JPH0572738A - Chemical amplification type resist and resist pattern forming method - Google Patents

Abstract

PURPOSE:To improve the adhesion to a substrate by using a copolymer contg. specific methacrylate having a neutral polar group as the polymer of the resist. CONSTITUTION:The copolymer contg. 1 to 30mol% methacrylate expressed by formula I and consisting of any one of tertbutyl methacrylate, 1',1'-dimethyl benzyl, tetrahydropyranyl methacrylate, and tert-butoxycarbonyoxy styrene is used as the monomer suitable for molding of the chemical amplification type resist having an OH group in the structure. In the formula I, R denotes 2 to 4C alkyl group having one OH group. The chemical amplification type resist consisting of the polymer composed of such copolymer and an acid generating agent which generates an acid by exposing is applied on the substrate to be treated and is subjected to alkaline development after selective exposing. The adhesion to the substrate to be processed is improved in this way without impairing resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified resist having improved adhesion. The integration of semiconductor integrated circuits has advanced and LSI and VLSI have been put into practical use, but this was realized by miniaturization of conductor lines and electrodes. Currently, the minimum pattern width is less than 1 μm (submicron). Have been put to practical use.

At first, ultraviolet rays were used as an exposure light source for forming a fine resist pattern. However, due to the limitation of wavelength, the light also shifts to a short wavelength and far ultraviolet rays are used for exposure. There is.

However, when such a deep ultraviolet ray is used for exposure, a conventional resist mainly composed of novolac resin has strong absorption in a short wavelength region. Therefore, the resolution is poor and it is difficult to use in the short wavelength region.

Therefore, commercialization of resists having excellent sensitivity and resolution at such wavelengths has been promoted.

[0005]

2. Description of the Related Art Instead of a conventional novolak resin-based resist, an acid generator (Phot) that generates an acid upon exposure is used as a method for realizing high sensitivity and high resolution of the resist.
o A method using Acid Generator (abbreviation PAG) has been proposed. (Japanese Patent Application No. 2-27660) In this method, a photoacid generator is mixed with a polymer having a functional group whose polarity is changed by an acid catalyst, and light irradiation is performed. The acid acts on the polymer as a catalyst in the post-baking (heat treatment) step performed after exposure to change the functional group to cause elimination reactions in a chain and change the polarity.

Therefore, alkali development becomes possible and high resolution can be realized, and this type of resist is called a chemically amplified resist. This type of resist needs only to include a functional group that changes depending on the acid catalyst, and therefore, a material having a small absorption at a short wavelength can be selected.

Further, since it is an amplification type that regenerates an acid when the functional group changes, it is expected to have high sensitivity. Here
Examples of the acid generator include triarylsulfonium salts such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium hexafluoroarsenate, and diaryl iodonium salts such as diphenyliodonium hexafluoroantimonate and diphenyliodonium hexafluoroarsenate. , Benzoin tosylate, sulfonates such as phenyl p-toluenesulfonate, halides such as hexachlorobenzene, 2,4-bis (trichloromethyl) -6- (p-methoxyphenyl) -1,3,5-triazine , And so on.

However, when a resist pattern is formed using such a chemically sensitized resist, a pattern without swelling can be obtained, and a fine pattern can be resolved due to poor adhesion to the substrate to be processed. Was difficult.

For example, tert-butyl methacrylate, 1 ', 1'-dimethylbenzyl methacrylate, 4-tert-butoxycarbonyloxystyrene and the like are known as polymers for chemically amplified resists, but all of them are treated. Due to its poor adhesion to the substrate, sub-micron patterns could not be resolved with good reproducibility.

[0010]

The chemically sensitized resist can realize a resist having a small absorption in the wavelength region of far ultraviolet light, and since it can be developed with an alkali, it does not swell and can form a fine pattern. ..

However, the chemically sensitized resist having the conventionally known composition has poor adhesion to the substrate to be processed, and therefore, it is not possible to resolve submicron patterns with good reproducibility. Yes, this solution is a challenge.

