JPH05188596A - Resist composition - Google Patents

Abstract

PURPOSE:To obtain the resist compsn. having high sensitivity with photoirradiation. CONSTITUTION:The resist compsn. consisting of (a) a polymer contg. (meth) acrylate contg. the group selected from a group consisting of a t-butyl group, benzyl group, methyl benzyl group, alpha,alpha'-dimethyl benzyl group and tolytyl group as an essential monomer component without contg. a cyano group and (b) a photoactivator which generates an acid when exposed to radiations is provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resist material comprising a polymer having a highly regulated terminal molecular structure and a photoactivator which produces an acid when exposed to radiation. More specifically, the present invention relates to a novel resist composition having particularly excellent sensitivity, which is useful for printing plates, photoresists for integrated circuits, photoresist materials for color filters and the like.

[0002]

2. Description of the Related Art There are two types of resist compositions, a negative type (a part exposed to light is cured) and a positive type (a part exposed to light is eluted with a developing solution). The positive type has a higher resolution than the negative type and is widely used for lithographic printing and resists for integrated circuits. Japanese Patent Publication No. 02-27660 discloses a resist composition containing a compound which produces an acid upon irradiation and a polymer which produces a phenol group or a carboxylic acid group by the acid.

[0003]

However, since the compositions described in the above publications do not have sufficient sensitivity for applications such as printing, resists for color filters, resists for integrated circuits, etc., the exposure time There is a problem that it becomes long and work efficiency is poor. An object of the present invention is to provide a new resist composition having higher sensitivity to light irradiation.

[0004]

In order to achieve the above-mentioned object, an acid-labile branched group described in the above publication is used.
As a result of rigorous analysis of the polymer of (meth) acrylic acid ester, it is a radical polymerization initiator segment contained in the polymer. It has been found that the terminal unsaturated bond produced by the disproportionation termination reaction with the nitrile group has an inhibitory action in the reaction of producing a carboxylic acid with an acid, and the inhibitory action by the nitrile group is particularly remarkable. Based on this result, the acid-labile branched (meth) acrylic acid ester was prepared using a radical polymerization method using an initiator that does not contain a nitrile group or a living anion polymerization method that does not generate a nitrile group or a terminal unsaturated bond. , Homopolymerization, or other α, β-
Upon copolymerization with an ethylenically unsaturated compound, it was found that the sensitivity of a resist composition using the obtained polymer was dramatically improved, and the present invention was accomplished.

That is, the present invention relates to (meth) acrylic having (a) a group selected from the group consisting of t-butyl group, benzyl group, α-methylbenzyl group, α, α'-dimethylbenzyl group and trityl group. Acid ester as an essential monomer component,
Also provided is a resist composition comprising a cyano group-free polymer and (b) a photoactivator that produces an acid when exposed to radiation.

A method for preparing a polymer (a) not containing a nitrile group and a polymer not containing a nitrile group and a terminal unsaturated bond (this is particularly referred to as a polymer (c)) to be blended in the resist composition of the present invention. The known radical polymerization method and living anion polymerization method are suitable as the polymer.
The living anion polymerization method is most suitable as the method for preparing (c). That is, the (meth) acrylic acid monomer as an essential monomer component when preparing the polymer (a) or (c), if necessary, in the presence of other copolymerizable α, β-ethylenically unsaturated monomer, The polymer (a) or (c) can be obtained by homopolymerization or copolymerization.

The (meth) acrylic acid ester monomer for preparing the polymer (a) or (c) is a t-butyl group, a benzyl group, an α-methylbenzyl group, an α, α-dimethylbenzyl group, and a trityl group. And so on. Specific examples of such a monomer include tert-butyl (meth) acrylate,
In addition, benzyl (meth) acrylate, α-methylbenzyl (meth) acrylate, α, α-dimethylbenzyl (meth) acrylate, trimethy (meth) acrylate and other (meth) acrylic acid benzhydryl esters can be mentioned.

The polymer (a) or (c) incorporated into the composition of the present invention may be a homopolymer or a copolymer. Therefore,
The above (meth) acrylic acid ester monomers may be used alone or in combination, and may be copolymerized with other copolymerizable α, β-ethylenically unsaturated monomers.

The other copolymerizable α, β-ethylenically unsaturated monomer is not particularly limited, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, propyl (meth). Acrylate,
Isopropyl (meth) acrylate, phenyl (meth) acrylate and other (meth) acrylic acid esters, styrene,
p- (m-) methylstyrene, α-methylstyrene, p- (m
Examples thereof include styrene derivatives such as-) chlorostyrene and p- (m-) bromostyrene. One or more of these may be used. Although the amount used is not particularly limited, for example, 0 to 30 wt% of the essential monomer is preferable.

