JPH07187684A - Production of quartz glass and quartz glass made by the same - Google Patents

Abstract

PURPOSE:To provide quartz glass having high uniformity and high ultraviolet transmittance and ultraviolet resistance by adjusting a ratio between gaseous oxygen and gaseous hydrogen jetted from combustion annular pipes and combustion circular pipes of a prescribed burner. CONSTITUTION:A raw material circular pipe 7 for jetting gaseous Si compounds is arranged in the central part, and plural combustion annular pipes 1 or 2 for jetting gaseous O2 and gaseous H2 and combustion circular pipes 5 for jetting gaseous O2 are concentrically arranged around the pipe 7 to provide a multiple pipe burner made of quartz glass. Next, a ratio between gaseous O2 and gaseous H2 jetted from plural annular pipes 1 or 2 except the outermost one is taken as the theoretical equivalent one, and the ratio is compared with a ratio between gaseous O2 and the gaseous H2 jetted from the pipes 5 inside the outermost annular pipe 1 or 2, and each gas is jetted from the burner so that hydrogen may be in excess. Then, quartz glass powder is deposited on a target and vitrified to form an ingot, allowing quartz glass to be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field 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 ultraviolet lasers in general and quartz glass produced thereby. is there.

[0002]

2. Description of the Related Art Conventionally, an exposure apparatus called a stepper has been 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 is g-line (436 nm) to i-line (365 nm), and further K
Shorter wavelengths are being promoted to rF (248 nm) and ArF (193 nm) excimer lasers.

Generally, the optical glass used as an illumination system or a projection lens of a stepper has a low light transmittance in a wavelength region shorter than the i-line, and therefore synthetic quartz glass or CaF ₂ (fluorite) is used instead of the conventional optical glass. It has been proposed to use a fluoride single crystal such as stone. The optical system mounted on the stepper is composed of a combination of many lenses, and even if the amount of decrease in transmittance per lens is small, it is added up by the number of lenses used, and the amount of light on the irradiation surface is increased. Therefore, high transmittance is required for the material. Further, as the wavelength used becomes shorter, the image forming performance becomes extremely poor even if the refractive index distribution is very small.

As described above, quartz glass used as an optical element for ultraviolet lithography is required to have high transmittance of ultraviolet rays and high homogeneity of refractive index. However, the commercially available synthetic quartz glass is insufficient in quality such as homogeneity and ultraviolet resistance, and cannot be used in the above-described precision optical equipment. For this reason,
Up to now, secondary treatment for homogenization (Japanese Patent Publication No. 03-17775,
JP-A 64-28240) and improvement of laser resistance by heat treatment in pressurized hydrogen gas (JP-A 03-109233) have been proposed.

These methods are methods in which silica glass is once synthesized and then subjected to secondary treatment in order to improve optical performance.

[0006]

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 remarkably decreases. It is reported that if hydrogen molecules are present here, hydrogen molecules terminate the E'center, and the amount of reduction in the transmittance of the quartz glass in the ultraviolet region can be drastically reduced (US Pat. No. 50).
86352).

As described above, the hydrogen molecules in the quartz glass have an effect of remarkably improving the ultraviolet durability.
However, the conventional technique as described above has a problem that, in order to introduce hydrogen molecules into the quartz glass, heat treatment (hydrogen treatment or the like) must be performed again after synthesizing the quartz glass once. That is, in this method, heat is applied at least twice until the introduction of hydrogen molecules. Therefore, there are problems that the productivity is lowered and the cost of the final product is increased. Further, in order to introduce hydrogen molecules in the secondary treatment, the treatment must be carried out in a hydrogen atmosphere, and there is a risk of ignition and explosion. Further, there is a problem that a new absorption band or a new emission band is generated due to the inclusion of impurities and the exposure to the reducing atmosphere by the pressure heat treatment at a high temperature.

In addition, in recent years, as the lens diameter used in the photolithography technique becomes larger, in order to uniformly introduce hydrogen molecules into the large-diameter silica glass optical member by the secondary treatment,
Considering the diffusion coefficient, it has a considerably long time. Further, when it is considered to be used as a lens for ultraviolet lithography, the energy density becomes the highest, so that there is a problem that the hydrogen concentration in the central portion, which requires a higher hydrogen concentration, becomes lower than that in the peripheral portion. .

