Patent Application
20070298349
The present invention relates to a novel antireflective coating composition for forming an underlayer for a photoresist, comprising an acid generator and a novel siloxane polymer, where the siloxane polymer comprises at least one absorbing chromophore and at least one crosslinking group of structure (1),
where m is 0 or 1, W and W′ are independently a valence bond or a connecting group linking the cyclic ether to the silicon of the polymer and L is selected from hydrogen, W′ and W, or L and W′ are combined to comprise a cycloaliphatic linking group linking the cyclic ether to the silicon of the polymer. The functional group of structure (1) is capable of self-crosslinking with other similar groups to form a crosslinked polymer. The invention also relates to a process for imaging the photoresist coated over the novel antireflective coating composition and provides good lithographic results. The invention further relates to a novel siloxane polymer, where the siloxane polymer comprises at least one absorbing chromophore and at least one crosslinking functionality of structure (1), which is capable of self-crosslinking with other similar groups to form a crosslinked polymer. In one embodiment the self-crosslinking functionality of the siloxane polymer is cyclic ether, such as an epoxide or an oxetane. The chromophore in the siloxane polymer can be an aromatic functionality. The novel absorbing polymer is capable of self-crosslinking in the presence of an acid. The antireflective coating composition is useful for imaging photoresists that are sensitive to wavelength of radiation ranging from about 300 nm to about 100 nm, such as 193 nm and 157 nm.
The antireflective coating composition of the present invention comprises a siloxane polymer and an acid generator. The siloxane polymer comprises an absorbing chromophore and a crosslinking functionality of structure (1). The siloxane polymer comprising the functionality of structure (1) is capable of self-crosslinkng in the presence of an acid and so an external crosslinking compound is not required; in fact, small molecular compounds such as crosslinking agents and dyes (absorbing chromophores) can be volatilized during the processing steps and can leave residues or diffuse to an adjacent layer, and are thus less desirable. In one embodiment the novel composition is free of crosslinking agent and/or dye. A siloxane or organosiloxane polymer contains SiO units within the polymer structure, where the SiO units may be within the polymer backbone and/or pendant from the polymer backbone. Siloxane polymers known in the art may be used. Various types of siloxane polymers are known in the art and are exemplified in the following references which are incorporated herein by reference, WO 2004/113417, U.S. Pat. No. 6,069,259, U.S. Pat. No. 6,420,088, U.S. Pat. No. 6,515,073, US 2005277058 and JP 2005-221534. Examples of siloxane polymers, without limitation, are linear polymers and ladder or network (silsesquioxane) types of polymers or polymers comprising mixtures of linear and network blocks. Polyhedral structures of siloxanes are also known and are part of the invention.
In one embodiment the present siloxane polymer comprises units described by (i) and (ii),
(R1SiO3/2) and (R2SiO3/2) (i),
(R′(R″)SiOx) (ii),
where R1 is independently a moiety comprising a crosslinking group, R2 is independently a moiety comprising a chromophore group, R′ and R″ are independently selected from R1 and R2, and x=½ or 1. Typically R2 is a chromophore group such as an aromatic or aryl moiety. In another embodiment the siloxane polymer comprises linear polymeric units described by (iii) and (iv),
—(A1(R1)SiO)— (iii), and
—((A2)R2SiO)— (iv),
where, R1 and R2 are as above, A1 and A2 are independently hydroxyl, R1 and R2, halide (such as fluoride and chloride), alkyl, OR, OC(O)R, alkylketoxime, unsubstituted aryl and substituted aryl, alkylaryl, alkoxy, acyl and acyloxy, and R is selected from alkyl, unsubstituted aryl and substituted aryl. In yet another embodiment the siloxane polymer contains mixtures of network and linear units, that is, network units comprising (i) and/or (ii) and linear units comprising (iii) and/or (iv). Generally, a polymer comprising predominantly the silsesquioxane or network type of units are preferred, since they provide superior dry etch resistance, but mixtures can also be useful.
The polymer of the antireflective coating composition may further comprise one or more other silicon containing units, such as
—(R3SiO3/2)— (v),
where R3 is independently, hydroxyl, hydrogen, halide (such as fluoride and chloride), alkyl, OC(O)R, alkylketoxime, aryl, alkylaryl, alkoxy, acyl and acyloxy, and R is selected from alkyl, unsubstituted aryl and substituted aryl,
—(SiO4/2)— (vi),
—((A1)A2SiOx) (vii),
where x=½ or 1, A1 and A2 are independently hydroxyl, hydrogen, halide (such as fluoride and chloride), alkyl, OR, OC(O)R, alkylketoxime, aryl, alkoxy, alkylaryl, acyl and acyloxy; and mixtures of these units.
In one embodiment the polymer comprises any number of units (i) to (vii), providing there is an absorbing group and a crosslinking group of structure (1) attached to a siloxane polymer. In another embodiment the polymer comprises units (i) and (v).
One example of the polymer may comprise the structure,
(R1SiO3/2)a(R2SiO3/2)b(R3SiO3/2)c(SiO4/2)d
where, R1 is independently a moiety comprising a crosslinking group of structure 1, R2 is independently a moiety comprising a chromophore group, R3 is independently selected from hydroxyl, hydrogen, halide (such as fluoride and chloride), alkyl, OR, OC(O)R, alkylketoxime, aryl, alkylaryl, alkoxy, acyl and acyloxy; where R is selected from alkyl, unsubstituted aryl and substituted aryl; 0<a<1; 0<b<1; 0≦c<1; 0≦d<1. In one embodiment of the polymer the concentration of the monomeric units are defined by 0.1<a<0.9, 0.05<b<0.75, 0.1<c and/or d<0.8.
