Resist composition and pattern formation method

Abstract

To provide a resist composition which has high resolution and is excellent in roughness (LER, LWR), critical dimension uniformity (CDU) of a hole pattern, and etching resistance.SOLUTION: The resist composition contains: a resin (A) having units of general formulae (p-1), (a-1) and (b-1); a resin (B) having units of general formulae (p-2), (a-1) and (b-1); and a solvent (D). The content of the resin (A) is lower than the content of the resin (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resist composition and a method for forming a pattern using the resist composition. [Background technology]

[0002] With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. In particular, the expansion of the flash memory market and the increase in storage capacity are driving this miniaturization. As for the most advanced miniaturization technology, mass production of 65nm node devices using ArF lithography is underway, and preparations for mass production of the next generation 45nm node using ArF immersion lithography are underway. For the next generation 32nm node, candidates and ongoing investigations are underway, including immersion lithography using ultra-high NA lenses combining a liquid with a higher refractive index than water, a high refractive index lens, and a high refractive index material, extreme ultraviolet (EUV) lithography at a wavelength of 13.5nm, and double exposure (double patterning lithography) of ArF lithography.

[0003] To improve resolution and dimensional control at high energy beams, resist films tend to have low sensitivity. This decrease in resist film sensitivity leads to reduced productivity, which is undesirable. To meet the demand for higher sensitivity, chemically amplified resist materials are being investigated.

[0004] As miniaturization progresses, the edge roughness of line patterns (line edge roughness: LER and line width roughness: LWR) and the dimensional uniformity of hole patterns (critical dimension uniformity: CDU) are becoming a concern. The dissolution contrast of the base polymer in the developer, the uneven distribution and aggregation of acid generators, and the effects of acid diffusion have been pointed out as contributing factors. Furthermore, LER tends to increase as the resist film thins, and the deterioration of LER and etching resistance due to thinning as miniaturization progresses is becoming a serious problem.

[0005] Patent Document 1 discloses that in the formation of a positive-type fine line pattern, introducing a photoacid generator into the base polymer using an anionic monomer suppresses acid diffusion and improves resolution.

[0006] Patent Document 2 discloses that a photoacid generator is introduced into the polymer using a cationic agent, but this method fails to suppress acid diffusion, making it difficult to improve the LER (Low Acid Diffusion) mentioned above.

[0007] Patent Document 3 discloses that by using a polymer compound containing a photoacid generator that produces an alkanesulfonic acid with a fluorine atom substituted at the α position, and an acid generator that produces an alkanesulfonic acid without a fluorine atom substituted at the α position, the depth of focus, circularity, and LWR of hole patterns and trench patterns can be improved. This effect is due to the fact that alkanesulfonic acids with a fluorine substitution at the α position have higher acid strength than alkanesulfonic acids without fluorine substitution.

[0008] These prior art techniques are thought to work by having the strong acid generated from the photoacid generator upon exposure undergo salt exchange with the weak onium acid salt to form the strong onium acid salt. This replaces the highly acidic strong acid with a weak acid, suppressing the acid generation decomposition reaction of acid-unstable groups and reducing the acid diffusion distance. In other words, the weak onium acid salt is thought to function as a quencher (acid deactivator) for the strong acid generated by exposure. Compared to nitrogen-containing compounds such as amines, weak onium acid salts are generally non-volatile, which prevents changes in the concentration of the resist film surface during resist film formation and the baking process during patterning, thus improving the formation of rectangular patterns.

[0009] Patent Document 4 discloses that when onium alkanesulfonate is used, the acidity is not sufficiently low compared to onium carboxylate salts, resulting in low quenching ability and unsatisfactory resolution, edge roughness, and depth of field.

[0010] From the perspective of the trade-off between sensitivity and resolution, pattern formation in the high-exposure range is sometimes desired to further reduce resolution, LER, and CDU. In polymers in which anionic monomers are introduced as described above, the amount of decomposition products of the photoacid generator increases, and the resulting anions increase the solubility of the base polymer in alkaline developer compared to base polymers that do not contain photodegradable groups. If the solubility of the anionic portion of the polymer in alkaline developer due to exposure differs from the solubility due to the detachment of acid-unstable groups, there is a problem of reduced dissolution contrast. In addition, if the amount of acid diffusion inhibitor added to suppress acid diffusion increases, the solubility of the resist film in alkaline developer increases, and the dissolution contrast decreases. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2009-263487 [Patent Document 2] Special Publication No. 04-230645 [Patent Document 3] Japanese Patent Publication No. 2012-137518 [Patent Document 4] Japanese Patent Publication No. 2015-054833 [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention has been made in view of the above circumstances, and aims to provide a resist composition that reduces roughness (LER, LWR) and dimensional uniformity of hole patterns (CDU) with higher resolution than conventional resist materials even in high exposure ranges, and that has a good pattern shape after exposure and excellent etching resistance. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides: A resin (A) having a repeating unit represented by the following general formula (p-1), a repeating unit whose polarity changes by the action of an acid represented by the following general formula (a-1) and becomes soluble in an aqueous alkali solution, and a repeating unit represented by the following general formula (b-1), A resin (B) having a repeating unit represented by the following general formula (p-2), a repeating unit whose polarity changes by the action of an acid represented by the following general formula (a-1) and becomes soluble in an aqueous alkali solution, and a repeating unit represented by the following general formula (b-1), A solvent (D), A resist composition containing the above, Provided is a resist composition in which the content of the resin (A) contained in the resist composition is less than the content of the resin (B). [Chemical formula] (In general formula (p-1), R 1 is a hydrogen atom or a methyl group. Z 1 is a single bond, a phenylene group, -O-Z 11 -, -C(=O)-O-Z 11 -, -C(=O)-NH-Z 11 -, -Z 12 -Ph-, -Z 12 -O-Ph-, or -Z 12 -C(=O)-O-Ph-. Z 11 is an alkanediyl group having 1 to 6 carbon atoms or an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z 12 is a hydrocarbon group having 1 to 15 carbon atoms, and Ph is a phenylene group. R 2 ~R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, or a phenyl group. M 0- is a non-nucleophilic counter ion. In general formula (p-2), R 4 is a hydrogen atom or a methyl group. Z 2It is a single bond, a phenylene group, -OZ 21 -, -C(=O)-OZ 21 -, -Z 21 -C(=O)-O-, or -C(=O)-NH-Z 21 - is Z 21 This group consists of a single bond, an alkanediyl group having 1 to 20 carbon atoms, an alkenediyl group having 2 to 20 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. M 1+ This represents a substituted countercation, specifically a sulfonium cation, iodonium cation, or ammonium cation. R 5 This is either a hydrogen atom or a trifluoromethyl group. In general formula (a-1), R 6 This is a hydrogen atom or a methyl group. Y is a group whose polarity changes upon the action of an acid, making it soluble in alkaline aqueous solutions. In general formula (b-1), R 7 This is a hydrogen atom or a methyl group. Z 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, ester bonds, amide bonds, and -OZ. 31 -, -C(=O)-OZ 31 -or -C(=O)-NH-Z 31 - is Z 31 This is an alkanediyl group having 1 to 12 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond. n1 is an integer between 1 and 3, and n2 is an integer between 0 and 3, with the sum of n1 and n2 being 5 or less. R 8 (This refers to a halogen atom, or a linear hydrocarbon group having 1 to 10 carbon atoms, or a branched or cyclic hydrocarbon group having 3 to 10 carbon atoms, where the -CH2- atoms constituting these groups may be substituted with -O-, -C(=O)-O-, or -C(=O)-, or may be substituted with a hydrogen atom, a halogen atom, or a heteroatom.)

