JP7341932B2 - Composition for forming lower layer film, method for forming pattern, method for producing copolymer and composition for forming lower layer film - Google Patents

Description

The present invention relates to a composition for forming an underlayer film, a method for forming a pattern, a copolymer, and a method for producing the composition for forming an underlayer film.

Electronic devices such as semiconductors are required to be highly integrated through miniaturization, and miniaturization and diversification of shapes of semiconductor device patterns are being considered. As a method for forming such a pattern, a lithography method using a photoresist and a pattern forming method by self-assembly using a directed self-assembly material are known. For example, in the lithography method using photoresist, a thin film of photoresist is formed on a semiconductor substrate such as a silicon wafer, and active light such as ultraviolet rays is irradiated through a mask pattern on which a semiconductor device pattern is drawn, and then developed. This is a processing method in which fine irregularities corresponding to the pattern are formed on the substrate by etching the substrate using the resulting photoresist pattern as a protective film.

In order to form a fine pattern, a method of forming a pattern after forming a lower layer film on a substrate such as a silicon wafer is also being considered. For example, Patent Document 1 discloses a composition for forming a resist underlayer film, which contains [A] polysiloxane and [B] a solvent, and the [B] solvent contains (B1) a tertiary alcohol. things are listed. Patent Document 2 describes a coating process of applying a composition for forming a resist underlayer film containing a compound having an aromatic ring onto a substrate, and a coating process in which the resulting coating film is heated at a temperature exceeding 450°C in an atmosphere with an oxygen concentration of less than 1% by volume. A method for forming a resist underlayer film is described, which includes a heating step of heating at a temperature of 800° C. or lower.

Further, Patent Document 3 describes a composition for forming a lower layer film containing a dextrin ester compound in which 50% or more of dextrin is esterified, a crosslinkable compound, and an organic solvent. Patent Document 4 describes a composition for forming an underlayer film for lithography that includes a cyclodextrin containing an clathrate molecule.

Under such circumstances, the present inventors have developed a composition for forming an underlayer film, which contains a copolymer and an organic solvent to increase the residual rate of the underlayer film and is used for pattern formation.
The copolymer is
(a) a unit derived from a sugar derivative;
(b) a unit derived from a compound having an antireflection function;
(c) a unit derived from a compound capable of cross-coupling the copolymer;
The unit derived from the sugar derivative (a) is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative,
The composition for forming a lower layer film is for introducing a metal, and a composition for forming a lower layer film is being developed (Patent Document 5)

JP 2016-170338 Publication Japanese Patent Application Publication No. 2016-206676 International Publication No. 2005/043248 Japanese Patent Application Publication No. 2007-256773 International Publication No. 2019/163975

After the coating film formed from the composition for forming an underlayer film is heat-treated to become the underlayer film, it becomes difficult to dissolve in the organic solvent contained in the resist forming composition etc. (i.e., the composition used in the composition for forming the underlayer film The lower layer film survival rate of the material is high). However, the underlayer film survival rate (solvent resistance) of the underlayer film formed using the conventional underlayer film forming composition could not be said to be sufficiently high.

After forming a pattern on the lower layer film, an etching process is sometimes performed to use the pattern as a protective film and further process the pattern shape on the silicon wafer substrate. The protective film did not have sufficient etching resistance, and problems remained in pattern processability on the substrate.

Therefore, an object of the present invention is to provide a composition for forming an underlayer film that can form an underlayer film that has a high residual rate in organic solvents and has excellent etching resistance.

As a result of intensive studies to solve the above problems, the present inventors discovered that (a) a unit derived from a sugar derivative, (b) a unit derived from a compound having an antireflection function, and (c) a unit derived from a sugar derivative; ) By using a copolymer containing a unit derived from a compound capable of cross-coupling the copolymer and (d) a unit having a functional group that promotes gas permeation to the underlayer film as a material for the composition for forming the underlayer film, The present inventors have discovered that a lower layer film with a high residual rate against organic solvents can be obtained, and that excellent etching resistance can be imparted to the lower layer film by increasing the amount of metal introduced, and the present invention has been completed.
Therefore, the present invention provides the following items.

[2] An underlayer film forming composition used for pattern formation, containing a copolymer and an organic solvent,
The copolymer is
(a) a unit derived from a sugar derivative;
(b) a unit derived from a compound having an antireflection function;
(c) a unit derived from a compound capable of cross-coupling the copolymer;
(d) a unit having a functional group that promotes gas permeation to the underlying film;
The unit derived from the sugar derivative (a) is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative,
The composition for forming a lower layer film is for introducing a metal.
[2] (d) The unit having a functional group that promotes gas permeation to the lower layer membrane is a unit derived from an ester of a C10 or higher aliphatic alcohol or a C10 or higher alkoxy polyalkylene glycol and (meth)acrylic acid. The composition for forming a lower layer film according to [1].
[3] The unit derived from the compound having an antireflection function (b) is at least one type selected from the group consisting of a unit derived from a benzene ring-containing compound and a unit derived from a naphthalene ring-containing compound, [ 1] or the composition for forming a lower layer film according to [2].
[4] The unit derived from the sugar derivative (a) is at least one type selected from the group consisting of a unit derived from a cellulose derivative, a unit derived from a hemicellulose derivative, and a unit derived from a xylooligosaccharide derivative, [1 ] to [3]. The composition for forming a lower layer film according to any one of [3].
[5] A pattern forming method comprising the step of forming a lower layer film using the composition for forming a lower layer film according to any one of [1] to [4].
[6] The pattern forming method according to [5], including the step of introducing metal into the lower layer film.
[7] (a) A unit derived from a sugar derivative,
(b) a unit derived from a compound having an antireflection function;
(c) a unit derived from a compound capable of cross-coupling the copolymer;
(d) a unit having a functional group that promotes gas permeation to the underlying film;
(a) A copolymer in which the sugar derivative-derived unit is at least one type selected from pentose derivative-derived units and hexose derivative-derived units.
[8] (d) The unit having a functional group that promotes gas permeation to the lower layer membrane is a unit derived from an ester of a C10 or higher aliphatic alcohol or a C10 or higher alkoxy polyalkylene glycol and (meth)acrylic acid. The copolymer according to [7], which is
[9] The unit according to [7] or [8], wherein the unit derived from the compound having an antireflection function (b) is at least one type selected from the group consisting of units derived from benzene ring-containing compounds. copolymer.
[10] The unit derived from the sugar derivative (a) is at least one type selected from the group consisting of a unit derived from a cellulose derivative, a unit derived from a hemicellulose derivative, and a unit derived from a xylooligosaccharide derivative, [7 ] to [9]. The copolymer according to any one of [9].
[11] (a) A sugar derivative having a polymerizable unsaturated saturated group, (b) a polymerizable monomer having an antireflection function, (c) a polymerizable monomer having a cross-coupling group, and (d) A method for producing a copolymer, the method comprising the step of polymerizing a polymerizable monomer having a functional group that promotes gas permeation to an underlying membrane,
The method, wherein the sugar derivative (a) having a polymerizable unsaturated group is at least one selected from a pentose derivative having a polymerizable unsaturated group and a hexose derivative having a polymerizable unsaturated group.

According to the present invention, it is possible to form a lower layer film that has a high survival rate with respect to organic solvents and has excellent etching resistance.

FIG. 1 is a cross-sectional view showing an example of the structure of a substrate and a lower layer film.

In the following, the present invention will be explained in detail. Although the constituent elements described below may be explained based on typical embodiments and specific examples, the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after the "~" as lower and upper limits.

Note that in this specification, substituents that are not specified as substituted or unsubstituted are meant to have the meaning that they may have any substituent. Moreover, in this specification, "(meth)acrylate" means acrylate or methacrylate.

(Composition for forming lower layer film)
In one embodiment, the present invention relates to a composition for forming an underlayer film that includes a copolymer and an organic solvent and is used for pattern formation. The copolymer contains (a) units derived from a sugar derivative, (b) units derived from a compound having an antireflection function, (c) units derived from a compound capable of cross-coupling the copolymer, and (d) and a unit having a functional group that promotes gas permeation to the underlying film. (a) The unit derived from a sugar derivative is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative, and the composition for forming a lower layer film provides a metal introduction unit.

The composition for forming a lower layer film of the present invention can form a lower layer film that has a high residual rate in organic solvents and has excellent etching resistance. Since the lower layer film formed from the lower layer film forming composition of the present invention has excellent etching resistance, it can improve the etching processability of substrates and the like. Furthermore, since the copolymer contained in the composition for forming the underlayer film of the present invention contains the plurality of structural units described above, it has high solubility in organic solvents, but after curing to form the underlayer film, Another feature is that it remains undissolved in the organic solvent contained in the resist forming composition.

Since the units derived from the sugar derivatives of the copolymer (hereinafter also referred to as units (a)) contain many crosslinking reaction moieties, crosslinking tends to be easily promoted by heating (regardless of whether or not a crosslinking agent is added). . Therefore, the residual rate of the lower layer film after the coating film is heated to become the lower layer film can be increased. That is, after forming the lower layer film by heat-treating the coating film formed from the composition for forming the lower layer film, the solubility of the copolymer in the organic solvent can be lowered. Furthermore, by having the unit (a) in the copolymer, etching processability can be improved.

The residual rate of the lower layer film is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. Here, the residual rate of the lower layer film is measured before and after applying a 50:50 (mass ratio) mixture of propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether, which are solvents used in photoresist, to the lower layer film (before and after cleaning). ) is the value calculated from the thickness of the lower layer film using the following formula:
Lower layer film survival rate (%) = Lower layer film thickness after cleaning (μm) / Lower layer film thickness before cleaning (μm) x 100

Etching processability can be evaluated by the following method. First, a composition for forming a lower layer film is applied to a silicon substrate to form a lower layer film, and then the lower layer film is formed into a line-and-space pattern shape, and the silicon substrate is etched. Thereafter, the pattern-formed surface of the silicon substrate is observed with a scanning electron microscope to confirm the etching processability. If the pattern shape of the silicon substrate is in a state where there is no line collapse in one field of view of a scanning electron microscope, it can be determined that the etching processability is good.

Further, in the composition for forming a lower layer film of the present invention, since the copolymer has the unit (a), a large amount of metal can be introduced into the lower layer film. Therefore, it can be said that the composition for forming a lower layer film of the present invention is a material for introducing metal. The copolymer contained in the composition for forming a lower layer film can react (bond) with a metal to form a lower layer film containing a metal. Such a lower layer film is harder than a lower layer film containing no metal, and thus can exhibit excellent etching processability. Here, the copolymer contained in the composition for forming the lower layer film is preferably one that reacts (bonds) with the metal at multiple sites in one molecule of the copolymer, and the more sites that react (bond) with the metal, the more likely the metal will be introduced. rate becomes higher. In the present invention, the metal introduction rate is increased by reacting (bonding) the oxygen atoms and metal atoms contained in the copolymer, and such a high metal introduction rate is due to the copolymer having the unit (a). achieved. Note that the bond between the oxygen atom and metal atom contained in the copolymer is not particularly limited, but, for example, it is preferable that the oxygen atom and metal atom contained in the copolymer form a coordinate bond or an ionic bond.

