KR0148624B1 - Photosensitive composition and pattern forming method using the same - Google Patents

Abstract

The present invention relates to photosensitive compositions suitable for resist materials. This photosensitive composition has a short wavelength, has high photosensitivity and resolution with respect to a light source, does not induce phase separation in a film state, and can stably form a micro resist pattern. The photosensitive composition is a polymer obtained by protecting an alkali soluble group of an alkali-soluble polymer with an unstable group against an acid, a compound which forms an acid upon irradiation with light, and an imidazole compound, an alanine compound, an adenine compound, an adenosine compound, and a quaternary ammonium salt compound It comprises one or more compounds selected from the group consisting of and which improve the miscibility in the resist film.

Description

Photosensitive composition and pattern formation method using the same

1 is a view showing the shape of the pattern formed using the photosensitive composition of the present invention,

2 is a view showing the shape of the pattern formed by utilizing the photosensitive composition of the present invention,

3a and 3b is a view showing the shape of a pattern formed using a conventional photosensitive composition,

4 is a graph showing the dependence of the standing time of the photosensitive composition of the present invention.

* Explanation of symbols for main parts of the drawings

1,3,5 Base material 7: Exposed part

2,4,6 Resist Pattern 8: Protective Film

9: poorly soluble layer of protrusion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photosensitive compositions and pattern forming methods for use in the formation of micropatterns in semiconductor devices, particularly large scale integrated circuits (LSIs).

As semiconductor devices such as LSIs are manufactured, a micropattern forming method performed by photolithography has been used. This technique is performed in the following manner. That is, a photoresist film is first formed on a substrate such as a silicon single crystal wafer by, for example, a spin coating method, and then the film is exposed. Subsequently, a resist pattern is formed by performing a process such as development and rinsing on the resist film. Thus, by etching the exposed wafer surface using a resist pattern as an anti-etching mask, lines and windows of a predetermined width are formed, thereby forming a desired pattern.

In the production of LSI, as the packing density of LSI increases, a treatment method capable of forming a finer pattern in the lithography method is required. In order to meet these requirements, there have been attempts to shorten the wavelength of an exposure light source. In one such attempt, a lithographic technique using strong ultraviolet light such as KrF excimer laser (wavelength 248 nm) or ArF excimer laser (wavelength 193 nm) as a light source was examined.

However, conventional resist materials are excessively high in absorbing strong ultraviolet light. Thus, ultraviolet light cannot sufficiently reach a portion away from the surface of the resist film (eg, the interface region between the resist film and the substrate) during exposure. Thus, chemical changes due to exposure over the total film thickness of the exposed portion of the resist film are not satisfactory. As a result, the resolution in accordance with the thickness associated with the developer is uneven. As described above, in particular, the resolution of the portion separated from the surface of the resist film is low, so after development, the partial shape in the portion of the formed resist pattern becomes a triangle. Problems arise when the resist pattern thus formed is used as an anti-etching mask; That is, the micropattern cannot be transferred to the substrate or the like.

As a resist material that can solve the above problem, a resist called a chemically amplified resist has been proposed. A chemically amplified resist is a photosensitive composition containing a compound that forms a strong acid when irradiated with light, that is, a photo-acid generator, and a compound that turns into a hydrophilic material when the hydrophobic group is decomposed by the generated acid. to be. As an example of such a material, H. Ito, G.G. Wilson and JMJ Freche, U.S. Patent No. 4,491,628 (1985), disclose a polymer obtained by shielding a hydroxyl group of a poly (p-hydroxystyrene) with butoxycarbonyl groups, and an onium salt as a photo-acid generator. A positive resist containing is disclosed. In addition, M. J. O'Brien, J. V. Cribel, SPIE, Volume 920 Advances in Resist Technology and Processing, p. 42 (1988) discloses a positive resist containing m-cresol novolak resin, naphthalene-2-carboxylic acid-t-butylester, and triphenyl sulfonium rows as photo-acid generators. See also H. Ito, SPIE, Volume 920, Advances in Resist Technology and Processing, p. 33 (1988) discloses a positive resist containing 2,2-bis (4-t-butoxycarbonyloxyphenyl) propane or polyphthalaldehyde and an onium salt as a photo-acid generator.

In each of these chemically amplified resists, the acid formed by the photo-acid generator acts as a catalyst, effectively causing chemical changes in the resist even in small amounts. Therefore, when the resist film is exposed, the reaction is sufficiently carried out even inside the film where radiation is hard to reach as compared to the film surface. As a result, a resist pattern having a rectangular cross section after development, specifically, a resist pattern having a steep and vertical side of the line portion can be formed.

However, in the chemically amplified resist, the amount of acid formed in the exposed portion of the resist film is very small. Therefore, the resist is easily affected by the surrounding environment, in particular, oxygen and moisture in the atmosphere and other trace components in the atmosphere on the surface of the resist film. As a result, it is difficult to stably form a minute pattern. More specifically, trace amounts of dimethylaniline contained in the atmosphere deactivate the acid formed near the surface of the resist film upon irradiation. As a result, a so-called poorly soluble layer having a very low dissolution rate associated with a developer is formed on the resist film surface. This poorly soluble layer has been reported to remain as a protrusion on the surface of the resist pattern after exposure and development (SA McDonald, NJ Cleark, HR Wort, CG Wilson, CD Snyder, CJ Knorr, NB Bode, JG Maltabe, JR Morrow, AE McGuire, and SJ Hipples, Proc. SPIE, Vol. 1466, 2 (1991).

This poorly soluble layer lowers the solubility of the resist, and the protrusions formed on the resist pattern by the poorly soluble layer affect the etching precision of the semiconductor substrate region. As shown in FIG. 3A, in order to prevent the formation of this protruding poorly soluble layer, a protective layer 8 is formed on the resist film to mitigate the atmospheric influence and then expose it (Japanese Patent Application Laid-Open No. 4- 204084). However, even in this method, the protrusion could not be completely removed, and as shown in FIG. 3B, the protruding poorly soluble layer 9 was formed on the sidewall of the resist pattern 6. This method of forming the protective layer has other problems besides the above problems; That is, the method requires an additional coating device because the number of processes increases, and the working efficiency is lowered.

