JPH0711424A - Production of organic pyroelectric and piezoelectric body and device therefor - Google Patents

Abstract

PURPOSE:To simultaneously produce an org. pyroelectric and piezoelectric body excellent in heat resistance and insulating property by forming a large-area polyurea film on a substrate in uniform thicknesss and quality with this device. CONSTITUTION:A positive bias voltage is impressed on a substrate 3, the substrate 3 is irradiated with an electron, monomers of a polyurea are vaporized in vacuum, a polyurea film being deposited and polymerized on the substrate 3 is polarized, and an org. pyroelectric and piezoelectric body is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a pyroelectric sensor, an infrared detector, a piezoelectric sensor such as an acceleration sensor, a flow sensor, a pressure sensor, or a transducer, etc. by utilizing its pyroelectricity or piezoelectricity. The present invention relates to a method for manufacturing an organic pyroelectric / piezoelectric material and an apparatus for manufacturing an organic pyroelectric / piezoelectric material.

[0002]

2. Description of the Related Art Conventionally, an organic pyroelectric device in which a polymer film made of polyurea subjected to polarization treatment (also called poling treatment) is interposed between opposed electrodes made of, for example, aluminum arranged in a laminated manner on a substrate. As a method of manufacturing a piezoelectric body, a lower electrode, a polyurea film, and an upper electrode are laminated in this order on a substrate in a vacuum to form a laminated body, or the lamination process is further repeated several times to laminate a multilayer structure. Form on the body.

Then, the laminate is heated from room temperature to a temperature equal to or higher than the glass transition point in the air or in a nitrogen gas atmosphere with an electric field of 100 MV / m applied between the upper and lower electrodes of the polymer film. After maintaining the temperature for a certain period of time, the temperature is lowered to room temperature to subject the polymer film to polarization treatment, or after the polymer film is formed on a substrate (which has conductivity), in the atmosphere or, for example, nitrogen. In a gas atmosphere, an electric field of, for example, 10 KV / cm is applied between the substrate and the needle, the temperature is raised from room temperature to a temperature equal to or higher than the glass transition point, the temperature is maintained for a certain time, and then the temperature is lowered to room temperature to form a polymer film. A corona poling method of performing polarization treatment is known.

Further, a polyvinylidene fluoride-based polymer material is used as a starting material for the polymer film, and the polymer material is heated to a predetermined temperature in a metal substrate or Au,
Glass substrate with Al vapor deposited (provided conductivity)
A method of evaporating the polymer raw material in a state where an electric field of, for example, 10 KV / cm is applied between the electrode and the needle-shaped or mesh-shaped electrode, and vapor-depositing it on the substrate to directly form a polymer film (electric field assist or vapor deposition in electric field). )It has been known.

[0005]

However, among the above-mentioned methods, in the case of the method in which the polarization treatment is performed after the polymer film is formed, the lower electrode, the polymer film and the upper electrode are laminated in this order on a substrate in vacuum to form a laminate. Or after further performing this lamination step a plurality of times to form a multilayer structure laminated body, and once taking out the laminated body of the electrode and the polymer film from the vacuum chamber,
Since a polymer film is subjected to polarization treatment, when manufacturing a laminated body in which a plurality of polymer films are interposed between a plurality of opposed electrodes on one substrate, the extraction electrodes are wired from all of the respective electrodes. After that, since the polymer film is subjected to polarization treatment at once, if any one of the plurality of polymer films becomes conductive during wiring of the extraction electrode, all the polymer films cannot be subjected to polarization treatment. There is a problem, and when polarization treatment is applied to multiple polymer films for each film formation in order to prevent electrical conduction to the polymer films, it takes a long time to perform polarization treatment on the polymer films, resulting in low productivity. There is a problem of being low.

In the case of the corona poling method among the above methods, unlike the above method, all the polymer films can be polarized at one time, but after the film formation, the laminate is taken out from the vacuum chamber, Since the upper electrode must be attached to the outermost polymer film by means such as vapor deposition after the polarization treatment, the dust tends to adhere to the polymer film before and after the polarization process, and the pyroelectric voltage on which the dust adheres The electric body has a problem that the dielectric breakdown of the polymer film is likely to occur, and the product yield of the organic pyroelectric voltage electric body is reduced.

