Positive resist material and pattern forming method

Abstract

To provide a positive resist material having sensitivity surpassing that of the conventional positive resist materials, and having small variations in dimension, and a patterning method.SOLUTION: A positive resist material comprises: a base polymer comprising a repeat unit in which hydrogen atoms of two carboxy groups are respectively substituted with two tertiary carbons binding to a double bond or a triple bond; and an acid generator.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a positive resist material and a patterning method.

Background Art

[0002] With the high integration and high speed of LSIs, the miniaturization of pattern rules has been rapidly progressing. In particular, the expansion of the logic memory market due to the spread of smartphones has been driving miniaturization, and high-performance semiconductors are required for the use of artificial intelligence (AI) and high-speed communication 5G, accelerating the progress of miniaturization. As the most advanced miniaturization technology, mass production of 7nm node devices by double patterning of ArF immersion lithography and 5nm node devices by extreme ultraviolet (EUV) lithography is in progress. EUV lithography is also listed as a candidate for the next-generation 3nm node and the successive-generation 2nm node.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. In order to ensure the resolution of fine patterns with a dimensional size of 45 nm or less, it has been proposed that not only the improvement of the dissolution contrast conventionally proposed but also the control of acid diffusion is important (Non-Patent Document 1). However, since chemically amplified resist materials increase the sensitivity and contrast by acid diffusion, if the post-exposure bake (PEB) temperature is lowered or the time is shortened to suppress acid diffusion to the limit, the sensitivity and contrast will be significantly reduced.

[0004] The triangular trade-off relationship among sensitivity, resolution, and edge roughness is shown. In order to improve the resolution, it is necessary to suppress acid diffusion, but when the acid diffusion distance becomes short, the sensitivity decreases.

[0005] It is effective to suppress acid diffusion by adding an acid generator that generates a bulky acid. Therefore, it has been proposed to include a repeating unit derived from an onium salt having a polymerizable unsaturated bond in a polymer. At this time, the polymer also functions as an acid generator (polymer-bound type acid generator). Patent Document 1 proposes a sulfonium salt or iodonium salt having a polymerizable unsaturated bond that generates a specific sulfonic acid. Patent Document 2 proposes a sulfonium salt in which a sulfonic acid is directly bonded to the main chain.

[0006] Chemically amplified resists have contributed not only to the merit of high sensitivity but also to the improvement of the contrast of the resist. In particular, a resist with high contrast is required for the formation of particularly fine two-dimensional patterns. In a positive resist, the contrast is improved by increasing the alkali dissolution rate due to the deprotection reaction during the heating (PEB) of the acid catalyst generated by light exposure. As an acid-labile group for the deprotection reaction, a resist composition using a crosslinked acetal in which one acid-labile group replaces between polymers of polyhydroxystyrene has been proposed (Patent Document 3). This is a high-contrast resist in which the alkali dissolution rate increases not only by the change in polarity due to the normal deprotection reaction but also by the decrease in molecular weight.

[0007] When a carboxyl group having a higher acidity than a phenol group is replaced with an acid-labile group, the alkali dissolution rate after deprotection increases. Therefore, a copolymer of polymethacrylic acid substituted with an acid-labile group has come to be used rather than the acid-labile group substitution of polyhydroxystyrene (Patent Document 4). For further improvement of the dissolution contrast, a resist material based on a polymer crosslinked with a tertiary ester, which is an acid-labile group between polymers, has been proposed (Patent Documents 5 and 6). Furthermore, a resist based on a hybrid polymer of acetal crosslinking and tertiary ester crosslinking has also been proposed (Patent Document 7).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

[0009] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] In view of the above circumstances, the present invention aims to provide a positive resist material having higher sensitivity than conventional positive resist materials and having small dimensional variations, and a patterning method. [Means for Solving the Problems]

[0011] In order to solve the above problems, the present invention provides a positive resist material including a base polymer containing a repeating unit in which hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond, and an acid generator, wherein the repeating unit in which hydrogen atoms of the two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond is represented by repeating unit a in the following formula (1). [Chemical Formula] [In the formula, R A is the same or different and is a hydrogen atom or a methyl group. X 1 , X 3 is a single bond, a phenylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond, an ether bond, and a lactone ring, provided that it is not the following formula (1’). R 1 ~R 4 is a linear, branched, or cyclic alkyl group having 1 to 8 carbon atoms, and R 1 and R 2 , R 3 and R 4 may combine to form a ring. X 2 is a vinylene group or an ethynylene group.]

Chemical formula

[0012] Such a positive resist material has a sensitivity superior to that of conventional positive resist materials and becomes a positive resist material with small dimensional variations.

[0013] Further, in the present invention, it is preferable that the acid generator is a sulfonium salt or an iodonium salt of a sulfonic acid containing an aromatic ring substituted with an iodine atom.

[0014] Such a positive resist material can control acid diffusion.

[0015] At this time, it is preferable that the sulfonium salt or iodonium salt of the sulfonic acid containing an aromatic ring substituted with the iodine atom is represented by the following formula (2-1) or (2-2).

Chemical formula

[0016] In the case of a positive resist material containing such an acid generator, acid diffusion can be more effectively controlled.

[0017] Further, in the present invention, it is preferable that the base polymer further contains at least one selected from a repeating unit in which the hydrogen atom of the carboxy group is substituted with a first acid-labile group other than two tertiary carbons each bonding to the double bond or triple bond, and a repeating unit in which the hydrogen atom of the phenolic hydroxy group is substituted with a second acid-labile group.

[0018] In the case of such a positive resist material, the effects of the present invention can be further improved.

[0019] At this time, it is preferable that the repeating unit substituted with the first acid-labile group is a repeating unit represented by the following formula (b1), and the repeating unit substituted with the second acid-labile group is a repeating unit represented by the following formula (b2).

Chemical formula

[0020] For a positive resist material containing such a repeating unit, the effects of the present invention can be further improved.

[0021] Further, in the present invention, it is preferable that the base polymer further contains a repeating unit containing an adhesion group selected from a hydroxy group, a carboxy group, a lactone ring, a carbonate group, a thiocarbonate group, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O-C(=O)-S-, and -O-C(=O)-NH-.

[0022] With such a positive resist material, the adhesion can be improved.

[0023] Moreover, in the present invention, it is preferably further included one or more selected from an organic solvent, a quencher, and a surfactant.

[0024] Such components can be added to the positive resist material of the present invention.

[0025] In addition, the present invention provides a patterning method including a step of forming a resist film on a substrate using the positive resist material described above, a step of exposing the resist film to high-energy rays, and a step of developing the exposed resist film using a developer.

[0026] With such a patterning method, it has higher sensitivity than conventional positive resist materials and is suitable for patterning of positive resist materials with small dimensional variations.

[0027] At this time, it is preferable that the high-energy rays are i-line, KrF excimer laser light, ArF excimer laser light, electron beam or extreme ultraviolet rays with a wavelength of 3 to 15 nm.

[0028] With such a patterning method, it is suitable for fine patterning.

Effects of the Invention

[0029] The positive resist material of the present invention can enhance the decomposition efficiency of the acid generator, so it has a high effect of suppressing acid diffusion, is highly sensitive, has high resolution, and has good pattern shape, edge roughness, and dimensional variation after exposure. Therefore, due to these excellent characteristics, its practicality is extremely high, and it is very useful as a fine pattern forming material for photomasks for ultra-LSI manufacturing or EB lithography, or a pattern forming material for EB or EUV exposure. The positive resist material of the present invention can be applied to, for example, not only lithography in semiconductor circuit formation, but also the formation of mask circuit patterns, micromachines, and thin film magnetic head circuit formation.

Embodiments for Carrying Out the Invention

[0030] As described above, there has been a demand for the development of a positive resist material having a sensitivity higher than that of conventional positive resist materials and having small dimensional variations, and a pattern forming method.

