MEMS transducer

Abstract

The present invention provides a MEMS oscillator having a desired resonant frequency that can be manufactured without requiring precise control. [Solution] The MEMS oscillator comprises a substrate having a first main surface and a second main surface located opposite the first main surface, and a cavity recessed from the first main surface toward the second main surface; a vibrating body located within the cavity, extending linearly in a first direction within the plane when the first main surface is viewed from above, and vibrating in a second direction intersecting the first direction within the plane; and a plurality of support parts located within the cavity, supporting the vibrating body from the second direction at a plurality of support positions spaced apart from each other along the first direction.

Description

Technical Field

[0001] The present disclosure relates to a MEMS oscillator.

Background Art

[0002] Patent Document 1 describes a Micro Electro Mechanical System (MEMS) type resonator including a substrate, an input electrode disposed on the substrate, and a vibrating electrode facing the input electrode with a gap therebetween. The vibrating electrode is a thin film layer such as a polycrystalline silicon film or a metal film formed by a thin film deposition method. When a constant voltage is applied to the vibrating electrode and a high-frequency signal is input to the input electrode, the vibrating electrode vibrates in the film thickness direction due to the electrostatic force generated between the vibrating electrode and the input electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] [Summary] In Patent Document 1, the resonance frequency of the MEMS type resonator depends on the film thickness of the vibrating electrode. However, precise control is required for controlling the film thickness dimension in the thin film deposition method.

[0005] An object of the present disclosure is to provide a MEMS oscillator having a desired resonance frequency that can be manufactured without requiring precise control.

[0006] The MEMS oscillator according to one aspect of the present disclosure has a first main surface and a second main surface disposed on the opposite side of the first main surface, and a substrate in which a cavity recessed from the first main surface toward the second main surface is disposed; a vibrating body disposed in the cavity, linearly extending in a first direction in the plane when the first main surface is viewed in plan view, and vibrating in a second direction intersecting the first direction in the plane; A plurality of support parts are arranged within the cavity and at a plurality of support positions spaced apart from each other along the first direction, supporting the vibrating body from the second direction. It is equipped with. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a plan view of a MEMS oscillator according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a magnified view showing the area around the vibrating electrode shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 2. [Figure 4] Figure 4 is a magnified view showing the area around the fixed electrode shown in Figure 1 after the thermal oxidation process. [Figure 5] Figure 5 is a diagram illustrating the operation of the MEMS oscillator shown in Figure 1. [Figure 6] Figure 6 is a diagram similar to Figure 5, relating to one modified example of the above embodiment. [Figure 7] Figure 7 is a diagram similar to Figure 2, relating to another modified example of the above embodiment. [Figure 8] Figure 8 is a diagram similar to Figure 4, relating to yet another modification of the above embodiment.

[0008] [Detailed explanation] Hereinafter, a MEMS oscillator according to an embodiment of this disclosure will be described with reference to the accompanying drawings. The following description is essentially illustrative and is not intended to limit this disclosure, its applications, or its uses. Furthermore, the drawings are schematic, and the proportions of the dimensions may differ from those of actual objects.

[0009] Figure 1 is a plan view of the MEMS oscillator 1 of this embodiment. Figure 2 is an enlarged view showing the area around the vibrating electrode 20 shown in Figure 1. Figure 3 is a cross-sectional view along line III-III in Figure 2.

[0010] In the following description, for convenience, in the plan view shown in Figure 1, the left-right direction along each side of the MEMS oscillator 1 will be referred to as the X direction, and the up-down direction in Figure 1 will be referred to as the Y direction. In the cross-sectional view shown in Figure 3, the thickness direction of the MEMS oscillator 1 (up-down direction in Figure 3) will be referred to as the Z direction. In particular, in Figure 1, the right side may be referred to as the +X direction, the left side as the -X direction, the upper side as the +Y direction, and the lower side as the -Y direction. In Figure 3, the upper side may be referred to as the +Z direction and the lower side as the -Z direction. In this embodiment, the X direction, Y direction, and Z direction are orthogonal to each other. The X direction in this embodiment is an example of the first direction according to this disclosure, and the Y direction in this embodiment is an example of the second direction according to this disclosure.

[0011] The MEMS resonator 1 of this embodiment is an electrostatic resonator manufactured using semiconductor microfabrication technology. Referring to Figure 1, the MEMS resonator 1 comprises a substrate 10, a vibrating electrode 20, and a plurality of fixed electrodes 30A to 30D. In the following description, when there is no need to particularly distinguish between the plurality of fixed electrodes 30A to 30D, one of the plurality of fixed electrodes 30A to 30D may simply be referred to as fixed electrode 30.

