JPH04171452A - Resist and minute resist pattern forming method using the resist - Google Patents

Abstract

PURPOSE:To obtain high sensitivity, high image dissecting performance and processing stability and eliminate defects at the time of etching by forming a resist of a copolymer composed of 80-60 mol% of a 2,2,3,3-tetrafluoropropyl metacrylate unit and 20-40 mol% of a metacrylic acid unit. CONSTITUTION:A resist is formed of a copolymer composed of 80-60 mol% of a 2,2,3,3-tetrafluoropropyl metcrylate unit and 20-40 mol% of a metacrylic acid unit. The copolymer composed of the specific ratio of 2,2,3,3- tetrafluoropropyl metacrylate unit and metacrylic acid unit is provided with high sensitivity, high image dissecting performance and high adhesion, and also formed into such a resist as to be capable of developing with isopropyl alcohol as a single solvent. In addition, the generation of defects at the time of etching can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resist particularly useful as a positive resist for high-energy beam lithography, and a method for forming a fine resist pattern using the resist.

[Prior technology] In the technical fields of masking and semiconductor manufacturing, resists that are sensitive to high-energy rays such as electron beams and has been incorporated into.

Among these resists, there have traditionally been two types of resists used for manufacturing photomasks using electron beam exposure equipment and manufacturing semiconductor elements by direct writing on semiconductor substrates.
．． 2.3.4.4.4-Hexafluorobutyl methacrylate-glycidyl methacrylate copolymer (Japanese Patent Publication No. 6
4-11936) and fluoroalkyl methacrylate-methacrylic acid copolymer (JP-A-58-106)
536) is known.

[Problems to be Solved by the Invention] However, the resist made of the 2.2.3.4.4.4-hexafluorobutyl methacrylate-glycidyl methacrylate copolymer does not have sufficient resolution;
In addition, sensitivity changes due to various conditions during development, such as changes in the component ratio of the developer caused by the use of a mixed solvent in the developer. The problem is that it is difficult to replace.

On the other hand, the resist described in JP-A-51i-106536 is composed of a copolymer of fluoroalkyl methacrylate and methacrylic acid represented by the general formula,
Such copolymers are characterized by good sensitivity, resolution, and adhesion to substrates. However, in recent years, resists for photomask manufacturing have been in demand, and they have high sensitivity that responds to low irradiation doses of 2 μC/cm2 or less, and resolution that allows formation of patterns of 0.5 μm or less.
The above-mentioned resist materials cannot necessarily satisfy these higher demands.

Additionally, in the past, a mixed solvent in which two or more types of solvents were blended to adjust the solubility was used as a developer. In recent years, there has been a demand for improved process stability by using a single-solvent developer.

Furthermore, during an etching process when manufacturing a photomask or the like using a resist pattern, the etching solution may not penetrate into the intended pattern area, resulting in a defect called etching failure. As patterns become finer and more precise, defects during etching are brought into focus, and it is important to eliminate these defects. Regarding these recent demands, examples 2, 2.3.4.4.4-
When we investigated resists made of hexafluorobutyl methacrylate-1-methacrylic acid copolymer and 2.2.3.3-tetrafluoro-1゜l-dimethylpropyl methacrylate-methacrylic acid copolymer, we found that While maintaining the high sensitivity, high resolution, and high adhesion that these have,
It has been found that it is difficult to enable development with a single solvent, and furthermore, it is not possible to deal with defects during etching, which have become a focus of attention due to recent miniaturization.

Regarding defects during etching, see Japanese Patent Application Laid-Open No. 58-1065.
2, 2.3.4.4.4 described in Publication No. 36
While studying -hexafluorobutyl methacrylate-methacrylic acid copolymers, we discovered that the defects are correlated with the degree of hydrophilization of the resist film surface, and also with the presence or absence of scum after development. Based on this knowledge, when we increased the proportion of methacrylic acid units to increase hydrophilicity, the sensitivity and resolution decreased as the methacrylic acid units increased, and the solubility of the resist film itself increased, making it difficult to use a single solvent. Development becomes difficult, and even under possible development conditions, the remaining film rate of the resist film and the remaining film rate of the formed pattern decrease.
The original characteristic of high resolution has been lost.

