JP3496916B2 - Negative resist composition for electron beam - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is suitable for electron beams.
Suitable novel negative resist composition, more particularly, gamma
The present invention relates to a negative resist composition for electron beams, which has a high value, that is, has good contrast and resolution, has high sensitivity, and gives a resist pattern having an excellent shape.

[0002]

2. Description of the Related Art Conventionally, halogen acid-based acid generators such as triazine compounds having a trichloromethyl group and tris (2,3-dibromopropyl) isocyanurate have been used as acid generators in negative resists for electron beams . Came. However, in the future, when manufacturing ultra-high integration semiconductor devices such as 256 mega, 1 giga and 4 giga,
A conventional resist using a halogen acid-based acid generator has insufficient crosslinking efficiency in the exposed area, and the sensitivity, resolution and resist pattern shape are no longer satisfactory. As described above, in electron beam resists, which are promising for the production of ultra-high integrated circuits, improvements in sensitivity, resolution, and resist pattern shape are desired.

On the other hand, it has been proposed to use an oxime sulfonate compound as an acid generator for a chemically amplified resist (Japanese Patent Laid-Open No. 1-124848 and Japanese Patent Laid-Open No. 2-4848).
Japanese Patent No. 154266, Japanese Patent Laid-Open No. 2-161444,
JP-A-6-17433). Among these, as oxime sulfonate compounds having a cyano group, for example, α- (p-toluenesulfonyloxyimino) -benzylcyanide and α- (p-chlorobenzenesulfonyloxyimino) -benzylcyanide are disclosed. .
However, these oxime sulfonate compounds having a cyano group, when used as an acid generator of a negative resist for electron beam for the production of ultra-high integrated circuits, show contrast, γ value, resolution, sensitivity and resist pattern shape. Not everything is well-balanced and satisfying. The above-mentioned γ value is a value calculated from a sensitivity curve showing a relationship between the exposure amount and the residual film ratio (developing with respect to resist coating film thickness, resist film thickness after exposure) using a predetermined calculation formula. , The factor of contrast and resolution.

[0004]

Under the circumstances, the present invention provides a resist pattern having a high γ value, that is, good contrast and resolution and high sensitivity, and an excellent shape. It was made for the purpose of providing a negative resist composition for electron beams to be given.

[0005]

The inventors of the present invention have conducted extensive studies to develop a negative resist composition for electron beam having the above-mentioned preferable properties, and as a result, have developed a specific alkali-soluble resin and a specific acid generation. It was found that the object can be achieved by combining an agent with a specific acid-crosslinking substance, and the present invention has been completed based on this finding.

That is, the present invention comprises (A) an alkali-soluble resin, (B) an acid generator, and (C) an acid crosslinkable substance.
In the negative resist composition containing the component (A),
And a resin having a molecular weight distribution (Mw / Mn) of 3.5 or less,
(A ) General formula as the component (B)

[Chemical 3] (Wherein R ¹ is an aromatic hydrocarbon group, R ² is a lower alkyl group or a lower halogenated alkyl group) and (b) the general formula

[Chemical 4] (Wherein X is a divalent aromatic hydrocarbon group and R ³ is a lower alkyl group or a lower halogenated alkyl group), at least one selected from the group (C) As a component, hydroxyl group or
The present invention provides a negative resist composition for electron beam, which is characterized by using an amino resin having a rucoxyl group .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the composition of the present invention, the alkali-soluble resin used as the component (A) is not particularly limited, and those conventionally used in negative resist compositions for electron beams can be used. it can. Examples of such an alkali-soluble resin include novolak resins obtained by condensing phenols such as phenol, m-cresol, p-cresol, xylenol, and trimethylphenol with aldehydes such as formaldehyde under an acidic catalyst, and hydroxystyrene. , A homopolymer of hydroxystyrene and a copolymer of hydroxystyrene with another styrene monomer, a polyhydroxystyrene resin such as a copolymer of hydroxystyrene and acrylic acid or methacrylic acid or a derivative thereof, acrylic acid or methacrylic acid Examples thereof include an alkali-soluble resin such as acrylic acid or methacrylic acid-based resin which is a copolymer of carboxylic acid and a derivative thereof, and a resin in which a part of hydroxyl groups of polyhydroxystyrene is protected by an acid dissociable substituent.