[0031] The tertiary carbon bonded to the double bond or triple bond of the repeating unit contained in the base polymer of the positive resist material of the present invention has appropriate carbocation stability due to the electron-withdrawing effect of two ester groups. However, when one of the tertiary ester bonds is broken, the electron-withdrawing group disappears, so the progress rate of the deprotection reaction of the other tertiary ester group is very fast. That is, when one of them is deprotected, the deprotection reaction of the other proceeds rapidly at the same time, and it seems as if two acid-labile groups are deprotected simultaneously. Since these acid-labile groups are intermolecularly bonded, the dissolution contrast is also improved by the decrease in molecular weight due to the deprotection reaction.

[0032] On the one hand, the rate of acid diffusion is dominated by the progress of the initial deprotection reaction. Ester compounds of 2-phenyl-2-propanol with low activation energy and tertiary ester compounds having double bonds or triple bonds have very low activation energy, so the rates of both the deprotection reaction and acid diffusion are fast, and it is difficult to control these. The acid-labile group of the present invention enables control of acid diffusion because the rate of the initial deprotection reaction of either one of the ester groups and the acid diffusion rate are not so fast. Therefore, it is possible to obtain the maximum contrast with the minimum acid diffusion.

[0033] As a result of intensive studies to obtain a positive resist material with high resolution, small edge roughness, and small dimensional variations, which has been demanded in recent years, the present inventors have found that it is necessary to shorten the acid diffusion distance to the limit. At this time, there is a problem that the resolution of two-dimensional patterns such as hole patterns deteriorates due to a decrease in sensitivity and a decrease in dissolution contrast. However, by using a polymer containing a repeating unit in which the hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond as a base polymer, it is possible to increase the dissolution contrast while simultaneously suppressing the acid diffusion distance to the limit. In particular, it has been found that it is extremely effective when used as a base polymer for a chemically amplified positive resist material.

[0034] That is, the present invention is a positive resist material comprising a base polymer containing a repeating unit in which the hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond, and an acid generator, wherein the repeating unit in which the hydrogen atoms of the two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond is represented by repeating unit a in the following formula (1). [Chemical formula] [In the formula, R A are the same or different and are a hydrogen atom or a methyl group. X 1 , X 3is a linking group having 1 to 12 carbon atoms containing at least one selected from a single bond, a phenylene group, or an ester bond, an ether bond, and a lactone ring, provided that it is not the following formula (1’). R 1 ~R 4 is a linear, branched, or cyclic alkyl group having 1 to 8 carbon atoms, R 1 and R 2 , R 3 and R 4 may combine to form a ring. X 2 is a vinylene group or an ethynylene group. ] [Chemical formula] (In the formula, the oxygen atom is bonded to the carbon atom of the carboxy group in the above formula (1). The dashed line represents a bond.)

[0035] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0036] [Positive resist material] The positive resist material of the present invention includes a base polymer containing a repeating unit (hereinafter also referred to as repeating unit a) in which the hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond, and an acid generator. Since the repeating unit in which the hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond has a high dissolution contrast, a resist film having a high dissolution contrast can be obtained by using a base polymer containing repeating unit a. The tertiary hydrocarbyl group means a group obtained by eliminating a hydrogen atom from a tertiary carbon atom of a hydrocarbon.

[0037] [Base polymer] The base polymer contained in the positive resist material of the present invention may contain another repeating unit in addition to the repeating unit a. Each of the following repeating units will be described in detail.

[0038] [Repeating unit a] Repeating unit a is represented by the following formula (a). [Chemical formula] [wherein, R A s are the same or different and are a hydrogen atom or a methyl group. X 1 , X 3 is a linking group having 1 to 12 carbon atoms containing at least one selected from a single bond, a phenylene group, or an ester bond, an ether bond, and a lactone ring, provided that it is not the following formula (1’). R 1 ~R 4 are linear, branched, or cyclic alkyl groups having 1 to 8 carbon atoms, and R 1 and R 2 , R 3 and R 4 may combine to form a ring. X 2 is a vinylene group or an ethynylene group.] [Chemical formula] (wherein, the oxygen atom is bonded to the carbon atom of the carboxy group in the above formula (1). The broken line represents a bond.)

[0039] In formula (a), R A is a hydrogen atom or a methyl group. X 1 , X 3 are a linking group having 1 to 12 carbon atoms containing at least one selected from a single bond, a phenylene group, or an ester bond, an ether bond, and a lactone ring, provided that it is not the above formula (1’). R 1 ~R 4 are linear, branched, or cyclic alkyl groups having 1 to 8 carbon atoms, and R 1 and R 2 , R 3 and R 4 may combine to form a ring. X 2 is a vinylene group or an ethynylene group.

[0040] R 1 ~R 4Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, n-hexyl group, and the like.

[0041] Examples of the monomer for obtaining the repeating unit a include, but are not limited to, those shown below. [Chemical formula]

[0042] [Chemical formula]

[0043] R A is as described above

[0044] [Repeating units b1, b2] The present invention essentially requires the repeating unit a having an acid-labile group represented by the above formula (a). However, the base polymer may further include at least one selected from the repeating unit b1 in which the hydrogen atom of the carboxy group is substituted with a first acid-labile group other than the two tertiary carbons bonded to the double bond or triple bond, and the repeating unit b2 in which the hydrogen atom of the phenolic hydroxy group is substituted with a second acid-labile group. It is preferable that the repeating unit b1 substituted with the first acid-labile group is a repeating unit represented by the following formula (b1), and the repeating unit b2 substituted with the second acid-labile group is a repeating unit represented by the following formula (b2). [Chemical formula] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group or a naphthylene group, or a linking group having 1 to 14 carbon atoms containing at least one selected from an ester bond, an ether bond and a lactone ring. Y 2 is a single bond, an ester bond or an amide bond. Y3 is a single bond, an ether bond or an ester bond. R 11 is each a first acid labile group other than two tertiary carbons bonded to a double bond or a triple bond. R 12 is a second acid labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a part of the carbon atoms thereof may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. However, 1 ≦ a + b ≦ 5.)

[0045] In formulas (b1) and (b2), R A is each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group or a naphthylene group, or a linking group having 1 to 14 carbon atoms containing at least one selected from an ester bond, an ether bond and a lactone ring. Y 2 is a single bond, an ester bond or an amide bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 is each a first acid labile group other than two tertiary carbons bonded to a double bond or a triple bond. R 12 is a second acid labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a part of the carbon atoms thereof may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. However, 1 ≦ a + b ≦ 5.)

[0046] Examples of the monomer that gives the repeating unit b1 include, but are not limited to, those shown below. In the following formulas, R A and R 11 are the same as described above.)

Chemical formula

[0047]

Chem.

[0048] Examples of the monomer that gives the repeating unit b2 include, but are not limited to, those shown below. In the following formula, R A and R 12 are the same as described above.

Chem.

[0049] R 11 or R 12 The acid-labile groups represented by are variously selected. For example, those represented by the following formulas (AL-1) to (AL-3) can be mentioned.

Chem.

[0050] In formula (AL-1), c is an integer of 0 to 6. R L1 is a tertiary hydrocarbyl group having 4 to 61 carbon atoms, preferably 4 to 15 carbon atoms, a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms, a carbonyl group, an ether bond, or a saturated hydrocarbyl group having 4 to 20 carbon atoms containing an ester bond, or a group represented by formula (AL-3).

[0051] R L1The tertiary hydrocarbyl group represented by is either saturated or unsaturated, and may be branched or cyclic. Specific examples thereof include a tert-butyl group, a tert-pentyl group, a 1,1-diethylpropyl group, a 1-ethylcyclopentyl group, a 1-butylcyclopentyl group, a 1-ethylcyclohexyl group, a 1-butylcyclohexyl group, a 1-ethyl-2-cyclopentenyl group, a 1-ethyl-2-cyclohexenyl group, a 2-methyl-2-adamantyl group, and the like. Examples of the trihydrocarbylsilyl group include a trimethylsilyl group, a triethylsilyl group, a dimethyl-tert-butylsilyl group, and the like. The saturated hydrocarbyl group containing a carbonyl group, an ether bond, or an ester bond may be linear, branched, or cyclic, but a cyclic one is preferred. Specific examples thereof include a 3-oxocyclohexyl group, a 4-methyl-2-oxooxan-4-yl group, a 5-methyl-2-oxooxolane-5-yl group, a 2-tetrahydropyranyl group, a 2-tetrahydrofuranyl group, and the like.

