JPH04158362A - Radioactive-ray-sensitive resin composition material - Google Patents

Abstract

PURPOSE:To effectively suppress the absorption and reaction of a silicon compound at a radiation section by allowing the acid generated when radioactive rays are radiated to act on an acid cross linking agent by heat treatment after radioactive rays are radiated and strengthen the cross linking of resist. CONSTITUTION:Radioactive rays, e.g., ultraviolet rays, far ultraviolet rays, X-rays, electron rays and visible rays, are radiated to a resist layer on a substrate through a pattern. Acid is generated from the component at a radiation section by the radiation of the radioactive rays. A substrate provided with the resist layer is heat-treated. The material of the component is reacted with resin by this heating to form a cross linking structure on polymer molecules of this resin. A silicon compound is infiltrated and diffused in a nonradiation section, the infiltration of the silicon compound into the radiation section is firmly suppressed, and an etching-resistive positive latent image is formed. It is developed by dry developing, then a desired positive pattern is obtained. The absorption and reaction of the silicon compound can be effectively suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radiation-sensitive resin composition, and more particularly to a radiation-sensitive resin composition that can be used as a resist suitable for dry development by plasma etching. .

[Conventional technology] Conventionally, in the manufacturing process of semiconductor devices such as ICs and LSIs,
A radiation-sensitive resin composition such as a negative photoresist made by mixing a polyisoprene cyclized product with bisazide or a positive photoresist made by mixing a novolac resin with a quinone diazide compound is applied onto the substrate to be processed, and the
A photolithography method is employed in which a pattern is formed by exposing to light using a line (wavelength: 436 nm) or i-line (365 nm) and developing with a developer.

However, in recent years, LSIs have become even more miniaturized, and the minimum dimension of a pattern to be formed on a substrate is entering the region of 1 μm or less. Even if it is used, especially when a substrate with a stepped structure is used, problems such as the influence of light reflection during exposure and the shallow depth of focus in the exposure system cause problems such as insufficient resolution. .

As a method to solve such problems, a method is known in which a resist pattern is formed by etching and developing using gas plasma such as oxygen plasma instead of developing using a developer in the photolithography method. .

JP-A No. 61-107346 discloses that a photosensitive resin layer containing a polymer mixed or combined with a photoactive compound is applied to a substrate, and the irradiated portion of the core layer is exposed to visible light or ultraviolet light. When exposed to light, the silicon compound has the property of selectively diffusing into the irradiated portion; the photosensitive resin layer is exposed to ultraviolet light through a mask that exposes only the selected portion of the core layer. or exposing to visible light; treating said photosensitive resin layer with a silicon compound, thereby causing said silicon compound to be selectively absorbed into the irradiated portions of said photosensitive resin layer, thereby exposing said photosensitive resin layer to said irradiated portions; The photosensitive resin layer treated in this way is then dry developed by plasma etching to selectively remove the non-irradiated areas.
A method for obtaining desired negative figures is described.

This JP-A-61-107346 discloses that the photosensitive resin layer is specifically made of a phenolic polymer and diazoquinone (a photoactive compound), but in this photosensitive resin layer, As described above, only a negative pattern can be formed in which the exposed portion remains as a resist pattern.

Furthermore, Japanese Patent Application Laid-Open No. 61-284924 discloses (a) depositing a layer of a polymer-resist material on a substrate; (b) depositing the polymer-resist material on the layer of the polymer-resist material;
applying in a pattern at least one type of radiation capable of altering the permeability of the resist material; (c) applying an organometallic material to the surface of the layer of polymeric resist material; A method of forming an etch-resistant coating is disclosed that selectively infiltrates according to the pattern described above. According to this method, both positive and negative patterns can be formed.

