JPH1152562A - Photoresist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical amplification type positive type photoresist compsn. excellent in various performances such as sensitivity, resolution, heat resistance, the rate of a residual film, coating property, a profile and resistance to a time delay effect. SOLUTION: This positive type photoresist compsn. contains a resin which becomes alkali-soluble from an alkali-insoluble or slightly alkali-soluble resin by the action of an acid and a tetraarylborate compd. represented by the formula as an acid generating agent. In the formula, R1 -R20 are each independently H, F, trifluoromethyl or 1-4C alkyl, at least one of R1 -R20 is F or trifluoromethyl and R<+> is diarylhalonium or triarylsulfonium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist composition suitable for lithography used in the production of semiconductor integrated circuits, which acts by far ultraviolet rays (including excimer lasers, etc.), electron beams, X-rays or radiation. It is about.

[0002]

2. Description of the Related Art In recent years, with the increasing integration of integrated circuits, it has been required to form submicron patterns. In particular, excimer laser lithography is 64M DR
Attention has been given to enabling the manufacture of AM and 256M DRAM. As a resist suitable for such an excimer laser lithography process, a so-called chemically amplified resist utilizing an acid catalyst and a chemical amplification effect has been proposed. A chemically amplified resist changes the solubility of an irradiated part in an alkali developing solution by a reaction using an acid generated from an acid generator in a part irradiated with radiation, thereby providing a positive or negative type photo resist. A resist is obtained.

In a chemically amplified resist, an acid generated by irradiation with radiation is subjected to a post-exposure heat treatment.
ure bake: hereinafter, may be abbreviated as “PEB”), to remove protective groups such as resin, and to regenerate acid, thereby realizing high sensitivity.
Further higher sensitivity is desired, and improvement in resolution is also desired.

Further, the chemically amplified resist has a disadvantage that it is easily affected by the environment. In other words, the so-called time delay, whose performance changes greatly depending on the standing time from irradiation to PEB,
The effect occurs. Due to such a time delay effect, the resolution is lowered, and a film development phenomenon (T-shaping) occurs in the pattern after development, and the profile is deteriorated. It is considered that the cause of the time delay effect is that acids generated in the resist are deactivated by amines present in a trace amount in the environmental atmosphere.

[0005]

SUMMARY OF THE INVENTION The present invention relates to sensitivity, resolution, heat resistance, remaining film ratio, coating properties, profile, time
An object of the present invention is to provide a chemically amplified positive photoresist composition excellent in various properties such as delay effect resistance. The present inventors have conducted intensive studies to achieve such an object, and as a result, have found that a positive photoresist composition having excellent performance can be obtained by combining specific components, thereby completing the present invention. .

[0006]

That is, the present invention provides a resin which becomes alkali-soluble by the action of an acid from an insoluble or hardly soluble alkali, and a tetraaryl represented by the following formula (I) as an acid generator. An object of the present invention is to provide a positive photoresist composition containing a borate compound.

[0007]

Wherein R _{1 to} R ₂₀ are independently of each other hydrogen,
Represents fluorine, trifluoromethyl or alkyl having 1 to 4 carbon atoms, at least one of which is fluorine or trifluoromethyl, and R ⁺ represents diarylhalonium or triarylsulfonium.

The present invention has a great feature in that the tetraaryl borate compound represented by the above formula (I) is used as an acid generator for a photoresist.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A resin component, which is a main component of a photoresist composition, is insoluble or hardly soluble in alkali by itself, but undergoes a chemical change by the action of an acid to become alkali-soluble. . For example, a resin is used in which at least a part of the phenolic hydroxyl group of the alkali-soluble resin having a phenol skeleton is protected by an acid-labile group having the ability to inhibit dissolution in an alkali developer.

