KR20030006956A - Antireflective coating compositions - Google Patents

Abstract

PURPOSE: A coating substrate, an antireflective composition and a forming method of photoresist relief image using the composition are provided, to increase the storage lifetime of solutions of an antireflective composition in a protic medium. CONSTITUTION: The antireflective composition comprises an ionic thermal acid generator compound; and a resin. Preferably the ionic thermal acid generator compound is a sulfonate salt. The coating substrate comprises a layer comprising the antireflective composition; and a photoresist layer formed on the composition layer. Preferably the composition layer comprises further a crosslinker. The forming method comprises the steps of coating the antireflective composition on a substrate; coating a photoresist layer on the composition layer; and exposing and developing the photoresist layer to form a resist relief image.

Description

Antireflective coating compositions

The present invention relates to compositions that reduce back reflection of exposure radiation from a substrate to an overcoated photoresist layer. More specifically, the present invention relates to antireflective coating compositions containing ionic thermal acid generator compounds. Such compositions may exhibit particularly enhanced storage stability.

Photoresist is a photosensitive film used to transfer an image onto a substrate. A coating layer of photoresist is formed on the substrate and then the photoresist layer is exposed to a activating radiation source through a photomask. The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation. Exposure to activating radiation results in photoinduced chemical modification of the photoresist coating, thereby transferring the photomask pattern to the photoresist-coated substrate. After exposure, the photoresist is developed to provide a relief image that allows selective processing of the substrate.

The photoresist may be positive-functional or negative-functional. For most negative-functional photoresists, the portion of the coating layer exposed to activating radiation polymerizes or crosslinks by reaction of the photoactive compound with the polymerizable reagent of the photoresist composition. As a result, the exposed coating portion is less soluble in the developer than the unexposed portion. In the case of positive-functional photoresists, the exposed portions are more soluble in the developer, while the non-exposed areas are relatively less soluble in the developer. Photoresist compositions are described in Deforest, Photoresist Materials and Processes , McGraw Hill Book Company, New York, ch. 2, 1975 and Moreau, Semiconductor Lithography, Principles, Practices and Materials , Plenum Press, New York, ch. 2 and 4 It is described in

Photoresist primarily aims to convert highly polished semiconductor slices, such as silicon or gallium azenide, into composite matrices that perform circuit functions of the electron conduction path, preferably the micron or submicron geometry. It is used for semiconductor manufacturing. The key to achieving this goal is in proper photoresist processing. Although there are strong interdependencies between the various photoresist processing steps, it is believed that one of the most important steps in achieving a high resolution photoresist image is the exposure step.

When the activating radiation used to expose the photoresist is reflected, it often happens that there is a limit to the resolution of the patterned image in the photoresist layer. When the radiation is reflected from the substrate / photoresist interface, there is a spatial variation in the radiation intensity in the photoresist, which may result in uneven line width of the photoresist during development. Irradiation can also be scattered from the substrate / photoresist interface into a photoresist area not intended for exposure treatment, which can also result in a change in line width. The amount of scattering and the amount of reflection typically differ between regions, thus making the line width more non-uniform. Deformation in substrate topography can also cause problems that limit the resolution.

One approach that has been attempted to reduce reflected radiation problems has been to use a radiation absorbing layer interposed between the substrate surface and the photoresist coating layer. Reference Examples: PCT Application WO90 / 03598, EPO Application 0 639 941 A1 and US Pat. Nos. 4,910,122, 4,370,405, 4,362,809 and 5,939,236. Such layers are also referred to as antireflective layers or antireflective compositions. Reference: US Pat. No. 5,939,236, which is all assigned to Shipley Company and discloses very useful antireflective compositions; 5,886,102; 5,886,102; No. 5,851,738; And 5,851,730.

We have discovered new antireflective compositions for use with overcoated photoresist layers that can exhibit enhanced properties including enhanced storage stability (ie, shelf life stability).

The inventors have found that certain antireflective compositions may exhibit a limited shelf life, for example, during which the particulates are produced or suspended before use. In particular, certain antireflective coating compositions include an acid or thermal acid generating agent that limits the shelf life of the composition. While not wishing to be bound by theory, it is believed that the shelf life may be less desirable due to the interaction between the antireflective composition components.

We have found that the use of ionic thermal acid generator compounds can significantly enhance the storage stability of organic solvent antireflective compositions. Exemplary ionic thermal acid generators include, for example, arylsulfonate salts such as sulfonate salts, preferably toluenesulfonate acid amine salts.

The antireflective composition of the present invention suitably contains a resin and a thermal acid generator (TAG). Preferred antireflective compositions of the invention contain a crosslinking component, which is crosslinked prior to applying the photoresist composition layer to the antireflective composition layer. The antireflective composition may contain an oligomer or polymer thermal acid generator as the sole resin component of the antireflective composition. However, it is generally preferred that the antireflective composition contain at least one resin component in addition to any thermal acid generator component, for example to impart good film-forming properties to the antireflective composition.

The antireflective composition of the present invention will also contain components comprising chromophore groups capable of absorbing undesirable radiation used to expose the overcoated resist layer from retroreflection to the resist layer. Generally preferred chromophores are aromatic groups comprising both monocyclic and polycyclic aromatic groups such as optionally substituted phenyl, optionally substituted naphthyl, optionally substituted anthracenyl, optionally substituted phenanthracenyl, optionally substituted quinolinyl, and the like. to be. Particularly preferred chromophores may vary depending on the radiation used to expose the overcoated resist layer. More specifically, when exposing the overcoated resist at 248 nm, an optionally substituted anthracene is a chromophore of a particularly preferred antireflective composition. When the overcoated resist is exposed at 193 nm, optionally substituted phenyl is a particularly preferred chromophore of the antireflective composition. Preferably, such chromophore groups are bonded to the resin component of the antireflective composition, which is a polymer thermal acid generator component or additional resin component that is different in nature from the polymer base additive (e.g., pendant groups).

