JP2006194962A - Material for forming protective film, laminate and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for forming a protective film capable of forming a protective film excellent in substance shielding property, and to provide a laminated body and a resist pattern forming method using the material for forming a protective film. <P>SOLUTION: The material for forming a protective film removable with an alkaline developer for a resist layer is obtained by dissolving in an organic solvent an alkali-soluble resin (A1) including a constitutional unit (a0-1) derived from acrylic acid, having no cyclic structure and having an alcoholic hydroxyl group in a side chain and a constitutional unit (a1) including an alicyclic group having a fluorinated hydroxyalkyl group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a protective film forming material used for forming a protective film for protecting the resist layer on a resist layer, a laminate using the protective film forming material, and a resist pattern forming method.

In recent years, in the semiconductor device field, the wavelength of exposure light has been shortened along with the high integration and miniaturization of devices. Specifically, in the past, ultraviolet rays typified by g-line and i-line were used, but now KrF excimer laser (248 nm) has been introduced, and ArF excimer laser (193 nm) has begun to be introduced. Yes. In addition, studies have been conducted on shorter wavelength F ₂ excimer lasers (157 nm), EUV (extreme ultraviolet rays), electron beams, X-rays, and the like.
In addition, as one of the resist materials that satisfy the conditions of high resolution capable of reproducing a pattern with fine dimensions, a base material component that has film forming ability and changes in alkali solubility by the action of an acid, and exposure. A chemically amplified resist containing an acid generator component that generates an acid is known. Chemically amplified resists include a negative type in which alkali solubility is reduced by exposure and a positive type in which alkali solubility is increased by exposure.

However, when a chemically amplified resist is used, problems such as a decrease in sensitivity, a deterioration in the shape of the resist pattern, and a decrease in resolution may occur.
One of the causes of such problems is contamination (environmental influence) on the resist layer of a basic substance such as amine existing in the environment. That is, in the chemically amplified resist, due to the reaction mechanism of utilizing the action of acid, the acid is deactivated by the contamination of the basic substance, and its performance (sensitivity, shape, resolution, etc.) is affected. In addition, such environmental influence is also caused by the length of the process delay, for example, the time from the application of the resist to the exposure and the time from the exposure to the post-exposure heating (PEB). The degree differs, and this causes a difference in performance between lots, and changes in sensitivity, shape, resolution, and the like.

As one method of suppressing such a problem, a method of providing a protective film on a resist layer is performed. As a material for forming the protective film, a composition containing a water-soluble film-forming resin is generally used (see, for example, Patent Document 1).
JP-A-8-15859

  However, the protective film formed using such a material cannot sufficiently block the permeation of the substance between the resist layer and the environment, and the basic substance in the environment enters the resist layer. The effect of reducing the environmental impact due to was not sufficient.

  The present invention has been made to solve the above-described problems, and provides a protective film forming material excellent in substance blocking properties, a laminate using the protective film forming material, and a resist pattern forming method. For the purpose.

In order to achieve the above object, the present invention employs the following configuration.
That is, the first aspect of the present invention is a fluorinated structural unit (a0-1) derived from acrylic acid and having no cyclic structure and having an alcoholic hydroxyl group in the side chain. A protective film formed by dissolving an alkali-soluble resin (A1) containing a structural unit (a1) containing an alicyclic group having a hydroxyalkyl group in an organic solvent and removable with an alkali developer for a resist layer Material.
Moreover, the 2nd aspect of this invention contains the base material component (A ') from which alkali solubility changes with the effect | action of an acid, and the acid generator component (B') which generate | occur | produces an acid by exposure on a board | substrate. A laminate in which a resist layer and a protective film made of the protective film-forming material of the first aspect are sequentially laminated.
Further, according to a third aspect of the present invention, after a resist layer is formed on a substrate, a protective film is formed on the resist layer using the protective film-forming material of the first aspect. The resist pattern is formed by selectively exposing the resist layer through a PEB (post-exposure heating) and then removing the protective film and developing the resist layer with an alkali developer. It is.

  In the claims and the specification, the term “exposure” includes not only light irradiation but also general radiation irradiation such as electron beam irradiation.

  According to the present invention, there are provided a protective film forming material capable of forming a protective film having excellent substance blocking properties, a laminate using the protective film forming material, and a resist pattern forming method.

The protective film-forming material of the present invention is a fluorinated component unit (a0-1) derived from acrylic acid and having no cyclic structure and having an alcoholic hydroxyl group in the side chain. An alkali-soluble resin (A1) containing a structural unit (a1) containing an alicyclic group having a hydroxyalkyl group (hereinafter also referred to as component (A1)) is dissolved in an organic solvent. . The protective film is formed by applying the protective film-forming material on the resist layer and then heating. The protective film can be removed with an alkaline developer. That is, the protective film is soluble in an alkali developer and can be removed by dissolving with an alkali developer.
Here, the fact that the protective film can be removed with an alkali developer means that, for example, the dissolution rate in a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution (23 ° C.) is 10 nm / second or more. It shall be.

Furthermore, when the protective film formed using the protective film forming material of the present invention is used for immersion exposure described later, the protective film is preferably insoluble in an immersion medium for immersion exposure. Thereby, the contact between the resist film and the immersion medium can be prevented, and the performance degradation of the resist film due to the contact and the contamination of the immersion medium and the exposure apparatus can be prevented.
Here, “insoluble in the immersion medium” means, for example, that the protective film does not dissolve within 60 seconds when immersed in an immersion medium (23 ° C.) using the protective film.
In the present invention, it is particularly preferable that the component (A1) is insoluble in water.

<(A1) component>
The component (A1) is a structural unit derived from acrylic acid and having no cyclic structure, the structural unit (a0-1) having an alcoholic hydroxyl group in the side chain, and a fluorinated hydroxyalkyl group. It is alkali-soluble resin containing the structural unit (a1) containing the alicyclic group which has.

The component (A1) is preferably soluble in alcohol having 4 to 6 carbon atoms. As a result, alcohol having 4 to 6 carbon atoms can be used as the organic solvent for dissolving the component (A1), and the mixing phenomenon between the resist layer and the protective film can be prevented as described in the section of the organic solvent described later.
Here, “soluble in alcohol having 4 to 6 carbon atoms” means, for example, that the concentration of alcohol having 4 to 6 carbon atoms is 2.5% by mass with respect to component (A1) under the condition of 23 ° C. When added in such a manner, it means that the component (A1) is completely dissolved.

  When the protective film forming material is used for immersion exposure, the component (A1) is preferably insoluble in the immersion medium.

In the claims and specification, the “structural unit” refers to a monomer unit constituting a polymer (resin).
The “structural unit derived from acrylic acid” means a structural unit formed by cleavage of an ethylenic double bond of acrylic acid. “Structural unit derived from acrylic acid” includes a structural unit in which the hydrogen atom bonded to the α-position carbon atom is substituted with another substituent such as an alkyl group, or a hydrogen atom bonded to the α-position carbon atom. Also included are structural units derived from acrylic esters. The “structural unit derived from an acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of an acrylate ester. The “structural unit derived from an acrylate ester” has a concept including those in which the hydrogen atom at the α-position is substituted with another substituent such as an alkyl group.
In the “structural unit derived from acrylic acid” and the “structural unit derived from acrylate ester”, the term “α-position (α-position carbon atom)” means that a carboxy group is present unless otherwise specified. It is a bonded carbon atom.
In the claims and specification, the “alkyl group” includes a linear, branched or cyclic alkyl group unless otherwise specified.

