KR102032601B1 - Pellicle, photomask with pellicle, and method for manufacturing semiconductor element - Google Patents

Abstract

The present invention comprises a pellicle frame, a pellicle film 3 installed on one end surface 2e of the pellicle frame, and an uncrosslinked acrylic pressure-sensitive adhesive 10 attached to the other end surface 2f of the pellicle frame. It is related with the pellicle whose content of the weight average molecular weight 800 or less compound in the bridge | crosslinking acrylic adhesive 10 is 18 weight% or less. According to this invention, the adhesive residue at the time of peeling a pellicle from a mask can fully be prevented.

Description

PELLICLE, PHOTOMASK WITH PELLICLE, AND METHOD FOR MANUFACTURING SEMICONDUCTOR ELEMENT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle for photolithography which is used to prevent foreign matter from adhering to a mask (photomask) when manufacturing a semiconductor device such as an LSI, an ultra-LSI, or a liquid crystal display panel.

In the photolithography process of semiconductor manufacturing, in order to form the photoresist pattern corresponding to an integrated circuit on a wafer, semiconductor manufacturing apparatuses, such as a stepper (reduced projection exposure apparatus), are used. A pellicle installs a transparent thin film in the one end surface of the pellicle frame which has a frame shape, and prevents a foreign material from adhering directly on a mask and forming the defect of a circuit pattern. Specifically, even if foreign matter adheres to the pellicle in the photolithography step, these foreign matters are not formed on the wafer to which the photoresist is applied. Thereby, short circuit, disconnection, etc. of a semiconductor integrated circuit resulting from the defect of the circuit pattern by the foreign material image can be prevented, and the manufacturing yield of a photolithography process can be improved.

In recent years, with the high integration of a semiconductor device, the shortening of the exposure light used for a photolithography process is progressing. That is, when describing an integrated circuit pattern on a wafer, the technique which can draw a fine circuit pattern with a narrower line width is calculated | required. In order to cope with this, for example, as exposure light of a stepper for photolithography, it proceeds from the conventional g line (wavelength 436 nm) and i line (wavelength 365 nm), and it is KrF excimer laser (wavelength 248 nm), ArF excimer laser. (wavelength 193㎚) also has more of the short wavelength light about to be used, such as F ₂ excimer laser (wavelength 157㎚).

With the recent shortening of wavelength and high energy of exposure light, the frequency of contamination of the pellicle film or mask accompanying exposure increases, and the frequency of replacement of the pellicle and mask is also increasing. Here, as a method of fixing a pellicle on a mask, the method of fixing so that peeling is possible with an adhesive is used normally. As an adhesive, what is acryl type, rubber type, polybutene type, polyurethane type, silicone type, etc. (refer patent document 1), and the thing of thermoplastic elastomer type (refer patent document 2) are known.

Japanese Patent Publication No. 05-281711 International Publication No. 2012-004951

The pressure sensitive adhesive stably has an appropriate adhesive force, and when the pellicle is exchanged, the pressure sensitive adhesive is cohesively broken when peeling the pellicle from the mask so that a part of the pressure sensitive adhesive adheres to the mask (hereinafter, this phenomenon remains the pressure sensitive adhesive). It is desired to prevent). However, with the recent shortening of wavelength and high energy of exposure light, the adhesive described in patent document 1 is easy to combine with a mask by decomposition | disassembly of the adhesive by leaking light, and an adhesive on a mask surface when peeling a pellicle from a mask Pressure-sensitive adhesive residue easily occurs. Moreover, also in the adhesive of patent document 2, in an acrylic adhesive, there exists a subject from a viewpoint of prevention of adhesive residue. In particular, when a short wavelength of 200 nm or less is used, contamination of a mask called haze occurs. Therefore, since the exchange frequency of a pellicle becomes high, it is calculated | required that an adhesive does not remain an adhesive on a mask at the time of peeling from a mask.

In view of the above problems, an object of the present invention is to provide a pellicle, a photomask with a pellicle, and a method for manufacturing a semiconductor element, which can sufficiently prevent adhesive residue when peeling a pellicle from a mask.

The present invention provides the following (1) to (11).

(1) the pellicle frame,

A pellicle film installed at one end of the pellicle frame,

A non-crosslinked acrylic pressure-sensitive adhesive attached to the other end surface of the pellicle frame,

The pellicle whose content of the weight average molecular weight 800 or less compound in an adhesive is 18 mass% or less.

(2) The pellicle as described in (1) whose elasticity modulus of an uncrosslinked acrylic adhesive is 20 mN / mm <2> or more and 180 mN / mm <2>.

(3) The pellicle as described in (1) or (2) whose glass transition temperature of an uncrosslinked acrylic adhesive is less than -25 degreeC.

(4) The pellicle according to any one of (1) to (3), wherein the non-crosslinked acrylic pressure sensitive adhesive contains an acrylic polymer (A) and an acrylic base polymer (B).

(5) The glass transition temperature of acrylic polymer (A) is -30 degrees C or less,

The pellicle as described in (4) whose glass transition temperature of an acrylic base polymer (B) is -25 degreeC or more.

(6) The pellicle as described in (4) or (5) whose content of the acrylic polymer (A) in an uncrosslinked acrylic adhesive is 15-80 mass%.

(7) The pellicle according to any one of (4) to (6), wherein the acrylic polymer (A) is a polymer or copolymer of alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms.

(8) The pellicle according to any one of (4) to (7), wherein the acrylic base polymer (B) is a block polymer.

(9) The block polymer has a structure represented by the following general formula (I) in the polymer main chain,

In formula (I), (a1) and (a2) respectively show a polymer with a glass transition temperature of 80 degreeC or more, (b) the pellicle as described in (8) which shows a polymer with a glass transition temperature of 30 degreeC or less.

