Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
  • C08G8/04—Condensation polymers of aldehydes or ketones with phenols only of aldehydes
  • C08G8/08—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ
  • C08G8/10—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ with phenol
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/022—Quinonediazides
  • G03F7/023—Macromolecular quinonediazides; Macromolecular additives, e.g. binders
  • G03F7/0233—Macromolecular quinonediazides; Macromolecular additives, e.g. binders characterised by the polymeric binders or the macromolecular additives other than the macromolecular quinonediazides
  • G03F7/0236—Condensation products of carbonyl compounds and phenolic compounds, e.g. novolak resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G14/00—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00
  • C08G14/02—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00 of aldehydes
  • C08G14/04—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00 of aldehydes with phenols

Definitions

• the present invention relates to a phenol novolak resin which is useful as a film-forming component of a photosensitive composition, to a process for synthetically producing the resin, and to a positive photoresist composition using the resin.
• Phenol novolak resins obtained by condensation reaction of phenols such as cresol, xylenol, and trimethylphenol are generally used as film-forming components of positive photoresist compositions.
• a positive photoresist composition for use in i-line (365 nm) lithography a positive photoresist composition including the phenol novolak resin and a 1,2-naphthoquinonediazide-group-containing compound is excellent in sensitivity, definition, and heat resistance and is widely practically used in the fields of the manufacture of semiconductor integrated circuits (ICs).
• conventional positive photoresist compositions have strong tendency of reduction in film thickness and are believed not to form a fine pattern of not more than 0.35 ⁇ m with a good shape.
• the pattern is tapered to thereby invite twist of pattern formation in an isolation pattern, and a separated pattern cannot be significantly formed or the film thickness is significantly reduced in a dense pattern.
• a phenol novolak resin having a p-cresol constitutional unit or 3,4-xylenol constitutional unit is believed to be suitable for the preparation of a high definition positive photoresist composition.
• a positive photoresist composition using a phenol novolak resin containing p-cresol constitutional unit cannot provide satisfactory sensitivity compatible with high definition, and a positive photoresist composition using a phenol novolak resin containing 3,4-xylenol constitutional unit cannot form a satisfactory isolation pattern and the resulting isolation pattern is low in focal depth range properties, although the composition is excellent in sensitivity and definition.
• novolak resins containing xylenol constitutional unit or trimethylphenol constitutional unit have been proposed as such resist materials, but even these novolak resins cannot form dense patterns and isolation patterns with good shapes without deterioration in sensitivity and definition, in the formation of fine resist patterns of not more than 0.35 ⁇ m.
• Phenol novolak resins synthetically produced from two or more types of phenols are generally used in the positive photoresist composition. Individual phenols have, however, different reactivity. For example, p-cresol has a poor reactivity and most of p-cresol used as a starting material provides oligo-nuclear products.
• part or overall of low-molecular-weight fractions having a molecular weight of not more than 2000, such as oligo-nuclear products of p-cresol, of phenol novolak resins used in the positive photoresist composition are removed by fractionation operation. Accordingly, if the amount of such oligo-nuclear products is large, the yield of the resulting phenol novolak resin is decreased and the production cost of the positive photoresist composition is increased.
• phenol novolak resins is synthetically produced by using 3,5-xylenol, m-cresol, 3,4-xylenol, 2,5-xylenol, and other phenols having a high reactivity.
• This phenol novolak resin may have different resin composition [proportions of individual constitutional units or the ratio of ortho-ortho bond(o-o)/ortho-para bond (o-p)/para-para bond (p-p)] in high molecular weight fractions and in low molecular weight fractions of the resin, and the fractionation operation invites great variations in resin characteristics.
• the phenol novolak resin cannot therefore significantly provide a positive photoresist composition having stable characteristics.
• Another object of the present invention is to provide a phenol novolak resin that is suitable for the preparation of the positive photoresist composition.
• Yet another object of the present invention is to provide a phenol novolak resin which includes minimized oligo-nuclear products of phenols and has a uniform resin composition both in high molecular weight fractions and in low molecular weight fractions in the production of a phenol novolak resin using two or more types of phenols as materials, and a process for synthetically producing the phenol novolak resin.
• a phenol novolak resin having a specific structure and a positive photoresist composition prepared from the phenol novolak resin can achieve the above objects.