The novel siloxane polymer of the present composition comprises a crosslinking group, R1, in particular cyclic ethers which are capable of crosslinking with other cyclic ether groups in the presence of acids, especially strong acids. Cyclic ethers can be exemplified by the structure (1):
where m is 0 or 1, W and W′ are independently a valence bond or a connecting group linking the cyclic ether to the silicon of the polymer and L is selected from hydrogen, W′ and W, or L and W′ are combined to comprise a cycloaliphatic linking group linking the cyclic ether to the silicon of the polymer. Cyclic ethers are capable of self-crosslinking to form a crosslinked polymer. The cyclic ether group is referred to as an epoxide or oxirane when m=0, and referred to as oxetane when m=1. In one embodiment the cyclic ether is an epoxide. The epoxide or oxetane may be connected directly to the silicon of the polymer. Alternatively, the cyclic ether of structure (1) may be attached to the siloxane polymer through one or more connecting group(s), W and W′. Examples of W and W′ are independently a substituted or unsubstituted (C1-C24) aryl group, a substituted or unsubstituted (C1-C20) cycloaliphatic group, a linear or branched (C1-C20) substituted or unsubstituted aliphatic alkylene group, (C1-C20) alkyl ether, (C1-C20) alkyl carboxyl, W′ and L combine to comprise a substituted or unsubstituted (C1-C20) cycloaliphatic group, and mixtures thereof. The cyclic ether may be linked to the silicon of the polymer through a combination of various types of connecting groups, that is an alkylene ether and a cycloaliphatic group, an alkylene carboxyl and a cycloaliphatic group, an alkylene ether and alkylene group, aryl alkylene group, and aryl alkylene ether group. The pendant cyclic ether crosslinking groups attached to the silicon of the polymer are exemplified in
The siloxane polymer also comprises a chromophore group, R2, which is an absorbing group which absorbs the radiation used to expose the photoresist, and such chromophore groups can be exemplified by aromatic functionalities or heteroaromatic functionalities. Further examples of the chromophore are without limitation, a substituted or unsubstituted phenyl group, a substituted or unsubstituted anthracyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted naphthyl group, a sulfone-based compound, benzophenone-based compound, a substituted or an unsubstituted heterocyclic aromatic ring containing heteroatoms selected from oxygen, nitrogen, sulfur; and a mixture thereof. Specifically, the chromophore functionality can be bisphenylsulfone-based compounds, naphthalene or anthracene based compounds having at least one pendant group selected from hydroxy group, carboxyl group, hydroxyalkyl group, alkyl, alkylene, etc. Examples of the chromophore moiety are also given in US 2005/0058929. More specifically the chromophore may be phenyl, benzyl, hydroxyphenyl, 4-methoxyphenyl, 4-acetoxyphenyl, t-butoxyphenyl, t-butylphenyl, alkylphenyl, chloromethylphenyl, bromomethylphenyl, 9-anthracene methylene, 9-anthracene ethylene, 9-anthracene methylene, and their equivalents. In one embodiment a substituted or unsubstituted phenyl group is used.
In one embodiment the crosslinking cyclic ether group and the chromophore may be within one moiety attached to the siloxane polymer backbone, where the siloxane polymer has been described previously. This moiety may be described by the structure (R5SiOx), where R5 is a moiety comprising a self-crosslinking cyclic ether group of structure (1) and an absorbing chromophore, and x=½, 1 or 3/2. In the polymer the aromatic chromophore group may be one described previously with pendant cyclic ether group of structure (1). As examples the pendant group could be cycloaliphatic epoxides or glycidyl epoxides.
The polymers of this invention are polymerized to give a polymer with a weight average molecular weight from about 1,000 to about 500,000, preferably from about 2,000 to about 50,000, more preferably from about 3,000 to about 30,000.
The siloxane polymer has a silicon content of greater than 15 weight %, preferable greater than 20 weight %, and more preferably greater than 30 weight %.
In the above definitions and throughout the present specification, unless otherwise stated the terms used are described below.
Alkyl means linear or branched alkyl having the desirable number of carbon atoms and valence. The alkyl group is generally aliphatic and may be cyclic (cycloaliphatic) or acyclic (i.e. noncyclic). Suitable acyclic groups can be methyl, ethyl, n-or iso-propyl, n-, iso, or tert-butyl, linear or branched pentyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl. Unless otherwise stated, alkyl refers to 1-10 carbon atom moeity. The cyclic alkyl (cycloaliphatic) groups may be mono cyclic or polycyclic. Suitable example of mono-cyclic alkyl groups include unsubstituted or substituted cyclopentyl, cyclohexyl, and cycloheptyl groups. The substituents may be any of the acyclic alkyl groups described herein. Suitable bicyclic alkyl groups include substituted bicycle[2.2.1]heptane, bicyclo[2.2.2]octane, bicyclo[3.2.1]octane, bicyclo[3.2.2]nonane, and bicyclo[3.3.2]decane, and the like. Examples of tricyclic alkyl groups include tricyclo[5.4.0.0.2,9]undecanei, tricyclo[4.2.1.2.7,9]undecane, tricyclo[5.3.2.0.4,9]dodecane, and tricyclo[5.2.1.0.2,6]decane. As mentioned herein the cyclic alkyl groups may have any of the acyclic alkyl groups as substituents.
