JP3456360B2 - Positive resist composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist composition suitable for use in microfabrication of semiconductors by giving a positive pattern in response to radiation such as ultraviolet rays.

[0002]

2. Description of the Related Art A lithographic process using a resist composition is usually employed for fine processing of semiconductors.
Among resist compositions, positive resist compositions are generally used because of their excellent resolution. In recent years, integrated circuits have become finer with higher integration,
Submicron patterning is required. As a result, there is a demand for a positive resist composition that exhibits a further excellent resolution and is excellent in depth of focus and the like.

The positive type resist generally contains an alkali-soluble component and a radiation sensitive component. In particular,
A novolak resin that contains a novolak resin as an alkali-soluble component and a quinonediazide compound as a radiation-sensitive component, and that an alkali-insoluble quinonediazide compound is decomposed by the action of radiation to generate a carboxylic acid group and becomes alkali-soluble / Functional groups of quinonediazide type resist and resin as an alkali-soluble component are partially protected by a group that is eliminated by the action of an acid, and are themselves alkali-insoluble or sparingly soluble resin, and acid generation as a radiation-sensitive component. There is known a chemically amplified resist containing an agent and changing the solubility of the resin in alkali by utilizing the catalytic action of the acid generated from the acid generator by the action of radiation.

To increase the resolution of the positive resist, it is possible to increase the amount of the radiation sensitive component. However, if the amount of the radiation sensitive component is increased, the light absorption of the resist increases,
There is a problem that the film is easily worn out when the focus is deviated. Thus, it has been generally difficult to sufficiently improve both the resolution and the depth of focus.

[0005]

An object of the present invention is to provide a positive resist composition having a well-balanced improvement in resolution and depth of focus.

As a result of research, it has been found that the presence of a certain compound in a positive resist composition containing an alkali-soluble component and a radiation-sensitive component improves sensitivity and depth of focus. . When a composition obtained by mixing this compound with only an alkali-soluble component is irradiated with radiation and treated with an alkali developing solution, pattern formation cannot be achieved, but the irradiated portion is not irradiated. It was found that the residual film thickness was larger than that of the part and showed a negative tendency. The present invention has been completed based on these findings.

[0007]

That is, the present invention is a novo
It contains an alkali-soluble component that is a rack resin, and contains a quinonediazide compound as a positive radiation-sensitive component that increases the solubility of the novolak resin in alkali by irradiation, and the radiation-irradiated part is exposed by radiation irradiation and subsequent alkali development. A resist composition which is removed to give a positive image, and a compound represented by the following formula (I) or (II) is used as a negative radiation-sensitive compound which reduces the solubility of the alkali-soluble component in alkali by irradiation. A positive resist composition containing the same is provided. (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent hydrogen, halogen, hydroxy, an alkyl group, an alkoxy group, an aryl group or nitro. , R ⁹ and R ¹⁰ are each independently hydrogen, halogen, an alkyl group, an aryl group, nitro, — (CH ₂ )
n-OR ¹¹ or-(CH ₂ ) n-COOR ¹² , wherein R ¹¹ represents hydrogen, an alkyl group, an aryl group or an alkanoyl group, R ¹² represents hydrogen, an alkyl group or an aryl group, and n Represents an integer of 0 to 3, and R ¹³
Represents hydrogen, halogen, an alkyl group, an alkoxy group or an aryl group. However, the compound represented by the formula (I) is an unsubstituted anthracene or an anthracene having a substituent at least at the 2-position and / or the 9-position. )

The action in the presence of a negative radiation sensitive compound in a positive resist can be considered as follows. In a positive type resist, the radiation intensity of the resist film is high on the surface of the film, and the radiation intensity is weaker as it is closer to the substrate. Therefore, the development rate is fast on the surface of the film and slow near the substrate. For this reason,
In the case of a fine pattern, there is a phenomenon in which the film does not come out to the bottom of the film and is not resolved, and in particular, when the focus shifts to the lower side of the substrate surface, the film of the resist is reduced. In this case, when the negative radiation-sensitive compound as described above is present, the absorption of the radiation of the resist film has the effect of slowing down the development speed as it gets closer to the surface of the film, and as a result, the difference between the upper and lower development speeds in the film is reduced. It is presumed that they will be equalized. As a result, a fine pattern is resolved, the film loss when the focus is deviated is reduced, and the depth of focus is expanded. Less than,
The present invention will be described in more detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The resist used in the present invention contains an alkali-soluble component, and the irradiation portion is removed by irradiation with radiation and subsequent alkali development to give a positive image. For example, there is a composition showing the above-mentioned action only with an alkali-soluble component, such as one obtained by converting a part of the phenolic hydroxyl group of the alkali-soluble novolac resin into a quinonediazide sulfonic acid ester, but generally, together with the alkali-soluble component, A material containing a positive radiation-sensitive component that increases the solubility of the alkali-soluble component in alkali upon irradiation is used. As a specific example, as mentioned earlier, also the novolak / quinone diazide-type containing quinonediazide compound as a novolak resin and a radiation-sensitive component as the alkali-soluble component of
Is mentioned.

