Vibration element

Abstract

The invention provides a resonator element capable of suppressing reduction of vibration intensity and realizing a high Q value. A resonator element (100) that uses a piezoelectric body comprising a sphalerite-type single crystal is provided with a ring-shaped resonator unit (1) in which a plurality of first resonator units (161, 162) and a plurality of second resonator units (163, 164) are alternately arranged on at least a portion thereof, the resonator unit (1) having: first electrodes (111, 112) provided on the plurality of first resonator units (161, 162), respectively, and second electrodes (112, 112) provided on the plurality of second resonator units (163, 164), respectively; second electrodes (113, 114) respectively provided on the plurality of second vibrating parts (163, 164); a first connection part (11b) that electrically connects the first electrodes to each other; and a second connection section (11c) that electrically connects the second electrodes to each other, the plurality of first electrodes (111, 112) and the plurality of second electrodes (113, 114) being alternately arranged on a plane perpendicular to the [001] axis of the single crystal.

Description

Technical Field

[0001] The present invention relates to a vibration element. Background Art

[0002] Conventionally, various vibration elements that vibrate a vibration part by using a plurality of unit oscillators have been known. For example, Patent Document 1 discloses a Lame mode vibrating crystal oscillator in which a plurality of small vibration parts are two-dimensionally arranged.

[0003] In the Lame mode vibrating crystal oscillator of Patent Document 1, vibration is performed with equal intensity in two directions, that is, the row direction which is one arrangement direction in the two-dimensional arrangement and the column direction which is orthogonal to the row direction. Here, the resonance frequencies corresponding to these two directions depend on the width dimension of the vibration part. Therefore, in order to vibrate in harmony in these two directions, it is necessary to make the dimensions of the row direction and the column direction of the vibration part the same. However, if the resonance frequency is increased, the wavelength that contributes to resonance becomes shorter. Therefore, in the case of a high resonance frequency, the vibration intensity may decrease due to errors such as processing accuracy. If the vibration intensity decreases, the value of the quality factor Q, that is, the Q value, will decrease.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-111434 Summary of the Invention

[0005] The vibration element of the present invention for solving the above problems uses a piezoelectric body composed of a zinc blende type single crystal, and is characterized in that it includes a vibration part, the vibration part is annular, and a plurality of first vibration parts and a plurality of second vibration parts are alternately arranged on at least a part thereof. The vibration part has: first electrodes respectively provided on the plurality of first vibration parts; second electrodes respectively provided on the plurality of second vibration parts; a first connection part that electrically connects the first electrodes to each other; a second connection part that electrically connects the second electrodes to each other, and the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[001] axis of the single crystal. Brief Description of the Drawings

[0006] Figure 1 A perspective view of the vibration element according to Embodiment 1 of the present invention as viewed from the (001) plane side of the cubic crystal.

[0007] Figure 2 A schematic diagram showing a situation where a longitudinal wave is reflected as a transverse wave by a first reflection part, a transverse wave is reflected as a transverse wave by a second reflection part, and a transverse wave is reflected as a longitudinal wave by a third reflection part.

[0008] Figure 3 A graph showing the relationship between the incident angle and the reflection angle, the incident angle and the reflection amplitude, and the incident angle and the phase change when a longitudinal wave is incident.

[0009] Figure 4 A graph showing the relationships between the incident angle and the reflection angle, the incident angle and the reflection amplitude, and the incident angle and the phase change when a shear wave is incident.

[0010] Figure 5 A perspective view of the periphery of the position where the first connection portion and the second connection portion of the vibration element of Example 1 of the present invention overlap.

[0011] Figure 6 A graph showing the time variation of the voltages of the first electrode, the second electrode, and the common electrode of the vibration element of Example 1 of the present invention.

[0012] Figure 7 A schematic plan view of a part of the vibrating portion of the vibration element of Example 1 of the present invention, and a view showing the state when a voltage is applied.

[0013] Figure 8 A view showing the crystal structure of the single crystal of the piezoelectric body of the vibration element of Example 1 of the present invention.

[0014] Figure 9 A schematic view of the vibration element of Example 1 of the present invention as observed from the (001) plane side of the cubic crystal, and a view for explaining the deformation state of the unit oscillator.

[0015] Fig.10 A schematic plan view of the vibrating portion of the vibration element of Example 2 of the present invention, and a view showing the state when a voltage is applied.

[0016] Figure 11 A perspective view of the vibration element of an embodiment of the present invention as observed from the (001) plane side of the cubic crystal.

[0017] Fig.12 A schematic view showing a situation where a shear wave is reflected as a shear wave by the first reflection portion and further the shear wave is reflected as a shear wave by the second reflection portion.

[0018] Figure 13 A graph showing the relationships between the incident angle and the reflection angle, the incident angle and the reflection amplitude, and the incident angle and the phase change when a shear wave is incident.

[0019] Fig.14 A plan view of the periphery of the first vibrating portion and the second vibrating portion of the vibration element of an embodiment of the present invention.

[0020] Fig.15 A perspective view of the periphery of the position where the first connection portion and the second connection portion of the vibration element of an embodiment of the present invention overlap.

[0021] Fig.16A perspective view of the periphery of the position where the first connecting portion and the second connecting portion of the vibrating element according to an embodiment of the present invention overlap.

[0022] Figure 17 A graph showing the time variation of the voltages of the first electrode, the second electrode, and the common electrode of the vibrating element according to an embodiment of the present invention.

[0023] Figure 18 A schematic plan view of a part of the vibrating portion of the vibrating element according to an embodiment of the present invention, and a view showing the state when no voltage is applied.

[0024] Fig.19 A schematic plan view of a part of the vibrating portion of the vibrating element according to an embodiment of the present invention, and a view showing the state when a voltage is applied.

[0025] Fig. 20 A schematic plan view of a part of the vibrating portion of the vibrating element according to an embodiment of the present invention, and a view showing the state when a voltage is applied to reverse the phase at Fig.19 the time. Detailed Description

[0026] First, a general description of the present invention will be given.

[0027] The vibrating element according to the first aspect of the present invention for solving the above problems is a vibrating element using a piezoelectric body composed of a sphalerite-type single crystal. The vibrating element is characterized by including a vibrating portion, which is annular and has a plurality of first vibrating portions and a plurality of second vibrating portions alternately arranged on at least a part thereof. The vibrating portion has: first electrodes respectively provided on the plurality of first vibrating portions; second electrodes respectively provided on the plurality of second vibrating portions; a first connecting portion for electrically connecting the first electrodes to each other; and a second connecting portion for electrically connecting the second electrodes to each other. The plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[001] axis of the single crystal.

[0028] According to this aspect, on the annular vibrating portion where a plurality of first vibrating portions and a plurality of second vibrating portions are alternately arranged on at least a part thereof, the first electrodes corresponding to the first vibrating portions and the second electrodes corresponding to the second vibrating portions are alternately arranged on a plane perpendicular to the

[001] axis of the single crystal. In this way, by adopting a structure in which a plurality of unit oscillators are arranged on at least a part of the annular vibrating portion, the phases of the vibration waves generated by each unit oscillator can be made consistent and circulate in the annular vibrating portion. Therefore, the vibration intensity can be enhanced by circulation or the like, and a high Q value can be obtained.

[0029] The vibration element of the second mode of the present invention is a mode subordinate to the first mode, and is characterized in that it includes a reflection part that reflects the vibration generated by the vibration part.

[0030] According to this mode, a reflection part is provided, and the reflection part reflects the vibration generated by the vibration part. Therefore, it is possible to easily make the phases of the vibration waves generated by each unit oscillator consistent and surround in the annular vibration part, etc.

[0031] The vibration element of the third mode of the present invention is a mode subordinate to the second mode, and is characterized in that as the reflection part, it has a first reflection part and a second reflection part. The first reflection part reflects the incident longitudinal wave into a transverse wave, and the second reflection part reflects the transverse wave incident via the first reflection part into a longitudinal wave.

[0032] According to this mode, as the reflection part, it has a first reflection part and a second reflection part. The first reflection part reflects the incident longitudinal wave into a transverse wave, and the second reflection part reflects the transverse wave incident via the first reflection part into a longitudinal wave. Therefore, it is possible to make the phases of the vibration waves generated by each unit oscillator consistent and surround while changing from a longitudinal wave to a transverse wave and from a transverse wave to a longitudinal wave in the annular vibration part.

[0033] The vibration element of the fourth mode of the present invention is a mode subordinate to the third mode, and is characterized in that as the reflection part, it has a third reflection part. The third reflection part is between the first reflection part and the second reflection part and reflects the incident transverse wave into a transverse wave.

[0034] According to this mode, as the reflection part, it has a third reflection part. The third reflection part is between the first reflection part and the second reflection part and reflects the incident transverse wave into a transverse wave. Therefore, it is possible to adjust the advancing direction of the transverse wave through the third reflection part so that it properly faces the second reflection part from the first reflection part.

