JPH09258451A - Photosensitive resin film pattern forming method and production of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a satisfactory resist pattern by incorporating a 1st substance generating radicals by exposure and a 2nd substance acting as a radical capturing agent into an org. film. SOLUTION: An org. film and a photosensitive resin film are successively formed on a body to be worked and the resin film is selectively exposed and developed to form a photosensitive resin film pattern. The org. film contains a 1st substance generating radicals by exposure and a 2nd substance acting as a radical capturing agent. The 1st substance is e.g. an org. substance having alkene, alkyne, carbonyl, aldehyde, carboxyl, ester, thiocarbonly, amido, azomethine, nitrile, azo, nitroso, nitric acid, nitro, nitrous acid or sulfone group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a photosensitive resin film pattern, and a method for manufacturing a semiconductor device using a resist pattern formed by this method.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, many steps of depositing a plurality of substances on a silicon wafer and patterning them into a desired pattern are included. This patterning process is usually performed as follows. First, a photoresist film is formed on an insulator, a conductor, and a semiconductor thin film formed on a silicon wafer by a spin coating method or the like, and then the photoresist is selectively exposed, and then a resist pattern is formed through a developing process. . Next, using the resist pattern as an etching mask, the insulators, conductors, and semiconductor thin films that are workpieces formed on the substrate are etched to form fine wiring, openings, etc. into a desired pattern.

As the resist material, an appropriate one is selected depending on the exposure light source, the size of the resist pattern, etc., and the i-line (λ = 365 nm) of a high pressure mercury lamp or the KrF excimer laser light (λ = 248 nm) is used as the exposure light source. For example, a diazonaphthoquinone-based resist containing orthodiazonaphthoquinone-5-sulfonic acid ester and a novolac resin, a chemically amplified resist using an acid catalyst reaction, or the like is used.

In a diazonaphthoquinone type resist, when a novolak resin and an orthodiazonaphthoquinone sulfonic acid ester are mixed, they are not dissolved in an alkaline developing solution,
When light is irradiated, a carboxylic acid is generated from orthodiazonaphthoquinone sulfonic acid ester, and only the light-irradiated portion is selectively dissolved in an alkali developing solution.
In the case of chemically amplified resists, acid is generated when the acid generator is irradiated with light, and the resin undergoes a crosslinking reaction using the acid as a catalyst or the polymer is modified to select the solubility of the exposed portion in the developer. It takes advantage of the changing nature.

Further, the shape of the resist pattern can be qualitatively predicted by computer simulation in consideration of an optical image formed in the resist film at the time of exposure and a chemical reaction occurring in the resist film. For example, such a calculation method is based on the Polymer Mate.
rias for Microelectronics
s Applications, Chapter1
4, pp. 176-184, Amer. Chem. So
c. , Washington, DC, 1994. Etc.

In such a patterning process,
It is important to control the dimensions of the resist pattern with high accuracy, but in the process of forming a pattern on a substrate that has a high reflectance for exposure light, it is locally affected by the action of the reflected light from the stepped portion of the substrate. There is a possibility that the resist dimension varies and the profile deteriorates. Further, when a film made of silicon oxide or silicon nitride, which is relatively transparent to the exposure light, is present immediately below the resist, the exposure light is multiply reflected in these films.

Therefore, if the film thickness of these films changes,
The behavior of the multiple reflection is affected. As a result, the amount of light energy applied to the resist layer substantially fluctuates, which seriously affects the controllability of the size of the resist pattern. Furthermore, since multiple reflection occurs even in the resist film, if the resist film thickness fluctuates, it also has a great influence on the pattern size fluctuation.

The swing ratio S indicating the magnitude of multiple reflections generated in the resist film is T. A. Bruner SP
IE vol. 1466 Proc. 1466,229
7 (1991) and the like, the reflectance at the interface between the resist and air is R ₁ , the reflectance at the interface between the resist and the antireflection film is R ₂ , the absorption coefficient of the resist is α, and the resist film is It is known that when the thickness is d, it is given by the following equation.

S = (R ₁ R ₂ ) ^1/2 exp (-αd) Therefore, in order to prevent the influence of multiple reflection, a dye is added to the resist, or a resin having a high absorptivity to the exposure wavelength is added as a component. The absorption coefficient α with respect to the exposure wavelength of the resist may be increased by using the above resist. Further, by forming an antireflection film between the resist and the substrate, the reflectance R
₂ may be lowered.

In the method of forming the antireflection film, the light reflected at the interface between the substrate and the antireflection film and the light reflected at the interface between the resist and the antireflection film absorb the exposure light by the antireflection film and invert the phase. By canceling with, the intensity of the light reflected on the resist layer can be remarkably weakened. As a result, it is possible to reduce the dimensional fluctuation of the resist pattern and the deterioration of the profile due to the reflection of the exposure light from the step of the substrate and the fluctuation of the resist film thickness.

Various types of antireflection films have been proposed, but among them, a method of forming an antireflection film made of an organic thin film on a substrate by a spin coating method is often used. Examples of the organic thin film include, for example, JP-A-59-93.
As disclosed in Japanese Laid-Open Patent Publication No. 448, the one using a resin that absorbs exposure light, or the one in which a dye having a property of absorbing exposure light, for example, curcumin or coumarin is dispersed in a resin is often used. There is.

[0012]

However, in the above-mentioned organic antireflection film, the resin contained therein may be deteriorated by irradiation of ultraviolet rays. In particular, with the recent miniaturization of patterns, the exposure light having a shorter wavelength D than before has been used.
This effect has become particularly pronounced when UV light has come to be used because DUV light is high-energy light.

Deterioration of the resin contained in the antireflection film causes breakage of the main chain of the resin. Therefore, the molecular weight of the resin is lowered and a large number of decomposition products having chemically active properties are produced. The lower molecular weight of the resin causes mixing of the resist and the antireflection film in a heat step after exposure, etc., and the mixed layer becomes difficult to dissolve in the developing solution, and as shown in FIG. 15 (a), Resist pattern 4
The lower part of 3 is shaped like a hem. In the figure, reference numeral 41 is a patterning film which is a base, and 42 is an antireflection film.

Further, in an antireflection film having a (co) polymer of an amine acid or sulfur dioxide as disclosed in JP-A-59-93448, these polymer main chains cause photodecomposition during exposure. When it occurs, in the case of an antireflection film made of a (co) polymer of an amine acid, for example, in the case of an antireflection film made of a decomposition product having an amino group or an imino group, or in the case of an antireflection film made of a (co) polymer of sulfur dioxide, , Sulfonic acid is generated.
Since these basic and acidic decomposition products have small molecular weights, they easily diffuse into the resist layer by the heat step after exposure.

When the resist used in the upper layer is a chemically amplified resist utilizing an acid catalyst reaction, these basic or acidic decomposition products cause deterioration of the resolution and cross-sectional shape of the resist. Will end up. That is, since the above basic decomposed product becomes a catalyst poison for the acid-catalyzed reaction, for example, in the case of a positive type resist, the portion near the interface of the antireflection film of the resist is against the developer like the unexposed portion. It becomes insoluble, and as shown in FIG. 15A, the resist pattern 43 has a skirted shape, or in the worst case, the patterns are connected to each other.

On the other hand, an acidic decomposed product causes an excessive acid-catalyzed reaction in the vicinity of the interface between the resist 43 and the antireflection film 42. Therefore, as shown in FIG. 15B, for example, in the case of a positive resist. Causes an undercut at the bottom of the resist, and in a worse case, a defect such as tilting, peeling, or flying of the resist pattern occurs.

The resist used for the upper layer is
In the case of a chemically amplified resist that utilizes an acid-catalyzed reaction, part of the energy is transferred from the polymer in the antireflection film excited during exposure to the acid generator in the resist, The phenomenon of acid generation occurs. Therefore, it causes an excessive catalytic reaction in the vicinity of the interface between the resist and the antireflection film. For example, in the case of a positive type resist, an undercut occurs at the bottom of the resist, and in a worse case, the resist pattern collapses, peels, or jumps. Occurs.

Deterioration of the shape of the resist pattern is also caused by the following causes. That is, (1) to
In the case of (3), the light intensity is remarkably attenuated toward the resist lower layer portion in the thickness direction of the resist.