Examples of the base alkali-soluble resin include novolak resin, polyvinyl phenol resin, polyisopropenyl phenol resin, vinyl phenol and styrene, copolymer of acrylonitrile, methyl methacrylate or methyl acrylate, and isopropenyl phenol and styrene. , Acrylonitrile, methyl methacrylate or a copolymer with methyl acrylate. The positional relationship between the hydroxyl group and the vinyl group or the isopropenyl group in vinylphenol and isopropenylphenol is not particularly limited.
Vinyl phenol and p-isopropenyl phenol are preferred. These resins may be partially hydrogenated to improve transparency. In addition, an alkyl group, an alkoxy group, or the like may be introduced into the phenol nucleus of the resin as long as it is soluble in alkali.
Among these alkali-soluble resins, a polyvinylphenol-based resin, that is, a homopolymer of vinylphenol or a copolymer of vinylphenol and another monomer is preferably used.

Groups which are introduced into such an alkali-soluble resin and have the ability to inhibit dissolution in an alkali developing solution but are unstable to acids can be various protecting groups known in the art. For example, a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tetrahydro-2-pyranyl group, a tetrahydro-2-furyl group, a methoxymethyl group, a 1-ethoxyethyl group, and the like,
These groups will replace the hydrogens of the phenolic hydroxyl groups. Among these protecting groups, a 1-ethoxyethyl group is particularly preferred in the present invention. When these protecting groups are introduced into the phenolic hydroxyl groups of an alkali-soluble resin having a phenol skeleton, the proportion of the phenolic hydroxyl groups in the alkali-soluble resin that are substituted with a protecting group (protection group introduction rate) is generally Preferably it is in the range of 10 to 50%.

In particular, as the whole or a part of the resin component, the phenolic hydroxyl group of the above-mentioned polyvinylphenol-based resin has a dissolution inhibiting ability in an alkali developing solution and is partially unstable to an acid. It is preferable to use a resin protected by Among them, a resin in which a phenolic hydroxyl group of a polyvinylphenol resin is partially 1-ethoxyethyl etherified is preferred.

The acid generator constituting the photoresist composition is a compound which generates an acid by irradiating the substance itself or a resist composition containing the substance with radiation. In the present invention, a tetraaryl borate compound represented by the above formula (I) is used as at least a part of the acid generator. By including such a tetraaryl borate compound, a resist having particularly excellent balance of sensitivity, resolution and profile can be obtained.

In the formula (I), R _{1 to} R ₂₀ each independently represent hydrogen, fluorine, trifluoromethyl or
-4 alkyl, at least one of which must be fluorine or trifluoromethyl. When the carbon number of the alkyl is 3 or more, it may be linear or branched. R _{1 to} R ₂₀ are particularly preferably fluorine, in which case the tetraarylborate compound of the formula (I) is represented by the following formula (II).

[0016]

R ^{+ in} formulas (I) and (II) is diarylhalonium or triarylsulfonium;
Here, aryl means an aromatic residue, for example, unsubstituted or substituted phenyl. Examples of the group that can be substituted for phenyl include alkyl having about 1 to 20 carbons, cycloalkyl having 6 or less carbons, and 1 to 1 carbons.
Alkoxy of about 0 and the like can be mentioned. The two aryls constituting the diarylhalonium and the three aryls constituting the triarylsulfonium may be the same or different. Further, the halogen constituting the diarylhalonium can be chlorine, bromine, iodine, etc., and iodine is particularly advantageous. As the diarylhalonium represented by R ⁺ , more specifically, the following formula ( II
Those represented by I) are advantageous.

[0018]

Wherein R _{21 to} R ₃₀ independently of one another, hydrogen,
Represents alkyl having 1 to 20 carbons, cycloalkyl having 6 or less carbons, or alkoxy having 1 to 10 carbons. Here, when the alkyl and alkoxy have 3 or more carbon atoms, they may be linear or branched.

The tetraarylborate compound of the formula (I) is known, for example, from JP-A-6-184170, and specific examples thereof include the following.

Diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, (4-octyloxyphenyl) phenyliodonium tetrakis (pentafluorophenyl) borate, tolycumyliodonium tetrakis
(Pentafluorophenyl) borate, tolylcumyliodonium tetrakis (trifluoromethylphenyl)
Borate, tolylcumyliodonium tetrakis (difluorophenyl) borate, triphenylsulfonium tetrakis (pentafluorophenyl) borate and the like.

