Patent Application
20150234272
The present invention generally relates to metal oxide nanoparticles, and to photoresist compositions comprising metal oxide nanoparticles. More particularly, the present invention relates to nanoparticles having a Group 4 metal oxide core and an organic acid or carboxylate ligand, to photoresist compositions comprising metal oxide nanoparticles, and to methods of patterning that use the inventive photoresist compositions.
As described by Moore's law, the semiconductor industry drives down pattern dimensions in order to reduce transistor size and enhance processor speed at a rapid pace.
Thus, a need exists for improved materials, including photoresist compositions, that may help to facilitate producing integrated circuit features in the nanoscale/microscale regime.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.
Briefly, the present invention satisfies the need for improved nanoparticles and photoresist compositions, and patterning methods using the compositions. The present invention may address one or more of the problems and deficiencies of the art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In one aspect, the invention provides a nanoparticle comprising:
In another aspect, the invention provides a photoresist composition comprising:
In another aspect, the invention provides a method for patterning a substrate, said method comprising:
Certain embodiments of the presently-disclosed metal oxide nanoparticles, photoresist compositions, and patterning methods have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of these metal oxide nanoparticles and photoresist compositions as defined by the claims that follow, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section of this specification entitled “Detailed Description of the Invention,” one will understand how the features of the various embodiments disclosed herein provide a number of advantages over the current state of the art. These advantages may include, without limitation, providing photoresist compositions and components (e.g., metal oxide nanoparticles) for patternable films that are conducive to pattern formation under ultraviolet exposures (including extreme ultraviolet lithography (EUV)), and/or have one or more improved film parameters, including but not limited to resolution, line edge roughness, and sensitivity.
These and other features and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the appended claims and the accompanying drawings.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:
Aspects of the present invention and certain features, advantages, and details thereof, are explained more fully below, and references are made to the non-limiting embodiments illustrated in the accompanying drawings (which are not necessarily drawn to scale). Descriptions of well-known materials, fabrication tools, processing techniques, etc., are omitted so as to not unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, and are not by way of limitation. Various substitutions, modifications, additions and/or arrangements within the spirit and/or scope of the underlying inventive concepts will be apparent to those skilled in the art from this disclosure.
As used herein, the following definitions shall apply unless otherwise indicated. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75th Ed. Additionally, general principles of organic chemistry are described in “Organic Chemistry”, Thomas Sorrell, University Science Books, Sausalito: 1999, and “March's Advanced Organic Chemistry”, 5th Ed., Ed.: Smith, M. B. and March, J., John Wiley & Sons, New York: 2001.
The term “hydrocarbyl” is a generic term encompassing C1-C10 aliphatic, alicyclic and aromatic groups having an all-carbon backbone, except where otherwise stated. “C.” defines the number (n) of carbon atoms in a group. Examples of hydrocarbyl groups include alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, cycloalkylalkyl, cycloalkenylalkyl, and carbocyclic aralkyl, aralkenyl and aralkynyl groups. Within the sub-set of hydrocarbyl groups are those having 1 to 8 carbon atoms, examples including C1-6 hydrocarbyl groups, such as C1-4 hydrocarbyl groups (e.g., C1-3 hydrocarbyl groups or C1-2 hydrocarbyl groups). Specific examples of hydrocarbyl groups include any individual value or combination of values selected from C1, C2, C3, C4, C5, C6, C7, C8, C9, and C10, hydrocarbyl groups. The groups —CH3, —CH2CH2, —CH(CH3)2, —C(CH3)3, and phenyl are non-limiting examples of specific hydrocarbyl groups. Hydrocarbyl includes any substituent comprised of hydrogen and carbon as the only elemental constituents.
The term “alkyl” covers both straight chain and branched hydrocarbon structures and combinations thereof. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2-methyl butyl, 3-methyl butyl, and n-hexyl and its isomers. Within the sub-set of alkyl groups are those having 1 to 8 carbon atoms, particular examples being C1-6 alkyl groups, such as C1-4 alkyl groups (e.g. C1-3 alkyl groups or C1-2 alkyl groups).
