MEMS devices

Abstract

This invention provides a MEMS device that can increase the resonant frequency during the rotation of the movable part, thereby reducing the possibility of arm buckling. [Solution] The MEMS device comprises a movable part rotatable about a rotation axis extending in the width direction, a first support part and a second support part provided on both sides of the movable part in the length direction, a first arm extending from the movable part to the first support part, and a second arm extending from the movable part to the second support part. At least one of the first arm and the second arm comprises a central part, a one-way connecting part extending from the central part toward the movable part and connected to the movable part, and a other-way connecting part extending from the central part away from the movable part and connected to the first support part or the second support part. In the thickness direction, the central part is longer than at least one of the one-way connecting part and the other-way connecting part.

Description

Technical Field

[0001] The present disclosure relates to a MEMS device having a rotatable movable part.

Background Art

[0002] As an example of a microelectromechanical device (Micro Electro Mechanical Systems (MEMS) device) having a rotatable movable part, a MEMS device capable of rotating and tilting a mirror structure is disclosed in Patent Document 1.

[0003] The MEMS device disclosed in Patent Document 1 is composed of a first layer including a stator comb-shaped actuator and a second layer including a rotor comb-shaped actuator. By meshing a plurality of teeth of the stator comb-shaped actuator and a plurality of teeth of the rotor comb-shaped actuator, the mirror structure is driven. Thereby, the mirror structure can be rotated and tilted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the MEMS device disclosed in Patent Document 1, since the stator and the rotor are in different layers, a large electrostatic force is required to greatly tilt the mirror structure. Therefore, there is a possibility that the rotation range of the mirror structure is limited.

[0006] One possible configuration that allows the movable part to rotate significantly without requiring excessively large electrostatic force is one in which the movable part is supported by an arm. However, in the case of a configuration in which the movable part is supported by an arm, the following problems may arise.

[0007] When a movable part is rotated at its resonant frequency, controlling its rotation becomes difficult. Therefore, it is desirable for the rotation of the movable part to be non-resonant. However, arms are usually thin and long. Consequently, in a configuration where the movable part is supported by an arm, the resonant frequency when rotating the movable part may be lower compared to a configuration where the movable part is supported by a thick and short structure.

[0008] Furthermore, because arms are typically thin and long, they are more prone to buckling than thicker and shorter structures.

[0009] Therefore, the object of this disclosure is to provide a MEMS device that can solve the aforementioned problems by increasing the resonant frequency during rotation of the movable part and reducing the possibility of buckling of the arm. [Means for solving the problem]

[0010] A MEMS device in one aspect of this disclosure is A movable part that can rotate around a rotation axis extending in the width direction, In the longitudinal direction intersecting the width direction, the first support portion and the second support portion are provided on both sides of the movable portion, A first arm extending from the movable part to the first support part, It comprises a second arm extending from the movable part to the second support part, At least one of the first arm and the second arm is The central part, One connecting portion extends from the central portion toward the movable portion and is connected to the movable portion, It comprises the central portion extending in the opposite direction from the movable portion and connected to the first support portion or the second support portion, In the thickness direction intersecting the width direction and the length direction, the central portion is longer than at least one of the one connecting portion and the other connecting portion. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide a MEMS device that can increase the resonant frequency during rotation of the movable part and reduce the possibility of buckling of the arm. [Brief explanation of the drawing]

[0012] [Figure 1] A plan view showing a MEMS device according to the first embodiment of this disclosure. [Figure 2] A left side view showing a MEMS device according to the first embodiment of this disclosure. [Figure 3] A left side view showing a modified example of a MEMS device according to the first embodiment of this disclosure. [Figure 4] A left side view showing a modified example of a MEMS device according to the first embodiment of this disclosure. [Figure 5] A left side view showing a modified example of a MEMS device according to the first embodiment of this disclosure. [Figure 6] A left side view showing a MEMS device according to a second embodiment of this disclosure. [Figure 7] A left side view showing a modified example of a MEMS device according to the second embodiment of this disclosure. [Figure 8] A plan view showing a MEMS device according to another embodiment of the present disclosure. [Figure 9] A plan view showing a MEMS device according to another embodiment of the present disclosure. [Figure 10] A plan view showing a MEMS device according to another embodiment of the present disclosure. [Figure 11] A plan view showing a MEMS device according to another embodiment of the present disclosure. [Figure 12] Left side view of a MEMS device equipped with a torsion suspension structure. [Figure 13]Left side view of a modified example of a MEMS device having a torsion suspension structure. [Figure 14] Cross-sectional view for explaining an example of a method for manufacturing a MEMS device. [Figure 15] Enlarged view of the broken line portion of FIG. 1 in the plan view showing the MEMS device according to the modified example.

Best Mode for Carrying Out the Invention

[0013] Hereinafter, an example of the present disclosure will be described with reference to the accompanying drawings. The following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. Also, the drawings are schematic, and the ratios of the respective dimensions etc. do not necessarily match the actual ones. Also, in the following description, terms indicating a specific direction or position (terms including, for example, "up", "down", "right", "left", "front", "rear") may be used as necessary. Also, in this specification and the drawings, the X direction, the Y direction, and the Z direction are defined. The Z direction is the thickness direction of the MEMS device, and the X direction and the Y direction are directions that intersect (orthogonal in the following respective embodiments and drawings) with respect to the thickness direction of the package element. The X direction and the Y direction intersect (orthogonal in the following respective embodiments and drawings) with each other. The X direction is an example of the length direction. The Y direction is an example of the width direction. The Z direction is an example of the thickness direction. The use of the terms indicating the specific direction or position described above is for facilitating the understanding of the present disclosure with reference to the drawings, and the technical scope of the present disclosure is not limited by the meanings of those terms.

[0014] <First Embodiment> FIG. 1 is a plan view showing a MEMS device according to the first embodiment of the present disclosure. FIG. 2 is a left side view showing the MEMS device according to the first embodiment of the present disclosure. In addition, in each of the left side views of FIG. 2 and FIGS. 3 to 7, 12, and 13 described later, illustration of what is behind the first arm 50 and the second arm 60 is omitted.

[0015] The MEMS device 10 shown in Figures 1 and 2 may consist of multiple layers stacked in the Z direction. Each of the multiple layers may be parallel to a plane extending in the X and Y directions. In the first embodiment, the thickness of the MEMS device 10, in other words, the length of the MEMS device 10 in the Z direction, is 50 μm to 100 μm.

