Resonator and resonant device

Abstract

The present invention provides a resonator and a resonant device, which can further improve the sealing property of vibration. The resonator (10) comprises: a vibration part (120), comprising a Si substrate (F2) having a main surface on one side with a width (W) in the X-axis direction and a length (L) in the Y-axis direction, and vibrating with contour vibration as the main vibration; a holding part (140) formed to surround at least a part of the vibration part (120); and a support arm (111) extending along the Y-axis direction and connecting the holding part (140) to one end of the vibration part (120) in the Y-axis direction. When the main surface on one side is viewed from above, the width (W) of the vibration part (120) in the X-axis direction decreases from a position in the Y-axis direction at which it reaches a maximum value (Wmax) toward one end, and decreases from this position toward the other end in the Y-axis direction.

Description

Technical Field

[0001] The present invention relates to a resonator and a resonant device that vibrates in a contour vibration mode. Background Art

[0002] Conventionally, resonant devices using MEMS (Micro Electro Mechanical Systems) technology have been used, for example, as timing devices. These resonant devices are mounted on printed circuit boards (PCBs) incorporated into electronic devices such as smartphones. The resonant device comprises a lower substrate, an upper substrate forming a cavity between the lower and upper substrates, and a resonator positioned within the cavity between the lower and upper substrates.

[0003] For example, Patent Document 1 discloses a vibrating body utilizing a width expansion mode. The vibrating body has a resonating portion, the resonating portion including a rectangular piezoelectric body and a plurality of resonant electrodes formed on the outer surface of the piezoelectric body. When the length of the short side of a pair of rectangular surfaces on both sides of the polarization direction of the piezoelectric body is set to a, the length of the long side is set to b, and the Poisson's ratio of the material constituting the piezoelectric body is set to σ, the ratio b / a of the length of the long side to the short side is within a range of ±10% centered on a specified value. When an AC voltage is applied between the plurality of resonant electrodes, a width expansion mode with the short side direction as the width direction is excited.

[0004] Patent Document 1: Japanese Patent No. 3139274

[0005] As described in Patent Document 1, in a resonator whose vibrating portion has a rectangular shape when viewed from above, the center portion of the short side of the rectangle serves as a vibration node region with small displacement. Therefore, conventional resonators are provided with a support portion connecting the resonator to the holding portion in this node region, thereby suppressing leakage of vibration from the vibrating portion through the support portion to the holding portion.

[0006] However, the node region of the vibrating part may have a large strain even with a small displacement. In this case, the vibration energy of the vibrating part may leak from the supporting part to the holding part due to the strain in the node region, so there is a limit to improving the vibration containment. Summary of the Invention

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resonator and a resonant device capable of further improving the sealing properties of vibrations.

[0008] A resonator according to one aspect of the present invention comprises: a vibrating portion, comprising a substrate having a first main surface having a width in a first direction and a length in a second direction, and vibrating mainly by contour vibration; a holding portion formed to surround at least a portion of the vibrating portion; and a supporting portion extending along the second direction and connecting the holding portion to one end portion of the vibrating portion in the second direction, wherein, when the first main surface is viewed from above, the width of the vibrating portion in the first direction decreases from a position in the second direction where it is largest toward one end portion, and further decreases from this position toward the other end portion in the second direction.

[0009] A resonance device according to one aspect of the present invention includes the above-described resonator and a lid.

[0010] According to the present invention, the vibration containment performance can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view schematically showing the appearance of the resonance device in the first embodiment.

[0012] Figure 2 It simply means Figure 1 An exploded perspective view of the structure of the resonant device shown.

[0013] Figure 3 It simply means Figure 2 A top view of the resonator configuration is shown.

[0014] Figure 4 is a brief expression along Figure 3 The structure of the cross section taken along line IV-IV is shown in FIG.

[0015] Figure 5 is a brief expression along Figure 3 The structure of the cross section taken along line VV is shown in FIG.

[0016] Figure 6 It is schematically represented Figure 3 A top view showing the vibration mode of the vibration part shown.

[0017] Figure 7 It is schematically represented Figure 3 A top view showing the vibration mode of the vibration part shown.

[0018] Figure 8 It is a schematic representation based on Figure 3 A perspective view of the displacement distribution of the vibration portion shown.

[0019] Figure 9 It is a schematic representation based on Figure 3 A three-dimensional diagram showing the strain distribution of the vibration portion.

[0020] Figure 10 Yes Figure 3 A top view of a modified example of the resonator shown.

[0021] Figure 11 It is a plan view schematically showing the structure of the resonator in the second embodiment.

[0022] Figure 12 It is schematically represented Figure 11 A top view showing the vibration mode of the vibration part shown.

[0023] Figure 13 It is schematically represented Figure 11 A top view showing the vibration mode of the vibration part shown.

[0024] Figure 14 It is a schematic representation based on Figure 11 A perspective view of the displacement distribution of the vibration portion shown.

[0025] Figure 15 It is a schematic representation based on Figure 11 A three-dimensional diagram showing the strain distribution of the vibration portion.

[0026] Figure 16 This is a plan view schematically showing the structure of a resonator in the first example of the third embodiment.

[0027] Figure 17 This is a plan view schematically showing the structure of a resonator in the second example of the third embodiment. DETAILED DESCRIPTION

[0028] The following describes an embodiment of the present invention. In the following drawings, identical or similar components are represented by identical or similar reference numerals. The drawings are examples, and the sizes and shapes of the various parts are schematic and should not be construed as limiting the technical scope of the present invention to these embodiments.

[0029] [First embodiment]

[0030] First, refer to Figure 1 and Figure 2 A schematic configuration of a resonance device according to a first embodiment of the present invention will be described. Figure 1 It is a perspective view schematically showing the appearance of the resonance device 1 according to the first embodiment. Figure 2 It simply means Figure 1 The structure of the resonance device 1 is shown in an exploded perspective view.

