JP2003045787A - Method for using photocatalyst, photocatalyst unit, and projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus that use a photocatalyst for decomposing an organic matter that is an impurity in a vacuum-ultraviolet optical system. SOLUTION: An organic matters, contained in gas in an optical system, is decomposed by a photocatalyst in atmosphere having sufficient oxygen, and the oxygen and a decomposition product after reaction completion are adsorbed and removed, thus eliminating impurities inside the optical system.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of using a photocatalyst, and an optical system and a projection exposure apparatus using the same.

[0002]

2. Description of the Related Art With the high integration of semiconductor devices, projection exposure apparatuses used in an important photolithography process for manufacturing the semiconductor devices have made great strides. This high integration is largely due to the shorter wavelength of the exposure light.
In recent years, a krypton fluoride excimer laser (KrF excimer laser) having an output wavelength of 248 nm has been put into practical use as an exposure light source, and more recently, an argon fluoride excimer laser (ArF excimer laser) having an output wavelength of 193 nm has been used. A projection exposure apparatus using a light source is also being put into practical use.

Light having a wavelength of about 120 nm to 200 nm belongs to the vacuum ultraviolet region, and it is difficult for the light to pass through the air. This is because light energy is absorbed by substances such as oxygen molecules and carbon dioxide molecules in the air. Since the ArF excimer laser also emits light in the above wavelength range, the light absorbing substance contained in the air in the exposure light path absorbs the exposure light. for that reason,
Exposure is difficult in a conventional air atmosphere. Therefore, it has been proposed to replace the air in the exposure light path with an inert gas or the like to reduce the concentration of oxygen molecules, carbon dioxide molecules and the like for exposure. Also, in a projection exposure apparatus that uses an ArF excimer laser or a light source with a shorter wavelength, the exposure light is caused by impurities (mainly organic substances) present in the exposure optical path of the optical system (illumination optical system and projection optical system). Is absorbed and the transmittance of the optical system is lowered. The impurities may be substances originating inside the exposure apparatus, substances originating from an inert gas introduced into the exposure optical path, other substances present in the clean room, etc. in the gas state in the optical system, or solid substances. It becomes a liquid or liquid and adheres to the surface of the optical element. By the way, in recent years, attempts have been made to oxidize and decompose organic substances that are impurities by using a photocatalyst. Here, the photocatalyst refers to a substance which has an action of decomposing surrounding substances by generating electrons and holes on its surface when receiving light energy. Usually, the photocatalyst is used in an atmosphere in which oxygen is sufficiently present, and active oxygen is generated by reacting electrons and holes generated on the surface with oxygen, and oxidizes and decomposes organic substances. The light energy required to generate electrons and holes is supplied by light of a wavelength having an energy larger than the band gap of the substance.

[0004]

However, when organic substances are decomposed using a photocatalyst, carbon dioxide is produced as one of the final products. This is because carbon, which is one of the elements constituting the organic matter, becomes carbon dioxide due to the oxidation reaction. When carbon dioxide is present in the exposure light path,
Since it absorbs the ultraviolet light which is the exposure light, the transmittance is lowered. Therefore, when the oxidative decomposition reaction of the organic substance by the photocatalyst is continuously performed, there is a problem that the exposure becomes difficult due to the decrease in the transmittance. Further, as described above, in the optical system and the exposure apparatus that use vacuum ultraviolet light as a light source, the atmosphere of the optical system is a low oxygen atmosphere or an oxygen free atmosphere. In a photoreaction by a photocatalyst in a low oxygen atmosphere or an oxygen-free atmosphere, an organic substance as an impurity becomes a low molecule due to a decomposition reaction. This low-molecular substance is an active substance which has a low molecular weight but can become an organic polymer by a polymerization reaction. Many of them also have the property of absorbing vacuum ultraviolet light. Therefore, light absorption or polymerization reaction may occur in the optical system, resulting in a decrease in transmittance. The present invention solves such a problem, and decomposes an organic matter, and carbon dioxide produced by decomposition from the organic matter, water, and a method of using a photocatalyst for removing an organic matter by suppressing mixing of the organic matter into an optical system, Another object of the present invention is to provide a photocatalyst unit and a projection exposure apparatus for removing organic substances in the system by using a photocatalyst.