Examples of cycloalkyl groups are those derived from cyclopropane, cyclobutane, cyclopentane, cyclohexane and cycloheptane. Within the sub-set of cycloalkyl groups are cycloalkyl groups having from 3 to 8 carbon atoms, particular examples being C3-6 cycloalkyl groups. Cycloalkyl, if not otherwise limited, refers to monocycles, bicycles and polycycles.
Examples of alkenyl groups include, but are not limited to, ethenyl(vinyl), 1-propenyl, 2-propenyl(allyl), isopropenyl, butenyl, buta-1,4-dienyl, pentenyl, and hexenyl. Within the sub-set of alkenyl groups are those having 2 to 8 carbon atoms, particular examples being C2-6 alkenyl groups, such as C2-4 alkenyl groups.
Examples of cycloalkenyl groups include, but are not limited to, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclopentadienyl and cyclohexenyl. Within the sub-set of cycloalkenyl groups are those having from 3 to 8 carbon atoms, for example, C3-6 cycloalkenyl groups.
Examples of alkynyl groups include, but are not limited to, ethynyl and 2-propynyl (propargyl) groups. Within the sub-set of alkynyl groups are those having 2 to 8 carbon atoms, particular examples being C2-6 alkynyl groups, such as C2-4 alkynyl groups.
Examples of aryl groups, which are defined below, include phenyl and naphthyl groups.
References to “carbocyclic” and “heterocyclic” groups as used herein shall, unless the context indicates otherwise, include both aromatic and non-aromatic ring systems. Thus, for example, the term “carbocyclic and heterocyclic groups” includes within its scope aromatic, non-aromatic, unsaturated, partially saturated and fully saturated carbocyclic and heterocyclic ring systems. In general, such groups may be monocyclic for bicyclic and may contain, for example, 3 to 12 ring members, more usually 5 to 10 ring members. Examples of monocyclic groups are groups containing 3, 4, 5, 6, 7, and 8 ring members, more usually 3 to 7, and preferably 5 or 6 ring members. Examples of bicyclic groups are those containing 8, 9, 10, 11 and 12 ring members, and more usually 9 or 10 ring members.
The term “hydrocarbyloxy” refers to a hydrocarbyl group attached to the parent structure through an oxygen. Examples of hydrocarbyloxy groups include saturated hydrocarbyloxy such as alkoxy (e.g. C1-6 alkoxy, more usually C1-4 alkoxy such as ethoxy and methoxy, particularly methoxy), cycloalkoxy (e.g. C3-6 cycloalkoxy such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy and cyclohexyloxy) and cycloalkyalkoxy (e.g. C3-6 cycloalkyl-C1-2 alkoxy such as cyclopropylmethoxy). Specific non-limiting examples include —OCH3, —OCH2CH3, —O(CH2) 2CH3, —OCH(CH3)2, —13 O(CH2)3CH3, —O(CH2) 4CH3, and phenoxy. For the purpose of this application, alkoxy includes methylenedioxy and ethylenedioxy.
Unless otherwise specified, “acyl” refers to formyl and to groups of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 carbon atoms of a straight, branched, cyclic configuration, saturated, unsaturated and aromatic and combinations thereof, attached to the parent structure through a carbonyl functionality. One or more carbons in the acyl residue may be replaced by nitrogen, oxygen or sulfur as long as the point of attachment to the parent remains at the carbonyl. Examples include acetyl, benzoyl, propionyl, isobutyryl, t-butoxycarbonyl, benzyloxycarbonyl and the like. A subset of acyl is C1-C4 acyl. The double bonded oxygen, when referred to as a substituent itself is called “oxo”. An example of an acyl group is —COCH3.
