WO2020153287A1 - Resonator and resonance device - Google Patents

Resonator and resonance device Download PDF

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Publication number
WO2020153287A1
WO2020153287A1 PCT/JP2020/001684 JP2020001684W WO2020153287A1 WO 2020153287 A1 WO2020153287 A1 WO 2020153287A1 JP 2020001684 W JP2020001684 W JP 2020001684W WO 2020153287 A1 WO2020153287 A1 WO 2020153287A1
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Prior art keywords
vibrating
vibration
resonator
diaphragm
holding
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PCT/JP2020/001684
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French (fr)
Japanese (ja)
Inventor
西村　俊雄
ヴィレ カーヤカリ
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株式会社村田製作所
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Publication of WO2020153287A1 publication Critical patent/WO2020153287A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/24—Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive

Definitions

  • the present invention relates to a resonator and a resonance device that vibrate in an out-of-plane bending vibration mode.
  • a resonance device using a MEMS (Micro Electro Mechanical Systems) technology has been used as a timing device, for example.
  • This resonant device is mounted on a printed circuit board incorporated in an electronic device such as a smartphone.
  • the resonator device includes a lower substrate, an upper substrate that forms a cavity between the lower substrate, and a resonator disposed in the cavity between the lower substrate and the upper substrate.
  • a base portion and a plurality of tuning fork arms each having one end connected to the base portion and extending in the Y direction are provided, and the plurality of tuning fork arms are arranged in parallel in the X direction orthogonal to the Y direction.
  • a vibrating device in which a tuning fork arm vibrates in a Z direction orthogonal to the X direction and the Y direction.
  • the resonator or the resonance device as described in Patent Document 1 is used in the range of the resonance frequency of 100 kHz or less.
  • the area of the vibrating portion is reduced, and the electrostatic capacitance of the vibrating portion is reduced.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a resonator and a resonance device capable of suppressing a decrease in electrostatic capacitance.
  • a resonator is A vibrating section including a first vibrating section and a second vibrating section, each of which vibrates in an opposite phase with the out-of-plane bending vibration as a main vibration;
  • a holding portion formed so as to surround at least a part of the vibrating portion, A holding unit that connects the vibrating unit and the holding unit, When the main surface of the vibrating portion is viewed in a plan view, the first vibrating portion is arranged on one side with respect to the holding unit, and the second vibrating portion is arranged on the other side with respect to the holding unit.
  • a resonance device is The resonator described above, A lid that forms the vibration space of the resonator, And an external electrode.
  • FIG. 1 is a perspective view schematically showing the outer appearance of a resonance device according to a first embodiment of the present invention.
  • FIG. 2 is an exploded perspective view schematically showing the structure of the resonance device shown in FIG.
  • FIG. 3 is a plan view schematically showing the structure of the resonator shown in FIG.
  • FIG. 4 is a sectional view schematically showing a configuration of a section taken along line IV-IV shown in FIG.
  • FIG. 5 is a sectional view schematically showing a configuration of a section taken along the line VV shown in FIG.
  • FIG. 6 is a perspective view schematically showing a vibration mode of the resonator shown in FIG.
  • FIG. 1 is a perspective view schematically showing the outer appearance of a resonance device according to a first embodiment of the present invention.
  • FIG. 2 is an exploded perspective view schematically showing the structure of the resonance device shown in FIG.
  • FIG. 3 is a plan view schematically showing the structure of the resonator shown in FIG.
  • FIG. 4
  • FIG. 7 is a graph showing the relationship between the frequency and the Q value depending on thermoelastic damping in the virtual vibrating portion that does not include the insulating layer shown in FIG.
  • FIG. 8 is a graph showing the relationship between the frequency and the Q value depending on thermoelastic damping in the vibration part including the insulating layer shown in FIG.
  • FIG. 9 is a graph showing the relationship between the aspect ratio and the electromechanical coupling coefficient.
  • FIG. 10 is a graph showing the relationship between the ratio of the excitation electrode length to the resonance portion length and the electromechanical coupling coefficient.
  • FIG. 10 is a perspective view schematically showing a vibration mode of a modified example of the vibrating section shown in FIG.
  • FIG. 12 is a perspective view schematically showing a vibration mode of a modification of the vibrating section shown in FIG.
  • FIG. 13 is a plan view showing a modified example of the vibrating section shown in FIG.
  • FIG. 14 is a plan view showing a modified example of the vibrating section shown in FIG.
  • FIG. 15 is a plan view showing a modified example of the vibrating section shown in FIG.
  • FIG. 16 is a plan view showing a modified example of the vibrating section shown in FIG.
  • FIG. 17 is a plan view showing a modification of the vibrating section shown in FIG.
  • FIG. 18 is a plan view showing a modification of the resonator shown in FIG.
  • FIG. 19 is a plan view showing a modification of the resonator shown in FIG.
  • FIG. 20 is a graph showing the relationship between the aspect ratio and the electromechanical coupling coefficient.
  • FIG. 21 is a graph showing the relationship between the aspect ratio and the amount of displacement of the holding unit.
  • FIG. 1 is a perspective view schematically showing the outer appearance of a resonance device 1 according to the first embodiment of the present invention.
  • FIG. 2 is an exploded perspective view schematically showing the structure of the resonance device 1 shown in FIG.
  • the resonance device 1 includes a resonator 10, and a lower lid 20 and an upper lid 30. That is, the resonance device 1 is configured by stacking the lower lid 20, the resonator 10, and the upper lid 30 in this order.
  • the lower lid 20 and the upper lid 30 of this embodiment correspond to an example of the “lid” of the present invention.
  • the side of the resonance device 1 where the upper lid 30 is provided is the top (or front), and the side where the lower lid 20 is provided is the bottom (or back).
  • the resonator 10 is a MEMS oscillator manufactured using the MEMS technology.
  • the resonance frequency of the resonator 10 is preferably in the range of 1 MHz or more and 10 MHz or less.
  • the resonator 10, the lower lid 20 and the upper lid 30 are joined together.
  • the resonator 10, the lower lid 20, and the upper lid 30 are each formed using a silicon (Si) substrate (hereinafter referred to as “Si substrate”), and the Si substrates are bonded to each other.
  • Si substrate silicon substrate
  • the upper lid 30 spreads in a flat plate shape along the XY plane, and a flat rectangular parallelepiped recess 31 is formed on the back surface thereof.
  • the recess 31 is surrounded by the side wall 33 and forms a part of a vibration space in which the resonator 10 vibrates.
  • the upper lid 30 does not have the recess 31 and may have a flat plate configuration.
  • a getter layer may be formed on the surface of the recess 31 of the upper lid 30 on the resonator 10 side.
  • the lower lid 20 has a rectangular flat plate-shaped bottom plate 22 provided along the XY plane, and a side wall 23 extending from the peripheral portion of the bottom plate 22 in the Z-axis direction, that is, in the stacking direction of the lower lid 20 and the resonator 10.
  • a recess 21 formed by the surface of the bottom plate 22 and the inner surface of the side wall 23 is formed.
  • the recess 21 forms a part of the vibration space of the resonator 10.
  • the lower lid 20 does not have the recess 21 and may have a flat plate configuration. Further, a getter layer may be formed on the surface of the recess 21 of the lower lid 20 on the resonator 10 side.
  • the vibration space of the resonator 10 is hermetically sealed by the above-described upper lid 30 and lower lid 20, and the vacuum state is maintained.
  • the vibrating space may be filled with a gas such as an inert gas.
  • FIG. 3 is a plan view schematically showing the structure of the resonator 10 shown in FIG.
  • the resonator 10 is a MEMS vibrator manufactured using the MEMS technology.
  • the resonator 10 includes a vibrating section 120, a holding section 140, and holding arms 111 and 112.
  • the holding arms 111 and 112 of this embodiment correspond to an example of the “holding unit” of the present invention.
  • the vibrating section 120 has a rectangular contour that spreads along the XY plane in the orthogonal coordinate system shown in FIG. 3 when the surface facing the upper lid 30 is viewed in plan (hereinafter, simply referred to as “plan view”). ..
  • the vibrating section 120 is provided inside the holding section 140, and spaces are formed between the vibrating section 120 and the holding section 140 at predetermined intervals.
  • the vibrating section 120 includes a first vibrating plate 135A and a second vibrating plate 135B.
  • the first diaphragm 135A and the second diaphragm 135B each have a rectangular flat plate shape.
  • the end surface of the first vibrating plate 135A on the Y axis negative direction side and the end surface of the second vibrating plate 135B on the Y axis positive direction side are connected to each other to form a connecting portion 135C.
  • the connecting portion 135C may be a member different from the first diaphragm 135A and the second diaphragm 135B.
  • first diaphragm 135A on the Y axis negative direction side and the end surface of the second diaphragm 135B on the Y axis positive direction side are connected to each other to form the connecting portion 135C.
  • the first diaphragm 135A and the second diaphragm 135B may be a single plate-shaped member that is integrally formed.
  • first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG.
  • the details of the vibration of the first diaphragm 135A and the second diaphragm 135B will be described later.
  • each of the first diaphragm 135A and the second diaphragm 135B has a main surface having a length L in the Y-axis direction and a width W in the X-axis direction.
  • the length L is about 130 ⁇ m
  • the width W is about 60 ⁇ m
  • the ratio (hereinafter, also referred to as “aspect ratio”) W/L is about 0.46.
  • the first diaphragm 135A and the second diaphragm 135B each include a metal layer E2.
  • the width of each metal layer E2 in the X-axis direction is substantially the same as the width W of the main surface, and has a length Le in the Y-axis direction.
  • the holding portion 140 is formed in a rectangular frame shape so as to surround the outside of the vibrating portion 120 along the XY plane. It should be noted that the holding section 140 may be provided so as to surround at least a part of the periphery of the vibrating section 120, and is not limited to the frame-like shape. For example, the holding unit 140 may be provided around the vibrating unit 120 so that the holding unit 140 holds the vibrating unit 120 and can be joined to the upper lid 30 and the lower lid 20.
  • the holding portion 140 includes prismatic frame bodies 140a to 140d that are integrally formed.
  • the frame 140a is provided so as to face the open end of the first diaphragm 135A and the longitudinal direction thereof is parallel to the X axis.
  • the frame 140b is provided so as to face the open end of the second diaphragm 135B and the longitudinal direction thereof is parallel to the X axis.
  • the frame 140c is provided so as to face one side end (the left end in FIG. 3) of the first vibrating plate 135A and the second vibrating plate 135B, and the longitudinal direction thereof is parallel to the Y axis. Each of them is connected to one end (the left end in FIG. 3) of 140b.
  • the frame 140d faces the other end (the right end in FIG. 3) of the first vibrating plate 135A and the second vibrating plate 135B, the longitudinal direction of which is parallel to the Y-axis, and both ends of the frame 140d, It is connected to the other end (the right end in FIG. 3) of 140b.
  • the holding arm 111 and the holding arm 112 are provided inside the holding unit 140, respectively.
  • the holding arm 111 is provided such that its longitudinal direction is parallel to the X axis.
  • the holding arms 111 and 112 connect the vibrating unit 120 and the holding unit 140. More specifically, the holding arm 111 has one end (the right end in FIG. 3) connected to the connecting portion 135C of the vibrating portion 120 and the other end (the left end in FIG. 3) connected to the frame body 140c.
  • the holding arm 112 is provided so that its longitudinal direction is parallel to the X axis. One end (the left end in FIG. 3) of the holding arm 112 is connected to the connecting portion 135C of the vibrating part 120, and the other end (the right end in FIG.
  • the holding arm 111 and the holding arm 112 are formed substantially symmetrically with respect to an imaginary plane P defined parallel to the YZ plane along the center line of the vibrating section 120 in the X-axis direction. ..
  • the width of the holding arm 111 and the holding arm 112 in the X-axis direction is, for example, about 10 ⁇ m.
  • the holding arm 111 and the holding arm 112 connect the vibrating section 120 to the holding section 140 along the center line of the vibrating section 120 in the Y-axis direction.
  • the first diaphragm 135A has one side with respect to the holding arms 111 and 112, that is, It is arranged on the Y axis positive direction side.
  • the second diaphragm 135B is arranged on the other side with respect to the holding arms 111 and 112, that is, on the Y axis negative direction side.
  • FIG. 3 shows an example in which the holding arm 111 and the holding arm 112 are formed substantially symmetrically with respect to the virtual plane P, the present invention is not limited to this.
  • the number of holding arms may be one, and in this case, the vibrating section 120 is cantilevered by the holding arm and held by the holding section 140.
  • the vibrating section 120 includes the first diaphragm 135A and the second diaphragm 135B that vibrate in the opposite phases with the out-of-plane bending vibration as the main vibration, and the first diaphragm 135A is The holding arms 111 and 112 are arranged on one side, and the second diaphragm 135B is arranged on the other side with respect to the holding arms 111 and 112. Accordingly, in the vibrating section 120, the connecting portion with the holding arms 111 and 112 serves as a fixed end, and the first vibrating plate 135A arranged on one side with respect to the holding arms 111 and 112 and the other side with respect to the holding arms 111 and 112. Since the second vibrating plate 135B is vibrated as a free end, the area of the vibrating region can be expanded as compared with the conventional resonator. Therefore, it is possible to suppress a decrease in electrostatic capacity and reduce an equivalent series capacity.
  • FIG. 4 is a sectional view schematically showing a configuration of a section taken along line IV-IV shown in FIG.
  • FIG. 5 is a sectional view showing a configuration for applying a voltage to the resonator 10.
  • FIG. 6 is a perspective view schematically showing a vibration mode of the resonator 10 shown in FIG.
  • the vibrating section 120 of the resonator 10 includes a piezoelectric thin film F3 on a silicon (Si) substrate (hereinafter referred to as “Si substrate”) F2, which is an example of a substrate, so as to cover the Si substrate F2.
  • Si substrate silicon
  • the metal layer E2 is laminated on the piezoelectric thin film F3.
  • the piezoelectric thin film F3 is laminated on the metal layer E2 so as to cover the metal layer E2, and the metal layer E1 is further laminated on the piezoelectric thin film F3.
  • the piezoelectric thin film F3, the metal layer E2, and the metal layer E1 of the present embodiment correspond to an example of the “piezoelectric layer” of the present invention.
  • the mechanical strength of the vibrating section 120 can be increased.
  • the Si substrate F2 may be formed of, for example, a degenerate n-type silicon (Si) semiconductor having a thickness of about 6 ⁇ m.
  • the degenerate silicon (Si) can contain phosphorus (P), arsenic (As), antimony (Sb), or the like as an n-type dopant.
  • the resistance value of the degenerate silicon (Si) used for the Si substrate F2 is, for example, less than 16 m ⁇ cm, and more preferably 1.2 m ⁇ cm or less.
  • the frequency temperature characteristic can be improved.
  • an insulating layer F21 is arranged between the upper surface of the Si substrate F2 and the piezoelectric thin film F3.
  • the insulating layer F21 is formed using an insulating film such as silicon dioxide (SiO 2 ).
  • the insulating layer F21 has a thickness of, for example, about 0.5 ⁇ m.
  • correction layer F22 is arranged on the lower surface of the Si substrate F2, that is, on the opposite side of the insulating layer F21 with the Si substrate F2 interposed therebetween.
  • the correction layer F22 is formed by using, for example, silicon dioxide (eg, SiO 2 ).
  • the correction layer F22 is a temperature coefficient of the frequency in the vibrating section 120 when the correction layer is formed on the Si substrate F2, that is, the temperature, as compared with the case where the correction layer F22 is not formed on the Si substrate F2.
  • the metal layers E1 and E2 have a thickness of, for example, 0.1 ⁇ m or more and 0.2 ⁇ m or less, and are patterned into a desired shape by etching or the like after the film formation.
  • the metal layers E1 and E2 are made of a metal whose crystal structure is a body-centered cubic structure. Specifically, the metal layers E1 and E2 are formed using Mo (molybdenum), tungsten (W), or the like.
  • the metal layer E1 is formed, for example, on the vibrating portion 120 so as to serve as an upper electrode.
  • the metal layer E1 is formed on the holding arms 111 and 112 and the holding portion 140 so as to function as a wiring for connecting the upper electrode to an AC power supply provided outside the resonator 10. ..
  • the metal layer E2 is formed on the vibrating portion 120 so as to serve as a lower electrode. Further, the metal layer E2 is formed on the holding arm 110 and the holding portion 140 so as to serve as a wiring for connecting the lower electrode to a circuit provided outside the resonator 10.
  • the Si substrate F2 itself can also serve as the lower electrode, and the metal layer E2 can be omitted.
  • the piezoelectric thin film F3 is a piezoelectric thin film that converts an applied voltage into vibration.
  • the piezoelectric thin film F3 is formed of a material having a wurtzite type hexagonal crystal structure, and includes, for example, aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), A nitride or oxide such as indium nitride (InN) can be the main component.
  • scandium aluminum nitride is obtained by replacing a part of aluminum in aluminum nitride with scandium, and instead of scandium, magnesium (Mg) and niobium (Nb) or magnesium (Mg) and zirconium (Zr) and the like 2 are used. It may be substituted with an element.
  • the piezoelectric thin film F3 has a thickness of, for example, 1 ⁇ m, but it is also possible to use a thickness of about 0.2 ⁇ m to 2 ⁇ m.