[0005]

According to a first aspect of the present invention, in a method of using a photocatalyst for decomposing organic matter in a container that can be sealed by irradiation with ultraviolet light, a decomposition step of oxidatively decomposing the organic matter by the photocatalyst. At least one of an oxygen removing step of removing oxygen contained in the gas in the container and a decomposition reaction product removing step of removing the decomposition reaction product produced in the decomposition step from the gas. It is characterized by having one or the other. With this configuration,
It is possible to decompose and remove organic substances.

According to a second aspect of the present invention, in the method of using the photocatalyst according to the first aspect, the oxygen removal step is performed after the decomposition step. With this configuration, it is possible to decompose and remove organic substances. The invention of claim 3 is the method of using the photocatalyst of claim 1, wherein the decomposition reaction product removing step is performed after the decomposition step. With this configuration, it is possible to decompose and remove organic substances.

According to a fourth aspect of the present invention, in the method of using the photocatalyst according to the first aspect, the method further comprises an oxygen adding step of adding oxygen to the gas in the container, wherein the oxygen adding step precedes the decomposing step. It is characterized by performing. With this configuration, it is possible to decompose and remove organic substances.

According to the inventions of claims 5 and 6, in the invention of claim 1, the photocatalyst is TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , K ₄ Nb ₆ O ₁₇ , KCa.
₂ Nb ₃ O ₁₀ or KSr ₂ Nb ₃ O ₁₀ . With this configuration, it is possible to decompose and remove organic substances. According to a seventh aspect of the present invention, in the method of using the photocatalyst according to the first aspect, the oxygen removing step is a step of adsorbing the oxygen to the oxygen adsorbing means. With this configuration, it is possible to decompose and remove organic substances.

The invention of claim 8 is the method of using the photocatalyst of claim 1, wherein the decomposition reaction product removing step is a step of adsorbing carbon dioxide and water to the adsorbing means. With this configuration, it is possible to decompose and remove organic substances. According to a ninth aspect of the present invention, in the method of using the photocatalyst according to the eighth aspect, the step of removing the decomposition reaction product further comprises a step of adsorbing the organic substance and a low-molecular organic substance generated in the decomposition step to an adsorption means. It is characterized by including. With this configuration, it is possible to decompose and remove organic substances.

According to a tenth aspect of the present invention, in the method of using the photocatalyst according to the fourth aspect, the oxygen addition step includes oxygen molecules in approximately the same number of moles with respect to carbon atoms contained in the organic substance, and in the organic substance. It is characterized in that it is a step of adding the total amount of oxygen, which is the total number of moles of oxygen molecules which is approximately one fourth of the number of hydrogen atoms. With this configuration, it is possible to decompose and remove organic substances.

According to the invention of claim 11, in the method of using the photocatalyst according to claim 1, the gas in the container is a gas existing in an optical system using light having a wavelength of 200 nm or less as a light source. It is characterized by being a gas. With this configuration, it is possible to decompose and remove organic substances.

According to a twelfth aspect of the present invention, in the method of using the photocatalyst according to the first aspect, the gas in the container is the gas present in an optical system of a projection exposure apparatus using light having a wavelength of 200 nm or less as the light source. It is characterized in that it is a gas introduced into the inside. With this configuration, it is possible to decompose and remove organic substances.

A thirteenth aspect of the present invention includes a container capable of being closed,
In a photocatalytic unit consisting of a photocatalyst provided in the container, an oxygen removing means for removing oxygen contained in the gas in the container, and carbon dioxide, water and organic substances contained in the gas in the container. And a fan for generating an airflow in the container. With this configuration, it is possible to decompose and remove organic substances.

According to a fourteenth aspect of the present invention, in the photocatalyst unit according to the thirteenth aspect, the fan directs an air flow so that the photocatalyst is on the upstream side and the oxygen removing means and the decomposition reaction product removing means are on the downstream side. A photocatalyst unit characterized by being generated. With this configuration, it is possible to decompose and remove organic substances.

