Patent Application
20230029535
This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2021-090241 filed in Japan on May 28, 2021, the entire contents of which are hereby incorporated by reference.
This invention relates to a positive resist composition and a pattern forming process.
To meet the demand for higher integration density and operating speed of LSIs, the effort to reduce the pattern vile is in rapid progress. As the use of 5G high-speed communications and artificial intelligence (AI) is widely spreading, high-performance devices are needed for their processing. As the advanced miniaturization technology, manufacturing of microelectronic devices at the 5-nm node by the lithography using EUV of wavelength 13.5 nm has been implemented in a mass scale. Studies are made on the application of EUV lithography to 3-nm node devices of the next generation and 2-nm node devices of the next-but-one generation.
As the feature size reduces, image blurs due to acid diffusion become a problem. To insure resolution for fine patterns with a size of 45 nm et seq., not only an improvement in dissolution contrast is important as previously reported, but the control of acid diffusion is also important as reported in Non-Patent Document 1. Since chemically amplified resist compositions are designed such that sensitivity and contrast are enhanced by acid diffusion, an attempt to minimize acid diffusion by reducing the temperature and/or time of post-exposure bake (PEB) fails, resulting in drastic reductions of sensitivity and contrast.
A triangular tradeoff relationship among sensitivity, resolution, and edge roughness (LER or LWR) has been pointed out. Specifically, a resolution improvement requires to suppress acid diffusion whereas a short acid diffusion distance leads to a decline of sensitivity.
The addition of an acid generator capable of generating a bulky acid is an effective means for suppressing acid diffusion. It was then proposed to incorporate repeat units derived from an opium salt having a polymerizable unsaturated bond in a polymer. Since this polymer functions as an acid generator, it is referred to as polymer-bound acid generator. Patent Document 1 discloses a sulfonium or iodonium salt having a polymerizable unsaturated bond, capable of generating a specific sulfonic acid. Patent Document 2 discloses a sulfonium salt having a sulfonic acid directly attached to the backbone.
Patent Documents 3 and 4 describe a resist material comprising a polymer comprising repeat units having an alicyclic group to which a nitro group or nitric ester group is bonded and repeat units having an acid labile group. The nitro group or nitric ester group is effective for suppressing acid diffusion, but the suppression of acid diffusion invites a lowering of dissolution contrast as mentioned above. It is desired to have a resist material meeting controlled acid diffusion and a high contrast.
An object of the invention is to provide a positive resist composition which exhibits a high sensitivity and resolution surpassing prior art positive resist compositions, and forms a pattern of good profile with reduced edge roughness and size variation after exposure, and a pattern forming process using the same.
Studies in search for the currently desired positive resist composition having a high resolution, reduced edge roughness and reduced size variation reveal that the acid diffusion distance must be minimized. There arise problems like drops of sensitivity and dissolution contrast, which aggravate the resolution of two-dimensional patterns such as hole patterns. Quite unexpectedly, the inventor has found that a base polymer comprising repeat units having a carboxy group whose hydrogen is substituted by a nitrobenzene ring-containing tertiary hydrocarbyl group makes it possible to enhance the dissolution contrast and at the same time, to minimize the acid diffusion distance. Better results are obtained particularly when the base polymer is used in chemically amplified positive resist compositions.
When repeat units having a carboxy group or phenolic hydroxy group whose hydrogen is substituted by an acid labile group are introduced into the base polymer for further enhancing the dissolution contrast, there is obtained a positive resist composition which has a high sensitivity, an outstandingly increased contrast of alkaline dissolution rate before and after exposure, a remarkable acid diffusion-controlling effect, and a high resolution, and forms a pattern of satisfactory profile with reduced edge roughness and improved CDU. The resist composition is suited as a micropatterning material for the fabrication of VLSIs and photomasks.
In one aspect, the invention provides a positive resist composition comprising a base polymer comprising repeat units having a carboxy group whose hydrogen is substituted by a nitrobenzene ring-containing tertiary hydrocarbyl group.
In a preferred embodiment, the repeat units have the formula (a).
Herein RA is hydrogen or methyl. X1 is a single bond, phenylene, naphthylene, or a C1-C12 linking group containing at least one moiety selected from an ester bond, ether bond and lactone ring. R is a group having the formula (a1).
Herein R1 and R2 are each independently a C1-C6 aliphatic hydrocarbyl group which may contain a heteroatom, R1 and R2 may bond together to form a ring with the carbon atom to which they are attached, R3 is hydrogen, halogen, a C1-C6 alkyl group, C1-C6 alkoxy group or C1-C6 acyloxy group, m is an integer of 1 to 4, n is 1 or 2, and the broken line designates a valence bond.
In a preferred embodiment, the base polymer further comprises repeat units of at least one type selected from repeat units having a carboxy group whose hydrogen is substituted by an acid labile group other than the nitrobenzene ring-containing tertiary hydrocarbyl group, and repeat units having a phenolic hydroxy group whose hydrogen is substituted by an acid labile group.
Preferably, the repeat units having a carboxy group whose hydrogen is substituted by an acid labile group other than the nitrobenzene ring-containing tertiary hydrocarbyl group have the formula (b1), and the repeat units having a phenolic hydroxy group whose hydrogen is substituted by an acid labile group have the formula (b2).
Herein RA is each independently hydrogen or methyl. Y1 is a single bond, phenylene group, naphthylene group, or a C1-C12 linking group containing at least one moiety selected from an ester bond, ether bond and lactone ring. Y2 is a single bond, ester bond or amide bond. Y3 is a single bond, ether bond or ester bond. R11 is an acid labile group other than the nitrobenzene ring-containing tertiary hydrocarbyl group. R12 is an acid labile group. R13 is fluorine, trifluoromethyl, cyano or a C1-C6 saturated hydrocarbyl group. R14 is a single bond or a C1-C6 alkanediyl group in which some constituent —CH2— may be replaced by an ether bond or ester bond, a is 1 or 2, b is an integer of 0 to 4, and the sum of a+b is from 1 to 5.
In a preferred embodiment, the base polymer further comprises repeat units having an adhesive group which is selected from among hydroxy, carboxy, lactone ring, carbonate bond, thiocarbonate bond, carbonyl, cyclic acetal, ether bond, ester bond sulfonic ester bond, cyan, amide bond, —O—C(═O)—S—, and —O—C(═O)—NH—.
In a preferred embodiment, the base polymer further comprises repeat units of at least one type selected from repeat units having the formulae (D1) to (d3).
Herein RA is each independently hydrogen or methyl. Z1 is a single bond, a C1-C6 aliphatic hydrocarbylene group, phenylene, naphthylene, or a C7-C1s group obtained by combining the foregoing, or —O—Z11—, —C(═O)—O—Z11— or —C(═O)—NH—Z11—, wherein Z11 is a C1-C6 aliphatic hydrocarbylene group, phenylene, naphthylene, or a C7-C18 group obtained by combining the foregoing which may contain a carbonyl moiety, ester bond, ether bond or hydroxy moiety. Z2 is a single bond or ester bond. Z3 is a single bond, —Z31—C(═O)—O—, —Z31—O— or —Z31—O—C(═O)—, wherein Z31 is a C1-C12 aliphatic hydrocarbylene group, phenylene group, or a C7-C18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond, ether bond, iodine or bromine. Z4 is a methylene, 2,2,2-trifluoro-1,1-ethanediyl or carbonyl group. Z5 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, trifluoromethyl-substituted phenylene, —C(O)—O—Z51— or —C(═O)—NH—Z51—, wherein Z31 is a C1-C6 aliphatic hydrocarbylene group, phenylene, fluorinated phenylene, or trifluoromethyl-substituted phenylene group, which may contain a carbonyl moiety, ester bond ether bond or hydroxy moiety. R21 to R28 are each independently halogen or a C1-C20 hydrocarbyl group which may contain a heteroatom, R23 and R24, or R26 and R22 may bond together to form a ring with the sulfur atom to which they are attached. M− is a non-nucleophilic counter ion.
The positive resist composition may further comprise an acid generator, an organic solvent, a quencher, and/or a surfactant.
In another aspect, the invention provides a pattern forming process comprising the steps of applying the positive resist composition defined above onto a substrate to form a resist film thereon, exposing the resist film to high-energy radiation, and developing the exposed resist film in a developer.
Typically, the high-energy radiation is i-line, ArF excimer laser, KrF excimer laser. EB, or EUV of wavelength 3 to 15 μm.
The positive resist composition has a remarkable acid diffusion-suppressing effect, a high sensitivity, and a high resolution, and forms a pattern of good profile with improved edge roughness and size variation after exposure and development. By virtue of these properties, the resist composition is fully useful in commercial application and best suited as a micropatterning material for photomasks by EB lithography or for VLSIs by EB or EUV lithography. The resist composition may be used not only in the lithography for forming semiconductor circuits, but also in the formation of mask circuit patterns, micromachines, and thin-film magnetic head circuits.
