JP2016156882A - Pellicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pellicle capable of reducing mask strain when crimped to a mask.SOLUTION: There is provided a pellicle comprising: a pellicle frame; a pellicle film which is provided on one end face of the pellicle frame; and an adhesive layer adhered to the other end face of the pellicle frame. The adhesive layer has a residual stress value after 20% extension/24 hours relaxing, of 1.0 mN/mmor more and 12.0 mN/mmor less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pellicle.

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.

  On the other hand, the pellicle has a structure in which a transparent thin film is stretched on one end surface of a pellicle frame having a frame shape. By fixing the pellicle on the mask, foreign matter directly adheres to the mask, It prevents the formation of defects. Specifically, even if foreign matter adheres to the pellicle in the photolithography process, the foreign matter does not form an image on the wafer coated with the photoresist. As a result, it is possible to prevent a short circuit and disconnection of the semiconductor integrated circuit due to a circuit pattern defect caused by an image of a foreign substance, and to improve the manufacturing yield of the photolithography process.

As a method of fixing the pellicle on the mask, a method of fixing the pellicle in a peelable manner with an adhesive is usually used. Known adhesives such as acrylic, rubber, polybutene, polyurethane, and silicone adhesives are known.
For the purpose of providing a pellicle having a good load resistance and an excellent mask flatness by the present inventors in Patent Document 1, the stress relaxation property of the pressure-sensitive adhesive layer of the pellicle has a specific value. Is disclosed.

JP 2013-134481 A

One factor that impairs the flatness of the mask is that mask distortion occurs when a pellicle is attached to the mask. As one of the causes of mask distortion, it is considered that when a pellicle is pressure-bonded to a mask via an adhesive layer, the distortion of the pellicle frame is transmitted to the mask through the adhesive layer.
Therefore, in order not to transmit the distortion of the pellicle frame to the mask, the pressure-sensitive adhesive layer softens and deforms, thereby relaxing the distortion energy of the pellicle frame and consequently reducing the mask distortion. A layer is desired.
In addition, in order to cope with oblique incidence due to further miniaturization and liquid immersion exposure in recent years, the demand for mask distortion reduction has become strict, and a pellicle meeting that demand is still desired.
The problem to be solved by the present invention is to provide a pellicle with reduced mask distortion when it is pressure-bonded to the mask.

  As a result of intensive studies by the present inventors, it has been found that the above-mentioned problems can be solved by setting the residual stress value after 20% elongation / 24-hour relaxation of the pressure-sensitive adhesive layer of the pellicle to a specific range. Was 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 pressure-sensitive adhesive layer is a pellicle having a residual stress value after relaxation of 20% elongation / 24 hours of 1.0 mN / mm ^{2 to} 12.0 mN / mm ² .
(2)
The pellicle according to (1), wherein the adhesive layer has a stress retention of 42% or more.
(3)
The elastic modulus of the adhesive layer is 20 mN / mm ² or more 180mN / mm ² or less, pellicle according to (1) or (2).
(4)
The pellicle according to any one of (1) to (3), wherein the pressure-sensitive adhesive layer contains an acrylic resin or a synthetic rubber resin.

  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 surface of the pellicle frame, and an adhesive layer attached to the other end surface of the pellicle frame,
The pressure-sensitive adhesive layer has a residual stress value after relaxation of 20% elongation / 24 hours of 1.0 to 12.0 mN / mm ² .
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.

The pellicle of this embodiment includes an adhesive layer having a residual stress value after relaxation of 20% elongation / 24 hours of 1.0 to 12.0 mN / mm ² attached to the other end surface of the pellicle frame.
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.