The metal introduction rate in the lower layer film is preferably at least 5 at% (atomic percent), more preferably at least 8 at%, even more preferably at least 10 at%, even more preferably at least 15 at%. . The metal introduction rate can be calculated, for example, by the following method. First, a lower layer film formed from a composition for forming a lower layer film is placed in an ALD (atomic layer deposition apparatus), into which Al(CH ₃ ) ₃ gas is introduced at 95° C., and then water vapor is introduced therein. By repeating this operation three times, Al is introduced into the lower layer film. EDX analysis (energy dispersive X-ray analysis) was performed on the lower layer film after Al introduction using an electron microscope JSM7800F (manufactured by JEOL Ltd.) to calculate the ratio of Al components (Al content), which was calculated as the metal introduction rate. shall be.

The unit derived from a compound having an antireflection function of the copolymer (hereinafter also referred to as unit (b)) has the property of absorbing light. For the anti-reflection function of unit (b), a coating film with a thickness of 0.1 μm is formed from a coating solution consisting of the monomer of unit (b) and a solvent, and the coating film is exposed to ultraviolet light (for example, ultraviolet light with a wavelength of 193 nm). When the reflectance is 30% or less, it can be evaluated that the unit (b) has a light reflection prevention function. Note that the reflectance of the coating film can be evaluated by measuring with a spectrophotometer. As the spectrophotometer, for example, V770EX manufactured by JASCO Corporation can be used, and it is preferable to perform the measurement with an integrating sphere installed in the spectrophotometer. In addition, when a coating film cannot be formed from the monomer of unit (b), a coating film may be formed from a coating liquid containing a polymer composed of unit (b).

By having the unit (b) in the copolymer, the lower layer film formed from the composition for forming a lower layer film can exhibit an antireflection function. Therefore, when forming a resist film on the lower layer film and exposing it to form a pattern, the pattern shape can be formed with high accuracy. The light reflection prevention function of the lower layer film can be evaluated by irradiating the lower layer film with ultraviolet rays (for example, ultraviolet rays with a wavelength of 193 nm) and measuring the reflectance with a spectrophotometer. As the spectrophotometer, for example, V770EX manufactured by JASCO Corporation can be used, and it is preferable to perform the measurement with an integrating sphere installed in the spectrophotometer. The ultraviolet reflectance (light reflectance) of the lower layer film is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less.

Furthermore, since the copolymer has a unit derived from a compound capable of cross-coupling the copolymer (hereinafter also referred to as unit (c)), the cross-coupling reaction of the copolymer can be promoted. Cross-coupling refers to the bonding of copolymers in the composition for forming a lower layer film by heating or photoreaction, or the bonding of functional groups within the copolymers. This makes it possible to increase the residual ratio of the lower layer film to organic solvents, and further improve etching processability. Furthermore, since the copolymer has the unit (c), it is possible to form a lower layer film that is resistant to cracking by heat treatment in the atmosphere at a relatively low temperature. For example, even if the lower layer film is placed under severe conditions such as high temperature conditions, the occurrence of cracks is suppressed.

The presence or absence of the unit (c) in the copolymer can be determined by detecting the change in the peak of the functional group before and after curing the composition for forming the lower layer film using FT-IR. For example, if the compound capable of cross-coupling the copolymer is glycidyl methacrylate, the copolymer will be cross-coupled by curing the composition for forming the underlayer film, the peak around 916 cm ^-1 will disappear, and the peak around 1106 cm ^-1 will disappear. A peak derived from an ether group and a peak derived from a hydroxyl group near 3160 to 3600 cm ^-1 are detected. This makes it possible to evaluate that cross-coupling of the copolymer has occurred. Specifically, for example, using the unchanged peak height of a methyl group as a reference functional group, the cross-coupling reaction rate is calculated from the ratio of the peak height that disappears due to cross-coupling, and the cross-coupling reaction rate is 95. %, it can be determined that cross-coupling of the copolymer has occurred, that is, the copolymer contains units (c):
Cross-coupling reaction rate (%) = (peak height of functional group derived from cross-coupling group after curing/peak height of reference functional group) / (peak height of functional group derived from cross-coupling group before curing) / peak height of reference functional group) x 100

The lower layer film formed from the lower layer film forming composition of the present invention is, for example, a film (protective film) provided on a substrate such as a silicon wafer in order to form a pattern on the substrate. The lower layer film may be a film provided in direct contact with the substrate, or may be a film laminated on the substrate via another layer. The lower layer film is processed into a pattern shape desired to be formed on the substrate, and the portion left as the pattern shape becomes a protective film in a subsequent etching process. After the pattern is formed on the substrate, the lower layer film (protective film) is generally removed from the substrate. In this way, the lower layer film is used in the process of forming a pattern on the substrate.

The lower layer film formed from the composition for forming a lower layer film of the present invention exhibits excellent etching resistance when processing a pattern shape on a substrate, and the etching resistance of such a lower layer film is expressed by, for example, the following formula: It can be evaluated by the etching selectivity calculated by:
Etching selectivity = maximum depth of etched part of substrate / (average thickness of lower layer film before etching process - average thickness of lower layer film after etching process)
The depth of the etched portion of the substrate and the thickness of the underlying film before and after the etching process can be measured, for example, by observing a cross section of the substrate with a scanning electron microscope (SEM). The depth of the etched portion of the substrate is the maximum depth of the portion etched by the etching process, and the thickness of the lower layer film before and after the etching process is the maximum thickness of the remaining portion of the lower layer film. The etching selectivity calculated as described above is preferably larger than 1.5, more preferably 2 or more, even more preferably 3 or more, and even more preferably 4 or more. Note that the upper limit value of the etching selectivity is not particularly limited, but may be set to 200, for example.

Further, the composition for forming a lower layer film of the present invention may be used as a forming material for a photomask for forming a pattern. A photomask is formed by forming a predetermined pattern on a photomask substrate and performing steps such as etching and resist peeling.

<Copolymer>
The composition for forming a lower layer film of the present invention contains a copolymer. The copolymer includes units (a), units (b), units (c) and units (d). Here, the unit (a) is a unit derived from a sugar derivative, the unit (b) is a unit derived from a compound having an antireflection function, and the unit (c) is a unit derived from a compound capable of cross-coupling the copolymer. The unit (d) is a unit having a functional group that promotes gas permeation to the underlying film. Here, the unit (a) is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative. In one embodiment, the invention also provides a copolymer comprising units (a), units (b), units (c) and units (d).

The copolymer is preferably a random copolymer from the viewpoint of promoting crosslinking and increasing strength. Note that the copolymer may have a structure in which part of it is a random copolymer and part of it is a block copolymer.

The content of the copolymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, based on the total mass of the composition for forming the lower layer film. Further, the content of the copolymer is preferably 90% by mass or less, more preferably 80% by mass or less, and preferably 70% by mass or less with respect to the total mass of the composition for forming the underlayer film. More preferred.

Note that the copolymer is preferably made of an organic material. This is preferable from the viewpoint of better adhesion with organic resist materials, etc., compared to the case where an organic-inorganic hybrid material such as polysiloxane is included.

(Unit (a))
The unit (a) is a unit derived from a sugar derivative, and the unit derived from the sugar derivative is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative. In this way, by introducing a unit derived from a sugar derivative with many oxygen atoms as the unit (a) of the copolymer, a structure is created that facilitates coordination with metals, and a copolymer, A metal can be introduced into either the composition for forming a lower layer film or the lower layer film formed from the composition for forming a lower layer film, and as a result, etching processability can be improved. The underlying film into which metal is introduced in this way can serve as a higher performance mask within the lithography process.

The sugar derivative may be a sugar derivative derived from a monosaccharide, or may have a structure in which a plurality of sugar derivatives derived from a monosaccharide are bonded. When the copolymer is a block copolymer, the polymerization part a consisting of the unit (a) has a structure in which a plurality of sugar derivatives derived from monosaccharides are bonded.

The unit derived from a sugar derivative is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative.
The pentose derivative is not particularly limited as long as it has a structure derived from a pentose of a known monosaccharide or polysaccharide in which the hydroxyl group of the pentose is modified with at least a substituent. The pentose derivative is preferably at least one selected from hemicellulose derivatives, xylose derivatives, and xylooligosaccharide derivatives.

The hexose derivative is not particularly limited as long as it has a structure derived from a hexose in which the hydroxyl group of the hexose of a known monosaccharide or polysaccharide is modified with at least a substituent. The hexose derivative is preferably at least one selected from glucose derivatives and cellulose derivatives, and more preferably cellulose derivatives.
Among these, the unit derived from a sugar derivative (unit (a)) is preferably at least one selected from a unit derived from a cellulose derivative, a unit derived from a hemicellulose derivative, and a unit derived from a xylooligosaccharide derivative. Among these, it is more preferable that the polymer contains a unit derived from a xylose derivative or a xylooligosaccharide derivative, since the polymer has excellent solubility in a solvent. Note that xylooligosaccharide refers to an oligosaccharide having a structure in which xylose-derived units are repeated, and typically shows a structure in which xylose-derived units are repeated 2 to 20 times.

The unit derived from a sugar derivative may be a structural unit having a sugar derivative-derived structure in its side chain, or may be a structural unit having a sugar derivative-derived structure in its main chain. When the sugar derivative-derived unit is a structural unit having a sugar derivative-derived structure in its side chain, the sugar derivative-derived unit preferably has a structure represented by general formula (1) described below. In addition, when the unit derived from a sugar derivative is a structural unit having a structure derived from the sugar derivative in the main chain, the unit derived from the sugar derivative may have a structure represented by the general formula (2) described below. preferable. Among these, the unit derived from the sugar derivative preferably has a structure represented by general formula (1) from the viewpoint of preventing the main chain from becoming too long and easily increasing the solubility of the copolymer in an organic solvent. In general formulas (1) and (2), the structure of the sugar derivative is described as a cyclic structure, but the structure of the sugar derivative is not only a cyclic structure but also an open ring structure (chain structure) called an aldose or ketose. ).

The structure represented by general formula (1) will be explained below.

In the general formula (1), s and t are the same or different and represent an integer of 0 or more (preferably 0 to 2).
R ¹ are the same or different and represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, a phosphoryl group, or a sugar derivative group, and multiple R ^1s are the same may be different.
R' represents a hydrogen atom, -OR ¹¹ or -NR ¹² ₂ .
R" represents a hydrogen atom, -OR ¹¹ , -COOR ¹³ or -CH ₂ OR ^13. Here, R ¹¹ represents a hydrogen atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group, and R ¹² represents a hydrogen atom, an alkyl group, a carboxyl group, or an acyl group; multiple R ^12s may be the same or different; R ¹³ represents a hydrogen atom, an alkyl group, an acyl group, an aryl group, or a trimethylsilyl group. Or represents a phosphoryl group.
R ⁵ represents a hydrogen atom or an alkyl group.
X ¹ and Y ¹ are the same or different and represent a single bond or a connecting group.

In general formula (1), R ¹ is the same or different and represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, a phosphoryl group, or a sugar derivative group. and a plurality of R ¹ may be the same or different. Among these, R ¹ is preferably the same or different and is a hydrogen atom or an acyl group having 1 or more and 3 or less carbon atoms. In addition, when the above alkyl group is an alkyl group having a substituent, such an alkyl group includes a sugar derivative group, so the sugar chain moiety may further include a unit derived from a straight chain or branched sugar derivative. may have.

