KR20030023198A - Photosensitive polymer containing alkyloxymethylether protecting group and resist composition comprising the same - Google Patents

Abstract

PURPOSE: A photosensitive polymer containing a protection group of an alkyl oxymethyl ether structure and a chemical amplification resist composition containing the polymer are provided, to improve the transmittance to the F2 excimer laser of a wavelength of 157 nm and the etching resistance. CONSTITUTION: The photosensitive polymer comprises a repeating unit having a protection group represented by the formula, wherein R1 and R2 are H or F, respectively, and at least one between R1 and R2 is F; and R3 is a cyclic hydrocarbon group of C5-C20 unsubstituted or substituted with F. The resist composition comprises the photosensitive polymer; and a photoacid generator. Also the resist composition comprises the photosensitive polymer which is obtained by the polymerization of a first monomer unit having a protection group represented by the formula and at least one second monomer unit selected from the group consisting of acrylate, methacrylate, maleic anhydride, norbornene, tetrafluoroethylene and sulfur dioxide; and a photoacid generator.

Description

Photosensitive polymer containing a protecting group of the alkyloxymethyl ether structure and a resist composition containing the same {Photosensitive polymer containing alkyloxymethylether protecting group and resist composition comprising the same}

The present invention relates to photosensitive polymers and chemically amplified resist compositions, and more particularly to photosensitive polymers containing fluorine and resist compositions comprising the same.

As the semiconductor manufacturing process becomes complicated and the degree of integration of semiconductor devices increases, fine pattern formation is required. Furthermore, in devices with a semiconductor device having a capacity of 1 gigabit or more, a pattern size of 0.1 μm or less is required, and thus there is a limit to using a resist material using a conventional KrF excimer laser (248 nm). have. Therefore, a lithography technique using ArF excimer laser (193 nm), which is a new energy exposure source, has been developed and developed. The ArF resist composition has been focused on acrylic polymer and COMA (cycloolefin-maleic anhydride).

Recently, research on lithography using an F ₂ (157 nm) excimer laser that generates short wavelengths in order to further reduce the pattern size has been actively conducted. The use of existing KrF or ArF resists at short wavelengths of 157 nm is not very suitable for use as resists for 157 nm because their transmittance is very low. Therefore, a new polymer having a transparent structure at 157 nm is required to prepare a resist for 157 nm. The structure of the chemical component that can be dissolved in the developer is phenol, carboxylic acid, α-fluorocarbon substituted alcohol or hydroxysilane as shown in the formula (1). hydroxy silane) structure.

Of these, phenol and carboxylic acid have a significantly low transmittance for 157 nm. In contrast, α-fluorocarbon-substituted methanol and hydroxysilane, which correspond to the other two structures, showed relatively high transmittances over a wavelength of 157 nm, and thus became a main research subject.

However, according to recent studies, phenol and carboxylic acid derivatives have been introduced into 157 nm polymers by appropriate substitution of fluorine to increase transmittance and to increase contrast.

Although it has an ester group, it can be seen that the structure in which fluorocarbon is appropriately substituted for this structure is used because of the advantage that the acrylate structure is easily obtained with high permeability. The structure is illustrated in Formula (2).

In particular, t-butyl trifluoromethyl acrylate is widely used as a monomer for improving contrast. Aromatic hydrocarbon monomers having low permeability at 157 nm can also be used as resists by increasing the transmittance by converting them into hexafluoroisopropanol substituted styrene structures. The structure is illustrated in the formula (3).

In addition, a poly (norbornene sulfone) structure as shown in formula (4) has been proposed.

In this structure, maleic anhydride, which is an adhesion promoter, is absorbed at 157 nm by a carbonyl group in COMA (cycloolefin-maleic anhydride) structure, thereby improving transmittance by converting it into sulfone structure.

In addition, there are active studies on resists having a copolymer structure of tetrafluoroethylene and norbornylene derivatives as shown in Formula 5, and ring ethers in the main chain of the polymer as shown in Formula 6. Structures in which a (cyclic ether) type structure is introduced have been studied.

Until now, it has been reported that tertiary alkyl groups are mainly used as protecting groups of carboxylic acids, and tBOC (t-butoxycarbonyl) groups are used as protecting groups for hexafluoroisopropanol. In addition, examples of using tetrahydropyran as a protecting group for both carboxylic acid and hexafluoroisopropanol have been disclosed.

It is an object of the present invention to provide a photosensitive polymer which can be used as a resist material having high transmittance with respect to F ₂ (157 nm) excimer laser wavelength and having excellent etching resistance.

Another object of the present invention is to provide a resist composition having high transmittance with respect to the F ₂ (157 nm) excimer laser wavelength and having excellent etching resistance.