・ Structural unit (a0-1)
In the material for forming a protective film of the present invention, for the effect of the present invention, the component (A1) is a structural unit derived from acrylic acid and having no cyclic structure, and an alcoholic hydroxyl group in the side chain. It is necessary to have a structural unit (a0-1) having

In the structural unit (a0-1), “having no cyclic structure” means having no alicyclic group or aromatic group.
As the structural unit (a0-1), for example, a structural unit in which a hydroxyalkyl group is bonded to the α-position carbon atom of the main chain (the portion where the ethylenic double bond of acrylic acid is cleaved), Examples include a structural unit constituting an ester by substituting a hydrogen atom of a carboxy group of acrylic acid. In the component (A1), it is preferable that any one or both of them are present as the structural unit (a0-1).
Here, when a hydroxyalkyl group is not bonded to the α-position, an alkyl group, a fluorinated alkyl group, or a fluorine atom may be bonded to the α-position carbon atom instead of the hydrogen atom.
The alkyl group bonded to the α-position carbon atom is preferably a lower alkyl group having 5 or less carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, Examples include a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and the like, and a methyl group is preferable.
The fluorinated alkyl group bonded to the α-position carbon atom is preferably a group in which one or more hydrogen atoms of a lower alkyl group having 5 or less carbon atoms are substituted with a fluorine atom. Specific examples of the alkyl group in the fluorinated alkyl group are the same as the specific examples of the alkyl group. Further, the hydrogen atoms substituted with fluorine atoms may be a part or all of the hydrogen atoms constituting the alkyl group.
Of those capable of bonding to the α-position, a hydrogen atom or an alkyl group is preferable, a hydrogen atom or a methyl group is particularly preferable, and a hydrogen atom is most preferable.

  As the structural unit (a0-1), a structural unit represented by the following general formula (3) is particularly preferable. A protective film obtained using a resin having such a structural unit has a high substance barrier property and is easily removed with an alkaline developer. Further, since it is insoluble in an immersion medium such as water, it is excellent for immersion exposure.

［式中、Ｒ^１は水素原子、アルキル基、フッ素化アルキル基、フッ素原子またはヒドロキシアルキル基であり、Ｒ^２は、水素原子、アルキル基、またはヒドロキシアルキル基であり、かつＲ^１、Ｒ^２の少なくとも一方はヒドロキシアルキル基である。］

[Wherein, R ¹ represents a hydrogen atom, an alkyl group, a fluorinated alkyl group, a fluorine atom or a hydroxyalkyl group, R ² represents a hydrogen atom, an alkyl group or a hydroxyalkyl group, and R ¹ , R ² At least one of these is a hydroxyalkyl group. ]

In R ¹ , the hydroxyalkyl group is preferably a hydroxyalkyl group having 10 or less carbon atoms, more preferably a hydroxyalkyl group having 2 to 8 carbon atoms, and most preferably a hydroxymethyl group or a hydroxyethyl group. . The number of hydroxyl groups and the bonding position in the hydroxyalkyl group are not particularly limited, but are usually one and preferably bonded to the terminal of the alkyl group.
In R ¹ , the alkyl group is preferably an alkyl group having 10 or less carbon atoms, more preferably an alkyl group having 2 to 8 carbon atoms, and most preferably an ethyl group or a methyl group.
In R ¹ , the fluorinated alkyl group is preferably a lower alkyl group having 5 or less carbon atoms (preferably an ethyl group or a methyl group) in which part or all of the hydrogen atoms are substituted with fluorine.
In R ² , examples of the alkyl group and hydroxyalkyl group include the same groups as those described for R ¹ .

As the structural unit represented by the formula (3), specifically, a structural unit derived from (α-hydroxyalkyl) acrylic acid, a structural unit derived from (α-hydroxyalkyl) acrylic acid alkyl ester, ( and a structural unit derived from an α-alkyl) acrylic acid hydroxyalkyl ester.
Among these, from the point that the film density is particularly easily improved and the effect of the present invention is excellent, it is derived from a structural unit derived from (α-hydroxyalkyl) acrylic acid alkyl ester and / or from (α-alkyl) acrylic acid hydroxyalkyl ester. It is preferable that the structural unit is included.
As a structural unit derived from (α-hydroxyalkyl) acrylic acid alkyl ester, in particular, a structural unit derived from (α-hydroxymethyl) -acrylic acid ethyl ester or (α-hydroxymethyl) -acrylic acid methyl ester. Is preferred.
As the structural unit derived from (α-alkyl) acrylic acid hydroxyalkyl ester, a structural unit derived from (α-methyl) acrylic acid hydroxyethyl ester or (α-methyl) acrylic acid hydroxymethyl ester is particularly preferable. .

The structural unit (a0-1) can be used alone or in combination of two or more.
10-80 mol% is preferable with respect to the sum total of all the structural units which comprise resin (A1), and the ratio of the structural unit (a0-1) in resin (A1), 15-60 mol% is more preferable, 15 -40 mol% is most preferred. By setting it as the said range, the solubility with respect to a developing solution will be excellent.

・ Structural unit (a1)
In addition to the structural unit (a0-1), the component (A1) needs to further include a structural unit (a1) containing an alicyclic group having a fluorinated hydroxyalkyl group. By having the structural unit (a1), it is possible to prevent the protective film from being swollen with water or the like during rinsing or in an immersion process described later. Moreover, favorable solubility can be obtained with respect to the organic solvent.
The fluorinated hydroxyalkyl group is an alkyl group having a hydroxy group in which part or all of the hydrogen atoms of the alkyl group are substituted with fluorine. In the group, the hydrogen atom of the hydroxyl group is easily liberated by fluorination.
In the fluorinated hydroxyalkyl group, the alkyl group is linear or branched, and the number of carbon atoms is not particularly limited, but is, for example, 1 to 20, preferably 4 to 16. The number of hydroxyl groups is not particularly limited, but is usually one.
In particular, in the alkyl group, a fluorinated alkyl group and / or a fluorine atom is bonded to the α-position carbon atom to which the hydroxy group is bonded (in this case, the α-position carbon atom of the hydroxyalkyl group). Those are preferred. In the fluorinated alkyl group bonded to the α-position, it is preferable that all of the hydrogen atoms of the alkyl group are substituted with fluorine.

The alicyclic group may be monocyclic or polycyclic, but is preferably a polycyclic group. Moreover, an alicyclic hydrocarbon group is preferable. Moreover, it is preferable that it is saturated. Moreover, it is preferable that carbon number of an alicyclic group is 5-15.
Specific examples of the alicyclic group include the following. That is, examples of the monocyclic group include groups in which one hydrogen atom has been removed from a cycloalkane. Examples of the polycyclic group include groups in which one or two hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane or the like.
More specifically, examples of the monocyclic group include groups in which one or two hydrogen atoms have been removed from cyclopentane or cyclohexane, and groups in which two hydrogen atoms have been removed from cyclohexane are preferred.
Examples of the polycyclic group include groups in which one or two hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.
In addition, such polycyclic groups are appropriately selected from those proposed as many constituting acid dissociable, dissolution inhibiting groups in, for example, positive photoresist composition resins for ArF excimer laser processes. Can be used.
Of these, groups in which two hydrogen atoms have been removed from cyclohexane, adamantane, norbornane, and tetracyclododecane are preferred because they are readily available in the industry.
Of these exemplified monocyclic groups and polycyclic groups, groups in which two hydrogen atoms have been removed from norbornane are particularly preferred.

