Resist topcoat compositions, and methods of forming patterns using the composition

Abstract

To provide a resist topcoat composition capable of reducing pattern variation by preventing pattern degradation, and a method of forming patterns using the composition.SOLUTION: The present invention relates to a resist topcoat composition and a method of forming patterns using the resist topcoat composition, the resist topcoat composition including a copolymer including a first structural unit represented by a chemical formula M-1, a second structural unit represented by a chemical formula M-2, and a third structural unit represented by at least one of a chemical formula M-3A, a chemical formula M-3B, and a chemical formula M-3C; and a solvent, wherein the copolymer has an OHV (OH value) of 5 mgKOH / g to 100 mgKOH / g. Details of the chemical formulae are as described in the specification.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This description relates to a composition for a resist upper layer film and a pattern forming method using the same.

Background Art

[0002] Recently, the semiconductor industry has been developing towards ultrafine technology having patterns with sizes from several hundred nanometers to several to several tens of nanometers. In order to realize such ultrafine technology, an effective photolithography process is essential.

[0003] A typical photolithography process includes forming a material layer on a semiconductor substrate, coating a photoresist layer thereon, exposing and developing to form a photoresist pattern, and then etching the material layer using the photoresist pattern as a mask.

[0004] As the technology of the photolithography process develops, the pattern integration density is increasing, and materials and technologies for solving various problems occurring in this process are required.

[0005] In particular, when irradiating EUV to a photoresist, photo shot noise in which regions where light is randomly irradiated more or less due to large energy per photon occur, or pattern roughness (LER: Line Edge Roughness, LWR: Line Width Roughness) or pattern variation deterioration such as IPU occurs due to the EUV absorption difference between the upper and lower parts of the photoresist. It is known that the development of technologies for improving this is required.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Provided is a composition for a resist upper layer film that can prevent pattern degradation and reduce pattern variation.

[0007] Another embodiment provides a pattern formation method using the composition for a resist upper layer film.

Means for Solving the Problems

[0008] One embodiment includes a copolymer containing a first structural unit represented by the following chemical formula M-1, a second structural unit represented by the following chemical formula M-2, and a third structural unit represented by at least one of the following chemical formulas M-3A, M-3B, and M-3C; and a solvent, The copolymer has an OHV (OH value) of 5 to 100 mgKOH / g, and provides a composition for a resist upper layer film.

Chemical Formula

Chemical formula

[0009] Another embodiment provides a patterning method including the steps of coating a photoresist composition on a substrate and heating to form a photoresist film, coating the above-mentioned composition for the resist upper layer film on the photoresist film and heating to form an upper layer film, and exposing and developing the upper layer film and the photoresist film to form a resist pattern.

Advantages of the Invention

[0010] The composition for a resist upper layer film according to an embodiment can introduce a structural unit having a functional group capable of reacting with an acid excessively activated at the upper part of a photoresist when exposed to EUV, remove the excessive acid, prevent pattern roughness (LER, LWR) or pattern variation deterioration such as IPU due to the EUV absorption difference between the upper and lower parts of the photoresist, thereby improving the variation, and can be advantageously used for forming a fine pattern of a photoresist by significantly improving the IPU of a pillar pattern.

Brief Description of the Drawings

[0011]

Figure 1

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention belongs can easily implement them. However, the present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0013] In the drawings, the thickness is enlarged to clearly show a plurality of layers and regions, and the same reference numerals are given to similar parts throughout the specification. When a part such as a layer, a film, a region, a plate, etc. is “above” another part, this includes not only the case where it is “directly above” the other part but also the case where there are other parts in between. Conversely, when a part is “directly above” another part, it means that there are no other parts in between.

[0014] Unless otherwise defined herein, "substituted" means that a hydrogen atom in a compound is replaced by a substituent selected from a halogen atom (F, Br, Cl, or I), a hydroxy group, a thiol group, a nitro group, a cyano group, an amino group, a substituted or unsubstituted C1-C30 amine group, an azide group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group and its salts, a sulfonic acid group and its salts, a phosphoric acid and its salts, a vinyl group, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C6-C30 aryl group, a C7-C30 arylalkyl group, a C6-C30 allyl group, a C1-C30 alkoxy group, a C1-C30 sulfide group, a C1-C20 heteroalkyl group, a C3-C20 heteroarylalkyl group, a C3-C30 cycloalkyl group, a C3-C15 cycloalkenyl group, a C6-C15 cycloalkynyl group, a C3-30 heterocycloalkyl group, and combinations thereof.

[0015] As used herein, the term "alkyl group" means a straight-chain or branched aliphatic hydrocarbon group, unless otherwise defined. The alkyl group can be a "saturated alkyl group" that does not contain any double or triple bonds.

[0016] The alkyl group can be a C1-C20 alkyl group. More specifically, the alkyl group can be a C1-C10 alkyl group or a C1-C6 alkyl group. For example, a C1-C5 alkyl group means one containing 1 to 5 carbon atoms in the alkyl chain and is selected from the group consisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, and tert-butyl.

[0017] Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, and the like.

[0018] In the chemical formulas described in this specification, t-Bu means a tert-butyl group.