[0031] Resonance device 1 includes resonator 10, lower cover 20, and upper cover 30. Specifically, resonance device 1 is constructed by sequentially stacking lower cover 20, resonator 10, and upper cover 30. Lower cover 20 and upper cover 30 are examples of "covers" in the present invention.

[0032] Hereinafter, each structure of the resonant device 1 will be described. In the following description, the side of the resonant device 1 where the upper cover 30 is provided is referred to as the upper side (or front), and the side where the lower cover 20 is provided is referred to as the lower side (or back).

[0033] Resonator 10 is a MEMS vibrator manufactured using MEMS technology. Resonator 10 is bonded to lower cover 20 and upper cover 30. Furthermore, resonator 10, lower cover 20, and upper cover 30 are each formed using a silicon (Si) substrate (hereinafter referred to as a "Si substrate"), and the Si substrates are bonded to each other. Alternatively, resonator 10 and lower cover 20 may be formed using an SOI substrate.

[0034] The upper cover 30 extends along the XY plane into a flat plate shape. A flat rectangular recess 31, for example, is formed on its back surface. The recess 31 is surrounded by sidewalls 33 and forms a portion of the vibration space within which the resonator 10 vibrates. Alternatively, the upper cover 30 may have a flat plate-like structure without the recess 31. Furthermore, a gettering layer may be formed on the surface of the recess 31 of the upper cover 30 facing the resonator 10.

[0035] The lower cover 20 has a rectangular flat plate-shaped bottom plate 22 arranged along the XY plane, and side walls 23 extending from the peripheral edge of the bottom plate 22 in the Z-axis direction, that is, the direction in which the lower cover 20 and the resonator 10 are stacked. In the lower cover 20, a recess 21 is formed on the surface facing the resonator 10, formed by the surface of the bottom plate 22 and the inner surface of the side wall 23. The recess 21 forms a portion of the vibration space of the resonator 10. Alternatively, the lower cover 20 may have a flat plate-shaped structure without the recess 21. Furthermore, an air gettering layer may be formed on the surface of the recess 21 of the lower cover 20 facing the resonator 10.

[0036] The vibration space of the resonator 10 is hermetically sealed and maintained in a vacuum state by the upper cover 30 and the lower cover 20. Alternatively, the vibration space may be filled with a gas such as an inert gas.

[0037] Next, refer to Figure 3 A schematic structure of a resonator according to a first embodiment of the present invention will be described. Figure 3 It simply means Figure 2 A top view of the structure of the resonator 10 is shown.

[0038] like Figure 3As shown, the resonator 10 is a MEMS vibrator manufactured using MEMS technology. The resonator 10 includes a vibrating portion 120, a holding portion 140, and a support arm 111. The support arm 111 is an example of a "support portion" in the present invention.

[0039] The vibration portion 120 includes a silicon (Si) substrate (hereinafter referred to as "Si substrate") F2, which is described later and has a main surface (the surface opposite to the upper cover 30) on one side having a width W in the X-axis direction and a length L in the Y-axis direction. In addition, as described later, the vibration portion 120 is configured to vibrate with contour vibration as the main vibration. In addition, the outer shape of the Si substrate F2 is the same as or substantially the same as the outer shape of the vibration portion 120. Therefore, in the following description, except for the cases where it is specifically stated, the vibration portion 120, when viewed from above, has a width W in the X-axis direction and a length L in the Y-axis direction, similar to the main surface of one side of the Si substrate F2.

[0040] The vibration part 120 has a shape along the direction of the upper cover 30 when viewed from above. Figure 3 The egg-shaped outline of the XY plane in the orthogonal coordinate system shown in FIG. The vibrating portion 120 is provided inside the holding portion 140 , and a space is formed between the vibrating portion 120 and the holding portion 140 at a predetermined interval.

[0041] like Figure 3 As shown, when viewed from above, the vibration portion 120 has a shape that is a combination of two semi-ovals, with the minor diameter of one semi-oval joined to the major diameter of the other semi-oval. Furthermore, the vibration portion 120 is not limited to being formed by joining or connecting two components each having a semi-oval shape; it may also be formed from a single component. In this case, the shape of the vibration portion 120 is formed by microfabrication using MEMS technology.

[0042] The length L of one semi-ellipse portion of the vibrating unit 120 along the Y-axis direction has a maximum value L1max at a position passing through the major axis of the ellipse. The length L of the other semi-ellipse portion of the vibrating unit 120 along the Y-axis direction has a maximum value L2max at a position passing through the minor axis of the ellipse.

[0043] The width W of the vibrating portion 120 along the X-axis direction has a maximum value Wmax at a position in the Y-axis direction that passes through the boundary between one semi-ellipse and the other semi-ellipse. The width W of the vibrating portion 120 along the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward one end portion in the Y-axis direction ( Figure 3 The width W in the X-axis direction becomes smaller and smaller, and moves from the Y-axis direction position where the width W in the X-axis direction becomes the maximum value Wmax toward the other end in the Y-axis direction ( Figure 3Thus, a node region of contour vibration with small displacement can be formed at one end of the vibration part 120, and a region with small strain caused by contour vibration can be formed.

[0044] like Figure 3 As shown in FIG. 1 , the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax is offset from the center line CL2 passing through the center of the vibration unit 120 in the Y-axis direction. More specifically, this position is offset from the center line CL2 in the Y-axis direction of the vibration unit 120 toward one end side of the vibration unit 120 in the Y-axis direction ( Figure 3 Offset on the negative Y-axis.

[0045] In this embodiment, the maximum value L1max of the length L in the Y-axis direction of one semi-ellipse is set to 0.9 times the maximum value Wmax of the width W in the X-axis direction. Furthermore, the maximum value L2max of the length L in the Y-axis direction of the other semi-ellipse is set to 0.25 times the maximum value Wmax of the width W in the X-axis direction. The maximum value Wmax of the width W in the X-axis direction is, for example, approximately 160 μm. Thus, in the vibrating portion 120, the length L in the Y-axis direction is greater than the width W in the X-axis direction, resulting in a long, strip-like shape in the Y-axis direction.