The present invention contains these hydrogen molecules in an amount necessary for solving these problems and suppressing a decrease in transmittance due to ultraviolet light irradiation, and does not contain bubbles, foreign matters, striae, strain, etc. An object of the present invention is to provide a method for producing a quartz glass that is homogeneous, has high transmittance, and has durability against ultraviolet rays.

[0010]

In view of the above, the present invention has focused its attention on the fact that the introduction of hydrogen molecules at the time of synthesis eliminates the need for secondary treatment, and has conducted intensive research. As a result, a high concentration of hydrogen molecules was introduced during the synthesis by making the proportion of the combustion gas around the raw material circular tube that ejects the Si compound gas in the center of the burner excessive, and the secondary treatment was performed. I found it unnecessary. Further, regarding the proportion of the combustion gas ejected from the outermost combustion ring-shaped tube and the combustion circular tube inside thereof, if the hydrogen excess atmosphere is too strong, the transmittance of the synthesized quartz glass becomes low. I understood it.

Therefore, in the present invention, the "proportion of oxygen gas and hydrogen gas ejected from a plurality of combustion ring-shaped tubes excluding the outermost portion" is defined as the theoretical equivalence ratio and "the outermost combustion ring-shaped tube and its It is assumed that the amount of hydrogen is excessive in comparison with the “proportion of oxygen gas and hydrogen gas ejected from the internal combustion circular tube”. Alternatively, in the present invention, “the ratio of oxygen gas and hydrogen gas ejected from a plurality of combustion ring-shaped tubes excluding the outermost portion” is compared with the theoretical equivalence ratio to make hydrogen excess, and The ratio of the oxygen gas and the hydrogen gas ejected from the tube and the combustion circular tube inside the tube is equal to or more than the theoretical equivalent ratio.

[0012]

As described above, as a method of introducing hydrogen molecules, a secondary treatment is generally performed by a hot isostatic press (HIP), a high temperature high pressure atmosphere heat treatment furnace, or the like. The generation of oxygen-deficient defects during this secondary treatment, or a problem when used as an ultraviolet optical material due to the inclusion of impurities such as Na,
Devitrification may occur depending on the generation of a new absorption band and the processing temperature range.

The manufacturing method of the present invention does not have such a demerit. Further, while it is difficult to introduce hydrogen into the large-diameter quartz glass member by the secondary treatment,
According to the production method of the present invention, since hydrogen molecules are introduced during synthesis, it is possible to maintain a high concentration of hydrogen molecules regardless of the diameter of the silica glass. The hydrogen molecule concentration in the quartz glass ingot thus obtained has a comparatively gentle distribution in the central portion in the radial direction, and decreases toward the peripheral portion, that is, a convex distribution. If quartz glass having a convex hydrogen molecule concentration distribution is used as an optical element for ultraviolet lithography, ultraviolet durability is maintained even in the central portion where the energy density is highest.

The mechanism of synthesizing hydrogen by synthesis will be described below. Although the dissolution process of hydrogen molecules in quartz glass during synthesis is not well understood, when the Si compound (raw material) gas injected together with the carrier gas is hydrolyzed into fine particles (quartz glass powder), It is presumed that vitrification occurs while involving a certain proportion of hydrogen molecules. Therefore,
If there is an excess of hydrogen in the portion closer to the center, the probability that hydrogen molecules will dissolve in the silica glass will increase, and the hydrogen molecule concentration should increase. By containing a high concentration of hydrogen molecules by such a method, it becomes possible to improve the ultraviolet durability without considering contamination or danger. However, in this method, it is not a good idea to make the proportion of the combustion gas (the combustion-supporting gas and the combustion-supporting gas) in the outermost portion excessive with hydrogen. Since this part has a much higher gas flow rate than other parts, it is likely to be in a hydrogen excess / oxygen deficient atmosphere, and by synthesizing under such conditions, oxygen deficient type defects such as Si-Si are generated, On the contrary, this causes a decrease in transmittance of 225 nm or less.

The quartz glass produced by the method for producing quartz glass according to the present invention satisfies the optical properties of the refractive index distribution, which directly affect the optical performance of the optical element for photolithography. A close look at the refractive index distribution of quartz glass reveals that it can be separated into a power component, an ass component, a rotationally symmetric component, a gradient component, a random component, etc., and these components overlap to form the entire refractive index distribution. The influence of each of these components on the optical performance is different.

