JPH04251257A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To provide a positive type photoresist having high sensitivity, superior resolving power and developability, giving a resist pattern having a fine shape and superior heat resistance and useful to produce a semiconductor device, etc. CONSTITUTION:When a positive type photoresist compsn. contg. a quinonediazido compd. and alkali-soluble novolak resin is prepd., the amt. of a dimer contained in the novolak resin is regulated to 2-6% of the amt. of the novolak resin (expressed in terms of the areal ratio in a pattern formed by gel permeation chromatography) and the amt. of a trimer is regulated to 10-20%. The ratio of the trimer to the dimer is 2.0-10.0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positive photoresist that is sensitive to radiation, and has particularly high resolution and sensitivity, as well as a good pattern cross-sectional shape. The present invention relates to a photoresist composition for microfabrication. The positive photoresist according to the present invention is applied to a thickness of 0.5 to 3 μm onto a semiconductor wafer or a substrate made of glass, ceramics, metal, etc. by spin coating or roller coating. Thereafter, it is heated and dried, and a circuit pattern and the like are printed by UV irradiation through an exposure mask and developed to form a positive image. Further, by etching this positive image as a mask, it is possible to process a pattern on the substrate. Typical fields of application are the manufacturing process of semiconductors such as ICs, the manufacturing of circuit boards such as liquid crystals and thermal heads, and other photoabsorption processes. [0002] As a positive photoresist composition,
Generally, a composition containing an alkali-soluble resin and a naphthoquinone diazide compound as a photosensitive material is used. For example, USP-3,666,473 as "Novolak type phenolic resin/naphthoquinone diazide substituted compound"
No., USP-4,115,128 and USP-4,1
No. 73,470, etc., and as the most typical composition “
An example of "novolac resin consisting of cresol-formaldehyde/trihydroxybenzophenone-1,2 naphthoquinone diazide sulfonic acid ester" is given by Thompson "
"Introduction to Microlithography" (L.F. Thompson "Introduct")
ion to Microlithography
) (ACS Publishing, No. 219, P112-121
)It is described in. Novolak resin as a binder can be dissolved in alkaline aqueous solution without swelling,
It is also particularly useful in this application because it provides high resistance to plasma etching, especially when the generated image is used as an etching mask. In addition, the naphthoquinonediazide compound used in photosensitive materials itself acts as a dissolution inhibitor that reduces the alkali solubility of novolak resin, but when it decomposes upon exposure to light, it produces alkali-soluble substances and rather reduces the alkali solubility of novolak resin. It is unique in that it acts as a light enhancer, and because of its large change in properties with respect to light, it is particularly useful as a photosensitive material for positive photoresists. From this point of view, many positive photoresists containing novolac resins and naphthoquinone diazide photosensitive materials have been developed and put into practical use.
