JP4545524B2 - Laminated body and resist pattern forming method - Google Patents

Description

  The present invention relates to a protective film forming material for a resist layer used in electron beam or EUV lithography, a laminate using the protective film forming material, and a resist pattern forming method.

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, pattern miniaturization has been rapidly progressing due to advances in lithography technology.
As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but at present, mass production of semiconductor elements using a KrF excimer laser or an ArF excimer laser has started. Furthermore, recently, EUV (Extreme Ultraviolet (extreme ultraviolet light); wavelength of about 13.5 nm) lithography and electron beam lithography have attracted attention (for example, see Non-Patent Document 1). In particular, since electron beam lithography can form a pattern without using a mask that requires a large amount of money for its production, it is used in small-scale production with a negligible throughput, research and development of a new semiconductor structure, and the like.

On the other hand, 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.
Currently, resins are mainly used as the base component of chemically amplified resists. For example, in the case of the positive type, some of the hydroxyl groups of polyhydroxystyrene resins and carboxy groups of (meth) acrylic resins are acid-dissociated. Those protected with a soluble dissolution inhibiting group are used (see, for example, Patent Documents 1 and 2). Recently, it has been proposed to use a low molecular weight material having an alkali-soluble group such as a hydroxyl group and partially or entirely protected with an acid dissociable, dissolution inhibiting group (see, for example, Non-Patent Document 2). .

However, when a chemically amplified resist is used, there is a problem that problems such as a decrease in sensitivity, a deterioration in the shape of the resist pattern, and a decrease in resolution occur particularly in lithography using an electron beam or EUV.
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. In particular, in lithography using an electron beam or EUV, since exposure is usually performed in a reduced pressure environment, it is necessary to perform a reduced pressure operation, a purge operation, or the like, so that the process delay is long and the environmental influence becomes a serious problem.

To industrially mass-produce this problem, mounting equipment such as coating equipment, exposure equipment, and development equipment is housed in a clean room and a chemical filter is provided, or all mounting equipment is inlined or inlined. Such measures are taken such as providing individual chemical filters on the mounted equipment.
JP-A-5-249682 Japanese Patent No. 2881969 J. et al. Photopolym. Sci. Technol. 17 (2004) 435-440 J. et al. Photopolym. Sci. Technol. Vol. 17 (2004) 367-372

  However, enormous investment is required in order to cope with such environmental impacts, so it is difficult to carry out the above-described measures in small-scale production and research and development. Therefore, the resist used in these cases is currently limited to non-chemically amplified resists that are not affected by the environment. However, the non-chemically amplified resist is significantly less sensitive than the chemically amplified resist and is not suitable for lithography using an electron beam or EUV.

  The present invention has been made to solve the above-described problems, and is a protective film-forming material, a laminate, and a resist that can reduce environmental impact on a chemically amplified resist layer used in electron beam or EUV lithography An object is to provide a pattern forming method.

［式中、Ｒ ^１ 〜Ｒ ^６ はそれぞれ独立に炭素数１〜１０のアルキル基または芳香族炭化水素基であって、その構造中にヘテロ原子を含んでもよく；ｇ、ｊはそれぞれ独立に１以上の整数であり、ｋは０または１以上の整数であり、かつｇ＋ｊ＋ｋが５以下であり；ｈは１以上の整数であり、ｌ、ｍはそれぞれ独立に０または１以上の整数であり、かつｈ＋ｌ＋ｍが４以下であり；ｉは１以上の整数であり、ｎ、ｏはそれぞれ独立に０または１以上の整数であり、かつｉ＋ｎ＋ｏが４以下であり；ｐは１である。］
で表される化合物である積層体である。
本発明の第二の態様は、基板上に、第一の態様の積層体を形成し、前記保護膜を介して前記レジスト層を電子線またはＥＵＶにより選択的に露光し、ＰＥＢ（露光後加熱）を施した後、前記保護膜を除去し、前記レジスト層を現像してレジストパターンを形成するレジストパターン形成方法である。
As a result of intensive studies, the present inventors have found that the above problem can be solved by providing a protective film containing a fluorine-containing polymer on the resist layer, and have completed the present invention.
That is, according to the first aspect of the present invention, a resist layer containing a base material component (A) and an acid generator component (B) that generates an acid upon exposure and a fluorine-containing polymer (F) are organically formed on a substrate. A laminate in which a protective film made of a protective film-forming material dissolved in a solvent is sequentially laminated, wherein the base material component (A) has two or more phenolic hydroxyl groups and a molecular weight of 300. Containing a protector (X1) in which a part of the phenolic hydroxyl group in the polyhydric phenol compound (x) of ˜2500 is protected with an acid dissociable, dissolution inhibiting group, and the polyhydric phenol compound (x) The following general formula (I)

[Wherein, R ^{1 to} R ⁶ are each independently an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group, and the structure thereof may include a hetero atom; g and j are each independently 1 And k is an integer of 0 or 1 and g + j + k is 5 or less; h is an integer of 1 or more, and l and m are each independently 0 or an integer of 1 or more; And h + 1 + m is 4 or less; i is an integer of 1 or more, n and o are each independently 0 or an integer of 1 or more, and i + n + o is 4 or less; p is 1. ]
In a compound der Ru laminate represented.
In the second aspect of the present invention, the laminate of the first aspect is formed on a substrate, the resist layer is selectively exposed with an electron beam or EUV through the protective film, and PEB (post-exposure heating) is formed. ), The protective film is removed, and the resist layer is developed to form a resist pattern.

