Resist Composition and Pattern Forming Method

Abstract

To provide a resist composition that exhibits superior sensitivity and resolution in photo lithography using high-energy radiation, and a patterning process using the resist composition.SOLUTION: A resist composition comprises a hypervalent iodine compound having at least two acyloxy groups, a carboxylic acid compound, and a solvent.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] With the expansion of the IoT market, further requirements for higher integration, higher speed, and lower power consumption of LSIs have emerged, and the miniaturization of pattern rules has been rapidly progressing. In particular, logic devices are leading the way in miniaturization. As the most advanced miniaturization technology, mass production of 10 nm node devices by double patterning, triple patterning, and quadruple patterning of ArF immersion lithography has been carried out, and further studies on 7 nm node devices using extreme ultraviolet (EUV) lithography with a next-generation wavelength of 13.5 nm are underway.

[0003] With the progress of miniaturization, image blur due to acid diffusion has become a problem (Non-Patent Document 1). In order to ensure the resolution of fine patterns with a dimensional size of 45 nm or less, it has been proposed that not only the improvement of the dissolution contrast proposed conventionally but also the control of acid diffusion is important (Non-Patent Document 2). However, since the chemically amplified resist composition increases the sensitivity and contrast by acid diffusion, if the post-exposure bake (PEB) temperature is lowered or the PEB time is shortened to suppress acid diffusion to the limit, the sensitivity and contrast will be significantly reduced.

[0004] Adding an acid generator that generates a bulky acid to suppress acid diffusion is effective. Therefore, it has been proposed to copolymerize an acid generator of an onium salt having a polymerizable olefin with a polymer. However, in the pattern formation of a resist film with a dimensional size of 16 nm or less, it is considered that pattern formation cannot be achieved with a chemically amplified resist composition from the viewpoint of acid diffusion, and the development of a non-chemically amplified resist composition is desired.

[0005] As a material for a non-chemically amplified resist composition, polymethyl methacrylate (PMMA) can be mentioned. PMMA is a positive resist material in which the main chain is cleaved by EUV irradiation and the solubility in an organic solvent developer is improved by a decrease in molecular weight.

[0006] Hydrogen silsesquioxane (HSQ) is a negative resist material that becomes insoluble in an alkaline developer by crosslinking due to the condensation reaction of silanol generated by EUV irradiation. Also, chlorine-substituted calixarene also functions as a negative resist material. These negative resist materials have a small molecular size before crosslinking and no blurring due to acid diffusion, so they have a small edge roughness and very high resolution, and are used as pattern transfer materials for showing the resolution limit of exposure apparatuses. However, these materials have insufficient sensitivity and further improvement is required.

[0007] One of the factors that makes it difficult to develop materials for EUV lithography is the small number of photons in EUV exposure. The energy of EUV is much higher than that of ArF excimer laser light, and the number of photons in EUV exposure is 1 / 14 of that in ArF exposure. Furthermore, the size of the pattern formed by EUV exposure is less than half of that in ArF exposure. For this reason, EUV exposure is easily affected by variations in the number of photons. The variation in the number of photons in the extreme ultraviolet radiation region is shot noise of a physical phenomenon and cannot be eliminated. Therefore, so-called Stochastics has attracted attention. Although it is impossible to eliminate the influence of shot noise, discussions are being held on how to reduce this influence. The influence of shot noise not only increases the dimension uniformity (CDU) and line width roughness (LWR), but also a phenomenon in which holes are blocked with a probability of one in several million has been observed. When a hole is blocked, the current conduction becomes poor and the transistor does not operate, which has an adverse effect on the performance of the entire device. Considering the application of a resist with practical sensitivity, resist compositions mainly composed of PMMA or HSQ are greatly affected by Stochastics and have not been able to obtain the desired resolution performance.

[0008] As a method for reducing the influence of shot noise on the resist side, the introduction of elements with high EUV absorption has attracted attention. Patent Document 1 proposes a chemically amplified resist composition containing iodine atoms with high EUV light absorption. However, as described above, chemically amplified resists cannot achieve excellent resolution performance in EUV lithography where the dimensional size will be further miniaturized in the future.

