JP2016173414A - Pellicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pellicle capable of reducing distortion of a mask for photolithography when crimped to the mask and capable of decreasing a positional deviation of a transfer pattern by maintaining flatness of the mask.SOLUTION: A pellicle 1 has: a pellicle film pasted on one end face 2e of a pellicle frame 2; and an adhesive layer with a residual stress value of 1.0 mN/mm2 or higher and 12.0 mN/mm2 or lower after 20% expansion/24h relaxation, adhered on the other end face 2f of the pellicle frame so that a degree of flatness in circumferential direction is 15 μm or less. The pellicle is pasted on a mask.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pellicle used as a dust guard for a photolithography mask or the like.

In a photolithography process for manufacturing a semiconductor, a semiconductor manufacturing apparatus such as a stepper (reduction projection exposure apparatus) is used to form a photoresist pattern corresponding to an integrated circuit on a wafer.
2. Description of the Related Art In recent years, the wavelength of exposure light used in a photolithography process has been shortened along with the high integration of semiconductor manufacturing apparatuses. That is, there is a demand for a technique capable of drawing a fine pattern with a narrower line width when forming a photoresist pattern on a wafer. In order to deal with this, for example, as stepper exposure light, the conventional g-line (wavelength 436 nm), i-line (wavelength 365 nm), proceeding from KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), Light having a shorter wavelength such as an F ₂ excimer laser (wavelength 157 nm) has been used.

Double patterning is known as a technique for drawing a fine pattern, and exposure is usually performed twice using two masks. For this reason, it is important to increase the positional accuracy between the two patterns to be formed. That is, if the positional accuracy between the pattern obtained by the first exposure and the pattern obtained by the second exposure is low, a desired pattern cannot be obtained. For this reason, since it is necessary to reduce the positional deviation between the two patterns to be formed, the mask is required to have flatness.
As a cause of impairing the flatness of the mask, mask distortion occurs when a pellicle is affixed to the mask, and it is considered that deformation and bending of the pellicle itself affect the mask. In general, the flatness of the mask is several μm or less, and the most advanced product is 1 μm or less. However, it is known that the flatness of the pellicle frame (hereinafter referred to as “frame”) is several tens of μm, which is higher than that of the mask. Therefore, as in Patent Document 1, a pellicle is disclosed in which the flatness of the frame is 15 μm or less and the flatness of the straight portion of the frame is 10 μm or less.
Further, Patent Document 2 discloses that mask distortion is reduced by increasing the flatness of a mask adhesive actually attached to a mask.

Japanese Patent Laying-Open No. 2015-1683 JP 2009-25560 A

However, in order to cope with oblique incidence due to further miniaturization and immersion exposure in recent years, the demand for mask distortion reduction has become stricter, and a pellicle meeting the demand is still desired.
As in Patent Document 1, it is important to reduce the flatness of the frame. However, there is a limit in processing, and there is a case where distortion due to stress may occur due to heat treatment in the pellicle manufacturing process. There are places where it is difficult to maintain.
Further, in the case of the flatness in the circumferential direction of the mask adhesive as in Patent Document 2, the mask distortion is small and large even when the adhesive measured by the measurement method described in Patent Document 2 is used. It has been found that the variation is large.
Therefore, the problem to be solved by the present invention is to provide a pellicle that stably reduces mask distortion when it is pressure-bonded to a mask.

  As a result of intensive studies by the present inventors, it has been found that the above problem can be solved by reducing the flatness of the pellicle mask adhesive in the cross-sectional direction, and the present invention has been completed.

The present invention is as follows.
[1] a pellicle frame;
A pellicle film stretched on one end surface of the pellicle frame;
An adhesive layer attached to the other end surface of the pellicle frame,
The pellicle whose flatness of the cross-sectional direction of the said adhesive layer is 20 micrometers or less.
[2] The pellicle according to [1], wherein the adhesive layer has a circumferential flatness of 15 μm or less.
[3] When the shape of the cross section that appears when the pressure-sensitive adhesive layer is cut in a direction perpendicular to the direction parallel to the side of the pellicle frame is observed at any 12 points, the outer height is increased at 6 points or more. The pellicle according to [1] or [2], wherein the pellicle has a shape that is higher than the height of the inner or central portion.
[4] The pressure-sensitive adhesive layer according to any one of [1] to [3], wherein the residual stress value after 20% elongation / 24-hour relaxation is 1.0 mN / mm ² or more and 12.0 mN / mm ² or less. Pellicle.
[5] The pellicle according to any one of [1] to [4], wherein the height difference in the cross section that appears when the adhesive layer is cut at an angle of 45 degrees at each corner is 10 μm or less. .

  ADVANTAGE OF THE INVENTION According to this invention, the pellicle which reduced the mask distortion when crimping | bonding to a mask can be provided.

1 is a perspective view showing a pellicle according to an embodiment of the present invention. It is the II-II sectional view taken on the line in FIG.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

The pellicle of this embodiment includes a pellicle frame, a pellicle film stretched on one end face of the pellicle frame, and an adhesive layer attached to the other end face of the pellicle frame, and a cross-sectional direction of the adhesive layer Has a flatness of 20 μm or less.
FIG. 1 is a perspective view showing a pellicle as one embodiment according to the present embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG. As shown in FIGS. 1 and 2, the pellicle 1 includes a pellicle frame 2, a pellicle film 3 stretched on one end surface 2 e of the pellicle frame 2, and an adhesive layer 10 attached to the other end surface 2 f of the pellicle frame 2. And. The pellicle 1 shown in FIGS. 1 and 2 includes a protective film F that protects the pressure-sensitive adhesive layer 10.

In the present embodiment, the pressure-sensitive adhesive layer is provided on the end surface (“other end surface”) opposite to the surface on which the pellicle film of the pellicle frame is stretched. This pressure-sensitive adhesive layer is for attaching and fixing the pellicle to a mask, and is provided over the entire circumference of the other end surface of the pellicle frame.
In this embodiment, the flatness in the cross-sectional direction of the pressure-sensitive adhesive layer is 20 μm or less. Furthermore, 1 micrometer-15 micrometers are preferable, and 2 micrometers-13 micrometers or less are more preferable especially. By being in this range, the flatness in the cross-sectional direction attached to the mask becomes constant, and the mask distortion can be reduced conventionally by applying the load at the time of application uniformly to the entire adhesive.
Further, when the flatness is smaller than 1 μm, when the pellicle is pasted on the mask, there is a case where bubbles are lost when the pellicle is involved, and the flatness is preferably 1 μm or more.

Here, the cross-sectional direction of the pressure-sensitive adhesive layer refers to a direction perpendicular to the direction parallel to the side of the pellicle frame.
The flatness in the cross-sectional direction of the pressure-sensitive adhesive layer is obtained by subtracting the height of the lowest point from the height of the highest point in the cross-section in the cross-sectional direction for any 12 points of the pressure-sensitive adhesive layer on the pellicle frame. Value (height difference) is measured, and the average value of the obtained 12 points is calculated. Here, “in the cross section” and “height” refer to the distance from the interface between the other end surface of the pellicle frame and the pressure-sensitive adhesive layer to the surface of the pressure-sensitive adhesive layer (the surface attached to the mask).
Specifically, it is measured as follows.

The flatness in the cross-sectional direction of the pressure-sensitive adhesive layer can be measured using a laser displacement meter after the protective film F is slowly peeled off so that the shape of the pressure-sensitive adhesive layer does not change after the pellicle is produced. In addition, when the value of flatness is not influenced by the protective film F, it may be measured with the protective film F attached.
For each side, select a total of three points, one point in the center of the side and one point within 20 mm on the left and right sides, and a cross section in the cross-sectional direction of the adhesive layer for a total of 12 points for four sides ( Observe the shape of the cross section that appears when cutting in a direction perpendicular to the direction parallel to the side of the pellicle frame, without actually cutting, using a laser displacement meter. A value obtained by subtracting the height of the lowest part from the height of the part is obtained, and the average value of the above 12 points is defined as the flatness in the cross-sectional direction of the pressure-sensitive adhesive layer.

  Furthermore, the difference in elevation in a cross section in a direction of 45 degrees at each corner of the pressure-sensitive adhesive layer (a cross-section that appears when the pressure-sensitive adhesive layer is cut at the corner in a direction connecting the outer corner and the inner corner). Are preferably 10 μm or less. In particular, 1 μm to 8 μm, and more preferably 1 to 6 μm are preferable. By doing so, the corner portion is stably attached to the mask and the twist with the central portion of the side is reduced, so that the mask distortion is further improved.

Further, the flatness in the circumferential direction of the pressure-sensitive adhesive layer is preferably 15 μm or less. When the flatness in the circumferential direction is 15 μm or less while having the flatness in the cross-sectional direction as described above, the flatness of the pellicle as a whole is increased and mask distortion can be further reduced. Furthermore, 1 μm to 13 μm is preferable, and 2 μm to 11 μm or less is particularly preferable.
Here, the circumferential direction of the pressure-sensitive adhesive layer refers to a direction parallel to the side of the pellicle frame. And the flatness of the circumferential direction of an adhesive layer and the value obtained as follows are said.
When the pressure-sensitive adhesive layer is cut at the center of its width (the center in the cross-sectional direction) in parallel to the side of the pellicle frame, its height is increased at a total of 8 points, 4 at the center of each side and 4 at the corners. The value obtained by subtracting the lowest value from the highest value is defined as the flatness in the circumferential direction.

