JPH0534903A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To improve storage stability and to enhance resolution by incorporating an alkali-soluble resin, an acid-photogenerator, a cross-linking agent, and a specified coating solvent. CONSTITUTION:The photosensitive composition comprises the alkali-soluble resin, the acid-photogenerator, the cross-linking agent of this resin to be activated in an acid condition, and the solvent, represented by formula I in which each of R<1> and R<2> is, independently, acetyl or 1-4 C alkvl; and m is 1 or 2. The alkali-soluble resin is, preferably, such as polyvinvl phenol derivative having a novolak resin obtained by polycondensing aromatic hydroxyl compound, such as phenol or cresol, with formaldehyde or the like, and an organic halogen compounds are enumerated as the acid-photogenerator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a negative photosensitive composition which is sensitive to radiation, and more specifically to a negative photosensitive composition which is suitable for producing a semiconductor integrated circuit and has excellent storage stability. It relates to a photoresist solution.

[0002]

2. Description of the Related Art Conventionally, a positive resist made of an alkali-soluble novolak resin and a naphthoquinonediazide compound has been generally used as a photoresist for producing a semiconductor integrated circuit. However, as the degree of integration increases, it is necessary to shorten the exposure wavelength or to improve the exposure method by a phase shift method or the like in order to meet the demand for high resolution of 0.3 μm level. Photoresists containing positive quinonediazide compounds, which have large absorption in the short wavelength region, have become unusable. Further, in the phase shift method, a negative type resist is desired because it is advantageously used in the negative type because of its advantage.

Under such circumstances, a resist composition having the above performance is disclosed in JP-A-62-164045 and JP-A-2-
No. 15270 and JP-A-1-293339 disclose that
A negative photoresist containing an alkali-soluble resin, a photoacid generator, and a crosslinking agent that acts under acidic conditions has been proposed. The applicant of the present invention also applied for a patent for such a negative photoresist (Japanese Patent Application No. 2-260156).
Etc.).

However, these so-called chemically amplified resists have a drawback that they are inferior in storage stability in a composition (liquid) as compared with quinonediazide resists. That is, when the resist solution is stored at 25 ° C., the sensitivity may deteriorate by 20% or more within one year. Further, among known solvents for photoresists, there are some problems such as methyl cellosolve acetate which are not practically preferable because of their toxicity.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed a negative photoresist containing an alkali-soluble resin, a photo-acid generator, a cross-linking agent and a solvent, which has good storage stability. As a result of repeated studies to provide the same, it was found that the storage stability of the resist solution has a significant correlation with the pKa of the solvent, and the resist solution having a pKa of the solvent at room temperature of 22 or more has good storage stability. However, some solvents having a pKa of 22 or more are problematic in terms of toxicity, and as a result of further investigation, a resist composition containing a specific solvent has good storage stability and also has a problem of toxicity. The inventors have found that there is nothing and have reached the present invention.

[0006]

The summary of the present invention is as follows.
A negative photosensitive composition comprising an alkali-soluble resin, a photo-acid generator, a cross-linking agent for the alkali-soluble resin that acts under acidic conditions, and a compound represented by the above formula [I] as a solvent. The present invention will be described in detail below.

The alkali-soluble resin used in the present invention is not particularly limited, but those having a phenolic hydroxyl group are preferable. Examples of such resins include phenol, cresol, ethylphenol, t-butylphenol, xylenol, naphthol, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene and other hydroxy aromatic compounds such as formaldehyde, acetaldehyde, benzaldehyde, furfural and the like. Novolak resin polycondensed with aldehyde, polyvinylphenol derivative which may have a substituent such as lower alkyl group, N
Examples thereof include-(p-hydroxyphenyl) maleimide polymer. Of these, polyvinylphenol derivatives or condensation polymers of cresol and formaldehyde are preferable.

