TWI614324B - Film, protective film mask and semiconductor component manufacturing method - Google Patents

Description

Film, protective film mask and semiconductor component manufacturing method

The present invention relates to a method of preventing a foreign matter from adhering to a mask (photomask) when manufacturing a semiconductor device such as an LSI (Large Scale Integration) or a semiconductor device such as a super LSI or a liquid crystal display panel. ) The light lithography film.

In the photolithography step of semiconductor manufacturing, a semiconductor manufacturing apparatus such as a stepper (reduced projection exposure apparatus) is used to form a photoresist pattern corresponding to an integrated circuit on a wafer. The protective film is formed by arranging a transparent film on one end surface of the frame having the frame shape to prevent the foreign matter from directly adhering to the reticle to form a circuit pattern. Specifically, even if foreign matter adheres to the protective film in the photolithography step, the foreign matter is not imaged on the wafer coated with the photoresist. Thereby, it is possible to prevent short-circuiting and disconnection of the semiconductor integrated circuit due to defects in the circuit pattern caused by the image of the foreign matter, and it is possible to improve the manufacturing yield of the photolithography step.

In recent years, with the high integration of semiconductor devices, the short wavelength of light for exposure in the photolithography step has been increasing. That is, when it is required to draw an integrated circuit pattern on a wafer, it is possible to draw a fine circuit pattern with a narrower line width. In order to cope with this situation, for example, a KrF excimer laser (wavelength 248 nm), an ArF excimer laser (wavelength 193 nm), and an F ₂ standard are used from the previous g line (wavelength 436 nm), i line (wavelength 365 nm). Light having a shorter wavelength such as a molecular laser (wavelength 157 nm) is used as a light for exposure of a stepper for photolithography.

With the short-wavelength and high energy of the exposure light in recent years, the frequency of contamination of the film or the mask by exposure increases, and the frequency of replacement of the film and the mask also changes. high. Here, as a method of fixing the film to the photomask, a method in which the adhesive is detachably fixed by an adhesive is generally used. Acrylic, rubber, polybutene, polyurethane, and polyoxygen are known as adhesives (see Patent Document 1), and thermoplastic elastomers are known (see Patent Document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 05-281711

[Patent Document 2] International Gazette No. 2012-004951

It is desirable that the adhesive stably has an appropriate adhesive force, and when the protective film is replaced, the cohesive agent is prevented from being cohesively broken when the protective film is peeled off from the photomask, and the adhesive is partially attached to the photomask (hereinafter, This phenomenon is called paste residue). However, with the short-wavelength and high energy of the exposure light in recent years, the adhesive described in Patent Document 1 is easily combined with the photomask due to the decomposition of the adhesive due to light leakage, and the protective film is attached to the mask. When peeling off, the paste residue of the adhesive is liable to occur on the surface of the mask. Further, in the adhesive described in Patent Document 2, the acrylic pressure-sensitive adhesive also has a problem in preventing the residue from remaining in the paste. Especially when a short wavelength of 200 nm or less is used, contamination of a photomask called a haze is generated. Therefore, the frequency of replacement of the protective film becomes high, and therefore it is required that the adhesive does not remain on the photomask when peeling off from the photomask.

The present invention has been made in view of the above problems, and it is an object of the invention to provide a protective film, a mask for an adhesive film, and a method for producing a semiconductor element, which can sufficiently prevent the paste from remaining when the protective film is peeled off from the mask.

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

(1) A protective film comprising: a protective film frame; a film film body which is stretched on one end surface of the film frame; and a non-crosslinking type acrylic adhesive adhered to the other end surface of the film frame; and the weight average molecular weight of the adhesive is 800 or less The content of the compound is 18% by mass or less.

(2) The protective film of (1), wherein the non-crosslinked acrylic adhesive has an elastic modulus of ²⁰ mN/mm ² or more and 180 mN/mm ² or less.

(3) The film of (1) or (2), wherein the glass transition temperature of the non-crosslinked acrylic adhesive is less than -25 °C.

(4) The protective film of any one of (1) to (3), wherein the non-crosslinking type acrylic adhesive contains an acrylic polymer (A) and an acrylic base polymer (B).

(5) The film of (4), wherein the glass transition temperature of the acrylic polymer (A) is -30 ° C or lower, and the glass transition temperature of the acrylic base polymer (B) is -25 ° C or higher.

(6) The film of (4) or (5), wherein the content of the acrylic polymer (A) in the non-crosslinked acrylic adhesive is 15 to 80% by mass.

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

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

(9) The film of (8), wherein the block polymer has a structure represented by the following formula (I) in the polymer main chain, and in the formula (I), (a1) and (a2) respectively represent (a) a polymer having a glass transition temperature of 80 ° C or higher, and (b) a polymer having a glass transition temperature of 30 ° C or lower, -(a1)-(b)-(a2)-(I).

(10) The film of (9), wherein (a1) and (a2) in the formula (I) mainly contain carbon number 1 The alkyl methacrylate of ~14, (b) in the formula (I) mainly contains an alkyl (meth) acrylate having a carbon number of 1 to 14.

(11) The film of any one of (4) to (10), wherein the weight average molecular weight of the acrylic polymer (A) is 850 or more and 70,000 or less, and the weight average molecular weight of the acrylic base polymer (B) It is 10,000 or more and 500,000 or less.

(12) A mask for an attachment film, which is provided with a protective film according to any one of (1) to (11).

(13) A method of manufacturing a semiconductor device, comprising the steps of: exposing a substrate by using a photomask of the protective film of (12).

According to the present invention, the residue of the paste when the film is peeled off from the photomask can be sufficiently prevented.

