KR20050034839A - Carbon nanotube-graft-siloxane polymer and process for preparing dielectric film using the same - Google Patents

Abstract

The present invention relates to a carbon nanotube-graft-siloxane polymer obtained by reacting an acid treated carbon nanotube with a siloxane polymer containing a functional group capable of polycondensation using a condensation reaction agent, and The present invention relates to a method of forming an insulating film by dispersing it in an organic solvent or an organic solution of a polymer, and then applying it on a substrate to dry the insulating film. It is excellent and maintains low dielectric constant.

Description

Carbon Nanotube-Graft-Siloxane Polymer and Process for Preparing Dielectric Film using the Same}

The present invention relates to a carbon nanotube-graft-siloxane polymer and a method for preparing an insulating film using the same, and more particularly, to reacting an acid-treated carbon nanotube with a siloxane polymer containing a functional group capable of condensation polymerization using a condensation reagent. CNT-graft-siloxane polymer obtained by dispersing and dispersing the polymer in an organic solvent or an organic solution of a polymer, coated on a substrate and dried to form a semiconductor interlayer insulating film It is about.

As the degree of integration of semiconductors increases, a problem of decreasing signal transmission speed due to an increase in RC delay of a wiring structure becomes serious. Therefore, lowering capacitance of an interlayer insulating thin film becomes an important issue in semiconductor devices. To this end, US Pat. Nos. 3,615,272, 4,399,266, 4,756,977, and 4,999,397 are manufactured by spin on deposition (SOD) instead of SiO ₂ (dielectric constant 4.0) insulating films that require chemical vapor deposition (Chemical Vapor Deposition). A polysilsesquioxane (a dielectric constant of about 2.5 to 3.1) that can be used is disclosed. Hydrogen silsesquioxanes and various methods for their preparation are known in the art. For example, US Pat. No. 3,615,272 discloses a process for producing hydrogen silsesquioxane in a fully condensed state by condensing trichloro, trimethoxy, triacetoxy silane in a sulfuric acid medium. . U.S. Pat.No. 5,010,159 discloses a process for producing hydrogen silsesquioxane by hydrolyzing hydrosilane in a hydrolysis medium containing arylsulfonic acid hydrate to form a resin, and then contacting the resin with a neutralizing agent. have. In addition, U. S. Patent No. 6,232, 424 discloses stable and soluble silicones in solution by hydrolyzing and condensing tetraalkoxysilane, organosilane and organotrialkoxysilane in the presence of water and a catalyst. A resin resin composition and a method of preparing the same are disclosed. US Patent No. 6,000,339 discloses a method for preparing a silica-based compound having improved resistance to oxygen plasma and other physical properties and capable of forming a thin film. The method includes an alkoxysilane and an alkoxysilane containing fluorine. and a monomer selected from fluorine-containing alkoxysilane and alkylalkoxysilane and a titanium or zirconium alkoxide compound under water and a catalyst. U.S. Patent No. 5,853,808 discloses siloxane and silsesquioxane prepared by using a compound in which a reactive group is substituted at the β position of an organosilane to increase the SiO ₂ content of the thin film. A polymer and a thin film composition using the same are disclosed. EP 0 997 497 A1 also discloses monoalkoxysilanes, dialkoxysilanes, trialkoxysilanes, tetraalkoxysilanes and trialkoxysilane dimers. A composition obtained by hydrolyzing and condensing a mixture of various alkoxysilane compounds and a thin film insulating film using the same are disclosed. In addition, U.S. Patent No. 5,378,790 discloses organic / organic hybrid materials having excellent physical properties, and Korean Patent No. 343938 discloses siloxane resins prepared by hydrolysis and condensation reaction of cyclic siloxane monomers, and A thin film insulating thin film using the same is disclosed. However, the insulating film using the siloxane polymer prepared by all the above known techniques does not provide a sufficiently low dielectric constant, or even if it provides a sufficiently low dielectric constant, the mechanical properties of the film are not good, and the organic carbon content in the insulating film is high. There is a problem. Accordingly, there is a need in the art for the development of an insulating film forming material having a low insulation coefficient and excellent mechanical properties such as toughness as an insulating film that can be produced by SOD.

