JPH03146129A - Formation of thin organic membrane - Google Patents

Abstract

PURPOSE:To easily manufacture a high oriented org. membrane by laminating org. substances such as polymerizable org. compound on a substrate having an anisotropic molecular orientation membrane by resistance heating vapor deposition method, light CVD method, etc. CONSTITUTION:Org. substances are laminated on the substrate having an anisotropic feature to form a thin org. membrane. The molecular orientation membrane having the ability to orient liq. crystal and a rhombic vapor deposition membrane such as SiO and MgF2 membranes are suitable for use as the aforesaid substrate. By way of example, the org. substances to be laminated on the substrate may be diacetylene derivative, fatty acid such as stearic acid, esters and coloring matter. The method suited for laminating the org. substances may, for example, be by resistance heating vapor deposition, electron beam vapor deposition, cluster ion beam, sputtering, ion plating and light CVD.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD 1 The present invention relates to a method for producing an organic thin film, and particularly to a method suitable for producing a highly oriented organic thin film. [Prior Art] In recent years, attempts have been made to utilize organic substances as conductive materials, chromic materials, photoelectric conversion materials, nonlinear optical materials, optical recording materials, etc., but the success or failure of these efforts depends on the The organic material is a film with good molecular orientation (
It is no exaggeration to say that it depends on whether or not it can be stably and easily supplied as a film in which molecules are oriented in a specific direction. The vacuum evaporation method and the LB method are well known as general methods for producing organic thin films, but the methods to date have not necessarily been successful in producing thin films with good molecular orientation. do not have. For more information on the LB method, see Chemistry Review No. 40. Discussed on pages 82 to 104 of "Molecular Assemblies - Their Organization and Function", Nippon Kagaku Metals, Gakkai Publishing Center (published on May 25, 1980). It has long been known that by using the LB method, it is possible to form a film in which molecules are oriented in an orderly manner in a direction perpendicular to the film surface (an LB film made of fatty acids such as stearic acid corresponds to this). Also, recently, some compounds
It has also become possible to produce an LB film with good orientation in the in-plane direction. For example, for highly oriented polydiacetylene compounds, Thin So] id
Films) 168 (+989)! 41-149. It has been published on . However, it is extremely difficult to orient molecules in a specific intended direction, and the greater the cumulative number of layers (film thickness), the more difficult it becomes to orient the molecules in the entire film. . High orientation in the above paper 1. In film B, the main chains of polydiacetylene are simply aligned in a specific direction within a domain several millimeters in size. For more information, please visit Journalon
Colloid Interface Science (J, Co11
oid, Interface Sci, ) 101,1
29 (1984). It is described in. Furthermore, it is generally well known that organic thin films are produced by vacuum evaporation. However, when producing a highly oriented film,
There is a problem in that it is difficult to control the deposition conditions that determine the quality of orientation, and it is largely dependent on the material and substrate. Cleavage planes of alkali halide single crystals such as potassium chloride,
Although there have been some successful examples of depositing organic molecules onto the surface of metals such as Pt(111), the result has been that the film structure largely depends on the substrate temperature, deposition temperature, and deposition rate. In addition, as a conventional example of this type, Japanese Patent Application Laid-Open No. 59-62608
can be mentioned.

[Problem to be solved by the invention]

Conventionally, when producing highly oriented films of organic materials, especially B
In film production, sufficient consideration was not given to the substrate. In manufacturing methods using vacuum evaporation and other dry processes, substrates have been selected using the same concept as inorganic materials. The purpose of the present invention is to easily produce a highly oriented organic thin film using a vacuum evaporation method or an LB method by selecting an appropriate substrate.
The aim is to provide a stable supply.