That is, the examples include m-cresol formaldehyde novolac resin and 2-diazonaphthoquinone-
A thin layer of a mixture of 5-sulfonic acids (polymer resist material) on a substrate is irradiated with deep ultraviolet light (220-280 nm) through a pattern to form crosslinks in the exposed areas and treated with hexamethylcyclotrisilazane to form a non-conductive layer. Discloses a method of penetrating and diffusing the novolak resin into an exposed area to react so as to replace the phenol hydroxyl groups of the novolac resin with groups containing silicon, forming an etching-resistant positive latent image, and dry developing to form a positive pattern. In another embodiment, a thin layer of the same polymeric resist material as described above is exposed to near ultraviolet light (350-
450 nm) through the pattern to cause photofragmentation in the exposed areas, treated with hexamethylcyclotrisilazane to diffuse into the exposed areas to form an etch-resistant negative latent image, and dry developed. A method of forming a negative pattern is disclosed.

However, in any of the above methods, there are problems such as low resolution or residue remaining between fine patterns after dry development because the difference in penetration of the silicon compound between exposed and unexposed areas is not sufficient. I can't deny it.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a radiation-sensitive resin composition for positive dry development having a novel composition.

Another object of the present invention is to provide a positive type dry developing texture in which the degree of crosslinking is strong in the radiation irradiated area, and therefore the absorption and reaction of silicon compounds in the radiation irradiated area can be suppressed much more effectively than in the non-irradiated area. An object of the present invention is to provide a radioactive resin composition.

Still another object of the present invention is to provide a positive-type radiation-sensitive resin composition for dry development which can provide highly accurate positive-type etched images with high resolution and high selectivity with good reproducibility.

Further objects and advantages of the invention will become apparent from the description below.

[Means for Solving the Problems] According to the present invention, the above objects and advantages of the present invention are achieved by: (a) a resin having a phenolic hydroxyl group; (b) a substance that generates an acid upon irradiation with radiation; ) A substance that reacts with the resin (a) under the action of acid and heat to form a crosslinked structure between the polymer molecular chains of the resin (a). This is achieved by a resin composition.

The resin composition of the present invention has (a) and (b) as described above.
Contains the following three components: and (iii).

Among these, resins having phenolic hydroxyl groups (a)
Preferred examples include novolac resins having hydroxyl groups, hydroxyxystyrene resins, and the like.

Among these, novolak resin is synthesized by condensing a hydroxy aromatic compound and an aldehyde under an acid catalyst.

Examples of the hydroxy aromatic compound include 1-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol, 4-ethoxy-1-naphthol,
-Propoxy-1-naphthol, 4-butoxy-1-naphthol, 5-methyl-1-naphthol, 2-ethyl-
1-naphthol, 2-propyl-1-naphthol, 2-
Hydroxynaphthalenes such as butyl-1-naphthol; e.g. phenol, cresol, ethylphenol,
Examples include alkylphenols such as butylphenol, and phenols such as xylenol, trimethylphenol, and phenylphenol.

These hydroxy aromatic compounds can be used alone or in combination.

Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α
-Phenylpropylaldehyde, β-phenylpropylaldehyde, 0-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, 0-
Examples include methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, p-n-butylbenzaldehyde, and the like.

When producing a novolac resin, the above-mentioned aldehyde is preferably used in a ratio of 0.7 to 3 mol, more preferably 1.1 to 2 mol, per 1 mol of the hydroxy aromatic compound.

Preferred acid catalysts used in this case include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as formic acid, oxalic acid, and acetic acid.

The amount of these acid catalysts used is 1X10-4 to 1 mole of the total amount of hydroxyaromatic compound and aldehyde used.
Preferably, it is 5xlO-1 mol.

In the condensation reaction, water is usually used as the reaction medium, but if the hydroxy aromatic compound used in the condensation reaction does not dissolve in the aqueous aldehyde solution and the reaction becomes a heterogeneous system from the early stage, water may be used as the reaction medium. A hydrophilic solvent can be used alone or in combination with water to improve the solubility of the hydroxyaromatic compound in the reaction system.

