KR100802882B1 - Piezoelectric device, its manufacturing method, and touch panel device - Google Patents

Abstract

The piezoelectric element X includes the substrate 11, the piezoelectric film 12, the first electrode 13 and the second electrode 14, and the first electrode 13 and / or the second electrode 14 A metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au is interposed between the substrate 11 and the piezoelectric film 12 in an amount of 0.1 to 3 wt% Containing Al alloy.

Piezoelectric element, interdigital transducer, touch panel, surface acoustic wave, excitation means

Description

TECHNICAL FIELD [0001] The present invention relates to a piezoelectric element, a manufacturing method thereof, and a touch panel device.

The present invention relates to a piezoelectric element capable of exciting a surface acoustic wave, a manufacturing method thereof, and a touch panel device having a piezoelectric element as an excitation means and receiving means.

As a means for inputting to a computer system in an FA apparatus, an OA apparatus and a measuring apparatus, a touch panel apparatus may be employed. The touch panel device is provided integrally with the display of the device to detect a position where a finger or the like is in contact with the display surface. Predetermined processing is executed in the computer system of the apparatus based on the data relating to the image displayed on the display and the data relating to the contact position detected by the touch panel apparatus.

2. Description of the Related Art In the technical field of a touch panel device, a SAW touch panel device that detects a contact position using a surface acoustic wave (SAW) has recently been attracting attention. The SAW touch panel device includes, for example, a transparent substrate having a detection region and a peripheral region surrounding the detection region, and a plurality of excitation means and a plurality of reception means provided in the peripheral region of the substrate . The excitation means and the receiving means are each composed of a piezoelectric element. Such a SAW touch panel device is described in, for example, Japanese Patent Application Laid-Open Nos. 6-149459 and 10-55240.

The piezoelectric element constituting the excitation means and the reception means includes, for example, an interdigital transducer (IDT) in which a pattern is formed for each element on the periphery region of the substrate, and a piezoelectric film Lt; / RTI > The IDT is composed of a pair of comb electrodes, and each comb electrode has a plurality of electrode fingers (electrode fingers) parallel to each other. The electrode fingers of one comb electrode and the electrode fingers of the other comb electrode are arranged alternately and in parallel. The piezoelectric film is made of a piezoelectric material that exhibits an electric field (piezoelectric effect) due to distortion and a property of causing distortion (reverse piezoelectric effect) due to the application of an electric field.

When an AC voltage is applied to the IDT of the piezoelectric element as the excitation means, an AC electric field is generated between adjacent electrode fingers. Then, the piezoelectric film corresponding to the electrode fingers is distorted due to the inverse piezoelectric effect, and the predetermined acoustic wave is excited by the entirety of the IDTs in the piezoelectric film. At this time, the acoustic wave having the same wavelength as the electrode finger pitch is strongly excited. The excited acoustic wave propagates on the substrate surface and reaches the piezoelectric element as the receiving means. In this device, an AC electric field is generated between the electrode fingers of the IDT by the piezoelectric effect of the piezoelectric film. And an alternating current is output from the IDT of the device.

In operation of the SAW touch panel device, surface acoustic waves are generated from the respective piezoelectric elements as the exciting means, and the surface acoustic waves propagate through the detection region of the substrate and are received by the specific piezoelectric element as the receiving means. When a finger or the like is in contact with the detection region, the amplitude of the surface acoustic wave passing through the contact position is attenuated. By detecting and analyzing this attenuation, the contact position in the detection region is specified or detected.

In such a SAW touch panel device, in the excitation piezoelectric device, the higher the electromechanical conversion efficiency is, the more the acoustic wave is excited with respect to the applied voltage. On the other hand, in a receiving piezoelectric element, the higher the electromechanical conversion efficiency, the more efficiently the AC current is output based on the received acoustic wave. Therefore, in the SAW touch panel device, the higher the electromechanical conversion efficiency of each piezoelectric element, the smaller the insertion loss (dB) in the transmission and reception of signals between the pair of piezoelectric elements becomes, and as a result, And the detection accuracy of the apparatus is increased.

However, according to the conventional SAW touch panel device, since a sufficiently high electromechanical conversion efficiency can not be obtained in the piezoelectric element, the driving voltage can not be sufficiently reduced, and the required detection precision can not be obtained There is a case.

It is an object of the present invention to provide a piezoelectric element having a high electromechanical conversion efficiency, a manufacturing method thereof, and an SAW type touch panel device having such a piezoelectric element as an excitation means and a receiving means, .

According to a first aspect of the present invention, there is provided a piezoelectric element. The piezoelectric element includes a substrate, a piezoelectric film, a first electrode, and a second electrode. The first electrode and / or the second electrode are interposed between the substrate and the piezoelectric film, and a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, And an Al alloy containing 0.1 to 3 wt%. When the Al alloy contains a plurality of metals selected from the group, the content of each additive metal in the Al alloy is in the range of 0.1 to 3 wt%.

Conventionally, a piezoelectric film in a predetermined piezoelectric element is formed by forming a piezoelectric material by a sputtering method, and the substrate is heated at the time of film formation. When the substrate is heated, the electrode already formed on the substrate (for example, the IDT of the conventional piezoelectric element described above) is heated together with the substrate, and due to the difference in thermal expansion coefficient between the substrate and the electrode, (partial peeling of the electrode from the substrate surface) occurs. It is known that the greater the hillocks or the larger the hillocks, the lower the electromechanical conversion efficiency of the piezoelectric element concerned. In a conventional piezoelectric device in a SAW touch panel device, Al is often used as a material for forming the IDT, which is an electrode. Al is small in electrical resistance, inexpensive, and easy to process. However, hillocks are particularly likely to occur and grow in the Al electrode.

In the manufacture of the piezoelectric element according to the first aspect of the present invention, after the first electrode and the second electrode are formed in a predetermined pattern on the substrate, a piezoelectric film is formed on the substrate so as to cover these electrodes. Alternatively, after a first electrode is formed in a predetermined pattern on a substrate, a piezoelectric film is formed on the substrate so as to cover the first electrode, and a second electrode is formed on the piezoelectric film. Alternatively, after the second electrode is formed in a predetermined pattern on the substrate, a piezoelectric film is formed on the substrate so as to cover the second electrode, and the first electrode is formed on the piezoelectric film. In either method, when the piezoelectric film is formed, the substrate is heated similarly to the conventional method, and thus the electrode already formed on the substrate is heated.

