Resonant device and manufacturing method thereof

Abstract

The invention provides a resonance device and a manufacturing method thereof. A resonance device (1) is provided with: a resonator (10) having a vibrating part (110), a holding part (140) disposed on at least a part 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 (30) having a first bottom plate (32) provided at a distance from the vibrating part (110) in the thickness direction, and a first side wall (33) extending from the peripheral edge of the first bottom plate (32) toward the holding part (140), the vibrating part (110) having a vibrating arm (121A) configured so as to be able to perform out-of-plane bending vibration, and the first substrate (30) having a second bottom plate (32) provided at a distance from the first bottom plate (32) in the thickness direction and a second side wall (33) extending from the peripheral edge of the first bottom plate (32) toward the holding part (140). A distal end portion (122A) of the vibrating arm (121A) has a base end-side portion provided with a surface facing the first bottom plate (32) via a metal film (125A), and a distal end-side portion positioned closer to the open end side than the base end-side portion and provided with a surface facing the first bottom plate (32) via silicon.

Description

Technical Field

[0001] The present invention relates to a resonant device and a method for manufacturing the same. 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 lower cover, an upper cover, and a resonator having a vibration arm capable of bending and vibrating, wherein the vibration arm has a front end portion having a metal film provided on a side opposite to the upper cover, and a gap between the front end portion of the vibration arm and the upper cover is larger than a gap between the front end portion of the vibration arm and the lower cover.

[0004] Patent Document 1: International Publication No. 2021-117272

[0005] However, in the resonance device described in Patent Document 1, when the resonance frequency is adjusted by making the vibration arm collide with the lower cover or the upper cover, the impact caused by the collision between the vibration arm and the upper cover may be absorbed by the metal film. In such a case, if the gap between the front end of the vibration arm and the upper cover is increased in order to avoid the collision between the vibration arm and the upper cover, the upper cover becomes high, which may hinder the miniaturization of the resonance device. 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 resonant device that can be miniaturized and a method for manufacturing the same.

[0007] A resonance device according to one embodiment of the present invention comprises: a resonator having: a vibration portion; a holding portion, 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, having a first bottom plate and a first side wall, 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 vibration portion has a vibration arm, the vibration arm is configured to be capable of out-of-plane bending vibration, and the front end portion of the vibration arm has: a base end side portion and a front end side portion, wherein the base end side portion is provided with a surface opposite to the first bottom plate by a metal film, and the front end side portion is located on a surface closer to the open end side than the base end side portion and is provided with silicon to be opposite to the first bottom plate.

[0008] A method for manufacturing a resonance device in another embodiment of the present invention, wherein the resonance device comprises: a resonator having: a vibration portion; a holding portion, which is arranged at least in part around the vibration portion; and a support arm, which connects the vibration portion and the holding portion; and a first substrate, which has a first bottom plate and a first side wall, wherein the first bottom plate is arranged to be spaced apart from the vibration portion in the thickness direction, and the first side wall extends from the peripheral portion of the first bottom plate toward the holding portion, the vibration portion has a vibration arm, and the vibration arm is configured to be able to perform out-of-plane bending vibration, and the front end portion of the vibration arm has: a base end side portion and a front end side portion, wherein the base end side portion is provided with a surface opposite to the first bottom plate by a metal film, and the front end side portion is located on a surface closer to the open end side than the base end side portion and is provided with a surface opposite to the first bottom plate by silicon, and the method for manufacturing the resonance device comprises: preparing the resonator; preparing the first substrate; bonding the resonator to the first substrate; and exciting the resonator so that the front end side portion contacts the first bottom plate to adjust the frequency of the resonator.

[0009] According to the present invention, a resonant device that can be miniaturized and a method for manufacturing the same can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a perspective view of the resonance device according to the first embodiment.

[0011] Figure 2 It is an exploded perspective view of the resonance device according to the first embodiment.

[0012] Figure 3 It is a top view of the interior of the resonance device according to the first embodiment.

[0013] Figure 4 It is a cross-sectional view of the resonance device according to the first embodiment.

[0014] Figure 5 1 is a flowchart showing the method for manufacturing the resonance device according to the first embodiment.

[0015] Figure 6 It is a cross-sectional view of a resonance device according to a second embodiment.

[0016] Figure 7 It is a cross-sectional view of a resonance device according to a third embodiment.

[0017] Figure 8 It is a cross-sectional view of a resonance device according to a fourth embodiment.

[0018] Fig. 9 1 is a flowchart showing a method for manufacturing a resonance device according to the fourth embodiment. DETAILED DESCRIPTION

[0019] 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 limited to the embodiments.

[0020] <First embodiment>

[0021] 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 1 It 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.

[0022] Hereinafter, each structure of the resonance device 1 will be described. In each of the drawings, in order to clarify the relationship between the drawings and help understand the positional relationship of each component, an orthogonal coordinate system consisting of an X-axis, a Y-axis, and a Z-axis is sometimes added for convenience. 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.

[0023] The resonator device 1 includes a resonator 10, a lower cover 20, and an upper cover 30. The lower cover 20, the resonator 10, and the upper cover 30 are stacked in sequence 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 is bonded to the lower cover 20 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 are opposed to each other in the thickness direction with the resonator 10 sandwiched therebetween. The lower cover 20 and the upper cover 30 constitute a packaging structure that forms a vibration space inside for the resonator 10 to vibrate. The upper cover 30 is equivalent to an example of a first substrate, and the lower cover 20 is equivalent to an example of a second substrate.

