JP3091449B1 - UV resistant pellicle - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a saturated hydrocarbon-based pressure-sensitive adhesive layer on one end surface of a pellicle frame, thereby preventing fogging, gas generation, dust generation, adhesion strength reduction, etc. in the pellicle film due to light deterioration of the pressure-sensitive adhesive layer. Provide UV-resistant pellicle. SOLUTION: An ultraviolet-resistant pellicle characterized in that a hydrocarbon compound pressure-sensitive adhesive layer defined by the following formula (1) has a saturation degree S of 0.9 or more. S = H / (H + L) (1) (H; total of integrated values of peaks observed in a region where the value of chemical shift is 0.1 ppm or more and less than 4 ppm in proton NMR measurement of the pressure-sensitive adhesive layer, L; similarly, 4 ppm Above 1
Sum of integrated values of peaks observed at less than 0 ppm)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-proof cover for protecting a photomask, a reticle, and the like (hereinafter, referred to as a mask) used in a photolithography process in the manufacture of an LSI (Large Scale Integrated Circuit), that is, a pellicle. Things. More specifically, the present invention provides a pellicle film on one end surface of a pellicle frame, and an ultraviolet light resistant adhesive layer mainly composed of a hydrocarbon compound having a low unsaturated bond content formed on the other end surface. Sexual pellicle.

[0002]

2. Description of the Related Art In semiconductor manufacturing, a semiconductor manufacturing apparatus such as a stepper (reduction projection exposure apparatus) is used for forming an integrated circuit pattern on a wafer. At this time, the pellicle having the transparent thin film is fixed to a mask for forming a circuit pattern via an adhesive layer formed on the pellicle frame. This can prevent foreign matter from directly adhering to the mask. Therefore, even if foreign matter adheres to the pellicle in the photolithography process,
Since these foreign substances do not form an image on the semiconductor wafer coated with the photoresist, short-circuiting or disconnection of the semiconductor integrated circuit due to the image of the foreign substances can be prevented, and the manufacturing yield of the photolithography process is improved. However, the pellicle is exposed to the g-line (wavelength: 436 nm) and the i-line (wavelength: 365 nm) of a mercury lamp in the photolithography process, so that not only each part constituting the pellicle, that is, the pellicle film but also the pellicle film An adhesive for fixing the pellicle to the pellicle frame and an adhesive for fixing the pellicle to the mask also require light resistance.

[0003] In particular, the pressure-sensitive adhesive layer is formed on the other end surface of the pellicle frame on which the pellicle film is stretched in order to fix the pellicle to the mask, but when the light resistance of the pressure-sensitive adhesive layer is insufficient. This causes serious problems such as the formation of crystalline foreign matter on the pattern surface of the mask due to the generation of gas and volatile components from the adhesive layer due to light deterioration, and the pellicle falling off the mask due to the decrease in adhesive strength due to light deterioration. Or is known to. To cope with such a problem, Japanese Patent Application Laid-Open No. 3-71134 discloses that a hot melt adhesive having a wavelength of 350 to 450 nm and having an absorption of 5% or less is used for a pellicle to cause deterioration over time and degradation due to decomposition. A method for reducing dust is disclosed. Japanese Patent Application Laid-Open No. Hei 4-237056 discloses a block in which diene bonds are reduced by hydrogenating a block copolymer comprising styrene polymers at both ends and a block copolymer comprising butadiene and / or isoprene at a central block. Copolymer,
By using a hot melt adhesive made of aliphatic petroleum resin and liquid paraffin, it is stable to ultraviolet light and can be used under ultraviolet irradiation for a long time. It is disclosed that a pellicle without generation of dust can be obtained.

Further, in recent years, with the development of large-scale integrated circuits, the image line width of integrated circuits is becoming very fine. In fact, the current mainstream of the exposure light source of the stepper is shifting from g-line and i-line to a KrF excimer laser (wavelength is 248 nm) having a short wavelength. The pellicle film, the adhesive (adhesive layer), the pressure-sensitive adhesive (pressure-sensitive adhesive layer), etc. constituting the pellicle in accordance with such a flow are also particularly 3
In the case where ultraviolet light having a wavelength of 00 nm or less, specifically, a KrF excimer laser is used as an exposure light source, it is required to have high light resistance to light having a short wavelength of 248 nm.

[0005] Accordingly, regarding the pressure-sensitive adhesive, acrylic or rubber-based adhesives conventionally used for pellicles for g-rays and i-rays are also used.
Adhesives such as polyamide and polyurethane
Since it has absorption at 48 nm, it cannot be used for a KrF excimer laser. Further, the diblock bond is reduced by hydrogenating a block copolymer composed of a styrene polymer at both ends and a central block composed of butadiene and / or isoprene disclosed in Japanese Patent Application Laid-Open No. Hei 4-237056. The hot-melt adhesive composed of the block copolymer, aliphatic petroleum resin, and liquid paraffin also has no double bond in the center block of the base polymer block copolymer. Since the aromatic double bond still exists and this absorption band extends to 248 nm, it cannot be said that the light resistance to the KrF excimer laser is insufficient.

