JP7839616B2 - Method for forming a resist underlayer film and method for forming a pattern - Google Patents

Description

This invention relates to a method for forming a resist underlayer film and a method for forming a pattern.

In recent years, with the increasing integration and speed of semiconductor devices, there has been a growing demand for miniaturization of pattern rules. In lithography, which currently uses light exposure as a general-purpose technology, various technological developments are being undertaken to achieve finer and more precise pattern processing using the light source employed.

For lithography light sources used in resist pattern formation, light exposure using mercury lamps with g-line (436 nm) or i-line (365 nm) wavelengths is widely used in areas with low integration density. On the other hand, in areas with high integration density and requiring miniaturization, lithography using shorter wavelengths such as KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) has also been put into practical use. Furthermore, in the cutting-edge generation requiring even greater miniaturization, lithography using extreme ultraviolet light (EUV, 13.5 nm) is also approaching practical application.

As resist patterns become finer, the ratio of pattern height to pattern width (aspect ratio) increases in the single-layer resist method, a typical resist pattern formation method. It is well known that this can cause the pattern to collapse during development due to the surface tension of the developer. Therefore, to form high-aspect-ratio patterns on stepped substrates, multilayer resist methods, which involve layering films with different dry-etching properties, are known to be superior. This has led to the development of two-layer resist methods (see, for example, Patent Document 1), which combine a photoresist layer made of a silicon-containing photosensitive polymer with a lower layer made of an organic polymer whose main constituent elements are carbon, hydrogen, and oxygen, such as a novolac polymer. Three-layer resist methods (see, for example, Patent Document 2), which combine a photoresist layer made of an organic photosensitive polymer used in the single-layer resist method with an intermediate layer made of a silicon-based polymer or silicon-based CVD film and a lower layer made of an organic polymer.

In this three-layer resist method, first, a fluorocarbon-based dry etching gas is used to transfer the pattern of the photoresist layer to a silicon-containing intermediate layer. Then, using this pattern as a mask, the pattern is transferred by dry etching to an organic underlayer film mainly composed of carbon and hydrogen using an oxygen-containing gas. Finally, this underlayer film is used as a mask to form a pattern on the substrate by dry etching. However, in semiconductor device manufacturing processes for the 20nm generation and beyond, when this organic underlayer film pattern is used as a hard mask to transfer the pattern to the substrate by dry etching, phenomena such as warping and bending of the underlayer film pattern have been observed.

Generally, amorphous carbon (CVD-C) films are used as carbon hard masks formed directly on the substrate being processed, using methane, ethane, acetylene, etc., as raw materials via the CVD method. While it is known that CVD-C films can drastically reduce the number of hydrogen atoms in the film, making them highly effective against pattern distortion and curvature, it is also known that, due to the characteristics of the CVD process, it is difficult to completely fill in any steps or unevenness in the underlying substrate. Therefore, when a substrate with steps is patterned with a CVD-C film and then patterned with photoresist, the steps in the substrate cause unevenness in the photoresist coating, resulting in an uneven photoresist film thickness and consequently, a deterioration in the focus margin and pattern shape during lithography.

On the other hand, when the underlying carbon hard mask film formed directly on the substrate to be processed is created by spin-coating, it is known to have the advantage of being able to flatten and fill in the steps of the stepped substrate. Planarizing the substrate with this underlying film material suppresses variations in the film thickness of the silicon-containing intermediate layer and photoresist deposited on top, expanding the lithography focus margin and enabling the formation of a normal pattern.

Therefore, there is a need for a base layer material and a method for forming a base layer that can be formed by a spin-coating method, which allows for the formation of a film with high etching resistance and high flatness on the substrate during dry etching of the substrate.

Generally, materials with a high carbon content are used for the resist underlayer. Using such a high-carbon-content material for the resist underlayer improves etching resistance during substrate processing, resulting in more accurate pattern transfer. Thermosetting phenol novolac resins are well-known examples of such resist underlayers (see, for example, Patent Document 1). Furthermore, resist underlayers formed using resist underlayer formation compositions containing acenaphthylene-based polymers are known to exhibit excellent properties (see, for example, Patent Document 2).

Japanese Patent Publication No. 2000-143937 Japanese Patent Publication No. 2001-40293

With the further miniaturization of etching patterns, problems with pattern transfer due to insufficient etching resistance of the resist underlayer film have become a concern, and further improvements in etching resistance are required. In light of the standards required in recent years, the underlayer films obtained by the technologies described in Patent Documents 1 and 2 still have room for improvement in terms of etching resistance (hereinafter simply referred to as "etching resistance") when using fluorocarbon-based gases.

This invention has been made in view of the above circumstances. That is, the object of this invention is to provide a method for forming a resist underlayer film and a method for forming a pattern that can form a resist underlayer film with excellent etching resistance.

In view of the above circumstances, the inventors conducted diligent research and discovered that the above problems could be solved by performing a specific preheat treatment followed by a subsequent heat treatment, thus completing the present invention.

In other words, the present invention encompasses the following embodiments.
[1]
A step of coating a substrate with a composition containing a resist underlayer film forming material selected from the group consisting of aromatic compounds or resins thereof,
A preheat treatment step in which the applied composition is heated to a temperature of 50°C or higher and 300°C or lower,
After the aforementioned preheat treatment step, a heat treatment step is performed in which the material is heated at a temperature of 400°C or higher and less than 800°C in an inert gas atmosphere with an oxygen concentration of less than 5%.
A method for forming a resist underlayer film, including the method described above.
[2]
The method for forming a resist underlayer film according to [1], wherein the composition is heated in an inert gas atmosphere with an oxygen concentration of less than 5% during the preheat treatment step.
[3]
The method for forming a resist underlayer film according to [1] or [2], wherein the aromatic compound is a compound represented by the following formula (1A), and/or the resin is a resin having a structure represented by the following formula (2A).
(In formula (1A), X is an oxygen atom, a sulfur atom, a single bond, or no crosslinking; R ^a is a 2n-valent group or single bond having 1 to 40 carbon atoms; R ^b is independently an alkyl group having 1 to 40 carbon atoms which may be substituted, an aryl group having 6 to 40 carbon atoms which may be substituted, an alkenyl group having 2 to 40 carbon atoms which may be substituted, an alkynyl group having 2 to 40 carbon atoms which may be substituted, an alkoxy group having 1 to 40 carbon atoms which may be substituted, a halogen atom, a thiol group, or a hydroxyl group; m is independently an integer from 0 to 9; n is an integer from 1 to 4; and p is independently an integer from 0 to 2. Here, at least one of R ^b is a group containing one selected from a hydroxyl group and a thiol group, and not all m are 0 at the same time.)
(In formula (2A), X, ^Ra , ^Rb , n, and p are the same as those described in formula (1A), ^Rc is a single bond or an alkylene group having 1 to 40 carbon atoms, and ^m² is an integer from 0 to 8, independently of each other. Here, at least one of ^Rb is a group containing one or more selected from a hydroxyl group and a thiol group, and not all ^m² are 0 at the same time.)
[4]
A method for forming a resist underlayer film according to [1] or [2], wherein the resin is a polycyclic polyphenol resin having repeating units derived from an aromatic hydroxy compound represented by formula (1B), wherein the repeating units are linked to each other by direct bonding of aromatic rings.
(In formula (1B), A represents a benzene ring or a fused ring. Furthermore, each ^R0 is independently an optionally substituted alkyl group having 1 to 40 carbon atoms, an optionally substituted aryl group having 6 to 40 carbon atoms, an optionally substituted alkenyl group having 2 to 40 carbon atoms, an optionally substituted alkynyl group having 2 to 40 carbon atoms, an optionally substituted alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, where at least one of ^R0 is a hydroxyl group and m is an integer from 0 to 9.)
[5]
The method for forming a resist underlayer film according to [3], wherein the compound represented by formula (1A) is the compound represented by the following formula (1).
(In formula (1), X, m, n, and p are the same as those described in formula (1A), ^R1 is the same as ^Ra in formula (1A), and ^R2 is independently one of the following: an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, where at least one of ^R2 is a hydroxyl group or a thiol group, and not all m are 0 at the same time.)
[6]
The method for forming a resist underlayer film according to [5], wherein the compound represented by formula (1) is the compound represented by the following formula (1-1).
(In formula (1-1), Z is an oxygen atom or a sulfur atom, and ^R1 , ^R2 , m, p, and n are the same as those described in formula (1) above. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m are 0 at the same time.)
[7]
The method for forming a resist underlayer film according to [6], wherein the compound represented by formula (1-1) is the compound represented by the following formula (1-2).
(In formula (1-2), ^R1 , ^R2 , m, p, and n are the same as those described in formula (1) above. Here, at least one of ^R2 is a hydroxyl group or a thiol group, and not all m are 0 at the same time.)
[8]
The method for forming a resist underlayer film according to [7], wherein the compound represented by formula (1-2) is the compound represented by formula (1-3) below.
(In formulas (1-3), ^R1 , p, and n are the same as those described in formula (1) above, ^R4 is independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkynyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, or a thiol group, ^m4 is independently an integer from 0 to 8, and q is independently an integer from 0 to 8. Here, not all q can be 0 at the same time.)
[9]
The method for forming a resist underlayer film according to [8], wherein the compound represented by formula (1-3) is the compound represented by formula (1-4) below.
(In equation (1-4), ^R1 , p, and n are equivalent to those explained in equation (1) above, ^R4 is equivalent to those explained in equation (1-3) above, and ^m4 ' is an integer from 0 to 7, each independently.)
[10]
The method for forming a resist underlayer film according to [9], wherein the compound represented by formula (1-4) is the compound represented by formula (1-5) below.
(In the above equations (1-5), ^R1 is equivalent to what was explained in equation (1), ^R4 is equivalent to what was explained in equation (1-3), and ^m4 '' is an integer between 0 and 5, independently of each other.)
[11]
The method for forming a resist underlayer film according to [3], wherein the compound represented by formula (1A) is the compound represented by the following formula (3).
(In formula (3), R ¹ is synonymous with ^Ra in formula (1A), n and p are synonymous with those described in formula (1A), R ⁵ and R ⁶ are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, m ⁵ is each independently an integer from 0 to 8, and m ⁶ is each independently an integer from 0 to 9. Here, at least one selected from R ⁵ and R ⁶ is selected from a hydroxyl group and a thiol group, and not all m ⁵ and m ⁶ are 0 at the same time.)
[12]
The method for forming a resist underlayer film according to [11], wherein the compound represented by formula (3) is the compound represented by the following formula (3-1).
(In formula (3-1), ^R1 , ^R5 , ^R6 , and n are the same as those described in formula (3) above, m5 ^' is an independent integer between 0 and 4, and m6 ^' is an independent integer between 0 and 5. Here, at least one selected from ^R5 and ^R6 is one selected from a hydroxyl group and a thiol group, and not all m5 ^' and ^m6' are 0 at the same time.)
[13]
The method for forming a resist underlayer film according to [12], wherein the compound represented by formula (3-1) is the compound represented by the following formula (3-2).
(In formula (3-2), ^R1 is the same as that described in formula (3) above, ^R7 and ^R8 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkynyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, and ^m7 and ^m8 are each independently an integer from 0 to 7.)
[14]
The method for forming a resist underlayer film according to [3], wherein the resin having the structure represented by formula (2A) is a resin having the structure represented by the following formula (2).
(In formula (2), X, ^R1 , ^R2 , n, and p are the same as those described in formula (1), ^R3 is the same as ^Rc in formula (2A), and ^m2 is the same as those described in formula (2A). Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all ^m2 are 0 at the same time.)
[15]
The method for forming a resist underlayer film according to [14], wherein the resin having the structure represented by formula (2) is a resin having the structure represented by the following formula (2-1).
(In formula (2-1), Z is the same as that described in formula (1-1), ^{and R1} , ^R2 , ^R3 , ^m2 , p, and n are the same as those described in formula (2), where at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all ^m2 are 0 at the same time.)
[16]
A method for forming a resist underlayer film according to [14] or [15], wherein the resin has a structure represented by formula (2) or (2-1), and ^R3 is a single bond, and the aromatic rings are directly linked by ^R3 .
[17]
The method for forming a resist underlayer film according to [3], wherein the resin having the structure represented by formula (2A) is a resin having the structure represented by the following formula (4).
(In formula (4), ^R1 , p, and n are the same as those described in formula (2A) above, ^R5 and ^R6 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, ^m5 is each independently an integer from 0 to 8, and ^m6 is each independently an integer from 0 to 9. Here, at least one selected from ^R5 and ^R6 is selected from a hydroxyl group and a thiol group, and not all ^m5 and ^m6 are 0 at the same time. ^R3 is the same as ^Rc in formula (2A) above.)
[18]
A method for forming a resist underlayer film according to [17], wherein the resin having the structure shown in formula (4) is a single bond, and the aromatic rings are directly linked by ^{R3 .}
[19]
A method for forming a resist underlayer film according to any one of [3], [5] to [18], wherein ^RA or ^R1 is a group represented by ^RA - ^RB , where ^RA is a methine group and ^RB is an aryl group having 6 to 30 carbon atoms, which may have substituents.
[20]
The method for forming a resist underlayer film according to [4], wherein A in formula (1B) is a condensed ring.
[21]
A method for forming a resist underlayer film according to any one of [1] to [20], wherein the resin further comprises a modified portion derived from a crosslinking reactive compound.
[22]
The method for forming a resist underlayer film according to [21], wherein the crosslinking reactive compound is an aldehyde or a ketone.
[23]
A method for forming a resist underlayer film according to any one of [1] to [22], wherein the weight-average molecular weight of the resin is 1,000 to 1,000,000.
[24]
A step of forming the resist underlayer film on the substrate by the resist underlayer film formation method described in any of [1] to [23],
A step of forming a silicon-containing intermediate layer by coating a silicon atom-containing intermediate layer-forming composition onto the resist underlayer film and baking it,
The steps include forming a resist film on the silicon-containing intermediate layer,
The steps include at least exposing and developing the resist film to form a resist pattern,
Using the resist pattern as a mask, a step is performed to dry etch the silicon-containing intermediate layer using a gas containing fluorocarbons,
A pattern formation method, including the following.

