JPH0656488B2 - Positive photosensitive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. TECHNICAL FIELD The present invention relates to a positive photosensitive resin composition.

b. 2. Description of the Related Art Conventionally, as a photoresist for producing an integrated circuit, a negative photoresist in which cyclized isoprene rubber is mixed with a bisazide compound is known. However, this negative photoresist has a limitation in resolution, and therefore has a drawback that it cannot sufficiently cope with high integration of integrated circuits. On the other hand, compared with the negative photoresist, the positive photoresist is expected to be sufficiently compatible with high integration of integrated circuits because of its excellent resolution.

Almost all of the positive photoresists currently used for integrated circuit fabrication are alkali-soluble novolac resins.
A 1,2-quinonediazide compound was added to make it difficult to dissolve in an alkaline aqueous solution as a developing solution. This novolac resin-based positive photoresist has a lower sensitivity than the cyclized rubber-based negative photoresist because it requires a large amount of 1,2-quinonediazide compound.

c. Problems to be Solved by the Invention When the addition amount of a 1,2-quinonediazide compound is lowered in order to improve the sensitivity of a novolac resin-based positive photoresist, the solubility in an alkaline aqueous solution of a resist coating film before exposure is somewhat increased, and a photomask is formed. It seems that the developability after exposure is improved and the sensitivity is increased. However, the unexposed portion to be left as a resist pattern is dissolved to some extent because the addition amount of the 1,2-quinonediazide compound is small, though not so much as the exposed portion, and the height of the pattern is reduced. The ratio of the height of the unexposed portion to be left as a resist pattern before the exposure and after the development is called the residual film rate, and the conventional novolac resin-based positive photoresist has a low residual film rate. If a resist pattern is formed by applying a novolac resin-based positive photoresist with a low residual film ratio to a substrate having a step structure, exposing it, and developing it, the step part cannot be sufficiently covered with the resist pattern, so that a normal integrated circuit Is difficult to manufacture.

In addition, when a wet etching method using hydrofluoric acid, nitric acid, phosphoric acid, or the like as an etchant is used as an etching step after formation of a resist pattern in integrated circuit manufacturing, it is difficult to etch only the vertical direction of the substrate, and side etching or Since under-etching cannot be avoided at the same time, the resolution cannot be increased. In order to solve this drawback in a process manner, it is preferable to adopt a dry etching method in which halogenated hydrocarbon or the like is converted into plasma and used as an etchant. However, according to this method, reactive ions such as fluorine ions and chlorine ions attack the resist pattern as well. Therefore, if the dry etching resistance is poor, the temperature of the substrate rises, and The damage is large, the processing accuracy of the substrate is deteriorated, and the yield of the integrated circuit is deteriorated. It is said that the novolak resin-based positive photoresist has better dry etching resistance than other resists, but the conventional novolac resin-based positive photoresist has not reached a sufficiently satisfactory level.

Under such circumstances, an object of the present invention is to provide a positive photosensitive resin composition having high sensitivity, high residual film rate, high dry etching resistance, heat resistance, and developability. Is.

d. Means for Solving the Problems The gist of the present invention is to provide an alkali-soluble novolac resin and 1,
In a positive photosensitive resin composition comprising a 2-quinonediazide compound, the alkali-soluble novolac resin is
m-cresol 30 to 90 (molar ratio), p-cresol 5 to 40 (molar ratio), and general formula (I). (In the formula, R ₁ and R ₂ are the same or different, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, R ₃ and R ₄ are the same or different, and a hydrogen atom and the number of carbon atoms are 1 to 4; And an alkyl group R ₅ , R ₆ and R ₇ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, and n represents 0 or 1. The positive photosensitive resin composition is characterized in that it is a novolak resin obtained by condensing xylenol 5 to 70 (molar ratio) added according to the above with an aldehyde.

Here, examples of the compound (I) include o-phenylphenol, m-phenylphenol, p-phenylphenol, 3-methyl-4-phenylphenol and 2,4 ′.
-Dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylmethane, 2,4'-dihydroxydiphenylmethane, 2,2'-dihydroxydiphenylmethane, 2,2'-dihydroxy -3,3'-Dimethyldiphenylmethane, 2,2'-dihydroxy-5,5'-dimethyldiphenylmethane, 2,4,2'-trihydroxydiphenylmethane, 2,4'-dihydroxy-5-methyldiphenylmethane, 2,2 ′ -Dimethyl-4,4′-dihydroxydiphenylmethane, 3,3′-dimethyl-4,4′-dihydroxydiphenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 2- Ethyl-4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylpropane- (2,2), 2,4,2 ', 4'-tetrahydroxy Diphenylpropane- (2,2), 4,4'-dihydroxydiphenyl-n-butane- (2,2), 4,4'-dihydroxydiphenyl-n-pentane- (2,2), 2,3,4 , 2 ', 3', 4'-
Hexahydroxydiphenylpropane- (2,2), 3,3'-
Examples thereof include dimethyl-2,4,2 ', 4'-tetrahydroxydiphenylpropane- (2,2).

