Acceleration sensor and method for manufacturing the same

Abstract

An acceleration sensor with excellent detection sensitivity and a method for manufacturing the acceleration sensor are provided. [Solution] When the directions perpendicular to each other are defined as a first direction, a second direction, and a third direction, the acceleration sensor 1 comprises a fixed part 11 fixed to a substrate 2, a movable body 13 having a movable electrode 20 and movable in the third direction, a torsion spring 14 extending from the fixed part 11 in the first direction and in the direction opposite to the first direction and connecting the movable body 13 and the fixed part 11, a fixed electrode 30 fixed to the substrate 2 and facing the movable electrode 20 in the first direction, and a weight 17 having a specific gravity greater than that of the movable body 13 and attached to the movable body 13, the weight 17 being positioned on the opposite side of the movable electrode 20 from the torsion spring 14 in the second direction.

Description

[Technical Field]

[0001] The present invention relates to an acceleration sensor and a method for manufacturing an acceleration sensor. [Background technology]

[0002] For example, Patent Document 1 discloses an acceleration sensor that has a double-sided seesaw frame attached to a rotor hanger bar extending to the left and right of a rotor anchor point fixed to a substrate, and that includes a torsion spring, a brake plate, a vertical rotor bar, and a horizontal rotor bar having rotor electrode fingers arranged on the rotor rotation shaft, and a horizontal stator bar having stator electrode fingers extending from a stator anchor point fixed to the substrate, and that detects vertical acceleration from a change in capacitance caused by a change in the opposing area between the rotor electrode fingers and the stator electrode fingers due to displacement of the rotor electrode fingers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-23613 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a demand for the acceleration sensor described in Patent Document 1 to have even higher sensitivity. [Means for solving the problem]

[0005] When directions perpendicular to each other are defined as a first direction, a second direction, and a third direction, the acceleration sensor comprises: a fixed portion fixed to a substrate; a movable body having a movable electrode and movable in the third direction; a torsion spring extending from the fixed portion in the first direction and in the direction opposite to the first direction and connecting the movable body and the fixed portion; a fixed electrode fixed to the substrate and facing the movable electrode in the first direction; and a weight having a specific gravity greater than that of the movable body and attached to the movable body, the weight being positioned on the opposite side of the movable electrode from the torsion spring in the second direction.

[0006] The method for manufacturing the acceleration sensor includes the steps of bonding a structural layer to a substrate, forming a weight on the structural layer, and etching the structural layer to form a movable body. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a schematic structure of an acceleration sensor according to a first embodiment. [Figure 2] Cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line CC in FIG. [Figure 5] FIG. 3 is a flowchart showing a method for manufacturing the acceleration sensor according to the first embodiment. [Figure 6] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 7] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 8] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 9] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 10] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 11] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 12] 5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 13]5A to 5C are cross-sectional views illustrating a manufacturing method of the acceleration sensor. [Figure 14] FIG. 10 is a plan view showing a schematic structure of an acceleration sensor according to a second embodiment. [Figure 15] 15 is a cross-sectional view taken along line AA in FIG. 14. [Figure 16] FIG. 10 is a plan view showing a schematic structure of an acceleration sensor according to a third embodiment. [Figure 17] 17 is a cross-sectional view taken along line AA in FIG. 16. [Figure 18] FIG. 10 is a plan view showing a schematic structure of an acceleration sensor according to a fourth embodiment. [Figure 19] 19 is a cross-sectional view taken along line AA in FIG. 18. [Figure 20] FIG. 10 is a plan view showing a schematic structure of an acceleration sensor according to a first modification. [Figure 21] FIG. 10 is a plan view showing a schematic structure of an acceleration sensor according to Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. First embodiment First, the acceleration sensor 1 according to the first embodiment will be described with reference to FIGS. 1, 2, 3, and 4, taking as an example an acceleration sensor that detects acceleration in the vertical direction.

[0009] 1 shows a state in which the cover 4 is removed for the convenience of explaining the internal configuration of the acceleration sensor 1. Furthermore, in FIGS. 1, 2, 3, and 4, the wiring that electrically connects the movable electrode 20 and the fixed electrode 30 provided on the structure layer 3 to the terminal 6 provided on the structure layer 3 is not shown.

