JP7342563B2 - Pattern forming composition and pattern forming method - Google Patents

Description

The present invention relates to a pattern forming composition and a pattern forming method.

Electronic devices such as semiconductors are required to have higher definition through miniaturization. Further, diversification of shapes of semiconductor device patterns is also being considered. Methods for forming such patterns include a double patterning method, a lithography method using an electron beam, a nanoimprint method, and a directed self-assembly material (hereinafter also referred to as a self-assembled composition for pattern formation). A pattern forming method using self-organization is known.

Self-assembled compositions for pattern formation self-assemble through phase separation, so there is no need for expensive electron beam lithography equipment, and there is no complication in the patterning process seen in double patterning methods, resulting in lower costs. It has the above advantages. As a self-assembled composition for pattern formation, for example, diblock copolymers such as polystyrene-polymethyl methacrylate (PS-PMMA) are known (for example, Patent Document 1).

The use of materials other than PS-PMMA as a self-assembled composition for pattern formation is also being considered. For example, Patent Document 2 discloses a self-assembled composition for pattern formation that has a main chain of a styrene polymer, an acrylic polymer, or the like, and has a group containing a hetero atom at the end of the main chain.

US2012/0241411 A1 JP 2014-5325 Publication

After forming a pattern using the self-assembled composition for pattern formation as described above, an etching process may be performed to further process the pattern shape onto a silicon wafer substrate using the pattern as a protective film. However, in the conventional method, the etching processability when processing a pattern shape on a substrate may be poor, which has been a problem.

Therefore, in order to solve the problems of the prior art, the present inventors conducted studies with the aim of providing a pattern-forming composition that can form a pattern-forming film that exhibits excellent etching processability. I proceeded.

As a result of intensive studies to solve the above problems, the present inventors have determined that the free volume radius of the polymer constituting the pattern-forming composition and the pattern-forming film formed from the pattern-forming composition It has been found that by making the nuclear radius of the introduced metal satisfy a predetermined condition, etching processability when forming a pattern on a substrate can be improved.
Specifically, the present invention has the following configuration.

一般式（１０３）及び（１０４）中、Ｒ^１はそれぞれ独立に水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子、アルキル基、アシル基、アリール基、トリメチルシリル基又はホスホリル基を表し、複数あるＲ^１は同一であっても異なっていてもよい；Ｒ^５は水素原子又はアルキル基を表す；Ｘ^１及びＹ^１はそれぞれ独立に単結合又は連結基を表す；ｒは１以上の整数を表し、＊印はｒが２以上の場合にＲ^１のいずれか１つとの結合部位を表すか、もしくはＲ^１に代わってＲ^１が結合している酸素原子のいずれか１つとの結合部位を表す。
［４］ ポリマーは、下記一般式（１０５）で表される構造をさらに有する、［１］～［３］のいずれかに記載のパターン形成用組成物；

一般式（１０５）中、Ｗ^１は炭素原子又はケイ素原子を表し、Ｗ^２は、－ＣＲ_２－、－Ｏ－、－Ｓ－又は－ＳｉＲ_２－を表す（但し、Ｒは水素原子又は炭素数が１～５のアルキル基を表し、複数あるＲは同一であっても異なっていてもよい）；Ｒ^１１は水素原子、炭素数が１以上３以下のアルキル基又は水酸基を表し、Ｒ^１２は水素原子、水酸基、アセチル基、メトキシカルボニル基、アリール基、アリル基、グリシジルエーテル基、グリシジルエステル基、イソシアネートエステル基又はピリジル基を表す。
［５］ ポリマーは、糖誘導体に由来する単位を含み、ポリマーにおける糖誘導体に由来する単位の含有率は６０～９０質量％である、［１］～［４］のいずれかに記載のパターン形成用組成物。
［６］ パターン形成用マスク材料である、［１］～［５］のいずれかに記載のパターン形成用組成物。
［７］ ポリマーを含むパターン形成用組成物を基板上に塗布し、パターン形成用膜を形成する工程と、
パターン形成用膜の少なくとも一部に金属を導入する工程と、を含むパターン形成方法であって、
ポリマーの自由体積半径をＰｒとし、
金属の原子核半径をＭｒとした場合、
２≦Ｐｒ／Ｍｒ≦３．３の条件を満たす、パターン形成方法。
［８］ パターン形成用膜を形成する工程の後に、パターン形成用膜にパターンを形成する工程をさらに含む、［７］に記載のパターン形成方法。
［９］ 金属を導入する工程の後に、エッチング工程をさらに含む、［７］又は［８］に記載のパターン形成方法。 [1] A pattern-forming composition containing a polymer,
Let the free volume radius of the polymer be Pr,
When the nuclear radius of the metal introduced when forming a pattern from the pattern forming composition is Mr,
A pattern forming composition that satisfies the condition of 2≦Pr/Mr≦3.3.
[2] The pattern-forming composition according to [1], wherein the polymer includes units derived from a sugar derivative.
[3] The pattern according to [2], wherein the unit derived from a sugar derivative includes at least one selected from a structure represented by the following general formula (103) and a structure represented by the following general formula (104). Forming composition;

In general formulas (103) and (104), R ¹ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group; Certain R ¹ may be the same or different; R ⁵ represents a hydrogen atom or an alkyl group; X ¹ and Y ¹ each independently represent a single bond or a connecting group; r represents an integer of 1 or more; When r is 2 or more, the mark * represents the bonding site with any one of ^R1 , or the bonding site with any one of the oxygen atoms to which ^R1 is bonded instead of ^R1 . represent.
[4] The pattern forming composition according to any one of [1] to [3], wherein the polymer further has a structure represented by the following general formula (105);

In general formula (105), W ¹ represents a carbon atom or a silicon atom, and W ² represents -CR ₂ -, -O-, -S- or -SiR ₂ - (provided that R is a hydrogen atom or a carbon R represents a hydrogen atom, an alkyl group having 1 to ³ carbon atoms, or a hydroxyl group; R ¹² represents an alkyl group having 1 to 5 carbon atoms; represents a hydrogen atom, a hydroxyl group, an acetyl group, a methoxycarbonyl group, an aryl group, an allyl group, a glycidyl ether group, a glycidyl ester group, an isocyanate ester group, or a pyridyl group.
[5] The pattern formation according to any one of [1] to [4], wherein the polymer includes units derived from a sugar derivative, and the content of the units derived from the sugar derivative in the polymer is 60 to 90% by mass. Composition for use.
[6] The pattern forming composition according to any one of [1] to [5], which is a pattern forming mask material.
[7] A step of applying a pattern-forming composition containing a polymer onto a substrate to form a pattern-forming film;
A pattern forming method comprising the step of introducing metal into at least a portion of a pattern forming film,
Let the free volume radius of the polymer be Pr,
When the nuclear radius of metal is Mr,
A pattern forming method that satisfies the condition 2≦Pr/Mr≦3.3.
[8] The pattern forming method according to [7], further comprising a step of forming a pattern on the pattern forming film after the step of forming the pattern forming film.
[9] The pattern forming method according to [7] or [8], further comprising an etching step after the step of introducing metal.

