JP2022107295A - Pellicle - Google Patents

Abstract

To provide a pellicle whereby it is possible to prevent an adhesive from remaining when removing the pellicle from a mask and also to suppress a warp in the mask to a smaller level.SOLUTION: A pellicle has a frame, a pellicle film disposed on one side of the frame, and an adhesive layer disposed on the other side of the frame. The adhesive layer contains a crosslinked acrylic copolymer, which contains (A) a copolymer containing a methacrylate monomer and a monomer having a specific functional group and (B) a curing agent reactable with the monomer having a specific functional group. The (A) copolymer has a glass transition temperature of -53°C to -40°C as determined by Fox Equation.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pellicle.

In the manufacturing process of large-scale integrated circuits (LSIs) and the like, pellicle is used to prevent dust from the photomask. The pellicle is generally arranged on the frame (pellicle frame), the pellicle film which is a transparent thin film arranged on one side of the frame, and the other side of the frame (the side opposite to the pellicle film of the pellicle frame). It has an adhesive layer for being attached to a photomask.

When the pellicle is peeled off from the mask, there is a problem that the adhesive remains on the mask side, that is, so-called adhesive residue. The adhesive easily reacts with the surface of the mask when exposed to stray light during exposure, which is considered to be one of the causes of adhesive residue. For example, when the mask is made of quartz glass, since the hydroxyl group exists on the surface of the mask, a bond occurs between the hydroxyl group and the carboxylic acid group contained in the pressure-sensitive adhesive, and the mask becomes stronger with time.

Conventionally, a chrome-deposited film has been formed at a place where a pellicle is attached in a photomask. That is, since the place where the pellicle is attached is shielded from light by chrome, the light does not directly hit it, and the adhesive residue is suppressed by suppressing the increase in the adhesive force between the adhesive and chrome over time.

However, in recent years, the chromium-deposited film may be omitted in the place where the pellicle is attached. If the pellicle is directly attached to the photomask without passing through the chrome-deposited film, the adhesive of the pellicle is easily exposed to light, and adhesive residue is likely to occur.

So far, studies have been conducted on pellicle that reduces the adhesive residue on the mask when the pellicle is peeled off from the mask. For example, Patent Document 1 discloses a pellicle in which the total functional group concentration of a hydroxyl group, a carboxyl group, and an epoxy group is 0.008 mmol / g or less in a non-crosslinked acrylic pressure-sensitive adhesive. Further, Patent Document 2 discloses a pellicle in which the content of the carboxylic acid-containing monomer unit in the pressure-sensitive adhesive is 0.9% by mass or less with respect to 100% by mass of the (meth) acrylic acid alkyl ester copolymer. There is.
In these documents, the generation of adhesive residue is prevented by suppressing the reaction between the adhesive and the mask surface by limiting the functional group concentration.

Japanese Unexamined Patent Publication No. 2015-114502 Japanese Unexamined Patent Publication No. 2016-156882

Further, as the pattern becomes higher definition, the distortion of the mask has come to be regarded as a problem. The pellicle attached to the mask is also one of the causes of mask distortion, and it is said that the distortion of the frame of the pellicle causes the distortion of the mask.

However, it has been difficult to both prevent adhesive residue during pellicle peeling and suppress distortion of the mask.

The present invention has been proposed in view of such conventional circumstances, and an object of the present invention is to prevent adhesive residue when peeling a pellicle from a mask and to suppress distortion of the mask to be smaller. It is to provide a pellicle that can be used.