[Means to solve the problem]

The above purpose is for substrates with anisotropy in surface shape, such as obliquely deposited films, gratings, and substrates etched with ions from a specific direction, and molecules that are constant, such as LB films, vacuum-deposited organic thin films, and stretched polymer films. Thin films that are oriented in the same direction, substrates that are moving or vibrating, or rubbed films (
This can be easily achieved by forming an organic thin film using a dry process such as a vacuum evaporation method using a substrate such as a substrate as a base substrate and an organic compound to be oriented and grown on the substrate as a deposition source. Alternatively, it can be achieved by accumulating the organic film formed on the substrate described in 1 above at the gas-liquid interface by a method such as a vertical dipping method or a horizontal deposition method. In either method, it is necessary to maintain the substrate at a specific temperature depending on the type of organic molecule. Also, vacuum evaporation method and I. ■If the highly oriented organic thin films of specific molecules formed by the three methods are films in which the molecules are oriented in a certain direction,
It can be used as a base substrate in the present invention. Examples of thin film forming methods using dry processes include resistance heating evaporation, electron beam evaporation, molecular beam evaporation, cluster ion beam evaporation, ion beam evaporation, sputtering, ion plating, and CVD. LB films such as fatty acids are originally oriented in the direction perpendicular to the film surface (
However, some LB films also tend to have molecules oriented in a direction parallel to the film surface. An example of such a film is a film made of a polydiacetylene compound represented by the chemical formula %. Suitable materials for the organic deposited film include phthalocyanine derivatives, fatty acids such as stearic acid, perfluorocarboxylic acids, polyethylene, n-hexatriacontane (n-CagHヮ), and polyvinylidene fluoride. A rubbed film is a film that is coated with 5iOz on the surface of a glass substrate, etc.
It is a film that obtains orientation by forming a polymer film of (spin-on glass), polyimide, or polyvinyl alcohol (PVA), and rubbing the surface of the film in one direction with a cloth or the like, that is, "rubbing." Regarding cloth,
Materials made of silicone fiber, Teflon fiber, real cotton thread, etc. can be used, but cloth made of silicone fiber (silicon cloth) is most suitable. It is preferable to use such a cloth to rub the substrate surface in one direction only, particularly in one direction only. The most typical obliquely deposited film is SiO. Any other possible oxides, fluorides or Au
It is also possible to use metals such as or AI and their oxides. The effect of orientation is large when the value of the deposition angle measured from the normal is between 45° and 85°. As a grating, a grating in which grooves are formed only in a certain direction, such as a diffraction grating, is effective. A stretched polymer film has an orientation ability by stretching a polymer film with a long main chain by about 200%, which can be done manually. A typical example is PVA. For highly oriented organic thin films formed by vacuum deposition on a substrate that is moving or vibrating relative to the deposition source, this is possible, for example, by installing a movable or vibrating substrate holder in a vacuum container. . Conversely, the evaporation source may be movable or vibrating. Typical examples of organic compounds formed on the substrate include diacetylene derivatives, phthalocyanine derivatives, fatty acids such as stearic acid, alcohols and esters, and pigments such as merocyanine and hemicyanine. Examples of diacetylene derivatives include hydrocarbons such as 2,4-hexadiyne, 2,4-hexadiyne-1,6
-Alcohols such as diol, 3,5-octadiyne-1,8-diol, carboxylic acids, sulfonic acids, and carbamate esters of these alcohol compounds, 1,6-di(N-carbazoyl)-2,4 Examples include heterocyclic compounds such as -hexadiyne and 1,4-dipyridyl-1°3-butadiyne, acids such as 1,3-butadiyne-carboxylic acid, and their esters, amides, and salts. These organic compounds are
Two or more types can be used in combination if necessary.

[Effect]