In the present invention, examples of the sugar derivative group include those having the following structure:

(n represents an integer greater than or equal to 1.)
In the above structural formula, the * mark represents the bonding site with the sugar unit of the side chain.

The unit derived from a linear or branched sugar derivative is preferably a sugar derivative having the same structure as the sugar derivative to which it is bound. That is, R" in the structure represented by general formula (1) is a hydrogen atom, -OR ¹¹ , a carboxyl group, and -COOR ¹³ , and the sugar chain moiety (sugar derivative) is further converted into a linear or branched sugar derivative. When the unit has a unit derived from a pentose derivative, it is preferable that the unit has a unit derived from a pentose derivative.Also, R'' in the structure represented by general formula (1) is -CH ₂ OR ¹³ and the sugar chain moiety When (sugar derivative) further has a unit derived from a linear or branched sugar derivative, it is preferable to have a unit derived from a hexose derivative. Further substituents that the hydroxyl group of the unit derived from a straight-chain or branched sugar derivative may have are the same as the range of R ¹ .

In the general formula (1), R ¹ further has a sugar derivative group as at least one alkyl group, that is, it forms a structure in which a plurality of units derived from a sugar derivative derived from a monosaccharide are bonded together. This is preferable from the viewpoint of lowering the solubility in . In this case, the average degree of polymerization of the sugar derivative (meaning the number of bonded sugar derivatives derived from monosaccharides) is preferably 1 or more and 20 or less, more preferably 15 or less, and even more preferably 12 or less. preferable.

When R ¹ is an alkyl group or an acyl group, the number of carbon atoms can be appropriately selected depending on the purpose. For example, the number of carbon atoms is preferably 1 or more, preferably 200 or less, more preferably 100 or less, even more preferably 20 or less, and particularly preferably 4 or less.

Specific examples of R ¹ include, for example, an acetyl group, a propanoyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, a chloroacetyl group, a trifluoroacetyl group, and a cyclopentanecarbonyl group. , acyl groups such as cyclohexanecarbonyl group, benzoyl group, methoxybenzoyl group, chlorobenzoyl group; alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, i-butyl group, t-butyl group, Examples include trimethylsilyl group. Among these, methyl group, ethyl group, acetyl group, propanoyl group, n-butyryl group, isobutyryl group, benzoyl group, and trimethylsilyl group are preferred, and acetyl group and propanoyl group are particularly preferred.

In general formula (1), R' represents a hydrogen atom, -OR ¹¹ or -NR ¹² ₂ . R ¹¹ represents a hydrogen atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group or a phosphoryl group. When R ¹¹ is an alkyl group or an acyl group, the number of carbon atoms thereof can be appropriately selected depending on the purpose. For example, the number of carbon atoms is preferably 1 or more, preferably 200 or less, more preferably 100 or less, even more preferably 20 or less, and particularly preferably 4 or less. Among these, R ¹¹ is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an acyl group having 1 to 3 carbon atoms, or a trimethylsilyl group. Specific examples of R ¹¹ include acetyl group, propanoyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, pivaloyl group, hexanoyl group, octanoyl group, chloroacetyl group, trifluoroacetyl group, and cyclopentanecarbonyl group. , acyl groups such as cyclohexanecarbonyl group, benzoyl group, methoxybenzoyl group, chlorobenzoyl group; alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, i-butyl group, t-butyl group, Examples include trimethylsilyl group. Among these, methyl group, ethyl group, acetyl group, propanoyl group, n-butyryl group, isobutyryl group, benzoyl group, and trimethylsilyl group are preferred, and methyl group, acetyl group, and propanoyl group are particularly preferred.

R ¹² represents a hydrogen atom, an alkyl group, a carboxyl group, or an acyl group, and multiple R ^12s may be the same or different. Among these, R ¹² is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a carboxyl group, or -COCH ₃ .

Preferred structures of R' are -H, -OH, -OAc, -OCOC ₂ H ₅ , -OCOC ₆ H ₅ , -NH ₂ , -NHCOOH, -NHCOCH ₃ , and more preferred structures of R' are -H, --OH, --OAc, --OCOC ₂ H ₅ , and --NH ₂ , and particularly preferred structures of R' are --OH, --OAc, and --OCOC ₂ H ₅ .

In the general formula (1), R" represents a hydrogen atom, -OR ¹¹ , a carboxyl group, -COOR ¹³ or -CH ₂ OR ^13. R ¹³ is a hydrogen atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or Represents a phosphoryl group. When R ¹³ is an alkyl group or an acyl group, the number of carbon atoms can be appropriately selected depending on the purpose. For example, the number of carbon atoms is preferably 1 or more and 200 or less. The number is preferably 100 or less, more preferably 20 or less, and particularly preferably 4 or less. Among these, R ¹³ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms and an acyl group. or a trimethylsilyl group.

Specific examples of R ¹¹ include acetyl group, propanoyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, pivaloyl group, hexanoyl group, octanoyl group, chloroacetyl group, trifluoroacetyl group, and cyclopentanecarbonyl group. , acyl groups such as cyclohexanecarbonyl group, benzoyl group, methoxybenzoyl group, chlorobenzoyl group; alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, i-butyl group, t-butyl group, Examples include trimethylsilyl group. Among these, methyl group, ethyl group, acetyl group, propanoyl group, n-butyryl group, isobutyryl group, benzoyl group, and trimethylsilyl group are preferred, and acetyl group and propanoyl group are particularly preferred.

Preferred structures of R'' are -H, -OAc, -OCOC ₂ H ₅ , -COOH, -COOCH ₃ , -COOC ₂ H ₅ , -CH ₂ OH, -CH ₂ OAc, -CH ₂ OCOC ₂ H ₅ , R'' has a more preferable structure -H, -OAc, -OCOC ₂ H ₅ , -COOH, -CH ₂ OH, -CH ₂ OAc, -CH ₂ OCOC ₂ H ₅ , and a particularly preferable structure of R'' is -H, -CH ₂ OH, -CH ₂ OAc.

In general formula (1), R ⁵ represents a hydrogen atom or an alkyl group. Among these, R ⁵ is preferably a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

In general formula (1), X ¹ and Y ¹ are the same or different and represent a single bond or a connecting group.
When X ¹ is a linking group, examples of X ¹ include groups containing an alkylene group, -O-, -NH ₂ -, carbonyl group, etc., but X ¹ is a single bond or has a carbon number of It is preferably an alkylene group having 1 or more and 6 or less carbon atoms, and more preferably an alkylene group having 1 or more and 3 or less carbon atoms.
When Y ¹ is a linking group, examples of Y ¹ include groups containing an alkylene group, a phenylene group, -O-, -C(=O)O-, and the like. Y ¹ may be a linking group that is a combination of these groups. Among these, Y ¹ is preferably a linking group represented by the following structural formula.

In the above structural formula, the * mark represents the bonding site with the main chain side, and the * mark represents the bonding site with the sugar unit of the side chain.

The structure represented by general formula (2) will be explained below.

In general formula (2), R ²⁰¹ represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group, and multiple R ^201s are the same. It may be different or different.
R' represents a hydrogen atom, -OR ¹¹ or -NR ¹² ₂ .
R" represents a hydrogen atom, -OR ¹¹ , -COOR ¹³ or -CH ₂ OR ^13. Here, R ¹¹ represents a hydrogen atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group, and R ¹² represents a hydrogen atom, an alkyl group, a carboxyl group, or an acyl group; multiple R ^12s may be the same or different; R ¹³ represents a hydrogen atom, an alkyl group, an acyl group, an aryl group, or a trimethylsilyl group. Or represents a phosphoryl group.
The mark * represents a bonding site with any one of the oxygen atoms to which R ²⁰¹ is bonded in place of R ²⁰¹ .

In the general formula (2), the preferred ranges of R ²⁰¹ , R', and R'' are the same as the preferred ranges of R ¹ , R', and R'' in the general formula (1).

Note that R ¹ , R', and R'' from the polymerized polymer can be returned to hydrogen atoms by reduction, and R ¹ and R ¹¹ can be converted to hydrogen. However, even if R ¹ and R ¹¹ are not all reduced, good.

(Unit (b))
The unit (b) is a unit derived from a compound having an antireflection function. In the present invention, the compound having an antireflection function is preferably a compound having a property of strongly absorbing ultraviolet rays, such as an aromatic ring-containing compound.

When the compound having an antireflection function is an aromatic ring-containing compound, the unit (b) is a unit that exhibits hydrophobicity compared to the unit (a), and is therefore a material for the composition for forming the lower layer film. It functions to increase the solubility of the copolymer in organic solvents. That is, undissolved copolymer remains in the composition for forming the lower layer film is suppressed. Furthermore, it is preferable that the unit (b) is a unit derived from an aromatic ring-containing compound from the viewpoint of easily increasing the residual rate of the underlayer film when forming the underlayer film without unnecessarily affecting the crosslinkability. . In this way, when the compound having an antireflection function is an aromatic ring-containing compound, the copolymer contained in the composition for forming the lower layer film has high solubility in organic solvents before film formation, but after film formation, It can exhibit the property of being difficult to dissolve in solvents.

Among these, the unit (b) is preferably a unit derived from a benzene ring-containing compound.

The unit (b) is preferably a unit having a structure represented by the following general formula (3), for example.

In general formula (3), R ⁵ represents a hydrogen atom or an alkyl group.
X ¹ represents a single bond or a connecting group.
R ⁵⁰ represents an organic group or a hydroxyl group.
In general formula (3), n represents an integer of 0 to 5.

In the general formula (3), the preferred ranges of R ⁵ and X ¹ are the same as the preferred ranges of R ⁵ and X ¹ in the general formula (1).

In general formula (3), when R ⁵⁰ is an organic group, R ⁵⁰ is preferably a hydrocarbon group that may have a substituent, and preferably an alkyl group that may have a substituent. preferable. Examples of the hydrocarbon group which may have a substituent include those in which any of the carbon atoms constituting the hydrocarbon group is substituted with an oxygen atom, a silicon atom, a nitrogen atom, a sulfur atom, a halogen, or the like. For example, R ⁵⁰ may be a trimethylsilyl group, a pentamethyldisilyl group, a trifluoromethyl group, or a pentafluoroethyl group.

In the general formula (3), n represents an integer of 0 to 5, preferably an integer of 0 to 3, and particularly preferably 0.

(Unit (c))
Unit (c) is a unit derived from a compound capable of cross-coupling the copolymer. In the present invention, the unit derived from the compound capable of cross-coupling the copolymer is preferably a unit derived from (meth)acrylate.

The unit derived from (meth)acrylate is preferably a unit represented by the following general formula (4), for example.

In general formula (4), R ⁵ represents a hydrogen atom or an alkyl group, and R ⁶⁰ represents an alkyl group that may have a substituent or an aryl group that may have a substituent.

In general formula (4), R ⁵ is preferably a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

The unit (c) preferably has at least one type selected from an alkyl group that may have a substituent and an aryl group that may have a substituent. That is, in the general formula (4), R ⁶⁰ represents an alkyl group which may have a substituent or an aryl group which may have a substituent. Note that R ⁶⁰ may be a combination of the above groups.

Among these, it is preferable that the unit (c) contains an alkyl group which may have a substituent. That is, R ⁶⁰ is preferably an alkyl group which may have a substituent. The number of carbon atoms in the alkyl group is preferably 1 or more and 8 or less, more preferably 1 or more and 5 or less, and even more preferably 1 or more and 3 or less. Note that R ⁶⁰ is also preferably an alkyl group having no substituent, and the above carbon number is the number of carbon atoms excluding the substituent.

