JPH05113662A - Production of photosensitive resin composition and resist image - Google Patents

Abstract

PURPOSE:To obtain a compsn. having excellent resolution, sensitivity and heat resistance and fit for a positive type resist for producing a high integrated circuit. CONSTITUTION:When a photosensitive resin compsn. contg. alkali-soluble novolak resin and a quinonediazido compd. is produced, the novolak resin is freed of a low mol.wt. component and a cyclic phenol compd. represented by the structural formula is further incorporated. A coating film of the resulting photosensitive resin compsn. is exposed and developed to produce a resist image. In the formula, R1 is H, alkyl or alkoxy, R2 is H, alkyl, alkoxy or phenyl, R1 and R2 may be the same and (n) is an integer of 4-8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition and a method for producing a resist image, and more specifically, a photosensitive resist which is a positive resist having high resolution, high sensitivity and high heat resistance for producing a highly integrated circuit. Resin composition and a method for producing a resist image using the same.

[0002]

2. Description of the Related Art Positive type resists are commonly used in semiconductor manufacturing processes. In recent years, with high integration of integrated circuits, a positive resist having high resolution, high sensitivity, high heat resistance, and high dry etching resistance is desired. Heretofore, attempts have been made to improve the alkali-soluble novolac resin used in a positive resist in order to increase the resolution of the positive resist. For example, as an alkali-soluble novolac resin, U.S. Pat. No. 4,529,682 describes
A novolac resin obtained by condensing a mixture of o-cresol, m-cresol and p-cresol with formaldehyde has been proposed. JP-A-60-1584
No. 40 discloses a novolak resin obtained by condensing a mixture of m-cresol, p-cresol and 2,5-xylenol with formaldehyde. JP-A-63-234249 proposes a novolac resin obtained by condensing a mixture of m-cresol, p-cresol and 3,5-xylenol with formaldehyde. Thus, high-resolution, high-sensitivity positive resist could be obtained by limiting the synthetic raw material of the alkali-soluble novolac resin.
It was not possible to obtain a product with high heat resistance.

In order to improve the heat resistance of positive resist,
Attempts have been made to improve alkali-soluble novolac resins. For example, JP-A 64-14229 and JP-A 2-60915 propose that the low molecular weight portion of the novolak resin is removed to improve the heat resistance. However, by removing the low molecular weight portion of the novolac resin, the resolution and sensitivity were lowered, and it was not possible to obtain a positive resist with well-balanced characteristics. JP-A-2-275955 proposes to add a specific polyphenol to compensate for the lowered resolution and sensitivity, but it has been difficult to balance the resolution, sensitivity and heat resistance.

[0004]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks of the prior art and provides a photosensitive resin composition which becomes a positive resist having high resolution, high sensitivity and high heat resistance, and a resist image using the same. The present invention provides a manufacturing method of.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies to achieve the above-mentioned object, and as a result, a photosensitive resin composition to be a positive resist having high resolution, high sensitivity and high heat resistance by the following means. I got things. That is, the present invention provides a photosensitive resin composition containing an alkali-soluble novolak resin and a quinonediazide compound, wherein the alkali-soluble novolac resin has a polystyrene reduced molecular weight of 2
000 or less low molecular weight components are removed in an amount of 30 to 100% by weight, and a photosensitive resin composition containing a phenolic cyclic compound represented by the following structural formula (I) and a resist image using the same Regarding manufacturing method.

[Chemical 2] (R ₁ represents hydrogen, an alkyl group or an alkoxy group, R ₂ represents hydrogen, an alkyl group, an alkoxy group or a phenyl group, and R ₁ and R ₂ may be the same,
n represents an integer of 4 to 8. )

In the present invention, the inclusion of the above-mentioned phenolic cyclic compound makes it possible to compensate for the decrease in resolution caused by the removal of the low molecular weight component of the alkali-soluble novolac resin and maintain the heat resistance. Phenolic cyclic compounds represented by the structural formula (I) include calixarene (Gutsche), topics in current chemistry (Topics in Curr).
ent Chemistry) 123, 1 (198)
4)), which is preferably contained in an amount of 3 to 40% by weight, more preferably 10 to 30% by weight, based on the alkali-soluble novolac resin and the phenolic cyclic compound. When the content of this compound is small, the effect of improving the resolution is small, and when the content is large, the solubility in the resist solution tends to be poor.