It is said that it takes about 24 hours for the pellicle-attached mask to be affixed to the mask and stabilized. Conventionally, only the mask deformation immediately after pasting was considered, but if the inventors pursue further reduction of mask distortion, if the residual stress after pasting stability is small, the residual stress immediately after pasting It was also found that it is preferable because the force for deforming the mask from immediately after to after stabilization becomes small.
Therefore, in the present embodiment, it is possible to reduce the mask distortion by focusing on the residual stress after the sticking is stabilized and setting the residual stress value α to a specific range. The larger the numerical value, the larger the residual stress, and the stronger the force for deforming the mask, the larger the mask distortion. For this reason, the smaller the numerical value, the smaller the force for deforming the mask, but there is a possibility that the mask and the pellicle are displaced when the mask is stored.
In the present embodiment, by setting the residual stress value α within the range of 1.0 to 12.0 mN / mm ² , the mask distortion is reduced, and the mask and pellicle are not displaced during mask storage. I found it.
Residual stress value alpha, is 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 preferably at 5.5mN / mm ² or more 9.0mN / mm ² or less, and more 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.

In the present embodiment, the adhesive layer preferably has a higher stress retention rate, preferably 42% or more, and more preferably 45% or more.
High stress retention means that the pressure-sensitive adhesive layer is hardly deformed immediately after being attached to the mask and after 24 h, and mask strain can be reduced by the stress retention being within the above range.
In the present embodiment, the stress retention rate means a value calculated as α / α _max × 100 from the maximum stress value α _max at 20% elongation and the residual stress value α.
When the stress retention is 42% or more, it also means that the stress of the adhesive is hardly applied to the mask.
In the present embodiment, the “maximum stress value at 20% elongation” means the maximum stress value α _max when the adhesive layer is elongated by 20%.

In the present embodiment, the measurement of the maximum stress value α _max at 20% elongation and the residual stress value α when relaxed for 24 hours after 20% elongation is performed by cutting one side of the pellicle with a protective film, and then adhesive. The protective film is slowly peeled off so that the layer is not deformed, and then the pressure-sensitive adhesive layer peeled off slowly from the pellicle frame can be measured as a sample.

In this embodiment, the elastic modulus of the adhesive layer is preferably at 20 mN / mm ² or more 180mN / mm ² or less. If the elastic modulus of the pressure-sensitive adhesive is within this range, it is preferable because the peel strength becomes appropriate and the pressure-sensitive adhesive layer has little adhesive residue and does not deviate from the mask. Elastic modulus of the pressure-sensitive adhesive layer is more preferably 30 mN / mm ² or more 150 mN / mm ² or less, further preferably 35 mN / mm ² or more 120 mN / mm ² or less.

In this embodiment, it is preferable that an adhesive layer contains a synthetic resin. By including the synthetic resin in the pressure-sensitive adhesive layer, the residual stress value α and the stress retention rate can be set in a suitable range.
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)
The (meth) acrylic ester elastomer preferably contains an acrylic base polymer (A) and a tackifier.
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.

The acrylic base polymer (A) allows the adhesive layer to be applied to the pellicle frame thickly, and from the viewpoint that the mask distortion when the pellicle is attached to the mask can be further reduced. A polymer is preferred.
As the block copolymer, the general formula (I):
-(A1)-(b)-(a2)-
Those consisting of are preferred.
The glass transition temperatures of (a1) and (a2) in general formula (I) are preferably 80 ° C. or higher. The glass transition temperature Tg of (b) in the general formula (I) is preferably 30 ° C. or lower. Moreover, it is preferable that (b) of general formula (I) is a block polymer which has in the main chain the polymer whose glass transition temperature Tg is 30 degrees C or less.

Monomer constituting the polymer block represented by (a1) and (a2) of the general formula (I) (hereinafter, the polymer block (a1) and the polymer block (a2) are collectively referred to as “polymer block a”). The component is preferably a methacrylic acid alkyl ester having 1 to 14 carbon atoms mainly from the viewpoint of setting the glass transition temperature of the polymer block a to 80 ° C. or higher. It is particularly preferable that the glass transition temperature of the polymer block a is 80 ° C. or higher, since a sufficient holding power and cohesive strength at high temperatures can be obtained.
“Mainly” means that at least more than half of the entire polymer block a, preferably 80% by mass or more, is occupied by an alkyl ester having 1 to 14 carbon atoms.
At least one of the polymer blocks a may be made of a methacrylic acid alkyl ester having 1 to 14 carbon atoms.