Sufficient results have been achieved in line width processing up to about 2 μm. However, the degree of integration of integrated circuits is increasing more and more, and in the production of semiconductor substrates such as VLSIs, 1
It has become necessary to process ultra-fine patterns having line widths of μm or less. In such applications, a photoresist is particularly required that has high resolution, high pattern shape reproduction accuracy to accurately copy the shape of the exposure mask, and high sensitivity from the viewpoint of high productivity. Additionally, in order to increase the degree of integration of integrated circuits, the etching method has shifted from conventional wet etching to dry etching, but since the temperature of the resist increases during dry etching, care must be taken to prevent thermal deformation. , resists are required to have high heat resistance. In order to improve heat resistance, a technique using a resin that does not contain components with a weight average molecular weight of 2000 or less (Japanese Patent Laid-Open No. 60-97347), a technique using a resin whose total content from monomer to trimer is 10% by weight or less (Japanese Patent Laid-Open No. 60-97347), 189739 (1989) has been published. However, when the above-mentioned resins in which low molecular weight components are removed or reduced are used, there are problems in that the sensitivity usually decreases and the throughput in device manufacturing decreases. Attempts have also been made to improve the sensitivity and developability of resists by incorporating specific compounds into resist compositions. For example, JP-A-61-141441 discloses a positive photoresist composition containing trihydroxybenzophenone. Although the sensitivity and developability of positive photoresists containing trihydroxybenzophenone are improved, there is a problem in that the addition of trihydroxybenzophenone deteriorates heat resistance. JP-A-64-44439, JP-A-1-177032
, No. 1-280748 and No. 1-10350 disclose a technique for increasing sensitivity without deteriorating heat resistance by adding an aromatic polyhydroxy compound other than trihydroxybenzophenone, but the developability It cannot be said that the improvement is necessarily sufficient. SUMMARY OF THE INVENTION An object of the present invention is to obtain a resist pattern with high sensitivity, excellent resolution, developability, resist shape, and heat resistance, which is particularly useful in the manufacture of semiconductor devices, etc. An object of the present invention is to provide a positive photoresist composition. [Means for Solving the Problems] The present inventors have kept in mind the above-mentioned characteristics and, as a result of extensive studies, have found that in a positive photoresist composition containing a quinonediazide compound and an alkali-soluble novolak resin, By controlling the dimer content and trimer content contained in the alkali-soluble novolak resin to be within a specific range in terms of area ratio of gel permeation chromatography (GPC) pattern, development defects can be eliminated and high resolution can be achieved. The inventors have found that the present invention is useful for obtaining the desired results, and have accomplished the present invention. That is, the object of the present invention is to provide a photoresist composition containing a quinonediazide compound and an alkali-soluble novolak resin, in which the amount of dimer (A) contained in the alkali-soluble novolak resin is equal to or less than the area of the gel permeation chromatographic pattern. 2 of the total novolak resin in ratio
6%, the amount of trimer (B) is 10 to 20%, and the ratio of trimer to dimer (B/A) is 2.0 to 10.
This was achieved using a positive photoresist composition characterized in that the The present invention will be explained in detail below. [0007] In the present invention, dimer refers to a dimer component of a novolak resin obtained by addition-condensing a predetermined phenol with an aldehyde in the presence of an acidic catalyst, and/or a dimer component represented by the following general formula (I). means the compound represented. ##STR1## Here, R1, R2: may be the same or different, hydrogen atom, halogen atom, alkyl group or alkoxy group, R3, R4: may be the same or different, hydrogen atom or Alkyl group, a, b, c, d: each is an integer of 1 to 3, and represents a+c=b+d=5. In R1 and R2 of general formula (I), the halogen atom is a chlorine atom, a bromine atom, or an iodine atom, and the alkyl group is a methyl group, an ethyl group, a propyl group, an n-butyl group, an isobutyl group, or a sec. - An alkyl group having 1 to 4 carbon atoms such as butyl group or t-butyl group, and alkoxy groups include methoxy group, ethoxy group, hydroxyethoxy group, propoxy group, hydroxypropoxy group, isopropoxy group, n-butoxy group - An alkoxy group having 1 to 4 carbon atoms such as isobutoxy group, sec-butoxy group or t-butoxy group is preferable. General formula (
