JPH0321019A - Organic crystal and its manufacture - Google Patents

Abstract

PURPOSE:To enable micro-processing of an organic crystal by a method wherein mixed gas of halogenized carbon or halogenized hydrocarbon and oxygen is used while one of electrodes of reactive ion etching apparatus is cooled and the organic crystal is mounted on the cooled electrode to be etched. CONSTITUTION:Gas used for reactive ion etching is mixed gas of halogenized carbon or halogenized hydrocarbon and oxygen while one of electrodes of a reactive ion etching apparatus is cooled and an organic crystal 3 is mounted on the cooled electrode directly or via an optional substrate 1 to be etched. That is, in order to eliminate difference in etching rate between resist being organic high polymer and the organic crystal, it is necessary to use mixed gas of halogenized carbon or halogenized hydrocarbon and oxygen while in order to prevent deterioration of the organic crystal one of the electrodes is cooled and the organic crystal is etched on the cooled electrode. Thus, various kinds of organic crystals can be micro-processed according to desired patterns.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing functional organic crystals by microfabrication, which is attracting attention mainly in the optoelectronic technology field, and an organic crystal obtained by the method. It is related to. In particular, it is usefully used as an organic nonlinear optical crystal optical waveguide suitably used in technical fields such as optical information processing, optical communication, and optical measurement and control.

In recent years, the development of functional organic materials such as nonlinear optical materials, organic conductors, and organic photochromic materials has been remarkable, and they are expected to play an active role in future optoelectronic technology. Such functional organic materials are often used in the form of crystals. In order to utilize such crystals in the field of optoelectronic technology, it is essential to perform fine patterning to control the flow of electrons and the propagation direction of light. However, such crystals cannot be directly patterned because their solubility and other properties are not changed by light, heat, electron beams, or the like.

On the other hand, processing methods applied to integrated circuit processing and the like are known for inorganic crystals such as semiconductors. This method involves forming a photosensitive polymer material on a substrate and patterning the photosensitive polymer material by changing its properties with light or electrons. For details, refer to ``Materials and Photosensitive Resins'' (Gakkai Publishing Center, 1979).

However, it has not been possible to apply this method to organic crystals. This is because the various conditions in the semiconductor microfabrication process, especially the etching conditions, are harsher than the heat resistance and chemical resistance of the organic crystal, resulting in deterioration and alteration of the organic crystal.

Furthermore, as semiconductor microfabrication processes are becoming increasingly finer, the conventional wet etching method is being avoided due to problems such as side etching and contamination, and dry etching is being promoted. Among these, reactive ion etching equipment is being actively studied because it can perform anisotropic etching. However, there have been no reports of etching patterned organic crystals coated with resist using this method. Although it is not an organic crystal, it is an example of slightly etching polyimide as an organic material (FD, Egiilo
et al, J, Vac, 'S'ci, Technol
．． , B3 (3), 813 (1985)).

This is because if the conditions used for ordinary active ion etching of inorganic crystals are applied to organic crystals, the temperature of the organic crystals exposed to strong plasma will rise, causing thermal deterioration or alteration. Furthermore, if normal inorganic crystal conditions are used, the difference in etching rate between the organic polymer used as a resist and the organic crystal cannot be compensated for, meaning that the resist will be etched at the same time as the organic crystal is etched. However, it has been extremely difficult to microfabricate organic crystals.

<Problems to be Solved by the Invention> 5 The present invention attempts to eliminate the drawbacks of the prior art, and aims to provide a method for producing a finely patterned organic crystal and a method for producing a finely patterned organic crystal. The purpose is to provide organic crystals.

<Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

(1) Applying a resist sensitive to light or electron beams onto an organic crystal, exposing and developing the resist into a desired fine pattern, and then etching the organic crystal using a reactive ion etching device. A manufacturing method for obtaining an organic crystal by using a reactive ion etching method, wherein the gas used for reactive ion etching is a mixed gas of halogenated carbon or halogenated hydrocarbon and oxygen, and one of the electrodes of a reactive ion etching device is A method for producing an organic crystal, which comprises cooling the electrode, placing the organic crystal directly or via an arbitrary substrate on the cooled electrode, and etching the organic crystal.

