JPH03157163A - Very thin polymer film and its production - Google Patents

Abstract

PURPOSE:To improve the chemical stability and heat resistance of a very thin polymer film of 10-1,000Angstrom thickness by forming the film by spin coating or the Langmuir-Elodgett's technique with a methacrylic ester polymer contg. repeating units of specified methacrylic ester. CONSTITUTION:A soln. contg. 0.1-20mg/C methacrylic ester polymer having repeating units of methacrylic ester represented by formula I (where R is 3-12C branched alkyl, 3-12C cycloalkyl, 2-6C substd. alkyl having 3-14C cyclic substituents, etc.) is prepd. and applied by spin coating at 1,000-15,000 rotational frequency to form a very thin polymer film of 10-1,000Angstrom thickness. This film has superior chemical stability, insulating property and mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ultra-thin polymer film and a method for manufacturing the same, and more particularly to electric devices (MIM, MIS, etc.).

The present invention relates to ultra-thin polymer films used in fields such as SIS, TFT), patterning (liquid crystal substrates (rubbing treatment), microlithography), optical elements (optical waveguides, binder resins for nonlinear tertiary elements), and methods for producing the same.

<Prior Art> Conventionally, ultrathin polymer films used for electrical elements, patterning, optical elements, etc. have uniform molecules. One of the methods for producing ultra-thin polymer films that are smooth and homogeneous is the Langmuir-Prodgett method (hereinafter abbreviated as LB method).

In the LB method, organic molecules are made into a dilute solution of an organic solvent and then spread on a clean water surface, and the gas film that remains after the solvent evaporates is compressed in the plane direction to form a solid film in which the molecules are densely backed. This is a method in which a solid film is transferred and accumulated on the surface of a solid substrate, and the thin film formed on the substrate is called an LB film (for example, in the literature,
B, Blodgatt, J, Am, Chew.

Soc, 55.1007 (1935)),
[K, Fukuda et al.

J, Co11oid Interface Sci,
54.430 (1976)].

The feature of the LB film is that it can be made from an ultra-thin film on the molecular order to a cumulative film of any thickness by repeated lamination, and is a smooth and homogeneous film with uniform molecular orientation. Therefore, LB films are expected to be used as materials for various electronics, and are suitable for use with linear fatty acids having 16 or more carbon atoms or their alkaline earth metal salts.

LB film formation of cadmium salts has been widely studied [for example, Kiyonari Fukuda, Hiroo Nakahara (co-author), Chemistry Review 40
Molecular Assembly〉p82-104゜1983, and its literature. However, the LB film of these fatty acids or their metal salts has a high mechanical strength.

It has the disadvantage that it has poor heat resistance and is not practical. Therefore, methods have been devised in which polymerizable fatty acids are formed into an LB film and then subjected to polymerization treatment, or where polymerizable fatty acids are polymerized on the water surface and then formed into an LB film (reference, ibid.). Severe twitching and crack formation makes transfer to the substrate extremely difficult.

On the other hand, it is possible to create an LB film using a polymer and accumulate it on a substrate, but general polymers have a thread-like aggregated state even in dilute solutions. When deployed on the water surface, it does not become a gas film, and the L
It is difficult to form a B film, and it has been reported that by exceptionally using polypeptide or polyitaconate, the polymer chains take a rod-like structure and create a LB film [References J, H
.

McAlear et al., Symposium on VLS
I Technology.

Digest of Tech, Paper, 82
(1981), Shigehara et al., J.A.
mer, Chem, Soc,, 1237. Vo
l, 109° (1987)].

Furthermore, attempts have been made to spin-coat a synthetic polymer solution onto a substrate in order to provide a #@edge layer on various devices, but the performance required for the insulating layer is that the heat resistance is at least It must be 200℃ or higher, thermally and chemically stable, and have excellent moisture resistance and mechanical and electrical properties.There are only a limited number of polymers that meet these requirements, such as polyimide. , polyether sulfone, polyphenylene sulfide, polysulfone, polyphenylene oxide, polyethylene terephthalate, etc. are known. These polymers are dissolved in an organic solvent to create a dilute solution, which is spin-coated onto a substrate and then the solvent is evaporated to form an insulating film. Since polar solvents such as dimethylacetamide and N-methylpyrrolidone are high boiling point solvents, their evaporation rate is slow and there is a high possibility that they remain in the insulating film. Furthermore, the viscosity of polymer solutions is relatively high, and the current situation is that considerable technology is required to create a uniform and smooth film.

<Problems to be Solved by the Invention> An object of the present invention is to provide an ultra-thin polymer film that is mechanically and chemically stable and heat resistant, and a method for producing the same.