In R3 and R4 in I), the alkyl group is an alkyl group having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group, n-butyl group, isobutyl group, sec-butyl group or t-butyl group. preferable. Specific examples of the compound represented by the general formula (I) include 2,2'-methylenebis(4-methylphenol), 2,2'-methylenebis(4-methoxyphenol), methylenebis(3-methyl phenol), methylenebis(2-methylphenol), 4,4'-ethylidenebisphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,4'-ethylidenebisphenol, 4,4'-methylenebis( 2,6-dimethylphenol), 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(3,4-dimethylphenol), 4,4'-(1-methylethylidene)bis(2
, 6-dimethylphenol), 2,2'-methylenebis(4-tert-butylphenol), 4,4'-methylenebis(2-tert-butyl-6-methylphenol), and the like. In the present invention, the term "trimer" refers to a trimer component of a novolak resin obtained by addition-condensing a specified phenol with an aldehyde in the presence of an acidic catalyst and/or a trimer component represented by the following general formula (II). (different from the trimer component of the novolak resin). ##STR2## Here, R5, R6, R7: may be the same or different, hydrogen atom, halogen atom, alkyl group or alkoxy group, R8, R9, R10, R11
: may be the same or different, hydrogen atom or alkyl group, l, m, n, p, q, r: each an integer of 1 to 3, l+p=n+r=5m+q=4. The halogen atom, alkyl group, and alkoxy group in R5 to R11 of general formula (II) are preferably the same as the specific examples in general formula (I). Specific examples of the compound represented by general formula (II) are listed below. [Chemical 3] [Chemical 4] [Chemical 4] [Chemical 5] [Chemical 6] [Chemical 6] [0019] The alkali-soluble novolak resin used in the present invention contains a predetermined monomer as a main component, It is obtained by condensation with aldehydes in the presence of an acidic catalyst. Examples of the predetermined monomers include cresols such as phenol, m-cresol, p-cresol, and o-cresol, 2,5-xylenol, 3,5-xylenol, and
Xylenol such as 3,4-xylenol and 2,3-xylenol, alkylphenols such as o-ethylphenol, m-ethylphenol, p-ethylphenol and pt-butylphenol, p-methoxyphenol and m- Methoxyphenol, 3,5-dimethoxyphenol, 2-methoxy-4-methylphenol, m-ethoxyphenol, p-ethoxyphenol, m-propoxyphenol, p-propoxyphenol, m-butoxyphenol, p-butoxyphenol, etc. Alkoxyphenols, bisalkylphenols such as 2-methyl-4-isopropylphenol, o-chlorophenol, m-chlorophenol, p-chlorophenol,
Hydroxy aromatic compounds such as dihydroxybiphenyl, bisphenol A, phenylphenol, resorcinol, and naphthol can be used alone or in combination of two or more, but are not limited to these. Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylaldehyde,
α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-
Hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde,
p-Nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-ethylbenzaldehyde, p-n-butylbenzaldehyde, furfural, chloroacetaldehyde, and acetals thereof, such as chloroacetaldehyde diethyl acetal, can be used. Of these, formaldehyde is preferred. These aldehydes may be used alone or in combination of two or more. As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, etc. can be used. The weight average molecular weight of the novolac resin thus obtained is preferably in the range of 2,000 to 30,000. When it is less than 2,000, film loss in unexposed areas after development is large, and when it exceeds 30,000, the development speed becomes low. Particularly preferred is a range of 6,000 to 20,000. Here, the weight average molecular weight is defined by the polystyrene equivalent value determined by gel permeation chromatography. As a method for adjusting the dimer component, for example, after synthesizing a novolac resin according to a conventional method, methanol, ethanol, acetone, methyl ethyl ketone,