In order to achieve the above object, the photosensitive polymer according to the present invention consists of a repeating unit having a protecting group of the following structure.

Wherein R ₁ and R ₂ are each a hydrogen atom or fluorine, at least one of R ₁ and R ₂ is fluorine, and R ₃ is a C ₅ to C ₂₀ fluorine-substituted or unsubstituted ring hydrocarbon group. R ₃ may have any one structure selected from the following structures.

In the formula, x ₁ and x ₂ are integers of 1 to 5, respectively.

Preferably, the photosensitive polymer according to the present invention comprises a repeating unit of the following structure.

Also preferably, the photosensitive polymer according to the present invention comprises a repeating unit of the following structure.

In order to achieve the above another object, the resist composition according to the first aspect of the present invention comprises a photosensitive polymer composed of a repeating unit having a protecting group of the following structure, and a photoacid generator (PAG).

Wherein R ₁ , R ₂ and R ₃ are as defined above.

Moreover, in order to achieve the said another object, the resist composition which concerns on the 2nd aspect of this invention is a 1st monomer unit which has a protecting group of the following structure, an acrylate monomer, a methacrylate monomer, a maleic anhydride monomer, norbornene monomer And a photosensitive polymer comprising a polymerization product with at least one second monomer unit selected from the group consisting of tetrafluoroethylene and sulfur dioxide, and PAG.

Wherein R ₁ , R ₂ and R ₃ are as defined above.

In the resist composition according to the second aspect of the present invention, the photosensitive polymer may include the following structure.

In addition, in the resist composition according to the second aspect of the present invention, the photosensitive polymer may include the following structure.

In addition, in the resist composition according to the second aspect of the present invention, the photosensitive polymer may include the following structure.

In the formula, R ₄ is a hydrogen atom, -CH ₃ or -CF ₃ .

In the resist composition according to the present invention, the weight average molecular weight of the photosensitive polymer is 2,000 to 100,000.

The PAG is included in an amount of 1 to 15% by weight based on the weight of the photosensitive polymer. The PAG may consist of triarylsulfonium salts, diaryliodonium salts, sulfonates or mixtures thereof.

The resist composition according to the present invention may further comprise an organic base. The organic base is included in an amount of 0.01 to 2.0% by weight based on the weight of the photosensitive polymer.

According to the present invention, the fluorine in the C ₅ ~ C ₂₀ provides a photosensitive polymer having a protecting group of alkyloxy ether structure containing a substituted or unsubstituted cyclic hydrocarbon. The resist composition according to the present invention obtained from such a photosensitive polymer has a high transmittance to the F ₂ (157 nm) excimer laser wavelength and is excellent in etch resistance. Thus, excellent lithographic performance can be exhibited when applied to photolithography processes using F ₂ (157 nm) excimer lasers.

Next, preferred embodiments of the present invention will be described in detail.

Synthesis Example 1

Synthesis of Monomers

HCl gas dried in a solution of methanol (20 g) and 1,3,5-trioxane (4.5 g) in pentane (70 ml) was saturated at −4 ° C. for 30 minutes and then stirred for 5 hours. After the reaction, the water layer was separated from the organic layer, and the organic layer was dried over CaCl ₂ . Pentane was removed under reduced pressure and fractional distillation yielded chloromethyl menthylether in 80% yield. (Reference: Liebigs Ann. Chem. 1991 375-379)

Synthesis Example 2

Synthesis of Monomers

Using 3,4,5-trifluorobenzyl alcohol in the same manner as in Synthesis example 1, 3,4,5-trifluorobenzyl chloromethyl ether could be synthesized in a yield of 75%.

Synthesis Example 3

Synthesis of Monomers

The flask containing NaH (1.27 g) and tetrahydrofuran (THF) (30 ml) was charged with nitrogen, and then 3- (5-bicyclo [2.2.1] hepten-2-yl) -1, at -5 ° C. 1,1-trifluoro-2- (trifluoromethyl) -2-propanol (reference: J. of Photopolymer Science and Technology, V 13, No 4, 657, 2000 ) (13.7 g) was added for 20 minutes It was dripped. After raising the reaction temperature to room temperature and reacting for 15 minutes, chloromethyl menthyl ether (10.2 g) was added dropwise at -5 ℃ for 20 minutes. After raising the temperature to 75 ℃, the reaction for 2 hours, ether at room temperature, washed with 1M NaOH solution and separated the organic layer. The water layer was washed three times with ether, the organic layers were collected, rotary evaporation of the solvent, fractional distillation, and 3- (5-bicyclo [2.2.1] hepten-2-yl) -1, in 75% yield. 1,1-trifluoro-2- (trifluoromethyl) -2-propyl menthyloxymethyl ether was synthesized

Synthesis Example 4

Synthesis of Monomers

1- [2,2 in 79% yield using 4- (2- (1,1,3,3-hexafluoro-2-propanol) styrene and chloromethyl menthylether in the same manner as in Synthesis example 3 , 2-trifluoro-1- (menthyloxymethoxy) -1-trifluoromethyl-ethyl] -4-vinyl-benzene could be synthesized.