Examples of the substituent that the alkyl group having a substituent may include are an isocyanate group, an epoxy group, a (meth)acryloyl group, a hydroxymethylamino group, and an alkoxymethylamino group. Such a substituent may be a group that performs cross-coupling, or may form a cross-coupling structure by self-condensation in the copolymer alone by heating or cross-linking reaction in the presence of a catalyst, etc. . For example, in an alkyl group having an epoxy group as a substituent, a ring-opening reaction of the epoxy group occurs in the presence of an acid catalyst, thereby causing a crosslinking reaction. In this case, the above-mentioned unit (c) can strengthen the formed lower layer film through a crosslinking reaction.

Examples of the alkyl group having a substituent include -CH ₂ -OH, -CH ₂ -O-methyl, -CH ₂ -O-ethyl, -CH ₂ -O-n-propyl, -CH ₂ -O-isopropyl , -CH ₂ -O-n-butyl, -CH ₂ -O-isobutyl, -CH ₂ -O-t-butyl, -CH ₂ -O-(C=O)-methyl, -CH ₂ -O-( C=O)-ethyl, -CH ₂ -O-(C=O)-propyl, -CH ₂ -O-(C=O)-isopropyl, -CH ₂ -O-(C=O)-n-butyl , -CH ₂ -O-(C=O)-isobutyl, -CH ₂ -O-(C=O)-t-butyl, -CH ₂ -ethylene oxide, -C ₂ H ₄ -OH, -C ₂ H ₄ -O-methyl, -C ₂ H ₄ -O-ethyl, -C ₂ H ₄ -O-n-propyl, -C ₂ H ₄ -O-isopropyl, -C ₂ H ₄ -O-n-butyl, - C ₂ H ₄ -O-isobutyl, -C ₂ H ₄ -O-t-butyl, -C ₂ H ₄ -O-(C=O)-methyl, -C ₂ H ₄ -O-(C=O) -Ethyl, -C ₂ H ₄ -O-(C=O)-n-propyl, -C ₂ H ₄ -O-(C=O)-isopropyl, -C ₂ H ₄ -O-(C=O) -n-butyl, -C ₂ H ₄ -O-(C=O)-isobutyl, -C ₂ H ₄ -O-(C=O)-t-butyl, -C ₂ H ₄ -O-(C= O) -CH ₂ -(C=O)-methyl, -C ₂ H ₄ -ethylene oxide, -C ₃ H ₆ -ethylene oxide, -C ₂ H ₄ -O-ethylene oxide, -C ₃ H ₆ -O-ethylene oxide, --C ₄ H ₈ --O-ethylene oxide, --C ₅ H ₁₀ --O-ethylene oxide, --CH ₂ --CH=CH ₂ , --CH ₂ --O-CH=CH ₂ and the like can be mentioned. Further, the alkyl group having a substituent may be a cycloalkyl group or a bridged cyclic cycloalkyl group.

(Unit (d))
The unit (d) is a unit having a functional group that promotes gas permeation to the underlying film.
Examples of the functional group that promotes gas permeation to the lower membrane include those that are bulky and have the function of lowering membrane density, such as cycloalkyl groups and long-chain alkyl groups. Examples of functional groups that promote gas permeation to the lower membrane include C3 to C12 cycloalkyl groups, C10 or higher aliphatic alkyl groups (preferably C10 to C25 aliphatic alkyl groups), and alkoxypolyalkoxycarbonyl groups (preferably C10 to C25 aliphatic alkyl groups). (C1-C25 alkoxy-polyC1-C25 alkoxycarbonyl group, etc.). In the present invention, C10 or more aliphatic alcohol (for example, C10 to C25 aliphatic alcohol) or C10 or more alkoxy polyalkylene glycol (for example, C1 to C20 alkoxy-polyoxy C1 to C20 alkylene glycol (polyoxy C1 to C20 alkylene) The number of repetitions of oxyC1-C20 alkylene is not limited, but may be, for example, 1 to 20 times, preferably 1 to 5 times), etc.) and (meth)acrylic acid. is preferred. As a result, after the lower layer film is formed, the linear bulky functional groups form many voids, thereby reducing the film density and promoting gas permeation. Furthermore, by controlling the polarity using a functional group having an oxygen atom, it is possible to further strengthen the adhesion between the lower layer film and the film in contact with it.

According to the present invention, by combining the unit (d) in addition to the unit (a), the unit (b), and the unit (c), the metal gas can be further diffused into the lower layer film. Thereby, the amount of metal introduced can be increased and etching processability can be improved.

(Content rate)
The content of unit (a) in the copolymer (content of sugar derivative units) is preferably 1% by mass or more and 95% by mass or less, and 5% by mass or more and 90% by mass or less, based on the total mass of the copolymer. It is more preferably at least 10% by mass and at most 85% by mass, particularly preferably at least 20% by mass and at most 80% by mass.

Here, the content of sugar derivative units in the copolymer can be determined, for example, from ¹ H-NMR and the weight average molecular weight of the copolymer. Specifically, it can be calculated using the following formula.
Content of unit (a) (mass%) = mass of unit (a) x number of units (a) (number of monomers) / weight average molecular weight of copolymer

Further, the content of the unit (b) in the copolymer is preferably 1% by mass or more and 95% by mass or less, more preferably 5% by mass or more and 90% by mass or less, based on the total mass of the copolymer. It is more preferably 10% by mass or more and 85% by mass or less. The content of the unit (c) in the copolymer is preferably 1% by mass or more and 95% by mass or less, more preferably 5% by mass or more and 90% by mass or less, and 10% by mass or less, based on the total mass of the copolymer. % or more and 85% by mass or less is more preferable. The content of the unit (d) in the copolymer is preferably 1% by mass or more and 95% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and 7% by mass or less, based on the total mass of the copolymer. % or more and 15% by mass or less is more preferable.
In addition, the content rate of each unit can also be calculated by the same method as the calculation of the content rate of unit (a).

Furthermore, the lower limit of the ratio (mass ratio) between the content of units (a) and the content of units (b) in the copolymer is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, based on 100 parts by mass of the former. It is preferably 13 parts by mass or more, and more preferably 13 parts by mass or more. The upper limit of the ratio (mass ratio) between the content of units (a) and the content of units (b) in the copolymer is 100 parts by mass of the former,
It is preferably 22 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 17 parts by mass or less.
The lower limit of the ratio (mass ratio) between the content of units (a) and the content of units (c) in the copolymer is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, with respect to 100 parts by mass of the former, More preferably 13 parts by mass or more. The upper limit of the ratio (mass ratio) between the content of units (a) and the content of units (c) in the copolymer is preferably 22 parts by mass or less, more preferably 20 parts by mass or less, with respect to 100 parts by mass of the former. More preferably, it is 17 parts by mass or less.
The lower limit of the ratio (mass ratio) between the content of units (a) and the content of units (d) in the copolymer is preferably 10 parts by mass or more, more preferably 12 parts by mass or more, based on 100 parts by mass of the former. More preferably 13 parts by mass or more. The upper limit of the ratio (mass ratio) between the content of units (d) and the content of units (d) in the copolymer is preferably 22 parts by mass or less, more preferably 20 parts by mass or less, per 100 parts by mass of the former. More preferably, it is 17 parts by mass or less.

(Other constituent units)
The copolymer may have other structural units in addition to the above structural units. Other structural units include, for example, lactic acid-derived units, siloxane bond-containing units, amide bond-containing units, urea bond-containing units, and the like.
(Weight average molecular weight of copolymer)
The weight average molecular weight (Mw) of the copolymer is preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. Further, the weight average molecular weight (Mw) of the copolymer is preferably 1 million or less, more preferably 500,000 or less, even more preferably 300,000 or less, and even more preferably 250,000 or less. . It is preferable that the weight average molecular weight (Mw) of the copolymer is within the above range from the viewpoint of the persistence of the underlayer film after coating. The weight average molecular weight (Mw) of the copolymer is a value measured in terms of polystyrene by GPC.

The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw/Mn) of the copolymer is preferably 1 or more. Further, Mw/Mn is preferably 52 or less, more preferably 10 or less, even more preferably 8 or less, even more preferably 4 or less, and particularly preferably 3 or less. . It is preferable that Mw/Mn be within the above range from the viewpoint of the persistence of the underlayer film after coating.

Note that the weight average molecular weight and number average molecular weight in the present invention are values measured by gel permulation chromatography (GPC) under the following conditions.

[GPC measurement conditions]
Measuring device: “HLC-8220 GPC” manufactured by Tosoh Corporation
Column: Guard column “HHR-H” manufactured by Tosoh Corporation (6.0 mm I.D. x 4 cm)
+ “TSK-GEL GMHHR-N” manufactured by Tosoh Corporation (7.8mm I.D. x 30cm)
+ “TSK-GEL GMHHR-N” manufactured by Tosoh Corporation (7.8mm I.D. x 30cm)
+ “TSK-GEL GMHHR-N” manufactured by Tosoh Corporation (7.8mm I.D. x 30cm)
+ “TSK-GEL GMHHR-N” manufactured by Tosoh Corporation (7.8mm I.D. x 30cm)
Detector: Evaporative light scattering detector (“ELSD2000” manufactured by Alltec Japan Co., Ltd.)
Data processing: Tosoh Corporation "GPC-8020 Model II data analysis version 4.30"
Measurement conditions: Column temperature 40℃
Developing solvent Tetrahydrofuran (THF)
Flow rate 1.0 ml/min Sample: 1.0 mass% tetrahydrofuran solution in terms of solid content filtered through a microfilter (5 μl)
Standard sample: The following monodisperse polystyrene with a known molecular weight was used in accordance with the measurement manual of the above-mentioned "GPC-8020 Model II Data Analysis Version 4.30."

(Monodisperse polystyrene)
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
"F-288" manufactured by Tosoh Corporation
"F-550" manufactured by Tosoh Corporation

(Solubility of copolymer)
The solubility of the copolymer in at least one selected from PGMEA, PGME, THF, butyl acetate, anisole, cyclohexanone, ethyl lactate, N-methylpyrrolidone, γ-butyrolactone and DMF is preferably 1% by mass or more, It is more preferably 2% by mass or more, particularly preferably 3% by mass or more, and even more preferably 4% by mass or more. The upper limit of the solubility of the copolymer in the organic solvent is not particularly limited, but may be, for example, 40% by mass. The above solubility is the solubility in at least one selected from PGMEA, PGME, THF, butyl acetate, anisole, cyclohexanone, ethyl lactate, N-methylpyrrolidone, γ-butyrolactone, and DMF, and the copolymer used in the present invention It is preferable that the solubility in any of the above-mentioned organic solvents is at least a certain value.

