JP5663996B2 - Manufacturing method of storage case for synthetic quartz glass substrate or photomask blank for photomask - Google Patents

Description

  The present invention relates to a method for producing a storage case for a synthetic quartz glass substrate for photomask or a photomask blank.

  As semiconductor devices are highly integrated, there is an increasing demand for miniaturization in the photolithography process. A photomask used for photolithography is manufactured by forming a light-shielding thin film made of chromium or the like on a synthetic quartz glass substrate, further applying a resist, and then performing processes such as drawing, developing, and etching with an electron beam or the like. . A state in which a light shielding film is formed on a synthetic quartz glass substrate before drawing is called a photomask blank.

  With miniaturization of wiring patterns in semiconductor devices, there is a need for a technique that does not cause film formation unevenness or application unevenness in the formation of a light shielding film on a synthetic quartz glass substrate and the application of a resist on a photomask blank. From such a demand, a very high cleanliness is also required for a synthetic quartz glass substrate and a photomask blank (hereinafter referred to as “substrate etc.” if necessary). For this reason, the storage of the substrate or the like is required to suppress foreign matters and the like from adhering to the substrate and maintain the cleanliness as high as possible.

  By the way, a storage case for a substrate or the like is formed, for example, by melting and bonding a resin plate such as polyacrylonitrile with an organic solvent such as acetonitrile, that is, by welding. And it becomes a problem that the chemical component of the outgas derived from the resin material of the storage case is adsorbed on the surface of the substrate or the like stored therein. The amount of outgas from the bonded portion of the welded resin plate is particularly large.

  As proposals for preventing the influence of chemical component adsorption, Patent Documents 1 to 3 disclose a case equipped with a filter containing activated carbon and a mechanism of the filter. According to these, by eliminating the pressure difference inside and outside the case, it is possible to prevent contamination from the external environment due to the pressure difference generated during transportation. On the other hand, in patent document 4, activated carbon is arrange | positioned in the storage case in order to remove organic substance. Patent Document 5 discloses a metal storage case that does not generate outgas.

JP 2004-153221 A JP 2004-179449 A JP 2004-193272 A JP 2009-55005 A JP 2009-179531 A

  However, the techniques disclosed in Patent Documents 1 to 3 are insufficient as a countermeasure against outgas inside the storage case due to the material of the storage case. Moreover, in patent document 4, the synthetic resin type nonwoven fabric is used for the packaging material of activated carbon. Since the synthetic resin-based nonwoven fabric has a low gas permeability, the technology disclosed in Patent Document 4 cannot sufficiently adsorb chemical components. Also, fine dust is generated from the activated carbon and the synthetic resin nonwoven fabric which is the packaging material. If fine foreign matter such as dust adheres to the surface of a substrate or the like during storage, it adheres and cannot be removed by cleaning. On the other hand, in the metal storage case disclosed in Patent Document 5, no outgas is generated, but it is difficult to visually determine whether the storage case is contaminated because of its metallic luster, and the storage case is overlooked. Cheap. When a substrate or the like is stored in a contaminated storage case, the stored substrate or the like may be contaminated. Therefore, a storage case made of a synthetic resin that can easily determine the contamination state visually is preferable to a metal case.

  Therefore, the present invention has been made to solve the above problems, and is a method for manufacturing a storage case for a synthetic quartz glass substrate for a photomask and a photomask blank, wherein a case is formed by joining synthetic resin members. An object of the present invention is to provide a method for manufacturing a storage case that is less likely to generate an outgas component that may be adsorbed to a substrate or the like.

According to state-like of the present invention, there is provided a method for producing a storage case of the synthetic quartz glass substrate or the photomask blank for a photomask, comprising: providing a casing formed by joining the synthetic resin member, gel-like It established the adsorbent activated carbon is dispersed into the medium within the case, seen containing a be left for a predetermined time, and to take out the adsorbent from the case, that washing the case where the adsorbent is removed When the adsorbent is placed and left in the case, the adsorbent is brought into contact with a joint portion of the synthetic resin member in the case, and the adsorbent is washed with a cleaning agent so that the adsorbent is Provided is a method for producing a storage case for a synthetic quartz glass substrate for photomask or a photomask blank in which the case is cleaned while being removed from the case.