The photo-acid generator used in the present invention is from 150 to
A photoacid generator that generates an acid with light in the range of 400 nm is desirable, and examples thereof include an organic halogen compound, an onium salt, and a sulfonate ester. For example, Polymeric Materials Science and Engineering No. 61
Vol. 63, American Chemical Society, J.
V. Examples thereof include onium salts and sulfonates disclosed by Klibero, and photosensitive organic halogen compounds disclosed in Japanese Patent Publication No. 54-23574.

Specifically, carbon tetrabromide, iodoform,
1,2,3,4-tetrabromobutane, 1,1,2,2
-Halogen-substituted alkanes such as tetrabromoethane;
Halogen-substituted cycloalkanes such as hexabromocyclohexane, hexachlorocyclohexane, hexabromocyclododecane; tris (trichloromethyl) -s-
Triazine, tris (tribromomethyl) -s-triazine, tris (dibromomethyl) -s-triazine,
Halogen-containing s-triazine derivatives such as 2,4-bis (tribromomethyl) -6-p-methoxyphenyl-s-triazine; Halogen-containing benzene derivatives such as bis (dibromomethyl) benzene and bis (tribromomethyl) benzene A halogen-containing sulfone compound such as tribromomethylphenyl sulfone, trichloromethylphenyl sulfone and 2,3-dibromosulfolane; an onium salt such as diphenyliodonium triflate and diphenyliodonium tosylate.

Among them, an organic halogen compound is preferable, an organic halogen compound containing a bromine atom or an iodine atom is preferable, and a bromine atom-containing organic halogen compound is particularly preferable, from the viewpoint of resolution and storage stability of the resist composition. is there. Examples of the cross-linking agent for an alkali-soluble resin that acts under acidic conditions include compounds described in JP-A-59-113435, JP-A-60-263143, and JP-A-62-164045, and A. knop, L .; A.
The compounds described in Phenolic Resins by Pilato and the like can be mentioned.
A compound having two or more groups represented by in the molecule is preferably used.

Specific examples of the cross-linking agent include compounds represented by the following formulas [III] to [VI].

[0012]

[Chemical 1]

[0013]

[Chemical 2]

[0014]

[Chemical 3]

[0015]

[Chemical 4]

In the above formulas [III] to [VI], Q ¹
To Q ¹¹ each independently represent a hydrogen atom or an alkyl group, and
Represents an optionally substituted alkyl group, an alkenyl group, an aryl group or a 5- or 6-membered aromatic heterocyclic group, B represents a hydrogen atom or —CH ₂ OQ ¹² , and Q ¹² represents an alkyl group, U represents a divalent organic group, D _{1 to} D ₄ each independently represent a hydrogen atom or —CH ₂ OQ ¹³ , and Q 1
¹³ represents an alkyl group, and n represents 0 or 1. However, at least two of D _{1 to} D ₄ are not hydrogen atoms. Among them, in the formulas [III] to [VI], Q ^{1 to} Q ¹³ are C ₁
~C alkyl group having ₄ compounds are preferable.

The proportion of the alkali-soluble resin, the photo-acid generator and the cross-linking agent in the photosensitive composition of the present invention is usually 0.05 with respect to 100 parts by weight of the alkali-soluble resin.
To 20 parts by weight, preferably 0.1 to 10 parts by weight, and the crosslinking agent is 1 to 50 parts by weight with respect to 100 parts by weight of the alkali-soluble resin.
It is used in a proportion of parts by weight, preferably 5 to 30 parts by weight.

In the present invention, the above-mentioned alkali-soluble resin,
It is characterized in that the compound represented by the above formula [I] is used as a solvent for a negative photosensitive composition containing a photoacid generator and a crosslinking agent. The compound represented by the above formula [I] has a pKa (−log ₁₀ Ka, Ka: ionization constant) at room temperature.
However, according to the study by the present inventors, in a negative resist containing a photo-acid generator and a cross-linking agent, a solvent having a pKa of 22 or more and a solvent having a pKa of less than this have storage stability. It is completely different, and the latter solvent causes a marked deterioration in sensitivity and is practically unusable. On the other hand, among the solvents having a pKa of 22 or more, there is a problem in storage stability but a problem in coating property, and there is a solvent in which striation occurs.

