Patterning process

Abstract

The present invention addresses the problem of providing a patterning method that uses a (meth)acrylic acid polymer suitable for ArF patterning as a main framework, and obtains a narrow-pitch micro-pattern by dry development (dry development) instead of siliconeization. The solution to this problem is a patterning method comprising the following steps: forming a multilayer on a substrate; forming a resist upper layer film using an ArF excimer positive chemical amplification resist composition; removing acid-labile groups from the exposed portions of the resist upper layer film by exposure and post-exposure baking; performing a hard bake at a higher temperature and for a shorter time than the post-exposure baking, causing the removed acid-labile groups to volatilize outside the resist upper layer film; creating a carbon number difference between the unexposed and exposed portions; separating the pattern by dry development using an oxygen-containing gas plasma; and etching and transferring the pattern of the resist upper layer film to the underlying multilayer.

Description

Technical Field

[0001] This invention relates to a pattern forming method. Prior Technology

[0002] To achieve high integration in semiconductor manufacturing devices, microfabrication technology continues to advance. Lithography and dry etching are important manufacturing process technologies supporting microfabrication, and the resist materials used in these processes are crucial in determining the processing dimensions.

[0003] In the microfabrication of DRAM (Dynamic Random Access Memory) circuits used in state-of-the-art semiconductor devices such as HBM (High Bandwidth Memory), ArF immersion technology with an exposure wavelength of 193nm is still widely used. In particular, for narrow pitch patterns of about 40nm line spacing (80nm pattern pitch), the so-called double patterning technology, which combines multilayer process technology of combined lithography and CVD film deposition technology to double the pattern pitch, is often used.

[0004] When ultimately forming line and spacing patterns with narrow pitches below 40 nm, the resist material often uses ArF positive chemical amplification resists, where the exposed portion dissolves in an alkaline aqueous solution to form the pattern. One reason for this is that it offers superior resolution compared to ArF negative resists, which use organic solvents and leave residues in the exposed portion.

[0005] However, in ArF positive resists with high resolution, a non-negligible roughness of the pattern edge becomes required. One known cause of this pattern edge roughness is the swelling effect of the resist caused by the alkaline aqueous solution of TMAH (tetramethylamine hydroxide) developer, and the effect of bending and wiggling of the resist pattern during the drying step after development and cleaning.

[0006] Manufacturers of resist materials are developing polymer compositions that reduce the swelling effect relative to aqueous solutions, low-diffusion photocatalyst materials that improve positive resolution, and optimizing the composition of such resist materials and the conditions of use in order to reduce the pattern edge roughness of ArF resists.

[0007] On the other hand, in the field of lithography and microfabrication technology other than ArF immersion exposure, in order to avoid pattern swelling caused by wet development, one of the causes of pattern edge roughness, patterning by dry development is being studied.

[0008] As an example of applying the dry development process, it has been reported that a method for patterning by dry development is carried out by siliconeizing chemical amplification positive resist components such as styrene and phenolic varnish (Patent Documents 1 and 2).

[0009] Furthermore, there are reports of a dry development method that uses a non-chemically amplifying resist that reverses positive and negative values ​​by controlling the temperature of the substrate to be dry developed (Patent Document 3).

[0010] Furthermore, there are reports on resist materials corresponding to exposure wavelengths of 300-500 nm, which utilize acid-instable groups to replace phenolic hydroxyl groups, thereby generating an etching rate difference between the exposed and unexposed areas through the removal of these acid-instable groups and dry development containing oxygen (Patent Document 4).

[0011] Furthermore, there are reports of using the film thickness difference between the exposed and unexposed areas, generated by the ideal volume change rate before and after exposure of the chemical amplification inhibitor, for pattern separation (Patent Document 5). [Previous Technical Documents] [Patent Literature]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 07-022304 [Patent Document 2] Japanese Patent Application Publication No. 2004-103926 [Patent Document 3] Japanese Patent Application Publication No. 07-161607 [Patent Document 4] Japanese Patent Application Publication No. 2018-136536 [Patent Document 5] Japanese Patent Application Publication No. 2023-157346 Summary of the Invention

[0013] [The problem that the invention aims to solve] However, while siliconization technology is an effective alternative to dry etching, it requires specialized equipment for siliconization, the process is complex, and the risk of defects increases with each additional step.

[0014] Furthermore, a research report on resist patterning with negative and positive reversal techniques focuses on non-chemically amplified resists such as polyvinylphenol and cresol phenolic varnishes. Although there are records for PMMA, the method of directly decomposing the main chain of PMMA polymer with energy rays for patterning suffers from insufficient etch resistance and exposure sensitivity, making it difficult to apply to current high-productivity manufacturing mass production technologies.

[0015] Furthermore, reports indicate that research on dry development utilizing the ideal volume change rate before and after exposure aims to obtain patterns without adding special resists or steps. A film thickness difference of over 45% between the unexposed and exposed areas is sufficient to form a dry-developed pattern. However, to achieve a larger ideal volume change, a high substitution rate (e.g., protection with 100% acid-degradable groups) is used to replace the base polymer. To achieve the desired high deprotection reaction, a larger exposure is required. Alternatively, alternative exposure levels can be used, requiring high-temperature PEB to promote deprotection. However, high-temperature PEB increases acid diffusion length, leading to reduced microprocessability.

[0016] The present invention was made in view of the foregoing circumstances, and its purpose is to provide a patterning method for obtaining narrow-pitch micro-patterns by using a (meth)acrylic acid polymer that can be used for ArF patterning on a main skeleton and by dry development (dry development) rather than siliconeization. [Methods for solving problems]

[0017] To address the aforementioned issues, this invention provides a pattern forming method comprising the following steps: Forming multiple layers on the substrate being processed An ArF excimer positive chemical amplification system inhibitor composition is used to form an inhibitor top film by comprising at least a base polymer having a (meth)acrylic acid structure substituted with an acid-instable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent. The acid-indestructible groups in the exposed portion of the aforementioned resist upper film are removed through exposure and post-exposure baking. A harder bake, performed at a higher temperature and for a shorter time than the previously described post-exposure bake, is used to volatilize the aforementioned detached acidic unstable groups to the outer layer of the aforementioned resist film, creating a difference in the number of carbons between the unexposed and exposed areas. Using an oxygen-containing gaseous plasma, the resist layer film of the aforementioned exposure section is removed by dry development to separate the pattern and... The pattern of the aforementioned upper layer of the resist film is etched and transferred to the aforementioned multilayer layer below.

[0018] According to this patterning method, a (meth)acrylic acid polymer that can be used for ArF patterning can be used on the main skeleton, and a narrow-pitch micro-pattern can be obtained by dry development (dry development) instead of siliconeization.

[0019] Furthermore, in this invention, for the aforementioned basic polymer, it is preferable to use a (meth)acrylic acid structure having a substitution rate of 80% to 100% for the aforementioned acid-unstable group, and the aforementioned acid-unstable group having 4 to 9 carbon atoms.

[0020] By using a resist composition containing such a basic polymer, a predetermined dry development selectivity ratio between the unexposed and exposed portions can be obtained.

[0021] Furthermore, in this invention, for the aforementioned base polymer, those without a lactone structure can be used.

[0022] Even when using a resist composition containing such a base polymer, exposure and subsequent baking, as well as dry development and subsequent dry etching transfer of multiple layers to the next layer, can be performed well.

[0023] Furthermore, in this invention, the aforementioned exposure baking is performed at 80°C to 120°C for 40 to 120 seconds, and the aforementioned hard baking is performed at 130°C or above for less than 40 seconds.

[0024] By performing exposure baking and hard baking at such temperatures and times, the deprotection reaction and volatilization of acid unstable groups can be carried out more reliably.

[0025] Furthermore, in this invention, it is preferable that the aforementioned inhibitor composition uses a surfactant that further contains a surface coating function for ArF wetting exposure, or includes a step of forming a surface coating before the aforementioned exposure.

[0026] In this invention, even if a surface coating is formed, pattern separation can be performed by dry development, and by using the aforementioned inhibitor composition containing a surfactant, the coating formation steps of the surface coating can be reduced. [Effects of the Invention]

[0027] As described above, according to the pattern forming method of the present invention, since wet development is not performed by alkaline aqueous solution, there is no pattern roughness caused by the swelling effect of the resist during development, nor by the bending / twisting of the resist pattern during drying after development and cleaning. Therefore, a good pattern with less resist line edge roughness can be obtained.

[0028] Furthermore, since dry development does not require siliconization, there is no risk of increased process defects due to the absence of dedicated siliconization equipment, increased complexity of steps, and increased number of steps. Improvements in dimensional uniformity of DRAM products and reductions in pattern defects caused by roughness can be expected. Simple Explanation of the Diagram

[0029] [Figure 1] Figures 1(a) to (g) are explanatory diagrams of an example of the pattern forming method of the present invention (a resist film containing a water-repellent agent for impregnation). [Figure 2] Figures 2(a) to (g) are explanatory diagrams of another example of the pattern forming method of the present invention (forming an impregnated surface coating film). Implementation

[0030] As mentioned above, there is a need to develop a patterning method that uses (meth)acrylic acid polymers that can be used for ArF patterning on the main skeleton and obtains fine patterns with narrow pitch by dry development (dry development) rather than siliconeization.

