JP4566619B2 - Negative resist composition and resist pattern forming method - Google Patents

Description

  The present invention relates to a negative resist composition and a resist pattern forming method using the negative resist composition.

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology.
In order to reproduce a pattern with fine dimensions, a resist material having high resolution is required, and a chemically amplified resist composition is preferably used.

The chemically amplified negative resist comprises (A) an alkali-soluble resin, (B) an acid generator component, and (C) a cross-linking agent. Upon formation of a resist pattern, (B) an acid generator is formed by exposure. When an acid is generated from the component, the acid acts to cause cross-linking between the (A) resin component and the (C) cross-linking agent, resulting in alkali insolubility.
As conventional examples of the chemically amplified negative resist, for example, the following Patent Documents 1 and 2 can be cited.
JP 2001-56555 A JP 2001-133777 A

In recent years, as the demand for high resolution increases, it has become an important problem to reduce line width roughness (hereinafter referred to as “LWR”) in which the line width of a line pattern becomes non-uniform. The conventional chemical amplification type negative resist composition is insufficient in improving the LWR.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a negative resist composition and a method for forming a resist pattern that have high resolution and can reduce LWR. .

In order to achieve the above object, the present invention employs the following configuration.
That is, the negative resist composition of the present invention includes an alkali-soluble resin (A), an acid generator (B) that generates an acid upon irradiation with radiation, and a negative resist composition containing a crosslinking agent (C). The component (A) is a copolymer having a unit (a1) represented by the following general formula (I) and a unit (a2) represented by the following general formula (II), and the component (B) is , An oxime sulfonate acid generator, wherein the component (C) is a mixture of a melamine crosslinking agent and a urea crosslinking agent, tri-n-octylamine or tri-n-dodecylamine, and It contains the compound (D) represented by Formula (1), It is characterized by the above-mentioned.

(In the formula (I), R represents a hydrogen atom or a methyl group, m represents an integer of 1 to 3. In the formula (II), R represents a hydrogen atom or a methyl group, and R ₁ has 1 to ₁ carbon atoms. 5 represents an alkyl group, and n represents an integer of 0 or 1 to 3. In formula (1) , R ′ and R ″ each independently represents an alkyl group having 1 to 5 carbon atoms. .)

The present invention, on a substrate, by using the negative resist composition of the present invention to form a negative resist film, after the selective exposure process on the negative resist film, heat treatment (post It performs exposure baking), to provide a resist pattern shape forming method and forming a resist pattern by performing development processing thereafter.

  In the present invention, exposure includes electron beam irradiation. Further, both “unit” and “structural unit” mean a monomer unit constituting the polymer.

  According to the present invention, a negative resist composition having high resolution and capable of reducing LWR is obtained, and this is used to form a resist pattern with good resolution and improved LWR. be able to.

  The negative resist composition of the present invention comprises an alkali-soluble resin (A), an acid generator (B) that generates an acid upon irradiation with radiation, a crosslinking agent (C), and a compound represented by the above general formula (1) (D) is contained.

Compound (D) (hereinafter sometimes referred to as component (D))
First, the compound (D) will be described. The compound (D) represented by the general formula (1) is soluble in an alkali developer, and changes in polarity by the action of an acid to become insoluble in alkali. It is considered that the reaction causing such a change in polarity involves the elimination reaction of H ₂ O.

In the general formula (1), R ′ and R ″ each independently represents an alkyl group having 1 to 5 carbon atoms. The alkyl group may be linear or branched. Carbon number of R ′ and R ″ Is preferably 1 to 3, particularly preferably a methyl group. R ′ and R ″ may be the same or different. More preferably, R ′ and R ″ are the same.
Further, p is 2 or 3, and 2 is more preferable because the solubility in an alkali developer is further lowered by the action of an acid. This is considered to be because when p is 2, the uniformity of the reaction that causes the change in polarity is better than when p is 3. The substitution position when p is 2 may be the meta position or the para position, but the meta position is more preferred.
As the component (D), any one of them may be used alone, or two or more compounds (D) may be used in combination.
Compound (D) is commercially available.

  The content of the component (D) in the negative resist composition of the present invention is preferably 1.0 to 7.0 parts by mass, and 2.0 to 5.0 parts by mass per 100 parts by mass of the component (A) described later. More preferred. If the content of the component (D) is less than the above range, the effect of addition may be insufficient, and if it is more than the above range, the sensitivity may decrease significantly, and a resist pattern corresponding to the mask pattern is formed. Sometimes it is not possible.