The alkali-soluble component in the present invention includes those which are alkali-soluble by themselves, such as the novolac resin in the above-mentioned novolak / quinonediazide type resist . The or positive manner tone radiation components, by the action of radiation to undergo a chemical change, it means those that increase the solubility in an alkali alkali-soluble component.

In the case of a novolac / quinonediazide type resist, the novolac resin may be one generally used as an alkali-soluble component in this type of positive resist composition, and usually comprises a phenolic compound and an aldehyde. It is obtained by condensation in the presence of an acid catalyst. Examples of the phenolic compound used for producing the novolac resin include phenol, o-, m- or p-cresol, 2,3-, 2,5-, 3,4- or 3,5-xylenol, 2, 3,5-trimethylphenol, 2
-, 3- or 4-tert-butylphenol, 2-tert
-Butyl-4- or -5-methylphenol, 2-,
4- or 5-methylresorcinol, 2-, 3- or 4-methoxyphenol, 2,3-, 2,5- or 3,5-dimethoxyphenol, 2-methoxyresorcinol, 4-tert-butylcatechol, 2- , 3- or 4-ethylphenol, 2,5- or 3,5-diethylphenol, 2,3,5-triethylphenol,
Examples thereof include 2-naphthol, 1,3-, 1,5- or 1,7-dihydroxynaphthalene, and a polyhydroxytriphenylmethane compound obtained by condensation of xylenol and hydroxybenzaldehyde. These phenolic compounds may be used alone or in combination of two or more.

Aldehydes used in the production of novolac resins include, for example, aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, pivalaldehyde, n-hexylaldehyde, acrolein and crotonaldehyde. Alicyclic aldehydes such as cyclohexanaldehyde, cyclopentanaldehyde, furfural and furylacrolein, benzaldehyde, o-, m- or p-methylbenzaldehyde, p-ethylbenzaldehyde, 2,4-,
Aromatic aldehydes such as 2,5-, 3,4- or 3,5-dimethylbenzaldehyde, o-, m- or p-hydroxybenzaldehyde, o-, m- or p-anisaldehyde and vanillin, phenylacetaldehyde And araliphatic aldehydes such as cinnamic aldehyde. These aldehydes also
Each can be used alone or in combination of two or more if desired. Of these aldehydes, formaldehyde is preferably used because it is industrially easily available.

Examples of acid catalysts used for the condensation of phenolic compounds with aldehydes include inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid and phosphoric acid, formic acid, acetic acid, oxalic acid,
Organic acids such as trichloroacetic acid and p-toluenesulfonic acid, divalent metal salts such as zinc acetate, zinc chloride and magnesium acetate, and the like. These acid catalysts can also be used alone or in combination of two or more kinds. The condensation reaction can be performed according to a conventional method, for example, at a temperature in the range of 60 to 120 ° C. for about 2 to 30 hours.

The novolak resin obtained by condensation is an unreacted phenolic resin when the components having a molecular weight of 1000 or less are expressed as an area ratio in a gel permeation chromatography (GPC) pattern by subjecting to operations such as fractionation. 25% or less of the total pattern area excluding the compound,
Furthermore, it is preferable to set it to 20% or less. Here, the pattern area means that measured using a UV detector of 254 nm, and the molecular weight means the polystyrene equivalent molecular weight.

It is also effective to add an alkali-soluble phenolic compound having a molecular weight of 1,000 or less to the novolak resin thus increased in high molecular weight component. Such an alkali-soluble phenolic compound preferably has at least two phenolic hydroxyl groups in the molecular structure,
For example, Japanese Patent Laid-Open No. 2-275955 (= USP 5,456,995 + US
P 5,456,996) and those described in JP-A-2-2560. When an alkali-soluble phenolic compound having a molecular weight of 1000 or less is used, it is preferably present in the range of 3 to 40% by weight based on the total amount of the novolak resin and the alkali-soluble phenolic compound.
Such a low molecular weight alkali-soluble phenolic compound can be regarded as a part of the alkali-soluble component in the present invention.

