JPH05265212A - Resist material and pattern forming using it - Google Patents

Abstract

PURPOSE:To provide excellent transparency to far ultraviolet rays and sufficient etching resistance by constituting a resist material of a copolymer of acrylic ester or alpha substituted acrylic ester and specified tetrahydropyranyl ester. CONSTITUTION:A resist material is composed of a copolymer of acrylic ester having an adamantine skeleton at an ester portion or alpha substituted acrylic ester and tetrahydropyranyl ester of acrylic acid or alpha substituted acrylic acid. The radiation resist material is applied to a board to be processed so as to form a resist layer, and the resist layer is exposed by radiation, baked, and developed so as to form a resist pattern. Since the material is an amplifying type generating acid when the material reacts, the sensitivity thereof is high, and at an exposed portion, carboxylic acid is produced so a to be alkali soluble. Like this, patterning can be performed by using the change of the polarity of a polymer, it is possible to obtain the pattern having no swelling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation sensitive material and a pattern forming method using the same.

In recent years, integration of semiconductor integrated circuits has progressed, and LSI and VLSI have been put into practical use. With this, the minimum line width of wiring patterns has reached submicron, and there is a tendency for further miniaturization. .. Here, in forming a fine pattern, a resist is coated on a substrate on which a thin film is formed, and after selective exposure, development is performed to form a resist pattern, dry etching is performed using this as a mask, and then the resist is formed. It is essential to use a photo-etching technique for obtaining a thin film pattern by dissolving and removing the. Ultraviolet rays were initially used as the light source for this photo-etching technique, but sub-micron width resolution is not possible due to wavelength restrictions. Instead, far-ultraviolet rays, electron beams, X-rays with short wavelengths are used. Resolution of submicron width has come to be performed using a line as a light source. The present invention relates to these radiation resist materials.

[0003]

2. Description of the Related Art Conventionally, many resists based on a phenol resin have been developed. However,
Since these materials contain an aromatic ring, they absorb a large amount of light, and therefore, it is not possible to obtain pattern accuracy sufficient for miniaturization with such materials.

On the other hand, use of polymethylmethacrylate (PMMA) or the like as a resin that absorbs less light has been studied, but these materials do not have sufficient dry etching resistance because they do not contain an aromatic ring.

[0005]

As described above, in order to realize a submicron fine pattern, it has excellent transparency to ionizing radiation, especially far-ultraviolet light, and has sufficient dry etching resistance. A light-sensitive material is required, and therefore, the present invention has an object to put into practical use a light-sensitive material for radiation which has both of these characteristics.

[0006]

In order to solve the above-mentioned problems, the present invention comprises an acrylic acid ester or an α-substituted acrylic acid ester having an adamantane skeleton in the ester moiety and a tetrahydropyranyl ester of acrylic acid or α-substituted acrylic acid. A resist material composed of a copolymer is provided.

It is possible to form a resist pattern by applying the radiation resist material of the present invention on a substrate to be processed to form a resist layer, exposing the resist layer to radiation, baking, and then developing. it can.

We have already proposed a radiation-sensitive material having an adamantane structure in the ester part. In the present invention, a copolymer of an acrylate monomer having an adamantane structure in the ester portion and tetrahydropyranyl acrylate is introduced to obtain a material which is excellent in transparency and dry etching property and can form a pattern with high sensitivity. Is a successful one.

[0009]

The present invention provides a sensitized material having excellent transparency to ionizing radiation, especially far-ultraviolet light, sufficient etching resistance, and high sensitivity, and an acrylic ester having an adamantane skeleton in the ester portion or α-substituted. A material comprising a copolymer of acrylic acid ester and tetrahydropyranyl ester of acrylic acid or α-substituted acrylic acid is used.

The photoacid generator produces an acid upon exposure (light irradiation). The acid generated by exposure acts as a catalyst, and the following reaction occurs in the exposed area by heating.

[Chemical 1] In the above formula, X and Y each represent H or —CH ₃ .

As mentioned above, this material has high sensitivity because it is an amplification type that regenerates an acid when a reaction occurs. In the exposed area, carboxylic acid is produced and becomes alkali-soluble.
In this way, patterning can be performed by using the change in polarity of the polymer, so that a pattern without swelling can be obtained.

Examples of the acid generator used include the following compounds. 1. Triphenylsulfonium salt

[Chemical 2] In the above formulas, X ^- is _{^{PF 6 -, AsF 6 -,}} SbF 6 -, BF 4 - or
CF ₃ SO ₃ ^- represents a.

2. Diphenyliodonium salt

[Chemical 3] In the above formulas, X ^- is _{^{PF 6 -, AsF 6 -,}} SbF 6 -, BF 4 - or
CF ₃ SO ₃ ^- represents a.