(10) (a1) and (a2) in General formula (I) mainly contain the alkyl ester of methacrylic acid of C1-C14, respectively,

The pellicle as described in (9) in which (b) in general formula (I) mainly contains the C1-C14 (meth) acrylic-acid alkylester.

(11) The pellicle according to any one of (4) to (10), wherein the weight average molecular weight of the acrylic polymer (A) is 850 or more and 70000 or less, and the weight average molecular weight of the acrylic base polymer (B) is 10000 or more and 500000 or less.

(12) The photomask with a pellicle in which the pellicle in any one of (1)-(11) is attached.

(13) The manufacturing method of a semiconductor element provided with the process of exposing a board | substrate with the photomask with a pellicle as described in (12).

According to this invention, the adhesive residue at the time of peeling a pellicle from a mask can fully be prevented.

1 is a perspective view illustrating a pellicle according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1. FIG.
It is a figure which shows typically the process of exposing a board | substrate with the pellicle photomask which concerns on one Embodiment of this invention.

 EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention (henceforth simply a "this embodiment") is demonstrated in detail. This embodiment below is an illustration for demonstrating this invention, and is not the meaning which limits this invention to the following content. The present invention can be appropriately modified within the scope of the gist of the invention.

1 is a perspective view illustrating a pellicle according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1. As shown in FIG. 1 and FIG. 2, the pellicle 1 includes a pellicle frame 2, a pellicle film 3 mounted on one end surface 2e of the pellicle frame 2, and a pellicle frame 2. It is provided with the adhesive 10 adhered to the other end surface 2f of this, and the protective film F which adheres to the adhesive 10, and protects this adhesive 10. As shown in FIG. 3 is a diagram schematically illustrating a step of exposing a substrate by the photomask with pellicle according to the present embodiment. As shown in FIG. 3, the pellicle photomask 30 of this embodiment is equipped with the pellicle 1 and the photomask 20. As shown in FIG. The other end surface 2f of the pellicle 1 is attached to the end surface 20f on the side where the pattern 20P of the photomask 20 is formed via the adhesive 10. In order to expose the board | substrate 60, the exposure light 40 is irradiated to the said photomask 30 with a pellicle from above the photomask 30 with a pellicle. After passing through the photomask 30 with a pellicle, the exposure light 40 is condensed by the light transmission optical system 50, and is irradiated to the board | substrate 60 with the photoresist 62 provided in the surface. Then, the pattern 20P of the photomask 20 is transferred to the surface of the board | substrate 60 by passing through predetermined processes, such as a developing process and an etching process. Substrate 60 includes, for example, a semiconductor material. As mentioned above, the process of transferring the pattern 20P of the photomask 20 to the surface of the board | substrate 60 using the photomask 30 with a pellicle is a part of the manufacturing process of a semiconductor element, for example.

(adhesive)

The adhesive (acrylic adhesive) used for the pellicle which concerns on this embodiment is an uncrosslinked acrylic adhesive material, and the content rate of the compound of the weight average molecular weight 800 or less in an acrylic adhesive is 18 mass% or less. The non-crosslinking type here includes the case where the reaction product with a hardening | curing material is included in the range which exhibits the effect of this invention.

Moreover, it is preferable that the glass transition temperature of the acrylic adhesive of this embodiment is less than -25 degreeC, It is more preferable that it is -27 degrees C or less, It is further more preferable that it is -30 degrees C or less. In the case where the acrylic pressure-sensitive adhesive of the present embodiment has a plurality of glass transition temperatures, at least one of the plurality of glass transition temperatures may be present in this range. When the glass transition temperature is in the above-described range, the elastic modulus is low and thus a soft adhesive can be more effectively exhibited. Moreover, although the minimum in particular of the glass transition temperature of the acrylic adhesive of this embodiment does not have a restriction | limiting, It is preferable that it is -90 degreeC or more from a viewpoint of the ease of handling and the moldability of a mask adhesive.

Moreover, it is preferable that the elasticity modulus of the acrylic adhesive of this embodiment is 20 mN / mm <2> or more and 180 mN / mm <2> or less. When the modulus of elasticity is within the above range, the pellicle shift from the mask can be suppressed while maintaining the softness, and the adhesion load applied to the mask can be alleviated, so that the strain applied from the pellicle to the mask can be reduced. As for the elasticity modulus of the acrylic adhesive of this embodiment, it is more preferable that they are 30 mN / mm <2> or more and 160 mN / mm <2> or less, and it is more preferable that they are 40 mN / mm <2> or more and 140 mN / mm <2> or less. The elasticity modulus of an adhesive can be adjusted in consideration of their compatibility, when using the elasticity modulus of the raw material polymer used for an adhesive, and a some raw material polymer.

In addition, it is preferable that the acrylic adhesive used for the pellicle which concerns on this embodiment contains an acrylic polymer (A) and an acrylic base polymer (B) from a viewpoint of providing favorable elastic adhesiveness. Here, the weight average molecular weights of the said compound etc. are the values obtained by the GPC (gel permeation chromatography) measurement.

(Compound with a weight average molecular weight of 800 or less)

A compound with a weight average molecular weight of 800 or less is used as a tackifier for expressing adhesiveness or improving adhesive and adhesive performance in an uncrosslinked acrylic adhesive. The tackifier not only has good compatibility with the polymer (base polymer) serving as the base of the pressure-sensitive adhesive, but also needs to give the pressure-sensitive adhesive with excellent viscosity flow characteristics, i.e., a property of instantly bonding at a rate of deformation or fluctuation of the pressure-sensitive adhesive. It is important that the molecular weight is significantly lower than the polymer. Therefore, a low molecular weight compound with a weight average molecular weight of 800 or less is usually used as a tackifier.

