Inertial Sensors

Abstract

The micro-vibrator (2) includes a curved surface (21), a recess (22) recessed from the curved surface, a bottom surface protrusion (23) protruding from the bottom surface (22b) of the recess, and a through hole (24) in the bottom surface protrusion. The mounting substrate (3) has a positioning recess (43) for the bottom surface protrusion to be inserted therein, and an electrode portion (53) surrounding the inner frame portion. The bonding member (52) is located in the positioning recess and bonds the bottom surface protrusion to the mounting substrate. The bottom surface contacts the area of ​​the mounting substrate surrounding the positioning recess. The bottom surface protrusion has a tip end surface (23b) spaced a certain distance from the positioning recess. The bonding member at least partially enters the through hole and is electrically connected to the conductive layer.

Description

Technical Field

[0001] The invention relates to an inertial sensor, which comprises a micro-vibration body with a three-dimensional curved surface. Background Art

[0002] In recent years, an automobile autonomous driving system has been developed. Such a system requires a highly accurate self-positioning estimation technology. For example, to achieve so-called Level 3 autonomous driving, a self-positioning estimation system equipped with a global navigation satellite system (GNSS) and an inertial measurement unit (IMU) has been developed. The IMU is, for example, a 6-axis inertial force sensor composed of a 3-axis gyro sensor and a 3-axis acceleration sensor. In order to achieve Level 4 or higher autonomous operation, an IMU with higher accuracy than currently available is required.

[0003] As a gyro sensor for realizing such a high-sensitivity IMU, for example, a BRG (Bird-bath resonator gyro) is considered. The BRG includes a micro-vibrator having a three-dimensional curved surface, which vibrates in a wine glass mode and is mounted on a mounting substrate (for example, Patent Document 1). The micro-vibrator has a gyroscopic property of up to 10 6 Or higher Q factor indicating the vibration state. Therefore, it is expected that this micro-vibrator can produce higher sensitivity than previous structures.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent document 1: US2019 / 0094024A1. Summary of the invention

[0007] In order to achieve high precision of the inertial sensor using this micro-vibrator, the reduction of the Q factor of the micro-vibrator must be suppressed. For example, according to a paper document by T.Nagorney of the University of Michigan in 2018, it has been found that the reduction of the Q factor of this micro-vibrator is due to, for example, the film formation state of the electrode film on the surface, such as the large coverage area of ​​the substrate material by the electrode film. In addition, when a thin substrate (for example, quartz with a thickness of tens of microns) or an electrode film formed on the surface is scratched or peeled off, the Q factor of the micro-vibrator is reduced. Therefore, in order to suppress the reduction of the Q factor, during the installation process, it is necessary to handle the micro-vibrator without scratching the mounting plate, while improving the film formation state of the electrode film.

[0008] The BRG described in Patent Document 1 is manufactured so that a moving fixture for positioning a micro-vibration body is formed as a part of a mounting plate. In addition, the micro-vibration body is mounted on the mounting plate, and the position of the micro-vibration body is adjusted relative to the moving fixture. In addition, the micro-vibration body is joined to the mounting plate by a joining member. Thereafter, a part of the moving fixture in the mounting plate is released from the mounting plate by a process such as etching and removed.

[0009] However, although this method can ensure the accuracy of positioning the micro-vibrator on the mounting plate, there are many steps and the manufacturing cost may increase. In addition, in the micro-vibrator used for the BRG, the electrode film is formed on the entire front surface and the rear surface, and the film-forming state of the electrode film is not preferred from the perspective of suppressing the reduction of the Q factor.

[0010] In view of the above situation, an object of the present invention is to provide an inertial sensor having an electrode membrane structure of a micro-vibrator, which is constructed to vibrate in a wine glass mode and is convenient for positioning the micro-vibrator relative to a mounting plate with high precision while suppressing the reduction of the Q factor.

[0011] According to one aspect of the present invention, an inertial sensor includes a micro-vibration body, which is a thin-walled member having a front surface and a rear surface, wherein the front surface is a surface on a side having a large outer diameter, and the rear surface is a surface opposite to the front surface. The micro-vibration body includes a curved portion having an annular curved surface, a recessed portion recessed from the curved portion to the rear surface side, a bottom surface protrusion protruding from the bottom surface of the recess on the rear surface side, a through hole located in the bottom surface protrusion and connecting the front surface with the rear surface, and a conductive layer covering at least a portion of the front surface. The inertial sensor also includes a mounting substrate, wherein the mounting substrate includes a lower substrate and an upper substrate joined to each other, the lower substrate having a positioning recess for inserting the bottom surface protrusion of the micro-vibration body, and the upper substrate including a frame portion having a frame shape and surrounding the positioning recess, and a plurality of electrode portions, wherein the plurality of electrode portions are separated from each other and surround the inner frame portion. The inertial sensor further includes a bonding member, which is arranged in the positioning recess and bonds the bottom surface protrusion of the micro-vibration body to the mounting substrate. The curved surface of the micro-vibration body is hollow. The bottom surface contacts the region of the mounting substrate surrounding the positioning recess. The tip end of the bottom surface protrusion has a tip end surface on the side opposite to the bottom surface. The positioning recess is spaced a certain distance from the tip end surface. The engaging member at least partially enters the through hole and is electrically connected to the conductive layer.

[0012] According to this, the inertial sensor includes a micro-vibration body having a three-dimensional curved surface, a recessed portion recessed from the three-dimensional curved surface, and a bottom surface protrusion protruding from the bottom surface of the recess. In addition, the protrusion of the bottom surface of the micro-vibration body is inserted into the positioning recess of the mounting plate. The inertial sensor is positioned by inserting the bottom surface protrusion of the micro-vibration body into the positioning recess of the mounting plate. Therefore, the inertial sensor has a structure in which the positioning of the micro-vibration body relative to the mounting plate is simple and highly accurate.