[0010] For ease of explanation, the plan views and cross-sectional views below illustrate three mutually orthogonal axes: the X-axis, the Y-axis, and the Z-axis. The direction along the X-axis is referred to as the "X-direction," the direction along the Y-axis as the "Y-direction," and the direction along the Z-axis as the "Z-direction." The tip of the arrow in each axial direction is referred to as the "plus side," the base end as the "minus side," the plus side of the Z direction as the "upward," and the minus side of the Z direction as the "downward." The Z-direction is vertical, and the XY plane is horizontal. In this specification, the first direction is the plus X-direction, the second direction is the plus Y-direction, and the third direction is the combined direction of the plus Z-direction and the minus Z-direction.

[0011] 1, 2, 3, and 4, the acceleration sensor 1 according to this embodiment can detect acceleration in the vertical Z direction. The acceleration sensor 1 includes a substrate 2, a cover 4, and a structural layer 3 having structural members including a fixed portion 11, an electrode fixing portion 12, a movable body 13, and a frame 18.

[0012] As shown in Fig. 1, substrate 2 is a rectangular shape extending in the X and Y directions, has a thickness in the Z direction, is made of a silicon substrate, and has an insulating layer 2a formed by oxidizing the silicon substrate on its upper surface. A plurality of terminals 6 are provided along the X direction on insulating layer 2a on the end side of substrate 2 in the negative Y direction. In addition, as shown in Figs. 2, 3, and 4, substrate 2 has a recess 10 recessed downward from the upper surface of substrate 2 at a position overlapping with movable body 13 of structure layer 3. This recess 10 functions as a relief portion for swinging movable body 13.

[0013] Although a silicon substrate is used as the substrate 2, it is not particularly limited to this, and for example, a glass substrate or a quartz substrate may also be used.

[0014] The lid 4 is made of a silicon substrate and has a rectangular shape extending in the X and Y directions and a thickness in the Z direction. As shown in Figures 2, 3, and 4, the lid 4 has a recess 19 recessed upward from the lower surface, formed at a position where the recess 10 of the substrate 2, the fixed portion 11 of the structure layer 3, the electrode fixed portion 12, and the movable body 13 overlap. The recess 19 functions as a relief portion for allowing the movable body 13 to swing. The lid 4 is bonded onto the frame 18 of the structure layer 3 via a bonding member 5.

[0015] Although a silicon substrate is used as the lid 4, the material is not particularly limited to this, and for example, a glass substrate or a quartz substrate may also be used.

[0016] As shown in FIG. 1 , the structural layer 3 is rectangular in shape, extending in the X and Y directions and having a thickness in the Z direction. It is made of a silicon substrate and is composed of a structure including a fixed portion 11, an electrode fixing portion 12, a movable body 13, and a frame 18. The frame 18 surrounds the fixed portion 11, the electrode fixing portion 12, and the movable body 13. The structural layer 3 is formed by etching a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), or arsenic (As), and particularly by vertical processing using the Bosch process, a deep etching technique. An insulating layer 3a formed by oxidizing the silicon substrate is provided on the upper surfaces of the frame 18 and part of the movable body 13.

[0017] The fixing portion 11, the electrode fixing portion 12, and the frame 18 of the structural layer 3 are fixed onto the substrate 2 by, for example, anodic bonding or activation bonding in which bonding surfaces activated by plasma irradiation are bonded together.

[0018] The fixed portion 11 is connected to the movable body 13 via two torsion springs 14 that extend in the positive X direction, which is a first direction, and in the negative X direction, which is opposite to the first direction.

[0019] Movable body 13 has two torsion springs 14 extending from fixed part 11, two extension parts 15 connected to the respective tip parts of two torsion springs 14 and extending in the +Y direction (a second direction), a connecting part 16 extending in the +X direction (a first direction) and connecting the tip parts of extension parts 15 on the opposite side from torsion springs 14, and a plurality of movable electrodes 20 extending from connecting part 16 in the -Y direction (a second direction) opposite to the +Y direction. Note that movable body 13 is movable in the +Z direction and the -Z direction (a third direction).