[0024] 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 .

[0025] 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. In the non-vibration state where no voltage is applied, the vibration part 110 extends along the XY plane, and in the vibration state where voltage is applied, the vibration part 110 performs bending vibration in the Z-axis direction. That is, the vibration mode of the vibration part 110 is an out-of-plane bending vibration mode. However, the vibration part 110 in the non-vibration state may also bend in the Z direction due to its own weight.

[0026] In addition, the vibration mode of the vibration portion is not limited to the out-of-plane bending vibration mode, and for example, the vibration mode of the vibration portion may be an in-plane bending vibration mode or a thickness shear vibration mode.

[0027] When looking down at the XY plane (hereinafter, simply referred to as "looking down"), the holding portion 140 is provided in a frame shape, for example, 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.

[0028] 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 .

[0029] 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 portion of the bottom plate 22 toward the upper cover 30. The side wall 23 is a frame-shaped portion surrounding the vibration part 110 when viewed from above. 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 a rectangular parallelepiped opening portion opened toward the vibration part 110.

[0030] The upper cover 30 includes 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 portion 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 portion 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 a rectangular parallelepiped opening portion opened toward the vibration part 110. The cavity 21 and the cavity 31 are opposite to each other with the vibration part 110 interposed therebetween, forming a vibration space of the resonator 10.

[0031] 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". The power terminals ST1 and ST2 are terminals for providing a driving signal (driving voltage) to the resonator 10. The power terminals ST1 and ST2 are 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 a terminal for achieving a balance of electrical characteristics such as electrostatic capacitance and a balance of mechanical strength. The dummy terminal DT is not electrically connected to the resonator 10.

[0032] 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".

[0033] The resonator 10 is formed to be plane-symmetrical with respect to, for example, a virtual plane P parallel to the YZ plane. That is, the shapes of the vibration part 110 , the holding part 140 , and the support arm 150 are formed to be substantially plane-symmetrical with respect to the virtual plane P.

[0034] 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.

[0035] The vibration arms 121A to 121D extend in the Y-axis direction, respectively, and are arranged in the X-axis direction at a prescribed interval in this order. 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 front end portions 122A to 122D arranged on the open end side and arm portions 123A to 123D arranged on the fixed end side. During normal operation of the resonance device 1, the front end portions 122A to 122D are displaced to a greater extent than the front end portions 122A to 122D. The arm portions 123A to 123D connect the base 130 and the front end portions 122A to 122D. The imaginary plane P is located between the vibration arm 121B and the vibration arm 121C.

[0036] Two vibration arms 121A and 121D of the four vibration arms 121A to 121D are outer vibration arms arranged on the outer side in the X-axis direction, and two vibration arms 121B and 121C are inner vibration arms arranged on the inner side in the X-axis direction. The inner vibration arm 121B and the inner vibration arm 121C are mutually symmetrical structures with respect to the imaginary plane P, and the outer vibration arm 121A and the outer vibration arm 121D are mutually symmetrical structures with respect to the imaginary plane P.

[0037] 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 of each of the front end portions 122A to 122D (hereinafter, simply referred to as "mass") larger than the mass of each 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 off a portion thereof.

[0038] 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. Thus, for example, 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.

[0039] The shape of each of the front end portions 122A to 122D is a roughly rectangular shape having a curved surface shape with arcs at the four corners (for example, a so-called R shape). 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. However, the shape of each of the front end portions 122A to 122D and the arm portions 123A to 123D is not limited to the above-mentioned shapes. For example, the shape of each of the front end portions 122A to 122D may be a trapezoidal shape or an L-shape. In addition, the shape of each of the arm portions 123A to 123D may be a trapezoidal shape, and slits, recesses, protrusions, etc. may be formed in the arm portions 123A to 123D.

[0040] 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.

[0041] 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 side of the vibration arm 121A as viewed from the vibration arm 121D. The right end 131D is an end extending in the Y-axis direction on the side of the vibration arm 121D as viewed from the vibration arm 121A. The vibration arms 121A to 121D are connected to the front end 131A.

[0042] The shape of the base 130 is a roughly 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 roughly 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.

[0043] 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.

[0044] like Figure 3 As 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.

[0045] 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.

[0046] 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.

[0047] The left support arm 151A connects the rear end 131B of the base 130 and the left frame 141C of the holding portion 140. The right support arm 151B connects the rear end 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.

[0048] 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.

[0049] The supporting side arm 153A extends along the outer vibrating arm 121A between the outer vibrating arm 121A and the holding portion 140. The supporting side arm 153B extends along the outer vibrating arm 121D between the outer vibrating arm 121D and the holding portion 140. Specifically, the supporting side arm 153A extends from the end of the supporting rear arm 152A on the left frame 141C side 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 supporting rear arm 152B on the right frame 141D side toward the front frame 141A, bends, and is connected to the right frame 141D. The width of each of the supporting side arms 153A and 153B is substantially the same as the width of each of the supporting rear arms 152A and 152B.

[0050] 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.