• the present invention provides, in an aspect, a phenol novolak resin (1) which has a peak intensity ratio of ortho-ortho bond (o-o)/ortho-para bond (o-p)/para-para bond (p-p) not substantially varying in each molecular weight fraction and which has a weight average molecular weight (Mw) in terms of polystyrene of 3000 to 20000, which peak intensity ratio is detected in a resin structure by 13 C-NMR analysis.
• Mw weight average molecular weight
• the phenol novolak resin (1) may preferably include at least two selected from among phenol constitutional units represented by the following formulae (I) to (IV):
• the present invention provides a phenol novolak resin (2) which has a peak intensity ratio of ortho-ortho bond (o-o)/ortho-para bond (o-p)/para-para bond (p-p) in a range of 3.0-5.0/2.0-3.5/1, which peak intensity ratio is detected in a resin structure by 13 C-NMR analysis and does not substantially vary in each molecular weight fraction, and which includes phenol constitutional units represented by the formulae (I) and (III) and the following formula (V); and which has a weight average molecular weight (Mw) in terms of polystyrene of 3000 to 20000.
• the ratio of the peak intensities of para-para bond (p-p) to the total of the peak intensities of ortho-ortho bond, ortho-para bond, and para-para bond [(o-o)+(o-p)+(p-p)] may preferably fall in a range of 10% to 20%.
• the present invention provides, in a further aspect, a phenol novolak resin (3) which has a peak intensity ratio of ortho-ortho bond (o-o)/ortho-para bond (o-p)/para-para bond (p-p) in a range of 5.0-8.5/2.5-4.5/1 and which includes phenol constitutional units represented by the formulae (I) and (II) and the following formula (VI), which peak intensity ratio is detected in a resin structure by 13 C-NMR analysis.
• This phenol novolak resin has a weight average molecular weight in terms of polystyrene of 3000 to 20000.
• the ratio of the peak intensities of para-para bond (p-p) to the total of the peak intensities of ortho-ortho bond, ortho-para bond, and para-para bond [(o-o)+(o-p)+(p-p)] may preferably fall in a range of 5% to 15%.
• a resin film formed by the use of the phenol novolak resins (1) to (3) preferably dissolves in a 2.38% by weight aqueous tetramethylammonium hydroxide solution at 25° C. at a rate of 0.01 to 0.001 ⁇ m/s.
• the present invention provides, in yet another aspect, a process for producing a phenol novolak resin which includes the steps of: (a) subjecting a phenol to a polycondensation reaction in the presence of an acid catalyst; (b) removing water from a reaction system; (c) decomposing, in the presence of an acid catalyst, the polycondensation product obtained in the step (a); and (d) subjecting the resulting product to a polycondensation reaction with an aldehyde or a ketone.
• the present invention provides a positive photoresist composition which includes the phenol novolak resins (1) to (3) and a 1,2-naphthoquinonediazide-group-containing compound.
• Preferred phenol novolak resins (1) and (2) having a specific structure for use in the present invention have the ratio of peak intensities of o-o/o-p/p-p in a resin structure detected by 13 C-NMR analysis not substantially varying in each molecular weight fraction and have a weight average molecular weight (Mw) of 3000 to 20000.
• Mw weight average molecular weight
• the term “not substantially vary” as used herein means that the ratio of peak intensities varies within a range of, for example, ⁇ 30%, and preferably in a range of ⁇ 20%.
• phenol novolak resin (1) those having at least two phenol constitutional units represented by the formulae (I) to (IV) in a resin structure are preferred. Phenol novolak resins having these constitutional units exhibit satisfactory characteristics such as sensitivity, definition, and focal depth range properties in the preparation of a positive photoresist composition.
• a phenol novolak resin having the constitutional units (I), (II), and (III) [Resin 1] and a phenol novolak resin having the constitutional units (I), (III), and (IV) [Resin 2] are specifically preferred as a resin component of a positive photoresist composition.
• Resin 1 preferably has a ratio of peak intensities of o-o/o-p/p-p in a range of 3.0-5.0/2.0-3.5/1, and further preferably has a ratio of peak intensity of p-p bond (p-p) to the total of peak intensities in a resin [(o-o)+(o-p)+(p-p)] in a range of 10% to 20%.
• Resin 2 preferably has a ratio of peak intensities of 0-010-p/p-p in a range of 4.0-5.0/1.5-2.5/1, and further preferably has a ratio of peak intensity of p-p bond (p-p) to the total of peak intensities in a resin [(o-o)+(o-p)+(p-p)] in a range of 10% to 20%.
