Resonator and resonator device

Abstract

The present invention provides a resonator and a resonant device that improves DLD while suppressing the decrease in the resonant frequency adjustment rate. The resonator (10) includes: a vibrating part (110) comprising a plurality of vibrating arms (121A to 121D) and a base (130), wherein at least two vibrating arms are bent out of plane at different phases; a holding part (140) configured to hold the vibrating part (110); and a support arm (151) having one end connected to the holding part (140) and the other end connected to the rear end (131B) of the base (130). When viewed from above, the other end of the support arm (151) is connected to a position in the range of -0.1WB to 0.1WB relative to the base width WB of the base (130) when the position through which the center line (CL1) of the rear end (131B) of the base (130) passes is taken as a reference. The support arm length LS of the support arm (151) is more than 0.2 times and less than 0.4 times the vibrating arm length LA of the vibrating arms (121A to 121D).

Description

Technical Field

[0001] The present invention relates to a resonator and a resonator device in which multiple vibrating arms vibrate in an out-of-plane bending vibration mode. Background Technology

[0002] Previously, resonant devices using MEMS (Micro Electro Mechanical Systems) technology were used, for example, as timing devices. These resonant devices are mounted on printed circuit boards disposed within electronic devices such as smartphones. The resonant device includes a lower substrate, an upper substrate forming a cavity between the lower substrate and the upper substrate, and a resonator disposed within the cavity between the lower substrate and the upper substrate.

[0003] For example, Patent Document 1 discloses a resonator in which the resonant frequency is changed by over-exciting the vibrating arm and causing the adjustment diaphragm at the front end of the vibrating arm to collide with the upper or lower substrate.

[0004] Patent Document 1: International Publication No. 2016 / 175218

[0005] On the other hand, in recent years, there has been a demand for improving the drive level dependence (DLD) of the resonator, which is expressed as the rate of change of the resonant frequency relative to the excitation level.

[0006] However, there are cases where improvements to the DLD's construction reduce the resonant frequency adjustment rate during the frequency tuning process. Such resonators are time-consuming to manufacture, raising concerns about reduced manufacturing efficiency. Summary of the Invention

[0007] The present invention was made in view of the following circumstances, and one of its objectives is to provide a resonator and a resonant device that can improve DLD and suppress the decrease in the adjustment rate of the resonant frequency.

[0008] One aspect of the resonator according to the present invention comprises: a vibrating part including a plurality of vibrating arms and a base, wherein the plurality of vibrating arms are three or more vibrating arms each having a fixed end, wherein at least two vibrating arms are bent out of plane at different phases, the base having one end connected to the fixed end of each of the plurality of vibrating arms and another end opposite to the fixed end; a holding part configured to hold the vibrating part; and a support arm, one end of the support arm being connected to the holding part, and the other end of the support arm being connected to the other end of the base, wherein, in plan view, the other end of the support arm is connected at a position relative to the base width WB in the range of -0.1WB to 0.1WB, with the position through which the center line of the vibrating part at the other end of the base passes as a reference, and the base width WB being the length of the base in the direction orthogonal to the center line, and the length of the support arm in the direction parallel to the long side direction of the vibrating part being 0.2 times or more and 0.4 times or less than the length of the vibrating arm in the long side direction.

[0009] One aspect of the resonant device according to the present invention includes the above-described resonator.

[0010] According to the present invention, the DLD can be improved and the decrease in the resonant frequency adjustment rate can be suppressed. Attached Figure Description

[0011] Figure 1 This is a perspective view schematically showing the appearance of a resonant device in one embodiment.

[0012] Figure 2 It is a schematic representation Figure 1 An exploded perspective view of the structure of the resonant device shown.

[0013] Figure 3 It is a schematic representation Figure 2 The diagram shows a top view of the construction of a harmonic oscillator.

[0014] Figure 4 It is a schematic representation Figure 1 A cross-sectional view along the X-axis of the stacked structure of the resonant device shown.

[0015] Figure 5 It is a schematic representation Figure 1 A cross-sectional view along the Y-axis of the stacked structure of the resonant device shown.

[0016] Figure 6 It is used for explanation Figure 3 A top view showing the dimensions of the harmonic oscillator.

[0017] Figure 7 It is a graph showing the relationship between the length of each support arm, the connection position of the support arm on the base, and the frequency change rate per unit power.

[0018] Figure 8 It is a graph showing the relationship between the length of the support arm and the connection position of the support arm on the base.

[0019] Figure 9 This is a schematic cross-sectional view showing the displacement of the vibrating arm when the connection position of the support arm is -10μm.

[0020] Figure 10 This is a schematic cross-sectional view showing the displacement of the vibrating arm when the connection position of the support arm is -50μm.

[0021] Figure 11 It is a graph showing the relationship between the connection position of the support arm on the base and the displacement of the vibrating arm.

[0022] Figure 12 It is a graph showing the relationship between the adjustment time and the rate of change of the resonant frequency based on the overexcitation resonant frequency for each support arm length and each connection position of the support arm.

[0023] Figure 13 It is a graph showing the relationship between the connection position of the support arm on the base and the adjustment rate based on the overexcitation resonant frequency.

[0024] Figure 14 It is a graph showing the relationship between the length of the support arm and the connection position of the support arm on the base. Detailed Implementation

[0025] The embodiments of the present invention will be described below. In the following drawings, the same or similar reference numerals denote the same or similar constituent elements. The drawings are illustrative, and the dimensions and shapes of the parts are schematic and should not be construed as limiting the scope of the present invention to these embodiments.

[0026] First, refer to Figure 1 as well as Figure 2 The general structure of a resonant device according to one embodiment will be described. Figure 1 This is a perspective view schematically showing the appearance of the resonant device 1 in one embodiment. Figure 2 It is a schematic representation Figure 1 An exploded perspective view of the structure of the resonant device 1 shown.

[0027] The resonant device 1 includes a lower cover 20, a resonator 10, and an upper cover 30. That is, the resonant device 1 is constructed by sequentially stacking the lower cover 20, the resonator 10, and the upper cover 30. The lower cover 20 and the upper cover 30 are configured to sandwich the resonator 10 and face each other. Furthermore, the lower cover 20 and the upper cover 30 are an example of the "cover" of the present invention.

[0028] The structure of the resonant device 1 will be described below. In the following description, the side of the resonant device 1 where the upper cover 30 is provided will be referred to as the upper (or the top), and the side where the lower cover 20 is provided will be referred to as the lower (or the back).

[0029] The resonator 10 is a MEMS oscillator manufactured using MEMS technology. The resonator 10 is bonded to the lower cover 20 and the upper cover 30 to seal the resonator 10 and form a vibration space for it. Furthermore, the resonator 10, the lower cover 20, and the upper cover 30 are formed using silicon (Si) substrates (hereinafter referred to as "Si substrates"), which are bonded together. Alternatively, the resonator 10, the lower cover 20, and the upper cover 30 can also be formed using SOI (Silicon On Insulator) substrates that have stacked silicon layers and silicon oxide films.

[0030] The lower cover 20 includes a rectangular flat base plate 22 arranged along the XY plane and a sidewall 23 extending from the periphery of the base plate 22 toward the Z-axis, which is the stacking direction of the lower cover 20 and the resonator 10. In the lower cover 20, a recess 21 is formed on the surface opposite the resonator 10, defined by the surface of the base plate 22 and the inner surface of the sidewall 23. The recess 21 forms at least a portion of the vibration space of the resonator 10. Alternatively, the lower cover 20 may not have the recess 21 and may be a flat plate structure. Furthermore, an air-absorbing layer may be formed on the resonator 10 side surface of the recess 21 of the lower cover 20.

[0031] Additionally, the lower cover 20 has a protrusion 50 formed on the surface of the base plate 22. The detailed structure of the protrusion 50 will be described later.