Preferred antireflective coating compositions of the invention mentioned can be crosslinked, for example, by heat and / or radiation treatment. For example, preferred antireflective coating compositions of the present invention may contain a separate crosslinker component that can be crosslinked with one or more other components of the antireflective composition. Generally preferred crosslinking antireflective compositions comprise a separate crosslinker component. Particularly preferred antireflective compositions of the present invention contain resins, crosslinkers and thermal acid generator additives as separate components. In addition, the crosslinking antireflective compositions of the present invention may also contain amine additives to facilitate the removal of footing or notching of the overcoated photoresist layer. The crosslinking antireflective composition is preferably crosslinked prior to applying the photoresist layer onto the antireflective coating layer. Thermal-induced crosslinking of the antireflective composition by activation of the thermal acid generator is generally preferred.

The antireflective composition of the present invention is typically formed as an organic solvent solution and applied to a substrate. Various solvents can be used to form the antireflective compositions of the present invention, including protic solvents such as ethyl lactate.

The antireflective composition of the present invention can be used with various types of overcoated photoresist. Preferred photoresists for use with the antireflective compositions of the invention include acetal or ketal groups (all referred to herein as acetal groups); Ester groups such as t-butyl ester groups, which may be provided for example by polymerization of t-butyl acrylate, t-butyl methacrylate, methyladamantyl acrylate and methyladamantyl methacrylate; Positive-functional chemically amplified photoresists, including photoresists containing components, typically resins, and the like. Such resist resins also include phenolic resin units which are desirable for imaging at other groups, such as deep UV wavelengths (248 nm); Or optionally substituted norbornene polymerized for resists imaged with non-aromatic groups, for example in particular with sub-200 nm radiation (eg 193 nm).

The present invention also provides a novel product comprising a method of forming a photoresist relief image and a substrate (eg, microelectronic wafer substrate) coated alone or in combination with the antireflective composition of the invention. do. In addition, the present invention provides a method of substantially reducing antireflective compositions that are stable to alcohols such as protic media, for example ethyl lactate, to extend shelf life prior to use of the antireflective composition in forming an antireflective coating on a substrate. Provide a neutral solution. Other aspects of the present invention are described below.

As mentioned above, substantially neutral or ionic thermal acid generator additives are stable for prolonged periods in the protic medium. Preferably the substantially neutral thermal acid generator composition is at least 1 or 2 months, more typically about 3, 4, 5, 6, 7, 8 or 9 in a protic medium such as water or alcohol that does not produce an acidic solution. Stable for more than a month

While not wishing to be bound by theory, the use of an ionic thermal acid generator in an antireflective composition of the present invention results in radiation-absorbing chromophores used in antireflective compositions (e.g., for antireflective compositions imaged at 248 nm). It is believed that undesirable bleaching of anthracene, anti-reflective composition imaged at 193 nm, and the like) can be suppressed.

It is also contemplated that the cationic component of the ionic thermal acid generator, in particular amine based anions, may provide a beneficial effect. More specifically, in the case of so-called low temperature photoresists with acetal resins, the pyrolytic ionic thermal acid generator can help fix the thermally generated acid to the antireflective composition coating layer. If the thermally generated acid is fixed to the antireflective composition coating layer, the acid will not migrate into the overcoated photoresist layer. As such, if the thermally generated acid moves undesirably into the resist layer, the resolution of the patterned image in the resist layer can be significantly impaired, for example, the developed resist relief image may result in a negative slope profile ( Undercutting), and the shifted heat-acid may lead to undesirable removal of the lower region of the unexposed resist layer.

In the case of so-called high temperature photoresists, for example resists containing ester photoacid-labile groups such as polymerized t-butylacrylate or t-butylmethacrylate units, volatile amines are used as cationic components for thermal acid generators. Use can provide significant benefits. In such a system, the amine can be removed (volatilized) from the antireflective composition coating layer during thermosetting of that layer.

Preferred substantially neutral thermal acid generator additives are sulfonate salts, such as carbocyclic aryl (eg, phenyl, naphthyl, anthracenyl, etc.), heteroaryl (eg thienyl) or aliphatic sulfonate salts, Preferably a carbocyclic aryl sulfonate salt. Thermal acid generator additives may be aromatic or non-aromatic. Preferred thermal acid generator additives contain optionally substituted benzenesulfonate salts, preferably para-alkylbenzenesulfonate salts.

Preferred thermal acid generator cations shown above contain at least one nitrogen. Preferred cations contain one or more optionally substituted amine groups. The amine-containing cation may contain one or more primary, secondary, tertiary and / or quaternary ammonium groups. Preferred amine-containing cations have one or more amine groups with active protons, for example primary, secondary and / or tertiary ammonium groups. Substituents of amine-containing cations of thermal acid generators are suitably for example optionally substituted alkyls, such as optionally substituted C _1-12 alkyl; Optionally substituted aryl, such as optionally substituted phenyl, naphthyl, anthracenyl, and the like; Optionally substituted heteroalkyl, such as optionally substituted C _1-12 heteroalkyl, in particular C _1-12 alkoxy and the like.

Primary, secondary or tertiary aliphatic amines are particularly preferred cationic components of the thermal acid generator used in the ARCs of the invention. For example, the cationic counter ions of the substantially neutral thermal acid generator compound of the present invention may be represented by the formula [(R ₁ ) (R ₂ ) (R ₃ ) NH] ⁺ (where R ₁ , R ₂ , R ₃ Is independently hydrogen or an optionally substituted alkyl group, such as optionally substituted C _1-16 alkyl, provided that at least one of R ₁ , R ₂ and R ₃ is not hydrogen).