On the other hand, since the discovery of Dr. Ijima in 1991, many researches have been conducted as nano-sized materials have a cylindrical structure having a diameter of about 1 to 20 nm, usually made of graphite. The graphite surface of the carbon nanotubes has a unique bond arrangement of a strong, flat hexagonal plate-like membrane structure, forms a tube wound in a spiral shape, has a bond of edges at different points, and the upper and lower portions of the film are filled with free electrons. The free electrons move in parallel with the film in discrete states. The electrical properties of nanotubes are known to be a function of structure and diameter [ Phys. Rev. B46, 1804 (1992); Phys. Rev. Lett. 68, 1579 (1992)], depending on the structure and the difference in diameter can represent from the insulator to the semiconductor and metallic. For example, changing the helical or chirality of carbon nanotubes changes the way of free electron movement, and the movement of free electrons is completely free and the carbon nanotubes have the same conductive properties as metals, or The presence of barriers to be overcome may also indicate the characteristics of the semiconductor. At this time, the size of the barrier is determined according to the diameter of the tube, it is known that even 1eV at the minimum diameter.

Carbon nanotubes are excellent in mechanical properties such as flat panel display devices, transistors, and energy storage materials because of their excellent mechanical robustness and chemical stability, their ability to exhibit both semiconductor and conductor properties, and their small diameter, length, and hollowness. It shows properties, and its applicability as nano-sized various electronic devices is very large.

The present inventors have diligently studied to solve the above problems, and after introducing a carboxylate group on the surface of the carbon nanotubes, reacting them with the end groups of the siloxane polymers, the carbon nanotube-graft-siloxane polymers (CNT-graft- siloxane polymer), and when it is used to manufacture a semiconductor interlayer insulating film, the mechanical properties are remarkably improved, thereby completing the present invention.

That is, one aspect of the present invention relates to a carbon nanotube-graft-siloxane polymer obtained by reacting an acid treated carbon nanotube in an organic solvent with a siloxane polymer containing a functional group capable of condensation polymerization using a condensation reaction agent. .

Another aspect of the present invention relates to a method for forming a semiconductor interlayer insulating film comprising the step of dispersing the carbon nanotube-graft-siloxane polymer in a solvent to prepare a dispersion, applying it to a substrate, and then thermally curing.

Another aspect of the present invention relates to a semiconductor interlayer insulating film prepared by dispersing the carbon nanotube-graft-siloxane polymer in a solvent to prepare a dispersion, applying it to a substrate, and then thermally curing it.

Hereinafter, the present invention will be described in more detail.

The carbon nanotubes used in the present invention are not particularly limited as long as the object of the present invention is not impaired, and commercially available products can be purchased. For example, a conventional arc discharge method, laser ablation, high temperature filament plasma chemical vapor deposition, microwave plasma chemical vapor deposition, thermochemical vapor deposition, or pyrolysis can be used. However, since the carbon nanotubes synthesized by the above method include carbon-containing materials such as by-products amorphous carbon and fullerene, and transition metals used as catalysts for growth of the tubes, a separate Purification process is required. Purification of the carbon nanotubes can be used in all methods known in the art, preferably according to the method described below, but is not limited thereto. First, the carbon nanotubes are refluxed in distilled water at 100 ° C. for 8 to 24 hours, preferably 12 hours, and then filtered to completely dry the filtrate, followed by washing the dried powder with toluene to obtain Remove the same carbon-containing materials. The soot obtained therefrom is then heated at a temperature of 450 to 500 ° C, preferably 470 ° C. The heating time is suitable for 20 to 30 minutes, preferably 20 minutes, and finally, 4 to 7M, preferably about 6M may be washed with hydrochloric acid to remove all metallic contaminants to obtain pure carbon nanotubes.

The carbon nanotubes undergoing the purification process as described above introduce carboxyl groups on their surfaces by acid treatment. The acid treatment may be any known method as long as it can introduce a carboxylate group to the surface of the carbon nanotubes, but preferably, a method of introducing a carboxylate group to the surface of the carbon nanotubes by treating with a reflux strong acid I use it. At this time, the strong acid is preferably nitric acid, sulfuric acid or a mixed solution thereof, but is not limited thereto.