The flatness in the circumferential direction of the pressure-sensitive adhesive layer can be measured without actually cutting the pressure-sensitive adhesive layer by measuring using a laser displacement meter. Prior to measurement, the protective film F is slowly peeled off so that the shape of the pressure-sensitive adhesive layer does not change. However, when the flatness value is not affected by the protective film F, the protective film F remains attached. You may measure.
The flatness in the cross-sectional direction and the circumferential direction of the pressure-sensitive adhesive layer is within the above range by improving the flatness of the pellicle frame or adjusting the conditions of the coating molding machine used when the pressure-sensitive adhesive layer is provided on the pellicle frame. Can be adjusted.
The conditions of the molding machine are not limited, but for example, it is particularly effective to perform molding by sandwiching it between a platen with high flatness or in two stages. Further, when molding is performed in two stages, the molding temperature is preferably set higher than the temperature of the first stage. The molding temperature can be appropriately determined according to the composition of the pressure-sensitive adhesive composition, but the first stage molding temperature is preferably about 70 to 180 ° C, and the second stage molding temperature is 150 ° C to It is preferable that it is about 210 degreeC.
The flatness of the pellicle frame is desirably 15 μm or less in the circumferential direction of the pellicle frame.

The shape of the cross-section of the pressure-sensitive adhesive layer (the cross-section when cut perpendicular to the direction parallel to the side of the pellicle frame) is such that the height of the outside (outside of the pellicle frame) is at the center or inside (of the pellicle frame). It is preferable that it is higher than the height of the opening side.
By adopting such a structure, air bubbles can be easily removed when affixed to the mask, and there is no concern about an air path or the like. The height of the outer side is more preferably higher than the height of the central part and the inner part, and in particular, the outer part is the highest, the central part is the lowest, and the inner part is lower than the outer part but higher than the central part. In this case, in addition to easy removal of bubbles, the load of the pellicle is uniformly applied to the mask at the time of attachment, which is further preferable.
The cross-sectional shape in the cross-sectional direction of the pressure-sensitive adhesive layer can be confirmed by observing 12 cross-sections, as in the case of measuring the flatness in the cross-sectional direction described above. In this case, among the 12 points, it is preferable that the above condition is satisfied at least 6 points or more, it is more preferable that 9 points or more are satisfied, and it is particularly preferable that all are satisfied.
The cross-sectional shape of the pressure-sensitive adhesive layer can be set to the above-described shape by setting the conditions of the coating molding machine used when the pressure-sensitive adhesive layer is provided on the pellicle frame so as to have the above-mentioned shape.

Further, the residual stress value α after relaxation of 20% elongation / 24 hours of the pressure-sensitive adhesive layer is preferably 1.0 to 12.0 mN / mm ² .
In the present embodiment, “20% elongation / residual stress value after 24 hours” means a residual stress value α when the adhesive layer is relaxed for 24 hours after 20% elongation.

In general, it is said that it takes about 24 hours for the pellicle-attached mask to be stabilized after the pellicle is attached to the mask using an adhesive. Conventionally, with regard to mask deformation, only deformation immediately after pasting has been considered, but the present inventors have reduced residual stress immediately after pasting if the residual stress after pasting stability is small, and therefore immediately after pasting. It has been found that this is preferable because the force for deforming the mask from the time until the stabilization becomes small.
That is, in addition to setting the flatness in the cross-sectional direction of the pressure-sensitive adhesive layer to 20 μm or less, paying attention to the residual stress after sticking stability, and further reducing the mask distortion by setting the residual stress value α to a specific range. be able to.
The larger the residual stress value α, the larger the residual stress, and the stronger the force for deforming the mask, the larger the mask distortion. On the other hand, the smaller the value of α is, the smaller the force for deforming the mask is, but there is a possibility that the mask and the pellicle are displaced when storing the mask.
From the above viewpoint, in the present embodiment, it is preferable that the residual stress value α is in the range of 1.0 to 12.0 mN / mm ² . It has been found that by making such a range, the mask distortion is reduced and the mask and the pellicle do not shift during mask storage.
Residual stress value alpha, more preferably 2.5 mN / mm ² or more 11.0mN / mm ² or less, and more preferably 3.5 mN / mm ² or more 10.5mN / mm ² or less. If the residual stress value α is within this range, the residual stress particularly immediately after application becomes small, and the force for deforming the mask immediately after stabilization becomes small, which is particularly preferable for mask distortion.
Further, the residual stress value α is, inter alia preferably at 5.5mN / mm ² or more 9.0mN / mm ² or less, particularly preferably 6.0mN / mm ² or more 8.5mN / mm ² or less. If the residual stress value α is within this range, the cohesive force is also appropriate, so that the adhesive residue when the pellicle is peeled from the mask can be reduced.
The residual stress value α of the pressure-sensitive adhesive layer can be adjusted to the above range depending on the composition ratio of the pressure-sensitive adhesive composition and the amount of the curing material.

Further, the stress retention rate (%) of the pressure-sensitive adhesive layer (the ratio of the residual stress value α to the maximum stress value α _max when the pressure-sensitive adhesive layer is extended by 20% (α / α _max × 100)) is 35% or more. It is preferable that It is preferable that the stress retention is in this range since the stress of the pressure-sensitive adhesive layer is hardly applied to the mask.
The stress retention rate of the pressure-sensitive adhesive layer can be adjusted to the above range by using a highly flexible material as the pressure-sensitive adhesive.

In this embodiment, it is preferable that an adhesive layer contains a synthetic resin as an adhesive. When the pressure-sensitive adhesive layer contains a synthetic resin as a pressure-sensitive adhesive, it becomes easy to adjust the flatness in the cross-sectional direction of the pressure-sensitive adhesive layer to 15 μm or less. Examples of the synthetic resin include acrylic resins, synthetic rubber resins, and silicone resins from the viewpoint of light resistance and haze.
As the acrylic resin, a non-crosslinked acrylic resin or a crosslinked acrylic resin may be used. As the non-crosslinked acrylic resin, a (meth) acrylic ester elastomer is preferably used.
As the synthetic rubber resin, a styrene elastomer and an olefin elastomer are preferably used.

((Meth) acrylic ester elastomer)
As the (meth) acrylic ester elastomer, an acrylic base polymer (A) is preferable, and it is preferable to use a tackifier in combination.
The (meth) acrylic acid ester elastomer may be used alone or in combination of two or more.
In this embodiment, “(meth) acrylic acid” means “acrylic acid” and “methacrylic acid” corresponding thereto.

  As the acrylic base polymer (A), the glass transition temperature (Tg) on the low temperature side is −20 ° C. or lower and −80 ° C. or higher from the viewpoint of adjusting the residual stress value α and the stress retention rate to preferable ranges. Preferably, it is −25 ° C. or lower, −70 ° C. or higher, more preferably −30 ° C. or lower, −60 ° C. or higher.

From the viewpoint that the acrylic base polymer (A) can be applied to the pellicle frame with a thick adhesive layer, and mask distortion when the pellicle is attached to the mask can be further reduced. A copolymer is preferred.
The block copolymer is preferably a block copolymer (I) having a structure represented by the general formula (I): (a1)-(b)-(a2). Here, (a1) and (a2) are polymer blocks made of the same monomer.
The glass transition temperature Tg of the polymer blocks (a1) and (a2) in the general formula (I) is preferably 80 ° C. or higher. It is preferable that the glass transition temperatures of (a1) and (a2) are 80 ° C. or higher, particularly because sufficient holding power and cohesive strength at high temperatures can be obtained.
Moreover, it is preferable that the glass transition temperature Tg of the polymer block (b) in general formula (I) is 30 degrees C or less. Moreover, when (b) of general formula (I) is a copolymer, it is preferable to have in the main chain the polymer part whose glass transition temperature Tg is 30 degrees C or less. It is preferable that the glass transition temperature of (b) is 30 ° C. or lower, since sufficient adhesive strength and holding power can be obtained.
In addition, the glass transition temperature of each polymer block can be calculated | required from the several peak obtained when a DSC measurement is performed about an acrylic type base polymer (A).

Polymer blocks represented by (a1) and (a2) of the general formula (I) (hereinafter, the polymer block (a1) and the polymer block (a2) may be collectively referred to as “polymer block a”). It is preferable that the monomer component which comprises is mainly a methacrylic acid alkyl ester having 1 to 14 carbon atoms from the viewpoint of setting the glass transition temperature of the polymer block a to 80 ° C. or higher.
Here, “mainly” means that the alkyl methacrylate having 1 to 14 carbon atoms occupies at least 50 mass%, preferably 80 mass% or more of the entire polymer block a.
Further, at least one of the polymer blocks (a1) and (a2) may be composed of a methacrylic acid alkyl ester having 1 to 14 carbon atoms.

Specific examples of the alkyl ester having 1 to 14 carbon atoms as the monomer component constituting the polymer block a include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n methacrylate. -Butyl, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate , Tridecyl methacrylate, 2-hexyldecyl methacrylate and the like.
From the viewpoint of setting the glass transition temperature of the polymer block a to 80 ° C. or higher, the monomer component includes methacrylic acid such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and the like having 3 or less carbon atoms. An ester composed of alcohol is preferable.
The aforementioned C1-C14 methacrylic acid alkyl ester may be used singly or in combination of two or more.

