Narrow line cut mask process

Abstract

A method of patterning a substrate includes providing a first relief pattern on a substrate, the first relief pattern comprising a first resist, coating the first relief pattern with a solubility modifier, depositing a second resist onto the first resist pattern such that the second resist is in contact with the first relief pattern, and diffusing the solubility modifier a predetermined distance into the second resist to provide a solubility-altered region of the second resist adjacent to the first relief pattern. The method then includes developing the second resist such that the solubility-altered region is dissolved to provide a gap between the first relief pattern and the second resist in which a portion of the substrate is exposed, and etching the substrate using the first relief pattern and the second resist as a combined etch mask.

Description

Background Art

[0001] The microfabrication of semiconductor devices involves various processes such as film formation, pattern formation, and pattern transfer. Materials and films are deposited on a substrate by spin coating, evaporation, and other deposition processes. Pattern formation is typically carried out by exposing a photosensitive film, also known as a photoresist, to a pattern of actinic radiation using a 248 nm KrF excimer laser, a 193 nm ArF excimer laser, or a 13.5 nm extreme ultraviolet (EUV) exposure tool, and then developing the photoresist to form a relief pattern. The relief pattern then acts as an etching mask covering the part of the substrate that is not to be etched when one or more etching processes are applied to the substrate. Line cuts are achieved on the substrate using such photolithography processes, where each cut is independently positioned using a separate lithographic exposure. This is difficult, especially when the cuts have to be placed close to each other, as the line width decreases.

[0002] Typically, before pattern formation, the pattern is first etched onto one or more transfer layers such as a hard mask layer or a bottom antireflective coating (BARC) layer, and then transferred to the substrate layer. Therefore, current microfabrication technologies require many processes and are often very expensive to implement.

Summary of the Invention

Means for Solving the Problems

[0003] This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0004] In one aspect, embodiments disclosed herein relate to a method of patterning a substrate, comprising providing a first relief pattern on the substrate, wherein the first relief pattern includes a first resist; coating the first relief pattern with a solubility modifier; depositing a second resist on the first resist pattern such that the second resist is in contact with the first relief pattern; diffusing the solubility modifier into the second resist by a predetermined distance to provide a region where the solubility of the second resist has changed, the region where the solubility of the second resist has changed being adjacent to the first relief pattern; developing the second resist such that the region where the solubility has changed is dissolved, providing a gap in which a portion of the substrate is exposed between the first relief pattern and the second resist; and etching the substrate using the first relief pattern and the second resist as a combined etching mask.

[0005] In another aspect, embodiments disclosed herein relate to a method of patterning a substrate, comprising providing a first relief pattern on the substrate, wherein the first relief pattern includes a first resist; coating the first relief pattern with a solubility modifier; depositing a second resist on the first resist pattern such that the second resist is in contact with the first relief pattern; diffusing the solubility modifier into the first resist by a predetermined distance to provide a region where the solubility of the first resist is changed, wherein the region where the solubility of the first resist is changed is adjacent to the second resist; developing the first resist such that the region where the solubility is changed is dissolved, providing a gap in which a portion of the substrate is exposed between the first relief pattern and the second resist; and etching the substrate using the first relief pattern and the second resist as a combined etching mask. In yet another aspect, embodiments disclosed herein relate to a coated substrate including a first photoresist layer including a core polymer and a shell polymer, wherein the core polymer and the shell polymer have different dissolution characteristics, and having a second photoresist layer coated on and around the surface of the first photoresist layer, wherein the second photoresist layer includes a polymer.

[0006] Other aspects and advantages of the claimed subject matter will be apparent from the following description and appended claims.

Brief Description of the Drawings

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Embodiments for Carrying out the Invention

[0011] The present disclosure generally relates to a method of patterning a semiconductor substrate. In one or more embodiments, the method includes forming a controlled narrow cut on the substrate. As used herein, the terms “semiconductor substrate” and “substrate” are used interchangeably and can be any semiconductor material including, but not limited to, semiconductor wafers, semiconductor material layers, and combinations thereof. In the present disclosure, the term “photoresist” can be used to refer to a resist material that includes photoacid generation and is patterned using light, while the term “resist” can be used to describe a resist material that is not patterned using light. As defined herein, narrow is understood to mean a width of from about 5 nm to about 30 nm. Thus, the method in the present disclosure can provide cuts having a width of from about 5 nm to about 30 nm. Different from conventional lithographic patterning, the method disclosed herein achieves multiple cuts in one photolithography process, while conventional processes require multiple photolithography processes. Further, the method can include directly cutting narrow lines onto the substrate.

[0012] FIG. 1 shows method 100 in the present disclosure and will be described with reference to FIG. 1. First, method 100 includes providing a first relief pattern on a substrate at block 102. The first relief pattern can be formed using a photolithography process and can be made from a first resist. In method 100, at block 104, the first relief pattern is coated with a solubility modifier. The solubility modifier can be a solubilizer or a hardener based on the polarity of the first resist. Next, at block 106, a second resist is laminated on the first relief pattern, such that any exposed portions of the substrate and the first photoresist are completely covered with the second resist. At block 108, the solubility modifier then diffuses into the second resist, and at block 110, the second resist is developed. The diffusion of the solubility modifier can form regions of changed solubility that can be selectively developed in the second resist, forming trenches where the substrate is exposed. After developing the second resist, the substrate is etched, and at block 112, a pattern of narrow cut lines formed by self-alignment of the features of the second resist can be formed.

[0013] Schematic views of the coated substrate at various points during the above method are shown in FIGS. 2A, 2B, 2C, 2D, and 2E. As used herein, "coated substrate" refers to a substrate coated with one or more layers such as a first photoresist layer and a second resist layer. FIG. 2A shows the substrate including the first relief pattern. FIG. 2B shows the substrate including the first relief pattern coated with a solubility modifier. In FIG. 2C, the second resist is laminated on the substrate and the first relief pattern. FIG. 2D shows the coated substrate after the solubility modifier has diffused into the second resist. Finally, FIG. 2E shows the coated substrate after the second resist has been developed, with a portion of the substrate exposed and etchable. The method of FIG. 1 and the coated substrates shown in FIGS. 2A-2E will be discussed in detail below.

[0014] In block 102 of method 100, a first relief pattern is provided. FIG. 2A shows an example of the first relief pattern 204 on substrate 202. As shown in FIG. 2A, the first relief pattern may include features separated by gaps. A portion of the substrate may be exposed due to the presence of the gaps in the first relief pattern. The features of the first relief pattern may be fabricated from a first resist 203. The first resist may be a photoresist. Generally, a photoresist is a chemically amplified photosensitive composition containing a polymer, a photoacid generator, and a solvent. In one or more embodiments, the first resist contains a polymer. The polymer can be any standard polymer typically used in photoresist materials, and in particular can be a polymer having acid-labile groups. For example, the polymer can be a polymer made from aromatic vinyl monomers such as styrene and p-hydroxystyrene, acrylates, methacrylates, norbornene, and combinations thereof. Monomers containing reactive functional groups may be present in the polymer in a protected form. For example, the -OH group of p-hydroxystyrene can be protected with a tert-butyloxycarbonyl protecting group. Such protecting groups can modify the reactivity and solubility of the polymer contained in the first photoresist. As will be understood by those skilled in the art, various protecting groups can be used for this reason. Examples of acid-labile groups include, for example, tertiary alkyl ester groups, secondary or tertiary aryl ester groups, secondary or tertiary ester groups having a combination of an alkyl group and an aryl group, tertiary alkoxy groups, acetal groups, or ketal groups. Acid-labile groups are generally also referred to in the art as "acid-decomposable groups", "acid-dissociable groups", "acid-dissociable protecting groups", "acid-labile protecting groups", "acid-eliminating groups", and "acid-sensitive groups".