  The structural unit (a1) is preferably a structural unit derived from acrylic acid, more preferably a structural unit derived from an acrylate ester, and particularly an ester group [—C (O) O— of the acrylate ester. ] The structure (The structure where the hydrogen atom of the carboxy group is substituted by the said alicyclic group) which the said alicyclic group couple | bonded with is preferable.

  As the structural unit (a1), more specifically, those represented by the following general formula (1) are preferred.

［式中、Ｒは水素原子、アルキル基、フッ素化アルキル基またはフッ素原子であり、ｍ、ｎ、ｐはそれぞれ独立して１〜５の整数である。］

[Wherein, R represents a hydrogen atom, an alkyl group, a fluorinated alkyl group or a fluorine atom, and m, n and p are each independently an integer of 1 to 5. ]

R is the same as R ^{1 in the} general formula (3).
In R, a hydrogen atom or an alkyl group is preferable, a hydrogen atom or a methyl group is particularly preferable, and a hydrogen atom is most preferable.
N, m, and p are each preferably 1.

  Among those represented by the general formula (1), α, α′-bis- (trifluoromethyl) -bicyclo [2.2.1] hept-5-ene-2-ethanol acrylate (of the following [Chemical Formula 16] The structural unit derived from (i) is preferred because it can be easily synthesized.

The structural unit (a1) can be used alone or in combination of two or more.
10-80 mol% is preferable with respect to the sum total of all the structural units which comprise resin (A1), and, as for the ratio of the structural unit (a1) in resin (A1), 20-70 mol% is more preferable, and 30-60 Mole% is most preferred. By setting it as the said range, the solubility with respect to the organic solvent will be excellent.

・ Structural unit (a0-2)
In addition to the structural unit (a0-1) and the structural unit (a1), the resin (A1) further has a structural unit (a0-2) derived from an acrylate ester and containing a hydroxyl group-containing alicyclic group. You may do it. By having the structural unit (a0-2), the adhesion to the resist film is improved.
Here, the structural unit (a0-2) is clearly distinguished from the structural unit (a0-1) having no cyclic structure by having an alicyclic group.
In the structural unit (a0-2), the hydroxyl group-containing alicyclic group is a group in which a hydroxyl group is bonded to the alicyclic group. It is preferable that 1-3 hydroxyl groups are couple | bonded, for example, More preferably, it is one. Moreover, the C1-C4 alkyl group may couple | bond with the alicyclic group.
The hydroxyl group-containing alicyclic group is preferably bonded to the ester group (—C (O) O—) of the acrylate ester.
Here, the alicyclic group may be monocyclic or polycyclic, but is preferably a polycyclic group. Moreover, an alicyclic hydrocarbon group is preferable. Moreover, it is preferable that it is saturated. Moreover, it is preferable that carbon number of an alicyclic group is 5-15.

Specific examples of the alicyclic group include the following.
That is, examples of the monocyclic group include groups in which one hydrogen atom has been removed from a cycloalkane. Examples of the polycyclic group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like.
More specifically, examples of the monocyclic group include groups in which one hydrogen atom has been removed from cyclopentane or cyclohexane, and a cyclohexyl group is preferred.
Examples of the polycyclic group include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
In addition, such polycyclic groups are appropriately selected from those proposed as many constituting acid dissociable, dissolution inhibiting groups in, for example, positive photoresist composition resins for ArF excimer laser processes. Can be used.
Among these, a cyclohexyl group, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are preferred because they are easily available in the industry.
Among these exemplified monocyclic groups and polycyclic groups, a cyclohexyl group and an adamantyl group are preferable, and an adamantyl group is particularly preferable.

In the structural unit (a0-2), other substituents may be bonded to the α-position (α-position carbon atom) of the acrylate ester instead of the hydrogen atom. The substituent is preferably an alkyl group, a fluorinated alkyl group, or a fluorine atom.
These descriptions are the same as the alkyl group, fluorinated alkyl group, or fluorine atom which may be bonded to the α-position carbon atom described in the structural unit (a0-1). Of those capable of bonding to the α-position, a hydrogen atom or an alkyl group is preferable, a hydrogen atom or a methyl group is particularly preferable, and a hydrogen atom is most preferable.

  As a specific example of the structural unit (a0-2), for example, a structural unit represented by the following general formula (2) is preferable.

［式中、Ｒは水素原子、アルキル基、フッ素化アルキル基またはフッ素原子であり、ｑは１〜３の整数である。］

[Wherein, R represents a hydrogen atom, an alkyl group, a fluorinated alkyl group or a fluorine atom, and q represents an integer of 1 to 3. ]

R is the same as R ^{1 in the} general formula (3). In the general formula (2), R is most preferably a hydrogen atom.
Moreover, q is an integer of 1 to 3, but is preferably 1.
Further, the bonding position of the hydroxyl group is not particularly limited, but is preferably bonded to the position of the 3rd position of the adamantyl group.

The structural unit (a0-2) can be used alone or in combination of two or more.
In the component (A1), the proportion of the structural unit (a0-2) is preferably from 5 to 50 mol%, more preferably from 10 to 40 mol%, based on the total of all the structural units constituting the component (A1). More preferred is ~ 35 mol%.

・ Structural unit (a2)
The component (A1) is derived from an acrylate ester containing a lactone-containing monocyclic or polycyclic group in addition to the structural unit (a0-1), the structural unit (a1), and the structural unit (a0-2). The structural unit (a2) may be included.

The lactone-containing monocyclic or polycyclic group of the structural unit (a2) is effective for enhancing the adhesion of the protective film to the resist film and the hydrophilicity with the developer. Moreover, it can suppress that a protective film swells with water.
Here, the lactone-containing monocyclic or polycyclic group refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.

As the structural unit (a2), any structural unit can be used without particular limitation as long as it has both such a lactone structure (—O—C (O) —) and a cyclic group.
Specifically, examples of the lactone-containing monocyclic group include groups in which one hydrogen atom has been removed from γ-butyrolactone. Examples of the lactone-containing polycyclic group include groups in which one hydrogen atom has been removed from a bicycloalkane, tricycloalkane, or tetracycloalkane having a lactone ring. In particular, a group obtained by removing one hydrogen atom from a lactone-containing tricycloalkane having the following structural formula is advantageous in that it is easily available industrially.

  In the structural unit (a2), those having a lactone-containing polycyclic group are preferred, and those having norbornane lactone are particularly preferred.

In the structural unit (a2), other substituents may be bonded to the α-position (α-position carbon atom) instead of a hydrogen atom. The substituent is preferably an alkyl group, a fluorinated alkyl group, or a fluorine atom.
These explanations are the same as those of R ^{1 in} the general formula (3), and among those which can be bonded to the α-position, a hydrogen atom or an alkyl group is preferred, and in particular, a hydrogen atom or a methyl group is preferred. A hydrogen atom is preferred and most preferred.

  More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

［式中、Ｒは前記と同じである。Ｒ’は水素原子、アルキル基、または炭素数１〜５のアルコキシ基であり、ｍは０または１の整数である。］

[Wherein, R is the same as defined above. R ′ is a hydrogen atom, an alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is an integer of 0 or 1. ]

In general formulas (a2-1) to (a2-5), the alkyl group for R and R ′ is the same as the alkyl group for R in the structural unit (a1).
In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Below, the specific structural unit of the said general formula (a2-1)-(a2-5) is illustrated.