[0013] In addition, in the inertial sensor, the micro-vibrator has a through hole in the bottom surface protrusion and a conductive layer covering the front surface. In addition, a part of the bonding member enters the through hole and is electrically connected to the conductive layer. Therefore, it is not necessary to set an electrode film on the rear surface of the micro-vibrator. Therefore, the coverage area of ​​the substrate of the micro-vibrator covered by the conductive layer is reduced, and the Q factor of the micro-vibrator is improved.

[0014] Therefore, in this inertial sensor, the micro-vibration body can be easily positioned with respect to the mounting plate with high accuracy, and the vibration Q factor is high and the structural accuracy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the accompanying drawings:

[0016] Figure 1 is a top view showing an inertial sensor according to one embodiment.

[0017] Figure 2 is a perspective view showing a micro-vibrator used in the inertial sensor.

[0018] Figure 3 is shown along Figure 2 A cross-sectional view of the cross-sectional structure taken along line III-III in FIG.

[0019] Figure 4A 1 is a view showing a step of preparing a member in the step of forming a micro-vibration body.

[0020] Figure 4B It is shown Figure 4A A view of step after step.

[0021] Figure 4C It is shown Figure 4B A view of step after step.

[0022] Figure 4D It is shown Figure 4C A view of step after step.

[0023] Figure 4E It is shown Figure 4D A view of step after step.

[0024] Figure 4F 2 is a view showing another example method of forming a micro-vibration body and showing a step of forming a conductive layer.

[0025] Figure 4G It shows Figure 4F A view of step after step.

[0026] Figure 5 It is shown Figure 2 A top view of a mounting substrate on which a micro-vibrator is mounted.

[0027] Figure 6 is shown along Figure 5 A cross-sectional view of the cross-sectional structure taken along line VI-VI in FIG.

[0028] Figure 7 is shown along Figure 5 A cross-sectional view of the cross-sectional structure taken along line VII-VII in FIG.

[0029] Figure 8 is shown along Figure 1 A cross-sectional view of the cross-sectional structure taken along line VIII-VIII in FIG.

[0030] Fig. 9 is shown along Figure 1 A cross-sectional view of a cross-sectional structure taken along line IX-IX in FIG.

[0031] Fig. 10A is shown along Fig. 9 A cross-sectional view of a cross-sectional structure taken along line XA-XA in FIG.

[0032] Fig. 10B is with Fig. 10A The corresponding view is an enlarged cross-sectional view showing another example of filling of the engagement member.

[0033] Fig.11A 1 is a view showing a step of mounting a micro-vibrator in manufacturing the inertial sensor, and is a view showing a step of preparing a component.

[0034] Fig. 11B It is shown Fig.11A A view of step after step.

[0035] Fig. 11C It is shown Fig. 11B A view of step after step.

[0036] Fig.11D It is shown Fig. 11C A view of step after step.

[0037] Fig.11E It is shown Fig.11D A view of step after step.

[0038] Fig.12 1 is a cross-sectional view showing another example of the shape of the bonding portion between the microvibrator and the mounting substrate.

[0039] Fig.13 1 is a cross-sectional view showing another example of another shape of the bonding portion between the microvibrator and the mounting substrate.

[0040] Fig.14 1 is a cross-sectional view showing another example of another shape of the bonding portion between the microvibrator and the mounting substrate.

[0041] Fig.15 is a perspective view showing another example of forming a conductive layer in a micro-vibrator. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, the same reference numerals are assigned to components that are identical or equivalent to each other for description.

[0043] (Example)

[0044] Reference Figures 1 to 10B An inertial sensor 1 according to one embodiment is described.

[0045] exist Figure 2 In order to facilitate understanding of the structure of the micro-vibrator 2 described later, the outer shell of the micro-vibrator 2 is Figure 2 The portion that is not visible from the angle shown is shown with a dotted line.

[0046] For ease of explanation, the following Figure 1 As shown, the direction along the left-right direction in the view is called the "x direction", the direction orthogonal to the x direction in the view is called the "y direction", and the normal direction relative to the xy plane is called the "z direction". Figure 3 The x, y and z directions in the views of the subsequent figures correspond to Figure 1 In addition, in this specification, "up" means a direction along the z direction in the drawing, and means a direction along the arrow, and "down" means a direction opposite to the up direction. In addition, in this specification, for example, Figure 1 As shown, the state in which the inertial sensor 1 or the mounting substrate 3 is viewed from the upper side in the z direction can be referred to as a “top view”.

[0047] (Basic structure)

[0048] like Figure 1As shown, the inertial sensor 1 includes, for example, a micro-vibration body 2 and a mounting substrate 3. A portion of the micro-vibration body 2 is bonded to the mounting substrate 3. The inertial sensor 1 is configured to detect an angular velocity applied to the inertial sensor 1 based on a change in capacitance between the micro-vibration body 2 and a plurality of electrode portions 53 of the mounting substrate 3 to be described later, the micro-vibration body 2 being thin-walled and configured to vibrate in a wine glass mode. The inertial sensor 1 is, for example, a gyro sensor having a BRG structure, and may be suitable for applications to be mounted on a vehicle such as a car, however, the device may also be applied to other applications.

[0049] For example, Figure 2 As shown, the micro-vibrator 2 includes a curved portion 21 having an outer shape of a substantially hemispherical three-dimensional curved surface, a concave portion 22 that is concave from the top side of the substantially hemispherical curved portion 21 toward the center side of the hemispherical shape, and a bottom surface protrusion 23 that protrudes from the concave portion 22 to be further concave toward the center. In the micro-vibrator 2, for example, the curved portion 21 has a bowl-shaped three-dimensional curved surface. The micro-vibrator 2 shows 10 5 The end of the curved portion 21 opposite to the recessed portion 22 is an edge 211. The edge 211 has, for example, a substantially tubular shape. The microvibrator 2 is mounted on the mounting substrate 3 so that the front surface 2a of the edge 211 faces the plurality of electrode portions 53 of the mounting substrate 3 to be described later, and so that the plurality of electrode portions 53 are evenly spaced between them.