On the other hand, it is known that the resolution can be increased by adding arbitrary anilines, imidazoles, pyridines, and ammonia derivatives to the chemically amplified resist composition. (Japanese Patent Application Laid-open No. 5-127369). However, the compatibility of amine-like compounds with low-molecular weight compounds (which will be described later) has not been published.

In addition, in the formation of the pattern using the chemically amplified resist, when the resist film is formed, that is, when the resist solution is coated on the substrate, the phase is often separated in the film due to the molecular weight difference between the components, whereby the concentration of each component The distribution is nonuniform. As a result, the chemical change in the exposed portion of the film does not proceed uniformly, whereby a micro resist pattern having a rectangular cross-sectional shape cannot be obtained stably.

Phase separation was performed by H. Ito, J. Polymer. More specifically described in Sci: Part A 24, 2971 (1986), wherein polyvinyl phenol is used as a component of the resist material, in which the phenolic hydroxyl group is partially protected by t-butoxycarbonyl It was reported that the phase separation takes place depending on the rate of introduction of the protecting groups of the polymer in the synthesis of. The concentration distribution of the components in the resist film is described in M. Toriumi, M. Anajimachi, and M. Mashara, Proc. SPIE. Vol. 1466, 458 (1991).

In pattern formation using chemically amplified resists, the width of the line varies with the post-exposure bake temperature, which is known to reduce photosensitivity (J. Sterthevant, S. Holmes, P. Lablidu). Advances in Resist Technology and Processing IX, SPIE, Vol. 1672, 114 (1992). Therefore, it is necessary to precisely control the heat treatment temperature that causes poor work efficiency.

The present invention has been made in consideration of the above situation, and especially for light sources with short wavelengths, high photosensitivity and resolution, do not cause phase separation in the film state, are not easily affected by ambient atmosphere, and stably form a micro resist pattern An object of the present invention is to provide a photosensitive composition.

The object of the present invention can be achieved by the following photosensitive compositions of the first and second invention.

Polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer with an acid labile group of the photosensitive composition of the first invention, a compound (b) which generates an acid upon irradiation, and an imidazole compound, an alanine compound, an adenine compound At least one compound (c) selected from the group consisting of adenosine compounds, and quaternary ammonium salt compounds, which improves miscibility in the resist film.

The photosensitive composition of the second invention contains a polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer with an acid labile group, a compound (b) generating an acid upon irradiation, and a phenol compound (d) do.

In addition, the photosensitive composition of the third invention is a polymer obtained by protecting an alkali-soluble group of an alkali-soluble polymer with an unstable group against an acid (a), a compound which generates an acid upon irradiation (b), an imidazole compound, an alanine compound At least one compound (c) which is selected from the group consisting of adenine compounds, adenosine compounds, and quaternary ammonium salt compounds and which improves miscibility in the resist film, and phenolic compounds (d).

The manufacturing method of the present invention comprises the steps of: generating a resin layer containing any photosensitive composition of the first, second, and third invention as a main component on a substrate; performing pattern exposure to the resin layer; Heat-treating the resin layer, and developing the heat-treated resin layer using an alkaline solution as a developer.

The photosensitive composition of the present invention corresponds to a chemically amplified resist. That is, when this photosensitive composition is used in the patterning method, an acid is formed from component (b) in the exposed portion of the photosensitive composition. In the heat treatment, this acid acts as a catalyst to decompose the group contained in component (a) and unstable to the acid, thus making the group an alkali-soluble group. As a result, the alkali solubility, that is, the dissolution rate for the alkaline solution, is raised in component (a) in this exposed portion. Therefore, the exposed part is selectively dissolved and separated by developing using an alkaline solution. As a result, a micro pattern composed of lines and spaces of a predetermined width can be manufactured.

The photosensitive composition of the first invention comprises at least one compound selected from the group consisting of component (c), that is, an imidazole compound, an alanine compound, an adenine compound, an adenoic acid compound, and a quaternary ammonium salt compound, in addition to the components (a) and (b) It contains. In this photosensitive composition, the binary component (c) increases solubility by acting as a base for the acid generated by irradiation. Component (c) also increases the miscibility between the polymer of component (a) and the low molecular weight compound of component (b). This prevents phase separation in the film substrate. Therefore, the concentration distribution of each component is kept constant over the entire film, and the chemical change induced by exposure or the like proceeds evenly. In the present invention, the micropattern is formed by such a high miscibility effect. In addition, component (c) increases the alkali solubility in the exposed portion of the film, so that formation of the protruding poorly soluble layer can be prevented without forming any protective film on the resist film. In addition, when the period from the exposure to the heat treatment performed by the heat treatment is extended during the pattern formation process, the photosensitive composition of the first invention controls the diffusion of the acid formed by the exposure, whereby a micro pattern can be formed.

Accordingly, the photosensitive composition of the first invention maintains its inherent resolution and its high photosensitivity in chemically amplified resists, and is stable over the entire pattern formation process and provides a micropattern having a rectangular cross-sectional shape. As described above, the first invention does not require the use of the protective film required for the conventional chemically amplified resist. In addition, the protective film forming step can be omitted, which reduces the total number of steps in the manufacturing process.

The second photosensitive composition of the present invention comprises a polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer with an unstable group against an acid, a compound (b) generating an acid upon irradiation, and a phenol compound (d). It is a composition to contain.

This second photosensitive composition also corresponds to a positive chemically amplified resist. Thus, when used in the pattern forming method, the second photosensitive composition provides a fine pattern according to the same mechanism as in the first composition.

