JPH11305437A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove only a resist while suppressing damages on a base body by heating the resist film to a temp. higher than the decomposition temp. of a dissolution inhibiting group or dissolution inhibitor in the resist film and dipping the resist in a soln. which dissolves the resist to remove the resist film. SOLUTION: An org. antireflection film 3 is applied on a base substrate 1 where a pattern 2 is formed (a). Then a chemically amplifying positive resist film 4 having t-butoxycarbonyl group as a dissolution inhibiting group is formed (b). The film is exposed to KrF excimer laser beam 5 through an exposure mask 6 (c) and developed with a TMAH aq. soln. to form a resist pattern 4. When misalignment is caused in this process, the treated substrate 1 is baked on a hot plate, for example, at 160 deg.C for 60 sec, and dipped in a TMAH aq. soln. to remove the resist pattern 4. Since the dissolution inhibiting group is decomposed by heating and dissolved in the TMAH aq. soln., the base antireflection film 3 is not influenced.

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, and more particularly, to a pattern forming method using an anti-reflection film in manufacturing a semiconductor device.

[0002]

2. Description of the Related Art A method of manufacturing a semiconductor device includes many steps of depositing a plurality of substances on a wafer and patterning the same into a desired pattern. This patterning step
A process of depositing a photosensitive material generally called a resist on a film to be processed on a semiconductor wafer and selectively exposing the resist to a pattern using ultraviolet light as a light source is involved.

In such a pattern exposure process,
It is important to prevent exposure light from being reflected from the film to be processed, and a method of forming an antireflection film between a resist and a film to be processed as disclosed in Japanese Patent Application Laid-Open No. 49-55280. Has been proposed. Various materials are used for the antireflection film, and materials that can be applied by a spin coating method with low process cost as described below are mainly used.

[0004] 1) Plasma decomposition type resin such as polysulfone (Japanese Patent Application Laid-Open No. 58-149045) 2) Polysilane (US Pat. No. 5,380,621, Japanese Patent Application Laid-Open No. 5-257288) However, these materials include: There are the following problems.

That is, in the case of the material 1), when the resist pattern is transferred by the dry etching method, the etching rates of the anti-reflection film and the resist are substantially equal, so that the resist pattern completely disappears during the etching of the anti-reflection film. It is difficult to process the antireflection film with the dimensions described above. In particular, when the thickness of the resist is reduced to the same level as that of the anti-reflection film in order to enhance the resolution, this problem becomes more remarkable.

The material 2) has the advantage that the etching rate of the anti-reflection film is higher than that of the resist, but residue is generated when the anti-reflection film is peeled off after processing the film to be processed. Alternatively, if the peeling treatment is performed in a state where no residue is generated, the film to be processed is also shaved at the same time.

As the material 2), an organic silicon compound having a main chain of silicon and silicon such as polysilane has been known so far. As a pattern forming method using an organic silicon film containing such an organic silicon compound as an antireflection film, first, a resist pattern is formed, and then, using the resist pattern as a mask, a resist pattern is formed on the organic silicon film. A process is known in which a transferred film is patterned using a transferred organic silicon film pattern as a mask, and then the resist pattern and the organic silicon film pattern are separated.

According to such a pattern forming method, an organic silicon film such as polysilane can be peeled off without generating a residue.

However, in the actual pattern forming process, a mistake may occur in a part of the process due to some device trouble or the like. A typical example is a mistake in forming a resist pattern. For example, a desired pattern may not be formed due to, for example, insufficient exposure or a shift in focus position. In addition, a misalignment may cause a displacement between a pattern of a film (already formed) under the film to be processed and a resist pattern formed by this process.

In the case where the formation of the resist pattern has failed, the resist pattern which has already been formed is removed, a new resist film is formed again, and exposure and development are performed.
It is necessary to re-form the resist pattern. Also, at the stage of applying the resist, due to uneven coating of the resist, etc.,
It may be necessary to apply the resist again. In such a case, it is necessary to remove the resist film or the resist pattern. In a process using an organic silicon film as an antireflection film, conventionally, a mixed plasma of oxygen and CF ₄ has been used to remove the resist. Then, the resist film and the organic silicon film are simultaneously peeled off, and thereafter, an organic silicon film is formed on the film to be processed, a resist film is formed thereon, and exposure and development are performed to re-form the resist pattern. However, this process involves the following 2
There are two disadvantages.

1) Since the organic silicon film is also removed when the resist is removed, it is necessary to apply the organic silicon film again, which increases the process cost.

2) When the organic silicon film is formed again after the removal of the organic silicon film, the adhesion between the film to be processed and the organic silicon film is deteriorated, and the organic silicon film is peeled off in some places.

Therefore, in the process of re-forming the resist pattern, there has been a demand for a process of removing only the resist pattern and leaving the organic silicon film as it is.

On the other hand, resist stripping in a semiconductor device manufacturing process has conventionally been carried out by a method of dissolving a resist using a mixed solution of a hydrogen peroxide solution and sulfuric acid, a method of dissolving using an organic solvent, and a method using an O ₂ asher. A method of incineration and the like are known. However, whichever method is used, the base substrate is considerably damaged.

For example, recently, for the purpose of reducing the reflection of exposure light from an underlying substrate, antireflection film technology has been studied. However, an organic coating type antireflection film (for example, Japanese Patent Application Laid-Open No. It is difficult to remove only the resist when using No. 149045). In the method described above,
Often, not only the resist but also the antireflection film is peeled off. This means that when misalignment or line width abnormality occurs during exposure, the resist is peeled off and re-applied, and when re-exposure is performed, the application is performed from the application of the antireflection film, which leads to an increase in the number of steps.

As semiconductor circuits become more highly integrated, specifications for alignment accuracy and dimensional accuracy become stricter, and inevitably the number of re-exposures must be increased. Therefore, it is necessary to easily remove only the resist.

[0017]

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and has as its object to provide a pattern forming method capable of efficiently removing only a resist while suppressing damage to a base.

