Implementation structure and inertial sensor

Abstract

The present invention provides a mounting structure comprising a vibrating body having a three-dimensional curved surface and a mounting substrate, which increases the capacitance between the detection electrode and the vibrating body while ensuring the vibration amplitude during driving of the vibrating body, and an inertial sensor using the same. [Solution] The mounting structure comprises a vibrating body 2 having a curved surface portion 21 having a hemispherical three-dimensional curved surface, and a mounting substrate 3 having a plurality of electrodes 54, 55 that are separated by a distance from the rim 23, which is the end of the curved surface portion 21. The plurality of electrodes 54, 55 are inner electrodes arranged in an inner region of the mounting substrate 3, which is a region located inside the rim 23, and are composed of a plurality of types of electrodes that differ in at least one of their shape and the gap with the rim. The inertial sensor has the above mounting structure and detects the inertial force applied to the sensor by one of the inner electrodes.

Description

【Technical Field】 【0001】 The present disclosure relates to a mounting structure in which a vibrating body having a three-dimensional curved surface is mounted on a mounting substrate and an inertial sensor using the same. 【Background Art】 【0002】 Conventionally, an inertial sensor having a mounting structure in which a vibrating body having a three-dimensional curved surface is mounted on a mounting substrate having a plurality of electrodes has been known (for example, Patent Document 1). The inertial sensor described in Patent Document 1 has a vibrating body having a substantially hemispherical three-dimensional curved surface that vibrates in a wine glass mode, and a plurality of electrodes formed on the mounting substrate and independent of each other are arranged at an equal distance from the vibrating body while being separated from the vibrating body. This is a BRG. BRG is an abbreviation for Bird-bath Resonator Gyroscope. This inertial sensor has a structure in which the Q value representing the vibration state in the vibrating body reaches 10 6 or more, so higher accuracy than before is expected. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 U.S. Patent Application Publication No. 2019 / 0094024 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In a BRG, applying a voltage to the drive electrode among multiple electrodes generates a first vibration at the end of the vibrating body. When an external angular velocity is applied in this state, the Coriolis force causes a second vibration at the end of the vibrating body that vibrates in a direction different from the first vibration, and this second vibration is detected by the detection electrode. To improve the detection accuracy of the second vibration in a BRG, it is necessary to increase the capacitance between the end of the vibrating body and the detection electrode. To further increase the capacitance between the vibrating body and the electrode in a BRG, for example, a first mounting structure can be used in which an electrode is placed on the inner side of the vibrating body, i.e., closer to the center than the end of the vibrating body, and the end of the vibrating body is sandwiched between the outer and inner electrodes. Alternatively, a second mounting structure can be considered, which has multiple electrodes placed on the inner side as described above, and does not have drive / detection electrodes placed on the outside of the end of the vibrating body. In the case of the second mounting structure, the capacitance between the vibrating body and the electrode can be increased compared to a conventional BRG, while the overall sensor can be miniaturized. For the sake of simplicity of explanation, electrodes placed inside the end of the vibrating body among the multiple electrodes on the mounting substrate will be called "inner electrodes," and electrodes placed outside the end of the vibrating body will be called "outer electrodes." 【0005】 Because the BRG vibrator has a roughly hemispherical shape, when a mounting structure with an inner electrode is used, the gap with the upper edge of the inner electrode is smallest, and the gap with the inner electrode increases as it moves downwards towards the bottom surface of the mounting substrate. In other words, in the first or second mounting structure, although the capacitance between the end of the vibrator and the inner electrode increases due to the placement of the inner electrode, this increase is suppressed due to the roughly hemispherical shape of the vibrator. 【0006】 Furthermore, the drive electrode used to drive the vibrating body among the inner electrodes of the mounting substrate needs to have a sufficiently large gap with the end of the vibrating body in order to ensure a large vibration amplitude when the vibrating body is driven. On the other hand, the detection electrode used to detect the second vibration among the inner electrodes of the mounting substrate needs to have a small gap with the end of the vibrating body in order to increase the sensitivity of the detection. 【0007】 In a mounting structure like the one provided in Patent Document 1, where a sacrificial layer is provided to temporarily connect the end of the vibrating body to the mounting substrate, and then this sacrificial layer is removed, the gap between the driving electrode and the detection electrode and the end of the vibrating body becomes the same. In such a mounting structure, if an inner electrode is used, the effect of increasing the capacitance of the detection electrode is suppressed due to the approximately hemispherical shape of the vibrating body, as described above. 【0008】 In view of the above, this disclosure aims to provide a mounting structure having a vibrating body having a three-dimensional curved surface and a mounting substrate, which increases the capacitance between the detection electrode and the vibrating body while ensuring the vibration amplitude when the vibrating body is driven, and an inertial sensor using the same. [Means for solving the problem] 【0009】 From one perspective of this disclosure, the implementation structure is: A vibrating body (2) having a curved surface portion (21) having a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, The mounting substrate (3) has a curved surface portion with the end opposite to the connection portion designated as a rim (23), and is positioned to surround the area where the connection portion is joined, and has a plurality of electrodes (54, 55) facing the rim at a distance from it. The multiple electrodes are inner electrodes located in the inner region of the mounting substrate, which is the area inside the rim, and consist of multiple types of electrodes with different shapes. 