JPH02160246A - Developing solution for positive type resist - Google Patents

Abstract

PURPOSE:To stably form a resist pattern high in contrast by adding an alkali- soluble cyclic nitrogen compound in an aqueous organic alkaline solution. CONSTITUTION:It is preferred to use as the aqueous organic alkaline solution the one containing tetramethyl ammonium hydroxide or/and choline in a concentration of, usually, 1.0 - 10wt.%, preferably, 1.5 - 7.5wt.%, and the alkali-soluble cyclic nitrogen compound is added to the solution in an amount of, usually, 0.1 - 10wt.%, preferably, 0.3 - 5.0wt.% of the solution, thus permitting contrast to be enhanced, accordingly, a resist pattern extremely good in the sectional form to be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel developer for positive resists. More specifically, the present invention relates to a developer for a positive resist, which is used for image formation of a positive resist containing an alkali-soluble novolak resin and a naphthoquinone diazide compound, and is capable of significantly improving contrast and depth of focus. .

Conventional Technology Conventionally, when manufacturing semiconductor integrated circuit elements, masks for integrated circuit manufacturing, printed wiring boards, etc., on the base substrate,
For example, selective processing such as etching or diffusion processing is performed, and at this time, in order to selectively protect the unprocessed portions of the underlying substrate, it is sensitive to active rays such as ultraviolet rays, X-rays, and electron beams. A protective film made of resist is provided on the base substrate.

A method for providing a protective film made of such a resist on a base substrate is to first form a resist film on the substrate, then selectively irradiate this film with actinic radiation, and then develop it. is used. There are two types of resist: positive type and negative type; in the former type, the irradiated area dissolves in a developer but the unirradiated area does not dissolve, while in the latter type, the opposite type exists.

Incidentally, in recent years, processing dimensions have become increasingly fine in the manufacture of electronic components, and positive-type resists with excellent resolution are increasingly being used. A typical positive resist is a combination of an alkali-soluble novolac resin and a naphthoquinone diazide compound. For this alkali-soluble novolac resin-naphthoquinone diazide positive resist, an alkaline aqueous solution is used as a developer, and for example, an organic alkali aqueous solution such as tetramethylammonium hydroxide or choline is usually used. However, although these developers are useful as developers for positive resists, they have the disadvantage that the difference in solubility between the active ray irradiated area and the non-irradiated area is small and the contrast is low.

As a result, the resulting resist pattern tends to have streaks, making it impossible to obtain a resist pattern with excellent dimensional stability, and it is not practical as a developing solution, especially for obtaining submicron order resist patterns. It has become impossible to cope with the shrinking of processing dimensions in the field of semiconductor integrated circuit device manufacturing.

On the other hand, improvements in irradiation technology in photolithography have had a major impact on microfabrication in the field of manufacturing semiconductor integrated circuit devices, and in particular, reduction projection exposure equipment that uses short wavelengths such as i-line (365I1m) as a light source has greatly influenced microfabrication. Although it has become possible to easily obtain resist patterns on the order of submicrons, the problem of depth of focus has recently come into focus.

This problem of depth of focus, along with the improvement of resolution,
The problem of reduced depth of focus is unavoidable as long as an optical irradiation device is used, but by using a developer with excellent contrast, it can be reduced even if the depth of focus is small and the width of the light intensity distribution is narrow. , an effective resist pattern can be obtained.

Therefore, various positive resist developers have been developed for the purpose of improving contrast, such as a 1,2-quinonediazide positive resist developer containing a mixture of a cyclic amine and water (Japanese Patent Application Laid-open No. 57-30832 Publication No.),
A positive resist developer comprising an aqueous solution of a cyclic quaternary ammonium hydroxide compound (Japanese Unexamined Patent Publication No. 179738/1983) has been proposed.

However, although the former developer is effective for positive resists using a copolymer of a, β-ethylenically unsaturated carboxylic acid, it is not suitable for use with novolak resins, which are currently widely used as positive resists. It has the disadvantage that it cannot be applied to positive resists. On the other hand, the latter developer is an aqueous solution of a hydroxylated quaternary ammonium compound obtained by N-methylating a cyclic nitrogen compound and then ion-exchanging it, so the preparation process for the developer is extremely complicated. , it is difficult to obtain a stable developing action, and a stable resist pattern cannot be formed, so it is not practical.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of the conventional positive resist developer, and contains an alkali-soluble novolac resin and a naphthoquinone diazide compound that provides high contrast and improves the depth of focus. The purpose of this invention is to provide a developer for positive-type resists.