As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. “Optional” or “optionally” means that the subsequently described event or circumstances may or may not occur, and that description includes instances where the event or circumstance occurs and instances where it does not. The notation (Cn-Cm) means a group containing from n to m carbon atoms per group. In chemical formulae, the broken line designates a valence bond; Me stands for methyl, and Ac for acetyl. As used herein, the term “fluorinated” refers to a fluorine-substituted or fluorine-containing compound or group. The terms “group” and “moiety” are interchangeable.
The abbreviations and acronyms have the following meaning.
EB: electron beam
EUV: extreme ultraviolet
Mw: weight average molecular weight
Mn: number average molecular weight
Mw/Mn: molecular weight distribution or dispersity
GPC: gel permeation chromatography
PEB: post-exposure bake
PAG: photoacid generator
LWR: line width roughness
CDU: critical dimension uniformity
One embodiment of the invention is a positive resist composition comprising a base polymer comprising repeat units having a carboxy group whose hydrogen is substituted by a nitrobenzene ring-containing tertiary hydrocarbyl group. The repeat unit is also referred to as repeat unit (a), hereinafter. Since the nitrobenzene ring-containing tertiary hydrocarbyl group is fully effective for suppressing acid diffusion, a resist film having a high dissolution contrast is obtained using a base polymer comprising repeat units (a). Notably, the “tertiary hydrocarbyl group” is a group obtained by eliminating hydrogen from the tertiary carbon in a tertiary hydrocarbon.
Preferably, the repeat units (a) have the formula (a).
In formula (a), RA is hydrogen or methyl. X1 is a single bond, phenylene group, naphthylene group, or a C1-C12 linking group containing at least one moiety selected from an ester bond, ether bond and lactone ring.
In formula (a), R is a nitrobenzene ring-containing tertiary hydrocarbyl group having the formula (a1).
In formula (a1), R1 and R2 are each independently a C1-C6 aliphatic hydrocarbyl group which may contain a heteroatom. R1 and R2 may bond together to form a ring with the carbon atom to which they are attached. R3 is hydrogen, halogen, a C1-C6 alkyl group, C1-C6 alkoxy group or C1-C6 acyloxy group. The subscript m is an integer of 1 to 4, and n is 1 or 2.
The C1-C6 aliphatic hydrocarbyl group represented by R1 and R2 may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, and n-hexyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl; alkenyl groups such as vinyl, 1-propenyl, 2-propenyl, butenyl and hexenyl; cycloalkenyl groups such as cyclohexenyl; alkynyl groups such as ethynyl and butynyl; and combinations thereof. R1 and R2 are preferably selected from methyl, ethyl, isopropyl, test-butyl, cyclopentyl, cyclohexyl, vinyl, and ethynyl.
Suitable halogen atoms represented by R3 include fluorine, chlorine, bromine and iodine.
Examples of the C1-C6 alkyl group and alkyl moiety in the C1-C6 alkoxy group and C1-C6 acyloxy group, represented by R3, include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and tert-pentyl.
Examples of the group having formula (a1) are shown below, but not limited thereto.
Examples of the monomer from which repeat units having formula (a) are derived are shown below, but not limited thereto. RA and R are as defined above.
The repeat unit (a) functions as a quencher due to the inclusion of nitrogen atom. That is, the base polymer is a quencher-bound polymer. The quencher-bound polymer has the advantages of a remarkable acid diffusion-suppressing effect and improved resolution. In addition, the repeat unit (a) is an acid labile group unit because it has a tertiary ester structure. In contrast to the ordinary acid labile group unit that relies on an acid-catalyzed polarity switch, the repeat unit (a) has not only the polarity switch function, but also the acid diffusion-suppressing function. This enables to enhance dissolution contrast while suppressing acid diffusion.
For the purpose of enhancing dissolution contrast, the base polymer may further comprise repeat units having a carboxy group whose hydrogen is substituted by an acid labile group other than the nitrobenzene ring-containing tertiary hydrocarbyl group (also referred to as units (b1), hereinafter), and/or repeat units having a phenolic hydroxy group whose hydrogen is substituted by an acid labile group (also referred to as units (b2), hereinafter).
Typically, the repeat units (b1) and (b2) have the formulae (b1) and (b2), respectively.
In formulae (b1) and (b2), RA is each independently hydrogen or methyl. Y1 is a single bond, phenylene group, naphthylene group, or a C1-C12 linking group containing at least one moiety selected from an ester bond, ether bond and lactone ring. Y2 is a single bond, ester bond or amide bond. Y3 is a single bond, ether bond or ester bond R11 is an acid labile group other than the nitrobenzene ring-containing tertiary hydrocarbyl group. R12 is an acid labile group. R13 is fluorine, trifluoromethyl, cyano or a C1-C6 saturated hydrocarbyl group. R14 is a single bond or a C1-C6 alkanediyl group in which some constituent —CH2— may be replaced by an ether bond or ester bond. The subscript “a” is 1 or 2, “b” is an integer of 0 to 4, and the sum of a+b is from 1 to 5.
Examples of the monomer from which the repeat unit (b1) is derived are shown below, but not limited thereto. RA and R11 are as defined above.
Examples of the monomer from which the repeat unit (b2) is derived are shown below, but not limited thereto. RA and R12 are as defined above.
The acid labile groups represented by R11 and R12 may be selected from a variety of such groups, for example, groups of the following formulae (AL-1) to (AL-3).
In formula (AL-1), c is an integer of 0 to 6. RL1 is a C4-C20, preferably C4-C15 tertiary hydrocarbyl group, a trihydrocarbylsilyl group in which each hydrocarbyl moiety is a C1-C6 saturated one, a C4-C20 saturated hydrocarbyl group containing a carbonyl moiety, ether bond or ester bond, or a group of formula (AL-3). Notably, the tertiary hydrocarbyl group is a group obtained by eliminating hydrogen from the tertiary carbon in a tertiary hydrocarbon.
The tertiary hydrocarbyl group RL1 may be saturated or unsaturated and branched or cyclic. Examples thereof include tert-butyl, tert-pentyl, 1,1-diethylpropyl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl 1,1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, and 2-methyl-2-adamantyl. Examples of the trihydrocarbylsilyl group include trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. The saturated hydrocarbyl group containing a carbonyl moiety, ether bond or ester bond may be straight, branched or cyclic, preferably cyclic and examples thereof include 3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, 5-methyl-2-oxooxolan-5-yl, 2-tetrahydropyranyl, and 2-tetrahydrofuranyl.
Examples of the acid labile group having formula (AL-1) include tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-pentyloxycarbonyl, tert-pentyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycalbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl, 1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, and 2-tetrahydrofuranyloxycarbonylmethyl.
Other examples of the acid labile group having formula (AL-1) include groups having the formulae (AL-1)-1 to (AL-1)-10.
In formulae (AL-1)-1 to (AL-1)-10, c is as defined above. RL8 is each independently a C1-C10 saturated hydrocarbyl group or C6-C20 aryl group. RL9 is hydrogen or a C1-C10 saturated hydrocarbyl group. RL10 is a C2-C10 saturated hydrocarbyl group or C6-C20 aryl group. The saturated hydrocarbyl group may be straight, branched or cyclic.
In formula (AL-2), RL2 and RL3 are each independently hydrogen or a C1-C18, preferably C1-C10 saturated hydrocarbyl group. The saturated hydrocarbyl group may be straight, branched or cyclic and examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl and n-octyl.
RL4 is a C1-C18, preferably C1-C10 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Typical are C1-C1s saturated hydrocarbyl groups, in which some hydrogen may be substituted by hydroxy, alkoxy, oxo, amino or alkylamino. Examples of the substituted saturated hydrocarbyl group are shown below.
A pair of RL2 and RL3, RL2 and RL4, or RL3 and RL4 may bond together to form a ring with the carbon atom or carbon and oxygen atoms to which they are attached. RL2 and RL3, RL2 and RL4, or RL3 and RL4 that form a ring are each independently a C1-C18, preferably C1-C10 alkanediyl group. The ring thus formed is preferably of 3 to 10, more preferably 4 to 10 carbon atoms.
Of the acid labile groups having formula (AL-2), suitable straight or branched groups include those having formulae (AL-2)-1 to (AL-2)-69, but are not limited thereto.
Of the acid labile groups having formula (AL-2), suitable cyclic groups include tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2 yl, tetrahydropyran-2-yl, and 2-methyltetrahydropyran-2-yl.
Also included are acid labile groups having the following formulae (AL-2a) and (AL-2b). The base polymer may be crosslinked within the molecule or between molecules with these acid labile groups.
