JPH1195436A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high throughput and excellent photosensitive stability and dimensional stability by including a process to bake a photosensitive layer, a process to expose the photosensitive layer to electron beams or ion beams according to a prescribed pattern, a process to develop the photosensitive layer after exposure, etc. SOLUTION: A photosensitive material described below is prepared. The photosensitive material has a photosensitive layer containing a polymer compd. the main chain of which is cut by irradiation of electron beams or ion beams, a compd. having substituents which decompose by acid catalytic reaction and produces polar groups, and a compd. which produces an acid by irradiation of chemical radiation of 150 to 450 nm wavelength, in one layer. The photosensitive layer is exposed to chemical radiation of 150 to 450 nm wavelength according to a prescribed pattern and then baked. Further, the photosensitive layer is irradiated with electron beams or ion beams according to the prescribed pattern. The photosensitive layer after exposed is developed to produce a fine pattern with a high throughput.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method used for fine processing in a manufacturing process of a semiconductor device or the like.

[0002]

2. Description of the Related Art Microfabrication technology using photolithography has been employed in the manufacturing process of electronic components such as LSIs. That is, first, a resist solution is applied on a substrate or the like to form a resist film, and then the obtained resist film is exposed by pattern light or beam scanning, and then developed with an alkali developing solution or the like. Process to form a resist pattern. Subsequently, the substrate or the like is etched using the resist pattern as a mask to form fine lines and openings, and finally, the resist is removed.

With the increase in integration, application of direct electron beam writing to mass production has been studied as a method of accurately forming a pattern of sub-quarter micron or less. However, there is a drawback that the throughput is lower than that of the batch exposure method. To overcome this, resists with high sensitivity to electron beams, particularly chemically sensitized resists, have been studied.

On the other hand, as a method for securing a throughput and forming a fine pattern from the exposure method, a rough pattern is exposed to a photoresist layer by mask exposure with ordinary light, and then the same layer is exposed to an electron beam. A method of drawing a fine pattern, and further performing development and etching has been proposed. Here, if a conventional chemically sensitized photoresist is used to increase the throughput, post-exposure baking (hereinafter referred to as PEB) is performed after light exposure and electron beam irradiation. When only PEB is performed, the elapsed time from the first exposure to the PEB becomes longer, and the sensitivity and dimensional stability of the first exposed portion are likely to be deteriorated. When the PEB is performed after the completion, the PEB is performed twice for the first exposed portion, and the dimensional stability is affected.

[0005]

As described above, when a conventional chemically amplified resist is to be exposed with both light and an electron beam, it is necessary to use a process method in order to maintain the sensitivity stability of each of the light exposure and the electron beam irradiation. It is impossible to do
It was susceptible to time fluctuations up to B. For this reason, there has been a demand for a pattern forming method which has a high throughput and is excellent in sensitivity stability and dimensional stability. The present invention has been made in view of the above, and has as its object to provide a pattern forming method which has a high throughput, and is excellent in sensitivity stability and dimensional stability.

[0006]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> The pattern forming method of the present invention is characterized by comprising the following steps. (1) a polymer compound whose main chain is broken by irradiation with an electron beam or an ion beam, a compound having a substituent which is decomposed by an acid-catalyzed reaction to produce a polar group, and
Preparing a photosensitive material having a photosensitive layer comprising a single layer of a compound capable of generating an acid upon irradiation with actinic radiation of 50 to 450 nm; (2) a wavelength of 150 to 450 n
exposing the photosensitive layer in a predetermined pattern with actinic radiation of m, (3) subsequently baking the photosensitive layer, and (4) further exposing the photosensitive layer to a predetermined pattern by an electron beam or an ion beam. And (5) developing the exposed photosensitive layer.

<Effect> According to the method of the present invention, a fine pattern can be manufactured with high throughput while maintaining sensitivity stability and dimensional stability.

