JP2012104616A - Precursor composition of low dielectric constant film and method for manufacturing low dielectric constant film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precursor composition of a low dielectric constant film used for manufacturing a low dielectric constant film that is suppressed in degradation of hydrophobic properties even through being irradiated with UV and is suppressed in increase of a dielectric constant, and a method for manufacturing the low dielectric constant film.SOLUTION: A precursor composition of a low dielectric constant film comprises at least one compound selected from the groups consisting of diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane; at least one substance selected from the groups consisting of compounds represented by Formula: (RO)-Si-X-Si-(RO)(wherein RO is alkoxy and X is an organic crosslinking group selected from the groups consisting of methylene, ethylene, vinylene and 1,4-phenylene), compounds represented by Formula: Si(OR)(wherein R is a univalent organic group), cyclic siloxanes, double cyclic siloxanes and zeolite crystallite; a pyrolytic compound; and an alkoxysilane hydrolytic catalyst.

Description

  The present invention relates to a precursor composition for a low dielectric constant film and a method for producing a low dielectric constant film using the same.

  A plurality of interlayer insulating films are formed on the LSI multilayer wiring. Since a sufficient reduction in the electric capacity between the wirings is required, a low dielectric constant film having a relative dielectric constant of 3.9 or less is generally used as this interlayer insulating film. Further, the interlayer insulating film is required to have high hydrophobicity. This is because the dielectric constant increases when water is absorbed.

  As a low dielectric constant film that can be used as an interlayer insulating film, a porous silica film in which a plurality of pores are formed has been developed (for example, Patent Document 1 and Non-Patent Document 1).

  In the method for producing a porous film disclosed in Patent Document 1, first, a predetermined precursor composition containing a silica source and a thermally decomposable organic compound is prepared. This precursor composition is formed into a film on a substrate, and a pyrolytic organic compound is pyrolyzed by firing to produce a porous film. And the porous membrane which has hydrophobicity is obtained by carrying out the gas phase reaction of the hydrophobic compound to the produced porous membrane, and modifying the surface of a void | hole.

  Moreover, the manufacturing method of the low dielectric constant film disclosed in Non-Patent Document 1 discloses a manufacturing method of the low dielectric constant film including a hydrophobic treatment process. In this method, the hydrophobization treatment is performed using hexamethyldisilazane or the like.

JP 2006-265350 A

Japan Journal of Applied Physics, 47, 2008, 8364

  The method for producing a porous film disclosed in Patent Document 1 requires a step of modifying a hydrophobic compound by a gas phase reaction, which complicates the manufacturing process and increases the manufacturing cost.

  In addition, in the method for producing a low dielectric constant film disclosed in Non-Patent Document 1, the precursor composition is applied in a film shape on a substrate and baked, followed by a hydrophobic treatment. In addition to high production costs, it is difficult to obtain sufficient hydrophobicity.

  The present invention has been made in view of the above matters, and an object of the present invention is to produce a low dielectric constant film in which a decrease in hydrophobicity is suppressed even when irradiated with ultraviolet rays, and an increase in dielectric constant is suppressed. An object of the present invention is to provide a precursor composition for a low dielectric constant film and a method for producing a low dielectric constant film using the same.

The low dielectric constant film precursor composition according to the first aspect of the present invention comprises:
One or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane;
Formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group, and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group. ), A compound represented by the formula: Si (OR) ₄ (R is a monovalent organic group), one or more substances selected from cyclic siloxane, bicyclic siloxane and zeolite microcrystals,
A thermally decomposable compound;
And an alkoxysilane hydrolysis catalyst.

The low dielectric constant film precursor composition according to the second aspect of the present invention comprises:
Diethoxymethylsilane,
Tetraethoxysilane,
A thermally decomposable compound;
An alkoxysilane hydrolysis catalyst;
Containing.