[0050] For example, Figure 3 As shown, the micro-vibration body 2 has a front surface 2a with a larger outer diameter, and a rear surface 2b on the opposite side of the front surface 2a. On the rear surface 2b side, the bottom surface protrusion 23 protrudes from the bottom surface 22b of the recess 22. That is, the shape of the micro-vibration body 2 is such that the recess 22 is a first recess protruding from the curved surface 21 when viewed from the rear surface 2b, and the bottom surface protrusion 23 protruding from the tip of the recess 22 is a second recess. In the micro-vibration body 2, the outer diameter of the bottom surface protrusion 23 on the bottom surface 2b side is smaller than the outer diameter of the recess 22. In the micro-vibration body 2, the bottom surface protrusion 23 is a joint portion engaged with the mounting substrate 3. The micro-vibration body 2 is such a part in a hollow state: when the micro-vibration body 2 is mounted on the mounting substrate 3, the curved surface 21 including the edge 211 does not contact other components. The micro-vibration body 2 has such a structure: when mounted on the mounting substrate 3, the hollow edge 211 is configured to vibrate in a wine glass mode.

[0051] The micro-vibrator 2 has a through hole 24, which connects the front surface 2a to the rear surface 2b, for example, at the bottom of the bottom surface protrusion 23 when viewed from the front surface 2a, that is, at the tip when viewed from the rear surface 2b. For example, the entire front surface 2a of the micro-vibrator 2 is covered by the conductive layer 25. On the other hand, the rear surface 2b of the micro-vibrator 2 is not formed with the conductive layer 25, and its thin base material is exposed.

[0052] The conductive layer 25 is composed of, for example, but not limited to, a laminated film of a conductive material (such as Cr (chromium) or Ti (titanium) and Au (gold) or Pt (platinum) from the substrate side. The conductive layer 25 is used as an electrode film. The conductive layer 25 is formed as a thin film on the front surface 2a of the micro-vibration body 2 by a vacuum film-forming method such as sputtering or thin film deposition. On the other hand, the conductive layer 25 is not formed on the rear surface 2b, and therefore, in the micro-vibration body 2, the reduction of the vibration Q factor is suppressed compared to the case where an electrode film is formed on both the front surface and the rear surface. In the present embodiment, the conductive layer 25 covers the entire wall surface of the bottom protrusion 23 including the inner wall of the through hole 24 on the front surface 2a side. When the bonding member 52 enters the through hole 24 and solidifies, the conductive layer 25 is constructed to be electrically connected to the bonding member 52.

[0053] The protruding dimension of the bottom surface protrusion 23 on the rear surface 2b side is defined as "the height h1 of the bottom surface protrusion 23". The height h1 is sized so that the surface of the tip of the bottom surface protrusion 23 does not contact the mounting substrate 3. In addition, the micro-vibrator 2 has a structure in which the bottom surface protrusion 23 is inserted into the positioning recess 43 of the mounting substrate 3 (this will be described later) so that the micro-vibrator 2 can be easily and highly accurately positioned relative to the mounting substrate 3. In the micro-vibrator 2, the bottom surface 22b of the recess 22 is an abutment portion that abuts on the area of ​​the mounting substrate 3 surrounding the positioning recess 43 when the micro-vibrator is mounted on the mounting substrate 3. The details of this structure will be introduced later.

[0054] The micro-vibrator 2 has a through hole 24 formed at the bottom of the bottom surface protrusion 23. Therefore, when mounted on the mounting substrate 3, for example, Figure 8 As shown, the shape of the micro-vibrator 2 allows the bonding member 52 to flow from the rear surface 2b side toward the front surface 2a of the bottom surface protrusion 23 through the through hole 24. Therefore, even if the rear surface 2b does not have the conductive layer 25, the micro-vibrator 2 can be electrically connected to the mounting substrate 3 through the bonding member 52 that has flowed into the through hole 24.

[0055] The micro-vibrator 2 is made of, for example, glass, which contains additives such as quartz, and borosilicate glass, metallic glass and / or materials such as silicon and ceramics. The micro-vibrator 2 can be a component configured to form a curved portion 21, a recess 22 and a bottom surface protrusion 23 having a three-dimensional curved surface shape, and is configured to vibrate in a wine glass mode. The micro-vibrator 2 is not limited to being formed by the above-mentioned materials. The micro-vibrator 2 is formed, for example, by processing a thin-walled substrate made of the above-mentioned material through a forming step described later. Therefore, the micro-vibrator 2 is formed so that the curved portion 21, the recess 22 and the bottom surface protrusion 23 have a thickness of 10μm to 100μm, which is a thin component of the micron level. The micro-vibrator 2 has, for example, a millimeter-sized shape, so that the micro-vibrator 2 is 2.5mm in the height direction, and the outer diameter of the micro-vibrator 2 on the front surface 2a side of the edge 211 is 5mm. The height direction is along the thickness direction of the mounting substrate 3.

[0056] The microvibrator 2 is formed by, for example, the following steps.

[0057] First, for example, Figure 4A As shown, a quartz plate 20 for forming a three-dimensional curved surface shape, a mold M, and a cooling body C for cooling the mold M are prepared. The mold M, for example, has a recess M1 that forms a space for forming a three-dimensional curved surface shape on the quartz plate 20, and a support portion M2 that is located at the center of the recess M1 and extends in the depth direction of the recess M1 and supports a portion of the quartz plate 20 in the method. The mold M is formed with a through hole M11 formed in the bottom surface of the recess M1 and a protrusion M21 formed on the tip end surface of the support portion M2. The cooling body C has a mounting portion C1 into which the mold M is assembled and a discharge port C11 formed on the bottom of the fitting portion C1 for discharge. The cooling body C is configured to cool the mold M when processing the quartz plate 20. The quartz plate 20 is arranged so as to cover the entire area of ​​the recess M1 of the mold M.