There is a method in which the resin is dissolved in a polar solvent such as dioxane or tetrahydrofuran, and then poured into water or a water-polar solvent mixture to precipitate the resin component. As another method, when synthesizing an alkali-soluble resin, after a predetermined period of reaction, usually 150 to 2
Water, unreacted monomers, formaldehyde, and oxalic acid are removed by distillation under reduced pressure at 00°C, whereas at 230°C
The dimer component can be efficiently distilled off by distilling under reduced pressure, preferably at 250° C. or higher and 10 mmHg or lower. Furthermore, the method disclosed in Japanese Patent Application Laid-Open No. 2-60915 may be used. The dimer content of the novolak resin used in the present invention is in the range of 2 to 6% (GPC area ratio) of the entire resin, and the dimer component of the novolak resin can be adjusted by the above-mentioned operation. Alternatively, a dimer represented by the general formula (I) may be added to adjust the total dimer amount to 2 to 6% by weight. The trimer content of the novolac resin used in the present invention is in the range of 10 to 20% by weight (GPC area ratio) based on the total resin, and can be adjusted by the same method as the above-mentioned vacuum distillation. Furthermore, after performing the distillation operation under reduced pressure, a trimer represented by general formula (II) may be added to adjust the total trimer amount to be in the range of 10 to 20% by weight. By the above operations, trimmer (B) and dimer (
Adjust so that the ratio of A) (B/A) is in the range of 2.0 to 10.0. As disclosed in JP-A-1-276131, a small content of dimer is preferable in order to eliminate development defects and improve resolution, but if it is reduced to less than 2% by weight, the solubility in an alkaline aqueous solution deteriorates. Not only does the sensitivity decrease, but also the resolution, which is one of the main objectives of the present invention, decreases. Furthermore, there is a disadvantage that the adhesion with the silicon substrate deteriorates, which is not preferable. On the other hand, if the dimer content exceeds 6% by weight, it is not preferable because development defects tend to occur and heat resistance also decreases. Further, the dimer content is in the range of 2 to 6% by weight, but when the trimer content is less than 10% by weight, the resolution, heat resistance, and developability are quite good, but the resist shape is hardly improved. On the other hand, the dimer content is in the range of 2 to 6% by weight, but if the trimer content exceeds 20% by weight, the resist shape is good but poor development is likely to occur and storage stability is problematic. That is, the dimer content is in the range of 2 to 6% by weight, the trimer content is in the range of 10 to 20% by weight, and the ratio of trimer (B) to dimer (A) (B/
It was found that resolution, sensitivity, heat resistance, developability, and resist shape were extremely excellent only when A) was in the range of 2.0 to 10.0. It is not clear why the ratio of dimer content and trimer content is related to the resolution, developability, and resist shape of photoresists, but even if other low molecular components of novolak resin, that is, residual monomers, are adjusted, such effects cannot be obtained. Since this is not observed, it is presumed that this is a unique effect that occurs only when the dimer and trimer are present in the ratio within the above-mentioned specific range. The photosensitive material used in the present invention uses an esterified product of the following polyhydroxy compound with 1,2-naphthoquinonediazide-5-sulfonyl chloride and/or 1,2-naphthoquinonediazide-4-sulfonyl chloride. be able to. Examples of the polyhydroxy compound include 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2
, 4,6-trihydroxybenzophenone, 2,3,4
-trihydroxy-2'-methylbenzophenone, 2,
3,4,4'-tetrahydroxybenzophenone, 2,
2',4,4'-tetrahydroxybenzophenone, 2
, 4,6,3',4'-pentahydroxybenzophenone, 2,3,4,2',4'-pentahydroxybenzophenone, 2,3,4,2',5'-pentahydroxybenzo Phenone, 2,4,6,3',4',5'-hexahydroxybenzophenone, 2,3,4,3',4'
, 5'-hexahydroxybenzophenone and other polyhydroxybenzophenones, 2,3,4-trihydroxyacetophenone, 2,3,4-trihydroxyphenylpentyl ketone, 2,3,4-trihydroxybenzophenone, Polyhydroxyphenyl alkyl ketones such as hydroxyphenylhexyl ketone, bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, bis(2,4-dihydroxy Bis(phenyl)propane-1, bis(2,3,4-trihydroxyphenyl)propane-1, nordihydroguaiaretic acid, etc.