[0012] The substrate 10 is a conductive silicon (Si) substrate. The substrate 10 has a first main surface 10a (shown in Figure 3) located on the +Z side and a second main surface 10b (shown in Figure 3) located on the -Z side. The first main surface 10a and the second main surface 10b are planar, extending in the X and Y directions. The first main surface 10a and the second main surface 10b extend parallel to each other. An insulating layer 11 (shown in Figure 3) made of silicon oxide (SiO2) is laminated on the first main surface 10a. The thickness direction of the substrate 10 coincides with the Z direction. A rectangular cavity 12 in plan view is formed in the substrate 10, recessed from the first main surface 10a towards the -Z side. The substrate 10 has a rectangular bottom wall 13 (shown in plan view) that defines the -Z side of the cavity 12.

[0013] The vibrating electrode 20 is located inside the cavity 12. Referring to Figure 2, the vibrating electrode 20 comprises a vibrating body 21, a plurality of anchors 22A to 22F, and a plurality of support parts 23A to 23J. In the following description, when it is not necessary to distinguish between each of the plurality of anchors 22A to 22F, one of the plurality of anchors 22A to 22F may simply be referred to as anchor 22. In the following description, when it is not necessary to distinguish between each of the plurality of support parts 23A to 23J, one of the plurality of support parts 23A to 23J may simply be referred to as support part 23.

[0014] The vibrating body 21 vibrates in the Y direction at its natural resonant frequency when excited by the fixed electrode 30. As shown in Figure 3, the vibrating body 21 is spaced apart from the bottom wall 13 of the substrate 10 on the +Z side. Referring to Figure 2, the vibrating body 21 is a plate-like structure that extends elongated in the X direction in a plan view. Specifically, the vibrating body 21 is a plate-like structure with the X direction as the longitudinal direction, the Y direction as the thickness direction, and the Z direction as the short direction. The vibrating body 21 is supported from both sides in the Y direction by support parts 23 at multiple support positions arranged at equal intervals along the X direction.

[0015] The vibrating body 21 comprises a main body 21a and a deformation suppression part 21b disposed within the main body 21a and having a different coefficient of thermal expansion than that of the main body 21a. In this embodiment, the main body 21a is made of conductive silicon, and the deformation suppression part 21b is made of silicon oxide. The main body 21a is a rectangular plate with the X direction as its longitudinal direction. The deformation suppression part 21b traverses the main body 21a in the X and Z directions, dividing the main body 21a in the Y direction. The deformation suppression part 21b mechanically connects the two sides of the main body 21a that are divided in the Y direction by the deformation suppression part 21b. In this embodiment, the deformation suppression part 21b extends continuously along the entire length of the vibrating body 21 in the X direction.

[0016] The anchor 22 supports the vibrating body 21 and the support portion 23 in a state separated from the bottom wall 13 on the +Z side. As shown in FIG. 3, the anchor 22 is fixed to the bottom wall 13 of the substrate 10. The anchors 22A to 22C are arranged on the +Y side with respect to the vibrating body 21, and the anchors 22D to 22F are arranged on the -Y side with respect to the vibrating body 21.

[0017] The support portion 23 supports the vibrating body 21 in a state separated from the bottom wall 13 of the substrate 10 on the +Z side while allowing the vibration of the vibrating body 21. As shown in FIG. 3, the support portion 23 is separated from the bottom wall 13 of the substrate 10 on the +Z side. Further, the support portion 23 supports the vibrating body 21 over the entire length of the vibrating body 21 in the Z direction. Referring to FIG. 2, the support portion 23 extends in the Y direction. One end of the support portion 23 is connected to the anchor 22, and the other end of the support portion 23 is connected to the vibrating body 21. The support portion 23 is supported by the anchor 22 in a cantilever manner. The support portion 23 includes a base portion 23a connected to the anchor 22 and a tip portion 23b connected to the vibrating body 21. The width of the tip portion 23b, that is, the dimension in the X direction, is smaller than the width of the base portion 23a, that is, the dimension in the X direction.

[0018] The plurality of support portions 23A to 23E are arranged on the +Y side with respect to the vibrating body 21, and the plurality of support portions 23F to 23J are arranged on the -Y side with respect to the vibrating body 21. The plurality of support portions 23A to 23E are arranged at equal intervals in the X direction. Further, the plurality of support portions​​​The vibrating electrode 20 has a plurality of isolation joints 24A to 24J that correspond one-to-one to the plurality of support portions 23A to 23J. In the following description, when it is not necessary to particularly distinguish each of the plurality of isolation joints 24A to 24J, one of the plurality of isolation joints 24A to 24J may be simply referred to as the isolation joint 24.

