JPH0587822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive-working photoresist composition sensitive to radiation, and more particularly to a composition containing an alkali-soluble resin that is a component of a 1,2-naphthoquinonediazide-based positive photoresist. It is about improvement.

In recent years, 1,
2-Naphthoquinonediazide-based positive photoresists have come into widespread use. Conventionally, cresol novolac resins, vinyl phenol polymers, and the like have been known as binder polymers used in the photoresists, but resist films using these did not necessarily have sufficient dry etching resistance. The present inventors have conducted various studies on binder polymers for resists in order to further improve dry etching resistance, and have found that if a novolac resin containing α-naphthol as a condensation component is used, sensitivity and developability ( The present invention was completed based on the knowledge that a resist composition having a good residual film rate (residual film ratio) and improved dry etching resistance can be obtained.

That is, the gist of the present invention is to provide a positive photoresist composition comprising an alkali-soluble resin and a 1,2-naphthoquinone diazide compound, in which the alkali-soluble resin is a novolac type containing α-naphthol as a condensation component. A positive type photoresist composition characterized in that it contains a resin.

Next, the present invention will be explained in detail. The novolak resin contains α-naphthol as a condensation component, but it may also preferably be condensed with other phenols. Any of the above-mentioned phenols can be used as long as the novolak resin obtained by condensation with α-naphthol shows appropriate development characteristics as a positive resist, and examples include phenol, cresol, isopropylphenol,
Preferred examples include n-propylphenol and cresol. The novolak resin can be produced by condensing α-naphthol, if necessary with the above-mentioned phenols, and aldehydes in a known method using a known acid catalyst.

Any aldehyde may be used as long as it condenses with naphthols and phenols to give a novolac resin, but aliphatic aldehydes such as formaldehyde and acetaldehyde, or aromatic aldehydes such as benzaldehyde, 9-anthraldehyde, and naphthaldehyde are preferred. used for. Furthermore, mixtures of several aldehydes may also be used. The obtained novolak resin is preferably subjected to post-treatment such as reprecipitation purification as necessary.

Preferably, a novolac resin in which 40 to 95 mol% of the phenol and naphthol condensation components is α-naphthol, particularly one containing 40 to 95 mol% of α-naphthol and 60 to 5 mol% of p-cresol.
When α-naphthol is 40 mol% or less, the improvement in dry etching resistance is not remarkable, and when α-naphthol is 40 mol% or less,
In the above case, the solubility in the developer becomes excessive, resulting in film burr.

The α-naphthol-containing novolak resin used in the present invention is not limited to the use of one type alone, but may be used as a blend of two or more types.
Further, a known cresol novolak resin may be used in combination with this α-naphthol-containing novolak resin. At that time, 20% by weight or more of the novolak resin containing α-naphthol, preferably 40% by weight or more,
~90% by weight, the amount of known cresol novolak resin is 80% by weight or less, preferably 60 to 10% by weight.
They may be used in combination at a ratio of

Examples of the 1,2-naphthoquinonediazide-based compounds include the compounds described in JP-A-58-17112, but preferably 1,2-naphthoquinone diazide of 2,3,4-trihydroxybenzophenone.
2-diazide-5-sulfonic acid triester is mentioned. This is preferably as a quinone diazide group in 1 g of solid content of the photoresist composition.
It is preferable to use it in a range of 0.3 to 0.6 mmol.

The photoresist composition thus obtained is dissolved in a suitable solvent and coated on a substrate.
Examples of the solvent include cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ester solvents such as butyl acetate and amyl acetate, and highly polar solvents such as dimethylformamide and dimethyl sulfoxide. Can be mentioned. The solution may further contain dyes, coatability improvers, adhesion promoters, sensitivity improvers, and the like. A resist is formed by exposing a coating film formed on a base material in a pattern to electromagnetic waves having wavelengths below visible light, and developing the film.
Thereafter, the silicon oxide layer on the base material, for example, a silicon wafer, is dry etched. Shows several times higher resistance to dry etching processes than conventional products. This greatly improves the reliability of this process, and as a result, dramatically improves the yield of a semiconductor device manufacturing line in which this process is incorporated many times. Therefore, the industrial significance of the present invention is extremely large.

Next, the present invention will be specifically explained using Examples, but the present invention is not limited thereto unless it exceeds the gist thereof.

Example 1 α-naphthol 8.64g, para-cresol 4.32
g, formalin (37% formaldehyde aqueous solution)
A mixture consisting of 7.30 g and 0.15 g of oxalic acid dihydrate was heated at 80°C for 45 minutes and at 100°C for 25 minutes. Next, the mixture was washed with water at room temperature, and condensation was carried out while raising the temperature from 140°C to 200°C over 1 hour and 20 minutes under vacuum. 10g of the obtained novolak resin and 2,3,4
- 1.67 g of 1,2-naphthoquinone-2-diazide-5-sulfonic acid triester of trihydroxybenzophenone and 24 g of ethyl cellosolve acetate.
It was applied onto a silicon wafer containing 0.5 μm of silicon oxide using a spinner to a film thickness of 1.0 μm, and prebaked at 90° C. for 30 minutes. Next, pattern exposure was performed using a wafer stepper (DSW) manufactured by GCA Corp., and a developer (NMD manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used.
-3) at 25°C for 1 minute, and rinsed with water for 1 minute. The resulting images were evaluated using a scanning electron microscope and a dimension measuring machine called Runpass manufactured by Nippon Kogaku Kogyo Co., Ltd. The results showed that the practical sensitivity was 0.15 seconds (the exposure amount necessary to reproduce a line space of 1μ), and the residual film rate was 86% ( Good results were obtained with a resolution of 0.8 μm or less.