A method for producing a low dielectric constant film according to a third aspect of the present invention is as follows:
One or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane, and dimethylmethoxysilane, and a formula: (RO) ₃ —Si— A compound represented by the formula: X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group), a formula: One or more substances selected from a compound represented by Si (OR) ₄ (R is a monovalent organic group), cyclic siloxane, bicyclic siloxane, and zeolite microcrystal; a thermally decomposable compound; Preparing a precursor composition comprising a cracking catalyst;
A film forming step of forming the precursor composition on a substrate;
A drying step of drying the film obtained in the film forming step;
A firing step of firing the film obtained in the drying step;
An ultraviolet treatment step of subjecting the film obtained in the baking step to an ultraviolet treatment.

The method for producing a low dielectric constant film according to the fourth aspect of the present invention includes:
Preparing a precursor composition comprising diethoxymethylsilane, tetraethoxysilane, a thermally decomposable compound, and an alkoxysilane hydrolysis catalyst;
A film forming step of forming the precursor composition on a substrate;
A drying step of drying the film obtained in the film forming step;
A firing step of firing the film obtained in the drying step;
An ultraviolet treatment step of subjecting the film obtained in the firing step to ultraviolet treatment;
Is provided.

  The low dielectric constant film precursor composition according to the present invention is selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane. Contains one or more compounds. When a low dielectric constant film is produced using this precursor composition, since the hydrophobization treatment is unnecessary, the low dielectric constant film can be produced easily with few production steps.

  Furthermore, since the obtained low dielectric constant film suppresses a decrease in hydrophobicity due to ultraviolet irradiation, an increase in dielectric constant is suppressed. For this reason, when this low dielectric constant film is used as an interlayer insulating film of a multilayer wiring LSI, the dielectric constant of the low dielectric constant film is kept low even if UV treatment is performed after the film formation. Have the advantage available.

2 is an infrared transmission spectrum of the low dielectric constant film manufactured in Example 1. FIG. It is a graph which shows the dielectric constant with respect to the ultraviolet irradiation time in the nitrogen atmosphere of the low dielectric constant film | membrane manufactured in Example 1, and in air. 6 is an infrared transmission spectrum of the low dielectric constant film produced in Example 2. FIG. It is a graph which shows the relative dielectric constant with respect to the ultraviolet irradiation time in the nitrogen atmosphere of the low dielectric constant film | membrane manufactured in Example 2, and in air. 6 is an infrared transmission spectrum of the low dielectric constant film produced in Example 3. FIG. It is a graph which shows the relative dielectric constant with respect to the ultraviolet irradiation time in the nitrogen atmosphere of the low dielectric constant film | membrane manufactured in Example 3, and in air. 2 is an infrared transmission spectrum of the low dielectric constant film produced in Reference Example 1. FIG. It is a graph which shows the dielectric constant with respect to the ultraviolet irradiation time in the nitrogen atmosphere of the low dielectric constant film | membrane manufactured in Reference Example 1, and in air.

  A low dielectric constant film precursor composition and a low dielectric constant film manufacturing method using the precursor composition according to the present embodiment will be described in detail. First, the precursor composition of the low dielectric constant film will be described.

The precursor composition of the low dielectric constant film is one or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane And the formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group. A compound represented by the formula: Si (OR) ₄ (R is a monovalent organic group), one or more substances selected from cyclic siloxanes, bicyclic siloxanes, and zeolite microcrystals And a pyrolyzable compound having a thermal decomposition temperature of 250 ° C. or higher, and an alkoxysilane hydrolysis catalyst, which are contained in a solvent. Construed, it is a mixed form.

Formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic bridging group, methylene group (—CH 2 —), ethylene group (—CH 2 CH 2 —), vinylene group ( -CHCH-), a compound represented by 1,4-phenylene group (-C6H4-)), a compound represented by Si (OR) ₄ , a cyclic siloxane, a bicyclic siloxane and zeolite microcrystals One or more materials selected are silica sources and are the primary raw materials for low dielectric constant films. The silica source is a raw material for the siloxane network that becomes the skeleton of the structure of the low dielectric constant film.

  One or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane are silylating agents. These silylating agents are silane compounds having an alkoxy group, and form a siloxane bond (Si—O—Si) with a silica source or other silylating agent molecules when the alkoxy group is released by hydrolysis. A large siloxane network is formed. Moreover, said silylating agent is equipped with Si-H bond in molecular structure.

