JP2527811B2 - Developer for positive resist - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel developer for positive resist. More specifically, the present invention relates to a positive resist developer which can be used for image formation of a positive resist containing an alkali-soluble novolak resin and a naphthoquinonediazide compound and which can remarkably improve contrast and depth of focus. .

2. Description of the Related Art Conventionally, semiconductor integrated circuit devices, masks for manufacturing integrated circuits,
When manufacturing printed wiring boards, etc., the base substrate is subjected to selective processing such as etching or diffusion treatment, and at this time, for the purpose of selectively protecting the unprocessed part of the base substrate. A protective film made of a resist sensitive to actinic rays such as ultraviolet rays, X-rays, and electron rays is provided on the base substrate.

As a method of providing a protective film made of such a resist on a base substrate, first, a resist film is formed on the substrate, and then this film is selectively irradiated with an actinic ray, and then developed. Is used. The resist is classified into a positive type and a negative type. In the former, the irradiated part is dissolved in the developing solution, but the unirradiated part is not dissolved, while the latter is the opposite type.

By the way, in recent years, the processing size has been miniaturized in the manufacture of electronic parts, and as the resist, a positive type having excellent resolution has been widely used. A typical example of this positive resist is a combination of an alkali-soluble novolac resin and a naphthoquinonediazide compound. An alkaline aqueous solution is used as a developer for the alkali-soluble novolac resin-naphthoquinonediazide positive resist, and an organic alkaline aqueous solution such as tetramethylammonium hydroxide or choline is usually used. However, these developers are useful as developers for positive type resists, but they have a drawback that the difference in solubility between the active ray irradiated portion and the non-irradiated portion is small and the contrast is low.
Therefore, the obtained resist pattern is easy to pull, it is not possible to obtain a resist pattern excellent in dimensional stability, especially as a developer for obtaining a resist pattern of submicron order is not practical, It is becoming impossible to deal with the miniaturization of the processing size in the field of semiconductor integrated circuit device manufacturing.

On the other hand, the microfabrication in the manufacturing field of semiconductor integrated circuit devices is greatly affected by the improvement of the irradiation technology in photolithography, and especially by the reduction projection exposure apparatus using a short wavelength such as i-line (365 nm) as a light source. Although it has become possible to easily obtain a submicron-order resist pattern, the problem of depth of focus has been newly highlighted.

The problem of the depth of focus, that is, the problem of the depth of focus conversely decreasing with the improvement of the resolution, is unavoidable as long as the irradiation device of the optical system is used. Even if the depth is small and the width of the light intensity distribution is narrow, an effective resist pattern can be obtained.

Therefore, hitherto, various positive resist developers for the purpose of improving contrast, for example, 1,2-quinonediazide positive resist developers comprising a mixture of a cyclic amine and water (JP-A-57-30832). JP-A-60-179738), and a positive resist developer comprising an aqueous solution of a cyclic quaternary ammonium hydroxide compound have been proposed. However, the former developer is α, β
-Although effective for positive resists using copolymers of ethylenically unsaturated carboxylic acids, it has the drawback that it cannot be applied to positive resists using novolac resins, which are widely used as positive resists at present. are doing. On the other hand, the latter developing solution is an aqueous solution of a cyclic quaternary ammonium hydroxide compound obtained by N-methylating a cyclic nitrogen compound and further ion-exchanging it, and therefore the preparation process of the developing solution is extremely complicated. However, there is a drawback that it is difficult to obtain a resist having a stable developing action, and a stable resist pattern cannot be formed, which is not practical.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention contains an alkali-soluble novolac resin and a naphthoquinonediazide compound that overcome such drawbacks of the conventional positive resist developers, have high contrast, and improve the depth of focus. It was made for the purpose of providing a positive resist developing solution.

Means for Solving the Problems As a result of intensive studies to develop a positive resist developer having such preferable properties, the present inventors have found that a specific organic quaternary ammonium hydroxide compound is contained. It was found that an aqueous solution prepared by adding a specific alkali-soluble cyclic nitrogen compound to the above-mentioned solution can meet the above-mentioned object, and the present invention has been completed based on this finding.

That is, the present invention is a developer comprising an organic alkali aqueous solution for a positive resist containing an alkali-soluble novolac resin and a naphthoquinonediazide compound,
As the organic alkaline aqueous solution, N-hydroxyethylpiperazine and N-methyl-4-piperidone are added to an aqueous solution containing at least one organic quaternary ammonium hydroxide compound selected from tetramethylammonium hydroxide and choline. , 1,3-dimethyl-2-imidazolicinone, pyridine, 2-hydroxyethylpiperidine,
N-methylpiperazine, 2-methylimidazole, 4-
(2-hydroxyethyl) morpholine, 1- (2-hydroxyethyl) -2-pyrrolidone, 2-hydroxyethylpyridine, 2-hydroxyethylpiperazine and 2-
It is intended to provide a developer for a positive resist, which is prepared by adding at least one alkali-soluble cyclic nitrogen compound selected from aminothiazole.