The phenolic cyclic compound represented by the structural formula (I) is a known compound, and can be obtained by polycondensing phenols having a phenolic hydroxyl group and aldehydes in the presence of a metal alkali catalyst. Examples of phenols having a phenolic hydroxyl group are phenols having a substituent at the para position, and examples thereof include p-cresol and p-tert-butylphenol.
Formaldehyde, paraformaldehyde, etc. are mentioned as aldehydes. The metal alkali catalyst has a so-called template effect that determines the size of the ring, and examples thereof include potassium hydroxide and sodium hydroxide. Such phenols, aldehydes and metal alkali catalysts can be added to diphenyl ether, ethylene glycol, etc.
It is refluxed for 3 to 20 hours in a solvent having a boiling point of 50 to 250 ° C., and polycondensation reaction is carried out while removing condensed water. The reaction product can be purified by washing with a solvent such as chloroform, acetone or hexane.

The alkali-soluble novolac resin used in the present invention is not particularly limited as long as it is a novolac resin which is soluble in an alkaline aqueous solution, but phenols having one or more phenolic hydroxyl groups are polycondensed with aldehydes. Novolak resins are preferred. Examples of phenols include phenol, o-cresol, m-
Cresol, p-cresol, 2,3-xylenol,
2,4-xylenol, 2,5-xylenol, 3,4
-Xylenol, 3,5-xylenol, 2,3,5-
Phenols containing one phenolic hydroxyl group such as trimethylphenol, phenols containing two phenolic hydroxyl groups such as resorcinol and catechol, and phenols containing three phenolic hydroxyl groups such as phloroglucin, pyrogallol and hydroxyhydroquinone. Can be mentioned. These phenols may be used alone or in combination of two or more. Examples of aldehydes include formaldehyde and paraformaldehyde. The amount of aldehydes used is preferably in the range of 0.5 to 1.5 mol per mol of phenols. As a catalyst for polycondensation, an acid catalyst capable of having a high molecular weight is preferable. Examples of the acid catalyst include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as formic acid, oxalic acid and acetic acid. The amount of the acid catalyst used is 1 × 10 ⁻⁵ to 1 mol of phenols.
A range of 1 × 10 ^-1 mol is preferred. The reaction temperature for polycondensation can be appropriately adjusted depending on the reactivity of the synthetic raw materials, but is usually 70 to 130 ° C. Examples of the polycondensation method include a method in which phenols, aldehydes and an acid catalyst are collectively charged, and a method in which phenols and aldehydes are added in the presence of an acid catalyst as the reaction proceeds. After completion of polycondensation, in order to remove unreacted raw materials, condensation water, acid catalyst, etc. existing in the reaction system,
The temperature in the reaction system is raised to 150 to 200 ° C. under reduced pressure, for example, 20 to 50 mmHg, and then the resin is recovered.

In the present invention, the low molecular weight component of the alkali-soluble novolak resin thus obtained is reduced or removed before use. The dissolution fractionation method is generally used as a method for reducing or removing low-molecular weight components. That is,
Dissolve the alkali-soluble novolac resin in a good solvent to make a varnish, and add this varnish to a poor solvent to divide it into a dilute phase with many low-molecular weight components and a concentrated phase with many high-molecular weight components, or a high-molecular weight component. By creating a precipitation phase, low molecular weight components are reduced or eliminated. Also,
As described in JP-A 64-14229, the alkali-soluble novolac resin may be crushed and dispersed in an aromatic solvent for extraction to reduce or remove low molecular weight components. By such a method, the polystyrene-converted molecular weight of the alkali-soluble novolac resin is 2,000.
Low molecular weight components of 0 or less can be removed in the range of 30 to 100% by weight.

Examples of the quinonediazide compound used in the photosensitive resin composition of the present invention include 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2
-Naphthoquinonediazide-5-sulfonic acid ester and the like. The blending amount of the 1,2-quinonediazide compound in the present invention is 100% by weight of the alkali-soluble novolac resin 100.
A range of 5 to 50 parts by weight is preferable with respect to parts by weight.