Examples of such hydrophilic solvents include alcohols such as methanol, ethanol, propatool, and butanol;
Examples include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and cyclic ethers such as tetrahydrofuran and dioxane.

The amount of these reaction media used is preferably 10
The amount is 50 to 1.000 parts by weight per 0 parts by weight.

The reaction temperature during the condensation reaction can be adjusted as appropriate depending on the reactivity of the reaction raw materials, but is preferably 10 to 150°C.
and more preferably 70 to 130°C.

Unreacted monomers present in the system following the condensation reaction,
Internal temperature 1 to remove aldehyde, acid catalyst and reaction medium
It is advantageous to raise the temperature to 30 DEG to 230 DEG C. and distill off the volatile components under reduced pressure to recover the desired novolak resin.

Further, after the condensation reaction is completed, the reaction mixture is dissolved in the hydrophilic solvent, and a precipitating agent such as water, n-hexane, or n-heptane is added to precipitate the novolac resin,
The novolak resin can also be recovered by separating the precipitate and drying it by heating.

The polystyrene equivalent weight average molecular weight of these novolac resins is preferably 200 to 200,000, more preferably 500 to 10
0,000. Particularly preferably 600 to 50,000.

Further, as the hydroxystyrene resin, for example, at least one monomer (( Co)polymers: Co-polymers of hydroxystyrene and/or hydroxystyrene derivatives with other vinyl monomers such as styrene, vinyl ethers, acrylonitrile, vinyl chloride, acrylic esters, maleic anhydride or vinyl esters of various organic acids. Polymer; or (co)polymer of at least one monomer selected from hydroxystyrene and hydroxystyrene derivatives, and at least one monomer selected from hydroxystyrene and hydroxystyrene derivatives and other vinyl-based polymers; Examples include halogenated hydroxystyrene (co)polymers, which are halides of iodine, chlorine, bromine, etc., which are copolymers with monomers.

Among these hydroxystyrene resins, hydroxystyrene polymers, α-methyl-p-hydroxystyrene polymers, α-methyl-m-hydroxystyrene polymers, and the like are particularly preferred.

These hydroxystyrene resins can be produced by conventional anionic polymerization, cationic polymerization, radical polymerization, etc., and the production method is not limited.

The polystyrene equivalent weight average molecular weight of these hydroxystyrene resins is preferably 200 to 200,00.
0, more preferably 500 to ioo, ooo, particularly preferably 600 to 50,000.

The above novolac resins and hydroxystyrene resins are
They may be used alone or in combination of two or more. Furthermore, other resins may be used in combination.

When using other resins together, it is preferable that the resins have compatibility with each other. Examples of the combined use of resins include, for example, the combination of a novolak resin and a hydroxystyrene resin, and a combination of a novolak resin and an acrylic acid or methacrylic acid (co)polymer.

Substances that generate acids when irradiated with radiation (b) (hereinafter referred to as acid-generating substances) are substances that generate acids when irradiated with radiation such as ultraviolet rays, far ultraviolet rays, X-rays, electron beams, and visible light. .

The acids generated are, for example, sulfonic acid, phosphoric acid, iodic acid,
Inorganic acids such as diazo acids and 10-hydrogenide; or organic acids such as nitrobenzylsulfonic acid, cyanobenzylsulfonic acid, ditonzyl phosphoric acid, nitrobenzyl nitric acid, and cyanobenzyl nitric acid.