Examples of the alkyl ester having 1 to 14 carbon atoms in the polymer a include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec sec methacrylate. -Butyl, tert-butyl methacrylate, pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyl methacrylate Examples include decyl.
From the viewpoint of setting the glass transition temperature of the polymer block a to 80 ° C. or higher, an ester composed of methacrylic acid and an alcohol having 3 or less carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, etc. The main monomer component is preferred.
The alkyl ester having 1 to 14 carbon atoms may be used alone or in combination of two or more.

Monomer components other than methacrylic acid alkyl ester having 1 to 14 carbon atoms and less than half, preferably 20% or less, may be used for polymer block a.
Examples of the monomer component include methacrylic acid esters other than methacrylic acid alkyl esters such as trimethylsilyl methacrylate, trimethoxysilyl propyl methacrylate, glycidyl methacrylate, and allyl methacrylate; methyl acrylate, n-butyl acrylate, acrylic acid t -Acrylic acid alkyl ester such as butyl; Olefin such as ethylene and propylene; Lactone 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 formula (I) (hereinafter referred to as “polymer block b”) is mainly an alkyl acrylate ester and / or an alkyl methacrylate ester having 1 to 14 carbon atoms. From the viewpoint of setting the glass transition temperature of the polymer block b to 30 ° C. or lower. It is preferable that the glass transition temperature of the polymer block b is 30 ° C. or less, since sufficient adhesive strength and holding power can be obtained.
“Mainly” means that at least half of the entire polymer block b is occupied, and preferably 80% or more is occupied by an alkyl acrylate and / or methacrylic acid alkyl ester having 1 to 14 carbon atoms.

Examples of the alkyl ester having 1 to 14 carbon atoms in the polymer block b include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic acid Examples include sec-butyl, t-butyl acrylate, pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate.
When alkyl acrylate is used as the main monomer component, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. are mainly used from the viewpoint of setting the glass transition temperature of polymer block b to 30 ° C. or lower. It is preferable to use the monomer component.
As a C1-C14 methacrylic acid alkyl ester in the polymer block b, the same compound as the C1-C14 methacrylic acid alkyl ester in the polymer a 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. Monomer component mainly composed of esters of methacrylic acid and alcohols having 4 or more carbon atoms, such as n-hexyl acid, 2-ethylhexyl methacrylate, pentadecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyldecyl methacrylate It is preferable that
The C1-C14 acrylic acid alkyl ester and / or methacrylic acid alkyl ester may be used singly or in combination of two or more.

The polymer block b is less than half, preferably 20% or less, and has a C 1-14 alkyl ester and / or methacrylic acid alkyl ester within a range that does not adversely affect adhesive residue and light resistance on the mask. Other monomer components 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.

The block copolymer represented by the formula (I) has a structure in which one polymer block b is located between two polymer blocks a. If such a structure composed of three polymer blocks is included, not only a block copolymer composed of only these three polymer blocks but also one or more other polymer blocks are included. It may be a block copolymer composed of one or more polymer blocks.
The other polymer block may be the same type of polymer block as the polymer block a or the polymer block b, or may be a different type of polymer block c from the polymer block a or the polymer block b. Good. 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 the acrylic base polymer (A), (a1)-(b)-(a2), (a1)-(b)-(a2)-(b), (a1)-(b)-(a2)- Examples thereof include block copolymers such as (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 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, and 50,000 to 400. More preferably, it is in the range of 1,000.
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. . Further, the adhesive residue of the pressure-sensitive adhesive layer is improved, and the 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.

In the block copolymer, the ratio (a / b) of the total mass of the polymer block a based on the total mass of the polymer block b contained in the molecule is 5/95 to 80/20. Is preferable, and it is more preferable that it is 10 / 90-75 / 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.