  A thermally decomposable compound having a thermal decomposition temperature of 250 ° C. or higher is a surfactant. Examples of the surfactant include various compounds such as a compound having a long-chain alkyl group and a hydrophilic group, and a compound having a polyalkylene oxide structure. Specific examples include polyoxyethylene (10) cetyl ether. The surfactant is thermally decomposed and disappears by baking the film after forming the film using the precursor composition. A film having a porous structure is formed by the disappearance of the surfactant.

  In the precursor composition, a siloxane network surrounds the surfactant. A large number of these aggregate in a self-organized manner to form a porous silica film having a uniform pore diameter.

  The alkoxysilane hydrolysis catalyst is a catalyst that promotes the cleavage of the alkoxy group of the silylating agent. The alkoxysilane hydrolysis catalyst may be any as long as it can promote the cleavage of the alkoxy group. As a catalyst having such an action, either an acidic catalyst or a basic catalyst may be used. Examples of the acidic catalyst include inorganic acids such as hydrochloric acid and organic acids such as acetic acid.

  The solvent is not particularly limited as long as the silylating agent, the silica source, the surfactant, and the alkoxysilane hydrolysis catalyst described above can be dissolved. The monoalcohol solvent, polyhydric alcohol solvent, ketone solvent , Organic solvents such as ether solvents, ester solvents and nitrogen-containing solvents.

Next, a method for manufacturing a low dielectric constant film will be described. A method for producing a low dielectric constant film includes one or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane, and dimethylmethoxysilane, Formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group, and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group. ), A compound represented by the formula: Si (OR) ₄ (R is a monovalent organic group), one or more substances selected from cyclic siloxane, bicyclic siloxane and zeolite microcrystals, A precursor composition containing a thermally decomposable compound having a thermal decomposition temperature of 250 ° C. or higher and an alkoxysilane hydrolysis catalyst is prepared. And a step, a step of forming a precursor composition, and drying the film, and a step of firing the film, and the step of ultraviolet treatment the film.

(Precursor composition preparation step)
A silylating agent, a silica source, and an alkoxysilane hydrolysis catalyst are mixed with a solvent in a reaction vessel. Further, a surfactant dissolved in a solvent is prepared in another reaction vessel and mixed with the contents of the reaction vessel. The silylating agent is a silane compound having an alkoxy group, and when the alkoxy group is removed by hydrolysis, a siloxane bond (Si-O-Si) is formed with a silica source or other silylating agent molecule, thereby producing a large-scale siloxane. Form a network. In the precursor composition, it is considered that this siloxane polymer forms a large-sized structure by surrounding the surfactant and self-organizing.

  As the silylating agent, one or more compounds selected from the above-mentioned diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane are used.

As the silica source, the above-mentioned formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group, and a methylene group, an ethylene group, a vinylene group, 1,4- Selected from phenylene groups), one or more compounds selected from Si (OR) ₄ (R is a monovalent organic group), cyclic siloxanes, bicyclic siloxanes and zeolite microcrystals The substance is used.

  As the alkoxysilane hydrolysis catalyst, the above-described acidic catalyst or basic catalyst is used. For example, hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid (hydrogen fluoride), phosphoric acid, boric acid, hydrobromic acid, ammonium salt, nitrogen-containing compound, acetic acid and the like may be used.

  The solvent is used for the purpose of dissolving the above-mentioned material substance, and the above-described organic solvent is used.

  As the surfactant, the above-described compound having a long-chain alkyl group and a hydrophilic group, a compound having a polyalkylene oxide structure, or the like is used.

(Film formation process)
The precursor composition obtained in the above step is applied onto a substrate to form a film. The substrate is not particularly limited, and examples thereof include a silicon wafer. The coating method of the precursor composition is not particularly limited, and general methods such as a spin coating method, a casting method, and a dip coating method are used.

(Drying process)
After film formation, a drying process is performed to volatilize the solvent. Drying conditions and drying methods are not particularly limited as long as the solvent used can be volatilized and removed.

(Baking process)
The film formed in the above process is baked at a high temperature of 250 ° C. or higher. When the precursor composition is calcined, the surfactant is thermally decomposed and disappears while maintaining the structure of the siloxane network described above. A portion where the surfactant disappears becomes a pore. In this way, a porous film is formed.