In the polymer block a, monomer components other than alkyl methacrylate having 1 to 14 carbon atoms, preferably less than 50% by mass, more preferably 20% by mass or less, may be used.
Specific examples of the monomer component include, for example, methacrylic acid esters other than methacrylic acid alkyl esters such as trimethylsilyl methacrylate, trimethoxysilylpropyl methacrylate, glycidyl methacrylate, and allyl methacrylate; methyl acrylate, n-butyl acrylate And alkyl acrylates such as t-butyl acrylate; olefins such as ethylene and propylene; and lactones such as ε-caprolactone and valerolactone.
The monomer component may be used alone or in combination of two or more.

The monomer component constituting the polymer block represented by (b) in the general formula (I) (hereinafter referred to as “polymer block b”) is mainly an alkyl acrylate ester having 1 to 14 carbon atoms and / or methacrylic acid. An alkyl ester is preferable from the viewpoint of setting the glass transition temperature of the polymer block b to 30 ° C. or less.
Here, “mainly” means that at least 50% by mass, preferably 80% by mass or more of the entire polymer block b is occupied by an alkyl acrylate and / or methacrylic acid alkyl ester having 1 to 14 carbon atoms. Means that

Specific examples of the alkyl ester having 1 to 14 carbon atoms as the monomer component constituting the polymer block b include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and acrylic acid n. -Butyl, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and the like.
When alkyl acrylate is used as the main monomer component, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, or the like is used from the viewpoint of setting the glass transition temperature of polymer block b to 30 ° C. or lower. Is preferred.

As a specific example of a C1-C14 methacrylic acid alkyl ester as a monomer component which comprises the polymer block b, it is C1-C14 previously mentioned as a specific example of the monomer component which comprises the polymer block a. The compound similar to the alkyl methacrylate is mentioned.
When alkyl methacrylate is used as the main monomer component, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, isopentyl methacrylate, methacrylic acid are used from the viewpoint of setting the glass transition temperature of polymer block b to 30 ° C. or lower. It is preferable to use an ester composed of methacrylic acid and an alcohol having 4 or more carbon atoms, such as n-hexyl acid, 2-ethylhexyl methacrylate, pentadecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyldecyl methacrylate.
The said C1-C14 alkyl acrylate ester and / or methacrylic acid alkyl ester may be used by 1 type, or may be used 2 or more types.

The polymer block b is preferably less than 50% by mass, more preferably 20% or less, within a range that does not adversely affect the adhesive residue on the mask and light resistance, and / or an alkyl acrylate ester having 1 to 14 carbon atoms and / or Alternatively, monomer components other than methacrylic acid alkyl ester may be used.
The monomer component may be used alone or in combination of two or more.
Examples of the monomer component include methacrylic acid esters other than methacrylic acid alkyl esters such as trimethylsilyl methacrylate, trimethoxysilylpropyl methacrylate, glycidyl methacrylate, and allyl methacrylate; olefins such as ethylene and propylene; ε-caprolactone, valerolactone And the like.

In the block copolymer (I) represented by the general formula (I), one polymer block b ((b)) is present between two polymer blocks a ((a1) and (a2)). It has a positioned structure. If such a structure consisting of three polymer blocks (a1), (a2) and (b) is included, not only a block copolymer composed of only these three polymer blocks, It may be a block copolymer composed of four or more polymer blocks including one or more other polymer blocks.
The polymer block (a1), (a2) and (b) may be the same polymer block as the polymer block a or the polymer block b, and the polymer block a or the polymer block b. Another type of polymer block c may be used. Examples of the polymer block c of another type include polymer blocks composed of olefins such as ethylene and propylene, and lactones such as ε-caprolactone and valerolactone.

  As specific structures of the block copolymer (I), (a1)-(b)-(a2), (a1)-(b)-(a2)-(b), (a1)-(b) Examples thereof include block copolymers such as-(a2)-(c). The polymer block represented by (a1) or (a2) may be the same type of polymer block or a different type of polymer block.

The molecular weight of the block copolymer (I) is preferably in the range of 10,000 to 500,000 in terms of weight average molecular weight, more preferably in the range of 30,000 to 450,000, More preferably, it is in the range of 000 to 400,000. When the weight average molecular weight is in such a range, the adhesive residue of the pressure-sensitive adhesive layer is improved, and mask distortion can be reduced by thickly applying the pressure-sensitive adhesive, which is preferable.
Further, from the same viewpoint, as the molecular weight distribution, M _W / M _N is preferably 1.0 to 2.0. Here, M _W is the weight average molecular weight, M _N is the number average molecular weight.
By polymerizing by the living polymerization method, the weight average molecular weight of the block copolymer can be in the range of 10,000 to 500,000, and a block copolymer having a small molecular weight distribution and few impurities can be obtained. .

In the block copolymer (I), the ratio (a / b) of the total mass of the polymer block a to the total mass of the polymer block b contained in the molecule is preferably 5/95 to 80/20. More preferably, the ratio is 10/90 to 75/25.
When a / b is within the above range, the cohesive force can be sufficiently obtained while maintaining the softness as the pressure-sensitive adhesive layer, and a high holding force can be obtained, so that mask distortion can be reduced.

The block copolymer (I) may have a side chain having a bulky branched structure. Since the block copolymer has a side chain with a bulky branch structure, it is possible to apply a thick adhesive layer, and to further reduce mask distortion when the pellicle is attached to the mask. Become.
Further, the block copolymer (I) has a hydroxyl group in the molecular side chain or at the molecular main chain end, so as not to adversely affect the adhesive residue on the mask and the light resistance as the acrylic base polymer (A). You may have functional groups, such as a carboxyl group, an acid anhydride group, and an amino group.

  Commercially available products may be used as the block copolymer (I). Specific examples thereof include a trade name “Clarity (registered trademark)” series (manufactured by Kuraray Co., Ltd.) and a trade name “Nanostrength” series (Arkema Co., Ltd.). And the like.

(Styrene elastomer)
As a styrenic elastomer, a vinyl aromatic compound unit can be applied from the viewpoint that a pressure-sensitive adhesive layer can be thickly applied to a pellicle frame and mask distortion when the pellicle is attached to a mask can be further reduced. A block having at least two polymer blocks mainly composed of (hereinafter referred to as “polymer block d”) and at least one polymer block mainly composed of conjugated diene units (hereinafter referred to as “polymer block e”). Copolymer (II) is preferred, and a tackifier is preferably used in combination.
The block copolymer (II) may be an unhydrogenated product or a hydrogenated product. Moreover, this block copolymer (II) may be used by 1 type, or may be used 2 or more types.

The polymer block d is mainly composed of vinyl aromatic compound units.
Examples of the vinyl aromatic compound unit constituting the polymer block d include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4 -Structural units derived from vinyl aromatic compounds such as dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, vinyltoluene, 1-vinylnaphthalene and 2-vinylnaphthalene. Among these, structural units derived from styrene and α-methylstyrene are preferable.
Here, “mainly” means that the proportion of vinyl aromatic compound units in the polymer block d exceeds 50% by mass.
The aromatic vinyl compound unit may be used alone or in combination of two or more.

The polymer block e is mainly composed of conjugated diene units.
The conjugated diene unit constituting the polymer block e means a structural unit derived from a diolefin compound having at least a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3. -Structural units derived from conjugated diene compounds such as butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. Among these, structural units derived from 1,3-butadiene and isoprene are preferable.
Here, “mainly” means that the proportion of conjugated diene units in the polymer block e exceeds 50% by mass.
The conjugated diene unit may be used alone or in combination of two or more.

The mass fraction of the polymer block e in the block copolymer (II) is not particularly limited, but is preferably 60% by mass or more, and more preferably less than 65% by mass.
When the mass fraction of the polymer block e is 60% by mass or more, since the polymer block e having flexibility is large, the residual stress value α of the pressure-sensitive adhesive layer can be reduced. Moreover, since the moldability which maintains a shape is also maintained, it is more preferable.
The mass fraction can be measured by, for example, ¹ H-NMR spectrum.

  When the polymer block e is composed of two or more kinds of conjugated diene units (for example, 1,3-butadiene units and isoprene units), there are no particular limitations on the composition ratio and the polymerization form (block, random, etc.). In addition, when the polymer block e is composed only of 1,3-butadiene units, the 1,2-bond should be 25% or more in order to prevent performance degradation as a styrene elastomer due to crystallization after hydrogenation. Is preferred.

The bonding mode of the polymer block d and the polymer block e may be linear, branched, radial, or any combination thereof.
When the polymer block d is represented by (d) and the polymer block e is represented by (e), specific examples of the block copolymer (II) include, for example, (d)-(e)-(d) Triblock copolymer, (d)-(e)-(d)-(e) tetrablock copolymer, (d)-(e)-(d)-(e)-(d) And ((d)-(e)) _n X-type polymer (X represents a coupling agent residue, and n represents an integer of 2 or more).
Among these, from the viewpoint of ease of production, a triblock copolymer and a tetrablock copolymer are preferable, and a triblock copolymer is more preferable.