[0031] Through repeated and in-depth research on the above-mentioned issues, the inventors discovered that the following method can be used in the patterning process to complete the present invention: (A) forming a resist upper film using a resist composition comprising at least a base polymer with a (meth)acrylic acid structure substituted with an acid unstable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent; (B) causing the acid unstable group to detach by post-exposure baking (PEB); (C) volatilizing the detached acid unstable group by high-temperature and short-time hard baking to reduce the carbon content of the exposed part; (D) performing dry development (dry development) with an oxygen-containing gas plasma to obtain the predetermined separation pattern of the aforementioned resist upper film.

[0032] That is, the present invention is a pattern forming method, comprising the following steps: Forming multiple layers on the substrate being processed An ArF excimer positive chemical amplification system inhibitor composition is used to form an inhibitor top film by comprising at least a base polymer having a (meth)acrylic acid structure substituted with an acid-instable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent. The acid-indestructible groups in the exposed portion of the aforementioned resist upper film are removed through exposure and post-exposure baking. A harder baking process, with a higher temperature and shorter duration than the aforementioned post-exposure baking, is performed to cause the aforementioned detached unstable acid groups to volatilize to the outer layer of the aforementioned resist film, creating a difference in the number of carbons between the unexposed and exposed areas. Using an oxygen-containing gaseous plasma, the resist layer film of the aforementioned exposure section is removed by dry development to separate the pattern and... The pattern of the aforementioned upper layer of the resist film is etched and transferred to the aforementioned multilayer layer below.

[0033] The present invention will now be described in detail, but it is not limited thereto.

[0034] [ArF excimer positive chemical amplification system inhibitor composition] The ArF excimer positive chemical amplification inhibitor composition used in the pattern forming method of the present invention may include a base polymer having a (meth)acrylic acid structure substituted with an acid-instable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent. Furthermore, other components may be included as needed. The following describes each component in detail.

[0035] [Basic Polymers] The base polymer contained in the above-mentioned inhibitor composition is a (meth)acrylic acid structure with an acid-indestabilized group substitution. Its structure is not particularly limited, but it is preferable to contain repeating unit a1 represented by the following general formula (a1) or repeating unit a2 represented by the following general formula (a2). [Chemistry 1]

[0036] In the above general formulas (a1) and (a2), RA is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X1 is a single bond, an alkylene group, an alkylene group, or a alkylene group (main chain)-C(=O)-O-X11-, where X11 may contain a 1-10 carbon saturated alkyl group, an alkylene group, an ether bond, an ester bond, or an lactone ring, or an alkylene group or an alkylene group. X2 is a single bond or an alkylene group (main chain)-C(=O)-O-. AL1 and AL2 are independently acid-labile groups.

[0037] The number of carbon atoms of the aforementioned unstable acid groups that are volatilized to the outer layer of the inhibitor film by the aforementioned hard baking is not particularly limited, but it is preferable to be 9 or less, more preferably 4 or more but less than 9, and even more preferably 8 or 9.

[0038] Furthermore, since PEB will detach and the unstable acid group will volatilize due to hard baking, the oxygen number should preferably be 3 or less, and even more preferably 2 or less.

[0039] Furthermore, the fewer hydrogens in the unstable acid groups that volatilize after hard baking, the better, preferably below 22, and more preferably below 18.

[0040] Furthermore, in the above general formula (a2), R11 is a hydrocarbon group with 1 to 20 carbon atoms that may also contain heteroatoms. The aforementioned hydrocarbon group can be saturated or unsaturated, and can be linear, branched, or cyclic. a is an integer from 0 to 4, preferably 0 or 1.

[0041] The structures resulting from changing X1 in the above general formula (a1) can be listed below, but are not limited to these. Furthermore, in the following formula, RA and AL1 are the same as those described above.

[0042] [Chemistry 2]

[0043] [Chemistry 3]

[0044] The basic polymer containing repeating unit a1 decomposes due to the action of acid to produce carboxyl groups and becomes alkali-soluble.

[0045] AL1 and AL2 represent acid-unstable groups, such as groups selected from the following general formulas (L1) to (L4), tertiary hydrocarbon groups with 4 to 9 carbon atoms, preferably 8 or 9, or saturated hydrocarbon groups with 4 to 9 carbon atoms containing carbonyl groups, ether bonds, or ester bonds. [Chemistry 4]

[0046] In the above general formula (L1), RL01 and RL02 are hydrogen atoms or saturated hydrocarbon groups with 1 to 8 carbon atoms. The aforementioned saturated hydrocarbon groups can be linear, branched, or cyclic, and specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, n-octyl, and 2-ethylhexyl; and cyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, and norbenzene.

[0047] In the above general formula (L1), RL03 is a hydrocarbon group with 1 to 8 carbon atoms, and may also contain heteroatoms. The aforementioned hydrocarbon group can be saturated or unsaturated, and can be linear, branched, or cyclic, but preferably a saturated hydrocarbon group. Furthermore, some or all of the hydrogen atoms in the aforementioned saturated hydrocarbon group may be replaced by hydroxyl groups, saturated hydrocarbon oxygen groups, side oxygen groups, amino groups, saturated hydrocarbon amino groups, etc., and part of the -CH2- constituting the aforementioned saturated hydrocarbon group may be replaced by a group containing heteroatoms such as oxygen atoms. Examples of the aforementioned saturated hydrocarbon groups that are the same as those represented by RL01 and RL02 can be listed. Furthermore, examples of substituted saturated hydrocarbon groups include the groups shown below. Additionally, the dashed lines in the formula represent atomic bonds.

[0048] [Chemistry 5]

[0049] Any two of RL01, RL02, and RL03 can bond to each other and form a ring with the carbon atoms they are bonded to, or with carbon atoms and oxygen atoms. When forming a ring, any two of RL01, RL02, and RL03 participating in the ring formation should each have 1 to 8 carbon atoms independently.

[0050] In the above general formula (L2), RL04 is a tertiary hydrocarbon group, or a saturated hydrocarbon group with 4 to 9 carbon atoms containing a carbonyl group, an ether bond, or an ester bond, or a group represented by the above general formula (L1). x is an integer from 0 to 6.

[0051] The tertiary hydrocarbon group represented by RL04 can be branched or cyclic. Specific examples include tertiary butyl, tertiary pentyl, 1,1-diethylpropyl, 2-cyclopentylpropane-2-yl, 2-cyclohexylpropane-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-ethyl-2-cyclopentenyl, and 1-ethyl-2-cyclohexenyl. Saturated hydrocarbon groups containing carbonyl, ether, or ester bonds include 3-side-oxycyclohexyl, 4-methyl-2-side-oxytetrahydropyran-4-yl, and 5-methyl-2-side-oxytetrahydrofuran-5-yl.

[0052] In the above general formula (L3), RL05 is a saturated hydrocarbon group with 1 to 6 carbon atoms that can also be substituted. The aforementioned saturated hydrocarbon groups that can be substituted can be any of the following: linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, tertiary pentyl, n-pentyl, and n-hexyl; cyclic saturated hydrocarbon groups such as cyclopentyl and cyclohexyl; some or all of the hydrogen atoms of these groups can also be substituted by hydroxyl, saturated hydrocarbon oxygen, carboxyl, saturated hydrocarbon carbonyl, side oxygen, amino, saturated hydrocarbon amino, cyano, mercapto, saturated hydrocarbon thio, sulfonic acid, etc.

[0053] Furthermore, in the above general formula (L3), y is 0 or 1, and z is an integer from 0 to 3.

[0054] In the above general formula (L4), RL06 is a saturated hydrocarbon group with 1 or 2 carbon atoms that can also be substituted. Furthermore, in the above general formula (L4), RL07 to RL16 are each independently a hydrogen atom or a hydrocarbon group with 1 or 2 carbon atoms that can also be substituted. The aforementioned hydrocarbon groups can be saturated or unsaturated; examples of such hydrocarbon groups include methyl and ethyl.

[0055] The linear or branched forms of the acid-labile unstable groups represented by the above general formula (L1) can be listed below, but are not limited to these. The dashed lines in the formula represent atomic bonds. [Chemistry 6]

[0056] Among the acid-labile groups represented by the above general formula (L1), cyclic groups can be listed as tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl, 2-methyltetrahydropyran-2-yl, etc.

[0057] The acid-unstable groups represented by the above general formula (L2) can be listed as tertiary butoxycarbonyl, tertiary butoxycarbonylmethyl, tertiary pentoxycarbonyl, tertiary pentoxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl, 1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, 2-tetrahydrofuranyloxycarbonylmethyl, etc.

[0058] The acid-unstable groups represented by the above general formula (L3) can be listed as 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl, 1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-secondary butylcyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl, 3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, 3-ethyl-1-cyclohexen-3-yl, etc.

[0059] The acid unstable group represented by the above general formula (L4) is preferably the group represented by the following general formula (L4-1). [Chemistry 7]

[0060] In the above general formula (L4-1), the dashed lines represent the bond positions and directions. Each RL41 is an independent hydrocarbon group with 1 or 2 carbon atoms. The aforementioned hydrocarbon groups can be saturated or unsaturated. Examples of the aforementioned hydrocarbon groups include methyl and ethyl.