[0046] Furthermore, a protective film 125 is formed on the surface of the vibration portion 120 (the surface facing the upper cover 30 ) so as to cover the entire surface. The details of the protective film 125 will be described later.

[0047] The holding portion 140 is formed into a rectangular frame shape so as to surround the outer side of the vibrating portion 120 along the XY plane. Furthermore, the holding portion 140 is not limited to a frame shape, as long as it surrounds at least a portion of the vibrating portion 120. For example, the holding portion 140 may be provided around the vibrating portion 120 to a sufficient extent to hold the vibrating portion 120 and to engage with the upper cover 30 and the lower cover 20.

[0048] In this embodiment, the holding portion 140 includes integrally formed prism-shaped frames 140a to 140d. Figure 3 As shown, the frames 140a and 140b are disposed opposite the short sides of the vibration unit 120, with their long sides parallel to the X-axis. Furthermore, the frames 140c and 140d are disposed opposite the long sides of the vibration unit 120, with their long sides parallel to the Y-axis, and their ends are connected to the ends of the frames 140a and 140b, respectively.

[0049] The support arm 111 is provided inside the holding portion 140. The longitudinal direction of the support arm 111 extends along the Y axis. The support arm 111 connects the vibrating portion 120 and the holding portion 140. More specifically, the support arm 111 has one end ( Figure 3The lower end) is connected to the frame 140b, and the other end ( Figure 3 The upper and middle end) and one end of the vibration part 120 in the Y-axis direction ( Figure 3 More specifically, the other end of the support arm 111 is connected to the center of one end of the vibration part 120 in the X-axis direction. Figure 3 As shown, the support arm 111 is formed substantially plane-symmetrically with respect to a virtual plane defined parallel to the YZ plane and along the center line CL1 of the vibrating portion 120 in the X-axis direction.

[0050] In this embodiment, the example of one supporting arm 111 is shown, but the present invention is not limited thereto. As long as the supporting arm 111 is connected to one end of the vibrating portion 120 to cantilever the vibrating portion 120 and is held by the holding portion 140 , for example, two or more supporting arms 111 may be provided.

[0051] Next, refer to Figures 4 and 5 The stacked structure of the resonator according to the first embodiment of the present invention will be described. Figure 4 is a brief expression along Figure 3 The structure of the cross section taken along line IV-IV is shown in FIG. Figure 5 is a brief expression along Figure 3 The structure of the cross section taken along line VV is shown in FIG.

[0052] The vibrating portion 120, the holding portion 140, and the supporting arm 111 in the resonator 10 are integrally formed by the same process. Figure 4 As shown, the vibrating portion 120 in the resonator 10 is formed by laminating a metal layer E2 on one principal surface, i.e., the upper surface, of a Si substrate F2 having a thickness of approximately 24 μm. A piezoelectric thin film F3 is then laminated on the metal layer E2 to cover the metal layer E2, and a metal layer E1 is further laminated on the piezoelectric thin film F3. Furthermore, a protective film 125 is laminated on the metal layer E1 to cover the metal layer E1. The Si substrate F2 is an example of a "substrate" in the present invention, and the piezoelectric thin film F3 is an example of a "piezoelectric layer" in the present invention. The upper surface of the Si substrate F2 is an example of a "first principal surface" in the present invention.

[0053] The vibration part 120 includes a Si substrate F2. Figure 3 As shown, the upper surface of the Si substrate F2 has a width W along the X-axis direction and a length Y along the Y-axis direction.

[0054] As described above, the material of the substrate of the vibration part 120 is silicon (Si), whereby the mechanical strength of the vibration part 120 can be improved.

[0055] Si substrate F2 can also be formed from a degenerate n-type silicon (Si) semiconductor. Degenerate silicon (Si) can contain phosphorus (P), arsenic (As), antimony (Sb), or the like as an n-type dopant. The resistance of the degenerate silicon (Si) used in Si substrate F2 is, for example, less than 16 mΩ·cm, and more preferably less than 1.2 mΩ·cm.

[0056] As described above, by using degenerate silicon (Si) as the material of the substrate of the vibration part 120 , the frequency-temperature characteristics of the vibration part 120 can be improved.

[0057] Furthermore, a modified layer F1 is formed on the other main surface of the Si substrate F2, that is, the lower surface opposite the upper surface of the one main surface. The modified layer F1 has a thickness of approximately 0.5 μm and is formed, for example, using silicon oxide (SiO2). The lower surface of the Si substrate F2 is an example of the "second main surface" of the present invention.

[0058] In this embodiment, the correction layer F1 is a layer that has the function of reducing the temperature coefficient of the frequency of the vibrating portion 120, or the rate of change per unit temperature, when the correction layer F1 is formed on the Si substrate F2, at least at room temperature, compared to a case where the correction layer F1 is not formed on the Si substrate F2. The inclusion of the correction layer F1 in the vibrating portion 120 can, for example, reduce temperature-dependent changes in the resonant frequency of the stacked structure comprising the Si substrate F2, the metal layer E1, the piezoelectric thin film F3, and the correction layer F1, thereby improving the temperature characteristics of the vibrating portion 120.

[0059] Furthermore, the vibration unit 120 includes a metal layer E1 and a piezoelectric thin film F3 disposed between the Si substrate F2 and the metal layer E1. This facilitates the realization of a piezoelectric resonator. The vibration unit 120 also includes a metal layer E2 disposed between the Si substrate F2 and the piezoelectric thin film F3. This facilitates the realization of a piezoelectric resonator. Furthermore, the metal layer E1 is an example of the "first electrode" of the present invention, and the metal layer E2 is an example of the "second electrode" of the present invention.