The molecular weight of the block copolymer (II) is preferably in the range of 10,000 to 500,000 in terms of weight average molecular weight, and more preferably in the range of 30,000 to 350,000.
If the weight average molecular weight of block copolymer (II) is in the said range, it is preferable from a viewpoint from which favorable moldability is obtained, and a viewpoint which adjusts residual stress value (alpha) and stress retention to a preferable range.
The glass transition temperature (Tg) of the block copolymer (II) is preferably from −60 ° C. to 40 ° C., more preferably from −50 ° C. to 35 ° C., and from −45 ° C. to 30 ° C. More preferably. When the glass transition temperature is −60 ° C. or higher and 40 ° C. or lower, flexibility can be expressed while maintaining rubber elasticity, and the residual stress value α and the stress retention rate can be adjusted to a preferable range.

From the viewpoint of heat resistance and light resistance, the polymer block e preferably has 50% or more of the carbon-carbon double bonds derived from the conjugated diene hydrogenated, more preferably 80% or more. 90% or more is hydrogenated.
The hydrogenation rate is determined by measuring the content of carbon-carbon double bonds derived from conjugated diene units before and after hydrogenation by iodine value measurement, infrared spectrophotometer, ¹ H-NMR spectrum, etc. It can be obtained from the value.

“Unhydrogenated block copolymer (II)” means that the block based on the conjugated diene is not hydrogenated.
Specific examples of the “unhydrogenated product of the block copolymer (II)” include a styrene-isoprene block copolymer (also referred to as “SIS”), a styrene-butadiene block copolymer (also referred to as “SBS”), and the like. .
The “hydrogenated block copolymer (II)” means that all or a part of the block based on the conjugated diene is hydrogenated.
Specific examples of the “hydrogenated block copolymer” include a hydrogenated styrene-isoprene block copolymer (also referred to as “SEPS”) and a hydrogenated styrene-butadiene block copolymer (also referred to as “SEBS”). Etc.
In the styrenic elastomer, it is preferable to use a hydrogenated product of a block copolymer (II) such as a hydrogenated styrene-butadiene block copolymer (SEBS) and a hydrogenated styrene-isoprene block copolymer (SEPS).

  Commercially available products may be used as the block copolymer (II). For example, the product name “ASAPREN (registered trademark)” series, the product name “TUFTECH (registered trademark)” series, and the product name “TUFPRENE (registered trademark)”. Series (made by Asahi Kasei Chemicals Corporation); trade name TR2003, trade name TR2500, and trade name TR2600 (made by JSR Corporation); trade name Stereon 857 and trade name Stereon 841A (made by Firestone); trade name Clayton D1118; trade name Clayton (registered trademark) G1654 and trade name Clayton (registered trademark) G1726 (manufactured by Clayton Polymer); trade name Sol T166 (manufactured by Enichem); trade name quintack 3433N (Made by Nippon Zeon Co., Ltd.); Emissions (registered trademark) 2002, and the trade name Septon (registered trademark) 2063 (manufactured by Kuraray Co., Ltd.), and the like.

(Olefin elastomer)
Specific examples of the olefin-based elastomer include copolymers of one or more α-olefins, and it is preferable to use a tackifier in combination. The α-olefin copolymer is amorphous. Or low crystallinity is preferable. In addition, the α-olefin copolymer may be used alone or in combination of two or more.
Examples of the α-olefin include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, 4-methylpentene-1, and the like.
Commercially available products may be used as the α-olefin copolymer. Specific examples thereof include trade name “Tafmer (registered trademark)” series, trade name “Notio (registered trademark)” series (manufactured by Mitsui Chemicals, Inc.). ) And the like.

(Tackifier)
In the present embodiment, the pressure-sensitive adhesive layer can further contain a tackifier in addition to the above-described pressure-sensitive adhesive in order to control tackiness.
Specific examples of tackifiers include, for example, acrylic polymers, rosin and derivatives thereof, natural terpene copolymers, three-dimensional polymers of natural terpenes, hydrogenated terpene copolymers, polyterpene resins, and hydrogenated derivatives of phenolic modified terpene resins. , Aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petroleum hydrocarbon resins, cyclic aliphatic petroleum hydrocarbon resins, cyclic aliphatic petroleum carbonized Examples thereof include hydrogenated derivatives of hydrogen resins.
As the tackifier, those having a color tone of colorless to light yellow and having substantially no odor and good thermal stability are preferable, and a liquid type tackifier can also be used.
The tackifier may be used alone or in combination of two or more.

As a tackifier when used in combination with a styrene-based elastomer, a hydrogenated derivative of a cyclic aliphatic petroleum hydrocarbon resin is preferable in view of high compatibility with the styrene-based elastomer, and the hydrogenated derivative is a hydrogenated derivative. A dicyclopentadiene resin is mentioned.
Commercially available products may be used as such tackifiers, for example, trade name Alcon (registered trademark) P100, trade name Alcon (registered trademark) M100 (manufactured by Arakawa Chemical Co., Ltd.); trade name Clearon (registered trademark). M105 (manufactured by Yasuhara Chemical Co., Ltd.); trade name ECR5400, trade name ECR179EX (manufactured by Exxon); trade name Quinton (registered trademark) DX395, and trade name Quinton (registered trademark) DX390N (manufactured by Nippon Zeon Co., Ltd.) It is done.

As a tackifier when used in combination with a (meth) acrylic acid ester elastomer, an acrylic polymer, rosin and its derivatives, etc. are preferable in view of high compatibility with the acrylic base polymer (A). In order to reduce the strain, an acrylic polymer is more preferable because it needs to be a soft adhesive.
Commercially available products may be used as rosin and derivatives thereof, for example, “Pine Crystal (registered trademark)” series, “Superester” series, and “Tamanol (registered trademark)” series (Arakawa Chemical Co., Ltd.). Company-made).

Hereinafter, the acrylic polymer that acts as a tackifier is referred to as an acrylic polymer (B) in distinction from the acrylic base polymer (A) that is an example of the above-described synthetic resin as the adhesive.
(Acrylic polymer (B))
The acrylic polymer (B) has good elastic adhesiveness even when the environmental temperature is low, and the workability is also good, so that the glass transition temperature (Tg) is preferably −30 ° C. or less, It is more preferably −33 ° C. or lower, and further preferably −35 ° C. or lower.
The lower limit value of the glass transition temperature of the acrylic polymer (B) is not particularly limited, but is preferably −90 ° C. or higher from the viewpoint of ease of handling and availability.
When the glass transition temperature is within the above range, the acrylic polymer (B) is easy to handle because it becomes liquid at room temperature.
Moreover, the adhesive force which can be used as an adhesive layer of a pellicle can be expressed by using an acrylic polymer (B). This is presumably because the use of the acrylic polymer (B) improves compatibility with the monomer component having adhesiveness and flexibility contained in the acrylic base polymer (A). Moreover, since the acrylic polymer (B) has a configuration such as pseudo-crosslinking with the acrylic base polymer (A) and has good light resistance, adhesive residue in the pressure-sensitive adhesive layer is suppressed. In addition, the acrylic polymer (B), when used in combination with the acrylic base polymer (A), exhibits flexibility as an adhesive layer, can reduce the residual stress value α, and can increase the stress retention rate. It becomes like this.

The content of the acrylic polymer (B) is preferably 10 to 70 mass%, more preferably 20 to 67 mass%, more preferably 30 to 65 mass%, 50 to 50 mass% with respect to the total mass of the pressure-sensitive adhesive layer. More preferably, it is 65 mass%.
When the content is 10% by mass or more, an appropriate adhesive force can be obtained, and when the content is 70% by mass or less, the cohesive force is set to an appropriate range and the holding force is improved. When the content of the acrylic polymer (B) is within the above range, the pellicle can be prevented from dropping from the mask after being attached to the mask.

The acrylic polymer (B) is preferably a (meth) acrylic acid ester polymer or copolymer from the viewpoint that it can also serve as a softening agent.
The (meth) acrylic acid ester-based polymer or copolymer makes it possible to apply a thick adhesive to the pellicle frame and to further reduce mask distortion when the pellicle is attached to the mask. From the viewpoint of becoming, a block copolymer such as diblock or triblock may be used.
1 type or 2 or more types of C1-C14 (meth) acrylic acid alkyl ester is polymerized, or 1 type, or 2 or more types of C1-C14 (meth) acrylic acid alkyl ester and (meta ) A (meth) acrylic ester polymer or copolymer can be obtained by polymerizing with other monomer components other than the alkyl acrylate ester.
The (meth) acrylic acid ester polymer or copolymer may be used alone or in combination of two or more.

Specific examples of the (meth) acrylic acid alkyl ester having 1 to 14 carbon atoms include (meth) acrylic acid esters of linear aliphatic alcohols and (meth) acrylic acid alkyl esters of branched aliphatic alcohols. , For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, ( Sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, ( Isooctyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate Le, (meth) acrylic acid hydroxypropyl, (meth) glycidyl acrylate include 2-methoxyethyl acrylate and the like.
Among them, compatible with the acrylic base polymer (A) which is an adhesive, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, ( Carbon number 1 such as sec-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, etc. -8 (meth) acrylic acid alkyl esters are preferred.
A C1-C14 (meth) acrylic-acid alkylester may be used by 1 type, or may be used by 2 or more types.

  Other monomer components are not particularly limited as long as they are copolymerizable with a (meth) acrylic acid alkyl ester, and examples thereof include (meth) acrylic acid, vinyl acetate, and styrene.

