JPS62271409A - Organic thin film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a capacitor constructed using organic materials for both electrodes and dielectric material. This invention relates to a thin film capacitor formed by a monolayer deposition method.

[Conventional technology]

Traditionally, inorganic materials have been used extremely often as materials for circuit elements.
The use of organic materials has been limited to insulators and dielectrics. Among passive elements such as resistors and capacitors necessary for configuring electronic circuits, there have conventionally been two main methods for forming thin film capacitors using inorganic materials.

(1) A dielectric thin film such as silicon oxide or metal oxide is formed on a metal thin film by a method such as vacuum evaporation or reactive sputtering, and a metal thin film is further formed on this.

(2) The surface of the metal thin film formed by vacuum evaporation is oxidized to form a dielectric layer, and a metal electrode is formed on this.

[Problem that the invention seeks to solve]

However, the method of forming an inorganic material as a dielectric layer by vacuum evaporation or reactive sputtering is not necessarily an easy method.

Incidentally, in recent years, research on organic materials has been actively conducted, and materials that exhibit metallic conductivity in a single-crystal state and substances that exhibit superconductivity at extremely low temperatures have been reported. Furthermore, there have been reports of substances exhibiting properties as double conductors, and we have reached a situation where various electrical properties can be realized only with organic substances.

Specifically, in recent years, tetracyanoquinodimethane (TCNQ)
) is an organometallic compound with bis-tetracyanoquinodimethane docosylpyri as an electron acceptor, and an amphiphilic charge transfer complex with a long-chain alkyl group as a hydrophobic moiety forms a monomolecular film on the water surface. It has been reported that a monomolecular cumulative film can be created by accumulating the monomolecular film layer by layer (Insulating Materials and Electronic Materials Joint Research Group Materials 1985/I
t/15P, 29). The monomolecular cumulative film has a large electrical conductivity of 0.157 cm in the direction parallel to the film surface, while the electrical conductivity in the direction perpendicular to the film is about 10-''S/cm, indicating that it behaves as an insulator. It has been observed.

The above monomolecular cumulative film is produced using the Langmuir-Blodgett method (
LB method: New Experimental Chemistry Course, Chapter 18, pages 498-507,
Maruzen Publishing). The principle of this method is as follows.

In other words, if a molecule that has both a parent wood group and a hydrophobic group spreads on the water surface and increases its areal density appropriately, if the balance between hydrophilicity and hydrophobicity is appropriate, the parent wood group will form on the water surface. A monomolecular film is formed with the hydrophobic groups facing downward and the hydrophobic groups facing upward.

In other words, such molecules behave as a two-dimensional particle system,
When the areal density of molecules is low, a two-dimensional ideal gas equation of state holds true between the area per molecule (molecular occupied area) and the surface area, creating a "gas film", which increases the surface pressure and reduces the areal density of molecules. Increasing the value increases the interaction between molecules, resulting in a two-dimensional solid "condensed film (or solid film)". In this state, the molecules are neatly arranged and oriented, and have a high degree of order and uniformity.

The aggregated film thus formed can be transferred to a substrate such as glass, and a monomolecular cumulative film can be obtained by stacking and transferring the monomolecular film multiple times onto the same substrate. The methods of transferring to the substrate include the vertical attachment method, horizontal attachment method,
A rotating drum method is known.

The L8 method is a thin film forming method under normal temperature and normal pressure, and is characterized in that the cumulative film thickness can be controlled by the number of times of accumulation.

Furthermore, the formation of a PN junction semiconductor in a monomolecular cumulative film using a composite system of a triphenylmethane dye monomolecular film has been reported.

The present invention was made in view of the above circumstances, and its purpose is to provide an organic thin film capacitor in which both the dielectric layer and the conductive layer are made of inorganic materials, and the method for forming the same is simple. be.

[Means for solving problems]

The above objects of the present invention are achieved by the present invention as follows. That is, the present invention provides a conductive layer containing a monomolecular film of organic molecules having both hydrophilic sites and hydrophobic sites or a cumulative film thereof, and an organic molecule having both hydrophilic sites and hydrophobic sites on a substrate. An organic thin film capacitor in which dielectric layers containing single molecules or cumulative films thereof are laminated and have two lead-out electrodes, each of the conductive layers being alternately connected to different lead-out electrodes. This is an organic thin film capacitor.

An embodiment of the invention is illustrated in FIGS. 1 and 2.

In the figure, 1 is a conductive layer, 2 is a dielectric layer, 3 is a conductive layer, 4 and 5 are extraction electrodes for accumulating electric charge or taking out the accumulated electric charge, and the conductive layer 1
．． The conductive layer 1 is connected to the take-out electrode 5 and the conductive layer 3 is connected to the take-out electrode 4 so that each of the conductive layers 1 and 3 becomes a different electrode alternately, and 6 is a glass substrate, and the conductive layer 1.3 and the dielectric layer are connected to each other. 2 are each formed by the LB method.