According to the present invention, it is possible to improve etching processability when processing a pattern shape on a substrate after forming a pattern forming film from a pattern forming composition.

FIG. 1 is a schematic diagram illustrating a process of forming a pattern on a substrate.

In the following, the present invention will be explained in detail. Although the constituent elements described below may be explained based on typical embodiments and specific examples, the present invention is not limited to such embodiments. Note that in this specification, substituents that are not specified as substituted or unsubstituted are meant to have the meaning that they may have any substituent.

(Pattern forming composition)
The present invention relates to pattern-forming compositions containing polymers. A metal is introduced into the pattern forming film formed from the pattern forming composition of the present invention, and at this time, the atomic nucleus radius of the metal introduced into the pattern forming film is Mr, When the free volume radius of the polymer contained in the composition is Pr, the condition of 2≦Pr/Mr≦3.3 is satisfied. As described above, the present invention relates to a pattern forming composition containing a polymer having a free volume radius (Pr) that satisfies the above conditions with respect to the nuclear radius (Mr) of the introduced metal in the pattern forming step. It is something.

Here, the nuclear radius (Mr) of the metal introduced into the pattern forming film is determined by E Clementi, D L Raimondi, W P Reinhardt (1963) J Chem Phys. 38:2686. Note that even when the metal introduced into the pattern forming film is a metal oxide such as Al ₂ O ₃ , it is sufficient that the nuclear radius of the metal element (Al) satisfies the above conditions.

Moreover, the free volume radius (Pr) of the polymer is a value measured as follows. First, a polymer solution sample is obtained by dissolving the polymer in PGMEA at a concentration of 3% by mass and 0.3% by mass of p-toluenesulfonic acid. The polymer solution sample is then spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 500 nm, it is baked on a hot plate at 230° C. for 5 minutes to form a pattern forming film. Next, the free volume radius (Pr) of the polymer is calculated by measuring the positron annihilation lifetime of the formed pattern forming film. Specifically, the pattern-forming film is placed in a positron annihilation lifetime measuring device. Using a 22Na-based positron beam as a positron beam source and a BaF ₂ scintillator and a photomultiplier tube as a γ-ray detector, the positron annihilation lifetime is measured under the following conditions. As the positron annihilation lifetime measuring device, for example, a small positron beam generator PALS-200A manufactured by Fuji Invac can be used.
Device constants: 263-272ps, 24.55ps/ch
Beam intensity: 1.5keV
Measurement depth: 0-25μm (estimated)
Measurement temperature: Room temperature Measurement atmosphere: Vacuum Total number of counts: Approximately 5,000,000 counts Sample pretreatment: Vacuum degassing at room temperature The positron annihilation lifetime curve obtained above was analyzed using the nonlinear least squares program POSITRONFIT, and the mean free volume radius was calculated. , the free volume radius of the polymer (Pr).

The preferred free volume radius (Pr) of the polymer varies depending on the nuclear radius of the metal introduced into the pattern forming film, but for example, the free volume radius (Pr) of the polymer is preferably 0.10 nm or more, and 0. The thickness is more preferably .20 nm or more, and even more preferably 0.25 nm or more. Further, the free volume radius (Pr) of the polymer is preferably 0.50 nm or less, more preferably 0.40 nm or less, and even more preferably 0.35 nm or less. In order to keep the free volume radius (Pr) of the polymer within the above range, for example, the content of units derived from sugar derivatives constituting the polymer may be adjusted, or the degree of polymerization of the sugar moiety and the length of the sugar chain may be adjusted. It is conceivable to adjust the content of other structural units other than the units derived from the sugar derivative as appropriate.

The value of Pr/Mr may be 2 or more, preferably 2.1 or more, more preferably 2.2 or more, even more preferably 2.3 or more, 2.4 or more. It is particularly preferable that Further, the value of Pr/Mr should just be 3.3 or less, preferably 3.2 or less, more preferably 3.1 or less, and even more preferably 3.0 or less. By setting the value of Pr/Mr within the above range, the permeability of metal into the pattern-forming film can be increased, thereby making it possible to form a high-strength pattern-forming film. Therefore, after forming a pattern-forming film from the pattern-forming composition, etching processability when processing a pattern shape on a substrate can be more effectively improved.