[0007] Of the above methods, in the case of vapor deposition in an electric field, the raw material of the polymer film is vapor-deposited while applying a predetermined voltage to the substrate and the needle-like or net-like electrodes arranged on the front surface of the substrate. Because of the method, it is possible to perform the polarization treatment simultaneously with the formation of the polymer film on the substrate, but since the needle-shaped or mesh-shaped electrode is arranged on the front surface of the substrate, the formed polymer film is not covered with an electrode. It is easy to occur, it is not possible to form a polymer film with uniform film thickness, film quality, etc.
Due to the vacuum between the substrate and the electrode, the applied electric field cannot be made sufficiently large, so there is a problem that a large-area pyroelectric body cannot be manufactured. Moreover, it was formed on the substrate. Although the polymer film has pyroelectricity, it has low heat resistance and insulating properties, and has a problem in practicality as a pyroelectric body.

The present invention solves the above problems, heat resistance,
A method for producing an organic pyroelectric / piezoelectric material, which has a pyroelectric property excellent in insulation and can form a large-area polyurea film having a uniform film thickness and a film quality very easily on a substrate, and It is an object of the present invention to provide a manufacturing device thereof.

[0009]

The method of manufacturing an organic pyroelectric body according to the present invention comprises an organic polyurea film formed by evaporating a raw material monomer of a polyurea resin in a vacuum and subjecting this to vapor deposition polymerization on a substrate. In the method for manufacturing a pyroelectric / piezoelectric material, a positive bias voltage is applied to the substrate, and the raw material monomer is vapor-deposited and polymerized on the substrate while irradiating the substrate with electrons from the electron source. To do.

The apparatus for manufacturing an organic pyroelectric body comprises an evaporation source for evaporating a raw material monomer of a polyurea resin in a vacuum processing chamber, and an organic polyurea film formed by vapor deposition polymerization of the raw material monomer vaporized from the evaporation source. In an organic pyroelectric / piezoelectric manufacturing apparatus in which a substrate on which a thin film of a pyroelectric / piezoelectric material is formed is arranged to face each other, an electron supply source for emitting and irradiating electrons to the substrate is provided in a vacuum processing chamber. It is characterized by being provided.

[0011]

When the raw material monomer of the polyurea resin is evaporated in vacuum, the vapor of the raw material monomer is vapor-deposited on the substrate, and the polyurea film is formed on the substrate by polymerization. At that time, when there is no electric field, the diurea (urea bond) in the polyurea film formed on the substrate is oriented in an arbitrary direction, so that the formed polyurea film needs to be polarized.

In the present invention, since an electric field exists during the vapor deposition polymerization of the raw material monomer of polyurea on the substrate, the electrons emitted from the electron source are irradiated toward the substrate. If a polyurea film is formed on the substrate in this state, electrons are charged on the film surface because polyurea is a dielectric, and an electric field is generated between the charged electrons and the substrate, that is, the film thickness of polyurea. As a result, the electric field causes the polyurea to have a dipole orientation and is polarized, and as a result, the formed polyurea film is pyroelectric.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, an apparatus for manufacturing an organic pyroelectric / piezoelectric material according to the present invention will be described.

FIG. 1 shows an example of an apparatus for manufacturing an organic pyroelectric / piezoelectric material according to the present invention. In the figure, 1 indicates a vacuum processing chamber.
A substrate holder for connecting the inside of the vacuum processing chamber 1 to an external vacuum pump or other vacuum exhaust system 2 and holding a substrate 3 on which an evaporation film of an organic pyroelectric / piezoelectric material is to be formed above the vacuum processing chamber 1. 4 was placed.