[0035] The vibration element of the fifth mode of the present invention is a mode subordinate to the second mode, and is characterized in that as the reflection part, it has a fourth reflection part. The fourth reflection part reflects the incident longitudinal wave into a longitudinal wave.

[0036] According to this mode, as the reflection part, it has a fourth reflection part. The fourth reflection part reflects the incident longitudinal wave into a longitudinal wave. Therefore, it is possible to make the vibration waves generated by each unit oscillator consistent while maintaining the longitudinal wave state in the annular vibration part, so that the phases of the vibration waves generated by each unit oscillator are consistent and strengthened.

[0037] The vibration element according to the sixth aspect of the present invention is an aspect subordinate to any one of the first to fifth aspects, and is characterized by including a spacer that insulates the first connecting portion and the second connecting portion between the first connecting portion and the second connecting portion at a position where the first connecting portion and the second connecting portion overlap when viewed from a direction parallel to the

[001] axis of the single crystal.

[0038] According to this aspect, a spacer is included, and the spacer insulates the first connecting portion and the second connecting portion between the first connecting portion and the second connecting portion at a position where the first connecting portion and the second connecting portion overlap when viewed from a direction parallel to the

[001] axis of the single crystal. Therefore, a desired voltage can be stably applied to the first electrode and the second electrode.

[0039] The vibration element according to the seventh aspect of the present invention is an aspect subordinate to any one of the first to fifth aspects, and is characterized in that a plurality of the first vibration portions and a plurality of the second vibration portions are arranged in a direction parallel to the

[110] axis or the [-110] axis of the single crystal and are disposed on the piezoelectric body.

[0040] According to this aspect, a plurality of the first vibration portions and a plurality of the second vibration portions are arranged in a direction parallel to the

[110] axis or the [-110] axis of the single crystal and are disposed on the piezoelectric body. By adopting such a structure, even when a voltage is applied to each electrode particularly efficiently to vibrate the first vibration portion and the second vibration portion, it is possible to prevent the overall vibration portion from deforming in the direction in which the first vibration portion and the second vibration portion are arranged.

[0041] The vibration element according to the eighth aspect of the present invention is an aspect subordinate to any one of the first to fifth aspects, and is characterized by including a base portion and a support portion. The base portion is provided on at least a part of the periphery of the vibration portion when viewed from a direction parallel to the

[001] axis of the single crystal, and a plurality of the first vibration portions and a plurality of the second vibration portions are not disposed thereon. The support portion bridges the vibration portion and the base portion.

[0042] According to this aspect, a base portion and a support portion are included. The base portion is provided on at least a part of the periphery of the vibration portion when viewed from a direction parallel to the

[001] axis of the single crystal, and a plurality of the first vibration portions and a plurality of the second vibration portions are not disposed thereon. The support portion bridges the vibration portion and the base portion. By adopting such a structure, it is possible to appropriately arrange the vibration portion that vibrates by applying a voltage to the electrode and the base portion that does not vibrate even when a voltage is applied to the electrode.

[0043] The vibration element of the ninth aspect of the present invention is an aspect subordinate to the eighth aspect, characterized in that the support portion bridges the node of the vibration portion and the base portion.

[0044] According to this aspect, the support portion bridges the node of the vibration portion and the base portion. By adopting such a structure, it is possible to bridge the region of the vibration portion that does not vibrate even when the vibration portion vibrates by applying a voltage to the electrode and the base portion. Therefore, it is possible to achieve a mode in which the base portion does not vibrate even when a voltage is applied to the electrode.

[0045] The vibration element of the tenth aspect of the present invention is an aspect subordinate to the eighth aspect, characterized in that the support portion extends parallel to the

[110] axis of the single crystal or the [-110] axis of the single crystal.

[0046] According to this aspect, the support portion extends parallel to the

[110] axis of the single crystal or the [-110] axis of the single crystal. By adopting such a structure, it is possible to appropriately bridge the vibration portion and the base portion.

[0047] The vibration element of the eleventh aspect of the present invention is an aspect subordinate to any one of the first to fifth aspects, characterized in that the piezoelectric body is composed of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN.

[0048] According to this aspect, the piezoelectric body is composed of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN. By adopting such a structure, it is possible to provide an appropriate piezoelectric body.

[0049] Example 1

[0050] Hereinafter, with reference to Figures 1 to 9 , the vibration element 100 according to Example 1 of the present invention will be described. The vibration element 100 of this example is a piezoelectric vibration element using a piezoelectric body composed of a zinc blende single crystal. As Figure 1 shown, the vibration element 100 of this example mainly includes a vibration portion 1 that vibrates by applying a voltage, a base portion 3 that does not vibrate even when a voltage is applied, and a support portion 2 that bridges the vibration portion 1 and the base portion 3. In addition, "does not vibrate even when a voltage is applied" does not strictly mean that it does not vibrate at all, but rather means that the vibration is suppressed to a level where no adverse effects occur.

[0051] The vibrating section 1 is composed of a substrate of a zinc blende-type single crystal (space group F-43m) having a piezoelectric effect. As the zinc blende-type single crystal, for example, a cubic crystal such as a 3C-SiC single crystal can be used. The vibrating section 1 is annular, and details will be described below. On a part thereof, a plurality of first vibrating sections and a plurality of second vibrating sections are adjacent and alternately arranged in the direction of the

[110] axis of the single crystal. In addition, in Figure 1 , Figure 2 , Figure 5 , Figures 7 to 9 , and further Fig.10 in each of the drawings, the a1 axis corresponds to the

[100] axis of the single crystal, the a2 axis corresponds to the

[010] axis of the single crystal, and the a3 axis corresponds to the

[001] axis of the single crystal.

[0052] The vibrating section 1 is composed of an electrode group, two common electrodes (not shown), a longitudinal wave-transverse wave conversion section 13, and a total reflection section 14. The electrode group is formed on the surface on the

[001] axis side and includes unit electrodes 11 respectively provided corresponding to the unit oscillators 16 of the first vibrating section and the second vibrating section. The two common electrodes are formed in a region on the surface on the [00-1] axis side corresponding to the back side of the formation region of the unit electrodes 11. The structure composed of the electrode group on the surface on the

[001] axis side, the region of the common electrodes on the surface on the [00-1] axis side opposed thereto, and the region of the single crystal substrate where stress caused by the piezoelectric effect is generated when a voltage is applied between these electrodes has the function of an oscillator and constitutes the unit oscillator 16. For example, in addition to the 3C-SiC single crystal, the single crystal substrate can also use AlN, GaN, etc. belonging to the zinc blende-type single crystal (space group F-43m). As the material of the electrodes, for example, Au, Pt, Al, etc. can be used, and a layer for close adhesion and strengthening such as Ti or its compound can also be provided between these metal materials and the single crystal.

[0053] In addition, in this specification, there are cases where the arrow mark direction of the

[100] axis represents the a1 axis, the [-100] axis represents the direction opposite to the arrow mark direction of the a1 axis, and the

[100] axis represents the direction along the arrow mark direction of the a1 axis and its opposite direction. In addition, there are cases where the arrow mark direction of the

[010] axis represents the a2 axis, the [0-10] axis represents the direction opposite to the arrow mark direction of the a2 axis, and the

[010] axis represents the direction along the arrow mark direction of the a2 axis and its opposite direction. In addition, there are cases where the arrow mark direction of the

[001] axis represents the a3 axis, the [00-1] axis represents the direction opposite to the arrow mark direction of the a3 axis, and the

[001] axis represents the direction along the arrow mark direction of the a3 axis and its opposite direction.

[0054] The excitation unit 12 corresponding to the formation region of the unit electrode 11 has a structure in which the unit oscillators 16 are arranged in a matrix along the (001) plane of the cubic crystal. Specifically, a plurality of unit oscillators 16 arranged in two columns along the [-110] axis of the single crystal are arranged along the

[110] axis of the single crystal. The longitudinal wave component of the elastic wave generated by the displacement of each unit oscillator 16 and propagating in the long side direction of the excitation unit 12, that is, the

[110] axis direction of the single crystal, becomes a traveling wave. The detailed content will be described below. This traveling wave is reflected by the longitudinal wave-transverse wave conversion unit 13 and then repeatedly propagates and reflects in the total reflection unit 14, so as to surround along the annular structure of the vibrating unit 1. In addition, specifically, in addition to the traveling wave component that surrounds in one direction, there is also a traveling wave component that surrounds in the opposite direction. Therefore, these two traveling waves will interfere to generate a standing wave. According to the structure of the vibrating unit 1, the center position of this standing wave becomes a node.

[0055] As Figure 2 shown, the longitudinal wave-transverse wave conversion unit 13 has a planar end face, and this end face reflects the traveling wave of the longitudinal wave P generated by the excitation unit 12 to convert it into a transverse wave SV and reflects it in the direction of the total reflection unit 14, or converts the transverse wave SV into a longitudinal wave P and reflects it in the direction of another excitation unit 12. Here, the reflection operation of the longitudinal wave-transverse wave conversion unit 13 will be described below.