[0032] The top cover 30 has a rectangular flat base plate 32 arranged along the XY plane and a sidewall 33 extending from the periphery of the base plate 22 in the Z-axis direction. In the top cover 30, a recess 31 is formed on the surface opposite the resonator 10, defined by the surface of the base plate 32 and the inner surface of the sidewall 33. The recess 31 forms at least a portion of the space where the resonator 10 vibrates, i.e., the vibration space. Alternatively, the top cover 30 may not have the recess 31 and may have a flat plate structure. Additionally, an air-absorbing layer may be formed on the resonator 10 side surface of the recess 31 of the top cover 30.

[0033] By joining the upper cover 30, the resonator 10, and the lower cover 20, the vibration space of the resonator 10 is airtightly sealed, maintaining a vacuum state. Alternatively, the vibration space can be filled with a gas such as an inert gas.

[0034] Next, refer to Figure 3 The general structure of the harmonic oscillator according to the first embodiment will be described. Figure 3 It is a schematic representation Figure 2The diagram shows a top view of the structure of the harmonic oscillator 10.

[0035] like Figure 3 As shown, the resonator 10 is a MEMS oscillator manufactured using MEMS technology. Figure 3 The vibration occurs primarily in the out-of-plane bending vibration mode (hereinafter also referred to as the "main mode") in the XY plane of the orthogonal coordinate system.

[0036] The resonator 10 includes a oscillating part 110, a holding part 140, and a support arm 151.

[0037] The vibrating part 110 has a longitudinal direction Figure 3 The outline of a rectangle extended in the XY plane of an orthogonal coordinate system. The vibrating part 110 is disposed inside the holding part 140, and a space is formed between the vibrating part 110 and the holding part 140 at a predetermined interval. Figure 3 In this example, the vibration unit 110 includes an excitation unit 120 consisting of four vibration arms 121A to 121D (hereinafter collectively referred to as "vibration arms 121") and a base 130. Furthermore, the number of vibration arms is not limited to four; for example, it can be any number of three or more. In this embodiment, the excitation unit 120 and the base 130 are integrally formed.

[0038] Vibration arms 121A, 121B, 121C, and 121D extend along the Y-axis and are arranged side-by-side at predetermined intervals along the X-axis. One end of vibration arm 121A is a fixed end connected to the front end portion 131A of the base 130 (described later), and the other end is an open end located away from the front end portion 131A of the base 130. Vibration arm 121A includes a mass attachment portion 122A formed on the open end side and an arm portion 123A extending from the fixed end and connected to the mass attachment portion 122A. Similarly, vibration arms 121B, 121C, and 121D also include mass attachment portions 122B, 122C, and 122D, and arm portions 123B, 123C, and 123D, respectively. Furthermore, the arm portions 123A to 123D have, for example, a width of approximately 26 μm in the X-axis direction and a length of approximately 246 μm in the Y-axis direction.

[0039] In the excitation unit 120 of this embodiment, two vibrating arms 121A and 121D are arranged on the outer side in the X-axis direction, and two vibrating arms 121B and 121C are arranged on the inner side. The width of the gap (hereinafter referred to as the "release width") formed between the arm portions 123B and 123C of the two inner vibrating arms 121B and 121C is set to be larger than, for example, the release width W2 between the arm portions 123A and 123B of the adjacent vibrating arms 121A and 121B in the X-axis direction, and the release width W2 between the arm portions 123D and 123C of the adjacent vibrating arms 121D and 121C in the X-axis direction. The release width W1 is, for example, about 40 μm, and the release width W2 is, for example, about 18 μm. In this way, by setting the release width W1 to be larger than the release width W2, the vibration characteristics and durability of the vibrating unit 110 can be improved. In addition, in order to miniaturize the resonant device 1, the release width W1 can be set to be smaller than the release width W2, or it can be set to be equally spaced.

[0040] The mass-adding parts 122A to 122D each have mass-adding films 125A to 125D on their respective surfaces. Therefore, the weight per unit length of each of the mass-adding parts 122A to 122D (hereinafter referred to simply as "weight") is greater than the weight of each of the arm parts 123A to 123D. This allows for miniaturization of the vibrating part 110 while improving vibration characteristics. Furthermore, the mass-adding films 125A to 125D not only function to increase the weight of the front ends of the vibrating arms 121A to 121D, but also function as frequency-adjusting films, allowing adjustment of the resonant frequency of the vibrating arms 121A to 121D by removing a portion of them.

[0041] In this embodiment, the width of each of the mass attachments 122A to 122D along the X-axis is, for example, about 49 μm, which is larger than the width of each of the arms 123A to 123D along the X-axis. This allows for a further increase in the weight of each of the mass attachments 122A to 122D. For miniaturization of the resonator 10, it is preferable that the width of each of the mass attachments 122A to 122D along the X-axis is at least 1.5 times greater than the width of each of the arms 123A to 123D along the X-axis. However, the width of each of the mass attachments 122A to 122D along the X-axis is not limited to the example of this embodiment, as long as the weight of each of the mass attachments 122A to 122D is greater than the weight of each of the arms 123A to 123D. The width of each of the mass attachments 122A to 122D along the X-axis may also be equal to or less than the width of each of the arms 123A to 123D along the X-axis.

[0042] When viewed from above (hereinafter referred to as "top view"), the mass attachments 122A to 122D are generally rectangular, with curved surfaces having rounded corners, such as an R-shape. Similarly, the arms 123A to 123D are generally rectangular, with an R-shape near the fixed end connected to the base 130 and near the connecting portions connected to the mass attachments 122A to 122D. However, the shapes of the mass attachments 122A to 122D and the arms 123A to 123D are not limited to the example of this embodiment. For example, the shapes of the mass attachments 122A to 122D may also be generally trapezoidal or generally L-shaped. In addition, the shapes of the arms 123A to 123D may also be generally trapezoidal. The mass attachments 122A to 122D and the arm portions 123A to 123D may also be formed as bottomed grooves with openings on either the surface side or the back side, or as holes with openings on both the surface side and the back side. The grooves and holes may be located away from the side connecting the surface and the back side, or they may have openings on that side.

[0043] When viewed from above, the base 130 has a front end 131A, a rear end 131B, a left end 131C, and a right end 131D. As described above, the fixed ends of the vibrating arms 121A to 121D are connected to the front end 131A. A support arm 151 is connected to the rear end 131B.

[0044] The front end portion 131A, rear end portion 131B, left end portion 131C, and right end portion 131D are all parts of the outer edge portion of the base 130. Specifically, the front end portion 131A and the rear end portion 131B are ends extending in the X-axis direction, and are configured to face each other. The left end portion 131C and the right end portion 131D are ends extending in the Y-axis direction, and are configured to face each other. The two ends of the left end portion 131C are connected to one end of the front end portion 131A and one end of the rear end portion 131B, respectively. The two ends of the right end portion 131D are connected to the other end of the front end portion 131A and the other end of the rear end portion 131B, respectively.

[0045] Viewed from above, the base 130 is approximately rectangular, with the front end 131A and rear end 131B as its long sides and the left end 131C and right end 131D as its short sides. The base 130 is formed approximately symmetrically with respect to a virtual plane defined by the center line CL1 along the perpendicular bisecting lines of the front end 131A and rear end 131B, i.e., the X-axis direction. That is, it can be said that the base 130 is formed approximately linearly symmetrical about the center line CL1. Furthermore, the shape of the base 130 is not limited to… Figure 3The rectangular shape shown could also be other shapes that are approximately line-symmetrical about the center line CL1. For example, the shape of the base 130 could also be a trapezoidal shape in which one of the front end 131A and the rear end 131B is longer than the other. Alternatively, at least one of the front end 131A, the rear end 131B, the left end 131C, and the right end 131D could be bent or folded.