In general formulas (a2-1) to (a2-5), R ′ is preferably a hydrogen atom in view of industrial availability.
Among these, it is preferable to use at least one selected from general formulas (a2-1) to (a2-5), and at least one selected from general formulas (a2-1) to (a2-3). It is preferable to use more than one species. Specifically, chemical formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1), (a2-3) -2), at least one selected from (a2-3-9) and (a2-3-10) is preferably used.

As the structural unit (a2), one type may be used alone, or two or more types may be used in combination.
Although the structural unit (a2) is not an essential component, when the structural unit (a2) is included, the proportion of the structural unit (a2) in the resin (A11) is the sum of all the structural units constituting the resin (A11). On the other hand, 5 to 50 mol% is preferable, 5 to 40 mol% is more preferable, and 5 to 20 mol% is most preferable.

  The component (A1) can be obtained, for example, by radical polymerization of a monomer for deriving each structural unit by a conventional method.

  (A1) The mass average molecular weight of a component becomes like this. Preferably it is 2000-30000, More preferably, it is 2000-10000, Most preferably, it is 3000-8000. When the mass average molecular weight is 2000 or more, the film formability of the protective film is good. Moreover, the solubility with respect to an alkali developing solution is favorable in the mass mean molecular weight being 30000 or less.

The component (A1) contained in the protective film-forming material may be a single type or a mixture of two or more types.
The content of the component (A1) in the protective film forming material may be adjusted according to the resist film thickness to be formed.

<Organic solvent>
The material for forming a protective film of the present invention is obtained by dissolving the component (A1) and an optional component described later in an organic solvent.
The organic solvent is not particularly limited as long as it can dissolve each component to be used to form a uniform solution. In the present invention, when the organic solvent contains at least one selected from the group consisting of alcohols having 4 to 6 carbon atoms, the effect of preventing the mixing phenomenon is high, and the resin (A11) described above ( A1) It is preferable in terms of excellent solubility of the component and high safety against the environment. The mixing phenomenon is a phenomenon in which the component of the protective film forming material and the component of the resist layer are mixed. One of the causes of the mixing phenomenon is that when the protective film is formed, the resist layer is dissolved by the organic solvent in the protective film forming material. The compatibility with the resist layer is low, so that the mixing phenomenon at the interface between the protective film and the resist layer can be prevented.

As the alcohol having 4 to 6 carbon atoms, a monohydric alcohol is more preferable, and among them, a primary monohydric alcohol is most preferable.
The boiling point of the alcohol having 4 to 6 carbon atoms is preferably 80 to 160 ° C, more preferably 90 to 150 ° C, and most preferably 100 to 135 ° C from the viewpoint of applicability. Here, the monohydric alcohol means a case where the number of hydroxyl groups contained in the alcohol molecule is one, and a polyhydric alcohol and its derivatives (for example, a hydrogen atom of some hydroxyl groups is a substituent such as an alkyl group). Is not included).
Specific examples of the alcohol having 4 to 6 carbon atoms include n-amyl alcohol (boiling point 138.0 ° C.), s-amyl alcohol (boiling point 119.3 ° C.), t-amyl alcohol (101.8 ° C.), isoamyl alcohol. (Boiling point 130.8 ° C), isobutyl alcohol (boiling point 107.9 ° C), 2-ethylbutanol (boiling point 147 ° C), neopentyl alcohol (boiling point 114 ° C), n-butanol (boiling point 117.7 ° C), s- Butanol (boiling point 99.5 ° C), t-butanol (boiling point 82.5 ° C), n-hexanol (boiling point 157.1 ° C), 2-methyl-1-butanol (boiling point 128.0 ° C), 2-methyl- Examples include 2-butanol (boiling point 112.0 ° C.) and 4-methyl-2-pentanol (boiling point 131.8 ° C.).
In the present invention, in particular, the organic solvent may contain at least one selected from the group consisting of isobutyl alcohol (2-methyl-1-propanol), 4-methyl-2-pentanol and n-butanol. preferable.
In the organic solvent, the proportion of the alcohol having 4 to 6 carbon atoms is preferably 50 to 100% by mass, more preferably 75 to 100% by mass, further preferably 90 to 100% by mass, and most preferably 100% by mass.

The organic solvent may contain an organic solvent other than the above as long as the effects of the present invention are not impaired. As such an organic solvent, one or two or more kinds of conventionally known solvents for chemically amplified resists can be appropriately selected and used. For example, lactones such as γ-butyrolactone, Ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone; ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, or dipropylene glycol monoacetate All alcoholic hydroxyl groups in polyhydric alcohols and their derivatives are substituted with alkoxy groups (methoxy group, ethoxy group, propoxy group, butoxy group, etc.) Chain ethers; Cyclic ethers such as dioxane; Esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate And so on.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The mixing ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 6: 4. It is preferable to be within the range.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2.
In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.

  Although the amount of the organic solvent used is not particularly limited, it is a concentration that can be applied on the resist film, is set as appropriate according to the coating film thickness, and is used so that the solid content concentration is in the range of 1 to 20% by mass. It is preferable and 1-15 mass% is more preferable.

<Other ingredients>
The protective film-forming material of the present invention may further contain an acid generator component (B) that generates an acid upon exposure (hereinafter referred to as component (B)). Thereby, since the crosslinking reaction with (C) component and (A1) component mentioned later can be produced, the effect of this invention improves further.
(B) It does not specifically limit as a component, The thing proposed so far as an acid generator for chemically amplified resists can be used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.
Examples of the onium salt acid generator include compounds represented by the following general formula (b-1) or (b-2).

［式中、Ｒ^１”〜Ｒ^３”は、それぞれ独立に、アリール基またはアルキル基を表し；Ｒ^４”は、直鎖、分岐または環状のアルキル基またはフッ素化アルキル基を表し；Ｒ^１”〜Ｒ^３”のうち少なくとも１つはアリール基を表し、Ｒ^５”〜Ｒ^６”のうち少なくとも１つはアリール基を表す。］

[Wherein, R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group; R ⁴ ″ represents a linear, branched or cyclic alkyl group or a fluorinated alkyl group; R ¹ ″ to R ³ "at least one of represents an aryl ^group, R 5" represents at least one aryl group of to R ⁶ ".]

In formula (b-1), R ¹ ″ to R ³ ″ each independently represents an aryl group or an alkyl group. At least one of R ¹ ″ to R ³ ″ represents an aryl group. Of R ¹ ″ to R ³ ″, two or more are preferably aryl groups, and most preferably all R ¹ ″ to R ³ ″ are aryl groups.
The aryl group for R ¹ ″ to R ³ ″ is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, in which part or all of the hydrogen atoms are alkyl groups, alkoxy groups It may or may not be substituted with a group, a halogen atom or the like. The aryl group is preferably an aryl group having 6 to 10 carbon atoms because it can be synthesized at a low cost. Specific examples include a phenyl group and a naphthyl group.
The alkyl group that may be substituted for the hydrogen atom of the aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and is a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group. Is most preferred.
The alkoxy group that may be substituted for the hydrogen atom of the aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and most preferably a methoxy group or an ethoxy group.
The halogen atom that may be substituted for the hydrogen atom of the aryl group is preferably a fluorine atom.
The alkyl group for R 1 ^{"~R 3",} is not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost.
Among these, it is most preferable that all of R ^{1 to} R ³ are phenyl groups.