First, a highly oriented LB film or a highly oriented organic vapor deposited film, a rubbed film, prepared on the back of a glass substrate or silicon substrate,
An obliquely deposited film, a grating, or a moving or vibrating substrate is placed in a vacuum container together with a deposition source. By selecting appropriate substrate temperature, evaporation temperature, and evaporation speed,
Organic molecules become oriented and crystals grow. If it is necessary to make it into a polymer, it is then polymerized using ultraviolet light or the like at an appropriate temperature. When using the LB method, a highly oriented LB film, a highly oriented organic evaporated film, a rubbed film, an oblique evaporated film, or a grating prepared on a glass substrate or silicon substrate is used as the base substrate, and the film is formed at the gas-liquid interface. Organic molecules can be oriented by accumulating organic thin films at an appropriate temperature. [Examples] Hereinafter, the present invention will be explained in detail with reference to Examples. Specific examples will be described using l and n, but the invention is not limited to this example, and other substrates may be used as long as they have anisotropy in shape and physical properties. The substrate or other combinations (substrate and organic material formed) may be used. The material to be formed as a highly oriented organic thin film is not limited to that of this example. (Example 1) A case will be described in which a highly oriented polydiacetylene film is formed by vacuum evaporation using a grating as a substrate. Polydiacetylene is very suitable for evaluating molecular orientation. A diacetylene monomer represented by the following formula was used (hereinafter abbreviated as 3BCMU). R-(jC-CEC-R' (R, R' = (CHz)s OCON HCHz
COOC4Hs) Photolitho
A grating with a pitch of 1,000 gratings/diameter was placed as a substrate in a vacuum container together with a deposition source. The vapor deposition apparatus is a typical one using resistance heating. I x 10-r″Torr inside the vacuum container
r or less, with a deposition rate of about 1OA/see or less and a film thickness of 100
0 diacetylene thin films were formed. The orientation of molecules was increased by setting the substrate temperature during vapor deposition to 50°C. After vapor deposition, 38
A polymer thin film of CMU was obtained. As a result of optically examining the crystallinity of the thin film, we found that the dichroic ratio, here the ratio of the absorbance in the main chain direction of polydiacetylene to the absorbance in the perpendicular direction (wavelength 62
A polydiacetylene thin film with good orientation (0 nm) of 5 could be produced. It was confirmed that the molecules were oriented in the direction of the grooves of the grating. The results are shown in FIG. In the figure, A is the absorption spectrum in the main chain direction, and B is the absorption spectrum in the direction perpendicular to the main chain direction. Furthermore, even when an organic thin film was formed on a stretched polymer film such as polyvinyl alcohol, it was confirmed that the molecules grew in a similar oriented manner. (Example 2) Next, a case will be described in which an organic substance is vacuum-deposited on a substrate that is moving with respect to a deposition source. CTAB (Cetyl Trimethyl Ammonium Bromide: Cetyl Trimethyl An+a+o) is a surface treatment agent for glass substrates.
niuIllBromide) CHxcc Hz)xi N (CHa)i”B r-
of CH3Cl solution, taken out and dried. In the film thus obtained, the carbon chains of CTAB are exposed on the surface. The solution is diluted to a concentration that does not allow CTAB to precipitate as white crystals on the substrate. If precipitation occurs, wash it off gently with ethyl alcohol, etc. before use. Even if the substrate surface is washed with ethyl alcohol, the hydrophobicity of the substrate surface is maintained. This can be confirmed by looking at the formation of water droplets. A diacetylene monomer expressed by a linear formula (hereinafter abbreviated as 4BCMU) was vacuum-deposited onto this substrate by resistance heating. R-CEC-(, EC-R' (R, R'=-(CH,)40CONHCHICOOC
4H9) A glass substrate is placed in a substrate holder that can be rotated at a constant speed within a vacuum container at a position away from the center of rotation. When the substrate is rotated over the deposition source, a diacetylene thin film is formed. If the glass substrate is located far from the center of rotation of the holder,
In addition, if the area of the curtain plate is small, the state within the substrate is almost the same as if the vapor was deposited while moving in one direction. The pressure inside the vacuum container was reduced to I x 10-' Torr or less, the rotation speed of the substrate holder was set to 1 Orpm, and 4BCM was applied.
The U diacetylene monomer was deposited to a film thickness of 1000 g/see at a deposition rate of about 5 g/see or less. The orientation of molecules was increased by setting the substrate temperature during vapor deposition to 50°C. After vapor deposition, 4
