JPH05323590A - Chemical amplifying resist composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a chemically amplified resist composition which can reduce the influence of acid consumption in the surface layer of a resist film and can obtain a good pattern shape with excellent resolution. [Structure] The chemically amplified resist composition of the present invention contains two or more acid generators. Preferably, at least one of the acid generators is a compound that substantially contributes to the reaction that changes the solubility of the resist film in the developing solution,
Others are compounds that contribute less to or do not substantially contribute to the reaction as compared to this compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resist composition. More specifically, the present invention relates to a resist composition useful for forming a pattern of a semiconductor device, particularly a resist composition containing two or more compounds that generate an acid upon irradiation with ionizing radiation or a compound that promotes the generation of an acid. Regarding things. The resist composition of the present invention is suitable for large-scale integrated circuits (LS
I), it can be advantageously used for manufacturing a semiconductor device such as a very large scale integrated circuit (VLSI), and a highly integrated semiconductor device can be provided.

[0002]

2. Description of the Related Art With recent high integration of semiconductor integrated circuits, miniaturization of semiconductor integrated circuit patterns is required,
Strict performance is also required for resist materials that are indispensable when forming these patterns. Therefore, in recent years, as a material developed to meet all the requirements of resolution, sensitivity, and dry etching resistance, a chemically amplified resist containing an acid generator as one of the main components other than the base resin. Is getting attention.

There are several types of chemically amplified resists. For example, as an example of a negative resist,
Some are composed mainly of an alkali-soluble base resin, a crosslinking agent, an acid generator and a solvent. In addition, examples of positive resists include those composed mainly of an alkali-soluble base resin, a dissolution inhibitor, an acid generator and a solvent, or a portion of the alkali-soluble resin modified to make it insoluble in an alkali solution. Some of them are composed mainly of the above-mentioned base resin, acid generator and solvent.

In order to form a pattern using a chemically amplified resist, a resist film is usually formed on a substrate by spin coating, the film is prebaked, and the pattern is formed by irradiating ionizing radiation through a reticle. Expose.
When the ionizing radiation is charged particles such as an electron beam, pattern exposure is usually performed by scanning the resist film without passing through a reticle. In the resist film, an acid is generated from the acid generator by the action of the ionizing radiation at the portion irradiated with the ionizing radiation.

In the case of a negative resist, the acid thus generated in the resist film activates the crosslinking agent by heat treatment after exposure, and the activated crosslinking agent renders the base resin insoluble in alkali. To do. In the case of the positive type, the acid generated in the resist film decomposes the dissolution inhibitor by heat treatment after exposure to allow the base resin to dissolve in the alkaline developer, or after the exposure, it is also possible. The reaction of the base resin with the modified portion of the base resin causes the resin to return to an alkali-soluble resin.

Next, by developing with an alkaline developing solution, in the case of a negative resist, the base resin which remains alkali-soluble in the portion which is not irradiated with ionizing radiation is dissolved in the developing solution to form a negative pattern. In the case of a positive resist, a portion of the alkali-soluble base resin irradiated with ionizing radiation is dissolved in a developing solution to form a positive pattern.

During each of the above-described reactions, the acid generated from the acid generator activates many reaction points as a catalyst, so that high sensitivity can be realized and, in comparison with the conventional photoresist, it is more sensitive. High resolution is realized because absorption by the agent can be reduced. Further, since the phenolic resin can be used as the base resin as in the conventional photoresist, the resistance of the resist film in the subsequent dry etching step is maintained.

[0008]

However, in the pattern formation using such a conventional chemically amplified resist, a resist film is formed due to an alkaline impurity or the like in which the acid generated by the irradiation of ionizing radiation is present in a small amount in the outside air. In the negative resist, the upper part of the formed pattern was rounded, while in the positive resist, there was a phenomenon that an eave-shaped protrusion was formed on the upper part of the pattern remaining after development. This phenomenon causes a particularly serious problem in the case of a positive resist, and in a serious case, it may even cover the pattern opening formed by the projection, which leads to the miniaturization of the pattern required for the semiconductor integrated circuit. Was difficult to realize.

