Resonant device

Abstract

The present invention relates to a resonant device. The present invention provides a resonant device including: a lower cover having a concave portion; and a resonator mounted on the lower cover and having a vibrating arm and a holding portion. The vibrating arm can perform out-of-plane bending vibration in a space including the concave portion. The holding portion is provided around the vibrating arm and has an opposing portion opposing the end portion of the vibrating arm. The opposing portion of the holding portion is located outside the resonator with respect to a straight line that connects the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the concave portion of the lower cover and the concave portion of the lower cover, and the opening edge of the concave portion on the end portion side of the vibrating arm.

Description

Technical Field

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

[0002] As a device for realizing a timing function in an electronic device, a resonator such as a piezoelectric oscillator is used. With the miniaturization of electronic devices, resonators are also required to be miniaturized, and resonators manufactured using MEMS (Micro Electro Mechanical Systems) technology (hereinafter, also referred to as "MEMS oscillators") have attracted attention.

[0003] For example, Patent Document 1 describes the following structure: By over-exciting the vibrating arm, the adjustment film on the vibrating arm collides with at least one of the bottom plate of the upper cover and the bottom plate of the lower cover to shave off the adjustment film, thereby reducing the weight of the vibrating arm and adjusting the resonance frequency of the resonator.

[0004] Patent Document 1: International Publication No. 2017 / 212677

[0005] However, in the prior art, when the vibrating arm is over-excited, there is a concern that insulation failure may occur if the adjustment film scattered from the vibrating arm scatters into the gap between the upper cover and the resonator or the inner wall of the resonator.

[0006] In addition, such a problem is not limited to the case where the vibrating arm is over-excited, and the same problem also occurs when trimming the adjustment film using an ion beam or the like to adjust the resonance frequency of the vibrating arm for a resonator joined to the lower cover. Summary of the Invention

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a resonant device that can suppress insulation failure caused by scattered matter from a vibrating arm when adjusting the resonance frequency of the vibrating arm.

[0008] A resonant device according to one aspect of the present invention includes: a lower cover having a first concave portion; and a resonator mounted on the lower cover and having a vibrating arm and a holding portion, the vibrating arm being capable of performing out-of-plane bending vibration in a space including the first concave portion, the holding portion being provided around the vibrating arm and having an opposing portion opposing the end portion of the vibrating arm, and the opposing portion of the holding portion being located outside the resonator with respect to a straight line connecting an intersection point of a perpendicular line extending from the end portion of the vibrating arm toward the first concave portion of the lower cover and the first concave portion of the lower cover and an opening edge of the first concave portion on the end portion side of the vibrating arm.

[0009] According to the present invention, when adjusting the resonance frequency of the vibrating arm, it is possible to suppress insulation failure caused by flying objects from the vibrating arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a perspective view schematically showing the appearance of a resonator according to a first embodiment of the present invention.

[0011] Figure 2 FIG. 2 is an exploded perspective view schematically showing the structure of a resonator according to a first embodiment of the present invention.

[0012] Figure 3 FIG. 3 is a top view of a resonator according to a first embodiment of the present invention with the upper substrate removed.

[0013] Figure 4 FIG. 4 is a sectional view taken along line AA' of Figure 1 .

[0014] Figure 5 FIG. 5 is a diagram for explaining an example of a method for adjusting the frequency of the resonator.

[0015] Figure 6 FIG. 6 is a diagram schematically showing the main part of a resonator according to a first embodiment of the present invention.

[0016] Figure 7 FIG. 7 is a diagram for explaining the function of a resonator according to a first embodiment of the present invention.

[0017] Figure 8 FIG. 8 is a diagram schematically showing the main part of a resonator according to a second embodiment of the present invention.

[0018] Figure 9 FIG. 9 is a diagram for explaining the function of a resonator according to a second embodiment of the present invention.

[0019] Figure 10 FIG. 10 is a diagram schematically showing the main part of a resonator according to a third embodiment of the present invention.

[0020] Figure 11 FIG. 11 is a diagram for explaining the function of a resonator according to a third embodiment of the present invention.

[0021] Figure 12 FIG. 12 is a diagram schematically showing the main part of a resonator according to a fourth embodiment of the present invention.

[0022] Figure 13 FIG. 13 is a diagram for explaining the function of a resonator according to a fourth embodiment of the present invention.

[0023] Figure 14This is a diagram briefly showing the main part of the resonance device according to the fifth embodiment of the present invention.

[0024] Figure 15 This is a diagram for explaining the function of the resonance device according to the fifth embodiment of the present invention.

[0025] Figure 16 This is a diagram briefly showing the main part of the resonance device according to the sixth embodiment of the present invention. Detailed Embodiments

[0026] [First Embodiment]

[0027] Hereinafter, the first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a perspective view briefly showing the appearance of the resonance device 1 according to the first embodiment of the present invention. In addition, Figure 2 This is an exploded perspective view briefly showing the structure of the resonance device 1 according to the first embodiment of the present invention.

[0028] The resonance device 1 includes a resonator 10 and covers (upper cover 30 and lower cover 20) disposed opposite to each other with the resonator 10 interposed therebetween. That is, the resonance device 1 is constituted by laminating the lower cover 20, the resonator 10, and the upper cover 30 in this order.

[0029] In addition, the resonator 10 is joined to the lower cover 20 and the upper cover 30, thereby sealing the resonator 10 and forming a vibration space for the resonator 10. The resonator 10, the lower cover 20, and the upper cover 30 are each formed using an Si substrate. Moreover, the Si substrates of the resonator 10, the lower cover 20, and the upper cover 30 are joined to each other. The resonator 10 and the lower cover 20 may also be formed using an SOI substrate.

