JP2003192429A - Low thermal expansion ceramic material and parts and mirror for manufacturing device for semiconductor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic material which is to be used as parts for manufacturing semiconductors, the parts to be disposed in an exposure device using extreme UV projection exposure techniques (EUVL) and to accept high heat quantity for the exposure process, and which hardly causes thermal deformation and which shows high heat conduction by radiation. <P>SOLUTION: The low thermal expansion ceramic material has 1×10<SP>-6</SP>/°C coefficient of thermal expansion at 0 to 20°C and ≥80% average emissivity at 3.33 to 25.42 μm wavelengths. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reticle (mask) in an exposure apparatus using extreme ultraviolet exposure technology (EUVL), a wafer stage position measuring mirror or the like, or a supporting member thereof, a wafer in a film forming apparatus or an etching apparatus. The present invention relates to a low thermal expansion ceramics used for a susceptor or a vacuum chuck for holding, a jig for various semiconductor manufacturing processes, a structural member for a vacuum device, and the like, and a semiconductor manufacturing device component using the low thermal expansion ceramics.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has improved, there has been a growing demand to increase the accuracy of exposure and transfer of circuit patterns. As a technology to meet this demand, ultra-short wavelength ultraviolet rays having a high energy level ( Wavelength 13n
m) and X-ray (wavelength 0.1 to 10 nm) extreme ultraviolet projection exposure technology (EUVL) has come to be used. FIG. 1 shows a schematic configuration of an extreme ultraviolet reduction projection exposure apparatus using the extreme ultraviolet projection exposure technology (EUVL).

In FIG. 1, reference numeral 1 denotes an illumination optical system, which is arranged at a predetermined position in a chamber 8 and collects extreme ultraviolet rays emitted from a light source and then holds it on a reticle stage 3 to provide an exposure pattern. A beam having a predetermined size is formed on the surface of the reticle 2. The extreme ultraviolet light emitted from the reticle 2 is reduced by the reduction optical system 4 in which the mirrors 4a and 4b are combined.
Through, it is reduced and coupled onto the surface of the wafer 5 held on the wafer stage 6. A wafer stage position measuring mirror 7 mounted on the wafer stage 6 and having a mirror surface measures the positioning of the wafer stage 6 (Japanese Patent Laid-Open No. 7-263322, "Optical system for extreme ultraviolet lithography". Development and Evaluation "(Oplus E2
(May 000))). When the wafer 5 is irradiated with extreme ultraviolet rays in the high vacuum to low vacuum region where the degree of vacuum in the chamber 8 exceeds 10 ⁻⁵ Pa when performing the exposure process, the extreme ultraviolet rays are significantly attenuated by the air on the optical path. The degree of vacuum in the chamber 8 must be maintained at an ultrahigh vacuum of at least 10 ⁻⁵ Pa or less. When extreme ultraviolet rays are irradiated in such an ultra-high vacuum, the reticle 2, reticle stage 3,
Heat is generated in the semiconductor manufacturing equipment components such as the mirrors 4a and 4b, the wafer stage 6, the wafer stage position measuring mirror 7, etc. However, since there is no escape area for heat in the ultra-high vacuum, the temperature rises significantly, The exposure transfer accuracy will be reduced.

Conventionally, alumina-based ceramics and silicon nitride-based ceramics have been widely used as ceramics used for the above-mentioned parts for semiconductor manufacturing equipment because they are relatively inexpensive and chemically stable.

Recently, it has been proposed to apply low thermal expansion ceramics such as cordierite and high-purity quartz as parts for semiconductor manufacturing equipment (Japanese Patent Laid-Open No. 8-1).
No. 43329, JP-A No. 11-209171,
See JP-A-2000-247732). JP-A-8-14
In 3329 gazette, it is proposed to use high-purity quartz as a constituent material of a flange, a jig, a heat insulating fin, a core tube, a soaking tube and the like used in semiconductor manufacturing.

Further, in Japanese Patent Laid-Open Nos. 11-209171 and 2000-247732, cordierite ceramics are used as a structural member for a vacuum device, a susceptor, a vacuum chuck, a stage in an exposure device, or a wafer stage position measuring mirror. It has been proposed to use it as a member for a semiconductor manufacturing device and the like.

