Photoresist compositions and pattern formation methods

Abstract

To provide photoresist compositions and pattern formation methods.SOLUTION: A photoresist composition comprises: an acid-sensitive polymer that comprises a repeat unit comprising an ester acetal group, the acid-sensitive polymer free of a tertiary alkyl ester group and substantially free of an aromatic group; a substance comprising a base-labile group; a fluorine-free photoacid generator compound that generates an acid with -2 or more pKa, wherein the photoresist composition is free of a photoacid generator that generates an acid with less than -2 pKa; and a solvent. The photoresist composition and a pattern formation method using the photoresist composition find specific applications in the formation of fine lithography patterns in the semiconductor manufacturing industry.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates generally to the manufacture of electronic devices. More specifically, the present invention relates to photoresist compositions and patterning methods using such compositions. The compositions and methods find particular use in the formation of lithographic patterns useful in the manufacture of semiconductor devices. [Background technology]

[0002] In the semiconductor manufacturing industry, photoresist layers are used to transfer images into one or more underlying layers, such as metal, semiconductor, or dielectric layers, disposed on a semiconductor substrate, as well as into the substrate itself. To increase the integration density of semiconductor devices and enable the formation of structures having dimensions in the nanometer range, photoresist compositions and photolithography processing tools with high-resolution capabilities have been and continue to be developed.

[0003] Chemically amplified photoresist compositions are traditionally used for high-resolution processing. Such compositions typically utilize a polymer with acid-labile groups, a photoacid generator (PAG), and a solvent. When a layer formed from such a photoresist composition is patternwise exposed to activating radiation, the acid generator forms an acid, which cleaves the acid-labile groups in the exposed regions of the photoresist layer during post-exposure bake. This results in a difference in solubility characteristics between the exposed and unexposed regions of the layer in a developer solution. In a positive-tone development (PTD) process, the exposed regions of the photoresist layer become soluble in an aqueous base developer and are removed from the substrate surface, while the unexposed regions, which are insoluble in the developer, remain after development, forming a positive image. The resulting relief image allows for selective processing of the substrate.

[0004] One approach to achieving nanometer-scale features in semiconductor devices is to use short wavelengths, e.g., 193 nm or shorter, during exposure of chemically amplified photoresists. To further improve lithographic performance, immersion lithography tools have been developed, such as immersion scanners with ArF (193 nm) light sources, which effectively increase the numerical aperture (NA) of the imaging device's lens. This is achieved by using a fluid with a relatively high refractive index, typically water, between the final surface of the imaging device and the top surface of the photoresist-coated semiconductor wafer. ArF immersion tools are currently pushing the limits of lithography up to the 16 nm and 14 nm nodes by using multiple (dual or higher order) patterning. However, with increasing lithographic resolution, the linewidth roughness (LWR) of photoresist patterns has become increasingly important in creating high-resolution patterns. For example, excessive linewidth variation along the length of a gate can adversely affect threshold voltage and increase leakage current, both of which can adversely affect device performance and yield. Therefore, photoresist compositions that enable desirable LWR characteristics would be desirable.

[0005] Advanced ArF photoresist compositions typically contain a polymer with tertiary alkyl ester groups and an ionic PAG compound that generates superacid during post-exposure bake. Because peracids have relatively high activation energies, they are typically required to efficiently cleave the tertiary alkyl ester groups in the exposed regions of the photoresist layer under typical processing conditions. Such PAGs are typically onium salts containing fluorinated alkylsulfonate anions to achieve the superacidity of the conjugate acid. However, the semiconductor industry desires to replace certain fluorinated PAGs with more environmentally friendly alternatives. Furthermore, from a technical standpoint, the fluorinated chains on the PAG typically impart hydrophobic properties (low surface energy) to the PAG, which can result in non-uniform distribution of the PAG throughout the photoresist layer. This can severely impact the pattern fidelity of the resulting photoresist pattern. Summary of the Invention [Problem to be solved by the invention]

[0006] Thus, there is a need in the art for improved photoresist compositions and patterning methods that address one or more of the problems associated with the prior art. [Means for solving the problem]

[0007] According to a first aspect of the present invention, there is provided a photoresist composition comprising: an acid-sensitive polymer having repeat units containing an ester acetal group, the acid-sensitive polymer being free of tertiary alkyl ester groups and substantially free of aromatic groups; a material containing a base-labile group; a fluorine-free photoacid generator compound that generates an acid with a pKa of −2 or greater, the photoresist composition not including photoacid generators that generate acids with a pKa of less than −2; and a solvent.

[0008] Also provided is a patterning method that includes (a) applying a layer of the photoresist composition described herein on a substrate; (b) patternwise exposing the photoresist composition layer to activating radiation; and (c) developing the exposed photoresist composition layer to provide a resist relief image.

[0009] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms "a," "an," and "the" are intended to include both the singular and the plural unless the context dictates otherwise. All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. When an element is said to be "on" or "across" another element, it may be in direct contact with the other element, or intervening elements may be present between them. In contrast, when an element is said to be "directly on" another element, there are no intervening elements present.

[0010] As used herein, "acid labile group" refers to a group that is formed on a polymer and, optionally and typically, has a site that is cleaved from the polymer when the bond is cleaved by the action of an acid, optionally and typically accompanied by heat treatment, to generate a polar group such as a carboxylic acid group or an alcohol group. Acid labile groups include, for example, tertiary alkyl ester groups and acetal groups. Acid labile groups are also commonly referred to in the art as "acid cleavable groups," "acid cleavable protecting groups," "acid decomposable groups," "acid labile protecting groups," "acid leaving groups," and "acid sensitive groups."

[0011] Unless otherwise specified, a "substituted" group means that one or more of its hydrogen atoms has been replaced by one or more substituents. Exemplary substituents include, but are not limited to, hydroxy (-OH), halogen (e.g., -F, -Cl, -I, -Br), C 1~18 Alkyl, C 1~8 Haloalkyl, C 3~12 Cycloalkyl, C with at least one aromatic ring 6~12 Aryl (e.g., phenyl, biphenyl, naphthyl, etc., where each ring is either substituted or unsubstituted aromatic), C having at least one aromatic ring 7~19 Aryl alkyl, C 7~12 Alkyl, alkyl, aryl, and combinations thereof are included. For purposes of determining carbon number, if a group is substituted, the number of carbon atoms in the group is the total number of carbon atoms in such group, excluding the carbon atoms of any substituents. DETAILED DESCRIPTION OF THE INVENTION

[0012] The photoresist composition of the present invention comprises: an acid-sensitive polymer having repeating units containing an ester acetal group, the acid-sensitive polymer being free of tertiary alkyl ester groups and being substantially free of aromatic groups; a material containing a base-labile group; a fluorine-free photoacid generator compound that generates an acid having a pKa of -2 or greater, the photoresist composition being free of photoacid generators that generate acids having a pKa of less than -2; and a solvent. The present inventors have surprisingly discovered that certain photoresist compositions of the present invention can achieve significantly improved lithographic performance, such as reduced linewidth roughness (LWR) and improved photosensitivity. As used herein, "substantially free of aromatic groups" means containing less than 15 mol%, preferably less than 10 mol%, less than 5 mol%, less than 2 mol%, or being completely free of aromatic groups.