[0051] Next, refer to Figure 4 The cross-sectional structure of the resonance device 1 according to the first embodiment will be described. Figure 4 is a cross-sectional view of the resonance device of the first embodiment. Figure 4 is a diagram for schematically illustrating the stacked structure of the resonance device 1. Figure 4 The structural 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 (above)", and the direction from the upper cover 30 to the lower cover 20 is referred to as "down (below)".

[0052] 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 may 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 may 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 formed by combining these substrates, as long as they are substrates that can be processed based on micromachining technology.

[0053] like Figure 4 As shown, the resonator 10 includes 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 includes 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 a stack including 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 based on removal processing. 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.

[0054] However, in the front end portions 122A to 122D of the vibration arms 121A to 121D, the base end portion located on the fixed end side of the vibration arms 121A to 121D and the front end portion located on the open end side of the vibration arms 121A to 121D have different components constituting the surface. Specifically, in the base end portion of the front end portion 122A to 122D, a surface opposing the bottom plate 32 of the upper cover 30 is provided through the metal film 125A to 125D. In the front end portion of the front end portion 122A to 122D, a surface opposing the bottom plate 32 of the upper cover 30 is provided through the silicon substrate F2. That is, in the front end portion 122A to 122D, the insulating film F31, the metal film E1, the piezoelectric film F3, the metal film E2, the protective film F5, and the metal films 125A to 125D are provided on the base end portion, but not on the front end portion.

[0055] 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. For example, the silicon oxide film F21 is formed by silicon oxide including SiO2 or the like. 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 acts as a temperature characteristic correction 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 may be formed on the upper surface of the silicon substrate F2, or may be formed on both the upper surface and the lower surface of the silicon substrate F2.

[0056] 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), etc., 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.

[0057] 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.

[0058] 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 at 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 throughout the 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.

[0059] 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 film formation, the metal films E1 and E2 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) or tungsten (W). 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.

[0060] The piezoelectric film F3 is a thin film formed by 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. AC 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 vibrate in opposite phases to the inner vibration arms 121B and 121C. 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.

[0061] The piezoelectric film F3 is formed of a piezoelectric body having a crystal structure of a wurtzite-type hexagonal 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. As a piezoelectric body in which a portion of the aluminum in aluminum nitride is similarly replaced with other elements, a piezoelectric body replaced with 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, but can also be about 0.2 μm to 2 μm.

[0062] 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.

[0063] At the front end portions 122A to 122D, metal films 125A to 125D are stacked on the protective film F5. 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, the metal films 125A to 125D are preferably formed of a material whose mass reduction rate due to 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 so-called etching rate refers to the thickness removed per unit time. As long as the relationship between the mass reduction rates of the protective film F5 and the metal films 125A to 125D is as described above, the magnitude relationship of the etching rates is arbitrary. In addition, from the perspective of being a mass addition film, the metal films 125A to 125D are preferably 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). When the metal films 125A to 125D are used as frequency adjustment films, a portion of the protective film F5 may be removed together with the trimming process of the metal films 125A to 125D. In this case, the protective film F5 also corresponds to the frequency adjustment film.

[0064] 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 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 orbit 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 and deteriorating the vibration characteristics of the resonator 10, it is preferred to ground the metal films 125A to 125D. Therefore, the metal film 125A is electrically connected to the metal film E1 through 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 through the 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.

[0065] 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).

[0066] The bottom plate 22 and the side wall 23 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, 10 Ω·cm or more. The thickness of the lower cover 20 is greater than that of the silicon substrate F2, and is, for example, about 150 μm.

[0067] 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.

[0068] The bottom plate 32 of the upper cover 30 is formed by a glass substrate Q15, and the side wall 33 of the upper cover 30 is formed by a silicon substrate Q10 and a glass substrate Q15. The silicon substrate Q10 is formed by a non-degenerate silicon semiconductor, and its resistivity is, for example, 10Ω·cm or more. The glass substrate Q15 is formed by a glass having silicon oxide (for example, SiO2) as a main component. Here, the main component in the glass refers to a component that occupies more than 50% by mass of all the components constituting the glass. As an example, the glass substrate Q15 is formed by a silicate glass having SiO2 as a main component. The portion surrounding the through electrodes V1 and V2 described later and the portion in contact with the external terminal are formed by the glass substrate Q15. A silicon oxide film Q11 is provided on the lower surface of the side wall 33. The silicon oxide film Q11 electrically separates the internal terminals Y1 and Y2 described later from the silicon substrate Q10. The silicon oxide film Q11 is formed, for example, by chemical vapor deposition (CVD: Chemical Vapor Deposition). The thickness of the upper cover 30 is, for example, approximately 150 μm.

[0069] Furthermore, when the internal terminals Y1 and Y2 are provided outside the silicon substrate Q10 when viewed from above in the thickness direction, the silicon oxide film Q11 may be omitted. When the internal terminals Y1 and Y2 are provided outside the silicon substrate Q10, the silicon oxide film Q11 may be provided only in the region formed by the silicon substrate Q10 in the side wall 33, and omitted in the region formed by the glass substrate Q15.

[0070] The upper cover 30 includes a metal film 70 , through electrodes V1 and V2 , internal terminals Y1 and Y2 , a ground terminal GT, and a power terminal ST2 .

