Resonance device

Abstract

A resonance device (1) according to the present invention is provided with: a resonator (10) having: a vibration unit (110); a holding part (140) disposed on at least a portion of the periphery of the vibrating part (110); and a support arm (150) connecting the vibrating part (110) and the holding part (140). And a first substrate (20) having a first bottom plate (22) provided at a distance from the vibrating part (110) in the thickness direction, a first side wall (23) extending from the peripheral edge of the first bottom plate (22) toward the holding part (140), and a first restricting part (25) extending from the peripheral edge of the first bottom plate (22) to the holding part (140). A first metal film (M2) functioning as a getter is provided at a tip portion of the first restricting portion (25), the tip portion facing the resonator (10) in the thickness direction, such that the distance between the first restricting portion (25) and the resonator (10) in the thickness direction is smaller than the distance between the resonator (10) and the first base plate (22).

Description

Technical Field

[0001] The present invention relates to resonant devices. Background Art

[0002] Resonance devices are used in various electronic devices such as mobile communication terminals, communication base stations, and home appliances for various purposes such as timing devices, sensors, and oscillators. As one of such resonance devices, a so-called MEMS (MicroElectro Mechanical Systems) resonance device is known, which includes: a lower cover, an upper cover forming a vibration space between the lower cover, and a resonator having a vibration arm that is maintained in the vibration space so as to be able to vibrate.

[0003] For example, Patent Document 1 discloses a resonance device comprising a resonator, a lower cover, and an upper cover, wherein the lower cover has a limiting portion that is arranged at a first distance from a support arm of the resonator in a thickness direction, the limiting portion includes a step that forms a step difference between the limiting portion and the bottom surface of a recessed portion of the lower cover, and the maximum amplitude of the support arm in the thickness direction is limited to the first distance.

[0004] Patent Document 1: International Publication No. 2020-261630

[0005] However, in the resonance device described in Patent Document 1, when the support arm and the restriction portion collide, at least one of the support arm and the restriction portion may be scratched, and dust generated thereby may scatter and cause frequency fluctuation. Summary of the invention

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resonance device capable of suppressing frequency fluctuations.

[0007] A resonance device in one embodiment of the present invention comprises: a resonator having: a vibration portion; a holding portion, which is arranged at least in a portion around the vibration portion; and a support arm connecting the vibration portion and the holding portion; and a first substrate, which has a first bottom plate, a first side wall and a first limiting portion, wherein the first bottom plate is arranged to be spaced apart from the vibration portion in the thickness direction, the first side wall extends from the peripheral portion of the first bottom plate toward the holding portion, the distance between the first limiting portion and the resonator in the thickness direction is smaller than the distance between the resonator and the first bottom plate, and a first metal film functioning as a getter is provided at the front end portion of the first limiting portion which is opposite to the resonator in the thickness direction.

[0008] According to the present invention, it is possible to provide a resonance device capable of suppressing frequency fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view of the resonance device according to the first embodiment.

[0010] Figure 2 It is an exploded perspective view of the resonance device according to the first embodiment.

[0011] Figure 3 It is a top view of the interior of the resonance device according to the first embodiment.

[0012] Figure 4 It is a top view of the interior of the resonance device according to the first embodiment.

[0013] Figure 5 It is a cross-sectional view of the resonance device according to the first embodiment.

[0014] Figure 6 It is a cross-sectional view of a resonance device according to a second embodiment.

[0015] Figure 7 It is a cross-sectional view of a resonance device according to a third embodiment.

[0016] Figure 8 It is a cross-sectional view of a resonance device according to a fourth embodiment.

[0017] Fig. 9 is a cross-sectional view of a resonance device according to a fifth embodiment.

[0018] Fig.10 is a cross-sectional view of a resonance device according to a sixth embodiment.

[0019] Fig.11 It is a top view of the inside of the resonance device according to the seventh embodiment.

[0020] Fig.12 It is a top view of the interior of the resonance device according to the eighth embodiment.

[0021] Fig.13 It is a top view of the inside of the resonance device according to the ninth embodiment.

[0022] Fig.14 It is a top view of the interior of the resonance device according to the tenth embodiment. DETAILED DESCRIPTION

[0023] The following describes an embodiment of the present invention with reference to the drawings. The drawings of the present embodiment are for illustration only, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be interpreted as being limited to the embodiments.

[0024] <First embodiment>

[0025] First, refer to Figure 1 and Figure 2 A schematic structure of the resonance device 1 according to the first embodiment of the present invention will be described. Figure 1It is a perspective view of the resonance device according to the first embodiment. Figure 2 It is an exploded perspective view of the resonance device according to the first embodiment.

[0026] The following describes the various structures of the resonance device 1. In each of the drawings, in order to clarify the relationship between the drawings and to help understand the positional relationship of each component, for convenience, an orthogonal coordinate system consisting of an X-axis, a Y-axis, and a Z-axis is sometimes indicated. Directions parallel to the X-axis, the Y-axis, and the Z-axis are referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. The plane defined by the X-axis and the Y-axis is referred to as the XY plane, and the same applies to the YZ plane and the ZX plane.

[0027] The resonator device 1 includes a resonator 10, and a lower cover 20 and an upper cover 30 that face each other with the resonator 10 interposed therebetween. The lower cover 20, the resonator 10, and the upper cover 30 are stacked in this order in the Z-axis direction. Hereinafter, the Z-axis direction in which the lower cover 20, the resonator 10, and the upper cover 30 are stacked is referred to as the "thickness direction". The resonator 10 and the lower cover 20 are bonded to form a MEMS substrate 50. The upper cover 30 is bonded to the resonator 10 of the MEMS substrate 50. In other words, the upper cover 30 is bonded to the lower cover 20 via the resonator 10. The lower cover 20 and the upper cover 30 form a packaging structure that forms a vibration space inside for the resonator 10 to vibrate. One of the lower cover 20 and the upper cover 30 corresponds to an example of a first substrate, and the other of the lower cover 20 and the upper cover 30 corresponds to an example of a second substrate.

[0028] The resonator 10 is a MEMS vibration element manufactured using MEMS technology. The frequency band of the resonator 10 is, for example, 1 kHz or more and 1 MHz or less. The resonator 10 includes a vibration part 110 , a holding part 140 , and a support arm 150 .

[0029] The vibration part 110 is maintained to be able to vibrate in the vibration space provided between the lower cover 20 and the upper cover 30. The vibration part 110 extends along the XY plane when in a non-vibration state with no voltage applied, and vibrates in a bending manner in the Z-axis direction when in a vibration state with voltage applied. That is, the vibration mode of the vibration part 110 is an out-of-plane bending vibration mode. The vibration part 110 in a non-vibration state may also bend in the Z direction due to its own weight.

[0030] In addition, the vibration mode of the vibration part is not limited to the out-of-plane bending vibration mode. For example, the vibration mode of the vibration part may be an in-plane bending vibration mode or a thickness shear vibration mode.

[0031] When looking down at the XY plane (hereinafter referred to as "looking down"), the holding portion 140 is, for example, provided in a frame shape to surround the vibration portion 110. The holding portion 140 forms a vibration space of the package structure together with the lower cover 20 and the upper cover 30. In addition, the holding portion 140 only needs to be provided at least partially around the vibration portion 110, and is not limited to a frame shape.

[0032] The support arm 150 is provided between the vibration part 110 and the holding part 140 in a plan view. The support arm 150 connects the vibration part 110 and the holding part 140 .

[0033] The lower cover 20 has a bottom plate 22 and a side wall 23. The bottom plate 22 is provided at a distance from the vibration part 110 in the thickness direction. The bottom plate 22 is a plate-shaped portion having a main surface extending along the XY plane. The side wall 23 extends from the peripheral edge of the bottom plate 22 toward the upper cover 30. When viewed from above, the side wall 23 is a frame-shaped portion surrounding the vibration part 110. The side wall 23 is joined to the holding part 140 of the resonator 10. In the lower cover 20, a cavity 21 surrounded by the bottom plate 22 and the side wall 23 is formed on the side opposite to the vibration part 110 of the resonator 10. The cavity 21 is an opening portion of a rectangular parallelepiped that opens upward.