Examples of acid generating substances include onium salts such as sulfonium salts, phosphonium salts, iodonium salts, and diazonium salts; nitrobenzyl halides; halogenated hydrocarbons;
Phenyl nitrobenzylsulfonate, naphthol nitrobenzylsulfonate, O-nitrobenzyl-9,10-
Jetoxyanthracene-2-sulfonate, p-nitrobenzyl-9,10-jethoxyanthracene-2
-sulfonate, 0-nitrobenzyl-9,10-dimethoxyanthracene-2-sulfonate, p-nitrobenzyl-9,10-dimethoxyanthracene-2-sulfonate, 0-nitrobenzyl-9,10-dipropoxyanthracene-2- nitrobenzyl sulfonate esters such as sulfonate, p-nitrobenzyl-9,10-dipropoxyanthracene-2-sulfonate; benzoin sulfonate esters such as benzoin tosylate, 2-methylbenzoin tosylate; phenyl cyanobenzylsulfonate, cyanobenzyl sulfonate; Cyanobenzyl sulfonic acid esters such as naphthol benzyl sulfonate; nitrobenzyl carboxylic acid esters such as phenyl nitrobenzylcarboxylate and naphthol nitrobenzylcarboxylate; cyanobenzyl carboxylic acid esters such as phenyl cyanobenzylcarboxylate and naphthol cyanobenzylcarboxylate; Nitrobenzyl phosphate esters such as phenyl nitrobenzyl phosphate and naphthol nitrobenzyl phosphate; cyanobenzyl phosphate esters such as phenyl cyanobenzyl phosphate and naphthol cyanobenzyl phosphate; phenyl nitrobenzyl nitrate, naphthol nitrobenzyl phosphate, etc. Nitrobenzyl nitrate; Examples include cyanobenzyl nitrate such as phenyl cyanobenzyl nitrate and naphthol cyanobenzyl nitrate.

Among these, nitrobenzyl sulfonic acid ester and benzoin sulfonic acid ester are preferred.

These acid generating substances (b) are preferably 0.0 parts by weight per 100 parts by weight of the resin having a phenolic hydroxyl group (()).
It is used in a proportion of 1 to 40 parts by weight, particularly preferably 01 to 10 parts by weight.

The resin composition of the present invention further includes a substance (c) (hereinafter referred to as an acid crosslinking agent) that reacts with the resin (a) under the action of acid and heat to form a crosslinked structure between the polymer molecular chains of the resin (a). ).

Examples of such acid crosslinking agents include condensation products of urea and formaldehyde, condensation products of melamine and formaldehyde, methylol urea alkyl ethers and methylol melamine alkyl ethers obtained from these condensation products and alcohols, and hexamethylene. Tetramine can be mentioned as a suitable example.

Specific examples of condensation products of urea and formaldehyde include monomethylol urea, dimethylol urea, and the like.

Preferred examples of the condensation product of melamine and formaldehyde include hexamethylolmelamine. Compounds obtained by reacting these compounds with alcohol include, for example, monomethylol urea/methyl ether, dimethylol urea/dimethyl ether, hexamethylolmelamine, hexamethyl ether (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.).
).

These acid crosslinking agents may be used alone or in combination of two or more.

The amount of these acid crosslinking agents used is preferably 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the resin having phenolic hydroxyl groups.

The radiation-sensitive resin composition of the present invention includes the above ((), (+
]) In addition to components (c), a surfactant or the like may be added in order to improve the developability of the radiation irradiated area after the dry coating film is formed and the coating properties such as striations. Examples of surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether; Nonionic surfactants such as alkylphenol ethers and polyethylene glycol dialkyl ethers such as polyethylene glycol dilaurate and polyethylene glycol distearade; commercially available products include FTOP EF30
1. EF303, EF352 (manufactured by Shin Akita Kasei), Megafac F171, F172, F173 (manufactured by Dainippon Ink), Asahi Guard AG710 (manufactured by Asahi Glass)
, Florado FC430, FC431 (manufactured by Jujutsu 3M ■), Surf0n S-382, 5C101, 5C1
02.5C103, Sc1゜4.5CI05.5C10
Fluorinated surfactants with fluorinated alkyl groups or perfluoroalkyl groups such as 6 (manufactured by Asahi Glass Corporation), organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Corporation)
Examples thereof include acrylic acid-based or methacrylic acid-based (co)polymers Polyflow No., 75, No., 95, and WS (manufactured by Kyoeisha Yushi Kagaku Kogyo ■). The blending amount of these surfactants is per 100 parts by weight of the condensate,
It is preferably 2 parts by weight or less, more preferably 0005 to 1 part by weight.