[0007]

However, although alumina ceramics and silicon nitride ceramics which have been generally used as parts for semiconductor manufacturing equipment have a smaller coefficient of thermal expansion than metals, they have a thermal expansion coefficient of 0 to 20 ° C. Coefficients are about 5.0 × 10 ^-6 / ° C and about 1.5 × 1 respectively
When the ambient temperature changes by 0 ° ^C./0.1° C., for example, a wafer stage having a side length of about 0.5 m will be deformed by several μm. In the required process, there is a problem that the productivity of the semiconductor is reduced due to this deformation.

On the other hand, although quartz is a material whose coefficient of thermal expansion at 0 to 20 ° C. is 0.45 × 10 ⁻⁶ / ° C., which is smaller than that of alumina ceramics and silicon nitride ceramics, quartz has wavelengths of 3.33 to 25. Since the average emissivity at 42 nm is as small as 67%, there is a problem that heat is difficult to escape when quartz is used as a component for a semiconductor manufacturing device of an exposure apparatus using the extreme ultraviolet exposure technology (EUVL).

The cordierite-based ceramics proposed in JP-A-11-209171 and JP-A-2000-247732 have a low coefficient of thermal expansion, even though they have a coefficient of thermal expansion of 1 × 10 ⁻⁶ / ° C. or less. It was not one that had both great radiation characteristics at the same time. Therefore, an object of the present invention is to provide a ceramic having a low thermal expansion characteristic and a large emissivity. Another object of the present invention is to provide a member for semiconductor manufacturing equipment using the above ceramics.

[0010]

Therefore, the low thermal expansion ceramics of the present invention has a thermal expansion coefficient of 1 at 0 to 20 ° C.
× 10 ⁻⁶ / ° C. or less and a wavelength of 3.33 to 25.42
The average emissivity in μm is 80% or more.

Further, the thermal expansion ceramics of the present invention are characterized in that the thermal conductivity at room temperature is 3 W / m · k or more.

The low thermal expansion ceramics of the present invention is
The average emissivity at a wavelength of 3.33 to 25.42 μm is 9
The rare earth oxide powder is added and mixed in a proportion of 1 to 20% by weight with respect to the cordierite powder of 4% or more and the mixed powder obtained is molded by a desired molding means, and then the temperature is set to 110.
It is characterized by being obtained by firing at 0 to 1450 ° C.

Further, the parts for semiconductor manufacturing equipment of the present invention are
It is characterized by being formed from the low thermal expansion ceramics.

Further, the mirror of the present invention is a mirror using the above low thermal expansion ceramics and is characterized by being used in a vacuum.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 denotes an illumination optical system, which is arranged at a predetermined position in a chamber 8 and collects extreme ultraviolet rays emitted from a light source, and then is held on a reticle stage 3 to have an exposure pattern. A beam having a predetermined size is formed on the surface of the reticle 2. The extreme ultraviolet light emitted from the reticle 2 is reduced by the reduction optical system 4 in which the mirrors 4a and 4b are combined.
Through, it is reduced and coupled onto the surface of the wafer 5 held on the wafer stage 6. A wafer stage position measuring mirror 7 mounted on the wafer stage 6 and having a mirror surface is for measuring the positioning of the stage 6. During the exposure process, the vacuum degree in the chamber 8 is 10 ⁻⁵ P.
It is maintained in an ultrahigh vacuum of a or less.

The low thermal expansion ceramics of the present invention are 0 to 2
Coefficient of thermal expansion at 0 ° C is 1 × 10 ^-6Below / ℃
The wavelength of 3.33, which is part of the wavelength range of the far infrared rays
The average emissivity at 25.42 μm is 80% or more
Is important, reticle 2, reticle stage 3,
Mirrors 4a, 4b, wafer stage 6, wafer stage
For use as parts for semiconductor manufacturing equipment such as position measurement mirror 7
Is preferred.

Here, 0 to 0 of the above low thermal expansion ceramics is used.
The coefficient of thermal expansion at 20 ° C. is set to 1 × 10 ⁻⁶ / ° C. or less, because when the coefficient of thermal expansion exceeds 1 × 10 ⁻⁶ / ° C., dimensional change due to temperature change becomes large, so This is because when it is used for a component, the exposure transfer accuracy is lowered during the exposure process.