Alkylene groups are divalent alkyl groups derived from any of the alkyl groups mentioned hereinabove. When referring to alkylene groups, these include an alkylene chain substituted with (C1-C10) alkyl groups in the main carbon chain of the alkylene group. Essentially an alkylene is a divalent hydrocarbon group as the backbone. Accordingly, a divalent acyclic group may be methylene, 1,1- or 1,2-ethylene, 1,1-, 1,2-, or 1,3 propylene, 2,5-dimethyl-2,5-hexene, 2,5-dimethyl-2,5-hex-3-yne, and so on. Similarly, a divalent cyclic alkyl group may be 1,2- or 1,3-cyclopentylene, 1,2-, 1,3-, or 1,4-cyclohexylene, and the like. A divalent tricyclo alkyl groups may be any of the tricyclic alkyl groups mentioned herein above. A particularly useful tricyclic alkyl group in this invention is 4,8-bis(methylene)-tricyclo[5.2.1.0.2,6]decane.
Aryl or aromatic groups contain 6 to 24 carbon atoms including phenyl, tolyl, xylyl, naphthyl, anthracyl, biphenyls, bis-phenyls, tris-phenyls and the like. These aryl groups may further be substituted with any of the appropriate substituents e.g. alkyl, alkoxy, acyl or aryl groups mentioned hereinabove. Similarly, appropriate polyvalent aryl groups as desired may be used in this invention. Representative examples of divalent aryl groups include phenylenes, xylylenes, naphthylenes, biphenylenes, and the like.
Alkoxy means straight or branched chain alkoxy having 1 to 10 carbon atoms, and includes, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonanyloxy, decanyloxy, 4-methylhexyloxy, 2-propylheptyloxy, 2-ethyloctyloxy and phenyloxy.
Aralkyl means aryl groups with attached substituents. The substituents may be any such as alkyl, alkoxy, acyl, etc. Examples of monovalent aralkyl having 7 to 24 carbon atoms include phenylmethyl, phenylethyl, diphenylmethyl, 1,1- or 1,2-diphenylethyl, 1,1-, 1,2-, 2,2-, or 1,3-diphenylpropyl, and the like. Appropriate combinations of substituted aralkyl groups as described herein having desirable valence may be used as a polyvalent aralkyl group.
Furthermore, and as used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. Illustrative substituents include, for example, those described hereinabove. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valencies of the heteroatoms. This invention is not intended to be limited in any manner by the permissible substituents of organic compounds.
The novel siloxane polymer may be synthesized as known in the art. Typically the siloxane polymer is made by reacting a compound containing the silicon unit(s) or silane(s), and water in the presence of a hydrolysis catalyst to form the siloxane polymer. The ratio of the various types of substituted and unsubstituted silanes used to form the novel siloxane polymer is varied to provide a polymer with the desirable structure and properties. The silane compound containing the chromophoric unit can vary from about 5 mole % to about 90 mole %, preferably from about 5 mole % to about 75 mole %; the silane compound containing the crosslinking unit can vary from about 5 mole % to about 90 mole %, preferably from about 10 mole % to about 90 mole %. The hydrolysis catalyst can be a base or an acid, exemplified by mineral acid, organic carboxylic acid, organic quaternary ammonium base. Further example of specific catalyst are acetic acid, propionic acid, phosphoric acid, or tetramethylammonium hydroxide. The reaction may be heated at a suitable temperature for a suitable length of time till the reaction is complete. Reaction temperatures can range from about 25° C. to about 170° C. The reaction times can range from about 10 minutes to about 24 hours. Additional organic solvents may be added to solubilize the silane in water, such solvents which are water miscible solvents (e.g. tetrahydrofuran and propyleneglycol monomethylether acetate (PGMEA)) and lower (C1-C5) alcohols, further exemplified by ethanol, isopropanol, 2-ethoxyethanol, and 1-methoxy-2-propanol. The organic solvent can range from 5 weight % to about 90 weight %. Other methods of forming the siloxane polymer may also be used, for example suspension in aqueous solution or emulsion in aqueous solution. The silanes may contain the self-crosslinking functionality and the chromophore in the monomers or may be incorporated into a formed siloxane polymer by reacting it with the compound or compounds containing the functionality or functionalities. The silanes may contain other groups such as halides, hydroxyl, OC(O)R, alkylketoxime, aryl, alkylaryl, alkoxy, acyl and acyloxy; where R is selected from alkyl, unsubstituted aryl and substituted aryl, which are the unreacted substituents of the silane monomer. The novel polymer may contain unreacted and/or hydrolysed residues from the silanes, that is, silicon with end groups such as hydroxyl, hydrogen, halide (e.g. chloride or fluoride), acyloxy, or ORa, where Ra is selected from (C1-C10) alkyl, C(O)Rb, NRb(Rc) and aryl, and Rb and Rc are independently (C1-C10) or aryl. These residues could be of the structure, (XSi(Y)Ox) where X and Y are independently selected from OH, H, OSi—, ORa, where Ra is selected from (C1-C10) alkyl, unsubstituted aryl, substituted aryl, C(O)Rb, NRb(Rc), halide, acyloxy, acyl, oxime, and aryl, and Rb and Rc are independently (C1-C10) or aryl, Y can also be R1 and/or R2 (as described previously), and x=½ or 1.