The solubility of a copolymer is measured by gradually adding PGMEA, PGME, THF, butyl acetate, anisole, cyclohexanone, ethyl lactate, N-methylpyrrolidone, γ-butyrolactone, or DMF to a predetermined amount of the copolymer and stirring to dissolve the copolymer. Record the amount of organic solvent added. A magnetic stirrer or the like may be used for stirring. Then, calculate the solubility using the following formula:
Solubility (mass%) = mass of copolymer/amount of organic solvent when dissolved x 100

In order to make the solubility of the copolymer in at least one of PGMEA, PGME, THF, butyl acetate, anisole, cyclohexanone, ethyl lactate, N-methylpyrrolidone, γ-butyrolactone, and DMF within the above range, for example, the unit ( It is conceivable that b) is a unit derived from an aromatic ring-containing compound. Furthermore, in order to keep the solubility within the above range, it is possible to control the content of units derived from sugar derivatives. Specifically, by making the unit (b) a unit derived from an aromatic ring-containing compound, and by controlling the content of units derived from a sugar derivative (unit (a)) in the copolymer to a certain value or less, Solubility in organic solvents can be more effectively increased.

<Copolymer synthesis method>
The copolymer can be synthesized using known polymerization methods such as free radical polymerization, living radical polymerization, living anion polymerization, and atom transfer radical polymerization. For example, in the case of living free radical polymerization, a polymerization initiator such as AIBN (α, α'-azobisisobutyronitrile) is used to form units (a), (b), (c), and (d). A copolymer can be obtained by reacting each with its constituent monomers. In the case of living anionic polymerization, a copolymer can be obtained by reacting the monomers constituting each of the units (a), (b), (c) and (d) with butyllithium in the presence of lithium chloride. can. Although this example shows examples of synthesis using free radical polymerization, living anion polymerization, and living radical polymerization, the present invention is not limited to these, and synthesis may be performed as appropriate using each of the above synthesis methods or known synthesis methods. be able to.

Commercially available products may be used as the copolymer and its raw materials. Examples include homopolymers, random polymers, and block copolymers such as P9128D-SMMAran, P9128C-SMMAran, Poly (methyl methacrylate), P9130C-SMMAran, P7040-SMMAran, and P2405-SMMA manufactured by Polymer Source. Further, using these polymers, synthesis can be carried out as appropriate using known synthesis methods.

The polymerization part a as described above may be obtained by synthesis, but it may also be obtained by a combination of extraction steps from lignocellulose derived from woody plants or herbaceous plants. When employing a method of extraction from lignocellulose derived from woody plants or herbaceous plants to obtain the sugar derivative portion of polymerization portion a, use the extraction method described in JP-A No. 2012-100546, etc. be able to.

Xylan can be extracted, for example, by the method disclosed in JP-A-2012-180424.
Cellulose can be extracted, for example, by the method disclosed in JP-A No. 2014-148629.

The polymerization part a is preferably used by modifying the OH group of the sugar part by acetylation, halogenation, etc. using the above extraction method. For example, when introducing an acetyl group, an acetylated sugar derivative moiety can be obtained by reacting with acetic anhydride.

The polymerization part b and the polymerization part c may be formed by synthesis, or commercially available products may be used. When polymerizing the polymerization part b and the polymerization part c, a known synthesis method can be employed. In addition, when using a commercially available product, for example, Amino-terminated PS (Mw=12300Da, Mw/Mn=1.02, manufactured by Polymer Source Co., Ltd.) can be used.

<Organic solvent>
The composition for forming a lower layer film of the present invention contains an organic solvent. However, the composition for forming the lower layer film may further contain an aqueous solvent such as water or various aqueous solutions in addition to the organic solvent. Examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, sulfur-containing solvents, amide solvents, ester solvents, and hydrocarbon solvents. These solvents may be used alone or in combination of two or more.

Examples of alcoholic solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, tert-butanol, n-pentanol, i-pentanol, and 2-methylbutanol. , sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethyl Hexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furfuryl alcohol , phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol, etc.; ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentane Diol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene Examples include glycol, 1H,1H-trifluoroethanol, 1H,1H-pentafluoropropanol, 6-(perfluoroethyl)hexanol, and the like.

In addition, as polyhydric alcohol partial ether solvents, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2 - Ethyl butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene Examples include glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and the like.

Examples of the ether solvent include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether, and tetrahydrofuran (THF).

Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, and methyl-n-butyl ketone. -hexylketone, di-i-butylketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonyl acetone, acetophenone, furfural and the like.

Examples of the sulfur-containing solvent include dimethyl sulfoxide.

Examples of amide solvents include N,N'-dimethylimidazolidinone, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, and N,N-dimethylacetamide. , N-methylpropionamide, N-methylpyrrolidone and the like.

Examples of ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, and acetic acid. sec-butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, acetate Methyl acetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl acetate, diethylene glycol monomethyl acetate, diethylene glycol monoethyl acetate, diethylene glycol mono-n-butyl acetate, propylene glycol monomethyl acetate (PGMEA), propylene acetate Glycol monoethyl ether, propylene glycol monopropyl acetate, propylene glycol monobutyl ether, dipropylene glycol monomethyl acetate, dipropylene glycol monoethyl acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-propionate Butyl, i-amyl propionate, methyl 3-methoxypropionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate , diethyl phthalate, and the like.

Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, 2,2,4-trimethylpentane, n-octane, i-octane, cyclohexane, methylcyclohexane, etc.; aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, i-propylbenzene, diethylbenzene, Examples include i-butylbenzene, triethylbenzene, di-i-propylbenzene, n-amylnaphthalene, and anisole.

Among these, propylene glycol monomethyl ether acetate (PGMEA), N,N-dimethylformamide (DMF), propylene glycol monomethyl ether (PGME), anisole, ethanol, methanol, acetone, methyl ethyl ketone, hexane, tetrahydrofuran (THF), dimethyl sulfoxide. (DMSO), 1H,1H-trifluoroethanol, 1H,1H-pentafluoropropanol, 6-(perfluoroethyl)hexanol, ethyl acetate, propyl acetate, butyl acetate, cyclohexanone, furfural, N-methylpyrrolidone, γ-butyrolactone is more preferred, PGMEA, PGME, THF, butyl acetate, anisole, cyclohexanone, N-methylpyrrolidone, γ-butyrolactone or DMF is even more preferred, and PGMEA is even more preferred. These solvents may be used alone or in combination of two or more.

The content of the organic solvent is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more, based on the total mass of the composition for forming the lower layer film. preferable. Further, the content of the organic solvent is preferably 99.9% by mass or less, more preferably 99% by mass or less. By controlling the content of the organic solvent within the above range, the coating properties of the composition for forming the lower layer film can be improved.

<Optional ingredients>
The composition for forming a lower layer film of the present invention may contain optional components as described below.

<<Crosslinkable compound>>
The composition for forming a lower layer film of the present invention may further contain a crosslinkable compound. Due to this crosslinking reaction, the formed lower layer film becomes strong, and etching processability can be improved more effectively.

The crosslinking compound is not particularly limited, but a crosslinking compound having at least two crosslinking substituents is preferably used. A crosslinking compound is a compound having two or more, for example 2 to 6, at least one crosslinking substituent selected from isocyanate groups, epoxy groups, (meth)acryloyl groups, hydroxymethylamino groups, and alkoxymethylamino groups. It can be used as

Examples of the crosslinkable compound include nitrogen-containing compounds substituted with a hydroxymethyl group, an alkoxymethyl group, an epoxy group, or a (meth)acryloyl group, and having two or more nitrogen atoms, for example, 2 to 6 nitrogen atoms. Examples include compounds. Among these, the crosslinkable compound is preferably a nitrogen-containing compound having a nitrogen atom substituted with a group such as a hydroxymethyl group, a methoxymethyl group, an ethoxymethyl group, a butoxymethyl group, or a hexyloxymethyl group. Specifically, hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4,6-tetrakis(butoxymethyl)glycoluril, 1,3,4,6-tetrakis(hydroxymethyl)glycoluril, 1,3 -bis(hydroxymethyl)urea, 1,1,3,3-tetrakis(butoxymethyl)urea, 1,1,3,3-tetrakis(methoxymethyl)urea, 1,3-bis(hydroxymethyl)-4, Nitrogen-containing compounds such as 5-dihydroxy-2-imidazolinone, 1,3-bis(methoxymethyl)-4,5-dimethoxy-2-imidazolinone, dicyclohexylcarbodiimide, diisopropylcarbodiimide, di-tert-butylcarbodiimide, piperazine, etc. can be mentioned.

In addition, as crosslinking compounds, methoxymethyl type melamine compounds (trade names Cymel 300, Cymel 301, Cymel 303, Cymel 350) manufactured by Mitsui Cytec Co., Ltd., butoxymethyl type melamine compounds (trade names Mycoat 506, Mycoat 508) are used. ), glycoluril compounds (product name Cymel 1170, Powder Link 1174), methylated urea resin (product name UFR65), butylated urea resin (product name UFR300, U-VAN10S60, U-VAN10R, U-VAN11HV), Dainippon Co., Ltd. Urea/formaldehyde resin manufactured by Ink Kagaku Kogyo Co., Ltd. (trade name: Beckamine J-300S, Beckamine P-955, Beckamine N), (meth)acrylate monomer manufactured by ARKEMA (trade name: SR209, SR272), epoxy acrylate oligomer (CN110NS) ), neopentyl glycol diglycidyl ether manufactured by Tokyo Kasei Co., Ltd., and other commercially available compounds can be used. In addition, as a crosslinkable compound, an acrylamide compound or methacrylamide substituted with a hydroxymethyl group or an alkoxymethyl group such as N-hydroxymethylacrylamide, N-methoxymethylmethacrylamide, N-ethoxymethylacrylamide, N-butoxymethylmethacrylamide, etc. Polymers made using amide compounds can be used.
As the crosslinking compound, only one type of compound can be used, or two or more types of compounds can be used in combination.

These crosslinking compounds can cause a crosslinking reaction by self-condensation. It can also cause a crosslinking reaction with the structural units contained in the polymer.

<<Catalyst>>
The composition for forming the lower layer film contains p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, and dodecylbenzene as catalysts to promote the crosslinking reaction. Acid compounds such as ammonium sulfonate and hydroxybenzoic acid can be added. Acid compounds include p-toluenesulfonic acid, pyridinium-p-toluenesulfonic acid, sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, pyridinium-1-naphthalene. Aromatic sulfonic acid compounds such as sulfonic acid can be mentioned. Also, 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, phenyl- Acid generators such as bis(trichloromethyl)-s-triazine, benzointosylate, N-hydroxysuccinimide trifluoromethanesulfonate, bis-(t-butylsulfonyl)diazomethane, and cyclohexylsulfonyldiazomethane can be added.

<<Light antireflection agent>>
The composition for forming a lower layer film of the present invention may further contain a light antireflection agent. Examples of the light antireflection agent include compounds having light-absorbing properties. Examples of light-absorbing compounds include compounds that have a high absorption ability for light in the photosensitive wavelength range of the photosensitive component in the photoresist provided on the lower layer film, such as benzophenone compounds, benzotriazole, etc. compounds, azo compounds, naphthalene compounds, anthracene compounds, anthraquinone compounds, triazine compounds and the like. Examples of the polymer include polyester, polyimide, polystyrene, novolak resin, polyacetal, and acrylic polymer. Examples of the polymer having a light-absorbing group connected by a chemical bond include polymers having a light-absorbing aromatic ring structure such as an anthracene ring, a naphthalene ring, a benzene ring, a quinoline ring, a quinoxaline ring, and a thiazole ring.