The second photosensitive composition contains component (d), that is, a phenol compound, in addition to components (a) and (b). In the second photosensitive composition, this phenolic compound increases the miscibility between the polymer (a) and the low molecular weight compound (b). For this reason, as in the first composition, phase separation does not occur in the film state, the concentration distribution of each component is kept constant over the entire film, and the chemical change caused by exposure or the like proceeds evenly. In particular, in the second photosensitive composition, the hydroxyl group contained in the phenol compound is not protected and reacts with the alkali-soluble group remaining in the polymer as component (a), thereby preventing separation of the high molecular weight component (a). Is assumed. In addition, since the phenolic compound raises the alkali solubility in the exposed portion of the film, the alkali solubility of the resist film can be increased compared to the solubility of the conventional resist film. Therefore, formation of a poorly soluble layer on the film surface can be prevented. In addition, since the photosensitive composition of the second invention has a large focal range, a micro pattern may be formed even when an error in focus control occurs during exposure. This can increase work efficiency. The second photosensitive composition is also used in conventional chemically amplified resists by controlling the amount of at least one compound selected from the group consisting of photo-acid generators and imidazole compounds, alanine compounds, adenine compounds, adenosine compounds, and quaternary ammonium salt compounds. The use of the required protective film can be omitted.

As described above, the second photosensitive composition of the present invention maintains the inherent resolution and high photosensitivity in the chemically amplified resist, is stable throughout the entire patterning process, and provides a micropattern having a rectangular cross section.

The photosensitive composition of the third invention contains a phenol compound as component (d) in addition to components (a), (b) and (c) of the first composition. Components (c) and (d) also improve the miscibility between the polymer (a) and the low molecular weight compound (b), so that phase separation in the film state can be prevented. In addition, the combination of components (c) and (d) significantly increases the dissolution rate in the alkaline solution in the exposed portion of the film. This prevents the formation of a sparingly soluble layer on the film surface, and also makes a clear difference between the exposed and unexposed portions.

The photosensitive composition of the third invention maintains inherent resolution and high photosensitivity in chemically amplified resists and is more stable than the composition of the first invention over the entire pattern formation process. As a result, the third photosensitive composition provides a micropattern with a rectangular cross section, which prevents the formation of a protruding sparingly soluble layer on the film surface, and also a standing-wave effect on the side of the film. (The standing wave effect is the effect of forming a wavelength having a predetermined period on the side surface of the resist because the energy stored in the resist film varies depending on the depth of the resist film due to the reflection of the exposure light from the resist surface. Interference of light components reflected by the surface of the substrate).

In the case of using the photosensitive composition of the third invention, the use of a protective film may also be unnecessary. Thus, since the protective film forming step can be omitted, the total number of steps in the manufacturing process can be reduced.

The present invention also provides a pattern forming method using any of the first, second, and third photosensitive compositions described above. That is, the pattern forming method of the present invention comprises the steps of forming a resin layer containing any one of the first, second and third photosensitive compositions as a main component on a substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat treated resin layer using an alkaline solution as a developer.

In the pattern formation method of the present invention, since the sensitivity does not change when the heat treatment temperature is changed, the working efficiency may be increased.

Hereinafter, the present invention will be described in detail.

In the photosensitive composition of the first invention, the polymer as component (a) uses an alkali-soluble polymer as the base polymer and an alkali-soluble group in the base polymer, for example, a phenolic hydroxy group or a carboxyl group, which is unstable to acids. Protecting group) to inhibit the alkali affinity of the polymer. The polymer is almost insoluble in alkaline solution in the unexposed state. However, when exposed to light, the polymer turns into an alkali soluble compound, since the protecting group is deprotected by the acid generated by component (b) to regenerate the alkali-soluble groups originally possessed by the base polymer. to be. It should be noted that the molecular weight of the polymer is preferably about 1,000 or more to improve heat resistance.

As said polymer which is component (a), ether or ester containing the alkali-soluble polymer which has a phenol skeleton as a base polymer can be used preferably. An example of such a polymer is a compound obtained by etherifying or esterifying a phenolic hydroxy group of a polymer having a phenol skeleton with an appropriate etherification or esterification agent to protect the phenolic hydroxy group.

Examples of alkali-soluble polymers having a phenol skeleton include phenol, cresol, xylenol, bisphenol A, bisphenol S, hydroxybenzophenone, 3,3,3 ', 3'-tetramethyl-1 as its monomeric units. Polymer with 1'-spirobiindane-5,6,7,5 ', 6', 7'-hexanol, or phenolphthalein; Polyvinyl phenol; And novolak resins.

Examples of ethers and esters to be introduced as protecting groups in alkali-soluble polymers having a phenol skeleton include tetrahydropyranyl ether, benzyl ether, methyl ether, ethyl ether, n-propyl ether, iso-propyl ether and t-butyl ether. , Allyl ether, methoxymethyl ether, p-bromophenacyl ether, trimethylsilyl ether, benzyloxycarbonyl ether, t-butoxycarbonyl ether, t-butyl acetate, 4-t-butylbenzyl ether, methyl ester , Ethyl ester, n-propyl ester, iso-propyl ester, t-butyl ester, n-butyl ester, isobutyl ester, and benzyl ester.

In the polymer, not all of the phenolic hydroxy groups contained in the base polymer are protected, but some remain unprotected in the polymer. Therefore, the polymer is essentially a copolymer consisting of monomer units having ether or ester introduced therein and monomer units having phenolic hydroxy groups.

The most preferable example of a polymer as component (a) is a compound represented by following formula (1)-(4);

In the formulas, R ¹ , R ² and R ³ each represent a monovalent organic group, and m and n each represent a copolymer composition. The monovalent organic group is not particularly limited. Examples of such primary groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, t-butyl, iso-butyl, secondary-butyl, and benzyl.

The mixing amount of component (a) is preferably 5-80% by weight, more preferably 10-60% by weight relative to the total solids content of the composition.

In the photosensitive composition of the first invention, component (b) is a compound which generates an acid upon exposure and corresponds to a photo-acid generator of a chemically amplified resist. Mixtures with compounds known as photo-acid generators, for example onium salts, organic halogen compounds, autoquinone-diazide sulfonic acid chlorides, and sulfonates can be used as such compounds.