[0056] When the sound velocities of the longitudinal wave P (P wave) and the transverse wave SV (SV wave) in the crystal are represented by α and β respectively, generally, the values of α and β are different. For example, the representative values of 3C-SiC are α = 11938 m / s and β = 7608 m / s. In this case, when the longitudinal wave P is reflected by the free surface, a component of the transverse wave SV is generated and emitted at a different angle to be separated from the component of the longitudinal wave P. Similarly, when the transverse wave SV is reflected by the free surface, it is separated into a component of the transverse wave SV and a component of the longitudinal wave P. The mathematical expressions representing the reflection amplitude and phase change are shown in Table 1 below. The variables used here are shown in Equation 1 below. In Figure 3 is shown the outgoing angle Θ* of the longitudinal wave P and the outgoing angle of the transverse wave SV when the incident angle Θ of the longitudinal wave P is used as a variable, the reflection amplitude and phase change. As Figure 3 shown in the graph in the middle of, it can be seen that when the incident angle Θ of the longitudinal wave P = 46°, the reflection amplitude of the longitudinal wave P is 0, and all the vibration energy of the longitudinal wave P is converted into the transverse wave SV. As Figure 2 shown, when Θ = 46°, the outgoing angle of the transverse wave SV is different from the incident angle Θ of the longitudinal wave P. On the other hand, in Figure 4 is shown the outgoing angle Θ* of the longitudinal wave P and the outgoing angle of the transverse wave SV when the incident angle of the transverse wave SV Reflection amplitude and phase change. At the incident angle of the shear wave SV when, as shown in the graph in the middle of Figure 4 , the reflection amplitude of the shear wave SV is 0, and all the vibration energy of the shear wave SV can be converted into the longitudinal wave P.

[0057] Table 1

[0058]

[0059] Mathematical formula 1

[0060]

[0061] As shown in Figure 2 , the total reflection part 14 has the following plane, that is, a plane for totally reflecting the shear wave SV converted by reflection from the longitudinal wave-shear wave conversion part 13 and emitting it in the direction of the longitudinal wave-shear wave conversion part 13 symmetrically arranged on the incident side. As shown in Figure 4 , it can be seen that total reflection is performed at the incident angle of the shear wave SV . In addition, Figure 2 shows the path of the series of traveling waves of longitudinal wave P-shear wave SV conversion, total reflection of shear wave SV, and shear wave SV-longitudinal wave P conversion and the positional relationship of the reflection surface described so far.

[0062] Next, hereinafter, an example of the connection method of the unit electrode 11 will be described based on this embodiment. In order to obtain the enhanced vibration of the traveling wave generated by the interlocking of all the unit oscillators 16, among the unit oscillators 16 adjacent in the

[100] axis direction or

[010] axis direction, the unit electrodes 11 are connected in such a way that the application directions of the electric fields in the

[001] axis direction are antiparallel. To achieve this, all the unit electrodes belong to either the a electrode group corresponding to the first vibration part of the unit oscillators Figure 5 Figure 5 and the unit oscillator 162, or the b electrode group corresponding to the second vibration part of the unit oscillators Figure 5 Figure 5 and the unit oscillator 164 among the unit oscillators 16.

[0063] Here,[[]]END]] Figure 5 shows the pair of Figure 1The structure of the region R is magnified. The unit electrodes 111 and 112 arranged obliquely on the surface of the single crystal substrate in the unit electrode 11 belong to the a electrode group and are connected by the bridge portion 11b. On the other hand, the unit electrodes 113 and 114 in the unit electrode 11 belong to the b electrode group and are connected by the connecting portion 11c. Here, the region sandwiched by the unit electrode 111 of the vibrating portion 1 and the common electrode corresponds to the unit oscillator 161, and the region sandwiched by the unit electrode 112 of the vibrating portion 1 and the common electrode corresponds to the unit oscillator 162. Moreover, the region sandwiched by the unit electrode 113 of the vibrating portion 1 and the common electrode corresponds to the unit oscillator 163, and the region sandwiched by the unit electrode 114 of the vibrating portion 1 and the common electrode corresponds to the unit oscillator 164.

[0064] The connecting portion 11c and the bridge portion 11b are electrically insulated by the spacer 11a. As the spacer 11a, oxides such as SiO2, nitrides, resin materials, etc. can be used. By using such a cross-connection method, all the unit electrodes 11 belonging to the a electrode group are connected. On the other hand, all the unit electrodes 11 belonging to the b electrode group are also connected in the same way. As a result of such connection, on the surface of the (001) plane side of the cubic crystal of the vibrating portion 1, unit electrodes 11 with different polarities are alternately arranged, forming a so-called black-and-white checkerboard pattern configuration. In addition, the common electrode formed on the surface of the (00-1) plane, i.e., the back side of the cubic crystal of the vibrating portion 1, is connected to an unillustrated common electrode provided on the back surface of the base portion 3 via the electrode formed on the back surface of the support portion 2.

[0065] Here, the support portion 2 is a portion for holding the vibrating portion 1 at a relative position with respect to the base portion 3. As the material, the same single crystal substrate as that of the vibrating portion 1 can be used, or it can be formed by bonding other materials. In order to reduce the vibration leakage from the vibrating portion 1 to the base portion 3, it is preferable that the position connecting the support portion 2 and the vibrating portion 1 is set to a position where the displacement of the vibration of the vibrating portion 1 does not occur, i.e., the node position. In addition, in order to reduce the vibration leakage from the vibrating portion 1 to the base portion 3, it is preferable to minimize the thickness of the support portion 2 as much as possible. However, in order to suppress the breakage of the support portion 2 due to external vibration or impact, it is preferable to make the support portion 2 of an appropriate thickness to ensure the necessary strength. In addition, although in Figure 1 the support portion 2 is shown as a prismatic shape in a straight line, in order to relieve stress concentration and improve impact resistance, in addition to optimizing the length, it can also be set to a structure mixed with a curved structure or the like. In addition, in this embodiment, the electrodes are formed in a manner that closely adheres to the surface of the support portion 2, and also serve to electrically connect the vibrating portion 1 and the electrodes formed on the base portion 3.

[0066] The base portion 3 is fixed within an airtight package that surrounds the piezoelectric vibrator. As the material, the same single crystal substrate as that of the vibrating portion 1 and the supporting portion 2 can be used, or other materials can be joined to form it. On the lead electrode 5a formed on the surface of the base portion 3 shown in Figure 1 all the unit electrodes of the a - electrode group are electrically connected via the electrode formed on the surface of the supporting portion 2. On the other hand, on the Figure 1 lead electrode 5b shown in all the unit electrodes of the b - electrode group are electrically connected. In addition, in order to supply power to the vibrating portion 1, the lead electrode 5a and the lead electrode 5b are connected to an oscillation circuit (not shown) provided within the same package by wire bonding or the like.

[0067] In the vibration element 100 of the present embodiment, by applying a voltage between the unit electrode 11 and the opposed common electrode, an electric field in the

[001] - axis direction can be applied to the single crystal substrate. By this action, the single crystal of each unit vibrator 16 can perform a contour vibration operation. Specifically, it corresponds to the operation of the following vibration mode: when it expands in the

[110] - axis direction in a certain phase, it contracts in the [-110] - axis direction, and when the direction of the electric field is reversed, it contracts in the

[110] - axis direction and expands in the [-110] - axis direction. By this contour vibration operation, the same amount of expansion and contraction are simultaneously generated in different directions at a local portion within the single crystal substrate, so the volume does not change, which is advantageous from the viewpoints of thermo - elastic loss and Akhiezer loss based on phonon scattering.

[0068] Here, in Figure 6 an example of the voltage waveforms applied to the above - mentioned lead electrode 5a, lead electrode 5b, and common electrode is shown. These voltage waveforms can be generated by the above - mentioned oscillation circuit (not shown). In Figure 6 the lead electrode 5a is represented by a solid line, the lead electrode 5b is represented by a one - dot - chain line, and the common electrode is represented by a two - dot - chain line. The voltage waveforms applied to the lead electrode 5a and the lead electrode 5b are sine waves with equal amplitudes, but are shifted by a half - cycle amount, and the phase is shifted by π [rad]. The common electrode becomes the average voltage applied to the lead electrode 5a and the lead electrode 5b. As shown in Figure 6 when the signs of the applied voltages of the lead electrode 5a and the lead electrode 5b are different and the amplitudes are equal, the voltage of the common electrode becomes a fixed value.

[0069] By applying an AC voltage having a frequency at which the vibrating portion 1 resonates to the lead electrode 5a and the lead electrode 5b, a desired vibration operation can be performed. For example, in Figure 7In the figure, the displacement state of the corners of the vibration part 1 is exaggerated for ease of understanding. Here, unit electrodes belonging to the same electrode group in the electrode group a and the electrode group b are formed on the unit vibrators 16 corresponding to the same hatching. When no voltage is applied to the lead electrode 5a and the lead electrode 5b, all the unit vibrators 16 do not displace but maintain a square shape, and the same deformation is obtained by applying an electric field in the same direction. In addition, displacement occurs by applying a voltage. When the direction of voltage application is reversed after a time equivalent to half a cycle of the resonant frequency, the warping direction of the contour of each unit vibrator 16 is also reversed. That is, when the direction of voltage application is continuously and alternately reversed, the boundary surfaces of adjacent unit vibrators 16 will also become a smooth and warping-matched concave-convex relationship, and unnecessary deformation will not occur.