  • the resonance device 1 includes a set of external electrodes (not shown), a voltage is applied from the external electrodes to the metal layers E1 and E2, and in response to an electric field applied to the piezoelectric thin film F3 by the metal layers E1 and E2,
  • the piezoelectric thin film F3 expands and contracts in the in-plane direction of the XY plane, that is, in the Y-axis direction. Due to the expansion and contraction of the piezoelectric thin film F3, the first diaphragm 135A and the second diaphragm 135B displace their free ends toward the inner surfaces of the lower lid 20 and the upper lid 30, respectively, and vibrate in the out-of-plane bending vibration mode. ..
  • the phase of the electric field applied to the first diaphragm 135A and the phase of the electric field applied to the second diaphragm 135B are set to be opposite to each other. There is. As a result, as shown in FIG. 6, the first diaphragm 135A and the second diaphragm 135B are displaced in opposite directions. For example, when the first diaphragm 135A displaces the free end toward the Z axis positive direction toward the inner surface of the upper lid 30, the second diaphragm 135B moves the free end toward the Z axis negative direction toward the inner surface of the lower lid 20. Displace. In FIG. 6, a light-colored area indicates that the displacement due to vibration is small, and a dark-colored area indicates that the displacement due to vibration is large.
  • the connecting portion 135C is a fixed end of the first diaphragm 135A and the second diaphragm 135B, it serves as a node in the vibrating portion 120. Further, in the connecting portion 135C, since the first vibrating plate 135A and the second vibrating plate 135B are held by the holding portion 140 by the holding arms 111 and 112, when the first vibrating plate 135A and the second vibrating plate 135B vibrate, they vibrate. It is possible to reduce the retention loss or anchor loss of the.
  • the first vibrating plate 135A and the second vibrating plate 135B are held by the holding portion 140 by the holding arms 111 and 112 that connect the connecting portion 135C and the holding portion 140, so that the vibrating portion 120 becomes Y. Since it is held at the center in the axial direction, it is possible to suppress a decrease in Q value due to vibration holding loss or anchor loss.
  • the length L in the Y-axis direction of each of the first diaphragm 135A and the second diaphragm 135B shown in FIGS. 3 and 4 may be set to 1/2 times the wavelength ⁇ in the out-of-plane bending vibration. preferable. This makes it possible to easily realize the vibrating section 120 that suppresses a decrease in electrostatic capacitance.
  • FIG. 7 is a graph showing the relationship between the frequency and the Q value depending on the thermoelastic loss in the virtual vibration part that does not include the insulating layer F21 shown in FIG.
  • FIG. 8 is a graph showing the relationship between the frequency and the Q value depending on the thermoelastic loss in the vibrating section 120 including the insulating layer F21 shown in FIG.
  • the values when the thickness of the Si substrate F2 shown in FIG. 4 is 5 ⁇ m, 10 ⁇ m, 20 ⁇ m, and 30 ⁇ m are plotted, respectively.
  • the Q value of the resonance vibration in the resonator 10 (hereinafter, simply referred to as “Q value”) is mainly due to thermoelastic loss (TED: Thermoelastic Damping) in the resonance frequency range of 10 MHz or less. I know that. Therefore, it is desirable that the vibrating section 120 has a structure that reduces this thermoelastic loss.
  • TED Thermoelastic Damping
  • both graphs have an inflection point at a certain frequency.
  • the frequency range lower than the inflection point the smaller the thickness of the Si substrate F2, the higher the Q value. That is, in this frequency range, the shorter the heat transfer time, the higher the Q value.
  • the frequency range higher than the inflection point the larger the thickness of the Si substrate F2, the higher the Q value. That is, in this frequency range, the longer the heat transfer time, the higher the Q value.
  • FIG. 7 shows a graph of a virtual vibrating portion not including the insulating layer F21 shown in FIG. 4
  • silicon dioxide (SiO 2 ) which is the main component of the insulating layer F21 has a thermal conductivity of 1.4 [W/(m/K)], which is higher than that of other materials. It is known to be extremely low.
  • the insulating layer F21 is arranged on the upper surface of the Si substrate F2, in other words, near the center of the vibrating portion 120 in the thickness direction. In this case, the heat conduction time becomes longer than in the case where the insulating layer F21 is arranged at another position.
  • the insulating layer F21 containing silicon dioxide (SiO 2 ) as a main component between the Si substrate F2 and the piezoelectric thin film F3 it is possible to suppress the decrease in Q value and to reduce the thermoelastic loss ( It is particularly remarkable in the range of 1 MHz or more and 10 MHz or less where TED) becomes a main factor or bottleneck of the Q value.
  • FIG. 9 is a graph showing the relationship between the aspect ratio W/L and the electromechanical coupling coefficient k.
  • the length L of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is 0.10 mm, 0.13 mm, 0.16 mm, and 0.18 mm.
  • the values are plotted respectively.
  • a light-colored area indicates a small displacement due to vibration
  • a dark-colored area indicates a large displacement due to vibration.
  • the electromechanical coupling coefficient k periodically decreases when the aspect ratio W/L is 1.0, 3.0, and 5.0.
  • the vibrating portion 120B showing the vibrating state when the aspect ratio W/L is 1.0, not only the out-of-plane bending vibration in the length L direction but also the out-of-plane bending vibration in the width W direction occurs. I understand that.
  • the frequency of the out-of-plane bending vibration in the direction of the length L and the frequency of the out-of-plane bending vibration in the direction of the width W are the same. It is considered that the electromechanical coupling coefficient k decreases due to the change.
  • the aspect ratio W/L is 3.0 or 5.0
  • the frequency of the out-of-plane bending vibration in the length L direction and the frequency of the third or fifth harmonic of the out-of-plane bending vibration in the width W direction decreases due to the coincidence and coupling.
  • the aspect ratio W/L is 0.1 ⁇ W/L ⁇ 0.9, or 2n ⁇ 0.8 ⁇ W/L ⁇ 2n+0, avoiding a value of 2n ⁇ 1 (n is a natural number). It is set in the range of 0.9. This can prevent coupling with an unnecessary vibration mode. Therefore, the reduction of the electromechanical coupling coefficient k can be suppressed.
  • FIG. 10 is a graph showing the relationship between the ratio Le/L and the electromechanical coupling coefficient k.
  • the values when the aspect ratio W/L is set to 0.6 and 4.0 are plotted.
  • the graph shown in FIG. 10 shows that in the vibrating section 120, the length L is 0.10 mm, the Si substrate F2 has a thickness of 10 ⁇ m, the insulating layer F21 has a thickness of 0.5 ⁇ m, and the metal layers E1 and E2 have thicknesses. Is 0.2 ⁇ m and the piezoelectric thin film F3 is 0.8 ⁇ m.
  • the value of the electromechanical coupling coefficient k is relatively high when the ratio Le/L is 0.3 or more, more preferably 0.5 or more.
  • the electromechanical coupling coefficient k is maximized around the ratio Le/L of 0.6.
  • the ratio Le/L is set in the range of 0.3 ⁇ Le/L ⁇ 1.0. Thereby, the electromechanical coupling coefficient k can be increased.
  • the length L of the first diaphragm 135A and the second diaphragm 135B shown in FIGS. 3 and 4 is set to 1/2 times the wavelength ⁇ in the out-of-plane bending vibration.
  • the length L of the first diaphragm 135A and the second diaphragm 135B may be set to m/2 (m is a positive integer of 2 or more) times the wavelength ⁇ in the out-of-plane bending vibration.
  • FIG. 11 and 12 are perspective views schematically showing a vibration mode of a modified example of the vibrating section 120 shown in FIG.
  • a light-colored area indicates a small displacement due to vibration
  • a dark-colored area indicates a large displacement due to vibration. It is shown that.
  • the length L of the first vibrating plate 135A and the second vibrating plate 135B is set to 3/2 times the wavelength ⁇ in the out-of-plane bending vibration.
  • the first vibrating plate 135A and the second vibrating plate 135B of the vibrating section 120H are each driven by the third harmonic of the out-of-plane bending vibration.
  • first diaphragm 135A and the second diaphragm 135B are not limited to being driven by the odd harmonics of the out-of-plane bending vibration, and may be driven by the even harmonics of the out-of-plane bending vibration. ..
  • the length L of the first vibrating plate 135A and the second vibrating plate 135B is set to the same value as the wavelength ⁇ in the out-of-plane bending vibration.
  • the first vibrating plate 135A and the second vibrating plate 135B of the vibrating section 120I are each driven by the second harmonic of the out-of-plane bending vibration.
  • the length L of each of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is m/2 (m is a positive integer of 2 or more) times the wavelength ⁇ in the out-of-plane bending vibration.
  • the area of the vibration region can be further expanded.
  • the first diaphragm 135A and the second diaphragm 135B have a rectangular shape in plan view
  • the first diaphragm 135A and the second diaphragm 135B may each have a shape other than a rectangle.
  • the example in which the vibrating section 120 includes the two first vibrating plates 135A and the second vibrating plate 135B is shown, but the present invention is not limited to this.
  • the vibrating section 120 may include another vibrating plate in addition to the first vibrating plate 135A and the second vibrating plate 135B.
  • ⁇ Second Modification> 13 to 17 are plan views showing modified examples of the vibrating section 120 shown in FIG. Note that the cross section taken along the line AA′ shown in FIGS. 13 to 17 is the same as the cross section shown in FIG. 4, and therefore illustration and description of the configuration thereof will be omitted.
  • the first vibrating plate 135A and the second vibrating plate 135B each have a substantially trapezoidal shape. Specifically, in the first diaphragm 135A, the side facing the frame 140a is shorter and the width of the free end is narrower than the side of the connecting portion 135C. Similarly, in the second diaphragm 135B, the side facing the frame 140b is shorter and the width of the free end is narrower than the side of the connecting portion 135C. Further, in the vibrating section 120K shown in FIG. 14, each of the first vibrating plate 135A and the second vibrating plate 135B has a substantially triangular shape.
  • each of the first vibrating plate 135A and the second vibrating plate 135B has a substantially inverted trapezoidal shape. Specifically, in the first diaphragm 135A, the side facing the frame 140a is longer and the width of the free end is wider than the side of the connecting portion 135C. Similarly, in the second diaphragm 135B, the side facing the frame 140b is longer and the width of the free end is wider than the side of the connecting portion 135C.
  • the vibrating section 120M shown in FIG. 16 includes a first vibrating plate 135A and a second vibrating plate 135B, and a third vibrating plate 135D having a rectangular flat plate shape.
  • the first vibrating plate 135A and the third vibrating plate 135D are arranged with a predetermined width apart in the X-axis direction.
  • the end of the first diaphragm 135A on the negative Y-axis side and the end of the third diaphragm 135D on the negative Y-axis side are connected to the end of the second diaphragm 135B on the positive Y-axis side.
  • a connecting portion 135C is formed.
  • the first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG. 16, and the third diaphragm 135D and the third diaphragm 135D
  • the two vibrating plates 135B vibrate in opposite phases in the XY plane in the orthogonal coordinate system shown in FIG. 16 with the out-of-plane bending vibration mode as the main vibration.
  • the vibrating section 120N shown in FIG. 17 includes, in addition to the first vibrating plate 135A and the second vibrating plate 135B, a third vibrating plate 135D and a fourth vibrating plate 135E having a rectangular flat plate shape.
  • the first vibrating plate 135A and the third vibrating plate 135D are arranged with a predetermined width apart in the X-axis direction.
  • the second vibrating plate 135B and the fourth vibrating plate 135E are spaced apart by a predetermined width in the X-axis direction.
  • the vibrating section 120M further includes a connecting arm 136, and the connecting arm 136 connects the first vibrating plate 135A and the second vibrating plate 135B to the third vibrating plate 135D and the fourth vibrating plate 135E.
  • the first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG. 16, and the third diaphragm 135D and the third diaphragm 135D
  • the four vibrating plates 135E vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG.
  • FIG. 3 an example in which the holding arms 111 and 112 have a rectangular shape in plan view is shown in FIG. 3, but the present invention is not limited to this. Other forms may be used as long as they connect the vibrating part 120 and the holding part 140.
  • FIGS. 18 and 19 are plan views showing modified examples of the resonator 10 shown in FIG. Note that the cross section taken along the line BB′ shown in FIGS. 18 and 19 is the same as the cross section shown in FIG. 4, and therefore illustration and description of the configuration thereof will be omitted.
  • the resonator 10A shown in FIG. 18 includes holding units 111A and 112A instead of the holding arms 111 and 112 shown in FIG.
  • the holding unit 111A includes the vibration damping portion 4a
  • the holding unit 112A includes the vibration damping portion 4b.
  • the vibration damping portions 4a and 4b respectively project to the Y-axis positive direction side and the Y-axis negative direction side.
  • the vibration buffers 4a and 4b are respectively connected to the vibration part 120 by the arm 111a and connected to the holding part 140 by the arm 111b.
  • the holding units 111A and 112A include the vibration damping portions 4a and 4b, it is possible to efficiently trap the harmonic vibration of the out-of-plane bending vibration that has propagated from the vibrating portion 120.
  • the holding unit 111A includes the vibration damping portion 4a, and the holding unit 112A includes the vibration damping portion 4b.
  • the resonator 10B shown in FIG. 19 includes holding units 111B and 112B instead of the holding arms 111 and 112 shown in FIG.
  • the holding unit 111B includes a node generation unit 130A
  • the holding unit 112B includes a node generation unit 130B.
  • Each of the node generation units 130A and 130B is connected to the vibrating unit 120 by an arm 111a and connected to the holding unit 140 by an arm 111b.
  • the node generation unit 130A has a side 131a facing the long side of the vibrating unit 120, and is connected to the arm 111a at the side 131a.
  • the node generation unit 130B has a side 131b facing the long side of the vibrating unit 120, and is connected to the arm 111a at the side 131b.
  • Each of the node generation units 130A and 130B has a shape in which the width along the X-axis direction becomes narrower from the arm 111a toward the arm 111b.
  • the node generation units 130A and 130B each have a line-symmetrical shape with respect to the vertical bisector of the side 131a.
  • Each of the node generation units 130A and 130B has a portion having the maximum width along the Y-axis direction on the arm 111a side with respect to the center in the X-axis direction.
  • the width of the node generation unit 130A along the Y-axis direction is the maximum on the side 131a and gradually narrows from the arm 111a to the arm 111b, and the apex and the arm of the node generation unit 130A. It becomes the narrowest at the connection point with 111b.
  • the widths of the node generators 130A and 130B along the Y-axis direction do not need to be continuously narrowed, and for example, even if the widths are gradually narrowed or partially widened, It should be gradually narrowed as a whole.
  • the peripheral edges of the node generating units 130A and 130B are not limited to the smooth shape, and may have irregularities.
  • the node generation unit 130A has, for example, a semicircular shape having a diameter of the side 131a and a radius of about 30 ⁇ m.
  • the center of the circle forming the arc of the node generation unit 130A is located at the center of the side 131a.
  • the center of the circle forming the arc of the node generation unit 130A may be located at the center of the arm 111b.
  • the side 131a is not limited to a straight line shape, but may be an arc shape.
  • the arm 111a is connected to the apex of the side 131a.
  • the center of the circle forming the arc of the side 131a may be located on the arm 111a side or the arm 111b side.
  • the length of the side 131a is preferably larger than the width of the arm 111a along the Y-axis direction and smaller than the long side of the vibrating section 120. Since the same applies to the node generation unit 130B, the description thereof will be omitted.
  • the node generation unit 130A of the holding unit 111B and the node generation unit 130B of the holding unit 112B in the present embodiment each have a structure in which the width along the X-axis direction gradually narrows from the arm 111a toward the arm 111b. is there. Therefore, even when the propagation state of the vibration propagating from the vibrating unit 120 changes, the node generating units 130A and 130B each have a small displacement region adjacent to a large displacement region due to the vibration. To be done. Accordingly, the node generation units 130A and 130B can adjust the displacement parts with respect to the vibration leaked from the vibration unit 120 and form the vibration nodes on the node generation units 130A and 130B, respectively.
  • the node generation units 130A and 130B can suppress the propagation of vibration from the vibration unit 120 to the holding unit 140 by being connected to the arms 111a at the formed nodes. As a result, the anchor loss of the resonator 10B can be reduced and the Q value can be improved.
  • FIG. 20 is a graph showing the relationship between the aspect ratio W/L and the electromechanical coupling coefficient k.
  • FIG. 21 is a graph showing the relationship between the aspect ratio W/L and the displacement amount of the holding unit.
  • the length L of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is 0.10 mm, 0.13 mm, 0.16 mm, and 0.18 mm. The values at each time are plotted.
  • a light-colored area indicates that the displacement due to vibration is small, and a dark-colored area indicates that the displacement due to vibration is large.
  • the vertical axis of FIG. 21 shows a value obtained by performing area integration on the displacement amount at the connecting surface between the holding unit and the holding portion, and the unit is mm 3 .
  • This value is an index indicating vibration leakage. That is, the greater the displacement of the connecting surface between the holding unit and the holding unit, the more the vibration propagates to the holding unit and the Q value decreases.
  • the vibrating section 120S has a high electromechanical coupling coefficient k, but the displacement of the holding unit is large, so vibration leakage is large.