[0071] The metal film 70 is provided on the lower surface of the bottom plate 32 of the upper cover 30. The metal film 70 is a getter that absorbs the gas in the vibration space formed by the cavity 21 of the lower cover 20 and the cavity 31 of the upper cover 30 to improve the vacuum degree, for example, it absorbs hydrogen gas and exhaust gas. The metal film 70, for example, contains titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), tantalum (Ta) or an alloy containing at least one of these metals. The metal film 70 may also contain an oxide of an alkali metal or an oxide of an alkaline earth metal. A layer not shown in the figure, such as a layer for preventing the diffusion of hydrogen from the silicon substrate Q10 to the metal film 70, a layer for improving the adhesion between the silicon substrate Q10 and the metal film 70, may also be provided between the silicon substrate Q10 and the metal film 70.

[0072] The metal film 70 is provided avoiding the region facing the front end portions of the front end portions 122A to 122D in the thickness direction. That is, in the bottom plate 32 of the upper cover 30 , the lower surface is provided via the silicon substrate Q10 in the region facing the front end portions of the front end portions 122A to 122D.

[0073] The through electrodes V1 and V2 are provided on the side wall 33 of the upper cover 30. The through electrodes V1 and V2 are provided inside the through hole that penetrates the side wall 33 in the Z-axis direction. The through electrodes V1 and V2 are surrounded by the glass substrate Q15 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.

[0074] The internal terminals Y1 and Y2 are provided on the lower surface of the side wall 33 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 terminals Y1 and Y2 are electrically insulated from each other by the glass substrate Q15 and the silicon oxide film Q11. The internal terminal Y1 is a connection terminal that electrically connects the through electrode V1 to the lead wiring C1. The internal terminal Y2 is a connection terminal that electrically connects the through electrode V2 to the lead wiring C2. The internal terminals Y1 and Y2 are formed by plating a metallization layer (base layer) of chromium (Cr), tungsten (W), nickel (Ni) or the like with nickel (Ni), gold (Au), silver (Ag), copper (Cu), or the like, for example.

[0075] The ground terminal GT and the power terminal ST2 are provided on the upper surface of the side wall 33 of the upper cover 30. The ground terminal GT and the power terminal ST2 are electrically insulated from each other by the glass substrate Q15. The ground terminal GT and the power terminal ST2 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.

[0076] Although not shown, an internal terminal electrically connecting the metal film E2 of the inner vibration arms 121B and 121C to the power terminal ST1 is provided on the side wall 33 of the upper cover 30. A through electrode not shown is also provided on the side wall 33 of the upper cover 30, and the through electrode electrically connects the internal terminal not shown to the power terminal ST1.

[0077] 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 set to be a frame shape that is continuous in the circumferential direction 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 formed by stacking an aluminum (Al) film, a germanium (Ge) film, and an aluminum (Al) film in sequence from the resonator 10 side and performing eutectic bonding. 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, although the metal films of the joint H are shown as independent layers, in fact, a eutectic alloy is formed, so there is not necessarily a clear boundary.

[0078] In addition, the material of the joint portion H is not limited to the above-mentioned metals, and can be appropriately selected according to the required sealing performance. For example, the joint portion H can also be provided by an organic polymer adhesive or an inorganic glass adhesive.

[0079] At the front end side portions of the front end portions 122A to 122D of the vibration arms 121A to 121D, there are gaps G2 between the vibration arms 121A to 121D and the lower cover 20, and there are gaps G3 between the vibration arms 121A to 121D and the upper cover 30. The gap G2 is the distance in the thickness direction between the front end side portions of the front end portions 122A to 122D of the vibration arms 121A to 121D and the bottom plate 22 of the lower cover 20 when not vibrating. The gap G2 corresponds to the distance in the Z-axis direction between the silicon oxide film F21 and the silicon substrate P10 of the bottom plate 22. The gap G3 is the distance in the thickness direction between the front end side portions of the front end portions 122A to 122D of the vibration arms 121A to 121D and the bottom plate 32 of the upper cover 30 when not vibrating. The gap G3 corresponds to the distance in the Z-axis direction between the silicon substrate F2 and the glass substrate Q15 of the bottom plate 32.

[0080] The gap G3 on the upper cover 30 side is smaller than the gap G2 on the lower cover 20 side. Therefore, when the amplitude of the vibration arms 121A to 121D increases, the vibration arms 121A to 121D contact the upper cover 30 before contacting the lower cover 20. That is, the maximum amplitude of the vibration arms 121A to 121D is limited by the gap G3 on the upper cover 30 side.

[0081] The breaking stress (7.8 GPa) of SiO2, which is the main component of the glass substrate Q15 of the upper cover 30, is higher than the breaking stress (4.4 GPa) of Si, which is the main component of the silicon substrate F2 of the vibration arms 121A to 121D. Therefore, when the vibration arms 121A to 121D collide with the upper cover 30 at a low speed, especially when the external stress acting on the glass substrate Q15 during the collision is less than 7.8 GPa, the Si of the silicon substrate F2 is more easily broken than the SiO2 of the glass substrate Q15. Therefore, in order to suppress the generation of dust from the glass substrate Q15 caused by the collision of the vibration arms 121A to 121D with the upper cover 30, it is preferred that the collision speed of the vibration arms 121A to 121D with the upper cover 30 is low. Therefore, the size of the gap G3 on the upper cover 30 side is preferably less than 12% relative to the length of the vibration arms 121A to 121D, more preferably less than 11%, and further preferably less than 10%. In order to prevent the vibration arms 121A to 121D from contacting the upper cover 30 during normal operation of the resonance device 1 , the size of the gap G3 on the upper cover 30 side is preferably 5% or more, more preferably 6% or more, and even more preferably 7% or more relative to the length of the vibration arms 121A to 121D.