You may form the side chain which has a bulky branched structure in a block copolymer. By forming a side chain with a bulky branched structure, the block copolymer can be applied thickly and mask distortion when the pellicle is attached to the mask can be further reduced. become.
Hydroxyl group, carboxyl group, acid anhydride group, amino group, etc. in the molecular side chain or at the molecular chain end so as not to adversely affect the adhesive residue on the mask and the light resistance as the acrylic base polymer (A) It may have a functional group of

  Specific examples of the acrylic base polymer (A) include a trade name “Clarity (registered trademark)” series (manufactured by Kuraray Co., Ltd.) and a trade name “Nanostrength” series (manufactured by Arkema Co., Ltd.).

(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”). It preferably contains a copolymer and a tackifier.
The block copolymer may be an unhydrogenated product or a hydrogenated product. Moreover, this block copolymer may be used by 1 type, or may use 2 or more types.

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.
“Mainly” means that the monomer units constituting the polymer block exceed half.
The aromatic vinyl compound unit may be used alone or in combination of two or more.

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. For example, 1,3-butadiene, 2-methyl-1,3- Examples thereof include structural units derived from conjugated diene compounds such as butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, structural units derived from 1,3-butadiene and isoprene are preferable.
“Mainly” means that the monomer units constituting the polymer block exceed half.
The conjugated diene unit may be used alone or in combination of two or more.

Although there is no restriction | limiting in particular in the mass fraction of the polymer block e, It is preferable that it is 60 mass% or more, and it is more preferable that it is less than 65 mass%.
When the mass fraction is 60% by mass or more, since there are many polymer blocks e having flexibility, 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), examples of the block copolymer include a triblock copolymer represented by (d)-(e)-(d) , (D)-(e)-(d)-(e) tetrablock copolymer, (d)-(e)-(d)-(e)-(d) Copolymer, ((d)-(e)) _n X-type polymer (X represents a coupling agent residue, and n represents an integer of 2 or more) and the like.
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 is preferably in the range of 10,000 to 500,000 and more preferably in the range of 30,000 to 350,000 in terms of weight average molecular weight.
If the weight average molecular weight of the block copolymer is within the above range, it is preferable from the viewpoint of obtaining good moldability and adjusting the residual stress value α and the stress retention to a preferable range.
The glass transition temperature (Tg) of the block copolymer is preferably from −60 ° C. to 40 ° C., more preferably from −50 ° C. to 35 ° C., and from −45 ° C. to 30 ° C. Is more preferable. 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” means that the block based on the conjugated diene is not hydrogenated.
Specific examples of the “unhydrogenated block copolymer” 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” 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 styrene-based elastomer, it is preferable to use a hydrogenated product of a block copolymer 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. For example, the product name “ASAPREN (registered trademark)” series, the product name “TUFTEC (registered trademark)” series, and the product name “TUFPRENE (registered trademark)” series ( Asahi Kasei Chemicals Corporation); trade name TR2003, trade name TR2500, and trade name TR2600 (manufactured by JSR Corporation); trade name Stereon 857 and trade name Stereon 841A (manufactured by Firestone); trade name Clayton D1118; Trade name Clayton (registered trademark) G1654 and trade name Clayton (registered trademark) G1726 (manufactured by Clayton Polymer Co., Ltd.); Trade name Sol T166 (manufactured by Enichem); Product name Septon TM) 2002, and the trade name Septon (registered trademark) 2063 (manufactured by Kuraray Co., Ltd.), and the like.

(Olefin elastomer)
The olefin-based elastomer preferably contains a copolymer of one or more α-olefins and a tackifier, and the copolymer is preferably amorphous or low crystalline. Moreover, this copolymer may be used by 1 type, or may use 2 or more types.
Examples of the α-olefin include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, 4-methylpentene-1, and the like.
Specific examples of the copolymer include a trade name “Tafmer (registered trademark)” series, a 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 order to control tackiness.
Examples of tackifiers include acrylic polymers, rosin and derivatives thereof, natural terpene copolymers, three-dimensional polymers of natural terpenes, hydrogenated terpene copolymers, polyterpene resins, 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, hydrogen of cyclic aliphatic petroleum hydrocarbon resins And the like.
As the tackifier, a liquid type tackifier can also be used as long as the color tone is colorless to light yellow and has substantially no odor and good thermal stability.
The tackifier may be used alone or in combination of two or more.