[0015] Upon decomposition, the acid-labile group that forms a carboxylic acid in the polymer is preferably a tertiary ester group of the formula -C(O)OC(R 1 )3, or an acetal group of the formula -C(O)OC(R 2 )2OR 3 , wherein R 1 are each independently a linear C 1-20Alkyl, branched C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight-chain C 2-20 Alkenyl, branched C 3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably straight-chain C 1-6 Alkyl, branched C 3-6 Alkyl, or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, each R 1 includes, as part of its structure, one or more groups optionally selected from -O-, -C(O)-, -C(O)-O- or -S-, and any two R 1 groups may together optionally form a ring, and R 2 is independently hydrogen, fluorine, straight-chain C 1-20 Alkyl, branched C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight-chain C 2-20 Alkenyl, branched C 3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably hydrogen, straight-chain C 1-6 Alkyl, branched C 3-6 Alkyl, or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, each R 2 includes, as part of its structure, one or more groups optionally selected from -O-, -C(O)-, -C(O)-O- or -S-, and R 2 groups may together optionally form a ring, and R 3 is straight-chain C 1-20 Alkyl, branched C 3-20 Alkyl, monocyclic or polycyclic C 3-20 Cycloalkyl, straight-chain C 2-20 Alkenyl, branched C3-20 Alkenyl, monocyclic or polycyclic C 3-20 Cycloalkenyl, monocyclic or polycyclic C 6-20 Aryl, or monocyclic or polycyclic C 2-20 Heteroaryl, preferably linear C 1-6 Alkyl, branched C 3-6 Alkyl or monocyclic or polycyclic C 3-10 Cycloalkyl, each of which is substituted or unsubstituted, and R 3 contains, as part of its structure, optionally one or more groups selected from -O-, -C(O)-, -C(O)-O- or -S-, and one R 2 optionally forms a ring together with R 3 Such monomers are typically aromatic vinyl, (meth)acrylate or norbornene monomers. The total content of polymerized units containing acid-decomposable groups that form carboxylic acid groups in the polymer is typically 10 to 100 mol%, more typically 10 to 90 mol%, or 30 to 70 mol% based on the total polymerized units of the polymer.

[0016] The polymer can further contain monomers containing acid-labile groups during polymerization, and the decomposition of these groups forms alcohol groups or fluoroalcohol groups in the polymer. Suitable such groups include, for example, acetal groups of the formula -COC(R 2 )2OR 3 -, or carbonate ester groups of the formula -OC(O)O-, where R is as defined above. Such monomers are typically aromatic vinyl, (meth)acrylate or norbornene monomers. When present in the polymer, the total content of polymerized units containing acid-decomposable groups that form alcohol groups or fluoroalcohol groups upon decomposition is typically 10 to 90 mol%, more typically 30 to 70 mol% based on the total polymerized units of the polymer.

[0017] In an embodiment where the first resist is a photoresist, the first resist contains a photoacid generator. The photoacid generator is a compound capable of generating an acid upon irradiation with actinic rays or actinic ray radiation. The photoacid generator can be selected from known compounds capable of generating an acid upon irradiation with actinic rays or radiation used for cationic photopolymerization initiators, radical photopolymerization initiators, photobleaching agents for dyes, photochromic agents, microlithography resists, etc., and mixtures thereof can be used. Examples of photoacid generators include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

[0018] Suitable photoacids include, for example, onium salts such as triphenylsulfonium trifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate; dit-butylphenyliodonium perfluorobutanesulfonate, and dit-butylphenyliodonium camphorsulfonate. Nonionic sulfonates and sulfonyl compounds are also known to function as photoacid generators, and examples include nitrobenzyl derivatives such as 2-nitrobenzyl-p-toluenesulfonate, 2,6-dinitrobenzyl-p-toluenesulfonate, and 2,4-dinitrobenzyl-p-toluenesulfonate, sulfonic acid esters such as 1,2,3-tris(methanesulfonyloxy)benzene, 1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and 1,2,3-tris(p-toluenesulfonyloxy)benzene, diazomethane derivatives such as bis(benzenesulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, glyoxime derivatives such as bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime and bis-O-(n-butanesulfonyl)-α-dimethylglyoxime, sulfonic acid ester derivatives of N-hydroxyimide compounds such as N-hydroxysuccinimide methanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate, and halogen-containing triazine compounds such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine and 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine. Suitable non-polymerizable photoacid generators are further described in U.S. Patent No. 8,431,325 by Hashimoto et al. (column 37, lines 11 to 47 and columns 41 to 91).Other suitable sulfonate PAGs include sulfonated esters and sulfonyloxy ketones, nitrobenzyl esters, s-triazine derivatives, benzoin tosylate, t-butylphenyl α-(p-toluenesulfonyloxy)-acetate, and t-butyl α-(p-toluenesulfonyloxy)-acetate, as described in U.S. Pat. Nos. 4,189,323 and 8,431,325. PAGs that are onium salts typically contain anions having a sulfonate group or a non-sulfonate type group, such as a sulfonamidate group, a sulfonimide group, a methide group, or a borate group.

[0019] The resist composition may optionally contain a plurality of PAGs. The plurality of PAGs can be polymerizable, non-polymerizable, or can include both polymerizable PAGs and non-polymerizable PAGs. Preferably, each of the plurality of PAGs is non-polymerizable. Preferably, when a plurality of PAGs are used, the first PAG contains a sulfonate group in the anion, and the second PAG contains an anion that does not contain a sulfonate group, and such anions contain, for example, the above-mentioned sulfonamidate group, sulfonimide group, methide group, or borate group.

[0020] The first relief pattern can be formed by laminating a first resist onto a substrate and developing the first resist. The first resist is developed according to procedures known in the art, such as exposure to actinic radiation, followed by rinsing with a first photoresist developer. To impart a shape or relief pattern to the developed resist, a mask can be used to block a portion of the resist from actinic radiation. After the actinic radiation is irradiated, the unexposed portion of the resist can have a solubility different from that of the exposed portion of the resist. Subsequent rinsing with the first resist developer dissolves either the unexposed portion or the exposed portion. When the unexposed portion of the resist remains after rinsing with the developer, the provided relief pattern is a positive tone developed (PTD) resist. In contrast, when the exposed portion of the resist remains after rinsing with the developer, the provided relief pattern is a negative tone developed resist.

[0021] In some embodiments, the first resist is a positive tone developed (PTD) resist. In such embodiments, the first relief pattern can include a polymer made from the monomer, and any monomer containing a reactive functional group is protected. Thus, the first PTD resist can be organically soluble, whereby the relief pattern can be provided by rinsing with a first resist developer that is basic. Suitable basic first resist developers include quaternary ammonium hydroxides such as tetramethylammonium hydroxide (TMAH).

[0022] In other embodiments, the first resist is a negative resist. In such embodiments, the first relief pattern may include a polymer made from the monomer, and any monomer containing a reactive functional group is not protected. Exposure to actinic radiation causes crosslinking of the polymer in the exposed areas, rendering the polymer insoluble in the developer. Subsequently, the unexposed and thus uncrosslinked areas can be removed using a suitable developer to form the relief pattern.

[0023] In other embodiments, the first resist is a negative tone developed (NTD) resist. Similar to the PTD resist, the NTD resist may include a polymer made from the monomer, and any monomer containing a reactive functional group is protected. Thus, while the first NTD resist may be organically soluble, instead of developing the exposed areas using a first resist developer that is basic, the first relief pattern can be provided by rinsing the first resist using a first resist developer containing an organic solvent. Suitable organic solvents that can be used as the first resist developer include n-butyl acetate (NBA) and 2-heptanone. The tone of the resist (i.e., PTD vs. negative vs. NTD) can affect the subsequent chemical properties applied to the first relief pattern.