Here, the etching processability can be evaluated by calculating the etching selectivity, and the etching selectivity can be calculated as follows, for example. In order to calculate the etching selectivity ratio, first, a polymer solution sample is obtained by dissolving the polymer in PGMEA at 3% by mass and 0.3% by mass in p-toluenesulfonic acid. The polymer solution sample is then spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 300 nm, it is baked on a hot plate at 230° C. for 1 minute to form a pattern forming film. Next, it is masked in a line-and-space (line width 100 nm, space width 100 nm) shape using an ArF excimer laser exposure machine, and exposed using a commercially available ArF resist. Thereafter, the film is baked on a hot plate at 105° C. for 1 minute, and then immersed in a developer to form a line and space pattern. Next, this pattern sample is subjected to oxygen plasma treatment (100 sccm, 4 Pa, 100 W, 60 seconds) on the substrate using an ICP plasma etching device (manufactured by Tokyo Electron) to form a line and space pattern on the pattern forming film. do. Thereafter, this pattern-forming film was placed in ALD (atomic layer deposition apparatus: SUNALE R-100B manufactured by PICUSAN), and TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas was introduced for 300 seconds at 95°C. , water vapor is introduced for 150 seconds. By repeating this operation three times, Al ₂ O ₃ is introduced into the pattern forming film. Using this pattern as a mask, plasma treatment (100 sccm, 0.4 Pa, 200 W, 120 seconds) was performed using an ICP plasma etching device (manufactured by Tokyo Electron) using hexafluoroethane (C ₂ F ₆ ) and Ar gas to remove silicon. Perform dry etching of the oxide film. The patterned cross section of the silicon oxide film before and after plasma treatment was then observed using a scanning electron microscope (SEM) JSM7800F (manufactured by JEOL) at an acceleration voltage of 1.5 kV, an emission current of 37.0 μA, and a magnification of 100,000 times. Then, the thickness of the pattern forming film into which the metal was introduced and the depth of processing into the silicon oxide film portion were measured, and the etching selectivity was calculated using the following formula.
Etching selectivity = Processing depth to silicon oxide film / (Thickness of pattern forming film before plasma treatment - Thickness of pattern forming film after plasma treatment)
The etching selectivity ratio is preferably larger than 2.0, more preferably 2.5 or more, even more preferably 3.0 or more, even more preferably 5.0 or more, and 10.0 or more. It is particularly preferable that In this specification, when the etching selection ratio is within the above range, it can be determined that the etching processability when processing a pattern shape on a substrate is good. Note that when the etching processability is good, it is generally possible to dig deeply into the substrate.

In the present invention, the maximum metal content (atom%) when introducing metal into the pattern forming film is preferably 15 atom% or more, more preferably 20 atom% or more, and 25 atom% or more. It is even more preferable. Note that the maximum metal content (atom %) when metal is introduced into the pattern forming film is calculated as follows. First, a polymer solution sample is obtained by dissolving the polymer in PGMEA at a concentration of 3% by mass and 0.3% by mass of p-toluenesulfonic acid. The polymer solution sample is then spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 300 nm, it is baked on a hot plate at 230° C. for 5 minutes to form a pattern forming film. Next, the pattern forming film was placed in ALD (atomic layer deposition apparatus: SUNALE R-100B manufactured by PICUSAN), and after introducing TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas at 95° C. for 300 seconds, Introduce water vapor for 150 seconds. By repeating this operation three times, Al ₂ O ₃ is introduced into the pattern forming film. The pattern-forming film after introduction of Al ₂ O ₃ was installed in an XPS device (Nexsa XPS System manufactured by Thermo Fisher Scientific), and the concentration profile of Al element in the film thickness direction was determined by obtain. The thickness of the pattern-forming film after introducing Al ₂ O ₃ is determined by scratching the sample surface with tweezers to expose the silicon substrate surface to form a step, and measuring this step with a palpable step meter (stock company). Obtained by measuring with Kosaka Seisakusho Model Number: ET-4000). That is, the maximum metal content (atom %) is the metal content at the thickness where the most metal is contained in the thickness direction of the pattern forming film.

Metals introduced into the pattern forming film include Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, and Ge. , As, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt , Au, Hg, Tl, Pb, Bi, Po, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc. Among these, it is preferable to use Al, B, Si, Sn, Te, Zr, and W as the metal introduced into the pattern forming film.

The pattern forming composition of the present invention is preferably a pattern forming mask material. That is, the pattern forming film formed from the pattern forming composition of the present invention preferably serves as a protective film when etching a substrate. The pattern-forming film formed from the pattern-forming composition of the present invention can also be expected to have an effect on the gas permeability required for nanoimprinting. Such a pattern forming film may be peeled off and removed after the etching process.

Moreover, the pattern-forming composition of the present invention may be a pattern-forming self-assembled composition. The term "directed self-assembly" as used herein refers to a phenomenon in which an organization or structure is spontaneously constructed, not due solely to control from external factors. For example, by applying a self-assembled composition for pattern formation onto a substrate and performing annealing etc., a film having a phase separation structure due to self-assembly (self-assembled film) is formed, and in this self-assembled film, By removing some of the phase, a pattern can be formed on the substrate. Such a pattern shape serves as a protective film, and it becomes possible to perform a desired etching process on the substrate.

(polymer)
The pattern-forming composition of the present invention preferably contains a polymer, and the polymer preferably contains units derived from a sugar derivative. The sugar derivative may be a sugar derivative derived from a monosaccharide, or may have a structure in which a plurality of sugar derivatives derived from a monosaccharide are bonded. In addition, in a polymer containing a unit derived from a sugar derivative, the unit derived from a sugar derivative may be a constitutional unit having a sugar derivative-derived structure in the side chain, or a constitutional unit having a sugar derivative-derived structure in the main chain. There may be.

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

Among these, the unit derived from the sugar derivative preferably contains at least one selected from the structure represented by the following general formula (103) and the structure represented by the following general formula (104).

In general formulas (103) and (104), R ¹ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group; Certain R ¹ may be the same or different. R ⁵ represents a hydrogen atom or an alkyl group. X ¹ and Y ¹ each independently represent a single bond or a connecting group. r represents an integer of 1 or more, and the mark * represents a bonding site with any one of R ¹ when r is 2 or more, or any oxygen atom to which R ¹ is bonded in place of R ¹ represents a binding site with one of

In general formulas (103) and (104), R ¹ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group, a trimethylsilyl group, or a phosphoryl group, A plurality of R ¹ 's may be the same or different. Among these, R ¹ is preferably each independently a hydrogen atom or an acyl group having 1 or more and 3 or less carbon atoms. Note that the above alkyl group also includes a sugar chain. That is, the sugar chain moieties in general formulas (103) and (104) may further have a branched chain.

When R ¹ is an alkyl group or an acyl group, the number of carbon atoms thereof can be appropriately selected depending on the purpose. For example, the number of carbon atoms is preferably 2 or more, preferably 200 or less, more preferably 100 or less, even more preferably 20 or less, and particularly preferably 4 or less.