[0016] As shown in Figures 1 and 2, the MEMS device 10 comprises a movable part 20, a first support part 30, a second support part 40, a first arm 50, and a second arm 60.

[0017] The movable part 20 is supported by the first support part 30 via the first arm 50 and by the second support part 40 via the second arm 60.

[0018] Furthermore, the movable part 20 is supported on both sides in the Y direction by a frame (not shown). For example, a torsionable shaft (not shown) extends along the Y direction from both ends of the movable part 20 in the Y direction toward the frame. As a result, the movable part 20 is supported by the frame via the shaft and is rotatable about the shaft. The axis of rotation 101 is the axis located at the center of the shaft when viewed along the Y direction and extending along the Y direction. In other words, the movable part 20 is rotatable about the axis of rotation 101.

[0019] In the first embodiment, the movable part 20 is a rectangular parallelepiped and has an upper surface 21, a lower surface 22, a side surface 23, a side surface 24, a side surface 25, and a side surface 26. The upper surface 21 and the lower surface 22 are surfaces that extend in the X and Y directions. The side surfaces 23 and 24 are surfaces that extend in the X and Z directions. The side surfaces 25 and 26 are surfaces that extend in the Y and Z directions. The rotation axis 101 passes through the side surfaces 23 and 24. Note that the shape of the movable part 20 is not limited to a rectangular parallelepiped and may be other shapes such as a cylinder.

[0020] The first support portion 30 and the second support portion 40 are provided on both sides of the movable portion 20 in the X direction. That is, the first support portion 30 is located on one side of the movable portion 20 in the X direction, and the second support portion 40 is located on the other side of the movable portion 20 in the X direction.

[0021] The first support section 30 comprises a support beam 31 and a transducer structure 32 (in other words, a transducer structure 32). The transducer structure 32 comprises a stationary comb-shaped electrode 33 that does not move and a movable comb-shaped electrode 34 that can move. A first arm 50 is connected to the support beam 31. As a result, the support beam 31 supports the movable section 20 via the first arm 50. The movable comb-shaped electrode 34 is fixed to the support beam 31. The stationary comb-shaped electrode 33 is attached to a frame or the like.

[0022] Each of the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 comprises one busbar electrode 35 and a plurality of finger electrodes 36 extending from the busbar electrode 35 along the Y direction. In Figure 1, the stationary comb-shaped electrode 33 has four finger electrodes 36 and the movable comb-shaped electrode 34 has five finger electrodes 36, but the number of finger electrodes 36 is not limited to the above number.

[0023] The busbar electrode 35 of the stationary comb-shaped electrode 33 and the busbar electrode 35 of the movable comb-shaped electrode 34 are positioned opposite each other in the Y direction. The multiple finger electrodes 36 of the stationary comb-shaped electrode 33 and the multiple finger electrodes 36 of the movable comb-shaped electrode 34 are interleaved with each other. In the X direction, adjacent finger electrodes 36 of the stationary comb-shaped electrode 33 and finger electrodes 36 of the movable comb-shaped electrode 34 constitute an electrode pair.

[0024] When a voltage is applied between each pair of electrodes, the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves so that each pair of electrodes moves closer together or further apart. In other words, the movable comb-shaped electrode 34 moves along the X direction, moving closer to and further away from the stationary comb-shaped electrode 33. As a result, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction.

[0025] In the configuration described above, the first support section 30 comprises a support beam 31 and a transducer structure 32, and when a voltage is applied, the support beam 31 to which the first arm 50 is connected moves along the X direction.

[0026] The second support section 40 comprises a support beam 41 and a transducer structure 42 (in other words, a transducer structure 42). The transducer structure 42 comprises a stationary comb-shaped electrode 43 and a movable comb-shaped electrode 44. A second arm 60 is connected to the support beam 41. As a result, the support beam 41 supports the movable section 20 via the second arm 60. The movable comb-shaped electrode is fixed to the support beam 41. The stationary comb-shaped electrode 43 is attached to a frame or the like.

[0027] The second support section 40 has the same configuration as the first support section 30. Therefore, a further detailed explanation of the second support section 40 is omitted. The support beam 41 and the transducer structure 42 correspond to the support beam 31 and the transducer structure 32, respectively. In addition, the stationary comb-shaped electrode 43, the movable comb-shaped electrode 44, the busbar electrode 45, and the finger electrode 46 correspond to the stationary comb-shaped electrode 33, the movable comb-shaped electrode 34, the busbar electrode 35, and the finger electrode 36, respectively.

[0028] In the first embodiment and the embodiments described later, the configurations of the first support portion 30 and the second support portion 40 are not limited to those described above. The first support portion 30 and the second support portion 40 can be any known configuration, provided that the portion to which the first arm 50 and the second arm 60 are connected is movable along the X direction.

[0029] For example, in the configuration shown in Figure 1, the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 are provided between the support beam 31 and the movable part 20, but the support beam 31 may also be provided between the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 and the movable part 20.

[0030] As shown in Figures 1 and 2, the first arm 50 extends from the movable part 20 to the first support part 30. One end of the first arm 50 is connected to the movable part 20. The other end of the first arm 50 is connected to the support beam 31 of the first support part 30.

[0031] The first arm 50 comprises a central portion 501, a one-way connecting portion 502, and a other-way connecting portion 503.

[0032] One-sided connection portion 502 extends from the central portion 501 toward the movable portion 20. One end of the one-sided connection portion 502 is connected to the central portion 501. The other end of the one-sided connection portion 502 is connected to the movable portion 20. The other end of the one-sided connection portion 502 corresponds to one end of the first arm 50. The one-sided connection portion 502 extends along the X direction.

[0033] The other-side connecting portion 503 extends from the central portion 501 toward the support beam 31 of the first support portion 30. One end of the other-side connecting portion 503 is connected to the central portion 501. The other end of the other-side connecting portion 503 is connected to the support beam 31. The other end of the other-side connecting portion 503 corresponds to the other end of the first arm 50. In the first embodiment, the other-side connecting portion 503 extends along the X direction.

[0034] The second arm 60 extends from the movable part 20 to the second support part 40. One end of the second arm 60 is connected to the movable part 20. The other end of the second arm 60 is connected to the support beam 41 of the second support part 40.