In formula (b-2), R ⁵ ″ to R ⁶ ″ each independently represents an aryl group or an alkyl group. At least one of R ⁵ ″ to R ⁶ ″ represents an aryl group. Of R ⁵ ″ to R ⁶ ″, two or more are preferably aryl groups, and most preferably R ⁵ ″ to R ⁶ ″ are all aryl groups.
As the aryl group for R ⁵ ″ to R ⁶ ″, the same as the aryl groups for R ¹ ″ to R ³ ″ can be used.
Examples of the alkyl group for R ⁵ ″ to R ⁶ ″ include the same as the alkyl group for R ¹ ″ to R ³ ″.
Among these, it is most preferable that all of R ⁵ ″ to R ⁶ ″ are phenyl groups.

R ⁴ ″ in the general formulas (b-1) and (b-2) is most preferably a linear or cyclic alkyl group or a fluorinated alkyl group.
The linear alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.
The cyclic alkyl group is a cyclic group as indicated by R ¹ , preferably having 4 to 15 carbon atoms, more preferably 4 to 10 carbon atoms, and more preferably 6 to 6 carbon atoms. 10 is most preferred.
The fluorinated alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms. Also. The fluorination rate of the fluorinated alkyl group (ratio of fluorine atoms in the alkyl group) is preferably 10 to 100%, more preferably 50 to 100%, and particularly those in which all hydrogen atoms are substituted with fluorine atoms. Since the strength of the acid is increased, it is preferable.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethane. Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethane Sulfonate, its heptafluoropropane sulphonate or its Nafluorobutane sulfonate, trifluoromethane sulfonate of monophenyldimethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of diphenyl monomethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, (4- Trifluoromethanesulfonate of methylphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of (4-methoxyphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, Methoxynaphthyl Fluorination of diphenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-tert-butyl) phenylsulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate Examples thereof include onium salts having an alkyl sulfonate ion as an anion. Moreover, the onium salt which replaced the anion part of the above-mentioned onium salt by the alkyl sulfonate ion which is not fluorinated, such as methanesulfonate, n-propanesulfonate, n-butanesulfonate, n-octanesulfonate, may be sufficient.

  Moreover, what replaced the anion part by the anion part represented by the following general formula (b-3) or (b-4) in the said general formula (b-1) or (b-2) can also be used. (The cation moiety is the same as (b-1) or (b-2)).

［式中、Ｘ”は、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｙ”、Ｚ”は、それぞれ独立に、少なくとも１つの水素原子がフッ素原子で置換された炭素数１〜１０のアルキル基を表す。］

[Wherein X ″ represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; Y ″ and Z ″ each independently represent at least one hydrogen atom as a fluorine atom; Represents an alkyl group having 1 to 10 carbon atoms and substituted with

X ″ is a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group has 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms, Preferably it is C3.
Y ″ and Z ″ are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkyl group has 1 to 10 carbon atoms, preferably It is C1-C7, More preferably, it is C1-C3.
The carbon number of the alkylene group of X ″ or the carbon number of the alkyl group of Y ″ and Z ″ is preferably as small as possible because the solubility in the resist solvent is good within the above carbon number range.
In addition, in the alkylene group of X ″ or the alkyl group of Y ″ and Z ″, as the number of hydrogen atoms substituted with fluorine atoms increases, the strength of the acid increases, and high-energy light or electron beam of 200 nm or less The ratio of fluorine atoms in the alkylene group or alkyl group, that is, the fluorination rate is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all. Are a perfluoroalkylene group or a perfluoroalkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Specific examples of oxime sulfonate acid generators include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyloxy). Imino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzenesulfonyl) Oxyimino) -2,4-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzylcyanide, α- ( 2-Chlorobenzenesulfonyloxyimino) 4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclo Pentenyl acetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctene Acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclope Nthenyl acetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p- Butoxy phenylacetonitrile, alpha-(propylsulfonyl oxyimino)-p-methylphenyl acetonitrile, alpha-like (methylsulfonyloxyimino)-p-bromophenyl acetonitrile. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

  An oxime sulfonate acid generator represented by the following chemical formula can also be used.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (compound A) and 1,4-bis (phenylsulfonyldiazomethylsulfonyl) having the following structure. Butane (compound B), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C), 1,10-bis (phenylsulfonyldiazomethylsulfonyl) decane (compound D), 1,2-bis (cyclohexylsulfonyl) Diazomethylsulfonyl) ethane (compound E), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) propane (compound F), 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (compound G), 1,10- Bis (cyclohex Le diazomethylsulfonyl) decane (compound H) and the like.

In the present invention, from the viewpoint of the reactivity between the component (A) and the component (C), it is preferable to use an onium salt having a fluorinated alkyl sulfonate ion as an anion as the component (B).
As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it within the above range, pattern formation is sufficiently performed. Moreover, since a uniform solution is obtained and storage stability becomes favorable, it is preferable.

(C) Crosslinking agent component The protective film-forming material of the present invention may further contain a crosslinking agent component (C) (hereinafter sometimes referred to as (C) component) as an optional component. Thereby, bridge | crosslinking arises between (A1) component and (C) component, the film | membrane density of a protective film further increases, and substance blocking property improves.

The component (C) is not particularly limited, and can be arbitrarily selected from the crosslinking agent components used in the chemically amplified negative resist compositions known so far.
Specifically, for example, 2,3-dihydroxy-5-hydroxymethylnorbornane, 2-hydroxy-5,6-bis (hydroxymethyl) norbornane, cyclohexanedimethanol, 3,4,8 (or 9) -trihydroxytri Aliphatic cyclic carbonization having a hydroxyl group or a hydroxyalkyl group or both such as cyclodecane, 2-methyl-2-adamantanol, 1,4-dioxane-2,3-diol, 1,3,5-trihydroxycyclohexane Examples thereof include hydrogen and oxygen-containing derivatives thereof.
In addition, amino group-containing compounds such as melamine, acetoguanamine, benzoguanamine, urea, ethylene urea, glycoluril are reacted with formaldehyde or formaldehyde and a lower alcohol, and the hydrogen atom of the amino group is replaced with a hydroxymethyl group or a lower alkoxymethyl group. Compounds.
Of these, those using melamine are melamine crosslinking agents, those using urea are urea crosslinking agents, those using ethylene urea are ethylene urea crosslinking agents, and those using glycoluril are glycoluril crosslinking agents It is called an agent.
Specific examples include hexamethoxymethylmelamine, bismethoxymethylurea, bismethoxymethylbismethoxyethyleneurea, tetramethoxymethylglycoluril, tetrabutoxymethylglycoluril and the like.

  The component (C) is particularly preferably at least one selected from melamine crosslinking agents, urea crosslinking agents, ethyleneurea crosslinking agents, and glycoluril crosslinking agents. Particularly preferred is a glycoluril-based crosslinking agent.