[0060] The metal layers E1 and E2 have a thickness of, for example, approximately 0.2 μm or less. After film formation, they are patterned into a desired shape by etching or the like. Metal layers E1 and E2 are formed using a metal having a body-centered cubic crystal structure. Specifically, metal layer E1 is formed using molybdenum (Mo), tungsten (W), or the like.

[0061] The metal layer E1 has a shape that follows the contour of the vibration unit 120. In a plan view, the length of the metal layer E1 along the Y-axis direction is substantially the same as the length L of the vibration unit 120 in the Y-axis direction, and the width of the metal layer E1 along the X-axis direction is substantially the same as the width W of the vibration unit 120 in the X-axis direction. The metal layer E1 is not limited to a shape that follows the contour of the vibration unit 120; it may be formed from one end of the vibration unit 120 to the other end in the Y-axis direction.

[0062] The metal layer E1 is formed, for example, to function as an upper electrode on the vibration portion 120 . Furthermore, the metal layer E1 is formed on the support arm 111 and the holding portion 140 to function as wiring for connecting the upper electrode to an AC power source provided outside the resonator 10 .

[0063] On the other hand, the metal layer E2 is formed to function as a lower electrode on the vibration portion 120. Furthermore, the metal layer E2 is formed on the support arm 111 and the holding portion 140 to function as wiring for connecting the lower electrode to a circuit provided outside the resonator 10.

[0064] In addition, the Si substrate F2 itself can also serve as the lower electrode, and the metal layer E2 can be omitted.

[0065] The piezoelectric film F3 is a piezoelectric film that converts an applied voltage into vibration. The piezoelectric film F3 is formed from a material having a wurtzite hexagonal crystal structure. For example, it can be composed mainly of nitrides or oxides such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), and indium nitride (InN). Scandium aluminum nitride is a material in which part of the aluminum in aluminum nitride is replaced with scandium. Alternatively, scandium can be replaced with two elements such as magnesium (Mg) and niobium (Nb), or magnesium (Mg) and zirconium (Zr). The piezoelectric film F3 has a thickness of, for example, 0.8 μm, but a thickness of approximately 0.2 μm to 2 μm can also be used.

[0066] Furthermore, the piezoelectric film F3 is oriented along the c-axis, that is, the thickness direction (Z-axis direction) of the Si substrate F2.

[0067] Protective film 125 is formed of, for example, piezoelectric films such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), and indium nitride (InN), as well as insulating films such as silicon nitride (SiN), silicon oxide (SiO2), and aluminum oxide (Al2O3). The thickness of protective film 125 is, for example, approximately 0.2 μm. The inclusion of protective film 125 in vibrating portion 120 prevents oxidation of metal layer E1, which serves as the upper electrode for piezoelectric vibration.

[0068] The vibration portion 120 has a vibration region corresponding to the metal layer E1 serving as the upper electrode. Figure 4 As shown, within the vibration region, the piezoelectric film F3 expands and contracts in the in-plane direction of the XY plane in response to the electric field applied to it by the metal layers E1 and E2. Specifically, because the piezoelectric film F3 is oriented along its thickness, when a predetermined electric field is applied to the metal layers E1 and E2, creating a predetermined potential difference between them, the piezoelectric film F3 vibrates contoured in the in-plane direction of the XY plane in response to this potential difference. In other words, within the vibration region of the vibrating portion 120, vibrations occur that alternate between contraction and expansion of the vibrating portion 120 in both the width direction (X-axis direction) and the longitudinal direction (Y-axis direction).

[0069] In this specification, “contour vibration” is used as a general term for extension vibration, width extension vibration of dimensional change in the width direction (X-axis direction), and stretching vibration of stretching in the longitudinal direction (Y-axis direction).

[0070] Next, refer to Figure 6 and Figure 7 The displacement caused by the vibration of the vibrating part is described. Figure 6 and Figure 7 In the embodiment, it is described that the vibration part 120 does not include Figure 4 and Figure 5 The metal layer E2 shown includes a correction layer F1 with a thickness of 0.5 μm, a Si substrate F2 with a thickness of 24 μm, a piezoelectric film F3 with a thickness of 0.8 μm, a metal layer E1 with a thickness of 0.2 μm, and a protective film 125 with a thickness of 0.2 μm. Figure 6 and Figure 7 It is schematically represented Figure 3 FIG. 1 is a top view of the vibration mode of the vibration part 120 shown in FIG. Figure 6 and Figure 7 In the illustrated vibration portion 120 , a light-colored area indicates a large displacement, and a dark-colored area indicates a small displacement.

[0071] like Figure 6 As shown in FIG. 1 , in some cases, the vibration portion 120 is in a contracted state in the XY plane. Specifically, Figure 6 The three parts indicated by black arrows in FIG. 1 are greatly displaced in the direction of contraction toward the central part of the vibration part 120. At this time, the central part of the vibration part 120 and one end of the vibration part 120 connected to the support arm 111 ( Figure 6 The displacement of the middle and lower ends becomes smaller.

[0072] In addition, in other cases, such as Figure 7 As shown in FIG. 1 , the vibration portion 120 is in an expanded state in the XY plane. Figure 7 The three parts indicated by black arrows in FIG. 1 are greatly displaced in the direction of expansion from the central part of the vibration part 120. At this time, the central part of the vibration part 120 and one end part of the vibration part 120 connected to the support arm 111 ( Figure 7 The displacement of the middle and lower ends becomes smaller.

[0073] Next, refer to Figure 8 and Figure 9 The displacement distribution and strain distribution based on the vibration of the vibration part are described. Figure 8 and Figure 9 The stacked structure of the vibration part 120 and the above-mentioned Figure 6 and Figure 7 The stacked structure of the vibration part 120 is the same. Figure 8 It is a schematic representation based on Figure 3 3D diagram showing the displacement distribution of the vibration portion 120. Figure 9 It is a schematic representation based on Figure 3 The three-dimensional diagram of the strain distribution of the vibration of the vibration part 120 is shown. Figure 8 In the vibration part 120 shown in FIG. 1 , the light-colored area indicates a large displacement, and the dark-colored area indicates a small displacement. Figure 9 In the illustrated vibration portion 120 , a light-colored area indicates a large strain, and a dark-colored area indicates a small strain.