• a preferred phenol novolak resin has a peak intensity ratio of ortho-ortho bond (0-o)/ortho-para bond (o-p)/para-para bond (p-p) in a range of 3.0-5.0/2.0-3.5/1, which peak intensity ratio is detected in a resin structure by 13 C-NMR analysis and does not substantially vary in each molecular weight fraction.
• This phenol novolak resin includes phenol constitutional units represented by the formulae (I), (III)a and (V), and has a weight average molecular weight (Mw) in terms of polystyrene of 3000 to 20000.
• Resin 3 preferably has a ratio of peak intensity of p-p bond (p-p) to the total of peak intensities in a resin [(0 o)+(o-p)+(p-p)] in a range of 10% to 20%.
• a preferred phenol novolak resin has a peak intensity ratio of ortho-ortho bond (o-o)/ortho-para bond (o-p)/para-para bond (p-p) in a range of 5.0-8.5/2.5-4.5/1, and preferably in a range of 6.0-7.5/3.0-4.0/1, the peak intensity ratio is detected in a resin structure by 13 C-NMR analysis.
• This phenol novolak resin includes phenol constitutional units represented by the formulae (I), (III), and (VI), and has a weight average molecular weight (Mw) in terms of polystyrene of 3000 to 20000.
• Resin 4 preferably has a ratio of peak intensity of p-p bond (p-p) to the total of peak intensities in a resin [(o-o) +(o-p)+(p-p)] in a range of 5% to 15%.
• o-o bond used herein means an alkylene bond through which two phenol constitutional units are bound at the o-positions of hydroxyl groups of both phenol constitutional units.
• o-p bond means an alkylene bond through which two phenol constitutional units are bound at the opposition of a hydroxyl group of one phenol constitutional unit and at the p-position of a hydroxyl group of the other phenol constitutional unit.
• p-p bond means an alkylene bond through which two phenol constitutional units are bound at the p-positions of hydroxyl groups of both phenol constitutional units.
• the phenol novolak resins of the present invention preferably have a weight average molecular weight (Mw) in terms of polystyrene of about 4000 to 10000.
• Mw weight average molecular weight
• Such phenol novolak resins can be advantageously used in the formation of a fine resist pattern of not more than 0.35 pm and can yield satisfactory sensitivity, definition, and focal depth range properties.
• the film When a resin film of the phenol novolak resin having a Mw in the aforementioned range is formed, the film preferably dissolves in a 2.38% by weight aqueous tetramethylammonium hydroxide solution at 25° C. at a rate of 0.01 to 0.001 ⁇ m/s.
• This type of phenol novolak resin can yield a positive photoresist composition having an improved sensitivity without deterioration in definition.
• the rate of dissolution as mentioned above is determined by dipping a silicon wafer having a resin film 1 ⁇ m thick in a 2.38% by weight aqueous tetramethylammonium hydroxide (TMAH) solution at 25° C. and determining the time (s) to reduce the film thickness to zero.
• TMAH aqueous tetramethylammonium hydroxide
• the phenol novolak resins of the invention can be synthetically produced by any process as far as the resulting resins satisfies the ratio of peak intensities and the weight average molecular weight (Mw) specified in the present invention. However, the following process is preferred, which can inhibit the formation of oligo-nuclear products of phenols and can efficiently synthetically produce the phenol novolak resin at low cost.
• the production process of a phenol novolak resin of the invention includes the following steps (a) to (d):
• a phenol and an aldehyde or ketone are put into an organic solvent and a reaction is performed in the presence of an acid catalyst.
• the residual phenol should be preferably added in the step (c) or in the step (d). Particularly preferably, the residual phenol should be added in the step (c) to enhance a decomposition reaction.
• the reaction is performed at a temperature of about 70° C. to 120° C. for about 3 to 20 hours.