[0052] Examples of the acid-labile group represented by formula (AL-1) include a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tert-pentyloxycarbonyl group, a tert-pentyloxycarbonylmethyl group, a 1,1-diethylpropyloxycarbonyl group, a 1,1-diethylpropyloxycarbonylmethyl group, a 1-ethylcyclopentyloxycarbonyl group, a 1-ethylcyclopentyloxycarbonylmethyl group, a 1-ethyl-2-cyclopentenyl-oxycarbonyl group, a 1-ethyl-2-cyclopentenyl-oxycarbonylmethyl group, a 1-ethoxyethoxycarbonylmethyl group, a 2-tetrahydropyranyloxycarbonylmethyl group, a 2-tetrahydrofuranyloxycarbonylmethyl group, and the like.

[0053] Furthermore, examples of the acid-labile group represented by formula (AL-1) also include groups represented by the following formulas (AL-1)-1 to (AL-1)-10.

Chemical formula

[0054] In Formulas (AL-1)-1 to (AL-1)-10, c is the same as described above. R L8 is each independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. R L9 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R L10 is a saturated hydrocarbyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0055] In Formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18, preferably 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, an n-octyl group, and the like.

[0056] In Formula (AL-2), R L2 is a hydrocarbyl group having 1 to 18, preferably 1 to 10 carbon atoms, which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. Examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 18 carbon atoms, and some of the hydrogen atoms thereof may be substituted with a hydroxy group, an alkoxy group, an oxo group, an amino group, an alkylamino group, or the like. Examples of such substituted saturated hydrocarbyl groups include those shown below.

Chemical formula

[0057] R L2 and R L3 and, R L2 and RL4 or R L3 and R L4 and may form a ring together with the carbon atom to which they are attached, or with a carbon atom and an oxygen atom. In this case, R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. The number of carbon atoms in the ring formed by their combination is preferably 3 to 10, more preferably 4 to 10.

[0058] Among the acid-labile groups represented by formula (AL-2), linear or branched ones include, but are not limited to, those represented by the following formulas (AL-2)-1 to (AL-2)-69. In the following formulas, the dashed line represents a bond.

Chemical formula

[0059]

Chemical formula

[0060]

Chemical formula

[0061]

Chemical formula

[0062] Among the acid-labile groups represented by formula (AL-2), cyclic ones include a tetrahydrofuran-2-yl group, a 2-methyltetrahydrofuran-2-yl group, a tetrahydropyran-2-yl group, a 2-methyltetrahydropyran-2-yl group, and the like.

[0063] Examples of the acid-labile group include a group represented by the following formula (AL-2a) or (AL-2b). The base polymer may be crosslinked intermolecularly or intramolecularly by the acid-labile group. [Chemical formula] (In the formula, the dashed line represents a bond.)

[0064] In formula (AL-2a) or (AL-2b), R L11 and R L12 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 8 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Further, R L11 and R L12 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. In this case, R L11 and R L12 are each independently an alkanediyl group having 1 to 8 carbon atoms. R L13 are each independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. d and e are each independently an integer of 0 to 10, preferably an integer of 0 to 5, and f is an integer of 1 to 7, preferably an integer of 1 to 3.

[0065] In formula (AL-2a) or (AL-2b), L A is a (f + 1)-valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, a (f + 1)-valent alicyclic saturated hydrocarbon group having 3 to 50 carbon atoms, a (f + 1)-valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or a (f + 1)-valent heterocyclic group having 3 to 50 carbon atoms. Further, a part of the carbon atoms of these groups may be substituted with a heteroatom-containing group, and a part of the hydrogen atoms bonded to the carbon atoms of these groups may be substituted with a hydroxy group, a carboxy group, an acyl group, or a fluorine atom. As L A , a saturated hydrocarbon group such as a saturated hydrocarbylene group having 1 to 20 carbon atoms, a trivalent saturated hydrocarbon group, a tetravalent saturated hydrocarbon group, or an arylene group having 6 to 30 carbon atoms is preferable. The saturated hydrocarbon group may be linear, branched, or cyclic. LB is -C(=O)-O-, -NH-C(=O)-O-, or -NH-C(=O)-NH-.

[0066] Examples of the crosslinked acetal group represented by formula (AL-2a) or (AL-2b) include groups represented by the following formulas (AL-2)-70 to (AL-2)-77. [Chemical formula] (In the formula, the dashed line represents a bond.)

[0067] In formula (AL-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, and a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cyclic unsaturated hydrocarbyl group having 3 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, and the like. Further, R L5 and R L6 , R L5 and R L7 , or R L6 and R L7 may combine with each other to form an alicyclic ring having 3 to 20 carbon atoms together with the carbon atoms to which they are attached.

[0068] Examples of the group represented by formula (AL-3) include a tert-butyl group, a 1,1-diethylpropyl group, a 1-ethylnorbornyl group, a 1-methylcyclopentyl group, a 1-isopropylcyclopentyl group, a 1-ethylcyclopentyl group, a 1-methylcyclohexyl group, a 2-(2-methyl)adamantyl group, a 2-(2-ethyl)adamantyl group, a tert-pentyl group, and the like.

[0069] Further, examples of the group represented by formula (AL-3) also include groups represented by the following formulas (AL-3)-1 to (AL-3)-19. [Chemical formula] (In the formula, the dashed line represents a bond.)

[0070] In formulas (AL-3)-1 to (AL-3)-19, R L14 is independently a saturated hydrocarbyl group having 1 to 8 carbon atoms, an unsaturated hydrocarbyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R L15 and R L17 are independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. R L16 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Further, as the aryl group, a phenyl group or the like is preferable. R F is a fluorine atom or a trifluoromethyl group. g is an integer from 1 to 5.

[0071] Furthermore, examples of the acid-labile group include a group represented by the following formula (AL-3)-20 or (AL-3)-21. The polymer may be crosslinked intramolecularly or intermolecularly by the acid-labile group. [Chemical formula] (In the formula, the dashed line represents a bond.)

[0072] In formulas (AL-3)-20 and (AL-3)-21, R L14 is the same as described above. R L18 is a (h + 1)-valent saturated hydrocarbylene group having 1 to 20 carbon atoms or a (h + 1)-valent arylene group having 6 to 20 carbon atoms, and may contain a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. The saturated hydrocarbylene group may be linear, branched, or cyclic. h is an integer from 1 to 3.

[0073] Examples of the monomer that provides a repeating unit containing an acid-labile group represented by formula (AL-3) include (meth)acrylic acid esters containing an exo-form structure represented by the following formula (AL-3)-22. [Chemical formula]

[0074] In formula (AL-3)-22, R A is the same as described above. R Lc1 is a saturated hydrocarbyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. R Lc2 ~R Lc11 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms which may contain a hetero atom. Examples of the hetero atom include an oxygen atom. Examples of the hydrocarbyl group include an alkyl group having 1 to 15 carbon atoms and an aryl group having 6 to 15 carbon atoms. R Lc2 and R Lc3 and, R Lc4 and R Lc6 and, R Lc4 and R Lc7 and, R Lc5 and R Lc7 and, R Lc5 and R Lc11 and, R Lc6 and R Lc10 and, R Lc8 and R Lc9 and, or R Lc9 and R Lc10 and may combine with each other to form a ring together with the carbon atom to which they are attached. In this case, the group involved in the bond is a hydrocarbylene group having 1 to 15 carbon atoms which may contain a hetero atom. Further, R Lc2 and R Lc11 and, R Lc8 and R Lc11 and, or R Lc4 and R Lc6 and may be bonded to each other without any intervening group to the adjacent carbons to form a double bond. Note that this formula also represents enantiomers.