Therefore, the present inventors aimed to create a resist that has high sensitivity, high resolution, and process stability, and does not cause defects during etching. As a result of overlapping the fluoroalkyl methacrylate-methacrylic acid copolymer, especially 2.2.3.3
The present inventors have discovered that a copolymer of -tetrafluoropropyl methacrylate and methacrylic acid in a specific ratio forms a resist that satisfies all of these requirements, and has completed the present invention.

[Means for Solving the Problems] That is, the present invention provides a resist comprising a copolymer comprising 80 to 60 mol% of 2.2.3.3-tetrafluoropropyl methacrylate units and 20 to 40 mol% of methacrylic acid units; The present invention also relates to the formability of a fine resist pattern, which is characterized by forming a film on a substrate using the resist, irradiating it with high-energy rays, and developing it with isopropyl alcohol.

[Function and Examples] The copolymer of the present invention consisting of a specific ratio of 2, 2, 3, 3-tetrafluoropropyl methacrylate units and methacrylic acid units has high sensitivity, high resolution, and high adhesion. and further provides a resist that can be developed using isopropyl alcohol as the sole solvent. Moreover,
The defects mentioned above do not occur during etching.

In the resist of the present invention, sensitivity and resolution do not decrease even if the proportion of methacrylic acid units in the copolymer used is increased. This fact is contrary to the above-mentioned findings obtained from 2,2.3.4.4.4-hexafluorobutyl methacrylate-methacrylic acid copolymer, etc.
This exceeded expectations based on conventional technology.

In addition, in a resist made of a copolymer of 2.2.3.3-tetrafluoropropyl methacrylate and methacrylic acid, the proportion of methacrylic acid units in the copolymer is 20%.
It was found that when the content was increased to 40 mol %, it became possible to significantly improve the wettability of the resist film surface, and the surface became hydrophilic. In this case, it has been found that the contact angle of the resist film with water before etching is 50 degrees or less, and that defects during etching hardly occur even in fine patterns. Furthermore, it was surprisingly found that when the proportion of methacrylic acid units was within the above range, no scum was generated after development. In this way, when the proportion of methacrylic acid units is 20 to 40 mol %, the problem of defects during etching can be solved even in fine patterns. Furthermore, since the ease with which the etching liquid enters the pattern is stabilized and does not change depending on the width of the pattern, uniform etching becomes possible, and as a result, pattern dimensional accuracy can be improved.

As described above, the proportion of methacrylic acid units in the copolymer used in the present invention is 20 to 40 mol%, and within this range, sensitivity and developability do not decrease, adhesion is sufficient, and a single solvent can be used. It can be developed with Moreover, as mentioned above, no defects occur during etching. If the proportion of methacrylic acid units is less than 20 mol %, it is difficult to obtain sufficient adhesion, and the solubility of the resist film decreases, making it extremely difficult to obtain good developing conditions. Furthermore, the wettability of the resist film surface decreases, scum occurs after development due to poor dissolution of the resist, and defects due to poor etching during etching increase. On the other hand, when the proportion of methacrylic acid units exceeds 40 mol%, sensitivity, resolution, and good hydrophilicity of the resist film can be maintained, but the solubility of the resist film increases, resulting in non-irradiation with high-energy rays. This is undesirable because the remaining film rate of the pattern and the formed pattern decreases, and the polymer component is eluted from the formed pattern and remains as a scum after development.

In addition, the molecular weight of the copolymer is 3 in methyl ethyl ketone.
Intrinsic viscosity measured at 5℃ [0.2 to 2.0 dll in η
A range of H is preferred. The intrinsic viscosity [η] is (1,2dl
If it is less than /g, the solubility of the resist film is too high and the residual film ratio of the resist film after development is greatly reduced, making it difficult to use. [If η exceeds 2.0 dl/g, the filtration performance of the filter for purifying the resist solution will deteriorate and the resist solution preparation process will be hindered.
Undesirable.

The copolymer used in the present invention can be produced by bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization of a mixture of 2.2.3.3-tetrafluoropropyl methacrylate and methacrylic acid in the presence of a conventional polymerization catalyst. Uro can be obtained by copolymerizing with various polymerization methods such as. The degree of polymerization can be adjusted by changing the amount of the polymerization catalyst, the amount of chain transfer agent added, the polymerization temperature, etc.