First, the carbon nanotubes are refluxed for 72 to 120 hours in a mixed acid solution of nitric acid and sulfuric acid at a volume ratio of 1: 9 to 9: 1, preferably 2: 8 to 8: 2, and preferably 0.1 to 0.4 mu m. After filtration with a 0.2 μm polycarbonate filter, the filtrate was immersed in nitric acid again and refluxed at 90 to 120 ° C. for 45 to 60 hours, followed by centrifugation. After centrifugation, the supernatant is recovered, filtered through a polycarbonate filter, the filtrate is completely dried, and filtered through a polycarbonate filter to screen only carbon nanotubes having a certain size. Carboxylation of the obtained carbon nanotubes can be confirmed by Raman spectrum, etc., and in the case of acid treated carbon nanotubes, they exist as a uniform slurry having a constant viscosity because of the carboxyl groups present on the surface.

The acid treated carbon nanotubes form a random network, and a plurality of carboxylate groups are present on the surface thereof to form coulomb force upon reaction with the siloxane polymer.

The siloxane polymer to react with the acid treated carbon nanotubes is not particularly limited and any known siloxane polymer may be used.

More specifically, at least one monomer selected from the group consisting of silane monomers, cyclic siloxane monomers and cage siloxane monomers can be obtained by condensation reaction in the presence of water with an acid or base catalyst in an organic solvent.

The silane monomers include, but are not limited to, materials represented by the following Chemical Formulas 1 to 2 specifically.

R _1n Si (OR ₂ ) _4-n

Wherein R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , an aryl group or a halogen atom of C ₆ to C ₁₅ , and at least one of R ₁ and R ₂ is a hydrolyzable functional group and n is an integer of 0-3.

X _One X ₂ X ₃ Si-M-SiX _One X ₂ X ₃

In the above formula, M is C ₆ ~ C ₁₅ An arylene group or a C ₁ to C ₁₀ alkylene group, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an C ₁ to C ₃ alkyl group, a C ₁ to C ₁₀ alkoxy group or a halogen atom, At least one of ₁ , X ₂ and X ₃ is a hydrolyzable functional group.

The cyclic siloxane monomers include, but are not limited to, a material represented by the following Chemical Formula 3 or 4.

Wherein R ₁ is a hydrogen atom, an alkyl group of C ₁ to C ₃ or an aryl group of C ₆ to C ₁₅ , X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , As an alkoxy group or halogen atom of C ₁ to C ₁₀ , at least one of X ₁ , X ₂ and X ₃ is a hydrolyzable functional group, p is an integer of 3 to 8, and m is an integer of 0 to 10.

Wherein R ₁ is a hydrogen atom, an alkyl group of C ₁ to C ₃ or an aryl group of C ₆ to C ₁₅ , and R ₂ is a hydrogen atom, an alkyl group of C ₁ to C ₃ , R'CO or SiX ₁ X ₂ X ₃ , wherein R 'is an alkyl group having 1 to 3 carbon atoms, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , an alkoxy group of C ₁ to C ₁₀ or a halogen atom At least one of X ₁ , X ₂ and X ₃ is a hydrolyzable functional group, and p is an integer of 3 to 8.

In addition, the cage-type siloxane monomers include, but are not limited to, a material represented by the following Chemical Formulas 5 to 7.

In Formulas 5 to 7, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ ~ C ₃ , an alkoxy group of C ₁ ~ C ₁₀ or a halogen atom, X ₁ , X ₂ and X At least one of ₃ is a hydrolyzable functional group and n is an integer of 0-10.

The acid or base catalyst used in the preparation of the siloxane polymer may be hydrochloric acid, nitric acid, benzene sulfonic acid, oxalic acid, formic acid, or potassium hydroxide. hydroxide, sodium hydroxide, triethylamine, sodium bicarbonate, pyridine and the like can be used, but is not limited thereto. The catalyst is used in a range in which the molar ratio of the catalyst to the monomer is 1: 0.00001 to 1:10.

