JP5131602B2 - Zeolite raw material liquid, zeolite crystal preparation method, zeolite raw material liquid preparation method, and zeolite thin film - Google Patents

Description

The present invention relates to a zeolite raw material liquid, a zeolite crystal preparation method, a zeolite raw material preparation method, and a zeolite thin film as raw materials used for an interlayer insulating film or the like of a next-generation semiconductor device.

Zeolite is an inorganic crystalline material having small pores, and the pore size is uniform. Compared with amorphous mesoporous silica, zeolite has a high local regular structure, and as a result, is excellent in chemical stability, mechanical strength, and thermal conductivity. Also, zeolite containing aluminum is hydrophilic, but pure silica zeolite is hydrophobic and hardly adsorbs water.

As for this zeolite, it has already been reported that MFI type pure silica zeolite has the potential as an excellent low dielectric constant material (see Patent Documents 1 to 12 and Non-Patent Documents 1 to 5).
US Pat. No. 6,573,131 US Pat. No. 6,630,696 JP-T-2004-504716 JP 2003-249495 A JP 2004-79582 A US Pat. No. 6,533,855 US Pat. No. 6,656,243 US Pat. No. 6,660,245 US Pat. No. 6,329,062 JP 2004-149714 A JP 2004-153147 A International Patent PCT WO 2004 / 026765A1 Z. Wang, H. Wang, A. Mitra, L. Huang, Y. Yan, Pure-silica zeolite low-k dielectric thin films, AdvancedMaterials, 13 (10), 2001,746-749. Z.Wang, A. Mitra, H. Wang, L. Huang, Y. Yan ,. Pure silica zeolitefilms as low-k dielectric by spin-on of nanoparticle suspensions, Advanced Materials, 13 (19), 2001, 1463-1466 . S. Li, Z. Li, Y. Yan, Ultra-low-k pure-silica zeolite MFI films using cyclodextrin as porogen, AdvancedMaterials, 15 (18), 2003, 1528-1531. O. Larlus, S. Mintova, V. Valtchev, B. Jean, TH Metzger, T. Bein, Silicalite-1 / polymer films with low-k dielectric constants, Applied Surface Science, 226 (1-3), 2004, 155 -160. Miki Egami, Characteristics of Semiconductor Device Porous Silica Thin Films, Science and Industry, 77 (11), 2003, 582-587.

In the above-mentioned Patent Documents 1 and 3 and Non-Patent Document 1, Wang Masaho et al. Put TEOS, TPAOH and water as raw materials into a Teflon (registered trademark) autoclave and mixed well, and dipped the silicon substrate. The results of in situ growth of an MFI type zeolite crystal film on the surface in a heating environment are disclosed. The film thus obtained was excellent in mechanical strength (Young's modulus 30 to 40 GPa) and exhibited a low dielectric constant of 2.7 to 3.3. Although there remains a big problem regarding the compatibility of the in-situ crystallization technology of zeolite with the semiconductor manufacturing technology, the high-potential of the zeolite polycrystalline thin film has been proved in principle.

In addition, in the above-mentioned Patent Documents 1, 2, 3 and Non-Patent Document 2, Wang Masataka et al. Have performed film formation by spin coating using a known method for MFI-type zeolite nanocrystal solution synthesis by hydrothermal synthesis. Is disclosed. After solution synthesis, large-diameter crystals were removed by short-time low-speed centrifugation, and the remaining solution was spin-coated on the substrate. The obtained membrane has a two-layered pore structure composed of 0.56 nanometer micropores inherent to MFI-type zeolite and 2 to 17 nanometer interparticle mesopores. The dielectric constant was controlled in the range of 1.8 to 2.1 by the latter control. In addition, by using γ-cyclodextrin as a pore-forming agent, the mesoporosity was increased, and a dielectric constant of 1.6 to 1.7 was successfully realized with an MFI type pure silica zeolite-based film. However, as the mesoporosity is increased, an increase in hygroscopicity and a decrease in mechanical strength are inevitable. Although Wang Masataka et al. Obtained a pure silica low-k film by spin-coating a liquid containing nanocrystals on a silicon substrate, no experimental results have been shown to prove the surface flatness of the film. It was. Rather, it was stated that the surface of the film prepared by spin coating must be polished for 10 minutes with a liquid containing alumina particles, or the film should be subjected to secondary growth to obtain surface flatness. . In fact, when a follow-up experiment was conducted according to the described method, the surface of the obtained film was so rough that it was so severe that meaningful data could not be obtained by thin film measurement by spectroscopic ellipsometry.