＜＜Other ingredients＞＞
The composition for forming a lower layer film may further contain an ionic liquid, a surfactant, and the like. By containing an ionic liquid in the composition for forming a lower layer film, the compatibility between the copolymer and the organic solvent can be improved.
By containing a surfactant in the composition for forming a lower layer film, the applicability of the composition for forming a lower layer film onto a substrate can be improved. Moreover, when forming a pattern using the composition for forming an underlayer film, the coatability of a resist composition or the like applied subsequent to the composition for forming an underlayer film can be improved. Preferred surfactants include, for example, nonionic surfactants, fluorine surfactants, and silicone surfactants.
In addition, arbitrary materials such as known rheology modifiers and adhesion aids may be included in the composition for forming the underlayer film.

Note that the content of the above-mentioned optional components is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the composition for forming the lower layer film.

(lower layer film)
The present invention may also relate to a lower layer film formed from the above-described composition for forming a lower layer film. The lower layer film is a layer provided on a substrate such as a silicon wafer. Note that in this specification, a lower layer film processed into a pattern shape is also referred to as a protective film, but such a protective film is also included in the lower layer film. That is, the lower layer film includes a layered film before patterning and an intermittent film after patterning.

FIG. 1A shows a laminate in which a lower film 20 is formed on a substrate 10. As shown in FIG. Although not shown, the lower layer film is preferably a layer provided under the resist film, for example. That is, the lower layer film is preferably a layer provided between the substrate and the resist film. The lower layer film is a layer for preventing interaction between the substrate and the resist film, a layer for preventing the adverse effects on the substrate of materials used for the resist film or substances generated during exposure of the resist film, and a layer for preventing the material used for the resist film or substances generated during exposure of the resist film from adversely affecting the substrate. It can also function as a layer for preventing substances generated from the substrate from diffusing into the resist film, and a barrier layer for reducing the poisoning effect of the resist film by the semiconductor substrate dielectric layer. Further, the lower layer film also functions as a planarizing material for planarizing the substrate surface.

As shown in FIG. 1B, at least a portion of the lower film 20 is removed so as to form a pattern desired to be formed on the substrate 10. For example, by laminating a resist film on the lower layer film 20 and performing exposure and development processing, a pattern shape as shown in FIG. 1(b) can be formed. After that, the exposed substrate 10 is exposed to chlorine gas, boron trichloride, methane tetrafluoride gas, methane trifluoride gas, ethane hexafluoride gas, propane octafluoride gas, sulfur hexafluoride gas, argon gas, oxygen gas. Pattern formation is performed by performing reactive ion etching such as inductively coupled plasma using helium gas or the like, and a pattern as shown in FIG. 1C is formed on the substrate 10.

Note that it is also possible to form a self-assembled film or a resist film from the composition for forming a lower layer film of the present invention. When the composition for forming a lower layer film contains a block copolymer, the block copolymer is applied onto a substrate and subjected to annealing to form a film having a phase-separated structure due to self-organization (self-assembled film). A pattern can be formed by removing some of the phases in the self-assembled film. In addition, when forming a resist film from the composition for forming an underlayer film, the resist film formed from the composition for forming an underlayer film is irradiated with short-wavelength deep ultraviolet rays through a mask on which a circuit pattern is drawn. The pattern is transferred by changing the quality of the resist film in the exposed areas (exposure). Thereafter, a pattern can be formed by dissolving the exposed portion with a developer.

The thickness of the lower layer film can be adjusted as appropriate depending on the application, but for example, it is preferably 1 nm or more and 20,000 nm or less, more preferably 1 nm or more and 10,000 nm or less, and even more preferably 1 nm or more and 5,000 nm or less. It is particularly preferable that the thickness is 1 nm or more and 3000 nm or less.

The lower layer film is preferably a film into which a metal is introduced, and as a result, preferably contains a metal. The metal content of the lower layer film is preferably 5 at% or more, more preferably 8 at% or more, even more preferably 10 at% or more, and even more preferably 15 at% or more. The metal content can be calculated, for example, by the following method. First, the lower layer film is placed in an ALD (atomic layer deposition apparatus), into which Al(CH ₃ ) ₃ gas is introduced at 95° C., and then water vapor is introduced therein. By repeating this operation three times, Al is introduced into the lower layer film. EDX analysis (energy dispersive X-ray analysis) was performed on the lower layer film after Al introduction using an electron microscope JSM7800F (manufactured by JEOL Ltd.) to calculate the ratio of Al components (Al content), which was calculated as the metal content. shall be.

(Pattern formation method)
The present invention also relates to a pattern forming method using the above-mentioned composition for forming an underlayer film. The pattern forming method of the present invention includes a step of forming a lower layer film using the above-described composition for forming a lower layer film.

The pattern forming method preferably includes a step of introducing a metal into the composition for forming the lower layer film and/or the lower layer film. Among these, it is more preferable that the pattern forming method includes a step of introducing metal into the lower layer film.

Preferably, the patterning method includes a lithography process before the step of introducing metal. The lithography process preferably includes a step of forming a resist film on the lower layer film, and a step of removing a portion of the resist film and the lower layer film to form a pattern.

Note that the method may further include a step of forming a guide pattern on the substrate between the step of forming the lower layer film and the step of forming the resist film. Further, the step of forming a guide pattern on the substrate may be provided before the step of applying the composition for forming a lower layer film. The step of forming a guide pattern is a step of forming a pre-pattern on the lower layer film formed in the step of applying the composition for forming the lower layer film.

Preferably, the pattern forming method includes a step of processing a semiconductor substrate using the above-described pattern as a protective film. Such a process is called an etching process.

<Step of forming lower layer film>
The pattern forming method of the present invention preferably includes a step of forming a lower layer film. The step of forming a lower layer film is a step of applying a composition for forming a lower layer film onto a substrate to form a lower layer film.

Examples of the substrate include glass, silicon, SiO ₂ , SiN, GaN, and AlN substrates. Further, a substrate made of an organic material such as PET, PE, PEO, PS, cycloolefin polymer, polylactic acid, or cellulose nanofiber may also be used.

The substrate and the lower film are preferably laminated in this order so that adjacent layers are in direct contact with each other, but other layers may be provided between each layer. For example, an anchor layer may be provided between the substrate and the underlying film. The anchor layer is a layer that controls the wettability of the substrate, and is a layer that increases the adhesion between the substrate and the underlying film. Further, a plurality of layers made of different materials may be sandwiched between the substrate and the lower layer film. These materials are not particularly specified, but include, for example, SiO ₂ , SiN, Al ₂ O ₃ , AlN, GaN, GaAs, W, SOC, SOG, Cr, Mo, MoSi, Ta, Ni, Ru, Examples include inorganic materials such as TaBN and Ag, and organic materials such as commercially available adhesives.

The method for applying the composition for forming the lower layer film is not particularly limited, but for example, the composition for forming the lower layer film can be applied onto the substrate by a known method such as a spin coating method. Further, after applying the composition for forming a lower layer film, the composition for forming a lower layer film may be cured by exposure and/or heating to form a lower layer film. Examples of the radiation used for this exposure include visible light, ultraviolet rays, far ultraviolet rays, X-rays, electron beams, gamma rays, molecular beams, and ion beams. Further, the temperature at which the coating film is heated is not particularly limited, but preferably 90°C or more and 550°C or less.

It is preferable to provide a step of cleaning the substrate before applying the underlayer film forming composition to the substrate. By cleaning the substrate surface, the coating properties of the composition for forming the lower layer film are improved. As the cleaning treatment method, conventionally known methods can be used, such as oxygen plasma treatment, ozone oxidation treatment, acid-alkali treatment, chemical modification treatment, and the like.

After forming the lower layer film, it is preferable that heat treatment (baking) is performed using the lower layer film forming composition to form a layer of the lower layer film. In the present invention, the heat treatment is preferably carried out in the atmosphere at a relatively low temperature.
It is preferable that the conditions for the heat treatment are appropriately selected from among a heat treatment temperature of 60° C. to 350° C. and a heat treatment time of 0.3 to 60 minutes. Among these, the heat treatment temperature is more preferably 130° C. to 250° C., the heat treatment time is more preferably 0.5 to 30 minutes, and even more preferably 0.5 to 5 minutes. .

After forming the lower layer film, if necessary, the lower layer film may be rinsed using a rinsing liquid such as a solvent. The rinsing process removes uncrosslinked portions and the like in the lower layer film, so that the formability of a film formed on the lower layer film, such as a resist, can be improved.
The rinsing liquid may be any solvent as long as it can dissolve the uncrosslinked portion, and may be a solvent such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), ethyl lactate (EL), or cyclohexanone, or a commercially available rinsing liquid. Thinner liquid etc. can be used.
Further, after cleaning, post-baking may be performed in order to volatilize the rinsing liquid. The temperature conditions for this post-bake are preferably 80°C or more and 300°C or less, and the baking time is preferably 30 seconds or more and 600 seconds or less.

Since the lower layer film formed from the lower layer film forming composition of the present invention has the property of absorbing ultraviolet rays, it can also function as a light antireflection film. Note that, as described later, a light antireflection film may be formed separately from the lower layer film.

When using the underlayer film as an antireflection film in a lithography process using a KrF excimer laser (wavelength 248 nm), the composition for forming the underlayer film may contain a component having an anthracene ring or a naphthalene ring. preferable. When the underlayer film is used as an antireflection film in a lithography process using an ArF excimer laser (wavelength: 193 nm), it is preferable that the composition for forming the underlayer film contains a compound having a benzene ring. . In addition, when the underlayer film is used as an antireflection film in a lithography process using an F2 excimer laser (wavelength: 157 nm), the composition for forming the underlayer film contains a compound having a bromine atom or an iodine atom. It is preferable.

Furthermore, the lower layer film includes a layer for preventing interaction between the substrate and the photoresist, a layer for preventing the material used for the photoresist or a substance generated during exposure of the photoresist from adversely affecting the substrate, and It can also function as a layer to prevent substances generated from the substrate during firing from diffusing into the overlying photoresist, and a barrier layer to reduce the poisoning effect of the photoresist layer by the semiconductor substrate dielectric layer. Further, the lower layer film formed from the lower layer film forming composition also functions as a flattening material for flattening the substrate surface.

<Step of forming an anti-reflection film>
When the pattern forming method is used in a semiconductor manufacturing method, a step of forming an organic or inorganic light antireflection film may be provided before and after forming the lower layer film on the substrate. In this case, an anti-reflection film may be further provided in addition to the lower layer film.

The composition for a light antireflection film used for forming the light antireflection film is not particularly limited, and can be arbitrarily selected from those commonly used in lithography processes. Further, the antireflection film can be formed by a commonly used method, for example, coating with a spinner or coater and baking. Examples of compositions for antireflection films include compositions containing a light-absorbing compound and a polymer as main components, compositions containing a cross-linking agent and a polymer having light-absorbing groups connected by chemical bonds, and light-absorbing compounds. Examples include compositions containing a crosslinking agent as a main component, and compositions containing a light-absorbing polymer crosslinking agent as a main component. These antireflection film compositions can also contain an acid component, an acid generator component, a rheology modifier, etc., as necessary. As the light-absorbing compound, any compound can be used as long as it has a high absorption ability for light in the photosensitive wavelength range of the photosensitive component in the photoresist provided on the antireflection film, such as benzophenone compounds, Examples include benzotriazole compounds, azo compounds, naphthalene compounds, anthracene compounds, anthraquinone compounds, and triazine compounds. Examples of the polymer include polyester, polyimide, polystyrene, novolak resin, polyacetal, and acrylic polymer. Examples of polymers having light-absorbing groups connected by chemical bonds include polymers having light-absorbing aromatic ring structures such as anthracene rings, naphthalene rings, benzene rings, quinoline rings, quinoxaline rings, and thiazole rings.