Further, as a method of forming a resist film of the copolymer on the substrate, a method of forming a resist film using a conventional method can be used. That is, the copolymer is dissolved in an aliphatic ketone, an aliphatic ester, an aliphatic alcohol, an aliphatic ether, an aromatic hydrocarbon, an alicyclic ketone, a halogenated hydrocarbon, or a mixture thereof to prepare a resist solution. A resist film is formed by coating the resist solution on various substrates using a spin coater or the like, and then performing a heat treatment such as a prebaking treatment to completely evaporate the solvent. The concentration of the solution is preferably 3 to 30% by weight, and the viscosity is preferably 5 to 10 Qcps.

In order to remove dust and the like, it is preferable to filter the film with a filter having an average pore size of 0.5 μm, for example, before coating. The heat treatment is preferably carried out at 140 to 240°C for 15 to 60 minutes. The thickness of the resist film formed is usually 0.2 to 20 μm. The substrate used is not particularly limited, and various substrates such as a chrome mask substrate, silicon, silicon nitride, and aluminum can be applied to the present invention.

Next, a fine resist pattern is formed by irradiating the resist film with high-energy rays to draw a pattern, and then developing it using a developer.

As the high-energy beam used for pattern drawing, electron beams, X-rays, ultraviolet rays of 30 θ nm or less, etc. can be used. For example, when using an electron beam, 0.5 to 2.
Irradiation is carried out appropriately at an irradiation dose of Ou, C/cm2 and an accelerating voltage of 10 to 3 GkV.

The developing solution is a solvent in which, in the resist film made of the copolymer, the solubility of the part whose molecular weight has been reduced by irradiation with high-energy rays and the original high-molecular-weight part which has not been irradiated with high-energy rays is significantly different. is used.

The present invention is characterized in that the developer is a single solvent, and the most suitable developer is isopropyl alcohol. Development conditions such as temperature and time may be determined as appropriate depending on the molecular weight of the copolymer, the composition of the copolymer, and the like.

After development, a rinsing process is performed using a solvent whose solubility is inferior to that of the developer. Examples of solvents for this purpose include alcohols such as normal propyl alcohol, isobutyl alcohol, and normal butyl alcohol, aliphatic hydrocarbons such as normal hexane and normal heptane, and alicyclic hydrocarbons such as cyclohexane and ethylcyclohexane. Finally, a desired fine resist pattern is formed by drying and baking.

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 85 parts of 2,2.3.3-tetrafluoropropyl methacrylate (parts by weight, the same applies hereinafter), 15 parts of methacrylic acid,
20 parts of tetrahydrofuran (hereinafter referred to as IF), 0.0 parts of azobisisobutyronitrile (hereinafter referred to as IBN).
0.04 parts of lauryl mercaptan and 0.06 parts of lauryl mercaptan were mixed to form a homogeneous solution, and after repeating freezing and degassing three times, this mixed solution was polymerized at 60° C. for 24 hours. Thereafter, the contents were taken out and dried under vacuum to obtain 94 parts of a copolymer.

The amount of methacrylic acid units in this copolymer was examined by titration, and it was confirmed that the copolymer contained 29 mol% of methacrylic acid units and was copolymerized in approximately the same amount as charged.

Further, the intrinsic viscosity [η] of this copolymer determined in methyl ethyl ketone at 35°C was 1.2 dl/g. The results are summarized in Table 1.

A uniform resist solution was prepared by adding 92 parts of methyl isobutyl ketone to 8 parts of this copolymer.

This solution was filtered through a PTFE membrane filter with a pore size of 0.5 μm, and the filtered resist solution was coated on a chrome mask substrate by spin coating.
Then, the solvent was baked at 200°C for 30 minutes to evaporate the solvent, and then cooled to room temperature to reduce the thickness.
A resist film with a thickness of 0.5 μm was formed.

Next, using an ERE-302 electron beam lithography system (manufactured by Elionix Co., Ltd.), line-and-space patterns of various intensities were drawn on the resist film with an electron beam at an acceleration voltage of 20 kV by varying the irradiation time. . 23 of these samples
Developed by immersing in isopropyl alcohol at ℃ for 7 minutes,
The resist pattern was then rinsed by immersion in isobutyl alcohol at 23° C. for 30 seconds to form a desired resist pattern, which was then observed using an optical microscope and an electron microscope.