The quinonediazide compound may also be one generally used as a radiation sensitive component of a novolak / quinonediazide type resist, and is usually an o-quinonediazide sulfonic acid ester of a compound having a phenolic hydroxyl group. Preferably, 1,2-of a polyhydroxy compound having at least 3 phenolic hydroxyl groups
Naphthoquinone diazide-5- or 4-sulfonic acid ester or 1,2-benzoquinone diazide-4-sulfonic acid ester. Such an ester can be produced by reacting the above-mentioned compound having a phenolic hydroxyl group with an o-quinonediazidesulfonic acid halide in the presence of a base such as triethylamine. Such positive radiation-sensitive quinonediazide components can be used alone or in combination of two or more.

The novolak / quinonediazide type resist is, in addition to the above alkali-soluble component and positive radiation sensitive component, if necessary, other resins, dyes, surfactants and the like, which are commonly used in this field. Ru can also contain additives in small amounts.

The proportion of the alkali-soluble component and the positive radiation-sensitive component in the positive resist composition of the present invention varies depending on the type of resist, but is generally positive with respect to 100 parts by weight of the alkali-soluble component. Radiation-sensitive component 0.1
It is selected from the range of about 50 parts by weight. Novolac /
In the case of a quinonediazide type resist, about 10 to 50 parts by weight of a quinonediazide compound which is a positive radiation-sensitive component is added to 100 parts by weight of a novolak resin which is an alkali-soluble component and an alkali-soluble phenolic compound which is optionally used. It is preferable to include in the ratio of
Yes.

In the present invention , the following formula (I) or (II) is used as a negative radiation-sensitive compound which has the effect of reducing the solubility of the alkali-soluble component in alkali upon irradiation with the positive resist as described above. The compound represented by

[0020]

Where R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ and R ⁸ each independently represent hydrogen, halogen, hydroxy, an alkyl group, an alkoxy group, an aryl group or nitro, and R ⁹ and R ¹⁰ are each independently hydrogen, a halogen, an alkyl group or aryl. group, _{nitro, - (CH 2) n-} oR 11 or - (CH ₂₎ n-COOR
Represents ^12, wherein the R ¹¹ is hydrogen, an alkyl group, an aryl group or an alkanoyl group, R ¹² represents hydrogen, an alkyl group or an aryl group, and n represents an integer of 0 to 3, and R ¹³ is Represents hydrogen, halogen, an alkyl group, an alkoxy group or an aryl group. However, as shown in the formula (I)
The compound can be an unsubstituted anthracene, or at least
Also has an anthracene having a substituent at the 2- and / or 9-positions
It is

In the definitions of the above formulas (I) and (II), the halogen may be fluorine, chlorine, bromine, etc., and the alkyl group and the alkoxy group each have, for example, about 1 to 6 carbon atoms. The alkanoyl group may have about 2 to 6 carbon atoms including the carbon of the carbonyl, and the aryl group may be phenyl, naphthyl, anthryl and the like. Substituents such as alkyl, alkoxy, hydroxy, carboxy, halogen and nitro may be bonded to the aromatic ring such as phenyl, naphthyl and anthryl constituting the aryl.

Anthracene compounds of formula (I)
Is an unsubstituted anthracene or at least the 2-position and /
Alternatively, it is anthracene having a substituent at the 9-position. Specific examples of anthracene having a substituent at the 2-position and / or the 9-position and optionally having a substituent at another position include:
Some examples are as follows.

9-anthracenemethanol, 9-anthracenemethanolacetate, 9-anthracenecarboxylic acid, 2-methylanthracene, 2-ethylanthracene, 2-t-butylanthracene, 2-methyl-9,10-dimethoxyanthracene, 2- Methyl-9,10-diethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 2-ethyl-9,10-diethoxyanthracene, 2-t-butyl-9,10-dimethoxyanthracene, 2-t- Butyl-9,10-diethoxyanthracene, 2,3-dimethyl-9,10-dimethoxyanthracene, 4- (9-anthrylcarbonyloxy) benzoic acid, 4- (9-anthrylcarbonyloxy) -3-hydroxy Benzoic acid, 1,4,9,10-anthra Ntetororu, 4,9,10- trihydroxy-1-anthryl 9-
Anthracene carboxylate etc.

These negative-working radiation-sensitive compounds reduce the solubility of the alkali-soluble component in alkali upon irradiation with radiation, but it is sufficient that they are present in an amount such that the positive action of the positive resist is not impaired. It is preferable to make it exist in a ratio of about 0.01 to 5 parts by weight per 100 parts by weight of the soluble component. If the amount is too small, the effect of the present invention will be insufficient, and if the amount is too large, the positive action of the positive resist may be hindered.