[0034] The lower cover 20 further includes a restricting portion 25. When the resonance device 1 is subjected to an impact such as a fall, the restricting portion 25 contacts a portion of the vibration portion 110 and the support arm 150 to restrict displacement of the vibration portion 110 and the support arm 150 toward the lower cover 20. The detailed structure of the restricting portion 25 will be described later.

[0035] The upper cover 30 has a bottom plate 32 and a side wall 33. The bottom plate 32 is provided at a distance from the vibration part 110 in the thickness direction. The bottom plate 32 is a plate-shaped portion having a main surface extending along the XY plane. The side wall 33 extends from the peripheral edge of the bottom plate 32 toward the lower cover 20. The side wall 33 is a frame-shaped portion surrounding the vibration part 110 when viewed from above. The side wall 33 is joined to the holding part 140 of the resonator 10. In the upper cover 30, a cavity 21 surrounded by the bottom plate 32 and the side wall 33 is formed on the side opposite to the vibration part 110 of the resonator 10. The cavity 21 is an opening portion of a rectangular parallelepiped opened upward. The cavity 21 and the cavity 31 are opposite to each other with the vibration part 110 of the resonator 10 interposed therebetween, forming a vibration space of the resonator 10.

[0036] The upper cover 30 further includes a restricting portion 35. Similar to the restricting portion 25, the restricting portion 35 restricts displacement of the vibrating portion 110 and the supporting arm 150 toward the upper cover 30 by contacting a portion of the vibrating portion 110 and the supporting arm 150. The detailed structure of the restricting portion 35 will be described later.

[0037] Two power terminals ST1 and ST2, a ground terminal GT, and a dummy terminal DT are provided on the upper surface of the upper cover 30. Hereinafter, the power terminals ST1 and ST2, the ground terminal GT, and the dummy terminal DT are collectively referred to as "external terminals". Each power terminal ST1 and ST2 is a terminal for providing a drive signal (drive voltage) to the resonator 10. Each power terminal ST1 and ST2 is electrically connected to a metal film E2 corresponding to an upper electrode of the resonator 10 described later. The ground terminal GT is a terminal for providing a reference potential to the resonator 10. The ground terminal GT is electrically connected to a metal film E1 corresponding to a lower electrode of the resonator 10 described later. The dummy terminal DT is not electrically connected to the resonator 10.

[0038] Next, refer to Figure 3 The schematic structures of the vibrating portion 110 , the holding portion 140 , and the supporting arm 150 of the resonator 10 in a plan view will be described. Figure 3 is a top view of the interior of the resonance device of the first embodiment. Figure 3 The shape of the resonator 10 when viewed from the upper cover 30 is shown. Here, the dimension along the Y-axis direction is referred to as "length", and the dimension along the X-axis direction is referred to as "width".

[0039] The resonator 10 is formed, for example, to be plane-symmetrical with respect to an imaginary plane P parallel to the YZ plane. That is, the shapes of the vibration portion 110 , the holding portion 140 , and the support arm 150 are formed to be substantially plane-symmetrical with respect to the imaginary plane P.

[0040] like Figure 3 As shown, the vibration part 110 includes an excitation part 120 composed of four vibration arms 121A, 121B, 121C, and 121D, and a base 130 connected to the excitation part 120. In addition, the number of vibration arms is not limited to four, and can be set to any number of one or more. In this embodiment, the excitation part 120 and the base 130 are formed integrally. A space is formed between the vibration part 110 and the holding part 140 at a predetermined interval.

[0041] The vibration arms 121A to 121D extend in the Y-axis direction, respectively, and are arranged in this order at a predetermined interval in the X-axis direction. The vibration arms 121A to 121D have a fixed end connected to the base 130 and an open end farthest from the base 130. The vibration arms 121A to 121D respectively have: a front end portion 122A to 122D provided on the side of the open end where the displacement of the vibration portion 110 is relatively large, and an arm portion 123A to 123D connecting the base 130 and the front end portion 122A to 122D. The imaginary plane P is located between the vibration arm 121B and the vibration arm 121C.

[0042] Among the four vibration arms 121A to 121D, the vibration arms 121A and 121D are outer vibration arms arranged on the outer side in the X-axis direction, and the vibration arms 121B and 121C are inner vibration arms arranged on the inner side in the X-axis direction. With respect to the imaginary plane P, the inner vibration arm 121B and the inner vibration arm 1121C are symmetrical structures to each other, and the outer vibration arm 121A and the outer vibration arm 121D are symmetrical structures to each other.

[0043] The front end portions 122A to 122D are provided with metal films 125A to 125D on the surface of the upper cover 30 side, respectively. The metal films 125A to 125D function as mass-adding films that make the mass per unit length (hereinafter, simply referred to as "mass") of the front end portions 122A to 122D larger than the mass of the arm portions 123A to 123D. Thus, the metal films 125A to 125D achieve miniaturization of the vibration portion 110 and increase the amplitude. In addition, the metal films 125A to 125D can also be used as so-called frequency adjustment films that adjust the resonance frequency by cutting a portion thereof.

[0044] The width of the front end portion 122A is greater than the width of the arm portion 123A. The same is true for the front end portions 122B to 122D and the arm portions 123B to 123D. Therefore, even if the metal films 125A to 125D are omitted, the weight of each of the front end portions 122A to 122D is greater than the weight of each of the arm portions 123A to 123D. However, the width of each of the front end portions 122A to 122D may be less than the width of each of the arm portions 123A to 123D.

[0045] The shape of each of the front end portions 122A to 122D is a roughly rectangular shape having a curved surface shape (for example, a so-called R shape) with rounded corners at the four corners. The shape of each of the arm portions 123A to 123D is a roughly rectangular shape having an R shape near the root portion connected to the base 130 and near the connection portion connected to the front end portions 122A to 122D respectively. Among them, the shapes of the front end portions 122A to 122D and the arm portions 123A to 123D are not limited to the above. For example, the shapes of the front end portions 122A to 122D may be trapezoidal or L-shaped. In addition, the shapes of the arms 123A to 123D may be trapezoidal, and slits, recesses, protrusions, etc. may be formed in the arms 123A to 123D.

[0046] The shapes and sizes of the vibration arms 121A to 121D are substantially the same. The length of each vibration arm 121A to 121D is, for example, about 450 μm. For example, the length of each arm portion 123A to 123D is about 300 μm, and the width of each arm portion is about 50 μm. For example, the length of each front end portion 122A to 122D is about 150 μm, and the width of each arm portion is about 70 μm.

[0047] The base 130 has a front end 131A, a rear end 131B, a left end 131C, and a right end 131D. The front end 131A, the rear end 131B, the left end 131C, and the right end 131D are respectively a part of the outer edge of the base 130. The front end 131A is an end extending in the X-axis direction on the side of the vibration arms 121A to 121D. The rear end 131B is an end extending in the X-axis direction on the opposite side of the vibration arms 121A to 121D. The left end 131C is an end extending in the Y-axis direction on the vibration arm 121A side when viewed from the vibration arm 121D. The right end 131D is an end extending in the Y-axis direction on the vibration arm 121D side when viewed from the vibration arm 121A. The vibration arms 121A to 121D are connected to the front end 131A.

[0048] The shape of the base 130 is a generally rectangular shape with the front end 131A and the rear end 131B as long sides and the left end 131C and the right end 131D as short sides. An imaginary plane P is defined along the perpendicular bisector of each of the front end 131A and the rear end 131B. The base 130 is not limited to the above structure as long as it is a structure that is generally plane-symmetrical with respect to the imaginary plane P. For example, it may be a trapezoidal shape in which one of the front end 131A and the rear end 131B is longer than the other. In addition, at least one of the front end 131A, the rear end 131B, the left end 131C, and the right end 131D may be bent or curved.

[0049] As an example, the base length, which is the maximum distance between the front end 131A and the rear end 131B in the Y-axis direction, is about 35 μm. Also, as an example, the base width, which is the maximum distance between the left end 131C and the right end 131D in the X-axis direction, is about 265 μm. Figure 3 In the illustrated configuration example, the base length corresponds to the length of the left end portion 131C or the right end portion 131D, and the base width corresponds to the width of the front end portion 131A or the rear end portion 131B.