The onium salt is not particularly limited. Examples of onium salts include diazonium salts, phosphonium salts, sulfonium salts, and iodonium salts, which are respectively CF ₃ SO ₃ ⁻ , p-CH ₃ PhSO ₃ ⁻ , or p-NO ₂ PhSO as counter anions. ^₃ has a (wherein, Ph represents a phenyl group).

The organic halogen compound is a compound that forms a hydrohalide acid. Examples of such compounds are disclosed in US Pat. Nos. 3,515,552, 3,536,489, and 3,779,778, and West German Patent 2,243,621.

Examples of photo-acid generators other than those listed above include Japanese Patent Application Laid-Open Nos. 54-74728, 55-24113, 55-77742, 60-3626, 60-138539, 56-17345, And the compounds disclosed in 50-36209.

Examples of such compounds include di (pt-butylbenzene) iodonium trifluoromethanesulfonate, diphenyliodonium trifluoromethanesulfonate, benzointosylate autonitrobenzyl paratoluenesulfonate, triphenyl Sulfonium trifluoromethanesulfonate, tri (t-butylphenyl) sulfonium trifluoromethane sulfonate, benzenediazonium paratoluenesulfonate, 4- (di-n-propylamino) -benzonium tetrafluoroborate , 4-p-tolyl-mercapto-2, 5-diethoxybenzenediazonium hexafluorophosphate, tetrafluoroborate, diphenylamine-4-diazonium sulfate, 4-methyl-6-trichloromethyl-2 -Pyron, 4- (3,4,5-trimethoxystyryl) -6-trichloromethyl-2-pyron, 4- (4-methoxystyryl) -6- (3,3,3-trichloro Loprophenyl) -2-pyrone,

2-trichloromethylbenzimidazole, 2-tribromomethylquinoline, 2,4-dimethyl-1-tribromoacetylbenzene, 4-dibromoacetylbenzoic acid, 1,4-bis-dibromomethylbenzene ,

Tris-dibromomethyl-S-triazine, 2- (6-methoxy naphth-2-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (naphth-1- Il) -4,6-bis-trichloromethyl-S-triazine, 2- (naphth-2-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (4-e Methoxy ethylnaphth-1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (benzopyran-3-yl) -4,6-bis-trichloromethyl-S-triazine , 2- (4-methoxyanthracen-1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (phenanth-9-yl) -4,6-bis-trichloromethyl -S- triazine, and o-naphthoquinonediazide-4-sulfonic acid chloride.

Examples of sulfonates include naphthoquinone diazido-4-sulfonic acid esters, naphthoquinone diazido-5-sulfonic acid esters, o-nitrobenzyl p-toluenesulconate and 2,6-dinitrobenzyl p Toluenesulfonate.

The mixing amount of component (b) is preferably about 0.001 to 50% by weight, more preferably 0.1 to 10% by weight based on the total solids content of the composition. When the mixing amount of the component (b) is 0.01% by weight or less, it may be difficult to obtain sufficient photosensitivity. On the other hand, when the mixing amount is 50% by weight or more, it may be difficult to form a uniform resist film, that is, may remain on the back side in the residue during the removal step performed after the pattern forming step.

In the photosensitive composition of the first invention, component (c) is a compound that increases the miscibility in the resist film. The compound is selected from imidazole compounds, alanine compounds, adenine compounds, adenosine compounds, and quaternary ammonium salt compounds.

The imidazole compound is an imidazole or derivative thereof. Specific examples of the imidazole compound are compounds represented by the following general formula (5), but the imidazole compound is not limited to the above embodiments:

Wherein R ⁴ is a monovalent organic group.

Alanine compounds are alanine or derivatives thereof. Specific examples of the alanine compound are compounds represented by the following general formula (6), but the alanine compound is not limited to the above embodiments:

In the above formula, R ⁵ is a monovalent organic compound.

Adenine compounds are adenine or derivatives thereof. Examples of the adenine compound are compounds represented by the following general formulas (7) and (8), but the adenine compound is not limited to the above embodiments:

In the above formula, R ⁶ and R ⁷ each represent a monovalent organic group.

Adenosine compounds are adenosine or derivatives thereof. Specific examples of the adenosine compound are compounds represented by the following general formula (9), but the adezocin compound is not limited to the above embodiments:

In the above formula, R ⁸ represents a monovalent organic group.

In the compounds represented by the general formulas (5) to (9), the monovalent organic group introduced as any one of R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ is not particularly limited. Examples of such monovalent organic groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, secondary-butyl, and benzyl.

Quaternary ammonium salt compounds are quaternary ammonium salts or derivatives thereof. Specific examples of the quaternary ammonium salt compound are compounds represented by the following general formula (10), but the quaternary ammonium salt compound is not limited to the above embodiments:

_{^{N (R 9) 4 · X}} (10)

Wherein R ⁹ is a monovalent organic group and X is also a monovalent organic group. For example, it is a hydroxyl group etc. of X, and it is preferable that it is a hydroxyl group.

In the first photosensitive composition of the present invention, the mixing amount of component (c) is preferably about 0.01 to 50% by weight, more preferably 0.1 to 30% by weight based on the total solids content of the composition. When the mixing amount of the component (c) is 50% by weight or more, the distribution of the photosensitive composition changes or cancels in the resist film; In other words, miscibility becomes inferior. When the mixing amount of component (c) is 0.01% by weight or less, after development, residues may remain on the back surface to roughen the surface of the formed pattern. On the other hand, a blending amount of at least 50% by weight reduces the difference in dissolution rate for the alkaline solution between the exposed and unexposed portions of the zelist film, which can lower the resolution. The mixing of the component (c) allows exposure in the state shown in FIG. 1 without using a protective film (usually indicated by reference numeral 8 in FIG. 3a) which is usually required, The protective film coating step is unnecessary.

Hereinafter, to describe the second photosensitive composition of the present invention.