[0046] Furthermore, the virtual plane corresponds to the plane of symmetry of the entire vibrating section 110, and the center line CL1 corresponds to the center line of the entire vibrating section 110 in the X-axis direction. Therefore, the center line CL1 is also a line passing through the center of the vibrating arms 121A to 121D in the X-axis direction, located between vibrating arms 121B and 121C. Specifically, adjacent vibrating arms 121A and 121B are symmetrically formed with adjacent vibrating arms 121D and 121C, respectively, separated by the center line CL1.

[0047] In the base 130, the longest distance in the Y-axis direction between the front end portion 131A and the rear end portion 131B, i.e., the base length, is for example approximately 25 μm. Additionally, the longest distance in the X-axis direction between the left end portion 131C and the right end portion 131D, i.e., the base width, is for example approximately 180 μm. Furthermore, in... Figure 3 In the example shown, the base length is equivalent to the length of the left end 131C or the right end 131D, and the base width is equivalent to the length of the front end 131A or the rear end 131B.

[0048] The holding part 140 is configured to hold the vibrating part 110. More specifically, the holding part 140 is configured such that the vibrating arms 121A to 121D can vibrate. Specifically, the holding part 140 is formed symmetrically with respect to a virtual plane defined along the center line CL1. The holding part 140 has a rectangular frame shape when viewed from above, and is arranged along the XY plane to surround the outer side of the vibrating part 110. In this way, by having a frame shape when viewed from above, the holding part 140 surrounding the vibrating part 110 can be easily realized.

[0049] Furthermore, the retaining part 140 need only be disposed around at least a portion of the vibrating part 110, and is not limited to a frame shape. For example, the retaining part 140 need only be disposed around the vibrating part 110 to a degree that can retain the vibrating part 110 and can also engage with the upper cover 30 and the lower cover 20.

[0050] In this embodiment, the holding part 140 includes integrally formed frame bodies 141A to 141D. For example... Figure 3As shown, frame 141A is positioned opposite the open ends of vibrating arms 121A-121D, with its long side parallel to the X-axis. Frame 141B is positioned opposite the rear end 131B of base 130, with its long side parallel to the X-axis. Frame 141C is positioned opposite the left end 131C of base 130 and vibrating arm 121A, with its long side parallel to the Y-axis, and its two ends are connected to one end of frames 141A and 141B respectively. Frame 141D is positioned opposite the right end 131D of base 130 and vibrating arm 121D, with its long side parallel to the Y-axis, and its two ends are connected to the other ends of frames 141A and 141B respectively. Frames 141A and 141B sandwich the vibrating part 110 and are positioned opposite each other in the Y-axis direction. The frame 141C and the frame 141D sandwich the vibrating part 110 and are positioned opposite each other in the X-axis direction.

[0051] The support arm 151 is disposed inside the retaining portion 140, connecting the base 130 to the retaining portion 140. When viewed from above, the support arm 151 is not symmetrical about the center line CL1, i.e., asymmetrical. Specifically, the support arm 151 includes a rear support arm 152 and a side support arm 153.

[0052] The support arm 153 extends parallel to the vibrating arm 121D between the vibrating arm 121D and the retaining part 140. Specifically, the support arm 153 extends from one end (the right end or the end on the side of the frame 141D) of the support rear arm 152 toward the frame 141A in the Y-axis direction and bends in the X-axis direction to connect with the frame 141D. That is, one end of the support arm 151 is connected to the retaining part 140.

[0053] The rear support arm 152 extends from the support side arm 153 between the rear end portion 131B of the base 130 and the retaining portion 140. Specifically, the rear support arm 152 extends towards the frame 141C in the X-axis direction from one end (the lower end or the end on the side of the frame 141B) of the support side arm 153. Then, the rear support arm 152 bends in the Y-axis direction near the center of the base 130 in the X-axis direction, and extends parallel to the centerline CL1 from there, connecting with the rear end portion 131B of the base 130. That is, the other end of the support arm 151 is connected to the rear end portion 131B of the base 130.

[0054] A protrusion 50 protrudes from the recess 21 of the lower cover 20 into the vibration space. Viewed from above, the protrusion 50 is positioned between arm portion 123B of the vibrating arm 121B and arm portion 123C of the vibrating arm 121C. The protrusion 50 extends parallel to the arms 123B and 123C in the Y-axis direction and is formed in a prism shape. The length of the protrusion 50 in the Y-axis direction is approximately 200 μm, and its length in the X-axis direction is approximately 15 μm. Furthermore, the number of protrusions 50 is not limited to one; there can be two or more. By positioning the protrusion 50 between the vibrating arms 121B and 121C and protruding from the bottom plate 22 of the recess 21, the rigidity of the lower cover 20 can be improved, and the deflection of the resonator 10 formed on the lower cover 20 and the warping of the lower cover 20 can be suppressed.

[0055] Next, refer to Figure 4 as well as Figure 5 The stacked structure and operation of the resonant device according to the first embodiment will be described. Figure 4 It is a schematic representation Figure 1 A cross-sectional view along the X-axis of the stacked structure of the resonant device 1 shown. Figure 5 It is a schematic representation Figure 1 A cross-sectional view along the Y-axis of the stacked structure of the resonant device 1 shown.

[0056] like Figure 4 as well as Figure 5 As shown, the resonant device 1 has a retaining portion 140 of the resonator 10 attached to the side wall 23 of the lower cover 20, and further attaches the retaining portion 140 of the resonator 10 to the side wall 33 of the upper cover 30. In this way, the resonator 10 is held between the lower cover 20 and the upper cover 30, and a vibration space for the resonator 110 to vibrate is formed by the lower cover 20, the upper cover 30 and the retaining portion 140 of the resonator 10.

[0057] The resonator 10, including the vibrating portion 110, the holding portion 140, and the supporting arm portion 150, is integrally formed in the same process. A metal film E1 is stacked on a Si substrate F2, which is an example of a substrate, for the resonator 10. Then, a piezoelectric film F3 is stacked on the metal film E1 to cover it, and a metal film E2 is stacked on the piezoelectric film F3. A protective film F5 is stacked on the metal film E2 to cover it. In the mass-added portions 122A to 122D, the aforementioned mass-added films 125A to 125D are further stacked on the protective film F5, respectively. The shapes of the vibrating portion 110, the holding portion 140, and the supporting arm portion 150 are formed by patterning, for example, by dry etching using an argon (Ar) ion beam to remove the laminate composed of the Si substrate F2, the metal film E1, the piezoelectric film F3, the metal film E2, and the protective film F5.

[0058] In this embodiment, an example is shown where the resonator 10 includes a metal film E1, but it is not limited thereto. For example, the resonator 10 can be made by using a low-resistance degenerate silicon substrate in the Si substrate F2, so that the Si substrate F2 itself can also serve as the metal film E1, or the metal film E1 can be omitted.

[0059] The Si substrate F2 is formed, for example, from a degenerate n-type silicon (Si) semiconductor with a thickness of about 6 μm, and may contain phosphorus (P), arsenic (As), antimony (Sb), etc., as n-type dopants. Furthermore, the resistivity of the degenerate silicon (Si) used in the Si substrate F2 is, for example, less than 1.6 mΩ·cm, more preferably less than 1.2 mΩ·cm. Moreover, a silicon oxide layer F21, such as SiO2, is formed on the lower surface of the Si substrate F2, as an example of a temperature characteristic correction layer. This improves the temperature characteristics.

[0060] In this embodiment, the silicon oxide layer F21 refers to a layer that has the function of reducing the temperature coefficient of the frequency in the vibration section 110 when a temperature correction layer is formed on the Si substrate F2, at least near room temperature, compared to the case where the silicon oxide layer F21 is not formed on the Si substrate F2. That is, the rate of change per temperature, is achieved by having the silicon oxide layer F21 in the vibration section 110. By having the silicon oxide layer F21 in the vibration section 110, for example, at the resonant frequency of the stacked structure based on the Si substrate F2, metal films E1 and E2, piezoelectric film F3, and silicon oxide layer F21, the accompanying temperature change can be reduced. The silicon oxide layer may be formed on the upper surface of the Si substrate F2, or it may be formed on both the upper and lower surfaces of the Si substrate F2.