[0009] Patent Document 2 proposes a negative resist composition using a tin compound. Since this mainly contains tin elements with high EUV light absorption, Stochastics is improved and high sensitivity and high resolution can be achieved. However, so-called such metal resists have many problems such as insufficient solubility in resist solvents, storage stability, and defects due to residues after etching. Furthermore, since metal resists are mainly negative types in which the exposed part becomes a metal oxide and becomes insoluble in the developer, when applied to the patterning of contact holes, an additional inversion process step is required, and there are also concerns in terms of cost.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0011]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention has been made in view of the above circumstances, and provides a resist composition excellent in sensitivity and resolution, and a pattern forming method using the resist composition, in photolithography using high-energy rays, particularly electron beam (EB) lithography and EUV lithography.

Means for Solving the Problems

[0013] As a result of intensive studies to achieve the above object, the present inventors have found that a resist composition mainly composed of a hypervalent iodine compound having at least two acyloxy groups and a carboxylic acid compound has extremely high sensitivity and gives a resist film showing excellent resolution, and is extremely effective for precise microfabrication, and thus the present invention has been completed.

[0014] That is, the present invention provides the following resist composition and pattern forming method. 1. A resist composition containing a hypervalent iodine compound having at least two acyloxy groups, a carboxylic acid compound, and a solvent. 2. The resist composition of 1, wherein the hypervalent iodine compound is represented by the following formula (1).

Chemical formula

[0015] The resist composition of the present invention is extremely useful for forming fine patterns, achieving both high sensitivity and high resolution, particularly in EB lithography and EUV lithography.

Embodiments for Carrying Out the Invention

[0016] [Resist Composition] The resist composition of the present invention contains a hypervalent iodine compound having at least two acyloxy groups and a carboxylic acid compound as main components.

[0017] [Hypervalent Iodine Compound] The hypervalent iodine compound is a general term for iodine compounds having valence electrons formally exceeding the octet rule. The hypervalent iodine compound used in the present invention is not particularly limited as long as it has at least two acyloxy groups, and examples include three-coordinate iodine compounds with an oxidation number of +3 and five-coordinate iodine compounds with an oxidation number of +5.

[0018] As the hypervalent iodine compound, a three-coordinate hypervalent iodine compound represented by the following formula (1) is preferable.

Chemical formula

[0019] In formula (1), n is an integer from 0 to 5.

[0020] In formula (1), R 1 and R 2 are each independently a halogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hetero atom. Also, R 1 and R 2may be bonded to each other to form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The hydrocarbyl group having 1 to 10 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, etc.; alkenyl groups such as vinyl group, allyl group, etc.; aryl groups having 6 to 10 carbon atoms such as phenyl group, naphthyl group, etc.; groups obtained by combining these, etc. Further, a part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH 2 - constituting the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), etc. R 1 and R 2 are preferably hydrocarbyl groups having 1 to 4 carbon atoms.

[0021] In formula (1), R 3 is a halogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. When n is 2 to 5, each R 3They may be the same as or different from each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The hydrocarbyl group having 1 to 40 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, an adamantyl group, an adamantylmethyl group, etc.; aryl groups having 6 to 40 carbon atoms such as a phenyl group, a naphthyl group, an anthracenyl group, etc. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH 2 - constituting the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), etc.

[0022] Specific examples of the hypervalent iodine compound represented by the formula (1) include, but are not limited to, those shown below.

Chemical formula

[0023]

Chemical formula

[0024] [Chemistry]

[0025] [Chemistry]

[0026] [Chemistry]

[0027] [Chemistry]

[0028] [Carboxylic acid compound] The carboxylic acid compounds used in the present invention can generally be any carboxylic acid compounds defined in organic chemistry, but those represented by the following formula (2) are preferred. [Chemistry]

[0029] In formula (2), m is an integer from 1 to 4. R 11 is an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms. When m is 2, R 11 may be an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group or a sulfonyl group. Also, some or all of the hydrogen atoms of the m-valent hydrocarbon group or m-valent heterocyclic group may be substituted with a group containing a hetero atom, and -CH 2 - of the m-valent hydrocarbon group may be substituted with a group containing a hetero atom. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, and -CH 2- may be partially substituted with a group containing a heteroatom. When m is 2 to 4, each R 12 may be the same as or different from each other.