[0019] In this description, the "cycloalkyl group" means a monovalent cyclic aliphatic hydrocarbon group unless otherwise defined.

[0020] The cycloalkyl group means a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc.

[0021] The cycloalkyl group can be a C3-C10 cycloalkyl group, for example, a C3-C8 cycloalkyl group, a C3-C7 cycloalkyl group, or a C3-C6 cycloalkyl group. For example, the cycloalkyl group can be a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, but is not limited thereto.

[0022] In this description, the "alkenyl group" means a linear or branched aliphatic hydrocarbon group and an aliphatic unsaturated alkenyl group containing one or more double bonds unless otherwise defined.

[0023] In this description, the "alkynyl group" means a linear or branched aliphatic hydrocarbon group and an aliphatic unsaturated alkynyl group containing one or more triple bonds unless otherwise defined.

[0024] In this description, the "aryl group" means a substituent in which all elements of the cyclic substituent have p-orbitals and these p-orbitals form conjugation, and includes monocyclic or fused-ring polycyclic (i.e., rings sharing adjacent pairs of carbon atoms) functional groups.

[0025] Also, unless otherwise defined herein, "hetero" means containing 1 to 10 heteroatoms independently selected from N, O, S, and P respectively.

[0026] In this description, "heterocycloalkyl group" means, unless otherwise defined, containing at least 1 heteroatom selected from the group consisting of N, O, S, P, and Si within the cycloalkyl group.

[0027] In this description, "heteroaryl group" means containing at least 1 heteroatom selected from the group consisting of N, O, S, P, and Si within the aryl group. Two or more heteroaryl groups may be directly linked through a sigma bond, or when the heteroaryl group contains two or more rings, the two or more rings may be fused to each other. When the heteroaryl group is a fused ring, each ring can contain 1 to 3 of the heteroatoms.

[0028] Unless otherwise specifically mentioned herein, the weight average molecular weight is measured using Gel Permeation Chromatography (GPC) of the 1200 series from Agilent Technologies after dissolving the powder sample in tetrahydrofuran (THF) (the column is LF - 804 from Shodex, and the standard sample is polystyrene from Shodex).

[0029] Also, unless otherwise defined herein, "*" indicates the connection point of the structural unit or moiety of the compound.

[0030] Hereinafter, the composition for the photoresist upper layer film according to one embodiment will be described.

[0031] The present invention relates to a photosensitive resist upper layer film composition capable of improving the sensitivity of a photosensitive resist and selectively reducing the acid concentration in the upper layer of the photosensitive resist during the fine pattern formation process of photolithography using high-energy rays such as EUV (Extreme ultraviolet; wavelength 13.5 nm), thereby improving the IPU (In-Point Uniformity) of the C / H (contact hole) pattern, the LER (line edge roughness) / LWR (line width roughness) of the L / S (line and space) pattern, and the IPU of the Pillar pattern. The present invention also relates to a method for forming a photosensitive resist pattern using such an upper layer film.

[0032] Specifically, the composition for the resist upper layer film according to one embodiment includes a copolymer containing a first structural unit represented by the following chemical formula M-1, a second structural unit represented by the following chemical formula M-2, and a third structural unit represented by one of the following chemical formulas M-3A, M-3B, and M-3C; and a solvent. The copolymer has an OHV (OH value) of 5 to 100 mgKOH / g.

[0033]

Chemical formula

[0034]

Chemical formula

[0035] The composition for the photoresist upper layer film according to the above embodiment is applied on the upper part of the photoresist layer, which can not only increase the sensitivity of the photoresist, but also significantly improve the LER / LWR of the L / S pattern, the IPU of the C / H pattern, and the IPU of the Pillar pattern.

[0036] The first structural unit contained in the copolymer in the composition can protect the photoresist while minimizing the influence on the photoresist due to its property of being well dissolved in a solvent that has little reactivity with the photoresist. The second structural unit can improve the sensitivity by enhancing EUV absorption. The third structural unit can react with the acid generated in excess by exposure in the upper part of the photoresist layer by containing a functional group that can react with the acid, thereby reducing the acid concentration and improving the rounding profile of the upper part of the photoresist to be rectangular, and improving the IPU or LWR of the pattern.

[0037] On the other hand, if it remains even after the development of the composition for the photoresist upper layer film, it may cause problems such as scum defects in the L / S pattern or not-open defects in the C / H pattern, resulting in a decrease in product yield.

[0038] However, the composition for the photoresist upper layer film according to one embodiment can be removed in the development process and can avoid the problem of defects in various patterns.

[0039] OHV (OH value) is a value indicating the amount of hydroxyl groups (-OH) per 100 g of the sample in mg of KOH, and the analysis method can be found from ASTM, etc.

[0040] The OHV according to an embodiment of the present invention can be measured by the following method.

[0041] A certain amount of copolymer is added to a container filled with a phthalic acid hydrate solution and reacted at a high temperature. Then, while titrating with a 0.5N NaOH (or KOH) aqueous solution, the pH is observed, and the amount of NaOH (or KOH) required to reach the inflection point is measured. Separately, a blank test is carried out to measure the amount of NaOH (or KOH) required to reach the pH inflection point in the same manner as above. Then, based on the measured values, the OHV of the copolymer is calculated by the following formula 1.

