Element, electronic device, electronic apparatus, and system

Abstract

To provide an element that is friendly to the environment and has excellent accuracy.SOLUTION: A piezoelectric element is manufactured by: laminating a compound film containing Hf, as a first intermediate film, on a crystal substrate; next, laminating a metal film containing metal which is to be transformed into martensite by heat treatment or processing, as a second intermediate film, laminating a piezoelectric film directly or through another layer, by crystal growth; peeling the crystal substrate; winding an obtained piezoelectric material around an approximately circular base; and providing reflectors and interdigital electrodes in order from a joint part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an element, an electronic device, an electronic apparatus, and a system. [Background technology]

[0002] A surface acoustic wave (SAW) element, which is a type of piezoelectric element, is equipped with an interdigital transducer (IDT) on a piezoelectric substrate such as a quartz substrate. The interdigital transducer is formed in pairs on the piezoelectric substrate so that the comb-shaped electrodes face each other without contact. By applying an AC voltage to the interdigital transducer, the piezoelectric effect and inverse piezoelectric effect of the piezoelectric substrate can vibrate the surface or near the surface of the piezoelectric substrate on which the interdigital transducer is formed in a frequency band. Depending on the combination and configuration of the interdigital transducers, surface acoustic wave elements are widely used in electronic circuits that make up various electronic devices such as oscillators, bandpass filters, and gyros.

[0003] In recent years, for example, as mobile terminal devices used in mobile communications become smaller and lighter, there is a demand for surface acoustic wave elements with higher accuracy to achieve high communication quality, and in order to meet such demands, spherical SAW sensors (ball SAW sensors) and the like have been considered (Patent Document 1). Ball SAW sensors are useful for achieving high sensitivity because they can increase the interaction distance significantly compared to planar sensors by utilizing the phenomenon in which the natural collimated beam of SAW makes multiple rounds. However, there are problems with costs, such as a complicated manufacturing process, and SAW devices have many issues with high-frequency characteristics, etc., and are still not satisfactory. Furthermore, with the demand for energy saving to address environmental issues, etc., a new SAW element that can solve these problems has been eagerly awaited. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2015-154015 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an element, an electronic device, an electronic equipment and a system which are environmentally friendly and have excellent precision. [Means for solving the problem]

[0006] As a result of intensive research into achieving the above-mentioned object, the inventors have succeeded in creating a laminated structure in which piezoelectric bodies are laminated on a metal film with the piezoelectric bodies oriented in the same crystal axis direction. They have discovered that such a laminated structure can easily realize an element in which one or more interdigital electrodes are provided on a piezoelectric body, and the piezoelectric body is in sheet form, and have found that such an element can solve the above-mentioned conventional problems in one fell swoop. After obtaining the above findings, the present inventors conducted further studies and completed the present invention.

[0007] That is, the present invention relates to the following inventions. [1] An element comprising one or more interdigital transducers provided on a piezoelectric body, the piezoelectric body being in the form of a sheet. [2] The element according to [1], wherein the piezoelectric body is bonded to a substrate. [3] The element according to [2], wherein the base is cylindrical, approximately cylindrical, barrel-shaped or approximately barrel-shaped, the piezoelectric body is wound around the base to form a circle or approximately circle, and the interdigital electrodes are arranged so that surface acoustic waves can propagate in the circumferential direction or approximately circumferential direction of the circle or approximately circle. [4] The element according to [3], wherein a reflector is provided in a propagation path of the surface acoustic wave. [5] The element according to [4], wherein two or more of the reflectors are provided, and the joints between the piezoelectric bodies formed by the winding are provided between the reflectors. [6] The element according to any one of [3] to [5], wherein the interdigital transducer comprises a SAW generating means for generating the surface acoustic wave and a SAW receiving means for receiving the surface acoustic wave. [7] The element according to any one of [1] to [6], wherein the piezoelectric body is formed on a metal film. [8] The element according to [7], wherein the piezoelectric body and the metal film are each oriented in a (100) direction. [9] The element according to [7] or [8] above, wherein the metal film comprises two or more types of metal layers.

[10] The element according to any one of [7] to [9], wherein the metal film contains a metal that undergoes martensitic transformation upon heat treatment or processing, and the piezoelectric body and the metal film are each oriented in approximately the same crystal axis direction.