Since a capacitor is formed in which the conductive layers serve as opposing electrodes as described above, the capacitance is determined by the area of the opposing conductive layers,
It is determined by the distance between opposing conductive layers and the dielectric constant of the material used for the dielectric layer, and the dielectric strength voltage is determined by the distance between the conductive layers and the material used for the dielectric layer. The distance between the conductive layers can be changed by changing the number of cumulative layers of the dielectric cumulative film.

In the present invention, the organic substance used for the conductive layers 1 and 3 is an amphipathic substance having both hydrophilic sites and hydrophobic sites, such as an organometallic compound disclosed in JP-A No. 60-246357. can be used.

In the present invention, the organic substance used for the dielectric layer 2 is an amphipathic substance having both hydrophilic and hydrophobic sites, such as long-chain fatty acids (e.g., 616-C2° saturated,
unsaturated fatty acids) can be used.

An apparatus for producing the organic thin film capacitor of the present invention is shown in Figures 3a and 3b.

In the figure, 7 is a surface pressure gauge, which is connected to a surface control device 8 to control the movement of the movable barrier 9 to maintain a constant surface pressure. IO is an aqueous phase, which is pure water or water containing metal ions. 11 is a film forming substrate, and 12 is a film forming substrate holder which can be moved up and down.

A device as described above is operated as follows.

First, the liquid surface is cleaned, and a solution of conductive or dielectric molecules dissolved in a solvent such as benzene, chloroform, andandhryl-benzene (1:1) is dropped onto the liquid surface.
Forms a gas film. Next, the moving barrier 8 is gradually moved to the left to gradually reduce the area of the liquid surface where the molecules are spread, thereby increasing the areal density and forming a solid film. The state of this monomolecular film is detected by measuring the surface pressure of the monomolecular film spread on the liquid surface using a surface pressure sensor 13.

The horizontal movement of the movable barrier 9 is controlled based on the measured value of this surface pressure sensor. Generally, the surface pressure of a monomolecular film suitable for transferring to the film-forming substrate 11 is 15 to 30 dy.
n/cm, but the above range is only a rough guideline, as a suitable surface pressure value may be outside the above range depending on, for example, the chemical structure and temperature conditions of the membrane constituents.

By moving the film-forming substrate 11 up and down under the above conditions, the monomolecular film that has become a solid film can be attached to the surface of the substrate and transferred. Furthermore, a monomolecular cumulative film can be obtained by stacking and transferring a monomolecular film a plurality of times onto the same film-forming substrate 11.

The vertical movement of the film forming substrate 11 is usually 0.1-1 cm/
This is done at a speed of min.

When the film-forming substrate II is hydrophilic, the monomolecular film is formed as shown in Fig. 4a~
It is transferred as shown in Figure 4C.

That is, when the film-forming substrate 11 is raised from below the liquid level as shown in FIG. and then transferred. Next, when the film-forming substrate 11 is lowered, the second layer monomolecular film is deposited on the first layer with the hydrophobic sites 17 of the film constituent molecules facing the substrate 11, as shown in FIG. 4b.
It attaches to the single molecules of the layer and is transferred. When the film-forming substrate 11 is raised again, the third layer of monomolecular film is transferred as shown in FIG. 4C, and is subsequently accumulated in the same manner.

By the way, as mentioned above, the monomolecular film on the liquid surface is deposited on the film-forming substrate 1.
1, the surface density of molecules on the liquid surface decreases in accordance with the amount transferred to the film forming substrate 11, and the surface pressure also decreases. If this is left unattended, the monomolecular film on the liquid surface may no longer be able to maintain its solid film state, making it impossible to transfer it to the substrate 11. Therefore, even during the operation of transferring the monomolecular film to the substrate 11, the horizontal movement of the moving barrier 9 is controlled by the pressure sensor 13, so that the surface pressure of the monomolecular film on the liquid surface can be maintained at a predetermined constant pressure. I'm trying to do it now. That is, the movable barrier 9 responds to minute increases and decreases in the surface pressure measured by the pressure sensor, and is moved left and right by an amount that cancels out the slight increase or decrease in surface pressure.

The thickness of each of the conductive layer and the dielectric layer is 50 to 2 layers, more preferably 90 to 5000 layers.

〔Example〕

Specific examples of the present invention are listed below.

Example 1 A capacitor of the simplest construction as shown in Figure 1 was formed using an apparatus as shown in Figure 38.3b.

As a constituent molecule of conductive layers 1 and 3, bis-tetracyanoquinodimethanetocosylpyridium was dissolved in a 1:1 mixed solvent of acetonitrile and benzene at a concentration of IB/ml, and then adjusted to p) 16.8 with XHCO3. CdCl2
Concentration 4 x 10-' mol/1. 3rd water temperature 17℃
It was developed on the aqueous phase of the apparatus shown in Figure a.