The radiation-sensitive resin composition of the present invention may further contain dyes and pigments in order to visualize the latent image in the radiation-exposed area and to reduce the effect of halation during radiation irradiation.

Examples of the dye here include oil-soluble dyes, disperse dyes, basic dyes, methine dyes, and hydroxyazo dyes. Specifically preferred dyes include commercially available products such as Neobengelb 075 (manufactured by Basf), Neozapongelb 073 (same), Solvent Yellow 162, Macrolex Yellow, and Hydroxyazobenzene.

Furthermore, the radiation-sensitive resin composition of the present invention may also contain a storage stabilizer and an antifoaming agent, if necessary.

The radiation-sensitive resin composition of the present invention is prepared by dissolving a resin having a phenolic hydroxyl group (a), an acid generating substance (b), an acid crosslinking agent (c), and, if necessary, the various additives mentioned above, in an organic solvent. It is prepared by Examples of organic solvents used here include glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol 7-methyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and propylene glycol methyleniter acetate. ; Cellosolve esters such as methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate; Aromatic hydrocarbons such as toluene and xylene; Ketones; ethers such as benzyl ethyl ether, 1,2-dibutoxyethane, dihexyether:
Fatty acids such as caproic acid and caprylic acid; Alcohols such as 1-octatool, 1-nonanol, 1-decanol, and benzyl alcohol; Ethyl acetate, butyl acetate,
Isoamyl acetate, 2-ethylhexyl acetate, benzyl acetate, benzyl benzoate, diethyl oxalate, dibutyl oxalate, diethyl malonate, ethyl lactate, methyl lactate, propyl lactate, butyl lactate, dimethyl maleate, diethyl maleate, dibutyl maleate, phthalate Examples include esters such as dibutyl acid, dimethyl phthalate, ethylene carbonate, and propylene carbonate; cyclic lactones such as γ-butyrolactone; and urea derivatives such as dimethylimidazolidinone.

These organic solvents can be used alone or in combination.

As a method for applying the radiation-sensitive resin composition of the present invention to a substrate as a resist solution, this solution is dissolved in the above-mentioned organic solvent to a concentration of 5 to 50% by weight, and this is applied by spin coating or pouring. Examples include methods such as coating and roll coating.

A pattern can be formed using the radiation-sensitive resin composition of the present invention by the following method.

After applying the resist solution onto the substrate, a brebake process is performed for example 7 to remove the solvent and form a resist layer.
It is advantageous to work at temperatures between 0 and 120°C.

The resist layer on the substrate is irradiated with radiation such as ultraviolet rays, deep ultraviolet rays, X-rays, electron beams, visible light, etc. through a pattern. Due to radiation irradiation, components (b) are removed in the irradiated area.
Acid is produced from

Next, the substrate provided with the resist layer is heat-treated.

The heat treatment is preferably carried out at a temperature of 60 to 150°C. Optionally, such heating can be performed simultaneously with radiation irradiation.

By heating, the substance of component (c) reacts with the resin (a) to form a crosslinked structure in the polymer molecular chains of the resin (a). In this way, a strong crosslinked structure is generated in the resist layer in the irradiated area, and when it is then treated with a silicon compound, for example, hexamethylsilazane, the silicon compound penetrates and diffuses into the unirradiated area, but silicon does not remain in the irradiated area. Penetration of the compound is strongly inhibited, thus forming an etching-resistant positive latent image. This process is 100-20
Preferably it is carried out at a temperature of 0°C.

A desired positive pattern can be obtained by dry development, such as oxygen-reactive ion etching.

The positive pattern obtained from the composition of the present invention as described above is characterized by high resolution, high selectivity, high precision, and excellent reproducibility.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.