[0075] Here, examples of the monomer that gives the repeating unit represented by formula (AL-3)-22 include those described in JP-A-2000-327633. Specifically, the following are examples, but not limited thereto. In the following formulas, R A is the same as described above. [Chemical formula]

[0076] Examples of the monomer that gives the repeating unit containing an acid-labile group represented by formula (AL-3) also include (meth)acrylic acid esters containing a furandiyl group, a tetrahydrofurandiyl group, or an oxanorbornyldiyl group, represented by the following formula (AL-3)-23. [Chemical formula]

[0077] In formula (AL-3)-23, R A is the same as described above. R Lc12 and R Lc13 are each independently a hydrocarbyl group having 1 to 10 carbon atoms. R Lc12 and R Lc13 may be bonded to each other to form an alicyclic ring together with the carbon atom to which they are bonded. R Lc14 is a furandiyl group, a tetrahydrofurandiyl group, or an oxanorbornyldiyl group. R Lc15 is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups having 1 to 10 carbon atoms.

[0078] Examples of the monomer that gives the repeating unit represented by formula (AL-3)-23 include the following, but are not limited thereto. In the following formulas, R A is the same as described above, Ac is an acetyl group, and Me is a methyl group. [Chemistry]

[0079] [Chemistry]

[0080] [Repeating unit c] The base polymer may further contain a repeating unit c containing an adhesion group selected from a hydroxy group, a carboxy group, a lactone ring, a carbonate group, a thiocarbonate group, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O-C(=O)-S-, and -O-C(=O)-NH-.

[0081] Examples of the monomer that gives the repeating unit c include, but are not limited to, those shown below. In the following formulas, R A is the same as described above. [Chemistry]

[0082] [Chemistry]

[0083] [Chemistry]

[0084] [Chemistry]

[0085] [Chemistry]

[0086] [Chemistry]

[0087]

Chem.

[0088]

Chem.

[0089]

Chem.

[0090]

Chem.

[0091] [Repeating unit d] The base polymer may contain a repeating unit d other than the repeating units described above. However, the repeating unit does not contain an acid generator. Examples of the repeating unit d include those derived from styrene, acenaphthylene, indene, coumarin, coumarone, and the like.

[0092] In the base polymer, the content ratios of the repeating units a, b1, b2, c, and d are preferably 0 < a < 1.0, 0 ≤ b1 ≤ 0.9, 0 ≤ b2 ≤ 0.9, 0 ≤ c ≤ 0.9, and 0 ≤ d ≤ 0.9, more preferably 0.005 ≤ a ≤ 0.8, 0 ≤ b1 ≤ 0.8, 0 ≤ b2 ≤ 0.8, 0.1 ≤ b1 + b2 ≤ 0.8, 0 ≤ c ≤ 0.8, and 0 ≤ d ≤ 0.4, and even more preferably 0.01 ≤ a ≤ 0.7, 0 ≤ b1 ≤ 0.7, 0 ≤ b2 ≤ 0.7, 0.2 ≤ b1 + b2 ≤ 0.7, 0 ≤ c ≤ 0.7, and 0 ≤ d ≤ 0.3. However, a + b1 + b2 + c + d = 1.0.

[0093] To synthesize the base polymer, for example, a monomer that provides the above-described repeating unit may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0094] Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, dioxane, and the like. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, and the like. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0095] When copolymerizing a monomer containing a hydroxy group, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid such as an ethoxyethoxy group during polymerization, and then deprotected with a weak acid and water after polymerization, or may be substituted with an acetyl group, a formyl group, a pivaloyl group, etc., and then subjected to alkali hydrolysis after polymerization.

[0096] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and the acetoxy group may be deprotected by the above alkali hydrolysis after polymerization to obtain hydroxystyrene or hydroxyvinylnaphthalene.

[0097] Examples of the base used during alkali hydrolysis include aqueous ammonia, triethylamine, and the like. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0098] The base polymer preferably has a polystyrene-reduced weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, as measured by gel permeation chromatography (GPC) using THF as a solvent. If Mw is 1,000 or more, the resist material will not be inferior in heat resistance. If Mw is 500,000 or less, the alkali solubility will not decrease, and the trailing phenomenon will not easily occur after pattern formation.

[0099] Furthermore, as the pattern rules are miniaturized, the influence of Mw and molecular weight distribution (Mw / Mn) tends to increase. Therefore, in order to obtain a resist material suitably used for fine pattern dimensions, the Mw / Mn of the base polymer is preferably narrowly dispersed in the range of 1.0 to 2.0, particularly 1.0 to 1.5. If the molecular weight distribution (Mw / Mn) of the base polymer is within this range, there is no low molecular weight or high molecular weight polymer, so there is no risk of foreign matter being seen on the pattern or the pattern shape deteriorating after exposure.

[0100] The base polymer may contain two or more polymers having different composition ratios, Mw, and Mw / Mn. Also, a polymer containing repeating unit a and a polymer not containing repeating unit a but containing repeating units b1 to b2 may be blended.

[0101] [Acid generator] The positive resist material of the present invention further contains an acid generator that generates a strong acid (hereinafter also referred to as an additive acid generator). The strong acid referred to here means a compound having sufficient acidity to cause a deprotection reaction of the acid-labile group of the base polymer. Examples of the acid generator include compounds that generate an acid upon exposure to actinic rays or radiation (photoacid generators). The photoacid generator is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy rays, but those that generate sulfonic acid, imidic acid, or methidic acid are preferred. Preferred photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. Specific examples of the photoacid generator include those described in paragraphs

[0122] to

[0142] of JP-A-2008-111103.

[0102] Also, as the photoacid generator, a sulfonium salt represented by the following formula (1-1) or an iodonium salt represented by the following formula (1-2) can also be preferably used.

Chemical formula

[0103] In formulas (1-1) and (1-2), R 101 ~R 105 are each independently a hydrocarbyl group having 1 to 25 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hetero atom.

[0104] R 101 ~R 105The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group, etc.; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, propenyl group, butenyl group, hexenyl group, etc.; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group, norbornenyl group, etc.; alkynyl groups having 2 to 20 carbon atoms such as ethynyl group, propynyl group, butynyl group, etc.; aryl groups having 6 to 20 carbon atoms such as phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, etc.; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, phenethyl group, etc. Further, a part of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, etc., and a part of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0105] Also, R 101 and R 102They may combine to form a ring together with the sulfur atom to which they are attached. At this time, the ring is preferably one having the structure shown below. [Chemical formula] (In the formula, the dashed line is a bond to R 103 .)

[0106] Examples of the cation of the sulfonium salt represented by formula (1-1) include, but are not limited to, those shown below.

[0107] [Chemical formula]

[0108] [Chemical formula]

[0109] [Chemical formula]

[0110] [Chemical formula]

[0111] [Chemical formula]

[0112] [Chemical formula]

[0113] [Chemical formula]

[0114] [Chemical formula]

[0115]

Chem.

[0116]

Chem.

[0117]

Chem.

[0118]

Chem.

[0119]

Chem.

[0120]

Chem.

[0121]

Chem.

[0122]

Chem.

[0123]

Chem.

[0124]

Chem.

[0125] [Chemical]

[0126] Examples of the cation of the iodonium salt represented by the formula (1-2) include, but are not limited to, those shown below. [Chemical]

[0127] In the formulas (1-1) and (1-2), X - is an anion selected from the following formulas (1A) to (1D). [Chemical]

[0128] In the formula (1A), R fa is a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the same ones as those described later for the hydrocarbyl group represented by R 107 in the following formula (1A’).

[0129] As the anion represented by the formula (1A), those represented by the following formula (1A’) are preferable. [Chemical]

[0130] In the formula (1A’), R 106 is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R 107 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. As the heteroatom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom and the like are preferable, and an oxygen atom is more preferable. As the hydrocarbyl group, those having 6 to 30 carbon atoms are particularly preferable from the viewpoint of obtaining high resolution in fine pattern formation.

[0131] R 107 The hydrocarbyl group represented by [R] may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group; cycloalkyl saturated hydrocarbyl groups such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group; unsaturated hydrocarbyl groups such as allyl group, 3-cyclohexenyl group; aryl groups such as phenyl group, 1-naphthyl group, 2-naphthyl group, anthracenyl group, indenyl group, fluorenyl group, pyrenyl group; aralkyl groups such as benzyl group, diphenylmethyl group, etc.