[0014] With such a resist composition, the ionic interaction between the anion-introduced base polymer and the cation-introduced base polymer forms a polymer composite with a large apparent molecular weight, resulting in a rigid film. Therefore, even in high exposure ranges, it is possible to suppress solubility of alkaline developers, reduce edge roughness (LER, LWR) and hole pattern dimensional uniformity (CDU) at high resolution, and provide a resist film with good post-exposure pattern shape and excellent etching resistance.

[0015] Furthermore, the resist composition of the present invention contains the non-nucleophilic counterion M in the general formula (p-1) above. 0- However, it is preferable that it be represented by the following general formula (e-0). [ka] (In general formula (e-0), R 8b , R 9 Each of these independently represents a hydrogen atom, a fluorine atom, or a trifluoromethyl group. R 10 (This represents a hydrogen atom, a hydroxyl group, a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted alkyl group having 6 to 30 carbon atoms.)

[0016] Such a resist composition can provide a resist composition that exhibits excellent rectangularity of the pattern after development and superior edge roughness.

[0017] Furthermore, it is preferable that the resist composition of the present invention contains resin (A) and resin (B) that do not contain repeating units having a lactone structure.

[0018] With such a resist composition, swelling can be suppressed by limiting the penetration of alkaline developer into the pattern, and a resist pattern with a more desirable shape can be obtained.

[0019] Furthermore, the resist composition of the present invention preferably further contains a resin (C), wherein the resin (C) does not contain repeating units whose polarity changes upon the action of an acid and which become soluble in an alkaline aqueous solution.

[0020] Such a resist composition can improve the uniformity of the film thickness across the wafer surface of a resist film coated by spin coating.

[0021] Furthermore, it is preferable that the resin (C) has repeating units represented by the following general formula (c-1). [ka] (In general formula (c-1), R 11 This is a hydrogen atom or a methyl group. X 1 This refers to a single bond or a divalent linking group, which is a divalent hydrocarbon group having 1 to 10 carbon atoms, a fluorinated phenylene group, or -OX. 11 -, -C(=O)-OX 11 -or -C(=O)-NH-X 11 - It is one of the following. 11 This is an alkanediyl group having 1 to 20 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond.

[0022] A resist composition containing a polymer having such a fluoroalcohol structure can improve the uniformity of the resist film coating and promote dissolution in an alkaline developer.

[0023] Furthermore, the resist composition of the present invention preferably further contains an onium salt (E) represented by the following general formula (e-1). [ka] (In general formula (e-1), R 12 ~R 13 Each of these independently represents a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 10 carbon atoms which may contain a fluorine atom, or a trifluoromethyl group. R 14 This represents a linear alkyl group having 1 to 20 carbon atoms, or a branched or cyclic alkyl group having 3 to 20 carbon atoms, which may contain hydrogen atoms, hydroxyl groups, ether bonds, and ester bonds, either substituted or unsubstituted, or an aryl group having 6 to 30 carbon atoms. M 2+ (This indicates a substituted countercation, representing a sulfonium cation or an iodonium cation.)

[0024] By adding such low molecular weight salts, the formation of polymer composites that allow for ionic interactions between the anion-introduced base polymer and the cation-introduced base polymer can be inhibited, thereby adjusting the apparent molecular weight.

[0025] Furthermore, the solvent (D) is preferably a mixed solvent selected from two or three of the following: propylene glycol monomethyl ether acetate, propylene glycol dimethyl ether, ethyl lactate, γ-butyrolactone, and 4-hydroxy-4-methyl-2-pentanone.

[0026] Using such solvents makes it possible to provide a resist composition with excellent coatability.

[0027] Furthermore, the present invention is A pattern formation method, (i) A step of forming a resist film on a substrate using the above resist composition, (ii) Exposing the resist film with a KrF excimer laser with a wavelength of 248 nm, an ArF excimer laser with a wavelength of 193 nm, EUV lithography with a wavelength of 13.5 nm, or an electron beam, (iii) A step of developing the exposed resist film with an alkaline developer, The present invention provides a pattern formation method that includes [specific details].

[0028] This pattern formation method allows for the formation of polymer composites, reducing edge roughness (LER, LWR) and hole pattern dimensional uniformity (CDU) at high resolution, and creating resist patterns with good post-exposure pattern shape and excellent etching resistance. [Effects of the Invention]

[0029] The resist composition of the present invention, considering the trade-off between sensitivity and resolution, maintains dissolution contrast by suppressing solubility in alkaline developers even in high exposure ranges where resolution is pursued, and even when using a base polymer into which an anion of a photoacid generator is introduced, exhibiting high resolution and good pattern shape and edge roughness after exposure. Therefore, a resist composition particularly suitable as a patterning material for ultra-large-scale integrated circuit (ULSI) manufacturing or EUV exposure can be obtained, especially a chemically amplified resist composition. [Modes for carrying out the invention]

[0030] As described above, in pursuit of high resolution, there was a need to develop a resist composition that could reduce edge roughness (LER, LWR) and dimensional uniformity of hole patterns (CDU) even with increased exposure, and that could form a resist pattern with a good pattern shape after exposure and excellent etching resistance.

[0031] As a result of diligent research to achieve the above objectives, we discovered that by using an anion-introduced base polymer and a cation-introduced base polymer, the ionic interaction between the polymers allows for the formation of a polymer composite with a large apparent molecular weight, thereby creating a rigid film. This suppresses solubility of alkaline developers even in high-exposure regions, reduces edge roughness (LER, LWR) and dimensional uniformity of hole patterns (CDU) at high resolution, and enables fine processing with good pattern shape. This led to the present invention.

[0032] In other words, the present invention is A resin (A) having repeating units represented by the following general formula (p-1), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), A resin (B) having repeating units represented by the following general formula (p-2), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), Solvent (D) and, A resist composition comprising, The resist composition is such that the content of resin (A) contained in the resist composition is less than the content of resin (B). [ka] (In general formula (p-1), R 1 This is a hydrogen atom or a methyl group. Z 1 It is a single bond, a phenylene group, -OZ 11 -, -C(=O)-OZ 11 -, -C(=O)-NH-Z 11 -, -Z 12 -Ph-, -Z 12 -O-Ph-, or -Z 12 -C(=O)-O-Ph- Z 11 This is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 12 is a hydrocarbon group with 1 to 15 carbon atoms, and Ph is a phenylene group. R 2 ~R 3 Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms, or a phenyl group. M 0- It is a non-nucleophilic counterion. In general formula (p-2), R 4 This is a hydrogen atom or a methyl group. Z 2It is a single bond, a phenylene group, -OZ 21 -, -C(=O)-OZ 21 -, -Z 21 -C(=O)-O-, or -C(=O)-NH-Z 21 - is Z 21 This group consists of a single bond, an alkanediyl group having 1 to 20 carbon atoms, an alkenediyl group having 2 to 20 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. M 1+ This represents a substituted countercation, specifically a sulfonium cation, iodonium cation, or ammonium cation. R 5 This is either a hydrogen atom or a trifluoromethyl group. In general formula (a-1), R 6 This is a hydrogen atom or a methyl group. Y is a group whose polarity changes upon the action of an acid, making it soluble in alkaline aqueous solutions. In general formula (b-1), R 7 This is a hydrogen atom or a methyl group. Z 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, ester bonds, amide bonds, and -OZ. 31 -, -C(=O)-OZ 31 -or -C(=O)-NH-Z 31 - is Z 31 This is an alkanediyl group having 1 to 12 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond. n1 is an integer between 1 and 3, and n2 is an integer between 0 and 3, with the sum of n1 and n2 being 5 or less. R 8 (This refers to a halogen atom, or a linear hydrocarbon group having 1 to 10 carbon atoms, or a branched or cyclic hydrocarbon group having 3 to 10 carbon atoms, where the -CH2- atoms constituting these groups may be substituted with -O-, -C(=O)-O-, or -C(=O)-, or may be substituted with a hydrogen atom, a halogen atom, or a heteroatom.)