Means for Solving the Problems As a result of extensive research in order to develop a positive resist developer having such favorable properties, the present inventors added an alkali-soluble cyclic nitrogen compound to an organic alkaline aqueous solution. The present inventors have discovered that a system suitable for the above-mentioned purpose and have completed the present invention based on this knowledge.

That is, the present invention is characterized in that, in a developer comprising an organic alkaline aqueous solution for positive resists containing an alkali-soluble novolak resin and a 7-toquinone diazide compound, an alkali-soluble cyclic nitrogen compound is added to the organic alkaline aqueous solution. The present invention provides a developer solution for positive resists.

The present invention will be explained in detail below.

The organic alkaline aqueous solution used as the developer of the present invention is not particularly limited as long as it contains an organic alkaline compound, but it may be tetramethylammonium hydroxide or choline, or both, which are conventionally used in the semiconductor manufacturing field. An organic alkaline aqueous solution containing is preferably used. At this time, the concentration of the alkaline aqueous solution is usually 1.0 to 1000% by weight, preferably 1.
．． It is selected in a range of 5 to 7.0% by weight. This concentration is 1.
If it is less than 0% by weight, the sensitivity may be lowered, and if it exceeds 10% by weight, the solubility will increase and film loss in unirradiated areas will tend to increase, which is not preferable.

The developer of the present invention is characterized in that an alkali-soluble cyclic nitrogen compound is added to the organic alkali aqueous solution, and examples of the alkali-soluble cyclic nitrogenated metal compound include pyrrole, pyrrolidine, pyrrolidone, indole, pyridine, and pyridone. , piperidone, piperidine, quinoline,
Examples include pyrazole, imidazole, imidazolidine, imidazolidinone, pyridazine, pyrimidine, pyrazine, piperazine, triazole, oxazole, morpholine, thiazole, and derivatives thereof. Specifically, 2-hydroxyethylpyridine, N-methylpiperazine, N-hydroxyethylpiperazine, 2-hydroxyethylpiperazine, 2-methylimidazole, 4-(
2-hydroxyethyl) mol 7 oline, 1-(2-hydroxyethyl)pyro, lydone, N-methyl-4-piperidone, 2-aminothiazole, l,3-dimethyl-2-
Examples include imidazolidinone. These may be used alone or in combination of two or more. Among these, N-hydroxyethylpiperazine, N-methyl-4-piperidone and 1,3-
Dimethyl-2-imidazolidinone is preferable because it not only improves contrast and depth of focus but also has an excellent scum removal effect.

The amount of these alkali-soluble cyclic nitrogen compounds added is usually 0.1 to 1011% by weight based on the organic alkali aqueous solution.
, preferably in the range of 0.3 to 5.0% by weight.

If the amount added is less than 0.11% by weight, the object of the present invention cannot be fully achieved, and if it exceeds 10% by weight, the solubility in unirradiated areas tends to increase, making it difficult to obtain a good resist pattern, so it is preferable. do not have.

The positive resist targeted by the developer of the present invention contains an alkali-soluble novolac resin and a naphthoquinone diazide compound. The alkali-soluble novolac resin may be obtained from, for example, phenol, cresol, xylenol, etc., and aldehydes. You can use what is available. Particularly preferred alkali-soluble novolak resins include cresol novolac resins, specifically those obtained from a mixed cresol of l-cresol lO to 45% by weight and p-cresol 90 to 55% by weight. By using such Talesol novolak resin, a resist pattern with excellent dimensional accuracy and dimensional stability can be obtained.

In addition, examples of naphthoquinone diazide compounds include,
Examples include those obtained by partially or completely esterifying or partially or completely amidating the sulfonic acid of orthonaphthoquinone diazide and a compound having a 7-enolic hydroxyl group or an amino group. For example, polyhydroxybenzophenones such as 2.3.4-) hydroxybenzophenone, 2.2', 4.4'-tetrahydroxybenzophenone, 2.3.4.4'-tetrahydroxybenzophenone, or alkyl gallates. , aryl gallate, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A1 naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether, gallic acid, esterified with some hydroxyl groups remaining, or Examples include etherified gallic acid, aniline, p-aminodiphenylamine, and the like.