When the pellicle is fixed to the mask with a silicone adhesive, the silicone adhesive can be used for g-line, i-line,
Furthermore, the pellicle fixed to the mask with a silicone-based adhesive does not fall off the mask even when irradiated with ultraviolet light or excimer laser, because its adhesive strength does not decrease even when irradiated with excimer laser etc. It is disclosed in Japanese Patent Application Laid-Open No. 5-281711 that an advantage is provided. However, in the case of a silicone-based pressure-sensitive adhesive, it has been known that a gas peculiar to polysiloxane is generated by ultraviolet irradiation, and as a result, fogging occurs inside the pellicle film.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photolithography process using light having a wavelength shorter than 300 nm, especially in the pellicle film due to the photodegradation of the pressure-sensitive adhesive layer and the generation of gas accompanying decomposition. There is no fogging of the surface, no crystalline foreign matter is generated on the pattern surface of the mask due to the generation of sublimation components etc. due to such decomposition, and furthermore, the pellicle is removed from the mask by the decrease in adhesive force due to light deterioration. But never fall off,
It is to provide a UV-resistant pellicle.

[0008]

In order to solve the above-mentioned problems, the present inventors have made intensive studies on an ultraviolet-resistant pressure-sensitive adhesive for a pellicle, and as a result, have found that hydrocarbon-based adhesives having an extremely low unsaturated bond content can be obtained. The present inventors have found that the pressure-sensitive adhesive layer satisfies the above-mentioned required characteristics, and have reached the present invention. That is, the first of the present invention
The present invention relates to a pellicle having a pellicle film stretched on one end face of a pellicle frame and an adhesive layer mainly composed of a hydrocarbon compound formed on the other end face, wherein the pressure-sensitive adhesive layer is defined by the following formula (1). The agent layer has a degree of saturation bond S of 0.9 or more and contains 5 to 90% by weight of one or more of block copolymers represented by the following formula (2) or (3). UV resistant pellicle characterized by the following. S = H / (H + L) (1) (in the formula 1, H; the sum of integral values of peaks observed in a region where the value of chemical shift is 0.1 ppm or more and less than 4 ppm in proton NMR measurement of the pressure-sensitive adhesive layer, L Similarly 4pp
(AB) _n -A (2) (AB) _m (3) (where n and m are 1 or more in the formulas 2 and 3) Integer; A; a polymer block composed of a vinyl aromatic or cyclic conjugated diene hydrocarbon monomer, wherein at least 80% or more of all aromatic rings or all olefinic double bonds are hydrogenated; A polymer block comprising a conjugated diene hydrocarbon monomer and at least 90% or more of all olefinic double bonds are hydrogenated) The second invention is used under ultraviolet light having a wavelength in the range of 190 to 300 nm. A UV-resistant pellicle according to the first aspect of the present invention.

[0009]

In a third aspect of the present invention, the polymer block A is made of a styrene monomer and at least 80% or more of the whole aromatic ring is hydrogenated. The ultraviolet-resistant pellicle according to the first invention, wherein the pellicle is made of a butadiene or isoprene monomer and at least 90% or more of all olefinic double bonds are hydrogenated.

In a fourth aspect, the polymer block A comprises 1,3
A cyclohexadiene monomer, wherein at least 80% or more of all olefinic double bonds are hydrogenated, and the polymer block B further comprises 1,
Consisting of 3-butadiene or isoprene monomer,
And at least 90% of all olefinic double bonds
The first is characterized in that the above is hydrogenated.
It is a UV-resistant pellicle according to the invention. A fifth invention is the ultraviolet-resistant pellicle according to any one of the first to fourth inventions, wherein the pressure-sensitive adhesive layer contains a tackifier and a softener in addition to the block copolymer.

Hereinafter, the present invention will be described specifically.
The pellicle film itself used in the present invention may be made of any material, and is not particularly limited. For example, conventionally known nitrocellulose, cellulose acetate propionate, a film obtained from cellulose acetate may be used, but as a pellicle film used in a KrF excimer laser stepper, a copolymer of tetrafluoroethylene and vinylidene fluoride is used. Membrane, terpolymer film of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, and Cytop, a cyclic perfluoroether group-containing polymer (trade name, manufactured by Asahi Glass Co., Ltd.), tetrafluoroethylene "Teflon AF" which is a copolymer of ethylene and a fluorine monomer having a cyclic perfluoroether group (trade name, manufactured by DuPont, USA)
And the like. The pellicle film is formed from a solution of these polymers, and is stretched on one end surface of the pellicle frame via an adhesive suitable for conventionally known materials.

