above-described synthesis conditions, since the oxidizing atmosphere is strong, there is a high possibility that the concentration of hydrogen molecules imparting ultraviolet durability is small. It was concluded that heat treatment in a hydrogen atmosphere is effective.
[0008]
By setting the ratio of oxygen / hydrogen gas used in the synthesis to 0.53 or more, the oxidation reaction of the organosilicon compound used as a raw material is further promoted and is desirable. In addition, since the inclusion of impurities, particularly alkali metals, contributes to lowering the transmittance in the vacuum ultraviolet region, the hydrogen atmosphere treatment is also performed at a temperature of 500 ° C. It is desirable to perform the treatment in a temperature range of 900 ° C. or higher where the oxygen partial pressure is 0.1 atm or higher with very little diffusion of alkali impurities and distortion can be reduced. Furthermore, if the flow rate of hydrogen gas ejected from the second tube is too high, the reaction between organosilicon and oxygen is vitrified, that is, the amount of carbon contained in the glass is increased, and thus the transmittance. Is expected to be 60 m / sec or less.
[0009]
Therefore, the present invention is characterized in that the heat treatment in the hydrogen atmosphere is performed after the quartz glass is synthesized by using the oxyhydrogen flame used when synthesizing the organosilicon compound as a raw material in an oxidizing atmosphere.
Further, in the present invention, the burner structure to be used is arranged at the center and a first pipe for ejecting the raw material, and is arranged concentrically around the first pipe and for ejecting hydrogen gas. A second pipe, a third pipe arranged concentrically around the second pipe and for ejecting oxygen gas, a concentric circle arranged around the third pipe and hydrogen gas A fourth pipe for jetting, a plurality of fifth pipes arranged between the outer circumference of the third pipe and the inner circumference of the fourth pipe and for jetting oxygen gas, A sixth pipe arranged concentrically around the four pipes and for ejecting hydrogen gas; an oxygen gas arranged between the outer circumference of the fourth pipe and the inner circumference of the sixth pipe; A burner having a plurality of seventh pipes for ejecting oxygen, the gas ratio of the second and third pipes and the gas ratio of the fourth and fifth pipes Linseed area, characterized that you gas ratio of sixth-seventh pipe to the hydrogen excess region.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, examples of the organosilicon compound used as a raw material include compounds having a boiling point of 170 ° C. or less, such as hexamethyldisiloxane, methyltrimethoxysilane, tetramethoxysilane, octamethylcyclotetrasiloxane, and the like. As described above, the amount of formyl radical derived from carbon contained in the obtained quartz glass has an influence on the transmittance in the vacuum ultraviolet region. In order to reduce the total amount, in the present invention, synthesis is performed in an oxidizing flame, and heat treatment is performed in a hydrogen atmosphere in order to impart ultraviolet resistance.
[0011]
The burner used in the present invention includes a first tube disposed at the center and for ejecting the raw material, and a second tube disposed concentrically around the first tube and ejecting hydrogen gas. And a third tube arranged concentrically around the second tube and for ejecting oxygen gas, and arranged concentrically around the third tube and for ejecting hydrogen gas A fourth pipe, a plurality of fifth pipes arranged between the outer circumference of the third pipe and the inner circumference of the fourth pipe and for injecting oxygen gas, and the fourth pipe A sixth tube arranged concentrically around and for ejecting hydrogen gas, and arranged between the outer periphery of the fourth tube and the inner periphery of the sixth tube to eject oxygen gas And a plurality of seventh tubes. This burner is made of quartz glass, and the flow rate and flow rate of gas ejected from each tube can be controlled independently. Such control is performed using, for example, a mass flow controller.
[0012]
An organosilicon compound is introduced into the first tube. When the organosilicon compound itself is liquid, the raw material is vaporized by the vaporizer and then sent to the mass flow controller together with the carrier gas. An inert gas such as nitrogen or helium is used as the carrier gas.
Examples of the present invention are shown below.
[0013]
Examples and Comparative Examples High-purity quartz glass ingots were burned with oxygen gas and hydrogen gas at the flow rates and flow rates shown in Table 1 in a quartz glass burner as shown in the figure, and the raw material was used as a carrier gas from the center. The synthesis was carried out by a so-called oxyhydrogen flame hydrolysis method in which the solution was diluted and ejected. During the synthesis, the target made of an opaque quartz glass plate on which the glass was laminated was rotated and swung at a constant period, and further the descent was performed simultaneously to keep the position of the upper part of the ingot constantly from the burner.
[0014]
[Table 1]

[0015]
Thus, a plurality of ingots were synthesized. A test piece was cut out from this ingot and polished to obtain a measurement sample. Table 2 shows the results of this measurement.
[0016]
[Table 2]

