JP3438518B2 - 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 the production of semiconductors by providing a positive pattern in response to radiation such as ultraviolet rays.

[0002]

2. Description of the Related Art A positive resist containing a novolak resin as an alkali-soluble component and a quinonediazide compound as a radiation-sensitive component is a quinonediazide compound which is decomposed by the action of radiation to generate a carboxylic acid group, which is converted from an alkali-insoluble state to an alkali. Taking advantage of the fact that it is in a soluble state, a positive type image is provided by irradiation of radiation through a mask (so-called patterning exposure) and alkali development. Such a novolac / quinonediazide-based positive resist is generally used in the production of integrated circuits because of its excellent resolution.

In recent years, integrated circuits have become finer with higher integration, and submicron pattern formation has been required. As a result, positive resists are required to have excellent resolution and profile (pattern shape). In other words, as the pattern becomes finer, the surface (top) becomes more rounded, and the inclination (taper) between the top and the bottom surface (bottom) of the pattern becomes noticeable, so that the mask shape during patterning exposure is faithful. Therefore, a positive resist composition that improves these properties and gives a good profile is required.

The simplest means for improving the profile is to increase the transparency of the resist, specifically, to reduce the amount of radiation-sensitive component. Since the resolution is reduced to
Not desirable. As another means for improving the profile, it is conceivable to increase the hydrophobicity of the novolac resin, but increasing the hydrophobicity of the novolac resin has a drawback that sensitivity is generally lowered. Thus, it has generally been difficult to improve the profile without compromising sensitivity and resolution.

[0005]

An object of the present invention is to provide a positive resist composition having an excellent balance of various performances such as sensitivity, resolution and profile.

The inventors of the present invention have conducted extensive studies to achieve such an object, and as a result, some compounds in a positive resist composition containing a novolac resin as an alkali-soluble component and a quinonediazide compound as a radiation-sensitive component. The present inventors have completed the present invention by discovering that the presence of ## EQU1 ## significantly improves the profile without lowering the sensitivity and resolution.

[0007]

Means for Solving the Problems] The present invention is an alkali-soluble novolak resin, a quinonediazide radiation sensitive agent and contains an acid generator produced an acid by the action of an alkali developer, the acid generating agent Shown by the following formula (Ia)
There is provided a compound der Ru positive resist compositions. (In the formula, Y represents an oxygen atom, and Z is And R represents a camphor group.) The present invention also provides, in addition to the above novolak resin, radiation-sensitive agent and acid generator, a compound having a sensitizing effect on the wavelength of radiation used for patterning exposure. A positive resist composition containing the same is also provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The alkali-soluble novolak resin used in the present invention may be one that is generally used as an alkali-soluble component of a positive resist composition, and usually comprises a phenolic compound and an aldehyde as an acid catalyst. Can be obtained by condensation in the presence of 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, formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, pivalaldehyde, n-hexylaldehyde, aliphatic aldehydes such as 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 are 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 chromatograph (GPC) pattern by performing an operation such as fractionation. It is preferably 25% or less, and more preferably 20% or less with respect to the entire pattern area excluding the compound. 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 1000 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.

Further, the quinonediazide radiation sensitive agent used in the present invention may be one generally used as a radiation sensitive agent for a positive resist composition, and is usually an o-quinonediazide compound having a phenolic hydroxyl group. It can be a sulfonate ester. Preferably, 1,2-naphthoquinonediazide-5- or-of a polyhydroxy compound having at least three phenolic hydroxyl groups is used.
4-sulfonic acid ester or 1,2-benzoquinonediazide-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. The o-quinonediazide sulfonic acid halide is particularly preferably 1,2-naphthoquinonediazide-5-sulfonic acid chloride. Such quinonediazide radiation-sensitive agents can be used alone or in combination of two or more. The radiation-sensitive agent is usually present in the range of usually 10 to 100% by weight, preferably 10 to 50% by weight, based on the total amount of the novolak resin and the above-mentioned alkali-soluble phenolic compound used as desired.

The positive resist composition of the present invention contains an acid generator in addition to the alkali-soluble novolac resin and the quinonediazide radiation sensitive agent. This acid generator is
Ru compounds der capable of generating an acid by the action of an alkali developer. The acid generator used in the present invention is decomposed by the action of an alkali developing solution, and it is preferable that all the decomposed products are alkali-soluble.

The acid generator Ru used in the present invention has the formula (I a)
Is a compound represented by .

[0016] (In the formula, Y represents an oxygen atom, and Z is Represents, and R represents a camphor group)

[0017] with the camphor group, camphor (campho
It means a monovalent group derived from r), and particularly a 10-camphor group, that is, a group in which a sulfonic acid group is removed from, for example, 10-camphorsulfonic acid is preferable.