[0061] The acid-instable groups represented by the above general formula (L4) can be listed below, but are not limited to these. Additionally, in the formula, dashed lines represent atomic bonds. [Chemistry 8]

[0062] Furthermore, among the acid-instable groups represented by AL1 and AL2, the tertiary hydrocarbon groups with 4 to 9 carbon atoms and the saturated hydrocarbon groups with 4 to 9 carbon atoms containing carbonyl groups, ether bonds, or ester bonds can each be listed as examples identical to those exemplified in the description of RL04.

[0063] Repeating unit a1 can be listed as shown below, but is not limited to these. Furthermore, in the following formula, RA is the same as described above.

[0064] [Chemistry 9]

[0065] [Chemistry 10]

[0066] [Chemistry 11]

[0067] [Chemistry 12]

[0068] [Chemistry 13]

[0069] Furthermore, these specific examples refer to the case where X1 is a single bond, but cases where X1 is not a single bond can also be combined with the same unstable acid group. Specific examples of cases where X1 is not a single bond have been described above.

[0070] The basic polymer system containing repeating unit a2, like repeating unit a1, decomposes due to the action of acid to produce hydroxyl groups and becomes alkali-soluble.

[0071] Repeating unit a2 may be listed below, but is not limited to these. Furthermore, in the following formula, RA is the same as described above.

[0072] [Chemistry 14]

[0073] [Chemistry 15]

[0074] Furthermore, the aforementioned base polymer can be one that does not have a lactone structure. Even with such a base polymer, exposure and subsequent baking, as well as dry development and subsequent multilayer dry etching transfer to lower layers, can be performed well.

[0075] Furthermore, the etching selectivity ratio of dry development between the unexposed and exposed areas is maximized when 100% of the acid unstable groups are replaced.

[0076] In order to obtain a predetermined dry development selectivity ratio between the unexposed portion and the exposed portion, the aforementioned base polymer preferably has a (meth)acrylic acid structure with a substitution rate (protection rate of the base polymer) of 80% to 100% for the aforementioned acid unstable group.

[0077] That is, the aforementioned base polymer uses a (meth)acrylic acid structure with a substitution rate of 80% to 100% for the aforementioned acid-instable group, and preferably the aforementioned acid-instable group has 4 to 9 carbon atoms.

[0078] The substitution rate of the acid unstable group was determined using NMR.

[0079] Furthermore, the molecular weight Mw of the aforementioned basic polymer is not particularly limited, but it is preferably between 1,000 and 50,000. In addition, the molecular weight Mw refers to the weight-average molecular weight, and is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and polystyrene as a standard substance.

[0080] An example of the synthesis method of the aforementioned basic polymer can be described as a method in which the monomer providing the aforementioned repeating unit is added to an organic solvent with a polymerization initiator and heated to polymerize it.

[0081] Organic solvents used in the aforementioned polymerization reaction may include toluene, benzene, THF, diethyl ether, and dialkylene. Polymerization initiators may include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl 2,2'-azobis(2-methylpropionic acid) ester, benzoyl peroxide, and lauryl peroxide. The reaction temperature should preferably be 50–80°C. The reaction time should preferably be 2–100 hours, preferably 5–20 hours. Acid-labile groups can be used directly from the monomers, or they can be protected or partially protected after polymerization.

[0082] [Photoacid Generator] The aforementioned photoacid generating agents are not particularly limited to compounds that generate acids by irradiation with high-energy rays such as ultraviolet light, far-ultraviolet light, EB, EUV, X-rays, excimer laser light, γ-rays, and synchrotron radiation. Ideal photoacid generating agents include strontium salts, ferrous salts, sulfonyldiazomethane, N-sulfonoxydimethimide, O-arylsulfonyloxime, and O-alkylsulfonyloxime. Examples of such photoacid generating agents include those described in paragraphs

[0102] to

[0113] of Japanese Patent Application Publication No. 2007-145797.

[0083] Preferred photoacid generators include strontium salts represented by the following general formula (2). [Chemistry 16]

[0084] In the above general formula (2), R101, R102, and R103 are each independently a hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. The hydrocarbon groups with 1 to 20 carbon atoms represented by R101, R102, and R103 can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups with 1 to 20 carbon atoms such as methyl, ethyl, propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, tertiary pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norcamphenyl, and tricyclo[5.2.1.02,6]decyl. Cyclic saturated hydrocarbon groups such as adamantyl and adamantylmethyl; aryl groups such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, secondary butylphenyl, tertiary butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, secondary butylnaphthyl, tertiary butylnaphthyl, anthracene; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in these groups may be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms. A portion of the -CH2- group may also be inserted into a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, these groups may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, carbonyl, ether, thioether, ester, sulfonate, carbonate, carbamate, lactone ring, sulopentatyl ring, carboxylic anhydride, or haloalkyl groups.

[0085] Furthermore, R101 and R102 can also bond to each other and form a ring together with the sulfur atoms they are bonded to. In this case, the aforementioned ring should preferably have the structure shown below. In addition, the dashed lines in the formula represent atomic bonds with R103. [Chemistry 17]

[0086] Examples of strontium cations represented by the general formula (2) above include triphenylstrontium, 4-hydroxyphenyl diphenylstrontium, bis(4-hydroxyphenyl)phenylstrontium, tris(4-hydroxyphenyl)strontium, 4-tri-butylphenyl diphenylstrontium, bis(4-tri-butylphenyl)phenylstrontium, tris(4-tri-butylphenyl)strontium, 4-tri-butoxyphenyl diphenylstrontium, bis(4-tri-butoxyphenyl)phenylstrontium, tris(4-tri-butoxyphenyl)strontium, 3- Tri-butoxyphenyl diphenyl strontium, bis(3-tri-butoxyphenyl)phenyl strontium, tris(3-tri-butoxyphenyl) strontium, 3,4-bis(tri-butoxyphenyl)phenyl diphenyl strontium, bis(3,4-bis(tri-butoxyphenyl)phenyl)phenyl strontium, tris(3,4-bis(tri-butoxyphenyl)phenyl) strontium, diphenyl(4-thiophenoxyphenyl) strontium, 4-tri-butoxycarbonylmethyloxyphenyl diphenyl strontium, tris(4-tri-butoxycarbonylmethyl) (4-Tributoxyphenyl) strontium, (4-trimethylbutoxyphenyl)bis(4-dimethylaminophenyl) strontium, trimethyl(4-dimethylaminophenyl) strontium, 2-naphthyldiphenyl strontium, (4-hydroxy-3,5-dimethylphenyl) diphenyl strontium, (4-n-hexyloxy-3,5-dimethylphenyl) diphenyl strontium, dimethyl(2-naphthyl) strontium, 4-hydroxyphenyl dimethyl strontium, 4-methoxyphenyl dimethyl strontium, trimethyl strontium, 2-side-oxycyclohexyl ... Cationic compounds include hexylmethyl strontium, trinaphthyl strontium, tribenzyl strontium, diphenylmethyl strontium, dimethylphenyl strontium, 2-sideoxy-2-phenylethylthiacyclopentanium, diphenyl-2-thienyl strontium, 4-n-butoxynaphthyl-1-thiacyclopentanium, 2-n-butoxynaphthyl-1-thiacyclopentanium, 4-methoxynaphthyl-1-thiacyclopentanium, and 2-methoxynaphthyl-1-thiacyclopentanium.

[0087] Furthermore, the strontium cations of the strontium salts represented by the above general formula (2) can be represented by the following formulas. In addition, in the following formulas, Me is a methyl group. [Chemistry 18]

[0088] Among these, triphenyl strontium, 4-tri-butylphenyl diphenyl strontium, 4-tri-butoxyphenyl diphenyl strontium, tris(4-tri-butylphenyl) strontium, tris(4-tri-butoxyphenyl) strontium, dimethylphenyl strontium, etc.

[0089] In the above general formula (2), Xa- is an anion represented by any of the following general formulas (2A) to (2D). [Chemistry 19]

[0090] In the above general formula (2A), Rfa is a fluorine atom, or a hydrocarbon group with 1 to 40 carbon atoms that may also contain heteroatoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic.

[0091] The anion represented by the above general formula (2A) is preferably represented by the following general formula (2A'). [Chemistry 20]

[0092] In the above general formula (2A'), RHF is a hydrogen atom or a trifluoromethyl group. R111 is a hydrocarbon group with 1 to 30 carbon atoms, which may also contain heteroatoms. The aforementioned heteroatoms are preferably oxygen, nitrogen, sulfur, or halogen atoms, with oxygen atoms being more preferred. Considering the viewpoint of obtaining high resolution in forming fine patterns, the aforementioned hydrocarbon group is particularly preferably one with 6 to 30 carbon atoms.

[0093] The hydrocarbon group represented by R111 can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups with 1 to 30 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecanyl, and eicosyl; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norcamphenyl, norcamphenylmethyl, tricyclodecyl, tetracyclododecyl, tetracyclododecylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbon groups with 2 to 30 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups with 6 to 30 carbon atoms, such as phenyl, 1-naphthyl, and 2-naphthyl; aryl groups with 7 to 30 carbon atoms, such as benzyl and diphenylmethyl; and groups obtained by combining these.

[0094] Furthermore, some or all of the hydrogen atoms in these groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms. Similarly, some of the carbon atoms in these groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, and nitrogen atoms. As a result, they may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether, ester, sulfonate, carbonate, lactone ring, sulopentalide ring, carboxylic anhydride, or haloalkyl groups. Examples of hydrocarbon groups containing heteroatoms include tetrahydrofuranyl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetaminomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-sideoxypropyl, 4-sideoxy-1-adamantyl, and 3-sideoxycyclohexyl.

