JP2855330B2 - Organic film fabrication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method for producing an organic film that can be used for producing various organic films such as an organic nonlinear optical film and the like. With the aim of obtaining a good quality organic film with less dry process, organic molecules having electron donating and electron accepting groups are gasified in a vacuum chamber and alternately reach the substrate, Monolayers composed of the organic molecules are alternately deposited on the substrate by the adsorptive force between adjacent electron donating and electron accepting groups.

[Industrial applications]

The present invention relates to a method for producing an organic film that can be used for producing various organic films such as an organic nonlinear optical film.

[Conventional technology]

Conventionally, methods for producing an organic film include a solvent evaporation method,
Melt solidification method, spin coating method, LB method (Langmuir-Blodge
tt's technique), a vapor deposition method, and the like.

[Problems to be solved by the invention]

Among the above-described conventional methods for producing an organic film, the solvent evaporation method, the melt solidification method, and the pin coating method are simple,
Introductory film design such as superlattice structure and molecular orientation control cannot be performed.

In addition, although the LB method can be used for artificial film design, it is a wet method, and the organic film produced by this method has many defects. Therefore, it is not possible to manufacture a device using such an organic film. Have difficulty.

Furthermore, the vapor deposition method has a greater degree of freedom in film design than the solvent evaporation method, the melt solidification method, and the spin coating method described above, but requires a precise control required for controlling the superlattice structure and molecular orientation. I can't do that.

In view of the above problems, an object of the present invention is to make it possible to control a film structure extremely precisely and to obtain a high-quality organic film with few defects by a dry process.

[Means for solving the problem]

First, a first organic molecule having two or more electron-donating groups and a second organic molecule having two or more electron-accepting groups are gasified in a vacuum chamber to reach the substrate alternately. Then, the monomolecular layer composed of the first organic molecule and the monomolecular layer composed of the second organic molecule are alternately formed on the substrate by the adsorption force between the electron donating and electron accepting groups adjacent to each other. To be deposited.

Alternatively, first, an organic molecule having at least one of both an electron donating group and an electron accepting group is gasified in a vacuum chamber to reach the substrate. Then, monolayers composed of the organic molecules having the aligned molecular orientations are sequentially bonded and deposited on the substrate by the above-described adsorption force.

Alternatively, first, a first organic molecule having two or more first reactive groups and a second organic molecule having two or more second reactive groups are gasified in a vacuum chamber, and the substrates are alternately formed. To reach. Then, a monomolecular layer composed of the first organic molecule and the second organic molecule are formed on the substrate by a chemical reaction between the first reactive group and the second reactive group adjacent to each other. Monolayers are alternately bonded and deposited.

Alternatively, first, an organic molecule having at least one of both the first reactive group and the second reactive group is gasified in a vacuum chamber to reach the substrate. Then, by the above-described chemical reaction, monolayers of the organic molecules having the aligned molecular orientations are sequentially bonded and deposited on the substrate.

[Action]

An adsorption force based on Coulomb force is generated between the electron donating group and the electron accepting group. Then, by this adsorption power,
An organic molecule having an electron donating group and an organic molecule having an electron accepting group adsorb to each other (in the case of an organic molecule having both types of groups, the same type of molecules adsorb to each other).

Therefore, for example, when an electron-accepting substance is used as a substrate, when an organic molecule having an electron-donating group is gasified and reaches the substrate, the organic molecule is deposited on the substrate by the above-described adsorption force, and electrons are deposited on the substrate. A monolayer of organic molecules having a donor group is formed. Subsequently, when the organic molecule having an electron accepting group is gasified and reaches the substrate, the above layer receives the adsorbing force, and a monomolecular layer composed of the organic molecule having the electron accepting group is formed thereon. Is done. In this way,
For example, if multiple types of organic molecules each having an electron donating group and an electron accepting group are selectively and alternately deposited,
An organic film having a so-called superlattice structure can be easily obtained.

Further, for example, by sequentially depositing monomolecular layers made of the same kind of organic molecules having both an electron donating group and an electron accepting group, an organic film having strong molecular orientation can be easily obtained.

A similar effect can be obtained by using a chemical reaction between reactive groups instead of using the adsorbing force between the electron-accepting group and the electron-donating group.

Further, since the present invention is a dry process in a vacuum, a high quality film with less defects can be obtained as compared with the LB method.