[0012]

[Means for Solving the Problems] The above-mentioned problems in a chemically amplified resist comprising a polymer having a functional group whose polarity is changed by an acid catalyst and an acid generator that generates an acid upon exposure are as follows. Containing 1 to 30 mol% of the methacrylic acid ester represented by the general formula, and any one of tert-butyl methacrylate, 1 ', 1'-dimethylbenzyl methacrylate, tetrahydropyranyl methacrylate, tert-butoxycarbonyloxystyrene This can be solved by constructing a chemically amplified resist, which is characterized by using a copolymer consisting of

[0013]

[Chemical 2]

[0014]

The inventors of the present invention have studied the method of improving the adhesion of the chemically sensitized resist to the substrate to be treated, and as a result, the monomer and the neutral compound of the organic compound, which has been conventionally known as a chemically amplified polymer for resist, The problem could be solved by using a copolymer with a monomer having a polar group, that is, a hydroxyl group (-OH).

That is, it was found that if the resist contains an OH group, the adhesion to the substrate is improved. Therefore,
As the monomer having an OH group in the structure and suitable for forming a chemically amplified resist, a methacrylic acid ester represented by the above general formula (1), for example, 2'-hydroxyethyl methacrylate is used.

Here, R in the general formula has 2 carbons (C).
~ 4 represents an alkyl group containing one OH group. The reason for limiting the content of the methacrylic acid ester represented by the above general formula (1) constituting the copolymer to 1 to 30 mol% is that as the content increases, it reacts with the acid generated from the photo-acid generator. This is because the amount of functional groups to be used is insufficient, the change in polarity becomes insufficient, and the resolution is impaired.

According to the present invention, by using a copolymer with a monomer having a neutral polar group as the polymer constituting the chemically amplified resist, the adhesion with the substrate to be treated can be achieved without impairing the resolution. It improves the sex.

[0018]

【Example】

Synthesis Example 1: (tert-butyl methacrylate-methacrylic acid
2'-Hydroxyethyl copolymer) Put a magnetic stirrer bar in a 100 ml eggplant-shaped flask, and add tert-butyl methacrylate ... 10.0 g (70.3 mmol) methacrylic acid. 2'-Hydroxyethyl ・ ・ ・ 915mg (7m mol) Azobisisobutyronitrile (AIBN) ・ ・ ・ ・ ・ 508mg (3.1m mol, 4mol%) Toluene ・ ・ ・ Add 15.5ml and dry N ₂ The mixture was kept at 75 ° C. in the atmosphere and stirred.

After 5 hours, heating and stirring were stopped, and the reaction solution was dropped into 4 liters of hexane while stirring to precipitate the solution. Then, the precipitate was separated by the sedimentation method and filtered through a glass filter, and the obtained polymer was mixed at 40 ° C. and 0.1 mm Hg for 6 minutes.
It was dried under reduced pressure for an hour.

The dried polymer was dissolved in 10 ml of tetrahydrofuran and then precipitated again with 2 liters of hexane, and the precipitate was separated by a precipitation method and filtered through a glass filter. It was dried under reduced pressure for 16 hours under the condition of Hg.

The yield was 8.5 g (yield 78%), the average molecular weight was 34,000 and the dispersity was 1.56, and the composition ratio of the copolymer was tert-butyl methacrylate: 2'-hydroxyethyl methacrylate = 88: It was 12.

Synthesis Example 2: (1 ', 1'-Dimethylbenzyl-methacrylic acid 2'-hydroxyethyl methacrylate copolymer) A 100 ml eggplant-shaped flask was equipped with a magnetic stirrer bar. 1 ', 1'-Dimethylbenzyl ・ ・ ・ 20.0g (89.8m mol) 2'-Hydroxyethyl methacrylate ・ ・ ・ 1.16g (9m mol) Azobisisobutyronitrile (AIBN) ・ ・ ・ 324mg (2.0 mmol, 2 mol%) Toluene (19.8 ml) was added, and the mixture was stirred at 75 ° C. in a dry N ₂ atmosphere.

After 5 hours, the heating and stirring were stopped, and the reaction solution was added dropwise to 4 liters of methanol with stirring to cause precipitation. Then, the precipitate was separated by the sedimentation method and filtered through a glass filter, and the obtained polymer was mixed at 40 ° C. and 0.1 mm Hg for 6 minutes.
It was dried under reduced pressure for an hour.

