JP2000330284A - Resist material and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chemical amplification type resist material having both high resolution and high sensitivity and useful for forming a fine interconnection pattern in the production of a semiconductor device. SOLUTION: The resist material contains an acid sensitive polymer having a structural unit containing an alkali-soluble group protected by a protective group which is released by an acid to make the polymer alkali-soluble and a photo-acid generating agent which generates the acid when exposed. The photo-acid generating agent contains the diphenylamine salt, triphenylamine salt, cyclohexylamine salt or dicyclohexylamine salt of a specified sulfonic acid as a buffer compound in combination with the agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist material, and more particularly, to a chemical compound useful for forming a fine pattern in the manufacture of a semiconductor device such as a semiconductor integrated circuit while achieving both high resolution and high sensitivity. The present invention relates to an amplification type resist material. The present invention also relates to a method for forming a resist pattern using such a novel resist material.

[0002]

2. Description of the Related Art In recent years, integration of semiconductor integrated circuits has progressed, and LSIs and VLSIs have been put into practical use.
The minimum pattern of an integrated circuit extends to the submicron region and tends to be further miniaturized. Actually, the capacity is 1GB, 4G
B, 16 GB ... and the wiring width is 0.18
μm, 0.15 μm, 0.12 μm... Improving throughput is also urgently needed to reduce costs. Therefore, a resist for forming fine wiring is required to satisfy both high resolution and high sensitivity.

In order to satisfy such demands, for example, I
Ito et al. Of BM Co., Ltd. reported that a chemical amplification comprising an acid-sensitive resin capable of rendering the resin alkali-soluble by removing a protecting group of a protected alkali-soluble group with an acid, and a photoacid generator generating an acid upon exposure. Type resist (Tokuhei 2)
-27660). Chemically-amplified resists have already been put to practical use because they can simultaneously and easily achieve high resolution and high sensitivity. In the chemically amplified resist, a small amount of acid is generated from the photoacid generator by light irradiation during exposure, and is generated first by subsequently applying heat to the exposed resist film (post-exposure bake, PEB). The chain reaction of the resin proceeds through the catalytic action of the acid,
High sensitivity is achieved.

As an exposure source for lithography for forming a resist pattern, g-rays (wavelength 43
6 nm) and i-ray (wavelength 365 nm) ultraviolet light have been used, but with the miniaturization of patterns, far ultraviolet light, vacuum ultraviolet light, excimer laser, electron beam (E
B), X-rays and the like are used as light sources. Excimer lasers are two types, a KrF laser having a wavelength of 248 nm and an ArF laser having a wavelength of 193 nm, and are expected to be effective for forming fine patterns. Also,
The electron beam is regarded as important because it can draw various patterns arbitrarily by the program control of the electron beam exposure apparatus and is more flexible than other radiations.

An electron beam is suitable for forming a fine pattern because it can be focused on an extremely narrow beam of 0.01 μm or less, and therefore, application to mass production is also being studied. In order to respond to mass production from the lithography side, an electron beam is passed through a patterned aperture, the electron beam is formed into a desired pattern shape and batch exposure is performed, or a large number of electron beams that can be blanked independently are simultaneously irradiated A method of performing exposure (multi-beam exposure) has been developed. In view of these points, there is an urgent need to develop a high-performance electron beam resist.

[0006]

As described above, a resist for forming fine wiring is required to satisfy both high resolution and high sensitivity. However, the resolution of a chemically amplified resist greatly changes in consideration of sensitivity.
It is difficult to achieve both resolution and sensitivity, and it is even more difficult to increase them simultaneously. To increase the sensitivity of the resist,
It can be easily achieved by increasing the temperature of the post-exposure bake (PEB) to increase the amount of chain reaction,
As the temperature increases, the amount of diffusion of the acid increases, and as a result, the resolution decreases. Conversely, PEB
Although the resolution can be improved by lowering the temperature of, the sensitivity must be reduced.

[0007] There is also a method of adding a small amount of alkali to the resist to suppress the diffusion of acid and improve resolution.
In this case, the amount of the acid involved in the chain reaction is reduced, and the sensitivity must be reduced. In addition to the above-mentioned problems, the chemically amplified resist has a problem that it is sensitive to a trace amount of alkali impurities contained in the air, and its performance is easily changed during storage.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, that is, to use a specific ionizing radiation such as an excimer laser or an electron beam as an exposure source to achieve high resolution and high sensitivity. An object of the present invention is to provide a chemically amplified resist that can be achieved at the same time. Another object of the present invention is to provide an improved method for forming a resist pattern using such a chemically amplified resist.

