JP2008294185A - Purifier of liquid for liquid immersion exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purifier of a liquid for liquid immersion exposure by which impurities in the liquid for liquid immersion generated by exposure are efficiently removed, optical properties of the liquid for liquid immersion exposure are stabilized and its reuse is enabled. <P>SOLUTION: The purifier 1 is provided with a container 10 which is provided with an inlet 32 into which an undiluted solution flows and an outlet 33 from which the treatment liquid flows out, two filters 22 and 23 arranged in the container 10 and an adsorbent 20 which fills a space between the two filters 22 and 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a purifier used for purifying a liquid in an immersion type exposure method in which exposure is performed through a liquid filled between an optical element of a projection optical means and a substrate.

  When manufacturing an electronic device such as a semiconductor element or an imaging element, a substrate (wafer, glass plate, etc.) on which an image of a pattern of an original (reticle or mask) is applied via a projection optical means An exposure apparatus (projection type) that transfers to each of the above shot areas is used. In such an exposure apparatus, it is required to improve the resolution of the projection optical means in order to cope with the miniaturization of circuits accompanying the miniaturization and high integration of electronic devices.

  As long as an electronic device is manufactured by a lithography technique, an exposure technique (exposure apparatus) is indispensable, and the exposure wavelength used in the exposure apparatus has been shortened year by year as the circuit becomes finer. Yes. As the electronic device design rule becomes finer from 90 nm to 65 nm, and further to 45 nm, the exposure technology uses an immersion method using ArF laser light using pure water, and a high refractive index instead of pure water. The use of liquids (materials) has evolved, and in the future, exposure technology is expected to advance from immersion methods to the use of extreme ultraviolet light (EUV).

  The present invention has been made against the background of the development of such exposure technology, the use of the high refractive index liquid put to practical use in the immersion method, and the demand for reuse to increase the environment. It is a thing.

For example, Patent Documents 1 to 5 can be cited as related prior art documents.
US Patent Application Publication No. 2005/0286031 International Publication No. 05/119371 Pamphlet WO 06/115268 pamphlet International Publication No. 05/114711 Pamphlet JP 2006-210542 A

  The immersion method (immersion type exposure method) is a method in which the space between the lower surface of the projection optical means and the substrate surface is filled with a liquid, and the wavelength of the exposure light source in the liquid is air when the refractive index of the liquid is n. This is an exposure technique that improves the resolution and enlarges the depth of focus by about n times by utilizing the fact that it becomes 1 / n times the medium. When the exposure wavelength is shortened and the numerical aperture is increased in order to increase the resolution, the depth of focus becomes narrow. Therefore, the immersion method that can expand the depth of focus is a useful exposure technique.

  As the liquid, pure water has been mainly used, but with the miniaturization of the circuit, the use of a liquid having a refractive index larger than that of pure water (refractive index 1.44) is being shifted. For example, Patent Documents 4 and 5 propose an alicyclic hydrocarbon compound such as decalin as an immersion exposure liquid (also simply referred to as an exposure liquid) suitable for the next generation immersion exposure method. ing.

  The alicyclic hydrocarbon compound has a large refractive index in ArF laser light and has excellent properties as an immersion exposure liquid. However, when this exposure liquid with a high refractive index is used for exposure, side effects such as photolysis, oxidation, dehydrogenation and the like may occur due to light irradiation, and the purity of the exposure liquid may be lowered. Further, since the exposure liquid is in contact with the resist film, the purity of the exposure liquid may be lowered even if the components in the resist film are eluted.

  As purity decreases in this way, impurities caused by side reactions and elution absorb light, which reduces the amount of light that reaches the resist film and is necessary to resolve the pattern to the optimal dimensions. There is a risk that the amount of irradiation will decrease. Doing so causes a significant reduction in exposure throughput, and the amount of light varies from one substrate to another depending on the amount of impurities contained in the exposure liquid. As a result, the yield of electronic devices deteriorates and the production efficiency decreases. Invite For this reason, it is not preferable that impurities exist in the exposure liquid.

  However, when the exposure liquid containing impurities as described above is continuously used and made disposable, it is considered that various problems caused by impurities generated by light can be avoided. However, such a response reduces competitiveness due to an increase in running cost accompanying an increase in consumption and an increase in device production cost. Further, when the exposure liquid is the alicyclic hydrocarbon compound (organic compound), the environmental load is increased by discarding. Therefore, it cannot be said that it is a preferable response.

