JP4342863B2 - Mask blank storage container, mask blank storage method, mask blank storage body, and mask blank storage body transport method - Google Patents

Description

  The present invention relates to a photomask used for manufacturing an electronic device, a container for storing mask blanks used for manufacturing the photomask, and a method for storing the same.

  In recent years, electronic devices, particularly color filters or TFT elements for semiconductor elements and liquid crystal monitors, are required to be further miniaturized with the rapid development of IT technology. One of the technologies that support such a fine processing technology is a lithography technology using a photomask called a transfer mask. In this lithography technique, a fine pattern is formed on a silicon wafer by exposing an electromagnetic wave of an exposure light source to a silicon wafer with a resist film through a transfer mask. This transfer mask is usually manufactured by forming a pattern to be an original using a lithography technique on a mask blank in which a light-shielding film is formed on a translucent substrate. By the way, if there is foreign matter such as particles on the surface of the mask blank, it will cause defects in the pattern to be formed. Therefore, it is necessary to keep the surface of the mask blank clean so that the foreign matter does not adhere to the surface.

As a container for storing, storing, and transporting such mask blanks, a mask transport case as described in, for example, Patent Document 1 below has been conventionally known.
In other words, a conventional container for storing and storing mask blanks has an inner case called a carrier or the like that holds several to several tens of mask blanks and holds the inner case holding the mask blanks in an outer box (case body). ) And a cover on the outer box to accommodate the mask blanks. And by sticking an adhesive tape on the junction part of an outer box and a lid | cover, while sealing a case, it was trying to prevent entrance of external air, a foreign material, etc.
JP 2001-154341 A

As electronic devices have become more sophisticated in recent years, patterns formed on transfer masks are required to be further miniaturized, and the mask blanks are extremely clean to form such miniaturized patterns. Otherwise it will be unacceptable. Accordingly, it is necessary to keep the mask blanks as clean as possible, particularly during storage of the mask blanks, by suppressing the adhesion of foreign substances or the like to the mask blanks as much as possible.
Recently, a chemically amplified resist has attracted attention as a resist for a photomask. This chemically amplified resist is described in, for example, Japanese Patent Application Laid-Open No. 2000-66380. Since this chemically amplified resist is superior in characteristics such as sensitivity and contrast as compared with conventional photoresists, it can be said that it is advantageous for forming a miniaturized pattern. However, it has been pointed out that this chemically amplified resist is susceptible to chemical component contamination due to its reaction mechanism. That is, if there is contamination of a certain kind of chemical component, the function of a substance serving as a catalyst for a chemical amplification reaction is suppressed or inhibited (for example, deactivated), and desired performance may not be obtained. For this reason, in the case of mask blanks with a chemically amplified resist film, it is not necessary to simply remove foreign substances such as particles, and it is necessary to store in a particularly clean atmosphere in order to eliminate the influence of chemical component contamination. There is.

In conventional mask blank storage containers, for example, the joint between the outer box and the lid was sealed with adhesive tape, but the tape was affixed when mask blanks were stored and packed, and the tape was peeled off when opened. In addition to the time and effort, the sealed state was not perfect. That is, in the case of a commonly used adhesive tape, since it has some air permeability, the inside air may expand or contract depending on the temperature change of the atmosphere in which the storage container is stored. The entrance and exit between the outside air and the inside air occurs through the joint portion to which the tape is applied. In addition, the atmospheric pressure may fluctuate as in the case of carrying mask blanks on an aircraft. When transported by aircraft, the change in atmospheric pressure becomes considerably large, and thus ventilation between the outside air and the inside air occurs at this time. Therefore, even if mask blanks are stored and packed in a container in a clean atmosphere such as a clean room, depending on the subsequent storage atmosphere, the outside air may enter over time, and the inside of the storage container may be caused by some component contained in the outside air. May be contaminated.
Furthermore, even if a plastic or the like that does not easily release any chemical component is used as the material of the storage container, the chemical component used in the base material or adhesive of the adhesive tape enters the storage container over time. May be contaminated. In particular, when there is a change in the atmosphere such as the above-described temperature change or atmospheric pressure change, there is a risk that contamination by chemical components generated from the tape will accelerate.

