KR20030000449A - Photosensitive polymer having fluorinated cyclic monomer and resist composition comprising the same - Google Patents

Abstract

PURPOSE: A photosensitive polymer containing a fluorine-substituted cyclic monomer and a resist composition containing the composition are provided, which is transparent to the light less than 193 nm and shows a good adhesive property to a membrane, a large dry etching resistance and a good contrast characteristic. CONSTITUTION: The photosensitive polymer contains a fluorine-substituted cyclic monomer represented by the formula, wherein at least one between X and Z is a fluorocarbon of C1-C3; and Y is a fluorocarbon of C1-C3, O, S, NH, NCH3, Si(CH3)2, Si(C2H5)2, carbonyl, or ester group. The resist composition comprises the photosensitive polymer; 1-15 wt% of a photoacid generator; and optionally 0.01-2.0 wt% of an organic base. Preferably the photoacid generator is selected from the group consisting of a triarylsulfonium salt, a diarylodonium salt, a sulfonate and their mixtures; and the organic base is selected from the group consisting of triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, diethanolamine and their mixtures.

Description

Photosensitive polymer having a fluorine-substituted cyclic monomer and a resist composition comprising the same {Photosensitive polymer having fluorinated cyclic monomer and resist composition comprising the same}

As the semiconductor manufacturing process becomes complicated and the degree of integration of semiconductor devices increases, fine pattern formation is required. In the case of devices having a capacity of 1 gigabit or more of semiconductor devices, a pattern size of 0.2 µm or less is required for the design rule. Accordingly, there is a limitation in using a resist material using a conventional KrF excimer laser (248 nm). Lithography techniques using ArF excimer laser (193 nm) as an energy exposure source have emerged. Although 193 nm lithography technology will be applied to industrialization within the 100 nm technology unit, the demand for smaller specific sizes requires the introduction of new lithography technology. Thus, as of 1999, interest in F ₂ excimer laser (157 nm) lithography, which is capable of 70 nm technology units, has greatly increased, and research into resist materials for using the new F ₂ excimer laser (157 nm) has recently been made. A lot has been going on. Basically, micronized pattern size is achieved, including high transmittance at 157 nm, strong plasma etch resistance, adhesion to substrate film, solid mechanical strength at process temperature, applicability of existing water-soluble developers, and excellent dissolution characteristics. The development of a resist for an F ₂ excimer laser having the characteristics required for this should be preceded.

Current resists for F ₂ excimer lasers include alternating polymers of norbornene and maleic anhydride (Formula 1) containing fluorine substituents published by the University of Texas (Chemical Formula 1) or tetrafluoroethylene and norbornene cosins published by DuPont Polymers (Formula 2) and the like are known.

However, these materials have a disadvantage in that sufficient resolution cannot be achieved due to insufficient transmittance, dry etching resistance, adhesion to a substrate, and photosensitivity.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a photosensitive polymer having improved resist properties required to realize an extremely fine pattern size.

Another object of the present invention is to provide a resist composition composed of the photosensitive polymer.

The technical problem is achieved by a photosensitive polymer comprising a fluorine-substituted cyclic monomer structure. Specifically, the fluorine-substituted cyclic monomer may be O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group, or an ester group based on fluorocarbons having 1-3 carbon atoms. It is a monomer of the form which substituted fluorine to the cyclic structure which this couple | bonded.

The photosensitive polymer is an alternating polymer in which the fluorine-substituted cyclic monomer and the norbornene monomer are alternately polymerized.

In addition, the photosensitive polymer may be a photosensitive polymer of at least a terpolymer consisting of the fluorine-substituted cyclic monomer, the norbornene derivative, and at least one monomer selected from the group consisting of acrylate, methacrylate, acrylic acid and methacrylic acid. .

The resist composition according to the present invention for achieving the above another technical problem includes the photosensitive polymer and PAG mixed in a ratio of 1 to 15% by weight.

The chemically amplified photoresist composition according to the present invention may further include 0.01 to 2% by weight of an organic base based on the weight of the photosensitive polymer.

Hereinafter, a photosensitive polymer and a resist composition including the same according to the present invention will be described. Moreover, the preferable photolithography process using a resist composition is also demonstrated. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided for complete information.

Photosensitive polymer

The photosensitive polymer according to the present invention comprises a fluorine substituted cyclic monomer as a component.

