JPH06194848A - Method for forming pattern on electronic parts - Google Patents

Abstract

PURPOSE:To form a stabilized pattern having a rectangular cross section after a resist is formed, capable of being finely worked and without the sensitivity and resolution being changed by the retention time after exposure on the electronic parts. CONSTITUTION:A radiation-sensitive composition contg. a compd. generating acid when irradiated with chemical radiation and a compd. having at least one bond capable of being decomposed by the acid is applied on a substrate to form a radiation-sensitive layer, the layer surface is treated, the surface- treated radiation-sensitive layer is exposed to form a desired pattern, and the radiation-sensitive layer is developed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method used for fine processing of electronic parts such as large scale semiconductor integrated circuits (LSI).

[0002]

2. Description of the Related Art In the field of electronic parts such as semiconductor integrated circuits which require various fine processing, a fine processing technique by photolithography is adopted. In this technique, a photoresist film is formed on a semiconductor substrate such as a silicon wafer by spin coating. After pattern exposure of the resist film, development, rinsing and the like are applied to form a resist pattern. Further, the exposed substrate portion is etched using the resist pattern as an etching mask to form fine lines and openings.

In the pattern exposure, in order to form a fine pattern, the shorter the wavelength of the light used, the better the short wavelength light such as excimer laser, and further the short wavelength electron beam or X-ray. A finer pattern can be formed.

However, since the conventional resist has a large absorption for short-wavelength light, it is not possible to sufficiently reach the deep portion of the resist film for the light rays. as a result,
The cross-sectional shape of the resist pattern after development becomes a triangle for a positive resist and an inverted triangle for a negative resist, which causes a problem that the function as an etching mask is significantly impaired.

As a resist for solving such a problem, a chemical amplification type resist has been conventionally proposed. The chemically amplified resist contains a compound that generates an acid upon irradiation with light (photoacid generator), and a compound that decomposes a hydrophobic group due to the generated acid and changes to a hydrophilic substance. Specific examples of the resist include a positive resist containing a polymer in which a hydroxyl group of poly (p-hydroxystyrene) is blocked with a butoxycarbonyl group and an onium salt, and m
-A positive resist containing cresol novolac resin, naphthalene-2-carboxylic acid-tert-butyl ester, and triphenylsulfonium salt, and 2,2-bis (4-tert-butoxycarbonyloxyphenyl) propane or poly-resist. A positive resist containing phthalaldehyde and an onium salt may be used.

Since the photo-acid generator acts as a catalyst,
Since even a small amount reacts efficiently, the reaction sufficiently proceeds to the deep part of the resist film, and it becomes possible to form a resist pattern having steep side surfaces. The above-mentioned chemically amplified resist is described in the following documents. 1) H. Ito, C, G, Wilson, J. et al. M. J,
Franchet, U.S.A. S. Patent 4,49
1,628 (1985).

A positive resist containing a polymer obtained by modifying a hydroxyl group of poly (p-hydroxystyrene) with a butoxycarbonyl group and an onium salt which is a compound that generates an acid upon irradiation with light is disclosed.

2) M. J. O Brien, J .; V. C
rivello, SPIE Vol, 920, Adva
nces in Resist Technology
and Processing, p42, (198
8).

A positive resist containing an m-cresol-novolak resin, naphthalene-2-carboxylic acid-tertiarybutyl ester, and a triphenylsulfonium salt which is a compound that generates an acid upon irradiation with light is disclosed.

3) H. Ito, SPIE Vol, 92
0, Advances in Resist Techn
logic and Processing, p33,
(1988).

A positive resist containing 2,2-bis (4-tertiarybutoxycarbonyloxyphenyl) propane, polyphthalaldehyde, and an onium salt which is a compound that generates an acid upon irradiation with light is disclosed.

However, since the chemically amplified resist has high sensitivity, it is easily affected by the process atmosphere, and there is a problem that the sensitivity and the resolution are changed depending on the standing time after exposure. This is described in the following document.

