KR20030033270A - The surface reforming method of a piezoelectric or pyroelectric material using an ion-beam - Google Patents

Abstract

PURPOSE: A surface reforming method of piezoelectric or pyroelectric material by using an ion beam is provided to improve the durability, and to extend the life span by improving adhesive force between electrodes with reforming the surface of piezoelectric or pyroelectric polymer film. CONSTITUTION: Vacuum is formed in a vacuum tub(1) by a vacuum pump(5), and piezoelectric or pyroelectric polymer material is placed on an ion gun(3) in the vacuum tub. An ion beam is generated from the ion gun with ion injection energy, and irradiated to the surface of piezoelectric or pyroelectric polymer material. Reactive gas is injected through a gas injection pipe of the vacuum tub, and the hydrophilic group is generated in the surface of the piezoelectric or pyroelectric polymer. The endurance of the piezoelectric or pyroelectric element is improved by increasing adhesive force with reforming the surface of the piezoelectric or pyroelectric polymer through the ion beam.

Description

Surface reforming method of a piezoelectric or pyroelectric material using an ion-beam

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of surface modification of piezoelectric or pyroelectric polymer materials using ion beams, and more particularly to the surface of piezoelectric or pyroelectric polymer materials for improving adhesion and durability by surface treatment of piezoelectric or pyroelectric polymer films by ion assist reaction method. It is about a reforming method.

Conventionally, piezoelectric and pyroelectric material materials including ceramic materials such as quartz crystals or barium titanate have been mainly used, but recently, polyvinyliden fluoride (PVDF); Many devices have been researched and commercialized using piezoelectric and pyroelectric polymer materials, including PVDF.

The piezoelectric and pyroelectric polymer materials are more flexible and lighter than conventional materials. In addition, the piezoelectric and pyroelectric polymer materials have a wide vibration range, and thus, the replacement of existing piezoelectric and pyroelectric devices and the development of new devices using the same are being actively attempted. It has been a long time since film-type speakers using PVDF were developed.

However, piezoelectric and pyroelectric polymer materials that are currently in practical use are not easily adhered to the electrode materials necessary for device implementation due to low surface energy, which makes it impossible to implement the device or to limit the lifetime of the manufactured device. there was.

The present invention has been made to solve the above problems, an object of the present invention is to improve the adhesion by surface treatment of the piezoelectric and pyroelectric polymer material by ion assist reaction method, thereby improving the durability of the piezoelectric or pyroelectric element It is to provide a surface modification method for fabrication and fabrication of a new concept device.

1 is a longitudinal sectional view of an ion beam surface treatment apparatus for performing a method for surface modification of piezoelectric or pyroelectric polymer materials using an ion beam according to the present invention;

Figure 2 is a graph showing the change in contact angle between the surface treated PVDF and water by the surface modification method according to the present invention.

Figure 3 is a graph showing the XPS C1s core level spectra analysis of the surface treated PVDF surface modification method according to the present invention.

Figure 4 is a graph showing the XPS O1s core level spectra analysis of the surface treated PVDF surface modification method according to the present invention.

5 is a graph showing the surface energy change of the surface treated PVDF by the surface modification method according to the present invention.

Figure 6 is a graph showing the boiling test results of the platinum electrode deposited on the PVDF, (a) is a state in which the PVDF is not surface-treated, (b) to (d) is 5 × 10 ¹⁴ Ar ⁺ / cm ² , 1 × 10 ¹⁵ Ar ⁺ / cm ² , 1 × 10 ¹⁷ Ar ⁺ / cm ² The graph showing the results of the surface treatment state with the injection amount.

7 is a graph showing the sheet resistance and transmittance change according to the thickness of the ITO thin film deposited on the polymer substrate according to the application of the present invention.

<Description of the symbols for the main parts of the drawings>

1: vacuum chamber 2: sample (piezoelectric or pyroelectric polymer material)

3: ion gun 4: gas injection pipe

5: vacuum pump 6: ion beam

In order to achieve the above object, in the method of surface modification of piezoelectric or pyroelectric materials used in the manufacture of piezoelectric or pyroelectric elements, the piezoelectric or pyroelectric polymer material located in a vacuum chamber is placed in a vacuum chamber, and then ion The piezoelectric or pyroelectric body is formed by generating a predetermined amount of ion beam from a gun with a predetermined amount of ion beam, and injecting a predetermined amount of reactive gas through the gas injection tube of the vacuum chamber while irradiating the surface of the piezoelectric or pyroelectric polymer material. It is characterized by forming a hydrophilic functional group on the surface of a high molecular material.

In addition, the reactive gas is characterized in that any one of oxygen, air, ammonia, hydrogen, carbon monoxide, carbon dioxide, nitrogen, nitrous oxide, hydrocarbons.