[0020] The isolation joint 24 traverses the corresponding support portion 23 in the X and Z directions and divides it in the Y direction. The isolation joint 24 mechanically connects the two portions on both sides of the corresponding support portion 23 that are divided in the Y direction by the isolation joint 24 while electrically insulating them. The isolation joint 24 electrically insulates the vibrating body 21 and the anchor 22. The isolation joint 24 is disposed at the base portion 23a of the support portion 23. The isolation joint 24 of the present embodiment is made of silicon oxide.

[0021] The vibrating electrode 20 includes an electrode pad 25 disposed on the anchor 22F. The electrode pad 25 is electrically connected to a wiring layer 26 that extends across the isolation joint 24J. The wiring layer 26 is electrically connected to the vibrating body 21 through a via 27 that penetrates the insulating layer 11 in the Z direction. The electrode pad 25 is electrically connected to the vibrating body 21 through the wiring layer 26 and the via 27. A constant voltage is applied to the vibrating body 21 through the electrode pad 25. The electrode pad 25 is disposed on the insulating layer 11, and the electrode pad 25 and the anchor 22F are electrically insulated by the insulating layer 11.

[0022] Referring to FIG. 1, the fixed electrode 30 includes an electrode portion 31, an anchor 32, and a connecting portion 33. The fixed electrodes 30A and 30B are disposed on the +Y side with respect to the vibrating body 21, and the fixed electrodes 30C and 30D are disposed on the -Y side with respect to the vibrating body 21.

[0023] The electrode portion 31 is made of conductive silicon. The electrode portion 31 is positioned spaced apart from the bottom wall 13 of the substrate 10 on the +Z side. The electrode portion 31 is positioned away from the vibrating body 21 in the Y direction and facing the vibrating body 21. The electrode portion 31 is plate-shaped and extends in the X and Z directions. In this embodiment, the electrode portions 31 of the fixed electrodes 30A and 30B function as driving electrodes for vibrating the vibrating body 21, and the electrode portions 31 of the fixed electrodes 30C and 30D function as detection electrodes for detecting the vibration of the vibrating body 21.

[0024] The anchor 32 supports the electrode portion 31 and the connecting portion 33, spaced apart from the bottom wall 13 of the substrate 10 in the +Z direction. The anchor 32 is fixed to the bottom wall 13 of the substrate 10.

[0025] The connecting portion 33 connects the electrode portion 31 and the anchor 32. The connecting portion 33 is positioned spaced apart from the bottom wall 13 of the substrate 10 on the +Z side. The connecting portion 33 extends in the Y direction. One end of the connecting portion 33 is mechanically connected to the anchor 32 via an isolation joint 34. The anchor 32 and the connecting portion 33 are electrically insulated and mechanically connected by the isolation joint 34. The connecting portion 33 is cantilevered to the anchor 32. The other end of the connecting portion 33 is connected to the electrode portion 31.

[0026] The connecting section 33 includes a spring 40 and a beam 50.

[0027] The spring 40 is elastically deformable in the Y direction. The spring 40 has a plurality of annular sections 41A to 41C arranged in the Y direction. In the following description, when it is not necessary to distinguish between each of the plurality of annular sections 41A to 41C, one of the plurality of annular sections 41A to 41C may simply be referred to as annular section 41.

[0028] Of the multiple annular sections 41A to 41C, two annular sections 41, 41 that are adjacent to each other in the Y direction are connected. The annular section 41 is rectangular in shape with the X direction as its longitudinal direction in a plan view. The annular section 41 has a pair of flexible beams 42A and 42B that constitute a pair of long sides of the annular section 41. The flexible beam 42A that constitutes the long side on the +Y side extends in the X direction and is curved so as to be convex towards the +Y side. The flexible beam 42B that constitutes the long side on the -Y side extends in the X direction and is curved so as to be convex towards the -Y side. In the following description, when there is no need to particularly distinguish between the pair of flexible beams 42A and 42B, one of the pair of flexible beams 42A and 42B may simply be referred to as flexible beam 42.

[0029] As shown in Figure 2, the flexible beam 42 comprises a first portion 42a extending in the X direction and a second portion 42b extending in the X direction, having a thermal expansion coefficient smaller than that of the first portion 42a. In this embodiment, the first portion 42a is made of conductive silicon, and the second portion 42b is made of silicon oxide. In the flexible beam 42A, the second portion 42b is positioned adjacent to the first portion 42a on the +Y side, and in the flexible beam 42B, the second portion 42b is positioned adjacent to the first portion 42a on the -Y side.