Further, the substrate to which the composition for forming a lower layer film of the present invention is applied may have an inorganic anti-reflection film formed by CVD or the like on its surface, and the lower layer film is applied thereon. It can also be formed.

<Step of forming a resist film>
Preferably, the step of forming a resist film is a step of forming a layer of photoresist. The formation of the photoresist layer is not particularly limited, but any known method can be employed. For example, a photoresist layer can be formed by applying a photoresist composition solution onto the underlying film and baking it.

The photoresist coated and formed on the lower layer film is not particularly limited as long as it is sensitive to the light used for exposure. Furthermore, either a negative photoresist or a positive photoresist can be used. A positive photoresist consisting of a novolac resin and 1,2-naphthoquinonediazide sulfonic acid ester, a chemically amplified photoresist consisting of a binder having a group that decomposes with acid and increases the rate of alkali dissolution, and a photoacid generator; A chemically amplified photoresist consisting of a low-molecular compound that decomposes to increase the alkali dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, a binder having a group that decomposes with an acid to increase the alkali dissolution rate, and an acid. There are chemically amplified photoresists that are made of a photoacid generator and a low-molecular compound that decomposes to increase the alkali dissolution rate of the photoresist. Examples include APEX-E (trade name) manufactured by Shipley Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. In addition, the composition for forming a lower layer film of the present invention can also be used as a composition for forming a resist film.

Preferably, the step of forming the resist film includes a step of exposing the resist film to light through a predetermined mask. For exposure, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F2 excimer laser (wavelength 157 nm), EUV (extreme ultraviolet light) (13 nm), etc. can be used. After exposure, post-exposure bake can be performed as needed. The post-exposure heating is preferably carried out at a heating temperature of 70° C. to 150° C. and a heating time of 0.3 to 10 minutes.

Preferably, the step of forming the resist film includes a step of developing with a developer. In this way, for example, if a positive photoresist is used, the exposed portions of the photoresist are removed and a photoresist pattern is formed. Examples of developing solutions include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline, ethanolamine, propylamine, Examples include alkaline aqueous solutions such as amine aqueous solutions such as ethylenediamine. Furthermore, surfactants and the like can also be added to these developers. The conditions for development are appropriately selected from a temperature of 5 to 50° C. and a time of 10 to 300 seconds.

Furthermore, the resist film can also be formed using nanoimprint lithography in addition to the photolithography described above. In the case of nanoimprint lithography, it can be formed by applying a photocurable nanoimprint resist, pressing a mold in which a pattern has been formed in advance against the resist, and irradiating it with light such as UV. Further, the resist film may be a self-organized film.

<Pattern formation process of lower layer film>
In the pattern forming method, it is preferable that a portion of the underlying film is removed using the resist film pattern formed in the above-described resist film forming step as a protective film. Such a process is called a pattern forming process for the lower layer film.

Methods for removing a portion of the lower layer film include known methods such as reactive ion etching (RIE) such as chemical dry etching and chemical wet etching (wet development), and physical etching such as sputter etching and ion beam etching. There are several methods. The lower layer film can be removed using, for example, tetrafluoromethane, perfluorocyclobutane (C ₄ F ₈ ), perfluoropropane (C ₃ F ₈ ), perfluoroethane (C ₂ F ₆ ), boron trichloride, trifluoromethane. It is preferable to perform dry etching using a gas such as , trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, chlorine, helium, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, and chlorine trifluoride.

Further, a chemical wet etching process can also be employed as a process for removing a portion of the lower layer film. Wet etching methods include, for example, a method of reacting with acetic acid, a method of reacting with a mixed solution of alcohol and water such as ethanol or i-propanol, and a method of treating with acetic acid or alcohol after irradiation with UV light or EB light. Examples include processing methods.

<Process of introducing metal>
Preferably, the pattern forming method further includes a step of introducing a metal into the underlying film, such as a SIS method (Sequential Infiltration Synthesis). The metals to be introduced include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Examples include Hg, Tl, Pb, Bi, Po, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Such a process can be performed, for example, by the method described in Journal of Photopolymer Science and Technology Volume 29, Number 5 (2016) 653-657. Further, in the step of introducing metal, a method using a metal complex gas, a method of applying a solution containing a metal, or a method using ion implantation can be adopted.

The step of introducing metal is preferably provided after forming the lower layer film. For example, after forming the lower layer film, it is preferable to perform a step of forming a resist film, a patterning step of the lower layer film, a step of introducing metal, and an etching step in this order. However, the step of introducing metal may be provided before the step of forming the lower layer film. That is, the target to which the metal is introduced is not limited to the lower layer film, but may be the composition for forming the lower layer film.

<Etching process>
In the pattern forming method, it is preferable that the semiconductor substrate be processed using the resist film pattern formed in the above-described resist film forming step as a protective film. Such a process is called an etching process.

Methods for processing the semiconductor substrate in the etching process include known methods such as reactive ion etching (RIE) such as chemical dry etching and chemical wet etching (wet development), and physical etching such as sputter etching and ion beam etching. There are several methods. Processing of semiconductor substrates can be carried out using, for example, tetrafluoromethane, perfluorocyclobutane (C ₄ F ₈ ), perfluoropropane (C ₃ F ₈ ), trifluoromethane, carbon monoxide, argon, helium, oxygen, nitrogen, chlorine, It is preferable to perform dry etching using a gas such as sulfur fluoride, difluoromethane, nitrogen trifluoride, or chlorine trifluoride.

Further, in the etching process, a chemical wet etching process can also be adopted. Wet etching methods include, for example, a method of reacting with acetic acid, a method of reacting with a mixed solution of alcohol and water such as ethanol or i-propanol, and a method of treating with acetic acid or alcohol after irradiation with UV light or EB light. Examples include processing methods.

<Use of pattern>
The pattern formed as described above is also preferably used as a guide for pattern formation using a self-assembled pattern forming material (DSA (Directed Self Assembly lithography)). It is also preferable to use it as a mold for nanoimprint lithography.

Further, the pattern forming method can be applied to various manufacturing methods. For example, the pattern forming method may be used in a semiconductor manufacturing process. As an example of a method for manufacturing a semiconductor, it is preferable to include a step of forming a pattern on a semiconductor substrate by the pattern forming method described above.

EXAMPLES The features of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.
In addition, l, m, n, p, and r in the copolymer examples indicate the number of structural units contained in the copolymer.

[Preparation of sugar]
Xylooligosaccharides and xylose were obtained by extraction from wood pulp with reference to JP 2012-100546A.
D-(+) glucose manufactured by Wako Pure Chemical Industries was used.
[Synthesis of copolymer 1]
(Synthesis of acetyl xylose methacrylate)
20 g of xylose was added to a mixed solution of 250 g of acetic anhydride and 320 g of acetic acid, and the mixture was stirred at 30° C. for 2 hours. Approximately 5 times the amount of cold water as the solution was slowly added while stirring, stirred for 2 hours, and then left to stand overnight. 10 g of precipitated crystals were added to a solution of 1.2 g of ethylenediamine and 10.4 g of acetic acid added to 400 mL of THF and heated to 0° C. and stirred for 4 hours. This was poured into 1 L of cold water and extracted twice with dichloromethane. 20 g of this extract, 300 mL of dichloromethane, and 4.8 g of triethylamine were placed in a flask and cooled to -30°C. 2.8 g of methacryloyl chloride was added and stirred for 2 hours. This was poured into 300 mL of cold water, extracted twice with dichloromethane, and the solvent was concentrated to obtain 16.1 g of acetyl xylose methacrylate. The structure of the obtained acetyl xylose methacrylate is as follows.

(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate-isostearyl acrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 5 g of styrene, 35 g of acetyl xylose methacrylate, 5 g of glycidyl methacrylate, 5 g of isostearyl acrylate, and 0.15 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device. The mixture was added dropwise over 3 hours while keeping the inside of the flask at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain Copolymer 1. The number average molecular weight of the obtained copolymer 1 was 54,000, and the weight average molecular weight was 112,700.
The structure of the obtained copolymer 1 is as follows.

(In the formula, l is 51, m is 24, n is 18, and p is 8.)

[Synthesis of copolymer 2]
(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate-decyl methacrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 5 g of styrene, 35 g of acetyl xylose methacrylate, 5 g of glycidyl methacrylate, 5 g of decyl methacrylate, and 0.15 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device, and the flask was placed in a dropping device. The mixture was added dropwise over a period of 3 hours while maintaining the inside at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 2. The number average molecular weight of the obtained copolymer 2 was 52,000, and the weight average molecular weight was 104,100.
The structure of the obtained copolymer 2 is as follows.

(In the formula, l is 49, m is 23, n is 17, and p is 11.)

[Synthesis of copolymer 3]
(Synthesis of acetyl xylotriose methacrylate-styrene-glycidyl methacrylate-docosyl acrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 5 g of styrene, 35 g of acetyl xylotriose methacrylate, 5 g of glycidyl methacrylate, 5 g of docosyl acrylate, and 0.15 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device. The mixture was added dropwise over 3 hours while keeping the inside of the flask at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 3. The number average molecular weight of the obtained copolymer 3 was 48,000, and the weight average molecular weight was 97,200.
The structure of the obtained copolymer 3 is as follows.

(In the formula, l is 32, m is 34, n is 25, and p is 9.)

[Synthesis of copolymer 4]
(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate-poly(ethylene glycol) methacrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 5 g of styrene, 35 g of acetyl xylose methacrylate, 5 g of glycidyl methacrylate, 5 g of polyethylene glycol monomethacrylate, and 0.5 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device. The mixture was added dropwise over 3 hours while keeping the inside of the flask at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 4. The number average molecular weight of the obtained copolymer 4 was 31,000, and the weight average molecular weight was 58,200.
The structure of the obtained copolymer 4 is as follows.

(In the formula, l is 52, m is 25, n is 18, and p is 5.)

[Synthesis of copolymer 5]
(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate-2-ethylhexyl methacrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 5 g of styrene, 35 g of acetyl xylose methacrylate, 5 g of glycidyl methacrylate, 5 g of 2-ethylhexyl methacrylate, and 0.3 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device. The mixture was added dropwise over 3 hours while keeping the inside of the flask at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 5. The number average molecular weight of the obtained copolymer 5 was 48,000, and the weight average molecular weight was 108,100.
The structure of the obtained copolymer 5 is as follows.

(In the formula, l is 48, m is 23, n is 17, and p is 12.)

[Synthesis of copolymer 6]
(Synthesis of acetyl glucose methacrylate)
Synthesis was carried out in the same manner as in the synthesis of acetyl xylose methacrylate of Copolymer 1, except that 20 g of xylose was changed to 24 g of D-(+)-glucose, and 20.1 g of acetyl glucose methacrylate was obtained. The structure of acetyl glucose methacrylate is as follows.

(Synthesis of acetyl glucose methacrylate-styrene-dibutylene glycol dimethacrylate random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 17.5 g of styrene, 20 g of acetyl glucose methacrylate, 12.5 g of dibutylene glycol dimethacrylate, and 0.5 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device. The mixture was added dropwise over 3 hours while keeping the inside of the flask at 75°C. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 6. The number average molecular weight of the obtained copolymer 6 was 49,000, and the weight average molecular weight was 99,400.
The structure of the obtained copolymer 6 is as follows.