[0033] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0034] [Resist composition] The resist composition of the present invention comprises a resin (A) having repeating units represented by the following general formula (p-1), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), A resin (B) having repeating units represented by the following general formula (p-2), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), The present invention provides a resist composition comprising a solvent (D) and a resin (A), wherein the content of resin (A) is less than the content of resin (B). [ka] (In general formula (p-1), R 1 This is a hydrogen atom or a methyl group. Z 1 It is a single bond, a phenylene group, -OZ 11 -, -C(=O)-OZ 11 -, -C(=O)-NH-Z 11 -, -Z 12 -Ph-, -Z 12 -O-Ph-, or -Z 12 -C(=O)-O-Ph- Z 11 This is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 12 is a hydrocarbon group with 1 to 15 carbon atoms, and Ph is a phenylene group. R 2 ~R 3 Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms, or a phenyl group. M 0- It is a non-nucleophilic counterion. In general formula (p-2), R4 is a hydrogen atom or a methyl group. Z 2 is a single bond, a phenylene group, -O-Z 21 -, -C(=O)-O-Z 21 -, -Z 21 -, -C(=O)-O-, or -C(=O)-NH-Z 21 -. Z 21 is a single bond, an alkanediyl group having 1 to 20 carbon atoms or an alkenediyl group having 2 to 20 carbon atoms, or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. M 1+ represents a counter cation having a substituent, and represents a sulfonium cation, an iodonium cation, an ammonium cation. R 5 is a hydrogen atom or a trifluoromethyl group. In general formula (a-1), R 6 is a hydrogen atom or a methyl group. Y is a group having a structure in which the polarity changes by the action of an acid and becomes soluble in an alkaline aqueous solution. In general formula (b-1), R 7 is a hydrogen atom or a methyl group. Z 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, an ester bond, an amide bond, -O-Z 31 -, -C(=O)-O-Z 31 - or -C(=O)-NH-Z 31 -. Z 31 is an alkanediyl group having 1 to 12 carbon atoms, and may contain a carbonyl group, an ester bond or an ether bond. n1 is an integer of 1 to 3, n2 is an integer of 0 to 3, and the sum of n1 and n2 is 5 or less. R 8 is a halogen atom, or a linear hydrocarbon group having 1 to 10 carbon atoms, a branched or cyclic hydrocarbon group having 3 to 10 carbon atoms, and -CH2- constituting these may be substituted with -O-, -C(=O)-O- or -C(=O)-, and may be substituted with a hydrogen atom, a halogen atom or a hetero atom.)

[0035] The above polymer compounds react to high-energy rays and heat, generating acid. Examples of high-energy rays in this invention include ultraviolet rays, far ultraviolet rays, electron beams, EUV (extreme ultraviolet rays), X-rays, excimer lasers, gamma rays, and synchrotron radiation.

[0036] As shown below, the resist film obtained from this composition is endowed with properties corresponding to each of the above repeating units.

[0037] (Meth)acrylic acid esters with a repeating unit (a-1) of an acid-unstable group benefit from having a relatively compact acid-unstable group, as this reduces swelling in alkaline developer after the acid-unstable group is removed by the generated acid, resulting in less pattern collapse.

[0038] Furthermore, if the resist composition has an anionic moiety of the photoacid generator as in the present invention in a polymer compound, the repeating unit (p-2) has a higher effect of suppressing acid diffusion compared to conventional additive-type photoacid generators, and a resist composition can be provided that has high resolution, exposure margin, excellent process adaptability, and good pattern shape after exposure. The above repeating unit (p-2) has an acidity such that the acid-unstable group can be removed by baking the (meth)acrylic acid ester having an acid-unstable group at a temperature of 150°C or lower.

[0039] Conventionally, having anionic moieties with weak acid groups in polymer compounds resulted in significantly poor solubility in resist solvents, and aggregation during polymer synthesis made it difficult to introduce repeating units with weak acid anionic moieties at high ratios. Therefore, the present invention provides excellent solvent solubility by having cationic moieties in polymer compounds, and enables the formation of salts with weak acids. It exhibits excellent distribution within the film and process adaptability, and the pattern shape after exposure is good.

[0040] The resist composition of the present invention can form a rigid film due to the ionic interaction between polymers by mixing a base polymer into which the above-mentioned repeating unit (p-2) anion is introduced and a base polymer into which the repeating unit (p-1) cation is introduced. Even in high exposure ranges, it suppresses solubility of alkaline developers, reduces edge roughness (LER, LWR) and dimensional uniformity of hole patterns (CDU) at high resolution, and produces a good pattern shape.

[0041] By combining the repeating unit (p-1) in the resist composition of the present invention with an onium salt, which is a weaker acid than α-fluoroalkanesulfonic acid, as a quencher component, the weak onium salt is generally non-volatile compared to nitrogen-containing compounds such as amines. This prevents changes in the concentration of the resist film surface during bake processes when forming the resist film or when patterning, resulting in good rectangular formation. Furthermore, by using an onium carboxylate salt (e-1), which has lower acidity and higher quenching ability than alkanesulfonic acid that does not have a fluorine atom at the α-position, the effect of suppressing acid diffusion is enhanced, resulting in high resolution, exposure margin, and excellent process adaptability. Adding a weak onium salt inhibits the ionic interaction between the anion-introduced base polymer and the cation-introduced base polymer, allowing for adjustment to a composite with appropriate resist performance.

[0042] In terms of dissolution contrast in alkaline developers, the resist composition of the present invention exhibits enhanced solubility in alkaline developers when the (meth)acrylate protected by acid-unstable groups that generate carboxylic acids decomposes, generating anionic moieties, or when cations decompose upon exposure, generating anionic moieties. When acid-unstable groups of the polymer are removed at low exposure levels, cations decompose upon exposure, generating anionic moieties, and their contribution to solubility can be ignored. However, at higher exposure levels, cations decompose upon exposure, generating anionic moieties, and their contribution to solubility can become significant.

[0043] The phenol group in the repeating unit (b-1) has a sensitizing effect on EB and EUV and suppresses swelling in alkaline developer. By having the phenol group in the polymer compound, the efficiency of secondary electron generation and sensitizing effect during exposure are increased in the resist composition, and the decomposition efficiency of the acid generator is increased, resulting in improved sensitivity.

[0044] In the solvent contained in the resist composition of the present invention, by increasing the proportion of polar solvent, it is possible to suppress the decrease in solubility in conventional resist solvents of a mixture of the anion-introduced base polymer and the cation-introduced base polymer, and to improve solubility.

