JPH0678423B2 - Electropolymerization film formation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming an electropolymerized film of an organic polymer on an insulating oxide. The organic polymer formed on the insulating oxide can be effectively used as a material for electronic devices.

2. Description of the Related Art As a conventional method for forming an electrolytically polymerized film on an insulating oxide, there is one as shown in FIG. That is, the electrodes 4 are arranged on the insulating substrate 3 at intervals of 1 mm or less, and electrolytic polymerization is performed. As shown in FIG. 3, with this electrode 4 as an anode, a large oxidation current is passed to carry out electrolytic polymerization. By carrying out this electrolytic polymerization for a long time, the chains of the organic polymer also start to grow in the lateral direction, and when the anodic oxidation polymerization is further advanced for a long time, a short circuit is finally generated and the organic polymer chains are deposited on the insulating substrate 3 as shown in FIG. To start. It is possible to stack an organic polymer on the insulating substrate 3 by this method. However, the obtained organic polymer film is not smooth and non-uniform, and does not have sufficient mechanical strength.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to obtain an organic polymer film which is smooth and uniform and has a sufficient mechanical strength directly on an insulating film.

Means for Solving the Problems An oxidation polymerization and a reduction potential are alternately and periodically applied to the insulating oxide so as to intercalate a cation, and an electrolytically polymerized film is formed on the insulating oxide. .

The organic polymer film obtained by periodically applying the reduction potential of the insulating oxide (reverse bias of polymerization) during electrolytic polymerization for a certain period of time has a smooth, dense, and high mechanical strength. It becomes possible to stack an excellent organic polymer film on the insulating film.

EXAMPLES Hereinafter, the present invention will be described in the case of using tungsten oxide (hereinafter referred to as WO ₃ ) as an insulating film on an electrode.

That is, an electrode coated with an insulating film is put into an electrolytic solution (dissolving an electrolyte and a monomer capable of electrolytic polymerization in a polar solvent) to carry out electrolytic polymerization. In the case of positive bias (the electrode coated with the insulating film is the anode), no current flows. When a reducing potential of WO ₃ is applied cyclically as a reverse bias for a certain period of time, a current flows at the time of positive bias and electrolytic polymerization proceeds to stack an organic polymer film on the insulating film.

WO ₃ is reduced as shown in Formula 1 when a reverse bias is applied (FIG. 1 (A)) (M ⁺ is hydrogen, lithium, sodium,
Indicates a monovalent cation such as potassium. ).

WO ₃ + M ⁺ + e → MWO ₃ ... 1 The generated MWO ₃ becomes electronically conductive.

Next, when positively biased, MWO ₃ is oxidized as shown in Equation 2 (FIG. 1 (B)).

MWO ₃ → WO ₃ + M ⁺ + e ... 2 When positive bias is applied, electrons are extracted from MWO ₃ , and the film changes from electron conductivity to an insulator. At this time, there is a time delay in the reaction, and while maintaining the electronic conductivity, the MW
Electrons are withdrawn from the monomer on the O ₃ film surface, and the electron-withdrawn monomer associates and polymerizes on the WO ₃ film surface. as a result,
An organic polymer film which is smooth and dense and has high mechanical strength can be laminated on the insulating film.

As the insulating oxide film to which the present invention can be applied, in addition to WO ₃ , molybdenum oxide (MoO ₃ ), titanium oxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₃ ), silicon oxide (SiO ₂ ), All intercalatable oxides such as vanadium oxide (V ₂ O ₅ ) can be mentioned. This insulating oxide film is formed by thermal oxidation method, resistance heating vapor deposition method, sputter vapor deposition method, electron beam vapor deposition method, plasma deposition method, pyrolysis vapor deposition method, photolysis vapor deposition method, electrolytic oxide film formation. Any method such as the law is effective. Further, as the monomer to which the present invention can be applied, all the monomers which can be electrolytically polymerized, but the following are specific examples. That is, five-membered ring compounds such as pyrrole, thiophene, N-methylpyrrole, 3-methylthiophene and naphthothiophene, aniline,
Examples thereof include aromatic compounds represented by phenol and the like, and vinyl groups such as dibenzocrown ether and vinylpyridine.

Examples will be described below.

Example 1 Tungsten oxide of 2000 Å was formed on the electrode as an insulating film by an electron beam evaporation method. Next, an electrolytic solution prepared by mixing 1.0 g of pyrrole, 1.2 g of borofluoride and 100 ml of acetonitrile was placed in an electrolytic bath, and a platinum plate was used as a cathode and a silver wire was used as a reference electrode. An electrode having the above-mentioned insulating film attached to the anode was used. 0 for the reference electrode as a positive bias.
Apply 68V for 2 seconds and reverse bias of -0.5V for 2 seconds,
Electropolymerization was carried out for 2 hours. Next, the laminated film was washed with acetonitrile and then with water to remove unreacted monomers and the electrolyte.

Examples 2 to 8 The following are performed using various insulating films instead of the tungsten oxide used as the insulating film in Example 1.

The organic polymer could be laminated on the insulating film, and the resulting film was smooth, dense, and had sufficient mechanical strength.

Effect of the Invention By using an electrolytic polymerization method for an insulating film, it is possible to directly stack an organic polymer that is smooth, dense and has sufficient mechanical strength. Therefore, the organic polymer forming method can be used for manufacturing an electronic device such as a transistor having an insulator interposed therebetween, and thus these devices can be formed extremely easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an insulating film coating in one embodiment of the present invention, FIG. 1 (A) is a diagram showing the movement of electrons when a reverse bias is applied, and FIG. 1 (B) is a view when a positive bias is applied. FIG. 2 is a diagram showing the movement of electrons, FIG. 2 is a perspective view showing a conventional electrode,
FIG. 3 is a sectional view showing the operation of the conventional example. 1 ... Electrode, 2 ... Insulating film.

Claims (1)

[Claims] 1. When forming an electrolytically polymerized film on an insulating oxide, a cation is intercalated into the insulating oxide. A method for forming an electropolymerized film, which comprises applying and electrolytically polymerizing.