JP2000239040A - Quartz glass material for optical member for f2 excimer laser, and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material having a high light transmittance at an oscillation wavelength of an F2 excimer laser by respectively specifying the OH group concentration, F concentration and H concentration. SOLUTION: This material is obtained by regulating the OH group concentration to <=5 ppm, the F concentration to 0.1-2 mol% and the H concentration to <=5×1016 molecules/cm3. The material is further excellent in laser resistance to irradiation with an F2 excimer laser. The material preferably has >=70% internal transmittance at 157 nm which is the F2 excimer laser oscillation wavelength and/or >=90% internal transmittance at 163 nm and/or <=5% lowering of transmittance at 157 nm wavelength based on 10 mm after irradiation of 3×105 pulses of the F2 excimer laser at 10 mJ/cm2 energy density per pulse and/or <=2×10-5 difference n between the maximum value and the minimum value of the refractive index and/or <=0.5 nm/cm amount of refractive index when making measurement at 633 nm wavelength. Thereby, the resultant material is useful for a lens a window, etc., for transmitting the F2 excimer laser.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lens, window, filter, beam splitter, to F ₂ excimer laser optical member for the synthetic quartz glass material and an optical member that can be used in F ₂ excimer laser, such as a photomask.

[0002]

2. Description of the Related Art Conventionally, an optical lithography technique for transferring a pattern on a mask onto a wafer using light is superior in cost as compared with other techniques using electron beams or X-rays. Is widely used as an exposure apparatus for manufacturing a semiconductor device.

In recent years, with the miniaturization and integration of LSIs, the wavelength of light as a light source has been shortened. Conventionally, a wavelength of 3 to 4 μm, which can form a pattern with a line width of 0.5 to 0.4 μm, has been used.
An exposure apparatus using a KrF excimer laser having a wavelength of 248 nm, which can form a 65 nm i-line or a pattern having a line width of 0.25 to 0.35 μm, has been practically used. Recently, an exposure apparatus using an ArF excimer laser having a wavelength of 193 nm, which can form a pattern having a line width of 0.13 to 0.20 μm, has also been developed.

Further, next-generation lithography techniques of ArF include electron beam direct writing technique, X-ray equal magnification exposure technique,
₂ has been considered excimer laser exposure technique or the like, an electron beam direct描技procedure in this in its throughput, the X-ray magnification exposure technique have critical challenges mask making, F ₂ laser exposure technique ArF exposure Because of the extension of the technology, it is receiving the most attention as the next-generation exposure technology.

As conventional optical materials for excimer lasers such as KrF and ArF, quartz glass, particularly high-purity synthetic quartz glass, is used from the viewpoints of transmittance, laser resistance, homogeneity and the like. In the wavelength range of KrF and ArF, quartz glass shows high light transmittance, laser resistance is improved by optimizing the manufacturing conditions, and optical materials for excimer lasers, particularly those usable as projection lenses, are obtained. I have.

However, as an optical material for an F ₂ excimer laser, its oscillation wavelength is 157 nm and ArF
Therefore, the conventional synthetic quartz glass for KrF and ArF could not be used because a sufficient transmittance was not obtained. For this reason, the only optical material that can be used is fluorite, which has been a major constraint on device design.

On the other hand, it is known that the transmittance of 157 nm of quartz glass can be greatly improved by doping fluorine glass into quartz glass. JP-A-4-
No. 195101 discloses a method in which quartz glass is doped with fluorine to reduce or eliminate defect absorption in a wavelength range of 155 to 400 nm and to prevent defects even when irradiated with high-energy ultraviolet rays for a long period of time. I have.

Japanese Patent Application Laid-Open No. Hei 8-67530 discloses that quartz glass contains 1 mol% or more of fluorine and an OH group concentration of 10 pp.
Although by doping or m of improving the stability against ArF excimer laser technology has been disclosed, the same publication at the same time F ₂ excimer laser wavelength region 15
It is shown that the ultraviolet transmittance around 7 nm is greatly improved.

[0009]

[SUMMARY OF THE INVENTION Indeed, although the optical stability against ArF excimer laser by fluorine is contained in the quartz glass increases, and the F ₂ excimer laser of shorter wavelength ultraviolet laser irradiation In this case, it was found that the generation of defects alone was not sufficiently suppressed by the irradiation of the excimer laser.

[0010] The inventors of the present invention, the ultraviolet rays to be particularly irradiated when the F ₂ excimer laser, F ₂ excimer laser properties of quartz glass during the irradiation and damage behavior results of studying, as a silica glass for F ₂ excimer laser The present inventors have found suitable glass properties and have led to the present invention.