As a result, the sensitivity was 1.6μC/Cm2, and the minimum resolution was 0.
The thickness was changed by 25 μm, and it was confirmed that no scum was formed. At that time, the remaining film rate in the non-irradiated area was 100%, confirming that there was no film loss. Next, the chrome mask substrate on which the resist pattern was formed was subjected to post-baking treatment at 80°C for 30 minutes, and then the DEM-
451 (manufactured by Nichiden Anelva), oxygen gas pressure 1
Descum processing was performed for 40 seconds under the condition of tarrSRF power of 100W. Then, 1 part of ceric ammonium nitrate
65g, perchloric acid 40ml and water 11g for 45 seconds at 23°C.
Then, it was washed with pure water for 60 seconds and dried with warm air. After drying, it was immersed in methyl isobutyl ketone for 60 seconds to dissolve and remove the resist film. After dissolving, add 30% to isopropyl alcohol.
The surface was washed by dipping for □ seconds, and the resist film was completely removed by drying with warm air.

Next, when the chrome mask substrate was observed using an optical microscope, it was found that the minimum resolution size was 0.25μω on the chrome mask.
The etching pattern was faithfully etched, making it possible to form a good mask with no etching solution seepage.

Furthermore, the − side is 0.25 μm, 0.5 μm Sl
, 4 square patterns (convex patterns) of 0 μm each.
Electron beam drawing was performed so that 000 pieces were formed, and development was performed under the same conditions as above to form a pattern. Next, the etched pattern formed on the chrome mask under the same conditions as above was observed using an optical microscope and an electron microscope. As a result of observation, the survival rate of the formed patterns of each size [(number of remaining patterns 7400) x 1
00] was determined, and the residual rate was 100% for all patterns, indicating high adhesion.

Furthermore, in order to examine the wettability of the resist film on the chrome mask substrate, a descum treatment before etching was performed under the same conditions as above, and the wettability of the surface immediately before being immersed in the etching solution was measured. As a result, the contact angle with water was 33 degrees.

Furthermore, the − side is 0.5 μm% 1.0 μm and 2.0 μm
Electron beam drawing was performed to form 400 m square patterns (concave patterns) each, and the pattern was formed by developing under the same conditions as above, and then the pattern was formed on a chrome mask under the same conditions as above. The etched material was observed using an optical microscope. As a result of the observation, the defect rate of each etched pattern (expressed as (7400 unetched patterns) x 100) was found to be 0% for both patterns, which is extremely high. It was confirmed that it has excellent etching properties. This is due to the excellent surface wettability of the resist film. The results are shown in Table 2.

Example 2 87 parts of 2,2.3.3-tetrafluoropropyl methacrylate, 13 parts of methacrylic acid, 20 parts of THF, ^I
Polymerization was carried out in the same manner as in Example 1 except that 104 parts of BNO and 0.1 part of lauryl mercaptan were used to obtain 93 parts of a copolymer. The composition and intrinsic viscosity [η] of the obtained copolymer are shown in Table 1.

Next, the prebaking conditions were adjusted using the obtained copolymer.
A resist film having a thickness of 0.5 μm was formed in the same manner as in Example 1 except that the temperature was 170° C. for 30 minutes, and a pattern was drawn and developed in the same manner as in Example 1. The results are shown in Table 2.

Etching was then carried out in the same manner as in Example 1, and it was confirmed that patterns with a minimum resolution size of 0.25 μm were faithfully etched.

In addition, the contact angle with respect to water and the defect rate of 0.5 μm, 1.0 μm and 2.0 μm patterns were investigated in the same manner as in Example 1. The results are shown in Table 2.

Example 3 90 parts of 2,2.3.3-tetrafluoropropyl methacrylate, 10 parts of methacrylic acid, 20 parts of THF, ^I
204 parts of BNO and lauryl mercaptan [1,1
Polymerization was carried out in the same manner as in Example 1 except that part was used.
94 parts of copolymer were obtained. The composition and intrinsic viscosity [η] of the obtained copolymer are shown in Table 1.