The above and other objects of the present invention will be readily understood from the following detailed description.

[0010]

According to one aspect of the present invention, an alkali-soluble group protected by a protecting group has a structural unit capable of removing the protecting group by an acid to render the polymer alkali-soluble. In a chemically amplified resist material comprising an acid-sensitive polymer and a photoacid generator that generates an acid upon exposure, in combination with the photoacid generator, a diphenylamine salt of sulfonic acid, a triphenylamine salt,
A chemically amplified resist material comprising at least one organic ammonium salt selected from the group consisting of a cyclohexylamine salt and a dicyclohexylamine salt.

According to another aspect of the present invention, there is provided an acid-sensitive group having a structural unit, wherein an alkali-soluble group protected by a protecting group has a structural unit capable of removing the protecting group by an acid to render the polymer alkali-soluble. A polymer, a photoacid generator capable of generating an acid upon exposure, and at least one ammonium salt selected from the group consisting of diphenylamine salts, triphenylamine salts, cyclohexylamine salts and dicyclohexylamine salts of sulfonic acid. Applying a chemically amplified resist material containing on a substrate to be processed, selectively exposing the resist film on the substrate to be processed to ionizing radiation capable of causing generation of an acid from the photoacid generator, and After post-baking of the resist film after exposure, developing the latent image formed in the exposure step with an alkaline developer,
And a method for forming a resist pattern.

The term "ionizing radiation" used in the above-mentioned exposure step means, when used in the present specification, the above-mentioned specific ionizing radiation, excimer laser (KrF laser or ArF laser), It refers to a line, and possibly an ion beam.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a chemically amplified resist material according to the present invention, an alkali-soluble protecting group protected by a protecting group, which is used as a base resin thereof, is eliminated by an acid to make the polymer alkali-soluble. An acid-sensitive polymer having a structural unit that makes it possible for the polymer to have sensitivity to the specific ionizing radiation used, and to achieve both high resolution and high sensitivity in the resulting resist material. It is not particularly limited as long as it can be guaranteed and, if necessary, can also bring other desirable properties.

An acid-sensitive polymer which can be advantageously used as a base resin has, for example, an acidic group (for example, a hydroxyl group or a carboxyl group) in its molecule, and at least a part of the acidic group. Is replaced by a t-butoxycarbonyloxyl group (in the case of a hydroxyl group) or a t-butylcarboxyl group (in the case of a carboxyl group).

Phenol-novolak resin, cresol-novolak resin, phenol-cresol-novolak resin, polyhydroxystyrene, polycarboxystyrene and / or copolymers of hydroxystyrene with a monomer having a carbon-carbon double bond , A copolymer of carboxystyrene and a monomer having a carbon-carbon double bond, a copolymer of hydroxystyrene and carboxystyrene,
A silphenylene siloxane polymer having an acetylated benzene ring, a silphenylene siloxane polymer having a silanol group, a siloxane polymer having a carboxyl group or a hydroxyl group, and a silphenylene siloxane polymer having a carboxyl group or a hydroxyl group.

According to the findings of the present inventors, in the acid-sensitive polymer, a component containing a substituent which is decomposed by an acid, particularly a t-butoxycarbonyloxyl group, a t-butylcarboxyl group, etc. is decomposed by an acid. In addition, since the polarity greatly changes before and after decomposition, high contrast can be obtained. The acid-sensitive polymer or resin as described above may be used alone or in combination of two or more. Although the molecular weight of these polymers or resins can be varied in a wide range, it is usually about 1,000 to
It is in the range of 200,000.

The acid-sensitive polymer which can be used particularly advantageously as the base resin is a copolymer of para-hydroxystyrene and t-butyl methacrylate or a para-sensitive polymer, as used in the examples described below. It is a copolymer of hydroxystyrene and t-butoxycarbonyloxystyrene. Further, in addition to or instead of the acid-sensitive polymer described above, the acid-sensitive polymer which the present inventors have found useful is already known, for example, Japanese Patent Application Laid-Open No. The acid-sensitive polymer described in the specification of Japanese Patent Application No. 73173 or Japanese Patent Application No. 8-320105 may be used.

