Patent Application
20230400765
The present disclosure relates to a radiation-sensitive resin composition, a method for forming a pattern, and an onium salt compound.
A photolithography technology using a resist composition has been used for the fine circuit formation in a semiconductor device. As the representative procedure, for example, a resist pattern is formed on a substrate by generating an acid by irradiating the coating of the resist composition with a radioactive ray through a mask pattern, and then reacting in the presence of the acid as a catalyst to generate the difference of solubility of a resin into an alkaline or organic developer between an exposed part and a non-exposed part.
In the photolithography technique, the micronization of the pattern is promoted by using a short-wavelength radioactive ray such as an ArF excimer laser or by using an immersion exposure method (liquid immersion lithography) in which exposure is performed in a state in which a space between a lens of an exposure apparatus and a resist film is filled with a liquid medium.
While efforts for further technological development are in progress, a technique has been proposed in which a quencher (acid diffusion controlling agent) is blended in a resist composition, and an acid diffused to a non-exposed part is captured by a salt exchange reaction to improve lithographic performance with ArF exposure (JP-B-5525968). In addition, as a next-generation technology, lithography using a shorter-wavelength radioactive ray such as an electron beam, an X-ray, and extreme ultraviolet (EUV) is also being studied.
According to an aspect of the present disclosure, a radiation-sensitive resin composition includes: an onium salt compound represented by formula (1), a resin comprising a structural unit having an acid-dissociable group, and a solvent.
In the formula (1), R1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms; R2 and R3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R2 and R3 taken together represent a cyclic structure having 3 to 20 ring atoms together with the carbon atom to which R2 and R3 are bonded; R4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms and L1 is a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms, or R4 and L1 taken together represent a group including a heterocyclic structure having 3 to 20 ring atoms together with the nitrogen atom to which R4 and L1 are bonded; L2 is a single bond or a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms; Rf1 and Rf2 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, when there are a plurality of Rf1s and a plurality of Rf2s, the plurality of Rf1s are the same or different from each other, and the plurality of Rf2s are the same or different from each other; n is an integer of 1 to 4; and Z+ is a monovalent radiation-sensitive onium cation.
According to another aspect of the present disclosure, a method for forming a pattern, includes: directly or indirectly applying the above-described radiation-sensitive resin composition to a substrate to form a resist film; exposing the resist film; and developing the exposed resist film with a developer.
According to a further aspect of the present disclosure, an onium salt compound is represented by formula (1).
In the formula (1), R1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms; R2 and R3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R2 and R3 taken together represent a cyclic structure having 3 to 20 ring atoms together with the carbon atoms to which R2 and R3 are bonded; R4 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms and L1 is a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms, or R4 and L1 taken together represent a group including a heterocyclic structure having 3 to 20 ring atoms together with the nitrogen atoms to which R4 and L1 are bonded; L2 is a single bond or a substituted or unsubstituted divalent linking group having 1 to 40 carbon atoms; Rf1 and Rf2 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms; when there are a plurality of Rf1s and a plurality of Rf2s, the plurality of Rf1s are the same or different from each other, and the plurality of Rf1s are the same or different from each other; n is an integer of 1 to 4; and Z+ is a monovalent radiation-sensitive onium cation.
As used herein, the words “a” and “an” and the like carry the meaning of “one or more.” When an amount, concentration, or other value or parameter is given as a range, and/or its description includes a list of upper and lower values, this is to be understood as specifically disclosing all integers and fractions within the given range, and all ranges formed from any pair of any upper and lower values, regardless of whether subranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, as well as all integers and fractions within the range. As an example, a stated range of 1-10 fully describes and includes the independent subrange 3.4-7.2 as does the following list of values: 1, 4, 6, 10.
The present disclosure relates, in an embodiment, to a radiation-sensitive resin composition comprising: an onium salt compound represented by the formula (1) below (hereinafter, also referred to as “onium salt compound (1)”),
The radiation-sensitive resin composition can exhibit superior sensitivity, LWR performance, and CDU performance during resist pattern formation. Although not bound by any theory, the reason for this is presumed as follows. In the radiation-sensitive resin composition, it is presumed that the onium salt compound (1) functions as a quencher (an acid diffusion controlling agent). In an exposed part, it is expected that an acid generated from the onium salt compound (1), another radiation-sensitive acid generator, or the like through exposure deprotects a tertiary alkoxycarbonyl group protecting a nitrogen atom in the molecule of the onium salt compound (1), forms an intramolecular salt in which a sulfonate anion and an ammonium cation coexist together, and results in a dissolved state. The onium salt compound (1) turned into an intramolecular salt form no longer has a quencher function, so that the generated acid is not captured in the exposed part, and therefore the sensitivity of the radiation-sensitive resin composition is increased. On the other hand, in an unexposed part, moderate basicity is maintained by a protected nitrogen atom and a function of capturing an acid can be exhibited. It is presumed that the increased sensitivity due to the loss of the quencher function in the exposed part and the quencher function in the unexposed part are combined to increase the contrast between the exposed part and the unexposed part in such a manner, so that the various resist performances described above are exhibited. In addition, since the solubility in a developer is increased in the exposed part, generation of residues is also controlled, and it is presumed that this also contributes to the improvement of the contrast.
The present disclosure relates to, in another embodiment, a method for forming a pattern, the method comprising:
The method for forming a pattern uses the above-described radiation-sensitive resin composition excellent in sensitivity, LWR performance (line width uniformity performance, which indicates variation in line width of a resist pattern), and CDU performance (critical dimension uniformity performance, which is an index of uniformity of sensitivity, line width, and hole diameter), and therefore a high-quality resist pattern can efficiently be formed.
In still another embodiment, the present disclosure relates to an onium salt compound represented by the following formula (1) (that is, an onium salt compound (1)),
Since in a resist film, the onium salt compound (1) loses a quencher function in an exposed part and can exhibit moderate basicity in an unexposed part, when the onium salt compound is blended in a radiation-sensitive resin composition, it can impart superior sensitivity, LWR performance, and CDU performance at the time of resist pattern formation to the composition.
Hereinbelow, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.
The radiation-sensitive resin composition (hereinafter, also simply referred to as “composition”) according to the present embodiment contains a predetermined onium salt compound (1), a resin, and a solvent. The radiation-sensitive resin composition further contains a radiation-sensitive acid generator, as necessary. The composition may contain other optional components as long as the effects of the present invention are not impaired.
(Onium Salt Compound (1))
The onium salt compound (1) can function as a quencher (also referred to as a “photodegradable base” or “acid diffusion controlling agent”) that captures an acid before exposure or in an unexposed part. The onium salt compound (1) is represented by the above formula (1).
In the formula (1), the monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R1, R2, R3, and R4 are not particularly limited, and examples thereof include monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.
Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.
Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group. Preferred examples of the monocyclic saturated hydrocarbon groups include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The polycyclic cycloalkyl group is preferably a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, or a tetracyclododecyl group. Examples of the monocyclic unsaturated hydrocarbon group include monocyclic cycloalkenyl groups such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the polycyclic unsaturated hydrocarbon group include polycyclic cycloalkenyl groups such as a norbornenyl group, a tricyclodecenyl group, and a tetracyclododecenyl group. It is to be noted that the bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that constitute an alicyclic ring and are not adjacent to each other are bonded by a bonding chain containing one or more carbon atoms.
Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.
Examples of the cyclic structure having 3 to 20 carbon atoms which R2 and R3 are combined with each other to form together with the carbon atoms to which R2 and R3 are bonded include a structure resulting from further removing one hydrogen atom from the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.
In particular, it is preferable that R1, R2, and R3 are each independently a chain hydrocarbon group having 1 to 5 carbon atoms from the viewpoint of the structural stability of the tertiary alkoxycarbonyl group.
Examples of the substituted or unsubstituted divalent linking groups having 1 to 40 carbon atoms represented by L1 and L2 in the above formula (1) include a divalent linear or branched hydrocarbon group having 1 to 40 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, one type of group selected from among —CO—, —O—, —NH—, —S— and a cyclic acetal structure, and a group formed by combining two or more of these groups.
Examples of the divalent linear or branched hydrocarbon group having 1 to 40 carbon atoms include a methanediyl group, an ethanediyl group, a propanediyl group, a butanediyl group, a hexanediyl group, and an octanediyl group. In particular, an alkanediyl group having 1 to 8 carbon atoms is preferable.
Examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group, and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. In particular, cycloalkanediyl groups having 5 to 12 carbon atoms are preferable.
Examples of the substituent to substitute some or all of the hydrogen atoms of L1 and L2 include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.
Examples of the group containing a heterocyclic structure having the number of ring members 3 to 20 which R4 and L1 are combined with each other to form together with the nitrogen atoms to which R4 and L1 are bonded (hereinafter, the group is also referred to as a “heterocyclic structure-containing linking group”) include a group containing an aromatic heterocyclic structure and a group containing an aliphatic heterocyclic structure. A 5-membered aromatic structure having aromaticity by introducing a hetero atom is also included in the heterocyclic structure. Examples of the hetero atom include an oxygen atom, a nitrogen atom, and a sulfur atom.
Examples of the aromatic heterocyclic structure include:
Examples of the aliphatic heterocyclic structure include:
As the heterocyclic structure-containing linking group, not only a heterocyclic structure containing a nitrogen atom but also a combination of a heterocyclic structure containing a nitrogen atom and at least one of the divalent linking groups disclosed as the heterocyclic structure containing a hetero atom other than a nitrogen atom and L1 can be suitably employed. As the heterocyclic structure containing a nitrogen atom, a pyrrolidine structure or a piperidine structure is preferable.
From the viewpoint of ease of intramolecular salt formation, L2 is preferably a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 10 carbon atoms.
As the monovalent hydrocarbon groups having 1 to 10 carbon atoms represented by Rf1 and Rf2 in the formula (1), those corresponding to 1 to 10 carbon atoms among the monovalent hydrocarbon groups having 1 to 20 carbon atoms disclosed as R1 structures can be suitably employed.
Examples of the monovalent fluorinated hydrocarbon groups having 1 to 10 carbon atoms represented by Rf1 and Rf2 in the formula (1) include a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms.
Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms include:
Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms include:
As the fluorinated hydrocarbon group, a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms is preferable, a monovalent fluorinated alkyl group having 1 to 10 carbon atoms is more preferable, a perfluoroalkyl group having 1 to 6 carbon atoms is still more preferable, and a linear perfluoroalkyl group having 1 to 6 carbon atoms is particularly preferable.
n is preferably an integer of 1 to 3, and more preferably 1 or 2.
The anion moiety of the onium salt compound (1) represented by the formula (1) is not particularly limited, and examples thereof include structures represented by the following formulas (1a) to (1z).
In the above formulas, Z+ has the same meanings as that in the formula (1).
in the formula (1), an example of the monovalent radiation-sensitive onium cation is a radioactive ray-degradable onium cation containing an element such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, or Bi. Examples of such a radioactive ray-degradable onium cation include a sulfonium cation, a tetrahydrothiophenium cation, an iodonium cation, a phosphonium cation, a diazonium cation, and a pyridinium cation. Among them, a sulfonium cation or an iodonium cation is preferred. The sulfonium cation or the iodonium cation is preferably represented by any of the following formulas (X-1) to (X-6).
In the above formula (X-1), Ra1, Ra2 and Ra3 are each independently a substituted or unsubstituted, straight or branched chain alkyl group, alkoxy group or alkoxycarbonyloxy group having a carbon number of 1 to 12; a substituted or unsubstituted, monocyclic or polycyclic cycloalkyl group having a carbon number of 3 to 12; a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 to 12; a hydroxy group, a halogen atom, —OSO2—RP, —SO2—RQ or —S—RT; or a ring structure obtained by combining two or more of these groups. The ring structure may contain heteroatoms such as O and S between the carbon-carbon bonds forming the skeleton. RP, RQ and RT are each independently a substituted or unsubstituted, straight or branched chain alkyl group having a carbon number of 1 to 12; a substituted or unsubstituted alicyclic hydrocarbon group having a carbon number of 5 to 25; and a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 to 12. k1, k2 and k3 are each independently an integer of 0 to 5. When there are a plurality of Ra1 to Ra3 and a plurality of RP, RQ and RT, a plurality of Ra1 to Ra3 and a plurality of RP, RQ and RT may be each identical or different.
In the above formula (X-2), Rb1 is a substituted or unsubstituted, straight chain or branched alkyl group or alkoxy group having a carbon number of 1 to 20; a substituted or unsubstituted acyl group having a carbon number of 2 to 8; or a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 to 8; or a hydroxy group. nk is 0 or 1. When nk is 0, k4 is an integer of 0 to 4. When nk is 1, k4 is an integer of 0 to 7. When there are a plurality of Rb1, a plurality of Rb1 may be each identical or different. A plurality of Rb1 may represent a ring structure obtained by combining them. Rb2 is a substituted or unsubstituted, straight chain or branched alkyl group having a carbon number of 1 to 7; or a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 or 7. LC is a single bond or divalent linking group. k5 is an integer of 0 to 4. When there are a plurality of Rb2, a plurality of Rb2 may be each identical or different. A plurality of Rb2 may represent a ring structure obtained by combining them. q is an integer of 0 to 3. In the formula, the ring structure containing S+ may contain a heteroatom such as O or S between the carbon-carbon bonds forming the skeleton.
In the above formula (X-3), Rc1, Rc2 and Rc3 are each independently a substituted or unsubstituted, straight or branched chain alkyl group having a carbon number of 1 to 12.
In the above formula (X-4), Rg1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. nk is 0 or 1. When nk2 is 0, k10 is an integer of 0 to 4, and when nk2 is 1, k10 is an integer of 0 to 7. When there are two or more Rg1s, the two or more Rg1s are the same or different from each other, and may represent a cyclic structure formed by combining them together. Rg2 and Rg3 are each independently a substituted or unsubstituted linear or branched alkyl, alkoxy, or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxyl group, a halogen atom, or a ring structure formed by combining two or more of these groups together. K11 and k12 are each independently an integer of 0 to 4. When there are two or more Rg2s and two or more Rg3s, the two or more Rg2s may be the same or different from each other, and the two or more Rg3s may be the same or different from each other.
In the above formula (X-5), Rd1 and Rd2 are each independently a substituted or unsubstituted, straight or branched chain alkyl group, alkoxy group or alkoxycarbonyl group having a carbon number of 1 to 12; a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 to 12; a halogen atom; a halogenated alkyl group having a carbon number of 1 to 4; a nitro group; or a ring structure obtained by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. When there are a plurality of Rd1 and a plurality of Rd2, a plurality of Rd1 and a plurality of Rd2 may be each identical or different.
In the above formula (X-6), Re1 and Re2 are each independently a halogen atom; a substituted or unsubstituted straight or branched chain alkyl group having a carbon number of 1 to 12; or a substituted or unsubstituted aromatic hydrocarbon group having a carbon number of 6 to 12. k8 and k9 are each independently an integer of 0 to 4.
The onium salt compound (1) is formed of an arbitrary combination of an anion moiety defined by the formula (1) and the aforementioned monovalent radiation-sensitive onium cation. Examples of the onium salt compound (1) are not particularly limited, but include structures represented by the following formulas (1-1) to (1-26).
Among them, the onium salt compounds (1) represented by the formulas (1-1) to (1-24) are preferable.
The content of the onium salt compound (1) in the radiation-sensitive resin composition according to the present embodiment (in the case of using a plurality of types of onium salt compounds in combination, the total content thereof) is more preferably 0.05 parts by mass or more, still more preferably 0.1 parts by mass or more, and particularly preferably 0.5 parts by mass or more based on 100 parts by mass of the resin described later. The content is more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. The content of the onium salt compound (1) is appropriately chosen according to the type of the resin to be used, the exposure conditions, the required sensitivity, and the type and content of the radiation-sensitive acid generator described later. As a result, superior sensitivity, LWR performance, and CDU performance can be exhibited at the time of resist pattern formation.
(Method for Synthesizing Onium Salt Compound (1))
As the onium salt compound (1), a case where R4 and L1 form a piperidine ring structure will be described as an example. Typically, as shown in the following scheme, a target onium salt compound (1) can be synthesized by reacting a halogenated alcohol with a protected piperidine carboxylic acid to form an ester, reacting a dithionite salt with an oxidizing agent to form a sulfonate salt, and finally reacting the sulfonate salt with an onium cation halide corresponding to an onium cation moiety to advance salt exchange,
in the formulas, R1, R2, R3, L2, Rf1, Rf2, Z+ and n have the same meaning as in the above formula (1); Xh1 and Xh2 are halogen atoms.