Further, the photosensitive resin composition of the present invention may contain a surfactant for preventing coatability, for example, triation (unevenness of film thickness) and improving developability. Further, the photosensitive resin composition of the present invention may contain a dye or pigment for reducing the influence of halation during exposure. In addition, if necessary, a storage stabilizer, a dissolution inhibitor, etc. can be added.

The photosensitive resin composition of the present invention is made into a solution,
A resist image is manufactured by forming a coating film on a semiconductor manufacturing substrate, exposing it, and developing it. The conditions of exposure and development are not limited.

Examples of the solvent used in this case include glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol alkyl ether acetates such as ethyl cellosolve acetate, diethylene glycols such as diethylene glycol monomethyl ether, and propylene glycol methyl ether acetate. Propylene glycol alkyl ether acetates, aromatic hydrocarbons such as toluene, ketones such as cyclohexanone, and esters such as methyl 2-hydroxypropionate can be used.

Examples of the developer include inorganic alkalis such as sodium hydroxide, primary amines such as ethylamine, secondary amines such as diethylamine, tertiary amines such as triethylamine, dimethylethanolamine and the like. Alkaline aqueous solutions in which alcohol amines, tetramethylammonium hydroxide, quaternary ammonium salts such as choline, or cyclic amines such as piperidine are dissolved are used.

[0015]

The present invention will be described below with reference to examples. In the examples, as the characteristics of the resin, the weight average molecular weight (Mw), the weight ratio of the low molecular weight component having a polystyrene reduced molecular weight of 2,000 or less, and the dissolution time in an alkali developing solution were mentioned.
Evaluation of these characteristics was performed by the following methods. Weight ratio of Mw to low molecular weight component; Hitachi Chemical Co., Ltd. GPC low molecular column, gel pack (R420 + R430
+ R440), the flow rate was 1.73 ml / min, the elution solvent was tetrahydrofuran, and the column temperature was room temperature at room temperature. Monodisperse polystyrene was used as a standard, and it was measured by Hitachi Ltd. liquid chromatogram 635A type HLC. H
In LC, the total resin and polystyrene equivalent molecular weight 2,0
The area ratio with respect to the part of 00 or less was calculated by the cutout weight method. Dissolution time in an alkali developing solution; a resin dissolved in ethyl cellosolve acetate was coated on a silicon wafer by a spin coater (coating film thickness was 1 μm), and this was 25
The solution was placed in a developing solution (tetramethylammonium hydroxide 2.38% by weight aqueous solution) at 0 ° C., and the time until the coating film disappeared was measured. The resist characteristics were evaluated by the following methods. Sensitivity: The LD-5010i reduction projection exposure machine manufactured by Hitachi, Ltd. was used to perform exposure by changing the exposure time, and then developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 60 seconds. Rinse with water and dry to form a resist pattern on the wafer.
The exposure dose for forming a line width of μm according to the dimension (hereinafter referred to as “optimum exposure dose”) was measured. Resolution: The size of the smallest resist pattern that can be resolved at the optimum exposure time was measured. Heat resistance: A wafer having a resist pattern formed thereon was placed on a hot plate, and the temperature at which the pattern began to deform was measured.

Synthesis Example 1 A separable flask equipped with a stirrer, a condenser and a thermometer was charged with m-cresol 328.1 g p-cresol 400.9 g 37% by weight formalin 372.2 g oxalic acid 2.24 g. Immerse the separable flask in an oil bath and adjust the internal temperature to 9
Polycondensation was carried out for 3 hours with stirring at 7 ° C. Then, the internal temperature was raised to 180 ° C. and the pressure inside the reaction vessel was simultaneously reduced to 10 to 20 mmHg to remove unreacted phenols, formaldehyde, water and oxalic acid. Next, the molten resin was poured into a metal vat to recover the resin (hereinafter, this resin is referred to as "resin 1"). Resin 1 Mw
Was 11,000, and the weight ratio of the low molecular weight component having a molecular weight (polystyrene-equivalent molecular weight; the same applies hereinafter) of 2,000 or less was 35% by weight. The dissolution time in an alkaline developer was 65 seconds / μm. 550 g of resin 1 was added to ethyl cellosolve acetate 1
A resin varnish was dissolved in 100 g, and 1000 g of toluene and 1000 g of hexane were mixed and stirred for 30 minutes and then allowed to stand to obtain a concentrated phase having a large amount of high molecular weight components in the lower layer portion. The concentrated phase was separated and dried under reduced pressure to obtain an alkali-soluble novolak resin having a reduced low molecular weight component (hereinafter, this resin is referred to as "resin 2"). When the Mw of resin 2 was measured,
It was 13,000, and the weight ratio of the low molecular weight component having a molecular weight of 2,000 or less was 3% by weight. The dissolution time in the alkaline developer was 1,000 seconds / μm or more.