According to the present invention, it is possible to provide a resist underlayer film, etc., that has excellent performance in terms of properties such as etching resistance.

The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be appropriately modified and implemented within the scope of its gist.

<Method for forming a resist underlayer film>
The method for forming a resist underlayer film according to this embodiment includes the steps of: applying a composition containing a resist underlayer film forming material selected from the group consisting of aromatic compounds or resins thereof onto a substrate; a preheat treatment step of heating the applied composition at 50°C to 300°C; and a heat treatment step of heating at a temperature of 400°C to 800°C in an inert gas atmosphere with an oxygen concentration of less than 5% after the preheat treatment step. Because of this configuration, the resist underlayer film formation method according to this embodiment can provide a resist underlayer film with excellent performance in terms of etching resistance and other properties. If the etching resistance of the resist underlayer film is insufficient, for example, when etching a substrate such as an oxide film or nitride film, transfer dimensional fluctuations will occur due to insufficient mask resistance of the resist underlayer film. That is, if a resist underlayer film with excellent etching resistance can be formed, a pattern with a good shape can be formed. Therefore, the resist underlayer film formation method according to this embodiment can be suitably used for pattern formation using a multilayer resist process for semiconductor devices where further miniaturization of patterns is progressing.
The resist underlayer film formation material in this embodiment will be described in more detail below.

[Material for forming a resist underlayer film]
The material for forming the resist underlayer in this embodiment is selected from the group consisting of aromatic compounds or resins thereof, that is, it has at least one aromatic ring unit.

(aromatic compound)
The aromatic compounds in this embodiment are not particularly limited as long as they have an aromatic ring and can be applied to materials for forming a resist underlayer film. The aromatic compounds in this embodiment will be described in detail below.

(The compound represented by formula (1A))
In this embodiment, the aromatic compound is preferably a compound represented by the following formula (1A).
(In formula (1A), X is an oxygen atom, a sulfur atom, a single bond, or no crosslinking; R ^a is a 2n-valent group or single bond having 1 to 40 carbon atoms; R ^b is independently an alkyl group having 1 to 40 carbon atoms which may be substituted, an aryl group having 6 to 40 carbon atoms which may be substituted, an alkenyl group having 2 to 40 carbon atoms which may be substituted, an alkynyl group having 2 to 40 carbon atoms which may be substituted, an alkoxy group having 1 to 40 carbon atoms which may be substituted, a halogen atom, a thiol group, or a hydroxyl group; m is independently an integer from 0 to 9; n is an integer from 1 to 4; and p is independently an integer from 0 to 2. Here, at least one of R ^b is a group containing one selected from a hydroxyl group and a thiol group, and not all m are 0 at the same time.)

In this specification, unless otherwise defined, "substitution" means that one or more hydrogen atoms in a functional group are replaced by a substituent. Substituents are not particularly limited, but examples include halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, thiol groups, heterocyclic groups, C1-C30 alkyl groups, C6-C20 aryl groups, C1-C30 alkoxyl groups, C2-C30 alkenyl groups, C2-C30 alkynyl groups, C1-C30 acyl groups, and C0-C30 amino groups.
Furthermore, unless otherwise defined, "alkyl group" includes linear aliphatic hydrocarbon groups, branched aliphatic hydrocarbon groups, and cyclic aliphatic hydrocarbon groups.

In formula (1A), X represents an oxygen atom, a sulfur atom, a single bond, or no bridging. In this embodiment, X is preferably an oxygen atom or no bridging.
R ^a is a 2n-valent group or single bond having 1 to 40 carbon atoms. A 2n-valent group having 1 to 40 carbon atoms refers to, for example, an alkylene group having 1 to 40 carbon atoms when n=1, an alkanetetrayl group having 1 to 40 carbon atoms when n=2, an alkanehexyl group having 2 to 40 carbon atoms when n=3, and an alkaneoctile group having 3 to 40 carbon atoms when n=4. Examples of such 2n-valent groups include groups formed by bonding a 2n+1 valent hydrocarbon group with a linear hydrocarbon group, a branched hydrocarbon group, or an alicyclic hydrocarbon group. Here, alicyclic hydrocarbon groups also include bridged alicyclic hydrocarbon groups.
Examples of 2n+1 valent hydrocarbon groups include, but are not limited to, trivalent methine groups and ethyne groups.
Furthermore, the 2n-valent hydrocarbon group may have a double bond, a heteroatom, and/or an aryl group having 6 to 39 carbon atoms. Note that ^R1 may include a group derived from a compound having a fluorene skeleton, such as fluorene or benzofluorene.
Furthermore, the 2n-valent group may include a halogen group, a nitro group, an amino group, a hydroxyl group, an alkoxy group, a thiol group, or an aromatic group having 6 to 40 carbon atoms. In addition, the 2n-valent group may include an ether bond, a ketone bond, an ester bond, or a double bond.
Substituents that may be included in a 2n-valent group are not particularly limited as linear hydrocarbon groups or branched hydrocarbon groups, but examples include unsubstituted methyl groups, ethyl groups, n-propyl groups, i-propyl groups, n-butyl groups, i-butyl groups, t-butyl groups, n-pentyl groups, n-hexyl groups, n-dodecyl groups, barrel groups, etc.
Substituents that may be included in a 2n-valent group, and which are alicyclic hydrocarbon groups and aromatic groups having 6 to 39 carbon atoms, are not particularly limited, but for example, unsubstituted phenyl group, naphthalene group, biphenyl group, anthrasyl group, pyrenyl group, cyclohexyl group, cyclododecyl group, dicyclopentyl group, tricyclodecyl group, adamantyl group, phenylene group, naphthalenediyl group, biphenyldiyl group, anthracenediyl group, pyrenediyl group, cyclohexanediyl group, cyclododecanediyl group, dicyclopentanediyl group, tricyclodecanediyl group, adamantanediyl group, Examples include benzenetriyl group, naphthalenetriyl group, biphenyltriyl group, anthracenatetriyl group, pyrentriyl group, cyclohexanetriyl group, cyclododecanetriyl group, dicyclopentanetriyl group, tricyclodecanetriyl group, adamantanetriyl group, benzenetetrayl group, naphthalenetetrayl group, biphenyltetrayl group, anthracenetetrayl group, pyrenetetrayl group, cyclohexanetetrayl group, cyclododecanetetrayl group, dicyclopentanetetrayl group, tricyclodecanetetrayl group, adamantanetetrayl group, etc.
Each of ^Rb is independently an alkyl group having 1 to 40 carbon atoms, which may be substituted; an aryl group having 6 to 40 carbon atoms, which may be substituted; an alkenyl group having 2 to 40 carbon atoms, which may be substituted; an alkoxy group having 1 to 40 carbon atoms, which may be substituted; a halogen atom; a thiol group; or a hydroxyl group. Here, the alkyl group may be linear, branched, or cyclic.
Here, at least one of ^Rb is a group that includes one selected from a hydroxyl group and a thiol group.
Examples of alkyl groups having 1 to 40 carbon atoms include, but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, n-hexyl, n-dodecyl, and barrel groups.
Examples of aryl groups having 6 to 40 carbon atoms include, but are not limited to, phenyl, naphthalene, biphenyl, anthrasyl, pyrenyl, and perylene groups.
Alkenyl groups having 2 to 40 carbon atoms are not limited to the following, but examples include ethynyl, propenyl, butynyl, and pentynyl groups.
Examples of alkynyl groups having 2 to 40 carbon atoms include, but are not limited to, acetylene groups, ethynyl groups, etc.
Examples of alkoxy groups having 1 to 40 carbon atoms include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, and pentoxy groups.
Examples of halogen atoms include, but are not limited to, fluorine, chlorine, bromine, and iodine.
Each of m is an independent integer between 0 and 9. Here, it is impossible for all m to be 0 at the same time.
n is an integer between 1 and 4, and p is an independent integer between 0 and 2.

In this embodiment, from the viewpoint of ease of manufacture, the compound represented by formula (1A) is preferably the compound represented by the following formula (1).
(In formula (1), X, m, n, and p are the same as those described in formula (1A), ^R1 is the same as ^Ra in formula (1A), and ^R2 is independently one of the following: an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, where at least one of ^R2 is a hydroxyl group or a thiol group, and not all m are 0 at the same time.)

In this embodiment, the compound represented by formula (1) is preferably the compound represented by the following formula (1-1) from the viewpoint of heat resistance.
(In formula (1-1), Z is an oxygen atom or a sulfur atom, and ^R1 , ^R2 , m, p, and n are the same as those described in formula (1) above. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m are 0 at the same time.)

Furthermore, the compound represented by formula (1-1) above is preferably the compound represented by formula (1-2) below from the viewpoint of raw material supply.
(In formula (1-2), ^R1 , ^R2 , m, p, and n are the same as those described in formula (1) above. Here, at least one of ^R2 is a hydroxyl group or a thiol group, and not all m are 0 at the same time.)

Furthermore, the compound represented by formula (1-2) is preferably the compound represented by formula (1-3) below, from the viewpoint of thermosetting properties and solubility.
(In formulas (1-3), ^R1 , p, and n are the same as those described in formula (1) above, ^R4 is independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkynyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, or a thiol group, ^m4 is independently an integer from 0 to 8, and q is independently an integer from 0 to 8. Here, not all q can be 0 at the same time.)

Furthermore, the compound represented by formula (1-3) is preferably the compound represented by formula (1-4) below, from the viewpoint of heat resistance and solubility.
(In equation (1-4), ^R1 , p, and n are equivalent to those explained in equation (1) above, ^R4 is equivalent to those explained in equation (1-3) above, and ^m4 ' is an integer from 0 to 7, each independently.)

Furthermore, the compound represented by formula (1-4) is preferably the compound represented by formula (1-5) below, from the viewpoint of raw material availability and ease of manufacture.
(In the above equations (1-5), ^R1 is equivalent to what was explained in equation (1), ^R4 is equivalent to what was explained in equation (1-3), and ^m4 '' is an integer between 0 and 5, independently of each other.)

Furthermore, the compound represented by formula (1A) is preferably the compound represented by formula (3) below from the viewpoint of improving solubility.
(In formula (3), R ¹ is synonymous with ^Ra in formula (1A), n and p are synonymous with those described in formula (1A), R ⁵ and R ⁶ are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, m ⁵ is each independently an integer from 0 to 8, and m ⁶ is each independently an integer from 0 to 9. Here, at least one selected from R ⁵ and R ⁶ is selected from a hydroxyl group and a thiol group, and not all m ⁵ and m ⁶ are 0 at the same time.)

The compound represented by formula (3) is preferably the compound represented by the following formula (3-1) from the viewpoint of raw material availability.
(In formula (3-1), ^R1 , ^R5 , ^R6 , and n are the same as those described in formula (3) above, m5 ^' is an independent integer between 0 and 4, and m6 ^' is an independent integer between 0 and 5. Here, at least one selected from ^R5 and ^R6 is one selected from a hydroxyl group and a thiol group, and not all m5 ^' and ^m6' are 0 at the same time.)