[0045] The resist composition of the present invention, having the above configuration, suppresses the solubility of alkaline developer even in high exposure regions, reduces edge roughness (LER, LWR) and dimensional uniformity of hole patterns (CDU) at high resolution, and is a resist composition that can form a good pattern shape.

[0046] The following describes each component of the resist composition of the present invention.

[0047] <Resin (A)> [Repeating unit (p-1)] The resin (A) constituting the resist composition of the present invention has the following general formula (p-1) as a repeating unit.

[0048] [ka] (In general formula (p-1), R 1 This is a hydrogen atom or a methyl group. Z 1 It is a single bond, a phenylene group, -OZ 11 -, -C(=O)-OZ 11 -, -C(=O)-NH-Z 11 -, -Z 12 -Ph-, -Z 12 -O-Ph-, or -Z 12 -C(=O)-O-Ph- Z 11This is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 12 is a hydrocarbon group with 1 to 15 carbon atoms, and Ph is a phenylene group. R 2 ~R 3 Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms, or a phenyl group. M 0- (It is a non-nucleophilic counterion.)

[0049] Examples of monomers that provide a repeating unit (p-1) include, but are not limited to, those listed below.

[0050] [ka]

[0051] Non-nucleophilic counterion M 0- Examples include halide ions such as chloride ions and bromide ions; fluoroalkyl sulfonates such as triflate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate; aryl sulfonates such as tosylate, benzenesulfonate, 4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate; alkyl sulfonates such as mesylate and butanesulfonate; sulfonimide ions such as bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and bis(perfluorobutylsulfonyl)imide; sulfonmethides such as tris(trifluoromethylsulfonyl)methide and tris(perfluoroethylsulfonyl)methide; fluoroalkyl carboxylates such as trifluoromethylcarboxylate and nonafluorobutanecarboxylate; and alkyl carboxylates such as methylcarboxylate and benzenecarboxylate.

[0052] Non-nucleophilic counterion M 0-Examples of structures include, but are not limited to, those shown below.

[0053] [ka]

[0054] Aeon M 0- A structure represented by the following general formula (e-0) is preferred.

[0055] [ka] (In general formula (e-0), R 8b , R 9 Each of these independently represents a hydrogen atom, a fluorine atom, or a trifluoromethyl group. R 10 (This represents a hydrogen atom, a hydroxyl group, a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted alkyl group having 6 to 30 carbon atoms.)

[0056] Examples of structures represented by (e-0) are shown below, but are not limited to these.

[0057] [ka]

[0058] [ka]

[0059] Carboxylic acids have lower acid strength compared to sulfonium salts that generate alkanesulfonic acids, in which the α-position of a sulfonic acid is substituted with a fluorine atom, and alkanesulfonic acids in which the α-position of the sulfonic acid is not substituted with fluorine. Therefore, the cation of a carboxylic acid acts like a quencher by exchanging salts with alkanesulfonic acids in polymer compounds, such as polymer compounds with repeating units (p-2), in which the α-position is substituted with a fluorine atom. Carboxylic acids with lower acid strength have a greater quenching ability and increase contrast, resulting in superior rectangularity and edge roughness of the developed pattern.

[0060] When the sum of all repeating units of the polymer compound constituting the resist composition of the present invention is set to 1, the composition ratio (ratio of repeating units) of repeating units (p-1) is in the range of 0 < (p-1) ≤ 0.5, preferably 0.05 ≤ (p-1) ≤ 0.15.

[0061] [Repeating unit (a-1)] The polymer compound constituting the resist composition of the present invention has repeating units represented by the following general formula (a-1) whose polarity changes upon the action of an acid. [ka] (In general formula (a-1), R 6 This is a hydrogen atom or a methyl group. Y is a group whose polarity changes upon contact with an acid, making it soluble in alkaline aqueous solutions.

[0062] Specific examples of monomers that provide a repeating unit (a-1) are listed below, but are not limited to these. [ka]

[0063] [Repeating unit (b-1)] The polymer compound constituting the resist composition of the present invention has repeating units represented by the following general formula (b-1). [ka] (In general formula (b-1), R 7 This is a hydrogen atom or a methyl group. Z 3 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, ester bonds, amide bonds, and -OZ. 31 -, -C(=O)-OZ 31 -or -C(=O)-NH-Z 31 - is Z 31 This is an alkanediyl group having 1 to 12 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond. n1 is an integer between 1 and 3, and n2 is an integer between 0 and 3, with the sum of n1 and n2 being 5 or less. R 8 (This refers to a halogen atom, or a linear hydrocarbon group having 1 to 10 carbon atoms, or a branched or cyclic hydrocarbon group having 3 to 10 carbon atoms, where the -CH2- atoms constituting these groups may be substituted with -O-, -C(=O)-O-, or -C(=O)-, or may be substituted with a hydrogen atom, a halogen atom, or a heteroatom.)

[0064] Specific examples of the general formula (b-1) are listed below, but are not limited to these. [ka]

[0065] Because compounds containing phenolic hydroxyl groups have a sensitizing effect, the resist composition of the present invention exhibits excellent sensitivity and CDU.

[0066] [Lactone structure] The resin (A) may contain repeating units having a lactone structure. Furthermore, resin (A) does not necessarily have to contain repeating units having a lactone structure.

[0067] If the resin (A) is a resist composition that does not have a lactone structure, swelling can be suppressed by preventing the alkaline developer from seeping into the pattern, thereby providing a resist pattern with a more desirable shape.

[0068] When the sum of all repeating units in resin (A) is 1, the ratio of repeating units (p-1) is preferably 0.05 ≤ (p-1) ≤ 0.15, the ratio of repeating units (a-1) is preferably 0.4 < (a-1) ≤ 0.7, and the ratio of repeating units (b-1) is preferably 0.20 < (b-1) ≤ 0.45.

[0069] <Resin (B)> [Repeating unit (p-2)] The resin (B) constituting the resist composition of the present invention has repeating units represented by the following general formula (p-2).

[0070] [ka] (In general formula (p-2), R 4 This is a hydrogen atom or a methyl group. Z 2 It is a single bond, a phenylene group, -OZ 21 -, -C(=O)-OZ 21 -, -Z 21 -C(=O)-O-, or -C(=O)-NH-Z 21 - is Z 21 This group consists of a single bond, an alkanediyl group having 1 to 20 carbon atoms, an alkenediyl group having 2 to 20 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. M 1+ This represents a substituted countercation, specifically a sulfonium cation, iodonium cation, or ammonium cation. R 5 (This is either a hydrogen atom or a trifluoromethyl group.)

[0071] (p-2) M 1+Examples of structures of repeating unit monomers into which anions other than are introduced are shown below, but are not limited to these.

[0072] [ka]

[0073] M 1+ Examples of sulfonium cations include, but are not limited to, those listed below. In the following formulas, Me is a methyl group, nBu is an n-butyl group, and tBu is a tert-butyl group.

[0074] M 1+ Examples of iodonium cations include, but are not limited to, those listed below. In the following formulas, tBu is a tert-butyl group and Ph is a phenyl group.