Unless otherwise specified, “aryl” and “heteroaryl” mean (i) a phenyl group (or benzene) or a monocyclic 5- or 6-membered heteroaromatic ring containing 1-4 heteroatoms independently selected from O, N, and S; (ii) a bicyclic 9- or 10-membered aromatic or heteroaromatic ring system containing 0-4 heteroatoms independently selected from O, N, and S; or (iii) a tricyclic 13- or 14-membered aromatic or heteroaromatic ring system containing 0-5 heteroatoms independently selected from O, N, and S. The aromatic 6- to 14-membered carbocyclic rings include, e.g., benzene, naphthalene, indane, tetralin, and fluorene and the 5- to 10-membered aromatic heterocyclic rings include, e.g., imidazole, pyridine, indole, thiophene, benzopyranone, thiazole, furan, benzimidazole, quinoline, isoquinoline, quinoxaline, pyrimidine, pyrazine, tetrazole and pyrazole. As used herein aryl and heteroaryl refer to residues in which one or more rings are aromatic, but not all need be.
The terms “halohydrocarbyl” and “halohydrocarbyloxy” mean hydrocarbyl or hydrocarbyloxy, respectively, substituted with one or more halogen atoms. Subsets include haloC1-8hydrocarbyl and haloC1-8hydrocarbyloxy, which are groups having 1-8 carbon atoms. Haloalkyl and haloalkoxy are subsets of halohydrocarbyl and halohydrocarbyloxy, respectively. Examples of halohydrocarbyl and halohydrocarbyloxy groups include —CF3 and —OCF3, respectively.
The term “hydrocarbyloxycarbonyl” means a —C(O)hydrocarbyloxy group. An example is —C(O)—O—CH2CH3.
The term “hydrocarbylcarboxy” means a —OC(O)hydrocarbyl group. An example is —OC(O)CH3. C1-8 hydrocarbylcarboxy is a particular subset of hydrocarbylcarboxy.
The term “hydrocarbylthio” means to a hydrocarbyl group attached to a parent structure via a sulfur atom. A subset is C1-8 hydrocarbylthio. Examples of C1-8 hydrocarbylthio groups include —SCH3, —SCH2CH3, and —SCH(CH3)2.
The term “hydrocarbylsulfinyl” means a —SOhydrocarbyl group. A subset is C1-8 hydrocarbylsulfinyl. An example is —SOCH3.
The term “hydrocarbylsulfonyl” means a —SO2hydrocarbyl group. A subset is C1-8 hydrocarbylsulfonyl. An example is —SO2CH3.
The term “acetamide” means a —NHC(O)CH3 group.
The term “aminosulfonyl” means a —SO2NH2 group.
The term “halogen” means fluorine, chlorine, bromine or iodine. In one embodiment, halogen may be fluorine or chlorine.
The term “carboxylate” refers to a dissociated acid. Carboxylates are monovalent anions having the formula RCOO−.
Substituents (e.g. Rn) are generally defined when introduced and retain that definition throughout the specification and in all independent claims.
Although this invention is susceptible to embodiment in many different forms, certain embodiments of the invention are shown and described. It should be understood, however, that the present disclosure is to be considered as an exemplification of the principles of this invention and is not intended to limit the invention to the embodiments illustrated.
In a first aspect, the invention relates to a nanoparticle. The nanoparticle may interchangeably be referred to as a nanoparticle, a metal oxide nanoparticle, or a hybrid metal oxide nanoparticle (on account of its architecture, which includes both core and coating/shell).
The inventive nanoparticles include a core, which comprises a Group 4 metal oxide, and a coating (which may also and interchangeably be referred to as a shell). The coating surrounds the core, and includes one or more ligands selected from an organic acid according to Formula (I):
and a carboxylate thereof, wherein R1, R2, R3, R4, and R5 are each individually selected from hydrogen, C1-8hydrocarbyl, halogen, hydroxyl, acyl, C1-8hydrocarbylcarboxy, C1-8 hydrocarbyloxy, C1-8 hydrocarbyloxycarbonyl, carboxy, haloC1-8hydrocarbyl, C1-8 hydrocarbylthio, mercapto, cyano, thiocyanate, C1-8 hydrocarbylsulfinyl, C1-8 hydrocarbylsulfonyl, aminosulfonyl, amino, nitro, and acetamide, or two adjacent R1-R5 groups, together with the carbon atoms to which they are attached, may form a 4-, 5- or 6-membered carbocyclic ring.