Similarly, onium salt compounds (1) having other structures can also be synthesized by appropriately selecting a halogenated alcohol to serve as a base of an anion moiety, a carboxylic acid in which a nitrogen atom is protected, and a precursor corresponding to an onium cation moiety.
(Another Acid Diffusion Controlling Agent)
As long as the effect of the present invention is not impaired, the radiation-sensitive resin composition may contain another acid diffusion controlling agent. Examples of the other acid diffusion controlling agent include an onium salt compound that generates a relatively weak acid as compared with the radiation-sensitive acid generator described later other than the onium salt compound (1). Examples thereof include a compound represented by the following formula.
Examples of the other acid diffusion controlling agent include nitrogen-containing compounds other than the onium salt compound (1), and include amine compounds, diamine compounds, polyamine compounds, amide group-containing compounds, urea compounds, and nitrogen-containing heterocyclic compounds.
These nitrogen-containing compounds may be compounds having a tertiary alkoxycarbonyl group that protects a nitrogen atom. These acid diffusion controlling agents may be used singly, or two or more thereof may be used in combination.
The resin is an aggregate of polymers having a structural unit (hereinafter, also referred to as “structural unit (I)”) containing an acid-dissociable group (hereinafter, this resin is also referred to as “base resin”). The “acid-dissociable group” refers to a group that substitutes for a hydrogen atom of a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and is dissociated by the action of an acid. The radiation-sensitive resin composition is excellent in pattern-forming performance because the resin has the structural unit (I).
In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure described later, and may have another structural unit other than the structural units (I) and (II). Each of the structural units will be described below.
The structural unit (I) contains an acid-dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid-dissociable group. Examples of such a structural unit (I) include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure obtained by substituting the hydrogen atom of a phenolic hydroxyl group with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern-forming performance of the radiation-sensitive resin composition, a structural unit represented by the following formula (3) (hereinafter also referred to as a “structural unit (I-1)”) is preferred.
(In the above formula (3), R7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, R8 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R9 and R10 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R9 and R10 represent a divalent alicyclic group having 3 to 20 carbon atoms which R9 and R10 are combined to form together with a carbon atom to which R9 and R10 are bonded.
From the viewpoint of copolymerizability of a monomer that will give the structural unit (I-1), R7 is preferably a hydrogen atom or a methyl group, more preferably a methyl group.
Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R8 include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
Examples of the chain hydrocarbon groups having 1 to 10 carbon atoms represented by R8 to R10 include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms and linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.
Examples of the alicyclic hydrocarbon groups having 3 to 20 carbon atoms represented by R8 to R10 include monocyclic or polycyclic saturated hydrocarbon groups and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred examples of the monocyclic saturated hydrocarbon groups include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Preferred examples of the polycyclic saturated hydrocarbon groups include bridged alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. It is to be noted that the bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that constitute an alicyclic ring and not adjacent to each other are bonded by a bonding chain containing at least one carbon atom.
Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R8 include: aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.
R8 is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.
The divalent alicyclic group having 3 to 20 carbon atoms which R9 and R10 are combined to form together with a carbon atom to which R9 and R10 are bonded is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above-described carbon number. The divalent alicyclic group having 3 to 20 carbon atoms may either be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. The polycyclic hydrocarbon group may either be a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group and may either be a saturated hydrocarbon group or an unsaturated hydrocarbon group. It is to be noted that the condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two or more alicyclic rings share their sides (bond between two adjacent carbon atoms).
When the monocyclic alicyclic hydrocarbon group is a saturated hydrocarbon group, preferred examples thereof include a cyclopentanediyl group, a cyclohexanediyl group, a cycloheptanediyl group, and a cyclooctanediyl group. When the monocyclic alicyclic hydrocarbon group is an unsaturated hydrocarbon group, preferred examples thereof include a cyclopentenediyl group, a cyclohexenediyl group, a cycloheptenediyl group, a cyclooctenediyl group, and a cyclodecenediyl group. The polycyclic alicyclic hydrocarbon group is preferably a bridged alicyclic saturated hydrocarbon group, and preferred examples thereof include a bicyclo[2.2.1]heptane-2,2-diyl group (norbornane-2,2-diyl group), a bicyclo[2.2.2]octane-2,2-diyl group, and a tricyclo[3.3.1.13,7]decane-2,2-diyl group (adamantane-2,2-diyl group).
Among them, R8 is preferably an alkyl group having 1 to 4 carbon atoms, and the alicyclic structure which R9 and R10 are combined to form together with a carbon atom to which R9 and R10 are bonded is preferably a polycyclic or monocyclic cycloalkane structure.
Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as “structural units (I-1-1) to (I-1-6)”).
In the above formulas (3-1) to (3-6), R7 to R10 have the same meaning as in the above formula (3), i and j are each independently an integer of 1 to 4, and k and 1 are each 0 or 1.
In the above formulas (3-1) to (3-6), i and j are preferably 1, and R8 is preferably a methyl group, an ethyl group, or an isopropyl group. R9 and R10 are each preferably a methyl group, or an ethyl group
The base resin may contain one type or a combination of two or more types of the structural units (I).
The content of the structural unit (I) (a total content when a plurality of types are contained) is preferably 10 mol % or more, more preferably 20 mol % or more, still more preferably 30 mol % or more, and particularly preferably 35 mol % or more based on all structural units constituting the base resin. The content is preferably 80 mol % or less, more preferably 75 mol % or less, still more preferably 70 mol % or less, and particularly preferably 65 mol % or less. When the content of the structural unit (I) is set to fall within the above range, the pattern-forming performance of the radiation-sensitive resin composition can further be improved.
The structural unit (II) is a structural unit including at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure and a sultone structure. The solubility of the base resin into a developer can be adjusted by further introducing the structural unit (II). As a result, the radiation-sensitive resin composition can provide improved lithography properties such as the resolution. The adhesion between a resist pattern formed from the base resin and a substrate can also be improved.
Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10)
In the above formulae, RL1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; RL2 to RL5 are each independently a hydrogen atom, an alkyl group having a carbon number of 1 to 4, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group; RL4 and RL5 may be a divalent alicyclic group having a carbon number of 3 to 8, which is obtained by combining RL4 and RL5 with the carbon atom to which they are bound. L2 is a single bond, or a divalent linking group; X is an oxygen atom or a methylene group; k is an integer of 0 to 3; and m is an integer of 1 to 3.
Example of the divalent alicyclic group having a carbon number of 3 to 8, which is composed of a combination of RL4 and RL5 with the carbon atom to which they are bound, includes the divalent alicyclic group having a carbon number of 3 to 8 in the divalent alicyclic group having a carbon number of 3 to 20, which is composed of a combination of the chain hydrocarbon group or the alicyclic hydrocarbon group represented by R9 and R10 in the above formula (3) with the carbon atom to which they are bound. One or more hydrogen atoms on the alicyclic group may be substituted with a hydroxy group.
Examples of the divalent linking group represented by L2 as described above include a divalent straight or branched chain hydrocarbon group having a carbon number of 1 to 10; a divalent alicyclic hydrocarbon group having a carbon number of 4 to 12; and a group composed of one or more of the hydrocarbon group thereof and at least one group of —CO—, —O—, —NH— and —S—.
Among them, the structural unit (II) is preferably a group having a lactone structure, more preferably a group having a norbornane lactone structure, and further preferably a group derived from a norbornane lactone-yl (meth)acrylate.
The lower limit of the content by percent of the structural unit (II) is preferably 20 mol %, more preferably 25 mol %, and further preferably 30 mol % based on the total structural units as the component of the base resin. The upper limit of the content by percent is preferably 80 mol %, more preferably 75 mol %, and further preferably 70 mol %. By adjusting the content by percent of the structural unit D within the ranges, the radiation-sensitive resin composition can provide improved lithography properties such as the resolution. The adhesion between the formed resist pattern and the substrate can also be improved.
The base resin optionally has another structural unit in addition to the structural units (I) and (II). Another structural unit includes a structural unit (III) containing a polar group (excluding those corresponding to the structural unit (II)). When the base resin further has a structural unit (III), solubility in the developer can be adjusted. As a result, lithographic performance such as resolution of the radiation-sensitive resin composition can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among them, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.
Examples of the structural unit (III) include structural units represented by the following formulas.
