JPH07199468A - Photosensitive composition and method for forming pattern using same - Google Patents

Abstract

PURPOSE:To provide a photosensitive composition which is suitably used as a resist material, provides high sensitivity to light sources of short wavelengths and high resolution, and enables a fine resist pattern of rectangular cross section to be stably obtained. CONSTITUTION:A photosensitive composition contains a compound that is dissolved by acid and becomes soluble to alkaline solutions and a compound that produces an acid when exposed to light; the compound that is dissolved by acid and becomes soluble to alkaline solutions contains a component 2 having small molecular polarities and dissolving in an alkaline solution at slow rate and a component 4 having large molecular polarities and dissolving in an alkaline solution at high rate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photosensitive composition which can be applied to photoresists and the like.

[0002]

2. Description of the Related Art A microfabrication technique by photolithography is used for manufacturing a semiconductor device such as an LSI.
Specifically, this technique is performed according to the following process. That is, first, a photoresist film is formed on a substrate such as a silicon single crystal wafer by, for example, a spin coating method. Next, after exposing this resist film, processing such as development and rinsing is performed to form a resist pattern. Then, the exposed wafer surface is etched using the resist pattern as an etching resistant mask to open lines and windows having a minute width to form a desired pattern.

In the manufacturing process of an LSI, a processing technique capable of forming a finer pattern is required for the lithography technique as the LSI is highly integrated. In response to such a demand, attempts have been made to shorten the wavelength of the exposure light source. As a concrete measure, a lithography technique using deep UV as a light source such as a KrF excimer laser (wavelength 248 nm) and an ArF excimer laser (wavelength 193 nm) is being studied.

However, in the conventional resist material,
Since the absorption of deep UV is excessively large, a portion (eg,
UV light cannot sufficiently reach the interface region of the resist film, which is in contact with the substrate. As a result, in the exposed portion of the resist film, chemical change due to exposure does not sufficiently occur over the entire film thickness, and the solubility in the developing solution in the film thickness direction becomes uneven. In particular, the solubility in the portion away from the surface of the resist film as described above is not sufficient, and the cross-sectional shape of the resist pattern after development becomes triangular. Therefore, when the obtained resist pattern is used as an etching resistant mask, a target fine pattern cannot be transferred to a substrate or the like, which is a problem.

As a resist material that solves such a problem, a chemically amplified resist has been proposed. A chemically amplified resist is a photosensitizer containing a compound that generates a strong acid upon irradiation with light, that is, an acid generator and a compound that decomposes a hydrophobic group by the generated acid to become a hydrophilic substance. It is a composition. Specifically, H.264. It
o, C, G, Wilson, J .; M. J. French
et al., U.S. Pat. No. 4,491,628 (1985).
Discloses a positive resist containing a polymer obtained by blocking the hydroxyl group of poly (p-hydroxystyrene) with a butoxycarbonyl group, and an onium salt as an acid generator. In addition, M. J. O'Brien, J, V. Cr
ivello, SPIE Vol, 920, Advan
ces inResist Technology a
nd Processing, p42, (1988), m-cresol novolac resin and naphthalene-2-.
A positive resist containing a carboxylic acid-tert-butyl ester and a triphenylsulfonium salt as an acid generator is disclosed. Furthermore, H. Ito, SPIE Vo
1, 920, Advances in Resist
Technology and Processing,
p33, (1988), 2,2-bis (4-ter)
A positive resist containing t-butoxycarbonyloxyphenyl) propane, a polyphthalaldehyde salt, and an onium salt as an acid generator is disclosed.

[0006] In these chemically amplified resists, the acid generated from the acid generator functions as a catalyst, and even a trace amount efficiently causes a chemical change inside the resist. As a result, when the resist film is exposed, the reaction sufficiently progresses even in the inside of the film where the radiation is hard to reach as compared with the film surface, and the cross-sectional shape of the resist pattern formed is being improved. However, in the above resist, if the content of the dissolution inhibiting group is increased in order to enhance the resolution, the compatibility with the resin or the resin having the dissolution inhibiting group deteriorates and phase separation occurs. This phase separation causes unevenness on the surface and side surfaces of the pattern after the development process, and as a result, a high resolution pattern cannot be formed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a fine resist pattern having a rectangular cross section, which has high sensitivity and high resolution particularly for a light source of short wavelength. An object is to provide a photosensitive composition that can be stably obtained.

[0008]

In order to solve the above-mentioned problems, the present invention relates to a compound which is decomposed by an acid and becomes soluble in an alkaline solution (dissolution inhibitor), and a compound which generates an acid when irradiated with light. (Acid generator), which is a photosensitive composition, wherein the compound that is decomposed by the acid to be soluble in an alkaline solution is a) a component having a small molecular polarity and a slow alkali dissolution rate, and b) Provided is a photosensitive composition containing a component having a large molecular polarity and a high alkali dissolution rate.

Further, in the present invention, in the above-mentioned photosensitive composition, the component a has 20% or more of its alkali-soluble groups protected by a dissolution inhibiting group and has a weight average molecular weight of 5,000.
The above-described polymer compound, wherein the component b is a compound in which less than 20% of its alkali-soluble groups are protected by a dissolution inhibiting group and which has a weight average molecular weight of less than 10,000. I will provide a.