However, in the piezoelectric element according to the first aspect, the electromechanical conversion efficiency higher than that of the conventional piezoelectric element can be obtained. The electrode (the first electrode and / or the second electrode) interposed between the substrate and the piezoelectric film is made of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, In an amount of 0.1 to 3 wt%, and is harder to thermally expand than an electrode made of pure Al. In the case where the electrode which has already been formed on the substrate at the time of forming the piezoelectric film and which is interposed between the substrate and the piezoelectric film in the piezoelectric element to be produced is made of the Al alloy as described above, It is considered that the number and size of hillocks do not occur in the electrodes or even if hillocks are generated, and as a result, a high electromechanical conversion efficiency can be obtained in the piezoelectric elements.

In a first aspect of the present invention, in a preferred embodiment, the first electrode is interposed between the substrate and the piezoelectric film, and the second electrode is formed on the piezoelectric film. In this configuration, for applying a voltage to the piezoelectric film, first and second electrodes sandwiching the piezoelectric film are used. In this case, it is preferable that the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, and the first electrode is a portion facing the plurality of branch electrodes across the piezoelectric film . In this case, when the thickness of the piezoelectric film is h and the electrode period of the plurality of branch electrodes is?, The value of h /? Is preferably 0.005 to 0.1. This range of h / l is very suitable for obtaining high electromechanical conversion efficiency.

In a first aspect of the present invention, in another preferred embodiment, the first electrode and the second electrode are interposed between the substrate and the piezoelectric film to constitute an interdigital transducer (IDT). In this configuration, for applying voltage to the piezoelectric film, an IDT interposed between the substrate and the piezoelectric film is used.

According to a second aspect of the present invention, a method of manufacturing a piezoelectric element is provided. This manufacturing method is characterized in that a first electrode made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, A step for forming a second electrode on the piezoelectric film, a step for forming a second electrode on the piezoelectric film, a step for forming a second electrode on the piezoelectric film, .

According to this method, the piezoelectric element according to the first aspect of the present invention can be suitably manufactured. Therefore, according to the second aspect of the present invention, a high electromechanical conversion efficiency can be obtained in the piezoelectric element to be manufactured.

According to a third aspect of the present invention, another method of manufacturing a piezoelectric element is provided. This manufacturing method is characterized in that a first electrode made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, A step for etching the surface of the first electrode, a step for forming a piezoelectric film overlapping the first electrode on the substrate, and a step for forming the second electrode on the piezoelectric film do.

According to this method, the piezoelectric element according to the first aspect of the present invention can be suitably manufactured. Therefore, according to the third aspect of the present invention, a high electromechanical conversion efficiency can be obtained in the piezoelectric element to be manufactured.

In a third aspect of the present invention, preferably, the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, and the first electrode is provided with a piezoelectric film And has portions facing each other across the plurality of branch electrodes.

According to a fourth aspect of the present invention, another method of manufacturing a piezoelectric element is provided. This manufacturing method forms an IDT made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, A process for removing an oxide film on the surface of the IDT, and a process for forming a piezoelectric film on the substrate overlapping the IDT.

According to this method, the piezoelectric element according to the first aspect of the present invention can be suitably manufactured. Therefore, also in the fourth aspect of the present invention, a high electromechanical conversion efficiency can be obtained in the piezoelectric element to be produced.

According to a fifth aspect of the present invention, another method of manufacturing a piezoelectric element is provided. This manufacturing method forms an IDT made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, A step for etching the surface of the IDT, and a step for forming a piezoelectric film on the substrate which is superimposed on the IDT.

According to this method, the piezoelectric element according to the first aspect of the present invention can be suitably manufactured. Therefore, also in the fifth aspect of the present invention, a high electromechanical conversion efficiency can be obtained in the piezoelectric element to be produced.

According to a sixth aspect of the present invention, there is provided a touch panel device. The touch panel device comprises a substrate including a detection region and a peripheral region surrounding the detection region, excitation means provided in the peripheral region for exciting a surface acoustic wave in the substrate, And reception means for receiving the acoustic waves. The exciting means and / or receiving means include a piezoelectric film, a first electrode, and a second electrode. Wherein the first electrode and / or the second electrode is made of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au, 3 wt% Al alloy.

The exciting means and / or the receiving means of the touch panel device having such a constitution is constituted by the piezoelectric element of high electromechanical conversion efficiency according to the first aspect. Therefore, the touch panel device according to the sixth aspect of the present invention is suitable for reducing the driving voltage and improving the detection precision.

In a sixth aspect of the present invention, in a preferred embodiment, the first electrode is interposed between the substrate and the piezoelectric film, and the second electrode is formed on the piezoelectric film. In this case, it is preferable that the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, and the first electrode is provided so as to face the plurality of branch electrodes Region. In this case, preferably, the thickness of the piezoelectric film is h and the electrode period of the plurality of branch electrodes is?, The value of h /? Is 0.005 to 0.1.

In a sixth aspect of the present invention, in another preferred embodiment, the first electrode and the second electrode are interposed between the substrate and the piezoelectric film to constitute the IDT.

In the first to sixth aspects of the present invention, preferably, the piezoelectric film is made of ZnO doped with Mn. The constituent material of the electrode sandwiched between the substrate and the piezoelectric film may diffuse into the piezoelectric film under a high temperature and diffusion of the electrode constituting material into the piezoelectric film often lowers the electromechanical conversion efficiency of the piezoelectric element . When Mn is doped into the piezoelectric material ZnO, the diffusion of Al, for example, the electrode constituent material into the piezoelectric film is suppressed. Therefore, this configuration is suitable for obtaining a high electromechanical conversion efficiency in the piezoelectric element.

1 is a plan view of a piezoelectric element according to a first embodiment of the present invention;

Fig. 2 is a cross-sectional view taken along the line II-II in Fig. 1; Fig.

Figs. 3A to 3C are diagrams showing a manufacturing method of the piezoelectric element shown in Fig. 1, and each drawing is a partial sectional view. Fig.

4 is a plan view of a piezoelectric element according to a second embodiment of the present invention;

5 is a cross-sectional view taken along the line V-V of Fig.