[Specific description of the invention] <Photosensitive material> The photosensitive material used in the pattern forming method of the present invention has a photosensitive layer comprising the following components in a single layer. (A) a polymer compound whose main chain is broken by irradiation with an electron beam or an ion beam, (b) a compound having a substituent which is decomposed by an acid-catalyzed reaction to generate a polar group, and
(C) a compound that generates an acid upon irradiation with actinic radiation having a wavelength of 150 to 450 nm. Here, as the polymer compound (a) whose main chain is cut by irradiation with an electron beam or an ion beam, any suitable compound can be used. Examples of such a compound include a copolymer of a sulfone and an olefin derivative, a copolymer of an acrylate derivative having a halogen or a cyano group at the α-position and an olefin derivative, a copolymer containing methyl methacrylate,
And others. In addition, this polymer component
In order to increase the dissolution contrast at the time of development, it preferably has an alkali-soluble group.

Also, any compound can be used as the compound (b) having a substituent which is decomposed by an acid-catalyzed reaction to produce a polar group. As the substituent decomposed by the acid-catalyzed reaction, any group known in the art can be used. Specifically, (a) an ester group, for example, t-butyl ester, isopropyl ester, ethyl ester, methyl ester, and others, (b) an ether group, for example, t-butyl ether, (c) an acetal group, for example, tetrahydropyrani Ether, ethoxyethyl ether, tetrahydrofuranyl ether, ethyl vinyl ether, and (d) oxycarbonyl groups such as t-butoxycarbonyl (hereinafter, tB
oc), methoxycarbonyl, ethoxycarbonyl, and others, (e) alkylsilyl groups such as trimethylsilyl, (he) silylether groups such as trimethylsilylether, triethylsilylether, and others. Further, the skeleton compound of the compound having these substituents is also arbitrary, but usually, this is a compound to be blended as a resin component of the photosensitive composition, various copolymers, for example, a novolak resin, and other, Is mentioned.

The polymer compound (a) and the compound (b) may be independent compounds,
In the present invention, it is preferable to use a polymer compound having both functions (a) and (b). That is, the photosensitive material used in the pattern forming method of the present invention is:
It is preferable that the main chain is broken by irradiation with an electron beam or an ion beam, and the side chain contains a high molecular compound having a substituent which generates a polar group by being decomposed by an acid catalyst reaction. When a polymer compound having both functions (a) and (b) is used in the method of the present invention, no other polymer compound (a) or compound (b) is required. Among such compounds, preferred are those represented by the following general formula (I) or (II).

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Here, R ₁ is a divalent organic group having a substituent which is decomposed by an acid-catalyzed reaction to form a polar group. Specifically, R ₁ is decomposed by the acid-catalyzed reaction to form a polar group. Examples include an alkylene group or an arylene group having a generated substituent. R ₂ is an alkali-soluble group, for example, —OH, —COOH, —OC—CH ₂
It is a divalent organic group having —COOH, —CF ₂ OH, —C ₆ H ₄ OH, and others. Also, l, m and n
Is a number representing the molar ratio of each monomer component. On the other hand, in the general formula (II), OR ₃ is a substituent which is decomposed by an acid-catalyzed reaction to form a polar group, preferably a hydroxyl group, for example, the above-mentioned substituent. R ₄ is a substituted or unsubstituted aromatic group (for example, phenyl, naphthyl, and others) or a substituted or unsubstituted aliphatic group (for example, cyclohexyl, norbornyl, adamantyl, and others). X ₁ , X ₂ and X ₃
The monovalent substituent, for example -H, -CH _3, -CH ₂ C
H ₃ , —CN, or halogen, and at least one of X ₁ , X _2, and X ₃ is —CN or halogen. P, q and r are numbers representing the molar ratio of each monomer component.

The polymer compound (a), the compound (b), or the polymer compound having the functions of both (a) and (b) can be used in combination of two or more as necessary. .

As the compound (c) that generates an acid upon irradiation with actinic radiation having a wavelength of 150 to 450 nm, a photoacid generator generally used in the art can be used.
Specific examples of such compounds are as follows.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

Embedded image Here, x represents the mixing ratio of each monomer component,
It is any number from 0 to 1.