[0018]

According to a first aspect of the present invention, a resist film is formed on a substrate to be processed, and the resist film is formed by dissolving a group or a dissolution inhibiting group in the resist film. A step of heating the resist film to a temperature not lower than a temperature at which the agent is decomposed, and a step of immersing the resist film in a solution for dissolving the resist to remove the resist film. I do.

According to a second aspect of the present invention, a step of forming a resist film on a substrate to be processed, a step of irradiating the resist film with radiation, heating, or a combination thereof are provided. Dipping the resist film in a solution for dissolution to remove the resist film.

According to a third aspect of the present invention, a step of forming an organic silicon film having a bond of silicon and silicon in a main chain on a substrate to be processed, and a step of forming a first resist pattern on the organic silicon film are provided. A solution containing at least one solvent selected from the group consisting of (a) a solvent contained in the resist solution, (b) a surfactant, and (c) an alkaline aqueous solution having a concentration higher than 0.20 N. A method for forming a pattern, comprising: a step of removing the first resist film by immersing the first resist pattern; and a step of forming a second resist pattern on the organic silicon film. I will provide a.

According to a fourth aspect of the present invention, a step of forming an organic silicon film having a bond of silicon and silicon in a main chain on a substrate to be processed; a step of forming a resist film on the organic silicon film; ) At least one solvent contained in the resist solution; (b) a surfactant;
Removing the resist film by immersing the resist film in a solution containing at least one selected from the group consisting of alkaline aqueous solutions having a concentration higher than 20 N, and forming a resist pattern on the organic silicon film And a step of forming a pattern.

Next, the first to fourth components configured as described above will be described.
The pattern forming method according to the present invention will be described in more detail.

First, the first and second aspects of the present invention will be described with reference to a currently mainstream chemically amplified resist as an example. As a general configuration example of a chemically amplified positive resist applied to KrF excimer laser exposure, a hydroxyl group of polyvinyl phenol is partially substituted with a t-butoxycarbonyl group or the like which is a dissolution inhibiting group, and an onium salt is used as an acid generator. There is a thing using. In such a resist, the dissolution inhibiting group or dissolution inhibitor is decomposed by the catalytic reaction of the acid generated in the exposed area, and becomes soluble in the alkaline developer.

As described above, the resist can be easily removed by using the basic property that the dissolution inhibiting group or the dissolution inhibiting agent is dissolved in an alkali developing solution when decomposed. That is, in the first invention, the decomposition of the dissolution-inhibiting group or the dissolution-inhibiting agent is performed by irradiation with ultraviolet rays, X-rays, an electron beam, an ion beam, or the like, or heat treatment, or a combination thereof. In this case, only the resist can be efficiently removed.

This is very effective for peeling off the resist at the time of re-exposure when a misalignment or dimensional abnormality or the like occurs in the resist pattern inspection after the exposure.

Further, the exposed resist film can be more simply peeled off after being exposed and developed on the entire surface. However, the first invention can be easily applied to a non-chemically amplified naphthoquinone / novolak type positive resist. However, in the case of a chemically amplified resist, depending on the type of resist, impurities are present in a film once developed. It may hinder the acid-catalyzed reaction at the time of overall exposure, making it difficult to remove with a developer. In such a case, it is better to apply the above-described decomposition of the dissolution inhibiting group or dissolution inhibitor by heating.

In the first invention, the resist film is heated to a temperature higher than a temperature at which the dissolution inhibiting group or the dissolution inhibiting agent in the resist film is decomposed. That is, when the chemically amplified positive resist is stripped, first, the resist is heated at a temperature higher than the temperature at which the dissolution inhibiting group or the dissolution inhibitor is decomposed, and then dissolved with an alkali solution. It is known that a dissolution inhibiting group or a dissolution inhibitor of a chemically amplified positive resist is decomposed by heating or the like in addition to a catalytic reaction by an acid. Therefore, even when an organic antireflection film or the like is used as the lower layer, only the resist can be peeled off by decomposing the dissolution inhibiting group or dissolution inhibitor in the resist by heating and immersing the resist in an alkaline solution.

FIG. 6 shows a film thickness 60 formed on a Si substrate.
00 Å chemically amplified positive resist (using t-butoxycarbonylmethyl group as dissolution inhibiting group)
3 shows the heating temperature dependency (heating temperature of 60 seconds) of the amount of the remaining resist film after dipping in a 0.21 normal TMAH aqueous solution for 60 seconds.

As can be seen from the graph of FIG. 6, by heating the resist film to 155 ° C. or higher, which is the decomposition temperature of the t-butoxycarbonylmethyl group as a dissolution inhibiting group, the residual film after development of the resist is reduced to 0 °. Becomes The result is 155
It shows that the dissolution inhibiting group was sufficiently decomposed at ℃. That is, in order to remove the resist, heating may be performed at a temperature higher than the temperature at which the dissolution inhibiting group is decomposed.

However, if the temperature is too high, a cross-linking reaction occurs between the polymer resins depending on the type of the resist, and the solubility in the developing solution may decrease. Therefore, it is necessary to check in advance the change in the melting characteristics with respect to the heating temperature.

In the second invention, the irradiation of the radiation
rF excimer laser (248 nm), ArF excimer laser (193 nm), i-line of mercury lamp (365 n)
m), high-energy rays such as electron beams and X-rays. The irradiation dose of radiation needs to be larger than the irradiation dose in normal exposure.

Although the heating temperature varies depending on the type of the resist, it is generally appropriate that the heating temperature is about 130 to 200 ° C.

As the solution for dissolving the resist used in the first and second inventions, an alkaline solution can be used. Examples of the alkali include inorganic alkalis such as sodium hydroxide, potassium hydroxide, ammonia and sodium silicate; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine; triethylamine and methyldiethylamine. And quaternary ammonium salts such as tetramethylammonium hydroxide (TMAH) and trimethylhydroxyethylammonium hydroxide.

In the first and second aspects of the invention, the substrate to be processed may be one having a film containing an organic compound or an organic silicon compound formed on the uppermost portion. As the organic silicon compound, polysilane described below can be used.