As the pellicle frame material, conventionally known ones can be used, and examples thereof include metals such as aluminum, aluminum alloy, anodized aluminum, and stainless steel. In the present invention, the degree of saturation binding S of the hydrocarbon-based pressure-sensitive adhesive layer formed on one end surface of the pellicle frame is 0.9.
That is all. The saturation bond degree S of the pressure-sensitive adhesive layer in the present invention is an integrated value of absorption in a spectrum obtained when the pressure-sensitive adhesive layer is dissolved in a deuterated solvent for NMR (nuclear magnetic resonance) and subjected to solution proton NMR measurement. Is a value that can be calculated according to the following equation (1). S = H / (H + L) (1) Here, H is tetramethylsilane (TM
In the proton NMR spectrum of the pressure-sensitive adhesive layer with the methyl proton of S) being 0 ppm, 0.1 ppm or more and 4 p
Similarly, L represents the sum of the integrated values of absorption observed in a magnetic field region of 4 ppm or more and less than 10 ppm. The deuterated solvent used for the NMR measurement when calculating the saturation degree S is not particularly limited as long as it can dissolve the pressure-sensitive adhesive layer. For example, deuterides such as chloroform, benzene, toluene, xylene, hexane, heptane, dioxane, cyclohexane, 1,2-dichlorobenzene and dichloromethane are used. If there is solvent absorption that appears when the deuteration of the NMR solvent is incomplete,
It must be excluded from the calculation of the degree of saturation S.

The pressure-sensitive adhesive layer of the present invention is mainly composed of a hydrocarbon compound. Here, the fact that the compound is mainly composed of a hydrocarbon compound means that, when the elemental analysis of the pressure-sensitive adhesive layer is performed, the ratio of the sum of carbon atoms and hydrogen atoms to all elements is 95% by weight or more. The form of the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer in the present invention may be of any type, for example, an organic solvent-type pressure-sensitive adhesive, an aqueous solution-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a solid pressure-sensitive adhesive And the like. However, for those that need to remove the solvent, such as organic solvent-based ones, the process becomes complicated, and for pellicle applications, the presence of residual volatile components such as solvents (organic or aqueous) may be a major problem. is there. From such a viewpoint, a solventless solid pressure-sensitive adhesive is particularly preferable.

Generally, the pressure-sensitive adhesive comprises a base polymer as a main component, and if necessary, a tackifier, a softener,
Although it can be obtained by adding an antioxidant or the like, in the present invention, the base polymer, tackifier, softener, and further antioxidant constituting the pressure-sensitive adhesive layer are saturated with the finally obtained pressure-sensitive adhesive layer. There is no particular limitation on the degree of bonding, as long as the bonding degree S is 0.9 or more and the ratio of the sum of carbon atoms and hydrogen atoms to all elements in the elemental analysis is 95% by weight or more. Hydrogen compounds may be used in combination.

Accordingly, the base polymer used in the pressure-sensitive adhesive layer of the present invention may also be of various types usable for ordinary pressure-sensitive adhesives, as long as the degree of saturation S of the pressure-sensitive adhesive layer can finally satisfy the value specified in the present invention. Can be used as it is, and even if it cannot be used as it is because of a residual unsaturated bond, it can be used by hydrogenating the unsaturated bond. Such base polymers include ethylene, propylene,
Chain or cyclic olefin monomers such as butene, isobutene, cyclohexene, norbornene, etc., chain or cyclic diene monomers such as 1,4-pentadiene, dicyclopentadiene, norbornadiene, 1,3-butadiene, isoprene, 1,3- Pentadiene, 1,3-
Chain conjugated diene monomers such as hexadiene, 1,3-
Cyclopentadiene, 1,3-cyclohexadiene,
Cyclic conjugated diene monomers such as 1,3-cycloheptadiene and vinyl aromatics such as styrene, α-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, p-methoxystyrene, vinylnaphthalene and vinylstyrene Polymers obtained by polymerizing or copolymerizing one or two or more selected from a group of hydrocarbon monomers composed of a series of monomers, or an unsaturated bond (aromatic dimer) contained in those polymers. (Including a heavy bond) obtained by hydrogenation.

The number average molecular weight (by GPC method) of the base polymer used in the present invention is from 5,000 to 5,000.
0000, preferably 10,000 to 1,000,000
00, more preferably 30,000-500,000
Range. When the number average molecular weight is less than 5,000, the pressure-sensitive adhesive layer is soft and inferior in shape retention, and the pressure-sensitive adhesive layer migrates to the adherend during peeling, which is not preferable. On the other hand, when the number average molecular weight exceeds 5,000,000, a remarkable decrease in processability such as extremely low melt fluidity is observed, which is not practically preferable. The number average molecular weight referred to in the present invention is a standard polystyrene equivalent value determined by a GPC (gel permeation chromatography) method in which a base polymer is dissolved in tetrahydrofuran and a moving layer is also made of tetrahydrofuran.

In particular, among the above-mentioned hydrocarbon monomers, one type selected from vinyl aromatic or cyclic conjugated diene type hydrocarbon monomers and one type selected from chain conjugated diene hydrocarbon monomers are mainly used, Since the hydrogenated block copolymer obtained by a method such as a synthetic method has a saturated cyclic hydrocarbon structure, it can be used as a base polymer of an adhesive to provide not only UV resistance but also heat resistance (heat deformation temperature) and creep. A solventless pressure-sensitive adhesive layer having excellent properties can be provided. Examples of such a hydrogenated block copolymer include a block copolymer represented by the following formula (2) or (3). (AB) _n -A (2) (AB) _m (3) Here, n and m represent an integer of 1 or more. n and m
The value of is preferably 1 or more and 6 or less, more preferably 1 or more and 3 or less, since the heat resistance and the creep property of the pressure-sensitive adhesive layer tend to deteriorate when the value becomes large. A represents a polymer block composed of a vinyl aromatic or cyclic conjugated diene hydrocarbon monomer, and at least 80% or more of all aromatic rings or all olefinic double bonds thereof are hydrogenated; It represents a polymer block composed of a conjugated diene hydrocarbon monomer and having at least 90% or more of all olefinic double bonds hydrogenated.