[0132] Also, some or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, etc., and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. Examples of the hydrocarbyl group containing a heteroatom include tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxymethyl group, 2-carboxy-1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, 3-oxocyclohexyl group, etc.

[0133] Regarding the synthesis of sulfonium salts containing anions represented by formula (1A’), details can be found in JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, etc. Further, sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644, etc. are also preferably used.

[0134] Examples of the anion represented by formula (1A) include the same ones as those exemplified as the anion represented by formula (1A) in JP-A-2018-197853.

[0135] In formula (1B), R fb1 and R fb2 are each independently a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the same ones as those exemplified in the description of R 107 in formula (1A’). Preferably, R fb1 and R fb2 are a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fb1 and R fb2 may be bonded to each other to form a ring together with the group (-CF 2 -SO 2 -N - -SO 2 -CF 2 -) to which they are bonded. At this time, the group obtained by bonding R fb1 and R fb2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0136] In formula (1C), R fc1 , R fc2 , and R fc3is independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A’). 107 include the same ones as those exemplified in the description of fc1 . R fc2 , and R fc3 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fc1 and R fc2 may be bonded to each other to form a ring together with the group (-CF 2 -SO 2 -C - -SO 2 -CF 2 -) to which they are bonded. At this time, the group obtained by bonding R fc1 and R fc2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0137] In formula (1D), R fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the same ones as those exemplified in the description of R 107 in formula (1A’).

[0138] Regarding the synthesis of the sulfonium salt containing the anion represented by formula (1D), it is detailed in JP-A-2010-215608 and JP-A-2014-133723.

[0139] Examples of the anion represented by formula (1D) include the same ones as those exemplified as the anion represented by formula (1D) in JP-A-2018-197853.

[0140] In addition, the photoacid generator containing the anion represented by formula (1D) has sufficient acidity to cleave the acid-labile group in the base polymer because it does not have fluorine at the α-position of the sulfo group but has two trifluoromethyl groups at the β-position. Therefore, it can be used as a photoacid generator.

[0141] Furthermore, as the photoacid generator, those represented by the following formula (2) can also be preferably used. [Chemical formula]

[0142] In formula (2), R 201 and R 202 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. R 203 is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. Also, R 201 and R 202 , or R 201 and R 203 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. At this time, as the ring, in the description of formula (1-1), those similar to the rings that can be formed together with the sulfur atom to which R 101 and R 102 are bonded are exemplified.

[0143] R 201 , and R 202The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclic saturated hydrocarbyl groups such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group; aryl groups such as phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, anthracenyl group, etc. Further, some or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, etc., and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, etc. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0144] R 203The hydrocarbylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkane diyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group; cyclic saturated hydrocarbylene groups such as cyclopentane diyl group, cyclohexane diyl group, norbornane diyl group, adamantane diyl group; arylene groups such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, tert-butylnaphthylene group. Further, some or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, halogen atom, and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atom, sulfur atom, nitrogen atom, and as a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate group, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferable.

[0145] In formula (2), L 1 is a single bond, an ether bond, or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R203 Examples thereof include those similar to those exemplified as the hydrocarbylene group represented by

[0146] In formula (2), X A , X B , X C , and X D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, at least one of X A , X B , X C and X D is a fluorine atom or a trifluoromethyl group.

[0147] In formula (2), k is an integer from 0 to 3.

[0148] As the photoacid generator represented by formula (2), those represented by the following formula (2') are preferred.

Chemical formula

[0149] In formula (2'), L 1 is the same as described above. R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R 301 , R 302 , and R 303 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to those exemplified in the description of R 107 in formula (1A'). x and y are each independently an integer from 0 to 5, and z is an integer from 0 to 4.

[0150] Examples of the photoacid generator represented by formula (2) include those similar to those exemplified as the photoacid generator represented by formula (2) in JP-A-2017-026980.

[0151] Among the photoacid generators, those containing an anion represented by formula (1A') or (1D) have low acid diffusion and excellent solubility in the resist solvent, and are particularly preferred. Also, those represented by formula (2') have extremely low acid diffusion and are particularly preferred.

[0152] Furthermore, the photoacid generator can also be a sulfonium salt or an iodonium salt of a sulfonic acid containing an aromatic ring substituted with an iodine atom. Examples of such salts include those in which the sulfonium salt or iodonium salt of a sulfonic acid containing an aromatic ring substituted with the iodine atom is represented by the following formula (2-1) or (2-2). The aromatic ring substituted with the iodine atom may be substituted with a bromine atom instead of the iodine atom.

Chemical formula

[0153] In formulas (2-1) and (2-2), p is an integer of 1 ≦ p ≦ 3, q and r are integers of 1 ≦ q ≦ 5, 0 ≦ r ≦ 3, and 1 ≦ q + r ≦ 5, and preferably, q is an integer of 1 ≦ q ≦ 3 and r is an integer of 0 ≦ r ≦ 2.

[0154] L 11 is a linear, branched, or cyclic saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain a single bond, an ether bond, or an ester bond. L 12 is a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and is a trivalent or tetravalent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, a nitrogen atom, a chlorine atom, a bromine atom, or an iodine atom.

[0155] R 401 is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, which may contain a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, or an ether bond, or -NR 401A-C(=O)-R 401B 、 or -NR 401A -C(=O)-O-R 401B is.

[0156] R 401A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. R 401B is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When p and / or r is 2 or more, each R 401 may be the same as or different from each other.

[0157] Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of these is a fluorine atom or a trifluoromethyl group, and Rf 11 and Rf 12 may combine to form a carbonyl group.

[0158] R 402 、R 403 、R 404 、R 405 、 and R 406is independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Further, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone group, a sulfone group, or a sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate group, or a sulfonic acid ester bond. Also, R 402 and R 403 may combine with each other to form a ring together with the sulfur atom to which they are attached. R 402 R 403 R 404 R 405 and R 406 Specific examples of 101 to R 105 include those similar to those represented by the above R

[0159] Examples of the anion of the onium salt represented by formula (2-1) or (2-2) include, but are not limited to, those shown below.

Chemical formula

[0160]

Chemical formula

[0161]

Chemical formula

[0162]

Chemical formula

[0163]

Chemical formula

[0164]

Chem.

[0165]

Chem.

[0166]

Chem.

[0167]

Chem.

[0168]

Chem.

[0169]

Chem.

[0170]

Chem.

[0171]

Chem.

[0172]

Chem.

[0173]

Chem.

[0174] [Chemistry]

[0175] [Chemistry]

[0176] [Chemistry]

[0177] [Chemistry]

[0178] [Chemistry]

[0179] [Chemistry]

[0180] [Chemistry]

[0181] [Chemistry]

[0182] [Chemistry]

[0183] [Chemistry]

[0184] [Chemistry]

[0185]

Chem.

[0186]

Chem.

[0187]

Chem.

[0188]

Chem.

[0189]

Chem.

[0190]

Chem.

[0191]

Chem.

[0192]

Chem.

[0193]

Chem.

[0194]

Chem.

[0195] [Chemical]

[0196] [Chemical]

[0197] [Chemical]

[0198] [Chemical]

[0199] [Chemical]

[0200] [Chemical]

[0201] [Chemical]

[0202] [Chemical]

[0203] [Chemical]

[0204] [Chemical]

[0205] [Chemical]

[0206]

Chem.

[0207]

Chem.

[0208]

Chem.

[0209]

Chem.

[0210]

Chem.

[0211] In the positive resist material of the present invention, the content of the additive acid generator is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, based on 100 parts by mass of the base polymer. By including the additive acid generator, the positive resist material of the present invention functions as a chemically amplified positive resist material. Further, by including the repeating unit d in the base polymer, the function of the positive resist material of the present invention as a chemically amplified positive resist material can be improved.

[0212] [Organic solvent] An organic solvent may be blended in the positive resist material of the present invention. The organic solvent is not particularly limited as long as it can dissolve each of the above-described components and each of the components described below. Examples of such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl 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, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0213] In the positive resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer.