The substrate 3 is provided below the vacuum processing chamber 1.
Of a glass or copper container for evaporating one raw material monomer A (for example, diamine) and the other raw material monomer B (for example, diisocyanate) of the polyurea film of the pyroelectric / piezoelectric material facing each other. Sources 5 and 6 are arranged, and heaters 7 and 8 are arranged near the evaporation sources 5 and 6, respectively.
The raw material monomers A and B can be heated to a predetermined temperature.

In the apparatus shown in FIG. 1, the inside of the substrate holder 4 is connected to a circulation pump 10 via a circulation pipe 9, and a liquid having a constant temperature (for example, constant temperature water having a temperature of 25 ° C. or A coolant such as ethyl alcohol) is circulated in the substrate holder 4 and the substrate holder 4
The substrate 3 held at the temperature can be maintained at a predetermined temperature.

Further, the substrate holder 4 is connected to the DC power source 11 so that a positive bias voltage can be applied to the substrate 3 held by the substrate holder 4.

Further, in the vicinity of above the evaporation sources 5 and 6,
Raw material monomer A, which is heated by each evaporation source 5 and 6 to evaporate,
A filament-shaped electron source 12 for emitting electrons such as tungsten and platinum is arranged at a position that does not affect the evaporation of the vapor of B toward the substrate 3, and the electron source 1
2 was connected to the DC power supply 11 via a wiring 13, and an ammeter 14 and a voltmeter 15 were arranged in the wiring 13.

Then, the DC power supply 11 is used to connect 100 to the substrate 3.
While applying a positive bias voltage of about V, the electron source 12 irradiates the substrate 3 with electrons to generate a direct current electric field between the substrate 3 and the electron source 12, and the evaporation source on the substrate 3 is generated. In order to obtain an organic pyroelectric / piezoelectric material consisting of a polyurea film in which dipoles are oriented in a certain direction by performing polarization treatment during vapor deposition and polymerization of raw material monomers A and B that are heated and vaporized by 5 and 6 did. In this case, the DC electric field applied between the substrate 3 and the electron supply source 12 is set according to the film thickness formed on the substrate 3, but for the film thickness of 1 μm, the DC power supply 11 is used.
Voltage is about 50 to 100 V and the ammeter 14 is set to 1
The electric field applied was controlled by the voltmeter 15 so as to show about ˜several μA / cm ² (surface area of the substrate).

In the figure, 16 is a shutter interposed between the substrate 3 and both evaporation sources 5 and 6, 17 is a partition plate provided between both evaporation sources 5 and 6, and 18 is a ground.

Next, a specific embodiment of the method for producing an organic pyroelectric / piezoelectric material of the method of the present invention will be described along with the comparison using the illustrated apparatus.

Example 1 In this example, the substrate 3 is a polyimide film of 50 mm × 40 mm × thickness of 25 μm (substrate area 20 cm ² ) on which a 0.2 μm thick aluminum lower electrode is deposited. Is closely attached to the copper substrate holder 4,
The anode side of the DC power supply 11 is connected to the aluminum lower electrode of the substrate 3, the cathode side of the DC power supply 11 is connected to the electron supply source 12, and the distance between the substrate 3 and the electron supply source 12 is set to 5 cm. The substrate 3 side was positive between 12 and a current of ² μA / cm ² was applied per unit area of the substrate to apply an electric field of about 100 V to a film thickness of 1 μm.

First, 4,4'-diaminodiphenylmethane (hereinafter referred to as raw material monomer A) is used as one raw material monomer A of the polyurea film in the evaporation source 5 in the vacuum processing chamber 1.
The evaporation source 6 was filled with 4,4′-diisocyanatodiphenylmethane (hereinafter referred to as the raw material monomer B) as the other raw material monomer B of the polyurea film, and the pressure in the vacuum processing chamber 1 was maintained with the shutter 16 closed. Was set to 2 × 10 ⁻³ Pa by the vacuum exhaust system 2.

Next, the raw material monomer A is heated by the evaporation source 5 to 110
To ± 0.2 ° C, and the raw material monomer B is 71 ± by the evaporation source 6
Each was heated to 0.2 ° C.

Further, the circulation pump 10 is provided in the substrate holder 4.
A warm coolant composed of more water was circulated through the circulation pipe 9 to maintain the substrate 3 at a temperature of 50 ° C.

