Resonator and electronic device

Abstract

This resonator comprises a spring part and a first support part. The spring part is extendable / compressible along a first axis and is configured in a two-dimensional bellows shape. The first support part has a first connection part connected to the spring part and supports the spring part. The first support part is capable of elastic deformation such that the first connection part is displaced along a second axis which is orthogonal to the first axis.

Description

Resonator and Electronic Device

[0001] The present disclosure relates to a resonator and an electronic device.

[0002] A resonator having a spring portion configured in a two-dimensional bellows shape is known (Patent Document 1 below).

[0003] Japanese National Publication of International Patent Application No. 2022-529131

[0004] A resonator according to an aspect of the present disclosure includes a spring portion and a first support portion. The spring portion is expandable and contractible along a first axis, and is configured in a two-dimensional bellows shape. The first support portion has a first connection portion connected to the spring portion, and supports the spring portion. The first support portion is elastically deformable such that the first connection portion is displaced along a second axis orthogonal to the first axis.

[0005] An electronic device according to an aspect of the present disclosure includes the resonator described above, and a circuit that applies a voltage to the resonator.

[0006] A plan view of the resonator according to the embodiment. An enlarged view of region II in FIG. 1. A cross-sectional view of the resonator in FIG. 1.

[0007] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, dimensional ratios and the like on the drawings do not necessarily match those in reality. In addition, dimensional ratios and the like may not match between different drawings. Certain shapes and / or dimensions and the like may be exaggerated, and details may be omitted. However, the above does not preclude that actual shapes and / or dimensions may be as shown in the drawings, or that features of shapes and / or dimensions may be extracted from the drawings.

[0008] FIG. 1 is a plan view of a resonator 1 according to an embodiment. For convenience, an orthogonal coordinate system D1D2D3 is attached to FIG. 1 and other drawings. The resonator 1 may be used in any orientation. However, for convenience, unless otherwise specified, expressions may be used on the premise that the +D3 side is the upper side.

[0009] In describing embodiments, when we say, for example, that the shape and / or dimensions are "the same" or "symmetrical," it is natural that errors (tolerances) due to processing accuracy, etc., may exist. In piezoelectric materials (especially single crystals), shapes that should be "the same" or "symmetrical" may differ relatively significantly due to anisotropy caused by etching. These differences may also be included in the tolerance. The term "shape" may refer to the shape alone, or to a combination of shape and dimensions. Either interpretation is acceptable as long as it does not create any contradictions.

[0010] (Overall configuration of the resonator) The resonator 1 is, for example, a roughly plate-shaped electronic component with the D3 direction as the thickness direction. Its dimensions are arbitrary. For example, the length in the D1 direction and the length in the D2 direction of the resonator 1 (or the resonator body 1a described later) may be 100 μm or more and 1000 μm or less. The thickness of the resonator 1 or the resonator body 1a may be, for example, 3 μm or more and 100 μm or less.

[0011] The resonator 1 has a spring portion 3 configured in a two-dimensional bellows shape. The spring portion 3 is expandable and contractible in the D1 direction. The spring portion 3 has a piezoelectric element in the part that deforms as it expands and contracts. When a voltage is applied to the piezoelectric element, the spring portion 3 vibrates as it expands and contracts, and the electrical signal generated by this vibration is extracted. The resonator 1 can be used for any purpose, for example, as an oscillator, filter, or sensor.

[0012] In the resonator 1, for example, the principal vibration related to the expansion and contraction of the spring portion 3 may be used. The principal vibration is, in other words, the vibration of the fundamental mode. Theoretically, the wavelength of the fundamental mode vibration is four times the length of the first spring portion 5A or the second spring portion 5B, which is supported in a cantilevered manner and will be described later. The resonant frequency of the fundamental mode is often the lowest among the resonant frequencies related to expansion and contraction. Also, the displacement of the free end (or, from another perspective, the weight portion 9, which will be described later) in the vibration of the fundamental mode is the largest among the vibrations of the multiple modes related to expansion and contraction. The specific value of the resonant frequency of the principal vibration is arbitrary and may be, for example, 10 kHz or more and 300 kHz or less.

