JPS6370543A - Processing for organic conductive layer - Google Patents

Abstract

PURPOSE:To obtain a processing method, by which a highly accurate and fine pattern can be easily formed without damaging the characteristics of an organic conductive layer, by a method wherein impurities which make conductivity lower or dissipate are implanted or diffused in desired places of the conductive layer of an electrical element having the organic conductive layer. CONSTITUTION:Impurities 9 which make a conductivity lower or dissipate are implanted or diffused in an organic conductive layer on a substrate 2, that is, desired regions 8 of the accumulated film 5 of monomolecular films consisting of an organic chargetransfer complex, through a desired pattern mask 10 and the low or non-conductive regions 8 are formed. As the impurities to be used, non-conductive materials having a good diffusivity are desirable, such as hydrogen, helium, nitrogen, oxygen, fluorine, neon and argon are useful. According to this method, as there is no need to destruct whatever the organic conductive layer on the substrate in the formation of a pattern, the pattern can be easily formed at an arbitrary region without exerting bad effect whatever except the region to be formed with the pattern. As a result, a highprecision and fine processing is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for processing an electric device, and more specifically, to easily fabricate a low conductivity or non-conductivity region in a desired portion of an electric device having an organic conductive layer. The present invention relates to a method of patterning a conductive layer by forming a conductive layer.

(Prior Art) Conventionally, various electric elements such as ICs and semiconductors are known, and in most cases, inorganic substances are used as materials for the functional parts of these electric elements.

However, as these electrical devices are increasingly required to have a higher degree of 1 degree, higher miniaturization, and higher integration, the use of conductive organic materials that are easy to handle and have a wide variety of types as materials for functional parts of semiconductor devices is being widely considered. I'm nestling.

Organic charge transfer complexes are known as a type of conductive organic material, and a method for forming such organic charge transfer complexes as a uniform film on any substrate is the Langmuir-Prodget method proposed by Langmuir et al. Method (LB method)
It has been known.

According to this LB method, a monomolecular film or a cumulative film thereof of an organic charge transfer complex in which a hydrophobic site and a hydrophilic site are 'IT'ed in one molecule can be easily formed on a substrate. The organic conductive layer formed in this way has good electrical conductivity in the horizontal direction of the film because the hydrophobic regions with high electrical insulation and the hydrophilic regions with high conductivity overlap in a planar manner. It has the unique property of conductive anisotropy, which shows high insulating properties in the direction perpendicular to the film.

(Problems to be Solved by the Invention) The organic conductive layer as described above has extremely uniform conductivity in the plane direction of the layer, and is expected to have various uses. When used as various electric elements, such as electric circuits,
It is necessary to microfabricate these conductive layers into arbitrary-shaped patterns. As such a microfabrication method, for example, a method of forming and growing a conductive layer as described above in a pattern on a substrate has been considered.
ByA is formed by a method in which a uniform monomolecular film developed on an aqueous phase is transferred onto a substrate, so the formation of such a patterned film has not yet reached a practical level.

Another method is to pattern the LB film once formed by post-processing, for example, an etching method that removes a desired region of the film, but this method differs from chemical etching of inorganic materials and uses a mask. There is a problem in that it is difficult to select materials, masking methods, etching agents, etc., and there is a great possibility that the conductive layer other than the etched area will be altered by the etching agent. In particular, electric elements are densely packed.
The higher the degree of integration, the more difficult such microfabrication becomes, which poses a problem in that it is not possible to take advantage of the excellent properties of a layer consisting of a monomolecular film or a cumulative film of an organic charge transfer complex.

Therefore, there is a need for a processing method that can easily form fine patterns with high grain size on electrical elements having functional parts made of conductive organic materials as described above, without impairing the characteristics of these layers.

(Means for Solving the Problems) In order to meet the demands of the prior art as described above, the present inventors have conducted extensive research without impairing the precision of the conductive layer or its characteristics, which may also be a conductive organic material. We have discovered a method that allows easy microfabrication.

