阅读说明：本技术 抗蚀剂组合物和抗蚀剂膜 (Resist composition and resist film ) 是由 星野学 于 2019-01-17 设计创作，主要内容包括：本发明提供一种抗蚀剂组合物和形成有良好图案的抗蚀剂膜,该抗蚀剂组合物能够提高旋转涂布时的对基材的涂覆性(涂膜性)和抗蚀剂膜的密合性,且能够形成良好的图案。该抗蚀剂组合物包含聚合物、溶剂和芳香族乙烯基单体,上述芳香族乙烯基单体相对于上述聚合物的含量为10质量ppm以上且30000质量ppm以下。(The invention provides a resist composition and a resist film with a good pattern, wherein the resist composition can improve coating property (film coating property) to a substrate and adhesion of the resist film during spin coating, and can form a good pattern. The resist composition contains a polymer, a solvent, and an aromatic vinyl monomer, and the content of the aromatic vinyl monomer relative to the polymer is 10 mass ppm or more and 30000 mass ppm or less.)

1. A resist composition comprising a polymer, a solvent and an aromatic vinyl monomer,

the content of the aromatic vinyl monomer relative to the polymer is more than 10 mass ppm and less than 30000 mass ppm.

2. The resist composition of claim 1, wherein the aromatic vinyl monomer is an α -methylstyrene derivative.

3. The resist composition of claim 1 or 2, further comprising an alpha-halo (meth) acrylate monomer,

the content of the alpha-halogenated (meth) acrylate monomer relative to the polymer is 5 mass ppm or more and 2000 mass ppm or less.

4. The resist composition according to any one of claims 1 to 3, wherein the polymer has an α -methylstyrene monomer unit and an α -methylmethacrylate monomer unit.

5. A resist film formed on a substrate using the resist composition according to any one of claims 1 to 4.

Technical Field

The invention relates to a resist composition and a resist film.

Background

Conventionally, in the field of semiconductor manufacturing and the like, a polymer, which has a main chain cut-off type and has increased solubility in a developer by cutting the main chain by irradiation with ionizing radiation such as electron beam or Extreme Ultraviolet (EUV) or short-wavelength light such as ultraviolet (hereinafter, the combination of ionizing radiation and short-wavelength light may be referred to as "ionizing radiation" or the like), has been used as a main chain cut-off type positive resist.

As a highly sensitive main chain cleavage type positive resist, for example, patent document 1 discloses a positive resist containing an α -methylstyrene/α -methyl chloroacrylate copolymer containing α -methylstyrene units and α -methyl chloroacrylate units.

Patent document 1 does not disclose a specific method for producing an α -methyl chloroacrylate α -methylstyrene copolymer. Conventionally, in a specific production process of such a copolymer, the following method has been employed: and a method in which, after the polymerization step, the copolymer separated from the reaction mixture is dissolved in an organic solvent, and the solution is dropped into a poor solvent to precipitate the copolymer, and the method is repeated, thereby recovering a purified copolymer. Such an electron beam resist composition containing an α -methyl chloroacrylate α -methylstyrene copolymer has a problem that impurities are generated in a dry etching process and defects are easily generated in a photomask.

Further, in patent document 1, a positive resist containing an α -methylstyrene α -methyl chloroacrylate copolymer has a problem that excessive film reduction occurs in a state where the irradiation amount of ionizing radiation or the like is small. Therefore, there is still room for improvement in the positive resist containing an α -methylstyrene α -methyl chloroacrylate copolymer described in patent document 1, in order to further reduce the film reduction rate in a state where the exposure dose of ionizing radiation or the like is low.

In order to solve such a problem, an electron beam resist composition in which an α -methylmethacrylate- α -methylstyrene copolymer is used as a resin component and which does not generate impurities in a dry etching process has been studied (for example, see patent document 2), and a positive resist having a low film reduction rate in a state in which an irradiation amount of ionizing radiation or the like is small has also been studied (for example, see patent document 3).

Disclosure of Invention

Problems to be solved by the invention

However, the resist compositions described in patent documents 2 and 3 have room for improvement in terms of improving coatability (coatability) to a substrate and adhesion of a resist film at the time of spin coating and forming a good pattern.

Accordingly, an object of the present invention is to provide a resist composition which can improve coatability (coatability) to a substrate and adhesion of a resist film at the time of spin coating and can form a good pattern.

Further, the present invention aims to provide a resist film having a good pattern formed thereon.