Silicon-containing antireflective coating materials are typically synthesized from a variety of silane reactants including, for example:
(a) dimethoxysilane, diethoxysilane, dipropoxysilane, diphenyloxysilane, methoxyethoxysilane, methoxypropoxysilane, methoxyphenyloxysilane, ethoxypropoxysilane, ethoxyphenyloxysilane, methyl dimethoxysilane, methyl methoxyethoxysilane, methyl diethoxysilane, methyl methoxypropoxysilane, methyl methoxyphenyloxysilane, ethyl dipropoxysilane, ethyl methoxypropoxysilane, ethyl diphenyloxysilane, propyl dimethoxysilane, propyl methoxyethoxysilane, propyl ethoxypropoxysilane, propyl diethoxysilane, propyl diphenyloxysilane, butyl dimethoxysilane, butyl methoxyethoxysilane, butyl diethoxysilane, butyl ethoxypropoxysilane, butyl dipropoxysilane, butyl methylphenyloxysilane, dimethyl dimethoxysilane, dimethyl methoxyethoxysilane, dimethyl diethoxysilane, dimethyl diphenyloxysilane, dimethyl ethoxypropoxysilane, dimethyl dipropoxysilane, diethyl dimethoxysilane, diethyl methoxypropoxysilane, diethyl diethoxysilane, diethyl ethoxypropoxysilane, dipropyl dimethoxysilane, dipropyl diethoxysilane, dipropyl diphenyloxysilane, dibutyl dimethoxysilane, dibutyl diethoxysilane, dibutyl dipropoxysilane, dibutyl methoxyphenyloxysilane, methyl ethyl dimethoxysilane, methyl ethyl diethoxysilane, methyl ethyl dipropoxysilane, methyl ethyl diphenyloxysilane, methyl propyl dimethoxysilane, methyl propyl diethoxysilane, methyl butyl dimethoxysilane, methyl butyl diethoxysilane, methyl butyl dipropoxysilane, methyl ethyl ethoxypropoxysilane, ethyl propyl dimethoxysilane, ethyl propyl methoxyethoxysilane, dipropyl dimethoxysilane, dipropyl methoxyethoxysilane, propyl butyl dimethoxysilane, propyl butyl diethoxysilane, dibutyl methoxyethoxysilane, dibutyl methoxypropoxysilane, dibutyl ethoxypropoxysilane, trimethoxysilane, triethoxysilane, tripropoxysilane, triphenyloxysilane, dimethoxymonoethoxysilane, diethoxymonomethoxysilane, dipropoxymonomethoxysilane, dipropoxymonoethoxysilane, diphenyloxymonomethoxysilane, diphenyloxymonoethoxysilane, diphenyloxymonopropoxysilane, methoxyethoxypropoxysilane, monopropoxydimethoxysilane, monopropoxydiethoxysilane, monobutoxydimethoxysilane, monophenyloxydiethoxysilane, methyl trimethoxysilane, methyl triethoxysilane, methyl tripropoxysilane, ethyl trimethoxysilane, ethyl tripropoxysilane, ethyl triphenyloxysilane, propyl trimethoxysilane, propyl triethoxysilane, propyl triphenyloxysilane, butyl trimethoxysilane, butyl triethoxysilane, butyl tripropoxysilane, butyl triphenyloxysilane, methyl monomethoxydiethoxysilane, ethyl monomethoxydiethoxysilane, propyl monomethoxydiethoxysilane, butyl monomethoxydiethoxysilane, methyl monomethoxydipropoxysilane, methyl monomethoxydiphenyloxysilane, ethyl monomethoxydipropoxysilane, ethyl monomethoxy diphenyloxysilane, propyl monomethoxydipropoxysilane, propyl monomethoxydiphenyloxysilane, butyl monomethoxy dipropoxysilane, butyl monomethoxydiphenyloxysilane, methyl methoxyethoxypropoxysilane, propyl methoxyethoxy propoxysilane, butyl methoxyethoxypropoxysilane, methyl monomethoxymonoethoxybutoxysilane, ethyl monomethoxymonoethoxy monobutoxysilane, propyl monomethoxymonoethoxy monobutoxysilane, butyl monomethoxymonoethoxy monobutoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenyloxysilane, trimethoxymonoethoxysilane, dimethoxydiethoxysilane, triethoxymonomethoxysilane, trimethoxymonopropoxysilane, monomethoxytributoxysilane, monomethoxytriphenyloxysilane, dimethoxydipropoxysilane, tripropoxymonomethoxysilane, trimethoxymonobutoxysilane, dimethoxydibutoxysilane, triethoxymonopropoxysilane, diethoxydipropoxysilane, tributoxymonopropoxysilane, dimethoxymonoethoxy monobutoxysilane, diethoxymonomethoxy monobutoxysilane, diethoxymonopropoxymonobutoxysilane, dipropoxymonomethoxy monoethoxysilane, dipropoxymonomethoxy monobutoxysilane, dipropoxymonoethoxymonobutoxysilane, dibutoxymonomethoxy monoethoxysilane, dibutoxymonoethoxy monopropoxysilane and monomethoxymonoethoxymonopropoxy monobutoxysilane, and oligomers thereof.