[0082] Furthermore, when the vibration arms 121A to 121D collide with the upper cover 30, the external stress acting on the vibration arms 121A to 121D is greater than the external stress acting on the upper cover 30. Therefore, even if the collision speed of the vibration arms 121A to 121D and the upper cover 30 is low, external stress sufficient to scrape off Si acts on the silicon substrate F2 during the collision.

[0083] Next, refer to Figure 5 A method for manufacturing the resonance device 1 according to the first embodiment will be described. Figure 5 1 is a flowchart showing the method for manufacturing the resonance device according to the first embodiment.

[0084] First, the MEMS substrate 50 is prepared ( S10 ).

[0085] Specifically, first, silicon substrates P10 and F2 that have been mirror-polished on one side are prepared. A cavity 21 is formed on the mirror side of the silicon substrate P10, and a silicon oxide film F21 is formed on the mirror side of the silicon substrate F2. Next, the mirror side of the silicon substrate P10 is brought into contact with the mirror side of the silicon substrate F2 and heat treated to directly bond the silicon substrate P10 to the silicon oxide film F21. Next, an insulating film F31, a metal film E1, a piezoelectric film F3, a metal film E2, a protective film F5, and metal films 125A to 125D are sequentially stacked on the silicon substrate F2 to provide a stacked body constituting the resonator 10. Next, the stacked body is removed by argon ion etching to form the vibration portion 110, the retaining portion 140, and the support arm 150.

[0086] Alternatively, after the vibration portion 110 , the holding portion 140 , and the support arm 150 are formed, the silicon substrate P10 and the silicon oxide film F21 may be directly bonded to each other.

[0087] Next, the metal films 125A to 125D at the front end portions 122A to 122D are ion-etched ( S20 ).

[0088] Specifically, the metal films 125A to 125D are trimmed by ion milling, and the resonance frequency of the resonator 10 is adjusted by the mass change of the vibration arms 121A to 121D. At this time, the surface of the protective film F5 may also be trimmed. Step S20 corresponds to an example of a frequency adjustment process before sealing.

[0089] Next, the upper cover 30 is bonded to the MEMS substrate 50 ( S30 ).

[0090] Specifically, the lower surface of the upper cover 30 is eutectic-bonded to the upper surface of the MEMS substrate 50 through the joint H. First, the upper cover 30 and the MEMS substrate 50 are aligned so that the internal terminals Y1 and Y2 are in contact with the lead-out wirings C1 and C2. After the alignment, the joint H is sandwiched between the upper cover 30 and the MEMS substrate 50, and a heat treatment is performed at a temperature above the eutectic point. The temperature of the heat treatment is, for example, above 424°C, and the heating time of the heat treatment is, for example, about ten minutes to twenty minutes. During heating, the upper cover 30 and the MEMS substrate 50 are pressed with a pressure of, for example, about 5 MPa to 25 MPa.

[0091] Next, the front end portions 122A to 122D of the vibration arms 121A to 121D are caused to collide with the inner wall ( S40 ).

[0092] Specifically, the silicon substrate F2 constituting the upper surface of the front end side portion of the front end portion 122A to 122D is made to collide with the glass substrate Q15 constituting the lower surface of the bottom plate 32 of the upper cover 30. First, a voltage stronger than the electric field applied during normal operation as the resonator device 1 is applied to the resonator 10, so that the resonator 10 vibrates with an amplitude larger than the amplitude during normal operation (hereinafter referred to as "overexcitation"). The front end side portions of the front end portions 122A to 122D of the overexcited vibration arms 121A to 121D collide with the bottom plate 32 of the upper cover 30. At the front end portions 122A to 122D, since the front end side portions collide with the bottom plate 32 first, the base end side portions do not contact the bottom plate 32. Step S40 is equivalent to an example of a frequency adjustment process after sealing.

[0093] As described above, the silicon substrate F2 is used to provide the surfaces of the front end portions 122A to 122D of the vibration arms 121A to 121D that face the bottom plate 32 of the upper cover 30 in the thickness direction.

[0094] Thus, when the vibration arms 121A to 121D collide with the upper cover 30 after sealing to adjust the resonance frequency, the metal films 125A to 125D do not contact the bottom plate 32, but the silicon substrate F2 contacts the bottom plate 32. Since the impact caused by the collision of the vibration arms 121A to 121D with the upper cover 30 is not absorbed by the metal films 125A to 125D, the frequency adjustment process is not hindered by the metal films 125A to 125D. Therefore, there is no need to increase the gap G3 so that the vibration arms 121A to 121D do not collide with the upper cover 30. For example, by making the gap G3 smaller than the gap G2, the upper cover 30 can be made low-profile.