  • the vibrating portion 120S flexurally vibrates in the length L direction of the first vibrating plate 135A and the second vibrating plate 135B, and this vibration mode is referred to as the LB mode.
  • the WB mode is a vibration mode in which bending vibration occurs in the width W direction of the first diaphragm 135A and the second diaphragm 135B, and the vibration confinement is high.
  • the vibrating sections 120R, 120T, and 120V each vibrate in the CB mode, which is the combined vibration of the LB mode and the WB node.
  • the vibrating portion 120R has an aspect ratio W/L of 1.4
  • the vibrating portion 120T has an aspect ratio W/L of 3.2
  • the vibrating portion 120V has an aspect ratio W/L of 4.9.
  • the vibrating portions 120R, 120T, and 120V have high electromechanical coupling coefficient k and small displacement amount of the holding unit, respectively, so that high electromechanical coupling coefficient k and vibration confinement are achieved. It has both sex. Therefore, a high Q value can be expected in the vibrating sections 120R, 120T, 120V.
  • the vibrating portion includes a first vibrating plate and a second vibrating plate that vibrate in opposite phases with the out-of-plane bending vibration as a main vibration.
  • the first diaphragm is arranged on one side with respect to the holding arm
  • the second diaphragm is arranged on the other side with respect to the holding arm.
  • the connecting portion with the holding arm serves as a fixed end
  • the first diaphragm arranged on one side of the holding arm and the second diaphragm arranged on the other side of the holding arm serve as free ends. Since it vibrates, the area of the vibrating region can be expanded as compared with the conventional resonator. Therefore, it is possible to suppress a decrease in electrostatic capacity and reduce an equivalent series capacity.
  • the connecting portion connects the first diaphragm and the second diaphragm
  • the holding arm connects the connecting portion and the holding portion.
  • the ratio W/L of the width W in the X-axis direction to the length L in the Y-axis direction of each of the first diaphragm and the second diaphragm is 0.1 ⁇ W/L ⁇ 0. .9, or 2n ⁇ 0.8 ⁇ W/L ⁇ 2n+0.9. This can prevent coupling with an unnecessary vibration mode. Therefore, the reduction of the electromechanical coupling coefficient k can be suppressed.
  • the ratio Le/L of the length Le in the Y-axis direction of the metal layer to the length L in the Y-axis direction of each of the first diaphragm and the second diaphragm is 0.3 ⁇ Le. /L ⁇ 1.0 is set.
  • the electromechanical coupling coefficient k can be increased.
  • the length L of each of the first diaphragm and the second diaphragm in the Y-axis direction is set to 1/2 the wavelength of the out-of-plane bending vibration.
  • the length L of each of the first diaphragm and the second diaphragm in the Y-axis direction is m/2 (m is a positive integer of 2 or more) times the wavelength in the out-of-plane bending vibration.
  • the insulating layer containing silicon dioxide (SiO 2 ) as a main component between the Si substrate and the piezoelectric thin film it is possible to suppress the Q value from decreasing and to reduce the thermoelastic loss. It is particularly remarkable in the range of 1 MHz or more and 10 MHz or less where (TED) is the main factor or bottleneck of the Q value.
  • the material of the substrate of the vibration part is silicon (Si).
  • the material of the substrate of the vibrating portion 120 is degenerate silicon (Si). As a result, the frequency temperature characteristic can be improved.
  • the correction layer is arranged on the opposite side of the insulating layer with the Si substrate interposed therebetween.
  • the vibrating portion includes a piezoelectric thin film. This makes it possible to easily realize a vibrating portion that causes out-of-plane bending vibration.
  • the vibrating portion further includes another metal layer. This makes it possible to more easily realize a vibrating portion that causes out-of-plane bending vibration.
  • a resonance device includes the resonator described above, a lower lid and an upper lid that form a vibration space of the resonator, and an external electrode. As a result, it is possible to easily realize a resonance device that suppresses a decrease in capacitance.

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Abstract

The present invention suppresses degradation in electrostatic capacitance in a resonator having an out-of-plane bending vibration as a main vibration. This resonator 10 is provided with: a vibration unit 120 including a first vibration plate 135A and a second vibration plate 135B each of which vibrates in a reverse phase with an out-of-plane bending vibration as a main vibration; a holding unit 140 formed so as to surround at least a portion of the vibration unit 120; and holding arms 111, 112 that connect the vibration unit 120 and the holding unit 140, wherein when the main surface of the vibration unit 120 is viewed from the top, the first vibration plate 135A is disposed on one side with respect to the holding arms 111, 112, and the second vibration plate 135B is disposed on the other side with respect to the holding arms 111, 112.

Description

共振子及び共振装置Resonator and resonance device
　本発明は、面外屈曲振動モードで振動する共振子及び共振装置に関する。 The present invention relates to a resonator and a resonance device that vibrate in an out-of-plane bending vibration mode.
　従来、ＭＥＭＳ（Ｍｉｃｒｏ　Ｅｌｅｃｔｒｏ　Ｍｅｃｈａｎｉｃａｌ　Ｓｙｓｔｅｍｓ）技術を用いた共振装置が例えばタイミングデバイスとして用いられている。この共振装置は、スマートフォンなどの電子機器内に組み込まれるプリント基板上に実装される。共振装置は、下側基板と、下側基板との間でキャビティを形成する上側基板と、下側基板及び上側基板の間でキャビティ内に配置された共振子と、を備えている。 Conventionally, a resonance device using a MEMS (Micro Electro Mechanical Systems) technology has been used as a timing device, for example. This resonant device is mounted on a printed circuit board incorporated in an electronic device such as a smartphone. The resonator device includes a lower substrate, an upper substrate that forms a cavity between the lower substrate, and a resonator disposed in the cavity between the lower substrate and the upper substrate.
　例えば特許文献１には、基部と、基部に一端が連ねられており、Ｙ方向に延びる複数の音叉腕とを備え、当該複数の音叉腕は、Ｙ方向と直交するＸ方向に並列されており、音叉腕が、Ｘ方向及びＹ方向と直交するＺ方向に屈曲振動する振動装置が開示されている。 For example, in Patent Document 1, a base portion and a plurality of tuning fork arms each having one end connected to the base portion and extending in the Y direction are provided, and the plurality of tuning fork arms are arranged in parallel in the X direction orthogonal to the Y direction. There is disclosed a vibrating device in which a tuning fork arm vibrates in a Z direction orthogonal to the X direction and the Y direction.
特許第６０９４６７２号公報Japanese Patent No. 6094672
　通常、特許文献１に記載されるような共振子又は共振装置は、共振周波数が１００ｋＨｚ以下の範囲で使用されている。このような共振子又は共振装置を、１００ｋＨｚより高い共振周波数で使用する場合、共振周波数を高くするために、音叉腕において、長さを短くして厚さを大きくする必要がある。その結果、振動部の面積が小さくなってしまい、振動部の静電容量が小さくなっていた。 Normally, the resonator or the resonance device as described in Patent Document 1 is used in the range of the resonance frequency of 100 kHz or less. When using such a resonator or a resonance device at a resonance frequency higher than 100 kHz, it is necessary to shorten the length and increase the thickness of the tuning fork arm in order to increase the resonance frequency. As a result, the area of the vibrating portion is reduced, and the electrostatic capacitance of the vibrating portion is reduced.
　本発明はこのような事情に鑑みてなされたものであり、静電容量の低下を抑制することのできる共振子及び共振装置を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a resonator and a resonance device capable of suppressing a decrease in electrostatic capacitance.
　本発明の一側面に係る共振子は、
　面外屈曲振動を主振動としてそれぞれが逆位相で振動する第１振動部及び第２振動部を含む振動部と、
　振動部の少なくとも一部を囲むように形成される保持部と、
　振動部と保持部とを接続する保持ユニットと、を備え、
　振動部の主面を平面視したときに、第１振動部が保持ユニットに関して一方側に配置され、第２振動部が保持ユニットに関して他方側に配置される。 A resonator according to one aspect of the present invention is
A vibrating section including a first vibrating section and a second vibrating section, each of which vibrates in an opposite phase with the out-of-plane bending vibration as a main vibration;
A holding portion formed so as to surround at least a part of the vibrating portion,
A holding unit that connects the vibrating unit and the holding unit,
When the main surface of the vibrating portion is viewed in a plan view, the first vibrating portion is arranged on one side with respect to the holding unit, and the second vibrating portion is arranged on the other side with respect to the holding unit.
　本発明の一側面に係る共振装置は、
　前述した共振子と、
　共振子の振動空間を形成する蓋体と、
　外部電極と、を備える。 A resonance device according to one aspect of the present invention is
The resonator described above,
A lid that forms the vibration space of the resonator,
And an external electrode.
　本発明によれば、静電容量の低下を抑制することができる。 According to the present invention, a decrease in capacitance can be suppressed.
図１は、本発明の第１実施形態に係る共振装置の外観を概略的に示す斜視図である。FIG. 1 is a perspective view schematically showing the outer appearance of a resonance device according to a first embodiment of the present invention. 図２は、図１に示した共振装置の構造を概略的に示す分解斜視図である。FIG. 2 is an exploded perspective view schematically showing the structure of the resonance device shown in FIG. 図３は、図２に示した共振子の構造を概略的に示す平面図である。FIG. 3 is a plan view schematically showing the structure of the resonator shown in FIG. 図４は、図３に示したＩＶ－ＩＶ線に沿った断面の構成を概略的に示す断面図である。FIG. 4 is a sectional view schematically showing a configuration of a section taken along line IV-IV shown in FIG. 図５は、図３に示したＶ－Ｖ線に沿った断面の構成を概略的に示す断面図である。FIG. 5 is a sectional view schematically showing a configuration of a section taken along the line VV shown in FIG. 図６は、図３に示した共振子の振動態様を模式的に示す斜視図である。FIG. 6 is a perspective view schematically showing a vibration mode of the resonator shown in FIG. 図７は、図４に示した絶縁層を含まない仮想的な振動部における周波数と熱弾性減衰に依存するＱ値との関係を示すグラフである。FIG. 7 is a graph showing the relationship between the frequency and the Q value depending on thermoelastic damping in the virtual vibrating portion that does not include the insulating layer shown in FIG. 図８は、図４に示した絶縁層を含む振動部における周波数と熱弾性減衰に依存するＱ値との関係を示すグラフである。FIG. 8 is a graph showing the relationship between the frequency and the Q value depending on thermoelastic damping in the vibration part including the insulating layer shown in FIG. 図９は、アスペクト比と電気機械結合係数との関係を示すグラフである。FIG. 9 is a graph showing the relationship between the aspect ratio and the electromechanical coupling coefficient. 図１０は、励振電極長と共振部長の比と電気機械結合係数との関係を示すグラフである。FIG. 10 is a graph showing the relationship between the ratio of the excitation electrode length to the resonance portion length and the electromechanical coupling coefficient. 図１０は、図６に示した振動部の変形例の振動態様を模式的に示す斜視図である。FIG. 10 is a perspective view schematically showing a vibration mode of a modified example of the vibrating section shown in FIG. 図１２は、図６に示した振動部の変形例の振動態様を模式的に示す斜視図である。FIG. 12 is a perspective view schematically showing a vibration mode of a modification of the vibrating section shown in FIG. 図１３は、図３に示した振動部の変形例を示す平面図である。FIG. 13 is a plan view showing a modified example of the vibrating section shown in FIG. 図１４は、図３に示した振動部の変形例を示す平面図である。FIG. 14 is a plan view showing a modified example of the vibrating section shown in FIG. 図１５は、図３に示した振動部の変形例を示す平面図である。FIG. 15 is a plan view showing a modified example of the vibrating section shown in FIG. 図１６は、図３に示した振動部の変形例を示す平面図である。FIG. 16 is a plan view showing a modified example of the vibrating section shown in FIG. 図１７は、図３に示した振動部の変形例を示す平面図である。FIG. 17 is a plan view showing a modification of the vibrating section shown in FIG. 図１８は、図３に示した共振子の変形例を示す平面図である。FIG. 18 is a plan view showing a modification of the resonator shown in FIG. 図１９は、図３に示した共振子の変形例を示す平面図である。FIG. 19 is a plan view showing a modification of the resonator shown in FIG. 図２０は、アスペクト比と電気機械結合係数との関係を示すグラフである。FIG. 20 is a graph showing the relationship between the aspect ratio and the electromechanical coupling coefficient. 図２１は、アスペクト比と保持ユニットの変位量との関係を示すグラフである。FIG. 21 is a graph showing the relationship between the aspect ratio and the amount of displacement of the holding unit.
　以下に本発明の実施形態を説明する。以下の図面の記載において、同一又は類似の構成要素は同一又は類似の符号で表している。図面は例示であり、各部の寸法や形状は模式的なものであり、本発明の技術的範囲を当該実施形態に限定して解するべきではない。 An embodiment of the present invention will be described below. In the following description of the drawings, the same or similar components are represented by the same or similar reference numerals. The drawings are examples, and the dimensions and shapes of the respective parts are schematic, and the technical scope of the present invention should not be limited to the embodiments.
　［第１実施形態］
　まず、図１及び図２を参照しつつ、本発明の第１実施形態に係る共振装置の概略構成について説明する。図１は、本発明の第１実施形態に係る共振装置１の外観を概略的に示す斜視図である。図２は、図１に示した共振装置１の構造を概略的に示す分解斜視図である。 [First Embodiment]
First, a schematic configuration of a resonance apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view schematically showing the outer appearance of a resonance device 1 according to the first embodiment of the present invention. FIG. 2 is an exploded perspective view schematically showing the structure of the resonance device 1 shown in FIG.
　共振装置１は、共振子１０と、下蓋２０及び上蓋３０と、を備えている。すなわち、共振装置１は、下蓋２０と、共振子１０と、上蓋３０とが、この順で積層されて構成されている。なお、本実施形態の下蓋２０及び上蓋３０は、本発明の「蓋体」の一例に相当する。 The resonance device 1 includes a resonator 10, and a lower lid 20 and an upper lid 30. That is, the resonance device 1 is configured by stacking the lower lid 20, the resonator 10, and the upper lid 30 in this order. The lower lid 20 and the upper lid 30 of this embodiment correspond to an example of the “lid” of the present invention.
　以下において、共振装置１の各構成について説明する。なお、以下の説明では、共振装置１のうち上蓋３０が設けられている側を上（又は表）、下蓋２０が設けられている側を下（又は裏）、とする。 Each configuration of the resonance device 1 will be described below. In the following description, the side of the resonance device 1 where the upper lid 30 is provided is the top (or front), and the side where the lower lid 20 is provided is the bottom (or back).
　共振子１０は、ＭＥＭＳ技術を用いて製造されるＭＥＭＳ振動子である。共振子１０の共振周波数は、例えば１ＭＨｚ以上１０ＭＨｚ以下の範囲で好適である。共振子１０と下蓋２０及び上蓋３０とは、接合されている。また、共振子１０と下蓋２０及び上蓋３０とは、それぞれシリコン（Ｓｉ）基板（以下、「Ｓｉ基板」という）を用いて形成されており、Ｓｉ基板同士が互いに接合されている。なお、共振子１０及び下蓋２０は、ＳＯＩ基板を用いて形成されてもよい。 The resonator 10 is a MEMS oscillator manufactured using the MEMS technology. The resonance frequency of the resonator 10 is preferably in the range of 1 MHz or more and 10 MHz or less. The resonator 10, the lower lid 20 and the upper lid 30 are joined together. The resonator 10, the lower lid 20, and the upper lid 30 are each formed using a silicon (Si) substrate (hereinafter referred to as “Si substrate”), and the Si substrates are bonded to each other. The resonator 10 and the lower lid 20 may be formed using an SOI substrate.
　上蓋３０はＸＹ平面に沿って平板状に広がっており、その裏面に例えば平たい直方体形状の凹部３１が形成されている。凹部３１は、側壁３３に囲まれており、共振子１０が振動する空間である振動空間の一部を形成する。なお、上蓋３０は凹部３１を有さず、平板状の構成でもよい。また、上蓋３０の凹部３１の共振子１０側の面には、ゲッター層が形成されていてもよい。 The upper lid 30 spreads in a flat plate shape along the XY plane, and a flat rectangular parallelepiped recess 31 is formed on the back surface thereof. The recess 31 is surrounded by the side wall 33 and forms a part of a vibration space in which the resonator 10 vibrates. Note that the upper lid 30 does not have the recess 31 and may have a flat plate configuration. Further, a getter layer may be formed on the surface of the recess 31 of the upper lid 30 on the resonator 10 side.
　下蓋２０は、ＸＹ平面に沿って設けられる矩形平板状の底板２２と、底板２２の周縁部からＺ軸方向、つまり、下蓋２０と共振子１０との積層方向、に延びる側壁２３と、を有する。下蓋２０には、共振子１０と対向する面において、底板２２の表面と側壁２３の内面とによって形成される凹部２１が形成されている。凹部２１は、共振子１０の振動空間の一部を形成する。なお、下蓋２０は凹部２１を有さず、平板状の構成でもよい。また、下蓋２０の凹部２１の共振子１０側の面には、ゲッター層が形成されてもよい。 The lower lid 20 has a rectangular flat plate-shaped bottom plate 22 provided along the XY plane, and a side wall 23 extending from the peripheral portion of the bottom plate 22 in the Z-axis direction, that is, in the stacking direction of the lower lid 20 and the resonator 10. Have. On the surface of the lower lid 20 facing the resonator 10, a recess 21 formed by the surface of the bottom plate 22 and the inner surface of the side wall 23 is formed. The recess 21 forms a part of the vibration space of the resonator 10. The lower lid 20 does not have the recess 21 and may have a flat plate configuration. Further, a getter layer may be formed on the surface of the recess 21 of the lower lid 20 on the resonator 10 side.