Specifically, a fluorine substituted cyclic monomer such as the following Chemical Formula 3 is used.

Wherein at least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H) ₅ ) _{2, a} carbonyl group or an ester group.

The photosensitive polymer according to the present invention is an alternating polymer in which the fluorine-substituted cyclic monomer and the norbornene monomer are alternately polymerized as in the following Chemical Formula 4.

Wherein R ₁ and R ₂ are acid-labile groups that cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms,

At least one of X and Z is fluorocarbon having 1-3 carbon atoms,

Y is a group having a carbon number of 1 to 3 fluorocarbon, O, S, NH, NCH 3, Si (CH 3) 2, Si (C 2 H 5) 2, or an ester group.

The alternating polymer of Chemical Formula 4 may be obtained by general radical polymerization by mixing a norbornene derivative and a fluorine-substituted cycloalkyne compound in a 1: 1 ratio, and may be bulk polymerization or solution polymerization. As the polymerization initiator, all general radical initiators such as AIBN can be used, and in solution polymerization, both polar solvents such as THF and dioxane and nonpolar solvents such as cyclohexane can be used.

In addition, the photosensitive polymer according to the present invention includes a fluorine-substituted cyclic monomer, a norbornene derivative, and at least one monomer selected from the group consisting of acrylate, methacrylate, acrylic acid and methacrylic acid, as shown in Formula 5 below. Photosensitive polymers more than the terpolymer made up may be used.

Wherein R ₁ , R ₂ and R ₃ are acid-labile groups which cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms,

R ₄ is hydrogen or a methyl group,

At least one of X and Z is fluorocarbon having 1-3 carbon atoms,

Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group or an ester group,

m is 0.5 to 1, (n + p) is 0.0 to 0.5, and (m + n + p) is 1.

The weight average molecular weight of the photosensitive polymer is 3,000 to 100,000.

The photosensitive polymer represented by Chemical Formula 5 may also be obtained by mixing and polymerizing a norbornene derivative, a fluorine-substituted cycloalkyne compound, and a (meth) acrylate. It can be prepared according to the same method as the alternating polymer.

Chemically Amplified Photoresist Compositions

The chemically amplified photoresist composition according to the present invention is composed of the photosensitive polymer and photoacid generator (PAG) described above.

PAG is preferably mixed in a proportion of 1 to 15% by weight based on the weight of the photosensitive polymer.

As the PAG, triarylsulfonium salts, diaryliodonium salts, sulfonates, N-hydroxysuccinimide triflate or mixtures thereof can be used. For example, triphenylsulfonium triflate, triphenylsulfonium antimonate, diphenyliodonium triflate, diphenyliodonium antimonate, Methoxydiphenyliodonium triflate, di-t-butyldiphenyliodonium triflate, 2,6-dinitrobenzyl sulfonate, Pyrogallol tris (alkylsulfonates), N-hydroxysuccinimide triflate, norbornene-dicarboximide triflate, triphenylsulf Triphenylsulfonium nonaflate, diphenyliodonium nonaflate, methoxydiphenyliodonium no naflate), di-t-butyldiphenyliodonium nonaflate, N-hydroxysuccinimide nonaflate, norbornene dicarboximide nonaflate ), Triphenylsulfonium perfluorooctanessulonates, diphenyliodonium perfluorooctanesulfonates, methoxydiphenyliodonium perfluorooctane sulfonates, di-t- Di-t-butyldiphenyliodonium perfluorooctanesulfonates, N-hydroxysuccin imide perfluorooctanesulfonates, norbornene dicarboximide perfluorooctanesulfonate (norbornene dicarboximide perfluorooctane sulfonates) or mixtures thereof as photoacid generators Can be used.

Preferably the photoresist composition according to the invention further comprises 0.01 to 2.0% by weight of organic base. The organic base consists of a compound consisting of tertiary amines alone or by mixing two or more kinds. Particularly preferred organic bases include triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, diethanolamine, and triethanolamine (triethanolamine). triethanolamine) or mixtures thereof. After exposure, the organic base is added to prevent the problem that the acid generated in the exposed portion diffuses into the non-exposed portion to form a non-exposed portion, which also hydrolyzes and deforms the pattern.