6A to 6C are diagrams showing a manufacturing method of the piezoelectric element shown in Fig. 4, wherein each drawing is a partial sectional view. Fig.

7 is a view showing a touch panel device according to a third embodiment of the present invention.

8 is a partially enlarged view of the touch panel device shown in Fig.

9 is a view showing a touch panel device according to a fourth embodiment of the present invention.

10 is a partially enlarged view of the touch panel device of Fig.

11 is a view showing a filter having the piezoelectric element shown in Fig.

12 is a diagram showing the results of the insertion loss measurement for each filter in the first to third embodiments and the comparative example.

Fig. 13 is a view showing the annealing time dependency of the insertion loss for each filter in the first and fourth embodiments; Fig.

1 and 2 show a piezoelectric element X according to a first embodiment of the present invention. The piezoelectric element X is provided with a substrate 11, a piezoelectric film 12 and electrodes 13 and 14 so as to excite and receive surface acoustic waves.

The substrate 11 has a function of ensuring the rigidity of the element, and is a medium through which surface acoustic waves propagate. The substrate 11 is, for example, a non-piezoelectric substrate such as a transparent glass substrate.

The piezoelectric film 12 is made of a piezoelectric material exhibiting a property of causing an electric field (distortion effect) due to distortion and a property of causing distortion (an inverse piezoelectric effect) due to the application of an electric field. As such a piezoelectric material, for example, ZnO or AlN doped with Mn can be adopted. The thickness h of the piezoelectric film 12 is, for example, 1.0 to 3.0 占 퐉.

The electrode 13 is interposed between the substrate 11 and the piezoelectric film 12 and is made of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, And an Al alloy containing 0.1 to 3 wt%. When the Al alloy contains a plurality of metals selected from the group, the content of each additive metal in the Al alloy is in the range of 0.1 to 3 wt%. The electrode (13) is continuous with the terminal (15) having a portion exposed to the outside. The thickness of the electrode 13 is, for example, 300 to 600 nm.

The electrode 14 is formed on the piezoelectric film 12 and has a comb structure composed of a base portion 14a and a plurality of branch electrodes 14b. The plurality of branch electrodes 14b extend from the base portion 14a and are also parallel to each other. The plurality of branch electrodes 14b parallel to each other may be curved or curved instead of the straight line as shown in Fig. Further, the branch electrode 14b is opposed to the electrode 13 through the piezoelectric film 12.

The electrode 14 has a thickness of 300 to 600 nm and the width d ₁ of each branch electrode 14b is, for example, 40 to 60 μm, and the electrode period (λ ₁ ) of the branch electrode 14b is For example, 100 to 150 mu m. It is preferable that the thickness h of the piezoelectric film 12 and the electrode period? ₁ of the branch electrode 14b have a relationship of 0.005? H /? ₁ ? 0.1.

The electrode 14 is made of a predetermined conductive material. As the constituent material of the electrode 14, the same material as that of the electrode 13 may be employed. Further, the electrode 14 is connected to the terminal 16 continuously.

3A to 3C show a manufacturing method of the piezoelectric element X. Fig. 3A, the electrode 13 is formed on the substrate 11 and the terminal 15 (not shown in Figs. 3A to 3C) is formed on the substrate 11, .

In this formation, first, an Al alloy is formed on the substrate 11. The Al alloy contains 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au. As a film forming method, a sputtering method or a vapor deposition method can be employed. In forming the electrode 13 and the terminal 15, a resist pattern is formed on the Al alloy film. This resist pattern is for masking a portion of the Al alloy film to be processed into the electrode 13 and the terminal 15. Next, using the resist pattern as a mask, the Al alloy film is etched. Thus, the electrode 13 and the terminal 15 can be formed on the substrate 11. [

After the electrode 13 is formed, the surface of the electrode 13 is preferably etched. As a surface treatment method, for example, an inverse sputtering method using an Ar plasma can be employed. It is considered that this surface treatment removes the oxide film formed by the natural oxidation of the surface of the electrode 13 after the formation of the electrode 13.

In manufacturing the piezoelectric element X, next, as shown in Fig. 3B, a piezoelectric film 12 is laminated on the substrate 11. Then, as shown in Fig. Specifically, after the piezoelectric material is formed on the substrate 11 by the sputtering method, the piezoelectric material film is etched using the predetermined resist pattern as a mask to form a piezoelectric film 12 having a predetermined planar shape do. At the time of forming the piezoelectric material according to the sputtering method, the substrate 11 is heated to a predetermined temperature. As a result, the electrode 13 is heated together with the substrate 11, but the hillock is not formed in the electrode 13 or the number and size of the hillock are suppressed. The electrode 13 made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au is difficult to thermally expand to be.

Next, as shown in Fig. 3C, the electrode 14 is formed on the piezoelectric film 12, and a terminal 16 (not shown in Fig. 3C) is formed. In this formation, first, a predetermined conductive material is formed over the surface of the substrate 11 and the surface of the piezoelectric film 12. As a film forming method, a sputtering method or a vapor deposition method can be employed. Next, a resist pattern is formed on the conductive film. This resist pattern is for masking a portion to be processed into the electrode 14 and the terminal 16 in the conductive film. Next, the conductive film is etched using the resist pattern as a mask. Thus, the electrode 14 and the terminal 16 can be formed.

In forming the electrode 14 and the terminal 16, a printing method may be used instead of the above-described method using the sputtering method. In the printing method, first, Ag paste is printed or applied to the surface of the substrate 11 and the surface of the piezoelectric film 12 with a predetermined mask interposed therebetween. Next, after removing the mask, the Ag paste is sintered or annealed to increase the solvent in the paste. In this manner, the electrode 14 and the terminal 16 made of Ag can be formed.

In this way, the piezoelectric element X having high electromechanical conversion efficiency can be produced. In the piezoelectric film forming step described above with reference to Fig. 3B, a piezoelectric material for forming the piezoelectric film 12 is formed while suppressing generation and growth of hillocks in the electrode 13 already formed on the substrate 11 I can do the tabernacle. The reason why high electromechanical conversion efficiency can be obtained in the piezoelectric element X is considered to be that generation and growth of hillocks in the electrode 13 are suppressed at the time of forming the piezoelectric film. When the surface of the electrode 13 is etched after the electrode 13 is formed, it is considered that the surface treatment contributes to suppressing hillock generation and growth at the time of forming the piezoelectric film.