RMS value of wavefront aberration (after power component correction)
Indicates only the component that directly affects the optical performance. After the power component correction, the power component is the same as the error of the radius of curvature. For example, when it is used as a lens, it can be corrected by the curvature of the lens, and can also be easily corrected by the air space of the lens. Therefore, when used in an optical system, it does not directly affect the image quality.

According to the manufacturing method of the present invention, specifically,
The RMS (root mean square) value of the wavefront aberration is 0.02λ or less after power component correction, the homogeneity of the refractive index in the optical axis direction is Δn ≦ 2 × 10 ^-6 without power component correction, and the refraction of the cross section including the incident optical axis Central distribution, with single extreme value distribution, birefringence ≤ 2 nm / cm
Quartz glass such as is obtained respectively. Also,
365nm, 248nm, 1 at any site in quartz glass
Quartz glass with 10 mm internal transmittance of more than 99.9% at 93 nm is obtained. Such quartz glass has not been known yet.

Further, a KrF excimer laser is set to 400 mJ / cm ² pu
After irradiating 10 ⁶ pulses with lse, 10 mm internal transmittance at 248 nm exceeds 99.9%, or ArF excimer laser is irradiated with 100 mJ / cm 2 pulse for 10 ⁶ pulses,
Quartz glass with a 10 mm internal transmittance of more than 99.9% at 193 nm is obtained. This means that the hydrogen concentration of quartz glass obtained by the present invention is 5 × 10 ¹⁷ pieces / anywhere.
cm ³ and towards the central portion is because with a higher hydrogen concentration than the peripheral portion. Such quartz glass is less likely to cause defects generated by ultraviolet irradiation, and satisfies the durability as an optical element for ultraviolet lithography.

This is because the method for producing quartz glass according to the present invention does not require a post-synthesis secondary treatment which adversely affects the optical performance of these materials. These quartz glasses are suitable for use as an optical element for ultraviolet lithography.

[0020]

EXAMPLES Examples of the present invention will be described below. Tables 1 and 2 show manufacturing conditions and physical properties of the quartz glass of Examples and Comparative Examples. Further, Table 3 describes the symbols (◯, Δ, ×) in Tables 1 and 2.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

Example 1 A high purity quartz glass ingot uses a high purity chlorine compound gas of silicon as a raw material,
Oxygen gas and hydrogen gas are burned at the arrangement and flow rates shown in Table 1 by a quartz glass multi-tube burner as shown in FIGS. 2 and 3, and the raw material gas is diluted with a carrier gas and ejected from the center. It was synthesized by a so-called oxyhydrogen flame hydrolysis method or a method called a direct method. During synthesis, a target made of an opaque quartz glass plate on which glass is laminated is rotated and oscillated at a constant cycle, and further descended at the same time to keep the position of the upper part of the ingot at the same distance from the burner at all times (Japanese Patent Application No. -22293, Japanese Patent Application No. 05-222
94). In this way, a plurality of ingots were synthesized. These ingots (φ160-500mm, L800-1200)
mm) to a disc-shaped test piece (φ150-450mm, t50mm) 50-1 to match the center of rotation of the ingot.
It was cut horizontally every 00 mm. For each sample, the measurement of striae under a high-pressure mercury lamp, the measurement of strain with a birefringence measuring device, and the refractive index distribution in the optical axis direction and the optical axis vertical direction by an oil-on-plate method using a He-Ne laser interferometer. The measurement was performed. Further, in order to measure the gradient component of the refractive index, a prism-shaped test piece was taken from the outside sandwiching the disc, and the absolute value of the refractive index was measured by the minimum deviation method. The upper layer of these cut bulk bodies
The sample was cut into a size of H30 × L150 × t10 mm, and the side surfaces were polished to obtain a hydrogen molecule concentration measurement sample piece. The rest is φ
60 × t10mm (with 5mm orientation flat)
The sample was cut into a size of 3 and polished on both sides and sides to obtain a hydrogen molecule concentration measurement, transmittance measurement, and excimer laser irradiation sample piece (see FIG. 6).

