Elements, electronic devices, electronic equipment and systems

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, a type of piezoelectric element, has an interdigital transducer (IDT) on a piezoelectric substrate such as a quartz substrate. The interdigital transducer is a pair of interdigital transducers, with comb-shaped electrodes formed on the piezoelectric substrate so that they face each other without contact. By applying an AC voltage to the interdigital transducers, the piezoelectric effect and inverse piezoelectric effect of the piezoelectric substrate can vibrate the surface and near the surface of the piezoelectric substrate on which the interdigital transducers are formed in a frequency band. Depending on the combination and configuration of 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] Furthermore, in recent years, as mobile terminal devices used in mobile communications have become smaller and lighter, there has been a demand for surface acoustic wave elements with even higher accuracy to achieve high communication quality. To meet this demand, spherical SAW sensors (ball SAW sensors) and other devices have been considered (Patent Document 1). Ball SAW sensors utilize the phenomenon of SAW's natural collimated beam traveling multiple times around the globe, significantly increasing the interaction distance compared to planar sensors, making them useful for achieving high sensitivity. However, there are cost issues, such as a complicated manufacturing process, and SAW devices have many issues with high-frequency characteristics, making them far from satisfactory. Furthermore, with the growing demand for energy conservation to address environmental issues, a new SAW element that can solve these issues has been eagerly awaited. [Prior art documents] [Patent documents]

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

[0005] The present invention aims to provide elements, electronic devices, electronic equipment and systems that are environmentally friendly and have excellent precision. [Means for solving the problem]

[0006] As a result of extensive research into achieving the above-mentioned object, the inventors have succeeded in creating a laminated structure in which a piezoelectric material is laminated on a metal film with the piezoelectric material 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 transducers are provided on a piezoelectric material, and the piezoelectric material is in sheet form. They have also found that such an element can solve all of the above-mentioned conventional problems at once. Furthermore, 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 in which one or more interdigital transducers are provided on a piezoelectric body, the piezoelectric body being in the form of a sheet. [2] The element according to [1] above, 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 electrode is 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 the propagation path of the surface acoustic wave. [5] The element according to [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] The element according to any one of [3] to [5], 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] 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 the (100) direction. [9] The element according to [7] or [8], wherein the metal film is composed of two or more 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 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, wherein the element is the element according to any one of [1] to

[13] above. [Effects 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 explanation of the drawings]

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

[0010] The element of the present invention is not particularly limited as long as it comprises one or more interdigital transducers disposed on a sheet-like piezoelectric body. In the present invention, the piezoelectric body is preferably bonded to a substrate. The bonding may be achieved by a known bonding method, preferably a metal bonding method or a bonding method. The metal bonding method may be a known metal bonding method, or a metal film may be bonded to the piezoelectric body. However, in the present invention, it is preferable to form the piezoelectric body on the metal film and use the resulting laminated structure. In the present invention, the piezoelectric body is preferably formed on a metal film, and more preferably, the piezoelectric body and the metal film are each oriented in the (100) direction. In the present invention, the metal film preferably comprises two or more metal layers, one of which preferably contains a metal that undergoes martensitic transformation upon heat treatment or processing, and more preferably, the piezoelectric body and the metal film are each oriented in approximately the same crystal axis direction. This preferred range can improve the precision of the element. The metal film preferably contains Fe, and more preferably contains Cr. Within this preferred range, the piezoelectric element has better flexibility, and can more easily achieve excellent precision in an element that involves bending the piezoelectric element. The piezoelectric element is preferably made of a single crystal film. The bonding means is not particularly limited, but a suitable example is one that uses a known adhesive.