[0095] Synthesizing strontium salts having anions represented by the above general formula (2A') is detailed in Japanese Patent Application Publication Nos. 2007-145797, 2008-106045, 2009-007327, and 2009-258695.

[0096] The anions represented by the above general formula (2A) may include nonafluorobutanesulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

[0251] of Japanese Patent Application Publication No. 2012-189977, partially fluorinated sulfonates described in paragraphs

[0261] to

[0265] of Japanese Patent Application Publication No. 2013-101271, and those shown below, but are not limited to these. In addition, in the following formula, Ac is acetyl.

[0097] [Chemistry 21]

[0098] [Chemistry 22]

[0099] [Chemistry 23]

[0100] In the above general formula (2B), Rfb1 and Rfb2 are each independently a fluorine atom, or may contain heteroatoms and are hydrocarbon groups with 1 to 40 carbon atoms. The aforementioned hydrocarbon groups may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples can be given as those illustrated in the above general formula (2A') for the hydrocarbon group represented by R111. Rfb1 and Rfb2 are preferably fluorine atoms or linear fluorinated alkyl groups with 1 to 4 carbon atoms. Furthermore, Rfb1 and Rfb2 may also be bonded to each other and form a ring together with the group they are bonded to (-CF2-SO2-N--SO2-CF2-). In this case, the group obtained by the mutual bonding of Rfb1 and Rfb2 is preferably fluorinated ethyl or fluorinated propyl.

[0101] In the above general formula (2C), Rfc1, Rfc2, and Rfc3 are each independently a fluorine atom, or may contain heteroatoms and are hydrocarbon groups with 1 to 40 carbon atoms. The aforementioned hydrocarbon groups may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples can be given as those illustrated in the above general formula (2A') for the hydrocarbon group represented by R111. Rfc1, Rfc2, and Rfc3 are preferably fluorine atoms or linear fluorinated alkyl groups with 1 to 4 carbon atoms. Furthermore, Rfc1 and Rfc2 may also be mutually bonded and form a ring together with the group they are bonded to (-CF2-SO2-C--SO2-CF2-), in which case the group obtained by the mutual bonding of Rfc1 and Rfc2 is preferably fluorinated ethyl or fluorinated propyl.

[0102] In the above general formula (2D), Rfd is a hydrocarbon group with 1 to 40 carbon atoms, which may also contain heteroatoms. The aforementioned hydrocarbon group can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples can be given as those illustrated in the above general formula (2A') for the hydrocarbon group represented by R111.

[0103] The synthesis of strontium salts having anions represented by the above general formula (2D) is detailed in Japanese Patent Application Publication No. 2010-215608.

[0104] The anions represented by the above general formula (2D) can be listed below, but are not limited to these.

[0105] [Chemistry 24]

[0106] [Chemistry 25]

[0107] Furthermore, the photoacid generator containing the anion represented by the above general formula (2D) does not have a fluorine atom at the α-position of the sulfonic acid group, but has two trifluoromethyl groups at the β-position, thus possessing sufficient acidity to cleave the acid-instable groups in the base polymer. Therefore, it can be used as a photoacid generator.

[0108] Furthermore, the photoacid generator should also be represented by the following general formula (3). [Chemistry 26]

[0109] In the above general formula (3), R201 and R202 are each independently a hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. R203 is an extended hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. Furthermore, any two of R201, R202, and R203 may bond to each other and form a ring together with the sulfur atoms they are bonded to. In this case, the aforementioned ring can be the same as the one exemplified in the description of the above general formula (2) in which R101 and R102 can bond to each other and form a ring together with the sulfur atoms they are bonded to.

[0110] The hydrocarbon groups represented by R201 and R202 can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups with 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, n-pentyl, tertiary pentyl, n-hexyl, n-octyl, and 2-ethylhexyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclohexylmethyl, cyclohexylethyl, norbornel, oxanorbornel, tricyclo[5.2.1.02,6]decyl, and adamantyl; phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, secondary butylphenyl, tertiary butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, secondary butylnaphthyl, and tertiary butylnaphthyl; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in these groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms. Similarly, a portion of the -CH2- group can be replaced by groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, these groups may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether, ester, sulfonate, carbonate, lactone, sulopentalide, carboxylic anhydride, or haloalkyl groups. Among these, R201 and R202 are preferably aryl groups in which hydrogen atoms can also be substituted.

[0111] R203 indicates that the alkyl group can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, and heptadecane-1,17-diyl. Dialkyl groups with 1 to 20 carbon atoms; cyclopentanediyl, cyclohexanediyl, norcamphenediyl, adamantanediyl, and other cyclic saturated hydrocarbon groups with 3 to 20 carbon atoms; phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, secondary butylphenyl, tertiary butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, secondary butylnaphthyl, tertiary butylnaphthyl, and other aryl groups with 6 to 20 carbon atoms; and other groups obtained by combining these. Furthermore, some or all of the hydrogen atoms in these groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms. Similarly, a portion of the -CH2- group can be replaced by groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, these groups may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether, ester, sulfonate, carbonate, lactone, sulopentalide, carboxylic anhydride, or haloalkyl groups. Among these, R203 is preferably an aryl group in which hydrogen atoms can also be substituted.

[0112] In the above general formula (3), G is a single bond or a hydrocarbon group with 1 to 20 carbon atoms that may contain heteroatoms. The hydrocarbon group represented by G can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples can be listed as those exemplified with respect to the hydrocarbon group represented by R203. Furthermore, some or all of the hydrogen atoms in such groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- in such groups can also be replaced by groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, it may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether bond, ester bond, sulfonate bond, carbonate bond, lactone ring, sulopentalide ring, carboxylic anhydride, or haloalkyl. Among these, G is preferably a methylene group, or a methylene group in which the hydrogen atom is replaced by a fluorine atom or a trifluoromethyl group.

[0113] In the above general formula (3), Lx is a divalent linker. Examples of such linkers include ether bonds, ester bonds, thioether bonds, sulfinic acid ester bonds, sulfonate bonds, carbonate bonds, and carbamate bonds.

[0114] The photoacid generator represented by the above general formula (3) can be exemplified by the same photoacid generator represented by formula (3) in Japanese Patent Application Publication No. 2018-062503.

[0115] In the above-mentioned inhibitor composition, the content of the photoacid generating agent is not particularly limited, but it is preferably 0 to 40 parts by weight relative to 80 parts by weight of the base polymer, more preferably 0.1 to 40 parts by weight, and even more preferably 0.1 to 20 parts by weight. Within this range, the resolution is good. One photoacid generating agent can be used alone, or two or more can be used in combination.

[0116] [Quenching Agent] Regarding the acid diffusion control agent, the aforementioned inhibitor composition includes a quencher as an essential component. Examples of quenchers include amine compounds and onium salt compounds. Examples of amine compounds include first-, second-, or third-order amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Application Publication No. 2008-111103, particularly amine compounds having hydroxyl groups, ether bonds, ester bonds, lactone rings, cyano groups, or sulfonate bonds. Furthermore, compounds described in Japanese Patent No. 3790649, such as those formed by protecting first- or second-order amines with carbamate groups, can also be cited. Examples of onium salt compounds include compounds described in the aforementioned Patent Document 1 and Japanese Patent Application Publication No. 2003-005376.

[0117] Alternatively, strontium sulfonate salts with nitrogen-containing substituents can be used as quenchers. Such compounds function as quenchers in the unexposed areas, but lose their quenching ability in the exposed areas due to neutralization with the acid they generate, thus functioning as so-called photodegrading bases. By using photodegrading bases, the contrast between the exposed and unexposed areas can be enhanced. Examples of photodegrading bases can be found in Japanese Patent Application Publication Nos. 2009-109595 and 2012-046501.

[0118] The content of the quencher in the above-mentioned inhibitor composition is not particularly limited, but it is preferably 0.001 to 12 parts by weight, and more preferably 0.01 to 8 parts by weight, relative to 80 parts by weight of the base polymer. The quencher can be used alone or in combination of two or more.

[0119] Furthermore, there are no particular limitations on the photoacid generating agent and quenching agent contained in the above-mentioned inhibitor composition. For example, the one described in Japanese Patent Application Publication No. 2010-215608 can be cited as an example.

[0120] [Organic solvents] There are no particular limitations on the organic solvent, provided that it has sufficient solubility for the components contained in the above-mentioned inhibitor composition and good film-forming properties. Examples of such organic solvents include cellosolve acetate and other cellosolve-based solvents, propylene glycol monomethyl ether and other propylene glycol alkyl ether solvents, propylene glycol monomethyl ether acetate and other propylene glycol alkyl ether acetate solvents, ester solvents such as butyl acetate and ethyl lactate, alcohol solvents such as isopropanol, ketone solvents such as cyclohexanone and methyl isobutyl ketone, ether solvents such as methyl phenyl ether, highly polar solvents such as N-methylpyrrolidone, and mixed solvents thereof.