4 and 5 show a piezoelectric element X 'according to a second embodiment of the present invention. The piezoelectric element X 'is provided with a substrate 11, a piezoelectric film 12 and electrodes 23 and 24 so as to excite and receive surface acoustic waves. The piezoelectric element X 'is different from the piezoelectric element X in that the piezoelectric element X' has the electrodes 23 and 24 instead of the electrodes 13 and 14. The substrate 11 and the piezoelectric film 12 are the same as those described in the first embodiment.

The electrodes 23 and 24 constitute an IDT interposed between the substrate 11 and the piezoelectric film 12. The electrodes 23 and 24 are made of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt, And an Al alloy containing 0.1 to 3 wt% of a metal selected from the group. When the Al alloy contains a plurality of metals selected from the group, the content of each additive metal in the Al alloy is in the range of 0.1 to 3 wt%.

The electrode 23 has a comb structure composed of a base portion 23a and a plurality of branch electrodes 23b. The plurality of branch electrodes 23b extend from the base portion 23a and are also parallel to each other. The electrode (23) is continuous with the terminal (25) having a portion exposed to the outside.

The electrode 24 has a comb-like structure composed of a base portion 24a and a plurality of branch electrodes 24b. The plurality of branch electrodes 24b extend from the base portion 24a and are also parallel to each other. The branch electrode 24b is also parallel to the branch electrode 23b. The electrode 24 is continuous with a terminal 26 having a portion exposed to the outside.

The widths d ₂ of the branched electrodes 23 b and 24 b are 20 to 30 μm and the width of the branched electrodes 23 b and 24 b is, for example, 300 to 600 nm. The period (? ₂ ) is, for example, 100 to 150 占 퐉.

6A to 6C show a manufacturing method of the piezoelectric element X '. In manufacturing the piezoelectric element X ', first, as shown in FIG. 6A, an Al alloy film 20' is formed on the substrate 11. The Al alloy contains 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au. As a film forming method, a sputtering method or a vapor deposition method can be employed.

Next, the Al alloy film 20 'is patterned to form electrodes 23 and 24 on the substrate 11 as shown in Fig. 6B, and terminals 25 and 26 (Figs. 6B and 6C) (Not shown in Fig. 6C). Specifically, first, a resist pattern is formed on the Al alloy film 20 '. This resist pattern is for masking a portion of the Al alloy film 20 'to be processed into the electrodes 23 and 24 and the terminals 25 and 26. Next, the Al alloy film 20 'is etched using the resist pattern as a mask. In this manner, the electrodes 23 and 24 and the terminals 25 and 26 can be formed on the substrate 11.

After the electrodes 23 and 24 are formed, the surfaces of the electrodes 23 and 24 are preferably etched. As a surface treatment method, for example, an inverse sputtering method using an Ar plasma can be employed. It is considered that by this treatment, the oxide film generated by the natural oxidation of the surfaces of the electrodes 23 and 24 after the formation of the electrodes 23 and 24 is removed.

In manufacturing the piezoelectric element X ', next, as shown in Fig. 6C, a piezoelectric film 12 is formed on the substrate 11 in a laminated manner. Specifically, after the piezoelectric material is formed on the substrate 11 by the sputtering method, the piezoelectric material film is etched using the predetermined resist pattern as a mask to form a piezoelectric film 12 having a predetermined planar shape do. At the time of forming the piezoelectric material by the sputtering method, the substrate 11 is heated to a predetermined temperature. Accordingly, the electrodes 23 and 24 are heated together with the substrate 11, but the electrodes 23 and 24 do not generate hillock, or even if the hillocks are generated, the number and size thereof are suppressed. The electrodes 23 and 24 made of an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au are hard to thermally expand .

In this way, the piezoelectric element X 'having a high electromechanical conversion efficiency can be manufactured. The piezoelectric film forming process described above with reference to Fig. 6C can be carried out while suppressing generation and growth of hillocks in the electrodes 23 and 24 already formed on the substrate 11, The material can be deposited. The reason why a high electromechanical conversion efficiency can be obtained in the piezoelectric element X 'is considered to be that generation and growth of hillocks in the electrodes 23 and 24 are suppressed at the time of forming the piezoelectric film. When the surfaces of the electrodes 23 and 24 are subjected to the etching treatment after the electrodes 23 and 24 are formed, the surface treatment is effective for suppressing hillock generation and growth at the time of forming the piezoelectric film .

7 and 8 show a touch panel device Y according to a third embodiment of the present invention. The touch panel device Y includes a substrate 31, a piezoelectric film 32 and electrodes 33A to 33D and 34A to 34D and is configured as a SAW type touch panel device. The piezoelectric film 32 is indicated by a phantom line from the viewpoint of clarification of the figure.

The substrate 31 is a transparent substrate having a detection region 31a and a peripheral region 31b as a medium through which a surface acoustic wave propagates. The boundary between the detection region 31a and the peripheral region 31b is indicated by a dotted line. The substrate 31 is, for example, a non-piezoelectric substrate such as a transparent glass substrate and has a thickness of, for example, 0.7 to 1.1 mm. The detection area 31a is a detection subject area in the touch panel device Y and is rectangular in the present embodiment. The peripheral region 31b surrounds the detection region 31a and is an area provided with an exciting means and a receiving means described later of the touch panel device Y. [

The piezoelectric film 32 is formed in the peripheral region 31b of the substrate 31 and is made of a piezoelectric material exhibiting a piezoelectric effect and an opposite piezoelectric effect similarly to the piezoelectric film 12 in the first embodiment. The thickness h of the piezoelectric film 32 is, for example, 1.0 to 3.0 占 퐉.

Electrodes 33A to 33D are interposed between the substrate 31 and the piezoelectric film 32 and are made of a material selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, And an Al alloy containing 0.1 to 3 wt% of metal. The thickness of the electrodes 33A to 33D is, for example, 300 to 600 nm. The corresponding terminals 35A to 35D are connected to the electrodes 33A to 33D, respectively. Each of the terminals 35A to 35D has a portion exposed to the outside.