Alkali-soluble resin (A) (hereinafter sometimes referred to as component (A))
The alkali-soluble resin (A) is not particularly limited as long as it is soluble in an alkali developer and becomes insoluble by interaction with the cross-linking agent component. You can choose from what is listed.
For example, a novolak resin, polyhydroxystyrene, and a copolymer having the (a1) unit represented by the following general formula (I) and the (a2) unit represented by the following general formula (II) are preferably used. .

(In the formula, R represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 3.)

(In the formula, R represents a hydrogen atom or a methyl group, R ₁ represents an alkyl group having 1 to 5 carbon atoms, and n represents 0 or an integer of 1 to 3).

  In the unit (a1) represented by the general formula (I), R is a hydrogen atom or a methyl group, and is preferably a hydrogen atom. m is an integer of 1-3. Of these, m is preferably 1. The position of the hydroxyl group may be any of the o-position, the m-position, and the p-position. However, it is preferable that m is 1 and a hydroxyl group is present in the p-position because it is readily available and inexpensive. When m is 2 or 3, arbitrary substitution positions can be combined.

In the unit (a2) represented by the general formula (II), R is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.
R ₁ is a linear or branched alkyl group having 1 to 5 carbon atoms, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group. Group, neopentyl group and the like. Industrially, a methyl group or an ethyl group is preferable.
The n is 0 or an integer of 1 to 3. Of these, n is preferably 0 or 1, and is particularly preferably 0 industrially.
In addition, when n is 1 to 3, the substitution position of R ₁ may be any of the o-position, m-position and p-position, and when n is 2 or 3, any substitution The positions can be combined.

  Among these, as the component (A), a copolymer comprising the (a1) unit and the (a2) unit is particularly preferable because a rectangular resist pattern can be obtained. The ratio of the (a1) unit to the (a2) unit ((a1) unit: (a2) unit) in the copolymer is preferably in the range of 90 to 70:10 to 30, preferably 85 to 75:15. Most preferred is 25. .

In addition, as the component (A), 3 to 40 mol% of the hydrogen atoms of the hydroxyl group of polyhydroxystyrene may be substituted with an alkali-insoluble group, thereby inhibiting alkali solubility. Alternatively, in the copolymer composed of the (a1) unit and the (a2) unit, 5-30 mol% of the hydrogen atom of the hydroxyl group in the (a1) unit is substituted with an alkali-insoluble group, and the alkali solubility is adjusted. It may be used.
The alkali-insoluble group is a substituent that lowers the alkali solubility of the unsubstituted alkali-soluble resin. For example, a tertiary alkoxycarbonyl group such as a tert-butoxycarbonyl group or a tert-amyloxycarbonyl group, methyl Groups, lower alkyl groups such as ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group. Among these, lower alkyl groups, particularly isopropyl groups, are preferred because they are not easily affected by the surrounding environment where resist patterning is performed and a good resist pattern can be obtained.

The mass average molecular weight of the alkali-soluble resin (A) (in terms of polystyrene, the same applies hereinafter, hereinafter referred to as Mw) is preferably 1000 to 10,000, and particularly 2000 in a chemically amplified negative resist for KrF and electron beam (EB). -4000 is more preferable.
Further, the dispersity (Mw / Mn, Mn is the number average molecular weight) of the alkali-soluble resin (A) is preferably about 1.0 to 2.5, and more preferably 1.0 to 1.5.
The content of the resin component (A) in the negative resist composition of the present invention may be adjusted according to the resist film thickness to be formed.

Acid generator (B) (hereinafter sometimes referred to as component (B))
The component (B) can be used without particular limitation from known acid generators used in conventional chemically amplified resist compositions.
Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, There are various known diazomethane acid generators such as diazomethane nitrobenzyl sulfonates, imino sulfonate acid generators and disulfone acid generators.
Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethane. Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethane Sulfonate, its heptafluoropropane sulphonate or its Nafluorobutane sulfonate, trifluoromethane sulfonate of monophenyldimethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, trifluoromethane sulfonate of diphenyl monomethylsulfonium, heptafluoropropane sulfonate or nonafluorobutane sulfonate thereof, (4- Trifluoromethanesulfonate of methylphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoromethanesulfonate of (4-methoxyphenyl) diphenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, tri (4 -Tert-bu Le) trifluoromethanesulfonate triphenylsulfonium, its like heptafluoropropane sulfonate or nonafluorobutane sulfonates.