[0050] like Figure 3As shown, the holding portion 140 has a front frame 141A, a rear frame 141B, a left frame 141C and a right frame 141D. The front frame 141A, the rear frame 141B, the left frame 141C and the right frame 141D are respectively part of a substantially rectangular frame body surrounding the vibration portion 110. Specifically, the front frame 141A is a portion extending in the X-axis direction on the excitation portion 120 side as viewed from the base 130. The rear frame 141B is a portion extending in the X-axis direction on the base 130 side as viewed from the excitation portion 120. The left frame 141C is a portion extending in the Y-axis direction on the vibration arm 121A side as viewed from the vibration arm 121D. The right frame 141D is a portion extending in the Y-axis direction on the vibration arm 121D side as viewed from the vibration arm 121A. The front frame 141A and the rear frame 141B are each bisected by an imaginary plane P.

[0051] The two ends of the left frame 141C are connected to one end of the front frame 141A and one end of the rear frame 141B, respectively. The two ends of the right frame 141D are connected to the other end of the front frame 141A and the other end of the rear frame 141B, respectively. The front frame 141A and the rear frame 141B are opposed to each other in the Y-axis direction via the vibration unit 110. The left frame 141C and the right frame 141D are opposed to each other in the X-axis direction via the vibration unit 110.

[0052] The support arm 150 is disposed inside the holding portion 140 and connects the base 130 and the holding portion 140. Figure 3 In the illustrated configuration example, the support arm 150 includes a left support arm 151A and a right support arm 151B when viewed from the upper cover 30. An imaginary plane P is located between the right support arm 151B and the left support arm 151A, and the right support arm 151B and the left support arm 151A are symmetrical to each other.

[0053] The left support arm 151A connects the rear end portion 131B of the base 130 and the left frame 141C of the holding portion 140. The right support arm 151B connects the rear end portion 131B of the base 130 and the right frame 141D of the holding portion 140. The left support arm 151A has a support rear arm 152A and a support side arm 153A, and the right support arm 151B has a support rear arm 152B and a support side arm 153B.

[0054] The rear support arms 152A and 152B extend from the rear end portion 131B of the base 130 between the rear end portion 131B of the base 130 and the holding portion 140. Specifically, the rear support arm 152A extends from the rear end portion 131B of the base 130 toward the rear frame 141B, bends, and extends toward the left frame 141C. The rear support arm 152B extends from the rear end portion 131B of the base 130 toward the rear frame 141B, bends, and extends toward the right frame 141D. The width of each of the rear support arms 152A and 152B is smaller than the width of each of the vibration arms 121A to 121D.

[0055] The supporting side arm 153A extends along the outer vibration arm 121A between the outer vibration arm 121A and the holding portion 140. The supporting side arm 153B extends along the outer vibration arm 121D between the outer vibration arm 121D and the holding portion 140. Specifically, the supporting side arm 153A extends from the end of the left frame 141C side of the supporting rear arm 152A toward the front frame 141A, bends, and is connected to the left frame 141C. The supporting side arm 153B extends from the end of the right frame 141D side of the supporting rear arm 152B toward the front frame 141A, bends, and is connected to the right frame 141D. The widths of the supporting side arms 153A and 153B are substantially the same as the widths of the supporting rear arms 152A and 152B.

[0056] In addition, the support arm 150 is not limited to the above-mentioned structure. For example, the support arm 150 may be connected to the left end portion 131C and the right end portion 131D of the base portion 130. In addition, the support arm 150 may be connected to the front frame 141A or the rear frame 141B of the holding portion 140. In addition, the number of the support arms 150 may be one or more than three.

[0057] Next, refer to Figure 4 and Figure 5 The structure along the Z-axis direction of the resonance device 1 according to the first embodiment will be described. Figure 4 It is a top view of the interior of the resonance device according to the first embodiment. Figure 5 is a cross-sectional view of the resonance device of the first embodiment. Figure 4 The shape of the lower cover 20 when viewed from the upper cover 30 side is shown. Figure 5 is a diagram for schematically illustrating a stacked structure of the resonance device 1. Figure 5 The components shown are not necessarily located on the same plane of cross section. For convenience, the direction from the lower cover 20 to the upper cover 30 is referred to as "up (upper)", and the direction from the upper cover 30 to the lower cover 20 is referred to as "down (lower)".

[0058] The resonator 10 is held between the lower cover 20 and the upper cover 30. Specifically, the holding portion 140 of the resonator 10 is bonded to the side wall 23 of the lower cover 20 and the side wall 33 of the upper cover 30, respectively. In this way, a vibration space in which the vibration portion 110 can vibrate is formed by the lower cover 20, the upper cover 30, and the holding portion 140. As an example, the resonator 10, the lower cover 20, and the upper cover 30 are each formed using a silicon (Si) substrate. In addition, the resonator 10, the lower cover 20, and the upper cover 30 can also be formed using an SOI (Silicon On Insulator) substrate in which a silicon layer and a silicon oxide film are stacked. In addition, the resonator 10, the lower cover 20, and the upper cover 30 can also be formed using a substrate other than a silicon substrate, such as a compound semiconductor substrate, a glass substrate, a ceramic substrate, a resin substrate, or a substrate composed of a combination thereof, as long as they are substrates that can be processed by micromachining technology.

[0059] like Figure 5 As shown, the resonator 10 has a silicon oxide film F21, a silicon substrate F2, an insulating film F31, a metal film E1, a piezoelectric film F3, a metal film E2, and a protective film F5. The resonator 10 also has the above-mentioned metal films 125A to 125D at the front end portions 122A to 122D. The vibration portion 110, the holding portion 140, and the support arm 150 are formed integrally by the same process. Specifically, the vibration portion 110, the holding portion 140, and the support arm 150 are formed by patterning based on removal processing on a stack composed of the silicon substrate F2, the insulating film F31, the metal film E1, the piezoelectric film F3, the metal film E2, and the protective film F5. The removal processing is performed, for example, by dry etching by irradiating an argon (Ar) ion beam. The removal processing can also be performed by other methods such as wet etching and laser etching.

[0060] The silicon oxide film F21 is provided on the lower surface of the silicon substrate F2 and is sandwiched between the silicon substrate P10 and the silicon substrate F2. The silicon oxide film F21 is made of, for example, SiO 2 The silicon oxide film F21 is formed by silicon oxide such as silicon oxide. A portion of the silicon oxide film F21 is exposed relative to the cavity 21 of the lower cover 20. The silicon oxide film F21 functions as a temperature characteristic compensation layer that reduces the temperature coefficient of the resonant frequency of the resonator 10, that is, the rate of change of the resonant frequency per unit temperature, at least near room temperature. Therefore, the silicon oxide film F21 improves the temperature characteristics of the resonator 10. In addition, the silicon oxide film can be formed on the upper surface of the silicon substrate F2, and can also be formed on both the upper surface and the lower surface of the silicon substrate F2.

[0061] The silicon substrate F2 is formed of a single crystal of silicon. The silicon substrate F2 is formed, for example, of a degenerate n-type silicon (Si) semiconductor having a thickness of about 6 μm. The silicon substrate F2 may contain phosphorus (P), arsenic (As) or antimony (Sb) as an n-type dopant. The resistance value of the degenerate silicon (Si) used in the silicon substrate F2 is, for example, less than 16 mΩ·cm, and more preferably less than 1.2 mΩ·cm.

[0062] The insulating film F31 is provided between the silicon substrate F2 and the metal film E1. The insulating film F31 suppresses the generation of parasitic capacitance and the generation of a short circuit at the end of the resonant device 1. The insulating film F31 is formed of, for example, the same piezoelectric material as the piezoelectric film F3. The material of the insulating film F31 is not limited thereto, and may be, for example, silicon oxide or silicon nitride. In addition, the insulating film F31 may be omitted.