In formulae (AL-2a) and (AL-2b), RL11 and RL12 are each independently hydrogen or a C1-C8 saturated hydrocarbyl group which may be straight, branched or cyclic. Also, RL11 and RL12 may bond together to form a ring with the carbon atom to which they are attached, and in this case. RL11 and RL12 are each independently a C1-C8 alkanediyl group. RL13 is each independently a C1-C10 saturated hydrocarbylene group which may be straight, branched or cyclic. The subscripts d and e are each independently an integer of 0 to 10, preferably 0 to 5, and f is an integer of 1 to 7, preferably 1 to 3.
In formulae (AL-2a) and (AL-2b), LA is a (f+1)-valent C1-C50 aliphatic saturated hydrocarbon group, (f+1)-valent C3-C50 alicyclic saturated hydrocarbon group, (f+1)-valent C6-C50 aromatic hydrocarbon group or (f+1)-valent C3-C50 heterocyclic group. In these groups, some constituent —CH2— may be replaced by a heteroatom-containing moiety, or some hydrogen may be substituted by a hydroxy, carboxy, acyl moiety or fluorine. LA is preferably a C1-C20 saturated hydrocarbylene, saturated hydrocarbon group (e.g., tri- or tetravalent saturated hydrocarbon group), or C6-C30 arylene group. The saturated hydrocarbon group may be straight, branched or cyclic. LB is —C(═O)—O—, —NH—C(═O)—O— or —NH—C(═O)—NH—.
Examples of the crosslinking acetal groups having formulae (AL-2a) and (AL-2b) include groups having the formulae (AL-2)-70 to (AL-2)-77.
In formula (AL-3), RL5, RL6 and RL7 are each independently a C1-C20 hydrocarbyl group which may contain a heteroatom such as oxygen, sulfur, nitrogen or fluorine. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include C1-C20 alkyl groups, C3-C20 cyclic saturated hydrocarbyl groups. C2-C20 alkenyl groups, C3-C20 cyclic unsaturated hydrocarbyl groups, and C6-C10 aryl groups. A pair of RL5 and RL6, RL5 and RL7, or RL6 and RL7 may bond together to form a C3-C20 aliphatic ring with the carbon atom to which they are attached.
Examples of the group having formula (AL-3) include tert-butyl, 1,1-diethylpropyl, 1-ethylnorbornyl, 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-isopropylcyclopentyl, 1 methylcyclohexyl, 2-(2-methyl)adamantyl, 2-(2-ethyl)adamantyl, and tert-pentyl.
Examples of the group having formula (AL-3) also include groups having the formulae (AL-3)-1 to (AL-3)-19.
In formulae (AL-3)-1 to (AL-3)-19, RL14 is each independently a C1-C8 saturated hydrocarbyl group or C6-C20 aryl group. RL15 and RL17 are each independently hydrogen or a C1-C20 saturated hydrocarbyl group. RL16 is a C6-C20 aryl group. The saturated hydrocarbyl group may be straight, branched or cyclic. Typical of the aryl group is phenyl. RF is fluorine or trifluoromethyl, and g is an integer of 1 to 5.
Other examples of the acid labile group having formula (AL-3) include groups having the formulae (AL-3)-20 and (AL-3)-21. The base polymer may be crosslinked within the molecule or between molecules with these acid labile groups.
In formulae (AL-3)-20 and (AL-3)-21. RL14 is as defined above. RL18 is a (h+1)-valent C1-C20 saturated hydrocarbylene group or (h+1)-valent C6-C20 arylene group, which may contain a heteroatom such as oxygen, sulfur or nitrogen. The saturated hydrocarbylene group may be straight, branched or cyclic. The subscript h is an integer of 1 to 3.
Examples of the monomer from which repeat units containing an acid labile group of formula (AL-3) are derived include (meth)acrylates (inclusive of exo-form structure) having the formula (AL-3)-22.
In formula (AL-3)-22, RA is as defined above. RLc1 is a C1-C8 saturated hydrocarbyl group or an optionally substituted C6-C20 aryl group; the saturated hydrocarbyl group may be straight, branched or cyclic. RLc2 to RLc11 are each independently hydrogen or a C1-C15 hydrocarbyl group which may contain a heteroatom; oxygen is a typical heteroatom. Suitable hydrocarbyl groups include C1-C15 alkyl groups and C6-C15 aryl groups. Alternatively, a pair of RLc2 and RLc3, RLc4 and RLc6, RLc4 and RLc7, RLc5 and RLc7, RLc5 and RLc11, RLc6 and RLc10, RLc8 and RLc9, or RLc9 and RLc10, taken together, may form a ring with the carbon atom to which they are attached, and in this event, the ring-forming group is a C1-C15 hydrocarbylene group which may contain a heteroatom. Also, a pair of RLc2 and RLc11, RLc8 and RLc11, or RLc4 and RLc6 which are attached to vicinal carbon atoms may bond together directly to form a double bond. The formula also represents an enantiomer.
Examples of the monomer from which repeat units having formula (AL-3)-22 are derived are described in U.S. Pat. No. 6,448,420 (JP-A 2000-327633). Illustrative non-limiting examples of suitable monomers are given below. RA is as defined above.
Also included in the repeat units having an acid labile group of formula (AL-3) are repeat units of (meth)acrylate having a furandiyl, tetrahydrofurandiyl or oxanorbornanediyl group as represented by the following formula (AL-3)-23.
In formula (AL-3)-23, RA is as defined above. RLc12 and RLc13 are each independently a C1-C10 hydrocarbyl group, or RLc12 and RLc13, taken together, may form an aliphatic ring with the carbon atom to which they are attached. RLc14 is furandiyl, tetrahydrofurandiyl or oxanorbornanediyl. RLc15 is hydrogen or a C1-C10 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be straight, branched or cyclic, and examples thereof include C1-C10 saturated hydrocarbyl groups.
Examples of the monomer from which the repeat units having formula (AL-3)-23 are derived are shown below, but not limited thereto. Herein RA is as defined above.
The base polymer may further comprise repeat units (c) having an adhesive group. The adhesive group is selected from hydroxy, carboxy, lactone ring, carbonate bond, thiocarbonate bond carbonyl, cyclic acetal, ether bond, ester bond, sulfonic ester bond, cyano, amide bond, —O—C(═O)—S— and —O—C(═O)—NH—.
Examples of the monomer from which repeat units (c) are derived are given below, but not limited thereto. Herein RA is as defined above.
In a further embodiment, the base polymer may comprise repeat units (d) of at least one type selected from repeat units having the following formulae (d1), (d2) and (d3). These units are also referred to as repeat units (d1), (d2) and (d3).
In formulae (d1) to (d3), RA is each independently hydrogen or methyl. Z1 is a single bond, C1-C6 aliphatic hydrocarbylene group, phenylene, naphthylene, or a C7-C1s group obtained by combining the foregoing, or —O—Z11—, —C(═O)—O—Z11— or —C(═O)—NH—Z11—, wherein Z11 is a C1-C6 aliphatic hydrocarbylene group, phenylene, naphthylene, or a C7-C18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond, ether bond or hydroxy moiety. Z2 is a single bond or ester bond. Z3 is a single bond, —Z31—C(═O)—O—, —Z31—O—, —Z31—O—, or —Z31—O—C(═O)—, wherein Z31 is a C1-C12 aliphatic hydrocarbylene group, phenylene group, or a C7-C18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond ether bond, bromine or iodine. Z4 is methylene, 2,2,2-trifluoro-1,1-ethanediyl or carbonyl. Z5 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, trifluoromethyl-substituted phenylene, —O—Z51—, —C(═O)—O—Z51—, or —C(═O)—NH—Z51—, wherein Z51 is a C1-C6 aliphatic hydrocarbylene group, phenylene, fluorinated phenylene, or trifluoromethyl-substituted phenylene group, which may contain a carbonyl moiety, ester bond, ether bond, halogen or hydroxy moiety. The aliphatic hydrocarbylene group represented by Z1, Z11, Z31 and Z51 may be saturated or unsaturated and straight, branched or cyclic.
In formulae (d1) to (d3), R21 to R28 are each independently halogen or a C1-C20 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as will be exemplified later for R101 to R105 in formulae (1-1) and (1-2). A pair of R23 and R24, or R26 and R27 may bond together to form a ring with the sulfur atom to which they are attached. Examples of the ring are as will be exemplified later for the ring that R101 and R102 in formula (I-1), taken together, form with the sulfur atom to which they are attached.
In formula (d1), M− is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride and bromide ions; fluoroallylsulfonate ions such as triflate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate; arylsulfonate ions such as tosylate, benzenesulfonate, 4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate; alkylsulfonate ions such as mesylate and butanesulfonate; imide ions such as bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide and bis(perfluorobutylsulfonyl)imide; methide ions such as tris(trifluoromethylsulfonyl)methide and tris(perfluoroethylsulfonyl)methide.
Also included are sulfonate ions having fluorine substituted at α-position as represented by the formula (d1-1) and sulfonate ions having fluorine substituted at α-position and trifluoromethyl at n-position as represented by the formula (d1-2).