According to a fifteenth aspect of the present invention, in the photocatalyst unit according to the thirteenth aspect, the container has a gas inlet for introducing gas from the outside and a gas outlet for discharging the gas to the outside. With this configuration, it is possible to decompose and remove organic substances.

According to a sixteenth aspect of the present invention, in the photocatalyst unit according to the fifteenth aspect, all or part of the gas introduced from the gas introduction port comes into contact with the photocatalyst. With this configuration, it is possible to decompose and remove organic substances. The invention according to claim 17 is the photocatalyst unit according to claim 13, further comprising oxygen introducing means for introducing oxygen from the outside of the container into the container, wherein the oxygen introducing means is provided in an air flow inside the container rather than the photocatalyst. On the other hand, it is characterized in that it is provided on the upstream side. With this configuration,
It is possible to decompose and remove organic substances.

The inventions of claims 18 and 19 are contracts.
In the photocatalyst unit according to claim 13, the photocatalyst is
TiO₂, Nb₂O_Five, Ta₂O_Five, K_FourNb₆O₁₇, KCa₂Nb₃O_TenOr KSr₂N
b₃O_{1 0}A photocatalytic unit characterized by being. Claim
The invention of 20 provides a photocatalytic unit according to claim 15,
Gas discharged from the container through the gas discharge port
It is characterized in that temperature control means for controlling the temperature of the
It With this configuration, organic substances can be decomposed and removed.
Noh.

According to a twenty-first aspect of the invention, in the photocatalyst unit according to the twentieth aspect, the temperature adjusting means makes the temperature of the gas discharged from the gas outlet substantially equal to the temperature of the gas introduced from the gas inlet. It is characterized by matching. With this configuration, it is possible to decompose and remove organic substances.

According to a twenty-second aspect of the present invention, in the photocatalyst unit according to the seventeenth aspect, an organic substance sensor for measuring an organic substance contained in a gas introduced into the container, and an organic substance sensor in the container based on a signal from the organic substance sensor. And an oxygen addition amount adjusting means capable of adjusting the amount of oxygen to be added. With this configuration, it is possible to decompose and remove organic substances.

In a twenty-third aspect of the present invention, an exposure light source for emitting ultraviolet light, an illumination optical system for irradiating the mask with the ultraviolet light, and an illuminating light that has passed through the mask on which a circuit pattern is drawn are coated with a photosensitizer. In a projection exposure apparatus comprising a projection optical system for forming an image on the formed wafer and a stage for moving the wafer to an appropriate exposure position, the illumination optical system and the projection optical system can be wholly or partially sealed. The photocatalyst unit according to claim 13 is provided in the projection exposure apparatus via a gas inlet and a gas outlet to enable movement of an internal gas between the projection exposure apparatus and the photocatalyst unit. It is characterized by having done. With this configuration,
It is possible to decompose and remove organic substances.

According to a twenty-fourth aspect of the invention, in the projection exposure apparatus according to the twenty-third aspect, the ultraviolet light is light having a wavelength of 200 nm or less. With this configuration, it is possible to decompose and remove organic substances.

[0022]

DETAILED DESCRIPTION OF THE INVENTION

[0023]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a method of using the photocatalyst according to the present invention. As shown in FIG. 1, a quartz plate having TiO ₂ adhered to its surface as a photocatalyst 1 is placed inside a container 3 made of stainless steel that can be sealed. Container 3
Is provided with a window 4 made of synthetic quartz or the like that transmits ultraviolet light. As the ultraviolet light irradiation means 2, a mercury lamp is installed so that the surface of TiO ₂ is irradiated with ultraviolet light through the window 4. The ultraviolet light irradiation means 2 may be an ultraviolet light laser such as a KrF excimer laser, an ArF excimer laser, or a nitrogen laser, an ultraviolet ray generation lamp such as an excimer lamp, a semiconductor light emitting element, or a semiconductor laser, instead of a mercury lamp.