[0063] The metal film E1 is stacked on the insulating film F31, the piezoelectric film F3 is stacked on the metal film E1, and the metal film E2 is stacked on the piezoelectric film F3. The metal films E1 and E2 each have a portion that functions as an excitation electrode for exciting the vibration arms 121A to 121D and a portion that functions as an extraction electrode for electrically connecting the excitation electrode to an external power source. The portion that functions as an excitation electrode in each of the metal films E1 and E2 is opposed to each other in the arm portions 123A to 123D of the vibration arms 121A to 121D via the piezoelectric film F3. The portions of the metal films E1 and E2 that function as extraction electrodes are, for example, extracted from the base 130 to the holding portion 140 via the support arm 150. The metal film E1 is electrically continuous in the entire resonator 10. The metal film E2 is electrically separated in the portion formed in the outer vibration arms 121A and 121D and the portion formed in the inner vibration arms 121B and 121C. The metal film E1 corresponds to an example of a lower electrode, and the metal film E2 corresponds to an example of an upper electrode. In addition, the insulating film F31 may be omitted, and in this case, the metal film E1 is provided on the silicon substrate F2.

[0064] The thickness of each of the metal films E1 and E2 is, for example, about 0.1 μm or more and 0.2 μm or less. After the metal films E1 and E2 are formed, they are patterned into excitation electrodes and extraction electrodes by etching or other removal processes. The metal films E1 and E2 are formed, for example, of a metal material having a body-centered cubic structure. Specifically, the metal films E1 and E2 are formed of Mo (molybdenum), tungsten (W), and the like. In the case where the silicon substrate F2 is a degenerate semiconductor substrate having high conductivity, the metal film E1 may be omitted, and the silicon substrate F2 functions as a lower electrode.

[0065] The piezoelectric film F3 is a thin film formed of a piezoelectric body that converts electrical energy and mechanical energy into each other. The piezoelectric film F3 expands and contracts in the Y-axis direction in the in-plane direction of the XY plane according to the electric field applied between the metal film E1 and the metal film E2. Through the expansion and contraction of the piezoelectric film F3, the vibration arms 121A to 121D are bent so that their open ends are displaced toward the bottom plate 22 of the lower cover 20 and the bottom plate 32 of the upper cover 30. Alternating voltages of opposite phases are applied to the upper electrodes of the outer vibration arms 121A and 121D and the upper electrodes of the inner vibration arms 121B and 121C. Therefore, the outer vibration arms 121A and 121D and the inner vibration arms 121B and 121C vibrate in opposite phases. For example, when the open ends of the outer vibration arms 121A and 121D are displaced toward the lower cover 20, the open ends of the inner vibration arms 121B and 121C are displaced toward the upper cover 30. Such vibrations in opposite phases generate a torsional moment about the rotation axis extending in the Y-axis direction in the vibrating portion 110. The base portion 130 is bent by the torsional moment, and the left end portion 131C and the right end portion 131D are displaced toward the lower cover 20 or the upper cover 30. That is, the vibrating portion 110 of the resonator 10 vibrates in an out-of-plane bending vibration mode.

[0066] The piezoelectric film F3 is formed of a piezoelectric body having a crystal structure of a wurtzite hexagonal crystal structure, for example. As such a piezoelectric body, for example, nitrides or oxides such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), gallium nitride (GaN), and indium nitride (InN) can be cited. In addition, scandium aluminum nitride is a piezoelectric body in which a portion of the aluminum in aluminum nitride is replaced with scandium. Similarly, as a piezoelectric body in which a portion of the aluminum in aluminum nitride is replaced with other elements, a piezoelectric body replaced by two elements of magnesium (Mg) and niobium (Nb), or two elements of magnesium (Mg) and zirconium (Zr) can be cited. The thickness of the piezoelectric film F3 is, for example, about 1 μm, and can also be about 0.2 μm to 2 μm.

[0067] The protective film F5 is stacked on the metal film E2. The protective film F5 protects the metal film E2 from oxidation, for example. The material of the protective film F5 is, for example, an oxide, nitride, or oxynitride containing aluminum (Al), silicon (Si), or tantalum (Ta). A parasitic capacitance reducing film that reduces the parasitic capacitance formed between the internal wirings of the resonator 10 may also be stacked on the protective film F5.

[0068] The metal films 125A to 125D are stacked on the protective film F5 at the front end portions 122A to 122D. The metal films 125A to 125D function as mass addition films and can also function as frequency adjustment films. From the perspective of being a frequency adjustment film, it is preferred that the metal films 125A to 125D are formed of a material whose mass reduction rate based on etching is faster than that of the protective film F5. The mass reduction rate is expressed as the product of the etching rate and the density. The etching rate is the thickness removed per unit time. For the protective film F5 and the metal films 125A to 125D, as long as the relationship between the mass reduction rates is as described above, the magnitude relationship of the etching rates is arbitrary. In addition, from the perspective of being a mass addition film, it is preferred that the metal films 125A to 125D are formed of a material with a large specific gravity. From the above two perspectives, the material of the metal films 125A to 125D is, for example, a metal material such as molybdenum (Mo), tungsten (W), gold (Au), platinum (Pt), nickel (Ni) or titanium (Ti). In addition, when the metal films 125A to 125D are used as frequency adjustment films, a part of the protective film F5 may be removed together with the trimming process of the metal films 125A to 125D. In such a case, the protective film F5 also corresponds to the frequency adjustment film.

[0069] A portion of each of the metal films 125A to 125D is removed by trimming in the frequency adjustment process. The trimming of the metal films 125A to 125D is, for example, dry etching by irradiating an argon (Ar) ion beam. Since the ion beam can irradiate over a wide range, the processing efficiency is excellent, but there is a concern that the metal films 125A to 125D may be charged. In order to prevent the vibration orbits of the vibration arms 121A to 121D from changing due to the Coulomb interaction caused by the charging of the metal films 125A to 125D, thereby causing the vibration characteristics of the resonator 10 to deteriorate, the metal films 125A to 125D are preferably grounded. Therefore, the metal film 125A is electrically connected to the metal film E1 via a through electrode that penetrates the piezoelectric film F3 and the protective film F5. The same is true for the metal films 125B to 125D, which are not shown in the figure, and are electrically connected to the metal film E1 via a through electrode. In addition, the metal films 125A to 125D may be electrically connected to the metal film E1 through, for example, side electrodes provided on the side surfaces of the front end portions 122A to 122D. The metal films 125A to 125D may be electrically connected to the metal film E2.

[0070] Lead wirings C1 and C2 are formed on the protective film F5 of the holding portion 140. The lead wiring C1 is electrically connected to the metal film E1 through a through hole formed in the piezoelectric film F3 and the protective film F5. The lead wiring C2 is electrically connected to the metal film E2 of the outer vibration arms 121A and 121D through a through hole formed in the protective film F5. Although not shown in the figure, lead wiring electrically connected to the metal film E2 of the inner vibration arms 121B and 121C is also formed on the protective film F5. The lead wirings C1 and C2 are formed of a metal material such as aluminum (Al), germanium (Ge), gold (Au) or tin (Sn).

[0071] The bottom plate 22, side wall 23 and limiter 25 of the lower cover 20 are integrally formed by the silicon substrate P10. The silicon substrate P10 is formed of a non-degenerate silicon semiconductor, and its resistivity is, for example, 10Ω·cm or more. The thickness of the lower cover 20 is greater than that of the silicon substrate F2, and is, for example, about 150μm.

[0072] like Figure 4 As shown in FIG. 1 , the limiting portion 25 is provided in an island shape separated from the side wall 23. The limiting portion 25 is opposite to the supporting rear arm 152A of the left supporting arm 151A and the supporting rear arm 152B of the right supporting arm 151B in the thickness direction. The limiting portion 25 is provided in a strip shape with the X-axis direction as the long side direction. Figure 5 As shown in FIG. 1 , the limiting portion 25 protrudes from the bottom plate 22 toward the resonator 10. The distance G2 between the limiting portion 25 and the resonator 10 in the thickness direction is greater than the amplitude of the support arm 150 in the thickness direction during the normal operation of the resonator device 1, and is smaller than the distance between the bottom plate 22 and the resonator 10 in the thickness direction. Since the limiting portion 25 in this embodiment is provided outside the vibration portion 110 in a plan view, the distance G2 may also be smaller than the amplitude of the vibration portion 110 in the thickness direction during the normal operation of the resonator device 1.