In formula (d1-1), R31 is hydrogen or a C1-C20 hydrocarbyl group which may contain an ether bond, ester bond, carbonyl moiety, lactone ring, or fluorine atom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as will be exemplified later for the hydrocarbyl group R111 in formula (1A′).
In formula (d1-2), R3′ is hydrogen, or a C1-C30 hydrocarbyl group or C2-C30 hydrocarbylcarbonyl group, which may contain an ether bond, ester bond, carbonyl moiety or lactone ring. The hydrocarbyl group and the hydrocarbyl moiety in the hydrocarbylcarbonyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as will be exemplified later for the hydrocarbyl group R111 in formula (1A′).
Examples of the cation in the monomer from which repeat unit (d1) is derived are shown below, but not limited thereto. RA is as defined above.
Examples of the cation in the monomer from which repeat unit (d2) or (d3) is derived are as will be exemplified later for the cation in the sulfonium salt having formula (1-1).
Examples of the anion in the monomer from which repeat unit (d2) is derived are shown below, but not limited thereto. RA is as defined above.
Examples of the anion in the monomer from which repeat unit (d3) is derived are shown below, but not limited thereto. RA is as defined above.
Repeat units (d1) to (d3) have the function of acid generator. The attachment of an acid generator to the polymer main chain is effective in restraining acid diffusion, thereby preventing a reduction of resolution due to blur by acid diffusion. Also, LWR and CDU are improved since the acid generator is uniformly distributed. When a base polymer comprising repeat units (d) is used, that is, in the case of polymer-bound acid generator, an acid generator of addition type (to be described later) may be omitted.
Besides the repeat units described above, the base polymer may further comprise repeat units (e) which are derived from styrene, vinylnaphthalene, indene, acenaphthylene, coumarin, and coumarone.
In the base polymer comprising repeat units (a), (b1), (b2), (c), (d1), (d2), (d3), and (e), a fraction of these omits is: preferably 0<a<1.0, 0≤b1≤0.9, 0≤b2≤0.9, 0≤b1+b2≤0.9, 0≤c≤0.9, 0≤d1≤0.5, 0≤d2≤0.5, 0≤d3≤0.5, 0≤d1+d2+d3≤0.5, and 0≤e≤0.5; more preferably 0.01≤a≤0.8, 0≤b1≤0.8, 0≤b2≤0.8, 0≤b1+b2≤0.8, 0≤c≤0.8, 0≤d1≤0.4, 0≤d2≤0.4, 0≤d3≤0.4, 0≤d1+d2+d3≤0.4, and 0≤e≤0.4; and even more preferably 0.02≤a≤0.7, 0≤b1≤0.7, 0≤b2≤0.7, 0b1+b2≤0.7, 0≤c≤0.7, 0≤d1≤0.3, 0≤d2≤0.3, 0≤d3≤0.3, 0≤d1+d2+d3≤0.3, and 0≤e≤0.3. Notably, a+b1+b2+c+d1+d2+d3+e=1.0.
The base polymer may be synthesized by any desired methods, for example, by dissolving one or more monomers selected from the monomers corresponding to the foregoing repeat units in an organic solvent, adding a radical polymerization initiator thereto, and heating for polymerization. Examples of the organic solvent which can be used for polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of the polymerization initiator used herein include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. Preferably the reaction temperature is 50 to 80° C., and the reaction time is 2 to 100 hours, more preferably 5 to 20 hours.
In the case of a monomer having a hydroxy group, the hydroxy group may be replaced by an acetal group susceptible to deprotection with acid, typically ethoxyethoxy, prior to polymerization, and the polymerization be followed by deprotection with weak acid and water. Alternatively, the hydroxy group may be replaced by an acetyl, formyl, pivaloyl or similar group prior to polymerization, and the polymerization be followed by alkaline hydrolysis.
When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, an alternative method is possible. Specifically, acetoxystyrene or acetoxyvinylnaphthalene is used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group is deprotected by alkaline hydrolysis, for thereby converting the polymer product to hydroxystyrene or hydroxyvinylnaphthalene. For alkaline hydrolysis, a base such as aqueous ammonia or triethylamine may be used. Preferably the reaction temperature is −20° C., to 100° C., more preferably 0° C., to 60° C., and the reaction time is 0.2 to 100 hours, more preferably 0.5 to 20 hours.
The base polymer should preferably have a weight average molecular weight (Mw) in the range of 1,000 to 500.000, and more preferably 2,000 to 30,000, as measured by GPC versus polystyrene standards using tetrahydrofuran (THF) solvent. With too low a Mw, the resist composition may become less heat resistant. A polymer with too high a Mw may lose alkaline solubility and give rise to a footing phenomenon after pattern formation.
If a base polymer has a wide molecular weight distribution or dispersity (Mw/Mn), which indicates the presence of lower and higher molecular weight polymer fractions, there is a possibility that foreign matter is left on the pattern or the pattern profile is degraded. The influences of Mw and Mw/Mn become stronger as the pattern rule becomes finer. Therefore, the base polymer should preferably have a narrow dispersity (Mw/Mn) of 1.0 to 2.0, especially 1.0 to 1.5, in order to provide a resist composition suitable for micropatterning to a small feature size.
The base polymer may be a blend of two or more polymers which differ in compositional ratio, Mw or Mw/Mn. It may also be a blend of a polymer comprising repeat units (a) and a polymer comprising repeat units (b1) and/or (b2), but not repeat units (a).
The positive resist composition may comprise an acid generator capable of generating a strong acid (referred to as acid generator of addition type, hereinafter). As used herein, the term “strong acid” refers to a compound having a sufficient acidity to induce deprotection reaction of an acid labile group on the base polymer.
The acid generator is typically a compound (PAG) capable of generating an acid upon exposure to actinic ray or radiation. Although the PAG used herein may be any compound capable of generating an acid upon exposure to high-energy radiation, those compounds capable of generating sulfonic acid, imide acid (imidic acid) or methide acid are preferred. Suitable PACs include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate acid generators. Exemplary PAGs are described in JP-A 2008-111103, paragraphs [0122]-[0142] (U.S. Pat. No. 7,537,880).
As the PAG used herein, sulfonium salts having the formula (1-1) and iodonium salts having the formula (1-2) are also preferred.
In formulae (1-1) and (1-2), R101 to R105 are each independently halogen or a C1-C20 hydrocarbyl group which may contain a heteroatom.
Suitable halogen atoms include fluorine, chlorine, bromine and iodine. The C1-C20 hydrocarbyl group represented by R101 to R105 may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl and icosyl; C3-C20 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl and adamantyl; C2-C20 alkenyl groups such as vinyl, propenyl, butenyl and hexenyl; C2-C20 alkynyl groups such as ethynyl, propynyl and butynyl; C3-C20 cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl and norbornenyl; C6-C20 aryl groups such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl and tert-butylnaphthyl; C7-C20 aralkyl groups such as benzyl and phenethyl; and combinations thereof.
Also included are substituted forms of the foregoing groups in which some or all of the hydrogen atoms are substituted by a moiety containing a heteroatom such as oxygen, sulfur, nitrogen or halogen, or some constituent —CH2— is replaced by a moiety containing a heteroatom such as oxygen, sulfur or nitrogen, so that the group may contain a hydroxy moiety, fluorine, chlorine, bromine, iodine, cyano moiety, nitro moiety, carbonyl moiety, ether bond, ester bond, sulfonic ester bond, carbonate moiety, lactone ring, sultone ring, carboxylic anhydride (—C(═O)—O—C(═O))—) or haloalkyl moiety.
A pair of R101 and R102 may bond together to form a ring with the sulfur atom to which they are attached. Preferred are those rings of the structure shown below.
Herein, the broken line denotes a point of attachment to R103.
Examples of the cation in the sulfonium salt having formula (1-1) are shown below, but not limited thereto.
Examples of the cation in the iodonium salt having formula (1-2) are shown below, but not limited thereto.
In formulae (1-1) and (1-2), Xa− is an anion of the following formula (1A), (1B), (1C) or (1D).
In formula (1A), Rfa is fluorine or a C1-C40 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as will be exemplified later for hydrocarbyl group R111 in formula (1A′).
Of the anions of formula (1A), a structure having formula (1A′) is preferred.
In formula (1A′), RHF is hydrogen or trifluoromethyl, preferably trifluoromethyl.
R111 is a C1-C38 hydrocarbyl group which may contain a heteroatom. Suitable heteroatoms include oxygen, nitrogen, sulfur and halogen, with oxygen being preferred. Of the hydrocarbyl groups, those of 6 to 30 carbon atoms are preferred because a high resolution is available in fine pattern formation. The hydrocarbyl group R111 may be saturated or unsaturated and straight, branched or cyclic. Suitable hydrocarbyl groups include C1-C3a alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, icosanyl; C3-C38 cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, norbornylmethyl, tricyclodecanyl, tetracyclododecanyl, tetracyclododecanylmethyl, dicyclohexylmethyl; C2-C38 unsaturated aliphatic hydrocarbyl groups such as allyl and 3-cyclohexenyl; C5-C38 aryl groups such as phenyl, 1-naphthyl, 2-naphthyl; C7-C38 aralkyl groups such as benzyl and diphenylmethyl; and combinations thereof.