The photoacid generator used in combination with the acid-sensitive polymer as described above in the chemically amplified resist material of the present invention is a photoacid generator generally used in resist chemistry, That is, it can be a substance that generates a protonic acid upon irradiation with ionizing radiation such as an excimer laser or an electron beam. Suitable photoacid generators in the practice of the present invention include, but are not limited to, those listed below. (1) A diazonium salt represented by the following formula: Ar—N ₂ ⁺ X ⁻ (wherein, Ar represents a substituted or unsubstituted aromatic group such as a phenyl group, or an alicyclic group, and X is a halogen such as Cl, Br, I or F,
BF ₄ , BF ₆ , PF ₆ , AsF ₆ , SbF ₆ , CF ₃
SO ₃ , ClO ₄ or an organic sulfonic acid anion, etc.). (2) An iodonium salt represented by the following formula:

[0019]

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(In the above formula, Ar and X are the same as defined above.) (3) A sulfonium salt represented by the following formula:

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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(In the above formula, R, R ¹ , R ² , R ³ , Ar and X are each the same as defined above.
Is like a methyl group, R ^1, R ² and R ³ are a phenyl group, and tBu is a t- butyl group). (4) Sulfonate represented by the following formula:

[0028]

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(In the above formula, Ar and R are the same as defined above.) (5) An oxaazole derivative represented by the following formula:

[0030]

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(In the above formula, X is the same as defined above, provided that one of the —CX ₃ groups may be a substituted or unsubstituted aryl or alkenyl group). (6) An s-triazine derivative represented by the following formula:

[0032]

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(In the above formula, X is as defined above, provided that one of the —CX ₃ groups may be a substituted or unsubstituted aryl or alkenyl group). (7) a disulfone derivative represented by the _{formula: Ar-SO 2 -SO 2 -Ar} ( In the above formula, Ar are as defined above). (8) An imide compound represented by the following formula:

[0034]

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(Where X is as defined above). (9) In addition, for example, oxime sulfonate, diazonaphthoquinone, benzoin tosylate and the like. These photoacid generators are the following compounds, to give more specific examples. Diphenyl iodonium triflate:

[0036]

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Triphenylsulfonium triflate:

[0038]

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Triphenylsulfonium perfluorate:

[0040]

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Triphenylsulfonium hexafluoroantimonate:

[0042]

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Triphenylphosphonium hexafluorophosphate:

[0044]

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Diphenyl iodide hexafluorophosphate:

[0046]

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Benzoin tosylate:

[0048]

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In the chemically amplified resist material of the present invention, such a photoacid generator can be used in a wide range of addition amount depending on the type of exposure light source to be used and the desired acid release effect. However, the acid-sensitive polymer is usually used in an amount of about 1 to 30% by weight, preferably about 2 to 15% by weight, and more preferably about 3 to 7% by weight. Used in quantity.

In the chemically amplified resist material of the present invention, at least one photo-acid generator is used in combination with the above-described photo-acid generator.
Certain organic ammonium salts are used as buffer compounds. The organic ammonium salt is in an equilibrium state with the acid generated by the irradiation of ionizing radiation, and has an action of stabilizing a change in the acid concentration, that is, has a buffer action.
Thereby, in the case of the resist material of the present invention, a change in the acid concentration due to the diffusion of an acid or the intrusion of an alkali impurity can be suppressed, and the resolution can be improved. In addition, when an organic ammonium salt is added, a decrease in sensitivity can be avoided, unlike when only an alkali is simply added.

The present inventors have studied various organic ammonium salts used as buffer compounds. As a result, organic ammonium salts of sulfonic acid, especially, diphenylamine salt, triphenylamine salt, cyclohexylamine salt,
It has been found that dicyclohexylamine salt and the like can greatly improve the resist performance as compared with other organic ammonium salts.

The organic ammonium salts of sulfonic acids which can be advantageously used in the practice of the present invention are not limited to those listed below, but include diphenylamine salts of trifluorosulfonic acid and diphenylamine of perfluorosulfonic acid. Salts, triphenylamine salts of trifluorosulfonic acid, triphenylamine salts of perfluorosulfonic acid, cyclohexylamine salts of trifluorosulfonic acid, cyclohexylamine salts of perfluorosulfonic acid, dicyclohexylamine salts of trifluorosulfonic acid, and And dicyclohexylamine salt of perfluorosulfonic acid. These organic ammonium salts may be used alone or in combination of two or more.