Furthermore, in the present invention, in the above photosensitive composition, the component a is a compound having a substituent in which a phenol group is protected by a dissolution inhibiting group, and the component b is a carboxyl group protected by a dissolution inhibiting group. Provided is a photosensitive composition, which is a compound having a substituent.

The present invention further includes a compound which is decomposed by an acid to be soluble in an alkaline solution, an alkali-soluble polymer, a compound which generates an acid upon irradiation with light, and a compound represented by the following general formula (1): A photosensitive composition comprising a polyhydric phenol compound represented by I).

[0012]

[Chemical 1] (In the general formula (I), R ¹ and R ² each independently represent a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.) In addition, the present invention Is a compound in which a hydroxyl group in the phenol skeleton of the polyhydric phenol compound represented by the general formula (I) shown in Chemical Formula 1 is protected by a dissolution inhibiting group, a compound which generates an acid when irradiated with light, and an alkali. A photosensitive composition comprising a soluble polymer is provided.

Further, the present invention comprises a compound which is decomposed by an acid and becomes soluble in an alkaline solution, and a compound which generates an acid by irradiation of light, and is decomposed by the acid and soluble in an alkaline solution. The compound consisting of a component having a small molecule polarity and a slow alkali dissolution rate, and a step of forming a photosensitive composition on the substrate, which comprises a component having a large molecule polarity and a high alkali dissolution rate, It comprises a step of pattern-exposing the photosensitive composition into a predetermined shape, a step of baking the exposed photosensitive composition, and a step of developing the baked photosensitive composition with an alkaline solution. A method for forming a pattern is provided.

The present invention will be described in detail below.

Examples of the dissolution inhibiting group for protecting the alkali-soluble group include tert-butyl ester of carboxylic acid and tert-butyl ester as disclosed in JP-A-2-27660.
A protecting group having a tertiary carbon such as butyl carbonate, a protecting group having a secondary carbon such as cyclohexyl, sec-butyl group and isopropyl group as disclosed in JP-A-63-13943, Unstable to acids such as trialkyl group and phenylsilyl group as disclosed in JP-A-60-52845, tetrahydropyranyl group and methylmethoxy group as disclosed in JP-A-2-19847. Protecting groups may be mentioned.

As the alkali-soluble compound, a resin containing a hydroxy group-introduced aryl group or carboxy group is desirable. Specifically, phenol novolac resin, cresol novolac resin, xylenol novolac resin, vinylphenol resin, isopropenylphenol resin, vinylphenol and acrylic acid, methacrylic acid derivative, acrylonitrile, styrene derivative and other copolymers; isopropenylphenol and Copolymers of acrylic acid, methacrylic acid derivatives, acrylonitrile, styrene derivatives, etc .; Copolymers of styrene derivatives with acrylic resins, methacrylic resins, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, acrylonitrile, etc .; or these Examples of the polymer include a compound containing silicon. However, from the viewpoint of resistance to dry etching, a resin containing an aromatic ring is preferable, and examples thereof include phenol novolac resin and cresol novolac resin.

Further, a polyhydric phenol compound, a polyhydric carboxylic acid compound or the like may be used.

As the compound (acid generator) which generates an acid upon irradiation with light, which corresponds to the photosensitizer in the photosensitive composition of the present invention, various known compounds and mixtures thereof can be used. it can. For example, CF ₃ S
^{_{O 3 -, p-CH 3}} PhSO 3 -, p-NO 2 PhSO
A diazonium salt, a phosphonium salt, a sulfonium salt, an iodonium salt, an organohalogen compound, orthoquinonediazide sulfonic acid ester having _3- ^{and the} like as a counter anion can be used. Further, an organic halogen compound known as a photoinitiator that forms a free radical is also a compound that forms a hydrohalic acid, and can be used as a compound that generates an acid upon irradiation with light in the present invention.

Specific examples of the acid generator include di (paratertiarybutylphenyl) iodonium trifluoromethanesulfonate, benzointosylate, orthonitrobenzene paratoluenesulfonate, triphenylsulfonium trifluoromethanesulfonate, tri (tertiarybutylphenyl) sulfonium. Examples thereof include trifluoromethanesulfonate, benzenediazonium paratoluenesulfonate, tris-dibromomethyl-s-triazine, o-naphthoquinonediazide-4-sulfonic acid ester and the like.

The amount of the acid generator compounded in the photosensitive composition of the present invention is preferably in the range of about 0.01 to about 20% by weight, based on the total weight of the solid content of the photosensitive composition. The range is more preferably 0.1 to 10% by weight.
If the blending amount is less than 0.01% by weight, the effect of adding the compound cannot be obtained. On the other hand, if the blending amount exceeds 10% by weight, the coating property may be deteriorated during film formation.

Used in the photosensitive composition of the present invention, a)
A component having a small molecule polarity and a low alkali dissolution rate and a component b) having a large molecule polarity and a high alkali dissolution rate are mixed so that at least 1% by weight of any component is present.

In the photosensitive composition of the present invention, if necessary, for example, a surfactant as a coating film modifier, a base such as amines as an acid trap agent for suppressing acid diffusion, and the like. , A carboxylic acid as a dissolution rate adjusting agent, an alkali-soluble compound such as phenols, or a dye as an antireflection film may be added.