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

In general formulas (103) and (104), R ⁵ represents a hydrogen atom or an alkyl group. Among these, R ⁵ is preferably a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

In general formulas (103) and (104), X ¹ and Y ¹ each independently represent a single bond or a linking group.
When X ¹ is a linking group, examples of X ¹ include groups containing an alkylene group, -O-, -NH ₂ -, carbonyl group, etc., but X ¹ is a single bond or has a carbon number of It is preferably an alkylene group having 1 or more and 6 or less carbon atoms, and more preferably an alkylene group having 1 or more and 3 or less carbon atoms.
When Y ¹ is a linking group, examples of Y ¹ include groups containing an alkylene group, a phenylene group, -O-, -C(=O)O-, and the like. Y ¹ may be a linking group that is a combination of these groups. Among these, Y ¹ is preferably a linking group represented by the following structural formula.

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

In general formulas (103) and (104), r represents an integer of 1 or more, may be 2 or more, or may be 3 or more. Further, r is preferably 1500 or less, more preferably 1200 or less, even more preferably 500 or less, even more preferably 100 or less, particularly preferably 50 or less, Most preferably it is 10 or less.

The average degree of polymerization of the sugar units is the same as the preferred range of r above. The average degree of polymerization of sugar units is the number of sugar units forming one sugar moiety, and if the sugar moiety has a side chain structure, the number of sugar units constituting the side chain is also included in the average degree of polymerization. It will be done. The average degree of polymerization of the sugar units described above can be calculated by the following measuring method.
First, a solution containing a sugar derivative is kept at 50° C. and centrifuged at 15,000 rpm for 15 minutes to remove insoluble matter. Thereafter, the total sugar content and reducing sugar content (both converted to xylose) of the supernatant are measured. The average degree of polymerization is then calculated by dividing the total amount of sugar by the amount of reducing sugar. If the above measurement method cannot be used, gel permeation chromatography, size exclusion chromatography, light scattering method, viscosity method, end group quantitative method, sedimentation velocity method, MULDI-TOF-MS method, structural analysis method by NMR, etc. may be adopted.
When measuring the average degree of polymerization of sugar units after copolymer synthesis, the integrated value of the peak derived from the sugar chain (around 3.3-5.5 ppm) and the peak derived from other components of the sugar derivative in ¹ H-NMR are used. The integral value is calculated, and the average degree of polymerization is calculated from the ratio of each integral value. In addition, when R ¹ in general formulas (103) and (104) is not a hydrogen atom, the integral value of the peak derived from -OR ¹ group can be used instead of the peak derived from the sugar chain (however, in this case, R ¹ of the -OR ¹ group is not a sugar chain).

The * mark in general formulas (103) and (104) represents a bonding site with any one of R ¹ when r is 2 or more, or an oxygen atom to which R ¹ is bonded in place of R ¹ represents a binding site with any one of the following. That is, the polymerization site of the sugar unit in general formulas (103) and (104) may be either R ¹ in the sugar unit or the oxygen atom to which R ¹ is bonded, and either one is the polymerization site. It is preferable that Note that when R ¹ is an alkyl group having a substituent, R ¹ may be a sugar chain, so the number of bonding sites marked with * in general formulas (103) and (104) is one. However, in reality, a sugar chain may have a side chain consisting of an additional sugar chain.

The unit derived from the sugar derivative contains at least one selected from the structure represented by the above general formula (103) and the structure represented by the above general formula (104), but the unit derived from the above general formula (103) It is preferable that the structure mainly contains the following structure. This is thought to be because the structure represented by the above general formula (103) is more compact than the structure represented by the above general formula (104), making it easier to control the free volume radius of the polymer.

The polymer contained in the pattern-forming composition of the present invention is preferably a copolymer. The copolymer may be a block copolymer, but is preferably a random copolymer. By using a random copolymer, a more homogeneous pattern-forming film can be formed.

When the polymer contained in the pattern-forming composition is a copolymer, the polymer preferably further has a structure represented by the following general formula (105).

In general formula (105), W ¹ represents a carbon atom or a silicon atom. Among these, W ¹ is preferably a carbon atom. In general formula (105), W ² represents -CR ₂ -, -O-, -S- or -SiR ₂ - (provided that R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms). and multiple R's may be the same or different). Among these, W ² is preferably -CR ₂ -, more preferably -CH ₂ -.

In general formula (105), R ¹¹ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a hydroxyl group. The alkyl group having 1 to 3 carbon atoms is preferably a methyl group, R ¹¹ is more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

In general formula (105), R ¹² represents a hydrogen atom, a hydroxyl group, an acetyl group, a methoxycarbonyl group, an aryl group, an allyl group, a glycidyl ether group, a glycidyl ester group, an isocyanate ester group, or a pyridyl group. The allyl group is preferably a group represented by -R ₃ -CH=CH ₂ , the glycidyl ether group is preferably a group represented by -CH ₂ O-R ₃ -epoxy, and the glycidyl ether group is preferably a group represented by -CH 2 O-R 3 -epoxy. The group is preferably a group represented by -COO-R ₃ -epoxy, and the isocyanate ester group is preferably a group represented by -COO-R ₃ -NCO. Here, R ₃ is an alkylene group which may have a substituent. Examples of the alkylene group which may have a substituent include -CH ₂ -, -(CH ₂ ) ₂ -, -(CH ₂ ) ₃ -, -(CH ₂ ) ₄ -, -(CH ₂ ) ₅ -, -CH ₂ OCH ₂ -, -(CH ₂ ) ₂ OCH ₂ -, -(CH ₂ ) ₃ OCH ₂ -, -(CH ₂ ) ₄ OCH ₂ -, -(CH ₂ ) ₅ OCH ₂ -, etc. can be mentioned. Further, the alkylene group which may have a substituent may be a cycloalkylene group or a bridged cyclic cycloalkylene group.

Among these, ^R12 is preferably a methoxycarbonyl group, an aryl group, a glycidyl ether group, a glycidyl ester group, or a pyridyl group, more preferably a glycidyl ester group or an aryl group, and a glycidyl ester group or a phenyl group. is even more preferable. Moreover, it is also preferable that the phenyl group is a phenyl group having a substituent. Examples of the phenyl group having a substituent include 4-t-butylphenyl group, methoxyphenyl group, dimethoxyphenyl group, trimethoxyphenyl group, trimethylsilylphenyl group, and tetramethyldisilylphenyl group. Further, it is also preferable that R ¹² is a naphthalene group.