[0035] The second arm 60 comprises a central portion 601, a one-way connecting portion 602, and a other-way connecting portion 603.

[0036] One-sided connecting portion 602 extends from the central portion 601 toward the movable portion 20. One end of the one-sided connecting portion 602 is connected to the central portion 601. The other end of the one-sided connecting portion 602 is connected to the movable portion 20. The other end of the one-sided connecting portion 602 corresponds to one end of the second arm 60. In the first embodiment, the one-sided connecting portion 602 extends along the X direction.

[0037] The other connecting portion 603 extends from the central portion 601 toward the support beam 41 of the second support portion 40. One end of the other connecting portion 603 is connected to the central portion 601. The other end of the other connecting portion 603 is connected to the support beam 41. The other end of the other connecting portion 603 corresponds to the other end of the second arm 60. In the first embodiment, the other connecting portion 603 extends along the X direction.

[0038] In the first embodiment, the length of the central portions 501 and 601 in the X direction is 1000 μm, and the length of the one connecting portion 502 and 602 and the other connecting portion 503 and 603 in the X direction is 100 μm. However, the lengths of the central portions 501 and 601, the one connecting portion 502 and 602, and the other connecting portion 503 and 603 in the X direction are not limited to the lengths described above.

[0039] The configurations of the central portion 501, one connecting portion 502, and the other connecting portion 503 of the first arm 50 will be described in more detail below. In the configurations shown in Figures 1 and 2, the central portion 601, one connecting portion 602, and the other connecting portion 603 of the second arm 60 are the same as those of the central portion 501, one connecting portion 502, and the other connecting portion 503 of the first arm 50. Therefore, as a general rule, a more detailed explanation of the configurations of the central portion 601, one connecting portion 602, and the other connecting portion 603 of the second arm 60 will be omitted and explained as needed.

[0040] As shown in Figure 2, the length of the central portion 501 in the Z direction is longer than the length of one connecting portion 502 in the Z direction, and also longer than the length of the other connecting portion 503 in the Z direction. In other words, in the Z direction, the central portion 501 is longer than both the one connecting portion 502 and the other connecting portion 503.

[0041] In the first arm 50, the connection position 50A between the central portion 501 and one connection portion 502 in the Z direction is different from the connection position 50B between the central portion 501 and the other connection portion 503 in the Z direction.

[0042] In the configuration shown in Figure 2, the connection position 50B is located at one end (in other words, the upper end) of the movable part 20 in the Z direction, and the connection position 50A is located at the other end (in other words, the lower end) of the movable part 20 in the Z direction.

[0043] Note that the connection position 50B may be located at a location other than the upper end of the movable part 20, and the connection position 50A may be located at a location other than the lower end of the movable part 20.

[0044] The connection position 20A between the movable part 20 and one connecting part 502 of the first arm 50 in the Z direction is at a different position from the rotation axis 101 in the Z direction. The connection position 20B between the movable part 20 and one connecting part 602 of the second arm 60 in the Z direction is at a different position from the rotation axis 101 in the Z direction. Furthermore, both connection positions 20A and 20B are located on the same side with respect to the rotation axis 101 in the Z direction.

[0045] In the configuration shown in Figure 2, the rotating shaft 101 is located at the upper end of the movable part 20, and the connection positions 20A and 20B are located at the lower end of the movable part 20. In other words, in the configuration shown in Figure 2, the connection positions 20A and 20B are at the same position in the Z direction.

[0046] The rotating shaft 101 may be located at a location other than the upper end of the movable part 20 (for example, at the center of the movable part 20 in the Z direction, as in the second embodiment described later). Also, the connection positions 20A and 20B may be located at a location other than the lower end of the movable part 20 (for example, at the center of the movable part 20 in the Z direction).

[0047] Furthermore, in the configuration shown in Figure 2, connection positions 20A and 20B are at the same position in the Z direction, but connection positions 20A and 20B may be at different positions in the Z direction.

[0048] In the first arm 50, the connection position 50A between the central portion 501 and one connection portion 502 in the Z direction is located on one side in the Z direction relative to the connection position 50B between the central portion 501 and the other connection portion 503 in the Z direction. Similarly, in the second arm 60, the connection position 60A between the central portion 601 and one connection portion 602 in the Z direction is located on one side in the Z direction relative to the connection position 60B between the central portion 601 and the other connection portion 603 in the Z direction. In other words, connection positions 50A and 60A are located on the same side in the Z direction relative to connection positions 50B and 60B.

[0049] In the configuration shown in Figure 2, connection positions 50A and 60A are located at the other end (in other words, the lower end) of the movable part 20 in the Z direction, and connection positions 50B and 60B are located at one end (in other words, the upper end) of the movable part 20 in the Z direction. In the configuration shown in Figure 2, when viewed along the Y direction, the first arm 50 and the second arm 60 are symmetrical with respect to an imaginary line that extends along the Z direction and passes through the rotation axis 101.

[0050] <Modified form of the first embodiment> Figures 3, 4, and 5 are left side views showing modified examples of a MEMS device according to the first embodiment of this disclosure.

[0051] In the configuration described above, the rotation axis 101 is located at the upper end of the movable part 20 in the Z direction, and the connection positions 20A and 20B are located at the lower end of the movable part 20 in the Z direction. However, the rotation axis 101 and the connection positions 20A and 20B are not limited to the positions shown in Figure 2. For example, the rotation axis 101 may be located in the center of the movable part 20 in the Z direction. Also, for example, as shown in Figure 3, the connection positions 20A and 20B may be located in the center of the movable part 20 in the Z direction.

[0052] In the configuration described above, the connection position 50A in the Z direction of the first arm 50 is different from the connection position 50B in the Z direction, and the connection position 60A in the Z direction of the second arm 60 is different from the connection position 60B in the Z direction. However, as shown in Figure 4, the connection positions 50A and 50B may be at the same position in the Z direction, and the connection positions 60A and 60B may be at the same position in the Z direction. Note that in Figure 4, the connection positions 50A, 50B, 60A, and 60B are located in the central part of the movable part 20 in the Z direction, but they may also be located elsewhere, for example, at the lower end of the movable part 20.