Next, the polarity of the molecule of the a component is small,
The component having a slow alkali dissolution rate and the component having a large polarity of the molecule of the component b and having a high alkali dissolution rate will be described in detail.

The polarity of the molecule is related to the protection rate of the alkali-soluble group in the dissolution inhibiting group, and the higher the protection rate, the smaller the polarity. Further, the dissolution rate in alkali becomes slower as the molecular weight becomes larger, and becomes faster as the molecular weight becomes smaller. For example, the polarity of the high molecular weight compound in which the alkali-soluble group is protected by the dissolution inhibiting group becomes smaller as the protection rate becomes higher, and conversely becomes larger as the protection rate becomes lower.

Further, the rate of alkali dissolution also varies depending on the alkali-soluble group to be protected, and for example, the dissolution rate of the compound in which the carboxyl group is protected by the dissolution inhibiting group is faster than that in the case of the compound in which the phenol group is protected.

These factors that give a relative difference in the polarity of the molecule and the alkali dissolution rate are arbitrarily selected to obtain a component having a small polarity and a slow alkali dissolution rate and a component having a large polarity and a high alkali dissolution rate. . These two types having contradictory properties are used to prepare the photosensitive composition of the present invention.

In the first embodiment, a compound having a weight average molecular weight of 5,000 or more and having an alkali-soluble group protected by 20 mol% or more is used as the component a, and the component b has a weight average molecular weight of Less than 10,000,
A compound having an alkali-soluble group protection rate of less than 20 mol% is used.

When the protection rate of the alkali-soluble group in the dissolution inhibiting group is lower than 20%, the dissolution rate ratio between the exposed area and the unexposed area cannot be kept, resulting in poor resolution. Therefore, the protection rate of the dissolution inhibiting group in the high molecular weight component is preferably 20% or more, and the protection rate of the low molecular weight component is 20% or more.
% Is desirable.

Examples of the compound having a weight average molecular weight of less than 10,000 include polyhydric phenol compounds and polyvalent carboxylic acid compounds among the above-mentioned alkali-soluble compounds, and compounds other than these have a weight average molecular weight of 10, 000
It is the above polymer compound.

The protection rate of the alkali-soluble group in the dissolution inhibiting group of each component can be set to a predetermined value in the manufacturing process.

In the second embodiment, a compound having a substituent in which a phenol group is protected by a dissolution inhibiting group is used as the component a, and a substituent in which a carboxyl group is protected by a dissolution inhibiting group is used as the component b. Compound is used.

As the phenol compound, a resin having a phenol group or a low molecular weight compound is used. Specifically, phenol novolac resin; cresol novolac resin; xylenol novolac resin; vinyl phenol resin; isopropenyl phenol resin; copolymer of vinyl phenol and acrylonitrile, styrene derivative, allyl acid ester, methacrylic acid ester, etc .; isopropenyl The resin may be a copolymer of phenol and acrylonitrile, a styrene derivative, an acrylic acid ester, a methacrylic acid ester, or the like. As the low molecular weight phenol compound, a substituted or unsubstituted phenol or a polyhydric phenol compound is used, and specifically,
Examples thereof include phenol, t-butylphenol, amylphenol, xylenol, isopropylphenol, bisphenol A, bisphenol S, bisphenol F, triphenol derivative, and a condensate of a triphenol derivative and a phenol compound.

As the carboxylic acid compound, a resin having a carboxyl group or a low molecular weight compound is used. Specifically, a resin made of acrylic acid or its derivative; a resin made of methacrylic acid or its derivative; acrylic acid and acrylonitrile, a styrene derivative,
Copolymers with vinyl group- or substituted vinyl group-containing monomers such as acrylic acid esters and methacrylic acid esters; of methacrylic acid and vinyl group- or substituted vinyl group-containing monomers such as acrylonitrile, styrene derivatives, acrylic acid esters, and methacrylic acid esters Copolymers; maleic acid polymers; copolymers of maleic acid with vinyl group- or substituted vinyl group-containing monomers such as styrene derivatives, methyl vinyl ether and acrylonitrile. Examples of the low molecular weight compound include phenyl group-containing compounds such as substituted or unsubstituted benzoic acid, and carboxylic acids composed of alkyl derivatives such as malic acid and hexane.

In the following third and fourth aspects, the photosensitive composition of the present invention is produced using a compound prepared by combining the factors that determine the polarity of the molecule and the alkali dissolution rate.

In the third embodiment, the polyhydric phenol compound shown in Chemical formula 1 is used as the b component having a large polarity, and the alkali-soluble polymer is used as the a component. The alkali-soluble polymer may be used as a polymer dissolution inhibitor in which the alkali-soluble group is protected by a dissolution inhibiting group.

The polyhydric phenol compound has a protection rate of the alkali-soluble group of less than 20% in the first embodiment,
It corresponds to a compound having a weight average molecular weight of less than 10,000. A triphenol compound represented by the following general formula (II) is converted to methylol with formalin in an alkaline solution, and further represented by the general formula (III). It can be easily synthesized by condensation with a phenol compound.