  In the method for manufacturing a storage case according to the aspect of the present invention, before the substrate is stored in the storage case, the outgas component derived from the synthetic resin case is adsorbed and removed using an adsorbent in which activated carbon is dispersed in a gel-like medium. In this case, the adsorption of the outgas component to the substrate to be stored can be suppressed. As a result, the manufactured storage case can store the substrate and the like in a clean state, and can prevent uneven formation of the light-shielding film and resist application on the substrate and the like. In addition, since the adsorbent in which activated carbon is dispersed in a gel-like medium generates little dust, it can prevent adhesion of minute foreign substances such as dust to the substrate.

It is a flowchart explaining the manufacturing method of the storage case of the synthetic quartz glass substrate for photomasks of a reference form and embodiment. It is the schematic of the case where the adsorbent was installed in the inside used by the reference form. (A) And (b) is sectional drawing of the case where the adsorbent was installed in the inside used by the reference form. (C) is a top view of the case main body used in the reference embodiment and having an adsorbent installed therein. It is a perspective view of the synthetic quartz glass substrate for photomasks used in a reference form, and its storage case. Used in implementation form, it is a schematic view of a case that internal to the adsorbent is installed. (A) and (b) are used in the implementation form, a cross-sectional view of a case inside the adsorbent is installed. (C) was used in the implementation form, a top view of the case body inside the adsorbent is installed. It is a figure which shows the relationship between the time which passed since the case preparation in the reference example , and the outgas generation amount (concentration) inside a case.

[ Reference form]
As a reference embodiment of the present invention, a manufacturing method (preparation method) of a storage case for a synthetic quartz glass substrate for a photomask will be described with reference to FIG. The synthetic quartz glass substrate for a photomask is a substrate for forming a photomask serving as a master for photolithography. And what formed the light shielding film which consists of chromium etc. on the synthetic quartz glass substrate for photomasks is a photomask blank. In this reference embodiment, a method for manufacturing a storage case for a synthetic quartz glass substrate for photomask will be described. However, a storage case for a photomask blank can also be manufactured by the same method.

First, a case 1 for storing a synthetic quartz glass substrate 10 for photomask (hereinafter referred to as “substrate 10” if necessary) is prepared (step 1). As shown in FIGS. 2 to 4, the case 1 of the present reference embodiment, for example, has a rectangular parallelepiped box shape whose upper surface is open, box-shaped case body for housing the substrate 10 of rectangular shape in the interior 2 And a lid 3 that covers the opening of the case body 2 and is detachably attached to the case body 2. The case body 2 includes a rectangular bottom plate 21, a pair of first side walls 22 that are coupled to the long side of the bottom plate 21 and opposed to each other, and a pair of second side walls 23 that are coupled to the short side of the bottom plate 21 and opposed to each other. Become. The second side wall 23 connects a pair of first side walls 22 facing each other. The case 1 is a vertical case that stores the substrate 10 in a substantially vertical position. Regarding the bottom plate 21, the first side wall 22, and the second side wall 23, the surfaces forming the inside of the case 1 are referred to as “inner surfaces”, and the surfaces forming the outer side of the case 1 are referred to as “outer surfaces”. When the substrate 10 is stored, the inner surface of the first side wall 22 faces the surface of the substrate 10. On the other hand, the inner surface of the second side wall 23 faces the end surface of the substrate 10 and holds the substrate 10 via a support member 27 described later.

  On the outer surfaces of the first and second side walls 22 and 23, a collar 24 is provided so as to protrude. The flange 24 is connected and provided so as to go around the outside of the case body 2 over the four outer surfaces of the first and second side walls 22 and 23. A portion of the case body 2 located on the upper surface side (opening side) from the flange 24 is referred to as a fitting portion 25.

