JP2877657B2 - Step coverage positive resist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a novel positive resist composition, and more particularly, to a step having excellent coating properties, storage stability and safety which are preferably used in the production of materials for electronic parts. The present invention relates to a positive resist composition having coverage.

[0002]

2. Description of the Related Art In the production of electronic component materials such as semiconductor elements and liquid crystal display elements, a pattern transfer method using photolithography is used as a method for forming a pattern on a substrate. In this photolithography, a resist is applied to a substrate such as a silicon wafer using a spinner, dried, then irradiated with actinic rays through a mask, developed, and the mask pattern is transferred onto the substrate, and then etched. It is. The resist used as the mask for this etching was initially a negative type resist. However, the negative type resist is currently used for the resolution limit due to expansion in a developing solution and the problem of mask damage in contact exposure. Positive resists having excellent image properties are often used.

[0003] In recent years, silicon wafers and glass substrates have been increasing in size. In applying a resist on the substrate, it is desired that the coating film has excellent uniformity. When forming a coating film, the smaller the difference between the film thickness of the coating film formed on the concave portion and the film thickness of the coating film formed on the convex portion, the more the resist pattern with excellent resolution is formed. Therefore, it is required that the film thickness difference between coating films is small, that is, excellent in step coverage, and the influence of chemicals on the environment and human body is a major problem. There is a strong demand for a resist that does not harm the resist, and various studies have been made on a solvent for the resist.

Hitherto, many solvents have been known as solvents for positive resists, such as ethylene glycol monoethyl ether acetate, cyclopentanone (JP-A-59-155838), and monooxymonocarboxylic acid esters. (JP-A-62-123444), a mixed solvent of a cyclic ketone and an alcohol (US Pat. No. 452).
No. 6856) and propylene glycol alkyl ether (Japanese Patent Application Laid-Open No. 61-7837). However, none of these solvents has poor uniformity and coating properties and has no step coverage. .

[0005]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional positive resist composition using a solvent and provides a step having excellent coating properties, storage stability and safety. The object of the present invention is to provide a positive resist composition having coverage.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to develop a positive resist composition having step coverage, and as a result, have found that an alkali-soluble resin and a quinonediazide group-containing compound can be combined with a specific compound. Have been found to achieve the object when dissolved in an organic solvent obtained by mixing at a predetermined ratio, and the present invention has been completed based on this finding.

That is, the present invention provides (A) an alkali-soluble resin and (B) a quinonediazide group-containing compound,
(C) (A) ethyl 2-oxypropionate 60 to 90
% By weight and (b) 40 to 10% by weight of butyl acetate or (a)
60 to 90% by weight of ethyl 2-oxypropionate, 30 to 5% by weight of (ii) butyl acetate and (C) xylene 10
It is intended to provide a step-coverable positive resist composition which is dissolved in a mixed solvent of up to 5% by weight.

In the composition of the present invention, examples of the alkali-soluble resin used as the component (A) include a novolak resin, an acrylic resin, a copolymer of styrene and acrylic acid, a polymer of hydroxystyrene, polyvinylphenol, and polyα. -Methylvinylphenol and the like, and among them, an alkali-soluble novolak resin is particularly preferable. The alkali-soluble novolak resin is not particularly limited, and those conventionally used as a film-forming substance in a positive photoresist composition, for example, phenols, cresols, aromatic hydroxy compounds such as xylenol and aldehydes such as formaldehyde can be used. Those condensed in the presence of an acidic catalyst are used. The alkali-soluble novolak resin has a weight average molecular weight of 2,000 to 20,000 obtained by cutting a low molecular weight region,
Preferably, those in the range of 5000 to 15000 are suitable.