[0058] Then, for example, Figure 4B As shown, a flame F is applied from a torch T toward the quartz plate 20 to melt the quartz plate 20. At this time, the concave portion M1 of the mold M is evacuated through the discharge port C11 of the cooling body C by a vacuum mechanism (not shown). Therefore, the melted portion of the quartz plate 20 is stretched toward the bottom surface of the concave portion M1. In addition, the central peripheral region of the melted portion of the quartz plate 20 is supported by the support portion M2. Thereafter, the heating of the quartz plate 20 is stopped, and the quartz plate 20 is cooled. Therefore, in the quartz plate 20, a curved surface portion 201 having a substantially hemispherical three-dimensional curved surface shape and a concave portion 202 that is concave at a portion near the center of the curved surface portion 201 along the outer shape of the protrusion M21 are formed. In addition, a portion of the quartz plate 20 located on the outer side of the concave portion M1 becomes a terminal portion 203 located at the outer periphery of the curved surface portion 201 and having a flat shape.

[0059] Subsequently, the concave portion M1 of the mold M is returned to a normal pressure state, and the processed quartz plate 20 is removed. Figure 4C As shown, the quartz plate 20 is sealed by, for example, a sealing material E made of a curable resin material. Figure 4D As shown, the sealing material E is polished, for example, and CMP (Chemical Mechanical Polishing) is applied from the surface on the side of the terminal portion 203. Thus, the sealing material E is removed together with the terminal portion 203 and the tip of the concave portion 202.

[0060] Therefore, the quartz plate 20 has a shape having a curved surface portion 21 having a torroidal curved surface, a recessed portion 22 recessed from the tip end of the curved surface portion 21 , a bottom surface protruding portion 23 , and a through hole 24 .

[0061] Then, all the sealing material E is removed by a method such as heating or melting using a chemical solution, and the quartz plate 20 is removed. Figure 4E As shown in FIG. 1 , a jig J having a recess J1 having an inner diameter corresponding to the outer diameter of the bottom surface protrusion 23 of the quartz plate 20 is prepared, and finally the quartz plate 20 taken out from the sealing material E is set on the jig J. Finally, after the above steps, a conductive layer 25 is formed on the front surface 20a of the quartz plate 20 by a film forming process such as sputtering or thin film deposition. As a result, in the quartz plate 20, the front surface 20a on the side having a large outer diameter is covered with the conductive layer 25, and the rear surface 20b on the opposite surface is exposed.

[0062] The micro-vibration body 2 is manufactured by, for example, the manufacturing steps described above, but is not limited to this example of the manufacturing method. Figure 4B The heat source shown for melting the quartz plate 20 may not be the flame F generated by the torch T, but a heater configured to heat the quartz plate 20 in the same area as when the flame F is used. Figure 4F As shown, the terminal portion 203 can be retained in the state in which Figure 4B After the steps shown in FIG. 1 , the micro-vibration body 2 is manufactured by forming the conductive layer 25 on the outer surface of the quartz plate 20. Figure 4G As shown, the micro-vibration body 2 is formed by the following method: a quartz plate 20 on which a conductive layer 25 is formed is sealed using a sealing material E, and then the end portion 203 is removed by polishing and CMP, and finally the sealing material E is removed. In this case, the quartz plate 20 can be fixed using the end portion 203 to be removed later without using the clamp J. In addition, the quartz plate 20 can be rotated during the vacuum film formation of the conductive layer 25, thereby further suppressing the film formation variation of the conductive layer 25. In addition, the through hole 24 of the micro-vibration body 2 can be formed by a method other than polishing. For example, the micro-vibration body 2 can be formed so that Figure 4AIn the steps shown, a quartz plate 20 having a flat plate shape and having a through hole 24 preformed in a portion on a tip end of a protrusion M21 of a mold M can be prepared, and Figure 4B As described above, the manufacturing steps of the micro-vibrator 2 can be appropriately changed, and other known methods can be adopted.

[0063] Furthermore, in this example, microvibrator 2 has a substantially semi-circular shape which is rotationally symmetrical about the Z direction as a rotation axis. Microvibrator 2 may have a shape configured to vibrate in a wine glass mode, and is not limited to the shape of BR shown in the figure.

[0064] like Figure 5 As shown, for example, the mounting substrate 3 includes a lower substrate 4 and an upper substrate 5 joined to each other. For example, the mounting substrate 3 is formed by anodic bonding of the upper substrate 5 formed of a semiconductor material Si (silicon) and the lower substrate 4 composed of borosilicate glass as an insulating material. The lower substrate 4 of the mounting substrate 3 includes a positioning recess 43 for mounting the micro-vibration body 2 thereon, an inner frame portion 51 surrounding the positioning recess 43, a plurality of electrode portions 53 spaced apart from each other to surround the inner frame portion 51, and an outer frame portion 54 spaced apart from each other to surround the electrode portion 53.

[0065] When viewed from the upper side, the inner frame portion 51 has, for example, a ring shape, but is not limited to this shape. The inner frame portion 51 may have a frame shape surrounding the positioning recess 43. Figure 8 and 9 As shown, for example, inner frame portion 51 has an outer diameter and an inner diameter thereof having such a size that it does not contact micro-vibrator 2 .

[0066] The plurality of electrode portions 53 are disposed spaced apart from each other so as to surround the inner frame portion 51 at positions on the radially outer side of the etching groove 41. Figure 5 As shown, for example, when viewed from the upper side, the plurality of electrode portions 53 have arc-shaped sides on the inner peripheral side and the outer peripheral side. When the inner peripheral side and the outer peripheral side of the electrode portion 53 are connected to each other, intermittent circles of different diameters are drawn. In other words, the plurality of electrode portions 53 have such a configuration that the ring surrounding the inner frame portion 51 is evenly divided at predetermined intervals.