[1]
A pellicle having a frame, a pellicle film arranged on one surface side of the frame, and an adhesive layer arranged on the other surface side of the frame.
The pressure-sensitive adhesive layer comprises (A) a copolymer containing a (meth) acrylic acid ester monomer and a monomer having a specific functional group, and (B) a curing agent that reacts with the monomer having a specific functional group. Contains a crosslinked acrylic copolymer containing,
The following formula (1):
Fox formula: 1 / Tg = Σ (Wn / Tgn) (1)
{In the formula, Tg (K) is the glass transition temperature of the copolymer (A), Wn (-) is the mass fraction of each monomer, Tgn (K) is the glass transition temperature of the homopolymer by each monomer, and n is. Represents the type of each monomer. }
The pellicle obtained by the above (A), wherein the glass transition temperature of the copolymer (A) is −53 ° C. to −40 ° C.
[2]
The pellicle according to [1], wherein the 20% elongation stress of the pressure-sensitive adhesive layer is 15 mN / mm ² to 45 mN / mm ² .
[3]
The pellicle according to [1] or [2], wherein the residual stress of the pressure-sensitive adhesive layer is more than 0 to 10 mN / mm ² .
[4]
The pellicle according to any one of [1] to [3], wherein the content of the carboxylic acid-containing monomer is 0.9% by mass or less with respect to 100% by mass of the copolymer (A).
[5]
The pellicle according to any one of [1] to [4], wherein the proportion of the copolymer (A) in 100% by mass of the pressure-sensitive adhesive layer is 98% by mass to 99.9% by mass.
[6]
The pellicle according to any one of [1] to [5], wherein the curing agent contains a polyfunctional isocyanate compound.

According to the present invention, it is possible to provide a pellicle that can prevent adhesive residue when peeling the pellicle from the mask and can suppress the distortion of the mask to be smaller.

It is a figure which shows one Embodiment of the pellicle of this invention.

Hereinafter, embodiments for carrying out the present invention (hereinafter, abbreviated as “embodiments”) will be described with reference to the drawings. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

<Pellicle>
1A and 1B are views showing one embodiment of the pellicle of the present invention, FIG. 1A is a top view, and FIG. 1B is a vertical sectional view.
In the following description, the upper side in each figure will be referred to as “upper” and the lower side will be referred to as “lower”.

The pellicle 1 is a structure that protects the photomask from dust in photolithography and the like. The pellicle 1 has a frame 2, a pellicle film 3 arranged on the one side 2a side of the frame 2, and an adhesive layer 4 arranged on the other side 2b side of the frame 2.
The pressure-sensitive adhesive layer 4 includes a copolymer containing (A) (meth) acrylic acid ester monomer and a monomer having a specific functional group (hereinafter, may be referred to as “acrylic copolymer”), and (B). It contains a crosslinked acrylic copolymer containing a curing agent that reacts with a monomer having a specific functional group.

Then, the pellicle 1 of the present invention has the following formula (1):
Fox formula: 1 / Tg = Σ (Wn / Tgn) (1)
{In the formula, Tg (K) is the glass transition temperature of the (A) copolymer, Wn (-) is the mass fraction of each monomer, Tgn (K) is the glass transition temperature of the homopolymer by each monomer, and n is each. Represents the type of monomer. }
The glass transition temperature of the (A) copolymer determined by the above is −53 ° C. to −40 ° C.

As a result, the pellicle 1 of the present invention can prevent adhesive residue when the pellicle 1 is peeled from the photomask, and can suppress the distortion of the photomask to a smaller size.

In the present specification, the photomask is assumed to be a photomask made of quartz glass and not provided with a chromium-deposited film.

The frame 2 (pellicle frame) can have an arbitrary form such that the pellicle film 3 can be stretched on the frame 2. For example, when the frame is viewed from the front, it has a square shape, a polygonal shape, a circular shape, an elliptical shape, or the like. Can have the outer shape of. The square is a square, a rectangle, or the like, and can have both a case where the corners are right angles and a case where the corners are rounded (FIG. 1). The polygon is a triangle, a trapezoid, a parallelogram, a pentagon, a hexagon, or the like.