In the composition of the present invention, a quinonediazide group-containing compound is used as the photosensitive component of the component (B). As the quinonediazide group-containing compound, for example, orthobenzoquinonediazide, orthonaphthoquinonediazide, sulfonic acid of quinonediazides such as orthoanthraquinonediazide, and partial or complete esterification of a compound having a phenolic hydroxyl group or an amino group,
Alternatively, a partially or completely amidated product may be used. Examples of the compound having a phenolic hydroxyl group or an amino group include 2,3,4-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, and 2,3,4,4'-tetrahydroxybenzophenone. Polyhydroxybenzophenone, alkyl gallate, aryl gallate, phenol, phenolic resin, p-methoxyphenol, dimethylphenol, hydroquinone, polyhydroxydiphenylalkane, polyhydroxydiphenylalkene, bisphenol A, α, α ′, α ″ -tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, 1-
[1- (4-hydroxydiphenyl) isopropyl]-
4- [1,1-bis (4-hydroxydiphenyl) ethyl] benzene, tris (hydroxyphenyl) methane or its methyl-substituted product, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol 1,3-dimethyl ether, gallic acid Gallic acid esterified or etherified leaving a part of hydroxyl groups,
Examples include aniline and p-aminodiphenylamine. Particularly preferred quinonediazide group-containing compound is a fully esterified product or a partially esterified product of polyhydroxybenzophenone and naphthoquinone-1,2-diazido-5-sulfonic acid or naphthoquinone-1,2-diazide-4-sulfonic acid, particularly The average degree of esterification is 70 mol%
The above are preferred.

In the composition of the present invention, the aforementioned quinonediazide group-containing compound may be contained alone or in combination of two or more as the photosensitive component.

The quinonediazide group-containing compound may be prepared, for example, by converting the above-mentioned polyhydroxybenzophenone into naphthoquinone-1,2-diazido-5-sulfonyl chloride or naphthoquinone-1,2-diazide-4-sulfonyl chloride in a suitable solvent such as dioxane. It can be produced by condensing in the presence of an alkali such as triethanolamine, an alkali carbonate or an alkali hydrogen carbonate, followed by complete esterification or partial esterification.

In the composition of the present invention, as the organic solvent used as the component (C), a mixed solvent of (a) ethyl 2-hydroxypropionate and (b) butyl acetate is used.

The butyl acetate of the component (ii) may be either n-butyl acetate or isobutyl acetate, but butyl acetate is particularly preferred. Further, these organic solvents may be used alone or in combination of two or more.

This butyl acetate has the function of adjusting the viscosity of the positive resist solution, and can improve the uniformity of the applied film thickness when applied on a substrate.

In the present invention, the mixed solvent of the component (a) and the component (b) may further include (c)
Xylene can be blended as a component. As a result, the solubility of the alkali-soluble resin and the quinonediazide group-containing compound can be improved, and a positive resist composition having good storage stability can be prepared.

With respect to the content ratio of each component in the mixed organic solvent used as the component (C) in the composition of the present invention, when the two components of the component (a) and the component (b) are contained, the component (a) 60 to 90% by weight and (b) component 40
And 10% by weight, and when component (a), component (b) and component (c) are contained, component (a) 6
0 to 90% by weight, (B) component 30 to 5% by weight, and (C)
The proportion of the component is 10 to 5% by weight. If the content ratio of each component is out of the above range, it is impossible to obtain a step-coverable positive resist composition having improved coating properties, storage stability and safety, which is the object of the present invention.

The composition of the present invention may further comprise, if necessary, a compatible additive such as an additional resin, a plasticizer, a stabilizer for improving the performance of the resist film, or a pattern obtained by development. It is possible to add and blend a commonly used colorant such as a colorant for further visualizing, a sensitizer for further improving the sensitizing effect, and a contrast improver.

The composition of the present invention is prepared by adding
It is advantageous to dissolve the alkali-soluble resin, the quinonediazide group-containing compound and the optional components to be added as required in the required amounts, and use them in the form of a solution.

Regarding the preferred method of using the composition of the present invention,
For example, first, on a substrate such as a silicon wafer,
A solution obtained by dissolving the alkali-soluble resin and the quinonediazide group-containing compound in the above-mentioned mixed organic solvent is applied by a spinner, a roll coater, or the like, dried to form a photosensitive layer, and then a light source that emits ultraviolet light, for example, a low-pressure light source. Using a mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, arc lamp, xenon lamp, etc., exposure through a required mask pattern, exposure using a reduction projection exposure apparatus, or irradiation with an excimer laser or X-ray through the mask pattern Alternatively, irradiation is performed while scanning an electron beam. Next, when this is immersed in a developing solution, for example, an alkaline aqueous solution such as an aqueous solution of 1 to 10% by weight of tetramethylammonium hydroxide, a portion solubilized by exposure is selectively dissolved and removed, and an image faithful to the mask pattern is formed. Can be obtained.