  In the present invention, “exposure” is a concept including general irradiation of radiation.

  INDUSTRIAL APPLICABILITY According to the present invention, there are provided a protective film forming material, a laminate, and a resist pattern forming method capable of reducing the environmental influence on a chemically amplified resist layer used for electron beam or EUV lithography.

Hereinafter, the present invention will be described in more detail.
≪Material for protective film formation≫
The material for forming a protective film of the present invention is obtained by dissolving a fluorine-containing polymer (F) (hereinafter sometimes referred to as component (F)) in an organic solvent.

The component (F) is not particularly limited as long as it can form a film and contains a fluorine atom in its structure. More specifically, the component (F) is obtained by polymerizing a compound having an unsaturated bond and having an alkyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms (hereinafter referred to as a fluoroalkyl compound). Resin, for example, fluoroalkyl polyether and the like.
Examples of the fluoroalkyl compound include a cyclic fluoroalkyl compound in which the alkyl group includes a ring structure, and a chain fluoroalkyl compound in which the alkyl group is linear or branched. As the cyclic fluoroalkyl compound, the alkyl group preferably has 3 to 15 carbon atoms, and more preferably 4 to 10 carbon atoms. As the chain-type fluoroalkyl compound, the alkyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 10 carbon atoms.
Further, the fluoroalkyl compound is preferably a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms.

  Among these, it is particularly preferable that the component (F) contains the cyclic perfluoroalkyl polyether (F1) and the chain perfluoroalkyl polyether (F2). In this case, the protective film made of the material for forming a protective film of the present invention has excellent gas shielding properties and is excellent in the effect of reducing environmental impact. Further, the protective film can be made thinner (for example, a film thickness of 40 nm or less). Moreover, since it has a film quality with an appropriate hardness and can be easily removed with a solvent, it is highly useful as a protective film. Furthermore, it has an effect of reducing standing waves and also has a function as an antireflection film.

  Examples of the cyclic perfluoroalkyl polyether (F1) include a polymer having a structural unit represented by the following general formula (f11) and / or a structural unit represented by the following formula (f12).

（式中、ａ、ｂはそれぞれ独立して０又は１〜３の整数であり；ｃは１〜３の整数である）

(Wherein, a and b are each independently an integer of 0 or 1 to 3; c is an integer of 1 to 3)

A polymer having a structural unit represented by the formula (f11) is commercially available, for example, as “Cytop” (trade name) (manufactured by Asahi Glass Co., Ltd.).
Polymers having a structural unit represented by the formula (f12) are commercially available as “Teflon (registered trademark) AF1600”, “Teflon (registered trademark) AF2400” (trade name) (all of which are manufactured by DuPont). Yes.

  Examples of the chain perfluoroalkyl polyether (F2) include a polymer represented by the following general formula (f21).

（式中、Ｒ^１、Ｒ^２は炭素原子数１〜６のパーフルオロアルキル基であり；ｍは１〜５の整数であり；ｎは１〜１０の整数である）

(Wherein R ¹ and R ² are perfluoroalkyl groups having 1 to 6 carbon atoms; m is an integer of 1 to 5; n is an integer of 1 to 10)

  The polymer having the structural unit represented by the formula (f21) is “DEMNUM S-20”, “DEMNUM S-65”, “DEMNUM S-100”, “DEMNUM S-200” (trade name) (above, any Is also commercially available as Daikin Industries, Ltd.). Among these, “DEMNUM S-20” is preferably used.

In the component (F), the total amount of the cyclic perfluoroalkyl polyether (F1) and the chain perfluoroalkyl polyether (F2) is based on the total mass of the component (F) for the above effect. 50-100 mass% is preferable, 80-100 mass% is more preferable, and 100 mass% is the most preferable.
In the component (F), the ratio of the cyclic perfluoroalkyl polyether (F1) to the chain perfluoroalkyl polyether (F2) is preferably 3:10 to 10: 1 (mass ratio). 6:10 to 10: 2 is more preferable. If the ratio of the cyclic perfluoroalkyl polyether (F1) exceeds the above range, the removal property of the protective film may be deteriorated and the development of the resist layer may be hindered. On the other hand, when the ratio of the cyclic perfluoroalkyl polyether (F1) is less than the above range, the film quality of the protective film becomes soft, and when the laminate provided with the protective film is transported, the shape of the protective film There is a risk that the surroundings of the device may be contaminated due to collapse or dripping.

The organic solvent in the protective film-forming material of the present invention is not particularly limited as long as it can dissolve the component (F), but a fluorine-containing organic solvent is particularly preferable.
Specific examples of the fluorine-containing organic solvent include perfluoroalkanes such as perfluorohexane and perfluoroheptane; perfluorocycloalkanes such as perfluorocyclohexane and perfluorocycloheptane; part of perfluoroalkane or perfluorocycloalkane Perfluoroalkene or perfluorocycloalkene with a double bond remaining; perfluorocyclic ether such as perfluorotetrahydrofuran or perfluoro (2-butyltetrahydrofuran); perfluorotributylamine, perfluorotetrapentylamine, perfluorotetrahexyl Examples include perfluoroalkylamines such as amines. These may be used singly or in combination of two or more. Further, other organic solvents having compatibility and surfactants may be added as additives to improve the solubility.

The protective film-forming material of the present invention can be produced by dissolving the component (F) in an organic solvent.
In the protective film forming material, the concentration of the component (F) is preferably 1 to 10% by mass and more preferably 2 to 5% by mass with respect to the total mass of the protective film forming material in consideration of applicability and the like.