[0053] In the configuration described above, as shown in Figure 2, the movable part 20, the first support part 30, the second support part 40, the central part 501 of the first arm 50, and the central part 601 of the second arm 60 are the same length in the Z direction, but they may be of different lengths. For example, as shown in Figure 5, the central part 501 of the first arm 50 and the central part 601 of the second arm 60 may be shorter than the movable part 20, the first support part 30, and the second support part 40 in the Z direction.

[0054] In the configuration described above, in the Z direction, the central portion 501 is longer than both the one connecting portion 502 and the other connecting portion 503, but it is not limited to this. For example, in the Z direction, one of the two connecting portions 502 and the other connecting portion 503 may be longer than or equal to the central portion 501.

[0055] In the configuration described above, the first arm 50 and the second arm 60 have the same configuration, but they may have different configurations.

[0056] For example, in the configuration described above, the connection positions 50A and 60A of the central portion and one connection portion in the Z direction are different from the connection positions 50B and 60B of the central portion and the other connection portion in the Z direction in both the first arm 50 and the second arm 60. However, the connection positions 50A and 60A of the central portion and one connection portion in the Z direction are different from the connection positions 50B and 60B of the central portion and the other connection portion in the Z direction in only one of the first arm 50 and the second arm 60.

[0057] Furthermore, for example, in the configuration described above, both the first arm 50 and the second arm 60 are provided with a central portion, a one-way connecting portion, and a other-way connecting portion. However, only one of the first arm 50 or the second arm 60 may be provided with a central portion, a one-way connecting portion, and a other-way connecting portion. For example, the first arm 50 may be provided with a central portion 501, a one-way connecting portion 502, and a other-way connecting portion 503, while the second arm 60 may not be provided with a central portion 601. In this case, the one-way connecting portion 602 and the other-way connecting portion 603 of the second arm 60 are connected to each other. In this case, the one-way connecting portion 602 and the other-way connecting portion 603 may be configured integrally or separately.

[0058] In the configuration described above, connection positions 20A and 20B are both located on the same side with respect to the rotation axis 101 in the Z direction, but this is not limited to this configuration. For example, as in the second embodiment described later, connection positions 20A and 20B may be located on different sides with respect to the rotation axis 101.

[0059] In the configuration described above, the first arm 50 and the second arm are symmetrical with respect to a virtual line extending along the Z direction and passing through the rotation axis 101, when viewed along the Y direction, but are not limited to this. For example, when viewed along the Y direction, the first arm 50 and the second arm may be approximately symmetrical with respect to the virtual line, or they may not be symmetrical at all.

[0060] <Operation of the MEMS device 10 according to the first embodiment> As described above, when a voltage is applied between each pair of electrodes, the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves along the X direction, moving closer to and further away from the stationary comb-shaped electrode 33. As a result, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction.

[0061] Similarly, when a voltage is applied between each pair of electrodes, the stationary comb electrode 43 and the movable comb electrode 44, the movable comb electrode 44 moves along the X direction, moving closer to or away from the stationary comb electrode 43. As a result, the support beam 41 to which the movable comb electrode 44 is fixed also moves along the X direction.

[0062] As shown in Figure 2, when the support beam 31 moves closer to the movable part 20, a force 111 acts on the movable part 20 via the first arm 50. Also, when the support beam 41 moves away from the movable part 20, a force 112 acts on the movable part 20 via the second arm 60. As a result, the movable part 20 rotates around the rotation axis 101 in the direction indicated by arrow 113.

[0063] Furthermore, as the support beam 31 moves away from the movable part 20, a force 114 acts on the movable part 20 via the first arm 50. Also, as the support beam 41 moves closer to the movable part 20, a force 115 acts on the movable part 20 via the second arm 60. As a result, the movable part 20 rotates about the rotation axis 101 in the direction indicated by arrow 116.

[0064] The MEMS device 10 according to the first embodiment can exhibit the following effects.

[0065] According to the first embodiment, in at least one of the first arm 50 and the second arm 60 (hereinafter, at least one of the first arm 50 and the second arm 60 will also be referred to as the arm), the thickness of the central part is greater than the thickness of at least one of the one connecting part and the other connecting part. As a result, the overall thickness of the arm is increased compared to a configuration in which the thickness of the central part is the same as the thickness of the one connecting part and the other connecting part. As a result, the resonant frequency when rotating the movable part 20 can be increased. Furthermore, as a result, the possibility of the arm buckling can be reduced.

[0066] According to the first embodiment, the thickness of the central part of the arm is greater than the thickness of at least one of the one connecting part and the other connecting part. As a result, when the movable part 20 rotates, the arm is less likely to distort in the central part. Consequently, the distortion of the arm is concentrated at the one connecting part, so the range of rotation of the movable part can be increased.

[0067] According to the first embodiment, in the arm, the connection positions of the central part and one connection part in the Z direction are different from the connection positions of the central part and the other connection part in the Z direction. In other words, the two connection positions are offset in the Z direction. This offset in the Z direction of the two connection positions allows for a large amount of distortion of the arm in the Z direction when the movable part rotates. As a result, the rotation range of the movable part 20 can be increased.

[0068] According to the first embodiment, the movable part 20 can be rotated by applying a force in the same direction to the first arm 50 and the second arm 60.

[0069] According to the first embodiment, the positional relationship between the first arm 50 and the second arm 60 can be made symmetrical or substantially symmetrical when viewed along the Y direction. This allows the movable part 20 to rotate stably when force is applied to the first arm 50 and the second arm 60 to rotate the movable part 20.

[0070] According to the first embodiment, the distance in the Z direction from the connection position 20A of the movable part 20 and the first arm 50 to the rotation axis 101 is the same as the distance in the Z direction from the connection position 20B of the movable part 20 and the second arm 60 to the rotation axis 101. Therefore, the force acting on the first arm 50 and the second arm 60 when the movable part 20 is rotated in one direction in the circumferential direction can be made the same or approximately the same as the force acting on the first arm 50 and the second arm 60 when the movable part 20 is rotated in the other direction in the circumferential direction.

[0071] <Second Embodiment> Figure 6 is a left side view showing a MEMS device according to the second embodiment of this disclosure. The differences from the first embodiment will be explained below. In the second embodiment and each of the embodiments described later, commonalities with the MEMS device 10 according to the first embodiment are denoted by the same reference numerals, and their explanations are generally omitted, and will be explained as necessary.