 Hereinafter, the present invention will be described in detail.

The organic quaternary ammonium hydroxide compound used in the developing solution of the present invention is tetramethylammonium hydroxide or choline or both, and its concentration, that is, the content ratio relative to the total amount of the developing solution is usually 1.
It is selected in the range of 0 to 10.0% by weight, preferably 1.5 to 7.0% by weight. If the concentration is less than 1.0% by weight, the sensitivity may be lowered, and if it exceeds 10.0% by weight, the solubility is increased and the film loss of the unirradiated portion tends to increase, which is not preferable.

The developer of the present invention is characterized in that a specific alkali-soluble cyclic nitrogen compound is added to an aqueous solution containing the organic quaternary ammonium hydroxide compound, and the alkali-soluble cyclic nitrogen compound is N-hydroxyethylpiperazine. , N-methyl-4-piperidone, 1,3-dimethyl-
2-imidazolidinone, pyridine, 2-hydroxyethylpiperidine, N-methylpiperazine, 2-methylimidazole, 4- (2-hydroxyethyl) morpholine,
1- (2-hydroxyethyl) -2-pyrrolidone, 2-
It is selected from hydroxyethylpyridine, 2-hydroxyethylpiperazine, and 2-aminothiazole, and these may be used alone or in combination of two or more kinds. Among them, N-hydroxyethylpiperazine, N-methyl-4-piperidone and 1,
3-Dimethyl-2-imidazolidinone is preferable because it is excellent not only in improving contrast and depth of focus but also in removing scum.

The concentration of the alkali-soluble cyclic nitrogen compound in the developer of the present invention is usually 0.1 to 10% by weight, preferably 0.3 to
It is selected in the range of 5.0% by weight. If this concentration is less than 0.1% by weight, the object of the present invention is not sufficiently achieved, and if it exceeds 10% by weight, the solubility in unirradiated portions tends to be high, which makes it difficult to obtain a good resist pattern, which is not preferable. .

The positive resist intended for the developer of the present invention contains an alkali-soluble novolac resin and a naphthoquinonediazide compound, and the alkali-soluble novolac resin is obtained from, for example, phenol, cresol or xylenol and aldehydes. Anything that can be used can be used. Particularly preferred alkali-soluble novolac resins include cresol novolac resins, specifically those obtained from a mixed cresol of 10-45% by weight of m-cresol and 90-55% by weight of p-cresol. By using such a cresol novolac resin, a resist pattern having excellent dimensional accuracy and dimensional stability can be obtained.

Examples of the naphthoquinonediazide compound include, for example, partial or complete esterification of sulfonic acid of orthonaphthoquinonediazide and a compound having a phenolic hydroxyl group or an amino group, or partial or complete amidation thereof, and the above-mentioned phenolic compound. Examples of the compound having a hydroxyl group or an amino group include polyhydroxy such as 2,3,4-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, and 2,3,4,4'-tetrahydroxybenzophenone. Benzophenone or alkyl gallate, aryl gallate, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl Examples thereof include ether, gallic acid, gallic acid esterified or etherified with some hydroxyl groups remaining, aniline, and p-aminodiphenylamine.

In the positive resist intended for the developer of the present invention, the naphthoquinonediazide compound is preferably added in a proportion of usually 10 to 40% by weight with respect to the alkali-soluble novolac resin, and this amount is 10% by weight. If it is less than 40% by weight, a resist pattern having an excellent cross-sectional shape is difficult to obtain, which is not practical, and if it exceeds 40% by weight, the sensitivity tends to remarkably decrease, which is not preferable.

The positive resist targeted by the developer of the present invention is not particularly limited as long as it contains an alkali-soluble novolac resin and a naphthoquinonediazide compound, and any one can be selected and used. That is, the actinic rays that are sensitive are not particularly limited, and positive resists that are sensitive to electron rays and x-rays can be used in addition to those sensitive to actinic rays such as ultraviolet rays and deep ultraviolet rays. For example, as a positive type electron beam resist, m
-Cresol novolac resin obtained from mixed cresol of 10-45% by weight of cresol and 90-55% by weight of p-cresol and 2,3,4-trihydroxybenzophenone, 2,
2 ', 4,4'-tetrahydroxybenzophenone and 2,3,
An naphthoquinone-1,2-diazide-4-sulfonic acid ester of at least one polyhydroxybenzophenone selected from 4,4'-tetrahydroxybenzophenone can be preferably used. Among such positive type electron beam resists, those having an average esterification degree of 60% or more of the ester are particularly preferable because a resist pattern having an extremely excellent image contrast can be formed.