[11] The element according to

[10] , wherein the metal film contains Fe.

[12] The element according to

[10] or

[11] , wherein the metal film contains Cr.

[13] The element according to any one of [1] to

[12] , wherein the piezoelectric body is made of a single crystal film.

[14] An electronic device, an electronic equipment, or a system including an element, the element being the element according to any one of [1] to

[13] above. Effect of the Invention

[0008] The element, electronic device, electronic equipment and system of the present invention have the advantages of being environmentally friendly and having excellent precision. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of an example of a preferred embodiment of the element of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating an example of a reflector that can be suitably used in the element of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating an example of another preferred embodiment of the element of the present invention. [Figure 4]2 is a diagram for explaining the propagation direction of a surface acoustic wave in the element of the present invention. FIG. [Diagram 5] FIG. 1 is a diagram showing a schematic diagram of an example of a preferred embodiment of a laminated structure of the present invention. [Figure 6] FIG. 2 is a diagram showing XRD diffraction patterns in the examples. [Figure 7] FIG. 2 is a diagram illustrating a test piece of an embodiment product in a test example. [Figure 8] FIG. 2 is a diagram illustrating a test piece of a comparative example in a test example. [Figure 9] FIG. 13 is a diagram showing bending strength test results in a test example. [Figure 10] FIG. 2 is a schematic diagram showing a film forming apparatus preferably used in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The element of the present invention is not particularly limited as long as it is an element in which one or more interdigital electrodes are provided on a sheet-shaped piezoelectric body. In the present invention, it is preferable that the piezoelectric body is bonded to a base. The bonding may be performed by a known bonding means, and in the present invention, it is preferable that the bonding means is a metal bonding means or a bonding means. The metal bonding means may be a known metal bonding means, and a metal film may be bonded to the piezoelectric body, but in the present invention, it is preferable that the piezoelectric body is formed on the metal film and the resulting laminated structure is used. In the present invention, it is preferable that the piezoelectric body is formed on a metal film, and it is more preferable that the piezoelectric body and the metal film are each oriented in the (100) direction. In the present invention, it is preferable that the metal film is made of two or more metal layers, and one of them contains a metal that undergoes martensitic transformation by heat treatment or processing, and it is more preferable that the piezoelectric body and the metal film are each oriented in approximately the same crystal axis direction. According to such a preferable range, the precision of the element can be improved. In addition, it is preferable that the metal film contains Fe, and more preferably contains Cr. In accordance with such a preferred range, the piezoelectric body has excellent flexibility, and in an element involving bending of the piezoelectric body, excellent precision can be more easily achieved. The piezoelectric body is preferably made of a single crystal film. The bonding means is not particularly limited, but a suitable example is a means using a known adhesive.

[0011] In the present invention, it is preferable that the base is cylindrical, approximately cylindrical, barrel-shaped or approximately barrel-shaped, the piezoelectric body is wound around the base to form a circle or approximately circle, and the interdigital transducer is disposed so that the surface acoustic wave can propagate in the circumferential direction or approximately circumferential direction of the circle or approximately circle. According to such a preferable range, the accuracy of the element as a SAW device can be improved even without using a ball SAW or the like. According to the present invention, it is preferable that a reflector is provided in the propagation path of the surface acoustic wave, and more preferable that two or more reflectors are provided, and the joint between the piezoelectric bodies by the winding is provided between the reflectors. According to such a preferable range, the manufacturing process of the element can be significantly simplified and the versatility can be improved. According to the present invention, it is preferable that the interdigital transducer includes a SAW generating means for generating the surface acoustic wave and a SAW receiving means for receiving the surface acoustic wave. According to such a preferable range, the accuracy of the element can be improved more easily regardless of the shape of the base.

[0012] The element preferably includes a circular or approximately circular piezoelectric body, and one or more interdigital transducers are provided on the piezoelectric body so that surface acoustic waves can propagate in the circumferential or approximately circumferential direction. In the present invention, however, it is more preferable that a reflector is provided on the piezoelectric body within the propagation path of the surface acoustic waves.

