Positive-working photoresist composition

Abstract: A positive-working photoresist composition is disclosed, which comprises (1) a light-sensitive material obtained by reacting a polyhydroxy compound containing at least one group represented by the following general formula (I) per molecule with at least one of 1,2- naphthoquinonediazide-5-sulfonyl chloride and 1,2-naphthoquinonediazide-4-sulfonyl chloride, and (2) an alkali-soluble novolak resin: wherein R₁ and R₂ each represents a hydrogen atom or a C₁-C₄ straight or branched alkyl or alkoxy group, provided that R₁ and R₂ do not represent hydrogen atoms at the same time; and X represents a divalent organic group.

Description: This invention relates to a positive-working photoresist composition which responds to radiation and, more particularly, to a photoresist composition having a high resolving power and a high sensitivity and being capable of forming micro-patterns with good profiles. As positive-working photoresist compositions, those compositions which contain an alkali-soluble resin and a light-sensitive naphthoquinonediazide compound are generally used. For example, compositions containing a novolak phenol resin and a naphthoquinone diazide-substituted compound are described in US-A-3666473, 4115128 and 4173470; JP-A-57-63526; and in earlier application EP-A-341608. Examples of a "novolak resin composed of cresol-formaldehyde/trihydroxybenzophenone-1,2-naphthoquinonediazidosulfonic acid esters" are described by L.F. Thompson, Introduction to Microlithography (published by ACS, No. 219), pp. 112-121. The novolak resin used as a binder is particularly useful since it is soluble in an alkali aqueous solution without swelling and shows a high resistance particularly against plasma etching when using an image formed therein as a mask or etching. The naphthoquinonediazide compound used as a light-sensitive material decreases alkali solubility of the novolak resin and, when decomposed by irradiation with light, produces an alkali-soluble substance and actually increases the alkali solubility of the novolak resin. The naphthoquinonediazide compound is particularly useful because of this great change in its properties induced by light. Many positive-working photoresists containing the novolak resin and the naphthoquinonediazide light-sensitive material have so far been developed and put into practice in view of the above-described advantages, and sufficient results have been obtained in forming lines with a width of about 1.5 µm to about 2 µm. However, the degree of integration of integrated circuits is increasing more and more and, in manufacturing semiconductor bases such as VLSI, formation of ultramicro-patterns with a line width as narrow as 1 µm is required. For such uses, the conventional positive photoresists described above are insufficient, and photoresists having a high resolving power, an ability to accurately reproduce a pattern of an exposure mask, and a high sensitivity for attaining high productivity are required. An object of the present invention is to provide a positive-working photoresist composition having the following advantages in manufacture of semiconductor devices: (1) shows a high resolving power; (2) is capable of accurately reproducing a mask dimension of photomask lines with a wide range of line widths; (3) is capable of forming a resist pattern as narrow as 1 µm in line width having a sectional profile with a high aspect ratio; (4) is capable of forming a pattern having approximately vertical side walls in the pattern profile; (5) has a broad development latitude; and (6) provides a resist image having an excellent heat resistance. As a result of intensive investigations with the above-described properties in mind, the present inventors have found that this and other objects can be attained by a positive-working photoresist composition as defined in Claim 1. The light-sensitive material (1) is obtained by reacting a polyhydroxy compound containing at least one group represented by the following general formula (I) or I' per molecule with at least one of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 1,2-naphthoquinonediazido-4-sulfonyl chloride: wherein R 1 , R 2 , R' 1 and R' 2 are defined in claim 1. In the general formula (I) or (I'), specific examples of the alkyl group are methyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl groups, and specific examples of the alkoxy group include methoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, t-butoxy groups. The linking group X in the general formula (I) or (I') is defined in claim 1. By reacting a polyhydroxy compound containing at least one group represented by the general formula (I) or (I') per molecule with 1,2-naphthoquinonediazido-5-sulfonyl chloride and/or 1,2-naphthoquinonediazido-4-sulfonyl chloride there is obtained a light-sensitive material represented by the general formulae (II) to (IX) below. The examples of the polyhydroxy compounds are polyhydroxy compounds represented