[0022]

Embedded image Here, x represents the mixing ratio of each monomer component,
It is any number from 0 to 1.

[0023]

Embedded image Here, Z is any substituent such as alkyl, alkoxy, aryl, halogen, etc., and X ⁺ -is any cationic group.

[0024]

Embedded image These photoacid generators, based on the weight of the polymer component contained in the photosensitive material used in the pattern forming method of the present invention,
0.1 to 30 parts by weight, preferably 0.3 to 15 parts by weight,
In an amount of If the amount of the photoacid generator is less than the above amount, sufficient sensitivity may not be obtained,
If the amount is larger than the above-mentioned amount, the light transmittance of the photoresist composition at the exposure wavelength may be impaired due to the light absorption of the photoacid generator itself.

The photosensitive material used in the pattern forming method of the present invention may further contain, as a dissolution inhibitor, a compound having a group which is decomposed by an acid-catalyzed reaction and shows alkali solubility. Examples of the group which is decomposed by the acid-catalyzed reaction and exhibits alkali solubility include the same protective groups as those described above for substituting R in the compound of the general formula (I). As the dissolution inhibitor used in this manner, any one known in the art can be used, and specific examples include the following.

[0026]

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[0027]

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[0028]

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[0029]

Embedded image Here, n is an arbitrary number representing the degree of polymerization.

[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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When the photosensitive composition of the present invention is used for a chemically amplified resist, it is necessary to prevent the chemically amplified resist from adsorbing a basic compound in the environment, thereby affecting the resist properties. A trace amount of a basic compound can be added to the composition. As such a basic compound, any compound can be used as long as the effects of the present invention are not impaired. Specifically, (a) pyridine derivatives, for example, t-butylpyridine, benzylpyridine, various pyridiniums Salts and other (ii) aniline derivatives such as methylaniline, N-ethylaniline, N, N-dimethylaniline, (c) amine compounds,
For example, diphenylamine, N-methyldiphenylamine, and others, (ho) indene derivatives, and others. The amount of these basic compounds to be added is generally 0.1 to 10% based on the number of moles of the photoacid generator.
It is 50 mol%, preferably 1 to 15 mol%. If the amount of the basic compound is less than this, the effect of adding the basic compound is less likely to be exhibited, and if the amount is too large, the sensitivity of the photosensitive composition may decrease.

The photosensitive composition of the present invention is prepared by generally dissolving each of the above-mentioned components in an organic solvent and, if necessary, filtering the solution with a membrane filter or the like.
As the organic solvent used here, those generally used in the art are used. Specifically, (a) ketone,
For example, cyclohexanone, acetone, ethyl methyl ketone, methyl isobutyl ketone, and others, (b) cellosolves such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, and others;
Esters such as ethyl acetate, butyl acetate, isoamyl acetate, γ-butyrolactone, methyl 3-methoxypropionate, and others. In addition, depending on the type of the photosensitive composition, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidinone, and others can be used to improve solubility. Further, a lactic acid ester such as ethyl lactate, propylene glycol monoethyl acetate, or the like can be used as the low toxicity solvent.

As the components of the photosensitive composition, the polymer compound (a), the compound (b), the polymer compound having both functions of (a) and (b), the photoacid generator (c) , A dissolution inhibitor, an organic solvent, and others can be used in combination of two or more as necessary.

In the pattern forming method of the present invention, a photosensitive material provided with a photosensitive layer by applying the above photosensitive composition on a substrate or the like is used. As the substrate on which the photosensitive composition is applied, any substrate known in the art can be used. Specific examples of such a substrate include a silicon wafer, a doped silicon wafer, a silicon wafer having various insulating films, electrodes, or wirings formed on its surface, a mask blank, and a III-V group such as GaAs or AlGaAs. Compound semiconductor wafers, and others. Chromium or chromium oxide deposited substrate, aluminum deposited substrate, IBSPG coated substrate, S
An OG coated substrate and a SiN coated substrate can also be used.