[0013] The reflector is not particularly limited as long as it is provided on the piezoelectric body within the propagation path of the surface acoustic wave (hereinafter also referred to as "SAW"), and may be a known reflector, but in the present invention, it is preferable that the reflector is located adjacent to an interdigital transducer (hereinafter also referred to as "IDT electrode") in the propagation direction of the SAW, for example, as shown in Fig. 1. The reflector may be, for example, an electrode formed in a lattice shape, and in the present invention, it is preferable that the reflector has a pair of mutually opposing reflection bus bars 11 and a plurality of reflection electrode fingers 13 extending between the pair of reflection bus bars 11, as shown in Fig. 2.

[0014] The shape and dimensions of the reflective busbar 11 and the reflective electrode fingers 13 in FIG. 2 may be basically the same as those of the busbar and electrode fingers of the IDT electrode, except that both ends of each reflective electrode finger 13 are connected to a pair of reflective busbars 11. For example, each reflective electrode finger 13 has an elongated shape that extends linearly in a direction (direction D2) perpendicular to the propagation direction of the SAW with a certain width, and has the same length as each other. For example, the multiple reflective electrode fingers 13 are arranged side by side in the propagation direction of the SAW. The number of the multiple reflective electrode fingers 13 is usually set so that the reflectance of the SAW in the mode intended to be used is approximately 100% or more. A theoretically necessary minimum number is, for example, several to about 10, and the number of the reflective electrode fingers 13 is preferably 20 or more.

[0015] The reflector is usually not electrically connected to the IDT electrode, and may be in an electrically floating state (a state in which no potential is applied from the outside), or may be applied with a reference potential, etc. In the present invention, the reflector may be electrically connected to one electrode portion of the IDT electrode, but is preferably in an electrically floating state (a state in which no potential is applied from the outside).

[0016] In the present invention, it is preferable that the element has a SAW generating means for generating the surface acoustic waves and a SAW receiving means for receiving the surface acoustic waves, and it is more preferable that a total of two or more interdigital transducers are provided on either side of the joint between the two reflectors and the piezoelectric body, as shown in Fig. 3. With this configuration, it is possible to further improve the accuracy of correction using the signal, and it is possible to more easily realize a sensor with higher sensitivity.

[0017] Here, a preferred example of the correction using the SAW receiving means 19 in Fig. 3 is shown. As shown in Fig. 4, when a voltage is applied to the interdigital transducer 13, the voltage is applied to the piezoelectric body 12 by the electrode fingers of the interdigital transducer, and a SAW of a predetermined mode is excited which propagates along the piezoelectric body 12 in the D1 and D2 directions. The excited SAW is mechanically reflected by the electrode fingers of the interdigital transducer 13 and the reflector 20, and a standing wave is formed with the pitch of the electrode fingers as a half wavelength. The standing wave is converted into an electric signal of the same frequency as the standing wave, and is extracted by the electrode fingers of the interdigital transducer. Here, a phase difference occurs between the waves in the D1 direction and the waves in the D2 direction propagating in the SAW to which the rotational angular velocity has been applied, and therefore, for example, correction can be made using the following formula (1) which expresses the phase difference.

number

[0018] The element can be easily manufactured using the laminated structure. In the present invention, when the laminated structure includes a crystal substrate, it is preferable to peel off the crystal substrate before use. The laminated structure is a flexible laminated structure having at least a second layer laminated on a first layer, and the first layer is preferably made of a metal film, and the second layer is preferably made of a piezoelectric film (hereinafter also referred to as a "piezoelectric layer") made of the piezoelectric material. Such a laminated structure can exhibit superior piezoelectric characteristics at high frequencies and the like.

[0019] In the present invention, it is preferable that the piezoelectric film and the metal film are each oriented in the (100) direction. In addition, in the present invention, it is preferable that the piezoelectric film is a single crystal film, since it has better piezoelectric properties and durability. In addition, in the present invention, it is preferable that the piezoelectric film is a PTO film or a PZT film. In addition, in the present invention, it is preferable that the metal contains Fe, and more preferably further contains Cr. According to such a preferable range, better crystal growth can be realized, and a crystal film of higher quality can be obtained. In addition, in the present invention, it is preferable that a conductive oxide film is between the metal film and the piezoelectric film, and that the metal film is laminated on a conductive nitride film. In addition, when the conductive oxide film is laminated, it is preferable that the conductive oxide film contains Sr and / or Ru, and when the conductive nitride film is laminated, it is preferable that the conductive nitride film contains Hf.