　前述した上蓋３０と下蓋２０とによって、共振子１０の振動空間は気密に封止され、真空状態が維持される。なお、この振動空間には、例えば不活性ガス等の気体が充填されてもよい。 The vibration space of the resonator 10 is hermetically sealed by the above-described upper lid 30 and lower lid 20, and the vacuum state is maintained. The vibrating space may be filled with a gas such as an inert gas.
　次に、図３を参照しつつ、本発明の一実施形態に係る共振子１０の概略構成について説明する。図３は、図２に示した共振子１０の構造を概略的に示す平面図である。 Next, a schematic configuration of the resonator 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a plan view schematically showing the structure of the resonator 10 shown in FIG.
　図３に示すように、共振子１０は、ＭＥＭＳ技術を用いて製造されるＭＥＭＳ振動子である。共振子１０は、振動部１２０と、保持部１４０と、保持腕１１１，１１２と、を備える。なお、本実施形態の保持腕１１１，１１２は、本発明の「保持ユニット」の一例に相当する。 As shown in FIG. 3, the resonator 10 is a MEMS vibrator manufactured using the MEMS technology. The resonator 10 includes a vibrating section 120, a holding section 140, and holding arms 111 and 112. The holding arms 111 and 112 of this embodiment correspond to an example of the “holding unit” of the present invention.
　振動部１２０は、上蓋３０に対向する面を平面視（以下、単に「平面視」という）したときに、図３に示す直交座標系におけるＸＹ平面に沿って広がる矩形の輪郭を有している。振動部１２０は、保持部１４０の内側に設けられており、振動部１２０と保持部１４０との間には、所定の間隔で空間が形成されている。 The vibrating section 120 has a rectangular contour that spreads along the XY plane in the orthogonal coordinate system shown in FIG. 3 when the surface facing the upper lid 30 is viewed in plan (hereinafter, simply referred to as “plan view”). .. The vibrating section 120 is provided inside the holding section 140, and spaces are formed between the vibrating section 120 and the holding section 140 at predetermined intervals.
　振動部１２０は、第１振動板１３５Ａと、第２振動板１３５Ｂと、を含んでいる。第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、矩形平板状の形状を有している。第１振動板１３５ＡのＹ軸負方向側の端面と第２振動板１３５ＢのＹ軸正方向側の端面とは、連結しており、連結部１３５Ｃを形成している。なお、連結部１３５Ｃは、第１振動板１３５Ａ及び第２振動板１３５Ｂとは別の部材であってもよい。また、第１振動板１３５ＡのＹ軸負方向側の端面と第２振動板１３５ＢのＹ軸正方向側の端面とが連結され、連結部１３５Ｃを形成する場合に限定されるものではない。例えば、第１振動板１３５Ａ及び第２振動板１３５Ｂは、一体に形成された一つの板状部材であってもよい。 The vibrating section 120 includes a first vibrating plate 135A and a second vibrating plate 135B. The first diaphragm 135A and the second diaphragm 135B each have a rectangular flat plate shape. The end surface of the first vibrating plate 135A on the Y axis negative direction side and the end surface of the second vibrating plate 135B on the Y axis positive direction side are connected to each other to form a connecting portion 135C. The connecting portion 135C may be a member different from the first diaphragm 135A and the second diaphragm 135B. Further, it is not limited to the case where the end surface of the first diaphragm 135A on the Y axis negative direction side and the end surface of the second diaphragm 135B on the Y axis positive direction side are connected to each other to form the connecting portion 135C. For example, the first diaphragm 135A and the second diaphragm 135B may be a single plate-shaped member that is integrally formed.
　また、第１振動板１３５Ａ及び第２振動板１３５Ｂは、図３に示す直交座標系におけるＸＹ平面内で、面外屈曲振動モードを主振動としてそれぞれが逆位相で振動する。なお、第１振動板１３５Ａ及び第２振動板１３５Ｂの振動の詳細については、後述する。 Further, the first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG. The details of the vibration of the first diaphragm 135A and the second diaphragm 135B will be described later.
　図３に示すように、平面視において、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、Ｙ軸方向の長さＬ、Ｘ軸方向の幅Ｗの主面を有している。例えば、長さＬは１３０μｍ程度であり、幅Ｗは６０μｍ程度であり、その比（以下、「アスペクト比」ともいう場合がある）Ｗ／Ｌは０．４６程度である。 As shown in FIG. 3, in plan view, each of the first diaphragm 135A and the second diaphragm 135B has a main surface having a length L in the Y-axis direction and a width W in the X-axis direction. For example, the length L is about 130 μm, the width W is about 60 μm, and the ratio (hereinafter, also referred to as “aspect ratio”) W/L is about 0.46.
　また、後述するように、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、金属層Ｅ２を含んでいる。平面視において、各金属層Ｅ２のＸ軸方向の幅は、主面の幅Ｗと略同一であり、Ｙ軸方向に長さＬｅを有している。 Also, as will be described later, the first diaphragm 135A and the second diaphragm 135B each include a metal layer E2. In a plan view, the width of each metal layer E2 in the X-axis direction is substantially the same as the width W of the main surface, and has a length Le in the Y-axis direction.
　保持部１４０は、ＸＹ平面に沿って振動部１２０の外側を囲むように、矩形の枠状に形成される。なお、保持部１４０は、振動部１２０の周囲の少なくとも一部を囲むように設けられていればよく、枠状の形状に限定されるものではない。例えば、保持部１４０は、振動部１２０を保持し、また、上蓋３０及び下蓋２０と接合できる程度に、振動部１２０の周囲に設けられていればよい。 The holding portion 140 is formed in a rectangular frame shape so as to surround the outside of the vibrating portion 120 along the XY plane. It should be noted that the holding section 140 may be provided so as to surround at least a part of the periphery of the vibrating section 120, and is not limited to the frame-like shape. For example, the holding unit 140 may be provided around the vibrating unit 120 so that the holding unit 140 holds the vibrating unit 120 and can be joined to the upper lid 30 and the lower lid 20.
　本実施形態において、保持部１４０は一体形成される角柱形状の枠体１４０ａ～１４０ｄを含んでいる。枠体１４０ａは、第１振動板１３５Ａの開放端に対向して、長手方向がＸ軸に平行に設けられる。枠体１４０ｂは、第２振動板１３５Ｂの開放端に対向して、長手方向がＸ軸に平行に設けられる。枠体１４０ｃは、第１振動板１３５Ａ及び第２振動板１３５Ｂの一側端（図３において左側端）に対向して、長手方向がＹ軸に平行に設けられ、その両端で枠体１４０ａ、１４０ｂの一端（図３において左端）にそれぞれ接続される。枠体１４０ｄは、第１振動板１３５Ａ及び第２振動板１３５Ｂの他側端（図３において右側端）に対向して、長手方向がＹ軸に平行に設けられ、その両端で枠体１４０ａ、１４０ｂの他端（図３において右端）にそれぞれ接続される。 In the present embodiment, the holding portion 140 includes prismatic frame bodies 140a to 140d that are integrally formed. The frame 140a is provided so as to face the open end of the first diaphragm 135A and the longitudinal direction thereof is parallel to the X axis. The frame 140b is provided so as to face the open end of the second diaphragm 135B and the longitudinal direction thereof is parallel to the X axis. The frame 140c is provided so as to face one side end (the left end in FIG. 3) of the first vibrating plate 135A and the second vibrating plate 135B, and the longitudinal direction thereof is parallel to the Y axis. Each of them is connected to one end (the left end in FIG. 3) of 140b. The frame 140d faces the other end (the right end in FIG. 3) of the first vibrating plate 135A and the second vibrating plate 135B, the longitudinal direction of which is parallel to the Y-axis, and both ends of the frame 140d, It is connected to the other end (the right end in FIG. 3) of 140b.
　保持腕１１１及び保持腕１１２は、それぞれ、保持部１４０の内側に設けられる。保持腕１１１は、長手方向がＸ軸に平行になるように設けられている。保持腕１１１，１１２は、振動部１２０と保持部１４０とを接続する。より詳細には、保持腕１１１は、一端（図３において右端）が振動部１２０の連結部１３５Ｃに接続され、他端が（図３において左端）枠体１４０ｃに接続されている。保持腕１１２は、長手方向がＸ軸に平行になるように設けられている。保持腕１１２は、一端（図３において左端）が振動部１２０の連結部１３５Ｃに接続され、他端が（図３において右端）枠体１４０ｄに接続されている。図３に示すように、保持腕１１１及び保持腕１１２は、振動部１２０のＸ軸方向の中心線に沿ってＹＺ平面に平行に規定される仮想平面Ｐに対して略面対称に形成される。 The holding arm 111 and the holding arm 112 are provided inside the holding unit 140, respectively. The holding arm 111 is provided such that its longitudinal direction is parallel to the X axis. The holding arms 111 and 112 connect the vibrating unit 120 and the holding unit 140. More specifically, the holding arm 111 has one end (the right end in FIG. 3) connected to the connecting portion 135C of the vibrating portion 120 and the other end (the left end in FIG. 3) connected to the frame body 140c. The holding arm 112 is provided so that its longitudinal direction is parallel to the X axis. One end (the left end in FIG. 3) of the holding arm 112 is connected to the connecting portion 135C of the vibrating part 120, and the other end (the right end in FIG. 3) is connected to the frame body 140d. As shown in FIG. 3, the holding arm 111 and the holding arm 112 are formed substantially symmetrically with respect to an imaginary plane P defined parallel to the YZ plane along the center line of the vibrating section 120 in the X-axis direction. ..
　保持腕１１１及び保持腕１１２のＸ軸方向の幅は、例えば１０μｍ程度である。保持腕１１１及び保持腕１１２は、振動部１２０におけるＹ軸方向の中心線に沿って、振動部１２０を保持部１４０に接続する。 The width of the holding arm 111 and the holding arm 112 in the X-axis direction is, for example, about 10 μm. The holding arm 111 and the holding arm 112 connect the vibrating section 120 to the holding section 140 along the center line of the vibrating section 120 in the Y-axis direction.
　図３に示す平面視において、保持腕１１１及び保持腕１１２を通る直線、例えばＸ軸に平行な線を軸として捉えると、第１振動板１３５Ａは、保持腕１１１，１１２に関して一方側、つまり、Ｙ軸正方向側に配置されている。一方、第２振動板１３５Ｂは、保持腕１１１，１１２に関して他方側、つまり、Ｙ軸負方向側に配置されている。 In the plan view shown in FIG. 3, when a straight line passing through the holding arms 111 and 112, for example, a line parallel to the X axis is taken as an axis, the first diaphragm 135A has one side with respect to the holding arms 111 and 112, that is, It is arranged on the Y axis positive direction side. On the other hand, the second diaphragm 135B is arranged on the other side with respect to the holding arms 111 and 112, that is, on the Y axis negative direction side.
　なお、図３では、保持腕１１１及び保持腕１１２が仮想平面Ｐに対して略面対称に形成される例を示したが、これに限定されるものではない。例えば、保持腕は、一本だけでもよく、この場合、振動部１２０は、保持腕に片持ち支持されて、保持部１４０に保持される。 Although FIG. 3 shows an example in which the holding arm 111 and the holding arm 112 are formed substantially symmetrically with respect to the virtual plane P, the present invention is not limited to this. For example, the number of holding arms may be one, and in this case, the vibrating section 120 is cantilevered by the holding arm and held by the holding section 140.
　このように、振動部１２０が、面外屈曲振動を主振動としてそれぞれが逆位相で振動する第１振動板１３５Ａ及び第２振動板１３５Ｂを含み、平面視したときに、第１振動板１３５Ａが保持腕１１１，１１２に関して一方側に配置され、第２振動板１３５Ｂが保持腕１１１，１１２に関して他方側に配置される。これにより、振動部１２０において、保持腕１１１，１１２との接続部分が固定端となり、保持腕１１１，１１２に関して一方側に配置される第１振動板１３５Ａと保持腕１１１，１１２に関して他方側に配置される第２振動板１３５Ｂとが自由端として振動するので、従来の共振子と比較して、振動領域の面積を拡大することができる。従って、静電容量の低下を抑制することができ、等価直列容量を小さくすることができる。 As described above, the vibrating section 120 includes the first diaphragm 135A and the second diaphragm 135B that vibrate in the opposite phases with the out-of-plane bending vibration as the main vibration, and the first diaphragm 135A is The holding arms 111 and 112 are arranged on one side, and the second diaphragm 135B is arranged on the other side with respect to the holding arms 111 and 112. Accordingly, in the vibrating section 120, the connecting portion with the holding arms 111 and 112 serves as a fixed end, and the first vibrating plate 135A arranged on one side with respect to the holding arms 111 and 112 and the other side with respect to the holding arms 111 and 112. Since the second vibrating plate 135B is vibrated as a free end, the area of the vibrating region can be expanded as compared with the conventional resonator. Therefore, it is possible to suppress a decrease in electrostatic capacity and reduce an equivalent series capacity.
　次に、図４から図６を参照しつつ、本発明の一実施形態に係る共振子１０の積層構造について説明する。図４は、図３に示したＩＶ－ＩＶ線に沿った断面の構成を概略的に示す断面図である。図５は、共振子１０に電圧を印加する構成を示す断面図である。図６は、図３に示した共振子１０の振動態様を模式的に示す斜視図である。 Next, the laminated structure of the resonator 10 according to the embodiment of the present invention will be described with reference to FIGS. 4 to 6. FIG. 4 is a sectional view schematically showing a configuration of a section taken along line IV-IV shown in FIG. FIG. 5 is a sectional view showing a configuration for applying a voltage to the resonator 10. FIG. 6 is a perspective view schematically showing a vibration mode of the resonator 10 shown in FIG.
　共振子１０における、振動部１２０、保持部１４０、及び保持腕１１１，１１２は、同一プロセスで一体的に形成される。図４に示すように、共振子１０における振動部１２０は、基板の一例であるシリコン（Ｓｉ）基板（以下、「Ｓｉ基板」という）Ｆ２の上に、Ｓｉ基板Ｆ２を覆うように圧電薄膜Ｆ３が形成され、さらに圧電薄膜Ｆ３の上には、金属層Ｅ２が積層されている。そして、金属層Ｅ２の上には、金属層Ｅ２を覆うように圧電薄膜Ｆ３が積層されており、さらに、圧電薄膜Ｆ３の上には、金属層Ｅ１が積層されている。なお、本実施形態の圧電薄膜Ｆ３、金属層Ｅ２及び金属層Ｅ１は、本発明の「圧電層」の一例に相当する。 The vibrating part 120, the holding part 140, and the holding arms 111 and 112 in the resonator 10 are integrally formed in the same process. As shown in FIG. 4, the vibrating section 120 of the resonator 10 includes a piezoelectric thin film F3 on a silicon (Si) substrate (hereinafter referred to as “Si substrate”) F2, which is an example of a substrate, so as to cover the Si substrate F2. And the metal layer E2 is laminated on the piezoelectric thin film F3. The piezoelectric thin film F3 is laminated on the metal layer E2 so as to cover the metal layer E2, and the metal layer E1 is further laminated on the piezoelectric thin film F3. The piezoelectric thin film F3, the metal layer E2, and the metal layer E1 of the present embodiment correspond to an example of the “piezoelectric layer” of the present invention.
　このように、振動部１２０の基板の材料が、シリコン（Ｓｉ）であることにより、振動部１２０の機械的強度を高めることができる。 As described above, since the material of the substrate of the vibrating section 120 is silicon (Si), the mechanical strength of the vibrating section 120 can be increased.
　Ｓｉ基板Ｆ２は、例えば、厚さ６μｍ程度の縮退したｎ型シリコン（Ｓｉ）半導体から形成されていてもよい。縮退シリコン（Ｓｉ）は、ｎ型ドーパントとしてリン（Ｐ）やヒ素（Ａｓ）、アンチモン（Ｓｂ）等を含むことができる。Ｓｉ基板Ｆ２に用いられる縮退シリコン（Ｓｉ）の抵抗値は、例えば１６ｍΩ・ｃｍ未満であり、より好ましくは１．２ｍΩ・ｃｍ以下である。 The Si substrate F2 may be formed of, for example, a degenerate n-type silicon (Si) semiconductor having a thickness of about 6 μm. The degenerate silicon (Si) can contain phosphorus (P), arsenic (As), antimony (Sb), or the like as an n-type dopant. The resistance value of the degenerate silicon (Si) used for the Si substrate F2 is, for example, less than 16 mΩ·cm, and more preferably 1.2 mΩ·cm or less.
　このように、振動部１２０の基板の材料が、縮退シリコン（Ｓｉ）であることにより、周波数温度特性を向上させることができる。 As described above, since the material of the substrate of the vibrating section 120 is degenerate silicon (Si), the frequency temperature characteristic can be improved.