Example 1 (1) In a separable flask equipped with a stirrer, condenser and thermometer, 130 g of phenol and 65 g of m-cresol were added.
g, 250 ml of a 37% by weight aqueous formaldehyde solution, and 0.07 g of oxalic acid were charged. Next, while stirring, immerse the separable flask in an oil bath to bring the internal temperature to 100°C.
The reaction was carried out for 3 hours and 30 minutes while maintaining the temperature.

After that, the oil bath temperature was raised to 180°C, and at the same time the pressure inside the separable flask was reduced to remove water, unreacted phenol, and t
- Butylphenol, formaldehyde and oxalic acid were removed and novolak resin was recovered.

(2) Dissolve 30 g of this novolac resin in 60 g of ethyl cellosolve acetate, add 15 g of phenyl nitrobenzyl sulfonate as an acid generating substance to the acid crosslinking agent, and use Cymel 303 (hexamethylol melamine hexamethyl ether; Mitsui Sui Anami. (manufactured by Sodo)
, 6g, and a membrane filter with a pore size of 0.2μm.
was filtered to prepare a resist solution. This solution was applied onto a silicon wafer using a spinner to a dry film thickness of 1.2 μm.
Spin coat to give a coating thickness of m and heat at 85℃ on a hot plate.
Pre-baked for 1 minute.

Then, 1~10X10-'C at an accelerating voltage of 20KeV
The above resist film was irradiated with an electron beam at an angle of /cm2.

Next, heat treatment was performed on a hot plate at 100 to 130°C for 2 minutes, and then, on a hot plate at 150°C, treatment was performed with hexamethyldisilazane vapor for 3 minutes.

This silicon wafer was attached to a magnetron-enhanced reactive ion etching device (manufactured by MRC, ARIES),
When developed by oxygen-reactive ion etching, the minimum line width was 0.5g with vertical sidewalls in the areas not irradiated with the electron beam.
A 1 m positive resist pattern was obtained.

Further, the thickness of the resist pattern was 95% of that before electron beam irradiation.

Comparative Example 1 A resist solution was prepared in the same manner as in Example 1 except that the same novolac as in Example 1 was used and phenyl nitrobenzylsulfonate (acid generator) was not added, and the resist solution was applied onto a silicon wafer, prebaked, When the resist was irradiated with an electron beam, treated with hexamethyldisilazane vapor, and developed by oxygen-reactive ion etching, resist remained in the electron beam irradiated area, and a resist pattern could not be obtained.

Example 2 Into a separable flask equipped with a stirrer, a cooling tube, and a thermometer, 60 g of m-cresol, 60 g of p-cresol,
200 ml of a 37% by weight aqueous formaldehyde solution and 01 g of oxalic acid were charged. Next, the separable flask was immersed in an oil bath while stirring, and the reaction was carried out for 3 hours and 30 minutes while maintaining the internal temperature at 100°C.

After that, the oil bath temperature was raised to 180°C, and at the same time the pressure inside the separable flask was reduced to remove water, unreacted phenol,
The t-butylphenol, formaldehyde and oxalic acid were removed and the novolac resin was recovered.

30 g of this novolac resin was dissolved in 120 g of ethylene glycol monoethyl ether acetate, and p-
Nitrobenzyl-9,10-jethoxyanthracene-
0.9 g of 2-sulfonate and 6 g of Cymel 303
was added and filtered through a membrane filter with a pore size of 02 μm to prepare a resist solution.

This was applied on a silicon wafer in the same manner as in Example 1, prebaked, irradiated with an electron beam, heat treated, treated with hexamethyldisilazane vapor, and developed by oxygen reactive ion etching. As a result, a resist pattern with a minimum line width of 0.6 μm and having vertical side walls in the non-electron beam irradiated portion was obtained. Further, the thickness of the resist pattern was 95% of that before electron beam irradiation.