• phenols for use in the polycondensation reaction in the step (a) when synthesizing the phenol novolak resin (1), preferred are those containing at least one selected from among phenols corresponding to the repeating units represented by the formulae (I) to (IV), i.e., m-cresol, p-cresol, 2,5-xylenol, and 3,5-xylenol; when synthesizing the phenol novolak resin (2), those containing at least one selected from among phenols corresponding to the repeating units represented by the formulae (I), (III), and (V), i.e., m-cresol, 2,5-xylenol, and 3,4-xylenol; and, when synthesizing the phenol novolak resin (3), those containing at least one selected from among phenols corresponding to the repeating units represented by the formulae (I), (II), and (VI), i.e., m-cresol,
• phenols include, but are not limited to, those conventionally used for the synthetic production of novolak resins for positive photoresist compositions.
• Such phenols include, for example, phenol, o-cresol, 2,3-xylenol, and other xylenols; m-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 3-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, and other alkyl-substituted phenols; p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol, m-propoxyphenol, and other alkoxy-
• the polycondensation product synthetically produced in the step (a) has a weight average molecular weight (Mw) in terms of polystyrene of preferably 1000 to 20000, and more preferably 2500 to 10000. If Mw is less than 1000, the target phenol novolak resin cannot be significantly produced, and if it exceeds 20000, the step (c) takes much time.
• Mw weight average molecular weight
• Aldehydes and ketones for use in the polycondensation reaction in the step (a) include, but are not limited to, those conventionally used for the synthetic production of novolak resins for positive photoresist compositions.
• aldehydes include, but are not limited to, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, butyraldehyde, trimethylacetaldehyde, acrolein (acrylaldehyde), crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, ⁇ -phenylpropylaldehyde, ⁇ -phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzal
• the ketones include, for example, acetone, methyl ethyl ketone, diethyl ketone, and diphenyl ketone. Each of these ketones may be used alone or in combination. Further, an appropriate combination of an aldehyde and a ketone can be employed.
• a phenol having a methylol group substituted on its nucleus can be used as the phenol.
• the aldehyde or ketone is not always required in the reaction.
• Acid catalysts for use in the condensation reaction of the phenol with the aldehyde or ketone include, for example, hydrochloric acid, sulfuric acid, phosphoric acid, and other inorganic acids, oxalic acid, formic acid, acetic acid, p-toluenesulfonic acid, and other organic acids, of which oxalic acid is specifically preferred.
• the acid catalyst should be preferably added in a proportion of about 0.001% to 10% by weight relative to the phenols.
• Organic solvents for use in the reaction include, but are not limited to, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, and other alcohols; diethylene glycol dimethyl ether, propylene glycol monopropyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, and other ethers; tetrahydrofuran, dioxane, and other cyclic ethers; acetone, methyl ethyl ketone, methyl isobutyl ketone, and other ketones; and ⁇ -butyrolactone, and other cyclic esters, of which ⁇ -butyrolactone is specifically preferred.
• the amount of the organic solvent is preferably about 50% to 1000% by weight relative to the phenols to yield appropriate cost and reaction rate.
• step (b) by-produced water, unreacted aldehyde and/or ketone are removed from a reaction system. By removing these substances from the reaction system, a decomposition reaction in the subsequent step (c) can be efficiently performed.
• the removal is preferably performed until water and other substances to be removed are completely removed from the reaction system.
• step (c) the polycondensation product produced in the step (a) is decomposed by action of an acid catalyst.
• the decomposition reaction should be preferably performed until the resulting decomposed product has a weight average molecular weight (Mw) in terms of polystyrene of about 200 to 2000, and specifically about 500 to 1500. If Mw is out of the above range, the target phenol novolak resin cannot be significantly synthetically produced in the subsequent step (d).
• Mw weight average molecular weight
• the acid catalyst for use in this step may be one remaining in the reaction system after the step (b), or one newly added to the reaction system.
• p-toluenesulfonic acid is preferred.
• the additional acid catalyst may be added such that the total amount of acid catalysts in the reaction system is preferably 0.01% to 20% by weight, and more preferably 1.0% to 10% by weight relative to the phenols.
• the reaction is performed at a temperature of about 80° C. to 150° C. for about 10 to 80 hours.
• the decomposition reaction of the polycondensation product in the step (c) swiftly proceeds in the presence of a phenol, and is preferably performed in the presence of such a phenol.
• the phenol may be one remaining in the reaction system as an unreacted monomer after the step (b) or one newly added to the reaction system. When the phenol is newly added, it must be selected from among phenols corresponding to constitutional units of the target phenol novolak resin.
• step (d) the polycondensation product decomposed in the step (c) is subjected to a polycondensation reaction with an aldehyde or ketone to thereby yield a high molecular weight product.