In the chemically amplified resist material of the present invention, such an organic ammonium salt may be used in a wide range of addition amount depending on the kind and amount of the photoacid generator to be used and the desired buffer effect. Although you can do
Usually, the amount of the photoacid generator is preferably about 0.5% by weight or more, more preferably about 1% by weight of the photoacid generator.
It is an addition amount of not less than weight%. When the amount of the organic ammonium salt is less than 0.5% by weight, the effect of stabilizing the acid concentration is unlikely to be produced. In fact, when the amount of the organic ammonium salt is 0.2% by weight or less, almost no effect of the addition is observed. become unable.

The upper limit of the amount of the organic ammonium salt is not particularly limited. This is because the organic ammonium salt is neutral unlike an alkaline additive such as an amine, so that even a small amount thereof does not adversely affect the resist. However, when the added amount of the organic ammonium salt exceeds 200% by weight of the photoacid generator, the heat resistance of the entire resist is reduced, and the salt is deposited at the time of applying the resist, and the film cannot be formed. Will occur. Therefore, the amount of the organic ammonium salt to be added is preferably 150% by weight or less, more preferably 100% by weight or less of the photoacid generator.

According to the present invention, a chemically amplified resist material is prepared from the above-described acid-sensitive polymer, a photoacid generator, and an organic ammonium salt-based buffer compound. The preparation of such resists can be prepared in the form of a resist solution using techniques commonly practiced in resist chemistry. For example, the acid-sensitive polymer that constitutes the resist is prepared by polymerizing selected monomers to form the polymer in the presence of a suitable polymerization initiator, and then adding a photopolymer solution to the resulting polymer solution. A resist solution can be prepared by adding an acid generator and a buffer compound. In addition,
As described above, the “polymer” may be a homopolymer, or may be a two- or three-component copolymer. Here, the polymerization conditions and polymerization initiator used can be arbitrarily selected from a wide range of commonly used ones. For example, the following can be mentioned as an example of a suitable polymerization initiator. AIBN (azobisisobutyronitrile):

[0056]

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MAIB (dimethyl-2,2-azoisobisbutyrate):

[0058]

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In the preparation of such a resist solution,
The solvent used for dissolving the base resin and the like can be variously changed depending on the type of resist, coating conditions, and other factors. However, preferably, for example, ethyl lactate, propylene glycol monomethyl ether acetate (PGMEA), Organic solvents such as ethyl pyruvate and cyclohexanone. In particular, ethyl lactate, propylene glycol monomethyl ether acetate (PGM
When EA), ethyl pyruvate or the like is used, a resist pattern with higher contrast can be obtained.
It is also effective to add a surfactant to prevent striation after application of the resist solution. As a suitable surfactant, for example, KP manufactured by Shin-Etsu Chemical Co., Ltd.
-341 (trade name) and the like.

According to the present invention, the chemically amplified resist material of the present invention as described above is coated on a substrate to be processed, and the resist film on the substrate to be processed is caused to generate an acid from the photoacid generator. Selective exposure to possible ionizing radiation, and after post-baking of the exposed resist film, developing the latent image formed in the exposure step with an alkaline developer,
And a method for forming a resist pattern.

Although the method for forming a resist pattern according to the present invention can be carried out through any of various steps, it can preferably be carried out as follows. First, the solution of the chemically amplified resist prepared as described above is applied on the substrate to be processed. The substrate to be used here may be any substrate usually used in semiconductor devices and other devices, and specifically, a semiconductor substrate such as a silicon substrate, and various layers formed on the substrate. Films such as an oxide film, a polysilicon layer, a nitride film, and aluminum wiring can be used. These substrates may or may not have the circuitry already built. In some cases, these substrates are made of, for example, hexamethyldisilazane (HMDS) in order to improve the adhesion to the resist.
It is preferable to pre-treat with an adhesion promoter such as the above.