(1) When a resist having high absorptivity for exposure light is used to suppress multiple reflections occurring in the resist film, (2) a resist material having a low transmittance for the exposure wavelength is used. When used, (3) when an antireflection film is formed between the resist and the workpiece, and the intensity of light re-incident on the resist at the interface between the resist and the antireflection film is strongly attenuated.

In the above cases (1), (2) and (3),
Since the light intensity of the lower layer portion of the resist is weaker than that of the upper layer portion, the taper shape as shown in FIG. 16A is used when the positive resist is used, and the light intensity of the negative resist is used as shown in FIG. 16B when the negative resist is used. A reverse taper shape as shown in is obtained.

In addition to optical factors, resist component distribution occurs in the resist film thickness direction, the solubility of the resist in the lower layer and the upper layer is different from that in the developing solution, and the antireflection film and the resist are mixed. The deterioration of the resist profile also occurs due to the fact that it becomes difficult to dissolve in the developing solution.

When these abnormalities occur in the resist pattern, not only the controllability of the pattern size is significantly deteriorated when the underlayer is processed by dry etching or the like using this as a mask, but also the exposure margin, focus margin, etc. Also, the process margin of No. 1 is significantly reduced, and the yield is significantly reduced.

It is an object of the present invention to provide a method for forming a good resist pattern by using an organic film which does not cause photodegradation of resin which causes the above problems.

Another object of the present invention is to provide a method for forming a resist pattern having a good shape by changing the solubility of the resist by a photochemical reaction between the organic film and the resist.

Still another object of the present invention is to provide a method for manufacturing a semiconductor device with high accuracy using the above resist pattern.

[0026]

The present invention has been made in view of the above problems. In the first aspect, a predetermined organic film is used to prevent photodegradation of the organic film.

That is, the present invention (Claim 1) comprises a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective step. And a step of developing a photosensitive resin film pattern exposed to light to form a photosensitive resin film pattern. A method for forming a photosensitive resin film pattern, which comprises a second substance acting as a radical scavenger.

According to the present invention (claim 2), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective exposure. And developing a photosensitive resin film pattern to form a photosensitive resin film pattern, wherein the organic film includes a first substance excited by the exposure and a first substance. A method for forming a photosensitive resin film pattern, which comprises a second substance acting as a quencher.

According to the present invention (claim 3), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective exposure. And developing a photosensitive resin film pattern to form a photosensitive resin film pattern, wherein the organic film comprises a benzophenone compound, a salicylate compound, a benzotriazole compound, an acrylate compound, and a methacrylic acid film. A method for forming a photosensitive resin film pattern, which comprises at least one selected from the group consisting of:

According to the present invention (claim 4), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective exposure. Developing the exposed photosensitive resin film to form a photosensitive resin film pattern, wherein the organic film comprises a first substance that generates an acidic or basic decomposition product upon exposure and the acidic substance. Alternatively, the present invention provides a method for forming a photosensitive resin film pattern, which comprises a second substance that neutralizes a basic decomposition product.

Further, in the second aspect of the present invention, the solubility of the resist is changed by a photochemical reaction between the organic film and the resist to obtain a photosensitive resin film pattern having a desired shape.

That is, according to the present invention (claim 5), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective step The step of developing the exposed photosensitive resin film to form a photosensitive resin film pattern, the organic film is decomposed by the exposure, and the decomposed product is diffused in the photosensitive resin film. Accordingly, there is provided a method for forming a photosensitive resin film pattern, which comprises a substance that changes the solubility of the photosensitive resin film during the development.

According to the present invention (claim 6), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective exposure. Developing the photosensitive resin film, and forming a pattern of the photosensitive resin film, the organic film is a part of the energy supplied during the exposure from the molecules in the organic film to the photosensitive film. Provided is a method for forming a photosensitive resin film pattern, which comprises a substance that changes the solubility of the photosensitive resin film at the time of development by moving to a molecule in the photosensitive resin film.

According to the present invention (claim 7), a step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a selective exposure. The step of developing the exposed photosensitive resin film to form a photosensitive resin film pattern, wherein the organic film emits electrons from molecules in the organic film to molecules in the photosensitive resin film by the exposure. The present invention further provides a method for forming a photosensitive resin film pattern, wherein the photosensitive resin film contains a substance that changes the solubility of the photosensitive resin film during the development. 8) is a step of forming an object to be processed on a semiconductor substrate, and the method described above on the object to be processed (claim 1).
To 7), there is provided a method for manufacturing a semiconductor device, which comprises a step of forming a photosensitive resin film pattern, and a step of processing the object to be processed using the photosensitive resin film pattern.

Hereinafter, the details of the present invention and the action thereof will be described. In the first aspect of the present invention, a radical is generated by exposure, excited by exposure, and an acidic or basic decomposition product is generated by exposure. As the substance of alkene group,
Alkyne group, carbonyl group, aldehyde group, carboxyl group, ester group, thiocarbonyl group, amide group, azomethine group, nitrile group, azo group, nitroso group, nitric acid group,
An organic substance having a nitro group, a nitrite group, or a sulfone group can be given.

The content of the second substance in the organic film is
0.01 to 50% by weight is preferable, 0.1 to 30% by weight
Is particularly preferred. When the content of the second substance exceeds 50% by weight, the optical characteristics are deteriorated, and it becomes difficult to form a film on the wafer by the spin coating method.
If the amount is less than 01% by weight, the effect of adding the second substance cannot be expected.

As described above, the above-mentioned abnormalities in the resist profile and the mixing of the resist layer and the antireflection film are caused by the photodecomposition reaction of the polymer in the antireflection film during the pattern exposure, or the excited state. This is because the energy is transferred from the generated polymer to the acid generator in the resist. Therefore, it is possible to avoid the above problem by preventing such a reaction from occurring during pattern exposure.

In the photodecomposition reaction of the polymer, for example, the above-mentioned alkene group, alkyne group, carbonyl group, aldehyde group, carboxyl group, ester group, thiocarbonyl group, amide group, azomethine group of the substances constituting the antireflection film, A decomposition reaction occurs at a site that is easily excited by light, such as a nitrile group, an azo group, a nitroso group, a nitrate group, a nitro group, a nitrite group, or a sulfone group, and a free radical is generated at the decomposed main chain terminal. Further, the free radicals thus generated attack the undecomposed portion of the polymer in a chain reaction, and the decomposition reaction proceeds. Therefore, in order to prevent the photolysis reaction from proceeding, the following may be done.

(1) Prevent exposure light from penetrating into the polymer bulk which is prone to decomposition reaction.

(2) Functional groups excited by light are destroyed by energy transfer.

(3) The free radical generated by the decomposition of the polymer is destroyed by the radical scavenger.

In order to prevent a part of the exposure energy from being transferred from the polymer to the acid generator in the resist,
The following may be performed.

(4) Prevent exposure light from penetrating into the polymer bulk that easily transfers energy to the acid generator.

(5) The functional group excited by light is energy-transferred to another substance existing in the antireflection film to disintegrate it.

The above-mentioned principles of the photostabilization of the polymers (1) to (3) are as follows in the field of engineering plastics utilizing polymer bulk and the field of coating engineering.
It has been investigated in considerable detail as a method for suppressing the change over time when a polymer is exposed to natural white light in the atmosphere. However, natural white light is composed of light having various wavelength components, and in particular, it is focused on suppressing photodegradation with respect to ultraviolet rays of 300 nm or more, while in the present invention, it is used for an optical lithography process. The wavelength of light,
Specifically, the i-line of a high-pressure mercury lamp is 365 nm, the KrF excimer light is 248 nm, the ArF excimer light is 193 nm.
There is a big difference in that the stability with respect to light of each wavelength such as .. must be ensured. Therefore, depending on such a difference, it is necessary to use the optimum additive that brings about the above-mentioned effects (1) to (3).

In order to bring about the effects of (1) and (4), it is more preferable to use a low molecular weight ultraviolet absorber. Specific examples of the ultraviolet absorber include a benzophenone compound, a salicylate compound, a benzotriazole compound, an acrylate compound, and a methacrylate compound.

In order to bring about the actions (2) and (5), a series of substances called quenchers may be mixed. The quencher is a substance having a function of absorbing energy of a site in a polymer activated by photoexcitation, for example, a carbonyl group or a sulfone group, and causing it to collapse. Due to the quenching action of this substance, the excited part is relaxed to the stable state again, so that part of the energy is not transferred to the decomposition reaction and the acid generator, and the deterioration of the polymer and the change from the polymer to the acid generator occur Energy transfer can prevent the acid-catalyzed reaction from proceeding excessively near the interface with the antireflection film in the resist.