1‧‧‧ film

2‧‧‧Shield casing

2e, 2f‧‧‧ end face of the casing

3‧‧‧Shield film body

10‧‧‧Adhesive

20‧‧‧Photomask

20p‧‧‧ pattern

20f‧‧‧ end face

30‧‧‧Photomask with protective film

40‧‧‧Exposure light

50‧‧‧Optical system

60‧‧‧Substrate

62‧‧‧ photoresist

F‧‧‧Protective film

Fig. 1 is a perspective view showing a protective film according to an embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

Fig. 3 is a view schematically showing a step of exposing a substrate by using a mask of an envelope film according to an embodiment of the present invention.

Hereinafter, the form for carrying out the present invention (hereinafter, simply referred to as "this embodiment") will be described in detail. The following examples are intended to illustrate the invention and are not intended to limit the invention to the following. The present invention can be carried out with appropriate changes within the scope of the gist of the invention.

Fig. 1 is a perspective view showing a protective film of the embodiment, and Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1. As shown in FIG. 1 and FIG. 2, the protective film 1 includes: a protective film frame 2; a protective film body 3 which is stretched over one end surface 2e of the protective film frame 2; and an adhesive 10 attached to the protective film frame The other end face 2f of the body 2; and the protective film F adhere to the adhesive 10 to protect the adhesive 10. 3 is a view schematically showing a step of exposing a substrate by using a mask of the protective film of the embodiment; Figure. As shown in FIG. 3, the mask 30 of the protective film of this embodiment includes the film 1 and the mask 20. The other end surface 2f of the film 1 is attached to the end surface 20f of the mask 20 on the side where the pattern 20P is formed via the adhesive 10. In order to expose the substrate 60, the mask 30 of the protective film is irradiated with the exposed light 40 from above the mask 30 of the protective film. The exposed light 40 passes through the photomask 30 of the protective film, is condensed by, for example, the light projecting optical system 50, and is irradiated onto the substrate 60 on the surface of which the photoresist 62 is provided. Thereafter, the pattern 20P of the photomask 20 is transferred onto the surface of the substrate 60 by a specific step such as a development step or an etching step. Substrate 60 includes, for example, a semiconductor material. The step of transferring the pattern 20P of the reticle 20 to the surface of the substrate 60 using the reticle 30 of the protective film as described above is, for example, part of the manufacturing steps of the semiconductor element.

(adhesive)

The adhesive (acrylic adhesive) used for the film of the present embodiment is a non-crosslinking type acrylic adhesive, and the content ratio of the compound having a weight average molecular weight of 800 or less in the acrylic adhesive is 18% by mass or less. . The non-crosslinking type referred to herein also includes a case where a reaction product with a hardening material is contained within a range in which the effects of the present invention are exerted.

Further, the glass transition temperature of the acrylic pressure-sensitive adhesive of the present embodiment is preferably less than -25 ° C, more preferably -27 ° C or less, still more preferably -30 ° 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 the range. When the glass transition temperature is within the above range, the adhesive having a low modulus of elasticity and being soft is used, so that the effect of reducing the deformation of the mask described below can be more effectively exhibited. In addition, the lower limit of the glass transition temperature of the acrylic pressure-sensitive adhesive of the present embodiment is not particularly limited, but is preferably -90 ° C or more from the viewpoint of ease of handling or moldability of the mask adhesive.

Moreover, the elastic modulus of the acrylic pressure-sensitive adhesive of the present embodiment is preferably ²⁰ mN/mm ² or more and 180 mN/mm ² or less. When the modulus of elasticity is within the above range, the film can be prevented from shifting from the mask while maintaining the softness, and the adhesion applied to the mask can be alleviated, thereby reducing the deformation of the mask applied to the mask. . Elastic modulus aspect of this embodiment of the acrylic adhesive agent is more preferably 30mN / mm ² or more and 160mN / mm ² or less, and preferably 40mN / mm ² or more and 140mN / mm ² or less. The modulus of elasticity of the adhesive can be adjusted in consideration of the modulus of elasticity of the base polymer used in the adhesive and the compatibility in the case of using a plurality of base polymers.

Further, the acrylic adhesive used in the protective film of the present embodiment preferably contains an acrylic polymer (A) and an acrylic base polymer (B) from the viewpoint of imparting excellent elastic adhesion. Here, the weight average molecular weight of the above compound or the like is a value measured by GPC (Gel Permeation Chromatograph).

(a compound having a weight average molecular weight of 800 or less)

A compound having a weight average molecular weight of 800 or less is used as an adhesion-imparting agent for exhibiting adhesion of a non-crosslinked acrylic adhesive or improving adhesion and adhesion properties. The adhesion-imparting agent not only requires good compatibility with the polymer (base polymer) which is the basis of the adhesive, but also imparts excellent viscous flow characteristics to the adhesive, that is, the immediate bonding property at the deformation or deformation speed of the adhesive. It is therefore important that the molecular weight is substantially lower than the base polymer. Therefore, a low molecular weight compound having a weight average molecular weight of 800 or less is usually used as an adhesion-imparting agent.

As described above, the content ratio of the compound having a weight average molecular weight of 800 or less in the adhesive is 18% by 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 above compound is appropriately prevented from oozing out to the surface of the adhesive. Thereby, cohesive failure of the adhesive can be suppressed, and the residue of the paste can be reduced. The content ratio of the above compound is preferably as small as possible, and more preferably 15% by mass or less, 10% by mass or less, 7% by mass or less, or 3% by mass or less. The compound may not be contained in the adhesive, and when the compound is contained in the adhesive, the content of the compound may be 0.5% by mass or more or 1% by mass or more.