Further, the positive resist containing the alkali-soluble novolac resin and naphthoquinonediazide compound,
It is advantageous to dissolve them in a suitable solvent in the required amount and to use them in the form of a solution.

Examples of such a solvent include acetone, methyl ethyl ketone, cyclohexane, ketones such as methyl isoamyl ketone, ethylene glycol, propylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate,
Alternatively, polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monoisopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof; cyclic ethers such as dioxane; methyl acetate, ethyl acetate, acetic acid Esters such as butyl may be mentioned. These may be used alone or in combination of two or more.

Effects of the Invention The positive resist developer of the present invention is one in which an alkali-soluble cyclic nitrogen compound is added to an organic alkali aqueous solution, and in the development processing of a positive resist containing an alkali-soluble novolac resin and a naphthoquinonediazide compound, Because the contrast can be improved,
It is possible to provide a resist pattern having an extremely good cross-sectional shape, and as a result, it is possible to improve the depth of focus. Further, the developer of the present invention has an effect of removing scum and can be very effectively used for forming a fine resist pattern.

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.

Examples 1 to 7 and Comparative Example 1 A developer was prepared by adding an alkali-soluble cyclic nitrogen compound as shown in the table to a tetramethylammonium hydroxide aqueous solution having each concentration shown in the another table.

On the other hand, the weight ratio of m-cresol and p-cresol is
Mixing at a ratio of 40:60, formalin was added thereto, 100 parts by weight of cresol novolac resin obtained by condensation in a conventional manner using an oxalic acid catalyst, and naphthoquinone-1,2-diazide-5-sulfonic acid A positive resist was prepared by dissolving 30 parts by weight of 2,3,4-trihydroxybenzophenone ester in 390 parts by weight of ethylene glycol monoethyl ether acetate and filtering the resulting solution using a 0.2 μm membrane filter. Then, this positive resist was applied onto a 4-inch silicon wafer treated with hexamethyldisilazane by a spinner to obtain 1.35 μm.
After being applied thickly, it was pre-baked on a hot plate at 110 ° C. for 90 seconds, and exposed through a test chart reticle using a reduction projection type exposure apparatus NSR-1505G4D (manufactured by Nikon Corporation). Next, using a stationary paddle type developing device, a developing treatment was carried out at a temperature of 23 ° C. for 65 seconds using the developer prepared as described above, followed by a rinse treatment with pure water for 30 seconds and then drying. The resist pattern thus obtained was observed, and the results are shown in the table.

Example 8 TSMR-8800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive resist containing a cresol novolak resin and a naphthoquinonediazide compound, was used, and a developing solution was 4.60.
N-Hydroxyethylpiperazine in wt% choline aqueous solution
A resist pattern was formed in the same manner as in Example 1 except that 2.5% by weight was used.
At 160 ms, the profile shape was extremely good as shown in Fig. 1 (a). Further, after the development processing, generation of scum on the substrate could not be confirmed at all.

For comparison, when a resist pattern was similarly formed using the developer containing no N-hydroxyethylpiperazine, the sensitivity was 150 ms and the profile shape was as shown in FIG. 1 (b). It was such a bad thing. Further, it was confirmed that scum was generated on the substrate after the development processing.

Example 9 A developer (A) consisting of a 2.38 wt% tetramethylammonium hydroxide aqueous solution and a developer (B) prepared by adding 2.5 wt% of N-hydroxyethylpiperazine to a 2.14 wt% tetramethylammonium hydroxide aqueous solution. Using each developing solution, a resist pattern was formed in the same manner as in Example 1, and the focus depth in the 1.0 μm pattern was examined. The results are shown in FIGS. 2 and 3, respectively. From FIG. 3, it was confirmed that the developer (B) of the present invention has a large focus margin.

Example 10 TSMR-8800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive resist containing a cresol novolac resin and a naphthoquinonediazide compound, is used, and the developer is 2.
A resist pattern was formed in the same manner as in Example 1 except that 1.5% by weight of 1,3-dimethyl-2-imidazolidinone was added to a 10% by weight tetramethylammonium hydroxide aqueous solution. At 140 ms, the profile shape was extremely good as shown in Fig. 1 (a). Further, no scum was observed on the substrate after the development treatment.