[0061] Preferably, the silicon oxide layer F21 of the mass addition portions 122A to 122D is formed with a uniform thickness. Furthermore, uniform thickness means that the deviation of the thickness of the silicon oxide layer F21 is within ±20% of the average thickness.

[0062] Metal films E1 and E2 each include excitation electrodes for exciting vibrating arms 121A-121D and lead-out electrodes for electrically connecting the excitation electrodes to an external power source. The portions of metal films E1 and E2 that function as excitation electrodes are sandwiched between piezoelectric films F3 and opposite each other in the arm portions 123A-123D of vibrating arms 121A-121D. The portions of metal films E1 and E2 that function as lead-out electrodes are led out from the base 130 to the holding portion 140, for example, via the support arm portion 150. Metal film E1 is electrically continuous throughout the resonator 10. Metal film E2 is electrically separated in the portions formed in vibrating arms 121A and 121D and in the portions formed in vibrating arms 121B and 121C.

[0063] The thicknesses of metal films E1 and E2 are, for example, approximately 0.1 μm or more and 0.2 μm or less. After deposition, metal films E1 and E2 are patterned into excitation electrodes, lead-out electrodes, etc., by etching or other processes. Metal films E1 and E2 are formed, for example, from a metal material with a body-centered cubic crystal structure. Specifically, Mo (molybdenum) or tungsten (W) is used to form metal films E1 and E2. In this way, by using metals with a body-centered cubic crystal structure as the main component, metal films E1 and E2 can be easily made suitable for the lower and upper electrodes of the resonator 10.

[0064] The piezoelectric film F3 is a thin film formed by a piezoelectric body that converts electrical energy into mechanical energy. Based on the electric field generated by the metal films E1 and E2 in the piezoelectric film F3, the piezoelectric film F3 expands and contracts along the Y-axis in the in-plane direction of the XY plane. Through this expansion and contraction of the piezoelectric film F3, the vibrating arms 121A to 121D are displaced with their open ends toward the base plate 22 of the lower cover 20 and the base plate 32 of the upper cover 30, respectively. As a result, the resonator 10 vibrates in an out-of-plane bending vibration mode.

[0065] The thickness of the piezoelectric film F3 is, for example, about 1 μm, but it can also be about 0.2 μm to 2 μm. The piezoelectric film F3 is formed from a material with a wurtzite-type hexagonal crystal structure, and can be mainly composed of nitrides or oxides such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), calcium nitride (GaN), and indium nitride (InN). Furthermore, scandium aluminum nitride is a material in which a portion of the aluminum in aluminum nitride is replaced with scandium; alternatively, magnesium (Mg) and niobium (Nb), or magnesium (Mg) and zirconium (Zr) can be used to replace scandium. In this way, by using a piezoelectric material with a wurtzite-type hexagonal crystal structure as the main component, a piezoelectric film F3 suitable for the resonator 10 can be easily realized.

[0066] The protective film F5 protects the metal film E2 from oxidation. Furthermore, since the protective film F5 is only disposed on the side of the upper cover 30, it need not be exposed relative to the bottom plate 32 of the upper cover 30. For example, a parasitic capacitance reducing film that reduces the capacitance of the wiring formed on the resonator 10 can be formed as the protective film F5. The protective film F5 can be formed from insulating films such as silicon nitride (SiN), silicon oxide (SiO2), aluminum oxide (Al2O3), and tantalum pentoxide (Ta2O5), in addition to piezoelectric films such as aluminum nitride (AlN), scandium aluminum nitride (ScAlN), zinc oxide (ZnO), calcium nitride (GaN), and indium nitride (InN). The thickness of the protective film F5 is formed to a length less than half the thickness of the piezoelectric film F3; in this embodiment, it is, for example, about 0.2 μm. More preferably, the thickness of the protective film F5 is about one-quarter the thickness of the piezoelectric film F3. Furthermore, when forming the protective film F5 using a piezoelectric material such as aluminum nitride (AlN), it is preferable to use a piezoelectric material having the same orientation as the piezoelectric film F3.

[0067] The protective film F5 for the mass additions 122A to 122D is preferably formed with a uniform thickness. Furthermore, uniform thickness means that the thickness deviation of the protective film F5 is within ±20% of the average thickness.

[0068] The mass-adding films 125A to 125D constitute the surface of the upper cover 30 side of each of the mass-adding parts 122A to 122D, and correspond to the frequency adjustment films of each of the vibrating arms 121A to 121D. The resonant frequency of the resonator 10 is adjusted by trimming a portion of each of the mass-adding films 125A to 125D. From the perspective of frequency adjustment efficiency, it is preferable that the mass-adding films 125A to 125D are formed of a material whose etching mass reduction rate is faster than that of the protective film F5. The mass reduction rate is expressed as the product of the etching rate and density. The etching rate refers to the thickness removed per unit time. The magnitude relationship between the etching rates of the protective film F5 and the mass-adding films 125A to 125D is arbitrary as long as the relationship between their mass reduction rates is as described above. Furthermore, from the viewpoint of efficiently increasing the weight of the mass-adding parts 122A to 122D, it is preferable that the mass-adding films 125A to 125D are formed of a material with a higher specific gravity. For these reasons, for example, mass-added films 125A to 125D are formed from metallic materials such as molybdenum (Mo), tungsten (W), gold (Au), platinum (Pt), nickel (Ni), aluminum (Al), and titanium (Ti).

[0069] In the frequency adjustment process, a portion of the upper surface of each of the mass-added films 125A to 125D is removed by a trimming process. For example, the trimming process of the mass-added films 125A to 125D can be performed by dry etching irradiated with an argon (Ar) ion beam. The ion beam can irradiate a wide area, resulting in excellent processing efficiency, but there is a concern that the mass-added films 125A to 125D may become charged due to their electric charge. In order to prevent changes in the vibration trajectory of the vibrating arms 121A to 121D caused by the charging of the mass-added films 125A to 125D, and the resulting degradation of the vibration characteristics of the resonator 10, it is preferable to ground the mass-added films 125A to 125D.

[0070] Lead wires C1, C2, and C3 are formed on the protective film F5 of the holding part 140. Lead wire C1 is electrically connected to the metal film E1 through a through-hole formed in the piezoelectric film F3 and the protective film F5. Lead wire C2 is electrically connected to the portion of the metal film E2 formed in the vibrating arms 121A and 121D through a through-hole formed in the protective film F5. Lead wire C3 is electrically connected to the portion of the metal film E2 formed in the vibrating arms 121B and 121C through a through-hole formed in the protective film F5. Lead wires C1 to C3 are formed of metallic materials such as aluminum (Al), germanium (Ge), gold (Au), and tin (Sn).

[0071] In this embodiment, Figure 4 The diagram shows an example where the arms 123A-123D, leads C2 and C3, and through electrodes V2 and V3 are located on the same plane, but they are not necessarily located on the same plane. For example, through electrodes V2 and V3 may also be formed at a position that is parallel to the ZX plane defined by the Z-axis and cuts off the cross-section of arms 123A-123D and moves away from the Y-axis direction.

[0072] Similarly, in this embodiment, although in Figure 5 The example shown is a cross-section in which the mass attachment 122A, arm 123A, leads C1, C2, and through electrodes V1, V2 are located on the same plane, but they are not necessarily located on the same plane.