by the general formulae (II') to (IX') described hereinafter In the above general formulae (II) to (IX), R 1 ' and R 2 ' each represents a C 1 -C 4 straight or branched alkyl or alkoxy group; R 1 and R 2 each represents a hydrogen atom, or a C 1 -C 4 straight or branched alkyl or alkoxy group, provided that R 1 and R 2 do not represent hydrogen atoms at the same time; X represents a C 1 -C 4 straight or branched alkylene group, -S- or -O-, more preferably a C 1 -C 4 straight or branched alkylene group, and most preferably a C 1 -C 4 straight or branched alkylene group); R represents -H, (which may be the same or different); R 3 to R 20 , which may be the same or different, each represents -H, -OH, a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, a substituted or unsubstituted C 2 -C 15 acyl group, a substituted or unsubstituted C 2 -C 15 acyloxy group, or provided that and/or within one molecule of the light-sensitive material; a is 1 to 5, provided that when a is 2 to 5, the R 3 groups may be the same or different and at least one of the R 3 groups is a group other than -H and an alkyl group; R 21 to R 26 each represents -H, -OH, -COOH, -CN, a halogen atom, -COOR 27 , -R 28 -COOH, -R 29 -COOR 30 (wherein R 27 and R 30 each represents a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, and R 28 and R 29 each represents a substituted or unsubstituted C 1 -C 8 alkylene group or a substituted or unsubstituted C 6 -C 15 arylene group), a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, or a substituted or unsubstituted C 6 -C 15 aralkyl group; Y represents or -SO 2 -; Z represents an oxygen atom or a single bond; and b to u represent real numbers satisfying the following conditions: 1≤l≤4, 0≤m, n≤4, 0≤b to k, and o to u≤5. Among the light-sensitive materials of formula (II) the following are excluded from the present invention: (1) Materials of formula (II) having a hydroxyl group or a 1,2-naphthoquinonediazide-5- or -4-sulfonyloxy group in an ortho position to X and wherein l = 1 and X represents -CR 31 R 32 , wherein (i) R 31 and R 32 , the same or different, represent alkyl, alkenyl, cycloalkyl, alkoxy or aryl, or wherein (ii) at least one of R 31 and R 32 is hydrogen and an alkyl or aryl group is present at the ortho position to said hydroxyl group in ortho position to X; and (2) Materials of formula (II) having a hydroxyl group or a 1,2-naphthoquinonediazide-5- or -4-sulfonyloxy group R 3 in para position to X and two further groups R 3 selected from -H and alkyl in other positions, with the proviso that these are not simultanously -H, and wherein X represents straight-chain or branched C 1 -C 4 alkylene or -S-, R 1 ' and R 2 ' each represents a C 1 -C 4 alkyl group, R is -H or a 1,2-naphthoquinonediazide-5- or -4-sulfonyl group in para position to X, and l = 1. The light-sensitive materials represented by the general formulae (II) to (IX) can be obtained by reacting the polyhydroxy compounds represented by the following general formulae (II') to (IX') with 1,2-naphthoquinonediazide-5-sulfonyl chloride and/or 1,2-naphtoquinonediazide-4-sulfonyl chloride. In the above general formulae (II') to (IX'), R 1 ' and R 2 ' each represents a C 1 -C 4 straight or branched alkyl or alkoxy group; R 1 and R 2 each represents a hydrogen atom, or a C 1 -C 4 straight or branched alkyl or alkoxy group, provided that R 1 and R 2 do not represent hydrogen atoms at the same time; X represents a C 1 -C 4 straight or branched alkylene group, -S- or -O-, more preferably a C 1 -C 4 straight or branched alkylene group, and most preferably a C 1 -C 4 straight or branched alkylene group); R 3 ' to R 20 ', which may be the same or different, each represents -H, -OH, a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, a substituted or unsubstituted C 2 -C 15 acyl group, or a substituted or unsubstituted acyloxy group, provided that 1≤-OH≤9 per molecule; a is 1 to 5, provided that when a is 2 to 5, the R 3 groups may be the same or different and at least one of the R 3 groups is a group other than -H and an alkyl group; R 21 to R 26 each represents -H, -OH, -COOH, -CN, a halogen atom, -COOR 27 , -R 28 -COOH, -R 29 -COOR 30 (wherein R 27 and R 30 each represents a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, and R 28 and R 29 each represents a substituted or unsubstituted C 1 -C 8 alkylene group or a substituted or unsubstituted C 6 -C 15 arylene group), a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, or a substituted or unsubstituted C 6 -C 15 aralkyl group; Y represents or -SO 2 -; Z represents an oxygen atom or a single bond; and b to u represent real numbers satisfying the following conditions: 1≤l≤4, 0≤m, n≤4, 0≤b to k, and o to u≤5. With respect to the above formula (II') the same proviso as in the case of the above formula (II) applies. The polyhydroxy compounds (II') to (IX') can be obtained by introducing the group represented by general formula (I) or I' into the starting polyhydroxy compounds according to the