The application of the resist solution can be performed by using a conventional coating apparatus such as a spin coater, a dip coater, a roller coater and the like. Although the thickness of the formed resist film can be widely varied depending on factors such as the use of the resist film, it is usually about 0.3 to 2.
The range is 0 μm. Then, preferably, before selectively exposing the resist film formed in the above step to ionizing radiation, the resist film is heated to about 60 to 150 ° C., preferably about 6 to 150 ° C.
Prebake at a temperature of 0-100 ° C for about 60-180 seconds. For this pre-bake, for example, a heating means such as a hot plate can be used.

If a top coat film (protective film) is further applied on the resist film, for example,
A top coat film can be obtained by applying a solution of an olefin resin onto a resist film by spin coating and performing baking at a temperature of about 100 ° C. After formation and pre-baking of the resist film, the resist film is selectively exposed to radiation via a reticle by a conventional exposure apparatus. A suitable exposure apparatus is a commercially available electron beam exposure apparatus or an excimer stepper. As the exposure condition, an appropriate condition can be selected each time. For example, electron beam exposure
It can be carried out with an exposure in the range of about 0.1 to 100 μC / cm ² . As a result of this selective exposure, an acid is generated from the photoacid generator contained in the resist film, and finally a circuit pattern is printed on the resist film.

Then, the exposed resist film is immediately subjected to post-exposure bake (PEB), thereby causing an acid-catalyzed elimination reaction of the protective group. This post-exposure bake
This can be performed in the same manner as in the previous pre-bake. For example, the baking temperature is from about 60 to the decomposition temperature of the resist resin, preferably about 90 to 150C. In addition,
When a top coat film is used in combination, it is removed after the post-exposure bake and before the development, for example, with an organic solvent.

After the completion of the post-exposure bake, the exposed resist film is developed with an alkali developing solution according to a conventional method. As the alkali developer used here, an appropriate one can be arbitrarily selected from developers generally used in this technical field. Particularly preferred developers are ammonium compounds of the formula:

[0066]

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(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each
Which may be the same or different and represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms), a morpholine compound of the following formula:

[0068]

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Or a developer containing an aqueous solution or an alcohol solution of the mixture. Preferred examples of the ammonium compound as the developer are not limited to those listed below, but include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), and tetrapropylammonium hydroxide (TPAH). ), Tetrabutylammonium hydroxide (TBAH), and the like.

These developers are dissolved in water or dissolved in an alcohol such as methanol, ethanol, isopropyl alcohol or the like to form a developer. The concentration of soluble developer can vary widely, but generally ranges from about 0.1 to 15% by weight, preferably from about 0.1 to 10% by weight. Usually, a 2.38% by weight aqueous solution of TMAH is used as a developer. Although the development time is not particularly limited, it is generally in the range of about 1 to 5 minutes, preferably in the range of about 1 to 3 minutes. As a result of development, the exposed area of the resist film is dissolved and removed, and a desired resist pattern can be obtained. Finally, the obtained resist pattern is also rinsed with pure water according to a conventional method, and dried.

[0071]

EXAMPLES The present invention will now be described with reference to examples, but it should be understood that the present invention is not limited by these examples. The abbreviations used in the following description refer to the following compounds, respectively. Photoacid generator: Abbreviated symbol Compound name DPITF Diphenyliodonium triflate TPSTF Triphenylsulfonium triflate TPSPF Triphenylsulfonium perfluorate Organic ammonium salt: Abbreviated symbol Compound name DFA Diphenylamine salt of trifluorosulfonic acid TFA trifluorosulfonic acid Of CHA dicyclohexylamine salt of trifluorosulfonic acid CHA cyclohexylamine salt of trifluorosulfonic acid Example 1 1 g of parahydroxystyrene / t-butyl methacrylate copolymer (composition ratio 50:50, Mw = 12,000)
0, Mw / Mn = 1.7) in 0.05 g of diphenyliodonium triflate (as photoacid generator) and 1 mg
Was dissolved in 5.5 g of ethyl lactate together with the diphenylamine salt of trifluorosulfonic acid (as a buffer compound). The obtained resist solution was spin-coated on a silicon substrate pretreated with HMDS, and prebaked on a hot plate at 120 ° C. for 2 minutes. A resist film having a thickness of 0.4 μm was obtained.