[0070] Similarly, by repeatedly reversing the voltage application direction according to the resonant frequency, stable and low-loss vibration can be obtained in which all unit oscillators 16 are cooperatively reinforced. This makes the phases of adjacent antinodes of the standing wave opposite, and a stable standing wave can be obtained.

[0071] Next, the appropriate crystal orientation for achieving the above-mentioned vibration operation will be described. Figure 8 The crystal structure of 3C-SiC used in the vibration element 100 of this embodiment is shown in FIG. The

[100] axis, the

[010] axis, and the

[001] axis of the single crystal are aligned with the a1 axis, the a2 axis, and the a3 axis, respectively, and the displacement when an electric field is applied is confirmed.

[0072] Generally speaking, the piezoelectric tensor e of the e-form in a crystal of the space group F-43m is described by the following formula 2.

[0073] Mathematical formula 2

[0074]

[0075] On the other hand, the piezoelectric tensor d in d form can be used to calculate the elastic compliance tensor S E That is, the following formula 3 is derived as the following formula 4.

[0076] Mathematical formula 3

[0077]

[0078] Mathematical formula 4

[0079]

[0080] Here, when an electric field E having components E1, E2, and E3 in the axial directions of the a1 axis, a2 axis, and a3 axis, respectively, is applied, the displacement tensor S can be expressed by Equation 5 below.

[0081] Mathematical Equation 5

[0082]

[0083] Here, when an electric field is applied in the axial direction of the a3 axis, only the component of E3 is non-zero. Therefore, only the component S6 of the displacement tensor S is non-zero. The defining equation for this component S6 is Equation 6 below.

[0084] Mathematical Equation 6

[0085]

[0086] Here, u1 and u2 represent the displacement amounts in the axial directions of the a1 axis and a2 axis, respectively. Next, use Figure 9 to explain how the above displacement amounts actually cause deformation of the vibration part 1. In particular, since there is no component in the axial direction of the a3 axis in the component S6, it becomes an expression in a two-dimensional plane including the a1 axis and a2 axis. First, according to Equation 5 as the defining equation, it becomes Equation 7 below, and according to Equation 7, it becomes Equation 8 below.

[0087] Mathematical Equation 7

[0088] 2S 12 =S 12 +S 21 …(Equation 7)

[0089] Mathematical Equation 8

[0090] S 12 =S 21 …(Equation 8)

[0091] Here, if it is assumed that the component S6 is positive, then S 12 and S 21 are also positive. From the defining equation, that is, the change in displacement when the S 12 component of Equation 5 only moves a small distance +Δa1 is +Δu2. Similarly, when the S 21 component moves +Δa2, the displacement amount becomes +Δu1. Then, the combined displacement is in the positive direction of the a1' axis in Figure 9 . Conversely, at the position (-Δa1, -Δa2), the displacement amounts become -Δu1 and -Δu2. Therefore, the combined displacement is in the negative direction of the a1' axis. As a result, an elongation deformation in the axial direction of the a1' axis occurs in a small region within the unit oscillator 16.

[0092] On the other hand, due to the displacement in the positive direction of the a2' axis at the position (Δa1, -Δa2) and the displacement in the negative direction of the same axis at the position (-Δa1, Δa2), a contraction deformation occurs in the axial direction of the a2' axis. Moreover, afterwards, when the direction of voltage application is reversed, the sign of the component S6 is also reversed, and the elongation direction and the contraction direction alternate.

[0093] According to the above description, by assigning the

[001] axis to the direction of the a3 axis shown, the

[110] axis to the direction of the a1' axis, and the [-110] axis to the direction of the a2' axis, the displacement required for the desired contour vibration can be obtained. Furthermore, at the points (Δa1, 0), (-Δa1, 0), (0, Δa2), and (0, -Δa2), no displacement occurs even during contour vibration, that is, they become the nodes of vibration. Therefore, when the support portion 2 is provided in this direction, the vibration leaking to the base portion 3 can be suppressed. Therefore, preferably, the support portion 2 is provided in any direction along the crystal orientations

[100] , [-100],

[010] , and [0 - 10] from the center of gravity of any unit oscillator 16. Additionally, as Figure 1 shown, the vibration element 100 of the present embodiment has such a structure. For example, on the unit oscillator 16 corresponding to the unit electrode 11, the support portion 2 is provided from its center of gravity in the [-100] direction. Figure 1 That is, in the vibration element 100 of the present embodiment, the support portion 2 bridges the nodes of the vibration portion 1 and the base portion 3. By having such a structure, the vibration element 100 of the present embodiment can bridge the region of the vibration portion 1 that does not vibrate even when the vibration portion 1 vibrates by applying a voltage to the unit electrode 11 serving as an electrode and the base portion 3. Therefore, the vibration element 100 of the present embodiment can be a vibration element in which the base portion 3 does not vibrate even when a voltage is applied to the unit electrode 11.

[0094] That is, in the vibration element 100 of the present embodiment, the support portion 2 bridges the nodes of the vibration portion 1 and the base portion 3. By having such a structure, the vibration element 100 of the present embodiment can appropriately bridge the vibration portion 1 and the base portion 3.

[0095] In addition, from another aspect, on the premise that the support portion 2 bridges the nodes of the vibration portion 1 and the base portion 3, the support portion 2 connects the four sides of the vibration portion 1, two of which extend along the

[110] axis of the single crystal, and the remaining two extend parallel to the [-110] axis of the single crystal. By having such a structure, the vibration element 100 of the present embodiment can appropriately bridge the vibration portion 1 and the base portion 3.

[0096] In addition, the above-described vibration element 100 and an oscillation circuit can be combined to form an oscillator. Moreover, they can be housed in a vacuum package to obtain a more stable oscillator. In addition, although the present embodiment has a piezoelectric body made of 3C - SiC single crystal, as long as the piezoelectric body is made of a zinc blende - type single crystal, substances other than 3C - SiC single crystal can also be used.

[0097] Here, the vibration element 100 of the present embodiment will be described from other aspects. As described above, the vibration element 100 of the present embodiment includes a vibration unit 1. The vibration unit 1 is annular, and on at least a part thereof, a plurality of first vibration units such as unit oscillators 161 and unit oscillators 162 sandwiched between an a electrode group and a common electrode, and a plurality of second vibration units such as unit oscillators 163 and unit oscillators 164 sandwiched between a b electrode group and a common electrode are alternately arranged. Moreover, the vibration unit 1 has: a first electrode corresponding to unit electrodes 111, unit electrodes 112, etc. and respectively provided on the plurality of first vibration units; a second electrode corresponding to unit electrodes 113, unit electrodes 114, etc. and respectively provided on the plurality of second vibration units; a bridge unit 11b that serves as a first connection unit and electrically connects the first electrodes to each other; and a connection unit 11c that serves as a second connection unit and electrically connects the second electrodes to each other. Moreover, the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[001] axis of the single crystal.

[0098] Thus, by adopting the structure in which a plurality of unit oscillators 16 are arranged on at least a part of the annular vibration unit 1, the vibration element 100 of the present embodiment can make the phases of the vibration waves generated by the respective unit oscillators 16 consistent and surround in the annular vibration unit 1. Therefore, the vibration element 100 of the present embodiment can enhance the vibration intensity by means of surrounding or the like, and can obtain a high Q value.

[0099] In addition, as Figure 5 shown, the vibration element 100 of the present embodiment includes a spacer 11a. When viewed from a direction parallel to the

[001] axis of the single crystal, the spacer 11a insulates the bridge unit 11b and the connection unit 11c between the bridge unit 11b and the connection unit 11c at a position where the bridge unit 11b and the connection unit 11c overlap. Therefore, a structure is formed in which a desired voltage can be stably applied to the first electrode and the second electrode.

[0100] In addition, as described above, the vibration element 100 of the present embodiment includes a longitudinal wave - transverse wave conversion unit 13 and a total reflection unit 14 that serve as reflection units and reflect the vibration generated by the vibration unit 1. Therefore, the vibration element 100 of the present embodiment can easily make the phases of the vibration waves generated by the respective unit oscillators 16 consistent and surround in the annular vibration unit 1.

[0101] Specifically, as Figure 2As shown, as the longitudinal wave - transverse wave conversion unit 13, it has a first reflection unit on the left side that reflects the incident longitudinal wave P into a transverse wave SV, and a second reflection unit on the right side that reflects the transverse wave SV incident via the first reflection unit into a longitudinal wave P. That is, as the reflection unit, the vibration element 100 of this embodiment has a first reflection unit that reflects the incident longitudinal wave P into a transverse wave SV, and a second reflection unit that reflects the transverse wave SV incident via the first reflection unit into a longitudinal wave P. Therefore, the vibration element 100 of this embodiment can change from the longitudinal wave P to the transverse wave SV and from the transverse wave SV to the longitudinal wave P in the annular vibration unit 1, while making the phases of the vibration waves generated by each unit oscillator 16 consistent and circular.