【0010】 This mounting structure ensures that the Q value representing the vibration state of the vibrating body is secured, as the vibrating body has a curved surface with a hemispherical portion and a connecting portion extending toward the inner center of the curved surface, and is bonded to the mounting substrate. Furthermore, this mounting structure has multiple electrodes positioned in the region inside the rim, which is the end of the curved surface opposite the connecting portion, and facing the rim at a distance, and these multiple electrodes are composed of multiple types of electrodes with different shapes. This mounting structure allows for the drive electrode used to drive the vibrating body and the detection electrode used to detect a second vibration of the vibrating body to be composed of different types of electrodes, while also allowing for different gaps between the drive electrode and the detection electrode and the rim. Therefore, this mounting structure ensures the vibration amplitude when the vibrating body is driven while increasing the capacitance between the detection electrode and the vibrating body. 【0011】 According to another aspect of this disclosure, the implementation structure is: A vibrating body (2) having a curved surface portion (21) having a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, The mounting substrate (3) has a curved surface portion with the end opposite to the connection portion designated as a rim (23), and is positioned to surround the area where the connection portion is joined, and has a plurality of electrodes (54, 55) facing the rim at a distance from it. The multiple electrodes are inner electrodes located in the inner region of the mounting substrate, which is the area inside the rim, and consist of multiple types of electrodes with different gaps from the rim. 【0012】 This mounting structure consists of multiple inner electrodes positioned inside the rim of the vibrating body, each with a different gap from the rim. This allows for different gaps between the drive electrode and the detection electrode. As a result, this mounting structure ensures sufficient vibration amplitude during the driving of the vibrating body while increasing the capacitance between the detection electrode and the vibrating body. 【0013】 According to another aspect of this disclosure, an inertial sensor is, A vibrating body (2) having a curved surface portion (21) with a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, A mounting substrate (3) having a plurality of electrodes (54, 55) disposed at a position surrounding the portion to which the connecting portion is joined, with an end portion of the curved surface portion opposite to the connecting portion as a rim (23), The plurality of electrodes are inner electrodes disposed in an inner region, which is a region of the mounting substrate located inside the rim, and are composed of a plurality of types of electrodes having at least one of different shapes and gaps from the rim. 【0014】 This inertial sensor includes any of the above-described mounting structures, and since the gap between the drive electrode and the rim of the vibrating body is greater than or equal to a predetermined value and the gap between the detection electrode and the rim can be narrowed, it is possible to ensure the vibration amplitude during driving of the vibrating body and increase the capacitance of the detection electrode simultaneously. 【0015】 The reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later. 【Brief Description of the Drawings】 【0016】 [Figure 1] It is a perspective view showing the inertial sensor of the first embodiment. [Figure 2] It is a view seen in the direction of the arrow from the II direction of FIG. 1. [Figure 3] It is a cross-sectional view taken along the line III-III of FIG. 2. [Figure 4] It is a cross-sectional view taken along the line IV-IV of FIG. 2. [Figure 5] It is an enlarged cross-sectional view showing the V region of FIG. 4. [Figure 6] It is a view corresponding to FIG. 5, and is an enlarged cross-sectional view showing an example when the diameter of the curved surface portion of the vibrating body is small. [Figure 7] It is an explanatory view of an arrangement example of the first inner electrode and the second inner electrode. [Figure 8]Explanatory drawing regarding the first vibration mode of the vibrating body by the first inner electrode. [Figure 9] Explanatory drawing regarding the second vibration mode of the vibrating body caused by an external force applied to the inertial sensor during driving in FIG. 8. [Figure 10A] Cross-sectional view showing the first step of electrode formation in the manufacturing process of the inertial sensor of the first embodiment. [Figure 10B] Cross-sectional view showing the step following FIG. 10A. [Figure 10C] Cross-sectional view showing the step following FIG. 10B. [Figure 10D] Cross-sectional view showing the step following FIG. 10C. [Figure 10E] Cross-sectional view showing the step following FIG. 10D. [Figure 10F] Cross-sectional view showing the step following FIG. 10E. [Figure 11] Cross-sectional view showing the second inner electrode in a modified example of the inertial sensor of the first embodiment. [Figure 12] Cross-sectional view showing the second inner electrode in the inertial sensor of the second embodiment. [Figure 13A] Cross-sectional view showing the first step of electrode formation in the manufacturing process of the inertial sensor of the second embodiment. [Figure 13B] Cross-sectional view showing the step following FIG. 13A. [Figure 13C] Cross-sectional view showing the step following FIG. 13B. [Figure 13D] Cross-sectional view showing the step following FIG. 13C. [Figure 14] Cross-sectional view showing the second inner electrode in a modified example of the inertial sensor of the second embodiment. [Figure 15] A figure corresponding to FIG. 14, which is an enlarged cross-sectional view showing an example when the diameter of the curved surface portion of the vibrating body is small. [Figure 16] Cross-sectional view showing the second inner electrode in the inertial sensor of the third embodiment. [Figure 17] A figure corresponding to FIG. 2, which is a top layout view showing the inertial sensor of the fourth embodiment. [Figure 18]This is a cross-sectional view showing the first inner electrode and the second inner electrode in the inertial sensor of the fifth embodiment. [Modes for carrying out the invention] 【0017】 The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals. 【0018】 (First Embodiment) The inertial sensor 1 of the first embodiment will now be described. 【0019】 [Basic configuration] As shown in Figures 1 and 2, the inertial sensor 1 has a mounting structure in which a vibrating body 2 that vibrates in wineglass mode is mounted on a mounting substrate 3, and is suitable for application to various devices that utilize the vibration characteristics of the vibrating body 2, such as gyro sensors such as BRGs. In this specification, the case in which the inertial sensor 1 is a BRG is described as a representative example, but the application is not limited to this. 