[0020] The metal film is not particularly limited as long as it contains a metal as a main component. The term "main component" refers to a ratio in which the atomic ratio of the metal in the metal film is 0.5 or more. In the present invention, the atomic ratio of the metal to all metal elements in the metal film is preferably 0.7 or more, and more preferably 0.8 or more. The metal is preferably a metal that undergoes martensitic transformation by heat treatment or processing, but is not particularly limited and may be a known metal. Examples of the metal that undergoes martensitic transformation include Fe-Cr-Ni, Fe, Fe-Cr-Ni-Cu-Nb, Fe-Ni, Fe-Ni-Co, Fe-Si, Fe-Cr, Fe-Mn, Fe-Mn-C, Fe-Mn-Ni, Fe-Mn-Cr, Fe-C, Fe-N, Fe-Ni-C, Fe-Cr-C, Fe-Cu-C, Fe-Si-C, Fe-Cr-Ni-C, Co, Co-Ni , Co-Fe, Mn-Cu, In-Tl, In-Tl-Li, Na, Zr, Tl, Hf, Ti, Ti-Al, Ti-Cu, Ti-Cr, Ti-Fe, Ti-Mn, Ti-Mo, Ti-V, Ti-Zr, Ti-Al-V, Zr-U, Cu-Al-Ni, Cu-Al, Ag-Cd, Au-Cd, Au-Cd-Cu, Li, Li-Mg, Cu-Zn, U, U-Cr, Hg, etc. In the present invention, the metal preferably contains Fe, Cr or Ni, more preferably contains Fe and Cr, and most preferably is stainless steel. According to such a preferred range, the bending strength can be made more excellent.

[0021] The above-mentioned "oriented in the (100) direction" means that the crystal orientation angle detected by X-ray diffraction is oriented in the (100) direction, and more specifically, the peak ratio in the (100) direction to the total peaks of the metal film detected by X-ray diffraction is 50% or more, and preferably the peak ratio is 90% or more.

[0022] In the present invention, the thickness of the metal film is preferably 100 μm or less, and more preferably 1 μm to 10 μm, which is preferable because the metal film is superior as an intermediate film for crystal growth of the functional film.

[0023] The laminated structure can be easily obtained by, for example, laminating a compound film containing Hf as a first intermediate film on a crystal substrate, then laminating a metal film containing a metal that undergoes martensitic transformation by heat treatment or processing as a second intermediate film, and then laminating a piezoelectric film (hereinafter also referred to as a "piezoelectric layer") by crystal growth directly or via another layer, and then peeling off the crystal substrate. As a crystal growth means in the crystal growth, for example, a known crystal growth means such as a PLD method or a CVD method can be mentioned. Note that the peeling means may be any known peeling means as long as it can peel off the crystal substrate from the piezoelectric film. The peeling means may be a means for removing the crystal substrate, and known removal means such as dry etching and wet etching can also be used for the peeling as long as it does not impede the object of the present invention. Note that in the present invention, it is preferable to peel off the crystal substrate by wet etching. For the wet etching means, a known etching agent such as a strong alkali can be suitably used.

[0024] The crystal substrate (hereinafter, simply referred to as "substrate") is not particularly limited as long as the object of the present invention is not hindered, such as the substrate material, and may be a known crystal substrate. It may be an organic compound or an inorganic compound. In the present invention, it is preferable that the crystal substrate contains an inorganic compound. In the present invention, it is preferable that the substrate has crystals on a part or all of the surface, more preferably a crystal substrate having crystals on all or a part of the main surface on the crystal growth side, and most preferably a crystal substrate having crystals on the entire main surface on the crystal growth side. The crystal is not particularly limited as long as the object of the present invention is not hindered, and the crystal structure is not particularly limited, but it is preferable that it is a cubic, tetragonal, trigonal, hexagonal, orthorhombic, or monoclinic crystal, and more preferably a crystal oriented in (100) or (200). In addition, the crystal substrate may have an off angle, and examples of the off angle include an off angle of 0.2° to 12.0°. Here, the "off angle" refers to the angle between the substrate surface and the crystal growth surface. The shape of the substrate is not particularly limited as long as it is plate-like and serves as a support for the epitaxial film. It may be an insulating substrate or a semiconductor substrate, but in the present invention, the substrate is preferably a Si substrate, more preferably a crystalline Si substrate, and most preferably a crystalline Si substrate oriented in (100). In addition to the Si substrate, examples of the substrate material include one or more metals belonging to Groups 3 to 15 of the periodic table or oxides of these metals. The shape of the substrate is not particularly limited, and may be an approximately circular shape (e.g., a circular shape, an elliptical shape, etc.) or a polygonal shape (e.g., a triangular shape, a square shape, a rectangular shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a nonagonal shape, etc.), and various shapes can be suitably used. In addition, in the present invention, a large-area substrate can be used, and the area of ​​the epitaxial film can be increased by using such a large-area substrate.