[0102] In addition, as Figure 2 shown, as the reflection unit, the vibration element 100 of this embodiment has a total reflection unit 14 as the third reflection unit between the first reflection unit and the second reflection unit, which reflects the incident transverse wave SV into the transverse wave SV. Therefore, the vibration element 100 of this embodiment has a structure that can adjust the advancing direction of the transverse wave SV through the total reflection unit 14 as the third reflection unit so that it properly faces the second reflection unit from the first reflection unit.

[0103] Furthermore, in the vibration element 100 of this embodiment, a plurality of first vibration units and a plurality of second vibration units are arranged parallel to the

[110] axis of the single crystal and disposed in the piezoelectric body. By having such a structure, the vibration element 100 of this embodiment can be in a form where the overall vibration unit does not deform in the direction in which the first vibration unit and the second vibration unit are arranged, even when voltage is applied to each unit electrode 11 particularly efficiently to vibrate the first vibration unit and the second vibration unit. In addition, in this embodiment, a plurality of first vibration units and a plurality of second vibration units are arranged parallel to the

[110] axis of the single crystal and disposed in the piezoelectric body, and the same effect can also be obtained in a structure where a plurality of first vibration units and a plurality of second vibration units are arranged parallel to the [-110] axis of the single crystal and disposed in the piezoelectric body.

[0104] Moreover, the vibration element 100 of this embodiment includes a base portion 3 and a support portion 2. The base portion 3 is provided at least partially around the vibration unit 1 when observed from a direction parallel to the

[001] axis of the single crystal and does not have a plurality of first vibration units and a plurality of second vibration units arranged therein, and the support portion 2 bridges the vibration unit 1 and the base portion 3. By having such a structure, the vibration element 100 of this embodiment can appropriately arrange the vibration unit 1 that vibrates by applying voltage to the unit electrode 11 and the base portion 3 that does not vibrate even when voltage is applied to the unit electrode 11.

[0105] In addition, as long as the piezoelectric body is composed of a single crystal of the sphalerite type, the structural material of the piezoelectric body is not particularly limited, and the piezoelectric body is preferably composed of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN. By adopting such a structure, an appropriate piezoelectric body can be obtained.

[0106] As described above, by arranging a plurality of unit oscillators 16 operating in the contour vibration mode in a ring shape, the phases of the elastic waves generated from each unit oscillator 16 are made consistent and surround, so that an enhanced single vibration mode can be obtained, and a high Q value can be obtained. In addition, by forming two electrode groups with different polarities on the surface of the vibration part 1 and forming a common electrode on the back surface, the alignment of the front and back positions is not required during patterning, thereby improving the production efficiency. In addition, by using a sphalerite-type crystal in the single crystal substrate and setting it with an appropriate crystal orientation, a strong contour vibration can be obtained. Based on the above effects, the vibration element 100 of the present embodiment can obtain a large-amplitude and stable signal from the vibration part 1, and as a result, an oscillator with low phase noise can be obtained.

[0107] Embodiment 2

[0108] Next, Fig.10 will be used to describe the vibration element 100 of Embodiment 2. In addition, Fig.10 For the figure showing the vibration part 1, except for the parts described below, the structure is the same as that of the vibration element 100 of Embodiment 1. In Fig.10 , the same reference numerals are used to represent the structural components common to the above Embodiment 1, and the detailed description is omitted. Here, except for the parts described below, the vibration element 100 of the present embodiment has the same features as the vibration element 100 of Embodiment 1.

[0109] In the vibration element 100 of the present embodiment, unit electrodes 11 are formed on the entire surface on the (001) plane side of the cubic crystal of the vibration part 1, and a common electrode composed of a full-surface electrode is formed on the entire surface on the (00-1) plane side of the cubic crystal of the vibration part 1. By adopting such a structure, as Fig.10 shown, unit oscillators 16 are formed on the entire vibration part 1. In addition, the unit oscillators 16 are the same as those of the vibration element 100 of Embodiment 1, and a plurality of first vibration parts and a plurality of second vibration parts are alternately arranged. Moreover, by adopting such a structure, there is no reflection part or reflection surface that vertically reflects the traveling wave. However, at the corner part 15 of the vibration part 1, there are unit oscillators 16 that induce a traveling wave in the [-110] axis direction of the single crystal from the traveling wave propagating in the

[110] axis direction of the single crystal, for example, through contour vibration. Through the action of these unit oscillators 16, a surrounding traveling wave can be obtained, and stable vibration can be obtained.

[0110] Describing from other aspects, the vibration element 100 of this embodiment has the following structure, that is, as a reflection part, it has a fourth reflection part corresponding to the side of the corner part 15 and reflecting the incident longitudinal wave P into the longitudinal wave P. Therefore, the vibration element 100 of this embodiment can make the phases of the vibration waves generated by each unit oscillator 16 consistent and enhanced by keeping the state of the longitudinal wave P in the annular vibration part 1 while making the vibration waves generated by each unit oscillator 16 consistent.

[0111] Other embodiments

[0112] Next, use Figures 11 to 20 , to describe the vibration element 100 related to other embodiments of the present invention. The vibration element 100 of this embodiment is a piezoelectric vibration element using a piezoelectric body composed of a zinc blende-type single crystal. As Figure 11 shown, the vibration element 100 of this embodiment mainly consists of a vibration part 1 that vibrates by applying a voltage, a base part 3 that does not vibrate even when a voltage is applied, and a support part 2 that bridges the vibration part 1 and the base part 3. In addition, "does not vibrate even when a voltage is applied" does not mean that it does not vibrate strictly, but means that as long as the vibration is suppressed to a degree that does not cause problems.

[0113] The vibration part 1 is composed of a substrate of a zinc blende-type single crystal (space group F-43m) having a piezoelectric effect. As the zinc blende-type single crystal, for example, a crystal cut at a specified cut angle, a 3C-SiC single crystal as a cubic crystal, etc. can be used. The vibration part 1 is annular, and the details will be described below. On a part of it, a plurality of first vibration parts and a plurality of second vibration parts are adjacent and alternately arranged along the

[100] axis direction of the single crystal and the

[010] axis direction of the single crystal. In addition, in Figure 11 , Fig.12 , Figures 14 to 16 , Figures 18 to 20 each of the drawings, the a1 axis corresponds to the

[100] axis of the single crystal, the a2 axis corresponds to the

[010] axis of the single crystal, and the a3 axis corresponds to the

[001] axis of the single crystal.

[0114] The vibration part 1 is composed of an electrode group, a non-illustrated overall electrode, and a reflection part 13. Among them, the electrode group includes unit electrodes 4 composed of electrodes 4a, 4b, 4c, 4d, and 4e formed on the surface on the positive direction side of the a3 axis of the single crystal substrate having a piezoelectric effect. The overall electrode is formed on the back surface (negative direction side of the a3 axis) of the single crystal substrate. The structure composed of the electrode group on the surface of the single crystal substrate, the overall electrode on the back surface of the single crystal substrate arranged at a position overlapping with the electrode group in the a3 axis direction, and the region of the single crystal substrate that mainly generates shear stress caused by the piezoelectric effect when a voltage is applied between the electrodes on the surface and the back surface of the above single crystal substrate has the function of an oscillator. That is, this structure constitutes a unit oscillator 10.

[0115] For example, in addition to 3C-SiC single crystal, single crystals belonging to the zinc blende type (space group F-43m) such as AlN and GaN can also be used for the single crystal substrate. As the material of the electrode, for example, Au, Pt, Al, etc. can be used, and a layer for adhesion strengthening such as Ti or its compound can also be provided between these metal materials and the single crystal.

[0116] In addition, in this specification, there are cases where the arrow mark direction of the

[100] axis represents the a1 axis, the [-100] axis represents the direction opposite to the arrow mark direction of the a1 axis, and the

[100] axis represents the direction along the arrow mark direction of the a1 axis and its opposite direction. In addition, there are cases where the arrow mark direction of the

[010] axis represents the a2 axis, the [0-10] axis represents the direction opposite to the arrow mark direction of the a2 axis, and the

[010] axis represents the direction along the arrow mark direction of the a2 axis and its opposite direction. In addition, there are cases where the arrow mark direction of the

[001] axis represents the a3 axis, the [00-1] axis represents the direction opposite to the arrow mark direction of the a3 axis, and the

[001] axis represents the direction along the arrow mark direction of the a3 axis and its opposite direction.

[0117] In addition, the expression such as the

[001] axis in this specification is only a representative description. Considering the symmetry of the single crystal, there are also cases where the

[100] axis,

[010] axis, [0-10] axis, [00-1] axis, etc. are represented. Thus, even when the names of the single crystal directions are different, structures that are geometrically equivalent to the arrangement direction of the unit oscillator 10, the reflection part 13, or the extension direction of the support part 2 are included in the present invention because they are also equivalent in terms of the properties of the vibration element 100.