[0030] The second portion 42b of the spring 40 is obtained by thermal oxidation of the substrate 10. Thermal oxidation of the substrate 10 is carried out at a high temperature (for example, 800°C to 1200°C). Referring to the enlarged view of the area around the fixed electrode 30 at the stage when the second portion 42b is manufactured in the thermal oxidation process shown in Figure 4, at the stage shown in Figure 4, the flexible beam 42 extends linearly in the X direction. When the MEMS oscillator 1 formed at the high temperature shown in Figure 4 cools to room temperature, the spring 40 experiences thermal stress in the first portion 42a that is greater than that in the second portion 42b, due to the difference in thermal expansion coefficients between the first portion 42a and the second portion 42b. As a result, the amount of contraction of the first portion 42a is greater than that of the second portion 42b, the flexible beam 42 curves as shown in Figure 1, and the spring 40 as a whole deforms to stretch in the Y direction.

[0031] Due to the deformation of the spring 40, the electrode portion 31 moves from the state shown in Figure 4 to the state shown in Figure 1, approaching the vibrating body 21. This makes it possible to narrow the distance G (shown in Figure 2) between the vibrating body 21 and the electrode portion 31 compared to the distance G0 before the spring 40 deformed. As a result, the distance G between the vibrating body 21 and the electrode portion 31 can be narrowed compared to the distance G0 formed between the vibrating body 21 and the electrode portion 31 by etching to form the vibrating body 21 and the electrode portion 31. Consequently, the distance between the vibrating body 21 and the electrode portion 31 can be narrowed regardless of the aspect ratio limit of the etching, thereby improving the performance of the MEMS oscillator 1.

[0032] Referring to Figure 1, the beam 50 extends in the Y direction. One end of the beam 50 is connected to the spring 40. The other end of the beam 50 is connected to the electrode portion 31. The beam 50 is provided with two protrusions 51A and 51B. In the following description, when it is not necessary to distinguish between the protrusions 51A and 51B, one of the protrusions 51A and 51B may simply be referred to as protrusion 51.

[0033] The protrusions 51A and 51B each project from the beam 50 toward both sides in the X direction and extend toward the electrode portion 31 in the Y direction via the bent portion. That is, the protrusions 51A and 51B are L-shaped in plan view. An insulator 52 is placed at the tip of each of the protrusions 51A and 51B. The insulator 52 in this embodiment is made of silicon oxide.

[0034] The fixed electrode 30 includes an electrode pad 35 positioned on the anchor 32. The electrode pad 35 is electrically connected to a wiring layer 36 extending across the isolation joint 34. The wiring layer 36 is electrically connected to the electrode portion 31 via a via 37 penetrating the insulating layer 11 in the Z direction. The electrode pad 35 is electrically connected to the electrode portion 31 via the wiring layer 36 and the via 37. An AC voltage is applied to the electrode portion 31 of the fixed electrodes 30A and 30B via the electrode pad 35 to drive the vibrating body 21. A constant voltage is applied to the electrode portion 31 of the fixed electrodes 30C and 30D via the electrode pad 35 to detect the change in capacitance formed between the fixed electrodes 30C and 30D and the vibrating body 21 due to the vibration of the vibrating body 21. The electrode pad 35 is positioned on the insulating layer 11, and the insulating layer 11 electrically insulates the anchor 32 from the electrode pad 35.

[0035] The MEMS transducer 1 has a restricting portion 60 connected to the anchor 22 of the vibrating electrode 20. The restricting portion 60 protrudes in the X direction from the anchor 22 of the vibrating electrode 20. Also, in the state shown in Figure 4, the restricting portion 60 and the protruding portion 51 are spaced apart in the Y direction. The restricting portion 60 restricts the displacement of the electrode portion 31 by contacting the protruding portion 51 when the spring 40 of the fixed electrode 30 deforms due to thermal stress and the electrode portion 31 is displaced by a predetermined distance toward the vibrating body 21. In this way, the restricting portion 60 maintains the distance between the electrode portion 31 and the vibrating body 21 at a predetermined distance. When the protruding portion 51 contacts the restricting portion 60, the insulator 52 also contacts the restricting portion 60, so the electrode portion 31 and the anchor 22 of the vibrating electrode 20 are electrically insulated.

[0036] As shown in Figure 1, the MEMS oscillator 1 includes a plurality of electrostatic chucks 70A to 70F for fixing the fixed electrode 30 to the restricting section 60 by electrostatic force. In the following description, when it is not necessary to distinguish between each of the plurality of electrostatic chucks 70A to 70F, one of the plurality of electrostatic chucks 70A to 70F may simply be referred to as electrostatic chuck 70. The electrostatic chuck 70 includes a beam 71 and one or two electrode sections 72.

[0037] The beam 71 is made of conductive silicon. The beam 71 extends in the Y direction. One end of the beam 71 is connected to the substrate 10 via an isolation joint 73. The beam 71 and the substrate 10 are electrically insulated and mechanically connected by the isolation joint 73. The other end of the beam 71 is connected to the anchor 22 of the vibrating electrode 20 via an isolation joint 74. The beam 71 and the anchor 22 are electrically insulated and mechanically connected by the isolation joint 74. The isolation joints 73 and 74 in this embodiment are made of silicon oxide.