[0011] Namely, the present invention is that the light transmittance at an oscillation wavelength of F ₂ excimer laser 157nm high withstand laser resistance against F ₂ excimer laser irradiation to provide a high F ₂ excimer laser for optical quartz glass With the goal.

[0012]

The present invention relates to an optical quartz glass for an F ₂ excimer laser, which has an OH group concentration of 5p.
pm or less, contains fluorine of 0.1 to 2 mol%, and has a hydrogen concentration of 5 × 10 ¹⁶ molecules / cm ³ or less.

In quartz glass, oxygen-excess type defects such as peroxylinkage (Si--O--O--Si) and dissolved oxygen molecules, and oxygen deficiency defects such as Si--Si bonds and oxygen vacancies (Si... Si ), Other OH groups, H ₂ O, etc.
Due to these effects, the transmittance decreases in the short wavelength region of 157 nm, which is the oscillation wavelength of the F ₂ excimer laser,
By doping with fluorine, by terminating structural defects in quartz glass, the stability to high-energy ultraviolet lasers such as ArF excimer lasers is improved,
The transmittance at 157 nm is improved.

However, even in such a quartz glass, an E 'center (e-prime center) is induced by the irradiation of the F ₂ excimer laser, and the light absorption due to the generation of the E' center affects even the ultraviolet absorption edge.
It has been confirmed that this also causes a decrease in the light transmittance in nm and a decrease in the laser resistance to F ₂ excimer laser irradiation. In order to suppress the formation of the E ′ center, 7.6 eV (1
It has been found that it is necessary to sufficiently reduce oxygen deficiency defects having an absorption at 63 nm).

The present invention is a result of examining the influence of a wide range of fluorine concentration, and shows that the fluorine content is 0.1 m
Characteristically, it is set to ol% to 2 mol%. When the amount of fluorine to be contained is less than 0.1 mol%, the effects thereof are not sufficient, and when the amount is more than 2 mol%, oxygen deficiency defects are easily induced.
% Is preferred, from 0.7 mol% to 1.5 mol%
Is particularly desirable.

It should be noted that the display of the fluorine concentration may be made by those skilled in the art.
The relationship is expressed in two ways, ol% and weight%, and these relationships are given by the following formulas and can be compared with each other. MOL% = 0.32 x weight%

On the other hand, OH groups have conventionally been considered to increase the stability to an ArF excimer laser. However, if an OH group exceeding the limit is present, NBOHC (Non-Bridged Oxygen Hole Center) is irradiated by F ₂ excimer laser irradiation.
Is generated, which is considered to be a cause of defect generation by F ₂ excimer laser irradiation.

Therefore, a further feature of the present invention is that the limit of the OH group concentration is set to 5 ppm or less. When an F ₂ excimer laser is actually irradiated on quartz glass containing 10 ppm or more of OH groups, the generation of the E ′ center at the 215 nm absorption peak and the intense 260 nm absorption peak N
The formation of BOHC was confirmed. At the same time, 3
Infrared absorption peak at 680 cm ^-1 is shifted to about 26cm ^-1 wave number side lower, the peak intensity was decreased by about 6%.

This is a phenomenon that has not been observed in the conventional KrF and ArF irradiations.
V), which was hardly affected by the energy of about ArF (6.4 eV), but the high-energy line of F ₂ (7.9 eV) affected the O—H bond of Si—OH, It is considered that NBOHC was generated.
Therefore, the OH group concentration is 5 ppm or less, preferably 1 pp.
m or less is good.

According to the present invention, as described above, the hydrogen concentration in the quartz glass material and the optical member of the present invention is 5 × 10 ¹⁶ molecules / cm ³ or less. It is generally known that hydrogen molecules improve the excimer laser durability of quartz glass. Patent No. 2134624, Patent 18980
No. 31 and Japanese Patent No. 2140768 disclose KrF by adding hydrogen to quartz glass in an amount of 5 × 10 ¹⁶ molecules / cm ³ or more.
Excimer laser, to a technology of improving the durability is indicated for ArF excimer laser, JP-A-8-75901 with respect to _{F 2} excimer laser, JP-A-1
No. 0-6521, fluorine and hydrogen molecules are also contained in quartz glass in the same manner, whereby F ₂
There is a statement that the durability to the steel has been improved. However, the inventors have found that the OH group is 5 ppm or less and the F concentration is 0.1 to 2 ppm.
In the quartz glass in the range of mol%, hydrogen molecules have rather found to decrease the durability to the F ₂ excimer laser, leading to the present invention.