(Poly)hydroxyphenyl)alkanes, 3,4,5
- Polyhydroxybenzoic acid esters such as propyl trihydroxybenzoate, phenyl 2,3,4-trihydroxybenzoate, phenyl 3,4,5-trihydroxybenzoate, bis(2,3,4-trihydroxybenzoyl) ) methane, bis(3-acetyl-4,5,6-trihydroxyphenyl)methane, bis(2,3,4-trihydroxybenzoyl)benzene, bis(2,4,6-trihydroxybenzoyl)benzene, etc. bis(polyhydroxybenzoyl)alkanes or bis(polyhydroxybenzoyl)aryls, ethylene glycol-di(3,
5-dihydroxybenzoate), alkylene di(polyhydroxybenzoate) such as ethylene glycol di(3,4,5-trihydroxybenzoate), 2
, 3,4-biphenyltriol, 3,4,5-biphenyltriol, 3,5,3',5'-biphenyltetrol, 2,4,2',4'-biphenyltetrol,
2,4,6,3',5'-biphenylpentol, 2,
4,6,2',4',6'-biphenylhexol, 2
, 3,4,2',3',4'-biphenylhexol and other polyhydroxybiphenyls, 4,4'-thiobis(
Bis(polyhydroxy) sulfides such as 1,3-dihydroxy)benzene, bis(polyhydroxyphenyl) ethers such as 2,2',4,4'-tetrahydroxydiphenyl ether, 2,2',4 , bis(polyhydroxyphenyl) sulfoxides such as 4'-tetrahydroxydiphenyl sulfoxide, 2,2',4,4'
-Bis(polyhydroxyphenyl)sulfones such as diphenylsulfone, 4,4',3'',4''-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 4 ,4',2'',3'',4''-
Pentahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 2,3,4,2',3',4'-
Hexahydroxy-5,5'-diacetyltriphenylmethane, 2,3,4,2',3',4',3'',4'
Polyhydroxytriphenylmethane such as '-octahydroxy-5,5'-diacetyltriphenylmethane, 2,4,6,2',4',6'-hexahydroxy-5,5'-dipropionyltriphenylmethane Class, 3, 3,
3',3'-tetramethyl-1,1'-spirobi-indan-5,6,5',6'-tetrol, 3,3,3'
,3'-tetramethyl-1,1'-spirobi-indan-5,6,7,5',6',7'-hexol, 3,
3,3',3'-tetramethyl-1,1'-spirobiindane-4,5,6,4',5',6'-hexol, 3,3,3',3'-tetramethyl-1, Polyhydroxyspirobi-indanes such as 1'-spirobi-indane-4,5,6,5',6',7'-hexol, 3
, 3-bis(3,4-dihydroxyphenyl)phthalide, 3,3-bis(2,3,4-trihydroxyphenyl)phthalide, 3',4',5',6'-tetrahydroxyspiro[ polyhydroxyphthalides such as phthalide-3,9'-xanthene], 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxybenzopyran,
2-(3,4,5-trihydroxyphenyl)-3,5
, 7-trihydroxybenzopyran, 2-(3,4-dihydroxyphenyl)-3-(3,4,5-trihydroxybenzoyloxy)-5,7-dihydroxybenzopyran, 2-(3,4, 5-trihydroxyphenyl)
Polyhydroxybenzopyrans such as -3-(3,4,5-trihydroxybenzoyloxy)-5,7-dihydroxybenzopyran, flavonoid pigments such as morin, quercetin, rutin, etc. can be used. or,
Low-nuclear forms of phenolic resins such as novolac resins can also be used. These naphthoquinone diazide ester photosensitive materials of polyhydroxy compounds may be used alone or in combination of two or more. The ratio of photosensitive material and alkali-soluble resin used is 5 to 10 parts by weight of photosensitive material to 100 parts by weight of resin.