Furthermore, the previous acrylic adhesives are roughly classified into crosslinked and non-crosslinked adhesives. Attention. Usually, in the case of a non-crosslinked acrylic adhesive, a base polymer and an adhesion-imparting agent are contained. The adhesive agent is a compound containing a rosin-based resin, a terpene-based resin, a petroleum-based resin, or the like, and having a molecular weight of several hundreds to several thousands and being amorphous. The adhesion-imparting agent which is most widely used for an acrylic adhesive is a rosin-based resin. Since the rosin-based resin has a three-dimensional and bulky ring structure, it has a low molecular weight and a narrow molecular weight distribution as compared with other petroleum-based resins exhibiting the same softening point. Further, since the rosin-based resin has a polar group such as an ester bond and is excellent in compatibility with a base polymer, it is applied at most as an adhesion-imparting agent for an acrylic pressure-sensitive adhesive. However, since the rosin-based resin contains a structure having an unsaturated bond of a substitute rosin acid, it is easily oxidized, and the light resistance and the like are inferior. Therefore, a resin obtained by esterifying a hydrogenated or polymerized modified rosin or a rosin derivative excellent in optical use such as an ultra-light coloring technique has been developed.

In the conventional acrylic pressure-sensitive adhesive, the adhesion-imparting agent is prepared in an amount of 20% by mass or more and 80% by mass or less in the base polymer in order to make the base polymer and the adhesion-imparting agent compatible to exhibit adhesiveness and rubber elasticity. The reason for this is that the adhesion is generally insufficient when the adhesion-imparting agent is less than 20% by mass. However, when the adhesion-imparting agent is set to the above-described content ratio, separation or the like occurs between the adhesion-imparting agent and the base polymer. Therefore, the adhesion-imparting agent oozes to the surface, and the adhesion-imparting agent moves to the side of the mask to remain on the side of the mask. It is considered to be one of the causes of the occurrence of paste residue when the prior acrylic adhesive is used.

(acrylic polymer (A))

The glass transition temperature of the acrylic polymer (A) is -30 ° C or lower, preferably -33 ° C or lower, more preferably -35 ° C or lower. By setting the glass transition temperature of the acrylic polymer (A) to -30 ° C or lower, it has good elastic adhesion even when the ambient temperature is low, and the workability is also good. The lower limit is not particularly limited, but the glass transition temperature is preferably -90 ° C or higher in terms of ease of handling and ease of acquisition. Further, when the acrylic polymer (A) has a plurality of glass transition temperatures, as long as the complex It is sufficient that at least one of the plurality of glass transition temperatures is within the above range, and it is preferred that all of the plurality of glass transition temperatures are within the above range. Further, the glass transition temperature used for the compound or the like of the present embodiment is a value obtained by DSC (Differential Scanning Calorimetry).

When the glass transition temperature is in the above range, the acrylic polymer (A) becomes a liquid at normal temperature, so that it is easy to handle. In addition, by using the acrylic polymer (A), it is possible to exhibit an adhesive force which can be used as an adhesive for a protective film, without disposing a conventional adhesive agent such as a rosin-based resin in an acrylic adhesive. The reason for this is that the compatibility with the monomer component having the adhesiveness and flexibility contained in the acrylic base polymer (B) is improved by using the acrylic polymer (A). Further, since the acrylic polymer (A) has good compatibility with the acrylic base polymer (B), it is not easily phase-separated and has good light resistance. Therefore, the ratio of exudation to the surface as in the conventional adhesion-imparting agent becomes small. The paste residue of the adhesive is suppressed.

In addition, with the short-wavelength and high energy of the recent exposure light, the miniaturization of the pattern has been progressing. As a method of miniaturization, double patterning is known, and it is usually exposed twice using two masks. Therefore, it is important to improve the positional accuracy of the two patterns formed. That is, 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. Therefore, it is necessary to reduce the positional deviation of the two patterns formed, so that the flatness required for the mask is necessary. At this time, if the protective film is attached to the photomask, the mask may be deformed.

As one of the causes of the deformation of the mask, it is considered that when the film is pressure-bonded to the mask via the adhesive, the deformation of the film frame is transmitted by the adhesive. Therefore, in order to prevent the deformation of the film casing from being transmitted to the reticle, it is considered that the deformation energy of the film casing is moderated by softening the adhesive, and as a result, the reticle deformation is reduced. When the glass transition point of the acrylic polymer (A) is within the above range, the compatibility with the acrylic base polymer (B) is good, and flexibility can be exhibited. Thereby, the above-described mask deformation can be reduced.

The content of the acrylic polymer (A) is preferably from 15 to 80% by mass based on the total amount of the adhesive. More preferably, it is 18 to 75 mass%, further preferably 20 to 70 mass%, particularly preferably 30 to 70 mass%, and more preferably 40 to 70 mass%. When the content is 15% by mass or more, an appropriate adhesive force can be obtained, and when the content is 80% by mass or less, the cohesive force can be set to an appropriate range, and the holding power can be improved. By setting the content of the acrylic polymer (A) to the above range, it is possible to prevent the protective film from being dropped from the mask after the film is attached to the mask.

The acrylic polymer (A) is preferably an alkyl (meth) acrylate polymer or copolymer having an alkyl group having 1 to 14 carbon atoms, from the viewpoint of functioning as a softening agent. Things. The polymer or copolymer may also contain a diblock or a triblock, and one or two or more kinds of alkyl (meth)acrylate monomers may be polymerized or one or more of them ( It is obtained by polymerizing a mixture of a methyl methacrylate monomer and a monomer other than the alkyl (meth) acrylate monomer. In addition, one or two or more of these polymers or copolymers may be used depending on the functionality to obtain the acrylic polymer (A). In addition, "(meth)acrylic" in this specification means "acrylic acid" and the corresponding "methacrylic acid".