In particular, in the case of the mask blank on which the above-described chemically amplified resist film is formed, contamination due to contamination such as chemical components becomes a fatal defect and must be avoided absolutely.
In this way, the mask blanks are stored and packed in a container in a clean room, and the joint between the outer box and the lid is sealed with an adhesive tape. Although it seems that it can be stored in an atmosphere, it was actually difficult to avoid contamination due to the ingress of outside air or chemical components of the adhesive tape.
Therefore, the present invention eliminates the above-mentioned conventional problems, prevents contamination by foreign substances such as chemical substances accompanying the entry of outside air, and provides a storage container and storage method that can store mask blanks and the like while maintaining a clean atmosphere. The first purpose is to provide it. It is a second object of the present invention to provide a storage method and a storage container suitable for a mask blank formed with a chemically amplified resist film that needs to be stored in a particularly clean atmosphere.

Conventionally, it is considered that mask blanks can be stored in a clean atmosphere by storing the mask blanks in a container in a clean atmosphere like a clean room, and sticking and sealing the adhesive tape at the joint of the container. However, according to the study of the present inventor, it has been found that it is difficult to maintain a clean atmosphere with time in the container containing the mask blanks by the conventional method. In particular, in the case of mask blanks having a chemically amplified resist film, if a conventional storage method is applied and stored, a desired fine pattern may not be formed during mask manufacturing, and stable resist performance may not be obtained. I also found out.
As a result of intensive studies to solve the above problems, the present inventor has removed foreign substances such as chemical substances contained in the outside air from entering the storage container even if the outside air enters the storage container being stored. Thus, it has been found that the mask blanks can be stored while keeping the inside of the storage container in a clean atmosphere even when outside air enters, and the present invention has been completed.

That is, the present invention has the following configuration.
(Configuration 1) A mask blank storage container that includes at least a container body that is open at the top and a lid that covers the container body, and stores mask blanks therein, and foreign matter in the outside air is contained in the storage container. A mask blank storage container comprising means for preventing entry.
(Structure 2) The means for preventing foreign matter in the outside air from entering the storage container removes the external air and internal air vent holes provided in the storage container and the external air foreign matter provided in the vent holes. The mask blank storage container according to the first aspect, comprising a filter member.
(Structure 3) A mask blank storage method comprising storing a mask blank having a resist film in the mask blank storage container according to Structure 1 or 2.
(Structure 4) The mask blank storage method according to Structure 3, wherein the resist film is a chemically amplified resist film.
(Structure 5) The mask blank storage method according to Structure 4, wherein the foreign matter in the outside air is a chemical substance that inhibits a desired chemical amplification effect in the chemical amplification resist.
(Structure 6) A mask blank storage body in which mask blanks are stored by the storage method according to any one of structures 3 to 5.
(Structure 7) A mask blank storage body transporting method comprising transporting the mask blank storage body according to Structure 6 using a transportation means.

  According to the present invention, in the mask blank storage container including a container body having an upper opening and a lid that covers the container body, a means for preventing foreign matter in the outside air from entering the storage container is provided. Therefore, it is possible to prevent outside air from entering the storage container as it is during storage.For this reason, foreign substances in the outside air, such as particles or any chemical substances contained in the outside air, enter the storage container and remove the mask blanks. It is possible to effectively prevent contamination. In other words, even if outside air enters the storage container during storage, the outside air can be cleaned, so that the mask blanks can be stored for a long period of time while keeping the inside of the storage container in a clean atmosphere. For this reason, it is possible to prevent the mask blanks from being contaminated by foreign substances such as chemical substances during storage, so that a high-quality transfer mask can be obtained using the stored and stored mask blanks.

As a means for preventing the foreign matter in the outside air from entering the storage container, for example, a filter member for removing a foreign matter in the outside air from the ventilation hole at the same time as providing a ventilation hole for the outside air and the inside air in the storage container. By providing, foreign substances such as chemical substances contained in the outside air are removed and cleaned by the filter member even if the outside air enters, so that contamination due to the entry of these foreign substances and chemical components can be prevented. The inside of the storage container can be kept in a clean atmosphere.
Further, according to the present invention, a mask blank having a resist film that is required to be stored and stored in a clean atmosphere, particularly a mask blank having a chemically amplified resist film that must be absolutely prevented from being contaminated by a chemical substance or the like. It is particularly suitable for storing and storing.
In addition, according to the present invention, when the mask blank storage body in which the mask blank is stored in the storage container is transported to a remote place or the like using a transportation means, the mask stored even if there is a change in the temperature or pressure of the outside air. Since the blanks are not contaminated, high reliability for transporting the mask blanks to a remote place or the like can be ensured.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1 to 4 show an embodiment of a mask blank storage container according to the present invention. FIG. 1 is a perspective view showing a cover of the storage container, and FIG. 2 shows a state in which the mask blank is stored in an inner case. FIG. 3 is a perspective view showing a container main body (outer case) of the storage container, and FIG. 4 is a longitudinal sectional view of the storage container with mask blanks stored therein.
In the storage container of this embodiment, a mask blank 1 in which a light-shielding thin film such as a chromium film is formed on one main surface of a glass substrate having a square main surface, and the above-described chemically amplified resist film is formed thereon, for example. Is housed in the middle case 2, the middle case 2 is housed in the container body 3, and the lid 4 is put on the opening side of the container body 3 (FIG. 4).
Note that the mask blanks 1 may be stored in the container main body 3 directly with a groove or the like without using the middle case 2. However, when the middle case 2 is used as in this embodiment, it is convenient because several to several tens of mask blanks can be handled in a state of being put in the middle case 2.