Examples of the styrene-based monomer copolymerized with the above-mentioned hydroxystyrene include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene and p-
Methoxystyrene, p-chlorostyrene and the like can be mentioned. Examples of the acrylic acid or methacrylic acid derivatives include methyl acrylate, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylamide, acrylonitrile and corresponding methacrylic acid derivatives.

On the other hand, examples of the acid dissociable substituent include tertiary alkyloxycarbonyl groups such as tert-butoxycarbonyl group and tert-amyloxycarbonyl group, and tertiary alkyloxy groups such as tert-butoxycarbonylmethyl group. Carbonylalkyl group, tert
-A tertiary alkyl group such as a butyl group, an alkoxyalkyl group such as an ethoxyethyl group and a methoxypropyl group,
An acetal group such as a tetrahydropyranyl group and a tetrahydrofuranyl group, a benzyl group, a trimethylsilyl group and the like can be mentioned. The rate of protection of hydroxyl groups by these acid-dissociable substituents is usually in the range of 1 to 60 mol%, preferably 10 to 50 mol% of the hydroxyl groups in the resin.

As these alkali-soluble resins , resins having a molecular weight distribution (Mw / Mn ratio) of 3.5 or less are used.
It These are easily available as commercial products
However , in the case of a novolac resin having an Mw / Mn ratio of more than 3.5, the low-molecular weight portion may be removed by a known fractional precipitation treatment so that the Mw / Mn ratio is 3.5 or less.

[0011] As the component (A) definitive to the present invention,
Polyhydroxystyrene, polyhydroxystyrene having a hydroxyl group protected by an acid dissociative substituent, a copolymer of hydroxystyrene and styrene, and a cresol novolac resin are preferable, and particularly, a molecular weight distribution (Mw / Mn ratio)
M-cresol novolac resin of 3.5 or less, polyhydroxystyrene having a molecular weight distribution (Mw / Mn ratio) of 1.5 or less, a copolymer of hydroxystyrene and styrene, and a part of hydroxyl groups of polyhydroxystyrene is tert-butoxycarbonyl. A resin protected with a group is preferred. In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are the gel permeation chromatography method (GPC method).
It is a value in terms of polystyrene measured by.

In the present invention, the alkali-soluble resin as the component (A) may be used alone or in combination of two or more kinds. In the composition of the present invention, the oxime sulfonate compound represented by the general formula (I) or the general formula (I) is used as the acid generator as the component (B).
Using an oxime sulfonate compound represented by I)
Is necessary .

Examples of the aromatic hydrocarbon group represented by R ¹ in the above general formula (I) include phenyl group and naphthyl group, while the lower alkyl group of R ² has 1 carbon atom. 4 straight-chain or branched alkyl groups, specifically methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s
an ec-butyl group, a tert-butyl group, etc.
The lower halogenated alkyl group of ^2, halogenated lower alkyl group having 1 to 4 carbon atoms, specifically chloromethyl group, trichloromethyl group, trifluoromethyl group, and 2-bromopropyl group .

Examples of the oxime sulfonate compound represented by the general formula (I) include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -4-methoxyphenylacetonitrile, α- ( Trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -4-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -4-methoxyphenylacetonitrile,
Examples include α- (propylsulfonyloxyimino) -4-methylphenylacetonitrile and α- (methylsulfonyloxyimino) -4-bromophenylacetonitrile. Among these, those in which R ² is a lower alkyl group such as a methyl group or an ethyl group have high crosslinking efficiency,
In addition, it has high sensitivity and high resolution, and the resist pattern shape is rectangular, which is preferable.

On the other hand, in the general formula (II), R ³
Examples of the lower alkyl group include a methyl group,
Examples thereof include an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group.

On the other hand, the lower halogenated alkyl group of R ³ is, for example, a halomethyl group having 1 to 4 carbon atoms such as chloromethyl group, trichloromethyl group, trifluoromethyl group and 2-bromopropyl group. Can be mentioned. Further, X of the oxime sulfonate compound represented by the general formula (II) is a divalent aromatic hydrocarbon group such as a phenylene group .

Examples of the oxime sulfonate compound represented by the general formula (II) are shown below.