The compound represented by formula (3-1) is preferably the compound represented by the following formula (3-2) from the viewpoint of raw material availability and ease of manufacture.
(In formula (3-2), ^R1 is the same as that described in formula (3) above, ^R7 and ^R8 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkynyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, and ^m7 and ^m8 are each independently an integer from 0 to 7.)

Specific examples of compounds represented by formula (1) are given below, but this list is not exhaustive.

In the above formula, ^R2 and X are the same as those explained in formula (1) above. m' is an integer from 0 to 7. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m' are 0 at the same time.

In the above formula, ^R² and X are equivalent to those explained in formula (1) above.
m' is an integer between 0 and 7. m'' is an integer between 0 and 5. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and m' and m'' cannot be 0 at the same time.

In the above formula, ^R2 , X, and m' have the same meanings as those explained above. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m' are 0 at the same time.

In the above formula, ^R2 and X are equivalent to those explained in formula (1) above. m' is an integer from 0 to 7. m'' is an integer from 0 to 5. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and m' and m'' cannot be 0 at the same time.

In the above formula, ^R2 and X are the same as those explained in formula (1) above. m' is an integer from 0 to 7. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m' are 0 at the same time.

In the above formula, ^R2 and X are equivalent to those explained in formula (1) above. m' is an integer from 0 to 7. m'' is an integer from 0 to 5. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and m' and m'' cannot be 0 at the same time.

In the above formula, ^R2 and X are the same as those described in formula (1). m' is an integer from 0 to 7. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all m' are 0 at the same time.

In the above formula, ^R2 and X are the same as those described in formula (1). m' is an integer from 0 to 7. m'' is an integer from 0 to 5. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and m' and m'' cannot be 0 at the same time.

The following are specific examples of compounds represented by formula (3) above, but this list is not exhaustive.

In the above compound, R ⁵ and R ⁶ are equivalent to those described in formula (3) above.
^m11 is an integer between 0 and 6, and ^m12 is an integer between 0 and 7.
Here, at least one selected from R ⁵ and R ⁶ is one of the hydroxyl group and thiol group, and not all of m ¹¹ and m ¹² are 0 at the same time.

In the above compound, R ⁵ and R ⁶ are equivalent to those described in formula (3) above.
Each of m ^5' is an independent integer between 0 and 4, and each of m ^6' is an independent integer between 0 and 5.
Here, at least one selected from R ⁵ and R ⁶ is one of a hydroxyl group and a thiol group, and not all of m ^5' and m ^6' are 0 at the same time.

In the above compound, R ⁵ and R ⁶ are equivalent to those described in formula (3) above. m ¹¹ is an integer from 0 to 6, and m ¹² is an integer from 0 to 7.
Here, at least one of ^R11 and ^R12 is selected from a hydroxyl group and a thiol group, and not all of ^m11 and ^m12 are 0 at the same time.

In the above compound, R ⁵ and R ⁶ are equivalent to those described in formula (1) above.
Each of m ^5' is an independent integer between 0 and 4, and each of m ^6' is an independent integer between 0 and 5.
Here, at least one selected from R ⁵ and R ⁶ is one of a hydroxyl group and a thiol group, and not all of m ^5' and m ^6' are 0 at the same time.

(Method for preparing the compound represented by formula (1A))
The compound represented by formula (1A) in this embodiment can be synthesized as appropriate by applying known methods, and the synthesis method is not particularly limited. The compound can be produced, for example, by methods described in International Publication 2013/024779 and International Publication 2015/137486. These documents describe methods such as reacting naphthols, biphenols, etc., with aldehydes, ketones, etc., under acid catalyst.

(resin)
The resin in this embodiment is not particularly limited as long as it is derived from the aromatic compound in this embodiment. The resin in this embodiment will be described in detail below.

(A resin having the structure represented by formula (2A))
In this embodiment, the resin is preferably a resin having a structure represented by the following formula (2A).
(In formula (2A), X, ^Ra , ^Rb , n, and p are the same as those described in formula (1A), ^Rc is a single bond or an alkylene group having 1 to 40 carbon atoms, and ^m² is an integer from 0 to 8, independently of each other. Here, at least one of ^Rb is a group containing one or more selected from a hydroxyl group and a thiol group, and not all ^m² are 0 at the same time.)

The resin having the structure represented by formula (2A) is preferably a resin having the structure represented by the following formula (2) from the viewpoint of ease of manufacture.
(In formula (2), X, ^R1 , ^R2 , n, and p are the same as those described in formula (1), ^R3 is the same as ^Rc in formula (2A), and ^m2 is the same as those described in formula (2A). Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all ^m2 are 0 at the same time.)

The resin having the structure represented by formula (2) is preferably a resin having the structure represented by the following formula (2-1) from the viewpoint of improving heat resistance.

In formula (2-1), Z has the same meaning as explained in formula (1-1), and indicates that it is either an oxygen atom or a sulfur atom.
^R1 , ^R2 , ^R3 , ^m2 , p, and n are equivalent to those described in formula (2) above. Here, at least one of ^R2 is selected from a hydroxyl group and a thiol group, and not all ^m2 are 0 at the same time.

In this embodiment, it is preferable that in the resin having the structure represented by formula (2) or (2-1), ^R3 is a single bond, and that the aromatic rings are directly linked by ^R3 . In this specification, a resin having a structure in which aromatic rings are directly linked is also called a "polycyclic polyphenol resin." That is, it is preferable that the resin having the structure represented by formula (2) or (2-1) is a polycyclic polyphenol resin.

Furthermore, the resin having the structure represented by formula (2A) is preferably having the structure represented by the following formula (4) from the viewpoint of dissolution stability.
(In formula (4), ^R1 , p, and n are the same as those described in formula (2A) above, ^R5 and ^R6 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, ^m5 is each independently an integer from 0 to 8, and ^m6 is each independently an integer from 0 to 9. Here, at least one selected from ^R5 and ^R6 is selected from a hydroxyl group and a thiol group, and not all ^m5 and ^m6 are 0 at the same time. ^R3 is the same as ^Rc in formula (2A) above.)

In this embodiment, it is preferable that in the resin having the structure represented by formula (4), ^R3 is a single bond, and that the aromatic rings are directly linked by ^R3 . That is, it is preferable that the resin having the structure represented by formula (4) is a polycyclic polyphenol resin.

[Method for preparing a resin having the structure represented by formula (2A)]
The resin having the structure represented by formula (2A) used in this embodiment can be synthesized as appropriate by applying known methods, and the synthesis method is not particularly limited. The resin can be produced, for example, by methods described in International Publication No. 2013/024779 and International Publication No. 2015/137486. These documents describe methods for oligomerizing or polymerizing compounds obtained by reacting naphthols, biphenols, etc., with aldehydes or ketones under acid catalyst under crosslinking reactivity with a crosslinking compound.

In this embodiment, RA or R1 in formulas (1A), (2A), (1), (1-1), (1-2), (1-3), (1-4), (1-5), (3), (3-1), (3-2), (2), (2-1), and ( ⁴ ) may be ^a 2n-valent group having 1 to 40 carbon atoms and containing an aryl group, or a group having a fluorene skeleton.
In this embodiment, RA or R1 in formulas (1A), (2A), (1), (1-1), (1-2), (1-3), (1-4), (1-5), (3), (3-1), (3-2), (2 ⁾ , ( ^2-1 ), and (4) is preferably a group represented by ^RA - ^RB , where ^RA is a methine group and ^RB is preferably an aryl group having 6 to 30 carbon atoms, which may have substituents.
The above-mentioned aryl groups having 6 to 30 carbon atoms are not limited to the following, but may include, for example, groups derived from a benzene ring, or groups derived from various known fused rings such as naphthalene, anthracene, naphthacene, pentacene, benzopyrene, chrysene, pyrene, triphenylene, corannulene, coronene, and ovalene.
Furthermore, examples of groups having a fluorene skeleton include 2n-valent groups derived from fluorene, benzofluorene, and dibenzofluorene.

[Polycyclic polyphenol resin having repeating units derived from aromatic hydroxy compounds represented by formula (1B)]
In this embodiment, the resin may be a polycyclic polyphenol resin having repeating units derived from an aromatic hydroxy compound represented by formula (1B), wherein the repeating units are linked to each other by direct bonding of aromatic rings.
(In formula (1B), A represents a benzene ring or a fused ring. Furthermore, each ^R0 is independently an optionally substituted alkyl group having 1 to 40 carbon atoms, an optionally substituted aryl group having 6 to 40 carbon atoms, an optionally substituted alkenyl group having 2 to 40 carbon atoms, an optionally substituted alkynyl group having 2 to 40 carbon atoms, an optionally substituted alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, where at least one of ^R0 is a hydroxyl group and m is an integer from 0 to 9.)

Furthermore, A in formula (1B) is not particularly limited, but may be a benzene ring, or various known condensed rings such as naphthalene, anthracene, naphthacene, pentacene, benzopyrene, chrysene, pyrene, triphenylene, corannulene, coronene, and ovalene. In this embodiment, it is preferable from the viewpoint of heat resistance that A is various condensed rings such as naphthalene, anthracene, naphthacene, pentacene, benzopyrene, chrysene, pyrene, triphenylene, corannulene, coronene, and ovalene. It is also preferable that A is naphthalene or anthracene because the n and k values at the wavelength of 193 nm used in ArF exposure are low, and the pattern transfer performance tends to be excellent.
Furthermore, A above includes, in addition to the aromatic hydrocarbon rings described above, heterocycles such as pyridine, pyrrole, pyridazine, thiophene, imidazole, furan, pyrazole, oxazole, triazole, thiazole, or benzo-fused compounds thereof.

In this embodiment, preferred examples of aromatic hydroxy compounds represented by formula (1B) include aromatic hydroxy compounds represented by the following formulas (1B') and (1B'').
(In equation (1B'), ^R0 , m, and p are equivalent to ^Rb , m, and p in equation (1A), respectively. Also, in equation (1B''), ^R0 is equivalent to ^Rb in equation (1A), ^m0 is an integer from 0 to 4, and not all m0 are ⁰ at the same time.)

Specific examples of aromatic hydroxy compounds represented by formula (1B') are shown below, but this list is not exhaustive.

In equation (B-1), ^n₀ is an integer from 0 to 4; in equation (B-2), ^n₀ is an integer from 0 to 6; and in equations (B-3) to (B-4), ^n₀ is an integer from 0 to 8.

Among the aromatic hydroxy compounds represented by formulas (B-1) to (B-4), those represented by (B-3) to (B-4) are preferred from the viewpoint of improving etching resistance. Furthermore, those represented by (B-2) to (B-3) are preferred from the viewpoint of optical properties. Moreover, those represented by (B-1) to (B-2) and (B-4) are preferred from the viewpoint of flatness, and those represented by (B-4) are more preferred.
From the viewpoint of heat resistance, it is preferable that one carbon atom of any of the aromatic rings having a phenolic hydroxyl group is involved in the direct bonding between the aromatic rings.

Specific examples of aromatic hydroxy compounds represented by the above formula (1B'') are shown below, but this list is not exhaustive.

In addition to the above, from the perspective of further improving etching resistance, aromatic hydroxy compounds represented by B-5 below can also be used as specific examples of formula (1B).
(In equation (B-5), ⁿ¹ is an integer between 0 and 8.)

Furthermore, in this embodiment, the aromatic hydroxy compound represented by formula (1B) above can also be used as the aromatic compound in this embodiment.

The resin in this embodiment may further have a modified portion derived from a crosslinking-reactive compound. That is, the resin in this embodiment having the structure described above may have a modified portion obtained by reaction with a crosslinking-reactive compound. Such a modified resin also exhibits excellent heat resistance and etching resistance, and can be used as a coating agent for semiconductors, a resist material, and a semiconductor underlayer film forming material.

Compounds with crosslinking reactivity include, but are not limited to, aldehydes, ketones, carboxylic acids, carboxylic acid halides, halogen-containing compounds, amino compounds, imino compounds, isocyanate compounds, and unsaturated hydrocarbon group-containing compounds. These can be used individually or in combination as appropriate.

In this embodiment, the crosslinking-reactive compound is preferably an aldehyde or a ketone. In particular, it is preferable to obtain a polycyclic polyphenol resin obtained by polycondensing the resin having the aforementioned structure with an aldehyde or ketone in the presence of a catalyst. For example, a novolac-type polycyclic polyphenol resin can be obtained by further polycondensing the aldehyde or ketone corresponding to the desired structure under atmospheric pressure, or under pressurized pressure if necessary, in the presence of a catalyst.