The size of the frame 2 and its opening can be determined according to the size of the photomask. When the frame 2 has a rectangular shape consisting of a pair of long sides and a pair of short sides in a front view, the long side length is 80 mm to 300 mm, the short side length is 50 mm to 250 mm, and the long side and the short side. The widths of the sides can be 1.0 mm to 3.0 mm, respectively, and / or the height of the frame can be 1.5 mm to 6.0 mm.

As shown in FIG. 1, the frame 2 has an edge. The edge portion can have a rod-shaped edge member extending linearly. The pair of edge members can be arranged in parallel with a gap from each other, and similarly, the other pair of edge members can be arranged in parallel with a distance from each other. The ends of the two contacting edge members can be connected so that they form a substantially right angle to each other.

The frame 2 and its edge members are, for example, aluminum; aluminum alloy (for example, 5000 series, 6000 series, 7000 series, etc.); steel; stainless steel; magnesium alloy; ceramics (for example, SiC, AlN, Al ₂ O ₃ , etc.); ceramics. Composite materials of and metal (eg, Al-SiC, Al-AlN, Al-Al ₂ O ₃ etc.); engineering plastics such as PE, PA, PC, PEEK; fiber composite materials such as GFRP, CFRP; or these It can be made of known materials such as combinations.

If necessary, an adhesive (for example, acrylic, vinyl acetate, silicone, rubber adhesive, etc.) or grease (for example, silicone) for capturing foreign matter or grease (for example, silicone) is applied to the inner peripheral surface or the entire surface of the frame 2. System, fluorine-based grease, etc.) may be applied.

The pellicle film 3 is a transparent thin film formed of a fluoropolymer. The pellicle film 3 has a thickness of 1 μm or less, and is formed so as to sufficiently transmit the light emitted by the light source in photolithography. As shown in FIG. 1B, the pellicle film 3 is adhered and fixed to one side of the frame 2 with an adhesive (not shown) to cover the frame 2.

As shown in FIG. 1B, an adhesive layer 4 for attaching the pellicle 1 to the photomask is arranged on the other surface 2b side of the frame 2 (the side opposite to the pellicle film 3 of the frame 2). There is.

The pressure-sensitive adhesive layer 4 is crosslinked containing (A) a copolymer containing a (meth) acrylic acid ester monomer and a monomer having a specific functional group, and (B) a curing agent that reacts with the monomer having a specific functional group. Contains a type acrylic copolymer.

(A) Copolymer (acrylic copolymer)
Examples of the (meth) acrylic acid ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, octyl methacrylate and nonyl acrylate. , Nonyl methacrylate, dodecyl acrylate, (meth) acrylic acid alkyl ester such as dodecyl methacrylate and the like. These alkyl portions may be linear or branched chain. Further, these (meth) acrylic acid ester monomers may be used individually by 1 type, or may be used in combination of 2 or more type.

As the monomer having a specific functional group, a vinyl-based monomer having a specific functional group is preferable. The "specific functional group" referred to here is preferably a functional group having reactivity with a curing agent described later, and is, for example, a carboxyl group and / or a hydroxyl group. Examples of the vinyl-based monomer having a specific functional group include vinyl-based monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and maleic acid; 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl. Examples thereof include vinyl-based monomers having a hydroxyl group such as (meth) acrylate and 2-hydroxyhexyl (meth) acrylate.

(B) Curing Agent The curing agent that reacts with the monomer having a specific functional group preferably contains a polyfunctional isocyanate compound from the viewpoint of reactivity with the specific functional group. Examples thereof include trimethylolpropane tolylene diisocyanate-based and methylene diisocyanate-based polyfunctional isocyanate compounds.