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] M 1+ Specific examples of ammonium cations include, but are not limited to, those listed below. [ka]

[0079] When the sum of all repeating units of the polymer compound constituting the resist composition of the present invention is set to 1, the composition ratio (ratio of repeating units) of repeating units (p-2) is in the range of 0 < (p-2) ≤ 0.5, preferably 0.1 ≤ (p-2) ≤ 0.25.

[0080] By incorporating an anionic structure of a photoacid generator into the polymer backbone, acid diffusion is reduced, preventing a decrease in resolution due to blurring caused by acid diffusion. Furthermore, the uniform dispersion of the acid generator improves edge roughness (LER, LWR).

[0081] [Repeating unit (a-1)] The repeating unit (a-1) can be the same as that described above in the section on resin (A).

[0082] [Repeating unit (b-1)] The repeating unit (b-1) can be the same as that described above in the section on resin (A).

[0083] [Lactone structure] The resin (B) may contain repeating units having a lactone structure. Furthermore, resin (B) does not necessarily have to contain repeating units having a lactone structure.

[0084] If the resin (B) is a resist composition that does not have a lactone structure, swelling can be suppressed by reducing the penetration of the alkaline developer into the pattern, thereby providing a resist pattern with a more desirable shape. When the sum of all repeating units in resin (B) is 1, the ratio of repeating units (p-2) is preferably 0.1 ≤ (p-2) ≤ 0.25, the ratio of repeating units (a-1) is preferably 0.4 ≤ (a-1) < 0.7, and the ratio of repeating units (b-1) is preferably 0.2 < (b-1) ≤ 0.4.

[0085] <Resin (C)> The resist composition of the present invention may further contain a resin (C), and it is preferable that the resin (C) does not contain repeating units whose polarity changes upon the action of an acid and become soluble in an alkaline aqueous solution. A resist composition containing resin (C) can improve the uniformity of the film thickness within the wafer surface of a resist film coated by spin coating.

[0086] Furthermore, it is preferable that the above resin (C) has repeating units represented by the following general formula (c-1). [ka] (In general formula (c-1), R 11 This is a hydrogen atom or a methyl group. X 1 This refers to a single bond or a divalent linking group, which is a divalent hydrocarbon group having 1 to 10 carbon atoms (such as a methylene group, ethylene group, or phenylene group), a fluorinated phenylene group, or -OX. 11 -, -C(=O)-OX 11 -or -C(=O)-NH-X 11 - It is one of the following. 11 This is an alkanediyl group having 1 to 20 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond.

[0087] By adding a polymer having such a fluoroalcohol structure, the uniformity of the resist film coating can be improved, and its dissolution in alkaline developer can be promoted.

[0088] The repeating units represented by the above general formula (c-1) include, but are not limited to, the following. [ka] The ratio of resin (A) and resin (C) in the resist composition is preferably such that, with respect to 100 parts by mass of the total of resin (A) and resin (B), the ratio of resin (A) is greater than 10 parts by mass but less than 50 parts by mass, and the ratio of resin (C) is preferably greater than 0 parts by mass but less than 20 parts by mass, and more preferably greater than 3 parts by mass but less than 8 parts by mass.

[0089] <Onium salt (E)> The resist composition of the present invention may contain an onium salt (E) represented by the following general formula (e-1). [ka] (In general formula (e-1), R 12 ~R 13 Each of these independently represents a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 10 carbon atoms which may contain a fluorine atom, or a trifluoromethyl group. R 14 This represents a linear alkyl group having 1 to 20 carbon atoms, or a branched or cyclic alkyl group having 3 to 20 carbon atoms, which may contain hydrogen atoms, hydroxyl groups, ether bonds, and ester bonds, either substituted or unsubstituted, or an aryl group having 6 to 30 carbon atoms. M 2+ (This indicates a substituted countercation, representing a sulfonium cation or an iodonium cation.)

[0090] Specific examples of anionic structures in general formula (e-1) are shown below, but are not limited to these. [ka]

[0091] [ka]

[0092] The cation structure M of the above general formula (e-1) 2+ As sulfonium cations, iodonium cations are M 1+ Similar structures can be shown, but are not limited to these.

[0093] The amount of these onium salts (E) added is 0 to 40 parts by mass per 100 parts by mass of the total of resin (A) and resin (B) in the resist composition, preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 20 parts by mass. Within the above range, there is no risk of deterioration of resolution or problems with foreign matter occurring after resist development or during peeling.

[0094] Carboxylic acids have lower acid strength compared to sulfonium salts that generate alkanesulfonic acids, in which the α-position of a sulfonic acid is substituted with a fluorine atom, and alkanesulfonic acids in which the α-position of the sulfonic acid is not substituted with fluorine. Therefore, the cation of a carboxylic acid acts like a quencher by exchanging salts with alkanesulfonic acids in polymer compounds, such as polymer compounds with repeating units (p-2), in which the α-position is substituted with a fluorine atom. Carboxylic acids with lower acid strength have a greater quenching ability and increase contrast, resulting in superior rectangularity and edge roughness of the developed pattern.

[0095] [Solvent (D)] The solvent used in the present invention may be any organic solvent capable of dissolving polymer compounds, photoacid generators, quenchers, and other additives. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-amyl ketone as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, and propylene glycol monoethyl ether. Examples include ethers such as methyl ether and diethylene glycol dimethyl ether, esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, ethyl 2-hydroxybutyrate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, lactones such as γ-butyrolactone, and mixed solvents thereof. When using acetal-based acid-unstable groups, high-boiling point alcohol-based solvents, specifically diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc., can be added to accelerate the deprotection reaction of the acetal.

[0096] In the present invention, among these organic solvents, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, propylene glycol dimethyl ether, ethyl lactate, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and mixed solvents thereof are preferably used, as they exhibit particularly excellent solubility for salt structure-containing polymers in the resist component.

[0097] The solvent (D) contained in the resist composition of the present invention preferably has a high proportion of highly polar solvents. When such a solvent is used, the solubility does not decrease even when resin (A) and resin (B) are mixed, striations do not occur during coating, and the uniformity of the film thickness does not deteriorate.

[0098] In the present invention, the amount of organic solvent used is preferably 200 to 7,000 parts by mass per 100 parts by mass of the total of resin (A) and resin (B), and more preferably 300 to 5,000 parts by mass.

[0099] The solvent included in the present invention is preferably a mixed solution with propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, etc., which have excellent coating properties. The amount of organic solvent used is preferably 200 to 4,000 parts by mass per 100 parts by mass of the total of resin (A) and resin (B), and more preferably 300 to 3,000 parts by mass, if limited to this solvent propylene glycol monomethyl ether acetate (PGMEA).

[0100] [Other ingredients] The resist composition of the present invention may optionally include other quenchers such as nitrogen-containing compounds and surfactants.

[0101] (nitrogen-containing compounds) The present invention also allows for the addition of nitrogen-containing compounds as quenchers. By adding these, the diffusion rate of the acid generated from the photoacid generator when it diffuses into the resist film can be suppressed. Examples of such nitrogen-containing compounds include primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103, particularly amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond. Furthermore, compounds in which a primary or secondary amine is protected with a carbamate group, such as the compound described in Japanese Patent Publication No. 3790649, can also be cited.

[0102] These quenchers can be used individually or in combination of two or more types, and the preferred amount is 0.001 to 12 parts by mass, particularly 0.01 to 8 parts by mass, per 100 parts by mass of base resin. The addition of quenchers makes it easier to adjust the resist sensitivity, suppresses the diffusion rate of acid in the resist film, improves resolution, suppresses sensitivity changes after exposure, reduces substrate and environmental dependence, and improves exposure margin and pattern profile. Furthermore, the addition of these quenchers can also improve substrate adhesion.