Examples of the compound having such an action include chelate compounds represented by the structural formulas (a) to (c) shown in the following chemical formula 1. Unlike the substance described in the action 1), this type of substance does not need to have the property of absorbing exposure light, and therefore adding this to the antireflection film does not change the optical properties of the antireflection film. Absent.

[0049]

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In order to bring about the action of (3),
A substance that reacts with the free radicals to dissociate them may be mixed in the antireflection film. A substance having such an action is called a radical scavenger, specifically, polyhydroxystyrene, or a phenol represented by the structural formulas (a) to (i) shown in Chemical formulas 2 and 3 below. Compounds, methylamine, ethylamine, trimethylamine, pipyridine, N-methylpyrrolidine, aniline, diphenylamine, N-methylaniline, benzamide,
Amino compounds such as acetanilide, pyrrole, pyridine, pyrimidine, purine, p-nitropropane, 2-
Mention may be made of nitro compounds such as nitrobutane.

[0051]

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[0052]

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These react with free radicals in the polymer generated by light irradiation to form relatively weakly active radicals. This weak radical does not have the activity of chain-cutting the polymer main chain, and thus has a function of suppressing photodegradation of the polymer. These are also (2) and (5)
Since it does not utilize the property of absorbing exposure light like the additive having the action of, it is possible to select a substance that does not absorb exposure light as the radical scavenger, for the purpose of increasing the effect of suppressing photodegradation, and thus the antireflection film. Even if a large amount of radical scavenger is added, the original performance of the antireflection film will not be deteriorated.

For example, taking lithography using KrF excimer light of 248 nm as an example, as a radical scavenger transparent to exposure light, 2,6-di-t-butylphenol or a trade name Ingoanox 1076 is commercially available. Octadecyl 3 (3,5-di-t-butyl-
4-hydroxyphenium) propionate and the like can be mentioned.

On the other hand, as a solution for the case where an acidic decomposition product is generated by the decomposition of the polymer in the antireflection film and an excessive acid catalytic reaction occurs near the interface between the resist and the antireflection film, resulting in deterioration of the resist profile. In addition to preventing the decomposition of the polymer, a basic substance may be added to the antireflection film to neutralize the acidic decomposition products. Neutralization in the antireflection film may prevent excessive acid-catalyzed reaction at the interface with the antireflection film.

On the contrary, when a basic decomposed product is produced, an acidic substance is added to the antireflection film to neutralize the basic decomposed product in the antireflection film to reflect the acid generated from the acid generator. It is sufficient to prevent the collapse at the interface with the prevention film.

As the substance which produces an acidic decomposition product, phenol compounds containing a carbonyl group or a sulfone group in the structural formula, and as the substance which produces a basic decomposition product,
Examples thereof include amino compounds and nitro compounds.

Next, the second aspect of the present invention will be described. The second aspect of the present invention utilizes the following three phenomena.

(1) A phenomenon in which the organic film undergoes a photolytic reaction upon irradiation with ultraviolet light, and as a result, the produced decomposition product diffuses into the resist film formed on the organic film, or is included in the organic film. The phenomenon that the acid generated from the generated acid generator diffuses in the resist film is used.

In the organic film formed between the resist and the object to be processed, the functional groups contained in the polymer when exposed to light, such as carbonyl group and sulfone group, are excited by light. A decomposition reaction occurs at an easy site, and a free radical is generated at the decomposed main chain terminal. Further, the generated free radicals attack the undecomposed portion of the polymer in a chain reaction, and the decomposition reaction proceeds. When the polymer contains acidic functional groups such as carbonyl groups and sulphone groups, acidic decomposed products are formed, and these decomposed products have a small molecular weight, so they were formed on top of the organic film. Easy to diffuse in resist.

When the resist is a positive type chemically amplified resist utilizing an acid catalyst reaction, the acidic decomposition product causes an acid catalyst reaction in the vicinity of the interface with the organic film. Therefore, even if the amount of exposure near the interface with the organic film is insufficient, it is possible to compensate for the shortage of acid generated from the acid generator and increase the solubility of the resist in the developer near the interface with the organic film. Become.

Further, in the case of a negative chemically amplified resist, an acidic decomposition product is generated from the organic film and diffused in the resist to promote an acid catalytic reaction in the vicinity of the interface with the organic film. It is possible to compensate for the insufficient amount of acid generated by the acid generator due to the insufficient amount, and improve the reverse taper shape.

On the other hand, the decomposed product in the present invention also includes an acid generated from the acid generator added to the organic film, and like the acid generated by the decomposition of the above-mentioned polymer, the resist near the interface is formed. It is possible to compensate for the lack of acid catalyzed reaction due to the optical image in the film.

As the acid generator, diallyl iodonium salt, triallyl sulfonium salt, 2,6-dinitrobenzilditosylate, p-nitrobenzyl-9,10-
Diethoxyanthracene-2-sulfonate, 2-
(4-methoxyphenyl) -4,6-di (trichloromethyl) triazine, orthodiazonaphthoquinone-4-sulfonic acid ester, orthodiazonaphthoquinone-5-
Examples of the sulfonic acid ester include, but are not particularly limited as long as an acid is generated by exposure light to change the dissolution characteristics of the resist.

As described above, the acidic decomposition product generated from the organic film by the photodecomposition reaction shows an acid-catalyzed reaction in the chemically amplified resist, but radicals generated by the decomposition of the organic film by the photodecomposition reaction, Alternatively, a method of forming a resist pattern in which the shape of the resist is controlled by the decomposition product entering the resist film and changing the solubility of the entering portion in the developing solution is also within the scope of the present invention.

(2) Utilizing light energy transfer occurring between molecules. There are three types of energy transfer, which are called a Forster type, a Dexter type, and a triplet sensitized type, depending on the method of transferring excitation energy, as shown below. When the molecule that gives energy is the donor molecule and the molecule that receives the energy is the acceptor molecule, 1) the acceptor molecule absorbs the emitted light in the process in which the donor molecule excited by the Forster type light irradiation returns to the ground state with the emission of light. Causes energy transfer.

2) Dexter type In a donor molecule in an excited state by light irradiation, electrons vibrate violently, forming an electric field equivalent to light as an electromagnetic wave, and other molecules in the vicinity thereof are affected by the vibration field. Receive. At this time, if the energy is just appropriate to excite the molecule, energy absorption equivalent to photon absorption occurs and energy transfer occurs.

3) Triplet-sensitized type The irradiation of light causes the donor molecule in the singlet excited state to relax to the triplet excited state, and an electron exchange interaction occurs with the triplet excited state of the acceptor molecule. , Energy transfer occurs.

Therefore, if the molecules existing in the organic film are used as the donor molecules and the molecules in the resist film are used as the acceptor molecules, the above 1) to 1) are used as the donor molecule and the acceptor molecule.
By selecting the molecule satisfying the condition of 3), a part of the energy supplied to the organic film at the time of exposure moves to the molecule in the resist film. The shape of the resist can be controlled by selecting an acceptor molecule such as an acid generator or a photosensitizer that changes the solubility characteristics of the resist in a developing solution.

Specifically, for example, when the acid generator contained in the resist film is a sulfonium salt or a sulfonimide, polysulfone, polyethersulfone, bisbenzyl sulfone, (2-methylsulfone) If any of benzyl) -phenyl sulfone, bis (naphthomethyl) sulfone, bis (3,4-dichlorobenzyl) sulfone, or bis (4-chlorobenzyl) sulfone is contained, such energy transfer is Remarkably occurs.

(3) It utilizes transfer of electrons occurring between molecules. In the excited state, one electron is packed in the lowest unoccupied orbital state, and the energy required to ionize from this state (see Fig. 1 (a)) is more likely to be ionized from the highest occupied orbital of the ground state. Required energy (Fig. 1
Since it is smaller than that in (b), the excited state is more likely to be a radical cation, and the photoexcited state has a higher electron donating property.