And, the ion implantation energy of the ion beam generated in the ion gun is characterized in that the range of 100 to 10000 eV,

The ion implantation amount of the ion beam irradiated on the surface of the piezoelectric or pyroelectric polymer material is 1 × 10 ¹² to 1 × 10 ²⁰ ions / cm ² .

In addition, the injection amount of the reactive gas is characterized in that 1 to 500 sccm,

The degree of vacuum in the reactor is characterized in that 1 × 10 ^-1 torr to 1 × 10 ^-6 torr.

The piezoelectric or pyroelectric polymer material may be polyvinylidene fluoride, vinylidene fluoride trifluoroethylene, odd nylon, vinylidene cyanide, poly (vinylidene cyanine-vinylacetate), poly (methyl methacrylate- Piezoelectric or pyroelectric polymers having a piezoelectric or pyroelectric property composed of polytributyllane, polytrifluethylene and poly (vinyl fluoride) and copolymer materials thereof, or piezoceramic composed of PZT, PbTiO ₃ , and Ca-PbTiO ₃ . It is characterized in that the composite material containing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention uses an ion assist reaction method for surface modification of piezoelectric or pyroelectric polymer materials.

1 is a longitudinal sectional view of an ion beam surface treatment apparatus for carrying out a method for surface modification of a piezoelectric or pyroelectric polymer material using an ion beam according to the present invention. As shown in FIG. 1, after placing the sample 2 in the upper part of the ion gun 3 in the vacuum chamber 1 holding the vacuum by the vacuum pump 5, the ion gun 3 generates an ion beam. This is irradiated to the sample (2). Here, the degree of vacuum in the vacuum chamber is preferably 1 × 10 ^-1 torr to 1 × 10 ^-6 torr, and the ion implantation energy of the ion beam is preferably irradiated within the range of 10 to 10000 eV. In addition, it is preferable that the ion implantation amount of the ion beam irradiated to the surface of the said sample 2 is 1 * 10 <^12> -1 * 10 <^20> ion / cm <^2> .

The sample (2) is a piezoelectric or pyroelectric polymer material, the piezoelectric or pyroelectric polymer material is PVDF, vinylidene fluoride-trifluoroethylene (VDF-TrFE), odd nylon (nylon 7 , nylon 11)), vinylidene cyanide (VDCN: vinylidene cyanide), poly (vinylidene cyanine-vinylacetate) (P (VDCN-VAcpoly (vinylidene cyanine-vinylacetate)), poly (methyl methacrylate-poly Piezoelectrics such as tributyllane (P (TBTM-MMA: Poly (methyl methacrylate-polytributyline methacrylate))), polytrifluorethylene (PtrFE), poly (vinyl fluoride) (PVF: poly (vinyl fluoride)) Or a composite material containing a piezoelectric polymer and a copolymer thereof or piezoceramic such as PZT, PbTiO ₃ , Ca-PbTiO _3, or the like.

At the same time, a reactive gas is injected through a gas injection pipe 4 outside the vacuum chamber 1 to generate ions, which are oxygen, air, ammonia, hydrogen, carbon monoxide, carbon dioxide, nitrogen, nitrous oxide, Any of the hydrocarbons can be used. In addition, instead of the reactive gas, a fluorinated gas such as helium, argon, nitrogen, neon, xenon, krypton or the like may be injected. Here, the injection amount of the reactive gas is preferably 1 to 500 sccm.

Looking at the ion-assisted reaction method, by irradiating a low energy ion beam of 0.1 keV to 10 keV on the surface of the polymer and blowing a reactive gas around the polymer to create a new hydrophilic functional group on the surface of the polymer. When the electrode material is deposited on the piezoelectric and pyroelectric polymers by the hydrophilic functional groups generated as described above, physical and chemical bonding is performed with the electrode material to be deposited, thereby obtaining excellent adhesion even in precious metals such as Pt and Au.

Figure 2 is a graph showing the change in contact angle between the surface treated PVDF and water by the surface modification method according to the present invention, PVDF according to the amount of ion irradiation in the result of the surface treatment using PVDF, a kind of piezoelectric polymer using the ion assisted reaction method This graph shows the change of contact angle with water.

Due to its hydrophobic nature, PVDF has a high value of 75 ^° before surface treatment using ion assisted reaction. However, it is shown to be lowered to 31 ^o after surface treatment with an ion irradiation amount of 1 × 10 ¹⁵ ions / cm ^{2 at} the same time as the surface is blown with the reactive gas O ₂ .

The result of decreasing the contact angle after the surface treatment is due to the hydrophilic action newly formed on the PVDF surface by the ion assist reaction method.