(UV treatment process)
The film fired in the above process is subjected to an ultraviolet irradiation annealing treatment to promote the siloxane bond of the porous silica film, thereby increasing the mechanical strength.

  A low dielectric constant film is obtained through the above steps. The obtained low dielectric constant film has high hydrophobicity. That is, even when exposed to air containing moisture, the absorption of moisture is suppressed, so the change in relative permittivity is small. Further, the high hydrophobicity and low dielectric constant of the low dielectric constant film are not easily damaged by ultraviolet irradiation. That is, the above hydrophobicity is maintained at a high level even when the ultraviolet irradiation annealing treatment is performed. The reason is described below.

  The above silylating agent has Si—H groups in the molecular structure, and it is considered that many Si—H groups exist on the surface of the low dielectric constant film after the formation of the low dielectric constant film. It is done. Since the Si—H group is a hydrophobic functional group, the hydrophobicity of the film is increased.

  The wavelength of ultraviolet rays used for the ultraviolet irradiation annealing treatment of the low dielectric constant film is generally in the range of 172 nm to 308 nm, and has a lower energy than the band gap of the Si—H group. For this reason, the Si—H group is present stably without dissociating the bonds upon irradiation with ultraviolet rays. Due to this stable Si—H group, the hydrophobicity of the film is maintained at a high level even when an ultraviolet irradiation annealing treatment is performed.

  In general, a film using a silica raw material such as a porous silica film is characterized by high hydrophilicity. This is due to the ability of silanol groups exposed on the surface of the membrane to capture moisture in the air. Since the silanol groups present on the film surface capture water molecules in the air by hydrogen bonds, the ability to adsorb water molecules is high. This phenomenon leads to a decrease in the hydrophobicity of the membrane. This is a property that a film using a silica raw material essentially has. Porous silica membranes have pores and thus have a large surface area, and many silanol groups are exposed on the surface, so that they are more hydrophilic than membranes that do not have pores.

  The above-mentioned property of the porous silica film becomes a problem when it is used as an interlayer insulating film of a multilayer wiring LSI. When the interlayer insulating film absorbs moisture, it causes an increase in dielectric constant and causes an increase in leakage current.

  The low dielectric constant film obtained by the method for producing a low dielectric constant film according to the present embodiment has a large number of Si-H bonds on the film surface, and the content of silanol groups is relatively suppressed. . For this reason, it is considered that the hydrophobicity of the film is kept at a high level and the dielectric constant is kept at a low level.

  In the step of preparing the precursor composition, the dielectric constant can be changed by changing the compounding ratio of the silylating agent and the silica source. For example, as shown in the examples described later, the relative dielectric constant decreases if the amount of the silylating agent is increased with respect to the silica source. Furthermore, the change in relative permittivity is small even when irradiated with ultraviolet rays.

  Note that the relative dielectric constant of the low dielectric constant film can also be changed by changing the molecular weight or addition amount of the thermally decomposable compound. By changing the molecular weight or addition amount of the thermally decomposable compound, the vacancies in the resulting low dielectric constant film change. It is also possible to lower the relative dielectric constant by increasing the porosity in the low dielectric constant film.

As described below, a low dielectric constant film was produced, and the relative dielectric constant of the produced low dielectric constant film was measured.
(Precursor composition mixing)
After putting 6.07 ml of diethoxymethylsilane (Trichemical Laboratories, Electronics Industry Grade) and 2.77 ml of tetraethoxysilane (Trichemical Laboratories, Electronics Industry Grade) in a PFA container, 360 ml of pure water and 34% hydrochloric acid ( 0.9 ml of a mixture with 0.098 ml of electronic industry grade) and 11.08 ml of ethanol (electronic industry grade) were mixed.

  Cap the PFA container, reflux in a water bath heated to 60 ° C. for 90 minutes, cool in running water, add 0.49 ml of a mixture of 9.35 ml of pure water and 0.40 ml of 34% hydrochloric acid, Further, 3.14 ml of pure water was added. After covering with a lid and stirring for 15 minutes at room temperature, the mixture was aged for 15 minutes in a water bath heated to 50 ° C., cooled with running water, and 23.05 ml of ethanol was added.