[0121] [Surfactants] To reduce the surface coating formation steps during ArF immersion exposure, a water-repellent component (surfactant) exhibiting surface coating function can be added to the resist composition as needed. The water-repellent layer with the aforementioned surface coating function is formed on the upper resist film with a uniform film thickness during coating. After exposure and post-exposure baking, the water-repellent layer remains uniformly on the upper resist film. However, the composition of the water-repellent layer itself does not change before exposure and after post-exposure baking, thus it is easily removed during the dry development separation step when separating the exposed and unexposed portions.

[0122] Furthermore, the surfactant should preferably be a surfactant that is insoluble or sparingly soluble in water and alkaline developing solution, or a surfactant that is insoluble or sparingly soluble in water but soluble in alkaline developing solution. Such surfactants can be referred to in Japanese Patent Application Publication Nos. 2007-297590, 2010-215608, and 2011-016746.

[0123] The aforementioned surfactants that are insoluble or poorly soluble in water and alkaline developing solutions include nonionic surfactants such as polyoxyethylene alkyl ethers (e.g., polyoxyethylene oil ethers), polyoxyethylene alkyl aromatic ethers (e.g., polyoxyethylene nonylphenol ethers), polyoxyethylene polyoxypropylene block copolymers, sorbitan fatty acid esters (e.g., sorbitan monostearate), and polyoxyethylene fatty acid esters (e.g., polyoxyethylene sorbitan monolaurate). Among the surfactants described in the aforementioned announcement, FC-4430 (manufactured by 3M Corporation), SURFLON (registered trademark) S-381 (manufactured by AGC SEIMI CHEMICAL), OLFINE (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC SEIMI CHEMICAL), and oxocyclic butane ring-opening polymers represented by the following general formula (surf-1) are preferred. [Chemistry 27]

[0124] Here, R, Rf, A, B, C, m, and n are irrelevant to the aforementioned descriptions and apply only to the general formula (surf-1). R is an aliphatic group with 2 to 5 carbon atoms, ranging from 2 to 4 valences. Examples of the aforementioned aliphatic groups with 2 valences include ethyl, 1,4-butyl, 1,2-propyl, 2,2-dimethyl-1,3-propyl, and 1,5-pentyl, while examples of those with 3 or 4 valences include the following. In the formula, the dashed lines represent atomic bonds, each derived from a substructure of glycerol, trimethylolethane, trimethylolpropane, or neopentyl tertrol. [Chemistry 28]

[0125] Among these, 1,4-endobutyl, 2,2-dimethyl-1,3-endopropyl, etc. are preferred.

[0126] Rf is trifluoromethyl or pentafluoroethyl, preferably trifluoromethyl. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m is the valence of R, which is an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. Furthermore, the arrangement of the constituent units in the above general formula (surf-1) is not specified; they can be block-bonded or randomly bonded. For details on the manufacture of surfactants in partially fluorinated oxyheterocyclic butane ring-opening polymer systems, please refer to the specification of US Patent No. 5,650,483, etc.

[0127] Surfactants that are insoluble or sparingly soluble in water but soluble in alkaline developing solutions can reduce water penetration and leaching during ArF immersion exposure when no resist protective film is used. This is useful for inhibiting the leaching of water-soluble components from the resist upper film and reducing damage to the exposure equipment. Furthermore, they are soluble in alkaline developing solutions after exposure and post-exposure baking (PEB), making them unlikely to be foreign matter causing defects. Such surfactants, being insoluble or sparingly soluble in water but soluble in alkaline developing solutions, are polymer-type surfactants, also known as hydrophobic resins, and are particularly suitable for those with high water-repellent properties and improved hydrophobicity.

[0128] Such polymeric surfactants may include at least one of the repeating units represented by any of the following general formulas (4A) to (4E). [Chemistry 29]

[0129] In the above general formulas (4A) to (4E), RB is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. W1 is -CH2-, -CH2CH2-, -O-, or two separate -H groups. Rs1 is each independently a hydrogen atom or a hydrocarbon group with 1 to 10 carbon atoms. Rs2 is a single bond or a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms. Rs3 is each independently a hydrogen atom, a hydrocarbon group or a fluorinated hydrocarbon group with 1 to 15 carbon atoms, or an acid-unstable group. When Rs3 is a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between carbon-carbon bonds. Rs4 is a (u+1) valence hydrocarbon group or a fluorinated hydrocarbon group with 1 to 20 carbon atoms. u is an integer from 1 to 3. Rs5 is each independently a hydrogen atom or a group represented by -C(=O)-O-Rs7. Rs7 is a fluorinated hydrocarbon group with 1 to 20 carbon atoms. Rs6 is a hydrocarbon group or fluorinated hydrocarbon group with 1 to 15 carbon atoms, and an ether bond or carbonyl group may be inserted between its carbon-carbon bonds.

[0130] The hydrocarbon group represented by Rs1 can be any of the following: linear, branched, or cyclic. Specific examples include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, secondary butyl, tertiary butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, adamantyl, norbornel, etc. Among these, it is preferable that the hydrocarbon group has 1 to 6 carbon atoms.

[0131] Rs2 represents an enyl group that can be linear, branched, or cyclic. Specific examples include methylene, enylethyl, enylpropyl, enylbutyl, and enylpentyl.

[0132] The hydrocarbon groups represented by Rs3 and Rs6 can be linear, branched, or cyclic, and specific examples include alkyl, alkenyl, and ynyl groups, but preferably alkyl. Besides those exemplified by the hydrocarbon group represented by Rs1, the aforementioned alkyl groups can also include undecyl, dodecyl, tridecyl, tetradecyl, and pentadecyl groups. The fluorinated hydrocarbon groups represented by Rs3 and Rs6 can be groups in which some or all of the hydrogen atoms of the carbon atom bonded to the aforementioned hydrocarbon group are replaced by fluorine atoms. As mentioned above, ether bonds or carbonyl groups can also be inserted between these carbon-carbon bonds.

[0133] The acid-instable groups represented by Rs3 can include those represented by the general formulas (L1) to (L4) above, tertiary hydrocarbon groups with 4 to 20 carbons, preferably 4 to 15, trialkylsilyl groups where each alkyl group has 1 to 6 carbons, and alkyl groups with 4 to 20 carbons, etc.

[0134] Rs4 represents a (u+1) valence hydrocarbon group or fluorinated hydrocarbon group that can be straight-chain, branched, or cyclic. Specific examples can be listed as groups obtained by further removing u hydrogen atoms from the aforementioned hydrocarbon group or fluorinated hydrocarbon group.

[0135] Rs7 indicates that the fluorinated hydrocarbon group can be linear, branched, or cyclic. Specifically, examples include hydrocarbon groups in which some or all of the hydrogen atoms are replaced by fluorine atoms. Examples include trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoro-1-propyl, 3,3,3-trifluoro-2-propyl, 2,2,3,3-tetrafluoropropyl, 1,1,1,3,3,3-hexafluoroisopropyl, 2,2,3,3,4,4,4-heptafluorobutyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 2,2,3,3,4,4,5,5,6,6,7,7-dodecylheptyl, 2-(perfluorobutyl)ethyl, 2-(perfluorohexyl)ethyl, 2-(perfluorooctyl)ethyl, 2-(perfluorodecyl)ethyl, etc.

[0136] The repeating units in any of the above general formulas (4A) to (4E) can be listed as shown below, but are not limited to these. In addition, RB in the following formula is the same as above.

[0137] [Chemistry 30]

[0138] [Chemistry 31]

[0139] [Chemistry 32]

[0140] The aforementioned polymeric surfactants may further include repeating units other than those represented by the repeating units of the above general formulas (4A) to (4E). Other repeating units may be those obtained from methacrylic acid, α-trifluoromethacrylic acid derivatives, etc. In the polymeric surfactant, the content of the repeating units represented by the above general formulas (4A) to (4E) is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of all repeating units.

[0141] The molecular weight (Mw) of the aforementioned 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 rare.

[0142] The following methods can be used to synthesize the above-mentioned polymeric surfactants: Monomers containing unsaturated bonds, given repeating units represented by the above general formulas (4A) to (4E) and, if necessary, other repeating units, are polymerized in an organic solvent with a free radical initiator and heated. Examples of organic solvents used in polymerization include toluene, benzene, THF, diethyl ether, and dialkylene. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl 2,2'-azobis(2-methylpropionic acid) ester, benzoyl peroxide, and lauryl peroxide. The reaction temperature should preferably be 50–100°C. The reaction time should preferably be 4–24 hours. Acid-labile groups can be directly used from monomers that have already been introduced, or they can be protected or partially protected after polymerization.

[0143] When synthesizing the above-mentioned polymeric surfactants, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol can be used to adjust the molecular weight. In this case, the amount of such chain transfer agent added relative to the total moles of the monomers being polymerized should preferably be 0.01 to 10 moles.

[0144] The surfactants mentioned above that are insoluble or sparingly soluble in water but soluble in alkaline developing solutions can also be referenced in Japanese Patent Application Publication Nos. 2008-122932, 2010-134012, 2010-107695, 2009-276363, 2009-192784, 2009-191151, 2009-098638, 2010-250105, and 2011-042789.

[0145] The content of the surfactant relative to 80 parts by weight of the base polymer is preferably 0 to 20 parts by weight. When surfactant is included, the lower limit is preferably 0.001 parts by weight, more preferably 0.01 parts by weight. On the other hand, the upper limit is preferably 15 parts by weight, more preferably 10 parts by weight. One type of surfactant may be used alone, or two or more may be used in combination.