Figure 3 is a graph showing the results of XPS C1s core level spectra analysis of the surface treated PVDF by the surface modification method according to the present invention, a graph showing the comparison of XPS C1s core level spectra before and after the surface treatment.

The formation of hydrophilic functional groups on the PVDF surface can be confirmed by comparing the chemical structure change of the PVDF surface before and after the surface treatment using XPS (X-ray Photoelectron Spectroscopy) analysis.

Only inherent peaks of -CH _2- (286.2 eV) and -CF _2- (290.8 eV) are observed in the C1s core level spectra of PVDF before the surface treatment. However, in case of PVDF surface-treated with reactive gas using ion assisted reaction, the -CF ₂ -peak is drastically reduced while -CO- (286.1eV),-(C = O) -O- (289.0eV) Peaks can be observed to emerge or increase. The bonds are hydrophilic, so that the contact angle may be reduced as shown in FIG. 2.

Figure 4 is a graph showing the XPS O1s core level spectra analysis of the surface treated PVDF by the surface modification method according to the present invention. As shown, in the case of the O1s core level spectra, oxygen is hardly present in the surface-treated PVDF, but the binding of oxygen increased from the PVDF modified with an ion irradiation amount of 5 × 10 ¹⁴ ions / cm ² . This is in good agreement with the results of FIG. 3.

Figure 5 is a graph showing the surface energy change of the surface treated PVDF by the surface modification method according to the present invention, showing the surface energy change of the treated PVDF according to the ion irradiation amount.

The surface energy of the PVDF is measured by the contact angle between two polar solutions, water and formamide, and calculates the dispersion force and the polar force, and then calculates the calculated values. Can be summed to calculate surface energy values.

As shown in FIG. 5, the amount of 36 ergs / cm ² before the surface treatment increased to 64 ergs / cm ² when the surface treatments were performed with 1 × 10 ¹⁵ ions / cm ² ion dosage. Here, the increase in surface energy is due to the formation of the hydrophilic functional groups described above, and these hydrophilic functional groups greatly increase adhesion by mutual physical and chemical bonding with the electrode material deposited on the PVDF.

Therefore, various electrode materials (precious metals: Pt, Au, Ag, Al, Ni, Ti, Cu, etc.) currently used, as well as various electrode materials limited in use in device fabrication due to weak adhesiveness with electrodes until now. Au, Ag, etc., conductive oxides: ITO, SnO ₂ , ZnO, CeO _2, etc. and their doped conductive oxides, doped polyacetylene (PA), polyethylene dioxythiophene polysulfone sulfidede (PEDT: Polyethylene dioxythiophene polystyrene) sulphonate), polyaniline (PAN: Polyaniline), poly ( p- phenylene) (PPV: Poly ( p- phenylene)), poly (p-phenylenevinylene) (PPP: Poly ( p- phenylenevinylene)), polypinol (PPy: Polypyrrole), polythiophene (PT) and derivatives thereof, conductive polymers (π-conjugated polymers) and their derivatives and doped organic molecules, have been made available for device fabrication.

Figure 6 is a graph showing the boiling test results of the platinum electrode deposited on the PVDF, (a) is a state in which the PVDF is not surface-treated, (b) to (d) is 5 × 10 ¹⁴ Ar ^It is the result which showed the surface-treated state by the injection amount of ⁺ / cm <^2> , 1 * 10 <^15> Ar ⁺ / cm <^2> , 1 * 10 <^17> Ar ⁺ / cm <^2> . Here, Ar ⁺ ions have been used for the surface treatment, but other ions of the foil can also be used.

As shown in (a) of FIG. 6, it can be seen that the Pt thin film deposited on the surface-treated PVDF is buckling over a large area. However, as shown in FIGS. 6 (b) to (d) surface treated with Ar ⁺ ions, the deposited platinum thin film was significantly reduced as shown in FIG. 6, and after the ion irradiation amount of 1 × 10 ¹⁵ ions / cm ² , It can be seen that cracks have progressed in the thin film instead of the phenomenon. The occurrence of such cracks is because the stress generated by the difference in coefficient of thermal expansion when the adhesion at the interface is excellent is solved by the formation of cracks instead of peeling the thin film, it can be seen that the bonding force between the PVDF and the platinum electrode is improved.

As an application of the present invention, a circular PVDF film speaker using a transparent conductive oxide ITO thin film as an electrode may be mentioned.

In general, an indium tin oxide (ITO) thin film, which is a transparent conductive oxide, is less ductile than a metal electrode, and thus, lacks resistance to micro-vibration generated when a piezoelectric element is operated. Low resistance is required to do this.

In addition, in the case of PVDF, it is impossible to heat to a high temperature because the melting point is low, so it is difficult to obtain a low resistance comparable to that of a metal electrode. In the case of using the conventional sputtering deposition method, PVDF and plasma are directly contacted. As a result, the surface treatment effect of PVDF is drastically lowered due to the collision of high energy particles.