Examples of the aldehydes mentioned above include, but are not limited to, methylbenzaldehyde, dimethylbenzaldehyde, trimethylbenzaldehyde, ethylbenzaldehyde, propylbenzaldehyde, butylbenzaldehyde, pentabenzaldehyde, butylmethylbenzaldehyde, hydroxybenzaldehyde, dihydroxybenzaldehyde, and fluoromethylbenzaldehyde. These can be used individually or in combination of two or more. Among these, methylbenzaldehyde, dimethylbenzaldehyde, trimethylbenzaldehyde, ethylbenzaldehyde, propylbenzaldehyde, butylbenzaldehyde, pentabenzaldehyde, and butylmethylbenzaldehyde are preferred from the viewpoint of providing high heat resistance.

Examples of the aforementioned ketones include, but are not limited to, acetylmethylbenzene, acetyldimethylbenzene, acetyltrimethylbenzene, acetylethylbenzene, acetylpropylbenzene, acetylbutylbenzene, acetylpentabenzene, acetylbutylmethylbenzene, acetylhydroxybenzene, acetyldihydroxybenzene, and acetylfluoromethylbenzene. These can be used individually or in combination of two or more. Among these, acetylmethylbenzene, acetyldimethylbenzene, acetyltrimethylbenzene, acetylethylbenzene, acetylpropylbenzene, acetylbutylbenzene, acetylpentabenzene, and acetylbutylmethylbenzene are preferred from the viewpoint of providing high heat resistance.

The catalyst used in the above reaction can be appropriately selected from known catalysts and is not particularly limited. Acid catalysts and base catalysts are preferably used.
Inorganic acids and organic acids are widely known as such acid catalysts. Specific examples of the above acid catalysts include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, and hydrofluoric acid; organic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, citric acid, fumaric acid, maleic acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, and naphthalenedisulfonic acid; Lewis acids such as zinc chloride, aluminum chloride, iron chloride, and boron trifluoride; and solid acids such as silicic acid, phosphotungstic acid, silicic acid, molybdic acid, and phosphomolybdic acid, but are not particularly limited to these. Among these, organic acids and solid acids are preferred from a manufacturing standpoint, and hydrochloric acid or sulfuric acid is preferred from a manufacturing standpoint such as ease of availability and handling.
Examples of such base catalysts include pyridine and ethylenediamine as amine-containing catalysts, and metal salts, and especially potassium salts or acetate salts as non-amine basic catalysts. Suitable catalysts, though not limited to these, include potassium acetate, potassium carbonate, potassium hydroxide, sodium acetate, sodium carbonate, sodium hydroxide, and magnesium oxide.
All nonamine base catalysts used in this embodiment are commercially available from, for example, EM Science or Aldrich.
The catalyst can be used individually or in combination of two or more types. The amount of catalyst used can be appropriately set according to the raw materials used, the type of catalyst used, and the reaction conditions, and is not particularly limited, but it is preferably 0.001 to 100 parts by mass per 100 parts by mass of the reaction raw materials.

A reaction solvent may be used in the above reaction. The reaction solvent is not particularly limited as long as it allows the reaction between the aldehydes or ketones used and the resin in this embodiment to proceed, and can be appropriately selected from known solvents. Examples include water, methanol, ethanol, propanol, butanol, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, or mixed solvents thereof. The solvent can be used individually or in combination of two or more. The amount of these solvents used can be appropriately set depending on the type of raw materials and acid catalyst used, as well as the reaction conditions. The amount of solvent used is not particularly limited, but is preferably in the range of 0 to 2000 parts by mass per 100 parts by mass of reaction raw materials. Furthermore, the reaction temperature in the above reaction can be appropriately selected depending on the reactivity of the reaction raw materials. The reaction temperature is not particularly limited, but is usually preferably in the range of 10 to 200°C. The reaction method is not particularly limited and can be selected from known methods as appropriate. Examples include charging the resin, aldehydes or ketones, and acid catalyst all at once, or adding the aldehydes or ketones dropwise in the presence of the acid catalyst. After the polycondensation reaction is complete, the resulting compound can be isolated according to conventional methods and is not particularly limited. For example, the target compound can be obtained by raising the temperature of the reaction vessel to 130-230°C and removing volatile components at approximately 1-50 mmHg, among other general methods, to remove unreacted raw materials and acid catalyst present in the system.

In the resin of this embodiment, the number and ratio of each repeating unit are not particularly limited, but it is preferable to adjust them appropriately considering the application and the molecular weight values described below.
Furthermore, the polycyclic polyphenol resin in this embodiment can be composed of only the aforementioned specific repeating units, such as repeating units (1A) and/or (1B), but it may also include other repeating units as long as it does not impair the performance according to the application. Other repeating units include, for example, repeating units having ether bonds formed by the condensation of phenolic hydroxyl groups, and repeating units having a ketone structure. These other repeating units may also be directly bonded to repeating units (1A) and/or (1B) via aromatic rings.
For example, in this embodiment, the molar ratio [Y/X] of the total amount of repeating units (1A) and/or (1B) (Y) to the total amount of polycyclic polyphenol resin (X) can be 0.05 to 1.00, preferably 0.45 to 1.00.
The mass-average molecular weight of the resin in this embodiment is not particularly limited, but is preferably in the range of 1,000 to 100,000, more preferably 1,000 to 15,000, and even more preferably 3,200 to 12,000.
The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw/Mn) is not particularly limited in range, as the required ratio varies depending on the application. However, for materials with a more homogeneous molecular weight, for example, a preferred range is 3.0 or less, a more preferred range is 1.05 to 3.0, a particularly preferred range is 1.05 to less than 2.0, and an even more preferred range is 1.05 to less than 1.5 from the viewpoint of heat resistance.

The bonding order of the repeating units in the polycyclic polyphenol resin in this embodiment is not particularly limited. For example, the resin may contain two or more repeating units derived from only one aromatic hydroxy compound represented by formula (1A) or formula (1B), or it may contain one or more units each derived from multiple aromatic hydroxy compounds represented by formula (1A) or formula (1B). The bonding order may also be either block copolymerization or random copolymerization.

In this embodiment, the positions where repeating units in the polycyclic polyphenol resin are directly bonded to each other are not particularly limited. When the repeating unit is represented by the general formula (1A) or formula (1B), any one carbon atom that is not bonded to a phenolic hydroxyl group or other substituents is involved in the direct bonding between monomers.
In the polycyclic polyphenol resin of this embodiment, "the repeating units are linked by direct bonding between aromatic rings" means, as an example, that in the polycyclic polyphenol resin, the carbon atoms on the aromatic ring, which are shown as an aryl structure in parentheses in the formula of one repeating unit (1A), and the carbon atoms on the aromatic ring, which are shown as an aryl structure in parentheses in the formula of the other repeating unit (1A), are directly bonded by single bonds, that is, without the intermediary of other atoms such as carbon atoms, oxygen atoms, or sulfur atoms.
Furthermore, this embodiment may include the following aspects.
(1) In one repeating unit (1A), if either ^Ra or ^Rb is an aryl group (including the case where ^Ra is a 2n-valent group having an aryl group), the atom on the aromatic ring of the aryl group and the atom on the aromatic ring of the other repeating unit (1A), which is indicated by the aryl structure in parentheses in the formula, are directly bonded by a single bond.
(2) In one repeating unit (1A) and the other, if either Ra ^a or R ^b is an aryl group (including the case where Ra ^a is a 2n valent group having an aryl group), the atoms on the aromatic rings of the aryl groups represented by Ra ^a and R ^b are directly bonded to each other by single bonds between the one repeating unit (1A) and the other.
In this embodiment, in either embodiment (1) or (2) above, from the viewpoint of heat resistance, it is preferable that one carbon atom of the aromatic ring having a phenolic hydroxyl group is involved in the direct bonding between the aromatic rings.

[Composition]
The composition in this embodiment is not particularly limited as long as it contains the resist underlayer film forming material described above, and may contain various other components. For example, the composition in this embodiment may contain the resist underlayer film forming material described above and a solvent described later, and the composition may further contain various surfactants, various crosslinking agents, various acid generators, various stabilizers, etc.

(solvent)
As the solvent used in the composition of this embodiment, any known solvent can be used as appropriate, as long as it can at least dissolve the resist underlayer film forming material described above.

Specific examples of solvents are not limited to those described in International Publication No. 2013/024779.
Specific examples of solvents used include, but are not limited to, ethyl ether, isopropyl ether, n-butyl ether, hexyl ether, 2-ethylhexyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyldioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-n-hexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol dibutyl ether, propylene glycol monomethyl ether (PGME), dipropylene glycol methyl ether, Ethers such as tripropylene glycol methyl ether, propylene glycol monopropyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol Nonyl alcohol, heptanol-3, n-octanol, 2-ethylhexanol, sec-octanol, nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, cresol and other monoalcohols, diethyl carbohydrate Ponate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene acetate Esters such as glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-pentyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-pentyl lactate, diethyl malonate, dimethyl phthalate, and diethyl phthalate. Ketones such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, ethyl butyl ketone, methylhexyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone, N-methylpyrrolidone, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl Examples include glycol ether acetates such as propylene glycol monoethyl ether acetate (PGMEA), nitrogen compound solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, and N-methylpyrrolidone, aliphatic hydrocarbons such as n-hexane and n-heptane, aromatic hydrocarbons such as toluene and xylene, and halogenated hydrocarbons such as methylene chloride and chloroform.

Among these, ethyl acetate, butyl acetate, methyl isobutyl ketone, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), cyclopentanone, cyclohexanone, methyl hydroxyisobutyrate, and anisole are preferred. These solvents can be used individually or in combination of two or more. This is preferable in terms of ease of use and control of the amount of preparation.

The solvents mentioned above can be used individually or in combination of two or more.

The solvent content is not particularly limited, but from the viewpoint of solubility and film formation, it is preferably 100 to 10,000 parts by mass, more preferably 200 to 5,000 parts by mass, and even more preferably 200 to 1,000 parts by mass, per 100 parts by mass of the resist underlayer film forming material in this embodiment.

In this embodiment, the content of the resist underlayer film forming material is preferably 1 to 100% by mass, more preferably 10 to 100% by mass, even more preferably 50 to 100% by mass, and particularly preferably 100% by mass, from the viewpoint of coatability and quality stability.

When the composition in this embodiment contains a solvent, the content of the resist underlayer film forming material in this embodiment is not particularly limited, but is preferably 1 to 33 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, per 100 parts by mass of the total amount including the solvent.

The composition in this embodiment is applicable to wet processes and exhibits excellent heat resistance and etching resistance. Furthermore, because the composition in this embodiment includes the resist underlayer film forming material, by performing the pre-heat treatment and heat treatment steps described later, film degradation during high-temperature baking is suppressed, and an underlayer film with excellent etching resistance to oxygen plasma etching and the like can be formed. Moreover, the composition in this embodiment tends to have excellent adhesion to the resist layer, resulting in a tendency to obtain excellent resist patterns. Note that the composition in this embodiment may also include already known lithography underlayer film forming materials, etc., to the extent that the desired effects of this embodiment are not impaired.

(Crosslinking agent)
The composition in this embodiment may contain a crosslinking agent as needed, from the viewpoint of suppressing intermixing, etc. The crosslinking agent that can be used in this embodiment is not particularly limited, but for example, those described in International Publication No. 2013/024778, International Publication No. 2013/024779, and International Publication No. 2018/016614 can be used. In this embodiment, the crosslinking agent can be used alone or in combination of two or more.

Specific examples of crosslinking agents usable in this embodiment include, but are not limited to, phenol compounds (excluding polycyclic polyphenol resins in this embodiment), epoxy compounds, cyanate compounds, amino compounds, benzoxazine compounds, acrylate compounds, melamine compounds, guanamine compounds, glycoluryl compounds, urea compounds, isocyanate compounds, and azide compounds. These crosslinking agents can be used individually or in combination of two or more. Among these, benzoxazine compounds, epoxy compounds, or cyanate compounds are preferred, and benzoxazine compounds are more preferred from the viewpoint of improving etching resistance. Melamine compounds and urea compounds are more preferred from the viewpoint of having good reactivity. Examples of melamine compounds include the compound represented by formula (a) (Nicalac MW-100LM (trade name), manufactured by Sanwa Chemical Co., Ltd.) and the compound represented by formula (b) (Nicalac MX270 (trade name), manufactured by Sanwa Chemical Co., Ltd.).