  The lid 3 is a rectangular parallelepiped box having an open bottom surface, and includes an upper plate 31 and two pairs of lid side walls 32 and 33 that are connected to the upper plate 31 and face each other. Regarding the upper plate 31 and the lid side walls 32 and 33, the surfaces forming the inner side of the case 1 are referred to as “inner surfaces”, and the surfaces forming the outer side of the case 1 are referred to as “outer surfaces”. Lower end portions (end portions on the opening side) of the outer surfaces of the lid side walls 32 and 33 protrude outward and form a flange 34. The flange 34 is provided so as to make a round around the outside of the lid 3 over the four outer surfaces of the lid side walls 32 and 33.

  As shown in FIG. 3, the lid 3 is attached to the case body 2 by fitting the fitting portion 25 of the case body 2 into the opening on the lower surface thereof. At this time, the reeds 24 and 34 of the case body 2 and the lid 3 are in contact with each other. In order to improve the sealing performance of the case 1, the case main body 2 has an annular elastic member 26 along the inner edge of the flange 24.

  Furthermore, a support member 27 that supports the substrate 10 when the substrate 10 is stored is provided on the inner surfaces of the second side wall 23 and the bottom plate 21. The support member 27 is a rod-shaped member having a concave portion at the center, and extends along the longitudinal direction of the second side wall 23 and the bottom plate 21, and the central concave portion also extends along the extending direction of the support member 27. That is, the cross section perpendicular to the extending direction of the support member 27 is concave, and the substrate 10 is supported by sandwiching the end of the substrate 10 in the recess. A tube 37 is provided on the inner surface of the upper plate 31 of the lid 3, and the tube 37 extends along the longitudinal direction of the upper plate 31. When the lid 3 is attached to the case body 2, the tube 37 contacts the upper end surface (end surface on the lid side) of the substrate 10. In this way, the substrate 10 is supported by the tube 37 on the lid side and the support body 27 on the case body side.

  Examples of the material constituting the case body 2, the lid 3, the support 27, and the tube 37 include polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyacrylonitrile (PAN), and polyether ether ketone (PEEK). , Polyurethane (PU), polystyrene (PS), polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE), polymethacrylonitrile (PMAN), polymethyl acrylate (PMA), polyethyl methacrylate (PEMA), etc. Or a synthetic resin composed of these copolymers. Of these, polycarbonate (PC) or polyacrylonitrile (PAN) is preferable as the material of the case body 2 and the lid 3 because it has high strength and is strong against impact. The material of the support 27 and the tube 37 is high density polyethylene. (HDPE) or polytetrafluoroethylene (PTFE) is preferred because it emits less chemical component gases. As the elastic member 26, for example, a polyolefin elastomer or a polyester elastomer can be used.

The case 1 is formed by joining a plurality of plate-shaped synthetic resin members using a solvent, an adhesive, or the like by a known method. For example, a resin plate such as polyacrylonitrile is melted with an organic solvent such as acetonitrile and welded. In the case body 2 of this preferred embodiment, the bottom plate 21, to prepare a case main body 2 by welding using a five organic solvent parts made of a resin plate of the pair of first side wall 22 and a pair second sidewall 23 . Similarly, the lid 3 is manufactured by welding parts made of five resin plates, that is, the upper plate 31 and the two pairs of lid side walls 32 and 33 with an organic solvent. Although the solvent used for welding is appropriately selected according to the material of the case, for example, acetonitrile, dichloromethane, acetone or the like can be used.

Next, the adsorbent 4 in which activated carbon is dispersed in a gel-like medium is installed in the prepared case 1, and left for a predetermined time (step S2). In this reference embodiment, 16 commercially available adsorbents 4 housed in a plastic case were installed on the inner surface of the bottom plate 21 of the case body 2 as shown in FIGS.

As described above, the case for storing the substrate is formed of a synthetic resin, and the plasticizer, the solvent used for welding, or the adhesive component contained therein is generated in the case as an outgas component. In particular, immediately after the case is produced, a large amount of outgas of the organic solvent and the dissolved synthetic resin component is generated from the joint portion. If the surface of the synthetic quartz glass substrate is contaminated by adsorption of outgas components, a light shielding film cannot be uniformly formed on the surface. Similarly, if the surface of the photomask blank is contaminated with an outgas component, the resist film cannot be applied uniformly. Since the outgas component adsorbed on the surface of the substrate or the like cannot be removed by cleaning, it is important to prevent the adsorption to the surface. In this reference embodiment, the outgassed before housing the substrate 10 in the case 1 is adsorbed and removed, it is possible to prevent adsorption to the substrate 10 of the outgas components. As a result, the substrate 10 can be stored in a clean state, and uneven formation of the light shielding film on the substrate 10 and uneven application of the resist can be prevented.