[0030] R 11 The m-valent hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. The m-valent hydrocarbon group is a group obtained by removing m hydrogen atoms from a hydrocarbon. Examples of the hydrocarbon include alkanes having 1 to 40 carbon atoms, alkenes having 2 to 40 carbon atoms, alkynes having 2 to 40 carbon atoms, cyclo-saturated hydrocarbons having 3 to 40 carbon atoms, cyclo-unsaturated hydrocarbons having 3 to 40 carbon atoms, and aromatic hydrocarbons having 6 to 40 carbon atoms.

[0031] Examples of the alkanes having 1 to 40 carbon atoms include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, and their structural isomers.

[0032] The carbon number 2 Examples of the alkenes having ~40 carbon atoms include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and their structural isomers.

[0033] The carbon number 2 Examples of the alkynes having ~40 carbon atoms include acetylene, propyne, butyne, pentyne, hexyne, heptyne, octyne, nonyne, decyne, and their structural isomers.

[0034] Examples of the cyclo-saturated hydrocarbons having 3 to 40 carbon atoms include cyclopropane, cyclobutane, cyclohexane, cycloheptane, cyclooctane, adamantane, norbornane, and the like.

[0035] Examples of the cyclo-unsaturated hydrocarbons having 3 to 40 carbon atoms include cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, norbornene, and the like.

[0036] Examples of the aromatic hydrocarbon having 6 to 40 carbon atoms include benzene, naphthalene, biphenyl and the like.

[0037] R 11 The m-valent heterocyclic group represented by R is a group obtained by removing m hydrogen atoms from a heterocyclic compound. Examples of the heterocyclic compound include furan, pyridine, pyrazole, thiazolidine and the like.

[0038] A part or all of the hydrogen atoms of the m-valent hydrocarbon group or m-valent heterocyclic group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and as a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. Further, in the m-valent hydrocarbon group, a part of -CH 2 - constituting it may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-) and the like.

[0039] R 12 The hydrocarbylene group represented by R may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl Base etc. having 1 to 1 10 carbon atoms of an alkanediyl group; a cyclopentanediyl group, a cyclohexanediyl group, a norbornanediyl group, an adamantanediyl group and the like having 3 to 1 10 carbon atoms of a cyclic saturated hydrocarbylene group; a vinylene group, a propene-1,3-diyl group and the like having 2 to 1An unsaturated aliphatic hydrocarbylene group of 0; an arylene group of 6 to 1 0, such as a phenylene group or a naphthylene group; groups obtained by combining these, etc. Further, part or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and -CH 2 - of the hydrocarbylene group may be partially substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, etc.

[0040] Among the carboxylic acid compounds represented by formula (2), those in which m is an integer of 2 to 4 are preferred. In this case, when mixed with the hypervalent iodine compound, it is easy to form a high-molecular-weight and strong resist film, which is preferred from the viewpoints of etching resistance and developer resistance.

[0041] Examples of the carboxylic acid compound include, but are not limited to, those shown below.

Chemical formula

[0042]

Chemical formula

[0043]

Chemical formula

[0044] In the resist composition of the present invention, the content ratio of the hypervalent iodine compound and the carboxylic acid compound is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and still more preferably 30:70 to 70:30 in terms of molar ratio.

[0045] [Organic solvent] The resist composition of the present invention contains an organic solvent. The solvent is not particularly limited as long as it can dissolve the hypervalent iodine compound and the carboxylic acid compound used in the present invention and can form a film. Examples of such organic solvents include ketones such as cyclohexanone, methyl-2-n-pentyl ketone, and methyl isoamyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, and 4-methyl-2-pentanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; carboxylic acids such as formic acid, acetic acid, and propionic acid; lactones such as γ-butyrolactone; and mixed solvents thereof.

[0046] The content of the organic solvent is preferably an amount such that the solid content concentration in the resist composition is 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, and still more preferably 0.1 to 10% by mass. In the present invention, the solid content is a general term for components other than the solvent among all components of the resist composition.

