JP2020165887A - Piezoelectric laminated sheet, manufacturing method therefor, piezoelectric sensor, and manufacturing method therefor - Google Patents

Abstract

To provide a piezoelectric laminated sheet which can be used to easily produce piezoelectric sensor elements, a method of manufacturing the same, a piezoelectric sensor element produced using such piezoelectric laminated sheet, and a method of manufacturing the same.SOLUTION: A piezoelectric laminated sheet provided herein is a piezoelectric laminate comprising at least a first conductive layer, a piezoelectric layer abutting the first conductive layer, an adhesive layer, a peeling layer, and a second conductive layer, where the peeling layer and the second conductive layer can be separated from the adhesive layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a piezoelectric laminated sheet, a piezoelectric sensor using the same, and a method for manufacturing the same.

Organic piezoelectric materials have a low dielectric constant and a high piezoelectric constant, can be converted into ink, can be formed by coating / printing, and have chemical stability and flexibility. Due to its characteristics, its application to flexible pressure sensors, vibration sensors, energy harvesting elements, actuators, etc. is being studied.

As an organic piezoelectric material, polyvinylidene (PVDF), which is a fluorine-based polymer semiconductor material, is well known, and polyfluorovinylidene-trifluoroethylene copolymer weight obtained by copolymerizing trifluoroethylene (TrFE) with this. Coalescence (P (VDF-TrFE)) is particularly well known. In addition, there are polylactic acid and polyamino acids.

By sandwiching these organic piezoelectric materials as films and thin films (organic piezoelectric layers) between electrodes, studies are underway to apply them to sensors (organic piezoelectric elements) that react to pressure, vibration, heat, infrared rays, etc. ( Non-patent document 1). There is also a report that a highly sensitive sensor element can be manufactured by connecting such an organic piezoelectric element to a circuit such as a thin film transistor (Non-Patent Document 2). Further, Patent Document 1 discloses a pressure-sensitive element having an organic piezoelectric layer.

JP-A-2017-219336

S. Hannah, A.M. Davidson, I. et al. Gresk, D.M. Uttamchandani, R.M. Dahiya, "Multifectional Sensor base on organic field-effect transistor and ferroelectric poly (vinylideene fluoride trifluoroelectric -1, Y. Tsuji, H. et al. Sakai, L. et al. Feng, X.I. Guo, H. et al. Murata, "Dual-gate low-voltage organistic transistor for puressure sensing", Applied Physics Express, 10,021601 (2017).

In order to obtain the piezoelectric effect of the organic piezoelectric material, it is necessary that the dipoles in the molecule are oriented in the same direction and spontaneous polarization is generated. Therefore, a process called polling process (polarization process) is performed to align the directions of the dipoles.

In order to generate spontaneous polarization by such polling processing, it is necessary to apply a high electric field of several kV / mm. Therefore, if the polling process is performed after combining the organic piezoelectric material as a sensor with the control circuit or the thin film transistor, the circuit may be destroyed.

The present invention has been made in view of these points, and provides a piezoelectric laminated sheet capable of easily producing a piezoelectric sensor element and a method for manufacturing the same, and a sensor element using the piezoelectric laminated sheet and the present invention. It is an object of the present invention to provide a manufacturing method.

One aspect of the present invention for solving the above problems is a first conductive layer, a piezoelectric layer in contact with the first conductive layer, an adhesive layer, a release layer, and a second conductive layer. The peeling layer and the second conductive layer are piezoelectric laminated sheets that can be peeled from the adhesive layer.

Further, the adhesive layer may have conductivity.

Further, the piezoelectric layer may have spontaneous polarization.

Further, the piezoelectric layer may be an organic piezoelectric material.

Further, the piezoelectric layer may be an organic electret material.

Further, another aspect of the present invention includes a step of forming a laminate in which the first conductive layer, the piezoelectric layer, the adhesive layer, the peeling layer and the second conductive layer are laminated in this order, and the first conductive layer. This is a method for manufacturing a piezoelectric laminated sheet, which comprises a step of applying an electric field between the two conductive layers and performing a polarization treatment of the piezoelectric layer.

Another aspect of the present invention is the piezoelectric sensor, which is in contact with the first conductive layer, the piezoelectric layer in contact with the first conductive layer, the adhesive layer, and the adhesive layer. It may have at least a bonded sensor electrode layer.

Further, the adhesive layer of the above-mentioned piezoelectric sensor may have conductivity.

Further, another aspect of the present invention is a step of peeling the peeling layer and the second conductive layer of the manufactured piezoelectric laminated sheet from the adhesive layer, and the piezoelectric laminated sheet from which the second conductive layer is peeled is used as a sensor substrate. It is a method of manufacturing a piezoelectric sensor including a step of attaching to an electrode.