[0042] <Formula 1> mg number of KOH (mgKOH / g) / equivalent of OH = 56,100 / equivalent of OH As an example, the copolymer has an OHV (OH value) of 5 to 90 mgKOH / g, specifically 5 to 80 mgKOH / g, more specifically 5 to 70 mgKOH / g, and most specifically 5 to 68 mgKOH / g.

[0043] In the chemical formula M-2, when m1 is 2 or more, each O-R 6 may be the same as or different from each other.

[0044] In the chemical formula M-2, when 5 - m1 is 2 or more, each R 7 may be the same as or different from each other.

[0045] In the chemical formula M-3A, when n1 is 2 or more, each R 10 may be the same as or different from each other.

[0046] In the chemical formula M-3A, when n1 is 2 or more, each R 11 may be the same as or different from each other.

[0047] In the chemical formula M-3B, when n2 is 2 or more, each R 19 may be the same as or different from each other.

[0048] In the chemical formula M-3B, when n2 is 2 or more, each R 20may be the same as or different from each other.

[0049] In the chemical formula M-3B, when n2 is 2 or more, each R 21 may be the same as or different from each other.

[0050] In the chemical formula M-3B, when n2 is 2 or more, each R 22 may be the same as or different from each other.

[0051] In the chemical formula M-3C, when n3 is 2 or more, each R 17 may be the same as or different from each other.

[0052] In the chemical formula M-3C, when n3 is 2 or more, each R 18 may be the same as or different from each other.

[0053] R 5 , L 1 and L 2 at least one of which means containing fluorine and a hydroxy group, R 5 is a C1-C10 alkyl group substituted with at least one fluorine and at least one hydroxy group, or L 1 and L 2 at least one of which is a C1-C10 alkylene group substituted with one or more fluorines and one or more hydroxy groups, or L 1 and L 2 at least one of which is a C1-C10 alkylene group substituted with one or more fluorines and at least one of the remainder is a C1-C10 alkylene group substituted with one or more hydroxy groups, or R 5 is fluorine, and L 1 and L 2 at least one of which is a C1-C10 alkylene group substituted with one or more hydroxy groups, or R 5 ​is a hydroxy group, L 1 and L 2 at least one of which is a C1-C10 alkylene group substituted with one or more fluorines, or R 5 is a C1-C10 alkyl group substituted with one or more fluorines and one or more hydroxy groups, or R 5 is a C1-C10 alkyl group substituted with one or more hydroxy groups and one or more C1-C10 fluoroalkyl groups can be included.

[0054] As an example, the first structural unit may be represented by the following Chemical Formula 1.

Chemical formula

[0055] In the above formula 1, when m2 is 2 or more, each R d may be the same or different from each other.

[0056] In the above formula 1, when m2 is 2 or more, each R e may be the same or different from each other.

[0057] In the above formula 1, when m3 is 2 or more, each R f may be the same or different from each other.

[0058] In the above formula 1, when m3 is 2 or more, each R g may be the same or different from each other.

[0059] R d , R e , R f , R g and R 5 At least one of the groups contains fluorine and a hydroxyl group. R d , R e , R f , R g and R 5 at least one of the following is independently a fluorine or a hydroxyl group; R d , R e , R f , R g and R 5 at least one of the above independently contains a C1-C10 alkyl group substituted with one or more fluorine groups and a C1-C10 alkyl group substituted with one or more hydroxy groups; or R d , R e , R f , R g and R 5 at least one of each independently contains one or more hydroxyl groups and one or more fluorine-substituted C1-C10 alkyl groups; or R d , Re , R f , R g and R 5 at least one of them independently contains a C1-C10 alkyl group substituted with one or more hydroxy groups and one or more C1-C10 fluoroalkyl groups, or R d , R e , R f , R g and R 5 at least one of them is fluorine and at least one of the rest is a hydroxy group, or R d , R e , R f , R g and R 5 at least one of them is fluorine and at least one of the rest contains a C1-C10 alkyl group substituted with one or more hydroxy groups, or R d , R e , R f , R g and R 5 at least one of them is a hydroxy group and at least one of the rest contains a C1-C10 alkyl group substituted with one or more fluorines, or R d , R e , R f , R g and R 5 including the case where at least one of them is a C1-C20 alkyl group substituted with one or more fluorines and at least one of the rest is a C1-C20 alkyl group substituted with one or more hydroxy groups.

[0060] For example, the said R 1 is hydrogen or a methyl group, the said X 1 is a single bond, O or NR a (wherein R a is hydrogen, deuterium, or a C1-C10 alkyl group), the said R 5can be fluorine, a hydroxy group, a C1-C10 alkyl group substituted with at least one fluorine, or a C1-C10 alkyl group substituted with at least one hydroxy group.

[0061] As an example, at least one of R f , R g and R 5 in Chemical Formula 1 can contain fluorine and a hydroxy group.

[0062] As a specific example, at least one of R f and R g in Chemical Formula 1 is fluorine or a C1-C10 alkyl group substituted with at least one fluorine, and R 5 can be a hydroxy group or a C1-C10 alkyl group substituted with at least one hydroxy group.