As mentioned above, the content rate of the compound of the weight average molecular weight 800 or less in an adhesive is 18 mass% or less. When the content ratio of the compound having a weight average molecular weight of 800 or less is within the above range, the compound is properly prevented from leaking onto the surface of the pressure-sensitive adhesive. Thereby, aggregation failure of an adhesive can be suppressed and adhesive residue can be reduced. It is more preferable that there are few content rates of the said compound, and it is more preferable that they are 15 mass% or less, 10 mass% or less, 7 mass% or less, or 3 mass% or less. Although the said compound may not be contained in the adhesive, the content rate of the said compound in the case where the said compound is contained in an adhesive may be 0.5 mass% or more, or 1 mass% or more.

In addition, the acrylic adhesive in the prior art is largely divided into a crosslinking type and a non-crosslinking type adhesive. Generally, in the case of an uncrosslinked acrylic pressure sensitive adhesive, the base polymer and the tackifier are contained. Examples of the tackifier include rosin-based resins, terpene-based resins, petroleum-based resins, and the like, and have a molecular weight of several hundred to several thousand and are amorphous compounds. The tackifier applied most to an acrylic adhesive becomes a rosin-type resin. Since the rosin-based resin has a three-dimensional and bulky cyclic structure, it has a narrow molecular weight distribution with a low molecular weight compared to other petroleum resins having the same softening point. Moreover, rosin-type resin has most polar groups, such as an ester bond, and is the most applied as a tackifier of an acrylic adhesive from the point which is excellent in compatibility with a base polymer. However, since rosin-type resin contains the structure which has an unsaturated bond substituted by abienic acid, it is easy to be oxidized and its light resistance etc. are inferior. Therefore, the rosin derivative which is excellent also for optical use etc. is developed by the development of resin which esterified hydrogenated and superposed | polymerized modified rosin, and the super-bleaching technique.

In the conventional acrylic adhesive, the amount of 20 mass% or more and 80 mass% or less is mix | blended with a base polymer in order to make a base polymer and a tackifier compatible, and to express adhesiveness and rubber elasticity. This is because generally, when the tackifier is less than 20 mass%, it is said that the improvement of adhesiveness is lacking. However, when a tackifier is made into the said content rate, separation etc. generate | occur | produce between a tackifier and a base polymer. For this reason, a tackifier comes out to the surface, and a tackifier moves to a mask side and remains on a mask side. It is thought that this is one of the causes of adhesive residue generation when using a conventional acrylic adhesive.

(Acrylic Polymer (A))

The glass transition temperature of an acrylic polymer (A) is -30 degrees C or less, it is preferable that it is -33 degrees C or less, and it is more preferable that it is -35 degrees C or less. By the glass transition temperature of an acrylic polymer (A) being -30 degrees C or less, even when an environmental temperature is low, it has favorable elastic adhesiveness and workability becomes favorable. Although a minimum does not have a restriction | limiting in particular, It is preferable that glass transition temperature is -90 degreeC or more from the ease of handling and the availability. In addition, when an acrylic polymer (A) has some glass transition temperature, at least 1 of the said some glass transition temperature should just exist in the said range, and it is preferable that all the said plurality of glass transition temperatures exist in the said range. In addition, glass transition temperature, such as a compound used for this embodiment, is a value obtained by DSC (differential scanning calorimetry).

When glass transition temperature is the said range, since an acrylic polymer (A) turns into a liquid at normal temperature, it is easy to handle. In addition, by using an acrylic polymer (A), even if conventional tackifiers, such as rosin-type resin, are not mix | blended with an acrylic adhesive, the adhesive force which can be used as an adhesive of a pellicle can be expressed. It is thought that this is because compatibility with the monomer component which has adhesiveness and flexibility contained in an acrylic base polymer (B) becomes favorable by using an acrylic polymer (A). Moreover, since acrylic polymer (A) has good compatibility with acrylic base polymer (B), since it is hard to phase-separate and becomes light resistance, the ratio which soaks on the surface like a conventional tackifier becomes small, and it is an adhesive The adhesive residue of is suppressed.

Moreover, with the recent shortening of wavelength and high energy of exposure light, refinement | miniaturization of a pattern is progressing. Double patterning is known as a method of refinement | miniaturization, and it exposes normally twice using two masks. For this reason, it becomes important to raise the positional precision of the two patterns formed. In other words, if the positional accuracy of the pattern obtained by the first exposure and the pattern obtained by the second exposure is low, the desired pattern cannot be obtained. For this reason, since the positional shift of the two patterns formed needs to be made small, the flatness calculated | required by the mask is needed. At this time, when a pellicle is affixed to a mask, mask deformation may occur.

As one of the causes of this mask deformation | transformation, when a pellicle is crimped | bonded to a mask through an adhesive, it is thought that the deformation of a pellicle frame is transmitted through an adhesive. Therefore, in order to prevent the deformation of the pellicle frame from being transmitted to the mask, it is considered that by softening the pressure-sensitive adhesive, the deformation energy of the pellicle frame is alleviated, and as a result, the mask deformation is reduced. If the glass transition point of an acrylic polymer (A) is in the said range, since compatibility with an acrylic base polymer (B) is favorable, flexibility can be exhibited. As a result, the above-described mask deformation can be reduced.

It is preferable that content of the said acrylic polymer (A) is 15-80 mass% with respect to the whole adhesive. It is more preferable that it is 18-75 mass%, It is further more preferable that it is 20-70 mass%, It is especially preferable that it is 30-70 mass%, It is especially more preferable that it is 40-70 mass%. When the said content is 15 mass% or more, appropriate adhesive force can be obtained, and when it is 80 mass% or less, cohesion force can be made into an appropriate range, and a holding force improves. By making content of an acrylic polymer (A) into the said range, it can prevent that a pellicle falls from a mask after affixing a pellicle to a mask.