Next, the obtained resist film was exposed to a 0.2 μm-wide line at an accelerating voltage of 30 kV by an electron beam exposure apparatus. Immediately after the completion of the exposure, the resist film was post-baked (PEB) on a hot plate at 120 ° C. for 2 minutes.
Thereafter, the resist film was developed with a developing solution composed of a 2.38% by weight aqueous solution of tetramethylammonium hydroxide (TMAH), NMD-3 manufactured by Tokyo Ohka, for 60 seconds,
Rinse with pure water. A resist pattern corresponding to the line pattern of the electron beam used for exposure was obtained. When the resolution of the obtained resist pattern was evaluated from the absolute value (μm) of the difference between the top size and the bottom size when the size of the top portion of the resist pattern became 0.2 μm, it was 0.001. It was found to have extremely high resolution. The sensitivity of this resist is about 3
μC / cm ² , which confirmed that the sensitivity was high. The evaluation results are also shown in Table 1 below. Examples 2 to 12 The procedure described in Example 1 was repeated. In the case of this example, as summarized in Table 1 below, diphenyliodonium triflate (DP) used as a photoacid generator was used.
Instead of the combination of ITF) and the organic ammonium salt used as buffer compound, diphenylamine salt of trifluorosulfonic acid (DFA), another combination was used within the scope of the present invention. There is no change in the amounts of the photoacid generator and the buffer compound.

When the resolution of the obtained resist pattern was evaluated, the results as shown in Table 1 below were obtained. Further, the sensitivity of each resist used in this example was about 3 μC / cm ² , and it was also confirmed that the resist had high sensitivity. Comparative Example 1 to Comparative Example 3 The procedure described in Example 1 was repeated. In the case of this example, for comparison, as described in Table 1 below, an organic ammonium compound was used in combination with a photoacid generator. No salt was used.

When the resolution of the obtained resist pattern was evaluated, the results as shown in Table 1 below were obtained. It was also confirmed that the sensitivity of each resist used in this example was lower than those in Examples 1 to 12. Table 1 Example No. Photoacid generator organic ammonium salt resolution (μm) Example 1 DPITF DFA 0.001 Example 2 TPSTF DFA 0.001 Example 3 FPSPF DFA 0.006 Example 4 DPITF TFA 0.004 Example 5 TPSTF TFA 0.002 Example 6 FPSPF TFA 0.008 Example 7 DPITF DCHA 0.001 Example 8 TPSTF DCHA 0.001 Example 9 FPSPF DCHA 0.001 Example 10 DPITF CHA 0.002 Example 11 TPSTF CHA 0.007 Example 12 FPSPF CHA0 0.003 Comparative Example 1 DPITF-0.02 Comparative Example 2 TPSTF-0.018 Comparative Example 3 FPSPF-0.017 From the results described in Table 1 above, according to the present invention, the organic acid generator was treated with an organic ammonium salt. When salt is added as a buffer compound It can be seen that it is possible to obtain a remarkable effect in the resolution. The numerical value of the resolution (μm) means that the smaller the value, the closer the pattern is to a rectangle and the higher the resolution. Examples 13 to 24 The procedure described in Examples 1 to 12 was repeated. In this example, the same amount of the base resin was replaced with 1 g of parahydroxystyrene / t-butyl methacrylate copolymer. Parahydroxystyrene / t-butoxycarbonyloxystyrene copolymer (composition ratio 80:20, Mw = 11,
000, Mw / Mn = 2.1).

When the resolution of the obtained resist pattern was evaluated, the results as shown in Table 2 below were obtained. The sensitivity of each of the resists used in this example was about 4 μC / cm ² , confirming that the resist was highly sensitive. Comparative Examples 4 to 6 The procedures described in Examples 13 to 15 were repeated, but in the case of this example, for comparison, as described in Table 2 below, in combination with a photoacid generator. No organic ammonium salt was used.