A. MacDonald, al. SPIE
Vol, 1466, Advances in Res
ist Technology and Process
ing, p2, (1991). It is disclosed that a trace amount of dimethylaniline contained in the atmosphere forms an insolubilized layer on the surface of the resist film and reduces the resolution performance of the resist.

[0014]

SUMMARY OF THE INVENTION According to the present invention, the irradiation of actinic radiation reaches a deep portion, the cross section after resist formation becomes short and good microfabrication can be performed, and the sensitivity and resolution depend on the standing time after exposure. An object of the present invention is to provide a pattern forming method for an electronic component that can form a stable pattern that does not change.

[0015]

A method for forming a pattern of an electronic component of the present invention comprises a compound capable of generating an acid upon irradiation with actinic radiation and a compound having at least one bond capable of being decomposed by the acid. A step of applying a radiation-sensitive composition onto a substrate to form a radiation-sensitive layer; a step of treating the surface of the radiation-sensitive layer; and an exposure step for forming a desired pattern on the surface-treated radiation-sensitive layer. And a step of developing the radiation-sensitive layer.

[0016]

The resist containing the compound capable of generating an acid upon irradiation with actinic radiation and the compound having at least one bond capable of being decomposed by the acid is applied onto the substrate to form a resist layer. By treating the surface of the resist layer with an organic solvent or a basic compound to form an altered layer on the surface, harmful components in the process atmosphere that inhibit the decomposition reaction of the compound are blocked. Then, in order to form a desired pattern, it is exposed and then developed. As a result, since the irradiation of actinic radiation reaches the deep part of the resist layer, the cross section of the resist layer has a short shape, and moreover, a stable pattern can be formed in which the sensitivity and resolution do not change depending on the standing time after exposure.

[0017]

EXAMPLES Examples of the pattern forming method for electronic parts of the present invention will be described below.

First, a radiation-sensitive composition containing a compound capable of generating an acid upon irradiation with actinic radiation and a compound having at least one bond capable of being decomposed by the acid is applied onto a substrate by a spin coating method or a deposition method. After that, the radiation-sensitive composition layer (resist film) is formed by drying at 200 ° C. or lower, preferably 70 to 150 ° C.

The substrate may be, for example, a silicon wafer, a silicon wafer having various steps on the surface of which various insulating films and electrodes are formed, a blank mask, and various semiconductor wafers.

The actinic radiation is selected optimally according to the properties of the compound capable of generating an acid upon irradiation with the actinic radiation which is the first component. For example, the i-line of a mercury lamp, h
Rays, g rays, various kinds of ultraviolet rays or X rays such as Kr F rays and Ar F rays which are excimer lasers, electron rays, ion beams and the like.

The compound capable of generating an acid upon irradiation with actinic radiation, which is the first component of the radiation-sensitive composition, is not particularly limited, and various known compounds and mixtures can be used. For example, diazonium salt, phosphonium salt, sulfonium salt, iodonium salt, organic halogen compound, orthoquinone-diazide sulfonyl chloride and the like can be mentioned.

The compound having at least one bond capable of being decomposed by the acid, which is the second component of the radiation-sensitive composition, is not particularly limited as long as it is decomposed by the acid and the solubility in the developing solution is changed. Ester or ether of a phenol compound is suitable. Examples of the phenol compound include phenol, cresol, xysol, bisphenol A, bisphenol S, hydroxybenzophenone, phenolphthalein, polyvinylphenol, and novolac resin. These hydroxy groups are esterified or etherified with a suitable esterifying agent or etherifying agent. Examples of the ester or ether to be introduced include methyl ester, ethyl ester, n-propyl ester, isopropyl ester, tertiary (t
ert) -butyl ester, n-butyl ester, isobutyl ester, benzyl ester, tetrahydropyranyl ether, benzyl ether, methyl ether, ethyl ether, n-propyl ether, isopropyl ether, tert-butyl ether, allyl ether,
Methoxymethyl ether, p-bromophenacyph ether, trimethylsilyl ether, benzyloxycarbonyl ether, tert-butoxycarbonyl ether, tert-butyl acetate, 4-tert-butylbenzyl ether and the like can be mentioned.