[0037]

[Chemical 2] Examples of the phenol compound represented by the general formula (III) include, for example, phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol. , M-propylphenol, p-propylphenol, o-iso-propylphenol, m-is
o-propylphenol, p-iso-propylphenol, o-n-butylphenol, m-n-butylphenol, p-n-butylphenol, o-iso-butylphenol, m-iso-butylphenol, p-i
so-butylphenol, ot-butylphenol,
m-t-butylphenol, pt-butylphenol, o-amylphenol, m-amylphenol, p
-Amylphenol, o-iso-amylphenol,
m-iso-amylphenol, p-iso-amylphenol, o-cyclohexylphenol, m-cyclohexylphenol, p-cyclohexylphenol,
2,3-xylenol, 2,4-xylenol, 2,5
-Xylenol, 2,6-xylenol, 2,3-di-
Isopropylphenol, 2,4-di-isopropylphenol, 2,5-di-isopropylphenol, 2,
6-di-isopropylphenol, 2,3-di-t-butylphenol, 2,4-di-t-butylphenol,
2,5-di-t-butylphenol, 2,6-di-t-
Butylphenol and the like can be mentioned.

Examples of the dissolution inhibiting group that can be used include
t-butoxycarbonyl group, tetrahydropyranyl group,
Examples thereof include t-butoxycarbonylmethyl group.

Examples of the alkali-soluble polymer include poly (p-hydroxystyrene), a copolymer of m-isopropenylphenol and acrylonitrile, and p.
-Copolymer of isopropenylphenol and methyl methacrylate, Copolymer of p-hydroxystyrene and styrene, Copolymer of p-isopropenylphenol and styrene, Copolymer of m-isopropenylphenol and styrene Examples thereof include a polymer, a copolymer of m-hydroxystyrene and styrene, and a copolymer of t-butyl methacrylate and methyl methacrylate. These polymers are
They may be used alone or in the form of a mixture.

The degree of protection of the dissolution inhibiting group in the polymer dissolution inhibiting agent is 5 to 100%, preferably 10 to 50%.
Is the range. If this protection rate is less than 5%, a sufficient alkali dissolution inhibiting effect cannot be given to the alkali-soluble polymer. Depending on the type of dissolution inhibiting group, development with an alkaline aqueous solution may become impossible at a high protection rate.

In the fourth embodiment, as a component having a small polarity, a compound obtained by protecting the hydroxyl group in the phenol skeleton of the polyhydric phenol represented by the general formula (I) shown in Chemical Formula 1 with a dissolution inhibiting group. And an alkali-soluble polymer is used as the component b to prepare a photosensitive composition.

The dissolution rate of the polyhydric phenol compound represented by the general formula (I) is slower than the dissolution rate of the alkali-soluble polymer.

As the dissolution inhibiting group that can be used here, the same dissolution inhibiting groups that protect the alkali-soluble group of the above-mentioned alkali-soluble compound can be used. The average protection rate of these dissolution inhibiting groups with respect to the polyhydric phenol compound is 5 to 100%, preferably 10 to 100%. If this introduction rate is less than 5%, a sufficient alkali dissolution inhibiting effect cannot be given to the polyhydric phenol compound.

As the alkali-soluble polymer, the same ones as described above can be used.

A polymer dissolution inhibitor in which an alkali-soluble group is protected by a dissolution-inhibiting group may be used together with these alkali-soluble polymers. Examples of dissolution inhibitors that may be used include the compounds mentioned above.

The photosensitive composition of the present invention can be particularly preferably used as a positive photoresist because of the function of the acid generator. That is, in the photosensitive composition of the present invention, the acid-unstable dissolution inhibiting group acts as a hydrophobic protecting group in the unexposed state as described above, and therefore the solubility in alkali is suppressed. On the other hand, at the time of exposure, an acid is generated from the acid generator in the exposed portion by the light irradiation, and the acid decomposes the dissolution inhibiting group that has blocked the alkali-soluble group of the alkali-soluble compound. The dissolution inhibiting group changes from a hydrophobic protecting group to a hydrophilic group such as a hydroxyl group or a carboxylic acid group. As a result, in the exposed region of the photosensitive composition, the solubility of the compound, the alkali solubility of which has been suppressed, in the alkali developer is increased. Thereafter, by subjecting the photosensitive composition to a developing treatment with an alkali developing solution having an appropriate concentration, only the exposed region of the photosensitive composition can be dissolved and removed, and a positive resist pattern is formed. To be done.

In the photosensitive composition of the present invention,
When a suitable organic developer is used in the developing step after exposure, a negative pattern can be formed because the hydrophobic unexposed area is dissolved.

Next, a more specific pattern forming process when the photosensitive composition of the present invention is used as a photoresist will be described.

First, the photosensitive composition of the present invention is dissolved in an organic solvent, the solution is applied onto a substrate by a spin coating method or a dipping method, and then dried by heating at 60 ° C. to 140 ° C. to form a resist film. To do. If the temperature is lower than 60 ° C, the resist film is insufficiently dried, whereas if the temperature exceeds 140 ° C, the performance of the resist may be deteriorated due to the modification of each component in the composition.