[0095] The surface of the bottom plate 32 facing the front end portions 122A to 122D is provided by a glass substrate Q15 containing silicon oxide as a main component.

[0096] Thus, since the breaking stress of the glass substrate Q15 is greater than the breaking stress of the silicon substrate F2, when the glass substrate Q15 collides with the silicon substrate F2, it is possible to suppress the glass substrate Q15 from being ground and the silicon substrate F2 from being ground. Therefore, the generation of dust from the upper cover 30 can be suppressed in the frequency adjustment process, and the total amount of dust generated in the vibration space can be reduced. In addition, since the glass substrate Q15 is light-transmissive, the resonator 10 can be observed from the outside. Therefore, it is possible to detect defects generated inside the resonator device 1 after sealing by appearance inspection.

[0097] The through electrodes V1 and V2 are surrounded by a glass substrate Q15 containing silicon oxide as a main component.

[0098] 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 .

[0099] 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 descriptions are appropriately omitted. In addition, the same effects brought about by the same structures are not mentioned in sequence.

[0100] <Second embodiment>

[0101] 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.

[0102] The silicon substrate F2 is provided on the surface of the front end portion 222A of the vibration arm 221A facing the bottom plate 22 of the lower cover 20. That is, in the front end portion 222A, the silicon oxide film F21 is provided on the base end portion but not on the front end portion.

[0103] Thus, since the silicon substrate F2, which is easier to grind than the silicon oxide film F21, can collide with the silicon substrate P10 in the frequency adjustment process after sealing, the efficiency of the frequency adjustment process after sealing can be improved. In addition, the dust generated from the front end 222A can be dispersed to both the lower cover 20 and the upper cover 30. If the dust is in a dispersed state, it is small enough and is strongly affected by the van der Waals force, so the dust attached to the lower cover, the upper cover or the resonator is difficult to fall off. Therefore, it is difficult to produce frequency changes caused by the shedding and adhesion of dust. However, if the density of the dust increases, there is a situation where the dust forms a condensate. Since the influence of the van der Waals force on the condensate is lower than the van der Waals force on the dust, the condensate is easier to fall off than the dust. When the front end portion 222A of the vibration arm 221A collides with both the lower cover 20 and the upper cover 30 in the frequency adjustment process after sealing, dust is generated on both the lower cover 20 side and the upper cover 30 side, so the density of the dust can be reduced compared to a structure in which dust is generated only on the upper cover 30 side. Therefore, compared to a structure in which dust is generated only on the upper cover 30 side, the generation of condensed bodies can be suppressed, and the frequency fluctuation caused by the detachment and adhesion of condensed bodies to the resonator 210 can be suppressed.

[0104] The gap G2 on the lower cover 20 side is substantially the same size as the gap G3 on the upper cover 30 side.

[0105] Thereby, the density of dust can be further reduced.

[0106] <Third Embodiment>

[0107] 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.

[0108] The surface of the front end portion 322A of the vibration arm 321A facing the bottom plate 22 of the lower cover 320 is provided by the silicon substrate F2. The surface of the bottom plate 22 of the lower cover 320 facing the front end portion 322A is provided by the silicon oxide film P11. The silicon oxide film P11 is provided on the silicon substrate P10.

[0109] Thus, in the frequency adjustment step after sealing, the silicon substrate F2 can be made to collide with the silicon oxide film P11 which is more difficult to grind than the silicon substrate P10 , and thus generation of dust from the lower cover 320 can be suppressed.

[0110] In addition, the bottom plate of the lower cover may be provided by a glass substrate having silicon oxide as the main component. In this case, since the bottom plate of the lower cover is light-transmissive, the resonator can be observed from the lower cover side outside. Therefore, it is possible to detect defects generated inside the resonator device after sealing by visual inspection.

[0111] <Fourth embodiment>

[0112] Next, refer to Figure 8 and Fig. 9 , the structure of the resonance device 4 of the fourth embodiment and the method for manufacturing the same are described. Figure 8 It is a cross-sectional view of a resonance device according to a fourth embodiment. Fig. 9 1 is a flowchart showing a method for manufacturing a resonance device according to the fourth embodiment.

[0113] like Figure 8 As shown in FIG. 1 , a concave portion RC is formed in the metal film 525A provided at the front end portion 522A of the vibration arm 521A. The concave portion RC is a bottomed groove portion opened on the bottom plate 32 side of the upper cover 30 .

[0114] like Fig. 9 As shown, the method for manufacturing the resonance device 4 further includes, after step S40 , step S50 , in which the metal film 525A of the front end portion 522A is laser etched.

[0115] Specifically, the metal film 525A is trimmed by laser ablation, and the resonant frequency of the resonator 510 is adjusted by the mass change of the vibration arm 521A. Laser is irradiated from the outside through the glass substrate Q15 forming the bottom plate 32 of the upper cover 30. The concave portion RC corresponds to a processing trace of the removal processing based on such laser ablation. Step S50 corresponds to an example of the frequency adjustment process after sealing.

[0116] Thus, since the resonant frequency after sealing can be adjusted by the two steps of adjusting the resonant frequency by overexcitation step S40 and adjusting the resonant frequency by laser ablation step S50, dust generated by the collision of the vibration arm 521A with the lower cover 20 or the upper cover 30 can be reduced in step S40. Therefore, the frequency fluctuation caused by the dust can be suppressed.