In addition, in the above-mentioned Patent Documents 4 and 5, Wang Masataka et al. Have stated that the improvement of flatness and pore size distribution should occur by mixing organic substances and polymers into the liquid, but the demonstration data is not shown at all. It wasn't. Although the inner pore surface of pure silica zeolite is hydrophobic, the outer surface of the zeolite crystal grains and the amorphous silica surrounding it have silanol (—OH) groups and consequently show hydrophilicity. Therefore, Wang Masataka et al. Mixed 50 weight percent of methyl into the spin coating solution with MTMS or the like in order to make the entire film hydrophobic, thereby succeeding in hydrophobicity.

In the method of Gaynor, as shown in the above-mentioned Patent Documents 6, 7, 8, and 9, a porous low dielectric constant material composed of two components of an MFI zeolite crystal and a porous binder was invented. Its dielectric constant was 2.15 to 2.45, and Young's modulus was 5 GPa or less. A porous binder was synthesized by adding a small amount of acidic water to an ethyl alcohol solution of TEOS hydrolyzed with amorphous silica containing pores of 5% or less. However, they do not provide data on the surface flatness and pore size distribution of the films thus obtained.

In the method of Lalarus et al., As shown in Non-Patent Document 4 above, a dielectric constant of 2.0 to 2.56 was realized using a porous irregular structure composite of MFI zeolite and an acrylic rubber polymer. Although the surface flatness of the obtained thin film is claimed, its mechanical strength and pore size distribution are not described.

Miki Egami et al. Reported a low dielectric constant film having a dielectric constant of 2.3 and a Young's modulus of 8 to 10 GPa, as shown in Patent Documents 10 and 11 and Non-Patent Document 5 described above. The production method is spin coating of a liquid containing MFI type zeolite crystals. After heat treatment at 400 degrees Celsius after spin coating, it is reported that the peak due to the MFI type zeolite structure that should appear in the Fourier transform infrared spectrum disappears. Miki Egami et al. Also disclosed a method for producing a low dielectric constant thin film (dielectric constant of 2.5 or less, Young's modulus of 6 GPa or more) of hydrophobic amorphous silica. TEOS was used as a silica raw material, TPAOH or TBAOH was used as a template molecule, MTMS or MTES was used as a methyl source for promoting the hydrophobicity of the film, and ethyl alcohol was used as a solvent. The reaction temperature is as low as 50 degrees Celsius and the reaction time is as short as 20 hours. Even after further trials under these reaction conditions, no zeolite crystals were detected in the liquid. Although these membranes are similar to zeolite in the synthesis method, it can be said that the resulting membrane is a porous silica membrane.

Takamura et al. Described that the mechanical strength of the MFI-type zeolite low dielectric constant film is improved by treating with TMCTS as shown in Patent Document 12 above. However, the method for producing MFI-type zeolite described therein was the same as the method of Wang Masataka et al., And the reported dielectric constant was a fairly high value of 3.2.

As described above, in each of the prior documents, a pure silica film having a low dielectric constant has been obtained by spin-coating a solution containing particles of various sizes. However, all the thin films are composed of MFI type zeolite crystals. Moreover, the data which show the surface flatness of a thin film are not shown, but sufficient surface flatness is not acquired. Also, the hydrophobicity was not sufficient. Furthermore, since the synthesis methods in each of the above-mentioned prior art documents inevitably generate large grains, centrifugation is required prior to spin-coating a solution containing MFI-type zeolite crystals, and the preparation process becomes complicated. The cost is also higher.

This invention has been proposed in view of the above, and even when a zeolite crystal other than MFI type is a main component, sufficient strength of the zeolite thin film can be secured, dielectric constant reduction, surface flatness improvement, An object of the present invention is to provide a zeolite raw material liquid, a zeolite crystal preparation method, a zeolite raw material liquid preparation method, and a zeolite thin film, which can improve the hydrophobicity and further reduce the cost by simplifying the preparation process. To do.

In order to achieve the above object, the invention described in claim 1 is a raw material liquid for zeolite, and is characterized by comprising MEL-type zeolite nanocrystals as a main component.

The invention according to claim 2 is a method for preparing zeolite nanocrystals, wherein a synthesis solution comprising TEOS, TBAOH, water, and alcohol is aged, and then subjected to hydrothermal synthesis treatment at a predetermined temperature to form a MEL type. It is characterized by producing zeolite nanocrystals.

The invention according to claim 3 is a method for preparing a raw material liquid for zeolite, wherein a synthesis solution comprising TEOS, TBAOH, water and alcohol is aged, and then hydrothermal synthesis treatment is performed at a predetermined temperature. An MEL-type zeolite nanocrystal is prepared, and the zeolite crystal solution containing the MEL-type zeolite nanocrystal is mixed with at least one organic solvent such as an alcohol-based organic solvent, an amide-based organic solvent, or a ketone-based organic solvent, or a mixture of two or more. It is characterized by preparing a raw material liquid for zeolite by mixing an organic solvent.

The invention according to claim 4 is a method for producing a raw material liquid for zeolite, wherein a synthesis solution comprising TEOS, TBAOH, water and alcohol is aged, and then hydrothermal synthesis treatment is performed at a predetermined temperature. MEL-type zeolite nanocrystals are prepared, and a surfactant is added to the zeolite crystal solution containing the MEL-type zeolite nanocrystals, and at least one organic solvent such as an alcohol-based organic solvent, an amide-based organic solvent, or a ketone-based organic solvent, or A raw material liquid for zeolite is prepared by mixing a composition obtained by dissolving in two or more mixed organic solvents.

The invention according to claim 5 is a method for producing a raw material liquid for zeolite, which is a MEL type by hydrolyzing a synthesis solution composed of TEOS, TBAOH, water and alcohol and then hydrothermally synthesizing at a predetermined temperature. The zeolite nanocrystal is prepared, and the surfactant is added to the zeolite crystal solution containing the MEL-type zeolite nanocrystal. The surfactant is at least one organic solvent such as an alcohol organic solvent, an amide organic solvent, or a ketone organic solvent, or two or more. The composition obtained by dissolving in a mixed organic solvent is mixed, and a methyl group is added to the mixed solution to prepare a raw material liquid for zeolite.

In the invention described in claim 6, in addition to the constitution of the invention described in claim 4 or 5, the ratio of the surfactant to the organic solvent is 0.1 to 1.5% by weight. It is a feature.

The invention described in claim 7 is characterized in that, in addition to the constitution of the invention described in claim 4 or 5, the concentration of the composition with respect to the zeolite crystal solution is 5 to 50%.

The invention described in claim 8 is characterized in that, in addition to the constitution of the invention described in claim 5, the volume fraction of the methyl group with respect to the zeolite crystal solution is 1 to 10%.

In the invention described in claim 9, in addition to the constitution of the invention described in claim 4 or 5, the surfactant comprises (a) an amphiphilic triblock copolymer (polyethylene oxide-polypropylene oxide-polyethylene oxide). ), L series such as L31, L35, L43, L44, L61, L62, L62D, L62LF, L64, L81, L92, L10, L101, L121, P65, P84, P85, P103, P104, P105, P123 P series like F38, F68, F68LF, F77, F87, F88, F98, F108, F127 like R series, R series like 10R5, 17R2, 17R4, 25R2, 25R4, 31R1, (b ) diblock copolymer _{(C n H 2n + 1 (} OCH 2 CH 2) x OH, n = 12-18, and x = 2-100) in this, a mixture of one or (a) and of (b), the characterized in that.

In the invention described in claim 10, in addition to the constitution of the invention described in any one of claims 4 to 8, the surfactant includes (c) an alkyltrimethylammonium bromide such as C ₁₆ H ₃₃ N ( CH ₃ ) ₃ Br (HTMABr), alkyltriethylammonium bromide, eg C ₁₆ H ₃₃ N (C ₂ H ₅ ) ₃ Br (HTEABr), (d) alkyltrimethylammonium chloride, eg C ₁₂ H ₂₅ N (CH ₃ ) ₃ Cl (C ₁₂ TAC), C ₁₄ H ₂₉ N (CH ₃ ) ₃ Cl (C ₁₄ TAC), C ₁₈ H ₃₇ N (CH ₃ ) ₃ Cl (C ₁₈ TAC), or (c) It is a mixture of (d).

In addition to the constitution of the invention according to any one of claims 3 to 10, the alcohol-based organic solvent includes 1-propanol, 2-propanol, 1-butanol, 2- Butanol is included, the amide organic solvent includes N, N′-dimethylformamide, N, N′-dimethylacetamide, N-methylpyrrolidinan, and the ketone organic solvent includes acetone and methyl ethyl ketone. It is characterized by that.

In the invention described in claim 12, in addition to the structure of the invention described in claim 5, the methyl group is at least one of methyltriethoxysilane, dimethyldiethoxysilane, and trimethylethoxysilane. It is characterized by.

The invention described in claim 13 is a zeolite thin film, which is prepared by spin-coating a raw material liquid for zeolite prepared by the method according to any one of claims 3 to 12 on a substrate. It is characterized by.

In this invention, after aging a synthesis solution composed of TEOS, TBAOH, water, and alcohol, hydrothermal synthesis treatment is performed at a predetermined temperature to produce MEL-type zeolite nanocrystals. Since the zeolite raw material liquid is prepared by mixing the organic solvent with the zeolite crystal solution it contains, it is possible to ensure sufficient strength of the zeolite thin film even when the main component is MEL-type zeolite nanocrystals. A high Young's modulus of about 10 to 12 GPa could be obtained.

Also, the relative dielectric constant could be reduced to 2.0, and high surface flatness could be obtained.

Further, the refractive index of the film is as low as about 1.12, and it can be used as an extremely low refractive index film excellent in mechanical strength.

Moreover, since a raw material liquid for zeolite was prepared by mixing a surfactant, it was possible to further reduce the refractive index and the dielectric constant, and to narrow the mesopore size distribution.

Moreover, since the methyl group was added to the raw material liquid for zeolite, the hydrophobicity could be greatly improved.

Furthermore, since the zeolite raw material liquid is mainly composed of more uniform MEL-type zeolite nanocrystal grains, it is not necessary to centrifuge the obtained raw material liquid for zeolite, and a thin film is formed on the substrate as it is. Can be transferred to the step of forming the film. Therefore, it is possible to reduce the cost by simplifying the production process.

It is a figure which shows roughly the procedure of the zeolite thin film preparation concerning this invention. It is a figure which shows the Fourier-transform infrared absorption spectrum of the zeolite thin film in Example 1. FIG. It is a figure which shows the relationship between the TMCTS processing time in the zeolite thin film of Example 1, and the contact angle of water. It is a figure which shows the change of the refractive index of a zeolite thin film by a TMCTS process in Example 1, and a dielectric constant. In Example 2, it is a figure which shows the influence which surfactant has on the hole diameter distribution of a zeolite thin film. It is a figure which shows the infrared absorption spectrum change by the methyl group addition in the zeolite thin film of Example 4, and the hydrophobic improvement effect. It is a figure which shows the measurement result of Examples 1-4 and a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram schematically showing a procedure for producing a zeolite thin film according to the present invention. A raw material liquid for zeolite for producing a zeolite thin film (nanoporous low dielectric constant thin film) is composed of the following three compositions. (A) a zeolite crystal solution containing hydrothermally synthesized MEL-type pure silica zeolite crystals (zeolite nanocrystals), (b) a surfactant for controlling surface flatness and mesopore structure, and (c) Additive to enhance hydrophobicity.

First, in step S1 and step S2 of FIG. 1, a composition (a) is prepared. The synthesis method of the zeolite crystal solution containing the MEL-type zeolite nanocrystal of the composition (a) is as follows. The molar composition ratio of the synthetic raw material liquid is 1.0 TEOS: 3.6 TBAOH: 12H ₂ O: X alcohol. Here, TEOS is tetraethylorthosilicate, and TBAOH is tetrabutylammonium hydroxide.

As the alcohol, methanol, ethanol, propanol, butanol, or a mixture of two or more of them is used. The value of the molar concentration ratio “X” is 0 to 5,
More preferably 0.5 to 1, and most preferably 0.85 is employed. The reaction temperature range is 90-120 ° C, preferably 95-115 ° C, and most preferably 100 ° C.

The clear liquid of the above mixing ratio is stored at room temperature (23 ° C.) in a capped PFA (Teflon (registered trademark)) container for 10 to 30 hours, most preferably 20 hours with good stirring. Thereafter, the container containing the liquid is placed in a heater oven and subjected to hydrothermal synthesis while stirring. By setting the reaction temperature at 90 to 120 ° C., preferably 95 to 115 ° C., and most preferably 100 ° C., nano-sized MEL-type zeolite crystal grains (zeolite nanocrystals) can be obtained.

The synthesis time depends on the reaction conditions. In a one-step reaction process, i.e. a process in which crystallization is completed in one reaction process, the reaction time was 40-150 hours, most preferably 120 hours. In the two-stage reaction process, the first stage process time is 48 to 72 hours, and the second stage process time is 10 to 20 hours. Most preferably, the first stage is 60 hours and the second stage is 12 hours.