Next, the prebaking conditions were adjusted using the obtained copolymer.
A resist film having a thickness of 0.5 μm was formed in the same manner as in Example 1 except that the temperature was 170° C. for 30 minutes, and a pattern was drawn and developed in the same manner as in Example 1. The results are shown in Table 2.

Etching was then carried out in the same manner as in Example 1, and it was confirmed that patterns with a minimum resolution size of 0.25 μm were faithfully etched.

In addition, the contact angle with respect to water and the defect rate of 0.5 μm, 110 μm, and 2.0 μm patterns were investigated in the same manner as in Example 1. The results are shown in Table 2.

Example 4 90 parts of 2,2.3.3-tetrafluoropropyl methacrylate, 20 parts of methacrylic acid, 20 parts of THF, ^I
Polymerization was carried out in the same manner as in Example 1 except that 4 parts of BN00 and 0.06 parts of lauryl mercaptan were used to obtain 94 parts of a copolymer. Table 1 shows the composition and intrinsic viscosity [η] of the obtained copolymer.

Next, using the obtained copolymer, a resist film having a thickness of 0.5 μm was formed in the same manner as in Example 1, and a pattern was drawn and developed in the same manner as in Example 1. The result is the second
Shown in the table.

Etching was then carried out in the same manner as in Example 1, and it was confirmed that patterns with a minimum resolution size of 0.25 μm were faithfully etched.

In addition, the contact angle with respect to water and the defect rate of 0.5 μm, 1.0 μm and 2.0 μm patterns were investigated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1, except that 100 parts of 2,2.3.4.4.4-hexafluorobutyl methacrylate, 0.02 parts of ^IBN and 0.02 parts of lauryl mercaptan were used. 90 parts of copolymer were obtained. The composition and intrinsic viscosity [η] of the obtained copolymer are shown in Table 1.

Next, using the obtained copolymer, a resist film having a thickness of 0.5 μm was formed in the same manner as in Example 1, and a pattern was drawn and developed in the same manner as in Example 1. The results are shown in Table 2.

Then, when etching was carried out in the same manner as in Example 1, the etching solution did not penetrate into the inside of the pattern even for a pattern with a minimum resolution size of 2.0 .mu.m, and etching was impossible.

In addition, the contact angle with respect to water, 0.5 μm, 1. The defect rates of Qμm and 2.0μm patterns were investigated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2 90 parts of 2,2.3.4.4.4-hexafluorobutyl methacrylate, 1υ part of methacrylic acid, AIEND,
Polymerization was carried out in the same manner as in Example 1 except that 0.02 parts of copolymer 9 and 0.02 parts of lauryl mercaptan were used.
I got 2 copies. Composition and intrinsic viscosity of the obtained copolymer [η]
are shown in Table 1.

Next, using the obtained copolymer, a resist film having a thickness of 05 μm was formed in the same manner as in Example 1, and a pattern was drawn and developed in the same manner as in Example 1-. As a result, the resist film was completely dissolved and pattern formation was impossible. Furthermore, when processing was carried out under the same conditions as above except that the developer was replaced with isobutyl alcohol and the development time was 9 minutes, a minimum developed size of 0.5 μm was obtained, but the sensitivity was 3 and OμC/crn” was the limit. In addition, the remaining film rate in the non-irradiated area was 90%, indicating a decrease in film thickness.In particular, the remaining film rate in the formed pattern portion was 20% or less, making it unusable.

Furthermore, many scums were observed after development.

Then, when etching was performed in the same manner as in Example 1, the minimum resolution size was 0. Even with the EBzm pattern, the etching solution did not penetrate into the pattern, making it impossible to etch it.

In addition, the contact angle to water is 0.5 μm, 1.0 μm.
The defect rate of the 2.0 μm pattern was also investigated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3 Copolymer 90 was prepared in the same manner as in Example 1 except that 95 parts of 2,2.3.3-tetrafluoropropyl methacrylate, 5 parts of methacrylic acid, 0.02 part of AIBN and 0.02 part of lauryl mercaptan were used. I got a department. Table 1 shows the composition and intrinsic viscosity [η] of the obtained copolymer.