[0073] The bottom plate 22 and sidewall 23 of the lower cover 20 are integrally formed on a Si substrate P10. The Si substrate P10 is formed of undegenerate silicon, and its resistivity is, for example, 10 Ω·cm or higher. The Si substrate P10 is exposed inside the recess 21 of the lower cover 20. A silicon oxide layer F21 is formed on the upper surface of the protrusion 50. However, from the viewpoint of suppressing the charging of the protrusion 50, a Si substrate P10 with a lower resistivity than the silicon oxide layer F21 can also be exposed on the upper surface of the protrusion 50, and a conductive layer can also be formed there.

[0074] The thickness of the lower cover 20 in the Z-axis direction is specified to be about 150 μm, and similarly, the depth of the recess 21 is specified to be about 50 μm.

[0075] The bottom plate 32 and sidewall 33 of the top cover 30 are integrally formed on a Si substrate Q10. Preferably, the surface, back surface, and inner surface of the through holes of the top cover 30 are covered with a silicon oxide film Q11. The silicon oxide film Q11 is formed on the surface of the Si substrate Q10, for example, by oxidation of the Si substrate Q10 or by chemical vapor deposition (CVD). The Si substrate Q10 is exposed inside the recess 31 of the top cover 30. In addition, a gas-absorbing layer may be formed on the side of the recess 31 of the top cover 30 opposite to the resonator 10. The gas-absorbing layer is formed, for example, of titanium (Ti), and adsorbs the exhaust gas released from the joint 40, etc., described later, to suppress the decrease of the vacuum level of the vibration space. In addition, the air-absorbing layer can also be formed on the side of the recess 21 of the lower cover 20 opposite to the resonator 10, or on the side of the recess 21 of the lower cover 20 and the recess 31 of the upper cover 30 opposite to the resonator 10.

[0076] The thickness of the top cover 30 in the Z-axis direction is specified to be about 150 μm, and similarly, the depth of the recess 31 is specified to be about 50 μm.

[0077] Terminals T1, T2, and T3 are formed on the upper surface of the cover 30 (the side opposite to the resonator 10). Terminal T1 is a mounting terminal for grounding the metal film E1. Terminal T2 is a mounting terminal for electrically connecting the metal films E2 of the vibrating arms 121A and 121D to an external power supply. Terminal T3 is a mounting terminal for electrically connecting the metal films E2 of the vibrating arms 121B and 121C to an external power supply. For example, terminals T1 to T3 are formed by electroplating a metallization layer (base layer) of chromium (Cr), tungsten (W), nickel (Ni), etc., with nickel (Ni), gold (Au), silver (Ag), Cu (copper), etc. Alternatively, dummy terminals electrically insulated from the resonator 10 can be formed on the upper surface of the cover 30 for the purpose of adjusting parasitic capacitance and balancing mechanical strength.

[0078] Through electrodes V1, V2, and V3 are formed inside the side wall 33 of the upper cover 30. Through electrode V1 electrically connects terminal T1 to lead C1, through electrode V2 electrically connects terminal T2 to lead C2, and through electrode V3 electrically connects terminal T3 to lead C3. Through electrodes V1 to V3 are formed by filling conductive material into through holes in the side wall 33 of the upper cover 30 in the Z-axis direction. The conductive material used for filling is, for example, polysilicon (Poly-Si), copper (Cu), or gold (Au).

[0079] A joining portion 40 is formed between the sidewall 33 of the upper cover 30 and the retaining portion 140, through which the upper cover 30 is joined to the resonator 10. The joining portion 40 is formed in a closed ring shape surrounding the vibrating portion 110 in the XY plane, thereby hermetically sealing the vibration space of the resonator 10 in a vacuum state. The joining portion 40 is formed, for example, from a metal film in which aluminum (Al) film, germanium (Ge) film, and aluminum (Al) film are sequentially stacked and eutectic bonded. In addition, the joining portion 40 can also be formed by a combination of films appropriately selected from gold (Au), tin (Sn), copper (Cu), titanium (Ti), silicon (Si), etc. In addition, in order to improve the adhesion, the joining portion 40 can also contain metal compounds such as titanium nitride (TiN) and tantalum nitride (TaN) between the films.

[0080] In this embodiment, terminal T1 is grounded, and alternating voltages with opposite phases are applied to terminals T2 and T3. Therefore, the phase of the electric field formed by the piezoelectric film F3 in vibrating arms 121A and 121D is opposite to the phase of the electric field formed by the piezoelectric film F3 in vibrating arms 121B and 121C. Consequently, the outer vibrating arms 121A and 121D and the inner vibrating arms 121B and 121C are displaced in opposite directions.

[0081] For example, such as Figure 4 As shown, when the mass attachments 122A, 122D and arms 123A, 123D of each of the vibrating arms 121A and 121D are displaced toward the inner surface of the upper cover 30, the mass attachments 122B, 122C and arms 123B, 123C of each of the vibrating arms 121B and 121C are displaced toward the inner surface of the lower cover 20. Conversely, although not shown in the figure, when the mass attachments 122A, 122D and arms 123A, 123D of each of the vibrating arms 121A and 121D are displaced toward the inner surface of the lower cover 20, the mass attachments 122B, 122C and arms 123B, 123C of each of the vibrating arms 121B and 121C are displaced toward the inner surface of the upper cover 30. Thus, at least two of the four vibrating arms 121A to 121D undergo out-of-plane bending at different phases.

[0082] Thus, between adjacent vibrating arms 121A and 121B, vibrating arms 121A and 121B vibrate in opposite directions up and down about a central axis r1 extending in the Y-axis direction. Similarly, between adjacent vibrating arms 121C and 121D, vibrating arms 121C and 121D vibrate in opposite directions up and down about a central axis r2 extending in the Y-axis direction. This generates torsional moments in opposite directions on the central axes r1 and r2, producing bending vibrations in the vibrating section 110. The maximum amplitude of vibrating arms 121A to 121D is approximately 50 μm, and the amplitude during normal operation is approximately 10 μm.

[0083] In addition to adjusting the resonant frequency based on the aforementioned trimming process, the resonator 10 also undergoes a frequency adjustment process involving fine-tuning the resonant frequency through overexcitation. In this frequency adjustment process, firstly, the resonant frequency is measured while a predetermined driving voltage is applied to the resonator 10. If the measured resonant frequency does not meet the desired value, a voltage greater than the predetermined driving voltage is applied to the resonator 10, causing the vibrating arm 121 to be overexcited. In this frequency adjustment process, the power supplied to the resonator 10 is, for example, 0.2 μW or more. Furthermore, overexcitation refers to causing the resonator 10 to vibrate with an amplitude more than ten times its normal amplitude; specifically, the amplitude during overexcitation is 50 μm or more.

[0084] By over-exciting the vibrating arm 121, the mass-added films 125A to 125D in the vibrating arm 121 collide with at least one of the bottom plate 32 or the suction layer of the upper cover 30, and the bottom plate 22 of the lower cover 20. The bottom plate 32 or the suction layer of the upper cover 30 is formed of a material with a higher hardness than the mass-added films 125A to 125D. Therefore, the mass-added films 125A to 125D are sheared off due to the collision with the bottom plate 32 or the suction layer, thus reducing the mass of the vibrating arm 121. Similarly, at least one of the Si substrate F2 and the silicon oxide layer F21 formed on the lower cover 20 side (back side) of the vibrating arm 121 has a lower hardness than the bottom plate 22. Therefore, the Si substrate F2 or the silicon oxide layer F21 is also sheared off on the back side of the vibrating arm 121, thereby reducing the mass of the vibrating arm 121. In this way, by reducing the mass of the vibrating arm 121, the resonant frequency of the resonator 10 increases.

[0085] After over-exciting the resonator 10 to cause the vibrating arm 121 to collide with at least one of the upper cover 30 and the lower cover 20, a predetermined driving voltage is applied to the resonator 10 again, and the resonant frequency is measured. By repeatedly measuring the resonant frequency with a predetermined driving voltage applied to the resonator 10 and over-exciting the resonator 10 with a voltage greater than the driving voltage, until the measured resonant frequency reaches the desired value, the resonant frequency of the resonator 10 is adjusted to an appropriate value.