The molecular weight of the acrylic polymer (B) is preferably in the range of 850 to 70,000 in terms of weight average molecular weight from the viewpoint of easy compatibility with the acrylic base polymer (A), and 900 to 68,000. It is more preferable that it is in the range.
When the weight average molecular weight of the acrylic polymer (B) is 850 or more, sufficient adhesive strength can be obtained, and when it is 70,000 or less, the viscosity can be controlled within an appropriate range and workability can be improved. Can do.
When the weight average molecular weight is within the above range, the tackiness of the acrylic base polymer (A) can be increased. Furthermore, by setting the molecular weight of 800 or less to 18% by mass or less, it is possible to increase the adhesive strength of the pressure-sensitive adhesive layer and improve the adhesive residue.
The molecular weight distribution of the acrylic polymer (B) is preferably M _W / M _N of 1.0 to 2.0 from the viewpoint of preventing adhesive residue.

Commercially available products may be used as the acrylic polymer (B). Specific examples thereof include a trade name “ARUFON (registered trademark)” series (manufactured by Toagosei Co., Ltd.), a trade name “Clarity (registered trademark)” series ( Manufactured by Kuraray Co., Ltd.).
The product name “ARUFON (registered trademark)” series has less impurities because it does not use a polymerization initiator, chain transfer agent, solvent, etc., and its molecular weight distribution is narrow as M _W / M _N is 1.0 to 2.0. Excellent rest prevention.
The product name “Clarity (registered trademark)” series is a triblock copolymer having a hard segment and a soft segment, and is excellent in reducing mask distortion because it can be applied thickly to a pellicle frame. In addition, the product name “Clarity (registered trademark)” series has a narrow molecular weight distribution with M _W / M _N of 1.0 to 2.0, and thus has excellent adhesive residue prevention.

  The (meth) acrylic acid ester-based copolymer may contain a random copolymer in order to impart further adhesive force.

  Moreover, when using a (meth) acrylic acid ester elastomer, a styrene elastomer, and an olefin elastomer as the adhesive of the adhesive layer, a softener such as polybutene may be further contained in the adhesive layer.

(Plasticizer, wax, various additives)
The pressure-sensitive adhesive layer may contain a plasticizer.
The plasticizer is blended for the purpose of lowering the melt viscosity of the pressure-sensitive adhesive layer, imparting flexibility, and improving wettability to the adherend, and is compatible with the block copolymers (I) and (II). If the target adhesive layer can be obtained, there will be no restriction | limiting in particular.
Specific examples of the plasticizer include paraffin oil, naphthenic oil, and aromatic oil. Colorless and odorless naphthenic oil and paraffin oil are preferable.
As the plasticizer, commercially available products may be used. Specific examples thereof include trade name White Oil Broom 350 (manufactured by Kukdong Oil & Chem), trade name Diana Fresia (registered trademark) S32, trade name Diana Process Oil (registered trademark). PW-90, trade name Diana Process Oil (registered trademark) NS-100, trade name DN Oil KP-68 (produced by Idemitsu Kosan Co., Ltd.), trade name KN4010 (produced by Petro China Company), trade name Enperper M1930 (produced by BP Chemicals) ), Trade name Kaydol (registered trademark) (manufactured by Crompton), trade name Primol (registered trademark) 352 (manufactured by Esso), and the like.
In particular, when a styrene elastomer is used for the pressure-sensitive adhesive layer, an appropriate softening can be achieved by adding a plasticizer, and the residual stress value α can be adjusted to a preferred range.

The pressure-sensitive adhesive layer may further contain a wax and various additives as necessary.
The wax is not particularly limited as long as it is an organic substance having a weight average molecular weight of less than 10,000 that is solid at normal temperature and becomes liquid when heated, and can obtain the target pressure-sensitive adhesive layer.
Examples of various additives include stabilizers and fine particle fillers.
The stabilizer is added to improve the stability of the pressure-sensitive adhesive layer by preventing the molecular weight reduction, gelation, coloring, generation of odor, etc. due to heat of the pressure-sensitive adhesive layer. If the target adhesive layer can be obtained, there will be no restriction | limiting in particular.
Examples of the stabilizer include an antioxidant and an ultraviolet absorber.
The antioxidant is used to prevent oxidative deterioration of the pressure-sensitive adhesive layer.
The ultraviolet absorber is used to improve the light resistance of the pressure-sensitive adhesive layer.
Specific examples of the antioxidant include phenolic antioxidants, and examples of the ultraviolet absorber include benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers. A lactone stabilizer may be added to the pressure-sensitive adhesive layer.
As the stabilizer, commercially available products may be used. For example, trade names “Sumilyzer (registered trademark) GM” manufactured by Sumitomo Chemical Co., Ltd., trade names “Smilizer (registered trademark) TPD” and trade names “ "Smilizer (registered trademark) TPS", trade name "Irganox (registered trademark) 1010" manufactured by Ciba Specialty Chemicals, trade name "Irganox (registered trademark) HP2225FF", trade name "Irgafos (registered trademark) 168" and Examples include trade name “Irganox (registered trademark) 1520”, trade name “JF77” manufactured by Johoku Chemical Co., Ltd.
In the case of using a styrene-based elastomer, it is particularly preferable to add such an additive because deterioration due to heat or the like can be prevented.

Each of the plasticizer, wax, and various additives may be used alone or in combination of two or more.

(Crosslinked acrylic resin)
In the pressure-sensitive adhesive layer, a cross-linking pressure-sensitive adhesive may be used as the pressure-sensitive adhesive, and examples of the cross-linking pressure-sensitive adhesive include cross-linked acrylic resins and silicone resins.
By using a resin composition containing a reaction product of a (meth) acrylic acid alkyl ester copolymer and a curing agent as a crosslinkable acrylic resin, the crosslink density can be adjusted, and the residual stress value α can be adjusted. It can be adjusted to a preferred range.
In general, the higher the crosslink density, the larger the residual stress value α and the maximum stress value. The residual stress value α and the maximum stress value α _max can also be adjusted by adjusting the Tg of the resin contained in the adhesive layer. Generally, the higher the Tg, the larger the residual stress value α and the maximum stress value α _max tend to be. Moreover, since the residual stress value is less relaxed as the crosslink density and Tg are higher, the stress retention rate tends to increase.

The (meth) acrylic acid alkyl ester copolymer is a monomer having a functional group having reactivity with a C 1-14 (meth) acrylic acid alkyl ester (hereinafter referred to as “component A”) and a curing agent ( Hereinafter, a copolymer obtained by copolymerizing two or more monomer components with “B component”) has a sufficient adhesive force with a mask and has little adhesive residue after peeling. To preferred.
The (meth) acrylic acid alkyl ester copolymer is a copolymer of a monomer mixture in which the A component is 80 to 99% by mass and the B component is 1 to 20% by mass. From the viewpoint of

The A component has a linear alkyl group having 1 to 14 carbon atoms (hereinafter referred to as “component A1”) and a branched alkyl group having 3 to 14 carbon atoms (hereinafter referred to as “component A2”). In this case, the (meth) acrylic acid alkyl ester copolymer is preferably a copolymer of a monomer mixture having an A2 component of 9 to 59% by mass because the adhesive strength is excellent.
A copolymer of a monomer mixture in which the A1 component is 40 to 90% by mass, the A2 component is 9 to 59% by mass, and the B component is 1 to 20% by mass is preferable because the adhesive residue after peeling is reduced.

Examples of the straight chain alkyl group (meth) acrylate alkyl ester having 1 to 14 carbon atoms as the A1 component include, for example, butyl (meth) acrylate, hexyl (meth) acrylate, and octyl (meth) acrylate. And (meth) acrylic acid esters of linear aliphatic alcohols such as decyl (meth) acrylate, dodecyl (meth) acrylate, and lauryl (meth) acrylate.
A1 component may be used by 1 type, or may be used by 2 or more types.
Among them, since (meth) acrylic acid alkyl ester having 4 to 14 carbon atoms, preferably 4 to 8 carbon atoms such as butyl (meth) acrylate and octyl (meth) acrylate, exhibits appropriate adhesion to the mask, preferable.
In the case of (meth) acrylic acid alkyl ester having a linear alkyl group having 1 to 3 carbon atoms, which is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, component A2 and component B When the copolymer is made, the steric hindrance of the carboxyl group contributing to the adhesiveness of the B component is reduced, and the adhesiveness is improved.

Examples of the branched alkyl group (meth) acrylic acid alkyl ester having 3 to 14 carbon atoms as the A2 component include isopropyl (meth) acrylate, isobutyl (meth) acrylate, isopentyl (meth) acrylate, Examples include (meth) acrylic acid esters of branched chain aliphatic alcohols such as 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl (meth) acrylate.
A2 component may be used by 1 type, or may be used by 2 or more types.
Among these, from the viewpoint of copolymerization, isobutyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferably used.

The monomer of B component is a monomer copolymerizable with the C1-C14 (meth) acrylic-acid alkylester of A component, and is a monomer which has the reactivity with a hardening | curing material.
Examples of the B component monomers include carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, and crotonic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, It is a hydroxyl group-containing monomer such as (meth) acrylic acid 2-hydroxypropyl and (meth) acrylic acid 4-hydroxybutyl.
The monomer of component B may be used alone or in combination of two or more.
Among these, from the viewpoints of copolymerizability, versatility, etc., a hydroxyl group containing a hydroxyalkyl group having 2 to 4 carbon atoms such as 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate (meta ) Carboxyl group-containing monomers such as acrylic acid alkyl esters and (meth) acrylic acid are preferably used. (Meth) acrylic acid is more preferable from the viewpoint of adhesive residue.
The (meth) acrylic acid is preferably contained in an amount of 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, based on all monomers constituting the (meth) acrylic acid alkyl ester copolymer. It is more preferable to contain 0.8-3 mass%.