(b) Halosilanes, including chlorosilanes, such as trichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, tetrachlorosilane, dichlorosilane, methyldichlorosilane, dimethyldichlorosilane, chlorotriethoxysilane, chlorotrimethoxysilane, chloromethyltriethoxysilane, chloroethyltriethoxysilane, chlorophenyltriethoxysilane, chloromethyltrimethoxysilane, chloroethyltrimethoxysilane, and chlorophenyltrimethoxysilane are also used as silane reactants. In addition, silanes that can undergo hydrolysis and condensation reactions such as acyloxysilanes, or alkylketoximesilanes, are also used as silane reactants.
(c) Silanes bearing epoxy functionality, include 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-tripropoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-triphenyloxysilane, 2-(3,4-epoxycyclohexyl)ethyl-diethoxymethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-dimethoxyethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-trichlorosilane, 2-(3,4-epoxycyclohexyl)ethyl-triacetoxysilane, (glycidyloxypropyl)-trimethoxysilane, (glycidyloxypropyl)-triethoxysilane, (glycidyloxypropyl)-tripropoxysilane, (glycidyloxypropyl)-triphenyloxysilane, (glycidyloxypropyl)-diethoxymethoxysilane, (glycidyloxypropyl)-dimethoxyethoxysilane, (glycidyloxypropyl)-trichlorosilane, and (glycidyloxypropyl)-triacetoxysilane
(d) Silanes bearing chromophore functionality, include phenyl dimethoxysilane, phenyl methoxyethoxysilane, phenyl diethoxysilane, phenyl methoxypropoxysilane, phenyl methoxyphenyloxysilane, phenyl dipropoxysilane, anthracyl dimethoxysilane, anthracyl diethoxysilane, methyl phenyl dimethoxysilane, methyl phenyl diethoxysilane, methyl phenyl dipropoxysilane, methyl phenyl diphenyloxysilane, ethyl phenyl dimethoxysilane, ethyl phenyl diethoxysilane, methyl anthracyl dimethoxysilane, ethyl anthracyl diethoxysilane, propyl anthracyl dipropoxysilane, methyl phenyl ethoxypropoxysilane, ethyl phenyl methoxyethoxysilane, diphenyl dimethoxysilane, diphenyl methoxyethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane, phenyl tripropoxysilane, anthracyl trimethoxysilane, anthracyl tripropoxysilane, phenyl triphenyloxysilane, phenyl monomethoxydiethoxysilane, anthracyl monomethoxydiethoxysilane, phenyl monomethoxydipropoxysilane, phenyl monomethoxydiphenyloxysilane, anthracyl monomethoxydipropoxysilane, anthracyl monomethoxy diphenyloxysilane, phenyl methoxyethoxypropoxysilane, anthracyl methoxyethoxypropoxysilane, phenyl monomethoxymonoethoxymonobutoxysilane, and anthracyl monomethoxymonoethoxymonobutoxysilane, and oligomers thereof.
Preferred among these compounds are triethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, tetramethoxysilane, methyltrimethoxysilane, trimethoxysilane, dimethyldimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, diphenyldiethoxysilane, diphenyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-triethoxysilane, (glycidyloxypropyl)-trimethoxysilane, (glycidyloxypropyl)-triethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane, and phenyl tripropoxysilane. In another embodiment the preferred monomers are triethoxysilane, tetraethoxysilane, methyltriethoxysilane, tetramethoxysilane, methyltrimethoxysilane, trimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, diphenyldiethoxysilane, and diphenyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-triethoxysilane.
The acid generator of the novel composition is a thermal acid generator capable of generating a strong acid upon heating. The thermal acid generator (TAG) used in the present invention may be any one or more that upon heating generates an acid which can react with the cyclic ether and propagate crosslinking of the polymer present in the invention, particularly preferred is a strong acid such as a sulfonic acid. Preferably, the thermal acid generator is activated at above 90° C. and more preferably at above 120° C., and even more preferably at above 150° C. The photoresist film is heated for a sufficient length of time to react with the coating. Examples of thermal acid generators are metal-free iodonium and sulfonium salts, such as in
The antireflection coating composition of the present invention contains 1 weight % to about 15 weight % of the siloxane polymer, and preferably 4 weight % to about 10 weight % of total solids. The thermal acid generator, may be incorporated in a range from about 0.1 to about 10 weight % by total solids of the antireflective coating composition, preferably from 0.3 to 5 weight % by solids, and more preferably 0.5 to 2.5 weight % by solids.