[0063] As a specific example, at least one of R f and R g in Chemical Formula 1 is a hydroxy group or a C1-C10 alkyl group substituted with at least one hydroxy group, and R 5 can be fluorine or a C1-C10 alkyl group substituted with at least one fluorine.

[0064] As a specific example, R f in Chemical Formula 1 is a hydroxy group or a C1-C10 alkyl group substituted with at least one hydroxy group, R g is fluorine or a C1-C10 alkyl group substituted with at least one fluorine, and R 5 can be a hydroxy group, fluorine, or a C1-C10 alkyl group substituted with at least one of fluorine and a hydroxy group.

[0065] As a specific example, at least one of R f and R g in Chemical Formula 1 is fluorine or a C1-C10 alkyl group substituted with at least one fluorine, and R5 may be a hydroxy group or a C1-C5 alkyl group substituted with at least one of a hydroxy group and a substituted C1-C5 fluoroalkyl group.

[0066] For example, the first structural unit may be selected from the following Group I. [Chemical formula] In the above Group I, R 1 is independently hydrogen or a methyl group, and * is the linking point.

[0067] As a specific example, the second structural unit may be represented by any one of the following Chemical Formulas 2-1 to 2-4. [Chemical formula] In the above Chemical Formulas 2-1 to 2-4, R 2 is hydrogen or a methyl group, R 6 R 6a and R 6b are independently hydrogen or C(=O)R b where R b is a substituted or unsubstituted C1-C5 alkyl group, R 7a R 7b R 7c and R 7d are independently hydrogen, halogen, hydroxy group, substituted or unsubstituted C1-C10 alkyl group, or a combination thereof, and * is the linking point.

[0068] As an example, at least one of the above R 7 may be halogen.

[0069] As a specific example, the above R 7At least one of them may be an iodine group.

[0070] Among the second structural units, when an iodine group is included, the sensitivity can be further improved.

[0071] For example, the second structural unit may be selected from the following Group II.

[0072]

Chemical formula

[0073] As an example, the said L 3 ~L 7 are each independently a single bond, a substituted or unsubstituted C1-C5 alkylene group, or a substituted or unsubstituted phenylene group, R 8 ~R 14 are each independently hydrogen or a substituted or unsubstituted C1-C10 alkyl group, n1 can be an integer of 1 or 2.

[0074] As an example, n1 of the said chemical formula M-3A can be one of the integers from 1 to 5.

[0075] As an example, n2 of the said chemical formula M-3B can be one of the integers from 2 to 4.

[0076] As an example, n3 of the said chemical formula M-3C can be one of the integers from 1 to 5.

[0077] For example, the third structural unit may be selected from the following Group III.

Chemical formula

[0078] The copolymer may contain 30 to 95 mol% of the first structural unit, 1 to 20 mol% of the second structural unit, and 5 to 50 mol% of the third structural unit, based on the total amount of the structural units in the copolymer.

[0079] For example, the copolymer may contain 55 to 90 mol% of the first structural unit, 5 to 15 mol% of the second structural unit, and 5 to 30 mol% of the third structural unit, based on the total amount of the structural units in the copolymer. Most specifically, the copolymer may contain 60 to 85 mol% of the first structural unit, 5 to 15 mol% of the second structural unit, and 5 to 25 mol% of the third structural unit.

[0080] When the molar ratio of each structural unit contained in the copolymer is within the above range, it can be excellently soluble in an organic solvent and uniformly coated on a pattern.

[0081] The copolymer may have a weight average molecular weight (Mw) of 1,000 g / mol to 15,000 g / mol. For example, it may have a weight average molecular weight of about 2,000 g / mol to 15,000 g / mol, for example, about 3,000 g / mol to 15,000 g / mol, for example, about 4,000 g / mol to 10,000 g / mol, but is not limited thereto. When the weight average molecular weight of the copolymer is within the above range, the carbon content and solubility in a solvent of the resist upper layer film composition containing the copolymer can be adjusted and optimized.

[0082] The copolymer may be contained in an amount of 0.1 wt% to 10 wt% based on the total weight of the resist upper layer film composition. By being contained within the above range, the resist upper layer film can be easily removed.

[0083] In the most specific embodiment, the copolymer can be selected from those listed in Group IV below.

Chemical formula

Chemical formula

[0084] For example, x:y:z can be 73:10:17 or 76:8:16 or 77:9:14.

[0085] The solvent can be an ether solvent represented by Chemical formula 4 below.

Chemical formula

[0086] For example, the ether solvent can be selected from diisopropyl ether, dipropyl ether, diisoamyl ether, diamyl ether, dibutyl ether, diisobutyl ether, di-sec-butyl ether, dihexyl ether, bis(2-ethylhexyl) ether, didecyl ether, diundecyl ether, didodecyl ether, ditetradecyl ether, hexadecyl ether, butyl methyl ether, butyl ethyl ether, butyl propyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, tert-butyl propyl ether, di-tert-butyl ether, cyclopentyl methyl ether, cyclohexyl methyl ether, cyclopentyl ethyl ether, cyclohexyl ethyl ether, cyclopentyl propyl ether, cyclopentyl-2-propyl ether, cyclohexyl propyl ether, cyclohexyl-2-propyl ether, cyclopentyl butyl ether, cyclopentyl-tert-butyl ether, cyclohexyl butyl ether, cyclohexyl-tert-butyl ether, 2-octanone, 4-heptanone, and combinations thereof.