Substituents of substituted carbocyclic aryl groups of the ionic carbocyclic aryl sulfonate salts of the invention include, for example, hydroxy; Optionally substituted alkyl, for example alkyl having 1 to about 16 carbon atoms, more typically alkyl having 1 to about 8 carbon atoms; Optionally substituted alkenyl, for example alkenyl having 2 to about 16 atoms, more typically alkenyl having 2 to about 8 atoms; Optionally substituted alkynyl, for example alkynyl having 2 to about 16 atoms, more typically alkynyl having 2 to about 8 carbon atoms; Optionally substituted alkoxy, for example alkoxy having 1 to about 16 atoms, more typically alkoxy having 1 to about 8 atoms; Optionally substituted carbocyclic aryl such as optionally substituted phenyl, optionally substituted naphthyl, optionally substituted anthracene and the like; Optionally substituted aralkyl, such as aralkyl having from 7 to about 20 carbon atoms, for example optionally substituted benzyl and the like; And preferably an optionally substituted heteroaromatic or heteroalicyclic group having 1 to 3 rings having 3 to 8 ring members in each ring and forming 1 to 3 heteroatoms, for example coumarinyl, quinoli Nilyl, pyridyl, parazinyl, pyrimidyl, furyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, benzothiazole, tetrahydrofuranyl, tetrahydropyranyl, Piperidinyl, morpholino and pyrrolidinyl; Etc. are included. It may also be 1, 2, 3, 4 or 5 independently selected substituents on the arene ring or, more specifically, may be optionally substituted by the substituents listed above in each case of the arene hydrogen substituent. Preferred arene groups have 0, 1 or 2 independently selected non-hydrogen substituents.

As described above, low molecular weight, substantially neutral, thermal acid generator additives, including non-polymeric, substantially neutral, thermal acid generator additives may also be suitably used in the antireflective compositions of the present invention. For example, suitable substantially neutral thermal acid generator additives include those having a molecular weight of less than about 600 Daltons, more typically less than about 500, 400, 300, 200 or 150 Daltons. The TAG additive will typically have a molecular weight of at least about 100, 125, 150 or 200 daltons.

Preferred low molecular weight ionic thermal acid generator additives which may be non-polymeric include, for example, the groups described above, ie hydroxy; Optionally substituted alkyl; Optionally substituted alkenyl; Optionally substituted alkynyl; Optionally substituted alkoxy; Optionally substituted carbocyclic aryl; Optionally substituted aralkyl; And optionally substituted heteroaromatic or heteroalicyclic group; Substituted sulfonate ammonium salts, including ammonium or primary, secondary and tertiary ammonium salts, which may be substituted by or the like.

The ionic thermal acid generator compound of the present invention may suitably have a relatively high molecular weight. Such high molecular weight materials tend to be less volatilized during thermal curing of the antireflective coating layer containing a substantially neutral thermal acid generator compound. Preferred high molecular weight substantially neutral thermal acid generator compounds have a molecular weight of at least about 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000 Daltons. Have a molecular weight of at least about 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3500, 4000, 4500, 5000, 6000, 7000, 8000, 9000, 10000, 15000, 20000, 30000 Daltons Higher molecular weight additives, such as substantially neutral thermal acid generator additives, will also be preferred. For polymeric materials, the molecular weight criterion herein is Mw.

Oligomeric and polymeric ionic thermal acid generator additives having arylsulfonic acid salts have arylsulfonic acid salt substituents in the polymer backbone or in the pendant moiety. Suitable oligomeric or polymeric sulfonate salts of the antireflective compositions of the invention may be formed by the polymerization of two or more separate monomers. Such monomers may be characterized as sulfonated monomers if they provide the neutral thermal acid generator properties of the polymer or as non-sulfonated monomers if they do not provide the neutral thermal acid generator properties of the polymer. Based on nomenclature, the preferred copolymer's substantially neutral thermal acid generator additive comprises from about 1 to about 50 mole percent sulfonated monomer, more preferably from about 2 to about 20 mole percent sulfonated monomer, Particularly preferably about 5 to about 10 mole percent sulfonated monomer.

In addition, suitable oligomeric or polymeric sulfonate salts of the antireflective compositions of the present invention may be prepared by post-polymerization methods that introduce sulfonic acid or sulfonate salts into the polymer. Sulfonation reactions are well known in the art and any suitable reaction that introduces sulfonate or sulfonic acid residues into the polymer can be tolerated. Non-limiting examples include sulfonation where the polymer or oligomer is treated with sulfuric acid, sulfur trioxide and similar sulfonation reagents. Based on the nomenclature above, suitable post-polymerized sulfonated substantially neutral thermal acid generator additives comprise from about 1 to about 50 mole percent sulfonated monomer, more preferably from about 2 to about 20 mole percent sulfonate. Fonned monomers, particularly preferably about 5 to about 10 mole percent sulfonated monomers.

The crosslinking antireflective composition of the present invention comprises a substantially neutral thermal acid generator, such as ammonium arerensulfonate, for inducing or promoting crosslinking during curing of the antireflective composition coating layer. Typically the nonpolymeric or nonoligomeric ionic thermal acid generator is present in the antireflective composition at a concentration of about 0.1 to 10 percent by weight of the total dry ingredients of the composition, more preferably about 2 percent by weight of the total dry ingredients. The substantially neutral thermal acid generator of the polymer or oligomer is present in the antireflective composition at a concentration of about 0.2 to about 20 weight percent of the total dry component of the composition, more preferably about 1 to about 5 weight percent of the total dry component. do. The concentration of the substantially neutral thermal acid generator of the polymer or oligomer depends on the mole percentage of the sulfonated monomers in the polymer additive, for example in the case of highly sulfonated polymer additives the substantially neutral thermal acid at low weight concentrations. Generators are suitable.

The antireflective composition described above may suitably contain a resin component in addition to the base additive material. Suitable resin components may contain chromophore units for absorbing the radiation used to image the overcoated resist layer before undesirable reflection occurs.