[0086] In this way, the resonant frequency of the resonator 10 can be adjusted even after encapsulation by the lower cover 20 and the upper cover 30 based on the overexcitation frequency adjustment process. In addition, since no processing steps apply thermal or stress loads after the frequency adjustment process, the variation of the resonant frequency can be suppressed. Furthermore, since the adjustment can be performed at the same time as the resonant frequency is measured, it has the advantage of easily obtaining the desired resonant frequency.

[0087] However, some resonator components, designed to improve DLD (Dissonance Detection and Resonance), have asymmetrical structures, such as the support arm, when viewed from above. In this case, during the frequency adjustment process based on overexcitation, the multiple vibrating arms supported by the support arm may not vibrate horizontally relative to the upper and lower covers. Therefore, when the vibrating arms are overexcited to collide with at least one of the upper and lower covers, deviations may occur in the cutting amounts of the multiple vibrating arms, such as the outer arms having a larger cutting amount and the inner arms having a smaller cutting amount. As a result, the adjustment time to obtain the desired resonant frequency becomes longer; in other words, there is a concern that the resonant frequency adjustment rate may decrease.

[0088] In contrast, the inventors of this invention have discovered that when the support arm is connected to the base at a specified position and the length of the support arm is within a specified range, it is possible to simultaneously improve the DLD and suppress the reduction in adjustment rate.

[0089] Next, refer to Figure 6 The dimensions of the vibrating part when viewed from above are explained. Figure 6 It is used for explanation Figure 3 A top view showing the dimensions of the resonator 10. Furthermore, in Figure 6 For the sake of simplicity, a portion of the harmonic oscillator 10 is shown in the diagram.

[0090] like Figure 6 As shown, in the resonator 10 of this embodiment, the length (i.e., width WG) of each of the mass additions 122A to 122D along the X-axis is, for example, 49 μm. Furthermore, the length (i.e., the width WA) of each of the vibrating arms 121A to 121D along the X-axis is, for example, 26 μm, and the length (i.e., the length LA) of each of the vibrating arms 121A to 121D along the Y-axis is, for example, 410 μm.

[0091] Furthermore, in the base 130, the length from the front end 131A to the rear end 131B, i.e., the base length LB, is, for example, 25 μm. On the other hand, the length from the left end 131C to the right end 131D, i.e., the base width WB, is, for example, 176 μm.

[0092] In addition, the width of the support arm 151, specifically the length of the support arm 153 along the X-axis direction, i.e., the support arm width WS is, for example, 20 μm, and the length of the support arm 151, specifically the length of the support arm 153 along the Y-axis direction, i.e., the support arm length LS is, for example, 125 μm.

[0093] The other end of the support arm 151, specifically the other end of the support rear arm 152, is located in the rear end portion 131B of the base 130, at a position offset 10 μm to the left in the negative X-axis direction, with the position through which the center line CL1 passes as a reference. In the following description, unless otherwise explicitly stated, the position through which the center line CL1 passes in the rear end portion 131B of the base 130 is represented as the origin (zero), one side (right side) is represented as "+" (positive), and the other side (left side) is represented as "-" (negative). That is, in Figure 6 In the example shown, the other end of the support arm 152 is connected to a position 10 μm away from the center line CL1 in the rear end portion 131B of the base 130.

[0094] In addition, unless otherwise specified, the dimensions of each part in the following description are for use only. Figure 6 The length has been explained.

[0095] Next, refer to Figure 7 as well as Figure 8 The connection position of the support arm on the base and the relationship between the support arm length and the DLD are explained. Figure 7 It is a graph showing the relationship between the length LS of each support arm 151, the connection position of the support arm 151 on the base 130, and the frequency change rate per unit power. Figure 8 This is a diagram showing the relationship between the support arm length LS of support arm 151 and the connection position of support arm 151 on base 130. Figure 7 In the diagram, the horizontal axis represents the connection position of the support arm 151 when the position through which the center line CL1 passes in the rear end 131B of the base 130 is set to zero, one side (right side) of the center line CL1 is set to positive, and the other side (left side) of the center line CL1 is set to negative. The vertical axis represents the rate of change (df / f) of the resonant frequency (f) per unit power (0.2 μW), which is an indicator of the DLD. Figure 7 The lines in the diagram represent the support arm lengths LS of support arm 151 when they are 225 μm, 125 μm, and 75 μm, respectively. Figure 8 In the diagram, the horizontal axis represents the support arm length LS of the support arm 151, and the vertical axis represents the connection position of the support arm 151 when the position through which the center line CL1 in the rear end 131B of the base 130 passes is set to zero, one side (right side) of the center line CL1 is set to positive, and the other side (left side) of the center line CL1 is set to negative.

[0096] like Figure 7As shown, for all support arm lengths LS, the frequency variation rate per unit power can be made zero or approximately zero by adjusting the connection position of the support arm 151. Specifically, the frequency variation rate per unit power is made zero or approximately zero when the support arm length LS of the support arm 151 is 225 μm and the connection position of the support arm 151 is 51.5 μm, when the support arm length LS of the support arm 151 is 125 μm and the connection position of the support arm 151 is -10 μm, and when the support arm length LS of the support arm 151 is 75 μm and the connection position of the support arm 151 is -20 μm.

[0097] Based on these combinations, the connection position between the support arm length LS and the support arm 151 is as follows: Figure 8 When the relationship between the lines shown by the dashed lines is considered, the DLD of the resonator 10 can be improved.

[0098] Next, refer to Figures 9-11 The displacement based on the vibration of the vibrating arm is explained. Figure 9 This is a cross-sectional view schematically showing the displacement of the vibrating arms 121A to 121D when the connection position of the support arm 151 is -10μm. Figure 10 This is a cross-sectional view schematically showing the displacement of the vibrating arms 121A to 121D when the connection position of the support arm 151 is -50μm. Figure 11 This is a graph showing the relationship between the connection position of the support arm 151 on the base 130 and the displacement of the vibrating arms 121A to 121D. Furthermore, in Figure 9 as well as Figure 10 In the vibrating arms 121A to 121D shown, the darker colored areas represent larger displacements, and the lighter colored areas represent smaller displacements. Figure 11 In the diagram, the horizontal axis represents the connection position of the support arm 151 when the position through which the center line CL1 passes in the rear end 131B of the base 130 is set to zero, one side (right side) of the center line CL1 is set to positive, and the other side (left side) of the center line CL1 is set to negative. The vertical axis represents the ratio (%) of the maximum displacement of the vibrating arms 121A to 121D when the maximum displacement of the vibrating arms in an imaginary resonator symmetrical about the support arm with respect to the center line is set as a reference (100%).

[0099] When the vibrating arm 121 vibrates in an out-of-plane bending vibration mode, each vibrating arm 121A to 121D mainly displaces in the Z-axis direction. Specifically, as follows: Figure 9 as well as Figure 10 As shown on the left, when vibrating arms 121A and 121D are displaced in the negative Z-axis direction, vibrating arms 121B and 121C are displaced in the positive Z-axis direction. Conversely, as... Figure 9 as well as Figure 10 As shown on the right, when vibrating arms 121A and 121D are displaced in the positive Z-axis direction, vibrating arms 121B and 121C are displaced in the negative Z-axis direction. Furthermore, according to... Figure 9 as well as Figure 10 It can be seen that the displacement of vibrating arm 121A and vibrating arm 121D, or vibrating arm 121B and vibrating arm 121C, is the largest when they are displaced in the negative Z-axis direction.