[0020] A weight 17 having a larger specific gravity than the movable body 13 is provided on the upper surface of the connecting portion 16 of the movable body 13. The weight 17 is arranged on the opposite side of the torsion spring 14 of the movable electrode 20 in the positive Y direction, which is the second direction. The weight 17 is arranged symmetrically with respect to a center line L, which is a line segment in the positive Y direction, which is the second direction, that passes through the center of the movable body 13 in the positive X direction, which is the first direction. The material of the weight 17 is any one of aluminum (Al), germanium (Ge), and gold (Au).

[0021] There are two electrode fixing parts 12, which are arranged along the X direction in an area surrounded by the fixed part 11 and the movable body 13, and are fixed to the substrate 2. The electrode fixing parts 12 extend in the positive Y direction, which is the second direction, and have a plurality of fixed electrodes 30 that face the movable electrodes 20 in the positive X direction, which is the first direction.

[0022] The movable electrode 20 and the fixed electrode 30 are arranged in a comb-tooth shape, and acceleration in the third direction, the Z direction, can be detected from the change in capacitance caused by the change in the opposing area between the movable electrode 20 and the fixed electrode 30 due to the displacement of the movable electrode 20.

[0023] In this embodiment, the movable electrode 20 includes a first movable electrode 21 and a second movable electrode 22, and the fixed electrode 30 includes a first fixed electrode 31 and a second fixed electrode 32. With respect to a center line L, which is a line segment in the positive Y direction (a second direction) passing through the center of the movable body 13 in the positive X direction (a first direction), the first movable electrode 21 and the first fixed electrode 31 are arranged on the positive X direction (first direction) side, and the second movable electrode 22 and the second fixed electrode 32 are arranged on the negative X direction (opposite the first direction) side. In addition, the first movable electrode 21 has a first recess 23 recessed toward the substrate 2 and is thinner than the opposing first fixed electrode 31, and the second movable electrode 22 has a second recess 33 recessed toward the substrate 2 in the second fixed electrode 32 and is thicker than the opposing second fixed electrode 32.

[0024] Therefore, when acceleration in the positive Z direction is applied, the first movable electrode 21 and the second movable electrode 22 are displaced in the positive Z direction, and the opposing area between the first movable electrode 21 and the first fixed electrode 31 does not change, but the opposing area between the second movable electrode 22 and the second fixed electrode 32 decreases. Conversely, when acceleration in the negative Z direction is applied, the first movable electrode 21 and the second movable electrode 22 are displaced in the negative Z direction, and the opposing area between the first movable electrode 21 and the first fixed electrode 31 decreases, but the opposing area between the second movable electrode 22 and the second fixed electrode 32 does not change. Therefore, by detecting the capacitance value between the first movable electrode 21 and the first fixed electrode 31 and the capacitance value between the second movable electrode 22 and the second fixed electrode 32, it can be determined whether the acceleration is in the positive Z direction or the negative Z direction.

[0025] As described above, in the acceleration sensor 1 of this embodiment, the weight 17 having a larger specific gravity than the movable body 13 is provided at the connecting part 16, which is the tip of the movable body 13 in the positive Y direction, which is the second direction, so that the connecting part 16 is heavy, and when acceleration is applied in the Z direction, which is the third direction, the movable electrode 20 provided at the connecting part 16 can be greatly displaced. Therefore, the opposing area between the movable electrode 20 and the fixed electrode 30 changes greatly, resulting in a large change in capacitance, and the acceleration detection sensitivity can be increased, resulting in a highly sensitive acceleration sensor 1.

[0026] Next, a method for manufacturing the acceleration sensor 1 according to this embodiment will be described with reference to FIGS.

[0027] 6 to 13 are cross-sectional views taken along the line AA in FIG.

[0028] As shown in FIG. 5, the manufacturing method of the acceleration sensor 1 includes a recess forming step S1, a structural layer bonding step S2, a weight forming step S3, a movable body forming step S4, and a lid body bonding step S5.

[0029] First, in the recess formation step S1, the substrate 2 made of a silicon substrate is thermally oxidized to form an insulating layer 2a made of silicon oxide (SiO2) on the upper surface of the substrate 2. Then, as shown in Figure 6, a recess 10 recessed downward from the upper surface of the substrate 2 is formed by vertical processing using the Bosch process, which is a deep etching technique.

[0030] 7, in the structural layer bonding step S2, the structural layer 3 made of a silicon substrate is bonded onto the insulating layer 2a of the substrate 2. As a method for bonding the structural layer 3 and the substrate 2, for example, anodic bonding or activation bonding in which bonding surfaces activated by plasma irradiation are bonded together can be used.