[0024] In other embodiments, the first resist optionally contains other additives, and the other additives include at least one of a resin having at least one of a fluorine atom or a silicon atom, a basic compound, a surfactant, an onium carboxylate, a dye, a plasticizer, a photosensitizer, a light absorber, an alkali-soluble resin, a dissolution inhibitor, and a compound for accelerating dissolution in a developer.

[0025] As described above, the first relief pattern may include features separated by gaps. In one or more embodiments, the features of the first relief pattern may have a thickness of about 300 to 3000 Å. The gaps separating the features may leave a portion of the substrate exposed.

[0026] In some embodiments, the first relief pattern is stabilized prior to coating with the solubility modifier. Various resist stabilization techniques, also known as freezing processes, have been proposed, such as ion implantation, UV curing, heat curing, thermal curing, and chemical curing. The techniques are described, for example, in U.S. Patent Application Publication Nos. 2008 / 0063985, 2008 / 0199814, and 2010 / 0330503.

[0027] In block 104 of method 100, the first relief pattern is coated with a solubility modifier. The coated substrate by block 104 is shown in FIG. 2B. The solubility modifier 205 is shown as a thin coating on the first relief pattern 204. The thickness of the solubility modifier coating is not particularly limited and may be varied based on the desired line cut width. The solubility modifier may be a material that is absorbed by the first photoresist by baking and, in some cases, may be referred to herein as an "absorbing material." The process of absorbing the solubility modifier into the first photoresist is described in detail below.

[0028] The composition of the solubility modifier may depend on the tone of the first photoresist. Generally, the solubility modifier can be any chemical that is activated using light or heat. For example, when the first photoresist is a PTD photoresist, the solubility modifier may include an acid or a thermal acid generator. The acid, or in the case of TAG the generated acid, must be sufficient to cause decomposition of the bonds of the polymer acid-decomposable groups in the surface region of the first photoresist pattern by heat, in order to increase the solubility of the first photoresist polymer in a specific developer to be applied. The acid or TAG is typically present in the composition in an amount of about 0.01 to 20% by weight based on the total solids of the solubility modifier.

[0029] Preferred acids are organic acids including non-aromatic acids or aromatic acids, each of which can optionally have a fluorine substitution. Suitable organic acids include, for example, carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, dichloroacetic acid, trichloroacetic acid, perfluoroacetic acid, perfluorooctanoic acid, oxalic acid, malonic acid and succinic acid, hydroxyalkanoic acids such as citric acid, aromatic carboxylic acids such as benzoic acid, fluorobenzoic acid, hydroxybenzoic acid and naphthoic acid, organic phosphoric acids such as dimethylphosphoric acid and dimethylphosphinic acid, and sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, 1-butanesulfonic acid, 1-perfluorobutanesulfonic acid, 1,1,2,2-tetrafluorobutane-1-sulfonic acid, 1,1,2,2-tetrafluoro-4-hydroxybutane-1-sulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid and 1-heptanesulfonic acid, optionally fluorinated alkylsulfonic acids.

[0030] Exemplary aromatic acids that do not contain fluorine include aromatic acids of the following general formula (I).

[0031]

Chemical formula

[0032] [In the formula, R1 independently represents a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C20 aryl group, or a combination thereof, and optionally contains one or more groups selected from carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z1 independently represents a group selected from carboxyl, hydroxy, nitro, cyano, C1-C5 alkoxy, formyl, and sulfonic acid; a and b are independently integers from 0 to 5, and a + b is 5 or less.]

[0033] Exemplary aromatic acids can be represented by the following general formula (II).

[0034] [Chemical formula]

[0035] [In the formula, R2 and R3 each independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C16 aryl group, or a combination thereof, and optionally contain one or more groups selected from carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z2 and Z3 each independently represent a group selected from carboxyl, hydroxy, nitro, cyano, C1-C5 alkoxy, formyl, and sulfonic acid; c and d are independently integers from 0 to 4, and c + d is 4 or less; e and f are independently integers from 0 to 3, and e + f is 3 or less.]

[0036] Additional aromatic acids that can be contained in the solubility modifier include those of the following general formula (III) or (IV).

[0037] [Chemical formula]

[0038] [In the formula, R4, R5, and R6 each independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C12 aryl group, or a combination thereof, and optionally contain one or more groups selected from carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z4, Z5, and Z6 each independently represent a group selected from carboxyl, hydroxy, nitro, cyano, C1-C5 alkoxy, formyl, and sulfonic acid; g and h are independently integers from 0 to 4, where g + h is 4 or less; i and j are independently integers from 0 to 2, where i + j is 2 or less; k and l are independently integers from 0 to 3, where k + l is 3 or less.]

[0039]

Chemical formula

[0040] [In the formula, R4, R5, and R6 each independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C12 aryl group, or a combination thereof, and optionally contain one or more groups selected from carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z4, Z5, and Z6 independently represent a group selected from carboxyl, hydroxy, nitro, cyano, C1-C5 alkoxy, formyl, and sulfonic acid; g and h are independently integers from 0 to 4, where g + h is 4 or less; i and j are independently integers from 0 to 1, where i + j is 1 or less; k and l are independently integers from 0 to 4, where k + l is 4 or less.]

[0041] Suitable aromatic acids can alternatively be of the following general formula (V).

[0042]

Chemical formula

[0043] [In the formula, R7 and R8 each independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C14 aryl group, or a combination thereof, and optionally contain one or more groups selected from carboxyl, carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z7 and Z8 each independently represent a group selected from hydroxy, nitro, cyano, C1-C5 alkoxy, formyl and sulfonic acid; m and n are independently integers from 0 to 5, m + n is 5 or less; o and p are independently integers from 0 to 4, o + p is 4 or less.]

[0044] Furthermore, exemplary aromatic acids may have the following general formula (VI).

[0045] [Chemical formula]

[0046] [In the formula, X is O or S; R9 independently represents a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C20 aryl group, or a combination thereof, and optionally contains one or more groups selected from carbonyl, carbonyloxy, sulfonamide, ether, thioether, substituted or unsubstituted alkylene group, or a combination thereof; Z9 independently represents a group selected from carboxyl, hydroxy, nitro, cyano, C1-C5 alkoxy, formyl and sulfonic acid; q and r are independently integers from 0 to 3, q + r is 3 or less.]

[0047] In one or more embodiments, the acid is a free acid having a fluorine substitution. Suitable free acids having a fluorine substitution can be aromatic or non-aromatic. For example, free acids having a fluorine substitution that can be used as solubility modifiers include, but are not limited to, the following.

[0048] [Chemical formula] [Chemistry]

[0049] [Chemistry] [Chemistry] [Chemistry]

[0050] Suitable TAGs include those capable of generating a non-polymerizable acid as described above. The TAG can be non-ionic or ionic. Suitable non-ionic thermal acid generators include, for example, cyclohexyl trifluoromethyl sulfonate, methyl trifluoromethyl sulfonate, cyclohexyl p-toluenesulfonate, methyl p-toluenesulfonate, cyclohexyl 2,4,6-triisopropylbenzenesulfonate, nitrobenzyl ester, benzoin tosylate, 2-nitrobenzyl tosylate, tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione, alkyl esters of organic sulfonic acids, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, oxalic acid, phthalic acid, phosphoric acid, camphorsulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid and their salts, and combinations thereof. Suitable ionic thermal acid generators include, for example, triethylamine salts of dodecylbenzenesulfonic acid, triethylamine salts of dodecylbenzene disulfonic acid, ammonium salts of p-toluenesulfonic acid, pyridinium salts of p-toluenesulfonic acid, sulfonates such as carbocyclic aryl and heteroaryl sulfonates, aliphatic sulfonates, and benzene sulfonates. Compounds that generate sulfonic acid upon activation are generally suitable. Preferred thermal acid generators include ammonium p-toluenesulfonate and heteroaryl sulfonates.