As the glycoluril-based crosslinking agent, glycoluril substituted at the N-position with a hydroxyalkyl group and / or a lower alkoxyalkyl group which is a crosslinking group is preferable.
More specifically, examples of the glycoluril-based crosslinking agent include mono-, di-, tri- and tetrahydroxymethyl glycolurils, mono-, di-, tri- and / or tetramethoxymethylated glycolurils, mono-, di-, tri- and / or tetra- Examples include ethoxymethyl glycoluril, mono, di, tri and / or tetrapropoxymethylated glycoluril, mono, di, tri and / or tetrabutoxymethylated glycoluril. "Mono, di, tri and / or tetra ..." indicates that one or more of mono-, di-, tri-, and tetra-forms may be included, particularly A tri- or tetra-isomer is preferred.
Mono, di, tri and / or tetramethoxymethylated glycoluril and mono, di, tri and / or tetrabutoxymethylated glycoluril are also preferred.
From the viewpoint of contrast and resolution, mono, di, tri and / or tetramethoxymethylated glycoluril is most preferable. This crosslinking agent can be obtained, for example, as a commercial product “Mx270” (product name, manufactured by Sanwa Chemical Co., Ltd.). These are mostly tri- and tetra-isomers, and are a mixture of monomers, dimers and trimers.

  (C) The compounding quantity of a component shall be 3-15 mass parts with respect to 100 mass parts of (A1) component, Preferably it is 5-10 mass parts. By setting it to the lower limit value or more, the effect of blending the component (C) can be obtained, and by setting the upper limit value or less, the protective film can be sufficiently dissolved in the alkali developer.

The protective film forming material of the present invention may further contain a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) as an optional component.
Since a wide variety of components (D) have already been proposed, any known one may be used. For example, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, monoalkylamines such as n-decylamine; dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, Tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n- Trialkylamines such as dodecylamine; diethanolamine, trieta Ruamin, diisopropanolamine, triisopropanolamine, di -n- octanol amine, alkyl alcohol amines tri -n- octanol amine is Ageraru. Among these, a secondary aliphatic amine and a tertiary aliphatic amine are particularly preferable, a trialkylamine having 5 to 10 carbon atoms is more preferable, and tri-n-octylamine is most preferable.
These may be used alone or in combination of two or more.
(D) It is preferable that a component is used in 0.01-5.0 mass parts with respect to 100 mass parts of (A1) component.

In addition, the protective film-forming material of the present invention may further contain an organic carboxylic acid or phosphorus oxo acid or a derivative thereof (E) (hereinafter referred to as (E) component) as an optional component. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
The component (E) is preferably used at a ratio of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A1).

  The protective film-forming material of the present invention may further contain miscible additives as desired, for example, additional resins for improving the performance of the protective film, surfactants for improving the coating properties, plasticizers, and stability. A coloring agent, a coloring agent, an antihalation agent, a dye, and the like can be appropriately added and contained.

The material for forming a protective film of the present invention is suitable for immersion exposure. Immersion lithography (Liquid Immersion Lithography) is one technology that is currently attracting attention (eg, Journal of Vacuum Science & Technology B (USA), 1999). Vol. 17, No. 6, 3306-3309. Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, pp. 2353-2356, Proceedings of (See Proceedings of SPIE (USA) 2002, 4691, 459-465, etc.). This method uses a solvent (liquid) having a refractive index larger than the refractive index of air in a portion between a lens and a resist layer on the wafer, which is conventionally filled with an inert gas such as air or nitrogen, during exposure. In this method, exposure (immersion exposure) is performed in a state filled with an immersion medium. According to such immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the focus can be reduced. It is said that there is no decrease in depth. Moreover, immersion exposure can be performed using an existing exposure apparatus. For this reason, immersion exposure is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention. Currently, water is mainly studied as an immersion medium for immersion exposure.
However, it is expected that various problems occur when the immersion medium comes into contact with the resist film. For example, the components in the resist layer are eluted from the resist layer into the immersion medium, the resist layer is altered and its performance is degraded, or the refractive index of the immersion medium is locally changed by the eluted components. The eluted components may adversely affect the formation of the resist pattern due to contamination of the lens surface of the exposure apparatus. That is, problems such as deterioration in sensitivity, a resulting resist pattern having a T-top shape, and surface roughness and swelling of the resist pattern are expected.
On the other hand, since the protective film forming material of the present invention can form a protective film having a high substance blocking property against the permeation of substances, the influence of the resist layer on the immersion medium and the influence of the immersion medium on the resist layer are suppressed. It is suitable for immersion exposure.

≪Laminated body≫
Next, the laminated body of this invention is demonstrated.
The laminate of the present invention comprises, on a substrate, a resist layer containing a base material component (A ′) whose alkali solubility is changed by the action of an acid and an acid generator component (B ′) that generates an acid upon exposure; The protective film made of the protective film forming material of the present invention is laminated in order.

The protective film can be formed by applying the protective film-forming material of the present invention on the resist layer, as shown in a “resist pattern forming method” described later.
The thickness of the protective film is not particularly limited, and is appropriately set according to the substance blocking property required for the protective film. In the present invention, the preferable upper limit value of the thickness of the protective film is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less in consideration of performing exposure of the resist layer through the protective film. If the thickness of the protective film is 100 nm or less, the resist layer can be exposed without any problem even if the protective film is interposed. The lower limit value of the thickness of the protective film is preferably 15 nm or more, and more preferably 20 nm or more. When the thickness is 15 nm or more, the effect of the present invention is sufficient.

The substrate is not particularly limited, and a conventionally known substrate can be used. For example, a substrate for an electronic component or a substrate on which a predetermined wiring pattern is formed can be exemplified.
More specifically, examples of the substrate include a silicon wafer, a metal substrate such as copper, chromium, iron, and aluminum, and a glass substrate.
As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.

The resist layer is referred to as a base material component (A ′) (hereinafter also referred to as (A ′) component) and an acid generator component (B ′) (hereinafter referred to as (B ′) component) that generates an acid upon exposure. And a so-called chemically amplified resist composition.
The (A ′) component in the resist layer is not particularly limited. For example, one or more alkali-soluble resins or resins that can be alkali-soluble, which are conventionally used as a base component for chemically amplified resists, are used. can do. In the former case, a so-called negative type resist composition is used, and in the latter case, a so-called positive type resist composition.
In the case of the negative type, a crosslinking agent component (C ′) (hereinafter sometimes referred to as (C ′) component) is blended with the (B ′) component in the resist composition. When an acid is generated from the component (B ′) by exposure during the formation of the resist pattern, the acid acts, and crosslinking occurs between the component (A ′) and the component (C ′), resulting in alkali insolubility. Examples of the component (C ′) include the same components as the component (C).
In the case of the positive type, the component (A ′) is an alkali-insoluble one having a so-called acid dissociable dissolution inhibiting group, and when acid is generated from the component (B ′) by exposure, the acid is inhibited by the acid dissociable dissolution. By dissociating the group, the component (A ′) becomes alkali-soluble.
Examples of the component (B ′) include the same components as the component (B).
Moreover, the resist layer may have components other than the above, for example, the (D) component, the (E) component, and the like.

  An organic or inorganic antireflection film may be provided between the substrate and the resist layer.

≪Resist pattern formation method≫
The resist pattern forming method of the present invention can be performed, for example, as follows.
First, a resist composition is applied onto a substrate such as a silicon wafer with a spinner or the like, and prebaking is performed at a temperature of, for example, 80 to 150 ° C., preferably 110 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. To form a resist layer.
Next, the protective film forming material of the present invention is applied onto the resist layer with a spinner or the like, and soft baking is performed, for example, at a temperature of 40 to 100 ° C. for 15 to 120 seconds to form a protective film. The laminated body of this invention is created. Soft baking is not always necessary, and soft baking is not necessary when a good coating film with excellent uniformity can be obtained only by coating.
Next, after selectively exposing the resist layer through a desired mask pattern through the protective film, PEB (post-exposure heating) is performed at a temperature of 80 to 150 ° C. for 40 to 120 seconds, for example. Preferably, it is applied for 60 to 90 seconds.
After the exposure, the protective film is removed and the resist layer is developed using an alkaline developer, for example, a 0.1 to 10% by mass tetramethylammonium hydroxide aqueous solution. In the present invention, since the protective film is dissolved in an alkaline developer, the protective film can be removed and the resist layer can be developed in the same process.
By these steps, a resist pattern is formed on the substrate.
An organic or inorganic antireflection film can be provided between the substrate and the resist layer.