  On the other hand, Patent Documents 2 and 3 disclose a method of recycling an exposure liquid having a high refractive index using an adsorbent. However, in these Patent Documents 2 and 3, although the action of the adsorbent is clear, the specific specifications of the column / container for containing the adsorbent are not disclosed. Therefore, in order to industrialize the reuse of the exposure liquid, it is actually difficult to purify the exposure liquid to a reusable level efficiently without reducing the exposure throughput. I faced a problem.

  The present invention has been made in view of such circumstances, and the problem is that in the mass production process of electronic devices, impurities generated in the immersion exposure liquid by exposure and impurities eluted from the resist film are exposed. Another object of the present invention is to provide a purifier that can be efficiently removed and the optical properties of the immersion type exposure liquid can be stabilized while the immersion type exposure liquid can be reused. As a result of repeated research, it has been found that the above-mentioned problems can be solved by the following means, and the present invention has been completed.

  That is, according to the present invention, a container having an inlet through which a stock solution flows and an outlet through which a processing solution flows out, two filters provided in the container, and an adsorbent filled between the two filters are provided. An immersion type exposure liquid purifier (also simply referred to as a purifier) is provided.

  The stock solution is an immersion type exposure liquid that has not been purified to a reusable level, and the processing solution is an immersion type exposure liquid that has been purified by contact with an adsorbent. The fact that the adsorbent is filled between two filters means that a filter exists between the adsorbent and the inlet and outlet of the container, and the adsorbent is accommodated on the side of the two filters and the container. Refers to embodiment.

  In the purifier according to the present invention, at least the liquid contact portion of the container is preferably formed of any one or more materials selected from a material group consisting of stainless steel, fluororesin, glass, and ceramic. . When at least the liquid contact portion of the container is formed of stainless steel, the stainless steel is subjected to any one or more treatments selected from a surface treatment group consisting of electrolytic polishing treatment and passivation treatment. It is preferable.

  The liquid contact part of the container is a part that can come into contact with the liquid for immersion type exposure. Since it is at least a wetted part of the container, it may be a material that forms not only the wetted part but the entire container. The material for forming the liquid contact part of the container includes a case where it is used as a coating material in addition to constituting a casing (structure) of the container. Moreover, the case where a housing is comprised as two or more composite materials, or is utilized as a coating material is included.

  The purifier according to the present invention preferably has airless couplers at the inlet and outlet of the container.

  In the purifier according to the present invention, the filter is preferably formed of any one or more materials selected from the material group consisting of stainless steel, fluororesin, and ceramic.

  In the purifier according to the present invention, the filter is preferably composed of a porous body. In this case, the maximum pore size of the filter is preferably 1 μm or more and 30 μm or less. A more preferable maximum pore diameter is 2 μm or more and 10 μm or less.

  The purifier according to the present invention has an inlet located on the lower side and an outlet located on the upper side during the purification process of the immersion type exposure liquid, and the immersion type exposure liquid is adsorbed upward in the container. It is preferable to contact the agent. In such an upward flow type purifier, it is preferable to provide an elastic member for pressing one of the two filters on the outlet side located on the upper side. As the elastic member, a spring is preferably used, and a stainless steel coil spring can be particularly preferably used.

  In the purifier according to the present invention, the filling rate of the adsorbent is preferably 15% or more. A more preferable filling rate is approximately 20%. The upper limit of the filling rate is 74% when the adsorbent is packed in a close-packed structure.

In this specification, the filling rate of the adsorbent is calculated from the bulk density and the particle density of the adsorbent. Specifically, the bulk density is a numerical value obtained by dividing the mass (g) of the adsorbent filled therein by the volume (cm ³ ) of the space formed by two filters in the container. The numerical value obtained by dividing the bulk density by the particle density of the adsorbent is expressed in% as the adsorbent filling rate.

In the purifier according to the present invention, the adsorbent is preferably an oxide containing one kind of Al ₂ O ₃ . In this case, the oxide containing Al ₂ O ₃ is preferably any one oxide selected from the oxide group consisting of silica alumina and zeolite. The adsorbent is preferably heat-treated. The heat treatment of the adsorbent is preferably performed at a temperature of 200 ° C. or higher and 500 ° C. or lower.