Further, the average emissivity at the wavelength of 3.33 to 25.42 μm is set to 80% or more. When the average emissivity is less than 80%, when it is used for the above-mentioned semiconductor manufacturing device parts, the exposure apparatus is used. This is because the atmosphere inside is a vacuum, so that the heat conduction due to the radiation of these semiconductor manufacturing device components cannot be increased and the temperature rise cannot be suppressed.

Here, the average emissivity at a wavelength of 3.33 to 25.42 μm means a wavelength of 3.33 to 25.42 μm.
Is the average value of the integrated emissivity in, and can be measured using a far infrared spectroradiometer. Also, the wavelength 3.33
The wavelength range of ˜25.42 nm is selected because the average emissivity in this wavelength range greatly contributes to heat conduction.

Further, the low thermal expansion ceramics of the present invention is
The coefficient of thermal expansion at 0 to 20 ° C. is 1 × 10 ⁻⁶ / ° C. or less, the average emissivity at wavelengths of 3.33 to 25.42 μm is 80% or more, and the thermal conductivity at room temperature is 3 W. / M · k or more is preferable.

The reason why the thermal conductivity at room temperature is 3 W / m · k or more is that when the thermal conductivity is less than 3 W / m · k, the number of parts of the exposure apparatus that come into contact with the above-mentioned semiconductor manufacturing apparatus parts is small. This is because, in the case of the configuration, the heat generated by the irradiation of the extreme ultraviolet rays cannot be quickly released through these parts, and the temperature rise cannot be suppressed.

The low thermal expansion ceramics of the present invention are
After the prepared glass raw material is melted, molded, and gradually cooled, a heat treatment for generating crystal nuclei and a heat treatment for promoting crystallization are performed, and the main crystal phase developed is β-quartz solid solution (β-
SiO ₂ solid solution) and / or β-quartz (β-SiO ₂ ).
And the total crystal amount of the main crystal phase is 60 to 70% by weight, and Al ₂ O ₃ 25 to 30% by weight, P ₂ O ₅ 0.1 to 10% by weight, and Li ₂ O0 as auxiliary components. 1 to 6% by weight, TiO ₂ 0.1 to 4% by weight, ZrO ₂ 0.1 to 4% by weight, ZnO 0 to 4% by weight, MgO 0 to ₂ % by weight, K ₂
A glass ceramic containing 0.1 to ₂ % by weight of O and 0.1 to ₂ % by weight of Na ₂ O is preferable.

Here, the solid solution refers to one in which a part of β-quartz crystal is replaced or atoms penetrate into the crystal.

The above-mentioned main crystal phase is a β-quartz solid solution (β-Si
O ₂ solid solution) and / or β-quartz (β-SiO ₂ ) means β-quartz solid solution (β-SiO ₂ solid solution) or β-quartz.
Quartz (β-SiO ₂ ) is an important factor contributing to the coefficient of thermal expansion of the low thermal expansion ceramics of the present invention, and the main crystal having a negative coefficient of thermal expansion in the glass phase having a positive coefficient of thermal expansion. This is because by precipitating the phase, the thermal expansion coefficient of the glass ceramic as a whole can be controlled within a desired numerical range.

Here, the total crystal amount of the main crystal phase is 60
The reason for setting the content to 70% by weight is that if it is less than 60% by weight, the coefficient of thermal expansion may exceed 1 × 10 ⁻⁶ / ° C. depending on the combination of subcomponents, while if it exceeds 70% by weight, sufficient corrosion resistance is obtained. Is not obtained.

The content of Al ₂ O _{3 is set} to 25 to 30% by weight. When the content of Al ₂ O ₃ is less than 25% by weight, it becomes difficult to melt the raw glass and the homogeneity of the raw glass is deteriorated. This is because it is difficult to generate the required amount, while 30
This is because if the content exceeds 10% by weight, the melting point of the raw glass becomes too high and the workability deteriorates.