The water used in the hydrolysis and condensation reaction is used in a range in which the molar ratio of water to monomers is 1: 1 to 1: 100.

In addition, in the preparation of the siloxane polymer, an aromatic solvent containing an aliphatic hydrocarbon solvent such as hexane, anisole, mesitylene and xylene is used as an organic solvent. ); Ketone-based solvents including methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, 1-methyl-2-pyrrolidinone, cyclohexanone and acetone solvent); Ether-based solvents including tetrahydrofuran and isopropyl ether; Acetate-based solvents including ethyl acetate, butyl acetate and propylene glycol methyl ether acetate; Alcohol-based solvents including isopropyl alcohol and butyl alcohol; Amide solvents including dimethylacetamide and dimethylformamide; Silicon-based solvents; Or a mixture of one or more of them.

In the condensation reaction, the temperature is in the range of 0 to 200 ° C, and the reaction time is preferably 0.1 to 100 hours.

The siloxane polymer prepared above preferably has a molecular weight in the range of 3,000 to 300,000, and preferably has a Si-OH content of 5% or more in the terminal groups of the entire polymer.

The siloxane polymer obtained as described above is reacted with carbon nanotubes using a condensation reaction agent in an organic solvent, and the hydroxy reactor present in a plurality of carboxylate groups and siloxane polymer terminal groups on the surface of the acid-treated carbon nanoparticles By condensation reaction, a carbon nanotube-graft-siloxane polymer is obtained.

Examples of the condensation reaction agent that can be used in the condensation reaction include 1,3-dicyclohexylcarbodimide (DCC), N, N-diisopropylethylamine (DIEA), O- (7-Azabenzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate [O- (7-Azabenzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate: HATU] or a mixture of two or more thereof, but is not limited thereto.

The amount of carbon nanotubes used in the reaction is preferably 0.001 to 10 parts by weight based on 100 parts by weight of the siloxane polymer.

The organic solvent used in the condensation reaction is not particularly limited, but dimethyl formamide (DMF) is preferably used.

The carbon nanotube-graft-siloxane polymer according to the present invention may be dispersed in an organic solvent or an organic solution of a polymer, and then coated on a substrate and thermoset to prepare an insulating film. When the carbon nanotube-graft-siloxane polymer is dispersed in an organic solvent or an organic solution of a polymer, dispersion is easily performed, and compatibility is greatly improved by the coulomb force formed at the interface between the siloxane polymer and the carbon nanotube. There is no problem that the siloxane polymer and the carbon nanotubes are phase separated or precipitated over time during coating without using an active agent.

The organic solvent is not particularly limited, but is preferably an aliphatic hydrocarbon solvent such as hexane or heptane; Aromatic hydrocarbon solvents such as anisol, mesitylene and xylene; Ketone-based solvents such as methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, 1-methyl-2-pyrrolidinone, cyclohexanone, and acetone ); Ether-based solvents such as tetrahydrofuran and isopropyl ether; Acetate-based solvents such as ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate; Isopropyl alcohol, butyl alcohol, alcohol-based solvents; Amide solvents such as dimethylacetamide and dimethylformamide; Silicon-based solvents; Or mixtures thereof.

The content of the solvent is preferably 20 to 99.9 wt% based on the total composition.

As described above, the dispersion formed by dispersing the carbon nanotube-graft-siloxane polymer in an organic solvent or an organic solution of a polymer may further include a pore-forming material within a range that does not impair the object of the present invention to form a coating solution. The coating solution is coated on a substrate and thermally cured to prepare an insulating film.

The pore forming material includes all known pore forming materials used for forming a porous insulating film. Preferably, a compound selected from the group consisting of cyclodextrin and derivatives thereof, polycaprolactone and derivatives thereof may be used alone or in combination of two or more thereof. The pore-forming material is preferably present in an amount of 0 to 70% by weight based on the total weight of solids (ie, carbon nanotube-graft-siloxane polymer and pore-forming material) in the coating solution.

The substrate is not particularly limited as long as the object of the present invention is not impaired, and any substrate capable of withstanding thermosetting conditions, for example, a glass substrate, a silicon wafer, or a plastic substrate may be selected and used depending on the application.