In the above formulas, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
When the resin includes the structural unit (III) having a polar group, the lower limit of the content of the structural unit (III) with respect to the total amount of the structural units constituting the resin is preferably 5 mol %, more preferably 8 mol %, even more preferably 10 mol %. The upper limit of the content is preferably 40 mol %, more preferably 35 mol %, even more preferably 30 mol %. When the content of the structural unit having a polar group is set to fall within the above range, the radiation-sensitive resin composition can provide further improved lithography properties such as the resolution.
[Structural unit (IV)]
The base resin optionally has, as another structural unit, a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both are also collectively referred to as “structural unit (IV)”), in addition to the structural unit (III) having a polar group. The structural unit (IV) contributes to an improvement in etching resistance and an improvement in a difference in solubility of a developer (dissolution contrast) between an exposed part and a non-exposed part. In particular, the structural unit (IV) can be suitably applied to pattern formation using exposure with a radioactive ray having a wavelength of 50 nm or less, such as an electron beam or EUV. In this case, the resin preferably has the structural units (I), (III) together with the structural unit (IV).
In this case, it is preferable to obtain the structural unit (IV) by performing polymerization in a state in which the phenolic hydroxyl group is protected by a protective group such as an alkali-dissociable group during polymerization, and then performing deprotection by hydrolysis. The structural unit that provides the structural unit (IV) by hydrolysis is preferably represented by the following formulas (4-1) and (4-2).
In the above formulas (4-1) and (4-2), R11 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and R12 is a monovalent hydrocarbon group having 1 to 20 carbon atoms or an alkoxy group. Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms for R12 include monovalent hydrocarbon groups having 1 to 20 carbon atoms for R8 in the structural unit (I). Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.
As R12, an alkyl group and an alkoxy group are preferable, and among them, a methyl group and a tert-butoxy group are more preferable.
In the case of a resin for exposure with a radioactive ray having a wavelength of 50 nm or less, the lower limit of the content of the structural unit (IV) is preferably 10 mol %, more preferably 20 mol %, with respect to the total amount of structural units constituting the resin. The upper limit of the content is preferably 70 mol %, more preferably 60 mol %.
(Synthesis Method of Base Resin)
For example, the base resin can be synthesized by performing a polymerization reaction of each monomer for providing each structural unit with a radical polymerization initiator or the like in a suitable solvent.
Examples of the radical polymerization initiator include an azo-based radical initiator, including azobisisobutyronitrile (AIBN), 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis(2-cyclopropylpropanenitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2′-azobisisobutyrate; and peroxide-based radical initiator, including benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among them, AIBN or dimethyl 2,2′-azobisisobutyrate is preferred, and AIBN is more preferred. The radical initiator may be used alone, or two or more radical initiators may be used in combination.
Examples of the solvent used for the polymerization reaction include
The reaction temperature of the polymerization reaction is typically from 40° C. to 150° C., and preferably from 50° C. to 120° C. The reaction time is typically from 1 hour to 48 hours, and preferably from 1 hour to 24 hours.
The molecular weight of the base resin is not particularly limited, but the polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, particularly preferably 4,000 or more. Mw is preferably 50,000 or less, more preferably 30,000 or less, still more preferably 15,000 or less, particularly preferably 12,000 or less. When the Mw of the base resin is less than the lower limit, the heat resistance of the resulting resist film may be deteriorated. When the Mw of the base resin exceeds the above upper limit, the developability of the resist film may be deteriorated.
For the base resin as a base resin, the ratio of Mw to the number average molecular weight (Mn) as determined by GPC relative to standard polystyrene (Mw/Mn) is typically not less than 1 and not more than 5, preferably not less than 1 and not more than 3, and more preferably not less than 1 and not more than 2.
The Mw and Mn of the resin in the specification are amounts measured by using Gel Permeation Chromatography (GPC) with the condition as described below.
The content of the base resin is preferably not less than 70% by mass, more preferably not less than 80% by mass, and further preferably not less than 85% by mass based on the total solid content of the radiation-sensitive resin composition.
<Another Resin>
The radiation-sensitive resin composition according to the present embodiment may contain, as another resin, a resin having higher content by mass of fluorine atoms than the above-described base resin (hereinafter, also referred to as a “high fluorine-content resin”). When the radiation-sensitive resin composition contains the high fluorine-content resin, the high fluorine-content resin can be localized in the surface layer of a resist film compared to the base resin, which as a result makes it possible to enhance the water repellency of the surface of the resist film during immersion exposure.
The high fluorine-content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter, also referred to as “structural unit (V)”), and may have the structural unit (I) or the structural unit (II) in the base resin as necessary.
In the above formula (5), R13 is a hydrogen atom, a methyl group, or a trifluoromethyl group; GL is a single bond, an oxygen atom, a sulfur atom, —COO—, —SO2ONH—, —CONH—, or —OCONH—; R14 is a monovalent fluorinated chain hydrocarbon group having a carbon number of 1 to 20, or a monovalent fluorinated alicyclic hydrocarbon group having a carbon number of 3 to 20.
As R13 as described above, in terms of the copolymerizability of monomers resulting in the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.
As GL as described above, in terms of the copolymerizability of monomers resulting in the structural unit (V), a single bond or —COO— is preferred, and —COO— is more preferred.
Example of the monovalent fluorinated chain hydrocarbon group having a carbon number of 1 to 20 represented by R14 as described above includes a group in which a part of or all of hydrogen atoms in the straight or branched chain alkyl group having a carbon number of 1 to 20 is/are substituted with a fluorine atom.
Example of the monovalent fluorinated alicyclic hydrocarbon group having a carbon number of 3 to 20 represented by R14 as described above includes a group in which a part of or all of hydrogen atoms in the monocyclic or polycyclic hydrocarbon group having a carbon number of 3 to 20 is/are substituted with a fluorine atom.
The R14 as described above is preferably a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and further preferably 2,2,2-trifluoroethyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group and 5,5,5-trifluoro-1,1-diethylpentyl group.
When the high fluorine-content resin has the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 30 mol %, more preferably 40 mol %, even more preferably 45 mol %, particularly preferably 50 mol % with respect to the total amount of all the structural units constituting the high fluorine-content resin. The upper limit of the content is preferably 90 mol %, more preferably 85 mol %, even more preferably 80 mol %. When the content of the structural unit (V) is set to fall within the above range, the content by mass of fluorine atoms of the high fluorine-content resin can more appropriately be adjusted to further promote the localization of the high fluorine-content resin in the surface layer of a resist film, as a result, the water repellency of the resist film during immersion exposure can be further improved.
The high fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter, also referred to as a “structural unit (VI)”) in addition to or in place of the structural unit (V). When the high fluorine-content resin has the structural unit (VI), solubility in an alkaline developing solution is improved, and therefore generation of development defects can be prevented.
The structural unit (VI) is classified into two groups: a unit having an alkali soluble group (x); and a unit having a group (y) in which the solubility into the alkaline developing solution is increased by the dissociation by alkali (hereinafter, simply referred as an “alkali-dissociable group”). In both cases of (x) and (y), RC in the above formula (f-2) is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; RD is a single bond, a hydrocarbon group having a carbon number of 1 to 20 with the valency of (s+1), a structure in which an oxygen atom, a sulfur atom, —NRdd—, a carbonyl group, —COO— or —CONH— is connected to the terminal on RE side of the hydrocarbon group, or a structure in which a part of hydrogen atoms in the hydrocarbon group is substituted with an organic group having a hetero atom; Rdd is a hydrogen atom, or a monovalent hydrocarbon group having a carbon number of 1 to 10; and s is an integer of 1 to 3.
When the structural unit (VI) has the alkali soluble group (x), RE is a hydrogen atom; A1 is an oxygen atom, —COO—* or —SO2O—*; * refers to a bond to RE; W1 is a single bond, a hydrocarbon group having a carbon number of 1 to 20, or a divalent fluorinated hydrocarbon group. When A1 is an oxygen atom, W1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom connecting to A1. RE is a single bond, or a divalent organic group having a carbon number of 1 to 20. When s is 2 or 3, a plurality of RE, W1, A1 and RE may be each identical or different. The affinity of the high fluorine-content resin into the alkaline developing solution can be improved by including the structural unit (VI) having the alkali soluble group (x), and thereby prevent from generating the development defect. As the structural unit (VI) having the alkali soluble group (x), particularly preferred is a structural unit in which A1 is an oxygen atom and W1 is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.