Li ₂ O is a part of the main crystal phase β
Li, which is an important component that constitutes the quartz solid solution,
_The reason why ₂ O is 0.1 to 6% by weight is that if less than 0.1% by weight, a sufficient amount of crystals cannot be obtained.
This is because if the content is more than wt%, the strength of the glass ceramics obtained after the above heat treatment decreases.

Further, P ₂ O ₅ , TiO ₂ and ZrO ₂ all act as crystal nucleating agents, and all the components are 0.1
It is preferably at least wt%. Meanwhile, P ₂ O ₅ is 10
% By weight, TiO ₂ by 4% by weight or less, and ZrO ₂ by 4% by weight or less means that P ₂ O ₅ exceeds 10% by weight, or TiO ₂ or ZrO ₂ exceeds 4% by weight, respectively. This is because it becomes difficult to melt the raw glass and unmelted material may be generated.

Further, ZnO and MgO are both important components which are constituent elements of the β-quartz solid solution which is a part of the main crystal phase, and each of these components is 4% by weight or less, 2
Weight% or less means that ZnO exceeds 4% by weight or M
This is because when gO exceeds 2% by weight, the coefficient of thermal expansion may exceed 1 × 10 ⁻⁶ / ° C. depending on the combination with other subcomponents. However, when all the main crystal phases are β-quartz, ZnO and MgO may not be included.

Further, K ₂ O and Na ₂ O have the effects of lowering the melting temperature of the glass raw material and suppressing devitrification of the glass during molding.
The reason why the content is set to 2% by weight is that if it is less than 0.1% by weight, the melting temperature of the glass raw material cannot be lowered and devitrification of the glass at the time of molding cannot be sufficiently suppressed.
This is because the strength of the glass-ceramics is reduced when it exceeds.

Further, in order to obtain a homogeneous glass ceramics, As is used as a fining agent when melting the glass raw material.
₂ O ₃ is preferably contained in an amount of 0.1 to ₂ % by weight, and CaO, Fe ₂ O ₃ , and Y ₂ O ₃ may be contained in an amount of 0.2% by weight or less as unavoidable impurities.

The ratio of the main crystalline phase and the subcomponents is
It may be measured using a fluorescent X-ray analyzer or an atomic absorption spectrometer.

Next, a manufacturing method for obtaining the above low thermal expansion ceramics will be described.

First, glass raw materials such as oxides, carbonates, hydroxides, and nitrates are weighed and mixed so as to have the above-mentioned glass-ceramic composition, and the raw materials are put into a crucible or the like, and the temperature is set to 14
Melt with stirring at 00 to 1500 ° C. for 6 to 8 hours,
Obtain raw glass in a clear state. This melted raw glass is molded by casting or the like, and is gradually cooled to remove strain.

Then, the slowly cooled raw glass is heated to a temperature of 6
Hold at 20-800 ° C to promote nucleation. here,
The temperature at which the nucleation is promoted is set to 620 to 800 ° C. because crystal nuclei are not generated even at a temperature lower than 620 ° C. or higher than 800 ° C.

After completion of the nucleation, the temperature is 700 to 950 ° C.
Crystallize with. Here, the temperature for crystallization is 700
The reason why the temperature is set to 950 ° C. is that if the temperature is lower than 700 ° C., a sufficient amount of the main crystal phase does not grow, and if the temperature is higher than 950 ° C., the above-mentioned raw glass melts and crystals that lower the Young's modulus such as β-spodumene are deposited. Because.

After completion of the above crystallization, it is annealed at a rate of 50 ° C./hr or less. Here, the slow cooling rate is set to 50 ° C./hr, because crystals having a negative coefficient of thermal expansion are precipitated, and therefore, rapid cooling at a rate exceeding 50 ° C./hr may cause cracks. Is.

Further, the low thermal expansion ceramics of the present invention can be made into a cordierite-based sintered body, and the manufacturing method in that case will be described.