Therefore, in the present invention, ion beam sputtering is used instead of the conventional sputtering method as the deposition method of the ITO electrode. The ion beam sputtering separates the plasma from the substrate, thereby minimizing damage to the substrate and depositing a thin film having excellent characteristics at low temperature. have.

Using the ion beam sputtering method according to the present invention, the sheet resistance and the transmittance change at 550 nm according to the thickness of the ITO thin film deposited at 50 ° C., as shown in FIG. An ITO thin film having a sheet resistance and a high transmittance of 82% can be obtained, and the sheet resistance value is reduced to 10 times or less as compared to the case where Pt is deposited at 500 Å, thereby serving as an electrode.

Therefore, the ITO or transparent conductive polymer and the doped organic monomolecule may be used as an electrode material as a speaker of a TV CRT, a computer monitor, a projection TV, a PDA, a mobile phone, and the like.

The present invention can be applied to the manufacture of a speaker integrated display device (monitor) and the manufacture of a micro pump used in an inkjet printer head using a polymer piezoelectric material, and can be applied to various fields.

In addition, piezoelectric and pyroelectric polymer devices surface-treated by ion-assisted reaction method to improve adhesion to electrodes have a microphone, piezoelectric transducer, which converts mechanical force and thermal energy into electrical signals using piezoelectric and pyroelectric properties. It can be used for motion sensor, infrared image sensor, light sensor, hydrogen sensor, ultrasonic vibration device manufacturing, and the like.

Although the present invention has been described in detail above, those of ordinary skill in the art to which the present invention pertains may variously modify the present invention without departing from the spirit and scope of the present invention as defined in the appended claims. It is apparent that the present invention may be modified or modified. Therefore, a simple change according to an embodiment of the present invention will not be possible without departing from the technology of the present invention.

According to the surface modification method according to the present invention described above, by modifying the surface of the piezoelectric or pyroelectric polymer film having a piezoelectric or pyroelectric properties to improve the adhesion between the electrodes in the production of piezoelectric or pyroelectric elements, from which piezoelectric or excellent durability It is possible to manufacture a pyroelectric element and a new concept of the element, and additionally, adhesive strength may be improved to extend the life of the piezoelectric or pyroelectric element.

In addition, various electrode materials, which have been limited in use until now, have an effect that can be used in device fabrication.

Claims (8)

In the method of surface modification of piezoelectric or pyroelectric materials used in the production of piezoelectric or pyroelectric elements, After placing the piezoelectric or pyroelectric polymer material located in the vacuum chamber in the vacuum chamber, a predetermined amount of ion beam is generated from the ion gun with a predetermined ion implantation energy, and the vacuum is irradiated onto the surface of the piezoelectric or pyroelectric polymer material. A method of modifying the surface of a piezoelectric or pyroelectric polymer material using an ion beam, characterized by forming a hydrophilic functional group on the surface of the piezoelectric or pyroelectric polymer material by injecting a predetermined amount of reactive gas through a gas injection tube of a bath. The method of claim 1, wherein the reactive gas is any one of oxygen, air, ammonia, hydrogen, carbon monoxide, carbon dioxide, nitrous oxide, and hydrocarbons. The method of claim 1, wherein the ion implantation energy of the ion beam generated by the ion gun is in the range of 100 to 10000 eV. The method of claim 1, wherein the ion implantation amount of the ion beam irradiated on the surface of the piezoelectric or pyroelectric polymer material is 1 × 10 ¹² to 1 × 10 ²⁰ ions / cm ² of the piezoelectric or pyroelectric polymer material using an ion beam Surface modification method. The method of claim 1, wherein the injection amount of the reactive gas is in the range of 1 to 500 sccm. The method for surface modification of a piezoelectric or pyroelectric polymer material using an ion beam according to claim 1, wherein the degree of vacuum in the reactor is 1 × 10 ⁻¹ torr to 1 × 10 ⁻⁶ torr. The method of claim 1, wherein the piezoelectric or pyroelectric polymer material is polyvinylidene fluoride, vinylidene fluoride trifluoroethylene, odd nylon, vinylidene cyanide, poly (vinylidene cyanine-vinylacetate), poly (methyl Piezoelectric or pyroelectric or piezoelectric polymers having a piezoelectric or pyroelectric property composed of methacrylate-polytributyllane), polytrifluoroethylene, and poly (vinyl fluoride) and copolymer materials thereof. Method of surface modification of the whole polymeric material. The method of claim 1, wherein the piezoelectric or pyroelectric polymer material is a composite material including a piezoelectric ceramic composed of PZT, PbTiO ₃ , and Ca-PbTiO ₃ . .