[0031] Next, in a weight formation process S3, the structural layer 3 is thermally oxidized to form an insulating layer 3a made of silicon oxide (SiO2) on the upper surface of the structural layer 3. Thereafter, as shown in Fig. 8, photolithography is used to form a weight 17 on the insulating layer 3a of the structural layer 3 at a position where a connecting portion 16 of the movable body 13 is to be formed, and a terminal 6 at a position where a frame body 18 is to be formed.

[0032] Next, in the movable body forming process S4, a photoresist or the like is applied to form a first hard mask layer 51 on the structural layer 3. Thereafter, as shown in Fig. 9, half etching is performed at a position where the first recess 23 to be provided in the first movable electrode 21 of the movable body 13 is to be formed, thereby forming a depression of the first recess 23 pattern.

[0033] Next, a photoresist or the like is applied onto the first hard mask layer 51 to form a second hard mask layer 52. Using photolithography, the structures of the fixed portion 11, electrode fixing portion 12, movable body 13, and frame body 18 are patterned, and SiO2 dry etching using CHF3 gas is performed to etch the first hard mask layer 51 and the second hard mask layer 52 until the insulating layer 3a is exposed. Thereafter, as shown in Figure 10, the silicon surface of the substrate 2 exposed from the insulating layer 3a is etched to a predetermined depth using the Bosch process, a deep etching technique.

[0034] Next, the second hard mask layer 52 is removed by ashing, and the first hard mask layer 51 is removed by ashing until the insulating layer 3a is exposed in the pattern of the first recess 23. Thereafter, as shown in FIG. 11 , the insulating layer 3a in the pattern of the first recess 23 is subjected to SiO2 dry etching to expose the silicon surface of the structural layer 3.

[0035] Next, a second SiO2 dry etching using CHF3 gas is performed to penetrate the structural layer 3 and form a structure including the fixed portion 11, the electrode fixing portion 12, the movable body 13, and the frame body 18. At the same time, the first recess 23 pattern is also etched to form the first recess 23 having the desired depth. Thereafter, the first hard mask layer 51 is removed by ashing, thereby forming the weight 17 on the connecting portion 16 as shown in FIG. 12, thereby completing the movable body 13 with the first recess 23 of the desired depth. Note that the second recess 33 provided in the second fixed electrode 32 is also formed at the same time.

[0036] Next, in the lid bonding process S5, as shown in Fig. 13, the lid 4 is bonded onto the frame 18 of the structural layer 3 via the bonding member 5. This completes the acceleration sensor 1 in which the weight 17 is formed on the connecting portion 16 of the movable body 13.

[0037] As described above, the manufacturing method for acceleration sensor 1 of this embodiment includes the step of forming weight 17 on connecting portion 16 of movable body 13, so that weight 17 with a larger specific gravity than movable body 13 can be provided at connecting portion 16, which is the tip of movable body 13 in the positive Y direction, which is the second direction. Therefore, when connecting portion 16 becomes heavy and acceleration is applied in the Z direction, which is the third direction, movable electrode 20 provided at connecting portion 16 can be significantly displaced, and the opposing area between movable electrode 20 and fixed electrode 30 changes significantly, resulting in a larger change in capacitance and higher acceleration detection sensitivity. Therefore, a highly sensitive acceleration sensor 1 can be easily manufactured.

[0038] 2. Second embodiment Next, an acceleration sensor 1a according to a second embodiment will be described with reference to FIGS.

[0039] The acceleration sensor 1a of this embodiment is similar to the acceleration sensor 1 of the first embodiment except that the structure of the connecting portion 16a of the movable body 13a is different from that of the acceleration sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and a description of similar points will be omitted.

[0040] As shown in FIGS. 14 and 15, the acceleration sensor 1a includes a substrate 2, a cover 4, and a structural layer 3 having structural members including a fixed portion 11, an electrode fixing portion 12, a movable body 13a, and a frame body 18. The movable body 13a has a groove 40 recessed downward from the upper surface in the connecting portion 16a, and a weight 17a is disposed in the groove 40.