In these groups, some or all of the hydrogen atoms may be substituted by a moiety containing a heteroatom such as oxygen, sulfur, nitrogen or halogen, or some constituent —CH2— may be replaced by a moiety containing a heteroatom such as oxygen, sulfur or nitrogen, so that the group may contain a hydroxy, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether bond, ester bond, sulfonic ester bond, carbonate bond lactone ring, sultone ring, carboxylic anhydride (—C(═O)—O—C(═O)—) or haloalkyl moiety. Examples of the heteroatom-containing hydrocarbyl group include tetrahydrofuryl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo−1-adamantyl, and 3-oxocyclohexyl.
With respect to the synthesis of the sulfonium salt having an anion of formula (1A′), reference is made to JP-A 2007-145797, JP-A 2008-106045, JP-A 2009-007327, and JP-A 2009-258695. Also useful are the sulfonium salts described in JP-A 2010-215608, JP-A 2012-041320. JP-A 2012-106986, and JP-A 2012-153644.
Examples of the anion having formula (1A) are as exemplified for the anion having formula (1A) in US 20180335696 (JP-A 2018-197853).
In formula (1B), Rfb1 and Rfb2 are each independently fluorine or a C1-C40 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Suitable hydrocarbyl groups are as exemplified above for R111 in formula (1A′). Preferably Rfb1 and Rfb2 each are fluorine or a straight C1-C4 fluorinated alkyl group. A pair of Rfb1 and Rfb2 may bond together to form a ring with the linkage (—CF2—SO2—N−—SO2—CF2—) to which they are attached, and the ring-forming pair is preferably a fluorinated ethylene or fluorinated propylene group.
In formula (1C), Rfc1, Rfc2 and Rfc3 are each independently fluorine or a C1-C40 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Suitable hydrocarbyl groups are as exemplified above for R111 in formula (1A′). Preferably Rfc1, Rfc2 and Rfc3 each are fluorine or a straight C1-C4 fluorinated alkyl group. A pair of Rfc1 and Rfc2 may bond together to form a ring with the linkage (—CF2—SO2—C−—SO2—CF2—) to which they are attached, and the ring-forming pair is preferably a fluorinated ethylene or fluorinated propylene group.
In formula (1D), Rfd is a C1-C40 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Suitable hydrocarbyl groups are as exemplified above for R111.
With respect to the synthesis of the sulfonium salt having an anion of formula (1D), reference is made to JP-A 2010-215608 and JP-A 2014-133723.
Examples of the anion having formula (1D) are as exemplified for the anion having formula (1D) in US 20180335696 (JP-A 2018-197853).
The compound having the anion of formula (1D) has a sufficient acid strength to cleave acid labile groups in the base polymer because it is free of fluorine at α-position of sulfo group, but has two trifluoromethyl groups at I3-position. Thus the compound is a useful PAG.
Also compounds having the formula (2) are useful as the PAG.
In formula (2), R201 and R202 are each independently halogen or a C1-C30 hydrocarbyl group which may contain a heteroatom. R is a C1-C30 hydrocarbylene group which may contain a heteroatom. A pair of R201 and R202, or R201 and R203 may bond together to form a ring with the sulfur atom to which they are attached. Exemplary rings are the same as described above for the ring that R101 and R102 in formula (1-1), taken together, form with the sulfur atom to which they are attached.
The hydrocarbyl groups R201 and R202 may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohex ylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.02,6]decanyl, and adamantyl; C6-C30 aryl groups such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, tert-butylnaphthyl, and anthracenyl; and combinations thereof. In these groups, some or all of the hydrogen atoms may be substituted by a moiety containing a heteroatom such as oxygen, sulfur, nitrogen or halogen, or some constituent —CH2— may be replaced by a moiety containing a heteroatom such as oxygen, sulfur or nitrogen, so that the group may contain a hydroxy, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether bond, ester bond, sulfonic ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (—C(═O)—O—C(O)—) or haloalkyl moiety.
The hydrocarbylene group R203 may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include C1-C30 alkanediyl groups such as methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, and heptadecane-1,17-diyl; C3-C30 cyclic saturated hydrocarbylene groups such as cyclopentanediyl, cyclohexanediyl, norbornanediyl and adamantanediyl: C6-C30 arylene groups such as phenylene, methylphenylene, ethylphenylene, n-propylphenylene, isopropylphenylene, n-butylphenylene, isobutylphenylene, sec-butylphenylene, tert-butylphenylene, naphthylene, methylnaphthylene, ethylnaphthylene, n-propylnaphthylene, isopropylnaphthylene, n-butylnaphthylene, isobutylnaphthylene, sec-butylnaphthylene and tert-butylnaphthylene: and combinations thereof. In these gimps, some or all of the hydrogen atoms may be substituted by a moiety containing a heteroatom such as oxygen, sulfur, nitrogen or halogen, or some constituent —CH2— may be replaced by a moiety containing a heteroatom such as oxygen, sulfur or nitrogen, so that the group may contain a hydroxy, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether bond, ester bond, sulfonic ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (—C(═O)—O—C(═O)—) or haloalkyl moiety. Of the heteroatoms, oxygen is preferred.
In formula (2), LC is a single bond, ether bond or a C1-C20 hydrocarbylene group which may contain a heteroatom. The hydrocarbylene group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as exemplified above for R203.
In formula (2), XA, XB, XC and XD are each independently hydrogen, fluorine or trifluoromethyl, with the proviso that at least one of XA, XB, XC and XD is fluorine or trifluoromethyl.
In formula (2), k is an integer of 0 to 3.
Of the PAGs having formula (2), those having formula (2′) are preferred
In formula (2′), LC is as defined above. RHF is hydrogen or trifluoromethyl, preferably trifluoromethyl. R301, R302 and R303 are each independently hydrogen or a C1-C20 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as exemplified above for R111 in formula (1A′). The subscripts x and y are each independently an integer of 0 to 5, and z is an integer of 0 to 4.
Examples of the PAG having formula (2) are as exemplified for the PAG having formula (2) in JP-A 2017-026980.
Of the foregoing PAGs, those having an anion of formula (1A′) or (1D) are especially preferred because of reduced acid diffusion and high solubility in the solvent. Also those having formula (2′) are especially preferred because of extremely reduced acid diffusion.
Also a sulfonium or iodonium salt having an anion containing an iodized or brominated aromatic ring may be used as the PAG. Suitable are sulfonium and iodonium salts having the formulae (3-1) and (3-2).
In formulae (3-1) and (3-2), p is an integer of 1 to 3, q is an integer of 1 to 5, and r is an integer of 0 to 3, and 1≤q+r+≤5. Preferably, q is 1, 2 or 3, more preferably 2 or 3, and r is 0, 1 or 2.
In formulae (3-1) and (3-2). XBI is iodine or bromine, and may be the same or different when p and/or q is 2 or more.
L1 is a single bond, ether bond, ester bond, or a C1-C6 saturated hydrocarbylene group which may contain an ether bond or ester bond. The saturated hydrocarbylene group may be straight, branched or cyclic.
L2 is a single bond or a C1-C20 divalent linking group when p is 1, and a C1-C20 (p+1)-valent linking group which may contain oxygen, sulfur or nitrogen when p is 2 or 3.
R401 is a hydroxy group, carboxy group, fluorine, chlorine, bromine, amino group, or a C1-C219 hydrocarbyl, C1-C20 hydrocarbyloxy, C2-C20 hydrocarbylcarbonyl, C2-C20 hydrocarbyloxycarbonyl, C2-C20 hydrocarbylcarbonyloxy or C1-C20 hydrocarbylsulfonyloxy group, which may contain fluorine, chlorine, bromine, hydroxy, amino or ether bond, or —N(R401A)(R401B), —N(R401C)—C(═O)R401D or —N(R401C)—C(═O)—O—R401D. R401A and R401B are each independently hydrogen or a C1-C6 saturated hydrocarbyl group. R401C is hydrogen or a C1-C6 saturated hydrocarbyl group which may contain halogen, hydroxy, C1-C6 saturated hydrocarbyloxy. C2-C6 saturated hydrocarbylcarbonyl or C2-C6 saturated hydrocarbylcarbonyloxy moiety. R401D is a C1-C16 aliphatic hydrocarbyl group, C6-C14 aryl group or C7-C15 aralkyl group, which may contain halogen, hydroxy, C1-C6 saturated hydrocarbyloxy, C2-C6 saturated hydrocarbylcarbonyl or C2-C6 saturated hydrocarbylcarbonyloxy moiety. The aliphatic hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. The saturated hydrocarbyl, saturated hydrocarbyloxy, saturated hydrocarbyloxycarbonyl, saturated hydrocarbylcarbonyl, and saturated hydrocarbylcarbonyloxy groups may be straight, branched or cyclic. Groups R401 may be the same or different when p and/or r is 2 or more. Of these, R401 is preferably hydroxy, —N(R401C)—C(═O)—R401D, N(R401C)—C(═O)—O—R401D, fluorine, chlorine, bromine, methyl or methoxy.