[0013] The resonator 1 may have, in addition to the spring portion 3, the following components: • Support portion 7 (first support portion 7A and second support portion 7B): Supports the spring portion 3. • Weight portion 9: Supported by the spring portion 3 and displaced as the spring portion 3 expands and contracts. • Support base portion 11: Supports the support portion 7. The combination of the spring portion 3, support portion 7, and weight portion 9 (in other words, the portion of the resonator 1 excluding the support base portion 11) is sometimes referred to as the resonator body 1a (indicated in Figure 3). Contrary to this explanation, the resonator body 1a alone may be considered as the resonator.

[0014] The support portion 7 has connecting portions 21 (first connecting portion 21A and second connecting portion 21B) that are connected to the spring portion 3. The support portion 7 is configured to be elastically deformable so that the connecting portions 21 are displaced along the D2 direction.

[0015] More specifically, in the illustrated example, each support section 7 is configured in a roughly T-shape. That is, each support section 7 has an inner beam 17 (first inner beam 17A or second inner beam 17B) extending along the D2 direction and an outer beam 19 (first outer beam 19A or second outer beam 19B) along the D1 direction. The inner beam 17 has a connecting section 21. The connecting section 21 is connected to the central portion 3a of the spring section 3. The outer beam 19 is connected to the inner beam 17 on the opposite side from the connecting section 21. When the outer beam 19 bends in the D2 direction, the connecting section 21 (central portion 3a) is displaced in the D2 direction. The outer beam 19 has a shape that is symmetrical with respect to an axis of symmetry (not shown) parallel to the D2 direction. If wiring is provided on the outer beam 19, the wiring may also have a similarly symmetrical shape.

[0016] Here, as an unwanted vibration, the spring portion 3 may form a fan shape, and vibrations may occur such that the center side of the fan alternates between the -D2 side and the +D2 side (from another perspective, vibrations that cause bending deformation of the spring portion 3). Generally, bending stiffness is lower than axial stiffness, and consequently, the resonant frequency of the unwanted vibration is lower than the resonant frequency of the main vibration. The fact that the central portion 3a is movable in the D2 direction corresponds to a decrease in the bending stiffness of the spring portion 3. As a result, the discrepancy between the resonant frequency of the unwanted vibration and the resonant frequency of the main vibration becomes larger. Consequently, the influence of the unwanted vibration on the main vibration can be reduced.

[0017] The resonator body 1a (or resonator 1; the same applies hereinafter in this paragraph) has a shape that is symmetrical with respect to an axis of symmetry (not shown) parallel to the D2 direction, for example. The resonator body 1a also has a shape that is symmetrical with respect to an axis of symmetry (not shown) parallel to the D1 direction, for example. The resonator body 1a also has a shape that is point-symmetrical with respect to a point of symmetry (not shown). Each of the above axes of symmetry passes through, for example, the central portion 3a of the spring portion 3, and more specifically, through the center of gravity G of the resonator body 1a. The above point of symmetry is located, for example, the central portion 3a, and more specifically, at the center of gravity G of the resonator body 1a. The center of gravity G may be considered as the center of gravity of the vibrating part (combination of spring portion 3 and weight portion 9) that vibrates in conjunction with the expansion and contraction of the spring portion 3.

[0018] (Spring section) The spring section 3 has, for example, a first spring section 5A and a second spring section 5B connected in series with each other in the direction of expansion and contraction. A central section 3a is interposed between the first spring section 5A and the second spring section 5B. The center of gravity G is located, for example, at the center of the central section 3a. Ideally, the first spring section 5A and the second spring section 5B expand and contract together at the same time. Also, ideally, the center of gravity G does not displace.

[0019] The first spring section 5A and the second spring section 5B are supported by the central section 3a, and the central section 3a is supported by the support section 7. Consequently, the ends of the first spring section 5A and the second spring section 5B that are connected to the central section 3a are fixed ends. The ends on the opposite side of the central section 3a (towards the weight section 9) are free ends. The fixed ends are restricted from intentional displacement, while the free ends are permitted to be intentionally displaced.