Further, by polymerizing the organic film deposited on the substrate, an organic film having excellent mechanical strength can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a film forming apparatus used in each embodiment of the present invention to be described later. This apparatus is a conventional organic MBE.
(Molecular Beam Epitaxy) device.

In FIG. 1, an apparatus main body 1 includes a vacuum chamber 2 in which a high vacuum can be obtained by a vacuum pump, and a substrate holder 4 capable of fixing and supporting a film forming substrate 3 is provided on one side inside.
Is provided. The temperature of the substrate holder 4 can be controlled by a heater 4a and a cooler 4b, so that the substrate 3 can be set at a desired temperature. The above cooler
4b is cooled by flowing water, liquid nitrogen or liquid helium therein.

In the vacuum chamber 2, the substrate holder 4
A plurality (three in FIG. 2) of K (knudse
n) Cells 5, 6, and 7 are provided, and shutters are respectively provided at positions close to holes 5a, 6a, and 7a formed in these upper walls.
8,9,10 are arranged. Of the three K cells 5 to 7, two K cells 5, 6 are for containing solid sources 11, 12 made of different organic molecules according to each embodiment,
The remaining K cell 7 is for introducing the gas source 13 from an external gas cylinder or ampule (not shown) instead of using the two K cells 5 and 6 described above. The solid sources 11 and 12 are gasified by heating the K cells 5 and 6, respectively, and are ejected as gas molecules through the holes 5a and 6a. The gas source 13 in the K cell 7 is jetted as it is via the hole 7a as gas molecules. The ejection amount of each gas molecule from the K cells 5, 6, and 7 can be adjusted by controlling the opening and closing of each of the shutters 8, 9, and 10.

Further, a light irradiation window 14 for irradiating the substrate 3 with light such as ultraviolet light is provided on a side portion of the vacuum chamber 2.

Next, a first embodiment of the present invention will be described with reference to FIG. Here, a method for manufacturing a polydiacetylene film using diacetylene molecules (general structural formula RC = CC = CR ′) will be described as an example.

First, the electron donating group Diacetylene molecule having two (hereinafter referred to as molecule A)
And an electron-accepting group Diacetylene molecules (hereinafter, referred to as molecule B) having two of the following two solid sources 11 and 12 in FIG.
Into the K cells 5, 6. And vacuum chamber 2
The solid sources 11 and 12 are gasified in the K cells 5 and 6 while keeping the inside at a high vacuum.

Subsequently, a substrate made of an electron-accepting substance such as glass (SiO ₂ ) is used as the substrate 3. First, the shutter 8 on the K cell 5 is opened to allow the gasified molecules A to reach the substrate 3. Then, an adsorbing force acts between the molecule-donating group of the molecule A and the electron-accepting substrate 3, and as shown in FIG. The substrates are deposited while being arranged toward the substrate 3 side. At this time, the heater
By appropriately adjusting the temperature of the substrate 4 and the cooler 4b, the temperature of the substrate 3 is set to a temperature at which adsorption between the substrate 3 and the molecules A occurs but adsorption between the molecules A does not easily occur. At such a temperature, deposition of the molecule A hardly occurs after the molecule A is completely adsorbed on the substrate 3, so that a monomolecular layer 21 of the molecule A is formed on the substrate 3. When the formation of the monomolecular layer 21 is completed, the shutter 8 is closed, and the molecules A remaining in the vacuum chamber 2 are exhausted by a vacuum pump.

Thereafter, the shutter 9 on the K cell 6 is opened to allow the gasified molecules B to reach the substrate 3. Then, an adsorbing force acts between the electron-donating group of the molecule A and the electron-accepting group of the molecule B, which constitute the monolayer 21 on the substrate 3, and as shown in FIG. As shown in (1), the molecule B is deposited on the monolayer 21 of the molecule A while the electron-accepting groups are arranged toward the monolayer 21. At this time, if the temperature of the substrate 3 is set to a temperature at which the molecules A and B are adsorbed but the molecules B are hardly adsorbed to each other, the monomolecular layer 21 of the molecule A is placed on the monolayer 21 as in the previous step. A monolayer 22 of molecule B is formed. When the formation of the monomolecular layer 22 is completed, the shutter 9
Is closed, and the molecules B remaining in the vacuum chamber 2 are exhausted by a vacuum pump.