[0017]
【The invention's effect】
As described above, the quartz glass is synthesized using the oxyhydrogen flame used when synthesizing the organosilicon compound as a raw material in an oxidizing atmosphere, and then the hydrogen atmosphere heat treatment is performed, and the burner structure used at that time is arranged in the center. And a first pipe for ejecting the raw material, a second pipe arranged concentrically around the first pipe and for ejecting hydrogen gas, and concentric around the second pipe And a third tube for ejecting oxygen gas, a fourth tube disposed concentrically around the third tube and for ejecting hydrogen gas, and a third tube A plurality of fifth tubes disposed between the outer periphery and the inner periphery of the fourth tube and for ejecting oxygen gas, and concentrically disposed around the fourth tube and ejecting hydrogen gas Between the outer periphery of the fourth tube and the inner periphery of the sixth tube. A burner having a plurality of seventh pipes for injecting oxygen gas, the gas ratio of the second and third pipes and the gas ratio of the fourth and fifth pipes in the oxygen excess region,・ Set the gas ratio of the seventh pipe to the hydrogen excess region, set the flow rate of the gas ejected from the first pipe to 7 m / sec or less and the flow rate of the hydrogen gas ejected from the second pipe to 60 m / sec or less. By doing so, it is possible to obtain quartz glass having high transmittance in the vacuum ultraviolet region and high ultraviolet durability and containing no chlorine.
[Brief description of the drawings]
1 is a flow chart of a manufacturing method in the present invention. FIG. 2 is a schematic diagram of a burner used in this experiment. FIG. 3 is a correlation between transmittance at an ArF excimer laser wavelength and formyl radical concentration generated after X-ray irradiation. [Fig. 4] Correlation between the ratio of the total oxygen gas amount and the total hydrogen gas amount and the concentration of formyl radical generated after X-ray irradiation. [Fig. 5] Subtract the oxygen gas amount used for combustion of the raw material from the total oxygen gas amount. Between the ratio of the amount of dissolved oxygen gas and the total amount of hydrogen gas and the concentration of formyl radical generated after X-ray irradiation [Fig. 6] Flow rate of gas ejected from the first tube and formyl radical generated after X-ray irradiation Correlation with concentration Fig. 7 Correlation between flow rate of hydrogen gas ejected from second tube and concentration of formyl radical generated after X-ray irradiation

Claims

An organosilicon compound is ejected from the burner and hydrolyzed or oxidized in an oxidizing flame containing oxygen and hydrogen to obtain glass fine particles. The glass fine particles are deposited on a heat-resistant target opposite to the burner and simultaneously melted. A synthesis step for obtaining quartz glass substantially free of chlorine,
A heat treatment step of heat-treating the synthetic quartz glass not containing chlorine in an atmosphere containing hydrogen,
The method for producing synthetic quartz glass for ultraviolet , wherein the oxidizing flame is an oxidizing flame having a ratio of the total oxygen gas amount to the total hydrogen gas amount of 0.53 or more.

An organosilicon compound is ejected from the burner and hydrolyzed or oxidized in an oxidizing flame containing oxygen and hydrogen to obtain glass fine particles. The glass fine particles are deposited on a heat-resistant target opposite to the burner and simultaneously melted. A synthesis step for obtaining quartz glass substantially free of chlorine,
A heat treatment step of heat-treating the synthetic quartz glass not containing chlorine in an atmosphere containing hydrogen,
A first pipe with the burner disposed in the center and for ejecting the raw material; a second pipe disposed concentrically around the first pipe and for ejecting hydrogen gas; and A third tube arranged concentrically around the second tube and for ejecting oxygen gas, and a fourth tube arranged concentrically around the third tube and for ejecting hydrogen gas A plurality of fifth tubes disposed between the outer periphery of the third tube and the inner periphery of the fourth tube and for ejecting oxygen gas, and concentrically around the fourth tube And a sixth pipe for ejecting hydrogen gas, and a plurality of second pipes arranged between the outer circumference of the fourth pipe and the inner circumference of the sixth pipe for ejecting oxygen gas. A burner with seven tubes,
Theoretical combustion is the ratio of the hydrogen gas ejected from the second pipe to the oxygen gas ejected from the third pipe, and the ratio of the hydrogen gas ejected from the fourth pipe to the oxygen gas ejected from the fifth pipe Synthetic quartz for ultraviolet light, characterized in that oxygen is higher than the ratio, and the ratio of hydrogen gas ejected from the sixth pipe to oxygen gas ejected from the seventh pipe is higher than the theoretical combustion ratio Glass manufacturing method.

An organosilicon compound is ejected from the burner and hydrolyzed or oxidized in an oxidizing flame containing oxygen and hydrogen to obtain glass fine particles. The glass fine particles are deposited on a heat-resistant target opposite to the burner and simultaneously melted. A synthesis step for obtaining quartz glass substantially free of chlorine,
A heat treatment step of heat-treating the synthetic quartz glass not containing chlorine in an atmosphere containing hydrogen,
A first pipe with the burner disposed in the center and for ejecting the raw material; a second pipe disposed concentrically around the first pipe and for ejecting hydrogen gas; and A third tube arranged concentrically around the second tube and for ejecting oxygen gas, and a fourth tube arranged concentrically around the third tube and for ejecting hydrogen gas A plurality of fifth tubes disposed between the outer periphery of the third tube and the inner periphery of the fourth tube and for ejecting oxygen gas, and concentrically around the fourth tube And a sixth pipe for ejecting hydrogen gas, and a plurality of second pipes arranged between the outer circumference of the fourth pipe and the inner circumference of the sixth pipe for ejecting oxygen gas. A burner with seven tubes,
The ratio (c / d) of the oxygen gas amount (c), which is obtained by subtracting the combustion amount of the organosilicon compound ejected from the first pipe from the total oxygen gas amount, to the total hydrogen gas amount (d) is 0.48 or more. A method for producing a synthetic quartz glass for ultraviolet light.