[0087] The ether solvent can have sufficient solubility or dispersibility in the aforementioned composition.

[0088] On the other hand, the composition for the resist upper layer film can further include one or more other polymers among acrylic resins, epoxy resins, novolak resins, glycoluril resins, and melamine resins, but is not limited thereto.

[0089] The composition for the resist upper layer film can further include additives such as a surfactant, a thermal acid generator, a plasticizer, or a combination thereof.

[0090] For the surfactant, for example, alkylbenzene sulfonates, alkylpyridinium salts, polyethylene glycol, quaternary ammonium salts, etc. can be used, but are not limited thereto.

[0091] The thermal acid generator can be, for example, an acidic compound such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid or / and benzoin tosylate, 2-nitrobenzyl tosylate, and other alkyl esters of organic sulfonic acids, etc., but is not limited thereto.

[0092] The usage amounts of these additives can be easily adjusted according to the desired physical properties and can also be omitted.

[0093] On the other hand, according to another embodiment, a method for forming a pattern using the above-described composition for a resist upper layer film can be provided. As an example, the manufactured pattern can be a photoresist pattern.

[0094] The pattern forming method according to an embodiment includes a step of applying a photoresist composition on a substrate and heating to form a photoresist film, a step of applying the above-described composition for a resist upper layer film on the photoresist film and heating to form an upper layer film, and a step of exposing and developing the upper layer film and the photoresist film to form a resist pattern.

[0095] Hereinafter, a method for forming a pattern using the above-described composition for a resist upper layer film will be described with reference to FIG. 1. FIG. 1 is a schematic diagram for explaining a pattern forming method using the composition for a resist upper layer film according to the present invention.

[0096] Referring to FIG. 1, first, an object to be etched is provided. As an example of the object to be etched, it can be a thin film formed on a semiconductor substrate. Hereinafter, the description will be made only when the object to be etched is a thin film. The surface of the thin film is cleaned to remove contaminants remaining on the thin film. The thin film can be, for example, a silicon nitride film, a polysilicon film, or a silicon oxide film.

[0097] Apply a photoresist composition onto the thin film and heat it to form a photoresist film 101 (1). Next, apply the composition for the upper photoresist film described above onto the photoresist film and heat it to form an upper photoresist film 30 (2).

[0098] The heating can be performed at a temperature of 80°C to 500°C.

[0099] Next, expose the upper photoresist film and the photoresist film to high-energy irradiation rays.

[0100] As an example, the high-energy irradiation rays that can be used in the exposure step include light having a high-energy wavelength such as EUV (Extreme Ultra Violet; wavelength 13.5 nm), E-Beam (electron beam), etc.

[0101] Next, perform a post-exposure bake (PEB). The post-exposure bake can be performed at a temperature of about 80°C to about 200°C. By performing the post-exposure bake, the exposed regions in the photoresist film, that is, the regions not shielded by the patterned mask, are changed to a property of being dissolved in the developer, so that they have different solubilities from the unexposed regions of the photoresist film.

[0102] A photoresist pattern 102b can be formed by using a developer to dissolve and remove the photoresist film and the upper photoresist film corresponding to the exposed regions (3).

[0103] Specifically, the developer can be an alkaline developer or a developer containing an organic solvent (hereinafter, an organic-based developer).

[0104] As the alkaline developer, usually, a quaternary ammonium salt represented by tetramethylammonium hydroxide is used, but other alkaline aqueous solutions such as inorganic alkalis, primary to tertiary amines, alcohol amines, and cyclic amines can also be used.

[0105] Further, the alkaline developer may contain an appropriate amount of alcohols and / or surfactants. The alkali concentration of the alkaline developer can be, for example, 0.1 to 20% by mass, and the pH of the alkaline developer can be, for example, 10 to 15.

[0106] The organic developer may be a developer containing at least one organic solvent selected from the group consisting of a ketone solvent, an ester solvent, an alcohol solvent, an amide solvent, an ether solvent, and a hydrocarbon solvent.

[0107] Examples of the ketone solvent include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone (methyl amyl ketone), 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate.

[0108] Examples of the ester solvent include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, butyl butyrate, methyl 2-hydroxyisobutyrate, isoamyl acetate, isobutyl isobutyrate, and butyl propionate.

[0109] As the alcohol-based solvent, amide-based solvent, ether-based solvent, and hydrocarbon-based solvent, known solvents can be used.

[0110] The above solvents may be mixed in plurality, or may be mixed with solvents other than the above or water. The water content in the whole developer is preferably less than 50% by weight, more preferably less than 20% by weight, still more preferably less than 10% by weight, and particularly preferably substantially free of water.

[0111] The content of the organic solvent in the organic-based developer is preferably 50 to 100% by weight, more preferably 80 to 100% by weight, still more preferably 90 to 100% by weight, and particularly preferably 95 to 100% by weight with respect to the total amount of the developer.

[0112] The organic-based developer may contain an appropriate amount of a known surfactant as necessary.