In the present invention, when such a hydrogenated block copolymer having a saturated cyclic hydrocarbon structure is used as a base polymer, its content in the pressure-sensitive adhesive layer is 5 to 90% by weight, Are additives such as tackifiers and softeners. When the content of the base polymer is less than 5% by weight, there is a drawback that elastic recovery at room temperature is insufficient and shape retention is deteriorated. On the other hand, when the content exceeds 90% by weight, tackiness and tackiness are poor, and the role as a pressure-sensitive adhesive cannot be sufficiently fulfilled.

Specific examples of the block copolymer having a saturated cyclic hydrocarbon structure represented by the above general formula (2) or (3) include, for example, a styrene / 1,3-butadiene / styrene triblock copolymer. Styrene / 1,3-butadiene / styrene / 1,3-butadiene-based tetrablock copolymer, styrene / isoprene / styrene-based triblock copolymer, styrene / isoprene / styrene / isoprene-based tetrablock copolymer, etc. And hydrogenated products of the above. In these cases, the hydrogenation rate of all aromatic rings of the polymer block composed of styrene is at least 80% or more, and the hydrogenation of all olefinic double bonds of the polymer block composed of 1,3-butadiene or isoprene is performed. The rate is at least 90% or more.

When 1,3-cyclohexadiene is used as one of the monomer units constituting the block copolymer having a saturated cyclic hydrocarbon structure represented by the general formulas (2) and (3), poly (1,1) Based on the high glass transition temperature (about 240 ° C.) of (3-cyclohexadiene), it becomes possible to provide a pressure-sensitive adhesive layer having extremely excellent heat resistance. Examples of such a block copolymer include 1,3-cyclohexadiene / 1,3-butadiene / 1,3-cyclohexadiene-based triblock copolymer and 1,3-cyclohexadiene / isoprene / 1,3 And hydrogenated cyclohexadiene triblock copolymers. Also in these cases, the hydrogenation rate of all the olefinic double bonds in the polymer block composed of 1,3-cyclohexadiene is at least 80% or more, and the total olefinic content of the polymer block composed of 1,3-butadiene or isoprene is at least 80%. The hydrogenation rate of the double bond is at least 90% or more.

In the case of a block copolymer having a saturated cyclic hydrocarbon structure as represented by the general formulas (2) and (3), for example, a hydrogenated polystyrene block or a hydrogenated poly (1,3-cyclohexadiene) block is used. Since a hydrogenated poly (1,3-butadiene) block or a hydrogenated polyisoprene block acts as a so-called hard segment (referred to as an H unit) and acts as a soft segment (referred to as an S unit), elasticity is exhibited. However, in the present invention, the weight ratio of these two units in the block copolymer is H unit / S unit = 5/9.
5 to 80/20, preferably 10/90 to 60 /
40, more preferably 20/80 to 50/50. If the H unit is less than 5% by weight, only a soft pressure-sensitive adhesive layer having poor creep properties and heat resistance can be obtained. Conversely, if it exceeds 80% by weight, resinous properties become strong and lack elasticity, so that satisfactory adhesive properties can be obtained. It becomes impossible to obtain.

The base polymer of the pressure-sensitive adhesive used in the present invention may be obtained by any production method and is not particularly limited. However, as a method for producing a block copolymer before hydrogenation using styrene or 1,3-butadiene, for example, JP-B-36-1
No. 9286, JP-B-43-14979, JP-B-49-36957, and the like. These use an organic lithium compound as an anionic polymerization initiator in a hydrocarbon solvent, add an ether compound or a tertiary amine, etc., control the amount and mode of side chain bonding of the conjugated diene monomer block, and Depending on the method, epoxidized soybean oil, other functional compounds such as silicon tetrachloride, etc. may be used as a coupling agent to block copolymerize a vinyl aromatic monomer and a chain conjugated diene monomer. Alternatively, a block copolymer having a radial structure is obtained.

Further, when 1,3-cyclohexadiene is used as a block copolymer component, a production method to be particularly noted is disclosed in JP-A-7-247323 and JP-A-7-237733.
-258362. These methods enable living polymerization using a catalyst obtained by combining 1,3-cyclohexadiene with an alkyllithium such as n-butyllithium and an amine such as TMEDA at a specific ratio. The block polymer thus obtained has advantages such as a relatively higher glass transition temperature than those obtained by other methods, and the possibility of various molecular designs by living polymerizability. Is advantageous.