(In the formula, l is 22, m is 63, n is 16, and q is 16.)

[Synthesis of copolymer 7]
(Synthesis of acetyl xylose methacrylate-styrene random copolymer)
25 g of methyl ethyl ketone was added as a solvent to a glass flask equipped with a stirrer, a condenser, and a thermometer, and the temperature was raised to 75° C. while stirring in a nitrogen stream. Next, a dropping solution prepared by dissolving 25 g of styrene, 25 g of acetyl xylose methacrylate, and 0.15 g of dimethyl 2,2'-azobisisobutyrate as a polymerization initiator in 25 g of methyl ethyl ketone was set in the dropping device, and the mixture was heated for 3 hours while keeping the inside of the flask at 75°C. It dripped over time. After the dropwise addition was completed, the mixture was stirred at 75°C for 6 hours. After the reaction was completed, the solvent was distilled off under reduced pressure to obtain copolymer 7. The number average molecular weight of the obtained copolymer 7 was 47,000, and the weight average molecular weight was 91,800.
The structure of the obtained copolymer 7 is as follows.

(In the formula, l is 23 and m is 77.)

[Analysis of copolymer]
(Ratio of unit (l): unit (m): unit (n))
The ratio (mass ratio) of units (l) and units (m) to units (n) of the copolymer was determined and calculated by 1H-NMR. Specifically, 10 mg of polymer was weighed and dissolved in 1 mL of deuterated chloroform to prepare a solution for NMR, and the obtained solution was transferred to an NMR sample tube (Kanto Kagaku Co., Ltd.), and FT-NMR (JNM-ECZ600R: JEOL Co., Ltd.) 1H-NMR measurement was carried out. Note that tetramethylsilane (TMS) was used as an internal standard substance during ¹ H-NMR measurement.

[Measurement of film density]
An X-ray reflectivity measurement method (hereinafter simply referred to as "XRR") was used to measure the thickness of the thin film.
This method allows X-rays to be incident on a material surface within 1 degree or less, and by examining the dependence of X-ray reflectance on the incident angle, film structure parameters such as film thickness, density, and roughness of surfaces and interfaces can be determined. It is something to seek.
In the actual analysis, the difference between the profile (calculated data) simulated using film thickness, density, interface roughness, etc. as parameters based on the film structure model and the profile obtained by measurement (measured data) is minimized. Each parameter is optimized by the least squares method using software and the value of the membrane structure parameter is determined.
References: Non-patent literature, “Thin Film X-ray Measurement Basic Course 5th X-ray Reflectance Measurement”, Miho Yasaka: Rigaku Journal vol. 40, no. 2, (2009) 1-9

Actual film thickness measurement was performed using the following procedure.
(1) Preparation of sample 20 mg of the copolymer was dissolved in 1 mL of PGMEA and spin-coated onto a 2-inch silicon wafer to a thickness of 50 nm. After coating, a measurement sample was prepared by baking at 210° C. for 2 minutes on a hot plate.
(2) Film Thickness Measurement A Bruker D8 DISCOVER device was used for XRR measurement. In order to obtain stable measurement values, the entire apparatus was installed in a constant temperature room at 22.5°C.
Using CuKa radiation as a radiation source, the dependence of the specular reflection intensity on the angle of incidence was measured. The output of the device is 50 kV and 30 mA, and the scanning angle resolution is 0.0002 degrees. Further, the measurement range of specular reflection intensity was set to a detection angle of 0.6 degrees (incident angle to the sample was 0.3 degrees).
A converged solution for the measured profile was obtained using nonlinear least squares fitting using thickness and density as parameters.

[Preparation of solution sample]
Polymer solution samples of each example and comparative example were obtained by adjusting with PGMEA so that each polymer contained 3 wt% and p-toluenesulfonic acid as a polymerization catalyst 0.3 wt%.

[Evaluation of metal introduction rate]
The resulting polymer solution sample was spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 300 nm, it was baked on a hot plate at 230° C. for 5 minutes to form a polymer film sample.

The polymer film sample formed in this way was placed in ALD (atomic layer deposition apparatus: SUNALE R-100B manufactured by PICUSAN), and TMA (trimethylaluminum, Al(CH3)3) gas was introduced for 300 seconds at 95°C. After that, water vapor was introduced for 150 seconds. By repeating this operation three times, Al ₂ O ₃ was introduced into the copolymer film-formed sample.

After introducing Al ₂ O ₃ , the copolymer film sample was subjected to XPS analysis (X-ray photoelectron spectroscopy) using an XPS device (Nexsa XPS System manufactured by Thermo Fisher Scientific) to obtain the Al element concentration profile in the film thickness direction. .

The film thickness of the polymer sample after introduction of Al ₂ O ₃ can be measured by scratching the sample surface with tweezers to expose the silicon substrate surface to form a step. It was determined by measuring with a model number: ET-4000).

The maximum metal content is preferably 15% or more, more preferably 20% or more, and particularly preferably 25% or more.

[Preparation of sample for lower layer film etching selectivity measurement]
The obtained polymer solution sample was spin-coated onto a 2-inch silicon wafer substrate with a silicon oxide film (film thickness: 2 um). After coating to a film thickness of 300 nm, it was baked on a hot plate at 230° C. for 1 minute to form a lower layer film sample.

It was masked in a line-and-space (line width 100 nm, space width 100 nm) shape using an ArF excimer laser exposure machine, and exposure was performed using a commercially available ArF resist. Thereafter, the film was baked on a hot plate at 105° C. for 1 minute, and then immersed in a developer to form a line-and-space pattern.

Next, this pattern sample is subjected to oxygen plasma treatment (100 sccm, 4 Pa, 100 W, 60 seconds) on the substrate using an ICP plasma etching device (manufactured by Tokyo Electron), thereby removing the photoresist and forming lines and lines on the underlying film. A space pattern was formed. Thereafter, metal was introduced into the lower film sample in the same manner as in the evaluation of the metal introduction rate of the copolymer. Using this pattern as a mask, plasma treatment (100 sccm, 0.4 Pa, 200 W, 120 seconds) was performed using an ICP plasma etching device (manufactured by Tokyo Electron) using hexafluoroethane (C ₂ F ₆ ) and Ar gas to remove silicon. The oxide film was dry etched.

[Evaluation of etching selectivity]
The patterned cross section of the substrate before and after plasma treatment using hexafluoroethane (C ₂ F ₆ ) and Ar gas was examined using a scanning electron microscope (SEM) JSM7800F (manufactured by JEOL Ltd.) at an accelerating voltage of 1.5 kV. Observation was made at an emission current of 37.0 μA and a magnification of 100,000 times, and the thickness of the copolymer film into which the metal was introduced and the depth of processing into the silicon oxide film were measured. Etching selection ratio is
Machining depth into silicon oxide film/(copolymer film thickness before treatment - copolymer film thickness after treatment)
Calculated by. The etching selectivity ratio is preferably large, specifically preferably larger than 2.5, more preferably 3 or more, particularly preferably 5 or more. Table 1 shows the results of evaluation based on the following criteria under the above circumstances.
○: Etching selection ratio is 2 or more X: Etching selection ratio is less than 2

As shown in Table 1, with the composition for forming a lower layer film of each Example, a lower layer film with a high residual rate of the lower layer film could be formed in the atmosphere and at a relatively low temperature. Note that in all Examples, the metal introduction rate was high and the etching processability was good.

On the other hand, in Comparative Examples 1 and 2, the metal introduction rate was extremely small and the etching processability was not good. Regarding Comparative Example 3, the lower layer film residual rate was low, the lower layer film residual rate was further low, and the etching processability was also poor.

10 Substrate 20 Lower layer film

Claims (9)

An underlayer film forming composition used for pattern formation, comprising a copolymer and an organic solvent,
The copolymer is
(a) a unit derived from a sugar derivative;
(b) a unit derived from a compound having an antireflection function;
(c) a unit derived from a compound capable of cross-coupling the copolymer;
(d) a unit having a functional group that promotes gas permeation to the underlying film;
The unit derived from the sugar derivative (a) is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative,
The unit (b) derived from a compound having an antireflection function is a unit derived from an aromatic ring-containing compound,
(d) The unit having a functional group that promotes gas permeation to the lower film is a unit derived from an ester of a C10 or higher aliphatic alcohol or a C10 or higher alkoxy polyalkylene glycol and (meth)acrylic acid,
The composition for forming a lower layer film is for introducing a metal. Claim 1, wherein the (b) unit derived from a compound having an antireflection function is at least one type selected from the group consisting of a unit derived from a benzene ring-containing compound and a unit derived from a naphthalene ring-containing compound. The composition for forming a lower layer film as described above. Claim 1 or 2 , wherein the (a) unit derived from a sugar derivative is at least one selected from the group consisting of a unit derived from a cellulose derivative, a unit derived from a hemicellulose derivative, and a unit derived from a xylooligosaccharide derivative. A composition for forming a lower layer film as described in . A pattern forming method comprising the step of forming a lower layer film using the composition for forming a lower layer film according to any one of claims 1 to 3 . 5. The pattern forming method according to claim 4 , including the step of introducing metal into the lower layer film. (a) a unit derived from a sugar derivative;
(b) a unit derived from a compound having an antireflection function;
(c ) a unit derived from a compound capable of cross-coupling the copolymer ;
(d) a unit having a functional group that promotes gas permeation to the underlying film;
The unit derived from the sugar derivative (a) is at least one type selected from a unit derived from a pentose derivative and a unit derived from a hexose derivative,
The unit (b) derived from a compound having an antireflection function is a unit derived from an aromatic ring-containing compound,
(d) The unit having a functional group that promotes gas permeation to the lower film is a unit derived from an ester of a C10 or higher aliphatic alcohol or a C10 or higher alkoxy polyalkylene glycol and (meth)acrylic acid.
copolymer. 7. The copolymer according to claim 6 , wherein the unit derived from the compound having an antireflection function (b) is at least one type selected from the group consisting of units derived from benzene ring-containing compounds. Claim 6 or 7 , wherein the (a) unit derived from a sugar derivative is at least one type selected from the group consisting of a unit derived from a cellulose derivative, a unit derived from a hemicellulose derivative, and a unit derived from a xylooligosaccharide derivative. Copolymers described in. (a) A sugar derivative having a polymerizable unsaturated saturated group, (b) A polymerizable monomer having an antireflection function, (c) A polymerizable monomer having a cross-coupling group, and (d) To the lower layer film. A method for producing a copolymer comprising the step of polymerizing a polymerizable monomer having a functional group that promotes gas permeation of
The sugar derivative (a) having a polymerizable unsaturated group is at least one selected from a pentose derivative having a polymerizable unsaturated group and a hexose derivative having a polymerizable unsaturated group,
The polymerizable monomer having an antireflection function (b) is a polymerizable monomer derived from an aromatic ring-containing compound,
(d) The polymerizable monomer having a functional group that promotes gas permeation to the lower membrane is derived from an ester of a C10 or higher aliphatic alcohol or a C10 or higher alkoxy polyalkylene glycol and (meth)acrylic acid. A method in which the polymerizable monomer is a polymerizable monomer .