[0038] One or two electrode portions 72 are made of conductive silicon. One or two electrode portions 72 protrude from the beam 71 in the X direction. Specifically, each of the electrostatic chuck portions 70A and 70D has one electrode portion 72 protruding from the beam 71 toward the +X side. Each of the electrostatic chuck portions 70B and 70E has two electrode portions 72 protruding from the beam 71 toward both sides in the X direction, respectively. Each of the electrostatic chuck portions 70C and 70F has one electrode portion 72 protruding from the beam 71 toward the -X side. The electrode portions 72 extend in the X direction and are spaced apart in the Y direction so as to face the flexible beam 42 of the corresponding spring 40.

[0039] The electrostatic chuck portion 70 includes an electrode pad 75 disposed on the substrate 10. The electrode pad 75 is electrically connected to a wiring layer 76 that extends across the isolation joint 73. The wiring layer 76 is electrically connected to the electrode portion 72 via a via 77 that penetrates the insulating layer 11 in the Z direction. The electrode pad 75 is electrically connected to the electrode portion 72 via the wiring layer 76 and the via 77. The electrode pad 75 is disposed on the insulating layer 11, and the insulating layer 11 electrically insulates the electrode pad 75 from the substrate 10. When a voltage different from the voltage applied to the flexible beam 42 of the opposing spring 40 is applied to the electrode portion 72 of the electrostatic chuck portion 70 via the electrode pad 75, an electrostatic force of mutual attraction acts between the electrode portion 72 of the electrostatic chuck portion 70 and the flexible beam 42 of the opposing spring 40.

[0040] Figure 5 is a schematic diagram illustrating the operation of the MEMS oscillator 1 in this embodiment. Referring to Figure 5, when a constant voltage is applied to the vibrating body 21 and an AC voltage is applied to the electrode portions 31 of the fixed electrodes 30A and 30B, the vibrating body 21 vibrates at its resonant frequency due to the electrostatic force acting between the vibrating body 21 and the electrode portions 31 of the fixed electrodes 30A and 30B. When the vibrating body 21 vibrates, the distance between the vibrating body 21 and the electrode portions 31 of the fixed electrodes 30C and 30D changes, and the capacitance of the capacitor formed by the vibrating body 21 and the respective electrode portions 31 of the fixed electrodes 30C and 30D changes. From this change in capacitance, an electrical signal having the same frequency as the resonant frequency of the vibrating body 21 is extracted as an output from the electrode pad 35.

[0041] [effect] The MEMS oscillator 1 of this embodiment provides the following effects.

[0042] (1) The MEMS oscillator 1 is A substrate 10 having a first main surface 10a and a second main surface 10b located on the opposite side of the first main surface 10a, and a cavity 12 recessed from the first main surface 10a toward the second main surface 10b is provided, A vibrating body 21 is placed within the cavity 12, extends linearly in a first direction (in this embodiment, the X direction) within the plane when the first main surface 10a is viewed from above, and vibrates in a second direction (in this embodiment, the Y direction) that intersects the first direction within that plane, A plurality of support parts 23 are arranged within the cavity 12 and are spaced apart from each other along the first direction, supporting the vibrating body 21 from the second direction. It is equipped with.

[0043] The resonant frequency of a MEMS oscillator is primarily determined by the dimensions of the vibrator in its vibration direction. In the case of a MEMS oscillator having a vibrator that is a thin film layer mounted on a substrate and vibrating in the thickness direction of the substrate, the vibrator is manufactured by thin-film deposition. Generally, controlling the film thickness in thin-film deposition requires more precise control than controlling the pattern dimensions in etching. In contrast, in this configuration, the vibrator 21 vibrates in the Y direction extending within the plane when the first main surface 10a of the substrate 10 is viewed from above. In other words, since the vibration direction of the vibrator 21 is perpendicular to the thickness direction of the substrate 10, the dimensions of the vibrator 21 in its vibration direction can be controlled as the pattern dimensions in etching. As a result, a MEMS oscillator 1 with a desired resonant frequency can be manufactured without requiring precise control.

[0044] (2) The multiple support parts 23 each support the vibrating body 21 continuously along the entire length of the vibrating body 21 in the thickness direction of the substrate 10 (Z direction in this embodiment) at their respective support positions.

[0045] With this configuration, the displacement of the vibrating body 21 is constrained along its entire length in the Z direction at each support position, thereby suppressing the vibrating body 21 from vibrating in unintended ways.