The radiation-sensitive composition permits the addition of an alkali-soluble polymer as a third component in addition to the first and second components. Such an alkali-soluble polymer has the function of adjusting the dissolution rate of the radiation-sensitive layer in an alkali developing solution to enhance the resolution of the pattern. Examples of the alkali-soluble resin include phenol novolac resin, cresol novolac resin, xyresole novolac resin, vinylphenol resin, and the like.

In the radiation-sensitive composition, in addition to the first component, the second component, and the third component, if necessary, a surfactant as a coating film modifying agent or a coating material as an antireflection agent is used. You may mix.

The compounding amount of the compound capable of generating an acid upon irradiation with actinic radiation, which is the first component, is 0.1 to 30% by weight, more preferably 0.3% by weight based on the solid content of the radiation-sensitive composition.
It is preferably in the range of ˜15% by weight. The reason for this is that if the content is less than 0.1% by weight, it may be difficult to obtain sufficient photosensitivity, whereas if it exceeds 30% by weight, it may be difficult to form a uniform radiation-sensitive layer.

In the alkali-soluble polymer as the third component, the total amount of the compound having at least one bond capable of being decomposed by the acid and the alkali-soluble polymer as the second component is 100 parts by weight. At this time, it is desirable to add 90 parts by weight or less, preferably 80 parts by weight or less. The reason for this is that if the amount of the alkali-soluble polymer compounded exceeds 90 parts by weight, the difference in dissolution rate between the exposed and unexposed areas becomes small and the resolution in pattern formation may deteriorate.

The radiation-sensitive composition is prepared by dissolving the first component, the second component, the alkali-soluble polymer as the third component, which is blended as necessary, in an organic solvent, and filtering. It

Examples of the organic solvent include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone and methyl isobutyl ketone, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, ethyl cellosolna acetate, butyl cellosolve, butyl cellosolve acetate and the like, acetic acid. Ester-based solvents such as ethyl, butyl acetate, isoamyl acetate, ethyl lactate, methyl lactate, 2-butanol, isoamyl alcohol, alcohol solvents such as diethylene glycol, ethylene glycol diethyl ether, diethylene glycol monoethyl ether, ethyl carbitol, etc. Alcohol derivative solvent, monophorin, N-methyl-2-
Examples thereof include pyrrolidone.

These solvents may be used alone or in the form of a mixture. Then, the surface of the radiation-sensitive composition layer is treated with an organic solvent to form an altered layer on the surface of the radiation-sensitive composition layer.

The organic solvent used for the surface treatment is not particularly limited, and various organic solvents can be used. For example, toluene, chlorobenzene, xylene,
Examples thereof include ethylbenzene, methylene chloride, propylene chloride, hexane and cyclohexane.

Examples of the surface treatment method with the organic solvent include a method of exposing to the vapor of the organic solvent, a method of immersing in the organic solvent, and a method of applying the organic solvent, but the method is not particularly limited.

Then, through the mask having a desired pattern on the radiation-sensitive layer surface-treated with the organic solvent, i-line, h-line, g-line of a mercury lamp and Kr which is an excimer laser.
Pattern exposure is performed by irradiating ultraviolet rays such as F rays and Ar F rays or X rays. In addition, electron beam without using a mask,
Direct pattern exposure may be performed by scanning with an ion beam or the like. A bond capable of generating an acid from a compound capable of generating an acid which is the first component of the radiation sensitive composition upon exposure by the actinic radiation irradiation, and the acid being decomposable by an acid which is the second component of the radiation sensitive composition. With a compound having at least one of Subsequently, the radiation-sensitive layer after pattern exposure is generally heat-treated at a temperature of 70 to 160 ° C., preferably 80 to 130 ° C. to accelerate the amplification reaction. Next, the radiation-sensitive layer after the heat treatment is developed with an alkaline aqueous solution, the developer is washed away with pure water, and then the substrate is dried.