Specific examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. , hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobutyl (meth) acrylate, (methyl) Isooctyl acrylate, cyclohexyl (meth)acrylate, (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, methoxy acrylate A (meth) acrylate of a linear aliphatic alcohol such as a ethyl ester or a (meth) acrylate having a branched alkyl chain. Further, as the other monomer, a monomer copolymerizable with an alkyl (meth)acrylate monomer, for example, acrylic acid, vinyl acetate, styrene or the like can be used.

Among them, butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (methyl) A polymer or copolymer of an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms such as 2-methoxyethyl acrylate or isobutyl (meth)acrylate is apt to have an acrylic base polymerization. The substance (B) is preferred because it exhibits the compatibility of the monomer component of the adhesiveness. Further, the above polymer or copolymer may also function as a softening agent.

The molecular weight of the acrylic polymer (A) is preferably 850 or more and 70,000 or less, more preferably 900 or more and 68,000 or less, by weight average molecular weight. When the weight average molecular weight of the acrylic polymer (A) is 850 or more, sufficient adhesive strength can be obtained, and if it is 70,000 or less, the viscosity can be controlled to an appropriate range, and the workability is improved. good.

Moreover, by making the weight average molecular weight 850 or more and 70,000 or less, it is easy to be compatible with the acrylic base polymer (B). Therefore, the adhesiveness of the acrylic base polymer (B) can be improved, and the acrylic polymer (A) can also function as an adhesion-imparting agent. Further, even when the compound having a molecular weight of 800 or less is used in an amount of 18% by mass or less, the adhesive force of the adhesive can be favorably exhibited, and the residue of the paste can be improved.

The average molecular weight of the acrylic polymer (A) is preferably in the range of 1.0 to 2.0 in terms of M _W /M _N from the viewpoint of preventing the residue of the paste. Further, a block polymer can be preferably used because the adhesive is applied to the sheath frame in a thick manner and the mask of the mask when the film is attached to the mask can be reduced.

Specific examples of the acrylic polymer (A) include the product name "ARUFON (registered trademark)" series (manufactured by Toagosei Co., Ltd.) and the product name "Kurarity (registered trademark)" series (manufactured by Kuraray Co., Ltd.) )Wait. The product name "ARUFON (registered trademark)" series has less impurities because it does not use a polymerization initiator, a chain transfer agent, a solvent, etc., and if the M _W /M _N is 1.0 to 2.0, the molecular weight distribution is narrow, so the anti-paste is anti-paste. The residue of the agent is particularly excellent. Further, since the product name "Kurarity (registered trademark)" series is a triblock copolymer having a hard segment and a soft segment, it can be applied to the film casing in a thick manner, and therefore the reduction in the deformation of the mask is particularly excellent. Further, when the M _W /M _N of the product name "Kurarity (registered trademark)" is 1.0 to 2.0, the molecular weight distribution is narrow, and therefore the anti-paste residual property is also excellent.

(Acrylic base polymer (B))

In the present embodiment, the glass transition temperature of the acrylic base polymer (B) is preferably -25 ° C or more and 140 ° C or less. It is particularly preferably -25 ° C or more and 130 ° C or less, more preferably -25 ° C or more and 120 ° C or less. 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 the range. Further, in the acrylic base polymer (B), the adhesive can be applied to the sheath frame in a thick manner, and the mask can be reduced in the case where the mask is attached to the mask. It is a block polymer.

The glass transition temperature of the above block polymer is preferably -25 ° C or higher, and preferably 140 ° C or lower. It is particularly preferably -10 ° C or more and 130 ° C or less, and further preferably 0 ° C or more and 120 ° C or less.

The above block polymer comprises the general formula (I)-(a1)-(b)-(a2)-. The glass transition temperature of (a1) and (a2) of the formula (I) is preferably 80 ° C or higher. The glass transition temperature of (b) of the formula (I) is preferably 30 ° C or lower. Further, (b) of the formula (I) is preferably a block polymer having a polymer having a glass transition temperature of 30 ° C or less in the main chain.

The polymer component of the polymer block represented by (a1) and (a2) of the formula (I) (hereinafter, the polymer block is referred to as "polymer block a") is a polymer. From the viewpoint that the glass transition temperature of the block a is 80 ° C or higher, it is preferably an alkyl methacrylate having a carbon number of 1 to 14. Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and methacrylic acid. Butyl ester, second butyl methacrylate, third butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, methyl Pentadecyl acrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, methyl propyl One type or two or more types of 2-hexyl decyl acrylate. Among them, from the viewpoint of setting the glass transition temperature of the polymer block a to 80 ° C or higher, it is more preferable to use methyl methacrylate, ethyl methacrylate, n-propyl methacrylate or methacrylic acid. An ester containing methacrylic acid and an alcohol having 3 or less carbon atoms as a main component such as propyl ester. Here, "mainly" means at least half of the entire polymer block a, and preferably 80% or more is occupied by an alkyl methacrylate having 1 to 14 carbon atoms. Further, at least one of the polymer blocks a may contain an alkyl methacrylate having 1 to 14 carbon atoms.

In the polymer block a of the formula (I), if it is a small ratio (for example, less than half, preferably less than 20%), it may also comprise a constituent component derived from, for example, a monomer such as: a methacrylate other than an alkyl ester such as trimethyl decyl acrylate, trimethoxy decyl propyl methacrylate, glycidyl methacrylate or allyl methacrylate; methyl acrylate or acrylic acid An alkyl acrylate such as butyl ester or tributyl acrylate; an olefin such as ethylene or propylene; and a lactone such as ε-caprolactone or valerolactone. When the glass transition temperature of the polymer block a is 80 ° C or more, it is preferable to sufficiently obtain the holding power and the cohesive force at a high temperature.