Furthermore, since the adsorbent 4 used in the present invention has activated carbon dispersed in a gel-like medium, dust generation from the activated carbon can be prevented. There is no need for activated carbon packaging material, and there is no worry about dust generation from the packaging material. Furthermore, it turned out that the adsorbent 4 of this reference form has the outgas adsorption | suction performance higher than the adsorbent which packaged the activated carbon with the synthetic resin type nonwoven fabric. This is because, compared with the activated carbon granular activated carbon and fibrous used in the conventional adsorbent, considered towards the powdered activated carbon used for the adsorbent is due to the large surface area.

The gel medium of this preferred embodiment as an adsorbent 4 activated carbon is dispersed may be used an adsorbent that is commercially available, adsorbent 4 may have a configuration that is housed in a plastic case such as . The gel-like medium is preferably a water-based gel. As the gelling agent for forming the gel, carrageenan, gellan gum, agar, gelatin, guar gum, pectin, locust bean gum, xanthan gum, sodium alginate, cellulose derivatives and the like are known. Is used. Further, as various additives in the gel, for example, glycols such as ethylene glycol and propylene glycol as a dispersing agent, alkali metal salts such as sodium chloride as a gel reinforcing agent, and alkaline earth metal salts such as calcium chloride Further, a quaternary ammonium salt such as chloroisothiazole as a preservative, a benzoate such as sodium benzoate, and a benzophenone compound as an ultraviolet absorber may be blended as necessary.

Adsorbent 4 for use in the present reference embodiment, while it is left in the casing 1, or not even emit any component, or it is preferable to substrate 10 is a adsorbent that releases only components that do not contaminate. Examples of components that do not contaminate the substrate 10 include water or alcohols such as ethanol, methanol, and isopropyl alcohol. This is to prevent components released from the adsorbent from remaining in the case 1 and thereby contaminating the substrate 10. Therefore, it is preferable that the adsorbent 4 of the present reference embodiment does not include a component that contaminates the substrate 10.

  The method of installing the adsorbent 4 is not particularly limited, but when using an adsorbent configured to be stored in a plastic case, the adsorbent 4 may be installed in the case 1 while being stored in the plastic case. In this case, since the gel-like medium does not directly contact the inner surface of the case 1, the medium component can be prevented from adhering to the case 1. On the other hand, the adsorbent 4 may be installed directly in the case 1. In this case, there is a possibility that the medium component adheres to the inner surface of the case 1, but it can be removed by a later-described cleaning process. Moreover, you may install the adsorbent 4 using a jig | tool.

In the present reference embodiment has used 16 adsorbent 4, the installation number may be appropriately selected depending on the relationship of volume and gas adsorption capacity of the absorbent 4 of the case 1. The installation location of the adsorbent 4 may be inside the case 1, for example, may be on the bottom plate 21 of the case main body 2, or an installation location is provided in the case in advance and installed at the installation location. May be.

  The time for which the adsorbent 4 is left in the case 1 is arbitrarily determined based on the size, material, production method and the like of the outgas due to the case size and amount, the outgas adsorption performance, amount, and number of the adsorbent. Although it can be set, it is preferably 3 weeks or longer. By leaving the adsorbent 4 in the case 1 for 3 weeks or more, the outgas in the case is sufficiently adsorbed and removed, and thereafter the adsorption of the outgas to the surface of the substrate 10 stored in the storage case is suppressed. The adsorbent 4 is preferably left in the case 1 in a sealed state. For example, after the adsorbent 4 is installed on the bottom plate 21 of the case main body 2, the case 3 is sealed by attaching the lid 3 to the case main body 2, and then left for a predetermined time. By making the case 1 hermetically sealed, outgas generated in the case 1 can be effectively adsorbed.