Then, the pellicle 1 of the present invention has the following formula (1):
Fox formula: 1 / Tg = Σ (Wn / Tgn) (1)
{In the formula, Tg (K) is the glass transition temperature of the (A) copolymer, Wn (-) is the mass fraction of each monomer, Tgn (K) is the glass transition temperature of the homopolymer by each monomer, and n is each. Represents the type of monomer. }
The glass transition temperature of the (A) copolymer determined by the above is −53 ° C. to −40 ° C.
If the glass transition temperature is too low, the peeling force from the photomask becomes large, and there is a possibility that adhesive remains when the pellicle 1 is peeled. If the glass transition temperature is too high, the adhesive force with the glass is extremely reduced, and the pellicle 1 may be peeled off from the glass. When the glass transition temperature is in the above range, the adhesive force with the glass is lowered, and the adhesive residue can be reduced when the pellicle 1 is peeled off.
The glass transition temperature of the (A) copolymer is preferably −53 ° C. to −40 ° C., more preferably −52 ° C. to −42 ° C.

Further, in the pellicle 1 of the present embodiment, the peeling force of the pressure-sensitive adhesive layer 4 with respect to the photomask is preferably 5 kgf to 15 kgf, more preferably 6 kgf to 13 kgf, and further preferably 7 kgf to 12 kgf.
If the peeling force is too small, the adhesiveness may not be sufficient and the fixing to the photomask may be insufficient. On the other hand, if the peeling force is too large, there is a possibility that adhesive remains when the pellicle 1 is peeled from the photomask. When the peeling force is within the above range, it can be sufficiently fixed to the photomask and the adhesive residue at the time of peeling can be prevented.

The 20% elongation stress of the pressure-sensitive adhesive layer 4 is preferably 15 mN / mm ² to 45 mN / mm ² .
If the 20% elongation stress is too low, the pressure-sensitive adhesive layer 4 is likely to coagulate and break, and there is a possibility that adhesive remains. On the other hand, if the 20% elongation stress is too large, the adhesive force with the glass after being attached to the photomask becomes too strong, and there is a possibility that adhesive remains. Furthermore, the ability to reduce the distortion of the mask is reduced, and the distortion of the photomask may be increased. When the 20% elongation stress is in the above range, the cohesive force of the pressure-sensitive adhesive is high and it is difficult for adhesive to remain. The 20% elongation stress is more preferably 18 mN / mm ² to 38 mN / mm ² .

The residual stress of the pressure-sensitive adhesive layer 4 is preferably more than 0 to 10 mN / mm ² , more preferably more than 0 to 8 mN / mm ² , and even more preferably more than 0 to 6 mN / mm ² . The lower the residual stress value, the smaller the distortion of the photomask can be suppressed.

The content of the carboxylic acid-containing monomer with respect to 100% by mass of the (A) copolymer is preferably 0.9% by mass or less, and more preferably 0.5% by mass or less.
By setting the content of the carboxylic acid-containing monomer within the above range, when the photomask is made of quartz glass, the reaction between the hydroxyl group existing on the photomask surface and the carboxylic acid-containing monomer can be suppressed to a small extent, and the photomask and the pressure-sensitive adhesive can be used. Can be prevented from being firmly bonded over time.

The proportion of the (A) copolymer in 100% by mass of the pressure-sensitive adhesive layer 4 is preferably 98.0% by mass to 99.9% by mass, preferably 99.0% by mass to 99.8% by mass. Is more preferable.
When the proportion of the copolymer (A) is in the above range, appropriate adhesiveness and peelability can be exhibited.

The pressure-sensitive adhesive layer 4 may further contain conventionally known additives such as fillers, pigments, diluents, anti-aging agents, and UV stabilizers, if necessary. It is possible to use one kind or two or more kinds of these additives. However, it is preferable to appropriately set the addition amount so that the desired physical properties can be obtained.

The thickness of the pressure-sensitive adhesive layer 4 is preferably 0.1 mm or more and 3.0 mm or less. For semiconductors, 0.1 mm or more and 1.0 mm or less is preferable, 0.12 mm or more and 0.8 mm or less is more preferable, and 0.14 mm or more and 0.5 mm or less is further preferable. For liquid crystals, 0.8 mm or more and 3.0 mm or less is preferable, 1.0 mm or more and 2.5 mm or less is more preferable, and 1.2 mm or more and 2.0 mm or less is further preferable.