• the polycondensation product synthetically produced in the step (d) should preferably have a weight average molecular weight (Mw) in terms of polystyrene of 2000 to 20000, and more preferably 4000 to 10000. If Mw is less than 2000, film forming property and heat resistance may be deteriorated, and if it exceeds 20000, a highly sensitive positive photoresist composition cannot be significantly prepared.
• Mw weight average molecular weight
• Aldehydes and ketones for use in this step are not specifically limited, and those mentioned above can be used.
• the acid catalyst used in the step (c) remains in the reaction system, and an additional acid catalyst is not required in the step (d). However, an additional acid catalyst can be added if desired.
• the organic solvent used in the reaction in the step (a) remains in the reaction system, and an additional organic solvent is not required in the step (d), but it can be added if desired.
• the reaction is performed at a temperature of about 70° C. to 120° C. for about 3 to 20 hours.
• low molecular weight fractions of the resulting polycondensation product are removed by a conventional fractionation technique to thereby yield a phenol novolak resin having a weight average molecular weight (Mw) in terms of polystyrene of about 3000 to 20000.
• Mw weight average molecular weight
• the phenol novolak resin should preferably have Mw of about 4000 to 10000 for use in positive photoresist compositions, and a desired Mw can be obtained by conventionally known fractionation operations of high molecular weight fractions and low molecular weight fractions. For example, the following technique is advantageous.
• a solution of the novolak resin synthetically produced is dissolved in methyl amyl ketone (MAK) or a MAK-methanol mixture solvent, and the resulting solution is washed with water to remove the catalyst and unreacted compounds.
• MAK methyl amyl ketone
• MAK-methanol mixture solvent a poor solvent such as hexane or heptane, or a hexane-MAK or heptane-MAK mixture
• the resultant mixture is stirred and is then allowed to stand to separate a MAK layer containing high molecular weight fractions as a lower layer, and a poor solvent layer containing low molecular weight fractions as an upper layer.
• the phenol novolak resin obtained after the step (d) is low in content of oligo-nuclear products of phenols which have low reactivity, and the yield of the phenol novolak resin is high to thereby reduce production cost.
• the resulting phenol novolak resins (1) and (2) (specifically, Resins 1, 2, and 3) have a ratio of peak intensities of o-o/o-p/p-p in a resin structure detected by 13 C-NMR analysis which does not substantially vary in any molecular weight fraction and is constant.
• the resulting phenol novolak resins (1) and (2) have a resin composition not different in high molecular weight fractions and in low molecular weight fractions, in which the contents of o-o and o-p bonds relative to p-p bond are high.
• Peaks in the vicinity of 24.8 to 32.5 ppm, in the vicinity of 32.6 to 35.5 ppm, and in the vicinity of 35.6 to 39.0 ppm are respectively assigned to the peaks of o-o bond, of o-p bond, and of p-p bond.
• a positive photoresist composition of the present invention includes the phenol novolak resin and a 1,2-naphthoquinonediazide-group-containing compound.
• 1,2-naphthoquinonediazide-group-containing compounds for use in the present invention are not specifically limited and include those conventionally used as photosensitive components of positive photoresist compositions for i-line lithography.
• Preferred 1,2-naphthoquinonediazide-group-containing compounds are esters of a hydroxy compound with a naphthoquinone-1,2-diazidesulfonyl halide such as naphthoquinone-1,2-diazide-5-sulfonyl chloride, naphthoquinone-1,2-diazide-4-sulfonyl chloride, and naphthoquinone-1,2-diazide-6-sulfonyl chloride.
• Such hydroxy compounds for use in the above embodiment include, but are not limited to, the following compounds (i) to (iii):
• each of R 1 to R 8 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, or a cycloalkyl group; each of R 9 to R 11 is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Q is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or Q is combined with R 9 to form a cyclic ring having 3 to 6 carbon members, or a residue represented by the following formula (VIII); a and b each denote an integer of 1 to 3; d denotes an integer of 0 to 3; and n denotes an integer of 0 to 3:
• each of R 12 and R 13 is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, or a cycloalkyl group; and c denotes an integer of 1 to 3; and
• the ester can be prepared by subjecting, for example, the naphthoquinone-1,2-diazidesulfonyl halide and the hydroxy compound to a condensation reaction to completely or partially esterify these compounds.