【0020】 For the sake of explanation, as shown in Figure 1, the direction along one side of the outer casing in the planar direction of the mounting substrate 3 will be referred to as the "x direction," the direction perpendicular to the x direction in the same planar direction will be referred to as the "y direction," and the direction normal to the xy plane will be referred to as the "z direction." The x, y, and z directions in Figures 2 and onward correspond to the x, y, and z directions in Figure 1, respectively. Furthermore, in this specification, "up" refers to the direction along the z direction in the figures, meaning the side indicated by the arrow, and "down" refers to the opposite side of "up." In addition, in this specification, the view of the inertial sensor 1 or the mounting substrate 3 from the upper side in the z direction may be referred to as the "top view." 【0021】 In Figure 2, to make the configuration of the mounting substrate 3 easier to understand, a portion of the outer casing of the vibrating body 2 is shown with a dashed line, and the outer casing of the portion of the mounting substrate 3 that is covered by the vibrating body 2 when viewed from above is shown with a solid line. 【0022】 The vibrating body 2 is a three-dimensional, substantially symmetrical micro-vibrating body, as shown in Figures 3 and 4, for example, comprising a curved surface portion 21 including the outer shape of a roughly hemispherical three-dimensional curved surface, and a bottomed cylindrical connecting portion 22 extending from the apex side of the virtual hemisphere formed by the curved surface portion 21 toward the inner center of the hemisphere. In the vibrating body 2, for example, the bottom surface 22a of the recess located inside the cylindrical portion of the bottomed cylindrical connecting portion 22 is used as a suction surface for holding and transport by vacuum suction, and the surface opposite to the bottom surface 22a is a mounting surface 22b that is joined to the mounting substrate 3. In the vibrating body 2, for example, the side with the larger outer diameter is the front surface and the opposite side is the back surface, and a conductive film (not shown) is formed on at least the back surface. The vibrating body 2 can be subjected to voltage application from the mounting substrate 3 via the conductive film (not shown) formed on the mounting surface 22b. Furthermore, the vibrating body 2 has, for example, a rim 23 which is the end of the curved surface portion 21 opposite to the connecting portion 22, facing a plurality of inner electrodes 54, 55. The vibrating body 2 vibrates in a resonant mode due to the electrostatic force generated between the first inner electrode 54 and the rim 23. The vibrating body 2 has, for example, a base portion having the curved surface portion 21 and the connecting portion 22, which is made of any reflowable material such as glass or quartz, and a conductive film (not shown) which is made of a laminated film of any conductive material such as chromium or gold. 【0023】 The vibrating body 2 can be manufactured by preparing a plate made of any reflow material such as quartz, and a mold (not shown) having a bowl-shaped recess and a support column located in the center of the recess. The plate is then set in the mold, and the recess is heated and softened while the pressure is reduced, causing differential pressure deformation. The vibrating body 2 is formed by processing a thin-walled substrate made of reflow material using the above forming process, resulting in a thin-walled member with a thickness of 10 μm to 100 μm at the curved portion 21 and the connecting portion 22, which is on the order of micrometers. The vibrating body 2 has a millimeter-sized shape, for example, with a height dimension of 2.5 mm and an outer diameter of 5 mm on the surface side of the rim 23, with the height direction being along the thickness direction of the mounting substrate 3. 【0024】 For the sake of explanation, as shown in Figure 2, the position directly below the center of the connection portion 22 in a top view of the mounting substrate 3 will be referred to as "center position C". Furthermore, as indicated by the arrows in Figure 2, the circumferential direction in the xy plane with a virtual line passing through center position C along the z direction will be referred to as "substrate circumferential direction D1", and the radial direction in the xy plane with the same virtual line as the axis will be referred to as "substrate radial direction D2". Note that all directions from 0° to 360° radiating from center position C in the xy plane are substrate radial directions D2, but for clarity, only one direction is shown as a representative example in Figure 2. 【0025】 The mounting board 3 comprises a lower board 4 and an upper board 5, as shown in Figures 1 and 2, for example, and these are joined together. The manufacturing process for the mounting board 3 will be described later. 【0026】 The lower substrate 4 is a support for the upper substrate 5, and its base is made of, for example, an insulating material such as borosilicate glass. The lower substrate 4 has grooves 41 and wiring 42 formed on it. 【0027】 The groove 41 is an annular groove provided between the frame portion 51 and the plurality of inner electrodes 54 and 55, as shown in Figures 1 to 3, for example, and is formed by wet etching. The groove 41 is sized to correspond to the outer diameter of the rim 23 of the vibrating body 2, and is provided to prevent the rim 23 from contacting the mounting substrate 3 when the vibrating body 2 is mounted on the mounting substrate 3. The groove 41 may have a shape in which a part of it is recessed toward the center position C, for example, so that when viewed from above, the outer edge on the center position C side follows the outer circumference of the inner electrodes 54 and 55, and its shape and dimensions may be changed as appropriate. If the vibrating body 2 has a shape in which the mounting surface 22b of the connection portion 22 protrudes more than the rim 23, the lower substrate 4 may be configured without the groove 41. 【0028】 The wiring 42 is made of any conductive material such as aluminum, and is arranged to pass between the multiple inner electrodes 54, 55 and the outer electrode 52, and is electrically independent of these electrodes. Multiple wirings 42 are provided, and on the lower substrate 4, they straddle the groove 41, with one end connected to the frame portion 51 and the other end connected to the vibrator electrode 53, thus electrically connecting them. In Figure 2, an example is shown where the lower substrate 4 has two wirings 42, but it is not limited to this, and the number and arrangement of the wirings 42 can be changed as appropriate. 