[0047] [Other components] The resist composition of the present invention may further contain a surfactant as other components. As the surfactant, a fluorine-based and / or silicon-based surfactant is preferable. Examples of such surfactants include the surfactants described in paragraph

[0276] of US Patent Application Publication No. 2008 / 0248425. Further, in the present invention, surfactants other than the fluorine-based and / or silicon-based surfactants described in paragraph

[0280] of US Patent Application Publication No. 2008 / 0248425 can also be used. When the resist composition of the present invention contains the surfactant, its content is preferably 0.0001 to 2% by mass in the total solid content. The surfactant may be used alone or in combination of two or more.

[0048] The resist composition of the present invention may further contain a radical scavenger as other components. By adding a radical scavenger, the photoreaction during photolithography can be controlled and the sensitivity can be adjusted.

[0049] Examples of the radical scavenger include hindered phenols, quinones, hindered amines, thiol compounds, etc. Specifically, examples of hindered phenols include dibutylhydroxytoluene (BHT), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), etc. Examples of quinones include 4-methoxyphenol (methoquinone), hydroquinone, etc. Examples of hindered amines include 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpiperidine-N-oxyl radical, etc. Examples of thiols include dodecanethiol, hexadecanethiol, etc. When the resist composition of the present invention contains the radical scavenger, its content is preferably 0.01 to 10% by mass in the total solid content. The radical scavenger may be used alone or in combination of two or more.

[0050] The resist composition of the present invention contains a hypervalent iodine compound and a carboxylic acid compound as main components, and does not contain a base polymer with an acid-labile group or a photoacid generator as contained in conventional chemically amplified resist compositions. However, in the resist composition of the present invention, particularly upon exposure by EB and EUV exposure, the exposed portion becomes soluble in the developer, and a positive pattern can be formed. Although the mechanism thereof is not completely clear, it is presumed as follows, for example.

[0051] The hypervalent iodine compound used in the present invention is a three-coordinate compound in which an aryl group and two carboxylate ligands are bonded as represented by formula (1). It is considered that such a three-coordinate iodine compound causes an exchange of carboxylate ligands by an equilibrium reaction when mixed with a carboxylic acid compound. At this time, if the original carboxylate ligand can be removed by some method, a hypervalent iodine compound having a new ligand is generated. For example, if iodobenzene diacetate, which is relatively easily available as a hypervalent iodine compound, is mixed with a carboxylic acid compound having a large molecular weight and the generated low-boiling acetic acid is removed, the ligand exchange is completed. If the ligand has a sufficiently large molecular weight, it is possible to form a strong resist film. Particularly when the carboxylic acid compound has a plurality of carboxy groups, for example, when a dicarboxylic acid compound is used, it is considered that a high molecular weight polymer having a polyester structure having a hypervalent iodine compound can be formed, ensuring film-forming properties and obtaining sufficient developer resistance.

[0052] A conjugate of such a hypervalent iodine compound and a carboxylic acid compound is generated during film formation preparation. That is, by removing the low molecular weight carboxylic acid component generated during film formation and the subsequent baking step, the ligand exchange reaction is completed and a resist film is formed.

[0053] The resist film obtained from the resist composition of the present invention has extremely low solubility in organic solvents. This is presumably due to the iodine compound with a large polarization. However, it is presumed that by being decomposed by light, it becomes soluble in organic solvents and functions as a positive resist composition. Alternatively, if the photolysis product is a low molecular weight component, it is also possible to volatilize and remove the exposed portion, that is, to perform patterning without using a developer.

[0054] From the above speculation, the resist composition of the present invention Non-chemically amplified can be said to be a resist composition. Therefore, according to the resist composition of the present invention, blurring of the image due to acid diffusion, which is seen in conventional chemically amplified resist compositions (compositions containing a base polymer and a photoacid generator), does not occur, and it becomes possible to resolve a fine pattern.

[0055] The resist composition of the present invention is extremely effective particularly in EUV lithography. This is due to having iodine atoms with high absorption ability for EUV light. That is, shot noise is reduced, and higher resolution and lower LWR can be achieved.