The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. In particular, the resist composition according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

When immersion exposure is performed using the protective film-forming material of the present invention, for example, the laminate obtained in the same manner as described above is selectively subjected to immersion exposure via a desired mask pattern. At this time, the space between the protective film and the lens at the lowest position of the exposure apparatus is previously filled with a solvent (immersion medium) having a refractive index larger than that of air.
At this time, the immersion medium is more preferably a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist layer.
Examples of the solvent having a refractive index larger than that of air and smaller than the refractive index of the resist layer used include water, silicon-based inert liquid, and fluorine-based inert liquid.
Specific examples of the fluorine-based inert liquid include fluorine-based compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. The boiling point of the liquid or perfluoroalkyl compound is 70 to 180 ° C., and more preferably, the boiling point is 80 to 160 ° C. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound. Examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine (boiling point: 174 ° C.). Among these fluorinated inert liquids, those having a boiling point in the above range are preferable because the medium used for immersion exposure can be removed by a simple method after the exposure is completed.
In the present invention, water is particularly preferably used as the immersion medium because it is not easily adversely affected by water and is excellent in sensitivity and resist pattern profile shape. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

As described above, the protective film forming material of the present invention has a high density of the protective film to be formed, and therefore has excellent substance blocking properties. Therefore, by providing the protective film on the resist layer, the environmental influence can be reduced, and problems such as a decrease in sensitivity, a deterioration in pattern shape, and a decrease in resolution due to the environmental influence can be improved. That is, since the organic alkali (basic compound) such as N-methyl-2-pyrrolidone, ammonia, pyridine, and triethylamine is usually present in the environment such as a semiconductor production line, the surface of the chemically amplified resist layer Then, an acid shortage occurs due to the action of the basic compound, and the above-mentioned problem occurs. For example, in the case of a positive resist composition, the cross-sectional shape may be a T-top shape or may be connected to an adjacent resist pattern. In the case of a negative resist composition, the top of the resist pattern tends to be rounded.
On the other hand, in the present invention, the protective film made of the protective film-forming material of the present invention has excellent substance blocking properties. Therefore, by providing the protective film on the resist layer, for example, after applying the resist In addition, it is possible to prevent contamination of the basic compound to the resist layer during the time from the provision of the protective film to the exposure, the time from the exposure to the post-exposure heating (PEB), etc. Environmental impact is reduced.

  Further, since the protective film made of the material for forming a protective film of the present invention can be removed with an alkaline developer, the protective film can be removed and the resist layer can be developed in the same process, and the resist pattern can be easily formed. In addition, it can be performed at a low cost in a short time.

  Furthermore, the protective film-forming material, laminate and resist pattern forming method of the present invention are suitable for immersion exposure. That is, in the immersion exposure, as described above, since the immersion solvent contacts the resist layer, the resist layer changes in quality, or a component that adversely affects the solvent from the resist elutes and the refractive index of the solvent. It is considered that the original advantage of the immersion exposure is impaired due to the phenomenon such as change in the thickness. On the other hand, in the present invention, since the protective film having excellent substance blocking properties is provided between the immersion medium and the resist layer, those phenomena can be prevented.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
In the synthesis examples, the following monomers were used.
NBHFAA: norbornene hexafluoroalcohol acrylate AdOHA represented by the following chemical formula (i): adamantanol acrylate RHMA-E represented by the following chemical formula (ii): (α-hydroxymethyl) ethyl represented by the following chemical formula (iii) Acrylate RHMA-M: (α-hydroxymethyl) methyl acrylate represented by the following chemical formula (iv)

Synthesis example 1
13.3 g of NBHFAA, 3.51 g of RHMA-E and 6.0 g of AdOHA, and 0.7 g of dimethyl azobisisoacetate as a polymerization initiator were dissolved in 200 ml of THF (tetrahydrofuran). Nitrogen bubbling was performed for about 10 minutes, and the mixture was stirred for 4 hours while heating using an oil bath at 70 ° C., and then cooled to room temperature. Next, after concentrating the reaction solution with an evaporator, the concentrated solution was dissolved in 120 ml of THF, and poured into 1000 ml of heptane to precipitate the resin, followed by filtration. The obtained resin was dried in a dryer at 40 ° C. for 24 hours to obtain 21.0 g of a white solid.
The chemical formula of the obtained resin is the following chemical formula (I). Its mass average molecular weight (Mw) was 5570 and dispersity (Mw / Mn) was 2.02. When confirmed by carbon NMR, the composition ratio (mol%) was 1 / m / n = 42/29/29. This is Resin 1.

Synthesis example 2
NBHFAA 13.3 g, RHMA-M 3.13 g and AdOHA 6.0 g, and 0.7 g of azobisisoacetate dimethyl as a polymerization initiator were dissolved in 200 ml of THF. Nitrogen bubbling was performed for about 10 minutes, and the mixture was stirred for 4 hours while heating using an oil bath at 70 ° C., and then cooled to room temperature. Next, after concentrating the reaction solution with an evaporator, the concentrated solution was dissolved in 120 ml of THF, and poured into 1000 ml of heptane to precipitate the resin, followed by filtration. The obtained resin was dried in a dryer at 40 ° C. for 24 hours to obtain 14.9 g of a white solid.
The chemical formula of the obtained resin is the following chemical formula (II). Its mass average molecular weight (Mw) was 6300, and dispersity (Mw / Mn) was 1.83. When confirmed by carbon NMR, the composition ratio (mol%) was 1 / m / n = 42/29/29. This is Resin 2.

[Example 1] Normal (dry) exposure 100 parts by mass of the resin 1 synthesized in Synthesis Example 1 was dissolved in 3900 parts by mass of 2-methyl-1-propanol as an organic solvent, and the solid content concentration was 2.5% by mass. A protective film-forming material 1 was prepared.
Next, an organic antireflection film composition “ARC-29” (trade name, manufactured by Brewer Science) is applied onto a substrate (8-inch silicon wafer) on an 8-inch silicon wafer, By baking and drying on a hot plate at 225 ° C. for 60 seconds, an organic antireflection film having a thickness of 77 nm was formed. On the organic antireflection film, a chemically amplified positive resist composition “TArF-P6111” (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied and heated at 130 ° C. for 90 seconds to form a resist layer having a thickness of 225 nm. Formed. And the protective film formation material 1 was apply | coated using the spinner on the said resist layer, and the protective film with a film thickness of 70 nm was formed by heating at 90 degreeC for 60 second (s).
Next, an ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S302 (Nikon Corp .; NA (numerical aperture) = 0.60, 2/3 annular illumination). .
Then, PEB treatment at 130 ° C. for 90 seconds, paddle development with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, and then water rinsing with pure water for 30 seconds, followed by shaking off and drying. And a 1: 1 130 nm line and space (LS) pattern was formed. The sensitivity at that time was 18.0 mJ / cm ² and the resist pattern shape was also good.