As a tackifier for the styrene elastomer, a hydrogenated derivative of a cycloaliphatic petroleum hydrocarbon resin is preferable in view of high compatibility with the styrene elastomer, and as the hydrogenated derivative, a hydrogenated dicyclopentadiene resin is used. Can be mentioned.
Commercially available products may be used as the tackifier, 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 (Yasuhara Chemical). Product name ECR5400, product name ECR179EX (manufactured by Exxon); product name Quinton (registered trademark) DX395, and product name Quinton (registered trademark) DX390N (manufactured by Nippon Zeon Co., Ltd.).

As a tackifier for (meth) acrylic ester elastomer, acrylic polymer and rosin and its derivatives are preferable in view of high compatibility with acrylic base polymer (A), in order to reduce mask distortion. Since it is necessary to be a soft adhesive, an acrylic polymer is more preferable.
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 distinguished from the acrylic base polymer (A) and is referred to as an acrylic polymer (B).
(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). It is considered that the use of the acrylic polymer (B) improves the 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. Further, the acrylic polymer (B) can exhibit flexibility as an adhesive layer by using the acrylic base polymer (A), reduce the residual stress value α, and increase the stress retention rate. become.

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 composed of 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.

Examples of the (meth) acrylic acid alkyl ester having 1 to 14 carbon atoms include (meth) acrylic acid esters of linear aliphatic alcohols, (meth) acrylic acid alkyl esters of branched aliphatic alcohols, etc. Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic Sec-butyl acid, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic Isooctyl acid, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, ( Data) hydroxypropyl acrylate, glycidyl (meth) acrylate, and 2-methoxyethyl acrylic acid.
Especially, since it is easy to have compatibility with the monomer component which can express the adhesiveness of acrylic base polymer (A), methyl (meth) acrylate, (meth) ethyl acrylate, (meth) acrylate n-butyl, (meta ) Isobutyl acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxy (meth) acrylate C1-C8 (meth) acrylic acid alkyl esters such as ethyl 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, even when the compound having a molecular weight of 800 or less is set to 18% by mass or less, the adhesive force of the pressure-sensitive adhesive layer can be expressed well and the adhesive residue can be improved.
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.

Specific examples of the acrylic polymer (B) 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.), and the like. .
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.

  Further, in order to impart adhesive strength, a random copolymer of (meth) acrylic acid ester copolymer can be blended.

  The (meth) acrylic acid ester elastomer, styrene elastomer and olefin elastomer may further contain a softening agent such as polybutene.

(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 wetness to the adherend, and is compatible with the block copolymer. There is no particular limitation as long as it can be obtained.
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. Specifically, the trade name White Oil Broom 350 (manufactured by Kukdong Oil & Chem), the trade name Diana Fresia (registered trademark) S32, and the trade name Diana Process Oil (registered trademark) PW. -90, trade name Diana Process Oil (registered trademark) NS-100, trade name DN Oil KP-68 (made by Idemitsu Kosan Co., Ltd.), trade name KN4010 (made by Petro China Company), trade name Energy M1930 (made by BP Chemicals) And trade name Kaydol (registered trademark) (manufactured by Crompton) and trade name Primol (registered trademark) 352 (manufactured by Esso).
Particularly in the case of a styrene-based elastomer, by adding a plasticizer, it can be made moderately soft, 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.
Examples of the antioxidant include phenolic antioxidants, and examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers and benzophenone-based 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 a styrene-based elastomer, deterioration due to heat or the like can be prevented by adding such an additive, which is preferable.

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

(Crosslinked acrylic resin)
A cross-linked pressure-sensitive adhesive may be used for the pressure-sensitive adhesive layer, and examples of the cross-linked 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 material as a crosslinkable acrylic resin, the crosslink density can be adjusted, and the residual stress value α can be 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 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. Also, the higher the crosslink density and Tg, the less the residual stress is relaxed, and the greater the stress retention.