For example, it is generally difficult to remove only an organic compound used as an antireflection film or a resist film on an organic silicon film. This is because these organic compounds and the constituent materials of the organic silicon film are similar to the resist, and it is difficult to obtain a selective ratio between the resist and the lower organic film by the treatment with the organic solvent, the stripping solution, or the dry etching. .

On the other hand, in the first and second inventions described above,
Since a reaction unique to the resist is used, only the resist can be efficiently stripped. Therefore, the first and second inventions are considered to be particularly effective for removing only the resist film on the organic compound or the organic silicon film.

In the third and fourth inventions, first, an organic silicon film containing an organic silicon compound having a bond of silicon and silicon as a main chain is formed as an antireflection film on a film to be processed on a silicon substrate. I do. That is, it is essential to form an organic silicon film as an antireflection film. Next, a resist solution is applied and baked on the organic silicon film to form a resist film. Next, the resist film is exposed and developed to form a resist pattern. On this occasion,
In some cases, it is necessary to re-form the resist pattern due to a failure in resist coating or exposure (third invention). Alternatively, the resist film may be removed at the stage when the resist film is formed because the uniformity of the film thickness is poor (fourth invention).

In these cases, in order to remove the resist film or the resist pattern, the film is formed by (a) at least one kind of solvent contained in the resist solution, (b) a surfactant, Impregnated with a solution containing one of high-concentration alkaline aqueous solutions, the resist was removed without removing the organic silicon film, and then the resist solution was applied and baked on the remaining organic silicon film again. Is formed, exposed and developed to form a resist pattern.

In the above third and fourth inventions, as a method of forming an organic silicon film, a method of forming an organic silicon film by a coating method will be described in detail here.

First, an organic silicon compound having silicon-silicon bonds in the main chain is dissolved in an organic solvent to prepare a solution material. Examples of the organic silicon compound having a silicon-silicon bond in the main chain include, for example, a compound represented by the general formula (S
iR ₁₁ R ₁₂ ) (wherein R ₁₁ and R ₁₂ represent a hydrogen atom or a substituted or unsubstituted aliphatic hydrocarbon having 1 to 20 carbon atoms or an aromatic hydrocarbon). Shown).

The polysilane may be a homopolymer or a copolymer, and may have a structure in which two or more polysilanes are bonded to each other via an oxygen atom, a nitrogen atom, an aliphatic group or an aromatic group. Specific examples of the organic silicon compound are shown in the following formulas [1-1] to [1-114]. In the formula, m,
n represents a positive integer.

The weight average molecular weight of these compounds is not particularly limited, but is preferably from 200 to 100,000. The reason is that if the molecular weight is less than 200, the organic silicon film is dissolved in the resist solvent, while
If it exceeds 000, it is difficult to dissolve in an organic solvent and it is difficult to prepare a solution material.

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The organic silicon compound is not limited to one kind, and several kinds of compounds may be mixed. In addition, if necessary, a thermal polymerization inhibitor for measuring storage stability, an adhesion enhancer for improving adhesion to the silicon-based insulating film, and a light reflected from the silicon-based insulating film into the resist film. Dye, polysulfone, which absorbs ultraviolet light to prevent
A polymer that absorbs ultraviolet light, such as polybenzimidazole, a conductive substance, a substance that becomes conductive by light or heat, or a crosslinking agent that can crosslink an organosilicon compound may be added.

Examples of the conductive substance include organic sulfonic acids, organic carboxylic acids, polyhydric alcohols, polyhydric thiols (for example, iodine and bromine), SbF ₅ , PF ₅ , B
F ₅ , SnF _{5 and the} like.

Examples of the substance that becomes conductive by energy such as light and heat include carbon clusters (C60 and C70), cyanoanthracene, dicyanoanthracene, triphenylpyrium, tetrafluoroborate, tetracyanoquinodimethane, and tetracyanoethylene. Phthalimide triflate, perchloropentacyclododecane, dicyanobenzene, benzonitrile, trichloromethyltriazine, benzoyl peroxide, benzophenonetetracarboxylic acid, t-butyl peroxide and the like.

More specifically, the following formulas [2-1] to [2]
-106].

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Examples of the cross-linking agent include an organic silicon compound having a multiple bond and an acrylic unsaturated compound. The solvent may be a polar organic solvent or a non-polar organic solvent. Specifically, ethyl lactate (EL),
Ethyl-3-ethoxypropionate (EEP), propylene glycol monomethyl ether acetate (PG
MEA), propylene glycol monomethyl ether (PGME), etc., cyclohexane, 2-heptanone,
Ketones such as 3-heptanone, acetylacetone, cyclopentanone, propylene glycol monoethyl ether acetate, ethyl cellosolve acetate, methyl cellosolve acetate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, methyl-3 -Esters such as ethoxypropionate, methyl pyruvate and ethyl pyruvate; ethers such as diethylene glycol dimethyl ether and propylene glycol dimethyl ether; methyl lactate; and ethyl glycolate derivatives such as ethyl glycolate, but are not limited thereto. It is not something to be done.

A coating material is prepared by the above method, and a solution material is applied on the silicon-based insulating film by, for example, a spin coating method, and then heated to evaporate the solvent.
Create an organic silicon film. At this stage, a glass transition temperature that can provide a sufficient selectivity to the resist may be obtained, but if it is not obtained, the coating film may be further heated or irradiated with an energy beam to crosslink the coating film. desirable.

Examples of the energy beam include ultraviolet light, X-rays, electron beams, and ion beams. In particular, simultaneous heating and irradiation with an energy beam can accelerate the progress of the crosslinking reaction and significantly improve the glass transition temperature in a practical process time. In addition, the bond between silicon and silicon in the main chain in the organic silicon compound having the bond between silicon and silicon in the main chain is expanded by heating or irradiation with an energy beam,
It combines with oxygen and is easily oxidized, and the etching selectivity between the resist and the silicon organic film is lowered.
In such a case, the heating and the irradiation with the energy beam are preferably performed in an atmosphere having a lower oxygen concentration than in air.