[0100] like Figure 11 As shown, the maximum displacement of vibrating arms 121A and 121D varies relatively little with respect to the connection position of support arm 151, ranging from 95% to 100% within the range of -50μm to 50μm from the connection position of support arm 151. Furthermore, the maximum displacement of vibrating arms 121A and 121D is closest to 100% when the connection position of support arm 151 is -50μm. On the other hand, the maximum displacement of vibrating arms 121B and 121C varies relatively significantly with respect to the connection position of support arm 151, ranging from 110% to 85% within the range of -50μm to 50μm from the connection position of support arm 151. Furthermore, the maximum displacement of vibrating arms 121B and 121C is closest to 100% when the connection position of support arm 151 is near -5μm.

[0101] Next, refer to Figure 12 as well as Figure 13 The adjustment rate based on the overexcitation resonant frequency is explained. Figure 12 It is a graph showing the relationship between the adjustment time and the rate of change of the resonant frequency based on the overexcitation resonant frequency for each support arm length LS of support arm 151 and each connection position of support arm 151. Figure 13 This is a graph showing the relationship between the connection position of the support arm 151 on the base 130 and the adjustment rate based on the overexcited resonant frequency. Figure 12 In the diagram, the horizontal axis represents the settling time based on the overexcited resonant frequency (f), and the vertical axis represents the rate of change of the resonant frequency (df / f). Additionally, Figure 12 The lines in the diagram represent the following scenarios: the support arm 151 has a length LS of 125 μm and a connection point of 0 μm; the support arm 151 has a length LS of 125 μm and a connection point of -5 μm; the support arm 151 has a length LS of 125 μm and a connection point of -10 μm; the support arm 151 has a length LS of 75 μm and a connection point of -20 μm; and the support arm 151 has a length LS of 225 μm and a connection point of 51 μm. Figure 13 In the diagram, the horizontal axis represents the connection position of the support arm 151 when the position through which the center line CL1 passes in the rear end 131B of the base 130 is set to zero, one side (right side) of the center line CL1 is set to positive, and the other side (left side) of the center line CL1 is set to negative. The vertical axis represents the rate of change (df / f) of the resonant frequency (f) per unit adjustment time (1 min).

[0102] like Figure 12 As shown, it can be seen that when the support arm length LS of support arm 151 is 75 μm and the connection position of support arm 151 is -20 μm, and when the support arm length LS of support arm 151 is 225 μm and the connection position of support arm 151 is 51 μm, the frequency change rate based on the overexcitation resonant frequency is relatively low. This is considered to be a result of the deviation in the displacement of the vibration in the multiple vibrating arms 121A to 121D, i.e., a decrease in the resonant frequency adjustment rate.

[0103] In contrast, it can be seen that when the support arm length LS of support arm 151 is 125μm and the connection position of support arm 151 is 0μm, when the support arm length LS of support arm 151 is 125μm and the connection position of support arm 151 is -5μm, and when the support arm length LS of support arm 151 is 125μm and the connection position of support arm 151 is -10μm, the frequency change rate based on the overexcitation resonant frequency is relatively high. This is because each vibrating arm 121A to 121D has approximately the maximum displacement and vibrates at approximately the same rate, which can suppress the decrease in the resonant frequency adjustment rate.

[0104] As an example, the effective range for adjusting the resonant frequency based on overexcitation is set to a frequency adjustment rate of 30 ppm / min or higher. In this case, Figure 12 In the example shown, when the support arm length LS of the support arm 151 is 125 μm, the effective range of the resonant frequency based on overexcitation is satisfied.

[0105] With the support arm length LS of support arm 151 being 125 μm, the connection position and adjustment rate of support arm 151 become... Figure 13 The relationship is parabolic, as shown by the dashed line. Figure 13 The dashed line shown is an approximate quadratic curve (quadratic function) based on a graph depicting the adjustment rate as the connection position of the support arm 151 changes. From the intersection of this quadratic curve (quadratic function) and the adjustment rate of 30 ppm / min, as the range where the frequency adjustment rate is above 30 ppm / min, it can be deduced that the connection position of the support arm 151 is above -18.4 μm and below 4.8 μm.

[0106] In other words, for frequency adjustment rates above 30 ppm / min, the connection position of the support arm 151 can be above -0.105 WB and below 0.0027 WB relative to the base width WB of the base 130, which is 176 μm in one example.

[0107] Therefore, in the resonator 10 of this embodiment, when viewed from above, the other end of the support arm 151 is connected to a position that, with reference to the position through which the center line CL1 in the rear end portion 131B of the base 130 passes, is within a range of -0.1WB to 0.1WB relative to the base width WB of the base 130.

[0108] Here, refer to Figure 14 The relationship between the effective range of the overexcitation-based resonant frequency adjustment and the improvement of DLD is explained. Figure 14 This is a diagram showing the relationship between the support arm length LS of support arm 151 and the connection position of support arm 15 on base 130. Figure 14 In the diagram, the horizontal axis represents the support arm length LS of the support arm 151, and the vertical axis represents the connection position of the support arm 151 when the position through which the center line CL1 in the rear end 131B of the base 130 passes is set to zero, one side (right side) of the center line CL1 is set to positive, and the other side (left side) of the center line CL1 is set to negative.

[0109] Figure 14 The dotted lines shown are Figure 8 The dashed lines are the same, representing the combination of the support arm length LS of support arm 151 and the connection position of support arm 151, which can improve the DLD of resonator 10. Figure 14 In the middle, if the application is based on the above... Figure 13 The chart shows that the connection position of the support arm 151 is in the range of -18.4μm to 4.8μm, and the support arm length LS of the support arm 151 can be derived to be in the range of 88.8μm to 158.7μm.

[0110] In other words, for a frequency adjustment rate of 30 ppm / min or higher and capable of improving the DLD of the resonator 10, the support arm length LS of the support arm 151 can be greater than 0.217LA and less than 0.387LA relative to the vibration arm length LA of the vibration arm 121, which is 410 μm in one example.

[0111] Therefore, in the resonator 10 of this embodiment, the support arm length LS of the support arm 151 is more than 0.2 times and less than 0.4 times the vibration arm length LA of the vibration arm 121.

[0112] Thus, when viewed from above, with the other end of the support arm 151 connected to a position where the centerline CL1 of the rear end 131B of the base 130 passes through, the position relative to the base width WB ranges from -0.1WB to 0.1WB, where the base width WB is the length of the base 130 in the direction orthogonal to the centerline CL1. Furthermore, the length of the support arm 151 in the direction parallel to the long side of the vibrating section 110, i.e., the support arm length LS, is more than 0.2 times and less than 0.4 times the length of the vibrating arm 121 in the long side direction, i.e., the vibrating arm length LA. Therefore, compared to conventional resonators that are symmetrical or approximately symmetrical about the centerline of the long side of the vibrating section, the deflection of the base 130 can be increased. Additionally, each of the vibrating arms 121A to 121D can vibrate approximately with the maximum displacement, and when adjusting the resonant frequency based on overexcitation, deviations in frequency variation among the multiple vibrating arms 121A to 121D can be suppressed. As a result, it is possible to simultaneously achieve the desired adjustment rate within an effective range during the overexcitation process for adjusting the resonant frequency, and to reduce the rate of frequency change per unit power of the resonant frequency, which is a key performance indicator (DLD). Therefore, DLD can be improved, and the reduction in the adjustment rate of the resonant frequency can be suppressed.

[0113] Furthermore, the support arm 151 includes a support side arm 153 extending in a direction parallel to the long side of the vibration unit 110. Therefore, it is easy to achieve a support arm 151 whose support arm length LS is 0.2 to 0.4 times that of the vibration arm length LA of the vibration arm 121.