[0018]

[Chemical 5]

[0019]

[Chemical 6]

In the present invention, the oxime sulfonate compound as the component (B) may be used alone or in combination of two or more kinds. Further, if necessary, it can be used in combination with a known acid generator which is commonly used in conventional resist compositions.

[0021] In the present invention the composition, the (C) for the acid-crosslinkable substance used as component, acid-crosslinkable material that is conventionally used as a crosslinking agent in the negative resist for conventional electron beam, i.e. a hydroxyl group or an alkoxyl group Amino resin having , for example, melamine resin, urea resin,
Guanamine resin, glycoluril-formaldehyde resin, succinylamide-formaldehyde resin, ethylene urea-formaldehyde resin and the like are used . Amines having these hydroxyl groups or alkoxyl groups
Resins include amino acids such as melamine, urea, guanamine, glycoluril, succinylamide, ethylene urea.
It can be easily obtained by reacting a resin with formalin in boiling water to form a methylol, or by further reacting this with a lower alcohol to alkoxylate. Among these, a melamine resin and a urea resin having a hydroxyl group or an alkoxyl group are particularly preferable. Such a product is, for example, Nikarac Mx-750, Nikarac M.
w-30, Nikarac Mw-30HM, Nikarac Mw
-100LM and Nikarac Mx-290 (both manufactured by Sanwa Chemical Co., Ltd.) are available.

[0022] It These acid-crosslinkable material may be used singly or may be used in combination of two or more.

Regarding the blending ratio of each component in the composition of the present invention, it is advantageous to use the component (B) in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the component (A). If the amount of the component (B) is less than 0.1 parts by weight, image formation is insufficient, and if it exceeds 30 parts by weight, it is difficult to form a uniform resist film and the developability is lowered, and a good resist pattern is obtained. Is difficult to obtain. From the viewpoint of the balance of image forming property, resist film forming property and developing property, the component (B) is contained in an amount of 1 to 2 with respect to 100 parts by weight of the component (A).
It is particularly preferred to use 0 part by weight. Also,
The component (C) is 3 to 7 relative to 100 parts by weight of the component (A).
Preference is given to using 0 parts by weight. If the amount of this component (C) is less than 3 parts by weight, the sensitivity is insufficient, and 70
If it exceeds the weight part, it is difficult to form a uniform resist film, and the developability also deteriorates, and it becomes difficult to obtain a good resist pattern. From the viewpoint of the balance of sensitivity, resist film forming property, developability and the like, it is particularly preferable to use the component (C) in an amount of 10 to 50 parts by weight based on 100 parts by weight of the component (A).

In the composition of the present invention, various amines such as ethylamine, diethylamine, triethylamine, n-propylamine, di-n are added, if necessary, in order to improve the resist pattern shape, the stability with time of leaving and the like. -Aliphatic amines such as propylamine and tri-n-propylamine, aromatic amines such as benzylamine, aniline, N-methylaniline and N, N-dimethylaniline, pyridine, 2-methylpyridine, 2-ethylpyridine, Heterocyclic amines such as 2,3-dimethylpyridine can be added. Among these, triethylamine is particularly preferable because it gives a resist composition having excellent resist pattern shape and leaving stability over time.

If necessary, butyric acid, isobutyric acid, oxalic acid, malonic acid, succinic acid, acrylic acid, crotonic acid, isocrotonic acid, 3-butenoic acid, methacrylic acid, 4
-Saturated or unsaturated aliphatic carboxylic acids such as pentenoic acid,
1,1-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,1
-Cyclohexyldiacetic acid and other alicyclic carboxylic acids, p-hydroxybenzoic acid, o-hydroxybenzoic acid, 2-hydroxy-3-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 2-nitrobenzoic acid, 2,4 -Dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5
-Dihydroxybenzoic acid, 2-vinylbenzoic acid, 4-vinylbenzoic acid, phthalic acid, terephthalic acid, isophthalic acid and other hydroxyl groups, nitro groups, carboxyl groups, vinyl groups and other aromatic carboxylic acids and other carboxylic acids, etc. Acids can be added.

Of these carboxylic acids, aromatic carboxylic acids are preferred because they have a suitable acidity. Of these, salicylic acid is preferable because it is soluble in a resist solvent and a good resist pattern can be obtained on various substrates.