  The purifier according to the present invention can be used when the immersion type exposure liquid to be purified is a saturated hydrocarbon compound. In particular, when the immersion type exposure liquid is 1,1′-bicyclohexyl, trans-decahydronaphthalene, or exo-tetradicyclopentadiene, it can be suitably used.

  Among the materials used for the purifier according to the present invention, preferred stainless steels include SUS304, SUS316, and the like. Moreover, PTFE, ECTFE, PFA, ETFE, PVF, PCTFE, FEP, PVDF, etc. are mentioned as a preferable fluororesin.

  Since the purifier according to the present invention has a structure in which the adsorbent is packed between two filters, the immersion type exposure liquid can be efficiently applied to the adsorbent while maintaining a constant packing density of the adsorbent. Can be contacted. Therefore, the treatment liquid stably has a transmittance of 99% or more per 1 mm of the optical path length, for example, at 193 nm (the wavelength of ArF laser light). That is, according to the purifier according to the present invention, it is possible to purify the immersion type exposure liquid once used for exposure to a level that can be sufficiently reused. If the adsorbent is not packed at a high density, contact between the adsorbent and the immersion exposure liquid may not be sufficient, and the processing liquid may not be purified to a reusable level. Also, if the adsorbent is fluid and the adsorbent packing density cannot be kept constant, the contact time between the adsorbent and the immersion type exposure liquid varies, so the transmittance value at 193 nm of the processing liquid. May vary. Such a problem does not occur with the purifier according to the present invention.

  In addition, since the adsorbent is sandwiched between two filters having a maximum pore diameter of 1 μm or more and 30 μm or less, the adsorbent hardly flows out into the processing liquid. For this reason, problems due to the presence of the adsorbent as fine particles in the immersion type exposure solution, for example, development defects in the exposure process can be suppressed.

  The purifier according to the present invention removes impurities in the immersion type exposure liquid generated by side reactions by exposure and elution of resist film components by efficient contact with the adsorbent, and is used again for exposure. Make it possible. Since the immersion exposure liquid can be used repeatedly without being discarded, it is possible to reduce the environmental load and to reduce the running cost for manufacturing the electronic device. Of course, the purifier according to the present invention can be suitably used for the initial purification of unused immersion exposure liquid.

  In a preferred embodiment of the purifier according to the present invention, at least the liquid contact part of the container is formed of any one or more materials selected from the group of materials consisting of stainless steel, fluororesin, glass, and ceramic. In the case where it is formed, the stainless steel is subjected to any one or more treatments selected from a surface treatment group consisting of an electrolytic polishing treatment and a passivation treatment. Problems such as elution of impurities into the processing solution and generation of fine particles are unlikely to occur. Also, if material components are eluted from the container itself or if fine particles are generated, the exposure liquid will be contaminated, leading to deterioration in transmittance, and further causing deterioration in resolution and development defects during exposure. However, according to the immersion type exposure liquid processed by the purifier according to the present invention, it is possible to avoid such a problem.

  In the preferred embodiment, the purifier according to the present invention has airless couplers at the inlet and outlet of the container, so that gas such as air hardly enters the container. Therefore, organic substances and moisture in the gas that has entered the container are adsorbed by the adsorbent, thereby reducing the purification capacity of the adsorbent and making the transmittance of the exposure liquid usable for exposure. The problem of difficulty can be avoided.

  In the preferred embodiment of the purifier according to the present invention, the filter is formed of any one or more materials selected from the material group consisting of stainless steel, fluororesin, and ceramic. Due to the material, it is difficult to cause problems such as elution of impurities into the processing solution and generation of fine particles. For this reason, the exposure liquid is contaminated, and resolution degradation and development defects are less likely to occur during exposure.

  In a preferred embodiment of the purifier according to the present invention, the filter is composed of a porous body, and more preferably, the maximum pore diameter of the filter is 1 μm or more and 30 μm or less. Spills are unlikely to occur. Therefore, the problem due to the presence of the adsorbent as fine particles in the immersion exposure liquid can be surely avoided.