Inside the container 3, the gas is introduced through the gas inlet 8.
An internal atmosphere gas of 0 is introduced. Container 20 is optical system 1
It is a container that can contain 0. Oxygen is introduced into the container 3 from the oxygen introducing means 5. Fan 3 in container 3
0 is set. The fan 40 allows the internal atmosphere gas to flow in a fixed direction. The direction is as follows: the gas inlet 8, the oxygen inlet 5, the photocatalyst 1, the oxygen adsorber 6, the adsorber 7, and the gas outlet 9 in that order.
Is the direction in which the internal gas flows. Further, the airflow in the container 3 may be made to flow in the above-described direction by using natural convection or a differential pressure of gas pressure on the side of the optical system 10 instead of the fan 40. This is because the gas inside the container 3 flows backward and the introduced oxygen and the decomposition reaction product by the photocatalyst 1 are transferred to the optical system 10.
This is because it is not mixed in with. For this reason, it is better to provide a backflow preventing means (not shown) in the gas inlet 8.

An optical system using vacuum ultraviolet light as a light source,
It is sensitive to temperature changes, and even a slight change in temperature changes the optical characteristics. Therefore, a temperature adjusting means 21 for compensating the decomposition reaction by the photocatalyst 1 and the temperature change by the ultraviolet light irradiating means 2 is provided. For this, a heater, a heat pipe, a Peltier element or the like is used. By adjusting the temperature of the gas discharged from the container 3 to an appropriate temperature by the temperature adjusting means 21, the temperature of the atmosphere of the optical system 10 contained in the container 20 can be maintained within a certain range. Thereby, the optical system 10 can be maintained with high accuracy.

The method for carrying out the present invention will be described below.
The surface of the photocatalyst 1 is irradiated with ultraviolet light from the ultraviolet light irradiation means 2 to excite the photocatalyst 1. When oxygen contacts the excited photocatalyst 1, active oxygen is generated. When the organic matter comes into contact with the active oxygen, the active oxygen and the organic matter cause an oxidative decomposition reaction. As a result, the organic matter is decomposed into decomposition reaction products such as carbon dioxide and water. This process is called a decomposition process.

If oxygen is insufficient in this decomposition step, the decomposition of the organic matter becomes insufficient, and a low molecular weight organic matter may be produced. This low molecular weight organic substance is a reaction-active substance and is changed into a high molecular weight organic substance by a polymerization reaction. Since this high molecular organic substance is an impurity, it adversely affects the optical system 10. Therefore, it is necessary to supply a sufficient amount of oxygen so that the reaction is sufficiently performed so as not to generate the low molecular weight organic matter.

Since the light source of the optical system 10 is vacuum ultraviolet light, it is usually used in a low oxygen state. For decomposing a gaseous organic substance in a low oxygen state, it is desirable to supply oxygen before the decomposition reaction for the above reason. The step of adding oxygen to the gas inside the container 3 is referred to as the oxygen adding step. The decomposition step is performed after oxygen is added to the gas inside the container 3 in the oxygen addition step.

After the decomposition step, oxygen is removed. This is because oxygen absorbs vacuum ultraviolet light having a wavelength of 200 nm or less. Therefore, when oxygen is mixed in the optical system 10 that uses vacuum ultraviolet light as a light source, the transmittance of the light from the light source decreases,
The performance of the optical system deteriorates.

Oxygen is removed by adsorbing oxygen to the oxygen adsorbing means 6. This adsorption process is called an oxygen removal process. The oxygen adsorbing means 6 is an oxygen adsorbing means for removing oxygen by an oxidation reaction of Fe or adsorption by zeolite. The oxygen removal step needs to be performed after the reaction is completed in the decomposition step.