Regarding the addition amount of the amines and carboxylic acids, the amines are 0.01 to 1% by weight, preferably 0.02% with respect to the component (A) in view of the resist pattern shape and sensitivity. Is preferably in the range of 0.01 to 1.0% by weight, preferably 0.02 to 1% by weight, based on the total amount of the components (A) and (C). A range of 0.0% by weight is advantageous.

The composition of the present invention is preferably used in the form of a solution in which the above components are dissolved in a solvent. Examples of such a solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone: ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, diketone. Polyhydric alcohols such as propylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and their derivatives: cyclic ethers such as dioxane: and methyl lactate, lactic acid Ethyl, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate It can be mentioned esters such as ethyl ethoxypropionate. These may be used alone or in combination of two or more.

The composition of the present invention may further contain conventional additives which are miscible, such as additional resins, plasticizers, stabilizers, colorants and surfactants for improving the performance of the resist film. Can be included.

To form a resist pattern using the composition of the present invention, a solution of the resist composition is applied on a support such as a silicon wafer by a spinner or the like and dried to form a photosensitive layer. , Draw with an electron beam and heat. This is then developed with a developer, eg 1-10
Development is performed using an alkaline aqueous solution such as a wt% tetramethylammonium hydroxide aqueous solution. In this way, a resist pattern having an excellent profile shape can be obtained with high resolution.

[0031]

INDUSTRIAL APPLICABILITY The negative resist composition for electron beams of the present invention has a high γ value, that is, has good contrast and resolution, and has high sensitivity, and can give a resist pattern having an excellent shape. Particularly, it is preferably used for manufacturing a semiconductor device having an extremely high degree of integration.

[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.

Example 1 Weight average molecular weight 2500, molecular weight distribution (Mw / Mn)
100 parts by weight of a copolymer of 85 mol% hydroxystyrene and 15 mol% styrene of 1.5, 15 parts by weight of melamine resin Nicalac Mw-30HM (manufactured by Sanwa Chemical Co., Ltd.), 0.5 parts by weight of triethylamine and salicylic acid. 0.5 parts by weight was dissolved in 250 parts by weight of propylene glycol monomethyl ether acetate, and 8 parts by weight of α- (methylsulfonyloxyimino) -phenylacetonitrile was dissolved therein to prepare a negative resist solution for electron beam.

Next, this resist solution is applied onto a silicon wafer using a spinner and dried on a hot plate at 120 ° C. for 90 seconds to obtain a film thickness of 0.7.
A μm resist layer was formed. Then, after irradiating an electron beam with an electron beam irradiation device HL-750D (manufactured by Hitachi, Ltd.), heat treatment was performed at 120 ° C. for 90 seconds, and then development was performed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 65 seconds. It was washed with water for 30 seconds and dried.
At this time, the minimum exposure time at which an image is formed on the exposed portion after development was measured as a sensitivity in μC / cm ² (energy amount), and it was 6.0 μC / cm ² . The limiting resolution of the resist pattern obtained by such a method was 0.14 μm. Furthermore, the cross-sectional shape of the 0.20 μm resist pattern thus formed is S
When observed by EM (scanning electron microscope) photograph,
It was a rectangular resist pattern perpendicular to the substrate.

Example 2 In Example 1, instead of α- (methylsulfonyloxyimino) -phenylacetonitrile,

[Chemical 7] A negative resist solution for electron beam was prepared in the same manner as in Example 1 except that the compound shown in 1 was used. Then, when the physical properties were measured in the same manner as in Example 1, the sensitivity was 10
μC / cm ² , the limiting resolution was 0.14 μm. Further, when the cross-sectional shape of the formed 0.20 μm resist pattern was observed by an SEM (scanning electron microscope) photograph, it was a rectangular resist pattern perpendicular to the substrate.

Example 3 In Example 1, instead of α- (methylsulfonyloxyimino) -phenylacetonitrile,

[Chemical 8] A negative resist solution for electron beam was prepared in the same manner as in Example 1 except that the compound shown in 1 was used. Then, when the physical properties were measured in the same manner as in Example 1, the sensitivity was 12
μC / cm ² , the limiting resolution was 0.14 μm. Further, when the cross-sectional shape of the formed 0.20 μm resist pattern was observed by an SEM (scanning electron microscope) photograph, it was a rectangular resist pattern perpendicular to the substrate.