When the polymer is prepared by the radical polymerization method, it can be carried out by any method such as solution polymerization, suspension polymerization and emulsion polymerization according to a known method using a radical polymerization initiator containing no nitrile group. is there.

When the polymer is prepared by the living anionic polymerization method, the anionic polymerization initiator is used to carry out the polymerization reaction. The polymerization initiator is not particularly limited as long as it can be used for anionic polymerization, and, for example, an organic alkali metal compound and an organic magnesium halide can be used. Specific examples of the organic alkali metal compound include, for example, n-butyllithium and sec-
Butyl lithium, tert-butyl lithium, 1,1-diphenylhexyl lithium, fluorenyl lithium, cumyl potassium, cumyl cesium and the like can be mentioned. Specific examples of the organomagnesium halide include sec-
Butyl magnesium chloride, tert-butyl magnesium chloride, benzyl magnesium chloride, se
C-butyl magnesium bromide, tert-butyl chloride bromide, benzyl magnesium bromide and the like can be mentioned, and one or more of them may be used. The amount used is uniquely determined by the molecular weight of the polymer to be produced.

The polymerization reaction is carried out at approximately -80 ° C to 100 ° C.
In general, the above components are stirred and mixed in an inert gas atmosphere or under reduced pressure (preferably under high vacuum) in a solvent inert to the polymerization reaction. Specific examples of the solvent that can be used include aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, ethers such as tetrahydrofuran, 1,4-dioxane and diethyl ether, and cyclohexane. Further, two or more kinds of solvents can be mixed and used. The polymerization concentration is not particularly limited, but it is preferably carried out within the range of 1 to 20 wt%. Furthermore, the polymerization reaction time varies depending on the type of the monomer used, the polymerization and the polymerization temperature, but is generally 1 minute to 72 hours, for example.

During the polymerization reaction, tertiary amines such as tetramethylethylenediamine, dipiperidinoethane, triethylamine and N-methylpyrrolidone 12-crown-4,15-
One or more kinds of crown ethers such as crown-5 and salts having the same ion as the counter cation at the growth end, such as lithium chloride, sodium chloride, potassium chloride, and cesium chloride can be used. The addition amount of these is not particularly limited, but it is general to add 1 to 10 times mol to the growth end. After polymerizing the monomer, the living end can be contacted with a proton donor or an alkylsilyl halide to deactivate it. Specific examples of the proton donor include alcohols such as methanol, ethanol and phenol, and water. Examples of alkylsilyl halides include trimethylsilyl chloride and the like. One or more of these may be used.

The number average molecular weight of the obtained polymers (a) and (c) is 1,000 to 1,000,000, and particularly 10,000 to.
200,000 is preferred. When the number average molecular weight is out of this range, not only it becomes difficult to control the polymerization temperature and to purify the monomer and solvent, but also sufficient film properties cannot be obtained when the film is formed, and the solubility in an alkaline solution decreases. It causes problems and is not preferable.

The resist composition of the present invention contains the above polymer
In addition to (a) or (c), a photoactivator (b) is further contained. The photoactivator (b) produces a strong acid against light irradiation, which attacks and decomposes the branched pendant group that is unstable to acid to produce a carboxyl group, a phenolic acid group, etc. It enables development. As such a photoactivator (b) which generates an acid upon irradiation with light, an onium salt is generally known in the past. Representative examples of the photoactivator (b) include diaryl iodonium salts, triaryl sulfonium salts, triaryl selenium salts and the like, and one or more kinds can be used. Suitable counter anions include tetrafluoroborate, trifluoromethanesulfonate, hexafluoroantimonate, hexafluoroarsenate and complex metal halide compounds such as hexafluorophosphate. The resist composition of the present invention may further contain a photosensitizer in order to make it sensitive to light having a longer wavelength from ultraviolet rays to visible rays. Any known photosensitizer can be used. It may be a polycyclic aromatic, such as pyrene and perylene. Other dyes such as acridine may also be used. One or more of these may be used.

In the composition of the resist composition of the present invention, the photoactivator (b) is used in an amount of 0.1 to 50 w relative to the polymer (a) or (c).
t%, especially 1 to 30 wt%, photosensitizer (when compounded)
0.01 to 10% by weight, particularly 0.1 to 5% by weight is preferable.
If the amount of the photoactivator (b) exceeds 50% by weight, sufficient film strength cannot be obtained and it is economically unsuitable. The preparation of the resist composition of the present invention is carried out by mixing the polymer (a) or (c), the photoactivator (b) which produces an acid, and the sensitizer, if necessary, or in a solvent in a cool and dark place if necessary. Is preferred. Solvents that can be used include ketones (for example, acetone, methyl ethyl ketone, cyclohexanone, etc.): Esters (for example, ethyl acetate, butyl acetate, ethylene glycol acetates); Ethers (for example, tetrahydrofuran, dioxane, etc.), and these One or more of can be used.