After the solvents acetonitrile and benzene were removed by evaporation, the surface pressure was increased to 20 dyn/cm to form a monomolecular film. A clean glass substrate (IOIIIIIIIX 3
0mm) was gently immersed in 2011Iffi at a speed of 3mm/min in the direction across the water surface, and again at a speed of 3mm/ll1.
The conductive layer 1 was formed by gently pulling up the conductive layer by 20 mm+ by inclining and stacking three monomolecular films.

Next, after cleaning the water surface, a solution of alaxinic acid in chloroform with a concentration of 1 mg/ml was developed on the water phase, and after evaporating the chloroform, the surface pressure was adjusted to 30 dyn/cm.
A monolayer of cadmium araxinate was accumulated on the substrate while increasing the temperature to a certain temperature and holding it. The substrate speed was 10 mm/min both during dipping and pulling up, and the speed was set at 40 mm/min.
A dielectric layer 2 was obtained by accumulating layers of cadmium araxinate monolayer. Further, after the substrate was turned upside down with respect to the dipping direction, two bis-tetracyanoquinodimethane docosylpyridinium monomolecular films were accumulated to form a conductive layer 3 under the same conditions as in the case of forming the conductive layer 1.

Next, a lead-out electrode was provided at the end of the conductive layer 1.3 using a conductive paste as shown in FIG. 1, thereby producing an organic thin film capacitor of the present invention. The extraction electrode was connected to an external circuit and the capacitance was measured, and as a result, a value of 0.02 μF was obtained.

Example 2 A capacitor having the structure as shown in FIG. 2 was formed using an apparatus as shown in FIG. 3a, a three-layer diagram.

After forming the conductive layer 3 in Example 1, 40 layers of a cadmium araxinate monolayer were again accumulated, and after the substrate was turned upside down, two layers of a bis-tetracyanoquinodimethane docosylviridinium monolayer were accumulated. Thereafter, a laminated plate of electrode sheets g & 6 was produced using the same process. All film forming conditions are the same as in Example 1. Next, a lead-out electrode was provided in the same manner as in Example 1 to produce an organic thin film capacitor of the present invention. As a result of measuring the capacitance, a value approximately five times that of Example 1 was obtained.

Example 3 Organic thin film capacitors were created in which the cumulative number of layers of the cadmium alaxinate monolayer used as the dielectric layer in Example 1 was changed to 80, 60, 40, 30, 20, and 10 layers. did. All processes and film forming conditions are the same as Example 1.
is the same as A lead-out electrode was set up in the same manner as in Example 1, and the capacitance was measured. As a result, it was confirmed that there was an inversely proportional relationship between the cumulative number of dielectric layers and the capacitance. However, when the cumulative number of dielectric layers was 10, the dielectric breakdown voltage was several volts or less.

Example 4 Organic thin film capacitors were prepared in Example 1 except that the cumulative number of conductive layers 1 and 3 was 11 and 10, respectively. All the steps and film-forming conditions are the same as in Example 1. Further, the cumulative number of layers of the cadmium araxinate monomolecular film used as the dielectric layer was 40 layers. An extraction electrode was provided in the same manner as in Example 1, and electrical transient characteristics were measured. Since the conductivity of the conductive layer was higher than that produced in Example 1, the transient characteristics could be significantly improved.

〔Effect of the invention〕

The organic thin film capacitor of the present invention has a conductive layer and a dielectric layer made only of organic materials, can be easily produced even at room temperature and pressure, and has a g-film with extremely uniform inter-electrode spacing. An extremely uniform electric shock can be obtained between the electrodes, resulting in the effect that high designability can be obtained.

[Brief explanation of drawings]

4A to 4C are cross-sectional views schematically illustrating a method for producing a dielectric layer and a conductive layer of an organic thin film capacitor according to the present invention. 1: Conductive layer 2: Dielectric layer 3: Conductive layer 4: Take-out electrode 5: Take-out electrode 6: Glass substrate 7: Surface pressure needle 8 2 Surface pressure control device 9: Movement barrier 10: Water phase 11: Film forming substrate 12: Film forming holder 13: Surface pressure sensor 14: Water tank 15: Film forming molecule 16: Hydrophilic site 17: Hydrophobic site

Claims (1)

[Claims] A conductive layer containing a monolayer of an organic molecule having both a hydrophilic site and a hydrophobic site or a cumulative film thereof, and a monolayer of an organic molecule having both a hydrophilic site and a hydrophobic site or its An organic thin film capacitor comprising a stack of dielectric layers including cumulative films and two lead-out electrodes, wherein each of the conductive layers is alternately connected to a different lead-out electrode.