Further, carbon dioxide produced in the decomposition step,
Water and organic substances that have not been sufficiently decomposed during the decomposition reaction (these are referred to as decomposition reaction products) and organic substances that have not undergone the decomposition reaction are removed. These substances absorb the light from the light source or are deposited on the surface of the optical element to reduce the transmittance, which causes the performance of the optical system to be deteriorated. Adsorption means 7 for adsorbing organic substances and organic substance decomposition reaction products
Is composed of substances that adsorb the respective substances. Carbon dioxide adsorbing means using activated carbon, zeolite, activated alumina, silica gel, etc., water adsorbing means using silica gel, zeolite, etc., organic substances using activated carbon, zeolite etc. (organic substances and organic substances not fully decomposed) It is composed of a suction means. These adsorption means are
It is placed in a container such as a net and installed inside the container 3.
Oxygen, carbon dioxide, water, and organic substances (impurities) are removed from the gas by these adsorption means. This removal process is called a decomposition reaction product removal process. The decomposition reaction product removing step is performed after the decomposition step.

The gas thus cleaned of the organic substances by decomposition is returned to the optical system 10 through the gas outlet 9. As a result, impurities in the optical system 10 are removed, and the influence on the optical element is reduced. In order to confirm the effect of removing impurities, a predetermined amount of gas passed through the oxygen adsorbing means 6 and the adsorbing means 7 is extracted, and the extracted internal gas is set in gas chromatography. According to the result of analysis of the internal gas by gas chromatography, the gas hardly contained optical elements such as oxygen, carbon dioxide, and organic substances and substances that affect the exposure light.

As a comparative example, a photocatalytic unit without the oxygen adsorbing means 6 and the adsorbing means 7 is connected to the container 20 of the optical system 10, and the internal gas near the gas outlet is set for gas chromatography. According to the analysis results, oxygen, carbon dioxide, water, and organic substances were detected, respectively, and it was found that the amount deteriorates the performance of the optical system.

Therefore, according to the present invention, it has been found that it is possible to decompose the organic substance inside the optical system and also to remove the substance that is generated during the decomposition reaction and affects the optical system.

[0035]

Example 2 Except for using Nb ₂ O ₅ instead of TiO ₂ as the photocatalyst 1, the organic gas decomposition treatment of the gas inside the optical system 10 was performed and the exhaust gas was analyzed by the same method as in Example 1. As a result, almost the same as in Example 1, the impurities in the optical system 10 were removed, and the influence on the optical element was reduced. Photocatalyst 1 was replaced with Ta ₂ O ₅ , K ₄ Nb ₆ O ₁₇ , KCa ₂ Nb ₃ O ₁₀ and KSr ₂ Nb ₃ O ₁₀ in order, and the same analysis was carried out. The results were almost the same as in Example 1. The organic matter in the system 10 was removed, and the influence on the optical element was reduced.

[0036]

Third Embodiment FIG. 2 is a conceptual diagram showing an exposure apparatus according to the present invention. The contents will be described below. The exposure apparatus of the present invention has at least a wafer stage 30 on which a substrate W coated with a photosensitive agent placed on the surface 301a can be placed.
1. Illumination optical system 101 for irradiating vacuum ultraviolet light of a prepared wavelength as exposure light to transfer the pattern of the mask R prepared on the substrate W, and for supplying exposure light to the illumination optical system 101 A light source 100, a first surface P1 (object surface) on which a mask R for projecting an image of the pattern of the mask R is arranged on the substrate W, and a second surface (image surface) matched with the surface of the substrate W. Projection optical system 50 placed between
Including 0. The illumination optical system 100 includes a mask R and a wafer W.
An alignment optical system 110 for adjusting the relative position between the mask R and the wafer stage 30 is also included.
It is arranged on a reticle stage 201 which can move parallel to the surface of the first unit. The reticle exchange system 200 exchanges and carries the mask R set on the reticle stage 201. The reticle exchange system 200 is the wafer stage 3
No. 01 surface 301a includes a stage driver for moving the reticle stage 201 in parallel.
The projection optical system 500 has an alignment optical system applied to a scan type exposure apparatus. Such an exposure device is housed in a container 23 that can be sealed. The container 23 is made of stainless steel, and the internal gas can be exchanged. The container 13, which is a photocatalytic unit, is installed in the container 23 via the gas inlet 18 and the gas outlet 19. The container 13 is made of stainless steel and can be sealed. The container 13 is provided with a photocatalyst 11, an oxygen introducing section 15, an oxygen adsorbing means 16 and an adsorbing means 17 for adsorbing organic substances, organic substance decomposition reaction products and the like.