[0046] (3) The vibrating body 21 comprises a silicon body 21a and a deformation suppression part 21b disposed inside the body 21a and having a thermal expansion coefficient smaller than that of the body 21a.

[0047] With this configuration, a deformation suppression section 21b having a thermal expansion coefficient smaller than that of the main body 21a is arranged inside the main body 21a, thereby suppressing dimensional changes of the vibrating body 21 due to temperature changes. As a result, changes in the resonant frequency of the MEMS oscillator 1 due to temperature changes can be suppressed.

[0048] (4) The MEMS oscillator 1 comprises an electrode portion 31 for vibrating the vibrating body 21, which is positioned facing the vibrating body 21 in a second direction (in this embodiment, the Y direction); an anchor 32 fixed to the substrate 10 for supporting the electrode portion 31; and a connecting portion 33 connecting the electrode portion 31 and the anchor 32. The connecting portion 33 has a first portion 42a having a first coefficient of thermal expansion, and a second portion 42b positioned adjacent to the first portion 42a in the second direction and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion. The connecting portion 33 is deformed by the difference between the thermal stress generated in the first portion 42a and the thermal stress generated in the second portion 42b, and the deformation of the connecting portion 33 is configured such that the distance between the vibrating body 21 and the electrode portion 31 becomes narrower compared to before the deformation of the connecting portion 33.

[0049] In an electrostatic resonator, the amplitude of the electrical signal obtained as output increases as the distance between the vibrating body 21 and the electrode portion 31 decreases. However, because there is a limit to the aspect ratio of etching, the distance between the vibrating body 21 and the electrode portion 31 increases as the etching deepens. In other words, when etching the space between the vibrating body 21 and the electrode portion 31 to a predetermined depth, it is difficult to make the distance between the vibrating body 21 and the electrode portion 31 narrower than a certain distance. In contrast, with this configuration, the connecting portion 33 is deformed by the difference between the thermal stress generated in the first portion 42a and the thermal stress generated in the second portion 42b, and this deformation of the connecting portion 33 makes it possible to make the distance between the vibrating body 21 and the electrode portion 31 narrower than the distance before the connecting portion 33 was deformed. As a result, the distance between the vibrating body 21 and the electrode portion 31 can be made narrower than the distance formed between the vibrating body 21 and the electrode portion 31 by etching to form the vibrating body 21 and the electrode portion 31. As a result, regardless of the etching aspect ratio limit, the gap between the vibrating body 21 and the electrode portion 31 can be narrowed, thereby increasing the amplitude of the electrical signal obtained as output in the MEMS oscillator 1.

[0050] (5) The MEMS oscillator 1 has a restricting portion 60 that restricts the displacement of the electrode portion 31 by contacting the connecting portion 33 when the electrode portion 31 is displaced a predetermined distance toward the vibrating body 21 due to deformation of the connecting portion 33.

[0051] With this configuration, the regulating part 60 restricts the displacement of the electrode part 31 in the Y direction, so that the distance between the vibrating body 21 and the electrode part 31 can be maintained at a predetermined distance regardless of manufacturing tolerances or temperature changes.

[0052] (6) The MEMS oscillator 1 is positioned facing the connecting portion 33 in a second direction (in this embodiment, the Y direction), and includes an electrostatic chuck portion 70 that generates an electrostatic force between itself and the connecting portion 33 when a voltage different from the voltage applied to the electrode portion 31 is applied, and pulls the connecting portion 33 so that the electrode portion 31 faces the vibrating body 21.

[0053] By generating an electrostatic force that attracts each other between the electrode portion 31 and the connecting portion 33, it is possible to suppress unintended changes in the distance between the vibrating body 21 and the electrode portion 31, even when vibration or shock is applied to the MEMS resonator 1 while the restricting portion 60 and the connecting portion 33 are in contact.

[0054] [Differentiation] The MEMS oscillator relating to this disclosure is not limited to the configuration of the embodiment described above, and various modifications are possible.

[0055] Figure 6 is a diagram similar to Figure 5, relating to a modified example of the above embodiment. In Figure 6, the fixed electrode 30 that functions as a driving electrode is hatched to distinguish it from the fixed electrode 30 that functions as a detection electrode. In the modified example shown in Figure 6, a pair of fixed electrodes 30, 30 are arranged on both sides of the vibrating body 21 in the Y direction. In the modified example shown in Figure 6, multiple pairs of fixed electrodes 30, 30 are arranged in the X direction. AC voltages with opposite phases are applied to the pair of fixed electrodes 30, 30 that function as driving electrodes. The MEMS resonator 1 in the modified example shown in Figure 6 is a differential drive type MEMS resonator. In addition, the same constant voltage is applied to the pair of fixed electrodes that function as detection electrodes. The MEMS resonator 1 in the modified example shown in Figure 6 is a differential detection type MEMS resonator.