The electrodes 34A to 34D are formed on the piezoelectric film 32 and each have a comb structure composed of a base portion 34a and a plurality of branch electrodes 34b. The plurality of branch electrodes 34b belonging to the same electrode extend from the same base portion 34a and are also parallel to each other.

In this embodiment, the plurality of branch electrodes 34b parallel to each other have the inner portion 34b 'relatively closer to the detection region 31a and the outer portion 34b' farther from the detection region 31a The branch electrode 34b is bent at a predetermined angle. The bending angle is determined by the ratio of the adjacent sides defining the rectangular detection region 31a. For example, when the detection region 31a is square, that is, when the ratio of the adjacent sides is 1: 1, the bending angle is 45. Further, the branch electrode 34b is connected to the electrodes 33A 33D).

The thickness of the electrode 34 is, for example, 300 to 600 nm, and the width d ₃ (shown in FIG. 8) of each branch electrode 34b is, for example, 40 to 60 μm. The electrode period (λ ₃₎ of the inner portion (34b ') of the branch electrode (34b) (Fig. Are shown in 8) and outer part (34b ") electrode period (λ ₄₎ (is shown in Fig. 8) of the electrode of the above-described The electrode period? ₃ and the electrode period? ₄ in the single electrode are the same as the period (? ₁ ) in accordance with the driving method of the touch panel device Y, The electrode period? ₃ and / or the electrode period? ₄ between the electrodes 34A to 34D are set to be equal to each other in accordance with the driving method of the touch panel device Y It is preferable that the thickness h of the piezoelectric film 32 and the electrode period? ₃ have a relationship of 0.005? H /? ₃ ? 0.1. Likewise, the thickness h of the piezoelectric film 32 It is preferable that the thickness h and the electrode period? _{4 have} a relationship of 0.005? H /? ₄ ? 0.1.

The electrodes 34A to 34D are made of a predetermined conductive material. As the constituent material of the electrodes 34A to 34D, the same materials as those of the electrodes 33A to 33D may be employed. Further, corresponding terminals 36A to 36D are connected to the electrodes 34A to 34D, respectively.

The touch panel device Y is provided with four piezoelectric elements X (piezoelectric elements XA to XD) according to the first embodiment in the peripheral region 31b of the substrate 31. [ Specifically, the electrode pairs 33A and 34A, the pair of electrodes 33B and 34B, the pair of electrodes 33C and 34C, and the pair of electrodes 33D and 34D are connected to the pair of electrodes 13 and 14 of the piezoelectric element X , And the piezoelectric film 32 sandwiched between each pair of electrodes includes four piezoelectric films 12 of four piezoelectric elements X and the substrate 31 for supporting the four piezoelectric films 12 has four And four substrates 11 of the piezoelectric element X. [ The terminals 35A to 35D and the terminals 36A to 36D correspond to the terminal 15 and the terminal 16 of the piezoelectric element X, respectively. The touch panel device Y including the four piezoelectric elements X can be manufactured using the manufacturing method of the piezoelectric element X described above with reference to Figs. 3A to 3C.

In operation of the touch panel device Y, for example, two piezoelectric elements XA and XC facing each other are excited and driven at different timings intermittently.

The piezoelectric element XA is excited and driven by applying an alternating voltage between the electrodes 33A and 34A through the terminals 35A and 36A. During excitation operation, two kinds of surface acoustic waves (SAW) f1 and f2 of a predetermined frequency are excited by the piezoelectric element XA. The SAW (f1) is excited to propagate in a direction orthogonal to the inner side portion 34b 'of the branch electrode 34b in the piezoelectric element XA. The SAW (f2) is excited to propagate in a direction orthogonal to the outer side portion 34b "of the branch electrode 34b.

The SAW f1 propagates through the detection region 31a of the substrate 31 and is received at the plurality of inner portions 34b 'in the piezoelectric element XD. As a result, a reception signal is outputted from the piezoelectric element XD through the terminals 35D and 36D. This reception signal is substantially the same as the reception signal in which the inner portion 34b 'at the upper end in the figure of the piezoelectric element XD receives the SAW (f1) and the inner portion 34b' Until it is output.

The SAW f2 propagates through the detection region 31a of the substrate 31 and is received at the plurality of outer side portions 34b "in the piezoelectric element XB. As a result, 35B, and 36B after the SAW (f2) is received by the upper side outer portion 34b " in the figure of the piezoelectric element XB, Until the outer portion 34b " receives the SAW (f2).

On the other hand, the piezoelectric element XC is excited and driven by applying an alternating voltage between the electrodes 33C and 34C through the terminals 35C and 36C. During excitation operation, two types of SAW (f3, f4) of a predetermined frequency are excited by the piezoelectric element XC. The SAW f3 is excited to propagate in a direction orthogonal to the inner portion 34b 'of the branch electrode 34b in the piezoelectric element XC. The SAW f4 is excited to propagate in a direction orthogonal to the outer side portion 34b "of the branching electrode 34b. Such excitation drive of the piezoelectric element XC is performed, for example, from the piezoelectric elements XB and XD Is performed immediately after the above-described reception signal output of the first embodiment is completed.

The SAW f3 propagates through the detection region 31a of the substrate 31 and is received at the plurality of inner portions 34b 'in the piezoelectric element XB. As a result, a reception signal is outputted from the piezoelectric element XB through the terminals 35B and 36B. This reception signal is substantially the same as the reception signal when the inner portion 34b 'at the lower end in the figure of the piezoelectric element XB receives the SAW (f3) and the inner portion 34b' Until it is output.

The SAW f4 propagates through the detection region 31a of the substrate 31 and is received at the plurality of outer portions 34b "in the piezoelectric element XD. As a result, 35D and 36D of the piezoelectric element XD substantially after the SAW (f4) is received by the outer portion 34b "at the lower end of the figure in the piezoelectric element XD, Until the outer portion 34b "receives the SAW (f4).

In operation of the touch panel device Y, reception from the piezoelectric elements XB and XD based on the reception of the SAWs f3 and f4 from the excitation of the SAWs f1 and f2 by the piezoelectric element XA The series of operations up to the output of the signal, as described above, is repeated.