Synthesis Example 5

Synthesis of Monomers

79% using 4- (2- (1,1,3,3-hexafluoro-2-propanol) styrene and 3,4,5-trifluorobenzyl chloromethyl ether in the same manner as in Synthesis example 3. Synthesized 1- [2,2,2-trifluoro-1- (3,4,5-trifluorobenzylmethyl) -1-trifluoromethyl-ethyl] -4-vinyl-benzene in a yield of Could.

Example 1

Synthesis of Polymer

5 g of 3- (5-bicyclo [2.2.1] hepten-2-yl) -1,1,1-prefluoro-2- (trifluoromethyl) -2-propyl menthyloxymethyl ether, maleic anhydride 1.2 g and 0.2 g of AIBN (azobisisobutyronitrile) were dissolved in 3 g of ethyl acetate, and then reacted at 65 ° C. for 20 hours. Thereafter, the precipitate was precipitated twice in an excess of isopropyl alcohol solution, filtered, and dried in a vacuum oven for 24 hours to recover the polymer. (Yield 46%)

At this time, the weight average molecular weight (Mw) of the obtained product was 8,600, and polydispersity (Mw / Mn) was 2.2.

Example 2

Synthesis of Polymer

1- [2,2,2-trifluoro-1- (menthyloxymethoxy) -1-trifluoromethyl-ethyl] -4-vinyl-benzene 5 g, 1,1,1,3,3,3 3.1 g of hexafluoro-2- (4-vinyl-phenyl) -propan-2-ol and 0.2 g of AIBN were dissolved in 8 g of ethyl acetate, followed by reaction at 65 ° C. Thereafter, the polymer was recovered by reprecipitation in hexane. (Yield 56%)

At this time, the weight average molecular weight (Mw) of the obtained product was 12,000, and polydispersity (Mw / Mn) was 2.1.

Example 3

Synthesis of Polymer

2-trifluoromethylacrylate t-butyl ester 1.14 g, 2-trifluoro-1- (menthyl oxymethoxy) -1-trifluoromethyl-ethyl] -4-vinyl-benzene 2.5 g, 1, 3.1 g of 1,1,3,3,3-hexafluoro-2- (4-vinyl-phenyl) -propan-2-ol and 0.2 g of AIBN were dissolved in 7 g of ethyl acetate and reacted at 65 ° C. Thereafter, the polymer was recovered by reprecipitation in isopropyl alcohol. (Yield 56%)

At this time, the weight average molecular weight (Mw) of the obtained product was 11,200, and polydispersity (Mw / Mn) was 2.6.

Example 4

Synthesis of Polymer

2-trifluoromethylacrylate t-butylester 1.96 g, 1- [2,2,2-trifluoro-1- (3,4,5-trifluorobenzylmethyl) -1-trifluoromethyl -Ethyl] -4-vinyl-benzene 4,4 g, 1,1,1,3,3,3-hexafluoro-2- (4-vinyl-phenyl) -propan-2-ol and 2.7 g AIBN 0.25 g Was dissolved in 9 g of ethyl acetate and reacted at 65 ° C. Thereafter, the polymer was recovered by reprecipitation in isopropyl alcohol. (Yield 77%)

At this time, the weight average molecular weight (Mw) of the obtained product was 15,200, and polydispersity (Mw / Mn) was 2.5.

Example 5

Preparation of Resist Composition

The polymers (1.0 g) obtained in Examples 1, 2, 3 and 4 were triphenylsulfonium trifluoromethanesulfonate (triplate) (0.01 g) and an organic base, which are PAG (photoacid generator). Together with phosphorus triisodecylamine (3.2mg), it was added to a mixed solution of propylene glycol monomethyl ether acetate (PGMEA) (4.0g) and cyclohexanone (4.0g) to completely dissolve, and then filtered using a 0.2 μm membrane filter, respectively. Each resist composition was obtained. These resist compositions were coated on organic Anti-Reflective Coating (ARC) treated Si wafers each about 0.1 μm thick.