  Since the preferred embodiment of the purifier according to the present invention is an upward flow type and includes an elastic member that presses the filter on the outlet side, the adsorbent can be used in liquid flow (during the purification process) in the upward flow. The filling rate can be surely kept within a certain range. By setting the filling rate of the adsorbent to 15% or more, it is possible to contact the adsorbent with the immersion exposure liquid more efficiently. Therefore, the treatment liquid stably and reliably has a transmittance at 193 nm of 99% or more per 1 mm of the optical path length. That is, according to a preferred aspect of the purifier according to the present invention, the immersion type exposure liquid used once for exposure is more reliably purified to a reusable level as compared with the case where it is not. I can do it. For example, if the adsorbent is developed in an upward flow without providing a resilient member that holds the filter on the outlet side, the contact between the adsorbent and the immersion exposure liquid is not sufficient, and the processing liquid is reused. Although it may not be purified to a possible level or the quality of the processing solution may vary, the purifier according to the present invention does not cause such a problem.

In the preferred embodiment of the purifier according to the present invention, the adsorbent is an oxide containing one kind of Al ₂ O ₃ , and more preferably heat-treated. Even if it is used once and impurities generated by the side reaction or elution of resist film components are included in the immersion exposure liquid, they can be efficiently removed by contact with the adsorbent. . As a result, the transmittance of the exposure liquid, for example, at 193 nm is stabilized within a certain range, and the exposure liquid can be used again for exposure.

  FIG. 1 is a cross-sectional view schematically showing one embodiment of a purifier for immersion type exposure liquid according to the present invention. A purifier 1 shown in FIG. 1 includes a container 10 mainly composed of a container body 2 and a lid 3. The container 10 includes two filters 22 and 23, and an adsorbent 20 that adsorbs and removes (purifies) impurities in the immersion exposure liquid between the two filters 22 and 23. Filled. The container body 2 is provided with an inlet 32 through which the stock solution flows, and the lid 3 is provided with an outlet 33 through which the processing liquid flows out. At the time of liquid passing (in the purification process), as indicated by an arrow in FIG. 1, the immersion type exposure liquid flows from the inlet 32, passes through the filter 22, and contacts with the adsorbent 20 to be purified. , Passes through the filter 23, and flows out from the outlet 33.

  The container body 2 has a shallow bottom portion 24, and the nozzle 12 is integrally formed on the bottom portion 24. The inlet 32 is configured by attaching the airless coupler 4 to the nozzle 12. The lid 3 has a nozzle 13. The outlet 33 is configured by attaching the airless coupler 5 to the nozzle 13. The container body 2 and the lid 3 are fixed by a clamp 14 with a packing 7 interposed therebetween.

  The filter 22 is held by holders 9 a and 9 b on the bottom 24 side of the container body 2. Since the filter 22 is fixed while providing the seal member 11 between the holders 9a and 9b, the immersion type exposure liquid flowing in from the inlet 32 cannot reach the adsorbent 20 side unless it passes through the filter 22. And there is no short circuit.

  Similarly, the filter 23 is held by holders 8 a and 8 b on the lid 3 side of the container body 2. Since the filter 23 is fixed while providing the seal member 11 between the holders 8a and 8b, the immersion exposure liquid purified by the adsorbent 20 flows out to the outlet 33 side unless it passes through the filter 23. Without short circuit. An elastic member 6 is provided between the filter 23 and the lid 3, and the elastic member 6 holds the filter 23 when liquid is passed, and the volume between the two filters 22 and 23 is kept constant. .

  Next, taking the case of the above-described purifier 1 as an example, a method for producing a purifier for immersion-type exposure liquid according to the present invention will be described. First, each member for assembling the container 10 is prepared. The container body 2 can be obtained by deep drawing press processing, welding processing, or the like using, for example, SUS304 material. The lid 3 can be obtained by, for example, deep drawing press processing, welding processing, or the like using SUS304 material, or a commercially available ferrule may be used. The holders 8a, 8b, 9a, and 9b are obtained by molding or scraping a PTFE material, for example.