reactions illustrated hereinafter. In this case, where the starting polyhydroxy compounds have a plurality of reactive sites, the products are obtained as a mixture which may also be used in the present invention. The term "starting polyhydroxy compound" as used herein and in the following reaction schemes means the compounds corresponding to formulae (II') to (IX') but containing no group represented by formula (I). The esterification reaction between the polyhydroxy compound represented by one of the general formulae (II') to (IX') and 1,2-naphthoquinonediazido-5-sulfonyl chloride and/or 1,2-naphthoquinonediazido-4-sulfonyl chloride is conducted in a conventional manner as described in, for example, U.S. Patent 4,639,406. That is, predetermined amounts of the polyhydroxy compound represented by one of the general formulae (II') to (IX'), 1,2-naphthoquinonediazido-5-sulfonyl chloride and/or 1,2-naphthoquinonediazido-4-sulfonyl chloride, and a solvent such as dioxane, acetone, methyl ethyl ketone or N-methylpyrrolidone were charged in a flask, and a basic catalyst such as sodium hydroxide, sodium carbonate, sodium hydrogencarbonate or triethylamine was dropwise added thereto to conduct the condensation reaction. The resulting product is washed with water, purified, and dried. Light-sensitive materials represented by the general formulae (II) to (IX) can be obtained in the above-described manner. As a result of the above-described esterification reaction, there is obtained a mixture of compounds different from each other in esterification number and esterification position. Therefore, the term "esterification ratio" as used herein in the present invention is defined as an average value of the mixture. The alkali-soluble novolak resin may be obtained by addition condensation between 1 mol of a phenol and 0.6 to 1.0 mol of an aldehyde in the presence of an acidic catalyst. Examples of the phenol which can be used include phenol, o-cresol, m-cresol, p-cresol, xylenol, naphthol, etc., either independently or as a combination of two or more. Examples of the aldehyde which can be used include formaldehyde, para-formaldehyde, acetaldehyde, halogenated acetaldehyde (e.g., chloro- or bromo-), furfural. Examples of the acidic catalyst which can be used include hydrochloric acid, sulfuric acid, formic acid, oxalic acid, acetic acid. The thus-obtained novolak resin having a molecular weight of 1,000 to 50,000 is alkali-soluble. As to the ratio of the light-sensitive material to the alkali-soluble novolak resin to be used in the present invention, 5 to 100 parts by weight, preferably 7 to 40 parts by weight, of the light-sensitive material is used per 100 parts of the novolak resin. If the amount of the light-sensitive substance is less than 5 parts by weight, there results a seriously decreased film-remaining ratio, whereas if the amount used is more than 100 parts by weight, there result a decreased sensitivity and a decreased solubility in the solvent. In the present invention, the aforesaid light-sensitive material may be the primary light-sensitive material used, but, if necessary, ordinary light-sensitive materials such as ester compounds formed between 2,3,4- trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, etc. and 1,2-naphthoquinonediazido-5-sulfonyl chloride and/or 1, 2-naphthoquinonediazido-4-sulfonyl chloride may be used together with the light-sensitive material of the present invention. In this case, these ordinary light-sensitive materials may be used in an amount of up to 100 parts by weight, preferably up to 30 parts by weight, per 100 parts by weight of the light-sensitive material of the present invention represented by, for example, the foregoing general formulae (II) to (IX). The composition of the present invention may further contain a polyhydroxy compound for promoting dissolution into a developer. Preferable examples of such polyhydroxy compounds include phenols, resorcin, phloroglucin, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,3',4',5'-hexahydroxybenzophenone, and acetone-pyrogallol condensate resin. Solvents for dissolving the light-sensitive material and the alkali-soluble novolak resin in accordance with the present invention include illustrated ketones such as methyl ethyl ketone and cyclohexanone, alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ethers such as dioxane and ethylene glycol dimethyl ether, cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate, fatty acid esters such as methyl lactate, ethyl lactate and butyl acetate, halogenated hydrocarbons such as 1,1,2-trichloroethylene, and highly polar solvents such as dimethylacetamide, N-methylpyrrolidone, dimethylformamide and dimethylsulfoxide. These solvents may be used either alone or in combination of two or more of them. The positive-working photoresist composition of the present invention may contain, if necessary, a dye, a plasticizer, an adhesion aid, and/or a surfactant. Specific examples of the dye include Methyl Violet, Crystal