【0029】 The upper substrate 5 is made of, for example, silicon, a semiconductor material. The upper substrate 5 includes, for example, a frame portion 51, a plurality of outer electrodes 52, a vibrating electrode 53, a plurality of first inner electrodes 54, and a plurality of second inner electrodes 55. 【0030】 The frame portion 51 is formed together with the outer electrode 52, the vibrator electrode 53, the first inner electrode 54, and the second inner electrode 55 by, for example, dry etching such as DRIE on the upper substrate 5. DRIE is an abbreviation for Deep Reactive Ion Etching. The frame portion 51 is, for example, an annular shape when viewed from above, and is configured so that the connection portion 22 of the vibrator 2 can be inserted into the enclosed area. 【0031】 Multiple outer electrodes 52 are arranged in the outer region of the mounting substrate 3, which is the area outside the rim 23, facing the rim 23 of the vibrating body 2, and are arranged apart from each other along the circumferential direction D1 of the substrate. For example, an electrode film (not shown) is formed on the upper surface of the multiple outer electrodes 52 opposite to the lower substrate 4, and wires (not shown) are connected to it, so that the potential of the multiple outer electrodes 52 can be controlled by an external power supply (not shown). The upper surface is the surface of the electrode surface that faces upward in the z direction, and this is the same for the other electrodes as well. All of the multiple outer electrodes 52 are separated from the rim 23 of the vibrating body 2 by a predetermined distance, and each forms a capacitor with the vibrating body 2. Some of the multiple outer electrodes 52 are used as detection electrodes to detect capacitance, and other parts are used as driving electrodes to apply electrostatic force to the rim 23 of the vibrating body 2. The driving electrodes of the multiple outer electrodes 52 are electrically connected to a first inner electrode 54, which will be described later and is also a driving electrode, for example, via a through electrode (not shown) formed directly below it and wiring (not shown) connected thereto. Of the multiple outer electrodes 52, the detection electrode is electrically connected to a second inner electrode 55, which will be described later and is also a detection electrode, similar to the drive electrode. 【0032】 The vibrating electrode 53 is, for example, positioned in the outer region and electrically connected to a conductive film (not shown) of the vibrating body 2 via wiring 42. The vibrating electrode 53, for example, has an electrode film (not shown) on its upper surface, similar to the outer electrode 52, and is connected to an external power supply (not shown) via wires or the like connected to the electrode film. The vibrating electrode 53 is used for potential control of the vibrating body 2. For example, multiple vibrating electrode 53 may be provided, but there may be only one, and the number and arrangement can be changed as appropriate. In addition, the vibrating electrode 53 may be electrically connected to the conductive film (not shown) of the vibrating body 2 via a region surrounded by the frame portion 51 and a through electrode (not shown) formed directly below the vibrating electrode 53, similar to the inner electrodes 54 and 55, instead of wiring 42. Thus, the electrical connection structure between the vibrating electrode 53 and the vibrating body 2 can be changed as appropriate. 【0033】 Multiple first inner electrodes 54 are arranged in the inner region of the mounting substrate 3, which is the area inside the rim 23. The first inner electrodes 54 are driving electrodes for vibrating the vibrating body 2 in a first vibration mode by electrostatic force. As shown in Figure 3, the gap Gp1 between the first inner electrodes 54 and the rim 23 in the substrate radial direction D2 is set to a predetermined value or greater in order to ensure a sufficiently large vibration amplitude when driving the vibrating body 2. The multiple first inner electrodes 54 are arranged apart from each other along the substrate circumferential direction D1 and are positioned closer to the center position C than the second inner electrode 55. The multiple first inner electrodes 54 have a different shape from the second inner electrode 55 and are of a different type from the second inner electrode 55. For example, if the other surface of the first inner electrode 54 adjacent to the top surface is considered a side surface, then the multiple first inner electrodes 54 have, for example, flat top and side surfaces, and the top surface and side surfaces are perpendicular to each other. In other words, in this embodiment, the mounting substrate 3 is composed of two types of inner electrodes 54 and 55 with different shapes. 【0034】 The second inner electrodes 55, like the first inner electrodes 54, are arranged in multiples in the inner region of the mounting substrate 3. The second inner electrodes 55 are detection electrodes for detecting a second vibration mode generated by an external force when the vibrating body 2 is driven. The multiple second inner electrodes 55 are positioned further from the center position C than the first inner electrodes 54, i.e., closer to the rim 23. As shown in Figure 4, the gap Gp2 between the multiple second inner electrodes 55 and the rim 23 in the substrate radial direction D2 is smaller than the gap Gp1. As a result, the capacitance between the multiple second inner electrodes 55 and the rim 23 is improved, and consequently, the detection accuracy of the second vibration mode of the vibrating body 2 is improved. 【0035】 Furthermore, the capacitance between the detection electrode of the inertial sensor 1 and the rim 23 is the sum of the capacitance between the outer electrode 52, which is used as the detection electrode, and the rim 23, and the capacitance between the second inner electrode 55 and the rim 23. As a result, the capacitance of the inertial sensor 1 is improved compared to a configuration that has only the outer electrode 52 as the detection electrode, and the detection accuracy of the second vibration mode is also improved. 【0036】 In this embodiment, the second inner electrode 55 has a stepped portion 551 between its upper surface 55a and its opposing surface 55b, as shown in Figure 5, for example, and is shaped so as not to come into contact with the vibrating body 2 while reducing the gap Gp2 with the rim 23. As a result, even if the diameter of the curved portion 21 of the vibrating body 2 becomes smaller than expected due to manufacturing errors, the rim 23 is positioned on the stepped portion 551, as shown in Figure 6, for example, making it possible to suppress contact with the second inner electrode 55 while maintaining a narrow gap. 