[0067] like Figure 6 As shown, for example, each of the plurality of electrode portions 53 has an electrode film 531 formed on its upper surface. For example, a wire (not shown) is connected to the electrode film 531, and the plurality of electrode portions 53 are electrically connected to an external circuit board (not shown) to achieve control of the potential. Figure 1 and 8As shown, for example, when the micro-vibration body 2 is mounted, the plurality of electrode portions 53 are in a state of being separated from the edge 211 of the micro-vibration body 2 by a predetermined distance, and each of the plurality of electrode portions 53 forms a capacitor with the micro-vibration body 2. That is, the mounting substrate 3 is configured to detect the capacitance with the micro-vibration body 2 through the plurality of electrode portions 53, and to generate an electrostatic attraction force with the micro-vibration body 2, so that the micro-vibration body 2 vibrates in the wine glass mode.

[0068] exist Figure 5 In the top view shown, the "inner peripheral side" of the mounting substrate 3 refers to the inner area surrounded by the inner frame portion 51 on the central side, and the "outer peripheral side" of the mounting substrate 3 refers to the side opposite to the inner peripheral side. Figure 1 , etc. show an example in which electrode portions 53 of 16 elements are uniformly arranged on mounting substrate 3 and separated from each other to form a ring, but the present invention is not limited to this example. The number and arrangement of electrode portions 53 can be appropriately modified according to the shape and size of micro-vibrator 2.

[0069] The outer frame portion 54 has a single frame shape surrounding the inner frame portion 51 in a plan view, and is provided with an electrode film 541 formed of, for example, Al or the like on the upper surface. Figure 5 and 7 A wire (not shown) is connected to the electrode film 541, and the outer frame portion 54 is electrically connected to an external circuit board or the like (not shown). Therefore, the potential of the outer frame portion 54 can be controlled by an external power source (not shown) or the like.

[0070] In the mounting substrate 3, when viewed from the upper side, an annular etching groove 41 is formed around the inner frame portion 51 at a position on the outer peripheral side of the annular inner frame portion 51 in the lower substrate 4. Therefore, when the micro-vibrator 2 is mounted on the mounting substrate 3, the curved surface portion 21 including the edge 211 of the micro-vibrator 2 becomes hollow, for example, Figure 8 and 9 Furthermore, in the mounting substrate 3 , a positioning recess 43 for engaging with the micro-vibrator 2 is formed in an inner region of the lower substrate 4 surrounded by the inner frame portion 51 .

[0071] The mounting substrate 3 has a bridge wire 42 that bridges the etching groove 41 of the lower substrate 4 and covers a part or all of the inner wall and bottom surface of the positioning recess 43. The bridge wire 42 is made of a conductive material such as Al (aluminum) and is arranged to pass between the plurality of electrode portions 53. The bridge wire 42 is electrically independent from the plurality of electrode portions 53. For example, the bridge wire 42 partially extends from the positioning recess 43 as the center portion toward the outer frame portion 54. The extended end of the bridge wire 42 is covered by the outer frame portion 54. Fig. 9As shown, for example, a portion of the bridge wire 42 covering the positioning recess 43 is electrically connected to the conductive layer 25 of the micro-vibration body 2 through the bonding member 52. That is, the bridge wire 42 is used to electrically connect the outer frame portion 54 with the conductive layer 25 of the micro-vibration body 2, so that the outer frame portion 54 and the conductive layer 25 have the same potential. Therefore, the potential of the micro-vibration body 2 is controlled by adjusting the potential of the outer frame portion 54.

[0072] like Fig. 9 As shown, the inner frame portion 51 covers the bridge wire 42, and is at the same potential as the conductive layer 25 through the bridge wire 42 and the bonding member 52. However, it is sufficient that at least the conductive layer 25 and the outer frame portion 54 are at the same potential, and the present invention is not limited to this example. For example, the inner frame portion 51 may have an intermittent frame shape that is partially divided in a top view, and is arranged so as not to abut on the bridge wire 42, and may be at a different potential from the bridge wire 42 and the conductive layer 25.

[0073] like Figure 8 and 9 As shown, for example, the positioning recess 43 is a bottom groove into which the bottom surface protrusion 23 of the micro-vibration body 2 is inserted. For example, the inner diameter of the positioning recess 43 is set to be slightly larger than the outer dimension of the bottom surface protrusion 23 of the micro-vibration body 2. For example, the inner wall and the bottom surface of the positioning recess 43 are partially or completely covered with the bridge line 42. The bottom surface protrusion 23 of the micro-vibration body 2 is inserted into the positioning recess 43, so that the micro-vibration body 2 can be easily and highly accurately positioned relative to the mounting substrate 3. In addition, when the bottom surface protrusion 23 of the micro-vibration body 2 is inserted into the positioning recess 43 of the mounting substrate 3, the area around the positioning recess 43 abuts against the bottom surface 22b, thereby limiting the tilting of the micro-vibration body 2.

[0074] like Fig. 10A As shown, for example, the positioning recess 43 has a dimension in the z direction, i.e., a depth greater than Figure 3 The height of the bottom protrusion 23 shown. That is, the positioning recess 43 has a size such that when the micro-vibration body 2 is engaged, the positioning recess 43 is at a distance from the tip end surface 23b of the bottom protrusion 23. Therefore, the tip end surface 23b of the bottom protrusion 23 of the micro-vibration body 2 and the positioning recess 43 do not contact each other. In addition, the bottom surface 22b contacts the area around the positioning recess 43 in the mounting substrate 3, and limits the inclination of the micro-vibration body 2 relative to the mounting substrate 3. Therefore, the micro-vibration body 2 is in a mounting state in which the distance change between the edge 211 and the plurality of electrode portions 53 of the mounting substrate 3 is reduced, that is, the change in capacitance is reduced. It is sufficient for the bottom protrusion 23 to contact the bottom surface 43a or the bridge line 42 covering the bottom surface 43a for the positioning recess 43. The depth of the positioning recess 43 is appropriately changed according to the height h1 of the bottom protrusion 23.