That is, the present invention is a method for processing an organic conductive layer, which is characterized by implanting or diffusing an impurity that reduces or eliminates conductivity into a desired location of a conductive layer of an electric element having an organic conductive layer.

Next, the present invention will be explained in more detail.

The electrical device to be microfabricated in the present invention is generally an electrical device having a tE-conducting organic layer on an arbitrary substrate.
It is an electric element obtained by forming a single molecule of an organic charge transfer complex or a cumulative film thereof on an arbitrary substrate.

The charge transfer complex used to form the organic conductive layer in the present invention is a compound having a hydrophilic site, a hydrophobic site, and a conductive site within one molecule.

Any of the conventionally known charge transfer complexes having such conditions can be used in the present invention, but a compound suitable for the present invention has a hydrophilic moiety having a quaternary ammonium group and a hydrophobic moiety having an alkyl group or an aryl group. It is a charge transfer complex in which the electroconductive part is a hydrophobic hydrocarbon group such as a group or an alkylaryl group, and the conductive part is a tetracyanoquinodimethane structure.

A preferable compound as the charge transfer complex is the following general formula (
I).

[A] [TCNQ]n Xm (I) Examples include the following compounds.

R in the above is a hydrophobic moiety, and is an alkyl group, an aryl group, or an alkylaryl group, and preferably an alkyl group having 5 to 30 carbon atoms. R1 is a lower alkyl group, n and q are 0, 1 or 2, m is 0 or 1, and X is an anion group such as a halogen ion such as a bromine ion or a perchlorate ion. Y is oxygen or sulfur.

The above compounds may further have a polymerizable group such as a double bond or triple bond in the alkyl group, and may have a polymerizable group such as a double bond or triple bond on the heterocycle.
It may have one or more substituents such as an alkyl group, an alkenyl group, a cyano group, an alkoxy group, or a halogen.

Moreover, TCNQ is a compound represented by the following formula.

The a to d positions in the above formula may have arbitrary substituents such as an alkyl group, an alkenyl group, and a halogen atom.

The present inventor has conducted intensive research on charge transfer complexes including the compounds exemplified above, and has found that these charge transfer complexes can be formed as a monomolecular film or a composite thereof on any substrate by a known method. In addition, such a monomolecular film or a cumulative film thereof has high insulating properties in the vertical direction of the film and high conductivity in the horizontal direction of the film. It was discovered that the material exhibits excellent anisotropy of conductivity.

In the present invention, a preferred method for forming a conductive layer on the surface of any substrate using the charge transfer complex is the LB method described above.

In the LB method, for example, in a molecule having a structure having a hydrophilic site and a hydrophobic site in the molecule, such as the above-mentioned charge transfer complex, when the balance between the two (balance of amphiphilicity) is maintained appropriately, This is a method to create a monomolecular film or a cumulative film thereof by utilizing the fact that molecules form a monomolecular layer on the water surface with their hydrophilic groups facing downward.

A monomolecular layer on the water surface has the characteristics of a two-dimensional system, and when the molecules are sparsely dispersed, the two-dimensional ideal gas equation, πA=, is expressed between the surface &7A per molecule and the surface pressure π. T holds true and becomes a “gas film”. Here, K is Boltzmann's constant and T is absolute temperature. If A is made sufficiently small, the intermolecular interaction becomes stronger, resulting in a -dimensional solid "condensed film (or solid film)". The condensed film can be transferred layer by layer onto the surface of arbitrary objects having various materials and shapes, such as glass and resin. Using this method, a monolayer or a cumulative film thereof can be formed from the charge transfer complex and used as a conductive layer for an electrical device.

As a specific manufacturing method, for example, the method shown below can be mentioned.

The desired charge transfer complex is dissolved in a solvent such as chloroform, benzene, acetonitrile, etc. Next, using a suitable apparatus as shown in FIG. 1 of the accompanying drawings, the charge transfer complex is spread on the aqueous phase 1, which is a solution of the charge transfer complex, to form a charge transfer complex in the form of a film.

Next, a partition plate (or float) 3 is provided to prevent this spread layer from spreading freely on the water phase and spreading too much, and by limiting the spread area, the state of aggregation of the membrane material is controlled, and it is proportional to the state of aggregation. Obtain the surface pressure π. By moving the partition plate 3, the developed area can be reduced to control the aggregation state of the membrane material, and the surface pressure can be gradually increased to set the surface pressure π suitable for membrane production. While maintaining this surface pressure, the monomolecular film of the charge transfer complex is transferred onto the substrate 2 by gently raising or lowering the clean substrate 2 vertically. Such a monomolecular film is a film in which molecules are arranged in an orderly manner as schematically shown in FIG. 2a or 2b.

A monomolecular film of the charge transfer complex is manufactured as described above, and by repeating the above operations, a cumulative film having a desired cumulative number h1 is formed. To transfer the monomolecular film of the charge transfer complex onto the substrate, other than the above-mentioned vertical dipping method, methods such as horizontal deposition method and rotating cylinder method can also be used.

The horizontal deposition method is a method in which a monomolecular film is transferred by bringing the substrate into horizontal contact with the water surface, and the rotating cylinder method is a method in which a cylindrical substrate is rotated above the water surface to transfer the monomolecular film onto the substrate surface. be.

In the vertical immersion method described above, when a substrate with a hydrophilic surface is lifted out of water in a direction across the water surface, a monomolecular film of the charge transfer complex is formed on the substrate with the hydrophilic groups of the charge transfer complex facing the substrate. (Figure 2b). When the substrate is moved up and down as described above, a stacked M film is formed by stacking one monomolecular film at each step. Since the direction of the film-forming molecules is reversed during the pulling process and the dipping process, according to this method, between each layer of the monolayer, the hydrophobic groups of the charge transfer complex face each other.
A mold film is formed (FIG. 3a). In contrast, in the horizontal deposition method, a monomolecular film with the hydrophobic groups of the charge transfer complex facing the substrate is formed on the substrate (FIG. 2a). in this way,
Even when monomolecular films are accumulated, there is no change in the direction of the film-forming molecules, and an X-shaped film is formed in which the hydrophobic groups face the substrate in all layers (FIG. 3b). On the other hand, a cumulative film in which the hydrophilic groups in all layers face the substrate side is called a Z-type film (Figure 3c).

The method of transferring the monomolecular film onto the substrate is not limited to the above method, and when using a large-area substrate, a method of extruding the substrate from a roll into an aqueous phase may also be adopted. Further, the directions of the hydrophilic groups and hydrophobic groups described above toward the substrate are in principle, and can be changed by surface treatment of the substrate, etc.

As described above, a conductive layer consisting of a monomolecular film of the charge transfer complex or a cumulative film thereof is formed on the substrate.

In the present invention, the substrate for forming an organic conductive layer consisting of a monomolecular film of a charge transfer complex or a cumulative film thereof as described above may be made of any material such as metal, glass, ceramics, or plastic material. Significantly lower biomaterials can also be used.

As mentioned above, conductive materials such as metals can also be used.
This is because the monomolecular film or the cumulative film has sufficient insulating properties in the direction perpendicular to the film.

The above-mentioned substrate may have any shape, preferably a flat plate, but is not limited to a flat plate at all. That is, the present invention has the advantage that a film can be formed in accordance with any shape of the surface of the substrate.

A preferred method for microfabrication of the organic conductive layer formed on the substrate as described above is as shown in FIG. This is a method of forming a low or non-conductive region 8 by implanting or diffusing an impurity 9 into the desired region 8 through a desired pattern mask 10 to reduce or eliminate the conductivity. The impurity used is preferably a non-conductive material with good diffusivity, such as hydrogen, helium, nitrogen,
Oxygen, fluorine, neon, argon and the like are useful, with argon, neon, oxygen and fluorine being particularly preferred. Although there are various methods for injecting or diffusing these impurities into the organic conductive layer, an ion implantation method is a suitable method.