  The protective film-forming material of the present invention may contain various additives such as preservatives, stabilizers, surfactants and the like as long as the effects of the present invention are not impaired.

≪Laminated body≫
The laminate of the present invention is obtained by laminating a resist layer and a protective film made of the protective film-forming material of the present invention in order on a substrate.

<Protective film>
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 gas shielding property required for the protective film. In the present invention, the preferable upper limit value of the thickness of the protective film is preferably 40 nm or less, more preferably 35 nm or less, and further preferably 30 nm or less in consideration of exposure of the resist layer through the protective film. If the thickness of the protective film is 40 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.

<Board>
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.

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

<Resist layer>
The resist layer contains a base material component (A) (hereinafter also referred to as (A) component) and an acid generator component (B) (hereinafter also referred to as (B) component) that generates an acid upon exposure. And a so-called chemically amplified resist composition.

As the resist composition, those proposed as resist materials suitable for electron beam or EUV lithography can be used.
As such a resist composition, for example, as component (A), one or two or more types of alkali-soluble resins or resins that can be alkali-soluble, which are usually used as base resins for chemically amplified resists, are used. The resist composition which has been used. 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 present invention, the resist layer preferably has positive radiation sensitivity.

  In the case of the negative type, a crosslinking agent is blended in the resist layer together with the components (A) and (B). And when an acid generate | occur | produces from (B) component by exposure, this acid will act and bridge | crosslinking will occur between (A) component and a crosslinking agent, and will become alkali-insoluble. As the crosslinking agent, for example, an amino crosslinking agent such as melamine, urea or glycoluril having a methylol group or alkoxymethyl group is usually used.

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 converted into the acid dissociable dissolution inhibiting group. (A) component becomes alkali-soluble by dissociating.
Therefore, if exposure is performed through a mask pattern in the formation of a resist pattern, or if post-exposure heating (PEB) is performed in addition to exposure, the exposed area turns into alkali-soluble while the unexposed area remains insoluble in alkali. A positive resist pattern can be formed by alkali development.

Component (A) Component (A) is not particularly limited, and any of those proposed as a base component of a chemically amplified resist, for example, a resin in which a part of hydroxyl groups of polyhydroxystyrene is protected with an alkoxyalkyl group Alternatively, a resin in which a carboxyl group of (meth) acrylic acid and a tertiary ester are formed can be used.
In the present invention, in particular, since the roughness is reduced and a resist pattern excellent in pattern shape and resolution can be formed, the component (A) has two or more phenolic hydroxyl groups and has a molecular weight of 300 to 2500. The polyphenolic compound (x) preferably contains a protected body (X1) in which a part of the phenolic hydroxyl group is protected with an acid dissociable, dissolution inhibiting group.

Here, the polyphenol compound (x) is the one before being protected with the acid dissociable dissolution inhibiting group, the one protected with the acid dissociable dissolution inhibiting group is the protector (X1), and (A ) Component contains a protector (X1).
In the protector (X1), when an acid generated from the component (B) is acted upon by exposure, the acid dissociable, dissolution inhibiting group is dissociated, thereby increasing alkali solubility. Therefore, in the formation of the resist pattern, when the resist layer containing the protector (X1) is selectively exposed or heated after the exposure in addition to the exposure, the exposed portion turns into alkali-soluble while the unexposed portion becomes alkaline. Since it remains insoluble and does not change, a positive resist pattern can be formed by alkali development.

The polyhydric phenol compound (x) constituting the protector (X1) is not particularly limited as long as it is a polyhydric phenol compound having two or more phenolic hydroxyl groups and having a molecular weight of 300 to 2500. Polyhydric phenol compounds known as sensitizers and heat resistance improvers for chemically amplified g-line and i-line resists can be used. Examples of such polyhydric phenol compounds include the following.
Bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,3,4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl)- 4-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis ( 4-hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3-methylphenyl) Enyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3-methylphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -2-hydroxyphenylmethane Bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -3,4-dihydroxyphenylmethane, bis (4 -Hydroxy-3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,3,5-trimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,3,5) -Trimethylphenyl) -3-hydroxyphenylmethane, bis ( -Hydroxy-2,3,5-trimethylphenyl) -4-hydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene , Tetranuclear form of a formalin condensate of phenols such as phenol, m-cresol, p-cresol or xylenol.

  In the present invention, a polyhydric phenol compound represented by the following general formula (I) is particularly preferable because it is excellent in the effects of the present invention.

In the above formula, R ^{1 to} R ⁶ are each independently a linear, branched or cyclic lower alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, a cyclic alkyl group having 5 to 6 carbon atoms, or an aromatic group. Group hydrocarbon group. The alkyl group or aromatic hydrocarbon group may contain a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom in the structure. Examples of the aromatic hydrocarbon group include a phenyl group, a tolyl group, a xylyl group, a mesityl group, a phenethyl group, and a naphthyl group.
g and j are each independently an integer of 1 or more, preferably 1 or 2, k is 0 or 1 or more, preferably an integer not exceeding 2, and g + j + k is 5 or less.
h is an integer of 1 or more, preferably 1 to 2, l and m are each independently 0 or 1 or more, preferably an integer not exceeding 2, and h + 1 + m is 4 or less.
i is an integer of 1 or more, preferably 1 to 2, n and o are each independently 0 or 1 or more, preferably an integer not exceeding 2, and i + n + o is 4 or less.
p is 0 or 1, preferably 1.
Among these, those in which R ¹ is a cycloalkyl group, j is 1, R ² is a lower alkyl group, k is 1 and g is 1 are preferable.
Further preferably, R ¹ is a cyclohexyl group, the number of j is 1, and R ² is a lower alkyl group, the number of k is 1, the number of g is 1, and l, m and n A compound in which 0 and o are 0 and h and i are both 1 is preferable because a fine pattern can be formed with high resolution with reduced roughness.