[0075] The bonding member 52 is not limited to the configuration in which the bonding member 52 fills a portion of the positioning recess 43. From the perspective of further improving the bonding strength between the micro-vibration body 2 and the mounting substrate 3, for example, Fig. 10B As shown, the entire positioning recess 43 may be filled with the bonding member 52. The amount of the bonding member 52 is sufficient as long as the bonding member 52 flows from the positioning recess 43 into the through hole 24 of the micro-vibrator 2 and contacts the conductive layer 25. The amount of the bonding member 52 may be appropriately changed.

[0076] The mounting substrate 3 can be manufactured through, for example, the following steps.

[0077] First, for example, a lower substrate 4 made of borosilicate glass is prepared. An annular etching groove 41 and a positioning recess 43 in a region surrounded by the etching groove 41 are formed by wet etching using buffered hydrofluoric acid. Thereafter, a bridge line 42 is formed across the etching groove 41 and covers the inner wall and bottom surface of the positioning recess 43 by a lift-off method such as using Al sputtering to form a thin film. The thickness of the bridge line 42 is, for example, about 0.1 μm.

[0078] Subsequently, for example, a Si substrate (later, upper substrate 5) made of Si is prepared and anodically bonded to the lower substrate 4 of borosilicate glass. Next, grooves for dividing a region to be the inner frame portion 51, a region to be the plurality of electrode portions 53, and a region to be the outer frame portion 54 are formed on the Si substrate by a known etching method.

[0079] Specifically, for example, trench etching is performed by DRIE (deep reactive ion etching) to expose the lower substrate 4 and to separate the region to be the inner frame portion 51, the region to be the plurality of electrode portions 53, and the region to be the outer frame portion 54 from each other. Thus, the Si substrate becomes the upper substrate 5 including the inner frame portion 51, the plurality of electrode portions 53, and the outer frame portion 54 separated from each other. In addition, the etching groove 41 and the positioning recess 43 formed in the lower substrate 4 are exposed from the upper substrate 5 through the division process of the Si substrate.

[0080] Finally, for example, electrode films 531 and 541 are formed on the upper surfaces of the plurality of electrode portions 53 and the outer frame portion 54 by sputtering or the like. By this method, the mounting substrate 3 having the above-mentioned structure can be obtained. Then, when the micro-vibration body 2 is mounted on the mounting substrate 3, the bonding member 52 is disposed in the positioning recess 43 of the lower substrate 4. The bonding member 52 is, for example, a paste-like conductive material having a conductive material such as AuSn (gold tin), Ag (silver), Au, etc., and is applied to the positioning recess 43 using a syringe or the like.

[0081] For example, the plurality of mounting substrates 3 can be obtained by forming regions each having the above-described structure on a wafer and separating the plurality of mounting substrates 3 into pieces by dicing or the like. Figure 5 The single mounting substrate 3 shown, etc. In other words, the mounting substrate 3 can be manufactured on a wafer level.

[0082] The above is the basic structure of the inertial sensor 1. When driven, the inertial sensor 1 generates electrostatic attraction between a part of the plurality of electrode portions 53 and the micro-vibration body 2, causing the micro-vibration body 2 to vibrate in the wine glass mode. In the inertial sensor 1, when the micro-vibration body 2 is in a vibrating state, when the Coriolis force is applied from the outside, the micro-vibration body 2 is displaced and the position of the vibration mode node changes. The inertial sensor 1 is constructed to detect the angular velocity acting on the inertial sensor 1 by detecting the change of the vibration mode node based on the capacitance between the micro-vibration body 2 and the plurality of electrode portions 53.

[0083]

Manufacturing method of inertial sensor

[0084] Next, refer to Figures 11A to 11E The method of manufacturing the inertial sensor 1 of the present embodiment will be described. Since the manufacturing of the micro-vibrator 2 and the mounting substrate 3 has been described above, the step of bonding the micro-vibrator 2 to the mounting substrate 3 will be mainly described here.

[0085] Figures 11A to 11E Corresponds to Figure 8 In addition, Figures 11C to 11E In the figure, for the sake of ease of viewing, only a portion of the pickup mechanism 300 to be described later is briefly shown, and the interior of the collet 302 is shown by a dotted line.

[0086] First, if Fig.11A As shown, for example, the micro-vibrator 2 and the mounting substrate 3 manufactured by the above method are prepared. Then, for example, Fig. 11B As shown, the bonding member 52 is provided in the positioning recess 43. For example, as the bonding member 52, a conductive bonding material such as gold paste or silver paste is used, and the bonding member 52 is provided by coating with a syringe or the like.

[0087] Then, for example, the mounting substrate 3 is placed on a suction surface (not shown) of the mounting device, and the mounting substrate 3 is fixed by vacuum suction. The mounting device (not shown) has a heating mechanism configured to heat the suction surface.

[0088] Then, for example, Fig. 11CAs shown, a part of the pickup mechanism 300 is inserted into the bottom 22a on the front surface 2a side of the recess 22 of the micro-vibration body 2, and the micro-vibration body 2 is grasped by vacuum suction. The pickup mechanism 300 includes, for example, a base portion 301 and a chuck 302 having a substantially cylindrical shape. The base portion 301 is connected to a conveying portion and a vacuum mechanism (not shown). The pickup mechanism 300 is configured to perform vacuum suction and convey the sucked object through the chuck 302. In the pickup mechanism 300, for example, the maximum diameter of the chuck 302 is smaller than the inner diameter of the recess 22, and the outer diameter of the tip end of the chuck 302 is smaller than the other parts. In addition, in the pickup mechanism 300, the length of the chuck 302 is greater than the depth of the recess 22 of the micro-vibration body 2. When the chuck 302 is inserted into the recess 22 of the micro-vibration body 2, the chuck 302 is configured to be non-contacting with the micro-vibration body 2 except the bottom 22a of the micro-vibration body 2. Therefore, this configuration makes it possible to prevent the conductive layer 25 and the base material of the micro-vibration body 2 from being scratched when the micro-vibration body 2 is transported.