  In the middle case 2 of the present embodiment, a plurality of grooves 21 and 22 are formed from the opening side (upper side) to the bottom side (lower side) as a pair with one predetermined inner surface facing each other. Opening windows 23 and 24 and an opening 27 are provided on the bottom of the grooves 21 and 22 and the bottom of the middle case, respectively, and a substrate support 26 is formed on the bottom of the middle case. 26 supports the lower end face of the mask blank 1 (FIGS. 2 and 4). Then, concave surface portions 28 and 29 for accommodating and fixing the middle case 2 in the container body 3 are formed on the other opposite outer surfaces of the middle case from the bottom surface side to the middle of the opening portion side ( Figure 2). The height dimension from the upper end surface 25 on the opening side of the middle case 2 to the substrate support portion 26 corresponds to the main part of the height dimension of the mask blanks 1 to be accommodated. When stored, the upper portion of the mask blank 1 protrudes from the upper end surface 25 of the middle case 2 (FIG. 4). When several mask blanks 1 are inserted along the pair of grooves 21 and 22 of the middle case 2, these mask blanks stand in parallel with each other at a predetermined interval. In this embodiment, forests are formed in the vertical direction, but may be inclined.

The container body 3 of the present embodiment is formed with protrusions 31 and 32 adapted to abut against the concave portions 28 and 29 of the middle case 2 described above on the inner surfaces facing each other, and the bottoms of the protrusions 31 and 32. Is also joined to the bottom of the container body 3 (FIG. 3). In addition, convex portions 33 and 34 are formed on the opening side of one opposing outer surface. The outer peripheral surface 36 following the position slightly below the opening edge 35 of the container body 3 and the convex surfaces of the convex portions 33 and 34 are formed on substantially the same plane.
The lid 4 of the present embodiment has recesses in engagement pieces 41 and 42 extending from one opposing lower edge (the edge on the opening side to be inserted into the container body and facing upward in FIG. 1) 47. 43 and 44 are formed. Accordingly, when the lid 4 is put on the container body 3, the concave portions 43 and 44 are engaged with the convex portions 33 and 34 of the container main body 3, so that the lid 4 and the container main body 3 are fixed. (FIG. 4). Further, stoppers 45 and 46 that contact the upper end surface 25 on the opening side of the middle case 2 and support and fix the middle case 2 in the vertical direction are formed on one inner surface so as to face each other (FIG. 1). In addition, it is good also as a structure which can cover the lid | cover 4 as it is, without providing the recessed parts 43 and 44 of the lid | cover 4, and the convex parts 33 and 34 of the container main body 3. FIG. Further, even when the concave portion of the lid 4 and the convex portion of the container main body 3 are engaged, such engaging means may be formed not only on one side facing each other but also on each of the four sides.

The material of the above middle case 2, the container main body 3, and the lid | cover 4 is suitably selected from resin, such as a polypropylene, an acryl, polyethylene, a polycarbonate, polyester, polyamide, a polyimide, a polyethyl sulfite, for example. Among these, polycarbonate or polyester is preferable. The material of the container body 3 and the lid 4 is preferably polycarbonate, and the material of the middle case 2 is preferably polyester. As this polyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and the like are preferable. In addition, if charges are accumulated during storage of mask blanks, discharge breakdown may occur in the mask manufacturing process, resulting in pattern defects. For example, carbon or the like is mixed into the constituent resin of the container body 3 to provide conductivity. It is preferable.
When the lid 4 is put on the container body 3 and the recesses 43 and 44 of the lid 4 are engaged with the projections 33 and 34 of the container body 3 to fix the lid 4 and the container body 3, the lower edge of the lid 4 The outer peripheral surface 48 that follows and the outer peripheral surface 36 that follows the opening edge of the container main body 3 are overlapped and joined in the front-rear direction.