When the structural unit (VI) has the alkali-dissociable group (y), RF is a monovalent organic group having carbon number of 1 to 30; A1 is an oxygen atom, —NRaa—, —COO—*, or —SO2O—*; Raa is a hydrogen atom, or a monovalent hydrocarbon group having a carbon number of 1 to 10; * refers to a bond to RF; W1 is a single bond, or a divalent fluorinated hydrocarbon group having a carbon number of 1 to 20; RE is a single bond, or a divalent organic group having a carbon number of 1 to 20. When A1 is —COO—* or —SO2O—*, W1 or RF has a fluorine atom on the carbon atom connecting to A1 or on the carbon atom adjacent to the carbon atom. When A1 is an oxygen atom, W1 and RE are a single bond; RD is a structure in which a carbonyl group is connected at the terminal on RE side of the hydrocarbon group having a carbon number of 1 to 20; and RF is an organic group having a fluorine atom. When s is 2 or 3, a plurality of RE, W1, A1 and RF may be each identical or different. The surface of the resist film is changed from hydrophobic to hydrophilic in the alkaline developing step by including the structural unit (VI) having the alkali-dissociable group (y). As a result, the affinity of the high fluorine-content resin into the alkaline developing solution can be significantly improved, and thereby prevent from generating the development defect more efficiently. As the structural unit (VI) having the alkali-dissociable group (y), particularly preferred is a structural unit in which A1 is —COO—*, and RF or W1, or both is/are a fluorine atom.
In terms of the copolymerizability of monomers resulting in the structural unit (VI), RC is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.
When RE is a divalent organic group, RE is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and further preferably a group having a norbornane lactone structure.
When the high fluorine-content resin contains the structural unit (VI), the content of the structural unit (VI) is preferably 50 mol % or more, more preferably 55 mol % or more, and still more preferably 60 mol % or more based on all structural units constituting the high fluorine-content resin. The content is preferably 95 mol % or less, more preferably 90 mol % or less, and still more preferably 85 mol % or less. When the content of the structural unit (VI) is set to fall within the above range, water repellency of a resist film during immersion exposure can further be improved.
A high fluorine-content resin may contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the structural units listed above,
in the formula (6), R1α represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and R2α represents a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.
In the formula (6), as the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R2α, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R8 in the formula (1) can be suitably employed.
When the high fluorine-content resin contains the structural unit having an alicyclic structure, the content of the structural unit having an alicyclic structure is preferably 10 mol % or more, more preferably 20 mol % or more, and still more preferably 30 mol % or more based on all structural units constituting the high fluorine-content resin. The content is preferably 60 mol % or less, more preferably 50 mol % or less, and still more preferably 40 mol % or less.
The Mw of the high fluorine-content resin is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, and particularly preferably 5,000 or more. The Mw is preferably 50,000 or less, more preferably 30,000 or less, still more preferably 15,000 or less, and particularly preferably 12,000 or less.
The lower limit of the Mw/Mn of the high fluorine-content resin is typically 1, and more preferably 1.1. The upper limit of the Mw/Mn is typically 5, preferably 3, more preferably 2, and further preferably 1.9.
The content of the high fluorine-content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more based on 100 parts by mass of the base resin. The content of the high fluorine-content resin is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.
When the content of the high fluorine-content resin is set to fall within the above range, the high fluorine-content resin can more effectively be localized in the surface layer of a resist film, which as a result makes it possible to further enhance the water repellency of the surface of the resist film during liquid immersion lithography or modify the surface of the resist film. The radiation-sensitive resin composition may contain one high fluorine-content resin or two or more high fluorine-content resins.
(Method for Synthesizing High Fluorine-Content Resin)
The high fluorine-content resin can be synthesized by a method similar to the above-described method for synthesizing a base resin.
The radiation-sensitive resin composition of the present embodiment preferably further contains a radiation-sensitive acid generator that generates, by irradiation with radiation (exposure), an acid having a pKa smaller than that of the acid generated from the onium salt compound (1) that functions as the acid diffusion controlling agent, that is, a relatively strong acid. When the resin contains the structural unit (I) having an acid-dissociable group, the acid generated from the radiation-sensitive acid generator by exposure can dissociate the acid-dissociable group of the structural unit (I) to generate a carboxy group or the like. This function is different from the function of the onium salt compound (1) that suppresses the diffusion of the acid generated from the radiation-sensitive acid generator in the non-exposed part without substantially dissociating the acid-dissociable group or the like of the structural unit (I) or the like of the resin under the pattern formation condition using the radiation-sensitive resin composition. Each function of the onium salt compound (1) and the radiation-sensitive acid generator depends on energy required for the dissociation of the acid-dissociable group of the structural unit (I) or the like of the resin, and heat energy conditions applied when a pattern is formed using the radiation-sensitive resin composition, and the like. The containing mode of the radiation-sensitive acid generator in the radiation-sensitive resin composition may be a mode in which the radiation-sensitive acid generator is present alone as a compound (released from a polymer), a mode in which the radiation-sensitive acid generator is incorporated as a part of a polymer, or both of these forms, but a mode in which the radiation-sensitive acid generator is present alone as a compound is preferable.
When the radiation-sensitive resin composition contains the radiation-sensitive acid generator, the polarity of the resin in the exposed part increases, whereby the resin in the exposed part is soluble in the developer in the case of alkaline aqueous solution development, and is poorly soluble in the developer in the case of organic solvent development.
Examples of the radiation-sensitive acid generator include an onium salt compound (excluding the onium salt compound (1)), a sulfonimide compound, a halogen-containing compound, and a diazoketone compound. Examples of the onium salt compound include a sulfonium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, and a pyridinium salt. Among them, a sulfonium salt and an iodonium salt are preferable.
Examples of the acid generated during exposure include sulfonic acid. Examples of such an acid include a sulfonium salt having an anion in which the carbon atom adjacent to the sulfo group is substituted with one or more fluorine atoms or fluorinated hydrocarbon groups. Among them, as the radiation-sensitive acid generator, one having a cyclic structure in a cation and an anion is particularly preferable.
These radiation-sensitive acid generators may be used alone or in combination of two or more thereof. The content of the radiation-sensitive acid generator (when a plurality of types of radiation-sensitive acid generators are used, their total content is taken) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 5 parts by mass or more based on 100 parts by mass of the base resin). The content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less based on 100 parts by mass of the base resin. As a result, superior sensitivity, LWR performance, and CDU performance can be exhibited at the time of resist pattern formation.
<Solvent>
The radiation-sensitive resin composition according to the present embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin, the radiation-sensitive acid generator, and an additive or the like contained if necessary.
Examples of the solvent include an alcohol-based solvent, an ether-based solvent, a ketone-based solvent, an amide-based solvent, an ester-based solvent, and a hydrocarbon-based solvent.
Examples of the alcohol-based solvent include:
Examples of the ether-based solvent include:
Examples of the ketone-based solvent include:
Examples of the amide-based solvent include:
Examples of the ester-based solvent include:
Examples of the hydrocarbon-based solvent include:
Among them, the ester-based solvent or the ketone-based solvent is preferred. The partially etherized polyhydric alcohol acetate-based solvent, the cyclic ketone-based solvent, or the lactone-based solvent is more preferred. Propylene glycol monomethyl ether acetate, cyclohexanone, or γ-butyrolactone is still more preferred. The radiation-sensitive resin composition may include one type of the solvent, or two or more types of the solvents in combination.
<Other Optional Components>
The radiation-sensitive resin composition may contain other optional components other than the above-descried components. Examples of other optional components include a cross-linking agent, a localization enhancing agent, a surfactant, an alicyclic backbone-containing compound, and a sensitizer. These other optional components may be used singly or in combination of two or more of them.
<Method for Preparing Radiation-Sensitive Resin Composition>
The radiation-sensitive resin composition can be prepared by, for example, mixing the onium salt compound (1), the resin, the radiation-sensitive acid generator, and optionally the high fluorine-content resin, as well as the solvent added in a predetermined ratio. The radiation-sensitive resin composition is preferably filtered through, for example, a filter having a pore diameter of about 0.05 μm to 0.20 μm after mixing. The solid matter concentration of the radiation-sensitive resin composition is usually 0.1 mass % to 50 mass %, preferably 0.5 mass % to 30 mass %, more preferably 1 mass % to 20 mass %.