[0030] The resonator 10 is a MEMS resonator manufactured using MEMS technology. In addition, in the present embodiment, an example in which the resonator 10 is formed using a silicon substrate will be described. Hereinafter, each structure of the resonance device 1 will be described in detail.

[0031] (1. Upper Cover 30)

[0032] The upper cover 30 has a rectangular flat plate-shaped bottom plate 32 disposed along the XY plane and side walls 33 extending from the peripheral portion of the bottom plate 32 in the Z-axis direction (that is, the lamination direction of the upper cover 30 and the resonator 10). In the upper cover 30, on the surface facing the resonator 10, a concave portion 31 (an example of a second concave portion) formed by the surface of the bottom plate 32 and the inner surface of the side wall 33 is provided. The concave portion 31 forms a space for the resonator 10 to vibrate, that is, a part of the vibration space.

[0033] (2. Lower Cover 20)

[0034] The lower cover 20 includes a rectangular flat bottom plate 22 disposed along the XY plane, and side walls 23 extending from the peripheral portion of the bottom plate 22 in the Z-axis direction (i.e., the stacking direction of the lower cover 20 and the resonator 10). In the lower cover 20, on the surface facing the resonator 10, a recess 21 (an example of the first recess) formed by the surface of the bottom plate 22 and the inner surface of the side wall 23 is provided. The recess 21 forms a part of the vibration space of the resonator 10. With the above upper cover 30 and lower cover 20, this vibration space is hermetically sealed to maintain a vacuum state. It is also possible to fill a gas such as an inert gas in this vibration space.

[0035] (3. Resonator 10)

[0036] Figure 3 is a top view briefly showing the structure of the resonator 10 according to this embodiment. Using Figure 3 each structure of the resonator 10 according to this embodiment will be described. The resonator 10 includes a vibrating portion 120, a holding portion 140, and a holding arm 110.

[0037] (a) Vibrating portion 120

[0038] The vibrating portion 120 has a rectangular contour extending along the XY plane in the orthogonal coordinate system. The vibrating portion 120 is disposed inside the holding portion 140, and a space is formed between the vibrating portion 120 and the holding portion 140 at a predetermined interval. In Figure 3 the example of, the vibrating portion 120 has a base portion 130 and four vibrating arms 135A to 135D (collectively also referred to as "vibrating arms 135"). In addition, the number of vibrating arms is not limited to four, and is set to any number of one or more, for example. In this embodiment, each vibrating arm 135 is integrally formed with the base portion 130. Figure 3

[0039] The base portion 130 has a front end surface 131A (hereinafter, also referred to as "front end 131A") and a rear end surface 131B (hereinafter, also referred to as "rear end 131B"). The front end 131A and the rear end 131B of the base portion 130 are disposed opposite to each other.

[0040] The base portion 130 is connected to the vibrating arm 135 described later at the front end 131A, and is connected to the holding arm 110 described later at the rear end 131B. The maximum distance between the front end 131A and the rear end 131B of the base portion 130 in the direction from the front end 131A to the rear end 131B, that is, the base length, is about 40 μm. In addition, in the width direction orthogonal to the base length direction, the maximum distance between the side ends of the base portion 130, that is, the base width, is about 300 μm.

[0041] The vibrating arms 135 extend in the Y-axis direction and have the same dimensions respectively. The vibrating arms 135 are respectively arranged parallel to the Y-axis direction between the base 130 and the holding portion 140. One end is connected to the front end 131A of the base 130 to form a fixed end, and the other end is an open end. In addition, the vibrating arms 135 are arranged in parallel at a predetermined interval in the X-axis direction. Further, the width of the vibrating arm 135 in the X-axis direction is about 50 μm, and the length in the Y-axis direction is about 450 μm, for example.

[0042] In the vibrating portion 120 of the present embodiment, two vibrating arms 135A and 135D are arranged on the outside in the X-axis direction, and two vibrating arms 135B and 135C are arranged on the inside. The interval W1 between the vibrating arms 135B and 135C in the X-axis direction is set to be larger than the interval W2 between the outside vibrating arm 135A (135D) in the X-axis direction and the inside vibrating arm 135B (135C) adjacent to the outside vibrating arm 135A (135D). The interval W1 is about 25 μm, and the interval W2 is about 10 μm, for example. By setting the interval W2 to be smaller than the interval W1, the vibration characteristics are improved. In addition, the interval W1 may be set to be smaller than the interval W2, or may be set to an equal interval in order to miniaturize the resonator device 1.

[0043] A protective film 235 is formed on the surface of the vibrating portion 120 (the surface facing the upper cover 30) so as to cover the entire surface. In addition, adjustment films 236A to 236D (hereinafter, the adjustment films 236A to 236D are collectively referred to as "adjustment films 236") are respectively formed on the surfaces of the protective film 235 at the ends on the open end sides of the vibrating arms 135A to 135D. The resonance frequency of the vibrating portion 120 can be adjusted by the protective film 235 and the adjustment films 236.

[0044] The adjustment film 236 is formed such that its surface is exposed in a region where the displacement caused by vibration in the vibrating portion 120 is relatively large. Specifically, the adjustment film 236 is formed at the ends of the vibrating arms 135. On the other hand, the surface of the protective film 235 is exposed in other regions of the vibrating arms 135.

[0045] (b) Holding portion 140

[0046] The holding portion 140 is formed in a rectangular frame shape along the XY plane. When viewed from above, the holding portion 140 is arranged to surround the outside of the vibrating portion 120 along the XY plane. In addition, the holding portion 140 only needs to be arranged at at least a part of the periphery of the vibrating portion 120, and is not limited to the frame shape. For example, the holding portion 140 only needs to be arranged around the vibrating portion 120 to the extent that it can hold the vibrating portion 120 and be joined to the upper cover 30 and the lower cover 20.