In formulae (3-1) and (3-2), Rf1 to Rf4 are each independently hydrogen, fluorine or trifluoromethyl, at least one of RP to RP is fluorine or trifluoromethyl, or Rf1 and Rf2, taken together, may form a carbonyl group. Preferably, both Rf3 and Rf4 are fluorine.
R402 to R406 are each independently halogen or a C1-C20 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include those exemplified above for the hydrocarbyl groups R101 to R105 in formulae (1-1) and (1-2). In these groups, some or all of the hydrogen atoms may be substituted by hydroxy, carboxy, halogen, cyano, nitro, mercapto, sultone, sulfone, or sulfonium salt-containing moieties, and some constituent —CH2— may be replaced by an ether bond, ester bond, carbonyl moiety, amide bond, carbonate bond or sulfonic ester bond. R402 and R403 may bond together to form a ring with the sulfur atom to which they are attached. Exemplary rings are the same as described above for the ring that R101 and R102 in formula (1-1), taken together, form with the sulfur atom to which they are attached.
Examples of the cation in the sulfonium salt having formula (3-1) include those exemplified above as the cation in the sulfonium salt having formula (1-1). Examples of the cation in the iodonium salt having formula (3-2) include those exemplified above as the cation in the iodonium salt having formula (1-2).
Examples of the anion in the onium salts having formulae (3-1) and (3-2) are shown below, but not limited thereto. Herein XBI is as defined above.
When used, the acid generator of addition type is preferably added in an amount of 0.1 to 50 parts, and more preferably 1 to 40 parts by weight per 100 parts by weight of the base polymer. The resist composition functions as a chemically amplified resist composition when the base polymer includes repeat units (d) and/or the acid generator of addition type is contained.
An organic solvent may be added to the resist composition. The organic solvent used herein is not particularly limited as long as the foregoing and other components are soluble therein. Examples of the organic solvent are described in JP-A 2008-111103, paragraphs [0144]-[0145] (U.S. Pat. No. 7,537,880). Exemplary solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2 n-pentyl ketone and 2-heptanone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol (DAA); ethers such as propylene glycol monomethyl ether (PG's), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; and lactones such as γ-butyrolactone, which may be used alone or in admixture.
The organic solvent is preferably added in an amount of 100 to 10,000 parts, and more preferably 200 to 8,000 parts by weight per 100 parts by weight of the base polymer.
The positive resist composition may contain a quencher. As used herein, the quencher refers to a compound capable of trapping the acid generated by the acid generator in the resist composition to prevent the acid from diffusing to the unexposed region.
The quencher is typically selected from conventional basic compounds. Conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds with carboxy group, nitrogen-containing compounds with sulfonyl group, nitrogen-containing compounds with hydroxy group, nitrogen-containing compounds with hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, imide derivatives, and carbamate derivatives. Also included are primary, secondary, and tertiary amine compounds, specifically amine compounds having a hydroxy group, ether bond, ester bond, lactone ring, cyano group, or sulfonic ester bond as described in JP-A 2008-111103, paragraphs [0146]-[0164], and compounds having a carbamate group as described in JP 3790649. Addition of a basic compound may be effective for further suppressing the diffusion rate of acid in the resist film or correcting the pattern profile.
Onium salts such as sulfonium, iodonium and ammonium salts of sulfonic acids which are not fluorinated at α-position as described in U.S. Pat. No. 8,795,942 (JP-A 2008-158339) and similar curium salts of carboxylic acid may also be used as the quencher. While an α-fluorinated sulfonic acid, imide acid, and methide acid are necessary to deprotect the acid labile group of carboxylic acid ester, an α-non-fluorinated sulfonic acid and a carboxylic acid are released by salt exchange with an α-non-fluorinated onium salt. An α-non-fluorinated sulfonic acid and a carboxylic acid function as a quencher because they do not induce deprotection reaction.
Examples of the quencher include a compound (onium salt of α-non-fluorinated sulfonic acid) having the formula (4) and a compound (onium salt of carboxylic acid) having the formula (5).
In formula (4), R501 is hydrogen or a C1-C40 hydrocarbyl group which may contain a heteroatom, exclusive of the hydrocarbyl group in which the hydrogen bonded to the carbon atom at α-position of the sulfone group is substituted by fluorine or fluoroalkyl moiety.
The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof include C1-C40 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl: C3-Go cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.02,6]decanyl, adamantyl, and adamantylmethyl; C2-C40 alkenyl groups such as vinyl, allyl, propenyl, butenyl and hexenyl; C3-C40 cyclic unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl; C6-C40 aryl groups such as phenyl, naphthyl, alkylphenyl groups (e.g., 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 4-n-butylphenyl), dialkylphenyl groups (e.g., 2,4-dimethylphenyl and 2,4,6-triisopropylphenyl), alkylnaphthyl groups (e.g., methylnaphthyl and ethylnaphthyl), dialkylnaphthyl groups (e.g., dimethylnaphthyl and diethylnaphthyl); and C7-C40 aralkyl groups such as benzyl, 1-phenylethyl and 2-phenylethyl.
In these groups, some or all hydrogen may be substituted by a moiety containing a heteroatom such as oxygen, sulfur, nitrogen or halogen, and some constituent —CH2— may be replaced by a moiety containing a heteroatom such as oxygen, sulfur or nitrogen, so that the group may contain a hydroxy moiety, cyano moiety, carbonyl moiety, ether bond, ester bond, sulfonic ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (—C(═O)—O—C(O)—), or haloalkyl moiety. Suitable heteroatom-containing hydrocarbyl groups include heteroaryl groups such as thienyl and indolyl; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-test-butoxyphenyl, 3-tert-butoxyphenyl; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl and n-butoxynaphthyl; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl: and aryloxoalkyl groups, typically 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl and 2-(2-naphthyl)-2-oxoethyl.
In formula (5), R502 is a C1-C40 hydrocarbyl group which may contain a heteroatom. Examples of the hydrocarbyl group R502 are as exemplified above for the hydrocarbyl group R501. Also included are fluorinated alkyl groups such as trifluoromethyl, trifluoroethyl, 2,2,2-trifluoro-1 methyl-1-hydroxyethyl, 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl, and fluorinated aryl groups such as pentafluorophenyl and 4-trifluoromethylphenyl.
In formulae (4) and (5), Mq+ is an onium cation. The opium cation is preferably selected from sulfonium, iodonium and ammonium cations, more preferably sulfonium and iodonium cations. Exemplary sulfonium cations are as exemplified above for the cation in the sulfonium salt having formula (1-1). Exemplary iodonium cations are as exemplified above for the cation in the iodonium salt having formula (1-2).
A sulfonium salt of iodized benzene ring-containing carboxylic acid having the formula (6) is also useful as the quencher.
In formula (6), R601 is hydroxy, fluorine, chlorine, bromine, amino, nitro, cyano, or a C1-C6 saturated hydrocarbyl, C1-C6 saturated hydrocarbyloxy, C2-C6 saturated hydrocarbylcarbonyloxy or C1-C4 saturated hydrocarbylsulfonyloxy group, in which some or all hydrogen may be substituted by halogen, or —N(R601A)—C(═O)—R601B, or —N(R601A)—C(═O)—O—R601B. R601A is hydrogen or a C1-C6 saturated hydrocarbyl group. R601B is a C1-C6 saturated hydrocarbyl or C2-C8 unsaturated aliphatic hydrocarbyl group.
In formula (6), x′ is an integer of 1 to 5, y′ is an integer of 0 to 3, and z′ is an integer of 1 to 3. L11 is a single bond, or a C1-C20 (z′+1)-valent linking group which may contain at least one moiety selected from ether bond carbonyl moiety, ester bond, amide bond, sultone ring, lactam ring, carbonate bond, halogen, hydroxy moiety, and carboxy moiety. The saturated hydrocarbyl, saturated hydrocarbyloxy, saturated hydrocarbylcarbonyloxy, and saturated hydrocarbylsulfonyloxy groups may be straight, branched or cyclic. Groups R601 may be the same or different when y′ and/or z′ is 2 or 3.