The resist composition of the present invention is first coated on a support, dried, exposed to light using a positive film, and then developed. Examples of the support include a steel plate, a treated glass plate and a silicon wafer. The coating is carried out by a usual method such as spin coating, wire bar coating, dip coating or roll coating. Light sources for light irradiation include light sources such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a xenon lamp, and a low pressure mercury lamp. In the present invention, a dose of 30 mJ / cm ² is generally sufficient. For the development, an alkaline developer such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium metasilicate, potassium metasilicate or the like can be used. The concentration of this developer is preferably used in the range of 0.1 to 10% by weight.

[0018]

Since the resist composition of the present invention has very high sensitivity, it can be easily developed with a small amount of light, and is suitably used for various applications such as printing, color filters and integrated circuits.

[0019]

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

Preparation Example 1 The polymerization reaction was carried out under high vacuum using the breakable seal method. First, tetrahydrofuran of sodium salt of α-methylstyrene tetramer
The (THF) solution was put into a polymerization container, and the inside of the container was thoroughly washed and then removed. Then, at room temperature, with THF (198 ml), 1,1
-Diphenylhexyllithium benzene solution (3.0 m
mol, 18 ml) and the container was cooled to -78 ° C. Next, tert-butyl methacrylate (123 mmol) in THF
A solution (111 ml) was added to start the polymerization reaction. After stirring for 2 hours, methanol (2 ml) was added to stop the polymerization reaction. This reaction solution was mixed with a large amount of methanol / water mixed solution (6
7/33 vol%) to precipitate the product. The product was dried, purified by reprecipitation with an acetone-methanol-water mixed solvent system, and then freeze-dried. The resulting polymer 18.
2 g (100% yield) Mu (GPC) (number average molecular weight measured by GPC) = 0.58 × 10 ³ , Mw / Mn = 1.57,
Tg = 61 ° C.

Preparation Example 2 THF (256 ml), 1,1-diphenylhexyllithium benzene solution (0.78 mmo)
l, 6.1 ml), tert-butyl methacrylate (151 mmo
Polymerization reaction and polymer treatment were carried out in the same manner as in Preparation Example 1 except that the THF solution (66 ml) of l) was used. The obtained polymer was 21.5 g (yield 100%) and was Mu (GPC).
= 2.2 × 10 ⁴ , Mw / Mn = 1.28, Tg = 108 ° C.
Met.

Preparation Example 3 THF (260 ml), 1,1-diphenylhexyllithium benzene solution (0.16 mmo)
l, 1.2 ml), tert-butyl methacrylate (149 mmo
Polymerization reaction and polymer treatment were carried out in the same manner as in Preparation Example 1 except that the THF solution (40 ml) of l) was used. The obtained polymer was 21.3 g (yield 100%) and Mu (GPC) =
It was 11 × 10 ⁴ , Mw / Mn = 1.19, and Tg = 111 ° C.

Preparation Example 4 tert-butylperoxy-2-
Tert-butyl methacrylate (300 g) was added to methyl isobutyl ketone (192 g) containing ethyl hexanoate (TBPO, 20 g), and the mixture was heated to 90 ° C. under a nitrogen stream at 6.5 ° C. for 6.5.
Heat stirring was carried out for an hour. Next, after distilling off methyl isobutyl ketone, acetone was added and the solution was treated in the same manner as in Preparation Example 1. The polymer obtained is 300 g.
(Yield = 100%), Mu (GPC) = 0.57 × 10 ³ , M
w / Mn = 1.96 and Tg = 70 ° C.

Preparation Example 5 tert-Butylmethacrylate (300 g) was added to toluene (300 g) containing TBPO (2.0 g).
g) was added, and the mixture was heated and stirred at 90 ° C. for 7 hours in a nitrogen stream. The obtained solution was treated in the same manner as in Preparation Example 4.
The obtained polymer was 288 g (yield 96%) and Mu (GPC) =
It was 2.2 × 10 ⁴ , Mw / Mu = 2.50, and Tg = 101 ° C.

Preparation Example 6 tert-Butyl methacrylate (200 g) and methyl methacrylate (100 g) were added to methyl isobutyl ketone (192 g) containing TBPO (20 g), and the mixture was heated and stirred at 90 ° C. for 7 hours in a nitrogen stream. I did.
The obtained solution was treated in the same manner as in Preparation Example 4. The obtained polymer was 300 g (yield = 100%) and Mu (GPC) =
It was 0.89 × 10 ³ , Mw / Mn = 1.96, and Tg = 74 ° C.