In the second photosensitive composition, the components (a) and (b) are the same as in the composition described above.

The phenol compound as component (d) is a compound having a phenol skeleton, that is, a phenolic hydroxy group in its structure. The phenolic compound has a lower molecular weight than ethers or esters using polymers as component (a), in particular polymers having a phenol skeleton as base polymer.

The phenolic compound increases the miscibility between the polymer as component (a) and the low molecular weight compound as component (b).

It should be noted that the molecular weight of the polymer is preferably about 1000 or more in order to improve the miscibility between the polymers.

Specific examples of the phenol compound include compounds represented by the following general formulas (11), (12) and (13) and polyvinyl phenols represented by the following general formula (14). Among these compounds, particular preference is given to triphenol compounds, ie compounds having three phenolic hydroxy groups. In the case of polyvinyl phenol represented by the following general formula (14), Preferably has a molecular weight smaller than the base polymer having a phenol skeleton.

Wherein R ¹⁰ is hydrogen, CH ₃ ;

R ¹¹ , R ¹² are CH ₃ , C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ to be.

In the second photosensitive composition according to the present invention, the mixing amount of component (d) is preferably about 0.01-50% by weight, more preferably 0.1-10% by weight relative to the total solids content of the composition. When the mixing amount of the component (d) is 0.01% by weight or less, it may become difficult to obtain sufficient photosensitivity. When the mixing amount is 50% by weight or more, it may be difficult to form a uniform resist film.

According to the second invention as described above, since the standing wave effect is eliminated by the addition of the component (d), it is possible to form a vertical clear pattern as shown in FIG. Also, as in the first invention, the number of manufacturing steps can be reduced since it is not necessary to use a protective film ((8) in FIG. 3A).

The photosensitive composition of the third invention contains a phenol compound as component (d) in addition to components (a), (b) and (c) of the first composition of the present invention.

The components (a), (b), (c) and (d) are all the same as described above.

In the photosensitive composition of the third invention, the mixing amount of component (d) is preferably about 0.01-50% by weight and more preferably 0.1-10% by weight relative to the total solids content of the composition. When the mixing amount of the component (d) is 0.1% by weight or less, it may be difficult to suppress sufficient photosensitivity. When the mixing amount exceeds 50 wt%, it may be difficult to form a uniform resist film.

In the photosensitive composition of the third invention, the mixing amount of the components (a), (b) and (c) is preferably 10-60% by weight, 0.1-10% by weight, and 5-50% by weight, respectively.

In addition to the essential components mentioned above, the photosensitive composition of this invention can contain surfactant as a film modifier, dye as a reflector, etc. as needed.

The photosensitive composition of the present invention can be prepared by dissolving the essential components as described above and, if necessary, other additives in a suitable organic solvent and filtering the formed solution. Examples of the organic solvent include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone; Cellosolve type solvents such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, ethyl cellosolve acetate, butyl cellosolve, and butyl cellosolve acetate; Ester solvents such as ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, and methyllactate; And N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. These solvents may be used alone or in the form of mixtures. The solvents may also contain appropriate amounts of aliphatic alcohols such as xylene, toluene, or isopropyl alcohol.

Hereinafter, a method of forming a resist pattern using the photosensitive composition of the present invention will be described.

First, the photosensitive composition solution prepared by dissolving the components in an organic solvent is coated on a substrate by a rotary coating method or a dipping method, and then the composition is dried by drying at about 150 ° C. or less, preferably 70-120 ° C. The photosensitive resin layer (resist film) which has a main component is formed. Examples of substrates used herein include, for example, silicon wafers, silicon wafers with various insulating film collisions, electrodes and interconnects on their surfaces, blank masks, and III-V compound semiconductor wafers, for example composed of GaAs or AlGaAs. to be.

Subsequently, a pattern step is performed on the resist film. In this exposure step, component (b) of the photosensitive composition generates acid in the exposed portion of the resist film.

As a light source used in this exposure step, i-, h-, or g-line of a low pressure mercury lamp, xenon lamp light, various ultraviolet rays, such as strong UV, X-ray, electron beam, γ, such as KrF or ArF aximmer laser -Ray or ion beam can be used. In the case where ultraviolet or X-rays are to be used, the pattern exposing step is performed by selectively exposing the resist film through a predetermined mask pattern. On the other hand, in the case where an electron beam or an ion beam is to be used, the pattern exposure step is performed directly on the resist film by scanning the radiation without using a mask at all. In order to improve the resolution by lowering the dissolution rate in the unexposed portions, a fog exposure may be performed to expose the entire surface of the resist film while heating the exposed portions of the pattern.

Subsequently, the exposed resist film is heat-treated by using a hot plate or an oven or by irradiating with infrared rays. In this heat treatment step, the acid formed by exposure diffuses and acts on the polymer that is component (a) in the exposed portion of the resist film. As a result, the introduced protecting group is decomposed so that the alkali-soluble group is regenerated.

The heat treatment temperature is preferably about 50-160 ° C, more preferably 70-150 ° C. When the heat treatment temperature is 50 ° C. or lower, there is a possibility that the acid generated by the component (b) cannot sufficiently react with the component (a). When the heat treatment temperature is 160 ° C. or more, excessive decomposition or curing may occur over exposed and unexposed portions of the resist film.

The heat treated resist film is then developed using an alkaline solution according to the dipping method or spraying method. This selectively dissolves away the exposed portions of the resist film, yielding a predetermined pattern. Examples of the alkaline solution used as the developer may include inorganic alkaline solutions, such as aqueous solutions of potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, and sodium methsilicate, aqueous tetramethylammonium hydroxide, aqueous trimethylhydroxyethylammonium hydroxide solution, and And solutions prepared by adding alcohols, surfactants, and the like to aqueous solutions. As the organic solvent, for example, xylene or isopropyl alcohol can be used.