As used herein, when a Cn-n′group (e.g., a Cn-n′ hydrocarbyl group) is recited, whether on its own or as part of another group (e.g., haloCn-n′hydrocarbyl), it is intended that the recitation “C.n-n′” includes all numbers and subranges falling within the n-n′ range. For example, where C1-8 is recited, the recitation is intended to be shorthand, as if C1, C2, C3, C4, C5, C6, C7, and C8 were fully set forth. As further example, the term C1-8 is intended to include all subranges therein, including, for example, C1-6, C1-4, C1-3, C2-6, etc.
Examples of embodiments where two adjacent R1-R5 groups, together with the carbon atoms to which they are attached, form a 4-, 5- or 6-membered carbocyclic ring, include where two R groups, taken together, are —(CH2)2—, —(CH2)3—, or —(CH2) 4—, so as to form, together with the benzoic acid benzene ring, a bicyclic 1,2-dihydrocyclobutabenzene, 2,3-dihydro-1H-indene, or 1,2,3,4-tetrahydronaphthalene core.
In some embodiments where two adjacent R1-R5 groups, together with the carbon atoms to which they are attached, form a 4-, 5- or 6-membered carbocyclic ring, the two adjacent R1-R5 groups are R3 and R4. In some embodiments, the two adjacent R1-R5 groups are R4 and R5. In some embodiments, the two adjacent R1-R5 groups are R2 and R3. In some embodiments, the two adjacent R1-R5 groups are R1 and R2.
In some embodiments, R1, R2, R3, R4, and R5 are each individually selected from H, F, Cl, Br, —OH, —CH3, —CH2CH2, —CH(CH3)2, —C(CH3)3, phenyl, —COCH3, —OC(O)CH3, —OCH3, —OCH2CH3, O(CH2) 2CH3, OCH(CH3)2, —O(CH2)3CH3, —O(CH2) 4CH3, phenoxy, —C(O)-O—CH2CH3, —C(O)OH, —CF3, —OCF3, —SCH3, —SCH2CH3, —SCH(CH3)2, —SH, —CN, —SCN, —SOCH3, —SO2CH3, —SO2NH2, —NH2, —NO2, and —NHC(O)CH3.
In some embodiments, R1, R2, R3, R4, and R5 are individually selected from H, —F, —CH3, —NH2, —OH, —NO2, and —CF3.
In some embodiments, R1, R2, R3, R4, and R5 are all hydrogen.
In some embodiments, the benzene ring in Formula (I) has one non-hydrogen substituent (i.e., one of R1, R2, R3, R4, and R5 is other than hydrogen, and the remaining R1-R5 are hydrogen). In some embodiments, the benzene ring in Formula (I) has one two non-hydrogen substituents. In some embodiments, the benzene ring in Formula (I) has one three non-hydrogen substituents. In some embodiments, the benzene ring in Formula (I) has four non-hydrogen substituents. In some embodiments, all of R1-R5 are other than hydrogen.
In some embodiments, the ligand of Formula (I) or carboxylate thereof may be ortho-, meta-, or para-substituted (i.e., may have non-hydrogen substituents in the ortho, meta, or para positions).
In some embodiments, the ligand is an organic acid of Formula (I). In some embodiments, the ligand is a carboxylate of the organic acid of Formula (I). In some embodiments, the nanoparticle comprises both an organic acid according to Formula (I) and a carboxylate thereof
In some embodiments, the ligand is benzoic acid or a carboxylate thereof. In such embodiments, one or both of the acid and the carboxylate thereof may be present.