【0037】 The first inner electrode 54 and the second inner electrode 55 are arranged alternately along the substrate circumferential direction D1, as shown in Figure 7, for example, and are electrically independent of each other. The first inner electrode 54 is positioned such that, for example, each direction extending outward from the center position C along the substrate radial direction D2 in the xy plane is defined as an orientation from 0 to 360 degrees, and the adjacent second inner electrode 55 is positioned at a position shifted by 45 degrees in the orientation. In other words, the first inner electrode 54 and the second inner electrode 55 are positioned with their orientations shifted by 45 degrees from each other when viewed from above. Specifically, the angle between the virtual line VL1 passing through the center position and center position C of the substrate circumferential direction D1 of the first inner electrode 54 and the virtual line VL2 passing through the center position and center position C of the substrate circumferential direction D1 of the second inner electrode 55 adjacent to the first inner electrode 54 is 45 degrees. In this case, as shown by the dashed line in Figure 8, the vibrating body 2 vibrates in a first vibration mode due to the electrostatic force from the first inner electrode 54, with the outer rim 23 vibrating in a first vibration mode when viewed from above. Then, as shown by the dashed line in Figure 9, when an inertial force is applied to the inertial sensor 1 by an external force while the vibrating body 2 is driven in the first vibration mode, a second vibration mode is generated in a top view, with the orientation shifted by 45 degrees from the first vibration mode. By detecting this second vibration mode with the second inner electrode 55, which is positioned with an orientation shifted by 45 degrees from the first inner electrode 54, the detection accuracy of the second vibration mode can be further improved. 【0038】 The first inner electrode 54 and the second inner electrode 55 can be controlled to a desired potential by applying a voltage to the outer electrode 52, which is connected to them, for example, via through electrodes and wiring (not shown). For example, four of each of the first inner electrode 54 and the second inner electrode 55 are arranged, and their length in the circumferential direction D1 of the substrate is greater than that of the outer electrode 52, but the number and dimensions can be changed as appropriate. Here, the case in which four of each of the first inner electrode 54 and the second inner electrode 55 are arranged will be described as a representative example. 【0039】 Each of the multiple first inner electrodes 54 is electrically connected to one outer electrode 52 positioned, for example, at a 90-degree azimuth relative to the first inner electrode 54 when viewed from above. Each of the multiple second inner electrodes 55 is electrically connected to one outer electrode 52 positioned, for example, at a 90-degree azimuth relative to the second inner electrode 55 when viewed from above. Specifically, one second inner electrode 55 is electrically connected to another second inner electrode 55 positioned at a 180-degree azimuth relative to that first second inner electrode 55, and two outer electrodes 52 positioned at 90-degree azimuth relative to these two second inner electrodes 55, for a total of four connections. Similarly, the remaining two second inner electrodes 55 positioned at 90-degree azimuth relative to the two second inner electrodes 55 are electrically connected to the other two outer electrodes 52. Furthermore, electrodes positioned at 90-degree azimuth relative to each other among the multiple second inner electrodes 55 are electrically independent because they have different phases. 【0040】 The bonding material 6 is composed of any conductive bonding material, such as sintered silver or gold-tin. The bonding material 6 only needs to be a material that can bond to a conductive film (not shown) formed on at least the back surface of the vibrating body 2, and its constituent materials can be changed as appropriate. 【0041】 The above describes the basic configuration of the inertial sensor 1 of this embodiment. In Figure 2 and other figures, an example is shown in which the inertial sensor 1 has 16 outer electrodes 52, 4 first inner electrodes 54, and 4 second inner electrodes 55, but the number and dimensions of these electrodes can be changed as appropriate. 【0042】 [Method for manufacturing inertial sensors] Next, the manufacturing method of the inertial sensor 1 of this embodiment will be described. Since the formation of the vibrating body 2 and the joining of the vibrating body 2 to the mounting substrate 3 are known methods, the process of forming the first inner electrode 54 and the second inner electrode 55 will be mainly described here. Figures 10A to 10F, which will be described later, are cross-sectional views taken along line XX in Figure 2. 【0043】 First, as shown in Figure 10A, a bonded substrate is prepared in which a lower substrate 4 with grooves 41 formed thereon is joined to an upper substrate 5, and a protective layer 100 is formed to cover the upper substrate 5. The protective layer 100 functions as a hard mask in the etching process of the upper substrate 5, which will be described later, and is composed of an oxide film or a metal film. For example, in the case of an oxide film, the protective layer 100 is composed of a silicon oxide film or the like and is formed by CVD (Chemical Vapor Deposition) or the like. For example, in the case of a metal film, the protective layer 100 is composed of a titanium nitride film or the like and is formed by sputtering or the like. The protective layer 100 only needs to function as a hard mask, and the material and film thickness can be changed as appropriate. 【0044】 The lower substrate 4 is made of, for example, an insulating material such as borosilicate glass. A resist film with a patterned shape is formed on it by photolithography etching, then grooves 41 are formed by wet etching, and subsequently, wiring 42 is formed by sputtering. The upper substrate 5 is made of, for example, conductive low-resistance silicon and is joined to the side of the lower substrate 4 on which the grooves 41 and wiring 42 are formed by anodic bonding. 【0045】 Next, as shown in Figure 10B, a patterned resist film 110 is formed on the protective layer 100, for example, by photolithography etching. For the resist film 110, a known photoresist is used. The resist film 110 is formed by a coating method such as spin coating, and after exposure treatment, the unwanted parts are removed with a stripping solution to obtain the desired pattern shape. The areas where the resist film 110 remains are the regions of the upper substrate 5 where the frame portion 51, outer electrode 52, vibrator electrode 53, first inner electrode 54, and second inner electrode 55 are to be formed. In addition, the resist film 110 is removed from the region of the second inner electrode 55 where the stepped portion 551 is to be formed. 