[0146] [Pattern Formation Method] Furthermore, regarding patterning methods, the aforementioned resist composition is formed by coating a multilayer substrate containing Si elements, followed by ArF immersion exposure and post-exposure baking. Then, dry development (dry development) is performed using oxygen-containing gas plasma to separate the resist pattern. Next, the resist pattern is transferred to the substrate under dry etching conditions containing fluorine gas.

[0147] That is, in this invention, a pattern forming method is provided, comprising the following steps: Forming multiple layers on the substrate being processed An ArF excimer positive chemical amplification system inhibitor composition is used to form an inhibitor top film by comprising at least a base polymer having a (meth)acrylic acid structure substituted with an acid-instable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent. The acid-indestructible groups in the exposed portion of the aforementioned resist upper film are removed through exposure and post-exposure baking. A harder baking process, with a higher temperature and shorter duration than the aforementioned post-exposure baking, is performed to cause the aforementioned detached unstable acid groups to volatilize to the outer layer of the aforementioned resist film, creating a difference in the number of carbons between the unexposed and exposed areas. Using an oxygen-containing gaseous plasma, the resist layer film of the aforementioned exposure section is removed by dry development to separate the pattern and... The pattern of the aforementioned upper layer of the resist film is etched and transferred to the aforementioned multilayer layer below.

[0148] The substrate used in the pattern forming method of the present invention is not particularly limited; for example, a substrate on which the film to be processed is formed can be used. Examples of the film to be processed include silicon oxide films.

[0149] There are no particular limitations on the number of layers formed on the substrate as long as they consist of two or more layers. For example, the lower layer of the multilayer formed on the substrate can be a coated carbon film. For example, the intermediate layer formed on the lower layer can be a coated Si-containing antireflective film.

[0150] The resist composition that forms the upper resist film can be listed above. Furthermore, there are no particular limitations on the method for forming the upper resist film; known methods can be used.

[0151] There are no particular limitations on the exposure conditions for the above-mentioned resist upper film. For example, when forming fine lines and spacing patterns, dipole illumination conditions can be used to form a predetermined pattern.

[0152] To achieve the desired deprotection reaction of the acid unstable groups with a high protection rate of 80% to 100%, and the desired volatilization of the deprotected acid unstable groups, the process is divided into a first low-temperature baking (PEB) and a second high-temperature baking (hard baking, which determines the quality of the dry-developed pattern). The first low-temperature baking, i.e., the post-exposure baking described above, should preferably be performed for 40 to 120 seconds, preferably 60 to 120 seconds, while the second high-temperature baking, i.e., the hard baking described above, should preferably be performed for less than 40 seconds.

[0153] The first low-temperature baking should be between 80℃ and 120℃. The second high-temperature baking should be performed at a higher temperature than the first low-temperature baking. Furthermore, the second high-temperature baking should preferably be above 130℃, and more preferably above 150℃.

[0154] That is, the aforementioned exposure followed by baking should be performed at 80℃~120℃ for 40 seconds~120 seconds, and the aforementioned hard baking should be performed at 130℃ or above for less than 40 seconds. Furthermore, the aforementioned hard baking should be performed at 150℃ or above for less than 40 seconds.

[0155] Regardless of whether the deprotection reaction occurs at low temperature or high temperature with PEB, any acid-labile group that volatilizes to the outer layer of the inhibitor film through the aforementioned hard baking process can be used. In particular, the aforementioned acid-labile group preferably has 4 to 9 carbon atoms. Furthermore, acid-labile groups with 4 to 9 carbon atoms preferably have a cyclic skeleton.

[0156] Furthermore, the basic polymers with acid-instable groups that are substituted by PEB and volatilize upon hard baking are not limited to a single type; a variety of acid-instable group-substituted basic polymers can be used.

[0157] Furthermore, it is advisable to use a surfactant containing a surface coating function that enables ArF wetting exposure for the aforementioned inhibitor composition, or to include a step of forming a surface coating before the aforementioned exposure.

[0158] As for dry development, there are no particular limitations as long as an oxygen-containing gas plasma is used.

[0159] There are no particular limitations on the method of etching and transferring the pattern of the upper resist film to the lower layer of the multilayer film, and known methods can be used.

[0160] FIG1 illustrates an example of the pattern formation method of the present invention. On a wafer substrate 1, on which a processing film 2 is formed, a multilayer comprising a coated carbon film 3 and a coated Si-containing antireflective film 4 is formed. An ArF positive chemical amplification resist composition is then used to form an ArF positive chemical amplification resist top layer film 5 (FIG. 1(a)). Next, the ArF positive chemical amplification resist top layer film is exposed using a photomask 6 and ArF exposure light 7 (FIG. 1(b)). Next, PEB is performed to form an exposed resist portion 5a with deprotected acid-instable groups on the ArF positive chemical amplification resist top layer film (FIG. 1(c)). Next, hard baking is performed to evaporate the acid-instable groups from the exposed resist portion 5a (FIG. 1(d)). Next, the exposed resist portion is removed by dry development using an oxygen-containing gas plasma to form a resist pattern 5b (FIG. 1(e)). Next, using the resist pattern 5b as a mask, the pattern is transferred to a coated Si-containing antireflective film to form a coated Si-containing antireflective film pattern 4a (Fig. 1(f)). Then, using the coated Si-containing antireflective film pattern 4a as a mask, the pattern is transferred to a coated carbon film to form a coated carbon film pattern 3a (Fig. 1(g)).

[0161] Figure 2 illustrates another example of the pattern formation method of the present invention. On a wafer substrate 21 on which a processing film 22 is formed, a multilayer comprising a coated carbon film 23 and a coated Si-containing antireflective film 24 is formed. An ArF positive chemical amplification resist composition is used to form an ArF positive chemical amplification resist upper layer film 25 thereon, and a wetting surface coating film 28 is formed thereon (Figure 2(a)). Next, the ArF positive chemical amplification resist upper layer film is exposed using a photomask 26 and ArF exposure light 27 (Figure 2(b)). Next, PEB is performed to form an acid-instable group deprotected resist exposure portion 25a on the ArF positive chemical amplification resist upper layer film (Figure 2(c)). Next, hard baking is performed to cause the acid-instable groups to evaporate from the acid-instable group deprotected resist exposure portion 25a located beneath the wetting surface coating film 28a (Figure 2(d)). Next, the resist exposed area is removed by dry development using an oxygen-containing gas plasma to form a resist pattern 25b (Fig. 2(e)). Then, using the resist pattern 25b as a mask, the pattern is transferred to a coated Si-containing antireflective film to form a coated Si-containing antireflective film pattern 24a (Fig. 2(f)). Next, using the coated Si-containing antireflective film pattern 24a as a mask, the pattern is transferred to a coated carbon film to form a coated carbon film pattern 23a (Fig. 2(g)). [Example]

[0162] The present invention will now be described in detail using examples and comparative examples, but the present invention is not limited thereto.

[0163] (Preparation of inhibitor composition) Following a predetermined synthesis method, a base polymer with a predetermined number of carbon atoms and substitution rate was prepared. An acid generator, a quencher, and a water-repellent agent (surfactant) for wetting were dissolved in PGMEA organic solvent to prepare a solution. The solution was then filtered through a 0.2 μm Teflon (registered trademark) filter membrane to prepare inhibitor compositions R1~R16, R21~R2C, R31, R32, and R41~R48 (composed with 10%, 30%, 80%, and 100% protection rates for each acid unstable group with 4, 5, 8, and 9 carbon atoms; compositions with 10% and 90% protection rates for each acid unstable group with 4, 5, 8, 9, and 10 carbon atoms; a composition with 100% protection rate for each acid unstable group with 9 carbon atoms; and compositions with 100%, 90%, 80%, 70%, 60%, 50%, 40%, and 10% protection rates for each acid unstable group with 9 carbon atoms). In addition, the protection rate is a value obtained using NMR. The structures of each repeating unit of AL1 to AL5, the photoacid generator AG1, the quencher Q1, and the water-repellent agent PF1 are described below.

[0164] [Chemistry 33]

[0165] (Evaluation of resist pattern formation 1) Table 1 is a list of evaluation samples used to investigate the dependence of protection rate (substitution rate) of acid unstable groups (inhibitor pattern formation evaluation 1).

[0166] [Table 1] Sample Name Basic polymers 100 copies Photoacid generator 10 copies Quenching agent 5 copies Water-repellent 5 copies solvent PGMEA% Acid unstable group Protection rate % type type R1 AL1 10 AG1 Q1 PF1 100 R2 AL1 30 AG1 Q1 PF1 100 R3 AL1 80 AG1 Q1 PF1 100 R4 AL1 100 AG1 Q1 PF1 100 R5 AL2 10 AG1 Q1 PF1 100 R6 AL2 30 AG1 Q1 PF1 100 R7 AL2 80 AG1 Q1 PF1 100 R8 AL2 100 AG1 Q1 PF1 100 R9 AL3 10 AG1 Q1 PF1 100 R10 AL3 30 AG1 Q1 PF1 100 R11 AL3 80 AG1 Q1 PF1 100 R12 AL3 100 AG1 Q1 PF1 100 R13 AL4 10 AG1 Q1 PF1 100 R14 AL4 30 AG1 Q1 PF1 100 R15 AL4 80 AG1 Q1 PF1 100 R16 AL4 100 AG1 Q1 PF1 100

[0167] First, a multilayer film was formed on the substrate (SiO film) of the wafer (coated carbon film was processed at 250°C for 60 seconds to form a 54nm coating, and Si-containing antireflective film was processed at 220°C for 60 seconds to form an 18nm coating). On top of this, the resist compositions shown in Table 1 were coated by spin coating and pre-baking. The pre-baking was performed at 120°C for 60 seconds to obtain sample wafers with a resist film thickness of 130nm.