[0025] In the present invention, the crystal substrate preferably has a flat surface, but it is also preferable that the crystal substrate has an uneven shape on a part or all of the surface, since this can improve the quality of the crystal growth of the epitaxial film. The crystal substrate having the uneven shape may have an uneven portion consisting of a concave or convex portion formed on a part or all of the surface, and the uneven portion is not particularly limited as long as it is composed of a convex portion or a concave portion, and may be an uneven portion consisting of a convex portion, an uneven portion consisting of a concave portion, or an uneven portion consisting of a convex portion and a concave portion. The uneven portion may be formed of regular convex portions or concave portions, or may be formed of irregular convex portions or concave portions. In the present invention, it is preferable that the uneven portion is formed periodically, and it is more preferable that the uneven portion is patterned periodically and regularly. The shape of the uneven portion is not particularly limited, and examples thereof include a stripe shape, a dot shape, a mesh shape, and a random shape, but in the present invention, a dot shape or a stripe shape is preferable, and a dot shape is more preferable. In addition, when the unevenness is patterned periodically and regularly, the pattern shape of the unevenness is preferably a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon, a circle, or an ellipse. In addition, when the unevenness is formed in a dot shape, the lattice shape of the dots is preferably a lattice shape such as a square lattice, an oblique lattice, a triangular lattice, or a hexagonal lattice, and more preferably a triangular lattice shape. The cross-sectional shape of the concave or convex part of the unevenness is not particularly limited, but examples thereof include a U-shape, a U-shape, an inverted U-shape, a wave shape, or a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon. In addition, the thickness of the crystal substrate is not particularly limited, but is preferably 50 to 2000 μm, and more preferably 100 to 1000 μm.

[0026] The piezoelectric layer is not particularly limited as long as it is a piezoelectric layer made of the piezoelectric material. The piezoelectric material may be a known piezoelectric material, but in the present invention, it is preferable that the piezoelectric material contains Pb and Ti. In this specification, the terms "film" and "layer" may be interchangeable depending on the case or situation.

[0027] In the present invention, it is preferable that a first intermediate film is laminated on a crystal substrate, and then a second intermediate film is laminated, and then the piezoelectric layer is laminated directly or via another layer. Examples of the other layer include a metal film, a conductive oxide film, or a conductive nitride film. Examples of the conductive oxide film include a conductive oxide film containing Sr and / or Ru. Examples of the conductive nitride film include a conductive nitride film containing Hf. The metal film in the other layer is preferably made of a metal different from the metal, and examples of the metal include gold, silver, platinum, palladium, silver-palladium, copper, nickel, and alloys thereof. The above-mentioned lamination means can be laminated by using any known film forming means. In the present invention, the above-mentioned film forming means is preferably deposition (including MBE) or sputtering. The thickness of each layer is not particularly limited, but is preferably 10 nm to 100 μm, more preferably 50 nm to 30 μm.