[0011] In addition, in the present invention, it is preferable that the base be cylindrical, approximately cylindrical, barrel-shaped, or approximately barrel-shaped, the piezoelectric element be wound around the base to form a circle or approximately circle, and the interdigital transducer be disposed so that surface acoustic waves can propagate in the circumferential direction or approximately circumferential direction of the circle or approximately circle. This preferred range can further improve the accuracy of the element as a SAW device, without, for example, using a ball SAW. In addition, in the present invention, it is preferable that a reflector be disposed in the propagation path of the surface acoustic waves, and more preferably, two or more reflectors are disposed, and the joints between the piezoelectric elements formed by the winding are disposed between the reflectors. This preferred range can significantly simplify the manufacturing process of the element and further improve versatility. In addition, in the present invention, it is preferable that the interdigital transducer include a SAW generating means for generating the surface acoustic waves and a SAW receiving means for receiving the surface acoustic waves. This preferred range can easily improve the accuracy of the element, 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. However, in the present invention, it is more preferable that a reflector is provided on the piezoelectric body that is 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 preferably located adjacent to an interdigital transducer (hereinafter also referred to as "IDT electrode") in the propagation direction of the SAW, as shown in Fig. 1. The reflector may be, for example, an electrode formed in a lattice pattern, and in the present invention, it is preferable that the reflector has a pair of 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 shapes 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 busbars 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 constant width and has the same length. These reflective electrode fingers 13 are, for example, arranged side by side in the propagation direction of the SAW. The number of the reflective electrode fingers 13 is usually set so that the reflectivity of the SAW in the intended mode is approximately 100% or more. A theoretically necessary minimum number is, for example, several to 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 also preferable that the element has the interdigital transducer equipped with a SAW generating means for generating the surface acoustic waves and a SAW receiving means for receiving the surface acoustic waves. Furthermore, in the present invention, it is more preferable that a total of two or more interdigital transducers are provided, sandwiching the joint between the two reflectors and the piezoelectric body, as shown in Fig. 3. This configuration further improves the accuracy of correction using the signal, making it easier to realize a sensor with higher sensitivity.

[0017] Here, a preferred example of correction using the SAW receiving means 19 of 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 element 12 by the electrode fingers of the interdigital transducer, and a SAW of a predetermined mode is excited, propagating along the piezoelectric element 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, forming a standing wave with the electrode finger pitch as half the wavelength. The standing wave is converted into an electrical signal of the same frequency as the standing wave and extracted by the electrode fingers of the interdigital transducer. Here, a phase difference occurs between the wave propagating in the D1 direction and the wave propagating in the D2 direction of the SAW to which the rotational angular velocity is applied. Therefore, correction can be performed using, for example, the following equation (1) that represents the phase difference:

number

[0018] The element can be easily fabricated using the laminated structure. In the present invention, if the laminated structure includes a crystal substrate, it is preferable to peel off the crystal substrate before use. The laminated structure is preferably a flexible laminated structure having at least a second layer stacked on a first layer, the first layer being made of a metal film, and the second layer being 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 properties at high frequencies, etc.

[0019] In the present invention, it is preferable that the piezoelectric film and the metal film are each oriented in the (100) direction. Furthermore, in the present invention, it is preferable that the piezoelectric film is a single-crystal film, since this has better piezoelectric properties and durability. It is preferable that the piezoelectric film is a PTO film or a PZT film. Furthermore, in the present invention, it is preferable that the metal contains Fe, and more preferably further contains Cr. This preferable range allows for better crystal growth and a higher-quality crystal film to be obtained. It is also preferable that a conductive oxide film is disposed between the metal film and the piezoelectric film, and that the metal film is disposed on a conductive nitride film. When the conductive oxide film is disposed, it is preferable that the conductive oxide film contains Sr and / or Ru, and when the conductive nitride film is disposed, 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 metal whose atomic ratio 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, more preferably 0.8 or more. The metal is preferably a metal that undergoes martensitic transformation upon heat treatment or processing, but is not particularly limited and may be any 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, and 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. Within these preferred ranges, superior bending strength can be achieved.

[0021] The "orientation in the (100) direction" mentioned above means that the crystal orientation angle detected by X-ray diffraction is oriented in the (100) direction. 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 makes it superior as an intermediate film for crystal growth in a functional film.

[0023] The laminated structure can be easily obtained, for example, by laminating a compound film containing Hf as a first intermediate film on a crystal substrate, followed by laminating a metal film containing a metal that undergoes martensitic transformation upon 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, either directly or via another layer, and then peeling off the crystal substrate. Examples of crystal growth methods include known crystal growth methods such as PLD and CVD. The peeling method may be any known peeling method that can peel the crystal substrate from the piezoelectric film. The peeling method may also be a means for removing the crystal substrate, and known removal methods such as dry etching and wet etching can also be used for the peeling, as long as they do not impede the objectives of the present invention. In the present invention, the crystal substrate is preferably peeled off by wet etching. Known etching agents, such as strong alkalis, can be suitably used as the wet etching method.