The phenol compound can be any known compound and is not particularly limited; however, from the viewpoint of heat resistance and solubility, aralkyl-type phenolic resins are preferred.

The epoxy compound can be any known compound and is not particularly limited, but preferably, from the viewpoint of heat resistance and solubility, it is a solid epoxy resin at room temperature, such as epoxy resins obtained from phenol aralkyl resins or biphenyl aralkyl resins.

The cyanate compound is not particularly limited as long as it has two or more cyanate groups in one molecule; known compounds can be used. In this embodiment, preferred cyanate compounds include those in which the hydroxyl groups of a compound having two or more hydroxyl groups in one molecule are substituted with cyanate groups. Furthermore, cyanate compounds having aromatic groups are preferred, and those in which the cyanate group is directly bonded to the aromatic group can be suitably used. Such cyanate compounds are not particularly limited, but examples include those with structures in which hydroxyl groups are substituted with cyanate groups, such as bisphenol A, bisphenol F, bisphenol M, bisphenol P, bisphenol E, phenol novolac resin, cresol novolac resin, dicyclopentadiene novolac resin, tetramethylbisphenol F, bisphenol A novolac resin, brominated bisphenol A, brominated phenol novolac resin, trifunctional phenol, tetrafunctional phenol, naphthalene-type phenol, biphenyl-type phenol, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, dicyclopentadiene aralkyl resin, alicyclic phenol, and phosphorus-containing phenol. Furthermore, the aforementioned cyanate compounds may be in the form of monomers, oligomers, or resins.

The amino compound can be any known compound and is not particularly limited, but 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, and 4,4'-diaminodiphenyl ether are preferred from the viewpoint of heat resistance and raw material availability.

The benzoxazine compound can be any known compound and is not particularly limited; however, P-d type benzoxazines obtained from bifunctional diamines and monofunctional phenols are preferred from the viewpoint of heat resistance.

The melamine compound can be any known compound and is not particularly limited, but hexamethylol melamine, hexamethoxymethyl melamine, compounds in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or mixtures thereof are preferred from the viewpoint of raw material availability.

The guanamine compound can be any known compound and is not particularly limited, but tetramethylolguanamine, tetramethoxymethylguanamine, compounds in which one to four methylol groups of tetramethylolguanamine are methoxymethylated, or mixtures thereof are preferred from the viewpoint of heat resistance.

The glycoluryl compound can be any known compound and is not particularly limited, but tetramethylol glycoluryl and tetramethoxyglycoluryl are preferred from the viewpoint of heat resistance and etching resistance.

The urea compound can be any known compound and is not particularly limited, but tetramethylurea and tetramethoxymethylurea are preferred from the viewpoint of heat resistance.

Furthermore, in this embodiment, from the viewpoint of improving crosslinkability, a crosslinking agent having at least one allyl group may be used. Among these, allylphenols such as 2,2-bis(3-allyl-4-hydroxyphenyl)propane, 1,1,1,3,3,3-hexafluoro-2,2-bis(3-allyl-4-hydroxyphenyl)propane, bis(3-allyl-4-hydroxyphenyl)sulfone, bis(3-allyl-4-hydroxyphenyl)sulfide, and bis(3-allyl-4-hydroxyphenyl)ether are preferred.

In the composition of this embodiment, the content of the crosslinking agent is not particularly limited, but it is preferably 5 to 50 parts by mass, and more preferably 10 to 40 parts by mass, per 100 parts by mass of the polycyclic polyphenol resin in this embodiment. By using the above preferred range, the occurrence of mixing with the resist layer tends to be suppressed, the anti-reflective effect is enhanced, and the film formation after crosslinking tends to be improved.

(Crosslinking accelerator)
The composition in this embodiment may optionally contain a crosslinking accelerator to promote the crosslinking and curing reactions.

The aforementioned crosslinking accelerator is not particularly limited as long as it promotes the crosslinking and curing reactions, but examples include amines, imidazoles, organophosphines, and Lewis acids. These crosslinking accelerators can be used individually or in combination of two or more. Among these, imidazoles or organophosphines are preferred, and from the viewpoint of lowering the crosslinking temperature, imidazoles are more preferred.

The aforementioned crosslinking accelerator can be any known agent and is not particularly limited, but examples include those described in International Publication No. 2018/016614. From the viewpoint of heat resistance and curing acceleration, 2-methylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole are particularly preferred.

The crosslinking accelerator content is typically preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, based on a total mass of 100 parts by mass of the composition.

(Radical polymerization initiator)
The composition in this embodiment may optionally contain a radical polymerization initiator. The radical polymerization initiator may be a photopolymerization initiator that initiates radical polymerization by light, or a thermal polymerization initiator that initiates radical polymerization by heat. The radical polymerization initiator may be at least one selected from the group consisting of, for example, ketone-based photopolymerization initiators, organic peroxide-based polymerization initiators, and azo-based polymerization initiators.

Such radical polymerization initiators are not particularly limited, and conventionally used ones can be appropriately employed. For example, those described in International Publication 2018/016614 can be cited. Among these, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and t-butylcumyl peroxide are particularly preferred from the viewpoint of raw material availability and storage stability.

The radical polymerization initiators used in this embodiment may be one of these used alone, or two or more used in combination, or they may be used in combination with other known polymerization initiators.

(Acid generator)
The composition in this embodiment may contain an acid generator as needed, from the viewpoint of further promoting the thermal crosslinking reaction. Known acid generators include those that generate acid by thermal decomposition and those that generate acid by light irradiation, and any of these can be used.

The acid generator is not particularly limited, but for example, one described in International Publication No. 2013/024779 can be used. In this embodiment, the acid generator can be used alone or in combination of two or more types.

In the composition of this embodiment, the content of the acid generator is not particularly limited, but it is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 40 parts by mass, per 100 parts by mass of the polycyclic polyphenol resin in this embodiment. By setting the content within this preferred range, the amount of acid generated tends to increase, thereby enhancing the crosslinking reaction, and the occurrence of mixing with the resist layer tends to be suppressed.

(Basic compounds)
Furthermore, the composition in this embodiment may contain a basic compound, for example, to improve storage stability.

Basic compounds act as quenchers against acid, preventing trace amounts of acid generated by the acid generator from advancing the crosslinking reaction. Examples of such basic compounds include, but are not limited to, primary, secondary, or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having carboxyl groups, nitrogen-containing compounds having sulfonyl groups, nitrogen-containing compounds having hydroxyl groups, nitrogen-containing compounds having hydroxyphenyl groups, alcoholic nitrogen-containing compounds, amide derivatives, and imide derivatives.

The basic compound used in this embodiment is not particularly limited, but for example, those described in International Publication No. 2013/024779 can be used. In this embodiment, the basic compound can be used alone or in combination of two or more.

In the composition of this embodiment, the content of the basic compound is not particularly limited, but it is preferably 0.001 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of the polycyclic polyphenol resin in this embodiment. By keeping it within this preferred range, storage stability tends to be improved without excessively impairing the crosslinking reaction.

(Other additives)
Furthermore, the composition in this embodiment may contain other resins and/or compounds for the purpose of imparting thermosetting properties or controlling absorbance. Examples of such other resins and/or compounds include, but are not limited to, naphthol resins, xylene resin naphthol-modified resins, phenol-modified resins of naphthalene resins, polyhydroxystyrene, dicyclopentadiene resins, (meth)acrylate, dimethacrylate, trimethacrylate, tetramethacrylate, resins containing heterocyclic rings such as vinylnaphthalene, polyacenaphthylene, biphenyl rings such as phenanthrenequinone and fluorene, thiophene, indene, etc., or resins that do not contain aromatic rings; rosin-based resins, cyclodextrins, adamantane(poly)ol, tricyclodecane(poly)ol and their derivatives, etc., or resins or compounds containing alicyclic structures.

[Coating process]
In the coating step performed in the resist underlayer film formation method according to this embodiment, a composition containing a resist underlayer film forming material selected from the group consisting of the above-mentioned aromatic compounds or resins thereof is coated onto a substrate.

The substrates that can be used in this embodiment are not particularly limited, but examples include semiconductor substrates such as silicon on which a silicon oxide film, silicon nitride film, or silicon oxidiznitride film is formed, silicon nitride substrates, quartz substrates, glass substrates (including alkali-free glass, low-alkali glass, and crystallized glass), and glass substrates on which an ITO film is formed. The coating procedure in the coating process is also not particularly limited; for example, the composition in this embodiment can be applied to the aforementioned substrates using an appropriate coating method such as a spinner or coater.

[Preheat treatment process]
In the preheating step performed in the resist underlayer film formation method according to this embodiment, the coated composition is heated to a temperature of 50°C to 300°C as described above. That is, a curing reaction occurs when the substrate coated with the composition in this embodiment is heated to a predetermined temperature, and a resist underlayer film precursor is formed.

The heating method in the preheat treatment process is not particularly limited, but for example, a hot plate can be used. The heating conditions are preferably 50°C to 300°C, more preferably 50°C to 250°C, and more preferably 50°C to 200°C. By heating at a temperature of 300°C or lower in the preheat treatment process, it is possible to suppress excessive oxidation of the resist underlayer film formation material even in an air atmosphere, while improving the heat resistance of the film due to curing. Therefore, by avoiding oxidation and decomposition of the film in subsequent heat treatment processes, carbonization by dehydration and dehydrogenation can be promoted, resulting in the formation of a resist underlayer film with a high carbon concentration and excellent etching resistance.

The heating time in the preheat treatment step is preferably 15 seconds or more, more preferably 30 seconds or more, and even more preferably 45 seconds or more. Furthermore, the heating time is preferably 20 minutes or less, more preferably 1,200 seconds or less, even more preferably 600 seconds or less, and even more preferably 300 seconds.

The atmosphere in the preheat treatment process is preferably an inert gas atmosphere containing nitrogen, argon, or a mixture thereof. Here, the oxygen concentration in the preheat treatment process is preferably less than 20%, and more preferably less than 5%. In this specification, the oxygen concentration is specified on a volume basis.

[Heat treatment process]
The heat treatment step performed in the resist underlayer film formation method according to this embodiment is carried out after the preheat treatment step described above. In the heat treatment step in this embodiment, heating is performed at a temperature of 400°C or higher and less than 800°C in an inert gas atmosphere with an oxygen concentration of less than 5%.
In the heat treatment process, the process is carried out in a low-oxygen atmosphere with an oxygen concentration of less than 5.0%, and the heating temperature is set to a temperature that does not cause thermal decomposition of the underlying film. This allows the hardening reaction of the film to proceed while suppressing excessive oxidation, thereby improving the thermal decomposition temperature and allowing the upper limit of the bake temperature to be set higher than when baking in air. If the heating temperature is below 400°C or above 800°C, the necessary properties of the resist underlying film may not be exhibited. Furthermore, within the temperature range in which the underlying film does not thermal decompose, a higher bake temperature can be achieved to increase the density of the formed film.
From the above viewpoint, the heating temperature in the heat treatment process is preferably 450°C or higher, more preferably 500°C or higher, and even more preferably 550°C or higher. Furthermore, the heating temperature is preferably 650°C or lower, and more preferably 600°C or lower.

The heating time in the heat treatment process is preferably 15 seconds to 20 minutes. More preferably, the heating time is 30 seconds or more, and even more preferably 45 seconds or more. Furthermore, the heating time is more preferably 1,200 seconds or less, even more preferably 600 seconds or less, and even more preferably 300 seconds or less.

The oxygen concentration during the heat treatment process should be less than 10.0%, preferably 5.0% or less, more preferably 1.0% or less, and even more preferably 0.1% or less. If the oxygen concentration during heating is high, oxidation of the resist underlayer film may progress, potentially preventing the resist underlayer film from exhibiting the necessary properties.

In this embodiment, the resist underlayer film is formed through the heat treatment process described above. However, if the composition in this embodiment contains a photosensitive acid generator, the curing process can be accelerated by combining exposure and heating to form the resist underlayer film. The radiation used for this exposure can be appropriately selected from electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and gamma rays, or particle beams such as electron beams, molecular beams, and ion beams, depending on the type of photosensitive acid generator.

The lower limit of the average thickness of the resist underlayer film formed is preferably 0.05 μm, more preferably 0.1 μm, and even more preferably 0.2 μm. The upper limit of the average thickness is preferably 5 μm, more preferably 3 μm, and even more preferably 2 μm.