[0013] The acid-sensitive polymer comprises repeating units containing ester acetal groups which, upon photoacid-catalyzed decomposition, form carboxylic acid groups on the polymer. The ester acetal groups are preferably represented by the formula (1): -C(O)OC(R 1 )2OR 2 (1) (In the formula, R 1 are independently hydrogen, fluorine, C 1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl, C 2~20 , monocyclic or polycyclic C 3~20 Cycloalkenyl, monocyclic or polycyclic C 6~20 Aryl or monocyclic or polycyclic C 2~20 Heteroaryl, preferably hydrogen, C 1~6 Alkyl or monocyclic or polycyclic C 3~10 cycloalkyl, each of which, except for hydrogen and fluorine, is substituted or unsubstituted; 1 optionally includes as part of its structure one or more groups selected from —O—, —C(O)—, —C(O)—O— or —S—, and R 1 groups, together optionally form a ring; and R 2 is C1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl, C 2~20 Alkenyl, monocyclic or polycyclic C 3~20 Cycloalkenyl, monocyclic or polycyclic C 6~20 Aryl or monocyclic or polycyclic C 2~20 Heteroaryl, preferably C 1~6 Alkyl or monocyclic or polycyclic C 3~10 cycloalkyl, each of which is substituted or unsubstituted; R 2 optionally includes as part of its structure one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S-, and one R 1 is R 2 together with, optionally forming a ring It is of the type.

[0014] In some embodiments, the repeating unit containing the ester acetal group is formed from a monomer containing a carbon-carbon unsaturated vinyl group. As used herein, "carbon-carbon unsaturated vinyl group" refers to a vinyl-containing polymerizable group, typically a substituted or unsubstituted C 2~20 It can be selected from alkenyl, substituted or unsubstituted norbornyl, substituted or unsubstituted (meth)acrylic, substituted or unsubstituted vinyl ether, substituted or unsubstituted vinyl ketone, substituted or unsubstituted vinyl ester, or substituted or unsubstituted vinyl aromatic, and preferably selected from a substituted or unsubstituted norbornyl group or a substituted or unsubstituted (meth)acrylic group.

[0015] The repeating unit containing an ester acetal group is, for example, a repeating unit represented by formula (2): [ka] It can be derived from the monomers

[0016] In equation (2), R 1 and R 2 is as defined in equation (1) above. X ais a polymerizable group that may contain a carbon-carbon unsaturated vinyl group; L 1 is a single bond or a substituted or unsubstituted C 1~10 Alkylene, substituted or unsubstituted C 3~10 Cycloalkylene, substituted or unsubstituted C 3~10 Heterocycloalkylene, substituted or unsubstituted C 6~12 Arylene, substituted or unsubstituted C 3~12 a divalent linking group selected from heteroarylene, or a combination thereof;

[0017] The repeat unit containing an ester acetal group preferably has the formula (2a): [ka] It is derived from the monomer.

[0018] In formula (2a), R 1 and R 2 is as defined in equation (1) above. R a is hydrogen or a substituted or unsubstituted C 1~10 Typically, R a is hydrogen or methyl.

[0019] Exemplary suitable monomers for forming repeat units containing ester acetal groups include: [ka] [ka] [ka] (In the formula, R c is hydrogen or a substituted or unsubstituted C 1~10 alkyl and R is C 1~6 Alkyl, typically C 1~4 Alkyl or C 1~2 alkyl) Examples include:

[0020] The photoresist composition comprises a compound of Formula (3): [ka] In addition, or instead, the repeating unit may contain an ester acetal group derived from a monomer of formula (3): e and R f are each independently hydrogen or a substituted or unsubstituted C 1~10 Preferably, R e and R f are each independently hydrogen or a substituted or unsubstituted C 1~5 alkyl, typically methyl. 13 , R 14 , R 15 and R 16 are each independently hydrogen, fluorine, or C 1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl, C 2~20 Alkenyl, monocyclic or polycyclic C 3~20 Cycloalkenyl, monocyclic or polycyclic C 6~20 Aryl or monocyclic or polycyclic C 2~20 Heteroaryl, preferably hydrogen, C 1~6 Alkyl or monocyclic or polycyclic C 3~10 Cycloalkyl, each of which, except for hydrogen and fluorine, is substituted or unsubstituted, and each may optionally include as part of its structure one or more groups selected from -O-, -C(O)-, -C(O)-O-, or -S-. R 13 and R 14 may optionally form a ring together via a single bond or a divalent linking group. The ring, if formed, may be monocyclic, non-fused polycyclic, or fused polycyclic, and is typically monocyclic. 15 and R 16 may optionally form a ring together via a single bond or a divalent linking group. When a ring is formed, it may be monocyclic, non-fused polycyclic, or fused polycyclic, and is typically monocyclic. Z is a divalent linking group. Preferably, Z is a substituted or unsubstituted C1~8 Alkylene, substituted or unsubstituted C 3~8 Cycloalkylene or substituted or unsubstituted C 3~8 Heterocycloalkylene, substituted or unsubstituted C 6~12 Arylene or substituted or unsubstituted C 3~12 It is heteroarylene and may optionally include as part of its structure one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S-.

[0021] Exemplary suitable monomers of formula (3) include: [ka]

[0022] The acid-sensitive polymer comprises repeat units containing ester acetal groups in a total amount of 1 to 50 mol %, typically 1 to 40 mol %, more typically 5 to 30 mol %, based on the total number of moles of repeat units in the polymer.