The hydrogen molecule concentration was measured by a laser Raman spectrophotometer. Quantification is based on the Raman scattered light in the direction perpendicular to the sample generated when Ar ⁺ laser (output 800 mW) is irradiated after setting the sample on the sample table.
measuring the intensity of cm ^-1 and 4135 cm ^-1, it was carried out by taking the intensity ratio (VSKhotimchenko et al., J.Appl.Spect
rosc., 46, 632-635 (1987)).

The transmittance was determined by measuring the internal transmittance of the sample at a thickness of 10 mm. The measurement was performed using a double-beam spectrophotometer for near red-visible-ultraviolet, and a thickness of 2
A mm sample was prepared by setting a 12 mm thick sample (both sampled from the same lot) on the measurement side. By doing so, multiple reflection components and surface reflection components in the sample are removed,
The internal transmittance at a thickness of 10 mm can be measured. At this time, in order to improve the accuracy of the spectrophotometer, the quartz glass standard samples (1 mm to 28 mm) with different thicknesses were adjusted so that the transmittance did not change due to the thickness at the measurement wavelength (Japanese Patent Application No. 5- 21121
7).

For the excimer laser irradiation, a KrF excimer laser (248 nm) and an ArF excimer laser (193 nm) were used for the irradiation sample piece, and the former was 1 × 10 ⁶ pulse at an energy density of 400 mJ / cm ² · pulse. Up to 1 × 10 ⁶ pulse with energy density of 100 mJ / cm ² · pulse for the latter. Samples prepared for measuring various physical properties are Samples 1 and 2 shown in Table 1.

As a result, in Sample 1, 4.1 × 10 ¹⁸ pieces / cm
^A very large number of ³ hydrogen molecules were dissolved in the quartz glass block. Even when the raw material was synthesized using trichlorosilane instead of silicon tetrachloride (Sample 2), 3.1 × 10 ¹⁸ hydrogen molecules / cm ³ were dissolved, although slightly reduced. In all of these samples, the refractive index distribution was center symmetric. Also, good results were obtained in the refractive index distribution both in the optical axis direction and in the direction perpendicular to the optical axis. Further, the transmittances at 248 nm and 193 nm were 99.9% or higher, and the transmittances after the excimer laser irradiation test were 99.9% or higher for both samples 1 and 2.

Comparative Example 1 Samples prepared here are Samples 3 to 6 in Table 1. Sample 3 is a hydrogen carrier, and the oxyhydrogen ratio in the outermost combustion gas is made to be more hydrogen excess than the oxyhydrogen ratio in the concentric multi-tube, sample 4 is an oxygen carrier, sample 5 is a helium carrier, and sample 6 is an argon carrier. It was synthesized by adjusting the oxyhydrogen ratio: 0.44 for the gas ejected from the gas discharge pipe. Sample 3 is about more than that of Example 1.
Although 1.7 times as many hydrogen molecules could be dissolved, the initial transmittance at 193 nm was poor due to the existence of an absorption band outside the vacuum ultraviolet region. In the excimer laser irradiation test, a decrease in transmittance was observed at the beginning, so the transmittance after excimer laser irradiation, especially A
Poor transmittance after irradiation at rF wavelength. Sample 4
Regarding, the initial value did not have an absorption band and the transmittance was good, but the hydrogen molecule concentration was as low as 3.5 × 10 ¹⁷ pieces / cm ³ . Further, although some deterioration was observed in Δn and RMS, a relatively good value was obtained. In the excimer laser irradiation test, the transmittance after irradiation was slightly decreased for both KrF and ArF wavelengths. In Samples 5 and 6, there was no absorption band at the initial stage and the initial transmittance was good, but the hydrogen molecule concentration was very low and was 1 × 10 ¹⁷ pieces / cm ³ or less. The transmittance of both samples after irradiation was very poor for both KrF and ArF.
Regarding Δn and RMS, although some deterioration was observed, relatively good values were obtained.