  Specific examples of the oxime sulfonate acid generator include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino)- Phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methylsulfonyloxyimino) -p-bromophenylacetonitrile and the like can be mentioned. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

Among diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, Examples include bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

(B) As a component, these acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, as the component (B), an oxime sulfonate acid generator is preferable because it has high crosslinking efficiency and can achieve high resolution.
Content of (B) component in the negative resist composition of this invention is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. If the amount is less than the above range, pattern formation may not be sufficiently performed, and if the amount exceeds the above range, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

・ Crosslinking agent (C) (hereinafter also referred to as component (C))
As a crosslinking agent (C), it can use without specifically limiting from the well-known crosslinking agent currently used in the conventional chemically amplified resist composition. For example, at least one selected from the group consisting of melamine-based crosslinking agents, urea-based crosslinking agents, ethyleneurea-based crosslinking agents, and glycoluril-based crosslinking agents is preferably used.
A crosslinking agent (C) may be used individually by 1 type, and may use 2 or more types together. In particular, a mixture of a melamine crosslinking agent and a urea crosslinking agent is preferable because resolution and resist pattern shape are improved. The mixing ratio of the melamine crosslinking agent and the urea crosslinking agent is preferably in the range of 9: 1 to 1: 9, and most preferably in the range of 4: 6 to 6: 4. High resolution can be achieved by combining the mixture of the crosslinking agent and the oxime sulfonate acid generator, and the crosslinking efficiency is increased, which is preferable.

Specific examples of the melamine-based crosslinking agent include compounds in which melamine is reacted with formaldehyde, or formaldehyde and a lower alcohol, and a hydrogen atom of an amino group is substituted with a hydroxymethyl group or a lower alkoxymethyl group. Methylmelamine is preferably used.
Specific examples of the urea-based crosslinking agent include compounds in which urea is reacted with formaldehyde, or formaldehyde and a lower alcohol, and a hydrogen atom of an amino group is substituted with a hydroxymethyl group or a lower alkoxymethyl group, such as bismethoxymethyl. Urea is preferably used.

  Specific examples of the ethylene urea crosslinking agent include compounds represented by the following general formula (III).

(In the formula, R ¹ and R ² are each independently a hydroxyl group or a lower alkoxy group, and R ³ and R ⁴ are each independently a hydrogen atom, a hydroxyl group, or a lower alkoxy group.)
When R ¹ and R ² are lower alkoxy groups, they are preferably alkoxy groups having 1 to 4 carbon atoms, and may be linear or branched. R ¹ and R ² may be the same or different from each other. More preferably, they are the same.
When R ³ and R ⁴ are lower alkoxy groups, they are preferably alkoxy groups having 1 to 4 carbon atoms, and may be linear or branched. R ³ and R ⁴ may be the same or different from each other. More preferably, they are the same.

The compound represented by the general formula (III) can be obtained by condensation reaction of ethylene urea and formalin, and by reacting this product with a lower alcohol.
Specific examples of such ethylene urea crosslinking agents include, for example, mono and / or dihydroxymethyl ethylene urea, mono and / or dimethoxymethylated ethylene urea, mono and / or diethoxymethylated ethylene urea, mono and / or dipropoxymethyl Ethylene urea, mono- and / or dibutoxymethylated ethylene urea, 1,3-di (methoxymethyl) 4,5-dihydroxy-2-imidazolidinone, 1,3-di (methoxymethyl) -4,5- And dimethoxy-2-imidazolidinone.

Specific examples of the glycoluril-based crosslinking agent include glycoluril derivatives in which the N position is substituted with one or both of a hydroxyalkyl group and an alkoxyalkyl group having 1 to 4 carbon atoms.
Such a glycoluril derivative can be obtained by a condensation reaction between glycoluril and formalin and by reacting this product with a lower alcohol.
Examples of the glycoluril-based crosslinking agent include mono, di, tri and / or tetrahydroxymethyl glycoluril, mono, di, tri and / or tetramethoxymethylated glycoluril, mono, di, tri and / or tetraethoxymethyl glycol. Examples include uril, mono, di, tri and / or tetrapropoxymethylated glycoluril, mono, di, tri and / or tetrabutoxymethylated glycoluril.

  The content of the component (C) in the negative resist composition of the present invention is preferably 3 to 50 parts by mass, more preferably 10 to 20 parts by mass per 100 parts by mass of the component (A). When the content of the component (C) is less than this range, crosslinking formation does not proceed sufficiently and a good resist pattern cannot be obtained. On the other hand, if it exceeds this range, the storage stability and sensitivity of the resist coating solution may deteriorate over time.