[0047] In the present embodiment, it is described that the holding portion 140 is covered with the protective film 235 , but the present invention is not limited thereto, and the protective film 235 may not be formed on the surface of the holding portion 140 .

[0048] (c) Holding arm 110

[0049] The holding arm 110 is provided inside the holding portion 140, and connects the base 130 and the holding portion 140. In addition, the present invention is not limited to this structure, and for example, the holding arm 110 may be formed of a plurality of (for example, two) arms having a curved portion.

[0050] (4.Layered structure)

[0051] use Figure 4 The stacked structure of the resonance device 1 will be described. Figure 4 yes Figure 1 AA′ section view. Figure 5 As shown, in the resonance device 1 according to the present embodiment, the holding portion 140 of the resonator 10 is joined to the side wall 23 of the lower cover 20, and the holding portion 140 of the resonator 10 is joined 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 vibration arm 135 to vibrate is formed by the lower cover 20, the upper cover 30, and the holding portion 140 of the resonator 10.

[0052] The bottom plate 22 and the side wall 23 of the lower cover 20 are integrally formed of a Si (silicon) wafer S1. The lower cover 20 is bonded to the holding portion 140 of the resonator 10 via the upper surface of the side wall 23. The Si wafer S1 is formed of non-degenerate silicon, and its resistivity is, for example, 1 kΩ·cm or more.

[0053] The bottom plate 22 of the lower cover 20 is provided at a position where displacement due to vibration of the vibration arm 135 is maximum. In the present embodiment, the thickness of the lower cover 20 defined in the Z-axis direction is, for example, 150 μm, and the depth of the recess 21 is, for example, 50 μm.

[0054] The upper cover 30 is formed by a Si (silicon) wafer S2 of a predetermined thickness. Figure 5 As shown, the upper cover 30 is bonded to the holding portion 140 of the resonator 10 at its peripheral edge (side wall 33). Preferably, the surface and back surface of the upper cover 30 facing the resonator 10 are covered with a silicon oxide layer S2'. In addition, a structure may be provided in which a gettering layer (not shown) made of Ti (titanium) is formed on the surface of the upper cover 30 facing the resonator 10 inside the recess 31. The gettering layer is a layer for absorbing the gas in the vibration space formed by the upper cover 30 and the lower cover 20 by the gettering effect of titanium, so that the vibration space becomes a vacuum state.

[0055] The bottom plate 32 of the upper cover 30 is disposed at the position where the displacement caused by the vibration of the vibration arm 135 is the largest. In the present embodiment, the thickness of the upper cover 30 defined in the Z-axis direction is, for example, 150 μm, and the depth of the recess 31 is, for example, 50 μm.

[0056] Between the side wall 33 of the upper cover 30 and the holding portion 140, a joining portion H is formed to join the upper cover 30 and the holding portion 140. The joining portion H is formed of a metal layer such as an Al (aluminum) film or a Ge (germanium) film, for example. In addition, the joining portion H may be formed of an Au (gold) film and an Sn (tin) film.

[0057] In the resonator 10, the holding portion 140, the base portion 130, the vibration arm 135, and the holding arm 110 are integrally formed by the same process. In the resonator 10, first, a metal layer E1 is laminated on a Si (silicon) substrate F2 (an example of a substrate). Then, a piezoelectric thin film F3 is laminated on the metal layer E1 so as to cover the metal layer E1, and further, a metal layer E2 is laminated on the piezoelectric thin film F3. A protective film 235 is laminated on the metal layer E2 so as to cover the metal layer E2. On the vibrating portion 120, an adjustment film 236 is further laminated on the protective film 235.

[0058] The Si substrate F2 is formed of a degenerate n-type Si semiconductor having a thickness of about 6 μm, and includes, for example, P (phosphorus), As (arsenic), Sb (antimony), etc. as n-type dopants.

[0059] The metal layers E2 and E1 are formed using Mo (molybdenum), aluminum (Al), etc. having a thickness of about 0.1 to 0.2 μm, for example. The metal layers E2 and E1 are formed into a desired shape by etching or the like. The metal layer E1 functions as a lower electrode (an example of a first electrode layer) on the vibrating portion 120. In addition, the metal layer E1 functions as a wiring for connecting the lower electrode to an AC power source provided outside the resonator 10 on the holding arm 110 or the holding portion 140.

[0060] On the other hand, the metal layer E2 functions as an upper electrode on the vibrating portion 120. In addition, the metal layer E2 functions as a wiring for connecting the upper electrode to a circuit provided outside the resonator 10 on the holding arm 110 or the holding portion 140.

[0061] In addition, when connecting from the AC power source to the lower wiring or the upper wiring, a structure in which an electrode is formed on the outer surface of the upper cover 30 and the electrode connects the circuit to the lower wiring or the upper wiring, or a structure in which a via hole is formed in the upper cover 30 and a conductive material is filled in the interior of the via hole to provide a wiring that connects the AC power source to the lower wiring or the upper wiring can be used.

[0062] The piezoelectric thin film F3 is a thin film of a piezoelectric body that converts an applied voltage into vibration, and can be mainly composed of nitrides or oxides such as AlN (aluminum nitride), for example. Specifically, the piezoelectric thin film F3 can be formed of ScAlN (scandium aluminum nitride). ScAlN is a material obtained by replacing a part of aluminum in aluminum nitride with scandium. In addition, the piezoelectric thin film F3 has a thickness of 1 μm, for example, but can also be used at about 0.2 μm to 2 μm.