The core of the inventive nanoparticle comprises a Group 4 metal oxide. In some embodiments, the core comprises more than one Group 4 metal oxide (e.g., 2 metal oxides, 3 metal oxides, etc.).
The Group 4 metal oxide in the nanoparticle core may comprise titanium (Ti), zirconium (Zr), and/or hafnium (Hf). In some embodiments, the core comprises hafnium oxide (e.g., HfO2). In some embodiments, the core comprises zirconium oxide (e.g., ZrO2). In some embodiments, the core comprises titanium oxide (e.g., TiO2).
In some embodiments, the nanoparticle of the invention has a diameter of about 1 to 12 nm (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 nm), including any and all ranges and subranges therein (e.g., 1-4 nm, 2.5-5 nm, 2-4 nm, etc.)
In some embodiments, the nanoparticle of the invention comprises 35 wt % to 75 wt % (e.g., 35, 40, 45, 50, 55, 60, 65, 70, 75 wt %, etc.) core (i.e., the core constitutes 35-75 wt % of the entire nanoparticle), including any and all ranges and subranges therein. In some embodiments, the nanoparticle comprises 35-75 wt % titanium oxide, zirconium oxide, or hafnium oxide, or combinations thereof
In some embodiments, the nanoparticle of the invention comprises 25 wt % to 65 wt % (e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65 wt %, etc.) coating (i.e., the coating constitutes 35-75 wt % of the entire nanoparticle), including any and all ranges and subranges therein. In some embodiments, the nanoparticle comprises 25-65 wt % organic ligand.
In some embodiments, the inventive nanoparticle comprises TiO2, ZrO2, or HfO2 (meaning at least one of the oxides) and the ligand is benzoic acid or a carboxylate thereof
In some embodiments, the invention provides a photoresist composition that comprises the nanoparticle according to claim 1.
In some embodiments, the invention provides a photoresist film (e.g., a film that has been deposited by, for example, spin-coating) that comprises the nanoparticle according to claim 1.
In some embodiments, the invention provides photoresist compositions and photoresist films that comprise a nanoparticle according to claim 1 and a photoacid generator. Photoacid generators are discussed below. In some embodiments, the photoacid generator is selected from N-hydroxynaphthalimide triflate, triphenylsulphonium triflate, and triphenylsulphonium perfluoro-1-butanesulphonate.
In another aspect, the invention relates to a photoresist composition comprising a nanoparticle and a photoacid generator. The nanoparticle comprises a core, which comprises a Group 4 metal oxide, and a coating surrounding the core. The coating comprises a ligand selected from an acid and a carboxylate of the acid. The photoacid generator is one that is capable, upon photodecomposition, of generating an acid having a pKa lower than the pKa of the ligand acid.
As used herein, “pKa of the ligand acid” (pKaLA) refers to the pKa of the ligand acid (if the nanoparticle coating comprises a ligand that is an acid), or to the pKa of the acid form of the carboxylate ligand (if the nanoparticle coating comprises a ligand that is a carboxylate). For example, if the nanoparticle coating comprises, as a ligand, RCOO−, then “pKa of the ligand acid,” or “pKaLA,” would refer to the pKa of the corresponding acid, RCOOH, and the photoacid generator in the photoresist composition would be capable of generating an acid having a pKa lower than the pKa of RCOOH. Thus, the pKaLA for an acid and a carboxylate thereof, RCOOH and RCOO−, respectively, is the same.
A photoacid generator is a compound that can be decomposed by light or radiation to generate an acid. Various photoacid generators are known in the art, and may be used in the inventive photoresist compositions, provided that the pKa of the acid that the photoacid generator is capable of generating (pKaPAG) is lower than the pKa of the ligand acid (pKaLA).
Where more than one ligand is present in the nanoparticle coating (other than the situation where two ligands are present, one being an acid and the other being a carboxylate of that acid), the photoacid generator is capable of generating an acid having a pKa (pKaPAG) that is lower than at least the highestlowest pKaPAG. In some embodiments, where more than one ligand is present in the nanoparticle coating, the photoacid generator is capable of generating an acid having a pKa (pKaPAG) that is lower than all of the pKa's of the ligand acids.