0 parts by weight, preferably 10 to 50 parts by weight. If the usage ratio is less than 5 parts by weight, the residual film rate will drop significantly, while if it exceeds 100 parts by weight, sensitivity and solubility in solvents will drop. The composition of the present invention may further contain a polyhydroxy compound to promote dissolution in a developer. Preferred polyhydroxy compounds include phenols, resorcinol, phloroglucin, 2,3,4-
Trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,3',4
',5'-hexahydroxybenzophenone, acetone-pyrogallol condensation resin, phlorogluside, 2,4,2
',4'-biphenyltetrol, 4,4'-thiobis(1,3-dihydroxy)benzene, 2,2',4,4
'-tetrahydroxydiphenyl ether, 2,2',
Examples include 4,4'-tetrahydroxydiphenyl sulfoxide and 2,2',4,4'-diphenyl sulfone. These polyhydroxy compounds can be blended in an amount of 50 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of the dimer and trimer of the present invention. Examples of the solvent for dissolving the photosensitive material and alkali-soluble novolak resin of the present invention include ketones such as methyl ethyl ketone and cyclohexanone, and 4-ethoxy-2
- Keto ethers such as butanone and 4-methoxy-4-methyl-2-pentanno, alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ethers such as dioxane and ethylene glycol dimethyl ether, methyl cellosolve acetate, ethyl Cellosolve esters such as cellosolve acetate, fatty acid esters such as butyl acetate, methyl lactate, ethyl lactate, halogenated hydrocarbons such as 1,1,2-trichloroethylene, dimethylacetamide,
Examples include highly polar solvents such as N-methylpyrrolidone, dimethylformamide, and dimethylsulfoxide. These solvents can be used alone or in combination. A surfactant may be added to the positive photoresist composition of the present invention in order to further improve the coating properties such as striation. Examples of surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene octyl phenol ether, and polyoxyethylene nonyl. Polyoxyethylene alkyl allyl ethers such as phenol ether, polyoxyethylene/polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristear Sorbitan fatty acid esters such as esters, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, etc. Nonionic surfactants such as ethylene sorbitan fatty acid esters, EFTOP EF3
01, EF303, EF352 (manufactured by Shin Akita Kasei Co., Ltd.)
, Megafuck F171, F173 (manufactured by Dainippon Ink Co., Ltd.), Florado FC430, FC431 (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103,
Fluorine-based surfactants such as SC104, SC105, and SC106 (manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), and acrylic or methacrylic acid (co)polymerized polyflow No. 7
5, No. 95 (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.). The blending amount of these surfactants is usually 2 parts by weight or less, preferably 1 part by weight or less, per 100 parts by weight of the alkali-soluble resin and quinonediazide compound in the composition of the present invention. These surfactants may be added alone or in some combination. The positive photoresist composition of the present invention may contain dyes, plasticizers, adhesion aids, etc., if necessary. Specific examples include dyes such as methyl violet, crystal violet, and malachite green, stearic acid, acetal resin, phenoxy resin,
Plasticizers such as alkyd resins, hexamethyldisilazane,
There are adhesion aids such as chloromethylsilane. The above-mentioned positive photoresist composition is applied onto a substrate (e.g. silicon/silicon dioxide coated) used in the manufacture of precision integrated circuit elements using an appropriate coating method such as a spinner or coater, and then passed through a prescribed mask. A good resist image can be obtained by exposing and developing. The developing solution for the positive photoresist composition of the present invention includes inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine,
Primary amines such as n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetra Aqueous solutions of alkalis such as quaternary ammonium salts such as methyl ammonium hydroxide and tetraethylammonium hydroxide, and cyclic amines such as pyrrole and piperidine can be used. Furthermore, appropriate amounts of alcohols and surfactants may be added to the aqueous alkali solution. [Examples] The present invention will be explained in more detail based on Examples below, but the present invention is not limited thereto. Note that % indicates weight % unless otherwise specified. Also,
The weight average molecular weight and content of monomer, dimer or trimer were measured using gel permeation chromatography (GPC) at 40°C, flow rate 1ml/min, TH
Measurement was performed using F solvent and a detection wavelength of 282 nm. The column used was Toyo Soda Kogyo TSKgel GMLXL, G400.
One each of 0HXL, G3000HXL, and G2000HXL was connected, and the weight average molecular weight was calculated using monodisperse polystyrene as a standard. The contents of monomer, dimer, and trimer were also measured and calculated under the same conditions. [Synthesis and/or adjustment of novolak resin]
Synthesis Example 1 Synthesis of novolak resin a 45 g of m-cresol, 55 g of p-cresol, 37%
53 g of formalin aqueous solution and 0.1 g of oxalic acid were placed in a three-necked flask, and the temperature was raised to 100°C while stirring.