<Means for Solving the Problems> According to the present invention, a methacrylic acid ester polymer is coated using a spin coating method or Langmuir-Blowgett (L
B) An ultra-thin polymer film with a film thickness of 10 to 100·O formed by the method, wherein the methacrylic acid ester polymer has the following general formula (1) (wherein R is a carbon number of 3 to 12 a branched alkyl group, a cycloalkyl group having 3 to 12 carbon atoms, and a substituent having a ring structure having 3 to 14 carbon atoms.
6 substituted alkyl group, a substituted cycloalkyl group having 3 to 1 o carbon atoms or a siloxane hydrocarbon group having a substituent in the ring structure, and each of the above groups may contain a heteroatom, There is also provided an ultra-thin polymer film characterized by containing a repeating unit of methacrylic acid ester (which may be substituted with a halogen atom).

Further, according to the present invention, a solution containing 0.1 to 20 mg/mQ of the methacrylic acid ester polymer is heated at a rotational speed of 100.
A method for producing an ultra-thin polymer film is provided, which is characterized in that the film is made into a thin film using the spin knee 1-method in the range of 0 to 15,000.

Further, according to the present invention, a solution containing 0.1 to IQ mg/mQ of the methacrylic acid ester polymer is spread on the water surface, and then pressure is applied to maintain the surface pressure at 3 to 30 mN/m to form a solid film. Provided is a method for producing an ultra-thin polymer film, characterized in that the solid film is deposited by a vertical dipping method or a horizontal deposition method.

The present invention will be explained in more detail below.

In the present invention, a methacrylic ester polymer containing repeating units of methacrylic ester represented by the following general formula (1) is used. In the formula, R is a branched alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a substituted alkyl group having 2 to 6 carbon atoms having a substituent having a ring structure having 3 to 14 carbon atoms, or the ring structure described above. represents a substituted cycloalkyl group having 3 to 10 carbon atoms or a siloxane hydrocarbon having a substituent. Even if the branched alkyl group, the cycloalkyl group, the substituted alkyl group, the substituted cycloalkyl group, and the siloxane hydrocarbon group contain a heteroatom such as a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, etc. It may also be substituted with a halogen atom.

Polymers of methacrylic acid esters having repeating units represented by the general formula (1) include, for example, isopropyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, adamantyl methacnolate, and 4-methyl-2-methacrylate. Methacrylic acid esters having a hydrocarbon group such as pentyl; Methacrylic acid esters having a siloxane hydrocarbon group such as (trimethylsilyl) methacrylate, 3-tris(trimethylsiloxy)silylpropyl methacrylate, and 3-((pentamethyl)disiloxanyl)propyl methacrylate. ; methacrylic acid ester containing a hetero atom such as 1-butoxy-2-propyl methacrylate, 2-cyanoethyl methacrylate, glycidyl methacrylate, diethylphosphonomethyl methacrylate, 2-methylthioethyl methacrylate; perfluorooctylethyl methacrylate;
Homopolymers or copolymers of methacrylic acid esters substituted with halogen atoms, such as trifluoromethyl methacrylate, pentafluoroethyl methacrylate, hexafluoroisopropyl methacrylate, 1-chloroisopropyl methacrylate, or various copolymers with methacrylic esters. A methacrylic acid ester polymer obtained by copolymerization with a polymerizable monomer can be preferably used. A methacrylic acid ester polymer having a repeating unit of methacrylic acid ester represented by the general formula (I) can be produced by polymerization or copolymerization using a conventional radical polymerization method. The reaction conditions for the polymerization or copolymerization are not particularly limited, but it is preferable to carry out the reaction at 0 to 100°C for 2 to 30 hours. Molecular weight is 10000~200o
ooo is preferable. Examples of the copolymerizable monomer include vinyl acetate, vinyl propionate, vinyl caproate, vinyl benzoate, styrene, α-methylstyrene, chloromethylstyrene, methyl vinyl ether, n-butyl ether, aliphatic or aromatic allyl ester. , acrylic acid or methacrylic acid ester, acrylonitrile, vinyl chloride, vinylidene chloride, ethylene,
Preferred examples include butadiene, chloroprene, isoprene, isobutylene, and the like.

Examples of polymerization initiation catalysts include benzoyl peroxide, diisopropyl peroxycarbonate L-butyl peroxy-2-ethylhexanoate, tret-butylperoxypivalate, tret-butylperoxydiisobutyrate, lauroyl peroxide, azobisisobutyroyl Examples include nitrile. The amount of the polymerization initiator used is preferably 10 parts by weight or less per 100 parts by weight of the raw material monomer,
More preferably, it is 5 parts by weight or less.

The methacrylic ester polymer used in the present invention preferably contains 60 mol% or more of the repeating unit of the methacrylic ester represented by the general formula (1). If the repeating unit of methacrylic acid ester in the polymer is less than 60 mol%, the rigid rod-like structure, which is the original property of the methacrylic acid ester polymer, cannot be maintained and it becomes stringy in the polymer solution. It is difficult to form a uniform thin film by spin coating or LB method, and it is also thermally difficult.

It is not preferable because it may become chemically unstable.

Furthermore, it is difficult to produce the thin film itself, and the uniformity decreases, which is undesirable.

In the present invention, an ultra-thin film of a methacrylic ester polymer can be produced by spin coating a solution containing a specific amount of the methacrylic ester polymer at a specific rotation speed. Specifically, for example, first, the methacrylic ester polymer is dissolved in a transpirationable organic solvent to prepare a dilute solution of the methacrylic ester. As the evaporative organic solvent, general-purpose organic solvents such as chloroform, ethylene dichloride, benzene, toluene,
, 1,2-trichloro-1,2,2-trifluoroethane and the like. In addition, the solution concentration of methacrylic acid ester polymer, methacrylic acid ester polymer,
The solution must contain 0.1 to 20 mg/mQ,
Preferably, by adjusting the amount in the range of 0.5 to 3 mg/mQ, a solution of the methacrylic acid ester polymer can be obtained.

Next, in order to form an ultra-thin film with a thickness of 10 to 1000 by spin coating the solution of the methacrylic acid ester polymer, the rotational speed of the spin coater is set to 1000 to 150.
It needs to be set to 00. In addition, the film thickness varies slightly depending on the working temperature, but under each of the above conditions, it is usually 10 to 10.
A desired ultra-thin polymer film can be produced by spin coating at an operating temperature of about 35°C.

In addition, in the present invention, as another method for producing an ultra-thin film of methacrylic acid ester polymer, after spreading a solution containing a specific amount of methacrylic acid ester polymer on the water surface,
The surface pressure can be maintained at a specific pressure and the solid film state can be obtained by accumulating the solid film by a vertical dipping method or a horizontal deposition method. Specifically, for example, a methacrylate ester polymer is dissolved in a water-immiscible evaporative organic solvent to create a dilute solution of the methacrylate ester polymer, and then the methacrylate ester solution is spread on the surface of clean water. Forms a gas film. As the transpirationable organic solvent, general-purpose organic solvents such as chloroform, ethylene dichloride,
Examples include benzene, toluene, etc., and the methacrylic acid ester polymer is made into a dilute solution of these organic solvents,
Spread quietly on the water surface. When deploying on the water surface,
It is necessary to pay attention to the concentration of the methacrylic acid ester polymer solution and the type of solvent. The concentration of the developing solution is 0
．． It ranges from 1 to IQmg/-, preferably 0.1
~3 mg/mQ. When it is spread on the water surface and the solvent is evaporated, a gas film with a surface pressure of 1 mN/m or less is obtained in which the molecules do not interact with each other. Pressure is applied, for example, from the horizontal direction to the gas film obtained as described above, and the surface pressure is maintained at 3 to 30 mN/m to form a solid film state. How much surface pressure to set depends on the type of methacrylate ester polymer used. Obtain a preliminary surface pressure-area (FA) isotherm curve, and then calculate the sharpness of the FA curve corresponding to the solid film. It is preferable to set the surface pressure to the surface pressure of the rising portion. Next, the obtained solid film can be deposited on a substrate by a vertical dipping method or a horizontal deposition method to produce an ultra-thin polymer film.

In the present invention, the homogeneity and smoothness of the ultra-thin polymer film are affected by the condition of the substrate surface, but it is sufficient that the mirror surface has no polishing marks when observed with the naked eye.

Examples of materials that are particularly useful and easy to accumulate as substrates when forming various electric elements include Al, Si, Ge, and Ni.
, Fe, Co.

Cu, Pt, Au, rare earth metals, metal oxides and metal oxide semiconductors such as Sin, Ni○.

Compound semiconductors 1 such as SnO2, In201, indium tin nesa glass (hereinafter abbreviated as IT○nesa), tin oxide nesa glass (hereinafter abbreviated as nesa), etc. For example, gallium arsenide,
Chalcogens such as gallium phosphide and indium phosphide; transition metal selenides such as zinc selenide and zinc sulfide;
Examples include sulfide, W○, chalcogenide, vO2 chalcogenide, polycarbonate, polyethylene terephthalate, polyethylene, and polypropylene.

It is not limited only to these.

<Effects of the Invention> The ultra-thin polymer film of the present invention has a methacrylic acid ester polymer as an essential component and is obtained by a spin coating method or a Langmuir-Blowgett method. It has high strength and is suitable for various electrical elements (MIM.

MIS, SIS, TFT), patterning (liquid crystal substrate (
It can be applied to fields such as rubbing treatment), microlithography), optical elements (optical waveguides, binder resin for nonlinear tertiary elements), etc.

<Examples> The present invention will be explained in more detail with reference to Examples below, but the scope of the invention is not limited by the Examples.

poly(tert-butyl methacrylate) (
1 mQ of a chloroform solution of PtBMA (hereinafter abbreviated as PtBMA),
Drop onto a 2.5 x 5 cm glass substrate and spin coat (
The rotation time was 80 seconds) to create an ultra-thin film. The film thickness was determined by the eroded needle method (Sloan, Dec-TacllA). Figure 1 shows the relationship between film thickness and rotation speed.

For Senniwa disaster, poly(cyclohexyl methacrylate) (Example 2), poly(cyclohexyl methacrylate) (Example 3), and poly(hexafluoroisopropyl methacrylate) (execution example) were used instead of PtBMA in Example 1. Example 4) and poly(chloroisopropyl methacrylate) (Example 5) were used to form ultrathin films on a glass substrate under the conditions shown in Table 1. Super Table 1 38 bottles...1,1,2-trichloro-1,2,2-trifluoroethane] 11 Shonai area 15 x 50a (, 2cm deep Teflon bowl roughly filled with pure water, heated to room temperature for 20' It was set to C.

A chloroform solution of poly(isopropyl methacrylate) (hereinafter abbreviated as PiPMA) with a concentration of 0.5 mg/mQ
μm was gently dropped onto the water surface and the solvent was allowed to evaporate. 20cm long installed on the trough while sensing surface pressure
The relationship between surface pressure and molecule occupied area (
FA curve) was determined. FIG. 2 shows the FA curve of PiPMA. From this curve, it was found that a surface pressure of 5 to 20 mN/m, which shows a rapid rise, is appropriate for the accumulation of the LB film. An LB film was formed at a surface pressure of 15 mN/m, and 49 layers were accumulated on a glass substrate by a vertical dipping method to create an ultra-thin polymer film on the substrate. Table 2 shows the surface pressure, calendar number, and film thickness.

In place of PiPMA in Example 6, poly(tert-butyl methacrylate) (Example 7), poly(cyclohexyl methacrylate) (Example 8), and poly(chloroprene methacrylate) (Example 8) were used instead of PiPMA in Example 6. Example 9) and poly(hexafluoroisopropyl methacrylate) (Example 10) were used to form an LB film at a constant surface pressure in the same manner as in Example 6 under the conditions shown in Table 2. Table 2 shows the surface pressure,
Calendar number and film thickness are shown respectively.

After forming a PiPMA LB@ in the same manner as in Example 6, it was deposited on a glass substrate by the horizontal deposition method.

An ultra-thin polymer film was produced by accumulating the results. Table 2 shows the surface pressure, number of layers, and film thickness.

People - 11 miles

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the rotation speed of the spin coater used in Example 1 and the film thickness of the ultra-thin polymer film of the present invention. FIG. 2 is a graph showing the surface pressure-area curve at 20°C of the isopropyl methacrylate polymer obtained in Example 6. Figure 1 Patent applicant

Claims (1)

[Scope of Claims] 1) An ultra-thin polymer film with a thickness of 10 to 1000 Å formed by forming a methacrylic acid ester polymer by a spin coating method or a Langmuir-Blowgett (LB) method, the polymer film having a thickness of 10 to 1000 Å; The polymer has the following general formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼... (I) (In the formula, R is a branched alkyl group having 3 to 12 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms. group, a substituted alkyl group having 2 to 6 carbon atoms having a substituent having a ring structure having 3 to 14 carbon atoms,
Represents a substituted cycloalkyl group or siloxane-based hydrocarbon group having 3 to 10 carbon atoms having a substituent in the ring structure, each of the groups may contain a hetero atom, and is not substituted with a halogen atom. An ultra-thin polymer film characterized by containing a repeating unit of methacrylic acid ester represented by 2) 0.1 methacrylic acid ester polymer according to claim 1
A solution containing ~20 mg/ml was heated at a rotation speed of 1000 to 15
2. The method for producing an ultra-thin polymer film according to claim 1, wherein the thin film is formed by spin coating to a range of 0.000000. 3) 0.1 methacrylic acid ester polymer according to claim 1
After spreading a solution containing ~10 mg/ml on the water surface,
The production of the ultra-thin polymer film according to claim 1, wherein pressure is applied to maintain the surface pressure at 3 to 30 mN/m to form a solid film, and the solid film is accumulated by a vertical dipping method or a horizontal deposition method. Method.