In the (meth) acrylic acid alkyl ester copolymer, the A1 component is preferably 40 to 90% by mass, more preferably 45 to 80% by mass, and the A2 component is preferably 9 to 59% by mass in the monomer mixture. Preferably 15-50 mass%, B component is 1-20 mass%, Preferably it is used in the ratio of 2-10 mass%.
When the molecular weight of the (meth) acrylic acid alkyl ester copolymer is in the range of 700,000 to 2.5 million as the weight average molecular weight, the cohesive force and adhesive force of the pressure-sensitive adhesive layer become appropriate, and the adhesive remains. It is difficult to form a pressure-sensitive adhesive having sufficient adhesive strength and load resistance.
The weight average molecular weight is more preferably in the range of 900,000 to 2,300,000, and further preferably in the range of 1,000,000 to 2,000,000.
About the control method of a weight average molecular weight, it can control by a well-known method. Specifically, the weight average molecular weight tends to increase as the monomer concentration during the polymerization reaction generally increases, and the weight average molecular weight tends to increase as the polymerization initiator amount decreases. It is in. In general, the cohesive force increases as the weight average molecular weight increases, and the residual stress value α and the maximum stress value α _max tend to increase as the cohesive force increases.

  In this embodiment, the production of the (meth) acrylic acid alkyl ester copolymer can be appropriately selected from known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the obtained (meth) acrylic acid alkyl ester copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used.
Examples of the polymerization initiator include azo-based 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis ( 2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2- Methylbutyronitrile), 4,4′-azobis (4-cyanovaleric acid) and the like, peroxide-based dibenzoyl peroxide, dilauroyl peroxide and the like.

  In this embodiment, the cross-linked acrylic resin used as the pressure-sensitive adhesive for the pressure-sensitive adhesive layer comprises a resin composition containing a reaction product of a (meth) acrylic acid alkyl ester copolymer and a curing agent. However, in consideration of softness, a resin composition containing a reaction product containing no curing agent may be used.

The curing agent is not particularly limited as long as it is a curing material used as a normal pressure-sensitive adhesive. For example, metal salts, metal alkoxides, aldehyde compounds, non-amino resin amino compounds, urea compounds, isocyanate compounds, Examples include polyfunctional epoxy compounds, metal chelate compounds, melamine compounds, and aziridine compounds.
Among these, from the viewpoint of reactivity with the functional group component of the (meth) acrylic acid alkyl ester copolymer, the curing agent is preferably an isocyanate compound or a polyfunctional epoxy compound, and more preferably a polyfunctional epoxy compound. .

Specific examples of the isocyanate compound include tolylene diisocyanate.
Specific examples of the polyfunctional epoxy compound include neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, phthalic acid diglycidyl ester, dimer acid diglycidyl ester, Triglycidyl isocyanurate, diglycerol triglycidyl ether, sorbitol tetraglycidyl ether, N, N, N ′, N′-tetraglycidyl m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane and the like can be mentioned.
Especially, the nitrogen-containing epoxy compound which has 2-4 epoxy groups is preferable, and the nitrogen-containing epoxy compound which has 4 epoxy groups is more preferable from a reactive point.
If the reactivity is good, the cross-linking reaction is completed quickly after application as a pressure-sensitive adhesive layer, so that the characteristics are stabilized in a short time and the productivity is excellent.
Further, the residual stress value α and the stress retention rate can be adjusted by appropriately adjusting the content of the curing agent.

By the way, the polymerization initiator remaining in the pressure-sensitive adhesive layer is preferably 8 ppm or less with respect to the total mass of the pressure-sensitive adhesive layer. Generation | occurrence | production of the haze of a photomask can be suppressed significantly because the polymerization initiator which remains in an adhesive layer is 8 ppm or less with respect to the adhesive layer total mass.
Although it is not clear why the haze of the photomask is improved by reducing the amount of the polymerization initiator remaining in the pressure-sensitive adhesive layer, it is considered as follows.
There are several possible causes of haze, but the main cause of haze is that the organic gas component present in the exposure atmosphere causes a chemical reaction due to the energy of the exposure light, and the reaction product adheres to the photomask. It is thought that. If a certain amount of polymerization initiator is present in the pressure-sensitive adhesive layer, the polymerization initiator is cleaved by the energy of the exposure light, triggering a chemical reaction of the organic gas, resulting in the formation of a reaction product that causes haze. I guess the amount will be much higher.
For the above reasons, the polymerization initiator remaining in the pressure-sensitive adhesive layer used for the pellicle is preferably 8 ppm or less, more preferably 7 ppm or less, and more preferably 6 ppm or less, based on the total mass of the pressure-sensitive adhesive layer. Is more preferable.

  For the method of reducing and controlling the polymerization initiator remaining in the pressure-sensitive adhesive layer, use a polymerization initiator that reduces the amount of polymerization initiator when polymerizing (meth) acrylic acid alkyl ester copolymers or is easily thermally decomposed. In addition, there may be mentioned a method of applying a high temperature for a long time in the application / drying step of the pressure-sensitive adhesive layer and decomposing the polymerization initiator in the drying step.

An index representing the thermal decomposition rate of the polymerization initiator is a 10-hour half-life temperature.
The 10-hour half-life temperature means a temperature at which the half-life, which is the time until the polymerization initiator decomposes by half of the original amount, becomes 10 hours.
Since the polymerization initiator having a lower 10-hour half-life temperature is more likely to be thermally decomposed, it is less likely to remain in the pressure-sensitive adhesive layer.
It is suitable to use a polymerization initiator having a 10-hour half-life temperature of preferably 80 ° C. or lower, more preferably 75 ° C. or lower.
As such a polymerization initiator, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (10 hour half-life temperature 30 ° C.), 2,2′-azobisisobutyronitrile ( 10-hour half-life temperature 60 ° C.), 2,2′-azobis (2,4-dimethylvaleronitrile) (10-hour half-life temperature 51 ° C.), dimethyl 2,2′-azobis (2-methylpropionate) ( 10-hour half-life temperature 66 ° C.), 2,2′-azobis (2-methylbutyronitrile) (10-hour half-life temperature 67 ° C.), dibenzoyl peroxide (10-hour half-life temperature 74 ° C.), dilauroyl par And oxide (10 hour half-life temperature 62 ° C.).

A photopolymerization initiator may be used as the polymerization initiator.
Examples of a method for reducing and controlling the photopolymerization initiator remaining in the pressure-sensitive adhesive layer include a method of thermal decomposition, drying and evaporation by heating, a method of irradiating ultraviolet rays and decomposing the photopolymerization initiator.
Examples of such photopolymerization initiators include alkylphenone polymerization initiators and acylphosphine oxide polymerization initiators.
Examples of the alkylphenone polymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- ( 2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl ] -1- [4- (4-morpholinyl) phenyl] -1-butanone and the like.
Examples of the acylphosphine oxide polymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and the like.

In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent.
As a specific example of solution polymerization, the reaction is carried out under an inert gas stream such as nitrogen, as a polymerization initiator, for example, azobisisobutyronitrile 0.01 to 2.0 with respect to 100 parts by mass of the total amount of monomers. Addition of parts by mass is usually performed at about 50 to 70 ° C. for about 8 to 30 hours.

  The pressure-sensitive adhesive layer may further contain conventionally known additives such as a filler, a pigment, a diluent, an anti-aging agent, and an ultraviolet stabilizer as necessary. These additives can be used alone or in combination of two or more. However, the addition amount is preferably set as appropriate so that desired physical properties can be obtained.

(Pellicle manufacturing method)
The pellicle of this embodiment can be suitably manufactured by the following method, for example.
First, a styrene-based elastomer, a (meth) acrylic acid ester-based elastomer, an olefin-based elastomer, or the like is mixed with a plasticizer or other additives as necessary to obtain a pressure-sensitive adhesive composition.
In order to form (apply) the pressure-sensitive adhesive layer 10 on the end face of the pellicle frame 2 as a pressure-sensitive adhesive layer having a desired thickness and width, the pressure-sensitive adhesive composition is further diluted with a solvent to adjust the solution concentration (viscosity).

Second, the pressure-sensitive adhesive composition is applied to the other end surface 2f of the pellicle frame 2 having the pellicle film 3 stretched on the one end surface 2e. The application method is not particularly limited, but when the adhesive composition is diluted with a solvent, it is preferably applied using a dispenser or a syringe. Moreover, you may use the hot-melt method which heat-melts and apply | coats an adhesive composition.
The pellicle film 3 may be attached (stretched) to the pellicle frame 2 either before or after the formation of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive composition is applied to the other end surface 2f of the pellicle frame 2 and then the pressure-sensitive adhesive layer. Then, the pellicle film 3 may be attached to the one end surface 2e of the pellicle frame 2.