The solid components of the antireflection coating composition are mixed with a solvent or mixtures of solvents that dissolve the solid components of the antireflective coating. Suitable solvents for the antireflective coating composition may include, for example, a glycol ether derivative such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol dimethyl ether, propylene glycol n-propyl ether, or diethylene glycol dimethyl ether; a glycol ether ester derivative such as ethyl cellosolve acetate, methyl cellosolve acetate, or propylene glycol monomethyl ether acetate; carboxylates such as ethyl acetate, n-butyl acetate and amyl acetate; carboxylates of di-basic acids such as diethyloxylate and diethylmalonate; dicarboxylates of glycols such as ethylene glycol diacetate and propylene glycol diacetate; and hydroxy carboxylates such as methyl lactate, ethyl lactate, ethyl glycolate, and ethyl-3-hydroxy propionate; a ketone ester such as methyl pyruvate or ethyl pyruvate; an alkoxycarboxylic acid ester such as methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 2-hydroxy-2-methylpropionate, or methylethoxypropionate; a ketone derivative such as methyl ethyl ketone, acetyl acetone, cyclopentanone, cyclohexanone or 2-heptanone; a ketone ether derivative such as diacetone alcohol methyl ether; a ketone alcohol derivative such as acetol or diacetone alcohol; lactones such as butyrolactone; an amide derivative such as dimethylacetamide or dimethylformamide, anisole, and mixtures thereof.
The novel composition may further contain a photoacid generator, examples of which without limitation, are onium salts, sulfonate compounds, nitrobenzyl esters, triazines, etc. The preferred photoacid generators are onium salts and sulfonate esters of hydoxyimides, specifically diphenyl iodnium salts, triphenyl sulfonium salts, dialkyl iodonium salts, triakylsulfonium salts, and mixtures thereof.
The antireflective coating composition comprises the polymer, and the thermal acid generator of the instant invention and a suitable solvent or mixtures of solvents. Other components may be added to enhance the performance of the coating, e.g. monomeric dyes, lower alcohols, crosslinking agents, surface leveling agents, adhesion promoters, antifoaming agents, etc.
Since the antireflective film is coated on top of the substrate and is further subjected to dry etching, it is envisioned that the film is of sufficiently low metal ion level and of sufficient purity that the properties of the semiconductor device are not adversely affected. Treatments such as passing a solution of the polymer through an ion exchange column, filtration, and extraction processes can be used to reduce the concentration of metal ions and to reduce particles.
The absorption parameter (k) of the novel composition ranges from about 0.05 to about 1.0, preferably from about 0.1 to about 0.8 as measured using ellipsometry. The refractive index (n) of the antireflective coating is also optimized and can range from 1.3 to about 2.0, preferably 1.5 to about 1.8. The n and k values can be calculated using an ellipsometer, such as the J. A. Woollam WVASE VU-32™ Ellipsometer. The exact values of the optimum ranges for k and n are dependent on the exposure wavelength used and the type of application. Typically for 193 nm the preferred range for k is 0.05 to 0.75, and for 248 nm the preferred range for k is 0.15 to 0.8.
The antireflective coating composition is coated on the substrate using techniques well known to those skilled in the art, such as dipping, spin coating or spraying. The film thickness of the antireflective coating ranges from about 15 nm to about 200 nm. The coating is further heated on a hot plate or convection oven for a sufficient length of time to remove any residual solvent and induce crosslinking, and thus insolubilizing the antireflective coating to prevent intermixing between the antireflective coatings. The preferred range of temperature is from about 90° C. to about 250° C. If the temperature is below 90° C. then insufficient loss of solvent or insufficient amount of crosslinking takes place, and at temperatures above 300° C. the composition may become chemically unstable. A film of photoresist is then coated on top of the uppermost antireflective coating and baked to substantially remove the photoresist solvent. An edge bead remover may be applied after the coating steps to clean the edges of the substrate using processes well known in the art.
The substrates over which the antireflective coatings are formed can be any of those typically used in the semiconductor industry. Suitable substrates include, without limitation, silicon, silicon substrate coated with a metal surface, copper coated silicon wafer, copper, aluminum, polymeric resins, silicon dioxide, metals, doped silicon dioxide, silicon nitride, tantalum, polysilicon, ceramics, aluminum/copper mixtures; gallium arsenide and other such Group III/V compounds. The substrate may comprise any number of layers made from the materials described above.
Photoresists can be any of the types used in the semiconductor industry, provided the photoactive compound in the photoresist and the antireflective coating absorb at the exposure wavelength used for the imaging process.
To date, there are several major deep ultraviolet (uv) exposure technologies that have provided significant advancement in miniaturization, and these radiation of 248 nm, 193 nm, 157 and 13.5 nm. Photoresists for 248 nm have typically been based on substituted polyhydroxystyrene and its copolymers/onium salts, such as those described in U.S. Pat. No. 4,491,628 and U.S. Pat. No. 5,350,660. On the other hand, photoresists for exposure below 200 nm require non-aromatic polymers since aromatics are opaque at this wavelength. U.S. Pat. No. 5,843,624 and U.S. Pat. No. 6,866,984 disclose photoresists useful for 193 nm exposure. Generally, polymers containing alicyclic hydrocarbons are used for photoresists for exposure below 200 nm. Alicyclic hydrocarbons are incorporated into the polymer for many reasons, primarily since they have relatively high carbon to hydrogen ratios which improve etch resistance, they also provide transparency at low wavelengths and they have relatively high glass transition temperatures. U.S. Pat. No. 5,843,624 discloses polymers for photoresist that are obtained by free radical polymerization of maleic anhydride and unsaturated cyclic monomers. Any of the known types of 193 nm photoresists may be used, such as those described in U.S. Pat. No. 6,447,980 and U.S. Pat. No. 6,723,488, and incorporated herein by reference.