Examples of the alkaline aqueous solution which is the developer include inorganic alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate and sodium metasilicate, tetramethylammonium hydroxide aqueous solution and trimethylhydroxyethylammonium hydro. It is possible to use an organic alkaline aqueous solution such as an oxide aqueous solution, or one to which these alcohols, a surfactant, etc. are added.

According to the above-mentioned embodiments, the radiation-sensitive layer is formed on the substrate, the surface of the radiation-sensitive layer is treated with an organic solvent, and then pattern exposure is carried out using actinic radiation such as ultraviolet rays to obtain the radiation-sensitive layer. An acid is generated from a compound capable of generating an acid upon irradiation with actinic radiation, which is the first component of the radiation-sensitive composition, and the acid has at least one bond capable of being decomposed by the acid which is the second component of the radiation-sensitive composition. Reacts with a compound having the same to decompose the compound. By heating at a predetermined temperature after pattern exposure, the reaction can proceed not only on the surface of the radiation-sensitive layer but also in the depth direction thereof. Further, by forming an altered layer on the surface by treating the surface of the radiation-sensitive layer with an organic solvent,
It is possible to block harmful components in the process atmosphere that inhibit the reaction. As a result, it is possible to suppress the change in sensitivity and resolution due to the atmosphere after exposure, which is a problem in the chemically amplified resist.

Although the surface of the radiation-sensitive layer was treated with an organic medium in the above-mentioned examples, it may be treated with a basic compound. In this case, it is possible to obtain the same effect as that obtained when treated with the organic medium.

The basic compound used for the surface treatment is not particularly limited, and various amine compounds and the like can be used. For example, triethylamine, aniline,
Pyridine, diethylamine, ammonia, tetramethylammonium hydroxide, hexamethyldisilazane, triphenylamine, 2,4,5-triphenylimidazole, 2-phenylimidazole, 4,4'-diaminodiphenylmethane, nicotinic acid amide, 2- Examples thereof include ethylimidazole, 3,3′-diamino-4-4′-dihydroxydiphenyl, 2,2,2-trifluoroacetamide, and benzothiazole.

As the method of surface treatment with the basic compound, there are a method of exposing to the vapor of the basic compound, a method of immersing in the solution in which the basic compound is dissolved, a method of spraying the solution in which the basic compound is dissolved, and the like. Examples thereof include, but are not limited to. The radiation-sensitive composition material surface-treated with a basic compound, the step of exposing to form a desired pattern and the step of developing the radiation-sensitive layer are described above, the surface treatment of the radiation-sensitive layer is performed in an organic medium. The same as in Next, a specific example of adjusting the radiation-sensitive composition will be described below.

Compounds capable of generating an acid upon irradiation with radiation (compounds capable of generating an acid) shown in Table 1 below and compounds having at least one bond capable of decomposing by the generated acid shown in Table 2 below (decomposable by an acid). Compound) and an alkali-soluble polymer shown in Table 3 below are blended in the ratio shown in Table 4 below, and dissolved in an organic solvent of the type and amount shown in Table 4 above, and then a 0.2 μm cellulose membrane filter is added. Six radiation-sensitive compositions were prepared by filtering with.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4] Hereinafter, the results of comparison between the first to fourth examples and the examples in which the surface treatment of the radiation-sensitive composition is not performed for each example will be described. Example 1

First, the radiation-sensitive composition RE-1 shown in Table 4 above was spin-coated on a 6-inch silicon wafer and prebaked for 90 seconds on a hot plate at 90 ° C. to give a 1.0 μm thick film. A radiation layer (resist film) was formed. Subsequently, it was left in an atmosphere of hexamethyldisilazane for 5 minutes for surface treatment. Then, after exposing with a Kr F excimer laser stepper, the unleaved sample and the sample left for 2 hours are put on a hot plate at 100 ° C. for 90 minutes.
After baking for 2 seconds, the resist film is developed by immersing in a 2.38% tetramethylammonium hydroxide aqueous solution (hereinafter, abbreviated as TMAH aqueous solution) for 30 seconds, and then washed and dried to form a resist pattern. did.