[0051] Preferably, in the reaction scheme for generating sulfonic acid as shown below, the TAG is ionic.

[0052]

Chemical formula

[0053] wherein, RSO3 - is a TAG anion, and X + is a TAG cation, preferably an organic cation. The cation can be a nitrogen-containing cation of the following general formula (I).

[0054] (BH) + (I)

[0055] This is the monoprotonated form of the nitrogen-containing base B. Suitable nitrogen-containing bases B include, for example, optionally substituted amines such as ammonia, difluoromethylamine, C1-20 alkylamines, and C3-30 arylamines, nitrogen-containing heteroaromatic bases such as pyridine or substituted pyridines (e.g., 3-fluoropyridine), pyrimidine, and pyrazine, and nitrogen-containing heterocyclic groups such as oxazole, oxazoline, or thiazoline. The aforementioned nitrogen-containing base B can be optionally substituted with one or more groups selected from, for example, alkyl, aryl, halogen atoms (preferably fluorine), cyano, nitro, and alkoxy. Among these, the base B is preferably a heteroaromatic base.

[0056] The base B typically has a pKa of 0 to 5.0, 0 to 4.0, 0 to 3.0, or 1.0 to 3.0. As used herein, terms such as "pKa" are used in accordance with the meaning recognized in the art. That is, pKa is the negative logarithm (to base 10) of the dissociation constant of the conjugate acid (BH) + of the basic moiety (B) in an aqueous solution at approximately room temperature. In certain embodiments, the base B has a boiling point of less than about 170 °C, less than about 160 °C, less than 150 °C, less than 140 °C, less than 130 °C, less than 120 °C, less than 110 °C, less than 100 °C, or less than 90 °C.

[0057] Suitable exemplary nitrogen-containing cations (BH) + include NH4 + CF2HNH2 +, CF3CH2NH3 + , (CH3)3NH + , (C2H5)3NH + , (CH3)2(C2H5)NH + and the following may be mentioned.

[0058] [Chemical formula]

[0059] [In the formula, Y is alkyl, preferably methyl or ethyl]

[0060] In certain embodiments, the solubility modifier can be an acid such as trifluoromethanesulfonic acid, perfluoro-1-butanesulfonic acid, p-toluenesulfonic acid, 4-dodecylbenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid and 2-trifluoromethylbenzenesulfonic acid, an acid generator such as triphenylsulfonium antimonate, pyridinium perfluorobutanesulfonate, 3-fluoropyridinium perfluorobutanesulfonate, 4-t-butylphenyltetramethylenesulfonium perfluoro-1-butanesulfonate, 4-t-butylphenyltetramethylenesulfonium 2-trifluoromethylbenzenesulfonate and 4-t-butylphenyltetramethylenesulfonium 4,4,5,5,6,6-hexafluorodihydro-4H-1,3,2-dithiazine 1,1,3,3-tetraoxide, or a combination thereof.

[0061] Alternatively, when the first photoresist is an NTD photoresist, the solubility modifier may include a base or a base generator. In such embodiments, suitable solubility modifiers include, but are not limited to, hydroxides, carboxylates, amines, imines, amides, and mixtures thereof. Specific examples of bases include ammonium carbonate, ammonium hydroxide, ammonium hydrogen phosphate, ammonium phosphate, tetramethylammonium carbonate, tetramethylammonium hydroxide, tetramethylammonium hydrogen phosphate, tetramethylammonium phosphate, tetraethylammonium carbonate, tetraethylammonium hydroxide, tetraethylammonium hydrogen phosphate, tetraethylammonium phosphate, and combinations thereof. Amines include aliphatic amines, alicyclic amines, aromatic amines, and heterocyclic amines. The amine can be a primary amine, secondary amine, or tertiary amine. The amine can be a monoamine, diamine, or polyamine. Suitable amines can include C1-30 organic amines, imines, or amides, or quaternary ammonium salts of C1-30 strong bases (e.g., hydroxides or alkoxides) or weak bases (e.g., carboxylates). Exemplary bases include amines such as tripropylamine, dodecylamine, tris(2-hydroxypropyl)amine, tetrakis(2-hydroxypropyl)ethylenediamine, arylamines such as diphenylamine, triphenylamine, aminophenol, and 2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, hindered amines such as trager base, diazabicycloundecene (DBU) or diazabicyclononene (DBN), amides such as tert-butyl 1,3-dihydroxy-2-(hydroxymethyl)propane-2-ylcarbamate and tert-butyl 4-hydroxypiperidine-1-carboxylate, or ionic quenchers including quaternary alkylammonium salts such as tetrabutylammonium hydroxide (TBAH) or tetrabutylammonium lactate.In another embodiment, the amine is a hydroxyamine. Examples of hydroxyamines include hydroxyamines having one or more hydroxyalkyl groups each having from 1 to about 8 carbon atoms, preferably from 1 to about 5 carbon atoms (e.g., hydroxymethyl group, hydroxyethyl group, and hydroxybutyl group). Specific examples of hydroxyamines include monoethanolamine, diethanolamine, and triethanolamine, 3-amino-1-propanol, 2-amino-2-methyl-1-propanol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, N-methylethanolamine, 2-diethylamino-2-methyl-1-propanol, and triethanolamine.

[0062] A suitable base generator can be a thermal base generator. The thermal base generator forms a base when heated at a temperature higher than the first temperature, typically at about 140 °C or higher. The thermal base generator can include functional groups such as amides, sulfonamides, imides, imines, O-acyl oximes, benzoyloxycarbonyl derivatives, quaternary ammonium salts, nifedipine, carbamates, and combinations thereof. Exemplary thermal base generators include o-{β-(dimethylamino)ethyl}aminocarbonylbenzoic acid, o-{γ-(dimethylamino)propyl}aminocarbonylbenzoic acid, 2,5-bis{β-(dimethylamino)ethyl}aminocarbonylterephthalic acid, 2,5-bis{γ-(dimethylamino)propyl}aminocarbonylterephthalic acid, 2,4-bis{β-(dimethylamino)ethyl}aminocarbonylisophthalic acid, 2,4-bis{γ-(dimethylamino)propyl}aminocarbonylisophthalic acid, and combinations thereof.

[0063] In one or more embodiments, the solubility modifier includes a solvent. As described above, in some embodiments, the solubility modifier is absorbed into the first relief pattern. Thus, the solvent can be any suitable solvent that can promote absorption into the first relief pattern as long as it does not dissolve the first photoresist. The solvent is typically selected from water, organic solvents, and mixtures thereof. In some embodiments, the solvent can include an organic solvent system including one or more organic solvents. The term "organic-based" means that the solvent system includes more than 50% by weight of an organic solvent based on the total solvent of the solubility modifier composition, and more typically, more than 90% by weight, more than 95% by weight, more than 99% by weight, or 100% by weight of an organic solvent based on the total solvent of the solubility modifier composition. The solvent component is typically present in an amount of 90 to 99% by weight based on the solubility modifier composition.

