JPH04178434A - Production of organic thin film and production device therefor - Google Patents

Abstract

PURPOSE:To efficiently promote chemical reaction and to obtain a stable organic thin film in excellent controllability by vaporizing organic molecules in a vacuum chamber, monomolecularly piling the organic molecules on a substrate to form a thin film and then subjecting to combination of light irradiation and impression of high magnetic field. CONSTITUTION:At least one kind of organic molecules as a solid source is fed to cells 5, heated in a vacuum chamber 1 in a vacuum state, vaporized, passed as a molecular beam through shutters 6, the organic molecules having reached a substrate 2 are adsorbed on the substrate 2 to form an orientated monomolecular film. An operation of irradiation with a laser beam from a high-quality photon beam generator 7 to polymerize the organic molecules, to form a polymer and stabilize the molecules and an operation of photo- crosslinking in the monomolecular film by impression of high magnetic field by a high magnetic field generator 4 are simultaneously or successively carried out to give the objective organic thin film.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to optical thin films for use in high-strength protective films, lubricating films, mixed gas separation films, high conductivity conductive films, electronic devices, nonlinear optical effects, etc. The present invention relates to an apparatus and method for manufacturing organic thin films used in the formation of organic thin films.

[Prior Art] In recent years, the formation of high performance or highly functional organic thin films has attracted attention due to the wide range of fields of application.

In particular, it is not just a thin film made from a bulk material with a random structure as in the past, but an organic thin film in which organic molecules are highly oriented, aligned or crystallized, and is formed by combining different types of molecules. There is a need to produce organic thin films with improved performance or novel functions.

Conventionally, methods for producing organic thin films include solvent evaporation,
Spin code method, barcode method, LB (Langmui
Known methods include the r-Blodgett method, vacuum evaporation method, cluster ion beam method, and plasma CVD method.

[Problem to be solved by the invention] However, although the solvent, medium evaporation method, spin code method, barcode method, etc. are widely used because they are easy and simple, the resulting film is an amorphous non-isotropic film. For,
There is a problem in that it is difficult to form an organic thin film with controlled orientation.

On the other hand, the LB method, vacuum evaporation method, and cluster ion beam method are capable of forming organic thin films whose orientation can be controlled, but each has the following problems.

In other words, in the LB method, a monomolecular film developed on a water surface is transferred onto a substrate using a vertical dipping method or a horizontal deposition method, so there are restrictions on the molecular structure that can be produced, and the resulting thin film has many defects. There is also the issue of becoming. Furthermore, in a structure with two or more layers, there is a problem that the orientation becomes unstable over time, which causes many problems in application to devices and the like.

Next, the vacuum evaporation method and the cluster ion beam method have advantages such as less contamination of impurities because they are dry processes, and their orientation controllability can also be controlled to some extent by adjusting various film forming conditions. It is possible. The organic MBE method, which is performed under a higher vacuum than this vacuum evaporation method, slowly evaporates organic molecules into a molecular beam shape to create a thin film, which allows for controllability of the orientation of organic molecules. However, these methods rely on physical processes such as physical adsorption and crystal formation in the deposition of molecules onto a substrate, and do not require chemical reactions to occur simultaneously with the film formation process. Currently, there is no film-forming method.Furthermore, plasma polymerization CVD is a film-forming method that uses a chemical reaction process, but it is almost impossible to control the reaction, and molecules in the film Orientation control is also not possible.

This is a method of highly oriented, aligned or crystallized organic molecules, and then using chemical reaction processes between molecules to create highly stable, high-performance organic thin films or organic thin films with novel functions. The current situation is that there is no.

The present invention was made in view of the above-mentioned problems, and provides an apparatus and method for manufacturing an organic thin film in which the film structure is precisely controlled and an organic thin film having a novel function is formed. The purpose is to

[Means for Solving the Problems] The organic thin film manufacturing apparatus of the present invention includes a vacuum chamber, means for supporting a thin film forming substrate and organic molecules in the vacuum chamber facing each other, and a means for supporting the organic molecules in a gaseous manner. photon beam generating means for generating light of at least one wavelength and irradiating the gasified molecules; and high magnetic field generating means for generating a high magnetic field and applying it to the gaseous molecules. It is composed of:

Further, the second invention is such that organic molecules are gasified in a vacuum chamber and attached to the substrate, and then light of at least one wavelength is irradiated, or a high magnetic field is applied simultaneously or sequentially with light irradiation. This is what I did.

[Function] According to the present invention, a monomolecular film prepared by light irradiation can be polymerized to stabilize the polymer, and specific parts of organic molecules can be photoactivated to prevent chemical reactions with other molecules. Furthermore, by applying a high magnetic field, it is possible to act on the photoactivated radicals and control their intersystem crossing, thereby stabilizing the radicals and selecting the reaction route. I can make you do it.

[Example] Hereinafter, the present invention will be explained with reference to figures which are examples.

FIG. 1 is a schematic diagram showing an organic thin film manufacturing apparatus according to each embodiment of the present invention. In the figure, l indicates a vacuum chamber, which is evacuated through an exhaust port 1a and maintains the interior in a vacuum state. It is. The degree of vacuum is desirably high from the viewpoint of film formation, and in practical terms, a high vacuum of 10-87°rr or less is preferably used. 2 is a substrate for forming a thin film, 3 is a substrate holder that rotatably holds the substrate 2 in the vacuum temperer 1, and the second substrate holder 3 has a heating and/or cooling device for adjusting the substrate 2 to a predetermined temperature. It has a mechanism. Reference numeral 4 denotes a high magnetic field generator that is placed close to the substrate holder 3 and generates a high magnetic field. Further, reference numeral 5 indicates a plurality of Knudsens (K nu
dsen (hereinafter referred to as K) is a cell that is equipped with an organic material and then processed to emit a molecular beam of the organic material. 6 is the shutter provided in each cell 5.
Then, the amount of irradiation of the molecular beam onto the substrate 2 is controlled. In addition,
In addition to solids, gases and liquids can be used as organic materials, and a crucible used in the cluster ion beam method may be attached to some or all of these in the cell 5. In that case, although not shown in this figure, a device such as an electron generator for ionization may be installed.

Furthermore, 7 is a high-quality photon beam generator that generates light such as a laser beam and irradiates it onto the substrate 2, and 8 is a spectroscopic measurement device that detects the light reflected from the substrate 2 and analyzes the state of the thin film on the substrate 2. The means or energy detector 9.10 is a high-quality photon beam generator and a spectroscopic measurement means that detect changes in light caused by a molecular beam of an organic material and analyze the molecular beam, respectively, and these lights are transmitted to the side of the vacuum chamber 1. The light is sent and received through a light irradiation window 11 provided in the section. Further, a liquid nitrogen shroud 12 is provided to prevent the substrate 2 from being contaminated from the surrounding area.Furthermore, although not shown in the figure, a similar liquid nitrogen shroud is placed around the K cell 5. It is also possible to prevent contamination from

Furthermore, in addition to these devices, mass spectrometers [13, high-speed electron diffraction (RHE)
Although an electron gun 14 for ED), a screen 15 for RHEED, and a film thickness gauge 16 are provided, these do not need to be provided as part of the film forming apparatus.

FIG. 2 shows a first embodiment of forming an organic thin film using such an apparatus. The organic molecule 21 used has a linear structure and has polymerizable groups such as diacetylene bonds and unsaturated bonds, and has an electron-donating group, an electron-withdrawing group, a hydrophobic group, and a hydrophilic group at both ends. Substrate 2 such as a sexual group, etc.
It shall have a polar group that is likely to be selectively adsorbed to. Furthermore, for both end groups, a material that can undergo a radical reaction by photoexcitation is selected.

First, organic molecules are introduced into cell 5 as a solid source,
It is gasified by heating under vacuum conditions. By adjusting the conditions in step 2, the organic molecules reach the substrate 2 through the shibotter 6 in the form of a single molecule or a molecular beam on the order of molecules since the organic molecules are under an ultra-high vacuum. The organic molecules 21 that have arrived are selectively adsorbed onto the substrate 2 on the side having groups that have a strong adsorption force with the substrate 2, forming an oriented monomolecular film as shown in FIG. 2(a). This state of orientation is stable if the molecules form a single crystal, but otherwise it is maintained only by the cohesive force of the molecules and the adsorption force with the substrate 2, and becomes unstable over time. become. Therefore, next, high-quality photo generation-1 generation device ff7
The molecules are irradiated with laser light to polymerize the molecules, forming a polymer and stabilizing the molecules. (Figure 2(b)) Although the organic molecules that form single crystals are very limited, the range of material selection can be expanded by using this polymerization stabilization method. In addition, in order to selectively cause a polymerization reaction, it is desirable that the light be a high-quality photon 1 as shown in Figure 2 (b). Light with excellent controllability, such as a laser beam, is preferable.

A second monolayer film is formed on the oriented monomolecular film stabilized in this way. At this time, first, the exposed end of the first monomolecular layer is optically excited with high quality photons 2. (Figure 2 (C)) This photoactivated radical state is irradiated with the next molecular beam to cause a chemical reaction, resulting in a stable second radical.
forms a monolayer of (FIG. 2(d)) The lifetime of photoexcited radicals is generally short and reduces the efficiency of chemical reactions, so application of a high magnetic field is often effective in extending the lifetime of radicals. The deactivation of radicals is usually due to sleep crossover, and the mechanisms governing the sleep crossover are mainly Zeeman interactions, hyperfine interactions, and spin relaxation interactions. Which mechanism is dominant depends on the individual molecule.

Furthermore, the effect that the efficiency of chemical reactions is improved by the application of a magnetic field is known as the cage effect, and for this to occur, it is necessary that the cross-over of molecules is dominated by hyperfine interactions or spin-relaxation interactions. is necessary. In the present invention, this principle is applied to efficiently promote the chemical reaction with the second monolayer. At this time, if the timing of the application of a high magnetic field, the irradiation of high-quality photons 2, and the irradiation of molecular beams is adjusted in a pulsed manner, the reaction efficiency can be improved and unnecessary reactions can be prevented. There are advantages. Furthermore, it is also possible to use a reaction path control mechanism using multi-stage particle excitation using the third high-quality photon whose timing is adjusted, and it is possible to improve the controllability of the reaction.

Next, after the second monomolecular layer is formed, the second monomolecular layer is polymerized by irradiation with high quality photons l, and is stabilized by polymerization. Thereafter, a multilayer film is obtained by repeating irradiation with high-quality photons 2, application of a high magnetic field, formation of a third monomolecular layer, and irradiation with high-quality photons 1.

By configuring as in 2, a structure in which organic molecules are oriented in one direction along the film thickness direction can be obtained.

By forming a monomolecular film using two or more types of molecules in a preset order, an organic thin film with a superlattice structure can be easily obtained. In addition, because the present invention is characterized by a dry process in an ultra-high vacuum, it is possible to obtain a film with fewer impurities (and fewer defects), and because the structure is stabilized, it is stable over time. An oriented molecular thin film with excellent mechanical strength and mechanical strength can be obtained.

FIG. 3 shows a second implementation method of the invention.

In this embodiment, first, a molecular beam of organic molecules 22 is formed in the same manner as in the first embodiment, and an oriented monomolecular film is formed on the substrate 2. Thereafter, by adjusting conditions such as the molecular beam and the temperature of the substrate 2, second and third monomolecular films are epitaxially grown as shown in FIG. 3(a). Such an oriented molecular multilayer film is unstable over time unless it is in a perfect single crystal state.

However, as described above, the range of material selection is limited in order to form a single crystal. Therefore, as shown in FIG. 3(b), the oriented molecular multilayer film can be stabilized by irradiating high quality photons 2 and applying a high magnetic field to cause optical crosslinks between each single molecule.

As described above, in this example, the structure of the organic thin film to be produced can be controlled depending on whether or not a magnetic field is applied, and a thin film with a desired stable structure can be formed.

FIG. 4 shows a third implementation method of the present invention, and the organic molecule 23 used in this example is one having a diacetylene bond among the organic molecules used in the first example.

First, as in the first embodiment, the organic molecules 23 are gasified to form a molecular beam, and the substrate 2 is irradiated with the molecular beam to form a monomolecular film as shown in FIG. 4(a). The diacetylene bonds of the formed oriented monomolecular film are polymerized by light irradiation, thereby becoming polymerized and stabilized. The normal polymerization reaction of diacetylene is shown in Figure 4(c).
, 4 addition reaction. In contrast, according to the present invention, by applying a high magnetic field, it is possible to control the formation position of radicals within the molecule and control the reaction path. Specifically, by applying a high magnetic field, the
1 as shown in 1. A 2-addition reaction or a 3.4-addition reaction can be caused.

Also, 1. In the case of 2-addition reaction or 3,4-addition reaction,
Further, by irradiation with high-quality photons 2, which is another type of light, a boria heptane structure can be formed.

As shown in item 2, in this example, organic thin films with various structures can be formed by selecting reaction paths depending on whether or not a high magnetic field is applied. Furthermore, the obtained polydiacetylene is a π-conjugated polymer, and is expected to have functions such as electronic conductivity and nonlinear optical properties.

FIG. 5 shows the fourth method of implementing the present invention, in which the organic molecule 24 used in this example has a polymerizable group, a donor functional group at both ends, and an ac7buteric functional group. Retains functional groups. The figure shows an example in which a diacetylene group is used as the polymerizable group, but other polymerizable groups, such as
Vinyl groups, acetylene groups, etc. can also be used. As the donor functional group, in addition to normal donor groups, groups that emit electrons when irradiated with light are used. Specifically,
Compounds having a triphenyl group, aliphatic compounds represented by substituted amines such as diprolamine, dipropylamine, diisopropylamine, anthramine, benzanthramine, substituted benzanthrani, dibenzanthramine, dibenzanthramine N, Hisenpyrene, Benzopyrene,
Carbocyclic aromatic compounds such as dibenzoolene, phenyl diamine, heterocyclic compounds such as hyalocholine, thiophene, substituted thiophene, furan, substituted furan, pyrrole, substituted virole, and even tetrathiafuronylenotoso. Examples include functional groups that form charge-transfer complexes such as derivatives.In addition to normal ac-7-buter groups, examples include groups that accept electrons when irradiated with light. Acrylic acid, aliphatic compounds such as a7damide, ethylene oxide, carbon carbocyclic aromatic compounds such as nitrobenzene, benzoquinone, tetraano-p-benzoquinone derivatives, tetranoanoquinosimethane, tetracyanoethylene, etc. Examples include functional groups that form derivatives thereof.

First, in the first step, as in the first embodiment, a molecular beam is formed by gasifying in a vacuum, and the substrate 2 is irradiated with the molecular beam to form a monomolecular film. (FIG. 5(a)) Next, this monomolecular film is irradiated with high-quality photons 3 to cause a charge transfer reaction and generate anion radicals 25 and cation radicals 26.

(FIG. 5(b)) At this time, the generated radical pairs are deactivated with a lifetime depending on the molecular structure and environment, but by applying a high magnetic field, it is possible to extend the lifetime. That is, as shown in FIG. 5 <C), by irradiating with high quality photons 4, the diacetylene bond portion is polymerized while keeping the radical pair active. In addition, in order to form radicals, it is preferable to use a combination in which the material is neutral, with no charge transfer occurring in the ground state, and in which charge transfer occurs upon irradiation with light, since such materials have unpaired electrons. It can also be used as a magnetic material.

In addition, in the above-mentioned example, the case where one kind of light is irradiated was explained, but in the fourth example, there are two reaction sites, and each of them is selectively reacted by irradiation with light of a different wavelength. It may also be configured to
Even if two or more kinds of molecules are used in combination or in a mixture, a thin film can be formed in the same manner without any problem in the process.

Further, the source is not limited to solid, but gas and liquid can also be used. Furthermore, the high-quality first beam used in the present invention may be any light beam that has excellent monochromaticity, directivity, time controllability, etc., such as a laser beam, and its wavelength depends on the material used. In most cases, the ultraviolet to visible range is preferred, although it also depends on the wavelength.

Specific lasers include an echimmer laser, an Ar ion laser, a Kr ion laser, and a HeNe laser. Furthermore, when high-quality photons are used as a heat source, such as when forming a pyropolymer, an infrared laser such as a carbon dioxide laser, a YAG laser, or a YLF laser may also be used. . Furthermore, examples of materials used for film formation in the present invention include diacetylene materials, and examples of such materials are shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, a highly oriented organic thin film can be obtained by controlling it on the molecular order, and moreover, by combining light irradiation and application of a high magnetic field, chemical It becomes possible to efficiently promote the reaction and select the reaction route, which has the effect of producing stable organic thin films with good controllability.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a film forming apparatus which is an embodiment of the present invention, Fig. 2 is a reaction diagram showing a first implementation method of the invention, and Fig. 3 is a diagram showing a second implementation method of the invention. Reaction diagram shown, 4th
The figure is a reaction diagram showing the third implementation method of the present invention, Figure 5 is a reaction diagram showing the fourth implementation method of the invention, and Figure 6 is a structural example of a diacetylene compound that can be used in each example. FIG. In the figure, l is a vacuum chamber, 2 is a substrate, 3 is a substrate holder, 4 is a high magnetic field generator, 5 is a cell, 6 is a shutter, 7 is a high-quality photon beam generator, 8 is a spectroscopic measurement system or energy detection 9 is a high-quality photon beam generator, 10 is a spectroscopic measurement system or energy detector, 11 is a light irradiation window, 12 is a liquid nitrogen cloud, 13 is a mass spectrometer, and 14 is an electron gun for high-speed electron beam diffraction. , 15 is the RHEED screen, IB is the film thickness meter, 21
．． 22. 23°24 are organic molecules.

Claims (3)

[Claims] (1) a vacuum chamber, a means for supporting a thin film forming substrate in the vacuum chamber, a means for gasifying the organic molecule and adhering it to the substrate, and generating light of at least one wavelength to convert the organic molecule into a gas. An apparatus for manufacturing an organic thin film, comprising: a photon beam generating means for irradiating molecules; and a high magnetic field generating means for generating a high magnetic field and applying it to the gasified molecules. (2) In a method of forming a thin film by gasifying at least one kind of organic molecule in a vacuum chamber and depositing it on a substrate, the step of irradiating light with at least one wavelength and the step of applying a high magnetic field are performed simultaneously or A method for manufacturing an organic thin film, characterized in that the steps are performed in sequence. (3) The method for producing an organic thin film according to claim 2, characterized in that a photopolymerizable monomer containing at least one of an electron-donating group and an electron-accepting group in its molecule is used. Method.