Among the above-mentioned acid generators, some are known as acid generators which are decomposed by the action of exposure radiation in a so-called chemically amplified resist composition utilizing the catalytic action of acid. The acid generator used in the present invention does not need to be sensitive to the wavelength of radiation used for patterning exposure, and may be any acid as long as it decomposes with an alkali developer used in development after patterning exposure to generate an acid. . Due to the presence of this acid generator, even at a location where the decomposition of the quinonediazide radiation-sensitive agent by patterning exposure is insufficient, it easily dissolves in an alkali developing solution due to the interaction with the acid generated from this acid generator, resulting in a pattern. It is estimated that an image faithful to is formed. Therefore, the acid generator according to the present invention can be said to be a dissolution accelerating aid and may be present in an amount necessary to act in this manner, but generally it is 0.5 to 20 based on the total solid content in the resist composition. It is preferably present in the range of about wt%. If the amount is too small, the effect of the present invention will be insufficient, and if the amount is too large, the non-exposed area will also be easily dissolved in the alkaline developing solution, which may rather worsen the profile.

The compound represented by the formula ( Ia) can be produced according to a known method, and since some compounds are commercially available, the commercially available products can be used as they are .

Specific examples of the compound represented by the formula (Ia) include the followings.

[0021]

In addition to the above-mentioned alkali-soluble novolac resin, quinonediazide-based radiation-sensitive agent and acid generator that decomposes to generate an acid by the action of an alkali developer, it is further sensitive to the wavelength of radiation during patterning exposure. Incorporation of a compound having a sensitizing effect on the radiation in order to bring about the above results in even better resolution. When such a sensitizer is used, it is generally preferable that the sensitizer be present in the resist composition in the range of about 0.01 to 5% by weight based on the total solid content.

The sensitizer used here may be one that is sensitive to the wavelength of the radiation used for patterning exposure, and is, for example, an anthracene-based compound or a phenothiazine-based compound, in particular the following formula (IV) or (V) The compound shown by is mentioned.

[0025]

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, 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.

In the definitions of the above formulas (IV) and (V), 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.

Among the above-mentioned sensitizers, anthracene compounds represented by the formula (IV) are preferable, and particularly preferable are unsubstituted anthracene and at least 2
And anthracene having a substituent at the 9- and / or 9-position. Having a substituent at the 2- and / or 9-position,
Specific examples of the anthracene that may have a substituent at another position include the following.

9-anthracenemethanol, 9-anthracenemethanolacetate, 9-anthracenecarboxylic acid, 2-methylanthracene, 2-ethylanthracene, 2-t-butylanthracene, 2-methyl-9,1
0-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-hydroxybenzoic acid, 1,4 , 9,10-anthracene tetrol, 4,9,10-trihydroxy-1-anthryl 9-anthracene carboxylate and the like.

The positive resist composition of the present invention is usually prepared by dissolving each of the above components in a solvent to prepare a resist solution.
It is applied on a substrate such as a silicon wafer. The solvent used here dissolves each component and has an appropriate drying rate,
Any solvent can be used as long as it gives a uniform and smooth coating film after the solvent is evaporated, and it can be one commonly used in this field. For example, ethyl cellosolve acetate,
Glycol ether esters such as methyl cellosolve acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, glycol ethers such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether and propylene glycol monoethyl ether, ethyl lactate, Esters such as butyl acetate, amyl acetate and ethyl pyruvate, ketones such as 2-heptanone and cyclohexanone, γ-
Examples thereof include cyclic esters such as butyrolactone. These solvents can be used alone or in combination of two or more. Further, the resist composition of the present invention may further contain a small amount of additives conventionally used in this field, such as resins and dyes other than novolac resins, if necessary.

The resist film coated and dried on the substrate is irradiated with radiation through a mask for patterning, 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.

[0032]

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. In the examples, part means part by weight.

Examples 1 to 3 and Comparative Example 1 (a) Novolac resin m-cresol / p-cresol / formaldehyde in a molar ratio of 40/60/80 under reflux in the presence of an oxalic acid catalyst according to a conventional method. A novolak resin having a weight average molecular weight of 8000 obtained by reacting and then fractionating, and having an area ratio of 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 A polystyrene-converted molecular weight of 1000 or less having an area ratio of 15% was used.

(B) Quinonediazide type photosensitizer The following formula

[0035]

2,4,4-trimethyl-having the structure
2 ', 4', 7-trihydroxyflavan and 1,2-
With naphthoquinonediazide-5-sulfonic acid chloride,
A condensate having a reaction molar ratio of 1: 2.4 was used.

(C) Acid generator The following compounds were used. The numbers correspond to the numbers of the compounds exemplified above.

(1) N- (10-camphorsulfonyloxy) succinimide .

( D) Preparation and Evaluation of Resist Solution 10 parts of the above novolak resin, 3.5 parts of the above quinonediazide sensitizer, 4,4 ′-(2-hydroxybenzylidene) di-2,6 as an additive 5 parts of xylenol and 45 parts of 2-heptanone as solvent were mixed. After adding each acid generator shown in Table 1 to this liquid,
A resist solution was prepared by filtering with a 0.2 μm fluororesin filter. The amount of the acid generator in Table 1 is represented by% by weight based on the total solid content of the resist before adding it.