[0072] As shown in Figure 6, in the MEMS device 10A, connection points 20A and 20B are in different positions in the Z direction.

[0073] In the configuration shown in Figure 6, the rotation axis 101 is located in the center of the movable part 20 in the Z direction. The connection position 20B is located at one end (in other words, the upper end) of the movable part 20 in the Z direction, and the connection position 20A is located at the other end (in other words, the lower end) of the movable part 20 in the Z direction. In other words, in the configuration shown in Figure 6, the rotation axis 101 is located between the connection position 20A and the connection position 20B.

[0074] In the first arm 50, the connection position 50A in the Z direction is located on one side of the Z direction relative to the connection position 50B in the Z direction. Similarly, in the second arm 60, the connection position 60B in the Z direction is located on one side of the Z direction relative to the connection position 60A in the Z direction. In other words, in the first arm 50, the connection position 50A is located below the connection position 50B, and in the second arm 60, the connection position 60B is located below the connection position 60A. In the configuration shown in Figure 6, the first arm 50 and the second arm 60 have the same shape when viewed along the Y direction.

[0075] Furthermore, the position of the rotation axis 101 in the Z direction is not limited to the central part of the movable part 20, but may be, for example, a position between the central part and the upper end of the movable part 20.

[0076] Furthermore, the connection position 20A in the Z direction is not limited to the lower end of the movable part 20, and the connection position 20B in the Z direction is not limited to the upper end of the movable part 20. For example, the connection position 20A in the Z direction may be located between the lower end and the central part of the movable part 20, and the connection position 20B in the Z direction may be located between the upper end and the central part of the movable part 20.

[0077] <Modified form of the second embodiment> Figure 7 is a left side view showing a modified example of a MEMS device according to the second embodiment of this disclosure. In the second embodiment, similar modifications as in the first embodiment can be constructed. Hereinafter, modifications not mentioned in the modifications of the first embodiment will be described, and the description of modifications similar to those of the first embodiment will be omitted.

[0078] In the configuration described above, the connection position 50A in the Z direction of the first arm 50 is different from the connection position 50B in the Z direction, and the connection position 60A in the Z direction of the second arm 60 is different from the connection position 60B in the Z direction. However, as shown in Figure 7, the connection positions 50A and 50B may be at the same position in the Z direction, and the connection positions 60A and 60B may be at the same position in the Z direction. Note that in Figure 7, the connection positions 50A and 50B are located at the lower end of the movable part 20, and the connection positions 60A and 60B are located at the upper end of the movable part 20, but the positions of the connection positions 50A, 50B, 60A, and 60B are not limited to these positions.

[0079] <Operation of MEMS device 10A according to the second embodiment> As described above, when a voltage is applied between each pair of electrodes, the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves along the X direction, moving closer to and away from the stationary comb-shaped electrode 33. As a result, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction. In other words, the transducer structure 32 moves along the X direction.

[0080] Similarly, when a voltage is applied between each pair of electrodes, the stationary comb-shaped electrode 43 and the movable comb-shaped electrode 44, the movable comb-shaped electrode 44 moves along the X-direction, moving closer to or away from the stationary comb-shaped electrode 43. As a result, the support beam 41 to which the movable comb-shaped electrode 44 is fixed also moves along the X-direction. In other words, the transducer structure 42 moves along the X-direction.

[0081] As shown in Figure 6, as the support beams 31 and 41 move away from the movable part 20, force 117 acts on the movable part 20 via the first arm 50 and force 118 acts on the movable part 20 via the second arm 60. As a result, the movable part 20 rotates about the rotation axis 101 in the direction indicated by arrow 119.

[0082] Furthermore, as the support beams 31 and 41 move closer to the movable part 20, force 120 acts on the movable part 20 via the first arm 50, and force 121 acts on the movable part 20 via the second arm 60. As a result, the movable part 20 rotates around the rotation axis 101 in the direction indicated by arrow 122.

[0083] The MEMS device 10A according to the second embodiment can exhibit the following effects.

[0084] According to the second embodiment, the movable part 20 can be rotated by applying forces in opposite directions to the first arm 50 and the second arm 60.

[0085] According to the second embodiment, the positional relationship between the first arm 50 and the second arm 60 can be made point-symmetric or substantially point-symmetric when viewed along the Y direction. Therefore, when force is applied to the first arm 50 and the second arm 60 to rotate the movable part 20, the movable part 20 can be rotated stably.

[0086] According to the second embodiment, the force required to rotate the movable part 20 by a predetermined amount can be reduced compared to a configuration in which the rotation axis 101 is not located between connection positions 20A and 20B in the Z direction.

[0087] <Other Embodiments> In the embodiments described above, each of the MEMS devices 10 and 10A comprises one first arm 50 and one second arm 60. Furthermore, in each of the MEMS devices 10 and 10A, the first support portion 30 comprises one transducer structure 32, and the second support portion 40 comprises one transducer structure 42. However, each of the MEMS devices 10 and 10A may have multiple first arms 50 or multiple second arms 60. Also, in each of the MEMS devices 10 and 10A, the first support portion 30 may have multiple transducer structures 32, and the second support portion 40 may have multiple transducer structures 42.

[0088] Figure 8 is a plan view showing a MEMS device according to another embodiment of the present disclosure.

[0089] As shown in Figure 8, in the MEMS device 10B according to another embodiment, the movable part 20 comprises a main body 27 and two joints 281 and 282. The two joints 281 and 282 are attached to both ends of the main body 27 in the Y direction. Joint 281 is attached to the side surface 23 of the main body 27. Joint 282 is attached to the side surface 24 of the main body 27.

[0090] The MEMS device 10B comprises two first arms 51 and 52 and two second arms 61 and 62. The two first arms 51 and 52 are located at both ends of the MEMS device 10B in the Y direction. The first arm 51 is connected to a joint 281, and the first arm 52 is connected to a joint 282. The two second arms 61 and 62 are located at both ends of the MEMS device 10B in the Y direction. The second arm 61 is connected to a joint 281, and the second arm 62 is connected to a joint 282.