[0117] In addition, step S50 may be performed before step S40. In addition, in step S50, in addition to the metal film 525A, the protective film F5 and the like may also be removed by laser ablation. A through hole may be formed in the metal film 525A instead of the concave portion RC. That is, a part of the metal film 525A may be completely removed in the thickness direction by the removal process based on laser ablation in step S50.

[0118] 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.

[0119] <1> A resonance device comprising:

[0120] 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

[0121] The first substrate comprises a first bottom plate and a first side wall, wherein the first bottom plate is arranged to be spaced apart from the vibration part in the thickness direction, and the first side wall extends from the peripheral part of the first bottom plate to the holding part.

[0122] The vibration part has a vibration arm, and the vibration arm is configured to be able to perform out-of-plane bending vibration.

[0123] The front end portion of the vibration arm includes: a base end side portion and a front end side portion, wherein the base end side portion has a surface opposite to the first bottom plate set by a metal film, and the front end side portion is located closer to the open end side than the base end side portion and has a surface opposite to the first bottom plate set by silicon.

[0124] <2> The resonant device according to <1>, wherein:

[0125] The surface of the first bottom plate that is opposite to the front end portion is formed of silicon oxide.

[0126] <3> The resonant device according to <1> or <2>, wherein:

[0127] The first substrate is provided by glass having silicon oxide as a main component.

[0128] <4> The resonant device according to any one of <1> to <3>, wherein:

[0129] 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.

[0130] The periphery of the through electrode is provided with glass containing silicon oxide as a main component.

[0131] <5> The resonant device according to any one of <1> to <4>, wherein

[0132] The resonant device further includes a second substrate, the second substrate having: a second bottom plate and a second side wall, wherein the second bottom plate is provided at a distance from the vibrating portion in a thickness direction, and the second side wall extends from a peripheral portion of the second bottom plate toward the holding portion.

[0133] The surface of the front end portion facing the second bottom plate is formed of silicon.

[0134] <6> The resonant device according to <5>, wherein:

[0135] The surface of the second bottom plate that is opposite to the front end portion is formed of silicon oxide.

[0136] <7> The resonant device according to <5> or <6>, wherein:

[0137] The second substrate is provided by glass having silicon oxide as a main component.

[0138] <8> The resonant device according to any one of <5> to <7>, wherein:

[0139] A gap between the front end side portion in the thickness direction and the first bottom plate is smaller than a gap between the front end side portion in the thickness direction and the second bottom plate.

[0140] <9> The resonant device according to any one of <5> to <7>, wherein:

[0141] A gap between the front end side portion in the thickness direction and the first bottom plate is substantially equal to a gap between the front end side portion in the thickness direction and the second bottom plate.

[0142] <10> The resonant device according to any one of <1> to <9>, wherein

[0143] A recess is formed on the side of the metal film that faces the first bottom plate.

[0144] <11> A method for manufacturing a resonance device, the resonance device comprising:

[0145] 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

[0146] The first substrate comprises a first bottom plate and a first side wall, wherein the first bottom plate is arranged to be spaced apart from the vibration part in the thickness direction, and the first side wall extends from the peripheral part of the first bottom plate to the holding part.

[0147] The vibration part has a vibration arm, and the vibration arm is configured to be able to perform out-of-plane bending vibration.

[0148] The front end portion of the vibration arm includes: a base end portion and a front end portion, wherein the base end portion is provided with a surface facing the first bottom plate through a metal film, and the front end portion is located closer to the open end side than the base end portion and is provided with a surface facing the first bottom plate through silicon.

[0149] The manufacturing method of the above-mentioned resonance device comprises:

[0150] Prepare the resonator;

[0151] preparing a first substrate;

[0152] bonding the resonator to the first substrate; and

[0153] The resonator is excited so that the front end portion contacts the first bottom plate to adjust the frequency of the resonator.

[0154] <12> The method for manufacturing a resonance device according to <11>, wherein:

[0155] The surface of the first bottom plate that is opposite to the front end portion is formed of silicon oxide.

[0156] <13> The method for manufacturing a resonance device according to <11> or <12>, wherein:

[0157] The first substrate is provided by glass having silicon oxide as a main component.

[0158] <14> The method for manufacturing a resonance device according to any one of <11> to <13>, further comprising:

[0159] The frequency of the resonator is adjusted by irradiating the metal film with laser light from the outside through the first bottom plate.

[0160] <15> The method for manufacturing a resonance device according to any one of <11> to <14>, wherein:

[0161] The device further comprises a second substrate, wherein the second substrate comprises a second bottom plate and a second side wall, wherein the second bottom plate is spaced apart from the vibration portion in the thickness direction, and the second side wall extends from the peripheral portion of the second bottom plate toward the holding portion.

[0162] The surface of the front end portion facing the second bottom plate is provided by silicon,

[0163] Adjusting the frequency of the resonator includes exciting the resonator so that the front end side portion contacts the second bottom plate.

[0164] <16> The method for manufacturing a resonance device according to <15>, wherein:

[0165] The surface of the second bottom plate that is opposite to the front end portion is formed of silicon oxide.