  After putting 30 ml of ethanol in another PFA container, 2.06 g of surfactant Brij-78 (α-octadecyl ω-hydroxypoly (oxyethylene)) was added and stirred for 1 hour until the solution became transparent. This solution was added to the above diethoxymethylsilane / tetraethoxysilane solution, followed by stirring overnight at room temperature.

(Film formation)
The precursor composition obtained on a 2-inch silicon substrate was spin-coated (2000 rpm, 30 seconds) to form a film.

(Dry)
Then, it was immediately dried for 90 seconds on a hot plate heated to 150 ° C. to remove the solvent.

(Baking)
In an annealing furnace purged with nitrogen, the substrate was baked at a silicon substrate temperature of 350 ° C. for 3 hours (the temperature rising / falling rate was 1 ° C./min) to eliminate the surfactant.

(UV treatment)
Excimer light (Xe lamp, wavelength 172 nm, 15 mW / cm ² ) was irradiated for 300 seconds in an ultraviolet irradiation apparatus purged with nitrogen at a silicon substrate temperature of 350 ° C. And the infrared spectrum and relative dielectric constant were measured for excimer light irradiation for 20 seconds, 60 seconds, 120 seconds, and 300 seconds, respectively.

(Measurement of infrared spectrum)
The chemical bonding state of the hydrophobic low dielectric constant film formed on the high resistivity silicon substrate of 1-10 Ω · cm is performed using a Fourier transform infrared spectrophotometer (JASCO, FT / IR-660 plus), After setting the sample in a nitrogen purged chamber, the infrared transmittance was measured. A bare silicon wafer was used as a reference wafer.

The measured infrared transmission spectrum is shown in FIG. Silanol groups with isolated silanol groups, water molecules, etc., that is, non ^- hydrogen bonded have absorption around 3745 cm ⁻¹ , and hydrogen bonded silanol groups have absorption at 3000-3745 cm ⁻¹ . Also, the moisture in the film is specified by absorption of 3000 to 3745 cm ⁻¹ . In this measurement, only very small absorption was observed in the range of 3000 to 3745 cm ⁻¹ . This indicates that there are almost no isolated silanol groups, hydrogen-bonded silanol groups, or moisture in the film. In addition, no increase in isolated silanol groups, hydrogen-bonded silanol groups, or moisture in the film was observed even after excimer light (ultraviolet light) irradiation.

(Measurement of relative permittivity)
The relative dielectric constant of the prepared film was measured by the following method. An aluminum electrode having a diameter of 2 mm was formed on the formed film by vacuum deposition, and the stage was baked at 200 ° C. for 5 hours in a nitrogen purged chamber to remove adsorbed water. Thereafter, the relative dielectric constant was measured. The results are shown in FIG. As shown in FIG. 2, the relative dielectric constant was 1.79 to 1.82 when irradiated with ultraviolet light for 2 minutes or less in a nitrogen atmosphere, and the relative dielectric constant was 1.92 when irradiated with ultraviolet light for 5 minutes. Thus, it can be seen that the relative permittivity is not greatly reduced by the ultraviolet irradiation. Further, since the difference between the measured value in the nitrogen atmosphere and the measured value in the air is small, it can be seen that the hydrophobicity is also kept high.

  A low dielectric constant film was prepared in the same manner as in Example 1 except that the amounts of diethoxymethylsilane and tetraethoxysilane were 4.04 ml and 5.55 ml, respectively. The obtained low dielectric constant film was measured for infrared transmission spectrum and relative dielectric constant in the same manner as in Example 1.

The measurement results of the infrared transmission spectrum are shown in FIG. As can be seen from FIG. 3, the isolated silanol group 3745Cm ^-1, absorption due to hydrogen bonding of silanol groups and Makuchu moisture 3000-3745Cm ^-1 it is very small. This indicates that there are very few isolated silanol groups, hydrogen-bonded silanol groups, and moisture in the film. Also, no increase in isolated silanol groups, hydrogen-bonded silanol groups, and moisture in the film after UV irradiation was observed.