[0073] The limiting portion 25 has a metal film M2 at the front end portion opposite to the resonator 10 in the thickness direction. The metal film M2 deforms when the supporting rear arm 152A and the supporting rear arm 152B contact the limiting portion 25 and functions as a buffer film to mitigate the impact. In addition, the metal film M2 also functions as a getter that absorbs hydrogen and organic gases to increase the vacuum degree of the cavities 21 and 31. The metal film M2 is, for example, provided by titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), tantalum (Ta) or an alloy containing at least one of these materials. The metal film M2 can also be provided by a metal having a lower bulk modulus than gold (Au). The metal film M2 is, for example, a single-layer structure, but can also be a multi-layer structure. A diffusion prevention layer to prevent the diffusion of hydrogen and a base layer to improve the adhesion between the metal film M2 and the silicon substrate P10, which are not shown in the figure, can also be provided between the metal film M2 of the limiting portion 25 and the silicon substrate P10.

[0074] In addition, the limiting portion 25 of the present embodiment is configured in an island shape to be opposite to the supporting rear arms 152A and 152B, but the configuration of the limiting portion on the lower cover side of an embodiment of the present invention is not limited to this. From the viewpoint of increasing the surface area and improving the function as a getter, the limiting portion on the lower cover side may also be connected to the side wall of the lower cover. From the same viewpoint, the limiting portion on the lower cover side is not only opposite to the supporting rear arm, but also opposite to at least one of the supporting side arm, the base and the vibration arm. The limiting portion on the lower cover side may also avoid the supporting arm when viewed from above and be opposite to at least one of the base and the vibration arm. In addition, when viewed from above, the limiting portion on the lower cover side may also extend to the outside of the supporting arm and the vibration portion.

[0075] When the resonator 10 and the lower cover 20 are regarded as the MEMS substrate 50, for example, the silicon substrate P10 of the lower cover 20 is equivalent to the supporting substrate (processing layer) of the SOI substrate, the silicon oxide film F21 of the resonator 10 is equivalent to the BOX layer of the SOI substrate, and the silicon substrate F2 of the resonator 10 is equivalent to the active layer (device layer) of the SOI substrate.

[0076] The bottom plate 32, the side wall 33 and the limiting portion 35 of the upper cover 30 are integrally formed by the silicon substrate Q10. A silicon oxide film Q11 is provided on the surface of the silicon substrate Q10. Specifically, the silicon oxide film Q11 is provided in the area between the silicon substrate Q10 and the through electrodes V1 and V2 described later, the area between the silicon substrate Q10 and the internal terminals Y1 and Y2 described later, and the area between the silicon substrate Q10 and the external terminals. The silicon oxide film Q11 prevents short circuits through electrodes and the like of the silicon substrate Q10. In addition, since electrodes and the like that may cause short circuits are not provided on the inner wall of the cavity 31 in the surface of the silicon substrate Q10, the silicon substrate Q10 may be exposed on the inner wall of the cavity 31. The silicon oxide film Q11 is formed, for example, by thermal oxidation of the silicon substrate Q10 or chemical vapor deposition (CVD: Chemical Vapor Deposition). The thickness of the upper cover 30 is, for example, about 150 μm.

[0077] The limiting portion 35 is provided in an island shape separated from the side wall 33, similarly to the limiting portion 25. The limiting portion 35 is opposed to the supporting rear arm 152A of the left supporting arm 151A and the supporting rear arm 152B of the right supporting arm 151B in the thickness direction. When viewed from above, the limiting portion 35 and the limiting portion 25 are substantially overlapped. Figure 5As shown in FIG. 1 , the limiting portion 35 protrudes from the bottom plate 32 toward the resonator 10. The distance G3 between the limiting portion 35 and the resonator 10 in the thickness direction is greater than the amplitude of the support arm 150 in the thickness direction during the normal operation of the resonator device 1, and is smaller than the distance between the bottom plate 32 and the resonator 10 in the thickness direction. For example, the distance G3 is substantially the same as the distance G2. Since the limiting portion 35 in this embodiment is provided outside the vibration portion 110 in a plan view, the distance G3 may also be smaller than the amplitude of the vibration portion 110 in the thickness direction during the normal operation of the resonator device 1.

[0078] The limiting portion 35 has a metal film M3 at the front end portion facing the resonator 10 in the thickness direction. The metal film M3 functions as a buffer film and a getter, similarly to the metal film M2 of the limiting portion 25. The metal film M3 is provided, for example, with the same metal material as the metal film M2. A layer not shown, such as a diffusion prevention layer and a base layer, may also be provided between the metal film M3 of the limiting portion 35 and the silicon substrate Q10.

[0079] In addition, the limiting portion on the upper cover side of an embodiment of the present invention may be connected to the side wall of the upper cover, similar to the limiting portion on the lower cover side, and may be opposite to at least one of the supporting side arm, the base, and the vibration arm. The limiting portion on the upper cover side may also avoid the supporting arm when viewed from above, and may be opposite to at least one of the base and the vibration arm. When viewed from above, the limiting portion on the upper cover side may also extend to the outside of the supporting arm and the vibration portion.

[0080] In addition, when viewed from above, the limiting portion 35 overlaps with the limiting portion 25, and the limiting portion 35 and the limiting portion 25 are approximately the same size, but the positional relationship and size relationship of the limiting portions on the lower cover side and the upper cover side are not limited to this. The limiting portion on the upper cover side of one embodiment of the present invention may also be arranged at a position different from the limiting portion on the lower cover side when viewed from above. For example, the limiting portion on the lower cover side may be opposite to the support arm, and the limiting portion on the upper cover side may be opposite to the base. In addition, the function of the metal film of the larger limiting portion as a getter may be enhanced by making the limiting portion on one of the lower cover side and the upper cover side of one embodiment of the present invention larger than the other.

[0081] In addition, for example, the metal film M3 and the metal film M2 are provided by the same metal material, but they can also be provided by different metal materials. For example, in the limiting portion on the lower cover side and the limiting portion on the upper cover side, the metal film to which a large impact is applied can also be provided by a metal material having a higher impact absorption capacity than the metal film to which a small impact is applied.

[0082] The upper cover 30 is provided with through electrodes V1 and V2. The through electrodes V1 and V2 are provided inside a through hole that penetrates the side wall 33 in the Z-axis direction. The through electrodes V1 and V2 are surrounded by the silicon oxide film Q11 and insulated from each other. The through electrodes V1 and V2 are formed by filling the through hole with polysilicon (Poly-Si), copper (Cu), or gold (Au), for example.

[0083] Internal terminals Y1 and Y2 are provided on the lower surface of the upper cover 30. The internal terminal Y1 is electrically connected to the ground terminal GT through the through electrode V1. The internal terminal Y2 is electrically connected to the power terminal ST2 through the through electrode V2. The internal terminal Y1 is a connection terminal that electrically connects the through electrode V1 and the lead wiring C1. The internal terminal Y2 is a connection terminal that electrically connects the through electrode V2 and the lead wiring C2. In addition, although not shown in the figure, the upper cover 30 is also provided with an internal terminal and a through hole that electrically connects the metal film E2 of the inner vibration arms 121B and 121C to the power terminal ST1.

[0084] The plurality of internal terminals including the internal terminals Y1 and Y2 are electrically insulated from each other by the silicon oxide film Q11. The plurality of external terminals including the ground terminal GT and the power terminal ST2 are also electrically insulated from each other by the silicon oxide film Q11. The plurality of internal terminals and the plurality of external terminals are formed by plating a metallization layer (base layer) of chromium (Cr), tungsten (W), nickel (Ni), etc. with nickel (Ni), gold (Au), silver (Ag), copper (Cu), etc., for example.