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

In the above method, for the purpose of improving the heat resistance of the resist pattern, after the developing step, the substrate is gradually heated to crosslink the resin component (polymer as component (a)) contained in the resist pattern, or while the substrate is heated. By irradiating strong UV, it is possible to carry out a treatment such as a strong UV curing step of crosslinking the resin component (polymer as component (a)) contained in the resist pattern.

In addition, to reduce the alkali dissolution rate in the unexposed portions of the resist pattern to improve the contrast between the exposed and unexposed portions, the resist film is immersed in a low concentration alkali solution before or after the exposure step and then with high concentration alkali solution. The development stage may be compromised. In this case, it can be immersed in amines such as triethylamine, triethanolamine, or hexamethyldisilazane, or exposed to the vapor of either of the amines instead of the low concentration alkali solution of the resist film. In addition, heat treatment may be performed on the resist film immersed in a low concentration alkali solution or exposed to amines.

EXAMPLE

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are provided to aid the understanding of the present invention, and are not intended to specifically limit the present invention as examples.

[Synthesis of Polymers with Unstable Groups to Acids]

Dissolve 50 g of polyvinylphenol (PHM-C: Maruzen Sekiyu Kagaku Co., Ltd.) in 200 ml acetone in a four-necked flask, 17.63 g of potassium carbonate, 8.48 g of potassium iodide, and 24.38 g of t- Butyl bromoacetate was dissolved in the solution. The resulting solution was stirred at reflux for 7 hours. Undissolved components were removed by filtration, acetone was removed by evaporation and the residue was dissolved in 150 ml of ethanol. The resulting solution was added dropwise to 1.5 ml of water to precipitate the polymer. The polymer was separated by filtration, washed five times with 300 ml of water and then dried for 4 x 12 hours. The dried polymer was then dissolved again in 230 ml of ethanol and precipitated and purified in the same manner as described above. The resulting material was dried in a vacuum drier at 50 ° C. for 24 hours to yield 52.0 g of polymer.

Analysis of the obtained polymer by ¹ H-NMR spectrum revealed that the polymer was a compound in which 15% of all phenolic hydroxylations of polyvinylphenol were converted to t-butoxycarbonylmethyl ether. The said polymer was represented by [T-1].

According to the same procedure as described above, by appropriately adjusting the mixing amount of potassium carbonate, potassium iodide, and t-butyl bromoacetate, the ratio of substitution of phenolic hydroxyl groups in the polyvinylphenol, that is, the ratio of ether introduction is different. Eight types of polymers [T-2] to [T-9] were synthesized.

The structure and composition of the polymer is shown in Table 1 below.

[Example 1-48]

(1) Preparation of the photosensitive composition which consists of a polymer, onium salt, and an amine compound in which a group unstable to an acid is introduced.

According to the formulation shown in Table 2 below, the polymer into which the labile group was introduced for the acid, the onium salt (triphenylsulfonyl trifolate) as a photo-acid former, and the amine compound were dissolved in a solvent. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare varnish photosensitive compositions [R-1] to [R-48].

In the preparation of the photosensitive composition, an imidazole compound (one of A-1 to A-3) is mixed with the composition [R-1] to [R-9], and the composition [R-10] to [R-21] ] Are mixed with an alanine compound (A-4 or A-5), adenine compound (A-6 or A-7) is mixed with compositions [R-22] to [R-23], and the composition [R-34] ] And [R-39] were mixed with the adenosine compound (A-8), and the quaternary ammonium salt compound (A-9) was mixed with the composition [R-40]-[R-48].

General formulas of the imidazole compound, the alanine compound, the adenine compound, the adenosine compound, and the quaternary ammonium salt compound are represented by symbols, respectively, and are shown in the following table.

(2) pattern formation

The photosensitive composition (varnish) prepared as described above was spin coated with a 6-inch silicone wafer. The resulting wafers were previously heat treated at 95 ° C. for 90 seconds on a hot plate to form a 1.0 μm thick photosensitive composition film (resist film). The pattern was then exposed to the resist film using a KrF excimer laser stepper and the resulting wafers were heat treated at 95 ° C. for 90 seconds on a hot plate. Thereafter, the heat treated wafer was immersed in 1.59% aqueous tetramethylammonium hydroxide solution (TMAH aqueous solution) for 20 seconds to develop a resist film. The resulting wafers were then washed and dried to give a pattern consisting of lines and spaces.

Scanning electron microscopy was used to observe the shape of each part of the generated pattern, and the width of the line and space was measured as a measure of the resolution.

Table 3 below shows the exposure amount (sensitivity) and resolution of the photosensitive composition obtained in each example.

Although the alkaline solution was used as the developing solution in each example, the developing solution is not limited to the alkaline solution. As an example, other alkaline solutions or organic solvents can be used for development.

As apparent from the above results, the photosensitive compositions of the present invention each had high photosensitivity and high resolution. In addition, any pattern produced in the composition of the present invention had a rectangular cross section and steep side at the line portion.

In addition, when the patterns are formed using the compositions [R-1] to [R-48], the formation of the protruding solubility natural layer on the resist surface as shown in FIG. 1 can be reduced or eliminated. have. Therefore, a pattern can be formed without forming any protective film in the resist film.

Example 49-62

(1) Preparation of the photosensitive composition comprised from the polymer, the onium salt, and the phenolic compound which the group unstable to an acid was introduce | transduced, respectively.

According to the formulation shown in Table 4 below, the polymer into which the labile group was introduced for the acid, the onium salt (triphenylsulfonium tripulate) as a photo-acid forming agent, and the phenolic compound were dissolved in an organic solvent. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare varnish photosensitive compositions [R-49] to [R-62].

In the preparation of the photosensitive composition, a phenol compound (one of P-1 to P-7) was mixed with the compositions [R-49] to [R-62].

General formulas of the phenolic compounds are represented by symbols and shown in the following table.