In formula (6), R602, R603 and R604 are each independently halogen, or a C1-C20 hydrocarbyl group which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated and straight, branched or cyclic. Examples thereof are as exemplified above for the hydrocarbyl groups R101 to R105 in formulae (1-1) and (1-2). In these groups, some or all hydrogen may be substituted by hydroxy, carboxy, halogen, oxo, cyano, nitro, sultone, sulfone, or sulfonium salt-containing moiety, or some constituent —CH2— may be replaced by an ether bond, ester bond, carbonyl moiety, amide bond, carbonate moiety or sulfonic ester bond. Also R602 and R603 may bond together to form a ring with the sulfur atom to which they are attached.
Examples of the compound having formula (6) include those described in U.S. Pat. No. 10,295,904 (JP-A 2017-219836). Since iodine is highly absorptive to EUV of wavelength 13.5 inn, it generates secondary electrons during exposure, with the energy of secondary electrons being transferred to the acid generator. This promotes the decomposition of the quencher, contributing to a higher sensitivity.
Also useful are quenchers of polymer type as described in U.S. Pat. No. 7,598,016 (JP-A 2008-239918). The polymeric quencher segregates at the resist surface and thus enhances the rectangularity of resist pattern. When a protective film is applied as is often the case in the immersion lithography, the polymeric quencher is also effective for preventing a film thickness loss of resist pattern or rounding of pattern top.
When used, the quencher is preferably added in an amount of 0 to 5 parts, more preferably 0 to 4 parts by weight per 100 pacts by weight of the base polymer. The quencher may be used alone or in admixture.
With the foregoing components, other components such as a surfactant, dissolution inhibitor, water repellency improver, and acetylene alcohol may be blended in any desired combination to formulate a positive resist composition.
Exemplary surfactants are described in JP-A 2008-111103, paragraphs [0165]-[0166]. Inclusion of a surfactant may improve or control the coating characteristics of the resist composition. When used, the surfactant is preferably added in an amount of 0.0001 to 10 parts by weight per 100 parts by weight of the base polymer. The surfactant may be used alone or in admixture.
The inclusion of a dissolution inhibitor in the positive resist composition may lead to an increased difference in dissolution rate between exposed and unexposed areas and a further improvement in resolution. The dissolution inhibitor which can be used herein is a compound having at least two phenolic hydroxy groups on the molecule, in which an average of from 0 to 100 mol % of all the hydrogen atoms on the phenolic hydroxy groups are replaced by acid labile groups or a compound having at least one carboxy group on the molecule, in which an average of 50 to 100 mol % of all the hydrogen atoms on the carboxy groups are replaced by acid labile groups, both the compounds having a molecular weight of 100 to 1,000, and preferably 150 to 800. Typical are bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid derivatives in which the hydrogen atom on the hydroxy or carboxy group is substituted by an acid labile group, as described in U.S. Pat. No. 7,771,914 (JP-A 2008-122932, paragraphs [0155]-[0178]).
When the positive resist composition contains a dissolution inhibitor, the dissolution inhibitor is preferably added in an amount of 0 to 50 parts, more preferably 5 to 40 parts by weight per 100 parts by weight of the base polymer. The dissolution inhibitor may be used alone or in admixture.
A water repellency improver may be added to the resist composition for improving the water repellency on surface of a resist film. The water repellency improver may be used in the topcoatless immersion lithography. Suitable water repellency improvers include polymers having a fluoroalkyl group and polymers having a specific structure with a 1,1,1,3,3,3-hexafluoro-2 propanol residue and are described in JP-A 2007-297590 and JP A 2008-111103, for example. The water repellency improver to be added to the resist composition should be soluble in the alkaline developer and organic solvent developer. The water repellency improver of specific structure with a 1,1,1,3,3,3-hexafluoro-2-propanol residue is well soluble in the developer. A polymer having an amino group or amine salt copolymerized as repeat units may serve as the water repellent additive and is effective for preventing evaporation of acid during PEB, thus preventing any hole pattern opening failure after development. An appropriate amount of the water repellency improver is 0 to 20 parts, more preferably 0.5 to 10 parts by weight per 100 parts by weight of the base polymer. The water repellency improver may be used alone or in admixture.
Also, an acetylene alcohol may be blended in the resist composition. Suitable acetylene alcohols are described in JP-A 2008-122932, paragraphs [0179]-[0182]. An appropriate amount of the acetylene alcohol blended is 0 to 5 parts by weight per 100 parts by weight of the base polymer. The acetylene alcohols may be used alone or in admixture.
The positive resist composition is used in the fabrication of various integrated circuits. Pattern formation using the resist composition may be performed by well-known lithography processes. The process generally involves the steps of applying the resist composition onto a substrate to form a resist film thereon, exposing the resist film to high-energy radiation, and developing the exposed resist film in a developer. If necessary, any additional steps may be added.
The positive resist composition is first applied onto a substrate on which an integrated circuit is to be formed (e.g., Si, SiO2, SiN, SiON, TIN, WSi, BPSG, SOG, or organic antireflective coating) or a substrate on which a mask circuit is to be formed (e.g., Cr, CrO, CrON, MoSi2, or SiO2) by a suitable coating technique such as spin coating, roll coating, flow coating, dipping, spraying or doctor coating. The coating is prebaked on a hot plate at a temperature of 60 to 150′C for 10 seconds to 30 minutes, preferably at 80 to 120′C for 30 seconds to 20 minutes. The resulting resist film is generally 0.01 to 2 μm thick.
The resist film is then exposed to a desired pattern of high-energy radiation such as UV deep-UV, EB. EUV of wavelength 3-15 mu, x-ray, soft x-ray, excimer laser light, γ-ray or synchrotron radiation. When UV, deep-UV, EUV, x-ray, soft x-ray, excimer laser light, γ-ray or synchrotron radiation is used as the high-energy radiation, the resist film is exposed thereto directly or through a mask having a desired pattern in a dose of preferably about 1 to 200 mJ/cm2, more preferably about 10 to 100 mJ/cm2. When EB is used as the high-energy radiation, the resist film is exposed thereto directly or through a mask having a desired pattern in a dose of preferably about 0.1 to 100 μC/cm2, more preferably about 0.5 to 50 μC/cm2. It is appreciated that the positive resist composition is suited in micropatterning using i-line of wavelength 365 mm, KrF excimer laser, ArF excimer laser, EB, EUV, x-ray, soft x-ray, γ-ray or synchrotron radiation, especially in micropatterning using EB or EUV.
After the exposure, the resist film may be baked (PEB) on a hotplate or in an oven preferably at 50 to 150° C., for 10 seconds to 30 minutes, more preferably at 60 to 120° C. for 30 seconds to 20 minutes.
After the exposure or PEB, the resist film is developed in a developer in the form of an aqueous base solution for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes by conventional techniques such as dip, puddle and spray techniques. A typical developer is a 0.1 to 10 wt %, preferably 2 to 5 wt % aqueous solution of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAR), tetrapropylammonium hydroxide (TPAH), or tetrabutylammonium hydroxide (TBAH). The resist film in the exposed area is dissolved in the developer whereas the resist film in the unexposed area is not dissolved. In this way, the desired positive pattern is formed on the substrate.
In an alternative embodiment, a negative pattern may be forayed via organic solvent development using the positive resist composition. The developer used herein is preferably selected from among 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate, and mixtures thereof.
At the end of development, the resist film is rinsed. As the rinsing liquid, a solvent which is miscible with the developer and does not dissolve the resist film is preferred. Suitable solvents include alcohols of 3 to 10 carbon atoms, ether compounds of 8 to 12 carbon atoms, alkanes, alkenes, and alkynes of 6 to 12 carbon atoms, and aromatic solvents. Specifically, suitable alcohols of 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, t-butyl alcohol, 1 pentanol, 2-pentanol, 3-pentanol, t-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl−1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol. Suitable ether compounds of 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-s-butyl ether, di-n-pentyl ether, diisopentyl ether, di-s-pentyl ether, di-t-pentyl ether, and di-n-hexyl ether. Suitable alkanes of 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Suitable alkenes of 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Suitable alkynes of 6 to 12 carbon atoms include hexyne, heptyne, and octyne. Suitable aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, t-butylbenzene and mesitylene. The solvents may be used alone or in admixture.
Rinsing is effective for minimizing the risks of resist pattern collapse and defect formation. However, rinsing is not essential. If rinsing is omitted, the amount of solvent used may be reduced.
A hole or trench pattern after development may be shrunk by the thermal flow, RELACS® or DSA process. A hole pattern is shrunk by coating a shrink agent thereto, and baking such that the shrink agent may undergo crosslinking at the resist surface as a result of the acid catalyst diffusing from the resist layer during bake, and the shrink agent may attach to the sidewall of the hole pattern. The bake is preferably at a temperature of 70 to 180° C., more preferably 80 to 170° C., for a time of 10 to 300 seconds. The extra shrink agent is stripped and the hole pattern is shrunk.
Examples of the invention are given below by way of illustration and not by way of limitation. The abbreviation “pbw” is parts by weight.