In some embodiments, the photoacid generator is ionic. In some embodiments, the photoacid generator is non-ionic.
In some embodiments, the amount of photoacid generator in the photoresist composition is 0.5 to 10 wt % photoacid generator per gram of nanoparticle (e.g., 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt %, including any and all ranges and subranges therein (e.g., 0.5 to 8 wt %, 1 to 7 wt %, etc.).
Examples of photoacid generators that may be used in the invention include, without limitation, Bis(4-tert-butylphenyl)iodonium perfluoro-1-butanesulfonate, Bis(4-tert-butylphenyl)iodonium p-toluenesulfonate, Bis(4-tert-butylphenyl)iodonium triflate, Boc-methoxyphenyldiphenylsulfonium triflate, (4-Bromophenyl)diphenylsulfonium triflate, (tert-Butoxycarbonylmethoxynaphthyl)-diphenylsulfonium triflate, (4-tert-Butylphenyl)diphenylsulfonium triflate, Diphenyliodonium hexafluorophosphate, Diphenyliodonium nitrate, Diphenyliodonium perfluoro-1-butanesulfonate, Diphenyliodonium p-toluenesulfonate, Diphenyliodonium triflate, (4-Fluorophenyl)diphenylsulfonium triflate, N-Hydroxynaphthalimide triflate, N-Hydroxy-5-norbornene-2,3-dicarboximide perfluoro-1-butanesulfonate, (4-Iodophenyl)diphenylsulfonium triflate, (4-Methoxyphenyl)diphenylsulfonium triflate, 2-(4-Methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, (4-Methylphenyl)diphenylsulfonium triflate, (4-Methylthiophenyl)methyl phenyl sulfonium triflate, (4-Phenoxyphenyl)diphenylsulfonium triflate, (4-Phenylthiophenyl)diphenylsulfonium triflate, Triarylsulfonium hexafluorophosphate salts, Triphenylsulfonium perfluoro-1-butanesufonate, Triphenylsulfonium triflate, Tris(4-tert-butylphenyl)sulfonium perfluoro-1-butanesulfonate, and Tris(4-tert-butylphenyl)sulfonium triflate.
In some embodiments the photoacid generator is selected from N-hydroxynaphthalimide triflate (also known as 1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl trifluoroMethanesulfonate), triphenylsulphonium triflate, and triphenylsulphonium perfluoro-1-butanesulphonate.
The photoresist compositions of the present invention include a nanoparticle that comprises: a core comprising a Group 4 metal oxide; and a coating surrounding the core, said coating comprising a ligand selected from an acid and a carboxylate thereof
Methods for making nanoparticles are known in art, and are described, for example, in U.S. Pat. No. 8,124,230.
The core of the nanoparticle of the inventive photoresist composition may be any core as described above in connection with the inventive nanoparticle.
The ligand acid or carboxylate thereof in the nanoparticle coating surrounding the core may be any acid or carboxylate thereof, provided that pKaLA>pKaPAG.
Certain non-limiting ligands that may be used in the nanoparticles of the inventive photoresist composition can be found, for example, in U.S. Pat. No. 8,124,230.
In some embodiments, the photoresist composition comprises a nanoparticle having a coating that comprises a ligand selected from an organic acid according to Formula (I):
and a carboxylate thereof,
In some embodiments, the inventive photoresist composition comprises the inventive nanoparticle described in the first aspect of the present invention.
In some embodiments, the photoresist composition comprises an organic solvent. In some embodiments, the organic solvent may be propylene glycol monomethyl ether acetate (PGMEA).