[0023] Acid-sensitive polymers typically contain one or more additional repeating units. The additional units can be selected to adjust the properties of the photoresist composition or a layer formed therefrom, such as solubility in a formulation solvent or developer, or to enhance etch resistance. Exemplary additional units can be formed from monomer types including one or more of (meth)acrylate, vinyl ether, vinyl ketone, or vinyl ester, with (meth)acrylate being typical. Such additional units can include, for example, a functional group selected from a lactone group and a base-solubilizing group. When present in the acid-sensitive polymer, the one or more additional repeating units can be used in an amount of up to 90 mol %, typically 3 to 50 mol %, based on the total repeating units of the acid-sensitive polymer.

[0024] Suitable repeat units containing a lactone group may be derived, for example, from monomers of formula (4): [ka]

[0025] In equation (4), R 11 is hydrogen, fluorine, cyano, substituted or unsubstituted C 1~10 Alkyl or substituted or unsubstituted C 1~10 Preferably, R 11 is hydrogen, fluorine, or substituted or unsubstituted C 1~5 It is alkyl, typically methyl. 4 is a single bond or a substituted or unsubstituted C 1~30 Alkylene, substituted or unsubstituted C 1~30 Heteroalkylene, substituted or unsubstituted C 3~30 Cycloalkylene, substituted or unsubstituted C 1~30 Heterocycloalkylene, substituted or unsubstituted C 6~30 Arylene, substituted or unsubstituted C 7~30 Aryl alkylene, or substituted or unsubstituted C 1~30 Heteroarylene, or substituted or unsubstituted C 3~30 and a divalent linking group containing one or more heteroarylalkylenes, wherein L 4 is optionally substituted with, for example, -O-, -C(O)-, -C(O)-O-, -S-, -S(O)2-, and -N(R 44 )—S(O)—, and R 44 is hydrogen, linear or branched C 1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl or monocyclic or polycyclic C 3~20 R can be heterocycloalkyl. 12 is a lactone-containing group, such as a monocyclic, polycyclic or fused polycyclic C 4~20 It is a lactone-containing group.

[0026] Non-limiting examples of monomers of formula (4) include: [ka] (In the formula, R 11 are as described herein) Examples include:

[0027] Additional exemplary lactone-containing monomers include those of formula (5): [ka] (Each R 4 are independently hydrogen or C 1~3 alkyl) Suitable exemplary monomers of formula (2) include: [ka]

[0028] When present in the acid-sensitive polymer, the content of lactone repeat units is typically 5 to 60 mol %, typically 20 to 55 mol % or 25 to 50 mol %, based on the total repeat units in the acid-sensitive polymer.

[0029] The acid-sensitive polymer may comprise a base-soluble repeat unit having a pKa of less than or equal to 12. For example, the base-soluble repeat unit may be derived from a monomer of formula (6). [ka]

[0030] In equation (6), R 13 is hydrogen, substituted or unsubstituted C 1~10 Alkyl or substituted or unsubstituted C 1~10 Preferably, R 13 is hydrogen, fluorine, or substituted or unsubstituted C 1~5 Alkyl, typically methyl. Q 1 is a substituted or unsubstituted C 1~30 Alkylene, substituted or unsubstituted C 3~30 Cycloalkylene, substituted or unsubstituted C 1~30 Heterocycloalkylene, substituted or unsubstituted C 6~30 Arylene, substituted or unsubstituted divalent C7~30 Aryl alkyl, substituted or unsubstituted C 1~30 Heteroarylene or substituted or unsubstituted divalent C 3~30 W can be one or more of heteroarylalkyl or -C(O)-O. W is a base-solubilizing group and can be selected, for example, from: a fluorinated alcohol such as -C(CF)OH; an amide; an imide; or -NHS(O)Y 1 and -C(O)NHC(O)Y 1 (In the formula, Y 1 is C 1~4 (It is a perfluoroalkyl or fluoroalcohol group.) In formula (4), c is an integer of 1 to 3.

[0031] Non-limiting examples of monomers of formula (6) include: [ka] (In the formula, R 13 and Y 1 is as above) Examples include:

[0032] When present, the base-soluble repeat units may typically be present in the acid-sensitive polymer in an amount of from 2 to 75 mol %, typically from 5 to 25 mol %, more typically from 5 to 15 mol %, based on the total repeat units of the acid-sensitive polymer.

[0033] Suitable acid-sensitive polymers include, for example: [ka] (wherein a, b, c, and d each represent the mole percent of the associated repeat unit based on 100 mole percent of all repeat units in the polymer). Examples include:

[0034] The weight average molecular weight (M wThe PDI of the polymer is typically 1,000 to 50,000 daltons (Da), preferably 2,000 to 30,000 Da, more preferably 3,000 to 20,000 Da, and even more preferably 4,000 to 15,000 Da. The PDI of the polymer is typically 1.1 to 3, more typically 1.1 to 2. The molecular weight is determined by gel permeation chromatography (GPC) using polystyrene standards. The acid-sensitive polymer is typically present in the photoresist composition in an amount of 50 to 95 wt %, more typically 80 to 95 wt %, based on the total solids of the photoresist composition. It will be understood that "total solids" includes the acid-sensitive polymer, PAG, base-labile group-containing material, and other non-solvent components of the photoresist composition.

[0035] Suitable polymers of the present invention can be easily prepared based on and by analogy with the procedures described in the examples of the present application, which will be readily understood by those skilled in the art. For example, one or more monomers corresponding to the repeating units described herein can be combined or separately fed using an appropriate solvent and initiator and polymerized in a reactor. The monomer composition may further include additives such as a solvent, a polymerization initiator, a curing catalyst (i.e., an acid catalyst), etc. For example, a polymer can be obtained by polymerization of each monomer under any suitable conditions, such as heating at an effective temperature, irradiation with activating radiation at an effective wavelength, or a combination thereof. In some embodiments, the monomer composition further includes a curing agent.

[0036] The photoresist composition further comprises a material containing one or more base-labile groups ("base-labile material"). As referred to herein, a base-labile group is a functional group that can undergo a cleavage reaction to provide a polar group, such as a hydroxyl, carboxylic acid, or sulfonic acid, in the presence of an aqueous alkaline developer after the exposure and post-exposure bake steps. The base-labile group does not significantly react (e.g., does not undergo a bond-breaking reaction) before the development step of the photoresist composition containing the base-labile group. Thus, for example, the base-labile group is substantially inert during the pre-exposure soft bake, exposure, and post-exposure bake steps. "Substantially inert" means that 5% or less, typically 1% or less, of the base-labile groups (or sites) decompose, cleave, or react during the pre-exposure soft bake, exposure, and post-exposure bake steps. The base-labile group is reactive under typical photoresist development conditions, for example, using an aqueous alkaline photoresist developer, such as a 0.26N (N) aqueous tetramethylammonium hydroxide (TMAH) solution. For example, a 0.26N aqueous TMAH solution can be used for single puddle development or dynamic development, where the 0.26N TMAH developer is dispensed onto the imaged photoresist layer for a suitable time, such as 10 to 120 seconds (s). An exemplary base-labile group is an ester group, typically a fluorinated ester group. Preferably, the base-labile material is substantially immiscible with the polymer and other solid components of the photoresist composition and has a lower surface energy than these polymers and other solid components. When coated onto a substrate, the base-labile material can thereby separate from the other solid components of the photoresist composition to the top surface of the formed photoresist layer.