Violet, and Malachite Green; specific examples of the plasticizers include stearic acid, acetal resin, phenoxy resin and alkyd resin; specific examples of the adhesion aid include hexamethyldisilazane and chloromethylsilane; and specific examples of the surfactant include nonylphenoxypoly(ethyleneoxy)ethanol and octylphenoxypoly(ethyleneoxy)ethanol. The positive-working photoresist composition of the present invention can be coated on a base board such as a semiconductor wafer, a glass plate, a ceramic plate or a metal plate in a thickness of 0.5 to 0.3 µm according to the spin-coating method or the rollercoating method. Then, the coated layer is heated and dried, exposed to UV rays or the like through an exposure mask to print a circuit pattern thereon, and then developed to obtain a positive image. Further, patternwise etching using this positive image as a mask enables patternwise processing. Typical fields for applying the composition include a process of manufacturing semiconductors such as IC, a process of manufacturing circuit bases for liquid crystal, thermal head or the like, and other photofabrication processes as described in U.S. Patent 4,639,406. A good resist can be obtained by coating the above-described positive-working photoresist composition on a substrate for use in manufacture of fine integrated circuit elements (e.g., silicon/silicon dioxide coating) according to a proper coating method using, for example, a spinner or a coater, exposing the coated composition through a predetermined mask, and then developing it. As a developing solution for the positive photoresist composition of the present invention, there may be used aqueous solutions of alkalis such as inorganic alkalis (e.g., sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate and aqueous ammonia), primary amines (e.g., ethylamine and n-propylamine), secondary amines (e.g., diethylamine and di-n-butylamine), tertiary amines (e.g., triethylamine and methyldiethylamine), alcohol-amines (e.g., dimethylethanolamine and triethanolamine), quaternary ammonium salts (e.g., tetramethylammoium hydroxide and tetraethylammonium hydroxide), and cyclic amines(e.g., pyrrole and piperidine). The above-described aqueous alkali solutions may further contain proper amounts of alcohols and surfactants. The positive-working photoresist of the present invention is excellent in resolving power, reproduction fidelity, profile pattern of resist pattern, development latitude, heat resistance and storage stability of the resist. The present invention is now illustrated in greater detail by reference to the following examples. Unless otherwise indicated, all percents are by weight. EXAMPLES 1 TO 20 AND COMPARATIVE EXAMPLES 21 TO 25 (1) Synthesis of Light-Sensitive Material (a): 10 g of the following compound (a'), 31.0 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 350 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=12.3 g/50 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1600 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 34.0 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (a'). (3) Synthesis of Light-Sensitive Material (c): 10 g of the following compound (c'), 23.4 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 260 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=9.3 g/40 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1200 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 28.2 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (c'). (4) Synthesis of Light-Sensitive Material (d): 10 g of the following compound (d'), 28.0 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 320 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=11.1 g/45 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 31.4 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (d') (5) Synthesis of Light-Sensitive Material (e): 10 g of the following compound (e'), 20.5 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 230 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=8.1 g/33 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1100 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 25.4 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (e'). (6) Synthesis of Light-Sensitive Material (f): 10 g of the aforesaid compound (e'), 34.1 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 390 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of 4-dimethylaminopyridine/acetone (=16.3 g/250 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 3000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 35.7 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (e'). (7) Synthesis of Light-Sensitive Material (g): 10 g of the aforesaid compound (e'), 34.1 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 390 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of 4-dimethylaminopyridine/acetone (=16.3 g/250 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 3000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 37.0 