A silicon wafer treated with hexamethyldisilazane (HMDS) was spin-coated with each resist solution obtained above so that the film thickness after drying was 1.06 μm.
Prebaking was performed on a direct hot plate under the conditions of 90 ° C. and 60 seconds. The i-line stepper ["N
SR 2005i9C ", NA = 0.57, σ = 0.60] was used to expose the line-and-space pattern by gradually changing the exposure amount. After that, on a hot plate at 110 ° C. and 60 ° C.
Post exposure bake was carried out under the condition of second, and then paddle development was carried out for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide aqueous solution. The pattern after development is observed with a scanning electron microscope, each effective sensitivity,
Evaluate the resolution and profile as follows,
The results are shown in Table 1.

Effective Sensitivity: The line and space pattern of 0.50 μm was displayed by the exposure amount at which the cross section becomes 1: 1.

Resolution: The minimum line width of the line-and-space pattern separated by the exposure amount of the effective sensitivity is shown.

Profile: 0.50 in effective sensitivity
For the μm line and space pattern, the ratio of the top width (T) and the bottom width (B) of the line part (T /
Displayed in B). The closer the T / B is to 1, the better the rectangular shape is.

[0044]

[Table 1]

Examples 4 to 15 In these examples, the following sensitizers were blended together with the acid generator. The sensitizers are indicated by respective symbols below.

A: 9-anthracenemethanol. B: 9
-Anthracene methanol acetate. C: 9-anthracene carboxylic acid. D: Anthracene. E: 2-Ethyl-9,10-dimethoxyanthracene. F: 4- (9-
Anthrylcarbonyloxy) benzoic acid. G: 2-methyl-9,10-dimethoxyanthracene. H: 2-t-
Butyl-9,10-dimethoxyanthracene. I: 2-
Ethyl-9,10-diethoxyanthracene. J: 2-
t-Butylanthracene. K: phenothiazine.

2-containing the novolac resin before addition of the acid generator prepared in (d) of Example 1, the photosensitizer and the additive
The acid generator and the sensitizer shown in Table 2 were added to the heptanone solution, and then filtered through a 0.2 μm fluororesin filter to prepare a resist solution. The amounts of the acid generator and the sensitizer in Table 2 are shown in% by weight based on the total solid content of the resist before adding them. Using this resist solution, formation of a resist film, formation of a pattern, and evaluation were performed in the same manner as in Example 1. The evaluation results are also shown in Table 2.

[0048]

[Table 2] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example No. Acid generator Sensitizer Effective sensitivity Resolution profile (T / B ) ───────────────────────────── Example 4 (1) / 5% A / 0.5% 265 msec 0.35 μm 0.92 〃 5 (1) / 5% A / 1.5% 280 〃 0.33 〃 0.90 〃 6 (1) / 5% B / 1.5% 280 〃 0.32 〃 0.90 〃 7 (1) / 5% C / 1.5% 255 〃 0.35 〃 0.93 〃 8 (1) / 5% D / 1.5% 265 〃 0.34 〃 0.92 〃 9 (1) / 5% E / 1.5% 280 〃 0.32 〃 0.93 〃 10 (1) / 5% F / 1.5% 230 〃 0.34 〃 0.94 〃 11 (1) / 5% G / 1.5% 280 〃 0.32 〃 0.92 〃 12 (1) / 5% H / 1.5% 260 〃 0.32 〃 0.93 〃 13 (1) / 5% I / 1.5% 260 〃 0.32 〃 0.93 〃 14 (1) / 5% J / 1.5% 250 〃 0.34 〃 0.94 〃 15 (1) / 5% K / 1.5% 280 〃 0.33 〃 0.93 ━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━

[0049]

INDUSTRIAL APPLICABILITY According to the present invention, a positive resist composition which can improve various performances such as sensitivity and resolution, and in some cases, can improve the performance and the profile can be remarkably improved. Will be provided. This composition has an excellent balance of various performances such as sensitivity, resolution, profile, and depth of focus.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-107755 (JP, A) JP-A-3-28849 (JP, A) JP-A-5-181279 (JP, A) JP-A-1- 307740 (JP, A) JP 7-319155 (JP, A) JP 7-84364 (JP, A) JP 8-320554 (JP, A) JP 9-15850 (JP, A) JP 63-27829 (JP, A) Tokuhyo 5-507563 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (4)

(57) [Claims] 1. A alkali-soluble novolak resin, a quinonediazide radiation sensitive agent and contains an acid generator produced an acid by the action of an alkali developer, the acid generating agent
The positive resist composition comprising a compound der Rukoto represented by the following formula (Ia). (In the formula, Y represents an oxygen atom, and Z is Represents, and R represents a camphor group) 2. The composition according to claim 1, which contains an acid generator in an amount of 0.5 to 20% by weight based on the total solid content of the composition. 3. A further composition according to claim 1 or 2 containing a compound of sensitizing action with respect to the wavelength of the radiation used for patterning exposure. 4. A compound having a sensitizing effect on the wavelength of radiation used for patterning exposure is represented by the following formula (IV) or (V): (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
Is hydrogen, halogen, an alkyl group composition of claim 3 represented by an alkoxy group or an aryl group).