<Pattern Formation Method>
The pattern formation method according to this embodiment includes the steps of: (i) forming a resist underlayer film on a substrate using the resist underlayer film formation method according to this embodiment; (ii) forming a silicon-containing intermediate layer by applying an intermediate layer formation composition containing silicon atoms onto the resist underlayer film and baking it; (iii) forming a resist film on the silicon-containing intermediate layer; (iv) forming a resist pattern by at least exposing and developing the resist film; and (v) dry etching the silicon-containing intermediate layer using a gas containing fluorocarbons, with the resist pattern as a mask. Because of this configuration, the pattern formation method according to this embodiment can form a pattern with good shape. That is, it can be preferably applied to pattern formation using a multilayer resist process for semiconductor devices where further miniaturization of patterns is progressing. The procedures for steps (ii) to (v) and the materials used in each step can be those known as described in, for example, Japanese Patent Application Publication No. 2020-30227.

The following examples and comparative examples will be shown to further describe this embodiment, but this embodiment is not limited to these.

^{1. ¹H} -NMR measurements were performed using a Bruker "Advance600II spectrum meter" under the following conditions.
Frequency: 400 MHz
Solvent: d6-DMSO
Internal standard: TMS
Measurement temperature: 23℃

(molecular weight)
LC-MS analysis was performed using a Water Acquisition UPLC/MALDI-Synapt HDMS.
(Polystyrene equivalent molecular weight)
Gel permeation chromatography (GPC) analysis was used to determine the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in polystyrene terms, and then the degree of dispersion (Mw/Mn) was calculated.
Equipment: Shodex GPC-101 (manufactured by Showa Denko Corporation)
Columns: KF-80M x 3
Eluent: THF 1mL/min
Temperature: 40℃

(Synthesis Example 1) Synthesis of R-DHN In a 500 mL container equipped with a stirrer, condenser, and burette, 16.8 g (105 mmol) of 2,6-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.) and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 30 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 110 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 27.3 g of the target resin (R-DHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 3578, Mw: 4793, and Mw/Mn: 1.34.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.7-9.8 (2H, O-H), 7.0-7.9 (4H, Ph-H)

(Synthesis Example 1-2) Synthesis of R-2,7DHN In a 500 mL container equipped with a stirrer, condenser, and burette, 16.8 g (105 mmol) of 2,7-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.) and 15.2 g (30 mmol) of monobutyl copper phthalate were charged. 40 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 110 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 24.7 g of the target resin (R-2,7DHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 2832, Mw: 3476, and Mw/Mn: 1.23.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.7-9.8 (2H, O-H), 7.0-7.9 (4H, Ph-H)

(Synthesis Example 1-3) Synthesis of R-2,3DHN The synthesis was carried out in the same manner as in Synthesis Example 1-2, except that 2,7-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.) was replaced with 2,3-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.), and 29.2 g of the target resin (R-2,3DHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 3124, Mw: 4433, and Mw/Mn: 1.42.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.5-9.6 (2H, O-H), 7.0-7.9 (4H, Ph-H)

(Synthesis Example 1-4) Synthesis of R-1,5DHN The synthesis was carried out in the same manner as in Synthesis Example 1-2, except that 2,7-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.) was replaced with 1,5-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.), and 25.8 g of the target resin (R-1,5DHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 2988, Mw: 3773, and Mw/Mn: 1.26.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.8-9.9 (2H, O-H), 7.1-8.0 (4H, Ph-H)

(Synthesis Example 1-5) Synthesis of R-1,6DHN The synthesis was carried out in the same manner as in Synthesis Example 1-2, except that 2,7-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.) was replaced with 1,6-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.), and 23.2 g of the target resin (R-1,6DHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 2687, Mw: 3693, and Mw/Mn: 1.37.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.8-9.9 (2H, O-H), 6.8-7.9 (4H, Ph-H)

(Synthesis Example 1-6) Synthesis of R-FLBNDHN In a container with an internal volume of 500 mL equipped with a stirrer, condenser and burette, 6,6'-(9H
47.3 g (105 mmol) of -fluorene-9,9-diyl)bis(2-naphthol) (reagent manufactured by Kanto Chemical Co., Ltd.), 16.8 g (105 mmol) of 2,6-dihydroxynaphthalene (reagent manufactured by Kanto Chemical Co., Ltd.), and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 120 mL of 4-butyrolactone was added as a solvent, and the reaction mixture was stirred at 120°C for 8 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 150 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 300 mL of distilled water was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 51.6 g of the target resin (R-FLBNDHN) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4128, Mw: 5493, and Mw/Mn: 1.33.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.7-9.9 (2H, O-H), 9.1-9.3 (2H, O-H), 7.1-8.0 (22H, Ph-H)

In other words, R-FLBNDHN is 6,6'-(9H-fluorene-9,9-diyl)
A homopolymer of bis(2-naphthol), a homopolymer of 2,6-dihydroxynaphthalene, and 6,6'-(9H-fluorene-9,9-diyl)bis(2-naphthol) and 2,
It was a mixture containing a copolymer of 6-dihydroxynaphthalene.

(Synthesis Example 2) Synthesis of R-BiF In a 500 mL container equipped with a stirrer, condenser, and burette, 19.2 g (105 mmol) of 4,4-biphenol (reagent manufactured by Kanto Chemical Co., Ltd.) and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 80 mL of 4-butyrolactone was added as a solvent, and the reaction mixture was stirred at 120 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 21.2 g of the target resin (R-BiF) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4128, Mw: 5493, and Mw/Mn: 1.33.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.1 to 9.3 (2H, O-H), 7.1 to 8.2 (6H, Ph-H)

(Synthesis Example 3) Synthesis of BisN-1 In a 500 mL container equipped with a stirrer, condenser, and burette, 20.0 g (200 mmol) of 1,4-dihydroxybenzene (reagent manufactured by Kanto Chemical Co., Ltd.), 18.2 g (100 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 100 mL of 1,4-dioxane were charged. 5 mL of 95% sulfuric acid was added, and the mixture was stirred at 100°C for 6 hours to carry out the reaction. Next, the reaction solution was neutralized with a 24% sodium hydroxide aqueous solution, and 50 g of pure water was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. After drying the obtained solid, separation and purification by column chromatography were performed to obtain 20.6 g of the target compound (BisN-1) represented by the following formula.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that it has the chemical structure shown in the formula below.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.4 (2H, O-H), 7.2-8.1 (13H, Ph-H), 6.5 (1H, C-H)
Furthermore, LC-MS analysis confirmed that the molecular weight is 366.1, corresponding to the chemical structure shown below.

(Synthesis Example 3-1) Synthesis of RBisN-1 In a 500 mL container equipped with a stirrer, condenser, and burette, 38.0 g (105 mmol) of BisN-1 and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 100 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 100 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 28.2 g of the target resin (RBisN-1) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 3762, Mw: 4905, and Mw/Mn: 1.30.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.3 to 9.6 (2H, O-H), 7.2 to 8.7 (17H, Ph-H), 6.8 (1H, C-H)

(Synthesis Example 4) Synthesis of BisN-2 In a 500 mL container equipped with a stirrer, condenser, and burette, 32.0 g (20 mmol) of 2,6-naphthalenediol (reagent from Sigma-Aldrich), 18.2 g (100 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 200 mL of 1,4-dioxane were charged. 10 mL of 95% sulfuric acid was added, and the mixture was stirred at 100°C for 6 hours to carry out the reaction. Next, the reaction solution was neutralized with a 24% aqueous sodium hydroxide solution, 100 g of pure water was added to precipitate the reaction product, and after cooling to room temperature, the product was separated by filtration. After drying the obtained solid, separation and purification by column chromatography were performed to obtain 25.5 g of the target compound (BisN-2) represented by the following formula.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that the compound has the chemical structure shown in the formula below. Additionally, the substitution position of 2,6-dihydroxynaphthol at position 1 was confirmed by the doublet signal of the protons at positions 3 and 4.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.7 (2H, O-H), 7.2-8.5 (19H, Ph-H), 6.6 (1H, C-H)
Furthermore, LC-MS analysis confirmed that the molecular weight is 466.5, corresponding to the chemical structure shown below.

(Synthesis Example 4-1) Synthesis of RBisN-2 In a 500 mL container equipped with a stirrer, condenser, and burette, 50 g (105 mmol) of BisN-2 and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 100 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 100 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 38.2 g of the target resin (RBisN-2) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4232, Mw: 5502, and Mw/Mn: 1.30.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.3 to 9.7 (2H, O-H), 7.2 to 8.5 (17H, Ph-H), 6.7 to 6.9 (1H, C-H)

(Synthesis Example 4A) Synthesis of BisN-5 The procedure was the same as in Synthesis Example 4, except that 18.2 g (100 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was replaced with 9.1 g (100 mmol) of 4-toluylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 23.2 g of the target compound (BisN-3) represented by the following formula was obtained.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that the compound has the chemical structure shown in the formula below. Additionally, the substitution position of 2,6-dihydroxynaphthol at position 1 was confirmed by the doublet signal of the protons at positions 3 and 4.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.7 (2H, O-H), 7.2-8.4 (14H, Ph-H), 6.6 (1H, C-H), 1.9 (3H, C-H3)
Furthermore, LC-MS analysis confirmed that the molecular weight is 404.1, corresponding to the chemical structure shown below.

(Synthesis Example 4A-1) Synthesis of RBisN-5 Except for replacing BisN-2 in Synthesis Example 4-1 with BisN-5 obtained in Synthesis Example 4A, the same procedure as in Synthesis Example 4-1 was used to obtain 32.1 g of the target resin (RBisN-5) having the structure represented by the following formula.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 3452, Mw: 4802, and Mw/Mn: 1.39.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.3 to 9.7 (2H, O-H), 7.2 to 8.5 (12H, Ph-H), 6.7 to 6.9 (1H, C-H), 1.9 (3H, C-H3)

(Synthesis Example 4B) Synthesis of BisN-6 The procedure was the same as in Synthesis Example 4, except that 18.2 g (100 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was replaced with 18.8 g (100 mmol) of 4-cyclohexylbenzaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 33.5 g of the target compound (BisN-6), represented by the following formula, was obtained.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that the compound has the chemical structure shown in the formula below. Additionally, the substitution position of 2,6-dihydroxynaphthol at position 1 was confirmed by the doublet signal of the protons at positions 3 and 4.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.7 (2H, O-H), 7.2 to 8.4 (14H, Ph-H), 6.6 (1H, C-H), 2.5 to 2.6 (6H, C6-H5)
Furthermore, LC-MS analysis confirmed that the molecular weight is 472.2, corresponding to the chemical structure shown below.

(Synthesis Example 4B-1) Synthesis of RBisN-6 Except for replacing BisN-2 in Synthesis Example 4-1 with BisN-6 obtained in Synthesis Example 4B, the same procedure as in Synthesis Example 4-1 was used to obtain 40.4 g of the target resin (RBisN-6) having the structure represented by the following formula.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 3672, Mw: 5080, and Mw/Mn: 1.38.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.3 to 9.7 (2H, O-H), 7.2 to 8.5 (12H, Ph-H), 6.7 (1H, C-H), 2.5 to 2.7 (6H, C6-H5)

(Synthesis Example 4C) Synthesis of BisN-7 The aromatic hydroxy compound of Synthesis Example 4C was synthesized by performing the same procedure as in Synthesis Example 4, except that 18.2 g (100 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was replaced with 2-naphthaldehyde (manufactured by Kanto Chemical Co., Ltd.) g (100 mmol). 33.5 g of the target resin (RBisN-7), represented by the following formula, was obtained in the same manner as in Synthesis Example 4-1, except that the aromatic hydroxy compound was used.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4174, Mw: 5280, and Mw/Mn: 1.26.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that the compound has the chemical structure shown in the formula below. Additionally, the substitution position of 2,6-dihydroxynaphthol at position 1 was confirmed by the doublet signal of the protons at positions 3 and 4.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.6 (2H, O-H), 7.0 to 8.5 (19H, Ph-H), 6.6 (1H, C-H), 2.5H, Ph-H), 6.7 (1H, C-H)

(Synthesis Example 5) Synthesis of BiF-1 A 1 L container equipped with a stirrer, condenser, and burette was prepared. 150 g (800 mmol) of 4,4-biphenol (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), 75 g (410 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 300 mL of propylene glycol monomethyl ether were charged into this container. 19.5 g (105 mmol) of p-toluenesulfonic acid (reagent manufactured by Kanto Chemical Co., Ltd.) was added to prepare the reaction solution. The reaction solution was stirred at 90°C for 3 hours. Next, the reaction solution was neutralized with a 24% sodium hydroxide aqueous solution, 100 g of distilled water was added to precipitate the reaction product, and after cooling to 5°C, the product was separated by filtration. After drying the solid obtained by filtration, separation and purification were performed by column chromatography to obtain 25.8 g of the target compound (BiF-1) represented by the following formula.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that it has the chemical structure shown in the formula below.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.4 (4H, O-H), 6.8-7.8 (22H, Ph-H), 6.2 (1H, C-H)
Furthermore, LC-MS analysis confirmed that the molecular weight is 536.2, corresponding to the chemical structure shown below.