In the present embodiment, a vent hole 49 for outside air and inside air is formed at one corner of the lid 4, and the filter member 5 is attached to the vent hole 49 toward the inside of the lid 4 ( 1 and 4). The filter member 5 has a configuration in which pipes 51 and 53 that are gas flow paths are integrally formed on both sides of a bowl-shaped filter holding portion 52 that holds a filter therein. The 51 side is attached to the vent hole 49 of the lid 4, and the pipe 53 side is directed inward of the lid 4. The filter holding part 52 can be divided, and is configured so that an internal filter can be attached and detached. In addition, the corner part of the lid | cover 4 which provided the vent hole 49 is dented inward, and the said filter holding part 52 is made to contact | abut on the concave surface.
Therefore, even if the outside air enters through the vent hole 49 in a state where the mask blanks are stored and stored in the storage container according to the present embodiment, foreign substances such as chemical substances contained in the outside air are removed by the filter member 5. Since only the clean outside air enters the container as it is, the cleanliness inside the container is maintained.

As a filter used for the said filter member 5, the air filter normally used in a clean room can be used, for example. Preferred examples of such a filter include a HEPA filter (high efficiency particulate air filter) and a ULPA filter (ultra low penetration particulate air filter). The HEPA filter is a high-efficiency air filter, which is mainly used for air purification in a clean room, and is mainly made of glass fiber. The ULPA filter is an ultra-high performance filter developed along with the miniaturization of VLSI manufacturing, and is mainly made of glass fiber or fluorine resin. The filter is preferably a filter that can capture particles of 0.05 μm or more. The selection of an air filter such as a HEPA filter or a ULPA filter can be appropriately selected in consideration of cost effectiveness. In practice, a HEPA filter can be used.
In addition, when storing and storing mask blanks having a chemically amplified resist film that needs to eliminate contamination by chemical substances, a filter (chemical filter) that adsorbs chemical substances is used alone or in combination with the air filter. It is preferable. As such a chemical filter, for example, an activated carbon filter or an ion exchange filter can be preferably used. The selection of a chemical filter such as an activated carbon filter or an ion exchange filter can be appropriately selected in consideration of cost effectiveness. In practical use, an activated carbon filter can be used.
Such chemical amplification resist is contaminated, that is, the desired chemical amplification effect of the chemical amplification resist is inhibited (the chemical amplification effect is enhanced or suppressed as compared with the desired, and a predetermined resist pattern is formed. Examples of chemical substances to be removed include acidic chemical substances and basic chemical substances. Examples of acidic chemical substances include substances containing chlorine ions, substances containing sulfate ions, substances containing phosphate ions, substances containing nitrate ions, and the like. In addition, examples of the basic chemical substance include nitrogen-containing compounds such as ammonia, amines, anilines, and nitriles that suppress or inhibit (for example, deactivate) the function of an acid serving as a catalyst for a chemical amplification reaction.

As described above, according to the storage container of the present embodiment, foreign substances such as chemical substances contained in the outside air are filtered out even if the outside air enters from the vent hole 49 during storage and storage of mask blanks and the like. Since entry into the container is prevented by the member 5, it can be stored while maintaining a clean atmosphere when the mask blanks are stored for a long period of time, and outside air enters the container as it is and is included in it. There is no risk of contamination by foreign substances such as chemical substances. Accordingly, the present invention is suitable for storing and storing mask blanks having a chemically amplified resist film that is easily influenced by the environment in which it is stored and that is required to be stored in a clean atmosphere.
It should be noted that the joint between the lid 4 and the container body 3, that is, the outer circumferential surface 48 that follows the lower edge of the lid 4 when the lid 4 is placed on the container body 3 and the outer circumferential surface 36 that follows the opening edge of the container body 3 In general, it is conceivable that the outside air enters from the joint portion overlapped with each other. However, as in the present embodiment, the vent hole 49 is provided in the container so that even if outside air enters, the air hole 49 is preferential. Therefore, contamination in the container can be sufficiently prevented.