Moreover, it is preferable that the photoresist composition which concerns on this invention further contains surfactant of the organic or salt component about 30-200 ppm. The surfactant performs the function of allowing the photoresist composition to be uniformly coated on the substrate.

On the other hand, including a dissolution inhibitor (0.1 to 50% by weight) is effective for improving the dry etching resistance and contrast.

The resist composition according to the present invention is suitable for the microphotographic etching process, and particularly for forming the fine pattern with a design rule of 0.1 μm or less using an F ₂ excimer laser as an exposure source.

First, the photoresist composition described above is applied onto a substrate on which an object to be patterned is formed to form a photoresist film having a predetermined thickness. The photoresist film is formed to a thickness of 0.5 µm to 0.05 µm. Since the resist composition according to the present invention has excellent adhesion to the lower film quality, the photoresist film is applied very well. Subsequently, a pre-exposure bake is performed on the photoresist film. The pre-exposure bake is performed at 80 ° C to 150 ° C for 30 seconds to 300 seconds. After the pre-exposure bake step, the photoresist film is exposed using a mask on which a predetermined pattern is formed. As an exposure source, an exposure source using a wavelength of 193 nm or less, preferably an F ₂ excimer laser using a wavelength of 157 nm is used. By exposure, acid is generated from the photoacid generator in the photoresist film, and the generated acid catalyzes to hydrolyze the photosensitive polymer to form a large amount of hydrophilic groups in the photoresist film of the exposed portion. Therefore, the polarity of the photoresist film of the exposed portion and the polarity of the photoresist film of the unexposed portion are remarkably different. In other words, the contrast is significantly increased.

After the exposure is completed, post-exposure bake (PEB) is performed before development. The post-exposure heat treatment is performed to further activate the acidolysis reaction by the acid catalyst in the exposed portion. Subsequently, when a developing process is performed using an appropriate developer, a photoresist pattern having an excellent pattern profile can be formed at an excellent resolution. The developer to be used uses a developer, such as 2.38% by weight of tetramethylammonium hydroxide (TMAH), at a concentration used in a conventional process.

After forming the photoresist pattern, the film to be patterned is etched to form a desired pattern. The resist composition according to the present invention is highly resistant during etching. Thus, it is possible to form a pattern of good profile with accurate critical dimensions.

The invention is described in more detail with reference to the following examples, which are not intended to limit the invention.

Example 1 Preparation of Alternating Polymers

<Example 1-1>

In Formula 4, a copolymer having R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -O-CH ₂ -O-CH ₃ , X = CF ₂ , Y = CF ₂ , Z = none Prepared as. After dissolving 12.0 g of norbornene and 8.0 g of hexacyclobutene using methoxymethyl ether as a deprotector in 20 g of THF, 0.38 g of dimethyl 2,2'-azobisisobutyrate was added thereto. Degassing at −78 ° C. and complete purge for about 2 hours with nitrogen gas. After raising the temperature to room temperature, the polymerization was carried out at 70 ℃ for 20 hours.

After the reaction was completed, the resultant was precipitated twice in excess of isoflophyll alcohol, filtered and dried in a vacuum oven for 24 hours to obtain a copolymer. (Yield 45%). The weight average molecular weight (Mw) of the obtained product was 6,700, and polydispersity (Mw / Mn) was 2.6.

<Example 1-2>

In Formula 4, a copolymer having R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -O-CH ₂ -O-CH ₃ , X = CF ₂ , Y = O, Z = CF ₂ , Prepared as. 12.0 g of norbornene and 8.7 g of perfluoro-2,5-dihydrofuran were dissolved in 20 g of THF, and 0.4 g of dimethyl 2,2'-azobisisobutyrate was added thereto. . After the process was carried out in the same manner as in Example 1-1 to obtain a copolymer. (Yield 42%). The weight average molecular weight (Mw) of the obtained product was 5,900, and polydispersity (Mw / Mn) was 2.3.

<Example 1-3>

In Formula 4, a copolymer having R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -O-CH ₂ -O-CH ₃ , X = CF ₂ , Y = CF ₂ , Z = CF ₂ , It was prepared as follows. After dissolving 12.0 g of norbornene and 10.4 g of octafluorocyclopentene using methoxymethyl ether as a deprotector in 20 g of THF, 0.6 g of dimethyl 2,2'-azobisisobutyrate was added thereto. After the process was carried out in the same manner as in Example 1-1 to obtain a copolymer. (Yield 43%). The weight average molecular weight (Mw) of the obtained product was 6,200, and polydispersity (Mw / Mn) was 3.1.