Next, a resist solution is applied on the organic silicon film and baked to form a resist film. As the resist at this time, for example, a resist containing a novolak resin and a naphthoquinone azide compound, an alkali-soluble resin, a compound whose alkali solubility is increased by an acid,
Examples thereof include, but are not limited to, a resist composed of a compound that generates an acid upon exposure, and a resist composed of a crosslinking agent and an alkali-soluble resin.

The resist may contain a dissolution inhibitor, a surfactant, a storage stabilizer and the like, if necessary. As a solvent contained in this resist, commonly used solvents include ethyl lactate (EL) and ethyl-3.
-Ethoxypropionate (EEP), propylene glycol monomethyl ether acetate (PGMEA),
Propylene glycol monomethyl ether (PGME)
And ketones such as cyclohexanone, 2-heptanone, 3-heptanone, acetylacetone, cyclopentanone, propylene glycol monoethyl ether acetate, ethyl cellosolve acetate, methyl cellosolve acetate, and methyl-3-methoxypropio. , Ethyl-3-methoxypropionate, methyl-3-ethoxypropionate, esters such as methyl pyruvate and ethyl pyruvate, ethers such as diethylene glycol dimethyl ether and propylene glycol dimethyl ether, methyl lactate and ethyl glycolate But are not limited thereto.

Next, the formed resist film is exposed and developed to form a resist pattern. In this case, a KrF excimer laser (248 n
m), an ArF excimer laser (193 nm), a high-energy ray such as an i-line (365 nm) of a mercury lamp, an electron beam, or an X-ray, but is not limited thereto.

When a desired resist pattern is not formed due to some process trouble, for example, a focus shift of an exposure device, it is necessary to remove only the resist pattern without removing the organic silicon film. Alternatively, if there is uneven application of the resist at the stage of applying the resist, before exposing the resist,
It is necessary to remove only the resist without removing the organic silicon film. In these cases, the following three methods can be used for removing the resist without removing the organic silicon film.

1) A resist pattern is impregnated with a solution containing at least one of the solvents contained in the resist solution,
The resist pattern is removed. The solution may contain a surfactant as shown in 2) below or an alkali solution as shown in 3) below.

2) The resist pattern is impregnated with a solution containing a surfactant. At this time, for example, a water-soluble organic solvent can be used. Examples of the water-soluble organic solvent include sulfoxides such as dimethyl sulfoxide having a hydrophobic alkyl group having 3 or more carbon atoms, sulfones such as dimethyl sulfone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide. Lactams such as N-methyl-2-pyrrolidone; polyhydric alcohols such as ethylene glycol, ethylene glycol monomethyl ether, and ethylene glycol monomethyl ether acetate, and derivatives thereof;

As the surfactant to be contained, any of generally known anionic, cationic and nonionic surfactants may be used. Specific examples of the surfactant include the following. First, as anionics, there are alkylbenzenesulfonic acids, alkylnaphthalenesulfonic acids and the like. As the cationic type, there is a quaternary ammonium salt having 6 or more carbon atoms. Examples of the nonionic type include polyoxyethylene fatty acid esters and polyoxyethylene alkyl ethers. The solution may contain an aqueous alkaline solution as shown in 3) below.

3) The resist pattern is impregnated with a high-concentration aqueous alkali solution. Examples of the alkali include inorganic alkalis such as sodium hydroxide, potassium hydroxide, ammonia and sodium silicate; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine; triethylamine and methyldiethylamine. And quaternary ammonium salts such as tetramethylammonium hydroxide (TMAH) and trimethylhydroxyethylammonium hydroxide. It is desirable that the concentration of the aqueous alkali solution is high, for example, in the case of TMAH, it is preferably 0.3 N or more.

The temperature of each of the above solutions may be room temperature, but may be heated to a temperature not exceeding 150 ° C. for the purpose of shortening the impregnation time.

After removing the resist pattern by any of the above 1) to 3), a resist solution is applied again,
Baking is performed to form a resist film, and exposure and development are performed to form a resist pattern. As a result, no peeling of the organic silicon film or the resist is observed, and a desired resist pattern is formed unless there is a trouble of the exposure apparatus as described above. If a desired resist pattern cannot be obtained again due to a trouble in the exposure apparatus, the process of removing the resist pattern, forming a resist film, exposing, and developing must be repeated. When a desired resist pattern is obtained, the pattern is transferred to the organic silicon film using the resist pattern as a mask. As a method of forming the pattern of the organic silicon film, for example,
Examples include a method of etching an organic silicon film using chlorine plasma, but the method is not limited thereto.

[0085]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 This embodiment is an embodiment according to the first invention.

As shown in FIG. 1A, a coating type organic anti-reflection film 3 (trade name: CD9: manufactured by Brewer Science) is formed on a base substrate 1 on which a first pattern 2 is formed.
It was applied to a thickness of 00 Å. Here, the material of the film constituting the first pattern 2 is not particularly limited as long as it is a conductor generally used for manufacturing an element. Further, the material of the antireflection film is not particularly limited.

Next, as shown in FIG. 1B, a chemically amplified positive resist having a t-butoxycarbonyl group as a dissolution inhibiting group was applied, and prebaked at 100 ° C. for 90 seconds to form a 6000 Å thick film. The resist film 4 was formed. Next, using a KrF excimer laser exposure apparatus NSR-S201A (manufactured by Nikon Corporation),
The excimer laser beam 5 was exposed through an exposure mask 6 having a second pattern.

Thereafter, a post-exposure bake (PEB) at 100 ° C. for 90 seconds is performed, developed with a 0.21 N aqueous solution of tetramethylammonium hydride (TMAH), and a resist pattern 4 is formed as shown in FIG. Was formed. However, since the misalignment occurred, the resist pattern 4 was peeled off by the following two methods. Method 1 is based on the present invention, and method 2 is based on the prior art.

(Method 1) First, as shown in FIG. 2A, the processing substrate 1 on which the resist pattern 4 was formed was baked on a hot plate 7 at 160 ° C. for 60 seconds. Next, 60 in a TMAH aqueous solution 8 of 0.21 normal
Then, the resist pattern 4 was removed as shown in FIG.