(Synthesis Example 5-1) Synthesis of RBiF-1 In a 500 mL container equipped with a stirrer, condenser, and burette, 55.0 g (105 mmol) of BiF-1 and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 100 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 100 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 200 mL of methanol was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 34.3 g of the target resin (RBiF-1) having the structure represented by the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4532, Mw: 5698, and Mw/Mn: 1.26.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.4-9.7 (4H, O-H), 6.8-8.1 (20H, Ph-H), 6.3-6.5 (1H, C-H)

(Synthesis Example 5A) Synthesis of BiF-3 Except that 75 g (410 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) in Synthesis Example 5 was replaced with 4-toluylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 26.3 g of the target compound (BiF-3) represented by the following formula was obtained in the same manner as in Synthesis Example 5.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that it has the chemical structure shown in the formula below.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.4 (4H, O-H), 6.8-7.8 (18H, Ph-H), 6.2 (1H, C-H), 1.8 (3H, C-H3)
Furthermore, LC-MS analysis confirmed that the molecular weight is 474.5, corresponding to the chemical structure shown below.

(Synthesis Example 5A-1) Synthesis of RBiF-3 Except for replacing BiF-1 in Synthesis Example 5-1 with BiF-3 obtained in Synthesis Example 5A, the same procedure as in Synthesis Example 5-1 was used to obtain 31.2 g of the target resin (RBiF-3) having the structure represented by the following formula.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4232, Mw: 5288, and Mw/Mn: 1.25.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.4-9.7 (4H, O-H), 6.8-8.1 (16H, Ph-H), 6.3-6.5 (1H, C-H), 1.8-1.9 (3H, C-H3)

(Synthesis Example 5B) Synthesis of BiF-4 Except that 75 g (410 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) in Synthesis Example 5 was replaced with 4-cyclohexylbenzaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 32.1 g of the target compound (BiF-4) represented by the following formula was obtained in the same manner as in Synthesis Example 5.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that it has the chemical structure shown in the formula below.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.4 (4H, O-H), 6.8 to 7.8 (18H, Ph-H), 6.2 (1H, C-H), 2.4 to 2.6 (10H, C6H10)
Furthermore, LC-MS analysis confirmed that the molecular weight is 542.7, corresponding to the chemical structure shown below.

(Synthesis Example 5B-1) Synthesis of RBiF-4 Except for replacing BiF-1 in Synthesis Example 5-1 with BiF-4 obtained in Synthesis Example 5B, the same procedure as in Synthesis Example 5-1 was used to obtain 29.5 g of the target resin (RBiF-4) having the structure represented by the following formula.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4431, Mw: 5568, and Mw/Mn: 1.26.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.4-9.7 (4H, O-H), 6.8-8.1 (16H, Ph-H), 6.3-6.5 (1H, C-H), 2.4-2.9 (10H, C6H10)

(Synthesis Example 5C) Synthesis of BiF-5 Except that 75 g (410 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was replaced with 2-naphthaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.) in the same procedure as in Synthesis Example 5, 33.5 g of the target compound (BiF-5) represented by the following formula was obtained.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR, confirming that it has the chemical structure shown in the formula below.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.4 (4H, O-H), 6.8-7.8 (21H, Ph-H), 6.2 (1H, C-H)
Furthermore, LC-MS analysis confirmed that the molecular weight is 510.6, corresponding to the chemical structure shown below.

(Synthesis Example 5C-1) Synthesis of RBiF-5 Except for replacing BiF-1 in Synthesis Example 5-1 with BiF-5 obtained in Synthesis Example 5C, the same procedure as in Synthesis Example 5-1 was used to obtain 29.5 g of the target resin (RBiF-4) having the structure represented by the following formula.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 4133, Mw: 5462, and Mw/Mn: 1.32.
When the obtained resin was subjected to NMR measurement under the above measurement conditions, the following peaks were found, confirming that it has the chemical structure shown in the formula below.
δ (ppm) 9.4 to 9.7 (4H, O-H), 6.8 to 8.1 (19H, Ph-H), 6.3 to 6.5 (1H, C-H)

(Example 5D) Synthesis of TriF-4 A 1000 mL container equipped with a stirrer, condenser, and burette was prepared. 10 g (53.7 mmol) of 4,4-biphenol (reagent manufactured by Tokyo Chemical Co., Ltd.), 98 g (538 mmol) of 4-biphenylaldehyde (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 400 mL of propylene glycol monomethyl ether were charged into this container. 2.7 g (26.9 mmol) of concentrated sulfuric acid (96% by mass, reagent manufactured by Kanto Chemical Co., Ltd.) was added to prepare the reaction solution. The reaction solution was stirred at 100°C for 5 hours. Next, the reaction solution was added to 2 L of deionized water to precipitate the reaction product, and the mixture was cooled to room temperature. Then, 49 g (26.7 mmol) of aqueous sodium hydroxide solution (24% by mass) was added to neutralize the mixture, and the product was separated by filtration. The solid obtained by filtration was dried, then dissolved in 400 mL of butyl acetate and washed six times with 400 mL of 5% sodium carbonate aqueous solution. After washing, 400 mL of toluene was added to the organic layer and stirred, and the precipitated solid was recovered by filtration after concentration under reduced pressure at 100°C. The obtained solid was dried under reduced pressure to obtain 72 g of the target resin (TriF-4) represented by the following formula.
The polystyrene-equivalent molecular weight was measured using the above method, and the results were Mn: 4523, Mw: 5642, and Mw/Mn: 1.24.
Furthermore, the following peaks were found by 400 MHz- ^1H -NMR.
^1H -NMR: (d-DMSO, internal standard TMS)
δ (ppm) 9.3-9.4 (8.3H, O-H), 6.7-7.7 (50.2H, Ph-H), 6.0-6.2 (3.2H, C-H)

From the above ^1H -NMR and LC-MS results, it was confirmed that the target resin obtained in Example 5 is a resin having the chemical structure of the following formula.

(Synthesis Example 6) Synthesis of DB-1 (a) Production of calcium dibenzochrysenesulfonate In a 1 L four-necked flask equipped with a mechanical stirrer, 20 g (0.06 mol, HPLC purity: 99.8%) of dibenzo[g,p]chrysene and 200 g (1.94 mol) of 95% sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were charged and reacted with stirring at an internal temperature of 80°C for 2 hours while maintaining the temperature using a water bath. As a result, the contents became a uniform gray viscous liquid.
While cooling the flask containing the contents obtained above in an ice bath, 400 g of distilled water was added. During this addition, the internal temperature was monitored to maintain a temperature below 40°C to prevent the internal temperature from exceeding 40°C due to exothermic reaction. Next, 154.4 g (2.08 mol) of powdered calcium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the flask containing the distilled water. During this addition, the internal temperature was monitored to maintain a temperature below 45°C to prevent the internal temperature from exceeding 45°C due to exothermic reaction. Upon this addition, calcium sulfate precipitated as a white solid, and the contents became a slurry. The solution was alkaline.
The slurry obtained above was subjected to suction filtration using a stainless steel Buchner funnel and No. 2 filter paper, and the filtrate (pale yellow liquid) was recovered. Furthermore, the solid residue (mainly calcium sulfate) was washed with 350 g of distilled water, and the washing solution was also recovered. This solution, along with the above filtrate, was concentrated under reduced pressure using a rotary evaporator. As a result, 36.5 g of calcium dibenzochrysenesulfonate, a pale yellow powdery solid, was obtained (yield 82.7%). Based on the results of LC/MS analysis of hydroxydibenzochrysene described later, the calcium dibenzochrysenesulfonate is considered to be a mixture in which 98% is 4-substituted dibenzochrysenesulfonate and the remainder is 3-substituted dibenzochrysenesulfonate.
(b) Preparation of hydroxydibenzochrysene 14.0 g (0.212 mol) of 85% potassium hydroxide granules (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a 100 mL nickel cylindrical container and heated and melted on a hot plate (400°C). Subsequently, 4.0 g (0.0055 mol) of the calcium dibenzochrysene sulfonate salt (mixture 8) obtained above was added. During this addition, the calcium dibenzochrysene sulfonate salt was added to the nickel cylindrical container over 30 minutes, and the reaction was promoted by stirring with a stainless steel spoon at the time of addition. Furthermore, stirring was continued for 30 minutes after the completion of the addition of calcium dibenzochrysene sulfonate salt. As a result, a reddish-brown viscous liquid was obtained.
The reddish-brown, viscous liquid obtained above (the contents of the nickel cylindrical container) was poured while still hot into a 200 mL stainless steel cup and allowed to cool and solidify. Subsequently, 40 g of distilled water was added to this stainless steel cup to dissolve the solid, yielding a slightly cloudy reddish-brown liquid.
Next, the reddish-brown liquid was transferred to a 200 mL glass beaker, and 35% hydrochloric acid (Wako Pure Chemical Industries, Ltd.) was added while stirring with a magnetic stirring device to obtain a contents containing a brown solid. During this addition, the pH was measured with a pH meter, and the addition was continued until the pH of the contents reached pH 3. It was confirmed that the brown solid precipitated at the time of neutralization.
Subsequently, 30 g of ethyl acetate (Wako Pure Chemical Industries, Ltd.) was added to the contents obtained above while stirring to dissolve the brown solid. The resulting liquid was then allowed to stand to separate into an organic phase and an aqueous phase, and the organic phase was separated. The separated organic layer was filtered through a glass funnel and No. 2 filter paper to remove insoluble matter, and then concentrated under reduced pressure using a rotary evaporator to obtain 1.6 g of brown powdery solid (yield 73.9%). The brown powdery solid obtained in the above procedure was subjected to LC/MS analysis, and the brown powdery solid was found to be 98% pure tetrasubstituted hydroxydibenzochrysene.

(Synthesis Example 6-1) Synthesis of RDB-1 In a 500 mL container equipped with a stirrer, condenser, and burette, 80.0 g of DB-1 and 10.1 g (20 mmol) of monobutyl copper phthalate were charged. 100 mL of 1-butanol was added as a solvent, and the reaction mixture was stirred at 100 °C for 6 hours. After cooling, the precipitate was filtered, and the resulting crude product was dissolved in 100 mL of ethyl acetate. Next, 5 mL of hydrochloric acid was added, and after stirring at room temperature, the mixture was neutralized with sodium bicarbonate. The ethyl acetate solution was concentrated, and 300 mL of heptane was added to precipitate the reaction product. After cooling to room temperature, the product was separated by filtration. By drying the obtained solid, 64.5 g of the target resin (RDB-1) having the structure represented by the group shown in the following formula was obtained.
The obtained resin was measured for polystyrene-equivalent molecular weight using the method described above, and the results were Mn: 2512, Mw: 3298, and Mw/Mn: 1.31.

(Comparative Synthesis Example 1)
A 10 L four-necked flask with a removable bottom was prepared, equipped with a Liebig condenser, thermometer, and stirring blade. In this flask, 1.09 kg (7 mol, manufactured by Mitsubishi Gas Chemical Co., Ltd.) of 1,5-dimethylnaphthalene, 2.1 kg of 40% formalin aqueous solution (28 mol as formaldehyde, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 0.97 mL of 98% sulfuric acid (manufactured by Kanto Chemical Co., Ltd.) were charged under a nitrogen stream. The reaction was carried out under atmospheric pressure at 100°C under reflux for 7 hours. Subsequently, 1.8 kg of ethylbenzene (reagent grade, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the reaction mixture as a diluent, and after standing, the aqueous phase was removed. Further neutralization and washing with water were performed, and ethylbenzene and unreacted 1,5-dimethylnaphthalene were removed by distillation under reduced pressure to obtain 1.25 kg of light brown solid dimethylnaphthaleneformaldehyde resin.