　また、Ｓｉ基板Ｆ２の上面と圧電薄膜Ｆ３との間には、絶縁層Ｆ２１が配置されている。絶縁層Ｆ２１は、例えば二酸化ケイ素（ＳｉＯ２）等の絶縁膜を用いて形成される。絶縁層Ｆ２１の厚さは、例えば０．５μｍ程度である。 Further, an insulating layer F21 is arranged between the upper surface of the Si substrate F2 and the piezoelectric thin film F3. The insulating layer F21 is formed using an insulating film such as silicon dioxide (SiO 2 ). The insulating layer F21 has a thickness of, for example, about 0.5 μm.
　さらに、Ｓｉ基板Ｆ２の下面、つまり、Ｓｉ基板Ｆ２を間に介在させて絶縁層Ｆ２１の反対側に、補正層Ｆ２２が配置されている。補正層Ｆ２２は、例えば二酸化ケイ素（例えばＳｉＯ２）を用いて形成される。 Further, the correction layer F22 is arranged on the lower surface of the Si substrate F2, that is, on the opposite side of the insulating layer F21 with the Si substrate F2 interposed therebetween. The correction layer F22 is formed by using, for example, silicon dioxide (eg, SiO 2 ).
　本実施形態において、補正層Ｆ２２とは、当該補正層Ｆ２２をＳｉ基板Ｆ２に形成しない場合と比べて、Ｓｉ基板Ｆ２に補正層を形成したときの振動部１２０における周波数の温度係数、つまり、温度当たりの変化率を、少なくとも常温近傍において低減する機能を持つ層をいう。振動部１２０が補正層Ｆ２２を含むことにより、例えば、Ｓｉ基板Ｆ２と金属層Ｅ１、Ｅ２と圧電薄膜Ｆ３と補正層Ｆ２２とによる積層構造体の共振周波数において、温度に伴う変化を低減することができ、温度特性を向上させることができる。 In the present embodiment, the correction layer F22 is a temperature coefficient of the frequency in the vibrating section 120 when the correction layer is formed on the Si substrate F2, that is, the temperature, as compared with the case where the correction layer F22 is not formed on the Si substrate F2. A layer having a function of reducing the change rate per hit at least near room temperature. Since the vibrating section 120 includes the correction layer F22, for example, the resonance frequency of the laminated structure including the Si substrate F2, the metal layers E1 and E2, the piezoelectric thin film F3, and the correction layer F22 can be reduced with a change in temperature. It is possible to improve temperature characteristics.
　金属層Ｅ１、Ｅ２は、例えば厚さ０．１μｍ以上０．２μｍ以下程度であり、成膜後に、エッチング等により所望の形状にパターニングされる。金属層Ｅ１、Ｅ２は、結晶構造が体心立法構造である金属が用いられている。具体的には、金属層Ｅ１、Ｅ２は、Ｍｏ（モリブデン）、タングステン（Ｗ）等を用いて形成される。 The metal layers E1 and E2 have a thickness of, for example, 0.1 μm or more and 0.2 μm or less, and are patterned into a desired shape by etching or the like after the film formation. The metal layers E1 and E2 are made of a metal whose crystal structure is a body-centered cubic structure. Specifically, the metal layers E1 and E2 are formed using Mo (molybdenum), tungsten (W), or the like.
　金属層Ｅ１は、例えば振動部１２０上においては、上部電極としての役割を果たすように形成される。また、金属層Ｅ１は、保持腕１１１，１１２及び保持部１４０上においては、共振子１０の外部に設けられた交流電源に上部電極を接続するための配線としての役割を果たすように形成される。 The metal layer E1 is formed, for example, on the vibrating portion 120 so as to serve as an upper electrode. In addition, the metal layer E1 is formed on the holding arms 111 and 112 and the holding portion 140 so as to function as a wiring for connecting the upper electrode to an AC power supply provided outside the resonator 10. ..
　一方、金属層Ｅ２は、振動部１２０上においては、下部電極としての役割を果たすように形成される。また、金属層Ｅ２は、保持腕１１０や保持部１４０上においては、共振子１０の外部に設けられた回路に下部電極を接続するための配線としての役割を果たすように形成される。 On the other hand, the metal layer E2 is formed on the vibrating portion 120 so as to serve as a lower electrode. Further, the metal layer E2 is formed on the holding arm 110 and the holding portion 140 so as to serve as a wiring for connecting the lower electrode to a circuit provided outside the resonator 10.
　なお、Ｓｉ基板Ｆ２として、例えば低抵抗値である縮退シリコン基板を用いることで、Ｓｉ基板Ｆ２自体が下部電極の役割を兼ねることが可能であり、金属層Ｅ２を省略することができる。 Note that, by using, for example, a degenerate silicon substrate having a low resistance value as the Si substrate F2, the Si substrate F2 itself can also serve as the lower electrode, and the metal layer E2 can be omitted.
　圧電薄膜Ｆ３は、印加された電圧を振動に変換する圧電体の薄膜である。圧電薄膜Ｆ３は、結晶構造がウルツ鉱型六方晶構造を持つ材質から形成されており、例えば、窒化アルミニウム（ＡｌＮ）、窒化スカンジウムアルミニウム（ＳｃＡｌＮ）、酸化亜鉛（ＺｎＯ）、窒化ガリウム（ＧａＮ）、窒化インジウム（ＩｎＮ）等の窒化物や酸化物を主成分とすることができる。なお、窒化スカンジウムアルミニウムは、窒化アルミニウムにおけるアルミニウムの一部がスカンジウムに置換されたものであり、スカンジウムの代わりにマグネシウム（Ｍｇ）及びニオブ（Ｎｂ）やマグネシウム（Ｍｇ）及びジルコニウム（Ｚｒ）等の２元素で置換されていてもよい。また、圧電薄膜Ｆ３は、例えば１μｍの厚さを有するが、０．２μｍから２μｍ程度の厚さを用いることも可能である。 The piezoelectric thin film F3 is a piezoelectric thin film that converts an applied voltage into vibration. The piezoelectric thin film F3 is formed of a material having a wurtzite type hexagonal crystal structure, and includes, for example, aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), A nitride or oxide such as indium nitride (InN) can be the main component. Note that scandium aluminum nitride is obtained by replacing a part of aluminum in aluminum nitride with scandium, and instead of scandium, magnesium (Mg) and niobium (Nb) or magnesium (Mg) and zirconium (Zr) and the like 2 are used. It may be substituted with an element. Further, the piezoelectric thin film F3 has a thickness of, for example, 1 μm, but it is also possible to use a thickness of about 0.2 μm to 2 μm.
　共振装置１は、図示しない一組の外部電極を備えており、当該外部電極から金属層Ｅ１、Ｅ２に電圧が印加され、金属層Ｅ１、Ｅ２によって圧電薄膜Ｆ３に印加される電界に応じて、圧電薄膜Ｆ３はＸＹ平面の面内方向すなわちＹ軸方向に伸縮する。この圧電薄膜Ｆ３の伸縮によって、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、下蓋２０及び上蓋３０の内面に向かってその自由端を変位させ、面外の屈曲振動モードで振動する。 The resonance device 1 includes a set of external electrodes (not shown), a voltage is applied from the external electrodes to the metal layers E1 and E2, and in response to an electric field applied to the piezoelectric thin film F3 by the metal layers E1 and E2, The piezoelectric thin film F3 expands and contracts in the in-plane direction of the XY plane, that is, in the Y-axis direction. Due to the expansion and contraction of the piezoelectric thin film F3, the first diaphragm 135A and the second diaphragm 135B displace their free ends toward the inner surfaces of the lower lid 20 and the upper lid 30, respectively, and vibrate in the out-of-plane bending vibration mode. ..
　図５に示すように、本実施形態では、第１振動板１３５Ａに印加される電界の位相と、第２振動板１３５Ｂに印加される電界の位相とが互いに逆位相になるように設定されている。この結果、図６に示すように、第１振動板１３５Ａと第２振動板１３５Ｂとが互いに逆方向に変位する。例えば、第１振動板１３５Ａが上蓋３０の内面に向かってＺ軸正方向側に自由端を変位すると、第２振動板１３５Ｂは下蓋２０の内面に向かってＺ軸負方向側に自由端を変位する。なお、図６において、色の薄い領域は振動による変位が小さい領域であることを示し、色の濃い領域は振動による変位が大きい領域であることを示している。 As shown in FIG. 5, in the present embodiment, the phase of the electric field applied to the first diaphragm 135A and the phase of the electric field applied to the second diaphragm 135B are set to be opposite to each other. There is. As a result, as shown in FIG. 6, the first diaphragm 135A and the second diaphragm 135B are displaced in opposite directions. For example, when the first diaphragm 135A displaces the free end toward the Z axis positive direction toward the inner surface of the upper lid 30, the second diaphragm 135B moves the free end toward the Z axis negative direction toward the inner surface of the lower lid 20. Displace. In FIG. 6, a light-colored area indicates that the displacement due to vibration is small, and a dark-colored area indicates that the displacement due to vibration is large.
　また、連結部１３５Ｃは、第１振動板１３５Ａ及び第２振動板１３５Ｂの固定端であるから、振動部１２０におけるノードとなる。さらに、連結部１３５Ｃにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂは保持腕１１１，１１２によって保持部１４０に保持されるので、第１振動板１３５Ａ及び第２振動板１３５Ｂの振動時に、振動の保持ロス又はアンカーロスを低減することが可能となる。このように、第１振動板１３５Ａ及び第２振動板１３５Ｂが、連結部１３５Ｃと保持部１４０とを接続する保持腕１１１，１１２によって、保持部１４０に保持されることにより、振動部１２０がＹ軸方向の中央で保持されるので、振動の保持ロス又はアンカーロスによるＱ値の低下を抑制することができる。 Further, since the connecting portion 135C is a fixed end of the first diaphragm 135A and the second diaphragm 135B, it serves as a node in the vibrating portion 120. Further, in the connecting portion 135C, since the first vibrating plate 135A and the second vibrating plate 135B are held by the holding portion 140 by the holding arms 111 and 112, when the first vibrating plate 135A and the second vibrating plate 135B vibrate, they vibrate. It is possible to reduce the retention loss or anchor loss of the. In this way, the first vibrating plate 135A and the second vibrating plate 135B are held by the holding portion 140 by the holding arms 111 and 112 that connect the connecting portion 135C and the holding portion 140, so that the vibrating portion 120 becomes Y. Since it is held at the center in the axial direction, it is possible to suppress a decrease in Q value due to vibration holding loss or anchor loss.
　図３及び図４に示した、第１振動板１３５Ａ及び第２振動板１３５ＢのそれぞれのＹ軸方向の長さＬは、面外屈曲振動における波長λの１／２倍に設定されることが好ましい。これにより、静電容量の低下を抑制する振動部１２０を容易に実現することができる。 The length L in the Y-axis direction of each of the first diaphragm 135A and the second diaphragm 135B shown in FIGS. 3 and 4 may be set to 1/2 times the wavelength λ in the out-of-plane bending vibration. preferable. This makes it possible to easily realize the vibrating section 120 that suppresses a decrease in electrostatic capacitance.
　次に、図７及び図８を参照しつつ、絶縁層Ｆ２１の機能について説明する。図７は、図４に示した絶縁層Ｆ２１を含まない仮想的な振動部における周波数と熱弾性損失に依存するＱ値との関係を示すグラフである。図８は、図４に示した絶縁層Ｆ２１を含む振動部１２０における周波数と熱弾性損失に依存するＱ値との関係を示すグラフである。なお、図７及び図８に示すグラフでは、図４に示したＳｉ基板Ｆ２の厚さを、５μｍ、１０μｍ、２０μｍ、及び３０μｍにしたときの値を、それぞれプロットしている。 Next, the function of the insulating layer F21 will be described with reference to FIGS. 7 and 8. FIG. 7 is a graph showing the relationship between the frequency and the Q value depending on the thermoelastic loss in the virtual vibration part that does not include the insulating layer F21 shown in FIG. FIG. 8 is a graph showing the relationship between the frequency and the Q value depending on the thermoelastic loss in the vibrating section 120 including the insulating layer F21 shown in FIG. In the graphs shown in FIGS. 7 and 8, the values when the thickness of the Si substrate F2 shown in FIG. 4 is 5 μm, 10 μm, 20 μm, and 30 μm are plotted, respectively.
　ここで、共振子１０における共振振動のＱ値（以下、単に「Ｑ値」という）は、共振周波数が１０ＭＨｚ以下の範囲において、熱弾性損失（ＴＥＤ：Ｔｈｅｒｍｏｅｌａｓｔｉｃ　Ｄａｍｐｉｎｇ）が主要因又はボトルネックであることが分かっている。そのため、振動部１２０は、この熱弾性損失を低減させる構造を備えることが望ましい。 Here, the Q value of the resonance vibration in the resonator 10 (hereinafter, simply referred to as “Q value”) is mainly due to thermoelastic loss (TED: Thermoelastic Damping) in the resonance frequency range of 10 MHz or less. I know that. Therefore, it is desirable that the vibrating section 120 has a structure that reduces this thermoelastic loss.
　図７及び図８に示すように、どちらのグラフもある周波数で変曲点を有している。変曲点よりも低い周波数の範囲では、Ｓｉ基板Ｆ２の厚さが小さいほど、Ｑ値が高くなっている。すなわち、この周波数範囲では、熱伝達時間が短いほど、Ｑ値が高くなることを意味している。一方、変曲点よりも高い周波数の範囲では、Ｓｉ基板Ｆ２の厚さが大きいほど、Ｑ値が高くなっている。すなわち、この周波数範囲では、熱伝達時間が長いほど、Ｑ値が高くなることを意味している。このように、変曲点よりも高い周波数範囲では、熱伝達時間を長くした方がＱ値を高くすることができ、共振子１０の共振周波数である１ＭＨｚ（＝１０３ｋＨＺ）以上１０ＭＨｚ（＝１０４ｋＨＺ）以下の範囲で特に顕著である。 As shown in FIGS. 7 and 8, both graphs have an inflection point at a certain frequency. In the frequency range lower than the inflection point, the smaller the thickness of the Si substrate F2, the higher the Q value. That is, in this frequency range, the shorter the heat transfer time, the higher the Q value. On the other hand, in the frequency range higher than the inflection point, the larger the thickness of the Si substrate F2, the higher the Q value. That is, in this frequency range, the longer the heat transfer time, the higher the Q value. As described above, in the frequency range higher than the inflection point, the Q value can be increased by increasing the heat transfer time, and the resonance frequency of the resonator 10 is 1 MHz (=10 3 kHZ) or more and 10 MHz (= It is particularly remarkable in the range of 10 4 kHZ) or less.
　また、図７に示す、図４に示した絶縁層Ｆ２１を含まない仮想的な振動部の場合のグラフと、図８に示す、図４に示した絶縁層Ｆ２１を含む振動部１２０の場合のグラフとを比較すると、絶縁層Ｆ２１を含む振動部１２０の方がＱ値を向上させており、１ＭＨｚ（＝１０３ｋＨＺ）以上の範囲で特に顕著であることが分かる。 In addition, FIG. 7 shows a graph of a virtual vibrating portion not including the insulating layer F21 shown in FIG. 4 and FIG. 8 shows a vibrating portion 120 including the insulating layer F21 shown in FIG. Comparing with the graph, it can be seen that the vibrating portion 120 including the insulating layer F21 has a higher Q value and is particularly remarkable in the range of 1 MHz (=10 3 kHZ) or more.
　ここで、絶縁層Ｆ２１の主成分である二酸化ケイ素（ＳｉＯ２）は、熱伝導率が１．４［Ｗ／（ｍ／Ｋ）］であり、他の材料と比較して、熱伝導率が極めて低いことが知られている。また、図４に示したように、絶縁層Ｆ２１はＳｉ基板Ｆ２の上面、言い換えれば、振動部１２０の厚さ方向の中央付近に配置されている。この場合、絶縁層Ｆ２１を他の位置に配置する場合と比較して、熱伝導時間が長くなる。このように、二酸化ケイ素（ＳｉＯ２）を主成分とする絶縁層Ｆ２１をＳｉ基板Ｆ２と圧電薄膜Ｆ３との間に配置することにより、Ｑ値の低下を抑制することができ、熱弾性損失（ＴＥＤ）がＱ値の主要因又はボトルネックとなる１ＭＨｚ以上１０ＭＨｚ以下の範囲において特に顕著である。 Here, silicon dioxide (SiO 2 ) which is the main component of the insulating layer F21 has a thermal conductivity of 1.4 [W/(m/K)], which is higher than that of other materials. It is known to be extremely low. Further, as shown in FIG. 4, the insulating layer F21 is arranged on the upper surface of the Si substrate F2, in other words, near the center of the vibrating portion 120 in the thickness direction. In this case, the heat conduction time becomes longer than in the case where the insulating layer F21 is arranged at another position. As described above, by disposing the insulating layer F21 containing silicon dioxide (SiO 2 ) as a main component between the Si substrate F2 and the piezoelectric thin film F3, it is possible to suppress the decrease in Q value and to reduce the thermoelastic loss ( It is particularly remarkable in the range of 1 MHz or more and 10 MHz or less where TED) becomes a main factor or bottleneck of the Q value.