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (e'). (8) Synthesis of Light-Sensitive Material (h): 10 g of the following compound (h'), 26.4 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of 4-dimethylaminopyridine/acetone (=12.6 g/190 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 2500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 30.6 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (h'). (9) Synthesis of Light-Sensitive Material (i): 10 g of the following compound (i'), 13.7 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 160 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=5.4 g/25 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 19.4 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (i'). (10) Synthesis of Light-Sensitive Material (j): 10 g of the following compound (j'), 41.6 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 470 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=16.5 g/67 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 3000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 42.8 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (j'). (11) Synthesis of Light-Sensitive Material (k): 10 g of the following compound (k'), 29.5 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 330 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=11.7 g/50 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 2000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 33.6 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (k'). (12) Synthesis of Light-Sensitive Material (ℓ): 10 g of the following compound (ℓ'), 15.8 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 200 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=6.2 g/30 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 21.4 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (ℓ'). (13) Synthesis of Light-Sensitive Material (m): 10 g of the following compound (m'), 27.2 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=10.8 g/45 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1800 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 32.0 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (m'). (14) Synthesis of Light-Sensitive Material (n): 10 g of the following compound (n'), 18.1 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 210 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=7.2 g/30 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 23.0 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (n'). (15) Synthesis of Light-Sensitive Material (o): 10 g of the following compound (o'), 26.6 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=10.5 g/45 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1400 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 31.1 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (o'). (16) Synthesis of Light-Sensitive Material (p): 10 g of the following compound (p'), 38.0 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 430 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=15.0 g/60 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 2000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 40.8 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (p'). (17) Synthesis of Light-Sensitive Material (q): 10 g of the following compound (q'), 27.3 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 310 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=10.8 g/45 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 30.8 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (q'). (18) Synthesis of Light-Sensitive Material (r): 10 g of the following compound (r'), 19.0 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 220 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=7.5 g/30 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 23.8 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (r'). (19) Synthesis of Light-Sensitive Material (s): 10 g of the following compound (s'), 25.4 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=10.0 g/40 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 29.8 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (s'). (20) Synthesis of Light-Sensitive Material (t): 10 g of the following compound (t'), 34.1 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 400 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of 4-dimethylaminopyridine/acetone (=16.3 g/250 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 3000 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 37.5 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (t'). (21) Synthesis of Light-Sensitive Material (u) (Comparative Example 1): 7.85 g of 2,3,4,4'-tetrahydroxybenzophenone (u') of the following formula (u'), 30 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=11.3 g/30 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 27.5 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of 2,3,4,4'-tetrahydroxybenzophenone (u'). (22) Synthesis of Light-Sensitive Material (v) (Comparative Example 2): 