The ion implantation method involves ionizing the target element in a vacuum, electrostatically accelerating the ions to the required energy, and then implanting them into the target (target object). It also has the characteristics of being able to implant impurities that cannot be implanted, and being suitable for microfabrication.

Furthermore, this method is well established as a semiconductor manufacturing technology, and has high reliability, easy handling of the device, and high productivity. Furthermore, the process itself can be carried out at room temperature, and can be said to be one of the methods extremely suitable for organic materials.

As the implanted ions, for example, all of the impurity examples mentioned above can be used, and among them, inert gas such as argon is easy to handle and has a large effect. On the other hand, active species such as oxygen and fluorine are also highly advantageous because they directly react with membrane constituent molecules, greatly reducing conductivity and causing a drop.

The methods described above are typical methods, and any method that provides the same effects as those described above can be used in the present invention.

In addition, in the present invention, when the charge transfer complex used has a polymerizable group, after forming the film as described above, and before or after microfabrication, these films are polymerized and hardened to increase the film strength. It can also be significantly improved.

(Operations/Effects) According to the present invention as described above, since a heating process at a particularly high temperature is not required for microfabrication of an organic conductive layer, the substrate used is not limited to organic materials, inorganic materials, living organisms, etc. Any substrate can be used.

Further, according to the method of the present invention, when forming a pattern,
Since there is no need to destroy the organic conductive layer on the substrate, patterns can be easily formed in any area without any adverse effects on areas other than the area where the pattern is to be formed, allowing for highly fine processing. Therefore, it has become possible to easily provide electric elements with excellent electrical characteristics with good reproducibility.

From the above points, according to the present invention, the electric device produced by the method of the present invention can be highly expected not only as a conventional high-density electric device but also as a bioelectronic device that utilizes living organisms.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 The above charge transfer complex was added to a mixed solvent of benzene-acetonitrile (volume ratio 1:1) at 1 mg/mJ! After dissolving at a concentration of Cd, the pH was adjusted to 6,8 with H(:Os).
Cl2 vA degree 4X10-'mol/ffi, water Qt
Developed on aqueous phase at 7°C.

After removing the solvents acetonitrile and benzene by evaporation,
The surface pressure was increased to 20 dyne/cm to form a monomolecular film. While keeping the surface pressure constant, an intrinsic (i-type) silicon wafer cut out in advance into a 1010x30 rectangle was used as a substrate, and the speed was 15a+m1 in the direction across the water surface.
After gently immersing the board at 0+in for about 201111 minutes,
Next, gently pull up at speed 10wIII/win 2
A monolayer of layers was accumulated. The above cumulative operation was repeated again to form a monomolecular film "A" on the substrate.

Furthermore, a pair of external connection electrodes 1 in a stripe shape as shown in FIG.
1 was formed. At this time, the width of the electrode is 20101, the length is 10
1! lfl! , the electrode spacing was 2Il111. Next, this situation! Measure the current-voltage characteristics of the element with breath and calculate the sheet resistance ρ
When S was determined, it was 240Ω/mouth. Further, using a mask 10 made of nickel permalloy, argon 9 was ion-implanted at a concentration of 1X10''/cm' into a desired region 8 of the film. At this time, the acceleration voltage was set to 150 KeV, and the substrate temperature ffl was set to room temperature.

Incidentally, since the interval between the slits 12 of the mask 10 was 5 mm, the area of the region 8 into which argon ions were implanted was % of the total area sandwiched between the electrodes.

Furthermore, when ρS was determined by measuring the current-voltage characteristics once again, it was found to be 490Ω/mouth. This is approximately 2 of the value found earlier.
This shows that the conductivity of the desired region (here, the location of the conductive path between the electrodes) could be eliminated by ion implantation.

Example 2 A monomolecular cumulative film of bis-tetracyanoquinodimethandocylviridinium was prepared on a substrate in exactly the same manner as in Example 1, and a striped electrode was formed thereon. At this time, ρS was 240Ω/mouth based on the current-voltage characteristics.