　次に、図９を参照しつつ、第１振動板１３５Ａ及び第２振動板１３５Ｂのアスペクト比Ｗ／Ｌについて説明する。図９は、アスペクト比Ｗ／Ｌと電気機械結合係数ｋとの関係を示すグラフである。なお、図９に示すグラフでは、第１振動板１３５Ａ及び第２振動板１３５ＢのＹ軸方向の長さＬを、０．１０ｍｍ、０．１３ｍｍ、０．１６ｍｍ、及び０．１８ｍｍにしたときの値を、それぞれプロットしている。また、図９に示す振動部１２０Ａ～１２０Ｇにおいて、色の薄い領域は振動による変位が小さい領域であることを示し、色の濃い領域は振動による変位が大きい領域であることを示している。 Next, the aspect ratio W/L of the first diaphragm 135A and the second diaphragm 135B will be described with reference to FIG. FIG. 9 is a graph showing the relationship between the aspect ratio W/L and the electromechanical coupling coefficient k. In the graph shown in FIG. 9, when the length L of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is 0.10 mm, 0.13 mm, 0.16 mm, and 0.18 mm. The values are plotted respectively. Further, in the vibrating sections 120A to 120G shown in FIG. 9, a light-colored area indicates a small displacement due to vibration, and a dark-colored area indicates a large displacement due to vibration.
　図９に示すように、アスペクト比Ｗ／Ｌが１．０、３．０、及び５．０において、周期的に電気機械結合係数ｋが低下することが確認できる。例えば、アスペクト比Ｗ／Ｌが１．０のときの振動状態を示す振動部１２０Ｂを見ると、長さＬ方向の面外屈曲振動のみならず、幅Ｗ方向にも面外屈曲振動が発生していることが分かる。長さＬと幅Ｗとが等しいい場合、長さＬ方向の面外屈曲振動の周波数と幅Ｗ方向の面外屈曲振動の周波数とが一致するので、これらが結合することで振動モードが変わってしまい、電気機械結合係数ｋが低下するものと考えられる。同様に、アスペクト比Ｗ／Ｌが３．０又は５．０の場合、長さＬ方向の面外屈曲振動の周波数と幅Ｗ方向の面外屈曲振動の３倍波又は５倍波の周波数とが一致して結合することで、電気機械結合係数ｋが低下するものと考えられる。 As shown in FIG. 9, it can be confirmed that the electromechanical coupling coefficient k periodically decreases when the aspect ratio W/L is 1.0, 3.0, and 5.0. For example, looking at the vibrating portion 120B showing the vibrating state when the aspect ratio W/L is 1.0, not only the out-of-plane bending vibration in the length L direction but also the out-of-plane bending vibration in the width W direction occurs. I understand that. When the length L and the width W are equal, the frequency of the out-of-plane bending vibration in the direction of the length L and the frequency of the out-of-plane bending vibration in the direction of the width W are the same. It is considered that the electromechanical coupling coefficient k decreases due to the change. Similarly, when the aspect ratio W/L is 3.0 or 5.0, the frequency of the out-of-plane bending vibration in the length L direction and the frequency of the third or fifth harmonic of the out-of-plane bending vibration in the width W direction. It is considered that the electromechanical coupling coefficient k decreases due to the coincidence and coupling.
　本実施形態において、アスペクト比Ｗ／Ｌは、２ｎ－１（ｎは自然数）の値を避けて、０．１≦Ｗ／Ｌ≦０．９、又は２ｎ－０．８≦Ｗ／Ｌ≦２ｎ＋０．９の範囲に設定されている。これにより、不要な振動モードとの結合を防止することができる。従って、電気機械結合係数ｋの低下を抑制することができる。 In this embodiment, the aspect ratio W/L is 0.1≦W/L≦0.9, or 2n−0.8≦W/L≦2n+0, avoiding a value of 2n−1 (n is a natural number). It is set in the range of 0.9. This can prevent coupling with an unnecessary vibration mode. Therefore, the reduction of the electromechanical coupling coefficient k can be suppressed.
　次に、図１０を参照しつつ、第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬに対する金属層Ｅ１の長さＬｅの比Ｌｅ／Ｌについて説明する。図１０は、比Ｌｅ／Ｌと電気機械結合係数ｋとの関係を示すグラフである。なお、図１０に示すグラフでは、アスペクト比Ｗ／Ｌを、０．６及び４．０にしたときの値を、それぞれプロットしている。また、図１０に示すグラフは、振動部１２０において、長さＬが０．１０ｍｍ、Ｓｉ基板Ｆ２の厚さが１０μｍ、絶縁層Ｆ２１の厚さが０．５μｍ、金属層Ｅ１，Ｅ２の厚さが０．２μｍ、圧電薄膜Ｆ３が０．８μｍであるときの値である。 Next, the ratio Le/L of the length Le of the metal layer E1 to the length L of the first diaphragm 135A and the second diaphragm 135B will be described with reference to FIG. FIG. 10 is a graph showing the relationship between the ratio Le/L and the electromechanical coupling coefficient k. In the graph shown in FIG. 10, the values when the aspect ratio W/L is set to 0.6 and 4.0 are plotted. The graph shown in FIG. 10 shows that in the vibrating section 120, the length L is 0.10 mm, the Si substrate F2 has a thickness of 10 μm, the insulating layer F21 has a thickness of 0.5 μm, and the metal layers E1 and E2 have thicknesses. Is 0.2 μm and the piezoelectric thin film F3 is 0.8 μm.
　図１０に示すように、比Ｌｅ／Ｌが０．３以上、さらに好ましくは０．５以上の範囲において、電気機械結合係数ｋの値が相対的に高くなっていることが分かる。特に、比Ｌｅ／Ｌが０．６の周辺において、電気機械結合係数ｋが最大となっている。本実施形態において、比Ｌｅ／Ｌは、０．３≦Ｌｅ／Ｌ＜１．０の範囲に設定されている。これにより、電気機械結合係数ｋを高めることができる。 As shown in FIG. 10, it can be seen that the value of the electromechanical coupling coefficient k is relatively high when the ratio Le/L is 0.3 or more, more preferably 0.5 or more. In particular, the electromechanical coupling coefficient k is maximized around the ratio Le/L of 0.6. In the present embodiment, the ratio Le/L is set in the range of 0.3≦Le/L<1.0. Thereby, the electromechanical coupling coefficient k can be increased.
　本実施形態では、図３及び図４に示した第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬが、面外屈曲振動における波長λの１／２倍に設定される例を示したが、これに限定されるものではない。例えば、第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬは、面外屈曲振動における波長λのｍ／２（ｍは２以上の正の整数）倍に設定されてもよい。 In the present embodiment, an example is shown in which the length L of the first diaphragm 135A and the second diaphragm 135B shown in FIGS. 3 and 4 is set to 1/2 times the wavelength λ in the out-of-plane bending vibration. However, it is not limited to this. For example, the length L of the first diaphragm 135A and the second diaphragm 135B may be set to m/2 (m is a positive integer of 2 or more) times the wavelength λ in the out-of-plane bending vibration.
　＜第１変形例＞
　図１１及び図１２は、図６に示した振動部１２０の変形例の振動態様を模式的に示す斜視図である。なお、図１１に示す振動部１２０Ｈと図１２に示す振動部１２０Ｉとにおいて、色の薄い領域は振動による変位が小さい領域であることを示し、色の濃い領域は振動による変位が大きい領域であることを示している。 <First Modification>
11 and 12 are perspective views schematically showing a vibration mode of a modified example of the vibrating section 120 shown in FIG. In the vibrating section 120H shown in FIG. 11 and the vibrating section 120I shown in FIG. 12, a light-colored area indicates a small displacement due to vibration, and a dark-colored area indicates a large displacement due to vibration. It is shown that.
　図１１に示す振動部１２０Ｈにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬは、面外屈曲振動における波長λの３／２倍に設定されている。この場合、振動部１２０Ｈの第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、面外屈曲振動の３倍波で駆動される。 In the vibrating section 120H shown in FIG. 11, the length L of the first vibrating plate 135A and the second vibrating plate 135B is set to 3/2 times the wavelength λ in the out-of-plane bending vibration. In this case, the first vibrating plate 135A and the second vibrating plate 135B of the vibrating section 120H are each driven by the third harmonic of the out-of-plane bending vibration.
　また、第１振動板１３５Ａ及び第２振動板１３５Ｂは、面外屈曲振動の奇数倍波で駆動される場合に限定されるものではなく、面外屈曲振動の偶数倍波で駆動されてもよい。 Further, the first diaphragm 135A and the second diaphragm 135B are not limited to being driven by the odd harmonics of the out-of-plane bending vibration, and may be driven by the even harmonics of the out-of-plane bending vibration. ..
　図１２に示す振動部１２０Ｉにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬは、面外屈曲振動における波長λと同じ値に設定されている。この場合、振動部１２０Ｉの第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、面外屈曲振動の２倍波で駆動される。 In the vibrating section 120I shown in FIG. 12, the length L of the first vibrating plate 135A and the second vibrating plate 135B is set to the same value as the wavelength λ in the out-of-plane bending vibration. In this case, the first vibrating plate 135A and the second vibrating plate 135B of the vibrating section 120I are each driven by the second harmonic of the out-of-plane bending vibration.
　このように、第１振動板１３５Ａ及び第２振動板１３５ＢのそれぞれのＹ軸方向の長さＬを、面外屈曲振動における波長λのｍ／２（ｍは２以上の正の整数）倍に設定することにより、振動領域の面積をさらに拡大することができる。 In this way, the length L of each of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is m/2 (m is a positive integer of 2 or more) times the wavelength λ in the out-of-plane bending vibration. By setting it, the area of the vibration region can be further expanded.
　本実施形態では、図３において、第１振動板１３５Ａ及び第２振動板１３５Ｂが、平面視において矩形の形状を有する例を示したが、これに限定されるものではない。例えば、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、矩形以外の形状を有していてもよい。また、振動部１２０が２つの第１振動板１３５Ａ及び第２振動板１３５Ｂを含む例を示したが、これに場合に限定されるものではない。例えば、振動部１２０は、第１振動板１３５Ａ及び第２振動板１３５Ｂに加え、他の振動板を含んでいてもよい。 In the present embodiment, an example in which the first diaphragm 135A and the second diaphragm 135B have a rectangular shape in plan view is shown in FIG. 3, but the present invention is not limited to this. For example, the first diaphragm 135A and the second diaphragm 135B may each have a shape other than a rectangle. Further, the example in which the vibrating section 120 includes the two first vibrating plates 135A and the second vibrating plate 135B is shown, but the present invention is not limited to this. For example, the vibrating section 120 may include another vibrating plate in addition to the first vibrating plate 135A and the second vibrating plate 135B.
　＜第２変形例＞
　図１３から図１７は、図３に示した振動部１２０の変形例を示す平面図である。なお、図１３から図１７に示すＡ－Ａ’線に沿った断面は、図４に示した断面と同様であるため、図示及びその構成についての説明を省略する。 <Second Modification>
13 to 17 are plan views showing modified examples of the vibrating section 120 shown in FIG. Note that the cross section taken along the line AA′ shown in FIGS. 13 to 17 is the same as the cross section shown in FIG. 4, and therefore illustration and description of the configuration thereof will be omitted.
　図１３に示す振動部１２０Ｊにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、略台形状の形状を有している。具体的には、第１振動板１３５Ａは、連結部１３５Ｃの辺と比較して、枠体１４０ａに対向する辺が短くなっており、自由端の幅が狭くなっている。同様に、第２振動板１３５Ｂは、連結部１３５Ｃの辺と比較して、枠体１４０ｂに対向する辺が短くなっており、自由端の幅が狭くなっている。また、図１４に示す振動部１２０Ｋにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、略三角形状の形状を有している。具体的には、第１振動板１３５Ａは、連結部１３５Ｃの辺に対して、枠体１４０ａに対向する側が角部となっており、自由端の幅が狭くなっている。同様に、第２振動板１３５Ｂは、連結部１３５Ｃの辺に対して、枠体１４０ｂに対向する側が角部となっており、自由端の幅が狭くなっている。一方、図１５に示す振動部１２０Ｌにおいて、第１振動板１３５Ａ及び第２振動板１３５Ｂは、それぞれ、略逆台形状の形状を有している。具体的には、第１振動板１３５Ａは、連結部１３５Ｃの辺と比較して、枠体１４０ａに対向する辺が長くなっており、自由端の幅が広くなっている。同様に、第２振動板１３５Ｂは、連結部１３５Ｃの辺と比較して、枠体１４０ｂに対向する辺が長くなっており、自由端の幅が広くなっている。 In the vibrating section 120J shown in FIG. 13, the first vibrating plate 135A and the second vibrating plate 135B each have a substantially trapezoidal shape. Specifically, in the first diaphragm 135A, the side facing the frame 140a is shorter and the width of the free end is narrower than the side of the connecting portion 135C. Similarly, in the second diaphragm 135B, the side facing the frame 140b is shorter and the width of the free end is narrower than the side of the connecting portion 135C. Further, in the vibrating section 120K shown in FIG. 14, each of the first vibrating plate 135A and the second vibrating plate 135B has a substantially triangular shape. Specifically, in the first diaphragm 135A, the side facing the frame 140a is a corner with respect to the side of the connecting portion 135C, and the width of the free end is narrow. Similarly, in the second vibrating plate 135B, the side facing the frame 140b is a corner with respect to the side of the connecting portion 135C, and the width of the free end is narrow. On the other hand, in the vibrating section 120L shown in FIG. 15, each of the first vibrating plate 135A and the second vibrating plate 135B has a substantially inverted trapezoidal shape. Specifically, in the first diaphragm 135A, the side facing the frame 140a is longer and the width of the free end is wider than the side of the connecting portion 135C. Similarly, in the second diaphragm 135B, the side facing the frame 140b is longer and the width of the free end is wider than the side of the connecting portion 135C.
　図１６に示す振動部１２０Ｍは、第１振動板１３５Ａ及び第２振動板１３５Ｂに加え、矩形平板状の形状を有する第３振動板１３５Ｄを含む。第１振動板１３５Ａと第３振動板１３５Ｄとは、Ｘ軸方向に所定幅離間して配置されている。第１振動板１３５ＡのＹ軸負方向側の端部及び第３振動板１３５ＤのＹ軸負方向側の端部は、第２振動板１３５ＢのＹ軸正方向側の端部と連結しており、連結部１３５Ｃを形成している。第１振動板１３５Ａ及び第２振動板１３５Ｂは、図１６に示す直交座標系におけるＸＹ平面内で、面外屈曲振動モードを主振動としてそれぞれが逆位相で振動し、第３振動板１３５Ｄ及び第２振動板１３５Ｂは、図１６に示す直交座標系におけるＸＹ平面内で、面外屈曲振動モードを主振動としてそれぞれが逆位相で振動する。 The vibrating section 120M shown in FIG. 16 includes a first vibrating plate 135A and a second vibrating plate 135B, and a third vibrating plate 135D having a rectangular flat plate shape. The first vibrating plate 135A and the third vibrating plate 135D are arranged with a predetermined width apart in the X-axis direction. The end of the first diaphragm 135A on the negative Y-axis side and the end of the third diaphragm 135D on the negative Y-axis side are connected to the end of the second diaphragm 135B on the positive Y-axis side. , And a connecting portion 135C is formed. The first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG. 16, and the third diaphragm 135D and the third diaphragm 135D The two vibrating plates 135B vibrate in opposite phases in the XY plane in the orthogonal coordinate system shown in FIG. 16 with the out-of-plane bending vibration mode as the main vibration.
　図１７に示す振動部１２０Ｎは、第１振動板１３５Ａ及び第２振動板１３５Ｂに加え、矩形平板状の形状を有する第３振動板１３５Ｄ及び第４振動板１３５Ｅを含む。第１振動板１３５Ａと第３振動板１３５Ｄとは、Ｘ軸方向に所定幅離間して配置されている。同様に、第２振動板１３５Ｂと第４振動板１３５Ｅとは、Ｘ軸方向に所定幅離間して配置されている。第１振動板１３５ＡのＹ軸負方向側の端部は、第２振動板１３５ＢのＹ軸正方向側の端部と連結しており、連結部１３５Ｃを形成している。同様に、第３振動板１３５ＤのＹ軸負方向側の端部は、第４振動板１３５ＥのＹ軸正方向側の端部と連結しており、連結部１３５Ｆを形成している。振動部１２０Ｍは接続腕１３６をさらに含み、接続腕１３６は、第１振動板１３５Ａ及び第２振動板１３５Ｂと、第３振動板１３５Ｄ及び第４振動板１３５Ｅとを接続している。第１振動板１３５Ａ及び第２振動板１３５Ｂは、図１６に示す直交座標系におけるＸＹ平面内で、面外屈曲振動モードを主振動としてそれぞれが逆位相で振動し、第３振動板１３５Ｄ及び第４振動板１３５Ｅは、図１６に示す直交座標系におけるＸＹ平面内で、面外屈曲振動モードを主振動としてそれぞれが逆位相で振動する。 The vibrating section 120N shown in FIG. 17 includes, in addition to the first vibrating plate 135A and the second vibrating plate 135B, a third vibrating plate 135D and a fourth vibrating plate 135E having a rectangular flat plate shape. The first vibrating plate 135A and the third vibrating plate 135D are arranged with a predetermined width apart in the X-axis direction. Similarly, the second vibrating plate 135B and the fourth vibrating plate 135E are spaced apart by a predetermined width in the X-axis direction. An end of the first diaphragm 135A on the Y-axis negative direction side is connected to an end of the second diaphragm 135B on the Y-axis positive direction side to form a connecting portion 135C. Similarly, the end of the third diaphragm 135D on the Y-axis negative direction side is connected to the end of the fourth diaphragm 135E on the Y-axis positive direction side to form a connecting portion 135F. The vibrating section 120M further includes a connecting arm 136, and the connecting arm 136 connects the first vibrating plate 135A and the second vibrating plate 135B to the third vibrating plate 135D and the fourth vibrating plate 135E. The first diaphragm 135A and the second diaphragm 135B vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG. 16, and the third diaphragm 135D and the third diaphragm 135D The four vibrating plates 135E vibrate in opposite phases with the out-of-plane bending vibration mode as the main vibration in the XY plane in the Cartesian coordinate system shown in FIG.