[0024] The crystal substrate (hereinafter simply referred to as "substrate") is not particularly limited in terms of substrate material, etc., as long as it does not impede the objectives of the present invention, and may be a known crystal substrate. It may be an organic compound or an inorganic compound. In the present invention, the crystal substrate preferably contains an inorganic compound. In the present invention, the substrate preferably has crystals on a portion or all of its surface, more preferably a crystal substrate having crystals on all or a portion of its 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 it does not impede the objectives of the present invention, and the crystal structure is also not particularly limited. However, crystals of a cubic, tetragonal, trigonal, hexagonal, orthorhombic, or monoclinic system are preferred, and crystals oriented in a (100) or (200) plane are more preferred. The crystal substrate may also 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-shaped and serves as a support for the epitaxial film. It may be an insulating substrate or a semiconductor substrate. However, in the present invention, the substrate is preferably a Si substrate, more preferably a crystalline Si substrate, and most preferably a (100)-oriented crystalline Si substrate. Examples of the substrate material include Si substrates and 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 substantially circular (e.g., circular, elliptical, etc.) or polygonal (e.g., triangular, square, rectangular, pentagonal, hexagonal, heptagonal, octagonal, nonagonal, etc.), and various shapes can be suitably used. Furthermore, in the present invention, a large-area substrate can be used, and the use of such a large-area substrate allows for a larger area of ​​the epitaxial film.

[0025] In the present invention, the crystal substrate preferably has a flat surface. However, it is also preferable for the crystal substrate to have an uneven surface on part or all of its surface, as this can improve the quality of the crystal growth of the epitaxial film. The crystal substrate having an uneven surface may have an uneven surface consisting of concave or convex portions formed on part or all of its surface. The uneven surface is not particularly limited as long as it consists of convex or concave portions. It may be an uneven surface consisting of convex portions, an uneven surface consisting of concave portions, or an uneven surface consisting of convex and concave portions. The uneven surface may be formed of regular convex or concave portions, or irregular convex or concave portions. In the present invention, the uneven surface is preferably formed periodically, and more preferably in a periodic and regularly patterned form. The shape of the uneven surface is not particularly limited, and examples thereof include stripes, dots, meshes, and random patterns. In the present invention, a dot or stripe pattern is preferred, and a dot pattern is more preferred. Furthermore, when the concave-convex portions are patterned periodically and regularly, the pattern shape of the concave-convex portions is preferably a polygonal shape such as a triangle, a quadrangle (e.g., a square, a rectangle, or a trapezoid), a pentagon, or a hexagon, or a circle, an ellipse, or the like. When the concave-convex portions are formed in a dotted pattern, 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. The cross-sectional shape of the concave or convex portions of the concave-convex portions is not particularly limited, but examples thereof include a U-shape, an inverted U-shape, a wave shape, or a polygonal shape such as a triangle, a quadrangle (e.g., a square, a rectangle, or a trapezoid), a pentagon, or a hexagon. 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 used interchangeably depending on the case or situation.

[0027] In the present invention, it is preferable to laminate a first intermediate film on a crystal substrate, then laminate a second intermediate film, and then laminate the piezoelectric layer 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 mentioned above, such as gold, silver, platinum, palladium, silver-palladium, copper, nickel, or an alloy thereof. The above-mentioned lamination means can be any known film-forming means. In the present invention, the film-forming means is preferably vapor 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 from the crystal substrate by appropriate wet etching or the like, and is suitably used as a piezoelectric body in elements such as piezoelectric devices using known means. For example, a high-performance novel piezoelectric element can be easily fabricated by winding the obtained piezoelectric body around a substantially cylindrical substrate and providing a reflector and an interdigital transducer in this order from the joining point. Furthermore, the element is suitably used in electronic devices according to conventional methods. 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. Furthermore, for example, by connecting an amplifier and a rectifier circuit and packaging it, it can be used as various sensors such as magnetic sensors. It can also be used in constant-voltage driven memories, and for example, by connecting a storage element and a rectifier power management circuit, it can be used as an energy conversion device (energy harvester) that generates power from external magnetic fields or vibrations. The energy conversion device is incorporated into power supply systems and wearable terminals (earphones / hearable devices, smart watches, smart glasses (eyeglasses), smart contact lenses, cochlear implants, cardiac pacemakers, etc.) In the present invention, the laminated structure is preferably used in, for example, smart glasses, AR headsets, MEMS mirrors for LiDAR systems, piezoelectric MEMS ultrasonic transducers (PMUTs) for advanced medical applications, and piezo heads for commercial and industrial 3D printers.