[0214] [Quencher] A quencher may be blended in the positive resist material of the present invention. Examples of the quencher include conventional basic compounds. Examples of the conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, and the like. In particular, the primary, secondary, and tertiary aliphatic amines described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly aliphatic amines having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649 are preferable. By adding such a basic compound, for example, the acid diffusion rate in the resist film can be further suppressed or the shape can be corrected.

[0215] In addition, examples of the quencher include sulfonic acids in which the α-position is not fluorinated and onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids described in JP-A-2008-158339. Sulfonic acids, imidic acids, or methidic acids in which the α-position is fluorinated are necessary for deprotecting the acid-labile group of the carboxylic acid ester, but sulfonic acids or carboxylic acids in which the α-position is not fluorinated are released by salt exchange with onium salts in which the α-position is not fluorinated. Since sulfonic acids and carboxylic acids in which the α-position is not fluorinated do not cause a deprotection reaction, they function as a quencher.

[0216] Examples of such a quencher include a compound represented by the following formula (B) (onium salt of a sulfonic acid in which the α-position is not fluorinated), a compound represented by the following formula (C) (onium salt of a carboxylic acid), and an onium salt of an alkoxide represented by the following formula (D).

Chemical formula

[0217] In formula (B), R 501 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom, provided that the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is excluded from those substituted with a fluorine atom or a fluoroalkyl group.

[0218] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclic saturated hydrocarbyl groups such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, adamantylmethyl group; alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl group; aryl groups such as phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.); heteroaryl groups such as thienyl group; aralkyl groups such as benzyl group, 1-phenylethyl group, 2-phenylethyl group, etc.

[0219] Also, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc., and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, etc. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. Examples of the hydrocarbyl group containing a heteroatom include alkoxyphenyl groups such as 4-hydroxyphenyl group, 4-methoxyphenyl group, 3-methoxyphenyl group, 2-methoxyphenyl group, 4-ethoxyphenyl group, 4-tert-butoxyphenyl group, 3-tert-butoxyphenyl group, etc.; alkoxynaphthyl groups such as methoxynaphthyl group, ethoxynaphthyl group, n-propoxynaphthyl group, n-butoxynaphthyl group, etc.; dialkoxynaphthyl groups such as dimethoxynaphthyl group, diethoxynaphthyl group, etc.; aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl group, 2-(1-naphthyl)-2-oxoethyl group, 2-(2-naphthyl)-2-oxoethyl group, etc.

[0220] In formula (C), R 502 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. Examples of the hydrocarbyl group represented by R 502 include the same ones as those exemplified as the hydrocarbyl group represented by R 501 In addition, as other specific examples, fluorine-containing alkyl groups such as trifluoromethyl group, trifluoroethyl group, 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group, etc.; fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group, etc. may also be mentioned.

[0221] In formula (D), R 503 is a linear, branched, or cyclic alkyl group having 1 to 8 carbon atoms, or an aryl group, having at least 3 or more fluorine atoms, and may have a nitro group.

[0222] In formulas (B), (C), and (D), Mq + is an onium cation. As the onium cation, a sulfonium cation, an iodonium cation, or an ammonium cation is preferable, and a sulfonium cation or an iodonium cation is more preferable. As the sulfonium cation or the iodonium cation, those similar to the cations of the sulfonium salts represented by formula (1-1) and the cations of the iodonium salts represented by formula (1-2) exemplified respectively can be mentioned.

[0223] As the quencher, further, the polymer type quencher described in JP-A-2008-239918 can be mentioned. This enhances the rectangularity of the resist film after patterning by orienting on the surface of the resist film after coating. The polymer type quencher also has the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for liquid immersion exposure is applied.

[0224] In the positive resist material of the present invention, the content of the quencher is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass with respect to 100 parts by mass of the base polymer.

[0225] [Other Components] In addition to the components described above, by appropriately combining and blending a surfactant, a dissolution inhibitor, etc. according to the purpose to constitute a positive resist material, in the exposed part, the dissolution rate of the base polymer with respect to the developer is accelerated by a catalytic reaction, so that an extremely high-sensitivity positive resist material can be obtained. In this case, the dissolution contrast and resolution of the resist film are high, there is an exposure margin, the process adaptability is excellent, the pattern shape after exposure is good, and particularly acid diffusion can be suppressed, so the difference in rough and fine dimensional sizes is small, and from these facts, it has high practicality and can be made very effective as a resist material for ultra-LSI.

[0226] Examples of the surfactant include those described in paragraphs

[0165] to

[0166] of JP-A-2008-111103. By adding the surfactant, the coatability of the resist material can be further improved or controlled. In the positive resist material of the present invention, the content of the surfactant is preferably 0.0001 to 10 parts by mass with respect to 100 parts by mass of the base polymer. The surfactant can be used alone or in combination of two or more.

[0227] By blending a dissolution inhibitor, the difference in dissolution rate between the exposed portion and the unexposed portion can be further increased, and the resolution can be further improved. Examples of the dissolution inhibitor include a compound having a molecular weight preferably of 100 to 1,000, more preferably 150 to 800, and containing two or more phenolic hydroxy groups in the molecule, and in which the hydrogen atoms of the phenolic hydroxy groups are substituted as a whole by acid-labile groups at a ratio of 0 to 100 mol%, or a compound having a carboxy group in the molecule, and in which the hydrogen atoms of the carboxy group are substituted as a whole by acid-labile groups at an average ratio of 50 to 100 mol%. Specifically, compounds in which the hydrogen atoms of the hydroxy groups or carboxy groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalene carboxylic acid, adamantane carboxylic acid, cholic acid are substituted with acid-labile groups, etc. can be mentioned. For example, they are described in paragraphs

[0155] to

[0178] of JP-A-2008-122932.

[0228] The content of the dissolution inhibitor is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass with respect to 100 parts by mass of the base polymer. The dissolution inhibitor can be used alone or in combination of two or more.

[0229] In the positive resist material of the present invention, a water repellency improver for improving the water repellency of the resist surface after spin coating may be blended. The water repellency improver can be used in immersion lithography without using a top coat. As the water repellency improver, a polymer compound containing an alkyl fluoride group, a polymer compound containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue having a specific structure, etc. are preferable, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferable. The water repellency improver needs to be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the above-described specific 1,1,1,3,3,3-hexafluoro-2-propanol residue has good solubility in the developer. As the water repellency improver, a polymer compound containing a repeating unit containing an amino group or an amine salt has a high effect of preventing the evaporation of acid in PEB and preventing the opening defect of the hole pattern after development. In the positive resist material of the present invention, the content of the water repellency improver is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the base polymer. The water repellency improver can be used alone or in combination of two or more kinds.

[0230] Acetylenic alcohols may be blended in the positive resist material of the present invention. Examples of the acetylenic alcohols include those described in paragraphs

[0179] to

[0182] of JP-A-2008-122932. In the positive resist material of the present invention, the content of the acetylenic alcohols is preferably 0 to 5 parts by mass based on 100 parts by mass of the base polymer.

[0231] [Pattern formation method] When the positive resist material of the present invention is used for various integrated circuit manufacturing, known lithography techniques can be applied. For example, as a pattern formation method, a method including a step of forming a resist film on a substrate using the above-described resist material, a step of exposing the resist film with high energy rays, and a step of developing the exposed resist film using a developer can be mentioned.

[0232] First, the positive resist material of the present invention is applied onto a substrate for integrated circuit manufacturing (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflection film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc. so that the coating film thickness becomes 0.01 to 2 μm. This is prebaked on a hot plate, preferably at 60 to 150 °C for 10 seconds to 30 minutes, more preferably at 80 to 120 °C for 30 seconds to 20 minutes to form a resist film.

[0233] Next, the resist film is exposed using high-energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. When using ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. as the high-energy rays, the exposure dose is preferably about 1 to 200 mJ / cm 2 , more preferably about 10 to 100 mJ / cm 2 , and irradiation is performed using a mask for forming a target pattern directly or. When using EB as the high-energy ray, the exposure dose is preferably about 0.1 to 100 μC / cm 2 , more preferably about 0.5 to 50 μC / cm 2 , and writing is performed using a mask for forming a target pattern directly or. The positive resist material of the present invention is particularly suitable for fine patterning by i-line, KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet rays with a wavelength of 3 to 15 nm among high-energy rays, and is particularly suitable for fine patterning by EB or EUV.