For deep UV applications (ie, overcoated resist is imaged by deep UV radiation), the polymer of the antireflective composition will preferably absorb reflection in the deep UV range (typically about 100 to 300 nm). Thus, the polymer preferably contains units that are deep UV chromophores, ie units that absorb deep UV radiation. High conjugate portions are generally stable chromophores. Aromatic groups, in particular polycyclic hydrocarbon or heterocyclic units, for example 2 to 3 or 4 fused or separate rings with 3 to 8 members in each ring or 0 to 3 N, O or S per ring Groups with atoms are typically preferred deep UV chromophores. Such chromophores are ring-substituted quinolini such as optionally substituted phenanthryl, optionally substituted anthracenyl, optionally substituted acridine, optionally substituted naphthyl, optionally substituted quinolinyl, and hydroxyquinolinyl groups. Neal. Particularly preferred is when optionally substituted anthracenyl groups image the overcoated resist at 248 nm. Preferred antireflective composition resins have pendant anthracene groups. Preferred resins include the resins of formula (I) as described on page 4 of Shipley Company's European Publication No. 813114A2.

Still other preferred resin binders include quinolinyl derivatives having one or more N, O or S ring atoms, such as optionally substituted quinolinyl groups, or hydroxyquinolinyl. The polymer may contain other units such as carboxy and / or alkyl ester units pendant from the polymer backbone. Particularly preferred antireflective composition resins are acrylic polymers containing such units, such as the resins of formula (II) described on pages 4-5 of European Publication Application No. 813114A2 to Shipley Company.

When imaging at 193 nm, the antireflective composition will preferably contain a resin with phenyl chromophore units. For example, one of the antireflective resins suitable for use with photoresist imaged at 193 nm is polymerized units of styrene, 2-hydroxyethylmethacrylate and methylmethacrylate (30:38:32 molar ratio). It is composed terpolymer. Its use in such phenyl group containing resins and antireflective compositions is disclosed in US application 09 / 153,575, filed in 1998 and in the corresponding European published application EP87600A1, assigned to Shipley Company.

Preferably the resin of the antireflective composition of the present invention has a weight average molecular weight (Mw) of about 1,000 to about 10,000,000 daltons, more typically about 5,000 to about 1,000,000 daltons, and a number average molecular weight (Mn) of about 500 to about 1,000,000 daltons. Will have The molecular weight (Mw or Mn) of the polymer of the present invention is suitably determined by gel permeation chromatography.

While antireflective composition resin binders having such absorbing chromophores are generally preferred, the antireflective compositions of the present invention may contain other resins as co-resins or as the sole resin binder component. For example, phenolic resins such as poly (vinylphenol) and novolak may be used. Such resins are disclosed in European application EP 542008 to Shipley Campani. Other resins described below as photoresist resin binders may also be used as the resin binder component of the antireflective composition of the present invention.

The concentration of such resin components of the antireflective composition of the present invention may vary relatively broadly, and generally the resin binder is about 50 to 95 weight percent of the total dry components of the antireflective composition, more typically the total dry component (solvent carrier All components except for) are used at a concentration of about 60 to 90% by weight.

The crosslinking antireflective composition of the present invention also contains a crosslinker component. Various crosslinkers can be used, including the antireflective composition crosslinkers disclosed in European Application 542008 to Shipley Co., which is incorporated herein by reference. Suitable antireflective composition crosslinkers, for example, include melamine resins, including melamine resins manufactured by American Cyanamid and sold under the trade names Cymel 300, 301, 303, 350, 370, 380, 1116 and 1130. Same amine-based crosslinkers. Particular preference is given to glycolurils, including glycoluril, available from American Cyanamide. Benzoguanamine and urea-based materials also include resins such as benzoguanamine resins available from American Cyanamide under the names Cymel 1123 and 1125, and urea resins available from American Cyanamide under the names Beetle 60, 65 and 80. Will be appropriate. In addition to those commercially available, such amine-based resins can be prepared by reacting acrylamide or methacrylamide copolymers with formaldehyde in, for example, alcohol-containing solutions, or separately from other suitable monomers with N-alkoxymethyl acrylamide or It can be prepared by copolymerization reaction of methacrylamide.

Suitable substantially neutral crosslinkers include hydroxy compounds, especially multifunctional compounds such as phenyl or other aromatic compounds with one or more hydroxy or hydroxy alkyl substituents, such as C _1-8 hydroxyalkyl substituents. Generally di-methanolphenol (C ₆ H ₃ (CH ₂ OH) ₂ OH) and other compounds with adjacent (within 1-2 ring atoms) hydroxy and hydroxyalkyl substituents, in particular one or more methanol or other hydroxyalkyl Preference is given to phenolic compounds such as ring substituents and phenyl or other aromatic compounds having at least one hydroxy adjacent to these hydroxyalkyl substituents.

Excellent lithography including substantial reduction of overcut or undercutting of photoresist relief images overcoated with a substantially neutral crosslinker such as methoxy methylated glycoluril used in the antireflective composition of the present invention (SEM test) It can provide performance characteristics.

Generally, the crosslinker component of the antireflective composition of the present invention comprises about 5 to 50 weight percent of the total solids (all components except the solvent carrier), more typically about 7 to 25 weight percent of the total solids of the antireflective composition. Exists as.

The antireflective composition of the present invention may also contain additional dye compounds that absorb the radiation used to expose the overcoated photoresist layer. Other optional additives include surface leveling agents, for example planarizing agents available under the trade name Silwet 7604 from Union Carbide, or surfactants FC 171 or FC 431 available from 3M Company. do.

To prepare the liquid coating composition, the components of the antireflective composition may include, for example, ethyl lactate or one or more glycol ethers such as 2-methoxyethyl ether (diglyme), ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; Solvents with both ether and hydroxy moieties such as methoxy butanol, ethoxy butanol, methoxy propanol and ethoxy propanol; Suitable solvents such as esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate and other solvents such as dibasic esters, propylene carbonate and gamma-butyrolactone Dissolved in. The concentration of the dry ingredients in the solvent will depend on several factors such as the method of application. Generally, the solids content of the antireflective composition varies from about 0.5 to 20 weight percent of the total weight of the antireflective composition, preferably the solids content varies from about 2 to 10 weight percent of the antireflective composition.