[0103] Furthermore, the resist composition of the present invention may also contain a photoacid generator having a nitrogen-containing substituent. Such a compound functions as a quencher in the unexposed areas and loses its quenching ability in the exposed areas through neutralization with its own generated acid, functioning as a so-called photodecayable base. By using a photodecayable base, the contrast between the exposed and unexposed areas can be further enhanced. Examples of photodecayable bases can be found in Japanese Patent Publication No. 2009-109595 and Japanese Patent Publication No. 2012-46501.

[0104] (Surfactants) A surfactant may be added to the resist composition of the present invention. Examples of surfactants include surfactants that are insoluble or sparingly soluble in water and soluble in alkaline developers, and / or surfactants (hydrophobic resins) that are insoluble or sparingly soluble in water and alkaline developers. For example, one can refer to the (S) defined components described in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2011-16746. As surfactants that are insoluble or poorly soluble in water and alkaline developers, FC-4430, Surflon S-381, Surfinol E1004, KH-20, KH-30, and the oxetane ring-opening polymer shown in the following structural formula (surf-1) are preferred among the surfactants listed in the above publication. These can be used individually or in combination of two or more.

[0105] [ka]

[0106] Here, R, Rf, A, B, C, m, and n apply only to the above formula (surf-1), notwithstanding the above description. R represents a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Specifically, divalent examples include ethylene, 1,4-butylene, 1,2-propylene, 2,2-dimethyl-1,3-propylene, and 1,5-pentylene, while trivalent or tetravalent examples include the following.

[0107] [ka] (In the formula, the dashed lines indicate bonds, which are substructures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0108] Among these, 1,4-butylene or 2,2-dimethyl-1,3-propylene are preferred. Rf represents a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m represents the valence of R, which is an integer from 2 to 4. A represents 1, B is an integer from 2 to 25, and C is an integer from 0 to 10. Preferably, B is an integer from 4 to 20, and C is 0 or 1. Furthermore, the arrangement of each structural unit in the above structure is not specified and may be block-like or randomly bonded. For details on the production of partially fluorinated oxetane ring-opening polymer surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0109] Surfactants that are insoluble or sparingly soluble in water but soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the resist surface after spin coating when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful in suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. Furthermore, they are useful because they become solubilized during alkaline development after exposure and post-exposure baking (PEB), and are less likely to become foreign substances that cause defects. Such surfactants are insoluble or sparingly soluble in water but soluble in alkaline developers, and are polymeric surfactants, also called hydrophobic resins. Even in dry exposure, they can improve the solubility of the sparingly soluble surface layer, thereby reducing defects. Those that improve solubility in alkaline developers are particularly preferred. They also have the effect of improving the uniformity of the film thickness of the coating.

[0110] Resin (C) is a polymeric surfactant, and examples include those listed below. [ka]

[0111] In the formula, R e1 These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. e2 Each is independently a hydrogen atom, or a linear, branched, or cyclic alkyl group or fluorinated alkyl group having 1 to 20 carbon atoms, and within the same repeating unit R e2 These may bond to each other to form a ring with the carbon atoms to which they are bonded, in which case the total number of atoms is linear, branched, or cyclic alkylene groups or fluorinated alkylene groups having 2 to 20 carbon atoms.

[0112] R e3 is a hydrogen atom or a fluorine atom, or R e4 They may bond with each other to form a non-aromatic ring with 3 to 10 carbon atoms. e4R is a linear, branched, or cyclic alkylene group having 1 to 6 carbon atoms, and one or more hydrogen atoms may be substituted with fluorine atoms. e5 R is a linear or branched alkyl group having 1 to 10 carbon atoms in which one or more hydrogen atoms are replaced by fluorine atoms. e4 and R e5 These may bond together to form a non-aromatic ring with the carbon atom to which they are bonded, in which case R e4 , R e5 And these bond to carbon atoms, forming trivalent organic groups with 3 to 12 carbon atoms. e6 This is a single bond or an alkylene group having 1 to 4 carbon atoms.

[0113] R e7 These are, independently, single bonds, -O-, or -CR bonds. e1 R e1 - is R e8 R is a linear or branched alkylene group having 1 to 4 carbon atoms, and within the same repeating unit e2 They may bond with each other to form a non-aromatic ring with 3 to 6 carbon atoms.

[0114] R e9 This is a methylene group, a 1,2-ethylene group, a 1,3-propylene group, or a 1,4-butylene group. e10 These are a linear perfluoroalkyl group having 3 to 6 carbon atoms, a 3H-perfluoropropyl group, a 4H-perfluorobutyl group, a 5H-perfluoropentyl group, or a 6H-perfluorohexyl group.

[0115] L e These are, independently, -C(=O)-O-, -O-, or -C(=O)-R. e11 -C(=O)-O- and R e11 This is a linear, branched, or cyclic alkylene group having 1 to 10 carbon atoms.

[0116] Furthermore, 0≦(a'-1)≦1, 0≦(a'-2)≦1, 0≦(a'-3)≦1, 0≦b'≦1, and 0≦c'≦1, and 0<(a'-1)+(a'-2)+(a'-3)+b'+c'≦1.

[0117] Specific examples of the repeating units are shown below, but are not limited to these. Note that in the following formula, R e1 This is the same as described above. [ka]

[0118] The Mw of the polymeric surfactant is preferably 1,000 to 50,000, and more preferably 2,000 to 20,000. Within this range, the surface modification effect is sufficient, and development defects are less likely to occur.

[0119] For the aforementioned surfactants that are insoluble or sparingly soluble in water and soluble in alkaline developing solutions, please also refer to Japanese Patent Publication No. 2008-122932, Japanese Patent Publication No. 2010-134012, Japanese Patent Publication No. 2010-107695, Japanese Patent Publication No. 2009-276363, Japanese Patent Publication No. 2009-192784, Japanese Patent Publication No. 2009-191151, Japanese Patent Publication No. 2009-98638, Japanese Patent Publication No. 2010-250105, Japanese Patent Publication No. 2011-42789, etc.

[0120] The amount of surfactant to be added is 0 to 20 parts by mass per 100 parts by mass of resist solids, but if added, the lower limit is preferably 0.001 parts by mass, and more preferably 1 part by mass. On the other hand, the upper limit is preferably 15 parts by mass, and more preferably 5 parts by mass.

[0121] [Pattern formation method] The present invention further relates to a pattern forming method in which a resist film is formed on a substrate using the resist composition described above, a mask is placed over the resist film, high-energy rays are irradiated to expose it, and then the film is developed with an alkaline developer to form a pattern on the substrate, (i) A step of forming a resist film on a substrate using the resist composition of the present invention described above, (ii) Exposing the resist film with a KrF excimer laser with a wavelength of 248 nm, an ArF excimer laser with a wavelength of 193 nm, EUV lithography with a wavelength of 13.5 nm, or an electron beam, (iii) A step of developing the exposed resist film with an alkaline developer, The present invention provides a pattern formation method that includes [specific details].