The acrylic polymer (A) preferably contains an alkyl (meth) acrylate polymer or copolymer having an alkyl group having 1 to 14 carbon atoms from the viewpoint of having a role as a softener. These polymers or copolymers also include diblocks, triblocks, and the like, polymerize one or two or more alkyl (meth) acrylate monomers, or one or two or more alkyl (meth) acrylate monomers ( It is obtained even if it superposes | polymerizes the mixture of other monomers other than an alkyl meth) acrylate type monomer. Moreover, depending on the functionality, the acrylic polymer (A) may be obtained using one kind or two or more kinds of these polymers or copolymers. In addition, "(meth) acrylic acid" in this specification means "acrylic acid" and "methacrylic acid" corresponding to it.

As a specific example of the alkyl (meth) acrylate type monomer, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate (octyl acrylate), (meth) acrylic acid Decyl, 2-ethylhexyl (meth) acrylate, isobutyl (meth) acrylate, isooctyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid, hydroxyethyl (meth) acrylate, (meth) acrylate (Meth) acrylic acid ester of linear aliphatic alcohol, such as oxypropyl, glycidyl (meth) acrylate, and methoxyethyl acrylate, or (meth) acrylic acid ester which has a branched alkyl chain, etc. are mentioned. Moreover, as said other monomer, the monomer copolymerizable with an alkyl (meth) acrylic-type monomer, for example, acrylic acid, vinyl acetate, styrene, etc. can be used.

Especially, butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, The polymer or copolymer formed from (meth) acrylic-acid alkylester which has a C1-C8 alkyl group, such as isobutyl (meth) acrylate, is compatible with the monomer component which can express the adhesiveness of an acrylic base polymer (B). It is preferable because it is easy to have sex. Moreover, the polymer or copolymer mentioned above can also have a role as a softener.

It is preferable that it is 850 or more and 70,000 or less in a weight average molecular weight, and, as for the molecular weight of an acrylic polymer (A), it is more preferable that it is 900 or more and 68,000 or less. When the weight average molecular weight of an acrylic polymer (A) is 850 or more, sufficient adhesive strength is obtained, A viscosity can be controlled to an appropriate range by being 70,000 or less, and it is preferable from a viewpoint of making workability favorable.

Moreover, when a weight average molecular weight is 850 or more and 70,000 or less, it becomes easy to be compatible with an acrylic base polymer (B). For this reason, it becomes possible to raise the adhesiveness of an acrylic base polymer (B), and it becomes possible for an acrylic polymer (A) to also act as a tackifier. Moreover, even when the compound of molecular weight 800 or less is made into 18 mass% or less, while the adhesive force of an adhesive is exhibited favorably, it becomes possible to improve adhesive residue.

The average molecular weight of the acrylic polymer (A) is preferably from the viewpoint of preventing the adhesive residue from having a M _W / M _N in the range of 1.0 to 2.0. Moreover, it is preferable that it is a block polymer from a viewpoint that it becomes possible to apply | coat an adhesive to a pellicle frame thickly and to reduce the mask distortion at the time of sticking a pellicle to a mask.

As a specific example of an acryl-type polymer (A), a brand name "Arupon (ARUFON) (trademark)" series (made by Toagosei Co., Ltd.), a brand name "Craiti (registered trademark)" series (made by Kuraray Co., Ltd.), etc. are mentioned. Can be mentioned. Trade name "Aru phone (trademark)" series, the polymerization initiator, as a chain transfer agent, does not use a solvent such as less impurities, since M _W / M _N is the molecular weight distribution is narrow as 1.0 to 2.0, the pressure-sensitive adhesive residue prevention property in particular great. Moreover, since the brand name "Cryrity (trademark)" series is a triblock copolymer having a hard segment and a soft segment, the reduction of mask deformation is particularly excellent in that it can be thickly applied to a pellicle frame. Further, since the commercial name "Priority Klein TM" series of narrow molecular weight distribution with M _W / M _N of 1.0 to 2.0, it is excellent in pressure-sensitive adhesive residue prevention.

(Acrylic Base Polymer (B))

In this embodiment, it is preferable that an acrylic base polymer (B) is -25 degreeC or more and 140 degrees C or less of glass transition temperature. Especially -25 degreeC or more and 130 degrees C or less, and -25 degreeC or more and 120 degrees C or less are preferable. In the case where the acrylic base polymer (B) of the present embodiment has a plurality of glass transition temperatures, at least one of the plurality of glass transition temperatures may be present in this range. Moreover, it is preferable that an acrylic base polymer (B) is block polymer from a viewpoint which becomes possible to apply | coat an adhesive thickly to a pellicle frame, and to reduce mask distortion at the time of sticking a pellicle to a mask.

It is preferable that glass transition temperature is -25 degreeC or more, and, as for the said block polymer, it is preferable that it is 140 degrees C or less. In particular, -10 degreeC or more and 130 degrees C or less, and 0 degreeC or more and 120 degrees C or less are preferable.

The block polymer includes the general formulas (I)-(a1)-(b)-(a2)-. It is preferable that the glass transition temperatures of (a1) and (a2) of Formula (I) are 80 degreeC or more. It is preferable that the glass transition temperature of (b) of Formula (I) is 30 degrees C or less. Moreover, it is preferable that (b) of Formula (I) is a block polymer which has a polymer whose glass transition temperature is 30 degrees C or less in a main chain.

The monomer component which comprises the polymer block represented by (a1) and (a2) of Formula (I) (henceforth these polymer blocks are called "polymer block a") is a C1-C14 alkyl methacrylate mainly It is preferable that it is ester from a viewpoint of making the glass transition temperature of the polymer block a into 80 degreeC or more. As said alkyl methacrylate, For example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid sec-butyl, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, meta 1 type (s) or 2 or more types, such as lauryl krill, tridecyl methacrylate and 2-hexyl decyl methacrylate, is mentioned. However, methacrylic acid, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and carbon number 3 or less from a viewpoint of making the glass transition temperature of the polymer block a into 80 degreeC or more. It is more preferable to mainly use ester containing alcohol. Here, "mainly" means that the methacrylic acid alkyl ester having 1 to 14 carbon atoms occupies at least half of the entire polymer block a, and preferably 80% or more. In addition, at least any one of polymer block a may contain the C1-C14 methacrylic acid alkylester.