Such a pattern is not limited to semiconductor processing, but is used in the field of processing using lithography, for example, LC.
D, TAB, PCB, chemical milling, printing, and the like also provide excellent effects. In particular, the composition of the present invention is a practical solution in which a coating film excellent in uniformity could not be obtained with a conventional organic solvent, and in coating on a large substrate or a square substrate, an extremely high coating film can be easily obtained. It works.

[0021]

The positive resist composition of the present invention is characterized in that it uses a mixed solvent of ethyl 2-oxypropionate, butyl acetate and optionally xylene as a solvent for preparing the positive resist composition, thereby improving the coating properties and preservation. It can form a coating film with excellent step coverage with excellent stability,
Further, the prepared solvent does not adversely affect the environment or the human body, and is therefore extremely effective in practical use.

[0022]

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

The physical properties in each example were obtained by the following methods. (1) Uniformity A coating solution of a positive resist composition was applied on a 6-inch silicon wafer at 3000 rpm for 20 seconds, and the coating was performed at 90 ° C. for 9 seconds.
A coating film is formed by drying on a hot plate for 0 second, and the thickness of the coating film is measured over the entire surface of the wafer. If the variation in the film thickness on the wafer is ± 20 ° or less, ○, ± 21 to Those of 40 ° were evaluated as Δ, and those of ± 41 ° or more were evaluated as x.

(2) Storage Stability The coating solution of the prepared positive resist composition was prepared to be 0.2 μm
And then allowed to stand at 40 ° C. for 3 months to observe the presence or absence of precipitates in the solution. Those without precipitates were evaluated as no, and those with precipitates were evaluated as present.

(3) Step Coverage A coating solution of the positive resist composition is applied on a 6-inch silicon wafer on which a 0.5 μm-thick silicon oxide film pattern is formed in a 2.0 μm-wide line and space.
The coated film is formed on the entire surface of the wafer by coating with a spinner so that the dry film thickness on a flat surface without a silicon oxide film pattern is 1.5 μm, and then dried. The difference between the film thickness and the film thickness of the coating film formed on the space was measured, and the difference was 0.10.
μm or less: ○, 0.11 to 0.20: Δ,
Those having a size of 0.21 μm or more were evaluated as x.

Example 1 2,3,4,4'-Tetrahydroxybenzophenone 1
Of cresol novolak resin in a mixed solvent of 40 g of ethyl 2-oxypropionate and 10 g of butyl acetate. Thus, a coating solution of a positive resist composition was prepared. The physical properties of this coating solution were examined, and the results are shown in Table 1.

Examples 2 to 7 and Comparative Examples 1 and 2 Coating solutions of the positive resist composition were prepared in the same manner as in Example 1 except that the mixed solvents shown in Table 1 were used.
The physical properties of this coating solution were examined, and the results are shown in Table 1.

[0028]

[Table 1]

Example 8 40 g of ethyl 2-oxypropionate and 5 g of butyl acetate
A coating solution of a positive resist composition was prepared in the same manner as in Example 1, except that a mixed solvent consisting of benzene and 5 g of xylene was used. The physical properties of this coating solution were examined and evaluated. As a result, the uniformity was good, the storage stability was no, and the step coverage was good.

Continuation of front page (72) Inventor Toshimasa Nakayama 150 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Tokyo Ohka Kogyo Co., Ltd. (56) References JP-A-3-107165 (JP, A) JP-A-62-36657 ( JP, A) JP-A-1-293340 (JP, A) JP-A-3-185448 (JP, A) JP-A-3-130774 (JP, A) JP-A-3-125152 (JP, A) JP JP-A-5-273750 (JP, A) JP-A-6-167811 (JP, A) JP-A-6-118650 (JP, A) JP-A-6-118649 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G03F 7/022 G03F 7/004

Claims (2)

(57) [Claims] 1. An alkali-soluble resin (A) and a quinonediazide group-containing compound (B) are mixed with (C) (A) 60-90% by weight of ethyl 2-oxypropionate and (B) 40-10% by weight of butyl acetate. %, Wherein the resist composition is dissolved in a mixed solvent comprising: (A) an alkali-soluble resin, and (B)
The quinonediazide group-containing compound is compounded with (C) (a) 60-90% by weight of ethyl 2-oxypropionate, (b) 30-5% by weight of butyl acetate, and (C) 10-5% by weight of xylene.
A step-coverable positive resist composition dissolved in a mixed solvent comprising: