JP2979236B2 - Ultra thin polymer film and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultra-thin polymer film and a method for producing the same, and more particularly, to an electric element (MIM, MIS, SIS), patterning (liquid crystal substrate (rubbing treatment)). The present invention relates to an ultra-thin film used in the field of an optical element (optical waveguide, binder resin for a non-linear tertiary element) and the like, and a method for producing the same.

<Prior art> Conventionally, polymer ultrathin films used for electric elements, patterning, optical elements, etc. are smooth, uniform thin films having uniform molecules, and are one of the methods for producing such organic ultrathin films. There is the Langmuir-Projet method (hereinafter abbreviated as LB method). LB
In the method, organic molecules are made into a dilute solution of organic solvent, developed on a clean water surface, and the gas film remaining after the solvent evaporates is compressed in the plane direction to form a solid film with densely packed molecules. This is a method of transferring the solid film to the surface of the solid substrate and then accumulating the solid film. The resulting thin film on the substrate is referred to as an LB film (for example, see KBBlodget
t, J. Am. Chem. Soc., 55, 1007 (1935)), [K.
da et al., J. Colloid Interface Sci. 54,430 (1976)]. LB
The feature of the film is that it can be formed from an ultrathin film of molecular order to a cumulative film of any thickness by repeating lamination, and is a smooth and uniform film with uniform molecular orientation. Therefore
LB films are expected as various materials for electronics, and the conversion of linear fatty acids having 16 or more carbon atoms or their alkaline earth metal salts and cadmium salts into LB films has been widely studied [eg, Kiyonari Fukuda, Hiroo Nakahara (Co-author), Chemistry Review 40 <Molecular Assemblies> pp. 82-104, 1983, and references thereof].
However, the LB films of these fatty acids or metal salts have poor mechanical strength, heat resistance and the like, and have a drawback that they are not practical. Therefore, a method has been devised in which a polymerizable fatty acid is formed into an LB film and then subjected to a polymerization treatment, or a method in which the polymerized fatty acid is polymerized on the water surface and then formed into an LB film (literature, ibid.). Severe cracks and cracks are formed, and transfer to a substrate is extremely difficult.

On the other hand, a method of preparing an LB film using a polymer and accumulating the LB film on a substrate can be considered, but a general polymer has a thread-like aggregated state even in a dilute solution. It does not become a gas film when deployed on the water surface,
It is difficult to form an LB film, and exceptionally, it has been reported that the use of polypeptides and polyitaconates causes the polymer chains to take on a rod-like structure to form an LB film [Reference JHMcAlea
r and others, Symposium on VLSI Technology, Digest of Tech.P
aper, 82 (1981), K. Shigehara et al., J. Amer. Chem. Soc., 12,
37, Vol. 109, (1987)].

Furthermore, in order to provide an insulating layer on various elements, attempts have been made to spin-coat a synthetic polymer solution on a substrate, but the performance required for the insulating layer is that the heat-resistant temperature is at least 200 ° C or higher. It must be thermally and chemically stable and have excellent moisture resistance and mechanical and electrical properties.Polymers that satisfy these requirements are limited, for example, polyimide, polyether Sulfone, polyphenylene sulfide, polysulfone, polyphenylene oxide, polyethylene terephthalate and the like are known. These polymers are dissolved in an organic solvent to prepare a dilute solution, which is spin-coated on a substrate, and then the solvent is evaporated to form an insulating film.For example, as a solvent for dissolving polyimide or polysulfone, A polar solvent such as dimethylacetamide or N-methylpyrrolidone can be used. However, since the solvent is a high-boiling solvent, there is a drawback that the evaporation rate is low and the possibility of remaining in the insulating film is high. In addition, the viscosity of the polymer solution is relatively high, and at present, considerable technology is required to form a uniform and smooth film.

<Problem to be Solved by the Invention> An object of the present invention is to provide a polymer ultrathin film that is mechanically and chemically stable and has heat resistance, and a method for producing the same.

<Means for Solving the Problems> According to the present invention, an itaconic acid diester polymer is formed by a spin coating method or a Langmuir blow jet (LB) method to form an ultrathin polymer film having a thickness of 10 to 1000 mm. The itaconic acid diester polymer is represented by the following general formula (I) (Wherein, R ₁ and R ₂ represent identical or different radicals, R ₁
And at least one of R ₂ is a branched alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituted alkyl having 2 to 6 carbon atoms having a substituent having a ring structure having 3 to 14 carbon atoms. Represents a substituted cycloalkyl group having 3 to 10 carbon atoms or a siloxane-based hydrocarbon group having a substituent of the above-mentioned ring structure, and each of the groups may contain a hetero atom, and may be substituted with a halogen atom. Which may contain a repeating unit of an itaconic acid diester represented by the formula (I): Is done.

Further, according to the present invention, a solution containing 0.1 to 20 mg / m of the itaconic acid diester polymer is produced by spin coating at a rotation speed of 1,000 to 15,000 to produce a polymer ultrathin film. A method is provided.

Furthermore, according to the present invention, a solution containing 0.1 to 3 mg / m of the itaconic acid diester polymer is developed on a water surface,
Applying a pressure to maintain the surface pressure at 3 to 40 mN / m to form a solid film, and obtaining the solid film by a vertical immersion method or a horizontal deposition method by an LB method of accumulating the polymer film. Is provided.

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

In the present invention, the following general formula (I) The itaconic acid diester polymer containing the repeating unit of itaconic acid diester shown by these is used. In the formula, R ₁ and R ₂ represent the same or different groups, and at least one of R ₁ and R ₂ is a branched alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, It represents a substituted alkyl group having 2 to 6 carbon atoms having a substituent having a ring structure of 14, a substituted cycloalkyl group having 3 to 10 carbon atoms having a substituent having a ring structure, or a cycloxane-based hydrocarbon. The branched alkyl group, the cycloalkyl group, the substituted alkyl group, the substituted cycloalkyl group, and the siloxane-based hydrocarbon group may contain a hetero atom such as a nitrogen atom, an oxygen atom, a phosphorus atom, and a sulfur atom. Or a halogen atom.

Examples of the polymer of the diester itaconate having a repeating unit represented by the above general formula (I) include diisopropyl itaconate, di-tert-butyl itaconate, dicyclohexyl itaconate, di-sec-butyl itaconate, and di-itaconate. 4-methyl-2-pentyl, isopropyl-tert-butyl itaconate, isopropyl itaconate-isoamyl, isopropyl-4-methyl-2-pentyl itaconate, isopropyl-2-ethylhexyl itaconate, isopropyl-nonyl itaconate, itaconic acid tert
-Butyl-sec-butyl, tert-butyl itaconate-isoamyl, tert-butyl-4-methyl-2-itaconate
Itaconic acid diester having a hydrocarbon group such as pentyl and tert-butyl-2-ethylhexyl itaconate; methyl- (trimethylsilyl) -itaconate, ethyl-
(Trimethylsilyl) -itaconate, isopropyl-
(Trimethylsilyl) -itaconate, cyclohexyl (trimethylsilyl) -itaconate, tert-butyl-
(Trimethylsilyl) -itaconate, isopropyl-
Itaconic acid diester having a siloxane-based hydrocarbon group such as [3-tris (trimethylsiloxy) silyl] propyl-itaconate, isopropyl-3-{(pentamethyl) disiloxanyl} propyl-itaconate; N, N
-Dimethylaminoethyl-isopropyl itaconate,
Heteroatoms such as tert-butyl-1-butoxy-2-propyl itaconate, 2-cyanoethyl-isopropyl itaconate, glycidyl-isopropyl itaconate, diethylphosphonomethyl-isopropyl itaconate, 2-methylthioethyl-isopropyl itaconate, etc. Containing itaconic acid diester; perfluorooctylethyl-isopropylitaconate, trifluoromethyl-isopropylitaconate, pentafluoroethyl-
Homopolymers or copolymers such as itaconic acid diester substituted with a halogen atom such as isopropyl itaconate, hexafluoroisopropyl-isopropyl itaconate, dihexafluoroisopropyl itaconate, bis-1-chloroisopropyl itaconate, or itacon Itaconic acid diester polymers obtained from copolymers of acid diesters and various copolymerizable monomers can be preferably used. In order to produce the itaconic acid diester polymer, it can be obtained by polymerization or copolymerization by a usual radical polymerization method. The reaction conditions for the polymerization or copolymerization are not particularly limited, but are preferably 0 to 100 ° C., and 2 to 3
The reaction is desirably performed within a range of 0 hours, and the molecular weight of the obtained itaconic acid diester polymer is 10,000 to 2,000,000.
It is preferred that Examples of the copolymerizable monomer include vinyl acetate, vinyl propionate, vinyl caproate, vinyl benzoate, styrene, α-methylstyrene, chloromethylstyrene, methyl vinyl ether,
Preferred examples include n-butyl ether, aliphatic or aromatic allyl ester, acrylic acid or methacrylic acid ester, acrylonitrile, vinyl chloride, vinylidene chloride, ethylene, butadiene, chloroprene, isoprene, isobutylene, and the like.

As the polymerization initiator, benzoyl peroxide, diisopropylperoxydi-carbonate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, tert-butylperoxydiisobutyrate, lauroyl peroxide, azobisisobutyl Butyronitrile and the like. The amount of the polymerization initiator used is preferably 10 parts by weight or less, more preferably 5 parts by weight or less based on 100 parts by weight of the raw material monomer.

In the itaconic acid diester polymer used in the present invention,
It is preferable to contain the itaconic acid diester repeating unit represented by the general formula (I) in an amount of 60 mol% or more. When the repeating unit of the itaconic acid diester in the polymer is less than 60 mol%, the rigid rod-like structure, which is the original property of the itaconic acid diester polymer, cannot be retained, and the polymer becomes a flexible structure. Because of the ball shape, it is difficult to form a uniform thin film by spin coating or coating,
Further, it is not preferable because it may be unstable both thermally and chemically.

In the present invention, to produce a thin film of the itaconic acid diester polymer, the itaconic acid diester polymer,
It can be obtained by spin coating in a specific rotation speed range. Specifically, for example, first, the itaconic acid diester polymer is dissolved in a vaporizable organic solvent to prepare a dilute solution of the itaconic acid diester. As the transpirable organic solvent, general-purpose organic solvents such as chloroform, methylene chloride, ethylene dichloride, benzene, toluene, 1,1,
2-trichloro-1,2,2-trifluoroethane and the like can be mentioned. Also, the solution concentration of the itaconic acid diester polymer, the itaconic acid diester polymer, 0.1 to 20 mg / m
Should be a solution containing, preferably 0.5 to 3 mg
By adjusting the content to the range of / m, a solution of the itaconic acid diester polymer can be obtained. Next, in order to make the itaconic acid diester solution into a thin film having a thickness of 10 to 1000 ° by a spin coating method on a liquid crystal substrate, the rotation speed of the spin coater needs to be 1000 to 15000. Also,
Although the film thickness slightly varies depending on the working temperature, under the above conditions, a desired polymer ultrathin film can be produced by spin coating at a working temperature of usually about 10 to 35 ° C.

In the present invention, as another method for producing an ultrathin film of the itaconic acid diester polymer, a solution containing a specific amount of the itaconic acid diester polymer is spread on a water surface, and then the surface pressure is maintained at a specific pressure. The solid film can be obtained by accumulating the solid film by a vertical immersion method or a horizontal deposition method. Specifically, for example, dissolving the itaconic acid diester polymer in a water-immiscible transpirable organic solvent to make a dilute solution of the itaconic acid diester,
Next, the itaconic acid diester solution is spread on the clean water surface to form a gas film. Examples of the transpirable organic solvent include general-purpose organic solvents such as chloroform, ethylene dichloride, benzene, and toluene.The diester polymer of itaconic acid is used as a dilute solution of these organic solvents and gently spreads on the water surface. I do. When developing on the water surface, it is necessary to pay attention to the concentration of the solution of the itaconic acid diester polymer and the type of the solvent. The concentration of the developing solution is 0.1 to 1
It is in the range of 0 mg / m, preferably in the range of 0.1 to 3 mg / m. When the solvent spreads on the water surface and the solvent is evaporated, a gas film having a surface pressure of 1 mN / m or less in which each molecule does not interact with each other is obtained. A pressure is applied to the gas film to be obtained as described above, for example, from the horizontal direction to reduce the surface pressure to 3
Keep at ~ 40mN / m to make a solid film state. The surface pressure to be set depends on the type of the itaconic acid diester polymer to be used, and a surface pressure-area (FA) isothermal curve is determined in advance, and a sharp rising portion of the FA curve corresponding to the solid film is obtained. It is preferable to set the surface pressure to. Next, by accumulating the solid film on a substrate by a vertical immersion method or a horizontal deposition method, a polymer ultrathin film can be produced.

In the present invention, the homogeneity and smoothness of the ultra-thin polymer film are affected by the state of the substrate surface, but it is sufficient if the mirror surface is such that no trace of polishing is observed by visual observation. Particularly useful and easy to accumulate as a substrate when forming various electric elements, Al, Si, Ge, Ni, Fe, Co,
Cu, Pt, Au, rare earth metals, metal oxides and metal oxide semiconductors such as SiO ₂ , NiO, SnO ₂ , In ₂ O ₃ , indium tin nesa glass (hereinafter abbreviated as ITO nesa), tin oxide nesa glass (hereinafter nesa) abbreviated) compounds such as semiconductor, for example, gallium arsenide, gallium phosphide, chalcogen such as indium phosphide, such as zinc selenide, transition metal selenides such as zinc sulfide, sulfides, WO ₃ based chalcogenides, VO ₂ based chalcogenides such as , Polycarbonate, polyethylene terephthalate, polyethylene, polypropylene and the like, but are not limited thereto.

<Effects of the Invention> Since the ultra-thin polymer film of the present invention contains the itaconic acid diester polymer as an essential component and can be obtained by a spin coating method or a Langmuir-Blowjet method, chemical stability, insulating properties and mechanical properties are improved. It has strong mechanical strength, and is used in various fields such as electrical elements (MIM, MIS, SIS), patterning (liquid crystal substrate (rubbing), microlithography), optical elements (optical waveguides, binder resin for nonlinear tertiary elements), etc. Application is possible.

<Examples> Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the invention is not limited by the examples.

Example 1 Various concentrations of poly (di-tert-butyl itaconate) (hereinafter
PDtBI) (1.2m / m chloroform solution 1m).
The solution was dropped on a 5 × 5 cm glass substrate, and spin-coated (rotation time: 80 seconds) to form an ultrathin film. The film thickness is measured by the stylus method (Sloan,
Dektak 11A). FIG. 1 shows the relationship between the film thickness and the number of rotations.

Examples 2-5 Instead of PDtBI of Example 1, poly (diisopropyl itaconate) (Example 2), poly (dicyclohexyl itaconate) (Example 3), and poly (dihexafluoroisopropyl itaconate) (Example) Example 4) and poly (dichloroisopropyl itaconate) (Example 5) were used to form an ultrathin film on a glass substrate under the conditions shown in Table 1. Table 1 shows the relationship between the conditions for forming the ultrathin film and the film thickness.

Example 6 A Teflon trough having an inner area of 15 × 50 cm ² and a depth of 2 cm was filled with pure water, and the room temperature was set at 20 ° C. Poly (diisopropyl itaconate) at a concentration of 0.5 mg / m (hereinafter abbreviated as PDiPI)
Gently pour 100 μl of the chloroform solution onto the surface of the water,
The solvent was evaporated. While detecting the surface pressure, the 20 cm long Teflon barrier installed on the trough is translated at a speed of 5 mm / min to reduce the area, and the relationship between the surface pressure and the molecular occupied area (FA curve) I asked. Figure 2 shows the PDiRI FA
The curve is shown. From this curve, it was found that a surface pressure of 5 to 40 mN / m which shows a sharp rise is appropriate for the accumulation of the LB film. An LB film was formed at a surface pressure of 20 mN / m, and 39 ultra-thin polymer films were formed on a glass substrate by accumulating 39 layers vertically on a glass substrate. Table 2 shows the surface pressure, the number of layers, and the film thickness.

Examples 7-10 Instead of PDiPI of Example 6, poly (di-titaconate)
ert-butyl) (Example 7), poly (dicyclohexyl itaconate (Example 8), poly (dichloroisopropyl itaconate) (Example 9) and poly (dihexafluoroisopropyl itaconate) (Example 10). ) Was formed at a constant surface pressure in the same manner as in Example 6 under the conditions shown in Table 2 and then accumulated on a glass substrate by a vertical immersion method to produce a polymer ultrathin film. Cumulative surface pressure,
The cumulative number of layers and the film thickness are shown respectively.

Example 11 After forming an LB film of PDiPI in the same manner as in Example 6,
An ultra-thin polymer film was accumulated on a glass substrate by a horizontal deposition method. Table 2 shows the surface pressure, the number of layers, and the film thickness.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the number of revolutions of a spin coater performed in Example 1 and the thickness of the ultra thin polymer film of the present invention. FIG. 2 is a graph showing a surface pressure-area curve at 20 ° C. of a diisopropyl itaconate polymer prepared in Example 6.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Yamada 1-7-35-6 Uenodai, Kamifukuoka-shi, Saitama (56) References JP-A-2-173080 (JP, A) JP-A-62-262772 ( JP, A) JP-A-59-143615 (JP, A) JP-A-63-16071 (JP, A) JP-A-3-291933 (JP, A) JP-A-3-291632 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) C08J 5/18 C08F 22/14

Claims (3)

(57) [Claims] An ultra-thin polymer film having a film thickness of 10 to 1000 mm formed by spin-coating or Langmuir blow-jet (LB) method, wherein said itaconic acid diester polymer is And the following general formula (I) (Wherein, R ₁ and R ₂ represent identical or different radicals, R ₁
And at least one of R ₂ is a branched alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituted alkyl having 2 to 6 carbon atoms having a substituent having a ring structure having 3 to 14 carbon atoms. Represents a substituted cycloalkyl group having 3 to 10 carbon atoms or a siloxane-based hydrocarbon group having a substituent of the above-mentioned ring structure, and each of the groups may contain a hetero atom, and may be substituted with a halogen atom. Or a repeating unit of itaconic acid diester represented by the formula (1): 2. The method according to claim 1, wherein the solution containing 0.1 to 20 mg / m of the itaconic acid diester polymer according to claim 1 is formed into a thin film by a spin coating method at a rotation speed of 1,000 to 15,000. A method for producing an ultra-thin polymer film. 3. A solution containing 0.1 to 3 mg / m of the itaconic acid diester polymer according to claim 1 is spread on a water surface, and then pressure is applied to keep the surface pressure at 3 to 40 mN / m to obtain a solid film state. 2. The method according to claim 1, wherein the solid film is obtained by an LB method in which the solid film is accumulated by a vertical immersion method or a horizontal deposition method.