[0037] In some embodiments, the base-labile material is a polymeric material, also referred to herein as a base-labile polymer, and the base-labile polymer can include one or more repeating units containing one or more base-labile groups. For example, the base-labile polymer can include repeating units containing two or more base-labile groups, which may be the same or different. Preferred base-labile polymers include at least one repeating unit containing two or more base-labile groups, for example, repeating units containing two or three base-labile groups. The base-labile polymer is typically fluorinated.

[0038] The base labile polymer has the formula (7A): [ka] (In the formula, X e is a carbon-carbon unsaturated vinyl group, L is a divalent linking group, and R n is a substituted or unsubstituted C1-20 fluoroalkyl, provided that the carbon atom bonded to the carbonyl (C=O) in formula (15A) is substituted with at least one fluorine atom. The polymer may comprise repeat units derived from one or more of the monomers.

[0039] Exemplary monomers of formula (7A) include: [ka]

[0040] The base-labile polymer can include repeat units containing two or more base-labile groups. For example, the base-labile polymer can be represented by formula (7B): [ka] (In the formula, X f is a carbon-carbon unsaturated vinyl group; R pis a substituted or unsubstituted C1-20 fluoroalkyl, provided that the carbon atom bonded to the carbonyl (C=O) in formula (15B) is substituted with at least one fluorine atom; L 13 is a polyvalent linking group containing one or more of substituted or unsubstituted C1-20 alkylene, substituted or unsubstituted C3-20 cycloalkylene, -C(O)-, or -C(O)O-; n4 can be an integer of 2 or greater, for example, 2 or 3. It may contain repeat units derived from one or more monomers of

[0041] Exemplary monomers of formula (7B) include: [ka]

[0042] The base-labile polymer can include repeat units that include one or more base-labile groups. For example, the base-labile polymer can be represented by formula (7C): [ka] (In the formula, X g and R q are X e and R n is as defined in formula (15A); L 14 is a divalent linking group; L 15 is a substituted or unsubstituted C1-20 fluoroalkylene, and the carbon atom bonded to the carbonyl (C=O) in formula (7C) is substituted with at least one fluorine atom. It may contain repeat units derived from one or more monomers of

[0043] Exemplary monomers of formula (7C) include: [ka]

[0044] In some embodiments, the base-labile polymer can include one or more base-labile groups and one or more acid-labile groups, such as one or more acid-labile ester moieties (e.g., t-butyl esters) or acid-labile acetal groups. For example, the base-labile polymer can include a repeating unit that includes a base-labile group and an acid-labile group, i.e., a repeating unit in which both the base-labile group and the acid-labile group are present in the same repeating unit. In another example, the base-labile polymer can include a first repeating unit that includes a base-labile group and a second repeating unit that includes an acid-labile group. Preferred photoresists of the present invention can reduce defects associated with resist relief images formed from photoresist compositions.

[0045] The base-labile polymer can be prepared using any suitable method in the art, including those described herein for the first and second polymers. For example, the base-labile polymer can be obtained by polymerization of the respective monomers under any suitable conditions, such as heating at an effective temperature, irradiating with actinic radiation at an effective wavelength, or a combination thereof. Additionally or alternatively, one or more base-labile groups can be grafted onto the backbone of the polymer using a suitable method.

[0046] In some embodiments, the base-labile substance is a single molecule containing one or more base-labile ester groups, preferably one or more fluorinated ester groups. Single-molecule base-labile substances typically have a MW in the range of 50 to 1,500 Da. Exemplary base-labile substances include: [ka]

[0047] Typically, the base-labile material is present in the photoresist composition in an amount of from 1 to 10 weight percent, more typically from 3 to 9 weight percent, based on the total solids content of the photoresist composition.

[0048] The photoresist composition includes a fluorine-free acid generator (PAG) compound that generates an acid with a pKa of -2 or greater, e.g., -2 to 3. The acid generated by the PAG must be strong enough to cause deprotection of acid-labile groups on the polymer during photoresist processing, typically during post-exposure bake. The PAG is typically in a non-polymeric form, but can also be in a polymeric form, for example, present in the polymerized repeat unit of an acid-sensitive polymer or as part of a different polymer. Suitable PAGs are capable of generating an acid that causes decomposition of acid-labile ester acetal groups present on the photoresist polymer in the exposed regions of the photoresist layer during post-exposure bake.

[0049] Particularly suitable PAGs are of formula G + A - is ionic, and G + is an organic cation, and A - is an organic anion, the conjugate acid of which has a pKa of -2 or greater, e.g., -2 to 3. Organic cations include, for example, iodonium cations substituted with two alkyl groups, aryl groups, or a combination of alkyl and aryl groups; and sulfonium cations substituted with three alkyl groups, aryl groups, or a combination of alkyl and aryl groups. In some embodiments, G + is an iodonium cation substituted with two alkyl groups, aryl groups, or a combination of alkyl and aryl groups; or a sulfonium cation substituted with three alkyl groups, aryl groups, or a combination of alkyl and aryl groups. In some embodiments, G + is a substituted sulfonium cation having the formula (8A) or an iodonium cation having the formula (8B): [ka] (In the formula, each R aa independently, C 1~20 Alkyl group, C 1~20 Fluoroalkyl group, C 3~20 Cycloalkyl groups, C 3~20 Fluorocycloalkyl groups, C2~20 Alkenyl group, C 2~20 Fluoroalkenyl group, C 6~30 Aryl group, C 6~30 Fluoroaryl group, C 6~30 Iodoaryl group, C 4~30 Heteroaryl groups, C 7~20 Arylalkyl groups, C 7~20 Fluoroarylalkyl groups, C 5~30 Heteroarylalkyl group or C 5~30 fluoroheteroarylalkyl groups, each of which is substituted or unsubstituted; and each R aa is another R aa The group is separate from the group or is linked to the group via a single bond or a divalent linking group to form a ring. Each R aa has -O-, -C(O)-, -C(O)-O-, -C 1~12 Hydrocarbylene-, -O-(C 1~12 hydrocarbylene)-, -C(O)-O-(C 1~12 hydrocarbylene)- and -C(O)-O-(C 1~12 Each R may optionally include one or more groups selected from aa R may independently optionally include an acid labile group selected from, for example, a tertiary alkyl ester group, a secondary or tertiary aryl ester group, a secondary or tertiary ester group having a combination of alkyl and aryl groups, a tertiary alkoxy group, an acetal group, or a ketal group. aa Divalent linking groups suitable for linking groups include, for example, -O-, -S-, -Te-, -Se-, -C(O)-, -C(S)-, -C(Te)- or -C(Se)-, substituted or unsubstituted C 1~5 alkylene and combinations thereof.