The surface of the aluminum material generally used as the frame 2 may have fine irregularities, and the adhesive layer 4 which is more flexible than the frame 2 absorbs the irregularities on the surface of the aluminum material. It is possible to obtain the flatness of the photomask without being affected by the unevenness.
If the thickness of the pressure-sensitive adhesive layer 4 is within the above range, the unevenness of the surface of the frame 2 can be absorbed, the outgas from the pressure-sensitive adhesive layer 4 becomes a problem-free level while ensuring the flatness of the photomask, and the photomask can be used. It can be a pellicle with reduced mask distortion when crimped.

(Manufacturing method of pellicle)
The pellicle of the present embodiment can be suitably produced by, for example, the following method.
First, the (meth) acrylic acid alkyl ester copolymer is mixed with a curing agent or a curing agent solution to obtain a pressure-sensitive adhesive precursor composition. In this case, in order to apply the pressure-sensitive adhesive layer 4 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, but are not limited to, acetone, ethyl acetate, toluene and the like.

Second, the pressure-sensitive adhesive precursor composition is applied to the other surface 2b of the frame 2 having the pellicle film 3 stretched on one surface 2a. The coating method is not particularly limited, but it is preferable to apply using a dispenser. The viscosity of the acrylic copolymer solution (meaning a solution composed of a solvent and a (meth) acrylic acid alkyl ester copolymer) in the pressure-sensitive adhesive precursor composition is not particularly limited, but is preferably 50 P or less. It is more preferably 10 to 40 P, still more preferably 20 to 30 P (B-type viscometer, 25 ° C.).
By diluting with a solvent in coating with a dispenser, the coating liquid has less stringiness, and it becomes easy to adjust to a stable width and thickness.

Third, the solvent and / or residual monomer can be removed by heating and drying the applied pressure-sensitive adhesive layer 4. Further, when the functional group of the (meth) acrylic acid alkyl ester copolymer and the curing agent react with each other by heating to form a crosslinked structure, the frame 2 and the pressure-sensitive adhesive composition are integrated, and the pressure-sensitive adhesive is applied to the surface of the frame 2. The layers 4 are in close contact.
The drying temperature is preferably 50 to 200 ° C., more preferably 60 to 190 ° C. in consideration of the boiling points of the solvent and the residual monomer and the decomposition temperature of the (meth) acrylic acid alkyl ester copolymer. ..
After drying and cross-linking, a protective film 5 (release sheet) for protecting the adhesive surface may be attached.
The pellicle film 3 may be attached (stretched) to the frame 2 before or after the formation of the pressure-sensitive adhesive layer 4, and after the pressure-sensitive adhesive layer 4 is provided on the other surface 2b of the frame 2, the frame 2 is attached. The pellicle film 3 may be attached to one side 2a.

The pellicle 1 of the present embodiment may include a protective film 5 that protects the pressure-sensitive adhesive layer 4.
As the protective film 5 used in the present embodiment, a film having a thickness of about 30 to 200 μm, such as polyester, is generally used. Further, if the peeling force when peeling the protective film 5 from the pressure-sensitive adhesive layer 4 is large, the pressure-sensitive adhesive layer 4 may be deformed when peeled off. The film surface may be subjected to a mold release treatment such as silicone or fluorine. After the protective film 5 for protecting the adhesive surface is attached, a load may be applied to mold the surface of the adhesive layer 4 substantially flat.

Next, the present embodiment will be described more specifically with reference to Examples and Comparative Examples. However, the present embodiment is not limited to the following examples as long as it does not deviate from the gist thereof.