[0091] In the MEMS device 10B, the first support section 30 comprises four transducer structures 321, 322, 323, and 324, and the second support section 40 comprises four transducer structures 421, 422, 423, and 424. The four transducer structures 321, 322, 323, and 324 are located between two first arms 51 and 52 in the Y direction. The four transducer structures 421, 422, 423, and 424 are located between two second arms 61 and 62 in the Y direction.

[0092] In the configuration shown in Figure 8, transducer structures 321 and 324 have the same configuration, and transducer structures 322 and 323 have the same configuration. On the other hand, transducer structures 321 and 324 have different configurations from transducer structures 322 and 323. Specifically, the arrangement order of the finger electrodes 46 in the X direction in transducer structures 321 and 324 is different from the arrangement order of the finger electrodes 46 in the X direction in transducer structures 322 and 323. Transducer structures 421, 422, 423, and 424 also have similar configurations and differences as transducer structures 321, 322, 323, and 324.

[0093] With each transducer structure 321, 322, 323, 324, 421, 422, 423, and 424 configured as described above, the MEMS device shown in Figure 8 operates as follows. For example, transducer structures 321, 324, 421, and 424 may be configured to move in one direction of the X-axis. Alternatively, transducer structures 322, 323, 422, and 423 may be configured to move in the other direction of the X-axis. In this way, the combination of operating transducer structures can initiate movement of the first arm 50 and the second arm 60 in a defined direction (in other words, one or the other direction of the X-axis).

[0094] Figure 9 is a plan view showing a MEMS device according to another embodiment of the present disclosure. In the embodiment shown in Figure 9, commonalities with the MEMS device 10B according to the embodiment shown in Figure 8 are denoted by the same reference numerals, and their descriptions are generally omitted, although they may be described as necessary.

[0095] As shown in Figure 9, the MEMS device 10C according to another embodiment comprises four first arms 51, 52, 53, and 54, and four second arms 61, 62, 63, and 64. The first arms 51 and 53 are connected to a joint 281, and the first arms 52 and 54 are connected to a joint 282. The second arms 61 and 63 are connected to a joint 281, and the second arms 62 and 64 are connected to a joint 282.

[0096] In the MEMS device 10C, transducer structures 321 and 322 are located between first arms 51 and 53 in the Y direction, and transducer structures 323 and 324 are located between first arms 52 and 54 in the Y direction. In the MEMS device 10C, transducer structures 421 and 422 are located between second arms 61 and 63 in the Y direction, and transducer structures 423 and 424 are located between second arms 62 and 64 in the Y direction.

[0097] Figures 10 and 11 are plan views showing a MEMS device according to another embodiment of the present disclosure. In the embodiment shown in Figure 10, commonalities with the MEMS device 10B according to the embodiment shown in Figure 8 are denoted by the same reference numerals, and their descriptions are generally omitted, but will be explained as necessary. In the embodiment shown in Figure 11, commonalities with the MEMS device 10C according to the embodiment shown in Figure 9 are denoted by the same reference numerals, and their descriptions are generally omitted, but will be explained as necessary.

[0098] As shown in Figure 10, the MEMS device 10D according to another embodiment comprises two torsion suspension structures 71 and 72. The torsion suspension structure 71 comprises a torsion spring 711 and a supported portion 712. The torsion spring 711 is fixed at one end to a joint 281 and may extend from the joint 281 along the rotation axis 101. The supported portion 712 is provided at the other end of the torsion spring 711. When the MEMS device 10D is supported by an external housing (not shown), the supported portion 712 is supported by the external housing. The torsion suspension structure 72 has the same configuration as the torsion suspension structure 71 and comprises a torsion spring 721 and a supported portion 722. The torsion spring 721 is fixed to a joint 282 and may extend from the joint 282 along the rotation axis 101.

[0099] One of the functions of the torsion suspension structures 71 and 72 is to support the movable part 20 and reduce its movement in the X or Z direction. Furthermore, the torsion suspension structures 71 and 72 can reduce the driving force required to rotate the movable part 20.

[0100] As shown in Figure 11, the MEMS device 10E according to another embodiment also includes two torsion suspension structures 71 and 72, similar to the MEMS device 10D. However, in the MEMS device 10E, the two torsion suspension structures 71 and 72 are incorporated into the movable part 20. In other words, in the MEMS device 10E, the two torsion suspension structures 71 and 72 are embedded in joints 281 and 282.

[0101] Figure 12 is a left side view of a MEMS device with a torsion suspension structure. Figure 13 is a left side view of a modified example of the MEMS device with a torsion suspension structure. Note that the supported portion 712 is not shown in Figures 12 and 13.

[0102] In the example shown in Figure 12, the torsion springs 711 and 721 are provided at the upper end of the movable part 20. Figure 12 shows an example in which the MEMS device 10 according to the first embodiment is provided with torsion suspension structures 71 and 72.

[0103] The torsion springs 711 and 721 are not limited to the upper end of the movable part 20. For example, the torsion springs 711 and 721 may be provided at the lower end of the movable part 20, at the end of the movable part 20 in the Y direction, or at the center of the movable part 20 in the X direction or the center in the Z direction.

[0104] Furthermore, the torsion springs 711 and 721 may be provided over a wider area than shown in Figure 12. For example, as shown in Figure 13, the torsion springs 711 and 721 may be provided from the upper end to the lower end in the Z direction of the movable part 20. In this case, the length of the torsion springs 711 and 721 in the Z direction is longer than the length of the torsion springs 711 and 721 in the X direction. Figure 13 is an example in which the MEMS device 10A according to the second embodiment is provided with torsion suspension structures 71 and 72. Also, for example, the torsion springs 711 and 721 may be provided from the left end to the right end in the X direction of the movable part 20. The length of the torsion springs 711 and 721 in each direction determines whether the torsion springs 711 and 721 can withstand the forces acting in each direction. For example, if the torsion springs 711 and 712 have sufficient length in the X direction, the torsion springs can be given rigidity against forces acting in the X direction, thereby suppressing movement in the X direction.

[0105] Furthermore, the MEMS device may have three or more torsion suspension structures. For example, the MEMS device may have two torsion suspension structures fixed to joint 281 and two torsion suspension structures fixed to joint 282. In addition, the torsion suspension structures may be attached to locations other than joints 281 and 282, for example, to the sides 23 and 24 of the movable part 20, or to the sides 25 and 26 of the movable part 20. The torsion suspension structures may also be attached to the first arm 50 and the second arm 60.