The base polymer used in the pressure-sensitive adhesive of the present invention is copolymerized with the above-mentioned monomer group for the purpose of improving the thermal properties of the pressure-sensitive adhesive layer, compatibility with other additives, processability, crosslinkability, and the like. A small amount of the resulting monomer may be copolymerized. Examples of such a copolymerizable monomer include methacrylates such as methyl methacrylate and butyl methacrylate, and caprolactone. In this case, the copolymerization amount is not limited because the ratio of the sum of carbon atoms and hydrogen atoms to all the elements in the elemental analysis of the pressure-sensitive adhesive layer should be 95% by weight or more. Depending on the type, the UV resistance may be significantly reduced, so that the amount and the type of the copolymer component used must be carefully monitored. In addition, as a form of the copolymer referred to here,
Any form such as random, alternating, block, graft, taper, etc. may be used.

In the present invention, when a base polymer of the pressure-sensitive adhesive layer is formed by subjecting an unsaturated bond portion (mainly an aromatic and olefinic double bond) of a hydrocarbon polymer to a hydrogenation reaction, Is carried out under a hydrogen atmosphere in the presence of a hydrocarbon polymer and a hydrogenation catalyst, and the reaction may be carried out in any conventionally known method, for example, any of a batch system, a semi-batch system, a continuous system, and a combination thereof. Of course, such a hydrogenation reaction is applicable not only to the base polymer but also to the saturation of tackifiers and softeners containing unsaturated bonds.

As the hydrogenation reaction catalyst, any of conventionally known homogeneous catalysts and heterogeneous catalysts can be used.
Although the type and amount are not particularly limited, industrially particularly preferable metals contained in the hydrogenation catalyst include titanium, cobalt, nickel, ruthenium, rhodium, palladium and the like. These metals may be used as a homogeneous catalyst in combination with an organic compound (ligand) having a functional group such as ether, amine, thiol, phosphine, carbonyl, olefin, and diene;
Further, the catalyst may be supported on a carrier such as activated carbon, alumina, barium sulfate, silica, titania, zeolite, or cross-linked polystyrene and used as a heterogeneous catalyst.

Specifically, for example, a metal catalyst such as palladium or rhodium supported on an alumina carrier in a hydrocarbon solvent is added in an amount of 1% by weight to 300% by weight based on the hydrocarbon polymer.
And the reaction temperature is from 120 ° C. to 250 ° C., preferably 1
30 ° C. to 220 ° C., hydrogen partial pressure 2 MPa to 25 MPa,
Preferably, a method of reacting at 3 MPa to 20 MPa is used. After completion of the reaction, it is preferable to separate the catalyst by a known method and to recycle the catalyst.

In the present invention, the hydrogenation rate at the time of hydrogenation of the base polymer and, in some cases, the tackifier and the softener, may be such that the degree of saturation bond S of the pressure-sensitive adhesive layer is finally 0.9 or more. Although not particularly limited, when the base polymer is a block copolymer having a saturated cyclic hydrocarbon structure represented by the following formula (2) or (3), the above The hydrogenation rate is preferably the following value. (AB) _n -A (2) (AB) _m (3) (n and m: an integer of 1 or more, A: a vinyl aromatic or cyclic conjugated diene-based hydrocarbon monomer, and its total aromatic A polymer block in which at least 80% or more of the aromatic ring or all olefinic double bonds are hydrogenated,
B: a polymer block composed of a chain conjugated diene hydrocarbon monomer and having at least 90% or more of all olefinic double bonds hydrogenated therein)

The hydrogenation rate referred to here is the proton NMR
It is calculated using the spectrum. That is,
The integral ratio between the absorption observed in the magnetic field region of 4 ppm or more and less than 10 ppm (olefin proton absorption region) and the absorption observed in the magnetic field region of 0.1 ppm or more and less than 4 ppm (absorption region of protons bonded to saturated carbon) is represented by hydrogen. It can be calculated by comparing before and after the addition reaction. In addition,
Even if the hydrogenation reaction time is shortened, a small amount of unsaturated bond is consciously left in the elastomer, and it is used to improve the thermal and mechanical properties of the adhesive layer by a crosslinking reaction using ultraviolet light or electron beam irradiation. I do not care.

In the present invention, when the adhesive force of the pressure-sensitive adhesive layer is not sufficiently exhibited only by the base polymer, a tackifier is added for the purpose of improving these. In the present invention, conventionally known tackifiers can be used as they are as long as the saturation degree S of the pressure-sensitive adhesive layer finally becomes 0.9 or more, but if necessary, they are hydrogenated. It may be used. The amount is not particularly limited. For example, rosin-based resins and modified rosins, terpene resins and modified terpene resins, petroleum resins, cumarone-indene resins, styrene resins, butyral resins, and the like, and hydrogenated products thereof can be mentioned. Among them, it is particularly preferable to use a hydrogenated terpene resin or an aliphatic or alicyclic petroleum resin from the viewpoint of ultraviolet resistance.

In the pressure-sensitive adhesive layer of the present invention, in order to increase the flowability of the pressure-sensitive adhesive at a high temperature or to improve the processability, the pressure-sensitive adhesive layer according to the present invention has a paraffin within the range of the saturation degree S. Petroleum softeners such as oil, liquid paraffin, process oil and extender oil, and liquid rubber softeners such as polyisobutylene, polybutene and liquid polyisoprene may be added, and the amount thereof is not particularly limited. A conventionally known antioxidant can be added to the pressure-sensitive adhesive layer of the present invention for the purpose of preventing oxidative deterioration during the preparation of the pressure-sensitive adhesive. Examples of such antioxidants include 2,6-di-t-butyl-4-methylphenol and tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl). [Propionate] hindered phenol-based antioxidants such as methane, and other hindered amine-based and benzimidazole-based antioxidants.