Organic solvent The negative resist composition of the present invention is obtained by dissolving the above-described component (A), component (B), component (C), component (D), and any of the components described later in an organic solvent. Can be manufactured.
Any organic solvent may be used as long as it can dissolve each component to be used to form a uniform solution, and one or two kinds of conventionally known solvents for chemically amplified resists can be used. These can be appropriately selected and used.
For example, ketones such as γ-butyrolactone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol Or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and other polyhydric alcohols and derivatives thereof, cyclic ethers such as dioxane, methyl lactate, lactic acid Ethyl (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxy Methyl propionate, esters such as ethyl ethoxypropionate can be exemplified.
These organic solvents may be used individually by 1 type, and may be used as a 2 or more types of mixed solvent.

Among these, it is preferable to use at least one selected from propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and ethyl lactate (EL).
Further, a mixed solvent in which propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent are mixed is preferable, but the blending ratio may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably It is preferable to be within a range of 1: 9 to 8: 2, more preferably 2: 8 to 5: 5.
More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 2: 8 to 5: 5, more preferably 3: 7 to 4: 6.
In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.
Although the amount of the organic solvent used is not particularly limited, it is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film thickness. In general, the solid content concentration of the resist composition is 2 to 20 mass. %, Preferably in the range of 5 to 15% by mass.

Nitrogen-containing organic compound (E) (hereinafter sometimes referred to as component (E))
In the negative resist composition of the present invention, a nitrogen-containing organic compound (E) (hereinafter referred to as (E) component) is further added as an optional component in order to improve the resist pattern shape, stability over time and the like. Can be blended.
A wide variety of components (E) have already been proposed, and any known one may be used, but amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred.
Specific examples of the component (E) include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, tri-n-heptylamine, tri-n-octylamine, di- alkylamines such as n-heptylamine, di-n-octylamine, tri-n-dodecylamine, diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, tri-n-octanolamine And amines of alkyl alcohols such as Of these, secondary or tertiary aliphatic amines having an alkyl group having 7 to 15 carbon atoms are preferred. By having an alkyl group having 7 to 15 carbon atoms, the aliphatic amine can be evenly distributed because it is difficult to diffuse in the formed resist pattern. In the present invention, alkylamines such as tri-n-octylamine and tri-n-dodecylamine are particularly preferable.
These may be used alone or in combination of two or more.
(E) A component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

Acid component (F) (hereinafter sometimes referred to as component (F))
An acid comprising an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof as an optional component for the purpose of preventing sensitivity deterioration due to the blending with the component (E) and improving the resist pattern shape, retention stability and the like. A component (F) (henceforth (F) component) can be contained. In addition, (E) component and (F) component can also be used together, and any 1 type can also be used.

As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
Component (F) is used in a proportion of 0.01 to 5.0 parts by mass per 100 parts by mass of component (A).

<Other optional components>
The negative resist composition of the present invention further contains miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, plasticizers, and stability. A coloring agent, a coloring agent, an antihalation agent, and the like can be appropriately added and contained.

<Method for forming resist pattern>
The negative resist composition of the present invention is applied to, for example, a resist pattern forming method using a conventional photoresist technique.
Specifically, first, the negative resist composition of the present invention prepared in the form of a solution is applied on a substrate with a spinner or the like and dried to form a negative resist film.
The substrate is not particularly limited, and may be any of various substrates to which a negative resist is conventionally applied, such as a silicon wafer, a silicon wafer provided with an organic or inorganic antireflection film, and a glass substrate.

Next, an exposure process is selectively performed on the negative resist film. For the exposure process, KrF excimer laser light, ArF excimer laser light, F ₂ excimer laser light, EUV (Extreme ultraviolet extreme ultraviolet light), electron beam, soft X-ray, X-ray, etc. can be used. Irradiation through or direct drawing.
Subsequently, post-exposure heat treatment (post-exposure baking, hereinafter sometimes referred to as PEB) is performed. The heating conditions in the PEB treatment vary depending on the type of each component in the resist composition, the blending ratio, the coating film thickness, and the like, but are, for example, about 80 to 150 ° C. and 40 to 120 seconds, more preferably about 60 to 90 seconds.

After the PEB treatment, a negative resist pattern can be obtained by developing with a developer such as an alkaline aqueous solution, and performing treatment as necessary, such as washing with water and drying.
The developer is not particularly limited, and a commonly used alkaline aqueous solution or the like can be used. For example, an aqueous solution of TMAH (tetramethylammonium hydroxide) having a concentration of 2.38% by mass is preferably used.