The atmospheric gas of the optical system of the projection exposure apparatus in the container 23 is taken into the container 13 through the gas introduction port 18.
The fan 42 provided in the container 13 allows the gas inside the container 13 to flow from the gas inlet 18 to the gas outlet 19. Container 23 taken inside the container 13
The gas inside contacts the photocatalyst 11 excited by the ultraviolet light emitted from the ultraviolet light irradiation means 12 through the window 14. The excited photocatalyst 11 is contacted with oxygen introduced from the oxygen introduction part 15, and active oxygen is generated in the vicinity of the photocatalyst 11. Due to this active oxygen, the organic substances contained in the gas are
It is decomposed into carbon dioxide and water by the oxidative decomposition reaction. Oxygen is adsorbed and removed by the oxygen adsorbing means 16. Other components are adsorbed and removed by the adsorbing means corresponding to the respective components contained in the adsorbing means 17. The cleaned gas is returned to the container 23 through the gas outlet 19. As a result, the organic substances in the container 23 were removed, and the influence on the optical element was reduced. Also, the light source 1
The ultraviolet light from 00 may be used as the light for exciting the photocatalyst 11. As for the method, leakage light of each optical element of the illumination optical system 101 and the projection optical system 500 or a branch in the optical path may be provided to irradiate the photocatalyst 11 through the window 14, or the light from the light source 100 may be irradiated. The irradiation may be performed directly or indirectly.

Only a part of the optical system may be sealed with the container 23. Further, the illumination optical system 101 and the projection optical system 500 may be sealed as independent systems and the containers 23 may be provided respectively.

[0039]

[Embodiment 4] FIG. 3 is a schematic view showing a method of using the photocatalyst according to the present invention. The contents will be described below. Container 3
If the gas taken in contains a large amount of organic substances, the oxygen necessary for the oxidative decomposition reaction may be insufficient. In such a case, the organic matter may not be sufficiently decomposed, and not only carbon dioxide and water, which are final decomposition products, but also an organic matter having a smaller molecular weight may be generated. These are adsorbed and removed by the adsorbing means 7, but if the adsorbing amount becomes large, the adsorbing performance of the adsorbing means 7 will deteriorate. Further, when the supplied oxygen is extremely excessive, the adsorption performance of the adsorption means 6 is deteriorated.

Therefore, as shown in FIG. 3, a control valve is provided in the oxygen introducing means 5 provided in the container 3, and an oxygen supply control device is further connected to this control valve. This makes it possible to control the amount of oxygen supplied to the inside of the container 3. An organic substance sensor 41 for measuring the amount of organic substances present in the optical system is connected to the oxygen supply control device. Organic matter sensor 4
The oxygen addition amount adjusting means supplies an appropriate amount of oxygen with respect to the amount of the organic matter detected by 1. At this time, the appropriate amount of oxygen is an amount in which carbon (C) and hydrogen (H) mainly contained in the organic substance are decomposed after reacting with carbon dioxide (CO ₂ ) and water (H ₂ O), respectively. . In terms of the number of moles, the number of moles of oxygen molecules is equal to the number of moles of carbon atoms in the organic substance, which is a quarter of the number of moles of hydrogen atoms. The total amount of carbon and hydrogen can be calculated from the type and amount of the detected organic matter, and the amount of oxygen required can be calculated. The calculated amount of oxygen is controlled so as to be supplied into the container.

As a result, oxygen is excessively supplied,
It is possible to prevent the unreacted organic matter and the insufficiently reacted organic matter from being generated, and the amount of the substance removed by the oxygen adsorbing means 6 and the adsorbing means 7 to increase, thereby preventing the adsorption performance from deteriorating. Therefore, the adsorption efficiency is improved, the organic substance concentration in the optical system 10 can be further lowered, and the influence on the optical element is further reduced.