[0064] Suitable organic solvents for the solubility modifier composition include, for example, alkyl propionates such as n-butyl propionate, n-pentyl propionate, n-hexyl propionate and n-heptyl propionate, and alkyl esters such as alkyl butyrates such as n-butyl butyrate, isobutyl butyrate and isobutyl isobutyrate; ketones such as 2,5-dimethyl-4-hexanone and 2,6-dimethyl-4-heptanone; aliphatic hydrocarbons such as n-heptane, n-nonane, n-octane, n-decane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane and 2,3,4-trimethylpentane, and fluorinated aliphatic hydrocarbons such as perfluoroheptane; linear, branched or cyclic C4-C9 monohydric alcohols such as 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 3-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol and 4-octanol, alcohols such as 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol and 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol, and C5-C9 fluorinated diols such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol, ethers such as isopentyl ether and dipropylene glycol monomethyl ether, and mixtures containing one or more of these solvents.

[0065] The solvent contained in the absorbent material can depend on the composition and tone of the first resist. As is typical for ArF resists, when the first resist is formed from a (meth)acrylate polymer and the resist is developed as a PTD resist, the solvent system preferably includes one or more polar organic solvents. For example, a solubility modifier intended to be absorbed into a PTD first resist can include a polar solvent such as methyl isobutyl carbinol (MIBC). The solubility modifier can also include aliphatic hydrocarbons, esters, and ethers as co-solvents, such as, for example, decane, isobutyl isobutyrate, isoamyl ether, and combinations thereof. In certain embodiments, the solvent includes MIBC and a co-solvent. In such embodiments, MIBC can be contained in the solvent in an amount in the range of 60 to 99% based on the total volume of the solvent. Accordingly, the co-solvent can be contained in an amount in the range of 1 to 40% based on the total volume of the solvent.

[0066] As is typical for KrF and EUV photoresists, when the first resist is formed from an aromatic vinyl-based polymer and the resist is developed as a PTD resist, the solvent system preferably includes one or more nonpolar organic solvents. The term “nonpolar organic system” means that the solvent system includes more than 50 wt% total nonpolar organic solvent based on the total solvent of the solubility modifier composition, and more typically includes more than 70 wt%, more than 85 wt%, or 100 wt% total nonpolar organic solvent based on the total solvent of the solubility modifier composition. The nonpolar organic solvent is typically present in the solvent system in a total amount of 70 to 98 wt%, preferably 80 to 95 wt%, more preferably 85 to 98 wt% based on the solvent system.

[0067] Suitable nonpolar solvents include, for example, ethers, hydrocarbons, and combinations thereof, with ethers being preferred. Suitable ether solvents include, for example, alkyl monoethers and aromatic monoethers, and those having a total carbon number of 6 to 16 are particularly preferred. Suitable alkyl monoethers include, for example, 1,4-cineole, 1,8-cineole, pinene oxide, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, di-n-pentyl ether, diisoamyl ether, dihexyl ether, diheptyl ether, and dioctyl ether, with diisoamyl ether being preferred. Suitable aromatic monoethers include, for example, anisole, ethyl benzyl ether, diphenyl ether, dibenzyl ether, and phenetole, with anisole being preferred. Suitable aliphatic hydrocarbons include, for example, n-heptane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane, 2,3,4-trimethylpentane, n-octane, n-nonane, n-decane, and fluorinated compounds such as perfluoroheptane. Suitable aromatic hydrocarbons include, for example, benzene, toluene, and xylene.

[0068] In some embodiments, the solvent system further comprises one or more alcohol and / or ester solvents. For certain compositions, the alcohol and / or ester solvents can provide improved solubility with respect to the solid components of the composition. Suitable alcohol solvents include, for example, linear, branched, or cyclic C such as 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 3-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, and 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol 4-9A monohydric alcohol, and C such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol 5-9 Fluorinated diols are included. The alcohol solvent is preferably a C 4-9 Monohydric alcohol, and 4-methyl-2-pentanol is preferred. Suitable ester solvents include, for example, alkyl esters having a total carbon number of 4 to 10, such as alkyl propionates such as n-butyl propionate, n-pentyl propionate, n-hexyl propionate, and n-heptyl propionate, and alkyl butyrates such as n-butyl butyrate, isobutyl butyrate, and isobutyl isobutyrate. When one or more alcohol solvents and / or ester solvents are used in the solvent system, they are typically present in a total amount of 2 to 50% by weight, more typically 2 to 30% by weight, based on the solvent system.

[0069] The solvent system can also include one or more additional solvents selected from, for example, ketones such as 2,5-dimethyl-4-hexanone and 2,6-dimethyl-4-heptanone, and polyethers such as dipropylene glycol monomethyl ether and tripropylene glycol monomethyl ether. When such additional solvents are used, they are typically present in a total amount of 1 to 20% by weight based on the solvent system.

[0070] When the first resist is formed from an aromatic vinyl-based polymer, a particularly preferred organic solvent system includes one or more monoether solvents in a total amount of 70 to 98% by weight based on the solvent system, and one or more alcohol solvents and / or ester solvents in a total amount of 2 to 30% by weight based on the solvent system. The solvent system is typically present in the overcoat composition in an amount of 90 to 99% by weight, preferably 95 to 99% by weight, based on the overcoat composition.

[0071] In embodiments where the first resist is an NTD resist, suitable organic solvents include, but are not limited to, n-butyl acetate, 2-heptanone, propylene glycol methyl ether, propylene glycol methyl ether acetate, and combinations thereof.

[0072] In some embodiments, the solubility modifier is coated on the first relief pattern. To suitably coat the first relief pattern, the solubility modifier may include a matrix polymer. Any matrix polymer commonly used in the art may be included in the solubility modifying substance. The matrix polymer must have good solubility in a solvent that does not dissolve the first resist. The matrix polymer may be formed from one or more monomers selected from monomers having ethylenically unsaturated polymerizable double bonds such as, for example, (meth)acrylate monomers such as isopropyl (meth)acrylate and n-butyl (meth)acrylate; aromatic vinyl monomers such as (meth)acrylic acid, styrene, hydroxystyrene, vinyl naphthalene, and acenaphthylene; vinyl alcohol, vinyl chloride; vinyl pyrrolidone; vinyl pyridine; vinyl amine; vinyl acetal; maleic anhydride; maleimide; norbornene; and combinations thereof.

[0073] In some embodiments, the polymer contains one or more functional groups selected from, for example, acid groups such as hydroxy, carboxyl, sulfonic acid and sulfonamide, fluoroalcohols such as silanol, hexafluoroisopropyl alcohol [-C(CF3)2OH], anhydrides, lactones, esters, ethers, allylamines, pyrrolidones, and combinations thereof. The polymer can be a homopolymer or a copolymer having distinct repeating units such as, for example, two, three, four or more repeating units. In one aspect, the repeating units of the polymer are all formed from (meth)acrylate monomers, all formed from aromatic (vinyl) monomers, or all formed from (meth)acrylate monomers and aromatic (vinyl) monomers. When the polymer contains more than one type of repeating unit, it typically takes the form of a random copolymer.

[0074] In certain embodiments, the matrix polymer can be a t-butyl acrylate (TBA) / p-hydroxystyrene (PHS) copolymer, a butyl acrylate (BA) / PHS copolymer, a TBA / methacrylic acid (MAA) copolymer, a BA / MAA copolymer, a PHS / methacrylate (MA) copolymer, and combinations thereof.

[0075] The solubility modifier composition typically contains a single polymer, but optionally can contain one or more additional polymers. The polymer content in the composition depends, for example, on the target thickness of the layer, and when a thicker layer is desired, a higher polymer content is used. The polymer is typically present in the pattern solubility modifier composition in an amount of 80 to 99.9 wt%, more typically 90 to 99 wt%, or 95 to 99 wt% based on the total solids of the solubility modifier composition. The weight average molecular weight (Mw) of the polymer is typically less than 400,000, preferably 3000 to 50,000, more preferably 3000 to 25,000 when measured by GPC relative to a polystyrene standard sample. Typically, the polymer has a polydispersity index (PDI = Mw / Mn) of 3 or less, preferably 2 or less when measured by GPC relative to a polystyrene standard sample.