In some embodiments, the invention provides a photoresist composition comprising a nanoparticle that includes a coating having a ligand selected from benzoic acid or a carboxylate thereof, methacrylic acid or a carboxylate thereof, or trans-2,3 dimethylacrylic acid or a carboxylate thereof
In some embodiments, the invention provides a photoresist composition comprising a nanoparticle that includes a coating having a ligand selected from methacrylic acid, trans-2,3-dimethylacrylic acid, ethylacrylic acid, propylacrylic acid and methylbutyric acid, and carboxylates thereof (i.e., carboxylates of any of the listed acids).
In some embodiments, the inventive photoresist composition is one that, upon being applied to a substrate, results in a photoresist film that can be patterning using EUV.
In some embodiments, the inventive photoresist composition is one that, upon being applied (e.g., spin-coated) to a substrate, results in a photoresist film capable of producing high resolution (e.g., 22-50 nm lines-space), and smooth patterns (LER ranging from 3-5 nm) under EUV exposures at comparatively lower doses (e.g., 0.8 mJ/cm2 to 17.5 mJ/cm2).
In some embodiments, the inventive photoresist composition is one that, upon being applied to a substrate, results in a photoresist film that is capable of dual-tone patterning (i.e., the resist can be used in positive or negative tone development). Positive and negative tone development techniques suitable for use in patterning a photoresist made from the inventive photoresist composition are well known in the art.
In some embodiments, the photoresist compositions of the invention do not include a photoradical initiator.
In some embodiments, the photoresist compositions of the invention do not include a polymer that is sensitive to the photoacid generator (i.e., do not include a polymer that is sensitive to the acid that the photoacid generator is capable of generating).
In another aspect, the invention provides a method for patterning a substrate, said method comprising:
In some embodiments, patterning methods applied to resists made from the inventive photoresist composition do not include an additional post exposure bake (PEB) to, for example, generate negative tone patterns.
The invention will now be illustrated, but not limited, by reference to specific embodiments described in the following examples.
Synthesis of an Embodiment of the Inventive Nanoparticle —HfO2 Core with Benzoate Ligand Coating:
Hafnium isopropoxide, benzoic acid and PGMEA were purchased from Sigma Aldrich. Solvents like THF and acetone were obtained from Fisher Scientific. A typical synthesis consists of reacting 3g of hafnium isopropoxide and 5g of benzoic acid dissolved in 20m1 of THF respectively. The reactants were stirred at 65° C. for 2 hours followed by addition of 2 ml of DI water, to initiate sol-gel reaction. After 18 hours of reaction time, the reaction mixture was precipitated and washed with a mixture of acetone/water (1:4, vol) and the nanoparticles were dried for 24 hours under vacuum.
The mild reaction conditions of sol-gel chemistry allowed for efficient incorporation of the organic moieties into the inorganic components. HfO2-benzoate nanoparticles were isolated as white amorphous powders as confirmed from x-ray diffraction.
Nanoparticle characterization was done using zetasizer Nano-ZS, Q500 thermogravimetric analyzer, Nicolet iS10 spectrophotometer and SSX-100 XPS. The nanoparticle resists were subjected to UV exposure using the ABM contact aligner and a 300C DUV stepper at Cornell University, and an MET EUV exposure tool at LBNL. SEM images were obtained with the Zeiss Supra SEM at an accelerating voltage ranging from 0.5kV to lkV and 20 gm aperture.
The nanoparticles were easily dispersed in organic solvents like propylene glycol monomethyl ether acetate (PGMEA) at high loadings up to 50% (w/w).
Nanoparticle particle size was determined by dynamic light scattering techniques (
Formation and Deposition of an Embodiment of the Inventive Photoresist:
A photoresist composition was prepared by dispersing HfO2-benzoate nanoparticles in PGMEA at 5-10 wt % of the final dispersion and adding a small amount (1-7 wt % per gram of nanoparticle) of a photoacid generator, N-hydroxynaphthalimide triflate. The hybrid nanoparticles were spin coated on bare silicon wafers using standard protocols as described in Krysak et al., Development of an inorganic nanoparticle photoresist for EUV, e-beam, and 193 nm lithography, Proceedings of SPIE 7972, (Pt. 1, Advances in Resist Materials and Processing Technology XXVIII), 2011, 7972, 79721C1-C6, and Trikeriotis et al., Development of an inorganic photoresist for DUV, EUV, and electron beam imaging, Proceedings of SPIE 7639, (Pt. 1, Advances in Resist Materials and Processing Technology XXVII), 2010, 7639, 76390E1-E10, forming uniform films without any crystalline domains (see
Nano-scale patterning ability of the HfO2-benzoate film was examined under deep ultraviolet (DUV) exposures using a 300C ASML stepper operating at 248 nm.