Methods of applying the coating solution include spin coating, dip coating, spray coating, flow coating, and screen printing, but are not limited thereto. It doesn't work. Spin coating is most preferred in view of convenience and uniformity. When spin coating is performed, the spin speed is preferably adjusted within the range of 800 to 5,000 rpm.

After the coating is completed on the substrate, a process of drying the film by evaporating the solvent as necessary so that a film made of a carbon nanotube-graft-siloxane polymer and optionally a pore-forming material is formed. The film drying process can be carried out simply by exposing to the ambient environment, applying a vacuum in the initial stages of the curing process, or by slightly heating to a temperature below 200 ° C.

The film is then thermoset at a temperature of 150 ° C. to 600 ° C., preferably 200 ° C. to 450 ° C. for 1 to 150 minutes to form an insoluble coating free of cracks. A crack-free film is a film in which no visible crack is observed when viewed with an optical microscope at a 1000x magnification. An insoluble film is used to apply a solvent or resin to form a film by depositing a siloxane-based polymer. It refers to a coating that is essentially insoluble in a solvent described as useful.

An insulating film composed of carbon nanotube-graft-siloxane polymer only has a dielectric constant of 3.0 or less and can be used as a low dielectric coating film between semiconductor layers, and the insulating film formed by including a pore-forming material in the carbon nanotube-graft-siloxane polymer is It has a dielectric constant of 2.5 or less.

In the case of the insulating film prepared by the method according to the present invention, due to the excellent compatibility between the acid-treated carbon nanotubes and the siloxane polymer, a structure in which the carbon nanotubes are doped in a random network structure of the siloxane polymer Since the dielectric constant and carbon content of the insulating film obtained by the insulating material while maintaining a large specific surface area, even a small amount of addition can dramatically improve the mechanical properties of the film.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

The measuring method for measuring the performance of the insulating film prepared in the following Examples will be described first.

1) permittivity measurement

3000Å of silicon thermal oxide was deposited on boron-doped p-type silicon wafer, and 100Å of titanium, 2000Å of aluminum thin film, and 100Å of titanium were deposited using a metal evaporator. Then, an insulating film to be measured was formed thereon. Using a hard mask designed with an electrode diameter of 1 mm on the insulating film, a circular titanium 100 Å and an aluminum thin film 5000 Å having a diameter of 1 mm were deposited to form a metal-insulator-metal (MIM) structure. A low dielectric thin film for measuring dielectric constant is completed. Measure the capacitance at frequencies of about 10 kHz, 100 kHz, and 1 MHz using a PRECISION LCR METER (HP4284A) equipped with a probe station (micromanipulatior 6200 probe station) and thin film thickness using a prism coupler. The dielectric constant is then calculated from the following equation:

k = C xd / ε ₀ x A

(Where k is the relative permittivity, C is the capacitance, ε ₀ is the dielectric constant of vacuum, d is the thickness of the insulating film, and A is the contact cross-sectional area of the electrode).

2) hardness and modulus

Hardness and modulus of elasticity were determined by quantitatively analyzing the insulating film using MTS Nanoindenter II. More specifically, the thin film was indented with a nanoindenter, and the hardness and modulus of the thin film were obtained when the indentation depth was 10% of the thin film thickness. The thickness of the thin film was measured using a prism coupler. In the present Example and the comparative example, in order to ensure the reliability, nine points on the insulating film were press-fitted and the hardness and elastic modulus were calculated from the average value.

3) carbon content

X-ray photoelectron spectroscopy (XPS) is used to measure the carbon content of the insulating film. The device used in the present Examples and Comparative Examples was used was a model Q2000's Physical Electronics, solid sex (monochromatic) Al source (1486.6 eV ) in X-ray generator. Specifically, sputtering the thin film with 3 keV ar ion and performing element determination according to the depth, and the quantitative value averaged in a certain section in which the content of each element of the thin film is kept constant is carbon content. It was.