While it is necessary to remove large crystal grains by centrifugation after synthesizing MFI type pure silica zeolite crystals, after the MEL type pure zeolite crystal synthesis of the present invention, the size of the crystal grains is almost the same. Is unnecessary.

Next, said composition (b) is prepared. The composition (b) is used by dissolving 0.1 to 1.5 weight percent of a surfactant in an organic solvent. Here, the organic solvent means (1) an alcohol-based organic solvent (for example, 1-propanol, 2-propanol, 1-butanol, 2-butanol), (2) an amide-based organic solvent (for example, N, N′-dimethylformamide) (DMF), N, N′-dimethylacetamide (DMA), N-methylpyrrolidinan (NMP)), (3) any one of ketone organic solvents (for example, acetone, methyl ethyl ketone) or a mixture thereof To do.

The surfactant is (a) an amphiphilic triblock copolymer (polyethylene oxide-polypropylene oxide-polyethylene oxide), such as L31, L35, L43, L44, L61, L62, L62D, L62LF, L64, L81, L92, L series such as L10, L101, L121, P series such as P65, P84, P85, P103, P104, P105, P123, F38, F68, F68LF, F77, F87, F88, F98, F108, F127 F series such as, R series such as 10R5, 17R2, 17R4, 25R2, 25R4 and 31R1, (b) diblock copolymer (C _n H _{2n + 1} (OCH ₂ CH ₂ ) _x OH, where n = 12 -18, and x = 2-100), or a mixture of (a) and (b). Also, (c) alkyltrimethylammonium bromide such as C ₁₆ H ₃₃ N (CH ₃ ) ₃ Br (HTMABr), alkyltriethylammonium bromide such as C ₁₆ H ₃₃ N (C ₂ H ₅ ) ₃ Br (HTEABr), ( d) alkyl trimethyl ammonium chloride, for example, _{C 12 H 25 N (CH 3} ) 3 Cl (C 12 TAC), C 14 H 29 N (CH 3) 3 Cl (C 14 TAC), C 18 H 37 N (CH 3 ) ₃ Cl (C ₁₈ TAC) or a mixture of (c) and (d).

Next, a composition (c) is prepared. The composition (c) is a methyl group such as methyltriethoxysilane, dimethyldiethoxysilane, or trimethylethoxysilane.

Returning to FIG. 1, in step S3, the above composition (b) is completely mixed with the zeolite crystal solution (composition (a)) containing the zeolite nanocrystals obtained in the above step S1, and the composition The material (c) is mixed to prepare a zeolite raw material liquid (step S4).

The density | concentration with respect to the composition (a) of a composition (b) is controlled in 5 to 50% of range. Preferably it is 20%.

The volume fraction of the composition (c) is 1 to 10%, preferably 5% with respect to the composition (a).

Here, the composition (b) is considered to contribute to the improvement of the surface flatness, the reduction of the refractive index, the reduction of the dielectric constant, and the uniform size of the mesopores. The composition (c) is for improving hydrophobicity.

Next, in step S5, spin coating is performed on the substrate. That is, the zeolite raw material liquid obtained by mixing the compositions (a), (b), and (c) is spin-coated on a 200 mm diameter silicon wafer. The rotation speed of the substrate during spin coating is 500 to 4000 revolutions per minute, desirably 1500 to 2500 revolutions, and most desirably 2000 revolutions. The time for spin coating is 5 to 80 seconds, desirably 10 to 40 seconds, and most desirably 20 seconds. The resulting film is very flat and has no striations.

The thin film obtained by spin coating is then subjected to heat treatment at 90 ° C. for 2 hours, followed by removal of organic components in the film by baking in air at 400 ° C. for 2 to 8 hours (optimal value is 5 hours). The heating rate is 1 ° C. per minute.

The zeolite thin film prepared by the above procedure was evaluated as follows. For measurement of refractive index and film thickness, a spectroscopic ellipsometer of GES-5 type manufactured by Sopra, France was used. A Hitachi S4700 scanning electron microscope was used for surface observation of the obtained film. The presence of the MEL-type zeolite structure was confirmed by X-ray diffraction measurement and measurement by an Excalibur type Fourier transform infrared spectrometer manufactured by Digilab. The Young's modulus was measured using an XP type nanoindenter manufactured by MST, USA. Adsorption spectroscopic ellipsometry was used to measure the pore size distribution. The dielectric constant was measured by using a 4284 precision LCR meter manufactured by Agilent Technologies.

In the above description, in order to improve hydrophobicity, methyl groups were added to prepare a raw material liquid for zeolite. However, without adding methyl groups, the zeolite thin film obtained by spin coating was added to TMCTS ( You may make it perform the annealing process (TMCTS process) in a tetramethyl tetrasiloxane) gas. The optimum temperature for TMCTS treatment on the zeolite thin film obtained in the present invention was 400 ° C., and the optimum treatment time was 25 to 35 minutes.

Moreover, you may make it implement both methyl group addition and TMCTS process for hydrophobicity improvement.

In the above description, the zeolite crystal solution is prepared by mixing both the surfactant (composition) and the methyl group into the zeolite raw material liquid. A raw material liquid for zeolite may be prepared by mixing only an organic solvent. Or you may make it mix only surfactant (composition), without mixing a methyl group. In either case, a zeolite thin film containing MEL-type zeolite nanocrystals as a main component can be prepared, and sufficient strength, low dielectric constant, low refractive index, and high surface flatness can be obtained.

Next, specific examples will be described.

Example 1 15 ml of TEOS was added dropwise to a 40% aqueous solution of TBAOH while stirring. After the entire amount of TEOS had been added dropwise, 15 ml of ethanol was added. The obtained mixed solution was put into a washed PFA container covered with a lid, and stored at room temperature of 23 ° C. for 20 hours. Then, the PFA container and the solution were placed in an electric oven and hydrothermal synthesis was performed for 12 hours while stirring at 100 ° C. The obtained transparent colloidal solution was gradually cooled to 23 ° C. with stirring to obtain a colloidal solution (zeolite crystal solution) of MEL type pure silica zeolite (zeolite nanocrystals). The colloidal solution synthesized under these synthesis conditions did not contain particles that were large enough to be removed by centrifugation. This is different from the result of the synthesis of MFI type pure zeolite solution.

2 ml of 2-butanol was thoroughly mixed with 8 ml of the obtained zeolite colloid solution, and spin coating was applied to a low resistance and high resistance 200 mm diameter silicon wafer using 3 ml of the mixed solution. The rotation speed of the wafer during spin coating was 2000 revolutions per minute, and the spin coating time was 10 minutes. The obtained wafer with MEL type pure silica zeolite thin film was heated in air at 100 ° C. for 2 hours and then heat-treated in air at 400 ° C. The heating rate at that time was 1 ° C. per minute.

In order to examine the surface flatness of the obtained film, shape observation with an optical microscope with a digital camera, film thickness / refractive index measurement with spectroscopic ellipsometry, and scanning electron microscope observation were performed. As a result, no striation was observed. Moreover, the uniformity of the film thickness and the refractive index was confirmed on the entire surface. The refractive index showed a low value of 1.12.

2 is a diagram showing a Fourier transform infrared absorption spectrum of the zeolite thin film in Example 1. FIG. Absorption peak assignments are as follows. 1224 and 1106 cm ⁻¹ (asymmetric Si—O—Si stretching vibration), 810 cm ⁻¹ (symmetric Si—O—Si stretching vibration), 550 cm ⁻¹ (double five-membered ring structure in the zeolite framework), and 453 cm ^−1. (Si-O bending vibration on the inner silica surface). The absorption band near 1224 cm ⁻¹ is found only in zeolites having a 5-membered ring structure. 550 cm ⁻¹ is attributed to asymmetric stretching vibrations in the five-membered ring structure, and lattice-sensitive doublet splitting is the definitive evidence for the existence of the MEL-type zeolite framework. Thus, a peak indicating the presence of MEL-type zeolite is observed, indicating that the zeolite thin film is MEL-type.

The Young's modulus of the obtained film was determined to be 6.5 GPa as a result of nanoindentation measurement. The value of the relative dielectric constant at 100 kHz determined by the capacitance measurement was 2.05.

In order to improve the hydrophobicity and improve the mechanical strength, the membrane was subjected to TMCTS treatment for 15 minutes, 25 minutes, 35 minutes, and 45 minutes, and the results were compared with FIG.

3 is a graph showing the relationship between the TMCTS treatment time and the water contact angle in the zeolite thin film of Example 1. FIG. The horizontal axis in FIG. 3 represents the time for TMCTS treatment, and the vertical axis represents the contact angle of water. As shown in FIG. 3, the contact angle of water is increased from 13 degrees before the treatment to 139 degrees after the treatment by the TMCTS treatment, and it can be seen that the hydrophobicity is improved. In addition, each photograph of the upper stage of FIG. 3 and the lower left shows the state of water when a water drop is dripped on a thin film, and a circular thing is a water drop in each upper photograph.

4 is a graph showing changes in the refractive index and dielectric constant of the zeolite thin film by the TMCTS treatment in Example 1. FIG. The horizontal axis represents TMCTS processing time, the left vertical axis represents the refractive index, and the right vertical axis represents the non-dielectric constant. From this experimental result, it was found that the optimum condition for TMCTS treatment was 15 minutes to 35 minutes at 400 ° C. In addition, the Young's modulus after TMCTS treatment at 400 ° C. for 35 minutes increased to 9.6 GPa.

(Example 2) The triblock copolymer P123 was dissolved in 1 gram of 99 ml of 1-butanol to obtain a composition (b). 8 ml of the composition (a) synthesized under the same conditions as in Example 1 and 2 ml of the composition (b) in Example 2 were thoroughly mixed. 3 ml of the liquid thus obtained was spin-coated on a low resistance and high resistance silicon wafer having a diameter of 200 mm. The rotation speed of the wafer during spin coating and the spin coating time were 2000 revolutions per minute and 10 seconds, respectively. The obtained film was heat-treated in the atmosphere at 90 ° C. for 2 hours, and then fired at 400 ° C. for 5 hours. The heating rate at that time is 1 ° C. per minute. As a result of analysis and evaluation of the obtained film, the refractive index was 1.07 and the dielectric constant was 1.81. These results showed improvement as compared with the results of Example 1 (refractive index: 1.12, dielectric constant: 2.05) in which the composition (b) was not added.

FIG. 5 is a graph showing the influence of the surfactant on the pore size distribution of the zeolite thin film in Example 2. The horizontal axis represents the mesopore diameter (nm), the vertical axis represents the heptane adsorption amount, A represents the case where the surfactant (composition (b)) was added, and B represents the case where it was not added. As shown in FIG. 5, the size distribution of mesopores was narrowed by the addition of the composition (b).

(Example 3) A triblock copolymer L44 was dissolved in 1 gram of 1-butanol (99 ml) to obtain a composition (b). 8 ml of the composition (a) synthesized by the same method as in Example 1 and 2 ml of the composition (b) in Example 3 were thoroughly mixed. 3 ml of the liquid thus obtained was spin-coated on a low resistance and high resistance silicon wafer having a diameter of 200 mm. The rotation speed of the wafer during spin coating and the spin coating time were 2000 revolutions per minute and 10 seconds, respectively. The obtained film was heat-treated in the atmosphere at 90 ° C. for 2 hours, and then fired at 400 ° C. for 5 hours. The heating rate at that time is 1 ° C. per minute. As a result of analysis and evaluation of the obtained film, the refractive index was 1.10 and the dielectric constant was 1.92. These results showed improvement as compared with the results of Example 1 (refractive index: 1.12, dielectric constant: 2.05) in which the composition (b) was not added.

As a result of the mesopore size distribution measurement, no mesopores having a diameter exceeding 2 nanometers were detected. On the other hand, in Example 2, uniform mesopores of about 2 nanometers were obtained. . The molecular weight of P123 used for the composition (b) in Example 2 and L44 used in Example 3 are about twice different. This result suggests controllability of mesopore size by introduction of surfactants with different molecular weights.

Example 4 20 ml of dimethyldiethoxysilane was dissolved in 10 ml of ethanol and stored at 50 ° C. for 20 hours to obtain a composition (C). 8 ml of the composition (a) synthesized by the same method as in Example 1, 2 ml of the composition (b) prepared by the same method as in Example 3, and 1 ml of the composition (c) in this example were completely Mixed. 3 ml of the liquid thus obtained was spin-coated on a low resistance and high resistance silicon wafer having a diameter of 200 mm. The rotation speed of the wafer during spin coating and the spin coating time were 2000 revolutions per minute and 10 seconds, respectively. The obtained film was heat-treated in air at 100 ° C. for 2 hours, and then fired at 400 ° C. for 5 hours. The heating rate at that time is 1 ° C. per minute. As a result of analysis and evaluation of the obtained film, the refractive index was 1.14 and the dielectric constant was 2.06.