[0113] The content of the surfactant is usually 0.001 to 5% by weight, preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% by weight with respect to the total amount of the developer.

[0114] The organic-based developer may contain the above-mentioned inhibitor.

[0115] Next, the thin film exposed by applying the photoresist pattern as an etching mask is etched. As a result, the thin film is formed into a thin film pattern.

[0116] The etching of the thin film can be performed by dry etching using, for example, an etching gas, and the etching gas can use, for example, CHF3, CF4, Cl2, BCl3, and a mixed gas thereof.

[0117] In the previously performed exposure process, the thin film pattern formed using the photoresist pattern formed by the exposure process performed using an EUV light source can have a width corresponding to the photoresist pattern. As an example, it can have the same width as the photoresist pattern, which can be 5 nm to 100 nm. For example, the thin film pattern formed by the exposure process performed using an EUV light source can have widths such as 5 nm to 90 nm, 5 nm to 80 nm, 5 nm to 70 nm, 5 nm to 60 nm, 5 nm to 50 nm, 5 nm to 40 nm, 5 nm to 30 nm, 5 nm to 20 nm, similar to the photoresist pattern, and more specifically, it can be formed with a width of 20 nm or less.

Example

[0118] Hereinafter, the present invention will be described in more detail through examples related to the synthesis of the aforementioned polymer and the production of a composition for a photoresist upper layer film containing the same. However, the present invention is not technically limited by the following examples.

[0119] Synthesis Example Synthesis Example 1 Into a 250 mL two-neck round bottom flask, 13.39 g of the compound represented by the above chemical formula 1a (CHEMOPTICS), 1.86 g of the compound represented by the following chemical formula 1b (DIHS, Accela ChemBio), 2.16 g of hydroxyl butyl acrylate (4-HBA; Oi Chemical Co., Ltd.), and 71.4 g of diisoamyl ether (DIAE) were added. After that, it was heated so that the internal temperature reached 115°C. Once the internal temperature reached 115°C, 13.82 g of a 25 wt% V-601 / DIAE solution (3.45 g of V-601) was gradually added. After 6 hours, the reaction solution was cooled to room temperature, and the reaction mixture was concentrated to 50% solids content. After adding 120 g of heptane to the concentrated solution, the resulting polymer was filtered. After completely dissolving the filtered polymer in 12 g of DIAE, the process of adding 270 g of heptane and precipitating was repeated twice, and then it was completely dried to finally produce copolymer R1 (Mw = 5,000).

[0120]

Chemical formula

[0121]

Chemical formula

[0122] Synthesis Example 2 Except that 1.74 g of hydroxyl ethyl acrylate (HEA; Oi Chemical Co., Ltd.) was used instead of 4-HBA, it was carried out in the same manner as in Synthesis Example 1 to produce copolymer R2 (Mw = 5,300).

[0123] Synthesis Example 3 The copolymer R3 (Mw = 5,500) was produced in the same manner as in Synthesis Example 1, except that 1.95 g of hydroxyl propyl acrylate (HPA; Daiichi Kigenso Co., Ltd.) was used instead of 4-HBA.

[0124] Synthesis Example 4 The copolymer R4 (Mw = 5,900) was produced in the same manner as in Synthesis Example 1, except that 5.16 g of caprolactone acrylate (Tone M-100; Dow Chemical Company) was used instead of 4-HBA.

[0125] Synthesis Example 5 The copolymer R5 (Mw = 5,500) was produced in the same manner as in Synthesis Example 1, except that 8.83 g of the compound represented by the following Chemical Formula 1c (HALOCARBON) was used instead of the compound represented by Chemical Formula 1a.

[0126]

Chemical Formula

[0127] Synthesis Example 6 The copolymer R6 (Mw = 5,500) was produced in the same manner as in Synthesis Example 1, except that 8.41 g of the compound represented by the following Chemical Formula 1d (HALOCARBON) was used instead of the compound represented by Chemical Formula 1a.

[0128]

Chemical Formula

[0129] Synthesis Example 7 The copolymer R7 (Mw = 5,300) was produced in the same manner as in Synthesis Example 1, except that 9.25 g of the compound represented by the following Chemical Formula 1e (HALOCARBON) was used instead of the compound represented by Chemical Formula 1a.

[0130] [Chemical formula]

[0131] Comparative Synthesis Example 1 A copolymer R8 (Mw = 7,500) was produced in the same manner as in Synthesis Example 1, except that 8.92 g of the compound represented by Chemical Formula 1a and 3.61 g of 4-HBA were used.

[0132] Comparative Synthesis Example 2 A copolymer R9 (Mw = 3,100) was produced in the same manner as in Synthesis Example 1, except that 5.58 g of the compound represented by Chemical Formula 1b and 3.45 g of 4-HBA were used.

[0133] Comparative Synthesis Example 3 A copolymer R10 (Mw = 2,700) was produced in the same manner as in Synthesis Example 1, except that 11.15 g of the compound represented by Chemical Formula 1a and 9.3 g of the compound represented by Chemical Formula 1b were used and 4-HBA was not used.