In the positive resist to which the developer of the present invention is applied, the naphthoquinonediazide compound is preferably blended in a proportion of usually 10 to 40% by weight based on the alkali-soluble novolak resin, and this amount is 10% by weight. If it is less than 40% by weight, it is difficult to obtain a resist pattern with an excellent cross-sectional shape and is not practical, and if it exceeds 40% by weight, the sensitivity tends to decrease significantly, 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 novolak resin and a naphthoquinone diazide compound, and any resist can be selected and used. That is, there is no particular restriction on the active rays to which the resist is sensitive, and in addition to those sensitive to active rays such as ultraviolet rays and far ultraviolet rays, positive resists that are sensitive to electron beams and X-rays can also be used. For example, as a positive electron beam resist, m-
Cresol 10-45% by weight and p-cresol 90-5%
Cresol novolak resin obtained from mixed cresol with 5% by weight of 2.3.4-) hydroxybenzophenone, 2.2', 4.4'-tetrahydroxybenzophenone and 2.3.4.4'- A compound selected from tetrahydroquine benzophenones and a naphthoquinone-1,2-diazide-4-sulfonic acid ester of at least one polyhydroxybenzophenone can be preferably used.

Among such positive electron beam resists, those in which the average degree of esterification of the ester is 60% or more are particularly suitable because they can form a resist pattern with extremely excellent image contrast.

Further, the positive resist containing the alkali-soluble novolak resin and naphthoquinonediazide compound is advantageously used in the form of a solution by dissolving them in required amounts in a suitable solvent.

Examples of such solvents include acetone, ketones such as methyl ethyl ketone, cyclohexanone, isoamyl ketone, ethylene glycol, propylene glycol,
Polyhydric alcohols and derivatives thereof such as ethylene glycol monoacetate, diethylene glycol or monomethyl ether, monoethyl ether, monopropyl ether, monoisopropyl ether, monobutyl ether, monophenyl ether; cyclic ethers such as dioxane : Examples include esters such as methyl acetate, ethyl acetate, and butyl acetate. 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 a solution containing an alkali-soluble cyclic nitrogen compound added to an organic alkaline aqueous solution, and is effective in developing a positive resist containing an alkali-soluble novolac resin and a naphthoquinone diazide compound. Since the contrast can be improved, it is possible to provide a resist pattern with an extremely good cross-sectional shape, and as a result, the seven-occasion depth can be improved. Furthermore, since the developer of the present invention also has a scum removal effect, it can be used extremely effectively for forming fine resist patterns.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Examples 1 to 7, Comparative Example 1 A developing solution was prepared by adding an alkali-soluble cyclic nitrogen compound as shown in the table to a tetramethylammonium hydroxide aqueous solution having various concentrations shown in the table.

On the other hand, the weight ratio of m-cresol and p-cresol was 4
100 parts by weight of Talesol novolac resin obtained by mixing in a ratio of 0 to 60, formalin added thereto, and condensation using an oxalic acid catalyst in a conventional manner, and naphthoquinone-1,2
A solution obtained by dissolving 30 parts by weight of 2.3.4-toIJ hydroxybenzophenone ester of -diazide-5-sulfonic acid in 390 parts by weight of ethylene glycol heptanoethyl ether acetate was filtered through a 0.2 μm membrane filter. A positive resist was prepared by filtering using The film was prebaked at 110° C. for 90 seconds, and exposed through a test chart reticle using a reduction projection exposure device N5R-1505G4D (manufactured by Kon Co., Ltd.).

Next, using a stationary paddle type developing device, development was performed at a temperature of 23° C. for 65 seconds using the developer prepared as described above, followed by rinsing with pure water for 30 seconds and drying. The resist pattern thus obtained was observed and the results are shown in the table.

Example 8 TSMR-8800, a positive resist containing Talesol novolac resin and 7-toquinone diazide compound
(manufactured by Tokyo Ohka Kogyo Co., Ltd.), and the developer used was a 4.60 wt% choline aqueous solution to which 2.5 wt% N-hydroxyethylpiperazine was added. When a resist pattern was formed in the same manner, the sensitivity was 16011s and the profile shape was the first.
The results were extremely good as shown in Figure (a).

Further, after the development process, no scum was observed on the substrate.

For comparison, when a resist pattern was formed in the same manner using the developer without the addition of N-hydroxyethylpiperazine, the sensitivity was 150 m5 and the profile shape was as shown in Figure 1(b). It was so bad that it made me feel bad. Furthermore, after the development process, scum was observed on the substrate.