• the condensation reaction is advantageously performed in an organic solvent in the presence of a basic condensing agent.
• organic solvents include, for example, dioxane, N-methylpyrrolidone, and dimethylacetamide; and such basic condensing agents include, for example, triethylamine, triethanolamine, an alkali carbonate, and an alkali hydrogencarbonate.
• the resulting ester should be preferably obtained by condensing 50% by mole or more, preferably 60% by more of, for example, a naphthoquinone-1,2-diazide-4(or -5)-sulfonyl halide relative to the total mole of hydroxyl groups in the hydroxy compound (i.e., the rate of esterification is 50% or more, and preferably 60% or more).
• the positive photoresist composition using such esters can yield higher definition.
• part of hydroxyl groups of the hydroxy compound may be esterified with a sulfonyl halide other than the naphthoquinonediazidesulfonyl halides.
• esters of a compound represented by the following formula (IX) and a naphthoquinonediazidesulfonyl halide with a hydroxy compound can be advantageously used:
• R 14 is an alkyl group, an alkyl group having at least one substituent, an alkenyl group, an aryl group, or an aryl group having at least one substituent; and X is a halogen atom.
• Such compounds represented by the formula (IX) include, but are not limited to, methanesulfonyl chloride, methanesulfonyl fluoride, ethanesulfonyl chloride, n-propanesulfonyl chloride, n-butanesulfonyl chloride, pentanesulfonyl chloride, dodecanesulfonyl chloride, and other alkane-sulfonyl halides each having 1 to 12 carbon atoms; chloromethylsulfonyl chloride, dichloromethylsulfonyl chloride, trichloromethylsulfonyl chloride, 2-chloroethylsulfonyl chloride, and other substituted alkane-sulfonyl halides each having 1 to 12 carbon atoms; ethylenesulfonyl chloride, 1-propene-1-sulfonyl chloride, and other alkene-sulfon
• naphthoquinone-1,2-diazidesulfonyl esters of bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-3,4-dihydoxyphenylmethane, 1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene, or bis[2,5-dimethyl-3-(2-hydroxy-5-methylbenzyl)-4-hydroxyphenyl]methane are preferred.
• the amount of the 1,2-naphthoquinonediazide-group-containing compound should preferably fall in a range of 10% to 60% by weight, and more preferably in a range of 20% to 50% by weight relative to the total weight of the phenol novolak resin and the following sensitizer added according to necessity. If the amount exceeds 60% by weight, the sensitivity may be deteriorated, and if it is less than 10% by weight, an image in exact accordance with a pattern cannot be obtained due to film reduction in unexposed portions or deterioration in definition.
• the positive photoresist composition of the invention may further comprise a sensitizer (an intensifier) according to necessity within a range not deteriorating the preferable performances of the composition.
• Sensitizers (intensifiers) for use in the invention include, but are not limited to, compounds conventionally used as sensitizers (intensifiers) of positive photoresist compositions.
• Such compounds include, for example, the compounds represented by the formula (VII), such as bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane, 1,4-bis[1-(3,5-dimethyl-4-hydroxyphenyl)isopropyl]benzene, 2,4-bis(3,5-dimethyl-4-hydroxyphenylmethyl)-6-methylphenol, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, 1-[1-(4-hydroxyphenyl) isopropyl]-4-
• 6-hydroxy-4a-(2,4-dihydroxyphenyl)-9-1′-spirocyclohexyl-1,2,3,4,4a,9a-hexahydroxanthene and 6-hydroxy-5-methyl-4a-(2,4-dihydroxy-3-methylphenyl)-9-1′-spirocyclohexyl-1,2,3,4,4a,9a-hexahydroxanthene can be used.
• the amount of the sensitizer is selected within a range of 5% to 50% by weight, and preferably 10% to 35% by weight, relative to the phenol novolak resin.
• the positive photoresist composition may further comprise various additives to further improve definition, exposure margin, and film residual rate.
• additives include, for example, p-toluenesulfonyl chloride (PTSC), 4,4′-bis(diethylamino)benzophenone, 1,4-bis[1-(2-methyl-4-hydroxy-5-cyclohexylphenyl)isopropyl]benzene, and 1,3-bis[1-(2-methyl-4-hydroxy-5-cyclohexylphenyl)isopropyl]benzene.