[0106] A MEMS device may have at least one in-plane suspension structure. For example, as shown in Figure 11, the MEMS device 10E has four in-plane suspension structures 73, 74, 75, and 76. The in-plane suspension structures 73, 74, 75, and 76 are made of, for example, leaf springs. In the configuration shown in Figure 11, the in-plane suspension structures 73 and 74 are attached to both ends of the support beam 31 in the Y direction. The in-plane suspension structures 75 and 76 are attached to both ends of the support beam 41 in the Y direction. Note that the positions where the in-plane suspension structures 73, 74, 75, and 76 are provided are not limited to both ends of the support beams 31 and 41 in the Y direction.

[0107] One function of the in-plane suspension structures 73, 74, 75, and 76 is to fix several components of the MEMS device 10E, reducing movement in the Z or Y direction and allowing movement along the X direction.

[0108] The MEMS device may also be a MEMS mirror. The MEMS devices 10D and 10E shown in Figures 10 and 11 are MEMS mirrors.

[0109] As shown in Figures 10 and 11, the movable part 20 of the MEMS devices 10D and 10E includes a reflector 29. In the MEMS devices 10D and 10E, the main body 27 is frame-shaped. The reflector 29 is supported by the main body 27 so as to be rotatable about a rotation axis 102 extending along the X direction. The structure and operation of MEMS mirrors are well known. Therefore, further detailed explanation of MEMS mirrors is omitted here.

[0110] In the first arm 50 of the MEMS device 10 according to the first embodiment, the lengths in the Y direction of the central portion 501, the one connection portion 502, and the other connection portion 503 are the same. However, the lengths in the Y direction of the central portion 501, the one connection portion 502, and the other connection portion 503 may be different from each other.

[0111] For example, the length of the central portion 501 in the Y direction may be longer than at least one of the lengths of the one connecting portion 502 in the Y direction and the other connecting portion 503 in the Y direction. In the configuration shown in Figure 10, the length of the central portion 501 in the Y direction is longer than the lengths of both the one connecting portion 502 in the Y direction and the other connecting portion 503 in the Y direction.

[0112] Similarly to the first arm 50, the lengths in the Y direction of the central portion 601, the one connecting portion 602, and the other connecting portion 603 of the second arm 60 may be different from each other. In other words, in at least one of the first arm 50 and the second arm 60, the lengths in the Y direction of the central portion, the one connecting portion, and the other connecting portion may be different from each other.

[0113] If the length of the central portion 501 in the Y direction is longer than at least one of the lengths of the one connecting portion 502 and the other connecting portion 503 in the Y direction, vibrations of the first arm 50 and the second arm 60 in the Y direction can be suppressed.

[0114] In addition to the lengths in the Y-direction of the central section, one connection section, and the other connection section mentioned above, the lengths and shapes of each part of the MEMS device are not limited to those shown in the figures above. For example, in the configuration described above, the YZ cross-sections of the first arm 50 and the second arm 60 are rectangular, but these YZ cross-sections may have other shapes, such as circles.

[0115] In the embodiments described above, the side surfaces 36A (see Figure 1) of the finger electrodes 36 provided on the first support portion 30 and the second support portion 40 are planar, but the side surfaces of the finger electrodes 36 are not limited to planar. Here, the side surface 36A of the finger electrodes 36 is the surface facing adjacent finger electrodes 36 in the X direction. Figure 15 is an enlarged view of the dashed line portion in Figure 1 in a plan view showing a modified MEMS device. As shown in Figure 15, each of the side surfaces 36A of the finger electrodes 36 may be comb-shaped. Each comb tooth 36Aa provided on the side surface 36A extends toward adjacent finger electrodes 36 along the X direction. Furthermore, one comb tooth 36Aa of adjacent finger electrodes 36 and the other comb tooth 36Aa of adjacent finger electrodes 36 are positioned alternately in the Y direction.

[0116] <Manufacturing method> Below, a method for manufacturing a MEMS device 10B according to the second embodiment will be described with reference to Figure 14, as an example of a method for manufacturing a MEMS device according to the present disclosure. Figure 14 is a cross-sectional view illustrating an example of a method for manufacturing a MEMS device.

[0117] As shown in (a), a first wafer 801 consisting of three layers 802, 810, and 811 is prepared. In the layer 802 of the first wafer 801, recesses 8031 ​​with a depth d1 in the Z direction are formed in two first regions 803.

[0118] Next, as shown in (b), the first wafer 801 is inverted in the Z direction and attached to the second wafer 804 on which layer 812 is stacked. Layers 810 and 811 may be removed. A recess 8041 with a depth d3 may be formed in the second wafer 804. Due to the formation of the recess 8041, the portion of layer 802 facing the recess 8041 in the Z direction can bend in the Z direction. Layer 802 corresponds to the MEMS device 10B described above.

[0119] Next, as shown in (c), recesses 8051 with a depth d2 in the Z direction are formed in the two second regions 805 of layer 802. In layer 802, the first region 803 corresponds to the other connection portion 503 of the first arm 50 and the one connection portion 602 of the second arm 60. Also in layer 802, the second region 805 corresponds to the one connection portion 502 of the first arm 50 and the other connection portion 603 of the second arm 60. Furthermore, in layer 802, the portion between the first region 803 and the second region 805 corresponds to the central portion 501 of the first arm 50 and the central portion 601 of the second arm 60.

[0120] Next, as shown in (d), layer 802 is penetrated by etching or the like in the third region 806 and the fourth region 807. This makes it possible to form structures corresponding to the first support portion 30 and the second support portion 40 of this disclosure.

[0121] Next, as shown in (e), optionally, the layer 802 can be penetrated in the fifth region 808 to form a structure corresponding to the frame shape of the main body 27 and the reflector 29 in the movable part 20 (see Figures 10 and 11).

[0122] Next, as shown in (f), the cap 809 can be positioned so as to surround the layer 802 between the cap 809 and the second wafer 804. In this arrangement, the structure of the fifth region 808 (in other words, the main body 27 and the reflector 29) can have space to rotate without colliding with the walls of the surrounding structure (e.g., the second wafer 804 and the cap 809).

[0123] The MEMS devices described above can also be expressed as follows.