As mentioned above, R ¹² is preferably a phenyl group, and in this case, the unit derived from the structure represented by general formula (105) is a unit derived from a styrene compound. Examples of styrene compounds include styrene, o-methylstyrene, p-methylstyrene, ethylstyrene, p-methoxystyrene, p-phenylstyrene, 2,4-dimethylstyrene, pn-octylstyrene, pn- Examples include decylstyrene, pn-dodecylstyrene, chlorostyrene, bromostyrene, trimethylsilylstyrene, hydroxystyrene, 3,4,5-methoxystyrene, pentamethyldisilystyrene, and the like. Among these, the styrene compound is preferably at least one selected from styrene and trimethylsilylstyrene, and more preferably styrene.

Further, it is also preferable that R ¹² is a glycidyl ester group. In this case, the unit derived from the structure represented by general formula (105) is a unit derived from a glycidyl acrylate compound. Examples of the glycidyl acrylate compound include glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, oxiran-2-ylmethyl-2-ethylidene pentanoate, and the like. Among these, the glycidyl acrylate compound is preferably at least one selected from glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether.

The weight average molecular weight (Mw) of the polymer is preferably 500 or more, more preferably 1000 or more, and even more preferably 1500 or more. Further, the weight average molecular weight (Mw) of the polymer is preferably 1 million or less, more preferably 500,000 or less, even more preferably 300,000 or less, and even more preferably 250,000 or less. . Note that the weight average molecular weight (Mw) of the polymer is a value measured in terms of polystyrene by GPC.

The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polymer is preferably 1 or more. Further, Mw/Mn is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.3 or less. By setting Mw/Mn within the above range, the pattern forming composition of the present invention can form a fine and good pattern structure with higher accuracy.

As described above, the polymer contains units derived from sugar derivatives, and the content of units derived from sugar derivatives in the polymer is preferably 60% by mass or more, more preferably 70% by mass or more. Furthermore, the content of units derived from sugar derivatives in the polymer is preferably 90% by mass or less, more preferably 85% by mass or less. By controlling the content of units derived from sugar derivatives in the polymer within the above range, the solubility in organic solvents can be increased.

Further, the content of the unit represented by general formula (105) in the polymer may be 5% by mass or more, or 10% by mass or more with respect to the total mass of the polymer. Further, the content of units represented by general formula (105) in the polymer is preferably 40% by mass or less, more preferably 30% by mass or less. Note that the content of units represented by general formula (105) in the polymer can be calculated by ¹ H-NMR.

In addition, the polymer may have other structural units in addition to the above-mentioned structural units. Other structural units include, for example, lactic acid-derived units, siloxane bond-containing units, amide bond-containing units, urea bond-containing units, and the like.

(Polymer synthesis method)
The polymer can be synthesized by known polymerization methods such as living radical polymerization, living anion polymerization, and atom transfer radical polymerization. For example, in the case of living radical polymerization, a polymer can be obtained by reacting with a monomer using a polymerization initiator such as AIBN (α,α'-azobisisobutyronitrile). In the case of living anionic polymerization, polymers can be obtained by reacting butyllithium with monomers in the presence of lithium chloride.

The sugar moieties in the sugar derivatives described above may be obtained by synthesis, but may also be obtained by a combination of extraction steps from lignocellulose derived from woody plants or herbaceous plants. When employing a method of extracting from lignocellulose derived from woody plants or herbaceous plants to obtain sugar moieties, the extraction method described in JP-A-2012-100546 and the like can be used. Xylan can be extracted, for example, by the method disclosed in JP-A-2012-180424. Furthermore, cellulose can be extracted, for example, by the method disclosed in JP-A-2014-148629.

When obtaining a sugar derivative, it is preferable to modify the OH group of the sugar moiety using the above extraction method by acetylation, halogenation, or the like. For example, when introducing an acetyl group, an acetylated sugar derivative can be obtained by reacting with acetic anhydride.

The compound having the structure represented by general formula (105) may be formed by synthesis, or a commercially available product may be used. When synthesizing a compound having the structure represented by general formula (105), a known synthesis method can be employed. In addition, when using commercially available products, for example, Amino-terminated PS (Mw=12300Da, Mw/Mn=1.02, manufactured by Polymer Source Co., Ltd.), allyl glycidyl ether (manufactured by Tokyo Kasei Kogyo Co., Ltd.), glycidyl acrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), etc. (manufactured by Kogyo Co., Ltd.), glycidyl methacrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 4-hydroxybutyl acrylate glycidyl ether (manufactured by Mitsubishi Chemical Co., Ltd.), oxirane-2-ylmethyl-2-ethylidene pentanoate (manufactured by Achemica Co., Ltd.), 3,4 -Epoxycyclohexylmethyl methacrylate (manufactured by Daicel Corporation), etc. can be used.

Copolymers are described in Macromolecules Vol. 36, No. 6, 2003 for reference. Specifically, a sugar derivative and a compound having a structure represented by general formula (105) are placed in a solvent containing DMF, water, acetonitrile, etc., and a reducing agent is added. Examples of the reducing agent include NaCNBH ₃ and the like. Thereafter, the mixture is stirred at 30° C. or higher and 100° C. or lower for 1 day or more and 20 days or less, and a reducing agent is added as needed. A copolymer can be obtained by adding water to obtain a precipitate and vacuum drying the solid content.