As described above, the oxygen adsorbing means 6 is a means for adsorbing the oxygen remaining without being consumed in the oxidative decomposition reaction. That is, when all of the oxygen is consumed by the oxidative decomposition reaction, it is sufficient that the oxygen adsorption is not performed. Therefore, in such a system, the oxygen adsorption means 6 may be omitted. By omitting the oxygen adsorbing means 6, the structure can be simplified, and the maintenance process such as replacement of the material that adsorbs oxygen can be omitted, which is efficient. However, the condition that all oxygen is consumed can be calculated by the method described above, but if the oxidative decomposition reaction does not ideally proceed, unreacted oxygen is discharged into the optical system 10.
Therefore, it is usual that the oxygen adsorption means 6 is provided.

When oxygen is sufficiently supplied during the organic substance decomposition reaction, the internal gas may not contain organic substances other than H ₂ O and CO ₂ . In such a system, the structure of the adsorption means 7 may be a structure in which activated carbon or the like for adsorbing organic substances is omitted.

[0044]

As described above, according to the present invention, it is possible to effectively remove the organic substances which are impurities contained in the atmospheric gas in the optical system. Further, thereby, it is possible to reduce the adhesion of impurities to the optical element of the optical system, it is possible to remove the substance that absorbs vacuum ultraviolet light in the atmosphere of the optical system,
The transmittance and optical performance of the optical system can be improved.
Further, in the projection exposure apparatus, there are effects such as improvement of exposure accuracy and improvement of throughput.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method of using a photocatalyst according to the present invention.

FIG. 2 is a configuration diagram schematically showing a projection exposure apparatus according to the present invention.

FIG. 3 is a configuration diagram schematically showing a method of using the photocatalyst according to the present invention.

[Explanation of symbols]

1, 11 Photocatalyst 2, 12 Ultraviolet light irradiation means 3, 13, 20, 23 Sealable container 4, 14 Ultraviolet light transmission window 5, 15 Oxygen introduction part 6, 16 Oxygen adsorption means 7, 17 Adsorption means 8, 18 Gas Inlet 9, 19 Gas outlet 10, 35 Optical system 21 Temperature control means 40, 42 Fan 41 Organic substance sensor 100 UV laser 101 Illumination optical system 500 Projection optical system R Reticle W Wafer

Claims (24)