Comparative Example 1 Tris (2,3-dibromopropyl) incyanurate 1 was used in place of 8 parts by weight of α- (methylsulfonyloxyimino) -phenylacetonitrile in Example 1.
A negative resist solution for electron beam was prepared in the same manner as in Example 1 except that 0 part by weight was used. Then, the physical properties were measured as in Example 1. The sensitivity was 15 μC / c.
m ² , the limiting resolution was 0.18 μm. In addition, the cross-sectional shape of the formed 0.20 μm resist pattern is S
When observed by EM (scanning electron microscope) photograph,
It was a tapered resist pattern.

Comparative Example 2 In Example 1, instead of α- (methylsulfonyloxyimino) -phenylacetonitrile, 2- (4-
A negative resist solution for electron beam was prepared in the same manner as in Example 1 except that methoxyphenyl) -4,6- (bistrichloromethyl) -1,3,5-triazine was used. Then, the physical properties were measured in the same manner as in Example 1. The sensitivity was 6.0 μC / cm ² , and the limiting resolution was 0.30.
was μm. Further, when the cross-sectional shape of the formed 0.30 μm resist pattern was observed by a SEM (scanning electron microscope) photograph, it was a tapered resist pattern.

Comparative Example 3 In Example 1, instead of α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (p-
A negative resist solution for electron beam was prepared in the same manner as in Example 1 except that toluenesulfonyloxyimino) -4-methoxyphenylacetonitrile was used. Then, the physical properties were measured in the same manner as in Example 1, and the sensitivity was 1
The limit resolution was ² μC / cm ² and 0.20 μm.
Further, when the cross-sectional shape of the formed 0.20 μm resist pattern was observed by an SEM (scanning electron microscope) photograph, it was a tapered resist pattern.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Yamazaki 150 Nakamaruko, Nakahara-ku, Kawasaki, Kanagawa Tokyo Ohka Kogyo Co., Ltd. (72) Yoshiki Sugata, 150 Nakamaruko, Nakahara-ku, Kawasaki, Kanagawa Tokyo Ohka Kogyo Co., Ltd. (72) Inventor Hiroshi Komano 150 Nakamaruko, Nakahara-ku, Kawasaki-shi, Kanagawa Tokyo Ohka Kogyo Co., Ltd. (56) Reference JP-A-2-154266 (JP, A) JP-A-2-161444 (JP, A) JP-A-9-211846 (JP, A) JP-A-10-90901 (JP, A) JP-A-10-171109 (JP, A) JP-A-10-186660 (JP, A) JP-A-10-186661 (JP, A) JP 60-65072 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (4)

(57) [Claims] 1. An (A) alkali-soluble resin, and (B)acid
Negative cash register containing generator and (C) acid crosslinkable substance
In the strike composition, the molecular weight distribution (M
w / Mn) 3.5 or less resin as the component (B)
(A) General formula [Chemical 1] (R in the formula¹Is an aromatic hydrocarbon group, R²Is a lower alkyl group
Or a lower halogenated alkyl group) and (b) in general
formula [Chemical 2] (X in the formula is a divalent aromatic hydrocarbon group, R³Is lower al
A alkyl group or a lower halogenated alkyl group)
Selected from among oxime sulfonate compounds
At least oneAs a component (C) is a hydroxyl group or an
Using an amino resin having a rucoxyl groupCharacterized by
Electron beamforNegative resist composition. Wherein R ¹ in the general formula of (a) is phenylene
2. A negative resist composition for electron beam according to claim 1, wherein the negative resist composition is a vinyl group.
object. 3. X in the general formula (b) is a phenylene group.
The negative resist composition for electron beam according to claim 1. 4. The (A) component alkali-soluble resin is selected from polyhydroxystyrene, polyhydroxystyrene having a hydroxyl group protected by an acid-labile substituent, a copolymer of hydroxystyrene and styrene, and a cresol novolac resin. It is at least 1 type selected, 1 , 2 or
Is a negative resist composition for electron beam according to 3 .