(Method 2) The treated substrate on which the resist pattern was formed was immersed in a mixed solution of hydrogen peroxide and sulfuric acid for 3 minutes to remove the resist pattern. The mixing ratio of the solution was set to 3 for sulfuric acid to 1 for aqueous hydrogen peroxide.

As described above, when the resist pattern was stripped by the methods 1 and 2, the following results were obtained.

According to the method 1, since the dissolution inhibiting group of the chemically amplified positive resist was decomposed by heating and dissolved in the TMAH aqueous solution, it was found that the underlayer antireflection film was not affected at all. On the other hand, in method 2, since a strong acid was used, the underlying organic antireflection film was also dissolved.

FIGS. 3 (a) and 3 (b) show the cross-sectional shapes of the resist patterns peeled off by the methods 1 and 2, respectively. From the comparison between FIG. 3A and FIG. 3B, in the method 2 of the prior art, the anti-reflection film is peeled off, and it is necessary to perform the anti-reflection film application again for the re-exposure. According to the method 1 of the present invention, only the resist pattern is peeled off, and it can be seen that it is only necessary to start over from resist application.

Embodiment 2 This embodiment is an embodiment according to the second invention.

In the same manner as in Example 1, a second pattern was formed on the first pattern. That is, as shown in FIG. 4A, a coating type organic antireflection film 10 was formed on a base substrate 12 on which a first pattern 9 was formed, and then a resist pattern 11 was formed thereon. .

Next, the resist pattern 11 was peeled off by the following methods 3 and 4. Method 3 is based on the present invention, and method 4 is based on the prior art.

(Method 3) First, as shown in FIG. 4B, the entire surface of the processing substrate 12 on which the resist pattern 11 was formed was exposed to a KrF excimer laser 13 by a KrF excimer exposure apparatus. Here, the exposure amount was twice as large as that during normal pattern exposure. Next, as shown in FIG. 4C, baking was performed at 110 ° C. for 90 seconds on a hot plate. Next, as shown in FIG.
The resist pattern 11 was removed by immersion in a 1N TMAH aqueous solution 15 for 60 seconds.

(Method 4) The treated substrate on which the resist pattern was formed was immersed in a mixed solution of a hydrogen peroxide solution and sulfuric acid for 3 minutes to remove the resist pattern. The mixing ratio of the solution was set to 3 for sulfuric acid with respect to 1 for hydrogen peroxide solution.

As described above, when the resist pattern was stripped by the methods 3 and 4, the following results were obtained.

According to the method 3, since the unexposed portion of the second pattern is re-exposed by the entire surface exposure, it has no influence on the underlying anti-reflection film. Further, since the exposure amount during the entire surface exposure is set higher than that during the normal pattern exposure, the resist can be made sufficiently soluble in an alkali developing solution or the like. On the other hand, in method 4, since a strong acid was used, the underlying organic antireflection film was also dissolved.

FIGS. 5A and 5B show the cross-sectional shapes of the resist patterns peeled off by the methods 3 and 4, respectively. From the comparison between FIG. 5 (a) and FIG. 5 (b),
In the method 4 of the prior art, the anti-reflection film is peeled off, and it is necessary to perform the anti-reflection film coating for re-exposure, whereas in the method 3 of the present invention, only the resist pattern is peeled off. It can be seen that it is sufficient to start over from resist application.

The following Examples 3 to 5 are examples according to the third invention.

Example 3 First, as shown in FIG. 7A, a weight average molecular weight of 12 represented by the above formula [1-84] was formed on an SiO ₂ film 22 having a thickness of 500 nm formed on a silicon substrate 21. A solution material prepared by dissolving 10 g of 2,000 organosilicon compounds (m / n = 4/1) in 90 g of toluene was applied by a spin coating method. Then, using a hot plate,
The solvent was vaporized and dried by heating at 60 ° C. for 90 seconds to form an organic silicon film 23 having a thickness of 0.15 μm.

Next, a resist solution was prepared by the following method. That is, about 40% of t-butoxycarbonylated polyvinylphenol 15 having an average molecular weight of 7,000
g, 1 g of triphenylfluphonium triflate was dissolved in 84 g of ethyl lactate, and filtered through a membrane filter having a pore size of 0.15 μm to obtain a photoresist solution.

Next, the above-mentioned photoresist solution was spin-coated on the above-mentioned organic silicon film 23 to a thickness of 0.8 μm and baked on a hot plate at 100 ° C. for 90 seconds.
A resist film 24 was formed (FIG. 7A).

Thereafter, the above resist is exposed using a KrF excimer stepper, and is exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
7 was formed (FIG. 7).
(B)).

Next, the resist pattern was impregnated with ethyl lactate at room temperature for 15 minutes to remove the resist pattern (FIG. 7C). When the surface of the remaining organic silicon film 23 was observed with an optical microscope and an electron microscope, no residue of the resist was observed, and no corrosion of the organic silicon film was observed at all.

Next, the above photoresist solution was spin-coated to a thickness of 0.8 μm on the remaining organic silicon film, and baked on a hot plate at 100 ° C. for 90 seconds.
A resist film 26 was formed (FIG. 7D).

Thereafter, the above resist was exposed using a KrF excimer stepper, and was exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
Was formed. When the pattern 27 was observed with an electron microscope, no peeling of the organic silicon film and no peeling of the resist film was observed, and no mixing between the resist and the organic silicon film was observed.
Was formed satisfactorily (FIG. 7E). The shape of the resist pattern 27 is the same as that of the resist pattern 2
As good as 5.

Comparative Example 1 First, as shown in FIG. 8A, on a SiO ₂ film 32 having a thickness of 500 nm formed on a silicon substrate 31, a weight average molecular weight of 12 represented by the above formula [1-84] was obtained. 2,000 organic silicon compounds (m / n = 4/1) in 90 g of toluene
The solution material prepared by dissolving in was coated by a spin coating method. Then, using a hot plate at 160 ° C.
For 90 seconds to evaporate and dry the solvent.
An organic silicon film 33 of 5 μm was formed.