Two basic classes of photoresists sensitive at 157 nm, and based on fluorinated polymers with pendant fluoroalcohol groups, are known to be substantially transparent at that wavelength. One class of 157 nm fluoroalcohol photoresists is derived from polymers containing groups such as fluorinated-norbornenes, and are homopolymerized or copolymerized with other transparent monomers such as tetrafluoroethylene (U.S. Pat. No. 6,790,587, and U.S. Pat. No. 6,849,377) using either metal catalyzed or radical polymerization. Generally, these materials give higher absorbencies but have good plasma etch resistance due to their high alicyclic content. More recently, a class of 157 nm fluoroalcohol polymers was described in which the polymer backbone is derived from the cyclopolymerization of an asymmetrical diene such as 1,1,2,3,3-pentafluoro-4-trifluoromethyl-4-hydroxy-1,6-heptadiene (Shun-ichi Kodama et al Advances in Resist Technology and Processing XIX, Proceedings of SPIE Vol. 4690 p76 2002; U.S. Pat. No. 6,818,258) or copolymerization of a fluorodiene with an olefin (WO 01/98834-A1). These materials give acceptable absorbance at 157 nm, but due to their lower alicyclic content as compared to the fluoro-norbornene polymer, have lower plasma etch resistance. These two classes of polymers can often be blended to provide a balance between the high etch resistance of the first polymer type and the high transparency at 157 nm of the second polymer type. Photoresists that absorb extreme ultraviolet radiation (EUV) of 13.5 nm are also useful and are known in the art.
After the coating process, the photoresist is imagewise exposed. The exposure may be done using typical exposure equipment. The exposed photoresist is then developed in an aqueous developer to remove the treated photoresist. The developer is preferably an aqueous alkaline solution comprising, for example, tetramethyl ammonium hydroxide. The developer may further comprise surfactant(s). An optional heating step can be incorporated into the process prior to development and after exposure.
The process of coating and imaging photoresists is well known to those skilled in the art and is optimized for the specific type of resist used. The patterned substrate can then be dry etched with an etching gas or mixture of gases, in a suitable etch chamber to remove the exposed portions of the antireflective film, with the remaining photoresist acting as an etch mask. Various etching gases are known in the art for etching organic antireflective coatings, such as those comprising CF4, CF4/O2, CF4/CHF3, or Cl2/O2.
Each of the documents referred to above are incorporated herein by reference in its entirety, for all purposes. The following specific examples will provide detailed illustrations of the methods of producing and utilizing compositions of the present invention. These examples are not intended, however, to limit or restrict the scope of the invention in any way and should not be construed as providing conditions, parameters or values which must be utilized exclusively in order to practice the present invention.
The refractive index (n) and the absorption (k) values of the antireflective coating in the Examples below were measured on a J. A. Woollam VASE32 ellipsometer.
The molecular weight of the polymers was measured on a Gel Permeation Chromatograph.
A three-neck 500 mL round-bottom flask, equipped with a magnetic stirrer, thermometer and condenser, was charged with 136.1 g of 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane (552 mmol), 68.0 g of phenyltrimethoxysilane (343 mmol), and 136.0 g of methyltrimethoxysilane (1.0 mol). To the flask, was added a mixture of 43.0 g of deionized water (DI) water, 18.0 g of acetic acid, and 127 g of isopropanol. The mixture was heated to reflux and kept at that temperature for 3 hours. Then, the mixture was cooled to room temperature. The solvents were removed under reduced pressure to afford 258.7 g of a colorless liquid polymer. The weight average molecular weight was approximately 7,700 g/mol, determined by gel permeation chromatography using polystyrenes as references.
A three-neck 250 mL round-bottom flask, equipped with a magnetic stirrer, thermometer and condenser, was charged with 35.00 g of 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane (142 mmol), 8.50 g of phenyltrimethoxysilane (43 mmol), and 4.50 g of methyltrimethoxysilane (33 mmol). To the flask, was added a mixture of 5.90 g of DI water, 2.00 g of acetic acid, and 18 g of isopropanol. The mixture was heated to reflux and kept at that temperature for 3 hours. Then, the mixture was cooled to room temperature. The solvents were removed under reduced pressure to afford 41.0 g of a colorless liquid polymer. The weight average molecular weight was approximately 9,570 g/mol, determined by gel permeation chromatography using polystyrenes as references.
A three-neck 250 mL round-bottom flask, equipped with a magnetic stirrer, thermometer and condenser, was charged with 18.40 g of 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane (75 mmol), 15.00 g of phenyltrimethoxysilane (76 mmol), and 46.40 g of tetraethoxysilane (223 mmol). To the flask, was added a mixture of 21.00 g of DI water, 4.00 g of acetic acid, and 82 g of propylene glycol monomethyl ether acetate. The mixture was heated to reflux and kept at that temperature for 3 hours. Then, the mixture was cooled to room temperature. The volatile components were removed under reduced pressure. The weight average molecular weight was approximately 6,900 g/mol, determined by gel permeation chromatography using polystyrenes as references.
A three-neck 250 mL round-bottom flask, equipped with a magnetic stirrer, thermometer and condenser, was charged with 35.0 g of 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane (142 mmol), 8.5 g of phenyltrimethoxysilane (43 mmol), and 4.5 g of triethoxysilane (27 mmol). To the flask, was added a mixture of 5.9 g of deionized water (DI) water, 2.0 g of acetic acid, and 17 g of isopropanol. The mixture was heated to reflux and kept at that temperature for 3 hours. Then, the mixture was cooled to room temperature. The solvents were removed under reduced pressure to afford 41.98 g of a colorless liquid polymer. The weight average molecular weight was approximately 4,490 g/mol, determined by gel permeation chromatography using polystyrenes as references.