[0234] After exposure, PEB may be performed on a hot plate or in an oven, preferably at 50 to 150 °C for 10 seconds to 30 minutes, more preferably at 60 to 120 °C for 30 seconds to 20 minutes.

[0235] After exposure or PEB, using a developer of an alkaline aqueous solution such as 0.1 to 10% by mass, preferably 2 to 5% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), etc., for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, developing by a conventional method such as dip method, puddle method, spray method, etc., the irradiated part is dissolved in the developer, and the unexposed part is not dissolved, and a desired positive pattern is formed on the substrate.

[0236] Negative development can also be performed to obtain a negative pattern by organic solvent development using the positive resist material. Examples of the developer used at this time include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents can be used alone or in combination of two or more.

[0237] At the end of development, rinsing can be performed. As the rinse liquid, a solvent that is miscible with the developer and does not dissolve the resist film is preferred. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, or alkynes having 6 to 12 carbon atoms, and aromatic solvents are preferably used.

[0238] Specifically, examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol, and the like.

[0239] Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, di-n-hexyl ether, and the like.

[0240] Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexyne, heptyne, octyne, etc.

[0241] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene, etc.

[0242] By performing rinsing, it is possible to reduce the collapse of the resist pattern and the occurrence of defects. Also, rinsing is not necessarily essential, and the amount of solvent used can be reduced by not performing rinsing.

[0243] The developed hole pattern or trench pattern can also be shrunk by thermal flow, RELACS technology, or DSA technology. A shrinking agent is applied onto the hole pattern, and cross-linking of the shrinking agent occurs on the surface of the resist due to the diffusion of the acid catalyst from the resist layer during baking, and the shrinking agent adheres to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the time is preferably 10 to 300 seconds to remove the excess shrinking agent and shrink the hole pattern.

Examples

[0244] Hereinafter, the present invention will be specifically described by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0245] [1] Synthesis of Monomers [Synthesis Example 1-1] Synthesis of Monomer 1 Dissolve 14.2 g of 2,5-dimethyl-3-hexyne-2,5-diol in 50 g of THF, and dropwise add 11.5 g of methacrylic acid chloride under ice cooling. After stirring at room temperature for 5 hours, add water to stop the reaction. After normal aqueous post-treatment, purification was performed by silica gel column chromatography to obtain monomer 1 represented by the following formula. [Chemical formula]

[0246] [Synthesis Example 1-2] Synthesis of Monomer 2 Change 2,5-dimethyl-3-hexyne-2,5-diol to 17.0 g of 3,6-dimethyl-4-octyne-3,6-diol, and obtain monomer 2 represented by the following formula by the same reaction. [Chemical formula]

[0247] [Synthesis Example 1-3] Synthesis of Monomer 3 Change 2,5-dimethyl-3-hexyne-2,5-diol to 14.4 g of 2,5-dimethyl-3-hexene-2,5-diol, and obtain monomer 3 represented by the following formula by the same reaction. [Chemical formula]

[0248] [Synthesis Example 1-4] Synthesis of Monomer 4 Change methacrylic acid chloride to 18.0 g of 4-styrenecarboxylic acid chloride, and obtain monomer 4 represented by the following formula by the same reaction. [Chemical formula]

[0249] [2] Synthesis of Polymer The ALG monomers 1 to 6, F monomer 1, and comparative monomer 1 used in the synthesis of the polymer are as follows. The Mw of the polymer is the polystyrene-equivalent measurement value by GPC using THF as the solvent. [Chemical formula]

[0250] [Synthesis Example 2-1] Synthesis of Polymer 1 To a 2 L flask, 1.7 g of monomer 1, 8.2 g of 1-methyl-1-cyclopentyl methacrylate, 5.9 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the reaction was carried out for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 1. The composition of Polymer 1 was 13 determined by C-NMR, and 1 Mw and Mw / Mn were confirmed by GPC using H-NMR. [Chemical formula]

[0251] [Synthesis Example 2-2] Synthesis of Polymer 2 To a 2 L flask, 1.9 g of monomer 1, 7.3 g of 1-methyl-1-cyclohexyl methacrylate, 6.4 g of 3-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the reaction was carried out for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 2. The composition of Polymer 2 was 13 determined by C-NMR, and 1 Mw and Mw / Mn were confirmed by GPC using H-NMR. [Chemical formula]

[0252] [Synthesis Example 2-3] Synthesis of Polymer 3 In a 2 L flask, 1.4 g of monomer 1, 3.9 g of 1-(cyclopentyl-1-yl)-1-methylethyl methacrylate, 5.9 g of 3-fluoro-4-(methylcyclohexyloxy)styrene, 6.0 g of 3-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. The reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 3. The composition of Polymer 3 was 13 C-NMR, and 1 Mw and Mw / Mn were confirmed by GPC using H-NMR. [Chemical formula]

[0253] [Synthesis Example 2-4] Synthesis of Polymer 4 In a 2 L flask, 2.1 g of monomer 2, 7.9 g of 1-methyl-1-cyclopentyl methacrylate, 5.5 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. The reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 4. The composition of Polymer 4 was 13 C-NMR, and 1 Mw and Mw / Mn were confirmed by GPC using H-NMR. [Chemical formula]

[0254] [Synthesis Example 2-5] Synthesis of Polymer 5 1.7 g of monomer 3, 7.9 g of 1-vinyl-1-cyclopentyl methacrylate, 6.0 g of 3-hydroxystyrene, and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 5. The composition of Polymer 5 was 13 confirmed by 13C-NMR and 1 1H-NMR, and Mw and Mw / Mn were confirmed by GPC. [Chemical Formula]

[0255] [Synthesis Example 2-6] Synthesis of Polymer 6 1.4 g of monomer 1, 8.9 g of ALG monomer 1, 6.6 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 6. The composition of Polymer 6 was 13 confirmed by 13C-NMR and 1 1H-NMR, and Mw and Mw / Mn were confirmed by GPC. [Chemical Formula]

[0256] [Synthesis Example 2-7] Synthesis of Polymer 7 Into a 2 L flask, 2.0 g of monomer 4, 7.9 g of 1-methyl-1-cyclopentyl methacrylate, 6.0 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain polymer 7. The composition of polymer 7 was 13 determined by 1 13C-NMR, and [Chemical formula]

[0257] [Synthesis Example 2-8] Synthesis of Polymer 8 Into a 2 L flask, 1.4 g of monomer 1, 8.2 g of ALG monomer 2, 6.6 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain polymer 8. The composition of polymer 8 was 13 determined by 1 13C-NMR, and [Chemical formula]

[0258] [Synthesis Example 2-9] Synthesis of Polymer 9 1.4 g of monomer 1, 7.8 g of tert-butyl methacrylate, 4.8 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 9. The composition of Polymer 9 was 13 determined by 1 C-NMR and [Chemical formula]

[0259] [Synthesis Example 2-10] Synthesis of Polymer 10 2.2 g of monomer 1, 7.9 g of ALG monomer 3, 4.8 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the mixture was reacted for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 10. The composition of Polymer 10 was 13 determined by 1 C-NMR and [Chemical formula]

[0260] [Synthesis Example 2-11] Synthesis of Polymer 11 Into a 2 L flask, 2.2 g of monomer 1, 9.1 g of ALG monomer 4, 6.0 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming up to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the reaction was carried out for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain polymer 11. The composition of polymer 11 was 13 determined by 1 13C-NMR and [Chemical formula]

[0261] [Synthesis Example 2-12] Synthesis of Polymer 12 Into a 2 L flask, 1.4 g of monomer 1, 8.9 g of ALG monomer 5, 6.6 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming up to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the reaction was carried out for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain polymer 12. The composition of polymer 12 was 13 determined by 13C-NMR and 1 1H-NMR. Mw and Mw / Mn were confirmed by GPC. [Chemical formula]