Next, the image-forming surface was etched using a plasma etching device manufactured by Plasma Thermo. The etching gas is 5% oxygen (O ₂ ) gas and 95
Etching was performed at 40° C. for 20 minutes at 750 μTorr using a gas mixture containing % of tetrafluoromethane (CF ₄ ), and the difference d in the resist film thickness before and after etching was measured.

On the other hand, for comparison, 70 mol% of metacresol and 30 mol% of para-cresol are used as novolac resins.
A comparative sample was prepared in the same manner as above using a resist synthesized using the same method as described above, dry etching was performed at the same time, and the difference in resist film thickness before and after etching was measured and used as d _ref . d _ref /d was 1.3, and the difference d in film thickness of the resist before and after dry etching in the present invention was smaller than d _ref of the resist when a novolak resin containing no naphthol component was used. This shows that it has excellent dry etching resistance.

Example 2 α-naphthol 50.4g, para-cresol 16.2
g, formalin (37% formaldehyde aqueous solution)
A novolac resin was synthesized in the same manner as in Example 1 using 36.5 g of oxalic acid dihydrate and 0.75 g of oxalic acid dihydrate. The obtained resin was dissolved in 180 g of acetone and reprecipitation treatment was performed twice by dropping 180 g of water, followed by vacuum drying to obtain a resin. Using this resin, image evaluation was performed in the same manner as in Example 1, and results equivalent to those in Example 1 were obtained. Furthermore, when dry etching resistance was evaluated, d _ref /d was 1.4.

Example 3 α-naphthol 11.52g, para-cresol 2.16
g, formalin 7.3g, oxalic acid dihydrate 0.15g
When a resin synthesized in the same manner as in Example 2 was used, except for using , the same evaluation was performed as in Example 2, and the image evaluation results were the same as in Example 1, with d _ref /d being 1.4.

Example 4 A resin synthesized in the same manner as in Example 2 was used, except that 10.08 g of α-naphthol, 4.08 g of m-isopropylphenol, 7.3 g of formalin, and 0.15 g of oxalic acid dihydrate was used, and the same evaluation was performed. Image evaluation was obtained. obtained the same results as in Example 1, and d _ref /d was 1.3.

Example 5 α-naphthol 5.76g, metacresol 1.08
g, paracresol 5.40g, formalin 7.3g,
When a resin synthesized in the same manner as in Example 2 was used, except that 0.15 g of oxalic acid dihydrate was used, and the same evaluation was performed, the image evaluation obtained the same results as in Example 1, and d _ref /d
was 1.2.

Example 6 Novolac resin 10 synthesized in Example 1
Evaluation was carried out in the same manner as in Example 1, except that instead of using 7 g of the novolac resin synthesized in Example 2, 3 g of the novolac resin synthesized using 60 mol% of meta-cresol, and 40 mol% of para-cresol. However, in image evaluation, the same results as in Example 1 were obtained, and d _ref /d was 1.3.

Example 7 Novolak resin 5 synthesized using 5 g of the resin synthesized in Example 3, 60 mol% of meta-cresol, and 40 mol% of para-cresol as a novolak-based resin.
When the evaluation was carried out in the same manner as in Example 1 except that g was used in a blended manner, the same image evaluation results as in Example 1 were obtained, and d _ref /d was 1.3.

Example 8 Novolak resin 7 synthesized using 3 g of the resin synthesized in Example 3, 60 mol% of meta-cresol, and 40 mol% of para-cresol.
When the evaluation was carried out in the same manner as in Example 1 except that g was used in a blended manner, the same results as in Example 1 were obtained in image evaluation, and d _ref /d was 1.2.

Example 9 In Example 1, the amount of formalin was 4.90 g,
Further, 4.2 g of 9-anthraaldehyde was added and a novolak resin was synthesized in the same manner. Example 1
A similar evaluation showed that d _ref /d was 1.5.

Example 10 A novolak resin was synthesized in the same manner as in Example 8, except that 3.2 g of β-naphthaldehyde was used instead of 9-anthraaldehyde. A similar evaluation showed that d _ref /d was 1.4.

Claims (1)

[Scope of Claims] 1. A positive photoresist composition comprising an alkali-soluble resin and a 1,2-naphthoquinonediazide-based compound, wherein the alkali-soluble resin contains a novolak-based resin containing α-naphthol as a condensation component. 1. A positive photoresist composition characterized by: 2 The condensation component of the novolac resin is at least α
- The composition according to claim 1, characterized in that it contains naphthol and p-cresol. 3. The novolac-based resin is a condensation component containing 40 to 95 mol% of α-naphthol and 5 to 60 mol% of p-cresol condensed with formaldehyde. Composition.