[0168] Next, using an ArF immersion exposure machine with a lens numerical aperture of 1.35 NA, the line and spacing pattern formed on the binary photomask with a half-pitch of 40 nm was exposed under a fixed exposure condition of 25 mJ / cm². Then, each exposed wafer was subjected to PEB (Post Exposure Bake) treatment at 90°C for 90 seconds on a heated plate. Following this, a hard bake was performed at 150°C for 30 seconds. The results of measuring the step difference between the exposed and unexposed areas of each sample after hard baking using an AFM (Atomic Force Microscope) are summarized in Table 2.

[0169] [Table 2] Basic polymers (Sample Name) Film loss in the exposed area after hard baking (nm) (Initial film thickness 130nm) AL1 Carbon number 4 AL2 Carbon number 5 AL3 Carbon number 8 AL4 Carbon number 9 Protection rate 10% 7.1 (R1) 9.0 (R5) 13.4 (R9) 14.7 (R13) Protection rate 30% 19.0 (R2) 23.6 (R6) 32.9 (R10) 35.4 (R14) Protection rate 80% 40.2 (R3) 47.4 (R7) 60.2 (R11) 63.3 (R15) 100% protection rate 46.3 (R4) 53.9 (R8) 66.8 (R12) 69.9 (R16)

[0170] In the resistive compositions (R1 to R16) of base polymers protected (substituted) with 4 to 9 carbon atoms, film loss in the exposed areas after hard baking was confirmed. The higher the carbon number, the greater the film loss in the exposed areas after hard baking.

[0171] Next, the evaluation samples in Table 2 were subjected to dry development, and the residual resist film in the unexposed areas after resist pattern separation was measured. The results are shown in Table 3. Furthermore, the aforementioned dry development conditions are as described below. Chamber pressure: 30mT RF power output (upper section): 200W RF power at the bottom: 100W O2 gas flow rate: 20 sccm N2 gas flow rate: 290 sccm Etching time: 6 seconds

[0172] [Table 3] Basic polymers (Sample Name) The residual film thickness in the unexposed area after dry development is in nm. (Initial film thickness 130nm) Carbon number 4 AL1 Carbon number 5 AL2 Carbon number 8 AL3 Carbon number 9 AL4 Protection rate 10% 16.5 (R1) 20.1 (R5) 31.2 (R9) 34.7 (R13) Protection rate 30% 28.6 (R2) 34.0 (R6) 60.6 (R10) 65.1 (R14) Protection rate 80% 64.7 (R3) 71.6 (R7) 86.8 (R11) 90.4 (R15) 100% protection rate 70.9 (R4) 77.5 (R8) 91.6 (R12) 95.0 (R16)

[0173] Any of the evaluation samples R1 to R16 with carbon numbers of 4 to 9 and a protection rate of 10% to 100% can ensure resist residue in the unexposed areas after dry development. The higher the carbon number and the higher the protection rate, the larger the residue in the unexposed areas.

[0174] (Evaluation of resist pattern formation 2) Table 4 shows the results of investigating the effects of non-volatile protecting groups in the base polymer on film loss in the exposed section after hard baking and residual film thickness after dry development. Structures with 4-9 carbon atoms were used as acid-labile unstable groups that would volatilize during hard baking, while structures with 10 carbon atoms and high-temperature activation energy were used as structures that would not volatilize during hard baking. Furthermore, the protection rate (substitution rate) of the base polymer was set to 10%-90%.

[0175] [Table 4] Sample Name Protection rate of acid unstable groups (types) % Photoacid generator AG 1 copy Quenching agent Q1 Water-repellent PF 1 solvent PGMEA% AL1 AL2 AL3 AL4 AL5 R21 90 - - - 10 10 8 5 100 R22 10 - - - 10 10 8 5 100 R23 10 - - 90 10 8 5 100 R24 - 90 - - 10 10 8 5 100 R25 - 10 - - 10 10 8 5 100 R26 - 10 - - 90 10 8 5 100 R27 - - 90 - 10 10 8 5 100 R28 - - 10 - 10 10 8 5 100 R29 - - 10 - 90 10 8 5 100 R2A - - 90 10 10 8 5 100 R2B - - 10 10 10 8 5 100 R2C - - 10 90 10 8 5 100

[0176] First, multiple layers of film are formed on the substrate (SiO film) of the wafer (coated carbon film is processed at 250°C for 60 seconds to form a 54nm coating, and Si-containing antireflective film is processed at 220°C for 60 seconds to form an 18nm coating). On top of these layers, resist compositions as shown in Table 4 are coated using spin coating and pre-baking. Pre-baking is performed at 120°C for 60 seconds to obtain sample wafers with a resist film thickness of 130nm.

[0177] Next, using an ArF immersion exposure machine with a lens digital aperture of 1.35 NA, the line and spacing pattern formed on the binary photomask with a half pitch of 40 nm was exposed under fixed exposure conditions of 25 mJ / cm². Then, each exposed wafer was subjected to PEB (Post Exposure Bake) treatment at 90°C for 90 seconds on a heated plate, followed by hard baking at 150°C for 30 seconds.

[0178] The upper section of Table 5 shows the results of measuring the step difference between the exposed and unexposed portions of each sample after hard baking using AFM (Atomic Force Microscope). The lower section of the same table then records the results of measuring the residual film thickness of the unexposed portion after dry development under oxygen-containing gas plasma conditions. Furthermore, the aforementioned dry development conditions are described below. Chamber pressure: 30mT RF power output (upper section): 200W RF power at the bottom: 100W O2 gas flow rate: 20 sccm N2 gas flow rate: 290 sccm Etching time: 6 seconds

[0179] [Table 5] Acid unstable group Acid unstable fixed base Carbon number 4 AL1 Carbon number 5 AL2 Carbon number 8 AL3 Carbon number 9 AL4 10 carbons AL5 R21 39.4 R24 46.6 R27 59.3 R2A 62.5 66.1 72.1 86.2 89.7 R22 6.2 R25 7.9 R28 11.8 R2B 12.9 28.4 30.7 38.0 40.5 R23 3.1 R26 3.9 R29 6.0 R2C 6.6 11.8 12.7 15.7 16.9

[0180] Any evaluation sample with carbon numbers 4-9 (R21-R2C) of the acid unstable group can be confirmed to have film loss in the exposed area and resist residue in the unexposed area after dry development after hard baking. Even if the base polymer contains an acid unstable group with carbon number 10 that does not volatilize after hard baking, step and pattern separation after dry development can be achieved in resist evaluation samples with carbon numbers 4-9. However, compared with the resist composition of the base polymer protected by a single acid unstable group, the residue after dry development is thinner. Furthermore, the greater the protection rate of acid unstable groups that volatilize during hard baking, the greater the film loss in the exposed area, and the thicker the residue in the unexposed area after dry development.

[0181] (Evaluation of resist pattern formation 3) Table 6 shows examples of resisting compositions using water-repellent agents with added ArF wetting agents, and examples of using coating-type surface coating films instead of water-repellent agents (Resistant Pattern Formation Evaluation 3).

[0182] [Table 6] Sample Name inhibitor composition Acid unstable groups 100% protection rate Photoacid generator AG 1 copy Quenching agent Q1 Water-repellent PF 1 solvent PGMEA% Inhibitor Pattern Formation Rating 3 R31 AL4 10 5 5 100 R32 AL4 10 5 0 100

[0183] Multilayer films were formed on the substrate (SiO film) of the wafer (coated carbon film was processed at 250°C for 60 seconds to form a 54nm coating, and Si-containing antireflective film was processed at 220°C for 60 seconds to form an 18nm coating). The resist compositions listed in Table 6 were then coated onto each of these layers by spin coating and pre-baking. The pre-baking was performed at 120°C for 60 seconds to obtain sample wafers with a resist film thickness of 130nm.

[0184] Next, a surface coating agent composed of alcohol solvent was spin-coated onto the evaluation resist sample wafer without water-repellent agent, and baked at 100°C for 60 seconds to form a surface coating film with a thickness of 30 nm.

[0185] Next, using an ArF immersion exposure machine with a lens numerical aperture of 1.35 NA, the line and spacing pattern formed on the binary photomask with a half-pitch of 40 nm was exposed under a fixed exposure condition of 25 mJ / cm². Following this, each exposed wafer was subjected to a PEB (Post Exposure Bake) treatment at 90°C for 90 seconds on a heated plate, followed by a hard bake at 150°C for 30 seconds.

[0186] The step difference between the exposed and unexposed areas of each sample after hard baking was measured using an AFM (Atomic Force Microscope). Then, the resist residue in the unexposed areas was measured after dry development under oxygen-containing gas plasma conditions. The results are shown in Table 7. The dry development conditions are described below. Chamber pressure: 30mT RF power output (upper section): 200W RF power at the bottom: 100W O2 gas flow rate: 20 sccm N2 gas flow rate: 290 sccm Etching time: 6 seconds

[0187] [Table 7] Film loss in the exposed section after hard baking (nm) The residual resist film thickness after dry development is nm R31 70.0 95.0 R32 70.0 95.0

[0188] Even when the surface coating film is formed on a film composed of resist components, it is still confirmed that the film loss of the exposed area after hard baking and the pattern separation caused by dry development are still present.