Subsequently, by opening the shutter 8 on the K cell 5 to allow the gasified molecules A to reach the substrate 3 and appropriately setting the temperature of the substrate 3 at that time, as shown in FIG. Then, a monolayer 23 of the molecule A is formed on the monolayer 22 of the molecule B in the same manner as described above.

Thereafter, by repeating the above-described steps of forming the monomolecular layers 22 and 23 alternately, a diacelenium multilayer film having a structure in which monomolecular layers of the molecule A and monolayers of the molecule B are alternately laminated can be obtained. .

Thereafter, the diacetylene multilayer film is irradiated with light such as ultraviolet rays through the light irradiation window 14 shown in FIG. As a result, the multilayer film is polymerized, and FIG. 2 (d)
A polydiacetylene film 24 as shown in FIG. FIG. 2 schematically shows the state of adsorbing molecules in the film, and the deposition is not necessarily in this shape, and various adsorption and deposition forms are possible.

According to this embodiment, as described above, a structure in which different molecules A and B are periodically distributed along the film thickness direction, that is, a polydiacetylene film having a precisely controlled superlattice structure is easily obtained. be able to. Further, since this embodiment is a dry process in a vacuum, a high-quality film with less defects can be obtained as compared with the LB method.

 FIG. 3 is a film forming process diagram of a second embodiment of the present invention.

This embodiment is different from the first embodiment in that each monomolecular layer is deposited while performing light irradiation instead of performing light irradiation last. That is, first, as shown in FIG. 3A, a monomolecular layer 21 of the molecule A is deposited on the substrate 3 in the same manner as in the first embodiment. Subsequently, a monolayer 22 of molecule B is deposited on the monolayer 21 in the same manner as shown in FIG.
Is polymerized by light irradiation to form a polydiacetylene film 31 as shown in FIG. 3 (b). After that, molecules A and B are alternately deposited while similarly irradiating light.
Thereby, as shown in FIG. 3 (c), FIG.
A high-quality polydiacetylene film 32 having a superlattice structure similar to that described above is obtained. FIG. 3 schematically shows the state of adsorbing molecules in the film. Actually, the deposition is not necessarily performed in such a shape, and various adsorption and deposition forms may be present.

FIG. 4 is a film forming process chart of the third embodiment of the present invention. Here, a method for manufacturing a polydiacetylene film using diacetylene molecules will be described as an example.

In this example, first, an electron-donating group was used. And electron accepting groups A diacetylene molecule (hereinafter, referred to as molecule C) having both of the following is prepared and used as a solid source 11 in FIG.
Put in. Then, the solid source 11 is gasified in the K cell 5 while keeping the vacuum chamber 2 at a high vacuum.

Subsequently, the shutter 8 on the K cell 5 is opened to allow the gasified molecules C to reach the receptive substrate 3. Then, since the adsorbing force acts between the electron-donating group of the molecule C and the electron-accepting substrate 3, as shown in FIG. While the groups are arranged on the substrate 3 side with the electron-accepting group facing the opposite side to the substrate 3,
It accumulates.

Further, the gasified molecules C reach the substrate 3 one after another. Then, an adsorption force acts between the electron-accepting group of the molecule C previously deposited on the substrate 3 and the electron-donating group of the molecule C that has reached the substrate 3 later, so that the temperature of the substrate 3 is appropriately set. By doing so, the molecules C are sequentially deposited on the substrate 3 while being arranged in a certain direction as shown in FIG. 4 (b).
By continuing this step, a diacetylene film 41 having strong molecular orientation as shown in FIG. 4 (c) can be obtained.

Thereafter, the diacetylene film is further irradiated with light such as ultraviolet rays through the light irradiation film 14. Thus, the diacetylene film is polymerized, and a polydiacetylene film 42 as shown in FIG. 4 (d) is obtained. FIG. 4 schematically shows the state of adsorbing molecules in the film. Actually, the deposition is not necessarily performed in such a shape, and various adsorption and deposition forms may be present.

According to this embodiment, a polydiacetylene film having a structure in which the molecular orientation is precisely controlled as described above can be easily obtained. Further, this embodiment is different from the first and second embodiments described above.
Since the process is a dry process in a vacuum as in the case of the first embodiment, a high-quality film with less defects can be obtained as compared with the LB method.

FIG. 5 is a film forming process chart of a fourth embodiment of the present invention.