In view of such defects in the conventional chemically amplified resist, the present invention can reduce the influence of the consumption of acid in the surface layer portion of the resist film, thereby providing excellent resolution and good pattern shape. It is intended to provide a chemically amplified resist composition capable of obtaining

[0010]

The chemically amplified resist composition of the present invention is characterized by containing two or more compounds that generate an acid upon irradiation with ionizing radiation or a compound that promotes the generation of an acid. To do.

The resist composition of the present invention comprises a base resin and
A compound that generates an acid upon irradiation with ionizing radiation or a compound that promotes the generation of an acid, and a solvent as a main component, and other components such as a crosslinking agent and a dissolution inhibitor depending on the type of the resist composition. Can be included.

The compound that generates an acid upon irradiation with ionizing radiation or the compound that promotes the generation of an acid is a compound generally known as an "acid generator", and examples thereof include Ph ₂ I ⁺ SbF. ^{_{6 -, Ph 3 S + SbF}} 6 - onium salts such ^{_{as, (Ph 2 I +) 2}} CO 3 2-, (Ph 3 S
⁺ ) ₂ CO ₃ ^2-, etc., a salt containing carbonate ion, Ph ₂ I ⁺ H
Examples include salts containing hydrogen carbonate ions such as CO ₃ ⁻ and Ph ₃ S ⁺ HCO ₃ ⁻ , triazine compounds having a chloromethyl group, other organic halides, and tosylate compounds such as orthonitrobenzyl alcohol sulfonate. be able to. (Ph in the above formula represents a phenyl group.)

In the present invention, two or more compounds are used together as an acid generator in a chemically amplified resist composition. By including two or more acid generators in this way, the absolute amount of the acid generated by exposure can be increased, while each of the acids derived from these acid generators is the surface layer of the resist film. The amount consumed due to impurities in the outside air can be relatively reduced.

Further, it is more advantageous to select, as the two or more kinds of acid generators, those having a significant difference in the degree of contributing to the reaction of changing the solubility of the resist film in the developing solution after irradiation with ionizing radiation. is there. That is, at least one of the acid generators is a compound that substantially contributes to the reaction that changes the solubility of the resist film after irradiation with ionizing radiation, while other acid generators are compared to this compound. When the compound is a compound that hardly contributes to the reaction, or a compound that does not substantially contribute to the reaction, the solubility of the resist film in the developer of the acid consumed in the surface layer of the resist film is changed. It is more advantageous for improving the resist pattern shape and resolution because the consumption of the acid derived from the compound that substantially contributes to is relatively reduced. When all the generated acid contributes to the reaction that changes the solubility of the resist film, the addition amount of these acid generators must be limited in terms of the dimensional control of the pattern to be formed. Thus, the acid generator that does not contribute to the reaction can be added to the maximum extent within the limits of factors unrelated to pattern size control, such as resist film solubility and film properties, and resist film It is possible to relatively reduce the consumption of the acid derived from the compound that contributes to the change in solubility, and prevent the deterioration of the resist pattern shape and the resolution.

The acid generation efficiency of the acid generator is also related to the resist pattern shape and resolution. When the acid generation efficiency of the acid generator that does not or hardly contributes to the reaction that changes the solubility of the resist film is higher than that of the acid generator that contributes to the reaction, it controls the dimensional control in the resist film. The relative amount of acid is extremely small. Therefore, most of the acid consumed in the surface layer can be used as an acid that does not contribute to the reaction, and it is more advantageous to reduce the eaves generation in the case of a positive resist and the roundness of the resist pattern upper portion in the case of a negative resist. Is.