[0085] A joint H is formed between the side wall 33 of the upper cover 30 and the holding portion 140 of the resonator 10. When viewed from above, the joint H is arranged in a frame shape that is continuous in the circumferential direction so as to surround the vibration portion 110 and hermetically seal the vibration space formed by the cavities 21 and 31 in a vacuum state. The joint H is formed, for example, by a metal film that is eutectic-bonded by stacking an aluminum (Al) film, a germanium (Ge) film, and an aluminum (Al) film in sequence from the resonator 10 side. The joint H may also include gold (Au), tin (Sn), copper (Cu), titanium (Ti), aluminum (Al), germanium (Ge), silicon (Si), and an alloy containing at least one of these materials. In addition, in order to improve the adhesion between the resonator 10 and the upper cover 30, the joint H may also include an insulator composed of a metal compound such as titanium nitride (TiN) and tantalum nitride (TaN). In addition, the metal films of the joint H are shown as separate layers, but in fact, a eutectic alloy is formed, so there is not necessarily a clear boundary.

[0086] As described above, the upper cover 30 includes the restriction portion 35 for restricting the displacement of the support rear arms 152A and 152B, and the metal film M3 functioning as a getter is provided at the front end portion of the restriction portion 35 .

[0087] Thus, when the resonance device 1 is impacted by falling or the like, the limiting portion 35 contacts the supporting rear arms 152A and 152B to limit the displacement of the vibration portion 110 and the supporting arm 150 toward the upper cover 30. Therefore, damage caused by deformation of the supporting arm 150 toward the upper cover 30 can be suppressed. Moreover, the metal film M3 functions as a buffer film to mitigate the impact caused by the contact between the supporting rear arms 152A and 152B and the limiting portion 35, thereby suppressing the generation of dust caused by the contact between the supporting rear arms 152A and 152B and the limiting portion 35. In addition, the metal film M3 functions as a buffer film and also as a getter. Therefore, the frequency fluctuation caused by the desorption of dust to the vibration portion 110 and the reduction of the vacuum degree of the vibration space can be suppressed. Moreover, compared with a resonance device in which a buffer film and a getter are separately provided on the upper cover, the manufacturing cost can be reduced.

[0088] Furthermore, the lower cover 20 includes a restriction portion 25 for restricting displacement of the support rear arms 152A and 152B, and a metal film M2 functioning as a getter is provided at a front end portion of the restriction portion 25 .

[0089] Thus, it is possible to suppress damage caused by deformation of the support arm 150 toward the lower cover 20, and suppress generation of dust caused by contact between the support rear arms 152A and 152B and the limiting portion 25. Therefore, compared with a structure in which a limiting portion is provided on one of the upper cover and the lower cover, damage to the support arm can be further suppressed, and compared with a structure in which a metal film is provided at the front end of one of the limiting portion of the upper cover and the limiting portion of the lower cover, generation of dust can be further suppressed. In addition, compared with a resonant device in which a buffer film and a getter are provided on the lower cover, respectively, manufacturing costs can be reduced.

[0090] The restricting portions 25 and 35 face the support arm 150 in the thickness direction.

[0091] This makes it possible to suppress abnormal displacement of support arm 150 , which is easily damaged in resonator 10 , without hindering vibration of vibrating portion 110 during normal operation of resonator device 1 .

[0092] As an example, the metal films M2 and M3 are formed of a metal having a lower bulk elastic modulus than gold.

[0093] This can improve the buffer film function of the metal films M2 and M3. In addition, since metals with low bulk elastic modulus tend to have excellent hydrogen absorption function, the decrease in vacuum degree caused by hydrogen in the vibration space of the resonance device 1 can be effectively suppressed.

[0094] Other embodiments are described below. In addition, the same or similar reference numerals are used for the same or similar structures as those shown in the first embodiment, and their description is appropriately omitted. In addition, the same effects brought about by the same structure are not mentioned in sequence.

[0095] <Second embodiment>

[0096] Next, refer to Figure 6 The structure of the resonance device 2 according to the second embodiment will be described. Figure 6 It is a cross-sectional view of a resonance device according to a second embodiment.

[0097] A metal film M21 that functions as a getter is provided on the surface of the bottom plate 22 of the lower cover 220 that faces the resonator 10. A metal film M31 that functions as a getter is provided on the surface of the bottom plate 32 of the upper cover 230 that faces the resonator 10.

[0098] As a result, the volume of the getter increases, and thus the degree of vacuum in the vibration space of the resonance device 2 can be increased.

[0099] The material of the metal film M21 may be the same as that of the metal film M2 .

[0100] Thus, the metal film M21 and the metal film M2 can be provided together by the same process. Similarly, if the material of the metal film M31 is the same as the material of the metal film M3, the metal film M31 and the metal film M3 can be provided together by the same process. Therefore, by suppressing the increase in manufacturing cost and increasing the volume of the getter, the vacuum degree of the vibration space of the resonance device 2 can be improved.

[0101] In addition, the metal film M21 may be provided on the side of the side wall 23 and the limiting portion 25. The metal film M31 may be provided on the side of the side wall 33 and the limiting portion 35.

[0102] <Third Embodiment>

[0103] Next, refer to Figure 7 The structure of the resonance device 3 according to the third embodiment will be described. Figure 7 It is a cross-sectional view of a resonance device according to a third embodiment.

[0104] The distance G3 between the limiting portion 335 of the upper cover 330 and the resonator 10 in the thickness direction is smaller than the distance G2 between the limiting portion 325 of the lower cover 320 and the resonator 10 in the thickness direction. The front end of the limiting portion 335 of the limiting portion 325, 335 having the smaller distance G2, G3 from the resonator 10 is provided by the metal film M3. The front end of the limiting portion 235 of the limiting portion 325, 335 having the larger distance G2, G3 from the resonator 10 is provided by the silicon substrate P10.

[0105] Thus, since the metal film M3 is provided at the tip of the restriction portion 335, which is one of the restriction portions 325 and 335 that is easy to contact the resonator 10, even if the resonance device 3 is subjected to an impact due to falling or the like, the impact acting on the resonator 10 can be mitigated, thereby suppressing damage to the resonator 10. In addition, compared with a resonance device in which a metal film is provided at the tip of the restriction portions of both the lower cover and the upper cover, the step of providing the metal film at the tip of the restriction portion 325 is omitted, thereby reducing the manufacturing cost.

[0106] <Fourth embodiment>

[0107] Next, refer to Figure 8 The structure of the resonance device 4 according to the fourth embodiment will be described. Figure 8 It is a cross-sectional view of a resonance device according to a fourth embodiment.

[0108] The distance G3 between the limiting portion 435 of the upper cover 430 and the resonator 10 in the thickness direction is smaller than the distance G2 between the limiting portion 425 of the lower cover 420 and the resonator 10 in the thickness direction. In the upper cover 430 provided with the limiting portion 435 having the smaller distance G2 or G3 between the limiting portion 425 and the resonator 10, a metal film M31 is provided on the surface of the bottom plate 32 facing the resonator 10.

[0109] Thus, in the process of forming the metal film M3, the metal film M31 can also be formed simultaneously. Therefore, while suppressing an increase in manufacturing cost, the volume of the getter can be increased to improve the vacuum degree of the vibration space of the resonance device 4.

[0110] <Fifth embodiment>

[0111] Next, refer to Fig. 9 The structure of the resonance device 5 according to the fifth embodiment will be described. Fig. 9 is a cross-sectional view of a resonance device according to a fifth embodiment.

[0112] The distance G3 between the limiting portion 535 of the upper cover 530 and the resonator 10 in the thickness direction is smaller than the distance G2 between the limiting portion 525 of the lower cover 520 and the resonator 10 in the thickness direction. In the upper cover 530 provided with the limiting portion 535 having the smaller distance G2, G3 to the resonator 10 among the limiting portions 525 and 535, the bottom plate 532 and a portion of the side wall 533 are provided by the glass substrate Q15. Specifically, the entire bottom plate 532 is provided by the glass substrate Q15, and the periphery of the through electrodes V1 and V2 in the side wall 533 is provided by the glass substrate Q15. The periphery of the through electrode not shown in the figure in the side wall 533 is also provided by the glass substrate Q15. The other portion of the side wall 533 is provided by the silicon substrate Q10. The glass substrate Q15 is made of silicon oxide (for example, SiO 2 ) as the main component of glass. Here, the main component in the glass refers to the component that occupies 50% by mass or more of the overall components constituting the glass. As an example, the glass substrate Q15 is made of SiO 2 Silicate glass is formed as the main component.