Next, a 5iNtl film was formed to a thickness of 10 nm by a glow discharge method so as to cover the conductive path between the electrodes. Furthermore, this film was irradiated from above with argon ions at an acceleration voltage of 200 KeV in an amount of 5 x 1016/crn'' at room temperature.The irradiation area was % of the conductive path area between the electrodes, and the same mask as in Example 1 was used. The ρ of the sample obtained as above was used.
When I calculated S again, I found it to be 460Ω/mouth.

On the other hand, analysis of the sample by secondary ion mass spectrometry shows that ion beam mixing occurs in the argon ion irradiation region, and the constituent atoms of 5iNH1pQ (Si, N, tl)
was found to be diffused into the monomolecular cumulative film. ρS
The increase is due to the diffusion of these impurities, and it can be said that the degree of increase (approximately twice) is inversely proportional to the ratio of the ion irradiation area.

Example 3 A four-layer cumulative film of bis-tetracyanoquinodimethandocylviridinium was formed on a 20×30 nm i-type silicon wafer by the method described in Example 1. Furthermore, leaving a rectangular area (5 layers 5m+s) near the center of the sample, argon ions were added to the other area at an accelerating voltage of 150 eV.
The injection was performed at a dose of 016/crn'.

Further, as shown in FIG. 5, two electrodes 13 and 1 having a diameter of 2 to 3 m+aφ are formed at the corners of the rectangular unimplanted region 13 using a known method using silver paste.
Apply DC voltage V between 4, and at this time, the remaining 2 electric currents 8i1
Find the current I flowing between 5 and 16, and from this value va
A value of Ω/mouth was obtained for n der Pauw230.

As described above, the method of determining ρS and the Hall constant by the Yll der Pau method is very simple and is often used in inorganic semiconductors such as silicon.

In this example, impurity implantation is applied as a method for processing the shape of a measurement sample, thereby easily realizing the measurement method using an organic thin film.

Examples 4 to 8 As shown in Table 1 below, a monomolecular film was accumulated on a substrate in the same manner as in Example 1 regarding several types of charge transfer complexes, and the film was formed before and after ion implantation of impurities. The sheet resistance was measured. The results are also shown in Table 1 below (indicating the ratio of sheet resistance after implantation). Further, since the substrate and implanted impurity species were different from those in Example 1, they are also shown in Table 1. The acceleration voltage during ion implantation is 100
eV, and the implantation dose was 10"/crn" in both cases.
And so.

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[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a method of forming a conductive layer of an electric element of the present invention. FIG. 2 is a schematic diagram of a monomolecular film, and FIG. 3 is a schematic diagram of a cumulative film. 4 and 5 schematically show the method of processing an electric element of the present invention. 1; Water phase 2; Substrate 3: Float 4; Fit molecular film 5: Cumulative film 6; Hydrophilic site (conductive site) 7: Hydrophobic site 8: Injection region 9; Impurity 10: Mask 11: Electrode 12 Nislit 13 ~16; Electrode applicant: Canon Co., Ltd. Figure 1 Figure 2 & Figure 2b Figure Ja Figure 3b Figure 4 Figure 5 Figure 1

Claims (6)

[Claims] (1) A method for processing an organic conductive layer, which comprises injecting or diffusing an impurity that reduces or eliminates conductivity into a desired location of a conductive layer of an electric element having an organic conductive layer. (2) The method for processing an organic conductive layer according to claim (1), wherein the organic conductive layer is an anisotropic conductive layer. (3) The organic conductive layer according to claim (1), wherein the organic conductive layer is a monomolecular film of an organic charge transfer complex having a hydrophobic site, a hydrophilic site, and a conductive site in one molecule or a cumulative film thereof. Processing method of organic conductive layer. (4) The method for processing an organic conductive layer according to claim (1), wherein the organic charge transfer complex is a complex of a quaternary ammonium compound and tetracyanoquinodimethane. (5) The method for processing an organic conductive layer according to claim (1), wherein the impurity is argon, neon, oxygen, or fluorine. (6) The method for processing an organic conductive layer according to claim (1), wherein the impurity implantation or diffusion method is an ion implantation method.