[0050] Exemplary sulfonium cations of formula (8A) include: [ka] [ka]

[0051] Exemplary iodonium cations of formula (8B) include: [ka]

[0052] Suitable onium salt PAG anions include, for example, groups selected from sulfonate and sulfonyl groups. Suitable sulfonate anions include both fluorine-free aromatic and non-aromatic sulfonates. Exemplary suitable anions having a sulfonate group include: [ka]

[0053] The photoresist composition can optionally contain multiple PAGs. Typically, the photoacid generator is present in the photoresist composition in an amount from 3 to 65 weight percent, more typically from 5 to 55 weight percent, and even more typically from 8 to 30 weight percent, based on the total solids content of the photoresist composition.

[0054] The photoresist composition further comprises a solvent for dissolving the components of the composition and facilitating its coating on a substrate. Preferably, the solvent is an organic solvent conventionally used in the manufacture of electronic devices. Suitable solvents include, for example, aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and 1-chlorohexane; alcohols such as methanol, ethanol, 1-propanol, isopropanol, tert-butanol, 2-methyl-2-butanol, and 4-methyl-2-pentanol; ethers such as propylene glycol monomethyl ether (PGME), diethyl ether, tetrahydrofuran, 1,4-dioxane, and anisole; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, and cyclohexanone (CHO); ethyl acetate, n- Examples of suitable solvents include esters such as butyl acetate, propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate (EL), hydroxyisobutyric acid methyl ester (HBM), and ethyl acetoacetate; lactones such as γ-butyrolactone (GBL) and ε-caprolactone; lactams such as N-methylpyrrolidone; nitriles such as acetonitrile and propionitrile; cyclic or acyclic carbonate esters such as propylene carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and propylene carbonate; polar aprotic solvents such as dimethyl sulfoxide and dimethylformamide; water; and combinations thereof. Among these, preferred solvents are PGME, PGMEA, EL, GBL, HBM, CHO, and combinations thereof. The total solvent content (i.e., the cumulative solvent content of all solvents) in a photoresist composition is typically 40 to 99 wt %, for example 70 to 99 wt % or 85 to 99 wt %, based on the total weight of the photoresist composition. The desired solvent content will depend, for example, on the desired thickness of the coated photoresist layer and the coating conditions.

[0055] The photoresist composition may further comprise one or more additional optional additives. Such optional additives may include, for example, chemical dyes and contrast agents, anti-striation agents, plasticizers, speed enhancers, sensitizers, photolytic quenchers (also known as photolytic bases), base quenchers, surfactants, and the like, or combinations thereof. When present, optional additives are typically present in the photoresist composition in an amount of 0.01 to 10 weight percent, based on the total solids content of the photoresist composition.

[0056] Photolytic quenchers (PDQs) generate weak acids upon irradiation. The generated acids are not strong enough to decompose ester acetal acid-labile groups on acid-sensitive polymers. Therefore, the generated acids of PDQs are weaker (have a higher pKa) than the acids generated by PAG compounds. Typically, the pKa of the generated acids of PDQs is greater than 3, e.g., 3-6. Exemplary photolytic quenchers include strong acid generator compounds, such as photolytic cations, preferably C1-20 carboxylic acids, but also those useful for preparing strong acid generator compounds paired with anions of weak acids (pKa > 3). Exemplary carboxylic acids include formic acid, acetic acid, propionic acid, tartaric acid, succinic acid, cyclohexanecarboxylic acid, benzoic acid, salicylic acid, etc. In a preferred embodiment, the photolytic quencher is a photolytic organic zwitterionic compound, such as diphenyliodonium-2-carboxylate.

[0057] Exemplary basic quenching agents include, for example, straight-chain aliphatic amines such as tributylamine, trioctylamine, triisopropanolamine, tetrakis(2-hydroxypropyl)ethylenediamine, n-tert-butyldiethanolamine, tris(2-acetoxy-ethyl)amine, 2,2′,2″,2′′-(ethane-1,2-diylbis(azanetriyl))tetraethanol, 2-(dibutylamino)ethanol, and 2,2′,2″-nitrilotriethanol; cyclic aliphatic amines such as 1-(tert-butoxycarbonyl)-4-hydroxypiperidine, tert-butyl 1-pyrrolidinecarboxylate, tert-butyl 2-ethyl-1H-imidazole-1-carboxylate, di-tert-butyl piperazine-1,4-dicarboxylate, and N-(2-acetoxy-ethyl)morpholine; pyridine, di-tert-butylpyridine, and pyridine. linear and cyclic amides and derivatives thereof, such as N,N-bis(2-hydroxyethyl)pivalamide, N,N-diethylacetamide, N1,N1,N3,N3-tetrabutylmalonamide, 1-methylazepan-2-one, 1-allylazepan-2-one, and tert-butyl 1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylcarbamate; ammonium salts, such as quaternary ammonium salts of sulfonates, sulfamates, carboxylates, and phosphonates; imines, such as primary and secondary aldimines and ketimines; optionally substituted diazines, such as pyrazine, piperazine, and phenazine; optionally substituted diazoles, such as pyrazole, thiadiazole, and imidazole; and optionally substituted pyrrolidones, such as 2-pyrrolidone, and cyclohexylpyrrolidine.

[0058] Exemplary surfactants include fluorinated and non-fluorinated surfactants, and may be ionic or non-ionic, with non-ionic surfactants being preferred. Exemplary fluorinated non-ionic surfactants include perfluoro C4 surfactants, such as FC-4430 and FC-4432 surfactants, available from 3M Corporation; and fluorodiols, such as POLYFOX PF-636, PF-6320, PF-656, and PF-6520 fluorosurfactants from Omnova. In one embodiment, the photoresist composition may further include a surfactant polymer comprising a fluorine-containing repeating unit.