[0074] like Figure 8 As shown, in the vibration part 120, Figure 6 and Figure 7 The displacement of the three regions indicated by black arrows in the figure becomes larger. On the other hand, the displacement of the central portion of the vibration part 120 and one end portion of the vibration part 120 where the support arm 111 is provided becomes smaller.

[0075] like Figure 9 As shown in FIG. 1 , the strain in the center of the vibration part 120 becomes larger. Figure 6 and Figure 7 The strain in the three regions indicated by black arrows and one end portion of the vibration portion 120 provided with the support arm 111 becomes smaller. That is, one end portion of the vibration portion 120 becomes a region with small displacement and small strain. Figure 3 As shown, when viewing the top surface of the vibrating portion 120 from above, the width W in the X-axis direction gradually decreases from a position in the Y-axis direction where it reaches its maximum value Wmax toward one end, and then gradually decreases from this position toward the other end in the Y-axis direction. This creates a node region at one end of the vibrating portion 120 where the contour vibration exhibits minimal displacement, and also where the strain caused by the contour vibration is minimal. Therefore, in addition to suppressing energy leakage caused by displacement, energy leakage caused by strain can also be suppressed, further improving vibration containment.

[0076] If used Figure 3 As described above, the Y-axis position where the X-axis width W reaches its maximum value Wmax is offset from the center line CL2 passing through the Y-axis center of the vibration unit 120. This makes it easy to form a region with small displacement and strain at the Y-axis end of the vibration unit 120.

[0077] The position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax is from the center line CL2 in the Y-axis direction of the vibration unit 120 toward one end side in the Y-axis direction of the vibration unit 120 ( Figure 3 Thus, the vibration part 120 can be offset at one end in the Y-axis direction ( Figure 3 The middle and lower ends) easily form areas with small displacement and small strain.

[0078] In this embodiment, a piezoelectric resonator in which the vibration portion 120 includes the piezoelectric thin film F3 is used as the resonator 10, but the present invention is not limited to this. For example, the resonator 10 may be a ceramic resonator in which the vibration portion 120 includes a ceramic film, or an electrostatic resonator (sometimes also referred to as an electrostatic resonator) in which the vibration portion 120 includes an electrostatic film.

[0079] In addition, in this embodiment, the resonator 10 is shown as including the supporting arm 111 having a rectangular shape in a plan view, but the present invention is not limited thereto and other configurations are also possible as long as the vibrating portion 120 and the holding portion 140 are connected.

[0080] Modifications

[0081] Figure 10 Yes Figure 3 FIG. 1 is a top view of a modified example of the resonator 10 shown. Figure 10 The stacked structure of the resonator 10' is shown in FIG. Figure 4 and Figure 5 The cross-sectional structures of the resonators 10 shown are the same, and therefore illustration and description of the structures are omitted.

[0082] Figure 10 The resonator 10' shown has a support unit 110 instead of Figure 3 The support arm 111 is shown. The support unit 110 corresponds to another example of the "support portion" of the present invention.

[0083] The support unit 110 is provided inside the holding portion 140, and one end portion ( Figure 10The support unit 110 connects one end of the vibrating portion 120 to the frame 140b of the holding portion 140. Although not shown, the metal layer E1 is formed on the surface of the support unit 110 from the vibrating portion 120 to the frame 140b.

[0084] The support unit 110 of this variation includes a node generating portion 130. Node generating portion 130 is connected to one end of the vibrating portion 120 via an arm 111a and to a frame 140b of the holding portion 140 via an arm 111b. Node generating portion 130 also has a side 131 that faces one end of the vibrating portion 120 and is connected to arm 111a at this side 131.

[0085] The node generating portion 130 has a shape in which the width along the X-axis direction becomes narrower as it moves from the arm 111a toward the arm 111b. In addition, the node generating portion 130 has a shape that is line-symmetrical with respect to the perpendicular bisector of the side 131. The node generating portion 130 has a portion in which the width along the Y-axis direction becomes the largest on the side closer to the arm 111a than the center in the Y-axis direction. Figure 10 In the illustrated variation, the width of node generating portion 130 along the X-axis is greatest at edge 131, gradually narrowing from arm 111a toward arm 111b, and reaching its narrowest position at the junction of the vertex of node generating portion 130 and arm 111b. Furthermore, the width of node generating portion 130 along the Y-axis does not need to be continuously narrowed; for example, it may be gradually narrowed overall, even if it narrows in stages or has a partially expanded portion. Furthermore, the periphery of node generating portion 130 is not limited to a uniformly smooth shape and may also have concave and convex portions.

[0086] In this variation, the node generating portion 130 is formed, for example, in the shape of a semicircle with a radius of about 30 μm and a side 131 as a diameter. In this case, the center of the circle forming the arc of the node generating portion 130 is located at the center of the side 131. In addition, the center of the circle forming the arc of the node generating portion 130 may also be located at the center of the arm 111b. In addition, the side 131 is not limited to a straight line shape, but may also be an arc shape. In this case, the arm 111a is connected to the vertex of the side 131. In this case, the center of the circle forming the arc of the side 131 may be located on the arm 111a side or on the arm 111b side. The length of the side 131 is preferably greater than the width of the arm 111a along the X-axis direction and smaller than the short side of the vibration portion 120.

[0087] The node generating portion 130 of the support unit 110 in this modified example is constructed such that its width along the X-axis direction gradually narrows as it moves from arm 111a toward arm 111b. Therefore, even when the propagation state of the vibration propagating from the vibrating portion 120 changes, a portion with small displacement is formed in the node generating portion 130 adjacent to a portion with large displacement caused by the vibration. Thus, the node generating portion 130 can adjust the displacement portion in response to the vibration leaking from the vibrating portion 120, thereby forming a vibration node on the node generating portion 130. The node generating portion 130 is connected to arm 111a at this formed node, thereby suppressing the propagation of vibration from the vibrating portion 120 to the retaining portion 140. As a result, the anchoring loss of the resonator 10 can be reduced, and the Q value can be improved.