In the polymer block a of formula (I), if it is a small ratio (for example, less than half, preferably less than 20%), for example, trimethylsilyl methacrylate, trimethoxy silylpropyl methacrylate, and methacrylate Methacrylic acid esters other than alkyl esters such as cydyl and allyl methacrylate; Alkyl acrylates such as methyl acrylate, n-butyl acrylate and t-butyl acrylate; Olefins such as ethylene and propylene; The structural component derived from the monomer called lactone, such as (epsilon) -caprolactone and valerolactone, may be contained. If the glass transition temperature of the polymer block a is 80 degreeC or more, the holding force and cohesion force under high temperature are fully obtained and it is preferable.

The monomer component which comprises the polymer block (henceforth this "polymer block b") represented by (b) of Formula (I) is mainly C1-C14 alkyl acrylate and / or alkyl methacrylate. It is preferable from a viewpoint of making the glass transition temperature of the polymer block b into 30 degrees C or less. As alkyl acrylate ester which can comprise the polymer block b, For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, 1 type (s) or 2 or more types, such as amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate. Moreover, as methacrylic acid alkylester monomer which can comprise the polymer block b, For example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate Isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Pentadecyl, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyl decyl methacrylate, etc. can be mentioned. However, in the case of constituting the polymer block b using the alkyl methacrylate as the main monomer component, in order to make the glass transition temperature 30 ° C. or less, n-butyl methacrylate, isobutyl methacrylate, and meta Amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, 2-hexyl methacrylate, etc. It is preferable to mainly use esters of methacrylic acid and an alcohol having 4 or more carbons. The polymer block b may include other constituents within a range that does not adversely affect the pressure-sensitive adhesive residue and the light resistance of the mask.

When the glass transition temperature of the polymer block b is 30 degrees C or less, since adhesive force and holding force are fully obtained, it is preferable.

The block polymer has a structure in which one polymer block b is located between two polymer blocks a, as shown in formula (I) and (a2). However, if the above-described three polymer blocks are included in a predetermined order, not only a block copolymer composed of these three polymer blocks but also a block composed of four or more polymer blocks including one or more other polymer blocks It may also contain a copolymer. The other polymer block mentioned above may be a polymer block of the same kind as polymer block a or b, and may be a polymer block c different from it. As another polymer block c, the polymer block comprised by olefins, such as ethylene and a propylene, and lactones, such as (epsilon) -caprolactone and a valerolactone, is illustrated.

Preferred block copolymers in this embodiment include polymer block a-polymer block b-polymer block a, polymer block a-polymer block b-polymer block a-polymer block b, polymer block a-polymer block b-polymer block a A polymer block c and the like.

It is preferable that the molecular weight of a block copolymer exists in the range of 10,000-500,000 by weight average molecular weight, and it is more preferable to exist in the range of 30,000-450,000, especially 50,000-400,000. When the weight average molecular weight of a block copolymer is the range of 10,000-500,000, it can superpose | polymerize by a living polymerization method etc., and the block copolymer with a small molecular weight distribution and few impurities is obtained. It is preferable at this point that the adhesive residue of an adhesive improves and it becomes possible to apply | coat an adhesive thickly. Further, in view of the above, as the molecular weight distribution it is preferably a M _W / M _N of 1.0 to 2.0.

And in a block copolymer, the ratio (a / b) of the total mass of the polymer block a in the case where it is based on the total mass of the polymer block b contained in a molecule | numerator is preferable in it being 5/95-80/20. Furthermore, a / b is more preferable in it being 10/90-75/25. When a / b is 5/95 or more, the cohesion force of an adhesive is fully acquired and it becomes the tendency for a high holding force to be obtained. Moreover, since a / b is 80/20 or less, it becomes the tendency for adhesive force to fully be obtained.

If it is the block copolymer mentioned above, the side chain which has a bulky branched structure in a polymer can be formed. For this reason, it becomes possible to apply | coat an adhesive thickly and it becomes possible to reduce mask distortion at the time of sticking a pellicle to a mask. Moreover, since an acrylic polymer (A) has especially favorable compatibility with the polymer block b, adhesiveness and flexibility can be improved and mask deformation can be reduced further.

Further, the block copolymer has functional groups such as hydroxyl groups, carboxyl groups, acid anhydride groups and amino groups in the molecular side chain or at the terminal of the molecular main chain to the extent that the adhesive residue in the mask and the light resistance of the acrylic base polymer (B) are not adversely affected. You may have it.

As a specific example of these block copolymers, a brand name "Crity (registered trademark)" series (made by Kuraray Co., Ltd.), a brand name "Nanostrength" series (made by Arkema Co., Ltd.), etc. are mentioned.

In addition to these acrylic polymers (A) and acrylic base polymers (B), an inorganic substance may be added for the purpose of improving the light resistance and improving the adhesive residue.

The pellicle of this embodiment can be manufactured suitably by the following method, for example.

First, the acrylic polymer (A) and the acrylic base polymer (B) described above are mixed to obtain an adhesive composition. In this case, since the adhesive 10 is attached (coated) to the end surface of the pellicle frame 2 as a mask adhesive layer of a predetermined thickness and width, the adhesive composition is diluted again with a solvent to adjust the solution concentration (viscosity). do. As for the thickness of a mask adhesive layer, 0.25 mm or more and 3.0 mm or less are preferable. In the semiconductor, the thickness is preferably 0.25 mm or more and 1.0 mm or less, and more preferably 0.3 mm or more and 0.8 mm or less. In liquid crystal use, the thickness is preferably 1.0 mm or more and 2.5 mm or less, and more preferably 1.2 mm or more and 2.0 mm or less. Moreover, 30% or more and 90% or less of the frame width to which the mask adhesive layer is apply | coated is preferable, and 40% or more and 80% or less are more preferable. As frame width, 1.0 mm or more and 20 mm or less are common.