If necessary, additives such as conventionally known pigments, fillers and crosslinking agents can be added to the pressure-sensitive adhesive layer of the present invention. In addition, the adhesive of the present invention can be irradiated with ultraviolet rays or electron beams before or after application to the pellicle frame for the purpose of improving mechanical properties (creep properties) and heat resistance. In the present invention, the thickness of the pressure-sensitive adhesive layer formed on one end surface of the pellicle frame is 0.05
To 5 mm, more preferably 0.1 to 2 mm. If the thickness of the pressure-sensitive adhesive layer is less than 0.05 mm, there is a high possibility that the degree of adhesion and sealing with the mask will be insufficient. on the other hand,
If the thickness exceeds 5 mm, the height of the pellicle frame must be reduced because the height of the pellicle is limited, and a problem arises in the strength of the pellicle frame, which is not preferable.

The pellicle of the present invention has a thickness of 190 to 300 nm.
It is particularly preferably used under an ultraviolet ray in the range described above. If the wavelength of the light is shorter than 190 nm, the pressure-sensitive adhesive is significantly deteriorated, which is not preferable. As described above, if a pellicle obtained by forming a hydrocarbon-based pressure-sensitive adhesive layer on one end surface of a pellicle frame with a very small amount or no unsaturated bond as described in the present invention is used, of course, g-line and i-line steppers are used. That is, sufficient practical light resistance can be obtained even for a stepper for a KrF excimer laser. As a result, the inner surface of the pellicle film does not fog due to light deterioration or generation of gas due to decomposition, no crystalline foreign matter is generated on the pattern surface of the mask, and further, the adhesive strength due to light deterioration is reduced. It is possible to provide an ultraviolet-resistant pellicle in which the pellicle does not fall off the mask.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited by these examples. The number average molecular weight of the compound can be determined by a GPC method using a solvent and tetrahydrofuran as a mobile phase (apparatus; TOSO
H HLC-8020, column; Shodex K-8
02 + KF804 + KF805) in terms of standard polystyrene (50 ° C.). The hydrogenation rate of the block copolymer used as the base polymer is 400
MHz high-resolution proton NMR (manufactured by JEOL Ltd .; α-
400) and was calculated from the disappearance of the olefin proton peak. That is, absorption observed in a magnetic field region of 4 ppm or more and less than 10 ppm (olefin proton absorption region) and absorption observed in a magnetic field region of 0.1 ppm or more and less than 4 ppm (absorption region of protons bonded to saturated carbon)
Was calculated by comparing before and after the hydrogenation reaction. The degree of saturation bond S of the pressure-sensitive adhesive layer is obtained when a part of the obtained pressure-sensitive adhesive layer is dissolved in a deuterated solvent for NMR measurement (for example, deuterated toluene) and subjected to solution proton NMR measurement. It was calculated from the integrated value of the absorption in the spectrum according to the following equation (1). The measurement was performed using high-resolution proton NMR (manufactured by JEOL Ltd .; α-400) as described above. S = H / (H + L) (1) Here, H is tetramethylsilane (TM
In the proton NMR spectrum of the pressure-sensitive adhesive layer with the methyl proton of S) being 0 ppm, 0.1 ppm or more and 4 p
Similarly, L represents the sum of the integrated values of absorption observed in a magnetic field region of 4 ppm or more and less than 10 ppm. For the measurement of the sum of carbon atoms and hydrogen atoms by elemental analysis of the pressure-sensitive adhesive layer, YANAGIMOTO; MT-3 type was used.

[0036]

Example 1 (Synthesis of base polymer) In a 40 liter pressure-resistant autoclave, 30 liters of cyclohexane, 30 g of tetrahydrofuran, and 2.7 g of n
-Butyl lithium (n-BuLi), and 6
20 g of styrene (St), 1940 g of 1,3-butadiene (Bd) and 620 g of styrene were sequentially charged,
The polymerization was completed (polymerization temperature 60 ° C.). After the reaction was stopped by adding a small amount of methanol, the reaction solution was poured into a large amount of methanol. After washing the precipitate again with methanol,
Filtration and vacuum drying yielded a styrene / 1,3-butadiene / styrene (St / Bd / St = 20/60/20, wt%) triblock copolymer.

Subsequently, 400 g of the obtained triblock copolymer, 3000 g of cyclohexane, and 100 g of 5% -palladium alumina powder (manufactured by NE Chemcat) were charged into a 5-liter autoclave. The inside is replaced with hydrogen, 150 ° C, hydrogen pressure 5.0MP
A hydrogenation reaction was performed for 5 hours under the condition of a. After 5 hours,
The contents were taken out, the catalyst was filtered off under pressure, reprecipitated with methanol, and dried under vacuum to obtain a hydrogenated product of a styrene / 1,3-butadiene / styrene triblock copolymer.
The hydrogenation rate was 100% for the polybutadiene block and 99.6% for the styrene block, and the number average molecular weight was 1
It was 0.6 × 10 ⁴ .