[0056] As an EUV resist composition capable of forming a fine pattern, a metal resist mainly composed of a metal tin compound having a high EUV light absorption ability similar to that of iodine atoms has been reported (for example, Patent Document 2). However, as described above, such a metal resist has many problems such as insufficient solubility in a solvent, storage stability, and defects due to residues after etching containing a metal element. On the other hand, since the resist composition of the present invention does not use a metal element, it is more advantageous than the metal resist in terms of defects and there is no problem with solubility in a solvent. Furthermore, by using the resist composition of the present invention, a positive pattern is formed by non-development or organic solvent development. Therefore, for example, in the contact hole forming process, the inversion process step performed by negative development becomes unnecessary. From these points, it can be said that the resist composition of the present invention is more useful than the metal resist.

[0057] Patent Documents 3 and 4 describe a resist composition containing a hypervalent iodine compound as an additive, and a resist composition in which a hypervalent iodine compound is incorporated into the polymer skeleton of a base polymer. However, as the characteristics of the resist compositions described in these patent documents, there is only a description that line edge roughness can be improved, and there is no mention at all of the possibility that the hypervalent iodine compound may be photodecomposed or the possibility of functioning as a non-chemically amplified resist. Furthermore, the hypervalent iodine compound is not the main component. Therefore, it is considered that these patent documents do not lead to the idea of a material that can reduce shot noise in EUV lithography and can form fine patterns as a non-chemically amplified resist as in the present invention. That is, it can be said that the present invention clearly provides a novel resist composition and a pattern forming method.

[0058] [Pattern Forming Method] When the resist composition of the present invention is used in various integrated circuit manufacturing processes, known lithography techniques can be applied. For example, as a pattern forming method, there is a method including a step of forming a resist film on a substrate using the above-described resist composition, a step of exposing the resist film with high energy rays, and a step of developing the exposed resist film using a developer as necessary.

[0059] First, the resist composition of the present invention is applied onto a substrate for integrated circuit manufacturing (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflection film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc. so that the coating film thickness becomes 0.01 to 2 μm. This is prebaked (PB) on a hot plate, preferably at 60 to 200°C for 10 seconds to 30 minutes, more preferably at 80 to 180°C for 30 seconds to 20 minutes, to form a resist film.

[0060] Next, the resist film is exposed using high-energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. When using ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. as the high-energy rays, the exposure dose is preferably 1 to 300 mJ / cm 2 level, more preferably 10 to 200 mJ / cm 2 level and irradiated. When using EB as the high-energy ray, the exposure dose is preferably 0.1 to 2000 μC / cm 2 level, more preferably 0.5 to 1500 μC / cm 2 level and drawn using a mask for forming a target pattern directly or. The resist composition of the present invention is particularly suitable for fine patterning by EB or EUV among high-energy rays.

[0061] The resist composition of the present invention may be subjected to PEB after exposure if necessary. In that case, it is preferably carried out under the conditions of 30 to 120 °C for 10 seconds to 30 minutes, more preferably 60 to 100 °C for 30 seconds to 20 minutes, on a hot plate or in an oven after exposure.

[0062] After exposure or PEB, development is carried out using a developer as necessary to form a pattern. In the present invention, the exposed portion can be solubilized by organic solvent development to obtain a positive pattern. As the developer used at this time, 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, isopropyl alcohol, n-butanol, n-pentanol, 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, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, 2-propanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, 4-methyl-2-pentanol, etc. can be mentioned. These organic solvents may be used alone or in combination of two or more.

[0063] After development, rinsing is carried out as necessary. As the rinsing solution, a solvent that is miscible with the developer and does not dissolve the resist film is preferred. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms are preferably used.

[0064] By performing rinsing, it is possible to reduce the collapse of the resist pattern and the occurrence of defects. Also, rinsing is not necessarily essential, and the amount of solvent used can be reduced by not performing rinsing.