The glass transition temperature of the polymer block b is set to the monomer component of the polymer block (hereinafter referred to as "polymer block b") represented by the formula (I) (b). From the viewpoint of 30 ° C or lower, it is preferably an alkyl acrylate and/or an alkyl methacrylate having a carbon number of 1 to 14. Examples of the alkyl acrylate which can constitute the polymer block b include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylic acid second. One or more of ester, butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate. Further, examples of the alkyl methacrylate monomer which can constitute the polymer block b include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate. N-butyl methacrylate, isobutyl methacrylate, second butyl methacrylate, third butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, A 2-ethylhexyl acrylate One or two or more kinds of esters, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, and 2-hexyl decyl methacrylate. In the case where the alkyl methacrylate is used as the main monomer component to form the polymer block b, the glass transition temperature is 30 ° C or lower, preferably n-butyl methacrylate. , isobutyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, lauric acid methacrylate An ester of methacrylic acid such as ester, tridecyl methacrylate or 2-hexyl decyl methacrylate with an alcohol having 4 or more carbon atoms is mainly used. In the polymer block b, other constituent components may be included in a range that does not adversely affect the paste residue and the light resistance on the photomask.

By setting the glass transition temperature of the polymer block b to 30 ° C or lower, the adhesion and the holding power are sufficiently obtained, which is preferable.

The above block polymer has a structure in which one polymer block b is located between two polymer blocks a like (a1) and (a2) of the formula (I). However, if the above three polymer blocks are contained in a specific order, not only the block copolymer composed of only the three polymer blocks but also one or more other polymers may be contained. A block copolymer composed of four or more polymer blocks of the segment. The above other polymer blocks may be the same polymer block as the polymer block a or b, or may be a polymer block c of a different kind. Examples of the polymer block c of a different type include polymer blocks such as an olefin such as ethylene or propylene, and a lactone such as ε-caprolactone or valerolactone.

Preferred examples of the block copolymer in the present embodiment include a polymer block a-polymer block b-polymer block a, and a polymer block a-polymer block b-polymer block a. - polymer block b, polymer block a - polymer block b - polymer block a - polymer block c and the like.

The molecular weight of the block copolymer is preferably in the range of 10,000 to 500,000, more preferably in the range of 30,000 to 450,000, and still more preferably in the range of 50,000 to 400,000, in terms of weight average molecular weight. By making the weight average molecular weight of the block copolymer in the range of 10,000 to 500,000, polymerization can be carried out by a living polymerization method or the like to obtain a block copolymer having a narrow molecular weight distribution and a small amount of impurities. Thereby, it is preferable to improve the paste residue of the adhesive, and to apply the adhesive thicker. Further, from the above viewpoints, as the molecular weight distribution, M _W /M _N is preferably 1.0 to 2.0.

Further, in the block copolymer, the ratio (a/b) of the total mass of the polymer block a based on the total mass of the polymer block b contained in the molecule is preferably 5/95 to 80/ 20. Further, a/b is more preferably 10/90 to 75/25. By setting a/b to 5/95 or more, the cohesive force of the adhesive is sufficiently obtained, and a high holding force tends to be obtained. Further, by setting a/b to 80/20 or less, the adhesive strength is sufficiently obtained.

In the case of the above block copolymer, a side chain having a branched structure having a large volume can be formed in the polymer. Therefore, the adhesive can be applied thickly, and the deformation of the mask when the film is attached to the mask can be reduced. Further, since the acrylic polymer (A) is particularly excellent in compatibility with the polymer block b, the adhesion and flexibility can be improved, and the mask deformation can be reduced.

Further, in the block copolymer, it is possible to prevent the paste on the mask from remaining and to adversely affect the light resistance of the acrylic base polymer (B) in the molecular side chain or at the end of the molecular main chain. It has a functional group such as a hydroxyl group, a carboxyl group, an acid anhydride group or an amine group.

Specific examples of such a block copolymer include a product name "Kurarity (registered trademark)" series (manufactured by Kuraray Co., Ltd.), a product name "Nanostrength" series (manufactured by Arkema Co., Ltd.), and the like.

In addition to the acrylic polymer (A) and the acrylic base polymer (B), an inorganic substance may be added to improve light resistance or to improve paste residue.

The protective film of the present embodiment can be preferably produced, for example, by the following method.

First, the acrylic polymer (A) and the acrylic base polymer (B) are mixed to obtain an adhesive composition. In this case, in order to attach (coat) the adhesive 10 to The end face of the film frame 2 is used as a mask adhesive layer of a specific thickness and width, and the adhesive composition is further diluted with a solvent to adjust the solution concentration (viscosity). The thickness of the mask adhesive layer is preferably 0.25 mm or more and 3.0 mm or less. In the case of semiconductors, 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 the case of liquid crystal, 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. Further, the width of the mask adhesive layer is preferably 30% or more and 90% or less, more preferably 40% or more and 80% or less of the width of the applied frame. The frame width is usually 1.0 mm or more and 20 mm or less.

Second, the adhesive composition is applied to the other end surface 2f of the protective film casing 2 having the protective film body 3 stretched over the one end surface 2e. The coating method is not particularly limited. However, when the adhesive composition is diluted with a solvent, it is preferably applied by using a dispenser or a syringe. Further, a hot melt method in which the adhesive composition is thermally melted and applied can also be used.