Various photoresist compositions can be used with the antireflective compositions of the present invention, including positive-functional and negative-functional photoacid-generating compositions. Photoresists used with the antireflective compositions of the present invention typically comprise a resin binder and a photoactive component, typically a photoacid generator compound. Preferably the photoresist resin binder has a functional group that imparts alkaline aqueous developability to the imaged resist composition.

As mentioned above, particularly preferred photoresists for use with the antireflective compositions of the present invention are those in which the photoactivated acid in the resist layer induces a deprotection reaction of one or more composition components, thereby exposing the exposed and non-exposed areas of the resist coating layer. Chemically amplified resists, in particular positive-functional chemically amplified resists, which provide a difference in hepatic solubility. Many chemically-amplified resist compositions are described, for example, in US Pat. No. 4,968,581; No. 4,883,740; No. 4,810,613; 4,491,628 and 5,492,793, all of which are incorporated herein by reference for the teachings of making and using chemically amplified positive-functional resists.

As mentioned above, antireflective compositions are also suitably used with positive chemically-amplified photoresists having acetals which are deblocked in the presence of photoacids. Such acetal based resists are disclosed, for example, in US Pat. Nos. 5,929,176 and 6,090,526.

The antireflective compositions of the present invention may also be used with other positive resists, including resists containing resin binders containing polar functional groups such as hydroxyl or carboxylates, which are used to develop the resist with an aqueous alkaline solution. It is used in the resist composition in a sufficient amount. Generally preferred resist resin binders are phenolic resins including phenol aldehyde condensates known in the art as novolak resins, homo and copolymers of alkenyl phenols and homo and copolymers of N-hydroxyphenyl-maleimide.

Copolymers containing phenols and nonaromatic cyclic alcohol units are also preferred resin binders for the resists of the present invention and may be suitably prepared by partial hydrogenation of novolak or poly (vinylphenol) resins. Its use in such copolymer and photoresist compositions is disclosed in US Pat. No. 5,128,232 to Thackeray et al.

Preferred negative-functional resist compositions for use with the antireflective compositions of the invention comprise a mixture of materials that will cure, crosslink or harden upon exposure to acid, and a photoacid generator.

Particularly preferred negative-functional resist compositions include resin binders such as phenolic resins, crosslinker components of the present invention and photoactive components. Such compositions and their use are disclosed in European Patent Applications 0164248 and 0232972 to Tacoray et al. And US Pat. No. 5,128,232. Preferred phenolic resins for use as the resin binder component include poly (vinylphenol) and novolak as described above. Preferred crosslinkers include amine based materials including melamine, glycoluril, benzoguanamine based materials and urea based materials. In general, melamine-formaldehyde resins are most preferred. Such crosslinkers are commercially available and are, for example, melamine resins sold by American Cyanamide under the trade names Cymel 300, 301 and 303. Glycoluril resins are marketed by American Cyanamide under the trade names Cymel 1170, 1171, 1172, Powderlink 1174, and urea-based resins are marketed under the trade names Beetle 60, 65 and 80, and benzoguanamine resins are under the trade names Cymel 1123 and It is marketed under 1125.

Suitable photoacid generator compounds of resists for use with the antireflective compositions of the present invention include onium salts, such as those disclosed in US Pat. Nos. 4,442,197, 4,603,101 and 4,624,912, each incorporated herein by reference; And nonionic organic photoactive compounds such as sulfonated photoacid generators, including halogenated photoactive compounds such as U.S. Pat. No. 5,128,232 to Tacoray et al., And sulfonated esters and sulfonyloxy ketones. See the disclosure of suitable sulfonate PAGs, including benzoin tosylate, t-butylphenyl alpha- (p-toluenesulfonyloxy) -acetate and t-butyl alpha- (p-toluenesulfonyloxy) -acetate. J. of Photopolymer Science and Technology, 4 (3): 337-340 (1991). Preferred sulfonate PAGs are also disclosed in US Pat. No. 5,344,742 to Sinta et al. The camphorsulfonate PAGs 1 and 2 are also preferred photoacid generators for resist compositions used with the antireflective compositions of the invention, in particular the chemically-amplified resists of the invention.

Photoresists for use with the antireflective compositions of the present invention may also contain other materials. For example, other optional additives include actinic and contrast dyes, anti-striation agents, plasticizers, and speed enhancers. Such optional additives will typically be present in small concentrations in the photoresist composition, although fillers and dyes may be present in relatively large concentrations such as from about 5 to 50 weight percent of the total weight of the resist dry component.

Antireflective compositions of the present invention comprising a low base group crosslinker such as a suitable glycoluril are strong acids upon exposure, such as triflic acid, camphor sulfonic acid or other sulfonic acids, or other acids having a pKa (25 ° C.) of about 2 or less. It is particularly useful for photoresists that produce photo products.

Without wishing to be bound by theory, the antireflective compositions of the present invention are particularly effective for such strong acid resists, where strong photoacids are released from the resist as compared to corresponding antireflective compositions containing more basic crosslinkers. This is because the amount remaining in the antireflective composition is small. That is, the low base group crosslinker of the present invention will bind the strong photogenerated acid of the overcoated resist layer to a lower extent than the crosslinker of the highly basic antireflective composition. As a result, a small amount of acid is lost from the resist layer, and resolution problems such as footing will be further reduced.

Various substituents and materials (including substantially neutral thermal acid generators, resins, etc.) as "optionally substituted" may be, for example, halogen (F, Cl, Br, I) at one or more required positions; Nitro; Hydroxy; Amino; Alkyl such as C _1-8 alkyl; Alkenyl, such as C _2-8 alkenyl; Alkylamino such as C _1-8 alkylamino; Carbocyclic aryl such as phenyl, naphthyl, anthracenyl and the like; And the like may be appropriately substituted.