According to the present invention, a piezoelectric laminated sheet to which a piezoelectric sensor element can be easily manufactured by attaching a piezoelectric laminated sheet to which piezoelectricity has been imparted in advance to a sensor circuit substrate by an adhesive layer, a method for manufacturing the piezoelectric laminated sheet, and piezoelectricity. It is possible to provide a sensor element using a body laminated sheet and a method for manufacturing the same.

Schematic cross-sectional view of the piezoelectric laminated sheet according to the first embodiment of the present invention. Schematic cross-sectional view of the piezoelectric laminated sheet according to the second embodiment of the present invention. Schematic cross-sectional view of the piezoelectric laminated sheet according to the third embodiment of the present invention. Schematic cross-sectional view of the piezoelectric laminated sheet according to the fourth embodiment of the present invention. Schematic cross-sectional view of a piezoelectric sensor using the thin film transistor of the present invention. Schematic cross-sectional view of a piezoelectric sensor using the thin film transistor of the present invention. Schematic cross-sectional view of a piezoelectric sensor using a thin film transistor according to a comparative example of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, the same or corresponding components are designated by the same reference numerals, and duplicate description between the embodiments will be omitted.

FIG. 1 is a schematic cross-sectional view showing a piezoelectric laminated sheet 100 according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the piezoelectric laminated sheet 101 according to the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing the piezoelectric laminated sheet 102 according to the third embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing the piezoelectric laminated sheet 103 according to the fourth embodiment of the present invention.

The piezoelectric laminated sheets 100, 101, 102, and 103 include at least a first conductive layer 1, a piezoelectric layer 2, an adhesive layer 3, a peeling layer 4, and a second conductive layer 5.

As shown in FIG. 1, in the piezoelectric laminated sheet 100, the first conductive layer 1 and the piezoelectric layer 2 are formed on the first substrate 6, and the adhesive layer 3 is formed on the piezoelectric layer 2. The release layer 4, the second conductive layer 5, and the second base material 7 are formed.

As shown in FIG. 2, in the piezoelectric laminated sheet 101, the first conductive layer 1 and the piezoelectric layer 2 are formed on the first substrate 6, and the adhesive layer 3 is formed on the piezoelectric layer 2. The release layer 4 and the second conductive layer 5 are formed.

As shown in FIG. 3, the piezoelectric laminated sheet 102 has a first conductive layer 1 and a piezoelectric layer 2 formed therein, and an adhesive layer 3, a release layer 4, and a second conductive layer are formed on the piezoelectric layer 2. Layer 5 is formed.

In the piezoelectric laminated sheet according to the embodiment of the present invention, the adhesive layer 3 is formed on the piezoelectric layer 2, and the release layer 4 and the second conductive layer 5 are formed on the adhesive layer 3. The piezoelectric layer 2 is sandwiched between the first conductive layer 1 and the second conductive layer 5, and is formed by applying an electric field between the first conductive layer 1 and the second conductive layer 5. The polarization treatment of 2 can be carried out.

Further, by providing the release layer 4 between the adhesive layer 3 and the second conductive layer 5, the second conductive layer 5 can be easily separated from the adhesive layer 3. Therefore, when the piezoelectric sensor is manufactured using the piezoelectric laminated sheet of the present invention, the second conductive layer 5 is peeled off from the piezoelectric laminated sheet and placed on the electrode of the piezoelectric sensor substrate on which an electronic circuit or the like is formed. The piezoelectric layer 2 can be easily attached by the adhesive layer 3. Further, the first conductive layer 1 can be used as it is as a common electrode of the piezoelectric sensor. Before peeling the release layer 4 and the second conductive layer 5, the piezoelectric laminated sheet is inspected for the piezoelectric characteristics of the piezoelectric layer 2 by using the first conductive layer 1 and the second conductive layer 5. This is possible, and it is possible to improve the yield of piezoelectric sensor fabrication by inspecting the piezoelectric sensor before fabrication and removing defective products.

As shown in FIG. 1, the piezoelectric laminated sheet of the present invention may be provided with the first base material 6 and the second base material 7. The difference between the piezoelectric laminated sheet 100 and the piezoelectric laminated sheet 101 is whether the second conductive layer 2 is formed on the second base material 5 or the second conductive layer 2 itself is used as the base material. Is the difference. Further, in the piezoelectric laminated sheet 102, the first conductive layer 1 and the second conductive layer 5 are used as the base materials of the piezoelectric laminated sheet, respectively.

Further, when the piezoelectric laminated sheet of the present invention is used to make a piezoelectric sensor, it can be made into an electronic device such as a pressure sensor, an infrared sensor, or a biological sensor by providing a sensor circuit (not shown). These structures can be appropriately changed depending on the type of electronic device to be used.

Hereinafter, each component of the piezoelectric laminated sheet 100, the piezoelectric laminated sheet 101, and the piezoelectric laminated sheet 102 will be described by taking a method for manufacturing the piezoelectric laminated sheet 100 as an example.