Second, the pressure-sensitive adhesive composition is applied to the other end surface 2f of the pellicle frame 2 having the pellicle film 3 installed on one end surface 2e. Although a coating method is not specifically limited, When diluting an adhesive composition with a solvent, it is preferable to apply | coat using a dispenser or a syringe. Moreover, the hot melt method which heat-melts an adhesive composition and apply | coats can also be used.

Third, when the pressure-sensitive adhesive composition is diluted with a solvent, the molded pressure-sensitive adhesive 10 is brought into close contact with the other end surface 2f of the pellicle frame 2 by heating and drying the applied pressure-sensitive adhesive composition. When apply | coating an adhesive composition by a hot melt method, the adhesive 10 which cooled after shape | molding the apply | coated adhesive composition is made to adhere to the other end surface 2f of the pellicle frame 2 closely. After drying or cooling an adhesive composition, you may stick the protective film F for protecting the adhesive face of the adhesive 10. As the protective film F, for example, a film having a thickness of 30 to 200 μm made of polyester is used. Moreover, when the peeling force at the time of peeling the protective film F from the adhesive 10 is large, there exists a possibility that the adhesive 10 may deform | transform at the time of peeling. Therefore, you may perform previously the mold release process using silicone or fluorine etc. on the protective film F surface which contact | connects the adhesive 10 so that it may become a suitable peeling force.

After sticking the protective film F for protecting the adhesive face of the adhesive 10, weighting is added and the adhesive surface may be shape | molded substantially flat.

Example

Hereinafter, although an Example and a comparative example demonstrate this embodiment further more concretely, this embodiment is not limited at all by these.

The following things were used for the acryl-type polymer (A), the acryl-type base polymer (B), and the compound of molecular weight 800 or less. In addition, about an acrylic polymer (A), the ratio of the molecular weight 800 or less of the composition obtained by GPC measurement is shown together. (Acrylic Polymer (A))

ALPON (registered trademark) UP1190 (made by Toagosei Co., Ltd.) (28.2%)

(Glass transition temperature: -50 ℃)

Arupon (registered trademark) UP1080 (manufactured by Toagosei Co., Ltd.) (5.9%)

(Glass transition temperature: -61 ℃)

ALPON (registered trademark) UP1000 (made by Toagosei Co., Ltd.) (13.7%)

(Glass transition temperature: -77 ℃)

Clarity (registered trademark) LA1114 (manufactured by Kuraray, Inc.) (0.0%)

(Glass transition temperature: -40 ℃)

I-BA / BA / AA / HEA (isobutyl acrylate / butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate) (2.4%)

(Glass transition temperature: -51 ℃)

(Acrylic Base Polymer (B))

Clarity (registered trademark) LA2140e (product made by Kuraray Co., Ltd.)

(Glass transition temperature: -38 ℃, 85 ℃)

Clarity (registered trademark) LA2330 (manufactured by Kuraray Co., Ltd.)

(Glass transition temperature: -39 ℃, 86 ℃)

Nanostrength M-85 (made by Arkema Co., Ltd.)

(Glass transition temperature: -54 ℃, 100 ℃)

(Compound with a molecular weight of 800 or less)

Fine Crystal (registered trademark) KE-311 (made by Arakawa Kagaku Kogyo Co., Ltd.)

Measurement of the molecular weight, glass transition temperature, and content of each copolymerization component of the acrylic polymer (A) and the acrylic base polymer (B), the glass transition temperature and the elastic modulus of the pressure-sensitive adhesive containing the acrylic polymer (A) and the acrylic base polymer (B) It carried out according to the apparatus and conditions described below.

(1) Molecular weight measurement by GPC (gel permeation chromatography)

Apparatus: gel permeation chromatography (HLC-8320) manufactured by Tosoh Corporation

Column: Connect "TSK gel SUPER HZ3000 x 2" and "HZ 2000 x 2" manufactured by Tosoh Corp. in series

Eluent: tetrahydrofuran

Eluent flow rate: 0.6 ml / min

Column temperature: 40 ℃

Detector: differential refractive index (RI) meter

Calibration curve: Created using standard polystyrene

(2) Glass transition temperature measurement by DSC (differential scanning calorimetry)

Apparatus: DSCQ2000 made by TA Instruments

· Sealed fan

Temperature range: -80 ° C to 160 ° C

Heating rate: 5 ℃ / min

Sample weight: 10 mg

 When two or more glass transition temperatures of the adhesive containing an acrylic polymer (A) and an acrylic base polymer (B) were measured, it showed in Table 1 as the temperature of the lowest temperature side as glass transition temperature Tg.

(3) Proton nuclear magnetic resonance ⁽¹ H-NMR) measurement of the content of the by spectroscopy, each copolymer component

Apparatus: nuclear magnetic resonance apparatus (JNM-LA400) made by Nippon Denshi Corporation

Solvent: Heavy Chloroform

In the ¹ H-NMR spectrum, the signals in the vicinity of 3.6 ppm and 4.0 ppm are ester groups (-O-CH ₃ ) of methyl methacrylate units and ester groups -O-CH of n-butyl acrylate units, respectively. ₂ -CH ₂ -CH _2, because it is attributed to -CH _3), was determined the content of the copolymer component by the ratio of the integrals of these signals.

(4) measurement of elastic modulus

One side of the pellicle having the protective film was cut off, and then the protective film was slowly peeled off so that the pressure-sensitive adhesive layer was not deformed, and then the mask pressure-sensitive adhesive layer was slowly peeled off from the pellicle frame. In that case, when it was difficult to peel, it peeled slowly, attaching a cica roll to a hand and an adhesive layer, and made the elongation rate of the peeled adhesive layer become 5% or less.

The peeled adhesive layer was measured at room temperature (25 degreeC) using the following apparatus.