　本実施形態では、図３において、保持腕１１１，１１２が、平面視において矩形の形状を有する例を示したが、これに限定されるものではない。振動部１２０と保持部１４０とを接続するものであれば、他の形態であってもよい。 In the present embodiment, an example in which the holding arms 111 and 112 have a rectangular shape in plan view is shown in FIG. 3, but the present invention is not limited to this. Other forms may be used as long as they connect the vibrating part 120 and the holding part 140.
　＜第３変形例＞
　図１８及び図１９は、図３に示した共振子１０の変形例を示す平面図である。なお、図１８及び図１９に示すＢ－Ｂ’線に沿った断面は、図４に示した断面と同様であるため、図示及びその構成についての説明を省略する。 <Third Modification>
18 and 19 are plan views showing modified examples of the resonator 10 shown in FIG. Note that the cross section taken along the line BB′ shown in FIGS. 18 and 19 is the same as the cross section shown in FIG. 4, and therefore illustration and description of the configuration thereof will be omitted.
　図１８に示す共振子１０Ａは、図３に示した保持腕１１１，１１２に代えて、保持ユニット１１１Ａ，１１２Ａを備える。保持ユニット１１１Ａは振動緩衝部４ａを含み、保持ユニット１１２Ａは振動緩衝部４ｂを含んでいる。振動緩衝部４ａ、４ｂは、それぞれ、Ｙ軸正方向側及びＹ軸負方向側に突出している。振動緩衝部４ａ、４ｂは、それぞれ、腕１１１ａによって振動部１２０に接続され、腕１１１ｂによって保持部１４０に接続されている。このように、保持ユニット１１１Ａ，１１２Ａが振動緩衝部４ａ、４ｂを含むことにより、振動部１２０から伝搬してきた面外屈曲振動の高調波の振動を効率的に閉じ込めることができる。保持ユニット１１１Ａは振動緩衝部４ａを含み、保持ユニット１１２Ａは振動緩衝部４ｂを含んでいる。 The resonator 10A shown in FIG. 18 includes holding units 111A and 112A instead of the holding arms 111 and 112 shown in FIG. The holding unit 111A includes the vibration damping portion 4a, and the holding unit 112A includes the vibration damping portion 4b. The vibration damping portions 4a and 4b respectively project to the Y-axis positive direction side and the Y-axis negative direction side. The vibration buffers 4a and 4b are respectively connected to the vibration part 120 by the arm 111a and connected to the holding part 140 by the arm 111b. As described above, since the holding units 111A and 112A include the vibration damping portions 4a and 4b, it is possible to efficiently trap the harmonic vibration of the out-of-plane bending vibration that has propagated from the vibrating portion 120. The holding unit 111A includes the vibration damping portion 4a, and the holding unit 112A includes the vibration damping portion 4b.
　図１９に示す共振子１０Ｂは、図３に示した保持腕１１１，１１２に代えて、保持ユニット１１１Ｂ，１１２Ｂを備える。保持ユニット１１１Ｂはノード生成部１３０Ａを含み、保持ユニット１１２Ｂはノード生成部１３０Ｂを含んでいる。ノード生成部１３０Ａ，１３０Ｂは、それぞれ、腕１１１ａによって振動部１２０に接続され、腕１１１ｂによって保持部１４０に接続されている。また、ノード生成部１３０Ａは、振動部１２０の長辺と対向する辺１３１ａを有し、当該辺１３１ａにおいて腕１１１ａに接続されている。同様に、ノード生成部１３０Ｂは、振動部１２０の長辺と対向する辺１３１ｂを有し、当該辺１３１ｂにおいて腕１１１ａに接続されている。 The resonator 10B shown in FIG. 19 includes holding units 111B and 112B instead of the holding arms 111 and 112 shown in FIG. The holding unit 111B includes a node generation unit 130A, and the holding unit 112B includes a node generation unit 130B. Each of the node generation units 130A and 130B is connected to the vibrating unit 120 by an arm 111a and connected to the holding unit 140 by an arm 111b. Further, the node generation unit 130A has a side 131a facing the long side of the vibrating unit 120, and is connected to the arm 111a at the side 131a. Similarly, the node generation unit 130B has a side 131b facing the long side of the vibrating unit 120, and is connected to the arm 111a at the side 131b.
　ノード生成部１３０Ａ，１３０Ｂは、それぞれ、Ｘ軸方向に沿った幅が、腕１１１ａから腕１１１ｂへと向かうにつれて狭まる形状を有する。また、ノード生成部１３０Ａ，１３０Ｂは、それぞれ、辺１３１ａの垂直二等分線に対して線対称の形状を有する。ノード生成部１３０Ａ，１３０Ｂは、それぞれ、Ｙ軸方向に沿った幅が最大となる箇所を、Ｘ軸方向における中心よりも腕１１１ａ側に有している。本実施形態においては、ノード生成部１３０ＡのＹ軸方向に沿った幅は、辺１３１ａにおいて最大であり、腕１１１ａから腕１１１ｂへと向かうにつれて、徐々に狭くなり、ノード生成部１３０Ａの頂点と腕１１１ｂとの接続箇所において最も狭くなる。ノード生成部１３０Ｂについても同様である。なお、ノード生成部１３０Ａ，１３０ＢのＹ軸方向に沿った幅は、それぞれ、連続的に狭まる必要はなく、例えば、段階的に狭まったり、一部に広がる部分を有していたりしても、全体として徐々に狭まっていればよい。また、ノード生成部１３０Ａ，１３０Ｂの周縁は、それぞれ、滑らかな形状に限らず、凹凸を有してもよい。 Each of the node generation units 130A and 130B has a shape in which the width along the X-axis direction becomes narrower from the arm 111a toward the arm 111b. In addition, the node generation units 130A and 130B each have a line-symmetrical shape with respect to the vertical bisector of the side 131a. Each of the node generation units 130A and 130B has a portion having the maximum width along the Y-axis direction on the arm 111a side with respect to the center in the X-axis direction. In the present embodiment, the width of the node generation unit 130A along the Y-axis direction is the maximum on the side 131a and gradually narrows from the arm 111a to the arm 111b, and the apex and the arm of the node generation unit 130A. It becomes the narrowest at the connection point with 111b. The same applies to the node generation unit 130B. The widths of the node generators 130A and 130B along the Y-axis direction do not need to be continuously narrowed, and for example, even if the widths are gradually narrowed or partially widened, It should be gradually narrowed as a whole. Further, the peripheral edges of the node generating units 130A and 130B are not limited to the smooth shape, and may have irregularities.
　本実施形態において、ノード生成部１３０Ａは、例えば辺１３１ａを直径とする半径３０μｍ程度の半円の形状をしている。この場合、ノード生成部１３０Ａの円弧を形成する円の中心は、辺１３１ａの中心に位置する。なお、ノード生成部１３０Ａの円弧を形成する円の中心は、腕１１１ｂの中心に位置してもよい。また、辺１３１ａは、直線形状に限らず円弧形状でもよい。この場合、腕１１１ａは、辺１３１ａの頂点と接続される。さらにこの場合、辺１３１ａの円弧を形成する円の中心は、腕１１１ａ側に位置してもよいし、腕１１１ｂ側に位置してもよい。辺１３１ａの長さは、腕１１１ａのＹ軸方向に沿った幅よりも大きく、振動部１２０の長辺よりも小さいことが好ましい。なお、ノード生成部１３０Ｂについても同様であるため、その説明を省略する。 In the present embodiment, the node generation unit 130A has, for example, a semicircular shape having a diameter of the side 131a and a radius of about 30 μm. In this case, the center of the circle forming the arc of the node generation unit 130A is located at the center of the side 131a. The center of the circle forming the arc of the node generation unit 130A may be located at the center of the arm 111b. Further, the side 131a is not limited to a straight line shape, but may be an arc shape. In this case, the arm 111a is connected to the apex of the side 131a. Further, in this case, the center of the circle forming the arc of the side 131a may be located on the arm 111a side or the arm 111b side. The length of the side 131a is preferably larger than the width of the arm 111a along the Y-axis direction and smaller than the long side of the vibrating section 120. Since the same applies to the node generation unit 130B, the description thereof will be omitted.
　本実施形態における保持ユニット１１１Ｂのノード生成部１３０Ａと保持ユニット１１２Ｂのノード生成部１３０Ｂとは、それぞれ、Ｘ軸方向に沿った幅が、腕１１１ａから腕１１１ｂへ向かうにつれて徐々に狭まっている構造である。このため、振動部１２０から伝搬される振動の伝搬状態が変化した場合であっても、ノード生成部１３０Ａ，１３０Ｂには、それぞれ、振動による変位が大きい部位に隣接して変位が小さい部位が形成される。これによって、ノード生成部１３０Ａ，１３０Ｂは、それぞれ、振動部１２０から漏えいした振動に対し、変位部位を調整して、ノード生成部１３０Ａ，１３０Ｂ上に振動のノードを形成することができる。ノード生成部１３０Ａ，１３０Ｂは、それぞれ、この形成されたノードにおいて、腕１１１ａに接続されることによって、振動部１２０から保持部１４０への振動の伝搬を抑制することができる。この結果、共振子１０Ｂのアンカーロスを低減させることができ、Ｑ値を向上させることができる。 The node generation unit 130A of the holding unit 111B and the node generation unit 130B of the holding unit 112B in the present embodiment each have a structure in which the width along the X-axis direction gradually narrows from the arm 111a toward the arm 111b. is there. Therefore, even when the propagation state of the vibration propagating from the vibrating unit 120 changes, the node generating units 130A and 130B each have a small displacement region adjacent to a large displacement region due to the vibration. To be done. Accordingly, the node generation units 130A and 130B can adjust the displacement parts with respect to the vibration leaked from the vibration unit 120 and form the vibration nodes on the node generation units 130A and 130B, respectively. The node generation units 130A and 130B can suppress the propagation of vibration from the vibration unit 120 to the holding unit 140 by being connected to the arms 111a at the formed nodes. As a result, the anchor loss of the resonator 10B can be reduced and the Q value can be improved.
　［第２実施形態］
　次に、図２０及び図２１を参照しつつ、本発明の第２実施形態に係る共振装置について説明する。なお、以下の実施形態において、第１実施形態と同一又は類似の構成について同一又は類似の符号を付し、第１実施形態と異なる点について説明する。また、図示しない構成については、第１実施形態と同一であるものとする。さらに、同様の構成による同様の作用効果については、逐次言及しない。 [Second Embodiment]
Next, a resonance device according to the second embodiment of the present invention will be described with reference to FIGS. 20 and 21. In the following embodiments, the same or similar reference numerals will be given to the same or similar configurations as the first embodiment, and the points different from the first embodiment will be described. The configuration not shown is the same as that of the first embodiment. Furthermore, the same operation effect by the same structure will not be referred to one by one.
　まず、図２０及び図２１を参照しつつ、本発明の第２実施形態に係る共振子１０における第１振動板１３５Ａ及び第２振動板１３５Ｂのアスペクト比Ｗ／Ｌについて説明する。図２０は、アスペクト比Ｗ／Ｌと電気機械結合係数ｋとの関係を示すグラフである。図２１は、アスペクト比Ｗ／Ｌと保持ユニットの変位量との関係を示すグラフである。なお、図２０及び図２１に示すグラフでは、第１振動板１３５Ａ及び第２振動板１３５ＢのＹ軸方向の長さＬを、０．１０ｍｍ、０．１３ｍｍ、０．１６ｍｍ、及び０．１８ｍｍにしたときの値を、それぞれプロットしている。また、図２０及び図２１に示す振動部１２０Ｐ～１２０Ｗにおいて、色の薄い領域は振動による変位が小さい領域であることを示し、色の濃い領域は振動による変位が大きい領域であることを示している。さらに、図２１の縦軸は、保持ユニットと保持部の接続面における変位量を面積積分した値を示しており、単位はｍｍ３である。この値は振動漏れを表す指標である。つまり、保持部ユニットと保持部の接続面の変位が大きいほど、保持部へ振動が伝搬し、Ｑ値が低下する。 First, the aspect ratio W/L of the first diaphragm 135A and the second diaphragm 135B in the resonator 10 according to the second embodiment of the present invention will be described with reference to FIGS. 20 and 21. FIG. 20 is a graph showing the relationship between the aspect ratio W/L and the electromechanical coupling coefficient k. FIG. 21 is a graph showing the relationship between the aspect ratio W/L and the displacement amount of the holding unit. In the graphs shown in FIGS. 20 and 21, the length L of the first diaphragm 135A and the second diaphragm 135B in the Y-axis direction is 0.10 mm, 0.13 mm, 0.16 mm, and 0.18 mm. The values at each time are plotted. Further, in the vibrating sections 120P to 120W shown in FIGS. 20 and 21, a light-colored area indicates that the displacement due to vibration is small, and a dark-colored area indicates that the displacement due to vibration is large. There is. Further, the vertical axis of FIG. 21 shows a value obtained by performing area integration on the displacement amount at the connecting surface between the holding unit and the holding portion, and the unit is mm 3 . This value is an index indicating vibration leakage. That is, the greater the displacement of the connecting surface between the holding unit and the holding unit, the more the vibration propagates to the holding unit and the Q value decreases.
　図２０及び図２１に示すように、振動部１２０Ｓは、電気機械結合係数ｋが高いものの、保持ユニットの変位量が大きいので、振動漏れが大きくなっている。振動部１２０Ｓは、第１振動板１３５Ａ及び第２振動板１３５Ｂの長さＬ方向に屈曲振動しており、この振動モードをＬＢモードという。一方、ＷＢモードは、第１振動板１３５Ａ及び第２振動板１３５Ｂの幅Ｗ方向に屈曲振動する振動モードであり、振動の閉じ込め性が高い。 As shown in FIGS. 20 and 21, the vibrating section 120S has a high electromechanical coupling coefficient k, but the displacement of the holding unit is large, so vibration leakage is large. The vibrating portion 120S flexurally vibrates in the length L direction of the first vibrating plate 135A and the second vibrating plate 135B, and this vibration mode is referred to as the LB mode. On the other hand, the WB mode is a vibration mode in which bending vibration occurs in the width W direction of the first diaphragm 135A and the second diaphragm 135B, and the vibration confinement is high.
　振動部１２０Ｒ，１２０Ｔ，１２０Ｖは、それぞれ、ＬＢモードとＷＢノードとの結合振動であるＣＢモードで振動している。振動部１２０Ｒはアスペクト比Ｗ／Ｌが１．４であり、振動部１２０Ｔはアスペクト比Ｗ／Ｌが３．２であり、振動部１２０Ｖはアスペクト比Ｗ／Ｌが４．９である。図２０及び図２１から明らかなように、振動部１２０Ｒ，１２０Ｔ，１２０Ｖは、それぞれ、電気機械結合係数ｋが高く、かつ、保持ユニットの変位量が小さいので、高い電気機械結合係数ｋ及び振動閉じ込め性を両立している。そのため、振動部１２０Ｒ，１２０Ｔ，１２０Ｖでは、高いＱ値を期待することができる。 The vibrating sections 120R, 120T, and 120V each vibrate in the CB mode, which is the combined vibration of the LB mode and the WB node. The vibrating portion 120R has an aspect ratio W/L of 1.4, the vibrating portion 120T has an aspect ratio W/L of 3.2, and the vibrating portion 120V has an aspect ratio W/L of 4.9. As apparent from FIGS. 20 and 21, the vibrating portions 120R, 120T, and 120V have high electromechanical coupling coefficient k and small displacement amount of the holding unit, respectively, so that high electromechanical coupling coefficient k and vibration confinement are achieved. It has both sex. Therefore, a high Q value can be expected in the vibrating sections 120R, 120T, 120V.