10 g of the following compound (v'), 31.6 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 350 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=12.5 g/50 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1600 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 34.1 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (v'). (23) Synthesis of Light-Sensitive Material (w) (Comparative Example 3): 10 g of the following compound (w'), 39.4 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 450 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=15.6 g/70 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 2500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 41.4 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (w'). (24) Synthesis of Light-Sensitive Material (x) (Comparative Example 4): 10 g of the following compound (x'), 26.8 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 300 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=10.6 g/45 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 1400 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 30.5 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (x'). (25) Synthesis of Light-Sensitive Material (y) (Comparative Example 5): 10 g of the following compound (y'), 43.8 g of 1,2-naphthoquinonediazido-5-sulfonyl chloride and 500 ml of acetone were charged in a three-necked flask to prepare a uniform solution. Thereafter, a mixed solution of triethylamine/acetone (=17.3 g/70 ml) was gradually added dropwise thereto, and the reaction was conducted at 25°C for 3 hours. The reaction mixture was then poured into 2500 ml of a 1% hydrochloric acid aqueous solution. The precipitate formed was collected by filtration, washed with water, and dried (at 40°C) to obtain 45.2 g of 1,2-naphthoquinonediazido-5-sulfonic acid ester of the compound (y'). (26) Synthesis of novolak resin 40 g of m-cresol, 60 g of p-cresol, 49.5 g of a 37% formaldehyde aqueous solution, and 0.05 g of oxalic acid were charged in a three-necked flask, and the mixture was heated to 100°C under stirring to react for 7 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and the pressure was reduced to 30 mmHg. Thereafter, the mixture was gradually heated to 150°C, and water and unreacted monomer were removed. The thus obtained novolak resin had a weight-average molecular weight (polystyrene-reduced value) of 7,000. (27) Preparation of positive-working photoresists and evaluation thereof: 1.10 g of each of the above-described light-sensitive materials (a) to (y) obtained in (1) to (25) and 5 g of the cresol novolak resin (molecular weight: 7,000) obtained in (26) described above were dissolved in 18 g of ethyl cellosolve acetate. The resulting solution was filtered through a 0.2-µm microfilter to prepare photoresist compositions. Each of the photoresists was coated on a silicon wafer using a spinner, and dried at 110°C for 30 minutes in a convection oven in a nitrogenous atmosphere to form a 1.2-µm thick resist film. The thus formed films were exposed using a reduction projection optical printer (NSR 1505 made by Nikon Co., Ltd.), developed for 1 minute in a 2.38% aqueous solution of tetramethylammonium hydroxide, then washed with water for 30 minutes and dried. Resist patterns of the silicon wafers thus obtained were observed under a scanning electron microscope to evaluate the resists. Results thus obtained are shown in Table 1. Sensitivity is defined as a reciprocal of an exposure amount capable of reproducing a 1.0-µm mask pattern, and is presented as relative values taking the sensitivity of Comparative Example 1 as 1.0. Film-remaining ratio is presented in terms of percentage of remaining film in an unexposed portion after development based on before development. Resolving power represents a limiting resolving power in an exposure amount capable of reproducing a 1.0-µm mask pattern. Heat resistant is presented in terms of a temperature at which a patterned resist formed on a silicon wafer is not deformed after baking for 30 minutes in a convection oven. Profile of the resist is presented in terms of an angle () formed by the resist wall in the 1.0-µm resist pattern section with the plane of silicon wafer. As can be seen from above, resists using the light-sensitive materials (a) to (t) in accordance with the present invention showed particularly excellent resolving power and resist profile. The light-sensitive materials in accordance with the present invention also possess excellent solubility in ethyl cellosolve acetate. The resist compositions using these light-sensitive materials of the present invention suffered formation of no precipitates even after being allowed to stand for 30 days at 40°C, whereas the resist compositions using the light-sensitive materials (u), (v) and (x) of Comparative Examples suffered formation of precipitates after being allowed to stand under the same conditions. The term "1,2-naphthoquinone diazide" refers to the 2-diazonaphthoquinone-(1,2) structure.