Preparation Example 1

Preparation of siloxane polymer A

Methyl trimethoxysilane (MTMS) was put in a flask, tetrahydrofuran was added and diluted so that the total solution concentration might be 0.05-0.07M, and the reaction liquid temperature was -78 degreeC. After adding hydrochloric acid and water in an amount as shown in Table 1, respectively, the temperature of the reaction solution was gradually raised from -78 ° C to 70 ° C, and the reaction was carried out for 16 hours. After the reaction solution was transferred to a separatory funnel, the same amount of tetraethylfuran and tetrahydrofuran in the same amount were added, washed three times with about 1/10 of the total solvent, and then the volatiles were removed under reduced pressure. Removal to obtain a polymer in the form of a white powder. The polymer obtained by the above method was dissolved in acetone to form a transparent solution, which was then filtered through a filter having a pore of 0.2 μm, and water was slowly added to the filtrate to obtain a precipitate of white powder. The white powder was dried at 0-20 ° C. under 0.1 Torr for 10 hours to obtain a fractionated siloxane polymer. The amount of monomer, acid catalyst, water and siloxane polymer used in each polymer synthesis, and the molecular weight, Si-OH content, Si-OCH ₃ content, and Si-CH ₃ content of the prepared polymer are shown in Table 1 below. It was. However, the content of the Si-OH, Si-OCH ₃ and Si-CH ₃ was analyzed by a nuclear magnetic resonance analyzer (NMR, Bruker) according to the following formula.

Si-OH (%) = Area (Si-OH) ÷ [Area (Si-OH) + Area (Si-OCH ₃ ) / 3 + Area (Si-CH ₃ ) / 3] × 100

Si-OCH ₃ (%) = Area (Si-OCH ₃ ) / 3 ÷ [Area (Si-OH) + Area (Si-OCH ₃ ) / 3 + Area (Si-CH ₃ ) / 3] × 100

Si-CH ₃ (%) = Area (Si-CH ₃ ) / 3 ÷ [Area (Si-OH) + Area (Si-OCH ₃ ) / 3 + Area (Si-CH ₃ ) / 3] × 100

Preparation Example 2

Siloxane polymer B

1,3,5,7-tetramethyl-1,3,5,7-cyclotetrasilaneol (1,3,5,7) represented by the following formula (8) instead of methyl trimethoxysilane (MTMS) -Tetramethyl-1,3,5,7-cyclotetrasilanol: TS-T4 (OH)) and the TCS-2 represented by the following formula 9 was carried out in the same manner as in the polymer A. The molecular weight, Si-OH content, Si-OCH ₃ content, and Si-CH ₃ content of the prepared polymers are shown in Table 1 below. However, the Si-OH, Si-OCH ₃ and Si-CH ₃ content was analyzed by a nuclear magnetic resonance analyzer (NMR, Bruker) according to the above formula.

polymer Monomer type (mmol) HCl (mmol) H ₂ O (mmol) Polymer amount (g) Si-OH (g) Si-OCH ₃ (g) Si-CH ₃ (%) Preparation Example 1 A MTMS 1.664 0.166 5.20 27.25 1.25 71.50 73.41 Preparation Example 2 B TS-T4 TCS-2 0.028 0.077 3.80 28.14 0.95 70.91 20.69 2.28

Preparation Example 3

Purification and Carboxylation of Carbon Nanotubes

100 mg of carbon nanotubes (trade name ILJIN CNT AP-Grade, Iljin Nanotech, Korea) were refluxed at 100 ° C. for 12 hours using 50 ml of distilled water in a 500 ml flask equipped with a reflux tube. After refluxing, the material filtered through the filter was dried at 60 ° C. for 12 hours, and then the residual fullerene was washed with toluene. The remaining soot material was recovered from the flask and heated in a 470 ° C. heating furnace for 20 minutes, and finally washed with 6M hydrochloric acid to remove all metal components to obtain pure carbon nanotubes.

The purified carbon nanotubes were refluxed in a sonicator containing a mixed acid solution having a ratio of nitric acid to sulfuric acid 7: 3 (v / v) for 96 hours, filtered through a 0.2 μm polycarbonate filter, and the filtrate was again filtered. The supernatant obtained by immersion in nitric acid and refluxed at 90 ° C. for 45 hours and then centrifuged at 12,000 rpm was filtered through a 0.1 μm polycarbonate filter and dried at 60 ° C. for 12 hours. The dried carbon nanotubes were dispersed in DMF, and filtered again using a 0.1 μm polycarbonate filter.