Third, when the pressure-sensitive adhesive composition is diluted with a solvent, the applied pressure-sensitive adhesive composition is dried by heating. When the pressure-sensitive adhesive composition is applied by the hot melt method, the applied pressure-sensitive adhesive composition is cooled after being heat-molded.
After drying or cooling the pressure-sensitive adhesive composition, a protective film F for protecting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer 10 is applied to the surface of the pressure-sensitive adhesive layer (the surface on the side opposite to the pellicle frame and the surface to be later attached to the mask). It may be pasted. As the protective film F, for example, a polyester film having a thickness of 30 to 200 μm is used. Moreover, when the peeling force at the time of peeling off the protective film F from the adhesive layer 10 is large, there exists a possibility that the adhesive layer 10 may deform | transform at the time of peeling. Therefore, a release treatment using silicone or fluorine may be performed in advance on the surface of the protective film F in contact with the pressure-sensitive adhesive layer 10 so as to obtain an appropriate peeling force.
After the protective film F for protecting the adhesive surface of the pressure-sensitive adhesive layer 10 is pasted, the surface of the pressure-sensitive adhesive layer may be formed substantially flat by applying a weight.

Moreover, the pellicle of this embodiment can be suitably manufactured, for example with the following method, when using a (meth) acrylic-acid alkylester copolymer as an adhesive of an adhesive layer.
First, a (meth) acrylic acid alkyl ester copolymer and a curing agent or a curing agent solution are mixed to obtain a pressure-sensitive adhesive precursor composition. In this case, in order to apply a mask pressure-sensitive adhesive layer having a desired thickness and width, the pressure-sensitive adhesive precursor composition can be further diluted with a solvent to adjust the solution concentration (viscosity). The solvent for dilution is selected from the viewpoints of solubility, evaporation rate and the like. Preferred solvents include, for example, acetone, ethyl acetate, toluene and the like, but are not limited thereto.

Second, the pressure-sensitive adhesive precursor composition is applied to the other end surface 2f of the pellicle frame 2 having the pellicle film 3 stretched on the one end surface 2e. The application method is not particularly limited, but it is preferable to apply using a dispenser. The viscosity of the acrylic copolymer solution in the above-mentioned pressure-sensitive adhesive precursor composition (referring to a solution comprising a solvent and a (meth) acrylic acid alkyl ester copolymer) is not particularly limited, but is preferably 50 P or less, more preferably Is a viscosity of about 10 to 40 P, more preferably about 20 to 30 P (B-type viscometer, 25 ° C.).
By diluting with a solvent in application with a dispenser, there is little stringing of the coating liquid, and it becomes easy to adjust to a stable width and thickness.

Thirdly, the solvent and / or residual monomer can be removed by heating and drying the applied pressure-sensitive adhesive layer. Further, when the functional group of the (meth) acrylic acid alkyl ester copolymer and the curing agent are reacted by heating to form a crosslinked structure, the pellicle frame 2 and the pressure-sensitive adhesive composition are integrated, and the pellicle frame 2 has a surface. The pressure-sensitive adhesive layer 10 adheres.
The drying temperature is preferably 50 to 200 ° C. and more preferably 60 to 190 ° C. in consideration of the boiling point of the solvent and residual monomer and the decomposition temperature of the (meth) acrylic acid alkyl ester copolymer. .
You may stick the protective film F (release sheet) for protecting an adhesive surface after drying and bridge | crosslinking.
The pellicle film 3 may be attached (stretched) to the pellicle frame 2 either before or after the formation of the pressure-sensitive adhesive layer. After the pressure-sensitive adhesive layer 10 is provided on the other end surface 2f of the pellicle frame 2, the pellicle frame 3 is attached. Alternatively, the pellicle film 3 may be affixed to the one end face 2e.

  The thickness of the pressure-sensitive adhesive layer is preferably 0.2 mm or greater and 3.0 mm or less. For semiconductors, 0.2 mm or more and 1.0 mm or less is preferable, 0.25 mm or more and 0.8 mm or less is more preferable, and 0.3 mm or more and 0.7 mm or less is more preferable. For liquid crystals, 0.8 mm to 3.0 mm is preferable, 1.0 mm to 2.5 mm is more preferable, and 1.2 mm to 2.0 mm is further preferable.

The surface of an aluminum material generally used as a pellicle frame may have fine irregularities. The adhesive layer, which is more flexible than the pellicle frame, absorbs the irregularities so that the surface of the aluminum material is irregular. It is possible to obtain the flatness of the mask without being affected by the above.
If the thickness of the pressure-sensitive adhesive layer is within the above range, the unevenness of the surface of the pellicle frame can be absorbed, and the outgas from the pressure-sensitive adhesive layer is at a level where there is no problem while ensuring the flatness of the mask. A pellicle with reduced mask distortion can be obtained.

  The protective film F used in the present embodiment is generally a film having a thickness of about 30 to 200 μm such as polyester. Moreover, since the adhesive layer 10 may be deformed when peeling when the protective film F is peeled off from the pressure-sensitive adhesive layer 10, the film surface in contact with the pressure-sensitive adhesive so as to have an appropriate peeling force. In addition, a mold release treatment such as silicone or fluorine may be performed. After sticking the protective film F for protecting the adhesive surface, the pressure-sensitive adhesive surface may be formed substantially flat by applying a weight.

(Pellicle frame, pellicle film)
In the present embodiment, a conventionally known pellicle frame having a rectangular shape can be used after being subjected to a surface treatment such as anodizing or painting. In order to increase the flatness of the pressure-sensitive adhesive layer, it is preferable to increase the flatness in the cross-sectional direction and the circumferential direction in advance by heat treatment or load heat treatment on the pellicle frame.
Moreover, there is no limitation also about a pellicle film and its extending | stretching method, A conventionally well-known thing and method can be used.

  Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited thereto.

Each measurement method and evaluation method in the present embodiment are as follows.
(1) Measurement of flatness (μm) in the cross-sectional direction of the pressure-sensitive adhesive layer Slowly peel off the protective film of the pellicle with protective film so that the shape of the pressure-sensitive adhesive layer does not change, and place the pellicle film surface on the base of the laser displacement meter Installed down.
The height of the cross section obtained when cutting in a direction perpendicular to the direction parallel to the side of the pellicle frame, with a total of 12 points of the center 4 points of each side and 8 points 20 mm to the left and right of the point. Actually, measurement was performed with a laser displacement meter without cutting, and a value (level difference) was calculated by subtracting the lowest value from the highest value for each point.
The average of the values for the 12 points obtained was determined, and this was taken as the flatness in the width direction.

(2) Measurement of the flatness (μm) in the circumferential direction of the pressure-sensitive adhesive layer Slowly peel off the protective film of the pellicle with protective film so that the shape of the pressure-sensitive adhesive layer does not change, and place the pellicle film surface on the base of the laser displacement meter Installed down.
When the adhesive layer is cut at the center of its width parallel to the side of the pellicle frame, the height is measured at a total of 8 points, 4 points at the center of each side and 4 points at the corners. Was actually measured without cutting the adhesive layer, and a value obtained by subtracting the lowest value from the highest value was obtained.

(3) Measurement of residual stress value α (N / mm ² ) after relaxation by 20% elongation / 24 hours Cut the pellicle with protective film, cut out one side, and stick from the pressure-sensitive adhesive layer provided on the cut out side The protective film was slowly peeled off so that the agent layer was not deformed, and then the pressure-sensitive adhesive layer was slowly peeled off from the pellicle frame. At that time, when it was difficult to peel off, the sticker roll was slowly peeled while adhering to the hand and the pressure-sensitive adhesive layer, and the elongation rate in the longitudinal direction of the peeled pressure-sensitive adhesive layer was adjusted to 5% or less.
About the peeled adhesive layer, the tensile stress (N) was measured with the following apparatus.
Device name: Autograph (SHIMAZU EZ-S manufactured by Shimadzu Corporation)
Load cell: 1N (clip type chuck)
Between chucks: 40mm
Crosshead speed: 100mm / min
Specifically, with the above apparatus, the pressure-sensitive adhesive layer was pulled in the longitudinal direction to an elongation of 20%, the crosshead was stopped and relaxed, and the tensile stress (N) after 24 hours was measured.
Separately, the cross-sectional area (mm ² ) of the pressure-sensitive adhesive layer is measured, and the tensile stress (residual stress) (N) after relaxation for 24 hours obtained as described above is divided by the cross-sectional area (mm ² ). The residual stress value α (N / mm ² ) after relaxation for 24 hours per unit area was determined.
Further, the stress retention rate (= α / α _max × 100) (%) was determined from the maximum stress value α _max when extended to 20% and the residual stress value α when relaxed for 24 hours thereafter.
The cross-sectional area of the pressure-sensitive adhesive layer was measured as follows.
From the pellicle with the protective film, cut one side different from the side previously cut out for measuring the tensile stress, and then slowly peel off the protective film so that the pressure-sensitive adhesive layer is not deformed. The layer was removed. Next, this was cut into a length of about 1 cm perpendicular to the longitudinal direction of the pressure-sensitive adhesive layer (side direction of the pellicle frame), embedded in resin, and the resin was naturally cured. Then, the cross section was polished with a polishing machine, and then the shape was measured with a microscope to calculate the cross sectional area. In addition, when a protective film is easy to cut | disconnect, you may measure the cross-sectional area of an adhesive layer with a protective film.