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

Example IO TSMR-880 is a positive resist containing Talesol novolak resin and 7-toquinone diazide compound
0 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), and as a developer, 1.5% by weight of 1.3-dimethyl-2-imidazolidinone was added to a 2.10% by weight tetramethylammonium hydroxide aqueous solution. Example 1 except that
When a resist pattern was formed in the same manner as above, the sensitivity was 14 ks and the profile shape was extremely good as shown in FIG. 1(a). Furthermore, no scum was observed on the substrate after development.

Example 1 m-cresol and p-cresol in a weight ratio of 40:6
100 parts by weight of cresol novolak resin obtained by mixing in a ratio of 0.0 and formalin added thereto and condensing in a conventional manner using an oxalic acid catalyst, and naphthoquinone-1 of 2,3.4-t-lyhydroxybenzophenone. , 2-diazide-4-sulfonic acid ester (average degree of esterification 75%)
17 parts by weight of ethylene glycol monoethyl ether acetate and 350 parts by weight of ethylene glycol monoethyl ether acetate.
A positive electron beam resist was prepared by filtration using a No. m membrane filter. Next, this positive electron beam resist was applied to a thickness of 0.5 nm on a 4-inch silicon wafer treated with hexamethylsilazane using a spinner, and then prebaked on a hot plate at 80°C for 90 seconds to form a new Hitachi HH3- 20kV using 2R
After selectively irradiating with an electron beam at an accelerating voltage of
1.0% by weight of 2-hydroxyethylpyridine and 1.3-
By performing immersion development at 23° C. for 90 seconds using a developer obtained by adding 2.0% by weight of dimethyl-2-imidazolidinone, the electron beam irradiated portion was dissolved and removed to obtain a resist pattern. . As a result, a 0.5 μm resist pattern with a good cross-sectional shape as shown in FIG. , 90
The sensitivity in terms of % film remaining was l 8 /JC/C11''. No scum was observed in the electron beam irradiated area after development.

Example 12 Instead of naphthoquinone-1,2-diadi F-4-sulfonic acid ester of 2,3,4-trihydroxybenzophenone (average degree of esterification 75%) in Example 11, 2.2', 4. Example 8 except that 7-toquinone-1,2-diazide-4-sulfonic acid ester of 4'-tetrahydroxybenzophenone (average degree of esterification 75%) was used and the development conditions were changed to 23°C and 120 seconds. A resist pattern was obtained in exactly the same manner as above. As a result, a resist pattern of 0.5 ttm was obtained, which had a good cross-sectional shape as shown in Figure 1(a), standing almost perpendicularly from the silicon urethane surface, and had extremely excellent image contrast. The sensitivity at 90% remaining film was 18 μC/crs. Further, no scum was observed in the electron beam irradiated area after development.

Comparative Example 2 In Example 11, a 2.38% by weight aqueous tetramethylammonium hydroxide solution was used as the developer.
A resist pattern was obtained by the same operations as in Example 8 except for this. As a result, a resist pattern with a poor profile shape as shown in FIG. 1(b) was obtained, and 9
The sensitivity at 0% residual film was 40 μC/cm''. Also, scum was observed in the electron beam irradiated area after development.

Comparative Example 3 A resist pattern was obtained in exactly the same manner as in Example 9 except that a 2.38% by weight aqueous tetramethylammonium hydroxide solution was used as the developer in Example 12. As a result, a resist pattern with a poor profile shape as shown in FIG.
The sensitivity at % remaining film was 80μC/cm''.In addition, scum was observed in the electron beam irradiated area after development.
;.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the resist pattern obtained after the development process, and FIGS. 2 and 3 show the resist pattern dimensions and focus when using a conventional developer and the developer of the present invention, respectively. It is a graph plotting the relationship with depth while varying the exposure amount. Patent applicant Tokyo Ohka Kogyo Co., Ltd.

Claims (1)

[Scope of Claims] 1. A developer comprising an organic alkaline aqueous solution for positive resists containing an alkali-soluble novolac resin and a naphthoquinone diazide compound, characterized in that an alkali-soluble cyclic nitrogen compound is added to the organic alkaline aqueous solution. A developer for positive resists. 2. The developer according to claim 1, wherein the organic alkaline aqueous solution is an aqueous solution containing at least one selected from tetramethylammonium hydroxide and choline. 3 The alkali-soluble cyclic nitrogen compounds include N-hydroxyethylpiperazine, N-methyl-4-piperidone and 1,
The developing solution according to claim 1 or 2, wherein the developer is at least one selected from 3-dimethyl-2-imidazolidinone. 4 The alkali-soluble nitrogen compound is 1,3-dimethyl-2
- The developer according to claim 3, which is an imidazolidinone.