[0122] To form a pattern using the resist composition of the present invention, known lithography techniques can be employed. For example, a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi, etc.) is coated with the resist composition to a thickness of 0.05 to 2.0 μm using a method such as spin coating. This is then pre-baked on a hot plate at 60 to 150°C for 1 to 10 minutes, preferably at 80 to 140°C for 1 to 5 minutes. Next, a mask for forming the desired pattern is placed over the resist film, and a high-energy beam such as a KrF excimer laser, ArF excimer laser, or EUV is exposed at an exposure dose of 1 to 200 mJ / cm². 2 Preferably 10-100 mJ / cm² 2 The irradiation is performed in such a manner. Exposure can be performed using the normal exposure method, or in some cases, the immersion method, in which the space between the mask and the resist film is immersed in liquid. In that case, a water-insoluble protective film can also be used. Next, post-exposure baking (PEB) is performed on a hot plate at 60-150°C for 1-5 minutes, preferably at 80-140°C for 1-3 minutes. Furthermore, development is performed using a developer solution of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1-5% by mass, preferably 2-3% by mass, for 0.1-3 minutes, preferably 0.5-2 minutes, by a conventional method such as the dip method, puddle method, or spray method to form the desired pattern on the substrate.

[0123] Furthermore, as described above, the developing solution for the pattern forming method of the present invention can be an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1 to 5% by mass, preferably 2 to 3% by mass. [Examples]

[0124] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these descriptions.

[0125] The structure of each repeating unit is shown below.

[0126] [(p-1) units] [ka]

[0127] [(p-2) units] [ka]

[0128] [(a-1) units] [ka]

[0129] [(b-1) units] [ka]

[0130] [Lactone units] [ka]

[0131] [Polymer Synthesis Example 1] (Polymer synthesis example: PA-1) Under a nitrogen atmosphere, 6.6 g of monomer P1-1, 7.0 g of monomer A-1, 6.4 g of monomer B-1, 0.24 g of V-601 (2,2'-azobis(isobutyrate)dimethyl, manufactured by Wako Pure Chemical Industries, Ltd.), 0.2 g of 2-mercaptoethanol, and 25 g of methyl ethyl ketone were placed in a flask to prepare a monomer-polymerization initiator solution. 23 g of methyl ethyl ketone was placed in another flask under a nitrogen atmosphere and heated to 80°C with stirring. The monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition was complete, the polymerization solution was kept at 80°C and stirred for 2 hours, then cooled to room temperature. The obtained polymerization solution was added dropwise to 400 g of hexane with vigorous stirring, and the precipitated polymer was filtered off. The polymer was washed twice with 120 g of hexane and then vacuum-dried at 50°C for 20 hours to obtain 18 g of white powdered polymer PA-1.

[0132] [Polymer Synthesis Example 2] (Examples of polymer synthesis: PA-2 to PA-21, PB-1 to PB-15, P-1, P-2) Polymers PA-2 to PA-21, PB-1 to PB-15, P-1, and P-2 were synthesized using the same procedure as for polymer synthesis example PA-1, with the monomer compositions and introduction ratios (molar ratios) shown in Tables 1 and 2.

[0133] [Table 1]

[0134] [Table 2]

[0135] [Preparation of resist composition] Next, the resin (A) is represented by polymers PA-1 to 21, and the resin (B) is represented by polymers PB-1 to 15. The resin (A) and the resin (B) are mixed, and the total amount of the resin (A) and the resin (B) added at that time is set to 100 parts by mass. Tables 3 and 4 show the amounts added of the solvent (D), the resin (C), and the additives (onium salt 1, onium salt 2, nitrogen-containing compound) when the total amount of the resin (A) and the resin (B) added is 100 parts by mass, in parts by mass. As the surfactant, 100 ppm of FC-4430, a surfactant manufactured by Sumitomo 3M Limited, was dissolved, and after dissolution, it was filtered through a Teflon (registered trademark) filter (pore diameter 0.2 μm) to prepare the resist compositions shown in Tables 3 and 4 below.

[0136] The solvents shown in Tables 3 to 5 are as follows. PGMEA: Propylene glycol monomethyl ether acetate PGME: Propylene glycol monomethyl ether EL: Ethyl lactate HBM: 4-Hydroxy-4-methyl-2-pentanone GBL: γ-Butyrolactone

[0137] [Resin (C)] [Chemical formula]

[0138] The compositions of onium salt 1, onium salt 2, and the nitrogen-containing compound are shown below. [Onium salt 1] [Chemical formula]

[0139] [Onium salt 2] [Chemical formula]

[0140] [Nitrogen-containing compound] [Chemical formula]

[0141] [Table 3]

[0142] [Table 4]

[0143] [Evaluation of DLS particle size using dynamic light scattering method] Dynamic light scattering (DLS) was used to measure the particle size of a polymer solution adjusted to 1.5 wt% using a DynaPro NanoSter (Wyatt Technology). In this invention, polymers PA-6 and PB-5, and mixtures thereof, were measured under the conditions shown in the table below. It was confirmed that mixing the polymers resulted in larger DLS particle sizes than the polymers alone, suggesting the formation of a polymer composite.

[0144] [Table 5]

[0145] [EUV exposure patterning evaluation (line pattern evaluation)] The resist compositions of the present invention (R-1 to R-23) and the comparative resist compositions (R-24 to R-32) were coated on a substrate on which an organic antireflection film AL-412 with a film thickness of 20 nm manufactured by Brewer Science was formed using a Clean Track Lithius ProZ manufactured by Tokyo Electron, baked on a hot plate at 105 °C for 60 seconds, and a 50-nm resist film was formed. Using an EUV exposure machine NXE3400 manufactured by ASML, a line & space pattern with a dimension of 20 nm and a pitch of 40 nm on the mask was exposed. After applying an appropriate PEB temperature for each resist composition after exposure, a 2.38% aqueous solution of tetramethylammonium was discharged while rotating on the wafer, developed for a total of 30 seconds, the alkaline solution was rinsed off with water, and the wafer was rotated at high speed to remove the water.

[0146] (Sensitivity evaluation) The fabricated resist pattern was observed with a CD-SEM CG-6300 manufactured by Hitachi High-Technologies, and the exposure dose at which the line pattern becomes 20 nm at a pitch of 40 nm was defined as the optimum exposure dose Eop (mJ / cm 2 ).

[0147] (Line width roughness (LWR) evaluation) The obtained hole pattern was observed with a CD-SEM CG-6300 manufactured by Hitachi High-Technologies. The CD width of 32 points was measured for each line, the line widths of 11 lines were measured from one SEM image, and the variation in the CD width was defined as LWR. A smaller LWR value means better dimensional uniformity. An LWR of 3.0 or less was considered good.

[0148] Also for the resist compositions of the present invention, the resist coating property was evaluated by the same evaluation method as for the polymer solution. If the Range is 10 Å or more, it is marked as ×; if it is 10 to 5 Å, it is marked as Δ; if it is 5 Å or less, it is marked as good 〇. The results are shown in Tables 6 and 7.

[0149] [Evaluation of coating property of resist composition] The coatability of the prepared resist composition on a silicon wafer substrate was investigated. A 50 nm resist film was formed by coating a 300 mm silicon wafer substrate using Tokyo Electron's CleanTrack Lithius ProAP and baking it on a hot plate at 105°C for 60 seconds. The film thickness was measured using a SCREEN VM3210 optical interferometry film thickness analyzer. The difference between the maximum and minimum film thickness at 11 measurement points was defined as Range (Å). A Range of 10 Å or more was marked with ×, 10 to 5 Å with a △, and 5 Å or less with a ○. The results are shown in Tables 6 and 7.