In addition to the above-mentioned methods, methods for synthesizing the copolymer include methods using radical polymerization, RAFT polymerization, ATRP polymerization, click reaction, and NMP polymerization.
Radical polymerization is a polymerization reaction that occurs by adding an initiator and generating two free radicals through thermal or photoreaction. Monomers (e.g., styrene monomers and sugar methacrylate compounds with methacrylic acid added to the terminal β-1 position of xylooligosaccharides) and initiators (e.g., azo compounds such as azobisbutyronitrile (AIBN)) are heated at 150°C. In this way, a polystyrene-polysaccharide methacrylate random copolymer can be synthesized.
RAFT polymerization is a radical-initiated polymerization reaction that involves an exchange chain reaction utilizing thiocarbonylthio groups. For example, a method can be used in which the OH group attached to the terminal 1-position of xylooligosaccharide is converted into a thiocarbonylthio group, and then a styrene monomer is reacted at a temperature of 30°C to 100°C to synthesize a copolymer (Material Matters vol. .5, No. 1 Latest Polymer Synthesis Sigma-Aldrich Japan Co., Ltd.).
ATRP polymerization halogenates the terminal OH groups of sugars and forms metal complexes [(CuCl, CuCl ₂ , CuBr, CuBr ₂ or CuI, etc.) + TPMA (tris(2-pyridylmethyl)amine)], MeTREN (tris[2-(dimethylamino) )ethyl]amine), a monomer (e.g. styrene monomer), and a polymerization initiator (2,2,5-trimethyl-3-(1-phenylethoxy)-4-phenyl-3-azahexane). A sugar copolymer (eg, a sugar-styrene block copolymer) can be synthesized by.
In NMP polymerization, an alkoxyamine derivative is used as an initiator and heated to cause coupling and reaction with monomer molecules to produce nitroxide. Thereafter, the polymerization reaction progresses as radicals are generated by thermal dissociation. Such NMP polymerization is a type of living radical polymerization reaction. A monomer (for example, a styrene monomer and a sugar methacrylate compound with methacrylic acid added to the terminal β-1 position of a xylooligosaccharide) is mixed, and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) is used as an initiator. A polystyrene-polysaccharide methacrylate random copolymer can be synthesized by heating at 140°C.
The click reaction is a 1,3-dipolar azide/alkyne cycloaddition reaction using a sugar with a propargyl group and a Cu catalyst.

(Method for producing pattern-forming composition)
In the method for producing a pattern-forming composition, it is preferable to mix the above-mentioned polymer and a solvent. The solvent is preferably an organic solvent, and examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, sulfur-containing solvents, amide solvents, ester solvents, and hydrocarbon solvents. It will be done. These solvents may be used alone or in combination of two or more.

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

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

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

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

Examples of the sulfur-containing solvent include dimethyl sulfoxide.

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

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

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

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

The content of the polymer in the pattern-forming composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, based on the total mass of the pattern-forming composition. Further, the content of the polymer is preferably 30% by mass or less based on the total mass of the pattern-forming composition.

<Optional ingredients>
When producing a pattern-forming composition, an ionic liquid may be further added as an optional component. An ionic liquid is a solvent that is liquid at 100° C. or lower and is composed only of ions. In the ions constituting the ionic liquid, at least one of a cation part and an anion part is composed of an organic ion.

When the pattern forming composition contains an ionic liquid, the compatibility between the polymer and the organic solvent can be improved. The ionic liquid also has the function of promoting phase separation of the block copolymer.

An ionic liquid consists of a cation part and an anion part, and the cation part of an ionic liquid is not particularly limited, and those commonly used for the cation part of ionic liquids can be used. Preferred examples of the cation moiety of the ionic liquid include nitrogen-containing aromatic ions, ammonium ions, and phosphonium ions.

Examples of nitrogen-containing aromatic cations include pyridinium ion, pyridazinium ion, pyrimidinium ion, pyrazinium ion, imidazolium ion, pyrazonium ion, oxazolium ion, 1,2,3-triazolium ion, 1, Examples include 2,4-triazolium ion, thiazolium ion, piperidinium ion, and pyrrolidinium ion.

Examples of the anion moiety of the ionic liquid include a halogen ion, a carboxylate ion, a phosphinate ion, a phosphate ion, a phosphonate ion, a bis(trifluoromethylsulfonyl)imide ion, and a bis(trifluoromethylsulfonyl)imide ion is preferred. Examples of the halogen ion include chloride ion, bromide ion, and iodide ion, with chloride ion being preferred. Examples of carboxylate ions include formate ion, acetate ion, propionate ion, butyrate ion, hexanoate ion, maleate ion, fumarate ion, oxalate ion, rectate ion, pyruvate ion, etc. , formate ion, acetate ion, and propionate ion are preferred.

The pattern forming composition may contain, for example, a surfactant or the like as an optional component. When the pattern-forming composition contains a surfactant, it is possible to improve the applicability of the pattern-forming composition to a substrate or the like. Preferred surfactants include nonionic surfactants, fluorine surfactants, and silicone surfactants. These may be used alone or in combination of two or more.

Moreover, the pattern-forming composition may further contain a catalyst as an optional component. Examples of the catalyst include acid compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, ammonium dodecylbenzenesulfonate, and hydroxybenzoic acid. Examples of the curing agent include ethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, dimethylaminopropylamine, m-xylenediamine, m-phenylenediamine, triethylamine, and benzyldimethylamine.

The pattern-forming composition of the present invention may contain a monomer component constituting a polymer. For example, various monomers constituting the polymer can be added as appropriate to improve desired properties.

(Pattern formation method)
The present invention provides a pattern-forming composition comprising the steps of: applying a pattern-forming composition containing the above-mentioned polymer onto a substrate to form a pattern-forming film; and introducing a metal into at least a portion of the pattern-forming film. It also concerns the formation method. Here, when the free volume radius of the polymer is Pr and the nuclear radius of the metal is Mr, the condition of 2≦Pr/Mr≦3.3 is satisfied. According to the pattern forming method of the present invention, it is possible to improve etching processability when processing a pattern shape on a substrate after forming a pattern forming film from a pattern forming composition.

Examples of the substrate used in the pattern forming method of the present invention include substrates made of glass, silicon, SiN, GaN, AlN, and the like. Further, a substrate made of an organic material such as PET, PE, PEO, PS, cycloolefin polymer, polylactic acid, or cellulose nanofiber may also be used. Further, a plurality of layers made of different materials may be sandwiched between the substrate and the guide pattern forming layer. This material is not particularly specified, but may include inorganic materials such as SiO ₂ , SiN, Al ₂ O ₃ , AlN, GaN, GaAs, W, SOC, and SOG, and commercially available adhesives. Examples include organic materials.

The method for forming a pattern-forming film by applying a pattern-forming composition onto a substrate is not particularly limited, but examples include a method of applying the pattern-forming composition to be used by a spin coating method or the like. It will be done.