In the present invention, it is essential to use a tetraaryl borate compound of the formula (I) as at least a part of the acid generator, and the acid generator consists essentially of this tetraaryl borate compound. Alternatively, another acid generator may be contained together with the tetraaryl borate compound. When another acid generator is used in combination with the tetraaryl borate compound of the formula (I), the content of the tetraaryl borate compound is preferably 10% by weight or more based on the total amount of the acid generator.

The other acid generator used in combination with the tetraaryl borate compound of the formula (I) can be various compounds or mixtures known in the art which generate an acid upon irradiation, for example, a compound of the formula Onium salt compounds other than (I), organic halogen compounds, orthoquinonediazide compounds, diazomethane disulfonyl compounds, disulfone compounds, other sulfonic acid compounds, and the like.
Among them, in combination with the tetraarylborate compound of the formula (I), a diazomethanedisulfonyl compound is preferred. The diazomethane disulfonyl compound includes bis (cyclohexylsulfonyl) diazomethane, bis (phenylsulfonyl) diazomethane, bis (p-tolylsulfonyl) diazomethane, bis (2,4-xylylsulfonyl) diazomethane and the like.

The positive photoresist composition of the present invention comprises:
Although it contains the resin and the acid generator described above, it is preferable to further contain a nitrogen-containing compound in order to further improve the resistance to the time delay effect. As the nitrogen-containing compound used here, a tertiary amine is preferable. In particular, a compound which remains in the resist film even after pre-baking of the resist film formed on the substrate and exerts an effect, specifically under normal pressure Those having a boiling point of 150 ° C. or higher are preferred. Specific examples of such a tertiary amine include tributylamine, N, N-dimethylundecylamine, N, N-dimethyldodecylamine, tripentylamine, N-methyldioctylamine, N-methyldicyclohexylamine, and trihexyl. Examples include amine, triisooctylamine, and trioctylamine.

The preferred composition ratio of each component constituting the positive photoresist composition is such that the resin component is in the range of 75 to 99% by weight, and the acid generator is 0 based on the total solid weight in the composition. 0.05 to 20% by weight. When a nitrogen-containing compound is blended, the content is preferably in the range of 0.001 to 10% by weight based on the total solid weight in the composition. The positive photoresist composition of the present invention may further contain other components as necessary, for example, various additives commonly used in this field, such as a sensitizer, a dye, and an adhesion improver. Can also.

The positive photoresist composition is usually
A resist solution is prepared by dissolving each of the above components in a solvent so that the total solid content concentration is 10 to 50% by weight, and is applied onto a substrate such as a silicon wafer. The solvent used here may be any solvent that dissolves the respective components, has an appropriate drying rate, and gives a uniform and smooth coating film after the solvent is evaporated, and is commonly used in this field. be able to. For example, glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether and diethylene glycol dimethyl ether. Such as glycol mono or diethers, esters such as ethyl lactate, butyl acetate and ethyl pyruvate, ketones such as 2-heptanone, cyclohexanone and methyl isobutyl ketone, and aromatic hydrocarbons such as xylene. Can be These solvents can be used alone or in combination of two or more.

The resist film applied and dried on the substrate is subjected to an exposure treatment for patterning, and then to a heat treatment (PEB) for accelerating a deprotection group reaction, and then to an alkali developing solution. And a positive pattern is formed. The alkaline developer used here can be various alkaline aqueous solutions used in this field, but generally, an aqueous solution of tetramethylammonium hydroxide is often used.

[0028]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the part in an example represents a weight part unless there is particular description.