First, the first conductive layer 1 is formed. The first conductive layer may be formed on the first base material 6, or the first conductive layer itself may be used as the base material. When the first conductive layer 1 is formed on the first base material 6, the materials of the first base material 6 include polycarbonate, polyethylene sulfide, polyether sulfone, polyethylene terephthalate, polyethylene naphthalate, and cycloolefin polymer. , Triacetyl cellulose, polyvinyl fluoride film, ethylene-tetrafluoroethylene copolymer resin, weather resistant polyethylene terephthalate, weather resistant polypropylene, glass fiber reinforced acrylic resin film, glass fiber reinforced polycarbonate, polyimide, fluororesin, cyclic polyolefin resin , Glass, polyethylene glass, etc. can be used. The first base material 6 is not limited to these, but it is preferable to use a flexible material. Further, these may be used alone, but may also be used as a composite material in which two or more kinds are laminated.

When the first base material 6 is an organic film, a transparent gas barrier layer (not shown) can be formed in order to improve the durability of the piezoelectric laminated sheet. Examples of the material of the gas barrier layer include aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO), silicon nitride (SiN), silicon nitride (SiON), silicon carbide (SiC) and diamond-like carbon (DLC). Is not limited to these. Further, these gas barrier layers can be used by laminating two or more layers. The gas barrier layer may be formed on only one side of the first base material 6 using the organic film, or may be formed on both sides. The gas barrier layer can be formed by using a vacuum vapor deposition method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD (Chemical Vapor Deposition) method, a hot wire CVD method, a sol-gel method, or the like. It is not limited to these. Further, in order to improve the adhesion between the first base material 6 and the first conductive layer 1, a high adhesion layer is provided on the first base material 6, and the adhesion is improved by plasma treatment or corona treatment. It is also possible to let them do it.

The material of the first conductive layer 1 includes aluminum (Al), copper (Cu), molybdenum (Mo), chromium (Cr), titanium (Ti), tungsten (W), manganese (Mn), and niobium (Nb). , Metallic materials such as tantalum (Ta) and conductive metal oxide materials such as indium oxide (InO), tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), zinc oxide (IZO). Can be used, but is not limited thereto. These materials may be used in a single layer or as a laminate and an alloy.

For the formation of the first conductive layer 1, a vacuum film deposition method such as a vacuum deposition method or a sputtering method, a sol-gel method using a precursor of a conductive material, a method using nanoparticles, and inks thereof are used. A method of forming by a wet film forming method such as screen printing, letterpress printing, or an inkjet method can be used, but the present invention is not limited to these, and a known general method can be used.

When the first conductive layer 1 itself is used as a base material, materials such as aluminum foil, copper foil, and stainless steel foil can be used, but the present invention is not limited thereto.

Next, the piezoelectric layer 2 is formed on the first conductive layer 1. Piezoelectric organic polymer materials such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride trifluoroethylene copolymer (P (VDF-TrFE)), polylactic acid, and polyamino acid, and lead zirconate titanate can be used as materials for the piezoelectric layer 2. Piezoelectric ceramic materials such as lead acid (PZT), barium titanate (BTO), lead titanate (PTO), and fine particles of these piezoelectric ceramics dispersed in organic polymer materials, porous polypropylene, fluorine, etc. Organic electlet materials in which the charge is trapped in the resin can be used, but the present invention is not limited thereto.

In particular, when the piezoelectric sensor element is used as a flexible material, the material of the piezoelectric layer 2 is a highly flexible piezoelectric organic polymer material, a piezoelectric ceramic material dispersed in an organic material, or an organic material. Electret materials are preferably used.

The piezoelectric layer 2 may be formed by applying an ink obtained by dissolving an organic polymer material which is a base of a piezoelectric organic polymer material or an electret material in a solvent, an ink in which fine particles of piezoelectric ceramics are dispersed, or the like. However, a piezoelectric polymer material or an electret material formed into a film by an extrusion method or a stretching method can also be used. As the stretching method, a method in which the orientation of the molecular chain is controlled by the uniaxial stretching method is also preferably used. When the piezoelectric layer 2 is formed of a piezoelectric ceramic material, a vacuum film forming method such as a sputtering method or a wet film forming method such as a sol-gel method can be used, but the present invention is not limited to this. ..

The film thickness of the piezoelectric layer 2 is not particularly specified, but when it is applied as an ink of a piezoelectric organic polymer material, it is preferable to form a film with a film thickness of about 2 μm to 40 μm. When a piezoelectric ceramic material is used, it is preferably about 100 nm to 5 μm.

The piezoelectric layer 2 is imparted with piezoelectricity by being subjected to a polarization treatment. As a method of polarization treatment, a method of applying an electric field to the piezoelectric layer 2 or a method of trapping electric charges by corona treatment or the like when the material of the piezoelectric layer 2 is an electret material can be used.