  The container body 2 and the lid 3 are subjected to electrolytic polishing treatment on the liquid contact part (inner side), and the surfaces are cleaned by electrochemical dissolution. If the electrolytic polishing treatment is not performed, Fe, Cr, etc., which are raw materials of SUS304, may be eluted and fine particles may be generated. However, by performing the electrolytic polishing treatment, metal elution and generation of fine particles can be suppressed.

  As for the next member, a commercial product made of a low-elution material can be purchased. As the filters 22 and 23, for example, SUS304 porous filters having a maximum pore diameter of about 1 to 30 μm are selected. As the elastic member 6, for example, a coil spring made of SUS304 and electropolished is used. The seal member 11 employs an O-ring made of, for example, FEPM (fluororubber), and the packing 7 is made of, for example, PTFE and is prepared to fit the container body 2 and the lid 3. The airless couplers 4 and 5 are made of, for example, SUS304. The clamp 14 is selected to have a size suitable for the container body 2 and the lid 3. The clamp 14 does not come into contact with the liquid but is preferably made of SUS304 which does not rust easily.

  In conjunction with the preparation of each member, the adsorbent 20 is conditioned. As the adsorbent 20, for example, silica alumina is used. Preferably, silica alumina having a silica / alumina ratio of 3 mol / mol to 10 mol / mol is used. The adsorbent 20 is preferably heat-treated at a temperature of 200 ° C. or higher and 500 ° C. or lower. A more preferable heat treatment temperature is 250 ° C. or higher and 500 ° C. or lower. This is because if the heat treatment is performed at such a high temperature, organic substances and moisture adhering to the adsorbent 20 are sufficiently removed.

  Then, each member is assembled and the adsorbent 20 is filled. First, after inserting the holder 9a into the container body 2, the filter 22 sandwiched between the seal members 11 is incorporated, and the filter 22 is fixed by pressing with the holder 9b. Then, the heat-treated adsorbent 20 is added, and the entire container is vibrated with a vibrator or the like to increase the filling rate of the adsorbent 20. The filling rate of the adsorbent 20 is preferably 15% or more. Next, the holder 8a is inserted, the filter 23 sandwiched between the seal members 11 is incorporated, the holder 23b is pressed to temporarily fix the filter 23, and then the elastic member 6 is further incorporated. Thereafter, the lid 3 is attached with the packing 7 interposed therebetween, and the container body 2 and the lid 3 are fixed by the clamp 14. Finally, airless couplers 4 and 5 are attached to the nozzle 12 of the container body 2 and the nozzle 13 of the lid 3, respectively.

  Thus, the purifier 1 can be obtained. It is desirable that each member is sufficiently cleaned. As a cleaning method, for example, before assembling each member, it is preliminarily immersed in pure water or immersion exposure liquid for a predetermined time, sufficiently dried, and then temporarily assembled without being filled with an adsorbent, so that immersion exposure liquid is used. Can be suitably employed such as satisfying for a predetermined time or immersing in immersion exposure liquid for a predetermined time. By cleaning, it is possible to remove contaminants (eluting substances) present on the liquid contact part (surface) of the container. The assembled purifier 1 is preferably stored in a state in which an inert gas such as nitrogen is supplied and air is completely excluded. Furthermore, it is more preferable that the liquid for immersion exposure is passed to remove the inert gas.

  Next, the use of the immersion-type exposure liquid purifier according to the present invention will be described by taking the case of the above-described purifier 1 as an example. The purifier 1 can be used as an initial purification means of the immersion type exposure liquid or as a means for refining the immersion type exposure liquid used at least once for exposure to be used for exposure again. I can do it. In the latter case, if the immersion exposure liquid can achieve a transmittance of 99% or more per mm at a wavelength of 193 nm, the transmittance at a wavelength of 193 nm is 99 per mm when used at least once for exposure. It is possible to recover the transmittance at a wavelength of 193 nm to 99% or more per mm of the immersion type exposure liquid which is less than%.

The exposure is exposure performed through a liquid filled between the optical element of the projection optical means and the substrate, and the immersion exposure liquid is the liquid used for the exposure. In the purifier 1, the object to be purified may be an immersion type exposure liquid, and a specific method of exposure using the immersion type exposure liquid and exposure using the purified immersion type exposure liquid. The exposure light (light source) is not limited. The exposure light (light source) may be ArF laser light (193 nm), KrF laser light (248 nm), F ₂ laser light (157 nm), etc., and an ultraviolet emission line (g line, h) emitted from a mercury lamp. Line, i-line).