[0113] Thus, since the glass substrate Q15 having a smaller electrostatic capacitance than the silicon oxide film Q11 surrounds the through electrodes V1 and V2 , it is possible to reduce parasitic capacitance generated in the through electrodes V1 and V2 .

[0114] In addition, when the silicon oxide film Q11 provided on the bottom plate 532 is thin enough to have sufficient light transmittance, the bottom plate 532 is provided by the glass substrate Q15 having light transmittance, so the resonator 10 can be observed from the outside. Therefore, it is possible to detect a defect that occurs after sealing inside the resonator device 5 by visual inspection. Similarly, when the silicon oxide film Q11 is not provided on at least a part of the bottom plate 532, the resonator 10 can also be observed from the outside.

[0115] In addition, the entire side wall 533 may be formed of the glass substrate Q15. In addition, the bottom plate 532 may be formed of the silicon substrate Q10 and the glass substrate Q15. The restricting portion 535 is formed of the silicon substrate Q10, but may also be formed of the glass substrate Q15.

[0116] In the lower cover 520 provided with the limiting portion 525 having the smaller distance G2 or G3 from the resonator 10, the bottom plate 22 and a part of the side wall 23 may be provided with a glass substrate having silicon oxide as a main component. Regardless of the distance between the limiting portion and the resonator, at least a part of at least one of the lower cover and the upper cover may be provided with a glass substrate having silicon oxide as a main component.

[0117] <Sixth embodiment>

[0118] Next, refer to Fig.10 The structure of the resonance device 6 according to the sixth embodiment will be described. Fig.10 is a cross-sectional view of a resonance device according to a sixth embodiment.

[0119] The distance G3 between the limiting portion 635 of the upper cover 630 and the resonator 10 in the thickness direction is smaller than the distance G2 between the limiting portion 625 of the lower cover 620 and the resonator 10 in the thickness direction. The entire bottom plate 632 is provided by the glass substrate Q15, and the periphery of the through electrodes V1 and V2 in the side wall 633 is provided by the glass substrate Q15. In the upper cover 630, a metal film M31 is provided on the surface of the bottom plate 632 facing the resonator 10.

[0120] Thus, since the conductive metal film M31 covers the inner surface of the bottom plate 632 formed by the insulating glass substrate Q15, the generation of charge on the bottom plate 632 can be suppressed.

[0121] <Seventh embodiment>

[0122] Next, refer to Fig.11 The structure of the resonance device 7 according to the seventh embodiment will be described. Fig.11 It is a top view of the inside of the resonance device according to the seventh embodiment.

[0123] The lower cover 720 has two limiting parts 725A and 725B. The limiting part 725A is opposite to the supporting side arm 153A in the left supporting arm 151A of the supporting arm 150 in the thickness direction. The limiting part 725B is opposite to the supporting side arm 153B in the right supporting arm 151B of the supporting arm 150 in the thickness direction. When viewed from above, the limiting parts 725A and 725B are arranged in a strip shape with the Y-axis direction as the long side direction. The upper cover also has two limiting parts 735A and 735B. The limiting part 735A is opposite to the limiting part 725A in the thickness direction, and the limiting part 735B is opposite to the limiting part 725B in the thickness direction.

[0124] Thus, since the displacement of the support arm 150 is restricted at a position closer to the holding portion 140 than the rear support arms 152A and 152B, damage to the support arm 150 can be more effectively suppressed.

[0125] Like this, the lower cover and the upper cover may each have two or more restricting parts. In addition, the number of restricting parts of the lower cover may be different from the number of restricting parts of the upper cover.

[0126] <Eighth Embodiment>

[0127] Next, refer to Fig.12 The structure of the resonance device 8 according to the eighth embodiment will be described. Fig.12 It is a top view of the interior of the resonance device according to the eighth embodiment.

[0128] In the thickness direction, the limiting portion 825 of the lower cover 820 is opposite to the support arm 150, the base 130 and the excitation portion 120. Specifically, the limiting portion 825 is opposite to the entirety of the supporting rear arms 152A and 152B, to a portion of the side of the supporting side arms 153A and 153B connected to the supporting rear arms 152A and 152B, to the entirety of the base 130, and to a portion of the fixed end side of the vibration arms 121A to 121D. The limiting portion 825 is connected to the entirety of the frame body on the negative direction side of the Y axis, to a portion of the frame body on the positive direction side of the X axis, and to a portion of the frame body on the negative direction side of the X axis in the side wall 23 that is arranged in a frame shape. When viewed from above, the limiting portion 825 is arranged in a strip shape with the X-axis direction as the long side direction. The limiting portion 835 of the upper cover is arranged in the same manner.

[0129] This can increase the area of ​​the tip end portions of the limiting portions 825 and 835. Therefore, by increasing the volume of the getter, the degree of vacuum in the vibration space of the resonance device 8 can be increased.

[0130] As described above, the position of the restricting portion is not limited to the position facing the support arm in the thickness direction, but may be the position facing the vibration portion. The restricting portion may face a part of the open end side of the vibration arm in the thickness direction, or may face the entire vibration arm.

[0131] <Ninth embodiment>

[0132] Next, refer to Fig.13 The structure of the resonance device 9 according to the ninth embodiment will be described. Fig.13 It is a top view of the inside of the resonance device according to the ninth embodiment.

[0133] In the resonator 910, the base 130 is supported by a support arm 950. The support arm 950 connects the rear end portion 131B of the base 130 and the right frame 141D of the holding portion 140. Specifically, the support arm 950 extends from the center portion of the rear end portion 131B in the X-axis direction toward the rear frame 141B, bends and extends toward the right frame 141D, bends and extends toward the front frame 141A, and bends and extends toward the right frame 141D.

[0134] In the thickness direction, the limiting portion 925 of the lower cover 920 is opposite to the excitation portion 120 and the base 130. In addition, the limiting portion 925 is separated from the support arm 950 when viewed from above. The limiting portion 925 is connected to a portion of the frame body on the negative direction side of the X axis and a portion of the frame body on the negative direction side of the Y axis in the side wall 23 that is set in a frame shape. When viewed from above, the limiting portion 925 is set in a triangular shape. The limiting portion 935 of the upper cover is also set in the same way.

[0135] Thus, the restricting portions 925 and 935 can be brought into contact with the excitation portion 120 and the base portion 130 , which have higher mechanical strength than the support arm 950 . This can prevent damage to the resonator 910 caused by contact with the support arm 950 .

[0136] <Tenth embodiment>

[0137] Next, refer to Fig.14 The structure of the resonance device A according to the tenth embodiment will be described. Fig.14 It is a top view of the interior of the resonance device according to the tenth embodiment.

[0138] In the thickness direction, the limiting portion A25 of the lower cover A20 is opposite to the base 130. In the Y-axis direction, the limiting portion A25 is adjacent to the four vibration arms. In addition, when viewed from above, the limiting portion A25 is separated from the excitation portion 120 and the support arm 950. The limiting portion 925 is connected to a portion of the frame on the negative side of the X-axis in the side wall 23 that is set in a frame shape. When viewed from above, the limiting portion A25 is set in a strip shape with the X-axis direction as the long side direction. The limiting portion A35 of the upper cover is also set in the same way.

[0139] Thus, since the restricting portions A25 and A35 can be brought into contact with the base portion 130 having high mechanical strength, damage to the resonator 910 caused by contact with the support arm 950 can be suppressed.

[0140] A part or all of the embodiments of the present invention are described below. In addition, the present invention is not limited to the following descriptions.