Next, the adhesive layer 3 is formed. For the adhesive layer 3, a heat-active adhesive or a pressure-sensitive adhesive can be used. As these materials, elastomer materials such as rubber-based, acrylic-based, silicone-based, and urethane-based materials are used, and those in which additives are introduced and the adhesiveness thereof is appropriately adjusted can be used. Further, as the adhesive layer 3, a material to which conductivity is imparted can also be preferably used. For example, the conductive pressure-sensitive adhesive layer 3 can be formed by adding metal fine particles, carbon fine particles, carbon fiber, a conductive polymer, or the like to the pressure-sensitive adhesive layer 3.

For the bonding between the piezoelectric layer 2 and the adhesive layer 3, the material of the adhesive layer 3 may be applied on the piezoelectric layer 2, or the second conductive layer 5 on which the adhesive layer 3 and the release layer 4 are formed in advance may be applied. It may be formed by laminating.

The release layer 4 of the present invention is provided to separate the second conductive layer 5 from the adhesive layer 3, and known general materials such as silicone-based materials and non-silicone-based materials can be used. is there.

The release layer 4 can be formed by applying the above-mentioned release agent on the second conductive layer 5, but can be formed by a known general method.

The second conductive layer 5 may be formed on the second base material 7, or the second conductive layer 5 itself may be used as the base material. When the second conductive layer 5 is formed on the second base material 7, the same materials and methods as in the case of forming the first conductive layer 1 on the first base material 6 can be used.

Further, when the second conductive layer 5 itself is used as a base material, a material such as an aluminum foil, a copper foil, or a stainless steel foil can be used as in the case where the first conductive layer 1 is used as a base material. It can, but is not limited to these.

The piezoelectric laminated sheet according to the embodiment of the present invention produced as described above polarizes the piezoelectric layer 2 by applying an electric field between the first conductive layer 1 and the second conductive layer 5. It is possible.

As the polarization treatment, it is possible to perform the polarization treatment by applying an electric field of about 100 V / μm between the first conductive layer 1 and the second conductive layer 5. Further, the electric field may be carried out by using a DC power source or an AC power source.

As a method of confirming the polarization treatment, an electric field is applied between the first conductive layer 1 and the second conductive layer 5 by using a Sawyer tower circuit, and the hysteresis curve is observed to obtain the coercive electric field (EC) and There is a method of measuring residual polarization (Pr). The hysteresis curve can also be measured at the same time as the polarization treatment.

Further, as shown in FIG. 4, the piezoelectric laminated sheet of the present invention has a configuration like the piezoelectric laminated sheet 103 in which the second release layer 8 and the second adhesive layer 9 are provided on the first conductive layer 1. May be.

Like the piezoelectric laminated sheet 103, the first conductive layer 1 and the second conductive layer 5 can be peeled off from the adhesive layer 3 and the adhesive layer 9 installed on both sides of the piezoelectric layer 2, respectively. In manufacturing a piezoelectric sensor, it is possible to first peel off the conductive layer on one side and attach it to the piezoelectric sensor circuit board, and then peel off the other conductive layer and attach it to another circuit board or a substrate with electrodes. Therefore, even a piezoelectric sensor having a more complicated structure can be easily formed.

The piezoelectric laminated sheet of the present invention can detect applied pressure, vibration, bending, infrared rays, etc. by connecting to a circuit for detecting a signal output from the piezoelectric layer 2, and is particularly a thin film transistor. By using the above to make an active sensor element, it is possible to detect with a large area and high sensitivity.

Further, in order to make the piezoelectric sensor of the present invention a flexible piezoelectric sensor having flexibility, it is preferable to use a flexible thin film transistor having flexibility as the thin film transistor. In this respect, as the flexible thin film transistor, a flexible organic thin film transistor using an organic semiconductor material having high flexibility is preferably used.

The piezoelectric sensor according to the embodiment of the present invention will be described with reference to the drawings as an example of combining a piezoelectric laminated sheet and a thin film transistor.

FIG. 5 is a piezoelectric sensor 200 manufactured by combining the piezoelectric laminated sheet 100 of the present invention and a thin film transistor. Further, FIG. 6 is a piezoelectric sensor 201 produced by combining the piezoelectric laminated sheet 100 of the present invention and a thin film transistor. The difference between FIGS. 5 and 6 is that the electrodes of the thin film transistor connected to the piezoelectric laminated sheet are different.

The piezoelectric sensor of the present invention is used by applying an arbitrary voltage to the gate voltage to adjust the conductivity of the channel portion formed of the semiconductor layer of the thin film transistor. Therefore, the structure of the thin film transistor in the piezoelectric sensor of the present invention is preferably a bottom gate structure.