A polymer thin film of B CM U was obtained. As a result of measuring the absorption spectrum with a spectrophotometer and examining the crystallinity of the thin film, it was possible to produce a polydiacetylene thin film with a dichroic ratio of 5 and good orientation. It was confirmed that the molecules were oriented in the direction of movement of the substrate. Furthermore, a highly oriented film with a dichroic ratio of 3 could be produced by attaching an ultrasonic vibrator to the substrate and ultrasonically vibrating the substrate during vapor deposition under the same conditions as in -I. (Example 3) Next, a case will be described in which an obliquely deposited film is used as a substrate. By depositing silicon monoxide (SiO) on a glass substrate at an angle of 60° from the normal direction of the substrate,
A SiO oblique evaporation film was formed. On this substrate, the substrate temperature is 100°C, the deposition rate is about 5 people/sec or less, and the film thickness is 1000.
Copper phthalocyanine was further vacuum deposited under human conditions. As a result of measuring the molecular orientation using a spectrophotometer, the dichroic ratio was 4.
It was found that an oriented film was obtained. Moreover, it was also found that the orientation of molecules changes little by little depending on the deposition angle during formation of the obliquely deposited film. In particular, 4
The effect on molecular orientation was large in the range of 5° to 85°. Furthermore, even when an organic thin film is formed on a substrate that has been ion-etched from a specific direction, it was confirmed that the molecules grow in a similar oriented manner. (Example 4) An example in which highly oriented (1) and (B) films were produced using a grating substrate will be described. The experiments were conducted using polydiacetylene, which is very often used as a material for LB films and is suitable for evaluating molecular orientation. L
The apparatus for producing the B film is a general one using a Teflon container. All experiments were conducted in a clean room. First, we start with diacetylene derivative Hebutacosa 1, which is a monomer film-forming molecule.
0.12 Jinoic acid (heptacosa)
-10,12-diynoid acid)CH, (c
o2) □, -(, EC-(, :C-(CH2), C0O
H Nohenzen solution (# degree 2.28 x 10-'M) wo,
Drop 70μQ on the air-water interface and apply approximately 400CI1 on the water surface.
Of the area of 12? 11 molecular membranes were produced. The aqueous phase is ultrapure water (
The resistivity is about 17 MΩCnl (however, if necessary, ions such as L l ” gCd2+ may be added to the aqueous phase), and the laboratory temperature is room temperature. After developing the solution, it is placed on 1 m of water. In order to prevent the spray molecule film from being destroyed, a surface pressure of 25 cm was applied to the barrier at a compression rate of 20 cm2/min.
The monolayer was compressed from two opposing directions to mN#s. Two methods were used to accumulate the molecular film. One is the most common accumulation method as the LB method, which is the so-called vertical immersion method in which the substrate is taken in and out in a direction perpendicular to the water surface. Here, a grating substrate heated to 50°C (pitch 1000 lines by photolithography) mm
, area 2×2CII+2), approximately] mm/mi
Monolayers were accumulated by moving under −E at a speed of n. In addition, the aqueous phase was added to a concentration of 2. OX to'''3M Cd(OH)
When made into an aqueous solution, accumulation was particularly easy. At that time, adjust the pll to around 7 using NaOH. Another method is called the horizontal attachment method.
This is an accumulation method in which the substrate is placed approximately horizontally to the water surface and the monomolecular film is transferred to the substrate as is. HexaIIlethydisila-zane (CH,+)aSiNHSi(CHa)a, which is a chemically adsorptive silane-based coupling material, was adsorbed onto the substrate and subjected to hydrophobization treatment. Also in the horizontal deposition method,
With the grating substrate heated to 50°C,
- Each time the layers were laminated, the temperature was increased by more than 10 minutes to ensure that the temperature of the substrate was transferred to the film. After producing the LB method with up to 50 layers accumulated using each method, the substrate was stored for 24 hours while keeping the substrate temperature at 35° C. in consideration of rearrangement of diacetylene molecules. Thereafter, ultraviolet rays generated from an ultra-high pressure mercury lamp (200 W) were irradiated for 30 minutes to polymerize diacetylene in the same phase to obtain a polydiacetylene thin film. The fact that it has become a bomber can be easily determined from the fact that the membrane is colored. As a result of optically examining the crystallinity of the