Device name: Autograph (SHIMAZU EZ-S Shimadzu Seisakusho)

Load cell: 1 N (clip chuck)

Spindle: 40mm

Cross head speed: 100 mm / min.

The pressure-sensitive adhesive layer was stretched to 20% elongation with the above apparatus. Separately, the cross-sectional area of the pressure-sensitive adhesive layer was measured, and the stress value per unit area was determined by dividing the measurement result by the cross-sectional area.

A graph including the elongation on the x-axis and the stress value per unit area on the y-axis was created, and the value of the y-axis at 100% elongation when a straight line was drawn at 0% elongation and 20% elongation was used as the elastic modulus.

(Adjustment of i-BA / BA / AA / HEA Composition)

The i-BA / BA / AA / HEA composition was adjusted by a well-known 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 inlet tube, and isobutyl acrylate / butyl acrylate / acrylic acid / 2-hydroxyethyl acryl A mixture of rate / 2,2′-azobisisobutyronitrile (32 parts by weight) was added at a weight ratio of 48/48 / 1.5 / 2.5 / 1.0, and the reaction solution was reacted at 60 ° C. for 8 hours under a nitrogen atmosphere. do. Toluene (38 weight part) was added after completion | finish of reaction, and the acrylic copolymer solution of 32 weight% of non volatile matter concentration was obtained.

<Example 1>

(Production of pellicle)

70 mass parts of "credit LA1114 (made by Kuraray)" as an acrylic polymer (A), and an acrylic block copolymer "credit LA2140e (made by Kuraray)" as a base acrylic polymer (B) 30 The mass part was mixed so that it might be set to 48 g as a whole, and the raw material mixture was obtained. The obtained raw material mixture was thrown into the labo plasterto mill (Toyo Seki Seisakusho make, content: 60 mL), and it sealed. It knead | mixed for 20 minutes at 200 degreeC and 100 rpm, and obtained the bulk mask adhesive. About 10 g of mask adhesive was poured into a heating tank (tank temperature: 200 ° C) to melt.

On the other hand, a pellicle frame made of anodized aluminum alloy (outer diameter 113 mm x 149 mm, inner diameter 109 mm x 145 mm, height 2.9 mm) was prepared. Here, four jig holes with a hole diameter of 1.6 mm and a depth of 1.2 mm were formed at positions 25 mm from the corner portions of the outer side of the pellicle frame at positions that became 1.7 mm from the film adhesive-coated end face as pin holes. . The mask adhesive of the molten state extruded from the needle tip connected to the heating tank was apply | coated on one end surface of the pellicle frame, and the mask adhesive layer was formed. The thickness of the formed mask adhesive layer was 0.6 mm. Then, the protective film made from polyester of 100 micrometers in thickness which carried out the silicone mold release process was bonded to the surface of a mask adhesive layer. A pellicle was produced by attaching a pellicle film to the other end surface of the pellicle frame through a film adhesive layer.

Peelability evaluation and deformation | transformation evaluation of the mask were performed about the obtained pellicle. Each result is shown in Table 1.

(Exfoliation evaluation)

About the pellicle which has the adhesive obtained in Example 1, the protective film was peeled off and it attached to the mask blank base material which has 6025 chromium by weighting (30Kgf, 60sec) with the simple mounter, and the mask base material with a pellicle was obtained. After leaving the mask substrate at room temperature (20 ± 3 ° C.) for 2 hours, the mask substrate is fixed horizontally, and a tensile tester is used to grasp a total of four pin holes, each of which is located on each of the two long sides of the pellicle, and a total of four long holes. At the same time, the sides were pulled up at a speed of 5 mm / min perpendicular to the mask surface, and the pellicle was peeled off. Peelability observed the state of each adherend surface, and evaluated the following references | standards. The pressure sensitive adhesive residue in the present embodiment means that a part of the pressure sensitive adhesive adheres to the mask by cohesive failure.

(Double-circle): An adhesive residual area is 0% or more and 5% or less of the whole adhesion area.

○: The adhesive residual area is more than 5% and 10% or less in the entire adhesion area.

(Triangle | delta): The adhesive residual area is more than 10% of 20 whole adhesion areas, or less

X: adhesive residual area is more than 20% in 100% of the whole adhesion area, or less

(Evaluation of mask deformation)

Evaluation of the deformation by deformation of the mask or the like was measured using a FlatMaster200 manufactured by Tropel. First, the flatness before affixing a pellicle was measured about the mask 6025 quartz. Then, the pellicle which has the adhesive obtained in Example 1 was affixed to the said mask, and the flatness of the mask after pellicle adhesion was measured (measurement range: 135 mm x 110 mm). The flatness before and after adhesion was subtracted to calculate how much 6025 quartz was deformed by attaching the pellicle.

The pellicle was attached to quartz by a simple mounter (weighted: 15 Kgf, 60 sec).

(Double-circle): Deformation amount of a mask by attaching a pellicle is 25 nm or less

(Circle): The deformation amount of the mask by attaching a pellicle is more than 25 nm and 35 nm or less

(Triangle | delta): Deformation amount of the mask by attaching a pellicle more than 35 nm and 60 nm or less

X: Deformation amount of a mask by attaching a pellicle more than 60 nm

<Examples 2 to 9, Comparative Examples 1 and 2>

A pellicle was produced in the same manner as in Example 1, except that each component was mixed to obtain a mixture shown in Table 1 and a mixture was obtained. Evaluation similar to Example 1 was performed about the obtained pellicle. These results are also shown in Table 1.

Comparative Example 3

Block mass of 100 mass parts of styrene ethylene butylene styrene copolymers, 80 mass parts of hydrogenated terpene resins, 40 mass parts of paraffinic process oils, and 2 mass parts of antioxidant (BHT) are melt-mixed at 220 degreeC using a kneader. An adhesive was obtained. About 10 g of mask adhesive was poured into a heating tank (tank temperature: 200 ° C) to melt.