The (meth) acrylic acid alkyl ester copolymer is a monomer having a functional group having reactivity with a C1-C14 (meth) acrylic acid alkyl ester (hereinafter referred to as “Component A”) and a curing material ( 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 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.

  The pressure-sensitive adhesive layer used in the pellicle of this embodiment is preferably composed of a resin composition containing a reaction product of a (meth) acrylic acid alkyl ester copolymer and a curing material, but in consideration of softness, The resin composition containing the reaction product which does not contain a hardening material may be sufficient.

The curing material 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 material 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.

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 a haze 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-morpholy ) 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 contain conventionally known additives such as fillers, pigments, diluents, anti-aging agents, and ultraviolet stabilizers 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 attach (apply) the pressure-sensitive adhesive layer 10 to the end surface of the pellicle frame 2 as a pressure-sensitive adhesive layer having a predetermined 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 pressure-sensitive adhesive composition may be applied to the other end surface 2 f of the pellicle frame 2 to form the pressure-sensitive adhesive layer 10, and then the pellicle film 3 may be attached to the one end surface 2 e of the pellicle frame 2 to form the pellicle 1.
Third, when the pressure-sensitive adhesive composition is diluted with a solvent, the pressure-sensitive adhesive layer 10 formed by heating and drying the applied pressure-sensitive adhesive composition is brought into close contact with the other end surface 2f of the pellicle frame 2. When the pressure-sensitive adhesive composition is applied by the hot melt method, the cooled pressure-sensitive adhesive composition is brought into close contact with the other end surface 2 f of the pellicle frame 2 after molding the applied pressure-sensitive adhesive composition. 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 may be applied. 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 pressure-sensitive adhesive surface of the pressure-sensitive adhesive 10 is pasted, the pressure-sensitive adhesive surface may be formed substantially flat by applying a weight.

Moreover, the pellicle of this embodiment can be suitably manufactured by the following method, for example.
First, a (meth) acrylic acid alkyl ester copolymer and a curing material or a curing material solution are mixed to obtain an adhesive precursor composition. In this case, in order to apply a mask pressure-sensitive adhesive layer having a predetermined 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 material are reacted by heating to form a cross-linked structure, the pellicle frame 2 and the pressure-sensitive adhesive composition are integrated, and the surface of the pellicle frame 2 is integrated. The spreader layer 10 adheres.
The drying temperature is preferably 50 to 200 ° C., 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.
After providing the adhesive layer 10 on the other end surface 2f of the pellicle frame 2, the pellicle film 3 may be attached to the one end surface 2e of the pellicle frame 2 to form the pellicle 1.

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 the aluminum material used as the pellicle frame has fine irregularities, and the adhesive layer, which is more flexible than the pellicle frame, absorbs the irregularities so that the mask surface is not affected by the irregularities on the surface of the aluminum material. Flatness can be obtained.
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.

  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.

The following were used for the base polymer, tackifier, and softener. In parentheses, the glass transition temperature measured based on the following (1) is shown.
(Base polymer)
・ (Meth) acrylate block copolymer Clarity (registered trademark) LA2140e (manufactured by Kuraray Co., Ltd.) (−38 ° C.)
・ (Meth) acrylate block copolymer Clarity (registered trademark) LA2330 (manufactured by Kuraray Co., Ltd.) (−39 ° C.)
・ Styrene-hydrogenated isoprene-styrene block copolymer Hibler 7125 (trade name) (manufactured by Kuraray Co., Ltd.)) (−15 ° C.)
(Tackifier)
・ ARUFON (registered trademark) UP1190 (manufactured by Toagosei Co., Ltd.) (−50 ° C.)
ARUFON (registered trademark) UP1080 (manufactured by Toagosei Co., Ltd.) (−61 ° C.)
ARUFON (registered trademark) UP1000 (manufactured by Toagosei Co., Ltd.) (−77 ° C.)
・ Clarity (registered trademark) LA1114 (manufactured by Kuraray Co., Ltd.) (−40 ° C.)
Pine Crystal (registered trademark) KE-311 (Arakawa Chemical Industries, Ltd.) (softening point 100 ± 5 ° C.)
Alcon (registered trademark) P100 (Arakawa Chemical Industries, Ltd.) (softening point 100 ± 5 ° C.)
I-BA / BA / AA / HEA (isobutyl acrylate / butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate) (−51 ° C.)
(Softener)
・ Nissan Polybutene 30N (manufactured by NOF Corporation)
ARUFON (registered trademark) UP1080 (manufactured by Toagosei Co., Ltd.) (−61 ° C.)