Examples 1 and 2

Grafting of Carbon Nanotubes

5 g each of the siloxane polymers A and B obtained in Preparation Examples 1 and 2 and 0.01 g of the acid treated carbon nanotubes obtained in Preparation Example 3 were mixed in 250 ml of dimethylformamide and condensed in a composition as shown in Table 2 below. After 12 hours of condensation reaction using a reactant, the unreacted product was washed several times with methanol. The precipitate was filtered through a 0.2 μm polycarbonate filter and dried at 40 ° C. for 12 hours to obtain a carbon nanotube-graft-siloxane polymer.

Siloxane polymer Acid Treated Carbon Nanotubes A condensation reagent Example 1 Polymer A 5g 0.01 g DCC / DIEA (2.5g / 1.2g) Example 2 Polymer B 5g 0.01 g DCC / DIEA (2.5g / 1.2g)

Examples 3 and 4

Preparation of Insulation Film

The carbon nanotube-graft-siloxane polymers obtained in Examples 1 and 2 were prepared using propylene glycol methyl ether acetate as a solvent. In the coating liquid, the solid content was 30% by weight. The coating solution was spin-coated on a silicon wafer for 30 seconds at 3000 rpm, and preheated at 150 ° C. for 1 minute and at 250 ° C. for 1 minute on a hot plate in a nitrogen atmosphere to prepare a film. The film was fired at 420 ° C. (heating rate: 3 ° C./min) for 1 hour in a vacuum atmosphere to prepare an insulating film. The thickness, refractive index, dielectric constant, hardness, modulus, and carbon content of the prepared insulating film were measured and the results are shown in Table 3. In the following table, the dielectric constant is measured at 100 kHz.

Comparative Examples 1 and 2

After the siloxane polymers A and B obtained in Production Examples 1 and 2 were formed in the same manner as in Examples 3 to 4, respectively, the thickness, refractive index, dielectric constant, and hardness were measured. , Modulus, and carbon content were measured and compared with the insulating films prepared in Examples 3 to 4, and the results are shown in Table 3.

Composition of Coating Liquid Refractive index Thickness permittivity Longitude (GPa) Modulus of elasticity (GPa) Carbon content (%) Comparative Example 1 Polymer A 1.373 13580 2.90 0.34 2.62 19.8 Example 3 CNT-g-polymer A 1.375 16890 2.91 0.40 2.63 20.2 Comparative Example 2 Polymer B 1.412 10360 2.70 1.05 6.76 25.4 Example 4 CNT-g-polymer B 1.413 12570 2.72 1.15 6.76 25.8

As shown in Table 3, in the case of the insulating film obtained by the method according to the present invention, by adding a small amount of carbon nanotubes have a higher mechanical properties than conventional materials, from the above results It can be seen that the nanotubes are doped with chemical linkages, increasing the mechanical properties of the coated film.

The insulating film according to the present invention is excellent in compatibility with the pore-forming material, and the mechanical properties of the carbon content and the dielectric constant is significantly increased, so that it can be usefully used in the field of semiconductor devices.

Claims (12)