[0059] A pattern formation method using the photoresist composition of the present invention is described below. Suitable substrates onto which the photoresist composition can be coated include electronic device substrates. A variety of electronic device substrates, such as semiconductor wafers, polycrystalline silicon substrates, packaging substrates such as multichip modules, flat panel display substrates, and substrates for light-emitting diodes (LEDs) such as organic light-emitting diodes (OLEDs), can be used in the present invention, with semiconductor wafers being typical. Such substrates are typically composed of one or more of silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon germanium, gallium arsenide, aluminum, sapphire, tungsten, titanium, titanium-tungsten, nickel, copper, and gold. Suitable substrates can be in the form of wafers, such as those used in the manufacture of integrated circuits, optical sensors, flat panel displays, optical integrated circuits, and LEDs. Such substrates can be of any suitable size. Typical wafer substrate diameters are 200 to 300 millimeters (mm), although wafers with smaller and larger diameters can be suitably used in accordance with the present invention. The substrate may optionally include one or more layers or structures that may contain the active or operable portions of the device being formed.

[0060] Typically, one or more lithography layers, such as a hard mask layer, e.g., a spin-on carbon (SOC), amorphous carbon, or metal hard mask layer, a CVD layer, such as a silicon nitride (SiN), silicon oxide (SiO), or silicon oxynitride (SiON) layer, an organic or inorganic underlayer, such as a bottom antireflective coating (BARC) layer, or a combination thereof, is provided on the top surface of the substrate before coating with the photoresist composition of the present invention. Such layers, together with an overcoated photoresist layer, form a lithography material stack.

[0061] Optionally, a layer of adhesion promoter can be applied to the substrate surface before coating with the photoresist composition. If an adhesion promoter is desired, any suitable adhesion promoter for polymer films can be used, such as silanes, typically organosilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and hexamethyldisilazane, and aminosilane coupling agents such as gamma-aminopropyltriethoxysilane. Particularly suitable adhesion promoters include those sold under the names AP 3000, AP 8000, and AP 9000S, available from DuPont Electronics & Imaging (Marlborough, Massachusetts).

[0062] The photoresist composition can be coated onto a substrate by any suitable method, such as spin coating, spray coating, dip coating, doctor blading, etc. For example, application of a layer of photoresist can be achieved by spin-coating the photoresist in a solvent using a coating truck, in which the photoresist is dispensed onto a rotating wafer. During dispensing, the wafer is typically rotated at a speed of up to 4,000 revolutions per minute (rpm), e.g., 200 to 3,000 rpm, e.g., 1,000 to 2,500 rpm, for a period of 15 to 120 seconds to obtain a layer of photoresist composition on the substrate. Those skilled in the art will understand that the thickness of the coated layer can be adjusted by varying the rotation speed and / or the solids content of the composition. Photoresist layers formed from the compositions of the present invention typically have a dry layer thickness of 10 to 3,000 nanometers (nm), more typically 15 to 500 nm, 20 to 200 nm, or 50 to 150 nm.

[0063] The photoresist composition is typically then soft-baked to minimize the solvent content in the layer, thereby forming a tack-free coating and improving adhesion of the layer to the substrate. Soft-baking can be performed, for example, on a hot plate or in an oven, with a hot plate being typical. The soft-baking temperature and time depend, for example, on the specific photoresist composition and thickness. The soft-baking temperature is typically 90 to 170°C, e.g., 110 to 150°C. The soft-baking time is typically 10 seconds to 20 minutes, e.g., 1 minute to 10 minutes or 1 minute to 5 minutes. The soft-baking temperature and time can be easily determined by one skilled in the art based on the components of the composition.

[0064] The photoresist layer is then patternwise exposed to activating radiation to create a solubility differential between the exposed and unexposed regions. It may be desirable to include a delay between the soft bake and the exposure. Suitable delay times include, for example, 5 seconds to 30 minutes, or 1 to 5 minutes. References herein to exposing a photoresist composition to radiation that activates the composition indicate that the radiation can form a latent image in the photoresist composition. Exposure is typically carried out through a patterned photomask having optically transparent and optically opaque regions corresponding to the exposed and unexposed regions of the resist layer, respectively. Alternatively, such exposure can be carried out without a photomask, as in direct-write processes typically used for electron beam lithography. Activating radiation typically has a wavelength of less than 400 nm, less than 300 nm, or less than 200 nm, such as wavelengths of 248 nm (KrF), 193 nm (ArF), and 13.5 nm (extreme ultraviolet, EUV), or with electron beam lithography, 193 nm being typical. This method is used in immersion or dry (non-immersion) lithography techniques. Exposure energies are typically between 1 and 200 millijoules per square centimeter (mJ / cm). 2 ), preferably 10 to 100 mJ / cm 2 , more preferably 20 to 50 mJ / cm 2 and depends on the exposure tool and the components of the photoresist composition. In a preferred embodiment, the activating radiation is 193 nm (ArF), with 193 nm immersion lithography being particularly preferred.

[0065] After the photoresist layer is exposed, a post-exposure bake (PEB) of the exposed photoresist layer is performed. Suitable PEB times include, for example, 5 seconds to 30 minutes or 1 to 5 minutes. PEB can be performed, for example, on a hot plate or in an oven, with a hot plate being typical. PEB conditions will depend, for example, on the specific photoresist composition and layer thickness. PEB is typically performed at a temperature of 80 to 150°C for a time of 30 to 120 seconds. A latent image defined by polarity-switched regions (exposed regions) and polarity-unswitched regions (unexposed regions) is formed in the photoresist layer. This polarity switching results from photoacid-catalyzed deprotection of the ester acetal groups of the polymer, resulting in the formation of carboxylic acid groups on the polymer in the exposed regions.

[0066] The exposed photoresist layer is then developed with a suitable developer to selectively remove areas of the layer that are soluble in the developer, while the remaining insoluble areas form the resulting photoresist pattern relief image. In a positive-tone development (PTD) process, the exposed areas of the photoresist layer are removed during development, leaving behind the unexposed areas. Conversely, in a negative-tone development (NTD) process, the exposed areas of the photoresist layer remain, while the unexposed areas are removed during development. Application of the developer can be accomplished by any suitable method, such as those described above with respect to application of the photoresist composition, with spin coating being typical. The development time is effective to remove the soluble areas of the photoresist, typically between 5 and 60 seconds. Development is typically performed at room temperature.