Next, a resist solution was prepared by the following method. That is, about 40% of t-butoxycarbonylated polyvinylphenol 15 having an average molecular weight of 7,000
g and 1 g of triphenylfluphonium triflate were dissolved in 84 g of ethyl lactate, and filtered through a membrane filter having a pore size of 0.15 μm to obtain a photoresist solution.

Then, on the organic silicon film 33,
The photoresist solution was spin-coated to a thickness of 0.8 μm and baked on a hot plate at 100 ° C. for 90 seconds to form a resist film 34 (FIG. 8A).

Next, the resist film 34 is exposed to light using a KrF excimer stepper, and is exposed on a hot plate.
After baking at 00 ° C for 90 seconds, 0.21N TMA
H for 60 seconds to develop the resist with a width of 0.2
A 5 μm line and space pattern 35 was formed (FIG. 8B).

Next, the resist pattern 35 is changed to O ₂
1 for down-flow plasma using + CF ₄ mixed gas
Exposed for 0 minutes. The plasma conditions were O ₂ gas flow rate = 10
00 sccm, CF ₄ gas flow rate = 100 sccm, 20
This is a down flow plasma of 00 W, pressure 2 Torr, and temperature 200 ° C.

By exposing to such a down-flow plasma, the resist pattern 35 and the organic silicon film 33 were simultaneously removed (FIG. 8C). Remaining SiO ₂
No corrosion of the film 32 was observed, and no residue of the resist or the organic silicon film was observed.

Next, a solution material prepared by dissolving 10 g of an organic silicon compound having a weight average molecular weight of 12,000 represented by the above formula [1-1] in 90 g of toluene was applied to the remaining SiO ₂ film 32 by a spin coating method. Was applied. Next, the solvent was vaporized and dried by heating at 160 ° C. for 90 seconds using a hot plate to form an organic silicon film 36 having a thickness of 0.15 μm.

Thereafter, the above photoresist solution is spin-coated on the organic silicon film 36 to a thickness of 0.8 μm.
Baking was performed at 100 ° C. for 90 seconds on a hot plate to form a resist film 37 (FIG. 8D).

Thereafter, the above resist is exposed using a KrF excimer stepper, and is exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
Was formed. However, when the pattern was observed with an optical microscope and an electron microscope, it was found that the organic silicon
2, the resist pattern 38
Also peeled off as shown in FIG. 8 (e). Therefore, a part of the resist pattern 38 was not formed well.

Example 4 The same operation as in Example 3 was carried out by changing the types of the resist solution for forming the resist films 24 and 26, the film 22 to be processed, and the organic silicon film 23.
Solvent used for the removal of the resist pattern 2
The temperature was varied for the time of impregnation of 5.

The specific procedure is as follows.

First, in FIG. 7A, the following three types were formed as films 22 to be processed on a silicon substrate 21.

[0123] (A1): SiO ₂ film (A2) with a thickness of 500nm: SiO of 300nm, which was formed by the sputtering method ₂
TiN / Ti / 0.5% Cu-Al /
Metal wiring layer made of Ti / TiN (film thickness: 400 Å / 50 Å / 2300 Å / 100 Å / 200 Å) (A3): 390 nm thick polysilicon film formed on 500 nm thick SiO ₂ film The following two types of films were used as the organic silicon film 23 formed on the processed film 22.

(B1): An organosilicon compound having a weight average molecular weight of 12,000 represented by the above formula [1-84] (m / n
= 4/1) A solution material prepared by dissolving 10 g in 90 g of toluene is applied by a spin coating method, and then
An organic silicon film having a film thickness of 0.15 μm (B2), which was prepared by heating at 160 ° C. for 90 seconds using a hot plate to evaporate and dry the solvent, and having a weight average molecular weight of 1 represented by the above formula [1-84]
2,000 organosilicon compounds (m / n = 4/1) 1
A solution material prepared by dissolving 0 g and 0.1 g of fullerene in 90 g of toluene was applied by a spin coating method, and then heated at 160 ° C. for 90 seconds using a hot plate to evaporate and dry the solvent. Thickness 0.1
The following two types of resists 24 were used as the resist 24 on the 5 μm organic silicon film 23.

(C1): about 40% of t-butoxycarbonylated polyvinyl phenol having an average molecular weight of 7,000 (15 g), triphenylfluphonium triflate 1
g was dissolved in 84 g of ethyl lactate (EL), and the pore size was 0.15.
The solution was filtered through a μm membrane filter to obtain a photoresist solution. Next, on the above-mentioned organic silicon film 23,
The photoresist solution was spin-coated to a thickness of 0.8 μm, baked on a hot plate at 100 ° C. for 90 seconds,
A resist film 24 was formed.

(C2): 19 g of polyvinylphenol having an average molecular weight of 10,000 obtained by converting about 50% of t-butoxycarbonyl to 1.3 g of triphenylfluphonium triflate, 50 g of EL and ethyl-3-ethoxypropionate (EEP) ) Dissolved in 30 g of the mixed solution to give a pore size of 0.
The solution was filtered through a 15 μm membrane filter to obtain a photoresist solution. Next, the photoresist solution was spin-coated on the organic silicon film 23 to a thickness of 0.85 μm, and baked on a hot plate at 100 ° C. for 90 seconds to form a resist film 24.

After forming a laminated structure as shown in FIG. 7A as described above, the resist film 24 is exposed using a KrF excimer stepper and baked on a hot plate at 100 ° C. for 90 seconds. After that, development was performed for 60 seconds with 0.21 N TMAH to form a line and space pattern 25 having a width of 0.25 μm of the resist (FIG. 7B).

Next, the resist pattern 25 was impregnated with an organic solvent to remove the resist pattern 25 (FIG. 7).
(C)). The type, temperature, and time of the organic solvent were changed as shown in Table 1 below.