　以上、本発明の例示的な実施形態について説明した。本発明の一実施形態に係る共振子は、振動部が、面外屈曲振動を主振動としてそれぞれが逆位相で振動する第１振動板及び第２振動板を含み、振動部の主面を平面視したときに、第１振動板が保持腕に関して一方側に配置され、第２振動板が保持腕に関して他方側に配置される。これにより、振動部において、保持腕との接続部分が固定端となり、保持腕に関して一方側に配置される第１振動板と保持腕に関して他方側に配置される第２振動板とが自由端として振動するので、従来の共振子と比較して、振動領域の面積を拡大することができる。従って、静電容量の低下を抑制することができ、等価直列容量を小さくすることができる。 The exemplary embodiments of the present invention have been described above. In the resonator according to the embodiment of the present invention, the vibrating portion includes a first vibrating plate and a second vibrating plate that vibrate in opposite phases with the out-of-plane bending vibration as a main vibration. When viewed, the first diaphragm is arranged on one side with respect to the holding arm, and the second diaphragm is arranged on the other side with respect to the holding arm. As a result, in the vibrating portion, the connecting portion with the holding arm serves as a fixed end, and the first diaphragm arranged on one side of the holding arm and the second diaphragm arranged on the other side of the holding arm serve as free ends. Since it vibrates, the area of the vibrating region can be expanded as compared with the conventional resonator. Therefore, it is possible to suppress a decrease in electrostatic capacity and reduce an equivalent series capacity.
　また、前述した共振子において、連結部が第１振動板と第２振動板とを連結し、保持腕が連結部と保持部とを接続する。これにより、振動部がＹ軸方向の中央で保持されるので、振動の保持ロス又はアンカーロスによるＱ値の低下を抑制することができる。 Also, in the resonator described above, the connecting portion connects the first diaphragm and the second diaphragm, and the holding arm connects the connecting portion and the holding portion. With this, the vibrating portion is held at the center in the Y-axis direction, so that it is possible to suppress a decrease in Q value due to vibration holding loss or anchor loss.
　また、前述した共振子において、第１振動板及び第２振動板のそれぞれのＹ軸方向の長さＬに対するＸ軸方向の幅Ｗの比Ｗ／Ｌが、０．１≦Ｗ／Ｌ≦０．９、又は２ｎ－０．８≦Ｗ／Ｌ≦２ｎ＋０．９の範囲に設定される。これにより、不要な振動モードとの結合を防止することができる。従って、電気機械結合係数ｋの低下を抑制することができる。 In the above-described resonator, the ratio W/L of the width W in the X-axis direction to the length L in the Y-axis direction of each of the first diaphragm and the second diaphragm is 0.1≦W/L≦0. .9, or 2n−0.8≦W/L≦2n+0.9. This can prevent coupling with an unnecessary vibration mode. Therefore, the reduction of the electromechanical coupling coefficient k can be suppressed.
　また、前述した共振子において、第１振動板及び第２振動板のそれぞれのＹ軸方向の長さＬに対する金属層のＹ軸方向の長さＬｅの比Ｌｅ／Ｌが、０．３≦Ｌｅ／Ｌ＜１．０の範囲に設定される。これにより、電気機械結合係数ｋを高めることができる。 In the resonator described above, the ratio Le/L of the length Le in the Y-axis direction of the metal layer to the length L in the Y-axis direction of each of the first diaphragm and the second diaphragm is 0.3≦Le. /L<1.0 is set. Thereby, the electromechanical coupling coefficient k can be increased.
　また、前述した共振子において、第１振動板及び第２振動板のそれぞれのＹ軸方向の長さＬが、面外屈曲振動における波長の１／２倍に設定される。これにより、静電容量の低下を抑制する振動部を容易に実現することができる。 In the resonator described above, the length L of each of the first diaphragm and the second diaphragm in the Y-axis direction is set to 1/2 the wavelength of the out-of-plane bending vibration. With this, it is possible to easily realize the vibrating unit that suppresses the decrease in electrostatic capacitance.
　また、前述した共振子において、第１振動板及び第２振動板のそれぞれのＹ軸方向の長さＬが、面外屈曲振動における波長のｍ／２（ｍは２以上の正の整数）倍に設定されることにより、振動領域の面積をさらに拡大することができる。 In the resonator described above, the length L of each of the first diaphragm and the second diaphragm in the Y-axis direction is m/2 (m is a positive integer of 2 or more) times the wavelength in the out-of-plane bending vibration. By setting to, the area of the vibration region can be further expanded.
　また、前述した共振子において、二酸化ケイ素（ＳｉＯ２）を主成分とする絶縁層をＳｉ基板と圧電薄膜との間に配置することにより、Ｑ値の低下を抑制することができ、熱弾性損失（ＴＥＤ）がＱ値の主要因又はボトルネックとなる１ＭＨｚ以上１０ＭＨｚ以下の範囲において特に顕著である。 Further, in the above-described resonator, by disposing the insulating layer containing silicon dioxide (SiO 2 ) as a main component between the Si substrate and the piezoelectric thin film, it is possible to suppress the Q value from decreasing and to reduce the thermoelastic loss. It is particularly remarkable in the range of 1 MHz or more and 10 MHz or less where (TED) is the main factor or bottleneck of the Q value.
　また、前述した共振子において、振動部の基板の材料が、シリコン（Ｓｉ）である。これにより、振動部の機械的強度を高めることができる。 Also, in the resonator described above, the material of the substrate of the vibration part is silicon (Si). Thereby, the mechanical strength of the vibrating portion can be increased.
　また、前述した共振子において、振動部１２０の基板の材料が、縮退シリコン（Ｓｉ）である。これにより、周波数温度特性を向上させることができる。 In addition, in the resonator described above, the material of the substrate of the vibrating portion 120 is degenerate silicon (Si). As a result, the frequency temperature characteristic can be improved.
　また、前述した共振子において、補正層が、Ｓｉ基板を間に介在させて絶縁層の反対側に配置される。これにより、例えば、Ｓｉ基板と金属層と圧電薄膜と補正層とによる積層構造体の共振周波数において、温度に伴う変化を低減することができ、温度特性を向上させることができる。 Also, in the resonator described above, the correction layer is arranged on the opposite side of the insulating layer with the Si substrate interposed therebetween. Thereby, for example, it is possible to reduce a change with temperature in the resonance frequency of the laminated structure including the Si substrate, the metal layer, the piezoelectric thin film, and the correction layer, and improve the temperature characteristic.
　また、前述した共振子において、振動部が圧電薄膜を含む。これにより、面外屈曲振動する振動部を容易に実現することができる。 Also, in the resonator described above, the vibrating portion includes a piezoelectric thin film. This makes it possible to easily realize a vibrating portion that causes out-of-plane bending vibration.
　また、前述した共振子において、振動部が他の金属層をさらに含む。これにより、面外屈曲振動する振動部をさらに容易に実現することができる。 Also, in the resonator described above, the vibrating portion further includes another metal layer. This makes it possible to more easily realize a vibrating portion that causes out-of-plane bending vibration.
　本発明の一実施形態に係る共振装置は、前述した共振子と、共振子の振動空間を形成する下蓋及び上蓋と、外部電極とを備える。これにより、静電容量の低下を抑制する共振装置を容易に実現することができる。 A resonance device according to an embodiment of the present invention includes the resonator described above, a lower lid and an upper lid that form a vibration space of the resonator, and an external electrode. As a result, it is possible to easily realize a resonance device that suppresses a decrease in capacitance.
　なお、以上説明した各実施形態は、本発明の理解を容易にするためのものであり、本発明を限定して解釈するためのものではない。本発明は、その趣旨を逸脱することなく、変更／改良され得るとともに、本発明にはその等価物も含まれる。すなわち、各実施形態及び／又は各変形例に当業者が適宜設計変更を加えたものも、本発明の特徴を備えている限り、本発明の範囲に包含される。例えば、各実施形態及び／又は各変形例が備える各要素及びその配置、材料、条件、形状、サイズなどは、例示したものに限定されるわけではなく適宜変更することができる。また、各実施形態及び各変形例は例示であり、異なる実施形態及び／又は変形例で示した構成の部分的な置換又は組み合わせが可能であることは言うまでもなく、これらも本発明の特徴を含む限り本発明の範囲に包含される。 The above-described embodiments are for the purpose of facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. The present invention can be modified/improved without departing from the spirit thereof and includes the equivalents thereof. That is, a person skilled in the art appropriately modified the design of each embodiment and/or each modification is also included in the scope of the present invention as long as the characteristics of the present invention are provided. For example, each element included in each embodiment and/or each modified example and the arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed. Further, it is needless to say that each embodiment and each modification are mere examples, and it is possible to partially replace or combine the configurations shown in different embodiments and/or modifications, and these also include the features of the present invention. As long as it falls within the scope of the present invention.
　１　　　　　　　　　　　　　　　　　　　共振装置
　１０，１０Ａ，１０Ｂ　　　　　　　　　　共振子
　２０　　　　　　　　　　　　　　　　　　下蓋
　３０　　　　　　　　　　　　　　　　　　上蓋
　１１１，１１２　　　　　　　　　　　　　保持腕
　１１１Ａ，１１１Ｂ，１１２Ａ，１１２Ｂ　保持腕
　１２０，１２０Ａ～Ｎ，１２０Ｐ～Ｗ　　　振動部
　１３５Ａ　　　　　　　　　　　　　　　　第１振動板
　１３５Ｂ　　　　　　　　　　　　　　　　第２振動板
　１３５Ｃ　　　　　　　　　　　　　　　　連結部
　１３５Ｄ　　　　　　　　　　　　　　　　第３振動板
　１３５Ｅ　　　　　　　　　　　　　　　　第４振動板
　１３５Ｆ　　　　　　　　　　　　　　　　連結部
　１４０　　　　　　　　　　　　　　　　　保持部
　１４０ａ～ｄ　　　　　　　　　　　　　　枠体
　Ｅ１，Ｅ２　　　　　　　　　　　　　　　金属層
　Ｆ２　　　　　　　　　　　　　　　　　　Ｓｉ基板
　Ｆ２１　　　　　　　　　　　　　　　　　絶縁層
　Ｆ２２　　　　　　　　　　　　　　　　　補正層
　Ｆ３　　　　　　　　　　　　　　　　　　圧電薄膜 DESCRIPTION OF SYMBOLS 1 Resonance device 10, 10A, 10B Resonator 20 Lower lid 30 Upper lid 111, 112 Holding arm 111A, 111B, 112A, 112B Holding arm 120, 120A-N, 120P-W Vibrating part 135A 1st diaphragm 135B 2nd diaphragm 135C Connecting part 135D Third vibrating plate 135E Fourth vibrating plate 135F Connecting part 140 Holding part 140a-d Frame body E1, E2 Metal layer F2 Si substrate F21 Insulating layer F22 Correction layer F3 Piezoelectric thin film

Claims (13)

  1. 　面外屈曲振動を主振動としてそれぞれが逆位相で振動する第１振動部及び第２振動部を含む振動部と、
    　前記振動部の少なくとも一部を囲むように形成される保持部と、
    　前記振動部と前記保持部とを接続する保持ユニットと、を備え、
    　前記振動部の主面を平面視したときに、前記第１振動部が前記保持ユニットに関して一方側に配置され、前記第２振動部が前記保持ユニットに関して他方側に配置される、
    　共振子。     A vibrating section including a first vibrating section and a second vibrating section, each of which vibrates in an opposite phase with the out-of-plane bending vibration as a main vibration;
    A holding portion formed so as to surround at least a part of the vibrating portion,
    A holding unit that connects the vibrating unit and the holding unit,
    The first vibrating portion is arranged on one side with respect to the holding unit, and the second vibrating portion is arranged on the other side with respect to the holding unit when the main surface of the vibrating portion is viewed in a plan view.
    Resonator.
  2. 　振動部は、前記第１振動部と前記第２振動部とを連結する連結部をさらに含み、
    　保持ユニットは、前記連結部と前記保持部とを接続する、
    　請求項１に記載の共振子。     The vibrating part further includes a connecting part that connects the first vibrating part and the second vibrating part,
    The holding unit connects the connecting portion and the holding portion,
    The resonator according to claim 1.
  3. 　前記第１振動部及び前記第２振動部のそれぞれは、第１方向の長さＬと第２方向の幅Ｗとを有し、
    　前記長さＬに対する前記幅Ｗの比Ｗ／Ｌが、
    　０．１≦Ｗ／Ｌ≦０．９、又は２ｎ－０．８≦Ｗ／Ｌ≦２ｎ＋０．９（ｎは正の整数）
    　の範囲に設定される、
    　請求項１又は２に記載の共振子。     Each of the first vibrating portion and the second vibrating portion has a length L in a first direction and a width W in a second direction,
    The ratio W/L of the width W to the length L is
    0.1≦W/L≦0.9, or 2n−0.8≦W/L≦2n+0.9 (n is a positive integer)
    Set to the range of
    The resonator according to claim 1 or 2.
  4. 　前記第１振動部及び前記第２振動部のぞれぞれは、電極を含み、
    　前記長さＬに対する前記電極の前記第１方向の長さＬｅの比Ｌｅ／Ｌが、
    　０．３≦Ｌｅ／Ｌ＜１．０
    　の範囲に設定される、
    　請求項３に記載の共振子。     Each of the first vibrating portion and the second vibrating portion includes an electrode,
    The ratio Le/L of the length Le of the electrode in the first direction to the length L is
    0.3≦Le/L<1.0
    Set to the range of
    The resonator according to claim 3.
  5. 　前記長さＬは、前記面外屈曲振動における波長の１／２倍に設定される、
    　請求項３又は４に記載の共振子。     The length L is set to 1/2 times the wavelength of the out-of-plane bending vibration,
    The resonator according to claim 3 or 4.
  6. 　前記長さＬは、前記面外屈曲振動における波長のｍ／２（ｍは２以上の正の整数）倍に設定される、
    　請求項３又は４に記載の共振子。     The length L is set to m/2 (m is a positive integer of 2 or more) times the wavelength in the out-of-plane bending vibration.
    The resonator according to claim 3 or 4.
  7. 　前記振動部は、基板と圧電層と二酸化シリコンを主成分とする絶縁層とを含み、
    　前記絶縁層は、前記基板と前記圧電層との間に配置される、
    　請求項１から６のいずれか一項に記載の共振子。     The vibrating portion includes a substrate, a piezoelectric layer, and an insulating layer containing silicon dioxide as a main component,
    The insulating layer is disposed between the substrate and the piezoelectric layer,
    The resonator according to any one of claims 1 to 6.
  8. 　前記基板の材料は、シリコンである、
    　請求項７に記載の共振子。     The material of the substrate is silicon,
    The resonator according to claim 7.
  9. 　前記基板の材料は、縮退シリコンである、
    　請求項７に記載の共振子。     The material of the substrate is degenerate silicon,
    The resonator according to claim 7.
  10. 　前記振動部は、補正層をさらに含み、
    　前記補正層は、前記基板を間に介在させて前記絶縁層と反対側に配置される、
    　請求項７から９のいずれか一項に記載の共振子。     The vibrating unit further includes a correction layer,
    The correction layer is arranged on the opposite side of the insulating layer with the substrate interposed therebetween.
    The resonator according to any one of claims 7 to 9.
  11. 　前記圧電層は、圧電膜を含む、
    　請求項７から１０のいずれか一項に記載の共振子。     The piezoelectric layer includes a piezoelectric film,
    The resonator according to any one of claims 7 to 10.
  12. 　前記圧電層は、他の電極をさらに含む、
    　請求項７から１１のいずれか一項に記載の共振子。     The piezoelectric layer further includes another electrode,
    The resonator according to any one of claims 7 to 11.
  13. 　請求項１から１２のいずれか一項に記載の共振子と、
    　前記共振子の振動空間を形成する蓋体と、
    　外部電極と、を備える、
    　共振装置。     A resonator according to any one of claims 1 to 12,
    A lid forming a vibration space of the resonator,
    An external electrode,
    Resonance device.
PCT/JP2020/001684 2019-01-24 2020-01-20 Resonator and resonance device WO2020153287A1 (en)

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* Cited by examiner, † Cited by third party
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JPS5689113A (en) * 1979-12-20 1981-07-20 Seiko Instr & Electronics Ltd Thin type quartz oscillator
WO2016114237A1 (en) * 2015-01-16 2016-07-21 株式会社村田製作所 Resonator
WO2016158056A1 (en) * 2015-03-31 2016-10-06 株式会社村田製作所 Resonance device
WO2017051572A1 (en) * 2015-09-21 2017-03-30 株式会社村田製作所 Resonator and resonance device
WO2017203741A1 (en) * 2016-05-26 2017-11-30 株式会社村田製作所 Resonator and resonance device
WO2018118219A1 (en) * 2016-12-22 2018-06-28 Murata Manufacturing Co., Ltd. Corner coupling resonator array
JP2018186501A (en) * 2017-04-26 2018-11-22 キヤノン株式会社 Vibrator, vibration type actuator, and electronic equipment

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5689113A (en) * 1979-12-20 1981-07-20 Seiko Instr & Electronics Ltd Thin type quartz oscillator
WO2016114237A1 (en) * 2015-01-16 2016-07-21 株式会社村田製作所 Resonator
WO2016158056A1 (en) * 2015-03-31 2016-10-06 株式会社村田製作所 Resonance device
WO2017051572A1 (en) * 2015-09-21 2017-03-30 株式会社村田製作所 Resonator and resonance device
WO2017203741A1 (en) * 2016-05-26 2017-11-30 株式会社村田製作所 Resonator and resonance device
WO2018118219A1 (en) * 2016-12-22 2018-06-28 Murata Manufacturing Co., Ltd. Corner coupling resonator array
JP2018186501A (en) * 2017-04-26 2018-11-22 キヤノン株式会社 Vibrator, vibration type actuator, and electronic equipment

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