The glass transition temperature of the resin used for the base polymer and tackifier was measured based on the glass transition temperature measured by DSC (differential scanning calorimetry).
・ Device: DSCQ2000 manufactured by TA Instruments
・ Seal pan ・ Temperature range: -80 ℃ ～ 160 ℃
・ Raising rate: 5 ° C / min
・ Sample weight: 10mg
When the glass transition temperature was plural for the base polymer and the tackifier, the temperature on the low temperature side was described as a value.

Each measurement method and evaluation method in the present embodiment are as follows.
(1) Measurement of residual stress after relaxation of 20% elongation / 24 hours Cut one side of the pellicle with protective film, and then slowly peel off the protective film so that the adhesive layer does not deform, and then remove it from the pellicle frame The mask adhesive layer was slowly peeled off. At that time, when it was difficult to peel off, the sticker roll was slowly peeled off while adhering to the hand and the pressure-sensitive adhesive layer so that the elongation rate of the peeled pressure-sensitive adhesive layer was 5% or less.
The peeled adhesive layer 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
The above apparatus was pulled to an elongation of 20%, the crosshead was stopped and relaxed, and the change with time of stress up to 24 hours later was measured.
Separately, the cross-sectional area of the pressure-sensitive adhesive layer was measured, and the measurement result was divided by the cross-sectional area to obtain a residual stress value α when relaxed for 24 hours per unit area. Further, the stress retention rate was determined from the maximum stress value α _max at 20% elongation and the residual stress value α when relaxed for 24 hours after 20% elongation.
In addition, the cross-sectional area cut | disconnects the other one side of the said pellicle with a protective film, and peels a protective film slowly so that an adhesive layer may not deform | transform after that. Cut to a length of about 1 cm, embedded in resin, and let the resin cure naturally. 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.

(2) Measurement of elastic modulus Cut one side of the pellicle with protective film, then slowly peel off the protective film so that the adhesive layer does not deform, and then slowly peel off the mask adhesive layer 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 of the peeled pressure-sensitive adhesive layer was adjusted to 5% or less.
The peeled adhesive layer was measured at room temperature (25 ° C.) using the following apparatus.
Device name: Autograph (SHIMAZU EZ-S manufactured by Shimadzu Corporation)
Load cell: 1N (clip type chuck)
Between chucks: 40mm
Cross head speed: 100 mm / min.
With the above apparatus, the pressure-sensitive adhesive layer was pulled to an elongation of 20%. Separately, the cross-sectional area of the pressure-sensitive adhesive layer was measured, and the measurement result was divided by the cross-sectional area to obtain the stress value per unit area.
Create a graph consisting of the elongation on the x-axis and the stress value per unit area on the y-axis, and the y-axis value at 100% elongation when a straight line is drawn at 0% elongation and 20% elongation. Elastic modulus was used.

(3) 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: 15 Kgf, 60 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.
◎: Deformation of mask due to pasting pellicle is 25 nm or less ○: Deformation of mask due to pasting pellicle is over 25 nm to 35 nm or less Δ: Deformation of mask due to pasting pellicle is over 35 nm 50 nm or less x: Deformation amount of the mask by attaching a pellicle exceeds 50 nm

(4) Evaluation of pellicle displacement The pellicle was affixed to a mask (6025 quartz) using a simple mounter (weight: 15 Kgf, 60 sec), placed vertically in a mask case, and stored in a clean room for 10 days. Ten days later, the displacement of the pellicle from the mask was visually evaluated.
○: No deviation from mask ×: There is deviation from mask