As an effective means of the present invention, the present invention is characterized in that the internal transmittance at 157 nm, which is the oscillation wavelength of the F ₂ excimer laser, is at least 70%.

It is necessary to appropriately suppress the fluorine concentration, the OH group concentration, and the oxygen deficiency defect, and to obtain a metal impurity having an effect of shifting the absorption edge to the longer wavelength side as much as possible. Can be. In order to achieve such transmittance, Cu, Ni, Ti, C are used as transition metals.
The total of r and Fe is 30 ppb or less, the total amount of alkali metal is 50 ppb or less, and the total amount of alkaline earth metal impurities is 80 ppb.
It is necessary to reduce it to ppb or less.

Further, if oxygen gas and ozone gas are present in silica, the absorption in the ultraviolet region is caused by the influence of the dissolved gas, which shifts the absorption edge to the longer wavelength side and at the same time is an important cause of NBOHC generation. Becomes Therefore, the transmittance at 157 nm is itself an important measure for the stability to the laser, and it is necessary that the internal transmittance is 70% or more, preferably 80% or more.

Further, as an effective means of the present invention, 16
The internal transmittance at 3 nm is set to 90% or more. Oxygen-deficient defects easily form an E 'center even at 163 nm by excimer laser irradiation, but as shown in Table 1, there is no substantial problem if the internal transmittance at this wavelength is 90% or more. all right.

Further, as an effective means of the present invention, an F ₂ excimer laser is irradiated with an energy density of 10 m per pulse.
It is characterized in that the transmittance at a wavelength of 157 nm after irradiation of 3 × 10 ⁵ pulses at J / cm ² is 5% or less per 10 mm.

In order to ensure practical stability as an optical material, the optical quartz glass for transmitting an F ₂ excimer laser according to the present invention is obtained by applying an F ₂ excimer laser at an energy density of 10 mJ / cm ² to 3 × 10 ⁵ pulses. Wavelength 157 after irradiation
It is necessary that the transmittance decrease in nm is 5% or less per 10 mm in thickness. This corresponds to a decrease in transmittance between 3 × 10 ⁷ pulses and 3 × 10 ⁹ pulses, assuming that the transmitted energy in actual use is 0.1 mJ / cm ^2. This is to ensure satisfactory durability.

Furthermore, the present invention relates to the difference Δ between the minimum value and the maximum value in the uniformity of the refractive index distribution in the quartz glass material of the present invention or in the optical member produced therefrom.
n is 2 × 10 ⁻⁵ or less. Since this is an optical member suitable for the intended use of the present invention, it is a preferable requirement to provide it.

It is also an effective means of the present invention that the birefringence when measured at a wavelength of 633 nm is 0.5 nm / cm or less. Precise birefringence measurement is performed using He / Ne
The retardation (Δnd), which is the difference in the optical path of polarized light due to birefringence, is measured using an ellipsometer or the like using a laser (wavelength 633 nm). The amount of refraction is calculated as 2 nm / cm by dividing retardation by thickness.

In such a case, the retardation of 10 nm is 10/63 based on the relationship with the measurement wavelength of 633 nm.
3 = 0.0158λ, and when the wavelength used is 157 nm, the value is 0.063λ, which is four times or more, which is a range in which a problem occurs. Also, because the photoelastic constant has wavelength dependence,
A light having a birefringence amount of 157 nm measured at 633 nm gives a larger birefringence. In this sense, the optical material for an F ₂ excimer laser has a birefringence at a wavelength of 633 nm of 0.5 nm / c which is 1/4 of the conventional value.
It is important that it is less than m.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

The F content in the quartz glass described in the following comparative examples and examples is measured by Lazer-Raman spectroscopy. (J. Material Sci. 28 (1993) 2738-2744) The internal transmittance T referred to in the present invention refers to the internal transmittance per 10 mm thickness, the apparent transmittance D and the theoretical transmittance of a sample per 10 mm thickness. It is calculated using T0. That is, assuming that R is the reflectance and n is the refractive index, R = (n−1) ² / (n + 1) ² (1) T ₀ = (1-R) ² (2) T = D / T ₀ (3)

Since the refractive index of the quartz glass containing F changes depending on the F concentration, it is necessary to measure the refractive index each time when calculating the internal transmittance. However, the accurate measurement of the refractive index in the 157 nm region is required. Is very difficult. Therefore, in the present invention, the refractive index of quartz glass having an F concentration in the range of 0.1 mol% to 2.0 mol% is 1.689, respectively.
７７1.677, and the internal transmittance was calculated using this. Actually, a sample having a thickness of 10 mm is polished very precisely, and the apparent transmittance may be 61.1% or more, preferably 69.8% or more.