In this embodiment, the molecules C are sequentially deposited while performing light irradiation instead of performing light irradiation last in the third embodiment described above. That is, first, as shown in FIG. 5 (a), molecules C are deposited on the substrate 3 in the same manner as in the third embodiment. Subsequently, FIG. 4 (b),
As shown in (c), molecules C are successively deposited, and these molecules are polymerized one after another by light irradiation as shown in FIGS. 5 (b) and (c). This allows
As in FIG. 4D, a high-quality polydiacetylene film 51 having a structure with controlled molecular orientation is obtained. FIG. 5 schematically shows the state of adsorbing molecules in the film. Actually, the deposition is not necessarily performed in such a shape, and various adsorption and deposition forms may be present.

The diacetylene molecule used in each of the above-described examples was used.
A, B and C are generally diacetylene molecules (RC = CC-
It can be obtained by adding an electron donating or electron accepting group to the side chains R and R 'of R'). Examples of the electron donating group include NH ₂ , N (CH ₃ ) ₂ , N (C ₂ H ₅ ) _2, and electron donating groups as shown in FIG. Examples of the electron accepting group include NO ₂ , CN, I, OH, O, Br, Cl, and an electron acceptor as shown in FIG. 6 (b).

In addition, the polydiacetylene film obtained in each of the above-described examples is a chain conjugated polymer and has a good quantum wire, so that the di-acetylene film constituting the main part of the molecules A, B, and C can be used. By appropriately selecting acetylene,
A non-linear optical film having good characteristics can be obtained. In particular,
As shown in FIG. 2 (d) and FIG. 3 (c), in the case where the different molecules A, B, have a periodic distribution structure alternately arranged along the direction of the polymer chain, a more favorable nonlinearity is obtained. Optical properties are obtained. An example of a diacetylene (diacetylene diameter compound) molecule suitable for such a nonlinear optical material is shown in FIGS. 7 (a) and 7 (b). Of course, the present invention is not limited to diacetylene-based compounds, and various organic materials can be used.
Among them, FIG. 8 shows an example of constituent molecules of a conjugated polymer suitable for a nonlinear optical material.

Further, in the above-described embodiment, an electron-accepting substrate is used as the substrate 3, but an electron-donating substrate may be used. In this case, in FIGS. 2 and 3, it is only necessary to switch the order in which the molecules A and B reach the substrate 3, and in FIGS. 4 and 5, only the direction of the molecule C is reversed. In any case, there is no difference in characteristics between the films finally obtained. As the electron-accepting or electron-donating substrate, a P-type or N-type semiconductor substrate may be used, or an electron-accepting or electron-donating layer may be formed on a normal substrate surface in advance. Is also good. Alternatively, a liquid crystal alignment film or an LB film may be formed on the surface of the substrate in advance, or an organic crystal may be used as the substrate, and the film may be formed using these as a base. Before the film formation, the substrate may be subjected to processes such as reactive etching, sputter etching, and thermal cleaning, so that the adsorbing force between the substrate and the molecules can be further increased.

Further, in the embodiment shown in FIGS. 2 and 3, the molecules A and B may each have three or more groups of the same type, or not only two or more types of molecules A and B, but also Many types of molecules such as A, A 'and molecules B, B' may be alternately stacked. Similarly, in the embodiment shown in FIGS. 3 and 4, the molecule C has two different groups.
One or more molecules may be provided, or not only one type of molecule C but also various types of molecules such as C and C 'may be sequentially deposited. This makes it possible to form a film having a higher degree of freedom.

In the case where a plurality of types of molecules are used, they may simultaneously reach the substrate to form a mixed layer of a plurality of molecules.
As a result, for example, at least one kind of molecule is set as a nonlinear optical molecule as shown in FIG. 7, and at least one other kind of molecule is set as a monomer for forming a polymer having strong mechanical strength such as MMA, HEMA, and diacetylene. For example, a strong film having nonlinear optical characteristics can be obtained.

In the above-described embodiment, the solid source of the organic molecule is K
Although gasification is performed in the cell, gas molecules may be introduced into the vacuum chamber by a gas introduction system from an external gas cylinder or ampule instead of this. The film forming apparatus used in the present invention includes the first
The invention is not limited to those shown in the figures, and ordinary vapor deposition equipment, ion plating equipment, sputtering equipment, ICB equipment and the like can also be used.