<Example 1>
(Production of pellicle)
70 parts by mass of “Clarity LA1114” as a tackifier and 30 parts by mass of “Clarity LA2140e” as a base polymer were mixed so as to give a total of 48 g to obtain a raw material mixture. 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. Here, as a pin hole, there are 4 jig holes each having a hole diameter of 1.6 mmφ and a depth of 1.2 mm at a position of 1.7 mm from the film adhesive application end surface and at a position of 25 mm from the corner portion of the outer side surface of the pellicle frame. We established several places. The molten pressure-sensitive adhesive composition extruded from the needle tip communicating with the heating tank was applied onto one end surface of the pellicle frame to form a pressure-sensitive adhesive layer. The thickness of the formed adhesive layer was 0.6 mm. Thereafter, a 100 μm-thick polyester protective film subjected to silicone release treatment was bonded to the surface of the pressure-sensitive adhesive layer. A pellicle film was attached to the other end surface of the pellicle frame via a film adhesive layer to produce a pellicle.
The obtained pellicle was subjected to mask distortion evaluation and pellicle displacement evaluation. The results are shown in Table 1.

<Examples 2 to 8>
A pellicle was produced in the same manner as in Example 1 except that the components were mixed to obtain a mixture as shown in Table 1 to obtain a mixture.
Evaluation similar to Example 1 was implemented with respect to the obtained pellicle. The results are shown in Table 1.

<Comparative 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). 0.025 parts by mass of a polyfunctional epoxy compound (a toluene solution of 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, non-volatile content 5%) to 100 parts by mass of the obtained acrylic copolymer solution Addition and stirring were mixed to obtain an adhesive precursor composition.
An anodized aluminum alloy pellicle frame (outer diameter 113 mm × 149 mm, inner diameter 109 mm × 145 mm, height 3.2 mm) was prepared. The obtained pressure-sensitive adhesive precursor composition was applied onto one end surface of the pellicle frame with a dispenser. This was heat-dried and cured in two stages (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 subjected to silicone release treatment was bonded to the surface of the pressure-sensitive adhesive layer, and cured for 3 days at room temperature (20 ± 3 ° C.) to stabilize the adhesive force. The thickness of the formed pressure-sensitive adhesive layer was 0.3 mm. A pellicle film was attached to the other end surface of the pellicle frame via a film adhesive layer to produce a pellicle.
Evaluation similar to Example 1 was implemented about the obtained pellicle. The results are shown in Table 1.

<Comparative example 2>
Melting and mixing 100 parts by mass of styrene ethylene butylene styrene copolymer, 80 parts by mass of hydrogenated terpene resin, 40 parts by mass of paraffinic process oil and 2 parts by mass of antioxidant (BHT) at 220 ° C. using a kneader. As a result, a massive mask adhesive was obtained. About 10 g of the mask adhesive 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. A molten mask adhesive extruded from the needle tip communicating with the heating tank was applied onto one end surface of the pellicle frame to form an adhesive layer. The thickness of the formed pressure-sensitive adhesive layer was 0.6 mm. Thereafter, a 100 μm-thick polyester protective film subjected to silicone release treatment was bonded to the surface of the pressure-sensitive adhesive layer. A pellicle film was attached to the other end surface of the pellicle frame via a film adhesive layer to produce a pellicle.
The obtained pellicle was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Examples 3-6>
A pellicle was produced in the same manner as in Example 1 except that the components were mixed to obtain a mixture as shown in Table 1 to obtain a mixture.
Evaluation similar to Example 1 was implemented with respect to the obtained pellicle. The results are shown in Table 1.

  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). Further, 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 (4)

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 pressure-sensitive adhesive layer is a pellicle having a residual stress value after relaxation of 20% elongation / 24 hours of 1.0 mN / mm ^{2 to} 12.0 mN / mm ² .   The pellicle according to claim 1, wherein the adhesive layer has a stress retention of 42% or more. The elastic modulus of the adhesive layer is 20 mN / mm ² or more 180mN / mm ² or less, pellicle according to claim 1 or 2.   The pellicle according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer contains an acrylic resin or a synthetic rubber resin.