The pattern forming method of the present invention preferably further includes a step of forming a pattern on the pattern forming film after the step of forming the pattern forming film. In the process of forming a pattern, first, as shown in FIG. 1(a), a pattern forming film 20 is formed by applying a pattern forming composition onto a substrate 10. Then, as shown in FIG. 1B, at least a portion of the pattern forming film 20 is removed so as to form a pattern desired to be formed on the substrate 10. For example, by stacking a resist film on the pattern forming film 20 and performing exposure and development processing, a pattern shape as shown in FIG. 1(b) can be formed.

Examples of methods for removing a part of the pattern forming film include reactive ion etching (RIE) such as chemical dry etching and chemical wet etching (wet development), and physical etching such as sputter etching and ion beam etching. Known methods may be used. The pattern forming film can be removed using, for example, tetrafluoromethane, perfluorocyclobutane (C ₄ F ₈ ), perfluoropropane (C ₃ F ₈ ), perfluoroethane (C ₂ F ₆ ), boron trichloride, or trifluoride. This can be done by dry etching using gases such as methane, trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, chlorine, helium, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, and chlorine trifluoride. preferable.

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

A pattern can be formed on the pattern forming film as described above. The pattern to be formed is preferably a line and space pattern, a hole pattern, or a pillar pattern.

The pattern forming method of the present invention includes the step of introducing metal into at least a portion of the pattern forming film. Although the step of introducing metal is preferably provided after the pattern shape is formed on the pattern forming film, the metal introducing step may be provided before the pattern shape is formed on the pattern forming film. The metals introduced into the pattern forming film include Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Examples include Pt, Au, Hg, Tl, Pb, Bi, Po, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The step of introducing metal into the pattern forming film can be performed, for example, by the method described in Journal of Photopolymer Science and Technology Volume 29, Number 5 (2016) 653-657. In addition, when introducing metal into the pattern forming film, it is possible to adopt a method using a metal complex gas, a method of applying a solution containing metal, or a method of introducing metal into the resist using an ion implant method. can.

It is preferable that an etching step is further provided after the step of introducing metal into at least a portion of the pattern forming film. This etching step is a step in which the substrate is etched using the patterned pattern forming film as a protective film (mask), as shown in FIG. 1(c).

Methods for processing the substrate in the etching process include known methods such as reactive ion etching (RIE) such as chemical dry etching and chemical wet etching (wet development), and physical etching such as sputter etching and ion beam etching. can be mentioned. The substrate can be processed using, for example, tetrafluoromethane, perfluorocyclobutane (C ₄ F ₈ ), perfluoropropane (C ₃ F ₈ ), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, chlorine, sulfur hexafluoride. It is preferable to perform dry etching using a gas such as , difluoromethane, nitrogen trifluoride, or chlorine trifluoride.

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

EXAMPLES The features of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

(Example 1)
[Synthesis of copolymer 1]
(Synthesis of acetyl sugar methacrylate 1)
20 g of xylose was added to a mixed solution of 250 g of acetic anhydride and 320 g of acetic acid, and the mixture was stirred at 30° C. for 2 hours. Approximately 5 times the amount of cold water as the solution was slowly added while stirring, stirred for 2 hours, and then left to stand overnight. 10 g of precipitated crystals were added to a solution of 1.2 g of ethylenediamine and 01.4 g of acetic acid added to 400 mL of THF and heated to 0° C. and stirred for 4 hours. This was poured into 1 L of cold water and extracted twice with dichloromethane. 20 g of this extract, 300 mL of dichloromethane, and 4.8 g of triethylamine were placed in a flask and cooled to -30°C. 2.8 g of methacryloyl chloride was added and stirred for 2 hours. This was poured into 300 mL of cold water, extracted twice with dichloromethane, and the solvent was concentrated to obtain 16.1 g of acetyl xylose methacrylate 1. The structure of the obtained acetyl xylose methacrylate 1 is as follows.

(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate random copolymer)
In a flask were placed 12.0 g of acetyl sugar methacrylate, 2.6 g of styrene (manufactured by Tokyo Kasei Co., Ltd.), 2.6 g of glycidyl methacrylate (manufactured by Tokyo Kasei Co., Ltd.), 100 g of THF as a solvent, and 0.8 g of azobisisobutyronitrile as a polymerization initiator. After charging, the glass container was sealed, the temperature was raised to 78° C. under a nitrogen atmosphere, and the mixture was stirred for 6.0 hours. Thereafter, the temperature was returned to room temperature, the inside of the glass container was placed under the atmosphere, and 300 g of methanol was added dropwise to the resulting solution to precipitate a polymer. Thereafter, the solution containing the precipitated polymer was suction-filtered to obtain 112 g of white copolymer 1. The obtained copolymer 1 contains the following structural units.

[Preparation of solution sample]
Copolymer 1 was dissolved in PGMEA to give 3% by mass and p-toluenesulfonic acid as a polymerization catalyst 0.3% by mass to obtain a polymer solution sample.

(Example 2)
[Synthesis of copolymer 2]
(Synthesis of acetyl xylose methacrylate-styrene-glycidyl methacrylate random copolymer)
Copolymer 1 was synthesized in the same manner as in Example 1, except that the amount of styrene added was changed from 2.6 g to 2.3 g, and the amount of glycidyl methacrylate added was changed from 2.6 g to 0.8 g. 12.0 g of Copolymer 2 was obtained. Further, a polymer solution sample was obtained in the same manner as in Example 1.

(Example 3)
[Synthesis of copolymer 3]
(Synthesis of acetyl xylose methacrylate-styrene random copolymer)
In the synthesis of Copolymer 1, 12.0 g of Copolymer 3 was obtained in the same manner as in Example 1, except that the amount of styrene added was changed from 2.6 g to 2.1 g, and glycidyl methacrylate was not added. Further, a polymer solution sample was obtained in the same manner as in Example 1.

(Example 4)
[Synthesis of copolymer 4]
(Synthesis of acetyl xylotriose methacrylate-styrene random copolymer)
12.1 g of Copolymer 4 was obtained in the same manner as in Example 1 except that xylose was changed to xylotriose in the synthesis of Copolymer 1. Further, a polymer solution sample was obtained in the same manner as in Example 1. The obtained copolymer 4 contains the following structural units.