As the substrate, for example, a silicon wafer, a silicon wafer having a stepped surface on which various insulating films, electrodes, wirings and the like are formed, a blank mask and the like can be used. Examples of the organic solvent that dissolves the photosensitive composition include cyclohexanone, acetone, methyl ethyl ketone, ketone-based solvents such as methyl isobutyl ketone, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, and butyl cellosolve acetate. Ester solvents such as ethyl acetate, butyl acetate, and isoamyl acetate. These organic solvents can be used alone or in the form of a mixture.

Next, pattern exposure is performed on the resist film. At this time, acid is generated in the exposed portion of the resist film. The light source for the exposure here is, for example, i of a mercury lamp.
Rays, h rays, g rays, xenon lamps, ultraviolet rays such as KrF excimer laser, ArF excimer laser, X rays, electron beams, and ion beams can be used. As a specific method of pattern exposure, when ultraviolet rays or X-rays are used,
Selective exposure is performed on the resist film through a predetermined pattern mask. On the other hand, when an electron beam, an ion beam or the like is used, the resist film can be directly subjected to pattern exposure by scanning these radiations without using a mask.

Subsequently, the resist film after pattern exposure is heat-treated (baked). This treatment condition varies depending on the type of the acid generator, but can be, for example, 30 seconds to 600 seconds in the range of 40 ° C. or higher and 140 ° C. or lower.
By such baking, in the exposed portion of the resist film,
The acid diffuses and reacts with the compound having a substituent labile to the acid. In this compound, the substituent is decomposed to be an alkali-soluble compound. The baking temperature is 4
If the temperature is lower than 0 ° C, the decomposition reaction of the dissolution inhibiting group by the generated acid does not proceed sufficiently in the exposed portion of the resist film. On the other hand, when the temperature exceeds 140 ° C., thermal decomposition proceeds in the unexposed portion of the resist film, which may reduce the contrast of the resist pattern finally formed.

Next, the resist film after baking is developed using an alkaline solution to selectively dissolve and remove the exposed portion with bad resist to obtain a desired pattern. Any alkaline solution may be used as the developing solution as long as it has a property that the exposed portion of the resist film is rapidly dissolved and the dissolution rate with respect to other exposed portions is extremely low. Specific examples include a tetramethylammonium-based aqueous solution such as a tetramethylammonium hydroxide aqueous solution and an inorganic alkali aqueous solution such as potassium hydroxide and sodium hydroxide. These alkaline aqueous solutions are usually used at a concentration of 15% by weight or less. As the developing means, for example, a dipping method, a spray method or the like can be used.

The developed substrate and resist film (resist pattern) are rinsed with water or the like, and dried.

Using the resist pattern formed as described above as a mask, the substrate (wafer) is etched by a wet etching method, a dry etching method or the like. When forming a fine pattern of 3 μm or less, a dry etching method is preferable.

The wet etching agent can be appropriately selected according to the etching target. For example, when the etching target is a silicon oxide film, an aqueous solution of phosphoric acid, an aqueous solution of acetic acid, an aqueous solution of nitric acid or the like can be used. For this, an aqueous solution of cerium ammonium nitrate can be used.

As the dry etching gas, for example, CF ₄ , C ₂ F ₆ , CCl ₄ , BCl ₃ , Cl ₂ ,
For example, HCl may be used, and these gases may be used in combination as necessary.

Regarding the etching conditions, based on the combination of the type of substrate on which the fine pattern is formed and the photosensitive composition, the concentration of the wet etching agent in the reaction tank or the concentration of the dry etching gas, the reaction temperature, etc. , Reaction time and the like can be set, respectively, but the method is not particularly limited.

Further, after etching, the resist pattern of the photosensitive composition remaining on the substrate, and the flattening layer remaining when a multilayer resist technique is adopted are removed by, for example, a release agent (J-100). : Nagase Kasei Co., Ltd.), oxygen gas plasma, etc.

In addition to the above steps, other steps can be adopted as required. For example, the adhesiveness between the resist film formed by the photosensitive composition of the present invention and the substrate, and the adhesiveness between the resist film and the planarization layer, the planarization layer and the substrate when the multilayer resist technique is adopted, For the purpose of improvement, each layer is pretreated. In addition, baking may be performed before and after the development treatment, and ultraviolet ray re-irradiation may be performed before the dry etching.

[0061]

The photosensitive composition of the present invention contains a compound which is decomposed by an acid and becomes soluble in an alkaline solution, and a compound which generates an acid when irradiated with light, and the compound which is soluble in the alkaline solution is , A component having a small molecule polarity and a slow alkali dissolution rate, and a component having a large molecule polarity and a high alkali dissolution rate.

The inventors of the present invention applied a solution containing a photosensitive composition onto a substrate and dried it. In the resist film, components having small polarity were concentrated near the surface of the resist layer, and polar components were present near the substrate. It has been found that there is a distribution in which large components of are concentrated.

Further, it was found that the dissolution rate in the film thickness direction of the photosensitive composition was such that the cross-sectional shape became vertical by making the upper layer near the surface slow and the lower layer fast.

The polarity of the molecule is determined by the degree of protection of the alkali-soluble group in the dissolution inhibiting group, and the alkali dissolution rate is determined by the molecular weight. The type of alkali-soluble group to be protected is also a factor that determines the rate of alkali dissolution.