On the other hand, a pellicle frame made of anodized aluminum alloy (outer diameter 113 mm x 149 mm, inner diameter 109 mm x 145 mm, height 2.9 mm) was prepared. The mask adhesive of the molten state extruded from the needle tip connected to the heating tank was apply | coated on one end surface of the pellicle frame, and the mask adhesive layer was formed. The thickness of the formed mask adhesive layer was 0.6 mm. Then, the protective film made from polyester of 100 micrometers in thickness which carried out the silicone mold release process was bonded to the surface of a mask adhesive layer. A pellicle was produced by attaching a pellicle film to the other end surface of the pellicle frame through a film adhesive layer.

Peelability evaluation and deformation | transformation evaluation of the mask were performed similarly to Example 1 about the obtained pellicle. Each result is shown in Table 1.

<Comparative Example 4>

Ethyl acetate (30 parts by mass) was added to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube. A mixture in which isobutyl acrylate / butyl acrylate / acrylic acid / 2-hydroxyethyl acrylate / 2,2'-azobisisobutyronitrile was mixed at a mass ratio of 30/66 / 1.5 / 2.5 / 1 (32 parts by mass ) Was added to ethyl acetate and reacted at 60 ° C. for 8 hours under a nitrogen atmosphere. Toluene (38 mass parts) was added to the reaction solution after completion | finish of reaction, and the acrylic copolymer solution of 32 mass% of non volatile matter concentrations was obtained (weight average molecular weight 1.3 million). 0.3 weight part addition and stirring of polyfunctional epoxy compound (toluene solution of 1, 3-bis (N, N- diglycidyl aminomethyl) cyclohexane, 5% of non volatile matter concentration) to 100 mass parts of obtained acrylic copolymer solutions It mixed and obtained the adhesive precursor composition.

On the other hand, a pellicle frame made of anodized aluminum alloy (outer diameter 113 mm x 149 mm, inner diameter 109 mm x 145 mm, height 3.2 mm) was prepared. Here, four jig holes with a hole diameter of 1.6 mm and a depth of 1.2 mm were formed at positions 25 mm from the corner portions of the outer side of the pellicle frame at positions that became 1.7 mm from the film adhesive-coated end face as pin holes. . The combined said adhesive composition was apply | coated with the dispenser on one end surface of the pellicle frame. This was heat-dried and cured in 2 steps (1st step: 100 degreeC, 8 minutes, 2nd step: 180 degreeC, 8 minutes), and the mask adhesive layer was formed. Then, the protective film made from polyester of 100 micrometers in thickness which carried out the silicone mold release process on the surface of the mask adhesive layer was bonded, it was made to cure for 3 days at room temperature (20 +/- 3 degreeC), and the adhesive force was stabilized. The thickness of the formed mask adhesive layer was 0.3 mm. A pellicle was produced by attaching a pellicle film to the other end surface of the pellicle frame through a film adhesive layer.

Peelability evaluation and deformation | transformation evaluation of the mask were performed similarly to Example 1 about the obtained pellicle. Each result is shown in Table 1.

According to the present invention, it is possible to sufficiently prevent the residue of the adhesive on the mask after exposure. The present invention can be suitably used in lithography processes such as IC (integrated circuit), LSI (large scale integrated circuit), LCD (liquid crystal display), and is particularly lithography using an excimer laser used for exposure requiring high resolution. Process, Preferably it can be used suitably at the time of the lithographic process using the ultraviolet light exposure of 200 nm or less.

1: pellicle
2: pellicle frame
2e, 2f: end face of pellicle frame
3: pellicle film
10: adhesive
F: protective film

Claims (13)

Pellicle frame,
A pellicle film mounted on one end of the pellicle frame;
Non-cross-linked acrylic pressure-sensitive adhesive attached to the other end surface of the pellicle frame
And
The non-crosslinked acrylic pressure sensitive adhesive includes an acrylic base polymer (B) and an acrylic polymer (A) as a tackifier,
The pellicle whose content of the weight average molecular weight 800 or less compound in the said non-crosslinked acrylic adhesive is 15 mass% or less. The pellicle of Claim 1 whose elasticity modulus of the said non-crosslinking acrylic adhesive is 20 mN / mm <2> or more and 180 mN / mm <2> or less. The pellicle of Claim 1 or 2 whose glass transition temperature of the said non-crosslinked acrylic adhesive is less than -25 degreeC. delete The glass transition temperature of the said acrylic polymer (A) is -30 degrees C or less,
The pellicle whose glass transition temperature of the said acrylic base polymer (B) is -25 degreeC or more. The pellicle of Claim 1 or 2 whose content of the said acrylic polymer (A) in the said non-crosslinked acrylic adhesive is 15-80 mass%. The pellicle according to claim 1 or 2, wherein the acrylic polymer (A) is a polymer or copolymer of alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms. The pellicle according to claim 1 or 2, wherein the acrylic base polymer (B) is a block polymer. The method according to claim 8, wherein the block polymer has a structure represented by the following general formula (I) in the polymer backbone,
In formula (I), (a1) and (a2) represent a polymer with a glass transition temperature of 80 degrees C or more, respectively, (b) a pellicle which shows a polymer with a glass transition temperature of 30 degrees C or less.

(A1) and (a2) in the said general formula (I) contain the alkyl ester of methacrylic acid of C1-C14, respectively,
(B) in the said General formula (I) is a pellicle containing the C1-C14 alkyl (meth) acrylic-acid alkylester. The weight average molecular weight of the said acrylic polymer (A) is 850 or more and 70000 or less,
The pellicle whose weight average molecular weights of the said acrylic base polymer (B) are 10000 or more and 500000 or less. The photomask with a pellicle in which the pellicle of Claim 1 or 2 is mounted. The manufacturing method of the semiconductor element which comprises the process of exposing a board | substrate with the photomask with a pellicle of Claim 12.

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