The dried polymer was dissolved in 15 ml of tetrahydrofuran and then precipitated again with 3 liters of methanol. The precipitate was separated by a precipitation method and filtered through a glass filter. The obtained polymer was 40 ° C. and 0.1 mm. It was dried under reduced pressure for 16 hours under the condition of Hg.

The yield is 18.5 g (yield 87%), average weight molecular weight
72000, dispersity is 1.73, the composition ratio of the copolymer is 1 ', 1'-methacrylic acid 2'-dimethylbenzyl-methacrylic acid 2'
-Droxyethyl = 90:10.

Synthesis Example 3: (Tetrahydropyranyl Methacrylate-2'-Hydroxyethyl Methacrylate Copolymer) A 100 ml eggplant-shaped flask was charged with a magnetic stirrer bar, and tetrahydropyranyl methacrylate ..・ ・ ・ ・ 10.0g (58.8m mol) 2'-Hydroxyethyl methacrylate ・ ・ ・ 770 mg (5.9m mol) Azobisisobutyronitrile (AIBN) ・ ・ ・ 212mg (1.3m mol, 2mol%) ) Toluene (26 ml) was added, and the mixture was stirred at 75 ° C in a dry N ₂ atmosphere.

After 5 hours, the heating and stirring were stopped, and the reaction solution was dropped into 4 liters of methanol while stirring to precipitate the solution. Then, the precipitate was separated by the sedimentation method and filtered through a glass filter, and the obtained polymer was mixed at 40 ° C. and 0.1 mm Hg for 6 minutes.
It was dried under reduced pressure for an hour.

The dried polymer was dissolved in 20 ml of tetrahydrofuran and then precipitated again with 3 liters of methanol, and the precipitate was separated by a precipitation method and filtered through a glass filter. The polymer obtained was 40 ° C. and 0.1 mm. It was dried under reduced pressure for 16 hours under the condition of Hg.

The yield was 9.5 g (yield 88%), the average weight molecular weight was 54,000, the dispersity was 1.66, and the composition ratio of the copolymer was tetrahydropyranyl methacrylate: methacrylic acid 2 '.
-Hydroxyethyl copolymer = 90:10.

Synthesis Example 4: (4-tert-: Butylcarbonyloxystyrene-2'-hydroxyethyl methacrylate copolymer) A 100 ml eggplant-shaped flask was equipped with a magnetic stirrer bar, in which 4-tert -: Butylcarbonyloxystyrene ・ ・ ・ 20.0g (90.8m mol) 2'-Hydroxyethyl methacrylate ・ ・ ・ 1.18g (9.1m mol) Azobisisobutyronitrile (AIBN) ・ ・ ・ ・ ・ 324mg (2m Toluene (20 ml) was added, and the mixture was stirred at 75 ° C. in a dry N ₂ atmosphere.

After 5 hours, heating and stirring were stopped, and the reaction solution was dropped into 4 liters of methanol while stirring to precipitate the solution. Then, the precipitate was separated by a precipitation method, filtered through a glass filter, and the obtained polymer was dried under reduced pressure at 30 ° C. and 0.1 mm Hg for 6 hours.

The dried polymer was dissolved in 15 ml of tetrahydrofuran and then precipitated again with 3 liters of methanol, and the precipitate was separated by a precipitation method and filtered through a glass filter. It was dried under reduced pressure for 16 hours under the condition of Hg.

The yield was 17 g (80% yield), the average weight molecular weight was 74,000, and the dispersity was 1.73. Example 1 1% by weight of benzointosylate as a photoacid generator was added to the copolymer synthesized in Synthesis Example 1 to prepare an ethyl lactate solution, which was used as a resist.

This resist solution was spin-coated on a hexamethyldisilazane (HMDS) -treated Si substrate, and then 100
Prebaking was performed at 20 ° C. for 20 minutes to form a chemically amplified resist film having a thickness of 1.0 μm.

Next, after exposing using an electron beam exposure apparatus with an accelerating voltage of 20 KV, it was developed for 60 seconds using an aqueous 2.38% alkali solution of tetramethylalmonium hydroxide (TMAH).