Means for solving the problems

The present inventors have conducted intensive studies in order to achieve the above object. Then, the present inventors have found that if a resist composition contains a polymer, a solvent, and an aromatic vinyl monomer, and the content of the aromatic vinyl monomer with respect to the polymer is 10 mass ppm or more and 30000 mass ppm or less, the coating property (film coating property) to a substrate and the adhesion of a resist film at the time of spin coating can be improved, and a good pattern can be formed, and have completed the present invention.

That is, the present invention has an object to advantageously solve the above problems, and the resist composition of the present invention is characterized by comprising a polymer, a solvent, and an aromatic vinyl monomer, wherein the content of the aromatic vinyl monomer with respect to the polymer is 10 mass ppm or more and less than 30000 mass ppm. The resist composition containing a polymer, a solvent and an aromatic vinyl monomer, wherein the content of the aromatic vinyl monomer relative to the polymer is 10 mass ppm or more and less than 30000 mass ppm can improve the coating property (film coating property) to a substrate and the adhesion of a resist film during spin coating, and can form a good pattern.

In the present invention, the "content of the aromatic vinyl monomer relative to the polymer" can be determined by calculation using a chromatogram obtained by gas chromatography.

Here, the resist composition of the present invention preferably has the aromatic vinyl monomer as an α -methylstyrene derivative. This is because, if the aromatic vinyl monomer is an α -methylstyrene derivative, the coating property (coatability) to a substrate and the adhesion of a resist film at the time of spin coating can be reliably improved, and a good pattern can be reliably formed.

Further, the resist composition of the present invention preferably: further comprises an alpha-halogenated (meth) acrylate monomer, and the content of the alpha-halogenated (meth) acrylate monomer relative to the polymer is 5 mass ppm or more and 2000 mass ppm or less. This is because, if an α -halo (meth) acrylate monomer is further contained and the content of the α -halo (meth) acrylate monomer with respect to the polymer is 5 ppm by mass or more and 2000 ppm by mass or less, the coating property (coatability) to a substrate and the adhesion of a resist film at the time of spin coating can be further improved, and a good pattern can be further formed.

In the present invention, the "content of the α -halo (meth) acrylate monomer with respect to the polymer" can be determined by calculation using a chromatogram obtained by gas chromatography.

Further, the resist composition of the present invention is preferably such that the above polymer has an α -methylstyrene monomer unit and an α -methylmethacrylate monomer unit. This is because, if the polymer has an α -methylstyrene monomer unit and an α -chloromethyl methacrylate monomer unit, the coating property (coatability) to a substrate and the adhesion of a resist film at the time of spin coating can be reliably improved, and a good pattern can be reliably formed.

The present invention is also directed to advantageously solve the above problems, and a resist film of the present invention is formed on a substrate using any one of the above resist compositions. When a resist film is formed on a substrate using any of the above-described resist compositions, a resist film having a good pattern formed thereon can be obtained.

Effects of the invention

According to the resist composition of the present invention, the coating property (coatability) to a substrate and the adhesion of a resist film at the time of spin coating can be improved, and a good pattern can be formed.

Further, according to the resist film of the present invention, a good pattern can be formed.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

Here, the resist composition of the present invention can be preferably used as a positive resist.

(resist composition)

The resist composition of the present invention comprises a polymer, a solvent and an aromatic vinyl monomer, and optionally further comprises an α -halo (meth) acrylate monomer, and known additives which can be compounded in the resist composition. Further, since the resist composition of the present invention contains a polymer as a resist, if a resist film obtained by coating and drying the resist composition of the present invention is used, a pattern with high resolution can be formed well.

< polymers >

The polymer is not particularly limited, and examples thereof include a copolymer having an aromatic vinyl monomer unit and an α -halogenated (meth) acrylate monomer unit, a copolymer having an aromatic vinyl monomer unit and a (meth) acrylate monomer unit, a homopolymer formed from an aromatic vinyl monomer unit, and a homopolymer formed from an α -halogenated (meth) acrylate monomer unit. These may be used alone in 1 kind, or 2 or more kinds may be used in combination at an arbitrary ratio.

Among these, a copolymer having an aromatic vinyl monomer unit and an α -halogenated (meth) acrylate monomer unit, a homopolymer formed of a (meth) acrylate monomer unit, and more preferably a copolymer having an aromatic vinyl monomer unit and an α -halogenated (meth) acrylate monomer unit are preferable.

< aromatic vinyl monomer Unit >

The aromatic vinyl monomer unit is a structural unit derived from an aromatic vinyl group. Further, if the polymer has an aromatic vinyl monomer unit, when used as a resist, the polymer exhibits excellent dry etching resistance due to the protective stability of the aromatic compound.