FIG. 6 is a diagram showing an infrared absorption spectrum change and a hydrophobicity improving effect by addition of a methyl group in the zeolite thin film of Example 4. The horizontal axis represents the wave number, the vertical axis represents the spectrum, A represents the case where an ethyl group was added, and B represents the case where no ethyl group was added. As shown in FIG. 6, as a result of adding the ethyl group (composition (c)), the Si—OH bond was greatly lowered, and as can be seen from the photograph on the right side, water was used in A (circular in the photograph on the lower right). The contact angle of the film is increased, indicating an improvement in the hydrophobicity of the film.

(Comparative Example) 10 ml of TEOS is dropped into 12.5 ml of 25% aqueous solution of TPAOH with good stirring. After all the TEOS was added, 10 milliliters of ethanol was added. The resulting liquid is stored for 72 hours at room temperature 23 ° C. Then put in a PFA container with a lid and store at 85 ° C. for 66 hours with stirring. The obtained milk-colored colloidal solution of MFI type pure silica zeolite is gradually cooled to room temperature.

Ten milliliters of the resulting liquid was centrifuged at 5000 rpm for 15 minutes, and the supernatant was thoroughly mixed with 2.5 milliliters of dimethylformaldehyde. Three milliliters are spin-coated on a low-resistance / high-resistance silicon wafer having a diameter of 200 mm. The rotation speed of the wafer during spin coating is 2000 revolutions per minute and the spin coating time is 10 seconds. The obtained film was heat-treated in the atmosphere at 90 ° C. for 2 hours, and then fired at 400 ° C. for 5 hours. The heating rate at that time is 1 ° C. per minute. The Young's modulus of the obtained film is 8 to 10 GPa as a result of nanoindentation measurement. The dielectric constant determined by capacitance measurement is 2.2 to 2.7. The mesopore size distribution was 2-11 nm.

The measurement results of Examples 1 to 4 and the comparative example are shown in FIG. As a result of the thin film evaluation in Examples 1 to 4, it was found from FIG. 2 that the thin film had a MEL type zeolite structure.

In the present invention, a synthesis solution comprising TEOS, TBAOH, water, and alcohol is aged, and then hydrothermal synthesis treatment is performed at a predetermined temperature to produce a MEL-type zeolite nanocrystal. The MEL-type zeolite nanocrystal As a raw material liquid for zeolite is prepared by mixing an organic solvent with a zeolite crystal solution containing, a sufficient strength of the zeolite thin film is ensured even when MEL type zeolite nanocrystals are the main component. It was possible to obtain a high Young's modulus of about 10 GPa.

Also, the relative dielectric constant could be reduced to 1.8 to 2.0, and high surface flatness could be obtained.

Further, the refractive index of the film is as low as about 1.1, and it can be used for an optical component as an extremely low refractive index film excellent in mechanical strength.

In addition, since a raw material liquid for zeolite was prepared by mixing a surfactant, the refractive index and dielectric constant can be further reduced, and the mesopore size distribution should be narrowed to improve surface flatness. I was able to.

Moreover, since the methyl group was added to the raw material liquid for zeolite, the hydrophobicity could be greatly improved.

Furthermore, since the zeolite raw material liquid is mainly composed of more uniform MEL-type zeolite nanocrystal grains, it is not necessary to centrifuge the obtained raw material liquid for zeolite, and a thin film is formed on the substrate as it is. Can be transferred to the step of forming the film. Therefore, it is possible to reduce the cost by simplifying the production process.

Claims (4)

A MEL-type zeolite thin film having a SiO bond as a structural main component, wherein the zeolite thin film has a wave number of 550 cm due to a double five-membered ring structure in the zeolite skeleton. ^-1 And having a surface flatness, a refractive index in the range of 1.07 to 1.14 in the visible light region, and a relative dielectric constant of 2.05 or less at a frequency of 100 kHz. A featured zeolite thin film. 2. The zeolite thin film according to claim 1, wherein the relative dielectric constant of the thin film is an arbitrary value within a range of 1.8 to 2.0 . The zeolite thin film according to claim 1, wherein the Young's modulus of the thin film is set to an arbitrary value within a range of 10 to 12 GPa . The raw material liquid for zeolite for preparing the zeolite thin film is (a) a zeolite crystal solution containing MEL-type pure silica zeolite crystal grains (zeolite nanocrystals) synthesized hydrothermally, (b) surface flatness and mesopore structure. Consists of three compositions: a surfactant for controlling and (c) an additive for enhancing hydrophobicity, the concentration of composition (b) to composition (a) being in the range of 5-50% The volume fraction of the composition (c) is an arbitrary value within a range of 1 to 10% with respect to the composition (a). A zeolite raw material liquid for the zeolite thin film according to claim 1 .