  Among the polyhydric phenol compounds represented by the general formula (I), the most preferable one is a polyhydric phenol compound represented by the following formula (II) or (III).

  In the present invention, the polyphenol compound (x) needs to have a molecular weight of 300 to 2500, preferably 450 to 1500, more preferably 500 to 1200. When the molecular weight is not more than the upper limit, roughness is reduced, the pattern shape is further improved, and resolution is also improved. Moreover, when it is at least the lower limit value, a resist pattern having a good profile shape can be formed.

In addition, the polyphenol compound (x) is preferable because the molecular weight dispersity (Mw / Mn) is 1.5 or less because the effects of the present invention are further excellent. This is presumably because the alkali solubility of each protected body and unprotected body becomes relatively uniform as the molecular weight distribution of the polyphenol compound (x) is narrower. The degree of dispersion is preferably as small as possible, more preferably 1.4 or less, and most preferably 1.3 or less. In addition, when the polyhydric phenol compound (x) used for the base material is one kind alone, the dispersity is 1.
The degree of dispersion is determined by synthesizing the polyphenol compound (x), which is the final target product, and then purifying and removing reaction by-products and impurities, or removing unnecessary molecular weight portions by known methods such as molecular weight fractionation. Can be adjusted.
The dispersity is determined by measuring Mw and Mn by a commonly used measuring method of mass average molecular weight (Mw) and number average molecular weight (Mn), for example, gel permeation chromatography. It can be calculated by obtaining.

The protector (X1) is protected by substituting part or all of the hydroxyl groups of the phenolic hydroxyl group of the polyhydric phenol compound (x) with an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group is not particularly limited, and is appropriately selected from among those proposed for hydroxystyrene resins, (meth) acrylic acid resins and the like used in chemically amplified resist compositions for KrF and ArF. It can be selected and used.
Specific examples include a chain alkoxyalkyl group, a tertiary alkyloxycarbonyl group, a tertiary alkyl group, a tertiary alkoxycarbonylalkyl group, and a cyclic ether group.

Examples of the chain alkoxyalkyl group include 1-ethoxyethyl group, 1-ethoxymethyl group, 1-methoxymethylethyl group, 1-methoxymethyl group, 1-isopropoxyethyl group, 1-methoxypropyl group, 1-ethoxypropyl group. Group, 1-n-butoxyethyl group and the like.
Examples of the tertiary alkyloxycarbonyl group include a tert-butyloxycarbonyl group and a tert-amyloxycarbonyl group.
The tertiary alkyl group includes an aliphatic polycyclic group such as a chain tertiary alkyl group such as a tert-butyl group and a tert-amyl group, a 2-methyl-adamantyl group, and a 2-ethyladamantyl group. And tertiary alkyl groups containing a group.
Examples of the tertiary alkoxycarbonylalkyl group include a tert-butyloxycarbonylmethyl group and a tert-amyloxycarbonylmethyl group.
Examples of the cyclic ether group include a tetrahydropyranyl group and a tetrahydrofuranyl group.
Among these, a chain alkoxyalkyl group is preferable because it is excellent in dissociation, can improve the uniformity of the protector (X1), and can improve roughness, and is preferably a 1-ethoxyethyl group or a 1-ethoxymethyl group. Is more preferable.

In addition, the protector (X1) includes a plurality of polyhydric phenol compounds (hereinafter sometimes referred to as isomers) having different numbers of phenolic hydroxyl groups protected by acid dissociable, dissolution inhibiting groups (protection number). The closer the number of protected isomers, the better the effect of the present invention.
The proportion of each isomer in the protected form (X1) can be measured by means such as reverse phase chromatography.

In the component (A), the proportion of the protector (X1) is preferably more than 40% by mass, more preferably more than 50% by mass, further preferably more than 80% by mass, and most preferably 100% by mass. It is.
The proportion of the protector (X1) in the component (A) can be measured by means such as reverse phase chromatography.

The protector (X1) is, for example, a method of protecting all or part of the phenolic hydroxyl group with an acid dissociable, dissolution inhibiting group by a known method with respect to one or more polyphenol compounds (x). Can be manufactured.
In the protected body (X1), the protection number of each isomer can be adjusted by the conditions of the method for protecting with the acid dissociable, dissolution inhibiting group.

The component (A) may contain an unprotected body (X2) in which the phenolic hydroxyl group in the polyhydric phenol compound (x) is not protected with an acid dissociable, dissolution inhibiting group.
The unprotected body (X2) is a polyhydric phenol compound (x) in which the hydroxyl group of the phenolic hydroxyl group of the polyhydric phenol compound (x) is not protected at all by the acid dissociable, dissolution inhibiting group.
In the component (A), the proportion of the unprotected body (X2) is preferably as small as possible, more preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 10% by mass or less. Preferably, it is 0% by mass. When the unprotected body (X2) is 60% by mass or less, roughness can be reduced when a pattern is formed. Also, the resolution is excellent.
The ratio of the unprotected body (X2) in the component (A) can be adjusted, for example, by removing the unprotected body (X2) by gel permeation chromatography (GPC).
(A) The ratio of the unprotected body (X2) in a component can be measured by means, such as reverse phase chromatography.