[0088] [Second embodiment]

[0089] Next, refer to Figures 11 to 15 The resonant device and resonator according to the second embodiment of the present invention are described. Structures identical or similar to those in the first embodiment are denoted by identical or similar reference numerals. Differences from the first embodiment are described below. Similar effects achieved by identical structures are not listed sequentially.

[0090] First, refer to Figure 11 A schematic structure of a resonator according to a second embodiment of the present invention will be described. Figure 11 1 is a plan view schematically showing the structure of the resonator 10A in the second embodiment. Figure 11 is the same as in the first embodiment Figure 3 Corresponding top view.

[0091] like Figure 11 As shown, the resonator 10A of the second embodiment is different from the resonator 10 of the first embodiment in that it includes a vibration portion 120A having an XY plane contour different from that of the vibration portion 120 described above.

[0092] When viewed from above, the vibration unit 120A is formed by combining two triangles, more specifically, two isosceles triangles, with the base of one triangle joined to the base of the other triangle. Furthermore, the vibration unit 120A, like the vibration unit 120 of the first embodiment, may be formed from two components or a single component.

[0093] The length L of one triangular portion of the vibrating part 120A along the Y axis has a maximum value L1max at a position passing through the vertex of the triangle. The length L of the other triangular portion of the vibrating part 120A along the Y axis has a maximum value L2max at a position passing through the vertex of the triangle.

[0094] The width W of the vibration part 120A along the X-axis direction has a maximum value Wmax at a position passing through the boundary between one triangle and the other triangle. The width W of the vibration part 120A in the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward one end in the Y-axis direction ( Figure 11 The width W in the X-axis direction gradually decreases, and the width W in the Y-axis direction gradually decreases from the position in the Y-axis direction where the width W in the X-axis direction becomes the maximum value Wmax toward the other end in the Y-axis direction ( Figure 11 Thus, a node region of contour vibration with small displacement can be formed at one end of the vibration portion 120A, and a region with small strain caused by contour vibration can be formed.

[0095] like Figure 11 As shown in FIG. 1 , the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax is offset from the center line CL2 passing through the center of the vibration part 120A in the Y-axis direction. More specifically, this position is offset from the center line CL2 in the Y-axis direction of the vibration part 120A toward one end side in the Y-axis direction of the vibration part 120A ( Figure 11 Offset on the negative Y-axis.

[0096] In this embodiment, the maximum value L1max of the length L in the Y-axis direction of one triangle is set to 0.8 times the maximum value Wmax of the width W in the X-axis direction. Furthermore, the maximum value L2max of the length L in the Y-axis direction of the other triangle is set to 0.25 times the maximum value Wmax of the width W in the X-axis direction. The maximum value Wmax of the width W in the X-axis direction is, for example, approximately 160 μm. Thus, in the vibrating portion 120A, the length L in the Y-axis direction is greater than the width W in the X-axis direction, resulting in a long, strip-like shape in the Y-axis direction.

[0097] In addition, the support arm 111 is connected to one end portion of the vibration portion 120A ( Figure 11 lower middle end).

[0098] Next, refer to Figure 12 and Figure 13 The displacement caused by the vibration of the vibrating part is described. Figure 12 and Figure 13 The stacked structure of the vibration part 120A and the above-mentioned Figure 6 and Figure 7 The stacked structure of the vibration part 120 is the same. Figure 12 and Figure 13 It is schematically represented Figure 11 FIG. 1 is a top view of the vibration mode of the vibration portion 120A shown in FIG. Figure 12 and Figure 13In the illustrated vibration portion 120A, a light-colored area indicates a large displacement, and a dark-colored area indicates a small displacement.

[0099] like Figure 12 As shown in FIG. 1 , in some cases, the vibration portion 120A is in a contracted state in the XY plane. Specifically, in Figure 12 The three parts indicated by black arrows in FIG. 1 are displaced significantly in the direction of contraction toward the central portion of the vibration part 120A. At this time, the central portion of the vibration part 120A and one end portion of the vibration part 120A connected to the support arm 111 ( Figure 12 The displacement of the middle and lower ends becomes smaller.

[0100] In addition, in other cases, such as Figure 13 As shown in FIG. 1 , the vibration portion 120A is in an expanded state in the XY plane. Specifically, Figure 13 The three parts indicated by black arrows in FIG. 1 are greatly displaced in the direction extending from the center of the vibration part 120A. At this time, the center of the vibration part 120A and one end of the vibration part 120A connected to the support arm 111 ( Figure 13 The displacement of the middle and lower ends also becomes smaller.

[0101] Next, refer to Figure 14 and Figure 15 , the displacement distribution and strain distribution based on the vibration of the vibration part are described. Figure 14 and Figure 15 The stacked structure of the vibration part 120A and the above-mentioned Figure 6 and Figure 7 The stacked structure of the vibration part 120 is the same. Figure 14 It is a schematic representation based on Figure 11 The diagram shows a perspective view of the displacement distribution of the vibration portion 120A. Figure 15 It is a schematic representation based on Figure 11 The three-dimensional diagram of the strain distribution of the vibration part 120A shown in FIG. Figure 14 In the vibration part 120A shown in FIG. 1 , the light-colored area indicates a large displacement, and the dark-colored area indicates a small displacement. Figure 15 In the illustrated vibration portion 120A, a light-colored area indicates a large strain, and a dark-colored area indicates a small strain.

[0102] like Figure 14 As shown, in the vibration part 120A, Figure 12 and Figure 13 The displacement of the three regions indicated by black arrows in the figure becomes larger. On the other hand, the displacement of the central portion of the vibration portion 120A and one end portion of the vibration portion 120A provided with the support arm 111 becomes smaller.