Further, as xylenol, 2,3-xylenol, 2,4
-Xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol and the like can be mentioned.

The alkali-soluble novolac resin has a monomer charge composition of m-cresol / p-cresol / the compound represented by the general formula (I) and xylenol of 30 to 90/5 to 40 /, in order to further exert the effects of the present invention. 5 to 70 (molar ratio), especially 50 to 90/5 to 40/5 to 50 (molar ratio),
It is a novolak resin that is condensed using aldehydes. In addition, the alkali-soluble novolak resin in the present invention contains a co-condensable monomer such as phenol or o.
-Cresol, ethylphenol, t-butylphenol, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, trihydroxybenzene and the like can be co-condensed to the extent that the effects of the present invention are not deviated.

The alkali-soluble novolak resin in the present invention is synthesized by condensing a predetermined monomer with an aldehyde in the presence of an acidic catalyst. Examples of aldehydes include formaldehyde, paraformaldehyde, furfural, acetaldehyde, benzaldehyde and the like, but formaldehyde is preferably used. As the acidic catalyst, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid,
An organic acid such as acid or acetic acid is used. The amount of the aldehyde used is 0.7 to 3 mol per 1 mol of the predetermined monomer, and the amount of the acidic catalyst used is 1 × 10 ^{−4 to} 5 × 10 ⁻³ mol per 1 mol of the predetermined monomer. It is common. The reaction temperature is usually 70 to 130 ° C.

The 1,2-quinonediazide compound used in the present invention is not particularly limited, for example, 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, Examples thereof include 1,2-naphthoquinonediazide-5-sulfonic acid ester, and specific examples thereof include p-cresol-1,2-benzoquinonediazide-4-sulfonic acid ester and resorcin-
1,2-naphthoquinonediazide-4-sulfonic acid ester, pyrogallol-1,2-naphthoquinonediazide-5-
Of (poly) hydroxybenzene such as sulfonate
1,2-quinonediazidesulfonic acid esters, 2,4-dihydroxyphenyl-propylketone-1,2-benzoquinonediazide-4-sulfonic acid ester, 2,4-dihydroxyphenyl-n-hexylketone-1,2-naphtho Quinonediazide-4-sulfonic acid ester, 2,4-dihydroxybenzophenone-1,2-naphthoquinonediazide-5
-Sulfonic acid ester, 2,3,4-trihydroxyphenyl-n-hexylketone-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide- 4-sulfonic acid ester, 2,3,4-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,4,6-trihydroxybenzophenone-1,2-naphthoquinonediazide-4-sulfonic acid Ester, 2,4,6
-Trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid ester and other (poly) hydroxyphenylalkylketones or (poly) hydroxyphenylarylketone 1,2-quinonediazidesulfonic acid esters, bis (p-hydroxy) Phenyl) methane-1,2-naphthoquinonediazide-4-sulfonic acid ester, bis (2,4-dihydroxyphenyl) methane-1,2
-Naphthoquinonediazide-5-sulfonic acid ester, bis (2,3,4-trihydroxyphenyl) methane-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,2-
Bis (p-hydroxyphenyl) propane-1,2-naphthoquinonediazide-4-sulfonic acid ester, 2,2-bis (2,4-dihydroxyphenyl) propane-1,2-naphthoquinonediazide-5-sulfonic acid ester, 2,2-bis (2,3,4-trihydroxyphenyl) propane-1,2-
1,2-quinonediazide sulfonic acid esters of bis [(poly) hydroxyphenyl] alkanes such as naphthoquinonediazide-5-sulfonic acid ester, 3,5-dihydroxybenzoic acid lauryl-1,2-naphthoquinonediazide-4
-Sulfonic acid ester, 2,3,4-trihydroxybenzoic acid phenyl-1,2-naphthoquinonediazide-5-sulfonic acid ester, 3,4,5-trihydroxybenzoic acid propyl-1,2-naphthoquinonediazide-5 -Sulfonic acid ester, phenyl 3,4,5-trihydroxybenzoate-1,2-
1,2- of (poly) hydroxybenzoic acid alkyl ester such as naphthoquinone diazide-5-sulfonic acid ester or (poly) hydroxybenzoic acid aryl ester
Quinone diazide sulfonates, bis (2,5-dihydroxybenzoyl) methane-1,2-naphthoquinone-
4-sulfonic acid ester, bis (2,3,4-trihydroxybenzoyl) methane-1,2-naphthoquinonediazide-
5-sulfonic acid ester, bis (2,4,6-trihydroxybenzoyl) methane-1,2-naphthoquinonediazide-
5-sulfonic acid ester, p-bis (2,5-dihydroxybenzoyl) benzene-1,2-naphthoquinonediazide-4-sulfonic acid ester, p-bis (2,3,4-trihydroxybenzoyl) benzene-1, 2-naphthoquinonediazide-5-sulfonic acid ester, p-bis (2,4,6-
Trihydroxybenzoyl) benzene-1,2-naphthoquinonediazide-5-sulfonic acid ester and other bis [(poly) hydroxybenzoyl] alkanes or bis [(poly) hydroxybenzoyl] benzene 1,2-quinonediazidesulfonic acid esters, Ethylene glycol-di (3,5-dihydroxybenzoate) -1,2-naphthoquinonediazide-4-sulfonic acid ester, polyethylene glycol-di (3,5-dihydroxybenzoate) -1,2
-Naphthoquinone diazide-5-sulfonic acid ester, polyethylene glycol-di (3,4,5-trihydroxybenzoate) -1,2-naphthoquinone diazide-5-sulfonic acid ester and the like (poly) ethylene glycol-di [(poly ) Hydroxybenzoate] 1,2-quinonediazide sulfonic acid esters. Besides these exemplified 1,2-quinonediazide compounds, J. Kosar
Written "Light-Sensitive Systems" 339-352, (1965), Joh
n Wiley & Sons (New York) and WS De Forest “Photor
Mention may also be made of the 1,2-quinonediazide compounds described in esist "50, (1975), McGraw-Hill, Inc., (New York).