Example 2 A synthetic experiment was conducted by changing the burner shown in FIGS. 4 and 5 (Samples 7 and 8). The synthesis method is as shown in Table 2. As for the sample, the gas ratio of oxyhydrogen flowing out from the second and triple pipes was set to 0.293 (Sample 7), and the gas ratio of oxyhydrogen flowing out from the fourth and fifth pipes was changed.
It is 0.293 (Sample 8). Various physical properties were measured under the same conditions as in Example 1. In both samples, although the hydrogen molecule concentration was slightly lower than that of Sample 1, it was dissolved at 10 ¹⁸ pieces / cm ³ or more. The refractive index distributions of both Sample 7 and Sample 8 were also symmetrical.
Both samples have good Δn and RMS, and the initial transmittance and the transmittance after the excimer laser irradiation test are also Kr.
Both F and ArF maintained 99.9% or more.

[Comparative Example 2] The burner shown in FIGS. 4 and 5 is used.
A synthetic experiment was carried out using an oxygen carrier (Samples 9 and 1).
0). The physical properties of these samples are summarized below.
It was Ri. The refractive index distribution was also centrally symmetric
However, Δn and RMS are younger than Samples 7 and 8.
It was getting worse. Also, the hydrogen molecule concentration is 4.
3 x 10¹⁷Pieces / cm ³, Sample 10 below detection limit (<10¹⁶
Pieces / cm³) And much smaller than Samples 7 and 8
Was becoming. Initial transmittance was 99.9% or more in all cases
The measured values after the excimer laser irradiation test show that both KrF and ArF
Was observed. Also, the outermost combustion with hydrogen carrier
The oxyhydrogen ratio in gas is determined from the oxyhydrogen ratio of concentric multitubes.
For samples synthesized with excess hydrogen (Sample 11)
I made a measurement even when I was there. About this, the sump of Example 2
Melt about 1.6 or 2.7 times more hydrogen molecules than
However, there is also an absorption band outside the vacuum ultraviolet.
 The initial transmittance at 193 nm was poor. Excimer laser irradiation test
In the study, excimer
Transmittance after laser irradiation, especially the transmittance after irradiation at ArF wavelength.
The overkill was bad. Also, Δn and RMS deteriorate
There was a tendency.

Example 3 An ArF excimer laser was produced by using a quartz glass optical member obtained by processing the quartz glass of Sample 1 of Example 1 while maintaining the geometric center portion from the outer shape of an ingot. When a projection lens used as a light source was manufactured, it was confirmed that the desired design performance was satisfied. As a result, it was possible to obtain an integrated circuit pattern having a resolution of 0.3 μm or less and having practically sufficient flatness. Furthermore, it was confirmed that the optical performance was maintained for a long time without deterioration.

[0033]

As described above, the "proportion of oxygen gas and hydrogen gas ejected from a plurality of combustion ring-shaped pipes excluding the outermost portion" is defined as the theoretical equivalence ratio and "the outermost combustion ring-shaped pipe and its "Proportion of oxygen gas and hydrogen gas ejected from the internal combustion circular tube" is considered to be excessive hydrogen, or "oxygen gas and hydrogen gas ejected from multiple combustion ring-shaped tubes excluding the outermost portion""Proportion" is compared with the theoretical equivalence ratio to make hydrogen excess, and "Proportion of oxygen gas and hydrogen gas ejected from outermost combustion ring-shaped tube and internal combustion circular tube" is compared with the theoretical equivalence ratio. Equivalent or excess oxygen, more preferably by using a hydrogen carrier, high homogeneity and high UV transparency and UV resistance without secondary treatment which may cause contamination and cost increase. Can be obtained synthetic quartz glass with, it was possible to thereby obtain a large diameter quartz glass optical member.

[Brief description of drawings]

FIG. 1 is an example of the transmittance measurement results described in the examples.

FIG. 2 is an external view of a burner used in synthesizing quartz glass.

FIG. 3 is a view from the direction of the arrow in FIG. 2, and the numbers in the figure correspond to the numbers of gas types and flow rates in piping in Table 1.

FIG. 4 is an external view of a burner used in synthesizing quartz glass.

5 is a view from the direction of the arrow in FIG. 4, and the numbers in the figure correspond to the numbers of gas types and flow rates in the pipe in Table 2.