In use, the antireflective composition of the present invention is applied as a coating layer to a substrate by various methods such as spin coating. Generally, the antireflective composition is applied onto the substrate in a dry layer of about 0.02 to 0.5 μm thick, preferably a dry layer of about 0.04 to 0.20 μm thick. The substrate is suitably a substrate used in a method relating to photoresist. For example, the substrate may be a microelectronic wafer made of silicon, silicon dioxide or aluminum-aluminum oxide. Gallium azenide, silicon carbide, ceramic, quartz or copper substrates may also be used. Substrates used for liquid crystal displays or flat panel displays, for example glass substrates, substrates coated with indium tin oxide, and the like, are also suitably used. Substrates for optical and optical-electronic devices (eg waveguides) may also be used.

The antireflective coating layer is preferably cured before applying the photoresist composition onto the antireflective composition. Curing conditions will vary depending on the components of the antireflective composition. In particular, the curing temperature will depend on the particular substantially neutral thermal acid generator. Typical curing conditions are about 0.5 to 40 minutes at about 80 to 225 ° C. The curing conditions are preferably determined such that the antireflective composition coating layer is substantially insoluble in the photoresist solvent and the alkaline aqueous developer.

After this curing the photoresist is applied onto the surface of the antireflective composition. In the application of the antireflective composition, the photoresist may be applied via any standard method such as rotation, dipping, meniscus or roller coating. After application, it is typical to remove the solvent by drying the photoresist coating layer, preferably until the resist layer is not tacky. Optimally, the intermixing of the antireflective composition layer and the photoresist layer should be substantially non-existent.

The resist layer is then imaged with activating radiation through a mask in a conventional manner. The exposure energy is then sufficient to effectively activate the photoactive component of the resist system to form a patterned image in the resist coating layer. The exposure energy typically ranges from about 3 to 300 mJ / cm 2, depending in part on the exposure mechanism and the particular resist and resist processing method used. The exposed resist layer is post-exposure baked as needed to create or increase the solubility difference between the exposed and non-exposed areas of the coating layer. For example, negative acid-cured photoresists typically require post-exposure heat treatment to induce an acid-promoted crosslinking reaction, and many chemically amplified positive-functional resists are acid-promoted. Post-exposure heat treatment is required to induce the deprotection reaction. Typically post-exposure bake conditions include a temperature of at least about 50 ° C., more specifically from about 50 to about 160 ° C.

The exposed resist coating layer is then preferably developed using an aqueous substrate developer such as tetrabutyl ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium silicate, sodium metasilicate, aqueous ammonia, and the like. . In addition, an organic developer may be used. In general, the development treatment is carried out according to methods known in the art. After development, the final baking of the acid-cured photoresist is carried out at a temperature of about 100 to about 150 ° C. for several minutes to further cure the developed and exposed coated layer areas.

This developed substrate can selectively process the substrate region stripped of the photoresist, for example, by chemically etching or plating the substrate region stripped of the photoresist according to methods known in the art. Suitable etchantes include hydrofluoric acid etchant and oxygen plasma gas etch (eg, oxygen plasma etch). The plasma gas etch removes the crosslinked antireflective coating layer.

All documents mentioned herein are incorporated herein by reference. The following examples are provided to illustrate the present invention, and the present invention is not limited thereto.

Example 1 Synthesis of ARC Polymer

A starting volume of 249 kg THF was charged to a 100 gallon reactor using residual vacuum. 21.05 kg 9-anthracene methyl methacrylate (Antma) was added to the reactor and mixed with THF until dissolved. 16.00 kg of pre-weighed methyl methacrylate (MMA), 12.5 kg 2-hydroxyethyl methacrylate (HEMA) and Vazo 65 free radical initiator solution were added to the reactor. The reaction mixture was stirred under vacuum and washed three times with nitrogen to remove dissolved oxygen. After the final nitrogen wash, the vessel was heated to a reaction temperature of 66 ° C. and treated for 30 hours at reflux and atmospheric pressure.

MTBE was used as the precipitation solvent and filled into the precipitation vessel via vacuum. Once the reaction was complete and the batch cooled down, the batch was introduced through the spray nozzle into the precipitation vessel in several increments for precipitation to form a slurry. The product was filtered using a 48 "Hastelloy buchner funnel equipped with a 100 μm polyprop filter bag. The cake was washed with additional MTBE. The dam was placed in a filter gage on a Buchner funnel and air was passed over the filter cake to remove the MTBE. Removed and dried the cake PGME was charged to the treatment vessel, then the filter cake was charged to the treatment vessel for vacuum stripping of MTBE The final product was made as a 14-16% polymer solution in PGME.

All treatment units were washed with propylene glycol methyl ether (PGME) followed by acetone. Plastic containers can be cleaned with THF after use. About 200 grams of phenothiazine inhibitor was added to the treated filtrate of THF and MTBE to inhibit peroxide formation.

Example 2 Reference ARC Containing Nonionic TAG (Comparative Example)

0.7845 g of the polymer of Example 1, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of p-nitrobenzyltosylate thermal acid generator, 0.0072 g of FC 430 surfactant (3M Corporation), and Antireflective compositions were prepared by dissolving 30.96 g of propylene glycol methyl ether alcohol solvent together. After dissolution, the solution was filtered through a propylene filter having a pore size of 0.2 μm.

The filtered solution was then spin-cast onto a 100 mm silicon wafer and baked at 175 ° C. to obtain a film thickness of about 600 angstroms. SE430 (Shin Etsu Corp.), usually a commercially available "hybrid-acetal resist", is spin coated on top of the antireflective film and then baked at 90 ° C. for 60 seconds to 6000 The film thickness of Angstrom was obtained. This resist was then exposed on a GCA 0.55NA stepper through a mask using 248 nm light to form the same line / space pattern of various resolutions on the film. This resist film was then baked for 60 seconds at 100 ° C. after exposure and developed with a 2.38% tetramethyl ammonium hydroxide developer using a standard wafer-track single-puddle process.