The polymer preferably contains an aromatic vinyl monomer unit in a proportion of 30 mol% or more and 70 mol% or less.

The aromatic vinyl monomer unit is not particularly limited, and examples thereof include an α -methylstyrene monomer unit, an α -methylnaphthalene monomer unit, a benzyl methacrylate monomer unit, and a styrene monomer unit. These can be used alone in 1 kind, also can be more than 2 kinds in any ratio combination use.

Among these, α -methylstyrene monomer units are preferred.

-alpha-methylstyrene monomer units

Here, the α -methylstyrene monomer unit is a structural unit derived from α -methylstyrene. Further, if the polymer has an α -methylstyrene monomer unit, excellent dry etching resistance is exhibited based on the protection stability of the benzene ring when used as a resist.

The polymer preferably contains an α -methylstyrene monomer unit in a proportion of 30 to 70 mol%.

< alpha-halogenated (meth) acrylate monomer Unit >)

The α -halo (meth) acrylate monomer unit is a structural unit derived from an α -halo (meth) acrylate. Further, if the polymer has an α -halo (meth) acrylate monomer unit, a halogen atom is detached upon irradiation with ionizing radiation or the like, and the main chain is easily cleaved by a β cleavage reaction. Therefore, a resist comprising the above polymer may exhibit high sensitivity.

The polymer preferably contains an α -halogenated (meth) acrylate monomer unit in a proportion of 30 mol% or more and 70 mol% or less.

The α -halogenated (meth) acrylate monomer unit is not particularly limited, and examples thereof include α -chloroacrylate monomers such as α -methyl chloroacrylate monomer unit, α -ethyl chloroacrylate monomer unit, α -benzyl chloroacrylate monomer unit, α -1-adamantyl chloroacrylate monomer unit, α -2,2,3,3, 3-pentafluoropropyl chloroacrylate monomer unit, and α -2,2,3,3,4,4, 4-heptafluorobutyl chloroacrylate monomer unit. These can be used alone in 1 kind, also can be more than 2 kinds in any ratio combination use.

Among these, a-methyl chloroacrylate monomer units are preferred.

-methyl alpha-chloroacrylate monomer units

Here, the monomer unit of α -methyl chloroacrylate is a structural unit derived from α -methyl chloroacrylate. Further, if the polymer has a methyl α -chloroacrylate monomer unit, a chlorine atom is removed when ionizing radiation or the like is irradiated, and the main chain can be easily cleaved by a β cleavage reaction. Therefore, a resist comprising the above polymer may exhibit high sensitivity.

The polymer preferably contains an α -methyl chloroacrylate monomer unit in a proportion of 30 to 70 mol%.

Here, if the polymer contains a structural unit (α -methyl chloroacrylate unit) from α -methyl chloroacrylate having a chloro group (-Cl) at the α -position, the main chain can be easily cut to be low molecular weight upon irradiation with ionizing radiation or the like (e.g., electron beam, KrF laser, ArF laser, EUV laser, etc.).

< (meth) acrylate monomer units >)

The (meth) acrylate monomer unit is a structural unit derived from a (meth) acrylate, and in the present specification, the (meth) acrylate monomer unit does not include the above-mentioned "methyl α -chloroacrylate monomer unit". Further, if the polymer has a (meth) acrylate monomer unit, a high molecular weight product can be easily obtained.

The (meth) acrylate monomer unit is not particularly limited, and examples thereof include a Methyl Methacrylate (MMA) monomer unit, an ethyl methacrylate monomer unit, and a benzyl methacrylate monomer unit. These can be used alone in 1 kind, also can be more than 2 kinds in any ratio combination use.

Of these, Methyl Methacrylate (MMA) monomer units are preferred.

Methyl Methacrylate (MMA) monomer units

Here, the Methyl Methacrylate (MMA) monomer unit is a structural unit derived from Methyl Methacrylate (MMA). Further, if the polymer has a Methyl Methacrylate (MMA) monomer unit, a high molecular weight product can be easily obtained and dissolved in a solvent.

< weight average molecular weight > <

The weight average molecular weight (Mw) of the polymer is preferably 50000 or more, more preferably 55000 or more, particularly preferably 60000 or more, preferably 500000 or less, more preferably 350000 or less, still more preferably 100000 or less, particularly preferably 85000 or less, and most preferably 73000 or less. When the weight average molecular weight (Mw) of the polymer is 50000 or more, the film reduction rate at low irradiation can be further reduced, and when it is 500000 or less, it can be favorably used as a resist having excellent characteristics such as sensitivity.

In the present specification, "weight average molecular weight (Mw)" can be measured by gel permeation chromatography.