[0089] On the other hand, the mounting substrate 3 is heated in a state of being sucked by a mounting device (not shown) to melt or soften the bonding member 52. Then, for example, Fig.11D As shown, the bottom surface protrusion 23 of the micro-vibrator 2 is inserted into the positioning recess 43 of the mounting substrate 3, and at the same time, the bottom 22a of the micro-vibrator 2 is grasped by vacuum suction using the above-mentioned pickup mechanism 300. Therefore, it is possible to produce such an effect that the positioning of the micro-vibrator 2 relative to the mounting substrate 3 can be performed easily and with high precision. At the same time, it is possible to produce such an effect that the position deviation of the micro-vibrator 2 caused subsequently in the planar direction, that is, on the xy plane, can be limited.

[0090] Subsequently, the micro-vibration body 2 is brought closer to the mounting substrate 3, and the tip end surface 23b of the micro-vibration body 2 contacts the bonding member 52. Therefore, a portion of the melted bonding member 52 enters the through hole 24 of the micro-vibration body 2 and contacts the conductive layer 25 covering the front surface 2a. In addition, since the tip end surface 23b of the bottom surface protrusion 23 does not abut on the positioning recess 43, the inclination of the micro-vibration body 2 relative to the mounting substrate 3 is restricted.

[0091] The micro-vibrator 2 is aligned relative to the mounting substrate 3 so that the micro-vibrator 2 and the mounting substrate 3 are imaged, and feature points are extracted by edge detection by a known image processing technique, thereby adjusting the relative positions.

[0092] Furthermore, as described above, the positioning recess 43 has an inner diameter corresponding to the outer diameter of the bottom surface protrusion 23 of the micro-vibrator 2. Therefore, in addition to adjusting the relative position between the micro-vibrator 2 and the mounting substrate 3 using the image processing technology, by fitting the micro-vibrator 2 to the positioning recess 43, this configuration also makes it possible to easily and highly accurately secure the positioning accuracy of the micro-vibrator 2 relative to the mounting substrate 3.

[0093] Thereafter, the temperature of the suction surface of the mounting device (not shown) is lowered, and the melted bonding member 52 solidifies to bond the micro-vibration body 2 to the mounting substrate 3. Then, for example, Fig.11E As shown, the interior of the chuck 302 returns to normal pressure to release the vacuum suction of the micro-vibration body 2 , retract the pickup mechanism 300 , and pull the chuck 302 out of the recess 22 of the micro-vibration body 2 .

[0094] Subsequently, the suction force generated by the mounting device, etc. (not shown) is released, and the mounting substrate 3 to which the micro-vibrator 2 is joined is removed from the suction surface. Then, the mounting substrate 3 is mounted on a circuit board or the like (not shown), and the electrode films 531 and 541 of the mounting substrate 3 are wire-bonded. In this way, the circuit board, etc., the electrode portion 53 of the mounting substrate 3 and the outer frame portion 54 are electrically connected to each other. Finally, for example, a cover member (not shown) is attached to the mounting substrate 3 or an external member to which the mounting substrate 3 is mounted in a vacuum environment, and the micro-vibrator 2 is tightly sealed in the internal space formed by the mounting substrate 3 and the cover member (not shown). Through such steps, the inertial sensor 1 according to the present embodiment can be manufactured.

[0095] The above is the basic manufacturing method of the inertial sensor 1 of the present embodiment. Here, as a method of grasping the micro-vibrator 2, the case where the bottom 22a of the recess 22 is vacuum-sucked has been described as a typical example, but the method is not limited to this example. For example, the configuration of the chuck 302 may be changed so that the side wall of the recess 22 on the front surface 2a side may be grasped by vacuum-sucking, or the side wall may be grasped by mechanically pressing the side wall at two or more locations.

[0096] According to the present embodiment, the inertial sensor 1 has a structure including a curved portion 21, a recess 22, a bottom surface protrusion 23 and a through hole 24, wherein the micro-vibration body 2 is mounted on the mounting member upper substrate 3, and only the front surface 2a of the micro-vibration body 2 is covered with a conductive layer 25. The inertial sensor 1 has a structure having an electrode film only on the front surface 2a side. Therefore, compared with a structure in which the front surface and the rear surface are entirely covered with an electrode film, the coverage area of ​​the thin-walled substrate of the conductive layer 25 is small, and the effect of improving the Q factor of the micro-vibration body 2 is obtained. In addition, the inertial sensor 1 according to the present embodiment has a structure in which a positioning recess 43 is provided on the mounting substrate 3, and the bottom surface protrusion 23 of the micro-vibration body 2 is inserted, thereby fixing their relative positions. Therefore, compared with simply performing positioning by image processing technology, the inertial sensor 1 has a structure that enables the micro-vibration body 2 to be positioned more easily and with higher accuracy relative to the mounting substrate 3.

[0097] Therefore, inertial sensor 1 according to the present embodiment has a configuration in which the Q factor of micro-vibration body 2 is large and the accuracy is high, while facilitating positioning of micro-vibration body 2 with high accuracy.

[0098] (Other embodiments)

[0099] Although the present invention has been described according to examples, it is to be understood that the present invention is not limited to such examples or structures. The present invention also includes various modifications and modifications within the scope of equivalents. In addition, various combinations and modes, and further combinations and modes including a single element or above or below these are also included in the scope or concept of the present invention.

[0100] (1) For example, in the micro-vibrator 2, Fig.12 As shown, the bottom surface protrusion 23 may have a tapered shape with an inclined surface so that the outer diameter of the tip end portion on the opposite side of the bottom surface 22b is smaller than the outer diameter of the terminal end portion on the bottom surface 22b side. Figure 4A The height of the protrusion M21 of the illustrated mold M is increased, and the tip of the protrusion M21 is formed thinner than the root of the protrusion M21.

[0101] In addition, if Fig.13 As shown, the microvibrator 2 may be shaped, for example, such that the outer surface of the bottom protrusion 23 on the rear surface 2b side is formed into a curved shape that is continuously curved from the bottom surface 22b to the tip end surface 23b, and the outer diameter of the tip end portion becomes smaller. For example, the bottom protrusion 23 may be formed into a curved shape so that Figure 4A The height of the protrusion M21 of the illustrated mold M is reduced, and the tip of the protrusion M21 is formed thinner than the root of the protrusion M21.