[0028] The laminated structure obtained as described above is peeled off from the crystal substrate by appropriate wet etching or the like, and is suitably used as a piezoelectric body in the element such as a piezoelectric element by using a known means. For example, a new high-performance piezoelectric element can be easily produced by winding the obtained piezoelectric body around a substantially cylindrical base and providing a reflector and an interdigital electrode in order from the joint. The element is also suitably used in an electronic device according to a conventional method. For example, various electronic devices can be constructed by connecting the laminated structure as a piezoelectric element to a power source or an electric / electronic circuit, mounting it on a circuit board, or packaging it. In the present invention, the electronic device is preferably a piezoelectric device, and can be used as a piezoelectric device in electronic devices such as inkjet printer heads, microactuators, gyroscopes, and motion sensors. For example, if an amplifier and a rectifier circuit are connected and packaged, it can be used in various sensors such as magnetic sensors. It can also be applied to constant-voltage driven memories, and for example, if a storage element and a rectifier power management circuit are connected, it becomes an energy conversion device (energy harvester) that generates power from an external magnetic field or vibration. The energy conversion device is incorporated into a power supply system or a wearable terminal (such as an earphone / hearable device, a smart watch, a smart glass (eyeglasses), a smart contact lens, an artificial ear, or a cardiac pacemaker), etc. In the present invention, the laminated structure is preferably used in, for example, smart glasses, an AR headset, a MEMS mirror for a LiDAR system, a piezoelectric MEMS ultrasonic transducer (PMUT) for advanced medical treatment, a piezo head for a commercial and industrial 3D printer, etc.

[0029] The electronic device is suitably used in electronic devices in the usual manner, and can be applied to various electronic devices other than the above-mentioned electronic devices, and more specifically, suitable examples include liquid ejection heads, liquid ejection devices, vibration wave motors, optical devices, vibration devices, imaging devices, piezoelectric acoustic parts, audio playback devices having the piezoelectric acoustic parts, audio recording devices, mobile phones, various information terminals, and the like.

[0030] Furthermore, the electronic device is also applied to a system in the usual manner, and an example of such a system is a sensor system.

[0031] Preferred embodiments of the present invention will now be described with reference to the drawings, but the present invention is not limited to these preferred embodiments.

[0032] FIG. 1 shows an example of a suitable element of the present invention. In the element of FIG. 1, a piezoelectric body 12 is wound around the side surface of a cylindrical substrate, and an interdigital transducer 10 and a reflector 20 are formed on the piezoelectric body 12 on the side surface. The interdigital transducer 10 and the reflector 20 may be formed by using known means. When a voltage is applied to the interdigital transducer 10, the piezoelectric effect of the piezoelectric body 12 causes distortion on the piezoelectric body between adjacent electrode fingers of the interdigital transducer 10, exciting a surface wave. The interdigital transducer has electrode fingers arranged periodically, and the surface wave is excited most strongly when the wavelength is equal to the electrode finger period. Since the frequency is determined by the electrode spacing formed on the surface, high frequencies can be easily accommodated by photolithography or the like.

[0033] The element is suitably used in electronic devices according to the usual method. For example, the element can be connected as a piezoelectric element to a power source or an electric / electronic circuit, and mounted on a circuit board or packaged to form various electronic devices. In the present invention, the electronic device is preferably a piezoelectric device, and can be used as a piezoelectric device in electronic devices such as gyroscopes and motion sensors. In addition, for example, if an amplifier and a rectifier circuit are connected and packaged, the electronic device can be used as various sensors such as magnetic sensors.

[0034] The electronic device is suitably used in electronic devices in the usual manner, and can be applied to various electronic devices other than the above-mentioned electronic devices, and more specifically, suitable examples include liquid ejection heads, liquid ejection devices, vibration wave motors, optical devices, vibration devices, imaging devices, piezoelectric acoustic parts, audio playback devices having the piezoelectric acoustic parts, audio recording devices, mobile phones, various information terminals, and the like.

[0035] Furthermore, the electronic device is also applied to a system in the usual manner, and an example of such a system is a sensor system. EXAMPLES

[0036] Example 1 The crystal growth surface of the Si substrate (100) was treated by RIE, and the metal of the deposition source was thermally reacted with nitrogen by deposition in the presence of nitrogen to form a HfZrN single crystal on the Si substrate. The deposition conditions for this film formation were as follows: Vapor deposition source: Hf, Zr Voltage: 3.5~4.75V Pressure: 3x10 -2 ~6×10 -2 Pa Substrate temperature: 450~700℃

[0037] The deposition apparatus used in the deposition of the HfZrN single crystal is shown in Fig. 8. The deposition apparatus in Fig. 8 includes at least metal sources 1101a-1101b in a crucible, earths 1102a-1102h, ICP electrodes 1103a-1103b, cut filters 1104a-1104b, DC power sources 1105a-1105b, RF power sources 1106a-1106b, lamps 1107a-1107b, Ar source 1108, reactive gas source 1109, power source 1110, substrate holder 1111, substrate 1112, cut filter 1113, ICP ring 1114, vacuum chamber 1115, and rotating shaft 1116. The ICP electrodes 1103a-1103b in Fig. 8 have a substantially concave curved shape or a parabolic shape curved toward the center of the substrate 1112.