Also in the case of electron accepting property, if the electron jumps into the highest occupied orbital in which one electron is lost in the excited state, the energy obtained (see FIG. 2 (a)) is the lowest in the ground state. It is larger than the energy obtained when electrons jump into the orbit (see FIG. 2B). for that reason,
The excited state has a higher electron donating property and is more likely to be a radical anion. Therefore, when the molecule is excited to the excited state by light irradiation, the electron donating and electron accepting properties are increased as compared with the case where the molecule is in the ground state, and a highly reactive radical cation or radical anion is generated, A chemical reaction is likely to occur.

Here, if the electron-donating molecule is present in the organic film formed between the resist and the workpiece and the electron-donating molecule is present in the resist film, the above-mentioned electron transfer is caused. It can occur at the interface between the resist and the organic film,
The shape of the resist can be controlled by selecting a molecule that changes the solubility of the resist as a result of donating the electron as the electron-donating molecule.

Specifically, for example, when the electron-donating molecule contained in the resist film is one represented by the structural formulas 10 to 12 shown in the following chemical formula 4, the following chemical formula 4 is contained in the organic film. If any of the structures represented by Structural Formulas 1 to 9 is included, such energy transfer remarkably occurs.

[0075]

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The above-listed polymers containing functional groups contained in the substances constituting the antireflection film are easily excited by ultraviolet light, and energy transfer and electron transfer easily occur.

[0077]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the effects of the present invention will be described more specifically by showing various examples and comparative examples of the present invention.

Example 1 As shown in FIG. 3A, an Al film 12 used as a wiring material was formed on a silicon substrate 11 by sputtering 400
It was deposited to a film thickness of 0 angstrom. Next, 1 g of dibutyldithiocarbamate nickel (II) was added to the solution material of the antireflection film in which 5 g of polymethylmethacrylate was dissolved in 94 g of isobutyl ketone.

In this case, since the additive dibutyldithiocarbamate nickel (II) itself has absorption in the vicinity of 250 nm, it has an antireflection effect and suppresses photodegradation of the polymer based on the above-mentioned quenching action and light absorption action. Have an effect. The solution of the antireflection film thus prepared was applied on the Al film 12 by the spin coating method, and then baked at 180 ° C. for 10 minutes to evaporate the solvent. At this time, the thickness of the antireflection film is 1000
Angstrom.

As a result of measuring the light reflectance at a wavelength of 248 nm in this state, the reflectance when the antireflection film was not formed was about 90%, but it was reduced to about 5%. It was found that a film having a good antireflection effect could be formed.

Next, the antireflection film 1 thus formed
Chemically amplified positive resist film 14 is formed on 3 and 98 ° C.
After baking for 120 seconds, it was exposed with a KrF excimer stepper (exposure amount 60 mJ / cm ² ). After that, baking is performed at 98 ° C. for 120 seconds and 0.2
Development was carried out for 120 seconds with a 1N TMAH developing solution to form a 0.25 μm line-and-space pattern. The result of observing the shape of the resist after development with an electron microscope is as shown in FIG. 3A, which shows no tailing or biting at the interface with the antireflection film 13.
A resist pattern 14 having a vertical sectional shape could be obtained.

Example 2 As shown in FIG. 3 (a), an Al thin film 12 used as a wiring material was formed on a silicon substrate 11 by sputtering.
It was deposited to a thickness of 00 Å. Next, 5 g of 2,6-di-t-butyl-4-methylphenol as a radical scavenger was added to the solution material of the antireflection film in which 5 g of polybutene sulfone and 1 g of coumarin were dissolved in 89 g of cyclohexanone.

The solution of the antireflection film thus prepared was applied on the Al thin film 12 by the spin coating method, and then baked at 180 ° C. for 10 minutes to evaporate the solvent. At this time, the thickness of the antireflection film 13 is 100
It is 0 angstrom. In this state, 248n
As a result of measuring the light reflectance at the wavelength of m, the antireflection film 13
The reflectance when not formed was about 90%, but it was reduced to about 5%, and a film having a good antireflection effect could be formed.

Next, the antireflection film 1 thus formed
Form a chemically amplified positive resist film on 3 and
After baking for 20 seconds, exposure was performed with a KrF excimer stepper (exposure amount 60 mJ / cm ² ). After that, baking is performed at 98 ° C. for 120 seconds to 0.21.
Develop with the specified TMAH developer for 120 seconds,
A 0.25 μm line and space pattern was formed.

As a result of observing the shape of the resist after development with an electron microscope, it is as shown in FIG. 3 (a), and it is vertical with no tailing or biting at the interface with the antireflection film 13. A resist pattern 14 having a cross sectional shape could be obtained.

Example 3 As shown in FIG. 3A, an Al thin film 12 used as a wiring material was formed on a silicon substrate 11 by sputtering.
It was deposited to a thickness of 00 angstroms. Next, 5 g of polysulfone was added to a solution material of the antireflection film in which 4 g of polyamide and 1 g of a coumarin derivative were dissolved in 5 g of a cyclohexanone solution in order to neutralize a basic decomposition product generated from the polyamide upon irradiation with ultraviolet rays.

The antireflection film solution thus prepared was applied on the Al thin film 12 by the spin coating method, and then baked at 180 ° C. for 10 minutes to evaporate the solvent. At this time, the thickness of the antireflection film is 1000 angstrom. In addition, as a result of measuring the light reflectance at a wavelength of 248 nm in this state, the reflectance was about 90% when the antireflection film was not formed, but it was reduced to about 5%, which is good. It was possible to form a film having a good antireflection effect.

Next, the antireflection film 1 thus formed
3, a chemically amplified positive resist film 14 is formed on the
After baking at 120 ° C. for 120 seconds, exposure was performed with a KrF excimer stepper (exposure amount 60 mJ / cm ² ).
After that, baking is performed at 98 ° C. for 120 seconds, and then 0.
Development was carried out for 120 seconds with a 21N TMAH developing solution to form a 0.25 μm line-and-space pattern.

The result of observing the shape of the resist after development with an electron microscope is as shown in FIG. 3 (a), which shows a vertical surface without tailing or biting at the interface with the antireflection film 13. A resist pattern 14 having a cross sectional shape could be obtained. By performing RIE using O ₂ gas using this resist pattern 14 as a mask, the structure shown in FIG.
As shown in (b), a pattern having a cross-sectional shape perpendicular to the cross section of the antireflection film 13 could be transferred to the antireflection film 13.

Next, as a result of etching the Al film, as shown in FIG. 3C, the wiring pattern 12 having a good sectional shape could be processed.

Comparative Example 1 The same procedure as in Example 3 was carried out except that polysulfone was not added as a neutralizing agent. Polyamide 4
g, coumarin derivative 1 g, cyclohexanone solution 95 g
To prepare a coating type antireflection film material. Using the antireflection film-forming solution thus prepared, Example 3
A 0.25 μm line-and-space pattern was formed in the same manner as in.

After the antireflection film 13 was baked, the light reflectance from the antireflection film 13 was measured. As a result, it was found that the reflectance was about 5% and the reflection was sufficiently suppressed. However, the resist pattern 1 after development
As a result of observing the shape of No. 4 with an electron microscope, it was found that the trailing was remarkable as shown in FIG.

Next, when the antireflection film 13 is etched using the resist pattern 14 as a mask, the result is as shown in FIG. 4B, and the pattern is transferred to the antireflection film 13 in a desired dimension. I couldn't.

Example 4 As shown in FIG. 5A, a BPSG film 15 used as an interlayer insulating film was deposited on a silicon substrate 11 to a thickness of 2000 angstrom. Next, polyacrate 5g
Was dissolved in 90 g of cyclohexanone, and 5 g of 2,6-di-t-butyl-4-methylphenol was added as a radical scavenger.

The solution material thus prepared was applied onto the BPSG film 15 by the spin coating method, and then 1
The solvent was vaporized by baking at 80 ° C. for 1 minute. The thickness of the organic film 16 at this time was 50 nm.

On the organic film 16 thus formed, 1 μm
After forming the chemically amplified positive resist 14 with a film thickness of m,
After baking at 120 ° C. for 90 seconds, drawing was performed using an electron beam drawing device. (Exposure amount 10
μC / cm ² ) Then, after baking at 120 ° C. for 90 seconds, development processing was performed for 90 seconds using a TMAH aqueous solution to form a 0.12 μm line-and-space pattern.

The result of observing the shape of the resist 14 after development with an electron microscope is as shown in FIG. 5 (a), which shows a vertical surface without tailing or biting at the interface with the organic film 16. A resist pattern 14 having a cross sectional shape could be obtained.