[0056] In the above embodiment, the deformation suppression portion 21b extended continuously in the X direction within the main body 21a, but is not limited to this. The deformation suppression portion 21b may be arranged intermittently in the X direction, as shown in the modified example in Figure 7.

[0057] Figure 8 is a diagram similar to Figure 4, relating to yet another modification of the above embodiment. In the modification shown in Figure 8, the insulator 52 of the beam 50 is an isolation joint that traverses the corresponding projection 51 in the X and Z directions and divides the corresponding projection 51 in the Y direction. In the modification shown in Figure 8, the insulator 52 electrically insulates the portions of the corresponding projection 51 that are mechanically connected on both sides of the projection 51 that are divided in the Y direction by the insulator 52. At the tips of the projections 51A and 51B shown in Figure 8, there is a tip portion 53 that is positioned facing each other in the Y direction from the restricting portion 60 and extends in the X direction. The tip portion 53 is made of conductive silicon.

[0058] In the modified example shown in Figure 8, the restricting portion 60 comprises a main body 61 protruding in the X direction from the anchor 22 of the vibrating electrode 20, and a stopper 62 protruding from the main body 61 toward the tip portion 53. In the plan view shown in Figure 8, the stopper 62 is triangular in shape, tapering toward the tip portion 53. The stopper 62 is not limited to a triangular shape and may have other shapes, such as a trapezoidal shape, tapering toward the tip portion 53 in a plan view. In the modified example shown in Figure 8, the gap formed between the tip of the stopper 62 and the tip portion 53 by etching to form the restricting portion 60 and the beam 50 is narrower than the gap G0 formed between the vibrating body 21 and the electrode portion 31 by etching to form the vibrating body 21 and the electrode portion 31.

[0059] The gap formed between the main body 61 and the tip portion 53 by etching is difficult to make narrower than a predetermined gap due to the limitations of the etching aspect ratio. Therefore, if one attempts to make the gap formed between the main body 61 and the tip portion 53 by etching narrower than the gap formed between the vibrating body 21 and the electrode portion 31 by etching, it becomes necessary to widen the gap formed between the vibrating body 21 and the electrode portion 31 more than necessary. In other words, the gap formed between the vibrating body 21 and the electrode portion 31 must be made wider than the smallest gap that can be formed between the vibrating body 21 and the electrode portion 31 by etching. On the other hand, a stopper 62 that partially protrudes from the main body 61 can be manufactured regardless of the limitations of the etching aspect ratio. Therefore, in the modified example shown in Figure 8, regardless of the limitations of the etching aspect ratio, a gap G1 narrower than the gap G0 formed between the vibrating body 21 and the electrode portion 31 by etching can be formed between the stopper 62 and the tip portion 53 by etching. In this way, by providing a stopper 62 that protrudes from the main body 61 toward the tip 53, the distance the tip 53 moves when the electrode portion 31 deforms to approach the vibrating body 21 due to the deformation of the spring 40 can be shortened compared to a configuration in which the stopper 62 is not provided.

[0060] According to the modified MEMS oscillator 1 shown in Figure 8, the gap G1 formed between the restricting portion 60 and the tip portion 53 by etching can be made narrower than the gap G0 formed between the vibrating body 21 and the electrode portion 31 by etching. Therefore, when the electrode portion 31 deforms to approach the vibrating body 21 due to the deformation of the spring 40, the stopper 62 and the tip portion 53 come into contact before the vibrating body 21 and the electrode portion 31 come into contact, thereby suppressing contact between the electrode portion 31 and the vibrating body 21. As a result, the desired gap between the vibrating body 21 and the electrode portion 31 can be achieved while suppressing contact between the vibrating body 21 and the electrode portion 31.

[0061] In the above embodiment, an electrostatic resonator was described as an example of a MEMS oscillator according to the disclosure. However, the MEMS oscillator according to the disclosure may be applied to filters, oscillators, temperature sensors, mass sensors, gyro sensors, or motion sensors.

[0062] [Note] The MEMS oscillator relating to this disclosure provides the following embodiments.

[0063] [Aspect 1] A substrate having a first main surface and a second main surface located opposite the first main surface, wherein a cavity recessed from the first main surface toward the second main surface is provided, A vibrating body is disposed within the cavity, extending linearly in a first direction within the plane when the first main surface is viewed from above, and vibrating in a second direction intersecting the first direction within the plane; A plurality of support parts are arranged within the cavity and at a plurality of support positions spaced apart from each other along the first direction, supporting the vibrating body from the second direction. A MEMS oscillator equipped with [a specific feature].