Patterning an Embodiment of the Inventive Photoresist
According to Moore's Law, the number of transistors that can be packed into an integrated circuit approximately doubles every two years, which stresses the importance of producing high resolution features in order to shrink down transistor dimensions. A significant improvement in the resolution of a patterned image can be obtained by reducing the wavelength of exposed radiation. As a result, higher resolution patterning of a HfO2-benzoate photoresist composition was investigated under extreme ultraviolet (EUV) radiation (λ=13.5 nm) at the Center of X-Ray Optics, LBNL, to probe into sub-50 nm features.
Another notable aspect is that use of the HfO2-benzoate photoacid generator-containing photoresist composition results in films/resists that produce very smooth patterns with line edge roughness (LER) ranging between 3-5 nm. Another study on metal oxide sulphate resists (Stowers et al., Directly patterned inorganic hardmask for EUV lithography. Proc. of SPIE, 2011; Vol. 7969) have produced 26 nm half pitch features at comparable LER values but at a EUV sensitivity >54 mJ/cm2, which is 3 times lower than the HfO2-benzoate nanoparticle resist made with the photoresist composition according to the present invention. Another extensive study on commercial polymeric resists (Wallow et al., Evaluation of EUV resist materials for use at the 32 nm half-pitch node—art. no. 69211F., Emerging Lithographic Technologies Xii, Pts 1 and 2, 2008; Vol. 6921, pp F9211-F9211) with different line-space patterns have shown that at comparable LER, the resolution is restricted to 25 nm lines with an EUV dose to pattern ranging from 30-50 mJ/cm2. From another study (Petrillo et al., Are extreme ultraviolet resists ready for the 32 nm node? J. Vac. Sci. Technol. B, 2007, 25, (6), 2490-2495) on a wide range of ArF and KrF based commercially obtained DUV photoresists it was observed that at comparable resist sensitivity, the resolution was limited to 35 nm lines at comparable LER.
Additional Patterning Testing
Additional testing was performed on various embodiments of the inventive nanoparticles, photoresist compositions, and resists made from the inventive photoresist compositions.
Patterning Counterexample
As an additional confirmation for the ligand displacement mechanism described above, EUV exposure studies were performed with HfO2-benzoate films in the presence of compound 2 (
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”), and “contain” (and any form contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a method or device that “comprises”, “has”, “includes” or “contains” one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements. Likewise, a step of a method or an element of a device that “comprises”, “has”, “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features. Furthermore, a device or structure that is configured in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
As used herein, the terms “comprising” and “including” or grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. This term encompasses the terms “consisting of” and “consisting essentially of”.
The phrase “consisting essentially of” or grammatical variants thereof when used herein are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof but only if the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed composition, device or method.
All publications cited in this specification are herein incorporated by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein as though fully set forth.
Subject matter incorporated by reference is not considered to be an alternative to any claim limitations, unless otherwise explicitly indicated.
Where one or more ranges are referred to throughout this specification, each range is intended to be a shorthand format for presenting information, where the range is understood to encompass each discrete point within the range as if the same were fully set forth herein.
While several aspects and embodiments of the present invention have been described and depicted herein, alternative aspects and embodiments may be affected by those skilled in the art to accomplish the same objectives. Accordingly, this disclosure and the appended claims are intended to cover all such further and alternative aspects and embodiments as fall within the true spirit and scope of the invention.