Third, in the case where the adhesive composition is diluted with a solvent, the adhesive 10 molded by heat-drying the applied adhesive composition is adhered to the other end surface 2f of the protective cover 2 . When the adhesive composition is applied by a hot melt method, the adhesive 10 obtained by molding the applied adhesive composition and then cooled is adhered to the other end surface 2f of the protective cover 2 . The protective film F for protecting the adhesive side of the adhesive 10 may be attached after the adhesive composition is dried or cooled. As the protective film F, for example, a film made of polyester having a thickness of 30 to 200 μm or the like is used. Further, when the peeling force is large when the protective film F is peeled off from the adhesive 10, the adhesive 10 is deformed at the time of peeling. Therefore, the surface of the protective film F that is in contact with the adhesive 10 may be subjected to a release treatment using polyfluorene or fluorine or the like in advance to obtain a suitable peeling force.

After the protective film F for protecting the adhesive surface of the adhesive 10 is attached, a load is applied to form the surface of the adhesive to be substantially flat.

[Examples]

Hereinafter, the present embodiment will be specifically described by way of examples and comparative examples, but The embodiment is not limited by these.

The acrylic polymer (A), the acrylic base polymer (B), and the compound having a molecular weight of 800 or less are used as follows. In addition, the acrylic polymer (A) is represented by a ratio of a molecular weight of 800 or less which is obtained by GPC measurement.

(acrylic polymer (A))

‧ARUFON (registered trademark) UP1190 (manufactured by Toagosei Co., Ltd.) (28.2%)

(glass transition temperature: -50 ° C)

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

(glass transition temperature: -61 ° C)

‧ARUFON (registered trademark) UP1000 (manufactured by Toagosei Co., Ltd.) (13.7%)

(glass transition temperature: -77 ° C)

‧Kurarity (registered trademark) LA1114 (manufactured by Kuraray Co., Ltd.) (0.0%)

(glass transition temperature: -40 ° C)

‧i-BA/BA/AA/HEA (Isobutyl acrylate/butyl acrylate/acrylic acid/2-hydroxyethyl acrylate) (2.4%)

(glass transition temperature: -51 ° C)

(Acrylic base polymer (B))

‧Kurarity (registered trademark) LA2140e (manufactured by Kuraray Co., Ltd.)

(glass transition temperature: -38 ° C, 85 ° C)

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

(glass transition temperature: -39 ° C, 86 ° C)

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

(glass transition temperature: -54 ° C, 100 ° C)

(compounds with a molecular weight of 800 or less)

‧Pine Crystal (registered trademark) KE-311 (made by Arakawa Chemical Industries Co., Ltd.)

The measurement of the molecular weight of the acrylic polymer (A), the acrylic base polymer (B), the glass transition temperature, and the content of each copolymer component, and the adhesion of the acrylic polymer (A) and the acrylic base polymer (B) The glass transition temperature and modulus of elasticity of the agent are carried out according to the apparatus and conditions described below.

(1) Determination of molecular weight by GPC (gel permeation chromatography)

‧Installation: Gel Permeation Chromatograph (HLC-8320) manufactured by Tosoh Co., Ltd.

‧Tube: "TSKgel SUPER HZ3000×2" and "HZ2000×2" manufactured by Tosoh Co., Ltd. are connected in series

‧Eluent: Tetrahydrofuran

‧ Eluent flow rate: 0.6ml/min

‧column temperature: 40 ° C

‧Detector: differential refractive index (RI) meter

‧ Calibration curve: made with standard polystyrene

(2) Determination of glass transition temperature by DSC (differential scanning calorimetry)

‧Device: DSCQ2000 manufactured by TA Instruments

‧ Sealing plate

‧ Temperature range: -80 ° C ~ 160 ° C

‧ Heating rate: 5 ° C / min

‧ sample weight: 10mg

In the case where a plurality of glass transition temperatures of the adhesive containing the acrylic polymer (A) and the acrylic base polymer (B) are measured, the temperature on the lowest temperature side is shown in Table 1 as the glass transition temperature Tg.

(3) Determination of the content of each copolymerized component by proton nuclear magnetic resonance ( ¹ H-NMR) spectrometry

‧Device: Nuclear Magnetic Resonance Device (JNM-LA400) manufactured by JEOL Ltd.

‧ Solvent: Deuterated chloroform

Further, in the ¹ H-NMR spectrum, the signals in the vicinity of 3.6 ppm and 4.0 ppm belong to the ester group of the methyl methacrylate unit (-O-CH ₃ ) and the ester group of the n-butyl acrylate unit (-O-, respectively). Since CH ₂ -CH ₂ -CH ₂ -CH ₃ ), the content of the copolymerization component is determined by the ratio of the integral values of the signals.

(4) Determination of elastic modulus

One of the protective film with the protective film is cut, and then the protective film is gradually peeled off so that the adhesive layer is not deformed, and the mask adhesive layer is gradually peeled off from the protective film frame. At this time, when it is difficult to peel off, the baby talcum powder (Siccarol) is gradually peeled off from the hand and the adhesive layer, and the elongation of the peeled adhesive layer is 5% or less.

The peeled adhesive layer was measured at room temperature (25 ° C) using the apparatus described below.

Device name: Autograph (SHIMAZU EZ-S, manufactured by Shimadzu Corporation)

Load cell: 1N (clip chuck)

Chuck spacing: 40mm

Crosshead speed: 100mm/min

Using the above apparatus, the adhesive layer was stretched to an elongation of 20%. Further, the cross-sectional area of the adhesive layer was measured, and the measurement result was divided by the cross-sectional area, thereby obtaining a stress value per unit area.

A graph is prepared which includes an elongation value of the x-axis and a stress value per unit area of the y-axis, and draws a straight line at an elongation of 0% and an elongation of 20%, and the value of the y-axis at an elongation of 100% in this case Set to the elastic modulus.