[0134] Comparative Synthesis Example 4 A copolymer R11 (Mw = 4,200) was produced in the same manner as in Synthesis Example 1, except that 5.58 g of the compound represented by Chemical Formula 1b and 5.05 g of 4-HBA were used and the compound represented by Chemical Formula 1a was not used.

[0135] Comparative Synthesis Example 5 A copolymer R12 (Mw = 8,100) was produced in the same manner as in Synthesis Example 1, except that 13.39 g of the compound represented by Chemical Formula 1a and 2.88 g of 4-HBA were used and the compound represented by Chemical Formula 1b was not used.

[0136] Evaluation 1: Evaluation of Solubility 1 g of each copolymer produced from Synthesis Examples 1 to 7 and Comparative Synthesis Examples 1 to 5 was taken and put into 50 g of DIAE (2 wt%), stirred for 24 hours, and the presence or absence of precipitation was observed with the naked eye. The results are shown in Table 1 below.

[0137] [Evaluation Criteria] Solubility ○: No foreign matter, transparent liquid state Solubility △: No precipitate, slightly opaque state Solubility X: Presence of precipitate or completely turbid state

[0138] Evaluation 2: Evaluation of developability After applying the composition for the photoresist upper layer film according to the examples and comparative examples on a silicon substrate by spin-on coating method, it was heat-treated on a hot plate at 110 °C for 1 minute to form a photoresist upper layer film with a thickness of about 5 nm. Then, it was developed with a 2.38% aqueous solution of tetramethylammonium hydroxide, and after heat-treatment on a hot plate at 110 °C for 1 minute, the change in the thickness of the photoresist upper layer film was measured, and the results are shown in Table 1 below.

[0139] * Residual film after development (%) = [(thickness of upper layer film before development (nm) - thickness of upper layer film after development (nm)) x 100] / thickness of upper layer film before development (nm) [Evaluation Criteria] ○: When it is 98% or more according to the above formula △: When it is less than 98% and 90% or more according to the above formula X: When it is less than 90% according to the above formula

[0140] Evaluation 3: Evaluation of patterning After forming a resist lower layer film (thickness 50 Å) and an E-Beam photoresist thin film (thickness 700 Å) on an 8-inch silicon substrate, the composition for the photoresist upper layer film manufactured in the examples and comparative examples was applied by spin-on coating method, and then heat-treated on a hot plate at 110 °C for 1 minute to form a photoresist upper layer film with a thickness of about 5 nm.

[0141] For the wafer with the photoresist upper layer film formed thereon, a line and space pattern is formed in the Focus-Energy Matrix (FEM) format using an E-Beam facility (JBX-9300FS from JEOL). The optimal sensitivity capable of forming a critical dimension (CD) of 50 nm is confirmed by an interpolation method, and the resulting values are shown in Table 1 below. After confirming the optimal sensitivity, the line width roughness (LWR) variation is measured using a Hitatchi CD-SEM facility with the corresponding energy shot. To enhance the reliability of the variation values, 500 points of the same pattern are measured within a shot, and the final average values are shown in Table 1 below.

[0142]

Table 1

[0143] Referring to Table 1, when the composition for the resist upper layer film according to the embodiment of the present invention is applied, it can be confirmed that not only is it excellent in sensitivity, but also it is excellent in the LWR improvement effect.

[0144] As described above, specific embodiments of the present invention have been described and illustrated. However, the present invention is not limited to the described embodiments, and it is obvious to those with ordinary knowledge in the technical field that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modified examples or variations should not be individually understood from the technical idea or perspective of the present invention, and it can be said that the modified embodiments belong to the scope of the claims of the present invention.

Explanation of Reference Signs

[0145] 1. The step of forming a photoresist film, 2. The step of forming a photoresist upper layer film, 3. The step of exposing and developing the photoresist film and the photoresist upper layer film to form a resist pattern, 30. The photoresist upper layer film, 100. The substrate, 101. The photoresist film, 102b. The resist pattern.

Claims

1. A copolymer comprising a first structural unit represented by the following chemical formula M-1, a second structural unit represented by the following chemical formula M-2, and a third structural unit represented by at least one of the following chemical formulas M-3A, M-3B, and M-3C; and containing a solvent, A composition for a resist upper layer film, wherein the copolymer has an OHV (OH value) of 5 to 100 mgKOH / g: 【Chemical 1】 In the chemical formulas M-1 and M-2, R １ and R ２ are each independently hydrogen or a substituted or unsubstituted C1-C10 alkyl group, L １ and L ２ each independently represents a single bond, a substituted or unsubstituted C1-C10 alkylene group, or a combination thereof, X １ is a single bond, -O-, -S-, -S(O)-, -S(O) ２ -, -C(O)-, -(CO)O-, -O(CO)-, -O(CO)O-, -NR ａ -(where R ａ is hydrogen, deuterium, or a substituted or unsubstituted C1-C10 alkyl group), or a combination thereof, R ５ is hydrogen, fluorine, a hydroxy group, a substituted or unsubstituted C1-C20 alkyl group, or a combination thereof, R ６ is hydrogen or C(=O)R ｂ wherein R ｂ is a substituted or unsubstituted C1-C10 alkyl group, R ５ 、 L １ and L ２ at least one of which contains a fluorine and a hydroxy group, R ７ is hydrogen, halogen, a hydroxy group, a substituted or unsubstituted C1-C10 alkyl group, or a combination thereof, m1 is one of the integers from 1 to 4, * is the connection point; [Chemical Formula 2] In the chemical formulas M-3A to M-3C, R ３ , R ４ and R ８ ~R ２２ are each independently hydrogen or a substituted or unsubstituted C1-C10 alkyl group, n1 and n3 are each independently one of the integers from 1 to 10, n2 is one of the integers from 2 to 5, n4 is one of the integers from 1 to 5, * is the connection point.