First, the average particle size is 10 μm or less and the wavelength is 3.
After adding the rare earth oxide powder having an average particle size of 10 μm or less at a ratio of 1 to 20% by weight to the cordierite powder having an average emissivity at 33 to 25.42 μm of 94% or more, a ball mill or the like is sufficiently used. To obtain a mixed powder. Here, the emissivity of the cordierite powder is set to be 94% or more, when the emissivity is less than 94%, the wavelength is 3.33 to 2
This is because the average emissivity of the cordierite-based ceramics that has undergone the molding, firing, and polishing steps at 5.42 μm is less than 80%. In addition, 1% by weight of rare earth oxide powder
The above is because the addition of 1 wt% or more of the rare earth oxide powder causes the rare earth oxide powder to react with the components of cordierite in the subsequent firing step to form a liquid phase, so that the firing at a low temperature is performed. This is because the temperature range in which sintering can be achieved and sintering can be performed can be expanded to 350 ° C.

To obtain cordierite powder having an average particle size of 10 μm or less and an average emissivity of 94% or more at a wavelength of 3.33 to 25.42 μm, talc having an average particle size of 5 to 10 μm, It may be adjusted by pulverizing and mixing kaolin having an average particle diameter of 2 to 10 μm and alumina having an average particle diameter of 4 μm or less as raw materials.

The content of the rare earth oxide powder is set to 20% by weight or less, that is, when the rare earth oxide powder exceeds 20% by weight, the coefficient of thermal expansion of the low thermal expansion ceramics at 0 to 20 ° C. is 1 × 10 ^-6 / This is because it exceeds ℃.

The rare earth elements forming the above rare earth oxide powder include Y, Yb, Lu, Er, Ce and N.
d, Sm, etc. are mentioned, and among these, Y and Yb are preferable because they can be obtained at a low cost. Further, this rare earth element exists in the grain boundary of the cordierite crystal, but this rare earth element is RE ₂ O ₃ .SiO ₂ or RE ₂ O ₃ .2.
It preferably exists as a silicate compound crystal phase such as SiO ₂ (RE: rare earth element). This is because crystallization of the grain boundary phase can further reduce the thermal expansion.

Next, the above-mentioned mixed powder is molded into a desired shape by a desired molding means such as a die press, a cold isostatic press, an extrusion molding, etc.

Then, the above-mentioned molded body is heated in the atmosphere or an inert gas atmosphere such as Ar at a temperature of 1100 to 145.
The low thermal expansion ceramics according to the present invention can be obtained by firing at 0 ° C. and gradually cooling at a temperature lowering rate of 100 ° C. or more per hour.

Here, the firing temperature is 1100 to 1450 ° C.
The reason is that a dense sintered body having a relative density of 95% or more cannot be obtained at a temperature lower than 1100 ° C.
This is because if the temperature exceeds 0 ° C, the cordierite will be dissolved. Further, by setting the rate to 100 ° C./hour or more per hour, the thermal expansion coefficient of the low thermal expansion ceramics at 0 to 20 ° C. can be further lowered, which is preferable.

In particular, in order to accelerate the densification, a mixed powder of cordierite powder and rare earth oxide powder is hot-press fired or the like under a pressure of 10 MPa or more to 110.
The firing is preferably performed at a temperature of 0 to 1450 ° C. In this firing, it is preferable to store the molded body in a silicon carbide-based or alumina-based bowl and perform firing. In order to further densify the molded body, 900 to 1400 ° C under a pressure of 100 MPa or more in a non-oxidizing gas atmosphere such as Ar or N ₂ or in an oxygen atmosphere.
It is also possible to carry out hot hydrostatic pressure treatment at the temperature of.

Further, the above-mentioned silicate compound is obtained by heat-treating the above-mentioned sintered body at a temperature of 1100-1400 ° C. in an atmosphere of non-oxidizing gas such as Ar or N ₂ to promote crystallization of the cordierite grain boundaries. The crystal phase can be precipitated, and the holding time of the heat treatment is preferably 4 hours or more from the viewpoint of further lowering the coefficient of thermal expansion and increasing the average emissivity.

As described above, the low thermal expansion ceramics of the present invention is applied to the reticle, reticle stage, mirror, wafer stage,
The case of using it for a semiconductor manufacturing device component such as a wafer stage position measuring mirror has been described. However, a vacuum such as an electron beam exposure device, a weak magnetic detection device applying a SQUID (superconducting quantum interference device), a scanning electron microscope, etc. It can also be used as a mirror used in a required apparatus, a susceptor for holding a wafer in a film forming apparatus or an etching apparatus, a vacuum chuck, or various jigs in a semiconductor manufacturing process or a structural member for a vacuum apparatus.