  The measurement result of the relative permittivity is shown in FIG. As shown in FIG. 4, the relative dielectric constant was 1.92 to 1.94 when irradiated with ultraviolet light for 2 minutes or less in a nitrogen atmosphere, and the relative dielectric constant was 2.1 when irradiated with ultraviolet light for 5 minutes. Thus, it can be seen that the relative permittivity is not greatly reduced by the ultraviolet irradiation. Further, since the difference between the measured value in the nitrogen atmosphere and the measured value in the air is small, it can be seen that the hydrophobicity is also kept high.

  In the same method as in Example 1, the amounts of diethoxymethylsilane and tetraethoxysilane were set to 2.02 ml and 8.31 ml, respectively, to produce a low dielectric constant film. Thereafter, the infrared transmission spectrum and the relative dielectric constant were measured in the same manner as in Example 1.

The measurement result of the infrared transmission spectrum is shown in FIG. As can be seen from FIG. 5, absorption due to 3745 cm ⁻¹ isolated silanol groups, 3000-3745 cm ⁻¹ hydrogen bonded silanol groups and moisture in the film is very small. This indicates that there are very few isolated silanol groups, hydrogen-bonded silanol groups, and moisture in the film. In the transmission spectrum after ultraviolet irradiation, an increase in isolated silanol groups, hydrogen-bonded silanol groups, and moisture in the film was observed.

  The measurement result of the relative dielectric constant is shown in FIG. As shown in FIG. 6, the relative dielectric constant was 2.10 to 2.25 when irradiated with ultraviolet light for 2 minutes or less in a nitrogen atmosphere, and the relative dielectric constant was 2.55 when irradiated with ultraviolet light for 5 minutes.

(Reference Example 1)
As shown below, a low dielectric constant film was produced based on the production method described in Non-Patent Document 1, and an infrared transmission spectrum and a relative dielectric constant were measured in the same manner as in Examples 1 to 3.

(Preparation of precursor composition)
After putting 11.08 ml of tetraethoxysilane (Trichemical Laboratories, Electronics Industry Grade) into a PFA container, 0.9 ml of a mixture of 360 ml of pure water and 0.098 ml of 34% hydrochloric acid (Electronic Industry Grade), ethanol ( Electronic industrial grade) 11.08 ml was mixed.

  Cap the PFA container, reflux in a water bath heated to 60 ° C. for 90 minutes, cool in running water, add 0.49 ml of a mixture of 9.35 ml of pure water and 0.40 ml of 34% hydrochloric acid, Further, 3.14 ml of pure water was added. After covering with a lid and stirring for 15 minutes at room temperature, the mixture was aged for 15 minutes in a water bath heated to 50 ° C., cooled with running water, and 23.05 ml of ethanol was added.

  After putting 30 ml of ethanol into another PFA container, 3.00 g of surfactant Brij-78 was added and stirred for 1 hour until the solution became transparent. After this solution was added to the tetraethoxysilane solution, the solution was stirred overnight at room temperature.

(Film formation)
The obtained precursor composition was deposited on a 2-inch silicon substrate by spin coating at 2000 rpm.

(Dry)
Thereafter, it was immediately dried for 90 seconds on a hot plate heated to 150 ° C.

(Baking)
The silicon substrate temperature was heated to 350 ° C. in an annealing furnace purged with nitrogen, and baked for 30 minutes while flowing tetramethylcyclotetrasiloxane gas (1 g / min) and pure nitrogen (1 L / min) into the baking furnace. . Subsequently, in order to increase the degree of siloxane polymerization of tetramethylcyclotetrasiloxane adsorbed on the nanopore surface, it was calcined at 400 ° C. for 3 hours in an oxygen atmosphere (nitrogen 2.5 L / min, oxygen 0.8 L / min).

(Hydrophobic treatment)
In order to silylate the silanol group generated at this time, firing in a tetramethylcyclotetrasiloxane gas atmosphere was performed again under the same conditions as above.

(UV treatment)
Excimer light (Xe lamp, wavelength 172 nm, 15 mW / cm ² ) was irradiated for 120 to 300 seconds at a silicon substrate temperature of 350 ° C. in an ultraviolet irradiation apparatus purged with nitrogen.

  After the low dielectric constant film was produced by the above method, the infrared transmission spectrum and the relative dielectric constant were measured by the same method as other examples.