[Claims] 1. A method of using a photocatalyst for decomposing organic matter in a container that can be sealed by irradiation with ultraviolet light, comprising a decomposing step of oxidatively decomposing the organic matter by the photocatalyst, and further, in a gas in the vessel. Of the photocatalyst characterized by having at least one of an oxygen removal step of removing oxygen contained in the above, and a decomposition reaction product removal step of removing the decomposition reaction product produced in the decomposition step from the gas. how to use. 2. The method of using a photocatalyst according to claim 1, wherein the oxygen removal step is performed after the decomposition step. 3. The method of using a photocatalyst according to claim 1, wherein the decomposition reaction product removing step is performed after the decomposition step. 4. The method for using the photocatalyst according to claim 1, further comprising an oxygen addition step of adding oxygen to the gas in the container, wherein the oxygen addition step is performed before the decomposition step. To use photocatalyst 5. The method of using a photocatalyst according to claim 1, wherein the photocatalyst is TiO ₂ , Nb ₂ O ₅ or Ta ₂ O ₅ . 6. The method of using the photocatalyst according to claim 1, wherein the photocatalyst is K ₄ Nb ₆ O ₁₇ , KCa ₂ Nb ₃ O ₁₀ or KSr ₂ Nb ₃ O _10.
A method for using a photocatalyst characterized by 7. The method of using a photocatalyst according to claim 1, wherein the oxygen removing step is a step of adsorbing the oxygen to an oxygen adsorbing means. 8. The method of using a photocatalyst according to claim 1, wherein the decomposition reaction product removing step is a step of adsorbing carbon dioxide and water to an adsorption means. 9. The method of using a photocatalyst according to claim 8, wherein the decomposition reaction product removing step further includes a step of adsorbing the organic substance and a low-molecular organic substance generated in the decomposition step to an adsorption means. A method of using a photocatalyst characterized by the above. 10. The method of using a photocatalyst according to claim 4, wherein in the oxygen addition step, oxygen molecules having substantially the same number of moles as carbon atoms contained in the organic substance and hydrogen atoms contained in the organic substance are contained. A method of using a photocatalyst, characterized by the step of adding oxygen in an amount of a total of approximately one-fourth the number of moles of oxygen molecules. 11. The method for using the photocatalyst according to claim 1, wherein the gas in the container is a gas in which a gas existing in an optical system having a light source having a wavelength of 200 nm or less is introduced into the container. A method of using the photocatalyst characterized. 12. The method of using a photocatalyst according to claim 1, wherein the gas in the container is a gas in which a gas existing in an optical system of a projection exposure apparatus using a light having a wavelength of 200 nm or less as a light source is introduced into the container. A method for using a photocatalyst characterized by 13. A photocatalyst unit comprising a hermetically sealable container and a photocatalyst provided in the container, wherein oxygen removing means for removing oxygen contained in the gas in the container, and gas in the container A photocatalyst unit comprising: a decomposition reaction product removing means for removing carbon dioxide, water and organic matter contained in the container, and a fan for generating an air flow in the container. 14. The photocatalyst unit according to claim 13, wherein the fan generates an air flow so that the photocatalyst is on the upstream side and the oxygen removing means and the decomposition reaction product removing means are on the downstream side. And photocatalytic unit. 15. The photocatalytic unit according to claim 13, wherein the container has a gas inlet for introducing gas from the outside and a gas outlet for discharging the gas to the outside. 16. The photocatalytic unit according to claim 15, wherein all or part of the gas introduced from the gas introduction port comes into contact with the photocatalyst. 17. The photocatalyst unit according to claim 13, further comprising oxygen introducing means for introducing oxygen from the outside of the container into the container, wherein the oxygen introducing means is arranged with respect to an air flow inside the container rather than the photocatalyst. A photocatalytic unit that is provided on the upstream side. 18. The photocatalyst unit according to claim 13, wherein the photocatalyst is TiO ₂ , Nb ₂ O ₅ or Ta ₂ O ₅ . 19. The photocatalyst unit according to claim 13, wherein the photocatalyst is K ₄ Nb ₆ O ₁₇ , KCa ₂ Nb ₃ O ₁₀ or KSr ₂ Nb ₃ O _10.
A photocatalytic unit characterized by being. 20. The photocatalyst unit according to claim 15, further comprising temperature adjusting means for adjusting the temperature of the gas discharged from the inside of the container through the gas discharge port. 21. The photocatalyst unit according to claim 20, wherein the temperature adjusting means causes the temperature of the gas discharged from the gas outlet to substantially match the temperature of the gas introduced from the gas inlet. And photocatalytic unit. 22. In the photocatalyst unit according to claim 17, an organic substance sensor for measuring an organic substance contained in a gas introduced into the container, and an oxygen amount added to the container based on a signal from the organic substance sensor. A photocatalyst unit, which is provided with an adjustable oxygen addition amount adjusting means. 23. An exposure light source that emits ultraviolet light, an illumination optical system that irradiates the mask with the ultraviolet light, and illumination light that has passed through the mask on which a circuit pattern has been drawn is applied onto a wafer coated with a photosensitive agent. In a projection exposure apparatus comprising a projection optical system for forming an image and a stage for moving a wafer to an appropriate exposure position, the illumination optical system and the projection optical system can be wholly or partly sealed, and The photocatalyst unit according to claim 13 is provided in the projection exposure apparatus via a gas inlet and a gas outlet, and the internal gas can be moved between the projection exposure apparatus and the photocatalyst unit. Projection exposure system. 24. The projection exposure apparatus according to claim 23, wherein the ultraviolet light is light having a wavelength of 200 nm or less.