[0166] The embodiments of the present invention are not particularly limited and can be appropriately applied to any device that utilizes the frequency characteristics of an oscillator, such as a timing device, a sound generator, an oscillator, or a load sensor.

[0167] As described above, according to one aspect of the present invention, a resonant device that can be reduced in size and a method for manufacturing the same can be provided.

[0168] In addition, the above-described embodiment is an embodiment for facilitating the understanding of the present invention, and is not an embodiment for limiting the interpretation of the present invention. The present invention can be changed / improved within the scope of its purport, and the present invention also includes its equivalent. That is, as long as the features of the present invention are possessed, the embodiments formed by appropriately applying design changes to each embodiment by those skilled in the art are also 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 illustrated content 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 also included in the scope of the present invention as long as it includes the features of the present invention.

[0169] Description of Reference Numerals

[0170] 1…resonance device, 10…resonator, 20…lower cover, 30…upper cover, 21, 31…cavity, 22, 32…bottom plate, 23, 33…side wall, 50…MEMS substrate, 70…metal film, 110…vibration part, 120…excitation part, 121A~121D…vibration arm, 122A~122D…front end part, 125A~125D…metal film, 130…base, 140…holding part, 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 has a first bottom plate and a first side wall, wherein: The first bottom plate is disposed at a distance from the vibrating portion in a thickness direction, and the first side wall extends from a peripheral portion of the first bottom plate toward the holding portion. The vibration part has a vibration arm, and the vibration arm is configured to be capable of out-of-plane bending vibration. The front end portion of the vibration arm includes: a base end side portion and a front end side portion, wherein the base end side portion is provided with a surface opposite to the first bottom plate through a metal film, and the front end side portion is located closer to the open end side than the base end side portion and is provided with a surface opposite to the first bottom plate through silicon.

2. The resonant device according to claim 1, wherein: The surface of the first bottom plate facing the front end portion is formed of silicon oxide.

3. The resonant device according to claim 1 or 2, wherein: The first base plate is formed of glass having silicon oxide as a main component.

4. The resonant device according to any one of claims 1 to 3, 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 periphery of the through electrode is provided with glass containing silicon oxide as a main component.

5. The resonant device according to any one of claims 1 to 4, wherein: The resonant device further includes a second substrate, the second substrate having: a second bottom plate and a second side wall, wherein the second bottom plate is arranged at a distance from the vibrating portion in the thickness direction, and the second side wall extends from a peripheral portion of the second bottom plate toward the holding portion. The surface of the front end portion facing the second bottom plate is formed of silicon.

6. The resonance device according to claim 5, wherein: The surface of the second bottom plate facing the front end portion is formed of silicon oxide.

7. The resonant device according to claim 5 or 6, wherein: The second substrate is formed of glass having silicon oxide as a main component.

8. The resonant device according to any one of claims 5 to 7, wherein: A gap between the front end side portion in the thickness direction and the first bottom plate is smaller than a gap between the front end side portion in the thickness direction and the second bottom plate.

9. The resonant device according to any one of claims 5 to 7, wherein: A gap between the front end side portion in the thickness direction and the first bottom plate is substantially equal to a gap between the front end side portion in the thickness direction and the second bottom plate.

10. The resonant device according to any one of claims 1 to 9, wherein: A recess is formed on a side of the metal film that faces the first bottom plate.

11. A method for manufacturing a resonance device, the 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 has a first bottom plate and a first side wall, wherein: The first bottom plate is disposed at a distance from the vibrating portion in a thickness direction, and the first side wall extends from a peripheral portion of the first bottom plate toward the holding portion. The vibration part has a vibration arm, and the vibration arm is configured to be capable of out-of-plane bending vibration. The front end portion of the vibration arm includes: a base end portion and a front end portion, wherein the base end portion is provided with a surface facing the first bottom plate through a metal film, and the front end portion is located closer to the open end side than the base end portion and is provided with a surface facing the first bottom plate through silicon. The manufacturing method of the above-mentioned resonance device comprises: preparing the above resonator; preparing the first substrate; bonding the resonator to the first substrate; and The resonator is excited so that the front end portion contacts the first bottom plate to adjust the frequency of the resonator.

12. The method for manufacturing a resonance device according to claim 11, wherein: The surface of the first bottom plate facing the front end portion is formed of silicon oxide.

13. The method for manufacturing a resonance device according to claim 11 or 12, wherein: The first base plate is formed of glass having silicon oxide as a main component.

14. The method for manufacturing a resonance device according to any one of claims 11 to 13, wherein: Also includes: The frequency of the resonator is adjusted by irradiating the metal film with laser light from the outside through the first bottom plate.

15. The method for manufacturing a resonance device according to any one of claims 11 to 14, wherein: The device further comprises a second substrate, wherein the second substrate comprises: a second bottom plate and a second side wall, wherein the second bottom plate is arranged at a distance from the vibration part in the thickness direction, and the second side wall extends from the peripheral portion of the second bottom plate toward the holding part. The surface of the front end portion facing the second bottom plate is provided with silicon, Adjusting the frequency of the resonator includes exciting the resonator so that the front end portion contacts the second bottom plate.

16. The method for manufacturing a resonance device according to claim 15, wherein: The surface of the second bottom plate facing the front end portion is formed of silicon oxide.

Images