[0026] The positive resist composition of the present invention, usually,
A resist solution is prepared by dissolving each of the above components in a solvent and applied onto a substrate such as a silicon wafer. The solvent used here may be any one that dissolves each component, has an appropriate drying rate, and gives a uniform and smooth coating film after the solvent is evaporated, and it is usually used in this field. Can be For example, glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, glycols such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether and propylene glycol monoethyl ether. Ethers, esters such as ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate, ketones such as acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone, cyclic esters such as γ-butyrolactone and the like. To be These solvents can be used alone or in combination of two or more.

The resist film coated and dried on the substrate is irradiated with radiation for patterning, and optionally post-exposure baked, and then developed with an alkali developing solution. The alkaline developer used here can be various alkaline aqueous solutions used in this field, but in general, an aqueous solution of tetramethylammonium hydroxide is often used.

[0028]

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. Parts in the examples are by weight unless otherwise specified. In the examples and comparative examples,
The novolak resins A and B shown below and the negative radiation-sensitive compounds C to U were used.

Novolac resin A: m-cresol / p-cresol / formaldehyde in a molar ratio of 40/60/80, reacted under reflux in the presence of an oxalic acid catalyst according to a conventional method, and then obtained by fractionation. A novolac resin having an average molecular weight of 8,000, wherein the area ratio of the polystyrene reduced molecular weight of 6000 or less to the total pattern area excluding the pattern area of unreacted cresol in the GPC pattern is 34%, and the area ratio of the polystyrene reduced molecular weight of 1000 or less is 15%. What is%.

Novolac resin B: A resin produced in the same manner as the above novolak resin A except that the molar ratio of m-cresol / p-cresol / formaldehyde is 60/40/80.

Negative radiation-sensitive compound C: 9-anthracenemethanol. D: 9-anthracene methanol acetate. E: 9-anthracene carboxylic acid. F: Anthracene. G: 2-Ethyl-9,10-dimethoxyanthracene. H: 4- (9-anthrylcarbonyloxy) benzoic acid. I: 4- (9-anthrylcarbonyloxy) -3-hydroxybenzoic acid. J: 4,9,10-trihydroxy-1-anthryl
9-anthracene carboxylate. K: 1,4,9,10-anthracentetrol. L: 2-ethyl-9,10-diethoxyanthracene. M: 2-t-butyl-9,10-diethoxyanthracene. N: 2-t-butyl-9,10-dimethoxyanthracene. O: 2-methyl-9,10-dimethoxyanthracene. P: 2-methyl-9,10-diethoxyanthracene. Q: 2,3-dimethyl-9,10-dimethoxyanthracene. R: 2-methylanthracene. S: 2-ethylanthracene. T: 2-t-butylanthracene. U: Phenothiazine.

Examples 1-20 and Comparative Examples 1-2 Using the above novolak resins A and B in the amounts shown in Table 1,
Furthermore, the following formula

[0033]

2,4,4-trimethyl-having the structure
Reaction of 2 ', 4', 7-trihydroxyflavan with 1,2-naphthoquinonediazide-5-sulfonic acid chloride 3 parts of a positive radiation sensitive component consisting of a condensate with a molar ratio of 1: 2.6, an additive 4,4 '-(2-Hydroxybenzylidene) di-2,6-xylenol as an ingredient, and the negative radiation-sensitive compound shown in Table 1 were used in respective amounts, and these were mixed with 45 parts of a 2-heptanone solvent. And dissolved.
However, in the comparative example, no negative radiation sensitive compound was used. Each of the resulting solutions was filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist solution.

A silicon wafer treated with hexamethyldisilazane (HMDS) was spin-coated with each of the resist solutions obtained above so that the film thickness after drying was 0.85 μm. Prebaking was performed on a direct hot plate under the conditions of 90 ° C. and 60 seconds. Using the i-line stepper ["NSR-2005i9C" manufactured by Nikon Corporation, NA = 0.57, σ = 0.60] on the wafer thus formed with the resist film, the exposure amount is changed stepwise to form a line-and-space pattern. Exposed. Next, on a hot plate, 110 ℃, 60
After performing the post exposure bake under the condition of second,
Paddle development was performed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide aqueous solution.

The developed pattern was observed with a scanning electron microscope, and the effective sensitivity, resolution and depth of focus of each pattern were evaluated as follows, and the results are shown in Table 1.

Effective sensitivity: The line and space pattern of 0.40 μm was displayed at an exposure dose at which the cross section became 1: 1.