If the finger or the like is in contact with any one of the detection areas 31a of the substrate 31 during operation of the touch panel device Y, the amplitudes of the SAW (f1 to f4) In this case, it is attenuated at the position. The output level of the reception signal output from the piezoelectric elements XB and XD decreases based on the SAW attenuated by the amplitude. Therefore, by detecting and analyzing when the output level of the reception signal decreases, The contact position is detected in a specific manner.

The piezoelectric elements XB and XD are used in place of the piezoelectric elements XA and XC as excitation means and the piezoelectric elements XB and XD are used as receiving means in place of the piezoelectric elements XB and XD, (XA, XC) may be used.

The touch panel device Y is provided with the piezoelectric elements X (piezoelectric elements XA to XD) of the first embodiment having high electromechanical conversion efficiency as excitation means and receiving means. Such a touch panel device Y is very suitable for reducing the driving voltage and improving the detection precision.

9 and 10 show a touch panel device Y 'according to a fourth embodiment of the present invention. The touch panel device Y 'includes a substrate 31, a piezoelectric film 32 and electrodes 43A to 43D and 44A to 44D, and is configured as a SAW touch panel device. The touch panel device Y 'is different from the touch panel device Y in that it has electrodes 43A to 43D and 44A to 44D instead of the electrodes 33A to 33D and 34A to 34D. The substrate 31 and the piezoelectric film 32 are the same as those described in the third embodiment.

The electrode pairs 43A and 44A, the electrode pairs 43B and 44B, the electrode pairs 43C and 44C and the electrode pairs 43D and 44D are formed by stacking an IDT interposed between the substrate 31 and the piezoelectric film 32 And an Al alloy containing 0.1 to 3 wt% of a metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au.

The electrodes 43A to 43D each have a comb-like structure composed of a base portion 43a and a plurality of branch electrodes 43b. The plurality of branch electrodes 43b belonging to the same electrode extend from the same base portion 43a and are also parallel to each other. In this embodiment, the plurality of branch electrodes 43b parallel to each other have an inner portion 43b 'relatively closer to the detection region 31a and an outer portion 43b' farther from the detection region 31a The corresponding electrodes 45A to 45D are connected to the electrodes 43A to 43D so as to be continuous with the electrodes 43A to 43D, Each of the terminals 45A to 45D has a portion exposed to the outside.

Each of the electrodes 44A to 44D has a comb structure including a base portion 44a and a plurality of branch electrodes 44b. The plurality of branch electrodes 44b belonging to the same electrode extend from the same base portion 44a and are also parallel to each other. The branch electrode 44b is also parallel to the branch electrode 43b. In this embodiment, the plurality of branch electrodes 44b parallel to each other have the inner portion 44b 'and the outer portion 44b', which extend in different predetermined directions, that is, the branch electrodes 44b The bending angle of the branching electrodes 43b and 44b is determined by the ratio of the adjacent sides defining the rectangular detection area 31a. Respectively correspond to the terminals 46A to 46D. The terminals 46A to 46D each have a portion exposed to the outside.

The thickness of the electrodes 43 and 44 is, for example, 300 to 600 nm, and the width d ₄ of each of the branch electrodes 43b and 44b is, for example, 20 to 30 μm. Like the inside part of the cycle electrode (43b ', 44b') ( λ 5) and the outer electrode cycle of the sides (43b ", 44b") ( λ 6) , the cycle above-described electrodes (λ _2), for example 100~ 150 mu m.

The touch panel device Y 'includes four piezoelectric elements X' (piezoelectric elements XA 'to XD') according to the second embodiment in the peripheral region 31b of the substrate 31. [ Specifically, the electrode pairs 43A and 44A, the electrode pairs 43B and 44B, the electrode pairs 43C and 44C, and the electrode pairs 43D and 44D are connected to the electrode pairs 23 of the piezoelectric elements X ' , And the piezoelectric film 32 sandwiched between the pair of electrodes includes four piezoelectric films 12 of four piezoelectric elements X 'and the substrate 31 supporting these piezoelectric films 32 And four substrates 11 of the piezoelectric elements X '. The terminals 45A to 45D and the terminals 46A to 46D correspond to the terminal 25 and the terminal 26 of the piezoelectric element X ', respectively. The touch panel device Y 'including the four piezoelectric elements X' can be manufactured by the manufacturing method of the piezoelectric element X 'described above with reference to FIGS. 6A to 6C.

In operation of the touch panel device Y ', for example, two piezoelectric elements XA' and XC 'opposed to each other are excited and driven at different timings intermittently.

The piezoelectric element XA 'is excited and driven by applying an AC voltage between the electrodes 43A and 44A through the terminals 45A and 46A. During excitation operation, two types of surface acoustic wave (SAW) f5 and f6 of a predetermined frequency are excited by the piezoelectric element XA '. The SAW (f5) is excited to propagate in a direction orthogonal to the inner portions 43b 'and 44b' in the piezoelectric element XA '. The SAW (f6) is excited to propagate in a direction perpendicular to the outer portions 43b ", 44b "in the piezoelectric element XA '.

The SAW f5 propagates through the detection region 31a of the substrate 31 and is received at the plurality of inner portions 43b 'and 44b' in the piezoelectric element XD '. As a result, a reception signal is outputted from the piezoelectric element XD 'through the terminals 45D and 46D. This reception signal is substantially the same as that in the figure after the SAW (f5) is received by the upper inner side portion 43b '(44b') of the piezoelectric element XD ' ) Is received until SAW (f5) is received.

The SAW f6 propagates through the detection region 31a of the substrate 31 and is then received at the plurality of outer portions 43b ", 44b "in the piezoelectric element XB '. As a result, a reception signal is output from the piezoelectric element XB 'through the terminals 45B and 46B. This reception signal is substantially the same as that in the figure when the outer side portion 43b "44b" in the upper side of the figure in the figure receives the SAW (f6) ) Is received until SAW (f6) is received.

On the other hand, the piezoelectric element XC 'is excited and driven by applying an AC voltage between the electrodes 43C and 44C through the terminals 45C and 46C. During excitation operation, two types of SAW (f7, f8) of a predetermined frequency are excited by the piezoelectric element XC '. The SAW (f7) is excited to propagate in a direction orthogonal to the inner portions 43b 'and 44b' in the piezoelectric element XC '. The SAW f8 is excited to propagate in a direction orthogonal to the outer portions 43b ", 44b "in the piezoelectric element XC '. Such excitation drive of the piezoelectric element XC 'is performed, for example, immediately after the above-described reception signal output from the piezoelectric elements XB' and XD 'is completed.

The SAW f7 propagates through the detection region 31a of the substrate 31 and is received at the plurality of inner portions 43b 'and 44b' of the piezoelectric element XB '. As a result, a reception signal is output from the piezoelectric element XB 'through the terminals 45B and 46B. This reception signal is substantially the same as that in the figure after the SAW (f7) is received by the inner portion 43b '(44b') at the lower end of the figure in the figure, ) Is received until SAW (f7) is received.

The SAW f8 propagates through the detection region 31a of the substrate 31 and is received at the plurality of outer portions 43b ", 44b "in the piezoelectric element XD '. As a result, a reception signal is outputted from the piezoelectric element XD 'through the terminals 45D and 46D. This reception signal is substantially the same as that of the upper part 43b "44b" in the figure after receiving the SAW (f8) by the outer side portion 43b "44b" ) Is received until SAW (f8) is received.

In operation of the touch panel device Y ', the piezoelectric elements XB' and XD 'based on the reception of the SAWs f7 and f8 from the excitation of the SAWs f5 and f6 by the piezoelectric element XA' ) To the output of the reception signal from the input terminal is repeated.

If the finger or the like is in contact with any one of the detection areas 31a of the substrate 31 during operation of the touch panel device Y ', the amplitudes of the SAWs f5 to f8 pass through the position It is attenuated at that position. The output level of the reception signal output from the piezoelectric elements XB 'and XD' is reduced based on the SAW whose amplitude is attenuated. Therefore, when the output level of the reception signal output from the piezoelectric elements XB 'and XD' The contact position in the detection region 31a is specified or detected.

In order to operate the touch panel device Y ', piezoelectric elements XB' and XD 'are used as excitation means in place of piezoelectric elements XA' and XC 'and piezoelectric elements XB' and XD ' 'May be used instead of the piezoelectric elements XA' and XC '.

The touch panel device Y 'is provided with the piezoelectric element X' (piezoelectric elements XA 'to XD') of the second embodiment having high electromechanical conversion efficiency as the excitation means and the reception means. The touch panel device Y 'is very suitable for reducing the driving voltage and improving the detection precision.

As a method of operating the touch panel devices (Y, Y '), other forms may be employed. For example, a method described in Japanese Patent Application Laid-Open No. 2002-222041 for operating the touch panel device according to the first to third embodiments can be employed.

[First Embodiment]

A regular opposed filter composed of two piezoelectric elements X as shown in Fig. 11 was produced. Each of the piezoelectric elements X of this embodiment constituting this filter is according to the first embodiment. In the fabrication of the filter, first, an Al alloy film containing 1.0 wt% of Cu was formed on the glass substrate 11 by sputtering in the first film forming step to form an Al alloy film with a thickness of 300 nm. In this sputtering, an Al alloy target containing 1.0 wt% of Cu was used.

Next, the Al alloy film was etched using the predetermined resist pattern as a mask to pattern the Al alloy film. In this manner, the electrode 13 and the terminal 15 were formed on the substrate 11. Then, the surface of the electrode 13 was etched by reverse sputtering using Ar plasma.

Next, in the second film forming step, ZnO was formed on the substrate 11 by a sputtering method to form a piezoelectric material film having a thickness of 2 m. Specifically, ZnO was formed on a substrate by reactive sputtering using a ZnO sintered body target and using Ar gas and O ₂ gas as sputter gas. In this sputtering, the flow ratio of Ar gas and O ₂ gas was 4: 1. Then, the piezoelectric material film was etched by using a predetermined resist pattern as a mask to pattern the piezoelectric material film. Thus, the piezoelectric film 12 was formed.

Next, in the third film forming step, an Al alloy film was formed by sputtering over the surface of the substrate 11 and the surface of the piezoelectric film 12 to form an Al alloy film with a thickness of 300 nm. In this sputtering, the same Cu-containing Al alloy target used for forming the above-described electrode 13 was used. Next, the Al alloy film was etched using the predetermined resist pattern as a mask to pattern the Al alloy film. Thus, the electrode 14 and the terminal 16 having the base portion 14a and the plurality of parallel branch electrodes 14b were formed. In the electrode 14 of the present embodiment, the width d ₁ of the branch electrode 14b is 44 μm and the electrode period λ ₁ of the branch electrode 14b is 110 μm.

By the above method, a plurality of filters according to the present embodiment were manufactured. The thickness h of the piezoelectric film 12 is 2 占 퐉 and the electrode period? 1 of the branch electrode 14b satisfies the condition of 0.005? H /? ₁ ? 0.1 do.

[Second Embodiment]

In the first film forming step, in the same manner as in the first embodiment, except that an Al alloy containing Cu in an amount of 0.5 wt% was used instead of the Al alloy containing 1.0 wt% of Cu Were fabricated. In the filter of this embodiment, the electrode 13 is made of an Al alloy containing 0.5 wt% of Cu. The thickness h of the piezoelectric film 12 is 2 占 퐉 and the electrode period? ₁ of the branch electrode 14b is 0.005? H /? ₁ ≪ / = 0.1.

[Third Embodiment]

In the same manner as in Example 1, except that an Al alloy containing Cu in an amount of 2.0 wt% was used instead of the Al alloy containing 1.0 wt% Cu in the first film forming step Were fabricated. In the filter of this embodiment, the electrode 13 is made of an Al alloy containing 2.0 wt% Cu. The thickness h of the piezoelectric film 12 is 2 占 퐉 and the electrode period? ₁ of the branch electrode 14b is 0.005? H /? ₁ ≪ / = 0.1.

[Comparative Example]

In the first film forming step, a plurality of filters according to this comparative example were fabricated in the same manner as in Example 1 except that pure Al was deposited in place of the Al alloy containing 1.0 wt% Cu. In the filter of this comparative example, the electrode interposed between the substrate and the piezoelectric film is pure Al.