(4) Mask Strain Evaluation Mask strain evaluation was measured using a FlatMaster 200 manufactured by Tropel. First, the flatness of the mask (6025 quartz) before attaching the pellicle was measured. Thereafter, the pellicle was attached to the mask using a simple mounter (weight: 5 Kgf, 45 sec), and the flatness of the mask after the pellicle was attached was measured (measurement range: 135 mm × 110 mm).
The flatness before and after pasting was subtracted, and how much the mask was deformed by pasting the pellicle was calculated.
A: Deformation of the mask due to pasting of the pellicle is 25 nm or less. Δ: Deformation of the mask due to pasting of the pellicle is over 25 nm to 45 nm or less. X: Deformation of the mask due to pasting the pellicle exceeds 45 nm.

(5) Bubble evaluation The pellicle was affixed to a mask (6025 quartz) using a simple mounter (weight: 5 Kgf, 45 sec), and stored in a clean room for 3 days with the pellicle facing down. After 3 days, check if there is any air bubble between the pressure-sensitive adhesive layer and the mask from the mask side (the mask material 6025 quartz is transparent, so the part where the pressure-sensitive adhesive layer is stuck or between the sticking part and the mask The bubbles generated in the film can be visually confirmed).
○: No air bubbles Δ: Air bubbles are generated, and the area of the generated part is 5% or less with respect to the entire area (area of the entire width of the pressure-sensitive adhesive layer). More than%

<Example 1>
Ethyl acetate (30 parts by mass) was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. Mixture (32 masses) of isobutyl acrylate / butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate / 2, 2'-azobisisobutyronitrile mixed at a mass ratio of 30/66 / 1.5 / 2.5 / 1 Part) was added to ethyl acetate and allowed to react at 60 ° C. for 8 hours under a nitrogen atmosphere. After completion of the reaction, toluene (38 parts by mass) was added to the reaction solution to obtain an acrylic copolymer solution having a nonvolatile concentration of 32% by mass (weight average molecular weight 1.3 million).
0.15 parts by mass of polyfunctional epoxy compound (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane in toluene solution, nonvolatile concentration 5%) was added to 100 parts by mass of the obtained acrylic copolymer. -It stirred and mixed and the adhesive precursor composition was obtained.
An anodized aluminum alloy pellicle frame (outer diameter 113 mm × 149 mm, inner diameter 109 mm × 145 mm, height 3.2 mm, flatness on the mask side of the frame was 13 μm) was prepared. The pellicle frame has a hole diameter at a position that is 1.7 mm from the end surface on which the pellicle film is stretched as a pin hole for easy handling, and at a position that is 25 mm from the corner portion on the outer side surface of the pellicle frame. Four jig holes with 1.6 mmφ and 1.2 mm depth were provided.
The obtained pressure-sensitive adhesive precursor composition was applied onto one end surface of the pellicle frame with a dispenser. This was heated, dried, molded and cured in two stages on a high-definition molding machine (first stage: 100 ° C., 8 minutes, second stage: 180 ° C., 8 minutes) to form an adhesive layer. .
Thereafter, a polyester protective film having a thickness of 100 μm, which was subjected to silicone release treatment, was bonded to the surface of the pressure-sensitive adhesive layer and cured to stabilize the pressure-sensitive adhesive force. The thickness of the formed pressure-sensitive adhesive layer was 0.3 mm.
Next, a pellicle film was attached to the other end surface of the pellicle frame using an adhesive to produce a pellicle.
When the flatness of the pressure-sensitive adhesive layer was measured for the obtained pellicle, the flatness in the cross-sectional direction was 7.5 μm, the flatness in the circumferential direction was 10 μm, and the cross-sectional shape of the pressure-sensitive adhesive layer was outside>inside> center It was expensive in part order.
The obtained pellicle was subjected to measurement of residual stress value α after relaxation of 20% elongation / 24 hours, evaluation of mask distortion, and evaluation of bubbles after application. The results are shown in Table 1.

<Example 2>
A pressure-sensitive adhesive precursor composition was obtained in the same manner as in Example 1 except that the addition amount of the polyfunctional epoxy compound of Example 1 was 0.3 parts by mass. Next, a pellicle was produced in the same manner as in Example 1, and the flatness and evaluation were measured. The results are shown in Table 1. The cross-sectional shape of the pressure-sensitive adhesive layer was higher in the order of outer side> center portion> inner side.
<Example 3>
The same pellicle frame as in Example 1 was prepared, and the same pressure-sensitive adhesive precursor composition as in Example 1 was applied to one end surface of the pellicle frame with a dispenser. This is sandwiched between ceramic plates with a flatness of 2 μm or less, and dried, molded, and cured in two stages (first stage: 100 ° C., 8 minutes, second stage: 180 ° C., 8 minutes), and an adhesive layer Formed.
Thereafter, a polyester protective film having a thickness of 100 μm subjected to silicone release treatment was bonded to the surface of the pressure-sensitive adhesive layer and cured to stabilize the pressure-sensitive adhesive force.
A pellicle was produced in the same manner as in Example 1, and the flatness and evaluation were measured. The results are shown in Table 1. The cross-sectional shape of the pressure-sensitive adhesive layer was higher in the order of outer side> center part> middle side.
<Example 4>
65 parts by mass of “UP1080 (manufactured by Toagosei Co., Ltd.)” as a tackifier and 35 parts by mass of “Clarity LA2330 (manufactured by Kuraray Co., Ltd.)” as an adhesive are mixed to a total of 48 g. A mixture was obtained. The obtained raw material mixture was put into a lab plast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd., internal volume: 60 mL) and then sealed. It knead | mixed for 20 minutes at 200 degreeC and 100 rpm, and obtained the block-shaped adhesive composition. About 10 g of the pressure-sensitive adhesive composition was charged into a heating tank (tank temperature: 200 ° C.) and melted.
An anodized aluminum alloy pellicle frame (outer diameter 113 mm × 149 mm, inner diameter 109 mm × 145 mm, height 2.9 mm) was prepared. The pellicle frame has a hole diameter of 1.6 mmφ and a depth of 1.7 mm from the end surface on which the pellicle film is stretched as a pin hole and at a position of 25 mm from the corner portion on the outer side surface of the pellicle frame. Four 1.2 mm jig holes were provided.
A molten pressure-sensitive adhesive composition extruded from a needle tip communicating with a heating tank is applied onto one end face of a pellicle frame, and this is heated, dried, molded, and cured (1 Step: 150 ° C., 10 minutes, second step: 180 ° C., 10 minutes) to form an adhesive layer.
Thereafter, a polyester protective film having a thickness of 100 μm, which was subjected to silicone release treatment, was bonded to the surface of the pressure-sensitive adhesive layer and cured to stabilize the pressure-sensitive adhesive force. The thickness of the formed adhesive layer was 0.6 mm.
Thereafter, a pellicle film was attached to the other end surface of the pellicle frame using an adhesive to produce a pellicle.
About the obtained pellicle, the pellicle was produced similarly to Example 1, and flatness and evaluation were measured. The results are shown in Table 1. The cross-sectional shape of the pressure-sensitive adhesive layer was higher in the order of outer side> inner side> center part.
<Comparative Example 1>
23.1 parts by mass of “UP1080 (manufactured by Toagosei Co., Ltd.)” and 25.6 parts by mass of “Pine Crystal KE311 (manufactured by Arakawa Chemical Industries, Ltd.)” as a tackifier, and “Clarity LA2410e (Kuraray Co., Ltd.) as an adhesive. The pellicle was prepared in the same manner as in Example 4 except that 51.3 parts by mass of the product was used and the molding conditions in the high-definition molding machine were changed, and the flatness and evaluation were measured. The results are shown in Table 1. The cross-sectional shape of the pressure-sensitive adhesive layer was higher in the order of outer side> center portion> inner side.
<Comparative example 2>
A pressure-sensitive adhesive precursor composition was obtained in the same manner as in Example 2. A pellicle was produced in the same manner as in Example 1 except that the molding conditions in the high-definition molding machine were changed, and the flatness and evaluation were measured. The results are shown in Table 1. The cross-sectional shape of the pressure-sensitive adhesive layer was higher in the order of the central part> inner side> outer side.

  The pellicle of the present invention can be suitably used in photolithography processes such as IC (integrated circuit), LSI (large scale integrated circuit), LCD (liquid crystal display). In particular, the pellicle of the present invention can be suitably used in a photolithography process using an excimer laser used in exposure requiring high resolution, preferably in a photolithography process using ultraviolet light exposure of 200 nm or less.

DESCRIPTION OF SYMBOLS 1 Pellicle 2 Pellicle frame 2e, 2f End surface of pellicle frame 3 Pellicle film 10 Adhesive layer F Protective film.

Claims (5)

A pellicle frame;
A pellicle film stretched on one end surface of the pellicle frame;
An adhesive layer attached to the other end surface of the pellicle frame,
The pellicle whose flatness of the cross-sectional direction of the said adhesive layer is 20 micrometers or less.   The pellicle according to claim 1, wherein the adhesive layer has a circumferential flatness of 15 µm or less.   When the cross-sectional shape that appears when the pressure-sensitive adhesive layer is cut in a direction perpendicular to the direction parallel to the side of the pellicle frame is observed at any 12 points, the outer height is 6 points or more, The pellicle according to claim 1 or 2, wherein the pellicle has a shape that is higher than the height of the inner or central portion. The pellicle according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a residual stress value after 20% elongation / 24-hour relaxation of 1.0 mN / mm ² or more and 12.0 mN / mm ² or less.   The pellicle according to any one of claims 1 to 4, wherein a difference in height in a cross section that appears when the adhesive layer is cut at an angle of 45 degrees at each corner is 10 µm or less.