[0067] Suitable developers for the PTD process include aqueous base developers, such as quaternary ammonium hydroxide solutions such as tetramethylammonium hydroxide (TMAH), preferably 0.26N TMAH, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc. Suitable developers for the NTD process are organic solvent-based, meaning that the cumulative content of organic solvent in the developer is 50% by weight or more, typically 95% by weight or more, 95% by weight or more, 98% by weight or more, or 100% by weight, based on the total weight of the developer. Suitable organic solvents for NTD developers include, for example, those selected from ketones, esters, ethers, hydrocarbons, and mixtures thereof. The developer is typically n-butyl acetate or 2-heptanone.

[0068] Coated substrates can be formed from the photoresist compositions of the invention. Such coated substrates include (a) a substrate having one or more layers to be patterned on its surface; and (b) a layer of a photoresist composition over the one or more layers to be patterned.

[0069] The photoresist pattern can be used, for example, as an etch mask, allowing the pattern to be transferred to one or more subsequent underlying layers by known etching techniques, typically dry etching such as reactive ion etching. The photoresist pattern can be used, for example, for pattern transfer to an underlying hard mask layer, which is then used as an etch mask for pattern transfer to one or more layers below the hard mask layer. If the photoresist pattern is not consumed during pattern transfer, it can be removed from the substrate by known techniques, such as oxygen plasma ashing. When used in one or more such pattern formation processes, the photoresist composition can be used to manufacture semiconductor devices such as memory devices, processor chips (CPUs), graphics chips, optoelectronic chips, LEDs, OLEDs, and other electronic devices.

[0070] The present invention can include the following aspects 1 to 10. [Aspect 1] 1. A photoresist composition comprising: an acid-sensitive polymer comprising repeat units comprising ester acetal groups, wherein the acid-sensitive polymer is free of tertiary alkyl ester groups and is substantially free of aromatic groups; a substance containing a base labile group; a fluorine-free photoacid generator compound that generates an acid having a pKa of −2 or greater, wherein the photoresist composition does not contain a photoacid generator that generates an acid having a pKa of less than −2; Solvent and A photoresist composition comprising: [Aspect 2] The ester acetal group is represented by the formula (1): -C(O)OC(R 1 )2OR 2 (1) (In the formula, R 1 are independently hydrogen, fluorine, C 1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl, C 2~20 Alkenyl, monocyclic or polycyclic C 3~20 Cycloalkenyl, monocyclic or polycyclic C 6~20 Aryl or monocyclic or polycyclic C 2~20 heteroaryl, each of which, except for hydrogen and fluorine, is substituted or unsubstituted; and each R 1 optionally includes as part of its structure one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S-, and said R 1 groups, together optionally form a ring; and R 2 is C 1~20 Alkyl, monocyclic or polycyclic C 3~20 Cycloalkyl, C 2~20 Alkenyl, monocyclic or polycyclic C 3~20 Cycloalkenyl, monocyclic or polycyclic C 6~20 Aryl or monocyclic or polycyclic C 2~20 Heteroaryl, preferably C1~6 Alkyl or monocyclic or polycyclic C 3~10 cycloalkyl, each of which is substituted or unsubstituted; R 2 optionally includes as part of its structure one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S-, and one R 1 is R 2 together with, optionally forming a ring 2. The photoresist composition of embodiment 1, wherein [Aspect 3] 3. The photoresist composition of embodiment 1 or 2, wherein the acid-sensitive polymer further comprises a second repeat unit formed from a monomer comprising a lactone group. [Aspect 4] The second repeat unit is represented by formula (5): [ka] (In the formula, R 4 are independently hydrogen or C 1~3 alkyl) 4. The photoresist composition of embodiment 3, formed from a monomer of [Aspect 5] Aspect 5. The photoresist composition of any one of aspects 1 to 4, wherein the acid-sensitive polymer is completely free of aromatic groups. [Aspect 6] Aspect 6. The photoresist composition of any one of aspects 1 to 5, further comprising a photodegradable deactivator. [Aspect 7] Aspect 7. The photoresist composition of any one of aspects 1-6, wherein the material containing base labile groups is a polymer present in the photoresist composition in an amount from 1 to 10 weight percent, based on the total solids content of the photoresist composition. [Aspect 8] Aspect 8. The photoresist composition of any one of aspects 1 to 7, wherein the photoacid generator compound is an onium salt selected from aromatic and non-aromatic sulfonates. [Aspect 9] A pattern formation method, comprising: (a) applying a layer of the photoresist composition of any one of embodiments 1-8 onto a substrate; (b) patternwise exposing the photoresist composition layer to activating radiation; and (c) developing the exposed photoresist composition layer to provide a resist relief image. A pattern forming method comprising: The following non-limiting examples illustrate the present invention. [Example]

[0071] Polymer synthesis The polymers were synthesized using the following monomers according to the procedure described below. [ka]

[0072] Example 1 (Polymer P1) A feed solution was prepared by combining 36.69 g of propylene glycol monomethyl ether acetate (PGMEA), 11.95 g of Monomer M1, 10.92 g of Monomer M2, 7.13 g of Monomer M3, and 1.59 g of Wako V-601 initiator in a vessel and stirring the mixture to dissolve the components. 15.93 g of PGMEA was added to the reaction vessel, and the vessel was purged with nitrogen for 30 minutes. The reaction vessel was then heated to 80°C with stirring. The monomer feed solution was then added to the reaction vessel and fed over 4 hours. The initiator feed solution was then added to the reaction vessel and fed over 3.5 hours. The reaction vessel was maintained at 80°C with stirring for an additional 3 hours. The reaction mixture was then heated at 80°C for an additional 30 minutes and then cooled to room temperature. The polymer was precipitated by adding the reaction mixture dropwise to methanol (10x, v / v), collected by filtration, and dried under vacuum. Polymer P1 was obtained as a white solid powder.

[0073] Examples 2 to 8 (Polymers P2 to P8) Polymers P2 to P8 were synthesized using a procedure similar to that used for polymer P1. The structural units, weight average molecular weight, and polydispersity index (PDI) (Mw / Mn) of each polymer are shown in Tables 1 and 2.