[0124] (1) The MEMS devices of this disclosure are A movable part that can rotate around a rotation axis extending in the width direction, In the longitudinal direction intersecting the width direction, the first support portion and the second support portion are provided on both sides of the movable portion, A first arm extending from the movable part to the first support part, It comprises a second arm extending from the movable part to the second support part, At least one of the first arm and the second arm is The central part, One connecting portion extends from the central portion toward the movable portion and is connected to the movable portion, It comprises the central portion extending in the opposite direction from the movable portion and connected to the first support portion or the second support portion, In the thickness direction intersecting the width direction and the length direction, the central portion is longer than at least one of the one connecting portion and the other connecting portion.

[0125] (2) In the MEMS device of (1), In at least one of the first arm and the second arm, the connection position between the central portion and the one connection portion in the thickness direction may be different from the connection position between the central portion and the other connection portion in the thickness direction.

[0126] (3) In the MEMS device of (1) or (2), In the thickness direction, the connection position between the movable part and the one connecting part of the first arm, and the connection position between the movable part and the one connecting part of the second arm, may be at a different position from the rotation axis and on the same side with respect to the rotation axis.

[0127] (4) In the MEMS device described in (3), In the first arm, the connection position of the central portion and the one connection portion in the thickness direction may be located on one side in the thickness direction with respect to the connection position of the central portion and the other connection portion in the thickness direction. In the second arm, the connection position between the central portion and the one connection portion in the thickness direction may be located on one side of the thickness direction with respect to the connection position between the central portion and the other connection portion in the thickness direction.

[0128] (5) In the MEMS device of (3) or (4), The connection position between the movable part and the one connecting part of the first arm in the thickness direction may be the same as the connection position between the movable part and the one connecting part of the second arm in the thickness direction.

[0129] (6) In any one of the MEMS devices from (1) to (4), The connection position between the movable part and the one connecting part of the first arm in the thickness direction may be different from the connection position between the movable part and the one connecting part of the second arm in the thickness direction.

[0130] (7) In the MEMS device described in (6), In the first arm, the connection position of the central portion and the one connection portion in the thickness direction may be located on one side in the thickness direction with respect to the connection position of the central portion and the other connection portion in the thickness direction. In the second arm, the connection position between the central portion and the other connection portion in the thickness direction may be located on one side in the thickness direction with respect to the connection position between the central portion and the one connection portion in the thickness direction.

[0131] (8) In the MEMS device of (6) or (7), In the thickness direction, the rotation axis may be located between the connection position between the movable part and the one connecting part of the first arm and the connection position between the movable part and the one connecting part of the second arm.

[0132] (9) In any one of the MEMS devices from (1) to (8), In at least one of the first arm and the second arm, the length of the central portion in the width direction may be longer than at least one of the length of the one connecting portion in the width direction and the length of the other connecting portion in the width direction.

[0133] Furthermore, by appropriately combining any of the various embodiments described above, the effects of each embodiment can be achieved.

[0134] Although the present invention has been fully described in relation to preferred embodiments with reference to the drawings as appropriate, various modifications and alterations will be obvious to those skilled in the art. Such modifications and alterations should be understood to be included within the scope of the invention as defined in the appended claims, as long as they do not fall outside that scope. [Explanation of Symbols]

[0135] 10 MEMS devices 20 Moving parts 20A Connection Location 20B Connection location 30 1st support part 40 Second support part 50 First Arm 50A Connection Location 50B Connection location 501 Central part 502 One-way connection 503 Other connection part 60. Second Arm 60A Connection Location 60B Connection location 601 Central part 602 One-way connection 603 Other connection part 101 Rotation axis

Claims

1. A movable part that can rotate around a rotation axis extending in the width direction, In the longitudinal direction intersecting the width direction, the first support portion and the second support portion are provided on both sides of the movable portion, A first arm extending from the movable part to the first support part, It comprises a second arm extending from the movable part to the second support part, At least one of the first arm and the second arm is The central part, One connecting portion extends from the central portion toward the movable portion and is connected to the movable portion, It comprises the central portion extending in the opposite direction from the movable portion and connected to the first support portion or the second support portion, A MEMS device in which, in the thickness direction intersecting the width direction and the length direction, the central portion is longer than at least one of the one connection portion and the other connection portion.

2. The MEMS device according to claim 1, wherein in at least one of the first arm and the second arm, the connection position of the central portion and the one connection portion in the thickness direction is different from the connection position of the central portion and the other connection portion in the thickness direction.

3. The MEMS device according to claim 1 or 2, wherein, in the thickness direction, the connection position between the movable part and the one connecting part of the first arm and the connection position between the movable part and the one connecting part of the second arm are located at different positions from the rotation axis and on the same side with respect to the rotation axis.

4. In the first arm, the connection position of the central portion and the one connection portion in the thickness direction is located on one side in the thickness direction with respect to the connection position of the central portion and the other connection portion in the thickness direction. The MEMS device according to claim 3, wherein in the second arm, the connection position of the central portion and the one connection portion in the thickness direction is located on one side in the thickness direction with respect to the connection position of the central portion and the other connection portion in the thickness direction.

5. The MEMS device according to claim 3 or 4, wherein the connection position between the movable part and the one connecting part of the first arm in the thickness direction is the same as the connection position between the movable part and the one connecting part of the second arm in the thickness direction.

6. The MEMS device according to any one of claims 1 to 4, wherein the connection position between the movable part and the one connecting part of the first arm in the thickness direction is different from the connection position between the movable part and the one connecting part of the second arm in the thickness direction.

7. In the first arm, the connection position of the central portion and the one connection portion in the thickness direction is located on one side in the thickness direction with respect to the connection position of the central portion and the other connection portion in the thickness direction. The MEMS device according to claim 6, wherein in the second arm, the connection position of the central portion and the other connection portion in the thickness direction is located on one side in the thickness direction with respect to the connection position of the central portion and the one connection portion in the thickness direction.

8. The MEMS device according to claim 6 or 7, wherein in the thickness direction, the rotation axis is located between the connection position between the movable part and the one connection portion of the first arm and the connection position between the movable part and the one connection portion of the second arm.

9. The MEMS device according to any one of claims 1 to 8, wherein in at least one of the first arm and the second arm, the length of the central portion in the width direction is longer than at least one of the length of the one connecting portion in the width direction and the length of the other connecting portion in the width direction.

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