thin film and measuring its spectrum, it was possible to produce a polydiacetylene thin film with a dichroic ratio of 5 and good orientation. It was confirmed that the molecules were oriented in the direction of the grooves of the grating. The method of accumulating a monomolecular film is not an essential problem with respect to orientation, but the optimum conditions such as temperature, time, speed, etc. must be determined depending on each accumulation method (including accumulation methods other than those listed above). It is preferable to choose. In particular, in the horizontal deposition method, since a monomolecular film is accumulated only from one direction, it must be noted that the structure immediately after accumulation will be different from that in the vertical dipping method. When a polydiacetylene thin film is prepared using the conventional method (using an untreated glass substrate without temperature control), 1
Although it is an accumulation of monomolecular films having a domain structure with a size of 0 μIl to lllll11, it was found that the orientation of molecules could be controlled by using a grating as a substrate. Furthermore, using the polydiacetylene thin film formed by vacuum evaporation in Examples 1 and 2 as a substrate, it is also possible to further layer other organic molecules thereon by the LB method under the above conditions to produce a highly oriented film. there were. A highly oriented film could be similarly produced using a rubbed substrate, an obliquely evaporated film, and a stretched polymer film. (Example 5) Film thickness: 1000, dichroic ratio: 5, produced by the method of Example 2
The third-order nonlinear optical properties of highly oriented polydiacetylene films were evaluated. The actual measurement system is shown in Figure 2. In the experiment, Q-s 1tch Nd
3”: YAG laser 2 wavelength 11064n, 1.0pp
s, a fundamental wave of several 10+nJ/pulse is irradiated, and the third harmonic intensity with a wavelength of 355 nm is OMD (Optical multi-channel detector: 0ptical Mul
The third-order nonlinear optical constant χ3 of polydiacetylene was evaluated by detecting with a Tichannel Detector) 3. Incident light beam (φ~]Oim) 4
was linearly polarized light, which was focused on the sample by a lens 6. The fundamental wave is removed by an infrared cut filter 5, and the harmonics generated from the sample are transmitted through a filter 7 and sent to a polyglometer 8.
It is spectrally separated by The data detected by OMD3 is 1
After integrating and averaging 000 pulses, the data is taken into the computer 9 and processed. Maker Fringe (M
As a result of measurement using the Aker Fringe method, χ377 in the direction parallel to the main chain of polydiacetylene is approximately 1X
l0−”esu, 1 of χ3□ in the direction perpendicular to the main chain
The size was 0 times or more. Here, 10 in the figure is a controller, 11 is a plotter, 12 is a storage device, and 13 is an oscilloscope. Furthermore, similar results were obtained for highly oriented films prepared by methods other than Example 2. Evaluation of the second-order nonlinear optical constant χ2 was also possible using the same experimental system. (Example 6) Film thickness: 1000, dichroic ratio: 5, produced by the method of Example 2
A liquid crystal display device as shown in FIG. 3 was fabricated using the highly oriented polydiacetylene film as the molecular alignment film. First, the highly oriented polydiacetylene film of Example 2 is applied to the molecularly oriented film 24 on the indium oxide (InxOa) film 24.
Formed as. These two transparent electrodes are pasted on a glass plate 25, facing each other at an interval of 10 to 100 μm,
During this time, a small amount of nematic liquid crystal 21 was injected and the surrounding area was sealed with epoxy resin to produce a sandwich-shaped cell. Furthermore, if polarizing plates 26 made of PVA transparent films adsorbed with iodine are pasted on both sides of the cell to create a reflective liquid crystal display element, a reflective plate 27 is provided on the outside of one polarizing plate. Ta. When a voltage was applied to this device, it was confirmed that it operated as a liquid crystal display device. Moreover, it has better alignment control than conventional molecular alignment films, and since it does not rely on rubbing, there is no fear of destruction of elements such as transistors. It was confirmed that even when an inorganic vapor-deposited film such as a SiO film was produced by the method of Example 2, it operated as a liquid crystal display element in the same way as an organic film. Effects of the Invention 1 According to the present invention, it is possible to easily produce a highly oriented organic film by a vacuum evaporation method or an LB method. Furthermore, even a substance that is difficult to form into an alignment film by itself can be oriented with respect to the underlying chain plate by using an existing alignment film or an anisotropic substrate.