Synthesis Example 2 In a separable flask similar to that used in Synthesis Example 1, m-cresol 324.5 g p-cresol 249.6 g 3,5-xylenol 116.5 g 37% by weight formalin 353.6 g oxalic acid 2.24 g. A resin was prepared, and a resin was obtained under the same synthesis conditions as in Synthesis Example 1 (hereinafter, this resin is referred to as “resin 3”). When the Mw of the resin 3 was measured, it was 5,500, and the weight ratio of the low molecular weight component having a molecular weight of 2,000 or less was 32% by weight. The dissolution time in an alkaline developer is 35 seconds / μm.
Met. Resin 3 was treated by the same dissolution fractionation method as in Synthesis Example 1 to obtain an alkali-soluble novolak resin having a reduced low molecular weight component (hereinafter, this resin is referred to as “resin 4”). When the Mw of the resin 4 was measured, it was 6,800, and the weight ratio of the low molecular weight component having a molecular weight of 2,000 or less was 4% by weight. The dissolution time in the alkaline developer was 1,000 seconds / μm or more.

Synthesis Example 3 A separable flask similar to that used in Synthesis Example 1 was charged with m-cresol 162.0 g p-cresol 324.0 g 2,5-xylenol 183.0 g 37% by weight formalin 384.3 g oxalic acid 2.24 g. A resin was prepared, and a resin was obtained under the same synthesis conditions as in Synthesis Example 1 (hereinafter, this resin is referred to as “resin 5”). When the Mw of the resin 5 was measured, it was 4,200, and the weight ratio of the low molecular weight component having a molecular weight of 2,000 or less was 28% by weight. The dissolution time in an alkaline developer is 42 seconds / μm.
Met. Resin 5 was treated by the same dissolution fractionation method as in Synthesis Example 1 to obtain an alkali-soluble novolak resin with reduced low molecular weight components (hereinafter, this resin is referred to as “resin 6”). When the Mw of the resin 6 was measured, it was 5,500, and the weight ratio of the low molecular weight component having a molecular weight of 2,000 or less was 3% by weight. The dissolution time in the alkaline developer was 1,000 seconds / μm or more.

Synthesis Example 4 A separable flask similar to that used in Synthesis Example 1 was charged with p-cresol 71.3 g, 37 wt% formalin 67.3 g water 200.0 g sodium hydroxide 1.2 g, and the separable flask was placed in an oil bath. Soaking and polycondensation were carried out for 2 hours while stirring at reflux temperature. Then, water was removed from the reaction system, 800 ml of diphenyl ether was added, and the mixture was stirred at 250 ° C. for 2 hours while removing condensed water. Next, after cooling, 500 ml of methanol was added to the reaction system.
Is charged, the precipitate is filtered off, washed with methanol and purified, and a phenolic cyclic compound (in the above structural formula (I), R ₁
= Give _{CH 3, R 2 = H,} n = 4) (hereinafter, to the phenol cyclic compound "cyclic compounds a").

Synthesis Example 5 A separable flask similar to that used in Synthesis Example 1 was charged with p-tert-butylphenol 100.0 g 37% by weight formalin 67.3 g water 200.0 g sodium hydroxide 1.2 g. To give a phenolic cyclic compound (hereinafter, this phenolic cyclic compound (in the above structural formula (I), R ₁ = C (C
H ₃ ) ₃ , R ₂ = H, and n = 4) are referred to as “cyclic compound b”). A separable flask similar to that used in Synthesis Example 1 was charged with 20.0 g of cyclic compound b, 0.7 g of nitromethane, 21.6 g of aluminum chloride and 400.0 g of toluene, and reacted at 40 ° C. for 3 hours. After that, ice water 2
The reaction was stopped by adding 00 g. After taking out the organic phase and removing the solvent with an evaporator, the phenolic cyclic compound (the above structural formula (I)
R ₁ = H, R ₂ = H, n = 4) was obtained (hereinafter, this phenolic cyclic compound is referred to as “cyclic compound c”).