A pattern forming method according to an embodiment of the present disclosure includes:
The method for forming a pattern uses the above-described radiation-sensitive resin composition excellent in sensitivity in the exposure step, CDU performance, and LWR performance, and therefore a high-quality resist pattern can be formed. Hereinbelow, each of the steps will be described.
[Resist Film Forming Step]
In this step (the above mentioned step (1)), a resist film is formed with the radiation-sensitive resin composition. Examples of the substrate on which the resist film is formed include one traditionally known in the art, including a silicon wafer, silicon dioxide, and a wafer coated with aluminum. An organic or inorganic antireflection film may be formed on the substrate, as disclosed in JP-B-06-12452 and JP-A-59-93448. Examples of the applicating method include a rotary coating (spin coating), flow casting, and roll coating. After applicating, a prebake (PB) may be carried out in order to evaporate the solvent in the film, if needed. The temperature of PB is typically from 60° C. to 140° C., and preferably from 80° C. to 120° C. The duration of PB is typically from 5 seconds to 600 seconds, and preferably from 10 seconds to 300 seconds. The thickness of the resist film formed is preferably from 10 nm to 1,000 nm, and more preferably from 10 nm to 500 nm.
When the immersion exposure is carried out, irrespective of presence of a water repellent polymer additive such as the high fluorine-content resin in the radiation-sensitive resin composition, the formed resist film may have a protective film for the immersion which is not soluble into the immersion liquid on the film in order to prevent a direct contact between the immersion liquid and the resist film. As the protective film for the immersion, a solvent-removable protective film that is removed with a solvent before the developing step (for example, see JP-A-2006-227632); or a developer-removable protective film that is removed during the development of the developing step (for example, see W02005-069076 and WO2006-035790) may be used. In terms of the throughput, the developer-removable protective film is preferably used.
When the next step, the exposure step, is performed with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit (I) and the structural unit (IV) as the base resin in the composition.
[Exposing Step]
In this step (the above mentioned step (2)), the resist film formed in the resist film forming step as the step (1) is exposed by irradiating with a radioactive ray through a photomask (optionally through an immersion medium such as water). Examples of the radioactive ray used for the exposure include visible ray, ultraviolet ray, far ultraviolet ray, extreme ultraviolet ray (EUV); an electromagnetic wave including X ray and γ ray; an electron beam; and a charged particle radiation such as a ray. Among them, far ultraviolet ray, an electron beam, or EUV is preferred. ArF excimer laser light (wavelength is 193 nm), KrF excimer laser light (wavelength is 248 nm), an electron beam, or EUV is more preferred. An electron beam or EUV having a wavelength of 50 nm or less which is identified as the next generation exposing technology is further preferred.
When the exposure is carried out by immersion exposure, examples of the immersion liquid include water and fluorine-based inert liquid. The immersion liquid is preferably a liquid which is transparent with respect to the exposing wavelength, and has a minimum temperature factor of the refractive index so that the distortion of the light image reflected on the film becomes minimum. However, when the exposing light source is ArF excimer laser light (wavelength is 193 nm), water is preferably used because of the ease of availability and ease of handling in addition to the above considerations. When water is used, a small proportion of an additive that decreases the surface tension of water and increases the surface activity may be added. Preferably, the additive cannot dissolve the resist film on the wafer and can neglect an influence on an optical coating at an under surface of a lens. The water used is preferably distilled water.
After the exposure, post exposure bake (PEB) is preferably carried out to promote the dissociation of the acid-dissociable group in the resin by the acid generated from the radiation-sensitive acid generator with the exposure in the exposed part of the resist film. The difference of solubility into the developer between the exposed part and the non-exposed part is generated by the PEB. The temperature of PEB is typically from 50° C. to 180° C., and preferably from 80° C. to 130° C. The duration of PEB is typically from 5 seconds to 600 seconds, and preferably from 10 seconds to 300 seconds.
[Developing Step]
In this step (the above mentioned step (3)), the resist film exposed in the exposing step as the step (2) is developed. By this step, the predetermined resist pattern can be formed. After the development, the resist pattern is washed with a rinse solution such as water or alcohol, and the dried, in general.
Examples of the developer used for the development include, in the alkaline development, an alkaline aqueous solution obtained by dissolving at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethyl ammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene. Among them, an aqueous TMAH solution is preferred, and 2.38% by mass of aqueous TMAH solution is more preferred.
In the case of the development with organic solvent, examples of the solvent include an organic solvent, including a hydrocarbon-based solvent, an ether-based solvent, an ester-based solvent, a ketone-based solvent, and an alcohol-based solvent; and a solvent containing an organic solvent. Examples of the organic solvent include one, two or more solvents listed as the solvent for the radiation-sensitive resin composition. Among them, an ether-based solvent, an ester-based solvent or a ketone-based solvent is preferred. As the ether-based solvent, a glycol ether-based solvent is preferable, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferable. The ester-based solvent is preferably an acetate ester-based solvent, and more preferably n-butyl acetate or amyl acetate. The ketone-based solvent is preferably a chain ketone, and more preferably 2-heptanone. The content of the organic solvent in the developer is preferably not less than 80% by mass, more preferably not less than 90% by mass, further preferably not less than 95% by mass, and particularly preferably not less than 99% by mass. Examples of the ingredient other than the organic solvent in the developer include water and silicone oil.
As described above, the developer may be either an alkaline developer or an organic solvent developer, but it is preferable that the developer contains an alkaline aqueous solution and the obtained pattern is a positive pattern.
Examples of the developing method include a method of dipping the substrate in a tank filled with the developer for a given time (dip method); a method of developing by putting and leaving the developer on the surface of the substrate with the surface tension for a given time (paddle method); a method of spraying the developer on the surface of the substrate (spray method); and a method of injecting the developer while scanning an injection nozzle for the developer at a constant rate on the substrate rolling at a constant rate (dynamic dispense method).
The onium salt compound according to still another embodiment of the present disclosure is represented by the above formula (1).
As the onium salt compound represented by the formula (1) according to the present embodiment, the onium salt compound (1) contained in the radiation-sensitive resin composition can be suitably used.
Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. Methods for measuring various physical property values are shown below.
The Mw and Mn of the polymer were measured under the conditions described above. The polydispersity (Mw/Mn) was calculated from the measurement results of Mw and Mn.
13C-NMR analysis of the polymer was performed using a nuclear magnetic resonance apparatus (“JNM-Delta 400” manufactured by JEOL Ltd.).
The monomers used in the synthesis of each resin and high fluorine-content resin in Examples and Comparative Examples are shown below. In the following synthesis examples, unless otherwise specified, parts by mass means a value when the total mass of monomers used is 100 parts by mass, and mol % means a value when the total number of moles of monomers used is 100 mol %.
The monomer (M-1), the monomer (M-2), and the monomer (M-13) were dissolved in 2-butanone (200 parts by mass) so as to have a molar ratio of 40/15/45 (mol %), and AIBN (azobisisobutyronitrile) (3 mol % with respect to 100 mol % in total of the used monomers) was added as an initiator to prepare a monomer solution. A reaction vessel was charged with 2-butanone (100 parts by mass) and purged with nitrogen for 30 minutes, and inside of the reaction vessel was adjusted to 80° C. Then, the monomer solution was added dropwise thereto over 3 hours with stirring. The polymerization reaction was performed for 6 hours with the start of dropwise addition as the initiation time of the polymerization reaction. After completion of the polymerization reaction, the polymerization solution was cooled to 30° C. or lower by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was separated by filtration. The separated white powder was washed with methanol twice, then separated by filtration, and dried at 50° C. for 24 hours to obtain a white powdery resin (A-1) (yield: 83%). The resin (A-1) had a Mw of 8,800 and a Mw/Mn of 1.50. As a result of 13C-NMR analysis, the contents of the structural units derived from (M-1), (M-2), and (M-13) were 41.3 mol %, 13.8 mol %, and 44.9 mol %, respectively.
Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1 except that monomers of types and blending ratios shown in the following Table 1 were used. The content (mol %), yield (%), and physical property values (Mw and Mw/Mn) of each structural unit of the obtained resins are shown together in the following Table 1. Incidentally, “-” in the following Table 1 indicates that the corresponding monomer was not used (the same applies to the following tables).