Methyl cellosolve acetate, which is known as a solvent for photoresist compositions, has a pKa of 22 or more, but has a problem of toxicity and is not preferable in practice. The photoresist composition containing the solvent represented by the above formula [I] has little deterioration in sensitivity when stored at room temperature and has little deterioration in sensitivity even in an accelerated deterioration test at high temperature, and has extremely excellent storage stability. Is good. In addition, the coatability to the substrate is good and there is no problem of toxicity.

In the above formula [I], the C ₁ -C ₄ alkyl group represented by R ¹ and R ² includes a methyl group, an ethyl group, an n-propyl group, an i-propyl group and an n-group. Examples thereof include linear or branched alkyl groups such as a butyl group and a sec-butyl group. Specific examples of particularly suitable solvents include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and dipropylene glycol dimethyl ether.

The proportion of the solvent used is in the range of 1 to 20 times as a weight ratio with respect to the total amount of solids in the photosensitive composition. The negative photosensitive composition of the present invention may optionally contain additives such as a surfactant, a coating property improver, a stabilizer, a dye, and a UV absorber, as long as the performance thereof is not changed. .

The negative photosensitive composition of the present invention is used as a photoresist through the following steps of coating, exposure, post-exposure baking (PEB) and development as described below. A spin coater is usually used for coating, and a suitable film thickness is about 0.5 μm to 2 μm.

For the exposure, light in the deep UV region, for example, 254 nm light using a low pressure mercury lamp as a light source, or 157 nm, 193 nm, 22 using an excimer laser or the like as a light source.
Light of 2 nm and 249 nm is preferably used. Further, it can be applied to light of 366 nm and 436 nm of a high pressure mercury lamp. Light at the time of exposure may be broad instead of monochromatic light. It is also suitable as a resist for the phase shift method. The post-exposure heating (PEB) is performed using a hot plate, and the conditions of 90 to 140 ° C. and 1 minute to 10 minutes are preferably used. A convention oven may be used instead of the hot plate. This usually requires a longer time than using a hot plate.

The developing solution contains potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, inorganic alkalis such as aqueous ammonia, ethylamine,
Primary amines such as n-propylamine, secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine and trimethylamine, tetramethylammonium hydroxide, trimethylhydroxyethylammonium hydro An alkaline developer comprising an aqueous solution of a quaternary ammonium salt such as cyside is preferably used. If necessary, alcohol or a surfactant may be added to the developer for use.

The photoresist solution and the developing solution are filtered before use to remove insolubles. The negative photosensitive composition of the present invention is not only for the production of VLSI,
General IC manufacturing, further mask manufacturing, flat plate, intaglio, letterpress, photoresist for print wiring, solder resist, image formation such as relief image and image duplication, photocurable ink, paint It can be used for adhesives, etc.

[0026]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the examples as long as the gist thereof is not exceeded. Examples 1 to 8 and Comparative Examples 1 to 9 20 g of the alkali-soluble resin shown in Table 1, a photo-acid generator of the type and amount shown in Table 1, and a cross-linking agent 4 g shown in Table 1 as a solvent shown in Table 1. It was dissolved in 70 g and microfiltered using 0.2 μm filter paper made of Teflon to prepare a photoresist composition. This photoresist composition was spin-coated on a silicon wafer having a diameter of 4 inches (1H manufactured by Mikasa).
-2D) to a thickness of 1.0 micron and dried on a hot plate at 100 ° C. for 70 seconds. This was exposed with a KrF excimer laser reduction projection exposure apparatus while changing the exposure amount, and then exposed on a hot plate.
Heated at 0 ° C. for 90 seconds (PEB). 1.23% thereafter
A negative image was formed by developing with a tetramethylammonium hydroxide aqueous solution for 70 seconds. The obtained resist pattern was observed with a scanning electron microscope (manufactured by Akashi Seisakusho), and the resolution is shown in Table 1.