Thereafter, each wafer coated with the resist composition was soft baked at a temperature of 120 ° C. for 60 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 2.38% by weight tetramethylammonium hydroxide (TMAH) solution, development was performed for about 30 to 60 seconds to form a resist pattern.

As a result, when the exposure dose amount was set to about 5 to 60 mJ / cm ² , it was confirmed that 0.10 to 0.20 μm line and spaces pattern was obtained.

In the present invention, in order to provide a resist composition having a high transmittance with respect to the F ₂ (157 nm) excimer laser wavelength, a C ₅ to C ₂₀ fluorine substituted or unsubstituted ring hydrocarbon group is included as a protecting group for carboxylic acid and hexafluoroisopropanol. The photosensitive polymer which has a protecting group of the alkyloxy methyl ether structure is provided. In the photosensitive polymer according to the present invention, the protecting group of the alkyloxy methyl ether structure is deprotected by an acid to become an alkali soluble group, so that the resist composition according to the present invention obtained from the photosensitive polymer can provide excellent etching resistance. have. In addition, dissolution contrast characteristics are remarkably improved by including a photosensitive polymer including a bulky alicyclic structure. Thus, when the resist composition according to the present invention is applied to a photolithography process using an F ₂ (157 nm) excimer laser, it exhibits excellent lithography performance, which can be very useful for manufacturing future next-generation semiconductor devices.

The present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. Do.

Claims (20)

A photosensitive polymer comprising a repeating unit having a protecting group of the following structure. Wherein R ₁ and R ₂ are each a hydrogen atom or fluorine, at least one of R ₁ and R ₂ is fluorine, and R ₃ is a C ₅ to C ₂₀ fluorine-substituted or unsubstituted ring hydrocarbon group. The photosensitive polymer according to claim 1, comprising a repeating unit of the following structure. The photosensitive polymer according to claim 1, comprising a repeating unit of the following structure. The photosensitive polymer according to any one of claims 1 to 3, wherein R ₃ has any one structure selected from the following structures. In the formula, x ₁ and x ₂ are integers of 1 to 5, respectively. (a) a photosensitive polymer comprising a repeating unit having a protecting group of the following structure, Wherein R ₁ and R ₂ are each a hydrogen atom or fluorine, at least one of R ₁ and R ₂ is fluorine, and R ₃ is a C ₅ to C ₂₀ fluorine-substituted or unsubstituted ring hydrocarbon group. (b) a resist composition comprising a photoacid generator (PAG). A resist composition according to claim 5, wherein the photosensitive polymer comprises a repeating unit having the following structure. A resist composition according to claim 5, wherein the photosensitive polymer comprises a repeating unit having the following structure. 8. A resist composition according to any one of claims 5 to 7, wherein R ₃ has any structure selected from the following structures. In the formula, x ₁ and x ₂ are integers of 1 to 5, respectively. (a) (a-1) a first monomer unit having a protecting group of the following structure, Wherein R ₁ and R ₂ are each a hydrogen atom or fluorine, at least one of R ₁ and R ₂ is fluorine, and R ₃ is a C ₅ to C ₂₀ fluorine-substituted or unsubstituted ring hydrocarbon group. (a-2) Photosensitive polymer consisting of a polymerization product with at least one second monomer unit selected from the group consisting of acrylate monomers, methacrylate monomers, maleic anhydride monomers, norbornene monomers, tetrafluoroethylene and sulfur dioxide Wow, (b) A resist composition comprising PAG. 10. The resist composition of claim 9, wherein the photosensitive polymer comprises a repeating unit of the following structure. The resist composition of claim 10, wherein the photosensitive polymer comprises the following structure. 10. The resist composition of claim 9, wherein the photosensitive polymer comprises a repeating unit of the following structure. The resist composition of claim 12, wherein the photosensitive polymer comprises the following structure. The resist composition of claim 12, wherein the photosensitive polymer comprises the following structure. Wherein R ₄ is a hydrogen atom, -CH ₃ or -CF ₃ . The resist composition according to any one of claims 9 to 14, wherein R ₃ has any one structure selected from the following structures. In the formula, x ₁ and x ₂ are integers of 1 to 5, respectively. The resist composition according to claim 9, wherein the weight average molecular weight of the photosensitive polymer is 2,000 to 100,000. The resist composition of claim 9, wherein the PAG is included in an amount of 1 to 15 wt% based on the weight of the photosensitive polymer. 10. The resist composition of claim 9, wherein the PAG consists of triarylsulfonium salts, diaryliodonium salts, sulfonates or mixtures thereof. 10. The resist composition of claim 9, further comprising an organic base. The resist composition of claim 19, wherein the organic base is included in an amount of 0.01 to 2.0 wt% based on the weight of the photosensitive polymer.