The monomer (M-1) and the monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so as to have a molar ratio of 50/50 (mol %), and AIBN (5 mol %) was added as an initiator to prepare a monomer solution. A reaction vessel was charged with 1-methoxy-2-propanol (100 parts by mass) and purged with nitrogen for 30 minutes, and inside of the reaction vessel was adjusted to 80° C. Then, the monomer solution was added dropwise thereto over 3 hours with stirring. The polymerization reaction was performed for 6 hours with the start of dropwise addition as the initiation time of the polymerization reaction. After completion of the polymerization reaction, the polymerization solution was cooled to 30° C. or lower by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was separated by filtration. The separated white powder was washed twice with hexane, then separated by filtration, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Subsequently, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was performed at 70° C. for 6 hours with stirring. After completion of the reaction, the remaining solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). The solution was added dropwise to water (500 parts by mass) to solidify the resin. The resulting solid was separated by filtration and dried at 50° C. for 13 hours to obtain a white powdery resin (A-12) (yield: 79%). The resin (A-12) had a Mw of 5,200 and a Mw/Mn of 1.60. As a result of 13C-NMR analysis, the contents of the structural units derived from (M-1) and (M-18) were 51.3 mol % and 48.7 mol %, respectively.
Resins (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12 except that monomers of types and blending ratios shown in the following Table 2 were used. The content (mol %), yield (%), and physical property values (Mw and Mw/Mn) of each structural unit of the obtained resins are also shown in the following Table 2.
The monomer (M-1) and the monomer (M-20) were dissolved in 2-butanone (200 parts by mass) so as to have a molar ratio of 20/80 (mol %), and AIBN (4 mol %) was added as an initiator to prepare a monomer solution. A reaction vessel was charged with 2-butanone (100 parts by mass) and purged with nitrogen for 30 minutes, and inside of the reaction vessel was adjusted to 80° C. Then, the monomer solution was added dropwise thereto over 3 hours with stirring. The polymerization reaction was performed for 6 hours with the start of dropwise addition as the initiation time of the polymerization reaction. After completion of the polymerization reaction, the polymerization solution was cooled to 30° C. or lower by water cooling. The operation of replacing the solvent with acetonitrile (400 parts by mass), then adding hexane (100 parts by mass), stirring the mixture, and recovering the acetonitrile layer was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of a high fluorine-content resin (E-1) (yield: 69%). The high fluorine-content resin (E-1) had a Mw of 6,000 and a Mw/Mn of 1.62. As a result of 13C-NMR analysis, the contents of the structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.
High fluorine-content resins (E-2) to (E-5) were synthesized in the same manner as in Synthesis Example 16 except that monomers of the types and blending ratios shown in the following Table 3 were used. The content (mol %), yield (%), and physical property values (Mw and Mw/Mn) of each structural unit of the obtained high fluorine-content resins are shown in the following Table 3.
An onium salt compound (C-1) was synthesized in accordance with the synthesis scheme below.
20.0 mmol of 6-bromo-5,5,6,6-tetrafluorohexan-1-ol, 30.0 mmol of 1-(tert-butoxycarbonyl)-4-piperidinecarboxylic acid, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride were added to a reaction vessel, and the mixture was stirred at room temperature for 4 hours. Thereafter, the reaction product was diluted by adding water, and methylene chloride was then added thereto to perform extraction, thereby separating an organic layer. The resulting organic layer was washed with a saturated aqueous solution of sodium chloride and then with water. After drying over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography, affording a bromo body in a good yield.
A mixed solution of acetonitrile and water (1:1 (mass ratio)) was added to the bromo body to form a 1 M solution, and then 40.0 mmol of sodium dithionite and 60.0 mmol of sodium hydrogen carbonate were added thereto, and the mixture was reacted at 70° C. for 4 hours. After extraction with acetonitrile and distillation of the solvent, a mixed solution of acetonitrile and water (3:1 (mass ratio)) was added to form a 0.5 M solution. 60.0 mmol of hydrogen peroxide water and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50° C. for 12 hours. The mixture was extracted with acetonitrile, and the solvent was distilled off, affording a sodium sulfonate salt compound. 20.0 mmol of triphenylsulfonium bromide was added to the sodium sulfonate salt compound, and a mixed solution of water and dichloromethane (1:3 (mass ratio)) was added to form a 0.5 M solution. The mixture was vigorously stirred at room temperature for 3 hours, then extracted by adding dichloromethane, and an organic layer was separated. After the obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the residue was purified by column chromatography, affording an onium salt compound (C-1) represented by the above formula (C-1) in a good yield.
Onium salt compounds represented by formulas (C-2) to (C-24) below were synthesized in the same manner as in Synthesis Example 21 except that the raw materials and the precursor were appropriately changed.
[Onium Salt Compounds Other than Onium Salt Compounds (C-1) to (C-24)]
cc-1 to cc-12: Onium salt compounds represented by the following formulas (cc-1) to (cc-12) (Hereinafter, the onium salt compounds represented by the formulas (cc-1) to (cc-12) may be described as “onium salt compounds (cc-1) to (cc-12)”, respectively.)
B-1 to B-6: Compounds represented by the following formulas (B-1) to (B-6) (Hereinafter, the compounds represented by the formulas (B-1) to (B-6) may be described as “compound (B-1)” to “compound (B-6)”, respectively.)
100 parts by mass of (A-1) as the resin [A], 12.0 parts by mass of (B-1) as the radiation-sensitive acid generator [B], 5.0 parts by mass of (C-1) as the acid diffusion controlling agent [C], 3.0 parts by mass (solid content) of (E-1) as the high fluorine-content resin [E], and 3,230 parts by mass of a mixed solvent of (D-1)/(D-2)/(D-3) as the solvent [D] were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).
Radiation-sensitive resin compositions (J-2) to (J-51) and (CJ-1) to (CJ-12) were prepared in the same manner as in Example 1 except that the components of the types and contents shown in the following Table 4 were used.
A composition for forming an underlayer antireflective film (“ARC66” manufactured by Brewer Science, Inc.) was applied onto a 12 inch silicon wafer using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), and then heated at 205° C. for 60 seconds to form an underlayer antireflective film having an average thickness of 100 nm. The positive radiation-sensitive resin composition for ArF exposure prepared above was applied onto the underlayer antireflective film using the spin coater, and subjected to PB (prebake) at 100° C. for 60 seconds. Thereafter, cooling was performed at 23° C. for 30 seconds to form a resist film having an average thickness of 90 nm. Subsequently, this resist film was exposed through a mask pattern of 40 nm line-and-space using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” manufactured by ASML Holding N.V.) under optical conditions of a numeral aperture (NA) of 1.35 and dipole illumination (σ=0.9/0.7). After the exposure, PEB (post exposure bake) was performed at 100° C. for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38 mass % aqueous TMAH solution as an alkaline developer. After the development, the resist film was washed with water and further dried to form a positive resist pattern (40 nm line-and-space pattern).
The sensitivity and LWR performance of each of resist patterns formed using the positive radiation-sensitive resin compositions for ArF exposure were evaluated according to the following methods. The results are shown in the following Table 5. It is to be noted that a scanning electron microscope (“CG-5000” manufactured by Hitachi High-Tech Corporation) was used for measurement of the resist pattern.
An exposure dose at which a 40 nm line-and-space pattern was formed in formation of a resist pattern using the positive radiation-sensitive resin composition for ArF exposure was defined as an optimum exposure dose, and this optimum exposure dose was defined as sensitivity (mJ/cm2). A case where the sensitivity was 25 mJ/cm2 or less was evaluated as “good”, and a case where the sensitivity exceeded 25 mJ/cm2 was evaluated as “poor”.
A 40-nm line-and-space resist pattern was formed by irradiation with the optimum exposure dose obtained in the evaluation of the sensitivity. The formed resist pattern was observed from above the pattern using the scanning electron microscope. The variation in line width was measured at 500 points in total, the value of 3σ was obtained from the distribution of the measured values, and the value of 3σ was defined as LWR (nm). A smaller value of LWR indicates smaller roughness of the line and better performance. The LWR performance was evaluated as “good” when the LWR was 3.0 nm or less, and was evaluated as “poor” when the LWR exceeded 3.0 nm.
As is apparent from the results in Table 5, the radiation-sensitive resin compositions of Examples were superior in sensitivity and LWR performance when used for ArF exposure, whereas the radiation-sensitive resin compositions of Comparative Examples were inferior in each characteristic to Examples. Therefore, when the radiation-sensitive resin compositions of Examples were used for ArF exposure, a resist pattern having high sensitivity and superior LWR performance can be formed.