[0020] The first spring section 5A has a plurality of beams 13 (six in the illustrated example) that extend in parallel to each other in the D2 direction from the central side in the D2 direction to the +D2 side (the portion shown as region II). The plurality of beams 13 are arranged in the D1 direction, with their +D2 side ends and -D2 side ends alternately connected by bases 15. That is, the plurality of beams 13 and the plurality of bases 15 as a whole extend in a zigzag pattern. The number of beams 13 and bases 15 is arbitrary. For example, the number of beams 13 may be two or more, or six or more.

[0021] The portion of the first spring 5A on the +D2 side has been described, but the same applies to the portion of the first spring 5A on the -D2 side. Furthermore, the base portion 15 located on the central side in the D2 direction of the first spring 5A connects the multiple beams 13 on the +D2 side and the multiple beams 13 on the -D2 side. In other words, the first spring 5A as a whole, including the portion on the +D2 side and the portion on the -D2 side, has a shape in which the two-dimensional bellows-like inner (central side in the D2 direction) bends are connected every other.

[0022] The first spring section 5A has been described, and the same applies to the second spring section 5B. In the above explanation, the beam 13 located on the +D2 side and the beam 13 located on the -D2 side of the spring section 3 were treated as separate entities. However, two beams 13 connected in series may be treated as a single beam.

[0023] The specific shapes and dimensions of the beams 13, bases 15, and central portion 3a are arbitrary. For example, multiple beams 13 basically have the same shape and dimensions as each other (except for the beams 13 connected to the central portion 3a). Multiple bases 15 on the central side of the spring portion 3 in the D2 direction have the same shape and dimensions as each other. Multiple bases 15 on both sides of the spring portion 3 in the D2 direction have the same shape as each other. The beams 13, bases 15, and central portion 3a are each roughly rectangular parallelepipeds.

[0024] In the illustrated example, the length of the central portion 3a in the D2 direction is longer than the length of the central base portion 15 of the spring portion 3 in the D2 direction. As a result, among the multiple beams 13, the beam 13 connected to the central portion 3a is shorter than the other beams 13. However, the length of the central portion 3a in the D2 direction may be the same as the length of the central base portion 15 in the D2 direction.

[0025] (Support section) As previously described, the support section 7 has an inner beam 17 and an outer beam 19. The inner beam 17 extends from the connection section 21 as previously described along the D2 direction. The outer beam 19 has a relay section 23 (first relay section 23A and second relay section 23B) connected to the inner beam 17 on the opposite side of the connection section 21. The outer beam 19 is elastically deformable so that the relay section 23 is displaced along the D2 direction. As a result, as previously described, the connection section 21 is displaceable in the D2 direction.

[0026] More specifically, in the illustrated example, the outer beam 19 extends along the D1 direction and is supported at both ends by the support base 11. It is also capable of bending and deforming in the D2 direction. Although not specifically shown, the outer beam 19 may not be a straight beam, but may have an appropriate number of bends at appropriate angles, and / or portions that extend in a curved manner. In the illustrated example or other examples, the outer beam 19 may have a shape that is symmetrical with respect to an axis of symmetry (not shown) parallel to the D2 direction, passing through the intermediate portion 23.

[0027] The specific shapes and dimensions of the inner beam 17 and outer beam 19 are arbitrary. For example, the inner beam 17 and outer beam 19 may each be rectangular parallelepipeds. The intermediate section 23 may be located in the center along the length of the outer beam 19. The widths of the inner beam 17 and outer beam 19 may be smaller, the same as, or larger than the width of the beam 13. The relative sizes of the widths of the inner beam 17 and outer beam 19 are also arbitrary.

[0028] The inner edge of the outer beam 19 on the side of the spring portion 3 has a length greater than or equal to the length of the vibrating portion in the D1 direction in order to allow for displacement of the vibrating portion (spring portion 3 and weight portion 9). On the other hand, the length of the outer edge of the outer beam 19 on the side opposite to the spring portion 3 (the outer edge) (or, from another perspective, the length of the outer beam 19) is arbitrary. For example, the length of the outer edge may be the same as the length of the inner edge.

[0029] The size of the clearance C1 between the inner edge of the outer beam 19 and the vibrating part (spring part 3 and weight part 9) is arbitrary. For example, the size of the clearance C1 may be set so that the weight part 9 does not collide with the outer beam 19 when unwanted vibrations of a predetermined magnitude occur. Also, for example, the clearance C1 may be 0.5 times or more, 1.0 times or more, or 1.5 times or more than the clearance C2 between the spring part 3 and the weight part 9. The clearance between the outer edge of the outer beam 19 and the support base 11 is also arbitrary.