[0038] As shown in FIG. 8, the substrate 1112 is fixed on the substrate holder 1111. Next, the rotating shaft 1116 is rotated using the power supply 1110 and a rotating mechanism (not shown) to rotate the substrate 1112. The substrate 112 is heated by the lamps 1107a-1107b, and the inside of the vacuum chamber 1115 is evacuated to a vacuum or reduced pressure by a vacuum pump (not shown). Then, Ar gas is introduced from the Ar source 1108 into the vacuum chamber 1115, and argon plasma is formed on the substrate 1112 using the DC power supplies 1105a-1105b, the RF power supplies 1106a-1106b, the ICP electrodes 1103a-1103b, the cut filters 1104a-1104b, and the earths 1102a-1102h, thereby cleaning the surface of the substrate 1112.

[0039] Ar gas is introduced into the vacuum chamber 1115, and a reactive gas is introduced using the reactive gas source 1109. At this time, the lamps 7a and 7b are configured to irradiate the substrate 12 with different wavelengths. The lamps 7a and 7b may be lamp heaters. The wavelength is not particularly limited as long as it does not impede the object of the present invention, and may be ultraviolet or infrared. The wavelength may be appropriately set depending on the raw material, the type of reaction, etc., and the film quality and the film formation rate can be easily improved. Also, a better quality crystal growth film can be formed by alternately turning on and off the lamps 7a to 7b.

[0040] Next, a SUS304 single crystal film was formed in the same manner as above, except that Fe, Cr and Ni were used as the metals of the deposition source.

[0041] Next, a platinum (Pt) metal film was formed as a conductive film on the single crystal film of the crystalline metal oxide by sputtering under the following conditions. Equipment: ULVAC sputtering equipment QAM-4 Pressure: 1.20 x 10 -1 Pa Target: Pt Power: 100W(DC) Thickness: 100nm Substrate temperature: 450~600℃

[0042] Next, an SRO film was formed on the conductive film by sputtering under the following conditions. Equipment: ULVAC sputtering equipment QAM-4 Power: 150W (RF) Gas: Ar Pressure: 1.8Pa Substrate temperature: 600℃ Thickness: 20nm

[0043] Next, a PbTiO3 film was formed as a piezoelectric film on the SRO film. The resulting laminated structure had good adhesion and crystallinity. In addition, the crystallinity of the crystalline substrate of the laminated structure, the single crystal film of the crystalline metal oxide, and the conductive film were measured using an X-ray diffraction device. Figure 2 shows the results of the XRD measurement. As is clear from Figure 2, a SUS304 single crystal film with good crystallinity was formed, and the crystallinity of the PbTiO3 film and other films was also good.

[0044] After forming the PbTiO3 film, the Si substrate was removed by wet etching using sodium hydroxide, and the Si substrate was peeled off from the PbTiO3 film. The obtained laminated structure had flexibility.

[0045] (Exam example) As a test example, a cantilever beam of a microelement as shown in Figures 3 and 4 was fabricated using FIB FB2100 (Hitachi High-Technologies), and its fracture strength characteristics were evaluated using a nanoindenter NanoTest Xtreme (Micro Materials), as shown in Figure 5. Figure 5 shows that the fracture strength of Si was approximately 1 GPa, which was a nearly constant value. Considering that the bending strength of Si single crystal bulk material is approximately 300 MPa (paper), it was found that micromaterials have great strength. Furthermore, in the case of SUS304 single crystal thin film, the fracture strength was approximately 5 GPa, which is approximately 5 times the bending strength of Si single crystal. This means that by using SUS304 single crystal thin film for the beam of a MEMS device (movable part, equivalent to the active layer of an SOI substrate), it is expected that the displacement amount of the MEMS device will be significantly improved, as well as the life characteristics will be significantly improved.