(Preparation of Pellicle) 100 parts by weight of the above hydrogenated block copolymer, 80 parts by weight of a hydrogenated terpene resin (manufactured by Yasuhara Yushi Co., Ltd.) as a tackifier, and a paraffinic process oil (Idemitsu) as a softener Was melt-mixed in a kneader at 220 ° C. with a kneader to obtain a solid pressure-sensitive adhesive. This was applied at a thickness of 0.3 mm to one end surface of the pellicle frame anodized from a syringe maintained at 150 ° C., the applied surface was flattened, and a pellicle film made of a transparent fluorine film was stretched on the other end surface. I got a pellicle. A part of the pressure-sensitive adhesive was dissolved in deuterated toluene containing TMS and proton NMR measurement was performed to calculate the degree of saturation binding S. As a result, S = 0.993. Also, as a result of elemental analysis,
The ratio of the total of carbon atoms and hydrogen atoms was 99.2% by weight.

(Evaluation of UV resistance) Using a 500 W ultra-high pressure mercury lamp, a total energy of 800 J / cm ² (wavelength 250 nm) was applied to a pellicle attached at 1 kg / cm ² to a quartz glass plate for a mask via an adhesive. Was irradiated with UV light using an illuminometer UV25 manufactured by Oak Co., Ltd., which has the maximum light sensitivity to evaluate the adhesive force, the appearance of the adhesive, and the change over time in the presence or absence of fogging inside the pellicle film. Table 1 shows the results
Shown in

[0040]

Example 2 As the second monomer to be added in the copolymerization reaction, 1940 g was used in place of 1,3-butadiene.
Styrene / isoprene / styrene (St / Ip) in the same manner as in Example 1 except that isoprene (Ip)
/ St = 20/60/20, wt%) based hydrogenated product of a triblock copolymer was obtained. The hydrogenation rate was 99.5% for the polyisoprene block and 99.5% for the styrene block.
The number average molecular weight was 11.4 × 10 ⁴ . A pellicle was prepared using this hydrogenated copolymer in the same manner as in Example 1, and the ultraviolet light resistance was evaluated. Table 1 shows the results. A part of the pressure-sensitive adhesive was dissolved in deuterated toluene containing TMS and subjected to proton NMR measurement, and the degree of saturation binding S was calculated to be S = 0.885. As a result of elemental analysis, the ratio of the total of carbon atoms and hydrogen atoms was 99.0% by weight.
Met.

[0041]

Example 3 After adding purified styrene thirdly in the copolymerization reaction, 970 was added as the fourth monomer.
g of 1,3-butadiene / styrene / styrene in the same manner as in Example 1 except that g of 1,3-butadiene was used.
1,3-butadiene (St / Bd / St / Bd = 15 /
(45/15/25, wt%) hydrogenated product of a tetrablock copolymer. The hydrogenation rate was 98.8% for the poly (1,3-butadiene) block and 98.1% for the styrene block, and the number average molecular weight was 15.2 × 10 ⁴ . A pellicle was prepared using this hydrogenated copolymer in the same manner as in Example 1, and the ultraviolet light resistance was evaluated. Table 1 shows the results. A part of the adhesive was dissolved in deuterated toluene containing TMS, and proton NMR measurement was performed.
Was calculated, and S was 0.982. As a result of elemental analysis, the ratio of the total of carbon atoms and hydrogen atoms was 99.1% by weight.

[0042]

Example 4 10 liters of pressure-resistant autoclave
Liter of cyclohexane, 2.7 g of n-BuLi,
And 5.2 g of N, N, N ', N'-tetramethylethylenediamine (TMEDA) and then 630 g
1,3-cyclohexadiene (CHD), 1940 g
Of 1,3-butadiene and 630 g of CHD were sequentially added to carry out copolymerization (polymerization temperature: 45 ° C.). After the reaction was stopped by adding a small amount of methanol, the reaction solution was poured into a large amount of methanol. The precipitate was washed again with methanol, filtered, and dried under vacuum to obtain 1,3-cyclohexadiene / 1,3.
-Butadiene / 1,3-cyclohexadiene (CHD /
(Bd / CHD = 20/60/20, weight%) based triblock copolymer was obtained.

Subsequently, the obtained triblock copolymer was added to 4
Using 100 g, a hydrogenation reaction was carried out in the same manner as in Example 1,
1,3-cyclohexadiene / 1,3-butadiene /
A hydrogenated product of a 1,3-cyclohexadiene-based triblock copolymer was obtained. The hydrogenation rate was 100% for the polybutadiene block and 98.6% for the 1,3-cyclohexadiene block, and the number average molecular weight was 7.8 × 10 ⁴ . A pellicle was prepared using this hydrogenated copolymer in the same manner as in Example 1, and the ultraviolet light resistance was evaluated. Table 1 shows the results. A part of the adhesive was dissolved in deuterated toluene containing TMS, and proton NMR measurement was performed.
Was calculated as S = 0.983. As a result of elemental analysis, the ratio of the total of carbon atoms and hydrogen atoms was 99.0% by weight.