[0063] The piezoelectric thin film F3 expands and contracts in the in-plane direction of the XY plane, i.e., the Y-axis direction, according to the electric field applied to the piezoelectric thin film F3 by the metal layers E2 and E1. Due to the expansion and contraction of the piezoelectric thin film F3, the vibrating arm 135 displaces its free end toward the inner surfaces of the lower cover 20 and the upper cover 30 and vibrates in an out-of-plane bending vibration mode.

[0064] In the present embodiment, the phases of the electric fields applied to the outer vibrating arms 135A and 135D are set to be opposite to the phases of the electric fields applied to the inner vibrating arms 135B and 135C. As a result, the outer vibrating arms 135A and 135D and the inner vibrating arms 135B and 135C displace in opposite directions. For example, when the outer vibrating arms 135A and 135D displace the free ends toward the inner surface of the upper cover 30, the inner vibrating arms 135B and 135C displace the free ends toward the inner surface of the lower cover 20.

[0065] The protective film 235 is formed of a material whose mass reduction rate based on etching is slower than that of the adjustment film 236. For example, the protective film 235 is formed of a nitride film such as AlN or SiN, an oxide film such as Ta2O5 (tantalum pentoxide) or SiO2. In addition, the mass reduction rate is represented by the product of the etching rate (the thickness removed per unit time) and the density.

[0066] The adjustment film 236 is formed of a material whose mass reduction rate based on etching is faster than that of the protective film 235. In addition, the adjustment film 236 is formed of a material having a hardness equal to or lower than that of at least the bottom plate 32 of the upper cover 30. The Vickers hardness of the adjustment film 236 is preferably 2 GPa or lower. On the other hand, the Vickers hardness of the bottom plate 32 is preferably 10 GPa or higher. In addition, when the upper cover 30 has a getter layer, the adjustment film 236 has a hardness lower than that of the getter layer, for example, 0.9 GPa or lower.

[0067] For example, the adjustment film 236 is formed of metals such as molybdenum (Mo), tungsten (W), gold (Au), platinum (Pt), nickel (Ni).

[0068] In addition, as long as the relationship between the mass reduction rates of the protective film 235 and the adjustment film 236 is as described above, the magnitude relationship of the etching rates is arbitrary.

[0069] Etching of the protective film 235 and the adjustment film 236 is performed, for example, by irradiating the protective film 235 and the adjustment film 236 with an ion beam (for example, an argon (Ar) ion beam) simultaneously. The ion beam can be irradiated over a range wider than that of the resonator 10. In addition, in the present embodiment, an example of etching using an ion beam is shown, but the etching method is not limited to the method using an ion beam.

[0070] In the resonator device 1 as described above, during vibration in opposite phases, that is, Figure 4 between the vibrating arms 135A and 135B shown, the vibrating arms 135A and 135B vibrate in opposite directions up and down about a central axis r1 extending parallel to the Y-axis. Also, between the vibrating arms 135C and 135D, the vibrating arms 135C and 135D vibrate in opposite directions up and down about a central axis r2 extending parallel to the Y-axis. Thereby, torsional moments in opposite directions are generated on the central axes r1 and r2, and bending vibration is generated at the base 130.

[0071] (5. Process flow)

[0072] Use Figure 5 A method for adjusting the frequency of the resonator 10 according to the present embodiment will be described.

[0073] In the method for adjusting the frequency of the resonator 10 according to the present embodiment, by over-exciting the vibrating arm 135 to collide with the upper cover 30 or the lower cover 20, a part of the vibrating arm 135 (for example, the piezoelectric thin film F3, the adjustment film 236, or the Si substrate F2, etc.) is shaved off, and the weight of the vibrating arm 135 changes. Thereby, by increasing the resonance frequency of the resonator 10, the resonance frequency is adjusted to a desired value.

[0074] Specifically, in the frequency adjustment method, first, the resonance frequency is measured in a state where a driving voltage of a specified value is applied to the resonator 10. When the resonance frequency is lower than the desired value, a voltage larger than the driving voltage of the specified value is applied to the resonator 10 to over-excite the vibrating arm 135. In the frequency adjustment process, the power supplied to the resonator 10 is, for example, 0.2 μW or more. In addition, over-excitation means vibrating with an amplitude 10 times or more the normal amplitude of the resonator 10. Specifically, the amplitude during over-excitation is 50 μm or more. Also, the desired value of the resonance frequency is, for example, around 32.767 to 32.769 kHz.

[0075] By over-exciting the vibrating arm 135, the adjustment film 236 on the vibrating arm 135 collides 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. Since the bottom plate 32 (or the suction layer) of the upper cover 30 is formed of a material having a hardness higher than that of the adjustment film 236, the adjustment film 236 is shaved off by the collision of the adjustment film 236 with the bottom plate 32 (or the suction layer), and the weight of the vibrating arm 135 is reduced. Similarly, at least one of the Si substrate F2 and the silicon oxide layer F21 formed on the surface (back surface) of the vibrating arm 135 on the lower cover 20 side has a hardness equal to or lower than that of the bottom plate 22. Therefore, on the back surface of the vibrating arm 135, the Si substrate F2 or the silicon oxide layer F21 is also shaved off, whereby the mass of the vibrating arm 135 is reduced. As a result, the resonance frequency of the resonator 10 increases.

[0076] After over-exciting the resonator 10 to collide with at least one of the upper cover 30 and the lower cover 20, a driving voltage of a specified value is applied to the resonator 10 again, and the resonance frequency is measured. By repeatedly performing the measurement of the resonance frequency by applying a driving voltage of a specified value to the resonator 10 and over-exciting the resonator 10 by applying a voltage larger than the driving voltage until the resonance frequency reaches a desired value, the value of the resonance frequency is adjusted to an appropriate value.