Example 1 14 g of Resin 2, 6 g of cyclic compound c, 1.0 of 2,4,7-trihydroxy-2,4,4-trimethylflavan
4 g of a condensate of 2.3 mol of 1,2-naphthoquinonediazide-5-sulfonyl chloride (hereinafter referred to as "1,2-quinonediazide I") was dissolved in 80 g of ethyl cellosolve acetate, and the pore size was adjusted to 0. A positive resist was prepared by filtering with a 2 μm membrane filter. The obtained solution was applied on a silicon wafer using D-SPIN manufactured by Dainippon Screen Co., Ltd. and prebaked at 90 ° C. for 90 seconds to form a resist film having a thickness of 1.22 μm.
The resist characteristics were tested. The results are shown in Table 1.

Example 2 A positive resist was prepared in the same manner as in Example 1 except that the resin 4 was used instead of the resin 2, and the resist characteristics were tested. The results are shown in Table 1.

Example 3 A positive resist was prepared in the same manner as in Example 1 except that the resin 6 was used in place of the resin 2, and the resist characteristics were tested. The results are shown in Table 1.

Example 4 14 g of Resin 4, 6 g of cyclic compound c, 1.0 mol of di (4-hydroxyphenyl) [4- (1- (4-hydroxyphenyl) -1-methylethyl) phenyl] ethane After dissolving 4 g of a condensate with 3.0 mol of 1,2-naphthoquinonediazide-5-sulfonyl chloride (hereinafter, referred to as "1,2-quinonediazide II") in 80 g of ethyl cellosolve acetate, Example 1 and Similarly, a positive resist was prepared and the resist characteristics were tested. The results are shown in Table 1.

Example 5 16 g of Resin 4, 4 g of cyclic compound a, 4 g of 1,2-quinonediazide I and 80 g of ethyl cellosolve acetate
After being dissolved in, a positive resist was prepared in the same manner as in Example 1 and the resist characteristics were tested. The results are shown in Table 1.

Comparative Example 1 After dissolving 20 g of Resin 3 and 4 g of 1,2-quinonediazide I in 80 g of ethyl cellosolve acetate, a positive resist was prepared in the same manner as in Example 1 and the resist characteristics were tested. It was The results are shown in Table 1.

Comparative Example 2 After dissolving 20 g of Resin 5 and 4 g of 1,2-quinonediazide I in 80 g of ethyl cellosolve acetate, a positive resist was prepared in the same manner as in Example 1 and the resist characteristics were tested. It was The results are shown in Table 1.

Comparative Example 3 14 g of Resin 5, 6 g of cyclic compound c, 4 g of 1,2-quinonediazide I and 80 g of ethyl cellosolve acetate
After being dissolved in, a positive resist was prepared in the same manner as in Example 1 and the resist characteristics were tested. The results are shown in Table 1.

[0029]

[Table 1]

[0030]

The photosensitive resin composition of the present invention is excellent in sensitivity, resolution and heat resistance and is suitable as a positive resist for producing a highly integrated circuit, whereby a resist image having preferable characteristics can be obtained. You can

Claims (2)

[Claims] 1. A photosensitive resin composition containing an alkali-soluble novolac resin and a quinonediazide compound, wherein 30 to 100% by weight of a low molecular weight component having a polystyrene-equivalent molecular weight of 2000 or less of the alkali-soluble novolac resin is removed, and A photosensitive resin composition comprising a phenolic cyclic compound represented by the following structural formula (I). [Chemical 1] (R ₁ represents hydrogen, an alkyl group or an alkoxy group, R ₂ represents hydrogen, an alkyl group, an alkoxy group or a phenyl group, and R ₁ and R ₂ may be the same,
n represents an integer of 4 to 8. ) 2. A method for producing a resist image, which comprises exposing and developing a coating film of the photosensitive resin composition according to claim 1.