(Preparation of adhesive composition)
<Example 1>
The (meth) acrylic acid alkyl ester copolymer was prepared by the following method.
Specifically, ethyl acetate (30 parts by weight) is placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, and butyl acrylate (BA) / methyl methacrylate (MMA) / 2 is placed. A mixture of -hydroxyethyl acrylate (HEA) / 2, 2'-azobisisobutyronitrile (32 parts by weight) was charged at a weight ratio of 96/3/1 / 0.5, and this reaction solution was prepared in a nitrogen atmosphere. Was reacted at reflux temperature for 8 hours. After completion of the reaction, toluene (38 parts by weight) was added to obtain an acrylic copolymer solution having a non-volatile content concentration of 32% by weight. 0.9 part by weight of a polyfunctional isocyanate compound (trimethylolpropane tolylene diisocyanate) was added to 100 parts by weight of the obtained acrylic copolymer solution and mixed with stirring to obtain a pressure-sensitive adhesive composition.

<Examples 2 to 5, Comparative Examples 1 and 2>
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the mixing ratio of butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) was changed as shown in Table 1. rice field.

(Making a pellicle)
<Examples 1 to 5, Comparative Examples 1 and 2>
On the other side of the aluminum alloy pellicle frame (outer diameter 113 mm x 149 mm, inner diameter 109 mm x 145 mm, height 3.0 mm) with a pellicle film bonded to one side, the adhesive composition prepared as described above is dispensed with a dispenser. It was applied. This is heat-dried and cured in two steps (1st step: 100 ° C., 8 minutes; 2nd step: 180 ° C., 8 minutes) to form a pressure-sensitive adhesive layer (thickness 0.2 mm) containing the pressure-sensitive adhesive composition. Got

The obtained pellicle was evaluated by the following method.

(Glass transition temperature derived by Fox's equation)
The Tg (K: absolute temperature) of the polymer and the copolymer is determined from the copolymerization ratio (mass fraction in the copolymer) of the Tg of the homopolymer and the monomer of the monomer constituting the polymer. It was calculated according to Fox's equation (1).
Fox formula: 1 / Tg = Σ (Wn / Tgn) (1)
That is,
1 / Tg = W1 / Tg1 + W2 / Tg2 + ...
Tg: Tg (K) of a copolymer containing a structural unit derived from monomers 1, 2, ...
W1, W2 ...: Mass fraction of monomer 1, monomer 2, ... in the copolymer where W1 + W2 + ... = 1
Tg1, Tg2 ...: Monomer 1, monomer 2, ..., homopolymer Tg (K)

The Tg / ° C. values of the homopolymers of each monomer used to calculate the glass transition temperature (Tg / ° C.) of the copolymer by the Fox formula are shown below.
Butyl acrylate (BA): -55
Methyl methacrylate (MMA): 105
2-Hydroxyethyl acrylate (HEA): -15

In addition, 2,2'-azobisisobutyronitrile, Si-containing compound, has a radically polymerizable double bond such as a vinyl group, an acryloyl group or a methacryloyl group in the molecule, and is copolymerized with an acrylic monomer. Possible surfactants are not considered in the formula for calculating Tg above.

From the acrylic resin, the composition of the monomer unit can be analyzed by pyrolysis gas chromatography or mass analysis pyrolysis gas chromatography, and the Tg of the acrylic resin can be calculated from the above formula.

(Drivation of 20% elongation stress)
One side of the pellicle with the protective film was cut, and then the protective film was slowly peeled off so that the pressure-sensitive adhesive 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 siccarol 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 device.
Device name: Autograph (SHIMAZU EZ-S manufactured by Shimadzu Corporation)
Load cell: 1N (clip type chuck)
Between chucks: 10 mm
Crosshead speed: 5mm / min
With the above device, the stress value was measured by pulling up to an elongation of 20%.

(Derivation of residual stress)
By the same method as described above (derivation of 20% elongation stress), the crosshead was stopped and relaxed in a state where the pressure-sensitive adhesive layer was pulled to an elongation of 20%, and the change over time of the stress was measured up to 3 minutes later.
rice field.