  In addition, the protection rate of the phenolic hydroxyl group in component (A), that is, protection with an acid dissociable, dissolution inhibiting group relative to the total amount of phenolic hydroxyl groups protected with acid dissociable, dissolution inhibiting groups and unprotected phenolic hydroxyl groups. The proportion of the phenolic hydroxyl group formed is preferably 5 to 50 mol%, more preferably 7 to 30 mol% in view of resolution and roughness reduction effect.

In the present invention, the component (A) may contain any resin component that has been proposed as a base material component of the chemically amplified resist layer (hereinafter sometimes referred to as component (A-2)).
As the component (A-2), a novolak resin, a hydroxystyrene resin, a copolymer resin containing a structural unit derived from hydroxystyrene and a structural unit derived from (meth) acrylic acid ester, or the like is preferably used. It is done.
In the present specification, the “constituent unit” means a monomer unit constituting the polymer.
The “hydroxystyrene-based resin” is a resin having a structural unit derived from hydroxystyrene and not having a structural unit derived from (meth) acrylic acid ester.
The “structural unit derived from hydroxystyrene” is a structural unit formed by cleavage of an ethylenic double bond of hydroxystyrene, and may hereinafter be referred to as a hydroxystyrene unit.
The “structural unit derived from (meth) acrylic acid ester” is a structural unit formed by cleavage of an ethylenic double bond of (meth) acrylic acid ester, and is hereinafter referred to as a (meth) acrylate structural unit. There is.
“(Meth) acrylic acid” refers to one or both of methacrylic acid and acrylic acid.

Although it does not specifically limit as (A-2) component, For example, the structural unit (for example, the following structural unit (a1)) which has a phenolic hydroxyl group, and the structural unit (for example, the following) which has an acid dissociable, dissolution inhibiting group. Examples thereof include a resin having a structural unit (a2) and / or a structural unit (a3)), and an alkali-insoluble structural unit (for example, the following structural unit (a4)) used as necessary.
The resin has increased alkali solubility by the action of acid. That is, the acid-dissociable, dissolution inhibiting group of the structural unit (a2) or the structural unit (a3) is dissociated by the action of the acid generated from the component (B) by exposure, and is initially insoluble in the alkali developer. In such a resin, the alkali solubility is increased. As a result, a chemically amplified positive pattern can be formed by exposure and development.

・ Structural unit (a1)
The structural unit (a1) is a structural unit having a phenolic hydroxyl group and is represented by the following general formula (IV).

（式中、Ｒは水素原子またはメチル基を示す。）

(In the formula, R represents a hydrogen atom or a methyl group.)

R is not particularly limited as long as it is a hydrogen atom or a methyl group.
The bonding position of the phenolic hydroxyl group (—OH) to the benzene ring is not particularly limited, but the position 4 (para position) described in the formula is preferred.

In the component (A-2), the proportion of the structural unit (a1) is preferably 40 to 80 mol% with respect to all the structural units constituting the component (A-2). By setting it to 40 mol% or more, solubility in an alkali developer can be improved, and an effect of improving the pattern shape can be obtained. By setting it to 80 mol% or less, a balance with other structural units can be achieved. Can do.
The proportion of the structural unit (a1) is more preferably 50 mol% or more, still more preferably 60 mol% or more as the lower limit, and more preferably 75 mol% or less as the upper limit.

・ Structural unit (a2)
The structural unit (a2) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (V).

（式中、Ｒは水素原子またはメチル基を示し、Ｘは酸解離性溶解抑制基を示す。）

(In the formula, R represents a hydrogen atom or a methyl group, and X represents an acid dissociable, dissolution inhibiting group.)

R is not particularly limited as long as it is a hydrogen atom or a methyl group.
The acid dissociable, dissolution inhibiting group X is a tertiary alkyl group having a tertiary carbon atom, and the tertiary carbon atom of the tertiary alkyl group is an ester group (—C (O) O—). And a cyclic acetal group such as a tetrahydropyranyl group, a tetrahydrofuranyl group, and the like, which are bonded to an acid separation-dissolving group.
In addition to the above, such an acid dissociable, dissolution inhibiting group X can be arbitrarily used from those proposed as acid dissociable, dissolution inhibiting groups in, for example, chemically amplified positive resist compositions.

  Examples of the structural unit (a2) include those described in the following general formula (VI).

In the formula, R is the same as above, and R ¹¹ , R ¹² , and R ¹³ are each independently a lower alkyl group (which may be linear or branched. Preferably, it has 1 to 5 carbon atoms.) It is. Alternatively, two of these may be bonded to form a monocyclic or polycyclic alicyclic group (the alicyclic group preferably has 5 to 12 carbon atoms). Alternatively, R ¹¹ and R ¹² are lower alkyl groups (which may be linear or branched, preferably have 1 to 5 carbon atoms), and R ¹³ is a monocyclic or polycyclic group (alicyclic ring). The number of carbons in the formula group may preferably be 5-12).

When the structural unit (a2) does not have an alicyclic group, as the structural unit (a2), for example, those in which R ¹¹ , R ¹² , and R ¹³ are all methyl groups are preferable.

  In the case where the structural unit (a2) has an alicyclic group, preferred examples of the structural unit (a2) having a monocyclic alicyclic group include those having a cyclopentyl group and a cyclohexyl group. .