The developed wafer was inspected using a scanning electron microscope to determine patterned fidelity. The exposure dose was chosen to give a line / space pattern of the same size.

SE430 resist on the antireflective film of the composition provided insufficient pattern fidelity. This resist sidewall was significantly undercut at the resist / antireflective interface. At resolutions less than or equal to 240 nm, the resist undercut was too severe to be sufficient to completely collapse the pattern.

This example illustrates the problems experienced by antireflective compositions containing non-ionic thermal acid generators.

Example 3: Reference ARC Containing Acidic Crosslinking Catalyst

0.7845 g of the polymer of Example 1, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of p-toluene sulfonic acid monohydrate (acid crosslinking catalyst consisting of Aldrich Corp., FC 430) An antireflective composition was prepared by dissolving 0.0072 g of surfactant (3M Corporation) and 30.96 g of propylene glycol methyl ether alcohol solvent, after dissolution, the solution was filtered through a propylene filter with a pore size of 0.2 μm.

The filtered solution was then spin-cast on a 100 mm silicon wafer and baked at 175 ° C. to obtain a film thickness of about 600 angstroms. SE430 (Sin-Etsu Corporation), usually a commercially available "hybrid-acetal resin", was spincoated on top of the antireflective film and then baked at 90 ° C. for 60 seconds to obtain a film thickness of 6000 Angstroms. This resist was then exposed on a GCA 0.55NA stepper through a mask using 248 nm light to form the same line / space pattern of various resolutions on the film. This resist film was then baked at 110 ° C. for 60 seconds after exposure and developed with a 2.38% tetramethyl ammonium hydroxide developer using standard wafer-track single-puddle method.

The developed wafers were inspected using a scanning electron microscope to determine patterned fidelity. The exposure dose was chosen to give a line / space pattern of the same size.

SE430 resist exhibited a "bowed" resist outer wall appearance with an undercut at the resist / antireflective interface. Undercut was less than that measured in Example 2.

Example 4 ARC Using Ionic Thermal Acid Generator

The thermal acid generator (TAG) evaluated in this example was Nacure 5225, an amine salt of dodecylbenzene sulfonic acid.

Acid crosslinking catalyst consisting of 0.7845 g of the polymer of Example 1, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of Nacure 5225 (King Industries), FC 430 surfactant (3M Corporation) 0.0072 g and 30.96 g of propylene glycol methyl ether alcohol solvent were dissolved together to prepare an antireflective composition. After dissolution, the solution was filtered through a propylene filter having a pore size of 0.2 μm.

The filtered solution was then spin-cast onto a 100 mm silicon wafer and then baked at 175 ° C. to obtain a film thickness of about 600 Angstroms. SE430 (Sin-Etsu Corporation), usually a commercially available "hybrid-acetal resin", was spincoated on top of the antireflective film and then baked at 90 ° C. for 60 seconds to obtain a film thickness of 6000 Angstroms. This resist was then exposed on a GCA 0.55NA stepper through a mask using 248 nm light to form the same line / space pattern of various resolutions on the film. This resist film was then baked for 60 seconds at 110 ° C. after exposure and developed with a 2.38% tetramethyl sodium hydroxide developer using a standard wafer-track single-puddle method.

The developed wafers were inspected using a scanning electron microscope to determine patterned fidelity. The exposure dose was chosen to give a line / space pattern of the same size.

SE430 resist exhibited a "straight" resist outer wall appearance without undercuts and footings at the resist / antireflective interface. It has the characteristic of 200 nm resolution which shows the tendency not to tilt and was excellent in the adhesiveness of the resist.

Example 5 ARC Using Ionic Thermal Acid Generator

The thermal acid generator evaluated in this example was Nacure XC 9225, an amine salt of dinonylnaphthalene sulfonic acid.

0.7845 g of the polymer of Example 1, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of Nacure 5225 (King Industries), 0.0072 g of FC 430 surfactant (3M Corporation) And 30.96 g of propylene glycol methyl ether alcohol solvent were dissolved together to prepare an antireflective composition. After dissolution, the solution was filtered through a propylene filter having a pore size of 0.2 μm.

The filtered solution was then spin-cast on a 100 mm silicon wafer and baked at 175 ° C. to obtain a film thickness of about 600 angstroms. SE430 (Sin-Etsu Corporation), usually a commercially available "hybrid-acetal resin", was spincoated on top of the antireflective film and then baked at 90 ° C. for 60 seconds to obtain a film thickness of 6000 Angstroms. This resist was then exposed on a GCA 0.55NA stepper through a mask using 248 nm light to form the same line / space pattern of various resolutions on the film. This resist film was then baked at 110 ° C. for 60 seconds after exposure and developed with a 2.38% tetramethyl ammonium hydroxide developer using standard wafer-track single-puddle method.

The developed wafers were inspected using a scanning electron microscope to determine patterned fidelity. The exposure dose was chosen to give a line / space pattern of the same size.

SE430 resist exhibited a straight resist outer wall appearance without undercuts and footings at the resist / antireflective interface. It has the characteristic of 200 nm resolution which shows the tendency not to tilt and was excellent in the adhesiveness of the resist.

Example 6 Improvement of Anti-Reflection Agent Shelf Life Using Ionic Thermal Acid Generators

It has been found that organic antireflector compositions undergo chemical changes over time, and the rate of change increases with higher storage temperature. Since changes in film absorbance, refractive index and density of crosslinking can adversely affect lithographic performance, it is desirable that the chemical properties of the antireflective film remain unchanged. One of the changes over time observed in prior antireflective agents is the change in absorption spectrum with storage time. While not intending to be established by theory, it is believed that the change is caused by the oxidation of chromophore groups by acidic species in the antireflective solution.

Time course phenomena were investigated by storing the antireflective agent solution at 40 ° C. to accelerate the time course of treatment. The previous antireflective composition containing p-toluene sulfonic acid as the crosslinking catalyst was compared to the antireflective composition containing Nacure 5225 as the crosslinking catalyst. Absorbance was measured at 220 nm, and this peak was found to correlate with the observed absorbance change at 250 nm and even 300-400 nm. Prior to measuring absorbance in the quartz cell, the antireflector sample was removed and diluted to the same fixed concentration with THF.