[0102] In the configuration in which the outer shape of the bottom surface protrusion 23 has the above-mentioned tapered shape or curved shape, even if the outer diameter of the bottom surface protrusion 23 on the bottom surface 22b side is slightly larger than the inner diameter of the positioning recess 43 due to a dimensional error or the like, the bottom surface protrusion 23 can be easily inserted. Therefore, the micro-vibrator 2 has such a shape that the bottom surface 22b of the recess 22 is stably in contact with the mounting substrate 3, and a more stable positioning effect relative to the mounting substrate 3 can be produced. It should be noted that Fig.12 and 13 1 is an enlarged view showing a region including the bottom surface protrusion 23 of the microvibrator 2 , a part of the bottom surface protrusion 23 , and the recess 22 located near the bottom surface protrusion 23 . Fig.12 and 13 is an enlarged cross-sectional view with other structures omitted for ease of viewing. The same applies to Fig.14 .

[0103] As described above, it is sufficient that the micro-vibrator 2 has the bottom surface protrusion 23 that can be inserted into the positioning recess 43, and the tip end surface 23b does not abut on the positioning recess 43. The shape of the bottom surface protrusion 23 can be changed as needed. For example, the bottom surface protrusion 23 is not limited to a tapered shape, a curved shape, etc. The bottom surface protrusion 23 can have a substantially cylindrical shape extending in the normal direction relative to the bottom surface 22b, that is, extending downward in the z direction.

[0104] (2) The conductive layer 25 may cover part or all of the inner wall of the through hole 24, such as Figure 3 and 12 As shown. Fig.14 The conductive layer 25 shown may not cover the inner wall of the through hole 24. In the former case, at least a portion of the conductive layer 25 is extended so as to connect the upper end of the inner wall of the through hole 24 on the side of the front surface 2a with the lower end of the inner wall of the through hole 24 on the side of the tip end surface 23b, so that when the micro-vibration body 2 is joined, it can stably contact with the joining member 52. Therefore, the effect of more stable electrical connection between the micro-vibration body 2 and the mounting substrate 3 can be produced.

[0105] In addition, it is sufficient that the conductive layer 25 covers at least the front surface 2a of the edge 211 facing the plurality of electrode portions 53 of the mounting substrate 3 and the inner wall surface of the bottom protrusion 23, and electrically connects the two. The conductive layer 25 does not necessarily have to cover the entire front surface 2a. Fig.15 As shown, for example, the conductive layer 25 may have a pattern shape that covers only a portion of the front surface 2a. For example, the conductive layer 25 may have a pattern shape in which a portion covering the edge 211 and a portion covering the inner wall surface of the recess 22 and the bottom protrusion 23 are connected to each other through a narrow portion. In this case, the coverage area of ​​the base material of the micro-vibration body 2 covered by the conductive layer 25 is further reduced, so that the micro-vibration body 2 has a structure that further suppresses the reduction of the Q factor.

[0106] It can be prepared by, for example Figure 4A The micro-vibrator 2 including the conductive layer 25 having the above-mentioned pattern shape is formed by using the flat quartz plate 20 shown in FIG. 1 , wherein the conductive layer 25 having the pattern shape is formed on one side of the recess M1, and by performing Figures 4B to 4E Steps to form. Fig.15 In order to facilitate understanding of the example of the pattern shape of the conductive layer 25 constituting the microvibrator 2, a portion of the curved surface portion 21 of the microvibrator 2 is omitted, and similarly Figure 2 ,exist Fig.15 Portions of the housing that are not visible from the angle shown are shown by dotted lines.

Claims

1. An inertial sensor, comprising: A microvibrator, which is a thin-walled member having a front surface and a rear surface, the front surface being a surface on a side having a large outer diameter, the rear surface being a surface opposite to the front surface, the microvibrator including a curved portion having an annular curved surface, a recessed portion recessed from a top side of the curved portion toward a center side of the curved portion to a rear surface side, a bottom surface protruding portion protruding from a bottom surface of the recess on the rear surface side, a through hole located in the bottom surface protruding portion and connecting the front surface with the rear surface, and a conductive layer covering at least a portion of the front surface; A mounting substrate, comprising a lower substrate and an upper substrate joined to each other, the lower substrate having a positioning recess into which the bottom surface protrusion of the micro-vibrator is inserted, and the upper substrate comprising an inner frame portion having a frame shape and surrounding the positioning recess and a plurality of electrode portions separated from each other and surrounding the inner frame portion; as well as a bonding member which is disposed in the positioning recess and bonds the bottom surface protrusion of the microvibrator to the mounting substrate, wherein The curved surface of the micro-vibrator is hollow. The bottom surface is in contact with a region of the mounting substrate surrounding the positioning recess, The tip end portion of the bottom surface protrusion has a tip end surface below the bottom surface, The positioning recess is spaced a certain distance from the tip end surface, and The bonding member at least partially enters the through hole and is electrically connected to the conductive layer.

2. The inertial sensor according to claim 1, wherein The conductive layer covers at least a portion of the inner wall of the through hole, and The conductive layer extends such that at least a portion of the conductive layer connects an upper end of the inner wall of the through hole on the front surface side and a lower end of the inner wall of the through hole on the rear surface side.

3. The inertial sensor according to claim 1 or 2, wherein The conductive layer covers at least a front surface of an edge of the micro-vibrator, the front surface facing the plurality of electrode portions, and The conductive layer covers only the front surface side.

4. The inertial sensor according to claim 1 or 2, wherein The engaging member fills the positioning recess.

5. The inertial sensor according to claim 1 or 2, wherein The bottom surface protrusion has a tapered shape or a curved shape such that an outer diameter of a tip end of the bottom surface protrusion is smaller than an outer diameter of a bottom end of the bottom surface protrusion.

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