[0076] Polymers suitable for use in the solubility modifier composition are commercially available and / or can be readily prepared by those skilled in the art. For example, the polymer can be synthesized by dissolving a selected monomer corresponding to the polymer unit in an organic solvent, adding a radical polymerization initiator, and performing thermal polymerization to form the polymer. Examples of suitable organic solvents that can be used for the polymerization of the polymer include, for example, toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, ethyl lactate, and methyl isobutyl carbinol. Examples of suitable polymerization initiators include, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide.

[0077] The solubility modifier containing the matrix polymer can be coated on the first relief pattern according to methods known in the art. Typically, the solubility modifier containing the matrix polymer can be coated on the first relief pattern by spin coating. The solid content of the solubility agent can be adjusted to provide a film of the desired thickness of the solubility modifier on the first relief pattern. For example, the solid content of the solubility modifier solution can be adjusted to provide a desired film thickness based on the specific coating apparatus utilized, the viscosity of the solution, the speed of the coating tool, and the time it can be spun. A typical thickness of the composition is from about 200 Å to about 1500 Å.

[0078] In one or more embodiments, the solubility modifier comprises an active substance (i.e., an acid, an acid generator, a base or a base generator), a solvent, and a matrix polymer as described above. A typical formulation of such a solubility modifier can contain from about 1 to 10 wt% solids and from 90 to 99.9 wt% solvent based on the total weight of the solubility modifier, and the solids contain the active substance and the matrix polymer. Within the solid content, the active substance can be contained in an amount ranging from about 1 to about 5 wt%.

[0079] The solubility modifier can contain additives having various purposes depending on the specific chemical reaction used. In some embodiments, a surfactant can be contained in the solubility modifier. The surfactant can be contained in the solubility modifier to assist in the coating quality, especially when it is necessary to fill the thin gaps between the features of the first photoresist. Suitable surfactants known in the art can be contained in the solubility modifier.

[0080] As described above, in one or more embodiments, the solubility modifier is absorbed into the first relief pattern. Absorption of the solubility modifier into the first relief pattern can be achieved by performing a heat pretreatment such as baking. The bake can be a soft bake. The temperature and time of the soft bake can depend on the characteristics of the first resist and the desired amount of diffusion of the solubility modifier into the first resist. Typically, the soft bake can be performed at a temperature in the range of about 50 to about 150 °C for about 30 seconds to about 90 seconds.

[0081] After diffusion into the first resist, a coating layer that contains no effective solubility modifying substance can remain on the first resist. In one or more embodiments, the coating layer can be removed by rinsing. Rinsing can be achieved by rinsing the coated substrate with a solvent that dissolves the coating layer but does not dissolve the first resist. Rinsing can be performed using a suitable method, for example, by immersing the substrate in a bath filled with the solvent for a certain period of time (immersion method), by raising the solvent onto the substrate surface by the action of surface tension and allowing it to stand for a certain period of time to dissolve the coating layer (paddle method), by spraying the solvent onto the substrate surface (spraying method), or by continuously ejecting the solvent onto a rotating substrate while scanning a solvent ejection nozzle at a constant speed (dynamic dispense method).

[0082] In block 106 of method 100, the second resist is deposited on the substrate. A coated substrate laminated with the first relief pattern 204, the solubility modifier 205, and the second resist 206 is shown in FIG. 2C. The second resist is deposited on the substrate, fills the gaps of the first relief pattern, and comes into contact with the first relief pattern or the solubility modifier. In one or more embodiments, the second resist completely covers the substrate, the first relief pattern, and the solubility modifier. The second resist can be deposited on the substrate according to any suitable method known in the art, such as spin-on deposition or vapor phase treatment.

[0083] In one or more embodiments, the second resist comprises a polymer. Suitable polymers can be as described above with respect to the polymers defined as the first resist polymer and / or the matrix polymer. In certain embodiments, suitable polymers can be made from monomers including p-hydroxystyrene, styrene, t-butyl acrylate, and combinations thereof. In certain embodiments, the polymer can be made from all three of p-hydroxystyrene, styrene, and t-butyl acrylate. Such polymers can be prepared from a polymerization reaction comprising about 50 to about 80% p-hydroxystyrene, about 10 to about 30% styrene, and about 10 to about 30% t-butyl acrylate. For example, the polymerization reaction to produce the polymer contained in the second resist can be an amount of p-hydroxystyrene in the range from a lower limit of one of 50%, 55%, 60%, and 65% to an upper limit of one of 65%, 70%, 75%, and 80%, where any lower limit can be paired with any mathematically compatible upper limit, p-hydroxystyrene, and styrene and t-butyl acrylate in individual amounts in the range from a lower limit of one of 10%, 12%, 14%, 16%, 18%, and 20% to an upper limit of one of 20%, 22%, 24%, 26%, 28%, and 30%, where any lower limit can be paired with any mathematically compatible upper limit.

[0084] The polymer contained in the second resist can have a weight average molecular weight (Mw) in the range of 1 to 100 kg / mol. For example, in one or more embodiments, the second resist can comprise a polymer having an Mw range from a lower limit of one of 1 kg / mol, 2 kg / mol, 5 kg / mol, 10 kg / mol, 15 kg / mol, 20 kg / mol, and 25 kg / mol to an upper limit of one of 25 kg / mol, 50 kg / mol, 75 kg / mol, 80 kg / mol, 90 kg / mol, and 100 kg / mol, where any lower limit can be paired with any mathematically compatible upper limit. Polymers having such Mw can exhibit desirable dissolution characteristics, such as dissolution rate.

[0085] In one or more embodiments, the second resist includes a photoacid generator. The photoacid generator is as described above with respect to the photoacid generator contained in the first resist.

[0086] In one or more embodiments, the second resist includes a solvent. The solvent is as described above with respect to the solvent contained in the solubility modifier. In certain embodiments, the solvent in the second resist is the same as the solvent in the solubility modifier.

[0087] The second resist may include additives having various purposes depending on the specific chemical properties used. In some embodiments, a quencher is included in the second resist. The quencher may be included in the second resist to help control the diffusion of the active substance in the solubility modifier. Suitable quenchers include any of the bases already listed with respect to the solubility modifying substance.

[0088] The second resist can be a PTD resist or an NTD resist. Both the PTD resist and the NTD resist can include a polymer and a solvent as described above. In embodiments where the second resist is an NTD resist, it may also include an acid or a photoacid generator. The acid or photoacid generator is as described above with respect to the solubility modifying substance.

[0089] In block 108 of method 100, the solubility modifier diffuses into the second resist. In one or more embodiments, the diffusion of the solubility modifier into the second resist is achieved by performing a bake. The bake can be performed on a hot plate or in an oven. The temperature and time of the bake can depend on the properties of the second resist and the desired amount of diffusion of the solubility modifier into the second resist. Suitable conditions for the bake can include a temperature in the range of 50°C to 160°C and a time in the range of about 30 to 90 seconds. In one or more embodiments, after the bake, the region where the solubility has changed can be present around the edge of the second resist. The amount of diffusion of the solubility modifier can correspond to the thickness of the region where the solubility has changed. In some embodiments, the region where the solubility has changed extends into the second resist and has a thickness of about 5 to about 60 nm. For example, the thickness of the region where the solubility has changed can range from one of the lower limits of 5 nm, 10 nm, 15 nm, 20 nm, and 25 nm to one of the upper limits of 40 nm, 45 nm, 50 nm, 55 nm, and 60 nm, and any lower limit can be paired with any mathematically compatible upper limit. In one or more embodiments, the thickness of the region where the solubility has changed can correspond to the desired line width that is cut into the substrate.