The obtained resist pattern was observed with a scanning electron microscope (hereinafter abbreviated as SEM). As a result, the exposure amount was 25 mJ / cm ^{2 for} both the sample not exposed after exposure and the sample left for 2 hours. A 0.30 μm pattern was resolved, and no effect was observed by leaving it after exposure. Comparative Example 1 A resist pattern was formed under the same conditions as in Example 1 except that the surface treatment of the resist film with hexamethyldisilazane was not performed.

Observation of the obtained resist pattern by SEM revealed that the unexposed sample after exposure had an exposure dose of 20 m.
J / cm ² The 0.30 μm pattern was resolved by
The sample left for 2 hours had an exposure dose of 40 mJ / cm ² It was only possible to resolve a pattern of 0.50 μm. Example 2

First, the radiation-sensitive composition RE-2 shown in Table 4 was spin-coated on a 6-inch silicon wafer and prebaked on a hot plate at 90 ° C. for 300 seconds to give a thickness of 1.0 μm. A radiation sensitive layer (resist film) was formed. Subsequently, it was left in a triethylamine atmosphere for 10 minutes for surface treatment. Then, after exposing with a KrF excimer laser stepper, the unleaved sample and the sample left for 2 hours were placed on a hot plate at 120 ° C. for 1 hour.
Bake for 20 seconds. Next, TM with 2.38% concentration
The resist film was developed by immersing it in an AH aqueous solution for 30 seconds, followed by washing with water and drying to form a resist pattern.

When the obtained resist pattern was observed by SEM, an exposure amount of 45 mJ / cm ² was obtained for both the samples which were not left after exposure and left for 2 hours. A 0.30 μm pattern was resolved, and no effect was observed by leaving it after exposure. Comparative Example 2 A resist pattern was formed under the same conditions as in Example 2 except that the resist film was not surface-treated with triethylamine.

Observation of the obtained resist pattern by SEM revealed that the unexposed sample after exposure had an exposure dose of 40 m.
J / cm ² The 0.30 μm pattern was resolved by
The exposure amount of the sample left for 2 hours was 60 mJ / cm ² Only a 0.5 μm pattern could be resolved. Example 3

First, the radiation-sensitive composition RE-3 shown in Table 4 above was spin-coated on a 6-inch silicon wafer and prebaked on a hot plate at 130 ° C. for 120 seconds to give a radiation-sensitive composition having a thickness of 1.0 μm. A radiation layer (resist film) was formed. Subsequently, it was left in an aniline atmosphere for 10 minutes for surface treatment. Next, the electron beam is used to accelerate the voltage to 20 k
After irradiating under the condition of eV to draw a pattern, a sample that was not left and a sample that was left for 2 hours after drawing were
1. After baking for 120 seconds on a hot plate at ℃, 2.
A resist pattern was formed by immersing the resist film in a 38% aqueous TMAH solution for 30 seconds to develop the resist film, followed by washing with water and drying.

When the obtained resist pattern was observed by SEM, an electron beam irradiation amount of 5 μc / cm ² was observed for both the samples which were not left after drawing and left for 2 hours. The pattern of 0.25 μm was resolved in FIG. Comparative Example 3 A resist pattern was formed under the same conditions as in Example 3 except that the surface treatment of the resist film with aniline was not performed.