Comparative Example 2 As shown in FIG. 5B, a chemically amplified resist film 14 was formed directly on the BPSG film 15, and a line-and-space of 0.12 μm was formed in the same manner as in the above-mentioned embodiment. Resist pattern 14 was formed. Further, as shown in FIG. 5C, the organic film 17 in which the radical scavenger was not added
By using the same method as in the above-described embodiment.
2μm line and space resist pattern 14
Was formed.

As a result of observing the shape of the resist pattern with an electron microscope, it was found that the shapes were as shown in FIGS. 5 (b) and 5 (c), respectively, and had a hem. Example 5 An SOG film used as an interlayer insulating film is formed on a silicon substrate,
It was deposited to a thickness of 300 nm by the spin coating method. Next, 10 g of polysulfone was added to cyclohexanone 8
To the antireflection film solution dissolved in 8 g, 2 g of p-isopropylbenzophenone was added.

The thus prepared antireflection film-forming solution was applied onto the SOG film by spin coating, and then baked at 180 ° C. for 3 minutes to evaporate the solvent. The thickness of the organic film at this time was 90 nm. In addition, as a result of measuring the light reflectance at a wavelength of 193 nm in this state, the reflectance without the antireflection film is about 60%.
However, it was reduced to about 2%, and a film having a good antireflection effect could be formed.

Then, a chemically amplified positive resist film is formed on the antireflection film thus formed, and the chemically amplified positive resist film is formed at 120 ° C. for 1 hour.
After baking for 20 seconds, exposure was performed with an ArF excimer stepper (exposure amount 120 mJ / cm ² ). After that, baking is performed for 120 seconds at 120 ° C.
A development process was performed for 120 seconds with a 3N TMAH developing solution to form a 0.12 μm line-and-space resist pattern.

The result of observing the shape of the resist pattern after development with an electron microscope shows that a resist pattern having a vertical cross-sectional shape without tailing or biting at the interface with the antireflection film can be obtained. did it.

Although the first aspect of the present invention has been specifically described with reference to Examples 1 to 5, the present invention is not limited to these examples and various modifications can be made. .
For example, in the above examples, polymethylmethacrylate, polybutene sulfone, polysulfone, and polyacrylate were used as the resin, but the resin is not limited to this.

In the above embodiment, the exposure light is K
Although rF excimer light was used, it is not limited to this and can be used in lithography using various exposure wavelengths.

The first aspect of the present invention is that the organic film formed between the resist and the object to be processed is decomposed by irradiation with high energy during exposure, or the resist is removed from the organic film excited to an excited state. This is a general-purpose solution when energy is transferred to the constituent substances and the shape of the resist profile is deteriorated. Therefore, the organic film is not limited to a film having an action as an antireflection film,
Nitride film or BP that easily disperses acid in chemically amplified resist
A film such as an SG film or a TEOS oxide film that prevents the breakdown of an acid from a work piece having a rough film quality, an anti-scattering film that prevents the scattering of electrons from the work piece during electron beam drawing, and a conductive film that prevents charge-up. Etc. can also be used.

Example 6 This example is an example in which an organic film in which an acid decomposition product is generated by exposure is formed between a positive type chemically amplified resist and an object to be processed. As a positive type chemically amplified resist, 20 g of a suppressor resin in which 30% of phenol groups of polyhydrostyrene having a molecular weight of 12,000 were replaced with tert-riboxycarbonylmethyl groups, 1 g of onium salts, and 0.1 g of coumarin were added to 78 g of ethyl lactate. What was melt | dissolved was used.

The inhibitor resin obtained by substituting a part of the phenol group of polyhydroxystyrene with a tertiarybutoxycarbonylmethyl group is difficult to dissolve in an alkaline solvent, but is exposed to ultraviolet light to produce an onium which is an acid generator. An acid is generated from the salt, and as shown in the following reaction formula, the elimination reaction of the tertiary butyl group proceeds due to the acid-catalyzed reaction to generate a carboxyl group.

[0108]

Embedded image

As a result, the solubility in the alkaline solvent is improved, and the resist can be patterned by selectively performing the exposure. Also, by adding a dye that absorbs the exposure light, the absorption coefficient in the resist film increases and the multiple reflections that occur in the resist film are suppressed, so the dimensional controllability of the resist pattern can be improved. Is.

In this example, the following experiment was conducted in order to select, from the polymers having a sulfone group, a polymer which produces an acidic decomposition product capable of advancing an acid-catalyzed reaction by light irradiation. It was

First, 10 g of the same inhibitor resin as that used as the component of the above resist in which 30% of the phenol group of polyhydroxystyrene having a molecular weight of 12000 was substituted with a tert-riboxycarbonylmethyl group, and 5 g of polysulfone were dissolved in a cyclohexanone solution. It dissolved in 85 g.
Similarly, polyether sulfone, bisbenzyl sulfone, (2-methylbenzyl) -phenyl sulfone,
5 g of each of bis (naphthomethyl) sulfone, bis (3,4-dichlorobenzyl) sulfone and bis (4-fluorobenzyl) sulfone were dissolved in 85 g of a tetrahydrofurene solution together with 10 g of the inhibitor resin. Also,
Detergent resin 10g only tetrahydrofurene solution 90g
A sample dissolved in was also prepared.

Next, each sample solution was applied on a silicon wafer substrate to a thickness of 1 μm, and the solution was applied at 98 ° C. for 12 hours.
Baking was performed for 0 seconds, each wafer was irradiated with KrF excimer laser light at 100 mJ / cm ² , and further baked at 98 ° C. for 120 seconds.
Then, the absorption spectrum of the film formed on the wafer substrate in the infrared wavelength region was measured.

FIG. 6 shows absorption spectra of the case where the solution containing only the inhibitor resin was applied (a) and the case where the mixed solution of the inhibitor resin and bisbenzyl sulfone was applied (b). From FIG. 6, it can be seen that the absorption due to the C-H bending vibration at 1370 cm ⁻¹ is reduced when bisbenzyl sulfone is added. However, this is because the bisbenzyl sulfone is decomposed by irradiation of exposure light and sulfonic acid is generated, whereby the acid-catalyzed reaction proceeds and elimination of the tertiary butyl group proceeds.

The efficiency of conversion of the tert-riboxycarbonylcarbonyl group to the carboxyl group by the acid-catalyzed reaction, estimated from the absorption intensity by the C-H bending vibration at 1370 cm ^-1 , was evaluated by the sulfone group dissolved in the cyclohexanone solution together with the inhibitor resin. Table 1 below shows a summary of various polymers having

[0115]

[Table 1]

From Table 1 above, it is understood that bisbenzyl sulfone is the most efficient polymer among the studied polymers and can promote the acid-catalyzed reaction.

Example 7 In this example, bisbenzyl sulfone selected by the method described in Example 6 is used as an antireflection film. BP used as an insulating film material on a silicon substrate
The SG film was deposited to a thickness of 4000 angstrom.
Next, 5 g of bisbenzyl sulfone was dissolved in 95 g of isobutyl ketone to prepare a solution material for the coating type antireflection film. The prepared antireflection film solution was applied on a wafer substrate by spin coating, and then baked at 180 ° C. for 10 minutes to evaporate the solvent. The thickness of the antireflection film at this time is 510 angstroms. In addition, using the complex refractive index at the exposure wavelength in Table 2 below,
The swing ratio indicating the magnitude of the standing wave generated in the resist film with respect to the film thickness of the antireflection film is calculated as shown in FIG. From the calculation result of FIG. 7, the film thickness of the antireflection film was set to be as thin as possible and to reduce the swing ratio.

[0118]

[Table 2]

Then, the chemically amplified positive resist film prepared in Example 6 is formed on the antireflection film, and the chemically amplified positive resist film is formed at 120 ° C. at 120 ° C.
Baking was performed for 2 seconds, and exposure was performed with a KrF excimer stepper (exposure amount 34 mJ / cm ² ). The thickness of the resist after baking is 5000 angstroms.
Further, baking is performed at 98 ° C. for 120 seconds,
Development was performed for 120 seconds with a 21 N TMAH developing solution to form a contact hole pattern having a diameter of 0.15 μm.