A carbon nanotube-graft-siloxane polymer obtained by reacting an acid treated carbon nanotube with a siloxane polymer containing a functional group capable of condensation polymerization under an organic solvent. The siloxane polymer according to claim 1, wherein the siloxane polymer containing a polycondensable functional group is a silane monomer represented by Formulas 1 and 2, a cyclic siloxane monomer represented by Formulas 3 and 4, and a cage type represented by Formulas 5 to 7. A carbon nanotube-graft-siloxane polymer, which is prepared by condensation polymerization and hydrolysis of at least one monomer selected from the group consisting of siloxane monomers in an organic solvent in the presence of an acid or a base catalyst and water: [Formula 1] R _1n Si (OR ₂ ) _4-n Wherein R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , an aryl group or a halogen atom of C ₆ to C ₁₅ , and at least one of R ₁ and R ₂ is a hydrolyzable functional group and n is an integer of 0-3. [Formula 2] X ₁ X ₂ X ₃ Si-M-SiX ₁ X ₂ X ₃ In the above formula, M is C ₆ ~ C ₁₅ An arylene group or a C ₁ to C ₁₀ alkylene group, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an C ₁ to C ₃ alkyl group, a C ₁ to C ₁₀ alkoxy group or a halogen atom, At least one of ₁ , X ₂ and X ₃ is a hydrolyzable functional group. [Formula 3] Wherein R ₁ is a hydrogen atom, an alkyl group of C ₁ to C ₃ or an aryl group of C ₆ to C ₁₅ , X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , As an alkoxy group or halogen atom of C ₁ to C ₁₀ , at least one of X ₁ , X ₂ and X ₃ is a hydrolyzable functional group, p is an integer of 3 to 8, and m is an integer of 0 to 10. [Formula 4] Wherein R ₁ is a hydrogen atom, an alkyl group of C ₁ to C ₃ or an aryl group of C ₆ to C ₁₅ , and R ₂ is a hydrogen atom, an alkyl group of C ₁ to C ₃ , R'CO or SiX ₁ X ₂ X ₃ , wherein R 'is an alkyl group having 1 to 3 carbon atoms, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ to C ₃ , an alkoxy group of C ₁ to C ₁₀ or a halogen atom At least one of X ₁ , X ₂ and X ₃ is a hydrolyzable functional group, and p is an integer of 3 to 8. [Formula 5] [Formula 6] [Formula 7] In Formulas 5 to 7, X ₁ , X ₂ and X ₃ are each independently a hydrogen atom, an alkyl group of C ₁ ~ C ₃ , an alkoxy group of C ₁ ~ C ₁₀ or a halogen atom, X ₁ , X ₂ and X At least one of ₃ is a hydrolyzable functional group and n is an integer of 0-10. The method of claim 1, wherein the organic solvent is a hydrocarbon solvent (aliphatic hydrocarbon solvent); Aromatic hydrocarbon solvents; Ketone-based solvents; Ether-based solvents; Acetate-based solvents; Alcohol-based solvents; Amide solvents; Silicon-based solvents; Or a mixture of these, carbon nanotube-graft-siloxane polymer. The carbon nanotube-graft-siloxane polymer according to claim 1, wherein acid-treated carbon nanotubes are used in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of the siloxane polymer. The method of claim 1, wherein the condensation reaction agent is 1,3-Dicyclohexylcarbodimide (DCC), N, N-diisopropylethylamine (DIEA), O- (7-Azabenzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate [O- (7-Azabenzotriazol-1-yl) -N, N, N' , N'-tetramethyluronium hexafluorophosphate: HATU] or a mixture of two or more thereof, carbon nanotube-graft-siloxane polymer. A method for forming a semiconductor interlayer insulating film comprising the step of dispersing the carbon nanotube-graft-siloxane polymer of claim 1 in a solvent to prepare a dispersion, applying the same to a substrate, and then performing thermal curing. The method of claim 6, wherein the solvent is aliphatic hydrocarbon solvent (aliphatic hydrocarbon solvent); Aromatic hydrocarbon solvents; Ketone-based solvents; Ether-based solvents; Ethyl acetate, acetate-based solvents; Alcohol-based solvents; Amide solvents; Silicon-based solvents; Or a mixture thereof. 7. The method of claim 6, wherein the content of the solvent in the dispersion is 20 to 99.9% by weight. The method of claim 6, wherein a pore-forming material is further added to the dispersion. 10. The method for forming a semiconductor interlayer insulating film according to claim 9, wherein cyclodextrin and derivatives thereof, polycaprolactone or derivatives thereof are used as the pore forming material. 10. The method of claim 9, wherein the pore-forming material is formed in a content of 0 to 70% by weight based on the solids content of the dispersion (carbon nanotube-graft-silonic acid polymer + pore-forming material). Way. A semiconductor interlayer insulating film prepared by dispersing the carbon nanotube-graft-siloxane polymer of claim 1 in a solvent to prepare a dispersion, applying the same to a substrate, and then performing thermal curing.