[0030] Although not specifically shown in the figures, only one of the first support portion 7A and the second support portion 7B may be provided.

[0031] (Weight portion and support base) The weight portion 9 is provided, for example, one on each side of the spring portion 3 in the D1 direction (two in total). The weight portion 9 is connected, for example, to the central position of the spring portion 3 in the D2 direction. The shape and dimensions of the weight portion 9 are arbitrary. In the illustrated example, the weight portion 9 is a rectangular parallelepiped with the same length as the length of the spring portion 3 in the D2 direction. The length of the weight portion 9 in the D1 direction may be smaller than the width of the beam 13 (length in the D1 direction), equal to it, or larger than it.

[0032] The shape and dimensions of the support base 11 are arbitrary. In the illustrated example, the support base 11 is configured as a frame surrounding the resonator body 1a. The cross-sectional shape is, for example, rectangular.

[0033] (Example of electrodes) Figure 2 shows an example of electrodes on the resonator 1. This figure is an enlarged view of region II in Figure 1.

[0034] The resonator 1 has a piezoelectric layer, as will be described later with reference to Figure 3. The piezoelectric layer extends, for example, across at least a number of beams 13. Alternatively, for example, the piezoelectric layer extends across the entire resonator body 1a or the entire resonator 1. A conductor layer is superimposed on the upper surface of the piezoelectric layer, either directly or indirectly via a relatively thin insulating film. In Figure 2, hatching is applied to the surface of the conductor layer for convenience.

[0035] The resonator 1 has two types of electrodes 31 (a first electrode 31A and a second electrode 31B) with different potentials. Each electrode 31 extends along the edge of the upper surface of each beam 13. The first electrode 31A and the second electrode 31B extend along the opposite edges of each beam 13. In each beam 13, the position of the first electrode 31A and the second electrode 31B on the +D1 side and the -D1 side are reversed between the +D2 side and the -D2 side of each beam 13, and also reversed between adjacent beams 13. In the center of each beam 13, the first electrode 31A and the second electrode 31B intersect in three dimensions via an insulator (not shown).

[0036] The piezoelectric layer is, for example, polarized in the D1 direction. Therefore, when a voltage of one polarity is applied to the first electrode 31A and the second electrode 31B, one beam 13 expands and the other beam 13 contracts at the +D2 side portion of two beams 13 connected to each other at their +D2 sides. As a result, the +D2 side portions of the two beams 13 bend to one side in the D1 direction. Similarly, the -D2 side portions of two beams 13 connected to each other at their -D2 sides bend to the same one side in the D1 direction. If the polarity is reversed, each portion bends to the opposite side (the other side in the D1 direction). This causes the +D2 side portion of the first spring portion 5A to expand and contract in the D1 direction.

[0037] Although not specifically shown in the figures, two types of electrodes 31 may be arranged in the -D2 side portion of the first spring portion 5A, the +D2 side portion of the second spring portion 5B, and the -D2 side portion of the second spring portion 5B, similar to the +D2 side portion of the first spring portion 5A. The direction of polarization in each portion (whether it is the +D1 side or the -D1 side) and the arrangement of the two types of electrodes 31 (the relationship between the direction from the first electrode 31A to the second electrode 31B and the positive and negative of the D1 direction) may be appropriately set so that the spring portion 3 as a whole extends or contracts in the D1 direction. For example, in the first spring portion 5A, the +D2 side portion and the -D2 side portion have the same polarization direction, and the arrangement of the two types of electrodes 31 is symmetrical with respect to an axis of symmetry parallel to the D1 direction. The first spring portion 5A and the second spring portion 5B have opposite polarization directions, and the arrangement of the two types of electrodes 31 is symmetrical with respect to an axis of symmetry parallel to the D2 direction.

[0038] The configuration of the electrodes of the resonator 1 is not limited to those described above. For example, various electrode configurations disclosed in Patent Document 1 may be applied to this embodiment.