FIG. 8B shows the sectional shape of the hole pattern obtained with the optimum exposure amount and focus value. Further, FIG. 8A shows the result of calculating the resist profile from the optical image formed in the resist film by the method described in the document mentioned in the prior art. From the calculation, it was found that the resist pattern has a taper angle because the extinction coefficient of the resist is high and the light intensity becomes weaker toward the interface with the antireflection film. However, the actually obtained resist pattern did not have a tapered shape reflecting an optical image in the film thickness direction of the resist.

Next, when the dimension of the diameter of the hole with respect to the film thickness of the resist was measured by the cross-section SEM, the dimensional fluctuation due to the standing wave generated in the resist film could not be observed within the range of the measurement accuracy. A resist pattern having good dimensional controllability could be obtained.

Further, using a magnetron RIE apparatus, the antireflection film was etched using the resist pattern as a mask. The etching conditions are excitation power of 500 W,
The degree of vacuum was 1.8 mTorr, and the flow rates of the gases used were CF ₄ = 20 SCCM, O ₂ = 8 SCCM, Ar = 1, respectively.
It is 60 SCCM.

After the etching was completed, the RIE shape of the antireflection film was observed by a cross-section SEM. As a result, the processed shape was as shown in FIG. 9A, and no dimensional conversion difference was observed.

Comparative Example 3 This comparative example shows the case where an antireflection film containing polysulfone as a component which does not decompose the inhibitor resin when exposed to exposure light is used. The film thickness of the antireflection film was set to 600 angstroms in order to make the substrate reflectance at the interface between the resist and the antireflection film the same as in Example 7. By the same method as in Example 7, a chemically amplified resist was applied on the antireflection film to form a contact hole pattern.

FIG. 8C shows the sectional shape of the hole pattern with the optimum exposure amount and focus value. From FIG. 8C, it can be seen that the taper angle is provided and the vertical sidewall shape cannot be obtained as in the seventh embodiment. FIG. 8 (c)
The relationship between the taper angle 28 defined in 1. and the conversion efficiency of the tertiarybutoxycarbonylmethyl group to the carboxyl group when various polymers having a sulfone group studied in Example 6 are added is summarized in the above Table 1. become that way.

From Table 1, it is understood that the taper angle is smaller when the polymer having high conversion efficiency is used as the antireflection film. Therefore, from this comparative example, the acid generated from the antireflection film at the time of exposure compensates the shortage of the acid-catalyzed reaction due to the shortage of the exposure amount near the interface between the resist and the antireflection film, and obtains a good resist profile. It turned out to be possible.

Comparative Example 4 A case will be described in which a dye is not added to the resist and the same antireflection film containing polysulfone as the component in Comparative Example 3 is used. The complex refractive index of the resist with respect to the exposure wavelength measured by spectral ellipsometry is n = 1.70, k = 0.02.
Then, the value of the complex refractive index of the antireflection film is the same as that of polyvinyl sulfone, and the result of the calculation of the swing ratio, which represents the magnitude of the standing wave generated in the resist film, is shown when the dye is added to the resist. And shown in comparison with FIG. From the figure, it was found that the film thickness of the antireflection film was required to be 1800 angstroms in order to obtain the same antireflection effect as in Example 2.
A chemically amplified resist was applied on the antireflection film in the same manner as in the example to form a contact hole pattern. FIG. 10B shows the cross-sectional shape of the hole pattern with the optimum exposure amount and focus value. Further, the result of calculating the resist profile from the optical image in the resist film is shown in FIG.
(A). It can be seen from FIG. 10 that due to the high transmittance of the resist, there was little change in the light intensity in the resist film, and a good resist pattern could be obtained. However, when the antireflection film is etched by the same method as that of the embodiment, a dimensional conversion difference may occur remarkably because the antireflection film is thick in the processed shape as shown in FIG. 9B. Do you get it. From this comparative example, the acidic decomposed product generated from the organic film at the time of exposure promoted the acid-catalyzed reaction in the resist film, and thus it became possible to use a resist having high absorptivity for exposure light. As a result, the magnitude of the standing wave generated in the resist film can be suppressed by the film thickness of the thin antireflection film, and the dimensional conversion difference generated during etching of the antireflection film can be reduced.

Example 8 In this example, a part of the exposure energy is transferred from the organic film formed directly under the resist to the acid generator contained in the resist, or the molecules in the organic film are transferred to the resist. The present invention relates to a resist patterning method in which electrons are transferred to an acid generator contained therein to cause a photosensitive reaction in a resist film to proceed. In this example, an experiment conducted for selecting a combination of an organic film material and an acid generator will be described.

As an acid generator, onium salt, sulfonimide, 2,2-bis (4-methoxyphenyl) -1,
1,1-trichloroethane, polysulfone as organic film material, bisether sulfone, bisbenzyl sulfone, (2-methylbenzyl) -phenyl sulfone,
Choose bis (naphthomethyl) sulfone, bis (3,4-dichlorobenzyl) sulfone, bis (4-fluorobenzyl) sulfone, polyamide, polyimide, polyisobutylene, poly-α-methylstyrene, polymethacrylic acid, polymethylmethacrylate, phenodiazine. Of these, a combination of an acid generator capable of causing energy transfer or electron transfer and an organic film material was selected.

Of the above materials, for all combinations of acid generators and organic film materials, 1 g of acid generator, 5 g of organic film material, and part of the phenol group used in Example 6 were tertiary butoxycarbonylmethyl groups. 10 g of the suppressor resin substituted with
To prepare a sample solution. A sample solution was prepared by dissolving 1 g of the acid generator and 10 g of the inhibitor resin in 89 g of a tetrahydrofuran solution without adding the organic film material.

Next, each sample solution was applied on a silicon wafer substrate to a thickness of 1 μm, and the solution was applied at 98 ° C. for 12 hours.
Baking for 0 seconds, irradiating each wafer with KrF excimer laser light, and further 1 hour at 98 ° C.
Baking was performed for 20 seconds. Considering that the added organic film material absorbs the light, the exposure amount when the KrF excimer laser light is irradiated is 20 mj / cm ² when the acid generator is used.
The exposure amount was calculated from the absorption coefficients of the acid generator and the organic film material so that the irradiation was performed with the exposure amount of.

Then, similarly to the method described in the sixth embodiment,
The absorption spectrum in the infrared wavelength region of the film formed on each wafer substrate was measured, and the conversion efficiency, which is the ratio of conversion of tertiarybutoxycarbonylmethyl group to carboxyl group by acid-catalyzed reaction, was determined.

As a result, it was found that depending on the combination of the acid generator and the organic film material, the catalytic reaction proceeded faster than when the organic film material was not added.
Regarding the combination of the acid generator and the organic film material whose acid-catalyzed reaction was increased by adding the organic film material, the ratio of conversion of tertiarybutoxycarbonylmethyl group to carboxyl group was not used when the organic film material was added. The results summarized for the cases are shown in Table 3 below.

[0134]

[Table 3]

From Table 3 above, it is understood that when the acid generator is sulfonimide and the organic film material is bis (naphthomethyl) sulfone, the sensitizing action of the acid catalyst reaction is remarkable.

The emission from the sulfonimide solid when the sulfonimide solid was excited by the KrF excimer laser light and the absorption spectrum of bis (naphthomethyl) sulfone were measured with a spectroscope.
FIG. 11 (c) shows the emission spectrum of the mixture of bis (naphthomethyl) sulfone and sulfonimide excited by KrF excimer laser light in (b).

From FIG. 11, it can be seen that the emission spectrum of bis (naphthomethyl) sulfone and the absorption spectrum of sulfonimide overlap, and the acid generator absorbs the luminescence generated from the organic film during exposure. Similarly, when the acid generator was a sulfonimide, a spectroscopic measurement was carried out on a polymer showing a sensitizing action of an acid-catalyzed reaction. As a result, sulfonimide absorbs the emission spectrum generated when the organic film material is excited by exposure light, and part of the exposure energy is transferred from bis (naphthomethyl sulfone) excited by exposure light to sulfonimide. I found out that

The organic film material is polyether sulfone, bisbenzyl sulfone, (2-methylbenzyl).
-In the case of phenyl sulfone, from the experimental results in Example 6, the polymer decomposes at the time of exposure to generate an acidic decomposed product, so that an increase in conversion efficiency due to the progress of the acid catalyst reaction is also included. However, it can be considered that the conversion efficiency of the polymer having other sulfone groups increased due to energy transfer.