[0090] A coated substrate including a region where the solubility has changed is shown in FIG. 2D. As shown in FIG. 2D, the coated substrate includes a substrate layer 202. The substrate is as described above. A first relief pattern 204 composed of a first photoresist 203 is on the surface of the substrate 202. The first relief pattern 204 is coated with a solubility modifier. A second resist 208 is coated on the first relief pattern and the substrate. In one or more embodiments, the second resist 208 completely covers the substrate 202 and the first relief pattern 204. The region 206 where the solubility of the second resist has changed is shown in contact with the first relief pattern.

[0091] The regions where the solubility has changed may have different solubilities from the regions of the second resist that were not exposed to the solubility modifier. Thus, the regions where the solubility of the second resist has changed and the unexposed regions may be soluble in different resist developers.

[0092] In block 110 of method 100, the deposited layer of the second resist can be developed using a specific developer, leaving either the regions where the solubility has changed or the unexposed regions of the second resist. In one or more embodiments, the regions where the solubility of the second resist has changed are developed by first exposing them to actinic radiation and then to a specific developer. In other embodiments, the regions where the solubility of the second resist has changed are exposed only to a specific developer. The specific developer may depend on the tone of the second resist. For example, if the second resist is a positive tone developing photoresist, the specific developer may be a base such as tetramethylammonium hydroxide. On the other hand, if the second resist is a negative tone developing resist, the specific developer may be a nonpolar organic solvent such as n-butyl acetate or 2-heptanone.

[0093] As described above, the thickness of the region with changed solubility can correspond to the desired line width to be cut into the substrate. FIG. 2E shows a coated substrate developed according to an embodiment of the present disclosure. In one or more embodiments, the second resist 208 is developed to dissolve the solubility-changing region, which region is between the first relief pattern and the second resist. Thus, by dissolving the region with changed solubility, a trench 210 in which the substrate 202 is exposed can be formed between the first relief pattern 204 and the second resist 208. Therefore, method 100, referring back to FIG. 1, includes etching the exposed portion of the substrate using the first relief pattern and the second resist as a combined etching mask. Such a method can provide narrow line cuts on the substrate. The etching process can be an isotropic or anisotropic etching process using any suitable dry etching agent such as CF, O, HBr, or F. In one embodiment, the etching agent can be a dry etching agent such as CF, O, HBr, and F.

[0094] Method 100 represents one executable embodiment but is not intended to limit the invention of the present invention. As will be understood by those skilled in the art, the present invention can include various alternative methods, for example, a method in which a solubility modifier diffuses into a region of the first resist rather than the second resist to change its solubility. In such alternative embodiments, the components and techniques used in the method can be as described above with respect to method 100.

[0095] In one or more embodiments, the solubility modifier diffuses into the first resist. In such embodiments, the method may include first forming a first relief pattern in the first resist and then coating the first resist with the solubility modifier. Here, the solubility modifier may diffuse a predetermined distance into the first resist to provide a region where the solubility of the first resist has changed. FIG. 2F shows a coated substrate including a first resist 203 having a region 206 where the solubility has changed. The diffusion of the solubility modifier can occur at different times in such a method and can diffuse into different components, but the diffusion of the solubility modifier can be carried out as described above in method 100. After the solubility modifier has diffused into the first resist, the second resist may be deposited on the substrate. FIG. 2G shows a first resist 203 including a region 206 where the solubility has changed on a substrate coated with a second resist 208. The substrate may then be developed and etched as described with respect to method 100, where in this case the region where the solubility of the first resist has changed is soluble in a particular developer.

[0096] In one or more embodiments, the method may include forming a plurality of narrow line cuts on the substrate. Such a method may include components such as a first resist, a solubility modifier, and a second resist, and processing steps such as coating, diffusion, and development. As will be understood by those skilled in the art, such components and processing steps may be as described above with respect to method 100.

[0097] On the one hand, FIGS. 3A - 3L show schematic diagrams of exemplary methods for cutting a plurality of narrow lines using backbone technology. In FIGS. 3A and 3G, the pattern of line 405 is formed on substrate 404. The line can be formed from a hard mask material and can be formed by methods generally known in the art. Suitable hard mask materials are known in the art and include, for example, silicon oxide, silicon nitride, silicon oxynitride, tungsten, titanium, titanium nitride, titanium oxide, zirconium oxide, aluminum oxide, aluminum oxynitride, hafnium oxide, and SOC. Next, as shown in FIGS. 3B and 3H, a lithography process is performed to define a cut pattern 406 using a first resist. As shown in FIGS. 3C and 3I, the photoresist cut pattern 406 is then treated with a solubility modifier that diffuses a predetermined distance into the first resist, providing a region 407 with changed solubility.

[0098] A second resist 408 is then coated on the substrate in FIGS. 3D and 3J. The substrate is then developed to remove the region 407 with changed solubility, as a result of which a part of the pattern of the hard mask line 405 and the substrate 404 are exposed in FIGS. 3E and 3K. The exposed portion of the line pattern is etched to form a new pattern of the modified line 405' in FIGS. 3F and 3L.

[0099] In one or more embodiments, an anti-spacer-on-anti-spacer process may be performed. In such a process, the method may perform the steps of method 100 one or more times. For example, in FIGS. 4A-4G, the anti-spacer-on-anti-spacer process is illustrated by schematic diagrams of the coated substrate at each step of such a process. As shown by the coated substrate of FIG. 4A, the anti-spacer-on-anti-spacer process may first include providing a series of anti-spacers on the substrate according to an anti-spacer process such as method 100. Next, a second solubility modifier is coated onto the anti-spacer pattern to provide the coated substrate of FIG. 4B. The second solubility modifier may be as described above with respect to the solubility modifier of method 100. In FIG. 4C, the second solubility modification is absorbed into the first and second resists that make up the anti-spacer pattern, and then the coating is removed to provide the coated substrate of FIG. 4D. Next, FIG. 4E shows a coated substrate that includes a third resist coated onto the anti-spacer pattern. The third resist may include a polymer as described above. Next, the second solubility modifier is diffused into the third resist. The diffusion of the third resist may be performed by baking such as the soft bake described above. After diffusing the second solubility modifier into the third resist, the third resist includes regions of changed solubility around the edges of the first and second resists, as shown in FIG. 4F. Finally, the third resist is developed, and the regions of changed solubility of the third resist are dissolved, providing trenches in which the substrate is exposed, as shown in FIG. 4G. Thus, FIGS. 4A-4G demonstrate one embodiment of an anti-spacer-on-anti-spacer patterning process.

[0100] Alternatively, in an anti-spacer-on-anti-spacer process, for a single anti-spacer patterning process as described above, the second solubility modifier can diffuse into the first and second resists of the initial anti-spacer pattern, rather than into the third resist. In such an embodiment, the second solubility modifier is deposited on the first and second resists that make up the anti-spacer pattern and then diffuses into the first and second resists to provide regions of changed solubility around the edges of the pattern. The third resist is then deposited on the anti-spacer pattern, and the method can be processed as described above. As will be understood by those skilled in the art, the steps that are duplicated for each method can be carried out as described above.

[0101] In one or more embodiments, the fine lines are cut according to a non-self-aligning resist for lithography technology. In such an embodiment, the lines are defined by lithography and the substrate can be planarized. As a result, all gaps between the lines defined by lithography are filled with another material to make the surface flat, and the cut pattern can be defined by lithography. The narrow lines can then be cut according to the above method.