[Brief explanation of the drawing]

FIG. 1 is a light absorption characteristic diagram of an alignment film according to an embodiment of the present invention, FIG. 2 is a block diagram of a YAG laser harmonic generator, and FIG. 3 is a cross-sectional view of a liquid crystal device according to an embodiment of the present invention. It is. 'l/Diagram back and front

Claims (28)

[Claims] 1. A method for producing an organic thin film, comprising laminating an organic substance on a substrate having anisotropy. 2. 2. The method for producing an organic thin film according to claim 1, wherein the substrate having anisotropy is a molecular alignment film. 3. 3. The method for producing an organic thin film according to claim 2, wherein the molecular alignment film has the ability to orient liquid crystal. 4. The method for stacking the organic material is resistance heating evaporation method, electron beam evaporation method, molecular beam evaporation method, cluster ion beam method, ion beam evaporation method, sputtering method, ion plating method, photoCVD method, or plasma CVD method. 2. The method for producing an organic thin film according to claim 1, wherein the organic thin film is formed by at least one of these methods. 5. 2. The method for producing an organic thin film according to claim 1, wherein the method for laminating the organic substance is a method for accumulating at least one layer of the film formed at the gas-liquid interface on the substrate. 6. 2. The method for producing an organic thin film according to claim 1, wherein the substrate having anisotropy is an obliquely deposited film. 7. 7. The method for producing an organic thin film according to claim 6, wherein the obliquely deposited film is a SiO film or a MgF_2 film. 8. 2. The method for producing an organic thin film according to claim 1, wherein the anisotropic substrate is a grating. 9. 2. The method for producing an organic thin film according to claim 1, wherein the anisotropic substrate is an organic film in which molecules are oriented in a certain direction. 10. 10. The method for producing an organic thin film according to claim 9, wherein the organic film in which molecules are oriented in a certain direction is a film that is formed at a gas-liquid interface and then transferred onto the same substrate. 11. 10. The method for producing an organic thin film according to claim 9, wherein the organic film in which molecules are oriented in a certain direction is a film formed by a vacuum evaporation method. 12. 10. The method for producing an organic thin film according to claim 9, wherein the organic film in which molecules are oriented in a certain direction has anisotropy within the film plane. 13. 2. The method for producing an organic thin film according to claim 1, wherein the substrate having anisotropy is a substrate subjected to a rubbing treatment. 14. 2. The method for producing an organic thin film according to claim 1, wherein the anisotropic substrate is a substrate that has been ion-etched from a specific direction. 15. A method for producing an organic thin film, characterized in that a substrate moves or vibrates when an organic substance is laminated. 16. A method for producing an organic thin film characterized by vacuum deposition from a deposition source that moves or vibrates with respect to a substrate. 17. 16. The method for producing an organic thin film according to claim 15, wherein the substrate is subjected to ultrasonic vibration. 18. 16. The method for producing an organic thin film according to claim 1, wherein the temperature is raised above room temperature when the organic substance is laminated. 19. 10. The method for producing an organic thin film according to claim 9, wherein the organic film in which molecules are oriented in a certain direction is a film made of a diacetylene derivative or a polydiacetylene derivative. 20. 16. The method for producing an organic thin film according to claim 1, wherein the organic substance to be laminated is a polymerizable organic compound. 21. 21. The method for producing an organic thin film according to claim 20, wherein the organic substance to be laminated is a diacetylene compound. 22. The organic substance to be layered has the general formula CH_3(CH_2)_l-C≡C-C≡C-(CH_
22. The method for producing an organic thin film according to claim 21, wherein the organic thin film is a diacetylene derivative represented by 2)_kCOOH (in the formula, l and k represent any integer from 1 to 18). 23. 21. The method for producing an organic thin film according to claim 20, wherein after the organic material is laminated, the formed film is polymerized by irradiation with ultraviolet rays, γ rays, or electron beams or heat treatment. 24. 21. The method for producing an organic thin film according to claim 20, wherein the temperature during polymerization is raised to above room temperature. 25. A molecular alignment film formed by the method according to claims 1 and 10. 26. A molecular alignment film characterized in that it is formed by depositing SiO or MgF_2 on a moving or vibrating substrate. 27. A liquid crystal display device comprising the molecular alignment film according to claim 25 or claim 26. 28. An organic thin film having nonlinear optical properties, characterized in that it is formed by the method according to claim 1 or claim 19.