2. The composition for a resist upper layer film according to Claim 1, wherein the first structural unit is represented by the following chemical formula 1. 【Chemical Formula 3】 (In the chemical formula 1, R １ is hydrogen or a substituted or unsubstituted C1-C10 alkyl group, R ｄ 、R ｅ 、R ｆ 、R ｇ and R ５ are each independently hydrogen, fluorine, a hydroxy group, a substituted or unsubstituted C1-C20 alkyl group, or a combination thereof, m2 and m3 are each independently one of the integers from 1 to 10, X １ is a single bond, -O-, -S-, -S(O)-, -S(O) ２ -, -C(O)-, -(CO)O-, -O(CO)-, -O(CO)O-, -NR ａ -(where R ａ is hydrogen, deuterium, or a substituted or unsubstituted C1-C10 alkyl group), or a combination thereof, R ｄ 、 R ｅ 、 R ｆ 、 R ｇ and R ５ At least one of them contains fluorine and a hydroxy group.)

3. The composition for a resist upper layer film according to Claim 1, wherein the first structural unit is at least one selected from the following Group I. [Chemical Formula 4] (In the Group I, R １ is, independently of one another, hydrogen or a methyl group, and * is the point of attachment.)

4. The composition for a resist upper layer film according to Claim 1, wherein the second structural unit is represented by any one of the following chemical formulas 2-1 to 2-4. 【Chemical Formula 5】 (In the chemical formulas 2-1 to 2-4, R ２ is a hydrogen or methyl group, R ６ 、R ６ａ 、and R ６ｂ are each independently hydrogen or C(=O)R ｂ wherein R ｂ is a substituted or unsubstituted C1-C5 alkyl group, R ７ａ 、R ７ｂ 、R ７ｃ 、and R ７ｄ are each independently hydrogen, halogen, a hydroxy group, a substituted or unsubstituted C1-C10 alkyl group, or a combination thereof, * is the connection point.)

5. The aforementioned R ７ The composition for a resist upper layer film according to claim 1, wherein at least one of them is a halogen.

6. The aforementioned R ７ The resist upper layer film composition according to claim 1, wherein at least one of them is an iodine group.

7. The composition for a resist upper layer film according to Claim 1, wherein the second structural unit is at least one selected from the following Group II. ​ (In the Group II, R ２ is, independently of one another, hydrogen or a methyl group, and * is the point of attachment.)

8. The composition for a resist upper layer film according to Claim 1, wherein n1 of the chemical formula M-3A is one of the integers from 1 to 5.

9. The composition for a resist upper layer film according to Claim 1, wherein n2 of the chemical formula M-3B is one of the integers from 2 to 4.

10. The composition for a resist upper layer film according to Claim 1, wherein n3 of the chemical formula M-3C is one of the integers from 1 to 5.

11. The composition for a resist upper layer film according to Claim 1, wherein the third structural unit is at least one selected from the following Group III. [Chemical Formula 7] (In the Group III, R ３ , R ４ and R １２ are each independently hydrogen or a methyl group, and * is the point of attachment.)

12. The copolymer contains 30 to 95 mol% of the first structural unit, 1 to 20 mol% of the second structural unit, and 5 to 50 mol% of the third structural unit, based on the total amount of the structural units in the copolymer. The composition for a resist upper layer film according to claim 1.

13. The weight average molecular weight of the copolymer is 1,000 g / mol to 15,000 g / mol. The composition for a resist upper layer film according to claim 1.

14. The copolymer is selected from those listed in Group IV below. The composition for a resist upper layer film according to claim 1. 【Chemical 8】 【Chemical Formula 9】 (In the said Group IV, R １ 、 R ２ and R ７ is, independently of one another, hydrogen or a methyl group, x is 30 to 95 mol%, y is 2 to 20 mol%, and z is 5 to 50 mol%. )

15. The copolymer is contained in an amount of 0.1% by weight to 10% by weight based on the total weight of the composition for a resist upper layer film. The composition for a resist upper layer film according to claim 1.

16. The solvent is an ether solvent represented by the following Chemical Formula 4. The composition for a resist upper layer film according to claim 1. 【Chemical Formula 10】 (In the said Chemical Formula 4, R ８ and R ９ is each independently a substituted or unsubstituted C3-C20 alkyl group.)

17. A step of applying a photoresist composition on a substrate and heating to form a photoresist film, A step of applying the composition for a resist upper layer film according to any one of claims 1 to 16 on the photoresist film and heating to form an upper layer film, and A step of exposing and developing the upper layer film and the photoresist film to form a resist pattern A pattern forming method comprising.

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