Further, birefringence is an important factor for use as an optical member for the purpose of the present invention. Generally, precise birefringence measurement is performed using a He / Ne laser (wavelength 633 n).
The retardation (Δnd) is measured using an ellipsometer or the like using m). Then, the birefringence amount S is calculated as S = (Δnd) / thickness of the sample (4). Retardation (Δnd) is the optical path difference of polarized light due to birefringence. When a sample having a thickness of 5 cm is measured to have a retardation of 10 nm, the birefringence S is calculated as 2 nm / cm by dividing the retardation by the thickness. Is done.

In such a case, the retardation of 10 nm is 10/63 based on the relationship with the measurement wavelength of 633 nm.
3 = 0.0158λ, which is an amount that does not cause a problem optically, but is 0.0 if the wavelength used is 157 nm.
63λ, which is four times or more, which is a range in which a problem occurs. In addition, since the photoelastic constant has wavelength dependency, a larger birefringence may be given to light having a birefringence amount of 157 nm measured at 633 nm, and the problem becomes serious. In this sense, the optical material for an F ₂ excimer laser has a birefringence at a wavelength of 633 nm of 0.5 n, which is 1/4 of the conventional value.
It is important that it is not more than m / cm. In order to achieve such a low birefringence, the annealing point (1
The cooling rate from 150 ° C) is set to 5 ° C / hour or less,
In addition, it is necessary to set the end point temperature of the slow cooling to 600 ° C. or less.

Example 1 Silica fine particles produced by hydrolyzing high-purity SiCl ₄ with oxyhydrogen flame were deposited on a rotating substrate to form a white opaque soot body. The weight of the obtained soot body was 2 kg, and the bulk density was 0.25 g / cm ³
Met. After treating it in an electric furnace for 1000 × 5 hours in a mixed atmosphere of chlorine and oxygen (mixing volume ratio Cl ₂ / O ₂ = 20/80), SiF ₄ and He (mixing volume ratio Si
F ₄ / He = 5/95) at 1100 ° C.
Heat treatment was performed for 15 hours, and then the atmosphere of He gas at 1 atm was set to a maximum temperature of 1460 ° C., and the inside of the furnace was slowly pulled up to form a transparent glass to produce a quartz glass ingot.

Further, the quartz glass ingot was annealed in an electric furnace. Annealing is performed at 1150 ° C on a quartz glass disk cut from a quartz glass ingot.
And cooled slowly to 550 ° C. at a cooling rate of 1 ° C./hour. In addition, the atmosphere was set to an atmospheric pressure atmosphere of nitrogen in order to prevent mixing of oxygen during annealing, and the chamber was placed in a synthetic quartz chamber in order to prevent mixing of metal impurities. Since a chamber made of this synthetic quartz glass often contains hydrogen molecules, it is necessary to prevent the diffusion of hydrogen molecules from the chamber during annealing at a temperature of 800 ° C. or more prior to annealing.
An air baking was performed for about an hour, and a hydrogen molecule contained in the chamber was diffused to the outside to use. The apparent transmittance D with respect to the wavelength λ of the obtained quartz glass before and after irradiation with the F ₂ laser was measured, and the relationship was plotted as shown in FIGS. 1 and 3 with the apparent transmittance D as the vertical axis and the wavelength λ as the horizontal axis. . Further, the absorbance is plotted on the vertical axis and the light energy (eV) is plotted on the horizontal axis, and the relationship is plotted as shown in FIG.

The F ₂ excimer laser irradiation was performed at 3.5 × 10 3 at an energy density of 8 mJ / cm 2 per pulse.
^Five shots were performed at a repetition frequency of 400 Hz by replacing the optical path with nitrogen. Furthermore, the transmittance measurement of the sample is φ30m
Both surfaces of the mx10 mm sample were finished by high-precision optical polishing (surface roughness RMS is 3 A or less), and the inside of the measurement chamber was evacuated using a vacuum ultraviolet spectrophotometer manufactured by JASCO.