  In the case where the structural unit (a2) has an alicyclic group, among the structural units (a2) having a polycyclic alicyclic group, preferred examples include the following general formulas (VII) and (VIII). The thing shown by is mentioned.

［式中、Ｒは上記と同じであり、Ｒ^１４は低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数が１〜５である。）］

[Wherein, R is the same as above, and R ¹⁴ is a lower alkyl group (which may be linear or branched, preferably has 1 to 5 carbon atoms)]

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６は、それぞれ独立に低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数が１〜５である。）］

[Wherein, R is the same as described above, and R ¹⁵ and R ¹⁶ are each independently a lower alkyl group (which may be linear or branched. Preferably, it has 1 to 5 carbon atoms)]

  In the component (A-2), the proportion of the structural unit (a2) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, based on all structural units constituting the component (A-2). More preferred is ~ 35 mol%.

..Structural unit (a3)
The structural unit (a3) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (IX).

（式中、Ｒは水素原子またはメチル基を示し、Ｘ’は酸解離性溶解抑制基を示す。）

(In the formula, R represents a hydrogen atom or a methyl group, and X ′ represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X ′ is a tertiary alkyloxycarbonyl group such as a tert-butyloxycarbonyl group or a tert-amyloxycarbonyl group; a tert-butyloxycarbonylmethyl group or a tert-butyloxycarbonylethyl group. Tertiary alkyloxycarbonylalkyl groups such as; tertiary alkyl groups such as tert-butyl and tert-amyl groups; cyclic acetal groups such as tetrahydropyranyl and tetrahydrofuranyl groups; ethoxyethyl groups and methoxypropyl groups And the like.
Of these, a tert-butyloxycarbonyl group, a tert-butyloxycarbonylmethyl group, a tert-butyl group, a tetrahydropyranyl group, and an ethoxyethyl group are preferable.
In addition to the above, the acid dissociable, dissolution inhibiting group X ′ can be arbitrarily used from those proposed as acid dissociable, dissolution inhibiting groups in, for example, chemically amplified positive resist compositions.
In general formula (IX), the bonding position of the group (—OX ′) bonded to the benzene ring is not particularly limited, but the position 4 (para position) shown in the formula is preferable.

  In the component (A-2), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, based on all structural units constituting the component (A-2). More preferred is ~ 35 mol%.

..Structural unit (a4)
The structural unit (a4) is an alkali-insoluble structural unit and is represented by the following general formula (X).

（式中、Ｒは水素原子またはメチル基を示し、Ｒ^４は低級アルキル基を示し、ｎは０または１〜３の整数を示す。）

(In the formula, R represents a hydrogen atom or a methyl group, R ⁴ represents a lower alkyl group, and n represents 0 or an integer of 1 to 3).

The lower alkyl group for R ⁴ may be either linear or branched, and preferably has 1 to 5 carbon atoms.
n represents 0 or an integer of 1 to 3, and is particularly preferably 0.

  In the component (A-2), the proportion of the structural unit (a4) is preferably 1 to 40 mol% and more preferably 5 to 25 mol% with respect to all the structural units constituting the component (A-2). When the amount is 1 mol% or more, a resist pattern with less film loss and excellent shape can be obtained. When the amount is 40 mol% or less, balance with other structural units can be achieved.

  In the component (A-2), at least one structural unit selected from the group consisting of the structural unit (a1), the structural unit (a2), and the structural unit (a3) is essential, and the structure (a4) May be included. Moreover, the copolymer which has all these each structural units may be used individually by 1 type or in mixture of 2 or more types, and it is good also as a mixture of the polymers which have one or more of these structural units. Moreover, you may combine these.

  Moreover, although the component (A-2) can optionally contain structural units other than the structural units (a1), (a2), (a3), and (a4), these structural units (a1), ( The total ratio of a2), (a3), and (a4) is preferably 80 mol% or more, more preferably 90 mol% or more with respect to all structural units constituting the component (A-2). 100 mol% is most preferred.

In particular, an embodiment in which the following copolymer (1) or copolymer (2) is used alone or mixed is most preferable because an effect can be easily obtained. Moreover, it is preferable also from the point of heat resistance improvement.
(1) One type of copolymer (1) having the structural unit (a1) and the above (a3) or two or more types of different copolymers.
(2) One or more of the copolymers (2) having the structural unit (a1), the (a2), and the (a4), or two or more of different copolymers.
When mixing the copolymer (1) and the copolymer (2), the mixing ratio of the copolymer (1) and the copolymer (2) is, for example, 1/9 to 9/1 (mass ratio). Is preferable, and 3/7 to 7/3 is more preferable.

  The component (A-2) can be obtained by polymerizing a monomer for deriving each structural unit by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). it can.

The mass average molecular weight (Mw) of the component (A-2) (polystyrene conversion standard by gel permeation chromatography) is not particularly limited, but is preferably 2000 to 30000, more preferably 2000 to 20000, and 2500 to 12000. Is most preferred. If it is larger than this range, the solubility in a resist solvent is deteriorated, and if it is smaller, the dry etching resistance and the resist pattern cross-sectional shape may be deteriorated.
The dispersity (Mw / Mn) is preferably 1.0 to 5.0, and more preferably 1.0 to 3.0.

As the component (A), the protector (X1) and the component (A-2) may be used singly or in combination of two or more.
The content of the component (A) in the resist composition may be adjusted according to the film thickness of the resist layer to be formed.