【0046】 Next, for example, the portion of the protective layer 100 exposed from the resist film 110 is removed by wet etching, and then the resist film 110 is removed with a stripping solution. As a result, the bonded substrate is in a state where the area of ​​the upper substrate 5 to be etched is exposed from the protective layer 100, as shown in Figure 10C. 【0047】 Subsequently, a photoresist is deposited to cover the bonding substrate using a method similar to that used for the resist film 110, and a patterned resist film 120 covering the protective layer 100 and a portion of the bonding substrate is formed by photolithography etching, as shown in Figure 10D. The resist film 120 has a patterned shape that covers the protective layer 100 and the portion of the bonding substrate where the stepped section 551 is to be formed. 【0048】 Then, trench etching is performed on the upper substrate 5 using DRIE or the like until the lower substrate 4 is partially exposed, forming the frame portion 51, multiple outer electrodes 52, vibrator electrode 53, first inner electrode 54, and part of the second inner electrode 55. After trench etching, for example, the resist film 120 is removed with a stripping solution, and the bonded substrate is in the state shown in Figure 10E. 【0049】 Next, for example, trench etching is performed on the portion of the upper substrate 5 exposed from the protective layer 100 using DRIE or the like, and partial removal is performed to a predetermined depth without reaching the lower substrate 4. After that, for example, by removing the protective layer 100 by wet etching, the bonded substrate will be in a state where it has a second inner electrode 55 having a stepped portion 551, as shown in Figure 10F. 【0050】 The above describes the basic formation process for the first inner electrode 54 and the second inner electrode 55. 【0051】 According to this embodiment, the inertial sensor 1 has a mounting structure in which a vibrating body 2 having a curved surface portion 21 with a hemispherical portion and a connecting portion 22 is bonded to a mounting substrate 3, and a Q value representing the vibration state of the vibrating body 2 is ensured. The mounting substrate 3 is arranged in a region inside the rim 23, which is the end of the curved surface portion 21 opposite to the connecting portion 22, and has a plurality of first inner electrodes 54 and second inner electrodes 55 that are separated from the rim 23 by a distance. The first inner electrodes 54 are drive electrodes used to drive the vibrating body 2. The second inner electrodes 55 are electrodes of a different shape from the first inner electrodes 54, and are detection electrodes for the second vibration mode of the vibrating body 2, and have a smaller gap with the rim 23 than the first inner electrodes 54. Therefore, this inertial sensor 1 has a mounting structure that increases the capacitance between the detection electrode and the vibrating body while ensuring the vibration amplitude when the vibrating body 2 is driven, and the effect of improving the detection accuracy of inertial force applied to the sensor from the outside is obtained. 【0052】 Furthermore, the inertial sensor 1 has a second inner electrode 55, which serves as the detection electrode, with a stepped portion 551 and a structure in which the end facing the rim 23 is shaved off, so that the second inner electrode 55 is positioned closer to the rim 23 of the vibrating body 2. As a result, the inertial sensor 1 can achieve the effect of increasing capacitance due to the narrowing of the gap Gp2, and consequently improving the accuracy of detecting the second vibration mode of the vibrating body 2. 【0053】 (modified version) The inertial sensor 1 may have its step height changed, for example, as shown in Figure 11, in the step height of the step height 551 of the second inner electrode 55. When the step height of the step height 551 is n (n: an integer of 2 or more), the step height 551 of this modified example can be formed by repeating the series of steps shown in Figures 10A to 10F n times. 【0054】 This modified version also provides an inertial sensor 1 with an implementation structure that achieves the same effects as the first embodiment described above. Furthermore, this modified version allows the number of steps in the staircase section 551 to be three or more, bringing the vibrating body 2 closer to the second inner electrode 55 and reducing the gap Gp2, thereby improving the accuracy of detecting the second vibration mode of the vibrating body 2 in the inertial sensor 1. 【0055】 (Second Embodiment) The inertial sensor 1 of the second embodiment differs from the first embodiment in that the shape of the second inner electrode 55 is changed, as shown in Figure 12, for example. This embodiment will mainly describe this difference. 【0056】 In this embodiment, as shown in Figure 12, the second inner electrode 55 has a tapered portion 552 between its upper surface 55a and its opposing surface 55b, which is inclined such that the width of the second inner electrode 55 in the substrate radial direction D2 increases towards the lower substrate 4. The tapered portion 552 is, for example, a single flat surface and is inclined with a predetermined inclination with respect to the z direction. The second inner electrode 55 has a tapered portion 552 so that when the vibrating body 2 is joined to the mounting substrate 3 with the substantially hemispherical curved portion 21 close to it, contact with the vibrating body 2 is prevented, while the gap Gp2 with the rim 23 is kept below a predetermined level. 【0057】 The second inner electrode 55 of this embodiment is formed by the following process. Note that Figures 13A to 13D, described later, show a portion of the same cross-section as in Figure 10A, and the first inner electrode 54, which is the same as in the first embodiment, is omitted. Furthermore, the differences from the first embodiment will be mainly explained here. 【0058】 In this embodiment, as shown in Figure 13A, a patterned resist film 110 is formed on the protective layer 100 deposited on the bonding substrate, for example, by photolithography etching. In this step, the resist film 110 is left in the areas of the upper substrate 5 where the frame portion 51, outer electrode 52, vibrator electrode 53, and first inner electrode 54 are to be formed, while the resist film 110 is removed from the other areas. 【0059】 Next, for example, the portion of the protective layer 100 exposed from the resist film 110 is removed by wet etching, and then the resist film 110 is removed with a stripping solution. As a result, the bonded substrate is in a state where the area of ​​the upper substrate 5 to be etched is exposed from the protective layer 100, as shown in Figure 13B. 