The reactivity of the generated acid with contaminants in the outside air also affects the resist pattern shape and resolution.
Acids that do not or do not contribute substantially to the reaction that changes the solubility of the resist film react with contaminants in the open air rather than acids from the acid generator that contribute to the reaction If the property is low, in order to reduce the consumption of the acid derived from the acid generator that contributes to the reaction in the surface layer, the amount of the acid derived from the acid generator that contributes to the reaction or is difficult to contribute is relatively reduced. I have to do a lot.

Furthermore, whether or not one acid generator contributes to the reaction that changes the solubility of the resist film in the developing solution depends on the type of the base resin. For example, t is the unit by which the base resin becomes the source of solubility in the developer.
In the case of a copolymer containing a unit containing a butyl group, an onium salt, a tosylate compound, etc. change the solubility of the resist film, and a salt containing carbonate ion, a salt containing hydrogen carbonate ion, an organic halide, etc. Does not change solubility.

As described above, the two or more compounds used as the acid generator in the chemically amplified resist composition of the present invention are selected according to the kind of the base resin constituting the composition, and thus selected. Each of the above compounds should be added to the composition in an appropriate addition amount determined depending on the efficiency of acid generation and the reactivity of the generated acid with contaminants in the ambient air. Preferably, the addition amount of the acid generator that does not substantially contribute to the change in the solubility of the base resin in the developer or the degree of the contribution to this change is lower than that of other acid generators is The acid from the generator is sufficient to reduce the amount of acid from the other acid generator consumed due to the reaction with contaminants in the open air.

Needless to say, the resist composition of the present invention can be used in addition to the acid generator that substantially contributes to the reaction that changes the solubility of the resist film in the developing solution, and in addition to the acid generator, the above-mentioned reaction can be achieved. It may comprise either an acid generator having a lower degree of contribution or an acid generator that does not substantially contribute to the reaction, or to the above reaction with an acid generator having a lower degree of contribution to the reaction. It may contain both of the acid generators that do not substantially contribute. Furthermore, neither the acid generator that substantially contributes to the reaction that changes the solubility of the resist film in the developer nor the acid generator that does not substantially contribute to this reaction or has a lower degree of contribution to this reaction. Any one kind or two or more kinds can be optionally contained in one resist composition.

The base resin constituting the chemically amplified resist composition of the present invention may be any resin used as a base resin in a conventional chemically amplified resist composition. That is, depending on the intended chemically amplified resist composition, it is possible to use one that is soluble in an alkaline developing solution or one that is obtained by modifying a part of the alkali-soluble resin to make it insoluble in the alkaline developing solution.

When the base resin is an alkali-soluble resin, the chemically amplified resist composition contains a dissolution inhibitor (in the case of a positive resist) or a cross-linking agent (negative) as another component. Type resist).

The term "ionizing radiation" as used herein means electromagnetic waves such as visible light, ultraviolet light and X-rays, and particle beams such as electron beams and ion beams.

[0023]

The two or more acid generators contained in the chemically amplified resist composition of the present invention increase the absolute amount of the acid generated by exposure, while at the same time each of the acids derived from these acid generators. Relatively reduces the amount consumed by impurities in the outside air at the surface layer of the resist film, and improves the resist pattern shape and resolution.

Further, among the two or more kinds of acid generators contained in the chemically amplified resist composition of the present invention, it substantially affects the reaction of changing the solubility of the resist film in the developing solution after irradiation with ionizing radiation. An acid generator that does not contribute, or a compound that is less likely to contribute to this reaction than other acid generators, acts as a scavenger and substantially contributes to the reaction that changes the solubility of the resist film. The amount of the acid derived from is relatively reduced in the surface layer of the resist film due to impurities in the outside air, and further contributes to the improvement of the resist pattern shape and resolution.