[0102] Therefore, in one or more embodiments, to fabricate an effective semiconductor device, different segments are separated from each other, but endless lines tend not to be useful. To separate the lines, the lines are first generated as long lines. Typically this is beneficial for processing and then cut into useful segments. In the processing of a semiconductor substrate, the generation (patterning) of a pattern in a target layer can include one or more steps. First, several transfer layers are defined. The pattern is then defined on the substrate by lithography. This is then transferred to the intermediate layer using directional etching.

[0103] In one or more embodiments, a second resist layer (“cut mask”) is formed on top to perform the cut. The cut width can have two functions. As a first function, it sets the separation distance between features, which is desirable for functionality and long-term reliability. As a second function, any additional area is a “waste” that extends the feature without adding benefit. The desired objective regarding forming the cut layer is to have a minimum width that exceeds the dielectric breakdown limit (about 2 - 30 nm depending on the feature) and to minimize the extra extended portion.

[0104] In one or more embodiments, the width of the narrow line cut according to the present disclosure can be controlled by creating an etching mask using specific chemical techniques and principles. Thus, the lines can be placed by lithography, i.e., using lithography techniques such as an etching mask, but the disclosed method can be implemented without a lithography scanner. Furthermore, the lines can be cut directly into the substrate, thus eliminating the need for intermediate spacers or hard mask patterns and reducing costs.

Claims

1. A method for patterning a substrate, comprising: providing a first relief pattern on the substrate, wherein the first relief pattern includes a first resist; coating the first relief pattern with a solubility modifier; depositing a second resist on the first relief pattern such that the second resist is in contact with the first relief pattern; diffusing the solubility modifier into the second resist by a predetermined distance in the range of 5 to 60 nm to provide a region where the solubility of the second resist is changed, wherein the region where the solubility of the second resist is changed is adjacent to the first relief pattern; developing the second resist such that the region where the solubility is changed is dissolved, thereby providing a gap in which a part of the substrate is exposed between the first relief pattern and the second resist; etching the substrate using the first relief pattern and the second resist as a combined etching mask; and the solubility modifier includes an acid generator selected from the group consisting of pyridinium perfluorobutanesulfonate, 3-fluoropyridinium perfluorobutanesulfonate, 4-t-butylphenyltetramethylenesulfonium perfluoro-1-butanesulfonate, 4-t-butylphenyltetramethylenesulfonium 2-trifluoromethylbenzenesulfonate, 4-t-butylphenyltetramethylenesulfonium 4,4,5,5,6,6-hexafluorodihydro-4H-1,3,2-dithiazine 1,1,3,3-tetraoxide, triphenylsulfonium antimonate, and combinations thereof. A method.

2. A method for patterning a substrate, comprising: providing a first relief pattern on the substrate, wherein the first relief pattern includes a first resist; coating the first relief pattern with a solubility modifier; depositing a second resist on the first relief pattern such that the second resist is in contact with the first relief pattern; Diffusing the solubility modifier by a predetermined distance in the range of 5 to 60 nm into the first resist to provide a region where the solubility of the first resist is changed, wherein the region where the solubility of the first resist is changed is adjacent to the second resist, and developing the first resist, dissolving the region where the solubility is changed, and providing a gap in which a part of the substrate is exposed between the first relief pattern and the second resist, and etching the substrate using the first relief pattern and the second resist as a combined etching mask, and the solubility modifier includes an acid generator selected from the group consisting of pyridinium perfluorobutanesulfonate, 3-fluoropyridinium perfluorobutanesulfonate, 4-t-butylphenyltetramethylenesulfonium perfluoro-1-butanesulfonate, 4-t-butylphenyltetramethylenesulfonium 2-trifluoromethylbenzenesulfonate, 4-t-butylphenyltetramethylenesulfonium 4,4,5,5,6,6-hexafluorodihydro-4H-1,3,2-dithiazine 1,1,3,3-tetraoxide, triphenylsulfonium antimonate, and combinations thereof, a method.

3. The method according to claim 1 or 2, wherein the first relief pattern includes features separated by gaps between the features, and the features include the first resist.

4. The method according to claim 1 or 2, wherein the second resist fills the gap of the first relief pattern.

5. The method according to claim 1 or 2, wherein etching the substrate includes performing anisotropic etching.

6. Providing the first relief pattern on the substrate includes forming a first pattern of lines on the substrate, depositing a layer of the first resist on the first pattern of lines, exposing the first resist to a pattern of actinic radiation, and developing the first resist so that the first relief pattern is formed on the first pattern of lines, and

7. The method according to claim 1 or 2, wherein the acid generator does not contain fluorine.

8. The method according to claim 1 or 2, wherein the solubility modifier contains an acid.

9. The method according to claim 8, wherein the acid does not contain fluorine.

10. The method according to claim 8, wherein the acid is selected from the group consisting of trifluoromethanesulfonic acid, perfluoro-1-butanesulfonic acid, p-toluenesulfonic acid, 4-dodecylbenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, 2-trifluoromethylbenzenesulfonic acid, and combinations thereof.

11. The method according to claim 1 or 2, wherein the solubility modifier contains a matrix polymer containing a monomer having an ethylenically unsaturated polymerizable double bond, the monomer including (meth)acrylate monomer; (meth)acrylic acid; aromatic vinyl monomers such as styrene, hydroxystyrene, vinylnaphthalene, and acenaphthylene; vinyl alcohol; vinyl chloride; vinyl pyrrolidone; vinyl pyridine; vinylamine; vinyl acetal; maleic anhydride; maleimide; norbornene; and combinations thereof.

12. The method according to claim 1 or 2, wherein the solubility modifier contains a matrix polymer containing a monomer containing one or more functional groups selected from the group consisting of hydroxy, carboxyl, sulfonic acid, sulfonamide, silanol, fluoroalcohol, anhydride, lactone, ester, ether, allylamine, pyrrolidone, and combinations thereof.

13. The method according to claim 1 or 2, further comprising diffusing the solubility modifier into the first relief pattern immediately after coating the first relief pattern with the solubility modifier.

14. The method according to claim 13, wherein diffusing the solubility modifier into the first relief pattern is achieved by performing a bake.

15. The method according to claim 1 or 2, wherein the first resist is a positive tone developing resist and the second resist contains a polymer soluble in a polar solvent.

16. The method according to claim 1 or 2, wherein the first resist is a negative tone developing resist and the second resist contains a polymer soluble in a nonpolar organic solvent.

17. The method according to claim 1 or 2, wherein the solubility modifier contains a solvent.

18. The method according to claim 17, wherein the solvent is selected from the group consisting of methyl isobutyl carbinol (MIBC), decane, isobutyl isobutyrate, isoamyl ether, and combinations thereof.

19. The method according to claim 17, wherein the first resist is insoluble in the solvent.

20. The method according to claim 1 or 2, wherein the first resist comprises a polymer made from monomers selected from the group consisting of styrene, p-hydroxystyrene, acrylate, methacrylate, norbornene, and combinations thereof.

21. The method according to claim 15, wherein the specific developer is a basic developer.

22. The method according to claim 21, wherein the basic developer is tetramethylammonium hydroxide.

23. The method according to claim 16, wherein the specific developer is a nonpolar organic solvent selected from the group consisting of n-butyl acetate (NBA), 2-heptanone, and combinations thereof.

24. The method according to claim 1 or 2, wherein the second resist comprises a polymer made from monomers selected from the group consisting of styrene, p-hydroxystyrene, acrylate, methacrylate, norbornene, and combinations thereof.

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