【0060】 Next, a photoresist is deposited to cover the bonding substrate using a method similar to that used for the resist film 110, and a patterned resist film 120 covering the protective layer 100 and a portion of the bonding substrate is formed by photolithography etching, as shown in Figure 13C. The resist film 120 has a patterned shape that covers the protective layer 100 and the portion of the bonding substrate where the second inner electrode 55 is to be formed. Furthermore, by adjusting the exposure conditions in the photolithography process, the edges of the resist film 120, including the portion located where the tapered portion 552 is to be formed, are made into tapered surfaces 121. 【0061】 Subsequently, trench etching is performed on the upper substrate 5 using DRIE or the like until the lower substrate 4 is partially exposed, forming the frame portion 51, multiple outer electrodes 52, vibrator electrode 53, first inner electrode 54, and second inner electrode 55. At this time, the portion of the lower substrate 4 located directly below the tapered surface 121 of the resist film 120 is partially removed by the trench etching described above, forming a tapered portion 552. After this trench etching, the bonded substrate is brought to the state shown in Figure 13D by removing the resist film 120 with a stripping solution, for example. Then, by removing the protective layer 100 by wet etching, for example, the bonded substrate becomes equipped with a second inner electrode 55 having a tapered portion 552. In this embodiment, the end of the second inner electrode 55 facing the connection portion 22 of the vibrator 2 also has a tapered shape similar to the tapered portion 552, but this does not cause any particular problems. Furthermore, as shown in Figure 13C, the edges of the resist film 120 deposited on the protective layer 100 also have a tapered surface 121. However, the portion of the upper substrate 5 located directly beneath it is protected by the protective layer 100 and therefore does not have a tapered shape. 【0062】 This embodiment also provides an inertial sensor 1 with an implementation structure that provides the same effects as the first embodiment described above. 【0063】 (modified version) The inertial sensor 1 may have a tapered portion 552 on the opposing surface 55b, as shown in Figure 14, for example. Furthermore, in the inertial sensor 1 according to this modified example, as shown in Figure 15, even if the diameter of the curved portion 21 of the vibrating body 2 along the substrate radial direction D2 becomes smaller than expected due to manufacturing errors, etc., the rim 23 of the vibrating body 2 will be positioned on the tapered portion 552 of the second inner electrode 55. The same applies to the inertial sensor 1 of the second embodiment described above. 【0064】 This modified version also provides an inertial sensor 1 with an implementation structure that provides the same effects as the second embodiment described above. 【0065】 (Third embodiment) The inertial sensor 1 of the third embodiment differs from the first embodiment in that, as shown in Figure 16, for example, the opposing surface 55b of the second inner electrode 55 has a curved shape. This embodiment will mainly explain this difference. 【0066】 In this embodiment, the second inner electrode 55 has a curved surface such that the width of the second inner electrode 55 in the substrate radial direction D2 increases as the opposing surface 55b is directed downward in the z direction. The opposing surface 55b of the second inner electrode 55 has a degree of curvature such that, for example, the gap with the vibrating body 2 in the substrate radial direction D2 is narrower towards the upper surface 55a and wider towards the lower substrate 4. In other words, the opposing surface 55b has a different degree of curvature from the curved surface of the part of the vibrating body 2 that faces the opposing surface along the substrate radial direction D2. Furthermore, from the viewpoint of increasing capacitance and improving detection accuracy, it is preferable that the degree of curvature of the opposing surface 55b be adjusted so that the gap Gp2 with the rim 23 is a gap that is in line with the vibration amplitude of the vibrating body 2. The curved shape of the opposing surface 55b can be formed by adjusting the exposure conditions to create a curved shape at the end face of the resist film 120 in the process shown in Figure 13C of the second embodiment's formation process for the second inner electrode 55. 【0067】 This embodiment also provides an inertial sensor 1 with an implementation structure that provides the same effects as the first embodiment described above. 【0068】 (Fourth Embodiment) The inertial sensor 1 of the fourth embodiment differs from the first embodiment in that, as shown in Figure 17, for example, it does not have an outer electrode 52 and the planar size of the mounting substrate 3 is smaller. This embodiment will mainly explain these differences. 【0069】 In this embodiment, the mounting substrate 3 has a vibrating electrode 53, a first inner electrode 54, and a second inner electrode 55, but does not have a plurality of outer electrodes 52. The mounting substrate 3 has a smaller planar size because it does not have the outer electrodes 52. As a result, the inertial sensor 1 of this embodiment has a smaller planar size in the xy plane compared to the above embodiments. In this embodiment, the first inner electrode 54 and the second inner electrode 55 may be formed on the surface of the lower substrate 4, for example, similar to the vibrating body 2, and connected to an external power supply (not shown) via wiring (not shown) that extends to the outside of the groove 41. 【0070】 According to this embodiment, the inertial sensor 1 is formed by bonding a vibrating body 2 to a mounting substrate 3 having a second inner electrode 55 positioned at a location where the gap between the vibrating body 2 and the rim 23 is narrow, and a first inner electrode 54 positioned at a location where the gap between the vibrating body 2 and the rim 23 is secured to a predetermined or greater extent. Because this inertial sensor 1 has the second inner electrode 55, the gap between the rim 23 and the detection electrode is narrower than in conventional designs, thus ensuring the vibration amplitude during the driving of the vibrating body 2 while increasing the capacitance between the detection electrode and the vibrating body 2. 【0071】 (Fifth embodiment) The inertial sensor 1 of the fifth embodiment differs from the first embodiment in that the first inner electrode 54 and the second inner electrode 55 have the same shape, as shown in Figure 18, for example. This embodiment will mainly explain this difference. Note that Figure 18 shows a cross-section corresponding to Figure 10F, and for ease of viewing, only the portion of the rim 23 of the vibrating body 2 that faces the first inner electrode 54 and the second inner electrode 55 is shown. 