The method of applying the photosensitive composition to the substrate is also optional, and includes spin coating, dip coating,
Doctor blade methods, curtain coating, and other methods are used.

The applied photosensitive composition is usually at 170 ° C.
Thereafter, the photosensitive layer is dried by heating at preferably 70 to 120 ° C. to form a photosensitive layer.

<Pattern Forming Method> The pattern forming method of the present invention is based on a specific treatment using the above-mentioned photosensitive material.

That is, the pattern forming method of the present invention comprises the following steps. (1) a step of preparing the above-mentioned photosensitive material; (2) a wavelength of 1
Exposing the photosensitive layer in a predetermined pattern with actinic radiation of 50 to 450 nm, (3) subsequently baking the photosensitive layer, and (4) further exposing the photosensitive layer in a predetermined pattern by an electron beam or an ion beam. Irradiating, and (5) developing the exposed photosensitive layer.

First, the photosensitive material prepared as described above is imagewise exposed to light having a wavelength of 150 to 450 nm. The method of exposure may be a method of performing exposure through a predetermined mask pattern or a method of performing exposure by directly scanning the photosensitive layer with actinic radiation. The actinic radiation used for exposure has a wavelength of 150 to 450 nm, and any one can be used as long as it can release an acid from the photoacid generator (c).
Specifically, ultraviolet light, i-line, h-line, or g-line of a mercury lamp, xenon lamp light, deep UV light (for example, Kr
Excimer laser light such as F or ArF), and others.

Subsequently, a baking process is performed. The baking treatment can be performed by any method known in the art, but generally, heating on a hot plate or in a heating furnace,
Alternatively, it is performed by infrared irradiation or the like. This baking treatment is performed in order to promote an acid-catalyzed reaction in the chemically amplified resist composition, but heat treatment is usually performed at 150 ° C. or lower to suppress excessive diffusion of acid.

Further, a fine pattern is irradiated by an electron beam or an ion beam. As the exposure device, any device known in the art can be used,
Generally, an electron beam writing apparatus or an ion beam writing apparatus is used. Any type of electron beam writing apparatus can be used, and the beam format (for example, a circular beam, a fixed rectangular beam, a variable shaped beam and others) used for the electron beam writing apparatus, a beam scanning method (for example, a vector scanning method, a raster scanning method, and Other materials can be selected depending on the photosensitive material to be used and the purpose of use of the pattern.

Any type of ion beam device can be used. Various elements such as an element serving as an ion source, an ion extraction portion of the device, a beam converging device, a beam deflecting device, and others have been studied, and any suitable one can be used.

Subsequently, the photosensitive layer is developed with an alkaline developer. As the developer used, any one known in the art can be used. Specifically, (a)
Organic alkali aqueous solutions such as tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, choline aqueous solution and others, and (ii) inorganic alkali aqueous solutions such as potassium hydroxide aqueous solution, sodium hydroxide aqueous solution and others. The concentration of the alkali developing solution is not limited, but is 15 mol% in order to increase the dissolution rate difference between the exposed part and the unexposed part of the photosensitive layer, that is, to increase the dissolution contrast.
The following concentrations are preferred. In addition, by irradiation with an electron beam or an ion beam, the high molecular compound is cut in the main chain to reduce the molecular weight. However, since an organic solvent is suitable for developing a pattern using the same, the present invention The developer used in the pattern forming method preferably contains an organic solvent. Organic solvents that can be used include, for example, (a) alcohols such as methanol,
Isopropanol, butanol, and others (b)
Ketones, such as methyl isobutyl ketone, acetone, and others; (c) aromatic solvents, such as toluene, xylene, and others; (d) N-methylpyrrolidone, dimethyl sulfoxide, N, N-dimethylformamide;
And others. These alkaline aqueous solutions and organic solvents can be used in combination of any two or more kinds.