Component (B) The component (B) can be used without particular limitation from known acid generators used in conventional chemically amplified resist compositions.
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.
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, tri (4 -Tert-bu Le) trifluoromethanesulfonate triphenylsulfonium, its like heptafluoropropane sulfonate or nonafluorobutane sulfonates.

  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 Pentenylacetonitrile, 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.

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, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

  In the present invention, it is particularly 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. If the amount is less than the above range, pattern formation may not be sufficiently performed, and if the amount exceeds the above range, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

Component (C) The resist composition can be produced by dissolving the component (A), the component (B), and any component described later in an organic solvent (hereinafter sometimes referred to as the component (C)).
As the component (C), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any one of conventionally known solvents for chemically amplified resists can be used. Two or more types 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 Polyhydric alcohols such as dipropylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof, cyclic ethers such as dioxane, Methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, pyruvate Le, methyl methoxypropionate, esters such as ethyl ethoxypropionate can be exemplified.
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 blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 9: 1 to 1: 9, more preferably 8: 2 to 2: 8. 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 8: 2 to 2: 8, more preferably 7: 3 to 3: 7.
In addition, as the component (C), 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.
Moreover, as (C) component, propylene glycol monomethyl ether (PGME) is also preferable.
The amount of the component (C) used is not particularly limited, and is a concentration that can be applied to a support such as a substrate, and is appropriately set according to the coating film thickness. It is used so that the partial concentration is in the range of 2 to 20% by mass, preferably 5 to 15% by mass.

Component (D) In order to improve the resist pattern shape, retention time stability, etc., the resist composition further contains a nitrogen-containing organic compound (D) (hereinafter referred to as component (D)) as an optional component. Can be made.
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) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

Component (E) In addition, for the purpose of preventing sensitivity deterioration due to the blending of the component (D) and improving the resist pattern shape, retention stability, etc., an organic carboxylic acid or phosphorus oxoacid or The derivative (E) (hereinafter referred to as component (E)) can be contained. 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.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

Other optional components In the resist composition, if desired, miscible additives such as an additional resin for improving the performance of the resist layer, a surfactant for improving the coating property, a dissolution inhibitor, A plasticizer, a stabilizer, a colorant, an antihalation agent, and the like can be appropriately added and contained.

The resist layer can be formed by applying the resist composition as described above on a substrate as shown in “Resist pattern formation method” below.
Although the thickness of a resist layer is not specifically limited, Preferably it is 50-300 nm, More preferably, it is 50-150 nm. By setting the thickness of the resist layer within this range, there is sufficient transparency to electron beams and EUV. Further, the resist pattern can be formed with high resolution, and sufficient resistance to dry etching can be obtained.

≪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, a resist layer is formed through a desired mask pattern in vacuum (for example, 1 × 10 ⁻⁷ to 1 × 10 ⁻⁵ Pa) or drawn by an electron beam or an EUV exposure apparatus through the protective film. After the selective exposure, PEB (post-exposure heating) is performed, for example, at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds.
After the exposure, the protective film is removed before the development process. This removal treatment can be performed, for example, by completely removing only the protective film by applying a solvent for dissolving and removing the protective film while rotating the silicon wafer with a spinner. As the solvent for removing the protective film, the above-described fluorine-containing organic solvent or an aqueous solution containing a surfactant can be used. In the present invention, it is particularly preferable to use a fluorine-containing organic solvent. The reason is that, after the protective film is dissolved and removed with a fluorine-containing organic solvent, the solution is recovered, distilled and purified to adjust the concentration, and can be reused as a protective film forming material. This is because the manufacturing cost can be reduced.
After removing the protective film, development processing is performed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. 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.

As described above, environmental effects can be reduced by the protective film forming material, the laminate, and the resist pattern forming method of the present invention. Therefore, it is possible to improve problems such as a decrease in sensitivity due to environmental influences, a deterioration in pattern shape, and a decrease in resolution. 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 gas shielding 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. This is because the protective film made of the protective film forming material of the present invention has excellent gas shielding properties.
In addition, the environmental influence after peeling of the protective film is not a problem because the reaction with the acid has already been completed.

Further, the protective film made of the material for forming a protective film of the present invention has high gas shielding properties, and has sufficient gas shielding properties to reduce environmental influence even when the film thickness is reduced. Therefore, it is suitable for electron beam or EUV lithography. That is, since the protective film can be thinned, the influence of the protective film upon exposure of the resist layer can be greatly reduced. In particular, in electron beam lithography, when a thick protective film is provided, electron beam scattering becomes a problem and resolution decreases, but in the present invention, electron beam scattering does not occur and the resolution is excellent, or Even if it occurs, even if the protective film is made thin enough to be ignored, it has sufficient gas shielding properties and can reduce environmental impact. Therefore, the present invention is particularly suitable for electron beam lithography.
It is known that a film is provided on a resist layer as an antireflection film for excimer laser. However, these are not intended to reduce the environmental impact, and it is unclear whether or not they have gas shielding properties to function as a protective film for reducing the environmental impact.
Further, according to the study of the present inventor, the antireflection film generally used conventionally has high gas permeability to function as a protective film, and it is necessary to form a thick film to prevent environmental influences. is there. In that case, in either case of electron beam or EUV, a thick film may affect the exposure, and there is a problem that the presence of the film causes deterioration of the resist pattern shape. In particular, in electron beam lithography, the influence of scattering by a thick film is significant.
On the other hand, in the present invention, it is possible to form a protective film having a high gas shielding property even with a thin film thickness, because the influence on exposure is small, and the problem of environmental influences can also be solved. Due to these synergistic effects, a resist pattern having a good shape can be obtained.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
[Production Example 1]
10 g of the polyhydric phenol compound represented by the above formula (II) (molecular weight 981: hereafter, abbreviated as MBSA) is dissolved in 33 g of tetrahydrofuran, and 1.8 g of ethyl vinyl ether is added thereto and stirred at room temperature for 12 hours. Reacted for hours. After completion of the reaction, extraction and purification were performed in a water / ethyl acetate system. This obtained 10.1 g of MBSA protectors (a1).
About the obtained MBSA protector (a1), the number of phenolic hydroxyl groups and the number of phenolic hydroxyl groups protected with 1-ethoxyethyl group in the MBSA protector (a1) were determined by 400 MHz proton NMR manufactured by JEOL. It was 19.9 mol% when it measured and the protection rate (mol%) was calculated | required. The protection rate is {number of phenolic hydroxyl groups protected with 1-ethoxyethyl group / (number of phenolic hydroxyl groups + 1 + number of phenolic hydroxyl groups protected with 1-ethoxyethyl group)} × 100.