[0077] In addition, as a frequency adjustment method, in addition to this, a part of the vibrating arm 135 (for example, the piezoelectric thin film F3, the adjustment film 236, or the Si substrate F2, etc.) can be shaved off by irradiating the resonator 10 with an ion beam having a specified pulse width, thereby changing the weight of the resonator 10.

[0078] (6. Function of the resonator)

[0079] As Figure 6 shown, in the present embodiment, in the resonator 10, the opposing portion of the holding portion 140 is located outside the resonator 10 with respect to the straight line L1 that connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135. Specifically, in the resonator 10, the inner end portion P3 of the piezoelectric thin film F3 in the opposing portion of the holding portion 140 is located outside the resonator 10 with respect to the straight line L1.

[0080] In this case, in the resonator 10 according to the present embodiment, during frequency adjustment, that is, in Figure 7In the example shown, when an ion beam with a specified pulse width is irradiated, fragments of the vibrating arm 135 scatter in the traveling direction of the ion beam. Then, the scattered fragments bounce off the bottom surface of the recess 21 of the lower cover 20. In this case, the range in which the fragments scatter is limited to a region inside the resonator 10 relative to the straight line L1. In the example shown in this figure, the range in which the fragments scatter is limited to the range R1 from the bottom of the recess 21 of the lower cover 20 on the end portion side of the vibrating arm 135 to the opening edge. Therefore, fragments scattered from the vibrating arm 135 are less likely to adhere to the inner end portion P3 of the resonator 10 of the piezoelectric film F3, and insulation failure in the piezoelectric film F3 can be suppressed.

[0081] In the resonator 10 according to the present embodiment, the opposing portion of the holding portion 140 is located outside the resonator 10 relative to the straight line L1, which connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 to the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135. Thereby, when adjusting the frequency of the resonator 10, fragments scattered from the vibrating arm 135 are less likely to adhere to the opposing portion of the holding portion 140, and insulation failure in the opposing portion can be suppressed.

[0082] [Second Embodiment]

[0083] After the second embodiment, descriptions of matters common to the first embodiment are omitted, and only differences are described. In particular, the same effects brought about by the same structure are not mentioned in each embodiment in sequence.

[0084] Figure 8 It is a top view briefly showing an example of the structure of the resonator 10 according to the present embodiment. Hereinafter, the description will focus on the points different from the first embodiment in the detailed structure of the resonator 10 according to the present embodiment. The positional relationship between the resonator 10 and the upper cover 30 and the positional relationship between the resonator 10 and the lower cover 20 according to the present embodiment are different from those of the first embodiment.

[0085] As Figure 8 shown, in the present embodiment, in the resonator 10, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located outside the resonator 10 relative to the straight line L2, which connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 to the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P3 of the recess 21 on the end portion side of the vibrating arm 135. Specifically, in the silicon oxide layer S2' formed on the surface of the upper cover 30 facing the resonator 10, the opening edge P4 of the recess 31 of the upper cover 30 is located outside the resonator 10 relative to the straight line L2.

[0086] In this case, in the resonator 10 according to the present embodiment, during frequency adjustment, that is, in Figure 9 In the example shown, when the vibrating arm 135 is over-excited, the adjustment film 236 of the vibrating arm 135 collides with the bottom plate 22 of the lower cover 20, and fragments of the vibrating arm 135 scatter from the bottom surface of the recess 21 of the lower cover 20. In this case, the range in which the fragments scatter is limited to a region inside the resonator 10 with respect to the straight line L2. In the example shown in this figure, the range in which the fragments scatter is limited to the range R1 from the bottom of the recess 21 of the lower cover 20 on the end side of the vibrating arm 135 to the opening edge, and the region R2 on the side surface and the bottom surface of the recess 31 of the upper cover 30 that is above the point where the side surface of the recess 31 intersects the straight line L2. Therefore, the fragments scattered from the vibrating arm 135 are not easily attached to the opening edge P4 of the recess 31 of the upper cover 30 in the silicon oxide layer S2' formed on the surface of the upper cover 30 facing the resonator 10, and insulation failure in the silicon oxide layer S2' can be suppressed.

[0087] In the resonator 10 according to the present embodiment, the opening edge P4 of the recess 31 of the upper cover 30 on the end side of the vibrating arm 135 is located outside the resonator 10 with respect to the straight line L2, and this straight line L2 connects the intersection point P1 of the perpendicular line extending from the end of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P3 of the recess 21 on the end side of the vibrating arm 135. Thereby, when adjusting the frequency of the resonator 10, the fragments scattered from the vibrating arm 135 are not easily attached to the opening edge P4 of the recess 31 of the upper cover 30 on the end side of the vibrating arm 135, and insulation failure in this part can be suppressed.

[0088] [Third Embodiment]

[0089] Figure 10 is a top view briefly showing an example of the structure of the resonator 10 according to the present embodiment. Hereinafter, the description will be centered on the points different from the first embodiment in the detailed structure of the resonator 10 according to the present embodiment. The positional relationship between the resonator 10 according to the present embodiment and the upper cover 30 and the positional relationship with the lower cover 20 are different from those of the first embodiment.

[0090] As Figure 10As shown, in the present embodiment, in the resonator 10, the inner end P3 of the piezoelectric thin film F3 of the resonator 10 is located outside the resonator 10 with respect to the straight line L1, and the straight line L1 connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135. In addition, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located inside the resonator 10 with respect to the straight line L1. Specifically, in the silicon oxide layer S2' formed on the surface of the upper cover 30 facing the resonator 10, the opening edge P4 of the recess 31 of the upper cover 30 is located inside the resonator 10 with respect to the straight line L1.