When the resolution of the obtained resist pattern was evaluated, the results as shown in Table 2 below were obtained. It was also confirmed that the sensitivity of each resist used in this example was lower than those of Examples 13 to 24. Table 2 Example No. Photoacid generator organic ammonium salt resolution (μm) Example 13 DPITF DFA 0.003 Example 14 TPSTF DFA 0.002 Example 15 FPSPF DFA 0.003 Example 16 DPITF TFA 0.002 Example 17 TPSTF TFA 0.002 Example 18 FPSPF TFA 0.006 Example 19 DPITF DCHA 0.002 Example 20 TPSTF DCHA 0.003 Example 21 FPSPF DCHA 0.001 Example 22 DPITF CHA 0.003 Example 23 TPSTF CHA 0.004 Example 24 FPSPF CHA0 0.003 Comparative Example 4 DPITF-0.015 Comparative Example 5 TPSTF-0.015 Comparative Example 6 FPSPF-0.014 From the results shown in Table 2 above, according to the present invention, the organic acid generator was treated with an organic ammonium salt. Buffer salt When added as it can be seen that it is possible to obtain a remarkable effect in the resolution. The numerical value of the resolution (μm) means that the smaller the value, the closer the pattern is to a rectangle and the higher the resolution. Comparative Example 7 The procedure described in Example 1 was repeated. In the case of this example, two types of superacid esters represented by the following formulas were replaced with a succinic acid instead of DPITF as a photoacid generator for comparison. The imide was used in the same amount.

[0077]

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[0078]

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Regarding the organic ammonium salt, in addition to DFA used in Example 1, TFA, DCHA, CH
An experiment was also performed in which A was also used and no organic ammonium salt was added. When the resolution of the obtained resist pattern was evaluated, the resist performance was almost the same irrespective of the type of the added organic ammonium salt and regardless of whether or not the organic ammonium salt was added. This is considered to be because the photoacid generator used was not suitable for the electron beam resist because it was suitable for the photoprocess, and the resolution of the resist was reduced depending on the photoacid generator. This also means that the organic ammonium salt used as a buffer compound in the present invention controls fine diffusion of acid to improve resolution, and there is a resolution determining factor far exceeding that. It is explained that the effect is difficult to be obtained when performing. Comparative Example 8 The procedure described in Example 1 was repeated. In this example, for comparison, the same amount of acetal was used instead of 1 g of parahydroxystyrene / t-butyl methacrylate copolymer as a base resin for comparison. (Mw = 10,000, see the following formula) was used.

[0080]

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As for the organic ammonium salt, in addition to DFA used in Example 1, TFA, DCHA, CH
An experiment was also performed in which A was also used and no organic ammonium salt was added. When the resolution of the obtained resist pattern was evaluated, the resist performance was almost the same irrespective of the type of the added organic ammonium salt and regardless of whether or not the organic ammonium salt was added. It is considered that this is because the acetal block resin used as the base resin had a remarkable dark reaction in the electron beam exposure apparatus, which resulted in a decrease in the resolution of the resist.

[0082]

According to the present invention, high resolution and high sensitivity can be simultaneously satisfied by using the above-mentioned specific composition as a chemically amplified resist material. As a light source at this time, an excimer laser or an electron beam particularly useful for forming a fine pattern can be used.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Ima 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (Reference) 2H025 AA01 AA02 AB16 AC06 AC08 AD03 BE00 BG00 CC20 FA03 FA12 FA17 2H096 AA25 BA20 EA05 EA06 FA01 GA08 5F046 BA03 CA04 JA04 JA19 JA22 LA12 LA14 LA18

Claims (2)

[Claims] Claims: 1. An alkali-soluble group protected by a protecting group, an acid-sensitive polymer having a structural unit for removing the protecting group by an acid to render the polymer alkali-soluble, and generating an acid upon exposure to light. Wherein the photoacid generator is selected from the group consisting of a diphenylamine salt of sulfonic acid, a triphenylamine salt, a cyclohexylamine salt and a dicyclohexylamine salt in combination with the photoacid generator. A chemically amplified resist material comprising at least one organic ammonium salt. 2. An acid-soluble polymer having a structural unit which makes an alkali-soluble group protected by a protecting group, a protective group is eliminated by an acid to make the polymer alkali-soluble, and an acid is generated by exposure to light. Chemically amplified resist material comprising a possible photoacid generator and at least one organic ammonium salt selected from the group consisting of diphenylamine, triphenylamine, cyclohexylamine and dicyclohexylamine salts of sulfonic acid Is applied on a substrate to be processed, and the resist film on the substrate to be processed is selectively exposed to ionizing radiation capable of causing generation of an acid from the photoacid generator, and post-baking of the resist film after exposure. Developing the latent image formed in the exposing step with an alkali developing solution, Forming method.