The amount of the 1,2-quinonediazide compound used is 5 to 1 with respect to 100 parts by weight of the alkali-soluble novolac resin.
It is 00 parts by weight, preferably 10 to 50 parts by weight. If the amount is less than 5 parts by weight, the amount of carboxylic acid produced by the 1,2-quinonediazide compound by absorbing light is small, and patterning is difficult. If the amount is more than 100 parts by weight, 1,2- All of the quinonediazide compounds cannot be decomposed, making it difficult to develop with a developer containing an alkaline aqueous solution.

The positive photosensitive resin composition of the present invention is prepared by dissolving the alkali-soluble novolac resin and the 1,2-quinonediazide compound in a solvent, and examples of the solvent include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. Glycol ethers, methyl cellosolve acetate, cellosolve esters such as ethyl cellosolve acetate, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and cyclohexanone, and esters such as ethyl acetate and butyl acetate. it can. Further, two or more kinds of these solvents can be mixed and used. Further, ethers such as benzyl ethyl ether and dihexyl ether, glycol ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether, ketones such as acetonylacetone and isophorone, fatty acids such as caproic acid and caprylic acid, and 1-octanol. , 1-
It is also possible to add alcohols such as nonanol and benzyl alcohol, and high boiling point solvents such as benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, ethylene carbonate, propylene carbonate and esters such as phenyl cellosolve acetate. Further, if necessary, a surfactant, a storage stabilizer, a dye, a pigment and the like can be added to the positive photosensitive resin composition of the present invention.

Further, in order to improve the adhesive force between the coating film of the positive photosensitive resin composition of the present invention and a substrate such as a silicon oxide film, hexamethyldisilazane, chloromethylsilane, or the like may be applied to the substrate to be coated in advance. it can.

The developer of the positive photosensitive resin composition of the present invention includes sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, inorganic alkalis such as aqueous ammonia, ethylamine, n-propylamine and the like. Primary amines, secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide , Quaternary ammonium salts such as tetraethylammonium hydroxide or pyrrole, piperidine, 1,8-diazabicyclo
(5,4,0) -7-undecene, 1,5-diazabicyclo (4,3,
An aqueous solution of cyclic amines such as (0) -5-nonene is used,
It is preferable to use an aqueous solution of a quaternary ammonium salt or a cyclic amine when producing an integrated circuit in which the use of a metal-containing developer is a problem. In addition, methanol in the above aqueous solution,
An aqueous solution containing a water-soluble organic solvent such as alcohols such as ethanol or a surfactant added in an appropriate amount can also be used as the developer.

e. EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 In a three-neck separable flask having an internal volume of 500 ml, 77.8 g of m-cresol, 25.9 g of p-cresol and 2,2-bis (p
-Hydroxyphenyl) propane 54.7 g [m-cresol / p-cresol / 2,2-bis (p-hydroxyphenyl) propane = 60/20/20 (molar ratio)], and then 37% by weight Formaldehyde aqueous solution
92 ml and 0.04 g of acid were added. Next, the separable flask was immersed in an oil bath with stirring, the internal temperature was controlled at 100 ° C., and an addition condensation reaction was carried out for 6 hours. After the reaction, the temperature of the oil bath was raised to 180 ° C. and the pressure was simultaneously reduced to 20 mmHg to remove water and unreacted materials. Then, the molten novolak resin [hereinafter, abbreviated as "novolak resin A"] was returned to room temperature and recovered.