Using the above equations (3) and (4), the internal transmittance of the obtained quartz glass at 163 nm, F
₂ Internal transmittance of 157 nm before and after laser irradiation, 63
Table 1 shows data on the birefringence S measured at 3 nm, the OH group content, and the F content measured by laser Raman spectroscopy. Further, Table 3 shows data on the H2 content measured by laser Raman spectroscopy.

[0039]

[Table 1]

[Embodiment 2] SiF during heat treatment of Embodiment 1
₄ and He (mixing volume ratio SiF ₄ / He = 1 /
A quartz glass ingot was manufactured under the same conditions except that the method was changed to 99), and a quartz glass disk cut from the quartz glass ingot was heat-treated. And the above (3)
Using the formula and the formula (4), 163n
m internal transmittance, 157 nm before and after F ₂ laser irradiation
Internal transmittance, birefringence S, OH measured at 633 nm
Table 1 shows data on the group content and the F content.

[Comparative Example 1] High-purity SiCl ₄ was hydrolyzed by oxyhydrogen flame to form a white opaque soot body, which was then placed in an electric furnace at 1,000 × 5 hours for chlorine and oxygen (mixing volume ratio Cl ₂ / After the treatment in a mixed atmosphere of (O ₂ = 20/80), the temperature was raised and the heat treatment was performed at 1100 ° C. × 15 hours. It was vitrified to produce a quartz glass ingot. The apparent transmittance D with respect to the wavelength λ of the obtained quartz glass before and after irradiation with the F ₂ laser was measured, and the relationship was plotted as shown in FIG. 1 with the apparent transmittance D as the vertical axis and the wavelength λ as the horizontal axis. Further, the absorbance is plotted on the vertical axis and the light energy (eV) is plotted on the horizontal axis, and the relationship is plotted as shown in FIG. Then, using the above formulas (3) and (4), the obtained quartz glass has an internal transmittance of 163 nm, an internal transmittance of 157 nm before and after F ₂ laser irradiation, and a birefringence S, OH measured at 633 nm. Table 1 shows data on the group content and the F content.

Comparative Example 2 High purity SiCl ₄ was hydrolyzed by oxyhydrogen flame to form a white opaque soot body, which was transparently vitrified at 1480 ° C. in a vacuum atmosphere in an electric furnace to produce a quartz glass ingot. did. The apparent transmittance D with respect to the wavelength λ of the obtained quartz glass before and after irradiation with the F ₂ laser was measured, and the relationship was plotted as shown in FIG. 1 with the apparent transmittance D as the vertical axis and the wavelength λ as the horizontal axis. Further, the absorbance is plotted on the ordinate and the light energy (eV) is plotted on the abscissa, and the relationship is plotted as shown in FIG. Then, using the above equations (3) and (4), the obtained quartz glass was 163 nm thick.
Table 1 shows data on the internal transmittance of the sample, the internal transmittance at 157 nm before and after F ₂ laser irradiation, the birefringence S measured at 633 nm, the OH group content, and the F content.

Comparative Example 3 The quartz glass body obtained in Example 1 was used in an electric furnace having a furnace material made of alumina having a purity of 96% without using a synthetic quartz glass chamber. Annealing was performed under the same conditions. And
Using the above formulas (3) and (4), the obtained quartz glass has an internal transmittance of 163 nm, an internal transmittance of 157 nm before and after irradiation with F ₂ laser, a birefringence S measured at 633 nm, and an OH group content. Table 1 shows the data on the amount and the F content.

Comparative Example 4 A quartz glass disk cut from the quartz glass ingot obtained in Example 1 was placed in a quartz glass chamber in an electric furnace and annealed in the same manner as in Example 1. Annealing is performed in an atmosphere of nitrogen 11
After holding at 50 ° C. for 20 hours, the cooling rate was 1 ° C./hour for 5 hours.
While maintaining the temperature at 50 ° C., a 1: 1 mixed gas of nitrogen and hydrogen was introduced, and heat treatment was performed for 20 hours. After the heat treatment, the power supply to the furnace was stopped, and the furnace was naturally cooled.

The apparent transmittance D with respect to the wavelength λ of the obtained quartz glass before and after irradiation with the F ₂ laser was measured, and the relationship was plotted as shown in FIG. 3 with the apparent transmittance D as the vertical axis and the wavelength λ as the horizontal axis. .

Using the above equations (3) and (4), the internal transmittance of the obtained quartz glass at 163 nm, F
₂ Internal transmittance of 157 nm before and after laser irradiation, 63
Table 3 shows data on the hydrogen molecule content measured at 3 nm and the F content.