[0103] like Figure 15As shown in FIG. 1 , the strain in the center of the vibration part 120A becomes larger. Figure 12 and Figure 13 The strain in the three regions indicated by black arrows and the end portion of the vibration portion 120A provided with the support arm 111 becomes smaller. In other words, the end portion of the vibration portion 120A becomes a region with small displacement and small strain. Figure 11 As shown, when viewing the top surface of the vibrating portion 120A from above, the width W in the X-axis direction gradually decreases from a position in the Y-axis direction where it reaches its maximum value Wmax toward one end, and then gradually decreases from this position toward the other end in the Y-axis direction. This allows the formation of a node region at one end of the vibrating portion 120A where the displacement of the contour vibration is small, and where the strain caused by the contour vibration is small. Therefore, the resonator 10A of this embodiment and the resonator device including this resonator 10A can achieve the same effects as the resonator 10 and resonator device 1 of the first embodiment.

[0104] [Third embodiment]

[0105] Next, refer to Figure 16 and Figure 17 The resonant device and resonator according to the third embodiment of the present invention will be described. Components identical or similar to those in the first and second embodiments are denoted by identical or similar reference numerals. Differences from the first and second embodiments will be described below. The same functions and effects achieved by identical components will not be listed sequentially.

[0106] Reference Figure 16 and Figure 17 A schematic structure of a resonator according to a third embodiment of the present invention will be described. Figure 16 It is a plan view schematically showing the structure of a resonator 10B in the first example of the third embodiment. Figure 17 : is a plan view schematically showing the structure of the resonator 10C in the second example of the third embodiment. Figure 16 and Figure 17 is the same as in the first embodiment Figure 3 Corresponding top view.

[0107] like Figure 16 and Figure 17 As shown, the resonators 10B and 10C of the third embodiment differ from the resonator 10 of the first embodiment and the resonator 10A of the second embodiment in that they include vibrating portions 120B and 120C having contours in the XY plane different from those of the vibrating portions 120 and 120A described above.

[0108] When viewed from above, the vibration parts 120B and 120C have a shape formed by combining a semi-ellipse with a depression or protrusion in one portion and a semi-ellipse, and have a shape formed by joining the minor axis of the semi-ellipse with the major axis of the semi-ellipse. Furthermore, like the vibration part 120 of the first embodiment, the vibration parts 120B and 120C may be formed from two components or a single component.

[0109] The length L of the semi-elliptical portion of each of the vibrating parts 120B and 120C along the Y-axis direction has a maximum value, L1max, at a position passing through the major axis of the ellipse. The length L of the semi-elliptical portion of each of the vibrating parts 120B and 120C along the Y-axis direction has a maximum value, L2max, at a position passing through the minor axis of the ellipse.

[0110] The width W of the vibrating parts 120B and 120C along the X-axis direction has a maximum value Wmax at a position in the Y-axis direction passing through the boundary between the semi-ellipses. The width W of the vibrating parts 120B and 120C along the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward one end in the Y-axis direction ( Figure 16 and Figure 17 The width W in the X-axis direction becomes smaller and smaller, and moves from the Y-axis direction position where the width W in the X-axis direction becomes the maximum value Wmax toward the other end in the Y-axis direction ( Figure 16 and Figure 17 The upper and middle end) becomes smaller.

[0111] More specifically, the width W of the vibration parts 120B and 120C in the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward one end in the Y-axis direction ( Figure 16 and Figure 17 On the other hand, the width W of the vibration parts 120B and 120C in the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward the other end in the Y-axis direction ( Figure 16 and Figure 17 The upper and middle end portion) decreases sharply in the middle, or increases within a range smaller than the maximum value Wmax.

[0112] Thus, the width W of the vibration parts 120B and 120C in the X-axis direction increases from the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax toward the other end in the Y-axis direction ( Figure 16 and Figure 17In the case where a portion of the width W in the X-axis direction decreases or increases sharply, it is sufficient as long as it is smaller than the maximum value Wmax. In addition, although not shown in the figure, the width W in the X-axis direction of the vibration parts 120B and 120C is greater than the maximum value Wmax even when the width W in the X-axis direction reaches the maximum value Wmax from the position in the Y-axis direction toward one end in the Y-axis direction ( Figure 16 and Figure 17 Even if the value Wmax is significantly less than the maximum value Wmax (e.g., the middle and lower ends), and similarly, a portion thereof decreases or increases sharply, it only needs to be less than the maximum value Wmax. In these cases, as with the vibrating portion 120 of the first embodiment, a node region of contour vibration with small displacement can be formed at one end of the vibrating portions 120B and 120C, and a region with small strain caused by contour vibration can be formed. Therefore, the resonators 10B and 10C of this embodiment, and the resonant devices including these resonators 10B and 10C, can achieve the same operational effects as the resonator 10 and resonant device 1 of the first embodiment.

[0113] like Figure 16 and Figure 17 As shown in FIG. 1 , the position in the Y-axis direction where the width W in the X-axis direction reaches the maximum value Wmax is offset from the center line CL2 passing through the center of the vibrating parts 120B and 120C in the Y-axis direction. More specifically, this position is offset from the center line CL2 in the Y-axis direction of the vibrating parts 120B and 120C toward one end portion in the Y-axis direction of the vibrating parts 120B and 120C ( FIG. 1 ). Figure 16 and Figure 17 Offset on the negative Y-axis.

[0114] The above describes exemplary embodiments of the present invention. In a resonator according to one embodiment of the present invention, the width of the vibrating portion in the X-axis direction decreases from a maximum Y-axis position toward one end, and further decreases from this position toward the other end in the Y-axis direction, when viewed from above on one principal surface of the substrate. This creates a node region at one end of the vibrating portion where the contour vibration exhibits minimal displacement and a region where the strain caused by the contour vibration is minimal. Therefore, in addition to suppressing energy leakage caused by displacement, energy leakage caused by strain can also be suppressed, further improving vibration containment.