100 parts by mass of (A-12) as the resin [A], 15.0 parts by mass of (B-1) as the radiation-sensitive acid generator [B], 3.0 parts by mass of (C-1) as the acid diffusion controlling agent [C], 3.0 parts by mass (solid content) of (E-5) as the high fluorine-content resin [E], and 6,110 parts by mass of a mixed solvent of (D-1)/(D-4) as the solvent [D] were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-52).
Radiation-sensitive resin compositions (J-53) to (J-62) and (CJ-13) to (CJ-16) were prepared in the same manner as in Example 52 except that the components of the types and contents shown in the following Table 6 were used.
A composition for forming an underlayer antireflective film (“ARC66” manufactured by Brewer Science, Inc.) was applied onto a 12 inch silicon wafer using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), and then heated at 205° C. for 60 seconds to form an underlayer antireflective film having an average thickness of 105 nm. The positive radiation-sensitive resin composition for EUV exposure prepared above was applied onto the underlayer antireflective film using the spin coater, and subjected to PB at 130° C. for 60 seconds. Thereafter, cooling was performed at 23° C. for 30 seconds to form a resist film having an average thickness of 55 nm. Subsequently, this resist film was exposed with an EUV exposure apparatus (“NXE3300” manufactured by ASML Holding N.V.) with an NA of 0.33 under an illumination condition of conventional illumination (s=0.89), and with a mask of imecDEFECT32FFR02. After the exposure, PEB was performed at 120° C. for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38 mass % aqueous TMAH solution as an alkaline developer, and after the development, the resist film was washed with water and further dried to form a positive resist pattern (32 nm line-and-space pattern).
The sensitivity and LWR performance of each of resist patterns formed using the positive radiation-sensitive resin compositions for EUV exposure were evaluated according to the following methods. The results are shown in the following Table 7. It is to be noted that a scanning electron microscope (“CG-5000” manufactured by Hitachi High-Tech Corporation) was used for measurement of the resist pattern.
In formation of the resist pattern using the positive radiation-sensitive resin composition for EUV exposure, an exposure dose at which a 32 nm line-and-space pattern was formed was defined as an optimum exposure dose, and this optimum exposure dose was defined as sensitivity (mJ/cm2). A case where the sensitivity was 30 mJ/cm2 or less was evaluated as “good”, and a case where the sensitivity exceeded 30 mJ/cm2 was evaluated as “poor”.
A resist pattern was formed with the mask size adjusted so as to form a 32 nm line-and-space pattern by irradiation with the optimum exposure dose obtained in the evaluation of the sensitivity. The formed resist pattern was observed from above the pattern using the scanning electron microscope. The variation in line width was measured at 500 points in total, the value of 3σ was obtained from the distribution of the measured values, and the value of 3σ was defined as LWR (nm). A smaller value of LWR indicates smaller displacement of the line and better performance. A case where the LWR performance was 3.0 nm or less was evaluated as “good”, and a case where the LWR performance exceeded 3.0 nm was evaluated as “poor”.
As is apparent from the results in Table 7, the radiation-sensitive resin compositions of Examples were superior in sensitivity and LWR performance when used for EUV exposure, whereas the radiation-sensitive resin compositions of Comparative Examples were inferior in characteristics to those of Examples.
[Preparation of Negative Radiation-Sensitive Resin Composition for ArF Exposure, and Formation and Evaluation of Resist Pattern Using this Composition]
100 parts by mass of (A-6) as the resin [A], 10.0 parts by mass of (B-5) as the radiation-sensitive acid generator [B], 2.0 parts by mass of (C-1) as the acid diffusion controlling agent [C], 1.0 part by mass (solid content) of (E-4) as the high fluorine-content resin [E], and 3,230 parts by mass of a mixed solvent of (D-1)/(D-2)/(D-3) (2240/960/30 (parts by mass)) as the solvent [D] were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-63).
A composition for forming an underlayer antireflective film (“ARC66” manufactured by Brewer Science, Inc.) was applied onto a 12 inch silicon wafer using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), and then heated at 205° C. for 60 seconds to form an underlayer antireflective film having an average thickness of 100 nm. The negative radiation-sensitive resin composition for ArF exposure (J-63) prepared above was applied onto the underlayer antireflective film using the spin coater, and subjected to PB (prebake) at 100° C. for 60 seconds. Thereafter, cooling was performed at 23° C. for 30 seconds to form a resist film having an average thickness of 90 nm. Subsequently, this resist film was exposed through a mask pattern of 40 nm hole and 105 nm pitch using an ArF excimer laser immersion exposure apparatus (“TWINSCAN XT-1900i” manufactured by ASML Holding N.V.) under optical conditions of a numeral aperture (NA) of 1.35 and annular illumination (σ=0.8/0.6). After the exposure, PEB (post exposure bake) was performed at 100° C. for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer, and dried to form a negative resist pattern (40 nm hole, 105 nm pitch).
The resist patterns formed using the negative radiation-sensitive resin compositions for ArF exposure were evaluated on sensitivity and CDU performance according to the following methods. It is to be noted that a scanning electron microscope (“CG-5000” manufactured by Hitachi High-Tech Corporation) was used for measurement of the resist pattern.
An exposure dose at which a 40 nm hole pattern was formed in formation of a resist pattern using the negative radiation-sensitive resin composition for ArF exposure was defined as an optimum exposure dose, and this optimum exposure dose was defined as sensitivity (mJ/cm2).
A resist pattern with 40 nm holes and 105 nm pitches was measured using the scanning electron microscope, and measurement was performed at any 1,800 points in total from above the pattern. The dimensional variation (3σ) was determined and taken as the CDU performance (nm). A smaller value of CDU indicates smaller variation in the hole diameter in the long period and better performance.
As a result of evaluating the resist pattern using the negative radiation-sensitive resin composition for ArF exposure as described above, the radiation-sensitive resin composition of Example 63 had good sensitivity and CDU performance even when a negative resist pattern was formed by ArF exposure.
[Preparation of Negative Radiation-Sensitive Resin Composition for EUV Exposure, and Formation and Evaluation of Resist Pattern Using this Composition]
100 parts by mass of (A-13) as the resin [A], 20.0 parts by mass of (B-6) as the radiation-sensitive acid generator [B], 10.0 parts by mass of (C-1) as the acid diffusion controlling agent [C], 7.0 parts by mass (solid content) of (E-5) as the high fluorine-content resin [E], and 6,110 parts by mass of a mixed solvent of (D-1)/(D-4) (4280/1830 (parts by mass)) as the solvent [D] were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-64).
A composition for forming an underlayer antireflective film (“ARC66” manufactured by Brewer Science, Inc.) was applied onto a 12 inch silicon wafer using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron Limited), and then heated at 205° C. for 60 seconds to form an underlayer antireflective film having an average thickness of 105 nm. The negative radiation-sensitive resin composition for EUV exposure (J-64) prepared above was applied onto the underlayer antireflective film using the spin coater, and subjected to PB at 130° C. for 60 seconds. Thereafter, cooling was performed at 23° C. for 30 seconds to form a resist film having an average thickness of 55 nm. Subsequently, this resist film was exposed with an EUV exposure apparatus (“NXE3300” manufactured by ASML Holding N.V.) with an NA of 0.33 under an illumination condition of conventional illumination (s=0.89), and with a mask of imecDEFECT32FFR02. After the exposure, PEB was performed at 120° C. for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer, and dried to form a negative resist pattern (40 nm hole, 105 nm pitch).
The resist pattern using the negative radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as in the evaluation of the resist pattern using the negative radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 64 was superior in sensitivity and CDU performance even when a negative resist pattern was formed by EUV exposure.
According to the radiation-sensitive resin composition and the resist pattern forming method described above, a resist pattern that is superior in sensitivity to exposure light and excellent in LWR performance and CDU performance can be formed. Therefore, these can be suitably used for a processing process of a semiconductor device in which micronization is expected to further progress in the future.
Obviously, numerous modifications and variations of the present invention(s) are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-197128 | Nov 2020 | JP | national |
The present application is a continuation-in-part application of PCT/JP2021/042017 filed Nov. 16, 2021, which claims priority to Japanese Patent Application No. 2020-197128 filed Nov. 27, 2020. The contents of these applications are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP21/42017 | Nov 2021 | US |
| Child | 18198971 | US |