Example 2. Preparation of Terpolymer

<Example 2-1>

In Formula 5, R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -OC (CH ₃ ) ₃ , R ₃ = CH ₂ CH ₂ (CF ₂ ) ₅ CF ₃ , R ₄ = CF ₃ , X A copolymer with = CF ₂ , Y = CF ₂ , Z = none and p = 0 was prepared as follows. Dissolve 10.0 g of norbornene, 6.4 g of hexafluorocyclobutene, and 5.2 g of tridecafluorooctyl methacrylate in 20 g of THF using t-butyl ether as a deprotector, followed by dimethyl 2,2'-azobisisobutyrate 0.82 g was added. Degassing at −78 ° C. and complete purge for about 2 hours with nitrogen gas. After raising the temperature to room temperature, the polymerization was carried out at 70 ℃ for 20 hours.

After the reaction was completed, the resultant was precipitated twice in excess of isoflophyll alcohol, filtered and dried in a vacuum oven for 24 hours to obtain a terpolymer. (Yield 65%). The weight average molecular weight (Mw) of the obtained product was 8,600, and polydispersity (Mw / Mn) was 2.9.

<Example 2-2>

In Formula 5, R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -OC (CH ₃ ) ₃ , R ₃ = CH ₂ CH ₂ (CF ₂ ) ₅ CF ₃ , R ₄ = CF ₃ , X A copolymer with = CF ₂ , Y = CF ₂ , Z = CF ₂ and p = 0 was prepared as follows. Dissolve 10.0 g of norbornene, 8.0 g of octafluorocyclopentene, and 5.4 g of tridecafluorooctyl methacrylate using t-butyl ether as a deprotector in 20 g of THF, followed by dimethyl 2,2'-azobisisobutyrate 0.82 g was added. After the process was carried out in the same manner as in Example 2-1 to obtain a terpolymer (yield 63%). The weight average molecular weight (Mw) of the obtained product was 7,600, and polydispersity (Mw / Mn) was 3.3.

<Example 2-3>

In Formula 5, R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -OC (CH ₃ ) ₃ , R ₃ = CH ₂ CH ₂ (CF ₂ ) ₅ CF ₃ , R ₄ = CF ₃ , X A copolymer with = CF ₂ , Y = O, Z = CF ₂ and p = 0 was prepared as follows. Dissolve 10.0 g of norbornene, 7.5 g of perfluoro-2,5-dihydrofuran, and 5.0 g of tridecafluorooctyl methacrylate in 20 g of THF using t-butyl ether as a deprotector, followed by dimethyl 2,2 ' 0.75 g of azobisisobutyrate was added. After the same process as in Example 2-1 to obtain a terpolymer (yield 59%). The weight average molecular weight (Mw) of the obtained product was 7,200, and polydispersity (Mw / Mn) was 3.1.

Example 3. Preparation of Tetrapolymer

In Formula 5, R ₁ = H, R ₂ = CH ₂ -C (CF ₃ ) ₂ -OC (CH ₃ ) ₃ , R ₃ = CH ₂ CH ₂ (CF ₂ ) ₅ CF ₃ , R ₄ = CF ₃ , X A tetrapolymer having = CF ₂ , Y = CF ₂ , Z = none was prepared as follows. Dissolve 10.0 g of norbornene, 6.2 g of hexafluorocyclobutene, 2.5 g of tridecafluorooctyl methacrylate and 2.0 g of methacrylate in 20 g of THF, using t-butyl ether as a deprotector, followed by dimethyl 2,2 '. 0.82 g of azobisisobutyrate was added. Degassing at −78 ° C. and complete purge for about 2 hours with nitrogen gas. After raising the temperature to room temperature, the polymerization was carried out at 70 ℃ for 20 hours.

After the reaction was completed, the resultant was precipitated twice in excess of isoflophyl alcohol, filtered and dried in a vacuum oven for 24 hours to obtain a tetrapolymer. (Yield 66%). The weight average molecular weight (Mw) of the obtained product was 8,600, and polydispersity (Mw / Mn) was 2.9.