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

[Evaluation of free volume radius]
The resulting polymer solution sample was spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 500 nm, it was baked on a hot plate at 230° C. for 5 minutes to form a pattern forming film.
The pattern-forming film thus formed was further cut into a 15 mm x 15 mm square and placed in a small positron beam generator PALS-200A (thin film compatible positron annihilation life measuring device) manufactured by Fuji Invac. Using a 22Na-based positron beam as a positron beam source and a BaF ₂ scintillator and a photomultiplier tube as a γ-ray detector, the positron annihilation lifetime was measured under the following conditions.
Device constants: 263-272ps, 24.55ps/ch
Beam intensity: 1.5keV
Measurement depth: 0-25μm (estimated)
Measurement temperature: Room temperature Measurement atmosphere: Vacuum Total number of counts: Approximately 5,000,000 counts Sample pretreatment: Vacuum degassing at room temperature The positron annihilation lifetime curve obtained above was analyzed using the nonlinear least squares program POSITRONFIT, and the mean free volume radius was calculated. .

[Evaluation of maximum metal introduction rate]
The resulting polymer solution sample was spin coated onto a 2 inch silicon wafer substrate. After coating to a film thickness of 300 nm, it was baked on a hot plate at 230° C. for 5 minutes to form a pattern forming film.
The pattern forming film thus formed was placed in ALD (atomic layer deposition apparatus: SUNALE R-100B manufactured by PICUSAN), and TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas was applied at 95° C. for 300 seconds. After the introduction, water vapor was introduced for 150 seconds. By repeating this operation three times, Al ₂ O ₃ was introduced into the pattern forming film.
The pattern-forming film after introduction of Al ₂ O ₃ was installed in an XPS device (Nexsa XPS System manufactured by Thermo Fisher Scientific), and the concentration profile of Al element in the film thickness direction was determined by Obtained. The thickness of the pattern-forming film after introducing Al ₂ O ₃ is determined by scratching the sample surface with tweezers to expose the silicon substrate surface to form a step, and measuring this step with a palpable step meter (stock company). It was determined by measuring with a model number: ET-4000 (manufactured by Kosaka Seisakusho).

[Preparation of sample for etching selectivity measurement]
The obtained polymer solution sample was spin-coated onto a 2-inch silicon wafer substrate with a silicon oxide film (film thickness: 2 um). After coating to a film thickness of 300 nm, the film was baked at 230° C. for 1 minute on a hot plate to form a pattern forming film.
It was masked in a line-and-space (line width 100 nm, space width 100 nm) shape using an ArF excimer laser exposure machine, and exposure was performed using a commercially available ArF resist. Thereafter, the film was baked on a hot plate at 105° C. for 1 minute, and then immersed in a developer to form a line-and-space pattern.
Next, this pattern sample is subjected to oxygen plasma treatment (100 sccm, 4 Pa, 100 W, 60 seconds) on the substrate using an ICP plasma etching device (manufactured by Tokyo Electron) to remove the photoresist and turn it into a pattern forming film. A line and space pattern was formed. Thereafter, metal was introduced into the pattern forming film in the same manner as in the evaluation of the metal introduction rate of the copolymer. Using this pattern as a mask, plasma treatment (100 sccm, 0.4 Pa, 200 W, 120 seconds) was performed using an ICP plasma etching device (manufactured by Tokyo Electron) using hexafluoroethane (C ₂ F ₆ ) and Ar gas to remove silicon. The oxide film was dry etched.

[Evaluation of etching processability]
A patterned cross section of the silicon oxide film before and after plasma treatment using hexafluoroethane (C ₂ F ₆ ) and Ar gas was examined using a scanning electron microscope (SEM) JSM7800F (manufactured by JEOL Ltd.) at an accelerating voltage of 1. Observed at 5kV, emission current 37.0μA, and 100,000x magnification, the thickness of the pattern forming film into which the metal was introduced (thickness c in Figure 1(b) and thickness c' in Figure 1(c)) and , the depth of processing into the silicon oxide film portion (depth d in FIG. 1(c)) was measured. Then, the etching selectivity was calculated using the following formula.
Etching selectivity = Processing depth to silicon oxide film / (Thickness of pattern forming film before plasma treatment - Thickness of pattern forming film after plasma treatment)
Then, the etching processability was evaluated based on the following criteria.
◎: Etching selection ratio is 10 or more ○: Etching selection ratio is 2 or more and less than 10 ×: Etching selection ratio is less than 2

(Example 5)
Example 1 except that trimethyl borate (B(OCH ₃ ) ₃ ) gas was used instead of TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas when introducing metal into the pattern forming film in Example 1. Various evaluations were performed in the same manner as in 1.

(Example 6)
Example 1 except that when introducing metal into the pattern forming film in Example 1, trimethylantimony (Sb(CH ₃ ) ₃ ) gas was used instead of TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas. Various evaluations were conducted in the same manner.

(Comparative example 1)
Example 1 except that trimethylindium (In(CH ₃ ) ₃ ) gas was used instead of TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas when introducing metal into the pattern forming film in Example 1. Various evaluations were conducted in the same manner.

(Comparative example 2)
Example 1 except that trimethyl borate (B(OCH ₃ ) ₃ ) gas was used instead of TMA (trimethylaluminum, Al(CH ₃ ) ₃ ) gas when introducing metal into the pattern forming film in Example 1. Various evaluations were performed in the same manner as in 3.

In Table 1, the nuclear radius is determined by E Clementi, D L Raimondi, W P Reinhardt (1963) J Chem Phys. This value is based on the description of 38:2686.

In the example, since the condition of 2≦Pr/Mr≦3.3 was satisfied, the etching processability was good. On the other hand, the comparative example that did not satisfy the condition of 2≦Pr/Mr≦3.3 had poor etching processability.

10 Substrate 20 Pattern forming film

Claims (3)

a step of applying a pattern-forming composition containing a polymer onto a substrate to form a pattern-forming film;
A pattern forming method comprising the step of introducing metal into at least a portion of the pattern forming film,
The free volume radius of the polymer is Pr,
When the nuclear radius of the metal is Mr,
A pattern forming method that satisfies the condition 2≦Pr/Mr≦3.3. The pattern forming method according to claim 1 , further comprising the step of forming a pattern on the pattern forming film after the step of forming the pattern forming film. The pattern forming method according to claim 1 or 2 , further comprising an etching step after the step of introducing the metal.

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