Claims: A positive-working photoresist composition which contains an admixture of (1) a light-sensitive material selected from those represented by any of formulae (II) to (IX) and (2) and an alkali-soluble novolak resin: wherein R 1 ' and R 2 ' each represents a C 1 -C 4 straight or branched alkyl or alkoxy group; R 1 and R 2 each represents a hydrogen atom or a C 1 -C 4 straight or branched alkyl or alkoxy group, provided that R 1 and R 2 do not represent hydrogen atoms at the same time; X is selected from straight-chain or branched C 1 -C 4 alkylene, -CO-. -COO- -CS-, -NHCO-, -NHCOO-, -S- and -O-; R represents -H, which may be the same or different; R 3 to R 20 , which may be the same or different, each represents -H, -OH, a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, a substituted or unsubstituted C 2 -C 15 acyl group, a substituted or unsubstituted C 2 -C 15 acyloxy group, provided that and/or within one molecule of the light-sensitive material; a is 1 to 5, provided that when a is 2 to 5, the R 3 groups may be the same or different and at least one of the R 3 groups is a group other than -H and an alkyl group; R 21 to R 26 each represents -H, -OH, -COOH, -CN, a halogen atom, -COOR 27 , -R 28 -COOH, -R 29 -COOR 30 (wherein R 27 and R 30 each represents a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 6 -C 15 aryl group, a substituted or unsubstituted C 6 -C 15 aralkyl group, and R 28 and R 29 each represents a substituted or unsubstituted C 1 -C 8 alkylene group or a substituted or unsubstituted C 6 -C 15 arylene group), a substituted or unsubstituted C 1 -C 8 alkyl group, a substituted or unsubstituted C 1 -C 8 alkoxy group, or a substituted or unsubstituted C 6 -C 15 aralkyl group; Y represents or SO 2 -; Z represents an oxygen atom or a single bond; and b to u represent real numbers satisfying the following conditions: 1 ≤ l ≤ 4, 0 ≤ m, n ≤ 4, 0 ≤ b to k, and o to u ≤ 5; the substituents of the foregoing substituted groups being selected from alkoxy, aryl, hydroxyl, carboxyl, amino, nitro, silyl and cyano groups; provided that among the light-sensitive materials of formula (II) the following are excluded: (1) materials of formula (II) having a hydroxyl group or a 1,2-naphthoquinonediazide-5- or -4-sulfonyloxy group in an ortho position to X and wherein 1 = 1 and X represents -CR 31 R 32 , wherein (i) R 31 and R 32 , the same or different, represent alkyl, alkenyl, cycloalkyl, alkoxy or aryl, or wherein (ii) at least one of R 31 and R 32 is hydrogen and an alkyl or aryl group is present at the ortho position to said hydroxyl group in ortho position to X; and (2) materials of formula (II) having a hydroxyl group or a 1,2-naphthoquinonediazide-5- or -4-sulfonyloxy group R 3 in para position to X and two further groups R 3 selected from -H and alkyl in other positions, with the proviso that these are not simultanously -H, and wherein X represents straight-chain or branched C 1 -C 4 alkylene or -S-, R 1 ' and R 2 ' each represents a C 1 -C 4 alkyl group, R is -H or a 1,2-naphthoquinonediazide-5- or -4-sulfonyl group in para position to X, and l = 1. The positive-working photoresist composition of claim 1, wherein both R 1 and R 2 represent C 1 to C 4 straight or branched alkyl or alkoxy groups. The positive-working photoresist composition of claim 1 or 2, wherein X represents a C 1 to C 4 straight or branched alkylene group. The positive-working photoresist composition of any one of claims 1-3, wherein the polyhydroxy compound is reacted with 1,2-naphthoquinonediazide-5-sulfonyl chloride. The positive-working photoresist composition of any one of claims 1-3, wherein the polyhydroxy compound is reacted with 1,2-naphthoquinonediazide-4-sulfonyl chloride.

Inventors: KOKUBO TADAYOSHI, SAKAGUCHI SHINJI, UENISHI KAZUYA, KOKUBO, TADAYOSHI,                             ., SAKAGUCHI, SHINJI,                             ., UENISHI, KAZUYA,, KOKUBO, TADAYOSHI, C/O FUJI PHOTO FILM CO., LTD., SAKAGUCHI, SHINJI, C/O FUJI PHOTO FILM CO., LTD., UENISHI, KAZUYA, C/O FUJI PHOTO FILM CO., LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1990
Main classification: G03F7
IPC codes: H01L21, G03F7