Therefore, by combining these factors, the alkali dissolution rate of the component having a small polarity existing on the surface is slowed, and the alkali dissolution rate of the component having a large polarity existing in the lower layer is increased. That is, the dissolution rate of the resist film coated with the photosensitive composition of the present invention is relatively slow in the vicinity of the surface exposed to the alkaline solution for the longest time and relatively in the vicinity of the substrate exposed to the alkaline solution for the shortest time. Get faster. Therefore, when the photosensitive composition of the present invention is used, it is possible to form a fine pattern having a rectangular cross-sectional shape.

Next, the above mechanism will be described with reference to the drawings.

FIG. 1 is a process chart showing a method for forming a pattern using the photosensitive composition of the present invention.

FIG. 1A shows a state immediately after the resist film 6 containing the component 2 having a small polarity, the component 4 having a large polarity, the photosensitizer 5, and the solvent 3 is applied on the substrate 1. As shown in FIG. 1A, the component 2 having a small polarity and the component 4 having a large polarity are randomly present in the resist film immediately after coating.

FIG. 1B shows a state in which the solvent 3 present in the resist film 6 is volatilized to dry the resist film. At this time, the component 2 having a small polarity and the component 4 having a large polarity are shown. There is a distribution between and. That is, the component 2 having a small polarity is concentrated near the surface of the resist film, while the component 4 having a large polarity is concentrated near the substrate.

Next, as shown in FIG. 1C, the resist film 6 is irradiated with exposure light 8 through a mask 7 having a desired pattern, and then heat treatment is performed. By these treatments, an acid is generated in the exposed area and the acid decomposes the dissolution inhibiting group.

Finally, the resist film is developed with an alkaline aqueous solution to dissolve the exposed portion. As described above, in the photosensitive composition of the present invention, the upper layer of the resist film has a slower dissolution rate and the lower layer has a slower dissolution rate. Therefore, the resist pattern 9 having a vertical shape can be formed with high resolution.

[0072]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Example 1) The hydroxyl group of polyparavinylphenol (weight average molecular weight: 35,000) was converted to tert-bromoacetate.
By reacting with butyl, a polymer in which 25% of the hydroxyl group was t-butylacetic acid was obtained, and was named compound A-1. Further, a polymer in which a t-butoxycarbonylmethyl group was introduced into 5 mol% of hydroxyl groups of polyparavinylphenol (weight average molecular weight: 7,000) was obtained, and compound A-
It was set to 6.

Compound A-1 and compound A-6 are a compound having a small polarity and a small dissolution rate, and a compound having a large polarity and a large dissolution rate, respectively. In this example, as dissolution inhibitors I and II, To use.

23 g of the above compound A-1 and compound A-6
2 g, acid generator triphenylsulfonium trifluoromethanesulfonate (B-2) 250 mg, and tri-n-butylamine (C-1) 100 mg as an additive were dissolved in methyl methoxypropionate (S-1) 75 g, and this solution was prepared. Was filtered through a 0.2 μm fluororesin membrane filter to prepare a solution containing the photosensitive composition of the present invention.

Next, the solution is applied onto a silicon wafer and dried on a hot plate at 100 ° C. for 1 minute,
A resist film having a thickness of 10 μm was formed. Then, KrF is applied to the resist film through a mask having a predetermined pattern.
Exposure (50 mJ / cm ² ) was performed using a reduction projection exposure machine using excimer laser light (248 nm). Further, the resist film after exposure is placed on a hot plate at 90 ° C. for 3
After baking for a minute, the resist pattern was obtained by immersing in a tetramethylammonium hydroxide Wednesday collar with a concentration of 2.38% for 1 minute, developing and further washing with water. When the cross section of this pattern was observed with a scanning electron microscope, a high-precision pattern having a rectangular cross section with a line width of 0.25 μm and a resist side surface angle of 89.5 ° was formed. (Examples 2 to 6) A resist solution was prepared according to the composition shown in Table 1 below, applied to a silicon wafer in the same manner as in Example 1 and patterned, and then the cross section of the obtained pattern was observed. As shown in the table, a high precision resist pattern having a rectangular cross section was formed.

[0076]

[Table 1] (Examples 7 to 12) Resist solutions were prepared according to the compositions shown in Table 2 below.

In these examples, dissolution inhibitor I
As the dissolution inhibitor II, a compound having a substituent in which a phenol group is protected by a dissolution inhibitor that is decomposed by an acid is used.
As the compound, a compound having a substituent in which a carboxyl group was protected by a dissolution inhibiting group was used.

Each resist solution was applied to a silicon wafer in the same manner as in Example 1 and patterned, and then the cross section of the pattern was observed. A resist pattern was formed.

The compounds used are shown in Chemical Formulas 3 to 11 below.