6 (2) An organic crystal having a pattern of convex portions or concave portions, which is obtained by the manufacturing method described in (1) above. '' In the present invention, any organic crystal can be used as long as it is an organic crystal, but organic nonlinear optical materials, organic conductors, organic photochromic compounds, and the like are particularly preferably used. For organic nonlinear optical materials, practically the second-order nonlinear optical constant χ
(2) is 1 × 1 0-10 esu or more, or the third-order nonlinear optical constant χ (3) is I X 1 0-14
esu or higher is desirable, and specific compounds with such optical constants include 2-methyl-4-nitroaniline, metanitroaniline, N-(4-nitrophenyl)(L)-prolinol, 2-( N,N-dimethylamino)-5-nitroacetanilide, 4゜nitropenzylidene-3-acetamin-4-methoxyaniline,
2-(N-prolinol)-5 nitropyridine, (-)
second-order nonlinear optical materials such as 2-(α-methylbenzylamino)-5-nitropyridine, and boridiacetylene,
Third order nonlinear optical materials such as charge transfer complexes are well known.

As organic conductors, charge transfer complexes such as tetrathiafulvalene-tetracyanoquinodimethane complex, bisethylene dithiotetrathiafulvalene-halogen complex, and phthalocyanines are well known.

Furthermore, as organic photochromic compounds, spiropyran compounds, spirooxazine compounds, azo compounds, fulgide compounds, indigo compounds, and the like are well known based on their basic molecular structures.

In addition to these, there are also substances used as scintillators and phosphors, such as anthracene, pyrene, perylene, and ferrocene, but these materials can be used if their functions can be utilized by microfabrication. It is not limited to.

In the present invention, resists sensitive to light or electron beams include various positive and negative resists commonly used in semiconductor microfabrication processes, as well as photopolymerization reaction, photocrosslinking reaction, and photosolubilization reaction. , various photosensitive polymer materials based on photodegradation reactions, or electrosensitive polymer materials can be used. Regarding these, see "Recording Materials and Photosensitive Resins" (Gakkai Publishing Center, 1979), "
Known examples are described in detail in "Photosensitive Polymers" (Kodansha, 1977).

According to the literature by F., D., EgiHo et al. listed in the prior art section, in the initial process of etching using CF4,
Highly reactive fluorine radicals are generated in the plasma, extracting hydrogen from organic compounds, and forming active carbon radicals or carbon-carbon double bonds.

By attacking the active site with oxygen radicals,
Eventually, volatile compounds (carbon dioxide, water, etc.) are activated and etching takes place.

On the other hand, when fluorine radicals attack active sites on an organic compound, inert C--F bonds are generated and etching no longer progresses. Based on the reaction mechanism described above, the inventors of the present invention believe that the number of bond breaks and the bond energy between resist 9, which is an organic polymer, and organic crystal, which is a molecular crystal, are different to form a volatile compound. As a result of actual research, they found conditions that would allow for a sufficient difference in etching rate to obtain the desired pattern and would not cause deterioration or alteration of the organic crystal, leading to the present invention. .

That is, the present invention is a method for manufacturing an organic crystal by etching the organic crystal using a reactive ion etching device, and in the manufacturing method, etching a resist that is an organic polymer and the organic crystal. In order to obtain a difference in rate, it is necessary to use a mixed gas of oxygen and halogenated carbon or halogenated hydrocarbon, and in order to prevent deterioration of the organic crystal, one of the electrodes is cooled; It is necessary to place the organic crystal on a cooled electrode and perform etching, or to place the organic crystal on an arbitrary substrate and place it on a cooled electrode for etching.

Furthermore, it is preferable that the voltage between the electrodes be 1 w/cXl or less. This is because when a voltage exceeding I W/cd is applied, the strong accelerating voltage causes high-energy radical species to attack the organic crystal, leading to deterioration of the organic crystal and at the same time causing physical etching. Go on,
This is because it may be difficult to provide etching selectivity.

Regarding reactive ion etching equipment, for example, Semiconductor World,
1985 years. Details in October issue, p155~.

In the present invention, the halogenated carbon or halogenated hydrocarbon includes CF4, CCl4, CHF3, C2F6
, C3F8, etc. can be used, and among them, CF4 is the most preferable.

In the present invention, when the mixed volume ratio of oxygen gas to halogenated carbon or halogenated hydrocarbon exceeds 80%, when this mixed gas is used for etching a low-molecular organic crystal, the surface of the organic crystal may deteriorate. There was a tendency to Further, if the mixed volume ratio of oxygen gas to 11 of halogenated carbon or halogenated hydrocarbon in the mixed gas is less than 2%, etching may be difficult to proceed. Therefore, in the present invention, a range of halogenated carbon or halogenated hydrocarbon/oxygen (volume ratio) from -20/80 to 98/2 is preferably used.

The electrode must be cooled to a temperature at which the organic crystal does not deteriorate due to heat, and during etching, the electrode must be cooled so that the temperature does not rise to at most the melting point of the organic crystal. The temperature varies depending on the organic crystal used, so it cannot be generalized, but it is preferable to maintain the temperature of the organic crystal at 30'C or less.