As shown in FIG. 7, the isolated silanol group 3745Cm ^-1, absorption due to hydrogen bonding of silanol groups and Makuchu moisture 3000～3745Cm ^-1 it was found to increase significantly by UV irradiation.

  Further, as shown in FIG. 8, the measured value of the relative dielectric constant in the nitrogen atmosphere increases with the ultraviolet irradiation time, and it can be seen that the low dielectric constant performance of the film is deteriorated by the ultraviolet light. Further, the difference between the measured value of the relative dielectric constant in the nitrogen atmosphere and that in the air also increases with the ultraviolet irradiation time. This means that the hydrophobicity of the film is greatly reduced with ultraviolet irradiation.

  Comparing the low dielectric constant films of Examples 1 to 3 with the low dielectric constant film of the reference example, the low dielectric constant films of Examples 1 to 3 are highly hydrophobic and highly resistant to ultraviolet irradiation. found. That is, it was found that the low dielectric constant film according to the present invention has a low content of silanol groups and an increase in silanol groups due to ultraviolet irradiation is suppressed.

  Further, in Examples 1 to 3, low dielectric constant films were produced with different blending ratios of the silylating agent and the silica source, but different relative dielectric constants were obtained depending on the blending ratio of the silylating agent and the silica source. It was found that a low dielectric constant film can be produced. As shown in Example 1, 6.07 ml of diethoxymethylsilane as the silylating agent, 2.77 ml of tetraethoxysilane as the silica source, and the ratio of the low dielectric constant film obtained when the compounding ratio of the silylating agent is increased. It can be seen that the dielectric constant is low and the change in relative dielectric constant is small even when irradiated with ultraviolet rays.

  The low dielectric constant film obtained by using the low dielectric constant film precursor composition according to the present invention has a low dielectric constant, high hydrophobicity, and high ultraviolet radiation resistance. A multilayer wiring LSI using this low dielectric constant film has a reduced leakage current, and a higher level of integration of the multilayer wiring LSI can be expected.

Claims (4)

One or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane and dimethylmethoxysilane;
Formula: (RO) ₃ —Si—X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group, and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group. ), A compound represented by the formula: Si (OR) ₄ (R is a monovalent organic group), one or more substances selected from cyclic siloxane, bicyclic siloxane and zeolite microcrystals,
A thermally decomposable compound;
An alkoxysilane hydrolysis catalyst;
A precursor composition for a low dielectric constant film, comprising: Diethoxymethylsilane,
Tetraethoxysilane,
A thermally decomposable compound;
An alkoxysilane hydrolysis catalyst;
A precursor composition for a low dielectric constant film, comprising: One or more compounds selected from diethoxymethylsilane, dimethoxymethylsilane, diethoxydisilane, dimethoxydisilane, triethoxysilane, trimethoxysilane, dimethylethoxysilane, and dimethylmethoxysilane, and a formula: (RO) ₃ —Si— A compound represented by the formula: X—Si— (RO) ₃ (RO is an alkoxy group, X is an organic crosslinking group and is selected from a methylene group, an ethylene group, a vinylene group, and a 1,4-phenylene group), a formula: One or more substances selected from a compound represented by Si (OR) ₄ (R is a monovalent organic group), cyclic siloxane, bicyclic siloxane, and zeolite microcrystal; a thermally decomposable compound; Preparing a precursor composition comprising a cracking catalyst;
A film forming step of forming the precursor composition on a substrate;
A drying step of drying the film obtained in the film forming step;
A firing step of firing the film obtained in the drying step;
An ultraviolet treatment step of subjecting the film obtained in the firing step to ultraviolet treatment;
A method for producing a low dielectric constant film, comprising: Preparing a precursor composition comprising diethoxymethylsilane, tetraethoxysilane, a thermally decomposable compound, and an alkoxysilane hydrolysis catalyst;
A film forming step of forming the precursor composition on a substrate;
A drying step of drying the film obtained in the film forming step;
A firing step of firing the film obtained in the drying step;
An ultraviolet treatment step of subjecting the film obtained in the firing step to ultraviolet treatment;
A method for producing a low dielectric constant film, comprising:

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