As a result, the sensitivity was 2.3 μC / cm ² , and
We were able to resolve a 6 μm line-and-space pattern. In addition, this resist is not treated with HMDS.
Even when it was applied to an oxide film substrate and a similar experiment was performed, peeling did not occur, and similar results could be obtained.

Example 2 1% by weight of triphenylsulfonium hexafluoroantimonate as a photoacid generator was added to the copolymer synthesized in Synthesis Example 2 to prepare an ethyl lactate solution, which was used as a resist.

This resist solution was spin-coated on a hexamethyldisilazane (HMDS) treated Si substrate, and then 100
Prebaking was performed at 20 ° C. for 20 minutes to form a chemically amplified resist film having a thickness of 1.0 μm.

Next, after exposing using an electron beam exposure apparatus with an accelerating voltage of 20 KV, it was developed for 60 seconds using a 2.38% alkaline aqueous solution of tetramethylammonium hydroxide (TMAH).

As a result, the sensitivity was 3.5 μC / cm ² , and
We were able to resolve a line-and-space pattern of 8 μm. In addition, this resist is not treated with HMDS.
Even when it was applied to an oxide film substrate and a similar experiment was performed, peeling did not occur, and similar results could be obtained.

Example 3 5% by weight of benzointosylate as a photoacid generator was added to the copolymer synthesized in Synthesis Example 3 to prepare a methyl cellosolve acetate (MCA) solution, which was used as a resist.

This resist solution was spin-coated on a HMDS-treated Si substrate and then prebaked at 100 ° C. for 20 minutes to form a chemically amplified resist film having a thickness of 1.0 μm. Next, using a KrF excimer laser stepper, open angle (NA)
Exposure at 0.37, bake at 100 ° C for 60 seconds, then
Development was performed for 60 seconds using an AH aqueous solution of 2.38%.

As a result, the sensitivity was 35 mJ / cm ² and 0.5
We were able to resolve μm line and space patterns. In addition, even if this resist was applied to a Si oxide film substrate not subjected to HMDS treatment and a similar experiment was performed, peeling did not occur, and similar results could be obtained.

Example 4: 1% by weight of benzoin tosylate as an acid generator based on the copolymer synthesized in Synthesis Example 4
In addition, an ethyl lactate solution was prepared and used as a resist.

The resist solution was spin-coated on a HMDS-treated Si substrate and then prebaked at 100 ° C. for 20 minutes to form a chemically amplified resist film having a thickness of 1.0 μm. Next, after exposure using an electron beam exposure device with an accelerating voltage of 20 KV, development was performed for 60 seconds using a 2.38% alkaline aqueous solution of TMAH.

As a result, the sensitivity was 2.3 μC / cm ² , and
We were able to resolve a 6 μm line-and-space pattern. In addition, this resist is not treated with HMDS.
Even when it was applied to an oxide film substrate and a similar experiment was performed, peeling did not occur, and similar results could be obtained.

[0047]

By using a copolymer containing a methacrylic acid ester having a neutral polar group as the polymer of the chemically amplified resist, the adhesiveness with the substrate is improved and the conventional HMDS treatment becomes unnecessary, Further, it became possible to form a fine pattern without impairing the resolution.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/028 9019-2H 7/038 505 7124-2H H01L 21/027

Claims (3)

[Claims] 1. A chemically amplified resist comprising a polymer having a functional group whose polarity is changed by an acid catalyst and an acid generator which generates an acid upon exposure, wherein a methacrylic acid ester represented by the following general formula is used. A chemically amplified resist characterized by using a copolymer containing 1 to 30 mol% as a polymer. [Chemical 1] 2. The copolymer with the methacrylic acid ester is tert-butyl methacrylate, 1 ′, 1′-methacrylic acid.
The chemically amplified resist according to claim 1, which is one of dimethylbenzyl, tetrahydropyranyl methacrylate, and 4-tert-butoxycarbonyloxystyrene. 3. A chemically amplified resist comprising a polymer comprising the copolymer according to claim 1 and an acid generator that generates an acid upon exposure is coated on a substrate to be processed, and after selective exposure. A method for forming a resist pattern, which comprises performing alkali development.