Comparative Preparation Example 1 2,2'-azobis (2,4-
Tert-Butyl methacrylate in methyl isobutyl ketone (192 g) containing dimethyl valeronitrile) (1.5 g)
(300 g) was added, and the mixture was heated and stirred at 90 ° C. for 6 hours in a nitrogen stream. The obtained solution was treated in the same manner as in Preparation Example 4. The obtained polymer was 300 g (yield = 100%), Mu (GPC) = 0.54 × 10 ³ , Mw / Mn = 1.90,
Tg = 68 ° C.

(Comparative Preparation Example 2) 2,2'-azobis (2,4-
Dimethyl valeronitrile) (1.5 g) in toluene (3
Tert-Butyl methacrylate (300 g) was added to (00 g), and the mixture was heated and stirred at 80 ° C. for 7 hours in a nitrogen stream.
The obtained solution was treated in the same manner as in Preparation Example 4. The obtained polymer was 186 g (yield 62%) and Mu (GPC) = 1.9.
= 10 ⁴ , Mw / Mn = 2.25, and Tg = 97 ° C.

Example 1 4 g of the polymer of Preparation Example 1 was dissolved in methyl isobutyl ketone so that the solid content was 20 wt%, and 15 wt% of triphenylsulfonium hexafluoroantimonate was added to the polymer. .. This solution was spin coated on a metal support at 2000 rpm to form a resist coating having a thickness of 2.0 μ. The coating was dried at 105 ° C for 10 minutes. Then
Irradiation by a super high pressure mercury lamp with a positive mask applied 36mJ / cm ²
Alternatively, the irradiation dose was 54 mJ / cm ² . Then, after further heating at 105 ° C. for 10 minutes, development was performed with a 0.5% aqueous sodium hydroxide solution at 50 ° C. for 60 seconds. The obtained image was observed with a microscope to evaluate the developability. The results are shown in Table 1.

Example 2 A resist composition was prepared, exposed and developed in the same manner as in Example 1 except that the polymer of Preparation Example 2 was used instead of the polymer of Preparation Example 1. The results of evaluation of developability are shown in Table 1.

Example 3 A resist composition was prepared, exposed and developed in the same manner as in Example 1 except that the polymer of Preparation Example 3 was used instead of the polymer of Preparation Example 1. The results of evaluation of developability are shown in Table 1.

Example 4 A resist composition was prepared and exposed in the same manner as in Example 1 except that the polymer of Preparation Example 4 was used instead of the polymer of Preparation Example 1. After that, 105 ℃
After heating for 10 minutes at 50 ° C., development was performed with a 0.1% aqueous solution of sodium hydroxide at 50 ° C. for 60 seconds. The developability evaluation results are shown in Table 2.

Example 5 A resist composition was prepared, exposed and developed in the same manner as in Example 4 except that the polymer of Preparation Example 5 was used in place of the polymer of Preparation Example 4. The developability evaluation results are shown in Table 2.

Example 6 A resist composition was prepared, exposed and developed in the same manner as in Example 4 except that the polymer of Preparation Example 6 was used in place of the polymer of Preparation Example 4. The developability evaluation results are shown in Table 2.

Comparative Example 1 A resist composition was prepared and exposed in the same manner as in Example 1 except that the polymer of Comparative Preparation Example 1 was used in place of the polymer of Preparation Example 1. Then 10
After heating at 5 ° C. for 10 minutes, it was developed with a 0.5% aqueous solution of sodium hydroxide at 50 ° C. for 60 seconds. The results of evaluation of the developability are shown in Table 1. Further, development is performed with a 0.1% aqueous solution of sodium hydroxide at 50 ° C. for 60 seconds,
The obtained developability evaluation results are shown in Table 2.

Comparative Example 2 A resist composition was prepared in the same manner as in Comparative Example 1 except that the polymer of Comparative Preparation Example 2 was used instead of the polymer of Comparative Preparation Example 1, and exposure and development were carried out. It was Table 1 shows the developability evaluation results when developing with a 0.5% aqueous sodium hydroxide solution, and Table 2 shows the developability evaluation results when developing with a 0.1% aqueous sodium hydroxide solution. It was

[0036]

[Table 1]

[0037]

[Table 2]

In Tables 1 and 2, “◯” indicates that a positive positive image is obtained. In “Δ”, a residual film is partially observed in the exposed and developed area. No image appears in "x". Represent each thing.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 21/027

Claims (3)

[Claims] 1. A (meth) acrylic acid ester having a group selected from the group consisting of (a) t-butyl group, benzyl group, α-methylbenzyl group, α, α′-dimethylbenzyl group and trityl group. A resist composition comprising an essential monomer component and not containing a cyano group and (b) a photoactivator that produces an acid when exposed to radiation. 2. The resist composition according to claim 1, wherein the polymer (a) further contains no terminal unsaturated bond. 3. The composition according to claim 1, further comprising a photosensitizer in an amount of 0.01 to 10% by weight based on the polymer (a).