Novolak resin A (13 g) and 2,4,6-trihydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonic acid triester (2 g) were dissolved in ethyl cellosolve acetate (35 g) and then passed through a membrane filter having a pore size of 0.2 μm to give a positive type. A solution of the photosensitive resin composition was prepared.

The above solution was applied on a silicon wafer having a silicon oxide film by a spinner, and then prebaked at 90 ° C. for 30 minutes in an oven to form a resist film having a thickness of 1 μm. Optical As via the photo mask manufactured by Toppan Printing Co., Ltd.
Sciates, Inc. Model 205 UV irradiation with an energy (365 nm) calibrated by a UV intensity meter of 11.2 mJ / cm ² and irradiation with 20% tetramethylammonium hydroxide 2% by weight aqueous solution
When developed at 60 ° C. for 60 seconds, a pattern having a line width of 1.0 μm could be resolved. Further, the residual film rate of this resist was measured, and it was a very high value of 97%. Therefore, it was found that this positive photosensitive resin composition has high sensitivity and high residual film rate.

Next, the obtained resist pattern was mounted on a parallel plate type plasma dry etching system (electrode spacing 40 mm) and output 10
Carbon tetrafluoride / oxygen (95/5 volume ratio) was turned into plasma under the conditions of 0 W and a gas pressure of 15 Pa, and the dry etching resistance of the resist pattern was examined. The ratio of the silicon oxide film to the etching rate of the resist pattern is called the selection ratio. As a result of this example, the selection ratio shows a very high value of 3.3, and the novolak resin A has excellent dry etching resistance. Was confirmed.

Comparative Example 1 Monomer charge of Example 1 was changed to 113.4 g of m-cresol,
Example 1 except that 16.2 g of p-cresol [m-cresol / p-cresol = 87.5 / 12.5 (molar ratio)] was used.
A novolak resin was synthesized in the same manner as in.

Using this novolac resin, a solution of a positive photosensitive resin composition was prepared in the same manner as in Example 1, and a resist pattern was formed. The sensitivity was 15 mJ / cm ² , which was relatively good, but the residual film The rate was as low as 80%, and the balance between the sensitivity and the residual film rate was unbalanced. In addition, the selection ratio in the dry etching resistance test was as low as 2.2, and the dry etching resistance was poor.

Examples 2 to 4 A novolak resin was synthesized in the same manner as in Example 1 except that the monomer charge amount in Example 1 was changed to each monomer shown in Table 2. Using this novolak resin, a solution of a positive photosensitive resin composition was prepared in the same manner as in Example 1, and then a resist pattern was formed. The results are shown in Table-2. All of them were excellent in sensitivity, residual film rate and dry etching resistance.

Comparative Example 2 The amount of the monomer charged in Example 1 was changed to 65 g of p-cresol and 102 g of p-phenylphenol [p-cresol / p.
-Phenylphenol = 50/50 (molar ratio)] was used to synthesize a novolak resin in the same manner as in Example 1. Using this novolac resin, a solution of the positive photosensitive resin composition was prepared in the same manner as in Example 1, and then a resist pattern was formed. As a result, the pattern with a line width of 1.0 μm could not be resolved even when irradiated with 40 mJ / cm ² of ultraviolet light, and the sensitivity was low.

f. EFFECTS OF THE INVENTION The positive photosensitive resin composition of the present invention has high sensitivity, high residual film ratio, high dry etching resistance, and also excellent heat resistance and developability.

Generally, in a positive type photosensitive resin composition, the sensitivity and the residual film rate are in a trade-off relationship, and it is very difficult to improve both properties at the same time, but the positive type photosensitive resin composition of the present invention Shows that the sensitivity and the residual film rate are improved at the same time.

The positive photosensitive resin composition of the present invention is not only particularly useful as a positive photoresist for producing an integrated circuit,
It is also useful as a positive photoresist for mask making.

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Claims (1)

[Claims] 1. An alkali-soluble novolac resin and 1,2-
In the positive photosensitive resin composition comprising a quinonediazide compound, the alkali-soluble novolac resin is m-
Cresol 30 to 90 (molar ratio) and p-cresol 5
-40 (molar ratio) and the general formula (I) (In the formula, R ₁ and R ₂ are the same or different, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, R ₃ and R ₄ are the same or different, and a hydrogen atom and the number of carbon atoms are 1 to 4; And an alkyl group R ₅ , R ₆ and R ₇ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, and n represents 0 or 1. A positive photosensitive resin composition, which is a novolac resin obtained by condensing xylenol 5 to 70 (molar ratio) added according to the above with an aldehyde.