Next, when the raw material monomers A and B reach a predetermined temperature, the shutter 16 is opened to evaporate the raw material monomers A and B at a deposition rate of 0.5 to 1 Å / sec and deposit them on the substrate 3. While depositing, the deposit is polymerized while applying the electric field to a thickness of 500.
A 0Å polyurea film was formed.

The raw material monomers A and B are adjusted to 1: by adjusting the evaporation amount so that a polyurea film is stoichiometrically formed.
Evaporation was carried out at a molar ratio of 1. The pressure in the vacuum processing chamber 1 during the evaporation of the raw material monomers A and B is 1 × 1.
It was set to 0 ⁻³ Pa.

After forming a polyurea film on the substrate 3, aluminum is vapor-deposited (thickness: 0.
2 μm) and used as the upper electrode.

Then, after the substrate with the lower electrode on which the polyurea film and the upper electrode are formed is taken out from the vacuum processing chamber 1, the lead wires are pulled out from the upper electrode and the lower electrode, respectively, and the pyroelectric coefficient and the piezoelectric are obtained by a conventional method. The rate was examined and the results are shown in Table 1.

Comparative Example 1 As in Example 1 except that the raw material monomers A and B were vapor-deposited, a positive bias voltage was not applied to the substrate 3 during the polymerization, and no electron was emitted from the electron source 12. A polyurea film was formed on the substrate 3 by the same method, and an upper electrode was formed on the polyurea film.

Then, the substrate with the lower electrode on which the polyurea film (without applying bias voltage and electron irradiation) and the upper electrode is formed is taken out from the vacuum processing chamber 1, and then, between the upper and lower electrodes, that is, in the nitrogen atmosphere. The polyurea film was heated to a temperature of 180 ° C. with a direct current of 50 V applied, maintained at the temperature for 10 minutes, then stopped applying and heating, and the polyurea film was gradually cooled from 180 ° C. to room temperature. The polyurea film was subjected to poling treatment.

After the poling treatment, lead wires were respectively drawn from the upper electrode and the lower electrode, and the pyroelectric and piezoelectric constants were examined by a conventional method. The results are shown in Table 1.

Comparative Example 2 The same as Example 1 except that the source monomers A and B were vapor-deposited, a positive bias voltage was not applied to the substrate 3 during the polymerization, and no electron was emitted from the electron source 12. A polyurea film was formed on the substrate 3 by the same method.

Then, after taking out the substrate with the lower electrode on which the polyurea film (without applying a bias voltage and without irradiating electrons) was taken out from the vacuum processing chamber 1, an interval of 2 cm was provided between the needle electrodes connected to the power source. The polyurea film side formed on the substrate is made to face each other, the power source is connected to the lower electrode of the substrate, and a voltage of an electric field of 10 KV is applied between the needle electrode and the lower electrode in the atmosphere. Heat to 180 ° C and bring the temperature to 1
After maintaining for 0 minutes, application and heating were stopped, the temperature of the polyurea film was gradually cooled from 180 ° C. to room temperature, and the polyurea film was subjected to corona poling treatment.

After the corona poling treatment, aluminum was vapor-deposited (thickness: 0.2 μm) on the polyurea film by vacuum vapor deposition to form an upper electrode.

Then, lead wires were respectively drawn from the upper electrode and the lower electrode, and the pyroelectric coefficient and piezoelectric coefficient were examined by a conventional method. The results are shown in Table 1.

Comparative Example 3 The same as Example 1 except that the deposition of the raw material monomers A and B, the application of a positive bias voltage to the substrate 3 during the polymerization, and the irradiation of electrons from the electron supply source 12 were not performed at all. A polyurea film was formed on the substrate 3 by the same method, and an upper electrode was formed on the polyurea film.

Then, after removing the substrate with the lower electrode on which the polyurea film (without applying bias voltage and electron irradiation) and the upper electrode is taken out from the vacuum processing chamber 1, the lead wires are respectively fed from the upper electrode and the lower electrode. Was extracted and the pyroelectric and piezoelectric constants were investigated by a conventional method, and the results are shown in Table 1.