[0029] The electronic device is suitably used in electronic devices in the usual manner, and can be applied to various electronic devices in addition to the above-mentioned electronic devices, and more specific examples of suitable electronic devices include liquid ejection heads, liquid ejection apparatuses, vibration wave motors, optical devices, vibration devices, imaging devices, piezoelectric acoustic components, and audio playback devices, audio recording devices, mobile phones, and various information terminals that have such piezoelectric acoustic components.

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

[0031] Preferred embodiments of the present invention will be described below 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 element 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 element 12 on the side surface. The interdigital transducer 10 and the reflector 20 may be formed using known methods. When a voltage is applied to the interdigital transducer 10, the piezoelectric effect of the piezoelectric element 12 causes strain on the piezoelectric element between adjacent electrode fingers of the interdigital transducer 10, exciting a surface wave. The interdigital transducer has periodic arrangement of electrode fingers, and the surface wave is excited most strongly when the wavelength is equal to the electrode finger period. Because the frequency is determined by the electrode spacing formed on the surface, high frequencies can be easily accommodated by photolithography or other processes.

[0033] The element is suitably used in electronic devices according to conventional methods. For example, various electronic devices can be constructed by connecting the element as a piezoelectric element to a power source or an electric / electronic circuit, and 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 gyroscopes and motion sensors. Furthermore, 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 in addition to the above-mentioned electronic devices, and more specific examples of suitable electronic devices include liquid ejection heads, liquid ejection apparatuses, vibration wave motors, optical devices, vibration devices, imaging devices, piezoelectric acoustic components, and audio playback devices, audio recording devices, mobile phones, and various information terminals that have such piezoelectric acoustic components.

[0035] Furthermore, the electronic device is also applied to a system in the usual manner, and examples of such a system include a sensor system. [Example]

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

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

[0038] As shown in FIG. 8, a substrate 1112 is secured on a substrate holder 1111. Next, a power supply 1110 and a rotation mechanism (not shown) are used to rotate a rotation shaft 1116, thereby rotating the substrate 1112. The substrate 1112 is heated by lamps 1107a-1107b, and a vacuum chamber 1115 is evacuated using a vacuum pump (not shown) to create a vacuum or reduced pressure. Thereafter, Ar gas is introduced from an Ar source 1108 into the vacuum chamber 1115, and argon plasma is formed on the substrate 1112 using DC power supplies 1105a-1105b, RF power supplies 1106a-1106b, ICP electrodes 1103a-1103b, cut filters 1104a-1104b, and 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 each be a lamp heater. 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 can easily improve the film quality and film formation rate. A better quality crystal growth film can also be formed by alternately turning the lamps 7a to 7b on and off.

[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 evaporation 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: 1.20×10 -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 on the SRO film as a piezoelectric film. The resulting laminated structure had good adhesion and crystallinity. Furthermore, the crystal substrate of the laminated structure, the single crystal film of the crystalline metal oxide, and the conductive film were measured for their respective crystallinity using an X-ray diffractometer. 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 materials was also good.

[0044] After the PbTiO3 film was formed, the Si substrate was removed by wet etching using sodium hydroxide, and the Si substrate was peeled off from the PbTiO3 film. The resulting laminated structure was flexible.