Comparative Example 2 Using the same novolac resin as in Example 2, Cymel 303
A resist solution was prepared in the same manner as in Example 2 except that .
When irradiated with an electron beam, heat-treated, treated with hexamethyldisilazane vapor, and developed by oxygen-reactive ion etching, resist remained in the electron-irradiated areas, and a resist pattern could not be obtained. .

Example 3 In a separable flask equipped with a stirrer, condenser and thermometer, 102 g of phenol and 18 g of t-butylphenol were added.
g, 120 ml of a 37% by weight aqueous formaldehyde solution, and 0.04 g of oxalic acid were charged. Next, while stirring, immerse the separable flask in an oil bath to bring the internal temperature to 100°C.
The reaction was carried out for 3 hours and 30 minutes while maintaining the temperature.

After that, the oil bath temperature was raised to 180°C, and at the same time the pressure inside the separable flask was reduced to remove water, unreacted phenol, and t
- Butylphenol, formaldehyde and oxalic acid were removed and novolak resin was recovered.

30 g of this novolac resin was dissolved in 120 g of ethylene glycol monoethyl ether acetate, and p-
Nitrobenzyl-9,10-jethoxyanthracene-
2-sulfonate 0.9g and Cymel 303 6
g and filtered through a membrane filter with a pore size of 0.2 μm to prepare a resist solution.

This was applied on a silicon wafer in the same manner as in Example 1, prebaked, irradiated with an electron beam, and heat treated.
Development was carried out by hexamethyldisilazane vapor treatment and oxygen reactive ion etching. As a result, a resist pattern with a minimum line width of 0.4 μm and having vertical sidewalls in the non-electron beam irradiated portions was obtained. Further, the thickness of the resist pattern was 95% of that before electron beam irradiation.

Example 4 Using the same novolak resin as in Example 2, Cymel 303
4.5 g of dimethylol urea dimethyl ether instead of
A resist solution was prepared in the same manner as in Example 3, except for using
The film was irradiated with an electron beam, heat-treated, treated with hexamethyldisilazane vapor, and developed by oxygen-reactive ion etching. As a result, a resist with a minimum line width of 0.5 μm and a vertical side wall in the non-electron beam irradiation area was obtained.

Further, the thickness ζ of the resist pattern was 96% of that before electron beam irradiation.

Example 5 Using the same novola-tsuku resin as in Example 3 (where X is p-nitrobenzyl-9,10-jethoxyanthracene-2-
A resist solution was prepared with the same composition as in Example 3 except that 3 g of benzoin tosylate was used instead of the sulfonate.

This was applied on a silicon wafer in the same manner as in Example 3, prebaked, irradiated with an electron beam, heat treated, treated with hexamethyldisilazane vapor, and developed by oxygen-reactive ion etching. . As a result, the minimum linewidth force <Q with vertical sidewalls in the non-electron beam irradiation area.

A resist pattern of 45 μm was obtained.

Further, the thickness of the resist pattern was 96% of that before electron beam irradiation.

[Effects of the Invention] When the positive radiation-sensitive resin of the present invention is used as a resist for dry development, the acid generated when irradiated with radiation acts on the acid crosslinking agent during the heat treatment after irradiation, and the resist In order to strengthen the cross-linking, absorption of silicon compounds in the irradiated area
Effectively suppress the reaction.

Therefore, according to the present invention, a positive etching image with high resolution, high selectivity, and high precision can be obtained with good reproducibility.

Therefore, according to the present invention, it is possible to further improve the degree of integration of products such as semiconductor integrated circuits, and to improve the yield.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Agent: Patent Attorney Masataka Oshima

Claims (1)

[Scope of Claims] 1. (a) a resin having a phenolic hydroxyl group, (b) a substance that generates an acid upon irradiation with radiation, and (c) a substance that reacts with the resin (a) by the action of acid and heat. A radiation-sensitive resin composition for positive dry development, comprising: a substance that forms a crosslinked structure between polymer molecular chains of the resin (a).