[0091] In this case, in the resonator 10 according to the present embodiment, during frequency adjustment, that is, Figure 11 In the example shown, during overexcitation of the vibrating arm 135, the adjustment film 236 of the vibrating arm 135 collides with the bottom plate 22 of the lower cover 20, and fragments of the vibrating arm 135 scatter from the bottom surface of the recess 21 of the lower cover 20. In this case, the range in which the fragments scatter is limited to the region inside the resonator 10 with respect to the straight line L1. In the example shown in this figure, the range in which the fragments scatter is limited to the range R1 from the bottom of the recess 21 of the lower cover 20 on the end portion side of the vibrating arm 135 to the opening edge, and the region R2 above the point where the side surface of the recess 31 of the upper cover 30 intersects the straight line L1 on the side surface and the bottom surface of the recess 31 of the upper cover 30. Therefore, the fragments scattered from the vibrating arm 135 are less likely to adhere to the inner end P3 of the piezoelectric thin film F3 of the resonator 10, and insulation failure in the piezoelectric thin film F3 can be suppressed.

[0092] In the resonator 10 according to the present embodiment, the inner end P3 of the piezoelectric thin film F3 of the resonator 10 is located outside the resonator 10 with respect to the straight line L1 connecting the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135, and the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located inside the resonator 10 with respect to the straight line L1. Thereby, when adjusting the frequency of the resonator 10, the fragments scattered from the vibrating arm 135 are less likely to adhere to the inner end P3 of the piezoelectric thin film F3 of the resonator 10, and insulation failure in this part can be suppressed.

[0093] [Fourth Embodiment]

[0094] Figure 12It is a top view briefly showing an example of the structure of the resonator 10 according to the present embodiment. Hereinafter, the description will focus on the points different from the first embodiment in the detailed structure of the resonator 10 according to the present embodiment. The positional relationship between the resonator 10 and the upper cover 30 and the positional relationship between the resonator 10 and the lower cover 20 are different from those of the first embodiment.

[0095] As Figure 12 shown, in the present embodiment, in the resonator 10, the inner end P3 of the piezoelectric thin film F3 in the resonator 10 is located outside the resonator 10 with respect to the straight line L1 that connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135. In addition, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located inside the resonator 10 with respect to the straight line L1. Specifically, the inner end of the resonator 10 in the silicon oxide layer S2' formed on the surface of the upper cover 30 facing the resonator 10 is located inside the resonator 10 with respect to the straight line L1. In addition, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located outside the resonator 10 with respect to the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135.

[0096] In this case, in the resonator 10 according to the present embodiment, during frequency adjustment, that is, in Figure 13 the example shown, when the vibrating arm 135 is over-excited, the adjustment film 236 of the vibrating arm 135 collides with the bottom plate 22 of the lower cover 20, and fragments of the vibrating arm 135 scatter from the bottom surface of the recess 21 of the lower cover 20. In this case, the range of the scattered fragments is limited to the area inside the resonator 10 with respect to the straight line L1. In the example shown in this figure, the range of the scattered fragments is limited to the range R1 from the bottom of the recess 21 of the lower cover 20 on the end portion side of the vibrating arm 135 to the opening edge, and the area R2 above the point where the side surface of the recess 31 of the upper cover 30 intersects with the straight line L1 on the side surface and the bottom surface of the recess 31 of the upper cover 30. Therefore, the fragments scattered from the vibrating arm 135 are not likely to adhere to the inner end P3 of the piezoelectric thin film F3 in the resonator 10, and insulation failure of the piezoelectric thin film F3 can be suppressed.

[0097] In addition, in the present embodiment, the end portion P3 inside the resonator 10 of the piezoelectric thin film F3 and the opening edge P4 of the concave portion 31 of the upper cover 30 on the end portion side of the vibrating arm 135 are both located outside the resonator 10 relative to the opening edge P2 of the concave portion 21 on the end portion side of the vibrating arm 135. Therefore, debris scattered from the vibrating arm 135 during overexcitation is not likely to accumulate in the gap between the outer peripheral portion of the upper cover 30 and the outer peripheral portion of the lower cover 20. Therefore, debris scattered from the vibrating arm 135 is not likely to adhere to the end portion P3 inside the resonator 10 of the piezoelectric thin film F3 and the opening edge P4 of the concave portion 31 of the upper cover 30 on the end portion side of the vibrating arm 135, and insulation failure occurring in these portions can be further suppressed.

[0098] In the resonator 10 according to the present embodiment, the end portion P3 inside the resonator 10 of the piezoelectric thin film F3 and the opening edge P4 of the concave portion 31 of the upper cover 30 on the end portion side of the vibrating arm 135 are both located outside the resonator 10 relative to the opening edge P2 of the concave portion 21 on the end portion side of the vibrating arm 135. Thus, when adjusting the frequency of the resonator 10, debris scattered from the vibrating arm 135 is not likely to accumulate in the gap between the outer peripheral portion of the upper cover 30 and the outer peripheral portion of the lower cover 20, and insulation failure occurring in the portions located within this gap can be further suppressed.

[0099] [Fifth Embodiment]

[0100] Figure 14 It is a top view briefly showing an example of the structure of the resonator 10 according to the present embodiment. Hereinafter, a description will be given centering on the points different from the first embodiment in the detailed structure of the resonator 10 according to the present embodiment. The positional relationship between the resonator 10 according to the present embodiment and the upper cover 30 and the positional relationship with the lower cover 20 are different from those of the first embodiment.