Example 11 40:60 by weight ratio of m-cresol and p-cresol
100 parts by weight of cresol novolac resin obtained by good condensation in a conventional manner using an oxalic acid catalyst and naphthoquinone-1,2 of 2,3,4-trihydroxybenzophenone. By dissolving 17 parts by weight of diazide-4-sulfonic acid ester (average degree of esterification 75%) and 350 parts by weight of ethylene glycol monoethyl ether acetate, and filtering the resulting solution using a 0.2 μm membrane filter. A positive electron beam resist was prepared. Next, this positive type electron beam resist was coated on a 4-inch silicon wafer treated with hexamethylsilazane to a thickness of 0.5 μm by a spinner, and then prebaked at 80 ° C for 90 seconds on a hot plate, HHS-2R manufactured by Hitachi Ltd.
After selectively irradiating an electron beam with an accelerating voltage of 20 kV using 1.8 wt% tetramethylammonium hydroxide aqueous solution, 1.0 wt% of 2-hydroxyethylpyridine
And 2.0% by weight of 1,3-dimethyl-2-imidazolidinone were added to the resist to dissolve and remove the electron beam-irradiated portion by immersion development at 23 ° C. for 90 seconds using a developing solution. Got the pattern. As a result, a 0.5 μm resist pattern having a good cross-sectional shape as shown in FIG. 1 (a), which stands substantially vertically from the silicon wafer surface, was obtained, and the image contrast was extremely excellent.
The sensitivity of the residual film was 18 μC / cm ² . No scum was observed in the electron beam irradiated area after development.

Example 12 Instead of naphthoquinone-1,2-diazide-4-sulfonic acid ester of 2,3,4-trihydroxybenzophenone in Example 11 (average degree of esterification 75%), 2,2 ',
Examples except that naphthoquinone-1,2-diazide-4-sulfonic acid ester of 4,4'-tetrahydroxybenzophenone (average esterification degree 75%) was used and the developing conditions were changed to 23 ° C and 120 seconds. A resist pattern was obtained by exactly the same operation as in 11. As a result, a 0.5 μm resist pattern having a good cross-sectional shape as shown in FIG. 1 (a), which stands substantially vertically from the silicon wafer surface, was obtained, and the image contrast was extremely excellent. The sensitivity of the residual film was 18 μC / cm ² . Further, no scum was observed in the electron beam irradiated portion after development.

Comparative Example 2 A resist pattern was obtained in the same manner as in Example 11 except that a 2.38 wt% tetramethylammonium hydroxide aqueous solution was used as the developing solution. As a result, a resist pattern having a bad profile as shown in FIG. 1 (b) was obtained, and the sensitivity at 90% residual film was 40 μC / cm ² . Further, it was confirmed that scum was generated in the electron beam irradiated portion after development.

Comparative Example 3 A resist pattern was obtained in the same manner as in Example 12, except that a 2.38 wt% tetramethylammonium hydroxide aqueous solution was used as the developing solution. As a result, a resist pattern having a bad profile as shown in FIG. 1 (b) was obtained, and the sensitivity at 90% residual film was 80 μC / cm ² . Further, it was confirmed that scum was generated in the electron beam irradiated portion after development.

[Brief description of drawings]

FIG. 1 is a cross-sectional shape diagram of a resist pattern obtained after development processing, and FIGS. 2 and 3 are resist pattern dimensions and focus when using a conventional developer and the developer of the present invention, respectively. It is the graph which plotted the relationship with depth by changing exposure amount.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-57-30832 (JP, A) JP-A-60-179738 (JP, A) JP-A 64-72155 (JP, A) JP-A 64-- 19345 (JP, A)

Claims (3)

(57) [Claims] 1. A developer comprising an organic alkaline aqueous solution for a positive resist containing an alkali-soluble novolac resin and a naphthoquinonediazide compound, wherein the organic alkaline aqueous solution is selected from tetramethylammonium hydroxide and choline. In an aqueous solution containing at least one organic quaternary ammonium hydroxide compound,
N-hydroxyethylpiperazine, N-methyl-4-piperidone, 1,3-dimethyl-2-imidazolidinone, pyridine, 2-hydroxyethylpiperidine, N-methylpiperazine, 2-methylimidazole, 4- (2-hydroxy Ethyl) morpholine, 1- (2-hydroxyethyl) -2-pyrrolidone, 2-hydroxyethylpyridine, 2-hydroxyethylpiperazine and at least one alkali-soluble cyclic nitrogen compound selected from 2-aminothiazole are added. A developer for a positive resist, characterized in that 2. The developer according to claim 1, wherein the concentration of the organic quaternary ammonium hydroxide compound is in the range of 1.0 to 10.0% by weight. 3. The concentration of the alkali-soluble cyclic nitrogen compound is 0.
The developing solution according to claim 1 or 2, which is in the range of 1 to 10% by weight.