The base material 21 of the thin film of the present invention is polycarbonate, polyethylene sulfide, polyether sulfone, polyethylene terephthalate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyvinyl fluoride film, ethylene-tetrafluoroethylene copolymer resin, weather resistance. Polyethylene terephthalate, weather-resistant polypropylene, glass fiber reinforced acrylic resin film, glass fiber reinforced polycarbonate, polyimide, fluororesin, cyclic polyolefin resin, glass, quartz glass, etc. can be used, but are not limited thereto. Absent. These may be used alone, or two or more kinds may be laminated and used as the substrate 21. When the piezoelectric sensor of the present invention is used as a flexible sensor, it is preferable to use a flexible base material for the base material 21 of the thin film transistor.

When the substrate 21 is an organic film, a transparent gas barrier layer (not shown) can be formed in order to improve the durability of the organic thin film transistors 100 and 101. Examples of the material of the gas barrier layer include aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO), silicon nitride (SiN), silicon nitride (SiON), silicon carbide (SiC) and diamond-like carbon (DLC). Is not limited to these. Further, these gas barrier layers can be used by laminating two or more layers. The gas barrier layer may be formed on only one side of the substrate 1 using the organic film, or may be formed on both sides. The gas barrier layer can be formed by using a vacuum vapor deposition method, an ion plating method, a sputtering method, a laser ablation method, a plasma CVD (Chemical Vapor Deposition) method, a hot wire CVD method, a sol-gel method, or the like. It is not limited to these.

Next, the gate electrode 22 is formed on the substrate 21. The gate electrode 22, the source electrode 24, and the drain electrode 25 do not need to be clearly separated from each other in the electrode portion and the wiring portion, and are hereinafter referred to as electrodes as constituent elements of each thin film transistor.

The gate electrode 22 has gold (Au), platinum (Pt), aluminum (Al), silver (Ag), copper (Cu), molybdenum (Mo), chromium (Cr), titanium (Ti), and tungsten (W). , Manganese (Mn), Niobium (Nb), Tantal (Ta) and other metal materials, indium oxide (InO), tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), indium tin oxide (ITO) Conductive metal oxide materials such as IZO) can be used, but are not limited thereto. These materials may be used in a single layer or as a laminate and an alloy.

For the formation of the gate electrode 22, a vacuum film deposition method such as a vacuum vapor deposition method or a sputtering method, a sol-gel method using a precursor of a conductive material, a method using nanoparticles, etc., are used as inks. A method of forming by a wet film forming method such as screen printing, letterpress printing, or an inkjet method can be used, but the present invention is not limited to these, and a known general method can be used. For example, patterning can be performed by protecting the pattern-forming portion with a resist or the like using a photolithography method and removing unnecessary portions by etching, or by directly patterning using a printing method or the like. Is not limited to these methods, and a known general patterning method can be used.

Next, the gate insulating layer 23 is formed on the gate electrode 22. The gate insulating layer 23 is provided at least on the gate electrode 22 in order to electrically insulate the gate electrode 22 from the electrodes such as the source electrode 24 and the drain electrode 25, but is outside the gate electrode 22 and other electrodes. It may be provided on the entire surface of the substrate 21 except for the wiring portion used for connection with.

The gate insulating layer 23 includes silicon oxide (SiO _x ), aluminum oxide (AlO _x ), tantalum oxide (TaO _x ), yttrium oxide (YO _x ), zirconium oxide (ZrO _x ), hafnium oxide (HfO _x ), and the like. Oxide-based insulating materials, silicon nitride (SiN _x ), silicon oxide (SiON), polyacrylates such as polymethylmethacrylate (PMMA), polyvinyl alcohol (PVA), organic insulating materials such as polyvinylphenol (PVP), etc. Can be used, but is not limited to these. These may be a single layer or two or more layers, may be an inorganic-organic hybrid thin film, or may have a composition inclined in the growth direction. Further, the surface energy of the gate insulating layer 23 can be controlled by subjecting the surface of the gate insulating layer 23 to a surface treatment such as a self-assembled monolayer.

The resistivity of the gate insulating layer 23 is preferably 10 ¹¹ Ωcm or more, more preferably 10 ¹⁴ Ωcm or more, in order to suppress the leakage current in the organic thin film transistor.

Next, the source electrode 24 and the drain electrode 25 are formed. The source electrode 24 and the drain electrode 25 are formed so as to be separated from each other, and the source electrode 24 and the drain electrode 25 may be formed by different steps and different materials, but the same on the gate insulating layer 23. When formed in layers, it is preferable to form the source electrode 24 and the drain electrode 25 at the same time.

The same material and forming method as the gate electrode 22 can be used for the source electrode 24 and the drain electrode 25, but the work function is the HOMO level of the semiconductor layer 26 in view of the contact resistance with the semiconductor layer 26. It is preferably about the same. The work functions of the source electrode 24 and the drain electrode 25 can be appropriately adjusted by using surface treatment or the like.

For the measurement of the work functions of the source electrode 24 and the drain electrode 25, known general methods such as ultraviolet photoelectron spectroscopy (UPS) and atmospheric photoelectron spectroscopy can be used, but it relates to the embodiment of the present invention. Since the pattern size of the patterned source electrode 24 and drain electrode 25 is small and it may be difficult to directly measure the work function, in that case, measurement is performed separately using a measurement substrate having the same configuration. , Can be an alternative.