[0101] As Figure 14As shown, in this embodiment, in resonator 10, the inner end P3 of piezoelectric thin film F3 in resonator 10 is located outside resonator 10 with respect to straight line L1. Straight line L1 connects the intersection point P1 of the perpendicular line extending from the end of vibrating arm 135 toward recess 21 of lower cover 20 and recess 21 of lower cover 20, and the opening edge P2 of recess 21 on the end side of vibrating arm 135. In addition, the opening edge P4 of recess 31 of upper cover 30 on the end side of vibrating arm 135 is located outside resonator 10 with respect to straight line L1. Specifically, the inner end of resonator 10 in silicon oxide layer S2' formed on the surface of upper cover 30 facing resonator 10 is located outside resonator 10 with respect to straight line L1. In addition, the opening edge P4 of recess 31 of upper cover 30 on the end side of vibrating arm 135 is located outside resonator 10 with respect to the opening edge P2 of recess 21 on the end side of vibrating arm 135.

[0102] In this case, in resonator 10 according to this embodiment, during frequency adjustment, that is, in Figure 15 In the example shown, during overexcitation of vibrating arm 135, adjustment film 236 of vibrating arm 135 collides with bottom plate 22 of lower cover 20, and fragments of vibrating arm 135 scatter from the bottom surface of recess 21 of lower cover 20. In this case, the range where the fragments scatter is limited to the area inside resonator 10 with respect to straight line L1. In the example shown in this figure, the range where the fragments scatter is limited to range R1 from the bottom of recess 21 of lower cover 20 on the end side of vibrating arm 135 to the opening edge, and area R2 above the point where the side surface of recess 31 of upper cover 30 intersects with straight line L1 in the side surface and bottom surface of recess 31 of upper cover 30. Therefore, fragments scattered from vibrating arm 135 are not likely to adhere to the inner end P3 of piezoelectric thin film F3 in resonator 10 and the opening edge P4 of recess 31 of upper cover 30 on the end side of vibrating arm 135, and insulation failure in piezoelectric thin film F3 can be suppressed.

[0103] In addition, in this embodiment, both the inner end P3 of piezoelectric thin film F3 in resonator 10 and the opening edge P4 of recess 31 of upper cover 30 on the end side of vibrating arm 135 are located outside resonator 10 with respect to the opening edge P2 of recess 21 on the end side of vibrating arm 135. Therefore, fragments scattered from vibrating arm 135 during overexcitation are not likely to accumulate in the gap between the outer peripheral portion of upper cover 30 and the outer peripheral portion of lower cover 20. Therefore, fragments scattered from vibrating arm 135 are not likely to adhere to the inner end P3 of piezoelectric thin film F3 in resonator 10 and the opening edge P4 of recess 31 of upper cover 30 on the end side of vibrating arm 135, and insulation failure in these parts can be further suppressed.

[0104] [Sixth Embodiment]

[0105] Figure 16 It is a top view briefly showing an example of the structure of the resonator 10 according to the present embodiment. Hereinafter, a description will be given centering on the points different from the first embodiment in the detailed structure of the resonator 10 according to the present embodiment. The positional relationship between the resonator 10 and the upper cover 30 and the positional relationship between the resonator 10 and the lower cover 20 according to the present embodiment are different from those of the first embodiment.

[0106] As Figure 16 shown, in the present embodiment, in the resonator 10, the inner end P3 of the piezoelectric thin film F3 of the resonator 10 is located outside the resonator 10 with respect to the straight line L1, and the straight line L1 connects the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20, and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135. In addition, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located outside the resonator 10 with respect to the straight line L1. Specifically, the inner end of the resonator 10 in the silicon oxide layer S2' formed on the surface of the upper cover 30 facing the resonator 10 is located outside the resonator 10 with respect to the straight line L1. In addition, the opening edge P4 of the recess 31 of the upper cover 30 on the end portion side of the vibrating arm 135 is located outside the resonator 10 with respect to the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135.

[0107] In addition, in the present embodiment, in the resonator 10, when the horizontal distance between the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20 and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135 is set to X, and the height difference between the intersection point P1 and the opening edge P2 of the recess 21 is set to Y, 0.1 ≤ X / Y ≤ 2.0, preferably 0.3 ≤ X / Y ≤ 0.7. That is, in the resonator 10, 0.1 ≤ X / Y, preferably 0.3 ≤ X / Y, whereby excessive adhesion of debris scattered from the vibrating arm 135 to the inner side surface of the recess 21 of the lower cover 20 can be suppressed. In addition, in the resonator 10, X / Y ≤ 2.0, preferably X / Y ≤ 0.7, whereby excessive adhesion of the above-mentioned debris can be suppressed and miniaturization of the resonator 10 can be achieved.

[0108] In the resonator 10 according to the present embodiment, when the horizontal distance between the intersection point P1 of the perpendicular line extending from the end portion of the vibrating arm 135 toward the recess 21 of the lower cover 20 and the recess 21 of the lower cover 20 and the opening edge P2 of the recess 21 on the end portion side of the vibrating arm 135 is set as X, and the height difference between the intersection point P1 and the opening edge P2 of the recess 21 is set as Y, 0.1 ≤ X / Y ≤ 2.0, preferably 0.3 ≤ X / Y ≤ 0.7. Therefore, it is possible to suppress excessive adhesion of debris scattered from the vibrating arm 135 to the inner side surface of the recess 21 of the lower cover 20 and to miniaturize the resonator 10.

[0109] Hereinafter, part or all of the embodiments of the present invention will be noted and their effects will be described. In addition, the present invention is not limited to the following notes.

[0110] According to one aspect of the present invention, there is provided a resonant device including: a lower cover having a first recess; and a resonator mounted on the lower cover and having a vibrating arm and a holding portion, the vibrating arm being capable of performing out-of-plane bending vibration in a space including the first recess, the holding portion being provided around the vibrating arm and having an opposing portion opposing the end portion of the vibrating arm, the opposing portion of the holding portion being located outside the resonator with respect to a straight line connecting the intersection point of the perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover and the opening edge of the first recess on the end portion side of the vibrating arm.