FIG. 6 is a flowchart when cutting a sample from a quartz ingot.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hydrogen gas or oxygen gas jet 2 ... Oxygen gas or hydrogen gas jet 5 ... Oxygen gas jet 6 ... Hydrogen gas jet 7 ... Carrier gas + raw material gas jet 11 ... Hydrogen gas or oxygen gas jet 12 ... Oxygen gas or hydrogen gas jet 13 ... Hydrogen gas or oxygen gas jet 14 ... Oxygen gas or hydrogen gas jet 15 ... Oxygen gas jet 16 ... Hydrogen gas jet 17 ... Carrier gas + source gas jet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Hiraiwa 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (12)

[Claims] 1. A circular tube for a raw material, which is arranged in the central part and which ejects a Si compound gas, and a plurality of ring-shaped tubes for combustion, which are arranged concentrically around this and ejects an oxygen gas and a hydrogen gas. With a burner having a plurality of combustion circular tubes arranged inside an external combustion ring tube to eject oxygen,
In the method for producing quartz glass in which a Si compound gas, oxygen gas, and hydrogen gas are jetted, and quartz glass powder is deposited on a target and vitrified to form an ingot, "a plurality of combustion ring-shaped tubes excluding the outermost portion""Proportion of oxygen gas and hydrogen gas ejected from" compared with the theoretical equivalence ratio and "proportion of oxygen gas and hydrogen gas ejected from the outermost combustion ring-shaped tube and the internal combustion circular tube" A method for producing quartz glass, which comprises making hydrogen excess. 2. A circular tube for a raw material, which is arranged in the central part and which ejects a Si compound gas, and a plurality of ring-shaped tubes for combustion, which are arranged concentrically around this and ejects an oxygen gas and a hydrogen gas. With a burner having a plurality of combustion circular tubes arranged inside an external combustion ring tube to eject oxygen,
In the method for producing quartz glass in which a Si compound gas, oxygen gas, and hydrogen gas are jetted, and quartz glass powder is deposited on a target and vitrified to form an ingot, "a plurality of combustion ring-shaped tubes excluding the outermost portion""Proportion of oxygen gas and hydrogen gas ejected from" is compared with the theoretical equivalence ratio to make hydrogen excess, and "of the oxygen gas and hydrogen gas ejected from the outermost combustion ring-shaped tube and the internal combustion circular tube" A method for producing quartz glass, characterized in that "proportion" is equal to or excess of oxygen as compared with the theoretical equivalent ratio. 3. The quartz glass according to claim 1 or 2, wherein hydrogen gas is used as a carrier gas when the Si compound gas is ejected from the raw material circular tube. Manufacturing method. 4. The quartz glass manufactured by the method for manufacturing quartz glass according to claim 1 or 2, wherein the RMS value of the wavefront aberration is 0.02λ or less after correction of the power component. 5. The quartz glass produced by the method for producing quartz glass according to claim 1 or 2, wherein the homogeneity of the refractive index in one direction is Δn ≦ 2 × 1 without power component correction.
Quartz glass characterized in that it is 0 ^-6 . 6. A quartz glass member using the quartz glass according to claim 5, wherein the one direction is an optical axis direction. 7. The quartz glass produced by the method for producing quartz glass according to claim 1 or 2, characterized in that the extremum of the refractive index distribution in a cross section in one direction is one and is centrally symmetric. Quartz glass. 8. A quartz glass member using the quartz glass according to claim 7, wherein the cross section in the one direction is a cross section including an incident optical axis. 9. A quartz glass produced by the method for producing quartz glass according to claim 1 or 2, wherein the amount of 365n
Quartz glass with an internal transmittance of more than 99.9% at 10 mm at m, 248 nm, and 193 nm. 10. A quartz glass produced by the method for producing quartz glass according to claim 1 or 2, wherein Kr is
A quartz glass characterized by having an internal transmittance of 10 mm at 248 nm of more than 99.9% after being irradiated with 10 ⁶ pulses of F excimer laser at 400 mJ / cm ² · pulse. 11. A quartz glass produced by the method for producing quartz glass according to claim 1 or 2, wherein Ar is Ar.
A quartz glass characterized by having an internal transmittance of 10 mm at 193 nm of more than 99.9% after irradiation with F 6 excimer laser at 100 mJ / cm 2 · pulse for 10 ⁶ pulses. 12. The quartz glass produced by the method for producing quartz glass according to claim 1 or 2, wherein the hydrogen concentration is 5 × 10 ¹⁷ pieces / cm ³ or more, and the central portion is higher than the peripheral portion. Quartz glass characterized by having a hydrogen concentration.