[0050]

EXAMPLES Examples of the low thermal expansion ceramics of the present invention will be described below.

(Example 1) Purity 99% or more, average particle size 3
μm and cordierite powder having an average emissivity of 94%, Y ₂ O ₃ , Yb ₂ O ₃ and Er ₂ having an average particle size of 1 μm.
O ₃ and CeO ₂ rare earth element oxide powders were mixed at the ratios shown in Table 1 and then mixed in a ball mill for 24 hours to obtain mixed powders. Next, the mixed powder was press-molded to obtain a molded body, and the molded body was fired under the firing conditions shown in Table 1 to obtain a sintered body.

Sample No. 10-15,1
Regarding 8, 19, 22, 23, 26 and 27, hot isostatic treatment was performed under the conditions shown in Table 1 after sintering. Thereafter, the obtained sintered body was subjected to processing such as grinding or polishing to obtain samples for thermal expansion coefficient measurement, average emissivity measurement, and thermal conductivity measurement.

Here, the size of the sample for measuring the thermal expansion coefficient, the sample for measuring the average emissivity, and the sample for measuring the thermal conductivity are 3 mm in width × 4 mm in thickness × 15 mm in length, respectively.
Diameter 47 mm x thickness 2 mm, diameter 10 mm x thickness 2.
And 5 mm, the surface roughness R _a in Table 1 is a top and bottom surface of the surface roughness of the average emissivity measurement sample.

As a comparative example, the above-mentioned samples made of alumina ceramics and quartz were also prepared.

Here, a sample for measuring the coefficient of thermal expansion is used, and 0 to 0 in accordance with JIS R 1618 (1994).
The thermal expansion coefficient at 20 ° C. was measured.

Regarding the average emissivity, a sample for average emissivity measurement was set in a far infrared spectroradiometer (JIE-E500 manufactured by JEOL Ltd.), and the surface temperature of the sample was set to 36 ° C. Wavelength 3.33 to 25.42
The average emissivity in μm was calculated.

Further, using a sample for measuring thermal conductivity, J
The thermal conductivity at room temperature was measured according to ISR 1611 (1991).

Coefficient of thermal expansion, average emissivity,
Table 1 shows the measurement results of the thermal conductivity.

[0059]

[Table 1]

As can be seen from Table 1, No. 1 which is the low thermal expansion ceramics of the present invention. 1-8, 10-14, 16-2
The coefficient of thermal expansion of No. 7 is as low as 1 × 10 ⁻⁶ / ° C. or less, and the average emissivity is 80% or more, which is good. Also, the above No
The thermal conductivity of 1-8, 10-14, 16-27 is also 3 W / m
・ Higher than k and good.

Example 2 First, glass raw materials were weighed and mixed so as to have the composition of the glass ceramics shown in Table 2, put in a crucible, and then melted with stirring at a temperature of 1450 ° C. for 7 hours and clarified. A raw glass in a simple state was obtained. The melted raw glass was cast by casting and gradually cooled to remove strain.

Next, the slowly cooled raw glass is heated to a temperature of 7
It was kept at 00 ° C to generate crystal nuclei. After the crystal nucleation was completed, the crystals were crystallized at a temperature of 830 ° C. and then gradually cooled at a rate of 50 ° C./hr or less. Then, the obtained glass ceramics were subjected to processing such as grinding or polishing to obtain samples for thermal expansion coefficient measurement, average emissivity measurement, and thermal conductivity measurement.

Here, the size of the thermal expansion coefficient measuring sample, the average emissivity measuring sample, and the thermal conductivity measuring sample were 3 mm wide × 4 mm thick × 15 mm long, respectively.
Diameter 47 mm x thickness 2 mm, diameter 10 mm x thickness 2.
And 5 mm, the surface roughness R _a in Table 1 is a top and bottom surface of the surface roughness of the average emissivity measurement sample.

Here, a sample for measuring the coefficient of thermal expansion is used, and it is 0 to 0 in accordance with JIS R 1618 (1994).
The thermal expansion coefficient at 20 ° C. was measured.