  As the immersion type exposure liquid to be purified, a saturated hydrocarbon compound can be preferably exemplified. This saturated hydrocarbon compound preferably has a radiation transmittance of 90% or more at an optical path length of 1 mm of ArF laser light having a wavelength of 193 nm. More preferably 95% or more, still more preferably 97% or more, and particularly preferably 99% or more. Specific examples of the saturated hydrocarbon compound include 1,1'-bicyclohexyl, decalin (trans-decahydronaphthalene), and exo-tetradicyclopentadiene. These are liquids that can realize a transmittance of 99% or more at a wavelength of 193 nm and a refractive index of 1.64 or more (when the temperature is 23 ° C.) and a thickness of 1 mm.

  The purifier 1 is used by being incorporated into a batch processing system or a circulation processing system when used as an initial purification means of the immersion type exposure liquid. In the case of refining the immersion type exposure liquid used at least once for the exposure, it can be used by being incorporated in a circulation system of the exposure liquid in the immersion type exposure apparatus. In any case, at the time of the purification process of the immersion type exposure liquid, the inlet 32 is located on the lower side, the outlet 33 is located on the upper side, and the immersion type exposure liquid is adsorbed upward in the container 10. It is used in contact with the agent 20.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention should not be construed as being limited to these embodiments, and should be understood by those skilled in the art without departing from the scope of the present invention. Various changes, modifications and improvements can be made based on this. The drawings used in the description represent preferred embodiments of the present invention, but the present invention is not limited by the modes shown in the drawings or the information shown in the drawings. In practicing or verifying the present invention, means similar to or equivalent to those described in the present specification can be applied, but preferred means are those described below. For example, zeolite or the like can be used as the adsorbent 20 instead of silica alumina, and ceramic porous filters can be selected as the filters 22 and 23. The container body 2 may be formed by molding, for example, PVDF material, etc., and the lid 3 can adopt a flange type, and the lid 3 container body 2 and the lid 3 are fastened with bolts and nuts or clips. It is also possible. Further, the elastic member 6 may use a leaf spring. Further, the adsorbent 20 is filled under pressure, or after the adsorbent 20 is dispersed in the immersion exposure liquid and filled into the column in a slurry state, the above-described immersion exposure is performed using a pump or the like. A method of filling the liquid by feeding under pressure may be used.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

  The transmittance of trans-decahydronaphthalene, which is an immersion type exposure liquid, at a wavelength of 193 nm was 99.1% / mm, and the number of fine particles of 0.15 μm or more was 16/10 ml. This liquid (trans-decahydronaphthalene before passing through) is defined as EK-1.

  (Example 1) Using a purifier having the structure shown in FIG. 1, without passing through the adsorbent, EK-1 was passed through the purifier, and the liquid transmittance at a wavelength of 193 nm after passing through, and The number of fine particles of 0.15 μm or more contained in the liquid was measured. The operation of passing EK-1 through the purifier was performed in a nitrogen atmosphere, and the flow rate was 100 ml / min. As a member constituting the purifier, a container body and lid made of SUS304 subjected to electrolytic polishing treatment, a packing made of PTFE, an O-ring made of fluoro rubber as a sealing member, and made of SUS304 subjected to electrolytic polishing treatment as a resilient member. Two filters of SUS made of SUS and having a maximum pore diameter of 2 μm were used.

  The transmittance of the liquid after passing through at a wavelength of 193 nm was 99.1% / mm, and the number of fine particles of 0.15 μm or more was 10/10 ml.

  (Example 2) The same operation as in Example 1 was carried out except that a purifier was filled with zeolite (F-9, average particle size: 4 µm) as an adsorbent. The transmittance of the liquid after passing through at a wavelength of 193 nm was 99.1% / mm, and the number of fine particles of 0.15 μm or more was 13/10 ml.

  (Comparative Example 1) The same operation as in Example 1 was performed except that an ODM ring made of EPDM was used as a sealing member. The transmittance of the liquid after passing through at a wavelength of 193 nm was 91.1% / mm, and the number of fine particles of 0.15 μm or more was 406/10 ml.