[1] Synthesis of monomers
Synthesis of Monomer M-1
In a reactor, 9.06 g of 2-(4-nitrophenyl)-2-propanol, 8.60 g of triethylamine, and 0.61 g of 4-dimethylaminopyridine were dissolved in 25 mL of acetonitrile. While the reactor was kept at an internal temperature of 40-60° C., 7.32 g of methacrylic chloride was added dropwise thereto. Stirring was continued for 19 hours at the internal temperature of 60° C. The reaction solution was cooled to which 20 mL of saturated sodium bicarbonate aqueous solution was added to quench the reaction. The end compound was extracted with a mixture of 25 mL toluene, 15 mL hexane and 15 mL ethyl acetate. This was followed by standard aqueous workup, solvent distillation, and vacuum distillation, obtaining 9.02 g of Monomer M-1 as colorless transparent oil.
Synthesis of Monomer M-2
Monomer M-2, shown below, was synthesized by the same procedure as in Synthesis Example 1-1 except that 2-(3-nitrophenyl)-2-propanol was used instead of 2-(4-nitrophenyl)-2-propanol.
Synthesis of Monomer M-3
Monomer M-3, shown below, was synthesized by the same procedure as in Synthesis Example 1-1 except that 2-(3-fluoro-4 nitrophenyl)-2-propanol was used instead of 2-(4-nitrophenyl)-2-propanol.
Synthesis of Monomer M-4
Monomer M-4, shown below, was synthesized by the same procedure as in Synthesis Example 1-1 except that Compound C-1, shown below, was used instead of 2-(4-nitrophenyl)-2-propanol.
Synthesis of Monomer M-5
Monomer M-5, shown below, was synthesized by the same procedure as in Synthesis Example 1-1 except that Compound C-2, shown below, was used instead of 2-(4 nitrophenyl)-2-propanol.
[2] Synthesis of polymers
Monomers PM-1 to PM-4, AM-1 to AM-5, FM-1 and FM-2 used in the synthesis of polymers have the structure shown below. The polymer is analyzed for composition by 13C— and 1H-NMR spectroscopy and for Mw and Mw/Mn by GPC versus polystyrene standards using tetrahydrofuran (THF) solvent.
Synthesis of Polymer P-1
A 2-L flask was charged with 14.9 g of Monomer M-1, 4.8 g of 4-hydroxystyrene, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of azobisisobutyronitrile (AIBN) as polymerization initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of isopropyl alcohol (IPA) for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-1. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-2
A 2-L flask was charged with 6.3 g of Monomer M-1, 5.1 g of Monomer AM-2, 6.0 g of 3-hydroxystyrene, and 40 g of THE solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-2. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-3
A 2-L flask was charged with 7.5 g of Monomer M-1, 4.6 g of Monomer AM-3, 6.0 g of 3-hydroxystyrene, and 40 g of THE solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-3. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-4
A 2-L flask was charged with 12.5 g of Monomer M-1, 4.2 g of 3-hydroxystyrene, 11.9 g of Monomer PM-1, and 40 g of THE solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P4. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-5
A 2-L flask was charged with 2.5 g of Monomer M-2, 5.2 g of 1-(cyclopropyl-1 yl)-1-methylethyl methacrylate, 3.5 g of 3-fluoro-4-(methylcyclohexyloxy)styrene, 4.8 g of 3-hydroxystyrene, 11.2 g of Monomer PM-3, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-5. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-6
A 2-L flask was charged with 3.2 g of Monomer M-3, 6.4 g of 1-methyl-1-cyclopentyl methacrylate, 4.2 g of 4-hydroxystyrene, 11.0 g of Monomer PM-2, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-6. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-7
A 2-L flask was charged with 3.7 g of Monomer M-1, 7.8 g of Monomer AM-1, 4.2 g of 3-hydroxystyrene, 11.0 g of Monomer PM-2, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-7. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-8
A 2-L flask was charged with 3.0 g of Monomer M-1, 6.4 g of 1-methyl-1-cyclopentyl methacrylate, 4.2 g of 4-hydroxystyrene, 9.6 g of Monomer PM-3, and 40 g of THF solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-8. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-9
A 2-L flask was charged with 3.0 g of Monomer M-1, 5.9 g of tert-amyl methacrylate, 4.2 g of 4-hydroxystyrene, 11.9 g of Monomer PM-4, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-9. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-10
A 2-L flask was charged with 14.9 g of Monomer M-1, 4.2 g of 4-hydroxystyrene, 4.0 g of Monomer PM-2, and 40 g of THE solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-10. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-11
A 2-L flask was charged with 14.9 g of Monomer M-1, 3.2 g of 4-hydroxystyrene, 3.6 g of Monomer FM-1, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-11. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-12
A 2-L flask was charged with 14.9 g of Monomer M-1, 3.6 g of 4-hydroxystyrene, 3.3 g of Monomer FM-2, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-12. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-13
A 2-L flask was charged with 7.5 g of Monomer M-1, 3.6 g of Monomer AM-4, 6.0 g of 3-hydroxystyrene, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-13. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-14
A 2-L flask was charged with 7.5 g of Monomer M-1, 3.6 g of Monomer AM-5, 6.0 g of 4-hydroxystyrene, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C. and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-14. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-15
A 2-L flask was charged with 5.0 g of Monomer M-1, 4.5 g of Monomer AM-1, 10.7 g of 2-hydroxyphenyl methacrylate, and 40 g of THF solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-15. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-16
A 2-L flask was charged with 5.0 g of Monomer M-1, 6.7 g of Monomer AM-1, 8.9 g of 3-hydroxyphenyl methacrylate, and 40 g of THF solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-16 The polymer war analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-17
A 2-L flask was charged with 7.5 g of Monomer M-1, 7.5 g of Monomer AM-1, 7.1 g of 4-hydroxyphenyl methacrylate, and 40 g of THF solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-17. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-18
A 2-L flask was charged with 16.5 g of Monomer M-4, 4.8 g of 4-hydroxystyrene, and 40 g of THF solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-18. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Polymer P-19
A 2-L flask was charged with 17.5 g of Monomer M-5, 4.8 g of 4-hydroxystyrene, and 40 g of THE solvent. The reactor was cooled at −70° C., in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN initiator was added. The reactor was heated at 60° C., and held at the temperature for 15 hours for reaction. The reaction solution was poured into 1 L of IPA for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., obtaining Polymer P-19. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Comparative Polymer cP-1
Comparative Polymer cP-1 was synthesized by the same procedure as in Synthesis Example 2-1 except that 1-methyl-1-cyclopentyl methacrylate was used instead of Monomer M-1. The polymer was analyzed by NMR spectroscopy and GPC.
Synthesis of Comparative Polymer cP-2
Comparative Polymer cP-2 was synthesized by the same procedure as in Synthesis Example 2-6 aside from omitting Monomer M-3. The polymer was analyzed by NMR spectroscopy and GPC.
Positive resist compositions were prepared by dissolving the selected components in a solvent in accordance with the recipe shown in Table 1, and filtering through a filter having a pore size of 0.2 μm. The solvent contained 50 ppm of surfactant PolyFox PF-636 (Omnova Solutions Inc.).
The components in Table 1 are as identified below.
PGMEA (propylene glycol monomethyl ether acetate)
DAA (diacetone alcohol)
EL (ethyl lactate)
(2) EUV lithography test
Each of the positive resist compositions in Table 1 was spin coated on a silicon substrate having a 20 nm coating of silicon-containing spin-on hard mask SHB-A940 (Shin-Etsu Chemical Co., Ltd., silicon content 43 wt %) and prebaked on a hotplate at 105° C. for 60 seconds to form a resist film of 60 nm thick Using an EUV scanner NXE3300 (ASML, NA 0.33, v 0.9/0.6, quadrupole illumination), the resist film was exposed to EUV through a mask bearing a hole pattern having a pitch (on-wafer size) of 46 nm+20% bias. The resist film was baked (PEB) on a hotplate at the temperature shown in Table 1 for 60 seconds and developed in a 2.38 wt % TMAH aqueous solution for 30 seconds to form a hole pattern having a size of 23 nm.
The resist pattern was observed under CD-SEM (CG-5000, Hitachi High-Technologies Corp.). The exposure dose that provides a hole pattern of 23 nm size is reported as sensitivity. The size of 50 holes was measured, from which a 3-fold value (3σ) of standard deviation (σ) was computed and reported as CDU.
The resist composition is shown in Table 1 together with the sensitivity and CDU of EUV lithography.
It is demonstrated in Table 1 that positive resist compositions comprising a base polymer comprising repeat units (a) having a carboxy group whose hydrogen is substituted by a nitrobenzene ring-containing tertiary hydrocarbyl group have a high sensitivity and form patterns with improved CDU.
Japanese Patent Application No. 2021-090241 is incorporated herein by reference.
Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-090241 | May 2021 | JP | national |