[Fourth Embodiment]

A filter having the same structure as that of the first embodiment was fabricated except that the piezoelectric film 12 was made of ZnO doped with Mn instead of ZnO. In the sputtering in the second film forming step in the production of this filter, a ZnO sintered target containing Mn ₂ O ₃ of a predetermined concentration was used.

[Measurement of insertion loss]

For each of the filters of the first to third embodiments and the comparative example, the insertion loss between the input signal and the received signal was measured. The results are shown in the graph of Fig. In the graph of Fig. 12, the abscissa represents the resistance (k [Omega]) between the opposing electrode pairs via the piezoelectric film, and the ordinate represents the insertion loss (dB).

It can be seen from the graph of Fig. 12 that the insertion loss of the filters of the first to third embodiments is smaller than that of the filter of the comparative example. This is considered to be because, when the electrode interposed between the substrate and the piezoelectric film is made of an Al alloy containing Cu at a predetermined concentration, the electromechanical conversion efficiency in the piezoelectric element is higher than in the case where the electrode is made of pure Al . Also, as shown in the graph of Fig. 12, there is a variation in the value of the interelectrode resistance among a plurality of filters according to the same embodiment, but between the plurality of filters according to the same embodiment, Is a small tendency.

For the filters of the first and fourth embodiments, the annealing time dependence of the insertion loss was examined. Specifically, the respective filters of the first and fourth embodiments were subjected to annealing at 250 ° C for 1 hour and annealing at 250 ° C for 1 hour, that is, for a total of 2 hours After the annealing treatment, the insertion loss was measured. The results are shown in the graph of Fig. In the graph of Fig. 13, the abscissa axis represents the annealing time (h) and the ordinate axis represents the insertion loss (dB). The measurement result of the film of the first embodiment is indicated by a line E1, and the measurement result of the film of the fourth embodiment is indicated by a line E4.

It can be seen from the graph of Fig. 13 that when the piezoelectric element undergoes a predetermined annealing treatment, the ZnO piezoelectric film doped with Mn is more suitable for reducing the insertion loss than the ZnO piezoelectric film not doped. This is considered to be because diffusion of Al, which is an electrode constituting material, into the piezoelectric film is suppressed when Mn is doped into ZnO as the piezoelectric material. In the case where the electrodes on the piezoelectric film are formed by a printing method, an annealing process for sintering the conductive paste printed in a predetermined pattern is performed. Therefore, the structure in which the piezoelectric film is formed of ZnO doped with Mn has a particularly advantageous effect when the electrode on the piezoelectric film is formed by a printing method.

Claims (19)

A substrate, a piezoelectric film, a first electrode, and a second electrode, Wherein at least one of the first electrode and the second electrode is formed of a material selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt, and Au interposed between the substrate and the piezoelectric film And 0.1 to 3 wt% of one metal selected from the group consisting of Al, At least one of the first electrode and the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, The thickness of the piezoelectric film is h, and the electrode period (period) of the plurality of branch electrodes is?, The? Value is 100 to 150 占 퐉, and the h /? Value is 0.005 to 0.1. The method according to claim 1, Wherein the first electrode is interposed between the substrate and the piezoelectric film, and the second electrode is formed on the piezoelectric film. 3. The method of claim 2, Wherein the first electrode has a portion opposed to the plurality of branch electrodes via the piezoelectric film. delete The method according to claim 1, Wherein the first electrode and the second electrode are interposed between the substrate and the piezoelectric film to constitute an interdigital transducer. The method according to claim 1, Wherein the piezoelectric film is made of ZnO doped with Mn. A first electrode made of an Al alloy containing 0.1 to 3 wt% of one metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, And, A step of removing an oxide film on a surface of the first electrode; A step of forming a piezoelectric film overlapping the first electrode on the substrate; A step of forming a second electrode on the piezoelectric film And a piezoelectric element. A first electrode made of an Al alloy containing 0.1 to 3 wt% of one metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, And, Etching the surface of the first electrode; A step of forming a piezoelectric film overlapping the first electrode on the substrate; A step of forming a second electrode on the piezoelectric film And a piezoelectric element. 9. The method of claim 8, Wherein the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, and the first electrode is provided on a portion opposed to the plurality of branch electrodes across the piezoelectric film Wherein the piezoelectric element is a piezoelectric element. 9. The method of claim 8, Wherein the piezoelectric film is made of ZnO doped with Mn. An interdigital transducer composed of an Al alloy containing 0.1 to 3 wt% of one metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au ; A step of removing an oxide film on a surface of the interdigital transducer; A step of forming a piezoelectric film overlapping the interdigital transducer on the substrate And a piezoelectric element. An interdigital transducer composed of an Al alloy containing 0.1 to 3 wt% of one metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au ; A step of etching the surface of the interdigital transducer; A step of forming a piezoelectric film overlapping the interdigital transducer on the substrate And a piezoelectric element. 13. The method of claim 12, Wherein the piezoelectric film is made of ZnO doped with Mn. A substrate including a detection region and a peripheral region surrounding the detection region, Excitation means formed in the peripheral region for exciting surface acoustic waves in the substrate, Receiving means formed in the peripheral region for receiving a surface acoustic wave propagated in the detection region, / RTI > Wherein at least one of the exciting means and the receiving means includes a piezoelectric film, a first electrode, and a second electrode, and at least one of the first electrode and the second electrode is interposed between the substrate and the piezoelectric film And an Al alloy containing 0.1 to 3 wt% of one metal selected from the group consisting of Ti, Cr, Ni, Cu, Zn, Pd, Ag, Hf, W, Pt and Au, At least one of the first electrode and the second electrode has a base portion and a plurality of branch electrodes extending from the base portion and parallel to each other, The thickness of the piezoelectric film is h, and the electrode period of the plurality of branch electrodes is?, The? Is 100 to 150 占 퐉 and the h /? Value is 0.005 to 0.1. 15. The method of claim 14, Wherein the first electrode is interposed between the substrate and the piezoelectric film, and the second electrode is formed on the piezoelectric film. 16. The method of claim 15, Wherein the first electrode has a portion opposed to the plurality of branch electrodes via the piezoelectric film. delete 15. The method of claim 14, Wherein the first electrode and the second electrode are interposed between the substrate and the piezoelectric film to constitute an interdigital transducer. 15. The method of claim 14, Wherein the piezoelectric film is made of ZnO doped with Mn.

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