Example

[0065] Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[0066] [1] Preparation of resist composition [Examples 1-1 to 1-15, Comparative Examples 1-1 to 1-3] An iodine-rich compound and a carboxylic acid compound were dissolved in a solvent with the compositions shown in Table 1 below, and the resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist compositions (R-01 to R-15). Also, a base polymer, a photoacid generator, a sensitivity adjuster, a solvent, and 0.01% by mass of a surfactant (PF-636, manufactured by Omnova) were mixed with the compositions shown in Table 2 below, and the resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist compositions for comparative examples (CR-01 to CR-03).

[0067]

Table 1

[0068]

Table 2

[0069] In Table 1, the iodine-rich compounds (I-1 to I-3), the carboxylic acid compounds (CA-1 to CA-10), and the solvents are as follows.

Chemical formula

[0070]

Chemical formula

[0071] · Solvent: PGMEA (propylene glycol monomethyl ether acetate) AcOH (acetic acid) GBL (γ-butyrolactone)

[0072] In Table 2, the base polymer (P-1), photoacid generators (PAG-1, PAG-2), and sensitivity adjusters (Q-1, Q-2) are as follows. [Chemical formula] Mw = 8755 (polystyrene equivalent), Mw / Mn = 1.94

[0073] [Chemical formula]

[0074] [Chemical formula]

[0075] [2] EUV Lithography Evaluation (Line and Space Pattern) [Examples 2-1 to 2-15, Comparative Examples 2-1 to 2-3] Each resist composition (R-01 to R-15, CR-01 to CR-03) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed to a film thickness of 20 nm, and prebaked (PB) at the temperature shown in Table 3 for 60 seconds using a hot plate to prepare a resist film with a film thickness of 40 nm. After exposure to a 36 nm line and space (LS) 1:1 pattern using an EUV scanner NXE3400 (NA 0.33, σ 0.9, 90-degree dipole illumination) manufactured by ASML, post-exposure bake (PEB) was performed on a hot plate at the temperature shown in Table 3 for 60 seconds, and then development was carried out for 30 seconds with the developer shown in Table 3 to form an LS pattern with a space width of 18 nm and a pitch of 36 nm. The following evaluations were performed on the obtained resist patterns. The results are shown in Table 3.

[0076] [Sensitivity evaluation] The LS pattern was observed using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the optimum exposure dose Eop (mJ / cm 2 ) at which an LS pattern with a space width of 18 nm and a pitch of 36 nm was obtained was determined.

[0077] [LWR evaluation] The LS pattern obtained by irradiating with the optimum exposure dose was measured for the dimensions at 10 locations in the longitudinal direction of the space width using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the three-fold value (3σ) of the standard deviation (σ) was determined as the LWR from the results. The smaller this value, the smaller the roughness and the more uniform the pattern with a space width can be obtained.

[0078] [Limit resolution evaluation] From the optimum exposure dose at which the LS pattern was formed, the limit line width (nm) at which the pattern resolves when the exposure dose was gradually increased to form the pattern was determined using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and this was defined as the limit resolution (nm). The smaller this value, the better the limit resolution and the more finely detailed pattern can be formed.

[0079]

Table 3

[0080] Developer: nBA (butyl acetate) TMAH (2.38 mass% aqueous solution of tetramethylammonium hydroxide)

[0081] From the results shown in Table 3, it was found that the resist composition of the present invention is excellent in sensitivity, LWR, and resolution in the formation of an LS pattern by EUV exposure.

[0082] [3] EUV lithography evaluation (contact hole pattern) [Examples 3-1 to 3-15, Comparative Examples 3-1 to 3-3] Each resist composition (R-01 to R-15, CR-01 to CR-03) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd. was formed with a film thickness of 20 nm, and PB was performed for 60 seconds at the temperature described in Table 4 using a hot plate to produce a resist film with a film thickness of 50 nm. Next, the resist film was exposed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask of a hole pattern with a wafer size of pitch 64 nm and +20% bias) manufactured by ASML, PEB was performed for 60 seconds at the temperature described in Table 4 on a hot plate, and development was performed for 30 seconds with the developer described in Table 4 to obtain a hole pattern with a dimension of 32 nm. The following evaluations were performed on the obtained resist pattern. The results are shown in Table 4.

[0083] [Sensitivity Evaluation] The contact hole pattern was observed using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and the optimum exposure dose Eop (mJ / cm 2 ) at which a hole pattern with a dimension of 22 nm was obtained was determined.