Antireflective with Nacure 5225 Ionic TAG

0.6682 g of the polymer of Example 1, 0.1177 g of a trimer condensate (plasticizer) of resorcinol and diethylol-p-cresol, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of Nacure 5225 ( An antireflective composition was prepared by dissolving together an acid crosslinking catalyst consisting of King Industries, 0.0072 g of FC 430 surfactant (3M Corporation) and 30.96 g of propylene glycol methyl ether alcohol solvent. After dissolution, the solution was filtered through a propylene filter having a pore size of 0.2 μm.

Anti-reflective agent containing p-toluenesulfonic acid catalyst

0.6682 g of the polymer of Example 1, 0.1177 g of a trimer condensate (plasticizer) of resorcinol and diethylol-p-cresol, 0.0990 g of Powderlink 1174 crosslinker (from Cytec Industries), 0.009 g of p-toluene An antireflective composition was prepared by dissolving together an acid crosslinking catalyst consisting of sulfonic acid monohydrate (Aldrich), 0.0072 g of FC 430 surfactant (3M Corporation) and 30.96 g of propylene glycol methyl ether alcohol solvent. After dissolution, the solution was filtered through a propylene filter having a pore size of 0.2 μm.

Initial absorbance at 220 nm at zero time after dilution into THF:

Reflector with Nacure 5225 Ionic TAG: 0.0718 Absorbance Unit

Reflector containing p-toluene sulfonic acid catalyst: 0.0254 absorbance unit

Absorbance at 220 nm of reflector 2 days at 40 ° C .:

Reflector with Nacure 5225 ionic TAG: 0.0722 absorbance unit

Reflector containing p-toluene sulfonic acid catalyst: 0.1655 absorbance unit

These results demonstrate that the antireflective composition of the present invention showed a change over time in the absorption spectrum at a rate of only 3% of the preceding antireflective agent containing an acidic catalyst.

It is to be understood that the foregoing description of the invention is illustrative only and that modifications and variations can be made without departing from the scope or spirit of the invention as set forth in the claims below.

Antireflective compositions containing the ionic thermal acid generator material of the present invention can significantly increase the shelf life of antireflective composition solutions and can be effectively used at a wide range of wavelengths used to expose overcoated photoresist layers.

Claims (32)

Antireflective compositions containing ionic thermal acid generators and resins; And a photoresist layer over the antireflective composition layer. The substrate of claim 1, wherein the antireflective composition layer further comprises a crosslinker component. The substrate of claim 1, wherein the antireflective composition is crosslinked. The substrate of claim 1, wherein the thermal acid generator is a sulfonate salt. The substrate of claim 4, wherein the sulfonate salt contains counter ions comprising one or more amine groups. The substrate according to claim 1, wherein the thermal acid generator contains a nitrogen-containing cationic component. The substrate according to any one of claims 1 to 5, wherein the thermal acid generator contains a cationic component which is an amine. The substrate according to any one of claims 1 to 5, wherein the thermal acid generator contains a cationic component which is a primary, secondary or tertiary aliphatic amine. The substrate of claim 1, wherein the thermal acid generator has a molecular weight of less than 500. 10. The substrate of claim 1, wherein the thermal acid generator is a polymeric material. The substrate of claim 1, wherein the antireflective composition contains a crosslinking agent that is crosslinked with an acid. The substrate according to any one of claims 1 to 11, wherein the antireflective composition contains a resin different from the thermal acid generator. 13. The substrate of any of claims 1 to 12, wherein the antireflective layer contains an aromatic group. The substrate of claim 1, wherein the antireflective layer contains anthracenyl, naphthalene or phenyl groups. The substrate according to any one of claims 1 to 14, wherein the antireflective composition layer contains a resin having a phenyl group. The substrate according to any one of claims 1 to 15, wherein the antireflective composition layer contains a resin having naphthyl groups. The substrate according to any one of claims 1 to 16, wherein the antireflective composition layer contains a resin having an anthracenyl group. The substrate of claim 1, wherein the photoresist composition is a chemically-amplified positive photoresist composition. 19. The substrate of any of claims 1 to 18, wherein the photoresist contains a resin containing a photoacid-labile acetal group. 19. The substrate of any of claims 1-18, wherein the photoresist contains a resin containing a photoacid-labile ester group. An antireflective composition containing an ionic thermal acid generator compound. The antireflective composition of claim 21 wherein the thermal acid generator is a sulfonate salt. 23. The antireflective composition of claim 21 or 22 wherein the thermal acid generator is an aryl sulfonate salt. The antireflective composition of claim 21, wherein the thermal acid generator is a sulfonate having at least one substituent selected from the group consisting of optionally substituted phenyl, optionally substituted naphthyl and optionally substituted anthracene. . 25. The antireflective composition of any of claims 21 to 24, wherein the sulfonate salt is an amine salt. 26. The antireflective composition of any of claims 21-25, wherein the thermal acid generator contains a nitrogen-containing cationic component. 27. The antireflective composition of any of claims 21 to 26, wherein the thermal acid generator is a tri (C ₁ -C ₁₂ alkyl) ammonium salt. Applying the antireflective composition of any of claims 21 to 27 onto a substrate; Applying a photoresist layer over the antireflective composition layer; Exposing and developing the photoresist layer to provide a resist relief image. The method of claim 28, wherein the antireflective layer is crosslinked prior to applying the photoresist layer. The method of claim 28, wherein the antireflective layer is thermoset prior to applying the photoresist layer. 31. The method of any one of claims 28-30, wherein the photoresist layer is exposed with radiation having a wavelength of less than about 250. 31. The method of any one of claims 28-30, wherein the photoresist layer is exposed with radiation having a wavelength of less than about 200.