[0041] With this configuration, when acceleration is applied in the third direction, i.e., the Z direction, damage to the movable body 13a caused by the weight 17a colliding with the inner bottom surface of the recess 19 of the lid body 4 can be reduced, and an effect equivalent to that of the acceleration sensor 1 of the first embodiment can be obtained.

[0042] 3. Third embodiment Next, an acceleration sensor 1b according to a third embodiment will be described with reference to FIGS.

[0043] The acceleration sensor 1b of this embodiment is similar to the acceleration sensor 1 of the first embodiment except that the structure of the connecting portion 16b of the movable body 13b is different from that of the acceleration sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and a description of the same points will be omitted.

[0044] As shown in FIGS. 16 and 17, the acceleration sensor 1b includes a substrate 2, a cover 4, and a structural layer 3 having structural members including a fixed portion 11, an electrode fixing portion 12, a movable body 13b, and a frame 18. Movable body 13b has groove 40 recessed downward from the upper surface in connecting portion 16b, and weight 17b is disposed in groove 40. Weight 17b is thicker than groove 40.

[0045] With this configuration, the amount of weight 17b provided in groove 40 can be increased, and the weight of connecting portion 16b can be made heavier, thereby achieving the same effect as that of acceleration sensor 1 of the first embodiment.

[0046] 4. Fourth embodiment Next, an acceleration sensor 1c according to a fourth embodiment will be described with reference to FIGS.

[0047] The acceleration sensor 1c of this embodiment is similar to the acceleration sensor 1 of the first embodiment except for the number of weights 17. The following description will focus on the differences from the first embodiment, and a description of the same points will be omitted.

[0048] As shown in FIGS. 18 and 19, the acceleration sensor 1c includes a substrate 2, a cover 4, and a structural layer 3 having structural members including a fixed portion 11, an electrode fixing portion 12, a movable body 13, and a frame body 18. Movable body 13 has first weight 17c and second weight 17d provided on connecting portion 16, with first weight 17c disposed on the positive X-direction side, which is a first direction, relative to center line L of movable body 13, and second weight 17d disposed on the negative X-direction side, which is opposite to the first direction. First weight 17c and second weight 17d have the same thickness, but the area of ​​first weight 17c is larger than the area of ​​second weight 17d. In other words, first weight 17c is heavier than second weight 17d.

[0049] The mass of the movable body 13 on the first movable electrode 21 side with respect to the center line L is lighter than the mass on the second movable electrode 22 side because the first recess 23 is provided in the first movable electrode 21. Therefore, to compensate for the left and right mass balance of the movable body 13, the first weight 17c provided on the first movable electrode 21 side is made heavier than the second weight 17d.

[0050] In this embodiment, the thickness of the first weight 17c and the second weight 17d is constant and the area is different, but this is not limited to this, and the area of ​​the first weight 17c and the second weight 17d may be the same and the thickness may be different.

[0051] By adopting such a configuration, it is possible to reduce the mass difference between the mass on the first movable electrode 21 side where the first recess 23 is provided in the movable body 13 and the mass on the second movable electrode 22 side, thereby improving the left and right mass balance of the movable body 13, improving detection accuracy, and achieving the same effect as the acceleration sensor 1 of the first embodiment.

[0052] 5. Variations Next, modified examples of the acceleration sensors 1, 1a, 1b, and 1c according to the first to fourth embodiments will be described with reference to FIGS.

[0053] 5.1. Variation 1 20 , in acceleration sensor 1d according to Modification 1, electrode fixing portion 12 and movable body 13 provided with weight 17 are also arranged in the negative Y direction, which is opposite to the second direction of fixed portion 11d, by rotating them by 180°. That is, two torsion springs 14 extend from fixed portion 11 in the positive X direction, which is the first direction, and two torsion springs 14 extend from fixed portion 11 in the negative X direction, which is the opposite to the first direction, and the two torsion springs 14 on the negative Y direction side are each connected to extending portion 15 extending in the negative Y direction, which is the opposite to the second direction. Regarding movable electrode 20 and fixed electrode 30 on the negative Y direction side, second movable electrode 22 and second fixed electrode 32 are arranged on the positive X direction side, and first movable electrode 21 and first fixed electrode 31 are arranged on the negative X direction side. With this configuration, the number of acceleration detection sections becomes four, and the detection sensitivity can be further improved.