  After the adsorbent 4 in which activated carbon is dispersed in a gel-like medium is left in the case 1 for a predetermined time, the adsorbent 4 is taken out from the case 1 (step S3). The method for taking out the adsorbent 4 from the case 1 is not particularly limited, and a jig or the like may be used as necessary. The amount of outgas generated from the joint of case 1 is the largest immediately after the case is made, and then gradually decreases. Therefore, if the adsorbent 1 is left in the case for a predetermined time and the outgas is removed before the substrate 10 is stored in the case, the outgas in the case will remain even if the adsorbent 4 is removed from the case 1 thereafter. Adsorption to 10 can be suppressed.

Thus, in this preferred embodiment, prior to receiving the substrate 10 to the case 1, since the case 10 is taken out of the adsorbent 4, it is not possible to store the substrate 10 in a state that established the adsorbent 4 in the case 1 . Therefore, it is possible to suppress the contaminants derived from the adsorbent 4 from adhering to the substrate 10. For example, it is conceivable that the substrate 10 is transported while being stored in the case 1, and in such a case, if the adsorbent 4 is present in the case, a contaminant may be generated from the adsorbent 4 due to vibration caused by transport. However, there is no such worry in this reference embodiment. Further, since the adsorbent 4 does not exist in the case 1 when the substrate 10 is transported, the adsorbent 4 does not need to be fixed inside the case 1, and may be left on the bottom plate, for example.

  After removing the adsorbent 4 from the case 1, the case 1 is washed (step S4). Thereby, even if the foreign material which invaded the case 1 in the installation and removal of the adsorbent 4 or the contaminant derived from the adsorbent 4 is generated, these can be removed and the inside of the case can be made clean.

Through the above steps, a storage case for a synthetic quartz glass substrate for a photomask is manufactured. Storage case of the present reference embodiment, outgas components hardly occurs that could adsorb to the substrate or the like, less dust generation from the adsorbent. Therefore, the substrate or the like can be stored in a clean state.

[Implementation form]
As implementation mode, when installing and left adsorbent into the case (step S2), and brought into contact with the joint portion of the synthetic resin member in the adsorbent casing, by flushing the cleaning agent said adsorbent, wherein The manufacturing method (preparation method) of the storage case will be described while the adsorbent is removed from the case (step S3) and the case is washed (step S4). That is, in the present embodiment, the adsorbent is removed from the case (step S3) and the case is washed (step S4) at the same time. In the following description, the same reference numerals are used for the same members as those in the reference embodiment.

First, similarly to the reference embodiment, a case 1 in which a synthetic resin member is joined is prepared (step S1). Next, as shown in FIG. 5 and FIG. 6, the adsorbent 5 in which activated carbon is dispersed in a gel-like medium is brought into direct contact with the welding location inside the case 1. Specifically, the bottom plate 21, the pair of first side walls 22, and the pair of second side walls 23 in the case main body 2, the welding positions of the upper plate 31, the pair of lid side walls 32 and 33 in the lid 3. It is. The gel-like adsorbent 5 is brought into close contact with a part or all of these welds by coating or the like. Thereafter, the lid 3 is attached to the case body 2, and the case 1 is left in a sealed state for a predetermined time (step S2). A large amount of outgas of the organic solvent used for welding and the dissolved synthetic resin component is generated from the joint portion of the case. In this embodiment, since the adsorbent 5 is brought into direct contact with the welded portion, outgas can be adsorbed efficiently.

  After the adsorbent 5 is left in the case 1 for a predetermined time, the adsorbent 5 is removed from the case 1 by washing away with the cleaning agent (step S3). By this operation, the case 1 can be simultaneously cleaned with the cleaning agent (step S4). As the cleaning agent, various solvents that can drain the adsorbent 5 from the case 1 and can clean the case 1 can be used, but alcohols such as ethanol, methanol, isopropyl alcohol are preferable, Ethanol is preferred.