Further, in the present embodiment, the vent hole 49 and the filter means 5 are provided at one place in the corner of the lid 4, but it is not necessary to be limited to this at all. If it is, it may not be a corner, and it may be provided not at one place but at a plurality of places. Moreover, you may provide in the suitable location of a side wall board instead of the top plate of the lid | cover 4 like this embodiment, and you may provide in the container main body 3 side further.
The means for preventing foreign substances contained in the outside air from entering the container is not limited to the present embodiment. For example, a configuration may be adopted in which a filter or a sealing member having a filter function is directly attached so as to cover or close a vent hole provided at an appropriate location of the container from the inside of the container. Further, without providing such a vent hole, a filter or a member having a filter function or the like may be provided at the joint between the lid 4 and the container body 3.
The mask blank to which the present invention is applied is a mask blank in which a light-shielding film such as Cr is formed on a light-transmitting substrate such as a glass substrate, and a phase in which a halftone (semi-transparent) film is formed on the substrate. Includes mask blanks for shift masks, and mask blanks for reflective masks in which, for example, a Mo / Si multilayer reflective film that reflects exposure light and a Ta-based absorber film that absorbs exposure light are formed on the substrate. . Needless to say, the present invention is not limited to square mask blanks and the like, and can be applied to other shapes such as a disk-shaped substrate.
Hereinafter, the present invention will be described with reference to specific examples.

A halftone film was formed on a quartz substrate (6 inches × 6 inches) by a sputtering method, and a resist film was formed thereon by a spin coating method to produce a mask blank with a resist film. At this time, a MoSi-based metal film was used as the halftone film, and a positive chemically amplified resist film was used as the resist film.
100 mask blanks manufactured in this way were stored separately in 10 storage containers of the embodiment shown in FIGS. 1 to 4 described above. The lid and container body were made of polycarbonate, and the middle case was made of polybutylene terephthalate. Moreover, as a filter of the filter member attached to the container, an activated carbon filter and a HEPA filter were used in combination. The storing operation was performed in a clean room cleaned with an activated carbon filter and a ULPA filter.
This storage container was further packed in a packing bag, and cargo was transported by aircraft. Then, the transported storage container was opened in a clean room similar to the above, and a predetermined electron beam was drawn on the taken-out mask blanks, followed by predetermined development and etching to produce a phase shift type transfer mask. . When the quality of the manufactured phase shift mask was examined in detail with a scanning electron microscope, no particularly problematic defect was found from any of the 100 sheets.

(Comparative example)
In the above-described embodiment, a conventional storage container in which the vent hole and the filter member are not provided in the container (the material of the lid, the container main body, and the inner case is the same as that of the embodiment) is used, Mask blanks were manufactured, stored, and transported in the same manner as in the examples except that the adhesive tape was attached to the joint portion of the container and sealed.
When the quality of the phase shift mask manufactured using the mask blanks after transport in the same manner as in the example was inspected in detail with a scanning electron microscope, the line width of the pattern was disturbed from any of the 100 sheets. It was discovered that This is considered to be because outside air entered the container as it was from the junction of the storage container during transportation, and the chemically amplified resist film of the mask blank was chemically contaminated by some chemical component. It is done.

It is a perspective view which shows the cover of a storage container. It is a perspective view which shows the state which accommodates mask blanks in a middle case. It is a perspective view which shows the container main body (outer case) of a storage container. It is sectional drawing of the vertical direction of the state which accommodated the mask blanks in the storage container.

Explanation of symbols

1 Mask Blanks 2 Middle Case 3 Container Body 4 Lid 5 Filter Member 49 Vent

Claims (9)

At least, a container for storing mask blanks that includes a container body that is open at the top and a lid that covers the container body, and stores mask blanks having a chemically amplified resist film therein,
If the outside air has entered the storage container during storage, the acidic chemicals in the ambient air which inhibit desired chemical amplification effect in the chemically amplified resist comprising a means for preventing from entering the storage container A storage container for mask blanks. The means for preventing the acidic chemical substance in the outside air from entering the storage container removes the vent hole between the outside air and the inside air provided in the storage container and the acidic chemical substance in the outside air provided in the ventilation hole. The mask blank storage container according to claim 1, further comprising a filter member. 3. The acidic chemical substance according to claim 1 or 2 , wherein the acidic chemical substance is at least one of a substance containing chlorine ions, a substance containing sulfate ions, a substance containing phosphate ions, and a substance containing nitrate ions. The mask blank storage container described. The mask blank storage container according to claim 2, wherein the filter member is detachably attached to the vent hole.   5. The mask blank storage container according to claim 2, wherein the filter member is a chemical filter including an activated carbon filter or an ion exchange filter.   6. The mask blank storage container according to claim 5, wherein the filter member further includes an air filter made of glass fiber or fluorine resin. A mask blank storage container according to any one of claims 1 to 6, is prepared,
Producing a mask blank having the chemically amplified resist film,
A method for storing mask blanks, comprising: storing the manufactured mask blanks in the storage container.   8. A mask blank housing body in which mask blanks having a chemically amplified resist film are housed by the housing method according to claim 7.   A method for transporting a mask blank storage body, comprising transporting the mask blank storage body according to claim 8 using a transportation means.

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