• PTSC p-toluenesulfonyl chloride
• 4,4′-bis(diethylamino)benzophenone 4,4′-bis(diethylamino)benzophenone
• 1,4-bis[1-(2-methyl-4-hydroxy-5-cyclohexylphenyl)isopropyl]benzene 1,3-bis[1-(2-methyl-4-hydroxy-5-cyclo
• the positive photoresist composition of the present invention may further comprise any of compatible additives including, for example, ultraviolet absorbents for inhibition of halation and surfactants for prevention of striation within ranges not adversely affecting the objects of the invention.
• ultraviolet absorbents include, for example, 4-dimethylamino-2′,4′-dihydroxybenzophenone, 5-amino-3-methyl-1-phenyl-4-(4-hydroxyphenylazo)pyrazole, 4-dimethylamino-4′-hydroxyazobenzene, 4-diethylamino-4′-ethoxyazobenzene, 4,4′-diethylaminoazobenzene, and curcumin.
• the surfactants include, but are not limited to, Fluorade FC-430 and FC-431 (trade names, manufactured by Sumitomo 3M Ltd., Japan), F-TOP EF122A, EF122B, EF122C, and EF126 (trade names, manufactured by Tochem Products Ltd., Japan) and other fluorine-containing surfactants.
• the positive photoresist composition of the invention is preferably used as a solution obtained by dissolving each of the above-specified ingredients in an appropriate solvent.
• solvents include those conventionally used in positive photoresist compositions, such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, and other ketones; ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monoacetate, propylene glycol monoacetate, diethylene glycol monoacetate, or monomethyl ethers, monoethyl ethers, monopropyl ethers, monobutyl ethers or monophenyl ethers thereof, and other polyhydric alcohols and derivatives thereof; dioxane, and other cyclic ethers; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, eth
• Each of these solvents can be used alone or in combination.
• these solvents typically preferred are acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, and other ketones; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, and other esters.
• the positive photoresist composition of the present invention may be preferably used, for example, in the following manner.
• Each of the phenol novolak resin and the 1,2-naphthoquinonediazide-group-containing compound, and other ingredients added according to necessity is dissolved in an appropriate solvent as mentioned above to yield a coating solution; the coating solution is then applied, using a spinner or the like, onto a substrate such as a silicon wafer or a substrate on which an antireflection coating has been formed, and is then dried to form a photosensitive layer; next, the photosensitive layer is irradiated and is exposed with an ultraviolet ray source such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, an arc lamp, or a xenon lamp, through a desired mask pattern, or irradiated with a scanning electron beam; and the exposed portions of the film are then dissolved and removed by dipping the substrate in a developer solution, for example, an alkaline
• the solution was dissolved in 500 g of methyl amyl ketone (MAK), and was washed with water to remove the acid catalyst, unreacted materials, and low molecular weight substances.
• MAK methyl amyl ketone
• the resulting product was adjusted to 600 g of a 15% by weight solution in MAK, and to this solution, 585 g of n-heptane was added, and the mixture was stirred, was allowed to stand, and the lower phase (MAK phase) was extracted to thereby yield a phenol novolak resin (A1) having Mw of 8440 and a rate of dissolution of 0.003 ⁇ m/s.
• the yield calculated from the amount of material phenols was 53%.
• the solution was dissolved in 500 g of methyl amyl ketone (MAK), and was washed with water to remove the acid catalyst, unreacted materials, and low molecular weight substances.
• MAK methyl amyl ketone
• the resulting product was adjusted to 600 g of a 15% by weight solution in MAK, and to this solution, 630 g of n-heptane was added, and the mixture was stirred, was allowed to stand, and the lower phase (MAK phase) was extracted to thereby yield a phenol novolak resin (D1) having Mw of 8660 and a rate of dissolution of 0.004 Rm/s.
• Table 1 show that the phenol novolak resins prepared according to the processes described in Preparation Examples 1 to 4 each had a ratio of peak intensities of ortho-ortho bond/ortho-para bond/para-para bond not substantially varying each molecular weight fraction in the resin structure detected by 13 C-NMR analysis.
• Table 2 shows that the phenol novolak resins prepared according to processes described in Comparative Preparation Examples 1 to 5 (other than 4) had a ratio of peak intensities of ortho-ortho bond/ortho-para bond/para-para bond significantly varying in each molecular weight fraction in the resin structure detected by 13 C-NMR analysis.