The surface of the remaining organic silicon film 23 was observed with an optical microscope and an electron microscope, and it was examined whether there was any remaining resist and whether the organic silicon film was corroded. The results are shown in Table 2 below. From Table 2 below, it can be seen that the resist can be removed without generating a resist residue. In addition, in all cases of “O” in Table 2, there was no corrosion to the organic silicon film.

[0130]

[Table 1]

[0131]

[Table 2]

Next, the following operation was performed on the organic silicon film having no residue.

A resist film 26 was formed on the remaining organic silicon film 23 using the same photoresist solution and the same processing conditions as those used when forming the resist film 24 (FIG. 2D).

Thereafter, the above resist was exposed using a KrF excimer stepper, and was exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
The line and space pattern 27 of FIG.
(E)).

The results of observing the pattern with an electron microscope and observing the presence or absence of peeling of the organic silicon film are shown in Table 3 below. In Table 3 below, in the case where the result was “○”, the resist film was not peeled off, and no mixing between the resist and the organic silicon film was observed, and the 0.25 μm line and space pattern 27 was formed favorably. Thus, the shape of the resist pattern 27 was as good as that of the resist pattern 25 before the resist was re-applied.

[0136]

[Table 3]

Comparative Example 2 The same operation as in Comparative Example 1 was performed by changing the types of the resist solution for forming the resist films 34 and 37, the film 32 to be processed, and the organic silicon films 33 and 36. And the processing conditions for removing the organic silicon film were changed.

The specific procedure is as follows.

First, in FIG. 8A, the film to be processed 32 on the silicon substrate 31 is the same as (A1) to (A1) of the fourth embodiment.
(A3) was used. Next, as the organic silicon film 33 formed on the film to be processed 32, (B1) and (B
2) was used. As the resist 34 on the organic silicon film 33, (C1) and (C2) of Example 4 were used.

After forming a laminated structure as shown in FIG. 8A as described above, the above resist is exposed using a KrF excimer stepper, and the resist is exposed to a hot plate.
After baking at 90 ° C. for 90 seconds, development was performed with 0.21 N TMAH for 60 seconds to obtain a resist having a width of 0.25 μm.
An m line and space pattern 35 was formed (FIG. 8B).

[0141] Next, the resist pattern 35, O ₂
The substrate was exposed to down-flow plasma using a mixed gas of + CF ₄ . The plasma conditions were changed as in the following (E1) to (E4), and the resist pattern 35 and the organic silicon film 33 were simultaneously removed.

(E1): O ₂ flow rate = 1000 sccm,
CF ₄ flow rate = 100 sccm, 2000 W, pressure 2 To
rr, temperature 200 ° C., 10 min (E2): O ₂ flow rate = 1000 sccm, CF ₄ flow rate =
20 sccm, 2000 W, pressure 2 Torr, temperature 20
0 ° C., 10 min (E3): O ₂ flow rate = 1000 sccm, CF ₄ flow rate =
100 sccm, 2000 W, pressure 2 Torr, temperature is room temperature, 10 min (E4): O ₂ flow rate = 1000 sccm, CF ₄ flow rate =
After exposing the resist pattern 35 to plasma at 20 sccm, 2000 W, a pressure of 2 Torr, and a temperature of room temperature for 10 min or more, it was observed whether or not residues were found on the film 32 to be processed. The results are shown in Table 4 below. In addition, the result is "○"
No corrosion of the film to be processed 32 was observed.

[0143]

[Table 4]

Next, in the case where no residue was found on the film to be processed as described above, an organic silicon film 36 was formed under the same solution and processing conditions as those used for forming the organic silicon film 33. The resist film 37 was formed under the same solution and processing conditions as those used for forming the resist film 34. FIG.
(D)).

Thereafter, the resist film 37 is exposed to light using a KrF excimer stepper, and is exposed on a hot plate for 1 hour.
After baking at 00 ° C for 90 seconds, 0.21N TMA
H for 60 seconds to develop the resist with a width of 0.2
A 5 μm line and space pattern 38 was formed (FIG. 8E).

The pattern 38 was observed with an electron microscope, and the presence or absence of peeling of the organic silicon film 36 was observed. The results are shown in Table 5 below. As can be seen from Table 5 below, under all conditions, peeling of the organic silicon film 36 from the film 32 to be processed was observed, so that the resist pattern 38 also peeled off as shown in FIG. As a result, a part of the pattern 38 was not formed.

[0147]

[Table 5]

Example 5 First, as shown in FIG. 7A, a film to be processed 22 formed on a silicon substrate 21 was used in Example 4 (A
1) to (A3) were formed. Next, an organic silicon film 23 was formed on the processing target film 22. As the organic silicon film, (B1) and (B1) used in Example 4 were used.
Two types of 2) were used.

Next, a resist film 24 was formed on the organic silicon film 23. Example 4 was used as the resist film 24.
(C1) and (C2) were used.

As described above, after forming a laminated structure as shown in FIG. 7A, the above resist is exposed using a KrF excimer stepper, and is exposed on a hot plate.
After baking at 0 ° C for 90 seconds, 0.21N TMAH
Developing for 60 seconds, the width of the resist is 0.25
A μm line and space pattern 25 was formed (FIG. 7B).

Next, the resist pattern 25 was impregnated with a solution containing a surfactant or an alkali developing solution having a changed concentration. The composition, solution temperature and time at that time were changed from (F1) to (F12) in Table 6 below.

[0152]

[Table 6]

The surface of the remaining organic silicon film 23 was observed with an optical microscope and an electron microscope, and the presence or absence of a resist residue was examined. The results are shown in Table 7 below. In Table 7, in all cases where the result was “O”, that is, there was no resist residue, no corrosion of the organic silicon film was observed at all.

[0154]

[Table 7]

Next, for those having a result of “○” in Table 7 above, the above photoresist solution was spin-coated to a thickness of 0.8 μm on the remaining organic silicon film, and 100 μm thick on a hot plate. Baking was performed at 90 ° C. for 90 seconds to form a resist film 26 (FIG. 7D).

Thereafter, the above resist was exposed using a KrF excimer stepper, and was exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
Was formed. When the pattern 25 was observed with an electron microscope, no peeling of the organic silicon film and no peeling of the resist film was observed, and no mixing between the resist and the organic silicon film was observed.
Was formed satisfactorily (FIG. 7E).