[0111] As one aspect, it further includes an upper cover having a second recess and being configured to face the second recess toward the first recess of the lower cover, the resonator being disposed between the upper cover and the lower cover, and the vibrating arm being capable of performing out-of-plane bending vibration in a space including the second recess of the upper cover and the first recess of the lower cover.

[0112] As one aspect, the opening edge of the second recess on the end portion side of the vibrating arm is located inside the resonator with respect to the opening edge of the first recess on the end portion side of the vibrating arm.

[0113] As one aspect, the opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to the opening edge of the first recess on the end portion side of the vibrating arm.

[0114] As one aspect, the opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to a straight line.

[0115] According to one aspect of the present invention, there is provided a resonance device including: a lower cover having a first recess; an upper cover having a second recess and configured to face the first recess of the lower cover; and a resonator disposed between the upper cover and the lower cover and having a vibrating arm and a holding portion. The vibrating arm can perform out-of-plane bending vibration in a space including the first recess of the lower cover and the second recess of the upper cover. The holding portion is provided around the vibrating arm and has an opposing portion opposing the end portion of the vibrating arm. The opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to a straight line connecting the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm.

[0116] As one aspect, when the horizontal distance between the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as X, and the height difference between the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as Y, 0.1 ≤ X / Y ≤ 2.0.

[0117] As one aspect, 0.3 ≤ X / Y ≤ 0.7.

[0118] As described above, according to one aspect of the present invention, when adjusting the resonance frequency of the vibrating arm, it is possible to suppress insulation failure caused by flying objects from the vibrating arm.

[0119] In addition, the above-described embodiments are for facilitating understanding of the present invention and are not construed as limiting the present invention. The present invention can be changed / improved without departing from its gist, and the present invention also includes its equivalents. That is, those skilled in the art can make appropriate design changes to each embodiment, and as long as they have the features of the present invention, they are included in the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, sizes, etc. provided in each embodiment are not limited to those illustrated and can be appropriately changed. In addition, as long as it is technically possible, the elements provided in each embodiment can be combined, and the structure formed by combining them is included in the scope of the present invention as long as it includes the features of the present invention.

[0120] Description of Reference Numerals

[0121] 1…Resonating device; 10…Resonator; 30…Upper cover; 20…Lower cover; 140…Holding portion; 120…Vibrating portion; 130…Base portion; 135A to D…Vibrating arms; F2…Si substrate; 235…Protective film; 236…Adjusting film.

Claims

1. A resonant device, wherein, Comprising: A lower cover having a first recess; and A resonator mounted on the lower cover and having a vibrating arm and a holding portion, the vibrating arm being capable of performing out-of-plane bending vibration in a space including the first recess, and the holding portion being provided around the vibrating arm and having an opposing portion opposing the end portion of the vibrating arm, The opposing portion of the holding portion is located outside the resonator with respect to a straight line that connects the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm.

2. The resonator device according to claim 1, wherein The resonator device further includes an upper cover having a second recess and configured to face the second recess toward the first recess of the lower cover, The resonator is disposed between the upper cover and the lower cover, The vibrating arm is capable of performing out-of-plane bending vibration in a space including the second recess of the upper cover and the first recess of the lower cover.

3. The resonator device according to claim 2, wherein The opening edge of the second recess on the end portion side of the vibrating arm is located inside the resonator with respect to the opening edge of the first recess on the end portion side of the vibrating arm.

4. The resonator device according to claim 2, wherein The opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to the opening edge of the first recess on the end portion side of the vibrating arm.

5. The resonator device according to any one of claims 2 to 4, wherein The opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to the straight line.

6. The resonator device according to any one of claims 2 to 4, wherein When the horizontal distance between the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as X, and the height difference between the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as Y, 0.1 ≤ X / Y ≤ 2.

0.

7. The resonator device according to claim 5, wherein When the horizontal distance between the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as X, and the height difference between the intersection of a perpendicular line extending from the end portion of the vibrating arm toward the first recess of the lower cover and the first recess of the lower cover, and the opening edge of the first recess on the end portion side of the vibrating arm is set as Y, 0.1 ≤ X / Y ≤ 2.

0.

8. The resonator device according to claim 6, wherein 0.3 ≤ X / Y ≤ 0.

7.

9. The resonant device according to claim 7, wherein 0.3 ≤ X / Y ≤ 0.

7.

10. A resonant device, wherein, Comprising: A lower cover having a first recess; An upper cover having a second recess and configured to face the first recess of the lower cover; And A resonator disposed between the upper cover and the lower cover and having a vibrating arm and a holding portion. The vibrating arm can perform out-of-plane bending vibration in a space including the first recess of the lower cover and the second recess of the upper cover. The holding portion is provided around the vibrating arm and has an opposing portion opposing the end portion of the vibrating arm. The opening edge of the second recess on the end portion side of the vibrating arm is located outside the resonator with respect to a straight line connecting the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the opening edge of the first recess on the end portion side of the vibrating arm.

11. The resonant device according to claim 10, wherein When the horizontal distance between the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the opening edge of the first recess on the end portion side of the vibrating arm is set as X, and the height difference between the intersection of the perpendicular line extending from the end portion of the vibrating arm to the first recess of the lower cover and the opening edge of the first recess on the end portion side of the vibrating arm is set as Y, 0.1 ≤ X / Y ≤ 2.

0.

12. The resonant device according to claim 11, wherein 0.3 ≤ X / Y ≤ 0.7.

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