In addition, when placing an organic crystal on an electrode via an arbitrary substrate, any substrate can be used as long as it can hold the organic crystal. For example, A
Metal substrates such as I, Cu, and Si, glass substrates, and polymer substrates are preferably used.

Furthermore, if the organic crystal is dissolved by the resist solution during coating, an appropriate crystal protective layer may be provided between the resist that is sensitive to light or electron beams and the organic crystal. The material used for such a crystal protective layer may be any material as long as its solubility is different from that of the resist, but in particular metal materials such as aluminum, gold, copper, titanium, and chromium, inorganic dielectric materials such as Si02, Si3N4, etc. Polymeric materials such as polyvinyl alcohol, polyamide, cellulose resin, etc. are preferably used.

By the manufacturing method of the present invention, it is possible to obtain an organic crystal having a pattern of convex portions or concave portions formed by etching.

The organic crystal obtained by the present invention is characterized by being finely processed compared to mechanically processed ones. Although its fineness depends on the performance of the resist and photomask used, it is generally possible to process it to a fine width of 10 μm or less.

Furthermore, by using an electron beam resist, processing of 1 μm or less is also possible.

Organic crystals microfabricated by etching in this manner can be preferably used as optical waveguides. In this case, there are two methods: using the organic crystal itself as an optical waveguide, and using a material other than the organic crystal as an optical waveguide. An example in which the organic crystal itself is used as an optical waveguide is shown in FIG. 1 (in FIG. 1, 1 is the substrate and 2' is the optical waveguide of the organic crystal). In an optical waveguide having such a configuration, the substrate material must be selected so that the refractive index of the organic crystal forming the optical waveguide is greater than the refractive index of the substrate. In addition, the case where an optical waveguide is made of a material other than an organic crystal is shown in FIGS. 2 and 3 (
In FIGS. 2 and 3, 1 is a substrate, 2 is an organic crystal, and 3 is an optical waveguide made of a material other than the organic crystal. Fig. 2 shows an example in which an organic crystal is provided on a substrate and an optical waveguide is provided in the organic crystal, and Fig. 3 is an example in which an optical waveguide is provided only in the organic crystal without using a substrate. This is an example of a case. In optical waveguides having such configurations, it is necessary to select materials that form the optical waveguide so that the refractive index of the material is larger than the refractive index of the organic crystal and the substrate.

As materials with high refractive index and methods for forming optical waveguides, MgO2, TiO2, Zr
A method in which metal oxides such as 02 are formed into thin films by vapor deposition, and polymeric materials such as poly(tribromophenoxy 2-hydroxypropylacrylate), poly(tribromophenyl acrylate), poly(promophenyl methacrylate), etc. There is a method of forming a thin film using a spinner.

The organic crystal obtained by the production method of the present invention can be
It can be suitably used for various wiring elements, image elements, light emitting elements, etc. used in the field of electronic technology, and can be particularly suitably used as an optical waveguide using an organic nonlinear optical crystal.

Note that the method of etching an organic crystal using an active ion etching apparatus as shown in the present invention does not cause deterioration of the organic crystal, so if there is no resist pattern on the surface, etching can It can also be used to adjust the thickness of thin organic crystals.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A powder of 2-methyl-4-nitroaniline was sandwiched between two glass plates and melted at a high temperature of 140°C, and then gradually cooled from one end of the glass plate to crystallize it. Further, one of the glass plates was peeled off to obtain a 2-methyl-4-nitroaniline crystal thin film with a thickness of 2 μm on the glass plate. After forming an aluminum thin film with a thickness of 0.2 μm on the 2-methyl-4-nitroaniline crystal thin film, a quinonediazide-based positive type resist was applied, and a photomask with the desired pattern drawn on it (5 μm lines, spaces) was applied. Ultraviolet rays were irradiated through the tube (10 μm). Furthermore, the portions exposed to ultraviolet rays were dissolved and removed using a developer exclusively used for positive resists. At this time, the aluminum thin film was also removed at the same time. Etching was then performed using a reactive ion etching device. Etching conditions were CF4/02 (volume ratio) 94/6, chamber vacuum degree 0. 0 7 5
torr, 16 When the interelectrode voltage was 0.32 W/cnr, the resist was only slightly etched, and 2 methyl-
It was possible to form a fine pattern of thin film crystals of 4-nitroaniline. After etching, the entire surface is exposed to ultraviolet rays, and residual resist and aluminum are removed using a developer exclusively for positive resists to obtain a crystal thin film of 2-methyl-4-nitroaniline with a desired pattern drawn. was completed.