[0118] The excitation part 12 corresponding to the formation region of the unit electrode 4 has a structure in which the unit oscillators 10 are arranged in a matrix along the a1 - a2 plane, that is, the (001) plane of the cubic crystal. The component of the shear wave SV generated by the shear displacement of each unit oscillator 10 and propagating in the long side direction of the excitation part 12, that is, the a2 direction and elastically vibrating in the a1 - a2 plane, is a traveling wave. The detailed content will be described below. This traveling wave is totally reflected by using the reflection part 13 and is repeatedly excited and reflected, so as to surround along the annular structure of the vibration part 1. In addition, in detail, in addition to the traveling wave component that surrounds in one direction, there is also a traveling wave component that surrounds in the opposite direction. Therefore, these two traveling waves interfere to generate a standing wave. According to the structure of the vibration part 1, the center position of this standing wave becomes a node.

[0119] As Fig.12As shown, the reflecting portion 13 has a reflecting surface 13a, which is a planar end surface for reflecting the traveling wave of the shear wave SV generated by the exciting portion 12 so that it bends in the direction of the adjacent exciting portion 12 while maintaining the state of the shear wave SV. In Fig.12 , when the incident angle of the shear wave SV (incident angle ) is taken as a variable, the exit angle of the shear wave SV is set as the exit angle Here, the operation of the reflection at the reflecting portion 13 will be described below.

[0120] When the sound velocities of the longitudinal wave P (P-wave) and the shear wave SV (SV-wave) in the crystal are represented by α and β respectively, generally, the values of α and β are different. For example, the representative values of 3C-SiC are α = 11938 m / s and β = 7608 m / s. In this case, when the longitudinal wave P is reflected by the free surface, a component of the shear wave SV is generated and emitted at different angles, separating from the component of the longitudinal wave P. Similarly, when the shear wave SV is reflected by the free surface, it is separated into a component of the shear wave SV and a component of the longitudinal wave P. The mathematical expressions representing the reflection amplitude and phase change are shown in Table 1. In addition, the exit angle can be calculated using Equation 1, and the result calculated with the incident angle of the shear wave SV as a variable is shown in the Figure 13 curve graph.

[0121] Under the condition of the sound velocity, in addition to the component of the shear wave SV, there is also a case where a component of the longitudinal wave P is generated. However, as shown in the upper and middle curve graphs of Figure 13 , for example, when the incident angle is 45°, no component of the longitudinal wave P is generated, and all the vibration energy is totally reflected while maintaining the state of the shear wave SV. In addition, as shown in the formula in Table 1, this feature occurs when p defined by Equation 1 is equal to η, and does not depend on the values of α and β. In addition, a phase change of -π [rad] is received during reflection, but as shown in the lower curve graph of Figure 13 , this value changes slowly with respect to the incident angle , so it has the advantage of being less affected by dimensional errors during manufacturing. Thus, a specific reflection operation is shown when the incident angle is 45°. However, in the actual manufacture of the vibration element 100, according to the phase change and the allowable error of the exit angle at the reflecting surface 13a of the reflecting portion 13, it is preferable to make the incident angle within the range of 45° ± 1°, that is, 44° or more and 46° or less.

[0122] Next, based on this embodiment, an example of the connection method of the unit electrode 4 will be described below. In order to obtain enhanced vibration of the traveling wave generated by the interlocking of all the unit oscillators 10, among the unit oscillators 10 adjacent in the direction of the

[100] axis (a1 axis) or the

[010] axis (a2 axis), the unit electrode 4 is connected in such a way that the application directions of the electric fields in the direction of the

[001] axis (a3 axis) are antiparallel. To achieve this, all the unit electrodes belong to either the a electrode group corresponding to the first vibration part such as the unit oscillator 10a and the unit oscillator 10c among the unit oscillators 10, or the b electrode group corresponding to the second vibration part such as the unit oscillator 10b and the unit oscillator 10d among the unit oscillators 10. Fig.14 and the unit oscillator 10c, etc., and the b electrode group corresponding to the second vibration part such as the unit oscillator 10b and the unit oscillator 10d among the unit oscillators 10. Fig.14 and the unit oscillator 10d, etc.

[0123] Here, Fig.14 shows a magnified structure of the Figure 11 region R1. The electrodes 4a and 4c in the unit electrode 4 belong to the a electrode group, Figure 11 and the electrode 4e in Figure 11 also belongs to the a electrode group, and they are electrically connected to the lead electrode 5a via the connection part 16 of the a electrode group, that is, the first connection part 16A. On the other hand, Fig.14 and

[0124] the electrodes 4b and 4d in the unit electrode 4 in Fig.15 belong to the b electrode group, and they are electrically connected to the lead electrode 5b via the connection part 16 of the b electrode group, that is, the second connection part 16B. Fig.14 Also, shows a magnified structure of the electrode crossing part 11 of

[0125] In addition, Fig.16 shows an enlarged structure of the electrode crossing portion 9 of Figure 11 . In the electrode crossing portion 9, the connected portion 9c of the first connection portion 16A and the bridge portion 9b of the second connection portion 16B are electrically insulated by the spacer 9a. The spacer 9a can be made of, for example, an oxide such as SiO2, a nitride, or a resin material, just like the spacer 11a. With such a crossed connection method, the lead electrode 5a and all the unit electrodes 4 belonging to the a electrode group are connected through the first connection portion 16A. In addition, similarly, the lead electrode 5b and all the unit electrodes 4 belonging to the b electrode group are connected through the second connection portion 16B.

[0126] Here, the support portion 2 is a portion for holding the vibration portion 1 at a relative position with respect to the base portion 3. As the material, the same single crystal substrate as the vibration portion 1 can be used, or other materials can be joined to form it. In order to reduce the vibration leakage from the vibration portion 1 to the base portion 3, it is preferable that the position connecting the support portion 2 and the vibration portion 1 is set to the position of a node where the vibration displacement of the vibration portion 1 does not occur. In addition, in order to reduce the vibration leakage from the vibration portion 1 to the base portion 3, it is preferable to minimize the thickness of the support portion 2 as much as possible. However, in order to suppress the breakage of the support portion 2 due to external vibration or impact, it is preferable that the support portion 2 has an appropriate thickness to ensure the necessary strength. In addition, although the support portion 2 is shown as a prismatic shape in a straight line in Figure 11 , in order to relieve stress concentration and improve impact resistance, in addition to optimizing the length, it can also be set to a structure mixed with a bent structure or the like. In addition, in the present embodiment, the electrodes are formed in a manner that closely adheres to the surface of the support portion 2, and also serve to electrically connect the vibration portion 1 and the electrodes formed on the base portion 3.

[0127] The base portion 3 is fixed inside an airtight package that surrounds the piezoelectric oscillator. As the material, the same single crystal substrate as the vibration portion 1 and the support portion 2 can be used, or other materials can be joined to form it. On the lead electrode 5a formed on the surface of the base portion 3 shown in Figure 11 , all the unit electrodes 4 of the a electrode group are electrically connected via the electrodes formed on the surface of the support portion 2. On the other hand, on the Figure 11 shown lead electrode 5b, all the unit electrodes 4 of the b electrode group are electrically connected. In addition, in order to supply power to the vibration portion 1, the lead electrode 5a and the lead electrode 5b are connected to an unillustrated oscillation circuit provided in the same package through wire bonding or the like.

[0128] In the vibration element 100 of the present embodiment, by applying a voltage between the unit electrode 4 and the common electrode opposed thereto, an electric field in the

[001] axis direction (a3 axis direction) can be applied to the single crystal substrate. By this action, the single crystal of each unit oscillator 10 can perform a plane shear vibration action. Here, the plane shear vibration means that when an electric field corresponding to a certain phase is applied to a certain unit oscillator 10, it elongates in a specific direction and contracts in a direction orthogonal thereto, and when the direction of the electric field is reversed, it contracts in a specific direction and elongates in a direction orthogonal thereto. By this plane shear vibration action, the same amount of elongation and contraction are simultaneously generated in different directions at a local part in the single crystal substrate, so the volume does not change, which is advantageous from the viewpoints of thermoelastic loss and Akhiezer loss based on phonon scattering.

[0129] Here, in Figure 17 an example of the voltage waveforms applied to the above-mentioned lead electrodes 5a, lead electrodes 5b, and common electrode is shown. These voltage waveforms can be generated by the above-mentioned oscillation circuit (not shown). In Figure 17 the lead electrode 5a is represented by a solid line, the lead electrode 5b is represented by a one-dot chain line, and the common electrode is represented by a double-dot chain line. The voltage waveforms applied to the lead electrode 5a and the lead electrode 5b are sine waves with equal amplitudes, but are shifted by a half-cycle amount, and the phases are shifted by π [rad]. The common electrode becomes the average voltage applied to the lead electrode 5a and the lead electrode 5b. As Figure 17 described, when the signs of the applied voltages of the lead electrode 5a and the lead electrode 5b are different and the amplitudes are equal, the voltage of the common electrode becomes a fixed value.