[0115] In the resonator, the Y-axis position where the X-axis width reaches its maximum is offset from a centerline passing through the Y-axis center of the vibrating portion. This makes it easy to form regions with small displacement and strain at the Y-axis ends of the vibrating portion.

[0116] Furthermore, in the resonator, the position in the Y-axis direction where the width in the X-axis direction reaches its maximum is offset from the Y-axis centerline of the vibrating portion toward one end of the vibrating portion in the Y-axis direction. This facilitates the formation of a region with low displacement and strain at the one end of the vibrating portion in the Y-axis direction.

[0117] Furthermore, in the resonator described above, the length in the Y-axis direction is greater than the width in the X-axis direction. This makes it possible to easily realize a resonator with further improved vibration confinement.

[0118] In the resonator described above, the support arm or the support unit is connected to the center portion of one end portion of the vibrating portion in the X-axis direction. This makes it possible to easily realize a resonator with further improved vibration containment.

[0119] In the resonator described above, the vibration portion includes a metal layer and a piezoelectric thin film disposed between the Si substrate and the metal layer. This makes it possible to easily realize a piezoelectric resonator with further improved vibration confinement.

[0120] In the above resonator, the vibration portion further includes a metal layer disposed between the Si substrate and the piezoelectric thin film. This makes it possible to more easily realize a piezoelectric resonator with further improved vibration confinement.

[0121] Furthermore, the resonator further includes a protective film formed so as to cover the metal layer, thereby preventing, for example, oxidation of the metal layer serving as the upper electrode for piezoelectric vibration.

[0122] In the resonator, the substrate is made of silicon (Si), thereby increasing the mechanical strength of the vibrating portion.

[0123] In the resonator, the substrate is made of degenerate silicon (Si), thereby improving the frequency-temperature characteristics of the vibrating portion.

[0124] Furthermore, in the resonator described above, the vibrating portion further includes a modified layer formed on the other principal surface of the Si substrate. This reduces temperature-dependent changes in the resonant frequency of the stacked structure comprising the Si substrate, the metal layer, the piezoelectric thin film, and the modified layer, thereby improving the temperature characteristics of the vibrating portion.

[0125] A resonance device according to one embodiment of the present invention includes the above-described resonator, an upper cover, and a lower cover. This makes it possible to easily realize a resonance device with further improved vibration containment.

[0126] In addition, the embodiments described above are intended to make the present invention easy to understand and are not intended to limit the present invention. The present invention can be changed / improved without departing from its main purpose, and the present invention also includes its equivalents. That is, those skilled in the art make appropriate design changes to the embodiments and / or modifications, as long as they have the characteristics of the present invention, they are included in the scope of the present invention. For example, the various elements and their configurations, materials, conditions, shapes, sizes, etc. possessed by the embodiments and / or modifications are not limited to those illustrated and can be appropriately changed. In addition, the embodiments and modifications are examples, and of course, local replacement or combination of the structures shown in different embodiments and / or modifications can be performed, and as long as they include the characteristics of the present invention, they are included in the scope of the present invention.

[0127] Description of Reference Numerals

[0128] 1…resonant device; 10, 10', 10A, 10B, 10C…resonator; 20…lower cover; 21…recess; 22…bottom plate; 23…side wall; 30…upper cover; 31…recess; 33…side wall; 110…support unit; 111…support arm; 111a, 111b…arm; 120, 120A, 120B, 120C…vibrating portion; 125…protective film; 130…node generating portion; 131…edge; 140…holding portion; 140a, 140b, 140c, 140d…frame; CL1…center line; CL2…center line; E1…metal layer; E2…metal layer; F1…correction layer; F2…Si substrate; F3…piezoelectric film; L…length; L1max…maximum value; L2max…maximum value; W…width; Wmax…maximum value.

Claims

1. A resonator, wherein: have: The vibration portion includes a substrate having a first main surface having a width in a first direction and a length in a second direction, and vibrates mainly by contour vibration; a holding portion formed to surround at least a portion of the vibration portion; as well as a supporting portion extending along the second direction and connecting the holding portion and one end portion of the vibrating portion in the second direction; When the first main surface is viewed from above, the width of the vibration portion in the first direction is configured to change from one end portion toward the other end portion in the second direction across the entire region of the vibration portion, and the width in the first direction decreases from a position where the width in the first direction in the second direction becomes the largest toward the one end portion, and the width in the first direction decreases from the position toward the other end portion in the second direction.

2. The resonator according to claim 1, wherein When the first main surface is viewed from above, the width of the vibration portion in the first direction gradually decreases across the entire region of the vibration portion, from the position where the width in the first direction in the second direction is the largest toward the one end, and from the position toward the other end in the second direction.

3. The resonator according to claim 1 or 2, wherein: The position is offset from the center of the vibration portion in the second direction.

4. The resonator according to claim 3, wherein The position is offset from the center of the vibrating portion in the second direction toward the one end portion.

5. The resonator according to claim 1 or 2, wherein: The length in the second direction is greater than the width in the first direction.

6. The resonator according to claim 1 or 2, wherein: The support portion is connected to a central portion of the one end portion in the first direction.

7. The resonator according to claim 1 or 2, wherein: The vibration portion includes a first electrode and a piezoelectric layer disposed between the substrate and the first electrode.

8. The resonator according to claim 7, wherein The vibration portion further includes a second electrode disposed between the substrate and the piezoelectric layer.

9. The resonator according to claim 7, wherein The vibration part further includes a protection layer formed to cover the first electrode.

10. The resonator according to claim 1 or 2, wherein: The substrate is made of silicon.

11. The resonator according to claim 1 or 2, wherein: The substrate is made of degenerate silicon.

12. The resonator according to claim 1 or 2, wherein: The vibration portion further includes a correction layer formed on the second main surface of the substrate.

13. A resonant device, wherein: have: The resonator according to any one of claims 1 to 12; and Cover body.

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