Next, a 0.5 L four-necked flask equipped with a Liebig condenser, thermometer, and stirring blade was prepared. Into this four-necked flask, under a nitrogen stream, 100 g (0.51 mol) of the dimethylnaphthaleneformaldehyde resin obtained as described above and 0.05 g of p-toluenesulfonic acid were charged. The mixture was heated to 190°C for 2 hours and then stirred. Subsequently, 52.0 g (0.36 mol) of 1-naphthol was added, and the mixture was further heated to 220°C for 2 hours. After solvent dilution, neutralization and washing with water were performed, and the solvent was removed under reduced pressure to obtain 126.1 g of a dark brown solid modified resin (CR-1).

<Formation of the underlayer film of the resist>
[Examples]
Compositions for forming resist underlayer films were prepared from the resins obtained in the above synthesis examples to have the compositions shown in Tables 1 and 2, and were coated onto a silicon wafer substrate by spin coating. Subsequently, the substrates were left to stand for 60 seconds in a predetermined oxygen concentration atmosphere without contact with a hot plate, and then preheated on a hot plate at 200°C to 300°C for 60 seconds (the conditions are shown in Tables 1 and 2) to form a resist underlayer film precursor with an average thickness of 200 nm on the substrate. Subsequently, the substrates were heated (fired) at 550 to 750°C for 120 seconds in a low oxygen concentration atmosphere (oxygen concentration less than 5.0%) (the conditions are shown in Tables 1 and 2) to obtain a substrate with a resist underlayer film.

[Comparative Example]
Similarly, each resist underlayer film formation composition was prepared to have the composition shown in Tables 3-4 and applied to a silicon wafer substrate by spin coating. Then, after being left to stand for 60 seconds in a predetermined oxygen concentration atmosphere without contact with a hot plate, a preheat treatment was performed on a hot plate at 320-350°C for 60 seconds, and then a heat treatment (sintering) was performed at 550-800°C for 120 seconds under each oxygen concentration condition to obtain substrates with resist underlayer films.

Separately, for heat resistance evaluation, a resist underlayer film formation composition prepared to have the same composition as each example and comparative example was applied to a silicon wafer substrate by spin coating. Without preheating, the substrate was heated (fired) at 400°C for 60 seconds in an air atmosphere to obtain a substrate with a resist underlayer film for heat resistance evaluation.

The following organic solvents and novolac resins were used.
Organic solvents: Cyclohexanone (CHN), Propylene glycol monomethyl ether acetate (PGMEA)
Novolac resin: PSM4357, manufactured by Gun-ei Chemical Co., Ltd.

The substrates with the resist underlayer film obtained above were evaluated using the following procedure. The evaluation results, along with the firing conditions, are shown in Tables 1 and 2 below.

[Heat resistance]
For the resist-backed substrates obtained above, the film thickness was measured after heating (firing) using an interferometric film thickness meter, and the film thickness reduction rate was calculated relative to the film thickness of the resist-backed substrate used for heat resistance evaluation as described above. Heat resistance was evaluated as follows: "A" (excellent) if the film thickness reduction rate was less than 20%, "B" (good) if it was between 20% and 40%, and "C" (poor) if it was 40% or more.

[Evaluation of etching resistance]
Etching resistance was evaluated using the following procedure.
First, a novolac underlayer film for etching resistance evaluation was prepared using novolac (PSM4357, manufactured by Gun-ei Chemical Co., Ltd.) instead of the resin used in the example, and under the same conditions as the example, except that the firing conditions were the same as in the example, with no preheat treatment performed and the film being heated (fired) at 400°C for 60 seconds in an air atmosphere. Then, an etching test was performed on this novolac underlayer film under the following conditions, and the etching rate was measured.
[Etching conditions]
Etching equipment: RIE-10NR manufactured by Samco International Corporation
Output: 50W
Pressure: 20 Pa
Time: 2 min
Etching gas flow rate: Ar gas flow rate: CF _{, 4} gas flow rate: O _{, 2} gas flow rate = 50:5:5 (sccm)

Next, the etching test described above was performed on the underlying films of the examples and comparative examples in the same manner, and the etching rate was measured.
Then, using the etching rate obtained from the novolac underlayer film for etching resistance evaluation as a reference, the etching resistance was evaluated according to the following evaluation criteria.
[Evaluation Criteria]
A: Etching rate less than -10% compared to the underlying novolac film. B: Etching rate between -10% and +5% compared to the underlying novolac film.
C: Etching rate is more than +5% compared to the underlying novolac film.

[Carbon concentration]
The carbon concentration was measured by organic elemental analysis.
Equipment: CHN Coder MT-6 (manufactured by Yanaco Analytical Industries Co., Ltd.)
[Evaluation Criteria]
A: 89.0% by mass or more B: Less than 89.0% by mass

As can be seen from the results in Tables 1 and 2, the resist underlayer film formation method of the example allowed for the formation of a resist underlayer film with excellent heat resistance and etching resistance by adjusting the heating temperature in the preheat treatment step, the oxygen concentration in the heating step, and the heating temperature to the desired range. In contrast, in the comparative examples shown in Tables 3 and 4, either the heating temperature in the preheat treatment step, the oxygen concentration in the heating step, or the heating temperature was outside the desired range, resulting in poor etching resistance, and the carbon concentration after the heating step also did not meet the desirable range. Furthermore, a tendency for decreased heat resistance was observed.

The present invention's method for forming a resist underlayer film can produce a resist underlayer film with excellent etching resistance. Furthermore, the pattern formation method of the present invention, by using the aforementioned resist underlayer film with excellent etching resistance, can form a pattern with a good shape. Therefore, these methods are suitably used for pattern formation using multilayer resist processes in semiconductor devices where further miniaturization of patterns is progressing.

Claims (10)

A step of coating a substrate with a composition containing a polycyclic polyphenol resin (excluding polyphenol resins represented by the following formula (A-14)) in which repeating units are linked by direct bonds between aromatic rings,
A preheat treatment step in which the applied composition is heated to a temperature of 50°C or higher and 300°C or lower,
After the aforementioned preheat treatment step, a heat treatment step is performed in which the material is heated at a temperature of 450°C or higher and less than 800°C in an inert gas atmosphere with an oxygen concentration of less than 5%.
Includes,
A method for forming a resist underlayer film, wherein the resin comprises a polycyclic polyphenol resin having repeating units derived from an aromatic hydroxy compound represented by formula (1B) .
(In formula (1B), A represents a benzene ring or a fused ring. Furthermore, each R0 ^is independently an optionally substituted alkyl group having 1 to 40 carbon atoms, an optionally substituted aryl group having 6 to 40 carbon atoms, an optionally substituted alkenyl group having 2 to 40 carbon atoms, an optionally substituted alkynyl group having 2 to 40 carbon atoms, an optionally substituted alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, where at least one of R0 ^is a hydroxyl group and m is an integer from 0 to 9.) A step of coating a substrate with a composition containing a polycyclic polyphenol resin (excluding polyphenol resins represented by the following formula (A-14)) in which repeating units are linked by direct bonds between aromatic rings,
A preheat treatment step in which the applied composition is heated to a temperature of 50°C or higher and 300°C or lower,
After the aforementioned preheat treatment step, a heat treatment step is performed in which the material is heated at a temperature of 450°C or higher and less than 800°C in an inert gas atmosphere with an oxygen concentration of less than 5%.
Includes,
The aforementioned resin is a resin having a structure represented by the following formula (2A):
The resin having the structure represented by formula (2A) is a resin having the structure represented by the following formula (2),
A method for forming a resist underlayer film, wherein the resin having the structure represented by formula (2) is a resin having the structure represented by the following formula (2-1).
(In formula (2A), X is an oxygen atom, a sulfur atom, a single bond, or no bridge, R ^a R is a 2n valent group or single bond having 1 to 40 carbon atoms, ^b Each of these is independently an alkyl group having 1 to 40 carbon atoms which may have substituents, an aryl group having 6 to 40 carbon atoms which may have substituents, an alkenyl group having 2 to 40 carbon atoms which may have substituents, an alkynyl group having 2 to 40 carbon atoms which may have substituents, an alkoxy group having 1 to 40 carbon atoms which may have substituents, a halogen atom, a thiol group, or a hydroxyl group, where n is an integer from 1 to 4 and p is independently an integer from 0 to 2. ^c It is a single bond, m ² Each of these is an independent integer between 0 and 8. Here, R ^b Of these, at least one is a group containing one or more selected from hydroxyl groups and thiol groups, and all m ² (They cannot both be zero at the same time.)
(In equation (2), X, n, and p are the same as those explained in equation (2A) above, and R ¹ R in formula (2A) above is ^a It is synonymous with R ² Each of these is independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, R ³ R in formula (2A) above is ^c It is synonymous with m ² This is equivalent to what was explained in formula (2A) above. Here, R ² At least one of them is selected from hydroxyl groups and thiol groups, and all m ² (They cannot both be zero at the same time.)
(In formula (2-1), Z is an oxygen atom or a sulfur atom, and R ¹ , R ² , R ³ , m ² , p and n are the same as those explained in formula (2) above, where R ² At least one of them is selected from hydroxyl groups and thiol groups, and all m ² (They cannot both be zero at the same time.) A step of coating a substrate with a composition containing a polycyclic polyphenol resin (excluding polyphenol resins represented by the following formula (A-14)) in which repeating units are linked by direct bonds between aromatic rings,
A preheat treatment step in which the applied composition is heated to a temperature of 50°C or higher and 300°C or lower,
After the aforementioned preheat treatment step, a heat treatment step is performed in which the material is heated at a temperature of 450°C or higher and less than 800°C in an inert gas atmosphere with an oxygen concentration of less than 5%.
Includes,
The aforementioned resin is a resin having a structure represented by the following formula (2A):
A method for forming a resist underlayer film, wherein the resin having the structure represented by formula (2A) is a resin having the structure represented by the following formula (4).
(In formula (2A), X is an oxygen atom, a sulfur atom, a single bond, or no bridge, R ^a R is a 2n valent group or single bond having 1 to 40 carbon atoms, ^b Each of these is independently an alkyl group having 1 to 40 carbon atoms which may have substituents, an aryl group having 6 to 40 carbon atoms which may have substituents, an alkenyl group having 2 to 40 carbon atoms which may have substituents, an alkynyl group having 2 to 40 carbon atoms which may have substituents, an alkoxy group having 1 to 40 carbon atoms which may have substituents, a halogen atom, a thiol group, or a hydroxyl group, where n is an integer from 1 to 4 and p is independently an integer from 0 to 2. ^c It is a single bond, m ² Each of these is an independent integer between 0 and 8. Here, R ^b Of these, at least one is a group containing one or more selected from hydroxyl groups and thiol groups, and all m ² (They cannot both be zero at the same time.)
(In formula (4), R ¹ , p and n are equivalent to those explained in formula (2A) above, and R ⁵ and R ⁶ Each of these is independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, an alkoxy group having 1 to 40 carbon atoms, a halogen atom, a thiol group, or a hydroxyl group, m ⁵ Each of these is an independent integer between 0 and 8, and m ⁶ Each of these is an independent integer from 0 to 9. Here, R ⁵ and R ⁶ At least one selected from is one of the hydroxyl group and thiol group, and all m ⁵ and m ⁶ It is impossible for both to be zero at the same time. ³ R in formula (2A) above is ^c (This is synonymous with...) A method for forming a resist underlayer film according to any one of claims 1 to 3 , wherein in the preheat treatment step, the composition is heated in an inert gas atmosphere with an oxygen concentration of less than 5%. The method for forming a resist underlayer film according to claim 2 or 3, wherein R ^a or R ¹ is a group represented by R ^A - R ^B , where R ^A is a methine group and R ^B is an aryl group having 6 to 30 carbon atoms, which may have substituents. The method for forming a resist underlayer film according to claim 1 , wherein A in formula (1B) is a condensed ring. The method for forming a resist underlayer film according to any one of claims 1 to 6 , wherein the resin further comprises a modified portion derived from a crosslinking reactive compound. The method for forming a resist underlayer film according to claim 7 , wherein the crosslinking reactive compound is an aldehyde or a ketone. A method for forming a resist underlayer film according to any one of claims 1 to 8 , wherein the weight-average molecular weight of the resin is 1,000 to 1,000,000. A method for forming a resist underlayer film according to any one of claims 1 to 9 , comprising the step of forming the resist underlayer film on the substrate,
A step of forming a silicon-containing intermediate layer by coating a silicon atom-containing intermediate layer-forming composition onto the resist underlayer film and baking it,
The steps include forming a resist film on the silicon-containing intermediate layer,
The steps include at least exposing and developing the resist film to form a resist pattern,
Using the resist pattern as a mask, a step is performed to dry etch the silicon-containing intermediate layer using a gas containing fluorocarbons,
A pattern formation method, including the following.