Further, in the above-described embodiment, the polymerization was performed by light irradiation. However, it is needless to say that the polymerization may be performed by heating, or the organic film of the monomer may not be polymerized depending on the application. .

Further, in the above description, molecules are deposited by using the adsorbing force between the electron-accepting group and the electron-donating group, but the chemical bonding force between the groups may be used. That is, organic molecules having reactive groups (for example, OH group and COCl group) are gasified in a vacuum chamber to reach a substrate, and each molecule is bonded and deposited by a chemical reaction between groups of adjacent molecules (Japanese Patent Application Akira
63-3895, JP-A-1-180531). Then, it is further polymerized by light irradiation or heating. In this case, a molecule to which two or more reactive groups are added and a molecule to which two or more groups different from this molecule are added may be made to reach the substrate alternately. Thus, a high quality organic film with a precisely controlled film structure can be obtained by utilizing the chemical bonding force between the groups.

〔The invention's effect〕

As described above, according to the present invention, an organic film having an extremely precisely controlled film structure, such as an organic superlattice film or an organic film having a strong molecular orientation, can be easily obtained. Moreover, since the present invention is a dry process in a vacuum, a high-quality film with very few defects can be obtained. Further, the mechanical strength can be increased by polymerizing the organic film deposited on the substrate.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a film forming apparatus used in each embodiment of the present invention, FIGS. 2 (a) to 2 (d) are film forming process diagrams of the first embodiment of the present invention, FIG. (A) to (c) are film forming process diagrams of the second embodiment of the present invention, FIGS. 4 (a) to (d) are film forming process diagrams of the third embodiment of the present invention, FIG. (A) to (c) are film forming process diagrams of the fourth embodiment of the present invention, and FIGS. 6 (a) and (c) are examples of electron donors and electron acceptors usable in each of the above embodiments. FIGS. 7 (a) and 7 (b) are views showing an example of a diacetylene-based compound that can be used in each of the above Examples, and FIG. 8 is used for producing an organic nonlinear optical film in the present invention. It is a figure which shows an example of a possible organic material other than a diacetylene type compound. 2 ... Vacuum chamber, 3 ... Substrate, 5,6,7 ... K cell,
8, 9, 10 Shutter, 14 Light irradiation window, 21, 22, 23 Monolayer, 24 Polydiacetylene film 31, 32 Polydiacetylene film, 41 Diacetylene film 42: Polydiacetylene film, 51: Polydiacetylene film.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H01L 51/00 H01L 29/28 (56) References JP-A-61-202420 (JP, A) JP-A-61-124122 (JP, A) "Vacuum," Vol. 30, No. 11, (1987-11-20), pp. 146-64. 853-864, "Chemistry and Industry", Vol. 40, No. 10, (1987-10-1), pp. 157-864. 826-895 (58) Fields investigated (Int.Cl. ⁶ , DB name) H01L 21/203 H01L 21/363 H01L 51/00 C30B 29/54 C23C 14/12

Claims (4)

(57) [Claims] A first organic molecule having two or more electron donating groups and a second organic molecule having two or more electron accepting groups are gasified in a vacuum chamber and alternately formed on a substrate. The monolayer made of the first organic molecule and the monolayer made of the second organic molecule on the substrate by the attraction force between the electron donating and electron accepting groups adjacent to each other. A method for producing an organic film, wherein the organic film is alternately deposited. 2. An organic molecule having at least one of both an electron-donating group and an electron-accepting group is gasified in a vacuum chamber to reach a substrate, and an electron-donating property and an electron-accepting property adjacent to each other are obtained. A monomolecular layer made of the organic molecules having a uniform molecular orientation on the substrate by an adsorbing force between the groups. 3. A first organic molecule having two or more first reactive groups and a second organic molecule having two or more second reactive groups are gasified and alternately formed in a vacuum chamber. A monomolecular layer of the first organic molecule and the second organic layer on the substrate by chemical reaction between the first reactive group and the second reactive group adjacent to each other; A method for producing an organic film, comprising alternately bonding and depositing monomolecular layers composed of molecules. 4. An organic molecule having at least one of both a first reactive group and a second reactive group is gasified in a vacuum chamber to reach the substrate, and the first molecules adjacent to each other are gasified. Forming a monolayer of the organic molecules having a uniform molecular orientation on the substrate by a chemical reaction between the reactive group and the second reactive group; Method.