[0044]

Example 5 In the copolymerization reaction, 1,3-cyclohexadiene / isoprene / 1,1,2-cyclohexadiene / isoprene / 1 was used in the same manner as in Example 4 except that isoprene was used instead of 1,3-butadiene as the second monomer to be added. 3-cyclohexadiene (CHD / Ip / CHD = 20/60/20, weight%)
A hydrogenated triblock copolymer was obtained. The hydrogenation rate was 98.0% for the polyisoprene block and 99.8% for the poly (1,3-cyclohexadiene) block.
And the number average molecular weight was 7.5 × 10 ⁴ . A pellicle was prepared using this hydrogenated copolymer in the same manner as in Example 1, and the ultraviolet light resistance was evaluated. Table 1 shows the results. A part of the pressure-sensitive adhesive was dissolved in deuterated toluene containing TMS and proton NMR measurement was performed to calculate the degree of saturation binding S. As a result, S = 0.980. As a result of elemental analysis, the ratio of the sum of carbon atoms and hydrogen atoms was 98.9% by weight.

[0045]

Comparative Example 1 The styrene / 1, obtained in Example 1
3-butadiene / styrene (St / Bd / St = 20 /
60/20, wt.%) In the same manner as in Example 1 except that the hydrogenation reaction of the triblock copolymer was carried out at 70 ° C.
A hydrogenated product of only the 3-butadiene portion was obtained. The hydrogenation rate was 98.7% for the polybutadiene block and 3.3% for the styrene block, and the number average molecular weight was 10.6 × 1.
0 was ^4. Using this copolymer as a base polymer, a pellicle was prepared in the same manner as in Example 1, and the ultraviolet resistance was evaluated. Table 1 shows the results. Part of this adhesive is TM
It was dissolved in deuterated toluene containing S and subjected to proton NMR measurement, and the degree of saturation binding S was calculated as S = 0.815. As a result of elemental analysis, the ratio of the total of carbon atoms and hydrogen atoms was 98.8% by weight.

[0046]

[Table 1]

[0047]

According to the present invention, the inner surface of the pellicle film can be prevented from fogging due to light deterioration of the pressure-sensitive adhesive layer or generation of gas due to decomposition, particularly in a photolithography process using light having a wavelength shorter than 300 nm. Also, a UV-resistant pellicle that does not generate crystalline foreign matter on the pattern surface of the mask due to the generation of sublimation components and the like due to decomposition and that does not drop off from the mask due to a decrease in adhesive strength due to light deterioration. I got it.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Eiji Honda 1-3-1 Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Asahi Kasei Kogyo Co., Ltd. (56) References JP-A-10-282640 (JP, A) JP-A-4-237056 (JP, A) JP-A-7-258362 (JP, A) JP-A-7-247323 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 1 / 00-1/16

Claims (5)

(57) [Claims] 1. A pellicle comprising a pellicle film stretched on one end surface of a pellicle frame and an adhesive layer mainly composed of a hydrocarbon compound formed on the other end surface, which is defined by the following formula (1). The degree of saturation S of the pressure-sensitive adhesive layer is 0.9 or more.
And the pressure-sensitive adhesive layer is represented by the following formula (2) or (3).
One or more of the block copolymers represented by 5 to 5
An ultraviolet-resistant pellicle comprising 90% by weight . S = H / (H + L) (1) (in the formula 1, H; the sum of integral values of peaks observed in a region where the value of chemical shift is 0.1 ppm or more and less than 4 ppm in proton NMR measurement of the pressure-sensitive adhesive layer, L Similarly 4pp
( AB ) _n -A (2) ( AB ) _m (3) (where n and m are 1 or more in the formulas 2 and 3) Integer, A;
Nyl aromatic or cyclic conjugated diene hydrocarbon monomer
And all aromatic rings or all olefins
At least 80% of hydrogenated double bonds are hydrogenated
Polymer block, B; chain conjugated diene hydrocarbon monomer
And all its olefinic double bonds are small.
At least 90% hydrogenated polymer block) 2. The ultraviolet-resistant pellicle according to claim 1, wherein the pellicle is used under ultraviolet light having a wavelength of 190 to 300 nm. 3. The polymer block A is composed of a styrene monomer and at least 80% of the total aromatic rings thereof are hydrogenated, and the polymer block B is 1,3-butadiene or isoprene. 2. The ultraviolet-resistant pellicle according to claim 1, wherein the pellicle is made of a monomer and at least 90% or more of all olefinic double bonds are hydrogenated. 4. The polymer block A is composed of a 1,3-cyclohexadiene monomer and at least 80% or more of all olefinic double bonds thereof are hydrogenated. 2. The ultraviolet-resistant pellicle according to claim 1, comprising a 1,3-butadiene or isoprene monomer, wherein at least 90% or more of all olefinic double bonds are hydrogenated. 5. The pressure-sensitive adhesive layer according to claim 1, further comprising a tackifier and a softener in addition to the block copolymer.
5. The ultraviolet-resistant pellicle according to any one of items 1 to 4.