Example 4 Preparation of Resist Composition and Formation of Photoresist Pattern

1.0 g of the polymers obtained in Examples 1 to 3 together with 0.01 g of triphenylsulfonium trifluoromethanesulfonate (triplate), which is PAG, and 3.2 mg of triisodecylamine, which is an organic base, respectively, are propylene glycol monomethyl ether acetate (PGMEA). After completely dissolving in a mixed solution of 4.0 g and 4.0 g of cyclohexanone, the respective resist compositions were obtained by using a 0.2 μm membrane filter, respectively. These resist compositions were coated on a silicon wafer treated with an organic antireflection film to a thickness of about 0.2 탆 each. Thereafter, each wafer coated with the resist composition was soft baked at a temperature of 130 ° C. for 90 seconds, exposed using an F ₂ excimer laser stepper (NA = 0.6), and then at a temperature of 120 ° C. for 60 seconds. PEB was performed.

Thereafter, using a 38% by weight of tetramethylammonium hydroxide (TMAH) solution was developed for about 60 seconds to form a resist pattern. As a result, when the exposure dose amount was set to about 8 to 30 mJ / cm 3, it was confirmed that a line and space pattern of 0.17 to 0.23 μm was obtained.

The polymer according to the present invention is easy to manufacture and the manufacturing cost is low. In addition, the resist composition composed of the polymer according to the present invention has excellent adhesion properties to the underlying film quality, high resistance to dry etching, and high contrast properties. In addition, since the transmittance is high at a wavelength of 193 nm or less, particularly at a wavelength of 157 nm or less, a pattern of 0.1 μm or less, for example, 70 nm or less can be formed.

Claims (10)

A photosensitive polymer comprising a fluorine-substituted cyclic monomer represented by the following formula Wherein at least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H) ₅ ) _{2, a} carbonyl group or an ester group. The photosensitive polymer as claimed in claim 1, wherein the photosensitive polymer has the following structure. Wherein R ₁ and R ₂ are acid-labile groups that cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms, At least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group or an ester group, The weight average molecular weight of the photosensitive polymer is 3,000 to 100,000. The photosensitive polymer as claimed in claim 1, wherein the photosensitive polymer has the following structure. Wherein R ₁ , R ₂ and R ₃ are acid-labile groups which cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms, R ₄ is hydrogen or a methyl group, At least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group or an ester group, m is 0.5 to 1, (n + p) is 0.0 to 0.5, (m + n + p) is 1, The weight average molecular weight of the photosensitive polymer is 3,000 to 100,000. The photosensitive polymer containing a fluorine-substituted cyclic monomer represented by the following formula and Resist composition comprising 1 to 15% by weight of PAG Wherein at least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H) ₅ ) _{2, a} carbonyl group or an ester group. The resist composition of claim 4, wherein the photosensitive polymer has the following structure. Wherein R ₁ and R ₂ are acid-labile groups that cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms, At least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group or an ester group, The weight average molecular weight of the photosensitive polymer is 3,000 to 100,000. The resist composition of claim 4, wherein the photosensitive polymer has the following structure. Wherein R ₁ , R ₂ and R ₃ are acid-labile groups which cause a chemical reaction by hydrogen or an acid having 2 to 12 carbon atoms, R ₄ is hydrogen or a methyl group, At least one of X and Z is fluorocarbon having 1-3 carbon atoms, Y is fluorocarbon having 1-3 carbon atoms, O, S, NH, NCH ₃ , Si (CH ₃ ) ₂ , Si (C ₂ H ₅ ) _{2, a} carbonyl group or an ester group, m is 0.5 to 1, (n + p) is 0.0 to 0.5, (m + n + p) is 1, The weight average molecular weight of the photosensitive polymer is 3,000 to 100,000. The resist composition of claim 4, wherein the PAG is formed of a triarylsulfonium salt, a diarylodonium salt, a sulfonate, or a mixture thereof. The resist composition according to claim 4, further comprising 0.01 to 2.0% by weight of organic base. The resist composition of claim 8, wherein the organic base is triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, diethanolamine, triethanolamine, or mixtures thereof. 5. The resist composition of claim 4, further comprising 30-200 ppm of a surfactant and / or 0.1-50% by weight of a dissolution inhibitor.