Example 2 After dissolving 4′ 1-nitrobenzylidene-3-acetamino-4-methoxyaniline in dimethylformamide,
By sandwiching the solution between two glass plates and gradually evaporating the solvent from the gap between the glass plates, a
' A thin film single crystal of 12-trobenzylidene-3-acetamin-4-methoxyaniline was obtained. After peeling off one glass plate, a quinonediazide-based positive type resist was applied to the upper surface of the thin film crystal using a spinner. After obtaining a desired resist pattern (line 317 μm 1 space IO μm) in the same manner as in Example 1, etching was performed using a reactive ion etching device. Etching conditions are: CF4 /02 (volume ratio) -9
0/10, chamber vacuum 0.07 5 torr
, interelectrode voltage 0. 63W/cnf, electrode cooling (25
°C), the resist was only slightly etched;
It was possible to form fine patterns of thin film crystals of acetamin-4-methoxyaniline. After etching, the entire surface is exposed to ultraviolet rays and residual resist is removed using a developer exclusively for positive resists to obtain a crystalline thin film of 4'nitrobenzylidene-3-acetamin-4methoxyaniline with a desired pattern drawn. was completed.

Example 3 As an organic crystal to be microfabricated, copper cap cyanine was deposited on a potassium chloride substrate by vacuum evaporation.
A thin film crystal with a thickness of 5000A was used. A cyclized rubber-based negative photoresist was coated on this copper lid cyanine crystal thin film, and a photomask (7 μm line, 7 μm line,
Ultraviolet rays were irradiated through a space (10 μm). Furthermore, the areas that were not exposed to ultraviolet rays were dissolved and removed using a developer exclusively used for negative photoresists. This material was placed in an etching chamber and reactive ion etching was performed (etching conditions were CF4/02 (volume ratio)
=50/50, chamber vacuum degree Q. l torr
, interelectrode voltage 0.95W/crl, electrode cooling (25°C
)) However, it was possible to form fine patterns of copper phthalocyanine. Finally, the remaining resist was removed using a special remover for negative type resist to obtain a copper phthalocyanine crystal thin film having a desired pattern.

<Effects of the Invention> By using the manufacturing method of the present invention, it becomes possible to microfabricate various organic crystals according to a desired pattern.

Furthermore, the organic crystal obtained by the production method of the present invention is
It can be suitably used in various wiring elements, image elements, light emitting elements, etc. used in the optical and electronic technology fields, and can be particularly suitably used as optical waveguides using organic nonlinear optical crystals.

[Brief explanation of drawings]

FIG. 1 shows a diagram in which the organic crystal itself is used as an optical waveguide in the present invention. FIG. 2 shows a diagram in which a material other than an organic crystal is used as an optical waveguide in the present invention. FIG. 3 shows a diagram in which a material other than an organic crystal is used as an optical waveguide in the present invention. 1: Substrate 2: Organic crystal 2': Optical waveguide of organic crystal

Claims (8)

[Claims] (1) By applying a resist sensitive to light or electron beams onto an organic crystal, exposing and developing the resist into a desired fine pattern, and then etching the organic crystal using a reactive ion etching device. A manufacturing method for obtaining an organic crystal, wherein the gas used for reactive ion etching is a mixed gas of halogenated carbon or halogenated hydrocarbon and oxygen, and the method includes cooling one of the electrodes of a reactive ion etching device. A method for producing an organic crystal, which is characterized in that the organic crystal is placed on the cooled electrode directly or via an arbitrary substrate, and then etched. (2) The method for producing an organic crystal according to claim (1), wherein the halogenated carbon is CF_4. (3) The mixed gas of halogenated carbon or halogenated hydrocarbon and oxygen used for reactive ion etching is halogenated carbon or halogenated hydrocarbon/oxygen (volume ratio) = 20/80 or more and 98/2 or less The method for producing an organic crystal according to claim 1 or 2, wherein the organic crystalline material is within the range of . (4) The method for producing an organic crystal according to claim (1), wherein the voltage applied between the electrodes of the reactive ion etching apparatus is 1 W/cm^2 or less. (5) A claim characterized in that a crystal protective layer is provided between a resist sensitive to light or electron beams and an organic crystal.
1) The method for producing the organic crystal described above. (6) The method for producing an organic crystal according to claim (1), wherein the organic crystal is a material exhibiting a nonlinear optical effect. (7) An organic crystal having a pattern of convex portions or concave portions, which is obtained by the manufacturing method according to claim (1). (8) The organic crystal body according to claim (7), wherein the optical waveguide is formed by filling the recess with a transparent material having a higher refractive index than the organic crystal body.