  (Comparative Example 2) The same operation as in Example 1 was conducted except that a purifier was filled with zeolite (manufactured by Tosoh Corporation, F-9, average particle size: 4 μm) and a filter having a maximum pore size of 50 μm was used. did. The transmittance of the liquid after passing through at a wavelength of 193 nm was 99.1% / mm, and the number of fine particles of 0.15 μm or more was 310/10 ml.

  (Consideration 1) From Example 1 and Comparative Example 1, when EPDM was used for the liquid contact part of the container, the liquid permeability after passing through the purifier decreased and the number of fine particles increased. Further, from Example 2 and Comparative Example 2, when the maximum pore size of the filter was 50 μm, the number of fine particles in the liquid after passing through the purifier was increased.

When trans-decahydronaphthalene, which is an immersion type exposure liquid, was irradiated with ArF laser light at 150 J / cm ² and the transmittance at 193 nm (transmission after irradiation) was measured, it was 96.8% / mm. This liquid is designated as EK-2. The transmittance at a wavelength of 193 nm before irradiation was 99.1% / mm.

When exo-tetradicyclopentadiene, which is an immersion type exposure liquid, was irradiated with ArF laser light at 600 J / cm ² and measured for transmittance (transmittance after irradiation) at a wavelength of 193 nm, it was 91.6%. / Mm. This liquid is designated as EK-3. The transmittance at a wavelength of 193 nm before irradiation was 99.7% / mm.

When 1,1′-bicyclohexyl, which is an immersion type exposure liquid, was irradiated with ArF laser light at 800 J / cm ² and the transmittance (transmittance after irradiation) at a wavelength of 193 nm was measured, 96.4 was obtained. % / Mm. This liquid is designated as EK-4. The transmittance at a wavelength of 193 nm before irradiation was 99.5% / mm.

  Example 3 Using a purifier having the structure shown in FIG. 1, silica alumina (manufactured by JGC Chemical Co., N633L) as an adsorbent is filled at a filling rate of 20%, and EK-2 is placed on the purifier. The liquid was passed in countercurrent, and the liquid transmittance at a wavelength of 193 nm after the liquid flow was measured. The operation of passing EK-2 through the purifier was performed in a nitrogen atmosphere, and the flow rate was 100 ml / min. As a member constituting the purifier, a container body and lid made of SUS304 subjected to electrolytic polishing treatment, a packing made of PTFE, an O-ring made of fluoro rubber as a sealing member, and made of SUS304 subjected to electrolytic polishing treatment as a resilient member. Two filters of SUS made of SUS and having a maximum pore diameter of 10 μm were used.

  The transmittance of the liquid after passing through the purifier at a wavelength of 193 nm was 99.1% / mm.

  (Example 4) The same operation as in Example 3 was performed except that the immersion type exposure liquid to be passed was changed to EK-3. The transmittance of the liquid after passing through at a wavelength of 193 nm was 99.7% / mm.

  (Example 5) The same operation as in Example 3 was performed except that the immersion type exposure liquid to be passed was changed to EK-4. The transmittance of the liquid after passing through at a wavelength of 193 nm was 99.5% / mm.

  (Comparative Example 3) The same operation as in Example 3 was performed except that the filling rate of the adsorbent was 14%. The transmittance of the liquid after passing EK-2 at a wavelength of 193 nm was 98.7% / mm.

  (Comparative Example 4) The same operation as in Example 3 was performed except that the type of adsorbent was silica gel (manufactured by Wako Pure Chemicals, C-200). The transmittance of the liquid after passing EK-2 at a wavelength of 193 nm was 98.5% / mm.

  (Comparative Example 5) The operation was performed in the same manner as in Example 3 except that the elastic member for pressing one of the two filters was removed. The transmittance of the liquid after passing EK-2 at a wavelength of 193 nm was 98.8% / mm. When the filling rate of the filler was measured after passing through, it was 13%.

  (Comparative Example 6) The operation was performed in the same manner as in Example 3 except that the liquid flow direction was changed to the downward direction (downward flow). The transmittance of the liquid after passing EK-2 at a wavelength of 193 nm was 98.8% / mm.

  (Consideration 2) From Examples 3 to 5 and Comparative Example 3, it was possible to remove impurities generated in the immersion type exposure liquid by exposure when the filling rate was 15% or more.