[Example 1]
<Preparation of negative resist composition>
A negative photoresist composition by uniformly dissolving the following components (A), (B), (C), (D), (E), (F) and other components in an organic solvent. Was prepared.
As component (A), 100 mass% of a copolymer having a dispersity of 1.3 consisting of 78.5 mol% of structural units derived from p-hydroxystyrene and 21.5 mol% of structural units derived from styrene. Used. The mass average molecular weight of this (A) component was 2500.
As the component (B), 8.0 parts by mass of α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile was used.
As the component (C), 3.0 parts by mass of bismethoxymethyl urea (product name: N-8314, manufactured by Sanwa Chemical Co., Ltd.) and hexamethoxymethylmelamine (product name: Mw30HM, manufactured by Sanwa Chemical Co., Ltd.) Combined with 3.0 parts by weight.
As the component (D), 3.0 parts by mass of α, α′-dihydroxy-1,3-diisopropylbenzene represented by the following chemical formula (2) was used.
As component (E), 0.69 parts by mass of trioctylamine was used.
As component (F), 0.23 parts by mass of salicylic acid was used.
As other components, 0.12 parts by mass of a fluorosurfactant (product name XR-104, manufactured by Dainippon Ink & Chemicals, Inc.) was used.
The above components were dissolved in 1900 parts by mass of propylene glycol monomethyl ether (PGME) as an organic solvent to obtain a negative resist composition.

By applying the negative resist composition prepared above on a silicon wafer surface-modified with HMDS (hexamethyldisilazane) in advance with a spinner and pre-baking at 110 ° C. for 90 seconds, the thickness is increased. A resist film having a thickness of 200 nm was formed.
Subsequently, drawing was performed using an electron beam drawing apparatus (product name: HL-800D, 70 kV acceleration voltage, manufactured by Hitachi, Ltd.).
Subsequently, after PEB treatment was performed at 110 ° C. for 90 seconds, TMAH having a concentration of 2.38% by mass was dropped on the substrate as a developer, developed for 60 seconds, and then rinsed with pure water. Then, it was shaken and dried. Further, a heat treatment (post-bake) was performed at 100 ° C. for 60 seconds to form an isolated line pattern of 80 nm. The obtained resist pattern was observed with a scanning electron microscope (SEM).

The limit resolution of the isolated line pattern was 60 nm.
In addition, the line width of an isolated line pattern with a line width of 80 nm obtained at the optimum exposure (Eop) was measured at five locations in the line direction with a side length SEM (trade name: S-9220, manufactured by Hitachi, Ltd.) From the result, a triple value (3 s) of the standard deviation (s) was calculated as a scale indicating LWR. The smaller the value of 3s, the smaller the roughness of the line width, which means that a resist pattern with a more uniform width was obtained. The value of 3s in this example was 7.2 nm.

[Comparative Example 1]
In Example 1, the isolated line pattern was formed in the same manner except that the component (D) was not added.
The obtained resist pattern was evaluated in the same manner as in Example 1. The limit resolution of the isolated line pattern was 60 nm. The value of 3s indicating LWR was 8.4 nm.

[Comparative Example 2]
In Example 1 above, the blending amount of trioctylamine as component (E) was changed to 0.46 parts by mass, the blending amount of salicylic acid as component (F) was changed to 0.15 parts by mass, and ( An isolated line pattern was formed in the same manner except that component D) was not added.
The obtained resist pattern was evaluated in the same manner as in Example 1. The limit resolution of the isolated line pattern was 60 nm. The value of 3s indicating LWR was 11.5 nm.

From the results of Example 1 and Comparative Examples 1 and 2, it was found that there was no difference in resolution and sensitivity, but LWR was reduced by adding component (D).

Claims (3)

In a negative resist composition containing an alkali-soluble resin (A), an acid generator (B) that generates an acid upon irradiation with radiation, and a crosslinking agent (C),
The component (A) is represented by the following general formula (I)

(In the formula, R represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 3.)
(A1) unit represented by the following general formula (II)

(In the formula, R represents a hydrogen atom or a methyl group, R ₁ represents an alkyl group having 1 to 5 carbon atoms, and n represents 0 or an integer of 1 to 3).
A copolymer having a unit (a2) represented by:
The component (B) is an oxime sulfonate acid generator,
The component (C) is a mixture of a melamine crosslinking agent and a urea crosslinking agent,
Furthermore, tri-n-octylamine or tri-n-dodecylamine and the following general formula (1)

(In the formula, R ′ and R ″ each independently represents an alkyl group having 1 to 5 carbon atoms. P is 2 or 3.)
A negative resist composition comprising a compound (D) represented by the formula:   The negative resist composition according to claim 1, wherein p in the general formula (1) is 2. On the substrate, after using a negative resist composition according to claim 1 or 2 to form a negative resist film was subjected to selective exposure to said negative resist film, heat treatment (post A resist pattern forming method characterized in that a resist pattern is formed by performing an exposure bake) and then performing a development process.