[0039] (Example of a laminated structure) Figure 3 is a cross-sectional view showing an example of a laminated structure of the resonator 1. Details are omitted in this figure. Therefore, Figure 3 can be considered as a cross-sectional view of the resonator 1 viewed in any direction perpendicular to the D3 direction.

[0040] In the illustrated example, the resonator 1 has layers L1 to L5 stacked on top of each other. The resonator body 1a is composed of, for example, the upper layers L1 to L3. Layers L1 to L3 have, for example, the same planar shape as each other, as well as the planar shape shown in Figure 1. The resonator 1 or the support base 11 may also be considered to be composed of layers L1 to L3. Layer L4 is located only in the region of the resonator 1 that overlaps with the support base 11. Therefore, the portion of layers L1 to L3 that constitutes the resonator body 1a is separated upward from layer L5. As a result, the displacement and / or deformation of the resonator body 1a in the D1D2 plane relative to the support base 11 is facilitated.

[0041] The layer L1 is a conductive layer. The conductive layer includes, for example, an electrode 31 and a wiring extending from the electrode 31 (only a part of which is shown in FIG. 2). The material of the conductive layer is arbitrary, and may be, for example, Al, Mo, Au or polysilicon. The thickness of the layer L1 is arbitrary, and may be, for example, not less than 0.5 μm and not more than 2 μm.

[0042] The layer L2 is a piezoelectric layer. The material of the piezoelectric layer may be single crystal or polycrystal. Specific materials are also arbitrary. For example, the material of the piezoelectric layer may be AlN, ScAlN or ZnO. The thickness of the layer L2 is arbitrary, and may be, for example, not less than 0.5 μm and not more than 2 μm.

[0043] The layer L3 is a device silicon layer. The device silicon layer is made of, for example, single-crystal silicon. The device silicon layer may or may not contain a dopant. The relationship between the crystal orientation and the shape of the resonator 1 is arbitrary. The thickness of the layer L3 is arbitrary, and may be, for example, not less than 2 μm and not more than 20 μm.

[0044] Layers L4 and L5 do not directly affect the characteristics of the resonator 1, and therefore may be made of any material and have any thickness. The layer L4 is a buried oxide layer. The material is SiO ２ . The layer L5 is a handle silicon layer.

[0045] The resonator 1 may be constituted by, for example, an SOI (Silicon on Insulator) substrate. The resonator 1 may have a configuration different from the configuration illustrated in FIG. 3. For example, various laminated structures disclosed in Patent Document 1 may be applied to the present embodiment. Alternatively, the resonator 1 (or the resonator main body 1a) may be constituted only by the layers L1 and L2.

[0046] (Example of another configuration) Layer L3 may contain a dopant at a high concentration and function as a lower electrode. Alternatively, a lower electrode may be provided between layer L2 and layer L3. The lower electrode may extend over the entire layer L2 (piezoelectric layer). The piezoelectric layer may be polarized in the D3 direction. A constant potential (e.g., a reference potential) may be applied to the lower electrode. Potentials having different polarities from each other (the magnitude relative to the constant potential is opposite to each other) may be alternately applied to the first electrode 31A and the second electrode 31B.

[0047] In this case, in each of the -D2 side portion and the +D2 side portion of each beam 13, one of the -D1 side portion and the +D1 side portion may expand in the D2 direction, and the other may contract in the D2 direction. As a result, each of the -D2 side portion and the +D2 side portion may be flexurally deformed in the D1 direction. The direction of deflection in the D1 direction may be opposite between the -D2 side portion and the +D2 side portion. Adjacent beams 13 may have opposite deflection directions at their -D2 side portions, and may also have opposite deflection directions at their +D2 side portions.

[0048] (Electronic device) The resonator 1 may, for example, be housed and packaged in a box-shaped package, or may be packaged by WLP (wafer level chip size package) technology. Then, it may be mounted on a circuit board or the like to constitute the electronic device 35 (FIG. 2). The electronic device 35 may include, for example, a circuit 33 that applies a voltage to the two types of electrodes 31 (in FIG. 2, a symbol of an AC power supply is shown for convenience).