< number average molecular weight > <

The number average molecular weight (Mn) of the polymer is preferably 25000 or more, more preferably 30000 or more, further preferably 42000 or more, preferably 100000 or less, more preferably 76000 or less, and particularly preferably 51000 or less. When the number average molecular weight (Mn) of the polymer is 25000 or more, the film reduction rate at a low irradiation dose can be further reduced, and when it is 100000 or less, the polymer can be favorably used as a resist having excellent characteristics such as sensitivity.

In the present specification, "number average molecular weight (Mn)" can be measured by gel permeation chromatography.

< molecular weight distribution >)

The molecular weight distribution (Mw/Mn) of the polymer is preferably less than 1.48, more preferably 1.47 or less, particularly preferably 1.43 or less, and further preferably 1.20 or more. If the molecular weight distribution (Mw/Mn) of the polymer is less than 1.48, the polymer can be suitably used as a resist having excellent characteristics such as a gamma value, and if it is 1.20 or more, the polymer can be easily produced.

In the present specification, the term "molecular weight distribution (Mw/Mn)" refers to the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn).

< preparation method of Polymer >)

The polymer having the above properties can be produced, for example, by the following method: the polymer obtained is purified after polymerizing a monomer composition containing an aromatic vinyl monomer such as α -methylstyrene and an α -halogenated (meth) acrylate monomer such as α -methyl chloroacrylate.

The composition, molecular weight distribution, weight average molecular weight, number average molecular weight of the polymer, and the ratio of each molecular weight component in the polymer can be adjusted by changing the polymerization conditions and purification conditions. Specifically, for example: if the polymerization temperature is increased, the weight average molecular weight and the number average molecular weight can be reduced. Further, if the polymerization time is shortened, the weight average molecular weight and the number average molecular weight can be reduced.

Polymerization of the monomer composition

Here, as the monomer composition for the preparation of the polymer, a mixture of: which comprises monomers, solvent, polymerization initiator and optionally additives. Further, the polymerization of the monomer composition can be carried out using a known method. In particular, as the monomer, an aromatic vinyl monomer such as α -methylstyrene, an α -halogenated (meth) acrylate monomer such as α -methyl chloroacrylate, a (meth) acrylate monomer such as Methyl Methacrylate (MMA), or the like is preferably used, as the solvent, Cyclopentanone (CPN) or the like is preferably used, and as the polymerization initiator, a radical polymerization initiator such as azobisisobutyronitrile or the like is preferably used.

The composition of the polymer can be adjusted by changing the content ratio of each monomer in the monomer composition used for polymerization. The ratio of the high-molecular-weight component contained in the polymer can be adjusted by changing the amount of the polymerization initiator, and for example, if the amount of the polymerization initiator is decreased, the ratio of the high-molecular-weight component can be increased.

The polymerization product obtained by polymerizing the monomer composition is not particularly limited, and can be recovered by adding a good solvent such as tetrahydrofuran to a solution containing the polymerization product, then dropwise adding the solution to which the good solvent is added to a poor solvent such as methanol or a mixed solvent of tetrahydrofuran and methanol, and solidifying the polymerization product, and then purified in the following manner.

< purification of polymerization product >)

The purification method used for purifying the obtained polymerization product to obtain a polymer having the above properties is not particularly limited, and known purification methods such as reprecipitation and column chromatography can be used. As the purification method, a reprecipitation method is particularly preferably used.

Further, the purification of the polymerization product may be repeated several times.

Moreover, the purification of the polymerization product based on the reprecipitation method can be performed by, for example: the obtained polymerization product is dissolved in a good solvent such as tetrahydrofuran, and the obtained solution is added dropwise to (i) a poor solvent such as methanol or (ii) a mixed solvent of a good solvent such as tetrahydrofuran and a poor solvent such as methanol to precipitate a part of the polymerization product. In this way, if the purification of the polymerization product is performed by dropping a solution of the polymerization product into a mixed solvent of a good solvent and a poor solvent, the content of the monomer (residual monomer) remaining in the obtained polymerization product, the molecular weight distribution, the weight average molecular weight, the number average molecular weight, and the ratio of components having low molecular weights in the obtained polymerization product can be easily adjusted by changing (i) the number of purifications by the reprecipitation method, (ii) the types of the good solvent and the poor solvent, (iii) the mixing ratio of the good solvent and the poor solvent, and the like. Specifically, for example, the larger the number of purifications by the reprecipitation method, the smaller the content of the residual monomer can be made, and the higher the proportion of the good solvent in the mixed solvent, the higher the molecular weight of the polymer precipitated in the mixed solvent can be.