[0189] (Evaluation of resist pattern formation 4) Table 8 shows examples used to investigate the pattern edge roughness of dry development and the pattern edge roughness of general alkaline wet development (comparative example).

[0190] [Table 8] sample wafer inhibitor composition Sample Name Acid unstable group Protection rate % Photoacid generator 10 copies Quenching agent 5 copies solvent PGMEA% SL1 R41 AL4 100 AG1 Q1 100 SL2 R42 AL4 90 AG1 Q1 100 SL3 R43 AL4 80 AG1 Q1 100 SL4 R44 AL4 70 AG1 Q1 100 SL5 R45 AL4 60 AG1 Q1 100 SL6 R46 AL4 50 AG1 Q1 100 SL7 R47 AL4 40 AG1 Q1 100 SL8 R48 AL4 10 AG1 Q1 100 RF1 Self-made positive chemical amplification inhibitor composition with non-wetting surface coating

[0191] Multilayer films were formed on the processed film (SiO film) of the wafer (coated carbon film was processed at 250°C for 60 seconds to form a 54nm coating, and Si-containing antireflective film was processed at 220°C for 60 seconds to form an 18nm coating). On top of these layers, resist compositions (SL1~SL8) from Table 8 and the resist composition (RF1) of the comparative example were formed by spin coating and pre-baking. Pre-baking was performed at 120°C for 60 seconds to obtain sample wafers with a resist film thickness of 130nm.

[0192] Next, for SL1 to SL8 in the embodiments, an ArF immersion exposure machine was used to expose the line and spacing patterns formed on the binary photomask with a half-pitch of 40 nm at a lens numerical aperture of 1.35 NA under a fixed exposure condition of 25 mJ / cm2. Then, each exposed wafer was subjected to PEB (Post Exposure Bake) treatment at 90°C for 90 seconds on a heated plate, followed by hard baking at 150°C for 30 seconds on a heated plate.

[0193] Next, for SL1 to SL8 in the embodiments, the exposed sections are etched back under oxygen-containing gas plasma conditions to separate the resist patterns. The dry development conditions at this time are as follows. Chamber pressure: 30mT RF power output (upper section): 200W RF power at the bottom: 100W O2 gas flow rate: 20 sccm N2 gas flow rate: 290 sccm Etching time: 6 seconds

[0194] On the other hand, regarding the development of the comparative example, a wafer with an resist pattern was produced by developing with 2.38% TMAH for 15 seconds, followed by DIW washing for 25 seconds, and then rotary drying.

[0195] Next, the wafers of the embodiments and the comparative examples were each etched and transferred to a Si-containing antireflective film on a multilayer substrate under the following dry etching conditions. Chamber pressure: 50mT RF power output (upper section): 500W RF power lower part: 300W CF4 gas flow rate: 150 sccm CHF3 gas flow rate: 50 sccm Etching time: 10 seconds

[0196] The opening length of the Si-containing antireflective coating was determined using low-accelerating voltage length-sensing SEM. The results are shown in Figure 9.

[0197] Next, the pattern of the aforementioned Si-containing anti-reflective film transfer is used as a mask for etching and transferring onto the underlying coated carbon film. The etching conditions at this time are as follows. Chamber pressure: 30mT RF power output (upper section): 200W RF power at the bottom: 100W O2 gas flow rate: 30 sccm N2 gas flow rate: 270 sccm Etching time: 15 seconds

[0198] The spacing dimension of the coated carbon film was determined using a low-accelerating voltage length-measuring SEM. The opening length of the coated carbon film was also determined using a low-accelerating voltage length-measuring SEM. The results are shown in Table 9.

[0199] [Table 9] Sample Name Before exposure Residual film nm PEB after Exposed part residual film nm Hard baking Unexposed residual film nm Hard baking Exposed part residual film nm After dry development Unexposed residual film nm Si-containing anti-reflective Membrane opening CD nm Coated carbon Membrane opening CD nm Coated carbon membrane LWR nm R41 130 130 120 50 95 40 53 2.0 R42 130 130 120 53 93 40 42 2.1 R43 130 130 120 57 90 40 41 2.2 R44 130 130 120 61 75 40 40 2.9 R45 130 130 120 65 64 50 50 4.1 R46 130 130 120 71 52 67 67 5.6 R47 130 130 120 77 45 77 77 7.5 R48 130 130 120 105 35 80 80 7.5 RF1 130 130 Not applicable Not applicable Not applicable 40 40 2.6

[0200] In the examples (R41-R48) with a protection rate of 10% to 100%, etching and transfer of coated carbon films to the lower layers of the multilayer were confirmed. Furthermore, the examples (R41-R43) with a resist composition having 80% to 100% substitution (protection) of an acid unstable group with 9 carbon atoms showed better LWR (Line Width Roughness) compared to the comparative example (RF1).

[0201] In the examples (R44~R48) of resist compositions with a protection rate of less than 80%, the resist size increased and the roughness increased. However, if the mask offset and etching conditions of the photomask were optimized in each example, the results were improved.

[0202] This specification contains the following specifications. [1]: A pattern forming method, characterized by comprising the following steps: Forming multiple layers on the substrate being processed An ArF excimer positive chemical amplification system inhibitor composition is used to form an inhibitor top film by comprising at least a base polymer having a (meth)acrylic acid structure substituted with an acid-instable group, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent. The acid-indestructible groups in the exposed portion of the aforementioned resist upper film are removed through exposure and post-exposure baking. A harder baking process, with a higher temperature and shorter duration than the aforementioned post-exposure baking, is performed to cause the aforementioned detached unstable acid groups to volatilize to the outer layer of the aforementioned resist film, creating a difference in the number of carbons between the unexposed and exposed areas. Using an oxygen-containing gaseous plasma, the resist layer film of the aforementioned exposure section is removed by dry development to separate the pattern and... The pattern of the aforementioned upper layer of the resist film is etched and transferred to the aforementioned multilayer layer below. [2]: The pattern forming method described in [1] above, wherein the base polymer uses a (meth)acrylic acid structure having a substitution rate of 80% to 100% for the aforementioned acid unstable group, and the aforementioned acid unstable group has 4 to 9 carbon atoms. [3]: The pattern forming method as described in [1] or [2] above, wherein the aforementioned base polymer is one that does not have an lactone structure. [4]: The pattern forming method of any one of [1] to [3] above, wherein the aforementioned exposure baking is performed at 80°C to 120°C for 40 to 120 seconds, and the aforementioned hard baking is performed at 130°C or above for less than 40 seconds. [5]: The pattern forming method of any of [1] to [4] above, wherein the aforementioned resist composition uses a surfactant that further contains a surface coating function that has ArF wetting exposure, or includes a step of forming a surface coating before the aforementioned exposure.

[0203] Furthermore, this invention is not limited to the embodiments described above. The embodiments described above are examples, and those that have substantially the same structure and perform the same function as the technical concept described in the claims of this invention are all included within the technical scope of this invention.

[0204] 1,21: Wafer substrate 2,22: The film being processed 3,23: Coated carbon film 3a, 23a: Coated carbon film patterns 4,24: Coated Si-containing antireflective film 4a, 24a: Patterns of Si-containing antireflective coatings 5,25:ArF positive chemical amplification inhibitor upper film 5a, 25a: Acid-instable groups have been deprotected by the resist in exposed areas. 5b, 25b: Resist pattern (unexposed area) 6.26: Reticle 7,27: The Light of ArF Exposure 28, 28a: Wetting surface coating film

Claims

1. A pattern forming method, characterized by comprising the following steps: forming a multilayer on a substrate; forming a resist upper layer film using an ArF excimer positive chemical amplification system resist composition comprising at least a base polymer having a (meth)acrylic acid structure substituted with acid-instable groups, a photoacid generator, a quencher for controlling acid diffusion, and an organic solvent; removing the acid-instable groups from the exposed portions of the resist upper layer film by exposure and post-exposure baking; performing a hard bake at a higher temperature and for a shorter time than the post-exposure baking, causing the removed acid-instable groups to volatilize outside the resist upper layer film, generating a difference in carbon number between the unexposed and exposed portions; separating the pattern by dry development of the resist upper layer film in the exposed portions using an oxygen-containing gas plasma; and etching and transferring the pattern of the resist upper layer film to the lower layer of the multilayer.

2. As in the pattern forming method of request item 1, wherein, The base polymer uses a (meth)acrylic acid structure with a substitution rate of 80% to 100% for the acid-instable group, and the acid-instable group has 4 to 9 carbon atoms.

3. The pattern forming method as described in claim 1 or 2, wherein, The base polymer uses those that do not have an lactone structure.

4. The pattern forming method as described in claim 1 or 2, wherein, The exposure and baking are performed at 80°C to 120°C for 40 to 120 seconds, and the hard baking is performed at 130°C or above for less than 40 seconds.

5. The pattern forming method as described in claim 1 or 2, wherein, The inhibitor composition uses a surfactant that contains a surface coating function with ArF wetting exposure, or includes a step of forming a surface coating before the exposure.

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