[0049] (Summary) As described above, the resonator 1 includes the spring portion 3 and the first support portion 7A. The spring portion 3 is configured in a two-dimensional bellows shape that can expand and contract along the D1 axis (an example of the first axis). The first support portion 7A includes a first connection portion 21A connected to the spring portion 3, and supports the spring portion 3. The first support portion 7A is elastically deformable such that the first connection portion 21A is displaced along a D2 axis (an example of the second axis) orthogonal to the D1 axis. Therefore, for example, the resonance frequency of unwanted vibration can be lowered, and the influence of unwanted vibration on the main vibration can be reduced.

[0050] As previously mentioned, the resonator body 1a may have a line-symmetric or point-symmetric shape. Focusing on each part, the following can also be said: The spring portion 3 may have a shape that is line-symmetric with respect to an axis of symmetry parallel to the D2 axis passing through the first connection portion 21A and / or the second connection portion 21B. The first support portion 7A and the second support portion 7B may have a positional relationship and shapes that are line-symmetric with respect to an axis of symmetry parallel to the D1 axis. The spring portion 3 may have a shape that is line-symmetric with respect to an imaginary line connecting the first connection portion 21A and the second connection portion 21B.

[0051] The technology relating to this disclosure is not limited to the embodiments described above and may be implemented in various forms. For example, the spring portion 3 may have only one of the first spring portion 5A and the second spring portion 5B.

[0052] 1... Resonator, 3... Spring section, 5A... First spring section, 5B... Second spring section, 7A... First support section, 7B... Second support section, 21A... First connection section, 21B... Second connection section.

Claims

1. A resonator comprising: a spring portion configured in a two-dimensional bellows shape that is expandable and contractible along a first axis; and a first support portion that supports the spring portion and has a first connecting portion connected to the spring portion, wherein the first support portion is elastically deformable such that the first connecting portion is displaced along a second axis perpendicular to the first axis.

2. The resonator according to claim 1, wherein the first support portion comprises a first inner beam extending from the first connection portion along the second axis, and a first outer beam having a first relay portion connected to the first inner beam on the side opposite to the first connection portion, and the first outer beam is elastically deformable such that the first relay portion is displaced along the second axis.

3. The resonator according to claim 2, wherein the first outer beam extends along the first axis, and the first relay portion is located in the center of the first outer beam.

4. The resonator according to claim 2 or 3, wherein the first outer beam has a shape that is symmetrical with respect to an axis of symmetry parallel to the second axis passing through the first relay portion.

5. The resonator according to any one of claims 1 to 4, wherein the spring portion has a shape that is symmetrical with respect to an axis of symmetry parallel to the second axis passing through the first connecting portion.

6. The resonator according to any one of claims 1 to 5, having a second connecting portion connected to the spring portion, and a second support portion supporting the spring portion, wherein the first support portion and the second support portion are located on opposite sides of the spring portion in the direction of the second axis.

7. The resonator according to claim 6, wherein the first support portion and the second support portion have a positional relationship and shapes that are symmetrical with respect to an axis of symmetry parallel to the first axis.

8. The resonator according to claim 6 or 7, wherein the first support portion comprises a first inner beam extending from the first connection portion along the second axis and a first outer beam having a first relay portion connected to the first inner beam on the side opposite to the first connection portion, and the second support portion comprises a second inner beam extending from the second connection portion along the second axis and a second outer beam having a second relay portion connected to the second inner beam on the side opposite to the second connection portion, and the first outer beam and the second outer beam extend parallel to each other along the first axis.

9. The resonator according to any one of claims 6 to 8, wherein the spring portion has a shape symmetrical with respect to an imaginary line connecting the first connecting portion and the second connecting portion.

10. The resonator according to any one of claims 1 to 9, wherein the resonant frequency of unwanted vibrations accompanied by deflection of the spring portion in the direction along the second axis is lower than the resonant frequency of the main vibration accompanied by expansion and contraction along the first axis of the spring portion.

11. A resonator according to claim 2, or any one of claims 3 to 10 that directly or indirectly references claim 2, wherein the resonator has two weight portions located on both sides of the first shaft with respect to the spring portion, and a clearance of 0.5 times or more the clearance between the spring portion and each of the weight portions is located between the weight portions and the first outer beam.

12. An electronic device having a resonator according to any one of claims 1 to 11, and a circuit connected to the resonator.

Images