【0072】 In this embodiment, the second inner electrode 55 has, for example, a flat surface 55b facing it along the z-direction. The second inner electrode 55 has the same shape as the first inner electrode 54 and is the same type of electrode as the first inner electrode 54, except for the gap with the rim 23 in the substrate radial direction D2. In other words, in this embodiment, the mounting substrate 3 is composed of multiple inner electrodes of the same shape and type, and the gap with the rim 23 is different for the driving electrode and the detection electrode when the vibrating body 2 is attached. 【0073】 According to this embodiment, the mounting substrate 3 has a first inner electrode 54 and a second inner electrode 55, and the inertial sensor 1 has a mounting structure that achieves both securing the vibration amplitude in the first vibration mode of the vibrating body 2 and improving detection accuracy by increasing the capacitance between the detection electrode and the rim 23. 【0074】 (Other embodiments) This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms including one, more, or less of those elements, fall within the scope and concept of this disclosure. 【0075】 It goes without saying that, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated to be particularly essential or unless it is clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc., of the components are mentioned, the embodiment is not limited to those shapes, positional relationships, etc., unless explicitly stated or unless it is clearly limited to a specific shape, positional relationship, etc., in principle. [Explanation of symbols] 【0076】 2...Vibrating body, 21...Curved surface, 22...Connection part, 23...Rim, 3...Mounting substrate, 54...First inner electrode, 55...Second inner electrode, 55a...Upper surface (of the second inner electrode), 55b...Opposite surface (of the second inner electrode), 551...Stepped section, 552...Tapered section, C...Center position (of the mounting substrate), D1...Circumferential direction of the substrate, D2...Radial direction of the substrate

Claims

[Claim 1] Implementation structure, A vibrating body (2) having a curved surface portion (21) having a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, The mounting substrate (3) comprises a curved surface portion with the end opposite to the connecting portion designated as a rim (23), and a plurality of electrodes (54, 55) positioned to surround the area where the connecting portion is joined, and facing the rim at a distance from it. The mounting structure comprises multiple electrodes, each being an inner electrode located in an inner region of the mounting substrate, which is a region located inside the rim, and consisting of multiple types of electrodes with different shapes. [Claim 2] Implementation structure, A vibrating body (2) having a curved surface portion (21) having a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, The mounting substrate (3) comprises a curved surface portion with the end opposite to the connecting portion designated as a rim (23), and a plurality of electrodes (54, 55) positioned to surround the area where the connecting portion is joined, and facing the rim at a distance from it. A mounting structure in which the plurality of electrodes are inner electrodes located in an inner region of the mounting substrate, which is a region located inside the rim, and which consist of a plurality of types of electrodes with different gaps from the rim. [Claim 3] The mounting structure according to claim 1 or 2, wherein at least one electrode constituting the plurality of electrodes has a stepped portion (551) in the shape of a step facing the vibrating body. [Claim 4] The mounting structure according to claim 1 or 2, wherein at least one electrode constituting the plurality of electrodes has a tapered portion (552) that faces the vibrating body. [Claim 5] The direction along the thickness direction of the mounting substrate, with the direction from the connection portion toward the curved portion being defined as "up" and the direction opposite to "up" being defined as "down", the surface of the plurality of electrodes facing upward being defined as the upper surface (55a), and the surface of the plurality of electrodes adjacent to the upper surface and facing the rim being defined as the opposing surface (55b), The mounting structure according to claim 1 or 2, wherein at least one electrode constituting the plurality of electrodes has a curved shape on its opposing surface, with the upper side having a smaller gap with the rim than the lower side. [Claim 6] The mounting structure according to claim 3, wherein the rim is positioned on the stepped portion, with the direction along the thickness direction of the mounting substrate and the direction from the connection portion toward the curved portion being considered upward. [Claim 7] The position on the mounting substrate that coincides with the center of the connection portion is defined as the center position (C), the circumferential direction along the plane formed by the mounting substrate with the center position as the axis is defined as the substrate circumferential direction (D1), and the radial direction with the center position as the axis is defined as the substrate radial direction (D2). The plurality of electrodes are composed of two types of electrodes with different gaps with respect to the rim in the radial direction of the substrate, and these two types of electrodes are arranged alternately along the circumferential direction of the substrate. The mounting structure according to claim 1 or 2, wherein the two types of electrodes are arranged in the plane with a direction that extends outward from the center position along the radial direction of the substrate, and the direction is set at 45-degree intervals along the direction. [Claim 8] It is an inertial sensor, A vibrating body (2) having a curved surface portion (21) having a hemispherical three-dimensional curved surface, and a connecting portion (22) extending from the curved surface portion to the inner center of the curved surface portion, The mounting substrate (3) comprises a curved surface portion with the end opposite to the connecting portion designated as a rim (23), and a plurality of electrodes (54, 55) positioned to surround the area where the connecting portion is joined, and facing the rim at a distance from it. An inertial sensor comprising multiple electrodes, each being an inner electrode positioned in an inner region of the mounting substrate, which is a region located inside the rim, and consisting of multiple types of electrodes, each differing in shape and at least one of the gap between the electrodes and the rim.

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