Regarding the average emissivity, a sample for measuring the average emissivity was set in a far infrared spectroradiometer (JIE-E500, manufactured by JEOL Ltd.), and the surface temperature of the sample was set to 36 ° C. Wavelength 3.33 to 25.42
The average emissivity in μm was calculated.

Further, using a sample for measuring thermal conductivity, J
After measuring the thermal conductivity at room temperature in accordance with ISR 1611 (1991), the ratio of the main crystal phase and the subcomponents other than Li ₂ O was measured by a fluorescent X-ray analyzer (PW-1404 manufactured by Nippon Phillips). , Li ₂ O by atomic absorption spectrometer (Seiko Denshi Kogyo (SAS7500))
Was measured.

Coefficient of thermal expansion, average emissivity,
Table 2 shows the results of measuring the thermal conductivity and the ratios of the main crystal phase and the subcomponents.

[0068]

[Table 2]

As can be seen from Table 2, No. 1 which is the low thermal expansion ceramics of the present invention. The coefficient of thermal expansion of 1 to 45 is as low as 1 × 10 ⁻⁶ / ° C. or less, and the average emissivity is 80.
%, Which is high and good. In addition, the above No. The thermal conductivity of 1 to 45 is as high as 3 W / m · k or more, which is excellent.

[0070]

As described above, the coefficient of thermal expansion at 0 to 20 ° C. is 1 × 10 ⁻⁶ / ° C. or less and the wavelength is 3.33 to
By using low thermal expansion ceramics having an average emissivity of 80% or more at 25.42 μm, it is possible to reduce deformation of the material itself due to heat and increase heat transfer due to radiation. By using it, it is possible to prevent deterioration of exposure and transfer accuracy.

The thermal conductivity at room temperature is 3.0 W /
By setting m / k or more, heat transfer due to heat conduction can be increased. Therefore, when it is used for a semiconductor manufacturing apparatus component, similarly, it is possible to prevent deterioration of exposure transfer accuracy.

The rare earth oxide powder was added to and mixed with cordierite powder having an average emissivity of 94% or more at a wavelength of 3.33 to 25.42 μm. After molding the mixed powder by a desired molding means, by firing at a temperature of 1100 to 1450 ° C.,
The average emissivity at a wavelength of 3.33 to 25.42 μm is 8
It is possible to obtain a dense sintered body having a thermal expansion coefficient of 0% or more and a thermal expansion coefficient of 1 × 10 ⁻⁶ / ° C. or less at 0 to 20 ° C.

Further, the mirror of the present invention is a mirror using the above low thermal expansion ceramics, and when used in a vacuum, the mirror itself can reduce deformation due to heat and increase heat transfer by radiation. Therefore, for example, when the mirror is arranged at a predetermined position in the device where a vacuum is required, the reliability of the device can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an extreme ultraviolet reduction projection exposure apparatus using a low thermal expansion ceramics of the present invention.

[Explanation of symbols]

1: Illumination optical system 2: Reticle (mask) 3: Reticle stage 4: Mirror 5: Wafer 6: Wafer stage 7: Mirror for wafer stage position measurement 8: Chamber

Claims (5)

[Claims] 1. The coefficient of thermal expansion at 0 to 20 ° C. is 1 × 10.
^-6 / ° C or less and an average emissivity at a wavelength of 3.33 to 25.42 µm is 80% or more, a low thermal expansion ceramics. 2. The low thermal expansion ceramics according to claim 1, which has a thermal conductivity of 3 W / m · k or more at room temperature. 3. A rare earth oxide powder is added at a ratio of 1 to 20% by weight to cordierite powder having an average emissivity of 94% or more at a wavelength of 3.33 to 25.42 μm,
A low thermal expansion ceramics characterized by being obtained by molding the mixed powder obtained by mixing with a desired molding means and then firing at a temperature of 1100 to 1450 ° C. 4. A component for a semiconductor manufacturing apparatus, which is made of the low thermal expansion ceramics according to any one of claims 1 to 3. 5. A mirror comprising the low thermal expansion ceramics according to claim 1 and used in a vacuum.