Table 2 shows the ICP of Example 1 and Comparative Example 3.
The analysis result of the quartz glass by the mass spectrum method is shown.
The sum of the five metals in the table is Cu, Ni, Ti, Cr, F
The sum of e.

[0048]

[Table 2]

[0049]

[Table 3]

From the above data, it can be seen that the apparent transmittance does not decrease in Example 1 after irradiation with the F ₂ excimer laser, but the apparent transmittance greatly decreases in Comparative Examples 1 and 2. When the OH group concentration is 1 ppm or less and the fluorine concentration is 1.0 mol%, the internal transmittance at a wavelength of 163 nm is 92%, and the wavelength is 157 nm before and after laser irradiation.
Has a high internal transmittance of 89%, and has a birefringence of 0.5 nm / cm or less when measured at a wavelength of 633 nm, which is 1/4 or less of the conventional value.

[0051]

According to the present invention, the OH group concentration in quartz glass is 5 ppm or less and the fluorine concentration is 0.1 to 2 mol.
By defining the internal transmittance at 157 nm to be 70% or more, the oscillation wavelength of the F ₂ excimer laser is 15%.
An optical quartz glass for F ₂ excimer laser transmission having high light transmittance at 7 nm and high laser resistance to F ₂ excimer laser irradiation is provided.

[Brief description of the drawings]

FIG. 1 is a vacuum ultraviolet spectrum chart of samples of Example 1 and Comparative Examples 1 and ₂ before and after irradiation with an F ₂ excimer laser.

FIG. 2 shows absorption bands (difference spectrum) of vacuum ultraviolet light of the samples of Example 1 and Comparative Examples 1 and ₂ before and after irradiation with F ₂ excimer laser.

FIG. 3 is a vacuum ultraviolet spectrum chart of the samples of Example 1 and Comparative Example 4 after irradiation with an F ₂ excimer laser.

[Explanation of symbols]

 T Internal transmittance D Apparent transmittance R Reflectivity n Refractive index λ Wavelength

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 18, 2000 (2000.1.1)
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2 is an absorption band (difference spectrum) in vacuum ultraviolet of the samples of Example 1 and Comparative Examples 1 and ₂ after irradiation with an F ₂ excimer laser.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3 is a vacuum ultraviolet spectrum chart of samples of Example 1 and Comparative Example 4 before and after irradiation with an F ₂ excimer laser.

Continued on the front page (72) Inventor: Akira Fujinoki 88, Kawakubo, Kanaya, Tamura-cho, Koriyama, Fukushima Prefecture Inside the Quartz Research Laboratory, Shin-Etsu Quartz Co., Ltd. (72) Hiroyuki Nishimura 88, Kawakubo, Kanaya, Tamura-cho, Koriyama, Fukushima Inside Quartz Research Institute, Inc. (72) Inventor Hideo Hosono 2784-2-212, Shimotsuruma, Yamato City, Kanagawa Prefecture (72) Inventor Toru Ogawa 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture

Claims (6)

[Claims] 1. An OH group concentration of 5 ppm or less, a fluorine concentration of 0.1 to 2 mol%, and a hydrogen concentration of 5 × 10 ¹⁶ molecules /
A synthetic quartz glass material and an optical member for an F ₂ excimer laser optical member, wherein the diameter is not more than cm ³ . 2. An F ₂ excimer laser oscillation wavelength of 1
The synthetic quartz glass material and optical member for an F ₂ excimer laser optical member according to claim 1, wherein the internal transmittance at 57 nm is 70% or more. 3. The internal transmittance at 163 nm is 90%.
The F _{2 according} to claim 1 or _{2, wherein}
Synthetic quartz glass material and optical member for excimer laser optical member. 4. The method according to claim 1, wherein a decrease in transmittance at a wavelength of 157 nm after irradiation of an F ₂ excimer laser at an energy density of 10 mJ / cm ² per pulse of 3 × 10 ⁵ pulses is 5% or less per 10 mm. 4. A synthetic quartz glass material and an optical member for an F ₂ excimer laser optical member according to any one of items 3 to 3. 5. The difference Δn between the maximum value and the minimum value of the refractive index is 2 ×
The synthetic quartz glass material and optical member for an F ₂ excimer laser optical member according to claim 1, wherein the optical member is 10 ⁻⁵ or less. 6. The synthetic quartz glass material for an F ₂ excimer laser optical member according to claim 1, wherein a birefringence when measured at a wavelength of 633 nm is 0.5 nm / cm or less. Optical members.