The mechanism of pattern formation according to the method of the present invention is considered as follows. First, 150
The photoacid generator (c) exposed to actinic radiation at ~ 450 nm releases the acid. The released acid is diffused by a subsequent baking treatment, and is decomposed by an acid-catalyzed reaction of the compound (b) to react with a substituent that becomes a polar group.
Compound (b) is made alkali-soluble. Further, the main chain of the polymer compound (a) is cut by being irradiated with an electron beam or an ion beam, so that the polymer compound (a) has a low molecular weight and the solubility in a developing solution is increased. The scission of the main chain of the polymer compound (a) by the electron beam or the ion beam is not due to the chemical amplification action, so that baking is unnecessary, and the aforementioned 150 to 450
Since the part exposed by the actinic radiation of nm is not affected, the pattern exposed by the actinic radiation of 150 to 450 nm and the electron beam or the ion beam is accurately reproduced.

The method for forming a pattern according to the present invention comprises the above-mentioned steps (1) to (5), but further steps may be added if necessary. For example, a step of forming a flattening layer before coating a photosensitive layer on a substrate, a step of forming an anti-reflection layer to reduce the reflection of exposure light, and washing the substrate after development with water or the like A rinsing step for removing a developer and the like, a step of irradiating ultraviolet rays again before dry etching, and the like can be combined with the above steps.

[0051]

EXAMPLE 1 5.8 g of the following copolymer (III) and triphenylsulfonium triflate (hereinafter TP) as an acid generator
0.04 g (referred to as S-OTf) was dissolved in 94 g of methoxymethyl propionate, followed by filtration using a 0.2 μm membrane filter to prepare a resist solution.

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The obtained resist solution was applied on a silicon wafer by spin coating, and heated at 100 ° C. for 90 seconds to form a resist layer having a thickness of 0.16 μm.

Next, a wavelength of 248 nm is applied to the surface of the resist layer.
A predetermined pattern light was exposed at an exposure amount of 20 mJ / cm ² using a stepper using KrF excimer laser light as a light source, followed by baking at 100 ° C. for 2 minutes. Further, a predetermined pattern light was exposed on the surface of the resist layer at an exposure amount of 5 μC / cm ² using an electron beam drawing apparatus of 3 keV.

The exposed resist is selectively dissolved and removed using a 1: 1 mixture of a 0.27N aqueous solution of tetrahydroammonium hydroxide (TMAH) and isopropyl alcohol to form a positive resist pattern. Formed. Here, the time (T _E ) from exposure with a KrF excimer laser beam to electron beam drawing is set to 10
The dimensional variations of the KrF excimer laser light exposure pattern (0.25 μmL & S) and the electron beam writing pattern (0.15 μmL & S) were examined for minutes, 1 hour, or 2 hours. The results obtained are shown in Table 1.

[0055]

Example 2 5.8 g of the following copolymer (IV) and 0.04 g of TPS-OTf as an acid generator were mixed with 94 g of cyclohexanone.
And filtered using a 0.2 μm membrane filter to prepare a resist solution.

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The obtained resist solution was applied on a silicon wafer by spin coating, and heated at 100 ° C. for 90 seconds to form a resist layer having a thickness of 0.16 μm.

Next, a wavelength of 248 nm is applied to the surface of the resist layer.
Using a KrF excimer laser light source as a light source, a predetermined pattern light was exposed at an exposure amount of 22 mJ / cm ² , followed by baking at 100 ° C. for 2 minutes by a line baker within 10 minutes. . Further, the surface of the resist layer was exposed to a predetermined pattern light at an exposure amount of 1 μC / cm ² using an electron beam drawing apparatus of 3 keV.

The exposed resist is subjected to 0.108N T
The exposed portion was selectively dissolved and removed using a 1: 1 mixed solution of MAH aqueous solution and isopropyl alcohol to form a positive resist pattern.

[0060] Here, 10 minutes T _E, 1 hour, or 2
With respect to time, the dimensional variations of the KrF excimer laser light exposure pattern (0.25 μmL & S) and the electron beam writing pattern (0.15 μmL & S) were examined. The results obtained are shown in Table 2.