Resolution: Displayed as the minimum line width of the line and space pattern separated by the exposure amount of the effective sensitivity.

Depth of focus: 0.40μ in effective sensitivity
m Line-and-space pattern is displayed in the range of focus where resolution is achieved without film loss.

[0040]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example No. Tree negative fat component Effective sensitivity Resolution Resolution Depth of focus ─────────────────────────────── Example 1 A / 5 part B / 5 part C / 0.3 part 300 msec 0.34 μm 1.4 μm 〃 2 A / 6 part B / 4 part C / 0.3 part 250 msec 0.35 μm 1.2 μm 〃 3 〃 〃 D / 0.3 part 310 msec 0.32 μm 1.6 μm 〃 4 A / 4 part B / 6 part E / 0.3 part 290 msec 0.35 μm 1.2 μm 〃 5 A / 5 part B / 5 part F / 0.3 part 280 msec 0.35 μm 1.2 μm 〃 6 A / 6 part B / 4 part G / 0.3 part 300 msec 0.32 μm 1.6 μm 〃 7 A / 7 parts B / 3 parts H / 0.3 parts 310 msec 0.34 μm 1.2 μm 〃 8 〃 〃 I / 0.3 parts 300 msec 0.34 μm 1.2 μm 〃 9 〃 〃 J / 0.3 parts 320 msec 0.34 μm 1.2 μm 〃 10 〃 〃 K / 0.3 part 290 msec 0.35 μm 1.2 μm 〃 11 A / 6 part B / 4 part L / 0.3 part 280 msec 0.33 μm 1.4 μm 〃 12 〃 〃 M / 0.3 part 270 msec 0.34 μm 1.4 μm 〃 13 〃 N / 0.3 part 280 msec 0.33 μm 1.4 μm 〃 14 〃 〃 O / 0.3 part 300 msec 0.33 μm 1.4 μm 〃 15 〃 〃 P / 0.3 part 300 msec 0.33 μm 1.4 μm 〃 16 〃 〃 300 m 0.3 0.4 part μm 1.4 μm 〃 17 〃 〃 R / 0.3 part 250 msec 0.35 μm 1.2 μm 〃 18 〃 S / 0.3 part 260 msec 0.35 μm 1.2 μm 〃 19 〃 〃 T / 0.3 part 260 msec 0.35 μm 1.2 μm 〃 20 Part B / 3 Part U / 0.3 Part 310 msec 0.35 μm 1.2 μm ──────────────────────────────── Comparative Example 1 A / 5 part without B / 5 part 260 msec 0.4 μm 0.6 μm 〃 2 A / 6 part without B / 4 part 310 msec 0.375 μm 0.8 μm ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━

[0041]

According to the present invention, a positive resist composition having excellent resolution and depth of focus is provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-269350 (JP, A) JP-A-1-307740 (JP, A) JP-A-7-319155 (JP, A) JP-A-7- 84364 (JP, A) JP 8-320554 (JP, A) JP 9-15850 (JP, A) JP 10-69071 (JP, A) JP 63-27829 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (2)

(57) [Claims] 1. A quinonediazide compound is contained as a positive radiation-sensitive component which contains an alkali-soluble component which is a novolac resin and which increases the solubility of the novolak resin in alkali upon irradiation, and irradiation and subsequent alkali development. Which is a resist composition which gives a positive image by removing the radiation-exposed portion by means of the following formula (I) or (II) as a negative radiation-sensitive compound which reduces the solubility of the alkali-soluble component in alkali by radiation: A positive resist composition comprising a compound represented by: (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent hydrogen, halogen, hydroxy, an alkyl group, an alkoxy group, an aryl group or nitro. , R ⁹ and R ¹⁰ are each independently hydrogen, halogen, an alkyl group, an aryl group, nitro, — (CH ₂ )
n-OR ¹¹ or-(CH ₂ ) n-COOR ¹² , wherein R ¹¹ represents hydrogen, an alkyl group, an aryl group or an alkanoyl group, R ¹² represents hydrogen, an alkyl group or an aryl group, and n Represents an integer of 0 to 3, and R ¹³
Represents hydrogen, halogen, an alkyl group, an alkoxy group or an aryl group. However, the compound represented by the formula (I) is an unsubstituted anthracene or an anthracene having a substituent at least at the 2-position and / or the 9-position. ) Wherein the alkali-soluble component per 100 parts by weight, formula (I) or (II) compound composition of claim 1 Symbol placement is present in an amount of 0.01 to 5 parts by weight indicated by.