[0130] By applying an AC voltage having a frequency at which the vibration part 1 resonates to the lead electrode 5a and the lead electrode 5b, a desired vibration action can be performed. Figure 18 The contour shapes of the respective unit oscillators 10 when no voltage is applied between the lead electrode 5a and the lead electrode 5b are shown. As Figure 18 shown, the contour shapes of the respective unit oscillators 10 at this time are square. Here, on the unit oscillators 10 hatched in the same orientation, unit electrodes 4 belonging to the same electrode group are formed. Specifically, the unit electrodes 4 hatched with a straight line extending from the upper right to the lower left correspond to the a electrode group, and the unit electrodes 4 hatched with a straight line extending from the upper left to the lower right correspond to the b electrode group.

[0131] When the relative phase of the AC voltage is 0 [rad], for example, when a positive voltage is applied between the lead electrode 5a and the lead electrode 5b, each unit oscillator 10 is Fig.19 contoured and displaced into a rhombus as shown. This is the so-called displacement called "plane shear". By alternately arranging the respective unit oscillators 10 with different displacement directions, a formation such as Fig.19 a wavy displacement distribution as indicated by the wavy line in

[0132] On the other hand, when the relative phase is π [rad], relative to Fig.19 the state shown, the applied voltage is reversed. Moreover, a negative voltage is applied between the lead electrode 5a and the lead electrode 5b, resulting in Fig. 20 the state shown, and showing a displacement distribution that is inverted relative to Fig.19 the state shown. Additionally, in Fig.19 and Fig. 20 the rhombus shape of each unit oscillator 10 is exaggeratedly shown. Even when the application direction of the voltage is continuously and alternately reversed, the boundary surfaces of adjacent unit oscillators 10 will form a smooth and warp-matching concave-convex relationship, and no unnecessary deformation will occur. Similarly, by repeatedly reversing the application direction of the voltage according to the resonance frequency, stable and low-loss vibrations in which all unit oscillators 10 are coordinated and enhanced can be obtained. Thus, the phases of adjacent wave antinodes of the standing wave are opposite, and a stable standing wave can be obtained.

[0133] Here, an explanation is given of what polarities are appropriate for the unit electrodes 4 of the two unit oscillators 10 adjacent to the reflection portion 13. As described above using Figure 13 the phase changes by -π [rad] through the reflection surface 13a of the reflection portion 13. At the same time, when converted according to the path length of the shear wave SV passing through the reflection portion 13, a phase change of -π [rad] is received from the propagation delay during this period. That is, Figure 18 the path length L1 of the shear wave SV in the unit oscillator 10 shown and the path length L2 of the shear wave SV in the reflection portion 13 located between the unit oscillators 10 are both Fig.19 the length of half the wavelength of the wavy line shown.

[0134] Therefore, a phase change of -2π [rad] occurs in the path of the shear wave SV passing through the reflection portion 13 located between the unit oscillators 10. This means that, considering the periodicity of the shear wave SV, the substantial phase change during passing through the reflection portion 13 is equal to zero. Thus, by making the unit electrodes 4 of the two unit oscillators 10 adjacent to the reflection portion 13 have different polarities, a shear wave SV that continuously undergoes phase changes can be formed. That is, as Fig.14 shown, when the electrode 4c adjacent to the reflection portion 13 belongs to the a electrode group, the electrode 4d preferably belongs to the b electrode group.

[0135] According to the structure set as above, by applying an alternating voltage to generate displacement, it is possible to induce a shear horizontal wave (SV) that travels rightward and leftward when observing the annular vibrating portion 1 in the

[001] axis direction. When the alternating current frequency coincides with the resonance frequency of the vibrating portion 1, the shear horizontal waves (SV) excited by all the unit oscillators 10 are enhanced in coordination. Moreover, thereby, a standing wave with stable performance and less loss, that is, a surface shear vibration, can be obtained.

[0136] In addition, from another aspect, on the premise that the support portion 2 bridges the node of the vibrating portion 1 and the base portion 3, the support portion 2 is connected to the four sides of the vibrating portion 1, two of which extend along the

[100] axis (a1 axis) of the single crystal, and the remaining two extend parallel to the

[010] axis (a2 axis) of the single crystal. By setting the vibrating element 100 of the present embodiment to such a structure, the vibrating portion 1 and the base portion 3 can be bridged appropriately.

[0137] In addition, the above-described vibrating element 100 and an oscillation circuit can be combined to form an oscillator. Moreover, they can be housed in a vacuum package to obtain a more stable oscillator. In addition, although the present embodiment has a piezoelectric body made of 3C-SiC single crystal, as long as the piezoelectric body is made of a zinc blende-type single crystal, substances other than 3C-SiC single crystal can also be used.

[0138] Here, the vibrating element 100 of the present embodiment will be described from another aspect. As described above, the vibrating element 100 of the present embodiment includes a vibrating portion 1 having an annular shape, and on at least a part thereof, a plurality of first vibrating portions such as unit oscillators 10a, 10c, and 10e and a plurality of second vibrating portions such as unit oscillators 10b and 10d are alternately arranged. In addition, it includes a reflecting portion 13 that reflects the incident shear horizontal wave (SV) as a shear horizontal wave (SV). Here, each first vibrating portion has first electrodes such as electrodes 4a, 4c, and 4e and a first connection portion 16A that electrically connects the first electrodes to each other, and each second vibrating portion has second electrodes such as electrodes 4b and 4d and a second connection portion 16B that electrically connects the second electrodes to each other. Moreover, the plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the

[001] axis of the single crystal, and the unit oscillators 10 of the vibrating portion 1 are arranged in a manner parallel to the

[100] axis of the single crystal and are arranged in a manner parallel to the

[010] axis of the single crystal in the piezoelectric body.

[0139] Thus, by arranging the unit oscillators 10 in the annular vibration section 1 at least parallel to the

[100] axis of a single crystal and disposing them in the piezoelectric body, or arranging them parallel to the

[010] axis of the single crystal and disposing them in the piezoelectric body, and further providing a reflecting section 13 that reflects the incident shear wave SV as a shear wave SV, it is possible to make the phases of the vibration waves generated by the respective unit oscillators 10 consistent and surround them in the annular vibration section 1. Therefore, the vibration element 100 of the present embodiment configured in this way can generate a shear wave SV and enhance the vibration intensity by making it surround, and a high Q value can be obtained.

[0140] In addition, in the vibration element 100 of the present embodiment, the reflecting section 13 is disposed between the first electrode and the second electrode. For example, as Fig.14 described, the reflecting section 13 is provided between the first electrode, i.e., electrode 4c, and the second electrode, i.e., electrode 4d. In other words, the reflecting section 13 is disposed adjacent to one of the first vibration section and the second vibration section on the side where the shear wave SV is incident, and is disposed adjacent to the other of the first vibration section and the second vibration section on the side where the shear wave SV is emitted. By adopting such a structure in the vibration element 100 of the present embodiment, it is possible to reflect the shear wave SV incident from one of the first vibration section and the second vibration section as a shear wave SV to the other of the first vibration section and the second vibration section. That is, by adopting such a structure in the vibration element 100 of the present embodiment, it is possible to easily make the phases of the vibration waves generated by the respective unit oscillators 10 consistent and surround them in the annular vibration section 1.

[0141] Here, as Figure 11 shown, in the vibration element 100 of the present embodiment, the vibration section 1 includes a first portion 1A extending along the

[100] axis of the single crystal and a second portion 1B extending along the

[010] axis of the single crystal. By adopting such a structure, it is possible to efficiently arrange a plurality of unit oscillators 10 in the annular vibration section 1 and efficiently enhance the vibration intensity.

[0142] Here, the reflecting section 13 has a reflecting surface 13a, and the reflecting surface 13a can be regarded as having a first reflecting surface that reflects the shear wave SV incident from the first portion 1A to the second portion 1B. By adopting such a structure, it is possible to efficiently reflect the shear wave SV incident from the first portion 1A to the second portion 1B as a shear wave SV through the first reflecting surface.

[0143] On the other hand, as described above, in the vibration element 100 of the present embodiment, since the transverse wave SV can be made to circulate in a right-handed and left-handed manner when observing the annular vibration part 1 in the

[001] axis direction, the reflecting surface 13a can be regarded as also serving as a second reflecting surface for reflecting the transverse wave SV incident from the second part 1B to the first part 1A. Therefore, by adopting such a structure, in addition to being able to efficiently reflect the transverse wave SV incident from the first part 1A to the second part 1B as the transverse wave SV through the first reflecting surface, it is also possible to efficiently reflect the transverse wave SV incident from the second part 1B to the first part 1A as the transverse wave SV through the second reflecting surface.