Next, using the obtained copolymer, a resist film with a thickness of 0.5 μm was formed in the same manner as in Example 1, a pattern was drawn in the same manner as in Example 1, and the film was immersed in isopropyl alcohol for 10 minutes. Other than that, development was carried out in the same manner as in Example 1. As a result, the sensitivity was 8 μC/CI1+2 or more. Furthermore, processing was carried out under the same conditions as above except that the development was changed to a methyl isobutyl ketone/isopropyl alcohol mixture (mixing ratio 9/91) and the development time was 2 minutes, but the resolution of 0.5 μm was Sensitivity: 2.0μC/c
It was found that +n2 was the limit and could not be used.

Further, the remaining film rate was 82%, and it was confirmed that the film was reduced.

In addition, the contact angle with respect to water was investigated in the same manner as in Example]. The results are shown in Table 2.

Comparative Example 4 99 parts of 2,2.3.3-tetrafluoro-1,1-dimethylpropyl methacrylate, 1 part of methacrylic acid, AI
02 parts of BNl and lauryl mercaptan C1,02
Polymerization was carried out in the same manner as in Example 1 except that part was used.
90 parts of copolymer were obtained. Table 1 shows the composition and intrinsic viscosity [η] of the obtained copentapolymer.

Next, using the obtained copolymer, a resist film with a thickness of 0.5 μm was formed in the same manner as in Example 1, a pattern was drawn in the same manner as in Example 1, and the film was immersed in isopropyl alcohol for 10 minutes. Other than that, development was carried out in the same manner as in Example 1. As a result, the sensitivity was 8 μC/cω2 or more. Furthermore, processing was carried out under the same conditions as above except that the developer was changed to an n-propertool/n-hexane mixture (mixing ratio 25/10) and the development time was 2 minutes. I couldn't image it. Also, the sensitivity is 1
It was confirmed that 0 μC/cm2 was the limit and could not be used.

Note that the contact angle with respect to water was examined in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 5 90 parts of 2,2.3.3-tetrafluoro-1,1-dimethylpropyl methacrylate, 10 parts of methacrylic acid, A
IBN [1,02 parts and lauryl mercaptan 0,0
Polymerization was carried out in the same manner as in Example 1 except that 2 parts of the copolymer was used, yielding 92 parts of a copolymer. Table 1 shows the composition and intrinsic viscosity [η] of the obtained copolymer.

Next, using the obtained copolymer, a resist film with a thickness of 0.5 μm was formed in the same manner as in Example 1, a pattern was drawn in the same manner as in Example J, and the resist film was immersed in isopropyl alcohol for 10 minutes. Other than that, development was carried out in the same manner as in Example 1. As a result, the sensitivity was 8 μC/cm2 or more. Furthermore, processing was carried out under the same conditions as above except that the developer was changed to a methyl isobutyl ketone/isopropyl alcohol mixture (mixing ratio 10/90) and the development time was 2 minutes, but a 0.5 μm pattern was resolved. I couldn't.

Further, it was found that the sensitivity was limited to 7.0 μC/cm 2 and was not usable.

Further, the remaining film rate was 90%, and it was confirmed that the film was reduced.

Note that the contact angle with respect to water was examined in the same manner as in Example 1. The results are shown in Table 2.

[See the margin below: Effects of the Invention] The resist of the present invention has high sensitivity, high resolution, and high adhesion, and has excellent process stability in that it can be developed with a single solvent, and is free from defects during etching. It is a resist that does not produce
This improves the productivity of photomasks and enables higher precision. Furthermore, by improving the hydrophilicity of the resist film surface, it is possible to eliminate defects during etching and improve dimensional stability, making photomask production even more efficient. becomes possible.

Patent applicant: Daikin Industries, Ltd.

Claims (1)

[Scope of Claims] 1. A resist comprising a copolymer comprising 80 to 60 mol% of 2,2,3,3-tetrafluoropropyl methacrylate units and 20 to 40 mol% of methacrylic acid units. 2. The resist according to claim 1, wherein the copolymer has an intrinsic viscosity of 0.2 to 2.0 dl/g as measured in methyl ethyl ketone at 35°C. 3. A method for forming a resist pattern, which comprises forming a film of the resist according to claim 1 on a substrate, irradiating the film with high-energy rays, and developing the film with isopropyl alcohol.