On the other hand, when the acid generator is 2,2-bis (4-methoxyphenyl) -1,1,1-trichloroethane and the organic film material is phenodiazine, the sensitizing action is also observed. Assuming that the acid generator is RX and the organic film material is SH, the organic film material is excited to an excited state by the exposure light as shown by the following formula (formula (a)), and the acid is excited from the excited molecule. Electrons are transferred to the generator to generate cations and anions (equation (b)), and halide ions are generated from the anions of the acid generator to generate a halogenated acid together with the protons released from the organic film. (Equation (c))).

SH → SH ^* (a) SH ^* + RX → SH ^{+ ·} + RX ^{− ·} (b) RX ^{− ·} → R ^· + X ⁻ (c) SH ⁺ → S ^· + H ⁺ Example 9 A case where bis (naphthomethyl) sulfone selected by the method described in Example 8 is used as an antireflection film material and sulfonimide is used as an acid generator is shown.

First, a BPSG film used as an insulating film material was deposited on a silicon substrate to a film thickness of 4000 angstrom. Then, 5 g of bis (naphthomethyl) sulfone was dissolved in 95 g of isobutyl ketone to prepare a solution material for the coating type antireflection film. Next, the molecular weight is 12000
Inhibitor resin in which 30% of the phenol groups of polyhydrostyrene of (3) was replaced with tertiarybutoxycarboxylmethyl group, 1 g of sulfonimide, 0.5 g of curcumin
Was dissolved in 78.5 g of ethyl lactate to prepare a solution for forming a positive chemically amplified resist.

The prepared solution for forming an antireflection film was applied on a wafer substrate by spin coating, and then 18
The solvent was vaporized by baking at 0 ° C. for 10 minutes. The thickness of the antireflection film at this time is 510 angstroms. The method of determining the film thickness is the same as the method described in the seventh embodiment.

Then, the prepared resist solution material is applied onto the antireflection film by spin coating, and the temperature is set to 98 ° C.
The substrate was baked for 120 seconds and exposed with a KrF excimer stepper (exposure amount 34 mj / cm ² ). The film thickness of the resist after baking is 5000 angstrom. Further, baking was performed at 98 ° C. for 120 seconds, and development processing was performed for 120 seconds with a 0.21N TMAH developing solution to form a contact hole pattern having a diameter of 0.15 μm. FIG. 12B shows the cross-sectional shape of the hole pattern with the optimum exposure amount and focus value. Also,
The result of calculating the resist shape from the optical image formed in the resist film is shown in FIG.

According to the calculation, since the extinction coefficient of the resist is high, the light intensity becomes weaker toward the interface with the antireflection film, and the resist pattern has a taper angle. However, the side wall of the obtained resist pattern was vertical, and was not a tapered shape reflecting the optical image in the film thickness direction of the resist.

Next, when the dimension of the diameter of the hole with respect to the film thickness of the resist was measured by the cross-section SEM, the dimensional fluctuation due to the standing wave generated in the resist film could not be observed within the range of the measurement accuracy. A resist pattern having good dimensional controllability could be obtained. Further, when the antireflection film was etched using the magnetron RIE apparatus as in Example 8, no dimensional conversion difference was observed after the etching of the antireflection film was completed.

Comparative Example 5 An antireflection film containing polyamide, which did not show the effect of sensitizing the acid-catalyzed reaction in Example 8, was formed on the BPSG film. The film thickness of the antireflection film was set to 600 angstroms in order to make the light intensity reflectance at the interface between the resist and the antireflection film equal to that in the case of Example 9. A chemically amplified resist was applied on the antireflection film in the same manner as in Example 9 to form a contact hole pattern. FIG. 12C shows the sectional shape of the hole pattern with the optimum exposure amount and focus value.

From FIG. 12C, the resist pattern has a taper angle, and it was not possible to obtain a resist shape having vertical sidewalls as in the embodiment. When the acid generator is sulfonimide in Example 8, the sensitivity increase of the conversion efficiency from the tertiary carbonyl group to the carboxyl group improved by adding various organic film materials, Δ = (organic film material X Conversion efficiency when added) /
(Conversion efficiency in the case where the organic film material X is not added) is defined and the relation between Δ and the taper angle in various organic film materials X is summarized. As a result, it is better to use a polymer having high sensitivity as the antireflection film. It was found that the taper angle is small and the resist shape has a vertical side wall. Therefore, from this comparative example, a part of the exposure energy is transferred from the molecules in the antireflection film to the acid generator during exposure, and the acid generated from the acid generator causes the exposure amount near the interface between the resist and the antireflection film. It can be seen that the lack of acid catalyzed reaction due to the lack of is compensated.

Example 10 This example relates to a two-layer resist method in which a resist containing silicon atoms is used as an upper layer and exposure is performed with ArF excimer laser light. As a silicon-containing resist, as shown in the following reaction formula, polyhydroxystyrene having a molecular weight of 13000 in which 25% of phenol groups were replaced with trimethylsilyl groups, and triphenylsulfonium triflate as an acid generator were added to ethyl lactate as a solvent. The mixture was used. As shown in the following reaction formula, the trimethylsilyl group is eliminated by the proton generated from the acid generator to generate a phenol group, which is dissolved in an alkaline solvent and a pattern can be formed.

[0149]

[Chemical 6]

Then, in the same manner as in Example 6 or Example 8, the acid-catalyzed reaction is allowed to proceed from the molecule existing in the film under the resist to the molecule existing in the resist at the time of light irradiation. The organic materials that have action were investigated. From this, it was found that by sensitizing the acid-catalyzed reaction by using a film containing polyisobutylene as the lower layer in the two-layer resist method and using triphenylsulfonium triflate as the acid generator. It was

Also, in the same manner as in Example 8, the emission when polyisobutylene was excited at λ = 193 nm and the absorption spectrum of triphenylsulfonium triflate were prepared by mixing polyisobutylene and triphenylsulfonium triflate. The absorption spectrum of the solid was measured. From the data of these spectra, it was found that triphenylsulfonium triflate absorbs the luminescence generated from triisobutylene during exposure.

Next, an Al film used as a wiring material was deposited on the silicon substrate by a sputtering method to a film thickness of 4000 angstrom. And polyisobutylene 5.
A solution prepared by dissolving 0% by weight in cyclohexanone was applied on a wafer substrate by spin coating to form a film, and baking was performed at 180 ° C. for 120 seconds to vaporize the solvent. At this time, the film thickness of the lower layer is 50
00 angstroms. A silicon-containing resist having the above-described composition was applied on the lower layer and baked at 98 ° C. for 120 seconds to evaporate the solvent. The film thickness of the resist at this time is 800 angstrom.

Next, exposure was carried out using an ArF excimer stepper (exposure amount 120 mj / cm ² ), and baking was carried out at 98 ° C. for 120 seconds. Furthermore, TM of 0.21 regulation
Develop with AH developer for 120 seconds, then add 0.15μ
m and a line and space pattern were formed. FIG. 13B shows the cross-sectional shape of the hole pattern with the optimum exposure amount and focus value. 13A shows the result of calculating the resist shape from the optical image formed in the resist film.
Shown in

Since the resist used in this example uses polyhydroxystyrene as a resin, it has a low transmittance with respect to the exposure wavelength, and the transmittance at a film thickness of 800 Å is about 20%. Therefore, it was found from the calculation result that there is a possibility that the light intensity becomes weaker toward the interface with the antireflection film and the pattern may not be resolved. However, it was possible to resolve a resist pattern having a vertical sidewall shape, and the shape did not reflect the optical image in the film thickness direction of the resist.

Next, the lower layer was etched using a magnetron RIE apparatus. The etching conditions were such that the excitation power was 500 W, the degree of vacuum was 1.8 mTorr, and oxygen as an etchant gas was introduced at a flow rate of 12 SCCM to perform etching. As a result, the lower layer was able to be etched without running out of the resist during the etching of the lower layer.

Comparative Example 6 In this comparative example, the case where an organic material having no action of sensitizing the acid-catalyzed reaction in the resist is used as the lower layer will be described. First, 10 g of novolac resin is mixed with 9 g of ethyl lactate.
Apply the solution dissolved in 0g on the Al film,
Baking was performed for 80 seconds. At this time, the film thickness of the lower layer is 5000 angstrom.