[0144] Here, preferably, the angle formed by the reflecting surface 13a and the

[100] axis of the single crystal is 44 degrees or more and 46 degrees or less. By adopting such a structure, the generation of the longitudinal wave P can be suppressed, the transverse wave SV incident from the first part 1A can be particularly efficiently reflected to the second part 1B as the transverse wave SV through the first reflecting surface, and the transverse wave SV incident from the second part 1B can be particularly efficiently reflected to the first part 1A as the transverse wave SV through the second reflecting surface.

[0145] In addition, as Fig.15 shown, the vibration element 100 of the present embodiment includes a spacer 11a that insulates the first connection part 16A and the second connection part 16B between the first connection part 16A and the second connection part 16B at the electrode crossing part 11 where the first connection part 16A and the second connection part 16B overlap when observed in a direction parallel to the

[001] axis of the single crystal. Therefore, the vibration element 100 of the present embodiment can stably apply a desired voltage to the first electrode and the second electrode.

[0146] In addition, as Fig.16 shown, the vibration element 100 of the present embodiment includes a spacer 9a that insulates the first connection part 16A and the second connection part 16B between the first connection part 16A and the second connection part 16B at the electrode crossing part 9 where the first connection part 16A and the second connection part 16B overlap when observed in a direction parallel to the

[001] axis of the single crystal. Therefore, the vibration element 100 of the present embodiment can stably apply a desired voltage to the first electrode and the second electrode.

[0147] In addition, the vibration element 100 of the present embodiment includes a base portion 3 and a support portion 2. The base portion 3 is disposed on at least a part of the periphery of the vibration portion 1 when viewed from a direction parallel to the

[001] axis of the single crystal, and does not have a plurality of first vibration portions and a plurality of second vibration portions. The support portion 2 bridges the vibration portion 1 and the base portion 3. With such a structure of the vibration element 100 of the present embodiment, the vibration portion 1 that vibrates by applying a voltage to the unit electrode 4 and the base portion 3 that does not vibrate even when a voltage is applied to the unit electrode 4 can be appropriately provided.

[0148] In addition, as long as the piezoelectric body is composed of a zinc blende-type single crystal, the structural material of the piezoelectric body is not particularly limited, but the piezoelectric body is preferably composed of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN. With such a structure, a suitable piezoelectric body can be obtained.

[0149] As described above, by arranging a plurality of unit oscillators 10 operating in the contour vibration mode in a ring shape, the phases of the elastic waves generated from each unit oscillator 10 are made consistent and circulate, so that an enhanced single vibration mode can be obtained and a high Q value can be obtained. In addition, by forming two electrode groups with different polarities on the surface of the vibration portion 1 and forming a common electrode on the back surface, position alignment between the front and back is not required during patterning, thereby improving production efficiency. In addition, by using a zinc blende-type crystal in the single crystal substrate and setting it with an appropriate crystal orientation, a strong contour vibration can be obtained. Based on the above effects, the vibration element 100 of the present embodiment can obtain a large-amplitude and stable signal from the vibration portion 1, and as a result, an oscillator with low phase noise can be obtained.

[0150] The present invention is not limited to the above-described embodiments and can be implemented by various structures without departing from its gist. For example, it can be applied to a local oscillator incorporating the vibration element 100 of each of the above embodiments, a ranging / positioning system using the local oscillator, etc., and can also be considered for application to highly sensitive MEMS sensors, etc. In order to solve part or all of the above problems, or achieve part or all of the above effects, the technical features in the embodiments corresponding to the technical features in each mode described in the Summary of the Invention can be appropriately replaced and combined. In addition, as long as the technical feature is not described as an essential technical feature in this specification, it can be appropriately deleted.

[0151] Symbol Description

[0152] 1...Vibration part; 2...Support part; 3...Base part; 5a...Lead electrode; 5b...Lead electrode; 11...Unit electrode; 11a...Spacer; 11b...Bridge part (first connection part); 11c...Connected part (second connection part); 12...Excitation part; 13...Longitudinal wave - transverse wave conversion part (reflection part, first reflection part, second reflection part); 14...Total reflection part (reflection part, third reflection part); 15...Corner part (fourth reflection part); 16...Unit oscillator; 100...Vibration element; 111...Unit electrode (first electrode); 112...Unit electrode (first electrode); 113...Unit electrode (second electrode); 114...Unit electrode (second electrode); 161...Unit oscillator (first vibration part); 162...Unit oscillator (first vibration part); 163...Unit oscillator (second vibration part); 164...Unit oscillator (second vibration part); P...Longitudinal wave; SV...Transverse wave.

Claims

1. A vibration element, characterized in that, A piezoelectric body composed of a single crystal of the sphalerite type is used. The vibration element includes a vibration portion, the vibration portion being annular, and a plurality of first vibration portions and a plurality of second vibration portions being alternately arranged on at least a part thereof. The vibration portion has: first electrodes respectively provided on the plurality of first vibration portions; second electrodes respectively provided on the plurality of second vibration portions; a first connection portion that electrically connects the first electrodes to each other; and a second connection portion that electrically connects the second electrodes to each other. The plurality of first electrodes and the plurality of second electrodes are alternately arranged on a plane perpendicular to the [001] axis of the single crystal.

2. The vibration element according to claim 1, wherein a reflection portion is provided, and the reflection portion reflects the vibration generated by the vibration portion.

3. The vibration element according to claim 2, wherein as the reflection portion, there are a first reflection portion and a second reflection portion. The first reflection portion reflects the incident longitudinal wave as a transverse wave. The second reflection portion reflects the transverse wave incident via the first reflection portion as a longitudinal wave.

4. The vibration element according to claim 3, wherein as the reflection portion, there is a third reflection portion. The third reflection portion is between the first reflection portion and the second reflection portion, and reflects the incident transverse wave as a transverse wave.

5. The vibration element according to claim 2, wherein as the reflection portion, there is a fourth reflection portion. The fourth reflection portion reflects the incident longitudinal wave as a longitudinal wave.

6. The vibration element according to any one of claims 1 to 5, wherein a spacer is provided, and when observed from a direction parallel to the [001] axis of the single crystal, at a position where the first connection portion and the second connection portion overlap, the spacer insulates the first connection portion and the second connection portion between the first connection portion and the second connection portion.

7. The vibration element according to any one of claims 1 to 5, wherein the plurality of first vibration portions and the plurality of second vibration portions are arranged and disposed on the piezoelectric body in a manner parallel to the [110] axis or the [-110] axis of the single crystal.

8. The vibration element according to any one of claims 1 to 5, wherein a base portion and a support portion are provided. The base portion is provided on at least a part of the periphery of the vibration portion when observed from a direction parallel to the [001] axis of the single crystal, and the plurality of first vibration portions and the plurality of second vibration portions are not arranged thereon. The support portion bridges the vibration portion and the base portion.

9. The vibration element according to claim 8, wherein the support portion bridges the node of the vibration portion and the base portion.

10. The vibration element according to claim 8, wherein the support portion extends parallel to the [110] axis or the [-110] axis of the single crystal.

11. The vibration element according to claim 1, wherein a reflection portion is provided, and the reflection portion reflects the incident transverse wave as a transverse wave. The plurality of first vibration parts and the plurality of second vibration parts constitute a unit oscillator. In the vibration part, the unit oscillator is arranged and disposed in the piezoelectric body at least in a manner parallel to the [100] axis of the single crystal, or arranged and disposed in the piezoelectric body in a manner parallel to the [010] axis of the single crystal.

12. The vibration element according to claim 11, wherein: The reflection part is disposed adjacent to one of the first vibration part and the second vibration part on the incident shear wave side, and is disposed adjacent to the other of the first vibration part and the second vibration part on the outgoing shear wave side.

13. The vibration element according to claim 11, wherein: The vibration part includes a first part extending along the [100] axis of the single crystal and a second part extending along the [010] axis of the single crystal.

14. The vibration element according to claim 13, wherein: The reflection part includes a first reflection surface that reflects the shear wave incident from the first part.

15. The vibration element according to claim 14, wherein: The angle formed by the first reflection surface and the [100] axis of the single crystal is 44 degrees or more and 46 degrees or less.

16. The vibration element according to any one of claims 11 to 15, wherein: A spacer is provided, and when viewed from a direction parallel to the [001] axis of the single crystal, at a position where the first connection part and the second connection part overlap, the spacer insulates the first connection part and the second connection part between the first connection part and the second connection part.

17. The vibration element according to any one of claims 11 to 15, wherein: A base part and a support part are provided. The base part is disposed on at least a part of the periphery of the vibration part when viewed from a direction parallel to the [001] axis of the single crystal, and does not have a plurality of the first vibration parts and a plurality of the second vibration parts disposed thereon. The support part bridges the vibration part and the base part.

18. The vibration element according to claim 17, wherein: The support part bridges a node of the vibration part and the base part.

19. The vibration element according to claim 17, wherein: The support part extends and is disposed parallel to the [100] axis or the [010] axis of the single crystal.

20. The vibration element according to claim 1, wherein: The piezoelectric body is made of any one of SiC, GaN, GaAs, ZnS, CdS, and AlN.

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