[0074] Example 9 (Polymer AP1) A monomer solution was prepared by combining 192.00 grams (g) of propylene glycol monomethyl ether acetate (PGMEA), 133.2 g of Monomer M9, and 8.51 g of Monomer M2 in a flask and stirring the resulting mixture to dissolve the components. Separately, an initiator solution was prepared by combining 10.72 g of PGMEA and 6.2 g of V601 initiator (Wako Chemical Co., Ltd.) in a flask. 20.05 g of PGMEA was introduced into a reaction vessel, and the vessel was purged with nitrogen for 30 minutes. The reaction vessel was then heated to 95°C with stirring. The monomer solution and initiator solution were then introduced into the reaction vessel as separate feed streams over 2.5 hours. After 2.5 hours, the reaction vessel was maintained at 95°C with stirring for an additional 3 hours, after which it was cooled to room temperature. Polymer AP1 was obtained.

[0075] [Table 1]

[0076] Preparation of the photoresist composition Photoresist compositions were prepared by dissolving the solid components in a solvent using the materials and amounts listed in Table 2. The resulting mixtures, produced on a 30-100 g scale, were shaken on a mechanical shaker for 3-24 hours and then filtered through a PTFE disc filter with a 0.2 micron pore size.

[0077] [Table 2]

[0078] [ka]

[0079] Lithography Evaluation A 300 mm silicon wafer was spin-coated with AR™ 40A antireflective agent (DuPont Electronics & Industrial) for 60 seconds using a cure temperature of 205° C. to form a first BARC layer 800 Å thick. The wafer was then spin-coated with AR™ 104 antireflective agent (DuPont Electronics & Imaging) for 60 seconds using a cure temperature of 175° C. A second BARC layer with a thickness of 400 Å was formed by coating the wafer with the respective photoresist composition shown in Table 3 and soft-baking at 95°C for 60 seconds to obtain a 900 Å thick photoresist layer. The BARC layer and photoresist layer were coated using a TEL Clean Track Lithius coating tool. The wafers were exposed to various doses using a mask with a 1:1 line-space pattern (28 nm linewidth / 56 nm pitch or 45 nm linewidth / 90 nm pitch) using an ASML 1900i immersion scanner (1.35 NA, 0.90 / 0.988 inner / outer sigma, dipole illumination with 35Y polarization). The exposed wafers were post-exposure baked at 80°C for 60 seconds and developed with a 0.26 N aqueous TMAH solution for 12 seconds. The wafers were then rinsed with deionized water and spin-dried to form the photoresist pattern. CD and linewidth measurements of the formed patterns were performed using a Hitachi High Technologies Co. CG4000CD-SEM. Esize, the exposure dose at which the pattern CD equals the mask pattern CD, was also determined. LWR was determined using the 3-sigma value from the distribution of a total of 100 random points in the linewidth measurements. The results are shown in Table 3.

[0080] [Table 3]

Claims

1. an acid-sensitive polymer comprising repeating units comprising an ester acetal group, wherein the acid-sensitive polymer is free of tertiary alkyl ester groups and aromatic groups; a substance containing a base labile group; a fluorine-free photoacid generator compound that generates an acid having a pKa of −2 or greater; Solvent and A photoresist composition comprising: the photoresist composition does not contain a photoacid generator that generates an acid having a pKa of less than −2; The materials containing base labile groups have the formulas (7A), (7B) and (7C): 【Chemical 1】 (In the formula, X ｅ is a carbon-carbon unsaturated vinyl group; L １２ is a divalent linking group; R ｎ is a substituted or unsubstituted C1-20 fluoroalkyl, provided that the carbon atom bonded to the carbonyl (C=O) in formula (7A) is substituted with at least one fluorine atom. 【Chemistry 2】 (In the formula, X ｆ is a carbon-carbon unsaturated vinyl group; R ｐ is a substituted or unsubstituted C1-20 fluoroalkyl, provided that the carbon atom bonded to the carbonyl (C═O) in formula (7B) is substituted with at least one fluorine atom; L １３ is a polyvalent linking group containing one or more of a substituted or unsubstituted C1-20 alkylene, a substituted or unsubstituted C3-20 cycloalkylene, —C(O)—, or —C(O)O—; and n4 is 2 or 3. 【Chemistry 3】 (In the formula, X ｇ and R ｑ are X ｅ and R ｎ is as defined in formula (7A); L １４ is a divalent linking group; L １５ is a substituted or unsubstituted C1-20 fluoroalkylene, and the carbon atom bonded to the carbonyl (C═O) in formula (7C) is substituted with at least one fluorine atom. The photoresist composition is a base-labile polymer comprising repeat units derived from one or more monomers of:

2. The ester acetal group is represented by the formula (1): -C(O)OC(R １ ) ２ OR ２ (1) (In the formula, R １ are independently hydrogen, fluorine, C １～２０ Alkyl, monocyclic or polycyclic C ３～２０ Cycloalkyl, C ２～２０ Alkenyl, monocyclic or polycyclic C ３～２０ Cycloalkenyl, monocyclic or polycyclic C ６～２０ Aryl or monocyclic or polycyclic C ２～２０ heteroaryl, each of which, except for hydrogen and fluorine, is substituted or unsubstituted; １ optionally includes one or more groups selected from —O—, —C(O)—, —C(O)—O—, or —S— as part of its structure, and said R １ groups, together optionally form a ring; and R ２ is C １～２０ Alkyl, monocyclic or polycyclic C ３～２０ Cycloalkyl, C ２～２０ Alkenyl, monocyclic or polycyclic C ３～２０ Cycloalkenyl, monocyclic or polycyclic C ６～２０ Aryl or monocyclic or polycyclic C ２～２０ Heteroaryl, preferably C １～６ Alkyl or monocyclic or polycyclic C ３～１０ cycloalkyl, each of which is substituted or unsubstituted; R ２ optionally includes as part of its structure one or more groups selected from —O—, —C(O)—, —C(O)—O— or —S—, and one R １ is R ２ together with, optionally forming a ring 2. The photoresist composition of claim 1 wherein

3. 3. The photoresist composition of claim 1, wherein the acid-sensitive polymer further comprises a second repeat unit formed from a monomer containing a lactone group.

4. The second repeating unit is represented by formula (5): 【Chemistry 4】 (In the formula, R ４ are independently hydrogen or C １～３ alkyl) 4. The photoresist composition of claim 3 formed from a monomer of the formula:

5. 5. The photoresist composition of any one of claims 1 to 4, wherein the material containing base labile groups is a polymer present in the photoresist composition in an amount of 1 to 10 wt %, based on total solids content of the photoresist composition.

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