Through the above steps, a storage case for a synthetic quartz glass substrate for a photomask is manufactured. The storage case of the present embodiment can achieve the same effects as the storage case of the reference form. Further, in the present embodiment, since the adsorbent 5 can be removed from the case 1 (step S3) and the case 1 can be cleaned (step S4) simultaneously, the manufacturing process can be simplified and the manufacturing time can be shortened. it can.

The case 1 described in reference embodiment及BiMinoru facilities embodiment, the short side of 300mm or more, it is possible to house the substrate long side 400mm or more of the rectangular plate-like body. For example, the substrate size is short side (mm) × long side (mm), 330 × 450, 370 × 450, 420 × 520, 420 × 530, 430 × 530, 440 × 520, 500 × 750, 520 × 610, 520 × 800, 620 × 720, 650 × 750, 650 × 800, 700 × 800, 800 × 920, 700 × 1,100, 800 × 960, 830 × 960, 850 × 1,000, 830 × 1,196, 850 These are synthetic quartz glass substrates for photomasks such as × 1,200, 830 × 1,396, 810 × 1,380, 850 × 1,400, 1,220 × 1,400, 1,620 × 1,780.

Note that in reference embodiment及BiMinoru facilities embodiment describes vertical case Keep substantially standing in a vertical state of the substrate to the ground, the case is substantially horizontal state substrate relative to the ground within the casing It may be a horizontal case that is laid down and stored. Further, in the reference embodiment及BiMinoru facilities embodiment has been described for the case stores one substrate, the case may be in two or more of a plurality of substrates stored case.

Hereinafter, the present invention will be specifically described with reference examples and comparative examples, but the present invention is not limited to the following reference examples .

[ Reference example ]
First, as a case 1 shown in FIGS. 2 to 4, a rectangular quartz plate-shaped synthetic quartz glass substrate 10 for a photomask having a size of 1620 mm × 1780 mm × 17 mm is stored in a state of being substantially perpendicular to the ground. A vertical case was prepared. The size of the internal space of the case 1 that accommodates the substrate 10 was about 1800 mm × about 2000 mm × about 230 mm. The case main body 2 and the lid 3 of the case 1 of this reference example were formed by welding a polyacrylonitrile (PAN) resin plate with acetonitrile. The material of the support member 27 and the tube 37 was polytetrafluoroethylene (PTFE), and the material of the elastic member 26 was a polyolefin elastomer.

Was then 16 established the adsorbent 4 inside the case 1. The adsorbent 4 used was a deodorizing charcoal kitchen manufactured by Este Co., Ltd. (55 g) having a configuration in which an adsorbent in which activated carbon and Bincho charcoal were dispersed in a gel-like medium was placed in a plastic container. The adsorbent is on the inner surface of the bottom plate 21 and has four places on the intersections of the lines that divide the long side and the short side of the bottom plate 21 into three equal parts, and a total of 16 places around the intersection. Arranged. A lid 3 was attached to the case body 2 and the case 1 was sealed, and then left for 3 weeks. Three weeks later, the adsorbent was taken out from Case 1, and then Case 1 was washed and dried.

  The synthetic quartz glass substrate for photomask 10 that had been subjected to polishing, cleaning, and appearance inspection was stored in a storage case manufactured by performing the above operations. Storage work was performed in a clean room. The synthetic quartz glass substrate for photomask 10 was stored in the storage case 1 and stored for 3 months in a non-clean room environment at a temperature of 20 to 30 degrees and a humidity of 40 to 60%.

  After storage for 3 months, the substrate 10 was taken out from the storage case 1. The substrate 10 taken out had no deposits such as dust. The substrate 10 was cleaned and a CrO film was formed in accordance with a predetermined procedure to produce a photomask blank. A CrO film without film formation unevenness could be formed on the substrate 10.

[Change in outgas generation over time]
With respect to the amount of outgas generation (concentration) inside Case 1, the temporal change from the case production was evaluated. In order to perform this evaluation, a test case made of the same material as the above-described storage case 1 used in this reference example was produced. From the preparation of the test case to 60 days later, the gas in the test case was sampled five times on different days. The amount of acetonitrile in the sampled gas was measured by thermal desorption-GC / MS (gas chromatography / mass spectrometry) to determine the outgas generation amount. The relationship between the elapsed days and the amount of acetonitrile generated in the test case is shown in FIG.