Next, the semiconductor layer 26 is formed between the source electrode 24 and the drain electrode 25 so as to connect the source electrode 24 and the drain electrode 25. The region of the semiconductor layer 26 in which the source electrode 24 and the drain electrode 25 are connected by the semiconductor layer 26 and function as an organic thin film transistor is generally referred to as a channel region, and such a name is also used in the present invention. There is.

For the semiconductor layer 26, low molecular weight semiconductors such as pentacene and derivatives thereof, polythiophene, polyallylamine, fluorenbithiophene copolymers, and high molecular weight organic semiconductor materials such as derivatives thereof can be used. , Not limited to these.

The semiconductor layer 26 can be formed by a wet film forming method such as letterpress printing, screen printing, an inkjet method, or nozzle printing using a solution in which an organic semiconductor material is dissolved or dispersed as an ink, or a powder of an organic semiconductor material. It can also be formed by a method such as vapor deposition of crystals in a vacuum state. The semiconductor layer 26 is not limited to these, and a known general method can also be used.

A semiconductor protective layer 27 can be formed on the semiconductor layer 26 in order to protect the element characteristics of the organic thin film transistor from the influence of the outside world and keep them good.

The semiconductor protective layer 27 is preferably formed by using an insulating material as shown in the gate insulating layer 23 so as not to affect the operation of the thin film transistor element. Specifically, it is desirable that the resistivity is 10 ¹¹ Ωcm or more, more preferably 10 ¹⁴ Ωcm or more.

Further, an interlayer insulating film 28 can be provided on the source electrode 24 and the drain electrode 25, the semiconductor layer 26, or the semiconductor protective layer 27. The interlayer insulating film 28 can be provided for insulation between the upper electrode 29 and the source electrode 24 or the drain electrode 25, which are provided later. Therefore, it is desirable that the resistivity is 10 ¹¹ Ωcm or more, more preferably 10 ¹⁴ Ωcm or more.

In the case of the configuration in which the upper electrode 29 and the drain electrode 25 are connected as shown in FIG. 6, it is possible to provide a through hole 35 in the interlayer insulating film 28 on the drain electrode 25 to obtain conduction.

The upper electrode 29 for exerting the change of state of the electric charge of the piezoelectric layer 2 on the semiconductor layer 26 can be formed on the interlayer insulating film 28. The upper electrode 29 can be formed by the same material and forming method as the gate electrode 22.

The upper electrode 29 may be connected to the drain electrode 25, and can be appropriately selected depending on the application of the piezoelectric sensor and its configuration.

The piezoelectric laminated sheet 100 and the thin film transistor of the present invention peel off and remove the second conductive layer 5 and the second base material 7 on which the release layer 4 is formed of the piezoelectric laminated sheet 100, and the piezoelectric laminated sheet is adhered. A piezoelectric sensor can be manufactured by laminating the layer 3 and the upper electrode 29 of the thin film transistor so as to be in contact with each other.

The piezoelectric laminated sheet and the thin film transistor may be laminated and bonded using a roller or the like, or may be arranged on a flat plate and then bonded so as to be pressed. The bonding can be carried out in the air, but it can also be carried out in an inert atmosphere or under reduced pressure in order to eliminate the influence of the outside air. In addition, it is possible to bond them better by bonding them while heating.

Further, in order to protect the piezoelectric sensor after bonding from external influences, the end portion thereof may be sealed with a sealing agent, or a barrier film may be attached to one or both sides thereof to protect the sensor. good.

(Example 1)
As Example 1, the piezoelectric laminated sheet 100 shown in FIG. 1 was produced.

A polyethylene naphthalate (PEN) film on which aluminum was formed was used as the first base material 6 on which the first conductive layer 1 was laminated. The thickness of the PEN film was 50 μm, and aluminum was formed to a thickness of about 100 nm by a vapor deposition method.

An ink obtained by dissolving polyvinylidene fluoride trifluoroethylene copolymer (P (VDF-TrFE)) as a piezoelectric layer 2 in cyclopentanone at a concentration of 15 wt% on the first conductive layer 1 by a bar coating method. Filmed. Then, it was baked in an oven heated to 120 ° C. for 3 hours. The film thickness of the piezoelectric layer 2 after firing was about 20 μm.

Further, an acrylic pressure-sensitive adhesive was applied onto the piezoelectric layer 2 and dried to form the pressure-sensitive adhesive layer 3.

As the second base material 7 on which the second conductive layer 5 was laminated, a polyethylene terephthalate (PET) film having an aluminum film formed was used. The thickness of the PET film was 50 μm, and aluminum was formed to a thickness of about 100 nm by a vapor deposition method.

An ink containing a mold release agent made of a silicone resin was applied onto the second conductive layer 5 and dried to form the release layer 4.

After that, the first base material 6 on which the first conductive layer 1, the piezoelectric layer 2, and the adhesive layer 3 are formed, and the second base material 7 on which the second conductive layer 5 and the release layer 4 are formed are laminated. And joined.

Further, the first embodiment of the present invention is carried out by applying an electric field of about 100 V / μm, that is, a voltage of 2 kV between the first conductive layer 1 and the second conductive layer 5 to carry out the polarization treatment of the piezoelectric layer 2. The piezoelectric laminated sheet 100 according to the above embodiment was formed.

(Example 2)
(Manufacturing of piezoelectric sensor)
In order to produce the piezoelectric sensor 200 of the present invention, a thin film transistor was produced. Polyimide was used as the base material 21. Specifically, using 0.7 mm non-alkali glass as a supporting base material, a polyimide varnish was applied, dried and fired to form a base material 21 made of polyimide on the supporting base material. The film thickness of the base material 21 was 20 μm.

An aluminum-neodymium (0.2 at%) alloy (Al-Nd) was formed on the substrate 21 with a film thickness of 100 nm by a DC magnetron sputtering method, and patterned into a desired shape by a photolithography method. .. Specifically, after applying a photosensitive positive photoresist to the formed Al-Nd alloy, mask exposure and development with an alkaline developer were performed to form a resist pattern having a desired shape. Further, etching was performed with an etching solution to dissolve an unnecessary Al—Nd alloy. Then, the photoresist was removed with a resist stripping solution to form a gate electrode 22 having a desired shape (hereinafter, such a patterning method is abbreviated as a photolithography method).

A photocurable acrylic resin is applied onto the base material 21 on which the gate electrode 22 is formed by using a slit coating method, mask exposure and development with an alkaline developer are performed, and then the gate insulating layer 23 is fired at 150 ° C. Formed. The film thickness of the gate insulating layer 23 after firing was 1 μm.

Ag nanoparticle ink was dropped into a desired shape on the base material 21 on which the gate insulating layer 23 was formed by an inkjet method and fired at 150 ° C. to form a source electrode 24 and a drain electrode 25. The film thickness of the source electrode 24 and the drain electrode 25 is about 100 nm.

Then, the base material 21 on which the source electrode 24 and the drain electrode 25 were formed was immersed in an isopropyl alcohol (IPA) solution of pentafluorobenzenethiol adjusted to a concentration of 1 mmol / L, washed with IPA, and the source electrode 24 and the drain electrode were washed. A surface treatment with a self-integrating film was performed on 25.

Subsequently, mesitylene obtained by dissolving 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS-pentacene) as an organic semiconductor material in the base material 21 on which the source electrode 24 and the drain electrode 25 were formed at a concentration of 0.1 wt%. The solution was applied and patterned by an inkjet method to form a semiconductor layer 26.

Further, a fluororesin material Cytop (manufactured by AGC) was applied so as to cover the semiconductor layer 26 to form the semiconductor protective layer 27.

Then, the interlayer insulating layer 28 is formed in the same manner as the gate insulating layer 23 using the photosensitive acrylic resin, and then the upper electrode 29 is formed in the same manner as in the gate electrode 22 to produce the thin film transistor according to the embodiment of the present invention. did.

In order to bond the piezoelectric laminated sheet 100 and the thin film transistor, the second base material 7 on which the second conductive layer 5 and the release layer 4 were formed was peeled off. A piezoelectric laminated sheet from which the second base material 7 was peeled off was bonded to a thin film transistor using a laminator in which a laminated roll was heated to 80 ° C. to prepare a piezoelectric sensor 200 according to an embodiment of the present invention. In the piezoelectric sensor 200, the first conductive layer 1 of the piezoelectric laminated sheet functions as a counter electrode corresponding to the upper electrode 29.

(Comparison example)
As a comparative example, the piezoelectric sensor 300 shown in FIG. 7 was manufactured.

The thin film transistor used for the piezoelectric sensor 300 according to the comparative example of the present invention was produced up to the upper electrode 29 by the same method as in Example 2.

Then, an ink obtained by dissolving polyvinylidene fluoride trifluoroethylene copolymer (P (VDF-TrFE)) as a piezoelectric layer 30 in cyclopentanone at a concentration of 15 wt% was formed on the upper electrode 29 by a bar coating method. .. Then, it was baked in an oven heated to 120 ° C. for 3 hours. The film thickness of the piezoelectric layer 2 after firing was about 20 μm.

Further, an Al—Nd alloy was formed on the piezoelectric layer 30 by DC magnetron sputtering to form a counter electrode 31.

At present, since the piezoelectric layer 30 of the piezoelectric sensor 300 is not polarized, it is necessary to perform the polarization treatment so that the piezoelectric layer 30 has spontaneous polarization in order to function as the piezoelectric sensor.

A DC voltage of 2 kV was applied to the upper electrode 29 and the counter electrode 31 in order to apply an electric field equivalent to 100 V / μm to the piezoelectric layer 30.