[0045] (Test example) As a test example, a cantilever beam of a microelement, as shown in Figures 3 and 4, was fabricated using a FIB FB2100 (Hitachi High-Technologies Corporation). Its fracture strength characteristics were evaluated using a nanoindenter, NanoTest Xtreme (Micro Materials), and the results are shown in Figure 5. Figure 5 shows that the fracture strength of Si was approximately 1 GPa, a fairly constant value. Considering that the bending strength of bulk Si single crystal material is approximately 300 MPa (according to a paper), this demonstrates the significant strength of micromaterials. Furthermore, the fracture strength of a SUS304 single crystal thin film was approximately 5 GPa, approximately five times the bending strength of a Si single crystal. This suggests that using a SUS304 single crystal thin film for the beams of MEMS devices (the moving part, equivalent to the active layer of an SOI substrate) can be expected to significantly improve not only the displacement of MEMS devices but also their lifespan characteristics.

[0046] Examples of applications 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 application examples. In the present invention, elements, electronic devices, etc. can be manufactured from the piezoelectric material using known means unless otherwise specified.

[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 that in FIG. 1 in that it includes a SAW receiver for detecting SAWs. In the element in FIG. 3, a piezoelectric element 12 is wound around the side surface of a cylindrical substrate. Two interdigital transducers 13 and two reflectors 20 are formed on the piezoelectric element 12 on the side surface of the substrate using known techniques. When a voltage is applied to the interdigital transducers 13, the piezoelectric effect of the piezoelectric element 12 generates strain on the piezoelectric element between adjacent electrode fingers of the interdigital transducer 13, exciting a surface wave. A SAW receiver 19 is connected to the interdigital transducer 13, enabling detection of surface acoustic waves propagating through the SAW propagation path 14 shown in FIG. 1. The reflectors 20 cause the surface acoustic waves to propagate along the surface of the piezoelectric element 12 in directions D1 and D2 shown in FIG. 4, i.e., in opposing directions. This allows the fabrication of 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 Interdigital electrode 11 Reflective busbar 12 Piezoelectric 13 Reflector electrode finger 14 Propagation Path 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 Lamps 1108 Ar source 1109 Reactive Gas Source 1110 Power supply 1111 PCB holder 1112 board 1113 Cut Filter 1114 ICP Ring 1115 Vacuum chamber 1116 Rotation axis

Claims

1. A cylindrical, approximately cylindrical, barrel-shaped, or approximately barrel-shaped base body; a piezoelectric body wound around the base to form a circular or substantially circular shape; Including, An element in which one or more interdigital transducers are provided on the piezoelectric body so that surface acoustic waves can propagate in a circumferential direction or a substantially circumferential direction of the circular or substantially circular shape, the piezoelectric body is bonded to the base; Two or more reflectors are provided in a propagation path of the surface acoustic wave, An element characterized in that the joints between the piezoelectric bodies formed by the winding are provided between the reflectors.

2. A cylindrical, approximately cylindrical, barrel-shaped or approximately barrel-shaped base body; an annular piezoelectric body wound around and bonded to a side peripheral surface of the base body; Including, an element in which one or more interdigital transducers are provided on the outer peripheral surface of the annular piezoelectric body so that surface acoustic waves can propagate in the circumferential direction of the annular piezoelectric body, two reflectors are provided on the outer peripheral surface of the annular piezoelectric body and within a propagation path of the surface acoustic wave; the annular piezoelectric element includes a joint portion where one end and the other end of the strip-shaped piezoelectric element are joined together, The element is characterized in that the joint is provided between the two reflectors.

3. An element as described in claim 2, wherein the two reflectors are adjacent to each other across the joint.

4. An element as described in claim 2, wherein the one or more interdigital electrodes are provided on the outer surface of the annular piezoelectric body, opposite the joint side of one of the two reflectors, and opposite the joint side of the other of the two reflectors.

5. 5. The element according to claim 1, 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.

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

7. 7. The element according to claim 6, wherein the piezoelectric body and the metal film are oriented in the (100) direction.

8. 7. The element according to claim 6, wherein the metal film comprises two or more metal layers.

9. 7. The element according to claim 6, 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.

10. The device of claim 9 , wherein the metal film comprises Fe.

11. The device of claim 9 , wherein the metal film comprises Cr.

12. The element according to any one of claims 1 to 4, wherein the piezoelectric body is made of a single crystal film.

13. 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 4.

Images