3. Sulfonic acid compound

[Chemical 4]

4. Halide

[Chemical 5] In the above formula, X represents halogen.

[0016]

EXAMPLES The present invention will be further described below with reference to examples. Comparative Example 1 Using azobisisobutyronitrile (AIBN) as a polymerization initiator, adamantyl methacrylate and t-butyl methacrylate were polymerized in 1,4-dioxane at 80 ° C. for 8 hours, and then hexane was used. As a result of reprecipitation purification by
A copolymer having a dispersity of 13000, a dispersity of 1.61, and a copolymerization ratio of 60:40 was obtained. A solution of this synthesized adamantyl methacrylate / t-butyl methacrylate copolymer (60:40) and triphenylhexafluoroantimonate (10% by weight based on the polymer) in cyclohexanone (20% by weight).
It was created. This is coated on a Si wafer, then 100
The film was baked at 0 ° C. for 20 minutes to form a film having a thickness of 0.5 μm. K
After exposure with an rF excimer stepper, baking was performed at 100 ° C. for 60 seconds. Then, it was developed with an alkaline developer for 1 minute. In addition, CF ₄ / O ₂ (0.95 / 0.05), 0.3 Torr, 3
Etching was performed under the condition of 00W. As a result, the dry etching resistance was equal to or higher than that of Nagase positive resist 820 (Nagase Sangyo), but the sensitivity was as low as 200 mJ / cm ² .

Example 1 Synthesis of adamantyl methacrylate / tetrahydropyranyl methacrylate copolymer In a reaction vessel, a magnetic stirrer coated with Teflon, 7.0 g (33.6 mmol) adamantyl methacrylate, 5.72 g (33.6 mmol) Tetrahydropyranyl methacrylate and 33.6 ml of toluene, 552 mg
(3.36 mmol, 5 mol%) of azobisisobutyronitrile was added, and the mixture was stirred at 75 ° C for 6 hours under a nitrogen atmosphere. The reaction solution is precipitated with 2.5 l of hexane containing a small amount of hydroquinone and 25 ml of ethanol, the white precipitate is suction filtered through a G3 glass filter and placed in a vacuum desiccator at 40
Dry for 6 hours at 0.1 ° C and 0.1 mmHg vacuum. Dissolve the obtained white powder in tetrahydrofuran again, and add 30 ml.
And reprecipitate with 2.5 l of hexane containing 25 ml of ethanol. The white precipitate is suction filtered with a G3 glass filter and placed in a vacuum desiccator at 40 ° C and 0.1 mmHg.
It is dried for 16 hours at a reduced pressure of. The yield of the obtained copolymer was 11.86 g (93.2%), the molecular weight was 18,000, and the dispersity was 1.7.
3, copolymerization ratio (adamantyl: tetrahydropyranyl)
= 54:46. The transmittance of this copolymer at 248 nm was 92%, which was higher than that of the phenol novolac resin (30%).

Example 2 Synthesis of Adamantyl Methacrylate / Tetrahydropyranyl Methacrylate Copolymer In Example 1, 7.0 g of adamantyl methacrylate was added.
(33.6 mmol), tetrahydropyranyl methacrylate 2.
45 g (14.1 mmol), toluene 24 ml, 394 mg (2.
The same reaction was carried out using 4 mmol (5 mol%) of azobisisobutyronitrile. The yield of the obtained copolymer is 7.
62 g (80.6%), molecular weight 22000, dispersity 1.84, copolymerization ratio (adamantyl: tetrahydropyranyl) = 70: 30
Is. The transmittance of this copolymer at 248 nm is 92%.
And was higher than that of phenol novolac resin (30%).

Example 3 Adamantyl Methacrylate / Tetrahydropyranyl Methacrylate Copolymer (54:46) Synthesized in Example 1 and Benzoin Tosylate (20% by Weight Based on Polymer)
Xylene solution (20% by weight) was prepared. This is Si
Apply on wafer, then bake at 100 ° C for 20 minutes
A 0.5 μm thick film was formed. After exposure with a KrF excimer stepper, baking was performed at 100 ° C. for 60 seconds. Then, it was developed with an alkaline developer for 1 minute. The sensitivity was 30 mj / cm ² , and a 0.4 μm line and space (L & S) pattern was resolved. Furthermore, CF ₄ / O ₂ (0.95 / 0.05), 0.3 Tor
As a result of etching under conditions of r and 300 W, dry etching resistance equal to or higher than that of Nagase positive resist 820 (Nagase Sangyo) was shown.