The shape of the resist pattern 27 was as good as that of the resist pattern 25 before the resist was re-applied.

Embodiment 6 This embodiment is an embodiment according to the fourth invention.

First, as shown in FIG. 9A, a film to be processed 42 formed on a silicon
(A1) to (A3) were used. Next, an organic silicon film 43 was formed on the processed film 42.
The organic silicon film 43 used in Example 4 (B
Two types 1) and (B2) were used.

Next, a resist film 44 was formed on the organic silicon film 43. As the resist film, two types (C1) and (C2) used in Example 4 were used.

After forming a laminated structure as shown in FIG. 9A as described above, the resist film is converted into a solvent containing the resist, a solution containing a surfactant, or an alkali developing solution having a changed concentration. Impregnated. Then, the surface of the remaining organic silicon film 43 was observed with an optical microscope and an electron microscope, and the presence or absence of a resist residue was examined. Table 8 below shows the composition of the impregnated solution, the impregnation conditions, and the results of evaluating the presence or absence of the residue. In Table 8 below, the result was "O", that is, for all the samples having no resist residue, no corrosion of the organic silicon film was observed at all (FIG. 9B).

[0162]

[Table 8]

Next, for those having a result of “○” in Table 8, the above-mentioned photoresist solution was spin-coated to a thickness of 0.8 μm on the remaining organic silicon film, and 100 μm on a hot plate. Baking was performed at 90 ° C. for 90 seconds to form a resist film 45 (FIG. 9C).

Thereafter, the above resist was exposed using a KrF excimer stepper, and was exposed to a hot plate at 100 ° C.
After baking for 90 seconds at,
After developing for 0 seconds, the width of the resist is 0.25 μm.
Was formed. When the pattern 46 was observed with an electron microscope, no peeling of the organic silicon film and no peeling of the resist film were observed, and no mixing between the resist and the organic silicon film was observed.
Was formed satisfactorily (FIG. 9D).

[0165]

As described above, according to the first and second aspects of the present invention, resist dissolution is inhibited by irradiation with ultraviolet light, X-ray, electron beam, ion beam, or the like, or by heat treatment, or a combination thereof. By decomposing the group and treating with an alkali developer or the like, only the resist can be efficiently removed. This is particularly effective for removing the resist at the time of re-exposure when misalignment or dimensional abnormality occurs in the inspection of the resist pattern after exposure.

According to the third and fourth aspects of the present invention, when the resist pattern or the resist film is removed, only the resist pattern or the resist film is removed, and then only the resist is re-applied. Is formed, a desired resist pattern can be obtained without peeling of the organic silicon film.

At this time, there is no peeling of the resist film and no mixing of the resist with the underlayer, for example, the organic silicon film. In addition, when the method of the present invention is used, it is not necessary to recoat the organic silicon film, so that the process cost is reduced as compared with the case where both the resist film and the organic silicon film are removed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pattern forming method according to a first embodiment in the order of steps.

FIG. 2 is a sectional view showing a pattern forming method according to the first embodiment in the order of steps.

FIG. 3 is a cross-sectional view showing a structure after a resist pattern is stripped by a method according to the first embodiment and a conventional method.

FIG. 4 is a sectional view illustrating a pattern forming method according to a second embodiment in the order of steps;

FIG. 5 is a cross-sectional view showing a structure after a resist pattern is stripped by a method according to the second embodiment and a conventional method.

FIG. 6 is a characteristic diagram showing the heating temperature dependence of a resist residue.

FIG. 7 is a sectional view illustrating a pattern forming method according to a third embodiment in the order of steps.

FIG. 8 is a sectional view showing a pattern forming method according to Comparative Example 1 in the order of steps.

FIG. 9 is a sectional view showing a pattern forming method according to Example 6 in the order of steps.

[Explanation of symbols]

1, 12, 21, 31, 41, silicon substrate 2, 9 pattern 3, 10, 23, 33, 43 antireflection film 4, 24, 26, 34, 37, 44, 45 ... resist film 4, 9, 25, 27, 35, 38, 46 ... resist pattern

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 572B 574

Claims (7)

[Claims] A step of forming a resist film on a substrate to be processed; a step of heating the resist film to a temperature equal to or higher than a temperature at which a dissolution inhibiting group or a dissolution inhibitor in the resist film is decomposed; Immersing the resist film in a solution for dissolving the resist to remove the resist film. A step of forming a resist film on the substrate to be processed; a step of irradiating the resist film with radiation, heating, or a combination thereof; and converting the resist film into a solution for dissolving the resist. Dipping the resist film to remove the resist film. 3. The pattern forming method according to claim 1, wherein an alkaline solution is used as a solution for dissolving the resist. 4. The substrate to be processed according to claim 1, wherein a film containing an organic silicon compound having a silicon-to-silicon bond in its main chain is formed on the uppermost portion. The pattern forming method according to any of the above items. 5. The pattern forming method according to claim 1, wherein said resist is a chemically amplified positive resist. 6. A step of forming an organic silicon film having a bond between silicon and silicon in a main chain on a substrate to be processed; a step of forming a first resist pattern on the organic silicon film; The first solution is added to a solution containing at least one kind of solvent contained in the resist solution, (b) a surfactant, and (c) at least one kind selected from the group consisting of an aqueous alkali solution having a concentration higher than 0.20 N. A pattern forming method, comprising: a step of removing the first resist pattern by immersing the resist pattern; and a step of forming a second resist pattern on the organic silicon film. 7. A step of forming an organic silicon film having a bond between silicon and silicon in a main chain on a substrate to be processed, a step of forming a resist film on the organic silicon film, (a) the resist solution Dipping the resist film in a solution containing at least one solvent selected from the group consisting of: (b) a surfactant, and (c) an alkaline aqueous solution having a concentration higher than 0.20 N. A pattern forming method, comprising: a step of removing the resist film by using the method described above; and a step of forming a resist pattern on the organic silicon film.