[0262] [Synthesis Example 2-13] Synthesis of Polymer 13 1.4 g of Monomer 1, 10.6 g of ALG Monomer 6, 3.2 g of F Monomer 1, 5.4 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added to a 2 L flask. The reaction vessel was cooled to -70 °C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN was added as a polymerization initiator, the temperature was raised to 60 °C, and the reaction was carried out for 15 hours. This reaction solution was added to 1 L of isopropyl alcohol, and the precipitated white solid was filtered off. The obtained white solid was dried under reduced pressure at 60 °C to obtain Polymer 13. The composition of Polymer 13 was 13 C-NMR and 1 H-NMR, and Mw and Mw / Mn were confirmed by GPC. [Chemical formula]

[0263] [Comparative Synthesis Example 1] Synthesis of Comparative Polymer 1 Comparative Polymer 1 was obtained in the same manner as in Synthesis Examples 2-4, except that Monomer 2 was not used. The composition of Comparative Polymer 1 was 13 C-NMR, and 1 H-NMR, and Mw and Mw / Mn were confirmed by GPC. [Chemical formula]

[0264] [Comparative Synthesis Example 2] Synthesis of Comparative Polymer 2 Comparative Polymer 2 was obtained in the same manner as in Synthesis Examples 2-4, except that Comparative Monomer 1 was used instead of Monomer 2. The composition of Comparative Polymer 2 was 13 C-NMR, and 1 H-NMR, and Mw and Mw / Mn were confirmed by GPC. [Chemical formula]

[0265] [3] Preparation and Evaluation of Positive Resist Material [Examples 1-21, Comparative Examples 1, 2] (1) Preparation of Positive Resist Material A solution in which each component was dissolved in the composition shown in Table 1 was filtered through a 0.2-μm size filter in an organic solvent in which 50 ppm of Polyfox 636, a surfactant manufactured by Omnova, was dissolved to prepare a positive resist material.

[0266] In Table 1, each component is as follows. · Organic solvent: PGMEA (propylene glycol monomethyl ether acetate), DAA (diacetone alcohol)

[0267] · Acid generator: PAG-1 to PAG-12 · Quencher: Q-1 to Q-8

[0268] [Chemical formula]

[0269] [Chemical formula]

[0270] [Chemical formula]

[0271] (2) EUV Lithography Evaluation Each resist material shown in Table 1 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed with a film thickness of 20 nm, and prebaked at 100 °C for 60 seconds using a hot plate to prepare a resist film with a film thickness of 50 nm. This was exposed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a wafer size pitch of 46 nm and a +20% bias) manufactured by ASML, PEB was performed at the temperature shown in Table 1 for 60 seconds on a hot plate, and development was performed with a 2.38% by mass aqueous TMAH solution for 30 seconds to obtain a hole pattern with a dimension of 23 nm. The exposure dose was measured when the hole sizes were each formed to be 23 nm, and this was defined as the sensitivity. Also, the sizes of 50 holes were measured using a length-measuring SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the triple value (3σ) of the standard deviation (σ) calculated from the results was determined as the dimension variation (CDU). The results are also shown in Table 1.

[0272]

Table 1

[0273] From the results shown in Table 1, when using the positive resist material of the present invention containing a base polymer including a repeating unit in which hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond, and an acid generator, it was highly sensitive and had good CDU.

[0274] Note that the present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and any configuration that has a configuration substantially the same as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A positive resist material comprising a base polymer containing a repeating unit in which hydrogen atoms of two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond, and an acid generator, wherein the repeating unit in which hydrogen atoms of the two carboxy groups are each substituted with two tertiary carbons bonded to a double bond or a triple bond is represented by repeating unit a in the following formula (1), and the acid generator is a sulfonium salt of a sulfonic acid containing an aromatic ring substituted with an iodine atom, or an iodonium salt. A positive resist material characterized by the above. 【Chemical 1】 [In the formula, R Ａ is the same or different and is a hydrogen atom or a methyl group. X １ , X ３ is a single bond, a phenylene group, or a linking group having 1 to 12 carbon atoms containing at least one selected from an ester bond, an ether bond, and a lactone ring, provided that it is not the following formula (1'). R １ to R ４ are linear, branched, or cyclic alkyl groups having 1 to 8 carbon atoms, and R １ and R ２ , R ３ and R ４ may combine to form a ring. X ２ is a vinylene group or an ethynylene group.] 【Chemical Formula 2】 (In the formula, the oxygen atom is bonded to the carbon atom of the carboxy group in the above formula (1). The dashed line represents a bond.)

2. The positive resist material according to claim 1, wherein the sulfonium salt of a sulfonic acid containing an aromatic ring substituted with an iodine atom, or the iodonium salt is represented by the following formula (2-1) or (2-2). 【Chemical Formula 3】 In formulas (2-1) and (2-2), p is an integer satisfying 1 ≦ p ≦ 3, q and r are integers satisfying 1 ≦ q ≦ 5, 0 ≦ r ≦ 3, and 1 ≦ q + r ≦ 5. L １１ is a linear, branched, or cyclic saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain a single bond, an ether bond, or an ester bond. L １２ is a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and is a trivalent or tetravalent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, a nitrogen atom, a chlorine atom, a bromine atom, or an iodine atom. R ４０１ is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, or a saturated hydrocarbyl group having 1 to 20 carbon atoms which may contain an ether bond, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, or -NR ４０１Ａ -C(=O)-R ４０１Ｂ or -NR ４０１Ａ -C(=O)-O-R ４０１Ｂ wherein. R ４０１Ａ is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. R ４０１Ｂ is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When p and / or r is 2 or more, each R ４０１ may be the same as or different from each other. Rf １１ ~Rf １４ is each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of these is a fluorine atom or a trifluoromethyl group, and Rf １１ and Rf １２ may combine to form a carbonyl group. R ４０２ 、R ４０３ 、R ４０４ 、R ４０５ 、and R ４０６ is each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Also, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone group, a sulfone group, or a sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate group, or a sulfonic acid ester bond. Also, R ４０２ and R ４０３ may combine with each other to form a ring together with the sulfur atom to which they are attached. ]

3. The positive resist material according to claim 1 or claim 2, wherein the base polymer further contains at least one selected from a repeating unit in which a hydrogen atom of a carboxy group is substituted with a first acid-labile group other than the two tertiary carbons bonded to the double bond or the triple bond, and a repeating unit in which a hydrogen atom of a phenolic hydroxy group is substituted with a second acid-labile group.

4. The positive resist material according to claim 3, wherein the repeating unit substituted with the first acid-labile group is a repeating unit represented by the following formula (b1), and the repeating unit substituted with the second acid-labile group is a repeating unit represented by the following formula (b2). 【Chemical Formula 4】 (wherein R Ａ is independently a hydrogen atom or a methyl group. Y １ is a single bond, a phenylene group or a naphthylene group, or a linking group having 1 to 14 carbon atoms containing at least one selected from an ester bond, an ether bond and a lactone ring. Y ２ is a single bond, an ester bond or an amide bond. Y ３ is a single bond, an ether bond or an ester bond. R １１ is a first acid labile group other than two tertiary carbons each bonded to a double bond or a triple bond. R １２ is a second acid labile group. R １３ is a fluorine atom, a trifluoromethyl group, a cyano group or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R １４ is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a part of its carbon atoms may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. However, 1 ≦ a + b ≦ 5.)

5. The positive resist material according to claim 1 or claim 2, wherein the base polymer further contains a repeating unit containing an adhesion group selected from a hydroxy group, a carboxy group, a lactone ring, a carbonate group, a thiocarbonate group, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonic acid ester bond, a cyano group, an amide bond, -O-C(=O)-S- and -O-C(=O)-NH-.

6. The positive resist material according to claim 1 or claim 2, further comprising at least one selected from an organic solvent, a quencher, and a surfactant.

7. A step of forming a resist film on a substrate using the positive resist material according to claim 1 or claim 2, a step of exposing the resist film to high-energy rays, and a step of developing the exposed resist film using a developer, wherein the pattern forming method is characterized by including these steps.

8. The pattern forming method according to claim 7, wherein the high-energy rays are i-line, KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet rays having a wavelength of 3 to 15 nm.

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