Example 4 Adamantyl Methacrylate / Tetrahydropyranyl Methacrylate Copolymer (70:30) Synthesized in Example 2 and Benzoin Tosylate (20% by Weight Based on Polymer)
Xylene solution (20% by weight) was prepared. This is Si
Apply on wafer, then bake at 100 ° C for 20 minutes
A 0.5 μm thick film was formed. After exposure with a KrF excimer stepper, baking was performed at 100 ° C. for 60 seconds. Then, it was developed with an alkaline developer for 1 minute. The sensitivity was 60 mj / cm ² , and 0.4 μm L & S pattern was resolved. Furthermore, CF ₄
As a result of etching under the conditions of / O ₂ (0.95 / 0.05), 0.3 Torr, and 300 W, dry etching resistance equal to or higher than that of Nagase positive resist 820 (Nagase Sangyo) was shown.

Example 5 A solution of adamantyl methacrylate / tetrahydropyranyl methacrylate (70:30) synthesized in Example 2 and triphenylhexafluoroantimonate (10% by weight based on the polymer) in cyclohexanone (20 % By weight). This was coated on a Si wafer and then baked at 100 ° C. for 20 minutes to form a 0.5 μm thick film. After exposure with a KrF excimer stepper, baking was performed at 100 ° C. for 60 seconds. Then, it was developed with an alkaline developer for 1 minute. The sensitivity was 10 mJ / cm ² , and 0.4 μm L & S pattern was resolved. Furthermore, CF ₄ / O ₂ (0.95 / 0.05), 0.3
As a result of etching under the conditions of Torr and 300 W, dry etching resistance equal to or higher than that of Nagase positive resist 820 (Nagase Sangyo) was shown.

Example 6 Synthesis of adamantyl methacrylate / tetrahydropyranyl acrylate copolymer In a reaction vessel, a Teflon-coated magnetic stir bar, 7.0 g (33.6 mmol) adamantyl methacrylate, 5.72 g (36.7 mmol) Tetrahydropyranyl acrylate and 33.6ml of toluene, 552mg
(3.36 mmol, 4.7 mol%) of azobisisobutyronitrile is added, and the mixture is stirred under a nitrogen atmosphere at 75 ° C. for 6 hours. The reaction solution was precipitated with 2.5 l of hexane containing a small amount of hydroquinone and 25 ml of ethanol, and the white precipitate was suction filtered with a glass filter of G3 and placed in a vacuum desiccator for 4 times.
It is dried at 0 ° C. and a reduced pressure of 0.1 mmHg for 6 hours. The white powder obtained is dissolved again in tetrahydrofuran and 3
Make 0 ml of solution and reprecipitate with 2.5 l of hexane containing 25 ml of ethanol. The white precipitate is suction filtered with a G3 glass filter, and then placed in a vacuum desiccator at 40 ° C., 0.1
Dry for 16 hours at a reduced pressure of mmHg. The yield of the obtained copolymer was 11.5 g (90.4%), the molecular weight was 17,000, and the dispersity was 1.
63, Copolymerization ratio (adamantyl: tetrahydropyranyl)
= 62: 38. The transmittance of this copolymer at 248 nm was 98%, which was higher than that of the phenol novolac resin (30%).

Example 7 A solution of adamantyl methacrylate / tetrahydropyranyl acrylate copolymer (62:38) synthesized in Example 6 and benzoin tosylate (20% by weight) in xylene (20% by weight). It was created. Apply this on a Si wafer, then bake at 100 ° C for 20 minutes
A 0.5 μm thick film was formed. After exposure with a KrF excimer stepper, baking was performed at 100 ° C. for 60 seconds. Then, it was developed with an alkaline developer for 1 minute. The sensitivity was 30 mJ / cm ² , and 0.4 μm L & S pattern was resolved. Furthermore, CF ₄
As a result of etching under the conditions of / O ₂ (0.95 / 0.05), 0.3 Torr, and 300 W, dry etching resistance equal to or higher than that of Nagase positive resist 820 (Nagase Sangyo) was shown.

In the above example, the case where the alkali development is performed has been described, but the development can also be performed using anisole, and in this case, a negative pattern is obtained. Alternatively, development can be carried out using a lower alcohol, in which case a positive pattern is obtained.

[0025]

As described above, according to the present invention, an ester monomer of an unsubstituted or α-substituted acrylic acid having an adamantane skeleton in the ester portion which does not absorb in the short wavelength region is unsubstituted or α-substituted. By copolymerizing tetrahydropyranyl acrylic acid, it is possible to form a pattern with high sensitivity while maintaining excellent transparency and dry etching resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/027 21/312 D 8518-4M

Claims (2)

[Claims] 1. A resist material comprising a copolymer of an acrylic acid ester or an α-substituted acrylic acid ester having an adamantane skeleton in the ester portion and a tetrahydropyranyl ester of acrylic acid or an α-substituted acrylic acid. 2. A resist material according to claim 1 is applied on a substrate to be processed to form a resist layer, and the resist layer is exposed to radiation, baked and then developed to form a resist pattern. A method for forming a pattern.