Through the above steps, a piezoelectric sensor using the piezoelectric laminated sheet according to Example 1 and the organic thin film transistor according to Example 2 and Comparative Example was produced.

In the piezoelectric laminated sheet 100 according to the first embodiment, by performing the polarization treatment of the piezoelectric layer 2 during the manufacturing process, the piezoelectric layer 3 can be used as a piezoelectric sensor only by being attached to the thin film transistor using the adhesive layer 3. It has become.

Further, the piezoelectric sensor 200 according to the second embodiment is manufactured by attaching the piezoelectric laminated sheet of the first embodiment to the thin film transistor, and there is no need for polarization treatment after the attachment.

On the other hand, the piezoelectric sensor 300 according to the comparative example differs from the piezoelectric sensor 200 of the second embodiment in that the piezoelectric layer 30 is directly formed on the thin film transistor and the polarization treatment is performed without using the piezoelectric laminated sheet. It is a point.

When the piezoelectric sensor 200 and the piezoelectric sensor 300 were compared, in the piezoelectric sensor 300 according to the comparative example, when pressure was applied on the piezoelectric sensor, a sufficient change in the characteristics of the thin film was not observed, and the thin film operated normally. Not shown. This is because a large voltage was applied to the thin film transistor during the polarization treatment of the piezoelectric layer of the piezoelectric sensor according to the comparative example, so that the element was destroyed. On the other hand, in the piezoelectric sensor 200, when pressure was applied onto the piezoelectric sensor, a change in the characteristics of the thin film transistor was observed. Specifically, by applying pressure, the threshold value in the current transfer characteristics of the thin film transistor was shifted, and a change in the drain current value at a predetermined gate current was observed. Therefore, it was confirmed that the piezoelectric sensor 200 of Example 2 produced by using the piezoelectric laminated sheet 100 according to Example 1 of the present invention works.

By using the piezoelectric laminated sheet of the present invention, it is possible to easily make a piezoelectric sensor by simply attaching the piezoelectric laminated sheet to the electrode of the sensor circuit without destroying the piezoelectric sensor circuit due to the voltage of the polarization process. It becomes. Further, the piezoelectric laminated sheet of the present invention has an adhesive layer 3 so that the sensor circuit and the piezoelectric layer 2 can be reliably joined, and when the piezoelectric layer 2 and the transistor are fixed only by electrostatic force ( Compared with Patent Document 1), it is possible to form a piezoelectric sensor with good yield without peeling during production.

Further, since the piezoelectric laminated sheet of the present invention can be produced by applying and laminating the piezoelectric layer 2, it can also be produced by roll-to-roll with high productivity. In addition, it can be stored as it is even after polarization treatment, and when manufacturing a piezoelectric sensor, it can be cut out to the desired size and used, and it can be used for piezoelectric sensors of various sizes. It can be said that the efficiency is high.

1 1st conductive layer 2 Piezoelectric layer 3 Adhesive layer 4 Peeling layer 5 2nd conductive layer 6 1st base material 7 2nd base material 8 2nd peeling layer 9 2nd adhesive layer

Claims (9)

It has at least a first conductive layer, a piezoelectric layer in contact with the first conductive layer, an adhesive layer, a release layer, and a second conductive layer, and the release layer and the first. A piezoelectric laminate sheet, wherein the conductive layer 2 is a piezoelectric laminate that can be peeled off from the adhesive layer. The piezoelectric laminated sheet according to claim 1, wherein the adhesive layer has conductivity. The piezoelectric laminated sheet according to claim 1 or 2, wherein the piezoelectric layer has spontaneous polarization. The piezoelectric laminated sheet according to any one of claims 1 to 3, wherein the piezoelectric layer is an organic polymer material. The piezoelectric laminated sheet according to any one of claims 1 to 3, wherein the piezoelectric layer is an organic electret material. A step of forming a laminate in which a first conductive layer, a piezoelectric layer, an adhesive layer, a peeling layer, and a second conductive layer are laminated in this order, and between the first conductive layer and the second conductive layer. A method for producing a piezoelectric laminated sheet, which comprises a step of applying an electric field to carry out a polarization treatment of the piezoelectric layer. A piezoelectric sensor having at least a first conductive layer, a piezoelectric layer in contact with the first conductive layer, an adhesive layer, and a sensor electrode layer bonded so as to be in contact with the adhesive layer. The piezoelectric sensor according to claim 7, wherein the adhesive layer has conductivity. A step of manufacturing a piezoelectric laminated sheet by the manufacturing method according to claim 6 and
A step of peeling the peeling layer and the second conductive layer of the manufactured piezoelectric laminated sheet from the adhesive layer, and
A method for manufacturing a piezoelectric sensor, which comprises a step of attaching the piezoelectric laminated sheet from which the second conductive layer has been peeled off to an electrode of a sensor substrate.