Next, the same film thickness as in Example 10 is 800.
A silicon-containing resist was coated on the underlying layer to make it angstrom. Then, patterning was performed by the same method as in Example 10. The cross-sectional shape of the obtained resist pattern is shown in FIG. As expected from the calculation, the pattern could not be resolved due to the large absorption of the resist with respect to the exposure wavelength.

If the resist film thickness is reduced to about half, the resist pattern can be resolved, but since the resist is not broken during the etching of the lower layer, 8
It was not possible to reduce the film thickness to less than 00 angstrom. This comparative example shows that a good resist profile can be obtained in the two-layer resist method by selecting the material that causes energy transfer to the acid generator as the lower layer.

Example 11 This example relates to the case in which an acid is generated from the lower layer at the time of exposure to promote the acid-catalyzed reaction in the resist film in Example 10 and Comparative Example 6. Novolak resin 10.0 g, acid generator triphenylsulfonium triflate 1.0 g ethyl acetate lactate 89
The solution material of the lower layer was prepared by dissolving in g. As shown in Comparative Example 6, the novolac resin does not show the effect of sensitizing the acid-catalyzed reaction with triphenylsulfonium triflate.

The solution material of the lower layer thus prepared was applied onto the wafer substrate having the Al film formed thereon, and 180
Baking was performed at 300C for 300 seconds. Next, the following experiment was conducted in order to confirm whether or not acid was generated from the acid generator upon exposure with ArF excimer laser light.

That is, as shown in FIG. 14, the lower resist film 3 on the silicon wafer 31 exposed by ArF light.
3 and an acid indicator (tetrabromophenol blue sodium salt = TBPB salt) applied to the quartz wafer 31.
Then, it was examined whether or not the acid was generated from the acid generator contained in the lower layer. As a result, the TBPB absorption spectrum (λ = 629
It was found from the change in the absorption band having a peak at nm) that an acid was generated by adding an acid generator to the lower layer during exposure.

Further, as shown in Example 10, a 0.15 μm line-and-space pattern was formed on the lower layer. The cross-sectional shape of the resist pattern thus obtained is shown in FIG. From FIG. 13D, it is possible to obtain a good resist pattern in which the side walls are vertical, and the acid generated from the acid generator added to the lower layer compensates for the insufficient acid catalytic reaction in the resist lower layer. I understand.

The above Examples 6 to 11 have described the method for solving the problem in the case where the photosensitivity reaction does not proceed sufficiently in the lower layer portion of the resist due to the absorption of the resist. However, the patterning may be performed by using an electron beam or X-rays. The organic film existing directly below the resist is transferred to the resist by decomposition of the organic substances, and the exposure energy is transferred. Also, a resist pattern forming method in which the resist shape is controlled by changing the solubility of the resist by electron transfer is also within the scope of the present invention. Therefore, it is obvious that a resist other than the chemically amplified resist such as a resist using diazonaphthoquinone as a photosensitizer and a novolac resin as a resin can be applied to the present invention.

[0164]

As described above in detail, the first aspect of the present invention
According to the method of the aspect (1), since it is possible to prevent deterioration of the organic film formed between the resist used in the lithography method and the object to be processed due to light irradiation,
It is possible to prevent mixing of the organic film and the resist, prevent abnormalities in the resist profile, and form a good resist pattern.

Further, according to the method of the second aspect of the present invention, a product formed by decomposing the organic film from the organic film to the resist even if the photosensitive reaction near the interface of the resist does not proceed sufficiently. Of the photosensitivity, the transfer of exposure energy and the transfer of electrons can compensate for the shortage of the photosensitive reaction. As a result, a good resist profile and a wide process margin can be obtained.

[Brief description of drawings]

FIG. 1 is an energy-level diagram illustrating the ease with which an electron donating property occurs.

FIG. 2 is an energy level diagram for explaining the likelihood of electron donating.

FIG. 3 is a cross-sectional view showing the cross-sectional shape of the patterns obtained in Examples 1 to 3.

FIG. 4 is a sectional view showing a sectional shape of a pattern obtained in Comparative Example 1.

FIG. 5 is a cross-sectional view showing the cross-sectional shapes of the patterns obtained in Example 4 and Comparative Example 2.

FIG. 6 is a characteristic diagram showing infrared absorption spectra with and without the addition of bisbenzyl sulfone.

FIG. 7 is a characteristic diagram showing a relationship between a swing ratio and a film thickness of an antireflection film.

FIG. 8 is a sectional view showing an optical image formed in a resist film and a sectional shape of a resist pattern in Example 7 and Comparative Example 3;

FIG. 9 is a cross-sectional view showing a shape of an antireflection film after etching.

10 is a sectional view showing an optical image formed in a resist film and a sectional shape of a resist pattern in Comparative Example 4. FIG.

FIG. 11 is a diagram showing an emission spectrum and an absorption spectrum when an acid generator and / or an organic film material is exposed to light and excited.

FIG. 12 is a sectional view showing an optical image formed in a resist film and a sectional shape of a resist pattern in Example 9 and Comparative Example 5.

13 is a cross-sectional view showing a cross-sectional shape of an optical image and a resist pattern formed in a resist film in Examples 10 and 11 and Comparative Example 6. FIG.

FIG. 14 is a view showing a method used for measuring the generation of acid from the lower layer.

FIG. 15 is a sectional view showing the shape of a resist pattern obtained by a conventional method.

FIG. 16 is a sectional view showing the shape of a resist pattern obtained by a conventional method.

[Explanation of symbols]

 2 ... Vacuum level 3 ... Electron 4 ... Lowest unoccupied orbital state 5 ... Highest occupied orbital state 6 ... Energy required for ionization 7 ... Energy obtained upon ionization 11, 34 ... Silicon wafer 12 ... Al film 13, 23, 42 ... Antireflection film 14, 24, 43 ... Resist pattern 15 ... BPSG film 16, 17 ... Organic film 28 ... Taper angle 31 ... Quartz wafer 33 ... Lower layer resist

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/027 H01L 21/30 574

Claims (8)

[Claims] 1. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. A step of developing to form a pattern of a photosensitive resin film, wherein the organic film comprises a first substance that radicals are generated by the exposure, and a second substance that acts as a radical scavenger for the radicals. A method for forming a photosensitive resin film pattern, which comprises a substance. 2. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. A step of developing to form a photosensitive resin film pattern, wherein the organic film comprises a first substance excited by the exposure and a second substance acting as a quencher for the first substance. A method for forming a photosensitive resin film pattern, which comprises the substance of 3. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. The method includes the step of developing to form a photosensitive resin film pattern, wherein the organic film is a benzophenone compound or salicylate.
And a benzotriazole compound, an acrylate compound, and a methacrylic acid compound, at least one selected from the group consisting of: a method for forming a photosensitive resin film pattern. 4. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. The organic film comprises a step of developing and forming a pattern of a photosensitive resin film, wherein the organic film contains a first substance that generates an acidic or basic decomposed product by the exposure and the acidic or basic decomposed product. A method of forming a photosensitive resin film pattern, which comprises a second substance for neutralization. 5. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. The step of developing to form a photosensitive resin film pattern, wherein the organic film is decomposed by the exposure, and the decomposed product diffuses into the photosensitive resin film, whereby A method for forming a photosensitive resin film pattern, which comprises a substance that changes the solubility of the photosensitive resin film. 6. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. The organic film comprises a step of developing to form a pattern of the photosensitive resin film, wherein the organic film has a portion of energy supplied during the exposure from molecules in the organic film to molecules in the photosensitive resin film. A method of forming a photosensitive resin film pattern, which comprises a substance that changes the solubility of the photosensitive resin film at the time of development, by moving. 7. A step of sequentially forming an organic film and a photosensitive resin film on a workpiece, a step of selectively exposing the photosensitive resin film, and a step of selectively exposing the photosensitive resin film. The method includes developing and forming a photosensitive resin film pattern, wherein the organic film is formed by transferring electrons from the molecules in the organic film to the molecules in the photosensitive resin film by the exposure. A method of forming a photosensitive resin film pattern, which comprises a substance that changes the solubility of the photosensitive resin film during development. 8. A step of forming an object to be processed on a semiconductor substrate, a step of forming a photosensitive resin film pattern on the object to be processed by the method according to claim 1, and the photosensitive resin. A method of manufacturing a semiconductor device, comprising the step of processing the object to be processed using a film pattern.