[Example 1]
100 parts by mass of the MBSA protector (a1) obtained in Production Example 1, 10.0 parts by mass of triphenylsulfonium nonafluorobutane sulfonate, and 1.0 part by mass of tri-n-octylamine were combined with ethyl lactate ( EL) / propylene glycol monomethyl ether acetate (PM) = 4/6 (mass ratio) was dissolved in a mixed solvent to obtain a positive resist composition solution having a solid content concentration of 5 mass%.

  Also, a mixed resin consisting of demnum S-20 (manufactured by Daikin Industries) and CYTOP (manufactured by Asahi Glass Co., Ltd.) (mixing weight ratio = 1: 5) is dissolved in perfluorotributylamine, and the resin concentration is 2.5 wt%. A protective film forming material was obtained.

The positive resist composition solution obtained above was uniformly applied on an 8-inch silicon substrate subjected to hexamethyldisilazane treatment using a spinner, and baked (PAB) at 120 ° C. for 90 seconds. A resist layer (film thickness 150 nm) was formed.
Next, the protective film-forming material was uniformly applied on the resist layer at a rotational speed of 2000 using a spinner to form a protective film having a thickness of 30 nm, thereby obtaining a laminate.
Next, drawing (exposure) is performed on the resist layer of the obtained laminate with an electron beam drawing machine (LBX-5FE (manufactured by JEOL Co., Ltd., acceleration voltage 50 kV)) through a protective film to 110 ° C. 90 seconds baking (PEB).
Next, the protective film was dissolved and removed using perfluoro (2-butyltetrahydrofuran).
Next, the resist layer was developed with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) (23 ° C.) for 60 seconds, rinsed with pure water for 30 seconds, and line and space (L / S). A pattern was formed. The following evaluation was performed about the obtained resist pattern. The results are shown in Table 1.
<Sensitivity>
The exposure time during which a 100 nm line and space was formed at 1: 1 was measured in units of μC / cm ² (energy amount) as sensitivity (EOP).
<Pattern shape>
The cross-sectional shape of the 100 nm L / S pattern formed in the EOP was judged by SEM photographs.
<Resolution>
An L / S pattern was formed in the EOP, and its ultimate resolution (nm) was judged by SEM photographs.

[Comparative Example 1]
In Example 1, a protective pattern was not provided, and a resist pattern was formed and evaluated in the same manner as in Example 1 except that the PAB condition was changed to 110 ° C. and 90 seconds. The results are shown in Table 1.

As is clear from the above results, in Example 1 in which a protective film containing a fluorine-containing polymer was provided on the resist layer, a resist pattern with high sensitivity and excellent pattern shape and resolution was formed.
On the other hand, in Comparative Example 1 in which no protective film was provided, the sensitivity was low, the pattern shape was a T-top shape, and the resolution was also low.

Claims (4)

A protective film-forming material obtained by dissolving a resist layer containing a base component (A) and an acid generator component (B) that generates an acid upon exposure on a substrate, and a fluorine-containing polymer (F) in an organic solvent. A laminated body in which a protective film made of
The base component (A) has two or more phenolic hydroxyl groups and a part of the phenolic hydroxyl group in the polyphenol compound (x) having a molecular weight of 300 to 2500 is protected with an acid dissociable, dissolution inhibiting group. Containing the protected body (X1) ,
The polyhydric phenol compound (x) is represented by the following general formula (I)

[Wherein, R ^{1 to} R ⁶ are each independently an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group, and the structure thereof may include a hetero atom; g and j are each independently 1 And k is an integer of 0 or 1 and g + j + k is 5 or less; h is an integer of 1 or more, and l and m are each independently 0 or an integer of 1 or more; And h + 1 + m is 4 or less; i is an integer of 1 or more, n and o are each independently 0 or an integer of 1 or more, and i + n + o is 4 or less; p is 1. ]
A compound represented by der Ru laminate. Laminate according to claim 1 Symbol mounting protection rate of a phenolic hydroxyl group of the substrate in the component (A) is 5 to 50 mol%. The laminate according to claim 1 or 2, wherein the protective film has a thickness of 40 nm or less. A laminated body according to any one of claims 1 to 3 is formed on a substrate, the resist layer is selectively exposed with an electron beam or EUV through the protective film, and PEB (post-exposure heating). Then, the protective film is removed, and the resist layer is developed to form a resist pattern.