From Examples 3 to 5 and Comparative Example 4, it was possible to remove impurities generated in the immersion type exposure liquid by exposure by using an oxide containing Al ₂ O ₃ as a filler.

  From Examples 3 to 5 and Comparative Example 5, when the elastic member that presses one of the two filters is removed, the filling rate changes during liquid passing, so that the adsorbent and the liquid are in sufficient contact with each other. The impurities generated by exposure could not be completely removed.

  From Examples 3 to 5 and Comparative Example 6, it was possible to efficiently and completely remove impurities generated by exposure by setting the liquid flow path direction upward.

  [Transmissivity] In a glove box with a nitrogen atmosphere controlled to 0.5 ppm or less, each liquid was sampled in a cell with an optical path length of 1 cm and 2 cm with a polytetrafluoroethylene lid, and a V7100 manufactured by JASCO Corporation was used. The absorbance was measured using the cell containing each liquid as a sample and air as a reference, and the difference between the two was defined as the absorbance per 1 cm. Based on this value, the transmittance per mm was calculated according to Lambert Beer's law. The transmittance value shown in each example is a value obtained by correcting the reflection of the cell by calculation.

  The immersion type exposure liquid purifier according to the present invention includes an initial stage of the liquid applied to the immersion type exposure means for performing exposure through the liquid filled between the optical element of the projection optical means and the substrate. It can be used as a means for purification and purification for reuse. In particular, it can be suitably used when the liquid is an alicyclic saturated hydrocarbon compound.

It is sectional drawing which shows one Embodiment of the refiner | purifier of the immersion type exposure liquid which concerns on this invention.

Explanation of symbols

1: Purifier, 2: Container body, 3: Lid, 4, 5: Airless coupler, 6: Elastic member, 7: Packing, 8a, 8b: Holder, 9a, 9b: Holder, 10: Container, 11: Seal Member, 12, 13: nozzle, 14: clamp, 20: adsorbent, 22, 23: filter, 24: bottom, 32: inlet, 33: outlet.

Claims (16)

  An immersion type exposure liquid comprising: a container having an inlet through which a stock solution flows and an outlet through which a processing solution flows out; two filters provided in the container; and an adsorbent filled between the two filters. Purifier.   2. The purifier according to claim 1, wherein at least the liquid contact portion of the container is formed of any one or more materials selected from a material group consisting of stainless steel, fluororesin, glass, and ceramic.   The purifier according to claim 2, wherein the stainless steel is subjected to any one or more treatments selected from a surface treatment group consisting of an electrolytic polishing treatment and a passivation treatment.   The purifier according to any one of claims 1 to 3, further comprising an airless coupler at an inlet and an outlet of the container.   The purifier according to any one of claims 1 to 4, wherein the filter is formed of any one or more materials selected from a material group consisting of stainless steel, fluororesin, and ceramic.   The said filter is a refiner as described in any one of Claims 1-5 comprised with a porous body.   The purifier according to claim 6, wherein the maximum pore diameter of the filter is 1 μm or more and 30 μm or less.   During the refining process of the immersion type exposure liquid, the inlet is positioned on the lower side, the outlet is positioned on the upper side, and the immersion type exposure liquid contacts the adsorbent in an upward flow in the container. The purifier according to any one of claims 1 to 7.   The purifier according to claim 8, further comprising an elastic member that holds one of the two filters on the outlet side located on the upper side.   The purifier according to any one of claims 1 to 9, wherein a filling rate of the adsorbent is 15% or more. The adsorbent purifier according to any one of claims 1 to 10 is an oxide containing one of Al ₂ O _3. The purifier according to claim 11, wherein the oxide containing Al ₂ O ₃ is any one oxide selected from an oxide group consisting of silica alumina and zeolite.   The purifier according to any one of claims 1 to 12, wherein the immersion exposure liquid to be purified is a saturated hydrocarbon compound.   The purifier according to claim 13, wherein the immersion type exposure liquid is 1,1′-bicyclohexyl.   The purifier according to claim 13, wherein the immersion type exposure liquid is trans-decahydronaphthalene.   The purifier according to claim 13, wherein the immersion type exposure liquid is exo-tetradicyclopentadiene.

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