[0084] [CDU Evaluation] The dimensions of 50 hole patterns obtained by irradiating with the optimum exposure dose were measured, and three times the standard deviation (σ) calculated from the results was defined as CDU. The smaller this value is, the more uniform the hole diameter pattern can be obtained.

[0085] [Limit Resolution Evaluation] From the optimum exposure dose at which the hole pattern was formed, the limit hole diameter (nm) at which resolution occurred when forming the hole pattern by gradually decreasing the exposure dose was determined using a length-measuring SEM (CG-6300) manufactured by Hitachi High-Tech Corporation, and this was defined as the limit resolution (nm). The smaller this value is, the better the limit resolution, indicating that a pattern with a finer hole diameter can be formed.

[0086]

Table 4

[0087] From the results shown in Table 4, it was found that the resist composition of the present invention is excellent in sensitivity, CDU, and resolution in the formation of contact hole patterns by EUV exposure.

Claims

Claim 1: A non-chemically amplified resist composition comprising a hypervalent iodine compound having at least two acyloxy groups represented by the following formula (1), a carboxylic acid compound represented by the following formula (2), and a solvent, and not containing a base polymer and a photoacid generator. 【Chemical 1】 (In the formula, n is an integer from 0 to 5.) R 1 and R 2 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a halogen atom or a hetero atom. R 3 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a halogen atom or a hetero atom. When n is 2 to 5, each R 3 may be the same as or different from each other. ) [[Chemical Formula 2]] (In the formula, m is an integer from 2 to 4.) When m is 3 or 4, R 11 is an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms. When m is 2, R 11 is an ether bond, a carbonyl group, an azo group, a thioether bond, a carbonate bond, a carbamate bond, a sulfinyl group, a sulfonyl group, an m-valent hydrocarbon group having 1 to 40 carbon atoms or an m-valent heterocyclic group having 2 to 40 carbon atoms. Further, some or all of the hydrogen atoms of the m-valent hydrocarbon group or m-valent heterocyclic group may be substituted with a group containing a hetero atom, and a part of -CH 2 - of the m-valent hydrocarbon group may be substituted with a group containing a hetero atom. The m-valent hydrocarbon group is a group obtained by eliminating m hydrogen atoms from an alkane having 1 to 40 carbon atoms, an alkene having 2 to 40 carbon atoms, an alkyne having 2 to 40 carbon atoms, a cyclic saturated hydrocarbon having 3 to 40 carbon atoms, a cyclic unsaturated hydrocarbon having 3 to 40 carbon atoms, or an aromatic hydrocarbon having 6 to 40 carbon atoms, and the m-valent heterocyclic group is a group obtained by eliminating m hydrogen atoms from a heterocyclic compound. R 12 is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and part or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom, and -CH 2 - of the hydrocarbylene group may be substituted with a group containing a hetero atom. When m is 2 to 4, each R 12 may be the same as or different from each other. ) Claim 2: The non-chemically amplified resist composition according to Claim 1, wherein R1 and R2 are hydrocarbyl groups having 1 to 4 carbon atoms. Claim 3: The non-chemically amplified resist composition according to Claim 1, wherein the hypervalent iodine compound is represented by any of the following formulas. 【Chemical Formula 3】 【Chemical 4】 【Chemical Formula 5】 [Chemical Formula 6] 【Chemical Formula 7】 【Chemical 8】 Claim 4: The non-chemically amplified resist composition according to Claim 1, wherein the carboxylic acid compound is represented by any of the following formulas. 【Chemical Formula 9】 【Chemical 10】 【Chemical Formula 11】 Claim 5: A pattern forming method comprising a step of forming a resist film on a substrate using the non-chemically amplified resist composition according to any one of Claims 1 to 4, a step of exposing the resist film to high-energy rays, and a step of developing the exposed resist film using a developer. Claim 6: The pattern forming method according to Claim 5, wherein the developer is an organic solvent. Claim 7: The pattern forming method according to Claim 5, wherein the high-energy rays are electron beams or extreme ultraviolet rays.

Images