The reaction was allowed to proceed for 15 hours. Then raise the temperature to 200℃,
The pressure was gradually reduced to 5 mmHg to distill off water, unreacted monomers, formaldehyde, oxalic acid, and the like. The molten alkali-soluble novolak resin was then returned to room temperature and recovered. The obtained novolac resin (a) had an average molecular weight of 83
00 (polystyrene equivalent), and the monomer, dimer, and trimer contents are 0.5%, 12.7%, and 7.1, respectively.
% (total 20.3%). Preparation Example 1 Preparation of Novolak Resin b After dissolving 20 g of the novolak resin (a) obtained in Synthesis Example 1 in 60 g of methanol, 30 g of water was gradually added to the solution while stirring to remove the resin. precipitated. The upper layer was removed by decantation and the precipitated resin was collected.
The mixture was heated to 0° C. and dried under reduced pressure for 24 hours to obtain alkali-soluble novolak resin b. The obtained novolak resin has a weight average molecular weight of 9110 (polystyrene equivalent), and the monomer, dimer, and trimer contents are 0% and 4%, respectively.
．． 7% and 6.3% (total 11.0%). Preparation Examples 2 to 4 Preparation of Novolak Resins c to e The trimers shown in Table 1 were added to the novolak resin (b) obtained in Preparation Example 1, and the trimer components of the novolak resin were adjusted. Resins c to e were obtained. Table 1 shows the adjusted monomer, dimer, and trimer contents. Adjustment Example 5 Adjustment of novolac resin f m-
38 g of cresol, 62 g of p-cresol, 47 g of a 37% formalin aqueous solution, and 0.1 g of oxalic acid were placed in a three-necked flask, and the temperature was raised to 100°C while stirring.
Allowed time to react. After that, the temperature was raised to 250°C, and the pressure was gradually reduced to 1 mmHg to remove water, unreacted monomer,
Formaldehyde, oxalic acid, dimer components, etc. were distilled off. Then, the molten alkali-soluble novolak resin was returned to room temperature and recovered. The obtained novolac resin had an average molecular weight of 7,200 (in terms of polystyrene). A trimer shown in Table 1 was further added to the novolak resin obtained here to adjust the trimer component to obtain a novolak resin f. After adjustment, the monomer, dimer, and trimer contents determined by GPC were 0%, 4.1%, and 18.6%, respectively (total of 2%).
2.7%). Adjustment Example 6 Adjustment of novolak resin g m-
25 g of cresol, 50 g of p-cresol, 28 g of 3,5-xylenol, 53 g of a 37% aqueous formalin solution, and 0.1 g of oxalic acid were placed in a three-necked flask, heated to 100° C. with stirring, and reacted for 15 hours. Thereafter, the temperature was raised to 250° C., and the pressure was gradually reduced to 1 mmHg to distill off water, unreacted monomers, formaldehyde, oxalic acid, dimer components, and the like. Then, the molten alkali-soluble novolak resin was returned to room temperature and recovered. The obtained novolak resin had an average molecular weight of 4,700 (in terms of polystyrene). The trimer shown in Table 1 was further added to the novolak resin obtained here to adjust the trimer component to obtain novolak resin g. After adjustment, the monomer, dimer, and trimer contents determined by GPC were each 0.
5%, 4.8%, and 17.3% (total 22.6%). Preparation Example 7 Preparation of Novolak Resin h To the novolak resin (a) obtained in Synthesis Example 1, the trimer shown in Table 1 was added to adjust the trimer component to obtain Novolak Resin h. Monomer determined by GPC after adjustment,
The content of dimer and trimer is 0.5% and 11.9%, respectively.
, 13.6% (total 26.0%). Synthesis Example 2 Synthesis of Photosensitive Material A 2,3,4-
11.5 g of trihydroxybenzophenone, 30.2 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride
Pour g and 300 ml of acetone into a three-necked flask,
Dissolved uniformly. Then triethylamine/acetone=
Gradually drop a mixture of 11.4g/50ml and heat to 25°C.