[0025]

EXAMPLE 1 In 375 parts of a solvent (ethyl lactate), 100 parts of a copolymer of vinylphenol and t-butylmethacrylate as a base resin, 5 parts of triphenylsulfonium triflate as an acid generator, and A positive chemically amplified resist composition containing 5 parts of tris-2,3-dibromopropyl isocyanurate was prepared. Among the acid generators used, triphenylsulfonium triflate is a compound that contributes to changing the solubility of the base resin in a developing solution, and is tris-2,3-dibromopropyl isocyanurate from the other. It has been found that the generated acid acts as a scavenger of contaminants in the outside air at the surface layer of the resist film and is hardly related to the change in the solubility of the base resin.

The prepared resist composition was applied on a silicon substrate to a thickness of 0.7 μm. The substrate was placed on a hot plate, the formed resist film was pre-baked at 90 ° C. for 90 seconds, and then the resist film was exposed by a KrF excimer laser stepper. Subsequently, heat treatment was performed at 110 ° C. for 60 seconds, and dip development was performed for 60 seconds with a 2.38% tetramethylammonium hydroxide aqueous solution.

A line and space pattern of 0.3 μm was resolved at an exposure dose of 5 mJ / cm ² . Also, with the line and space pattern and the hole pattern,
No eave-like overhang was observed on the upper part of the formation pattern.

Example 2 Tris-2,3 which generates an acid which acts as a scavenger
-In place of dibromopropyl isocyanurate, bis-2,4-which also generates an acid which also acts as a scavenger
Trichloromethyl-6-phenyl-s-triazine was added to 5
Example 1 was repeated with the exception that a positive chemically amplified resist composition was included in parts.

In this case, at an exposure dose of 6 mJ / cm ² ,
A line and space pattern of 3 μm was resolved. In addition, neither the line-and-space pattern nor the hole pattern was found to have an eave-like overhang on the upper part of the formed pattern.

Comparative Example An acid containing 100 parts of a copolymer of vinylphenol and t-butylmethacrylate in 5 parts of ethyl lactate and 5 parts of triphenylsulfonium triflate as an acid generator to generate an acid acting as a scavenger. Example 1 was repeated except that a conventional positive chemically amplified resist composition containing no generator was used.

In this case, at an exposure dose of 5 mJ / cm ² ,
A 35 μm line and space pattern was resolved. However, in these line-and-space patterns and hole patterns, eave-like overhangs were observed above the formation pattern. Further, in the 0.30 μm line-and-space pattern, it was confirmed that the spaces were covered by eave-shaped overhangs generated at the upper part of the formed pattern.

[0032]

As described above, according to the present invention,
A resist film that causes eaves-like overhangs (in the case of a positive resist) and roundness at the top of the pattern (in the case of a negative type) that are observed when a resist pattern is formed using a conventional chemically amplified resist composition. It is possible to use a chemically amplified resist composition that can reduce the effect of acid consumption in the surface layer portion, and that is therefore excellent in resolution and capable of obtaining a good pattern shape.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/027 (72) Inventor Shuichi Miyata 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited

Claims (4)

[Claims] 1. A chemically amplified resist composition comprising two or more compounds that generate an acid upon irradiation with ionizing radiation or a compound that promotes the generation of an acid. 2. At least one of the compounds is a compound that substantially contributes to a reaction that changes the solubility of a resist film in a developing solution after irradiation with ionizing radiation, and the other compound substantially contributes to the reaction. The chemically amplified resist composition according to claim 1, wherein the chemically amplified resist composition is a compound that does not contribute to the physical property. 3. At least one of the compounds is a compound that substantially contributes to a reaction that changes the solubility of a resist film in a developing solution after irradiation with ionizing radiation, and other compounds than this compound are other compounds. The chemically amplified resist composition according to claim 1, wherein the compound is a compound that hardly contributes to the reaction. 4. The compound that generates an acid upon irradiation with ionizing radiation or the compound that promotes the generation of acid, which substantially contributes to a reaction that changes the solubility of a resist film in a developing solution after irradiation with ionizing radiation. The chemically amplified resist composition according to claim 1, characterized in that, in addition to the compound, it contains a compound that is less likely to contribute to the reaction than the compound and a compound that does not substantially contribute to the reaction. object.