[0080]

[Table 2]

[0081]

[Chemical 3]

[0082]

[Chemical 4]

[0083]

[Chemical 5]

[0084]

[Chemical 6]

[0085]

[Chemical 7]

[0086]

[Chemical 8]

[0087]

[Chemical 9]

[0088]

[Chemical 10]

[0089]

[Chemical 11] (Comparative Examples 1 and 2) As the dissolution inhibitor I and the dissolution inhibitor II, a compound having a small polarity and a large dissolution rate at the time of exposure, and a compound having a large polarity and a small dissolution rate are used, respectively. The resist solution of Comparative Example 1 and the resist solution of Comparative Example 2 containing no single dissolution inhibitor were prepared according to the compositions shown in Table 3 below. When the obtained resist solution was applied and patterned in the same manner as in Example 1, only a pattern having poor resolution and side angle was obtained.

[0090]

[Table 3] (Example 13) Compound E as a polyhydric phenol compound
-1 of 0.1 g, compound D-1 as a dissolution inhibitor 8
and compound B-2 (triphenylsulfonium trifluoromethanesulfonate) as an acid generator.
2 g of methyl methoxypropionate (S-1) 23 g
Dissolved in. The resulting solution was filtered using a 0.2 μm fluororesin membrane filter to prepare a solution containing the photosensitive composition of the present invention.

Next, the solution was applied onto a silicon wafer and baked on a hot plate at 100 ° C. for 2 minutes to form a resist film having a thickness of 1.0 μm. continue,
The resist film was exposed (50 mJ / cm ² ) through a mask having a predetermined pattern using a reduction projection exposure machine using KrF excimer laser light (248 nm). Further, after the exposed resist film is baked on a hot plate at 100 ° C. for 2 minutes, it is immersed in an aqueous solution of tetramethylammonium hydroxide having a concentration of 2.38% for 1 minute for development, and then washed with water to obtain a resist pattern. It was When the cross section of this pattern was observed with a scanning electron microscope, a high-precision pattern having a line width of 0.275 μm and a resist side surface angle of 88.9 ° was formed. (Examples 14 to 18) A resist solution was prepared according to the composition shown in Table 4 below, applied to a silicon wafer and patterned in the same manner as in Example 13, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision pattern having a rectangular cross section was formed.

The compounds used are represented by the following chemical formulas 12 to 16
Shown in.

[0093]

[Table 4]

[0094]

[Chemical 12]

[0095]

[Chemical 13]

[0096]

[Chemical 14]

[0097]

[Chemical 15]

[0098]

[Chemical 16] (Examples 19 to 24) A resist solution was prepared according to the composition shown in Table 5 below, coated on a silicon wafer in the same manner as in Example 13 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision pattern having a rectangular cross section was formed.

[0099]

[Table 5] (Examples 25 to 30) A resist solution was prepared according to the composition shown in Table 6 below, coated on a silicon wafer in the same manner as in Example 13 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision pattern having a rectangular cross section was formed.

[0100]

[Table 6] (Examples 31 to 36) A resist solution was prepared according to the composition shown in Table 7 below, applied to a silicon wafer in the same manner as in Example 13 and patterned, and then the cross section of the obtained pattern was observed. As a result, a high-precision pattern having a rectangular cross section was formed as shown in the table.

[0101]

[Table 7] (Comparative Example 3) A resist solution was prepared with the same composition as in Example 13, except that the polyhydric phenol compound was not added,
After coating and patterning on a silicon wafer in the same manner as in Example 13, the cross section of the obtained pattern was observed. The sparingly soluble layer remained in the shape of an eaves on the upper part of the pattern, and the cross section having a line width of 0.325 μm became a T-shaped resist pattern. (Example 37) 10 g of compound F-1 (average introduction ratio of inhibiting group: 65%) as a dissolution inhibitor of polyhydric phenol, and 15 g of compound G-1 (poly p-vinylphenol) as an alkali-soluble polymer. , Compound B as an acid generator
1 g of -1 (2,3,4,4'-naphthoquinodiazide-4-sulfonic acid triester of tetrahydroxybenzophenone) was dissolved in 74 g of ethyl lactate (Compound S-2). The resulting solution was filtered using a 0.2 μm fluororesin membrane filter to prepare a solution containing the photosensitive composition of the present invention.

Next, the solution was applied onto a silicon wafer and baked on a hot plate at 100 ° C. for 1 minute to form a resist film having a thickness of 1.0 μm. continue,
The resist film was exposed (50 mJ / cm ² ) through a mask having a predetermined pattern using a reduction projection exposure machine using KrF excimer laser light (248 nm). Furthermore, after the exposed resist film is baked on a hot plate at 90 ° C. for 3 minutes, it is immersed in an aqueous solution of tetramethylammonium hydroxide having a concentration of 2.38% for 1 minute for development, and then washed with water to obtain a resist pattern. It was When the cross section of this pattern was observed with a scanning electron microscope, the side angle of the resist was 8 when the line width was 0.30 μm.
A high-precision pattern of 8.9 ° was formed. (Examples 38 to 42) A resist solution was prepared according to the composition shown in Table 8 below, applied on a silicon wafer in the same manner as in Example 37 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision resist pattern having a rectangular cross section was formed.

The compounds used are represented by the following chemical formulas 17 to 20.
Shown in.

[0104]

[Table 8]

[0105]

[Chemical 17]

[0106]

[Chemical 18]

[0107]

[Chemical 19]

[0108]

[Chemical 20] (Examples 43 to 48) A resist solution was prepared according to the composition shown in Table 9 below, coated on a silicon wafer in the same manner as in Example 37 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision resist pattern having a rectangular cross section was formed.