[0054] 5.2. Variation 2 21 , in acceleration sensor 1e according to Modification 2, electrode fixing portion 12 and movable body 13 excluding torsion spring 14 are also arranged rotated 180° in the negative Y direction, which is opposite the second direction of fixed portion 11. That is, extending portion 15 is connected to torsion spring 14 extending from fixed portion 11 in the positive X direction, which is the first direction, and extending portion 15 is connected to torsion spring 14 extending from fixed portion 11 in the negative X direction, which is the opposite side to the first direction, and extending portion 15e is connected to each of these extending portions 15. Regarding movable electrode 20 and fixed electrode 30 on the negative Y direction side, second movable electrode 22 and second fixed electrode 32 are arranged on the positive X direction side, and first movable electrode 21 and first fixed electrode 31 are arranged on the negative X direction side. This configuration provides four acceleration detection sections, further enhancing detection sensitivity. The movable body 13 also includes components such as extension sections 15, 15e and connecting section 16 on both sides of the fixed section 11 and torsion spring 14. If the components on both sides of the fixed section 11 and torsion spring 14 were symmetrically arranged, the net rotational moment, i.e., torque, when acceleration is applied may be zero. However, in the acceleration sensor 1e according to Modification 2, as shown in FIG. 21 , the weight 17 is arranged only on the positive Y-direction side of the fixed section 11 and torsion spring 14. This generates a rotational moment, i.e., torque, when acceleration is applied, making the movable body 13 more likely to swing. Thus, in the acceleration sensor 1e according to Modification 2, the weight 17 is arranged asymmetrically with respect to the rotation axis. [Explanation of symbols]

[0055] 1, 1a, 1b, 1c, 1d, 1e...acceleration sensor, 2...substrate, 2a...insulating layer, 3...structural layer, 3a...insulating layer, 4...lid, 5...jointing member, 6...terminal, 10...recess, 11...fixed portion, 12...electrode fixing portion, 13...movable body, 14...torsion spring, 15...extension portion, 16...connecting portion, 17...weight, 18...frame, 19...recess, 20...movable electrode, 21...first movable electrode, 22...second movable electrode, 23...first recess, 30...fixed electrode, 31...first fixed electrode, 32...second fixed electrode, 33...second recess, 40...groove, 51...first hard mask layer, 52...second hard mask layer, L...center line.

Claims

1. When the directions perpendicular to each other are defined as a first direction, a second direction, and a third direction, a fixed portion fixed to the substrate; a movable body having a movable electrode and movable in the third direction; a torsion spring extending from the fixed portion in the first direction and in a direction opposite to the first direction to connect the movable body and the fixed portion; a fixed electrode fixed to the substrate and facing the movable electrode in the first direction; a weight provided on the movable body and having a specific gravity greater than that of the movable body, the weight is disposed on the opposite side of the movable electrode from the torsion spring in the second direction. Acceleration sensor.

2. the movable body has a connecting portion extending in the first direction, the movable electrode extends from the connecting portion in a direction opposite to the second direction, The weight is provided at the connecting portion.

2. The acceleration sensor according to claim 1.

3. The connecting portion is provided with a groove, The weight is disposed within the groove.

3. The acceleration sensor according to claim 2.

4. the weights are disposed symmetrically with respect to a line segment in the second direction that passes through a center of the movable body in the first direction; 3. The acceleration sensor according to claim 1 or 2.

5. the fixed electrode includes a first fixed electrode and a second fixed electrode; the movable electrode includes a first movable electrode thinner than the first fixed electrode and a second movable electrode thicker than the second fixed electrode; With respect to a line segment in the second direction that passes through the center of the movable body in the first direction, the first fixed electrode and the first movable electrode are provided on the first direction side, the second fixed electrode and the second movable electrode are provided on the opposite side to the first direction, the weight includes a first weight provided on the first direction side with respect to a line segment in the second direction passing through a center of the movable body in the first direction, and a second weight provided on the opposite side with respect to the first direction, The first weight is heavier than the second weight.

3. The acceleration sensor according to claim 1 or 2.

6. The material of the weight is any one of aluminum, germanium, and gold.

3. The acceleration sensor according to claim 1 or 2.

7. bonding a structural layer to a substrate; forming a weight on the structural layer; Etching the structural layer to form a movable body. A manufacturing method for an acceleration sensor.

Images