Reference Example (Protection of Resin) In a 500 ml four-necked flask purged with nitrogen, poly (p-vinylphenol) having a weight average molecular weight (Mw) of 23,900 and a polydispersity (Mw / Mn) of 1.12. [VP-1 manufactured by Nippon Soda Co., Ltd.
5000 "] 25 g (20 as p-vinylphenol unit
8 mmol) and 0.021 g of p-toluenesulfonic acid
(0.109 mmol) and 1,4-dioxane 25
Dissolved in 0 g. To this solution, 7.88 g (109 mmol) of ethyl vinyl ether was added dropwise, followed by reaction at 25 ° C. for 5 hours. This reaction solution was mixed with 150 parts of
The mixture was added dropwise to 0 ml and then filtered to obtain a white wet cake. This wet cake is reconstituted with 1,4-dioxane 2
The solution was added dropwise to 1500 ml of ion-exchanged water and filtered. The obtained wet cake was washed by stirring in 600 g of ion-exchanged water, filtered to take out the wet cake, and this washing operation with ion-exchanged water was repeated twice. The obtained white wet cake was dried under reduced pressure to obtain a resin in which hydroxyl groups of poly (p-vinylphenol) were partially 1-ethoxyethyl etherified. When this resin was analyzed by ¹ H-NMR, 35% of the hydroxyl groups were protected by 1-ethoxyethyl groups. This resin has a weight average molecular weight of 31,200 and a polydispersity of 1.17.
Met.

Example 1 13.5 parts of the resin synthesized in Reference Example, (p-
Tolyl) (p-cumyl) iodonium tetrakis (pentafluorophenyl) borate (“PHOTOINITIATOR 2074” manufactured by Rhone Poulin Co.) and 0.5 part of N-methyldioctylamine as a nitrogen-containing compound, and propylene glycol It was dissolved in 70 parts of monomethyl ether acetate. This solution was filtered through a fluororesin filter having a pore size of 0.1 μm to prepare a resist solution.

The above-mentioned resist solution was applied to a silicon wafer that had been cleaned by a conventional method using a spin coater so that the film thickness after drying was 0.72 μm. Next, this silicon wafer was prebaked on a hot plate at 90 ° C. for 90 seconds. The coating film after pre-baking was exposed through a chrome mask having a pattern using a KrF excimer laser stepper (“NSR-1755 EX8A” manufactured by Nikon Corporation, NA = 0.45) having an exposure wavelength of 248 nm. Exposure treatment was performed by changing the amount stepwise. Immediately after exposure, the wafer was heated on a hot plate at 100 ° C. for 90 seconds to
B, and a deprotection group reaction of the exposed part was performed. This was developed with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide to obtain a positive pattern. When the formed pattern was observed with an electron microscope, it was found to be 18 mJ / cm.
^At a light exposure of ² , a fine pattern of 0.24 μm was resolved with a good profile.

Example 2 13.5 parts of the resin synthesized in the reference example, (p-
0.1 part of tolyl) (p-cumyl) iodonium tetrakis (pentafluorophenyl) borate, 0.5 part of bis (cyclohexylsulfonyl) diazomethane as an acid generator, and 0.02 part of N-methyldioctylamine as a nitrogen-containing compound Was dissolved in 70 parts of propylene glycol monomethyl ether acetate. This solution was filtered through a fluororesin filter having a pore size of 0.1 μm to prepare a resist solution. The same operation as in Example 1 was performed using this resist solution, and the formed pattern was observed with an electron microscope. As a result, a fine pattern of 0.24 μm was resolved with a good profile at an exposure dose of 38 mJ / cm ² . .

The resist compositions of Examples 1 and 2 showed exactly the same sensitivity and resolution when left for 30 minutes after exposure and then subjected to PEB. The profile was also good.

Comparative Example 1 13.5 parts of the resin synthesized in the Reference Example, 0.5 parts of diphenyliodonium tetrafluoroborate [“DPI-101” manufactured by Midori Kagaku Co., Ltd.] as an acid generator, and as a nitrogen-containing compound 0.04 parts of N-methyldioctylamine were dissolved in 70 parts of propylene glycol monomethyl ether acetate. This solution was filtered through a fluororesin filter having a pore size of 0.1 μm to prepare a resist solution. The same operation as in Example 1 was performed using this resist solution, and the formed pattern was observed with an electron microscope. As a result, only a pattern up to 0.28 μm was resolved at an exposure dose of 16 mJ / cm ² . Even when the exposure amount was increased, the resolution did not become smaller than 0.28 μm. When the exposure amount was increased, the profile worsened.