(Evaluation of adhesive residue)
Regarding the pellicle obtained in each example, for the pellicle with a protective film, after peeling off the protective film, a weight (5 kgf, 60 sec) was attached to a photomask (6025 quartz) with a simple mounter, and the pellicle was attached. I got the wood.
The base material to which the pellicle was attached was irradiated with ultraviolet rays (DUV), and the pellicle was peeled off by pulling it up perpendicularly to the mask surface at a speed of 5 mm / min by a tensile tester. The adhesive residue was evaluated by observing the state of the surface of each adherend and using the following criteria.
◯: The remaining glue area is 0 to 5% of the total pasting area.
Δ: The adhesive remaining area is more than 5% to 20% of the total pasting area.
X: The adhesive remaining area is more than 20% to 100% of the total pasting area.
Irradiation of ultraviolet rays was performed with a Deep UV lamp at an illuminance of 15 mW / cm ² and 100 J / cm ² irradiation.

(Evaluation of photomask distortion)
The evaluation of the distortion (deformation) of the photomask was measured using FlatMaster 200 manufactured by Tropel. For the photomask (6025 quartz), the flatness before attaching the pellicle was measured, then the pellicle was attached, and the flatness 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 photomask was deformed by pasting the pellicle was calculated and evaluated according to the following criteria.
The pellicle was attached to the photomask with a simple mounter (weight: 5 kgf, 60 sec).
◯: Deformation amount of the photomask due to pasting the pellicle is less than 50 nm ×: Deformation amount of the photomask due to pasting the pellicle is 50 nm or more The evaluation results are shown in Table 1.

As is clear from Table 1, the pellicle of the comparative example did not sufficiently suppress the adhesive residue or the distortion of the photomask, whereas the pellicle of the example preferably suppressed the adhesive residue and the distortion of the photomask. Was there.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the spirit of the invention.

By using the pellicle according to the present invention, it is possible to suppress adhesive residue and distortion of the photomask, and it can be widely used as a pellicle for a photomask.

1: Pellicle 2: Frame 2a: One side 2b: Other side 3: Pellicle film 4: Adhesive layer 5: Protective film

Claims (6)

A pellicle having a frame, a pellicle film arranged on one surface side of the frame, and an adhesive layer arranged on the other surface side of the frame.
The pressure-sensitive adhesive layer comprises (A) a copolymer containing a (meth) acrylic acid ester monomer and a monomer having a specific functional group, and (B) a curing agent that reacts with the monomer having a specific functional group. Contains a crosslinked acrylic copolymer containing,
The following formula (1):
Fox formula: 1 / Tg = Σ (Wn / Tgn) (1)
{In the formula, Tg (K) is the glass transition temperature of the copolymer (A), Wn (-) is the mass fraction of each monomer, Tgn (K) is the glass transition temperature of the homopolymer by each monomer, and n is. Represents the type of each monomer. }
The pellicle obtained by the above (A), wherein the glass transition temperature of the copolymer (A) is −53 ° C. to −40 ° C. The pellicle according to claim 1, wherein the 20% elongation stress of the pressure-sensitive adhesive layer is 15 mN / mm ² to 45 mN / mm ² . The pellicle according to claim 1 or 2, wherein the residual stress of the pressure-sensitive adhesive layer is more than 0 to 10 mN / mm ² . The pellicle according to any one of claims 1 to 3, wherein the content of the carboxylic acid-containing monomer is 0.9% by mass or less with respect to 100% by mass of the copolymer (A). The pellicle according to any one of claims 1 to 4, wherein the proportion of the copolymer (A) in 100% by mass of the pressure-sensitive adhesive layer is 98% by mass to 99.9% by mass. The pellicle according to any one of claims 1 to 5, wherein the curing agent contains a polyfunctional isocyanate compound.

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