[0046] Examples of application of the obtained piezoelectric material to elements will be described in more detail below with reference to the drawings, but the present invention is not limited to these examples. In the present invention, unless otherwise specified, elements, electronic devices, etc. can be manufactured from the piezoelectric material by known means.

[0047] FIG. 3 shows an example of an element according to a preferred embodiment of the present invention. The element in FIG. 3 differs from FIG. 1 in that it includes a SAW receiver for detecting SAW. In the element in FIG. 3, a piezoelectric body 12 is wound around the side surface of a cylindrical substrate, and two interdigital transducers 13 and two reflectors 20 are formed on the piezoelectric body 12 on the side surface of the substrate by using known means. When a voltage is applied to the interdigital transducer 13, the piezoelectric effect of the piezoelectric body 12 causes distortion on the piezoelectric body between adjacent electrode fingers of the interdigital transducer 13, and a surface wave is excited. In addition, a SAW receiver 19 is connected to the interdigital transducer 13, and is configured to detect a surface acoustic wave propagating in the SAW propagation path 14 shown in FIG. 1. The surface acoustic wave propagates on the surface of the piezoelectric body 12 in the directions D1 and D2 shown in FIG. 4 by the reflector 20, that is, the surface acoustic wave propagates in the directions opposite to each other. This makes it possible to fabricate an environmentally friendly sensor with high accuracy and sensitivity. [Industrial Applicability]

[0048] The element of the present invention can be used in a variety of applications, but is particularly suitable for use as a piezoelectric sensor, and is applied to, for example, electronic devices for sensor systems. [Explanation of symbols]

[0049] 1 Crystal substrate (Si substrate) 2 HfZrN film 3 SUS membrane (FeCrNi membrane) 4 Pt membrane 5 SRO membrane 6 Piezoelectric layer (PbTiO film) 10 Blank-shaped electrode 11 Reflective Bus Bar 12 Piezoelectric 13 Reflector electrode finger 14 Propagation route 15 Extraction electrode 19 SAW Receiver 20 reflector 1101a~101b Metal source 1102a~102j Earth 1103a~103b ICP electrode 1104a~104b Cut filter 1105a~105b DC power supply 1106a~106b RF power supply 1107a~107b Lamp 1108 Ar source 1109 Reactive gas source 1110 Power supply 1111 Board holder 1112 Board 1113 Cut filter 1114 ICP Ring 1115 Vacuum chamber 1116 Rotating shaft

Claims

1. An element comprising one or more interdigital transducers provided on a piezoelectric body, the piezoelectric body being in the form of a sheet.

2. 2. The element according to claim 1, wherein the piezoelectric body is bonded to a substrate.

3. 3. The element according to claim 2, wherein the substrate is cylindrical, approximately cylindrical, barrel-shaped, or approximately barrel-shaped, the piezoelectric body is wound around the substrate to form a circle or approximately circle, and the interdigital electrode is disposed so that surface acoustic waves can propagate in a circumferential direction or approximately circumferential direction of the circle or approximately circle.

4. 4. The element according to claim 3, wherein a reflector is provided in the propagation path of the surface acoustic wave.

5. 5. The element according to claim 4, wherein two or more reflectors are provided, and the joints between the piezoelectric bodies formed by the winding are provided between the reflectors.

6. 6. The element according to claim 3, wherein the interdigital transducer comprises a SAW generating means for generating the surface acoustic waves and a SAW receiving means for receiving the surface acoustic waves.

7. 6. The element according to claim 1, wherein the piezoelectric body is formed on a metal film.

8. 8. The element according to claim 7, wherein the piezoelectric body and the metal film are oriented in the (100) direction.

9. 8. The element according to claim 7, wherein the metal film comprises two or more metal layers.

10. 8. The element according to claim 7, wherein the metal film contains a metal that undergoes martensitic transformation upon heat treatment or processing, and the piezoelectric body and the metal film are oriented in substantially the same crystal axis direction.

11. The device according to claim 10 , wherein the metal film comprises Fe.

12. The device of claim 10 , wherein the metal film comprises Cr.

13. The element according to any one of claims 1 to 5, wherein the piezoelectric body is made of a single crystal film.

14. An electronic device, an electronic equipment or a system including an element, wherein the element is the element according to any one of claims 1 to 5.

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