(2) pattern formation

The photosensitive compositions (varnishes) prepared as described above were each spin coated onto 6-inch silicon wafers. The resulting wafer was preheated at 95 ° C. for 90 seconds on a hot plate to form a 1.0 μm thick photosensitive composition film (resist film). The pattern was then exposed to the resist film using a KrF excimer laser stepper and the resulting wafers were baked on a hot plate at 95 ° C. for 90 seconds. Thereafter, the heat treated wafer was immersed in 1.59% aqueous tetramethylammonium hydroxide solution (TMAH aqueous solution) for 20 seconds to develop a resist film. The resulting wafers were then washed and dried to give a pattern consisting of lines and spaces.

Scanning electron microscopy was used to observe the shape of each part of the generated pattern, and the width of the line and space was measured as a measure of the resolution.

Table 5 below shows the exposure amount (sensitivity) and resolution of the photosensitive composition obtained in each example.

As is apparent from the above results, each photosensitive composition of the present invention had high photosensitivity and high resolution. In addition, any pattern produced in the composition of the present invention had a rectangular cross section and steep side at the line portion.

In addition, when a pattern is formed using the compositions [R-49] to [R-62], it is possible to reduce or eliminate the formation of a protruding solubility retardation layer on the resist surface as shown in FIG. Can be. Therefore, a pattern can be formed without forming any protective film on a resist film.

Example 63-169

(1) Preparation of the photosensitive composition comprised from the polymer, the onium salt, the amine compound, and the phenol compound into which the group unstable to an acid was introduced.

According to the formulations shown in Table 6 below, polymers each having an unstable group introduced into an acid, onium salt as a photo-acid forming agent (triphenylsulfonium tripulate), a compound for increasing the miscibility in a resist film, and a phenol The compound was dissolved in an organic solvent. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare varnish photosensitive compositions [R-63] to [R-169].

In preparing the photosensitive composition, the compounds (P-1 to P-2) and the following compounds (P-8) used in Examples 49 to 62 were used as phenolic compounds. As the compound (P-8), polyvinylphenol having a molecular weight of approximately 6,000 was used. As an amine compound for increasing the miscibility of a resist film, an amidazole compound (A-1) is used in the compositions [R-63] to [R-82], and the compositions [R-83-] to [R-91] Another imidazole compound is used for the compound, and an alanine compound (A-4) is used for the compositions [R-92] to [R-111], and an adenine compound (A is used for the compositions [R-112] to [R-131]. -6 or A-7), an adenosine compound (A-8) was used for the compositions [R-132] to [R-151], and a quaternary to the compositions [R-152] to [R-169]. An ammonium salt compound (A-9) was used.

(2) pattern formation

Each photosensitive composition (varnish) prepared as described above was each spin coated with a 6-inch silicone wafer. The resulting wafers were pre-heated at a hot plate for 90 seconds at 95 ° C. to form a 1.0 μm thick photosensitive composition film (resist film). The pattern was then exposed to the resist film using a KrF excimer laser stepper and the resulting wafers were heat treated on a hot plate at 95 ° C. for 90 seconds. Thereafter, the heat treated wafer was immersed in 1.59% aqueous tetramethylammonium hydroxide solution (TMAH aqueous solution) for 20 seconds to develop a resist film. The resulting wafers were then washed and dried to give a pattern consisting of lines and spaces.

The scanning electron microscope was used to observe the cross-sectional shape of the generated patterns, respectively, and the width of the line and space was measured as a measure of the resolution.

Table 7 below shows the exposure amount (sensitivity) and resolution of the photosensitive composition obtained in each example.

As is apparent from the above results, the photosensitive compositions of the present invention each had high photosensitivity and high resolution. In addition, any pattern produced in the composition of the present invention had a rectangular cross section and steep side at the line portion.

In addition, when patterns are formed using the compositions [R-63] to [R-169], the formation of standing waves on each side of the pattern as shown in FIG. 1 can be reduced. Thus, the pattern can be formed with high accuracy.

Comparative Example 1

2.0 g of polymer [T-1] introduced with an acid labile group and 30 mg of onium salt (triphenylsulfonium tripulate) as a photo-acid formation were dissolved in 6.00 g of ethylcellosolve acetate. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a varnish photosensitive composition [R-170].

According to the same methods and conditions as in the above Example, a pattern was formed using the photosensitive composition [T-170].

The cross-sectional shape of the resulting pattern was observed using a scanning electron microscope to measure the width of the acid and the space as a measure of the resolution. As a result, the resolution was 0.35 mu m for an exposure dose of 40 mJ / cm 2. However, a poorly soluble layer of protruding shape was formed on the surface layer of the pattern. This is because neither the specific phenolic compound nor the specific amine compound, as used in the above examples, is assumed to be mixed in the photosensitive composition [R-170].

Comparative Example 2

2.0 g of polymer [T-5] introduced with an acid labile group and 30 mg of onium salt (triphenylsulfonium trifolate) as a photo-acid formation were dissolved in 6.00 g of methimethoxy propionate. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a varnish-type photosensitive composition [R-171].

According to the same methods and conditions as in the above Example, a pattern was formed using the photosensitive composition [T-171].

Partial morphology of the resulting pattern was observed using a scanning electron microscope to measure the width of the acid and space as a measure of the resolution. As a result, the resolution was 0.40 mu m for an exposure amount of 43 mJ / cm 2. However, protruding poorly soluble layers were formed on the surface layer of the pattern. This is because neither the specific phenolic compound nor the specific amine compound as used in the above example is assumed to be mixed in the photosensitive composition [R-171].

Comparative Example 3

2.0 g of polymer [T-1] introduced with an acid labile group and 40 mg of onium salt (triphenylsulfonium tripulate) as a photo-acid generator were dissolved. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a varnish-type photosensitive composition [R-172].

According to the same method and condition as in the above Example, the pattern was formed using the photosensitive composition [T-172].

The cross-sectional shape of the resulting pattern was observed using a scanning electron microscope to measure the width of the acid and the space as a measure of the resolution. As a result, the resolution was 0.40 mu m for an exposure dose of 40 mJ / cm 2. However, protruding poorly soluble layers were formed on the surface layer of the pattern. This is because neither the specific phenolic compound nor the specific amine compound as used in the above example is assumed to be mixed in the photosensitive composition [R-172].