A three-neck 100 mL round-bottom flask, equipped with a magnetic stirrer, thermometer and condenser, was charged with 7.56 g of (3-glycidyloxypropyl)trimethoxysilane (32 mmol) and 1.89 g of trimethoxy(2-phenylethyl)silane (8 mmol). To the flask, was added a mixture of 1.09 g of deionized water (DI) water, 0.25 g of acetic acid, and 2.50 g of isopropanol. The mixture was heated to reflux and kept at that temperature for 5 hours. Then, the mixture was cooled to room temperature. The solvents were removed under reduced pressure to afford 4.21 g of a colorless liquid polymer.
3.021 grams of the amine was dissolved in 15 mL of CH2Cl2. This solution was added with cooling to a solution consisting of 5.00 grams of perfluorobutanesulfonic acid dissolved in 10 mL of water. After overnight stirring at room temperature the reaction mixture was stripped of solvents on a rotoevaporator and dried under high vacuum overnight to remove water. In this manner 7.5 grams of a slightly yellowish oil was recovered. The NMR spectra (H1 and C13) were consistent with desired component, and ion chromatography gave a single ionic compound having a retention time of 4.44 minutes. The differential scanning calorimenter (DSC) decomposition temperature of this material was 185° C.
2.753 grams of the amine was dissolved in 15 mL of CH2Cl2. This solution was added with cooling to a solution consisting of 5.00 grams of perfluorobutanesulfonic acid dissolved in 10 mL of water. After overnight stirring at room temperature the reaction mixture was stripped of solvents on a rotoevaporator and dried under high vacuum overnight to remove water. In this manner 4.3 grams of a dark oil was recovered. The NMR spectra (H1 and C13) were consistent with desired component, and ion chromatography gave a single ionic compound having a retention time of 4.8 minutes. The DSC decomposition temperature of this material was 153.5° C.
200 g of the epoxy siloxane polymer prepared in Example 1 and 7.0 g of diphenyliodonium perfluoro-1-butanesulfonate was dissolved in a mixture of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) (70/30 PGMEA/PGME) to achieve 6.3 wt. % of total solids and filtered. This homogeneous solution was spin-coated on a silicon wafer at 1200 rpm. The coated wafer was baked on hotplate at 250° C. for 90 seconds and the film thickness was. Then, n and k values were measured with a VASE Ellipsometer manufactured by J. A. Woollam Co. Inc. The optical constants n and k of the Si-containing film for 193 nm radiation were 1.668 and 0.180 respectively.
2.0 g of the epoxy siloxane polymer prepared in Example 2 and 0.04 g of diphenyliodonium perfluoro-1-butanesulfonate was dissolved in a mixture of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) (70/30 PGMEA/PGME) to achieve 6.2 wt % of total solids and filtered. This homogeneous solution was spin-coated on a silicon wafer at 1200 rpm. The coated wafer was baked on hotplate at 225° C. for 90 seconds. Then, n and k values were measured with a VASE Ellipsometer manufactured by J. A. Woollam Co. Inc. The optical constants n and k of the Si-containing film for 193 nm radiation were 1.728 and 0.209 respectively.
4.90 g of the epoxy siloxane polymer prepared in Example 2 and 0.10 g of N-phenyldiethanolammonium nonaflate from Example 6a was dissolved in a mixture of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) (70/30 PGMEA/PGME) to achieve 5.0 wt. % of total solids. This homogeneous solution was spin-coated on a silicon wafer at 1200 rpm. The coated wafer was baked on hotplate at 250° C. for 90 seconds. Then, n and k values were measured with a VASE Ellipsometer manufactured by J. A. Woollam Co. Inc. The optical constants n and k values of the Si-containing film for 193 nm radiation were 1.721 and 0.155, respectively.
2.0 g of the epoxy polymer prepared in Example 2 and 0.04 g of diphenyliodonium perfluoro-1-butanesulfonate was dissolved in a mixture of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) (70/30 PGMEA/PGME) to achieve 6.2 wt. % of total solids and filtered. This homogeneous solution was spin-coated on a silicon wafer at 1200 rpm. The coated wafer was baked on hotplate at 225° C. for 90 seconds to give a film thickness of 100 nm. Then, a layer of AZ® AX2120 photoresist (available from AZ® Electronic Materials, 70 Meister Avenue, Somerville, N.J.) was spin-coated and baked 100° C. for 60 seconds to give a 190 nm film over the cured antireflective layer. The photoresist was exposed at 193 nm with Nikon 306D and developed for 30 seconds at 23° C. in AZ® 300MIF developer. Lithographic evaluation showed good and clean 80 nm (1:1) line/space pattern with AZ® AX2120 photoresist at 22.5 mJ/cm2 exposure energy.
One substrate coated with composition of Example 10 and another substrate coated with a photoresist AZ1120P (available from AZ Electronic Materials) were etched under conditions in Table I. The etch results were summarized in Table II. The etch rate of Si-containing bottom antireflective coating of the present invention was significantly lower than the photoresist.