The mixture was allowed to react for 3 hours. The reaction mixture was diluted with 1% aqueous hydrochloric acid solution.
The precipitate formed was filtered, washed with water and dried (40°C), and 1,2-naphthoquinonediazide-5-sulfonic acid ester of 2,3,4-trihydroxybenzophenone (photosensitive 29.8 g of product A) was obtained. Synthesis Example 3 Synthesis of Photosensitive Material B 2, 3, 4,
4'-tetrahydroxybenzophenone 12.3g, 1
, 40.3 g of 2-naphthoquinonediazide-5-sulfonyl chloride and 300 ml of acetone were charged into a three-necked flask and uniformly dissolved. Next, a mixture of triethylamine/acetone (15.2 g/50 ml) was gradually added dropwise, and the mixture was reacted at 25° C. for 3 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, the resulting precipitate was filtered, washed with water and dried (40°C), and 1,2 of 2,3,4,4'-tetrahydroxybenzophenone was removed. -Naphthoquinone diazide-5-sulfonic acid ester (photosensitive material B) 39.7 g
I got it.
[Preparation and evaluation of positive photoresist compositions] The novolak resins a to h obtained in Synthesis Example 1 and Preparation Examples 1 to 7 above, and the photosensitive materials A and B obtained in Synthesis Examples 2 and 3, were A photoresist composition was prepared by dissolving the solution in 15 g of ethyl cellosolve acetate in the proportions shown in Table 2 and filtering it using a 0.2 μm microfilter. This photoresist composition was applied onto a silicon wafer using a spinner, and then heated at 90°C in a convection oven under a nitrogen atmosphere.
, and dried for 30 minutes to obtain a resist film with a thickness of 1.2 μm. This film was coated with a reduction projection exposure device FPA-15 manufactured by Canon Inc.
50 through a test chart mask, developed with a 2.38% aqueous solution of tetramethylammonium hydroxide for 1 minute, washed with water for 30 seconds, and dried. The resist pattern thus obtained on the silicone wafer was observed with a scanning electron microscope, and the resist was evaluated. The results are shown in Table 3. Sensitivity was defined as the reciprocal of the exposure amount for reproducing a 0.70 μm mask pattern, and was expressed as a relative value to the sensitivity of Comparative Example 1. The residual film rate was expressed as a percentage of the ratio of the unexposed area before and after development. The resolution represents the limit resolution at an exposure dose that reproduces a 0.70 μm mask pattern. The shape of the resist is determined by the angle (
θ). Developability was determined by observing surface layer peeling and film residue.
◯ indicates that these are not observed and is good, △ indicates that a few are observed, and × indicates that a lot of these are observed. Heat resistance is
The resist-patterned silicon wafer was baked in a convection oven for 30 minutes to reach a temperature at which no deformation of the pattern occurred. As can be seen from Table 3, the resist using the novolac resin of the present invention has a high sensitivity, residual film rate,
The resolution, heat resistance, resist shape, and developability were all excellent. [Table 1] [Table 2] [Table 2] [Table 3] [Table 4] [Table 5] [Table 5] [Effects of the Invention] Positive photoresist of the present invention is the sensitivity,
It has excellent residual film rate, resolution, heat resistance, resist shape, and developability, and is suitably used as a photoresist for microfabrication.

Claims (1)

[Claims] 1. In a photoresist composition containing a quinone diazide compound and an alkali-soluble novolak resin, the amount of dimer (A) contained in the alkali-soluble novolak resin is such that the amount of dimer (A) is equal to or less than the novolak in the area ratio of the gel permeation chromatographic pattern. 2-6% of the total resin
, a positive photoresist composition characterized in that the amount of trimer (B) is 10 to 20%, and the ratio of trimer to dimer (B/A) is 2.0 to 10.0.