[0061]

COMPARATIVE EXAMPLE 1 100 parts by weight of a polymer in which 30% of the hydroxyl groups of polyhydroxystyrene having a molecular weight of 12,000 were substituted with t-Boc, and 1 part by weight of an acid generator, TPS-OTf, were dissolved in PGMEA to form a resist. A solution was prepared. The obtained resist solution was applied on a silicon wafer by spin coating to form a resist layer having a thickness of 0.16 μm.

Next, a wavelength of 248 nm is applied to the surface of the resist layer.
Using a stepper with a KrF excimer laser beam as a light source, a predetermined pattern light is exposed at an exposure amount of 25 mJ / cm ² , and further, an exposure amount of 1 μC / cm is applied to the surface of the resist layer using a 3 keV electron beam drawing apparatus. ^{In step 2} , a predetermined pattern light was exposed. The exposed resist was baked at 100 ° C. for 2 minutes.

The resist was selectively dissolved and removed using a 0.21N aqueous TMAH solution to form a positive resist pattern.

[0065] Here, 10 minutes T _E, 1 hour, or 2
With respect to time, the dimensional variations of the KrF excimer laser light exposure pattern (0.25 μmL & S) and the electron beam writing pattern (0.15 μmL & S) were examined. The results obtained are shown in Table 3.

[0066]

Comparative Example 2 Instead of performing baking after electron beam writing, K
After exposure with rF excimer laser light, a positive resist pattern was formed in the same manner as in Comparative Example 1, except that baking was performed at 100 ° C. for 2 minutes using a line baker within 10 minutes. Examination of the dimensional variations when varying the T _E, the results obtained were as shown in Table 4.

[0068]

[0069]

According to the pattern forming method of the present invention, a fine pattern can be manufactured with high throughput while maintaining sensitivity stability and dimensional stability.

Claims (5)

[Claims] 1. A pattern forming method comprising the following steps. (1) a polymer compound whose main chain is broken by irradiation with an electron beam or an ion beam, a compound having a substituent which is decomposed by an acid-catalyzed reaction to produce a polar group, and
Preparing a photosensitive material having a photosensitive layer comprising a single layer of a compound capable of generating an acid upon irradiation with actinic radiation of 50 to 450 nm; (2) a wavelength of 150 to 450 n
exposing the photosensitive layer in a predetermined pattern with actinic radiation of m, (3) subsequently baking the photosensitive layer, and (4) further exposing the photosensitive layer to a predetermined pattern by an electron beam or an ion beam. And (5) developing the exposed photosensitive layer. 2. The pattern forming method according to claim 1, wherein the polymer compound whose main chain is cut by irradiation with an electron beam or an ion beam has an alkali-soluble group. 3. The method according to claim 1, wherein actinic radiation having a wavelength of 150 to 450 nm is K
The pattern forming method according to claim 1, wherein the pattern forming method is rF excimer laser light or ArF excimer laser light. 4. The polymer compound whose main chain is broken by irradiation with an electron beam or an ion beam is the same as a compound having a substituent which is decomposed by an acid-catalyzed reaction to produce a polar group. The pattern forming method according to any one of the above. 5. A polymer compound whose main chain is cut by irradiation with an electron beam or an ion beam is represented by the following general formula (I):
5. The pattern forming method according to claim 1, which is a compound of (II). Embedded image (Where R ₁ is a divalent organic group having a substituent that decomposes by an acid-catalyzed reaction to form a polar group, and R ₂ is
A divalent organic group having an alkali-soluble group,
And n are numbers representing the molar ratio of the respective monomer components, OR ₃ is a substituent which is decomposed by an acid-catalyzed reaction to form a polar group, and R ₄ is a substituted or unsubstituted aromatic An aliphatic group, or a substituted or unsubstituted aliphatic group,
X ₁ , X ₂ and X ₃ are monovalent substituents, at least one of X ₁ , X ₂ and X ₃ is —CN or halogen, and p, q and r are the respective monomers It is a number representing the molar ratio of the components. )