[0114] Additionally, the support arm 151 also includes a rear support arm 152, one end of which is connected to the support side arm 153, and the other end of which is connected to the rear end portion 131B of the base 130. Thus, it is possible to easily implement a support arm 151 with its other end connected to a position ranging from -0.1WB to 0.1WB, relative to the length of the base 130 in a direction orthogonal to the center line CL1 (i.e., the base width WB), when the position through which the center line CL1 of the rear end portion 131B of the base 130 passes as a reference.

[0115] Here, the inventors of this invention have discovered that when the ratio of the base length LB of the base 130 to the base width WB of the base 130 is less than a predetermined multiple, the frequency variation rate of the resonant frequency per unit power can be reduced. More specifically, it has been found that it is preferable for the base length LB of the base 130 to the base width WB of the base 130 to be less than 0.3 times. Therefore, the frequency variation rate of the resonant frequency per unit power can be effectively reduced.

[0116] Specifically, in the miniaturized resonator 10, the base length LB of the base 130 is less than 90 μm, and the base width WB of the base 130 is less than 300 μm. Thus, even in the miniaturized resonator 10 with its limited size, the rate of change of the resonant frequency per unit power can be effectively reduced.

[0117] Although this embodiment uses an example where the resonator 10's vibration section 110 includes four vibration arms 121A to 121D, it is not limited to this. The vibration section 110 may also include three or more vibration arms, for example. In this case, at least two vibration arms bend out of plane at different phases.

[0118] Furthermore, although this embodiment uses an example where one end of the support arm 151 of the resonator 10 is connected to the frame 141D of the holding portion 140, it is not limited to this. For example, one end of the support arm 151 may also be connected to the frame 141C of the holding portion 140.

[0119] The exemplary embodiments of the present invention have been described above. In the resonator according to one embodiment, when viewed from above, the other end of the support arm is connected to a position where the center line of the rear end of the base passes through, with reference to the position. This position is within the range of -0.1WB to 0.1WB relative to the base width WB, where the base width WB is the length of the base in the direction orthogonal to the center line. Furthermore, the length of the support arm in the direction parallel to the long side of the vibrating part, i.e., the length of the support arm relative to the long side of the vibrating arm, i.e., the length of the vibrating arm, is more than 0.2 times and less than 0.4 times. Therefore, compared to conventional resonators that are symmetrical or approximately symmetrical about the center line of the long side of the vibrating part, the deflection of the base can be increased. In addition, each vibrating arm can vibrate approximately with its maximum displacement, and when adjusting the resonant frequency based on overexcitation, deviations in the frequency changes of multiple vibrating arms can be suppressed. As a result, it is possible to simultaneously achieve an effective adjustment rate within the range during the process of adjusting the resonant frequency through overexcitation and reduce the frequency change rate of the resonant frequency per unit power, which is a DLD (Dissonance Limiting Parameter). Therefore, it is possible to improve DLD and suppress the decrease in the resonant frequency adjustment rate.

[0120] Furthermore, in the resonator according to one embodiment, the support arm includes a support side arm extending in a direction parallel to the long side direction of the vibrating part. Therefore, it is easy to achieve a support arm whose length is at least 0.2 times and less than 0.4 times the length of the vibrating arm relative to the length of the vibrating arm.

[0121] Furthermore, in the resonator according to one embodiment, the support arm further includes a support rear arm, one end of which is connected to the support side arm and the other end of which is connected to the rear end of the base. Thus, it is easy to realize a support arm that, when using the position through which the centerline of the rear end of the base passes as a reference, is connected at one end to a position ranging from -0.1WB to 0.1WB in the direction orthogonal to the centerline of the base (i.e., the base width WB).

[0122] Furthermore, in the resonator according to one embodiment, the length from one end of the base to the other end, i.e., the base length relative to the base width, is 0.3 times or less. Here, the inventors of the present invention have discovered that when the ratio of the base length to the base width is less than a predetermined multiple, more specifically less than 0.3 times, the frequency variation rate of the resonant frequency per unit power can be reduced. Therefore, the frequency variation rate of the resonant frequency per unit power can be effectively reduced.

[0123] Furthermore, in the resonator according to one embodiment, the base length is less than 90 μm and the base width is less than 300 μm. Therefore, even in a resonator whose size is limited by miniaturization, the rate of change of the resonant frequency per unit power can be effectively reduced.

[0124] Furthermore, the resonant device according to one embodiment includes the aforementioned resonator. Therefore, a resonant device that can easily improve DLD while suppressing the decrease in the resonant frequency adjustment rate can be realized.

[0125] Furthermore, the aforementioned resonant device also includes a lower cover and an upper cover. This allows for the easy formation of a vibration space for an out-of-plane bending vibration section.

[0126] Furthermore, the embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit the scope of the invention. The present invention can be modified / improved without departing from its spirit, and equivalents are also included in the present invention. That is, as long as the features of the present invention are present, embodiments with appropriate design changes made by those skilled in the art to the embodiments and / or modifications are also included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, and dimensions of the embodiments and / or modifications are not limited to the illustrated content and can be appropriately modified. In addition, the embodiments and modifications are illustrative; of course, partial substitutions or combinations of the structures shown in different embodiments and / or modifications are possible, and these embodiments are also included within the scope of the present invention as long as they contain the features of the present invention.

[0127] Explanation of reference numerals in the attached figures

[0128] 1…Resonant device, 10…Resonator, 20…Lower cover, 21…Recess, 22…Base plate, 23…Side wall, 30…Upper cover, 31…Recess, 32…Base plate, 33…Side wall, 40…Joint, 50…Protrusion, 110…Vibrating part, 120…Excitation part, 121, 121A, 121B, 121C, 121D…Vibrating arms, 122A, 122B, 122C, 122D…Mass attachment, 123A, 123B, 123C, 123D…Arm, 125A, 125B, 125C… 125D…Mass-added membrane, 130…Base, 131A…Front end, 131B…Rear end, 131C…Left end, 131D…Right end, 140…Holding part, 141A, 141B, 141C, 141D…Frame, 151…Support arm, 152…Support rear arm, 153…Support side arm, CL1…Centerline, LA…Vibration arm length, LB…Base length, LS…Support arm length, r1, r2…Center axis, WA…Vibration arm width, WB…Base width, WG…Width, WS…Support arm width.

Claims

1. A harmonic oscillator, possessing: The vibrating part includes multiple vibrating arms and a base. The multiple vibrating arms are three or more vibrating arms, each having a fixed end. At least two vibrating arms are bent out of plane at different phases. The base has one end connected to the fixed end of each of the multiple vibrating arms and another end opposite to that fixed end. The retaining part is configured to retain the aforementioned vibrating part; and A support arm, one end of which is connected to the aforementioned retaining portion, and the other end of which is connected to the aforementioned other end of the base. When viewed from above, the other end of the aforementioned support arm is connected to a position relative to the base width WB, ranging from -0.1WB to 0.1WB, with the position where the center line of the vibrating part in the other end of the aforementioned base passes through as a reference. The base width WB is the length of the base in a direction orthogonal to the center line. The length of the support arm in the direction parallel to the long side of the vibrating part is more than 0.2 times and less than 0.4 times the length of the long side of the vibrating arm.

2. The harmonic oscillator according to claim 1, wherein, The aforementioned support arm includes a support side arm that extends in a direction parallel to the long side of the aforementioned vibrating part.

3. The harmonic oscillator according to claim 2, wherein, The aforementioned support arm also includes a rear support arm, one end of which is connected to the aforementioned side support arm, and the other end of which is connected to the aforementioned other end of the aforementioned base.

4. The harmonic oscillator according to any one of claims 1 to 3, wherein, The length of the base from one end to the other end, i.e. the base length, is less than 0.3 times the width of the base.

5. The harmonic oscillator according to claim 4, wherein, The base length is less than 90 μm and the base width is less than 300 μm.

6. A resonant device, wherein, It has a harmonic oscillator as described in any one of claims 1 to 5.

7. The resonant device according to claim 6, wherein, It also has a cover.

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