[0064] [Aspect 2] The MEMS resonator according to embodiment 1, wherein the plurality of support portions each support the vibrating body over the entire vibrating body in the thickness direction of the substrate at their respective support positions.

[0065] [Aspect 3] The vibrating body is The body is made of silicone, A deformation-suppressing portion is disposed within the main body and has a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the main body. A MEMS oscillator according to embodiment 1 or 2, comprising:

[0066] [Aspect 4] An electrode portion for vibrating the vibrating body is positioned facing the vibrating body in the second direction, An anchor fixed to the substrate and supporting the electrode portion, A connecting portion that connects the electrode portion and the anchor. Equipped with, The aforementioned connecting portion is A first part having a first thermal expansion coefficient, A second portion is positioned adjacent to the first portion in the second direction and has a second thermal expansion coefficient different from the first thermal expansion coefficient. It has, The MEMS oscillator according to any one of embodiments 1 to 3, wherein the connecting portion is deformed by the difference between the thermal stress generated in the first portion and the thermal stress generated in the second portion, and the deformation of the connecting portion causes the distance between the vibrating body and the electrode portion to become narrower compared to before the deformation of the connecting portion.

[0067] [Aspect 5] The MEMS vibrator according to embodiment 4, further comprising a restricting portion that restricts the displacement of the electrode portion by contacting the connecting portion when the electrode portion is displaced a predetermined distance toward the vibrating body due to deformation of the connecting portion.

[0068] [Aspect 6] The MEMS resonator according to embodiment 5, comprising an electrostatic chuck portion positioned facing the connecting portion in the second direction, which generates an electrostatic force between itself and the connecting portion when a voltage different from the voltage applied to the electrode portion is applied, thereby pulling the connecting portion towards the vibrating body so that the electrode portion faces the vibrating body. [Explanation of Symbols]

[0069] 1 MEMS oscillator 10 circuit boards 10a First main surface 10b Second main surface 11 Insulating layer 12 Cavity 13 Bottom wall 20 Vibrating electrode 21 Vibrating Body 21a Main Unit 21b Deformation suppression section 22 Anchors 23 Support part 23a base 23b Tip 24 Isolation Joints 25 electrode pads 26 wiring layer 30 Fixed electrode 31 Electrode part 32 Anchors 33 Connecting part 34 Isolation Joints 35 electrode pads 36 wiring layer 40 Springs 41 Ring section 42 Flexible beam 42a Part 1 42b Part 2 50 beams 51 Protrusion 52 Insulator 60 Regulatory Department 70 Electrostatic Chuck Section 71 Beam 72 Electrode section 73 Isolation Joint 74 Isolation Joint 75 electrode pads 76 Wiring layer

Claims

1. A substrate having a first main surface and a second main surface located opposite to the first main surface, wherein a cavity recessed from the first main surface toward the second main surface is provided, A vibrating body is disposed within the cavity, extending linearly in a first direction within the plane when the first main surface is viewed from above, and vibrating in a second direction intersecting the first direction within the plane, A plurality of support parts are arranged within the cavity and at a plurality of support positions spaced apart from each other along the first direction, supporting the vibrating body from the second direction. A MEMS oscillator equipped with the following features.

2. The MEMS vibrator according to claim 1, wherein the plurality of support portions each support the vibrating body over the entire vibrating body in the thickness direction of the substrate at their respective support positions.

3. The vibrating body is The body is made of silicone, A deformation-suppressing portion is disposed within the main body and has a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the main body. The MEMS oscillator according to claim 1, comprising:

4. An electrode portion for vibrating the vibrating body is positioned facing the vibrating body in the second direction, An anchor fixed to the substrate and supporting the electrode portion, A connecting portion that connects the electrode portion and the anchor. Equipped with, The aforementioned connecting portion is A first part having a first thermal expansion coefficient, A second portion is positioned adjacent to the first portion in the second direction and has a second thermal expansion coefficient different from the first thermal expansion coefficient. It has, The MEMS vibrator according to claim 1, wherein the connecting portion is deformed by the difference between the thermal stress generated in the first portion and the thermal stress generated in the second portion, and the deformation of the connecting portion causes the distance between the vibrating body and the electrode portion to become narrower compared to before the deformation of the connecting portion.

5. The MEMS transducer according to claim 4, further comprising a restricting portion that restricts the displacement of the electrode portion by contacting the connecting portion when the electrode portion is displaced by a predetermined distance toward the vibrating body due to deformation of the connecting portion.

6. The MEMS vibrator according to claim 5, further comprising an electrostatic chuck portion positioned facing the connecting portion in the second direction, which generates an electrostatic force between itself and the connecting portion when a voltage different from the voltage applied to the electrode portion is applied, thereby pulling the connecting portion towards the vibrating body so that the electrode portion faces the vibrating body.

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