• Coating composition 1 of a positive photoresist composition was prepared by mixing 100 parts by weight of the phenol novolak resin (A1) prepared in Preparation Example 1, 35 parts by weight of a 1,2-naphthoquinonediazide-group-containing compound, 28 parts by weight of a sensitizer, and 420 parts by weight of a solvent.
• the ingredients are as follows.
• Sensitizer 1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene
• Coating composition 2 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (B1) prepared in Preparation Example 2 was used instead of the phenol novolak resin (A1).
• Coating composition 3 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (D1) prepared in Preparation Example 4 was used instead of the phenol novolak resin (A1).
• Coating composition 4 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (E1) prepared in Preparation Example 5 was used instead of the phenol novolak resin (A1).
• Coating composition 5 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (D2) prepared in Comparative Preparation Example 4 was used instead of the phenol novolak resin (A1).
• Coating composition 6 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (A2) prepared in Comparative Preparation Example 1 was used instead of the phenol novolak resin (A1).
• Coating composition 7 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (B2) prepared in Comparative Preparation Example 2 was used instead of the phenol novolak resin (A1).
• Coating composition 8 of a positive photoresist composition was prepared in the same manner as in Example 1, except that the phenol novolak resin (E2) prepared in Comparative Preparation Example 5 was used instead of the phenol novolak resin (A1).
• a sample was applied onto a silicon wafer using a spinner, and was dried on a hot plate at 90° C. for 90 sec. to form a resist film having a thickness of 1.25 ⁇ m.
• the film was then post-exposure baked (PEB) at 110° C. for 90 sec.; was subjected to developing in a 2.38% by weight tetramethylammonium hydroxide aqueous solution at 23° C.
• PEB post-exposure baked
• the sensitivity was defined as the exposure time period (Eop) (ms) to exactly reproduce set dimensions of the mask pattern (0.35- ⁇ m line width with line-and-space (L&S) width of 1:1).
• the definition was defined as the critical definition at an exposure which reproduced a mask pattern corresponding to 0.35- ⁇ m L&S.
• the obtained resist pattern was subjected to an SEM (scanning electron microscope) photographic observation. Based upon the SEM photograph, the focal depth range property on dense pattern was defined as the maximum value ( ⁇ m) of the focal shift (defocus) to obtain a 0.35- ⁇ m dense pattern with L&S of 1:1 within a variation of ⁇ 10% of the set dimensions.
• the obtained resist pattern was subjected to an SEM photographic observation. Based upon the SEM photograph, the focal depth range property on isolation pattern was defined as the maximum value (am) of the focal shift (defocus) to obtain a 0.35- ⁇ m isolation pattern within a variation of ⁇ 10% of the set dimensions (0.35 ⁇ m).
• Table 3 shows that the positive photoresist compositions of Examples 1 to 5 using the invented novolak resins (A1, B1, D1, E1 and D2) are satisfactory in focal depth range properties in the formation of dense pattern and isolation pattern of not more than 0.35 ⁇ m, and have satisfactory sensitivity and definition. Furthermore, the novolak resin El has a specific ratio of peak intensity and a specific phenol constitutional units and has a ratio of peak intensities varying in each molecular weight fraction.
• Table 4 shows that the positive photoresist compositions of Examples 1 to 5 can form both dense pattern and isolation pattern with good shapes, as compared with the positive photoresist compositions of Comparative Examples 1 to 3.
• Example 3 it is found that a positive photoresist composition of Example 3 using a novolak resin Dl which has a specific ratio of peak intensity has a good pattern shape.
• the present invention provides positive photoresist compositions that can form both dense pattern and isolation pattern with good phases and have satisfactory sensitivity, definition, and focal depth range properties even in the formation of a fine resist pattern of not more than 0.35 ⁇ m.
• the present invention provides phenol novolak resins that are advantageous for the preparation of the positive photoresist compositions.
• the invention provides phenol novolak resins which include minimized oligo-nuclear products of phenols and have uniform resin composition both in high molecular weight fractions and in low molecular weight fractions in the production of a phenol novolak resin using two or more types of phenols as materials, and a process for synthetically producing the phenol novolak resins.

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• 2001
  • 2001-02-26 KR KR1020010009714A patent/KR100709520B1/ko active IP Right Grant
  • 2001-02-28 US US09/793,958 patent/US20010024762A1/en not_active Abandoned
• 2004
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