[0150] [Table 6]

[0151] [Table 7]

[0152] As shown in Tables 6 and 7, the resist compositions of the present invention (Examples 1 to 23) had good LWRs of 3.0 or less, while the LWRs of Comparative Examples 1 to 9 were above 3.0.

[0153] Among the comparative examples (Comparative Examples 1 to 9), in cases such as Comparative Examples 1 to 4, where the amount of resin (A) was greater than the amount of resin (B), and resin (A) accounted for a large portion of the resist solid content, the reactivity of the acid leaving group was poor due to the small amount of strongly acidic components, and the LWR value did not meet the range of LWR 3.0 or less.

[0154] Conversely, as in Comparative Examples 5 and 6, when resin (B) constitutes a large portion of the resist solid content, as can be seen from the small DLS particle size of resin (B) in Table 5, the exposed areas tend to attract alkaline developer, resulting in greater variation at the pattern interface and failing to meet the LWR 3.0 or lower numerical range.

[0155] The resist composition of the present invention forms a polymer composite by mixing resin (A) and resin (B) such that resin (A) is less abundant than resin (B), and it has been shown to be useful in alkaline aqueous solution development processes because it can form a pattern with excellent LWR even in high exposure regions.

[0156] The results in Tables 6 and 7 show that the resist composition of the present invention exhibits excellent coatability when it contains resin (C).

[0157] The results above demonstrate that the resist composition of the present invention can form a resist film with a low LWR. Therefore, the present invention demonstrates that it can provide a resist composition that reduces roughness (LER, LWR) and dimensional uniformity of the hole pattern (CDU) at a higher resolution than conventional resist materials, and has good pattern shape after exposure and excellent etching resistance.

[0158] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A resin (A) having repeating units represented by the following general formula (p-1), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), A resin (B) having repeating units represented by the following general formula (p-2), repeating units whose polarity changes upon the action of an acid represented by the following general formula (a-1) and which become soluble in an alkaline aqueous solution, and repeating units represented by the following general formula (b-1), Solvent (D), A resist composition comprising, A resist composition characterized in that the content of resin (A) contained in the resist composition is less than the content of resin (B). 【Chemistry 1】 (In general formula (p-1), R １ This is a hydrogen atom or a methyl group. Z １ is a single bond, a phenylene group, -O-Z １１ -, -C(=O)-O-Z １１ -, -C(=O)-NH-Z １１ -, -Z １２ -Ph-, -Z １２ -O-Ph-, or -Z １２ -C(=O)-O-Ph-. Z １１ is an alkanediyl group having 1 to 6 carbon atoms or an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond or a hydroxy group. Z １２ is a hydrocarbon group having 1 to 15 carbon atoms, and Ph is a phenylene group. R ２ ~R ３ Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms, or a phenyl group. M ０－ This is a non-nucleophilic counterion represented by the following general formula (e-0). 【Chemistry 2】 (In general formula (e-0), R8b and R9 each independently represent a hydrogen atom, a fluorine atom, or a trifluoromethyl group.) R 10 represents a hydrogen atom, a hydroxyl group, a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 6 to 30 carbon atoms, either substituted or unsubstituted, or an aryl group having 6 to 30 carbon atoms. In general formula (p-2), R ４ This is a hydrogen atom or a methyl group. Z ２ It consists of a single bond, a phenylene group, and an -O-Z bond. ２１ -, -C(=O)-O-Z ２１ -, -Z ２１ -C(=O)-O-, or -C(=O)-NH-Z ２１ - is Z ２１ This is a single bond, an alkanediyl group having 1 to 20 carbon atoms, an alkenediyl group having 2 to 20 carbon atoms, or a phenylene group, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. M １＋ This represents a substituted countercation, specifically a sulfonium cation, iodonium cation, or ammonium cation. R ５ This is either a hydrogen atom or a trifluoromethyl group. In general formula (a-1), R ６ This is a hydrogen atom or a methyl group. Y is a group that has a structure in which its polarity changes upon the action of an acid, making it soluble in alkaline aqueous solutions. In general formula (b-1), R ７ This is a hydrogen atom or a methyl group. Z ３ These are single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, ester bonds, amide bonds, and -O-Z. ３１ -, -C(=O)-O-Z ３１ - or -C (=O)-NH-Z ３１ - is Z ３１ This is an alkanediyl group having 1 to 12 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond. n1 is an integer between 1 and 3, and n2 is an integer between 0 and 3, with the sum of n1 and n2 being 5 or less. R ８ These are halogen atoms, or linear hydrocarbon groups having 1 to 10 carbon atoms, branched hydrocarbon groups having 3 to 10 carbon atoms, or cyclic hydrocarbon groups, and these constitute -CH ２ The - may be substituted with -O-, -C(=O)-O-, or -C(=O)-, and may also be substituted with a hydrogen atom, a halogen atom, or a heteroatom.

2. The resist composition according to claim 1, characterized in that the resin (A) and the resin (B) do not contain repeating units having a lactone structure.

3. The resist composition according to claim 1, further comprising a resin (C), wherein the resin (C) does not contain repeating units whose polarity changes upon the action of an acid and which become soluble in an alkaline aqueous solution.

4. The resist composition according to claim 3, characterized in that the resin (C) has repeating units represented by the following general formula (c-1). 【Transformation 3】 (In general formula (c-1), R １１ This is a hydrogen atom or a methyl group. X １ This is a single bond or a divalent linking group, which is a divalent hydrocarbon group having 1 to 10 carbon atoms, a fluorinated phenylene group, or -O-X １１ -, -C(=O)-O-X １１ - or -C (=O)-NH-X １１ It is one of the following: X １１ (This is an alkanediyl group having 1 to 20 carbon atoms, and may contain a carbonyl group, an ester bond, or an ether bond.)

5. The resist composition according to claim 1, characterized in that it further comprises an onium salt (E) represented by the following general formula (e-1). 【Chemistry 4】 (In general formula (e-1), R １２ ~R １３ Each of these independently represents a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 10 carbon atoms which may contain a fluorine atom, or a trifluoromethyl group. R １４ This represents a linear substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a branched or cyclic substituted or unsubstituted alkyl group having 3 to 20 carbon atoms, which may contain hydrogen atoms, hydroxyl groups, ether bonds, and ester bonds, or an substituted or unsubstituted aryl group having 6 to 30 carbon atoms. M ２＋ (This represents a substituted countercation, specifically a sulfonium cation or iodonium cation.)

6. The resist composition according to claim 1, characterized in that the solvent (D) is a mixed solvent selected from two or three of the following: propylene glycol monomethyl ether acetate and propylene glycol dimethyl ether, ethyl lactate, γ-butyrolactone, and 4-hydroxy-4-methyl-2-pentanone.

7. A pattern formation method, (i) A step of forming a resist film on a substrate using the resist composition according to any one of claims 1 to 6, (ii) A step of exposing the resist film with a KrF excimer laser with a wavelength of 248 nm, an ArF excimer laser with a wavelength of 193 nm, EUV lithography with a wavelength of 13.5 nm, or an electron beam, (iii) A step of developing the exposed resist film with an alkaline developer, A pattern forming method characterized by including the following.

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