Observation of the obtained pattern by SEM revealed that the sample which had not been left after drawing had an electron beam irradiation amount of 5 μc /
cm ² Although a 0.25 μm pattern was resolved by the sample, the sample left for 2 hours after drawing had an electron beam irradiation amount of 8 μc / c.
m ² It was only possible to resolve a pattern of 0.40 μm. Example 4

First, the radiation-sensitive composition RE-4 shown in Table 4 was spin-coated on a 6-inch silicon wafer and prebaked on a hot plate at 90 ° C. for 300 seconds to give a radiation-sensitive composition having a thickness of 1.0 μm. A radiation layer (resist film) was formed. Then leave it in an ammonia atmosphere for 5 minutes,
A surface treatment was applied. Then after exposing with i-line stepper,
Samples that have not been left and samples that have been left for 2 hours are
1. After baking for 120 seconds on a hot plate at ℃, 2.
A resist pattern was formed by immersing the resist film in a 38% aqueous TMAH solution for 30 seconds to develop the resist film, followed by washing with water and drying.

When the obtained resist pattern was observed by SEM, a 0.35 μm pattern was resolved at an exposure time of 75 msec for both the sample that had not been left after exposure and the sample that had been left for 2 hours. I was not able to admit. Comparative Example 4 A resist pattern was formed under the same conditions as in Example 4 except that the surface treatment of the resist film with ammonia was not performed.

Observation of the obtained resist pattern by SEM revealed that a 0.35 μm pattern was resolved in an untreated sample after exposure with an exposure time of 75 msec. 90m
Only sec up to 0.45 μm could be resolved. Example 5 As a radiation-sensitive composition, RE-5 described in Table 4 above was used.
A resist pattern was formed under the same conditions as in Example 1 except that was used.

When the obtained resist pattern was observed by SEM, the exposure amount was 34 mJ / cm ^{2 for} both the samples which were not left after exposure and left for 2 hours. A 0.30 μm pattern was resolved, and no effect was observed by leaving it after exposure. Comparative Example 5 A resist pattern was formed under the same conditions as in Example 5 except that the surface treatment of the resist film with hexamethyldisilazane was not performed.

Observation of the obtained resist pattern by SEM revealed that the sample not exposed after exposure had an exposure amount of 32 m.
J / cm ² The 0.30 μm pattern was resolved by
The sample that was left for 2 hours had an exposure dose of 45 mJ / cm ^2. It was only possible to resolve a pattern of 0.50 μm. Example 6 As a radiation-sensitive composition, RE-6 described in Table 4 above was used.
A resist pattern was formed under the same conditions as in Example 1 except that was used.

Observation of the obtained resist pattern by SEM revealed that the sample was left unexposed for 2 hours and the exposure amount was 30 mJ / cm ^{2 for} both samples. The pattern of 0.30 μm was resolved, and no effect was observed by leaving it after exposure. Comparative Example 6 A resist pattern was formed under the same conditions as in Example 6 except that the surface treatment of the resist film with hexamethyldisilazane was not performed.

Observation of the obtained resist pattern by SEM revealed that the sample not exposed after exposure had an exposure amount of 28 m.
J / cm ² The 0.30 μm pattern was resolved by
The sample left for 2 hours had an exposure dose of 40 mJ / cm ² It was possible to resolve only a 0.45 μm pattern.

[0059]

According to the present invention, the irradiation of actinic radiation reaches a deep portion, and the cross section after resist formation becomes a short shape,
In particular, it is possible to obtain a pattern forming method of an electronic component that can be effectively used for fine processing in a semiconductor device such as an LSI and that can form a stable pattern without changing sensitivity and resolution depending on a standing time after exposure.

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Claims (3)

[Claims] 1. A compound capable of generating an acid upon irradiation with actinic radiation and at least one bond capable of being decomposed by the acid.
A step of forming a radiation-sensitive layer by applying a radiation-sensitive composition containing a compound having one to a substrate, a step of treating the surface of the radiation-sensitive layer, and a step of treating the surface-treated radiation-sensitive layer with a desired amount. A method for forming a pattern of an electronic component, which comprises the step of exposing to form a pattern and the step of developing the radiation-sensitive layer. 2. The pattern forming method for an electronic component according to claim 1, wherein the step of treating the surface of the radiation-sensitive layer includes a step of treating with an organic solvent. 3. The method for forming a pattern of an electronic component according to claim 1, wherein the step of treating the surface of the radiation-sensitive layer includes a step of treating with a basic compound.