[Comparative Example 1]
A storage case was manufactured in the same manner as in the reference example except that the adsorbent 4 was not installed inside the case 1. A synthetic quartz glass substrate for photomask was stored in the manufactured storage case in the same manner as in the reference example .

After storage, the substrate 1 was taken out from the storage case, and a photomask blank was produced in the same manner as in the reference example . Film formation unevenness occurred in the formed CrO film.

[Comparative Example 2]
A storage case was produced in the same manner as in the reference example , except that a fibrous activated carbon wrapped with a synthetic resin nonwoven fabric was used as the adsorbent. A synthetic quartz glass substrate for photomask was stored in the manufactured storage case in the same manner as in the reference example .

  After storage, the substrate was removed from the case. A lot of minute foreign matters such as dust adhered to the substrate taken out. Therefore, in this comparative example, production of a photomask blank from this substrate was stopped. It is thought that the dust adhering to the substrate is derived from an adsorbent in a form in which fibrous activated carbon is wrapped with a synthetic resin nonwoven fabric.

From the comparison between the reference example and the comparative example 1, the following can be understood. In Comparative Example 1, it is considered that film formation unevenness occurred because some outgas component derived from the storage case was adsorbed on the substrate and the wettability of the substrate was deteriorated (hydrophobized). On the other hand, in the reference example , before the substrate was stored in the storage case, the outgas component in the case was removed by adsorption, and the adsorption of the outgas component to the substrate could be suppressed. As a result, the substrate could be stored in a clean state, and the uneven formation of the CrO film could be prevented.

From FIG. 7, it can be seen that the amount of outgas (acetonitrile) generated in the case is the largest immediately after the case is produced, and thereafter decreases with time, and becomes almost constant after the 21st day after the case is produced. In the reference example, it is considered that adsorption of outgas to the surface of the substrate 10 stored afterwards is suppressed by sufficiently adsorbing and removing the outgas generated immediately after the case preparation by the adsorbent before the substrate 10 is stored. .

From the comparison between the reference example and the comparative example 2, the adsorbent in which the activated carbon is dispersed in the gel-like medium used in the reference example does not generate dust or very little, so the storage case of the reference example cleans the substrate. It was found that it can be stored in a safe state.

1 case (storage case)
2 the case main body 3 lid 4, 5 adsorbent 10 for photomasks synthetic quartz glass board
2 1 bottom plate 22 first sidewall 23 second sidewall 24 flange 25 fitting portion 26 elastic member 27 supporting member 31 the upper plate 32, 33 the lid side wall 34 flange 37 tube

Claims (3)

A method of manufacturing a storage case for a synthetic quartz glass substrate or a photomask blank for a photomask,
Preparing a case formed by joining synthetic resin members;
Installing an adsorbent in which activated carbon is dispersed in a gel-like medium in the case and leaving it for a predetermined time;
Removing the adsorbent from the case;
Look including washing the said case the adsorbent has been removed,
When the adsorbent is placed and left in the case, the adsorbent is brought into contact with the joint portion of the synthetic resin member in the case,
A method for producing a storage case of a synthetic quartz glass substrate for a photomask or a photomask blank in which the adsorbent is removed from the case and the case is cleaned by washing the adsorbent with a cleaning agent .   The method for producing a storage case for a synthetic quartz glass substrate for a photomask or a photomask blank according to claim 1, wherein the cleaning agent is alcohol.   The case is
  A case body that is formed by joining a plurality of plate-shaped synthetic resin members including a bottom plate, and has an open top surface facing the bottom plate, and stores the synthetic quartz glass substrate for photomask or the photomask blank. When,
  A case that includes a lid that covers the opening and is detachably attached to the case body, and is formed by joining a plurality of plate-shaped synthetic resin members,
  3. The synthetic quartz glass substrate for photomask or the photomask blank according to claim 1, wherein the adsorbent is placed in contact with a part or all of a joint portion between the synthetic resin members in the case. Storage case manufacturing method.

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