[0141] <1> A resonance device comprising:

[0142] A resonator comprising: a vibrating portion; a holding portion disposed at least partially around the vibrating portion; and a supporting arm connecting the vibrating portion and the holding portion; and

[0143] The first substrate comprises a first bottom plate, a first side wall and a first limiting portion, wherein the first bottom plate is spaced apart from the vibration portion in a thickness direction, the first side wall extends from a peripheral portion of the first bottom plate toward the holding portion, and a distance between the first limiting portion and the resonator in the thickness direction is smaller than a distance between the resonator and the first bottom plate.

[0144] A first metal film functioning as a getter is provided at a front end portion of the first restricting portion that faces the resonator in the thickness direction.

[0145] <2> The resonant device according to <1>, wherein:

[0146] The invention also comprises a second substrate, wherein the second substrate comprises a second bottom plate, a second side wall and a second limiting portion, wherein the second bottom plate is arranged to be spaced apart from the vibration portion in the thickness direction, the second side wall extends from the peripheral edge of the second bottom plate toward the holding portion, and the distance between the second limiting portion and the resonator in the thickness direction is smaller than the distance between the resonator and the second bottom plate.

[0147] A second metal film functioning as a getter is provided at a front end portion of the second limiting portion that faces the resonator in the thickness direction.

[0148] <3> The resonant device according to <1>, wherein:

[0149] The invention also comprises a second substrate, wherein the second substrate comprises a second bottom plate, a second side wall and a second limiting portion, wherein the second bottom plate is arranged to be spaced apart from the vibration portion in the thickness direction, the second side wall extends from the peripheral edge of the second bottom plate toward the holding portion, and the distance between the second limiting portion and the vibration portion in the thickness direction is smaller than the distance between the vibration portion and the second bottom plate.

[0150] The distance between the second limiting portion in the thickness direction and the resonator is greater than the distance between the first limiting portion in the thickness direction and the resonator.

[0151] The front end portion of the second limiting portion, which faces the resonator in the thickness direction, is made of silicon or a silicon compound.

[0152] <4> The resonant device according to any one of <1> to <3>, wherein:

[0153] The first metal film is also disposed on the first bottom plate.

[0154] <5> The resonant device according to <2>, wherein:

[0155] The second metal film is also disposed on the second bottom plate.

[0156] <6> The resonant device according to any one of <1> to <5>, wherein

[0157] The first substrate has an internal terminal, an external terminal, and a through electrode, wherein the internal terminal is electrically connected to the resonator, the external terminal is electrically connected to the external substrate, and the through electrode electrically connects the internal terminal and the external terminal.

[0158] The periphery of the through-electrode is formed of glass containing silicon oxide as a main component.

[0159] <7> The resonant device according to any one of <1> to <6>, wherein

[0160] The first substrate has an internal terminal, an external terminal, and a through electrode, wherein the internal terminal is electrically connected to the resonator, the external terminal is electrically connected to the external substrate, and the through electrode electrically connects the internal terminal and the external terminal.

[0161] The first substrate is formed of glass having silicon oxide as a main component.

[0162] <8> The resonant device according to any one of <1> to <7>, wherein

[0163] The first restricting portion faces the support arm in the thickness direction.

[0164] <9> The resonant device according to any one of <1> to <8>, wherein

[0165] The first metal film is provided from titanium or zirconium.

[0166] <10> The resonant device according to any one of <1> to <8>, wherein

[0167] The first metal film is provided by a metal having a lower bulk elastic modulus than gold.

[0168] The embodiments of the present invention are not particularly limited and can be appropriately applied to any device that utilizes the frequency characteristics of a vibrator, such as a timing device, a sound generator, an oscillator, and a load sensor.

[0169] As described above, according to one embodiment of the present invention, it is possible to provide a resonance device capable of suppressing frequency fluctuations.

[0170] In addition, each embodiment described above is for easy understanding of the content of the present invention, and is not for limiting the interpretation of the content of the present invention. The present invention can be changed / improved without departing from its purport, and its equivalent is also included in the present invention. That is, as long as the structure obtained by the technical personnel appropriately applying the design change to each embodiment has the characteristics of the present invention, it is included in the scope of the present invention. For example, each element and its configuration, material, condition, shape, size, etc. possessed by each embodiment are not limited to the content shown in the example and can be appropriately changed. In addition, each element possessed by each embodiment can be combined as much as possible technically, and the structure formed by combining these elements is included in the scope of the present invention as long as it includes the characteristics of the present invention.

[0171] Description of Reference Numerals

[0172] 1…resonance device; 10…resonator; 20…lower cover; 30…upper cover; 21, 31…cavity; 22, 32…bottom plate; 23, 33…side wall; 25, 35…limiting portion; M2, M3…metal film; 50…MEMS substrate; 110…vibration portion; 120…excitation portion; 121A~121D…vibration arm; 130…base; 140…holding portion; 150…support arm.

Claims

1. A resonance device, comprising: A resonator comprising: a vibrating portion; a holding portion disposed at least partially around the vibrating portion; and a supporting arm connecting the vibrating portion and the holding portion; and The first substrate comprises a first bottom plate, a first side wall and a first limiting portion, wherein: The first bottom plate is spaced apart from the vibration portion in a thickness direction, the first side wall extends from a peripheral portion of the first bottom plate toward the holding portion, and a distance between the first limiting portion and the resonator in the thickness direction is smaller than a distance between the resonator and the first bottom plate. A first metal film functioning as a getter is provided at a front end portion of the first restricting portion that faces the resonator in the thickness direction.

2. The resonant device according to claim 1, wherein: The resonant device further comprises a second substrate, the second substrate comprising a second bottom plate, a second side wall and a second limiting portion, wherein the second bottom plate is arranged to be spaced apart from the vibrating portion in the thickness direction, the second side wall extends from the peripheral edge of the second bottom plate toward the holding portion, and the distance between the second limiting portion and the resonator in the thickness direction is smaller than the distance between the resonator and the second bottom plate. A second metal film functioning as a getter is provided at a front end portion of the second restricting portion that faces the resonator in the thickness direction.

3. The resonant device according to claim 1, wherein: The resonant device further comprises a second substrate, the second substrate comprising a second bottom plate, a second side wall and a second limiting portion, wherein the second bottom plate is arranged to be spaced apart from the vibrating portion in the thickness direction, the second side wall extends from the peripheral edge of the second bottom plate toward the holding portion, and the distance between the second limiting portion and the vibrating portion in the thickness direction is smaller than the distance between the vibrating portion and the second bottom plate. The distance between the second limiting portion and the resonator in the thickness direction is greater than the distance between the first limiting portion and the resonator in the thickness direction. A front end portion of the second limiting portion facing the resonator in the thickness direction is made of silicon or a silicon compound.

4. The resonant device according to any one of claims 1 to 3, wherein: The first metal film is also disposed on the first bottom plate.

5. The resonant device according to claim 2, wherein: The second metal film is also disposed on the second bottom plate.

6. The resonant device according to any one of claims 1 to 5, wherein: The first substrate has an internal terminal, an external terminal, and a through electrode, wherein the internal terminal is electrically connected to the resonator, the external terminal is electrically connected to an external substrate, and the through electrode electrically connects the internal terminal and the external terminal. The through-electrode is surrounded by glass containing silicon oxide as a main component.

7. The resonant device according to any one of claims 1 to 6, wherein: The first substrate has an internal terminal, an external terminal, and a through electrode, wherein the internal terminal is electrically connected to the resonator, the external terminal is electrically connected to an external substrate, and the through electrode electrically connects the internal terminal and the external terminal. The first base plate is made of glass containing silicon oxide as a main component.

8. The resonant device according to any one of claims 1 to 7, wherein: The first restriction portion faces the support arm in the thickness direction.

9. The resonant device according to any one of claims 1 to 8, wherein: The first metal film is made of titanium or zirconium.

10. The resonant device according to any one of claims 1 to 8, wherein: The first metal film is made of a metal having a lower bulk elastic modulus than gold.

11. The resonant device according to any one of claims 1 to 10, wherein: The first limiting portion is made of glass containing silicon or silicon oxide as a main component.

12. The resonant device according to any one of claims 1 to 11, wherein: The first bottom plate and the first restricting portion are integrally formed of the same material.

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