In the case of purifying the polymerization product by the reprecipitation method, as the polymer contained in the resist composition of the present invention, a polymer precipitated in a mixed solvent of a good solvent and a poor solvent may be used, or a polymer not precipitated from a mixed solvent (that is, a polymer dissolved in a mixed solvent) may be used. Here, the polymer that has not precipitated from the mixed solvent can be recovered from the mixed solvent by a known method such as concentration and drying.

< solvent >

As the solvent in the resist composition of the present invention, if the polymer is soluble, a known solvent can be used, and THF, anisole, cyclopentanone, methyl 3-methoxypropionate, or the like can be used, for example. These can be used alone in 1 kind, also can be more than 2 kinds in any ratio combination use.

Among these, methyl 3-methoxypropionate is preferably used as the solvent from the viewpoint of obtaining a resist composition having an appropriate viscosity to improve the coatability of the resist composition.

< aromatic vinyl monomer >

The aromatic vinyl monomer in the resist composition of the present invention is not particularly limited, and examples thereof include α -methylstyrene derivatives such as α -methylstyrene monomer and 4-fluoro- α -methylstyrene; methacrylate derivatives such as benzyl methacrylate and adamantyl methacrylate; styrene derivatives such as styrene and 4-fluorostyrene; alpha-methylnaphthalene monomers, and the like. These may be used alone in 1 kind, or 2 or more kinds may be used in combination at an arbitrary ratio.

Among these, α -methylstyrene derivatives are preferable, and α -methylstyrene monomers are more preferable, because the content of the polymer during polymerization can be easily adjusted.

The content of the aromatic vinyl monomer to the polymer is not particularly limited as long as it is 10 mass ppm or more and 30000 mass ppm or less, but is preferably 600 mass ppm or more, more preferably 1000 mass ppm or more from the viewpoint of coatability (coatability) of the resist composition, and is preferably 30000 mass ppm or less, more preferably 10000 mass ppm or less, further preferably 3700 mass ppm or less, particularly preferably 2000 mass ppm or less from the viewpoint of bridge defect resistance (bridge defect resistance), pattern collapse resistance, and γ value (pattern clearness) of the formed resist pattern.

< alpha-halogenated (meth) acrylate monomer >

The α -halogenated (meth) acrylate monomer in the resist composition of the present invention is not particularly limited, and examples thereof include α -chloroacrylate monomers such as α -methylacrylate monomer, α -ethylacrylate, α -benzylchloroacrylate, α -1-adamantyl chloroacrylate, α -2,2,3,3, 3-pentafluoropropylchloroacrylate, and α -2,2,3,3,4,4, 4-heptafluorobutyl chloroacrylate; α -fluoroacrylate monomers such as α -fluoroacrylate monomer, α -fluoroacrylate benzyl ester, α -fluoroacrylate 1-adamantyl ester, α -fluoroacrylate 2,2,3,3, 3-pentafluoropropyl ester, and α -chloroacrylate 2,2,3,3,4,4, 4-heptafluorobutyl ester. These may be used alone in 1 kind, or 2 or more kinds may be used in combination at an arbitrary ratio.

Among these, α -chloroacrylate monomers are preferable, and α -methylacrylate monomers are more preferable, from the viewpoint of the main chain cleavage efficiency and the ease of polymerization.

The content of the α -halo (meth) acrylate monomer relative to the polymer is not particularly limited, but is preferably 5 mass ppm or more, more preferably 200 mass ppm or more, and particularly preferably 300 mass ppm or more from the viewpoint of the adhesion of the resist composition, and is preferably 2000 mass ppm or less, particularly preferably 1000 mass ppm or less, and most preferably 600 mass ppm or less from the viewpoint of the pattern collapse resistance and γ value (pattern clearness) of the formed resist pattern.

(resist film)

The resist film of the present invention is formed on a substrate by using the resist composition of the present invention.

The thickness of the resist film of the present invention is not particularly limited, but is preferably 20nm or more, more preferably 30nm or more from the viewpoint of etching resistance, and is preferably 200nm or less, more preferably 100nm or less from the viewpoint of formation of micro wiring.

< substrate >

The material of the substrate is not particularly limited, and examples thereof include silicon, quartz, chromium, and molybdenum. These may be used alone in 1 kind, or 2 or more kinds may be used in combination at an arbitrary ratio.

< method for Forming resist film >

The method for forming the resist film is not particularly limited, and a resist film can be formed on a substrate by applying a resist composition on a substrate using, for example, a spin coater, and heating the applied resist composition for a predetermined time to a predetermined temperature.