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).

[Example 2] Simulated immersion exposure On an 8-inch silicon wafer, an organic antireflection film composition “ARC-29” (trade name, manufactured by Brewer Science) was used to form a substrate (8-inch silicon). An organic antireflective film having a film thickness of 77 nm was formed by coating on a hot plate and baking and drying on a hot plate at 225 ° C. for 60 seconds. On the organic antireflection film, a chemically amplified positive resist composition “TArF-P6111” (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied and heated at 130 ° C. for 90 seconds to form a resist layer having a thickness of 225 nm. Formed. And the protective film formation material 1 was apply | coated using the spinner on the said resist layer, and the protective film with a film thickness of 70 nm was formed by heating at 90 degreeC for 60 second (s).
Next, an ArF excimer laser (193 nm) was selectively irradiated through the mask pattern by an ArF exposure apparatus NSR-S302 (Nikon Corp .; NA (numerical aperture) = 0.60, 2/3 annular illumination). After that, pure water (immersion medium) was dropped for 60 seconds while rotating the substrate.
Then, PEB treatment at 130 ° C. for 90 seconds, paddle development with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, and then water rinsing with pure water for 30 seconds, followed by shaking off and drying. A 1: 1 130 nm LS pattern was formed. The sensitivity at that time was 18.0 mJ / cm ² .

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).

[Example 3] Immersion exposure An organic antireflective coating composition “ARC-29” (trade name, manufactured by Brewer Science Co., Ltd.) on an 8-inch silicon wafer using a spinner (8-inch silicon wafer) The organic antireflection film having a film thickness of 77 nm was formed by applying the film onto the hot plate and baking and drying on a hot plate at 225 ° C. for 60 seconds. On the organic antireflection film, a chemically amplified positive resist composition “TArF-P6111” (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied and heated at 130 ° C. for 90 seconds to form a resist layer having a thickness of 225 nm. Formed. And the protective film formation material 1 was apply | coated using the spinner on the said resist layer, and the protective film with a film thickness of 96 nm was formed by heating at 90 degreeC for 60 second.
Next, as immersion exposure, a two-beam interference exposure machine LEIES193-1 (made by Nikon) is used to perform immersion two-beam interference exposure by prism, water (immersion medium) and two beam interferences of 193 nm. It was. A similar method is also disclosed in “Journal of Vacuum Science & Technology B” (USA), 2001, Vol. 19, No. 6, pp. 2353-2356. It is known as a method for easily obtaining a resist pattern.
Then, PEB treatment is performed at 130 ° C. for 90 seconds, paddle development is further performed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, and then water rinsing is performed using pure water for 30 seconds. By shaking off and drying, a 1: 1 65 nm LS pattern was formed. The sensitivity at that time was 9.7 mJ / cm ² .

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).
By providing a protective film on the resist layer, a fine resist pattern could be formed without being affected by the immersion medium.

[Example 4] Normal (dry) exposure After preparing protective film forming material 2 in the same manner as in Example 1 except that resin 1 was replaced with resin 2, a resist pattern was formed in the same manner as in Example 1. Formed.
As a result, a 1: 1 130 nm LS pattern was formed. The sensitivity at that time was 18.0 mJ / cm ² and the resist pattern shape was also good.

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).

[Example 5] Simulated immersion exposure A resist pattern was formed in the same manner as in Example 2 except that the protective film-forming material 1 was replaced with the protective film-forming material 2. As a result, a 1: 1 130 nm LS pattern was formed. The sensitivity at that time was 18.0 mJ / cm ² .

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).

[Example 6] Immersion exposure A resist pattern was formed in the same manner as in Example 3 except that the protective film-forming material 1 was replaced with the protective film-forming material 2. As a result, a 1: 1 65 nm LS pattern was formed. The sensitivity at that time was 9.7 mJ / cm ² .

When the protective film was formed, no mixing between the protective film and the lower resist layer was observed.
The protective film was completely removed by development using an alkaline developer (2.38 mass% tetramethylammonium hydroxide aqueous solution).
By providing a protective film on the resist layer, a fine resist pattern could be formed without being affected by the immersion medium.

Claims (13)

  A structural unit derived from acrylic acid and having no cyclic structure, the structural unit (a0-1) having an alcoholic hydroxyl group in the side chain, and an alicyclic group having a fluorinated hydroxyalkyl group A protective film-forming material that can be removed with an alkali developer for a resist layer, which is obtained by dissolving an alkali-soluble resin (A1) containing a structural unit (a1) contained in an organic solvent. The structural unit (a0-1) is represented by the following general formula (3).

[Wherein, R ¹ is a hydrogen atom, an alkyl group, a fluorinated alkyl group, a fluorine atom or a hydroxyalkyl group, R ² is a hydrogen atom, an alkyl group or a hydroxyalkyl group, and at least ^one of R ¹ and R ² One is a hydroxyalkyl group. ]
The protective film-forming material according to claim 1, which is a structural unit represented by the formula:   The structural unit (a0-1) includes a structural unit derived from an (α-hydroxyalkyl) acrylic acid alkyl ester and / or a structural unit derived from an (α-alkyl) acrylic acid hydroxyalkyl ester. Or the protective film-forming material according to 2.   The proportion of the structural unit (a0-1) in the alkali-soluble resin (A1) is 10 to 80 mol% with respect to the total of all the structural units constituting the alkali-soluble resin (A1). The material for forming a protective film according to any one of the above. The structural unit (a1) is represented by the following general formula (1)

[Wherein, R represents a hydrogen atom, an alkyl group, a fluorinated alkyl group or a fluorine atom, and m, n and p are each independently an integer of 1 to 5. ]
The protective film-forming material according to claim 1, which is a structural unit represented by the formula:   The ratio of said structural unit (a1) in said alkali-soluble resin (A1) is 10-80 mol% with respect to the sum total of all the structural units which comprise alkali-soluble resin (A1), Any one of Claims 1-5 The protective film forming material according to claim 1.   The protective film-forming material according to any one of claims 1 to 6, comprising a structural unit (a0-2) derived from an acrylate ester and containing a hydroxyl group-containing alicyclic group. The structural unit (a0-2) is represented by the following general formula (2)

[Wherein, R represents a hydrogen atom, an alkyl group, a fluorinated alkyl group or a fluorine atom, and q represents an integer of 1 to 3. ]
The material for forming a protective film according to claim 6, wherein the material is a structural unit represented by:   The material for forming a protective film according to claim 1, wherein the alkali-soluble resin (A1) has a mass average molecular weight in the range of 2000 to 30000.   The protective film-forming material according to any one of claims 1 to 9, wherein the organic solvent contains at least one selected from the group consisting of alcohols having 4 to 6 carbon atoms.   The material for forming a protective film according to any one of claims 1 to 10, which is for immersion exposure.   A resist layer containing a base material component (A ') whose alkali solubility is changed by the action of an acid and an acid generator component (B') which generates an acid upon exposure on the substrate, and any one of claims 1 to 11 A laminate in which the protective film made of the protective film-forming material according to claim 1 is laminated in order. After forming a resist layer on the substrate, a protective film is formed on the resist layer using the protective film-forming material according to any one of claims 1 to 11, and the resist is interposed through the protective film. A resist pattern forming method for forming a resist pattern by selectively exposing a layer, performing PEB (post-exposure heating), and then removing the protective film and developing the resist layer with an alkaline developer.