On the other hand, a photoresist composition prepared in the same manner was divided into 1 and 1 week at 43 ° C. and 5 ° C., respectively.
Stored for a week. The photoresist composition after storage was applied on a silicon wafer to a thickness of 1.0 μm, and the presence or absence of striation was visually determined. Further, this was dried on a hot plate at 100 ° C. for 70 seconds and then placed under a 6 W low-pressure mercury lamp (manufactured by Ushio Inc.) at a position of 20 cm, and the light of 254 nm was irradiated while changing the time. At this time, the light intensity on the resist film surface was 0.40 mW / cm ² . Then, heat on a hot plate at 110 ° C for 90 seconds (PEB)
After that, the resist film was developed with a 1.23 wt% tetramethylammonium hydroxide aqueous solution and the dissolution rate of the resist film was measured.

A graph showing the relationship between the resist film dissolution rate and the exposure energy was prepared for each photoresist composition before and after storage, and the exposure dose (mJ / cm ²⁾ giving a dissolution rate of 10Å / sec was drawn from each graph. ) Is read, this is defined as sensitivity, and a result is shown in Table 1. Table 1 also shows a value (sensitivity ratio) obtained by dividing the sensitivity after storage at 43 ° C for 1 week by the sensitivity after storage at 5 ° C for 1 week.

The abbreviations in Table 1 have the following meanings. PVP: Polyvinylphenol (weight average molecular weight 51
00) NV: m-cresol / p-cresol = 7/3
Novolac resin (weight average molecular weight 5100) TBB: 1,2,3,4-tetrabromobutane HBCH: 1,2,3,4,5,6-hexabromocyclohexane TBPS: tribromomethylphenyl sulfone DBS: 2,3 -Dibromosulfolane BICN: Tris (2,3-dibromopropyl) isocyanurate C300: Hexamethoxymethylmelamine (Cymel)
Trademark registration 300, manufactured by Mitsui Cyanamid Co., Ltd.) MMSA: N, N'-dimethoxymethylsuccinamide

[0030]

[Table 1]

Example 9 and Comparative Example 10 The resist solutions of Example 1 and Comparative Example 6 were evaluated in the same manner as in Example 1 except that the storage conditions were 5 ° C. for 1 week and 25 ° C. for 2 months. The sensitivity of the resist solution of Example 1 (m
J / cm ² ) was 7.0 after storage at 5 ° C. for 1 week and 7.0 at 25 ° C. for 3 months, and the sensitivity ratio was 1.00, which was a good value (Example 9). On the other hand, the sensitivity of the resist solution of Comparative Example 6 (m
J / cm ² ) was stored at 5 ° C for 1 week at 8.7, 25 ° C 3
The storage ratio for months was 11.3, which was inferior to the sensitivity ratio of 1.30. (Comparative Example 10)

[0032]

The photoresist composition of the present invention contains the compound of the above formula [I] as a coating solvent.
It has no problem of toxicity, has very good storage stability, and has good resolution, which is extremely useful in practice.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area H01L 21/027

Claims (3)

[Claims] 1. A negative photosensitive resin containing an alkali-soluble resin, a photo-acid generator, a cross-linking agent for an alkali-soluble resin that acts under acidic conditions, and a compound represented by the following formula [I] as a solvent. Composition. R ¹ - [OCH (CH ₃₎ CH _{2] m} -OR ² · · · · [I] (wherein, R ¹ and R ² are acetyl groups or C each independently
₁ -C ₄ represents an alkyl group, m represents 1 or 2. ) 2. The composition according to claim 1, wherein the photo-acid generator is an organic halogen compound containing a bromine atom or an iodine atom. 3. The composition according to claim 1, wherein the crosslinking agent is a compound having two or more groups represented by the formula [II] in the molecule. -N (CH ₂ OQ) - ···· [II] (wherein, Q is an alkyl group of C ₁ ~C _4.)