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

The i-BA/BA/AA/HEA composition was adjusted by a known method. Specifically, the reaction capacity is provided to a mixer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube. Ethyl acetate (30 parts by weight) was added to the solvent, and isobutyl acrylate/butyl acrylate/acrylic acid/2-hydroxyethyl acrylate/2,2'- was added in a weight ratio of 48/48/1.5/2.5/1.0. A mixture of azobisisobutyronitrile (32 parts by weight) was reacted at 60 ° C for 8 hours under a nitrogen atmosphere. After completion of the reaction, toluene (38 parts by weight) was added to obtain an acrylic copolymer solution having a nonvolatile concentration of 32% by weight.

<Example 1> (production of film)

70 parts by mass of "Kurarity LA1114 (manufactured by Kuraray Co., Ltd.)" as the acrylic polymer (A) and an acrylic block copolymer "Kurarity LA2140e" (Kuraray Co., Ltd.) as a base-based acrylic polymer (B) 30 parts by mass were mixed in such a manner as to be 48 g as a whole, and a raw material mixture was obtained. The obtained raw material mixture was placed in a Labo Plastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd., content: 60 mL), and then sealed. The mixture was kneaded at 200 ° C and 100 rpm for 20 minutes to obtain a block-shaped reticle adhesive. About 10 g of the mask adhesive was placed in a heating bath (in-tank temperature: 200 ° C) to be melted.

、深度1.2mm之夾具孔。將自連通於加熱槽之針尖擠出之熔融狀態之光罩黏著劑塗佈於護膜框體之一端面上，而形成光罩黏著劑層。所形成之光罩黏著劑層之厚度為0.6mm。其後，於光罩黏著劑層之表面貼合經聚矽氧脫模處理之厚度100μm之聚酯製保護膜。於上述護膜框體之另一端面經由膜接著劑層而貼附護膜膜體，從而製作護膜。 On the other hand, a protective film frame made of an anodized aluminum alloy (outer diameter: 113 mm × 149 mm, inner diameter: 109 mm × 145 mm, height: 2.9 mm) was prepared. Here, as the pin hole, at a position of 1.7 mm from the end face of the film adhesive application, at a position of 25 mm from the corner of the outer side of the outer side of the film frame, four holes of 1.6 mm are provided.

, 1.2mm depth of the fixture hole. A mask adhesive which is extruded from a needle tip which is connected to the heating bath is applied to one end surface of the sheath frame to form a mask adhesive layer. The thickness of the formed mask adhesive layer was 0.6 mm. Thereafter, a polyester protective film having a thickness of 100 μm which was subjected to polysilicon oxide release treatment was attached to the surface of the mask adhesive layer. A protective film is attached to the other end surface of the above-mentioned protective film frame via a film adhesive layer to form a protective film.

The peeling evaluation and the deformation evaluation of the mask were performed about the obtained film. Each result is shown in Table 1.

(peelability evaluation)

With respect to the protective film of the adhesive obtained in Example 1, the protective film was peeled off, and a 6025 chrome-mask blank substrate was attached (30 Kgf, 60 sec) by a simple mounter to obtain a film attached thereto. Photomask substrate. After the photomask substrate was allowed to stand at room temperature (20±3° C.) for 2 hours, the photomask substrate was horizontally fixed, and each of the long sides of the protective film was grasped by a tensile tester. The four pin holes were pulled at a speed of 5 mm/min at the same time with respect to the mask surface at the same time, and the film was peeled off. The peeling property was observed on the surface of each adherend, and evaluated based on the following criteria. The paste residue in the present embodiment means a state in which a part of the adhesive adheres to the photomask due to cohesive failure.

◎: The residual area of the paste is 0% or more and 5% or less of the entire attached area.

○: The residual area of the paste exceeds 5% of the entire attached area and is 10% or less.

△: The residual area of the paste exceeds 10% of the entire attached area and is 20% or less.

×: The residual area of the paste exceeds 20% of the entire attached area and is 100% or less.

(Deformation evaluation of the mask)

The evaluation of the deformation caused by the deformation of the reticle or the like was carried out using a FlatMaster 200 manufactured by Tropel. First, for the photomask (6025 quartz), the flatness before attaching the protective film was measured. Then, the film of the adhesive agent obtained in Example 1 was attached to the mask, and the flatness of the mask after the film was attached (measurement range: 135 mm × 110 mm) was measured. By subtracting the flatness before and after the attachment, it is calculated how much the 6025 quartz is deformed by the attachment of the protective film.

The attachment of the film to the quartz is carried out using a simple placement machine (load: 15 Kgf, 60 sec).

◎: The amount of deformation of the mask caused by attaching the protective film is 25 nm or less.

○: The amount of deformation of the mask caused by attaching the protective film exceeds 25 nm and is 35 nm or less.

△: The amount of deformation of the mask caused by attaching the protective film exceeds 35 nm and is 60 nm or less.

×: The deformation of the reticle caused by attaching the protective film exceeds 60 nm

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

A film was prepared in the same manner as in Example 1 except that the components were mixed to obtain a mixture as shown in Table 1. The same evaluation as in Example 1 was carried out on the obtained film. These results are also shown in Table 1.

<Comparative Example 3>

100 parts by mass of a styrene-ethylene-butylene-styrene copolymer, 80 parts by mass of a hydrogenated terpene resin, 40 parts by mass of a paraffin-based processing oil, and 2 parts by mass of an antioxidant (BHT) at 220 ° C using a kneader Melt mixing is carried out to obtain a block-shaped reticle adhesive. About 10 g of the mask adhesive was placed in a heating bath (in-tank temperature: 200 ° C) to be melted.

On the other hand, a protective film frame made of an anodized aluminum alloy (outer diameter: 113 mm × 149 mm, inner diameter: 109 mm × 145 mm, height: 2.9 mm) was prepared. A mask adhesive which is extruded from a needle tip which is connected to the heating bath is applied to one end surface of the sheath frame to form a mask adhesive layer. The thickness of the formed mask adhesive layer was 0.6 mm. Thereafter, a polyester protective film having a thickness of 100 μm which was subjected to polysilicon oxide release treatment was attached to the surface of the mask adhesive layer. A protective film is attached to the other end surface of the above-mentioned protective film frame via a film adhesive layer to form a protective film.

With respect to the obtained film, the peeling evaluation and the deformation evaluation of the mask were performed in the same manner as in Example 1. Each result is shown in Table 1.

<Comparative Example 4>

Ethyl acetate (30 parts by mass) was placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. A mixture of isobutyl acrylate/butyl acrylate/acrylic acid/2-hydroxyethyl acrylate/2,2'-azobisisobutyronitrile in a mass ratio of 30/66/1.5/2.5/1 (32) The mass parts were added to ethyl acetate, and the mixture was reacted at 60 ° C for 8 hours under a nitrogen atmosphere. After the reaction was completed, toluene (38 parts by mass) was added to the reaction solution. In the solution, an acrylic copolymer solution (weight average molecular weight: 1.3 million) having a nonvolatile content of 32% by mass was obtained. To 100 parts by mass of the obtained acrylic copolymer solution, a toluene solution of a polyfunctional epoxy compound (1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) is added, and no volatile matter is added. The concentration of 5%) 0.3 parts by weight was stirred and mixed to obtain an adhesive precursor composition.

、深度1.2mm之夾具孔。利用分注器將所調製之上述黏著劑組合物塗佈於護膜框體之一端面上。將其以兩個階段進行加熱乾燥、固化(第1階段：100℃、8分鐘，第2階段：180℃、8分鐘)，而形成光罩黏著劑層。其後，於光罩黏著劑層之表面貼合經聚矽氧脫模處理之厚度100μm之聚酯製保護膜，於室溫(20±3℃)下熟化3天，使黏著力穩定化。所形成之光罩黏著劑層之厚度為0.3mm。於上述護膜框體之另一端面經由膜接著劑層而貼附護膜膜體，從而製作護膜。 On the other hand, a protective film frame made of an anodized aluminum alloy (outer diameter: 113 mm × 149 mm, inner diameter: 109 mm × 145 mm, height: 3.2 mm) was prepared. Here, as the pin hole, at a position of 1.7 mm from the end face of the film adhesive application, at a position of 25 mm from the corner of the outer side of the outer side of the film frame, four holes of 1.6 mm are provided.

, 1.2mm depth of the fixture hole. The prepared adhesive composition is applied to one end surface of the sheathing frame by a dispenser. This was heat-dried and solidified in two stages (first stage: 100 ° C, 8 minutes, second stage: 180 ° C, 8 minutes) to form a mask adhesive layer. Thereafter, a polyester protective film having a thickness of 100 μm which was subjected to polysilicon oxide release treatment was attached to the surface of the mask adhesive layer, and aged at room temperature (20 ± 3 ° C) for 3 days to stabilize the adhesive force. The thickness of the reticle adhesive layer formed was 0.3 mm. A protective film is attached to the other end surface of the above-mentioned protective film frame via a film adhesive layer to form a protective film.

With respect to the obtained film, the peeling evaluation and the deformation evaluation of the mask were performed in the same manner as in Example 1. Each result is shown in Table 1.

[Industrial availability]

According to the present invention, the residue on the mask after exposure can be sufficiently prevented. The present invention can be preferably used in an optical lithography step of an IC (integrated circuit), an LSI (large-scale integrated circuit), an LCD (Liquid Crystal Display), or the like, and can be particularly used in exposure using a necessary high resolution. The photolithographic lithography step of the excimer laser is preferably used when a photolithography step of exposure to ultraviolet light of 200 nm or less is used.

Claims (7)

A protective film comprising: a protective film frame; a protective film body stretched on one end surface of the protective film frame; and a mask adhesive layer containing the other end surface attached to the protective film frame The non-crosslinking type acrylic adhesive; the thickness of the mask adhesive layer is 0.25 mm or more and 3.0 mm or less, and the content of the compound having a weight average molecular weight of 800 or less in the non-crosslinked acrylic adhesive is 18% by mass or less, the non-crosslinking type acrylic adhesive has a glass transition temperature of less than -25 ° C, and the non-crosslinked acrylic adhesive contains an acrylic polymer (A) and an acrylic base polymer. (B) The weight average molecular weight of the acrylic polymer (A) is 850 or more and 70,000 or less, and the weight average molecular weight of the acrylic base polymer (B) is 10,000 or more and 500,000 or less. The protective film of claim 1, wherein the non-crosslinked acrylic adhesive has an elastic modulus of ²⁰ mN/mm ² or more and 180 mN/mm ² or less. The coating film of claim 1, wherein the acrylic polymer (A) has a glass transition temperature of -30 ° C or lower, and the acrylic base polymer (B) has a glass transition temperature of -25 ° C or higher. The protective film of claim 1, wherein the content of the acrylic polymer (A) in the non-crosslinked acrylic adhesive is 15 to 80% by mass. The coating film of claim 1, wherein the acrylic polymer (A) is a polymer or copolymer of an alkyl (meth)acrylate having an alkyl group having 1 to 14 carbon atoms. A reticle with a protective film mounted with a protective film according to any one of claims 1 to 5. A method of manufacturing a semiconductor device, comprising the steps of: exposing a substrate using a photomask as claimed in claim 6.