Comparative Example 2 Comparative Example 1 was repeated except that the acid generator was changed to 0.5 parts of di (4-tert-butylphenyl) iodonium tetrafluoroborate [“BBI-101” manufactured by Midori Kagaku Co., Ltd.]. The same operation as described above was performed. Observation of the formed pattern with an electron microscope revealed that only a pattern up to 0.26 μm was resolved at an exposure dose of 32 mJ / cm ² .

Comparative Example 3 Di (4-tert-butylphenyl) iodonium triflate [BBI-10 manufactured by Midori Kagaku Co., Ltd.] was used as an acid generator.
5 "] The same operation as in Comparative Example 1 was carried out except that the part was changed to 0.5 part. The formed pattern was observed with an electron microscope, and a pattern of 0.25 μm was exposed at an exposure of 26 mJ / cm ^2. Despite resolution, the film loss was very large and the profile was poor.

[0037]

According to the present invention, a photoresist composition containing a tetraaryl borate compound of the formula (I) as an acid generator is hardly affected by the environment, and has a deep ultraviolet (including excimer laser) light source. It shows high sensitivity, excellent resolution, and excellent profile in the exposure area of high energy radiation such as electron beam, X-ray and emitted light. Therefore, a fine photoresist pattern can be formed with high accuracy by using this photoresist composition.

Claims (11)

[Claims] 1. A resin which becomes alkali-soluble by the action of an acid from a state of being insoluble or hardly soluble in alkali, and the following formula (I) (Wherein, R _{1 to} R ₂₀ independently represent hydrogen, fluorine, trifluoromethyl or alkyl having 1 to 4 carbon atoms, at least one of which is fluorine or trifluoromethyl, and R ⁺ is A positive photoresist composition comprising an acid generator containing a tetraaryl borate compound represented by diarylhalonium or triarylsulfonium). 2. The composition according to claim 1, wherein R _{1 to} R ₂₀ in the formula (I) are all fluorine. 3. A compound represented by the following formula (III) wherein R ⁺ in the formula (I) is (Wherein, R _{21 to} R ₃₀ are each independently hydrogen, carbon number 1 to
The diaryl iodonium represented by 20 alkyl, cycloalkyl having 6 or less carbon atoms, or alkoxy having 1 to 10 carbon atoms). 4. The composition according to claim 1, wherein the acid generator consists essentially of a tetraaryl borate compound of the formula (I). 5. The method according to claim 1, wherein the acid generator contains another acid generator together with the tetraaryl borate compound of the formula (I).
A composition according to any one of claims 1 to 3. 6. The composition according to claim 5, wherein the other acid generator is a diazomethane disulfonyl compound. 7. A resin which becomes alkali-soluble by the action of an acid from a state of being insoluble or hardly soluble in an alkali, has the ability to inhibit the dissolution of a phenolic hydroxyl group of a polyvinylphenol-based resin in an alkali developing solution. The composition according to any one of claims 1 to 6, comprising a resin partially protected by an acid-labile group. 8. The composition according to claim 7, wherein the phenolic hydroxyl group of the polyvinylphenol resin is partially 1-ethoxyethyl etherified. 9. A resin which becomes alkali-soluble by the action of an acid from an insoluble or hardly soluble state with respect to an alkali, based on the total solid content of the composition, and 75 to 99% by weight of an acid generator. The composition according to any one of claims 1 to 8, comprising 0.05 to 20% by weight. 10. The composition according to claim 1, further comprising a nitrogen-containing compound. 11. A resin which becomes alkali-soluble by the action of an acid from an insoluble or hardly soluble state in an alkali, from 75 to 99% by weight, and an acid generator in an amount of from 0.1 to 100% by weight based on the total solid weight in the composition. 0.05 to 20% by weight, and the nitrogen-containing compound is 0.0
The composition according to claim 10, which contains 1 to 10% by weight.