[0109]

[Table 9] (Examples 49 to 54) A resist solution was prepared according to the composition shown in Table 10 below, coated on a silicon wafer in the same manner as in Example 37 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision resist pattern having a rectangular cross section was formed.

[0110]

[Table 10] (Examples 55 to 60) A resist solution was prepared according to the composition shown in Table 11 below, coated on a silicon wafer in the same manner as in Example 37 and patterned, and then the cross section of the obtained pattern was observed. However, as shown in the table, a high precision resist pattern having a rectangular cross section was formed.

[0111]

[Table 11] (Comparative Example 3) Bisphenol A was used instead of polyhydric phenol, and a dissolution inhibitor was prepared by introducing 100% of t-butoxycarbonyl group as a dissolution inhibitor group. This dissolution inhibitor was mixed in the same ratio as in Example 37 to prepare a resist solution, and patterning was performed by the same method and conditions as in Example 37. After development, it became cloudy and holes of 10 μm or more were generated on the surface of the pattern, and the pattern could not be formed. Therefore,
Although the content of the dissolution inhibitor was set to 5%, the surface still looked cloudy (innumerable holes were formed), and the patterning was possible only when the content was 3%. The line width of the obtained pattern was 0.6 μm, and its cross section was triangular. Comparative Examples 4 to 6 Components similar to those in Comparative Example 3 were mixed with the same composition as in Examples 43, 49 and 56 to prepare resist solutions. When each of the obtained resist solutions was applied to a substrate and evaluated in the same manner, pattern formation could not be performed for the same reason as described above. Further, when the proportion of the dissolution inhibiting group was reduced, the cross-sectional shape of the pattern became triangular, and in any case, a pattern having a rectangular cross-section could not be obtained.

[0112]

As described in detail above, according to the present invention,
A photosensitive composition having high sensitivity and high resolution particularly for a light source of a short wavelength and capable of forming a fine resist pattern having a rectangular cross section is provided. Such a photosensitive composition and the formation of a pattern using the same exhibit a remarkable effect in the photolithography technique of the semiconductor device manufacturing process, and their industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for forming a pattern using the photosensitive composition of the present invention.

[Explanation of symbols]

1 ... Substrate, 2 ... Small polarity component, 3 ... Solvent, 4 ... Large polarity component 5 ... Photosensitizer, 6 ... Resist film, 7 ... Mask, 8 ... Exposure light, 9 ... Pattern.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Rio Hayashi 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research and Development Center (72) Inventor Rumiko Hayase Komukai-Toshiba, Kawasaki-shi, Kanagawa Town No. 1 Incorporated Toshiba Corporation R & D Center (72) Inventor Hirokazu Niki Komukai Toshiba Town No. 1, Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture

Claims (4)

[Claims] 1. A photosensitive composition comprising a compound which is decomposed by an acid and becomes soluble in an alkaline solution, and a compound which generates an acid when irradiated with light, the composition being decomposed by the acid to be an alkaline solution. The photosensitive composition is characterized in that the soluble compound contains a component having a small molecule polarity and a slow alkali dissolution rate, and a component having a large molecule polarity and a high alkali dissolution rate. 2. A photosensitive composition comprising a compound that is decomposed by an acid and becomes soluble in an alkaline solution, and a compound that generates an acid when irradiated with light, the composition being decomposed by the acid to be an alkaline solution. The compound to be soluble includes a component having a small molecule polarity and a slow alkali dissolution rate, and a component having a large molecule polarity and a high alkali dissolution rate, and the molecule having a small polarity and a slow alkali dissolution rate is 20% or more of the alkali-soluble group is protected by an acid-decomposable group, is a polymer compound having a weight average molecular weight of 5,000 or more, and the component having a large polarity of the molecule and a high alkali dissolution rate is the alkali-soluble group. Less than 20% of the compound is protected by an acid-decomposable group, and the compound has a weight average molecular weight of less than 10,000. 3. A photosensitive composition comprising a compound that is decomposed by an acid and becomes soluble in an alkaline solution, and a compound that generates an acid when irradiated with light, the composition being decomposed by the acid to be an alkaline solution. The compound to be soluble includes a component having a small molecule polarity and a low alkali dissolution rate, and a component having a large molecule polarity and a high alkali dissolution rate, and having a small molecule polarity and a low alkali dissolution rate, A compound having a substituent in which a phenol group is protected by an acid-decomposable group, wherein the component having a large polarity of the molecule and having a high alkali dissolution rate is a compound having a substituent in which a carboxyl group is protected by an acid-decomposable group. And a photosensitive composition. 4. A compound containing a compound that is soluble in an alkaline solution when decomposed by an acid and a compound that generates an acid when irradiated with light, and the compound that is soluble in an alkaline solution when decomposed by the acid is: A step of forming on the substrate a photosensitive composition containing a component having a small molecule polarity and a low alkali dissolution rate, and a component having a large molecule polarity and a high alkali dissolution rate;
The method comprises pattern-exposing the photosensitive composition into a predetermined shape, baking the exposed photosensitive composition, and developing the baked photosensitive composition with an alkaline solution. Pattern forming method.