Example 173

The following test was done to check the temperature dependence of the photosensitive composition of this invention.

(1) Preparation of the photosensitive composition which consists of a polymer, onium salt, and an amine compound into which the group unstable to an acid was introduced.

2.0 g of polymer [T-5] having an unstable group introduced into the acid, 40 mg of onium salt (triphenylsulfonium trifolate) as a photo-acid forming material, and 6.00 g of methylmethoxy propionate as an amine compound Dissolved in. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a varnish-type photosensitive composition [R-15].

(2) pattern formation

Each photosensitive composition (varnish) prepared as described above was spin coated with a 6-inch silicon wafer. According to the conditions shown in Table 8 below, the resulting wafers were heat-treated in advance on a hot plate to form a 1.0 μm thick photosensitive composition film (resist film). The pattern was then exposed to the resist film using a KrF excimer laser stepper and the resulting wafers were heat treated on a hot plate according to the conditions shown in Table 8 below. Thereafter, each of the heat treated wafers was immersed in 1.59% aqueous tetramethylammonium hydroxide solution (TMAH aqueous solution) for 20 seconds to develop a resist film. The resulting wafers were then washed and dried to give a pattern consisting of lines and spaces.

The scanning electron microscope was used to observe the cross-sectional shape of the generated patterns, respectively, and the width of the line and space was measured as a measure of the resolution. Table 8 below shows the exposure (sensitivity) and resolution of the photosensitive compositions obtained under different temperature conditions.

Example 174

The following test was done to check the standing time dependence of the optical composition of this invention.

(1) Preparation of the photosensitive composition which consists of a polymer, onium salt, and an amine compound in which a group unstable to an acid is introduced.

2.0 g of polymer [T-5] having an unstable group introduced into the acid, 40 mg of onium salt (triphenylsulfonium trifolate) as a photo-acid forming material, and 6.00 g of methylmethoxy propionate as an amine compound Dissolved in. The resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a varnish photosensitive composition [R-15].

(2) pattern formation

The photosensitive composition (varnish) prepared as described above was spin coated with a 6-inch silicon wafer. The resulting wafers were pre-heated at a hot plate for 90 seconds at 95 ° C. to form a 1.0 μm thick photosensitive composition film (resist film). The pattern was then exposed to the resist film using a KrF excimer laser stepper. As shown in FIG. 4, the wafer was left standing at the interface between the excimer stepper, the resist film coater, and the developer for 0 to up to 120 minutes and heat-treated on a hot plate at 95 ° C. for 90 seconds. The heat treated wafers were then developed for 20 seconds in 1.59% aqueous tetramethylammonium hydroxide solution (TMAH solution). The resulting wafers were then washed and dried to give a pattern consisting of lines and spaces.

The cross-sectional shape of each generated pattern was observed using a scanning electron microscope, and the width of the line and the space was measured as a measurement of the shape figure. 4 shows the change in width in line and space for each settling time.

As described in detail above, according to the present invention, particularly with a light source having a short wavelength, it has a high photosensitivity and a high resolution, does not cause phase separation on the film, and is not easily affected by the surrounding environment, thereby reducing the rectangular cross section. A photosensitive composition is provided in which a micro pattern having a stable shape can be formed stably. The photosensitive composition and the formation of a resist film pattern using the photosensitive composition can have a surprising effect on photolithography in the method of manufacturing a semiconductor device, and therefore, the industrial value is very high.

Claims (10)

Polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer having a phenol skeleton with a group that is unstable with respect to an acid; At least one compound selected from the group consisting of an imidazole compound, an alanine compound, an adenine compound, an adenosine compound, and a quaternary ammonium salt compound, which increases the miscibility in the compound (b) and the resist film which generate an acid upon irradiation with light (c), wherein the content of component (a) is 5-80% by weight relative to the total solids content of the composition, and the content of component (b) and component (c) are each 0.01-50% by weight. Polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer having a phenol skeleton with a group that is unstable with respect to an acid; Compound (b) which generates an acid upon irradiation with light; And a phenol compound (d), wherein the content of component (a) is 5-80% by weight relative to the total solids content of the composition, and the content of component (b) and component (d) is each 0.01-50% by weight. Photosensitive composition. Polymer (a) obtained by protecting an alkali-soluble group of an alkali-soluble polymer having a phenol skeleton with a group that is unstable with respect to an acid; Compound (b) which generates an acid upon irradiation with light; At least one amine compound (c), which increases miscibility in the resist film and is selected from the group consisting of imidazole compounds, alanine compounds, adenine compounds, adenosine compounds, and quaternary ammonium salt compounds; And a phenol compound (d), wherein the content of component (a) is 10-60% by weight relative to the total solids content of the composition, the content of component (b) is 0.1-10% by weight, and the content of component (c) The photosensitive composition which is 5-50 weight% of silver. The composition of claim 2 wherein said phenolic compound is at least one compound selected from the group consisting of triphenol compounds and polyvinylphenols. 4. The composition of claim 3, wherein said phenolic compound is at least one compound selected from the group consisting of triphenolic compounds and polyvinylphenols. Forming a resin layer containing the photosensitive composition of claim 1 on a substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat-treated resin layer using one of an organic solvent and an alkali solution as a developing solution. Forming a resin layer containing the photosensitive composition of claim 2 on a substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat-treated resin layer using one of an organic solvent and an alkali solution as a developing solution. Forming a resin layer containing the photosensitive composition of claim 3 on a substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat-treated resin layer using one of an organic solvent and an alkali solution as a developing solution. Forming a resin layer containing the photosensitive composition of claim 4 on the substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat-treated resin layer using one of an organic solvent and an alkali solution as a developing solution. Forming a resin layer containing the photosensitive composition of claim 5 on a substrate; Exposing a pattern on the resin layer; Heat-treating the exposed resin layer; And developing the heat-treated resin layer using one of an organic solvent and an alkali solution as a developing solution.