[0040]

[Table 1]

As is clear from Table 1, the pyroelectric and piezoelectric constants of Example 1 were 1 for the comparative example 1 after the film-forming poling treatment and 2 for the comparative example 2 after the film-forming corona poling treatment. The values of about 70% of the pyroelectric coefficient and the piezoelectric coefficient are shown, which means that the polyurea film during film formation can be reliably subjected to poling treatment, and the poling treatment to the polyurea film after film formation, That is, it was confirmed that the polarization treatment was not required.

The organic pyroelectric / piezoelectric material of Example 1 has 18
It was confirmed that stable characteristics were obtained up to 0 ° C. and that there was no problem in practicality.

As described above, since the positive bias voltage is applied to the substrate, an electric field is generated in the vicinity of the substrate, the electrons emitted from the electron supply source are irradiated to the substrate, and polyurea is generated in this state. When polyurea is formed, electrons are charged on the surface of polyurea because polyurea is a dielectric. In fact, as the polyurea film grows thicker, the initial current of 1 μA / cm ² approaches 0, and finally the current stops flowing.
An electric field is applied between the charged electrons and the substrate, that is, the film thickness of the polyurea, and the electric field polarizes the polyurea. For example, when 100 V is applied between the electron supply source and the substrate, when the final polyurea film is 1 μm, 100 V / 1 μm = 100 M
An electric field of V / m will be applied. It is easy to strengthen this electric field.

[0044]

As described above, according to the method for producing an organic pyroelectric / piezoelectric material of the present invention, a positive bias voltage is applied to the substrate by vapor deposition and polymerization of the raw material monomer of polyurea on the substrate,
Since the process is performed while irradiating the substrate with electrons, the polyurea film formed at the same time as the vapor deposition polymerization has the dipole orientation, which has excellent heat resistance and insulation and pyroelectricity. There is an effect that an organic pyroelectric / piezoelectric body composed of a large-area polyurea film having a uniform film thickness and a film quality can be easily and efficiently produced without causing a baldness due to a striped or reticulated electrode.

Further, according to the apparatus for manufacturing an organic pyroelectric / piezoelectric material of the present invention, since the electron source for irradiating the substrate with electrons is arranged in the vacuum processing chamber, the evaporation source and the substrate as in the conventional apparatus are disposed. Since there is no needle-shaped or mesh-shaped electrode between the and, it has pyroelectricity that is excellent in heat resistance and insulation without causing electrode shading, and has a uniform film thickness and a large-area organic focus. It is effective to provide a manufacturing apparatus that can easily and efficiently manufacture an electric / piezoelectric material.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of an apparatus for manufacturing an organic pyroelectric / piezoelectric material of the present invention.

[Explanation of symbols]

1 vacuum processing chamber, 2 vacuum exhaust system, 3
Substrate, 4 substrate holder, 5, 6 evaporation source,
11 power source, 12 electron source, A, B raw material monomer.

Claims (2)

[Claims] 1. A method for producing an organic pyroelectric / piezoelectric material comprising a polyurea film by evaporating a raw material monomer of a polyurea resin in a vacuum and vapor-depositing and polymerizing the monomer on a substrate to apply a positive bias voltage to the substrate. In addition, the method for producing an organic pyroelectric / piezoelectric material is characterized in that vapor deposition polymerization of the raw material monomer is performed on the substrate while irradiating the substrate with electrons from the electron supply source. 2. An evaporation source for evaporating a raw material monomer of a polyurea resin in a vacuum processing chamber, and an organic pyroelectric / piezoelectric thin film made of a polyurea film is formed by vapor deposition polymerization of the raw material monomer vaporized from the evaporation source. In an organic pyroelectric / piezoelectric manufacturing apparatus in which a substrate and a substrate are opposed to each other, an electron supply source for emitting and irradiating electrons to the substrate is provided in a vacuum processing chamber. -Piezoelectric manufacturing equipment.